Nano-Column Light Emitter With Moth-Eye Recesses for Light Extraction
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Solution Overview
Problem
Existing semiconductor light emitting devices with nano-columns face challenges in light extraction efficiency due to refractive index mismatch between active and cladding layers, leading to light leakage and absorption by electrodes, limiting the effectiveness of high-power, narrow-radiation angle light emission.
Innovation Solution
A light emitting device with a laminated structure featuring columnar parts and a third semiconductor layer with recessed parts that reduce refractive index variation, minimizing light loss and enhancing extraction efficiency by creating a moth-eye structure that gradually changes refractive index, thereby confining and efficiently emitting light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a nano-column structure is used to achieve narrow radiation angle and high-power light emission, then the light emission intensity is improved, but light extraction efficiency deteriorates due to refractive index mismatch between active and cladding layers
Solution Approach 1:
The invention introduces a moth-eye structure with curved recessed parts on the surface of the light emitting device. This curved surface structure gradually changes the refractive index from the high-index light emitting layer to the low-index external medium, reducing light reflection and improving extraction efficiency while maintaining the narrow radiation angle benefit of the nano-column structure
Solution Approach 2:
The invention changes the refractive index parameter gradually through the moth-eye structure by varying the depth and shape of recessed parts. This gradual parameter change reduces the abrupt refractive index mismatch between layers, minimizing light reflection and maximizing light extraction from the active layer
2Stability of the object's composition
If the refractive index difference between active layer and cladding layer is increased to improve light confinement, then light confinement is improved, but light leakage toward electrode increases causing absorption loss
Solution Approach 1:
The moth-eye structure acts as an intermediary layer between the high-refractive-index light emitting layer and the low-refractive-index external environment. This intermediate structure with graded refractive index reduces light reflection and prevents light leakage toward the electrode, thereby reducing absorption loss while maintaining light confinement
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 reduces light loss to electrodes and increases light extraction efficiency by minimizing refractive index variation and reflectance, achieving improved light emission and confinement within the light emitting layer.
Implementation Method 1
creating a moth-eye structure that gradually changes refractive index, thereby confining and efficiently emitting light
Implementation Method 2
minimizing light loss and enhancing extraction efficiency by creating a moth-eye structure that gradually changes refractive index, thereby confining and efficiently emitting light
Implementation Method 3
a light emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of generating light
Data Source
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AI summary
The light emitting device (100) includes a substrate (10), a laminated structure (20) provided to the substrate, and a plurality of columnar parts (30), wherein each columnar part includes a first semiconductor layer (32), a second semiconductor layer (36) different in conductivity type, and a light emitting layer (34) disposed between the first and the second semiconductor layers, the laminated structure includes a third semiconductor layer (38) which is connected to an opposite side to the substrate of the second semiconductor layer, and has same conductivity type as the second semiconductor layer, the second semiconductor layer (36) is disposed between the light emitting layer (34) and the third semiconductor layer (38), the third semiconductor layer is provided with a recessed part (40), an opening (41) of the recessed part is provided to a surface at an opposite side to the substrate side of the third semiconductor layer, and a diametrical size in a bottom (42) of the recessed part is smaller than a diametrical size in the opening (41) of the recessed part.