EPITAXIAL-GROWTH OF ZNO FILMS ON (0001)SAPPHIRE AT LOW-TEMPERATURES BY ELECTRON-CYCLOTRON RESONANCE-ASSISTED MOLECULAR-BEAM EPITAXY AND THEIR MICROSTRUCTURAL CHARACTERIZATIONS

The details of epitaxial growth and microstructural characteristics of ZnO films grown on (0001) sapphire were investigated using X-ray diff raction (XRD), reflection high energy electron diffraction (RHEED), an d plan-view and cross-sectional transmission electron microscopy (TEM) . The films were grown by electron cyclotron resonance-assisted molecu lar beam epitaxy (ECR-assisted MBE). The ECR-assisted MBE was found to be capable of growing high quality epitaxial ZnO films at low tempera tures in comparison with chemical vapor deposition (CVD) and RF sputte ring. The films exhibited a high degree of epitaxy, a sharp interface between film and substrate, and a smooth surface morphology. The TEM o bservations revealed that the films were epitaxial with an orientation al relationship of (0001)ZnO \\ (0001)Al2O3 and [(1) over bar 2 (1) ov er bar 0]ZnO \\ [(1) over bar 100]Al2O3. This is equivalent to a 30 de grees rotation of ZnO relative to sapphire in (0001) plane.