TiO2 in anatase crystalline structure has strong photo-catalysis. In this paper, TiO2 films are deposited on soda-glass substrate using a Ti cathode vacuum arc with O2 flow. Experimental conditions are as follows: arc current, 50A; pressure, 0.3 and 1.0Pa; O2 flow rate, 20ml/min; cathode-substrate distance, 250mm; bias DC voltage to the substrate, none and-300V. As-deposited films are annealed for 60min under atmosphere and vacuum. The following results were obtained. (1) Deposition rate is 0.07μm/min. (2) As-deposited films are amorphous. (3) Films annealed at 250-500°C have an anatase crystalline structure. These results are independent of pressure, bias, and annealing environment.
In another prosess, the films are deposited for 30min when the substrate holding table is connected to the anode chamber. Experimental conditions are as follows: arc current, 50A; pressure, 1.0Pa; O2 flow rate, 20ml/min; cathode-substrate distance, 250mm. 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°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 prosess is dominantly anatase.
The above experiments show that anatase TiO2 film can be deposited on soda-glass by the reactive vacuum arc method.