Graphene Contact Deposition After Plasma Defect Removal
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Solution Overview
Problem
Graphene sheets produced by existing methods often have defects such as wrinkles and out-of-plane material, which affect their electrical and mechanical properties, making it challenging to achieve high-quality electrical contacts and sensitive biosensors.
Innovation Solution
A method involving targeted plasma etching to remove out-of-plane material from specific areas of the graphene layer structure, followed by depositing a material for charge injection or extraction, thereby improving electrical connections and biosensor sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphene is produced by high temperature CVD growth, then graphene can be formed on the substrate, but wrinkles and out-of-plane defects are created due to thermal expansion mismatch
Solution Approach 1:
The patent applies preliminary action by performing plasma treatment on the substrate surface before graphene deposition. This pre-treatment modifies the substrate surface properties to better match thermal expansion characteristics, preventing wrinkle formation during subsequent high-temperature CVD growth. The plasma treatment creates a surface layer that compensates for thermal expansion mismatch between graphene and substrate.
Solution Approach 2:
The patent changes physical parameters of the substrate surface through plasma treatment, modifying surface energy, roughness, and thermal properties. These parameter changes enable the substrate to better accommodate graphene during thermal cycling, reducing the formation of out-of-plane defects while maintaining high-temperature growth conditions.
2Ease of manufacture
If defects are present in graphene, then graphene can be produced by conventional methods, but electrical connectivity and contact quality deteriorate
Solution Approach 1:
The patent performs preliminary plasma treatment to remove surface contaminants and modify the substrate before graphene deposition. This prevents the formation of extrinsic defects caused by impurities and ensures better interface quality between graphene and substrate, improving electrical connectivity without complicating the manufacturing process.
Solution Approach 2:
The patent replaces mechanical transfer methods with direct in-situ CVD growth on plasma-treated substrates. This eliminates mechanical damage and transfer-induced defects that commonly occur when transferring graphene from growth substrates to final substrates, thereby improving electrical connectivity while maintaining production feasibility.
3Ease of manufacture
If out-of-plane material is present on graphene surface, then defects are introduced, but contact deposition becomes difficult
Solution Approach 1:
The patent applies preliminary plasma treatment to flatten the graphene surface and remove out-of-plane material before contact deposition. This creates a smooth, defect-free surface that facilitates uniform contact material deposition and ensures high-quality electrical contacts without requiring additional complex processing steps.
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
The method enhances the electrical connectivity of contacts and improves the sensitivity of biosensors by removing defects and creating a flat planar surface for contact deposition, while maintaining the overall electrical continuity of the graphene sheet.
Implementation Method 1
plasma etching the one or more first portions of the graphene layer structure to remove the out-of-plane material
Implementation Method 2
depositing a material for injecting charge into, or extracting charge out of, the graphene layer structure onto the one or more plasma-etched first portions
Data Source
AI summary
The present invention relates to a method of forming a material on a graphene layer structure 5 for injecting charge into, or extracting charge out of, the graphene layer structure 5, the method comprising:providing a graphene layer structure 5 having one or more first portions 25 on a non-metallic substrate 10, said one or more first portions 25 having one or more surface defects comprising excess out-of-plane material 15; plasma etching the one or more first portions 25 of the graphene layer structure 5 to remove the out-of-plane material 15; depositing a material 30 for injecting charge into, or extracting charge out of, the graphene layer structure 5 onto the one or more plasma-etched first portions 25.