Wafer-Scale Synthesis of 2D Materials by an Amorphous Phase-Mediated Crystallization Approach

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Wafer-scale synthesis of 2D materials like transition metal dichalcogenides (TMDCs) is crucial for commercializing lab-scale devices.
• Pulsed laser deposition (PLD) shows promise for large-scale 2D material growth but often results in chalcogen deficiency and poor stoichiometry.
• Existing methods to address stoichiometry issues, such as adding excess chalcogen, lead to problems with uniformity and repeatability.

Purpose of the Study:

• To develop a novel approach for the wafer-scale synthesis of stoichiometric and crystalline 2D materials.
• To demonstrate a method that overcomes the limitations of traditional PLD for 2D material growth.
• To enable the large-scale production of 2D materials critical for next-generation electronic and optoelectronic devices.

Main Methods:

• Utilized a room-temperature pulsed laser deposition (PLD) process to create amorphous precursors with controlled thicknesses.
• Employed a post-deposition annealing step to crystallize the amorphous precursors into desired 2D materials.
• Investigated amorphous phase-mediated crystallization (APMC) for synthesizing materials like Molybdenum disulfide (MoS₂) and Tungsten diselenide (WSe₂).

Main Results:

• Successfully achieved wafer-scale synthesis of crystalline 2D materials, including MoS₂ and WSe₂, on Si/SiO₂ substrates.
• Demonstrated digital control over layer thickness by adjusting the number of laser pulses during PLD.
• Confirmed material stoichiometry and characterized crystalline quality, domain sizes, and layer numbers using advanced techniques (AFM, STEM, EDS).

Conclusions:

• The amorphous phase-mediated crystallization (APMC) approach effectively enables wafer-scale, stoichiometric synthesis of 2D materials.
• This technique offers a viable pathway for overcoming PLD limitations, paving the way for reproducible large-scale manufacturing.
• The developed growth method holds significant potential for integration into conventional semiconductor fabrication processes for advanced electronic and optoelectronic applications.