Fabrication and bandgap engineering of doped ZnO microspheres by simple laser ablation in air

Abstract

We synthesized magnesium (Mg)-doped ZnO microspheres by laser ablation of a ZnO sintered target containing magnesium oxide (MgO) with the fundamental of a Nd:YAG laser at 1064 nm. The well-spherical ZnO microcrystals with diameters of 1-20 μm were collected on a substrate which was put near the ablation spot. X-ray diffraction and micro-Raman spectrum indicate that the ZnO microspheres have a crystalline structure. Room-temperature photoluminescence properties of the microsphere were investigated under third harmonic generation of a Nd:YAG laser excitation at 355 nm. An ultraviolet (UV) lasing in whispering gallery mode (WGM) and blue-shift of the UV WGM peaks were observed from the Mg-doped ZnO microsphere.