AlInSb Detector Structure for Infrared Imaging
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Solution Overview
Problem
InSb-based infrared detectors face limitations in electro-optical performance and operating temperatures due to defects in manufacturing processes, such as non-optimal material systems and unpassivated surface states, leading to increased dark current and reduced performance.
Innovation Solution
The use of AlzIn(1-z)Sb passivation/etch stop layers, AlxIn(1-x)Sb absorber layers, and AlyIn(1-y)Sb passivation layers, formed epitaxially during a single growth run, to create a detector structure with improved interface quality and reduced defects, along with a junction and metal contact configuration, enhances electro-optical performance and operating temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing processes are used for InSb-based detectors, then the manufacturing process is simple, but the electro-optical performance deteriorates due to defects and unpassivated surface states
Solution Approach 1:
The patent employs composite material structures including AlInSb passivation/etch stop layers, InSb absorber layers, and InAlAs contact layers. These composite material systems resolve the technical contradiction by providing both improved electro-optical performance through proper passivation and defect reduction, while maintaining manufacturing feasibility through epitaxial growth processes that can integrate multiple layers in a single growth run.
Solution Approach 2:
The patent utilizes parameter changes in the epitaxial growth process, specifically varying composition ratios (x, y, z in AlxIn1-xSb and AlyIn1-ySb), layer thicknesses, and growth conditions to optimize both performance and manufacturability. By controlling these parameters, the process achieves high-quality interfaces and passivation without requiring excessively complex manufacturing steps.
2Reliability
If conventional passivation methods are used, then the manufacturing process is straightforward, but dark current increases due to unpassivated surface states
Solution Approach 1:
The patent employs composite material structures including AlInSb passivation/etch stop layers, InSb absorber layers, and InAlAs contact layers. These composite material systems resolve the technical contradiction by providing both improved electro-optical performance through proper passivation and defect reduction, while maintaining manufacturing feasibility through epitaxial growth processes that can integrate multiple layers in a single growth run.
Solution Approach 2:
The patent applies local quality by implementing different material compositions and properties at different locations and interfaces within the detector structure. Specifically, AlInSb layers with specific composition ratios are positioned at critical interfaces (substrate-absorber and absorber-contact) to provide localized passivation and defect reduction exactly where needed, rather than uniform treatment throughout the entire structure.
3Temperature
If standard InSb material systems are used, then the material system is simple, but operating temperature is limited due to performance degradation
Solution Approach 1:
The patent utilizes parameter changes in the epitaxial growth process, specifically varying composition ratios (x, y, z in AlxIn1-xSb and AlyIn1-ySb), layer thicknesses, and growth conditions to optimize both performance and manufacturability. By controlling these parameters, the process achieves high-quality interfaces and passivation without requiring excessively complex manufacturing steps.
Solution Approach 2:
The patent applies local quality by implementing different material compositions and properties at different locations and interfaces within the detector structure. Specifically, AlInSb layers with specific composition ratios are positioned at critical interfaces (substrate-absorber and absorber-contact) to provide localized passivation and defect reduction exactly where needed, rather than uniform treatment throughout the entire structure.
4Reliability
If multiple separate growth runs are used to form different layers, then each layer can be optimized independently, but manufacturing time and process complexity increase
Solution Approach 1:
The patent merges multiple layer formation operations into a single epitaxial growth run. The method integrates formation of the InSb substrate, AlInSb passivation/etch stop layers, InSb absorber layers, and InAlAs contact layers in one continuous process, eliminating the need for separate growth runs. This maintains interface quality through in-situ growth while significantly improving manufacturing efficiency.
Solution Approach 2:
The epitaxial growth process is designed to perform multiple functions simultaneously: forming passivation layers, creating absorber layers, establishing contact layers, and defining interface structures all in one operation. This multi-functional approach resolves the contradiction by achieving comprehensive layer optimization without requiring multiple separate process steps.
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 configuration improves electro-optical performance, reduces dark current, and allows for increased operating temperatures, leading to enhanced performance in infrared detection and imaging applications, particularly in the 3-5 micron wavelength band.
Implementation Method 1
formed epitaxially during a single growth run
Data Source
AI summary
In one embodiment, a detector includes an AlzIn(1-x)Sb passivation/etch stop layer, an AlxIn(1-x)Sb absorber layer disposed above the Alzn(1-z)Sb passivation/etch stop layer, and an AlyIn(1-y)Sb passivation layer disposed above the AlxIn(1-x)Sb absorber layer, wherein x<z and x<y. The detector further includes a junction formed in a region of the AlxIn(1−x)Sb absorber layer, and a metal contact disposed above the junction and through the AlyIn(1-y)Sb passivation layer.