InGaN Strain Relaxation Layer for Thin GaN Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Producing high-quality group III nitride compound semiconductor light emitting devices is challenging due to dislocation issues when using thin GaN substrates, which are expensive and prone to strain-related dislocation, affecting the crystal quality of the nitride compound semiconductor.
Innovation Solution
A group III nitride compound semiconductor light emitting device is developed using a thin GaN substrate with a support substrate, featuring an InGaN strain relaxation layer with an In composition ratio between 0% to 3%, which reduces lattice constant differences and minimizes dislocation, and a method involving epitaxial growth using MOCVD to form conductive semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thin GaN substrate is used as a growth substrate, then production cost is reduced and substrate handling is easier, but dislocation occurs easily in the InGaN layer due to strain
Solution Approach 1:
The patent changes the compositional parameter of the InGaN layer by controlling the indium composition ratio to be 3% or less. This parameter adjustment reduces the lattice constant difference between the InGaN layer and the GaN substrate, thereby reducing strain and preventing dislocation while allowing the use of thin, cost-effective substrates
Solution Approach 2:
The patent employs a composite structure consisting of a GaN substrate combined with an InGaN layer having specific compositional characteristics. This composite approach allows the system to benefit from both the mechanical properties of the GaN substrate and the optimized optical/electrical properties of the low-indium-content InGaN layer, achieving both cost reduction and dislocation prevention
2Illumination intensity
If the In composition ratio in the InGaN layer is increased, then light emitting properties are improved, but lattice constant difference increases causing stress concentration and dislocation
Solution Approach 1:
The patent optimizes the indium composition ratio parameter to be within 0-3%, finding the optimal balance point where light emitting properties are sufficiently maintained while lattice constant difference and strain are kept below dislocation-threshold levels. This precise parameter control resolves the contradiction between optical performance and crystal quality
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 solution effectively inhibits dislocation in the strain relaxation layer, improving the crystal quality and radiant flux of the light emitting device, even when using a thin GaN substrate, by relaxing stress concentrations and maintaining high crystallinity.
Implementation Method 1
difference in lattice constant between the thin GaN substrate and the InGaN layer is small. Therefore, stress concentration due to the difference in lattice constant can be relaxed
Implementation Method 2
stress concentration due to the difference in lattice constant can be relaxed. As a result, occurrence of dislocation due to stress concentration can be inhibited
Implementation Method 3
a vapor phase epitaxial method such as a metal organic chemical vapor deposition method (MOCVD)
Implementation Method 4
a vapor phase epitaxial method such as a metal organic chemical vapor deposition method (MOCVD)
Data Source
AI summary
A group III nitride compound semiconductor light emitting device that inhibits occurrence of dislocation in a strain relaxation layer in forming a group III nitride compound semiconductor layer on a thin GaN substrate, and a method for producing the same are provided. A light emitting device 100 comprises a support substrate 10, a GaN substrate 20, an n-type contact layer 30, a strain relaxation layer 40 (n-type InGaN layer), a light emitting layer 50, a p-type clad layer 60, and a p-type contact layer 70. The GaN substrate 20 has a thickness in a range of from 10 nm to 10 μm. The strain relaxation layer 40 (n-type InGaN layer) has an In composition ratio X in a range of from larger than 0 to 3%.