Skip to main content
SpringerLink
Log in

Effect of Phonons on Valley Depolarization in Monolayer WSe2

  • Published:
Electronic Materials Letters Aims and scope Submit manuscript

Abstract

In this paper, temperature dependence of the excitonic bands in a mechanically exfoliated tungsten diselenide (WSe2) monolayer is studied using photoluminescence and circular dichroic photoluminescence (PL) in the temperature range between 8 and 300 K. The peak energies associated with the neutral exciton (A), charged exciton (trion) and localized excitons are extracted from the PL spectra revealing a trion binding energy of around 30 meV. The circular dichroic PL measured at 8 K shows about 45% valley polarisation that sharply reduces with increasing temperature to 5% at 300 K with photoexcitation energy of 1.96 eV. A detailed analysis of the emission line-width suggests that the rapid decrease of valley polarisation with the increase of temperature is caused by the strong exciton–phonon interactions which efficiently scatter the excitons into different excitonic states that are easily accessible due to the supply of excess photoexcitation energy. The emission line-width broadening with the increase of temperature indicate residual exciton dephasing lifetime < 100 fs, that correlates with the observed rapid valley depolarisation.

Graphical Abstract

Circular dichroic photoluminescence spectra in monolayer WSe2 and the influence of temperature on valley depolarization is shown.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5

Similar content being viewed by others

References

  1. Mak, K.F., Lee, C., Hone, J., Shan, J., Heinz, T.F.: Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105(13), 136805 (2010)

    Article  Google Scholar 

  2. Yan, T., Qiao, X., Liu, X., Tan, P., Zhang, X.: Photoluminescence properties and exciton dynamics in monolayer WSe2. Appl. Phys. Lett. 105(10), 101901 (2014). https://doi.org/10.1063/1.4895471

    Article  Google Scholar 

  3. Zhao, W., Ghorannevis, Z., Chu, L., Toh, M., Kloc, C., Tan, P.-H., Eda, G.: Evolution of electronic structure in atomically thin sheets of WS2 and WSe2. ACS Nano 7(1), 791–797 (2013). https://doi.org/10.1021/nn305275h

    Article  Google Scholar 

  4. Liu, G.-B., Shan, W.-Y., Yao, Y., Yao, W., Xiao, D.: Three-band tight-binding model for monolayers of group-VIB transition metal dichalcogenides. Phys. Rev. B 88(8), 085433 (2013)

    Article  Google Scholar 

  5. Riley, J.M., Mazzola, F., Dendzik, M., Michiardi, M., Takayama, T., Bawden, L., Granerød, C., Leandersson, M., Balasubramanian, T., Hoesch, M., Kim, T.K., Takagi, H., Meevasana, W., Hofmann, P., Bahramy, M.S., Wells, J.W., King, P.D.C.: Direct observation of spin-polarized bulk bands in an inversion-symmetric semiconductor. Nat. Phys. 10, 835 (2014). https://doi.org/10.1038/nphys3105

    Article  Google Scholar 

  6. Wu, S., Ross, J.S., Liu, G.-B., Aivazian, G., Jones, A., Fei, Z., Zhu, W., Xiao, D., Yao, W., Cobden, D., Xu, X.: Electrical tuning of valley magnetic moment through symmetry control in bilayer MoS2. Nat. Phys. 9, 149 (2013). https://doi.org/10.1038/nphys2524

    Article  Google Scholar 

  7. Gong, Z., Liu, G.-B., Yu, H., Xiao, D., Cui, X., Xu, X., Yao, W.: Magnetoelectric effects and valley-controlled spin quantum gates in transition metal dichalcogenide bilayers. Nat. Commun. 4, 2053 (2013). https://doi.org/10.1038/ncomms3053

    Article  Google Scholar 

  8. Li, X., Zhang, F., Niu, Q.: Unconventional quantum hall effect and tunable spin hall effect in dirac materials: application to an Isolated MoS2 Trilayer. Phys. Rev. Lett. 110(6), 066803 (2013)

