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

Abstract

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 MoSi 2 N 4 /M 3 C 2 (M = Zn, Cd, Hg) van der Waals heterostructures (vdWHs). We find that the MoSi 2 N 4 /M 3 C 2 vdWHs can form a p-type ShC with small SBH with the calculated pinning factor S ≈ 0.8 for MoSi 2 N 4 /M 3 C 2 contacts. These results indicate that the FLP effect can be effectively suppressed in MoSi 2 N 4 contact with M 3 C 2 . Moreover, the interfacial properties and SBH of MoSi 2 N 4 /Zn 3 C 2 vdWHs can be effectively modulated by a perpendicular electric field and biaxial strain. In particular, an efficient OhC can be achieved in MoSi 2 N 4 /Zn 3 C 2 vdWHs by applying a positive electric field of 0.5 V/Å and strain of ±8%.

Resistor-to-Schottky barrier analytical model for ohmic contact test structures

“…While 2D materials can exhibit high electron mobility and thermal conductivities, they present challenges. These include the formation of high potential barriers at M-S contacts, complex interfacial properties, and Fermi pinning effects [13,14].…”