Pressure-dependent photoluminescence study of ZnO nanowires

The pressure dependence of the photoluminescence (PL) transition associated with the fundamental bandgap of ZnO nanowires has been studied at pressures up to 15 GPa. The near-bandedge luminescence emission is found to shift toward higher energy with applied pressure at a rate of 29.2 meV/GPa with a small second-order term of -0.38 meVGPa2. An effective hydrostatic deformation potential -3.92±0.15 eV for the direct bandgap of the ZnO nanowires is derived from the results. The broad green emission band in ZnO depends on pressure with a linear slope of 15.9 meV/GPa and a quadratic coefficient of -0.71 meVGPa2. The results indicate that the initial states involved in the emission process are deep localized states. © 2005 American Institute of Physics.