Institute of Solid State Physics Institut für …...1 Technische Universität Berlin Institute of...

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Technische Universität Berlin

Institute of Solid State Physics

Institut für Festkörperphysik

2009 – 2010

Hardenbergstr. 36 D-10623 Berlin

Germany

Phone: (30) 314-220 01 Fax: (30) 314-220 64 E-Mail: [email protected]

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Front Cover

InAs/GaAs submonolayer nanostructures

Design: Dr. Sven Rodt, AG Bimberg

Back Cover

Some of the larger projects and agencies funding our work, 2009 - 2010.

Layout: Dipl.-Phys. Philip Wolf, AG Bimberg

Explanation of the Acronyms on the Back Cover:

100 x 100 Optics: “100 Mbit/sec for 100 Million Users” is a project of the “Fund for Future Development of the State of Berlin” VISIT: “Vertically Integrated Systems for Information Transfer” is an EU FP7 STREP PolarCon: “Polarization Field Control in Nitride Light Emitters" Transregional Research Group funded by the German Research Foundation (DFG) RAINBOW: "High quality material and intrinsic properties of InN and indium rich nitride Alloys" is an EU Marie Curie Initial Training Network (ITN) AGeNT: “Arbeitsgemeinschaft der Nanotechnologie-Kompetenzzentren Deutschlands” The “Association of the Nanotechnology Centers of Competence in Germany” is funded by the Federal Ministry for Education and Research (BMBF) Berlin WideBaSe: “III Nitrides Wide Bandgap Semiconductors” is an innovative regional growth core, funded by the German Federal Ministry for Education and Research (BMBF) SFB 787: “Semiconductor NanoPhotonics” is the Collaborative Research Center 787 of German Research Foundation (DFG) FEMTOBLUE “Blue Femtosecond Laser Implemented with Group-III Nitrides” is an EU 7th FWP (Seventh Framework Programme) project NATO: „ Electrically driven Quantum Dot single Photon Sources for Data Encryption “ is a joint project funded by the NATO Science for Peace and Security Programme HiTrans: „Grundlagen für hochbitratige Transceiver für Optical Interconnect Anwendungen“ is a joint project within the ProFIT-programme funded by the State of Berlin QD2D: „Coupling of Single Quantum Dots to Two-Dimensional Systems is a NanoSci ERA-project funded by the EU-FP 7 - Marie Curie-Work Programme and DFG SANDiE: „ Self-Assembled Semiconductor Nanostructures for new Devices in Photonics and Electronics “ is a Network of Excellence-project of the EU -FP 6 - Nano Material Programme (NMP)

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CONTENTS

1. PREFACE 7

2. PRIZES AND AWARDS 11

3. DISSERTATIONS 13

4. STRUCTURE AND STAFF OF THE INSTITUTE 21

4.1 Office of the Executive Director (01.01.2010) 21 4.2 Departments of the Institute 21 4.3 Workshops 21 4.4 Center of NanoPhotonics 22 4.5 Affiliated Scientific Units 23 4.6 External and Retired Faculty Members of the Institute 27 4.7 Honorary, Adjunct and Guest Professors, Humboldt Awardees and Fellows 27

5. FOREIGN GUESTS 29

6. PARTICIPATION IN COMMITEES 33

6.1 Program and Advisory Committee 33 6.2 Editorial Duties / Boards of Institutes and Companies 35

7. TEACHING 37

8. PATENTS 39

9. SCIENTIFIC ACTIVITIES 41

9.1 Department I Prof. Dr. phil. nat. Dieter Bimberg 41

9.1.1 Staff 41 9.1.2 Summary of Activities 44 9.1.3 Publications 51 9.1.4 Invited Talks 63 9.1.5 Diploma Theses 66

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9.2. Department II 67

9.2.a Department IIa Prof. Dr. rer. nat. Christian Thomsen 67

9.2a.1 Staff 67 9.2a.2 Summary of Activities 69 9.2a.3 Publications 70 9.2a.4 Invited Talks 73 9.2a.5 Diploma Theses 75

9.2.b Department IIb Prof. Dr. rer. nat. Janina Maultzsch 77

9.2b.1 Staff 77 9.2b.2 Summary of Activities 77 9.2b.3 Publications 79 9.2b.4 Invited Talks 80

9.2.c Department IIc Prof. Dr. Axel Hoffmann Prof. em. Dr.-Ing. Dr. h.c. mult. Immanuel Broser 81

9.2c.1 Staff 81 9.2c.2 Summary of Activities 82 9.2c.3 Publications 84 9.2c.4 Invited Talks 89 9.2b.5 Diploma Theses 90

9.3 Department III Prof. Dr. rer. nat. Mario Dähne Prof. em. Dr.-Ing. Hans-Eckhart Gumlich 91

9.3.1 Staff 91 9.3.2 Summary of Activities 92 9.3.3 Publications 96 9.3.4 Invited Talks 98 9.3.5 Diploma Theses 100

9.4 Department IV Prof. Dr. rer. nat. Michael Kneissl Prof. Dr. rer. nat. Wolfgang Richter (retired) 101

9.4.1 Staff 101 9.4.2 Summary of Activities 103 9.4.3 Books 108 9.4.4 Publications 108 9.4.5 Invited Talks 113 9.4.6 Diploma, Master-, and Bachelor Theses 116

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1. PREFACE

The Institute of Solid State Physics presents its eleventh biannual progress report in an

advanced lay-out. Founded in 1974 the Institute is located since 1985 in the Eugene Paul

Wigner Building at Hardenbergstraße, next to the center of Berlin. There it disposes of

spacious lecture halls, seminar rooms and state-of-the-art laboratories. Our scientific work is

focussed on epitaxial growth of compound semiconductor hetero- and nanostructures,

research on novel materials like carbon nanotubes, physics of semiconductor and carbon

nanostructures, as well as physics and technology of nano-photonic and –electronic devices

and systems. Development of nanoscopic measurement techniques, like

cathodoluminescence, cross-section scanning tunneling microscopy, near field scanning

optical microscopy, microphoto-luminescence, and micro-Raman are essential and common

basis of the research activities of our four scientific departments.

In the “Center of NanoPhotonics” CNP, affiliated to the institute, novel devices like Single

and Entangled Photon Emitters, high bit rate and energy efficient Vertical

Surface Emitting Lasers, QD high speed Edge Emitters and Semiconductor Optical

Amplifiers, high power Photonic Band Crystal Lasers, Nanoflash memories, ultraviolet

LEDs, GaN-based external cavity surface emitting lasers, and high power blue and green laser

diodes… are developed, based on a multitude of often complex heterostructures. Most

modern education and research on devices and their technology are offered here to our

students and PhD candidates. In addition, the CNP provides assistance to small and medium

size companies and has acted in the last 2 years as incubator for three start-ups: VI Systems in

Berlin, PBC Lasers in Berlin, and Azzurro Semiconductors in Magdeburg.

The Berlin government agreed to the joint proposal of our faculty and the president for the

creation of both, a new chair on “Quantum Devices” and an additional Junior Professorship

on “Optoelectronic Devices” at the institute. Both positions are expected to be filled in the

first half of 2011.

The success of the institute and the large number of students, PhD candidates and postdocs it

employs, depends now since more than a decade mostly on external financial resources. The

funding from TUB and our state government in Berlin covers less than 20 % of cost of

consumables and equipment. The most important funding agency continues to be the German

Research Foundation (DFG). The Collaborative Research Center (CRC) “Semiconductor

Nanophotonics” (Sfb 787), and its Integrated Research Training Group are located at the

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institute. The CRC is funded since January 1st, 2008 for four years, and showed an excellent

start. Cooperation on nanostructure and photonic device research with colleagues from five

other institutions in Berlin (Humboldt University, Ferdinand-Braun-Institute, Heinrich-Hertz-

Institute, Weierstraß-Institute, Konrad-Zuse-Center) and the University of Magdeburg

presents the basis of the CRC 787. In summer 2011 the CRC hopes for getting a

recommendation by its reviewers towards a prolongation until end of 2015. In addition, single

projects focussing e.g., on collaboration with Russia, on Nanomemories, on GaN-based

Semiconductor Disk Lasers, and the electronic structure of InGaN surfaces were funded by

DFG. We are also participating in the transregional DFG research group 957 (PolarCon) in

which laser and light emitting devices on semipolar GaN surfaces are investigated at TU

Berlin.

Complementary and very important funding came from the government of the State of Berlin

in the framework of its “Zukunftsfonds” and ProFIT Programs. 100 x 100 Optics, HiTrans,…

are some of the projects. The European Union within its FP 7 Program and the NATO

Program “Science for Peace” funded the programs VISIT, QD 2D, PROPHET, FemtoBlue,

RAINBOW, and Cyber Security, respectively. Half of these programs are also coordinated by

TUB.

The national competence center CC NanOp (Nano-Optoelectronics), established already in

October 1998, presented again a very effective and successful means for initiating important

national and European programs on nanodevices. Many of these projects emerged from small

scale projects, so called “Machbarkeitsstudien”, financed by the Federal Ministry of

Education and Research (BMBF) via NanOp. TUB therefore decided to continue its support

of CC NanOp until end of 2011. Based on this decision, the BMBF decided to entrust TUB

with the coordination of all National Centers of Competence in Nanotechnology within a new

body called AGeNT, presently also funded until end of 2011.

The European Union Center of Excellence “SANDiE” in the field of semiconductor

nanostructures, which was cofounded by us, received a continuation of its operation in a

second phase until 2012. Strong links to leading international optoelectronic and

communication companies like Aixtron, INTEL, Jenoptik, Oclaro, OSRAM Opto

Semiconductors, and Sentech have been established within the framework of this program.

We congratulate to the bestowal of an Alexander von Humboldt Award to Professor Shun-

Lien Chuang from University of Illinois at Urbana - Champaign, who joined us beginning of

2009, developing with his host a very successful program on novel “metal clad (some times

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called “plasmonic”) surface emitting lasers”. Professor Gadi Eisenstein, Technion Haifa,

Humboldt Awardee 2006/7 continues to be in Berlin part of each year and supports

enormously our work on high sped devices. We are every grateful to him. Dr. Chongyan Liu

from Nanyang Technological University in Singapore and Dr. Abdul Kadir from the Tata

Institute for Fundamental Research in Mumbai received Alexander von Humboldt

Fellowships in 2009 and are both presently working here.

Prof. Janina Maultzsch received in 2009 a particularly well funded and highly competitive EU

Junior Researcher Starting Grant. We are very proud on her.

A particularly important new development of the last two years was that a number of

postdoctoral scientists and Ph.D. candidates have joined us with full financial support of their

home governments based on the excellent research conducted by the institute.

We are very grateful to all our sponsors, their administrators and cooperating industry for

their continuous help and encouragement.

In order to protect our intellectual property better than in the past and to have a better basis for

cooperation with the industry, we filed and obtained an appreciable number of patents. The

support by our local patent agency IPAL proved here to be of outmost importance.

The scientific part of the present report will certainly provide sufficient evidence that the

funding we received carried excellent results. Particular appreciation of our scientific

achievements was expressed by the bestowal of a number of awards to students and postdocs

listed in part 2 of the report.

Physics is a science not bound to a country or to borders. This ”discovery” led to an

increasing number of our students and scientists in the past to pursue their research for longer

time like a year at foreign universities in Tokyo, Los Angeles, Glasgow, Texas, Berkeley, …

to mention only a few. We would like to thank particularly their local hosts. We will further

encourage our co-workers to combine the challenges of different cultures and languages with

achievements in their scientific work.

Scientific contacts with further institutions at many different locations in Europe, Japan or

USA continued to flourish. Especially strong collaborations including short time exchange of

scientists developed or continued to research institutions and universities in Beijing,

Cambridge, Cork, Göteborg, Novosibirsk, South Carolina, St. Petersburg, Taipei,… to

mention only a few.

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Additional and particularly large burdens were taken over by all of the faculty staff of the

institute in order to serve TUB and the scientific community as members or chairmen of

committees on the local, national and international scale, e.g., within advisory or program

committees.

The reelection of Prof. Christian Thomsen as Dean of the Faculty of Mathematics and Science

in spring 2009 and his devotion for developing multimedia eLearning and eResearch should

be particularly mentioned here.

Finally, the enthusiasm and the dedication of all of our collaborators at the institute should be

honoured, being fundamental to our success. The key element for future progress of the

institute continues to be their motivation to generate new ideas and to work hard.

This report will

- give an overview of the formal structure of the institute and list staff and students

- summarize our teaching activities in order to provide information on our involvement in

the education of young students and scientists

- summarize the scientific activities of our research groups, including lists of the

approximately 200 scientific papers we published or which have been accepted for

publication within the past 24 months.

Dieter Bimberg

Executive Director

March 2011

Postscriptum

After having served as excecutive director of the institute for more than two decades,

initiating a complete restructuring of its research directions, creating state-of-the-art MOCVD

laboratories and the Center of NanoPhotonics amongst many other things I retired from this

position in April 2011. I wish my successor, Michael Kneissl, all the success he will need to

guide the institute through the next years.

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2. PRIZES AND AWARDS

Prof. Dr. Dieter Bimberg William-Streifer Scientific Achievement Award

as “Pioneer of Semiconductor Nanophotonics”

IEEE Society, Denver, Colorado, USA, November 2010

Dipl.-Phys. Gordon Callsen Physik-Studienpreis 2010 der Wilhelm und Else Heraeus-

Stiftung

Magnus-Haus Berlin, Germany, Juli 2010

Dipl.-Phys. Gerrit Fiol Chorafas-Prize 2009 for his investigation of the

“Quantum Dot Lasers for Short Pulse Generation“

Dimitri N. Chorafas Foundation,

Luzern, Switzerland, July 2009

Dipl.-Phys. Tim Germann CHORAFAS-Prize of the year 2010 for his investigation

of “Quantum Dot Semiconductor Disk-Lasers “

Dimitri N. Chorafas Foundation,

Luzern, Switzerland, August 2010

Dr. Lena Ivanova Best Poster Award

International Nano-Optoelectronic Workshop (iNOW)

Stockholm, Sweden, and Berlin, Germany, August 2009

Dr. Lena Ivanova SKM-Dissertationspreis,

Sektion Kondensierte Materie (SKM) der Deutschen

Physikalischen Gesellschaft (DPG)

Regensburg, Germany, March 2010

Dipl.-Phys. Raimund Kremzow Best Poster Award (1st Prize)



M.Sc.-Phys. Neysha Lobo Honorable Mention Best Poster Award



Dr. Andreas Marent Nanowissenschaftspreis 2010 by AGeNT-D

(second place) together with Dr. Martin P. Geller

Prof. Dr. Janina Maultzsch ERC Starting Independent Researcher Grant 2010

European Research Council, ERC, July 2010

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Dr. Alex Mutig SANDiE-PhD-Preis 2010

SANDiE-Network of Excellence,

September 2010, Valencia, Spain

Dr. Alex Mutig Springer PhD-Prize

for his thesis “High Speed VCSELs for Optical

Interconnects” in the book series Springer Thesis,

Heidelberg, January 2011

Dipl.-Phys. Erik Stock 1st place in Section 1: Nanoelectronics, Nanophotonics,

Nanomaterials for Electronics, Magnetic Systems, and

Optics, Photovoltaics for his paper:

”GHz Electrically driven microcavity single photon

source”

Second International Competition of Scientific Papers in

Nanotechnology for Young Researchers at Rusnanotech

2009, Moscow, Russia, October 2009

Dr. Hagen Telg Carl-Ramsauer Prize 2010 for his excellent dissertation,

Berlin, Germany, November 2010

Dr. Tim Wernicke Honorable Mention Best Poster Award, iNOW-



Dr. Tim Wernicke Chorafas Prize for his dissertation on “Growth of non-and

semipolar InAlGaN heterostructures for high efficiency

light emitters”, Berlin, Germany, October 2010

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3. DISSERTATIONS

Department I

Dr. Till Warming Elektronische Struktur angeregter Zustände einzelner InAs-Quantenpunkte Electronic structure of excited states of single InAs quantum dots

20.02.2009

Photo excitation spectroscopy and resonant photoluminescence spectroscopy were combined to unambiguously identify the main excitation and recombination channels of single quantum dots, as well as the corresponding energy levels. By comparison with theoretical results, the impact of exchange interaction and the resulting fine-structure splitting can be deduced – one of the key parameters for single-QD devices.

Thesis reviewers: D. Bimberg, A. Hoffmann (TUB) and J. Christen (Otto-von-Guericke University, Magdeburg)

Dr. Konstantin Pötschke Untersuchungen zur Bildung von Quantenpunkten im Stranski-Krastanow und im Submonolagen Wachstums-modus Formation of quantum dots in Stranski-Krastanow and Submonolayer growth mode

27.02.2009

In this work, Konstantin Pötschke extended the understanding of the formation of InAs quantum dots in the Stranski-Krastanow growth mode. For the first time, the influence of all main growth parameters on the luminescence properties of InAs/GaAs nanostructures, grown in the submonolayer growth mode, was studied comprehensively and systematically, and the electronic and optical properties of these structures were discussed.

Thesis reviewers: D. Bimberg and A. Krost (Otto-von-Guericke University, Magdeburg)

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Dr. Anatol Lochmann Entwicklung und Untersuchung quantenpunktbasierter Einzelphotonenquellen Development and investigation of quantum dot based single photon sources 30.04.2010 This thesis presents the development and implementation of various novel and patented concepts of single photon sources. The first approach for single photon sources based on electrically-driven QDs is the use of a micron-size aluminum-oxide aperture. In this device, only one electron and one hole at a time tunnel into one QD. The next step was the development of a Resonant Cavity LED-type (RCLED) single photon source in order to increase the output coupling efficiency and the QD emission rate. Furthermore, detailed numerical device modeling was performed, in order to do a systematic optimization process of the device design. As the result, the presently fastest electrically pumped, quantum dot based single photon sources could be realized.

Thesis reviewers: D. Bimberg and A. Hoffmann (TUB)

Dr. Thorsten Kettler Halbleiterlaser hoher Brillanz High Brightness Semiconductor Lasers

04.05.2010 In his dissertation Thorsten Kettler studied photonic-band-crystal (PBC) lasers, a new approach to obtain high output powers with extremely low vertical far-field divergence, excellent beam quality and therewith a high brightness of the emitted beam. PBC lasers have a broad waveguide in vertical direction, composed of alternating layers with different refractive index. These layers build a one-dimensional photonic crystal, discriminating higher-order modes so that single-mode emission can be reached in spite of the large near-field dimension. Thorsten processed and characterized single lasers as well as laser arrays built of optically coupled and uncoupled emitters. These lasers showed vertical far-field divergences down to 6°, single-mode lasers demonstrated output powers up to 3.5 W.

Thesis reviewers: D. Bimberg and M. Weyers (Ferdinand-Braun-Institut, Berlin)

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Dr. Alex Mutig Oberflächenemittierende Quantenpunktlaser High-speed VCSELs for optical interconnects

15.07.2010

In his doctorate Alex Mutig focused on the research of high-speed 850 nm and 980 nm vertical-cavity surface-emitting lasers (VCSEL). He was able to achieve highly recognized world-record performance like data rates up to 40 Gbit/s or highly temperature-stable devices. His research included all aspects from device design, manufacturing in a class 10 clean-room, high-speed characterization to thorough data analysis. His thesis was awarded with the Springer Prize and published as a book within the series “Springer Theses: Recognizing Outstanding PhD Research”.

Thesis reviewers: D. Bimberg and S.L. Chuang (University of Illinois, USA)

Dr. Andreas Marent Entwicklung einer neuartigen Quantenpunkt-Speicherzelle Development of a novel quantum dot memory cell

22.10.2010 In this work the charge carrier dynamics in quantum dot based memory structures has been investigated experimentally as well as theoretically and prototypes of a novel memory concept have been implemented. The work is divided in two parts: 1. Development and application of measurement techniques and simulation methods to investigate the memory operations (storage, writing and erasing) in quantum dot based memory structures. 2. Development of quantum dot based memory concepts which fulfill the prerequisites of the ultimate memory (storage time > 10 years and write time < 10 ns) and the implementation of these concepts by prototypes.

Thesis reviewers: D. Bimberg and J. Christen (Otto-von-Guericke University, Magdeburg)

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Dr. Erik Stock Self-organized quantum dots for single photon sources 03.12.2010 In his thesis Erik Stock studied self organized quantum dots for their application as sources for single photons and entangled photon pairs.

Prototypes of electrically pumped single photon devices could be driven with a pumping rate of up to 1 GHz, still demonstrating non-classical light emission. The characterization of quantum dots grown on (111) GaAs substrates showed a strongly reduced fine-structure splitting in comparison to (001) grown QDs, making these new quantum dots a promising candidate for the generation of entangled photons. The first observation of a LO-phonon replica from a single InGaAs QD demonstrates the influence of the wavefunction on the phonon coupling.

Thesis reviewers: D. Bimberg and V. Gaysler (Institute of Semiconductor Phyiscs, Novosibirsk, Russian Federation)

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Department II

Dr. Holger Lange Optical phonons in colloidal CdSe nanorods

05.11.2009

Dr. Hagen Telg Raman studies on individual nanotubes and nanotube ensembles – vibrational properties and scattering efficiencies

06.11.2009

Dr. Stephan Brunken Metallsulfid-unterstützte Kristallisation von stark (001)-texturierten Wolframsulfidschichten

25.11.2009

Dr. Thomas König Investigation of Defects on MgO Films grown on Ag(001)- Combined Dynamic Force and Scanning Tunneling Microscopy Study

01.07.2010

Dr. Marcel Mohr Electronic and Vibrational Properties of Carbon and CdSe nanostructures

23.07.2010

Dr. Dirk Heinrich Strukturbildung in Ferrofluiden unter Einfluss magnetischer Felder

02.09.2010

Dr- Matthias Müller Electronic properties of functionalized carbon nanotubes

08.12.2010

Dr. Munise Cobet Ellipsometric Study of ZnO from multimode formation of exciton-polartons tot he core-level regime

12.07.2010

Dr. Markus R. Wagner Fundamentel properties of excitons and phonons in ZnO: A spectroscopic study oft he dynamics, polarity, and effects of external fields

09.12.2010

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Department III

Dr. Kai Hodeck Development of a scanning nearfield optical microscope for low-temperature investigations of semiconductor nanostructures

19.02.2009 Using a home-built scanning nearfield optical microscope (SNOM), the photoluminescence of single quantum dots was investigated under varying excitation intensity at different temperatures between 5 K and 300 K. The homogeneous thermal line broadening was studied in detail, and the binding energies of exciton complexes such as biexcitons and trions could be determined.

Dr. Lena Ivanova Nitrogen containing III-V semiconductor surfaces and nanostructures studied by scanning tunneling microscopy and spectroscopy

01.09.2009 Using cross-sectional scanning tunnelling microscopy (XSTM) and spectroscopy (XSTS), different nitrogen containing III-V semiconductor surfaces and nanostructures were studied. In diluted GaAsN single nitrogen atoms could be identified, a splitting of the GaAs conduction band could be observed in the density of states, and nitrogen-containing InAs quantum dots were found to be strongly dissolved. In atomically-resolved experiments at the GaN(1100) cleavage surface the intrinsic surface states were found to be outside the fundamental band gap, different dislocation types could be characterized in detail, and doping modulation effects could be detected.

Dr. Jan Grabowski On the evolution of InAs thin films grown by molecular beam epitaxy on the GaAs(001) surface

14.12.2010 Thin InAs films were grown on GaAs(001) by molecular beam epitaxy and studied by in-situ scanning tunnelling microscopy (STM). A three-step evolution of the InAs wetting layer was found, starting with In agglomerations on the GaAs surface, followed by the formation of a (4×3) reconstructed In2/3Ga1/3As monolayer, on which a (2×4) reconstructed InAs monolayer was grown. Afterwards the formation of InAs quantum dots occurred and the critical thickness could be determined to 1.42 InAs monolayers.

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Department IV

Theodor Herrmann Optische Spektroskopie an Metallen und

ferromagnetischen Filmen

02.11.2009 Metal surfaces show superstructures that can be detected via electron diffraction or optical anisotropy. Optical anisotropies can be also caused by applying a magnetic field in certain geometries (MOKE: magneto-optical Kerr effect). To separate the surface anisotropies from the MOKE signals, knowledge of the clean and covered surfaces is required.

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Marc Gluba Atomare und elektronische Struktur von Akzeptorkomplexen und Oberflächen des Zinkoxids

06.07.2010 ZnO semiconductors exhibit a strong background n-type conductivity. Therefore, the p-doping of ZnO poses great difficulties. Different causes for the inability to achieve reproducible p-type doping in ZnO were investigated, particularly the formation of intrinsic point defects, compensation, and the formation of molecular nitrogen.

Tim Wernicke Wachstum von nicht- und semipolaren InAlGaN-Heterostrukturen für hocheffiziente Lichtemitter

15.07.2010 Non- and semipolar nitrides do not exhibit the polarization fields across quantum wells that reduce oscillator strength and peak gain as in conventional polar nitride devices. Different concepts for heteroepitaxial and homoepitaxial growth of non- and semipolar GaN were compared. Bulk GaN substrates exhibit the best properties and were used to demonstrate nonpolar current injection LEDs and violet and blue optically pumped non- and semipolar laser structures with low thresholds.

