Some embodiments of vacuum electronics call for nanoscale field-enhancing geometries. Methods and apparatus for using nanoparticles to fabricate nanoscale field-enhancing geometries are described herein. Other embodiments of vacuum electronics call for methods of controlling spacing between a control grid and an electrode on a nano- or micron-scale, and such methods are described herein.

A horizontal multilayer junction-edge field emitter includes a plurality of vertically-stacked multilayer structures separated by isolation layers. Each multilayer structure is configured to produce a 2-dimensional electron gas at a junction between two layers within the structure. The emitter also includes an exposed surface intersecting the 2-dimensional electron gas of each of the plurality of vertically-stacked multilayer structures to form a plurality of effectively one-dimensional horizontal line sources of electron emission.

A cathode of an electron emitting device is described, where the cathode comprises a carbon nanotube (CNT); a nano-filler material; and a carbonizable polymer, and where the cathode exhibits increased hardness, is formed by high temperature thermal treatment, and is devoid of a substrate. Also described is a method of forming a cathode of an electron emitting device, where the method comprises a) forming a dispersed mixture comprising a carbon nanotube, a nano-filler material, and a carbonizable polymer in a solvent; b) coating and/or extruding the mixture; c) drying the coated and/or extruded mixture to remove at least a substantial portion of the solvent; and d) subjecting the dried mixture to a high temperature thermal treatment; where the method results in the cathode of an electron emitting device having increased hardness.

Apparatus and methods are disclosed for a mechanically stable, long-life, cold field emitter assembly which is compatible with ultra-high vacuum and occasional high-temperature flashing. A metal adapter is welded between a hexaboride electrode and a metal filament. Some embodiments use a tungsten filament, a tantalum adapter, and a LaB6 microrod electrode with a nanorod emitter tip. Other material combinations are disclosed, as also usage in electron sources for electron microscopes. In variations, the adapter is deposited onto the filament and the electrode then welded to the adapter.

Apparatus and methods are disclosed for a mechanically stable, long-life junction between hexaboride-containing and tantalum-containing components. Examples are used as a cold field emitter assembly which is compatible with ultra-high vacuum and occasional high-temperature flashing. A metal adapter is welded to a hexaboride electrode. Some embodiments use a tantalum adapter and a LaB6 microrod electrode with a nanorod emitter tip. Other material combinations are disclosed, as also usage in electron sources for electron microscopes. In variations, the adapter is deposited onto a filament and the electrode then welded to the adapter.

A cathode of an electron emitting device is described, where the cathode comprises a carbon nanotube (CNT); a nano-filler material; and a carbonizable polymer; and where the cathode exhibits increased hardness, is formed by high temperature thermal treatment, and is devoid of a substrate. Also described is a method of forming a cathode of an electron emitting device, where the method comprises a) forming a dispersed mixture comprising a carbon nanotube, a nano-filler material, and a carbonizable polymer in a solvent; b) coating and/or extruding the mixture; c) drying the coated and/or extruded mixture to remove at least a substantial portion of the solvent; and d) subjecting the dried mixture to a high temperature thermal treatment; where the method results in the cathode of an electron emitting device having increased hardness.