Context

This post provides access to a literature review that I completed as coursework for the final year of my undergraduate physics degree. The subject I chose, from those available, was ‘Nanostructured cold cathode electron emitters’. My motivation was that free electrons are obviously incredibly important to many fields of experimental physics and, in the past, formed the backbone of consumer electronic devices, and I wanted to know more about the electron emission techniques of the future. As it is, I’m not sure I achieved that, but I did get a much better picture of the gritty details of cutting-edge physics, and what can happen when the industrial aspirations are pulled from under a developing technology.

Figure 2.3 from the paper. Scanning electron micrographs of four commercially used electron emitters. (a) (top two panels) shows a tungsten thermionic cathode. (b) (left two panels) shows two lanthanum hexaboride thermionic cathodes. (c) shows a zirconia-coated-tungsten Schottky emitter. (d) shows a cold cathode tungsten field emitter.

Abstract

Field emission is the phenomenon whereby electrons tunnel through a material’s surface potential barrier if subjected to a large electric field. Devices based on this principle have potential as electron sources that are smaller, faster and more efficient than thermionic emitters, and that can operate at room temperature. In this paper, we review the historical development of field emitters, their inherent benefits and drawbacks, the applications for which field emission would be most appropriate, and the challenges still to overcome.

Download PDF

This paper contains a lot of figures reproduced from other authors. I have endeavoured to obtain permission via the proper portals for each publisher, but if you think I have missed anything please get in touch.