Aqueous synthesis of silicon nanowire arrays and core-shell structures via electroless nanoelectrochemical process

In the present study, we have demonstrated the synthesis of large-area vertically aligned silicon nanowire (SiNW) arrays in an aqueous solution containing AgNCh and HF on p-type (001) Si substrate by self-selective electroless etching process. The fabrication process was rather simple and rapid compared to the well-known Vapor-Liquid-Solid (VLS) growth via chemical-vapor deposition (CVD) and other highvacuum techniques. In this work, the temperature of electrolyte and etching duration were varied in order to achieve different stages of nanowire formation. Diameters of the SiNWs obtained varied from 50 nm to 200 nm and their lengths ranged from several to approximately a few tens of μm, depending on the reaction time and the electrolyte conditions used. Te-Si and Bi₂Te₃-Si core-shell structures were subsequently obtained via galvanic displacement of SiNWs in acidic HF electrolytes containing Bi ³⁺ and Bi³⁺/HTeO₂⁺ ions respectively.