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, leading to a significant portion of emitted light remaining within the device.
Innovation Solution
The semiconductor structure incorporates a metallic layer as an optical symmetric center with refractive index-matched layers and three-dimensional nano-structures to amplify and scatter near field evanescent waves, enhancing light extraction efficiency by converting them into metallic plasma and uniformly distributing it across the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED structure is used, then device simplicity is maintained, but light extraction efficiency deteriorates due to internal reflection of near field evanescent waves
Solution Approach 1:
A metallic layer is introduced as an intermediary component between the active layer and the package cavity. This metallic layer serves as a mediator that converts near field evanescent waves into metallic plasma, which then radiates light outward, thereby resolving the internal reflection problem without fundamentally changing the conventional LED structure
Solution Approach 2:
The refractive index distribution is modified by introducing the metallic layer with specific optical properties. The metallic layer creates a refractive index gradient that facilitates the conversion of evanescent waves to propagating waves, improving light extraction efficiency while maintaining structural simplicity
2Loss of energy
If metallic layer with refractive index-matched layers is added, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The refractive index-matched layers are applied locally at specific interfaces within the LED structure, particularly at the metallic layer boundaries. This localized approach improves light extraction at critical interfaces without requiring comprehensive restructuring of the entire device
Solution Approach 2:
The patent employs composite material structures combining metallic layers with dielectric layers having specific refractive indices. This composite approach enables optimized optical performance through the synergistic combination of different material properties, improving light extraction while managing structural complexity
3Power
If three-dimensional nano-structures are introduced, then electron-hole recombination density is increased, but manufacturing precision requirements increase
Solution Approach 1:
Three-dimensional nano-structures are introduced to create additional spatial dimensions for electron-hole recombination. These nano-structures provide extra interfaces and volume for carrier recombination, increasing overall recombination density without requiring extreme precision in two-dimensional plane fabrication
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 increases the light extraction efficiency of LEDs by uniformly distributing metallic plasma and increasing the electron-hole recombination density, resulting in improved luminous efficiency and light extraction.
Implementation Method 1
near field evanescent waves emitted from the active layer are internally reflected inside the light emitting diode
Implementation Method 2
amplify and scatter near field evanescent waves, enhancing light extraction efficiency by converting them into metallic plasma
Implementation Method 3
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
Implementation Method 4
the visible light is emitted from the light emitting diode
Implementation Method 5
A difference between a refractive index of the first optical symmetric layer and an effective refractive index of the source layer and the buffer layer is less than or equal to 0.3
Data Source
AI summary
A light emitting diode includes a first semiconductor layer, an active layer, a second semiconductor layer, a third optical symmetric layer, a metallic layer, a fourth optical symmetric layer, and a first optical symmetric layer, a first electrode, and a second electrode. The first semiconductor layer includes a first surface and a second surface opposite to the first surface. The active layer, the second semiconductor layer, the third optical symmetric layer, the metallic layer, the fourth optical symmetric layer, and the first optical symmetric layer are stacked on the second surface in sequence. The first electrode covers and contacts the first surface. The second electrode is electrically connected with the second semiconductor layer. The first semiconductor layer, the active layer, and the second semiconductor layer constitute a source layer.