Catalyst-free PLD Growth of Self-forming Moth-eye ZnO Nanostructure Arrays for IR Anti-Reflection Applications

F. Hosseini Teherania*, D. J. Rogersa, P. Bovea and M. Razeghib

aNanovation, 8 route de Chevreuse, 78118, France bCenter for Quantum Devices, Northwestern University, Evanston, Illinois 60208, USA

BIOGRAPHY Dr Ferechteh Hosseini Teherani: has been involved with the development

of novel oxide materials and devices for over 25 years. After receiving her PhD from the University of Paris, Dr Teherani was a researcher at Thales (France), Nippon Telephone & Telegraph (Japan), Electrotechnical Laboratory (Japan) and Northwestern University (USA). In 2001, she went on to found a startup, Nanovation, of which she is currently CEO. Nanovation develops and commercialises ZnO thin films and nanostructures for optoelectronic applications. Dr. Teherani also has an MBA, has held an Eshbach Visiting Scholarship at Northwestern University and has been an expert for the European Commission since 2005. Dr. Teherani is author/co-author of over 115 papers and 8 patents.

TECHNICAL ABSTRACT ZnO is wide bandgap material, which is being widely adopted as a transparent electrode thanks to biocompatibility, low cost and transparencies/conductivities rivalling those of Indium Tin Oxide [1]. ZnO also exhibits one of the largest families of nanostructures of all materials systems. Indeed, ZnO is one of the most researched nanomaterials and it is forecast to play an important role in a whole range of emerging optoelectronic applications. In previous studies [2,3] it was demonstrated that Pulsed Laser Deposition (PLD) can give catalyst-free, self-forming and vertically-aligned nanostructure arrays with superior crystallinity and optical quality. The fact that these structures were self-forming and did not require a metal catalyst simplifies the manufacturing and subsequent device fabrication. It was found that different nanostructure morphologies could be obtained by PLD including vertical, tapering and broadening nanostructures. Amongst these, the tapering “moth-eye type” arrays (see figure) have shown excellent anti-reflection properties (<0.5% reflection) extending into the infra-red [4] for incidence angles up to over 60º which predispose them for use in detector/sensor, solar cell and LED applications.

Figure: Scanning Electron Microscope Image showing self-forming, catalyst-free ZnO moth-eye nanostructure

arrays grown by PLD

500nm

Although PLD gives nanostructures with excellent optical quality, the anisotropic plasma plume creates an inhomogeneous growth. This paper reports on the development of an approach to give uniform ZnO nanostructure array growth by PLD over 2 inch diameter wafers.

References

[1] D. J. Rogers and F. Hosseini Teherani Encyclopedia of Materials: Science and Technology, Elsevier, Oxford (2010) 1-5. [2] V. E. Sandana et al. J. Vac. Sci. Technol. B 27 (2009) 3, [3] D. J. Rogers et al. Proc. of SPIE Vol. 7217 (2009) 721708-1 [4] M. Peres et al. Phys. Status Solidi B, 247, 7 (2010) 1695-1698

Keywords: ZnO, nanostructure, moth-eye, anti-reflection, transparent conductor,

*fht@nanovation.com; phone +33 6 50 81 08 36