The Preparation And Characteristics Of Tin Sulphide (Sn_xS_y) Nano-Films

Tin sulfide(Sn_xS_y) films were prepared by vacuum thermal evaporation on glass substrates to obtain the nano-films by heat-treatment in air and nitrogen(N₂). Then, the characteristics of films were tested by XRD,SEM,EDC,ultraviolet-visible spectrophotometer, and the influences of the proportion of tin and sulfur, process conditions, heat treatment temperature and time on crystalline structure, crystalline grain dimension, surface topography, optical and electrical characteristics of tin sulfide(Sn_xS_y) films were analyed in detail.The experimental results showed that the mixture of Sn and S powder (Sn:S=1:0.8) as evaporation source to prepare thin films then heat treatment (T=330℃, t=40min, N₂) can obtain the SnS nano-films with good performance (021) plane. The SnS films exhibit p-type conductivity and their structure was orthorhombic. The average crystal grains sizes was about 62.17nm., The Sn₂S₃ nano-films can be obtained with orthorhombic structure by heat treatment (T=430℃, t=40min, N₂), when ratios of Sn and S the in mixture powder was 1 to 1.2. Their type of conductivity was n-type. The crystal grains size was about 60.37nm., The SnS₂ nano-films can be obtained with hexagonal structure by heat treatment (T=430℃, t=40min, N₂), when the proportion of Sn and S in mixture powder was 1 to 1.5. Their type of conductivity was n-type. The average the crystal grains was about 77.07nm. The SEM spectrum showed the particles were uniform on surface of three structure films. There was a few of holes on surface, and the gather phenomenon of particles was not obvious. In addition, the EDC spectrum also showed that the components of SnS and SnS₂ thin films approached their stoichiometry, but the stoichiometry of Sn₂S₃ thin film diverged.The transmissivity of SnS thin films was very low by ultraviolet-visible spectrophotometer test (350-900nm), so their absorptivity was very high due to their low reflectivity, the direct band of SnS thin films was about 1.5eV; the transmissivity of SnS₂ thin fims exhibited selectivity, and their direct band was about 2.02eV. The transmissivity of Sn₂S₃ thin films was very low between 350nm to 550nm wavelengh, and the direct band was about 2.0eV.