Infrared Detector Layer Structure for Dislocation Filtering and High SNR
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Solution Overview
Problem
Infrared detecting devices face challenges in improving signal-to-noise ratio (SNR) due to high line defect densities caused by dislocations in the light receiving layer, which affect the device resistance and overall performance.
Innovation Solution
The use of a dislocation filter layer with specific composition and thickness, such as Aly(1)In1-y(1)Sb, is implemented to reduce line defect densities by bending dislocations laterally, thereby increasing the device resistance and improving SNR without increasing film formation time or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional semiconductor structure is used, then the device structure is simple, but the line defect density is high due to lattice constant mismatch
Solution Approach 1:
The first layer is segmented into multiple sub-layers with different Al compositions (first AlInSb layer, second AlInSb layer with different composition, and intermediate layer). This segmentation allows each sub-layer to have optimized properties for reducing dislocation density while maintaining overall device functionality.
Solution Approach 2:
Different regions of the first layer have different Al compositions tailored to specific functions: the first AlInSb layer has one composition range, the second AlInSb layer has another composition range, and the intermediate layer has yet another composition. This local quality variation optimizes dislocation filtering at each interface while managing lattice mismatch locally.
2Reliability
If the Al composition in the first layer is increased to reduce defects, then the device resistance increases, but the photocurrent decreases
Solution Approach 1:
The Al composition parameter is varied across different sub-layers of the first layer. By changing the Al composition from the first AlInSb layer through the intermediate layer to the second AlInSb layer, the device achieves optimized resistance while maintaining photocurrent through gradual parameter transition rather than abrupt changes.
Solution Approach 2:
The first layer is constructed as a composite structure with multiple AlInSb layers having different Al compositions and an intermediate layer. This composite approach allows the device to benefit from the high resistance properties of Al-rich regions while maintaining photocurrent through In-rich regions and optimized interfaces.
3Reliability
If the film thickness of the intermediate layer is increased, then the defect filtering effect is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The film thickness of the intermediate layer is optimized within a specific range (50-500 nm) to achieve effective defect filtering without excessive thickness. This parameter optimization balances the defect filtering effect with manufacturability, avoiding the need for extremely precise thickness control while still achieving significant dislocation 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
This approach effectively enhances the SNR of infrared detecting devices by suppressing defective recombination through dislocations, leading to improved resistivity and device performance.
Implementation Method 1
a dislocation filter layer having a film thickness ty(1) and containing Aly(1)In1-y(1)Sb (0≤y(1)≤1), wherein line defects bend in a lateral direction in the first layer
Data Source
AI summary
Disclosed is an infrared detecting device with a high SNR. The infrared detecting device includes a semiconductor substrate; a first layer formed on the semiconductor substrate and having a first conductivity type; a light receiving layer formed on the first layer; and a second layer formed on the light receiving layer and having a second conductivity type. 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.