Mechanism of Dipole Moment Effect on the Schottky Barrier at Janus MoSH/MoSiGeN4 Metal-Semiconductor Interfaces.

Controlling the Schottky barrier (SB) at metal-semiconductor interfaces is crucial for achieving efficient carrier injection in two-dimensional electronic devices. The dipole moment crucially governs the Schottky barrier height (SBH) in Janus van der Waals heterostructures (vdWHs). However, the physical mechanism of dipole moment-controlled SB remains unclear. Furthermore, how external tuning manipulates dipoles to achieve SBH control remains a challenge. Here, based on the first-principle calculations, we have investigated the interfacial electronic properties, dipole moment, and modulation of SB and tunneling properties for Janus MoSH/MoSiGeN4 vdWH. We identify the potential step ΔV as the decisive quantity governing the SBH, which can be continuously tuned between 0.41 eV and 0.98 eV, resulting in p-type or n-type Schottky contacts (ShC). This ΔV originates from the synergistic interplay between the intrinsic and interface dipole moments, establishing a clear physical mechanism for the observed SBH variation. Furthermore, external electric fields and interlayer distance can effectively modulate the SBH by altering the total dipole moment and the resulting ΔV. Finally, compared to electric fields, reducing the interlayer distance more significantly enhances the tunneling probability and lowers the tunneling-specific resistivity. Our findings reveal the fundamental physics governing contact behavior in this Janus-based heterostructure and provide practical design guidelines.