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Electrical Control of Interlayer Exciton Dynamics in Semiconducting Atomically Thin Heterostructures: Nano Seminar Series

November 13, 2020 @ 2:00 pm - 3:00 pm

Prof. Luis A. Jauregui, UC Irvine, Physics
Zoom link: https://berkeley.zoom.us/j/92258130783
Van der Waals heterostructures constructed of 2-dimensional (2-D) materials such as single layer transition metal dichalcogenides (TMDs) have sparked wide interest because of their large excitonic binding energy, allowing the exploration of novel quantum optical effects in a solid-state system and new opto-electronic devices.
In this talk, I will discuss our results in van der Waals heterostructures formed by stacking together two different TMDs (forming a staggered heterojunction) encapsulated with hexagonal boron nitride (h-BN) with electrical contacts in each layer and a dual gate configuration.
Interlayer excitons, with electrons and holes residing in spatially separated quantum wells, have long lifetimes (> 200 nanoseconds, 5 orders of magnitude longer than intralayer exciton lifetimes). Because of their repulsive Coulomb interaction, they “diffuse” across the entire sample (20 m long) driven by interaction, allowing their manipulation towards condensation. We used local electric fields to localize interlayer excitons, and increase their local exciton densities to few 1012 cm-2 allowing the observation of signatures of Mott transitions. Also, we observed and manipulated long-lived charged interlayer excitons, by electrostatically doping the sample. When the chemical potential reaches the second conduction band in a TMD (MoSe2) we demonstrated the electrical tunability from spin-singlet to spin-triplet charged interlayer excitons. Our long-lived charged interlayer excitons can be used as carriers for quantum information.
Our results pave the way for novel optoelectronic devices as well as a step towards a solid-state platform for generating and exploring Bose-Einstein condensates at high temperatures, near-infrared tunable lasers and light emitting diodes.
Luis Jauregui did his PhD at Purdue and postdoc at Harvard with Philip Kim. He joined the UCI faculty this past spring.


November 13, 2020
2:00 pm - 3:00 pm


Zoom Session