Direction and strain controlled anisotropic transport behaviors of 2D GeSe-phosphorene vdW heterojunctions

Vertical van der Waals (vdW) heterostructures made up of two or more 2D monolayer materials provide new opportunities for 2D devices. Herein, we study the electronic transport properties of vertical integration of 2D GeSe-phosphorene(GeSe–BP) heterostructure, using the nonequilibrium Green's function formalism combined with the density-functional theory. The results reveal that the directional dependency and strain tunable transport anisotropic behavior appears in GeSe/BP-stacking vdW heterostructures. The current–voltage (I–V) characteristics indicate that the electric current propagates more easily through the perpendicular buckled direction (Y) than the linear atomic chain direction (X) in the low bias regime regardless of the GeSe–BP stacking, which is supported by the underlying electronic structures along Γ–Y and Γ–X lines. The anisotropic transmission spectra indicate an over 10⁵ on/off ratio between the I _Y and I _X in GeSe–BP systems. This anisotropic transmission behavior of 2D GeSe–BP heterojunction is regardless of the considered layer distances. The similar situation can also be found in the I–V characteristics of GeSe–BP nano-device after applying a strain, and a charming behavior that the transport gap can be minished obviously when applied a compressed strain on the perpendicular y-direction or the stretched strain on the x-direction. Moreover, an intriguing semiconductor-metal transition induces by applying the in-plain strain along the y-direction. These results imply that the GeSe–BP nanojunctions may be a promising application in futuristic nano-switching materials. (paper)