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Electron Collisions in the Plasma as a Major Factor in the Growth of Amorphous Hydrogenated Carbon

Published online by Cambridge University Press:  25 February 2011

S. Lin  and
Bernard J. Feldman
S. Lin
Affiliation:
Department of Physics and Astronomy, Center for Molecular Electronics, University of Missouri - St. Louis, St. Louis, MO 63121
Bernard J. Feldman
Affiliation:
Department of Physics and Astronomy, Center for Molecular Electronics, University of Missouri - St. Louis, St. Louis, MO 63121
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Abstract

We have measured the dependence of the optical bandgap of amorphous hydrogenated carbon as a function of self-bias voltage and external bias voltage. It is observed that there is a much stronger variation in the optical bandgap with self-bias voltage than external bias voltage. We explain this observation in terms of collisions in the plasma between electrons and precursor molecules and ions that break carbon-hydrogen bonds. Increased self-bias voltage causes increased collisions, more broken CH bonds, precursor ions and molecules more deficient in hydrogen, leading to grown films with lower hydrogen concentrations and thus smaller optical bandgaps. This interpretation is further supported by plasma emission spectroscopy where the intensity ratio of CH to H lines decreases with increasing self-bias voltage, demonstrating that increased self-bias voltage does lead to increased electron collisions in the plasma and more broken CH bonds.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 270: Symposium M – Novel Forms of Carbon , 1992 , 463
Copyright
Copyright © Materials Research Society 1992

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References

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