Simple Catalyst-Free Method to the Synthesis of β-SiC Nanowires and Their Field Emission Properties

SIC nanowires have been fabricated by a simple catalyst-free method using detonation soot powders and silicon wafers. We characterize their microstructures by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The results show that the nanowires consist of single-crystalline beta phase SIC cores with diameters of 30-100 nm and lengths of 0.5-1.5 mu m wrapped with a very thin amorphous oxide layer. The axial growth direction of each nanowire is preferentially along the K direction, while the low density of planar defects are detected. Unique optical properties are found in the Raman spectroscopy that has a blue shift of about 8 cm(-1) compared to the bulk beta-SiC crystal. Furthermore, field-emission measurements show a relativly low threshold field of 6.2 V mu m(-1), suggesting that it is a promising material for applications in flat panel display. Finally, a possible growth model based on a VS mechanism was proposed to explain the growth of the SIC nanowires.