    Article  Google Scholar 

  9. Sie, E.J., McIver, J.W., Lee, Y.-H., Fu, L., Kong, J., Gedik, N.: Valley-selective optical stark effect in monolayer WS2. Nat. Mater. 14, 290 (2014). https://doi.org/10.1038/nmat4156

    Article  Google Scholar 

  10. Cao, T., Wang, G., Han, W., Ye, H., Zhu, C., Shi, J., Niu, Q., Tan, P., Wang, E., Liu, B., Feng, J.: Valley-selective circular dichroism of monolayer molybdenum disulphide. Nat. Commun. 3, 887 (2012). https://doi.org/10.1038/ncomms1882

    Article  Google Scholar 

  11. Sallen, G., Bouet, L., Marie, X., Wang, G., Zhu, C.R., Han, W.P., Lu, Y., Tan, P.H., Amand, T., Liu, B.L., Urbaszek, B.: Robust optical emission polarization in MoS2 monolayers through selective valley excitation. Phys. Rev. B 86(8), 081301 (2012)

    Article  Google Scholar 

  12. Zeng, H., Dai, J., Yao, W., Xiao, D., Cui, X.: Valley polarization in MoS2 monolayers by optical pumping. Nat. Nanotechnol. 7, 490 (2012). https://doi.org/10.1038/nnano.2012.95

    Article  Google Scholar 

  13. Jones, A.M., Yu, H., Ghimire, N.J., Wu, S., Aivazian, G., Ross, J.S., Zhao, B., Yan, J., Mandrus, D.G., Xiao, D., Yao, W., Xu, X.: Optical generation of excitonic valley coherence in monolayer WSe2. Nat. Nanotechnol. 8, 634 (2013). https://doi.org/10.1038/nnano.2013.151

    Article  Google Scholar 

  14. Soklaski, R., Liang, Y., Yang, L.: Temperature effect on optical spectra of monolayer molybdenum disulfide. Appl. Phys. Lett. 104(19), 193110 (2014). https://doi.org/10.1063/1.4878098

    Article  Google Scholar 

  15. Dhall, R., Seyler, K., Li, Z., Wickramaratne, D., Neupane, M.R., Chatzakis, I., Kosmowska, E., Lake, R.K., Xu, X., Cronin, S.B.: Strong circularly polarized photoluminescence from multilayer MoS2 through plasma driven direct-gap transition. ACS Photonics 3(3), 310–314 (2016). https://doi.org/10.1021/acsphotonics.5b00593

    Article  Google Scholar 

  16. Kioseoglou, G., Hanbicki, A.T., Currie, M., Friedman, A.L., Gunlycke, D., Jonker, B.T.: Valley polarization and intervalley scattering in monolayer MoS2. Appl. Phys. Lett. 101(22), 221907 (2012). https://doi.org/10.1063/1.4768299

    Article  Google Scholar 

  17. Mak, K.F., He, K., Shan, J., Heinz, T.F.: Control of valley polarization in monolayer MoS2 by optical helicity. Nat. Nanotechnol. 7, 494 (2012). https://doi.org/10.1038/nnano.2012.96

    Article  Google Scholar 

  18. Mai, C., Barrette, A., Yu, Y., Semenov, Y.G., Kim, K.W., Cao, L., Gundogdu, K.: Many-body effects in valleytronics: direct measurement of valley lifetimes in single-layer MoS2. Nano Lett. 14(1), 202–206 (2014). https://doi.org/10.1021/nl403742j

    Article  Google Scholar 

  19. Jeong, T.Y., Jin, B.M., Rhim, S.H., Debbichi, L., Park, J., Jang, Y.D., Lee, H.R., Chae, D.-H., Lee, D., Kim, Y.-H., Jung, S., Yee, K.J.: Coherent lattice vibrations in mono- and few-layer WSe2. ACS Nano 10(5), 5560–5566 (2016). https://doi.org/10.1021/acsnano.6b02253

    Article  Google Scholar 

  20. Yu, T., Wu, M.W.: Valley depolarization due to intervalley and intravalley electron–hole exchange interactions in monolayer MoS2. Phys. Rev. B 89(20), 205303 (2014)