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Raimund Kremzow In situ Rastertunnelmikroskopie an V-III-Halbleiternano-strukturen während der Metallorganischen Gasphasen-epitaxie

22.10.2010 A scanning tunneling microscope (STM) was attached to a metal-organic vapor phase system, to follow the development of the surface topography with atomic resolution. During the work the setup was extended by a spectroscopic ellipsometer. Using this setup the first ever study of Ostwald ripening of InAs quantum dot in MOVPE was performed.

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4. STRUCTURE AND STAFF OF THE INSTITUTE

4.1 Office of the Executive Director (01.01.2010)

Prof. Dr. phil. nat. Dieter Bimberg (executive director)

Prof. Dr. rer. nat. Christian Thomsen (deputy executive director)

Prof. Dr. rer. nat. Mario Dähne (deputy executive director)

Prof. Dr. rer. nat. Michael Kneissl (deputy executive director)

Prof. Dr. rer. nat. Axel Hoffmann (chief operating officer)

Ines Rudolph (administrative assistant)

4.2 Departments of the Institute

Department I: Prof. Dr. phil. nat. Dieter Bimberg

Department IIa: Prof. Dr. rer. nat. Christian Thomsen

Department IIb: Prof. Dr. rer. nat. Janina Maultzsch

Department IIc: Prof. Dr. Axel Hoffmann Prof. em. Dr.-Ing. Dr. h.c. mult. Immanuel Broser

Department III: Prof. Dr. rer. nat. Mario Dähne Prof. em. Dr.-Ing. Hans-Eckhart Gumlich

Department IV: Prof. Dr. rer. nat. Michael Kneissl Prof. Dr. rer. nat. Wolfgang Richter (retired since 01.04.2005)

4.3 Workshops

Chief operating officer

Prof. Dr. Axel Hoffmann

Mechanical workshop

Werner Kaczmarek (head)

Rainer Noethen

Wolfgang Pieper

Daniela Beiße

Marco Haupt

Electronic workshop

Norbert Lindner

Glasstechnical workshop

Norbert Zielinski

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4.4 Center of NanoPhotonics

Executive director

Prof. Dr. phil. nat. Dieter Bimberg


Prof. Dr. Udo W. Pohl

Chief technology officers

Dr. André Strittmatter (Epitaxy, Department I)

Dr. Werner Hofmann (Processing, Department I)

Technical staff

Ilona Gründler (Department I, until November 2010)

Dipl.-Krist. Kathrin Schatke (Department I)

Dipl.-Ing. Bernhard Tierock (Department I)

The Center of Nano-Photonics provides support to the institute departments by growth, processing, and analysis of materials and structures. Growth facilities are based on metal-organic vapor phase epitaxy (MOCVD), and processing facilities include dry etching, plasma deposition, and optical lithography. A second-generation furnace for the selective oxidation of AlAs to AlOx was developed, enabling precise control in the fabrication of current apertures in vertical emitters like VCSELs and single-photon emitters. For two novel kinds of vertical-cavity surface-emitting lasers a proof-of-concept was success-fully demonstrated: VCSELs with a monolithically integrated electro-optical modulator (EOM VCSELs), and microlasers with a metal-coated cavity. EOM VCSELs with precisely tuned cavities comprising up to 400 layers were grown using MOCVD, and processed to three-terminal devices. The first EOM VCSELs proved a promising dominant fraction of the modulation originating from the EO effect, a low power consumption, and open-eye operation in data transmission at 10 Gb/s. The second type of device aims at the development of nano-lasers. Lateral coating of vertical emitting pillar structures by metal allows for realizing very small modal volume, albeit accompanied by the introduction of optical losses. High-gain structures comprising optical feedback were grown using MOCVD and processed to flip-chip microlasers in cooperation with the University of Illinois. For the first time CW-lasing of such metal-coated devices at room temperature was accomplished. Output power in the µW range was achieved with devices of 2 µm diameter. The new oxidation facility enabled a processing scheme with submicron oxide apertures for efficient single-photon sources with a resonant-cavity. Single-photon emission could be proved for pulsed devices with 1 GHz repitition rate. The improved oxidation control is also employed for implementing novel VCSEL designs with reduced parasitics and bandwith well above 20 GHz.

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4.5 Affiliated Scientific Units

Collaborative Research Centre (Sfb 787) of the National Science Foundation DFG “Semiconductor Nanophotonics: Materials, Models, Devices”

Chairman

Prof. Dr. Michael Kneissl, Institute of Solid State Physics, TU Berlin

Vice chairman

Prof. Dr. Dieter Bimberg, Institute of Solid State Physics, TU Berlin

Board of directors

Prof. Dr. Andreas Knorr, Institute for Theoretical Physics, TU Berlin

Prof. Dr. Klaus Petermann, Department of Electrical Engineering, TU Berlin

Prof. Dr. Jürgen Sprekels, Weierstraß Institute for Applied Analysis and Stochastics


Dipl.-Phys. Ronny Kirste

Administrative assistant

Doreen Nitzsche In 2008 the new Collaborative Research Centre 787 (Sonderforschungsbereich 787) "Semiconductor Nanophotonics: Materials, Models, Devices" has been established. The CRC 787 also includes the Integrated Research Training Group “Semiconductor Nanophotonics” that currently has a membership of more than 65 Ph.D. students with various scientific backgrounds ranging from mathematics, physics to electrical engineering. Covering the first four years (2008-2011), the Deutsche Forschungsgemeinschaft (DFG) is supporting the CRC 787 with more than 11 million Euros. The CRC 787 combines three complementary research areas: materials, models and devices to develop novel photonic and nanophotonic devices. In the area of materials, the research activities are focusing on the material systems GaAs, InP, and GaN which are the most relevant for photonic devices. Thereby the main objectives are the investigation of new growth mechanisms as well as the fabrication of integrated nanostructures like quantum wells, quantum dots and sub-monolayer structures. Based on the development of new materials and the expertise on the physics of nanostructures we will investigate, fabricate and characterize a number of novel nanophotonic devices. These include, e.g. the development of electrically driven, quantum-dot based single photon sources for quantum cryptography, ultra-fast VCSELs for terabit data communication and high brilliance lasers from the infrared to the green spectral range. Additionally, edge emitter lasers and amplifiers for the generation and amplification of ultra-short optical pulses at highest frequencies are being developed. The interdisciplinary character and the strong educational networking between the different project partners are important features of the Integrated Research Training Group “Semiconductor Nanophotonics” which features a number of educational offerings as well as national and international educational activities like the International Nano-Optoelectronics Workshop iNOW. Another goal of the integrated graduate school is to encourage the participation of female students in the area nanophotonics and to support them in their scientific careers. The CRC 787 is comprised of a total of 16 projects

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from six institutions: The Technische Universität Berlin (Chair University), the Humboldt-Universität zu Berlin, the Otto-von-Guericke-University Magdeburg as well as the Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, the Fraunhofer Institut für Nachrichtentechnik (Heinrich-Hertz-Institute), the Weierstraß-Institute for Applied Analysis and Stochastics and the Konrad-Zuse-Zentrum für Informationstechnik.

Photo of the members of the Integrated Research Training Group “Semiconductor Nanophotonics” during the block seminar in Graal-Müritz 2010.

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Association of German Nanotechnology Centers of Competence - AGeNT-D: Arbeitsgemeinschaft der Nanotechnologie-Kompetenzzentren Deutschlands

Chairman

Prof. Dr. Dieter Bimberg

Steering committee

Dr. Andreas Baar (NMN e.V.)

Hr. Alexander Bracht (Hessen NT)

Prof. Harald Fuchs (CeNTech)

Prof. Wolfgang Heckl (Deutsches Museum)

Dr. Regine Hedderich (NanoMat)

Dr. Andreas Leson (UFS)

Prof. Frank Löffler (UPOB e.V.)

Prof. Roland Wiesendanger (INCH)

Prof. Christiane Ziegler (NanoBioNet e.V.)


Dr. Sven Rodt


Doreen Nitzsche

AGeNT-D is the German network of nanotech clusters. It comprises nine competence centres and two nanotech networks from all over Germany to cover the whole spectrum of nanotechnology. AGeNT-D promotes R&D, creates synergies and increases national and international visibility of nanotechnology in Germany.

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National Competence Center on NanoOptoelectronics of the Federal Ministry of Education and Research (bmb+f) - NanOp

Chairman

Prof. Dr. Dieter Bimberg

Steering committee

Prof. Alfred Forchel (U Würzburg)

Dr. Norbert Grote (HHI FhG)

Dr. Klaus Schulz (Sodaja Consulting)


Dr. Sven Rodt


Doreen Nitzsche

NanOp is the German national network for the application of lateral nanostructures, nanoanalytical techniques and optoelectronics. It unites 44 nationally and internationally leading research and development groups, technical and venture capital companies from Germany and the A. F. Ioffe Institute from St. Petersburg, Russia.

NanOp has two goals: to speed up research and development in the field of nanotechnologies for Optoelectronics and to transfer the results to production.

Multimedia Center for eLearning and eResearch (MuLF)

Executive director of the Center

Prof. Dr. rer. nat. Chistian Thomsen

Prof. Dr. rer. nat. Lars Knipping

Staff

Dipl.-Phys. Dirk Heinrich

Sabine Morgner

The Multimedia Center for eLearning and eResearch (MuLF) as a center in our faculty is responsible for central tasks in the area of information technology-based support of teaching. Achievements are, e.g., the information system for students (ISIS), the introduction of electronic chalk, the management system for examinations (MOSES), the electronic eprint server, or the electronic management system for the "Lange Nacht der Wissenschaften". Severeal thousand of students across the university are using these services. MuLF advises newcomers to Eteaching and offers training for the optimal use of the new media at university. Furthermore, MuLF coordinated the multimedia equipment in the lecture rooms at the university. Scientifically the center coordinates projects, like, e.g., BeLearning or LiLa, two European-community funded teaching and research projects[d1].

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4.6 External and Retired Faculty Members of the Institute

S-Prof. Dr. Norbert Esser, Institute for Analytical Sciences (ISAS) Berlin

apl. Prof. Dr. Rudolf Germer, University of Applied Sciences (FHTW) Berlin

apl. Prof. Dr. Holger Grahn, Paul-Drude-Institute (PDI) Berlin

Priv.-Doz. Dr. Thorsten U. Kampen, Fritz-Haber-Institute (FHI) Berlin

S-Prof. Dr. Bella Lake, Hahn-Meitner-Institute (HZB) Berlin

apl. Prof. Dr. Hans-Joachim Lewerenz, Hahn-Meitner-Institute (HZB) Berlin

apl. Prof. Dr. Michael Meißner, Hahn-Meitner-Institute (HZB) Berlin

apl. Prof. Dr. Norbert Nickel, Hahn-Meitner-Institute (HZB) Berlin

Priv.-Doz. Dr. Harm-Hinrich Rotermund, Fritz-Haber-Institute (FHI) Berlin

Priv.-Doz. Dr. Konrad Siemensmeyer, Hahn-Meitner-Institute (HZB) Berlin

S-Prof. Dr. Michael Steiner, Hahn-Meitner-Institute (HZB), Berlin

S-Prof. Dr. Alan Tennant, Hahn-Meitner-Institute (HZB) Berlin

apl. Prof. Dr. Wolfgang Treimer, University of Applied Sciences (TFH) Berlin

4.7 Honorary, Adjunct and Guest Professors, Humboldt Awardees and Fellows

Department I

Prof. Dr. Shun-Lien Chuang, University of Illinois, Urbana-Champaign, USA, Humboldt Awardee

Prof. Dr. Gadi Eisenstein, Technion – Israel Institute of Technology, Haifa, Israel, Humboldt Awardee

Prof. Dr. Hongbo Lan, Shandong University, Jinan, China, Chinese Scholarship

Dr. Chongyang Liu, Agency for Science, Technology and Research (A*STAR), Singapore, Humboldt Fellow

Department II

Prof. John Robertson, University of Cambridge, United Kingdom, Humboldt Awardee

Department IV

Dr. Abdul Kadir, Tata Institute of Fundamental Research, Mumbai, India

Humboldt Fellow

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5. FOREIGN GUESTS

Department I

Ismail Firat Arikan, Istanbul University, Istanbul, Turkey 01.09.2009-28.02.2010

Dr. Sergey Blokhin, A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia 08.01.-07.02.2009

Jeroen Devreese, University of Antwerp, Belgium 23.01.2009 – 06.02.2009

M.Sc. Wenjuan Fan, Tsinghua University, Beijing, China 11.01.2010-27.01.2010

Prof. Dr. Vladimir Gaysler, Russian Academy of Sciences, Novosibirsk, Russia, 15.03.2009-22.03.2009, 28.11.2009-05.12.2009, 21.04.2010-01.05.2010, 02.10.2010 -05.10.2010

Dr. Nikita Gordeev, A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia 13.04.2009-25.04.2009

Prof. Dr. Zhibiao Hao, Tsinghua University, Beijing, China 11.01.2010-14.01.2010

Dr. Leonid Karachinsky, A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia 30.08.2009-14.09.2009

M.Sc. Andrey Krasivichev, Academic Physics and Technology University, St. Petersburg, Russia, 01.11.2009-15.11.2009, 06.07.2010-02.08.2010

Prof. Dr. Yi Luo, Tsinghua University, Beijing, China 11.01.2010-14.01.2010

M.Sc. Alexey Nadtochy, A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia 01.03.2009-30.05.2009, 15.03.2010-09.05.2010, 18.10.2010-19.12.2010

Prof. Dr. Nurten Öncan, Istanbul University, Istanbul, Turkey 04.07.2009-12.07.2009

M.Sc. Alexey Payusov, A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia 30.08.2009-30.11.2009

Dr. Belal Salameh, Tafila Technical University, Tafila, Jordania 14.06.2009-14.08.2009, 06.06.2010-26.08.2010

Dr. Yumian Su, Singapore 01.01.2009-31.12.2010

Dr. Alexander Uskov, Lebebev Physical Institute, Moscow, Russia 01.10.2009-15.12.2009, 16.04.2010-30.06.2010

Türkan Üstun, University of Ankara, Turkey 15.02.2010-31.07.2010

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Alluri Avinash Varma, Indian Institute of Technology, Kanpur, India 01.10.2009-31.05.2010

Department II

Dr. Konstantin Batrakov, Belarus State University, Minsk, Belarus 01.01.-31.07.2009

Prof. Dr. Nikolaus Dietz, Georgia State University, Atlanta, USA 15.-17.06.2009, 28.05.-04.06.2010

Prof. Dr. Steven Durbin, University of Canterbury, Christchurch, New Zealand 17.-21.03.2010

Dr. Alexander Efros, U.S. Naval Research Laboratory (NRL), Washington, USA, 18.-25.01.2009

Dr. Konstantin Gartsmann, Weizmann Institute of Science, Rehovot, Israel 23.11.-07.12.2010

Dr. Alejandro Goni, Institut de Ciencia de Materials de Barcelona, Spain 05.-20.04.2009, 25.06.-06.07.2009

Franc Güell, Institut de Ciencia de Materials de Barcelona, Spain 01.-05.02.2010

Prof. Dr. Oleg Kibis, State Technical University, Novosibirsk, Russia 01.06.-31.07.2009, 01.06.-31.08.2010

Dr. Jebreel Koshman, Al-Hussein Bin Talal University, Amman, Jordan 26.02.-31.03.2009, 10.06.-10.09.2010

Dr. Polina Kuzhir, Belarusian State University, Minsk, Belarus 01.-30.06.2009

Prof. Dr. Sergey Maksimenko, Belarusian State University, Minsk, Belarus 01.06.-31.07.2009, 01.-31.12.2009, 01.-30.06.2010

Prof. Dr. Bruno K. Meyer, Justus-Liebig-Universität Gießen, Germany 20.-22.02.2009

Prof. Dr. Matthew Philips, University of Technology, Sydney, Australia 12.-17.06.2009, 21.-25.09.2009, 29.06.-04.07.2010

Dr. Anna Rodina, Ioffe Physical Technical Institute, St. Petersburg, Russia 13.-25.01.2009, 10.-23.08.2009, 14.-22.03.2010, 31.07.-28.08.2010

Prof. Dr. Zlatko Sitar, North Carolina State University, Raleigh, USA 10.-13.11.2009

Dr. Gregory Slepyan, Belarusn State University, Minsk, Belarus 01.06.-31.07.2009

Prof. Dr. Tadeusz Suski, Unipress, Warschau, Poland 18.-20.05.2009

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Dr. Filip Tuomisto, Helsinki University of Technology, Finland 14.-20.01.2009

Jielei Wang, Department of Electronics and Engineering, Georgia State University, Atlanta USA 16.-31.05.2010

Department III

Frédérick Delgrange, ISEN, Lille, France Mai-September 2010

Dr. Ph. Ebert, Forschungszentrum Jülich September 2009, November 2009, April 2010, June 2010, November 2010

Dr. F. Grosse, Paul-Drude-Institut Berlin September 2010

Prof. Dr. C. K. Shih, University of Texas at Austin, USA May 2009

Prof. Dr. A. Smith, Ohio University, USA June 2010

Dr. M. Ternes, Max-Planck-Institut für Festkörperphysik, Stuttgart February 2009

Dr. R. Timm, Lund University, Sweden Dezember 2010

Prof. Dr. S. Tsukamoto, Anan National College of Technology, Tokushima, Japan August 2010

Department IV

Dipl. Phys. Steven Albert, Univ. Polytec. Madrid, Spain 03.-08.10.2010

Dr. Ryan Banal, National Institute of Genetics, Kawakami Laboratory, Kyoto Daigaku, Japan, 13.-16.06.2009

Prof. Dr. Arnab Bhattacharya, Tata Institute of Fundamental Research, Mumbai, India, 01.-18.06.2009, 24.-30.06.2010

Dr. Sandhya Chandola, The University of Dublin, Trinity College, Dublin, Ireland, 01.01.-31.12.2009

Prof. Dr. Weng Chow, Sandia National Laboratories, Albuquerque, New Mexico, USA, 06.10.-07.11.2009, 26.10.-20.11.2010

Dipl.-Phys. Franscesco Ivaldi, Polish Academy of Science, Warzawa, Poland, 13.- 17.07.2009, 03.- 08.10.2010

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Dr. Abdul Kadir, Tata Institute of Fundamental Research, Mumbai, India, 24.05.-15.07.2009, 10.09.-31.12.2010

Dr. Slawomir Kret, Polish Academy of Science, Warzawa, Poland 13.-17.07.2009

Dr. Michelle Moram, University of Cambridge, Cambridge, UK 02.-06.06.2009

Prof. Dr. Dimitra Papadimitriou, Institute of Physics, National Technical University of Athens, Greece 11.-22.02.2009, 03.-28.08.2009, 14.04.-08.05.2010, 04.07.-31.08.2010

Dr. Joachim Piprek, NUSOD Institute LLC, Newark, USA, 08.-14.11.2009, 19.-23.04.2010

Prof. Dr. O. Pulci, Università degli Studi di Roma II ‘Tor Vergata’, Roma, Italy 19.08.-04.09.2010

Dipl. Phys. Linda Riele, Università degli Studi di Roma II ‘Tor Vergata’, Roma, Italy 01.-22.01.2010, 16.08.-21.08.2010, 03.-08.10.2010

Dr. Eugen, Speiser, Università degli Studi di Roma II ‘Tor Vergata’, Roma, Italy 09.-16.02. 2009

Dr. Tomohiro Yamaguchi, National Institute of Genetics, Kawakami Laboratory, Kyoto Daigaku, Japan 13.-16.06.2009

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6. PARTICIPATION IN COMMITEES

6.1 Program and Advisory Committee

Dieter Bimberg

Member of the International Advisory and Program Committee of the “LEOS-Winter Topical Meeting”, Innsbruck, Austria, January, 12 – 14, 2009

Member of the International Advisory Committee of the “17th International Symposium Nanostructures: Physics and Technology”, Minsk, Belarus, June 22 – 26, 2009

Member of the International Advisory and Program Committee of the “12th International Conference on the Formation of Semiconductor Interfaces” (ICFSI-12), Weimar, Germany, July 5 – 10, 2009

Chair of the Program Committee of the “International Nano-Optoelectronics Workshop” (iNOW), Stockholm, Swedn, Berlin, Germany, August 2-15, 2009

Chair of the Program Committee of “Nanotech Europe 2009”, Berlin, Germany, September 28 – 30, 2009

Member of the Program Committee of the “Collaborative Conference on Interacting Nanostructures” (CCIN), San Diego, CA, USA, November 9 – 13, 2009

Member of the Program Committee of the Symposium “Semiconductor Lasers and Laser Dynamics Conference” within Photonics Europe, Brussels, Belgium, April 12 – 16, 2010

Member of the International Advisory Committee of the “12th International Ceramics Congress” (CIMTEC 2010), Montecatini Terme, Italy, June 6 – 11, 2010

Member of the International Advisory Committee of the “18th International Symposium Nanostructures: Physics and Technology”, St. Petersburg Russian Federation, June 21 – 26, 2010

Member of the Program Committee of “The 2010 Villa Conference on Interaction among Nanostructures” (VCIAN-2010). Santorini, Greece, June 21 – 27, 2010

Member of the International Advisory Committee of the “International Conference on Superlattices, Nanostructures and Nanodevices” (ICSNN-2010), Beijing, China, July 18 – August 3, 2010

Member of the Program Committee of the “International Nano-Optoelectronics Workshop” (iNOW), Beijing, China, August 1 – 15, 2010

Axel Hoffmann

Member of the Program Committee of the “SPIE Photonics West”, San Jose, California, USA, January 2009

Member of Member of the Program Committee of the “Frühjahrstagung der Deutschen Physikalischen Gesellschaft (DPG)”, Berlin, Germany, March 2009

Chairman of the “E-MRS Spring Meeting 2009” (E-MRS 2009), Strasbourg, France, May 2009

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Member of the Organization Committee of the Int. Nano-Optoelectronical Workshop (INOW), Berlin, Germany, July 2009

Member of the Program Committee of the “SPIE Photonics West”, San Francisco, California, USA, January 2010

Member of the Intern. Advisory Committee, PLMCN X, X. International Conference on Physics of Light-Matter Coupling in Nanostructures, Cuernavaca, Mexico, February 2010

Member of the Program Committee of the “Frühjahrstagung der Deutschen Physikalischen Gesellschaft (DPG)”, Berlin, Germany, March 2010

Member of the Advisory Committee of the “8’th International Symposium on Semiconductor Light Emitting Devices (ISSLED)”, Beijing, China, May 2010

Member of the Program Committee of the “ISGN 3”, Montpellier, France, July 2010

Member of the Advisory Committee of the “International Workshop on Nitride Semiconductors (IWN)”, Tempa, USA, September 2010

Michael Kneissl

Member of the Program Committee of “Novel In-Plane Semiconductor Lasers VIII”, San Francisco, USA, January 2009

Member of the local Organizing Committee of the “International Nano-Optoelectronics Workshop (i-NOW 2009)”, Berlin, August 2009

Member of the Organizing Committee of the E-MRS 2009 Fall Meeting Symposium on ”InN materials and alloys”, Warsaw, Poland, September 2009

Conference chair of the “DGKK 2009”, Epitaxy Workshop of “The German Association for Crystal Growth” (DGKK), Berlin, December 2009

Member of the Program Committee of “Novel In-Plane Semiconductor Lasers IX”, San Francisco, USA, January 2010

Member of the Program Committee of the “International Workshop on Nitride semiconductors” (IWN 2010), Tampa, Florida, USA, September 2010

Janina Maultzsch

Member of the organizing committee: “Electronic Properties of Novel Materials”, Kirchberg, Austria, 07.-14.03.2009

Member of the organizing committee: “Electronic Properties of Novel Materials”, Kirchberg, Austria, 06.-13.03.2010

Markus Pristovsek

Member of the Program Committee of "SemiconNano 2009", Tokushima, Japan, August 2009

Christian Thomsen

Organiser and member of the committee: “Electronic Properties of Novel Materials”, Kirchberg, Austria, 07.-14.03.2009

Organiser and member of the committee: “Electronic Properties of Novel Materials”, Kirchberg, Austria, 06.-13.03.2010

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6.2 Editorial Duties / Boards of Institutes and Companies

Dieter Bimberg

International Editorial Advisory Board "Opto-Electronics Review" (O-ER) Warsaw, Poland

Editorial Board, IET Optoelectronics Journal, U.K.

Editorial Board, “Research Letters in Physics”, USA/Egypt

International Board of Editors, “Semiconductor News”, Pakistan

Assoicate Editor, IEEE Photonics Journal, Fort Collins, Colorado, USA

Chairman Scientific Advisory Board, VI Systems GmbH, Berlin, Germany

Chairman of the Board, PBC Lasers GmbH, Berlin, Germany

Member of the International Advisory Board of “Skolkovo Foundation”

Member of the Board “Technopark Skolkovo Ltd.”

