Superior CoO/SiC nanowire field emitters with substantially increased stable emission sites: ultralow turn-on field, high current density and high stability

Abstract

The ultralow turn-on fields, high current density and high emission stability of field emission (FE) cathodes are described as three of the main factors promoting their practical application in electronic devices, despite the fact that integrating all of these elements into a single cathode is a big challenge. In this study, we explored high-performance FE cathodes with numerous pyramid-shaped CoO nanoparticles around single-crystal N-doped SiC nanowires based on a novel and facile gas-phase in situ cation exchange (CA) method. The CoO nanoparticles growing from the wires' surface significantly increased electron emission sites. The strong connection between the wire body and the nanoparticles without interfaces provided emitters with a robust structure to prevent structural damage in long-term FE operation. In addition, the as-constructed CoO/SiC heterojunction and incorporated N dopants offered emitters with low work function (Φ) for electron emission. Accordingly, the obtained CoO/SiC nanowire field emitters presented superior comprehensive performance with ultralow turn-on field (0.40 V μm⁻¹), high current density (18.6 mA cm⁻²) and high emission stability with just ±2% current fluctuation during 10 h long-term operation. The ultralow turn-on field could be comparable to the state-of-the-art one ever reported. This study offers a new approach to the design and fabrication of improved FE cathodes for additional prospective applications in harsh working environments requiring high performance.