Optical and Excitonic Properties of Crystalline ZnS Nanowires: Toward Efficient Ultraviolet Emission at Room Temperature

A systematic investigation into the excitonic properties of wurtzite ZnS nanowires (NVs) is presented Under optical excitation the ZnS NWs exhibit Strong ultraviolet (UV) emission Optical transition from free exciton A fide exciton-B and shallow level emission are observed and analyzed through power-dependent and temperature dependent photoluminescence spectroscopy measurements performed from 10 to 300 K The excitonic transition and coupling strength of exciton longitudinal optical phonon were directly determined from the evolution of exciton peak energy and peak width broadening Our studies indicate that free excitons in ZnS nanowires are very stable suggesting a great promise for high efficiency light emitting devices and lasers In the UV region Finally, the carrier dynamics of the ZnS NWs were measured and analyzed for the first time by ultrafast spectroscopy