    Article  Google Scholar 

  21. Zhu, C.R., Zhang, K., Glazov, M., Urbaszek, B., Amand, T., Ji, Z.W., Liu, B.L., Marie, X.: Exciton valley dynamics probed by Kerr rotation in WSe2 monolayers. Phys. Rev. B 90(16), 161302 (2014). https://doi.org/10.1103/PhysRevB.90.161302

    Article  Google Scholar 

  22. del Corro, E., Botello-Méndez, A., Gillet, Y., Elias, A.L., Terrones, H., Feng, S., Fantini, C., Rhodes, D., Pradhan, N., Balicas, L., Gonze, X., Charlier, J.C., Terrones, M., Pimenta, M.A.: Atypical exciton–phonon interactions in WS2 and WSe2 monolayers revealed by resonance Raman spectroscopy. Nano Lett. 16(4), 2363–2368 (2016). https://doi.org/10.1021/acs.nanolett.5b05096

    Article  Google Scholar 

  23. Chernikov, A., Berkelbach, T.C., Hill, H.M., Rigosi, A., Li, Y., Aslan, O.B., Reichman, D.R., Hybertsen, M.S., Heinz, T.F.: Exciton binding energy and nonhydrogenic Rydberg series in monolayer WS2. Phys. Rev. Lett. 113(7), 076802 (2014)

    Article  Google Scholar 

  24. Wang, G., Bouet, L., Lagarde, D., Vidal, M., Balocchi, A., Amand, T., Marie, X., Urbaszek, B.: Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2. Phys. Rev. B 90(7), 075413 (2014)

    Article  Google Scholar 

  25. You, Y., Zhang, X.-X., Berkelbach, T.C., Hybertsen, M.S., Reichman, D.R., Heinz, T.F.: Observation of biexcitons in monolayer WSe2. Nat. Phys. 11, 477 (2015). https://doi.org/10.1038/nphys3324

    Article  Google Scholar 

  26. Hsu, W.-T., Chen, Y.-L., Chen, C.-H., Liu, P.-S., Hou, T.-H., Li, L.-J., Chang, W.-H.: Optically initialized robust valley-polarized holes in monolayer WSe2. Nat. Commun. 6, 8963 (2015). https://doi.org/10.1038/ncomms9963

    Article  Google Scholar 

  27. Sercombe, D., Schwarz, S., Pozo-Zamudio, O.D., Liu, F., Robinson, B.J., Chekhovich, E.A., Tartakovskii, I.I., Kolosov, O., Tartakovskii, A.I.: Optical investigation of the natural electron doping in thin MoS2 films deposited on dielectric substrates. Sci. Rep. 3, 3489 (2013). https://doi.org/10.1038/srep03489

    Article  Google Scholar 

  28. Varshni, Y.P.: Temperature dependence of the energy gap in semiconductors. Physica 34(1), 149–154 (1967). https://doi.org/10.1016/0031-8914(67)90062-6

    Article  Google Scholar 

  29. Arora, A., Koperski, M., Nogajewski, K., Marcus, J., Faugeras, C., Potemski, M.: Excitonic resonances in thin films of WSe2: from monolayer to bulk material. Nanoscale 7(23), 10421–10429 (2015). https://doi.org/10.1039/C5NR01536G

    Article  Google Scholar 

  30. Huang, J., Hoang, T.B., Mikkelsen, M.H.: Probing the origin of excitonic states in monolayer WSe2. Sci. Rep. 6, 22414 (2016). https://doi.org/10.1038/srep22414

    Article  Google Scholar 

  31. Yan, T., Qiao, X., Tan, P., Zhang, X.: Valley depolarization in monolayer WSe2. Sci. Rep. 5, 15625 (2015). https://doi.org/10.1038/srep15625

    Article  Google Scholar 

  32. Lagarde, D., Bouet, L., Marie, X., Zhu, C.R., Liu, B.L., Amand, T., Tan, P.H., Urbaszek, B.: Carrier and polarization dynamics in monolayer MoS2. Phys. Rev. Lett. 112(4), 047401 (2014)

    Article  Google Scholar 

  33. Koirala, S., Mouri, S., Miyauchi, Y., Matsuda, K.: Homogeneous linewidth broadening and exciton dephasing mechanism in MoTe2. Phys. Rev. B 93(7), 075411 (2016)

