Location
Physics : 401
Date & Time
April 25, 2019, 11:00 am – 12:30 pm
Description
ADVISOR: Dr. Michael Hayden
TITLE: Carrier Dynamics in Transition Metal Dichalcogenides via Time-Resolved Terahertz Spectroscopy
ABSTRACT: Atomically thin transition metal dichalcogenides (TMDs) are a class of two-dimensional materials that have attracted much attention in the past decade because of their unique properties. One such property is the existence of tightly bound excitons at room temperature. These excitons are a consequence of quantum confinement and the reduced dielectric environment enhancing the Coulombic interactions between electrons and holes. The strong Coulombic interactions in TMDs are sufficient to support charged excitons (trions) as well. As people look to fabricate devices out of TMDs, a fundamental understanding of how excitons, trions, electrons, holes, and other quasiparticles behave in these two-dimensional systems is essential. Time-resolved terahertz spectroscopy (TRTS) is a powerful tool that probes charge carrier dynamics in materials on the sub-picosecond timescale. One of the main advantages that TRTS presents over other techniques is that terahertz radiation is particularly sensitive to the response of free charges, excitons, trions, as well as other charged quasiparticles. Therefore, in this work, I propose utilizing TRTS to study the charge carrier dynamics in TMDs. Since charged quasiparticles have distinct spectral signatures in the terahertz frequency range, analyzing the complex dielectric response extracted from TRTS data will allow the behavior of charge carriers in TMDs to be fully characterized.
TITLE: Carrier Dynamics in Transition Metal Dichalcogenides via Time-Resolved Terahertz Spectroscopy
ABSTRACT: Atomically thin transition metal dichalcogenides (TMDs) are a class of two-dimensional materials that have attracted much attention in the past decade because of their unique properties. One such property is the existence of tightly bound excitons at room temperature. These excitons are a consequence of quantum confinement and the reduced dielectric environment enhancing the Coulombic interactions between electrons and holes. The strong Coulombic interactions in TMDs are sufficient to support charged excitons (trions) as well. As people look to fabricate devices out of TMDs, a fundamental understanding of how excitons, trions, electrons, holes, and other quasiparticles behave in these two-dimensional systems is essential. Time-resolved terahertz spectroscopy (TRTS) is a powerful tool that probes charge carrier dynamics in materials on the sub-picosecond timescale. One of the main advantages that TRTS presents over other techniques is that terahertz radiation is particularly sensitive to the response of free charges, excitons, trions, as well as other charged quasiparticles. Therefore, in this work, I propose utilizing TRTS to study the charge carrier dynamics in TMDs. Since charged quasiparticles have distinct spectral signatures in the terahertz frequency range, analyzing the complex dielectric response extracted from TRTS data will allow the behavior of charge carriers in TMDs to be fully characterized.
