The Role of Electronic and Phononic Excitation in the Optical Response of Monolayer WS2 after Ultrafast Excitation

Claudia Ruppert; Alexey Chernikov; Heather M Hill; Albert F Rigosi; Tony F Heinz

doi:10.1021/acs.nanolett.6b03513

The Role of Electronic and Phononic Excitation in the Optical Response of Monolayer WS₂ after Ultrafast Excitation

Nano Lett. 2017 Feb 8;17(2):644-651. doi: 10.1021/acs.nanolett.6b03513. Epub 2017 Jan 11.

Authors

Claudia Ruppert^{1

2}, Alexey Chernikov^{1

3}, Heather M Hill^{1

4

5}, Albert F Rigosi^{1

4

5}, Tony F Heinz^{1

4

5}

Affiliations

¹ Departments of Physics and Electrical Engineering, Columbia University , New York, New York 10027, United States.
² Department of Physics, Technische Universität Dortmund , Dortmund 44227, Germany.
³ Department of Physics, University of Regensburg , Regensburg 93053, Germany.
⁴ Department of Applied Physics, Stanford University , Stanford, California 94305, United States.
⁵ SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.

PMID: 28059520
DOI: 10.1021/acs.nanolett.6b03513

Abstract

Transient changes of the optical response of WS₂ monolayers are studied by femtosecond broadband pump-probe spectroscopy. Time-dependent absorption spectra are analyzed by tracking the line width broadening, bleaching, and energy shift of the main exciton resonance as a function of time delay after the excitation. Two main sources for the pump-induced changes of the optical response are identified. Specifically, we find an interplay between modifications induced by many-body interactions from photoexcited carriers and by the subsequent transfer of the excitation to the phonon system followed by cooling of the material through the heat transfer to the substrate.

Keywords: Atomically thin 2D materials; carrier and phonon dynamics; ultrafast spectroscopy.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Letter
Research Support, Non-U.S. Gov't