High quality crystalline ZnO buffer layers on sapphire (001) by pulsed laser deposition for III–V nitrides

ZnO thin films with near perfect crystallinity have been grown epitaxially on sapphire (001) by pulsed laser deposition technique. The ω-rocking curve full width at half-maximum of the ZnO(002) peak for the films grown at 750 °C, oxygen pressure 10−5 Torr was 0.17°. The high degree of crystallinity was confirmed by ion channeling technique providing a minimum Rutherford backscattering yield of 2%–3% in the near-surface region (∼2000 Å). The atomic force microscopy revealed smooth hexagonal faceting of the ZnO films. It has been possible to deposit epitaxial AlN films of thickness 1000 Å on epi-ZnO/sapphire. Excellent crystalline properties of these epi-ZnO/sapphire heterostructures are, thus, promising for lattice-matched substrates for III–V nitride heteroepitaxy and optoelectronics devices.