Field emission from vertically aligned carbon nanotubes

Abstract

Carbon nanotubes (CNTs) have a diverse range of applications as a result of their high surface area, high strength, and very unique electronic properties and this thesis studied the electrical characteristics of a triode electron emission device. In particular, the mechanism by which electrons are emitted from the tip of the CNT was investigated. A finite element analysis package, FlexPDE3 ©, was used for electrostatic modeling of the particular triode geometry. From these simulations, it was determined that the magnitude of the electric field at the nanotube tip had a linear dependence on the voltage applied to the anode and gate electrodes. These results, coupled with Fowler-Nordheim theory, predicted theoretical results that corresponded very well with experimental results obtained by Mohajerazedah et al.1 Saturation in the emission current was also observed and possible explanations were noted. The diffraction of the electron beam was modeled using Fresnal diffraction theory and some numerical results applying to the particular triode geometry were obtained. Finally, a plausible mechanism for controlling beam diffraction was considered.