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Light-Induced Defects in Medium and Low Gap a-Si,Ge:H,F Alloys

Published online by Cambridge University Press:  26 February 2011

V. Chu
Affiliation:
Department of Electrical Engineering Princeton University, Princeton, New Jersey 08544
J. P. Conde
Affiliation:
Department of Electrical Engineering Princeton University, Princeton, New Jersey 08544
D. S. Shen
Affiliation:
Department of Electrical Engineering Princeton University, Princeton, New Jersey 08544
S. Aljishi
Affiliation:
Department of Electrical Engineering Princeton University, Princeton, New Jersey 08544
S. Wagner
Affiliation:
Department of Electrical Engineering Princeton University, Princeton, New Jersey 08544
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Abstract

A systematic study of the electronic and optical properties of a-Si,Ge:H,F alloys in the initial and light-soaked states is presented. The three alloys have optical gaps of 1.20, 1.34 and 1.40eV. Constant photocurrent method (CPM) spectra show that the higher gap samples begin to exhibit increased subgap absorption due to light soaking much sooner than the low gap sample. Dark arid photoconductivity remain essentially constant as functions of light soaking time up to approximately 100 hours of illumination, when the dark conductivity begins to increase and the photoconductivity begins to decrease simultaneously. The electron mobility-lifetime product measured by the time-of-flight technique shows much scatter but no significant change with light-soaking. The hole mobility-lifetime product on the other hand decreases immediately upon light soaking and continues to decrease gradually with increasing illumination time. A discussion of these effects and a possible explanation in terms of the density of states is presented.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

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