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The Limitations of the Constant Photocurrent Method for Determining Subgap Absorption

Published online by Cambridge University Press:  15 February 2011

P. Stradins
Affiliation:
The James Franck Institute, University of Chicago, Chicago Illinois 60637, USA
H. Fritzsche
Affiliation:
The James Franck Institute, University of Chicago, Chicago Illinois 60637, USA
M. Tran
Affiliation:
The James Franck Institute, University of Chicago, Chicago Illinois 60637, USA
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Abstract

The subgap absorption αcpm measured by the constant photocurrent method (CPM) was studied between 4.2K and 300K for different dopings and defect concentrations N in hydrogenated amorphous silicon (a-Si:H). We found that αcpm is reduced by up to a factor 100 between 50K and 200K due to infrared selfquenching which changes the charge state of the defects and enhances recombination. The effect is diminished at high N and large doping. The relative change Δα/α reflects ΔN/N both at very low and high temperatures. For undoped samples αcpm is about four times larger at 4.2K than at 300K. For doped samples the two values are essentially the same.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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References

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