Using Self-Assembled Nanoparticles to Fabricate and Optimize Subwavelength Textured Structures in Solar Cells

Abstract

This paper reports the preparation of optimal textured structures on silicon surfaces through metal-assisted etching using gold nanoparticles (Au NPs) as catalysts in HF/H 2 O 2 solution. The size and density of the NPs on the Si substrates were readily and rapidly determined using spectroscopic ellipsometry. We obtained uniformly textured Si layers containing cylindrical, conical, and bowl-shaped features after immersing the Au-deposited Si substrates in a mixture of HF and H 2 O 2 under various etching conditions. A textured surface possessing close-packed pyramidal features with dimensions on the subwavelength scale exhibited the lowest reflectance (<0.5%) over the entire visible and near-IR spectrum. This low reflectance arose from the refractive index gradient of the Si surface and light trapping phenomena. We used a 3D finite-difference time domains simulation to examine the distribution of light propagating on the textured structures within the near-field regime.