CATHODE SUBSTRATE HAVING CATHODE ELECTRODE LAYER, INSULATOR LAYER, AND GATE ELECTRODE LAYER FORMED THEREON

摘要

A cathode substrate according to the present invention comprises a cathode electrode layer (12), insulator layer (14) and gate electrode layer (15) formed sequentially on a substrate to be processed (11). The insulator layer includes a hole (14a) formed therethrough. A gate aperture (16) is formed through the gate electrode layer. An emitter (E) is then provided at the bottom of the hole (14a). In this case, the gate aperture comprises a plurality of openings (16a), the total area of which is smaller than the area of top opening of the hole in the insulator layer. The openings are arranged densely at a position opposite to the emitter and just above the hole of the insulator layer.