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Photoconductivity studies of discrete defect levels in amorphous chalcogenides

M. L. BENKHEDIR1, J. WILLEKENS1, N. QAMHIEH2, E. V. EMELIANOVA1, M. BRINZA1, G. J. ADRIAENSSENS1,*

Affiliation

  1. University of Leuven, Halfgeleiderfysica, Celestijnenlaan 200D, B-3001 Leuven, Belgium
  2. Department of Physics, UAE University, PO Box 17551, Al Ain, United Arab Emirates

Abstract

The disordered nature of the amorphous semiconductors results in the presence of a significant density of localised electronic states in the energy gap between their valence and conduction bands. In the chalcogenide materials this leads to band edges being widened into tails of localised states with densities well above 1016 cm−3eV−1 as far as 0.5 to 0.7 eV into the gap. Discrete defect levels, caused by specific co-ordination defects, often have a lower density and remain, consequently, frequently undetected by optical spectroscopies. Through the use of photoconductivity techniques, where transport and recombination processes follow the initial optical absorption, it becomes possible to locate some of those discrete defect levels..

Keywords

Chalcogenide semiconductors, Defect levels, Photoconductivity, Localized states.

Submitted at: Nov. 1, 2006
Accepted at: Jan. 15, 2007

Citation

M. L. BENKHEDIR, J. WILLEKENS, N. QAMHIEH, E. V. EMELIANOVA, M. BRINZA, G. J. ADRIAENSSENS, Photoconductivity studies of discrete defect levels in amorphous chalcogenides, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 1, pp. 43-49 (2007)