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Optical study of thin (As2Se3)1-x(AgI)x films

T. HINEVA1,* , T. PETKOVA2, C. POPOV3, P. PETKOV1, J. P. REITHMAIER3, T.FUHRMANN-LIEKER4, E. AXENTE5, F. SIMA5, C. N. MIHAILESCU5, G. SOCOL5, I. N. MIHAILESCU5

Affiliation

  1. Laboratory of Thin Films Technology, Department of Physics, University of Chemical Technology and Metallurgy, 8 Kl. Ohridsky blvd, 1756 Sofia, Bulgaria
  2. Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
  3. Institute of Nanostructure Technologies and Analytics, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
  4. Macromolecular Chemistry and Molecular Materials, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
  5. National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, PO-Box MG-36, RO-77125 Bucharest-Magurele, Romania

Abstract

The optical properties of chalcogenide thin films from the pseudo-binary (As2Se3)1-x(AgI)x system, where x=5, 10, 15, 20, 25, 30 and 35 mol.% were studied with respect to the influence of AgI incorporation. Two techniques – vacuum thermal evaporation (VTE) and pulsed laser deposition (PLD) were applied to prepare the films. The films were amorphous, as revealed by X-ray diffraction (XRD); their morphology and topography studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) exhibited uniform homogeneous surfaces. The optical transmission and reflection of the deposited (As2Se3)1-x(AgI)x were investigated in the spectral region 300–3300 nm. The values of the optical parameters (refractive index, n, and extinction coefficient, k) were determined from the spectra. The compositional dependence of the basic optical parameters of the films, specifically their dependence on different AgI contents, was determined. The optical band gap Eg was determined from the Tauc plot αhν=B(Eg – hv)2 and the Eg04 in the strong-absorption region (α ≥104 cm-1) from the relationship α= f (hν). The dispersion of the refractive indices and extinction coefficients and the observed trends in the band gap variation were discussed with respect to the influence of the AgI and film preparation methods..

Keywords

Chalcogenide glasses, Thin films, Optical properties, Band gap structure.

Submitted at: Nov. 1, 2006
Accepted at: Feb. 15, 2007

Citation

T. HINEVA, T. PETKOVA, C. POPOV, P. PETKOV, J. P. REITHMAIER, T.FUHRMANN-LIEKER, E. AXENTE, F. SIMA, C. N. MIHAILESCU, G. SOCOL, I. N. MIHAILESCU, Optical study of thin (As2Se3)1-x(AgI)x films, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 2, pp. 326-329 (2007)