Room-temperature valleytronic transistor

Abstract

Valleytronics, based on the valley degree of freedom rather than charge, is a promising candidate for next-generation information devices beyond complementary metal–oxide–semiconductor (CMOS) technology1,2,3,4. Although many intriguing valleytronic properties have been explored based on excitonic injection or the non-local response of transverse current schemes at low temperature4,5,6,7, demonstrations of valleytronic building blocks similar to transistors in electronics, especially at room temperature, remain elusive. Here, we report a solid-state device that enables a full sequence of generating, propagating, detecting and manipulating valley information at room temperature. Chiral nanocrescent plasmonic antennae8 are used to selectively generate valley-polarized carriers in MoS2 through hot-electron injection under linearly polarized infrared excitation. These long-lived valley-polarized free carriers can be detected in a valley Hall configuration9,10,11 even without charge current, and can propagate over 18 μm by means of drift. In addition, electrostatic gating allows us to modulate the magnitude of the valley Hall voltage. The electrical valley Hall output could drive the valley manipulation of a cascaded stage, rendering the device able to serve as a transistor free of charge current with pure valleytronic input/output. Our results demonstrate the possibility of encoding and processing information by valley degree of freedom, and provide a universal strategy to study the Berry curvature dipole in quantum materials.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Device configuration and experimental set-up for MoS2 valleytronic transistor.
Fig. 2: Generation of the valley-polarized electrons in the valleytronic transistor.
Fig. 3: Detection and transport of valley current in the valleytronic transistor.
Fig. 4: Manipulation of valley information by electrostatic gating.

Data availability

The data that support Figs. 14 can be found in the Source Data, and the data that support the other findings of this study are available from the corresponding author upon reasonable request. Source data are provided with this paper.

References

  1. 1.

    Xiao, D., Yao, W. & Niu, Q. Valley-contrasting physics in graphene: magnetic moment and topological transport. Phys. Rev. Lett. 99, 236809 (2007).

    Article  Google Scholar 

  2. 2.

    Mak, K. F., He, K. L., Shan, J. & Heinz, T. F. Control of valley polarization in monolayer MoS2 by optical helicity. Nat. Nanotechnol. 7, 494–498 (2012).

    CAS  Article  Google Scholar 

  3. 3.

    Zhu, Z. W. et al. Field-induced polarization of Dirac valleys in bismuth. Nat. Phys. 8, 89–94 (2012).

    CAS  Article  Google Scholar 

  4. 4.

    Isberg, J. et al. Generation, transport and detection of valley-polarized electrons in diamond. Nat. Mater. 12, 760–764 (2013).

    CAS  Article  Google Scholar 

  5. 5.

    Shimazaki, Y.et al. Generation and detection of pure valley current by electrically induced Berry curvature in bilayer graphene. Nat. Phys. 11, 1032–1036 (2015).

  6. 6.

    Li, J. et al. A valley valve and electron beam splitter. Science 362, 1149–1152 (2018).

    CAS  Article  Google Scholar 

  7. 7.

    Shkolnikov, Y. P., de Poortere, E. P., Tutuc, E. & Shayegan, M. Valley splitting of AlAs two-dimensional electrons in a perpendicular magnetic field. Phys. Rev. Lett. 89, 226805 (2002).

    CAS  Article  Google Scholar 

  8. 8.

    Fang, Y. et al. Hot electron generation and cathodoluminescence nanoscopy of chiral split ring resonators. Nano Lett. 16, 5183–5190 (2016).

    CAS  Article  Google Scholar 

  9. 9.

    Mak, K. F., McGill, K. L., Park, J. & McEuen, P. L. The valley Hall effect in MoS2 transistors. Science 344, 1489–1492 (2014).

    CAS  Article  Google Scholar 

  10. 10.

    Ubrig, N. et al. Microscopic origin of the valley Hall effect in transition metal dichalcogenides revealed by wavelength-dependent mapping. Nano Lett. 17, 5719–5725 (2017).

    CAS  Article  Google Scholar 

  11. 11.

    Sui, M. et al. Gate-tunable topological valley transport in bilayer graphene. Nat. Phys. 11, 1027–1031 (2015).

    CAS  Article  Google Scholar 

  12. 12.

