Micro-LED Display Device Lattice Constant Control

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Solution Overview

Problem

Current LED display technologies face limitations in achieving high light emitting efficiency, particularly in minimizing LED size and optimizing driving current requirements while maintaining effective wavelength conversion for color emission.

Innovation Solution

The use of micrometer-level light emitting diodes (micro-LEDs) with LTPS or IGZO thin film transistors, where the lattice constants of silicon and gallium nitride are controlled to enhance light emitting efficiency, and the ratio of gallium in the transistors is adjusted to facilitate blue light emission compatible with quantum dot materials for efficient wavelength conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If LED size is minimized to micro-LED level, then display resolution and efficiency are improved, but driving current requirements and manufacturing complexity increase

Engineering Contradiction:
Improvelight emitting efficiencyVSAvoiddriving current optimization
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the lattice constants of silicon (a-Si) and gallium nitride (a-GaN) to specific ranges. By adjusting these fundamental material parameters, the invention optimizes the electrical and optical properties of micro-LEDs, enabling efficient light emission at minimized sizes while managing driving current requirements through material composition control.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention utilizes composite materials by combining LTPS or IGZO thin film transistor materials with micro-LED structures. This composite approach integrates the electrical control functions of the transistors with the light-emitting functions of the micro-LEDs, creating a unified system that addresses both the miniaturization and driving current challenges simultaneously.

Inventive Principle:
Principle #40Composite materials

2Productivity

If lattice constants of silicon and gallium nitride are controlled to enhance light emitting efficiency, then wavelength conversion compatibility is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvelight emitting efficiencyVSAvoidlattice constant control
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent specifies precise parameter ranges for lattice constants: a-Si between 3.82-3.88 Å and a-GaN between 3.18-3.22 Å. By controlling these parameters within defined windows, the invention achieves optimal wavelength conversion compatibility while providing clear manufacturing targets that balance precision requirements with achievable production standards.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality by optimizing the lattice constants specifically in the regions where wavelength conversion occurs. The patent focuses material parameter control on the semiconductor layers directly involved in light emission and wavelength conversion, rather than uniformly across the entire device structure, thereby enhancing efficiency where it matters most while reducing overall manufacturing complexity.

Inventive Principle:
Principle #3Local quality

3Productivity

If micro-LED size is minimized, then display performance is enhanced, but stability and reliability of light emission decrease

Engineering Contradiction:
Improvedisplay performanceVSAvoidlight emission stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent employs composite materials by integrating LTPS or IGZO thin film transistors with micro-LEDs. This composite structure provides stable electrical control and protection for the miniaturized LED elements, enhancing reliability while maintaining the performance benefits of small size. The transistor-LED integration creates a robust system that mitigates the instability risks of miniaturization.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention controls critical material parameters including lattice constants and gallium ratios to optimize the stability of light emission. By maintaining specific compositional ranges in the semiconductor materials, the patent ensures that miniaturized LEDs maintain stable electrical and optical properties, preventing degradation that would otherwise occur at smaller dimensions.

Inventive Principle:
Principle #35Parameter changes

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 results in improved light emitting efficiency and stability of micro-LED displays by minimizing LED size, optimizing driving currents, and enabling effective conversion of blue light to other colors, thereby enhancing overall display performance.

Implementation Method 1

an array of micro LED device pairs are mounted within each subpixel to provide redundancy. An array of wavelength conversions layers comprising phosphor particles are formed over the array of micro LED device pairs for tunable color emission spectrum

Methodology Applied
Scientific EffectLight emitting diode effect: Light Emitting Diode

Implementation Method 2

An array of wavelength conversions layers comprising phosphor particles are formed over the array of micro LED device pairs for tunable color emission spectrum

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentEP3331011B1Display device
Publication Date: 2022.10.12 INNOLUX CORP
  • EP3331011B1 patent drawingFigure 1
  • EP3331011B1 patent drawingFigure 2
  • EP3331011B1 patent drawingFigure 3~4

AI summary

A display device is provided. The display device includes a substrate, a first transistor, and a light emitting diode. The first transistor is disposed on the substrate, wherein the first transistor comprises a first semiconductor layer comprising silicon having a first lattice constant. The light emitting diode is disposed on the substrate and electrically connected to the first transistor, wherein the light emitting diode comprises a semiconductor layer comprising gallium nitride having a second lattice constant and a third lattice constant, and the third lattice constant is greater than the second lattice constant. A ratio of the second lattice constant to the first lattice constant is greater than or equal to 0.56 and is less than or equal to 0.68.