Controlled deposition of nanotubes

Abstract

By a simple method single suspended carbon nanotubes (CNTs) are deposited at predetermined locations on a pre-patterned device. A narrow trench is first formed on the device at the desired location for depositing a CNT. A fluid drying deposition process is then used to mount the CNT at the chosen location. A droplet of a solvent containing the CNTs in suspension is deposited at the desired location, and the solvent is allowed to evaporate. This leaves the CNT bridging the trench at the selected location. The effect is enhanced by applying an electric field. The method is also applicable to other nano-elongated objects such as nanowires and biomolecules.

1 . A method for controllably depositing a nanotube between a pair of contact points, comprising: 
 forming a trench between the pair of contact points;    forming a suspension of nanotubes in an evaporatable solvent;    applying a droplet of the solvent with suspended nanotubes between the pair of contact points;    allowing the solvent to evaporate, leaving a nanotube connecting the pair of contact points.    
     
     
         2 . The method of  claim 1  wherein the trench has a micron-sized width.  
     
     
         3 . The method of  claim 2  further comprising applying an aligning electric field between the pair of contact points.  
     
     
         4 . The method of  claim 3  wherein the aligning electric field is applied by applying a voltage of about 5-10V between the pair of contact points.  
     
     
         5 . The method of  claim 1  further comprising applying an aligning electric field between the pair of contact points.  
     
     
         6 . The method of  claim 1  wherein the nanotubes are carbon nanotubes.  
     
     
         7 . The method of  claim 1  wherein the solvent is acetone.  
     
     
         8 . The method of  claim 1  wherein the trench has a width such that a substantial capillary force acts on the droplet.  
     
     
         9 . The method of  claim 1  further comprising removing metallic nanotubes and leaving semiconducting nanotubes.  
     
     
         10 . The method of  claim 9  wherein the metallic nanotubes are removed by passing an electric current therethrough to burn off the metallic nanotubes.  
     
     
         11 . A device comprising: 
 a device substrate having one or more pairs of contact points thereon; and    a nanotube connected between each contact pair by the method of  claim 1 .    
     
     
         12 . A device comprising: 
 a device substrate having one or more pairs of contact points thereon; and    a nanotube connected between each contact pair by the method of  claim 3 .    
     
     
         13 . A device comprising: 
 a device substrate having one or more pairs of contact points thereon; and    a nanotube connected between each contact pair by the method of  claim 9 .    
     
     
         14 . A method for controllably depositing a nano-elongated object between a pair of contact points, comprising: 
 forming a trench between the pair of contact points;    forming a suspension of nano-elongated objects in an evaporatable solvent;    applying a droplet of the solvent with suspended nano-elongated objects between the pair of contact points;    allowing the solvent to evaporate, leaving a nano-elongated object connecting the pair of contact points.    
     
     
         15 . The method of  claim 14  wherein the trench has a micron-sized width.  
     
     
         16 . The method of  claim 15  further comprising applying an aligning electric field between the pair of contact points.  
     
     
         17 . The method of  claim 14  further comprising applying an aligning electric field between the pair of contact points.  
     
     
         18 . The method of  claim 14  wherein the nano-elongated objects are selected from nanotubes, nanowires, and biomolecules.