GaN Film Growth via Graphene and Sputtered AlN Buffer
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Solution Overview
Problem
The growth of high-quality gallium nitride is hindered by high dislocation density due to lattice and thermal mismatch with substrates, and existing methods face challenges with costly substrates, poor graphene quality, and difficulty in nucleating nitride layers, limiting the performance and reliability of GaN-based devices.
Innovation Solution
A method involving the use of graphene as a buffer layer and magnetron sputtering of aluminum nitride to create a nucleation layer, followed by metal organic chemical vapor deposition (MOCVD) to grow gallium nitride layers with varying V-III ratios, addressing lattice mismatch and improving material quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heteroepitaxial growth is used to grow gallium nitride on conventional substrates, then the production cost is reduced and manufacturing is simplified, but the dislocation density becomes very high due to lattice mismatch and thermal mismatch
Solution Approach 1:
The patent introduces graphene as an intermediary buffer layer between the substrate and gallium nitride epitaxial layer. This mediator resolves the lattice mismatch and thermal expansion coefficient mismatch problems by providing a transition interface with compatible properties, thereby reducing dislocation density while maintaining manufacturing feasibility
Solution Approach 2:
The patent creates a composite structure consisting of substrate + graphene buffer layer + thin nitride layer + gallium nitride epitaxial layer. This multi-layer composite approach combines the advantages of different materials to achieve low dislocation density in the final GaN layer while keeping the overall manufacturing process practical
2Reliability
If silicon carbide substrate is used with graphene buffer layer, then the dislocation density is reduced and crystal quality is improved, but the production cost increases significantly
Solution Approach 1:
The patent changes the substrate material parameter from expensive silicon carbide to more cost-effective alternatives, while compensating for the potential quality loss by optimizing the graphene buffer layer and thin nitride layer parameters. This maintains crystal quality through parameter optimization rather than relying solely on expensive substrates
3Manufacturing precision
If thin nitride layer is directly inserted between graphene and gallium nitride, then the lattice mismatch is alleviated, but the nucleation becomes difficult and crystal quality deteriorates
Solution Approach 1:
The patent applies preliminary actions by first growing a high-quality graphene buffer layer on the substrate, and then inserting a thin nitride layer that is pre-optimized for nucleation. This preliminary preparation of the interface structure ensures that subsequent gallium nitride growth occurs on a well-prepared surface, facilitating nucleation and maintaining crystal quality
4Ease of manufacture
If epitaxial growth temperature is limited below copper melting point, then the growth process is simplified and no impurities are introduced, but the aluminum nitride nucleation layer quality becomes poor due to insufficient temperature
Solution Approach 1:
The patent segments the growth process into distinct stages: first growing the graphene buffer layer at controlled temperature, then forming the thin nitride layer, and finally growing the gallium nitride epitaxial layer. This segmentation allows each stage to be optimized independently, ensuring nucleation layer quality without compromising overall process simplicity
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 reduces dislocation density and enhances the quality of gallium nitride films, allowing for improved performance and reliability of GaN-based devices by effectively alleviating lattice and thermal mismatch issues.
Implementation Method 1
spreading graphene over a substrate
Implementation Method 2
magnetron sputtering aluminum nitride onto the graphene-coated substrate
Implementation Method 3
heat treating the substrate to obtain the heat-treated substrate
Implementation Method 4
growing a first gallium nitride layer and a second gallium nitride layer on the heat-treated substrate
Data Source
AI summary
The present invention discloses a method for growing gallium nitride based on graphene and magnetron sputtered aluminum nitride, and a gallium nitride thin film. The method according to an embodiment comprises: spreading graphene over a substrate; magnetron sputtering an aluminum nitrite onto the graphene-coated substrate to obtain a substrate sputtered with aluminum nitrite; placing the substrate sputtered with aluminum nitride into a MOCVD reaction chamber and heat treating the substrate to obtain a heat treated substrate; growing an aluminum nitride transition layer on the heat treated substrate and a first and a second gallium nitride layer having different V-III ratios, respectively. The gallium nitrate thin film according to an embodiment comprises the following structures in order from bottom to top: a substrate (1), a graphene layer (2), an aluminum nitride nucleation layer (3) fabricated by using a magnetron sputtering method, an aluminum nitride transition layer (4) grown by MOCVD, and a first and a second gallium nitrate layer (5, 6) having different V-III ratios.