Vapor-solid-solid grown Ge nanowires at integrated circuit compatible temperature by molecular beam epitaxy

Abstract

We demonstrate Au-assisted vapor-solid-solid (VSS) growth of Ge nanowires (NWs) by molecular beam epitaxy at the substrate temperature of $180 C, which is compatible with the temperature window for Si-based integrated circuit. Low temperature grown Ge NWs hold a smaller size, similar uniformity, and better fit with Au tips in diameter, in contrast to Ge NWs grown at around or above the eutectic temperature of Au-Ge alloy in the vapor-liquid-solid (VLS) growth. Six h110i growth orientations were observed on Ge (110) by the VSS growth at $180 C, differing from only one vertical growth direction of Ge NWs by the VLS growth at a high temperature. The evolution of NWs dimension and morphology from the VLS growth to the VSS growth is qualitatively explained by analyzing the mechanism of the two growth modes. Published by AIP Publishing.

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NO2 gas sensor based on graphene decorated with Ge quantum dots

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