Method for batch fabricating electron emission source of electrophoresis deposited carbon nanotubes

Abstract

A method for batch fabricating electron emission source of electrophoresis deposited carbon nanotubes includes preparing a semi-manufactured cathode structure and a metallic plate connected with electrophoresis electrodes. The cathode structure and the metallic plate that are parallel to each other are separated with a fixed distance and are rinsed in an electrophoresis solution. A processe is performed to remove the bubbles formed in the cathode structure, and to electrophoresis deposit the carbon nanotubes onto the cathode structure. After each deposition process is completed, the cathode structure is baked under a low temperature so as to remove the residual solution remained on the cathode structure. After a homogeneous carbon nanotubes layer is deposited to form the electron emission source, a sintering process is performed so as to transfer the chargers into conductive metallic oxide salts. Thereby, the electron conduction of the carbon nanotubes and the cathode electrode layer is enhanced.

1 . A method for batch fabricating an electron emission source of electrophoresis deposited carbon nanotubes, the method comprising the steps of: 
 preparing a semi-manufactured cathode structure, performing an electrophoresis deposition to the semi-manufactured cathode structure by connecting the cathode structure and a metallic plate to an electrophoresis electrodes;    preparing an electrophoresis solution, pouring the prepared solution into a plurality of electrophoresis tanks, disposing parallelly separated cathode structure and metallic plate into the solution of first electrophoresis tank, turning on an anti-bubble device of the first electrophoresis tank to remove bubbles formed in the cathode structure, turning off the anti-bubble device, keeping the cathode structure in the solution for performing the electrophoresis deposition, removing the cathode structure from the solution, and baking the cathode structure with a low temperature so as to remove residual solution remained on the cathode structure;    rinsing the baked cathode structure into second electrophoresis tank for performing second electrophoresis deposition, turning on an anti-bubble device of the second electrophoresis tank to remove bubbles formed in the cathode structure, turning off the anti-bubble device, keeping the cathode structure in the solution for performing the electrophoresis deposition, removing the cathode structure from the solution, and baking the cathode structure with a low temperature so as to remove residual solution remained on the cathode structure, repeating this step as necessary until carbon nanotubes are homogeneously deposited on a cathode electrode layer and an electron emission source is formed; and    after the deposition process of the cathode structure is completed, baking the cathode structure with a low temperature so as to remove residual alcoholic solution on the cathode structure, next performing a sintering process for re-oxidating indium hydroxide on the cathode electrode layer back to indium oxide, thereby enhancing an electron conductivity of the carbon nanotubes and the cathode electron layer.    
   
   
       2 . The method as recited in  claim 1 , wherein the step for preparing the semi-manufactured cathode structure comprises: 
 forming the cathode electrode layer on a glass substrate, forming a dielectric layer on the cathode electrode layer, forming a gate layer on the dielectric layer, and forming a sagged area on the gate layer by means of lithography technology to expose the cathode electrode layer;    forming a protection layer on the surface of the gate layer, etching the dielectric layer to form the sagged area exposing the cathode electrode, and performing peeling operation to the protection layer; and    forming another protection layer to cover the dielectric layer and the gate layer, thereby completing the manufacturing process of the semi-manufactured cathode structure.    
   
   
       3 . The method as recited in  claim 1 , wherein the cathode electrode layer of the cathode structure is connected to the cathode of electrophoresis electrode, while an anode of the electrophoresis is connected to the metallic plate, the metallic plate being one of a platinum plate, a titanium plate and a screen plate.  
   
   
       4 . The method of  claim 1  wherein an electric field is provided by a power supply, which has an intensity of approximately 0.5˜10 V/cm.  
   
   
       5 . The method as recited in  claim 1 , wherein the carbon nanotubes made from arc discharge are multi-wall carbon nanotubes comprising an average length below 5 μm, and an average diameter below 100 nm.  
   
   
       6 . The method as recited in  claim 1 , wherein the solution contained in the electrophoresis tank comprises alcohol as solvent, pure water, carbon nanotube powder, and charger.  
   
   
       7 . The method as recited in  claim 6 , wherein the pure water added to the solution is about 1%˜10%.  
   
   
       8 . The method as recited in  claim 6 , wherein a weighted concentration of the carbon nanotube powder added to the solution is approximately 0.1%˜0.005%.  
   
   
       9 . The method as recited in  claim 6 , wherein the weighted concentration of the charger added to the solution is approximately 0.1%˜0.005%.  
   
   
       10 . The method as recited in  claim 6 , wherein the charger is selected from a conductive metallic salt oxide of indium chloride, indium nitride, and salt of tin after the electrophoresis process.  
   
   
       11 . The method as recited in  claim 1 , wherein the anti-bubble device is a blender rotor or an ultrasonic device.  
   
   
       12 . The method as recited in  claim 1 , wherein the anti-bubble device stirs the solution for 5 to 10 minutes so as to remove the bubbles in the cathode structure.  
   
   
       13 . The method as recited in  claim 1 , wherein the cathode structure is kept in the solution for performing electrophoresis deposition for 5 to 10 minutes after the anti-bubble device is turned off.  
   
   
       14 . The method as recited in  claim 1 , wherein a number of batch electrophoresis deposition processes can be increased or decreased according to the deposition quality of the fabricated electron emission source.  
   
   
       15 . The method as recited in  claim 1 , wherein the baking temperature is about 80° C.  
   
   
       16 . The method as recited in  claim 15 , wherein the baking process removes the residual solution remained on the cathode structure, the residual solution being alcohol.  
   
   
       17 . The method as recited in  claim 16 , wherein during the low temperature baking process that removes the residual alcoholic solution, indium chloride charger and electrolyte hydroxyl forms indium hydroxide.  
   
   
       18 . The method as recited in  claim 1 , wherein the sintering temperature is about 400° C.  
   
   
       19 . The method as recited in  claim 1 , wherein a conductive indium oxide is deposited on the cathode electrode layer to enhance the electron conductivity between the carbon nanotubes and the cathode electrode layer.  
   
   
       20 . The method as recited in  claim 1 , wherein the electrophoresis deposited carbon nanotubes of the electron emission source layer are easily adhered to the surface of the cathode electrode, whereby a homogeneous carbon nanotubes layer is easily formed, the average thickness of which is below 2 μm, and the sintered carbon nanotubes are deposited together with an indium oxide salt, which are not easily detached from the cathode structure.