Metal-Catalyst-Free Synthesis and Characterization of Single-Crystalline Silicon Oxynitride Nanowires

Shuang Xi,Xiaoping Li,Shiyuan Liu,Liangliang Xu,Tielin Shi,Dan Liu,Zirong Tang

doi:10.1155/2012/620475

Abstract

Large quantities of single-crystal silicon oxynitride nanowires with high N concentration have been synthesized directly on silicon substrate at 1200°C without using any metal catalyst. The diameter of these ternary nanowires is ranging from 10 to 180 nm 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.

Highlights

In recent years, silicon oxynitride (SiOxNy) has received considerable attention as an important dielectric material, due to its superior electrical and physical properties [1]
We report the catalyst-free synthesis of bulk single-crystal SiOxNy nanowires with high N concentration
The results are comparable to the optical performance of the most brilliant white beetle scales reported by Vukusic et al, in which around 60% of incident visible-light is reflected [26]

Summary

Introduction

Silicon oxynitride (SiOxNy) has received considerable attention as an important dielectric material, due to its superior electrical and physical properties [1]. A high concentration of nitrogen in SiOxNy is generally desired: by increasing N/O ratio, a higher dielectric constant and refractive index can be obtained [6, 7]. Most of the silicon oxynitride materials studied up to now have a nitrogen concentration less than 15 at.% [8, 9], and primarily are amorphous SiOxNy films. The properties of silicon oxynitride materials with high N concentration remain largely unexplored [10]. We report the catalyst-free synthesis of bulk single-crystal SiOxNy nanowires with high N concentration. The optical properties of the disordered SiOxNy nanowire mat have been studied

Experimental Details

Findings

Result and Discussion

Conclusion