Bridge Electrode Thickness Variation for LED Current Distribution
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Solution Overview
Problem
Current light emitting devices with bridge electrodes are prone to reliability issues due to current concentration on narrow areas, leading to potential burning and deterioration.
Innovation Solution
The design includes a bridge electrode with a greater width and non-uniform thickness, featuring a thicker central section and smaller end sections, disposed between adjacent light emitting cells, with an insulating layer to prevent electrical shorts, and a substrate with roughness to enhance light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bridge electrode has a narrow area, then the device structure is compact, but current concentration occurs leading to reliability deterioration
Solution Approach 1:
The bridge electrode is designed with non-uniform thickness, featuring a thicker central section and thinner end sections. This local quality variation allows the central region to handle higher current density while maintaining overall structural integrity, resolving the contradiction between compact size and reliability by optimizing current distribution across different regions of the electrode.
Solution Approach 2:
The invention transitions from a two-dimensional planar electrode design to a three-dimensional structure with varying thickness. By adding the thickness dimension, the bridge electrode achieves both compact footprint and enhanced current carrying capacity, as the thicker central region provides additional cross-sectional area for current flow without increasing the planar dimensions.
2Reliability
If the bridge electrode width is increased, then current concentration is reduced, but the device area increases
Solution Approach 1:
The bridge electrode implements local quality by having different thicknesses in different regions. The central section is thicker to handle current concentration, while the end sections are thinner. This allows the electrode to function as if it had uniformly large dimensions without actually occupying large device area, resolving the contradiction between reliability and compactness.
Solution Approach 2:
The invention changes the thickness parameter of the bridge electrode from uniform to non-uniform distribution. By varying the thickness parameter across the electrode structure, the design achieves enhanced current carrying capacity in critical regions while maintaining overall compact dimensions, thus resolving the contradiction between reliability improvement and area increase.
Data Source
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AI summary
Disclosed is a light emitting device comprising a plurality of light emitting cells, and a bridge electrode electrically connecting two adjacent light emitting cells, and the plurality of light emitting cells comprise a light emitting structure including a first conductive semiconductor layer, a second conductive semiconductor layer and an active layer between the first conductive semiconductor layer and the second conductive semiconductor layer, a first electrode on the first conductive semiconductor layer and a second electrode on the second conductive semiconductor layer, wherein the bridge electrode has a part thicker than the first electrode and the second electrode.