Performance improvement in p-Type WS₂field-effect transistors with 1T phase contacts

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Non-ideal metal contacts in 2D material field-effect transistors (FETs) create Schottky barriers, hindering carrier injection and degrading device performance.
• Fermi level pinning further complicates charge transport at the metal-semiconductor interface, limiting the potential of 2D materials.

Purpose of the Study:

• To engineer the metal-semiconductor contact in 2D WS2 FETs by creating a metallic 1T phase at the source/drain regions.
• To investigate the impact of this engineered contact on device performance metrics like carrier mobility and subthreshold slope.

Main Methods:

• Fabrication of 2D WS2 FET devices using lithium (Li) intercalation to induce a metallic 1T phase at the source/drain electrodes.
• Characterization of the engineered 2H-WS2/1T-WS2 junction and comparison of device performance against conventional 2H-WS2 FETs.

Main Results:

• The engineered FET with a 2H-WS2/1T-WS2 junction showed over a 10-fold increase in carrier mobility compared to conventional devices.
• A steeper subthreshold slope was observed, indicating improved gate control and reduced leakage currents.
• Demonstrated boosted carrier injection and reduced tunnel barrier width at the engineered metal contact.

Conclusions:

• Engineering the metal contact with a metallic 1T phase in WS2 FETs effectively overcomes Schottky barrier limitations.
• This approach leads to significantly enhanced device performance, paving the way for high-performance and reproducible 2D nanoelectronics.
• The Li intercalation method offers a viable strategy for fabricating advanced 2D electronic devices.