Excitonic photoluminescence and photoresponse of ZnS nanowires

Single crystal ZnS nanowires are fabricated by vapor phase transport method on sapphire substrate in the presence of Au catalyst. The morphology, composition, and crystal structure are characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM). XRD and HRTEM reveal that the ZnS nanowires have perfect single crystal wurtzite structure. The temperature-dependent photoluminescence spectra show that the ZnS nano wires present pure near-bandgap ultraviolet exciton recombination emission at 347 nm. The exciton-related optical properties, including exciton activation energy, temperature -dependent exciton energy and Varshni coefficients describing exciton energy variation, are systematically discussed. In addition, an individual ZnS nanowire-based ultraviolet photodetector is fabricated, which shows good photoresponse ability and fast response rate. The result shows that the ZnS nanowires are particularly suitable for UV photodetectors. (C) 2016 Elsevier B.V. All rights reserved.