Seminar Hanan Dery

Rochester University

Hexcitons and oxcitons in monolayer WSe2

Hydrogen-like bound states of photoexcited electron-hole pairs in semiconductors — that is, excitons — have been a focus of considerable study for more than half a century. In undoped direct-gap semiconductors, neutral excitons comprise the photogenerated electron and hole in the conduction and valence bands (CB and VB), respectively, and typically manifest as discrete optical resonances below the free-particle band-gap energy. More interesting states arise when electron-hole (e-h) pairs are photoexcited into doped semiconductors containing a Fermi-sea of mobile carriers.In the archetypal monolayer semiconductor WSe2, the distinct ordering of spin-polarized valleys (low-energy pockets) in the CB allows for studies of not only simple neutral excitons and chargedexcitons (i.e., trions), but also more complex many-body states that are predicted at higher electron densities [1]. I will discuss magneto-optical measurements of electron-rich WSe2 monolayers [2], and interpret the spectral lines that emerge at high electron doping as optical transitions of 6-body exciton states (“hexcitons”) and 8-body exciton states (“oxcitons”). These many-body states emerge when a photoexcited electron-hole pair interacts simultaneously with multiple Fermi seas, each having distinguishable spin and valley quantum numbers

The event is finished.


Jul 12 2022




Seminar room
Build. 27, Room 2.20 (2nd floor left), INSA, 135 av. de Rangueil, Toulouse