Dislocations of ZnO single crystals examined by X-ray topography and photoluminescence

Dislocations generated by indentation and subsequent annealing at elevated temperatures up to 800 °C in high quality (0001) wafers of ZnO single crystals were investigated by transmission X-ray topography and photoluminescence. Damages induced by indentation in ZnO wafers were guessed to lead to dislocated regions from X-ray topographic images. PL intensities of 3.36 eV near-band edge peak and 2.4 eV deep emission band in ZnO decreased drastically, with increasing in annealing temperature up to 800 °C, irrespective of dislocated or non-dislocated regions. The development of a new emission band 2.8–3.0 eV was found in non-damaged ZnO through annealing at 700 and 800 °C, which suggests that dislocations suppress the development of the new peak.