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Comparative structural and optical properties of Ge2Sb2Te5, In0.3Ge2Sb2Te5 and Se2Sb2Te6 thin films

N. QAMHIEH1,* , S. T. MAHMOUD1, H. GHAMLOUCHE1

Affiliation

  1. Department of Physics, UAE University, P. O. Box 17551 Al-Ain, U.A.E

Abstract

Structural and optical properties of thermally evaporated Ge2Sb2Te5, In0.3Ge2Sb2Te5 and Se2Sb2Te6 thin films are reported. The structural analysis is investigated using X-Ray diffraction measurements from which the lattice constants are calculated and found to be greater for Se2Sb2Te6 films than for Ge2Sb2Te5. The refractive indices are deduced from optical transmission measurements whereas the optical band gap (Eg) is obtained from optical absorption measurements. It is found that Se2Sb2Te6 film has higher optical band gap and lower refractive index than Ge2Sb2Te5 film. This could be attributed to the presence of selenium that has a wider energy gap than Ge. The addition of indium to Ge2Sb2Te5 alloy leads to a slight increase in the refractive index and the optical gap, but no significant change on the lattice constant is observed..

Keywords

Ge-Sb-Te, In-Ge-Sb-Te, Se-Sb-Te, Optical Properties, Lattice Constant, Chalcogenides, Phase-Change.

Submitted at: July 5, 2009
Accepted at: Dec. 10, 2009

Citation

N. QAMHIEH, S. T. MAHMOUD, H. GHAMLOUCHE, Comparative structural and optical properties of Ge2Sb2Te5, In0.3Ge2Sb2Te5 and Se2Sb2Te6 thin films, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 12, pp. 1995-1999 (2009)