Surface-migration driving uniform amorphous shell on crystalline nanowire: the case of SiC/SiOx core–shell nanowires

Abstract

Single-crystal SiC nanowires with controlled surface amorphous silicon oxide (SiO_x) layers, including bare SiC nanowires, chain-like and cable-like SiC/SiO_x nanowires, have been synthesized by a catalyst-assisted chemical vapor reaction approach, and the temperature-dependent morphology evolution of the surface amorphous layers is investigated in detail. Morphological, compositional and structural characterizations indicate that as-synthesized SiC nanowires consist of cubic phase single crystal cores with [111] growth direction and amorphous SiO_x shell with varied morphology that can be tuned by temperature. The growth of the SiC nanowires is governed by the vapor–liquid–solid mechanism while the variation of surface SiO_x amorphous layers is thought to be controlled by a surface migration process that is mainly dependent on temperature. The results would be helpful to achieve rational modulation of amorphous surface layers on semiconductor nanowires.