Catalyst-free and controllable growth of SiC_xN_y nanorods

Non vapor-liquid-solid (VLS) method of growing high-purity silicon carbon nitride (SiC_xN_y) nanorods with rod widths ranging from 10 to 60 nm and lengths of microns is reported. Unlike the case for the ordinary VLS or catalyst-mediated growth, the two-stage process presented here is a catalyst-free approach since it does not involve any catalyst during the growth of the nanorods. The first stage involves formation of a buffer layer containing various densities of SiC_xN_y nanocrystals by electron cyclotron resonance plasma enhanced chemical vapor deposition (PECVD); whereas the second stage involves a high growth rate along a preferred orientation to produce high-aspect-ratio nanorods using microwave PECVD. Moreover, the number density and the diameter of the nanorods can be controlled by the number density and the size of the nanocrystals in the buffer layer. Production of quasi-aligned SiC_xN_y nanorods with a number density of the rods as hi gh as 10¹⁰ cm^-2 has been achieved. The SiC_xN_y nanorods thus produced exhibit good field emission characteristics with stable operation over 8 h. The approach presented here provides a new advance to synthesize nanorod materials in a controllable manner.