Epitaxial growth of ZnO films on ZnO-buffered Al₂O₃ (0001) in water at 95°C

A very low-temperature (95°C) aqueous solution route has applied to growing epitaxial ZnO films on Al₂O₃ (0001). A 500-nm-thick ZnO film was beforehand deposited on Al₂O₃ (0001) by sputtering as a buffer layer to enhance the homoepitaxial growth of ZnO in the aqueous solution. At an early stage of growth, hexagon-shaped ZnO microcrystals grow. At later stages of growth, the hexagon microcrystals coalesce, finally producing continuous epitaxial films of ZnO, which has been confirmed by high-resolution X-ray diffraction studies.