Critical Process Of The Preparation Of Lanthanum Hexaboride Field Emitter Array Cathode

Compared with conventional thermal cathode, field emitter arrays (FEAs) cathode have many special advantages, such as room-temperature operation, high current density, low power dissipation, excellent ON/OFF isolation and instant turn-on characteristics. However, there are some important limitations of micro-fabricated FEAs in their emission current and stability. Aiming at those problems, a new type of LaB6-FEA was fabricated in this paper by using unique emitter material and fabricating technique, in order to improve the emission performance of traditional field emission array cathodes.1. The selection of emitter material was analyzed. At present, a lot of materials of field emitting cold cathodes are being developed such as the silicon and molybdenum. However, most of them have some disadvantages including high work function, low reliability and so on. It has been proved that, lanthanum hexaboride (LaB6), with high conductivity, good heat stability and chemical stability, low work function, and active cathode appearance, is an ideal material for field emission array cathodes. Thus in this paper LaB6 was selected as the emitter material.2. The technology of fabricating LaB6-FEA was studied. It was found that, although a LaB6-FEA could been fabricated through traditional semiconductor technology, there were still some issues such as the corrosion of emission tips, the grid's abscission and the instability of the emission current. In order to solve these problems with the emitter structure unchanged, some critical technologies (coating process, annealing process, package and test) were studied and a series of problem-solving methods were proposed, including: fabricating a new compound sacrificial layer to avoid the tip corrosion, adding a Ni-Cr layer to the bottom of tips to enhance tip height and the binding force between the tips and silicon substrate, adding a protective layer with high resistance to improve the emission stability, and annealing to avoid the grid's abscission. Finally, the LaB6-FEA was successfully prepared with out the above-mentioned problems.3. The field emission measurements of fabricated LaB6-FEA were carried out. Two testing method were introduced, including static test mode and dynamic test mode. Furthermore, the corresponding phenomenon and results were analyzed.