Polarity effects of substrate surface in homoepitaxial ZnO film growth

Epitaxial ZnO films were grown on two polar surfaces (O-surface and Zn-surf ace) of (0001) ZnO single-crystal substrates using off-axis magnetron sputt ering deposition. It was found that the two polar ZnO surfaces have differe nt surface structure and morphology, which strongly influence epitaxial fil m growth. An interesting result shows that high-temperature annealing of Zn O single crystals will improve the surface structure on the O-terminated su rface rather than the opposite surface. The morphology and structure of hom oepitaxial films grown on the ZnO substrates were different from heteroepit axial films grown on the Al2O3. The measurements of low-angle incident X-ra y diffraction and atomic force microscopy of ZnO films indicate that the O- terminated surface is better for ZnO epitaxial film growth. (C) 2000 Publis hed by Elsevier Science B.V.