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

Tin dioxide (SnO2) thin filmswere grownon c-plane sapphire substrates by chemical vapor deposition using SnI2 and O-2 as reactants. The growth experiments were carried out at a fixed substrate temperature of 510 degrees 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 SnO2 with a rutile structure and showed an epitaxial relationship with the substrate of SnO2(100)parallel to Al2O3(0001) and SnO2[010]parallel to Al2O3<11-20>. 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 SnO2 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 SnO2. The carrier concentration and Hall mobility of the films decreased from 3.3 x 10(19) to 9 x 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 Omega cm with increasing of the O-2 flow rate from 5 to 60 sccm. (C) 2015 Elsevier B.V. All rights reserved.