Preparation, Microstructures And Photoelectric Properties Of Thin Films Of Sb Doped Sn₂S₃

The thin films of Sb-doped Sn₂S₃ are grown on glass substrates by thermal evaporation. The orthorhombic polycrystalline Sn₂S₃ films with good properties are treated under different heat conditions in nitrogen. The structures and optical properties of the thin films influenced by different percent of Sb and different heat treatment conditions are investigated.The XRD analysis gives the result that the thin films with proportion of tin and sulfur being 1:1.2(at %) treated for 40 minutes by N₂ at 380℃, 400℃and 430℃can form orthorhombic Sn₂S₃ thin films. The best heat treatment condition is 380℃, 40min and the average size of the grains is 76.71 nm.The time of heat treatment decreases by doping Sb at the same temperature. The 5%Sb doped thin films treated for 30 minutes by N₂ at 380℃can form polycrystalline Sn₂S₃ films and the average size of grains is 56.91 nm.The SEM spectrum shows that the surface of the deposited films have uniform size particles and tight phenomenon of gathering of particles. The EDC spectrum shows that the component of Sn₂S₃ thin film approaches their stoichiometry being 1:1.49, but the stoichiometry of 5% Sb doped Sn₂S₃ thin film being 1:0.543 diverges.The XPS spectrum shows that the surface component proportion of tin and sulfur being 1:1.4 of Sn₂S₃ thin film approaches their stoichiometry, but the stoichiometry of tin and sulfur being 1:0.17 of 5% Sb doped Sn₂S₃ thin film diverges obviously. The element of Sn,S and Sb in the films exists as Sn²⁺,Sn⁴⁺,S^2- and Sb⁵⁺ respectively.The transmissivity of Sn₂S₃ thin films is very low between 350nm to 500nm wavelengh, and the direct band gap is between 1.9-2.3eV.The films of 5%Sb doped nearly absorb all light between 350nm to 900nm wavelengh and the direct band gap of 5% Sb doped Sn₂S₃ thin films is about 1.56eV.All the deposited films exhibit the n-type. The resistance of Sn₂S₃ thin films without doping Sb is 10⁵Ω. while the resistance of 5% Sb doped Sn₂S₃ thin films is about 10²Î©, so the electric property of Sn₂S₃ thin film can be optimized by doping Sb aptly.