Growth Substrate Void Formation for Nitride Semiconductor Strain
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Solution Overview
Problem
The growth of nitride semiconductor layers on silicon substrates is hindered by lattice constant and thermal expansion coefficient differences, leading to crystalline defects and strain, which affects the quality of light emitting devices.
Innovation Solution
A growth substrate with a silicon substrate, a first buffer layer, a second buffer layer causing a eutectic reaction with the substrate to form voids, and a third buffer layer to prevent further eutectic reactions, reducing strain and improving crystalline quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a nitride semiconductor layer is grown on a silicon substrate, then the manufacturing cost is reduced and productivity is improved, but crystalline defects occur due to lattice constant and thermal expansion coefficient differences
Solution Approach 1:
The buffer layer is divided into multiple segments with different compositions and thicknesses. The first buffer layer has a first thickness and aluminum content, the second buffer layer has a second thickness greater than the first and different aluminum content, creating a gradient structure that progressively manages strain and reduces dislocation density
Solution Approach 2:
The buffer layer uses composite material structure combining multiple nitride semiconductor layers with varying compositions. By controlling aluminum content and thickness in each layer, the structure achieves both mechanical strain management and crystalline quality improvement while maintaining compatibility with silicon substrate
2Manufacturing precision
If the aluminum content and thickness of buffer layers are increased to reduce strain, then crystalline quality improves, but device complexity and manufacturing steps increase
Solution Approach 1:
The invention optimizes specific parameters including aluminum content percentages and layer thicknesses to achieve the desired strain management. By carefully selecting these parameters, the buffer layer effectively reduces dislocation density without requiring excessive numbers of layers or impractical thickness values
Solution Approach 2:
Different regions of the buffer layer have different compositions and thicknesses tailored to local strain requirements. The gradient structure provides localized strain management where needed while maintaining overall structural 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 approach reduces strain caused by lattice constant differences, enabling the growth of high-quality nitride semiconductor layers and improving the overall quality of light emitting devices.
Implementation Method 1
a second buffer layer covering the first buffer layer and the exposed portions of the silicon substrate, wherein the second buffer layer is formed of a material causing a eutectic reaction with the silicon substrate
Data Source
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AI summary
Disclosed are a growth substrate and a light emitting device. The light emitting device includes a silicon substrate, a first buffer layer disposed on the silicon substrate and having an exposing portions of the silicon substrate, a second buffer layer covering the first buffer layer and the exposed portions of the silicon substrate, wherein the second buffer layer is formed of a material causing a eutectic reaction with the silicon substrate, a third buffer layer disposed on the second buffer layer, and a light emitting structure disposed on the third buffer layer, and the second buffer layer includes voids.