In this computational work based on density functional theory, we study the electronic and electron transport properties of asymmetric multilayer MoSSe junctions, known as Janus junctions. Focusing on four-layer systems, we investigate the influence of electric field, electrostatic doping, strain, and interlayer stacking on the electronic structure. We discover that a metal-to-semiconductor transition can be induced by an out-of-plane electric field. The critical electric field for such a transition can be reduced by in-plane biaxial compressive strain. Due to an intrinsic electric field, a four-layer MoSSe can rectify out-of-plane electric current. The rectifying ratio reaches 34.1 in a model junction Zr/four-layer MoSSe/Zr and can be further enhanced by increasing the number of MoSSe layers. In addition, we show a drastic sudden vertical compression of four-layer MoSSe due to in-plane biaxial tensile strain, indicating a second phase transition. Furthermore, an odd-even effect on electron transmission at the Fermi energy for Zr/$n$-layer MoSSe/Zr junctions with $n=1,2,3,\cdots ,10$ is observed. These findings reveal the richness of physics in this asymmetric system, and they strongly suggest that the properties of four-layer MoSSe are highly tunable, thus providing a guide to future experiments relating to materials research and nanoelectronics.

• Received 24 November 2020
• Revised 2 June 2021
• Accepted 9 June 2021

DOI:https://doi.org/10.1103/PhysRevMaterials.5.064007

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Published by the American Physical Society