SiC Substrate Graphene Film Mobility Control
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Solution Overview
Problem
The mobility of graphene films used in electronic devices formed on silicon carbide substrates is often lower than expected, making it difficult to achieve high switching speeds and efficient mass production.
Innovation Solution
A stacked body with a silicon carbide substrate having a main surface angle of 20° or less with a carbon plane and a graphene film oriented in relation to the substrate's atomic arrangement, reducing regions with thicker graphene layers to enhance mobility, with 10 or less regions per 1 mm², each with 10 or more layers and a diameter of 5 μm to 100 μm, and covering 80% or more of the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a graphene film is formed on a large-diameter support substrate through bonding, then the substrate area is increased for mass production, but large regions without graphene film remain making automation difficult
Solution Approach 1:
The invention changes the formation method parameter from bonding external graphene films to in-situ growth on the substrate. This parameter change ensures complete coverage of the large-diameter substrate surface with graphene film, eliminating the large uncovered regions that prevent automation in conventional bonding methods.
2Area of stationary object
If a SiC substrate is heated to desorb Si atoms and transform the surface layer into graphene, then the region without graphene film is reduced, but the graphene film thickness becomes non-uniform with thick regions
Solution Approach 1:
The invention applies preliminary action by controlling the heating process parameters before complete graphene formation occurs. By carefully managing the heating conditions and duration, the transformation of SiC surface layer into graphene is controlled to achieve uniform thin film formation rather than thick non-uniform regions.
Solution Approach 2:
The invention changes the heating parameter control to achieve precise temperature management during SiC decomposition. This parameter optimization ensures that graphene forms as a uniform thin layer rather than thick regions, resolving the uniformity problem while maintaining high coverage area.
3Area of stationary object
If the graphene film is formed with thick regions to ensure coverage, then the coverage area is increased, but the carrier mobility decreases
Solution Approach 1:
The invention changes the critical parameter of graphene film thickness from thick to thin through controlled heating parameters. This parameter optimization achieves the dual benefit of maintaining high coverage area while ensuring thin uniform thickness that preserves high carrier mobility of 5000 cm²/Vs or more.
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 configuration ensures high mobility in electronic devices, facilitating mass production by reducing the area without the graphene film and increasing switching speed with carrier mobility of 5000 cm²/Vs or more.
Implementation Method 1
a method has been proposed according to which a substrate made of SiC (silicon carbide) is heated to desorb Si atoms and thereby transform a surface layer of the substrate into graphene
Data Source
AI summary
A stacked body includes: a substrate made of silicon carbide and having a first main surface forming an angle of 20° or less with a carbon plane; and a graphene film disposed on the first main surface and having an atomic arrangement oriented in relation to an atomic arrangement of silicon carbide forming the substrate. In an exposed surface of the graphene film as seen in plan view, 10 or less regions are present per 1 mm2, the exposed surface being a main surface opposite to the substrate, and the regions each including 10 or more graphene layers and having a circumcircle with a diameter of 5 μm or more and 100 μm or less. Accordingly, the stacked body is provided that enables a high mobility to be stably ensured in an electronic device manufactured to include the graphene film forming an electrically conductive portion.