LED Electrode Structures for Current Spread and Voltage Reduction
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Solution Overview
Problem
Conventional nitride-based LEDs face limitations in size due to non-uniform current spread and heat-related issues, restricting their luminous efficiency and intensity as the size increases, primarily because of the low conductivity of P-type semiconductor layers and resistance in N-type semiconductor layers.
Innovation Solution
The implementation of improved electrode structures with highly non-uniform distances between P-type and N-type electrode pattern layers, combined with a thin transparent conductive oxide layer, enhances current spreading and reduces operation voltage, allowing for better light extraction and increased luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of LED is increased to enhance luminous efficiency and intensity, then the light-emitting area increases, but the current spread becomes non-uniform and heat-related issues worsen
Solution Approach 1:
The electrode structures are segmented into multiple sub-electrodes arranged in interdigitated patterns. The P-type electrode is divided into multiple P-type sub-electrodes, and the N-type electrode is divided into multiple N-type sub-electrodes. This segmentation allows current to be distributed through multiple pathways, improving current spread uniformity across larger LED areas while preventing localized overheating.
2Area of stationary object
If the P-type semiconductor layer conductivity is low, then the current cannot spread laterally across the layer, but increasing the layer size is needed for higher luminous intensity
Solution Approach 1:
The patent transitions from conventional planar electrode arrangements to three-dimensional vertically stacked interdigitated electrode structures. The P-type and N-type sub-electrodes are positioned at different vertical levels with alternating patterns, creating multiple current pathways that extend laterally across the LED area. This dimensional change enables effective current spreading in larger devices despite the low conductivity of the P-type semiconductor layer.
3Area of stationary object
If heat is generated at certain parts of the LED, then the material around the electrical contact deteriorates quickly, but larger LED size is needed for higher luminous efficiency
Solution Approach 1:
The interdigitated electrode structure segments the current pathways into multiple alternating P-type and N-type sub-electrode regions. This segmentation distributes heat generation across multiple locations rather than concentrating it at single electrical contacts, preventing localized thermal damage and extending component durability in larger LED devices.
4Use of energy by moving object
If conventional electrode structures are used, then the operation voltage remains high, but thinner transparent conductive oxide layer is needed for better light extraction
Solution Approach 1:
The patent changes the geometric parameters of the electrode structures, specifically using thinner transparent conductive oxide layers combined with vertically stacked interdigitated electrode patterns. This parameter change reduces the operation voltage by improving electrical contact efficiency while simultaneously enhancing light extraction by reducing the thickness of the transparent conductive oxide layer that could otherwise absorb or reflect light.
Data Source
Figure 1
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Figure 2A~2B
AI summary
A light-emitting device includes first and second semiconductor layers and a light-emitting layer between the first and second semiconductor layers. The light-emitting device also includes an improved electrode structures.