Point defects in wurtzite boron nitride

The wurtzite polymorph of boron nitride (wBN) is a superhard, wide band gap semiconductor which can be obtained by inducing a phase transition on the hexagonal phase under high pressure. Samples of wBN were mostly obtained with a shock compression procedure resulting in micrometre-size powder of admixtures of wBN and other boron nitride polymorphs. Although wBN was not thought to be stable at ambient pressure, recently stable millimetre-size wBN samples have been produced [1] and it has been shown that once the wurtzite phase has been obtained it is retained [2].
The stability and hardness of wBN motivates a study of its electronic and optical properties in the pristine phase as an implementation in optoelectronic devices under harsh conditions can be envisaged. Moreover its large band gap makes this material interesting from a defect physics perspective as it may accomodate defect-induced levels. In our work [3] we used Many-Body perturbation theory in the GW approximation on top of Density functional theory simulations to obtain the electronic properties of wBN as a function of pressure. Screening has been included in solving the Bethe-Salpeter equation to compute the optics. Finally, we use the formation energy formalism [4] in the supercell approach to explore the potential of wBN as a host for simple point defects (vacancies and carbon-related substitutionals).

[1] Chunlin Chen, Deqiang Yin, Takeharu Kato, Takashi Taniguchi, Kenji Watanabe, Xiuliang Ma, Hengqiang Ye, and Yuichi Ikuhara, PNAS 116 (23) 11181-11186, https://doi.org/10.1073/pnas.1902820116
[2]A. Segura et al. , R. Cuscó, T. Taniguchi, K. Watanabe, G. Cassabois, B. Gil, and L. Artús, The Journal of Physical Chemistry C 2019 123 (33), 20167-20173, DOI: 10.1021/acs.jpcc.9b06163
[3]Martino Silvetti, Claudio Attaccalite and Elena Cannuccia, Pressure dependence of electronic, vibrational and optical properties of wurtzite-boron nitride, Phys. Rev. Materials 7, 055201 (2023), https://doi.org/10.1103/PhysRevMaterials.7.055201
[4]Christoph Freysoldt, Blazej Grabowski, Tilmann Hickel, Jörg Neugebauer, Georg Kresse, Anderson Janotti, and Chris G. Van de Walle, Rev. Mod. Phys. 86, 253 – Published 28 March 2014

The speaker acknowledges support from:
ANR (Agence Nationale de la Recherche)
Mésocentre d'Aix-Marseille Université
TGCC (Très grand centre de calcul du CEA)