The ultraviolet emission mechanism of ZnO thin film fabricated by sol–gel technology

ZnO thin films were successfully deposited on SiO2/Si substrate by sol–gel technology. The as-grown ZnO thin films were annealed under an ambient atmosphere from 600 to 900 °C by rapid thermal annealing (RTA) process. X-ray diffraction and scanning electron microscopy analyses reveal the physical structures of ZnO thin films. From PL measurement, two ultraviolet (UV) luminescence bands were obtained at 375 and 380 nm, and the intensity became stronger when the annealing temperature was increased. The strongest UV light emission appeared at annealing temperature of 900 °C. The chemical bonding state in ZnO films was investigated by using X-ray photoelectron spectrum. The mechanism of UV emission was also discussed.