TiO 2 in anatase crystalline structure has strong photocatalysis. In this paper, TiO 2 films are deposited on sodaglass substrate using a Ti cathode vacuum arc with O 2 flow. Experimental conditions are as follows: arc current, 50 A; pressure, 0.3 and 1.0 Pa; O 2 flow rate, 20 ml/min; cathode substrate distance, 250 mm; bias dc voltage to the substrate, none and 300 V. As-deposited films are annealed for 60 min under atmosphere and vacuum. The following results were obtained. (1) Deposition rate is 0.07 mm/min. (2) As-deposited films are amorphous. ( 3) Films annealed at 250 to 500 Β°C have an anatase crystalline structure. These results are independent of pressure, bias, and annealing environment.
In another process, the films are deposited for 30 min when the substrate holding table is connected to the anode chamber. Experimental conditions are as follows: arc current, 50 A; pressure, 1.0 Pa; O 2 flow rate, 20 ml/min; cathodesubstrate distance, 250 mm. Almost 30% of the arc current was observed to flow through the substrate table, and the surface temperature of the table increased up to 450 Β°C. The reason for this is considered to be that Joule heating occurs when the current flows through the film deposited on the table. The film deposited in this process is dominantly anatase.
The above experiments show that anatase TiO 2 film can be deposited on soda-glass by the reactive vacuum arc method.