Multi-color Light-emitting Device Epitaxy
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Solution Overview
Problem
Existing methods for forming multi-color light-emitting display devices face challenges such as delicate pixel alignment on small substrates, difficulty in local deposition of color conversion layers, and high costs associated with successive epitaxy sequences for achieving pixels that emit in different wavelength ranges.
Innovation Solution
A method involving the simultaneous formation of light-emitting cells with varying geometries during a single epitaxy step, using a dielectric masking layer with controlled porosity to create nanostructures of different dimensions and spacings, allowing for the emission of light in distinct wavelength ranges without the need for multiple epitaxy sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pixels are formed separately and transferred onto the same substrate, then multi-color emission is achieved, but alignment precision deteriorates for small pitch pixels
Solution Approach 1:
The patent merges the formation of multiple pixel types into a single epitaxy sequence, growing all pixel types simultaneously on the same substrate. This eliminates the need for separate fabrication and transfer processes, thereby resolving the alignment precision issue while maintaining multi-color emission capability.
Solution Approach 2:
The patent segments the pixel structures into distinct geometric configurations (planar vs. pyramidal nanostructures) that can be differentiated during a single epitaxy process. This segmentation allows each pixel type to be formed with precise control over its geometry and composition within the same growth sequence, achieving both versatility and precision.
2Adaptability or versatility
If color conversion layers are deposited locally on pixels, then wavelength conversion is achieved, but manufacturing complexity increases for small pixels
Solution Approach 1:
Instead of converting the wavelength of emitted light using color conversion layers, the patent inverts the approach by directly engineering the light-emitting cells to emit at the desired wavelengths through compositional control during epitaxy. This eliminates the need for separate color conversion layers and simplifies the manufacturing process.
3Adaptability or versatility
If successive epitaxy sequences are used to form different pixel types, then multi-color emission is achieved, but manufacturing cost increases
Solution Approach 1:
The patent combines the formation of multiple pixel types into a single epitaxy sequence, performing all necessary growth steps simultaneously rather than sequentially. This merging of processes reduces manufacturing time, equipment usage, and overall production cost while maintaining the ability to produce different pixel types with distinct emission characteristics.
4Area of stationary object
If pixels are made with small pitch, then display resolution is improved, but alignment difficulty increases
Solution Approach 1:
By merging the formation of all pixel types into a single epitaxy process on a common substrate, the patent eliminates alignment operations entirely. The small pitch pixels are formed in-situ with precise spatial control, achieving high display resolution without the alignment difficulties that would arise from separate fabrication and transfer processes.
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
Enables the cost-effective and precise formation of multi-color light-emitting display devices with pixels emitting in different wavelength ranges, overcoming alignment and durability issues while reducing manufacturing complexity and cost.
Implementation Method 1
each pixel comprises a light-emitting cell comprising a stack of a first doped semiconductor layer of a first conductivity type, of an active layer, and of a second doped semiconductor layer of the second conductivity type. In operation, an electric current is applied between the first and second semiconductor layers of the cell. Under the effect of this current, the active layer emits a light ray in a wavelength range which essentially depends on its composition.
Implementation Method 2
A method is provided for the simultaneous formation, during a same epitaxy sequence, of light-emitting cells of different types respectively capable of emitting in different wavelength ranges
Data Source
AI summary
A light-emitting device including first, second, and third pixels, wherein: the first pixel includes a two-dimensional light-emitting cell including a vertical stack of a first semiconductor layer of a first conductivity type, of an active layer, and of a second semiconductor layer of the second conductivity type; each of the second and third pixels includes a three-dimensional light-emitting cell including a plurality of nanostructures of same dimensions regularly distributed across the surface of the pixel, each nanostructure including a doped pyramidal semiconductor core of the first conductivity type, an active layer coating the lateral walls of the core, and a doped semiconductor layer of the second conductivity type coating the active layer; and the nanostructures of the second and third pixels have different dimensions and/or a different spacing.