Group III Nitride Semiconductor Structure for Mg Diffusion Suppression
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Solution Overview
Problem
The epitaxial growth of group III nitride semiconductor layers on substrates like ScAlMgO4 leads to Mg incorporation into the semiconductor layer, causing defects and reducing crystal quality due to lattice mismatch and thermal expansion differences.
Innovation Solution
Incorporating an InGaN layer to control Mg diffusion, adjusting the lattice constant of the GaN layer and suppressing Mg incorporation, thereby enhancing crystal quality and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a ScAlMgO4 substrate is used for epitaxial growth of group III nitride semiconductor, then lattice mismatch is reduced and defect density decreases, but Mg is incorporated into the semiconductor layer causing deterioration in characteristics
Solution Approach 1:
An InGaN layer is introduced as an intermediary between the ScAlMgO4 substrate and the GaN layer. This intermediate layer acts as a buffer that prevents Mg diffusion from the substrate into the GaN layer while maintaining the lattice matching benefits of the ScAlMgO4 substrate. The InGaN layer selectively allows lattice constant adjustment without permitting Mg incorporation into the functional GaN layer.
Solution Approach 2:
The semiconductor structure is segmented into multiple functional layers: the ScAlMgO4 substrate provides lattice matching, the InGaN intermediate layer prevents Mg diffusion, and the GaN layer provides the desired semiconductor properties. This segmentation allows each layer to perform its specific function without interfering with the others, solving both the lattice mismatch and Mg incorporation problems.
2Reliability
If the lattice constant difference between substrate and group III nitride crystal is reduced, then crystal quality is improved, but Mg diffusion into the semiconductor layer increases
Solution Approach 1:
The InGaN layer serves as a mediator that decouples the relationship between lattice matching and Mg diffusion. It allows the system to achieve good lattice matching through the ScAlMgO4 substrate while simultaneously blocking Mg diffusion pathways to the GaN layer, thus improving crystal quality without the harmful side effect of Mg incorporation.
3Ease of manufacture
If GaN is epitaxially grown on sapphire substrate, then device production is simplified, but lattice mismatch of 13.8% causes increased defect density and cracks
Solution Approach 1:
The patent introduces an InGaN intermediate layer between the sapphire substrate and the GaN layer. This intermediary layer compensates for the large lattice mismatch by providing a gradual transition in lattice constants, thereby reducing defect density and crack formation while maintaining the ease of using readily available sapphire substrates.
Solution Approach 2:
The InGaN layer allows for parameter changes in lattice constant by adjusting the Indium composition. This compositional tuning enables the intermediate layer to bridge the large lattice mismatch between sapphire and GaN, reducing defects while maintaining manufacturing 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
The InGaN layer effectively limits Mg diffusion, maintaining a high-quality semiconductor structure with reduced defects and improved lattice matching, resulting in enhanced light-emitting device performance.
Implementation Method 1
an InGaN layer can suppress Mg from being diffused into the functional layer
Implementation Method 2
Mg as a constituent element of the ScAlMgO4 substrate to be incorporated into the group III nitride semiconductor layer. Moreover, the ScAlMgO4 substrate has a lattice constant close to the lattice constant of GaN, but has a lower lattice constant than the lattice constant of GaN
Data Source
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AI summary
To provide a high-quality group III nitride semiconductor. A group III nitride semiconductor including an n-GaN layer composed of AlxGa1-xN (0 ≤ x < 1), an InGaN layer disposed on the n-GaN layer and composed of InGaN, an n-AlGaN layer disposed on the InGaN layer and composed of n-type AlyGa1-yN (0 ≤ y < 1), and a functional layer disposed on the n-AlGaN layer, wherein the concentration of Mg in the n-GaN layer is higher than the concentration of Mg in the n-AlGaN layer.