Axel Hoffmann

Editorial Board of “physica status solidi (c)”, WILEY-VCH, Weinheim, Germany

Michael Kneissl

Guest Editor of a special issue on “Nonpolar Nitrides” to be published in Semiconductor Science & Technology, IOP Publishing

Guest editor for the Proceedings of the “International Workshop on Nitride semiconductors”´(IWN 2010), Physica Status Solidi, Wiley

Member or the Board of the Zentraleinrichtung Elektronenmikroskopie “ZELMI”

Christian Thomsen

Editor physica status solidi

Editor Solid State Communications

Physica status solidi – Rapid Research Letters

IWEPNM 2009, 23rd International Winterschool on Electronic Properties of Novel Materials: Molecular Nanostructures

IWEPNM 2010, 24th International Winterschool on Electronic Properties of Novel Materials: Molecular Nanostructures

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7. TEACHING

Internal faculty members

Lab Course in Methods of Applied Physics I and II D. Bimberg

Lab Course in Advanced Experimental Physics D. Bimberg, M. Dähne, A. Hoffmann, M. Kneissl, J. Maultzsch, C. Thomsen

Applied Physics I + II D. Bimberg, A. Hoffmann, W. Hofmann, U.W. Pohl, M. Weyers

Seminar on Photonics: Materials, Devices, Systems D. Bimberg, A. Hoffmann, U.W. Pohl, A. Strittmatter

Selected Topics of Solid State Physics D. Bimberg, C. Thomsen

Semiconductor Epitaxy U. W. Pohl Experimental Physics I, II M. Dähne

Experimental Physics V – Introduction to Solid State Physics M. Dähne

Seminar on Surfaces, Interfaces and Nanostructures M. Dähne, H. Eisele, J. Grabowski, L. Ivanova, A. Lenz

Experimental Methods M. Dähne (organizator)

Applied Physics I: LEED H. Eisele

Advanced Lab Course: STM A. Lenz

Exercises for Experimental Physics V L. Ivanova, J. Grabowski (2009/10) ; C. Prohl, M. Franz (2010/11)

Further Education: Instrumental Analytic, Course 6 M. Dähne, M. Franz, C. Prohl

Macroscopic Quantum Phenomena in Solid State Physics A. Hoffmann

Modern Methods of Solid State Physics A. Hoffmann

Solid State Physics I + II M. Kneissl, P. Vogt, M. Pristovsek, N. Nickel, H.-J. Lewerenz

Lab course in Solid State Physics I + II M. Kneissl, P. Vogt

Seminar series “Physics of Semiconductor Interfaces and Heterostructures” M. Kneissl, P.Vogt, M. Pristovsek

Seminar series “Modern Concepts in Optoelectronics” M. Kneissl, M. Pristovsek

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Lab Course in Advanced Experimental Physics M. Kneissl, D. Bimberg, M. Dähne, C. Thomsen

Group Theory in Solid State Physics J. Maultzsch

Introduction to Physics for Engineering Students I + II C. Thomsen

Special Topics in Physics for Engineering Students C. Thomsen

Special Topics in Carbon Nanotubes and Graphene C. Thomsen & J. Maultzsch

External faculty members

Ultrasonics and Phonons R. Germer

Introduction to classical physics for engineers H. Grahn

Organic Semiconductors: performance, production, applications T. Kampen

Photonic Processes in nanoscience H.-J. Lewerenz

Surface Physical Research on Energy Converted Semiconductor Structures H.-J. Lewerenz

Hydrogen in Solid States N. Nickel

Neutrons as an Efficient Tool to Investigate Condensed Matter K. Siemensmeyer, B. Lake

Neutron Scattering I K. Siemensmeyer, B. Lake

31st Berlin School on Neutron Scattering A. Tennant, B. Lake

Advanced Magnetism A. Tennant

Selective Sections of Neutron Scattering A. Tennant

Introduction to Physics for Engineering Students C. Thomsen, H. Grahn

Introduction to X-ray- and Neutron Computed Tomography W. Treimer

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8. PATENTS

Speicherzelle und Verfahren zum Speichern von Daten Memory cell, and the method for storing data USA Patentanmeldung AZ: 12/518,223 (08.06.2009) Koreanische Patentanmeldung AZ: 10-2009-7014186 (07.07.2009) Japanische Patentanmeldung AZ: 2010-512012 (16.04.2010) Martin Geller, Andreas Marent, Dieter Bimberg

Tuning von VCSEL-Kavitäten und Quantenpunktresonanzen durch extern erzeugte Verspannung mittels piezoelektrischer Aktuatoren US Patentanmeldung Nr. 12/891,437 (27.09.2010) Andrei Schliwa, Erik Stock, Dieter Bimberg

Photonenpaarquelle und Verfahren zu deren Herstellung Internationale Patentanmeldung Nr. PCT/DE 2009/001025 (20.07.2009) Erteilung deutsches Patent: Nr. 10 2008 036 400.2-33 (21.01.2010) Momme Winkelnkemper, Andrei Schliwa, Dieter Bimberg

Method for fabricating large area and highly ordered quantum dot array USA Patentanmeldung AZ: 12/662,661 (27.04.2010) Hongbo Lan, Udo W. Pohl, Dieter Bimberg

Speicherzelle auf Basis von Nanostrukturen aus Verbindungshalbleitern USA Patentanmeldung AZ: US 12/970,744 (16.12.2010) Andreas Marent, Martin Geller, Dieter Bimberg, Tobias Nowozin

P-Kontakt und Leuchtdiode für den ultravioletten Spektralbereich

PCT/EP2010/060333 Prof. Dr. M. Kneissl, PD Dr. M. Weyers, Dr. Sven Einfeldt, Dr. Hernan Rodriguez

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41

9. SCIENTIFIC ACTIVITIES

9.1 Department I

Prof. Dr. phil. nat. Dieter Bimberg

9.1.1 Staff

Secretary

Ulrike Grupe

Technical Staff

Jörg Döhring

Ilona Gründler (until 30.11.2010)

Dipl.-Ing. Bernd Ludwig (until 30.06.2010)

Dipl.-Krist. Kathrin Schatke

Dipl.-Ing. Bernhard Tierock

Permanent Guest Scientists

Prof. Dr. Jürgen Christen

Prof. Dr. Shun-Lien Chuang

Priv.-Doz. Dr. Armin Dadgar

Prof. Dr. Gadi Eisenstein

Prof. Dr. Wolfgang Gehlhoff

Prof. Dr. Alois Krost

Prof. Dr. Nicolai N. Ledentsov

Dr. Vitali A. Shchukin

Principal Scientists

Prof. Dr. Udo W. Pohl

Dr. Werner Hofmann

Dr. André Strittmatter

Senior Scientists

Dr. Vladimir Kalosha

Dr. Thorsten Kettler (until 31.10.2010)

Dr. Anatol Lochmann (until 31.10.2010)

Dr. Andreas Marent

Dr. Alex Mutig (until 31.10.2010)

Dr. Konstantin Pötschke (until 30.09.2009)

Dr. Sven Rodt

Dr. Andrei Schliwa (until 31.08.2010)

Dr. Erik Stock

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Dr. Till Warming (until 31.12.2009)

Dr. Momme Winkelnkemper (until 31.12.2009) PhD Candidates

Dipl.-Phys. Dejan Arsenijević

Dipl.-Phys. Gerrit Fiol

Dipl.-Phys. Tim Germann

Dipl.-Phys. Ole Hitzemann

Dipl.-Phys. Gerald Hönig

Dipl.-Phys. Thorsten Kettler (until 04.05.2010)

Dipl.-Phys. Anatol Lochmann (until 30.04.2010)

Dipl.-Phys. Andreas Marent (until 22.10.2010)

Dipl.-Phys. Christian Meuer

Dipl.-Phys. Philip Moser

Dipl.-Phys. Alex Mutig (until 15.07.2010)

Dipl.-Phys. Tobias Nowozin

Dipl.-Phys. Irina Ostapenko

Dipl.-Phys. Kristijan Posilovic

Dipl.-Phys. Konstantin Pötschke (until 27.02.2009)

Dipl.-Phys. Holger Schmeckebier

Dipl.-Phys. Jan-Hindrik Schulze

Dipl.-Phys. Erik Stock (until 03.12.2010)

Dipl.-Phys. Gernot Stracke

Dipl.-Phys. Mirko Stubenrauch

Dipl.-Phys. Waldemar Unrau

Dipl.-Phys. Till Warming (until 20.02.2009)

Diploma Students

Dejan Arsenijević (until 16.02.2009)

Alexander Dreismann

Johannes Gelze (28.07.2009)

Alexander Glacki

Annika Högner (until 22.12.2010)

Gerald Hönig (until16.10.2009)

Gunter Larisch

Gang Lou (until 18.10.2009)

Benjamin Maier (until 22.10.2010)

Murat Öztürk

Holger Schmeckebier (until 19.06.2009)

Daniel Seidlitz (until 15.01.2010)

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Jan Amaru Töfflinger (until 18.03.2010)

Peter Benedikt Weber (until 03.06.2009)

Philip Wolf (until 08.07.2010)

Master Students

Leo Bonato

Alissa Wiengarten

Martin Winterfeldt

Bachelor Students

Moritz Kleinert (until 14.06.2010)

Luzy Krüger

Peter Schneider

Tristan Visentin (until 07.10.2010)

Martin Winterfeldt (until 02.12.2009)

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9.1.2 Summary of Activities

The activities of the department are grouped into five mutually connected research areas with complementary objectives:

- Nanostructures: Growth and Physics,

- Surface Emitters: VCSELs, Single/Entangled Photon Emitters, Silicon Photonics,

- Edge Emitters: High Frequency Lasers and Amplifiers, High Brightness Lasers,

- Nanoflash Memories,

- Magnetic Resonance.

A few of the highlights of the last two years are emphasized in the summary below. For an exhaustive overview on our activities see the list of publications, which can be easily retrieved in the internet.

A quantitatively correct theoretical description of the electronic structure of quantum dots, including exchange and correlation effects to describe the excitonic fine-structure splitting, on surfaces of varying orientation in arsenides and nitrides, presents a major theoretical challenge. Using the configuration interaction approach in conjunction with eight-band k·p theory, including first and second order piezoelectric fields, we predict that the confinement potential of InAs/GaAs quantum dots grown on (111) planes is not lowered by piezoelectric effects, in contrast to such quantum dots grown on (001) planes. The piezoelectric fields for these two configurations are shown in figure 1. Thus the excitonic fine structure splitting vanishes for InAs QDs grown on GaAs (111)-planes as long as no additional symmetry lowering effects are present. Micro-PL experiments confirm the predictions.

Figure 1: Piezoelectric potentials for lens-shaped InAs/GaAs quantum dots grown on GaAs(111)B and GaAs(001) substrates.

Surprisingly the excitonic fine-structure splitting was observed in Micro-PL experiments on GaN/AlN quantum dots also. Here it reaches huge values of up to 7 meV. The size dependence of the FSS is found to be inverse to that observed for InAs/GaAs QDs. A shape/strain anisotropy is revealed as being the origin of the large FSS for small GaN/AlN QDs.

Thus InAs/GaAs QDs grown on (111) surfaces are identified as ideal sources of entangled photon pairs. GaN/AlN QDs emitting in the UV might enable the realization of room-temperature single-q-bit emitters for quantum cryptography and communication.

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The sensitivities of our µ-photoluminescence excitation (µ-PLE) and µ-photoluminescence (µPL) spectroscopy set-ups were largely improved, such that by a combination of both methods for the first time ever the energy distances between single hole levels of single InGaAs QDs could be experimentally determined. Appreciable heavy-hole light-hole coupling was found to be decisive to explain the observed nonzero h1-h2-splitting. A number of trion transitions forbidden in the virtual crystal approximation (VCA) are experimentally observed. Describing the atomic distribution in a QD by a much more realistic granulated crystal model (Fig. 2) strict selection rules of the VCA are lifted and the experimental results are explained.

Figure 2: Representations of an InAs/GaAs QD in the virtual crystal approximation and in the granulated crystal model.

Break-throughs in devices often happen when creative intelligence and time is invested in the design of improved or novel device technologies or set-ups for their characterization. Controlled fabrication of single and multiple oxide apertures is of fundamental importance for the performance of vertical light emitters, VCSELs and single/entangled photon emitters. We put into operation at the Center of NanoPhotonics a second generation and largely improved set-ups for fabricating such oxide apertures, including in-situ control, and immediately recognized the merits of better process control by a multitude of improved device parameters.

Characterizing all of the 5000+ surface emitters on a 2 inch wafer is hardly possible, if no automatic procedure is used. We constructed a fully software controlled device mapper, who delivers after about 20 hours the essential I-V and I-L characteristics, including derived quantities like threshold current for all of the devices of a wafer. Thus selection of the “best” is possible.

High frequencies and bit rates up to elevated temperatures like 85°C and sometimes 120°C are essential for applications of VCSELs in data communication. Our own work focused on the two wavelengths, 850 nm and 980 nm, presently competing with each other all over the world, becoming the dominant one for systems ranging from a few cm to about 100 m. For 850 nm VCSELs we reported record 40 Gbit/s error-free transmission with a bit error rate (BER) smaller than 10-12 (Fig. 3). Introduction of multimode apertures leads to another record: 25 Gbit/s error-free transmission at 85°C for 980 nm. Detailed analysis of the various fundamental physical parameters that limit high bit-rate performance like relaxation resonance frequency, damping factor, D-factor, K-factor, parasitic cut-off frequency, and others indicate that further design advances will enable operation at still higher temperatures and bit rates. 22 Gbit/s operation of long wavelength 1.55 µm VCSELs was additionally demonstrated in collaboration with the group of Professor Amann from TU Munich.

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Figure 3: Bit-error rate measurement for a 850 nm VCSEL at 75 °C.

Based on our design experience of VCSELS we developed a new generation of single-q-bit emitters on demand based on resonant cavity LEDs using an oxide aperture confining the current to a single InAs quantum dot. The Purcell-effect enhances the emission intensity, reduces the exciton lifetime and enables the first experimental demonstration of a modulation frequency of 1 GHz. Improved high frequency design of the devices (Fig. 4) will lead to still higher cut-off frequencies.

Figure 4: Schematic view of our new high-frequency design for single-photon emitters.

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The footprint of a VCSEL is only about 1% of that of edge emitting lasers. Yet it is too large for future heterogeneous integration of light emitters with silicon ICs, in particular for parallel optical links operating at bit rates larger than 1 Tbit/s with minimum power consumption. A radically different design approach for surface emitters is based on metal cavities (see Fig. 5), occupying a surface area of about 1% of that of a VCSEL. Integrated modeling, growth, processing and characterization of such devices were pursued together with the group of Professor S.-L. Chuang from U.I. Urbana, and led to immediate success. For the first time room-temperature operation of such devices, having a diameter of 2 µm, was achieved resulting in an output power of close to 8 µW. The devices were flip-chip mounted on Si-substrates, showing an extremely low thermal impedance. Such devices might present in the future a cornerstone of Si-photonics.

Figure 5: Schematics of our metal-cavity microlaser. The fabricated device has an active region of multiple (14) quantum wells sandwiched between a silver metal reflector on p-doped GaAs/AlGaAs layers and an n-doped DBR (flip-chip bonded upside down on a gold coated silicon substrate). The device is surrounded by silicon nitride and silver on the sidewalls to form a closed optical microcavity. The GaAs substrate below the DBR/InGaP (etch stop layer) has been removed, and the physical size is 2.0 µm in diameter and 2.5 µm in total thickness.

QD-based mode-locked lasers driven under optimized conditions still show pulse widths being much larger than the Fourier-transform limit given by the Gaussian broadened gain width of such lasers. A detailed investigation of the chirp showed the broadening to be essentially caused by a linearly chirped emission, excluding a number of different exotic explanations found in the literature. We compensated the chirp and obtained 40 GHz pulses of only 0.7 ps width. By multiplexing finally a pulse comb of 0.7 ps pulses at 160 GHz was demonstrated (see Fig. 6).

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Figure 6: Autocorrelation measurement (left) and retrieved pulse comb (right) of the hybrid mode-locked device demonstrating a pulse comb of 0.7 ps pulses at 160 GHz.

Previous investigations of QD-based semiconductor optical amplifiers (SOAs) showed saturated linear chip gain of up to 35 dB at 1.3 µm. Many future all-optical networks will be based on the operation of optical devices at high frequencies in a nonlinear range. Wavelength conversion presents a particular challenge. We demonstrated for the first time wavelength conversion by 10 nm up to 80 Gbit/s of return-to-zero (RZ) on-off-keying (OOK) signals with a BER smaller than 10-9 using a QD SOA in combination with a delay interferometer (DI). Figure 7 shows the BER measurement and the corresponding converted eye diagram of a pseudo-random binary sequence (PRBS) 231-1 RZ OOK data signal at 80 Gbit/s representing successful conversion of 80 Gbit/s OOK data signals.

Fig. 7: (a) Eye diagram of the converted 80 Gbit/s data signal at 1320 nm after the DI showing an extinction ratio of 9.3 dB. (b) Bit error rate versus received power for 80 Gbit/s RZ-OOK wavelength conversion from 1310 nm to 1320 nm (FSR: free spectral range).

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Increasing output power and brightness of edge emitting semiconductor lasers (EELs) to values far above presently obtained ones is challenging, since known commercial concepts are not believed to have such potential, and rewarding, since many important scientific and commercial applications, like scribing or cutting, could be covered by inexpensive and energy efficient light sources. We have designed, fabricated and measured the performance of two novel design types of EELs, photonic-band-crystal lasers (PBC) and tilted-wave lasers (TWL), with unconventional waveguides and lateral arrays thereof. Both concepts are patented. The PBC structure which contains an embedded higher-order mode filter allows us to expand the ground mode across the entire waveguide. An almost symmetric far field of 7° results with more than 2 W cw output power and a M2-value of 1.5. The brightness is 1x108

Wsr-1cm-2, more than one order of magnitude larger than reported, yet. Under pulsed conditions the brightness and peak power are still four times larger. First modeling results indicate the potential of coherent coupling of stripes, as shown in figure 8 for three stripes.

Figure 8: PBC laser stripes that show coherent coupling of three stripes for small lateral distances.

The „New Scientist“ hailed results of our nanoflash research program (based on our own patents) as the potential “holy grail” of future semiconductor nano-memories. 106 years of hole storage time was extrapolated for GaSb/AlAs QD-memory structures (see Fig. 9) from our present results of about 2 s presently obtained for InAs/AlGaAs-QD hole memories. Write-times much below 1 ns are expected, governed by the ultrafast relaxation time of holes, that are independent of the storage time of the carriers. Six nanoseconds, yet controlled by device parasitic, are observed.

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Figure 9: Estimated storage times for different QD systems as a function of localization energy.

EPR activities

Diluted magnetic semiconductors (MS) that exhibit ferromagnetism at room temperature are essential for the development of semiconductor spintronics. According to theoretical predictions transition metal (TM)-doped AIIBIVCV

2 chalcopyrite and the II-VI semiconductor ZnO are promising compounds of such applications. The magnetic resonance studies of native defects and their transition energies, investigations of isolated TM on the two different cation lattice sites in the ternary compounds, on exchanged coupled pairs as well as the interaction of TMs with native defects were critically analysed and compared with theoretical predictions. New results about the incorporation of TMs in ZnO nanowires and colloidal ZnO nanocrystals (NCs) were obtained. We proved that the TM-doped colloidal ZnO nanocrystals exhibit a core-shell structure revealed by the relative intensity of the EPR spectra and by the performed surface modifications. The incorporation of Li on Zn sites in ZnO NCs was demonstrated by the detection both of the axial and non-axial Li defects. The interest of Li as dopant in ZnO is based on both its possible ability to act as a p-dopant in ZnO, as well as on the fact that Li is a major impurity in ZnO growth. Besides, new electrically-detected electron paramagnetic resonance (EDEPR) and optically-detected magnetic resonance (ODMR) results of impurity centres in nanostructures inserted in silicon microcavities were received.

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9.1.3 Publications

a) Nanostructures: Growth and Physics 1. Few-particle energies versus geometry and composition of InxGa1-xAs/GaAs self-

organized quantum dots A. Schliwa, M. Winkelnkemper, and D. Bimberg Physical Review B 79, 075443 (2009)

2. Hole-hole and electron-hole exchange interactions in single InAs/GaAs quantum dots T. Warming, E. Siebert, A. Schliwa, E. Stock, R. Zimmermann, and D. Bimberg Physical Review B 79, 125316 (2009)

3. In(Ga)As/GaAs quantum dots grown on a (111) surface as ideal sources of entangled photon pairs A. Schliwa, M. Winkelnkemper, A. Lochmann, E. Stock, and D. Bimberg Physical Review B 80, 161307 (2009)

4. InGaAs quantum dots coupled to a reservoir of nonequilibrium free carriers J. Gomis-Bresco, S. Dommers, V.V. Temnov, U. Woggon, J. Martinez-Pastor, M. Laemmlin, D. Bimberg IEEE Journal of Quantum Electronics 45 (9), 1121 (2009)

5. Limits of In(Ga)As/GaAs quantum dot growth A. Lenz, H. Eisele, R. Timm, L. Ivanova, R.L. Sellin, H.Y. Liu, M. Hopkinson, U.W. Pohl, D. Bimberg, and M. Dähne Phys. Stat. Sol. (b) 246, 717 (2009)

6. Quantenpunkte: Design-Atome in Halbleitern S. Rodt, D. Bimberg Welt der Physik 7118 (2009)

7. Quantenpunkte: Technische Anwendungen der «künstlichen Atome» S. Rodt, D. Bimberg Welt der Physik 7122 (2009)

8. Quantum dots for single- and entangled-photon emitters D. Bimberg, E. Stock, A. Lochmann, A. Schliwa IEEE Photonics Journal 1 (1), 57 (2009)

9. Self-assembled quantum dots with tunable thickness of the wetting layer: Role of vertical confinement on interlevel spacing L. Wang, V. Křápek, F. Ding, F. Horton, A. Schliwa, D. Bimberg, A. Rastelli, and O.G. Schmidt Physical Review B 80, 85309 (2009)

10. Spectroscopic access to single-hole energies in InAs/GaAs quantum dots E. Siebert, T. Warming, A. Schliwa, E. Stock, M. Winkelnkemper, S. Rodt, and D. Bimberg Physical Review B 79, 205321 (2009)

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11. A tribute to Zhores Ivanovitch Alferov, a pioneer who changed our way of daily life D. Bimberg Semiconductor Science Technology 26, 010301 (2010)

12. Atomic structure of buried InAs sub-monolayer depositions in GaAs A. Lenz, H. Eisele, J. Becker, L. Ivanova, E. Lenz, F. Luckert, K. Pötschke, A. Strittmatter, U.W. Pohl, D. Bimberg, and M. Dähne Appl. Phys. Express 3, 105602 (2010)

13. Band parameters and strain effects in ZnO and group-III nitrides Q. Yan, P. Rinke, M.Winkelnkemper, A Qteish, D. Bimberg , M. Scheffler, and C.G. Van deWalle Semiconductor Science Technology 26, 014037 (2010)

14. Confined states of individual type-II GaSb/GaAs quantum rings studied by cross-sectional scanning tunneling spectroscopy R. Timm, H. Eisele, A. Lenz, L. Ivanova, V. Vossebürger, T. Warming, D. Bimberg, I. Farrer, D.A. Ritchie, and M. Dähne NanoLetters 10, 3972 (2010)

15. Effect of the shape of InAs nanostructures on the characteristics of InP-based buried heterostructure semiconductor optical amplifiers D. Franke, J. Kreissl, W. Rehbein, F. Wenning, H. Kuenzel, U.W. Pohl, and D. Bimberg Appl. Phys. Express 4, 014101 (2010)

16. Exciton fine-structure splitting in GaN/AlN quantum dots C. Kindel, S. Kako, T. Kawano, H. Oishi, Y. Arakawa, G. Hönig, M. Winkelnkemper, A. Schliwa, A. Hoffmann, and D. Bimberg Physical Review B 81, 241309 (2010)

17. Experimental investigation and modeling of the fine structure splitting of neutral excitons in strain-free GaAs/AlxGa1-xAs quantum dots J.D. Plumhof, V. Křápek, L. Wang, A. Schliwa, D. Bimberg, A. Rastelli, and O.G. Schmidt Physical Review B 81, 121309 (2010)

18. In(Ga)As quantum dots grown on GaAs(111) substrates for entangled photons pairs I.A. Ostapenko, E. Stock, T. Warming, S. Rodt, A. Schliwa, M. Öztürk, J.A. Töfflinger, A. Lochmann, D. Bimberg, A.I. Toropov, S.A. Moshchenko, D.V. Dmitriev, V A. Haisler Journal of Physics: Conf. Ser. (Robert A Taylor, Ed.) 245, 012003 (2010)

19. Large internal dipole moment in InGaN/GaN quantum dots I. A. Ostapenko, G. Hönig, C. Kindel, S. Rodt, A. Strittmatter, A. Hoffmann, D. Bimberg Appl. Phys. Lett. 97, 063103 (2010)