    Zeng, H. et al. Valley polarization in MoS2 monolayers by optical pumping. Nat. Nanotechnol. 7, 490–493 (2012).

    CAS  Article  Google Scholar 

  13. 13.

    Cao, T. et al. Valley-selective circular dichroism of monolayer molybdenum disulphide. Nat. Commun. 3, 887 (2012).

    Article  Google Scholar 

  14. 14.

    Sun, L. et al. Separation of valley excitons in a MoS2 monolayer using a subwavelength asymmetric groove array. Nat. Photonics 13, 180–184 (2019).

    CAS  Article  Google Scholar 

  15. 15.

    Yang, L. et al. Long-lived nanosecond spin relaxation and spin coherence of electrons in monolayer MoS2 and WS2. Nat. Phys. 11, 830–834 (2015).

  16. 16.

    Lee, J., Mak, K. F. & Shan, J. Electrical control of the valley Hall effect in bilayer MoS2 transistors. Nat. Nanotechnol. 11, 421–426 (2016).

    CAS  Article  Google Scholar 

  17. 17.

    Lee, J. et al. Valley magnetoelectricity in single-layer MoS2. Nat. Mater. 16, 887–891 (2017).

    CAS  Article  Google Scholar 

  18. 18.

    Zhang, Y. J. et al. Electrically switchable chiral light-emitting transistor. Science 344, 725–728 (2014).

    CAS  Article  Google Scholar 

  19. 19.

    Sanchez, O. L. et al. Valley polarization by spin injection in a light-emitting van der Waals heterojunction. Nano Lett. 16, 5792–5797 (2016).

    CAS  Article  Google Scholar 

  20. 20.

    Ye, Y. et al. Electrical generation and control of the valley carriers in a monolayer transition metal dichalcogenide. Nat. Nanotechnol. 11, 597–603 (2016).

    Article  Google Scholar 

  21. 21.

    Eginligil, M. et al. Dichroic spin–valley photocurrent in monolayer molybdenum disulphide. Nat. Commun. 6, 7636 (2015).

    Article  Google Scholar 

  22. 22.

    Cha, S. et al. Generation, transport and detection of valley-locked spin photocurrent in WSe2–graphene–Bi2Se3 heterostructures. Nat. Nanotechnol. 13, 910–914 (2018).

    CAS  Article  Google Scholar 

  23. 23.

    Yuan, H. et al. Generation and electric control of spin–valley-coupled circular photogalvanic current in WSe2. Nat. Nanotechnol. 9, 851–857 (2014).

    CAS  Article  Google Scholar 

  24. 24.

    Li, Z. et al. Tailoring MoS2 valley-polarized photoluminescence with super chiral near-field. Adv. Mater. 30, 1801908 (2018).

    Article  Google Scholar 

  25. 25.

    Wu, Z. et al. Room-temperature active modulation of valley dynamics in a monolayer semiconductor through chiral Purcell effects. Adv. Mater. 31, 1904132 (2019).

    CAS  Article  Google Scholar 

  26. 26.

    Buscema, M. et al. Large and tunable photothermoelectric effect in single-layer MoS2. Nano Lett. 13, 358–363 (2013).

    CAS  Article  Google Scholar 

  27. 27.

    Howell, S. L. et al. Investigation of band-offsets at monolayer–multilayer MoS2 junctions by scanning photocurrent microscopy. Nano Lett. 15, 2278–2284 (2015).

    CAS  Article  Google Scholar 

  28. 28.

    Jin, C. et al. Imaging of pure spin-valley diffusion current in WS2-WSe2 heterostructures. Science 360, 893–896 (2018).

    CAS  Article  Google Scholar 

  29. 29.

    McIver, J. W. et al. Control over topological insulator photocurrents with light polarization. Nat. Nanotechnol. 7, 96–100 (2012).

    CAS  Article  Google Scholar 

  30. 30.

    Lagarde, D. et al. Carrier and polarization dynamics in monolayer MoS2. Phys. Rev. Lett. 112, 047401 (2014).

    CAS  Article  Google Scholar 

  31. 31.

    Mai, C. et al. Many-body effects in valleytronics: direct measurement of valley lifetimes in single-layer MoS2. Nano Lett. 14, 202–208 (2014).

