Dielectric Light Collection Structures for Dense LED Pixel Arrays
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Solution Overview
Problem
Current semiconductor light-emitting arrays face challenges in maintaining high internal quantum efficiency and light extraction efficiency, especially as pixel sizes decrease below 20 μm, due to non-radiative carrier recombination at defect sites and difficult light extraction, which affects contrast and overall light output.
Innovation Solution
The semiconductor light-emitting array incorporates multiple transparent dielectric bodies that protrude from the semiconductor layer, allowing light emitted from the junction or active layer to undergo internal reflections and propagate through the dielectric bodies, enhancing light extraction efficiency and maintaining high internal quantum efficiency even at small pixel sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel sizes are decreased to increase array density, then productivity increases, but internal quantum efficiency deteriorates due to non-radiative carrier recombination at defect sites
Solution Approach 1:
The patent divides the semiconductor layer into multiple discrete pixel regions separated by dielectric bodies. This segmentation isolates the active emission areas from each other, preventing cross-talk and reducing the impact of defect sites on overall efficiency while maintaining high array density through compact pixel spacing.
Solution Approach 2:
The patent applies different material properties to different regions: the pixel regions use semiconductor materials optimized for light emission, while the separating regions use dielectric materials with different refractive indices to enhance light extraction. This local differentiation allows each region to perform its specific function optimally without compromising the other.
2Productivity
If pixel sizes are decreased to increase array density, then productivity increases, but light extraction efficiency deteriorates
Solution Approach 1:
The patent introduces dielectric bodies as intermediary structures between adjacent pixel regions. These dielectric bodies have refractive indices intermediate between the semiconductor and the surrounding medium, facilitating light extraction by reducing total internal reflection at the semiconductor-dielectric interface while maintaining compact pixel dimensions.
Solution Approach 2:
The patent adds vertical dimensionality to light extraction by positioning dielectric bodies at different heights and using their protruding structures to redirect light paths. This three-dimensional arrangement enables efficient light extraction from small pixels by utilizing vertical light propagation paths in addition to horizontal extraction.
3Loss of energy
If transparent dielectric bodies are added to enhance light extraction, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
The dielectric bodies serve multiple functions simultaneously: they act as optical intermediaries to enhance light extraction, provide physical separation between pixels to prevent cross-talk, and serve as structural supports for the pixel architecture. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent combines the light extraction function with the pixel separation function into a single integrated dielectric body structure. Rather than adding separate light extraction layers and separate isolation structures, the dielectric bodies perform both roles concurrently, simplifying the overall device architecture despite the added optical functionality.
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 configuration improves light extraction and maintains high internal quantum efficiency, achieving greater than 50% light emission from each pixel region while minimizing light emission from adjacent pixels, thus enhancing contrast and overall light output in densely packed arrays.
Implementation Method 1
some of the light emitted from the junction or active layer in the corresponding pixel region propagates into the first semiconductor layer and into the dielectric body, undergoes one or more internal reflections within the dielectric body
Data Source
AI summary
A light-emitting array includes a semiconductor LED structure, multiple transparent dielectric bodies, a set of multiple, independent first electrical contacts, and a set of second electrical contacts. The LED structure extends contiguously over the array. The second electrical contacts are in electrical contact with the second semiconductor layer. Each dielectric body protrudes away from the first semiconductor layer and has on its surface an electrically conductive layer in electrical contact with the first semiconductor layer, forming a portion of a corresponding one of the first electrical contacts. Each dielectric body and corresponding first electrical contact define a corresponding discrete, circumscribed pixel region within the contiguous area of the array, each pixel region separate from the others. Some light emitted in the pixel region propagates into the dielectric body, undergoes internal reflection(s) within the dielectric body, and propagates out of the array through the dielectric body and diode structure.