Monolithic LED V-Groove Indium Grading for Strain Relief
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in producing red light efficiently due to strain and solubility issues in the III-N material system, leading to increased complexity and cost in fabricating multiple LEDs for different colors, and existing solutions like color converters or Europium doping are not ideal for large-scale manufacturing.
Innovation Solution
A monolithic LED system with a multiple quantum well (MQW) region featuring parallel layers doped with Indium and V-grooves of varying Indium concentration, allowing for a range of light emissions between 400 and 600 nm, enabling color-tunability without the need for color converters or separate MQW regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If Indium concentration is increased to produce red light in InGaN/GaN MQWs, then longer wavelength emission is achieved, but strain and solubility issues arise leading to low efficiency
Solution Approach 1:
The patent applies local quality by creating V-grooves with different Indium concentrations in specific regions of the MQW structure. The V-grooves contain lower Indium concentration (reducing strain) while the regions between V-grooves have higher Indium concentration (enabling red light emission). This spatial variation in composition allows the device to achieve long wavelength emission without suffering from the strain and solubility limitations that plague uniform high-Indium structures.
2Adaptability or versatility
If separate LEDs are used for different colors (blue, green, red), then desired wavelengths can be achieved, but fabrication cost and integration complexity increase
Solution Approach 1:
The patent merges multiple wavelength-emitting regions into a single monolithic LED device. By incorporating V-grooves with varying Indium concentrations within one InGaN/GaN MQW structure, the device can emit blue, green, and red light simultaneously from different regions. This eliminates the need for separate LEDs and their associated packaging and integration complexity, while maintaining the ability to produce multiple desired wavelengths.
Solution Approach 2:
The patent creates a universal LED structure that can perform multiple wavelength emission functions within a single device. The MQW region with V-grooves serves as a multi-functional element that can generate different colors (blue, green, red) depending on the Indium concentration in different regions, replacing what would traditionally require three separate specialized LEDs.
3Adaptability or versatility
If color converters (quantum dots or phosphors) are used with blue LEDs, then red and green light can be generated, but manufacturing steps and cost increase
Solution Approach 1:
The patent extracts the color conversion function from separate phosphor or quantum dot layers and integrates it directly into the MQW active region. Instead of using a blue LED with phosphor coatings applied afterward, the Indium-rich regions within the V-groove structure directly generate red and green light through electroluminescence, eliminating the need for post-growth phosphor deposition and reducing manufacturing steps.
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
This approach enables monolithic multi-color LEDs with reduced complexity and cost, improved performance, and the ability to produce a variety of peak wavelengths in response to driving current density, suitable for applications like displays and commercial lighting, without requiring Europium doping or increased Indium percentages.
Implementation Method 1
The MQW region is composed of multiple individual quantum wells which possess a smaller energy bandgap due to alloying, that are positioned between higher energy bandgap materials. The smaller energy bandgap quantum wells confine electrons and holes to facilitate recombination and corresponding light emission.
Implementation Method 2
The MQW region includes parallel layers, each doped with a percentage of Indium to enable a range of light emission between 400 and 600 nm
Implementation Method 3
Indium is alloyed with GaN in different amounts to shrink the bandgap of the quantum wells. By way of example for LEDs based on the III-N material system, Indium is alloyed with GaN in different amounts to shrink the bandgap of the quantum wells.
Data Source
AI summary
A monolithic LED system that is configured to emit a variety of peak wavelengths of light in response to variations in a driving current density includes an n-type region, a p-type region, and a multiple quantum well (MQW) region formed between the n-type region and the p-type region. The MQW region includes parallel layers, each doped with a percentage of Indium to enable a range of light emission between 400 and 600 nm, and one or more V-grooves formed within a portion of the parallel layers. Each of the one or more V-grooves has a lower concentration of the doped percentage of the Indium than other portions of the parallel layers. Transition regions between the one or more V-grooves and the other portions of the parallel layers have a higher concentration of the doped percentage of the Indium which decreases with distance from the one or more V-grooves.