Journal article
Optical study of thin (As2Se3)1-x(Agl)x films



Publication Details
Authors:
Popov, C.; Fuhrmann-Lieker, T.
Publication year:
2007
Journal:
Journal of Optoelectronics and Advanced Materials
Pages range:
326
Volume number:
9
ISSN:
1454-4164

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.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.

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