Double-layer anti-reflection coating using MgF2 and CeO2 films on a crystalline silicon substrate

Abstract This paper describes an investigation of double-layer anti-reflection (DLAR) coatings with MgF 2 and CeO 2 films. We obtained CeO 2 films with a refractive index between 2.3 and 2.4, a surface state density of approximately 10 11 eV −1 cm −2 , and a similar lattice mismatch to silicon substrate. The CeO 2 film grown at 400°C exhibited a (111) preferred orientation and the lowest surface roughness of 6.87 A. The refractive index for the MgF 2 film exhibited approximately 1.386 for most of the film growth temperatures. A theoretically optimized DLAR coating was found to have an average reflectance as low as 1.87% when wavelengths ranged from 0.4 μm to 1.1 μm.