Abstract: 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.

Abstract: 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 there through. 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.

Abstract: A method for preparing a graphite nanofiber is herein provided, which comprises a raw gases are supplied on the surface of a substrate provided thereon with a catalyst layer for the growth of graphite nanofibers according to the CVD technique, wherein the method is characterized by forming a catalyst layer having a desired thickness and then forming, on the catalyst layer of the substrate, a graphite nanofiber whose overall thickness is controlled and which comprises a graphite nanofiber layer and a non-fibrous layer. The resulting graphite nanofibers can be used in an emitter or a field emission display element. The thickness of the catalyst layer formed on a substrate is controlled by the method and this in turn permits the control of the thickness of the non-fibrous layer formed on the catalyst layer and the control of the thickness of the graphite nanofibers likewise formed on the catalyst layer.