Epitaxial Bottom-up Growth of Silicon Nanowires on Oxidized Silicon by Alloy-Catalyzed Gas-Phase Synthesis

High-yield epitaxial bottom-up growth of silicon nanowires is still challenging but desirable for various applications such as antireflective coatings, solar cells, and high-aspect-ratio scanning probes. Hence, pristine single-crystalline silicon surfaces are, in principle, required as a growth substrate, but reoxidation occurring prior to nanowire growth obstructs epitaxial growth significantly. Here, we present an approach that relies on Al/Au alloy catalysts for gas-phase silicon nanowire synthesis, allowing intrinsically an in situ removal of a native silicon-oxide layer during the initial growth stages. This approach yields reliable and superior epitaxial growth of silicon nanowires on single-crystalline silicon substrates.