LED Electrode Segmentation for Uniform Current Distribution
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face issues with non-uniform current spreading and reduced brightness due to electrode structures that shelter light and concentrate current near semiconductor layers, leading to inefficient light emission and higher operating voltages.
Innovation Solution
The proposed light-emitting device features a substrate with specific edge configurations and semiconductor stacks, including a transparent conductive layer and unique electrode designs with finger electrodes and current blocking regions to distribute current uniformly and enhance light extraction, preventing current crowding and optimizing brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional electrode structures are used, then the LED structure is simple, but current crowds near the electrodes and light emission is blocked
Solution Approach 1:
The electrode structure is divided into multiple segments including a first electrode extending from one short edge, a second electrode extending from the opposite short edge, and a third electrode extending along the long edge. This segmentation distributes current injection points across multiple locations, preventing current crowding and improving current spreading uniformity throughout the semiconductor layer.
Solution Approach 2:
The electrode configuration transitions from conventional point or line contacts to a distributed three-dimensional arrangement. The first and second electrodes extend along one dimension (from short edges), while the third electrode extends along the perpendicular dimension (long edge), creating a comprehensive current distribution network that addresses both spatial dimensions of current flow.
2Illumination intensity
If electrodes are placed close to semiconductor layers for simple structure, then current spreads poorly, but increasing electrode distance improves current distribution
Solution Approach 1:
Different regions of the semiconductor layer are provided with different current injection characteristics through the strategically positioned electrodes. The first and second electrodes provide current injection at opposite corners, while the third electrode provides additional current injection along the long edge, creating localized current distribution patterns that collectively achieve uniform overall distribution and reduce operating voltage.
3Stability of the object's composition
If conventional parallel finger electrodes are used, then manufacturing is simple, but current distribution uniformity is poor
Solution Approach 1:
The electrode configuration employs asymmetric positioning and orientation. The first electrode extends from one short edge, the second electrode from the opposite short edge, and the third electrode extends along the long edge. This asymmetric arrangement creates non-uniform current injection patterns that collectively achieve uniform current distribution across the semiconductor layer, overcoming the limitations of symmetric parallel finger electrode designs.
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 design achieves improved brightness and reduced forward voltage by ensuring uniform current distribution and efficient light extraction, leading to increased optical output power and extended LED lifespan.
Implementation Method 1
holes from the p-type semiconductor layer and electrons from the n-type semiconductor layer are combined in the active layer to release light
Data Source
AI summary
A light-emitting device includes: a substrate, including a first edge, a second edge, a third edge and a fourth edge; a semiconductor stack formed on the substrate, comprising a first semiconductor layer, a second semiconductor layer and an active layer; a first electrode formed on the first semiconductor layer, comprising a first pad electrode; and a second electrode formed on the second semiconductor layer, comprising a second pad electrode and a second finger electrode; wherein in a top view, the first pad electrode is adjacent to a corner of the substrate that is intersected by the first and the second edges; the second finger electrode is not parallel with the third and the first edges; and a distance between the second finger electrode and the first edge increases along a direction from an end of the second finger electrode that connects the second pad electrode toward the second edge.