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20. Nachruf auf Ulrich M. Gösele D. Bimberg, O. Engström, H. Föll, F. Spaepen, K. Urban, E. Weber Physik Journal 9, 48 (2010)

21. Optical imaging of electrical carrier injection into individual InAs quantum dots A. Baumgartner, E. Stock, A. Patanè, L. Eaves, M. Henini, and D. Bimberg Physical Review Letters 105, 257401 (2010)

22. Photon statistics of a single quantum dot in a microcavity Y. Su, M. Richter, A. Knorr, D. Bimberg, and A. Carmele Physica Status Solidi - Rapid Research Letters 4, 289 (2010)

23. Self-organized quantum dots for single photon emitters E. Stock Proc. of 18th Int. Symp. “Nanostructures: Physics and Technology”, St. Petersburg, Russia, June 2010 (Zh.I. Alferov, L. Esaki, Eds.), 359 (2010)

24. Semiconductor quantum dots: Same, same, but different D. Bimberg International Symposium Semiconductor Heterostructures:, St. Petersburg, March 2010 (2010)

25. Single photon sources based on semiconductor quantum dots D. Bimberg, E. Stock Photonics Society Winter Topicals Meeting Series (WTM), 2010 IEEE , 141 (2010)

26. Single-photon emission from InGaAs quantum dots grown on (111) GaAs E. Stock, T. Warming, I. Ostapenko, S. Rodt, A. Schliwa, J.A. Töfflinger, A. Lochmann, A.I. Toropov, S.A. Moshchenko, D.V. Dmitriev, V.A. Haisler, and D. Bimberg Appl. Phys. Lett. 96, 093112 (2010)

27. Theory of single quantum dot lasers: Pauli-blocking-enhanced anti-bunching Y. Su, A. Carmele, M. Richter, K. Lüdge, E. Schöll, D. Bimberg and A. Knorr Semiconductor Science Technology 26 (1), 014015 (2010)

28. Time-resolved amplified spontaneous emission in quantum dots J. Gomis-Bresco, S. Dommers-Völkel, O. Schöps, Y. Kaptan, O. Dyatlova, D. Bimberg, and U. Woggon Appl. Phys. Lett. 97, 251106 (2010)

b) Surface Emitters: VCSELs, Single Entangled Photon Emitters, Silicon Photonics

29. 120°C 20 Gbit/s operation of 980 nm VCSEL based on sub-monolayer growth F. Hopfer, A. Mutig, G. Fiol, P. Moser, D. Arsenijević, V.A. Shchukin, N.N. Ledentsov, S.S. Mikhrin, I.L. Krestnikov, D.A. Livshits, A.R. Kovsh, M. Kuntz, and D. Bimberg Proc. of SPIE: Vertical-Cavity Surface-Emitting Lasers XIII (K. D. Choquette, Chun Le, Eds.) 7229, 710 (2009)

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30. 20 Gbit/s error free transmission with ~850 nm GaAs-based vertical cavity surface emitting lasers (VCSELs) containing InAs-GaAs submonolayer quantum dot insertions J.A. Lott, V.A. Shchukin, N.N. Ledentsov, A. Stinz, F. Hopfer, A. Mutig, G. Fiol, D. Bimberg, S.A. Blokhin, L.Y. Karachinsky, I.I. Novikov, M.V. Maximov, N.D. Zakharov, and P. Werner Proc. of SPIE: Physics and Simulation of Optoelectronic Devices XVII (M. Osinski, B. Witzigmann, F. Henneberger, Y. Arakawa, Eds.) 7211, 721114 (2009)

31. 22 Gb/s long wavelength VCSELs W. Hofmann, M. Müller, A. Nadtochiy, C. Meltzer, A. Mutig, G. Böhm, J. Rosskopf, D. Bimberg, M.-C. Amann, and C. Chang-Hasnain Optics Express 17, 17547 (2009)

32. 32 Gbit/s multimode fibre transmission using high-speed, low current density 850 nm VCSEL P. Westbergh, J.S. Gustavsson, A. Haglund, A. Larsson, F. Hopfer, G. Fiol, D. Bimberg, and A. Joel Electronics Letters 45, 366 (2009)

33. Electrically pumped, micro-cavity based single photon source driven at 1 GHz A. Lochmann, E. Stock, J.A. Töfflinger, W. Unrau, A. Toropov, A. Bakarov, V. Haisler, and D. Bimberg Electronics Letters 45, 566 (2009)

34. Frequency response of large aperture oxide-confined 850 nm vertical cavity surface emitting lasers A. Mutig, S.A. Blokhin, A.M. Nadtochiy, G. Fiol, J.A. Lott, V.A. Shchukin, N.N. Ledentsov, and D. Bimberg Appl. Phys. Lett. 95, 131101 (2009)

35. Modeling highly efficient RCLED-type quantum dot based single photon emitters M.C. Münnix, A. Lochmann, D. Bimberg, and V.A. Haisler IEEE Journal of Quantum Electronics 45, 1084 (2009)

36. Oxide-confined 850 nm VCSELs operating at bit rates up to 40 Gbit/s S.A. Blokhin, J.A. Lott, A. Mutig, G. Fiol, N.N. Ledentsov, M.V. Maximov, A.M. Nadtochiy, V.A. Shchukin, and D. Bimberg Electronics Letters 45, 501 (2009)

37. Polarization switching in quantum-dot vertical-cavity surface-emitting lasers L. Olejniczak, M. Sciamanna, H. Thienpont, K. Panajotov, A. Mutig, F. Hopfer, and D. Bimberg IEEE Photonics Technology Letters 21, 1008 (2009)

38. Temperature-dependent small-signal analysis of high-speed high-temperature stable 980 nm VCSELs A. Mutig, G. Fiol, K. Pötschke, P. Moser, D. Arsenijević, V.A. Shchukin, N.N. Ledentsov, S.S. Mikhrin, I.L. Krestnikov, D.A. Livshits, A.R. Kovsh, F. Hopfer, and D. Bimberg IEEE Journal of Selected Topics in Quantum Electronics 15, 679 (2009)

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39. 1.55 µm high-speed VCSELs enabling error-free fiber-transmission up to 25 Gbit/s M. Müller, W. Hofmann, A. Nadtochiy, A. Mutig, G. Bohm, M. Ortsiefer, D. Bimberg, and M.-C. Amann Proc. of Int. Semiconductor Laser Conference (ISLC 2010), Kyoto, Japan, September 2010 , 156 (2010)

40. 40 Gbit/s error-free operation of oxide-confined 850 nm VCSEL P. Westbergh, J.S. Gustavsson, B. Kögel, A. Haglund, A. Larsson, A. Mutig, A. Nadtochiy, D. Bimberg and A. Joel Electronics Letters 46, 1014 (2010)

41. 850 nm VCSEL operating error-free at 40 Gbit/s P. Westbergh, J.S. Gustavsson, B. Kögel, Å. Haglund, A. Larsson, A. Mutig, A. Nadtochiy, and D. Bimberg Proc. of Int. Semiconductor Laser Conference (ISLC 2010), Kyoto, Japan, September 2010 , 154 (2010)

42. A small form-factor and low-cost opto-electronic package for short-reach 40 Gbit/s serial speed optical data links J.- R. Kropp, J.A. Lott, N.N. Ledentsov, P. Otruba, K. Drögemüller, G. Fiol, D. Bimberg, I. Ndip, R. Erxleben, U. Maaß, M. Klein, G. Lang, H. Oppermann, H. Schröder and H. Reichl Electronic System-Integration Technology Conference (ESTC), (2010)

43. Characteristics of metal-cavity surface-emitting microlaser C.-Y. Lu, S.-W. Chang, and S. L. Chuang, T.D. Germann, U.W. Pohl, and D. Bimberg 2010 IEEE Photonics Society 23rd Annual Meeting IEEE Catalog: CFP10LEO (CDR), 240 (2010)

44. Comparison between two types of photonic-crystal cavities for single photon emitters W. Fan, Z. Hao, E. Stock, J. Kang, Y. Luo, and D. Bimberg Semiconductor Science Technology 26, 014014 (2010)

45. CW substrate-free metal-cavity surface microemitters at 300 K C.-Y. Lu, S.-W. Chang, S.L. Chuang, T.D Germann, U.W. Pohl and D. Bimberg Semiconductor Science Technology 26, 014012 (2010)

46. Evolution of high-speed long-wavelength vertical-cavity surface-emitting lasers W. Hofmann Semiconductor Science Technology 26, 014011 (2010)

47. Frequence response of oxide-confined 850 nm VCSELs S.A. Blokhin, A. Mutig, A.M. Nadtochiy, G. Fiol, J.A. Lott, V.A. Shchukin, N.N. Ledentsov, D. Bimberg Proc. of 18th Int. Symp. “Nanostructures: Physics and Technology”, St. Petersburg, Russia, June 2010 (Zh.I. Alferov, L. Esaki, Eds.), 35 (2010)

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48. Highly temperature-stable modulation characteristics multioxide-aperture high-speed 980 nm vertical cavity surface emitting lasers A. Mutig, J.A. Lott, S.A. Blokhin, P. Wolf, P. Moser, W.A.M. Nadtochiy, A. Payusov, and D. Bimberg Appl. Phys. Lett. 97, 151101 (2010)

49. High-speed 850 nm oxide confined VCSELs for DATACOM applications A. Mutig, S.S. Blokhin, A.A. Nadtochiy, G. Fiol, J.A. Lott, V.A. Shchukin, N.N. Ledenstov, D. Bimberg Proc. of SPIE: Vertical-Cavity Surface-Emitting Lasers XIV, edited by James K. Guenter, Kent D. Choquette 7615, 76150N (2010)

50. High-speed 850 nm VCSELs for 40 Gb/s transmission J. Gustavsson, P. Westbergh, K. Szczerba, Å. Haglund, A. Larsson, M. Karlsson, P. Andrekson, F. Hopfer, G. Fiol, D. Bimberg, B.-E. Olsson, A. Kristiansson, S. Healy, E. O'Reilly, A. Joel Proc. of SPIE: Semiconductor Lasers and Laser Dynamics IV (Krassimir Panajotov; Marc Sciamanna; Angel A. Valle; Rainer Michalzik, Eds.) 7720, 772002 (2010)

51. High-speed 980 nm VCSELs for very short reach optical interconnects A. Mutig, J. Lott, S. Blokhin, P. Moser, P. Wolf, W. Hofmann, A. Nadtochiy, A. Payusov, and D. Bimberg Proc. of Int. Semiconductor Laser Conference (ISLC 2010), Kyoto, Japan, September 2010 , 158 (2010)

52. High-speed single-photon source based on self-organized quantum dots E. Stock, W. Unrau, A. Lochmann, J. A. Töfflinger, M. Öztürk, A.I. Toropov, A.K. Bakarov, V.A. Haisler and D. Bimberg Semiconductor Science Technology 26, 014003 (2010)

53. Metal-cavity surface-emitting microlaser at room temperature C.-Y. Lu, S.-W. Chang, S. L. Chuang, T.D. Germann, and D. Bimberg Appl. Phys. Lett. 96, 251101 (2010)

54. Monolithic electro-optically modulated vertical cavity surface emitting laser with 10 Gb/s open-eye operation T. D. Germann A. Strittmatter A. Mutig A.M. Nadtochiy J.A. Lott S.A. Blokhin L.Ya. Karachinsky V.A. Shchukin N.N. Ledentsov U.W. Pohl and D. Bimberg Physica Status Solidi C 7 (10), 2552 (2010)

55. Optical components for very short reach applications at 40 Gb/s and beyond N.N. Ledentsov, J.A. Lott, V.A. Shchukin, A. Mutig, T.D. Germann, S.A. Blokhin, A.M. Nadtochiy, L.Y. Karachinsky, D. Bimberg Proc. of SPIE: Physics and Simulation of Optoelectronic Devices XVIII, edited by Bernd Witzigmann, Fritz Henneberger, Yasuhiko Arakawa, Marek Osinski 7597, 7597F (2010)

56. Oxide confined 850 nm VCSELs for high speed datacom applications P. Moser, A. Mutig, J.A. Lott, S.A. Blokhin, G. Fiol, A.M. Nadtochiy, N.N. Ledentsov and D. Bimberg Proc. of SPIE: Semiconductor Lasers and Laser Dynamics IV (Krassimir Panajotov; Marc Sciamanna; Angel A. Valle; Rainer Michalzik, Eds.) 7720, 77201W (2010)

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57. Polarization switching and polarization mode hopping in quantum dot vertical-cavity surface-emitting lasers L. Olejniczak, K. Panajotov, H. Thienpont, M. Sciamanna, A. Mutig, F. Hopfer, D. Bimberg Proc. of SPIE: Semiconductor Lasers and Laser Dynamics IV (Krassimir Panajotov; Marc Sciamanna; Angel A. Valle; Rainer Michalzik, Eds.) 7720, 77201G (2010)

58. Quantum dots for single and entangled photon emitters E. Stock, D. Bimberg, A. Lochmann, A. Schliwa, W. Unrau, M. Münnix, S. Rodt, A.I. Toropov, A. Bakarov, A.K. Kalagin, and V.A. Haisler Proc. of SPIE: Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling VII, Kurt G. Eyink, Frank Szmulowicz, Diana L. Huffaker (Eds.) 7610, 7610G (2010)

59. Substrate-free metal cavity surface-emitting laser with CW operation at room temperature C.-Y. Lu, S.-W. Chang, and S.L. Chuang, T.D. Germann and D. Bimberg Proc. of Int. Semiconductor Laser Conference (ISLC 2010), Kyoto, Japan, September 2010 , 15 (2010)

60. Ultrafast VCSELs for Datacom D. Bimberg IEEE Photonics Journal 2, 273 (2010)

c) Edge Emitters: High-Frequency Lasers and Amplifiers, High-Brightness Lasers

61. High-brightness and ultranarrow-beam 850 nm GaAs/AlGaAs photonic band crystal lasers and single-mode arrays T. Kettler, K. Posilovic, L.Ya. Karachinsky, P. Ressel, A. Ginolas, J. Fricke, U.W.Pohl, V.A. Shchukin, N.N. Ledentsov, D. Bimberg, J. Jönsson, M. Weyers, G. Erbert, and G. Tränkle IEEE Journal of Selected Topics in Quantum Electronics 15, 901 (2009)

62. High-speed small-signal cross-gain modulation in quantum-dot semiconductor optical amplifiers at 1.3 µm C. Meuer, J. Kim, M. Laemmlin, S. Liebich, G. Eisenstein, R. Bonk, T. Vallaitis, J. Leuthold, A. Kovsh, I. Krestnikov, and D. Bimberg IEEE Journal of Selected Topics in Quantum Electronics 15, 749 (2009)

63. Quantum dot semiconductor lasers of the 1.3 µm wavelength range with high temperature stability of the lasing wavelength (0.2 nm/K) L.Ya. Karachinsky, I.I. Novikov, Y.M. Shernyakov, N.Y. Gordeev, A.S. Payusov, M.V. Maximov, S.S. Mikhrin, M.B. Lifshits, V.A. Shchukin, P.S. Kop'ev, N.N. Ledentsov, and D. Bimberg Semiconductors 43, 680 (2009)

64. Quantum-dot semiconductor mode-locked lasers and amplifiers at 40 GHz G. Fiol, C. Meuer, H. Schmeckebier, D. Arsenijević, S. Liebich, M. Laemmlin, M. Kuntz, and D. Bimberg IEEE Journal of Quantum Electronics 45, 1429 (2009)

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65. Role of carrier reservoirs on the slow phase recovery of quantum dot semiconductor optical amplifiers J. Kim, C. Meuer, D. Bimberg, and G. Eisenstein Appl. Phys. Lett. 94, 41112 (2009)

66. Small-signal cross-gain modulation and crosstalk characteristics of quantum-dot semiconductor optical amplifiers at 1.3 µm J. Kim , M. Laemmlin, C. Meuer, S. Liebich, D. Bimberg, and G. Eisenstein Phys. Stat. Sol. (b) 246, 864 (2009)

67. Theoretical and experimental study of high-speed small-signal cross-gain modulation of quantum-dot semiconductor optical amplifiers J. Kim, M. Laemmlin, C. Meuer, D. Bimberg, G. Eisenstein IEEE Journal of Quantum Electronics 45, 240 (2009)

68. Ultrahigh speed nanophotonics D. Bimberg, G. Fiol, C. Meuer, D. Arsenijević, J. Kim, S. Liebich, M. Laemmlin, M. Kuntz, H. Schmeckebier, and G. Eisenstein Proc. of SPIE: Physics and Simulation of Optoelectronic Devices XVII (M. Osinski, B. Witzigmann, F. Henneberger, Y. Arakawa, Eds.) 7211, 721117 (2009)

69. 1.3 µm range 40 GHz quantum-dot mode-locked laser under external continuous wave light injection or optical feedback G. Fiol, M. Kleinert, D. Arsenijević and D. Bimberg Semiconductor Science Technology 26, 014006 (2010)

70. 10.7 W peak power picosecond pulses from high-brightness photonic band crystal laser diode S. Riecke, K. Posilovic, T. Kettler, D. Seidlitz, V.A. Shchukin, N.N. Ledentsov, K. Lauritsen and D. Bimberg Electronics Letters 46, 1393 (2010)

71. 40 GHz and 160 GHz mode-locked quantum-dot laser showing pulse width of 750 fs at 1.3 µm H. Schmeckebier, G. Fiol, C. Meuer, D. Arsenijević, D. Bimberg Proc. of SPIE: Semiconductor Lasers and Laser Dynamics IV (Krassimir Panajotov; Marc Sciamanna; Angel A. Valle; Rainer Michalzik, Eds.) 7720, 772010 (2010)

72. 80 Gb/s multi-wavelength booster amplification in an InGaAs/GaAs quantum-dot semiconductor optical amplifier C. Schmidt-Langhorst, C. Meuer, A. Galperin, H. Schmeckebier, R. Ludwig, D. Puris, D. Bimberg, K. Petermann, C. Schubert Proc. of ECOC 2010 - European Conference and Exhibition on Optical Communication IEEE Catalog Number: CFP10425-ART, Mo.1.F.6 (2010)

73. Complete pulse characterization of quantum-dot mode-locked lasers suitable for optical communication up to 160 Gbit/s H. Schmeckebier, G. Fiol, C. Meuer, D. Arsenijević, and D. Bimberg Optics Express 18, 3415 (2010)

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74. Cross-gain modulation and four-wave mixing for wavelength conversion in undoped and p-doped 1.3-µm quantum dot semiconductor optical amplifiers C. Meuer, H. Schmeckebier, G. Fiol, D. Arsenijević, J. Kim, G. Eisenstein, D. Bimberg IEEE Photonics Journal 2, 141 (2010)

75. Dynamical regimes in a monolithic passively mode-locked quantum dot laser A.G. Vladimirov, U. Bandelow, G. Fiol, D. Arsenijević, M. Kleinert, D. Bimberg, A. Pimenov, and D. Rachinskii Journal of the Optical Society of America B-Optical Physics 27, 2102 (2010)

76. Effect of inhomogeneous broadening on gain and phase recovery of quantum-dot semiconductor optical amplifiers J. Kim, C. Meuer, D. Bimberg, and G. Eisenstein IEEE Journal of Quantum Electronics 46, 1670 (2010)

77. Finite element simulation of the optical modes of semiconductor lasers J. Pomplun, S. Burger, F. Schmidt, A. Schliwa, D. Bimberg, A. Pietrzak, H. Wenzel, and G. Ebert Physica Status Solidi B 247, 846 (2010)

78. Four-wave mixing in 1.3 µm quantum-dot semiconductor optical amplifiers D. Bimberg, C. Meuer, G. Fiol, H. Schmeckebier and D. Arsenijević Proc. of ICTON 2010 IEEE Catalog Number: CFP10485-USB (CD-ROM), We.D4.21 (2010)

79. High-power high-brightness semiconductor lasers based on novel waveguide concepts D. Bimberg, K. Posilovic, V. Kalosha, T. Kettler, D. Seidlitz, V.A. Shchukin, N.N. Ledentsov, N.Y. Gordeev, L.Y. Karachinsky, I.I. Novikov, M.V. Maximov, Y.M. Shernyakov, A.V. Chunareva, F. Bugge, M. Weyers Proc. of SPIE: Novel In-Plane Semiconductor Lasers IX, edited by Alexey A. Belyanin, Peter M. Smowton 7616, 76161 (2010)

80. Hybrid mode-locking in a 40 GHz monolithic quantum dot laser G. Fiol, D. Arsenijević, D. Bimberg, A.G. Vladimirov, M. Wolfrum, E.A. Viktorov, and P. Mandel Appl. Phys. Lett. 96, 011104 (2010)

81. Influence of the pump wavelength on the gain and phase recovery of quantum-dot semiconductor optical amplifiers J. Kim, C. Meuer, D. Bimberg, and G. Eisenstein Semiconductor Science Technology 26, 014007 (2010)

82. Large-signal response of semiconductor quantum-dot lasers K. Ludge, R. Aust, G. Fiol, M. Stubenrauch, D. Arsenijević, D. Bimberg, and E. Schöll IEEE Journal of Quantum Electronics 46, 1755 (2010)

83. Linear and nonlinear semiconductor optical amplifiers J. Leuthold, R. Bonk, T. Vallaitis, A. Marculescu, W. Freude, C. Meuer, D. Bimberg, R. Brenot, F. Lelarge, G.-H. Duan Optical Fiber Communication Conference, OSA Technical Digest (CD) (2010)

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84. Linear and nonlinear semiconductor optical amplifiers W. Freude, R. Bonk, T. Vallaitis, A. Marculescu, A. Kapoor, E.K. Sharma, C. Meuer, D. Bimberg, R. Brenot, F. Lelarge, G.-H. Duan, C. Koos, J. Leuthold Proc. of ICTON 2010 IEEE Catalog Number: CFP10485-USB (CD-ROM), We.D4.11 (2010)

85. Locking characteristics of a 40GHz hybrid mode-locked monolithic quantum dot laser A.G. Vladimirov, M. Wolfrum, G. Fiol, D. Arsenijević, D. Bimberg, E. Viktorov, P. Mandel, D. Rachinskii Proc. of SPIE: Semiconductor Lasers and Laser Dynamics IV (Krassimir Panajotov; Marc Sciamanna; Angel A. Valle; Rainer Michalzik, Eds.) 7720, 77200Y (2010)

86. Looking on the bright side S. Riecke, K. Posilovic, T. Kettler, D. Seidlitz, V.A. Shchukin, N.N. Ledentsov, K. Lauritsen and D. Bimberg Electronics Letters 46, 1357 (2010)

87. Modeling of photonic crystal based high power high brightness semiconductor lasers V. Shchukin, N. Ledentsov, V. Kalosha, T. Kettler, K. Posilovic, D. Seidlitz , D. Bimberg, N.Yu. Gordeev, L.Ya. Karachinsky, I.I. Novikov, Y.M. Shernyakov, A.V. Chunareva, M.V. Maximov Proc. of SPIE: Physics and Simulation of Optoelectronic Devices XVIII, edited by Bernd Witzigmann, Fritz Henneberger, Yasuhiko Arakawa, Marek Osinski 7597, 75971A (2010)

88. Numerical simulation of temporal and spectral variation of gain and phase recovery in quantum-dot semiconductor optical amplifiers J. Kim, C. Meuer, D. Bimberg, and G. Eisenstein IEEE Journal of Quantum Electronics 46, 405 (2010)

89. Optical and electrical power dynamic range of semiconductor optical amplifiers in radio-over-fiber networks S. Koenig, J. Pfeifle, R. Bonk, T. Vallaitis, C. Meuer, D. Bimberg, C. Koos, W. Freude, J. Leuthold Proc. of ECOC 2010 - European Conference and Exhibition on Optical Communication IEEE Catalog Number: CFP10425-ART, Th.10.B.6 (2010)

90. Quantum dot semiconductor optical amplifiers at 1.3 µm for applications in all-optical communication networks H. Schmeckebier, C. Meuer, D. Bimberg, C. Schmidt-Langhorst, A. Galperin, and C. Schubert Semiconductor Science Technology 26, 014009 (2010)

91. Tilted waveguide and PBC lasers: Novel cavity designs for narrow far-fields and high brightness D. Bimberg, K. Posilovic, V. Kalosha, T. Kettler, D. Seidlitz, V.A. Shchukin, N.N. Ledentsov, S. Riecke, K. Lauritsen, F. Bugge and M. Weyers 2010 IEEE Photonics Society 23rd Annual Meeting IEEE Catalog: CFP10LEO (CDR), 475 (2010)

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d) Nanoflash Memories

92. A novel nonvolatile memory based on self-organized quantum dots A. Marent, M. Geller, D. Bimberg Microelectronics Journal 40, 492 (2009)

93. Hole-based memory operation in an InAs/GaAs quantum dot heterostructure A. Marent, T. Nowozin, J. Gelze, F. Luckert, and D. Bimberg Appl. Phys. Lett. 95, 242114 (2009)

