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

Abstract

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.