A first principles study of the interaction between two-dimensional black phosphorus and Al2O3 dielectric

The chemical degradation of exfoliated black phosphorus (BP) when exposed to ambient conditions can be effectively suppressed via the deposition of Al2O3 dielectric on the BP surface. A good understanding of the interactions between the BP layer and Al2O3 dielectric is important for practical device applications. In the presented paper, first principles calculations have been performed to study the structural, energetic, and electronic properties of BP on an Al-terminated and hydroxylated Al2O3 (0001) surface. Our calculations indicate the band gap of monolayer BP is enlarged by about 160 meV and 92 meV after the deposition respectively of an Al-terminated and hydroxylated Al2O3 surface, which is mainly due to interlayer charge transfer between the BP and Al2O3 surfaces. However, this trend for increasing band gap is inverted upon increasing the number of BP layers. Besides, the valence-band offset of a few-layer (2–4 layer) BP/ Al2O3 system is about 0.5–0.9 eV larger than that of a monolayer BP/Al2O3 system, which is more suitable for creating an injection barrier. Moreover, the band gaps of BP/Al2O3 systems could be tuned using an external electric field for practical applications.