Electronic emitters with dopant gradient

Abstract

Electron emitters and a method of fabricating emitters are disclosed, having a concentration gradient of impurities, such that the highest concentration of impurities is at the apex of the emitters and decreases toward the base of the emitters. The method comprises the steps of doping, patterning, etching, and oxidizing the substrate, thereby forming the emitters having impurity gradients.

1 . A field emission site, comprising: 
 an electron emitter having a base and an apex and defining a decreasing range of widths from said base to said apex;    a dopant in said emitter having a density generally inversely proportional to said range of widths; and    a generally undoped film under said electron emitter.    
   
   
       2 . The field emission site in  claim 1 , wherein said dopant has a concentration generally inversely proportional to said range of widths.  
   
   
       3 . The field emission site in  claim 2 , wherein said generally undoped film is directly under said electron emitter.  
   
   
       4 . A field emission site, comprising: 
 a generally pure substrate; and    a cathode on said substrate having an apex and a base and defining an increasing range of widths from said apex to said base and having a purity generally directly proportional to said range of widths.    
   
   
       5 . A cathode conductor system, comprising: 
 a tip further comprising: 
 an apex, and  
 a base under said apex;  
   a substrate indivisibly extending from said base; and    a dopant in said tip defining a concentration gradient from said apex to said base and further defining a uniform concentration under said base.    
   
   
       6 . The electrode conductor system in  claim 5 , wherein said dopant defines a concentration of generally zero within said substrate.  
   
   
       7 . An electron-source site, comprising: 
 a film having a generally constant first conductivity; and    an emitter over said film, having a base and an apex, and further having a plurality of conductivities including a low conductivity at said base and a high conductivity at said apex.    
   
   
       8 . The electron-source site in  claim 7 , wherein said first conductivity is at most generally equal to said low conductivity.  
   
   
       9 . The electron-source site in  claim 8 , wherein said film is more conductive than resistive.  
   
   
       10 . The electron-source site in  claim 9 , wherein said emitter further comprises a portion between said apex and said base and having a second conductivity between said high conductivity and said low conductivity.