Multi-Wavelength LED Structure Without Phosphor Resin
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Solution Overview
Problem
Existing white light emitting devices that use phosphors are complicated to manufacture and costly, with the phosphor resin being prone to heat degradation over time.
Innovation Solution
A light emitting device that combines a short wavelength light emitting portion and a long wavelength light emitting portion without using a phosphor, utilizing a coupling layer to integrate these portions and allowing for multi-wavelength light emission, such as white light, at the wafer or chip level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor resin is used to convert blue light to yellow light for white light emission, then white light can be generated, but the manufacturing process becomes complicated and production cost increases
Solution Approach 1:
The patent merges the blue light emitting portion and yellow light emitting portion into a single integrated LED structure. The blue light portion uses a GaN-based active layer while the yellow light portion uses an InGaAlP-based active layer, both grown on the same sapphire substrate. This integration eliminates the need for separate phosphor resin application and curing processes, simplifying manufacturing while maintaining white light emission capability.
2Illumination intensity
If a phosphor resin is used for wavelength conversion, then yellow light can be generated from blue light, but the resin deteriorates over time due to heat resistance issues
Solution Approach 1:
The patent replaces the organic phosphor resin system with an inorganic semiconductor-based light emitting portion. The yellow light is generated directly by an InGaAlP-based active layer that converts electrical energy to light through electroluminescence, eliminating the need for thermal phosphor conversion. This substitution provides superior heat resistance and long-term reliability while maintaining yellow light emission.
3Adaptability or versatility
If multiple LED chips are used to achieve multi-wavelength emission, then various wavelengths can be emitted, but the device structure becomes more complex
Solution Approach 1:
The patent combines multiple wavelength-emitting functionalities within a single LED chip structure. The device includes a blue light emitting portion with GaN-based active layer and a yellow light emitting portion with InGaAlP-based active layer, both integrated on one sapphire substrate with shared electrode structures. This merging approach achieves multi-wavelength emission without requiring multiple separate chips, thereby reducing structural complexity.
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 simplifies the manufacturing process, reduces production costs, and enhances durability by eliminating heat-sensitive phosphor resin, while achieving multi-wavelength light emission.
Implementation Method 1
Each of the short wavelength light emitting portion and the long wavelength light emitting portion includes a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer
Data Source
AI summary
A light emitting device includes a short wavelength light emitting portion, a long wavelength light emitting portion, and a coupling layer combining the short wavelength emitting portion and the long wavelength light emitting portion. Each of the short wavelength light emitting portion and the long wavelength light emitting portion includes a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer. The active layer of the long wavelength light emitting portion contains more Indium (In) than the active layer of the short wavelength light emitting portion, and the short wavelength light emitting portion emits light of a shorter wavelength than that of light emitted from the long wavelength light emitting portion.