Interface Kinetics Assisted Barrier Removal in Large Area 2D-WS₂ Growth to Facilitate Mass Scale Device Production

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Monolayer tungsten disulfide (WS₂) growth beyond micron scale is challenging.
• Traditional exfoliation methods lack dimensional control.
• Large-area WS₂ is crucial for advanced electronic and optoelectronic devices.

Purpose of the Study:

• To develop a scalable synthesis method for large-area monolayer WS₂ films.
• To investigate the role of reduced graphene oxide (RGO) in promoting WS₂ domain expansion.
• To explore the potential of synthesized WS₂ films in photodetector applications.

Main Methods:

• Chemical vapor deposition (CVD) synthesis of WS₂ on graphene oxide (GO) coated Si/SiO₂ substrates.
• Transformation of GO to reduced graphene oxide (RGO) to facilitate grain boundary joining.
• Characterization using Raman mapping, photoluminescence, Atomic Force Microscopy (AFM), and High-Resolution Transmission Electron Microscopy (HRTEM).
• Fabrication and testing of WS₂-based photodetectors.

Main Results:

• Achieved centimeter-squared size monolayer to few-layer WS₂ films.
• WS₂ domain size expansion was facilitated by sp²-bonded carbon nanostructures in RGO and RGO surface roughness.
• Uniform mono-to-few layer WS₂ growth confirmed across the entire substrate.
• Demonstrated WS₂ photodetectors with highly repetitive cycling response and negligible drift.

Conclusions:

• CVD synthesis on RGO provides a scalable route for large-area WS₂ film production.
• RGO's unique properties, including carbon nanostructures and surface roughness, are key to domain expansion.
• The developed WS₂ films show promise for practical device applications, particularly in photodetectors.