GaN-Interlayer Quantum Wells for High-Efficiency UV Micro-LEDs
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Solution Overview
Problem
Conventional UV light-emitting diodes (LEDs) face challenges in achieving high internal quantum efficiency and crystal quality, particularly in micro-LEDs with dimensions below 100 μm, due to limitations in carrier recombination efficiency and light extraction efficiency.
Innovation Solution
The use of a quantum well structure with an InGaN/GaN/AlGaN heterostructure design, incorporating a GaN interlayer between InGaN or AlInGaN well layers and AlGaN barrier layers, enhances electron and hole wave function overlap and improves crystal quality, leading to increased carrier recombination efficiency and internal quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional InGaN/AlGaN quantum well structure is used, then device structure is simple, but internal quantum efficiency and carrier recombination efficiency are limited
Solution Approach 1:
The quantum well structure is segmented into multiple periods, each containing InGaN well layers, GaN interlayers, and AlGaN barrier layers. This segmentation creates discrete carrier recombination regions that improve internal quantum efficiency by confining carriers more effectively in each period, resolving the contradiction between structural simplicity and efficiency.
Solution Approach 2:
GaN interlayers are introduced as intermediary layers between the InGaN well layers and AlGaN barrier layers. These interlayers mediate the transition between different material compositions, reducing lattice mismatch and dislocation density, thereby improving crystal quality and carrier recombination efficiency without significantly complicating the overall structure.
2Power
If micro-LED dimensions are reduced below 100 μm, then light extraction efficiency and output power increase, but carrier recombination efficiency deteriorates
Solution Approach 1:
The patent applies local quality by creating regions with different compositions and properties within the quantum well structure. The InGaN well layers provide strong carrier confinement, while the GaN interlayers and AlGaN barrier layers provide graded composition transitions. This local optimization of material properties maintains high carrier recombination efficiency even in miniaturized devices with dimensions below 100 μm.
Solution Approach 2:
The patent utilizes parameter changes by varying the composition ratios (x, y, z values) of InGaN, AlInGaN, and AlGaN layers, as well as adjusting layer thicknesses and growth temperatures. These parameter optimizations enable the quantum well structure to maintain high carrier recombination efficiency across different device sizes, resolving the contradiction between miniaturization and recombination efficiency.
3Reliability
If GaN interlayer is added to the quantum well, then carrier recombination efficiency and internal quantum efficiency improve, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the GaN interlayer structure. The interlayers simultaneously provide lattice matching, reduce dislocation density, confine carriers, and facilitate efficient recombination. By combining these multiple functions into a single structural element, the patent improves carrier recombination efficiency without proportionally increasing device complexity.
Solution Approach 2:
The quantum well structure employs composite materials consisting of InGaN, GaN, and AlGaN layers with different compositions and properties. This composite structure leverages the advantages of each material: InGaN for strong carrier confinement and light emission, GaN for lattice matching and low dislocation density, and AlGaN for barrier formation. The composite design improves overall device performance while maintaining reasonable structural complexity.
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 design results in improved light-emitting device performance, with enhanced internal quantum efficiency and crystal quality, particularly in micro-LEDs, by creating a double well structure that increases carrier recombination efficiency and reduces the quantum confined Stark effect.
Implementation Method 1
one or more quantum wells formed by one or more repeating periods of a heterostructure comprising: a well layer comprising InGaN, an interlayer comprising GaN disposed on the well layer, and a barrier layer comprising AlGaN
Implementation Method 2
depositing an interlayer comprising GaN on the well layer, wherein the interlayer is deposited via metal organic chemical vapor deposition from two or more metal organic precursor molecules and one or more nitrogen-containing precursor molecules
Data Source
AI summary
Group III-nitride-based light-emitting devices are provided. The light-emitting devices are characterized by an active region having one or more quantum wells. The one or more quantum wells having a double well design provided by a first well layer comprising an AlInGaN alloy or an InGaN alloy and an adjacent GaN interlayer, both of which are disposed between two barrier layers comprising an AlGaN alloy or a low-In-content AlInGaN alloy.