Epitaxial relationships and optical properties of SnO2 films deposited on sapphire substrates

SnO2 thin films were grown using metalorganic chemical vapor deposition (MOCVD) system on sapphire substrates with three different orientations: r-cut image, a-cut image, and m-cut image. All the deposited films were epitaxial rutile films. The epitaxial orientation relationships were determined by X-ray Φ-scans: [0 1 0]SnO2||[1 0 0]Al2O3 and image for the r-cut substrate; [0 1 0]SnO2||[0 0 1]Al2O3 and image for the a-cut substrate; [0 1 0]SnO2||[0 0 1]Al2O3 and [1 0 0]SnO2||[0 1 0]Al2O3 for the m-cut substrate. The X-ray rocking curves yielded full width at half maximum (FWHM) of 0.78°, 1.32° and 0.70° for the (1 0 1) and (0 0 2) reflections of the SnO2 films on r-, a-, and m-cut sapphire substrates, respectively. The room-temperature photoluminescence (PL) spectra of SnO2 films grown on a-cut and m-cut substrates only showed a broad deep-level luminescence band. While a UV band-edge luminescence peak was observed for the film grown on r-cut substrate.