Optimization of the Dielectric Layer Thickness for Surface-Plasmon-Induced Light Absorption for Silicon Solar Cells

Abstract

In this study, we investigate the effect of dielectric layer thickness on light reflection due to random self-assembled Ag nanoparticles with diameters of less than 160 nm deposited on the Si substrate, indicating that a dielectric layer with an appropriate thickness is useful for reducing the amount of reflected light. In the short wavelength range, reflectivity is determined by the metallic plasmon and the SiO2 antireflection layer, and the effect of the surface plasmon dominates over the antireflection effect. In the long wavelength range, reflectivity decreases with increasing dielectric layer thickness and is determined by the oxide antireflection layer, while the effect of the surface plasmon is negligibly small. Moreover, the surface plasmon is affected by the SiO2 layer and Si substrate when the dielectric layer is thin; however, it is only determined by the SiO2 layer when the oxide layer is sufficiently thick. These observations have substantial applications for the optimization of surface-plasmon-enhanced silicon solar cells.