Multi-Bandgap Light-Emitting Structure With V-Grooves for Light Extraction
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Solution Overview
Problem
Existing light emitting devices suffer from inefficiencies in luminous efficacy and light emission due to imbalances among their components.
Innovation Solution
A light emitting device with a multi-quantum well structure and V-shaped grooves in the active layer, featuring sub-active layers with varying energy bandgaps and a light control layer, enhances light extraction and dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional light emitting device structure is used, then the device is simple to manufacture, but the luminous efficacy and light emission efficiency deteriorate due to component imbalance
Solution Approach 1:
The active layer is divided into multiple sub-active layers (first sub-active layer 152, second sub-active layer 154) with different energy bandgaps, each contributing to different wavelength ranges. This segmentation allows optimization of light emission across the spectrum while maintaining manufacturing feasibility through sequential layer formation.
Solution Approach 2:
Different regions of the device are given different properties: the first sub-active layer has a first energy bandgap optimized for certain wavelengths, the second sub-active layer has a second energy bandgap for complementary wavelengths, and the boundary layer has specific Al content for carrier confinement. This local optimization of properties throughout the device structure improves overall luminous efficacy without excessive complexity.
2Productivity
If sub-active layers with different energy bandgaps are used, then light emission efficiency improves, but the manufacturing process becomes more complex
Solution Approach 1:
The light control layer 140 is formed beforehand to create the V-shaped groove structure before depositing the active layer materials. This preliminary structuring enables subsequent layers to be deposited conformally, simplifying the overall manufacturing process despite the multi-layer complexity.
Solution Approach 2:
The energy bandgap parameters are systematically varied across sub-active layers by controlling composition gradients (e.g., Al content in AlGaN). This parameter optimization is achieved through standard epitaxial growth techniques, maintaining ease of manufacture while improving light emission efficiency across different wavelength ranges.
3Illumination intensity
If V-shaped grooves are formed in the active layer, then light extraction and dispersion improve, but the device structure becomes more complex
Solution Approach 1:
V-shaped grooves with curved profiles are formed in the active layer instead of straight trenches. The curved geometry provides superior light scattering and extraction compared to linear structures, while the grooves can be formed using standard photolithography and etching processes, limiting the increase in device complexity.
Solution Approach 2:
The V-shaped grooves introduce vertical and lateral dimensional variations into the otherwise planar active layer. This multi-dimensional structuring creates multiple light extraction pathways and enhances dispersion without requiring additional lateral expansion of the device footprint.
4Reliability
If the boundary layer with Al is added between active layer and P-type layer, then carrier confinement and light emission improve, but the number of layers increases
Solution Approach 1:
The boundary layer 161 acts as an intermediary between the active layer and P-type semiconductor layer, providing carrier confinement through its higher Al content. This intermediate layer mediates the transition between regions with different properties, improving operational stability while adding only a single functional layer rather than multiple complex structures.
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 device achieves high efficiency, stable operation, and reliability by optimizing light emission through structured active layers and scattering mechanisms.
Implementation Method 1
an active layer (150) disposed on the first conductivity type semiconductor layer (130), and a second conductivity type semiconductor layer (160) disposed on the active layer (150)... a first sub-active layer (152) formed on the first conductive-type semiconductor layer (130) and having a first energy bandgap; and a second sub-active layer (154) formed on the first sub-active layer (152) and having a second energy bandgap different from the first energy bandgap
Implementation Method 2
a light control layer (140) disposed between the first conductive-type semiconductor layer (130) and the active layer (150) to form a light control structure V within the active layer (150)... the light control structure (V) may be a V-shaped groove (V) having a V-shaped cross-section across the active layer (150)
Implementation Method 3
the boundary layer (161) may cover a surface of the V-shaped groove (V) to form a boundary between the V-shaped groove (V) and the p-type semiconductor layer... an effective index of refraction of the boundary layer (161) may be less than an effective index of refraction of the p-type semiconductor layer
Data Source
Figure 1
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Figure 4
AI summary
A light emitting device and a light emitting apparatus including the same are disclosed. The light emitting apparatus includes a light emitting device (100) and a circuit substrate (200) on which the light emitting device (100) is mounted. The light emitting device (100) includes a first conductivity type semiconductor layer (130), an active layer 150 disposed on the first conductivity type semiconductor layer 130, and a second conductivity type semiconductor layer 160 disposed on the active layer 150, wherein the active layer 150 includes a plurality of sub-active layers 152, 154 having different energy bandgaps.