Theory of Carbon Nanotube (CNT)-Based Electron Field Emitters

Abstract

Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs) are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules.

Operational characteristics of a graphene-based electron field emitter

“…Specifically, the theoretical description of the physical effects that are manifested in CNT-based cathodes and that govern their emission characteristics is presented in the recently published Ref. 9. Such cathodes are used in applications such as flat monitors, 10-12 miniature x-ray sources, [13][14][15][16][17][18][19][20][21] cathode ray lighting tubes, 4,22-26 microwave radiation generators and amplifiers in satellite telecommunication systems.…”

“…[1][2][3][4][5][6][7][8][9] The advantages of such sources relate mainly to the good conductivity of carbon nanostructures and their nanoscale sizes, which provide multifold amplification of the electric field near the edges of the material. This permits the realization of a considerable emission current at a relatively low applied voltage, which offers the opportunity to considerably reduce the weight and size of many vacuum electronics devices.…”

Field Emitters Using Inverse Opal Structures

“…Electron field emission is the process of extracting electrons from the surface of a solid under an electric field. The emitted electrons can be used for a number of important applications including field emission displays, X‐ray spectroscopy sources, harsh environment electronics, and high‐speed electronics . The combination of ballistic conduction through a vacuum channel, the inherently fast emission process, and the ability to operate at high temperatures has made field emission a topic of intense interest for two decades .…”

Стабильность Полевой Эмиссии Одиночной Углеродной Нанотрубки

“…Широкие перспективы применения полевой эмиссии (ПЭ) требуют детального изучения этого явления, в первую очередь с точки зрения получения высоких плотностей тока эмиссии и стабильности этого про-цесса [16,17]. Вольт-амперная характеристика холод-ного катода на участке преобладания тока полевой эмиссии, как правило, описывается формулой Фаулера-Нордгейма.…”