Wafer-scale and deterministic patterned growth of monolayer MoS₂via vapor-liquid-solid method

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Vapor transportation is critical for growing transition-metal dichalcogenides (TMDCs) via chemical vapor deposition (CVD).
• Spatial inhomogeneity of vapors in CVD leads to poor control over product properties like uniformity and reproducibility.
• Existing methods struggle with precise control over TMDC synthesis.

Purpose of the Study:

• To address the challenge of vapor inhomogeneity in TMDC synthesis.
• To develop a scalable and controlled method for producing high-quality TMDC monolayers.
• To demonstrate the efficacy of the vapor-liquid-solid (VLS) growth method for MoS2 synthesis.

Main Methods:

• Utilized the vapor-liquid-solid (VLS) growth mechanism involving molten precursors like sodium molybdate (Na2MoO4).
• Achieved supersaturation of sulfur vapor in the molten precursor to precipitate molybdenum disulfide (MoS2) monolayers.
• Employed VLS growth on SiO2/Si and sapphire substrates for different scales and morphologies.

Main Results:

• Demonstrated 4-inch wafer-scale uniform growth of MoS2 flakes on SiO2/Si substrates.
• Achieved 2-inch wafer-scale continuous MoS2 film growth with large grain sizes (>100 μm) on sapphire.
• Successfully realized patterned (site-controlled) growth of MoS2 flakes and films.

Conclusions:

• The VLS growth method effectively overcomes vapor inhomogeneity issues in TMDC synthesis.
• This approach enables high-efficiency and scalable production of two-dimensional TMDC monolayers.
• VLS growth offers a promising pathway for controlled synthesis of MoS2 and potentially other TMDCs.