Sol-gel derived SiO₂ antireflective coatings

Silica antireflective coatings were prepared by sol-gel method with TEOS as precursor and NH₄OH as catalyst. The influence of silica concentration on the transmittance of the coatings, and the dip-coated withdrawal rate on the transmittance and surface roughness of coatings were studied. The results show that the silica concentration has important influence on the antireflective wavelength scope of coatings. For a given wavelength, the transmittance of the coatings increases first, then decreases when increasing the withdrawal rate, maximum transmittance appears at around 100 mm/min for the wavelength of 1064 nm. The surface roughness of the coatings is better at lower withdrawal rate.