Fabrication of controllable wettability of crystalline silicon surfaces by laser surface texturing and silanization

Abstract

This paper aims to explore the effects of laser surface texturing and chemical modifications by silanization on the wettability of silicon surfaces. To effectively prepare super-hydrophobic surfaces on silicon, a process using laser texturing with following silanization treatment is used to modify the surface. The surface wettability is evaluated by water contact angle (WCA). To ascertain the effect of laser texturing on wettability, the morphological and metallurgical modifications of the surface were investigated by scanning electron microscopy (SEM), white light confocal microscope and X-ray photoelectron spectroscopy (XPS). It is found that the fresh laser-processed silicon surface is super-hydrophilic, which is in line with the Wenzel model. A super-hydrophobic surface with a WCA >150° was successfully obtained after silanization treatment. Silanization by a concentration of 0.72 wt% 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane with 2 h of immersion time was found to be the most effective condition for achieving super-hydrophobic silicon surfaces. The effects of acids, alkalis and salts on wettability have also been assessed. The results indicate that as-prepared silicon samples with a fluoride coating can be normally used in acid condition but not suitable for use in alkaline and salty environments.