Talks & Lectures
20 Feb 2019
Carnegie 315

From Band Gaps to Bound Excitons: Disentangling Optical Transitions in TMDCs Even at Nanoscale Dimensions

Nanotechnology Seminar Series: Jim Schuck, Columbia University

Jim Schuck

ABSTRACT

By using plasmonics for nano-optical spectroscopic imaging, we cross the boundary from insufficient to sufficient resolution, mapping critical optoelectronic properties in the exciting transition metal dichalcogenide (TMDC) materials at their native length scales. In doing so, we uncover new optoelectronic regions and spatially-varying features in single-layer TMDCs (1L-TMDCs) that were hidden in prior studies. These findings have broad implications for the development of atomically thin transistors, quantum optical components, photodetectors and light-emitting devices.

Most recently, we are demonstrating that a model hybrid architecture, a nano-optical antenna and a 1L-WSe2 nanobubble, activates the optical activity of bound exciton states at room temperature and under ambient conditions, thereby laying out a possible path for realizing room-temperature single-photon sources in high-quality 2D semiconductors.

In the final part of the talk, I will describe our development of a novel type of luminescent nanocrystal, upconverting nanoparticles (UCNPs). Lanthanide-doped upconverting nanoparticles (UCNPs) overcome problems of photostability and continuous emission inherent in fluorescent molecules and quantum dots, but their brightness has been limited by a poor understanding of energy transfer within the nanocrystal and an unavoidable trade-off between brightness and size. I will discuss our novel design paradigms that have resulted in UCNPs that are many orders of magnitude brighter than existing compositions, allowing us to visualize single UCNPs as small as fluorescent proteins, and to create ultralow-threshold room-temperature nanolasers for the first time.

I will finish by with our initial attempts at applying these nano-probes to deep-tissue biological sensing and brain imaging.

BIOGRAPHY

Jim Schuck is an associate professor of mechanical engineering at Columbia University. He earned his B.A. in physics at U.C. Berkeley and his Ph.D. in applied physics at Yale University. He then did his postdoctoral studies with professor W. E. Moerner at Stanford University, studying optical nanoantennas and single-molecule spectroscopy. Schuck's group aims to characterize, understand and control nanoscale light-matter interactions, with a primary focus on sensing, engineering and exploiting novel optoelectronic phenomena emerging from nanostructures and interfaces.

Hosted by mechanical engineering assistant professor Fan Yang.

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