Solution-Based Synthesis of Few-Layer WS₂ Large Area Continuous Films for Electronic Applications

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Solution-based synthesis of molybdenum disulfide (MoS₂) ultra-thin films for electronics is well-established.
• Growing uniform, large-area few-layer tungsten disulfide (WS₂) films via solution methods remains a significant challenge.

Purpose of the Study:

• To develop a facile, scalable method for producing continuous and uniform few-layer WS₂ films over centimeter scales.
• To demonstrate the electronic functionality of WS₂ films synthesized using the novel precursor method.

Main Methods:

• Spin coating ammonium tetrathiotungstate ((NH₄)₂WS₄) onto substrates.
• Two-step high-temperature annealing of the precursor films without additional sulfurization.
• Characterization using Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Raman Spectroscopy, and X-Ray Photoelectron Spectroscopy (XPS).

Main Results:

• Achieved continuous and uniform few-layer WS₂ films over centimeter-scale areas.
• Confirmed the few-layer nature, high crystallinity, and stoichiometric composition of the synthesized WS₂ films.
• Successfully fabricated a backgated Field Effect Transistor (FET) device using as-deposited WS₂ films.

Conclusions:

• The developed thermolysis method offers a scalable and facile route for WS₂ film growth, overcoming previous uniformity limitations.
• The synthesized WS₂ films exhibit excellent material properties suitable for electronic device applications.
• This work validates the precursor-based synthesis approach for fabricating functional WS₂-based electronic devices.