Vertical LED With Color Conversion Electrode for Micro-LED Displays
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Solution Overview
Problem
Conventional blue, green, and red LED chips with lateral or flip-chip structures face limitations in miniaturization and light extraction efficiency due to reduced active light-emitting areas and scattering issues with sapphire substrates, making them unsuitable for micro-LED displays.
Innovation Solution
A vertical type light emitting element with a color conversion electrode part that combines the functions of an electrode and color converter, featuring a light transmissive plate and a color conversion layer on a roughened surface of the light emitting semiconductor part, enhancing light extraction and color conversion efficiency while maintaining high color uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional lateral or flip-chip LED chip structures are used, then the chip can be fabricated with standard processes, but the active light-emitting area is reduced due to mesa etching, limiting miniaturization and light extraction efficiency
Solution Approach 1:
The patent inverts the conventional LED chip structure by adopting a vertical configuration where the light-emitting layer is positioned at the bottom and light extracts upward through the substrate, rather than the conventional lateral or flip-chip structures where light extracts sideways or from the top surface. This inversion eliminates the need for mesa etching that reduces active area, allowing the entire chip area to be utilized for light emission while improving light extraction efficiency
Solution Approach 2:
The patent transitions from two-dimensional lateral light extraction in conventional chips to three-dimensional vertical light extraction by removing the sapphire substrate and forming a reflective electrode part at the bottom, allowing light to extract in the vertical dimension. This dimensional change increases the effective light-emitting area and improves light extraction efficiency without compromising manufacturability
2Reliability
If a sapphire substrate is used in flip-chip LED chips, then the chip structure is stable, but light scattering occurs due to substrate thickness, reducing light extraction efficiency
Solution Approach 1:
The patent extracts and removes the sapphire substrate from the LED chip structure entirely, eliminating the source of light scattering caused by substrate thickness. By removing this problematic component, the invention achieves superior light extraction efficiency while maintaining structural stability through alternative support and reflective electrode designs
Solution Approach 2:
The patent converts the harmful effect of the sapphire substrate (light scattering) into a benefit by replacing it with a reflective electrode part that actively enhances light extraction. The reflective electrode part not only eliminates the scattering problem but also improves light extraction efficiency by reflecting light that would otherwise be lost back into the light-emitting layer
3Ease of manufacture
If color conversion layer is formed on sapphire substrate, then color conversion is achieved, but color uniformity varies between regions with and without active layer
Solution Approach 1:
The patent creates a color conversion electrode part that performs multiple functions simultaneously: it serves as both an electrical electrode and a color conversion layer. This multi-functional design ensures uniform color conversion across the entire chip area, including regions where the active layer is not present, eliminating the color uniformity issues observed in conventional structures
Solution Approach 2:
The patent merges the electrode function and color conversion function into a single integrated color conversion electrode part. By combining these two separate functions into one component, the invention achieves consistent color conversion across all regions of the chip while maintaining electrical connectivity, thereby improving both manufacturing simplicity and color uniformity
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 improves light extraction efficiency and color uniformity by forming a color conversion electrode part on the roughened surface of the light emitting semiconductor part, allowing for increased light entry and efficient conversion, suitable for high-resolution micro-LED displays.
Implementation Method 1
roughnesses are formed on the upper surface of the light emitting semiconductor part to increase the amount of light entering the color conversion electrode part through the light emitting semiconductor part
Implementation Method 2
roughnesses are formed on the upper surface of the light emitting semiconductor part to increase the amount of light entering the color conversion electrode part through the light emitting semiconductor part
Implementation Method 3
a color conversion layer which converts a wavelength of light into another wavelength
Data Source
AI summary
A vertical type light emitting element is disclosed. The vertical type light emitting element includes: a color conversion electrode part including a first electrode pad and a color conversion layer; a reflective electrode part including a second electrode pad and a reflective layer; and a light emitting semiconductor part interposed between the color conversion electrode part and the reflective electrode part. The color conversion electrode part further includes an electrically conductive light transmissive plate. The first electrode pad and the color conversion layer are interposed between the light transmissive plate and the upper surface of the light emitting semiconductor part. Roughnesses are formed on the upper surface of the light emitting semiconductor part bordering the color conversion electrode part to increase the amount of light entering the color conversion electrode part through the light emitting semiconductor part.