Pseudosubstrate Buffer Structure for Multi-Color LED Growth
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Solution Overview
Problem
Current methods for manufacturing optoelectronic devices with electroluminescent diodes that emit different colors are inefficient, costly, and complex, particularly due to the need for multiple substrates and color converters, which are difficult to implement in miniaturized forms and result in significant light losses.
Innovation Solution
A pseudo-substrate with a buffer structure that includes alternating layers of indium nitride and gallium nitride, allowing for the growth of electroluminescent diodes capable of emitting different wavelengths on the same substrate, eliminating the need for multiple substrates and color converters, and enabling high Indium incorporation without efficiency degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple substrates with color converters are used to produce different colored LEDs, then color diversity is achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent merges multiple substrate functions into a single substrate by creating distinct buffer structure zones (first zone with GaN buffer for blue LEDs, second zone with InGaN buffer for green LEDs, third zone with InGaN buffer for red LEDs) that can be grown simultaneously on one sapphire substrate, eliminating the need for multiple separate substrates and color converters
Solution Approach 2:
The single substrate is designed with multi-functional buffer structure zones that can support growth of different III-V compound semiconductor materials (GaN, InGaN, InGaAlN) with different compositions and properties, allowing one substrate to serve multiple color emission functions
2Adaptability or versatility
If photoluminescent pads are used as color converters, then green and red light can be obtained from blue LEDs, but light losses increase significantly
Solution Approach 1:
The invention extracts the color conversion function from separate photoluminescent pads and integrates it directly into the buffer structure zones during epitaxial growth, creating buffer zones with specific compositions (InGaN, InGaAlN) that enable direct growth of green and red emitting LEDs without intermediate photoluminescent conversion layers
Solution Approach 2:
The buffer structure zones act as intermediary layers that facilitate direct epitaxial growth of different III-V compound semiconductor materials with specific bandgaps for different colors, replacing the photoluminescent pad intermediary that caused light losses
3Adaptability or versatility
If the pick and place method is used to combine individual LED devices, then color diversity is achieved, but manufacturing time and cost increase
Solution Approach 1:
The patent combines the growth of blue, green, and red LED structures into a single epitaxial growth process on one substrate, with each buffer zone prepared for specific material growth, eliminating the need for separate fabrication and assembly steps for different color devices
Solution Approach 2:
The buffer structure zones are preliminarily prepared with specific compositions and structures (GaN buffer for blue, InGaN buffer with 5-20% In for green, InGaN buffer with 20-50% In for red) during the initial substrate preparation, enabling direct growth of corresponding color LEDs without subsequent complex manipulation steps
4Adaptability or versatility
If high Indium content is incorporated in InGaN quantum wells to achieve red emission, then wavelength tuning is possible, but efficiency of quantum wells degrades
Solution Approach 1:
The patent applies local quality by creating different buffer structure zones with specific Indium concentration ranges tailored to each color emission requirement: GaN buffer for blue, InGaN buffer with 5-20% Indium for green, and InGaN buffer with 20-50% Indium for red, allowing optimal efficiency for each wavelength range
Solution Approach 2:
The invention uses composite buffer structures combining different III-V compound semiconductor materials (GaN, InGaN, InGaAlN) with controlled compositions in different zones, enabling wavelength tuning while maintaining quantum well efficiency through optimized material composition in each specific zone
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 simplifies and economizes the manufacturing process, reduces light losses, and allows for the production of polychrome light pixels with high efficiency, overcoming the limitations of existing methods by enabling the growth of diodes emitting blue, green, and red light on a single substrate.
Implementation Method 1
Light-emitting diodes are typically formed from a semiconductor material comprising elements from group III and group V of the periodic table, such as a III-V compound, notably gallium nitride (GaN), indium gallium nitride (InGaN) or gallium aluminum nitride (AIGaN)... adapted for the growth of light-emitting diodes on the pseudo-substrate
Data Source
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AI summary
The present invention relates to a pseudosubstrate (10) for an optoelectronic device (100) suitable for the growth of light-emitting diodes (11, 12, 3) comprising a substrate (1) and a buffer structure (2) formed on an upper face (1a) of the substrate (1). The buffer structure (2) comprises at least one first portion (21) wherein one layer (211) made of solid gallium nitride (GaN) delimits at least one free surface of a first type (210) facing away from the upper face (1a) of the substrate (1), each free surface of the first type (210) being suitable for the growth on same of at least one light-emitting diode (11) mostly based on a III-V compound capable of emitting light (L1) at a first wavelength. The buffer structure (2) comprises at least one second portion (22) wherein a stack (221) alternating layers of indium and gallium nitride (InGaN) and intermediate layers of GaN and in which the indium is present in a first weight ratio, delimits at least one free surface of a second type (220) facing away from the upper face (1a) of the substrate (1), each free surface of the second type (220) being suited to the growth on same of at least one light-emitting diode (12) mostly based on a III-V compound capable of emitting light (L2) at a second wavelength different from the first wavelength. The second portion (22) of the buffer structure (2) is offset relative to the first portion (21) of the buffer structure (2) in a general plane (P) oriented parallel to the plane of the upper face (1a) of the substrate (1). The invention also describes an optoelectronic device (100) and a manufacturing method.