    CAS  Article  Google Scholar 

  32. 32.

    Wang, G. et al. Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2. Phys. Rev. B 90, 075413 (2014).

    Article  Google Scholar 

  33. 33.

    Singh, A. et al. Long-lived valley polarization of intravalley trions in monolayer WSe2. Phys. Rev. Lett. 117, 257402 (2016).

    Article  Google Scholar 

  34. 34.

    Rivera, P. et al. Valley-polarized exciton dynamics in a 2D semiconductor heterostructure. Science 351, 688–691 (2016).

    CAS  Article  Google Scholar 

  35. 35.

    Schaibley, J. R. et al. Valleytronics in 2D materials. Nat. Rev. Mater. 1, 16055 (2016).

    CAS  Article  Google Scholar 

  36. 36.

    Robin, O., Lei, S., Mikael, S. & Mikael, K. Continuous-gradient plasmonic nanostructures fabricated by evaporation on a partially exposed rotating substrate. Adv. Mater. 28, 4658–4664 (2016).

    Article  Google Scholar 

  37. 37.

    Ermolaev, G. A., Yakubovsky, D. I., Stebunov, Y. V., Arsenin, A. V. & Volkov, V. S. Spectral ellipsometry of monolayer transition metal dichalcogenides: analysis of excitonic peaks in dispersion. J. Vac. Sci. Technol. B 38, 014002 (2020).

    CAS  Article  Google Scholar 

  38. 38.

    Johnson, P. B. & Christy, R. W. Optical constants of the noble metals. Phys. Rev. B 6, 4370–4379 (1972).

    CAS  Article  Google Scholar 

  39. 39.

    Tang, Y. & Cohen, A. E. Optical chirality and its interaction with matter. Phys. Rev. Lett. 104, 163901 (2010).

    Article  Google Scholar 

  40. 40.

    Schäferling, M., Dregely, D., Hentschel, M. & Giessen, H. Tailoring enhanced optical chirality: design principles for chiral plasmonic nanostructures. Phys. Rev. X 2, 031010 (2012).

    Google Scholar 

Download references

Acknowledgements

This project was primarily supported by the National Key R&G Program of China (2018YFA0307300, 2018YFA0209100 and 2016YFA0200200), the National Natural Science Foundation of China (61934004, 61775092, 61674127 and 61874094), Zhejiang Natural Science Foundation (LZ17F040001), Program for High-Level Entrepreneurial and Innovative Talent Introduction of Jiangsu Province, Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB30000000), the Collaborative Innovation Center of Advanced Microstructures, the Fundamental Research Funds for the Central Universities and the Fundamental Research Funds for Zhejiang Provincial Colleges and Universities. L.S. acknowledges the financial support from the National Natural Science Foundation of China (NSAF, U1930402) and computational resources from the Beijing Computational Science Research Center. We also thank the supports from NJU micro-fabrication and integration centre, ZJU micro-nano fabrication centre and International Joint Innovation Centre, Zhejiang University, Haining campus.

Author information

Affiliations

Authors

Contributions

X.W., L.L. and L.S. conceived the project. L.L., X.L., A.G., B.Z. and K.S. fabricated and measured the devices. L.S. modelled, prepared and characterized the plasmonic nanostructures. H.W. helped in the FDTD simulation. A.G., X.L. and F.M. helped prepare materials and perform electron beam lithography. G.H. and L.Y. helped perform scanning electron microscopy. B.Z. contributed to the data processing. X.W., L.L. and Y.X. analysed the data and wrote the manuscript. X.W., Y.X. and Y.S. supervised the research. All authors discussed the obtained results.

Corresponding authors

Correspondence to Yang Xu or Xiaomu Wang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–19, Notes 1–11 and refs. 1–14.

Source data

Source Data Fig. 1

Statistical source data.

Source Data Fig. 2

Statistical source data.

Source Data Fig. 3

Statistical source data.

Source Data Fig. 4

Statistical source data.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Li, L., Shao, L., Liu, X. et al. Room-temperature valleytronic transistor. Nat. Nanotechnol. 15, 743–749 (2020). https://doi.org/10.1038/s41565-020-0727-0

Download citation

Search

Find nanotechnology articles, nanomaterial data and patents all in one place. Visit Nano by Nature Research