94. Temperature and electric field dependence of the carrier emission processes in a quantum dot-based memory structure T. Nowozin, A. Marent, M. Geller, D. Bimberg, N. Akçay, and N. Öncan Appl. Phys. Lett. 94, 42108 (2009)

95. Nanomemories using self-organized quantum dots M. Geller, A. Marent, D. Bimberg Handbook of Nanophotonics. Nanoelectronics and Nanophotonics (K. Sattler, ed.), chapter 2 (2010)

96. The QD-Flash: A quantum dot-based memory device A. Marent, T. Nowozin, M. Geller and D. Bimberg Semiconductor Science and Technology 26, 14026 (2010)

e) Magnetic Resonance Investigations

97. Magnetic and structural properties of transition metal doped zinc-oxide nanostructures A.O. Ankiewicz, W. Gehlhoff, J.S. Martins, A.S. Pereira, S. Pereira, A. Hoffmann, E.M. Kaidashev, A. Rahm, M. Lorenz, M. Grundmann, M.C. Carmo, T. Trindade, N.A. Sobolev Phys. Stat. Sol. (b) 4, 766 (2009)

98. EPR identification of intrinsic and transition metal-related defects in ZnGeP2 and other II-IV-V2 compounds W. Gehlhoff, A. Hoffmann Physica B 404, 4942 (2009)

99. EDEPR of impurity centers embedded in silicon microcavities N.T. Bagraev, W. Gehlhoff, D.S. Gets, L.E. Klyachkin, A.A. Kudryavtsev, A.M. Malyarenko, V.A. Mashkov, V.V. Romanov Physica B 404, 5140 (2009)

100. A systematic study on zinc oxide materials containing group I metals (Li, Na,K) - Synthesis from organometallic precursors, characterization, and properties S. Polarz, A. Orlov, A. Hoffmann, M.R. Wagner, C. Rauch, R. Kirste, W. Gehlhoff, Y. Aksu, M. Driess, M.W.E. van den Berg, and M. Lehmann Chemistry of Materials 21, 3889 (2009)

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101. Lithium related deep and shallow acceptors in Li-doped ZnO nanocrystals C. Rauch, W. Gehlhoff, M. R. Wagner, E. Malguth, G. Callsen, R. Kirste, B. Salameh, A. Hoffmann, S. Polarz, Y. Aksu, and M. Driess Journal of Applied Physics 107, 24311 (2010)

102. EDESR and ODMR of impurity centers in nanostructures inserted in silicon microcavities N.T. Bagraev, V.A. Mashkov, E.Yu. Danilovsky, W. Gehlhoff, D.S. Gets, L.E. Klyachkin, A.A. Kudryavtsev, R.V. Kuzmin, A.M. Malyarenko und V.V. Romanov Applied Magnetic Resonance 39, 113 (2010)

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9.1.4 Invited Talks

D. Bimberg Ultrahigh speed nanophotonics

IEEE/LEOS Winter Topical Meeting Series on Nonlinear Dynamics in Photonics Systems, Innsbruck, Austria, January 2009

D. Bimberg Nano-VCSELs for the terabus 17th International Symposium Nanostructures: Physics and Technology, Minsk, Belarus, June 2009

D. Bimberg High speed single photon emitters for quantum communication, Rusnanotech 2009 - The Second Nanotechnology International Forum, Moscow, Russia, October 2009

D. Bimberg Quantum dots for single and entangled photon emitters

Conference 7610: Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling VII at SPIE Photonics West, San Francisco, California, USA, January 2010

D. Bimberg High-power high-brightness semiconductor lasers based on novel concepts

Conference 7616: Novel In-Plane Semiconductor Lasers IX at SPIE Photonics West, San Francisco, California, USA, January 2010

D. Bimberg Our daily life with semiconductor lasers DPG Frühjahrstagung der Sektion AMOP, Hannover, Germany, March 2010

D. Bimberg Semiconductor quantum dots: Same, same, but different International Symposium Semiconductor Heterostructures: Physics, Technology, Applications, St. Petersburg, Russia, March 2010

D. Bimberg Our daily life with semiconductor lasers DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM), Regensburg, Germany, March 2010

D. Bimberg Flying Q-bits and entangled photons enabling quantum cryptography 2010 Villa Conference on Interaction Among Nanostructures (VCIAN-2010) Santorini, Greece, June 2010

D. Bimberg Our daily life with semiconductor lasers International Nano-Optoelectronic Workshop, ( iNow 2010), Beijing and Changchun, China, August 2010

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D. Bimberg Nanophotonics for future Datacom and Ethernet networks International Workshop on High Speed Semiconductor Lasers (HSSL), Wroclaw, Poland, October 2010

D. Bimberg Tilted waveguide and PBC lasers: Novel cavity designs for narrow far-fields and high brightness IEEE Photonics Society 23rd Annual Meeting, Denver, USA, November 2010

S.L. Chuang Metal-cavity nanolasers 2010 Villa Conference on Interaction Among Nanostructures (VCIAN-2010) Santorini, Greece, June 2010

G. Fiol QD monolithic mode locked lasers Nonlinear Dynamics in Quantum Dot Devices (Minisymposium) Weierstrass Institute for Applied Analysis and Stochastics (WIAS), Berlin, Germany, November 2009

T. Germann MOVPE of a metal-cavity surface-emitting laser operating CW at room-temperature 15th International Conference on Metal Organic Vapor Phase Epitaxy, Lake Tahoe, USA, May 2010

W. Hofmann Long-wavelength vertical-cavity surface-emitting lasers with a high-contrast grating DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM), Regensburg, Germany, March 2010

V. Kalosha High-brightness edge-emitting semiconductor lasers based on concepts of photonic band crystal and titled wave lasers DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM), Regensburg, Germany, March 2010

A. Lochmann Cavity-enhanced emission in electrically driven quantum dot single-photon-emitters SPIE-Europe Microtechnologies for the New Millenium, (EMT-09), Dresden, Germany, May 2009

A. Marent Quantum dot flash memories: The best of two worlds DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM), Regensburg, Germany, March 2010

A. Marent Self-organized quantum dots for novel nano-memories International Conference on Superlattices, Nanostructures and Nanodevices (ICSNN-2010), Beijing, China, July 2010

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C. Meuer Influence of p-doping in quantum dot semiconductor optical amplifiers at 1.3 μm 11th International Conference on Transparent Optical Networks (ICTON 2009), S. Miguel, Azores, Portugal, June/July 2009

C. Meuer Four-wave mixing in 1.3 µm quantum-dot semiconductor optical amplifiers 12th International Conference on Transparent Optical Networks (ICTON 2010), München, Germany, June 2010

A. Mutig Nano-VCSELs for the Terabus 17th International Symposium "Nanostructure: Physics and Technology" St. Petersburg, Russia, June 2009

A. Mutig High-speed 850 nm oxide confined VCSELs for DATACOM applications

Conference 7615: Vertical-Cavity Surface-Emitting Lasers XIV at SPIE Photonics West, San Francisco, California, USA, January 2010

U. Pohl Metal-cavity surface-emitting microlaser Int. Conf. on the Physics of Semiconductors (ICPS 2010), Seoul, Korea, July 2010

A. Schliwa Single photon sources based on semiconductor quantum dots WTM 2010 IEEE Photonics Society Winter Topical on Semiconductor Nanolasers, Palma de Mallorca, Spain, January 2010

H. Schmeckebier 160 GHz sub-picosecond mode-locked quantum-dot laser pulses European Semiconductor Laser Workshop 2010, Pavia, Italy, September 2010

A. Strittmatter Green light-emitting diodes and laser heterostructures on semi-polar GaN(11-22)/sapphire substrates DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM), Regensburg, Germany, March 2010

E. Stock Self-organized quantum dots as single and entangled photon emitters DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM), Regensburg, Germany, March 2010

E. Stock Self-organized quantum dots for single photon emitters 18th International Symposium Nanostructures: Physics and Technology , St. Petersburg, Russia, June 2010

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9.1.5 Diploma Theses

Dejan Arsenijević Erzeugung ultrakurzer optischer Pulse mit Quantenpunktlasern

16.02.2009

Johannes Gelze Ladungsträgerdynamik in Quantenpunkt-basierten Speicherbausteinen 28.07.2009

Annika Högner Quantenpunktbasierte Speicherbausteine 21.12.2010

Gerald Hönig Mehrteilchen-Zustände in Nitrid-basierten Quantenpunkten 16.10.2009

Benjamin Mayer Automatisierte Erfassung der Fundamentaldaten von VCSEL-Wafern 22.10.2010

Gang Lou Epitaxie vergrabener GaAs-basierter Laserstrukturen 18.10.2009

Holger Schmeckebier Analyse von optischen Pulsen modengekoppelter Quantenpunkt-Halbleiterlaser 19.06.2009

Daniel Seidlitz Wellenlängenstabilisierte Halbleiterlaser auf Basis neuer Wellenleiterkonzepte 15.01.2010

Jan Amaru Töfflinger Quantenpunkte für Einzelphotonenemitter 18.03.2010

Peter Benedikt Weber High-speed vertical cavity emitting lasers 03.06.2009

Philip Wolf Prozessierung und Charakterisierung von oberflächen-emittierenden Lasern 08.07.2010

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9.2. Department II

Department IIa: Prof. Dr. rer. nat. Christian Thomsen

Department IIb: Prof. Dr. rer. nat. Janina Maultzsch

Department IIc: Prof. Dr. Axel Hoffmann Prof. em. Dr.-Ing. Dr. h.c. mult. Immanuel Broser

9.2.a Department IIa

Prof. Dr. rer. nat. Christian Thomsen

9.2a.1 Staff

Secretary

Mandy Neumann

Technical Staff

Sabine Morgner

Ing.grad. Heiner Perls

Michael Mayer

Senior Scientists

Dr. Dirk Heinrich

Dr. Holger Lange

Dr. Marcel Mohr

Dr. Niculina Peica

Dr. Harald Scheel

Dr. Andrei Schliwa

PhD Candidates (status of 31.12.2010: thesis completed = c)

Dipl.-Phys. Sevak Khachadorian

Dipl.-Phys. Marcel Mohr (c)

Dipl.-Phys. Matthias Müller (c)

Dipl.-Phys. Grit Petschick

Dipl.-Phys. Nils Rosenkranz

Dipl.-Phys. Andrei Schliwa (c)

Dipl.-Phys. Norman Tschirner

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Diploma and Teacher Students (status of 31.12.2010: thesis completed = c)

Jeffrey Bronsert

Juri Brunnmeier

Max Bügler (c)

Ralf Dornath

Sebastian Gade

Roland Gillen

Stefan Grützner

Frederike Kneer

Ronny Kirste (c)

Thomas Kure

Jakob Löber

Andreas Moschini

Felix Nippert

Christian Nitschke

Nadine Oswald

Thomas Plocke (c)

Nils Scheuschner

Maria-Astrid Schröter

Moritz Schubotz

Franz Schulze

Sebastian Siewert

Sergej Solopow

Matthias Sturm

Mehmet Can Ucar

Asmus Vierck

Mario Wegner

Marina Zajnulina

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9.2a.2 Summary of Activities

The activity of this group is centered on optical spectroscopy of carbon nanotubes, wide and narrow-gap semiconductors nanostructures, 2D electron gases, quantum dots, semiconductor core-shell nanodots and ferrofluids. Emphasis in the work on carbon nanotubes was put on the understanding of the electroni properties and how they compare to those of graphene and graphene nanoribbons. There is close collaboration with the group of Prof. Janina Maultzsch on these topics. As part of the investigations in the Cluster of Excellence “Catalysis” we expanded our investigations to functionalized carbon nanotubes. In the nanostructure-related project of the Sonderforschungsbereich 787 investigations focused on Raman and fir-spectroscopy of quantum dots and their luminescence properties as far as they are related to device applications. Our investigations of Si nanowires covered the difference on properties of nanowires compared to the bulk material. We investigated Si nanowires under large hydrostatic pressure. Our work on surfacted ferrofluids continues. In this period we covered mostly the behavior of ion-stabilized ferrofluids in an applied magnetic field. These fluids - aside from physics research - are of interest for medical applications.

We continued to expand our laboratory with remotely controlled experiments (remoteFarm) which are used in the education of – in particular – engineering students. These experiments are controlled over the internet and available on a 24/7 basis. Modern control and evaluation software allow experimenting from a remote location and contribute to the excellence in teaching at TU Berlin. Our remoteFarm is increasingly becoming used in international projects as best practice laboratory.

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9.2a.3 Publications

1. Theory of multiwall carbon nanotubes as waveguides and antennas in the infrared

and the visible regimes M. V. Shuba, G. Ya. Slepyan, S. A. Maksimenko, C. Thomsen, A. Lakhtakia Phys. Rev. B 79, 155403 (2009)

2. Geometry dependence of the phonon modes in CdSe nanorods Holger Lange, Mikhail Artemyev, Ulrike Woggon, Christian Thomsen Nanotechnology 20, 045705 (2009)

3. Carbon nanotube as a nanoscale Cherenkov-type light emitter – nanoFEL K. G. Batrakov, S.A. Maksimenko, P.P. Kuzhir, C. Thomsen Phys. Rev. B 79, 125408 (2009)

4. Phonons in bulk CdSe and CdSe nanowires M. Mohr and C. Thomsen Nanotechnology 20, 115707 (2009)

5. Geometry dependence of the phonon modes in CdSe nanorods Holger Lange, Mikhail Artemyev, Ulrike Woggon, Christian Thomsen Nanotechnology 20, 045705 (2009)

6. Longitudinal optical phonons in metallic and semiconducting carbon nanotubes M. Fouquet, H. Telg, J. Maultzsch, Y. Wu, B. Chandra, J. Hone, T. F. Heinz, and C. Thomsen Phys. Rev. Lett. 102, 075501 (2009)

7. Chemical vapor deposition of carbon layers on Si {001} substrates T.I. Milenov, P.M. Rafailov, G.V. Avdeev, C. Thomsen J. Optoelectronics and Advanced Materials 11, 1273-1276 (2009)

8. Spectroscopic studies on electrochemically doped and functionalized singel-walled carbon nanotubes P. M. Rafailov, T. I. Milenov, M. Monev, G. V. Avdeev, C. Thomsen, U. Dettlaff-Weglikowska, S. Roth J. Optoelectronics and Advanced Materials 11, 1339-1342 (2009)

9. Vibrational properties of graphene nanoribbons by first-principles calculations Roland Gillen, Marcel Mohr, Christian Thomsen, Janina Maultzsch Phys. Rev. B 80, 155418 (2009)

10. Lattice distortions in a crystal caused by doping with copper A.V. Egorysheva, T.I. Milenov, P.M. Rafailov, C. Thomsen, R. Petrova, V.M. Skorikov and M.M. Gospodinov Solid State Comm. 149, 1616-1618 (2009)

11. Resonance Raman study of the superoxide reductase from Archaeoglobus fulgidus, E12 mutants and a ’natural variant’ S. Todorovic, J.V. Rodrigues, A.F. Pinto, C. Thomsen, P. Hildebrandt, M. Teixeira, D.H. Murgida Phys. Chem. Chem. Phys. 11, 1809-1815 (2009).

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12. Victor-spaces: virtual and remote experiments in cooperative knowledge spaces S. Cikic, S. Jeschke, N. Ludwig, U. Sinha, C. Thomsen in: Grid enabled remote instrumentation; Series: Signals and Communication Technology 329-343 (2009)

13. Networking Resources for Research and Scientific Education in Nanoscience and Nanotechnologies S. Jeschke, N. Natho, O. Pfeiffer, C. Thomsen 2008 International Conference on Nanoscience and Nanotechnology (Australian Research Council, Melbourne, 2008), 234-237

14. Acetylene: a key growth precursor for single-walled carbon nanotube forests G. Zhong, S. Hofmann, F. Yan, H. Telg, J. Warner, D. Eder, C. Thomsen, W. Milne, J. Robertson J. Phys. Chem. B, 113, 17321 (2009)

15. Two-dimensional electronic and vibrational band structure of uniaxially strained graphene from ab initio calculations M. Mohr, K. Papagelis, J. Maultzsch, C. Thomsen Phys. Rev. B 80, 205410 (2009)

16. Kohn anomaly and electron-phonon interaction at the K-derived point of the Brillouin zone of metallic nanotubes P. Rafailov, J. Maultzsch, C. Thomsen, U. Dettlaff-Weglikowska, S. Roth Nano Lett. 9, 3343-3348 (2009)

17. Resonance Raman spectra of -carotene in solution and in photosystems revisited: an experimental and theoretical study Norman Tschirner, Matthias Schenderlein, Katharina Brose, Eberhard Schlodder, Maria Andrea Mroginski, Christian Thomsen and Peter Hildebrandt Phys. Chem. Chem. Phys. 11, 11471-11478 (2009)

18. Use of carbon nanotubes for VLSI interconnects J. Robertson, G. Zhong, S. Hofmann, B.C. Bayer, C.S. Esconjauregui, H. Telg and C. Thomsen Diamond and Related Materials 18, 957-962 (2009)

19. Thin-walled Er3+:Y2O3 nanotubes showing up-converted fluorescence Christoph Erk, Sofia Martin Caba, Holger Lange, Stefan Werner, Christian Thomsen, Martin Steinhart, Andreas Berger and Sabine Schlecht Phys. Chem. Chem. Phys. 11, 3623-3627 (2009)

20. Polariton effects in the dielectric function of ZnO excitons obtained by ellipsometry M. Cobet, C. Cobet, M.R. Wagner, N. Esser, C. Thomsen, and A. Hoffmann Appl. Phys. Lett. 96, 031904 (2010)

21. Electronic properties of propylamine-functionalized single-walled carbon nanotubes M. Müller, R. Meinke, J. Maultzsch, Z. Syrgiannis, F. Hauke, A. Pekker, K. Kamaras, A. Hirsch, C. Thomsen ChemPhysChem 11, 2444 (2010)

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22. Terahertz conductivity peak of composite materials containing single-wall carbon nanotubes: theory and interpretation of experiment G. Slepyan, M. Shuba, S. Maksimenko, C. Thomsen, A. Lakhtakia Phys. Rev. B 81, 205423 (2010)

23. Symmetry based analysis of the Kohn anomaly and electron-phonon interaction in graphene and carbon nanotubes I. Milocevic, N. Kepcija, E. Dobardzic, M. Mohr, J. Maultzsch, C. Thomsen, M. Damnjanovic Phys. Rev. B 81, 233410 (2010)

24. Electron-phonon coupling in grapheme I. Milocevic, N. Kepcija, E. Dobardzic, M. Damnjanovic M. Mohr, J. Maultzsch, C. Thomsen Int. J. of Modern Physics B, 24, 655-660 (2010)

25. Observation of excitonic effects in metallic single-walled carbon nanotubes P. May, H. Telg, G. Zhong, J. Robertson, C. Thomsen, and J. Maultzsch Phys. Rev. B 82, 195412 (2010).

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9.2a.4 Invited Talks

R. Gillen Ab initio calculations of the phonon spectra of graphene nanoribbons Frühjahrstagung der Deutschen Physikalischen Gesellschaft, Dresden, Germany, March 2009

R. Gillen Vibrational properties of graphene NanoLabFor-Project Meeting, Faculty of Physics, University of Belgrade, Serbia, June 2009

S. Khachadorian Deployment of Remote Experiments: OnPReX Course at TU Berlin IEEE-EDUCON Engineering Education Conference, Madrid, Spain, April 2010

P. Kusch Temperature dependent Raman scattering experiments of CdSe nanorods Frühjahrstagung der Deutschen Physikalischen Gesellschaft, Dresden, Germany, March 2009

R. Meinke Resonant Raman scattering on chemically functionalized carbon nanotubes Frühjahrstagung der Deutschen Physikalischen Gesellschaft, Dresden, Germany, March 2009

M. Mohr Exploring the two-dimensional Brillouin zone of the electronic and the vibrational band structure of uniaxially strained graphene NanoLabFor-Project Meeting, Faculty of Physics, University of Belgrade, Serbia, June 2009

M. Mohr Electronic and vibrational properties of graphene under strain International Winterschool on Electronic Properties of Novel Materials (IWEPNM), Kirchberg, Austria, March 2010

N. Rosenkranz Molecular Dynamics Simulations of interactin carbon pico- and nanotubes NanoLabFor-Project Meeting, Faculty of Physics, University of Belgrade, Serbia, June 2009

H. Telg Characterization of isolated metallic and semiconducting nanotubes by Raman spectroscopy International Winterschool on Electronic Properties of Novel Materials (IWEPNM), Kirchberg, Austria, March 2009

H. Telg Characterization of isolated metallic and semiconducting nanotubes by Raman spectroscopy European Materials Research Society, 2009 Spring Meeting, Strasbourg, France, June 2009

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H. Telg Resonant Raman spectroscopy on carbon nanotubes Electronic and Optical Properties of Molecular Nanostructures, KIT, Karlsruhe, Germany, June 2009

H. Telg In situ characterization of carbon nanotubes Technotubes Project Meeting, Paris, France, September 2009

C. Thomsen Vibrational modes in graphene and semiconductor nanorods Wonton 2009 Matsushima, Japan, June 2009

C. Thomsen Phonons in graphene and carbon nanotubes ICREA Workshop on Phonon Engineering 2010, Barcelona, Spain, May 2010

C. Thomsen Vibrational properties of graphene and graphene nanoribbons Symposium “Optical and Vibrational Spectroscopies”, Queretaro, Mexico, August 2010

M. Wagner Magneto-optic and recombination dynamic of complex bound excitons in homoepitaxially grown ZnO epilayers Photonics West 2009, San Jose, USA, January 2009

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9.2a.5 Diploma Theses

Fabian Gericke Optische Untersuchungen an phasenveränderbaren Materialien

wie Ge2Sb2Te5 und deren Schaltverhalten 27.06.2010

Roland Gillen Schwingungseigenschaften von Graphen Nanoribbons anhand

von ab initio Berechnungen 12.04.2009

Philipp Hummel IR spectroscopic studies of hydrogenanes

06.01.2010 Patryk Kusch Temperaturabhängigkeit der Scheingungseigenschaften vonCdSe

Nanorods 14.05.2010

Reinhard Meinke Optische Übergänge in Amin-funktionalisierten Kohlenstoff-

Nanoröhren 24.07.2010

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9.2.b Department IIb

Prof. Dr. rer. nat. Janina Maultzsch

9.2b.1 Staff

Secretary

Mandy Neumann

Technical Staff

Sabine Morgner

Ing.grad. Heiner Perls

Michael Mayer


Dipl.-Phys. Katharina Brose

Dipl.-Phys. Jan Laudenbach

Dipl.-Phys. Patrick May

Diploma and Teacher Students (status of 31.12.2010: thesis completed = c)

Nils Scheuschner

Felix Herziger

9.2b.2 Summary of Activities

Our research activities focus on the physical properties of nanostructures, in particular carbon nanotubes, graphene and nanoribbons, Si clusters, as well as biomolecules such as carotene and photosystemII. We study their optical, vibrational and electronic properties and the interaction between their electronic and vibrational system.

Our research on carbon nanotubes focused on exciton-phonon coupling and on chemically functionalized nanotubes. The exciton-phonon coupling strength was investigated by resonant Raman scattering. We found a distinct dependence of the coupling strength on the chiral angle of nanotubes (see figure), which is important to know when studying the abundance of specific (n,m) nanotubes in enriched samples. Furthermore, we presented experimental evidence for ~50 meV exciton binding energy in metallic carbon nanotubes. In our nanotube activities we collaborate closely with AG Thomsen.

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From: H. Telg, C. Thomsen, and J. Maultzsch, Journal of Nanophotonics 4, 041660 (2010). For graphene nanoribbons we studied symmetry and vibrational properties by ab-initio calculations. We determined the symmetry properties of armchair and zigzag nanoribbons and identified the Raman active modes, in particular the width-dependent breathing-like mode (see figure). Our predictions have been recently confirmed on well-defined, chemically synthesized nanoribbons.

From: R. Gillen, M. Mohr, and J. Maultzsch, Phys. Rev. B 81, 205426 (2010).

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9.2b.3 Publications

1. Longitudinal optical phonons in metallic and semiconducting carbon nanotubes

M. Fouquet, H. Telg, J. Maultzsch, Y. Wu, B. Chandra, J. Hone, T. F. Heinz, and C. Thomsen Phys. Rev. Lett., 102, 075501 (2009)

2. Vibrational properties of graphene nanoribbons by first-principles calculations Roland Gillen, Marcel Mohr, Christian Thomsen, Janina Maultzsch Phys. Rev. B, 80, 155418 (2009)

3. Two-dimensional electronic and vibrational band structure of uniaxially strained graphene from ab initio calculations M. Mohr, K. Papagelis, J. Maultzsch, C. Thomsen Phys. Rev. B, 80, 205410 (2009)

4. Kohn anomaly and electron-phonon interaction at the K-derived point of the Brillouin zone of metallic nanotubes P. Rafailov, J. Maultzsch, C. Thomsen, U. Dettlaff-Weglikowska, S. Roth Nano Lett., 9, 3343-3348 (2009)

5. Electronic properties of propylamine-functionalized single-walled carbon nanotubes M. Müller, R. Meinke, J. Maultzsch, Z. Syrgiannis, F. Hauke, A. Pekker, K. Kamaras, A. Hirsch, C. Thomsen submitted to ChemPhysChem (01/10)

6. Symmetry based analysis of the Kohn anomaly and electron-phonon interaction in graphene and carbon nanotubes I. Milocevic, N. Kepcija, E. Dobardzic, M. Mohr, J. Maultzsch, C. Thomsen, M. Damnjanovic Phys. Rev. B, in print (2010)

7. Electron-phonon coupling in grapheme I. Milocevic, N. Kepcija, E. Dobardzic, M. Damnjanovic M. Mohr, J. Maultzsch, C. Thomsen Int. J. of Modern Physics B, 24, 655-660 (2010)

8. Excitonic Rayleigh scattering spectra of metallic single-walled carbon nanotubes Ermin Malic, Janina Maultzsch, Stephanie Reich, and Andreas Knorr Phys. Rev. B 82, 115439 (2010).

