LED Optical Symmetric Layer for Light Extraction
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Solution Overview
Problem
Semiconductor structures used in light emitting diodes (LEDs) face low light extraction efficiency due to near field evanescent waves being internally reflected, reducing the overall emission of visible light.
Innovation Solution
A semiconductor structure is designed with a substrate, composite semiconductor layer, first and second optical symmetric layers, and a metallic layer, where the refractive indices of these layers are carefully selected to minimize heat conversion and maximize the extraction of metallic plasma, enhancing light extraction efficiency through the use of three-dimensional nano-structures on the semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a standard semiconductor structure is used with N-type and P-type layers, then the LED can operate and emit visible light, but near field evanescent waves are internally reflected causing low light extraction efficiency
Solution Approach 1:
The patent introduces an optical symmetric layer with a specific refractive index (1.3-1.5) as an intermediary between the semiconductor layer and the metallic layer. This intermediate layer acts as a mediator that facilitates the conversion of near field evanescent waves into propagating light waves, enabling efficient light extraction while maintaining the basic LED structure and operation
2Illumination intensity
If the refractive index difference between layers is increased to improve light extraction, then more light can be extracted, but heat conversion increases reducing overall efficiency
Solution Approach 1:
The patent optimizes the refractive index parameter of the optical symmetric layer to be within 1.3-1.5, which is a specific parameter range that balances light extraction efficiency with heat generation. By carefully selecting this parameter, the system achieves effective light extraction while minimizing excessive heat conversion that would reduce overall efficiency
3Illumination intensity
If metallic plasma extraction is maximized to improve light emission, then photon emission increases, but device complexity increases due to additional layers and nano-structures
Solution Approach 1:
The patent divides the light extraction function into distinct segments: the optical symmetric layer handles the initial wave conversion, the metallic layer handles plasma generation and extraction, and the three-dimensional nano-structures handle light scattering and directional control. This segmentation allows each component to be optimized for its specific function while working together to achieve high photon emission
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 structure significantly improves light extraction efficiency by amplifying and converting near field evanescent waves into metallic plasma, which is then scattered and extracted, leading to increased photon emission and improved current uniformity.
Implementation Method 1
near field evanescent waves emitted from the active layer are internally reflected inside the semiconductor structure
Implementation Method 2
amplifying and converting near field evanescent waves into metallic plasma
Implementation Method 3
scattered and extracted, leading to increased photon emission
Implementation Method 4
the refractive indices of these layers are carefully selected to minimize heat conversion and maximize the extraction of metallic plasma
Implementation Method 5
near field evanescent waves emitted from the active layer are internally reflected inside the semiconductor structure
Implementation Method 6
holes in the P-type semiconductor layer and electrons in the N-type semiconductor layer can enter the active layer and combine with each other to emit visible light
Data Source
AI summary
A light emitting diode includes 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 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 and 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.