Broadband transient THz conductivity of the transition-metal dichalcogenide MoS2

J. H. Buss; R. P. Smith; G. Coslovich; R. A. Kaindl

doi:10.1117/12.2080748

Broadband transient THz conductivity of the transition-metal dichalcogenide MoS₂

J. H. Buss, R. P. Smith, G. Coslovich, R. A. Kaindl

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

7 Scopus citations

Abstract

The transient dynamics of transition-metal dichalcogenides is of significant interest for clarifying fundamental manyparticle interactions at the nanoscale as well as for novel applications. We report an ultrafast terahertz study up to 7 THz of the lamellar semiconductor MoS₂ to access the non-equilibrium conductivity of photo-excited indirect e-h pairs in this multi-layered parent compound. While the equilibrium transport is Drude-like, near-IR optical excitation results in a complex photo-induced conductivity that consists of two components. Mobile charge carriers dominate the low frequency response below 2 THz, while at low temperatures an additional excess conductivity is observed that is enhanced around 4 THz. Two time scales appear in the dynamics: a slow ns relaxation due to non-radiative recombination and a faster sub-100 ps decay connected to the high-frequency THz feature. We discuss the broad THz peak within a model of intra-excitonic transitions in MoS₂. It agrees well with the expected binding energy and oscillator strength, yet results in an anomalous temperature dependence of the exciton fraction requiring an electronically inhomogeneous phase.

Original language	English (US)
Title of host publication	Ultrafast Phenomena and Nanophotonics XIX
Editors	Markus Betz, Abdulhakem Y. Elezzabi, Kong-Thon Tsen
Publisher	SPIE
ISBN (Electronic)	9781628414516
DOIs	https://doi.org/10.1117/12.2080748
State	Published - 2015
Externally published	Yes
Event	Ultrafast Phenomena and Nanophotonics XIX - San Francisco, United States Duration: Feb 8 2015 → Feb 11 2015

Publication series

Name	Proceedings of SPIE - The International Society for Optical Engineering
Volume	9361
ISSN (Print)	0277-786X
ISSN (Electronic)	1996-756X

Conference

Conference	Ultrafast Phenomena and Nanophotonics XIX
Country/Territory	United States
City	San Francisco
Period	2/8/15 → 2/11/15

Keywords

MoS
THz spectroscopy
electron-hole pairs
many-particle interactions
molybdenum disulfide
non-equilibrium charge transport
transition-metal dichalcogenides
ultrafast dynamics

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Computer Science Applications
Applied Mathematics
Electrical and Electronic Engineering

Access to Document

10.1117/12.2080748

Cite this

Buss, J. H., Smith, R. P., Coslovich, G., & Kaindl, R. A. (2015). Broadband transient THz conductivity of the transition-metal dichalcogenide MoS₂. In M. Betz, A. Y. Elezzabi, & K.-T. Tsen (Eds.), Ultrafast Phenomena and Nanophotonics XIX Article 93611J (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9361). SPIE. https://doi.org/10.1117/12.2080748

Broadband transient THz conductivity of the transition-metal dichalcogenide MoS₂. / Buss, J. H.; Smith, R. P.; Coslovich, G. et al.
Ultrafast Phenomena and Nanophotonics XIX. ed. / Markus Betz; Abdulhakem Y. Elezzabi; Kong-Thon Tsen. SPIE, 2015. 93611J (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9361).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Buss, JH, Smith, RP, Coslovich, G & Kaindl, RA 2015, Broadband transient THz conductivity of the transition-metal dichalcogenide MoS₂. in M Betz, AY Elezzabi & K-T Tsen (eds), Ultrafast Phenomena and Nanophotonics XIX., 93611J, Proceedings of SPIE - The International Society for Optical Engineering, vol. 9361, SPIE, Ultrafast Phenomena and Nanophotonics XIX, San Francisco, United States, 2/8/15. https://doi.org/10.1117/12.2080748

