Low work function material

Abstract

A cathode includes a carbon nanotube layer, which is optimized with a low work function material, such as an alkali. The inclusion of the alkali material improves the field emission properties of the carbon nanotube layer.

1 - 4  (cancelled)  
     
     
         5 . An apparatus comprising: 
 a substrate; and    a carbon nanotube layer deposited on the substrate, the carbon nanotube layer including a separate low work function material.    
     
     
         6 . The apparatus as recited in  claim 5 , wherein the low work function material is deposited as a layer onto the carbon nanotube layer.  
     
     
         7 . The apparatus as recited in  claim 5 , wherein the low work function material is doped into the carbon nanotube layer.  
     
     
         8 . The apparatus as recited in  claim 5 , wherein the low work function material is intercalated with the carbon nanotube layer.  
     
     
         9 . The apparatus as recited in  claim 5 , wherein the low work function material is an alkali material.  
     
     
         10 - 14  (cancelled)  
     
     
         15 . A method for making a field emission cathode comprising the steps of 
 providing a substrate;    depositing a carbon nanotube layer on the substrate; and    inserting an alkali material into the carbon nanotube layer.    
     
     
         16 . The method as recited in  claim 15 , wherein the inserting step further comprises the step of depositing a layer of the alkali material on the carbon nanotube layer.  
     
     
         17 . The method as recited in  claim 15 , wherein the inserting step further comprises the step of doping the carbon nanotube layer with the alkali material.  
     
     
         18 . The method as recited in  claim 15 , wherein the inserting step further comprises the step of: 
 intercalating the alkali material into the carbon nanotube layer.    
     
     
         19 . A method for making a field emission cathode comprising the steps of providing a substrate; 
 depositing a carbon nanotube layer on the substrate;    inserting an alkali material into the carbon nanotube layer; and    enclosing the cathode in a low pressure gaseous environment.    
     
     
         20 . The method as recited in  claim 19 , wherein the inserting step further comprises the step of depositing a layer of the alkali material on the carbon nanotube layer.  
     
     
         21 . The method as recited in  claim 19 , wherein the inserting step further comprises the step of doping the carbon nanotube layer with the alkali material.  
     
     
         22 . The method as recited in  claim 19 , wherein the inserting step further comprises the step of intercalating the alkali material into the carbon nanotube layer.