Ultralow P-Type Contact Resistance Enabled by Evaporated SnS Contacts

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) semiconductors are crucial for next-generation electronics, but scalable p-type contacts remain a significant challenge for complementary metal-oxide semiconductor (CMOS) scaling.
• Existing methods using high-work-function metals often lead to Fermi-level pinning and high contact resistance, hindering device performance.

Purpose of the Study:

• To introduce a novel semiconductor-semiconductor van der Waals (S-S vdW) contact strategy for 2D materials.
• To overcome the limitations of traditional metal contacts for p-type 2D field-effect transistors (p-FETs).

Main Methods:

• Utilized tin sulfide (SnS) as a contact material for WSe2 transistors.
• Investigated the suppression of metal-induced gap states and defect-induced gap states through low-energy deposition of SnS.
• Characterized the electrical properties of SnS-WSe2 transistors.

Main Results:

• SnS contacts demonstrated minimal Fermi-level pinning and a negligible hole-injection barrier, outperforming conventional metal contacts (Pd, Pt).
• Achieved high on-off ratios (>10^10) and low contact resistance (395 Ω μm) in SnS-WSe2 transistors.
• Demonstrated high on-state current density (1.11 mA μm^-1) with a short channel length (60 nm).

Conclusions:

• The SnS S-S vdW contact strategy offers a practical and reliable approach for high-performance 2D p-FETs.
• This work paves the way for scalable integration of 2D materials into advanced CMOS technology.