Array structure of monocrystalline silicon surface processed by femtosecond laser machining assisted with anisotropic chemical etching

Monocrystalline silicon (m-Si) with array structure has excellent optical and surface properties in the application of solar cells and optoelectronics. However, due to its hard and brittle properties, the efficient and high-quality micro-processing of complex array structured m-Si surface is difficult. In this work, micron array structure, such as inverted pyramid (IP) array structure, V-shaped groove array structure, and positive pyramid array structure, was generated on the m-Si surface by an efficient femtosecond laser machining assisted with anisotropic chemical etching. The morphology changes of microholes during the etching process, as well as the surface and optical properties of array structured m-Si, have also been studied. Experimental results showed that V-shaped groove array structure m-Si achieved superhydrophilic performance. The m-Si of IP array structure and V-shaped groove array structure exhibit high absorptivity (>95 %) and low light reflectivity (<5%) within a wide spectral range from 400 to 950 nm. This study reveals that femtosecond laser machining assisted with anisotropic chemical etching is a facile and feasible avenue to produce array structured m-Si with excellent optical performance.