Micro-LED Diode Array Structure for Efficient Transfer and Inspection
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Solution Overview
Problem
Micro-LED displays face challenges in epitaxial chip production, mass transfer, and inspection and repair, including reduced external quantum efficiency due to non-radiative recombination, high costs, and inefficiencies in transferring micro-LEDs, and limited detection and repair capabilities.
Innovation Solution
A diode array with a substrate and light emitting diodes featuring a stack of semiconductor layers, current limiting regions, and electrodes, along with wavelength conversion materials and sealing materials to enhance efficiency and accuracy in mass transfer and inspection, and ion implantation for improved surface flatness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of the LED chip is reduced to enable micro-LED displays, then the display resolution and integration density are improved, but the external quantum efficiency is reduced due to non-radiative recombination at sidewalls and surfaces
Solution Approach 1:
The patent applies local quality by forming a current limiting region with different material composition and electrical properties at the sidewalls compared to the bulk semiconductor layers. This localized modification reduces non-radiative recombination at the critical sidewall surfaces while preserving the light emitting properties of the main active region, thereby resolving the efficiency loss caused by miniaturization.
Solution Approach 2:
The current limiting region is formed as a composite structure combining semiconductor materials with different bandgap energies and carrier transport properties. This composite approach allows the sidewall region to provide both mechanical support and electrical current limitation, reducing surface recombination losses without sacrificing the overall light emitting efficiency of the micro-LED.
2Productivity
If mass transfer technology is used to transfer micro-LEDs onto display substrates, then the production scalability is improved, but the transfer accuracy and device reliability are compromised
Solution Approach 1:
The patent implements preliminary action by pre-forming the current limiting region and electrode structures on the LED chip before the mass transfer process. This pre-configuration ensures that the electrical connections and current distribution pathways are established in advance, maintaining high transfer accuracy and device reliability even when transferring large numbers of micro-LEDs using automated mass transfer technology.
3Reliability
If inspection and repair capabilities are enhanced for micro-LEDs, then the device reliability is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent utilizes color changes by incorporating wavelength conversion materials that emit distinct wavelengths when excited, enabling optical inspection systems to detect the presence, orientation, and electrical functionality of individual micro-LEDs. This optical signaling approach simplifies inspection complexity compared to electrical testing methods, as it allows for non-contact, high-speed detection of device status and defects.
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 emitting efficiency, reduces sidewall leakage current, and facilitates precise and efficient mass transfer and inspection, addressing the limitations of existing micro-LED technologies.
Implementation Method 1
a light emitting layer located between the first semiconductor layer and the second semiconductor layer
Implementation Method 2
ion implantation for improved surface flatness and stability
Data Source
AI summary
A diode array includes a substrate and a plurality of light emitting diodes disposed on the substrate and arranged in an array. Each of the light emitting diodes includes a stack of functional layers includes a first semiconductor layer, a second semiconductor layer, and a light emitting layer located between the first semiconductor layer and the second semiconductor layer. At least one of the light emitting diodes includes a first current limiting region covering at least a portion of the first semiconductor layer, the light emitting layer or the second semiconductor layer; a first electrode electrically connected to the first semiconductor layer; and a second electrode electrically connected to the second semiconductor layer, wherein the first electrode and the second electrode are disposed at the same side of the first semiconductor layer.