- The Determination of the Optical Bandgap of the Bernal and Rhombohedral Boron Nitride Polymorphs doi link

Auteur(s): Rousseau A., Moret M., Valvin P., Desrat W., Li Jiahan, Xue Lianjie, Janzen E., Edgar James, Cassabois G., Gil B.(Corresp.)

(Article) Publié: Physical Review Materials, vol. 5 p.064602 (2021)

Ref HAL: hal-03263151_v1
DOI: 10.1103/PhysRevMaterials.5.064602
WoS: 000663317400002
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We report a study of polymorphic boron nitride samples. We interpret the photoluminescence line at 6.032±0.005 eV, that can be recorded at 8K in sp2-bonded boron nitride, as being the signature of the excitonic fundamental bandgap of the Bernal (or graphitic) boron nitride polymorph (bBN). This is determined by advanced photoluminescence measurements combined with x-ray characterizations on pure hexagonal boron nitride (hBN) and on polymorphic crystal samples, later compared with the theoretical predictions of Lorenzo Sponza, et al., Physical Review B 98, 125206 (2018). The overall picture is consistent with a direct excitonic fundamental bandgap of the Bernal (or graphitic) polymorph of boron nitride. This value dXb = 6.032±0.005 eV is higher than the indirect bandgap of hBN (iXh =5.955±0.005 eV).