Hybrid nanodevices

Vladimir Mitin

Dr. Mitin is interested in hybrid nanomaterials for multifunctional structures and devices. He is funded by National Science Foundation and NASA. The concept of forming hybrid materials is shown below:

Using functionalized nanoparticles (FNP) as building blocks, which may have the atom-like electronic states, controllable coupling, high sensitivity to bio-chemical agents, high selectivity to electromagnetic quanta, small absolute fluctuations – small noise record scalability, compatibility with organic environment, multifunctional structures and devices can be formed as indicated in the following figure.

The mission is to combine efforts in nanoparticle technology with nanoengineering and biophysics to realize new applications with superior performance.

              The main goals of his research are:

•  To advance and establish the basic science and technology needed to assemble and utilize FNP;

•  To develop methods to assemble FNP into multifunctional structures;

•  To develop multiparametric multi-analte sensors for precise measurements of various physical parameters and key chemical and biological agents;

•  To explore and utilize new concepts of integrated nanodevices based on nanoparticle sensors.

Materials, Devices, and Circuit Simulations

Modeling nanodevices with single-quantum sensitivity is the mainstream in the research of the Materials, Device and Circuit Simulations Laboratory recently established at the Electrical Engineering Department by Vladimir Mitin, professor, department chair and lab director. The theoretical studies involve investigations of fundamental processes in nanostructures, multiscale simulations, and, finally, design and optimization of novel nanodevices. Experimental tools for nanoscale manipulations are still expensive and resources are limited, so the theoretical research in nanoengineering plays a critical role yielding intellectual results and forming our choices and preferences as a society.

Together with Andrei Sergeev, EE research associate professor, Mitin looks at fundamental problems in transport phenomena, investigating how quantum interference of various scattering mechanisms modifies kinetics processes. For example, in metallic nanostructures the interference between electron-phonon and electron scattering from boundaries and defects changes drastically the electron cooling rate. It can be increased or decreased by a few orders of magnitude depending on character of impurities and boundaries. These theoretical results were supported by experiments of Michael Gershenson (Rutgers) who observed record-long 25-millisecond electron relaxation in nanopatterned Hf films at milliKelvin temperatures, and by Juhn-Jong Lin (Taiwan), who demonstrated fast relaxation in metallic alloys with strong substitution disorder. Very recently, measurements by Jonathan Bird, EE professor, demonstrated that the interference phenomena in electrical resistivity of nanocomposite materials can dominate over traditional mechanisms even at room temperatures.

With Nizami Vagidov, EE research assistant professor, Mitin investigates solid-state nanoemitting devices that are vital for applications in such areas as medical diagnostics and single-molecule spectroscopy. The nanoemitters radiate in the wide range of electromagnetic spectrum from terahertz to infrared. In their research they moved from modeling structures of the order of hundred nanometers (left part of the Figure) to the ten nanometer structures (right part of the Figure). They take into account the atomistic nature of the structure using advanced, first principles simulation techniques such as sp 3 sd 5 tight-binding model that allow to take into account each single atom or each layer of atoms as shown in the left part of the Figure.

Fundamental research is a starting point for device simulations, which are based on high level methods of modern quantum dynamics and kinetic theory, including the quantum transport equation, Keldysh diagram technique for nonequilibrium processes, and the recursive Green's function method. The results of modeling are widely used by experimental groups to construct novel nanosensors with ultimate quantum sensitivity. For example, one of the long-term projects represents joint efforts with Boris Karasik (JPL, Pasadena) to build ultrasensitive detector of submillimeter photons for future NASA astronomy missions, such as Single-Aperture FIR Observatory (SAFIR), Submillimeter Probe of the Evolution of Cosmic Structure (SPECS), and Space Infrared Telescope for Cosmology and Astrophysics (SPICA). Another recently started with UB colleagues Alexander Cartwright, Frank Bright, Mark Swihart, and Andrea Markelz projects are devoted to modeling nanoparticle sensors aimed for medical diagnostics.

 

 

 

              The long-term engineering objective of the laboratory is not only to get new results but to deliver via courses to graduate and undergraduate students that computational simulations at nanoscale should be pursued as a strong intellectual discipline, otherwise poorly-understood small atomic-scale effects can ruin the design of the whole system.