LED Current Spreading via Segmented P-layer and Contact Holes
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Solution Overview
Problem
GaN-based LEDs suffer from reduced luminous efficiency due to non-uniform current distribution, with current concentrating at the edges rather than being spread across the light-emitting area, particularly in larger LEDs.
Innovation Solution
The design incorporates multiple contact holes and connection patterns on the N-type semiconductor layer, with insulating layers and contact layers to distribute current uniformly, and the use of light-emitting cells with separate contact regions to decentralize current concentration, enhancing current spreading performance and increasing the light-emitting area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current flows through the P-type semiconductor layer to the N-type semiconductor layer, then electrical connection is achieved, but current concentrates at the edges reducing luminous efficiency
Solution Approach 1:
The P-type semiconductor layer is segmented into multiple regions with different specific resistivities. A first P-type semiconductor layer with higher specific resistivity is positioned adjacent to the P-electrode, while a second P-type semiconductor layer with lower specific resistivity is positioned away from the P-electrode. This segmentation creates multiple current flow paths that distribute current more uniformly across the LED structure, reducing edge concentration and improving luminous efficiency.
2Reliability
If the P-type semiconductor layer has high specific resistivity, then electrical isolation is improved, but current distribution becomes non-uniform
Solution Approach 1:
Different regions of the P-type semiconductor layer are assigned different specific resistivity values according to their functional requirements. The region adjacent to the P-electrode uses higher specific resistivity material for electrical isolation, while regions away from the electrode use lower specific resistivity material for current distribution. This local quality variation allows each region to optimize its performance for its specific function.
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 approach improves luminous efficiency by uniformly spreading current across the LED, reducing concentration at edges and increasing the light-emitting region, thereby enhancing the performance of large-sized LEDs.
Implementation Method 1
A connection pattern is formed in the contact holes and on the P-contact layer. The connection pattern electrically connects the exposed portions of the N-type semiconductor layer in the contact holes to one another.
Implementation Method 2
An insulating layer is interposed between the P-contact layer and the connection pattern and between sidewalls of the contact holes and the connection pattern.
Implementation Method 3
N-contact layers may be interposed between the connection pattern and the exposed portions of the N-type semiconductor layer in the contact holes. The N-contact layers may be in ohmic-contact with the N-type semiconductor layer to thereby lower contact resistance.
Implementation Method 4
GaN-based light emitting diodes (LEDs) have considerably changed LED technologies and are currently used in a variety of applications
Data Source
AI summary
Disclosed is a light emitting diode (LED) for enhancing the current spreading performance. The LED includes a plurality of contact holes exposing an N-type semiconductor layer through a P-type semiconductor layer and an active layer, and a connection pattern electrically connecting exposed portions of the N-type semiconductor layer through the contact holes, thereby enhancing current spreading in the N-type semiconductor layer. In addition, disclosed is an LED including a plurality of light emitting cells spaced apart from one another on an N-type semiconductor layer and an N-contact layer between the light emitting cells. A plurality of light emitting cells are employed in the LED, so that current can be spread in the LED.