Twist-angle-dependent interlayer exciton diffusion in WS2–WSe2 heterobilayers
Source abstract
Abstract
The nanoscale periodic potentials introduced by moiré patterns in semiconducting van der Waals heterostructures have emerged as a platform for designing exciton superlattices. However, our understanding of the motion of excitons in moiré potentials is still limited. Here we investigated interlayer exciton dynamics and transport in WS2-WSe2 heterobilayers in time, space and momentum domains using transient absorption microscopy combined with first-principles calculations. We found that the exciton motion is modulated by twist-angle-dependent moiré potentials around 100 meV and deviates from normal diffusion due to the interplay between the moiré potentials and strong exciton-exciton interactions. Our experimental results verified the theoretical prediction of energetically favourable K-Q interlayer excitons and showed exciton-population dynamics that are controlled by the twist-angle-dependent energy difference between the K-Q and K-K excitons. These results form a basis to investigate exciton and spin transport in van der Waals heterostructures, with implications for the design of quantum communication devices.
Source: europepmc · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: 2D Materials and Applications · Perovskite Materials and Applications · Graphene research and applications
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (45)
Show source-provided references
1. Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 499, 419–425 (2013).10.1038/nature12385 ↗
2. Novoselov, K. S., Mishchenko, A., Carvalho, A. & Castro Neto, A. H. 2D materials and van der Waals heterostructures. Science 353, aac9439 (2016).10.1126/science.aac9439 ↗
3. Rivera, P. et al. Valley-polarized exciton dynamics in a 2D semiconductor heterostructure. Science 351, 688–691 (2016).10.1126/science.aac7820 ↗
4. Jin, C. et al. Imaging of pure spin-valley diffusion current in WS2/WSe2 heterostructures. Science 360, 893–896 (2018).10.1126/science.aao3503 ↗
5. Liu, Y. et al. Van der Waals heterostructures and devices. Nat. Rev. Mater. 1, 16042 (2016).10.1038/natrevmats.2016.42 ↗
6. Rivera, P. et al. Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures. Nat. Commun. 6, 6242 (2015).10.1038/ncomms7242 ↗
7. Xu, W. et al. Correlated fluorescence blinking in two-dimensional semiconductor heterostructures. Nature 541, 62–67 (2017).10.1038/nature20601 ↗
8. Nagler, P. et al. Interlayer exciton dynamics in a dichalcogenide monolayer heterostructure. 2D Mater. 4, 025112 (2017).10.1088/2053-1583/aa7352 ↗
9. Kunstmann, J. et al. Momentum-space indirect interlayer excitons in transition-metal dichalcogenide van der Waals heterostructures. Nat. Phys. 14, 801–805 (2018).10.1038/s41567-018-0123-y ↗
10. Yu, H., Liu, G.-B., Tang, J., Xu, X. & Yao, W. Moiré excitons: from programmable quantum emitter arrays to spin–orbit-coupled artificial lattices. Sci. Adv. 3, e1701696 (2017).10.1126/sciadv.1701696 ↗
11. Chien, C. C., Peotta, S. & Di Ventra, M. Quantum transport in ultracold atoms. Nat. Phys. 11, 998–1004 (2015).10.1038/nphys3531 ↗
12. Zhang, C. et al. Interlayer couplings, moiré patterns, and 2D electronic superlattices in MoS2/WSe2 hetero-bilayers. Sci. Adv. 3, e1601459 (2017).10.1126/sciadv.1601459 ↗
13. Yu, H., Liu, G.-B. & Yao, W. Brightened spin-triplet interlayer excitons and optical selection rules in van der Waals heterobilayers. 2D Mater. 5, 035021 (2018).10.1088/2053-1583/aac065 ↗
14. Tran, K. et al. Evidence for moiré excitons in van der Waals heterostructures. Nature 567, 71–75 (2019).10.1038/s41586-019-0975-z ↗
15. Seyler, K. L. et al. Signatures of moiré-trapped valley excitons in MoSe2/WSe2 heterobilayers. Nature 567, 66–70 (2019).10.1038/s41586-019-0957-1 ↗
16. Jin, C. et al. Observation of moiré excitons in WSe2/WS2 heterostructure superlattices. Nature 567, 76–80 (2019).10.1038/s41586-019-0976-y ↗
17. Alexeev, E. M. et al. Resonantly hybridized excitons in moiré superlattices in van der Waals heterostructures. Nature 567, 81–86 (2019).10.1038/s41586-019-0986-9 ↗
18. Zhang, N. et al. Moiré intralayer excitons in a MoSe2/MoS2 heterostructure. Nano Lett. 18, 7651–7657 (2018).10.1021/acs.nanolett.8b03266 ↗
19. Ciarrocchi, A. et al. Polarization switching and electrical control of interlayer excitons in two-dimensional van der Waals heterostructures. Nat. Photon. 13, 131–136 (2019).10.1038/s41566-018-0325-y ↗
