Liquid Eutectic Substrate for High-Speed Graphene CVD
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Solution Overview
Problem
The production of large area, single crystal graphene by chemical vapour deposition (CVD) is hindered by low growth rates and the influence of substrate topography, requiring costly and time-consuming substrate preparation methods, and limited scalability of expensive single crystal substrates.
Innovation Solution
A process using a substrate with a liquid surface formed by a molten eutectic compound, which minimizes substrate topographic defects and allows graphene to grow in its natural shape, achieving high growth rates and reducing the need for conventional substrate preparation steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional solid substrates are used with CVD, then substrate control over growth is achieved, but growth rates are limited to low values (up to 5 μm/min) and substrate defects strongly influence graphene quality
Solution Approach 1:
The invention changes the physical state parameter of the substrate from solid to liquid by using a molten eutectic compound. This parameter change fundamentally alters the substrate-graphene interaction, allowing graphene to grow on a liquid surface that does not impose crystallographic constraints or topographic defects, thereby achieving both high growth rates and high graphene quality simultaneously
Solution Approach 2:
The molten eutectic compound acts as an intermediary between the solid substrate and the growing graphene. It screens the substrate's crystallographic lattice and defects from influencing graphene growth, allowing graphene to achieve its natural hexagonal shape and high crystallinity while enabling much faster growth rates than direct solid substrate growth
2Manufacturing precision
If substrate preparation methods (annealing, polishing, etching) are used to improve surface quality, then graphene crystallinity is enhanced, but process time and energy consumption increase significantly
Solution Approach 1:
The invention extracts the problematic substrate surface preparation steps entirely from the process by using a liquid substrate. Since the liquid surface naturally lacks topographic defects and crystallographic constraints, methods like annealing, polishing, and etching become unnecessary, dramatically reducing process time and energy consumption while maintaining high graphene crystallinity
Solution Approach 2:
The liquid substrate surface acts as a temporary, disposable growth medium. After graphene growth, the liquid surface can be easily discarded or regenerated without requiring time-consuming restoration processes, eliminating the need for repeated substrate preparation cycles
3Manufacturing precision
If expensive single crystal substrates are used, then large area single crystal graphene can be produced, but scalability is limited due to substrate size constraints and high cost
Solution Approach 1:
The liquid substrate provides universal growth conditions that are independent of substrate size or crystallographic orientation. Any solid substrate can be used as long as it can support the molten eutectic compound, making the system universally applicable and scalable to large areas without requiring expensive single crystal substrates or limiting the graphene area to substrate grain boundaries
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of high-quality, millimeter-sized graphene flakes in short time periods with low nucleation density, improving crystallinity and allowing for the reuse of substrates, thus overcoming the limitations of traditional methods.
Implementation Method 1
a surface which is a liquid surface formed by a molten eutectic compound
Implementation Method 2
forming the two-dimensional nanomaterial on a surface of a substrate by CVD
Data Source
AI summary
The present invention provides a process for producing a two-dimensional nanomaterial, the process comprising forming the two-dimensional nanomaterial on a surface of a substrate by CVD, wherein said surface is a liquid surface which comprises a molten eutectic compound. Substrates and substrate precursors for use in said process are also provided.