Metal-catalyst-free synthesis and characterization of single-crystalline silicon oxynitride nanowires

Abstract

Large quantities of single-crystal silicon oxynitride nanowires with high N concentration have been synthesized directly on silicon substrate at 1200C without using any metal catalyst. The diameter of these ternary nanowires is ranging from 10 to 180nm with log-normal distribution, and the length of these nanowires varies from a few hundreds of micrometers to several millimeters. A vapor-solid mechanism was proposed to explain the growth of the nanowires. These nanowires are grown to form a disordered mat with an ultrabright white nonspecular appearance. The mat demonstrates highly diffusive reflectivity with the optical reflectivity of around 80 over the whole visible wavelength, which is comparable to the most brilliant white beetle scales found in nature. The whiteness might be resulted from the strong multiscattering of a large fraction of incident light on the disordered nanowire mat. These ultra-bright white nanowires could form as reflecting surface to meet the stringent requirements of bright-white light-emitting-diode lighting for higher optical efficiency. They can also find applications in diverse fields such as sensors, cosmetics, paints, and tooth whitening. © 2012 Shuang Xi et al.