Physical properties of Sn4Sb6S13 thin films prepared by a glancing angle deposition method

Abstract

Sn4Sb6S13 thin films were prepared by thermal evaporation method using Glancing Angle Deposition (GLAD) technique. The incident angle γ between the particle flux and the normal to the substrate was varied from 0° to 85°. XRD technique and optical measurement are used to study the crystalline structure and optical properties of these films. The X-ray diffraction analysis indicated that the thin films deposited at low incident angle had a monoclinic structure with a preferred orientation along the (6¯11) plane. However the layers became amorphous at γ=60° and above. The absorption coefficients and the band gap values of the films were calculated by optical transmission and reflection measurements. It was observed that the optical band-gap values increase from 1.6eV to 2eV with increasing the flux incident angle. The prepared thin films have relatively high absorption coefficients between 104 and 105cm−1 in the visible and the NIR spectral ranges. The refractive index and porosity exhibit an opposite evolution as the incident angle γ rises. At γ=60° the layers show a maximum of birefringence (Δn) of 0.062 and a packing density of 0.620. The properties reported here facilitate the use of Sn4Sb6S13 thin films as a potential candidate in many applications such as retardation plate and polarizer.