What is our logo?
Our MRSEC logo shows the arrangement of atoms at the surface of a crystal. Crystals are made up of layers, or "planes" of atoms, perfectly stacked in an ordered pattern. Because this surface has been cut at a slight angle to the crystal planes, it appears "stepped" (we call this type of surface a vicinal surface). Modern scanned-probe microscopes, such as the STM, allow us to see the atoms at the surface of a crystal, producing images very similar to this one.

University of Maryland

Materials Research Science and Engineering Center

IRG 1: Low-Dimensional Interfaces

An electrical current in a nanoscale structure is perturbed by scattering at atomic scale features on its surfaces. Schematic illustrates the use of a scanned probe tip to monitor the resulting effects at the surface. Inset shows an STM image of real nanoscale features (islands and pits ~0.25 nm high) on a silver surface.

The physical experiment corresponding to the schematic is shown in this Scanning Electron Microscope image. The large block to the right holds a cantilever bar with a sharp probe tip, shown in expanded view in the insert. The tip is positioned above one silver strip through which current is flowing. Real-time measurements show the atomic scale features moving in response to the electrical current.

Senior Investigators

• William G. Cullen, Physics
• Theodore L. Einstein (leader), Physics
• Michael S. Fuhrer, Physics
• Raymond J. Phaneuf, Materials Science & Engineering
• Janice E. Reutt-Robey (leader), Chemistry & Biochemistry
• John D. Weeks, IPST

Seed-Funded Collaborator

• Dionisios Margetis, Mathematics

Research Goals

Controlling electronic transport and recombination at boundaries between different materials is the key to progress in a myriad of applications including device physics, nano-bio mimetics, energy harvesting and photonics. Revolutionary opportunities have opened in all of these areas through the use of nanoscale materials structures, with parallel new challenges resulting from the concomitant change in the ratio of surface and bulk properties. We directly access low-dimensional interfaces of nanostructures by fabricating layered materials and ultra-thin films with domain and interface boundaries accessible to scanned probe and electron microscopies. We combine the structural characterization of interfaces with in situ measurement of device properties by fabricating the materials of interest into model thin-film transistor stuctures.

The objective of this IRG is to optimize nanoscale interface structures for electron transport, and charge separation and recombination. To do so, we apply a full range of tools from theoretical modeling of interface structure based on fundamental interactions, to device preparation and characterization. Materials systems understudy include graphene, C60 and molecular organic semiconductors.

Highlights

• Electric Potential Metrology on the Nanoscale
• Bilayer Graphene Photon Detector
• Metal Atom-Directed Traffic: Building Efficient 3-D Materials
• For the complete list, see the Highlights page

Publications

• View the IRG 1 publications list

IRG 1 Group Leaders

Janice Reutt-Robey

Professor, Chemistry & Biochemistry

Ted Einstein

Professor, Physics