Universität zu Köln

Kuhn, Henning, Wagner, Julian, Han, Shuangping, Bernhardt, Robin, Gao, Yan, Xiao, Liantuan, Zhu, Jingyi and van Loosdrecht, Paul H. M. ORCID: 0000-0002-3704-9890 (2020). Excitonic Transport and Intervalley Scattering Dynamics in Large-Size Exfoliated MoSe2 Monolayer Investigated by Heterodyned Transient Grating Spectroscopy. Laser Photon. Rev., 14 (12). WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 1863-8899

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Abstract

Exciton intervalley scattering, annihilation, relaxation dynamics, and diffusive transport in monolayer transition metal dichalcogenides are central to the functionality of devices based on them. Here, these properties in a large-size exfoliated high-quality monolayer MoSe2 are addressed directly using heterodyned transient grating spectroscopy at room temperature. While the free exciton population is found to be long-lived (approximate to 230 ps), an extremely fast intervalley scattering (<= 170 fs) is observed, leading to a negligible valley polarization, consistent with steady state photoluminescence measurements and theoretical calculation. The exciton population decay shows an appreciable contribution from the exciton-exciton annihilation, with an annihilation rate of approximate to 0.01 cm(2) s(-1). The annihilation process also leads to a significant distortion of the transient grating evolution. Taking this distortion into account, consistent exciton diffusion constants D approximate to 1.4 cm(2) s(-1) are found by a model simulation in the excitation density range of 10(11)-10(12) cm(-2). The presented results highlight the importance of correctly considering the many-body annihilation processes to obtain a pronounced understanding of the excitonic properties of monolayer transition metal dichalcogenides.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Kuhn, Henning UNSPECIFIED UNSPECIFIED UNSPECIFIED Wagner, Julian UNSPECIFIED UNSPECIFIED UNSPECIFIED Han, Shuangping UNSPECIFIED UNSPECIFIED UNSPECIFIED Bernhardt, Robin UNSPECIFIED UNSPECIFIED UNSPECIFIED Gao, Yan UNSPECIFIED UNSPECIFIED UNSPECIFIED Xiao, Liantuan UNSPECIFIED UNSPECIFIED UNSPECIFIED Zhu, Jingyi UNSPECIFIED UNSPECIFIED UNSPECIFIED van Loosdrecht, Paul H. M. UNSPECIFIED orcid.org/0000-0002-3704-9890 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-311365
DOI:	10.1002/lpor.202000029
Journal or Publication Title:	Laser Photon. Rev.
Volume:	14
Number:	12
Date:	2020
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	1863-8899
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics II
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language VALLEY POLARIZATION; CARRIER-DIFFUSION; ANNIHILATION; SPIN; PHOTOLUMINESCENCE; OPTOELECTRONICS; RECOMBINATION; GENERATION; LIFETIMES; BANDGAP Multiple languages Optics; Physics, Applied; Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/31136