Deterministic grayscale nanotopography to engineer mobilities in strained MoS₂ FETs.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional materials (2DMs) offer potential for next-generation electronics due to their atomically thin channels.
• Low carrier mobility in 2DM transistors, primarily due to electron-phonon scattering, hinders their performance.
• Overcoming scattering limitations is crucial for realizing the full potential of 2DM-based electronics.

Purpose of the Study:

• To investigate the controlled introduction of localized tensile strain as a method to enhance carrier mobility in 2DM transistors.
• To mitigate electron-phonon scattering by applying strain to the 2DM channel.
• To demonstrate a novel nanofabrication approach for strain engineering in 2DMs.

Main Methods:

• Conformal adhesion of 2DMs onto a nanoengineered dielectric layer using van der Waals forces.
• Utilizing a gray-tone topography on the dielectric surface to induce localized tensile strain.
• Fabrication and characterization of monolayer MoS2 field-effect transistors (FETs) under controlled strain conditions.

Main Results:

• Monolayer MoS2 FETs exhibited an 8-fold increase in on-state current when subjected to tensile strain.
• Achieved carrier mobilities of 185 cm²/Vs at room temperature, significantly improved by strain engineering.
• Experimental results showed good agreement with theoretical calculations for strain-induced mobility enhancement.

Conclusions:

• Controlled tensile strain is an effective strategy to suppress electron-phonon scattering and enhance carrier mobility in 2DM transistors.
• Nanotopographic grayscale surface engineering provides a viable route for fabricating strained 2DM devices.
• This approach holds promise for the development of high-performance photonic and nanoelectronic devices.