Wet etching after femtosecond laser machining for efficient fabrication of consistent inverted pyramid microstructures on monocrystalline silicon surfaces

Monocrystalline silicon is an important semiconductor material. Monocrystalline silicon with appropriate surface structure has been used in the field of microelectronics and microsolar cells due to its improved mechanical and optical properties. However, due to its brittle and hard properties, the high-quality preparation of microstructures is difficult. In this study, femtosecond laser-assisted wet chemical etching was utilized to fabricate well-defined inverted pyramidal etch pits and array structures on monocrystalline silicon surfaces, while the actual angle between the (100) and (111) crystallographic planes was determined. Firstly, the morphology of ablation holes under different laser parameters was studied. Secondly, wet etching was conducted at 20 °C and 80 °C to investigate the morphology evolution of inverted pyramid etching pits. The optical properties of monocrystalline silicon were tested. The experimental results demonstrate that the inverted pyramid-structured m-Si exhibits an absorptivity exceeding 95 % within the wavelength range of 400–900 nm. This is of great significance for improving the optical performance of monocrystalline silicon.