    Article  Google Scholar 

  34. Dey, P., Paul, J., Wang, Z., Stevens, C.E., Liu, C., Romero, A.H., Shan, J., Hilton, D.J., Karaiskaj, D.: Optical coherence in atomic-monolayer transition-metal dichalcogenides limited by electron–phonon interactions. Phys. Rev. Lett. 116(12), 127402 (2016)

    Article  Google Scholar 

  35. Selig, M., Berghäuser, G., Raja, A., Nagler, P., Schüller, C., Heinz, T.F., Korn, T., Chernikov, A., Malic, E., Knorr, A.: Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides. Nat. Commun. 7, 13279 (2016). https://doi.org/10.1038/ncomms13279

    Article  Google Scholar 

  36. Cadiz, F., Courtade, E., Robert, C., Wang, G., Shen, Y., Cai, H., Taniguchi, T., Watanabe, K., Carrere, H., Lagarde, D., Manca, M., Amand, T., Renucci, P., Tongay, S., Marie, X., Urbaszek, B.: Excitonic Linewidth approaching the homogeneous limit in MoS2-based van der Waals heterostructures. Phys. Rev. X 7(2), 021026 (2017)

    Google Scholar 

  37. Moody, G., Kavir Dass, C., Hao, K., Chen, C.-H., Li, L.-J., Singh, A., Tran, K., Clark, G., Xu, X., Berghäuser, G., Malic, E., Knorr, A., Li, X.: Intrinsic homogeneous linewidth and broadening mechanisms of excitons in monolayer transition metal dichalcogenides. Nat. Commun. 6, 8315 (2015). https://doi.org/10.1038/ncomms9315

    Article  Google Scholar 

  38. Hao, K., Moody, G., Wu, F., Dass, C.K., Xu, L., Chen, C.-H., Sun, L., Li, M.-Y., Li, L.-J., MacDonald, A.H., Li, X.: Direct measurement of exciton valley coherence in monolayer WSe2. Nat. Phys. 12, 677 (2016). https://doi.org/10.1038/nphys3674

    Article  Google Scholar 

  39. Chow, C.M., Yu, H., Jones, A.M., Schaibley, J.R., Koehler, M., Mandrus, D.G., Merlin, R., Yao, W., Xu, X.: Phonon-assisted oscillatory exciton dynamics in monolayer MoSe2. npj 2D Mater. Appl. 1(1), 33 (2017). https://doi.org/10.1038/s41699-017-0035-1

    Article  Google Scholar 

Download references

Acknowledgements

C. Vijila would like to thank Prof. T Venky Venkatesan for access to low temperature Raman and PL spectroscopy facility at NUS. This work was funded by A*STAR Pharos Grant No. 1527000016.

Author information

Authors and Affiliations

  1. Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), #08-03, 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore

    Vijila Chellappan, Ai Lin Christina Pang, Zi En Ooi & Kuan Eng Johnson Goh

  2. NUS Nanoscience and Nanotechnology Initiative (NUSNNI), National University of Singapore, #11- T-Lab, 5A Engineering Drive 1, Singapore, 117411, Singapore

    Soumya Sarkar

  3. NUS Graduate School for Integrative Sciences and Engineering (NGS), #05-01, 28 Medical Drive, Singapore, 117456, Singapore

    Soumya Sarkar

  4. Department of Physics, National University of Singapore, Singapore, 117576, Singapore

    Kuan Eng Johnson Goh

Authors
  1. Vijila Chellappan
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Ai Lin Christina Pang
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Soumya Sarkar
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Zi En Ooi
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Kuan Eng Johnson Goh
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding authors

Correspondence to Vijila Chellappan or Kuan Eng Johnson Goh.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Chellappan, V., Pang, A.L.C., Sarkar, S. et al. Effect of Phonons on Valley Depolarization in Monolayer WSe2. Electron. Mater. Lett. 14, 766–773 (2018). https://doi.org/10.1007/s13391-018-0086-2

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s13391-018-0086-2

Keywords

Search

Navigation