Semiconductor Light-Emitting Device Electrode Design
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Solution Overview
Problem
Semiconductor light-emitting devices face low light extraction efficiency due to absorption by n-side electrodes and mount materials, and constraints on electrode design limit the enlargement of reflection films.
Innovation Solution
A semiconductor light-emitting device with a laminated structure featuring a dielectric film with alternating refractive indices and metal films with high reflectance and contact resistance, optimizing the electrode design to enhance light reflection and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the area of the n-side electrode is enlarged to reduce contact resistance and enable wire bonding, then the electrode design constraints are satisfied, but the light extraction efficiency is reduced due to increased absorption
Solution Approach 1:
The n-side electrode is designed with spatially varying properties: a first region with low contact resistance for electrical connection and a second region with high reflectance for light extraction. This local differentiation allows the electrode to simultaneously satisfy electrical reliability requirements and optical performance requirements without compromise.
Solution Approach 2:
The n-side electrode is segmented into functionally distinct regions: a first region optimized for electrical contact (low resistance) and a second region optimized for optical reflection (high reflectance). This segmentation enables independent optimization of electrical and optical functions within the same electrode structure.
2Loss of energy
If the reflection film area is enlarged to improve light extraction, then the light extraction efficiency increases, but the electrode design constraints cannot be satisfied
Solution Approach 1:
Different regions of the electrode are assigned different optical properties: the first region has lower reflectance to maintain electrical functionality, while the second region has high reflectance to enhance light extraction. This local quality differentiation allows the electrode to fulfill both electrical and optical design requirements simultaneously.
3Ease of manufacture
If a single metal film is used for the electrode, then the manufacturing process is simple, but both high reflectance and low contact resistance cannot be achieved simultaneously
Solution Approach 1:
The n-side electrode employs a composite structure with two distinct metal films: a first metal film providing low contact resistance for electrical connection, and a second metal film providing high reflectance for light extraction. This composite material approach enables simultaneous achievement of electrical and optical performance targets that cannot be realized with a single material.
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
Improves light extraction efficiency by reflecting emitted light efficiently and reducing absorption, while maintaining necessary electrode areas for contact and bonding.
Implementation Method 1
a second region including a second metal film provided on the part of the first semiconductor layer, the second region having a higher reflectance for light emitted from the light-emitting layer
Implementation Method 2
a dielectric laminated film provided on the first semiconductor layer and the second semiconductor layer being not covered with any one of the first electrode and the second electrode on the first main surface, the dielectric laminated film having a plurality of dielectric films having different refractive indices being laminated
Data Source
AI summary
A semiconductor light-emitting device includes: a laminated structure, a first electrode, a second electrode and a dielectric laminated film. The laminated structure includes, a first semiconductor layer, a second semiconductor layer, and a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer, in which the second semiconductor layer and the light-emitting layer are selectively removed and a part of the first semiconductor layer is exposed to a first main surface on the side of the second semiconductor layer. The first electrode is provided on the first main surface of the laminated structure and connected to the first semiconductor layer and has a first region including a first metal film provided on the first semiconductor layer of the first main surface, and a second region including a second metal film provided on the first semiconductor layer and having a higher reflectance for light emitted from the light-emitting layer than the first metal film and having a higher contact resistance with respect to the first semiconductor layer than the first metal film. The second electrode is provided on the first main surface of the laminated structure and connected to the second semiconductor layer. The dielectric laminated film is provided on the first and second semiconductor layer being not covered with the first and second electrode and has a plurality of dielectric films having different refractive indices being laminated.