Micro LED III-Nitride Layer Stack for Lower Interface Reflection
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Solution Overview
Problem
Current micro light-emitting diode (LED) displays based on GaN materials face challenges in achieving optimal light extraction efficiency due to refractive index mismatches between layers, leading to significant light reflection and reduced brightness.
Innovation Solution
The micro light-emitting diode device incorporates a p-type III-nitride layer with sequentially stacked n-type III-nitride layers, where the top layers contain aluminum, resulting in wider band gaps and lower refractive indices, enhancing light extraction efficiency by minimizing reflections at interfaces between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED structures with uniform layer composition are used, then manufacturing is simpler, but light extraction efficiency is reduced due to high reflection at layer interfaces
Solution Approach 1:
The patent applies local quality by varying the aluminum content in different n-type III-nitride layers to create different refractive indices at specific locations. The first n-type layer has a first aluminum content while the second n-type layer has a second aluminum content, creating localized refractive index differences that reduce reflection at interfaces and improve light extraction efficiency without complicating the overall manufacturing process
Solution Approach 2:
The patent changes the refractive index parameter by adjusting the aluminum content in the n-type III-nitride layers. By controlling the aluminum composition ratio in different layers, the refractive index is optimized at each interface to minimize reflection and maximize light extraction, transforming a uniform structure into a graded-index structure that solves the light extraction problem
2Loss of energy
If multiple n-type III-nitride layers with different aluminum content are stacked, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses local quality by implementing different aluminum contents only in specific n-type layers that are critical for light extraction, rather than varying every layer. The first and second n-type layers have differentiated aluminum content to create refractive index gradients at key interfaces, while maintaining overall structural simplicity and avoiding unnecessary complexity in non-critical regions
Solution Approach 2:
The patent employs composite materials by stacking multiple n-type III-nitride layers with different aluminum compositions to create a multi-layer composite structure. This composite approach allows optimization of light extraction through refractive index matching while maintaining compatibility with standard LED fabrication processes, balancing performance improvement with manufacturing feasibility
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 significantly improves light extraction efficiency by allowing more light to propagate through the device, reducing reflections and increasing the overall brightness of the micro LED display.
Implementation Method 1
n-type III-nitride layers having varying aluminum content, resulting in progressively wider band gaps
Implementation Method 2
A refractive index of the top layer of the n-type III-nitride layers is smaller than a refractive index of the next layer of the n-type III-nitride layers
Implementation Method 3
The micro light-emitting diode includes a p-type III-nitride layer, a plurality of n-type III-nitride layers with a layer number of m sequentially stacked above the p-type III-nitride layer, and an active layer
Data Source
AI summary
A micro light-emitting diode device includes a substrate, a micro light-emitting diode, an isolation layer, and a cathode transparent electrode. The micro light-emitting diode is disposed on the substrate and includes a p-type III-nitride layer, n-type Ill-nitride layers with a layer number of m sequentially stacked above the p-type III-nitride layer, and an active layer between the p-type Ill-nitride layer and the n-type III-nitride layers. m is an integer greater than two. A top layer and a next layer in contact with each other of the n-type III-nitride layers contain aluminum. The isolation layer is on the substrate and surrounds the micro light-emitting diode. The cathode transparent electrode is at least partially in contact with a top surface of the top layer. A refractive index of the top layer is smaller than a refractive index of the next layer.