Field Emission and Application of Carbon Nanotubes

Abstract

The mechanism of field emission from a metal surface was well explained based on the quantum mechanics in early 20th century. Since then, various materials have been studied for field emitters. However, so far, we have been using only limited materials as a field emitter and an application in some area requires further scientific understandings and technological advancements. In this paper, we review the current status of researches in field emission and emission phenomena of carbon nanotubes (CNTs). This may include current saturation induced by gas adsorbates, screening effects, high current emission, degradation of emitter, and field enhancement factor. We also introduce the present status in the development of various CNT-based field emission devices and discuss their performances. In this part, various potential applications such as field emission display, ionization gauge, X-ray gun, and lamp will be presented. Keywords: Carbon nanotubes; field emission. 69 NANO 2007.02:69-89. Downloaded from www.worldscientific.com by NORTHWESTERN UNIVERSITY on 03/25/15. For personal use only. 70 S. C. Lim et al. NANO 2007.02:69-89. Downloaded from www.worldscientific.com by NORTHWESTERN UNIVERSITY on 03/25/15. For personal use only. Field Emission and Application of Carbon Nanotubes 71 NANO 2007.02:69-89. Downloaded from www.worldscientific.com by NORTHWESTERN UNIVERSITY on 03/25/15. For personal use only. 72 S. C. Lim et al.

Development of durable carbon field emission nanostructures for vacuum electronics

“…Additionally the effect of mutual shielding of neighboring nanotubes in the array also reduces the average current density which is confirmed by [5]. There was no observed of criticality of CPEC relative to the influence of residual gases that is typical for of CNTs [1]. Thus, in the experimental samples of CPES current density of 0.2 A·cm 2-and longevity of the emitter at least 2000 hours were achieved.…”

“…Carbon nanotubes (CNTs) and diamond-like carbon (DLC) are promising structures with unique field emission possibilities [1,2]. Despite the fact that the threshold of the emission current of single wall CNT is indicated as a few decades of μA, corresponding to 10 5 A/cm 2 , in practical applications the average (effective) current density is by many orders of lower.…”

“…The potential applications of field emission structures for use in a variety of vacuum devices (displays, microwave amplifiers and generators) are determined namely by level of current density. It is also important factors affecting the success when creating new devices are short lifetime at high current density, instability under high voltage, poor emission uniformity [3], high transverse velocities of electrons [4], criticality with respect to the composition of residual gases of technical vacuum [1].…”

Morphological Dependence of Field Emission Properties of Silicon Nanowire Arrays

“…The unique sp 3 -bonded crystal structure and the low work function of SiNWs show it to be a potential candidate to be employed as a cold cathode material for¯eld emission device applications. 7,8 Over past few years, many other nanomaterials, such as aligned carbon nanotubes, 10 ultra-nanocrystalline diamond lms, [11][12][13] arrays of gallium nitride nanorods, 14 titanium dioxide nanotubes, 15 cone-shaped zinc oxide nanostructures, 16 tin oxide nanotubes 17 and needle-shaped molybdenum trioxide 18 are showing much more e±ciency in¯eld emission with very low turn-on¯eld. Moreover ion implantation, 19 metallic coating 20 and H 2 surface treatment on diamond lms 21 are observed to signi¯cantly enhance the electron¯eld emission (EFE) properties.…”

Stable, high current density carbon nanotube field emission devices

“…Carbon nanotubes (CNTs) have attracted considerable attention in development of devices for applications such as microwave amplifiers, ionization gauges and low-pressure sensors, micro-propulsion, field emission displays, electron guns for electron microscopes and space science, x-ray sources, lighting, and parallel electron-beam lithography [1][2][3][4][5]. Figure 1 shows a schematic of our process flow for fabrication of CNT field emission (FE) devices.…”