Argon Plasma Induced Phase Transition in Monolayer MoS₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Monolayer molybdenum disulfide (MoS₂) is a promising two-dimensional material with unique electronic properties.
• Controlling the phase of MoS₂ is crucial for tailoring its properties for advanced electronic applications.
• Existing phase engineering techniques can be complex and difficult to scale.

Purpose of the Study:

• To develop a facile, clean, controllable, and scalable method for phase engineering monolayer MoS₂.
• To investigate the localized 2H→1T phase transition induced by Ar-plasma bombardment.
• To fabricate and characterize MoS₂ field-effect transistors (FETs) with engineered phase domains.

Main Methods:

• Utilized weak Ar-plasma bombardment to induce localized 2H→1T phase transitions in monolayer MoS₂.
• Employed scanning tunneling microscopy (STM) to characterize the resulting mosaic structures and identify point defects (S-vacancies).
• Implemented a selected-area phase patterning process to fabricate MoS₂ FETs with controlled 1T phase domains at contact areas.

Main Results:

• Demonstrated that Ar-plasma bombardment can controllably induce 2H→1T phase transitions, forming nanometer-sized 1T domains.
• Confirmed that single sulfur vacancies stabilize these phase transitions.
• Fabricated MoS₂ FETs exhibiting significantly improved performance due to the 1T phase transition in the metal contact regions.

Conclusions:

• The Ar-plasma bombardment technique offers a novel and effective route for phase engineering in monolayer MoS₂.
• This method allows for precise control over phase transitions, leading to enhanced device characteristics.
• The findings open new avenues for phase engineering in other transition metal dichalcogenide (TMD) materials.