Effects of growth temperature on Mg-doped ZnO films fabricated by pulsed-laser deposition

Magnesium-doped zinc oxide (MZO) films were fabricated by pulsed-laser deposition (PLD) at various substrate temperatures (T-s). The substitution of Mg for Zn sites (Mg-Zn) in the films was confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and room-temperature photoluminescence (RTPL) measurements. Characteristic deep-level emissions (DLE) observed in the RTPL spectra further indicate the presence of Zn vacancies (V-Zn) in the MZO films. Moreover, it was found that the intensity of the blue emission corresponding to V-Zn increases with increasing T-s, indicating the important role played by T-s on the incorporation of Mg into ZnO matrix. Hall effect measurements reveal the p-type conduction of the MZO films grown at 400 degrees C. The p-type characteristic is attributed to the formation of nMg(Zn) - V-Zn complex which could act as acceptor for MZO films.