9. Observation of excitonic effects in metallic single-walled carbon nanotubes P. May, H. Telg, G. Zhong, J. Robertson, C. Thomsen, and J. Maultzsch Phys. Rev. B 82, 195412 (2010).

10. Raman intensities of the radial-breathing mode in carbon nanotubes: the exciton-phonon coupling as a function of (n1, n2) H. Telg, C. Thomsen, and J. Maultzsch Journal of Nanophotonics 4, 041660 (2010)

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11. Observation of Breathing-like Modes in an Individual Multiwalled Carbon Nanotube C. Spudat, M. Müller, L. Houben, J. Maultzsch, K. Goss, C. Thomsen, C. M. Schneider, and C. Meyer Nano Lett. 10, 4470 (2010)

12. Excitonic absorption spectra of metallic single-walled carbon nanotubes Ermin Malic, Janina Maultzsch, Stephanie Reich, and Andreas Knorr Phys. Rev. B 82, 035433 (2010)

13. Symmetry properties of vibrational modes in graphene nanoribbons R. Gillen, M. Mohr, and J. Maultzsch Phys. Rev. B 81, 205426 (2010)

14. Time-resolved Raman spectroscopy of optical phonons in graphite: Phonon anharmonic coupling and anomalous stiffening H. Yan, D. Song, K.F. Mak, I. Chatzakis, J. Maultzsch, and T. F. Heinz Phys. Rev. B 80, 121403(R) (2009)

9.2b.4 Invited Talks

J. Maultzsch Vibrational properties of carbon nanotubes and graphene nanoribbons ACS (American Chemical Society) Meeting, Washington, DC, August 16-20, 2009

J. Maultzsch Vibrational properties of graphene nanoribbons IWEPNM 2010, Kirchberg, Austria, March 6-13, 2010

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9.2.c Department IIc

Prof. Dr. Axel Hoffmann

Prof. em. Dr.-Ing. Dr. h.c. mult. Immanuel Broser

9.2c.1 Staff

Secretary

Ines Rudolph

Senior Scientists

Dr. Sebaz Reparaz

Dr. Markus Wagner


Dipl.-Phys. Miran Alic

Dipl.-Phys. Max Bügler

Dipl.-Phys. Gordon Callsen

Dipl.-Phys. Munise Cobet (10.07.2010)

Dipl.-Phys. Ute Haboeck

Dipl.-Phys. Ronny Kirste

Dipl.-Phys. Martin Kaiser

Dipl.-Phys. Christian Kindel

Dipl.-Phys. Gordon Callsen

Dipl.-Phys. Christian Nennstiel

Dipl.-Phys. Stefan Werner

Dipl.-Phys. Patrick Zimmer

Diploma Students (status of 31.12.2010: thesis completed = c)

Miran Alic (c)

Dorian Alden

Max Bügler (c)

Gordon Callsen

Ole Hitzemann (c)

Martin Kaiser ( c )

Thomas Kure

Thomas Switaiski

Stefan Mohn

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Christian Nennstiel (c)

Christian Rauch (c)

Thomas Switaiski (c)

Jan-Henrik Schulze (c)

9.2c.2 Summary of Activities

The main research activities focus on the optical, vibronical and structural properties of II-VI and III-V semiconductors with special emphasis on ZnO-, AlN-, InN- and GaN-based structures. The investigations are carried out on single crystals, epitaxially grown homo- and heterostructures, and especially low-dimensional structures like quantum wells, nanowires, and quantum dots. Excitonic complexes as a representative of the optical properties play an outstanding role in the analysis of semiconductors. Excitonic excitation and relaxation mechanisms and the dynamics of these processes are in the center of our interest which facilitates deep insight into the physics of nitride- and oxide-based bulk and nanostructured material. Knowledge of the energetic structure and relaxation mechanisms of free and bound excitons allows precise analysis of defects created during e.g. growth, annealing, and doping procedures. Especially, the analysis of extended structural defect centers in ZnO yielded novel insight based on studies conducted in our research group. Fundamental distinctions in the optical signature of extended structural defect centers allow their separation from common e.g. dopant-related point defects. All investigations are carried out in close cooperation with research groups aiming for the development and optimization of e.g. new optoelectronic devices like blue light-emitting diodes and lasers based on wide bandgap II-VI and III-V semiconductors. Cooperations have been established with many research groups in Germany, Switzerland, Spain, France, Russia, Belarus, Australia, China, UK, USA and Japan. The essential physical topics include:

exciton polaritons and bound excitons in bulk crystals and excitonic complexes in low dimensional structures based on GaN, InN, AlN, InGaN, AlGaN, InGaAs and ZnO,

shallow and deep centers,

recombination dynamics and non-radiative processes,

non-linear optical effects of pure and doped wide bandgap semiconductors,

coherent dynamics,

analysis of doping and dopant compensation mechanisms,

functionalization of nanostructures,

cavity-like properties of nanowires, and

determination of deformation potentials.

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The problem of p-dopant compensation and passivation in GaN-, AlGaN- and ZnO-based structures attracts a lot of current attention. Intensive studies were dedicated to the behavior of donor-acceptor pair emissions of highly p-doped ZnO- and GaN-layers. Furthermore, the study of coherent processes especially with highly spatially localized excitation is a further issue in our research. Coherent lifetimes react very sensitively to defect structures and can thus help to optimize growth, annealing and doping techniques. Four-wave mixing techniques could be applied to epitaxial layers of different II-VI compounds to receive non-linear quantum beats. We have shown that they originate either from zero-field split excited states of one complex or from interference between two different bound excitons. The finalized construction of two either IR or UV optimized µTRPL setups facilitates analysis and imaging of nanostructures with only diffraction limited spatial resolution. As a result we were able to clearly resolve and analyze the spatial distribution of excitonic lifetimes in e.g. cavity-like single ZnO nanowires which resulted several remarkable publications. Additionally, the effect of functionalization of nanostructures with organic molecules was studied with main focus on the occurring drastic excitonic lifetime changes. Further future effords will be dedicated to the highly promising field of nanostructure functionalization because of the outstandingly promising future applications in gas sensors, catalytic processes and optoelectronics. However, the µTRPL technique does not only allow such characterization of one-dimensional structures, even quasi zero-dimenstional structures like individual quantum dots can be analyzed. The purpose of the Sfb 787 project headed by Axel Hoffmann and Christian Thomsen is to study the influence of the electron-phonon interaction in low-dimensional semiconductor systems. Here, our main focus is the investigation of the dynamical properties of excitonic states in II-VI and III-V quantum dots based on the µTRPL technique. The collaboration with Yasuhiko Arakawa from the University of Tokyo resulted in a still ongoing research exchange which originated several publications dealing with the characterization of single GaN quantum dots. The large internal fields of such quantum dots make them an outstanding candidate for future optoelectronic applications with main focus on secure and efficient high speed data transmission. In contrast to such directly application oriented characterization of e.g. quantum dots we also participate in the determination of very fundamental material parameters like deformation potentials. Especially the phonon deformation potentials in nitrides and ZnO have caught our recent interest due to their lack or partly inconsistency in the literature. Raman measurements under the application of hydrostatic as also uniaxial stress allowed us to clarify and publish in the literature still missing and by the scientific community higly appreciated values. Only the close international collaboration with Zlatko Sitar from the North Carolina State University and Alejandro Goñi from the ICMAB realized the access to state of the art material and for the high pressure measurements required equipment.

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9.2c.3 Publications

1. Bound and free excitons in ZnO: optical selection rules in the absence and

presence of time reversal symmetry M.R. Wagner, H.W. Kunert, A.G.J. Machatine, A. Hoffmann, P. Niyongabo, J.

Malherbe, J. Barnas Microelectronics Journal Volume 40, 289 (2009)

2. Influence of substrate surface polarity on homoepitaxial growth of ZnO layers by chemical vapour deposition

M. R. Wagner, T.P. Bartel, R. Kirste, A. Hoffmann, J. Sann, S. Lautenschläger, B. K. Meyer, C. Kieselowski Phys. Rev. B 79 (2009), 035307

3. A systematic study on ZnO Materials containing group I materials (Li,Na,K)-

synthesis from precursors, characterization, and properties S. Polarz, A. Orlov, A. Hoffmann, M.R. Wagner, C. Rauch, R. Kirste, W. Gelhoff, Y.

Aksu, M. Driess, M. W. van den Berg,M. Lehmann Chem. Mat. 21 (2009), 3889 4. Wave propagation of Rabi oscillations in one-dimensional quantum dot chain G. Ya Slepyan, Y.D. Yerchak, S.A. Maksimenko, A. Hoffmann

Phys. Lett. A 373 (2009), 1374

5. Matter coupling to strong electromagnetic fields in two-level quantum systems with broken inversion symmetry

O.V. Kibis, G. Ya Slepyan, S.A. Maksimenko, A. Hoffmann Phys. Rev. Lett. 102 (2009), 023601

6. Magnetic and structural properties of transition metal doped zinc-oxide nanostructures A.O. Ankiewicz, W. Gehlhoff, J.S. Martins, A. S. Pereira, S. Pereira, A. Hoffmann, E. M. Kaidashev, A. Rahm, M. Lorenz, M. Grundmann, M. C. Carmo, T. Trindade, N. A. Sobolev phys. stat. sol. (b) 246 (2009), 776

7. Nitrogen incorporation in homoepitaxial ZnO CVD epilayers S. Lautenschlaeger, S. Eisermann, B.K. Meyer, G. Callsen, M.R. Wagner, A. Hoffmann phys. stat. sol. RRL, 3 (2009), 16-18

8. Strong coupling of light with one-dimensional quantum dot chain from Rabi oscillations to Rabi waves

G. Ya Slepyan, Y.D. Yerchak, S.A. Maksimenko, A. Hoffmann Physics, Chemistry and Aplication of Nanostructures 3 (2009), 12071

9. 7 valence band symmetry related hole fine splitting of boundexcitons in ZnO

observed in magneto-optical studies Markus R. Wagner, Jan- Hindrik Schulze, Ronny Kirste, Munise Cobet, Axel Hoffmann, Christian Rauch, Anna V. Rodina, B.K. Meyer, Uwe Röder, Klaus Thonke Phys. Rev. B 80 (2009), 205203

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10. Phonons and electronic states of ZnO, Al2O3 and Ge in the presence of time reversal symmetry

A. G.J. Mechatine, H.W. Kunert, A. Hoffmann, J. Malherbe, J. Barnas, R. Seguin, M.R. Wagner, P. Niyongabo, N. Nephale

Journal of Physics Conference Series 92 (2009), 12071 11. EPR identification of intrinsic and transition metal-related defects in ZnGeP2 and

other II-IV-V2 compounds W. Gehlhoff, A. Hoffmann Physica B 404 (2009), 4942 12. Light-matter coupling in nanostructures without an inversion center O.V. Kibis, G. Ya Slepyan, S. A. Maksimenko, A. Hoffmann Superlattice and Microstructures 47 (2010), 216 13. Polariton effects in the dielectric function of ZnO excitons obtained by

ellipsometry M. Cobet, C. Cobet, M.R. Wagner, N. Esser, C. Thomsen, A. Hoffmann Applied Physics Letters 96 (2010), 031904

14. Optical spectra of ZnO in the far UV: First Principle Calculations and

Ellipsometric measurements Paola Gori, Munise Rakel, Christoph Cobet, Wolfgang Richter, Norbert Esser, Axel Hoffmann, Rodolfo Del Sole, Antonio Cricenti, Olivia Pulci Phys. Rev. B 81 (2010), 125207

15. Size-dependent recombination dynamics in ZnO nanowires

J. S. Reparaz, F. Güell, M. R. Wagner, A. Hoffmann, A. Cornet, J. R. Morante, Appl. Phys. Lett. 96 (2010), 053105

16. Lithium related deep and shallow acceptors in Li- doped ZnO nanocrystals C. Rauch, W. Gelhoff, M.R. Wagner, E. Malguth, G. Callsen, R. Kirste, B. Salameh,

A. Hoffmann, S. Polarz, Y. Aksu, M. Driess J. Appl. Phys. 107 (2010), 024311

17. Identification of a donor related recombination channel in ZnO thin films Matthias Brandt, Holger von Wenckstern, Gabriele Benndorf, Martin Lange, Christof P. Dietrich, Christian Kranert, Chris Sturm, Rüdiger Schmidt-Grund, Holger Hochmuth, Michael Lorenz, Marius Grundmann, Markus R. Wagner, Miran Alic, Christian Nenstiel, and Axel Hoffmann Phys. Rev. B 81 (2010), 073306

18. Theory of time-resolved Raman scattering and fluorescence emission from

semiconductor quantum dots Julia Kabuß, Stefan Werner, Axel Hoffmann, Peter Hildebrandt, Andreas Knorr, Marten Richter Phys. Rev. B 81 (2010), 075314

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19. Growth temperature - phase stability relation in In1-xGaxN epilayers grown by high-pressure CVD G. Durkaya, M. Alevli, M. Buegler, R. Atalay, S. Gamage, M. Kaiser, R. Kirste, A. Hoffmann, M. Jamil, I. Ferguson and N. Dietz Mater. Res. Soc. Symp. Proc. Vol. 1202 © 2010 Materials Research Society 1202-I5.21-1

20. Clebsch-Gordan coefficients for scattering tensors in ZnO H. W. Kunert, M. R. Wagner, A. G. J. Machatine, P. Niyoganbo, J. Malherbe, A. Hoffmann, J. Barnas, W. Florek phys. stat. sol. (b) 247 (2010), 1802

21. Strong electron-photon coupling in one-dimensional quantum dot chain:

Rabi waves and Rabi wavepackets G. Ya. Slepyan, Y. D. Yerchak, A. Hoffmann, and F. G. Bass Phys. Rev. B 81 (2010), 085115

22. E-MRS 2009 Spring Meeting, Symposium J: Groupe III Nitride Semiconductors, Strassburg, France, Proceedings, Guest editors: Olivier Briot, Axel Hoffmann, Yasushi Nanishi, Fernando A. Ponce phys. stat. sol (c) 7, (2010), Wiley-VCH

23. Zinc Oxide- From fundamental properties towards novel application:

Influence of external fields Markus R. Wagner and Axel Hoffmann Chapter 8: Springer series in materials sciences 120 (2010), p 201 ed. Claus Franz Klingshirn, Bruno K. Meyer, Andreas Waag, Axel Hoffmann, Jean Geurts

24. Zinc Oxide- From fundamental properties towards novel application: Deep centres in ZnO Axel Hofmann, Enno Malguth and B.K. Meyer Chapter 10: Springer series in materials sciences 120 (2010), p 233 ed. Claus Franz Klingshirn, Bruno K. Meyer, Andreas Waag, Axel Hoffmann, Jean Geurts

25. Recombination dynamics in ZnO nanowires: surface states vs. mode quality factor J. S. Reparaz, F. Güell, M. R. Wagner, G. Callsen, R. Kirste, C. Claramunt, J. R. Morante, and A. Hoffmann Appl. Phys. Lett. 97 (2010), 133116

26. Spectral identification of impurities and native defects in ZnO

B.K. Meyer, D.M. Meyer, J. Stehr, A. Hoffmann Wiley-VCH Buch über ZnO ed. C. Litton (2010)

27. Reduction of the transverse effective charge of optical phonons in ZnO under

pressure J.S. Reparaz, L. R. Muniz, M. R. Wagner, A. R. Goni, M. I. Alonso, A. Hoffmann, B.K. Meyer App. Phys. Lett. 96 (2010), 231906

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28. Exciton fine-structure splitting in GaN/AlN quantum dots C. Kindel, S. Kako, T. Kawano, H. Oiishi, Y. Arakawa, G. Hönig, M. Winkelnkemper, A. Schliwa, A. Hoffmann, D. Bimberg Physical Review B 81 (2010), 241309 (R)

29. Molecular precursor route to a metastable from of zinc oxide Carlos Lizandara Pueyo, Stephan Siroky, Steve Landsmann, Maurits W. E. van den Berg, Markus R. Wagner, Juan S. Reparaz, Axel Hoffmann, Sebastian Polarz Chem. Mater. 22 (2010), 4263

30. Optical properties of InN grown on templates with controlled surface polarities Ronny Kirste, Markus R. Wagner, Jan H. Schulze, Andre Strittmatter, Ramon Colazzo, Zlatko Sitar, Mustafa Alevli, Nikolaus Dietz, Axel Hoffmann phys.stat sol. (a) 207 (2010), 2351

31. Large internal dipole moment in InGaN/GaN quantum dots Irina A. Ostapenko, Gerald Hönig, Christian Kindel, Sven Rodt, Andre Strittmatter, Axel Hoffmann, Dieter Bimberg Appl. Phys. Lett. 97 (2010), 063103

32. The influence of group V/III molar precursor ratio on the structural properties of InGaN layers grown by HPCVD G. Durkaya, M. Buegler, R. Atalay, I. Senevirathna, M. Alevli, O. Hitzemann, M. Kaiser, R. Kirste, A. Hoffmann, N. Dietz phys. stat. sol. (a) 207 (2010), 1379

33. Reactor pressure: growth temperature relation for InN epilayers grown by high-pressure CVD M. Buegler, S. Gamage, R. Atalay, J. Wang, I. Senevirathna, R. Kirste, T. Xu, M. Jamil, I. Ferguson, J. Tweedie, R. Collazo, A. Hoffmann, Z. Sitar, N. Dietz Proc. SPIE 7784 (2010), 77840F

34. Excited state properties of donor bound excitons in ZnO

Bruno. K. Meyer, Joachim Sann, Sebastian Eisermann, Stefan Lautenschlaeger, Markus R. Wagner, Martin Kaiser, Gordon Callsen, Juan S. Reparaz A. Hoffmann Phys. Rev. B 82 (2010), 115207

35. Shape anisotropy influencing functional properties: trigonal prismatic ZnO

nanoparticals as an example Carlos Lizandara Pueyo, Stephan Siroky, Markus R. Wagner, Axel Hoffmann, Juan S. Reparaz, Michael Lehmann, Sebastian Polarz Advance Functional Materials 21 (2011), 295

36. Raman and photoluminescence spectroscopic detection of surface-bound Li+O2-

defect sites in Li-doped ZnO nanocrystals derived from molecular precursors Ronny Kirste, Yilmaz Aksu, Markus R. Wagner, Sevak Khachadorian, Surajit Jana, Matthias Driess, Christian Thomsen, Axel Hoffmann Chem. Phys. Chem. 12 (2011), 1189

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37. Determination of phonon deformation potentials in wurtzite GaN and ZnO by uniaxial pressure dependent Raman measurements G. Callsen, J. S. Reparaz, M. R. Wagner, R. Kirste, C. Nenstiel, A. Hoffmann, and M. R. Phillips Appl. Phys. Lett. 98 (2011), 061906

38. Acoustic and optical phonon scattering in a single In(Ga)As quantum dot Erik Stock, Matthias-Rene Dachner, Till Warming, Andrei Schliwa, Anatol Lochmann,

Axel Hoffmann, Aleksandr I. Toropov, Askhat K. Kakarov, Ilya A. Derebzov, Marten Richter, Vladimir A. Haisler, Andreas Knorr, Dieter Bimberg, Phys. Rev. B 83 (2011), 041304(R)

39. Comment on the paper pss (a) 205, 1872: Paramagnetic and ferromagnetic

resonance studies on dilute magnetic semiconductors on GaN W. Gehlhoff, B. Salameh, A. Hoffmann phys. stat. sol. (a) 207 (2011), 1379

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9.2c.4 Invited Talks

Axel Hoffmann Spatially and time resolved spectroscopy of excitons and

phonons in low dimensional semiconductors School of Nanostructures, Santiago de Cuba, January 2009 Axel Hoffmann Optical and vibrational properties of high quality ZnO

substrates under uniaxial pressure SPIE Photonic West 2009, San Jose, USA, January 2009

Axel Hoffmann Single dot spectroscopy- nitrides vs. arsenides PLMNC 9 Lecce, Italy, April 2009 Axel Hoffmann Optical and vibrational properties of high quality ZnO

substrates MRS Fall Meeting 2010, Boston, USA, December 2009 Axel Hoffmann Radiative and nonradative decay in group III nitrides SPIE 2010, San Francisco, USA, January 2010 Axel Hoffmann Radiative and nonradative decay in group III nitrides Sinople 2010, Berlin, Germany, March 2010 Axel Hoffmann InAs- and GaN- quantum dots: Similarities and differences CIMTEC 2010, Montecantini Terme, Italy, June 2010 Axel Hoffmann Towards real-world quantum communication: Quantum

dots as non-classical light sources ISGN3, Montpellier, France, July 2010 Axel Hoffmann Optical and vibrational properties of high quality ZnO

substrates Int. Workshop of ZnO 2010, Changchun, China, August 2010

Axel Hoffmann Quantum dots as non-classical light sources: The interplay between polarization effects and electron-hole exchange INOW 2010, Changchun, China, August 2010

Axel Hoffmann Case study of successful Australian–European collaborations

BMBF workshop, Bonn, Germany, November 2010

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9.2b.5 Diploma Theses

Miran Alic Zeitaufgelöste Untersuchungen an niederdimensionalen III-V

Halbleitern 21.12.2009

Gordon Callsen Optische Eigenschaften von niederdimensionaln Halbleiterstrukturen 23.06.2009

Ole Hitzemann Untersuchungen an verdünnten magnetischen Halbleitern als Materialien für die Spintronik 25.05.2010

Martin Kaiser Optische Eigenschaften tiefer Zentren in Breitbandhalbleitern 26.02.2010

Christian Nenstiel Lumineszenz und Hochanregungsmechanismen in Gruppe-III Nitriden 20.07.2009

Jan-Hindrik Schulze Dynamische Eigenschaften von Breitband-Halbleitern in äußeren Feldern 29.05.2009

Thomas Switaiski Mikrophotolumineszenzuntersuchungen an Quantenpunkten 06.07.2009

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9.3 Department III

Prof. Dr. rer. nat. Mario Dähne

Prof. em. Dr.-Ing. Hans-Eckhart Gumlich

9.3.1 Staff

Secretary

Angela Berner (part time)

Technical Staff

Gerhard Pruskil

Senior Scientists

Dr. Holger Eisele

Dr. Lena Ivanova (until 06.06.2010)

Dr. Andrea Lenz

Dr. Rainer Timm (until 31.01.2009)

PhD Candidates (status of 31.12.2010 - thesis completed = c)

Dipl.-Phys. Martin Franz

Dipl.-Phys. Jan Grabowski (c)

Dipl.-Phys. Kai Hodeck (c)

Dipl.-Phys. Lena Ivanova (c)

Dipl.-Phys. Christopher Prohl

Diploma and Master Students (status of 31.12.2010 – thesis completed = c)

Stephan Appelfeller

Martin Franz (c)

Florian Genz (c)

Britta Höpfner (c)

Nadine Oswald (c)

Christopher Prohl (c)

Matthias Vetterlein (c)

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The main research subject of the group of Mario Dähne is the investigation of the structural and (local) electronical properties of semiconductor surfaces, interfaces, and nanostructures. In the experiments, special emphasis lies on the use of local probes, such as scanning-tunneling microscopy (STM) and spectroscopy (STS) and – for studies of buried structures – cross-sectional scanning-tunneling microscopy (XSTM) and spectroscopy (XSTS). Complementary information on the electronic band structure is obtained from angle-resolved photoelectron spectroscopy (ARPES) with synchrotron radiation at the Berlin storage ring BESSY. All experiments are performed in ultra-high vacuum (UHV). There are three experimental setups: 1. An STM chamber with a preparation chamber containing LEED, sputter gun and effusion

cells 2. A chamber designed especially for XSTM experiments 3. A III-V MBE chamber with in-situ STM analysis, provided by Prof. Jacobi from the Fritz-

Haber-Institut For ARPES experiments, chambers provided by cooperation partners are used. The most important recent results are given in the following: 1. Silicide thin films, nanowires, and clusters Using STM and ARPES, the formation and properties of lanthanide silicide nanostructures on Si surfaces were investigated in detail [3,6,16]. Both two-dimensional and one-dimensional electronic properties could be found for silicide nanowires. Using a display-type toroidal electron spectrometer developed by LaTrobe University in Bundoora, Australia, we were able to map the two-dimensional energy surfaces. Here a very similar two-dimensional dispersion was found both for silicide thin films on Si(111) and for nanowires on Si(557) [6,14], which could be related to hexagonal disilicide monolayers. The figure shows the structure of the nanowires on Si(557) and their Fermi surface. Currently, the formation, structure, and electronic properties of silicide clusters grown on Si surfaces are studied.

