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Conductivity, photoconductivity and optical properties of amorphous GaN films

Published online by Cambridge University Press:  21 March 2011

A. Koo ,
U. D. Lanke ,
B. J. Ruck ,
S. A. Brown ,
R. Reeves ,
I. Liem ,
A. Bittar  and
H. J. Trodahl
A. Koo
Affiliation:
School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
U. D. Lanke
Affiliation:
School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
B. J. Ruck
Affiliation:
School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
S. A. Brown
Affiliation:
Nanostructure Engineering Science and Technology Group and Department of Physics and Astronomy, University of Canterbury, Christchurch, New Zealand
R. Reeves
Affiliation:
Nanostructure Engineering Science and Technology Group and Department of Physics and Astronomy, University of Canterbury, Christchurch, New Zealand
I. Liem
Affiliation:
Nanostructure Engineering Science and Technology Group and Department of Physics and Astronomy, University of Canterbury, Christchurch, New Zealand
A. Bittar
Affiliation:
Measurement Standards Laboratory, Industrial Research Limited, Lower Hutt, New Zealand
H. J. Trodahl
Affiliation:
School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
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Abstract

It has been predicted that amorphous GaN has a low density of states in the gap, and therefore has potential as a useful opto-electronic material in the blue-green spectral region. We have synthesised amorphous GaN films on various substrates by ion assisted deposition and investigated the effects of sample preparation conditions on the conducting and optical properties. The room temperature resistivity ρ0 of stoichiometric (Ga:N of 1:1) films is above 105 Ω cm, and these films exhibit a complex form for the temperature dependence of the resistivity. Films having an excess of Ga show a much lower ρ0. The optical absorption shows ar 0 band-gap of 3 eV, with the gap falling below that value when the amorphous network incorporates homopolar (Ga-Ga) bonds. The best films are thus transparent across the visible region with a low density of gap states, undetectable in optical absorption. The photoluminescence spectra obtained from these a-GaN films consist of a broad green light emission peaking at 528 nm. Preliminary photoconductivity measurements show sensitivity in the UV.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 693 , 2001 , I10.10.1
Copyright
Copyright © Materials Research Society 2002

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