Enabling valley selective exciton scattering in monolayer WSe2 through upconversion - INSA Toulouse - Institut National des Sciences Appliquées de Toulouse Access content directly
Journal Articles Nature Communications Year : 2017

Enabling valley selective exciton scattering in monolayer WSe2 through upconversion

M. Glazov
K. Watanabe
Thierry Amand

Abstract

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 WSe2 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.
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Dates and versions

hal-02056564 , version 1 (04-03-2019)

Identifiers

  • HAL Id : hal-02056564 , version 1

Cite

Marco Manca, M. Glazov, Cédric Robert, Fabian Cadiz, T. Taniguchi, et al.. Enabling valley selective exciton scattering in monolayer WSe2 through upconversion. Nature Communications, 2017, 8, pp.14927. ⟨hal-02056564⟩
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