Observation of ultrafast free carrier dynamics in single layer MoS2
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The dynamics of excited electrons and holes in single layer (SL) MoS2 have so far been difficult to disentangle from the excitons that dominate the optical response of this material. Here, we use time- and angle-resolved photoemission spectroscopy for an SL of MoS2 on a metallic substrate to directly measure the excited free carriers. This allows us to ascertain a direct quasiparticle band gap of 1.95 eV and determine an ultrafast (50 fs) extraction of excited free carriers via the metal in contact with the SL MoS2. This process is of key importance for optoelectronic applications that rely on separated free carriers rather than excitons.
Cabo , A , Miwa , J , Grønborg , S , Riley , J M , Johannsen , J , Cacho , C , Alexander , O , Chapman , R , Springate , E , Grioni , M , Lauritsen , J , King , P , Hofmann , P & Ulstrup , S 2015 , ' Observation of ultrafast free carrier dynamics in single layer MoS 2 ' Nano Letters , vol 15 , no. 9 , pp. 5883–5887 . DOI: 10.1021/acs.nanolett.5b01967
Copyright © 2015 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see [insert ACS Articles on Request author-directed link to Published Work, see https://dx.doi.org/10.1021/acs.nanolett.5b01967
The authors gratefully acknowledge funding from the VILLUM foundation, the Lundbeck foundation, Haldor Topsøe A/S, the Danish Strategic Research Council (CAT-C), EPSRC (Grant Nos. EP/I031014/1 and EP/L505079/1), The Royal Society, and the Swiss National Science Foundation (NSF). Ph.H. and S.U. acknowledge financial support from the Danish Council for Independent Research, Natural Sciences under the Sapere Aude program (Grant Nos. DFF-4002-00029 and DFF-4090-00125). Date of Accepted 19/08/2015
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