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Persistent photoconductivity in AlGaN films Grown by mocvd

Published online by Cambridge University Press:  10 February 2011

A. Y. Polyakov ,
N. B. Smirnov ,
A. V. Govorkov  and
J. M. Redwing
A. Y. Polyakov
Affiliation:
Institute of Rare Metals, Moscow 109017, B. Tolmachevsky 5, Russia, [email protected]
N. B. Smirnov
Affiliation:
Institute of Rare Metals, Moscow 109017, B. Tolmachevsky 5, Russia, [email protected]
A. V. Govorkov
Affiliation:
Institute of Rare Metals, Moscow 109017, B. Tolmachevsky 5, Russia, [email protected]
J. M. Redwing
Affiliation:
Epitronics/ ATMI, 21002 North 19th Ave., Suite 5, Phoenix, AZ 85027, USA
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Abstract

Photocurrent transients due to illumination by above-bandgap and subbandgap light were studied for Si doped and undoped films of AlGaN grown by MOCVD on sapphire and having compositions ranging from 0% to 60% of Al. It is shown that in Si doped layers the decay of photoconductivity takes extremely long time (hundreds and thousands seconds, depending on temperature, composition and illumination conditions). Both the kinetics of rise and fall of photoconductivity are best described by stretched exponents. The characteristic decay times are virtually temperature independent for temperatures below 270–290K and have activation energy of 0.14–0.26 eV (depending on composition) for higher temperatures. The decay times become longer with decreased light intensity and increase when above-bandgap light excitation is replaced by subbandgap light excitation (the photocurrent values from which the decay starts being equivalent). The results cannot be quantitatively explained by the effects of changing of the quasi-Fermi level position well known for DX-centers in AlGaAs. No persistent photoconductivity could be observed in high resistivity undoped AlGaN films with 5%, 15% and 25% of Al.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 512: Symposium F – Wide Bandgap Semiconductors for High Power, High Frequency , 1998 , 537
Copyright
Copyright © Materials Research Society 1998

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References

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