Improved Contacts and Device Performance in MoS₂ Transistors Using a 2D Semiconductor Interlayer

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Schottky barrier height (SBH) and contact resistivity are critical parameters limiting the performance of molybdenum disulfide (MoS2) field-effect transistors (FETs).
• Efficient charge injection and transport in 2D semiconductor devices are essential for advanced electronic applications.

Purpose of the Study:

• To develop a contact engineering strategy to minimize SBH and contact resistivity in MoS2 FETs.
• To investigate the effectiveness of ultrathin 2D semiconductor interlayers for contact modification.

Main Methods:

• Fabrication of MoS2 FETs utilizing ultrathin few-layer MoSe2 as a contact interlayer between the MoS2 channel and Ti electrodes.
• Electrical characterization to measure SBH, contact resistivity, and current transfer length.

Main Results:

• A significant reduction in SBH from ~100 meV to ~25 meV was achieved using MoSe2 interlayers.
• Contact resistivity decreased from ~6 × 10^-5 Ω cm^2 to ~1 × 10^-6 Ω cm^2.
• Current transfer length was reduced from ~425 nm to ~60 nm, indicating improved contact quality.

Conclusions:

• The synergy of Fermi-level pinning in MoSe2 and favorable band alignment with MoS2 effectively lowers the SBH.
• The proposed contact engineering method using MoSe2 interlayers substantially enhances the performance of MoS2 FETs.
• This approach offers a promising route for developing high-performance 2D electronic devices.