20. Unuchek, D. et al. Room-temperature electrical control of exciton flux in a van der Waals heterostructure. Nature 560, 340–344 (2018).10.1038/s41586-018-0357-y ↗
21. Jauregui, L. A. et al. Electrical control of interlayer exciton dynamics in atomically thin heterostructures. Science 366, 870–875 (2019).10.1126/science.aaw4194 ↗
22. Snoke, D., Denev, S., Liu, Y., Pfeiffer, L. & West, K. Long-range transport in excitonic dark states in coupled quantum wells. Nature 418, 754–757 (2002).10.1038/nature00940 ↗
23. High, A. A., Novitskaya, E. E., Butov, L. V., Hanson, M. & Gossard, A. C. Control of exciton fluxes in an excitonic integrated circuit. Science 321, 229–231 (2008).10.1126/science.1157845 ↗
24. Vögele, X. P., Schuh, D., Wegscheider, W., Kotthaus, J. P. & Holleitner, A. W. Density enhanced diffusion of dipolar excitons within a one-dimensional channel. Phys. Rev. Lett. 103, 126402 (2009).10.1103/PhysRevLett.103.126402 ↗
25. Liu, F., Li, Q. & Zhu, X. Direct determination of momentum resolved electron transfer in the photo-excited MoS2/WS2 van der Waals heterobilayer by TR-ARPES. Preprint at https://arxiv.org/abs/1909.07759 (2019).10.15278/isms.2020.RA04 ↗
26. Gillen, R. & Maultzsch, J. Interlayer excitons in MoSe2/WSe2 heterostructures from first principles. Phys. Rev. B 97, 165306 (2018).10.1103/PhysRevB.97.165306 ↗
27. Yoo, Y., Degregorio, Z. P. & Johns, J. E. Seed crystal homogeneity controls lateral and vertical heteroepitaxy of monolayer MoS2 and WS2. J. Am. Chem. Soc. 137, 14281–14287 (2015).10.1021/jacs.5b06643 ↗
28. Kang, J., Tongay, S., Zhou, J., Li, J. & Wu, J. Band offsets and heterostructures of two-dimensional semiconductors. Appl. Phys. Lett. 102, 012111 (2013).10.1063/1.4774090 ↗
29. Zheng, B. et al. Band alignment engineering in two-dimensional lateral heterostructures. J. Am. Chem. Soc. 140, 11193–11197 (2018).10.1021/jacs.8b07401 ↗
30. Guo, Z. et al. Long-range hot-carrier transport in hybrid perovskites visualized by ultrafast microscopy. Science 356, 59–62 (2017).10.1126/science.aam7744 ↗
31. Zhu, T. et al. Highly mobile charge-transfer excitons in two-dimensional WS2/tetracene heterostructures. Sci. Adv. 4, eaao3104 (2018).10.1126/sciadv.aao3104 ↗
32. Hill, H. M. et al. Exciton broadening in WS2/graphene heterostructures. Phys. Rev. B 96, 205401 (2017).10.1103/PhysRevB.96.205401 ↗
33. Unuchek, D. et al. Valley-polarized exciton currents in a van der Waals heterostructure. Nat. Nanotechnol. 14, 1104–1109 (2019).10.1038/s41565-019-0559-y ↗
34. Laikhtman, B. & Rapaport, R. Exciton correlations in coupled quantum wells and their luminescence blue shift. Phys. Rev. B 80, 195313 (2009).10.1103/PhysRevB.80.195313 ↗
35. Kulig, M. et al. Exciton diffusion and halo effects in monolayer semiconductors. Phys. Rev. Lett. 120, 207401 (2018).10.1103/PhysRevLett.120.207401 ↗
36. Glazov, M. M. Phonon wind and drag of excitons in monolayer semiconductors. Phys. Rev. B 100, 193 (2019).
37. Ivanov, A. L. Quantum diffusion of dipole-oriented indirect excitons in coupled quantum wells. Europhys. Lett. 59, 586–591 (2002).10.1209/epl/i2002-00144-3 ↗
38. Shahnazaryan, V., Iorsh, I., Shelykh, I. A. & Kyriienko, O. Exciton–exciton interaction in transition-metal dichalcogenide monolayers. Phys. Rev. B 96, 115409 (2017).10.1103/PhysRevB.96.115409 ↗
39. Merkl, P. et al. Ultrafast transition between exciton phases in van der Waals heterostructures. Nat. Mater. 18, 691–696 (2019).10.1038/s41563-019-0337-0 ↗
40. Wang, J. et al. Excitonic phase transitions in MoSe2/WSe2 heterobilayers. Preprint at https://arxiv.org/abs/2001.03812 (2020).
41. Yuan, L. et al. Photocarrier generation from interlayer charge-transfer transitions in WS2-graphene heterostructures. Sci. Adv. 4, e1700324 (2018).10.1126/sciadv.1700324 ↗
42. te Velde, G. & Baerends, E. J. Precise density-functional method for periodic structures. Phys. Rev. B 44, 7888–7903 (1991).10.1103/PhysRevB.44.7888 ↗
43. Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).10.1103/PhysRevLett.77.3865 ↗
44. Philipsen, P. H. T., van Lenthe, E., Snijders, J. G. & Baerends, E. J. Relativistic calculations on the adsorption of CO on the (111) surfaces of Ni, Pd, and Pt within the zeroth-order regular approximation. Phys. Rev. B 56, 13556–13562 (1997).10.1103/PhysRevB.56.13556 ↗
45. Grimme, S., Ehrlich, S. & Goerigk, L. Effect of the damping function in dispersion corrected density functional theory. J. Comput. Chem. 32, 1456–1465 (2011).10.1002/jcc.21759 ↗