Nitride Semiconductor Light-Emitting Element Threading Dislocation Reduction
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Solution Overview
Problem
Nitride semiconductor light-emitting elements face limitations in reducing threading dislocation density, which affects their thermal characteristics and luminous efficiency, especially at high temperatures, and existing strained-layer superlattice structures are not effective in achieving this.
Innovation Solution
A multilayer body of n-type nitride semiconductor layers with different band-gap energies and thicknesses is introduced between the n-type and light-emitting layers, along with V-pits in the light-emitting layer, to deflect threading dislocations and enhance crystallinity and luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a strained-layer superlattice structure is used under the light-emitting layer, then strain relaxation is improved, but threading dislocation density reduction is insufficient
Solution Approach 1:
The patent divides the underlying layer into multiple alternating layers of first nitride semiconductor layers and second nitride semiconductor layers with different band-gap energies. This segmentation creates multiple interfaces that effectively deflect threading dislocations, reducing their density in the light-emitting layer while maintaining strain relaxation.
Solution Approach 2:
The patent applies local quality by creating regions with different band-gap energies through alternating nitride semiconductor layers. Each interface between layers with different band-gap energies serves as a local defect-deflection zone, selectively targeting threading dislocation reduction without compromising overall strain relaxation.
2Reliability
If the first and second nitride semiconductor layers have thicknesses of more than 10 nm and 30 nm or less, then threading dislocation deflection is optimized, but layer structure complexity increases
Solution Approach 1:
The patent optimizes the thickness parameters of the first and second nitride semiconductor layers to specific ranges (more than 10 nm and 30 nm or less, respectively). These parameter changes maximize the deflection effect on threading dislocations while maintaining manufacturability and avoiding excessive structural complexity.
3Loss of energy
If AlGaN barrier layers are used to increase band-gap energy difference, then luminous efficiency is enhanced, but crystal growth quality deteriorates
Solution Approach 1:
The patent uses composite nitride semiconductor structures with alternating layers of different materials (first and second nitride semiconductor layers with different band-gap energies). This composite approach achieves high luminous efficiency through band-gap engineering while maintaining crystal growth quality by avoiding the difficulties associated with AlGaN growth.
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 significantly reduces threading dislocation density and improves the thermal characteristics and luminous efficiency of nitride semiconductor light-emitting elements, maintaining high efficiency even at elevated temperatures.
Implementation Method 1
each of the first and second nitride semiconductor layers having a thickness of more than 10 nm and 30 nm or less, the light-emitting layer has a reduced density of threading dislocations as a result of threading dislocations being deflected at the interfaces between layers with different band-gap energies
Implementation Method 2
When voltage is applied to the nitride semiconductor light-emitting element, electrons and holes are recombined in a well layer as a component of the light-emitting layer and generate light
Implementation Method 3
Another disclosed structure is aimed at improving optical power and reducing leakage current and includes V-pits created in an upper portion of an n-type nitride semiconductor layer
Data Source
AI summary
A nitride semiconductor light-emitting element includes at least an n-type nitride semiconductor layer, a light-emitting layer, and a p-type nitride semiconductor layer. A multilayer body is provided between the n-type nitride semiconductor layer and the light-emitting layer, having at least one stack of first and second semiconductor layers. The second semiconductor layer has a greater band-gap energy than the first semiconductor layer. The first and second semiconductor layers each have a thickness of more than 10 nm and 30 nm or less. In applications in which luminous efficiency at room temperature is a high priority, the first semiconductor layer has a thickness of more than 10 nm and 30 nm or less, the second semiconductor layer has a thickness of more than 10 nm and 40 nm or less, and the light-emitting layer has V-shaped recesses in cross-sectional view.