Wetting and tribological properties of nano-engineered surfaces modified with OTS SAMs

Adhesion and friction are detrimental issues in micro-electro-mechanical systems (MEMS). Current solutions include reducing the contact area between surfaces, by surface texturing or improving surface hydrophobicity by applying materials with low surface energy on the surfaces. The largest reported water contact angle (WCA), which is an indication of surface hydrophobicity, of a chemically modified smooth surface is less than 120°. In this thesis research, a novel MEMS fabrication process compatible nano-surface-engineering method for generating superhydrophobic surfaces with WCA greater than 150° has been developed by combining micro-/nano-textures produced by aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) and Octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs). OTS deposition conditions were optimized to achieve the best surface hydrophobicity. The wetting and tribological properties of OTS SAMs modified micro-/nano-textured surfaces were systematically studied. The results showed that both properties were improved significantly compared to those of smooth Si surfaces with and without OTS.