AlInN Buffer Layer Lattice Control for GaN Crystallinity
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Solution Overview
Problem
Existing methods for growing Group III nitride semiconductor crystals on substrates like sapphire and SiC face challenges due to large lattice mismatch, leading to poor crystallinity and light emission efficiency, with existing buffer layers not effectively addressing dislocation issues and productivity concerns.
Innovation Solution
A Group III nitride semiconductor device with a buffer layer made of AlN, where the lattice constants are controlled to satisfy a specific relationship, ensuring good orientation and uniformity, and a ground layer of GaN is formed using an MOCVD method, resulting in improved crystallinity and light-emitting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low temperature buffer layer made of AlN or AlGaN is laminated on a substrate to enable epitaxial growth, then the crystal can be grown on the substrate, but the lattice match is not achieved and threading dislocations are generated
Solution Approach 1:
The invention changes the composition parameters of the buffer layer by introducing InN into AlN to form an AlInN buffer layer. By adjusting the In composition ratio, the lattice constant of the buffer layer is modified to achieve better lattice matching with both the sapphire substrate and the GaN crystal layer, thereby reducing threading dislocations while maintaining crystal growth capability
Solution Approach 2:
The invention creates a composite buffer layer structure consisting of AlInN with specific composition ratios. This composite material combines the advantages of AlN (good lattice matching with sapphire) and InN (good lattice matching with GaN), enabling simultaneous optimization of interface matching at both substrate and crystal interfaces
2Stability of the object's composition
If a buffer layer is formed by high frequency sputtering to achieve stable crystal lamination, then crystal stability improves, but the crystallinity of the (10-10) plane of the GaN ground layer remains poor
Solution Approach 1:
The invention optimizes the composition parameters of the AlInN buffer layer by controlling the In content within specific ranges (0.01≤x≤0.20 in Al1-xInxN). This parameter optimization simultaneously improves both the stability of crystal lamination and the crystallinity of the GaN (10-10) plane by achieving better lattice matching without excessive lattice constant deviation
3Manufacturing precision
If the lattice constant of the buffer layer is reduced to improve orientation, then the uniformity of the buffer layer improves, but the dislocation density increases
Solution Approach 1:
The invention optimizes the In composition ratio in the AlInN buffer layer to achieve the optimal balance between lattice constant and dislocation density. By controlling x within 0.01≤x≤0.20, the lattice constant is reduced sufficiently to improve orientation and uniformity, while avoiding excessive reduction that would cause misfit dislocations
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 approach results in a Group III nitride semiconductor with enhanced device properties and light-emitting performance by achieving better lattice matching and reducing dislocation density, thereby improving the overall quality of the semiconductor layer.
Implementation Method 1
the buffer layer is formed by using plasma to activate and react a Group V element-containing gas and a metal material
Implementation Method 2
a vapor of a raw material is introduced into a carrier gas to convey the vapor to the surface of a substrate and decompose the raw material on the surface of the heated substrate, to thereby grow a crystal
Data Source
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AI summary
A Group III nitride semiconductor device of the present invention is obtained by laminating at least a buffer layer (12) made of a Group III nitride compound on a substrate (11), wherein the buffer layer (12) is made of AlN, and a lattice constant of a-axis of the buffer layer (12) is smaller than a lattice constant of a-axis of AlN in a bulk state.