Infrared Light Emitting Device Dislocation Filter Layer
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Solution Overview
Problem
Infrared light emitting devices face challenges in achieving sufficient light emission intensity due to high defect densities in the light emitting layer, primarily caused by line defects resulting from lattice constant differences between the semiconductor substrate and the compound semiconductor material, which are not effectively addressed by increasing film thickness.
Innovation Solution
The implementation of a dislocation filter layer with specific thickness and composition, such as Aly(1)In1−y(1)Sb, to reduce dislocation density by bending and suppressing the propagation of dislocations, thereby improving the light emission intensity by reducing non-radiative recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the film thickness of the light emitting layer is increased to improve light emission intensity, then the light emission intensity is improved, but the defect density increases due to lattice constant differences causing dislocation propagation
Solution Approach 1:
An intermediate layer with composition Alx(1)In(1-x)Sb is introduced between the semiconductor substrate and the light emitting layer. This intermediate layer acts as a mediator that gradually transitions the lattice constant from the substrate to the light emitting layer, reducing lattice mismatch and suppressing dislocation propagation, thereby enabling thicker light emitting layers with lower defect densities
Solution Approach 2:
The patent applies local quality by creating a composition gradient within the intermediate layer, where the Al composition varies spatially to provide different lattice matching characteristics at different depths. This localized composition adjustment optimizes the lattice constant transition at each interface, effectively reducing dislocation density while allowing increased light emitting layer thickness
2Illumination intensity
If a dislocation filter layer is added to reduce dislocation density, then the light emission intensity is improved by reducing non-radiative recombination, but the device complexity and manufacturing process complexity increase
Solution Approach 1:
The intermediate layer Alx(1)In(1-x)Sb serves multiple functions simultaneously: it acts as a lattice constant transition layer to reduce mismatch, functions as a dislocation filter to suppress propagation, and provides a compositional gradient for stress management. This multi-functionality reduces the need for separate dedicated layers, thereby limiting the increase in device complexity while achieving improved light emission intensity
3Reliability
If the Al composition in the intermediate layer is optimized to reduce lattice mismatch, then the dislocation density is reduced, but the manufacturing precision requirements increase due to specific composition and thickness constraints
Solution Approach 1:
The patent defines specific parameter ranges for the intermediate layer, including Al composition x(1) between 0.01 and 0.20 and thickness tx(1) between 50 nm and 500 nm. These parameter specifications provide a controlled optimization window that balances dislocation reduction with manufacturability, allowing sufficient tolerance for standard fabrication processes while achieving the desired defect density reduction
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 use of a dislocation filter layer effectively reduces line defect density and enhances light emission intensity, as demonstrated by achieving light emission intensities up to 2.7 times higher than comparative examples, while maintaining a relatively small increase in film formation time and process complexity.
Implementation Method 1
reduce dislocation density by bending and suppressing the propagation of dislocations
Implementation Method 2
improving the light emission intensity by reducing non-radiative recombination
Data Source
AI summary
Disclosed is an infrared light emitting device including: a semiconductor substrate; a first layer formed on the semiconductor substrate and having a first conductivity type; a light emitting layer formed on the first layer; and a second layer formed on the light emitting layer and having a second conductivity type, wherein the first layer includes, in the stated order: a layer containing Alx(1)In1−x(1)Sb; a layer having a film thickness ty(1) in nanometers and containing Aly(1)In1−y(1)Sb; and a layer containing Alx(2)In1−x(2)Sb, where ty(1), x(1), x(2), and y(1) satisfy the following relations: for j=1, 2, 0<ty(1)≤2360×(y(1)−x(j))−240 (0.11≤y(1)−x(j)≤0.19), 0<ty(1)≤−1215×(y(1)−x(j))+427 (0.19<y(1)−x(j)≤0.33), and 0<x(j)<0.18.