The influence of oxygen flow rate on properties of SnO2 thin films grown epitaxially on c-sapphire by chemical vapor deposition

Abstract Tin dioxide (SnO 2 ) thin films were grown on c -plane sapphire substrates by chemical vapor deposition using SnI 2 and O 2 as reactants. The growth experiments were carried out at a fixed substrate temperature of 510 °C and different O 2 flow rates. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, UV–Vis–IR spectrophotometry and Hall-effect measurement were used to characterize the films. All films consisted of pure-phase SnO 2 with a rutile structure and showed an epitaxial relationship with the substrate of SnO 2 (100)||Al 2 O 3 (0001) and SnO 2 [010]||Al 2 O 3 . The crystalline quality and properties of the films were found to be sensitively dependent on the O 2 flow rate during the film growth. The absolute average transmittance of the SnO 2 films exceeded 85% in the visible and infrared spectral region. The films had optical band-gaps (3.72–3.89 eV) that are in line with the band gap of single-crystal SnO 2 . The carrier concentration and Hall mobility of the films decreased from 3.3 × 10 19 to 9 × 10 17  cm − 3 and from 19 to 2 cm 2  V − 1  s − 1 , respectively, while the resistivity increased from 0.01 to 3 Ω cm with increasing of the O 2 flow rate from 5 to 60 sccm.