Hydrophobic light-trapping structures fabricated on silicon surfaces by picosecond laser texturing and chemical etching

Abstract

Light-trapping structures are fabricated on crystalline (100) silicon (c-Si) surfaces by picosecond (ps) laser irradiation followed by chemical etching. First, 1064-nm ps laser scanning is used to form micropore arrays on c-Si. The ps laser processing causes little reconsolidation of the silicon surface, which is beneficial to achieve precise etching. Control of the laser scanning interval, number of scans, and etching time gives a micro-nano hierarchical structure. In this hierarchical structure, the average diameter of the micropores is 25 to 30 μm, while the size of the finer nanostructures on the micropore inner walls ranges from dozens to hundreds of nanometers. Unlike traditional laser texturing techniques, the whole laser process is carried out without mask and photolithography. The reflectance of the c-Si surface with a micro-nano hierarchical structure is as low as 6% in the wavelength range from 400 to 1000 nm without coating. Moreover, the samples also show good hydrophobicity. This is a potential method to fabricate economical antireflective structures that are ideal for applications in c-Si solar cells and self-cleaning c-Si microelectronic devices.