Silica-based antireflection coating by glancing angle deposition

Abstract

In this study, silica-based multilayer graded-index antireflection coatings have been developed by RF magnetron sputtering exploiting the mechanism of glancing angle deposition (GLAD). GLAD is an extension of oblique angle deposition (OAD) where substrate rotation is also applied along with OAD. The optical properties of the films have been tailored by varying the oblique angle of deposition. Each subsequent layer of the multilayer coating has been deposited at a different oblique angle and has different thickness and refractive index. The refractive index of the films reduces successively as we move from the bottom to the top layer achieved by an increase in porosity with a subsequent increase in the flux incidence angle. These multilayer coatings when applied on glass substrates, exhibit a reduction in the average reflectance of glass from 8.75% to 1.6% in a wavelength range of 400-800 nm.