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/m2. The result shows that the sample heat treated at 450∘C for 15 min approaches a reflectance with less than 0.5% at around 840 nm.