Lake and Balandin Awarded NSF Grant for Topological Insulator Research

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Posted on July 11, 2011 by bcoe

July 7, 2011 — Professor of Electrical Engineering Roger Lake (photo, left) and Alexander Balandin, Professor of Electrical Engineering and Chair of the Materials Science and Engineering Program (photo, right), have been awarded a multi-year grant from the National Science Foundation to investigate and characterize the behavior of topological insulators, a new class of quantum materials with bulk insulating energy gaps and gapless Dirac-cone edge or surface states.
The successful project has the potential to lead to new technologies that exploit the low-dissipation, low-noise states of topological insulators for computation, communications, and sensors.
The electrons on the surfaces of topological insulators have many similarities to electrons in graphene, another material of intense interest. However, the electrons on the surfaces of topological insulators have even more special and peculiar properties. Bismuth telluride (Bi₂Te₃) and bismuth selenide (Bi₂Se₃) are examples of topological insulators, whose surface states are protected against time-reversal-invariant perturbations such as non-magnetic impurities, defects, and reconstruction. The charge is uniquely coupled to the spin, and charge current creates spin polarization. Since the surface states are topologically protected, and the momentum states are coupled to spin states, scattering is reduced and noise is suppressed.
Topological insulators have shown exceptional properties for thermoelectric, charge, and spin transport. These materials and properties will be investigated by Lake and Balandin’s research teams from an engineering electronics point of view. Devices that exploit these properties will be built, modeled and characterized, and the performance metrics and fundamental limits of such devices will be determined. Transformative concepts include the use of low-dissipation, low noise topologically protected states of topological insulators for electronic/spintronic devices and low-noise, low-power interconnects.
Their investigation will be simultaneously carried out both experimentally and theoretically. The project will (i) add to the fundamental knowledge of the material properties and physical processes in highly-scaled topological insulator materials; (ii) build, model, and characterize devices that exploit topological insulating properties for computation, signal processing, and sensing; (iii) determine the performance metrics and the fundamental limitations of such devices, (iv) explore the use of topological insulators for low-dissipation, low-noise interconnects; and (v) develop the electrochemical atomic layer deposition technique to grow few-atomic-layer films of topological insulators.
All materials will be extensively characterized using a wide range of methods including atomic force, scanning electron, and transmission electron microscopy, low energy electron diffraction, X-ray spectroscopy, Auger spectroscopy, electron probe micro-analysis, micro-Raman spectroscopy, electrical, and thermal measurements. Experimental measurements will be compared to device models and ab initio, density functional theory calculations of the electronic structure and vibrational modes of the thin film and nanowire materials.
This three-year investigation will be simultaneously carried out at both theoretically in Lake’s Laboratory for Terahertz and Terascale Electronics (LATTE) and experimentally in Balandin’s Nano Device Laboratory (NDL).