Nanoscience and Energy Allen Hermann, Ph.D.

Professor of Physics Emeritus, University of Colorado

Boulder, Colorado 80309-0390 USA

allen.hermann@colorado.edu

Lecture 1. Course Introduction and Definitions

History, and examples

in nature and man-made

Quantum nature- theory:

quantum confinement

Nanomaterials: Dimensionality

Chemical varieties and shapes

Synthesis

Top-down: Lithography

Bottom-up: Self-assembly

Characterization and Handling

Measurements

Nanotemplates

Lecture 2. Nanocarbon C60, CNT’s

Synthesis and e-beam lithography

Graphene (synthesis, relativistic

QM nature, transport)

Lecture 3. Energy and Nanotechnology Review of Alternate Energy

Sources

Review of Electronic Properties of

Solids:

Free- electron Fermi gas

Energy bands in Solids

Semiconductors and doping

pn junctions

Amorphous semiconductors

Lecture 4. Solar cells: Motivation (examples) and Theory pn junctions under illumination

Homojunctions

Open-circuit voltage, short-

circuit current

IV curve, fill factor, solar-to-

electric conversion efficiency

Carrier generation and

recombination

Defects and minority carrier

diffusion

Current due to minority carrier

diffusion:

Solution to the diffusion

differential equation under

Spatially-homogeneous

generation, and

under Inhomogeneous

generation

Effect of an electric field

Heterojunctions

Lecture 5. Experiment: Types of Solar Cells

•Generation I solar cells:

Single Crystal Si, Polycrystalline Si

Growth, impurity diffusion, contacts, anti-reflection coatings

•Generation II Solar cells:

Polycrystalline thin films, crystal structure, deposition techniques

CdS/CdTe (II-VI) cells

CdS/Cu(InGa)Se2 cells

Amorphous Si:H cells

•Generation III Solar Cells:

•High-Efficiency Multijunction Concentrator Solar cells based on

III-V’s and III-V ternary analogues

•Dye-sensitized solar cell

•Organic (excitonic) cells

•Polymeric cells

•Nanostructured Solar Cells including Multicarrier per photon cells,

quantum dot and quantum-confined cells

Lecture 6. Nanotechnology Fuel Cells

Nano-composite materials

Nanoelectronics and photonic

Devices:

Chemical and Biological Detectors

Nanomedicine:

Disease Detection

Implants

Delivery of Therapeutics

Other nanomedicine

Applications

Risks

Lecture 7. Other Nanotechnology Applications DNA sequencing

Filtration

Clothing and Sports

Composites

Other Nanomedicine Applications and Opportunities

Other Nanotemplate-based Applications:

Superconductors

Magnetic Nanowires

Ferroelectrics

Dielectric Nanostructures and Cloaking

The Business of Nanotechnology

Basis for Grade in the Course

Your grade in the course is based on 2 factors:

1) class attendance 2)grade earned on the paper

assigned.

A 1-2 page paper in English is to be turned in to Prof. Hermann by the end of the last lecture. Both a hard

copy and a digital copy emailed to allen.hermann@colorado.edu

are required. This paper should be in your own words.

The paper could contain one or more figures and/or tables.

The subject matter should be either 1) a tutorial explaining clearly one topic from this

course (in greater detail than given in the course), or 2) a clear description of your own research related

to the subject of this course.

Your grade will be calculated as follows: Attendance- 40% ( 5.71 % per class attended) Grade for paper- 60%

Further References1. Charles Kittel, “Introduction to Solid State Physics”, Prentice Hall (1967 ff.)2. S.M. Sze, “Physics of Semiconducting Devices”, John Wiley (1969,ff.)3.Frank Larin, “Radiation Effects in Semiconducting Devices” (John Wiley)4. H.Y. Tada and J.R. Carter, JPL Solar cell Radiation handbook, NASA (1977)5. Martin Green, “Solar Cells”, Prentice Hall (1982,ff.)6. H.J. Hovel, “Solar Cells”, in Semiconductors and Semimetals, Vol.11 (edited by R. Richardson and A. Beer, Academic Press, 1975).7. J. Reynolds and A. Meulenberg, J.Appl. Phys. 45, 2582(1974)

Lecture 1

Course Introduction and Definitions

Lecture 1. Course Introduction and Definitions

History, and examples

in nature and man-made

Quantum nature- theory:

quantum confinement

Nanomaterials: Dimensionality

Chemical varieties and shapes

Synthesis

Top-down: Lithography

Bottom-up: Self-assembly

Characterization and Handling

Measurements

Nanotemplates

10,000 Kilometers

1000 km

Sliding scale universe: http://htwins.net/scale2/scale2.swf?bordercolor=white

What is Nanotechnology?

