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Valley-Coherent Hot Carriers and Thermal Relaxation in Monolayer Transition Metal Dichalcogenides

Kallatt, Sangeeth and Umesh, Govindarao and Majumdar, Kausik (2016) Valley-Coherent Hot Carriers and Thermal Relaxation in Monolayer Transition Metal Dichalcogenides. In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 7 (11). pp. 2032-2038.

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Official URL: http://dx.doi.org/10.1021/acs.jpclett.6600759

Abstract

We show room-temperature valley coherence in MoS2, MoSe2, WS2, and WSe2 monolayers using linear polarization-resolved hot photoluminescence (PL) at energies close to the excitation, demonstrating preservation of valley coherence before sufficient scattering events. The features of the copolarized hot luminescence allow us to extract the lower bound of the binding energy of the A exciton in monolayer MoS2 as 0.42 (+/- 0.02) eV. The broadening of the PL peak is found to be dominated by a Boltzmann-type hot luminescence tail, and using the slope of the exponential decay, the carrier temperature is extracted in situ at different stages of energy relaxation. The temperature of the emitted optical phonons during the relaxation process is probed by exploiting the corresponding broadening of the Raman peaks due to temperature induced anharmonic effects. The findings provide a physical picture of photogeneration of valley-coherent hot carriers and their subsequent energy relaxation pathways.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
Division of Interdisciplinary Research > Centre for Nano Science and Engineering
Depositing User: Id for Latest eprints
Date Deposited: 05 Jul 2016 06:42
Last Modified: 05 Jul 2016 06:42
URI: http://eprints.iisc.ac.in/id/eprint/54135

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