Influence of H2O on structure of base-catalyzed porous SiO2 antireflective coatings

Abstract

Silica antireflective coatings were deposited on KB-7 glass substrates by sol-gel method. The sols were produced via ammonia catalysis tetraethylorthosilicate (TEOS) diluted in ethanol, using different molar ratio, R, of H2O/TEOS. The influence of amount of water on structure of coatings was investigated by measuring thickness, refractive index, and infrared spectrum of the coatings and BET surface area of the dried gel silica power. The results revealed that the thickness and the refractive index were decreased with the increase of R, whereas the surface area was increased with the increase of R. The infrared spectra indicated that the densification of coating reduced with increase of R.