Effect of oxygen flow rate on ITO thin films deposited by facing targets sputtering

Tin-doped indium oxide (ITO) thin films were deposited on glass substrates at various oxygen flow rates using a planar magnetron sputtering system with facing targets. In this system, the strong internal magnets inside the target holders confine the plasma between the targets. High resolution transmission electron microscopy revealed a combination of amorphous and crystalline phases on the glass substrate. X-ray photoelectron spectroscopy suggested that the decrease in carrier concentration and increase in mobility were caused by a decrease in the concentration of Sn4+ states. The electrical and optical properties of the ITO films were examined by Hall measurements and UV–visible spectroscopy, which showed a film resistivity and transmittance of 4.26 × l0−4 Ω cm, and > 80% in the visible region, respectively.