Enhanced field emission from density-controlled SiC nanowires

Silicon carbide (SiC) nanowires were grown directly on Si substrates by thermal evaporation of WO3 and graphite powders at high temperature using NiO catalyst. The densities of the nanowires were controlled by varying the NiO catalyst concentration. The morphology, structure and composition of the nanowires were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, FTIR, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) measurements. The synthesized nanowires were single crystalline β-SiC oriented along the [1 1 1] direction. Based on the experimental results, a possible growth mechanism was explained on the basis of solid–liquid–solid (SLS) growth model. Field emission measurements showed that the emission efficiency was strongly dependent on the density of SiC nanowires. Lowest turn-on field of 1.8 V μm−1 and highest field enhancement factor of 5.9 × 103 was observed for the medium density SiC nanowire sample.