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Advances in Condensed Matter Physics
Volume 2011 (2011), Article ID 910967, 6 pages
http://dx.doi.org/10.1155/2011/910967
Research Article

The Role of Dopant Concentration on Conductivity and Mobility of CdTe Thin Films

1Applied Physics Department, Sciences College, University of Sharjah, P.O. Box 27272, Sharjah, UAE
2Physics Department, Education College, Al-Mustansirya University, Baghdad, Iraq
3Physics Department, Science College, University of Baghdad, P.O. Box 47162, Jadiriyah, Baghdad, Iraq

Received 16 August 2010; Revised 9 April 2011; Accepted 27 April 2011

Academic Editor: Jörg Fink

Copyright © 2011 Ala 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

Films of CdTe pure and doped with various atomic percentages of Al and Sb (0.5, 1.5 & 2.5) were prepared, and their electrical properties were investigated. The films were prepared by thermal evaporation on glass substrates at two substrate temperatures ( 𝑇 𝑠 = R T & 423 K). The results showed that the conduction phenomena of all the investigated CdTe thin films on glass substrates are caused by two distinct mechanisms. Room temperature DC conductivity increases by a factor of four for undoped CdTe thin films as 𝑇 𝑠 increases and by 1-2 orders of magnitude with increasing dopant percentage of Al and Sb. In general, films doped with Sb are more efficient than Al-doped films. The activation energy ( 𝐸 π‘Ž 2 ) decreases with increasing 𝑇 𝑠 and dopant percentage for both Al and Sb. Undoped CdTe films deposited at RT are p-type convert to n-type with increasing 𝑇 𝑠 and upon doping with Al at more than 0.5%. The carrier concentration decreases as 𝑇 𝑠 increases while it increases with increasing dopant percentage. Hall mobility decreases more than three times as Al increases whereas it increases about one order of magnitude with increasing Sb percentage in CdTe thin films deposited at 423 K and RT, respectively.