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Advances in Condensed Matter Physics
Volume 2010, Article ID 428739, 8 pages
http://dx.doi.org/10.1155/2010/428739
Research Article

Electrical and Optical Properties of G e 𝑥 S i 𝟏 − 𝑥 :H Thin Films Prepared by Thermal Evaporation Method

1Applied Physics Department, College of Sciences, University of Sharjah, P.O. Box 27272 Sharjah, UAE
2Physics Department, College of Sciences, University of Baghdad, P.O. Box 47162, Jadiriyah, Baghdad, Iraq

Received 28 May 2009; Accepted 27 January 2010

Academic Editor: Gayanath Fernando

Copyright © 2010 A. A. J. Al-Douri et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Thin a- G e 𝑥 S i 1 − 𝑥 :H films were grown successfully by fabrication of designated ingot followed by evaporation onto glass slides. A range of growth conditions, Ge contents, dopant concentration (Al and As), and substrate temperature, were employed. Stoichiometry of the thin films composition was confirmed using standard surface techniques. The structure of all films was amorphous. Film composition and deposition parameters were investigated for their bearing on film electrical and optical properties. More than one transport mechanism is indicated. It was observed that increasing substrate temperature, Ge contents, and dopant concentration lead to a decrease in the optical energy gap of those films. The role of the deposition conditions on values of the optical constants was determined. Accordingly, models of the density of states for the G e 0 . 5 S i 0 . 5 :H thin films as pure, doped with 3.5% of Al (p-type) and that doped with 3.5% As (n-type), were proposed.