Preparation of TiO 2-doped ZnO films by radio frequency magnetron sputtering in ambient hydrogen–argon gas

Abstract

Highly conductive, transparent TiO 2-doped ZnO films are grown by radio frequency (RF) magnetron sputtering in ambient hydrogen–argon (Ar + H 2) gas at a temperature of 150 °C and the effects of the Ti and H 2 content on the structural, electrical, and optical properties of these TiO 2-doped ZnO films are subsequently investigated. X-ray photoelectron spectroscopy examination indicates that the variation of the H 2 content in Ar has an influence upon the chemical state of the films. The X-ray diffraction spectra indicate that all the samples are polycrystalline ZnO films oriented perpendicular to the substrate surface ( c-axis orientation). The lowest resistivity, 6.50 × 10 −4 Ω cm, is obtained with 1.28 wt.% Ti and H 2 content in a 15% Ar ambient. The optical transmittance for TiO 2-doped ZnO films in the visible region is about 85%. Due to the Burstein–Moss effect, the energy band gap increases with the carrier concentration.