NaCl-Assisted One-Step CVD for In-Plane 1T/1H Heterophase Homojunctions in Monolayer WS₂.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional tungsten disulfide (WS₂) exhibits distinct semiconducting (1H) and metallic (1T) phases.
• Challenges exist in stabilizing the 1T phase and achieving controlled phase coexistence in WS₂.

Purpose of the Study:

• To develop a scalable method for the spatial coexistence and precise control of 1H and 1T phases in monolayer WS₂.
• To investigate the relationship between precursor ratios and WS₂ structural phases.
• To understand the electronic properties at the heterophase interface.

Main Methods:

• NaCl-assisted one-step chemical vapor deposition for WS₂ synthesis.
• Phase diagram construction based on precursor ratios.
• Density functional theory (DFT) calculations for electronic structure analysis.
• Kelvin probe force microscopy (KPFM) for work function measurements.

Main Results:

• Achieved spatial coexistence and precise control of 1H and 1T phases in monolayer WS₂.
• Established a clear correlation between precursor ratios and WS₂ phases via a phase diagram.
• DFT calculations elucidated the electronic stability differences between 1H and 1T phases.
• Experimental work functions from KPFM validated the calculated electronic properties.

Conclusions:

• The NaCl-assisted CVD method offers a scalable and efficient route for WS₂ phase engineering.
• Controlled heterophase interfaces in WS₂ hold significant potential for optoelectronics and catalysis.