Superlattice Defect Barrier for Lattice-Mismatched Semiconductor Layers
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Solution Overview
Problem
Traditional semiconductor devices using GaAs or InP substrates face serious lattice mismatch issues with light-absorbing layers, leading to defects and increased dark current due to the use of metamorphic buffer layers, which disrupt the lattice and propagate defects to the light-absorbing or cladding layers.
Innovation Solution
A semiconductor device is designed with a defect blocking region featuring a superlattice structure that includes alternating layers with strain relative to the semiconductor layer, or with lattice constants close to or equal to the semiconductor layer, to prevent defect propagation from the metamorphic buffer or defect source region, thereby reducing defects and dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a metamorphic buffer layer is used to bridge lattice mismatch between substrate and light-absorbing layer, then the lattice continuity is improved, but serious defects are generated and propagated to the light-absorbing layer
Solution Approach 1:
The buffer layer is segmented into multiple sections: a first buffer layer directly on the substrate, a second buffer layer on the first buffer layer, and a defect blocking region between them. This segmentation allows each section to serve different functions - the first buffer layer addresses lattice mismatch with the substrate, while the defect blocking region prevents defect propagation to the light-absorbing layer, thus maintaining lattice continuity without propagating defects.
Solution Approach 2:
The defect blocking region acts as an intermediary layer between the metamorphic buffer layer and the light-absorbing layer. This intermediary structure has a lattice constant closer to that of the light-absorbing layer, serving as a transition that blocks defect propagation while maintaining overall lattice continuity across the heterostructure.
2Ease of manufacture
If a metamorphic buffer layer is used to accommodate lattice mismatch, then the epitaxial growth is enabled, but dark current increases due to defect propagation
Solution Approach 1:
The buffer structure is divided into functional segments where the first buffer layer enables epitaxial growth by accommodating lattice mismatch, while the defect blocking region segment prevents defect propagation that would otherwise increase dark current. This segmentation allows simultaneous achievement of manufacturability and low dark current.
Solution Approach 2:
The defect blocking region serves as an intermediary that blocks the propagation of defects from the metamorphic buffer layer to the light-absorbing layer, thereby preventing the increase in dark current while still allowing epitaxial growth to proceed through the buffer layers.
3Manufacturing precision
If the lattice constant of the buffer layer matches the substrate, then the substrate interface is optimized, but defects propagate to the light-absorbing layer
Solution Approach 1:
The buffer structure is segmented into a first buffer layer with lattice constant matching the substrate (optimizing substrate interface) and a defect blocking region with lattice constant closer to the light-absorbing layer (preventing defect propagation). This segmentation allows both interface quality and light-absorbing layer quality to be optimized simultaneously.
Solution Approach 2:
Different regions of the buffer structure have different lattice constants optimized for their local functions: the first buffer layer has lattice constant optimized for substrate interface, while the defect blocking region has lattice constant optimized for preventing defect propagation to the light-absorbing layer. This local quality variation resolves the contradiction between interface quality and layer quality.
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 implementation of a superlattice defect blocking region significantly reduces defects and dark current in the semiconductor layer, improving the quality of the epitaxial structure and reducing lattice disruption, as demonstrated by lower dark current densities compared to control groups.
Implementation Method 1
at least one of two adjacent layers of the superlattice structure has strain relative to the semiconductor layer
Implementation Method 2
a lattice constant of the superlattice structure is close to or equal to the lattice constant of the semiconductor layer
Data Source
AI summary
The present invention is a semiconductor device having a defect blocking region. The semiconductor device includes a substrate, a defect source region, a semiconductor layer and a defect blocking region. The defect source region is on the substrate, wherein the defect source region is a metamorphic buffer layer or a buffer layer, the semiconductor layer over the defect source region, wherein a lattice constant of the semiconductor layer is different from a lattice constant of the substrate. The defect blocking region is disposed on the substrate and below the semiconductor layer, wherein the defect blocking region includes a superlattice structure, wherein at least one of two adjacent layers of the superlattice structure has strain relative to the semiconductor layer, or a lattice constant of the superlattice structure is close to or equal to the lattice constant of the semiconductor layer.