Chapter 28 - Field Electron Emissions from Carbon Nanotubes

Abstract

This chapter describes the emission characteristics of various carbon nanotubes (CNTs). It reviews the recent observations of the pentagonal rings within a CNT cap. The present state of the development of the CNT-based field emission displays (FEDs) is also described. The carbon nanotubes (CNTs) possess some properties which are favorable for the field emitters. These properties include: the needle-like shape with a sharp tip, the high chemical stability, the high mechanical strength, the low carbon atom mobility, and the good electrical conductivity. In the field emission microscopy (FEM), the regions where the electrons are emitted from the CNTs are imaged at high magnification as bright spots on the anode screen. Therefore, by placing the probe hole of the screen within one of the bright spots, emission currents from a single nanotube can be measured. The open-ended multi-wall nanotubes (MWNTs) begin to emit electrons at the lowest tip voltage and sustain the highest current density. Nanografibers grown in hydrogen give higher currents than ordinary MWNTs.