Seminar Series: Dr. Igor V. Bondarev, Friday, 01/26/2018, 11:00 A.M
JSNN Seminar Series
Title: “Understanding the Collective Excitations in Quisi-2D Nanostructures of Metals and Semiconductors.”
Speaker: Dr. Igor V. Bondarev
Department of Math and Physics, North Carolina Central University, Durham, NC
Date and Time: Friday, 01/26/2018, 11:00 A.M.
Location: JSNN Auditorium
In this talk, I will briefly review the latest experiments [1-6] and enlarge on our recent theoretical efforts to develop a physical understanding of the properties of quasi-2D semiconductor and metallic nanostructures, efforts that have uncovered their intriguing optical attributes lending themselves to new attractive device applications. For instance, we show that the binding energies of the charged and neutral exciton complexes (trion and biexciton) formed by indirect excitons in layered quasi-2D semiconductors can be significant — up to a few tens of meV — for interlayer distances ~3–5 Å typical of transition metal dichalcogenide heterostructures . Exciton complexes in semiconductor coupled quantum wells and bilayer van der Waals bound transition metal dichalcogenide systems are of interest for nonlinear optics and spinoptronics applications [5‐8]. We also develop a theory of the intra-intermolecular exciton intermixing and polarization dynamics for quasi-2D crystalline semiconductors of organic molecules with two isolated low-lying Frenkel exciton states such as transition metal phthalocyanines [2,3]. The third-order nonlinear polarization response function we derive  exhibits dynamical reorientation of the exciton transition dipole polarization (initially excited in the molecular plane) towards the axis of the molecular chain. Such a dynamical reorientation pinpoints the preferential direction of the charge separation process for electron-hole pairs excited in these materials. Our results can be used for the proper interpretation of the optical properties of crystalline transition metal phthalocyanines — next generation organic semiconductors for advanced optoelectronics. Last but not least, we study theoretically confinement related effects in the optical response of ultrathin plasmonic films of finite thickness . We show that, while being constant for relatively thick films, the plasma frequency acquires spatial dispersion typical of 2D materials, gradually shifting to the red with the film thickness reduction. This explains recent experiments done on TiN films of controlled variable thickness , offering ways to tune the spatial dispersion (and so the magnetic permeability ) and the magneto-optical properties of ultrathin plasmonic films and metasurfaces — not only by varying their material composition but also by controlling their thickness and by choosing substrate and superstrate materials appropriately.
This research is supported by the UNC-GA Research Opportunity Initiative grant (NCSU-NCCUUNCChapel Hill collaboration), the US Department of Energy (DE-SC0007117), and the US National Science Foundation (ECCS-1306871, DMR-1506775).
Dr. Igor V. Bondarev is tenured Professor of Physics in the Department of Mathematics and Physics at North Carolina Central University, Durham, North Carolina. Dr. Bondarev earned his MS (1989, Physics, with Honors) and PhD (1994, Theoretical Physics) degrees from the Belarusian State University in Minsk, Belarus. He earned his DSc degree (2001, Theoretical Solid State Physics) from the National Academy of Sciences of the Republic of Belarus in Minsk. (Doctor of Sciences in Physics and Mathematics is the Habilitation Degree awarded to less than one per cent of active former Soviet Union scientists having PhD.) In 1989-2005, Dr. Bondarev worked in the Theoretical Physics Lab of the Institute for Nuclear Problems at the Belarusian State University (last occupied position – Principal Research Associate/Group Leader). At the same time, as a visiting Professor he performed his research in Germany, France, Belgium, Italy, Poland, and Japan, supported by DAAD (Germany), OSTC (Belgium), JSPS (Japan), and other highly competitive visiting professorship fellowships. Dr. Bondarev has authored and co-authored over 180 research articles, including one US patent and five book chapters in collective monographs published by Nova Science, Taylor & Francis, CRC Press and American Scientific, USA. He presented his research at over 30 invited seminars and over 140 international conferences and symposia in Europe, China, Japan, Mexico, USA, and Canada. Dr. Bondarev is the recipient of the Presidential Young Investigator Award (Belarus, 1999-2001), NCCU College of Science & Technology Outstanding Faculty Research Award (2007, 2012), NCCU Faculty Senate Award for Scholarly Achievements (2007), NCCU Office of Sponsored Research Award for Technology Innovations (2012), and Research Grant Awards from the US National Science Foundation, the US Department of Energy, and the US Army Research Office. His current research interests are focused on the optoelectronic and sensory properties of semiconductor and carbon nanostructures, exciton/plasmon/polariton effects, efficient solar energy conversion with nanomaterials and nanobiophotonics.