Fabrication of cone-shaped CNF/SiC-coated Si-nanocone composite structures and their excellent field emission performance

Abstract

Novel cone-shaped carbon nanofiber (CNF)/silicon carbide (SiC)-coated Si-nanocone (Si-NC) composite structures with excellent field emission (FE) performance have been fabricated by a simple microwave plasma chemical vapour deposition process. Transmission electron microscopy analyses reveal that the newly developed cone-shaped composite structures are composed of bamboo-like herringbone CNFs grown vertically on the tips of conical SiC layers with a flat-top Si cone embedded underneath. For this CNF/SiC-coated Si-NC composite array, a ultra-low threshold field of 0.32 V μm⁻¹ (at 10 mA cm⁻²), a large emission current density of 668 mA cm⁻² at 1.05 V μm⁻¹, and a field enhancement factor as high as ∼48 349 are obtained. In addition, the FE lifetime test performed at a large emission current density of 200 mA cm⁻² under an applied field of 1 V μm⁻¹ shows no discernible decay during a period of over 260 minutes. We deduce that this superior FE performance can be attributed to the specific bamboo-like herringbone CNFs with numerous open graphitic edges and a faceted top end, and the conical base SiC/Si structures with sufficient adhesion to the substrate surface. Such a novel structure with promising emission characteristics makes it a potential material for electron field emitters.