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Defect Formation Mechanism During PECVD of a-Si:H

Published online by Cambridge University Press:  15 February 2011

Keiji Maeda
Affiliation:
Science University of Tokyo, Department of Materials Science and Technology, Noda, Chiba 278, Japan
Ikurou Umezu
Affiliation:
Science University of Tokyo, Department of Materials Science and Technology, Noda, Chiba 278, Japan
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Abstract

Defect formation mechanism in a-Si:H during PECVD at substrate temperature below 250°C is considered to be breaking of weak bonds in the Urbach tail. To break weak bonds, an extra energy is necessary. This energy is supplied by the reaction energy of SiH3 precursor at the growing surface incorporating SiH2 into the network. The defect density is experimentally shown to be proportional to a product of the energy supply frequency, i.e., SiH2 density, and the weak bond density which is obtained by the Urbach energy. By analysis using the configurational coordinate diagram the energy level of the broken weak bond is determined to be 0.2 eV above the valence band mobility edge. There is similarity of the defect formation mechanism during deposition to that of the Staebler-Wronski effect.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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