Transparent Electrode Hole and Junction Layer for LED Bonding
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Solution Overview
Problem
The existing semiconductor light-emitting devices using GaN-based compound semiconductors face issues with low electrode strength and light extraction efficiency due to the peeling off of bonding pad electrodes made of reflection films like Ag or Al, leading to poor yield in manufacturing lamps.
Innovation Solution
A semiconductor light-emitting device with a transparent electrode having a hole portion and a junction layer, where the bonding pad electrode covers the junction layer, and is made of materials like Au, Al, or their alloys, with a junction layer of elements like Al, Ti, or Cr, enhancing junction strength and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bonding pad electrode made of reflection film (Ag, Al) is provided on a transparent electrode (ITO), then the electrode strength is improved, but the bonding pad electrode peels off from the transparent electrode during bonding wire process
Solution Approach 1:
The patent applies composite materials by creating a multi-layer electrode structure consisting of a transparent electrode (ITO), a reflection film (Ag or Al), and a resin layer. This composite structure allows the bonding pad electrode to maintain both strength and adhesion, preventing peeling during the bonding wire process while preserving electrical and optical functions.
2Strength
If a bonding pad electrode is provided on a transparent electrode to improve strength, then electrode strength is improved, but light extraction efficiency deteriorates due to shielding
Solution Approach 1:
The patent segments the electrode structure by separating the bonding pad electrode into two functional layers: a reflection film for electrical conductivity and a transparent resin layer for mechanical strength. This segmentation allows light to pass through the resin layer while the reflection film maintains electrical function, thus preserving light extraction efficiency while providing electrode strength.
Solution Approach 2:
The patent applies local quality by making the resin layer transparent in the light extraction region, allowing light to pass through without shielding. The reflection film is positioned specifically to provide electrical conductivity and bonding function only where needed, rather than covering the entire electrode area, thus maintaining light extraction efficiency while providing necessary structural support.
3Device complexity
If only a p-type electrode made of metal is laminated on the p-type GaN-based compound semiconductor layer, then the electrode structure is simple, but current diffusion in the in-plane direction is almost non-existent
Solution Approach 1:
The transparent electrode (ITO) serves multiple functions: it provides electrical conductivity for current injection, acts as a transparent window for light extraction, and serves as a base layer for the bonding pad electrode structure. This multi-functionality allows a single layer to address both electrical and optical requirements, while the added resin layer specifically addresses current diffusion without significantly increasing overall structural complexity.
Data Source
AI summary
A semiconductor light-emitting device (1) of the present invention includes: a substrate (101); a laminated semiconductor layer (20) containing a light-emitting layer, which is formed on the substrate (101); a first electrode (111) formed on the upper surface (106c) of the laminated semiconductor layer (20); and a second electrode (108) formed on an exposed surface (104c) that is formed by partially cutting the laminated semiconductor layer (20), wherein the first electrode (111) includes a transparent electrode (109) containing a hole portion (109a) through which the upper surface (106c) of the laminated semiconductor layer (20) is exposed, a junction layer (110) formed on a bottom surface (109b) and an inner wall (109d) of the hole portion (109a), and a bonding pad electrode (120) formed to cover the junction layer (110).