Thursday, June 15, 2006

US Patent 7060356 - Nanotube Array Fabrication Using Differing Catalytic Materials

There are a variety of techniques used for fabricating uniform arrays of vertical nanotubes, such as the use of orienting electrostatic fields during CVD or the use of anodic aluminum oxide templates. While these methods are useful in manufacturing nanotubes for some devices, such as flat panel displays, other applications require overlapping nanotubes so as to create interconnections between the nanotubes. For example, nanotube-based memory, switching, or logic systems require connections between nanotubes to be formed parallel to the substrate on which the nanotubes are grown. The inventors of this patent have developed a methodology of growing vertical nanotubes to bend in particular directions by using different catalytic growth materials with differing associated growth rates. This allows for the formation of interconnections being particular bent nanotubes. Claim 6 reads:

6. A carbon nanotube-based device comprising: a substrate; a plurality of nano-sized catalytic particles formed on the substrate; and an aligned carbon nanotube array extending from the nano-sized catalytic particles; wherein said nano-sized catalytic particles each comprise a catalyst material and at least two different catalyst-doped materials which are respectively capable of causing different rates of synthesis of the carbon nanotubes so as to adjustably define a desired direction of growth of said array.

This patent joins some other recent fundamental carbon nanotube patents emerging from China useful for upcoming device applications.