Abstract: An electron emitter contains a gate layer (38), an underlying dielectric layer (36), an intermediate non-insulating layer (34) situated below the dielectric layer, and a lower non-insulating region (32) situated below the intermediate non-insulating layer. A multiplicity of electron-emissive particles (42) are situated over the non-insulating region at the bottom of an opening (40) extending through the three layers. The ratio of the thickness of the dielectric layer to the thickness of the intermediate non-insulating layer is in the range of 1:1 to 4:1, while the ratio of the mean diameter of the opening to the thickness of the intermediate non-insulating layer is in the range 1:1 to 10:1. The presence of the intermediate non-insulating layer improves the collimation of the beam of electrons emitted from the electron-emissive elements. The electron emitter is manufactured according to a simple, readily controllable process.

Abstract: A gated field-emission structure contains a emitter electrode (46), an overlying electrically insulating layer (48, and one or more electron-emissive elements (52) situated in one or more apertures extending through the insulating layer. A patterned gate electrode (50) through which each electron-emissive element is exposed overlies the insulating layer. Focusing ridges (54) are situated on the insulating layer on opposite sides of the gate electrode. The focusing ridges, which normally extend to a considerably greater height than the gate electrode, cause emitted electrons to converge into a narrow band.