- Direct band-gap crossover in epitaxial monolayer boron nitride doi link

Auteur(s): Elias C., Valvin P., Pelini T., Summerfeld Alex, Mellor Chris, Cheng T.s., Eaves L., Foxon C.t., Beton Peter, Novikov Sergei, Gil B., Cassabois G.(Corresp.)

(Article) Publié: Nature Communications, vol. 1 p.1 (2019)
Texte intégral en Openaccess : openaccess

Ref HAL: hal-02156532_v1
DOI: 10.1038/s41467-019-10610-5
WoS: 000471586700016
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Hexagonal boron nitride is a large band-gap insulating material which complements the electronic and optical properties of graphene and the transition metal dichalcogenides. However, the intrinsic optical properties of monolayer boron nitride remain largely unex- plored. In particular, the theoretically expected crossover to a direct-gap in the limit of the single monolayer is presently not confirmed experimentally. Here, in contrast to the tech- nique of exfoliating few-layer 2D hexagonal boron nitride, we exploit the scalable approach of high-temperature molecular beam epitaxy to grow high-quality monolayer boron nitride on graphite substrates. We combine deep-ultraviolet photoluminescence and reflectance spectroscopy with atomic force microscopy to reveal the presence of a direct gap of energy 6.1eV in the single atomic layers, thus confirming a crossover to direct gap in the monolayer limit.