LED Light Extraction via Metallic Plasma Conversion
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) suffer from low light extraction efficiency due to near field evanescent waves being internally reflected within the semiconductor structure, leading to a significant portion of emitted light being trapped and not utilized effectively.
Innovation Solution
The LED design incorporates a horizontal structure with a substrate, semiconductor layers, optical symmetric layers, and a metallic layer, where the effective refractive index of the optical symmetric layers is carefully matched to the integrated structure, and three-dimensional nano-structures are introduced on the semiconductor layers to enhance light extraction. This configuration allows for the conversion of near field evanescent waves into metallic plasma, which is then scattered and extracted, improving the light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a standard LED structure is used, then the device is simple and easy to manufacture, but the light extraction efficiency is low due to internal reflection of near field evanescent waves
Solution Approach 1:
A metallic layer is introduced as an intermediary between the active layer and the external environment. This metallic layer converts the near field evanescent waves that would otherwise be internally reflected into metallic plasma, which can then be scattered and extracted as usable light, thereby improving light extraction efficiency without fundamentally redesigning the entire LED structure
Solution Approach 2:
The refractive index of the optical symmetric layer is carefully matched to be similar to the effective refractive index of the integrated structure (with difference Δn ≤ 0.5). This parameter optimization minimizes additional reflection at interfaces while maintaining the light extraction enhancement provided by the metallic layer and nano-structures
2Loss of energy
If optical symmetric layers with matched refractive index are added, then light extraction efficiency is improved, but the number of layers and manufacturing steps increases
Solution Approach 1:
The optical symmetric layer is designed with a refractive index carefully matched to the effective refractive index of the integrated structure (difference Δn ≤ 0.5). This parameter optimization allows the layer to minimize additional reflection while maintaining compatibility with existing manufacturing processes, reducing the impact of added complexity
Solution Approach 2:
The optical symmetric layer serves multiple functions: it acts as a refractive index matching layer to reduce reflection, provides structural support, and maintains compatibility with the metallic layer and nano-structures. This multi-functionality justifies the additional layer by providing multiple benefits from a single component
3Loss of energy
If three-dimensional nano-structures are introduced, then light extraction efficiency is enhanced, but the manufacturing process becomes more difficult
Solution Approach 1:
Three-dimensional nano-structures are introduced locally on the semiconductor layers rather than requiring complete restructuring of the entire device. This localized approach enhances light extraction at critical interfaces while maintaining the simplicity of the overall device structure and compatibility with existing manufacturing processes
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 approach significantly enhances the light extraction efficiency of LEDs by effectively converting and scattering metallic plasma, leading to increased photon emission and improved luminous efficiency compared to standard LEDs.
Implementation Method 1
near field evanescent waves emitted from the active layer are internally reflected inside the semiconductor structure
Implementation Method 2
conversion of near field evanescent waves into metallic plasma
Implementation Method 3
The effective refractive index n1 of the second optical symmetric layer 160 is similar to the effective refractive index n2 of an integrated structure
Implementation Method 4
near field evanescent waves emitted from the active layer are internally reflected inside the semiconductor structure
Implementation Method 5
three-dimensional nano-structures are introduced on the semiconductor layers to enhance light extraction. This configuration allows for the conversion of near field evanescent waves into metallic plasma, which is then scattered and extracted
Data Source
AI summary
A light emitting diode includes a substrate, a first semiconductor layer, an active layer, a second semiconductor layer, a first optical symmetric layer, a metallic layer, and a second optical symmetric layer stacked on the substrate in that sequence. A first electrode is electrically connected to the first semiconductor layer, and a second electrode is electrically connected to the second semiconductor layer. A first effective refractive index n1 of the second optical symmetric layer, a second effective refractive index n2 of an integrated structure satisfy |n1−n2|≦0.5, wherein the integrated structure includes the substrate, the first semiconductor layer, the active layer, the second semiconductor layer, and the first optical symmetric layer.