Effect of Sn Doping on Structural and Electrical Properties of Thermally Evaporated CdSe Thin Films

摘要

Thin films of CdSe and Sn doped CdSe at 1% and 5% dopant level are prepared by thermal evaporation technique using inert gas condensation method. Prepared thin films are characterized by transmission electron microscope (TEM), energy dispersive X-ray analysis (EDX), X-ray diffraction and electrical techniques. TEM analysis reveals the spherical nature of nanoparticles and increase in particle size after doping. The X-ray diffraction study indicates the presence of hexagonal phase of CdSe in undoped as well as in Sn doped CdSe thin films and increase in crystallinity after annealing treatment. A decrease in dark electrical conductivity is observed after doping in as deposited and annealed thin films. Transient photoconductivity measurement has been studied in both as deposited and annealed thin films. Anomalous decay has been found in undoped and Sn doped CdSe thin films at 1% dopant level. The nature of charge carriers is found to change from n-type to p-type after doping in both as deposited and annealed Sn doped CdSe thin films. The charge carrier concentration is calculated using hall coefficient and found to decrease with increase in dopant amount.