Field emission tips, arrays, and devices

Abstract

A field emission tip includes a base with a central portion and a tapered portion. The central portion of the base includes a peripheral surface, at least a portion of which is oriented substantially vertically or perpendicularly relative to a plane in which a substrate from which the field emission tip protrudes resides. An apex may be located at an exposed end of the central portion of the base. The tapered portion of the base includes an inclined surface that extends toward the exposed end of the central portion of the base. The tapered portion of the base may be formed from material that is redeposited as the emission tip is fabricated. The apex may be formed, at least in part, from a low work function material, such as one or more of aluminum titanium silicide, titanium silicide nitride, titanium nitride, tri-chromium mono-silicon, and tantalum nitride. Field emission arrays and field emission displays that include such field emission tips are also disclosed.

1 . A field emission tip, comprising a structure including at least one of semiconductive material and conductive material, the structure comprising: 
 a base with: 
 a central portion including a peripheral surface with a substantially vertical sidewall; and  
 a tapered portion surrounding the central portion and including an inclined surface extending toward an exposed end of the central portion; and  
   an apex at the exposed end of the central portion of the base.    
   
   
       2 . The field emission tip of  claim 1 , wherein a height of the at least substantially vertical sidewall exceeds a width of the central portion.  
   
   
       3 . The field emission tip of  claim 1 , wherein the apex comprises a low work function material.  
   
   
       4 . The field emission tip of  claim 3 , wherein the low work function material comprises at least one of aluminum titanium silicide, titanium silicide nitride, titanium nitride, tri-chromium mono-silicon, and tantalum nitride.  
   
   
       5 . The field emission tip of  claim 1 , wherein the apex has a lateral width of less than about 100 nm.  
   
   
       6 . The field emission tip of  claim 1 , wherein the apex has a lateral width of less than about 50 nm.  
   
   
       7 . A field emission tip, comprising a structure including at least one of semiconductive material and conductive material, the structure comprising: 
 a base with: 
 a central portion including a peripheral surface with a substantially vertical region; and  
 a tapered portion including an inclined surface that extends toward an exposed end of the central portion, the tapered portion surrounding the substantially vertical region; and  
   an apex at the exposed end of the central portion of the base, the apex having a lateral width of less than about 100 nm.    
   
   
       8 . The field emission tip of  claim 7 , wherein the apex has a lateral width of less than about 50 nm.  
   
   
       9 . The field emission tip of  claim 7 , wherein the apex comprises a low work function material.  
   
   
       10 . The field emission tip of  claim 9 , wherein the low work function material comprises at least one of aluminum titanium silicide, titanium silicide nitride, titanium nitride, tri-chromium mono-silicon, and tantalum nitride.  
   
   
       11 . A field emission array, comprising: 
 a substrate; and    at least one substantially pointed tip protruding from the substrate, the at least one substantially pointed tip comprising at least one of a semiconductive material and a conductive material, the at least one substantially pointed tip including a peripheral surface, at least a first portion of the peripheral surface being oriented substantially perpendicularly relative to the substrate and at least a second portion of the peripheral surface at an end of the at least one substantially pointed tip being oriented at an angle relative to the substrate to form an apex; and    at least one surrounding element including a surface that tapers toward an exposed end of the at least one substantially pointed tip and that surrounds at least the first portion of the at least one substantially pointed tip.    
   
   
       12 . The field emission array of  claim 11 , wherein the first portion of the peripheral surface is adjacent the substrate.  
   
   
       13 . The field emission array of  claim 11 , wherein a height of the first portion of the peripheral surface relative to the substrate exceeds a width of the at least one substantially pointed tip.  
   
   
       14 . The field emission array of  claim 11 , wherein an end of the at least one substantially pointed tip comprises a low work function material.  
   
   
       15 . The field emission array of  claim 14 , wherein the low work function material comprises at least one of aluminum titanium silicide, titanium silicide nitride, titanium nitride, tri-chromium mono-silicon, and tantalum nitride.  
   
   
       16 . The field emission array of  claim 11 , wherein the at least one surrounding element comprises redeposition material adjacent to at least the first portion of the peripheral surface.  
   
   
       17 . The field emission array of  claim 11 , wherein an apex of the at least one substantially pointed tip has a lateral width of less than about  100  nm.  
   
   
       18 . The field emission array of  claim 11 , wherein an apex of the at least one substantially pointed tip has a lateral width of less than about  50  nm.  
   
   
       19 . A field emission display, comprising: 
 an anode display screen;    a cathode spaced apart from the anode display screen, the cathode including: 
 a substrate;  
 at least one substantially pointed tip protruding from the substrate, the at least one substantially pointed tip comprising at least one of a semiconductive material and a conductive material, the at least one substantially pointed tip including a peripheral surface, at least a base portion of the peripheral surface being oriented substantially perpendicularly relative to the substrate and at least a tip portion of the peripheral surface being oriented at an angle relative to the substrate;  
 at least one surrounding element that tapers toward an exposed end of the at least one substantially pointed tip and that surrounds at least the base portion of the peripheral surface of the at least one substantially pointed tip; and  
 a gate through which the at least one substantially pointed tip is exposed;  
   a substantial vacuum between the anode display screen and the cathode; and    a voltage source associated with the anode display screen, the gate, and the cathode to provide a potential difference between the cathode and the gate and between the cathode and the anode display screen.    
   
   
       20 . The field emission display of  claim 19 , wherein at least the base portion of the peripheral surface is adjacent the substrate.  
   
   
       21 . The field emission display of  claim 19 , wherein a height of at least the base portion of the peripheral surface relative to the substrate exceeds a width of the at least one substantially pointed tip.  
   
   
       22 . The field emission display of  claim 19 , wherein a top portion of the at least one substantially pointed tip comprises a low work function material.  
   
   
       23 . The field emission display of  claim 22 , wherein the low work function material comprises at least one of aluminum titanium silicide, titanium silicide nitride, titanium nitride, tri-chromium mono-silicon, and tantalum nitride.  
   
   
       24 . The field emission display of  claim 19 , wherein the at least one surrounding element comprises redeposition material adjacent to at least the first portion of the peripheral surface.  
   
   
       25 . The field emission display of  claim 19 , wherein an apex of the at least one substantially pointed tip has a diameter of less than about 100 mn.  
   
   
       26 . The field emission display of  claim 19 , wherein an apex of the at least one substantially pointed tip has a diameter of less than about 50 mn.