Growth of large sized two-dimensional MoS₂ flakes in aqueous solution

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Layered transition metal dichalcogenides (TMDs), like molybdenum disulfide (MoS2), are promising for next-generation electronics due to their large lateral size and low dimensions.
• Developing scalable, cost-effective growth techniques is essential for integrating TMDs into modern electronic and optoelectronic devices.

Purpose of the Study:

• To develop a cheap, environmentally friendly, wet chemical deposition process for large-sized, few-layer MoS2 flakes.
• To demonstrate the feasibility of growing MoS2 in an aqueous solution for potential large-scale production.

Main Methods:

• Utilized ammonium tetrathiomolybdate (ATTM) dissolved in deionized water as a precursor solution.
• Employed a Langmuir-Blodgett-like deposition process on a SiO2/Si substrate.
• Applied thermal decomposition and characterized the resulting MoS2 flakes using Atomic Force Microscopy (AFM) and Raman spectroscopy.

Main Results:

• Successfully produced large-sized MoS2 flakes with lateral dimensions exceeding 150 μm.
• Confirmed flake thicknesses ranging from monolayer to five layers using AFM and Raman spectroscopy.
• Identified that post-growth thermal treatment and atmosphere significantly influence flake quality.

Conclusions:

• Presented a novel, simple, and non-toxic aqueous solution-based method for growing large MoS2 flakes.
• The developed technique is suitable for preparing large-scale hybrid transition metal dichalcogenide nanostructures for next-generation electronics.
• This approach addresses the critical need for scalable and affordable manufacturing of 2D materials.