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Defect Formation During Deposition of Undoped a-Si:H BY PE-CVD

Published online by Cambridge University Press:  10 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

Dependence of the as-grown defect concentration in PECVD undoped a-Si:H on the deposition parameters, i.e., substrate temperature and precursor density in the plasma produced by H2 dilution of SiH4 gas, is investigated. It is found that the defect density behaves similarly to the concentration of SiH2 configuration in the films deposited at substrate temperatures below 300 °C. The defect concentration, however, varies proportionally to about the 3rd to 4th power of the SiH2 concentration depending on the deposition condition. Based on the surface reaction mechanism proposed in our previous paper, a large enthalpy change is expected to accompany the bimolecular reaction of the adsorbed SiH3 radicals, which incorporates the SiH2 configuration into the network. Characteristics of the defect formation caused by tile breaking Si-Si bond near the growing surface owing to this energy is compared with those of the Staebler-Wronski effect. Both similarity in dependence on II atom concentration and difference in annealing temperature are discussed. It is concluded that the as-grown defects are most likely formed during deposition owing to the large enthalpy change accompanying the bimolecular surface reaction.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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