Asymmetric Van der Waals Contact Engineering for Tunable Carrier Transport in MoS Transistors

This work presents the fabrication of transistors with asymmetric metal electrodes (Au-Ag, Pt-Ag, Au-Pt) on MoS channel materials using the semi-dry transfer technique. Raman spectroscopy and atomic force microscopy characterization confirmed that the transfer process did not damage the intrinsic structure of MoS. Electrical tests reveal that by selecting different combinations of work functions for the electrodes, the dominant carrier type (n-type or p-type) of the device could be effectively controlled: Ag electrodes facilitate electron injection, leading to n-type dominant transport; Pt electrodes facilitate hole injection, resulting in ptype dominant transport. Band analysis indicates that the van der Waals (vdW) contact significantly suppressed the interface Fermi level pinning effect, making the metal work function the dominant factor determining the Schottky barrier. This work provides direct experimental evidence and a simple electrode selection strategy for the design of controllable functional devices based on two-dimensional semiconductors.