The core of my group’s research:
The reduced dimensionality of nanostructures and the strong manifestation of quantum effects in them lead to interesting phenomena and a plethora of possibilities for studying fundamental physics and applying the knowledge gained to create new devices and enable new technologies. At its core, our group’s research is concerned with fabricating and exploring nanostructures, with emphasis on the interaction of electrons, photons and phonons with and in them. More specifically, we investigate the movement of electrons over and through energy barriers (both within solids and into a vacuum), using excitation by heat, light, field, or other electrons, with phonons sometimes playing mediatory roles. We thus study both solid-state and vacuum devices, as well as the interface between the solid and vacuum, where many interesting things happen. The primary nanomaterial of interest is the carbon nanotube, although we also work with nanostructures of other materials as warranted.
The applications we pursue:
These generally fall under one of three categories:
Energy conversion: a significant portion of our work is on creating new thermoelectric and thermionic devices for the efficient conversion of heat-to-electricity and light-to-heat-to-electricity. For example, based on an unusual light-induced heating mechanism in arrays of carbon nanotubes (the “Heat Trap” effect) discovered by our group, we demonstrated a compact thermionic solar cell – something that had not been possible in the past using bulk materials.
Nanoelectronics: this includes solid-state and vacuum nanoelectronics devices, with emphasis on the creation of new or improved electron sources as the foundational block of vacuum electronics. Another topic of interest includes high-gain electron multiplication devices.
Free-electron devices: the focus here again is on electron emission and transport, with the goal of creating electron sources that could be applied in electron-beam microscopy, lithography, free-electron lasers and terahertz sources, machining and welding technologies. Another aspect of this work includes the study of the imaging mechanisms of nanostructures in electron microscopy.
Our everyday activities:
The everyday activities involved in research projects in our group are diverse and typically include device design, micro/nanofabrication in the cleanroom, nanostructure growth and deposition, electron and scanning-probe microscopy, building experimental apparatus such as high- or ultra-high-vacuum systems, electronic characterization and sensitive instrumentation, and working with lasers and optics. We complement our experimental efforts with modeling and simulation using methods ranging from continuum modeling (such as finite-element analysis) to classical molecular dynamics to first-principles, quantum-mechanical techniques like the Hartree-Fock theory, configuration-interaction, perturbation theory and the density-functional theory.