Preferential face deposition of gold nanoparticles on silicon nanowires by galvanic displacement

Abstract

We report the preferential growth of gold nanoparticles on certain crystallographic facets of Si nanowires (NWs). Our synthetic approach uses galvanic displacement, an electroless deposition method; Si NWs act as the source of electrons required for the reduction of gold ions to metallic gold nanoparticles. Si NWs grown along the <112> growth direction have a characteristic rectangular cross-section with two each of (111) and (110) facets. Through detailed transmission electron microscopy (TEM) and TEM tomography, we were able to show the selective growth of gold nanoparticles on the Si(110) facets of the Si NWs with <112> growth directions; gold deposition was not observed on the Si(111) facets. These results may be related to the high reactivity of Si(110) facets towards gold deposition via galvanic displacement as compared to the reactivity of Si(111) facets.