Field Emission Stability of Anodic Aluminum Oxide Carbon Nanotube Field Emitter in the Triode Structure

Abstract

In this work, fabricated field emission (FE) triode arrays with the anodic aluminum oxide (AAO) template carbon nanotube (CNTs) as the field emitters are numerically analyzed. To obtain physically sound self-consistent solution, a set of Maxwell's equations coupling with Lorentz equation are solved simultaneously using a finite difference time domain particle-in-cell method. The FE current is then computed with the Fowler-Nordheim equation. To validate the simulation model, we firstly calibrate the collected electron current density between the measured AAO-CNTs and calculated result. The FE current is dominated by, such as density, height, diameter, and tilt angle of CNTs, and applied bias, respectively. A high density of CNTs will result in strong screening effect among adjacent CNTs and reduce the magnitude of electric field. Consequently, it significantly affects the emitted and collected electron current densities. However, the structure with much higher density of CNTs obviously emits more stable current than that of a low density of CNTs. There is an optimal setting on the height and diameter of the CNTs within the explored structure which exhibits the highest current density. When we vary the density of CNTs, the structure with high density (say the number of CNTs is greater than 30) shows the most stable and smallest fluctuation on the current density against the randomly generated samples of the height and tilt angle of CNTs.