AlInGaN Strain Relief Layer for LED Light Efficiency
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Solution Overview
Problem
Conventional nitride semiconductor LEDs face challenges in maximizing light efficiency and minimizing operating voltage due to light absorption by strain relief layers and voltage loss, respectively, as the lattice matching effect leads to bandgap energy approximation between the strain relief layer and the active layer.
Innovation Solution
Incorporating an AlxInyGa1-x-yN layer with a multi-layer structure, where the lattice constant is greater than the first conductive semiconductor layer and smaller than the active layer, to maintain a predetermined bandgap energy difference and reduce strain, thereby minimizing light absorption and voltage loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lattice constant of the strain relief layer is increased to match the active layer, then strain relief effect is improved, but light absorption by the strain relief layer increases
Solution Approach 1:
The patent changes the lattice constant parameter of the strain relief layer by using an AlInGaN alloy with specific composition ratios, where the lattice constant is deliberately set to be smaller than that of the active layer (InGaN) but greater than the first conductive semiconductor layer. This parameter optimization allows strain relief while maintaining bandgap energy difference to prevent light absorption.
Solution Approach 2:
The patent employs a composite material structure where the strain relief layer is formed by AlInGaN alloy combining aluminum, indium, and gallium nitride. This composite approach enables independent control of lattice constant and bandgap energy through compositional adjustment, resolving the contradiction between strain relief and light absorption.
2Reliability
If the thickness of the strain relief layer is increased to sufficiently relieve strain, then strain relief is improved, but operating voltage increases due to voltage loss
Solution Approach 1:
The patent optimizes the thickness parameter of the strain relief layer to a specific range that provides sufficient strain relief while minimizing voltage loss. Additionally, the band discontinuity parameter is reduced through compositional optimization of the AlInGaN layer, further decreasing operating voltage.
3Manufacturing precision
If the bandgap energy of the strain relief layer is reduced to match the active layer, then lattice matching is improved, but light absorption increases
Solution Approach 1:
The patent independently optimizes two critical parameters: the lattice constant is adjusted through AlInGaN composition to achieve lattice matching with the active layer, while the bandgap energy is controlled to maintain a predetermined difference. This dual-parameter optimization resolves the contradiction between lattice matching and light absorption prevention.
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 enhances light efficiency by reducing light absorption in the strain relief layer and lowers the operating voltage by minimizing band discontinuity, resulting in improved performance of the light emitting device.
Implementation Method 1
the lattice constant of the AlxInyGa1-x-yN layer has a greater value than the lattice constant of the first conductive semiconductor layer and a smaller value than the lattice constant of the active layer
Implementation Method 2
the bandgap energy difference from the active layer is maintained to a predetermined value or more to minimize the absorption of the emitted light in the AlxInyGa1-x-yN layer
Implementation Method 3
A light emitting device (LED) includes a p-n junction diode having a characteristic of converting electric energy into light energy. When forward voltage is applied to the LED, electrons of an n layer are combined with holes of a p layer, so that energy corresponding to an energy gap between a conduction band and a valance band may be generated. This energy is realized as heat or light, and the LED emits the energy in the form of light.
Data Source
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AI summary
Disclosed are a light emitting device, a method of fabricating the light emitting device, a light emitting device package, and a lighting system. The light emitting device includes a first conductive semiconductor layer, an AlxInyGa1 -x- yN layer (0＜x=1 and 0＜y=1) on the first conductive semiconductor layer, an active layer on the AlxInyGa1 -x- yN layer, and a second conductive semiconductor layer on the active layer.