Monolithic RGB Micro-LED Arrays With Via-Defined Pixels
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Solution Overview
Problem
Conventional RGB micro LED arrays face challenges with high cost, low throughput, and limited positional accuracy in pick-and-place techniques, and inefficiencies in colour conversion methods, particularly at small pixel pitches, due to large phosphor sizes and poor light extraction efficiency in nanowire growth.
Innovation Solution
A light emitting diode structure with a p-type and n-type region configured for carrier diffusion, where vias define the perimeter of pixels and enable carrier injection, allowing for efficient light emission without the need for electron blocking layers, and using a grid via structure for tighter pixel integration and multi-colour capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pick-and-place techniques are used to assemble μLED arrays, then flexibility in component selection is improved, but manufacturing cost increases and throughput decreases
Solution Approach 1:
The patent merges the LED growth substrate with the array substrate, eliminating the need for separate component assembly. Multiple LED structures are grown simultaneously on a single substrate in a monolithic integration approach, combining what were previously separate manufacturing steps into one unified process.
Solution Approach 2:
The substrate serves multiple functions: it acts as both the growth substrate for LED formation and the final array substrate for pixel assembly. This multi-functional substrate eliminates the need for separate handling of growth and assembly substrates, improving throughput while maintaining design flexibility.
2Adaptability or versatility
If pick-and-place techniques are used to assemble μLED arrays, then component flexibility is improved, but positional accuracy deteriorates
Solution Approach 1:
The LED structures are grown directly on the array substrate in their final positions, merging the component fabrication and positioning steps. This eliminates the separate transfer and placement operations that limit positional accuracy, achieving sub-5 μm precision through direct epitaxial growth.
3Ease of manufacture
If colour conversion material is used in standard planar LED structures, then RGB colour generation is improved, but efficiency deteriorates due to small absorption coefficients
Solution Approach 1:
The patent extracts the colour conversion step entirely by growing red, green, and blue LED structures directly in their native colours through selective epitaxial growth. This eliminates the need for phosphor or quantum dot colour conversion layers, removing the associated absorption losses and efficiency problems.
Solution Approach 2:
The invention changes the fundamental approach from colour conversion to direct colour emission by controlling epitaxial growth parameters. By adjusting growth conditions and composition during semiconductor layer deposition, each pixel generates its intended colour directly, achieving high efficiency without thick conversion layers.
4Device complexity
If nanowire growth is used to form native LED arrays, then transfer complexity is reduced, but light extraction efficiency deteriorates
Solution Approach 1:
The patent uses planar epitaxial structures that replicate the successful geometry of high-efficiency planar LEDs at the micro-scale. By maintaining the proven planar structure rather than adopting novel nanowire geometries, the invention preserves excellent light extraction efficiency while achieving monolithic array integration.
5Device complexity
If nanowire growth is used to form native LED arrays, then transfer complexity is reduced, but colour gamut deteriorates due to impurity incorporation
Solution Approach 1:
The invention copies the proven epitaxial growth methodology from high-performance individual LEDs to array fabrication. By using established selective area growth techniques on planar substrates, the patent achieves excellent colour purity and gamut while simplifying the overall device integration process.
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 high-resolution, efficient, and reliable light emission with reduced etch damage and increased flexibility for RGB light generation, suitable for high-resolution displays with pixel pitches less than 10 microns.
Implementation Method 1
a light emitting region for recombination of carriers injectable by the p-type region and the n-type region
Implementation Method 2
the via defines the perimeter of a light emitting surface of at least one pixel and comprises a material configured to enable injection of carriers into the p-type region or the n-type region
Implementation Method 3
one of the p-type region and n-type region is configured such that carriers generated in the one of the p-type region and n-type region diffuses through the other one of the n-type region and the p-type region prior to recombination in the light emitting region
Data Source
Figure 1A~1C
Figure 1D~1E
Figure 1F~1G
AI summary
A light emitting diode structure comprising: a p-type region; an n-type region; a light emitting region for recombination of carriers injectable by the p-type region and the n- type region; and a via passing through the light emitting region, wherein the via defines the perimeter of a light emitting surface of at least one pixel and comprises a material configured to enable injection of carriers into the p-type region or the n-type region, wherein one of the p-type region and n-type region is configured such that carriers generated in the one of the p-type region and the n-type region diffuses through the other one of the n-type region and the p-type region prior to recombination in the light emitting region.