Switchable wetting & flexible SiC thin film with nanostructures

In this paper, we present the fabrication of flexible surface-nanostructured silicon carbide (SiC) membrane, whose wettability can be simply tuned from superhydrophobicity to super-hydrophilicity via the combination of an improved deep reactive ion etching (DRIE) process and KOH wet etching process. The thermal annealing is utilized to reduce the stress of SiC membrane produced by plasma enhanced chemical vapor deposition (PECVD) process. High-dense SiC nano-balls are fabricated by the improved DRIE process via the passivation enhancement. Resulting from both the minimized liquid-solid contact area and the fluorocarbon layer atop deposited during the DRIE process, the SiC film with nano-balls shows a reliable superhydrophobicity. Furthermore, after the removal of silicon substrate by KOH wet etching, the flexible SiC membrane with nano-tips is realized, and the wetting behavior switches to superhydrophilicity. The static contact angle (CA) remarkably achieves more than 160° and less than 1°, respectively.