High Conductive TiO2 Films Due to Auto Doping by Hot Wire CVD Method for Protecting Material of TCO Against Atomic Hydrogen Exposures

TiO₂ films as a protecting material of transparent conducting oxide (TCO) against atomic hydrogen exposures for Si thin film solar cells have been prepared by hot wire CVD method. It is found that dark conductivity of the film at room temperature reaches to the order of 10^-1 S/cm. This value is 3 orders of magnitude higher than that of Nb-doped TiO₂ films by RF magnetron sputtering method in our previous studies. The improvement of the dark conductivity is mainly due to auto doping of tantalum (Ta) from the filament. Structural and optical properties of the film are also reported