Field emission cathode and method of fabricating the same

A method of fabricating a field emission cathode comprising:

• a step for forming a filament by forming a fine metal wire having resistance against high temperatures into the shape of a hairpin;
• a step for joining a tip of a metal having resistance against high temperatures to a vicinity of the top of said filament;
• a step for vaporizing a metal onto the surface of said tip in a vacuum atmosphere where the field can be emitted, at least to a thickness equal to the thickness of the monolayer of atoms, said metal having a work function which is smaller than the work function of the metal forming the tip, and an oxide of said metal having resistance against high temperatures;
• a step for adsorbing oxygen onto the surface of said tip to a thickness equal to the thickness of the monolayer of atoms by introducing a suitable amount of oxygen gas into said vacuum atmosphere;
• a step for evacuating said oxygen gas to establish again the vacuum atmosphere where the field can be emitted;
• and
• a step for heating said tip at a temperature of 1300.degree. to 1500.degree. C. for 10 to 60 seconds.

A method of fabricating a field emission cathode comprising:

• a step for forming a filament by forming a fine metal wire having resistance against high temperatures into the shape of a hairpin;
• a step for joining a tip of a metal having resistance against high temperatures to a vicinity of the top of said filament;
• a step for joining a metal member to said filament, said metal member having a work function which is smaller than the work function of the metal forming said tip, and an oxide of said metal member having resistance against high temperatures;
• and
• a step for heating said tip at a temperature of 860.degree. to 1500.degree. C. in a vacuum atmosphere where the field can be emitted in which is introduced the oxygen gas while maintaining the partial pressure of the oxygen gas to be smaller than 5.times.10.sup.-7 Torr.

A method of fabricating a field emission cathode comprising:

• a step for forming a filament by forming a fine metal wire having resistance against high temperatures into the shape of a hairpin;
• a step for joining a tip of a metal having resistance against high temperatures to a vicinity of the top of said filament;
• a step of immersing said tip in an aqueous solution of a water-soluble compound including a metal and oxygen, said metal having a work function which is smaller than the work function of the metal forming said tip, and an oxide of said metal having resistance against high temperatures;
• and
• a step of heating said tip at a temperature of 1300.degree. to 1500.degree. C. in a vacuum atmosphere to decompose said water-soluble compound so that said metal is formed on the tip.