Reduced porosity in metal-assisted chemical etching of vertical Si nanowire arrays by an induced magnetic field

High aspect ratio silicon nanowires (Si NWs) are produced by metal‐assisted chemical etching (MacEtch) combined with a magnetic field. The vertically applied magnetic field enhances the adhesion between a catalytic metal film and a semiconductor surface. As a result, very uniform Si NWs are formed with increased etch rate due to an easy transfer of holes from metal to Si. Importantly, the porosity of the Si NWs is dramatically reduced by an applied magnetic field because the metal film quickly sinks into the Si, thereby decreasing the excess hole diffusion from the NW sidewall. The combined process of MacEtch and a magnetic field is a promising approach to form high aspect ratio Si NWs with minimized etching damage.