Open AccessPlasma nanotexturing of silicon surfaces for photovoltaics applications: influence of initial surface finish on the evolution of topographical and optical properties
Author(s) -
Guillaume Fischer,
Etienne Drahi,
Martin Foldyna,
Thomas A. Germer,
Erik Johnson
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.0a1057
Subject(s) - materials science , surface finish , surface roughness , optics , silicon , etching (microfabrication) , photovoltaics , plasma etching , light scattering , wafer , scattering , nanostructure , optoelectronics , plasma , texture (cosmology) , nanotechnology , composite material , photovoltaic system , layer (electronics) , ecology , physics , image (mathematics) , quantum mechanics , artificial intelligence , computer science , biology
Using a plasma to generate a surface texture with feature sizes on the order of tens to hundreds of nanometers ("nanotexturing") is a promising technique being considered to improve efficiency 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.