Structural, optical and photoconductivity study of ZnO nanoparticles synthesized by annealing of ZnS nanoparticles

ZnO nanoparticles have been produced by annealing ZnS nanoparticles prepared by solid state reaction method using different temperature of synthesis. The annealing was done at 600 °C for 3 h. The characterization of the samples was done by different techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), UV-vis spectroscopy, FTIR spectroscopy and photoluminescence (PL) spectroscopy. From XRD, the crystal structure is found to convert from cubic ZnS phase to hexagonal ZnO phase. UV-vis spectra show blue-shifting in an absorption edge corresponding to all samples of ZnO nanoparticles as compared to their bulk counterparts. PL spectra of all the samples have an UV emission peak around 388 nm and a broad defect related green emission around 502 nm. In addition to this the samples has been characterized for its photoconducting properties by observing variation of dark current and photocurrent with applied voltage and by recording rise and decay of photocurrent in air.