Efficient Modulation of Schottky to Ohmic Contact in MoSi2N4/M3C2 (M = Zn, Cd, Hg) van der Waals Heterostructures

A strong Fermi level pinning (FLP) effect can induce a large Schottky barrier in metal/semiconductor contacts; reducing the Schottky barrier height (SBH) to form an Ohmic contact (OhC) is a critical problem in designing high-performance electronic devices. Herein, we report the interfacial electronic features and efficient modulation of the Schottky contact (ShC) to OhC for MoSi₂N₄/M₃C₂ (M = Zn, Cd, Hg) van der Waals heterostructures (vdWHs). We find that the MoSi₂N₄/M₃C₂ vdWHs can form a p-type ShC with small SBH with the calculated pinning factor S ≈ 0.8 for MoSi₂N₄/M₃C₂ contacts. These results indicate that the FLP effect can be effectively suppressed in MoSi₂N₄ contact with M₃C₂. Moreover, the interfacial properties and SBH of MoSi₂N₄/Zn₃C₂ vdWHs can be effectively modulated by a perpendicular electric field and biaxial strain. In particular, an efficient OhC can be achieved in MoSi₂N₄/Zn₃C₂ vdWHs by applying a positive electric field of 0.5 V/Å and strain of ±8%.