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Journal Articles Physical Review Letters Year : 2014

Carrier and Polarization Dynamics in Monolayer MoS 2

Abstract

In monolayer MoS2, optical transitions across the direct band gap are governed by chiral selection rules, allowing optical valley initialization. In time-resolved photoluminescence (PL) experiments, we find that both the polarization and emission dynamics do not change from 4 to 300 K within our time resolution. We measure a high polarization and show that under pulsed excitation the emission polarization significantly decreases with increasing laser power. We find a fast exciton emission decay time on the order of 4 ps. The absence of a clear PL polarization decay within our time resolution suggests that the initially injected polarization dominates the steady-state PL polarization. The observed decrease of the initial polarization with increasing pump photon energy hints at a possible ultrafast intervalley relaxation beyond the experimental ps time resolution. By compensating the temperature-induced change in band gap energy with the excitation laser energy, an emission polarization of 40% is recovered at 300 K, close to the maximum emission polarization for this sample at 4 K.
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Dates and versions

hal-02050950 , version 1 (27-02-2019)

Identifiers

  • HAL Id : hal-02050950 , version 1

Cite

David Lagarde, Louis Bouet, Xavier Marie, C. Zhu, L. Liu, et al.. Carrier and Polarization Dynamics in Monolayer MoS 2. Physical Review Letters, 2014, 112 (4). ⟨hal-02050950⟩
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