Role of defects and phonons in bandgap dynamics of monolayer WS2 at high carrier densities
AffiliationDepartment of Physics, University of Arizona
College of Optical Sciences, University of Arizona
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PublisherIOP Publishing Ltd
CitationBrasington, A., Golla, D., Dave, A., Chen, B., Tongay, S., Schaibley, J., ... & Sandhu, A. (2020). Role of defects and phonons in bandgap dynamics of monolayer WS2 at high carrier densities. Journal of Physics: Materials, 4(1), 015005.
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AbstractWe conduct ultrafast pump-probe spectroscopy in monolayer WS2 at high pump fluences to gain direct insight into interactions between a high density of carriers, defects, and phonons. We find that defects in the lattice play a major role in determining the relaxation dynamics by trapping the photoexcited carriers and acting as non-radiative recombination centers that emit phonons. In the high carrier density regime explored in our experiments, we observe substantial changes in the transient absorbance signal at unexpectedly long-time delays which we attribute to phonon-induced band gap modification. Our probe frequency dependent measurements and modeling indicate a renormalization of the bandgap by up to 23 meV. These results highlight the importance of defects and phonons for optical applications of monolayer transition metal dichalcogenides. © 2020 The Author(s). Published by IOP Publishing Ltd
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Except where otherwise noted, this item's license is described as Copyright © 2020 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.