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Band Offsets and Anomalous Deep Defect Distribution at the Hydrogenated Amorphous Silicon-Crystalline Silicon Interface via Junction Capacitance Techniques

Published online by Cambridge University Press:  25 February 2011

J. M. Essick  and
J. D. Cohen
J. M. Essick
Affiliation:
Department of Physics, University of Oregon, Eugene, OR 97403
J. D. Cohen
Affiliation:
Department of Physics, University of Oregon, Eugene, OR 97403
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Abstract

A novel a-Si:H/c-Si Schottky diode heterostructure device premits the study of the capacitive response to relatively low temperatures (25 K) and also allows fast pulse filling capture measurements of electrons from the c-Si substrate into a-Si:H defect states. These latter measurements, as well as capacitance vs. temperature measurements on these diodes, indicate a nearly zero conduction band offset (50±50 meV). We also have observed trapping of holes at the a-Si:H/c-Si valence band discontinuity ΔEv. A clear threshold for the subsequent optical release of these trapped holes by sub-bandgap light yields a value of ΔEv = 0.58±0.02 eV. Finally, photocapacitance spectra along with thermally stimulated capacitance (TSCAP) measurements indicate an anomalously large (l×1018/cm3) Gaussian-shaped defect band located a Ec - 0.88 eV with a FWHM of 0.46 eV. Model calculations of the high temperature capacitance-voltage dependence indicate these defects lie predominately within 350 Å of the a-Si:H/c-Si interface.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 149: Symposium E – Amorphous Silicon Technology - 1989 , 1989 , 699
Copyright
Copyright © Materials Research Society 1989

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References

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