A Robust Metal-Assisted Etching Process for Ag-Catalyzed Texturing of Silicon

Silicon structures with excellent light-trapping performance have been developed using a silver-catalyzed metal-assisted etching (MAE) process. The MAE process can be well controlled through variation in solution composition and exposure times, even when the process is conducted on obscured, polished, 〈1 1 1〉 surfaces. Light trapping was calculated to be >90% of Lambertian for the best performing sample, with solar weighted average reflectance (R<inf>w</inf>) of 13% when λ 400-1000 nm. This represents an 18% reflectance reduction compared with a planar sample and 13% improvement compared with a sample with conventional isotexture. This was improved further by encapsulation of the sample, reducing R<inf>w(400-1000 nm)</inf> for the MAE-textured sample to 2%. The structures were well passivated using atomic layer deposition and demonstrate surface recombination velocities (S<inf>eff</inf>) of ≈ 30 cm·s-1 at injection levels of Δn = 1015 cm-3.