Heteroepitaxy of SnO 2 thin films on m-plane sapphire by MOCVD

Abstract

SnO 2 thin films have been deposited on (1 0 1̄ 0) 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 SnO 2 with rutile structure and the film orientation was dependent on the growth temperature. Single crystalline SnO 2 (0 0 1) film was fabricated at 700 °C, which was confirmed by cross-sectional transmission electron microscopy and electron diffraction. A clear in-plane relationship of [0 1 0]SnO 2‖[0 0 0 1] Al 2O 3 and [1 0 0]SnO 2‖[1 2̄ 1 0] Al 2O 3 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 600 nm, while a strong PL band centered at about 480 nm was detected at 13 K. The PL mechanism is discussed in detail.