Optical Property of Porous Silicon Produced by Metal-Assisted Etching

Abstract

Antireflection of Si surface is an important technology to increase the photocurrent density of solar cells. Recently, porous Si has been researched for replacing Si nitride which is common material of antireflective coating (ARC). In this study, we have investigated the optical properties of porous Si thin films, thinner than doped layers for p-n junction formation of Si solar cells, produced by metal-assisted etching. The structure of porous Si is changed with the size of catalytic Ag nanoparticles, composition of etching solution, and etching time. The reflection of porous film formed Si wafers is much lower than that of mirror polished wafers. Reflectance spectra and ellipsometric analysis indicate that the thin porous Si films act as optical films and they are expected to function as suitable ARC for crystalline Si solar cells.