Abstract: In accordance with the invention, a microwave vacuum tube device, such as a traveling wave tube, is provided with an electron source comprising activated ultrafine diamonds. Applicants have discovered that ultrafine diamonds (5-1,000 nm diameter), when activated by heat treatment in a hydrogen plasma, become excellent room-temperature electron emitters capable of producing electron emission current density of at least 10 mA/cm.sup.2 at low electric fields of 10 V/micrometer. Sources using these diamonds provide electrons for microwave vacuum tubes at low voltage, low operating temperature and with fast turn-on characteristics. A multiple grid structure is described for providing high quality electron beams particularly useful for traveling wave tubes.

Abstract: A novel and advantageous cathode structure for a field emission display apparatus is disclosed. A given pixel comprises a multiplicity of spaced apart emitter bodies on a support. A given emitter body comprises diamond and/or rare earth boride, and has a relatively sharp geometrical feature that facilitates electron emission from the emitter body. By way of example, the emitter body comprises diamond bodies grown on a support, or it comprises a pre-existing diamond particle that was placed on the support. Such emitter bodies generally can be provided easily and at low cost, and typically have naturally occurring sharp geometrical features such as points and edges. We have also discovered that appropriately grown rare earth boride films of thickness 30 nm or less may substantially improve electron emission from emitter bodies, and some preferred embodiments of the invention comprise a cathode structure that comprises a thin layer of, e.g., LaB.sub.6 on the emitter bodies.

Abstract: Applicants have discovered methods for making, treating and using diamonds which substantially enhance their capability for low voltage emission. Specifically, applicants have discovered that defect-rich diamonds--diamonds grown or treated to increase the concentration of defects--have enhanced properties of low voltage emission. Defect-rich diamonds are characterized in Raman spectroscopy by a diamond peak at 1332 cm.sup.-1 broadened by a full width at half maximum .DELTA.K in the range 5-15 cm.sup.-1 (and preferably 7-11 cm.sup.-1). Such defect-rich diamonds can emit electron current densities of 0.1 mA/mm.sup.2 or more at a low applied field of 25 V/.mu.m or less. Particularly advantageous structures use such diamonds in an array of islands or particles each less than 10 .mu.m in diameter at fields of 15 V/.mu.m or less.

Abstract: Improved plasma displays utilize permanent magnet components for low-voltage operation. Permanent magnet components providing magnetic fields transverse to the direction of electron movement increase the electron pathlength, thereby enhancing the ionization efficiency of the electrons. This permits lower voltage operation, higher-pixel density and greater durability. In exemplary embodiments, magnetic components can be placed below the cathode, disposed between the electrodes, or incorporated in the cathode.

Abstract: Applicants have discovered methods for making electron emitters using commercially available diamond particles treated to enhance their capability for electron emission under extremely low electric fields. Specifically, applicants have discovered that electron emitters comprising ultra-fine (5-10,000 nm) diamond particles heat-treated by a hydrogen plasma, can produce electron emission current density of at least 0.1 mA/mm.sup.2 at extremely low electric fields of 0.5-1.5 V/.mu.m. These field values are about an order of magnitude lower than exhibited by the best defective CVD diamond and almost two orders of magnitude lower than p-type semiconducting diamond. Emitters are preferably fabricated by suspending the ultra-fine diamond particles, preferably in the nanometer size range, in an aqueous solution, applying the suspension as a coating onto a conducting substrate such as n-type Si or metal, and then subjecting the coated substrate to a plasma of hydrogen, preferably at temperatures above 300.degree. C.

Abstract: The pillar structure according to the invention has a substantially longer surface path length from negative to positive electrodes resist breakdown in a high voltage environment. The processing and assembly methods in this invention permit low-cost manufacturing of high breakdown-voltage, dielectric pillars for the flat panel display.

Abstract: In accordance with the invention, a field emission device is made by disposing emitter material on an insulating substrate, applying masking particles to the emitter material, applying an insulating film and a gate conductor film over the masking particles and emitter material and removing the particles to reveal a random distribution of apertures to the emitter material. The result is a novel and economical field emission device having numerous randomly distributed emission apertures which can be used to make low cost flat panel displays.

Abstract: In accordance with the invention, a field emission device is provided with an improved pillar structure comprising multi-layer pillars. The pillars have a geometric structure that traps most secondary electrons and an exposed surface that reduces the number of secondary electrons. Processing and assembly methods permit low-cost manufacturing of high breakdown-voltage devices, including flat panel displays.

Abstract: In accordance with the invention, a field emission device is made by disposing emitter material on an insulating substrate, applying a sacrificial film to the emitter material and forming over the sacrificial layer a conductive gate layer having a random distribution of apertures therein. In the preferred process, the gate is formed by applying masking particles to the sacrificial film, applying a conductive film over the masking particles and the sacrificial film and then removing the masking particles to reveal a random distribution of apertures. The sacrificial film is then removed. The apertures then extend to the emitter material. In a preferred embodiment, the sacrificial film contains dielectric spacer particles which remain after the film is removed to separate the emitter from the gate. The result is a novel and economical field emission device having numerous randomly distributed emission apertures which can be used to make low cost flat panel displays.

Abstract: The present invention provides improved methods for making field emission devices by which one can pre-deposit and bond the diamond particles or islands on a flexible metal foil at a desirably high temperature (e.g., near 900.degree. C. or higher), and then subsequently attach the high-quality- emitter-coated conductor foil onto the glass substrate. In addition to maximizing the field emitter properties, these methods provide high-speed, low-cost manufacturing. Since the field emitters can be pre-deposited on the metal foil in the form of long continuous sheet wound as a roll, the cathode assembly can be made by a high-speed, automated bonding process without having to subject each of the emitter-coated glass substrates to plasma heat treatment in a vacuum chamber.