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Steady-state photoconductivity in amorphous Ge2Sb2Te5 films

N. QAMHIEH1,* , S. T. MAHMOUD1, H. GHAMLOUCHE1, M. L. BENKHEDIR2

Affiliation

  1. Department of Physics, PO Box 17551, UAE University, Al Ain, United Arab Emirates
  2. Laboratoire de physique appliquée et théorique, centre universitaire de Tébessa, Tébessa 12000 Algeria

Abstract

Steady-state photoconductivity measurements are carried out on thermally evaporated thin films of amorphous Ge2Sb2Te5 samples in the temperature range between 323 and 243 K. The temperature dependence of the photoconductivity ensures the absence of the maximum normally observed in chalcogenides, and the photocurrent is thermally activated with activation energy slightly lower than that of the dark current value, 0.22±0.02 eV. The measured activation energies suggest recombination dominated by a trap states located at the equilibrium Fermi energy level. In the low temperature range another defect level corresponds to a deep electron trap carrier transport can be suggested which leads to low-temperature sensitisation of the photocurrent. The latter is evidenced from the γ values of approximately 1.0 in the Lux-Ampere characteristics..

Keywords

Phase change materials, Density of states, Defects, Photoconductivity, Chalcogenides.

Submitted at: May 5, 2008
Accepted at: June 9, 2008

Citation

N. QAMHIEH, S. T. MAHMOUD, H. GHAMLOUCHE, M. L. BENKHEDIR, Steady-state photoconductivity in amorphous Ge2Sb2Te5 films, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 6, pp. 1448-1451 (2008)