V-Pit Single-Chip Multi-Band LED for Phosphor-Free Emission
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) using nitride semiconductors struggle to produce multi-band light spectra at a single chip level, relying on multiple LEDs or phosphors which are costly and inefficient, and complicate the manufacturing process.
Innovation Solution
A novel light emitting diode structure featuring an n-type nitride semiconductor layer, a V-pit generation layer, and a p-type nitride semiconductor layer with an active layer having a well layer comprising a first and second well layer portion, emitting light with different peak wavelengths, allowing for multi-band light emission without the need for phosphors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single-peak monochromatic light emitting diode is used, then internal quantum efficiency is improved and light absorption loss is reduced, but mixed color light such as white light cannot be implemented
Solution Approach 1:
The active layer is divided into multiple quantum well layers (first, second, and third quantum well layers) with different compositions and thicknesses, each emitting at different wavelengths. This segmentation allows the single LED to produce multi-band light spectra while maintaining efficient light emission from each layer without requiring external phosphors or multiple LEDs.
Solution Approach 2:
Different quantum well layers are designed with specific local properties: the first quantum well layer has higher indium content for longer wavelength emission, while the second and third layers have lower indium content for shorter wavelength emission. This local quality differentiation enables wavelength-specific optimization in each layer, achieving multi-color emission from a single chip structure.
2Adaptability or versatility
If phosphors are used to convert wavelength, then mixed color 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 generation process. Instead of using phosphors to convert blue or UV light to other wavelengths, the invention directly generates multi-wavelength light through multiple quantum well layers with different bandgaps, thereby removing the source of Stoke's shift energy loss and improving overall system efficiency.
Solution Approach 2:
The patent replaces the phosphor-based optical conversion mechanism with a direct electroluminescence mechanism in multiple quantum well layers. This substitution eliminates the need for phosphor materials and the associated energy losses, achieving multi-color emission through direct electron-hole recombination in semiconductors with different bandgap energies.
3Adaptability or versatility
If multiple light emitting diodes are used to produce mixed color light, then white light can be implemented, but the process becomes complicated and preparation becomes inconvenient
Solution Approach 1:
The patent merges multiple light-emitting functions into a single LED chip by stacking multiple quantum well layers with different compositions within one active layer. This consolidation integrates what would otherwise require separate LEDs into a single device, simplifying the manufacturing process, reducing assembly complexity, and enabling white light generation from a single chip structure.
Solution Approach 2:
The single LED chip achieves multi-functionality by incorporating multiple quantum well layers that can emit different wavelengths simultaneously. This universal design allows the device to perform multiple light emission functions (blue, green, yellow, or white light) from a single chip, eliminating the need for multiple specialized LEDs and simplifying system integration.
4Adaptability or versatility
If conventional quantum well structure with varied well layer compositions is used, then multi-band light emission is attempted, but satisfactory achievement is not obtained as recombination mainly occurs in a particular well layer
Solution Approach 1:
The patent introduces an inclined interface between quantum well layers with different compositions, creating a dynamic gradient structure. This inclined interface facilitates balanced carrier distribution and recombination across all quantum well layers by reducing carrier accumulation at interfaces, enabling reliable multi-band light emission where each layer contributes effectively to the overall spectrum.
Solution Approach 2:
The patent adds a spatial dimension to the quantum well structure by creating inclined interfaces at specific angles (e.g., 45 degrees) rather than using flat horizontal interfaces. This dimensional change in the interface geometry alters carrier transport paths and distribution, enabling effective recombination and light emission from multiple quantum well layers with different compositions simultaneously.
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
Enables the production of light with multiple peak wavelengths at a single chip level, eliminating the need for phosphors and simplifying the manufacturing process, while improving efficiency and reducing costs.
Implementation Method 1
The active layer emits light having at least two peak wavelengths at a single chip level
Data Source
AI summary
A light emitting diode includes an n-type nitride semiconductor layer, a V-pit generation layer located over the n-type nitride semiconductor layer and having a V-pit, an active layer located on the V-pit generation layer, and a p-type nitride semiconductor layer located on the active layer. The active layer includes a well layer, which includes a first well layer portion formed along a flat surface of the V-pit generation layer and a second well layer portion formed in the V-pit of the V-pit generation layer. The active layer emits light having at least two peak wavelengths at a single chip level.