2. Initial stages of InAs quantum-dot growth In the MBE-STM chamber, the atomic structure of the evolving InAs wetting layer on the GaAs(001)-c(4×4) surface was studied up to quantum-dot formation [8,11,15]. The wetting layer was found to develop in a three-stage process, starting with In agglomerations, which transform at about 0.67 ML into a (4×3) reconstructed In2/3Ga1/3As monolayer, as shown in

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the figure. Further on, the In2/3Ga1/3As monolayer is covered by a (2×4) reconstructed InAs film. After 1.42 ML InAs exposure, the critical thickness for quantum-dot formation is reached.

3. Atomic structure of InAs/GaAs submonolayer nanostructures Using XSTM the atomic structure of submonolayer InAs nanostructures embedded in GaAs was studied [18]. The samples were grown in Department I using MOCVD. Rather small structures with very high densities in the 1012/cm2 range were observed. A strong vertical segregation with segregation lengths around 1 nm was found. The figure shows the XSTM image of a stack with 5 layers each containing 0.5 ML InAs separated by 16 layers of GaAs together with the variation of the local lattice constant and therewith of the local stoichiometry, allowing a quantitative analysis of the segregation. In the case of thin GaAs spacer layers, this leads to vertically coherent InGaAs structures instead of the nominally assumed InAs/GaAs stacks.

4. Formation of InAs quantum dashes in InGaAsP In a cooperation with the Heinrich-Hertz-Institut, using XSTM we studied InAs embedded within InGaAsP layers lattice matched on InP bulk material. Here we observed zero-dimen-sional nanostructures strongly elongated along [110] direction, so-called quantum dashes [7,13]. This observation is in contrast to the InAs/GaAs system, where smaller quantum dots are formed, exhibiting a rather 4-fold structural symmetry. The figure shows cross-sectional images of the InAs/InGaAsP/InP(001) quantum dashes taken at both perpendicular cleavage planes. The quantum dashes, marked by ellipses, have an almost binary InAs composition and

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a truncated pyramidal shape. Their lengths and widths were found to lie around 60 nm and 15 nm, respectively, resulting in lateral aspect ratios around 4. The quaternary matrix material surrounding the dashes is characterized by a lateral decomposition resulting in InAs-rich and GaP-rich columns, which are correlated with the positions of the quantum dashes, as marked by the dashed lines.

5. Influence of nitrogen on the properties of arsenide nanostructures In cooperation with the Paul-Drude-Institut and the Tyndall Institute in Cork, Ireland, the so-called diluted nitrides were studied [12,17]. Using XSTM it was found that nitrogen exposure during InAs quantum-dot growth leads to a strong dilution by Ga from the capping layer of otherwise compact InAs quantum dots. The figure shows InAs quantum dots grown without (left) and with (right) nitrogen exposure. It is observed that the indium even segregates into the substrate upon nitrogen exposure. Furthermore, the density of states of diluted GaAsN was measured using XSTS. Here the influence of nitrogen on the GaAs conduction band states could be studied in detail. It could be shown that the second band gap predicted by the so-called BAC model does not exist, but there is an energy interval of reduced DOS, which could be modelled well by an advanced theoretical approach contributed by the group from the Tyndall Institute in Cork.

6. Electronic structure of GaSb quantum rings embedded in GaAs The structural and local electronic properties of GaSb nanostructures on GaAs(001) were studied in a cooperation with the University of Cambridge, UK, and the Carnegie Mellon University in Pittsburgh, USA [5,19]. As shown in the XSTM image in the figure, here mostly GaSb ring structures are observed, which are filled by almost pure GaAs, in contrast to the more compact InAs/GaAs quantum dots. The GaSb quantum rings revealed a type-II band

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offset typical for the GaSb/GaAs system, as shown in the XSTS spectra in the figure. Furthermore, the contrast in XSTM images at type-II systems was studied in detail involving the effects of tip-induced band bending.

7. Structure and electronic properties of non-polar GaN surfaces Using XSTM and XSTS, we studied the atomic structure and electronic properties of the non-polar GaN(1010) cleavage surface [1,4,9,14] in cooperation with the Forschungszentrum Jülich and with Osram Opto-Semiconductors GmbH. We were able to achieve atomic resolution on the GaN(1010) surface and found that the surface is unreconstructed. As shown on the left side of the figure there are no intrinsic surface states within the fundamental band gap. Furthermore we found different dislocation types and could derive their burgers vectors, line directions, and charge states. An example for an uncharged perfect screw dislocation is shown on the right side of the figure. In addition, we could observe a modulation of the Si doping concentration during growth along the [0001] direction.

8. Electronic Structure of the InN(1120) surface Using XSTS we studied the (1120) surface of monocrystalline InN [Appl. Phys. Lett. 98, 062103 (2011)], in collaboration with both the Forschungszentrum Jülich and the National Tsing Hua University, Taiwan. We could derive a band gap of 0.7 eV for InN using only direct electronic measurements. Moreover, it could be shown that the assumed generality of an electron accumulation on InN surfaces is absent in the case of stoichiometric non-polar surfaces. In this case, the Fermi level is found within the fundmental band gap, indicating that the electron accumulation is not an intrinsic property of InN, but can be assigned to decomposition and/or adsorbance of molecules from the air. Furthermore, it could be shown that the fundamental bulk band gap is free of intrinsic surface states at the (1120) surface.

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9.3.3 Publications

1. Electronic properties of dislocations in GaN investigated by scanning tunneling microscopy, Ph. Ebert, L. Ivanova, S. Borisova, H. Eisele, A. Laubsch, and M. Dähne, Appl. Phys. Lett. 94, 062104 (2009).

2. Limits of In(Ga)As/GaAs quantum dot growth, A. Lenz, H. Eisele, R. Timm, L. Ivanova, R.L. Sellin, H.-Y. Liu, M. Hopkinson, U.W. Pohl, D. Bimberg, and M. Dähne, Phys. Stat. Sol. (b) 246, 717 (2009).

3. Structural and electronic properties of rare-earth silicide nanowires on Si(557), M. Wanke, K. Löser, G. Pruskil, and M. Dähne, Phys. Rev. B 79, 155428 (2009).

4. Doping modulation in GaN imaged by cross-sectional scanning tunneling microscopy, H. Eisele, L. Ivanova, S. Borisova, M. Dähne, M. Winkelnkemper, and Ph. Ebert, Appl. Phys. Lett. 94, 162110 (2009).

5. Contrast mechanisms in cross-sectional scanning tunneling microscopy of GaSb/GaAs type-II nanostructures, R. Timm, R.M. Feenstra, H. Eisele, A. Lenz, L. Ivanova, E. Lenz, and M. Dähne, J. Appl. Phys. 105, 093718 (2009).

6. Energy surfaces of rare-earth silicide films on Si(111), M. Wanke, M. Franz, M. Vetterlein, G. Pruskil, B. Höpfner, C. Prohl, I. Engelhardt, P. Stojanov, E. Huwald, J. Riley, and M. Dähne, Surf. Sci. 603, 2808 (2009).

7. Formation of InAs/InGaAsP quantum dashes on InP(001), A. Lenz, F. Genz, H. Eisele, L. Ivanova, R. Timm, D. Franke, H. Künzel, U.W. Pohl, and M. Dähne, Appl. Phys. Lett. 95, 203105 (2009).

8. Evolution of the InAs wetting layer on GaAs(001)c(4x4) on the atomic scale, J. Grabowski, C. Prohl, B. Höpfner, M. Dähne, and H. Eisele, Appl. Phys. Lett. 95, 233118 (2009).

9. Scanning tunneling microscopy on unpinned GaN(1100) surfaces: Invisibility of valence-band states, Ph. Ebert, L. Ivanova, and H. Eisele, Phys. Rev. B 80, 085316 (2009).

10. Adsorbate-induced restructuring of Pb mesas grown on vicinal Si(111) in the quantum regime, A.A. Khajetoorians, W. Zhu, J. Kim, S. Qin, H. Eisele, Z. Zhang, and C.-K. Shih, Phys. Rev. B 80, 245426 (2009).

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11. Atomic structure of the (4x3) reconstructed InGaAs monolayer on GaAs(001), H. Eisele, B. Höpfner, C. Prohl, J. Grabowski, and M. Dähne, Surf. Sci. 604, 283 (2010).

12. Effect of nitrogen on the InAs/GaAs quantum dot formation, L. Ivanova, H. Eisele, A. Lenz, R. Timm, O. Schumann, L. Geelhaar, H. Riechert, and M. Dähne, Phys. Stat. Sol. (c) 7, 355 (2010).

13. InAs nanostructures on InGaAsP/InP(001): Interaction of InAs quantum dash formation with InGaAsP decomposition, F. Genz, A. Lenz, H. Eisele, L. Ivanova, R. Timm, U.W. Pohl, M. Dähne, D. Franke, and H. Künzel, J. Vac. Sci. Technol. B 28, C5E1 (2010).

14. Cross-sectional scanning tunneling microscopy and spectroscopy of non-polar GaN(1100) surfaces, H. Eisele, S. Borisova, L. Ivanova, M. Dähne, and Ph. Ebert, J. Vac. Sci. Technol. B 28, C5G11 (2010).

15. Atomic structure and strain of the InAs wetting layer growing on GaAs(001), C. Prohl, B. Höpfner, J. Grabowski, M. Dähne, and H. Eisele, J. Vac. Sci. Technol. B 28, C5E13 (2010).

16. Electronic properties of dysprosium silicide nanowires on Si(557), M. Wanke, M. Franz, M. Vetterlein, G. Pruskil, C. Prohl, B. Höpfner, P. Stojanov, E. Huwald, J. Riley, and M. Dähne, J. Appl. Phys. 108, 064304 (2010).

17. Direct measurement and analysis of the conduction band density of states in diluted GaAs1-xNx alloys, L. Ivanova, H. Eisele, M.P. Vaughan, Ph. Ebert, A. Lenz, R. Timm, O. Schumann, L. Geelhaar, M. Dähne, S. Fahy, H. Riechert, and E.P. O’Reilly, Phys. Rev. B 82, 161201(R) (2010).

18. Atomic structure of buried InAs sub-monolayer depositions in GaAs, A. Lenz, H. Eisele, J. Becker, L. Ivanova, E. Lenz, F. Luckert, K. Pötschke, A. Strittmatter, U.W. Pohl, D. Bimberg, and M. Dähne, Appl. Phys. Express 3, 105602 (2010).

19. Confined states of individual type-II GaSb/GaAs quantum rings studied by cross-sectional scanning tunneling spectroscopy, R. Timm, H. Eisele, A. Lenz, L. Ivanova, V. Vossebürger, T. Warming, D. Bimberg, I. Farrer, D.A. Ritchie, and M. Dähne, Nano Lett. 10, 3972 (2010).

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9.3.4 Invited Talks

M. Dähne Rare earth silicide nanowires on silicon surfaces DPG Frühjahrstagung, Regensburg, 21.-26. March 2010

H. Eisele Scanning Tunneling Microscopy for Semiconductor Analysis, Solid state physics colloquium, Tyndall National Institute, Cork, Ireland, February 2009

H. Eisele The 2D-3D and Quantum Dot-Quantum Ring Phase Transitions during Growth of InAs/GaAs and GaSb/GaAs Nanostructures International Conference on the Formation of Semiconductor Interfaces, Weimar, July 2009

H. Eisele Material deposition and reorganization during growth and capping of GaAs-based nanostructures SemicoNano 2009, Anan, Japan, August 2009

H. Eisele Cross-sectional scanning tunnelling microscopy of non-polar GaN surfaces Abschlusskolloquium, DFG-Schwerpunkt Nitride, Universität Bremen, October 2009

H. Eisele XSTM and XSTS for the analysis of semiconductor nanostructures Festkörperkolloquium, Universität Marburg, December 2009

H. Eisele Cross-sectional scanning tunneling microscopy study of non-polar GaN(1100) surfaces International Workshop on Nitride Semiconductors, Tampa/FL, 19. – 23. Sep. 2010

H. Eisele Cross-sectional scanning tunneling microscopy of pure and diluted nitride semiconductors 18th International Vacuum Congress, Beijing, 23. – 27. Aug. 2010.

H. Eisele Semiconductor nano-structure analysis with scanning tunneling microscopy Paul-Drude-Institute, Berlin, 21. Jun. 2010

H. Eisele Nanostructure analysis using STM Blockseminar 2010 of the Graduiertenkolleg of the Sfb 787, TU Berlin, Graal-Müritz, 9. – 11. May 2010.

H. Eisele Cross-sectional STM and plane-view STM for the characterization of III-V semiconductor nanostructures University of California at Los Angeles, Los Angeles/CA, 1. Feb. 2010.

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H. Eisele Nature of surface states and dislocations on non-polar GaN(1100) surfaces investigated by scanning tunneling microscopy Palo Alto Research Center, Palo Alto/CA, 28. Jan. 2010

H. Eisele Cross-sectional scanning tunneling microscopy of non-polar GaN surfaces Department of Physics, Carnegie-Mellon-University, Pittsburgh/PA, 19. Jan. 2010

H. Eisele Cross-sectional scanning tunneling microscopy of non-polar GaN surfaces Center of High Technology Materials, University of New Mexico, Albuquerque/NM, 15. Jan. 2010.

H.-E. Gumlich Moderne Physiker: Ihre Haltung zum Glauben an Gott, Lehrerfortbildung für Ethik-Lehrer, Martin-Luther-Universität Halle-Wittenberg, June 2009

L. Ivanova Characterization of GaAsN Quantum Wells, GaInNAs by Scanning Tunneling Microscopy Solid state physics colloquium, Ohio University, Athens, USA, November 2009

L. Ivanova Structural and Electronic Properties of non-polar GaN(1-100) Surfaces Solid State physics colloquium, University of Michigan, Ann Arbor, USA, November 2009

L. Ivanova GaAsN/GaAs Semiconductors Studied by Scanning Tunneling Microscopy Festkörperkolloquium, Universität Marburg, December 2009

A. Lenz Structural investigation on III-V semiconductor heterostructures and magic clusters on Si(111)(7x7) Solid state physics colloquium, LaTrobe University, Bundoora, Australia, August 2009

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9.3.5 Diploma Theses

Martin Franz Atomare Struktur von Silizid-Nanodrähten

30.01.2009

Florian Genz Atomare Struktur von phoshpidbasierten Halbleiternanostrukturen 21.07.2009

Britta Höpfner Strukturelle Eigenschaften des InAs/GaAs-Systems vor und nach

der Quantenpunktentstehung 08.03.2009

Nadine Oswald Atomare Struktur von stickstoffhaltigen III-V-Halbleiternano-strukturen 07.12.2009

Christopher Prohl Strukturelle Eigenschaften von Submonolagen-Bedeckungen im

InAs/GaAs-Quantenpunktsystem 06.03.2009

Matthias Vetterlein Überwachsen von Silizid-Nanodrähten mit Silizium

09.03.2009

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9.4 Department IV

Prof. Dr. rer. nat. Michael Kneissl

Prof. Dr. rer. nat. Wolfgang Richter (retired)

9.4.1 Staff

Secretary

Claudia Hinrichs

Technical Staff

Matthias Dreier

Engelbert Eder

Senior Scientists

Dr. Markus Pristovsek

Dr. Patrick Vogt

Dr. Tim Wernicke

Dr. Abdul Kadir

PhD Candidates (status of 31.12.2010 – thesis completed = c)

Dipl.-Phys. Konrad Bellmann

Dipl.-Phys. Thomas Bruhn

Dipl.-Phys. Ralph Debusmann

Dipl.-Phys. Duc Dinh

Dipl.-Phys. Marcel Ewald

Dipl.-Phys. Martin Frentrup

Dipl.-Phys. Christian Friedrich

Dipl.-Phys. Tim Kolbe

Dipl.-Phys. Raimund Kremzow (c), until 30.11.2010

Dipl.-Phys. Martin Leyer

M. Sc. Neysha Lobo

Dipl.-Phys. Martin Martens

Dipl.-Phys. Christian Meißner

Dipl.-Phys. Simon Ploch

Dipl.-Phys. Jens Raß

Dipl.-Phys. Luca Redaelli

Dipl.-Phys. Jessica Schlegel

Dipl.-Phys. Daria Skuridina

Dipl.-Phys. Joachim Stellmach

Dipl.-Phys. Jan-Robert Van Look

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Diploma, Master and Bachelor Students (status of 31.12.2010 – thesis completed = c)

Eric Bauch (c)

Amelie Biermann (c)

Fabian Budack

Florian Duge

Johannes Falkenburg

Martin Frentrup (c)

Martin Guttmann, B.Sc. (c.)

Marc Hoffmann (c)

Michael Högele (c)

Michael Hoppe (c)

André Kruse (c)

Gunnar Kusch

Igor Kuznecov (c)

Martin Martens (c)

Frank Mehnke

Christoph Reich

Linda Riele (c)

Marc-Antonius Rothe

Özgür Savas (c)

Julia Schmermbeck, M.Sc.

Matthias Schmies (c)

Tilman Schwaner

Katrin Sedlmeier (c)

Toni Sembdner (c)

Sergej Solopow

Marcus Stascheit

Christian Ulbrich, B.Sc. (c)

Alexander Wolf, B.Sc. (c)

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The “Experimental Nanophysics and Photonics” group is exploring a wide range of topics including metalorganic vapor phase epitaxy (MOVPE) of group III-nitride compounds and nanostructures, the study of optical and electronic properties of semiconductor surfaces and interfaces, and the development of novel optoelectronic devices. The material system AlN-GaN-InN covers an extraordinarily wide wavelength range, that includes the entire visible spectrum and ranges from the deep ultraviolet (UV) to the near infrared. This exceptional versatility makes InAlGaN heterostructures exceedingly interesting for numerous new device applications. These include near and deep ultraviolet (UV) InAlGaN light emitting diodes (LEDs), high power and high brilliance blue-green laser diodes, GaN-based semiconductor disk lasers (SCDL), vertical cavity surface emitting lasers (VCSELs) and single photon emitter (SPE). These new devices are key enabler for numerous applications, including e.g. the purification of drinking water, phototherapy, medical diagnostics, laser projection displays, and quantum cryptography. The research activities in the “Experimental Nanophysics and Photonics” group are conducted in close collaboration with the GaN Optoelectronics Business Area at the Ferdinand-Braun-Institut, Leibniz Institut für Höchstfrequenztechnik (FBH) located on the Science and Technology Campus in Berlin-Adlershof. By combining competencies in both basic and applied research, our goal is to establish a European centre of excellence in the field of nitride materials growth and devices.

The research activities are being supported by a number of research grants. This includes the project “Materials for high brilliance green laser diodes” which is funded by the German Research Foundation (DFG) as part of the Collaborative Research Centre (SFB 787) “Semiconductor Nanophotonics”. In addition, the development of InGaN quantum well laser heterostructures on semipolar growth surfaces is supported within the DFG research group “Polarisation field control in nitride light emitters” (FOR 957). We have also obtained a number of individual grants from the German Research Foundation (DFG). These include the development of GaN-based semiconductor disk lasers (SCDL) for emission in the blue-violet wavelength range, the investigation of nanostructure growth during metalorganic vapour phase epitaxy by in-situ scanning tunnelling microscopy, and the investigation of atomic structure of InGaN surfaces. Funded by the German Federal Ministry of Education and Research (BMBF) the joint research project „Deep UV LEDs“ was established, which targets the development of highly efficient light emitting diodes in the UVB and UVC spectral range. In July 2009 a new BMBF funded regional growth core “Berlin WideBaSe” was launched. The research activities within Berlin WideBaSe are focused on the development, manufacturing and distribution of wide bandgap semiconductor optoelectronic and electronic devices. Berlin WideBaSe combines the know-how and technical resources of ten small and medium size companies as well as three research institutes in Berlin. In the context of the European Union the “RAINBOW” Initial Training Network (ITN) has been established with the goal to develop high quality InN layers and heterostructures for applications in solar cells and high frequency electronics. In addition the new EU STREP project “FemtoBlue” has been launched in September 2009 to develop short-pulse multi-section blue laser diodes.

The activities of the Experimental Nanophysics and Photonics Group are organized in three closely coupled research areas with complementary objectives:

- metalorganic vapour phase epitaxy of nitride based nano- and heterostructures

- the development of novel nanophotonic devices

- the characterization of surfaces and interfaces

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Epitaxy of nitride based materials and nanostructures

A major step in advancing our growth capability was the establishment of a new 3x2” Thomas Swan Close-Coupled Showerhead MOVPE reactor for the growth of III-nitride heterostructures, which complements our existing single wafer Epigress and Aixtron MOVPE systems. One of our goals in the area of epitaxy is to obtain a better understanding of the fundamental growth processes in MOVPE by using in-situ characterization techniques like spectroscopic ellipsometry, reflectometry and wafer curvature measurements. A fundamental challenge for the growth of nitride semiconductor alloys InGaN and AlGaN is the large strain at heterointerfaces due to the lattice mismatch. Apart from the limits imposed by strain, e.g. the formation of misfit dislocation or 3D growth, strain also effects the efficiency of light emitting devices, e.g. due to the quantum-confined Stark effect (QCSE). To accommodate strain in AlGaN layers grown on AlN/sapphire templates for LEDs emitting in the UV region, we have successfully developed short period superlattice structures. The superlattice structure enables crack-free growth in the entire composition range, giving a largely relaxed AlGaN template for devices. Such AlGaN templates also exhibit significantly reduced threading dislocation densities in comparison to AlN templates and offer the possibility for strain engineering. In the InGaN system we determined the critical thickness for relaxation and 2D to 3D transition on GaN templates and the effects on surface structure, alloy composition and defect density. The strain can be used by the formation of Quantum dots due to the strain induced Stranski-Krastanov growth mode. Furthermore such quantum dots can be used for single photon emitter as well as for lasers. We demonstrated control of quantum dot size and density over 2 orders of magnitude. Another novel approach is the growth of AlGaN and InGaN in so called semi- or nonpolar crystal orientations. These orientations are tilted with respect to the [0001] direction. Therefore, quantum wells on such crystal planes exhibit reduced polarization fields. First suitable substrates and growth parameters of the binary alloys InN, GaN and AlN needed to be established. Additionally, the use of foreign substrates can lead to the formation of domains with different crystal orientation. We demonstrated the growth of single phase semipolar InN, GaN and AlN as well as AlGaN in the whole composition range. Furthermore basic properties that define the growth are studied. They are very different to the (0001) surface. Desorption and adatom mobilities are anisotropic and depend strongly on the surface orientation.

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Pulsed electroluminescense of a threefold InGaN/GaN quantum well just below 3D transition (23% 2.5 nm).

2µm x 2µm Atomic Force Microscopy of low density InGaN quantum dots with an indium content of about 23 %.

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Nitride bases devices: From UV LEDs to blue-green lasers

The research profile of the group includes a strong emphasis on nanophotonic devices based on III-nitride wide bandgap semiconductors. The activities include the development technology base for the growth and fabrication of light emitting diodes (LEDs) and laser diodes (LDs) as well as developing concepts for next generation short wavelength light sources. A new field of devices, solarblind UV photodetectors, is also currently studied utilizing epitaxy, device fabrication, characterization and simulation. The growth and fabrication processes of LED devices were successfully established as demonstrated by LEDs in the emitting in the green spectral range near 500 nm down to deep UVB LEDs emitting at 320 nm and first devices emitting below 300 nm. More complex and challenging growth and fabrication processes for LDs were also successfully established as demonstrated by 405 nm current-injection ridge-waveguide LDs under cw operation, current-injection LDs under pulsed operation from 400 nm to 435 nm as well as optically pumped laser structures from 326 nm to 470 nm. This technology base and the establishment of into state-of-the art devices build the foundation for the development of novel concepts for LEDs and LDs.

Photographic images of semipolar (20-21) InGaN MQW LED chips

emitting at 430 nm (left) and 500 nm (right).

The novel concepts that are under investigation aim for the extension of the wavelength range of LEDs and LDs as well as improving the efficiency and open up new applications. New applications are targeted by the development of multi-section laser diodes for ps-pulse generation. Also the development of semiconductor disk lasers opens up new applications due to the high pulse peak power and the high beam quality as well as the scalability and the possibility to include nonlinear optical element into the cavity. Semiconductor disk lasers with peak pulse output power of more than 300 W and an emission wavelength of 393 nm have been demonstrated. Meanwhile first semiconductor disk lasers with an emission wavelength of 420 nm have also been realized. In order to push the lasing wavelength towards the green spectral region, the growth of quantum dot active regions is studied. Also the blue-green wavelength region is targeted by lasers on non- and semipolar growth facets. Such structures suffer less from the quantum-confined Stark effect enabling higher material gain. Hereby the studies also revealed different incorporation efficiencies of indium into the active region allowing for more favourable growth conditions of long wavelength active regions. On the short wavelength side deep UV LEDs in the UV-B and UV-C range are studied. Epitaxy of such devices requires low defect density templates as described in the previous section and the ability to control n- and p-doping in AlGaN with high Al-content. 320 nm UV LEDs with milli-Watt emission power and 298 nm LEDs have been demonstrated. For the fabrication process the biggest issues are light extraction and heat dissipation. To solve these issues heterostructure design, simulation and growth as well as chip design and device fabrication

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interact strongly. The resulting concepts of flip-chip UV-LEDs with interdigitated finger-contacts, micropixel contacts or nanopixel contacts have proven to increase output power in a broad spectral range from 380 – 320 nm.

