Nitride Light Emitting Device Strain Relief Insertion Layers
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Solution Overview
Problem
GaN-based light emitting diodes face challenges due to strain and imperfections caused by lattice constant differences in semiconductor layers, leading to reduced light emitting efficiency and reliability.
Innovation Solution
Incorporating first and second insertion layers with specific energy band gaps and compositions between conductive semiconductor layers and the active layer to relieve strain and enhance electron-hole confinement, thereby improving the structural integrity and optical efficiency of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GaN-based semiconductor layers are grown on heterogeneous substrates, then it is possible to fabricate LEDs with wide band gap and high thermal stability, but strain and dislocations occur due to lattice constant differences, reducing light emitting efficiency and reliability
Solution Approach 1:
The patent introduces insertion layers composed of multiple quantum wells between the active layer and barrier layers. These insertion layers act as intermediaries that gradually transition the lattice constant between layers with different compositions, thereby reducing strain and dislocation formation while maintaining the benefits of lattice mismatch for carrier confinement.
Solution Approach 2:
The patent varies the composition parameters of the insertion layers by controlling the indium content in the multiple quantum well structure. By adjusting the indium composition gradient across the insertion layers, the lattice constant is progressively changed to match between adjacent layers, effectively managing strain without sacrificing the quantum confinement effect.
2Stability of the object's composition
If insertion layers are added to relieve strain, then structural integrity is improved, but device complexity increases due to additional layers
Solution Approach 1:
The patent divides the insertion layer into multiple thin quantum well layers with different indium compositions rather than using a single thick layer. This segmentation allows for gradual lattice constant transition while maintaining precise control over each layer's properties, achieving strain relief without excessive complexity.
Solution Approach 2:
The patent creates a composite structure combining multiple quantum wells with different indium compositions within the insertion layer. This composite approach enables the layer to simultaneously provide strain management through composition gradient and carrier confinement through quantum well effects, achieving multiple functions in a unified structure.
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 insertion layers effectively reduce strain, improve carrier confinement, and enhance the reliability and efficiency of the light emitting device, leading to increased brightness and lifespan, as well as better electro-static discharge properties.
Implementation Method 1
at least one first insertion layer located in at least one of a boundary between the first conductive semiconductor layer and the active layer and a boundary between the second conductive semiconductor layer and the active layer, the first insertion layer having an energy band gap between a barrier layer and a well layer of the active layer
Implementation Method 2
GaN and InGaN have a large difference between their lattice constants. Therefore, with such a large difference between the lattice constants of the well 21 and the barrier 22, the active layer 20 must be affected by a serious strain that causes imperfections in solids
Data Source
AI summary
A nitride based light emitting device is disclosed. More particularly, a nitride based light emitting device capable of improving light emitting efficiency and reliability thereof is disclosed. The nitride based light emitting device includes a first conductive semiconductor layer connected to a first electrode, a second conductive semiconductor layer connected to a second electrode, an active layer located between the first conductive semiconductor layer and the second conductive semiconductor layer and having a quantum well structure, a first insertion layer located in at least one of a boundary between the first conductive semiconductor layer and the active layer and a boundary between the second conductive semiconductor layer and the active layer, and a second insertion layer located adjacent to the first insertion.