Modulating the electronic properties and band alignments of the arsenene/MoSi2N4 van der Waals heterostructure via applying strain and electric field.

The two-dimensional (2D) MoSi2N4 monolayer fabricated recently has attracted extensive attention due to its exotic electronic properties and excellent stability for future applications. Using first-principles calculations, we have shown that the electronic properties of the arsenene/MoSi2N4 van der Waals (vdW) heterostructure can be effectively modulated by applying in-plane/vertical strain and vertical electric field. The arsenene/MoSi2N4 vdW heterostructure has type-II band alignment, facilitating the separation of photogenerated electron-hole pairs. The heterostructure is predicted to have an indirect bandgap of about 0.52 eV by using the PBE functional (0.87 eV by using the hybrid functional). Furthermore, under εz = 0.5 Å vertical tensile strain or -0.05 V Å-1 vertical electric field, the arsenene/MoSi2N4 heterostructure can not only experience transition from an indirect to a direct bandgap semiconductor, but also exhibit type-II to type-I band alignment transition. The calculated optical absorption properties reveal that the formation of the vdW heterostructure can effectively enhance the light absorption, and the absorption coefficient in visible and ultraviolet regions is much higher than those of the arsenene and the MoSi2N4 monolayer. Most importantly, based on charge transfer analysis, we proposed the modulation mechanism of the electronic properties of the vdW heterostructure influenced by vertical strain and electric field. Our study provides physical insights into manipulating the electronic and optoelectronic properties of MoSi2N4 based vdW heterostructures, which may be helpful for their practical applications.

First principles study of BAs/MoSi2N4 van der Waals heterostructure: tunable electronic and optical properties via vertical strain.

Constructing van der Waals heterostructures from layered materials can form new optoelectronic devices with superior performance to the individual monolayers. Here, we use first-principles calculations to explore the modulation of a two-dimensional BAs/MoSi2N4 van der Waals heterostructure via strain, including the structure stabilities, electronic properties, charge transfer, and optical properties. Our calculated results reveal that the BAs/MoSi2N4 heterostructure has a direct bandgap of 0.72 eV and type-I band alignment. In addition, the BAs/MoSi2N4 heterostructure exhibits enhanced light absorption in the visible light region. The electronic properties of the BAs/MoSi2N4 heterostructure are tunable by vertical strain, exhibiting a direct to indirect bandgap transition as well as a type-I to type-II band alignment transition when the vertical distance is reduced. Our research provides a comprehensive understanding of the electronic and optical properties of the BAs/MoSi2N4 heterostructure and could be helpful for their potential applications in optoelectronic devices.