DC Conductivity and Optical Properties of InSbTe3 Amorphous Thin Films

Abstract

Measurements of dc electrical conductivity and optical properties have been made on InSbTe3 thin films prepared by thermal evaporation having different thickness (25-150) nm range. The structure of InSbTe3 in its powder and thin film forms were investigated by X-ray diffraction (XRD). The electrical conductivity was measured in the temperature (303-392) K range. The obtained values of dc electrical conduction activation energy 2E4 were found to be nearly independent on the film thickness and have the mean value of 0.173 eV in the range considered. The refractive index n and the absorption index k were determined in the spectral range 400-2500 nm. It is observed that n decreases with increasing film thickness at any wave length, while k is practically independent on film thickness in the range 25-150 nm. For films with thicknesses in the range 170-304 nm, the spectral distribution of transmittance T and reflectance R showed that T+R<1 in the whole spectrum which due to light scattering by surface roughness whose existence is confirmed by electron microscopy. Analysis of k indicated that the absorption mechanism refers to the existence of indirect transitions with an optical energy gap of 0.52 eV.