The optical and tunable electronic properties of BAs/ZnSe heterostructures under the influence of strain and electric field

Abstract

The development of two-dimensional materials is currently rapid due to their outstanding electronic and optical properties, and research on them has never ceased. Our study explored the geometric and electro-optical characteristics of a novel BAs/ZnSe heterostructure through first-principles calculations. We also researched the effects of P atom doping and the stacking of rotated monolayers on the functioning of the BAs/ZnSe heterostructure. Findings from our analysis suggest that the BAs/ZnSe heterostructure embodies a type-II heterojunction, and its band gap is 0.38 eV. This configuration facilitates the efficient division of photoexcited electron–hole pairs at the heterointerface. When the layer spacing reaches 3.3 Å, the binding energy is the lowest and the heterojunction is the most stable. The introduction of an electric field and mechanical stress will lead to the modification of the heterostructure's band gap, ultimately reducing it to zero, thereby exhibiting metallic properties. It is noteworthy that when using an electric field range of −0.9 < E_ext < −0.7 eV Å⁻¹, the BAs/ZnSe heterostructure transfers from a type-II heterojunction to a type-I heterojunction, and becomes a direct band gap. A similar transition also occurs when the applied stress range is 3% < ε < 6%, and there's a type-I to type-II transition. In particular, compared to the individual monolayers, the BAs/ZnSe heterostructure exhibits enhanced optical absorption coefficients, notably in the ultraviolet absorption spectrum, exhibiting an expanded range of absorption. The light absorption capability will also vary with different electric fields and strains. This suggests that the BAs/ZnSe heterostructure can shine in a wider range of applications.