DEVELOPMENT OF GATED TRANSITION METAL NITRIDE FIELD EMITTER ARRAYS

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We have developed a gated niobium nitride field emitter arrays. The fabrication process can be divided into two major processes : fabrication of emitter covered with niobium nitride and fabrication of gate electrode. We adopted the transfer mold technique to fabricate niobium nitride emitter, by which we can fabricate the emitter apex uniformly. A set of 26 circles were transferred to silicon substrate of which surface had been oxidized. Formation of the mold was performed by anisotropic etching with tetramethylammoniumhydroxide. Oxidation of the mold provide an insulating layer between emitter and gate, which was attached by the following process. After removal of silicon mold, we deposited molybdenum gate electrode onto the insulating layer. Gate aperture was formed by etching back method. The fabricated device was installed into a vacuum chamber and was evaluated its electron emission performance in high vacuum. The driving voltage was 14V at the first stage and after occasional discharges, it increased to 20V.Emission was stable except discharges. Emission pattern was observed and we found some portion of the emitted electrons was incident on the gate electrode. Optimizing the fabrication process, we expect further improved emission property.