Substrate Temperature-Dependent Physical Properties of Thermally Evaporated Sn4Sb6S13 Thin Films

摘要

In this work,the homogenous thin films of sulfosalt Sn_4Sb_6S_(13) were successfully synthesized by the thermal evaporation technique onto corning 7059 glass substrates heated at various temperatures in the range of 30-200 ℃.The surface morphology and structural characteristics of Sn_4Sb_6S_(13) films were analyzed by atomic force microscopy,X-ray diffraction,and energy-dispersive X-ray,respectively.The X-ray diffraction analysis revealed that Sn_4Sb_6S_(13) thin films crystallized in monoclinic structure according to a preferential direction(6 11).An improvement in the structural properties by increasing the substrate temperature was observed.The values of some important parameters such as absorption coefficient(α),band gap(E_g),refractive index(n),extinction coefficient(k),and dielectric constant(ε_∞) of thin film were determined.The absorption coefficient was larger than 10~5 cm^(-1) in the visible range.The electron transition of Sn_4Sb_6S_(13)films was direct allowed with the values that decreased(2-1.69 eV) by increasing substrate temperature from 30 to 200 ℃.The dispersion data obeyed the single oscillator relation of the Wemple-DiDomenico model and Cauchy model.The electrical free carrier susceptibility and the carrier concentration of the effective mass ratio were estimated according to the model of Spitzer and Fan.