Micro LED Structure With InAlN Layer for Light Extraction
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Solution Overview
Problem
Current micro light-emitting diode (micro LED) displays based on GaN materials face limitations in light extraction efficiency due to refractive index mismatch between layers, leading to reduced performance.
Innovation Solution
Incorporating an n-doped InxAl(1-x)N layer with a refractive index smaller than the n-type GaN layer, along with a transparent top electrode, to enhance light extraction efficiency by reducing reflection at interfaces and increasing the thickness of layers for improved structural integrity and electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional multi-layer LED structure is used, then device complexity is reduced, but light extraction efficiency deteriorates due to significant refractive index differences between layers
Solution Approach 1:
An intermediate layer with refractive index n2 is introduced between the first layer (refractive index n1) and the second layer (refractive index n3), where n1 < n2 < n3. This intermediary layer acts as a refractive index bridge, gradually transitioning the optical properties between layers with significantly different refractive indices, thereby reducing light reflection and improving light extraction efficiency without substantially increasing device complexity
Solution Approach 2:
The refractive index parameter is gradually changed across multiple layers by selecting materials with progressively varying refractive indices. The first layer has refractive index n1, the intermediate layer has refractive index n2 (where n1 < n2 < n3), and the second layer has refractive index n3. This parameter gradient approach minimizes abrupt refractive index changes at interfaces, reducing reflection losses while maintaining a relatively simple multi-layer structure
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 significantly improves light extraction efficiency and reduces the possibility of electrical shorts, while maintaining the structural integrity of the micro LED, enhancing its performance and manufacturing flexibility.
Implementation Method 1
A refractive index of the n-doped InxAl(1-x)N layer is smaller than a refractive index of the n-type GaN layer
Data Source
AI summary
A micro light-emitting diode device includes a substrate, a micro light-emitting diode, and a transparent top electrode. The micro light-emitting diode is disposed on the substrate and includes a p-type GaN layer, an n-type GaN layer above the p-type GaN layer, an n-doped InxAl(1-x)N layer above and in contact with the n-type GaN layer, and an active layer between the p-type GaN layer and the n-type GaN layer. x is a positive number smaller than 0.5. The transparent top electrode covers and is in contact with the n-doped InxAl(1-x)N layer. A refractive index of the n-doped InxAl(1-x)N layer is smaller than a refractive index of the n-type GaN layer. A sum of the thicknesses of the n-type GaN layer and the n-doped InxAl(1-x)N layer is greater than a sum of the thicknesses of the active layer and the p-type GaN layer.