Field-emission type cold cathode and application thereof

1. Field of the Invention A field-emission type cold cathode is disclosed, by which the degradation of the withstand voltage between the gate electrode and emitter and discharge destruction are suppressed, and the operating voltage and the distance between the gate electrode and emitter can be reduced. The cold cathode comprises a substrate (on a surface of which an emitter is formed) for functioning as a leading emitter electrode; and a gate electrode, formed via an insulating film on the substrate, having an aperture which surrounds the emitter via a space. The height of a boundary (which faces the space) between the insulating film and the substrate is lower than the height of the surface of the substrate on which the emitter is formed. An insulated trench surrounds the area on which the emitter is formed, where the above boundary is placed between the emitter and the trench, and a part of the insulating film is present between the boundary and the trench.