Self-aligned, gated bulk molybdenum field emitter arrays

This paper reports the fabrication of bulk molybdenum field emitter arrays with integrated, self-aligned gates. Based on molybdenum deep reactive ion etching, the fabrication process is significantly simplified compared with that of conventional Spindt-type arrays. In the present structures, the distance between the gate and emitter has been precisely controlled by the thickness of SiO2 dielectric layer. In this work, current densities of 84mA/cm2 were produced from a uniform array of 2500 tips covering a total emission area of just 1 mm2, driven at gate-emitter voltages of just 120 V. Compared to diode-type emitters we reported elsewhere [1], the emission current densities increased by 240 times to 33.6nA/tip, owing to the extractor gates. Further scaling down of the pitch to may lead to an increase of the current densities to several A/cm2, which is very promising for high-current cathode applications such as X-ray sources. ? 2016 IEEE.EI1082-10852016-Februar