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Conduction and Valence Band Offsets at the Hydrogenated Amorphous Silicon-Carbon/Crystalline Silicon Interface Via Capacitance Techniques

Published online by Cambridge University Press:  01 January 1993

John M. Essick ,
Richard T. Mather ,
Murray S. Bennett  and
James Newton
John M. Essick
Affiliation:
Department of Physics, Occidental College, Los Angeles, CA 90041
Richard T. Mather
Affiliation:
Department of Physics, Occidental College, Los Angeles, CA 90041
Murray S. Bennett
Affiliation:
Thin Film Division,Solarex Corporation, Newtown ,PA 18940
James Newton
Affiliation:
Thin Film Division,Solarex Corporation, Newtown ,PA 18940
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Abstract

Heterostructure Schottky diode samples each composed of a sub-micron thick layer of intrinsic hydrogenated amorphous silicon-carbon (a-Si1−xCx:H) deposited on an n-type crystalline silicon (c-Si) substrate are used to measure the a-Si1−xCx:H/c-Si band offsets via junction capacitance techniques. The samples range in carbon concentration from x=0.0−0.3. First, a thermally activated capacitance step due to the response of defects at the amorphous/crystalline interface is evident in capacitance vs. temperature spectra taken on all these samples. The bias-dependence of this step’s activation energy provides a direct measure of the a-Si1−xCx:H/c-Si interface potential as a function of c-Si depletion width in each sample. By application of Poisson’s equation, we find that the a-Si1−xCx:H/c-Si conduction band offset ΔEc. increases from 0.00 to 0.10 eV as x increases from 0.00 to 0.26. Second, while under reverse-bias at low temperature, we optically pulsed each sample with c-Si band-gap light to create trapped holes at the a-Si1−xCx:H/c-Si valence band offset ΔEV. By noting the threshold for the subsequent optical release of these trapped holes by sub-band gap light, we found that ΔEV increases from 0.67 to ≥0.83 eV as x increases from 0.00 to 0.26.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 297: Symposium A – Amorphous Silicon Technology - 1993 , 1993 , 705
Copyright
Copyright © Materials Research Society 1993

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References

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