Published online by Cambridge University Press: 28 July 2011
We have characterized the structure of epitaxial Al2O3 films deposited on Si (111) substrate using electron beam evaporation from a high-purity single crystal sapphire source in a molecular beam epitaxy (MBE) approach. The structural studies were carried out mainly by single crystal x-ray diffraction with the initial epitaxial growth observed by in-situ reflection high energy electron diffraction. The Al2O3 films grow in the cubic γ-phase with a very uniform thickness, and a high structural perfection. The <111> axes of the film and the Si substrate are well aligned. A mosaic scan of the Al2O3 (222) peak (with no in-plane component) finds a 0.3 degree (or 18') spread. All three unit cell vectors of the film and the substrate are parallel, but the in-plane cone scans of the {004} and {044} diffraction peaks about the surface normal find a ±3 degree film in-plane rotation with respect to the substrate surface orientation.