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Defect States and Structural Disorder in a-Si.

Published online by Cambridge University Press:  21 February 2011

B. N. Davidson ,
G. Lucovsky  and
J. Bernholc
B. N. Davidson
Affiliation:
Departments of Physics and Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695–8202
G. Lucovsky
Affiliation:
Departments of Physics and Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695–8202
J. Bernholc
Affiliation:
Departments of Physics and Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695–8202
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Abstract

We have examined the distribution of the neutral dangling bond defect states, T30, as a function of the local disorder. T30 defects in a-Si play an important role in many of the current models of the metastable photoconductivity. To understand the relationship between the T30 defect and its bonding environment, the Local Density of States (LDOS) for under-coordinated Si atoms in disordered environments are calculated using the cluster-Bethe lattice method, CBLM. Our Hamiltonian employs the tight-binding parameters of an sp3 orbital basis containing both 1st and 2nd nearest-neighbor interaction terms fit to c-Si band structure. Averaged LDOS of atoms with various bond angle distortions are calculated in order to demonstrate the relationship between the standard deviation in bond angle and the width of the defect states. The CBLM is also used to determine the extent of the valence band tails as a function of the standard deviation in bond angle. In addition, the LDOS of clusters with 2 dangling bonds are examined to determine the degree that their energy levels split due to their interaction with each other.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 258: Symposium A – Amorphous Silicon Technology – 1992 , 1992 , 263
Copyright
Copyright © Materials Research Society 1992

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References

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