Fabrication of graded refractive index 3-dimensional anti-reflection structure using self-assembled SiO2 nano particles

A new fabrication method for graded refractive index anti-reflection structure was proposed. Using self-assembled nano-scale silica particles as an etching mask on the first dielectric layer, an arrayed conic-shaped structure was fabricated. Deposition of second material on that textured dielectric film completed the dual-layer anti-reflection structure. We applied ZnS as the first layer and SiO₂ as the second layer. This fabricated 3-dimensional anti-reflection structure (ARS) demonstrated lower averaged reflectivity than a conventional planar dual-layer anti-reflection coating, the thickness of which had been optimized for a GaAs single-junction PV. The averaged reflectance on the fabricated ARS was 2.58% in the wavelength of 350-850nm demonstrated on the Si substrate. Finally, the ARS was applied to a GaAs single-junction PV, leading to enhanced external quantum efficiency (EQE) which is consistent with the reflectance spectrum.