Vertical LED Current Blocking Layer Design
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Solution Overview
Problem
In vertical LED structures, current concentration occurs at the bottom of the first electrode layer, leading to increased operating voltage, reduced lifespan, and deteriorated reliability, as well as inefficient light output due to absorption by the electrode layer.
Innovation Solution
Incorporating a current blocking layer on the second electrode layer, which forms a schottky contact with the second conductive type semiconductor layer, and strategically positioning it to overlap with the first electrode layer, thereby altering the current flow path and reducing concentration, and forming current blocking layers on both central and peripheral portions of the second electrode layer to spread current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a vertical LED structure is used with overlapped electrode layers, then the device structure is compact and manufacturing is simplified, but current concentration occurs at the bottom of the first electrode layer leading to increased operating voltage and reduced reliability
Solution Approach 1:
A current blocking layer is introduced as an intermediary component between the second electrode layer and the second conductive type semiconductor layer. This current blocking layer selectively blocks current flow in specific regions, preventing current concentration at the bottom of the first electrode layer while maintaining the compact vertical structure. The current blocking layer acts as a mediator that redistributes current flow through the device, improving reliability without increasing structural complexity.
2Ease of manufacture
If a vertical LED structure with overlapped electrode layers is used, then manufacturing is simplified, but light generated from the active layer is reflected and absorbed by the first electrode layer, deteriorating optical efficiency
Solution Approach 1:
The current blocking layer serves as an intermediary that not only controls current flow but also prevents light absorption by the electrode layers. By positioning the current blocking layer between the active layer and the electrode layers, it acts as a barrier that reduces light reflection and absorption, thereby improving optical efficiency while maintaining the simplified manufacturing process of the vertical structure.
3Reliability
If current blocking layers are added to prevent current concentration, then operating voltage is stabilized and reliability is improved, but device structure becomes more complex
Solution Approach 1:
The current blocking layer is designed to perform multiple functions simultaneously: it blocks current in specific regions to prevent concentration, and it also serves as a structural element that maintains the vertical alignment of the device. By making the current blocking layer multi-functional, the patent achieves improved stability and reliability without proportionally increasing structural complexity, as the same layer provides both electrical and structural benefits.
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 stabilizes the operation voltage, enhances light intensity, and improves optical efficiency by preventing current concentration and minimizing light absorption by the electrode layer.
Implementation Method 1
a current blocking layer on the projection part of the second electrode layer... forms a schottky contact with the second conductive type semiconductor layer
Data Source
AI summary
A light emitting device according to an embodiment includes a second electrode layer comprising at least one projection part; at least one current blocking layer on the projection part of the second electrode layer; a second conductive type semiconductor layer on the second electrode layer and the current blocking layer; an active layer on the second conductive type semiconductor layer; a first conductive type semiconductor layer on the active layer; and a first electrode layer on the first conductive type semiconductor layer, at least a portion of the first electrode layer corresponding with the current blocking layer in a vertical direction.