Monolithic InGaN Pixel Structure for Direct RGB Emission
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Solution Overview
Problem
Current optoelectronic devices for display screens and image projection systems face challenges in efficiently producing multiple colors without mechanical manipulation, high light output, and maintaining indium content in InGaN quantum wells, while avoiding the use of InGaAIP and interposed electronic insulators.
Innovation Solution
A monolithic architecture using stacks of indium gallium nitride (InGaN) and gallium nitride (GaN) layers with varying indium concentrations and doping, allowing for the generation of multiple colors within the same pixel without mechanical manipulation, high indium content, and eliminating the need for InGaAIP and interposed insulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate substrates are used to fabricate LEDs of different colors and then combined using pick and place method, then each pixel can emit multiple colors, but the manufacturing process becomes complex, time-consuming, and costly with numerous connections required
Solution Approach 1:
The patent combines multiple LED structures emitting different colors (blue, green, red) into a single monolithic substrate, eliminating the need for separate substrates and pick-and-place assembly. This merging approach reduces manufacturing complexity while maintaining multi-color emission capability in each pixel
Solution Approach 2:
The invention creates a universal substrate that can simultaneously support multiple LED structures with different emission colors using the same formation technique. This universal platform eliminates the need for color-specific substrates and complex assembly processes
2Illumination intensity
If InGaAlP material is used to obtain red color, then red light can be emitted, but the wavelength varies significantly with temperature and the material growth is delicate
Solution Approach 1:
The patent changes the material composition parameters by using InGaN-based quantum wells with controlled indium concentrations instead of InGaAlP. This parameter change achieves red light emission while improving wavelength stability against temperature variations and simplifying material growth
3Reliability
If an intervening layer of electronic insulator is introduced in the layer assembly, then electrical isolation is achieved, but the formation of electrical contact points becomes complex and parasitic capacitances are generated
Solution Approach 1:
The invention removes the intervening electronic insulator layer from the structure. By extracting this problematic layer, the patent simplifies contact formation while managing electrical isolation through alternative means, thereby reducing parasitic capacitances and manufacturing complexity
4Adaptability or versatility
If photoluminescent pads are used as color converters to enable green and red light emission, then color conversion is achieved, but significant light loss occurs with conversion rates between 50% and 80%
Solution Approach 1:
The patent replaces the photoluminescent conversion mechanism with direct electroluminescence from InGaN-based quantum wells. This substitution eliminates the intermediate photoluminescent conversion step, thereby avoiding significant light loss and achieving higher overall emission efficiency
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 solution enables simple and economical manufacturing of optoelectronic devices with high light output, efficient color generation, and reduced manufacturing time and connections, while maintaining indium content and avoiding the use of InGaAIP and interposed insulators.
Implementation Method 1
each light-emitting diode comprises an active layer exploiting quantum wells
Implementation Method 2
an active layer exploiting quantum wells
Implementation Method 3
photoluminescent pads that act as color converters at the sub-pixel level. Each photoluminescent pad is designed to absorb at least some of the blue light emitted by the LEDs and convert it into green or red light
Data Source
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AI summary
An optoelectronic device (10) comprises at least one primary sub-pixel (112) comprising at least one first primary stack (103a) which comprises at least two first main layers (100b) of indium nitride and gallium nitride having the formula lnzGai-zN, wherein 0 < z < 0.l, said layers being separated in pairs at least by a first intermediate layer (100a) of gallium nitride; at least a first primary active layer (104a) with at least one first quantum well; at least one second primary stack (105a) comprising at least two second main layers (100b) of indium nitride and gallium nitride having the formula lnxGai-xN wherein 0.l ≤ x < 0.2, said layers being separated in pairs at least by a second intermediate layer (100a) of gallium nitride; at least one second primary active layer (106a) with at least one second quantum well; and a first primary junction layer (109d) which is formed on the second primary active layer (106a) and in contact with the second primary active layer (106a), the first primary junction layer (109d) being doped according to a second type of doping chosen from an N-type doping and a P-type doping, the second type of doping being different from the first type of doping. A manufacturing method is also described.