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Compositional variation and thermal annealing effect on optical properties of Se-Te-Sb semiconductor thin films

E. R. SHAABAN1,* , H. A. ELSHAIKH2, M. M. SORAYA2

Affiliation

  1. Physics Department, Faculty of Science, Aswan University, Aswan, Egypt
  2. Physics Department, Faculty of Science, Al-Azhar University, Assuit, 71542, Egypt

Abstract

Thin films with thickness of about 1040 nm of the semiconducting glassesSe80-xTe20Sbx with x = 0, 2, 4, 6, 8, and 10 at. % prepared by melt quench technique was evaporated by thermal evaporation onto glass substrates. The optical constant (refractive index, extinction coefficient, and absorption coefficient) of different composition, and annealed films have been studied as a function of photon energy in the wavelength range 400 - 2500 nm. Analysis of the optical absorption data shows that the rule of non-direct transitions predominates for as prepared Se-Te-Sb, and allowed direct transition for annealed sample. It has been found that the refractive index increase with increasing Sb content in Se80-xTe20Sbx, and decrease with annealing temperature for Se76Te20Sb4 in crystallization region of DSC curve. In terms of Wemple-DiDomenico model, the dispersion of the refractive index is discussed. The results refer to increase the refractive index with increasing Sb contents over the entire spectral range, which is related to the increased polarizability of the larger Sb atoms (atomic radius, 1.53 A◦), in comparison with Se atoms (atomic radius, 1.22 A◦), while the energy gap decreases with increasing Sb contents, which was discussed in terms of the chemical bond approaches..

Keywords

Amorphous semiconductors, Thin films, Optical constants, Energy gap, Cohesive energy, Thermal annealing.

Citation

E. R. SHAABAN, H. A. ELSHAIKH, M. M. SORAYA, Compositional variation and thermal annealing effect on optical properties of Se-Te-Sb semiconductor thin films, Optoelectronics and Advanced Materials - Rapid Communications, 9, 5-6, May-June 2015, pp.587-600 (2015).

Submitted at: Nov. 3, 2013

Accepted at: May 7, 2015