LED Light Extraction via Hexagonal-Pyramid Cavities and Bonding Layers
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Solution Overview
Problem
Conventional semiconductor light-emitting diode (LED) devices suffer from low light-emitting efficiency due to light absorption by metal electrodes and reliability issues caused by poor adhesion between reflective metal layers and semiconductor layers.
Innovation Solution
A high-efficiency light-emitting device structure featuring a substrate with a reflective layer, bonding layer, semiconductor layers with distinct lower and higher regions, and electrical structures including current blocking and spreading layers, along with hexagonal-pyramid cavities to enhance light extraction, addresses the adhesion and absorption issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective metal layer is formed between the electrode and light-emitting stacked layer to improve light-emitting efficiency, then light absorption is reduced, but adhesion between the reflective metal layer and semiconductor layer deteriorates
Solution Approach 1:
A bonding layer is introduced as an intermediary between the reflective metal layer and the light-emitting stacked layer. This bonding layer serves as a mediator that provides both optical reflectivity and mechanical adhesion, resolving the contradiction between reducing light absorption and maintaining reliable bonding.
Solution Approach 2:
The reflective layer is designed as a composite structure comprising multiple layers including a bonding layer and a reflective metal layer. This composite material approach allows the structure to simultaneously achieve both functions: the bonding layer provides adhesion while the reflective metal layer reduces light absorption.
2Productivity
If a reflective metal layer with high reflectivity is used, then light-emitting efficiency is improved, but adhesion with the semiconductor layer deteriorates
Solution Approach 1:
The bonding layer acts as an intermediary that decouples the conflicting requirements of high reflectivity and strong adhesion. It allows the reflective metal layer to maintain high reflectivity for improved light-emitting efficiency while the bonding layer itself provides the necessary adhesion to the semiconductor layer.
Solution Approach 2:
The reflective layer is segmented into distinct functional layers: a bonding layer for adhesion and a reflective metal layer for optical performance. This segmentation allows each layer to optimize its specific function without compromising the other, thereby achieving both high light-emitting efficiency and reliable adhesion.
3Loss of energy
If metal electrodes are used in conventional LED devices, then electrical conductivity is achieved, but light absorption increases reducing light-emitting efficiency
Solution Approach 1:
The bonding layer serves as an intermediary between the metal electrode and the light-emitting stacked layer, allowing the metal to provide electrical conductivity while the bonding layer and reflective structure minimize light absorption, thereby improving light-emitting efficiency.
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 proposed structure significantly improves light-emitting efficiency by reducing total reflection and enhancing light extraction, while maintaining reliability through improved adhesion and current management.
Implementation Method 1
a reflective layer formed on the substrate
Implementation Method 2
for increasing the light extraction efficiency
Data Source
AI summary
This invention provides a high-efficiency light-emitting device and the manufacturing method thereof. The high-efficiency light-emitting device includes a substrate; a reflective layer; a bonding layer; a first semiconductor layer; an active layer; and a second semiconductor layer formed on the active layer. The second semiconductor layer includes a first surface having a first lower region and a first higher region.