Transition Stack with Hollow Components for LED Light Extraction
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) suffer from reduced light transmission and extraction efficiency due to voids in the buffer layer, resulting in a gray surface and decreased light emission.
Innovation Solution
An optoelectronic device with a transition stack formed on a substrate, featuring a first transition layer with hollow components and a second transition layer, which is either unintentionally doped or undoped, enhancing light extraction efficiency by reducing total reflection and increasing porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a buffer layer is formed in the semiconductor stack, then the structural stability is improved, but voids are generated inside the buffer layer causing gray surface and reduced light transmission
Solution Approach 1:
The patent removes the problematic buffer layer entirely and replaces it with a transition stack consisting of multiple transition layers with different refractive indices. This extraction of the harmful buffer layer eliminates the void formation issue while maintaining the necessary structural transition between substrate and semiconductor layers through the alternative transition stack structure.
Solution Approach 2:
The transition stack is composed of multiple layers with different refractive indices (first transition layer, second transition layer, third transition layer) forming a composite structure. This composite approach allows optimization of both structural stability and light transmission by carefully selecting materials with progressively matching refractive indices, preventing void formation while enhancing light extraction efficiency.
2Illumination intensity
If the buffer layer is made denser to reduce voids, then the light transmission is improved, but the manufacturing complexity increases
Solution Approach 1:
Rather than attempting to densify the buffer layer to reduce voids, the patent extracts the buffer layer concept entirely and replaces it with a transition stack of multiple thin layers. Each layer is designed with specific refractive index characteristics, eliminating the need for complex densification processes while achieving superior light transmission through refractive index matching.
Solution Approach 2:
The patent changes the key parameter from buffer layer density to refractive index gradient across multiple transition layers. By controlling the refractive index of each transition layer (first, second, and third layers with progressively different indices), the design achieves optimal light transmission without requiring complex manufacturing processes to control density, simplifying the overall manufacturing approach.
3Ease of manufacture
If conventional LED structure is used, then the manufacturing process is simple, but the light extraction efficiency is reduced due to total reflection
Solution Approach 1:
The transition stack employs a composite structure of multiple layers with different refractive indices positioned between the substrate and the light-emitting semiconductor layers. This composite design enables gradual refractive index matching, reducing total internal reflection and improving light extraction efficiency while maintaining manufacturing simplicity through standard semiconductor fabrication techniques.
Solution Approach 2:
The patent introduces refractive index as a key controllable parameter across the transition layers. By designing the first, second, and third transition layers with progressively different refractive indices, the system optimizes light extraction efficiency through refractive index matching, achieving better light extraction without significantly complicating the manufacturing process.
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 structure increases light emitting efficiency by changing the direction of photons and reducing absorption, resulting in improved light transmission and extraction efficiency.
Implementation Method 1
The structure increases light emitting efficiency by changing the direction of photons
Implementation Method 2
enhancing light extraction efficiency by reducing total reflection
Data Source
AI summary
An optoelectronic device includes a substrate and a first transition stack formed on the substrate including at least a first transition layer formed on the substrate and having at least one hollow component formed inside the first transition layer, and a second transition layer wherein the second transition layer is an unintentional doped layer or an undoped layer formed on the first transition layer.