Surface functional group modification induced partial Fermi level pinning and ohmic contact at borophene-MoS₂...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Schottky barriers at electric contacts impede 2D semiconductor device performance.
• Achieving ohmic contact is crucial for enhancing device efficiency.
• Borophene as an electrode material for MoS2 field-effect transistors (FETs) theoretically showed promise but still suffered from Schottky barriers.

Purpose of the Study:

• To investigate surface functional group modification of borophene as a method to regulate Schottky barriers.
• To explore the possibility of achieving ohmic contact between borophene and MoS2.
• To understand the underlying mechanisms of Fermi level pinning (FLP) in van der Waals (vdW) contacts.

Main Methods:

• Utilizing ab initio electronic structure calculations.
• Performing quantum transport simulations.
• Analyzing the impact of surface functional groups on borophene's work function and interface properties.

Main Results:

• Surface functional group modification allows for tunable metal work functions over a wide range.
• Ohmic contact formation with MoS2 was successfully realized.
• Fermi level pinning (FLP) effect was observed in vdW contacts, with interface dipoles and metal-induced gap states (MIGS) identified as key contributors.
• The extent of MIGS was found to depend on the orientation of functional groups relative to the metal-MoS2 interface.

Conclusions:

• Surface functional group modification is an effective strategy for creating ohmic contacts with 2D materials like MoS2.
• The study provides fundamental insights into FLP mechanisms in vdW metal-semiconductor contacts.
• This approach has implications for designing high-performance 2D electronic devices.