LED Current Blocking Layer for Light Extraction and Spreading
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Solution Overview
Problem
Light emitting diodes (LEDs) face issues with current crowding and light loss due to absorption at the contact region between the connection pad and the nitride semiconductor stack, leading to reduced luminous efficacy and reliability.
Innovation Solution
Incorporating a current blocking layer with high reflectance between the connection pad and the nitride semiconductor stack, and designing curved regions in the connection pads and current blocking layers to improve current spreading and light extraction efficiency, while minimizing contact area to prevent excessive forward voltage increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a connection pad is directly contacted to the first conductivity type semiconductor layer, then electrical connection is achieved, but current crowding occurs and light is absorbed causing reduced luminous efficacy
Solution Approach 1:
A current blocking layer is introduced as an intermediary between the connection pad and the first conductivity type semiconductor layer. This layer serves dual functions: it blocks excess current to prevent current crowding and reflects light to prevent absorption by the connection pad, thereby resolving both the electrical connection reliability and light absorption loss issues
Solution Approach 2:
The curvature radius of the connection pad is optimized to balance current spreading and light extraction. By adjusting the geometric parameter (curvature radius) of the connection pad, the patent achieves improved current dispersion while maintaining effective light extraction, preventing both current crowding and excessive light absorption
2Reliability
If the contact area between connection pad and semiconductor layer is increased to improve current spreading, then current dispersion improves, but forward voltage increases
Solution Approach 1:
The curvature radius of the connection pad is optimized to balance current spreading and light extraction. By adjusting the geometric parameter (curvature radius) of the connection pad, the patent achieves improved current dispersion while maintaining effective light extraction, preventing both current crowding and excessive light absorption
Solution Approach 2:
The current blocking layer is positioned specifically in the contact region between the connection pad and semiconductor layer, providing localized current blocking where needed most. This localized approach improves current dispersion capability without requiring a large increase in overall contact area, thereby avoiding excessive forward voltage increase
3Reliability
If current blocking layer is added to prevent current crowding, then current dispersion improves, but device complexity increases
Solution Approach 1:
The current blocking layer serves multiple functions simultaneously: it blocks excess current to prevent current crowding, reflects light to prevent absorption by the connection pad, and can be integrated with existing semiconductor layer structures. This multi-functionality improves current dispersion capability without proportionally increasing device complexity
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 solution enhances current spreading, reduces current crowding, and improves light output and reliability by minimizing light absorption, thereby increasing the luminous efficacy of the LED without increasing forward voltage.
Implementation Method 1
a first current blocking layer interposed between the first conductivity type semiconductor layer and the first connection pad
Implementation Method 2
the first connection pad includes a first curved region having a radius of curvature of R1; the first current blocking layer includes a second curved region having a radius of curvature of R2
Implementation Method 3
A light emitting diode (LED) refers to a semiconductor device that generates a small number of carriers (electrons or holes) injected through a p-n junction structure thereof and emits light through recombination of the carriers
Data Source
AI summary
A light emitting diode includes a current blocking layer interposed between a first connection pad and a first conductivity type semiconductor layer to improve efficiency in spreading of electric current supplied to the first conductivity type semiconductor layer.