@inproceedings{b6ea3fc5a1744401960c4ab7d4856c12,

title = "Broadband transient THz conductivity of the transition-metal dichalcogenide MoS2",

abstract = "The transient dynamics of transition-metal dichalcogenides is of significant interest for clarifying fundamental manyparticle interactions at the nanoscale as well as for novel applications. We report an ultrafast terahertz study up to 7 THz of the lamellar semiconductor MoS2 to access the non-equilibrium conductivity of photo-excited indirect e-h pairs in this multi-layered parent compound. While the equilibrium transport is Drude-like, near-IR optical excitation results in a complex photo-induced conductivity that consists of two components. Mobile charge carriers dominate the low frequency response below 2 THz, while at low temperatures an additional excess conductivity is observed that is enhanced around 4 THz. Two time scales appear in the dynamics: a slow ns relaxation due to non-radiative recombination and a faster sub-100 ps decay connected to the high-frequency THz feature. We discuss the broad THz peak within a model of intra-excitonic transitions in MoS2. It agrees well with the expected binding energy and oscillator strength, yet results in an anomalous temperature dependence of the exciton fraction requiring an electronically inhomogeneous phase.",

keywords = "MoS, THz spectroscopy, electron-hole pairs, many-particle interactions, molybdenum disulfide, non-equilibrium charge transport, transition-metal dichalcogenides, ultrafast dynamics",

author = "Buss, {J. H.} and Smith, {R. P.} and G. Coslovich and Kaindl, {R. A.}",

note = "Publisher Copyright: {\textcopyright} 2015 SPIE.; Ultrafast Phenomena and Nanophotonics XIX ; Conference date: 08-02-2015 Through 11-02-2015",

year = "2015",

doi = "10.1117/12.2080748",

language = "English (US)",

series = "Proceedings of SPIE - The International Society for Optical Engineering",

publisher = "SPIE",

editor = "Markus Betz and Elezzabi, {Abdulhakem Y.} and Kong-Thon Tsen",

booktitle = "Ultrafast Phenomena and Nanophotonics XIX",

}

TY - GEN

T1 - Broadband transient THz conductivity of the transition-metal dichalcogenide MoS2

AU - Buss, J. H.

AU - Smith, R. P.

AU - Coslovich, G.

AU - Kaindl, R. A.

PY - 2015

Y1 - 2015

N2 - The transient dynamics of transition-metal dichalcogenides is of significant interest for clarifying fundamental manyparticle interactions at the nanoscale as well as for novel applications. We report an ultrafast terahertz study up to 7 THz of the lamellar semiconductor MoS2 to access the non-equilibrium conductivity of photo-excited indirect e-h pairs in this multi-layered parent compound. While the equilibrium transport is Drude-like, near-IR optical excitation results in a complex photo-induced conductivity that consists of two components. Mobile charge carriers dominate the low frequency response below 2 THz, while at low temperatures an additional excess conductivity is observed that is enhanced around 4 THz. Two time scales appear in the dynamics: a slow ns relaxation due to non-radiative recombination and a faster sub-100 ps decay connected to the high-frequency THz feature. We discuss the broad THz peak within a model of intra-excitonic transitions in MoS2. It agrees well with the expected binding energy and oscillator strength, yet results in an anomalous temperature dependence of the exciton fraction requiring an electronically inhomogeneous phase.

AB - The transient dynamics of transition-metal dichalcogenides is of significant interest for clarifying fundamental manyparticle interactions at the nanoscale as well as for novel applications. We report an ultrafast terahertz study up to 7 THz of the lamellar semiconductor MoS2 to access the non-equilibrium conductivity of photo-excited indirect e-h pairs in this multi-layered parent compound. While the equilibrium transport is Drude-like, near-IR optical excitation results in a complex photo-induced conductivity that consists of two components. Mobile charge carriers dominate the low frequency response below 2 THz, while at low temperatures an additional excess conductivity is observed that is enhanced around 4 THz. Two time scales appear in the dynamics: a slow ns relaxation due to non-radiative recombination and a faster sub-100 ps decay connected to the high-frequency THz feature. We discuss the broad THz peak within a model of intra-excitonic transitions in MoS2. It agrees well with the expected binding energy and oscillator strength, yet results in an anomalous temperature dependence of the exciton fraction requiring an electronically inhomogeneous phase.

KW - MoS

KW - THz spectroscopy

KW - electron-hole pairs

KW - many-particle interactions

KW - molybdenum disulfide

KW - non-equilibrium charge transport

KW - transition-metal dichalcogenides

KW - ultrafast dynamics

UR - http://www.scopus.com/inward/record.url?scp=84931857716&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84931857716&partnerID=8YFLogxK

U2 - 10.1117/12.2080748

DO - 10.1117/12.2080748

M3 - Conference contribution

AN - SCOPUS:84931857716

T3 - Proceedings of SPIE - The International Society for Optical Engineering

BT - Ultrafast Phenomena and Nanophotonics XIX

A2 - Betz, Markus

A2 - Elezzabi, Abdulhakem Y.

A2 - Tsen, Kong-Thon

PB - SPIE

T2 - Ultrafast Phenomena and Nanophotonics XIX

Y2 - 8 February 2015 through 11 February 2015

ER -