Hughes Aircraft Company

The United States of America As Represented by the Administrator of the

Other

The United States of America As Represented by the Administrator

Ralph Forman

Robert T Longo

Arthur E Manoly

Zaher Bardai

Randy K Rolph

Mario A Barillas

James S Sovey

Edwin G Wintucky

Arthur N Curren

Ben T Ebihara

Arlene E Lamb

Outgassed materials liberated in spaces between pointed field emitter tips and an electrode structure during electrical operation of a field emitter device are vented through passageways to a pump or gettering material provided in a separate space. The passageways may include channels formed through an insulating layer between a base for the field emitters, and the electrode structure, with the channels interconnecting adjacent spaces in a row direction. Where the electrode structure includes a gate electrode layer and an anode layer, similar channels may be formed through an insulator layer provided therebetween. The field emitters may be formed in an arrangement of rows and columns, with the spacing between the columns smaller than the spacing between the rows. Holes are formed by anisotropic etching through the anode, gate electrode, and insulator layers down to the base. Subsequent isotropic etching of the insulator layers through the holes in the anode and gate electrode layers is controlled to cause sufficient undercutting in the insulator layers that adjacent holes merge together only in the row direction to form the channels.

Field emitter structure and fabrication process providing passageways

A low work function surface for a dispenser cathode structure. The cathode structure comprising a heater and an electron emitting surface substrate or core composed of a porous tungsten matrix impregnated with a barium containing impregnant distributed therethrough. The structure is made by a method in which a nanometer thick layer of scandium oxide is sputtered onto the outermost surface of the impregnated tungsten core, or substrate, and then oxidized by exposing the sputtered scandium oxide surface layer to an oxygen atmosphere. The oxidized surface layer is activated by turning on the heater, for example, to cause the release of a small portion of the barium in the barium-containing impregnant. Some of the released barium migrates into the scandium oxide surface layer to form a monolayer of barium oxide on at least a portion thereof.

Sputtered scandate coatings for dispenser cathodes

Outgassed materials liberated in spaces between pointed field emitter tips and an electrode structure during electrical operation of a field emitter device are vented through passageways to a pump of gettering material provided in a separate space. The passageways may include channels formed through an insulating layer between a base for the field emitters, and the electrode structure, with the channels interconnecting adjacent spaces in a row direction. Where the electrode structure includes a gate electrode layer and an anode layer, similar channels may be formed through an insulator layer provided therebetween. The field emitters may be formed in an arrangement of rows and columns, with the spacing between the columns smaller than the spacing between the rows.

Field emitter structure providing passageways for venting of outgassed

Sputtered scandate coatings for dispenser cathodes and methods for

A plurality of field emitters in the form of hollow, upstanding pointed cones or pyramids formed by a molding process extend from a surface of an electrically conductive layer. An electrically conductive mesh is adhered to an opposite surface of the conductive layer by a high temperature brazing process in electrical connection with the conductive layer. The mesh provides a strong metal base with good thermal conductivity for mounting. Additional elements such as a gate and anode structure may be formed on the conductive layer in alignment with the field emitters to form a field emitting triode array or the like.

Field emitter structure and fabrication process

Conical field emitter elements are formed on a surface of a substrate after which a layer of metal is deposited on top of the substrate surface and over the field emitter elements. A layer of oxide is then deposited over the metal layer. Another layer of metal is deposited over the layer of oxide to form a gate metal layer. A layer of photoresist is then deposited over the gate metal layer. The layer of photoresist is then plasma etched in an oxygen atmosphere to cause portions of the photoresist above respective field emitter elements to be removed and provide self-aligned holes in the photoresist over each of the field emitter elements. The size of the holes may be controlled by appropriately controlling process parameter, including plasma etching time and power and/or initial photoresist thickness. The exposed gate metal layer is etched using the layer of photoresist as a mask. The photoresist layer is removed, and the layer of oxide is etched to expose the field emitter elements. Another oxide layer and an anode metal layer also may be formed over the gate metal layer to produce a self-aligned triode structure.

Self-aligned gate process for fabricating field emitter arrays

A field emission cathode 12 is positioned in a pair of intersecting cross grooves 30, 32 in the end of a ceramic tube 14 by a metal end cap 24. A spring 34 in electrical contact with the base of the cathode provides the necessary pressure to maintain continuous circumferential electrical contact between the gate film and a raised edge 38 on the end cap. With this structure the cathode chip is self-centering and easily replaceable. Also the gate film of the cathode is not abraded or rubbed during installation, and the holder is readily degassed.

Apparatus for mounting a field emission cathode

A specially textured surface of pyrolytic graphite exhibits extremely low yields of secondary electrons and reduced numbers of reflected primary electrons after impingement of high energy primary electrons. Electrode plates of this material are used in multistage depressed collectors. An ion flux having an energy between 500 eV and 1000 eV and a current density between 1.0 mA/cm.sup.2 and 6.0 mA/cm.sup.2 produces surface roughening or texturing which is in the form of needles or spires. Such textured surfaces are especially useful as anode collector plates in high efficiency electron tube devices.

Ion sputter textured graphite electrode plates

A specially textured surface of pyrolytic graphite exhibits extremely low yields of secondary electrons and reduced numbers of reflected primary electrons after impingement of high energy primary electrons. An ion flux having an energy between 500 eV and 1000 eV and a current density between 1.0 mA/cm.sup.2 and 6.0 mA/cm.sup.2 produces surface roughening or texturing which is in the form of needles or spines. Such textured surfaces are especially useful as anode collector plates in high efficiency electron tube devices.

Growing community of inventors

Rocky River, OH, United States of America

Ralph Forman