Electrical Contacts in Monolayer MoSi₂N₄ Transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Monolayer MoSi2N4 is a promising 2D material for next-generation transistors due to its stability, bandgap, and high carrier mobilities.
• Efficient electrical contacts are critical for optimizing carrier injection and device performance in 2D material-based transistors.
• Understanding metal-semiconductor interfaces is crucial for designing high-performance electronic devices.

Purpose of the Study:

• To systematically investigate the electrical contact properties between various metal electrodes and monolayer MoSi2N4.
• To identify optimal metal contacts for achieving efficient carrier injection in MoSi2N4 transistors.
• To explore the factors influencing contact behavior, including Fermi level pinning and band alignment.

Main Methods:

• Utilized density functional theory (DFT) combined with the nonequilibrium Green's function (NEGF) method to simulate quantum transport.
• Analyzed both vertical and horizontal interfaces between typical metal electrodes and monolayer MoSi2N4.
• Calculated tunneling barriers, Schottky barriers, and Fermi pinning factors for different metal-MoSi2N4 combinations.

Main Results:

• Scandium (Sc) and Titanium (Ti) were identified as optimal metals, forming n-type Ohmic contacts with zero tunneling barriers.
• Indium (In) formed n-type contacts with zero Schottky barriers but a significant tunneling barrier (3.11 eV).
• Copper (Cu) and Gold (Au) formed n-type Schottky contacts, while Platinum (Pt) formed a p-type contact.
• High Fermi pinning factors (>0.51) were observed, showing a strong positive correlation with the band gap of MoSi2N4.

Conclusions:

• Sc and Ti are excellent candidates for contact metals in monolayer MoSi2N4 transistors, facilitating efficient electron injection.
• The study provides crucial insights for optimizing electrical contacts in MoSi2N4-based field-effect transistors (FETs).
• Monolayer MoSi2N4 demonstrates significant potential as a channel material for advanced electronic devices.