Effects of oxygen partial pressure and substrate temperature on the structure and optical properties of Mg xZn 1− xO thin films prepared by magnetron sputtering

Abstract

Deposited with different oxygen partial pressures and substrate temperatures, Mg x Zn 1− x O thin films were prepared using a Mg 0.6Zn 0.4O ceramic target by magnetron sputtering. The structural and optical properties of the prepared thin films were investigated. The X-ray diffraction spectra reveal that all the films on quartz substrate are grown along (2 0 0) orientation with cubic structure. The lattice constant decreases and the crystallite size increases with the increase of substrate temperature. Both energy dispersive X-ray spectroscopy and calculated results suggest the ratio of Mg/Zn increases with increasing substrate temperature. The thin film deposited with T s = 500 °C has a minimal rms roughness of 7.37 nm. The transmittance of all the films is higher than 85% in the visual region. The optical band gap is not sensitive to the oxygen partial pressure, while it increases from 5.63 eV for T s = 100 °C to 5.95 eV for T s = 700 °C. In addition, the refractive indices calculated from transmission spectra are sensitive to the substrate temperature. The photoluminescence spectra of Mg x Zn 1− x O thin films excited by 330 nm ultraviolet light indicate that the peak intensity of the spectra is influenced by the oxygen partial pressure and substrate temperature.