Abstract
In two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs), new electronic phenomena such as tunable bandgaps1,2,3 and strongly bound excitons and trions emerge from strong many-body effects4,5,6, beyond the spin and valley degrees of freedom induced by spin–orbit coupling and by lattice symmetry7. Combining single-layer TMDs with other 2D materials in van der Waals heterostructures offers an intriguing means of controlling the electronic properties through these many-body effects, by means of engineered interlayer interactions8,9,10. Here, we use micro-focused angle-resolved photoemission spectroscopy (microARPES) and in situ surface doping to manipulate the electronic structure of single-layer WS2 on hexagonal boron nitride (WS2/h-BN). Upon electron doping, we observe an unexpected giant renormalization of the spin–orbit splitting of the single-layer WS2 valence band, from 430 meV to 660 meV, together with a bandgap reduction of at least 325 meV, attributed to the formation of trionic quasiparticles. These findings suggest that the electronic, spintronic and excitonic properties are widely tunable in 2D TMD/h-BN heterostructures, as these are intimately linked to the quasiparticle dynamics of the materials11,12,13.
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References
Chernikov, A. et al. Electrical tuning of exciton binding energies in monolayer WS2. Phys. Rev. Lett. 115, 126802 (2015).
Liang, Y. & Yang, L. Carrier plasmon induced nonlinear band gap renormalization in two-dimensional semiconductors. Phys. Rev. Lett. 114, 063001 (2015).
Chernikov, A., Ruppert, C., Hill, H., Rigosi, A. & Heinz, T. Population inversion and giant bandgap renormalization in atomically thin WS2 layers. Nat. Photon. 9, 466–470 (2015).
Ramasubramaniam, A. Large excitonic effects in monolayers of molybdenum and tungsten dichalcogenides. Phys. Rev. B 86, 115409 (2012).
Qiu, D., Jornada, F. & Louie, S. Optical spectrum of MoS2: many-body effects and diversity of exciton states. Phys. Rev. Lett. 111, 216805 (2013).
Mak, K. F. et al. Tightly bound trions in monolayer MoS2. Nat. Mater. 12, 207–211 (2013).
Xiao, D., Liu, G., Feng, W., Xu, X. & Yao, W. Coupled spin and valley physics in monolayers of MoS2 and other Group-VI dichalcogenides. Phys. Rev. Lett. 108, 196802 (2012).
Geim, A. & Grigorieva, I. Van der Waals heterostructures. Nature 499, 419–425 (2013).
Ugeda, M. et al. Giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor. Nat. Mater. 13, 1091–1095 (2014).
Larentis, S. et al. Band offset and negative compressibility in graphene–MoS2 heterostructures. Nano Lett. 14, 2039–2045 (2014).
Xu, X., Yao, W., Xiao, D. & Heinz, T. Spin and pseudospins in layered transition metal dichalcogenides. Nat. Phys. 10, 343–350 (2014).
Kormányos, A. k·p theory for two-dimensional transition metal dichalcogenide semiconductors. 2D Mater. 2, 049501 (2015).
Mak, K. F. & Shan, J. Photonics and optoelectronics of 2D semiconductor transition metal dichalcogenides. Nat. Photon. 10, 216–226 (2016).
Ferreiros, Y. & Cortijo, A. Large conduction band and Fermi velocity spin splitting due to Coulomb interactions in single-layer MoS2. Phys. Rev. B 90, 195426 (2014).
Bostwick, A., Ohta, T., Seyller, T., Horn, K. & Rotenberg, E. Quasiparticle dynamics in graphene. Nat. Phys. 3, 36–40 (2007).
Zhang, Y. et al. Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2. Nat. Nanotechnol. 9, 111–115 (2014).
Zhang, Y. et al. Electronic structure, surface doping, and optical response in epitaxial WSe2 thin films. Nano Lett. 16, 2485–2491 (2016).
Miwa, J. et al. Electronic structure of epitaxial single-layer MoS2. Phys. Rev. Lett. 114, 046802 (2015).
Jin, W. et al. Direct measurement of the thickness-dependent electronic band structure of MoS2 using angle-resolved photoemission spectroscopy. Phys. Rev. Lett. 111, 106801 (2013).
Dean, C. et al. Boron nitride substrates for high-quality graphene electronics. Nat. Nanotechnol. 5, 722–726 (2010).
Wang, L. et al. One-dimensional electrical contact to a two-dimensional material. Science 342, 614–617 (2013).
Wang, E. et al. Gaps induced by inversion symmetry breaking and second-generation Dirac cones in graphene/hexagonal boron nitride. Nat. Phys. 12, 1111–1115 (2016).
Ulstrup, S. et al. Spatially resolved electronic properties of single-layer WS2 on transition metal oxides. ACS Nano 10, 10058–10067 (2016).
Dendzik, M. et al. Growth and electronic structure of epitaxial single-layer WS2 on Au(111). Phys. Rev. B 92, 245442 (2015).
Riley, J. et al. Negative electronic compressibility and tunable spin splitting in WSe2. Nat. Nanotechnol. 10, 1043–1047 (2015).
Yuan, H. et al. Zeeman-type spin splitting controlled by an electric field. Nat. Phys. 9, 563–569 (2013).
Shanavas, K. V. & Satpathy, S. Effective tight-binding model for MX2 under electric and magnetic fields. Phys. Rev. B 91, 235145 (2015).
Kang, M. et al. Universal mechanism of band-gap engineering in transition-metal dichalcogenides. Nano Lett. 17, 1610–1615 (2017).
Zhu, B., Chen, X. & Cui, X. Exciton binding energy of monolayer WS2. Sci. Rep. 5, 9218 (2015).
Efimkin, D. K. & MacDonald, A. H. Many-body theory of trion absorption features in two-dimensional semiconductors. Phys. Rev. B 95, 035417 (2017).
Acknowledgements
We thank A. H. MacDonald for discussions. S.U. acknowledges financial support from the Danish Council for Independent Research, Natural Sciences, under the Sapere Aude programme (grant no. DFF-4090-00125) and from VILLUM FONDEN (grant no. 15375). R.J.K. is supported by a fellowship within the postdoctoral programme of the German Academic Exchange Service (DAAD). S.M. acknowledges support by the Swiss National Science Foundation (grant no. P2ELP2-155357). The work at Ohio State was primarily supported by NSF-MRSEC (grant DMR-1420451). Work at the US Naval Research Laboratory (NRL) was supported by core programmes and the NRL Nanoscience Institute, and by the Air Force Office of Scientific Research under contract number AOARD 14IOA018- 134141. This research used resources of the Advanced Light Source, which is a US Department of Energy Office of Science User Facility under contract no. DE-AC02-05CH11231.
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J.K. and S.U. conceived and planned the experiments. K.M.M. and B.T.J. synthesized the single-layer WS2 flakes on SiO2. J.K., S.S., J.X. and R.K.K. assembled the WS2/h-BN heterostructures on TiO2. S.U., R.J.K., S.M., J.K., A.B., E.R. and C.J. performed the microARPES experiments. The microARPES set-up was developed and maintained by C.J., A.B. and E.R. S.U. analysed the experimental data with inputs from C.J. and E.R. All authors contributed to the interpretation and writing of the manuscript.
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Katoch, J., Ulstrup, S., Koch, R.J. et al. Giant spin-splitting and gap renormalization driven by trions in single-layer WS2/h-BN heterostructures. Nature Phys 14, 355–359 (2018). https://doi.org/10.1038/s41567-017-0033-4
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DOI: https://doi.org/10.1038/s41567-017-0033-4
