Scaling two-dimensional semiconductor nanoribbons for high-performance electronics

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Future transistors require 3D architectures (GAA, CFETs) with channel widths in the tens of nanometers.
• Monolayer transition metal dichalcogenides (TMDs) are promising atomically thin channel materials.
• Current TMD field-effect transistors (FETs) are limited to micrometer-scale widths.

Purpose of the Study:

• Investigate the impact of channel width scaling on monolayer TMD nanoribbon transistors.
• Determine if performance can be preserved or enhanced at ultra-scaled widths.
• Explore the underlying mechanisms responsible for performance changes.

Main Methods:

• Fabrication and characterization of monolayer MoS2 nanoribbon FETs with widths down to ~30-40 nm.
• Electrical performance analysis, including on-current density and subthreshold swing.
• Investigation of contact resistance and edge effects.

Main Results:

• Channel width scaling enhanced device performance, increasing median on-current density by ~42% and reducing median subthreshold swing by ~16%.
• Champion MoS2 device achieved 995 µA µm⁻¹ on-current density.
• Contact resistance reduced from ~860 Ω µm to ~270 Ω µm due to minimal edge disorder, enhanced electrostatics, and efficient side-contact injection.
• Achieved 357 µA µm⁻¹ on-currents in WSe2 p-FETs.

Conclusions:

• Ultra-scaled monolayer TMD nanoribbon FETs offer enhanced performance compared to wider counterparts.
• Performance improvements are attributed to reduced edge disorder, better gate electrostatics, and improved contact injection.
• Monolayer TMD nanoribbon FETs are viable candidates for future ultra-scaled electronic devices.