Stacked Epitaxial Micro-LED Structure for Larger Emitting Area
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Solution Overview
Problem
Micro-LED displays face challenges in mounting and achieving high-resolution, full-color display with high color purity due to the small size of micro-LEDs, requiring a method to increase light emitting area without increasing pixel area and simplify manufacturing.
Innovation Solution
A light emitting stacked structure with epitaxial sub-units of different colors, where each sub-unit has a unique light emitting area that overlaps with others, allowing for efficient light transmission and independent drive, enabling a compact and simplified manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If micro-LEDs are arranged on a two-dimensional plane to achieve high-resolution display, then the number of micro-LEDs required increases to hundreds of thousands or millions, but mounting difficulty increases due to the very small size of each micro-LED
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of micro-LEDs to a three-dimensional stacked structure. Multiple epitaxial sub-units are vertically stacked on a single substrate, with each sub-unit emitting different colored light. This vertical stacking allows multiple light-emitting elements to occupy the same planar footprint, dramatically reducing the number of individual mounting operations required while maintaining high display resolution.
Solution Approach 2:
The patent combines multiple micro-LED epitaxial sub-units into a single integrated stacked structure. Instead of separately mounting hundreds of thousands of individual micro-LEDs, the invention merges them into vertically stacked assemblies where multiple sub-units share common bonding pads and control circuits, significantly simplifying the mounting process.
2Measurement precision
If the area of each micro-LED is reduced to increase the number of pixels, then display resolution improves, but light emitting area per pixel decreases
Solution Approach 1:
The patent compensates for the reduced planar area of each micro-LED by extending the light-emitting structure vertically. Multiple epitaxial sub-units are stacked in the vertical dimension, each contributing additional light-emitting area. This allows the total light-emitting area to be maintained or increased even as the planar footprint of individual pixels is reduced for higher resolution displays.
Solution Approach 2:
The patent implements a nested structure where multiple epitaxial sub-units are vertically nested within the same pixel footprint. Each sub-unit contains active layers and semiconductor layers that emit light, and they are stacked one above another like nested dolls. This nesting allows multiple light-emitting elements to occupy the same horizontal space while providing cumulative light-emitting area.
3Reliability
If multiple micro-LEDs are mounted individually to achieve full-color display, then color purity may be maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple micro-LED fabrication processes into a single wafer-level operation. Multiple epitaxial sub-units with different color emissions are grown and processed together on the same substrate using sequential epitaxial growth. This combined approach maintains color purity through precise material composition control while dramatically reducing manufacturing complexity by eliminating individual mounting operations.
Solution Approach 2:
The patent performs preliminary fabrication of multiple micro-LED epitaxial sub-units on a common substrate before final device assembly. The semiconductor layers and active layers are pre-formed with precise compositional control for different colors, and preliminary electrical connections are established. This preliminary action allows subsequent simplification of the mounting process while maintaining high color purity standards.
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
The solution increases light emitting area per subpixel, enhances light extraction efficiency, and simplifies manufacturing by stacking epitaxial sub-units on a substrate, achieving high-resolution and full-color display with reduced size and complexity.
Implementation Method 1
a plurality of epitaxial sub-units disposed one over another, each of the epitaxial sub-units configured to emit different colored light
Implementation Method 2
Light emitted from a lower epitaxial sub-unit may be configured to be emitted to the outside of the light emitting stacked structure by passing through an upper epitaxial sub-unit disposed on the lower epitaxial sub-unit
Data Source
AI summary
A display device including a substrate, a light emitting stacked structure disposed on the substrate and including a plurality of epitaxial sub-units disposed one over another, a first adhesive layer bonding the epitaxial sub-units to the substrate; and a line part disposed on the substrate and configured to apply a light emitting signal to each of the epitaxial sub-units, in which the light emitting stacked structure is configured to provide light having various colors by a combination of light emitted from each of the epitaxial sub-units, and the first adhesive layer includes a conductive and non-transparent material.