Structural and optical properties of ZnO films on Si substrates using a γ-Al₂O₃buffer layer

High quality ZnO films have been successfully grown on a Si (100) substrate by metal organic chemical vapour deposition with a γ-Al 2 O 3 buffer. The crystal structure, surface morphology and optical properties of the ZnO films were characterized by x-ray diffraction, Raman spectroscopy, atomic force microscopy and photoluminescence (PL) spectroscopy. The properties of the films with the Al 2 O 3 buffer were improved in comparison with those of as-grown ZnO films. It is shown that the ZnO films with the γ-Al 2 O 3 buffer grown on Si (100) substrates have a highly-preferential c -axis (0002) orientation, a narrow (0002) peak, smooth surface morphology and better PL spectral properties. This demonstrates that the use of γ-Al 2 O 3 /Si as a ZnO substrate is beneficial for reducing the residual stress for further growth of ZnO films, compared with the growth on bulk Si substrates.