LED Package Branch Electrodes Current Spreading
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Solution Overview
Problem
Light emitting devices face issues with current crowding and reduced light extraction efficiency due to the concentration of current around electrodes, leading to increased operation voltage and decreased luminous flux.
Innovation Solution
The design includes a light emitting structure with a lower electrode, a light emitting structure comprising a first and second conductive type semiconductor layer, an upper electrode pad, and branch electrodes with a connection electrode that protrudes from the upper electrode pad to improve current spreading and reduce light loss, along with window semiconductor layers and reflection layers to enhance current and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current is concentrated around the electrodes, then electrical connection is improved, but current crowding increases and operation voltage increases
Solution Approach 1:
The upper electrode pad is divided into multiple branch electrodes that extend toward the light emitting structure. This segmentation distributes the current flow across multiple paths, reducing current crowding at any single point while maintaining reliable electrical connection to the light emitting structure.
2Reliability
If electrodes are made larger to reduce resistance, then electrical connection is improved, but light extraction efficiency decreases due to light absorption
Solution Approach 1:
The branch electrodes are positioned to extend toward the light emitting structure but are configured to minimize overlap with light extraction paths. This local optimization allows the electrodes to provide low-resistance electrical connection in areas where it is needed while preserving light extraction efficiency in areas where light needs to exit the device.
3Illumination intensity
If current density is increased to improve luminous intensity, then light output is improved, but droop effect increases and efficiency decreases
Solution Approach 1:
The current path is segmented into multiple branch electrodes that distribute current more uniformly across the light emitting structure. This reduces peak current density while maintaining total luminous output, thereby reducing the droop effect and improving overall efficiency.
4Power
If electrode area is increased to reduce operation voltage, then electrical connection is improved, but light loss due to absorption increases
Solution Approach 1:
The branch electrodes extend in a directional pattern toward the light emitting structure rather than forming a large planar area. This dimensional arrangement allows the electrodes to achieve low resistance through extended path length while minimizing the cross-sectional area that would absorb light, effectively separating the electrical and optical function spaces.
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
This configuration improves current spreading and light extraction efficiency, resulting in enhanced luminous flux and reduced operation voltage, while minimizing light absorption and droop effects.
Implementation Method 1
light emitting devices using the group III-V or II-VI compound semiconductor materials of semiconductors may be p-b junction diodes having characteristics in which electrical energy is converted into light energy
Implementation Method 2
a first reflection layer disposed below the light emitting structure
Data Source
AI summary
A light emitting device of an embodiment comprises: a lower electrode; a light emitting structure disposed on the lower electrode and including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; an upper electrode pad disposed on the light emitting structure; at least one branch electrode connected to the upper electrode pad; and an upper ohmic layer disposed below the at least one branch electrode, wherein the upper electrode pad may include at least one connecting electrode connected to at least one branch electrode, and at least one connecting electrode may be integrally formed with the upper electrode pad and may project at certain intervals from a side surface of the upper electrode pad.