Plasma nanotexturing of silicon surfaces for photovoltaics applications: Influence of initial surface finish on the evolution of topographical and optical properties

Published: November 27, 2017

Author(s)

Guillaume Fischer, Etienne Drahi, Martin Foldyna, Thomas A. Germer, Erik V. Johnson

Abstract

Using a plasma to generate a surface texture with feature sizes on the order of nanometers (“nanotexturing”) is a promising technique being considered for application in thin, high- efficiency crystalline silicon solar cells. This study investigates the evolution of the optical properties of silicon samples with various initial surface finishes (from mirror polish to various states of micron-scale roughness) during a plasma nanotexturing process. It is shown that during said process, the appearance and growth of nanocone-like structures are essentially independent of the initial surface finish, as quantified by the auto-correlation function of the surface morphology. During the first stage of the process (2 min to 15 min etching), the reflectance and light-trapping abilities of the nanotextured surfaces are strongly influenced by the initial surface roughness; however, the differences tend to diminish as the nanostructures become larger. For the longest etching times (15 min or more), the effective reflectance is less than 5% and a strong anisotropic scattering behavior is also observed for all samples, leading to very elevated levels of light-trapping.
Citation: Optics Express
Volume: 25
Issue: 24
Pub Type: Journals

Keywords

black silicon, light-trapping, plasma nanotexturing, silicon photovoltaics
Created November 27, 2017, Updated December 22, 2017