Stacked LED Epitaxial Structure for Direct Full-Color Micro Displays

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Solution Overview

Problem

Current micro LED display technologies face limitations in process efficiency and complexity for implementing color display, particularly due to challenges in mass transfer technologies and the need for beam-combining prisms or quantum dot color conversion structures.

Innovation Solution

A light-emitting diode epitaxial structure is developed with stacked monochromatic layers, each comprising a stress buffer layer, carrier injection layers, and a light-emitting layer, allowing for direct color display without the need for mass transfer or additional color conversion structures, and enabling efficient electrode signal extraction through selective etching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mass transfer technology is used to fabricate R, G, and B monochromatic LED display chips separately and then transfer them to a drive backplane, then full-color display can be implemented, but the process complexity and limitations increase significantly

Engineering Contradiction:
Improvecolor display capabilityVSAvoidprocess complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple monochromatic LED epitaxial layers (R, G, B) into a single integrated structure where different colored light-emitting layers are stacked vertically on the same substrate. This eliminates the need for separate fabrication and mass transfer processes, directly resolving the contradiction by combining multiple functions into one unified device structure.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from a planar arrangement of separate monochromatic chips to a vertical three-dimensional stacking configuration. By utilizing the vertical dimension, multiple color layers are integrated on a single substrate, fundamentally changing the spatial organization and eliminating complex transfer processes.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If beam-combining prisms or quantum dot color conversion structures are used, then color display can be achieved, but additional components and process complexity are introduced

Engineering Contradiction:
Improvecolor display capabilityVSAvoidcomponent complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the need for external beam-combining prisms or quantum dot color conversion structures by directly integrating multi-color light-emitting layers within the LED epitaxial structure itself. The color display capability is achieved through the inherent properties of different semiconductor materials in the stacked layers, not through additional optical components.

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If micro LED display size is greatly reduced and resolution is improved, then near-eye display requirements are met, but single pixel size is reduced making manufacturing more difficult

Engineering Contradiction:
Improvedisplay resolutionVSAvoidsingle pixel fabrication ease
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent segments the display into multiple functional epitaxial layers (stress buffer, carrier injection, light-emitting, etc.) that can be fabricated simultaneously using standard LED growth processes. This segmentation allows high-resolution miniaturization while maintaining manufacturability through established semiconductor fabrication techniques.

Inventive Principle:
Principle #1Segmentation

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 reduces process limitations and complexity, enabling high-resolution color display without the need for additional components, thus improving production efficiency and reducing costs.

Implementation Method 1

a light-emitting layer... The light-emitting layers in the first color epitaxial layer and the second color epitaxial layer are light-emitting layers of different colors

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

a first stress buffer layer... to improve diffusion uniformity of an injection current

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4625501A1Light-emitting diode epitaxial structure, display panel and electronic device
Publication Date: 2025.10.01 HUAWEI TECH CO LTD
  • EP4625501A1 patent drawingFigure 1~3
  • EP4625501A1 patent drawingFigure 4~6
  • EP4625501A1 patent drawingFigure 7~8

AI summary

Embodiments of this application provide a light-emitting diode epitaxial structure, a display panel, and an electronic device, and relate to the field of display technologies, to reduce process limitation on color display that is implemented by using an LED. The light-emitting diode epitaxial structure includes a first color epitaxial layer and a second color epitaxial layer that are stacked. Any one of the first color epitaxial layer and the second color epitaxial layer includes a first stress buffer layer, a first carrier injection layer, a light-emitting layer, and a second carrier injection layer that are sequentially stacked in a first direction. The light-emitting layers in the first color epitaxial layer and the second color epitaxial layer are light-emitting layers of different colors. One of the first carrier injection layer and the second carrier injection layer is an electron injection layer, and the other of the first carrier injection layer and the second carrier injection layer is a hole injection layer.