Columbia Technology Ventures

Controlled Carbon Nanotube Alignment in Electrical Devices

As silicon reaches its fundamental scaling limits, there has been intense effort in developing carbon nanotubes (CNTs) for electron transport in next-generation devices. This requires custom-positioned semiconducting CNTs in device architectures. This technology is a process for precisely positioning carbon nanotubes (CNTs) in electronic devices. Using AC dielectrophoresis and patterned metal posts or strips as guides, single-walled semiconducting CNTs can be precisely aligned and positioned in electrode gaps. The metal structures perturb the electric field, causing local field intensity enhancements to guide the nanotubes along a predictable path. Because this process precisely positions the CNTs in a variety of possible alignments, it can be used to make next-generation field effect transistors (FETs) along with lab-on-chip microelectrodes, silicon nanowires, and other nanotechnology devices.

Rapid, precise, and customizable carbon nanotube positioning using dielectrophoresis

CNT devices were initially fabricated by dispersing CNTs in a solvent and dropping them onto pre-patterned electrodes. This leads, however, to random nanotube deposition and offers no control over nanotube chirality, which determines whether CNTs are semiconducting or metallic. This technology, in contrast, uses 3D electric field simulations to optimize placement of sub-micron-sized metal structures, which offer predictive control of nanotube positions. Dielectrophoretic deposition controls the quantity and placement of CNTs on substrates, as well as the CNTs' geometric shape and overall architecture. This straightforward, single-step lithography supports rapid development of novel carbon nanotube materials, as well as streamlined production of carbon nanotube devices.

This technology has been tested using both experimental prototypes and computer simulations.

Lead Inventor:

Irving Herman, Ph.D.

Applications:

  • Production of similar materials containing Boron Nitride (BN) nanotubes, silicon nanowires, II-VI semiconductor nanowires, and other tube/wire-like structures
  • Nanotechnology applications: field effect transistors (FETs), sensors, lab-on-chip microelectrodes, coatings, optics, and other nanoelectrochemical systems

Advantages:

  • Control over the number of nanotubes assembled between the electrodes
  • Precise positioning of carbon nanotubes
  • Simulations provide high level of predictive control for carbon nanotube positioning
  • Ability to customize carbon nanotube geometry and architecture
  • Rapid and easy fabrication of devices with only one lithographic step

Patent information:

Patent Pending (US 20130228364)

Tech Ventures Reference: IR M06-035

Related Publications: