Two new BN polymorphs with wide-bandgap

Abstract

Two boron nitride polymorphs, denoted as P-62m BN and I-43d BN, are investigated in this work: P-62m BN with sp2 + sp3 hybridizations, and I-43d BN with sp3 hybridization. P-62m BN and I-43d BN are mechanically, thermally, and dynamically stable. As predicted by the electronic band structure, both P-62m BN and I-43d BN are wide band gap semiconductor materials, and P-62m BN is an ultrawide band gap semiconductor material because the band gap of P-62m BN exceeds that of Ga2O3 and diamond. Meanwhile the band gap of I-43d BN is larger than that of ZnO, GaN and SiC. Both the B/G ratios of P-62m BN and I-43d BN are smaller than 1.75, which confirms that they are brittle materials. The P-62m BN and I-43d BN show different degrees of elastic anisotropy in Young's modulus in this work. In addition, to better distinguish these BN polymorphs in the future, X-ray diffraction patterns of P-62m BN and I-43d BN are also studied.