GaN LED Electrode Segmentation for Current Spreading
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Solution Overview
Problem
Current light emitting devices using Group III-V nitride semiconductors face challenges in improving reliability and efficiency due to limitations in electrode structures, which affect current spreading and light extraction.
Innovation Solution
A light emitting device with a stacked structure comprising a current spreading layer, an insulation layer, and electrodes on a second conductive type semiconductor layer, where the electrodes' patterns overlap vertically to enhance current distribution and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electrode structure is used on the second conductive type semiconductor layer, then the device structure is simple, but current spreading is insufficient and reliability is reduced
Solution Approach 1:
The electrode structure is segmented into multiple functional layers: a first electrode layer, a second electrode layer, and a bridge electrode layer connecting them. This segmentation allows each layer to perform specific functions (current injection, current spreading, electrical connection) thereby improving overall device reliability through optimized current distribution while maintaining manufacturing feasibility
Solution Approach 2:
The patent implements a nested electrode configuration where the first electrode layer is positioned at the bottom, the second electrode layer is positioned at the top, and the bridge electrode layer connects them laterally. This nested arrangement enables efficient current spreading from the first electrode through the semiconductor layer to the second electrode, improving reliability without excessive complexity
2Reliability
If electrodes are positioned without vertical overlap, then the manufacturing process is simpler, but light extraction efficiency is reduced
Solution Approach 1:
The patent utilizes vertical stacking of electrode patterns in the z-dimension, where the first electrode layer and second electrode layer are positioned at different heights with their patterns vertically overlapping when viewed from the top. This dimensional arrangement improves light extraction efficiency by creating optical pathways while maintaining manageable manufacturing complexity through standard layer-by-layer fabrication processes
3Productivity
If current spreading layer and insulation layer are not stacked, then the manufacturing process is simpler, but current distribution and light extraction are insufficient
Solution Approach 1:
The device structure is segmented into distinct functional layers including a current spreading layer and an insulation layer stacked on the second conductive type semiconductor layer. This segmentation enables the current spreading layer to optimize electrical current distribution while the insulation layer provides electrical isolation, thereby improving light extraction efficiency and external quantum efficiency without excessive manufacturing complexity
Solution Approach 2:
The stacked structure of current spreading layer and insulation layer serves multiple functions simultaneously: electrical current spreading, electrical insulation, and optical management. This multi-functional design improves productivity in terms of light extraction efficiency while maintaining reasonable manufacturing complexity through integrated layer fabrication
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 proposed structure improves the reliability and efficiency of light emitting devices by effectively spreading current and reducing light absorption, leading to enhanced external quantum efficiency and light extraction.
Implementation Method 1
a current spreading layer on the second conductive type semiconductor layer
Implementation Method 2
an insulation layer on the first electrode
Implementation Method 3
a light emitting structure layer including a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer
Data Source
AI summary
Provided is a light emitting device. The light emitting device includes a light emitting structure layer comprising a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer. A first electrode is connected to the first conductive type semiconductor layer and includes first pad, plurality of first bridge portions and plurality of first contact portions. A current spreading layer is on a top surface of the second conductive type semiconductor layer. An insulation layer is on an upper surface of the first conductive type semiconductor layer and a top surface of the current spreading layer. A second electrode is on a top surface of the current spreading layer. The plurality of first bridge portions are extended from the first pad at an acute angle to each other.