Electron Field Emission from Carbon Nanotubes

Abstract

Summary form only given. The ubiquitous CRT is finally being overtaken in terms of volume production by flat panel technologies, predominantly based on liquid crystals. It has taken over 30 years for the first LCD based displays to be established, and, at present, to dominate the market. Field emission (FE) based displays are currently at a turning point in establishing a toehold in the hugely competitive market. Carbon nanotubes (CNT) have played a major role in attracting research and development into the FED sector. There has been sustained research into the electron field emission properties of carbon nanotubes (CNT), usually performed on non-aligned random mats, vertically aligned mats, and ordered arrays of CNT on various substrates. In this paper we will introduce some of the key parameters that need be optimised in the design of the cathodes, the definitions used for enhancement factors, and how the location of the anode electrode plays a major role for the correct interpretation of results between different groups. We will also show the importance of nanoscale design over large area for producing FE displays, and how the low temperature growth of CNT structures allows for a step change in the development of these devices. Other routes to producing large area mats of cathodes will also be discussed together with characterisation methodologies for the cathodes. Within the paper we will also present a review of our recent research in the study of the geometric enhancement factor of individual CNT by means of computer simulations. This also leads to an alternative definition of the applied electric field, and enhancement factor. The conclusions drawn from the simulations are backed by experimental field emission from individual CNT, in both two and three terminal configurations to offer further understanding of the mechanism in which these structures operate