AlInSb Infrared Detector Passivation for Dark Current Reduction
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Solution Overview
Problem
InSb-based infrared detectors face limitations in electro-optical performance and operating temperatures due to manufacturing process-related defects and non-optimal material systems, leading to undesirable dark current and reduced performance.
Innovation Solution
The use of an AlxIn(1-x)Sb absorber layer with an AlyIn(1-y)Sb passivation layer, where x<y, along with a junction and metal contact, enhances electro-optical performance by minimizing defects and allowing for improved temperature operation through epitaxial growth and specific doping techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing processes are used with non-optimal material systems, then manufacturing simplicity is maintained, but detector performance deteriorates with increased dark current and reduced electro-optical performance
Solution Approach 1:
The patent employs composite material structures including AlInSb absorber layers combined with InSb buffer layers and contact layers. This composite approach optimizes both electro-optical performance and manufacturing feasibility by selecting materials with compatible lattice constants and beneficial electrical properties for each functional region of the detector
Solution Approach 2:
The patent systematically varies compositional parameters (Al content x in AlxIn1-xSb), doping concentrations (Nd, Na), and layer thicknesses to optimize detector performance. By controlling these parameters during epitaxial growth, the invention achieves reduced dark current and improved electro-optical characteristics while maintaining manufacturing processability
2Temperature
If conventional detectors are used, then manufacturing simplicity is maintained, but operating temperature capability deteriorates with insufficient maximum operating temperatures
Solution Approach 1:
The patent raises the operating temperature capability by changing material composition parameters and doping levels. The AlInSb/InSb heterostructure with optimized Al content and doping concentrations enables thermal management that allows operation at higher temperatures than conventional InSb detectors, extending operational flexibility
3Reliability
If conventional material systems are used, then manufacturing simplicity is maintained, but dark current increases to undesirable levels
Solution Approach 1:
The patent applies local quality optimization by creating distinct functional layers with specific properties: InSb buffer layers provide low-defect foundations, AlInSb absorber layers provide optimal photoresponse, and doped contact layers provide efficient charge collection. Each layer is locally optimized for its specific function, resulting in reduced dark current throughout the device structure
Solution Approach 2:
The patent introduces InSb buffer layers and intermediate contact layers as intermediary structures between the substrate and active regions. These intermediary layers serve as defect filters and transition regions that reduce dark current generation while maintaining manufacturing feasibility through standard epitaxial growth processes
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 and allows for increased operating temperatures, reducing dark current and enhancing detector performance in infrared applications, particularly in the 3-5 micron wavelength band.
Implementation Method 1
InSb-based detectors (e.g., photodiode) are used in many infrared (IR) sensor applications... In particular, InSb-based detectors have found particular use in infrared detection and imaging applications in the 3-5 micron IR wavelength band
Implementation Method 2
forming, by epitaxial growth in one growth run, an AlxIn(1-x)Sb absorber layer above a surface of the InSb substrate and an AlyIn(1-y)Sb passivation layer above the AlxIn(1-x)Sb absorber layer
Data Source
AI summary
In one embodiment, a detector includes an AlxIn(1-x)Sb absorber layer, and an AlyIn(1-y)Sb passivation layer disposed above the AlxIn(1-x)Sb absorber layer, wherein 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.