Crack-Assisted Field Emission Enhancement of Carbon Nanotube Films for Vacuum Electronics
Carbon nanotube (CNT) has been considered to be an ideal cathode candidate for field emission applications since 1995, and there is always a trade-off between the number of emission tips and the field screening effect to achieve a high field emission performance. In this study, CNT cathode films with spontaneously formed cracks are fabricated by a simple vacuum filtration process at room temperature without caring about the alignment of CNTs, and the crack feature can be controlled with CNT concentration. The crack-assisted field emission devices display greatly enhanced performance and the best is achieved with pretty low turn-on field of 0.40 V/μm and threshold field of 0.55 V/μm, a recorded high field enhancement factor of 43000, and excellent field emission stability. This outstanding performance due to simultaneous increase of the emission tips and reduction of the field screening effect demonstrates the crack-assisted CNT film can be a promising candidate for field emission applications.