Wettability of Silicon Carbide Nanowires

Wettability can be defined as the degree of adhesion of a liquid in contact with a surface. The evaluation of wettability can be done by measuring the contact angle that a drop forms on a surface. The value of the contact angle defines a hydrophilic or hydrophobic surface. The wettability of surfaces is very important according of the type of applications: in particular, biology and nanomedicine applications requires not only biocompatible materials, but also hydrophilic surfaces. Silicon carbide (SiC) is a biocompatible material and its nanostructures, such as nanowires (NW), has a high value of area/volume ratio that allows greater contact with a biological fluid. Two different type of nanowires have been prepared by Chemical Vapour Deposition (CVD) and Vapour Phase Epitaxy (VPE) to obtain core-shell (SiC/SiO2/Si) and pure silicon carbide (SiC/Si) NWs, both grown on silicon substrate. Pure silicon carbide NWs were obtained in VPE system using Ni and Fe as catalyst deposited with sputtering with a thickness ranging from 2 to 4 nm1. In CVD apparatus the same catalysts were used, but were deposited on the substrate by drop casting a ethanol solution of nickel and iron salts2. The morphology of the prepared samples was evaluated by SEM. All samples were treated with plasma in hydrogen to remove impurities due to growth residues3. Water contact angle measurements on samples, both as grown and treated with plasma, were compared: samples treated with plasma show a lower contact angle (better wettability) with respect to the surface without plasma treatment. A comparison with the respective flat epitaxial surface will be given. Preliminary biological tests conducted with MC3T3-E1 (murine osteoblasts) cell line on NWs showed an increase in terms of cells proliferation and viability on the substrate with plasma treatment than on control NWs.