Structural and optical properties of Ni~(2+)-doped ZnO thin films and powder

Ni2+-doped ZnO(0.8at%) thin films that show the single-phase wurtzite(hexagonal) structure were grown on single-crystalline silicon(100) substrates by means of pulsed laser deposition using an XeCl excimer laser under vacuum and a 5 Pa oxygen atmosphere.Under the oxygen atmosphere,thin film grows along the direction of(002) and has a smooth surface;the average particle size of thin film is 80 nm.The thin films prepared under vacuum atmosphere appear impurity phase that is Zn2SiO4,and the average particle size of thin film is 150 nm.Compared with the thin film prepared under vacuum atmosphere,the thin film prepared under the oxygen atmosphere has more obvious intrinsic emission peak and shows the blue-violet emission located at 425 nm which is ascribed to an electronic transition between the donor level of interstitial Zn and the valence band.And it shows a strong blue emission peak at 482 nm,which is attributed to the transition between the vacancy of oxygen and interstitial oxygen.Meanwhile the intensity of the blue emission peak at 449 nm from oxygen defects greatly reduces.