Transition Stack Light Extraction for LED Voids
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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 between the semiconductor layer and the substrate, featuring a first transition layer with hollow components and a second transition layer that is laterally grown to cover the hollow components, increasing light extraction efficiency by reducing total reflection and absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer layer is formed in conventional LED structure, then the semiconductor stack can be supported, but voids form 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 alternating high-refractive-index and low-refractive-index layers. This extraction eliminates the void formation issue while maintaining structural support function through the layered transition structure.
Solution Approach 2:
The transition stack uses composite material structure with alternating high-refractive-index materials (such as GaN, AlN) and low-refractive-index materials (such as AlGaInP, AlGaAs). This composite approach optimizes both mechanical support and optical transmission properties by combining materials with complementary characteristics.
2Ease of manufacture
If conventional buffer layer structure is used, then manufacturing is simplified, but light extraction efficiency decreases due to total reflection and absorption
Solution Approach 1:
The patent changes the optical parameters by introducing a multi-layer transition structure with varying refractive indices. This parameter change reduces total internal reflection at the interface by creating a gradual refractive index transition, thereby improving light extraction efficiency without significantly complicating the manufacturing process.
Solution Approach 2:
The low-refractive-index layers in the transition stack function similarly to porous materials by creating optical pathways with lower refractive index, reducing total internal reflection and enhancing light extraction. The alternating layer structure creates effective optical porosity that improves light outcoupling.
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 enhances light emitting efficiency by changing the light direction and reducing total reflection, resulting in improved light transmission and extraction efficiency.
Implementation Method 1
increasing light extraction efficiency by reducing total reflection and absorption
Data Source
AI summary
An optoelectronic device comprising, a substrate and a first transition stack formed on the substrate comprising a first transition layer formed on the substrate having a hollow component formed inside the first transition layer, a second transition layer formed on the first transition layer, and a reflector rod formed inside the second transition layer.