Graphene Mesh Deposition Using CO Plasma on Heated Substrates
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Solution Overview
Problem
Current methods for depositing carbon nanostructures, such as graphene sheets, face challenges in achieving high-quality deposition on arbitrary substrates with efficient growth rates and scalability, often resulting in low-quality coatings with amorphous carbon, diamond crystallites, or soot when deposition times exceed a short duration.
Innovation Solution
The method involves using a processing chamber with carbon monoxide gas and sustaining gaseous plasma at high power density to dissociate CO molecules into C and O atoms, which are then deposited onto a substrate heated above 500 °C, allowing for the growth of high-quality carbon nanostructures without catalysts and maintaining chamber wall temperatures below 300 °C to prevent CO molecule association.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma methods are used for depositing carbon nanostructures, then deposition can be achieved, but the quality degrades to amorphous carbon, diamond crystallites, or soot when deposition times exceed a short duration
Solution Approach 1:
The invention changes the chemical composition parameter of the processing gas from conventional hydrocarbons (methane, ethylene) to carbon monoxide (CO). This parameter change enables high-quality graphene sheet deposition to be sustained over longer deposition times without degrading to amorphous carbon or soot, directly resolving the contradiction between deposition quality and deposition time duration
Solution Approach 2:
The invention uses carbon monoxide in a controlled atmosphere with specific pressure (1-1000 Pa) and temperature conditions to create an inert-like environment that prevents unwanted carbon phase formation. This controlled atmosphere allows prolonged deposition while maintaining high-quality crystalline graphene structures, addressing the quality degradation issue over time
2Productivity
If high power density plasma is used to enable rapid deposition, then productivity increases, but chamber wall temperature rises which causes CO molecules to associate and deposit on walls instead of substrate
Solution Approach 1:
The invention applies local quality by heating only the substrate to above 500°C while maintaining chamber walls below 300°C. This localized temperature control ensures that CO dissociation and graphene growth occur only at the substrate surface where high quality nanostructures are desired, while chamber walls remain cool enough to prevent unwanted CO association and deposition, enabling rapid deposition without wall contamination
Solution Approach 2:
The invention segments the thermal zones within the processing chamber by using independent heating control for the substrate and chamber walls. This segmentation allows the substrate to be in a high-temperature zone for rapid graphene growth while chamber walls remain in a low-temperature zone to prevent CO molecule association, resolving the contradiction between productivity and temperature control
3Manufacturing precision
If substrate temperature is raised above 500°C to promote graphene growth, then manufacturing precision improves, but energy consumption increases
Solution Approach 1:
The invention changes the processing gas parameter to carbon monoxide, which has higher dissociation energy and forms more stable carbon structures at elevated temperatures. This parameter change enables the substrate to be heated above 500°C to promote high-quality graphene growth while the energy is more efficiently utilized for creating desired nanostructures rather than forming unwanted phases, improving the energy efficiency of high-temperature processing
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 rapid and scalable deposition of high-quality carbon nanostructures with a high percentage of randomly oriented graphene sheets, suitable for applications like radiation absorption and energy storage devices, while avoiding unwanted carbon forms.
Implementation Method 1
creating and sustaining gaseous plasma in the processing chamber for a period of at least 1 second, the gaseous plasma having a power density of at least 0.1 MW m-3
Implementation Method 2
the gaseous plasma having a power density of at least 0.1 MW m-3 which is sufficient to dissociate CO molecules into C and O atoms
Implementation Method 3
the C and O atoms are then deposited onto a substrate heated above 500 °C
Implementation Method 4
allowing for the growth of high-quality carbon nanostructures without catalysts
Implementation Method 5
maintaining chamber wall temperatures below 300 °C to prevent CO molecule association
Data Source
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AI summary
The present invention relates to methods and apparatus for depositing carbon nanostructures such as three-dimensional graphene mesh using non-equilibrium gaseous plasma of high power density. Methods are disclosed for rapid deposition of randomly distributed graphene sheets on surfaces of substrates using decomposition of CO molecules of a high potential energy, and said excited CO molecules interacting with a substrate. Another method uses a carbon containing precursor in condensed form and a processing gas comprising oxygen or an oxygen containing gas. The three-dimensional graphene mesh prepared according to the methods of invention is useful in different applications such as light absorbents, fuel cells, super- capacitors, batteries, photovoltaic devices and sensors of specific gaseous molecules.