Patterned Electron Blocking Layer for LED Voltage and Luminance
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Solution Overview
Problem
Existing light emitting diodes (LEDs) face challenges in maintaining luminance intensity while improving operation voltage, particularly in low voltage/high power driving devices, where the epitaxial structure needs optimization to balance recombination efficiency and voltage requirements.
Innovation Solution
The LED design incorporates an n-type semiconductor layer with roughness and recessed portions, an electron blocking layer with patterned thickness variations, and an undoped semiconductor layer to planarize the surface, enhancing electron blocking and hole movement efficiency, thereby increasing luminance intensity and reducing operation voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the operation voltage is improved (reduced), then the LED becomes suitable for low voltage/high power driving, but the luminance intensity may deteriorate
Solution Approach 1:
The electron blocking layer is designed with patterned thickness variations (first region with greater thickness, second region with lesser thickness) to create local quality differences. This allows different regions to perform different functions: the thicker first region provides stronger electron blocking to reduce leakage current and lower operation voltage, while the thinner second region maintains good light extraction and luminance intensity.
2Illumination intensity
If the epitaxial structure is optimized to maintain luminance intensity, then the operation voltage improvement is limited, but if epitaxial structure is changed to improve operation voltage, then luminance intensity may deteriorate
Solution Approach 1:
The patent employs a composite epitaxial structure combining multiple semiconductor layers with different properties: n-type GaN layer, light emitting layer, patterned electron blocking layer, and p-type GaN layer. This composite structure integrates the benefits of each layer to simultaneously achieve low operation voltage and high luminance intensity.
Solution Approach 2:
The electron blocking layer introduces dynamic adaptability through its patterned thickness design, allowing the device to dynamically optimize electron blocking efficiency and light extraction based on the local structural characteristics, thereby achieving both low voltage operation and high luminance.
3Device complexity
If a uniform electron blocking layer is used, then the structure is simple, but electron blocking efficiency and hole movement efficiency cannot be simultaneously optimized
Solution Approach 1:
The electron blocking layer is designed with patterned thickness variations (first region with greater thickness, second region with lesser thickness) to create local quality differences. This allows different regions to perform different functions: the thicker first region provides stronger electron blocking to reduce leakage current and lower operation voltage, while the thinner second region maintains good light extraction and luminance intensity.
4Reliability
If the n-type semiconductor layer has roughness with recessed portions, then hole movement efficiency is improved, but the surface is non-planar requiring additional layers
Solution Approach 1:
The patent introduces controlled surface roughness parameters in the n-type GaN layer, creating recessed portions with specific depth and distribution. This parameter change improves hole movement efficiency by reducing dislocation-related resistance while the subsequent undoped layer planarizes the surface for subsequent processing.
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 configuration improves luminance intensity and reduces operation voltage by minimizing leakage current and dislocation-related resistance, resulting in enhanced light emitting efficiency and voltage optimization.
Implementation Method 1
an undoped semiconductor layer disposed on the n-type semiconductor layer to fill the roughness and planarize a top surface of the n-type semiconductor layer
Implementation Method 2
an electron blocking layer over the light emitting layer... the electron blocking layer comprises a pattern having height differences so as to have a patterned interface with the p-type semiconductor layer
Implementation Method 3
a light emitting layer over the n-type semiconductor layer... Light emitting diodes (LEDs) are compound semiconductor devices that convert electric energy into light energy
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5
AI summary
Provided are a light emitting diode, a method of fabricating the light emitting diode, a light emitting diode package, and a lighting system. The light emitting diode (100) comprises a first conductive type semiconductor layer (110), a light emitting layer (120) over the first conductive type semiconductor layer, an electron blocking layer (130) over the light emitting layer, and a second conductive type semiconductor layer (140) over the electron blocking layer. The electron blocking layer (130) comprises a pattern (131a,131b) having a height difference.