Optical Constant and Electrical Resistivity of Annealed Sn3Sb2S6 Thin Films

Abstract

In this study, we report the annealing effects on the physical properties of Sn3Sb2S6 thin films. Sn3Sb2S6 thin films were prepared onto non-heated glass substrates via thermal evaporation technique. The as-deposited films were annealed in air for 1 h in the temperature range from 100 to 300 °C. X-ray diffraction results show that the crystallinity of the thin films increased after annealing. The microstructure parameters crystallite size, dislocation density, lattice strain and stacking fault probability were calculated. The optical properties were obtained from the analysis of the experimental recorded transmittance and reflectance spectral data over the wavelength range 300–1800 nm. High absorption coefficient (105 cm−1) reached to the visible and near-IR spectral range. A decrease in optical band gap from 1.92 to 1.71 eV by increasing the air annealing temperature was observed. Oscillator energy E o and dispersion energy E d of the films after annealing were estimated according to the model of Wemple–DiDomenico single oscillator. Spitzer–Fan model was applied to determine the electron free carrier susceptibility and the ratio of carrier concentration to the effective mass. The layers annealed at temperatures >150 °C undergo abrupt changes in their electrical properties and exhibit a resistive hysteresis behavior. These properties confer to the material interest perspectives for its application in diverse advanced technologies such as photovoltaic applications and optical storage.