Low temperature optoelectrical studies on nanocrystalline CdS-ZnO nanocomposite thin films

We report here low temperature photoluminescence (PL) and electrical studies on nanocrystalline CdS-ZnO nanocomposite thin films. These films were deposited on quartz substrate by rf sputtering method (particle size ~2-3 nm). The band edge emission for the nanocrystalline thin films shifts towards blue region with respect to the bulk band edge emission due to quantum confinement effect. Quantum yield at low temperature (10 K) for the nanocrystalline CdS-ZnO nanocomposite thin films shows much higher enhancement than pure nano CdS and ZnO thin films. The intensive emission properties of the composite films have a great potential for use as nanoscaled optoelectronic intensive light emitters under different temperature. Current-Voltage (I-V) study shows that conductivity is also higher for the composite thin films than the pure nano CdS film. Two broad peaks due to surface states has been observed in thermally stimulated current (TSC) spectrum for nanocrystalline ZnO thin film.