The Keck Atomic Imaging and Manipulation System (AIMS) is adding atomic-scale manipulation capabilities to a transmission electron microscope (TEM) that is capable of near-atomic-resolution imaging of carbon nanotubes and other small structures. This system will be used to study the details of atomic lattice deformations for nanotube structures under stress and other atomic-resolution structures.

The AIMS project presents difficult challenges in the integration of atomic scale motion control, force sensing and in-situ electrical characterization within the extremely tight confines of the sample stage of a TEM. This integration within the tight confines of the TEM sample volume will initially be implemented using MicroElectroMechanical Systems (MEMS). MEMS technology applies processing techniques common to silicon electronic device fabrication to create actuating and sensing systems integrated onto silicon chips.

The user interface paradigms employed to build the NIMS system will be re-used in the AIMS sys-tem. Although there are no AFM scans in AIMS, the models and projective texture alignment techniques will be similar. The first step has been preparing prototype applications using different visualization dis-play libraries to select the most effective existing toolkit for this application.

There are two broad classes of experiments driving AIMS development: mechanical contact and electrical transport in nanoscale junctions.

Nanoscale Mechanical Contact: NSRG researchers seek to explore the configuration of the atoms in the contact region between carbon nanotubes. This study will include the distortion of atomic arrangements and the re-bonding of atoms across the interface, energy loss, and electron transport. It is predicted that distortion of the contacting surfaces (right figure) occurs because of the strong attractive forces that bind materials together, but no one has imaged these interfaces in contact for moving nano-scale devices. It has been predicted that the local distortion can dramatically change the properties of the interface, increasing energy loss during motion and enhancing electron transport.

While a TEM by itself can image contact regions, manipulation capabilities are essential for creating particular arrangements of interest (tee junctions, sliding rails, etc.), and for creating motion. AIMS will be used to explore: atomic-scale distortion during motion, interfacial wear at the atomic scale during the sliding of lattices, and the atomic origins of friction and energy flow.

Nanoscale Electrical Junctions: The AIMS will also be used to move nanomaterials into atomic contact. Experiments target both nanotube-nanotube junctions and nanotube-nanoparticle junctions. For the former, new carbon structures with positive and negative curvature have been proposed to form inte-grated tee junctions. In this case, the nanotubes are not simply lying on top of one another, but are inti-mately connected like the tee junction of a water pipe. The figure at the right is an SEM image of a crossed-nanotube device created in the NSRG laboratory (the nanotubes, about 2 nm in diameter, are the very thin crossing connections).

The AIMS is being made possible by a generous gift from the W. M. Keck Foundation and by support from the University of North Carolina at Chapel Hill.

For more information

See Taylor's talks in Taiwan in the Fall of 2002 and various publications in the dissemination web page.