Direct synthesis of single-crystalline silicon nanowires using molten gallium and silane plasma

We report the first ever demonstration of using silane directly in the gas phase and molten gallium in a microwave plasma for bulk nucleation and growth of single-crystal quality silicon nanowires. Multiple nanowires nucleated and grew from micron- to millimetre-sized gallium droplets. The resulting nanowires were tens to hundreds of nanometres in diameter and were tens to hundreds of microns long. Transmission electron microscopy results confirmed the nanowires to be single crystalline, devoid of structural defects, and grown along the (100) direction. The as-synthesized silicon nanowires were sheathed with an ultrathin (< 1 nm) non-uniform native oxide amorphous layer that could be directly used in the assembly of electronic and optoelectronic devices.