Multi-Quantum Well LED Structure for Efficiency Droop
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional epitaxial designs for LED devices fail to adequately address energy-band distortion and efficiency droop issues under high current density, often resulting in reduced light-emitting efficiency and increased defect openings due to thick electron-blocking layers.
Innovation Solution
A multi-quantum well structure with a stress relief layer, an electron-collecting layer, and an active layer featuring alternately stacked potential barrier and well sub-layers, including a GaN/AlxInyGa(1-x-y)N/GaN stack, which enhances electron blocking and reduces electron leakage, while maintaining a thinner electron-blocking layer to improve lattice quality and prevent dopant permeation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the electron-blocking layer is increased to improve electron blocking capability, then electron leakage is reduced, but light-emitting efficiency is lost and defect openings are enlarged
Solution Approach 1:
The electron-blocking layer is segmented into multiple thin alternating layers of AlGaN and GaN materials, forming a superlattice structure. This segmentation allows each thin layer to contribute to electron blocking while the overall structure remains thin enough to maintain light-emitting efficiency and prevent defect openings, resolving the contradiction between electron blocking capability and light-emitting efficiency.
2Reliability
If the Al content in the electron-blocking layer is increased to improve electron blocking, then electron leakage is reduced, but the thickness of the layer increases causing light-emitting efficiency loss
Solution Approach 1:
The electron-blocking layer employs alternating layers with different Al contents - the AlGaN layers provide high electron blocking capability locally, while the GaN layers provide lower resistance paths. This local quality variation allows the structure to achieve effective electron blocking without increasing the overall thickness, maintaining light-emitting efficiency while preventing electron leakage.
3Reliability
If a thick electron-blocking layer with high Al composition is used to prevent electrostatic discharge, then electrostatic discharge protection is improved, but V-pit defect openings are enlarged requiring thicker P-type cladding layer
Solution Approach 1:
The electron-blocking layer is divided into multiple thin alternating layers of AlGaN and GaN. This segmentation provides distributed electrostatic discharge protection throughout the structure while keeping each layer thin enough to prevent V-pit defect openings, thereby avoiding the need for thicker P-type cladding layers and reducing overall device 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
The multi-quantum well structure effectively alleviates electron leakage and efficiency droop, enhancing the internal quantum efficiency and light-emitting efficiency of LED devices while maintaining competitiveness through improved lattice quality and reduced defect openings.
Implementation Method 1
Such conventional epitaxial designs may not alleviate the energy-band distortion in the active layer of the LED device
Implementation Method 2
an active layer including a first active layer unit that is disposed on the electron-collecting layer. The first active layer unit includes a plurality of potential barrier sub-layers and a plurality of potential well sub-layers being alternately stacked
Implementation Method 3
forming the electron-blocking layer with a superlattice structure such as an AlGaN/GaN superlattice structure, an AlN/GaN superlattice structure, and an AlN/AlGaN superlattice structure
Data Source
AI summary
Disclosed is a multi-quantum well structure including a stress relief layer, an electron-collecting layer disposed on the stress relief layer, and an active layer including a first active layer unit that is disposed on the electron-collecting layer. The first active layer unit includes potential barrier sub-layers and potential well sub-layers being alternately stacked, in which at least one of the potential barrier sub-layers has a GaN/Alx1Iny1Ga(1-x1-y1)N/GaN stack, where 0<x1≤1 and 0≤y1<1, and for the remainder of the potential barrier sub-layers, each of the potential barrier sub-layers is a GaN layer. An LED device including the multi-quantum well structure is also disclosed.