Electron emitters and methods of fabricating the electron emitters are disclosed. According to certain embodiments, an electron emitter includes a tip with a planar region having a diameter in a range of approximately (0.05-10) micrometers. The electron emitter tip is configured to release field emission electrons. The electron emitter further includes a work-function-lowering material coated on the tip.

A carbon nanomaterial functionalized needle tip is modified with a low work function material. The needle tip is formed by combining a carbon nanomaterial with a material of a needle tip through a covalent bond. The interior or outer surface of the carbon nanomaterial is modified with a low work function material. The material of the needle tip is a metal which can be any of tungsten, iron, cobalt, nickel, and titanium. The carbon nanomaterial can be carbon nanocone or carbon nanotube. The tip of the carbon nanomaterial has the same orientation as the metal needle tip. The low work function material can be selected from metals, metal carbides, metal oxides, borides, nitrides, and endohedral metallofullerene. The carbon nanomaterial functionalized needle tip has a lower electron emission barrier, and can effectively reduce the electric field intensity required for electron emission, and improve the emission current and emission efficiency.

A compound field emitter (CFE) includes a first surface possessing a field enhancement factor >1, and a second surface possessing one or both of a field enhancement factor >1, or a low work function, wherein the second surface is coated, formed or applied upon the first surface. The second surface has a characteristic size at least 3 times smaller than the first surface, and the outer surface includes a coating of calcium aluminate 12CaO-7Al2O3.

Electron emitters and method of fabricating the electron emitters are disclosed. According to certain embodiments, an electron emitter includes a tip with a planar region having a diameter in a range of approximately (0.05-10) micrometers. The electron emitter tip is configured to release field emission electrons. The electron emitter further includes a work-function-lowering material coated on the tip.

The present disclosure provides a method of manufacturing an electron source. The method includes forming one or more fixed emission sites on at least one needle tip, the fixed emission sites including a reaction product formed by metal atoms on a surface of the needle tip and gas molecules.

Electron emitters and methods of fabricating the electron emitters are disclosed. According to certain embodiments, an electron emitter includes a tip with a planar region having a diameter in a range of approximately (0.05-10) micrometers. The electron emitter tip is configured to release field emission electrons. The electron emitter further includes a work-function-lowering material coated on the tip.

A compound field emitter (CFE) includes a first surface possessing a field enhancement factor >1, and a second surface possessing one or both of a field enhancement factor >1, or a low work function, wherein the second surface is coated, formed or applied upon the first surface. The second surface has a characteristic size at least 3 times smaller than the first surface, and the outer surface includes a coating of calcium aluminate 12CaO-7Al2O3.

The present disclosure provides a method of regenerating an electron source, the electron source including at least one emission site fixed on a needle tip, and the emission site including a reaction product formed by metal atoms and gas molecules. The method includes regenerating the electron source in situ if an emission capability of the electron source satisfies a regeneration condition.

The present disclosure provides an electron source, including one or more tips, wherein at least one of the tips comprises one or more fixed emission sites, wherein at least one of the tips includes one or more fixed emission sites, wherein the emission sites includes a reaction product of metal atoms on a surface of the tip with gas molecules.

A device for controlling electron flow is provided. The device comprises a cathode, an elongate electrical conductor embedded in a diamond substrate, an anode, and a control electrode provided on the substrate surface for modifying the electric field in the region of the end of the conductor. A method of manufacturing the device is also provided.