(a) (b)

(a) Photographic image of a 380 nm flip-chip UV-LED with micropixel contacts. (b) Emission spectra of InGaN RPG disk laser below and above the threshold. The inset shows the far-field intensity distribution.

The beam divergence is approximately 20 mrad.

Surface Science Research

Self-assembled ultra-thin molecular layers on solid substrates have emerged to an important material system for novel applications like biosensors or lab-on-the-chip concepts. For such applications a profound understanding of the interfacial structure and formation between the two material systems is required. We investigate the interface reactions between organic molecules and semiconductor surfaces including the technologically important III-nitrides. In particular we aim for an understanding of the general factors that determine the molecule-semiconductor interaction on an atomic scale. In the past two years we were able to demonstrate that the adsorption of molecules can cause a complex modification of the surface electronic properties of semiconductor materials, depending on the exact structural aspects of the respective interface formation. We have developed and established optical techniques for the non-destructive in-situ monitoring of molecular film growth in a sub-monolayer range. We could show that molecular orbitals of ordered organic films can be observed as optical anisotropies with RAS measurements. We have successfully demonstrated that a new UV-RAS setup (operating up to 9.5 eV) allows a direct observation of molecular orbitals of small molecules. By the help of the UV-RAS we could realize the controlled preparation of organic sub-monolayers on GaAs(001) surfaces. At these ultra-thin layers we could correlate the RAS signatures with transitions between electronic states of the molecules as determined by single molecule spectroscopy by STS. Our measurements show that the electronic properties of adsorbed molecules depend significantly on their respective bonding mechanism (chemisorption or physisorption). The bonding mechanism on the other hand is determined by molecular properties (electrophilicity and aromaticity) as well as surface properties (dimer structure and stoichiometry). Based on these insights into the nature of organic/inorganic bonding mechanisms we are extending our investigations to the characterization of organic adsorbate layers on other III-V materials and particularly group-III nitrides (InN, GaN, InGaN) and 2D nano-materials, e.g. 2D silicon. For this purpose well defined III-nitride surface structures are needed. We therefore explore the atomic surface structure of these materials upon subsequent molecule adsorption. On InxGa1-xN (0001) (0≤x≤1) we established the preparation of clean reconstructed surfaces with (1x1), (1+1/6), (2x2) and (√3x√3)R30°

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symmetries under ultra-high vacuum conditions. The amount of surface-indium determines the atomic and electronic structure of these surfaces giving rise to also influence the interface formation with molecular layers.

Left: UV-RAS spectra of pyrrole adsorbed on GaAs(001)(4x2) (orange line) and the clean GaAs surface (grey line). Right: Single molecule STS spectrum of adsorbed pyrrole (shown in the inset STM image) indicating possible UV transitions that could contribute to the UV-RAS anisotropies.

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9.4.3 Books

Blue and green-emitting laser diodes Michael Kneissl & Jens Raß book chapter to be published in Landolt-Börnstein VIII-Vol. B Part III – Laser System (2010). – IN PRINT.

9.4.4 Publications

1. Emission characteristics of InGaN multi quantum well light emitting diodes with

differently strained InAlGaN barriers T. Kolbe, A. Knauer, H. Wenzel, S. Einfeldt, V. Küller, P. Vogt, M. Weyers, M. Kneissl phys. stat .sol. (c) 6, No. S2, S889-S892 (2009)

2. Optimization of InGaN/(In,Al,Ga)N based near UV-LEDs by MQW strain balancing with in-situ wafer bow sensor A. Knauer, T. Kolbe, S. Einfeldt, M. Weyers, M. Kneissl, and T. Zettler phys. stat .sol. (a) 206, 211-214 (2009)

3. Epitaxial Lateral Overgrowth on (2-1-10) a-Plane GaN with [0-111] Oriented Stripes T. Wernicke, U. Zeimer, C. Netzel, F. Brunner, A. Knauer, M. Weyers, M. Kneissl J. Crystal Growth 311, 2895(2009)

4. MOVPE growth for UV-LEDs A. Knauer, F. Brunner, T. Kolbe V. Küller, H. Rodriguez. S. Einfeldt, M. Weyers and M. Kneissl Proc. SPIE 7231, 72310G (2009)

5. Ultraviolet laser diodes on AlN and sapphire substrates Michael Kneissl, Zhihong Yang, Mark Teepe, Noble M. Johnson Proc. SPIE 7230, 7230-13 (2009)

6. Growth mode of InGaN on GaN (0001) in MOVPE M. Pristovsek, J. Stellmach, M. Leyer, M. Kneissl phys. stat .sol. (c), 1– 5 (2009) / DOI 10.1002/pssc.200880915

7. Volmer-Weber growth mode of InN quantum dots on GaN by MOVPE Christian Meissner, Simon Ploch, Markus Pristovsek, Michael Kneissl phys. stat .sol. (c), 6, S2, S545 (2009). (DOI 10.1002/pssc.200880872)

8. Growth Mode and Shape of InN Quantum Dots and Nanostructures grown by Metal Organic Vapour Phase Epitaxy S. Ploch, C. Meissner, M. Pristovsek, M. Kneissl phys. stat .sol. c 6, s574 (2008)./ DOI 10.1002/pssc.200880938

9. Adsorption geometry of hydrocarbon ring molecules on GaAs(001)c4x4 R. Paßmann, T. Bruhn, T.A. Nilson, B. O. Fimland, M. Kneissl, N. Esser, P.Vogt Phys. Status Solidi B 246 (Feature Article), 1504-1509 (2009) /DOI 10.1002/pssb.200945178

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10. Bonding configuration of cyclopentene on InP(001)(2x4) surface Regina Passmann, Priscila Favero, Wolf Gero Schmidt, Ronei Miotto, Walter Braun, Wolfgang Richter, Michael Kneissl, Norbert Esser and Patrick Vogt Phys. Rev. B 80, 125303 (2009)

11. Polarization of eigenmodes in laser diode waveguides on semipolar and nonpolar GaN Jens Raß Tim Wernicke, Wolfgang G. Scheibenzuber, Ulrich T. Schwarz, Jan Kupec, Bernd Witzigmann, Patrick Vogt, Sven Einfeldt, Markus Weyers, Michael Kneissl phys. stat. sol. (RRL) 4, 1-3 (2010). (DOI 10.1002/pssr.200903325)

12. Adsorption of cyclopentene on GaAs(001) and InP(001), a comparative study by synchrotron-based core level spectroscopy R. Paßmann, T. Bruhn, B. O. Fimland, W. Richter, M. Kneissl, N. Esser, P. Vogt World Scientific WSPC - Proceedings of the workshop on synchrotron radiation and nano-structures 1, (2009), ISBN-13: 978-981-4280-83-9

13. Structure investigations of nonpolar GaN layers W. Neumann, A. Mogilatenko, T. Wernicke, E. Richter, M. Weyers, M. Kneissl J. Microsc. 237, 308 (2009)

14. Deep UV nitride-based light emitting diodes – applications and challenges M. Kneissl, T. Kolbe, N. Lobo, J. Stellmach, A. Knauer, V. Küller, H. Rodriguez, S. Einfeldt, M. Weyers Proceedings of the 6th China International Forum on Solid State Lighting (2009)

15. Laser Scribing for Facet Fabrication of InGaN MQW Diode Lasers on Sapphire Substrates J. R. van Look, S. Einfeldt, V. Hoffmann, A. Knauer, M. Weyers, P. Vogt and M. Kneissl IEEE Photonics Technology Letters 22 (6), 416 (2010)

16. Adsorbate-induced modification of the surface electric field at GaAs(001)-c(4x4) measured via the linear electro-optic effect T. Bruhn, R. Paßmann, B. O. Fimland, M. Kneissl, N. Esser, P. Vogt phys. stat. sol. (b) 247 (8), 1941 (2010).

17. Internal efficiency of InGaN light-emitting diodes: Beyond a quasi-equilibrium model W. W. Chow, M. H. Crawford and J. Y. Tsao, M. Kneissl Appl. Phys. Lett. 97, 121105 (2010).

18. InGaN/GaN Disk Laser for Blue-Violet Emission Wavelengths R. Debusmann, N. Dhidah, V. Hoffmann, L. Weixelbaum, U. Brauch, T. Graf, M. Weyers, M. Kneissl IEEE Photonics Technology Letters 22 (9), 652 (2010).

19. Growth of semipolar (10-1-3) InN on m-plane sapphire using MOVPE Duc Dinh, M. Pristovsek, R. Kremzow, M. Kneissl phys. stat. sol. (RRL) 4, No. 5–6, 127 (2010).

20. Well width study of InGaN multiple quantum well structures for blue-green emitters V. Hoffmann, C. Netzel, U. Zeimer, A. Knauer, S. Einfeldt, F. Bertram, M. Weyers, G. Tränkle, M. Kneissl J. of Crystal Growth (2010), doi:10.1016/j.jcrysgro.2010.09.013

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21. Uniformity of the wafer surface temperature during MOVPE growth of GaN-based laser diode structures on GaN and sapphire substrate V. Hoffmann, A. Knauer, C. Brunner, S. Einfeldt, M. Weyers, G.Tränkle, K. Haberland, J.-T. Zettler, M. Kneissl J. of Crystal Growth (2010), doi:10.1016/j.jcrysgro.2010.09.048

22. Advances in InAlGaN-based deep UV light emitting diode technologies M. Kneissl, T. Kolbe, N. Lobo, J. Stellmach, A. Knauer, V. Kueller, H. Rodriguez, S. Einfeldt, M. Weyers Proceedings of the 12th International Symposium on the Science and Technology of Light Sources and the 3rd International Conference on White LEDs and Solid State Lighting, LS-WLED 2010, 265-268 (2010).

23. (In)AlGaN deep ultraviolet light emitting diodes with optimized quantum well width T. Kolbe, T. Sembdner, A. Knauer, V. Küller, H. Rodriguez S. Einfeldt, P. Vogt, M. Weyers and M. Kneissl phys. stat. sol. (a) 207, 2198-2200 (2010).

24. Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes T. Kolbe, A. Knauer, C. Chua, Z. Yang, H. Rodrigues, S. Einfeldt, P. Vogt, N.M. Johnson, M. Weyers and M. Kneissl Appl. Phys. Lett. 97, 171105 (2010).

25. Carrier injection in InAlGaN single and multi-quantum-well ultraviolet light emitting diodes T. Kolbe, T. Sembdner, A. Knauer, V. Küller, H. Rodriguez S. Einfeldt, P. Vogt, M. Weyers and M. Kneissl phys. stat. sol. (c) 7, 2196-2198 (2010).

26. Metalorganic Vapor Phase Epitaxy of InN on GaN using tertiary-butylhydrazine as Nitrogen Source R. Kremzow, M. Pristovsek, J. Stellmach, Ö. Savaş, M. Kneissl Journal of Crystal Growth (2010), DIO:10.1016/j.jcrysgro.2010.03.019

27. Growth of AlGaN and AlN on Patterned AlN/Sapphire Templates V. Küller, A. Knauer, F. Brunner, U. Zeimer, H. Rodriguez, M. Weyers, and M. Kneissl Journal of Crystal Growth (2010), doi:10.1016/j.jcrysgro.2010.06.040

28. Enhancement of light extraction in UV LEDs using nanopixel contact design with Al reflector N. Lobo, H. Rodriguez, A. Knauer, M. Hoppe, S. Einfeldt, P. Vogt , M. Weyers and M. Kneissl Appl. Phys. Lett. 96, 081109 (2010).

29. Effects of low charge carrier wave function overlap on internal quantum efficiency in GaInN quantum wells Carsten Netzel, Veit Hoffmann, Tim Wernicke, Arne Knauer, Markus Weyers, Hans Wenzel, and Michael Kneissl phys. stat. sol. (c) 7, 1872 (2010).

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30. Influence of the wave function overlap in GaInN quantum wells on the temperature and excitation power dependent photoluminescence intensity C. Netzel, V. Hoffmann, T. Wernicke, A. Knauer, M. Weyers, M. Kneissl, and N. Szabo Journal of Applied Physics 107, 033510 (2010).

31. Orientation control of GaN {11-22} and {10-13} grown on (10-10) sapphire by metal-organic vapor phase epitaxy S. Ploch, M. Frentrup, T. Wernicke, M. Pristovsek, M. Weyers, M. Kneissl J Cryst. Growth, 312, 2171 (2010).

32. Determination of the complex linear electro-optic coefficient of GaAs and InP M. Pristovsek physica status solidi (b) 247 (2010) 1974-1978 DOI:10.1002/pssb.200983950

33. Facet formation for laser diodes on nonpolar and semipolar GaN Jens Raß, Tim Wernicke, Raimund Kremzow, Wilfred John, Sven Einfeldt, Patrick Vogt, Markus Weyers, Michael Kneissl phys. stat. sol. (a) 207, 1361–1364 (2010) / DOI 10.1002/pssa.200983425

34. GaN-based Ultraviolet Light-Emitting Diodes with Multifinger Contacts H. Rodriguez, N. Lobo, S. Einfeldt, A. Knauer, M. Weyers and M. Kneissl phys. stat. sol. (a), (2010), DOI: 10.1002/pssa.201026193

35. Application of GaN-based deep ultraviolet light emitting diodes – UV-LEDs – for Water disinfection M.A. Würtele, T. Kolbe, A. Külberg, M. Lipsz, M. Weyers, M. Kneissl, M. Jekel Water Research 45, 1481 (2011).

36. Optical and structural properties of InGaN/(AlIn)GaN multiple quantum wells grown at different temperatures and In supply U. Zeimer, U. Jahn, V. Hoffmann, M. Weyers, M. Kneissl Journal of Electronic Materials, Vol. 39, 677 (2010),

37. High aluminium content and high growth rates of AlGaN in a close-coupled showerhead MOVPE reactor J. Stellmach, M. Pristovsek, Ö. Savas, J. Schlegel, E. V. Yakovlev, M. Kneissl Journal of Crystal Growth 315, 229 (2011).

38. MOCVD growth of InGaN/GaN QDs for green emitters A. Kadir, Ch. Meissner T. Schwaner, M. Pristovsek, M. Kneissl Proc. of the Photonics 2010. New Delhi: Viva Books Private Ltd, 2010, S. 231-231

39. Surface morphology of homoepitaxial GaN grown on non and semipolar GaN substrates Tim Wernicke, Simon Ploch, Veit Hoffmann, Arne Knauer, Markus Weyers, and Michael Kneissl phys. stat. sol. (b) 248, No. 3, 574 (2011).

40. Crystall orientation of GaN layers on (10-10) Sapphire M. Frentrup, S. Ploch, M. Pristovsek, M. Kneissl phys. stat. sol. (b) 248, No.3, 583 (2011)

41. Application of GaN-based deep ultraviolet light emitting diodes – UV-LEDs – for Water disinfection M.A. Würtele, T. Kolbe, A. Külberg, M. Lipsz, M. Weyers, M. Kneissl, M. Jekel Water Research 45, 1481 (2011).

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42. Advances in group III-nitride based deep UV light emitting diode technology M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, Z. Yang, N. M. Johnson, M. Weyers Semicond. Sci. Technol. 26, 014036 (2011).

43. Adsorbate-induced modification of the surface band bending at GaAs(001) surfaces T. Bruhn, B. O. Fimland, M. Kneissl, N. Esser, P. Vogt Phys. Rev. B 83, 045307 (2011)

44. High aluminium content and high growth rates of AlGaN in a close-coupled showerhead MOVPE reactor J. Stellmach M. Pristovsek, Ö. Savas, J. Schlegel, E. V. Yakovlev, M. Kneissl Journal of Crystal Growth 315, 229 (2011).

45. Polarization dependent photoluminescence studies of semipolar and nonpolar InGaN quantum wells L. Schade, U.T. Schwarz, T. Wernicke, M. Weyers, M. Kneissl phys. stat. sol. (b) 248, No.3, 638 (2011).

46. Growth Mechanism of Embedded Self-Organized InN Quantum Dots on GaN (0001) in MOVPE F. Ivaldi, J. Domagala, S. Kret, Ch. Meissner, M. Pristovsek, M. Högele, and M. Kneissl Jpn. J. of Appl. Phys. 50, No. 3, 031004 (2011).

47. Optical polarization of UV-A and UV-B (In)(Al)GaN multiple quantum well light emitting diodes T. Kolbe, A. Knauer, J. Stellmach, C. Chua, Z. Yang, H. Rodrigues, S. Einfeldt, P. Vogt, N.M. Johnson, M. Weyers and M. Kneissl Proc. SPIE 7939, 79391G (2011).

48. AlGaN-based Ultraviolet Lasers - Applications and Materials Challenges Michael Kneissl, Tim Kolbe, Jessica Schlegel, Joachim Stellmach, Chris Chua, Zhihong Yang, Arne Knauer, Markus Weyers, Noble M. Johnson Technical Digest, CLEO: 2011 (Optical Society of America, Washington, DC, 2011), JTuB1 (2011).

49. In-situ optical spectroscopy and electronic properties of pyrrole sub-monolayers on Ga-rich GaAs(001) T. Bruhn, B. O. Fimland, M. Kneissl, N. Esser, P. Vogt J. Nanoparticle Research (2011) , DOI: 10.1007/s11051-011-0340-0

50. Direct observation of dimer flipping at H-terminated InP and GaP (001) surfaces P. Kleinschmidt, H. Döscher, P. Vogt, T. Hannappel Phys. Rev. B 83, 155316 (2011)

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9.4.5 Invited Talks

Prof. Dr. Michael Kneissl Ultraviolet Laser Diodes on AlN and Saphire Substrats SPIE Photonics West 2009, San Jose, Germany, January 2009

Prof. Dr. Michael Kneissl Semiconductor Nanophotonics Research at TU Berlin Seminar at Middle East Technical University (METU), Ankara, Turkey, April 2009

Prof. Dr. Michael Kneissl Deep UV nitride-based light emitting diodes Applications and Challenges China Solid State Lighting Conference 2009, Shenzen, China, October 2009

Prof. Dr. Michael Kneissl Ultraviolet LEDs and Lasers - Applications and ChallengesiNOW 2009, Stockholm, Sweden, August 2009

Prof. Dr. Michael Kneissl From UV LEDs to green lasers – Challenges and progress in the development of GaN based light emitters Seminar at Varian Semiconductor Equipment Associates, Gloucester, MA, USA, November 2009

Prof. Dr. Michael Kneissl MOVPE of (In)AlGaN materials for UV light emitters Aixtron Workshop 2009, Shenzen, China, October 2009

Prof. Dr. Michael Kneissl Advances in InAlGaN-based deep UV light emitting diode technologies 3rd International Conference on White LEDs and Solid State Lighting LS12-WhiteLED3, Eindhoven, Netherlands, July 2010

Prof. Dr. Michael Kneissl Advances and applications of GaN-based UV light emitting diode technologies International Nano-Optoelectronics Workshop (iNOW 2010), Beijing, China, August 2010

Prof. Dr. Michael Kneissl Group III-nitride based UV light emitters – applications and materials challenges Seminar at the Paul Drude Institut für Festkörperelektronik, Berlin, Germany, March 2010

Prof. Dr. Michael Kneissl InAlGaN-based UV LEDs - Applications and Challenges Physikalisches Kolloquium, Otto-von-Guericke University, Magdeburg, Germany, May 2010

Prof. Dr. Michael Kneissl Fortschritte bei der Entwicklung von LEDs im ultravioletten Spektralbereich VDI Fachtagung LED, Düsseldorf, Germany, November 2010

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Prof. Dr. Michael Kneissl LEDs im fernen UV - Stand und mögliche Anwendungen FutureLED Workshop, Berlin, Germany, May 2010

Dr. Abdul Kadir Growth mechanism of InGaN quantum dots by metalorganic vapour phase epitaxy Alexander von Humboldt Network Meeting, Duisburg, April 2010

Dr. Markus Pristovsek Advanced In-situ Monitoring of Metal Organic Vapour Phase Epitaxy SemicoNano, Tokushima, Japan, August 2009

Dr. Markus Pristovsek Metal-Organic Vapour Phase Epitaxy of Indium Nitride Universidad Politécnica de Madrid (ETSIT-UPM), Madrid, Spain, August 2010

Dr. Markus Pristovsek In-situ Monitoring of Doping with Reflectance Anisotropy Spectrocopy 3rd NanoCharm Workshop on Non-Destructive Real Time Process Control, Berlin, Germany, October 2010

Dr. Patrick Vogt Adsorption of small organic ring molecules on III-V(001) surfaces Epioptics-11, Erice, Italy, July 2010

Dr. Patrick Vogt Organic/inorganic interfaces: basic concepts Epioptics-11, Erice, Italy, July.2010

Dr. Patrick Vogt Devices based on InGaAs Quantum Dots PV-Technology Development & Market-Trends, National Technical University of Athens (Ethniko Metsovio Polytechnio), Athinai (Athen), Greece, October 2010

Dr. Patrick Vogt Growth and Characterization of In(Ga)N Compounds for Device Applications PV-Technology Development & Market-Trends, National Technical University of Athens (Ethniko Metsovio Polytechnio), Athinai (Athen), Greece, October 2010

Dr. Tim Wernicke Growth of nonpolar nitrides: the substrate dilemma DPG Frühjahrstagung 2009, Dresden, Deutschland, March 2009

Dr. Tim Wernicke Growth of nonpolar nitrides: the substrate dilemma Seminar at the University of Cambridge, UK, July 2009

Dr. Tim Wernicke In-incorporation on semipolar surfaces for blue-green lasers Seminar at the IAF, Freiburg, July 2010

Dr. Tim Wernicke In-incorporation on semipolar surfaces for blue-green lasers E-MRS Fall meeting, Warschau, Poland, September 2010

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Dr. Tim Wernicke Semipolar quantum wells for lasers PolarCoN Summerschool, Ulm, Germany, October 2010

Dipl.-Phys. Tim Kolbe Water disinfection with GaN-based deep ultraviolet light emitting diodes nANO meets water II, Oberhausen, Germany, Fraunhofer UMSICHT, November 2010

Dipl.-Phys. Simon Ploch Growth of semipolar InN, GaN and AlN on m-plane sapphire PolarCoN Summerschool, Günzburg, Germany, October 2010

116

9.4.6 Diploma, Master-, and Bachelor Theses

Eric Bauch Nitrogen-Vacancy defects in diamond for sub-millimeter

magnetometry 28.07.2010

Amelie Biermann Morphologie und atomare Struktur von In(Ga)N Oberflächen 12.10.2010

Martin Frentrup Epitaxie und Charakterisierung von nicht- und semipolaren Galliumnitrid-Heterostrukturen 17.03.2010

Marc Hoffmann GaAs-basierte Tunneldioden 18.07.2009

Michael Högele Epitaxie und Charakterisierung von InGaN Quantenpunktstrukturen 30.10.2009

Michael Hoppe Elektrooptische und elektrothermische Untersuchungen an Leuchtdioden im ultravioletten Spektralbereich 03.09.2010

André Kruse Wachstumsmodi von InGaN Schichten in der Metallorganischen Gasphasenepitaxie 28.07.2010

Igor Kuznecov Metallorganische Gasphasenepitaxie von AlGaN-Schichten mit hohem Aluminiumgehalt 12.11.2010

Martin Martens Optoelektronische Eigenschaften und spektrale Empfindlichkeit von AlGaN-basierten Photodetektoren 03.09.2010

Linda Riele Bindungsstruktur und Selbstorganisation von Metall-Phtalocyaninen auf GaAs(001)-Oberflächen 10.10.2009

Özgür Savas Dotierung und Charakterisierung von (Al)GaN Schichten hergestellt mittels Metallorganischer Gasphasenepitaxie 06.05.2009

Matthias Schmies In-Situ Rastertunnelmikroskopie an Nanostrukturen in der Metallorganischen Gasphasenexpitaxie 02.03.2010

Katrin Sedlmeier CuInxGa(1-x) Se2 Nanokristalle: Wachstum mittels chemischer Gasphasenabscheidung und Charakterisierung 11.08.2010

Toni Sembdner Analyse der Lumineszens- und Strom-Spannungs-Charakteristik von Lichtemittern im UV Spektralbereich 17.03.2010

Alexander Wolf, B.Sc. Charakterisierung von AlGaN-basierten MSM Photodetektoren mit unterschiedlichen Fingerkontakt-Geometrien 21.12.2010

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