Directed self-assembly of individual vertically aligned carbon nanotubes

The deposition of high-aspect-ratio particles such as carbon nanotubes may be done in sub-100-nm windows in insulating thin films over metal using electrophoresis. Surface charge on the insulator causes the windows to become nanoscopic electrostatic lenses. Under certain conditions only one nanotube will be deposited at the base of a window. Finite element analysis shows that the number of deposited nanotubes is controlled by the electric field and the geometry of the windows and nanotubes. This discovery enables the process integration of carbon-based electronics with more traditional technologies such as complementary metal oxide semiconductor using the current generation of lithography and process technology. Devices such as vertical field effect transistors and interconnected nanoprobe arrays may now be fabricated in the metal levels to facilitate three-dimensional polylithic circuit architectures.