Optical spectroscopy of two-dimensional crystals and van der Waals heterostructures

October 19, 2020
Prof. Tobias Korn (University of Rostock)
Following the discovery of graphene, many other layered materials have recently been studied in the limit of few or even single atomic layers. Among them, transition-metal dichalcogenides (TMDs) have garnered a lot of attention. While they are indirect-gap semiconductors in the bulk, monolayers are direct-gap semiconductors showing pronounced photoluminescence. Monolayer TMDs are characterized by a peculiar, multi-valley band structure and by tightly bound excitons, which are stable well beyond room temperature. I will present some results on low-temperature valley dynamics in these systems.
Going beyond monolayers, two-dimensional crystals can be stacked into van der Waals heterostructures. By combining two different TMDs, a type-II heterostructure is formed, in which electron-hole pairs are separated into adjacent layers. These remain Coulomb-correlated and form interlayer excitons. I will present some recent results on the nature of interlayer excitons, their dynamics, exciton-exciton interactions and valley physics.

[@swarooppalai9425]

one of the best videos on the topic I have seen so far.

[@nenoaf3104]

Great choice of intro song!!

[@huanzhao7117]

Amazing talk! Learned a lot.