Synchrotron x-ray scattering study of SnO2 thin film grown on sapphire

From synchrotron x-ray scattering measurements, it was found that epitaxially grown SnO2 film on sapphire has a variant structure with threefold symmetry with respect to the substrate and that the ultrathin interfacial layer is formed due to the lattice mismatch between SnO2 and Al2O3. The physical properties of the top surface, such as surface morphology, height profile, and roughness, were determined by atomic force microscopy. The height profiles of the film grown at 600 °C and room temperature revealed the asymmetrical and the ordinary symmetric Gaussian distributions, respectively. The difference originates from the dominant diffusion process at high substrate temperature.