Deposition of TiO2 on silicon by sputtering in hollow cathode

In the present work we use a plasma jet system with a hollow cathode to deposit thin TiO2 films on silicon substrates. The cylindrical cathode, made from pure titanium, can be negatively polarized between 0 and 1200 V and supports an electrical current of up to 1 A. An Ar/O2 mixture, with a total flux of 20 sccm and an O2 percentage ranging from 0 to 20%, is passed through a cylindrical hole machined in the cathode. The influence of the cathode's parameters on the properties of deposited TiO2 films and their deposition rate is studied. When discharge occurs, titanium atoms are sputtered/evaporated. They are transported by the jet and deposited on the Si substrates located on the holder placed facing the plasma jet system at a distance ranging from 10 to 50 mm from the cathode. The working pressure is 10−3 mbar and the deposition time is 10–60 min. The deposited films are characterized by X-ray diffraction to analyze qualitatively the phases present.