• Research and technology development at the atomic, molecular

or macromolecular levels, in the length scale of approximately 1 - 100 nanometers.

• Creating and using structures, devices and systems that have novel properties and functions because of their small and/or intermediate size.

• Ability to control processes at a few nm-range for advanced material processing and manufacturing.

Red blood cells (~7-8 mm)

DNA

~2-1/2 nm diameter

Things Natural Things Manmade

Fly ash ~ 10-20 mm

Atoms of silicon spacing ~tenths of nm

Head of a pin 1-2 mm

Quantum corral of 48 iron atoms on copper surface positioned one at a time with an STM tip

Corral diameter 14 nm

Human hair ~ 60-120 mm wide

Ant ~ 5 mm

Dust mite

200 mm

ATP synthase

~10 nm diameter Nanotube electrode

Carbon nanotube ~1.3 nm diameter

O O

O

OO

O OO O OO OO

O

S

O

S

O

S

O

S

O

S

O

S

O

S

O

S

PO

O

The Challenge

Fabricate and combine nanoscale building blocks to make useful devices, e.g., a photosynthetic reaction center with integral semiconductor storage.

Mic

row

orl

d

0.1 nm

1 nanometer (nm)

0.01 mm

10 nm

0.1 mm

100 nm

1 micrometer (mm)

0.01 mm

10 mm

0.1 mm

100 mm

1 millimeter (mm)

1 cm

10 mm 10-2 m

10-3 m

10-4 m

10-5 m

10-6 m

10-7 m

10-8 m

10-9 m

10-10 m

Vis

ible

Nan

ow

orl

d

1,000 nanometers = In

frar

ed

U

ltra

vio

let

M

icro

wav

e S

oft

x-r

ay

1,000,000 nanometers =

Zone plate x-ray “lens” Outer ring spacing ~35 nm

The Scale of Things – Nanometers and More

MicroElectroMechanical (MEMS) devices 10 -100 mm wide

Red blood cells Pollen grain

Carbon buckyball

~1 nm diameter

Self-assembled,

Nature-inspired structure

Many 10s of nm

My Personal Early Nanotechnology Motivation

Li LiI

PVP-I CT complex

Li+

20 nm nanorods of MnO2 for positive electrodes

in Li ion batteries

• Quantum Confinement

• One Dimension

• Quantum Confinement

• Three Dimensions

For absorption, energy of photon absorbed goes

as 1/L2, smaller particle absorbs larger

energy photon, who’s wavelength is smaller (toward blue), and longer wavelength photons (toward red)

are transmitted.

Figure 7.2. Solutions of quantum dots of varying size. Note the variation

in color of each solution illustrating the particle size dependence of the

optical absorption for each sample. Note that the smaller particles are in

the red solution (absorbs blue), and that the larger ones are in the blue

(absorbs red).

For light scattering, the photon wavelength must be

smaller than the particle size, and the smaller particles tend to

scatter only the shorter wavelength photons (toward blue)

.Nanomaterials

• C. Dimensionality

• D. Chemical varieties

• E. Shapes

• F. Synthesis

– 1. Lithography

– 2. self-assembly

• Synthesis

1. Lithography

Developing Positive Negative

Etching and Stripping

Polymer Resist

Thin Film Substrate

Resist Resist

Exposing Radiation

Figure 1.1. Schematic of positive and negative resists.

Figure 1.6. Schematic of a focused ion beam system.

