Ion Flux Characteristics in Pulsed Dual Magnetron Discharges Used for Deposition of Photoactive TiO2 Films

Pulsed dc dual magnetron sputtering was used for preparation of photocatalytic crystalline TiO2 films. The depositions were performed in an Ar + O-2 gas mixture at a total pressure of 0.9 Pa with an oxygen partial pressure of 0.2 Pa. The maximum substrate surface temperature was 160 degrees C. Both magnetrons operated in the same asymmetric bipolar mode at the repetition frequency of 100 kHz with a fixed 50% duty cycle, but their operations were shifted by a half of the period. Time-averaged energy-resolved mass spectroscopy was performed at a substrate position located 100 mm from the targets. A suppression of high-energy ions in the flux onto the substrate resulted in a strong predominance of the highly photoactive crystalline anatase phase in the TiO2 films.