Textured LED Substrate Structure for Higher Light Extraction
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in maximizing light extraction efficiency due to total internal reflection and substrate material limitations, which restrict the emission of light from the active layer.
Innovation Solution
A light-emitting device with a textured substrate featuring micro-structures and an inclined surface is developed, incorporating a dislocation stop layer of AlGaN, which reduces total internal reflection and enhances light extraction efficiency by forming micro-protrusions and micro-spaces on the substrate, allowing for improved light emission through the bottom surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional flat substrate is used, then the device structure is simple, but light extraction efficiency is low due to total internal reflection
Solution Approach 1:
The substrate surface is textured with micro-structures (protrusions and recesses) that create curved surfaces. This curvature disrupts the flat interface between substrate and semiconductor layers, reducing total internal reflection and improving light extraction efficiency without significantly complicating the manufacturing process
Solution Approach 2:
The substrate is designed with a porous or textured structure containing micro-protrusions and micro-recesses. This porous-like topology increases the effective surface area and creates multiple light extraction paths, reducing internal reflection and enhancing light outcoupling efficiency
2Loss of energy
If a textured substrate with micro-structures is used, then light extraction efficiency is enhanced, but the device structure becomes more complex
Solution Approach 1:
The micro-texturing creates curved surfaces that are effective at reducing total internal reflection. These curved features can be integrated into the substrate manufacturing process without requiring additional complex assembly steps, balancing performance improvement with manufacturing simplicity
Solution Approach 2:
The textured structure is integrated as part of the substrate itself rather than as a separate component. The micro-protrusions and micro-recesses are formed during substrate fabrication, merging the light extraction function into the substrate structure and avoiding additional device complexity
3Loss of energy
If dislocation stop layer is added, then light extraction efficiency is improved, but manufacturing process becomes more complex
Solution Approach 1:
The dislocation stop layer is incorporated into the semiconductor layer structure during the epitaxial growth process, before device operation. This preliminary incorporation of the light extraction enhancement feature allows it to function without requiring additional manufacturing steps or post-processing 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 textured substrate design significantly enhances light extraction efficiency by reducing total internal reflection and optimizing light emission, leading to increased output and improved performance of the light-emitting device.
Implementation Method 1
reduces total internal reflection and enhances light extraction efficiency by forming micro-protrusions and micro-spaces on the substrate
Data Source
AI summary
A light-emitting device includes: a substrate having a top surface, wherein the top surface comprises a first portion and a second portion; a first semiconductor stack on the first portion, comprising a first upper surface and a first side wall; and a second semiconductor stack on the first upper surface, comprising a second upper surface and a second side wall, and wherein the second side wall connects the first upper surface; wherein the first semiconductor stack comprises a dislocation stop layer; wherein the dislocation stop layer comprises AlGaN; and wherein the first side wall and the second portion of the top surface form an acute angle α between thereof.