Nitride Semiconductor Light Emitting Element with Al Composition Gradient
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Solution Overview
Problem
Current light emitting elements face challenges in achieving high light extraction efficiency due to limitations in semiconductor layer thickness and AlGaN-based designs, which affect light absorption and conductivity.
Innovation Solution
A light emitting element design featuring a nitride semiconductor stack with varying Al percentage compositions in its layers, where the first conductivity type semiconductor layer has a lower Al percentage in one region for reduced light absorption and a higher Al percentage in another region for improved conductivity, along with specific layer thickness and surface roughening to enhance light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of the semiconductor layer is reduced to improve light extraction efficiency, then light extraction efficiency is improved, but mechanical strength and reliability deteriorate
Solution Approach 1:
The patent applies local quality by creating different thickness regions within the semiconductor layer. The light extraction region has a reduced thickness to improve light extraction efficiency, while other regions maintain sufficient thickness to ensure mechanical strength and reliability. This spatial variation in thickness allows simultaneous optimization of both light extraction and structural integrity.
2Reliability
If the Al percentage composition is increased to improve conductivity, then electrical conductivity is improved, but light absorption increases reducing light extraction efficiency
Solution Approach 1:
The patent implements local quality by varying the Al percentage composition across different regions of the semiconductor layer. Regions requiring high conductivity have higher Al content, while regions where light extraction is prioritized have lower Al content to minimize light absorption. This compositional gradient allows simultaneous optimization of electrical and optical properties.
Solution Approach 2:
The semiconductor layer is segmented into multiple regions with different Al compositions. This segmentation enables independent optimization of each region's properties - some regions are designed for electrical conductivity with higher Al content, while others are designed for light extraction with lower Al content, thereby resolving the contradiction between these two requirements.
3Loss of energy
If the semiconductor layer thickness is partially reduced, then light extraction efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent divides the semiconductor layer into distinct thickness regions - a light extraction region with reduced thickness and other regions with standard thickness. This segmentation allows the reduced thickness to be implemented only where needed for light extraction, while maintaining sufficient thickness elsewhere, thereby reducing the overall manufacturing precision burden compared to uniformly thinning the entire layer.
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 design improves light extraction efficiency by minimizing light absorption in the first region and reducing forward voltage and crack occurrence, while maintaining effective conductivity and reducing current concentration.
Implementation Method 1
An Al percentage composition of the first layer is lower than an Al percentage composition of the second layer. The first conductivity type semiconductor layer comprises: a first region where the second conductivity type semiconductor layer and the active layer are stacked; and a second region exposed from the second conductivity type semiconductor layer and the active layer.
Data Source
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AI summary
A light emitting element includes a first conductivity type semiconductor layer that is a nitride semiconductor layer containing A1 and Ga. The first conductivity type semiconductor layer includes a first layer and a second layer. An Al percentage composition of the first layer is lower than an A1 percentage composition of the second layer. The first conductivity type semiconductor layer has a first region and a second region. The first region is a region where the second conductivity type semiconductor layer and the active layer are stacked. The second region is exposed from the second conductivity type semiconductor layer and the active layer, and is connected to a first conductive member. A thickness of the first layer in the first region is smaller than a thickness of the first layer in the second region, or the second layer is exposed from the first layer in the first region.