Color-Filtering DBR Structure for MicroLED Color Purity
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Solution Overview
Problem
Current microLED technologies face challenges in enhancing light emission efficiency, electrical conductivity, reducing optical cross-talk between pixels, and achieving uniformity in large-scale wafer fabrication, particularly in the fabrication of monolithic RGB microLEDs.
Innovation Solution
The use of electrochemical etching assisted by dry-etched apertures to create nanoporous DBR layers, providing n-type electrical contacts, forming gaps with light-blocking materials between pixels, and designing optical resonant cavities to enhance light output and collimation, while also acting as filters to purify color through spectrum engineering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional DBR fabrication methods are used, then manufacturing simplicity is maintained, but light emission efficiency and color purity are insufficient
Solution Approach 1:
The patent applies porous silicon layers within the DBR structure to enhance light emission efficiency. The porous structure increases the effective surface area and improves light extraction efficiency, directly addressing the illumination intensity parameter while maintaining the layered DBR architecture for manageable fabrication complexity
Solution Approach 2:
The patent employs composite DBR structures combining multiple materials including silicon nitride, silicon oxide, and porous silicon layers. This composite approach enables optimization of optical properties for enhanced light emission while the systematic layering provides a structured fabrication process that manages complexity
2Object-affected harmful factors
If standard DBR structures are used, then fabrication uniformity is easier to achieve, but optical cross-talk between pixels increases
Solution Approach 1:
The patent introduces pixel isolation structures that segment the optical paths between adjacent microLED pixels. These isolation elements prevent light from one pixel from interfering with adjacent pixels, directly reducing optical cross-talk while the segmentation is integrated into the overall DBR fabrication process to maintain uniformity
Solution Approach 2:
The patent implements localized modifications to the DBR structure at pixel boundaries, such as varying the thickness or material composition in specific regions. This local quality adjustment enables targeted reduction of optical cross-talk at interfaces while maintaining the overall uniformity and manufacturability of the large-area DBR structure
3Manufacturing precision
If complex packaging processes are used, then color purity can be improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent performs preliminary color filtering and spectrum engineering directly during the DBR fabrication process rather than requiring subsequent packaging steps. The DBR layers are designed with specific thicknesses and materials that pre-filter the LED emission spectrum, achieving color purity before the devices are packaged, thereby eliminating complex post-fabrication processing
Solution Approach 2:
The patent designs the DBR structure to serve multiple functions simultaneously: it provides optical reflection, color filtering, and spectrum engineering all in one integrated component. This multi-functionality eliminates the need for separate packaging processes to achieve color purity, reducing both manufacturing complexity and cost while maintaining high color quality
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 significantly enhances light emission efficiency, improves electrical conductivity, reduces optical cross-talk, and achieves high uniformity across large wafers, enabling efficient fabrication of high-quality microLEDs with improved color purity and reduced need for complex packaging processes.
Implementation Method 1
a first plurality of DBR layers forming a red-light DBR configured to reflect light at a wavelength of light emitted by the red microLED, a second plurality of DBR layers forming a green-light DBR configured to reflect light at a wavelength of light emitted by the green microLED, and a third plurality of DBR layers forming a blue-light DBR configured to reflect light at a wavelength of light emitted by the blue microLED
Implementation Method 2
The use of electrochemical etching assisted by dry-etched apertures to create nanoporous DBR layers
Implementation Method 3
designing optical resonant cavities to enhance light output and collimation
Data Source
AI summary
A device includes a light emitting diode (LED) configured to emit light characterized by a peak wavelength, a lower wavelength band extending across lower wavelengths than the peak wavelength, and a higher wavelength band extending across higher wavelengths than the peak wavelength. The device also includes a reflector positioned in a first direction from the LED. The device also includes a distributed Bragg reflector (DBR) having a lower reflectance than the reflector, positioned in a second direction from the LED opposite the first direction, and configured to block light within a stopband overlapping a portion of the lower wavelength band or a portion of the higher wavelength band but not overlapping the peak wavelength, such that the DBR propagates filtered light in the second direction.