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Electronic Properties of Sputtered a-Si1−x, Snx:H Alloys and Comparison with Electronic Structure Calculations

Published online by Cambridge University Press:  26 February 2011

D. Girginoudi
Affiliation:
Laboratory of Electrotechnical and Electronic Materials Technology, Department of Electrical Engineering, Democritus University of Thrace, 67100 Xanthi, Greece
N. Georgoulas
Affiliation:
Laboratory of Electrotechnical and Electronic Materials Technology, Department of Electrical Engineering, Democritus University of Thrace, 67100 Xanthi, Greece
A. Thanailakis
Affiliation:
Laboratory of Electrotechnical and Electronic Materials Technology, Department of Electrical Engineering, Democritus University of Thrace, 67100 Xanthi, Greece
A. D. Zdetsis
Affiliation:
Research Center of Crete and Physics Department, University of Crete, Iraldio, Crete, Greece
G. Kiriakidis
Affiliation:
Research Center of Crete and Physics Department, University of Crete, Iraldio, Crete, Greece
A. Christou
Affiliation:
Naval Research Laboratory, 4555 Overlook Avenue, S.W., Washington, DC 20375-5000
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Abstract

Amorphous hydrogenated silicon-tin alloys have been prepared by if sputtering using a target of silicon with stripes of tin placed over the silicon surface in order to attain the appropriate silicon-tin composition. It is shown that for the composition range investigated, 0 ≤ 5 x ≤ 0.51, the addition of Sn moves the conduction band edge, thereby closing the optical band gap. The dependence of Eg on x can not be described by a single linear relationship. Sn also creates dangling bonds which further increase the material disorder. The electrical dc dark conductivity increases less than expected with increasing Sn content based on a simple decrease in band gap. This and the temperature dependence of the dark conductivity suggest a transition from extented state free-carrier conduction to localized state hopping conduction. The bonding between Si and H competes with that of Sn and H. Photoluminescence measurements show the presence of defect state radiative recombination. Calculations of optical band gaps, using the Coherent Potential Approximation with diagonal disorder and the off-diagonal disorder being treated within the virtual crystal approximation, are in excellent agreement with the experimental results.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

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