Vacuum annealing effects on the structural and optical properties of SnSb2S4 thin films fabricated by thermal evaporation technique

SnSb2S4 thin films have been deposited by thermal evaporation technique on non-heated glass substrates and subsequently annealed at 473 and 673 K. The influence of annealing temperature on the structural, morphological, optical and electrical properties was analyzed by X-ray diffraction, atomic force microscopy (AFM), spectrophotometer and hot probe method, respectively. The as-deposited and annealed films were polycrystalline in nature with preferential growth along (6 2 1) plane. The SnSb2S4 films annealed at 673 K exhibited an optical transmittance of 30% and a direct band gap of 1.4 eV. The dispersion behavior of the refractive index was studied in terms of the single-oscillator Wemple–DiDomenico and Cauchy models, and the optical parameters such as refractive index, extinction coefficient, oscillator energy, dispersion energy and Cauchy's constants were found. The electrical free carrier susceptibility and the carrier concentration on the effective masse ratio were estimated according to the model of Spitzer and fan.