Numerical Analysis and Demonstration of Submicron Antireflective Textures for Crystalline Silicon Solar Cells

Submicron surface textures were investigated to reduce the optical loss of Si solar cells. Numerical simulations based on the rigorous coupled-wave approach were performed to obtain the spectral reflectivity of pyramid-type Si textures with submicron period. The results showed that a low mean reflectivity below 3% can be obtained in a wide range of period, and that a suitable combination of period and aspect ratio exists to reduce the reflection loss effectively. Based on the calculation results, tapered subwavelength structures with the period of about 0.1 mum were fabricated on multi-crystalline Si as well as single crystalline Si wafers by fast atom beam etching with a porous alumina mask. A low reflectivity below 2% was successfully obtained from 0.35 to 1.0 mum without AR coatings. Test cells with the SWS showed a gain on the short circuit current density due to the suppression of the optical loss