UV LED Quantum Well Stress Management
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Solution Overview
Problem
Current UV light-emitting diodes have low luminous efficiency and struggle to replace mercury lamps effectively due to high lattice dislocations and defects, which hinder their industrial applications.
Innovation Solution
A UV light-emitting diode structure is designed with a patterned substrate, specific semiconductor layers, and multiple quantum wells to reduce lattice mismatch and defects, incorporating a template layer with aluminum nitride and growth layers with varying aluminum content to enhance stress management and electron blocking, leading to improved luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional UV light-emitting diode structures are used, then the device can be manufactured with standard processes, but the luminous efficiency remains low due to high lattice dislocations and defects
Solution Approach 1:
The patent segments the active region into multiple quantum well layers (five or more periods of well layers and barrier layers) with varying aluminum contents. This segmentation allows each layer to be optimized independently for stress management and carrier confinement, reducing overall lattice dislocation density while maintaining high luminous efficiency through cumulative light emission from multiple interfaces.
Solution Approach 2:
The patent applies local quality by creating spatial variation in aluminum content across different layers - the well layers have lower aluminum content (30-40%) for better electron mobility, while barrier layers have higher aluminum content (40-50%) for better hole confinement. This local optimization of material composition at different positions resolves the contradiction by allowing each region to contribute differently to overall performance.
2Illumination intensity
If the number of stacked layers is increased to improve light emission, then the luminous intensity increases, but the manufacturing complexity and stress management difficulty increase
Solution Approach 1:
The patent employs periodic action by repeating the quantum well structure five or more times with alternating well layers and barrier layers. This periodic repetition systematically increases light-emitting intensity through cumulative emission from each period while maintaining manageable complexity through modular design - each period can be grown using the same cyclic deposition process parameters.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying the aluminum content parameter across different layers and periods. The aluminum content is adjusted within specific ranges (30-40% for well layers, 40-50% for barrier layers) to optimize both stress distribution and optical properties, allowing increased layer count without proportionally increasing manufacturing difficulty.
3Reliability
If aluminum content is varied across layers to reduce stress, then lattice mismatch is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-planning the aluminum content gradient across layers before fabrication. The aluminum content is deliberately designed to follow specific ranges (30-40% for well layers, 40-50% for barrier layers) to proactively manage stress and lattice mismatch before growth begins, rather than attempting to correct issues after fabrication.
Solution Approach 2:
The patent manages manufacturing precision by establishing acceptable parameter ranges rather than requiring exact values. The aluminum content is controlled within 30-40% for well layers and 40-50% for barrier layers, providing a tolerance window that accommodates normal manufacturing variations while still achieving the desired stress reduction and lattice matching effects.
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 reduces lattice dislocations, increases the number of stacked layers, and enhances electron injection efficiency, resulting in higher light-emitting intensity and reduced light attenuation, making it suitable for replacing mercury lamps in applications like medical sterilization.
Implementation Method 1
a plurality of layers of multiple quantum wells include n-type aluminum gallium nitride
Implementation Method 2
The patterned substrate does indeed improve the stress between the patterned substrate and the template layer, indirectly improving the stress on the stacked layer above the template layer, thereby reducing lattice dislocations and lattice defects
Implementation Method 3
a first electron blocking layer, a second electron blocking layer
Data Source
AI summary
An UV light-emitting diode includes a patterned substrate, a template layer, a growth layer, a first n-type semiconductor layer, an intrinsic semiconductor layer, a second n-type semiconductor layer, a plurality of layers of multiple quantum wells, a barrier layer, a first electron blocking layer, a second electron blocking layer, a first p-type semiconductor layer and a second p-type semiconductor layer in sequence from a bottom layer to a top layer. Whereas the aforementioned layers all include Group III nitride materials and the number of layers for the plurality of layers of multiple quantum wells is at least five layers. Because the first n-type semiconductor layer, the first p-type semiconductor layer, and the plurality of layers of multiple quantum wells all contain aluminum, short-wavelength UV light is emitted when a current is applied.