Structural Design of LaB 6 Composite Field Emission Array Cathode

Abstract

In order to improve the operation stability of traditional Spindt field emission array cathode, a novel structure of lanthanum hexaboride (LaB6) composite field emission array cathode is proposed, which includes an amorphous silicon resistance layer, a molybdenum transition layer, and a lanthanum hexaboride emitter layer. The influences of the thickness of the resistive layer, the transition layer, and the emitter layer on the thermal stress field distribution of the cathode are simulated by ANSYS and the results of simulation are verified by experiments. Simulation results show that the thickness of the resistive layer does not affect the distribution of the thermal stress field, but only changes the value of the thermal stress. The maximum thermal stress of the cathode decreases as the thickness of the resistive layer increases. The transition layer can effectively alleviate the thermal stress of the emission layer, and its thickness affects the field distribution of thermal stress. As a result, the optimum parameters are as follows:a-Si layer thickness is 72 nm, Mo layer thickness is 200 nm, and LaB6 layer thickness is 728 nm. The thermal stress test results of the films are consistent with the simulation results, which proves the feasibility of reducing the thermal stress by introducing the transition layer and the resistive layer.