Single-Chip Multi-Band LED Structure Without Phosphor Conversion
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Solution Overview
Problem
Existing light emitting diodes using nitride semiconductors struggle to produce multi-band light efficiently without the use of phosphors, which are costly and inefficient, and mixing multiple diodes complicates the process.
Innovation Solution
A novel light emitting diode structure with a V-pit generation layer, an active layer having two well regions, and a sub-emission layer between the n-type and p-type nitride semiconductor layers, allowing for the emission of at least two different peak wavelengths at a single chip level, including a sub-emission layer to control and enhance the emission of shorter wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If phosphors are used to convert wavelength to achieve multi-band light emission, then white light can be produced, but cost increases and efficiency decreases due to Stoke's shift
Solution Approach 1:
The patent extracts and eliminates the phosphor conversion step from the light emission system. By directly incorporating multiple quantum well regions with different bandgaps in the active layer, the device generates multi-band light through direct electron-hole recombination without requiring phosphor materials, thereby removing the source of Stoke's shift energy loss.
Solution Approach 2:
The patent introduces an electron blocking layer as an intermediary component between the n-type and p-type contact layers. This layer mediates carrier distribution to ensure efficient recombination in each quantum well region while preventing carrier leakage, thereby maintaining high efficiency across multiple emission bands without requiring phosphor conversion.
2Adaptability or versatility
If multiple light emitting diodes are mixed together to produce white light, then multi-band emission is achieved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges multiple light emission functions into a single integrated active layer by stacking multiple quantum well regions with different compositions and bandgaps. This consolidation allows one LED chip to perform the function of multiple separate LEDs, simplifying the overall device structure and manufacturing process while maintaining multi-band emission capability.
Solution Approach 2:
The active layer is designed with multi-functionality by incorporating quantum well regions that emit at different wavelengths (e.g., blue, green, yellow) within a single structure. This universal design enables one device to replace multiple specialized LEDs, reducing system complexity and facilitating easier manufacturing and integration.
3Adaptability or versatility
If conventional quantum well structure is used with varied well layer compositions to achieve multi-band light, then light emission occurs, but recombination mainly occurs in a particular well layer reducing efficiency
Solution Approach 1:
The patent applies local quality by creating distinct quantum well regions with different compositions, thicknesses, and positions within the active layer. Each region is locally optimized for specific wavelength emission, and the electron blocking layer locally controls carrier distribution to ensure efficient recombination occurs simultaneously across multiple regions rather than being concentrated in a single well layer.
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 enables efficient production of multi-band light, including white light with adjustable correlated color temperature, reducing the need for phosphors and simplifying the manufacturing process.
Implementation Method 1
the sub-emission layer may emit light having a peak wavelength within a region of wavelengths shorter than a peak wavelength of the first well region
Implementation Method 2
it is difficult to generate light having multi-bands because recombination of electrons and holes mainly occurs in a particular well layer
Data Source
AI summary
A light emitting diode includes an n-type nitride semiconductor layer, a V-pit generation layer disposed on the n-type nitride semiconductor layer and having V-pits, an active layer disposed on the V-pit generation layer and including a first well region formed along a flat surface of the V-pit generation layer and a second well region formed in the V-pit of the V-pit generation layer, a p-type nitride semiconductor layer disposed on the active layer and a sub-emission layer interposed between the n-type nitride semiconductor layer and the p-type nitride semiconductor layer and disposed near the active layer. The sub-emission layer may emit light having a peak wavelength within a range of wavelengths shorter than a peak wavelength of the first well region, and light emitted from the light emitting diode is within a range of 0.205≤X≤0.495 and 0.265≤Y≤0.450 in CIE color coordinates (X, Y).