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Abstract

The subject is a field emission cold cathode element having a conducting substrate, a dielectric layer which is on the substrate and has holes, emitter electrodes which have a sharp-pointed tip and stand on the substrate in the respective holes in the dielectric layer and a gate electrode layer which is on the dielectric layer and has apertures right above the respective holes in the dielectric layer. The tip of each emitter electrode is near or in the aperture in the gate electrode layer, and the emission current depends on the position of the emitter tip relative to the gate electrode. According to the invention, the gate electrode layer is made relatively thick in limited regions surrounding the respective apertures and relatively thin in other regions to compensate for inevitable variations in the emitter electrode heights without augmenting interlayer stresses attributed to different thermal expansions of the gate electrode and dielectric layers. A preferred way to locally thicken the gate electrode is to overlay a relatively thin electrode layer with a supplementary electrode layer only in the aforementioned limited regions, and a refractory material can be used for the supplementary layer.

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First Claim