InGaN MicroLED Growth on Platelets for Sub-10 µm RGB Pixels
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Solution Overview
Problem
The development of efficient microLEDs with sub-10 µm pixel sizes is challenging due to efficiency losses from side-wall damages during dry etching, and existing methods struggle to achieve controlled emission wavelength and high external quantum efficiency for red, green, and blue pixels.
Innovation Solution
The proposed solution involves growing microLED structures on InGaN platelets monolithically grown on an epiwafer, using an upper mask layer with apertures that are smaller than the top c-plane surface, allowing for precise control of microLED growth and emission wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pixel size is decreased to achieve high resolution displays, then resolution and compact form factor are improved, but external quantum efficiency drastically decreases due to side-wall damages from dry etching
Solution Approach 1:
The device segments the microLED array into multiple discrete microLEDs, each with controlled emission characteristics. This segmentation allows individual optimization of each microLED structure to maintain efficiency while achieving small pixel sizes through precise spatial arrangement.
Solution Approach 2:
The patent applies local quality by configuring different microLED structures with specific emission wavelengths and efficiencies at different locations. Each microLED is locally optimized with controlled InGaN composition and quantum well structures to compensate for size-related efficiency losses while maintaining overall high resolution.
2Stability of the object's composition
If separate wafers are used for red, green, and blue pixels, then colour accuracy is improved, but assembly complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent merges multiple colour emissions (red, green, blue) into a single integrated microLED structure by utilizing different quantum well compositions within the same InGaN layer. This consolidation eliminates the need for separate wafers and complex pick-and-place assembly while maintaining accurate colour reproduction through controlled InGaN indium composition.
Solution Approach 2:
The InGaN-based microLED structure achieves multi-functionality by emitting multiple colours from a single material system. By varying the indium composition in quantum wells, the same structural platform can produce red, green, and blue emissions, making the device universal for full-colour display applications without requiring separate fabrication processes for each colour.
3Adaptability or versatility
If InGaN composition is increased to achieve red light emission, then wavelength coverage is improved, but external quantum efficiency and brightness decrease
Solution Approach 1:
The patent utilizes parameter changes by precisely controlling the indium composition in InGaN quantum wells to tune emission wavelength across the visible spectrum. By optimizing the indium fraction and quantum well thickness, the device achieves red light emission while maintaining acceptable quantum efficiency through careful parameter optimization rather than simply increasing indium content without control.
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 microLEDs with improved external quantum efficiency and controlled emission wavelength, overcoming the challenges of sub-10 µm pixel sizes and achieving efficient monolithic growth of RGB microLEDs on a common epiwafer.
Implementation Method 1
InGaN platelets, each being monolithically grown on the epiwafer
Implementation Method 2
a driver circuit connected by p-contacts to respective top portions of each microLED structure and by an n-contact to a base side of the epiwafer, for generating light emission from the respective microLED structure
Data Source
Figure 1
Figure 2A~2E
Figure 3A~3B
AI summary
The proposed solution relates to a semiconductor device (30) comprising an epiwafer (10) and wherein a plurality of InGaN platelets (100), each InGaN platelet being monolithically grown on the epiwafer and configured with a top c-plane surface. An upper mask layer (200) is provided with mask apertures (220) over the InGaN platelets, wherein said mask apertures have a width which is smaller than said top c-plane surface. A plurality of microLED structures (240) comprising quantum well, QW, layers (242), are grown on the top c-plane surface in one of said mask apertures. The solution further relates to a microLED device (500) comprising the semiconductor device, and a method for fabricating the semiconductor device.