Heteroepitaxy of SnO2 thin films on m-plane sapphire by MOCVD

SnO2 thin films have been deposited on (101̄0) m-plane sapphire substrates by metalorganic chemical vapor deposition (MOCVD) in the temperature range 500–750°C. X-ray diffraction showed that the films were pure SnO2 with rutile structure and the film orientation was dependent on the growth temperature. Single crystalline SnO2 (001) film was fabricated at 700°C, which was confirmed by cross-sectional transmission electron microscopy and electron diffraction. A clear in-plane relationship of [010]SnO2‖[0001] Al2O3 and [100]SnO2‖[12̄10] Al2O3 was determined between the film and the substrate. The samples showed high transparency of ∼80% in the visible range. Photoluminescence (PL) spectra measured at room temperature revealed that the film grown at 700°C showed a weak PL band near 600nm, while a strong PL band centered at about 480nm was detected at 13K. The PL mechanism is discussed in detail.