Planar field emitters and high efficiency photocathodes based on ultrananocrystalline diamond

A method of forming a photocathode, comprising:

• disposing a first layer on a substrate;
• seeding the first layer with nanodiamond particles;
• maintaining the substrate with the seeded first layer disposed thereon at a first temperature and a first pressure in a mixture of gases, the mixture including nitrogen;
• exposing the first layer to a microwave plasma to form a nitrogen doped ultrananocrystalline diamond film on the first layer, the nitrogen doped ultrananocrystalline diamond film having a percentage of nitrogen in the range of about 0.05 atom % to about 0.5 atom %;
• maintaining the nitrogen doped ultrananocrystalline diamond film at a second temperature and second pressure in hydrogen gas;
• and
• exposing the nitrogen doped ultrananocrystalline diamond film to a microwave plasma to hydrogen terminate the nitrogen doped ultrananocrystalline diamond film.

A field emitter, comprising:

• a planar substrate;
• a first layer disposed on the planar substrate;
• and
• a nitrogen doped ultrananocrystalline diamond film disposed on the first layer, the nitrogen doped ultrananocrystalline diamond film having a percentage of nitrogen in the range of about 0.05 atom % to about 0.5 atom %,
• wherein, the field emitter has about 1012 to about 1014 emitting sites per cm2.

A photocathode, comprising:

• a substrate;
• a first layer disposed on the substrate;
• and
• a hydrogen terminated nitrogen doped ultrananocrystalline diamond film disposed on the first layer, the hydrogen terminated nitrogen doped ultrananocrystalline diamond film having a percentage of nitrogen in the range of about 0.05 atom % to about 0.5 atom %,
• wherein, the photocathode has about 1012 to about 1014 emitting sites per cm2.