Vertical Micro-LED Pillar Arrays for Leakage and Recombination Control
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Solution Overview
Problem
The reduction in size of optoelectronic devices, such as LEDs, to achieve higher pixel density leads to performance issues like increased leakage current, charge crowding, and unwanted recombination, which affect the efficiency and uniformity of the devices.
Innovation Solution
The development of vertical solid-state devices with a pillar layer patterned into an array of pillars, bonded to a pad substrate with a driving circuit, and a method of fabricating optoelectronic devices by forming a device layer structure with active and conductive layers, and modifying the lateral conduction to control current flow and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of optoelectronic devices is reduced to achieve higher pixel density, then the pixel density increases, but leakage current increases and device performance deteriorates
Solution Approach 1:
The device layer structure is divided into multiple discrete pillars arranged in an array, with each pillar representing an individual optoelectronic device. This segmentation isolates current flow paths between devices, preventing leakage current from affecting adjacent pixels while maintaining high device density on the substrate.
Solution Approach 2:
The pillar layer is formed with specific local structural characteristics including controlled height, diameter, and material composition. Each pillar exhibits optimized local electrical properties through selective doping and material deposition, ensuring uniform current distribution and reduced leakage at device interfaces while maintaining high pixel density.
2Productivity
If the size of optoelectronic devices is reduced, then pixel density increases, but charge crowding and unwanted recombination increase
Solution Approach 1:
The device layer is segmented into discrete pillars with isolated active regions, confining charge carriers within each pillar's active layer. This segmentation prevents charge crowding at interfaces between adjacent devices and reduces non-radiative recombination pathways, maintaining high internal quantum efficiency at high pixel densities.
Solution Approach 2:
The conductive layers between the active layers and substrate serve as intermediaries that facilitate controlled charge transport. These conductive layers are engineered with specific carrier concentrations and mobility characteristics to efficiently extract charges from the active region while minimizing recombination losses, enabling high efficiency at reduced device sizes.
Data Source
AI summary
An optoelectronic device comprising a pad substrate comprising an array of pads connected to a driving circuit; and a device layer structure deposited on a substrate, wherein the device layer structure including a plurality of active layers and conductive layers; and a pillar layer formed on or part of a first conductive layer, wherein the pillar layer is patterned into array of pillars to create pixelated micro devices and wherein the array of pillars is bonded to the array of pads. The redundant pillars that are not bonded to the array of pads may be provided a fixed voltage or used as sensors.