Nanostructured LED Array with Concave Reflectors
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Solution Overview
Problem
Conventional planar LED technology faces inefficiencies in light extraction due to refractive index differences between semiconductor layers and air, limiting miniaturization and material choices, and previous nanostructured LEDs have not fully optimized light extraction and fabrication for industrial production.
Innovation Solution
A nanostructured LED device comprising an array of nanostructured LEDs with associated reflectors having concave surfaces to direct light, which can be fabricated using established methods and adapted for cost-efficient industrial production, enhancing light extraction efficiency by collimating and focusing light towards the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional planar LED structure is used, then manufacturing is simple, but light extraction efficiency is poor due to refractive index differences
Solution Approach 1:
The patent transitions from planar 2D LED structure to vertical 1D nanowire structure. The nanowires are grown vertically from the substrate with active regions positioned at different heights, fundamentally changing the light emission geometry from horizontal to vertical direction, which improves light extraction by utilizing the substrate as an extraction path.
Solution Approach 2:
The patent introduces curved/refractive index gradient interfaces through the heterostructure design of nanowires with different materials (e.g., GaAs core, AlGaAs shell). The curved interfaces and graded refractive indices help redirect trapped light modes into extractable modes, improving light extraction efficiency.
2Device complexity
If planar technology is used, then device structure is simple, but miniaturization is constrained
Solution Approach 1:
The patent divides the LED into multiple discrete nanowire segments, each with its own active region. This segmentation allows independent optimization of each nanowire's dimensions and material composition, enabling miniaturization while maintaining functionality. Multiple nanowires can be densely packed to increase overall device productivity.
Solution Approach 2:
The patent employs nested heterostructure design where different material layers (e.g., GaAs core, AlGaAs shell, contact layers) are nested within each other in the radial direction of the nanowire. This nested structure enables multi-functional integration in a compact volume, supporting miniaturization.
3Adaptability or versatility
If planar technology is used, then material selection is limited by lattice matching, but nanoscale technology enables broader material choices
Solution Approach 1:
The patent extracts the lattice matching constraint by using nanowire growth methodology where the nanowire core can be grown on a substrate with different lattice constant. The nanowire structure itself accommodates the lattice mismatch through its geometry and interface design, freeing material selection from strict lattice matching requirements.
Solution Approach 2:
The patent employs composite material structures with multiple layers of different semiconductor materials (e.g., GaAs, AlGaAs, InGaAs) with different bandgaps and refractive indices. These composite nanowire heterostructures enable tailored optical and electrical properties while accommodating lattice mismatches through the nanoscale interface design.
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
The solution significantly increases the efficiency of nanostructured LED devices, allowing for effective light extraction and facilitating industrial production, while enabling the use of materials that would not match in planar technology, thus overcoming the limitations of traditional LEDs.
Implementation Method 1
The individual reflectors has a concave surface facing the active region of the respective individual nanostructured LED or active regions of group of nanostructured LEDs
Data Source
AI summary
The present invention relates to nanostructured light emitting diodes, LEDs. The nanostructure LED device according to the invention comprises an array of a plurality of individual nanostructured LEDs. Each of the nanostructured LEDs has an active region wherein light is produced. The nanostructured device further comprise a plurality of reflectors, each associated to one individual nanostructured LED (or a group of nanostructured LEDs. The individual reflectors has a concave surface facing the active region of the respective individual nanostructured LED or active regions of group of nanostructured LEDs.