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 epitaxi ally on sapphire (001) by pulsed laser deposition technique. The omega -rocking curve full width at half-maximum of the ZnO(002) peak for the films grown at 750 degrees C, oxygen pressure 10(-5) Torr was 0.17 de grees. The high degree of crystallinity was confirmed by ion channelin g technique providing a minimum Rutherford backscattering yield of 2%- 3% in the near-surface region (similar to 2000 Angstrom). The atomic f orce microscopy revealed smooth hexagonal faceting of the ZnO films. I t has been possible to deposit epitaxial ALN films of thickness 1000 A ngstrom on epi-ZnO/sapphire. Excellent crystalline properties of these epi-ZnO/sapphire heterostructures are, thus, promising for lattice-ma tched substrates for III-V nitride heteroepitaxy and optoelectronics d evices. (C) 1997 American Institute of Physics.