Alex Stram, The University of Texas at Austin

"Probing excitonic states in 2D transition metal dichalcogenides using Microwave Impedance Microscopy”

Abstract: Excitons are of particular interest in the monolayer group VI transition metal dichalcogenides (TMDs) due to their exceedingly large binding energies on the order of hundreds of meV. Strong excitonic resonances, at optical frequencies, can be observed even at room temperature, but typical optical probes are limited to high frequency detection. Microwave Impedance Microscopy (MIM) is a low frequency reflectometry technique that can access excitonic behaviors in the DC limit. This talk will feature photoconductive MIM measurements of monolayer TMDs using visible wavelength laser excitation. I will then move on to explain new results suggesting long-lived insulating excitonic states in monolayer tungsten disulfide.