Seminar Date: Tuesday, February 3, 2026
Time: 11:00 AM PT
Location: 67-3111 & Zoom
Talk Title: Nanoscale Light Emission in Gated Transition Metal Dichalcogenides
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Abstract:
The electronic and optical properties of van der Waals (vdW) materials are governed not only by their intrinsic atomic structure but also by subtle nanoscale inhomogeneities such as point defects, wrinkles, and domain boundaries. Understanding how these structural variations modulate excitonic and charge dynamics is essential for advancing next-generation quantum and optoelectronic devices based on two-dimensional semiconductors. However, directly probing this intimate relationship requires techniques capable of addressing light–matter interactions with both nanometer spatial resolution and spectroscopic sensitivity.
In this work, we employ a low-temperature scanning tunnelling microscope (STM) to investigate the excitonic luminescence of a gated monolayer transition metal dichalcogenide (TMD) supported on hexagonal boron nitride. This approach unites the atomic-scale spatial precision of STM with the optical sensitivity of luminescence spectroscopy, enabling direct visualization of local excitonic emission with sub-nanometer resolution. Our measurements reveal sharp emission lines corresponding to charged excitons, whose intensities and emission energies exhibit pronounced spatial variations gate dependence correlated with the nanoscale topography and electrostatic landscape of the vdW heterostructure.
By mapping the excitonic emission across the sample, we uncover how point defects and local structural distortions influence exciton localization and recombination processes. Resolving such variations at the atomic scale provides new insights into the interplay between electronic structure, excitonic dynamics, and disorder in TMD monolayers.
I will present our new experimental framework for nanoscale optical spectroscopy in two-dimensional semiconductors, discuss its implications for understanding exciton physics, and outline how this platform can be extended toward the coherent control of excitonic and correlated phenomena with sub-nanometer precision. Our results establish a foundation for probing and engineering optoelectronic effects in complex vdW heterostructures, paving the way toward atomic-scale control of light–matter interactions in quantum materials.
Bio:
Batyr Ilyas earned his B.S. degree in Physics from Nazarbayev University in Astana, Kazakhstan, and his Ph.D. in Physics from the Massachusetts Institute of Technology (MIT) in Cambridge, MA. At MIT, his research focused on using tailored intense terahertz pulses to manipulate the magnetic properties of layered antiferromagnets via nonlinear phononics, as well as probing their ultrafast dynamics. In 2024, he joined the University of California, Berkeley, and Lawrence Berkeley National Laboratory as a Postdoctoral Researcher. His current work investigates local optical, electronic, and lattice dynamics in correlated electron systems using scanning probe microscopy techniques coupled with external laser sources.