1 mm

400 nm

300 nm

200 nm

160 nm

120 nm

100 nm

80 nm

60 nm100 nm

Carbon Nanotubes/Nanocones with Various Catalyst Patterning Dimensions by E-beam Lithography

Figure 2.1. The process of forming a self-assembled monolayer. A

substrate is immersed into a dilute solution of a surface-active

material that adsorbs onto the surface and organizes via a self-

assembly process. The result is a highly ordered and well-packed

molecular monolayer. (Adapted from Ref. 9 by permission of

American Chemical Society.)

.Characterization and Handling

– a. Optical Tweezers

– b. Electromagnetic tweezers

– c. In nanotemplates

– d. Structural Analysis by TEM, SEM, X-ray, etc.

Ballistic Nanotube MOS Transistors (Chen,Hastings)

Wd

D

L

SWNTSWNT

SiO2

Source

Al-Gate

Ti

HfO2

Drain

L

L~20 L~20 nmnm

Placement of Nanotubes by E-Field

(The first-demo) Nanotube Field-Effect Transistor(FET)

E-Beam Lithography

• Measurements

Figure 3.1. Schematic showing all major components of an SPM. In

this example, feedback is used to move the sensor vertically to

maintain a constant signal. Vertical displacement of the sensor is

taken as topographical data

Coarse approach

mechanism

S

c

a

n

n

e

r

Sensor

Sample

Reference

-

Signa l

feedback

data

Figure 3.1. Schematic showing all major

components of an SPM. In this example,

feedback is used to move the sensor

vertically to maintain a constant signa l.

Vertical displacement of the sensor is takenas topograph ical data.

Major equipment

• Focused Ion Beam System (FIB) (scheduled for installation in mid 2007) • Atomic Layer Deposition System (ALD) • Rapid Thermal Processing System (RTP) • Plasma Enhanced Chemical Vapor Deposition System (PECVD) • Standard Resolution Electron Beam Lithography (EBL) • Atomic Force Microscope for Nanopatterning, and Manipulation (AFM) • Atomic Force Microscope for Atomic Resolution Imaging (AFM) • Quartz Crystal Microbalance (QCM) • 4-furnace bank of 3-zone oxidation, dopant diffusion, and annealing furnaces • Class 100 Clean Room • Spin-Coating Station • Photolithography System • Surface Profiler • Chemical Treatment Station (cleaning, etching, and functionalization) • Ion Milling System • Plasma Cleaning/Oxidation System • Gas Cabinet Bank • Experimental Materials Thermal Evaporator • Standard Materials Thermal Evaporator • Electron-Beam Evaporator • Multi-target Sputtering System • Probe Station and Device Characterization System • Four-Point Resistance Measurement System • Ellipsometer • Optical Microscopes • Dicing Saw • Equipment Cooling Systems (3) • Inductive Coupled Plasma (ICP) Etching System (scheduled for installation in Feb. 2006) • Experimental materials sputtering system (scheduled for installation in mid 2006) • Ultra-High Resolution EBL and SEM System

Clean Room

Photolithography

Rapid Thermal

Processing

Quartz MicroBalance

Plasma

Enhanced

Chemical

Vapor

Deposition

Reactive Ion Etching

Atomic

Layer

Deposition

IV. Nanotemplates

• G. Inorganic

• H. Organic

Fig.2 (a) Nanostructure of anodically formed Al2O3 template. (b) its cross-section, (c) catalyst deposited at the bottom of the pores, (e) vertically aligned nanotubes, and (f) TEM

image of a nanotube.

(Chen, Singh, DeLong, Saito, Yang, Bhattacharyya, and Sumanasekeras)

Nano-scale Material Research

(a)

(b)

(c)

Catalyst

200nm200 nm

Vertically aligned MWNTs

embedded in AAO insulator

(d)

Si substrate

SiO2

SiO2

Carbon nanotubes

AlSiO2

Hexagonal Cells

Nano-template

Horizontally

aligned

The first vertically aligned nanotubes on silicon substrates using templates

• Fig. 3 Schematic representing the helix-coil transitions within the pore of a Poly-L-Glutamic Acid functionalized membrane (a) random-coil formation at PH > 5.5 , (b) helix formation at low pH ( <4 ).