Ultra-fast vapour–liquid–solid synthesis of Si nanowires using ion-beam implanted galliumas catalyst

Abstract

The feasibility of gallium as a catalyst for vapour–liquid–solid (VLS) nanowire (NW)growth deriving from an implantation process in silicon by a focused ion beam(FIB) is investigated. Si(100) substrates are subjected to FIB implantation ofgallium ions with various ion fluence rates. NW growth is performed in a hot wallchemical vapour deposition (CVD) reactor at temperatures between 400 and500 °C with2% SiH4/He as precursor gas. This process results in ultra-fast growth of⟨112⟩- and⟨110⟩-oriented Si-NWs with a length of several tens of micrometres. Further investigation bytransmission electron microscopy indicates the presence of a NW core–shell structure: whilethe NW core yields crystalline structuring, the shell consists entirely of amorphousmaterial.