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Hexagonal boron nitride is an indirect bandgap semiconductor

Nature Photonics volume 10, pages 262266 (2016) | Download Citation

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.

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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’.

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

    • G. Cassabois
    • , P. Valvin
    •  & B. Gil

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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.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to B. Gil.

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DOI

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

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