Extending Schottky-Mott rule to van der Waals heterostructures of 2D Janus materials: Influence of intrinsic dipoles

The Schottky-Mott (S-M) limit based on the S-M rule is often used to evaluate the Schottky barrier height (SBH) at metal-semiconductor (MS) van der Waals (vdW) contacts but fails at the polar interfaces. In order to extend the S-M rule to the polar interfaces, we here modify the S-M equation to predict the SBH at vdW interfaces of 2D Janus materials, taking into account the effects of intrinsic and interface dipoles. The modified S-M equation is verified based on the first-principles calculations of the MoSi2As2P2/HTaSe2F vdW interfaces, showing a sharp dependence of SBH on the dipole amplitude and direction. Specifically, n-type Schottky barriers tend to form when a semiconductor contacts with a low-work-function surface of Janus metal or a metal interfaces to the high-electron-affinity surface of Janus semiconductor; otherwise, a p-type one is preferable. Interestingly, the smallest n(p)-type SBH could be attained when both intrinsic dipole directions are the same. This work demonstrates that the S-M rule can be extended to the polar interfaces and dipole engineering is an effective strategy to tune the SBH at the MS interface.

Automated summary

This study modifies the S-M equation to predict the Schottky barrier height at van der Waals interfaces of 2D Janus materials, taking into account the effects of intrinsic and interface dipoles. It demonstrates that the S-M rule can be extended to polar interfaces and dipole engineering is an effective strategy to tune the Schottky barrier height at the metal-semiconductor interface.