Epitaxial growth of zinc oxide thin films on epi-GaN/sapphire (0001) by sol-gel technique

Epitaxial ZnO film has been grown using an epi-GaN buffer layer on sapphire (0001) substrate by sol-gel technique. The 2θ curve full width at half maximum of the ZnO (0002) peak for the film annealed at optimized temperature of 600 °C, was found to be 0.07° from X-ray diffraction spectrum. The atomic force microscopy revealed smooth hexagonal faceting of the ZnO films. Photoluminescence spectrum at room temperature exhibits a sharp exciton emission with a line width of 120 meV with negligible deep level emission. The observed six fold symmetry in reflection high energy electron diffraction pattern confirms the epitaxial nature of the ZnO film.