Influence of cathode material on emission characteristics of field emitters for microelectronics devices

Abstract

In order to find out the cathode material suitable to vacuum microelectronics devices, dependence of cathode material of field emitters was investigated with respect to the emission characteristics. Since the field emitters for vacuum microelectronics devices are fabricated by thin film processes, the characteristics of the electron emission from deposited materials should be examined. In the present study, a dozen materials were deposited onto the tungsten needle fabricated by well-controlled electrochemical etching. Measurement of the emission was performed at the pressure of 10−9 Torr range. The current–voltage characteristics and the stability measurements revealed that the gold emitters indicated excellent properties: stable and high current at low extraction voltage. The effective surface work function and the effective emission area were evaluated from the Fowler–Nordheim theory, assuming that the emission area rapidly decreases with reducing the apex radius. From this analysis, it is clarified that the gold emitter had the lowest effective work function among the examined emitters. The results can be interpreted as that in order to obtain stable emission characteristics, materials with inert surface should be selected.