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Influence of Sulphur content on the optical properties of glassy SXSe100-X thin films system

M. M. EL NAHASS1,* , M. B. EL DEN2, H. E. A. EL-SAYED1, A. M. A. EL-BARRY1, M. A. M. SEYAM1

Affiliation

  1. Physics Department, Faculty of Education, Ain Shams University, Cairo, Egypt
  2. Physics Department, Faculty of Science, Ain Shams University, Cairo, Egypt

Abstract

Thin films of SxSe100-x, where x = 0 , 2.5 ,5.8 and 7.28 at % S, have been prepared by thermal evaporation technique using quartz and glass substrates kept at room temperature (300 K). EDX analysis of all the SxSe100-x compositions prepared indicate that the compositions are stoichiometric. X-ray diffraction patterns for SxSe100-x compositions, in powder form as well as in thin film forms have an amorphous nature for as deposited films and polycrystalline nature of hexagonal phase after being annealed at 423 K for one hour DAT measurements gave three transition temperatures Tg, Tc and Tm. The optical constants were determined for films of different thickness values (100-500 nm) by using spectrophotometric measurements of the transmittance, T, and the reflectance, R, at normal incidence in the spectral range 400-2500 nm. The obtained values of both n and k were found to be independent of the film thickness.The refractive index, n, attains a peak value at wavelength λc, which is shifted towards the shorter wavelength as the sulphur content is increased. The estimated width of localized states in the forbidden gap and the variation of the indirect and direct optical energy gap as a function of both sulphur content and annealing temperature have been determined. The values of the dispersion energy Ed , the single oscillator energy E0, the infinite dielectric constant ε00 , the lattice dielectric content εL and the ratio N/m*, of the system have been determined and correlated with the type and amount of chemical bonds. The effect of heat treatment on the optical parameters have been also discussed..

Keywords

Optical properties, Thin films, SxSe100-x.

Submitted at: June 11, 2006
Accepted at: Sept. 13, 2006

Citation

M. M. EL NAHASS, M. B. EL DEN, H. E. A. EL-SAYED, A. M. A. EL-BARRY, M. A. M. SEYAM, Influence of Sulphur content on the optical properties of glassy SXSe100-X thin films system, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 5, pp. 1817-1822 (2006)