Thermal-desorption induced enhancement and patterning of ultraviolet emission in chemically grown ZnO

A significant enhancement of ultraviolet (UV) emission has been observed in chemically grown ZnO samples using a thermal treatment at 200 degrees C. The intensity of UV emission can reach up to fifty times its initial value, while that of the visible emission decreases to a negligible value. Based on the thermal desorption spectroscopy results, the origin of this effect was attributed to the reduction of non-irradiative centres and hydrogen passivation through desorption of adsorbed water and hydroxyl groups. By precisely controlling the local desorption in ZnO with an electron beam, we have not only created optical nanotags on individual ZnO nanorods, but have also written sub-micrometre UV-emission patterns on ZnO films. It is believed that this patterning technique will extend the applications of ZnO to many other fields, such as high-density optical data storage and high-resolution UV-emission displays.