Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Hexagonal boron nitride is an indirect bandgap semiconductor

Nature Photonics volume 10, pages 262–266 (2016)Cite this article

Subjects

Abstract

Hexagonal boron nitride is a wide bandgap semiconductor with very high thermal and chemical stability that is used in devices operating under extreme conditions. The growth of high-purity crystals has recently revealed the potential of this material for deep ultraviolet emission, with intense emission around 215 nm. In the last few years, hexagonal boron nitride has been attracting even more attention with the emergence of two-dimensional atomic crystals and van der Waals heterostructures, initiated with the discovery of graphene. Despite this growing interest and a seemingly simple structure, the basic questions of the bandgap nature and value are still controversial. Here, we resolve this long-debated issue by demonstrating evidence for an indirect bandgap at 5.955 eV by means of optical spectroscopy. We demonstrate the existence of phonon-assisted optical transitions and we measure an exciton binding energy of about 130 meV by two-photon spectroscopy.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Monitoring exciton thermalization in phonon replicas.
Figure 2: Phonon-assisted emission and absorption in hBN.
Figure 3: Two-photon excitation spectroscopy in hBN.

Similar content being viewed by others

References

  1. Nanishi, Y. Nobel prize in physics: the birth of the blue LED. Nature Photon. 8, 884–886 (2014).

    Article  ADS  Google Scholar 

  2. Karnik, R. N. Materials science: breakthrough for protons. Nature 516, 173–175 (2014).

    Article  ADS  Google Scholar 

  3. Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 499, 419–425 (2013).

    Article  Google Scholar 

  4. Xu, Y.-N. & Ching, W. Y. Calculation of ground-state and optical properties of boron nitrides in the hexagonal, cubic, and wurtzite structures. Phys. Rev. B 44, 7787–7798 (1991).

    Article  ADS  Google Scholar 

  5. Furthmüller, J., Hafner, J. & Kresse, G. Ab initio calculation of the structural and electronic properties of carbon and boron nitride using ultrasoft pseudopotentials. Phys. Rev. B 50, 15606–15622 (1994).

    Article  ADS  Google Scholar 

  6. Blase, X., Rubio, A., Louie, S. G. & Cohen, M. L. Quasiparticle band structure of bulk hexagonal boron nitride and related systems. Phys. Rev. B 51, 6868–6875 (1995).

    Article  ADS  Google Scholar 

  7. Arnaud, B., Lebègue, S., Rabiller, P. & Alouani, M. Huge excitonic effects in layered hexagonal boron nitride. Phys. Rev. Lett. 96, 026402 (2006).

    Article  ADS  Google Scholar 

  8. Gao, S.-P. Crystal structures and band gap characters of h-BN polytypes predicted by the dispersion corrected DFT and GW method. Solid State Commun. 152, 1817–1820 (2012).

    Article  ADS  Google Scholar 

  9. Watanabe, K., Taniguchi, T. & Kanda, H. Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal. Nature Mater. 3, 404–409 (2004).

    Article  ADS  Google Scholar 

  10. Zunger, A., Katzir, A. & Halperin, A. Optical properties of hexagonal boron nitride. Phys. Rev. B 13, 5560–5573 (1976).

    Article  ADS  Google Scholar 

  11. Evans, D. A. et al. Determination of the optical band-gap energy of cubic and hexagonal boron nitride using luminescence excitation spectroscopy. J. Phys. Condens. Matter 20, 075233 (2008).

    Article  ADS  Google Scholar 

  12. Watanabe, K., Taniguchi, T., Niiyama, T., Miya, K. & Taniguchi, M. Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride. Nature Photon. 3, 591–594 (2009).

    Article  ADS  Google Scholar 

  13. Watanabe, K. & Taniguchi, T. Hexagonal boron nitride as a new ultraviolet luminescent material and its application. Int. J. Appl. Ceram. Technol. 8, 977–989 (2011).

