Functionalized and coated carbon nanotubes via atomic layer deposition
Carbon nanotubes have remarkable electrical and optical properties that have not been extensively commercialized in part due to difficulties making robust and high quality devices containing them. One current difficulty is the lack of an effective technique to uniformly coat nanotubes with dielectrics while retaining the remarkable electrical and optical properties. Atomic layer deposition (ALD), has previously not been available for coating carbon nanotubes because their surface is not receptive to ALD precursors. The invention involves using chemical precursors to absorb to the surface of the nanotubes (including single walled carbon nanotubes), forming receptor sites for the deposition of coaxial thin films (dielectrics, metals, etc.) by ALD that are exceptionally thin, continuous, and radially isotropic.
A wide range of nanoscale devices and structures can be produced using this invention's non-covalent functionalization technique. For example, a functionalized carbon nanotube may be coaxially coated with a high-K dielectric layer and a selected conducting layer, to form a surround-gate transistor with large charging energies. Alternatively, the functionalization layer could enable highly customizable coatings (e.g., hydrophilic surfaces for medical application) as well as rapid, templated manufacture of hollow nanotube structures. Carbon nanotube based transistors have been fabricated using techniques compatible with chip fabrication, showing how the approach is amenable to mass manufacturing.