Preparation and photocatalytic activity of MgxZn1−xO thin films on silicon substrate through sol-gel process

Abstract Magnesium doped zinc oxide (Mg x Zn 1− x O) thin films were synthesized on silicon substrate through sol–gel process. Mg 0.15 Zn 0.85 O thin films were annealed at 500–800 °C and ZnO, Mg 0.1 Zn 0.9 O, Mg 0.05 Zn 0.95 O thin films were annealed at 600 °C for 60 min, respectively. The results show that all the samples are of a hexagonal wurtzite structure of ZnO. The surface morphology is strongly dependent on mean grain size and surface fluctuation. Fourier transform infrared spectra reveal that the vibration peak at 420 cm −1 is of the intrinsic lattice absorption of ZnO. The peak at 1083 cm −1 belongs to Si O Si asymmetric stretching vibration. Photoluminescence spectra show that the ultraviolet emission (365–400 nm) and the broad visible emission (469–569 nm) are observed. In particular, Mg 0.05 Zn 0.95 O thin film annealed at 600 °C exhibits the highest photocatalytic activity, degrading MO by almost 85.8% after 180 min illumination. The photocatalytic activity of the thin film is a synergistic effect defined by grain size, roughness factor, oxygen defects and amorphous MgO.