    Article  Google Scholar 

  14. Jaffrennou, P. et al. Origin of the excitonic recombinations in hexagonal boron nitride by spatially resolved cathodoluminescence spectroscopy. J. Appl. Phys. 102, 116102 (2007).

    Article  ADS  Google Scholar 

  15. Watanabe, K. et al. Hexagonal boron nitride as a new ultraviolet luminescent material and its application—fluorescence properties of hBN single-crystal powder. Diam. Relat. Mater. 20, 849–852 (2011).

    Article  ADS  Google Scholar 

  16. Pierret, A. et al. Excitonic recombinations in h-BN: from bulk to exfoliated layers. Phys. Rev. B 89, 035414 (2014).

    Article  ADS  Google Scholar 

  17. Bourrellier, R. et al. Nanometric resolved luminescence in h-BN flakes: excitons and stacking order. ACS Photon. 1, 857–862 (2014).

    Article  Google Scholar 

  18. Silly, M. G. et al. Luminescence properties of hexagonal boron nitride: cathodoluminescence and photoluminescence spectroscopy measurements. Phys. Rev. B 75, 085205 (2007).

    Article  ADS  Google Scholar 

  19. Museur, L. & Kanaev, A. Near band-gap photoluminescence properties of hexagonal boron nitride. J. Appl. Phys. 103, 103520 (2008).

    Article  ADS  Google Scholar 

  20. Museur, L., Feldbach, E. & Kanaev, A. Defect-related photoluminescence of hexagonal boron nitride. Phys. Rev. B 78, 155204 (2008).

    Article  ADS  Google Scholar 

  21. Watanabe, K. & Taniguchi, T. Jahn–Teller effect on exciton states in hexagonal boron nitride single crystal. Phys. Rev. B 79, 193104 (2009).

    Article  ADS  Google Scholar 

  22. Bassani, F. & Pastori Parravicini, G. Electronic States and Optical Transitions in Solids (Pergamon, 1975).

    Google Scholar 

  23. Martienssen, W. & Warlimont, H. (eds) Springer Handbook of Condensed Matter and Materials Data (Springer, 2005).

    Book  Google Scholar 

  24. Cho, K. et al. Excitons (Springer, 1979).

    Book  Google Scholar 

  25. Weisbuch, C. & Ulbrich, R. G. Spatial and spectral features of polariton fluorescence. J. Lumin. 18/19, 27–31 (1979).

    Article  Google Scholar 

  26. Snoke, D. W., Braun, D. & Cardona, M. Carrier thermalization in Cu2O: phonon emission by excitons. Phys. Rev. B 44, 2991 (1991).

    Article  ADS  Google Scholar 

  27. Umlauff, M. et al. Direct observation of free-exciton thermalization in quantum-well structures. Phys. Rev. B 57, 1390 (1998).

    Article  ADS  Google Scholar 

  28. Xu, S. J., Li, G. Q., Xiong, S. J. & Che, C. M. Temperature dependence of the LO phonon sidebands in the free exciton emission in GaN. J. Appl. Phys. 99, 073508 (2006).

    Article  ADS  Google Scholar 

  29. Griffin, A., Snoke, D. W. & Stringari, S. (eds) Bose–Einstein Condensation (Cambridge Univ. Press, 1995).

    Book  Google Scholar 

  30. Serrano, J. et al. Vibrational properties of hexagonal boron nitride: inelastic X-ray scattering and ab initio calculations. Phys. Rev. Lett. 98, 095503 (2007).

    Article  ADS  Google Scholar 

  31. Shtrichman, I. et al. Temporal evolution of the excitonic distribution function in GaAs/AlGaAs superlattices. Phys. Rev. B 65, 153302 (2002).

    Article  ADS  Google Scholar 

  32. Museur, L. et al. Exciton optical transitions in a hexagonal boron nitride single crystal. Phys. Status Solidi 5, 214–216 (2011).

