Structural and optical properties of MgxZn1−xO thin films deposited by magnetron sputtering

MgxZn1−xO films (0⩽x⩽0.30) have been prepared on sapphire substrates by radio frequency magnetron sputtering at 80 °C. Structure, morphology and optical properties of the MgxZn1−xO films were studied using X-ray diffraction meter, atomic force microscopy and transmittance spectra, respectively. The thin films had hexagonal wurtzite single-phase structure of ZnO and a preferred orientation with the c-axis perpendicular to the substrates. By increasing Mg content in the films up to x=0.30, the c-axis lattice constant of the MgxZn1−xO film decreased 1.9%. Transmittances of MgxZn1−xO were nearly equivalent to those of ZnO. The optical band gaps of MgxZn1−xO films were determined by the transmittance spectra, which increased from 3.24 eV at x=0 to 3.90 eV at x=0.30.