Broadband Low Reflection Surfaces With Silicon Nano-tube Square Arrays And Quantum Dot Layers

Abstract

In this study, we take as a starting nanostructure which is already optimized in terms of the silicon nanopillar arrays’ structure pillar height, pillar diameter, and filling ratio such that the optical reflection from its surface is very low (weighted average reflection 3.75 percent). Full-field Finite Difference Time Domain method is used to simulate electric and magnetic fields and calculate the reflection from the modified nanostructured substrate surfaces in 400nm-1100nm spectral range. In this paper, we present the optimization of the structure in terms of the silicon nanotube structure cavity diameter, step coverage of the dielectric thin film. As a result, the weighted reflection is decreased to 3.35 percent. We also want to simulate the quantum dot solution layer deposited over the nanostructure. We modeled the quantum dots as Lorentz dielectric and decreased the optical reflection even lower level of 3.1 percent. Optimization recipe is clearly presented, and the developed method is not only useful for square arrays but also for regular arrays of nanopillars in general for photovoltaic devices.