Chemically Stable Visible Light Photoemission Electron Source

Abstract

A method of producing electrons via photoemission comprising providing diamond, treating a surface of the diamond by exposing it to atomic hydrogen inside an ultrahigh vacuum chamber, illuminating the surface with photons, and extracting the photoemitted electons. A chemically stable visible light photoemission electron source comprising a diamond film having a surface terminated with hydrogen and a light source.

What we claim is: 
     
         1 . A method of producing electrons via photoemission comprising:
 providing diamond;   treating a surface of the diamond by exposing it to hydrogen inside an ultrahigh vacuum chamber; and   illuminating the surface with photons from light having a wavelength similar to 405 nm and thereby photoemitting electrons.   
     
     
         2 . The method of producing electrons via photoemission of  claim 1  wherein the diamond substrate is doped p-type with boron and results in the diamond being conductive. 
     
     
         3 . The method of producing electrons via photoemission of  claim 1  wherein the treating a surface of the diamond by exposing it to hydrogen inside an ultrahigh vacuum chamber comprises utilizing a tungsten tube to cause low energy photoemission. 
     
     
         4 . The method of producing electrons via photoemission of  claim 1  wherein the treating a surface of the diamond by exposing it to hydrogen inside an ultrahigh vacuum chamber comprises utilizing a tungsten tube heated to about 1800° C. 
     
     
         5 . The method of producing electrons via photoemission of  claim 1  wherein the treating a surface of the diamond by exposing it to hydrogen inside an ultrahigh vacuum chamber comprises utilizing a tungsten tube heated to about 1800° C. with hydrogen passing through it. 
     
     
         6 . The method of producing electrons via photoemission of  claim 1  wherein the treating a surface of the diamond by exposing it to hydrogen inside an ultrahigh vacuum chamber comprises utilizing a tungsten tube wherein the tungsten tube is oriented with the tube axis aimed at the diamond surface and a short distance from the diamond surface to cause low energy photoemission. 
     
     
         7 . The method of producing electrons via photoemission of  claim 1  wherein the diamond does not comprise grain boundaries. 
     
     
         8 . The method of producing electrons via photoemission of  claim 1  wherein the hydrogen exposure is performed inside the same vacuum chamber as photoemission, and can be performed repeatedly before, during, or after the photoemission. 
     
     
         9 . A chemically stable visible light photoemission electron source comprising:
 a diamond film having a surface terminated with hydrogen; and   a light source having a wavelength of from about 475 nm to about 250 nm;   wherein electrons are generated at the surface of the diamond and photoemitted.   
     
     
         10 . The chemically stable visible light photoemission electron source of  claim 9  wherein the diamond film has a top surface and a bottom surface, wherein the top surface is exposed to hydrogen and wherein the light source is located near, or the light is directed to, the bottom surface such that the illumination travels through the diamond. 
     
     
         11 . The chemically stable visible light photoemission electron source of  claim 9  wherein the electrons move directly from the surface into a vacuum without first being excited into the conduction band. 
     
     
         12 . The chemically stable visible light photoemission electron source of  claim 9  wherein the light source has a wavelength of about 405 nm or less. 
     
     
         13 . The chemically stable visible light photoemission electron source of  claim 9  wherein the light source has a wavelength of 475 nm or less or is one selected from the group consisting of 450 nm, 405 nm, 375 nm and 354 nm. 
     
     
         14 . The chemically stable visible light photoemission electron source of  claim 9  wherein the temperature of the diamond film is increased in order to improve the quantum efficiency of emission. 
     
     
         15 . The chemically stable visible light photoemission electron source of  claim 9  wherein the temperature of the diamond film is changed in order to change the lowest energy of emitted electrons according to the change in the diamond band gap energy. 
     
     
         16 . The chemically stable visible light photoemission electron source of  claim 9  wherein the diamond is exposed to hydrogen during emission in order to improve the quantum efficiency of emission. 
     
     
         17 . The chemically stable visible light photoemission electron source of  claim 9  wherein the diamond is exposed to ultraviolet light created by hydrogen instead of or in addition to other light sources in order to cause emission.