CUED Publications database

Enabling valley selective exciton scattering in monolayer WSe 2 through upconversion

Manca, M and Glazov, MM and Robert, C and Cadiz, F and Taniguchi, T and Watanabe, K and Courtade, E and Amand, T and Renucci, P and Marie, X and Wang, G and Urbaszek, B (2017) Enabling valley selective exciton scattering in monolayer WSe 2 through upconversion. Nature Communications, 8. 14927-. ISSN 2041-1723

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Excitons, Coulomb bound electron-hole pairs, are composite bosons and their interactions in traditional semiconductors lead to condensation and light amplification. The much stronger Coulomb interaction in transition metal dichalcogenides such as WSe 2 monolayers combined with the presence of the valley degree of freedom is expected to provide new opportunities for controlling excitonic effects. But so far the bosonic character of exciton scattering processes remains largely unexplored in these two-dimensional materials. Here we show that scattering between B-excitons and A-excitons preferably happens within the same valley in momentum space. This leads to power dependent, negative polarization of the hot B-exciton emission. We use a selective upconversion technique for efficient generation of B-excitons in the presence of resonantly excited A-excitons at lower energy; we also observe the excited A-excitons state 2s. Detuning of the continuous wave, low-power laser excitation outside the A-exciton resonance (with a full width at half maximum of 4 meV) results in vanishing upconversion signal.

Item Type: Article
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 25 Jul 2017 03:51
Last Modified: 13 Apr 2021 07:45
DOI: 10.1038/ncomms14927