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Van der Waals (vdW) heterostructure, vertically assembled by two kinds of two-dimensional layered materials with extraordinary electronic and optical properties, has emerged as an interesting candidate in the applications of electronics and optoelectronics. It is known that vacancies are crucial in determining the physical properties of materials, and always exist in the materials during the process of actual experimental preparations and can be artificially introduced. In the present work, the structures and electronic properties of a black phosphorus/molybdenum disulfide (BP/MoS2) vdW heterostructure with P atom vacancies are investigated via first principles calculations. Based on the structural symmetry, two types of heterostructures with single-atom vacancy and three types of heterostructures with diatomic vacancies are constructed. It is found that the presence of a single P atom vacancy leads to the transformation from semiconductor to metal in the BP/MoS2 heterostructure, which is mainly due to the contribution of the remaining P atomic p orbitals based on analyses of the partial density of states (PDOS). On the other hand, the heterostructures with diatomic P atom vacancies still maintain their pristine semiconductor features, along with a decrease in their bandgap value. In addition, the plane electrostatic potential indicates that the introduction of P atom vacancy defects causes a change in the electrostatic potential of the BP atomic layer, resulting in asymmetric electrostatic potential on both sides of the BP layer. Finally, it is interesting to note that the accumulation-depletion of electrons occurs around the vacancy, but also partially emerges at the MoS2 layer. Our results provide the possibility for the application of 2D-vacancy-defect heterostructure systems.

Metal atom adsorption is recently considered to be an efficient approach to achieve stability of black phosphorus required by practical devices with no damage to its pristine excellent properties. Using first-principles calculations, we studied the structures and electronic properties of monolayer black phosphorus with Fe atom adsorption under different biaxial strain. Monolayer BP becomes an indirect bandgap semiconductor due to the contribution of adsorbed Fe atom. Strain is considered as a promising way to turn the electronic structures of the adsorption systems. The compressive strain reduces the band gap value of the systems, and eventually results in a semiconductor-metal transition when the strain reaches −8%. The tensile strain would turn the value of band gap ranging from 0.96 eV to 0.60 eV, and an indirect-direct band gap transition would occur with the tensile strain of 4%. In addition, it is found that the charge density difference and charge transfer nearly unchanged under different strain, means that the Fe–P covalent bonds are very strong. The combination of adjustable electronic properties with stability makes black phosphorus an attractive material for fundamental physics studies.

Antimony phosphorus in the alpha phase (α-SbP) is a novel two-dimensional binary material with suitable band gap and environmental stability, it has attracted attention for its promising applications in the field of optoelectronics. In this work, the electronic and optical properties of α-SbP monolayer under biaxial strain have been studied by first principles calculation method based on density functional theory. It is found that when the tensile strain is applied, the band gap value of monolayer SbP increases firstly and then decreases under tensile strain, but the whole band gap value fluctuated is controlled within 0.08 eV. However, in the process of applying compressive strain, the band gap value decreases linearly with the strain value, and semiconductor-metal transition occurs at about −5% strain value. This is due to the difference in coupling between Sb and P atoms. Its optical properties under different strains are analyzed in detail, and it is found that the optical properties of SbP changed little under tensile strain, the light absorption peak is mainly concentrated in the ultraviolet region. In contrast, the compressive strain significantly adjust the optical properties of SbP. The innovation of this work is that the optoelectronic properties of SbP are studied by means of biaxial strain regulation. We find that the optoelectronic properties of SbP are robust to tensile strain. On the other hand, compressive strain has a significant effect on the photoelectric properties of SbP, and semiconductor-metal phase transition occurs. The research work in this paper provides theoretical support for the applications of monolayer α-SbP as a robust tensile and flexible compression material in optoelectronic nanodevices.