Impact of micro-texturization on hybrid micro/nano-textured surface for enhanced broadband light absorption in crystalline silicon for application in photovoltaics

Abstract

This paper reports investigation on hybrid micro/nanotextures for enhanced broadband absorption in crystalline silicon(c-Si) for application in photovoltaics. Microscale pyramids are fabricated using sodium hydroxide (NaOH) solution, etched at different durations. Nanowires on pyramids are formed using metal-assisted chemical etching (MACE). With 30 min of NaOH etching, pyramids with 3–5 μm heights (3–7 μm widths) are formed. The pyramids reduce broadband reflection of the c-Si through enhanced scattering. After MACE, nanowires with 450–600 nm heights (30–40 nm widths) are obtained. With the nanowires, weighted average reflection (WAR) for all samples reduces significantly, owing to enhanced light coupling by the nanowires and increased light scattering by the pyramids. The sample with 30 min NaOH etching and MACE demonstrates WAR of 7.5%, which is the lowest broadband reflection achieved in this work. This corresponds to potential Jsc(max) of 38.7 mA/cm2, or 13.5% enhancement compared to the Jsc(max) of the pyramids alone.