Doping And Different Substrate Impact The Characteristics Of Sn₂S₃Films

Single source vacuum co-evaporation was utilized to prepare Zn-doped polycrystalline films. The heat-treatment process can improve the properties of the films in nitrogen. The influence of the different proportion/of Zn-doped and substrates on the structure, surface morphology, chemical composition,electrical and optical properties of the Sn2S3film were studied.By using XRD diffraction analysis, the experimental results showed that the films of Sn:S=1:0.4(wt%) and heat treatment at380°C for55minutes presented a good crystallization. The films were a simple orthorhombic Sn2S3polycrystalline, of which the space group were pnam(62). The simple orthorhombic Zn-doped Sn2S3polycrystalline were obtained respectively on the glass and single crystal silicon substrate under condition of the same ratio of Sn and S at9wt%Zn-doped and the heat treatment at370℃for15min in nitrogen. The average crystal size of films were35.69nm (undoped, glass),58.80nm (Zn-doped, glass),59.59nm (Zn-doped, monocrystalline silicon) respectively by using XieLe formula. Average crystal size increased after doping Zn. Atomic force microscope (AFM) and scanning electron microscopy (SEM) displayed an uniform particle size on the surface of films. Energy spectrum analysis (EDS) analysis showed that the stoichiometric ratio Sn:S was changed from1:0.81to1:0.41after doping Zn, S in un-doped Sn2S3thin film suffered serious losses. Results of manual outline meter test showed that the thickness of the films of pure Sn2S3and Sn2S3:Zn (9wt%) were for265nm and346nm respectively. I was found the average value of roughness increased from41nm to50nm.The electrical properties of the films can be improved by Zn-doped and growth of thin films on the silicon substrate.The conduction type of all Sn2S3thin films was N type. Resistance rate of the films on the glass substrate reduced from5.45×102Ω·cm to6.05 ×101Ω·cm after Zn-doped. Resistance rate of the films on the silicon substrate was1.54Ω·cm.Direct optical band gap of prepared Sn2S3films was1.85eV. After Zn-doped(9wt%), the band gap narrowed to1.41eV. Zn doping enhanced the infrared light absorption of the films.The absorption coefficient was about105cm-1.