Wettability of Metal Assisted Chemically Etched (MaCE) Grass Like Silicon Nanowires

Silicon Nanowires also referred as SiNWs are considered as one of the most important one-dimensional materials due to their several unique properties. Here, the silicon nanowires (SiNWs) are grown by a simple metal assisted chemical etching method on silicon substrate via HF treatment. The length and the aspect ratio of the as-prepared SiNWs are varied by etching time (taken 40, 60 and 80 minutes here). Various characterization methods have been employed to evaluate its properties. X-ray diffraction (X-RD) determines the crystallinity of the sample as well as bulk to nano transformation while morphological information is obtained by field emission scanning electron microscope (FESEM). Reflectance spectra of HF modified samples have shown remarkable difference from that of pure silicon wafer. We have obtained band gap of the samples for different etching times using Kubelka-Munk equation. The contact angle (CA) of deionised water (DI) on the SiNWs indicates to the transformation from hydrophilic bulk Si wafer to hydrophobic Silicon nanowire. HF treatment plays an important role which changes the SiNWs surface from superhydrophilic to hydrophobic. 60 minutes of etching time is optimum to obtain a hydrophobic SiNWs. By the coating of low energy solvent, it is possible to transform the substrate from hydrophobic to superhydrophobic.