Semiconductor-metal transition induced by combined electric field and external strain in bilayer phosphorene.

The gap modulation by effectively external control is an intriguing feature of the black phosphorene which may enable a flexible design and optimization of electronics. In this paper, combined electric field and external strain effects are systematically investigated to tailor the electrical properties of bilayer black phosphorene (BP) in four stacking order by using density functional theory (DFT). The electronic structures and density of states of bilayer black phosphorene can be modulated by the two external controls, the direct semiconductor-indirect semiconductor-metal transitions emerge under uniaxial in-plain strains and vertical electric field. The band gap is more likely to be modulated by the electric field under compressive strain along armchair direction for the AB stacking structures. The greater the compressive strain, the gap closed at a lower electric field. The partial density of states (PDOS) shows the energy band was mainly contributed by p orbital, and the partial charge density of the VBM and CBM further indicates the shifting trend of electrons and holes between the double layers. Our results provide potential reference information for nano-electronic and optoelectronic applications. • We consider the combination effect of in-plain external force and vertical electric field in bilayer phosphorene. We adopt PBE-TS-DFTD method for structure optimization. • Four stacking orders are considered comprehensively, both the armchair and zigzag direction of the applied in-plain strain are considered. • We report a different modulation effects between compressive force and tensile force under electric field. The direct semiconductors to indirect semiconductors turning points are discussed. • Detailed partial charge density of the VBM and CBM explains the mechanism. [ABSTRACT FROM AUTHOR]