    Google Scholar 

  33. Jaffrennou, P. et al. Near-band-edge recombinations in multiwalled boron nitride nanotubes: cathodoluminescence and photoluminescence spectroscopy measurements. Phys. Rev. B 77, 235422 (2008).

    Article  ADS  Google Scholar 

  34. Reich, S. et al. Resonant Raman scattering in cubic and hexagonal boron nitride. Phys. Rev. B 71, 205201 (2005).

    Article  ADS  Google Scholar 

  35. Lui, C. H. & Heinz, T. F. Measurement of layer breathing mode vibrations in few-layer graphene. Phys. Rev. B 87, 121404 (2013).

    Article  ADS  Google Scholar 

  36. Tarrio, C. & Schnatterly, S. Interband transitions, plasmons, and dispersion in hexagonal boron nitride. Phys. Rev. B 40, 7852–7859 (1989).

    Article  ADS  Google Scholar 

  37. Arenal, R. et al. Electron energy loss spectroscopy measurement of the optical gaps on individual boron nitride single-walled and multiwalled nanotubes. Phys. Rev. Lett. 95, 127601 (2005).

    Article  ADS  Google Scholar 

  38. Wang, F., Dukovic, G., Brus, L. E. & Heinz, T. F. The optical resonances in carbon nanotubes arise from excitons. Science 308, 838–841 (2005).

    Article  ADS  Google Scholar 

  39. Maultzsch, J. et al. Exciton binding energies in carbon nanotubes from two-photon photoluminescence. Phys. Rev. B 72, 241402 (2005).

    Article  ADS  Google Scholar 

  40. Ye, Z. et al. Probing excitonic dark states in single-layer tungsten disulphide. Nature 513, 214–218 (2014).

    Article  ADS  Google Scholar 

  41. Wang, G. et al. Giant enhancement of the optical second-harmonic emission of WSe2 monolayers by laser excitation at exciton resonances. Phys. Rev. Lett. 114, 097403 (2015).

    Article  ADS  Google Scholar 

  42. Tuncel, E. et al. Free-electron laser studies of direct and indirect two-photon absorption in germanium. Phys. Rev. Lett. 70, 4146–4149 (1993).

    Article  ADS  Google Scholar 

  43. Baldereschi, A. & Diaz, M. G. Anisotropy of excitons in semiconductors. Nuovo Cimento B 68, 217–229 (1970).

    Article  ADS  Google Scholar 

  44. Gil, B., Felbacq, D., Guizal, B. & Bouchitté, G. Excitonic states and their wave functions in anisotropic materials: a computation using the finite-element method and its application to AlN. Phys. Status Solidi B 249, 455–458 (2012).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

The authors thank C. L'Henoret, D. Rosales and M. Moret for technical support, L. Tizei, O. Stephan, A. Zobelli, M. Kociak, L. Schue, J. Barjon, A. Loiseau and F. Ducastelle for discussions. This work was financially supported by the network GaNeX (ANR-11-LABX-0014). GaNeX belongs to the publicly funded Investissements d'Avenir programme managed by the French ANR agency. G.C. is a member of the ‘Institut Universitaire de France’.

Author information

Authors and Affiliations

  1. Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, Montpellier, F-34095, France

    G. Cassabois, P. Valvin & B. Gil

Authors
  1. G. Cassabois
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. P. Valvin
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. B. Gil
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

All authors conceived and designed the experiments, which were carried out by G.C. and P.V. The data were analysed by all authors. The interpretation and writing of the manuscript were performed by G.C. and B.G.

Corresponding author

Correspondence to B. Gil.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 1208 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Cassabois, G., Valvin, P. & Gil, B. Hexagonal boron nitride is an indirect bandgap semiconductor. Nature Photon 10, 262–266 (2016). https://doi.org/10.1038/nphoton.2015.277

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nphoton.2015.277

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing