Probing Critical Point Energies of Transition Metal Dichalcogenides: Surprising Indirect Gap of Single Layer WSe 2
Mende, Patrick C.
Feenstra, Randall M.
Shih, Chih Kang
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
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AbstractBy using a comprehensive form of scanning tunneling spectroscopy, we have revealed detailed quasi-particle electronic structures in transition metal dichalcogenides, including the quasi-particle gaps, critical point energy locations, and their origins in the Brillouin zones. We show that single layer WSe surprisingly has an indirect quasi-particle gap with the conduction band minimum located at the Q-point (instead of K), albeit the two states are nearly degenerate. We have further observed rich quasi-particle electronic structures of transition metal dichalcogenides as a function of atomic structures and spin-orbit couplings. Such a local probe for detailed electronic structures in conduction and valence bands will be ideal to investigate how electronic structures of transition metal dichalcogenides are influenced by variations of local environment.
CitationZhang C, Chen Y, Johnson A, Li M-Y, Li L-J, et al. (2015) Probing Critical Point Energies of Transition Metal Dichalcogenides: Surprising Indirect Gap of Single Layer WSe2. Nano Letters 15: 6494–6500. Available: http://dx.doi.org/10.1021/acs.nanolett.5b01968.
SponsorsThis research was supported with grants from the Welch Foundation (F-1672), and the U.S. National Science Foundation (DMR-1306878 and DMR-1205275). L.J.L. thanks the support from Academia Sinica Taiwan, AOARD-134137 U.S.A. and KAUST, Saudi Arabia. C.K.S also thanks the partially supported by the NT 3.0 Program, Ministry of Education, Taiwan for a visitng professorship at the National Tsing-Hua University. We also thank useful discussions with Professor Wang Yao of Hong Kong University.
PublisherAmerican Chemical Society (ACS)
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