LED Electrode Structure for Reducing Current Crowding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gallium nitride light-emitting diodes (LEDs) face issues with current crowding and low carrier mobility, leading to reduced light-emitting efficiency and reliability due to the current crowding effect at the bottom of the p-type electrode pad.
Innovation Solution
A light-emitting diode structure is developed with a protective layer and insulation layer formed below the extension portion of the electrode, including a transparent conductive layer with holes to expose the conductive layer and improve current spreading, and a second electrode with vias to enhance light extraction efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LED structure with p-type electrode pad is used, then the manufacturing process is simple, but current crowding occurs at the bottom of the pad leading to reduced light-emitting efficiency and reliability
Solution Approach 1:
The electrode structure is segmented into multiple functional layers: the reflective electrode layer (241) is divided into a pad portion (243) and an extension portion (244), with the extension portion extending along the light-emitting layer (212) to distribute current more evenly. Additionally, a transparent conductive layer (230) is introduced as a separate functional layer to further assist current spreading, thereby reducing current crowding and improving reliability without significantly complicating the overall structure.
Solution Approach 2:
A transparent conductive layer (230) is introduced as an intermediary between the reflective electrode layer (241) and the light-emitting layer (212). This intermediate layer serves as a mediator to distribute current more uniformly across the light-emitting area, preventing current crowding at the electrode-pad interface while maintaining the simplicity of the original electrode structure.
2Productivity
If the electrode extension portion is added to improve current spreading, then light-emitting efficiency improves, but the manufacturing process becomes more complex
Solution Approach 1:
The extension portion (244) of the reflective electrode layer (241) is merged with the transparent conductive layer (230) in certain regions, creating a combined structure that simultaneously provides current spreading and light extraction functions. This merging reduces the need for separate complex structures while achieving improved light-emitting efficiency through enhanced current distribution.
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 effectively enhances light-emitting efficiency and reliability by reducing current crowding and improving current spreading, resulting in superior reflection efficiency and reduced light absorption, thereby improving the overall performance of the LED.
Implementation Method 1
The transparent conductive layer is disposed on the first semiconductor layer and covers the insulation layer
Implementation Method 2
The protective layer is disposed on the transparent conductive layer, and has a plurality of first holes formed above and along the extension area of the first electrode region to permit the transparent conductive layer to be exposed
Implementation Method 3
The first electrode is disposed on the protective layer, and includes a pad portion and an extension portion. The extension portion fills the first holes so as to electrically connect the transparent conductive layer
Implementation Method 4
The light-emitting epitaxial layered unit includes a first semiconductor layer, a second semiconductor layer, and a light-emitting layer sandwiched between the first and second semiconductor layers
Data Source
AI summary
Disclosed is a light-emitting diode which includes a light-emitting epitaxial layered unit, an insulation layer, a transparent conductive layer, a protective layer, a first electrode, and a second electrode. The light-emitting epitaxial layered unit includes a first semiconductor layer, a second semiconductor layer, and a light-emitting layer sandwiched between the first and second semiconductor layers, and has a first electrode region which includes a pad area and an extension area. The insulation layer is disposed on the first semiconductor layer and at the extension area of the first electrode region. Also disclosed is a method for manufacturing the light-emitting diode.