Probing Photoexcited Carriers in a Few-Layer MoS2 Laminate by Time-Resolved Optical Pump-Terahertz Probe Spectroscopy

Kar, Srabani and Su, Y and Nair, RR and Sood, AK (2015) Probing Photoexcited Carriers in a Few-Layer MoS2 Laminate by Time-Resolved Optical Pump-Terahertz Probe Spectroscopy. In: ACS NANO, 9 (12). pp. 12004-12010.

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Abstract

We report the dynamics of photoinduced carriers in a free-standing MoS2 laminate consisting of a few layers (1-6 layers) using time-resolved optical pump-terahertz probe spectroscopy. Upon photoexcitation with the 800 nm pump pulse, the terahertz conductivity increases due to absorption by the photoinduced charge carriers. The relaxation of the non-equilibrium carriers shows fast as well as slow decay channels, analyzed using a rate equation model incorporating defect-assisted Auger scattering of photoexcited electrons, holes, and excitons. The fast relaxation time occurs due to the capture of electrons and holes by defects via Auger processes, resulting in nonradiative recombination. The slower relaxation arises since the excitons are bound to the defects, preventing the defect-assisted Auger recombination of the electrons and the holes. Our results provide a comprehensive understanding of the non-equilibrium carrier kinetics in a system of unscreened Coulomb interactions, where defect-assisted Auger processes dominate and should be applicable to other 2D systems.

Item Type:	Journal Article
Publication:	ACS NANO
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Keywords:	few-layer MoS2; defect-assisted Auger scattering; bound excitons; optical pump-terahertz probe
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	28 Jan 2016 07:15
Last Modified:	23 Oct 2018 14:45
URI:	http://eprints.iisc.ac.in/id/eprint/53180

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