Numerical simulation of field emission efficiency of anodic aluminum oxide carbon nanotube field emitter in the triode structure

In this work, we study the field emission (FE) properties of carbon nanotubes (CNTs) field emitter in the triode structure fabricated with anodic aluminum oxide (AAO) template. To obtain the self-consistent solution, a set of two-dimensional Maxwell's equations coupling with Lorentz equation are solved with a finite difference time domain (FDTD) particle-in-cell (PIC) method. The FE current is then computed with the Fowler-Nordheim equation. Calculated result of the collected current density shows good agreement with the measured data for the fabricated sample. Effect of the height and number of CNTs on the collected electron current density is thus investigated. We find that the explored structure with few number of CNTs exhibit high current density due to insignificant screening effect. The current density is low and approaches to stable current level when the number of CNTs increases. The simulation further predicts that the structure with the height of CNTs = 0.42 μm has a maximum current density. The FE efficiency (i.e., the collected electron current density/the emission current density) versus the number of CNTs is estimated. The explored AAO-CNTs triode structure maintains high FE efficiency (∼95%) with a nonzero gate voltage.