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

Sun, Jie, Lin, Na, Tang, Cheng, Ren, Hao, Zhao, Xian
RSC advances 2017 v.7 no.23 pp. 13777-13783
aluminum oxide, chemical degradation, electric field, hydroxylation, phosphorus
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.