Effect of Oxygen Partial Pressure on the Electrical and Optical Properties of DC Magnetron Sputtered Amorphous TiO2 Films

Titanium dioxide (TiO2) thin films were deposited on p-Si (100) and Corning glass substrates held at room temperature by DC magnetron sputtering at different oxygen partial pressure in the range 9 x 10(-3)-9 x 10(-2) Pa. The influence of oxygen partial pressure on the structural, electrical, and optical properties of the deposited films was systematically studied. XPS studies confirmed that the film formed at an oxygen partial pressure of 6 x 10(-2) Pa was nearly stoichiometric. TiO2 films formed at all oxygen partial pressures were X-ray amorphous. The optical transmittance gradually increased and the absorption edge shifted towards shorter wavelengths with the increase of oxygen partial pressure. Thin film capacitors with configuration of Al/TiO2/p-Si have been fabricated. The results showed that the leakage current density of films formed decreased with the increase of oxygen partial pressure to 6 x 10(-2) Pa owing to the decrease in the oxygen defects in the films thereafter it was increased. The current transport mechanism in the TiO2 thin films is shown to be Schottky effect and Fowler-Nordheim tunnelling currents.