Multi-Quantum Well Structure for LED Electron Leakage Control
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Solution Overview
Problem
Conventional epitaxial designs for LEDs struggle to alleviate energy-band distortion in the active layer, leading to efficiency droop and increased thickness of the electron-blocking layer, which results in reduced light-emitting efficiency and larger V-pit defects.
Innovation Solution
A multi-quantum well structure is introduced, featuring a stress relief layer, an electron-collecting layer, and an active layer with a first active layer unit comprising alternately stacked potential barrier and well sub-layers, including a GaN/Alx1Iny1Ga(1-x1-y1)N stack in the potential barrier sub-layers to enhance electron blocking and reduce electron leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional epitaxial designs modify the structure and composition of the electron-blocking layer to increase tolerance toward high current density, then the tolerance toward high current density is improved, but the energy-band distortion in the active layer is not alleviated and the thickness of the electron-blocking layer increases resulting in loss of light-emitting efficiency
Solution Approach 1:
The patent introduces a multi-quantum well structure with alternating potential barrier and well sub-layers, where the potential barrier sub-layers have varying Al content (Alx1Iny1Ga(1-x1-y1)N) to create different energy barriers. This parameter variation in composition and structure allows effective electron blocking while maintaining energy band alignment, thereby preventing efficiency droop without increasing the overall layer thickness that would block light emission.
Solution Approach 2:
The patent employs a composite multi-quantum well structure consisting of GaN/Alx1Iny1Ga(1-x1-y1)N stacks with alternating barrier and well layers. This composite structure combines materials with different band gaps and electron affinities to create an optimized electron-blocking mechanism that prevents electron leakage while maintaining transparency to emitted light, thus resolving the contradiction between current density tolerance and light-emitting efficiency.
2Reliability
If the thickness of the electron-blocking layer is increased to prevent electron leakage, then electron blocking capability is improved, but light-emitting efficiency is reduced due to light-blocking effects
Solution Approach 1:
The patent divides the electron-blocking function into multiple thin quantum well layers with alternating potential barriers and wells, rather than using a single thick electron-blocking layer. Each potential barrier sub-layer is thin and strategically positioned to block electrons at specific energy levels while being transparent to photons. This segmented approach achieves effective electron blocking without the light-blocking effects of a thick continuous layer.
3Reliability
If a thick electron-blocking layer with high Al composition is used to fill and flatten the epitaxial layer, then V-pit defects are prevented, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent uses precise control of Al content (x1) and In content (y1) in the Alx1Iny1Ga(1-x1-y1)N potential barrier sub-layers to achieve the desired defect prevention without requiring excessive thickness. By optimizing the composition parameters and layer thicknesses, the patent prevents V-pit defects through proper stress management and lattice matching while maintaining a relatively simple overall structure that is easier to manufacture.
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 proposed multi-quantum well structure effectively alleviates electron leakage and efficiency droop, improving the internal quantum efficiency and light-emitting efficiency of LEDs while reducing the thickness of the electron-blocking layer to minimize light-blocking effects.
Implementation Method 1
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 2
LED device includes a substrate, a buffer layer disposed on the substrate, an N-type cladding layer disposed on the buffer layer, the multi-quantum well structure of the first aspect of the disclosure which is disposed on the N-type cladding layer
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 stack, where 0<x1≤1 and 0≤y1<1. An LED device including the multi-quantum well structure is also disclosed.