Mobility Enhancement of Strained MoS₂ Transistor on Flat Substrate

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Strain engineering is a key strategy for enhancing carrier mobility in two-dimensional (2D) semiconductors.
• Current methods often involve flexible or nanostructured substrates, introducing confounding factors like dielectric variations and interface scattering.
• The precise impact of pure lattice strain on 2D semiconductor performance remains an open question.

Purpose of the Study:

• To develop a novel strain engineering technique for fabricating highly strained 2D semiconductor transistors on flat substrates.
• To investigate the effect of pure lattice strain on the carrier mobility of Molybdenum Disulfide (MoS2) transistors.
• To provide a reliable method for achieving high-performance 2D transistors through controlled strain application.

Main Methods:

• A mechanical lamination technique was employed to transfer prefabricated MoS2 transistors onto a custom-designed trench structure on a flat substrate.
• This method allows for uniform strain generation across the 2D channel while maintaining a flat substrate and dielectric interface.
• The strain was applied using controlled tension and compression.

Main Results:

• Electron mobility in MoS2 transistors was demonstrably enhanced by tensile strain and reduced by compressive strain, aligning with theoretical predictions.
• A maximum mobility enhancement of 152% was observed for monolayer MoS2 and 64% for bilayer MoS2 transistors.
• The strain engineering method ensured no roughness-induced scattering or dielectric environment changes.

Conclusions:

• The developed technique enables uniform strain application to layered semiconductors on flat, solid substrates.
• This method effectively boosts the carrier mobilities of 2D transistors, offering a pathway to high-performance devices.
• The findings confirm the significant role of pure lattice strain in modulating the electronic properties of 2D materials.