LAYER-BY-LAYER GROWTH OF EPITAXIAL SNO2 ON SAPPHIRE BY REACTIVE SPUTTER DEPOSITION

Epitaxial films of stoichiometric tin oxide were grown on sapphire (1102BAR) substrates by reactive sputter deposition. X-ray diffraction showed the films to have a single (101) orientation. Lateral registry of film growth with respect to the substrate lattice was demonstrated by low energy electron diffraction. Atomic force microscopy was used to examine surface morphology and roughness. The films are extremely flat, having a rms roughness of 3 angstrom over a 4 X 4 mum2 area. Atomic steps, observed on the sapphire substrate and attributable to a 0.24-degrees miscut, were also observed on the surface of a 400 angstrom film. The results indicate that the film grew via a layer-by-layer growth mechanism which was controlled by diffusion of the adatoms to the step edges.