Investigation of ZnOrsapphire interface and formation of ZnO nanocrystalline by laser MBE

Epitaxial ZnO thin films were prepared on atomically flat sapphire a-Al2O3. 0001.substrates at various substrate temperatures by laser molecular beam epitaxy. Crystal structure was analyzed by four-circle X-ray diffraction. Atomic force microscope AFM.and reflection high energy electron diffraction RHEED.were used to evaluate surface morphology. When ZnO was deposited on atomically flat sapphire 0001., an epitaxial ZnO film was grown with c-axis orientation, having two different in-plane orientation, ZnOw1010xIsapphirew1010x 400–4508C.and ZnOw1010xIsapphirew1120x 800–8358C., depending on deposition temperature. The detailed observation of the initial growth of ZnO film deposited at 8358C revealed that the growth mode followed Stranski–Krastanov growth mechanism. q2000 Elsevier Science B.V. All rights reserved.