Direct deposition of silica films using silicon alkoxide solution

Dense silica films were directly deposited on a substrate in basic solutions (∼pH 11) of tetraethoxysilane (TEOS) at temperatures <60°C. The film formation was observed through heterogeneous nucleation on a hydrophilic surface with the intermediate condition between gel formation and stable solution. The refractive index, the OH content and the hardness indicate that the structure of the deposited films are similar to that of sol-gel silica films calcined at 500°C. We suggest that the growth and the densification of the films occur simultaneously during the deposition in the solutions.