LED Pixel Interface Texturing to Reduce Cross-Talk
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Solution Overview
Problem
As pixel size decreases in light emitting devices, cross-talk between neighboring pixels increases due to light diffusion through the converter layer, leading to poor contrast performance and illuminance inhomogeneity, especially when pixels are arranged in arrays with pitches less than 40 μm.
Innovation Solution
Introducing outcoupling textures in a central region of the interface between the pixel's epi surface and the converter layer to limit light escape while maintaining current flow, thereby enhancing contrast performance and ensuring illuminance homogeneity by selectively texturing the interface to reduce the area where light escapes from the semiconductor layer stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pixel size is decreased to increase resolution, then the pixel pitch is reduced, but cross-talk between neighboring pixels increases due to light diffusion
Solution Approach 1:
The patent segments the light extraction function by introducing outcoupling textures only in the central region of each pixel's interface, separating the light escape area from the current flow area. This segmentation allows light to be extracted efficiently from the active region while preventing lateral diffusion to neighboring pixels, thus reducing cross-talk in high-resolution displays with reduced pixel pitch
Solution Approach 2:
The patent applies local quality by creating outcoupling textures selectively in the central region rather than uniformly across the entire pixel interface. This localized texturing provides enhanced light extraction where needed (above the active region) while maintaining smooth interfaces in peripheral areas, preventing light diffusion to adjacent pixels and reducing cross-talk effects
2Manufacturing precision
If the pixel size is decreased to increase resolution, then the pixel pitch is reduced, but contrast performance deteriorates due to light diffusion
Solution Approach 1:
The patent segments the interface into a textured central region for light extraction and an untextured peripheral region for light confinement. This segmentation ensures that light is extracted vertically from the active region while being confined laterally by the smooth peripheral interface, thereby improving contrast performance in high-resolution displays with reduced pixel pitch
Solution Approach 2:
The patent applies local quality by creating outcoupling textures only in the central region above the active region, while leaving the peripheral regions smooth. This localized approach enhances light extraction efficiency where needed while maintaining sharp light boundaries that improve contrast performance and reduce optical crosstalk between adjacent pixels
3Manufacturing precision
If the physical area of the pixel is reduced to increase resolution, then the pixel pitch is reduced, but current crowding effects increase reducing Internal Quantum Efficiency
Solution Approach 1:
The patent segments the pixel interface into distinct functional regions: a central textured region for light extraction and a larger untextured region for current flow. This segmentation decouples the light extraction area from the current flow area, allowing the current flow area to maintain sufficient size for efficient carrier injection while the light extraction area is optimized for vertical light coupling, thereby preventing current crowding effects and maintaining Internal Quantum Efficiency in small-pixel displays
Solution Approach 2:
The patent applies local quality by applying outcoupling textures only in the central region where light extraction is needed, while maintaining a larger untextured area for current flow. This localized texturing ensures that the current flow area remains sufficiently large to avoid current crowding effects and maintain high Internal Quantum Efficiency, while still achieving effective light extraction in the central region above the active region
4Use of energy by moving object
If outcoupling textures are introduced across the entire interface to improve light extraction, then light extraction efficiency is improved, but light escapes from peripheral areas causing cross-talk
Solution Approach 1:
The patent applies local quality by introducing outcoupling textures only in the central region of the interface above the active region, while leaving the peripheral regions smooth. This localized texturing improves light extraction efficiency from the active region without creating additional light escape paths at the periphery, thereby preventing cross-talk between adjacent pixels while maintaining effective light coupling
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 effectively reduces cross-talk and improves contrast performance by limiting the area where light escapes, maintaining current flow, and ensuring illuminance homogeneity across pixel arrays, thus addressing the challenges of small pixel sizes and inhomogeneous illuminance.
Implementation Method 1
an interface between the first layer and a medium above the top surface of the semiconductor layer stack is roughened in an area smaller than the area of the top surface
Data Source
AI summary
In an embodiment a light emitting device includes a semiconductor layer stack with a first layer of a first doping type, a second layer of a second doping type, and an active region arranged between the first and the second layer, a first electric contact connected to an electric contact via, the electric contact via extending electrically isolated through the second layer and the active region and contacting the first layer and a second electric contact contacting the second layer, wherein the first electric contact and the second electric contact are arranged on the second layer on a bottom surface of the semiconductor layer stack, and wherein an interface between a top surface of the semiconductor layer stack and a medium above the top surface is roughened in an area smaller than an area of the top surface.