Antireflecting coating from Ta2O5 and SiO2 multilayer films

Sol-gel method is important for depositing antireflective coating that allows control over thickness as well as the index of refraction. Antireflective coatings which are produced from Ta2O5 and SiO2 multi-layer thin films using sol-gel spin coating method are presented. The refractive index and the thickness are controlled by the composition and the concentration of the solution respectively. The thickness, refractive index and extinction coefficient of the films were calculated through transmission and reflection measurement by an NKD analyser. Mechanical properties of the films were checked by the cross tape test and dry sun test at 760 W/m(2). The result shows that the sample heat treated at 450 degrees C for 15 min approaches a reflectance with less than 0.5% at around 840 nm. (C) 2005 Springer Science + Business Media, Inc

Determination of optical properties of amorphous Ta2O5 films deposited by spin- and dip-coating methods

The optical properties of amorphous Ta2O5 films prepared by the sol-gel dip- and spin-coating deposition technique and dried at 60 degrees C have been investigated. Refractive index, extinction coefficient and optical energy gap have been calculated from optical transmission measurements using the Swanepoel method. The films of similar thickness deposited by the two methods were compared. It is shown that the optical properties are dependent on the deposition methods. The energy band gap of the Ta2O5 films is 3.75 +/- 0.12 eV and is independent of the coating methods