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On the compositional dependence of refractive index in amorphous GexAsxSe1-2x films

M. S. IOVU1,* , V. G. BENEA1, E. P. COLOMEICO1, M. A. IOVU1, I. A. COJOCARU1, O. I. SHPOTYUK1, R. YA. GOLOVCHAK2

Affiliation

  1. Institute of Applied Physics, Str. Academiei 5, MD-2028, Chisinau, R. Moldova
  2. Scientific Research Company “Carat”, Str. Stryjska 202, Lviv, Ukraine

Abstract

Some optical properties of amorphous GexAsxSe2-x thin films prepared by thermal “flash” evaporation on the glass substrates at Tsubstr=100 oC are presented. From transmission spectra T(λ), have been calculated the absorption coefficient α(hν), the values of optical band gap Eg and dispersion curves of refractive index n(λ). It was established that annealing of thin films at high temperatures decreased the absorption coefficient α and refractive index n. The values of optical band gap Eg, determined from the Tauc plot (α⋅hν)1/2 vs. (hν), increased with annealing temperature Tan. Thus, for As0.09Ge0.09Se0.82 composition, the variation of optical band gap versus annealing temperature is ΔEg/ΔTan=1.275⋅10-4 eV/oC. These features may be used in developing of new functional media based on GexAsxSe1-2x films for modern optoelectronics..

Keywords

Chalcogenide glass, Amorphous films, Optical absorption, Refractive index, Photodarkening effect.

Submitted at: May 5, 2011
Accepted at: Nov. 23, 2011

Citation

M. S. IOVU, V. G. BENEA, E. P. COLOMEICO, M. A. IOVU, I. A. COJOCARU, O. I. SHPOTYUK, R. YA. GOLOVCHAK, On the compositional dependence of refractive index in amorphous GexAsxSe1-2x films, Journal of Optoelectronics and Advanced Materials Vol. 13, Iss. 11-12, pp. 1417-1422 (2011)