Micro LED Sidewall Structure for Carrier Confinement and Crosstalk
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Solution Overview
Problem
Micro LEDs experience red-shift, lower maximum efficiency, and inhomogeneous emission at high current densities due to fabrication process damage, leading to decreased external and internal quantum efficiencies, as well as nonradiative recombination and electron leakage.
Innovation Solution
A micro LED structure is designed with a first type semiconductor layer, a light emitting layer, and a second type semiconductor layer where at least one part of the sidewall of the second type semiconductor layer is not aligned with the sidewall of the first type semiconductor layer, minimizing carrier spreading and forming a continual quantum well effect to reduce surface carrier loss, and an isolation structure is used between adjacent LEDs to prevent optical and electrical crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the LED pixel size is reduced to achieve higher current densities and better strain relaxation, then the output performance and light extraction efficiency are improved, but fabrication process damage occurs resulting in degraded electrical injection and nonradiative recombination
Solution Approach 1:
The patent applies local quality by creating different structural configurations in different regions of the micro LED. Specifically, the quantum well structure is designed with varying compositions and thicknesses in different zones to optimize carrier confinement and reduce nonradiative recombination at specific locations where fabrication damage occurs, thereby maintaining high electrical injection quality despite small pixel dimensions
Solution Approach 2:
The patent employs parameter changes by systematically varying the composition, thickness, and doping levels of different semiconductor layers in the quantum well structure. These parameter adjustments are made to compensate for fabrication-induced damage and to optimize the balance between achieving high current density operation and maintaining reliable electrical injection, allowing the micro LED to operate effectively at reduced sizes
2Power
If the current density is increased to improve light extraction efficiency, then the output performance is enhanced, but red-shift and inhomogeneous emission occur due to nonradiative recombination
Solution Approach 1:
The patent addresses emission uniformity by implementing local quality variations in the quantum well structure. Different regions of the active layer are designed with tailored compositions and thicknesses to ensure uniform carrier distribution and radiative recombination across the entire micro LED area, preventing inhomogeneous emission even at high current densities
Solution Approach 2:
The patent applies dynamics by designing the quantum well structure to dynamically adapt carrier distribution under high current injection conditions. The structure maintains stable emission characteristics through controlled carrier confinement and transport mechanisms that prevent localized heating and nonradiative recombination, ensuring uniform emission across varying operating conditions
3Stability of the object's composition
If the chip size is reduced to achieve micro LED dimensions, then the strain relaxation is improved, but the peak external quantum efficiency and internal quantum efficiency are largely decreased
Solution Approach 1:
The patent employs parameter changes by systematically optimizing the thickness, composition, and doping levels of each layer in the quantum well structure. These parameter adjustments are specifically designed to maintain high quantum efficiency in miniaturized micro LEDs while preserving the strain relaxation benefits of reduced chip size, achieving a balance between efficiency and dimensional constraints
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
This configuration enhances light emitting efficiency by minimizing surface carrier nonradiative recombination and reducing carrier spreading, while the isolation structure inhibits crosstalk, thereby improving the overall performance of micro LEDs.
Implementation Method 1
a light emitting layer formed on the first type semiconductor layer; and a second type semiconductor layer formed on the light emitting layer
Data Source
AI summary
A micro LED includes a first type semiconductor layer; a light emitting layer formed on the first type semiconductor layer; a second type semiconductor layer formed on the light emitting layer; wherein, at least one part of a sidewall of the second type semiconductor layer is not aligned with a sidewall of the first type semiconductor layer.