A Fitting Model for High Current Density Field Emission Arrays

Abstract

Summary form only given. We have developed a new method for fitting the current-voltage (I-V) characteristics of the field emission arrays (FEAs) that may be operated at high current density. In recent experiments of FEAs, the Fowler-Nordheim (FN) plots show that the experimental results are apart from the conventional FN fits. Based on the past studies, it is taken for granted that the cause of the current saturation by space charge effects can be excluded at these comparatively lower current density levels. In this work, the FN equation is modified with a global effective work function which is an ensemble average of the local effective work function of individual tips. Within the framework of the effective work function approximation, a self-consistent FN equation including the space charge effects of the field emission electrons has been verified by the 2D finite-difference time-domain particle-in-cell simulation and compared with the experiments performed at Stanford Research Institute, giving excellent agreement. The self-consistent model is demonstrated to be a good fit to the I-V characteristics of high current density FEAs. This also indicates that the space charge effects play an essential role in the saturation behavior of FEAs.