Bulk synthesis of a-SixNyH and a-SixOy straight and coiled nanowires

Abstract

We report the bulk synthesis of hydrogenated, amorphous Si_xN_y and Si_xO_y nanowires using pools of molten gallium as the solvent medium and microwave plasma consisting of silane in nitrogen and silane in oxygen respectively. High densities of multiple nanowires nucleated and grew from molten gallium pools. The resulting nanowires were tens of nanometers in diameter and tens of microns long. Electron energy loss spectroscopy (EELS) and Fourier transform infra-red (FTIR) spectroscopy showed that the silicon nitride nanowires are hydrogenated amorphous silicon nitride (a-Si_xN_yH). The results of energy dispersive X-ray spectroscopy (EDS) yielded N ∶ Si and O ∶ Si ratios less than the stoichiometric composition of silicon nitride (Si₃N₄) and silica (SiO₂). Studies on the chemical stability and refractive index (RI) measurements demonstrate a-Si_xN_yH nanowires are potential candidates for use as etching masks in nanoscale lithography, and as high index materials in optical coatings.