CUED Publications database

Charged excitons in monolayer WSe2: Experiment and theory

Courtade, E and Semina, M and Manca, M and Glazov, MM and Robert, C and Cadiz, F and Wang, G and Taniguchi, T and Watanabe, K and Pierre, M and Escoffier, W and Ivchenko, EL and Renucci, P and Marie, X and Amand, T and Urbaszek, B (2017) Charged excitons in monolayer WSe2: Experiment and theory. Physical Review B, 96. ISSN 2469-9950

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Charged excitons, or X± trions, in monolayer transition-metal dichalcogenides have binding energies of several tens of meV. Together with the neutral exciton X0 they dominate the emission spectrum at low and elevated temperatures. We use charge-tunable devices based on WSe2 monolayers encapsulated in hexagonal boron nitride to investigate the difference in binding energy between X+ and X- and the X- fine structure. We find in the charge-neutral regime, the X0 emission accompanied at lower energy by a strong peak close to the longitudinal optical (LO) phonon energy. This peak is absent in reflectivity measurements, where only the X0 and an excited state of the X0 are visible. In the n-doped regime, we find a closer correspondence between emission and reflectivity as the trion transition with a well-resolved fine-structure splitting of 6 meV for X- is observed. We present a symmetry analysis of the different X+ and X- trion states and results of the binding energy calculations. We compare the trion binding energy for the n- and p-doped regimes with our model calculations for low carrier concentrations. We demonstrate that the splitting between the X+ and X- trions as well as the fine structure of the X- state can be related to the short-range Coulomb-exchange interaction between the charge carriers.

Item Type: Article
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 15 Sep 2017 20:09
Last Modified: 15 Apr 2021 06:50
DOI: 10.1103/PhysRevB.96.085302