Chen Tong, Xu Liang, Li Quan, Li Xiaobo, Long Mengqiu
School of Energy and Mechanical Engineering, Jiangxi University of Science and Technology, Nanchang 330013, People's Republic of China. Energy materials computing center, Jiangxi University of Science and Technology, Nanchang 330013, People's Republic of China. Center for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada.
Nanotechnology. 2019 Nov 1;30(44):445703. doi: 10.1088/1361-6528/ab375b.
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 10 on/off ratio between the I and I 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.
由两种或更多二维单层材料组成的垂直范德华（vdW）异质结构为二维器件提供了新的机遇。在此，我们使用非平衡格林函数形式结合密度泛函理论，研究了二维GeSe-磷烯（GeSe-BP）异质结构垂直集成的电子输运性质。结果表明，在GeSe/BP堆叠的vdW异质结构中出现了方向依赖性和应变可调的输运各向异性行为。电流-电压（I-V）特性表明，在低偏置状态下，无论GeSe-BP的堆叠情况如何，电流在垂直弯曲方向（Y）上比在直线原子链方向（X）上更容易传播，这由沿Γ-Y和Γ-X线的底层电子结构所支持。各向异性传输光谱表明，在GeSe-BP系统中，I和I之间的开/关比超过10。二维GeSe-BP异质结的这种各向异性传输行为与所考虑的层间距无关。在施加应变后的GeSe-BP纳米器件的I-V特性中也能发现类似情况，并且当在垂直y方向施加压缩应变或在x方向施加拉伸应变时，会出现一种迷人的行为，即输运能隙可以明显减小。此外，沿y方向施加面内应变会引发有趣的半导体-金属转变。这些结果表明，GeSe-BP纳米结在未来的纳米开关材料中可能具有广阔的应用前景。
