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Title: Determination of band offsets, hybridization, and exciton binding in 2D semiconductor heterostructures

Abstract

Combining monolayers of different two-dimensional semiconductors into heterostructures creates new phenomena and device possibilities. Understanding and exploiting these phenomena hinge on knowing the electronic structure and the properties of interlayer excitations. Here, we determine the key unknown parameters in MoSe2/WSe2 heterobilayers by using rational device design and submicrometer angle-resolved photoemission spectroscopy (μ-ARPES) in combination with photoluminescence. We find that the bands in the K-point valleys are weakly hybridized, with a valence band offset of 300 meV, implying type II band alignment. We deduce that the binding energy of interlayer excitons is more than 200 meV, an order of magnitude higher than that in analogous GaAs structures. Hybridization strongly modifies the bands at Γ, but the valence band edge remains at the K points. We also find that the spectrum of a rotationally aligned heterobilayer reflects a mixture of commensurate and incommensurate domains. These results directly answer many outstanding questions about the electronic nature of MoSe2/WSe2 heterobilayers and demonstrate a practical approach for high spectral resolution in ARPES of device-scale structures.

Authors:
 [1]; ORCiD logo [2];  [2]; ORCiD logo [2]; ORCiD logo [1];  [1];  [3];  [4]; ORCiD logo [5]; ORCiD logo [1];  [6];  [2]
  1. Univ. of Warwick, Coventry (United Kingdom). Dept. of Physics
  2. Univ. of Washington, Seattle, WA (United States). Dept. of Physics
  3. Univ. of Cambridge (United Kingdom). Cavendish Lab.
  4. Elettra-Sincrotrone Trieste S.C.p.A., Trieste (Italy)
  5. Elettra-Sincrotrone Trieste S.C.p.A., Trieste (Italy); Univ. of Trieste (Italy). Physics Dept.
  6. Univ. of Washington, Seattle, WA (United States). Dept. of Physics; Univ. of Washington, Seattle, WA (United States). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Univ. of Washington, Seattle, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1463890
Grant/Contract Number:  
SC0002197; SC0008145; SC0012509
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Science Advances
Additional Journal Information:
Journal Volume: 3; Journal Issue: 2; Journal ID: ISSN 2375-2548
Publisher:
AAAS
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; μ-ARPES; photoluminescence; linear-scaling DFT; 2D semiconductor; Graphene; heterobilay; erelectronic properties; band hybridization; commensuration

Citation Formats

Wilson, Neil R., Nguyen, Paul V., Seyler, Kyle, Rivera, Pasqual, Marsden, Alexander J., Laker, Zachary P. L., Constantinescu, Gabriel C., Kandyba, Viktor, Barinov, Alexei, Hine, Nicholas D. M., Xu, Xiaodong, and Cobden, David H. Determination of band offsets, hybridization, and exciton binding in 2D semiconductor heterostructures. United States: N. p., 2017. Web. doi:10.1126/sciadv.1601832.
Wilson, Neil R., Nguyen, Paul V., Seyler, Kyle, Rivera, Pasqual, Marsden, Alexander J., Laker, Zachary P. L., Constantinescu, Gabriel C., Kandyba, Viktor, Barinov, Alexei, Hine, Nicholas D. M., Xu, Xiaodong, & Cobden, David H. Determination of band offsets, hybridization, and exciton binding in 2D semiconductor heterostructures. United States. doi:10.1126/sciadv.1601832.
Wilson, Neil R., Nguyen, Paul V., Seyler, Kyle, Rivera, Pasqual, Marsden, Alexander J., Laker, Zachary P. L., Constantinescu, Gabriel C., Kandyba, Viktor, Barinov, Alexei, Hine, Nicholas D. M., Xu, Xiaodong, and Cobden, David H. Wed . "Determination of band offsets, hybridization, and exciton binding in 2D semiconductor heterostructures". United States. doi:10.1126/sciadv.1601832. https://www.osti.gov/servlets/purl/1463890.
@article{osti_1463890,
title = {Determination of band offsets, hybridization, and exciton binding in 2D semiconductor heterostructures},
author = {Wilson, Neil R. and Nguyen, Paul V. and Seyler, Kyle and Rivera, Pasqual and Marsden, Alexander J. and Laker, Zachary P. L. and Constantinescu, Gabriel C. and Kandyba, Viktor and Barinov, Alexei and Hine, Nicholas D. M. and Xu, Xiaodong and Cobden, David H.},
abstractNote = {Combining monolayers of different two-dimensional semiconductors into heterostructures creates new phenomena and device possibilities. Understanding and exploiting these phenomena hinge on knowing the electronic structure and the properties of interlayer excitations. Here, we determine the key unknown parameters in MoSe2/WSe2 heterobilayers by using rational device design and submicrometer angle-resolved photoemission spectroscopy (μ-ARPES) in combination with photoluminescence. We find that the bands in the K-point valleys are weakly hybridized, with a valence band offset of 300 meV, implying type II band alignment. We deduce that the binding energy of interlayer excitons is more than 200 meV, an order of magnitude higher than that in analogous GaAs structures. Hybridization strongly modifies the bands at Γ, but the valence band edge remains at the K points. We also find that the spectrum of a rotationally aligned heterobilayer reflects a mixture of commensurate and incommensurate domains. These results directly answer many outstanding questions about the electronic nature of MoSe2/WSe2 heterobilayers and demonstrate a practical approach for high spectral resolution in ARPES of device-scale structures.},
doi = {10.1126/sciadv.1601832},
journal = {Science Advances},
number = 2,
volume = 3,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}

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Works referenced in this record:

Lateral heterojunctions within monolayer MoSe2–WSe2 semiconductors
journal, August 2014

  • Huang, Chunming; Wu, Sanfeng; Sanchez, Ana M.
  • Nature Materials, Vol. 13, Issue 12, p. 1096-1101
  • DOI: 10.1038/nmat4064