Vertical Micro-LED Structure With Backplane Current Control
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Solution Overview
Problem
The reduction in size of optoelectronic devices, such as LEDs, leads to performance issues like higher leakage current, charge crowding, charge imbalance, and unwanted recombination, which affect the efficiency and uniformity of the devices.
Innovation Solution
The development of an optoelectronic device with a monolithic active layer and a common top electrode, integrated with a backplane driving circuit, which manipulates the lateral conduction to control current flow and reduce defects, thereby enhancing device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of optoelectronic devices is reduced to create higher pixel density, then pixel density increases, but device performance deteriorates due to higher leakage current, charge crowding, charge imbalance, and unwanted recombination
Solution Approach 1:
The device layer is divided into multiple independently controllable micro devices arranged in an array, with each device having its own bottom contact and being addressable through the driving circuit. This segmentation allows individual control and compensation of performance issues in each micro device while maintaining high overall pixel density
Solution Approach 2:
The driving circuit provides localized current control to each micro device through individual bottom contacts and pads, enabling independent adjustment of electrical characteristics for each device. This local control allows compensation for charge crowding and imbalance specific to each micro device region
2Quantity of substance
If the size of optoelectronic devices is reduced, then pixel density increases, but leakage current increases due to defects
Solution Approach 1:
The driving circuit acts as an intermediary between the power source and the micro devices, controlling and regulating the current flow to each individual device. This intermediary control prevents excessive current that could cause leakage and allows for optimized operating conditions that minimize defect-related leakage current
3Quantity of substance
If the size of optoelectronic devices is reduced, then pixel density increases, but charge crowding and charge imbalance occur at interfaces
Solution Approach 1:
Each micro device is equipped with individual bottom contacts and is addressable through dedicated pads in the driving circuit, enabling localized control of charge distribution. This local control allows independent adjustment of electrical characteristics for each device region, preventing charge crowding and imbalance at interfaces
Solution Approach 2:
The driving circuit provides dynamic control of current flow to each micro device, allowing real-time adjustment of electrical conditions to maintain charge balance. This dynamic control compensates for charge crowding effects that occur during operation, especially in reduced-size high-density configurations
Data Source
AI summary
As the pixel density of optoelectronic devices becomes higher, and the size of the optoelectronic devices becomes smaller, the problem of isolating the individual micro devices becomes more difficult. A method of fabricating an optoelectronic device, which includes an array of micro devices, comprises: forming a device layer structure including a monolithic active layer on a substrate; forming an array of first contacts on the device layer structure defining the array of micro devices; mounting the array of first contacts to a backplane comprising a driving circuit which controls the current flowing into the array of micro devices; removing the substrate; and forming an array of second contacts corresponding to the array of first contacts with a barrier between each second contact.