Flip-Chip LED Ring Electrode Layout for Even Current Injection
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Solution Overview
Problem
Current flip-chip light-emitting devices face limitations in size due to uneven current spreading, which reduces light emission efficiency as the epitaxial layer is not effectively utilized as a current spreading layer, leading to concentrated light emission near electrodes.
Innovation Solution
A flip-chip light-emitting device design featuring a transparent substrate with an epitaxial structure, a transparent dielectric layer, and strategically arranged contact electrodes, including a metallic reflection layer and insulating layers, to improve current distribution and reduce light emission loss, with contact electrodes arranged in an array manner and distributed along concentric circular rings to enhance even current spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the conventional flip-chip light-emitting device is driven by a larger current, then the light emission area increases, but the current spreading becomes uneven and concentrates near electrodes, lowering light emission efficiency
Solution Approach 1:
The device is divided into multiple independently controllable LED chips arranged in an array, with each chip having its own contact electrodes. This segmentation allows current to be distributed across multiple chips rather than concentrating near a single electrode, enabling larger total current while maintaining uniform current spreading and high light emission efficiency across the entire device area.
Solution Approach 2:
The patent transitions from a conventional planar electrode arrangement to a three-dimensional structure where contact electrodes are positioned at different heights and locations. The first contact electrodes are embedded in the transparent dielectric layer while second contact electrodes are on the upper surface, creating a multi-level current distribution system that improves current spreading uniformity across the epitaxial structure.
2Area of stationary object
If the size of the flip-chip light-emitting device is increased, then the light emission area increases, but the epitaxial layer cannot be effectively utilized as a current spreading layer, reducing light emission efficiency
Solution Approach 1:
The large-area device is segmented into multiple LED chips, each with its own contact electrode structure. This allows the epitaxial layer to serve as an effective current spreading layer for each individual chip while maintaining overall large device area, as current distributes uniformly across the epitaxial structure of each chip rather than having to spread across the entire large device area from a single electrode.
Solution Approach 2:
Each LED chip region has locally optimized contact electrode configuration with first contact electrodes embedded in the transparent dielectric layer and second contact electrodes on the upper surface. This local optimization ensures effective current spreading through the epitaxial layer in each region, while the overall device maintains large area through the array arrangement of multiple chips.
3Stability of the object's composition
If contact electrodes are arranged in an array manner with second contact electrodes distributed along concentric circular rings, then current spreading uniformity improves, but device structure complexity increases
Solution Approach 1:
The complex electrode arrangement is segmented and standardized for each LED chip in the array. Each chip has a replicated pattern of first contact electrodes embedded in the transparent dielectric layer and second contact electrodes on the upper surface distributed along concentric circular rings. This modular segmentation makes the complex structure manufacturable through repeated patterns rather than requiring unique complex designs for the entire large-area device.
Solution Approach 2:
The same electrode arrangement pattern serves multiple functions: the first contact electrodes provide current injection, the second contact electrodes provide current extraction and electrical connection, and the concentric circular ring distribution ensures uniform current spreading across the epitaxial layer. This universal pattern is replicated across all LED chips in the array, simplifying manufacturing while achieving current spreading uniformity.
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 design improves light emission efficiency by reducing the contact area between electrodes and the semiconductor layers, allowing for more uniform current distribution and increased light emission, particularly in larger devices.
Implementation Method 1
a metallic reflection layer, a first insulating layer, and an electrode pad region. The metallic reflection layer is formed on the transparent dielectric layer
Implementation Method 2
a transparent substrate, an epitaxial structure, a transparent dielectric layer
Data Source
AI summary
A flip-chip light-emitting device includes a transparent substrate, an epitaxial structure, a transparent dielectric layer, a plurality of first contact electrodes, multiple second contact electrodes, a metallic reflection layer, a first insulating layer, and an electrode pad region. The epitaxial structure is formed on the transparent substrate, and includes a first type semiconductor layer, an active layer, and a second type semiconductor layer. The first and second contact electrodes are embedded in the transparent dielectric layer, and respectively connected to the first and second type semiconductor layers. The second and first contact electrodes are arranged in an array. The second contact electrodes are disposed in a region perpendicularly below the first pad and are distributed along a circular ring that is concentric with one of the first contact electrodes. A light emitting module includes a circuit board, and the flip-chip light emitting device is mounted on the circuit board.