Epitaxial Insertion of Gold Silicide Nanodisks During the Growth of Silicon Nanowires

Abstract

Nanodisk-shaped, single-crystal gold suicide heterojunctions were inserted into silicon nanowires during vapor-liquid-solid growth using Au as a catalyst within a specific range of chlorine-to-hydrogen atomic ratio. The mechanism of nanodisk formation has been investigated by changing the source gas ratio of SiCl4 to H-2. We report that an over-supply of silicon into the Au-Si liquid alloy leads to highly supersaturated solution and enhances the precipitation of Au in the silicon nanowires due to the formation of unstable phases within the liquid alloy. It is shown that the gold precipitates embedded in the silicon nanowires consisted of a metastable gold suicide. Interestingly, faceting of gold suicide was observed at the Au/Si interfaces, and silicon nanowires were epitaxially grown on the top of the nanodisk by vapor-liquid-solid growth. High resolution transmission electron microscopy confirmed that gold suicide nanodisks are epitaxially connected to the silicon nanowires in the direction of growth direction. These gold suicide nanodisks would be useful as nanosized electrical junctions for future applications in nanowire interconnections.