Nanostructured porous SiO2 films for antireflection coatings

Thin films with a low refractive index play an important role in optics, optoelectronics, and microelectronics. In this study, we present nanostructured porous SiO2 films fabricated by using a glancing angle deposition technique. These nanostructured porous SiO2 films deposited at an angle of 85° show very low refractive indices of 1.08 at 633 nm. As an application, a four-layer antireflection coating for visible wavelength is designed and fabricated using SiO2 material only. The normal incidence reflectance of the antireflection coating averaged between 400 and 800 nm is about 0.04%. The microstructure and the surface morphology are also investigated by using a scanning electron microscope.

Research Highlights
► Nanostructured porous SiO2 films using glancing angle deposition show low refractive index of 1.08 at 633 nm
► Four-layer antireflection coating of ~ 0.04% reflectance in the visible