Asymmetric Quantum Well Structure for High Current LED Efficiency
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Solution Overview
Problem
Semiconductor light emitting elements using group-III nitride semiconductors often experience reduced light emission efficiency, especially under high current density conditions, due to insufficient recombination of holes and electrons in the multiquantum well structure.
Innovation Solution
A semiconductor light emitting element with a light emitting layer comprising three or more well layers and four or more barrier layers, where the well layers have specific thicknesses and compositions to enhance light emission efficiency, maintaining unity of wavelength across the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multiquantum well structure with multiple well layers is used, then the light emission efficiency is improved, but the recombination of holes and electrons becomes insufficient under high current density conditions
Solution Approach 1:
The patent applies local quality by creating asymmetric well layers with different thicknesses within the quantum well structure. Specifically, the first well layer has a different thickness than the second well layer, allowing different regions of the light emitting layer to handle carrier recombination differently. This local variation in structure optimizes both light emission efficiency and carrier recombination completeness under high current density conditions.
Solution Approach 2:
The light emitting layer is segmented into multiple well layers (at least two different thicknesses) and barrier layers. This segmentation allows the structure to divide carrier injection and recombination processes across different regions, preventing carrier overflow and improving overall recombination efficiency while maintaining high light emission output.
2Productivity
If the well layer thickness is increased to improve light emission, then the wavelength unity of the output light is compromised
Solution Approach 1:
The patent changes structural parameters by introducing well layers with different thicknesses (first well layer thickness different from second well layer thickness) while carefully controlling the composition and thickness of barrier layers. This parameter variation allows different well layers to emit at slightly different wavelengths that combine to maintain overall wavelength unity, thereby improving light emission intensity without sacrificing spectral precision.
3Reliability
If more barrier layers are added to confine carriers, then the device complexity increases
Solution Approach 1:
The light emitting layer is segmented into multiple well layers separated by barrier layers. This segmentation provides effective carrier confinement through the barrier layers while maintaining a manageable structure. The alternating pattern of well and barrier layers creates a systematic design that confines carriers effectively without excessive complexity.
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 significantly increases light emission efficiency and maintains it in high current ranges while ensuring the unity of the light output wavelength, improving the performance of semiconductor light emitting elements.
Implementation Method 1
a light emitting layer that is stacked on the n-type semiconductor layer, is composed of a group-III nitride semiconductor, and emits light when being supplied with current
Data Source
AI summary
A semiconductor light emitting element includes an n-type semiconductor layer containing n-type impurities, a light emitting layer stacked on the n-type semiconductor layer, and a p-type semiconductor layer stacked on the light emitting layer and containing p-type impurities. The light emitting layer includes three or more well layers, and four or more barrier layers composed of a group-III nitride semiconductor having a larger band gap than that of the well layers, and each of the three or more well layers is sandwiched from both sides by neighboring two of the barrier layers. The three or more well layers include plural n-side well layers each having a first thickness to emit light of a common wavelength, and one or plural p-side well layers each having a second thickness larger than the first thickness and having a different composition from the n-side well layers to emit light of the common wavelength.