Using self-assembled nanoparticles to fabricate and optimize sub-wavelength 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/H2O2 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 H2O2 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.