Micro LED Sidewall Structure for Uniform High-Current Emission
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Solution Overview
Problem
Micro LEDs with higher current densities experience red-shift, lower maximum efficiency, and inhomogeneous emission due to fabrication process damage, leading to decreased external and internal quantum efficiencies caused by nonradiative recombination and poor current injection.
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 the sidewall of the second type semiconductor layer is not aligned with a straight line, minimizing carrier spreading and forming a continual quantum well effect to reduce surface carrier nonradiative recombination, and an isolation structure is used between adjacent LEDs to prevent optical and electrical crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If micro LED pixel size is reduced to increase current density, then output performance and light extraction efficiency are improved, but red-shift, lower maximum efficiency, and inhomogeneous emission occur due to fabrication damage
Solution Approach 1:
The patent applies local quality by creating a non-uniform sidewall profile in the second type semiconductor layer, where the width varies along the height. This local geometric variation optimizes the electric field distribution and current spreading specifically at the sidewall region, addressing the emission uniformity problem without requiring overall pixel size changes.
Solution Approach 2:
The patent introduces curvature by designing the sidewall of the second type semiconductor layer to be non-linear (convex or concave) rather than straight. This curved profile modifies carrier transport paths and reduces edge effects, thereby improving emission uniformity and reducing red-shift while maintaining high current density operation.
2Illumination intensity
If micro LED pixel size is reduced, then light extraction efficiency is improved, but external quantum efficiency decreases due to nonradiative recombination from etching damage
Solution Approach 1:
The patent changes the geometric parameter of the second type semiconductor layer by introducing a non-linear sidewall profile. This parameter modification optimizes the balance between light extraction efficiency and nonradiative recombination losses, improving external quantum efficiency without sacrificing light extraction performance.
3Power
If micro LED pixel size is reduced, then current density increases, but internal quantum efficiency decreases due to poor current injection and electron leakage
Solution Approach 1:
The patent applies local quality by creating a non-uniform sidewall profile in the second type semiconductor layer, where the width varies along the height. This local geometric variation optimizes the electric field distribution and current spreading specifically at the sidewall region, addressing the emission uniformity problem without requiring overall pixel size changes.
Solution Approach 2:
The patent introduces curvature by designing the sidewall of the second type semiconductor layer to be non-linear (convex or concave) rather than straight. This curved profile modifies carrier transport paths and reduces edge effects, thereby improving emission uniformity and reducing red-shift while maintaining high current density operation.
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 structure minimizes surface carrier loss, optimizes quantum well sidewall area, and improves light emitting efficiency by preventing carrier spreading and crosstalk, thereby enhancing 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; and a second type semiconductor layer formed on the light emitting layer; wherein a bottom sidewall of the second type semiconductor layer is aligned with a sidewall of the first type semiconductor layer; and a sidewall of the second type semiconductor layer does not conform a straight line.