Monolithic RGB Pixel Structure Using InGaN Quantum Wells
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Solution Overview
Problem
Current optoelectronic devices face challenges in producing pixels that emit multiple colors, such as blue, green, and red, without mechanical handling, while maintaining high luminous efficiency and avoiding the use of inefficient materials like InGaAIP, which has wavelength variations and efficiency issues with miniaturization.
Innovation Solution
The implementation of an optoelectronic device with a monolithic architecture using indium and gallium nitride stacks with varying indium concentrations in quantum wells, allowing for the emission of different colors without color converters, and eliminating the need for mechanical handling and electronic insulator layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the pick and place method is used to assemble individual light-emitting diodes for different colors, then multiple colors can be achieved in each pixel, but the manufacturing process becomes complex, time-consuming, and costly with many connections required
Solution Approach 1:
The patent merges multiple light-emitting diodes of different colors into a single integrated device structure. Instead of separately manufacturing and assembling individual LEDs for red, green, and blue colors, the invention creates a unified LED with multiple active regions that emit different colors simultaneously, eliminating the need for complex pick-and-place assembly processes
Solution Approach 2:
The patent creates a universal light-emitting diode structure that can emit multiple colors through a single device. The multi-color LED incorporates different quantum well compositions within the same device, allowing it to function as both a red, green, and blue light source simultaneously, replacing the need for multiple separate LEDs
2Adaptability or versatility
If InGaAIP material is used to obtain red color, then red emission can be achieved, but the wavelength varies considerably with temperature and efficiency decreases for micro diodes smaller than 30 microns
Solution Approach 1:
The patent changes the material composition parameters by using InGaN quantum wells with high indium content (In0.2Ga0.8N and In0.3Ga0.7N) instead of InGaAIP. This parameter change maintains red emission capability while improving wavelength stability against temperature variations and maintaining efficiency in miniaturized structures
Solution Approach 2:
The patent employs composite material structures with alternating layers of In0.2Ga0.8N and In0.3Ga0.7N quantum wells separated by GaN barriers. This composite approach combines the advantages of different indium compositions to achieve stable red emission with improved temperature characteristics and maintained efficiency at small dimensions
3Adaptability or versatility
If photoluminescent pads are used as color converters to emit green and red light from blue LEDs, then color conversion can be achieved, but light losses are high with conversion rates between 50% and 80%
Solution Approach 1:
The patent extracts the color conversion function entirely by generating all three primary colors (red, green, and blue) directly from the light-emitting diode itself through multiple quantum well active regions. This eliminates the need for external photoluminescent pads and their associated energy losses, achieving near-100% conversion efficiency
4Reliability
If electronic insulator layers are introduced in the assembly, then electrical isolation can be achieved, but the formation of electrical contacts becomes complex and parasitic capacitances are generated
Solution Approach 1:
The patent removes electronic insulator layers from the device structure entirely. By designing the multi-color LED with integrated electrical contacts that directly access the active regions through the semiconductor layers, the invention achieves electrical isolation through the inherent semiconductor structure and doping profiles without requiring additional insulator layers, thereby simplifying contact formation and reducing parasitic capacitances
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 the production of high-luminous efficiency devices with multiple colors in a single pixel, reducing manufacturing complexity and costs, and avoiding the limitations of InGaAIP, while maintaining indium concentrations above 20% in InGaN quantum wells.
Implementation Method 1
each light-emitting diode comprises an active layer exploiting quantum wells
Implementation Method 2
each light-emitting diode comprises an active layer exploiting quantum wells
Data Source
AI summary
An optoelectronic device includes at least one primary sub-pixel having at least one first primary stack with at least two first main layers of indium nitride and gallium nitride, the layers separated in pairs at least by a first intermediate layer of gallium nitride. The device includes a first primary active layer with at least one first quantum well, and a second primary stack having at least two second main layers of indium nitride and gallium nitride the layers separated in pairs by a second intermediate layer of gallium nitride; at least one second primary active layer with one second quantum well; and a first primary junction layer formed on and in contact with the second primary active layer, the first primary junction layer doped according to a second type of doping chosen from an N-type and a P-type dopings, the second type of doping different from the first type.