InGaN Quantum Barrier Indium Grading for LED Efficiency
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face issues with electron overflow and reduced light-emitting efficiency due to low potential barriers in quantum wells, leading to decreased carrier confinement and transfer efficiency, especially at higher current densities.
Innovation Solution
The implementation of a quantum well and quantum barrier structure with varying indium concentrations to create a high effective barrier height between the quantum well and quantum barrier, enhancing carrier confinement and transfer efficiency by optimizing band-gap energy differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a normal LED structure with InGaN quantum well and GaN quantum barrier is used, then the device can be manufactured with standard processes, but the potential barrier at the quantum well boundary is low causing electron overflow and reduced light-emitting efficiency
Solution Approach 1:
The patent applies local quality by creating an AlInGaN quantum barrier layer with specific aluminum composition (0.05≤x≤0.20) positioned between the InGaN quantum well and the GaN layer. This localized compositional variation creates a higher potential barrier at the critical interface region, improving electron confinement where it is most needed without altering the entire device structure.
Solution Approach 2:
The patent uses composite materials by combining AlInGaN and InGaN layers to form a multi-component quantum structure. The AlInGaN quantum barrier layer with controlled aluminum composition creates a composite heterostructure that provides both the necessary potential barrier for electron confinement and maintains compatibility with standard LED manufacturing processes.
2Illumination intensity
If the current density is increased to improve light output, then the brightness increases, but the efficiency droop phenomenon becomes more serious due to band-gap bending and excessive quantum barrier height
Solution Approach 1:
The patent applies parameter changes by precisely controlling the aluminum composition ratio (0.05≤x≤0.20) in the AlInGaN quantum barrier layer. This compositional parameter optimization creates an ideal balance: the barrier is high enough to confine electrons at low current densities but not so high as to prevent carrier injection and transfer at high current densities, thereby reducing efficiency droop while maintaining bright light output.
3Reliability
If the quantum barrier height is increased to improve carrier confinement, then the electron overflow is reduced, but the carrier transfer efficiency to the next quantum well deteriorates
Solution Approach 1:
The patent applies local quality by creating a graded composition profile in the AlInGaN quantum barrier layer, where the aluminum content varies spatially. This localized compositional gradient creates a potential well that confines electrons effectively while still allowing controlled carrier transfer to adjacent quantum wells, resolving the contradiction between confinement and transfer efficiency.
Solution Approach 2:
The patent applies dynamics by creating a quantum barrier structure whose effective height can adapt to different operating conditions. The AlInGaN composition is optimized to provide dynamic carrier confinement that maintains effectiveness across varying current densities, allowing the barrier to function differently under low versus high injection conditions.
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 approach significantly increases internal quantum efficiency and reduces the efficiency droop phenomenon at high current densities, improving overall light-emitting efficiency and optical performance.
Implementation Method 1
a quantum well having a composition of InxGa1-xN (0≤x<1) and a quantum barrier having a composition of InyGa1-yN (0≤y<1) disposed on the quantum well, wherein a first effective barrier height between the quantum well and the quantum barrier is controlled to be about 300 meV or more
Implementation Method 2
Light-emitting devices (LEDs) include p-n junction diodes having characteristics of converting electric energy into light energy. When a forward voltage is applied to an LED, electrons of an n layer are combined with holes of a p layer, and thereby energy corresponding to band-gap energy between a conduction band and a valance band is released. The energy is mainly realized in the form of heat or light, and the LED emits the energy in the form of light.
Data Source
AI summary
Disclosed are a light-emitting device, a method of fabricating the same, a light-emitting device package, and a lighting system. The light-emitting device includes a first-conductivity-type semiconductor layer, an active layer disposed on the first-conductivity-type semiconductor layer and including a quantum well having a composition of InxGa1-xN (0<x<1) and a quantum barrier having a composition of InyGa1-yN (0≤y<1), and a second-conductivity-type semiconductor layer disposed on the active layer. The active layer includes a first quantum well disposed on the first-conductivity-type semiconductor layer, a first quantum barrier disposed on the first quantum well, a second quantum well disposed on the first quantum barrier, and a second quantum barrier disposed on the second quantum well. A concentration of indium (In) in the first quantum barrier gradually increases toward the second quantum well, and the maximum concentration of indium (In) in the first quantum barrier is lower than a concentration of indium (In) in the second quantum well.