Stacked RGB Micro-LED Corner Mesa Contacts for Lower Surface Recombination
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Solution Overview
Problem
Traditional LEDs with mesa structures face issues of reduced internal quantum efficiency due to exposed active layers, surface recombination, and leakage current, leading to structural defects and shortened lifespan, and there is a need for efficient electrical connection of vertically-stacked RGB sub-LEDs to form a single pixel.
Innovation Solution
A vertically-stacked-RGB micro-light-emitting diode with corner mesa contact structures is developed, featuring a substrate with stacked light-emitting structures and tunnel junction layers, where corner mesa contact structures are formed by removing higher layers to expose anode and n-type semiconductor layers, minimizing active layer exposure and facilitating easier manufacturing and electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mesa structure is used for LED manufacturing, then the manufacturing process is established, but the active layers are exposed to the outside causing surface recombination and reduced internal quantum efficiency
Solution Approach 1:
The patent removes the higher layers (p-type semiconductor layer, active layer, and n-type semiconductor layer) at the corner regions to form corner mesa contact structures. This extraction of problematic exposed surfaces eliminates the source of surface recombination while maintaining the essential LED functionality through proper electrical contact formation at the exposed anode and n-type semiconductor layers.
Solution Approach 2:
The patent forms a passivation layer that covers and protects the exposed active layers and side surfaces of the LED structure. This thin film barrier prevents direct exposure of the active layers to the external environment, thereby reducing surface recombination and protecting against plasma damage and contamination during manufacturing processes.
2Reliability
If corner mesa contact structures are formed by removing higher layers, then active layer exposure is minimized, but additional manufacturing steps are required
Solution Approach 1:
The corner mesa contact structures are formed during the semiconductor layer formation process itself, before the final packaging and assembly steps. By preparing the contact structures at the appropriate stage during manufacturing, the patent enables subsequent electrode deposition and electrical connection processes to proceed efficiently without requiring additional complex post-processing steps.
3Illumination intensity
If vertically-stacked RGB sub-LEDs are used to form a single pixel, then color performance is improved, but electrical connection between multiple sub-LEDs becomes complex
Solution Approach 1:
The patent combines multiple RGB sub-LEDs into a vertically-stacked configuration where they share common electrical connections. The corner mesa contact structures enable multiple sub-LEDs to be electrically connected through shared anode and cathode contacts, simplifying the electrical connection architecture compared to lateral arrangements while maintaining superior color performance.
Solution Approach 2:
The corner mesa contact structures serve multiple functions: they provide electrical contact to the anode and n-type semiconductor layers, enable formation of common and individual electrodes, and facilitate vertical stacking of multiple sub-LEDs. This multi-functionality reduces the overall device complexity while achieving efficient electrical connections for RGB display applications.
Data Source
AI summary
The present inventive concept relates to a stacked-RGB micro-light-emitting diode having corner mesa contact structures and a manufacturing method thereof. The stacked-RGB micro-light-emitting diode having corner mesa contact structures includes a first light-emitting structure, a first tunnel junction layer, a first anode layer, a second anode layer, a second tunnel junction layer, a second light-emitting structure, and a third light-emitting structure, which are sequentially stacked on a substrate. According to the present inventive concept, it is possible to increase the lifespan of the micro-light-emitting diode by forming the corner mesa contact structure on each of the light-emitting structures by etching a vertically-stacked structure.