Selective growth of metal-free silicon nanowire mat by chemical vapor deposition on hexagonal boron nitride film

The one-dimensional form of silicon (Si) has been attracting significant scientific and industrial interest again in the field of Li-ion batteries as well as electronic devices, offering higher reversible capacity than carbon materials in an anode. In this work, a new method to grow a uniform Si nanowire mat without metallic nanoparticles was developed, and the growth conditions and conformational properties were also characterized. It is suggested that Si nanowire could be grown by the charge transfer through the hexagonal boron nitride (h-BN) film from the Cu foil as the previously reported graphene growth on the h-BN film on Cu. Web-like bundles of Si nanowires or nanoclusters could be selectively grown on this h-BN/Cu substrate by controlling the substrate temperature during Si deposition. The morphology and chemical composition of the Si nanowire mats, therefore, were systematically characterized using scanning tunneling microscopy, atomic force microscopy, and X-ray photoemission spectroscopy. When decoupled from the metal by a thin h-BN film during the growth, this pristine Si nanowire mat can provide promising technical breakthroughs for anode applications in Li-ion batteries.