Micro-LED Quantum Well Segmentation for Sidewall Recombination Loss
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Solution Overview
Problem
Micro-LEDs face efficiency losses due to non-radiative recombination at the sidewalls of the LED mesa, which is exacerbated by the high surface-to-volume ratio, leading to reduced internal and external quantum efficiency.
Innovation Solution
The active region of the LED is divided into a matrix of quantum well (QW) structures, which are quantum mechanically isolated by a quantum barrier (QB) layer. This QB layer surrounds each QW structure, reducing non-radiative recombination and plasmonic absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the physical size of LEDs is reduced to create micro-LEDs, then device miniaturization and integration density are improved, but non-radiative recombination at sidewalls increases due to high surface-to-volume ratio
Solution Approach 1:
The active region is divided into multiple isolated quantum well structures separated by quantum barrier layers. This segmentation creates discrete light-emitting regions that are electrically and optically isolated from each other, preventing carrier migration to sidewalls and reducing non-radiative recombination losses in miniaturized LEDs
Solution Approach 2:
Quantum barrier layers are introduced as intermediary structures between adjacent quantum wells. These barrier layers act as potential walls that confine charge carriers within individual quantum well regions, preventing their migration to the sidewalls where non-radiative recombination occurs, thus preserving light emission efficiency in small-scale devices
2Length of moving object
If the physical size of LEDs is reduced, then device miniaturization is improved, but internal quantum efficiency decreases due to increased surface recombination
Solution Approach 1:
The active region is divided into multiple isolated quantum well structures separated by quantum barrier layers. This segmentation creates discrete light-emitting regions that are electrically and optically isolated from each other, preventing carrier migration to sidewalls and reducing non-radiative recombination losses in miniaturized LEDs
Solution Approach 2:
Different regions of the LED structure are given different properties: quantum wells are designed for light emission while quantum barrier layers are designed for carrier confinement. This local differentiation ensures that carrier injection and recombination occur primarily in the quantum well regions rather than at the sidewalls, maintaining high internal quantum efficiency in micro-LEDs
3Length of moving object
If the physical size of LEDs is reduced, then device miniaturization is improved, but external quantum efficiency decreases due to increased surface recombination
Solution Approach 1:
The active region is divided into multiple isolated quantum well structures separated by quantum barrier layers. This segmentation creates discrete light-emitting regions that are electrically and optically isolated from each other, preventing carrier migration to sidewalls and reducing non-radiative recombination losses in miniaturized LEDs
Solution Approach 2:
Quantum barrier layers are introduced as intermediary structures between adjacent quantum wells. These barrier layers act as potential walls that confine charge carriers within individual quantum well regions, preventing their migration to the sidewalls where non-radiative recombination occurs, thus preserving light emission efficiency in small-scale devices
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
The approach significantly reduces non-radiative recombination, leading to improved internal and external quantum efficiency, and enhances light extraction by minimizing surface defects and recombination at the mesa sidewalls.
Implementation Method 1
The QW structures are quantum mechanically isolated from each other, in large part due to nanostructures (e.g., ridges) formed in a quantum barrier (QB) layer
Implementation Method 2
Charge carriers (electrons and holes) may be confined and recombine in the QW(s) to release energy in the form of photons, i.e., light
Implementation Method 3
non-radiative recombination of charge carriers at and/or near the sidewalls of an LED mesa is a major contributor to reduced internal quantum efficiency (IQE) and reduced external quantum efficiency (EQE)
Data Source
AI summary
LED devices and corresponding techniques for manufacturing LED devices are described. In some embodiments, an LED device includes a plurality of mesas, each mesa corresponding to a separate LED and including a layered semiconductor structure. The layered semiconductor structure includes an active region and a quantum barrier (QB) layer. The active region has a matrix of quantum well (QW) cells that are quantum mechanically isolated by the QB layer. In particular, the QB layer can include ridge-shaped structures that laterally separate adjacent QW cells. The matrix of QW cells can be arranged as a two-dimensional array. In some embodiments, the QW cells are epitaxially grown such that each QW cell is thicker along a central region and thinner along a peripheral region, with the peripheral region corresponding to where the QW cell meets a ridge-shaped structure of the QB layer.