The Contact Properties of Monolayer and Multilayer MoS 2 -Metal van der Waals Interfaces.

The contact resistance formed between MoS 2 and metal electrodes plays a key role in MoS 2 -based electronic devices. The Schottky barrier height (SBH) is a crucial parameter for determining the contact resistance. However, the SBH is difficult to modulate because of the strong Fermi-level pinning (FLP) at MoS 2 -metal interfaces. Here, we investigate the FLP effect and the contact types of monolayer and multilayer MoS 2 -metal van der Waals (vdW) interfaces using density functional theory (DFT) calculations based on Perdew-Burke-Ernzerhof (PBE) level. It has been demonstrated that, compared with monolayer MoS 2 -metal close interfaces, the FLP effect can be significantly reduced in monolayer MoS 2 -metal vdW interfaces. Furthermore, as the layer number of MoS 2 increases from 1L to 4L, the FLP effect is first weakened and then increased, which can be attributed to the charge redistribution at the MoS 2 -metal and MoS 2 -MoS 2 interfaces. In addition, the p-type Schottky contact can be achieved in 1L-4L MoS 2 -Pt, 3L MoS 2 -Au, and 2L-3L MoS 2 -Pd vdW interfaces, which is useful for realizing complementary metal oxide semiconductor (CMOS) logic circuits. These findings indicated that the FLP and contact types can be effectively modulated at MoS 2 -metal vdW interfaces by selecting the layer number of MoS 2 .