NIR Photodetector Circuit on Silicon With Defect-Filtered GaAs Buffers
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Solution Overview
Problem
Conventional CMOS image sensors and photodetectors face limitations in detectable wavelength range, particularly at longer wavelengths, leading to poor sensitivity in near infrared applications.
Innovation Solution
The integration of compound semiconductor materials on silicon substrates through heteroepitaxy techniques, including direct or selective heteroepitaxy, enables the fabrication of high-performance photodetector circuits with improved sensitivity and detectable wavelength range by using graded and defect-filtering buffer layers and materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicon-based CMOS sensors are used, then manufacturing maturity and cost-effectiveness are maintained, but sensitivity at longer wavelengths (near infrared) deteriorates
Solution Approach 1:
The patent employs a composite material structure consisting of a silicon substrate combined with a compound semiconductor layer (such as InGaAs). This heteroepitaxial structure leverages the manufacturing maturity of silicon while incorporating the near-infrared sensitivity of compound semiconductors, thereby extending the detectable wavelength range without sacrificing manufacturing reliability
Solution Approach 2:
The patent modifies the material composition parameter by introducing a compound semiconductor layer with specific bandgap properties suited for near-infrared detection. This parameter change enables the sensor to detect wavelengths up to 1700 nm while maintaining compatibility with existing silicon fabrication processes
2Adaptability or versatility
If compound semiconductor materials are integrated on silicon substrates through heteroepitaxy, then detectable wavelength range and sensitivity are improved, but device structure and manufacturing process complexity increase
Solution Approach 1:
The patent segments the device structure into distinct functional layers: a silicon substrate for mechanical support and electrical interconnection, a compound semiconductor layer for near-infrared detection, and optional buffer layers for defect filtering. This segmentation allows each layer to be optimized independently while maintaining overall system functionality
Solution Approach 2:
The patent introduces buffer layers (such as InGaAs buffer layers) as intermediary structures between the silicon substrate and the active photodetector region. These buffer layers serve as defect filters that reduce dislocation density and improve material quality, thereby simplifying the overall device structure despite the heteroepitaxial integration
3Manufacturing precision
If graded buffer layers are used to reduce defects in heteroepitaxial structures, then material quality and device performance are improved, but manufacturing process steps and time increase
Solution Approach 1:
The patent incorporates graded buffer layers during the epitaxial growth process itself, performing the defect-filtering action concurrently with the formation of the active device layers. This preliminary action integrates defect management into the primary manufacturing flow rather than requiring separate post-processing steps, thereby minimizing additional time consumption
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 allows for large-volume manufacturing of optoelectronic devices with enhanced sensitivity and performance metrics, suitable for applications such as LiDAR, image sensing, and other near infrared technologies.
Implementation Method 1
a photodetector device materials configured overlying the wavelength configuring material... configured for a selected wavelength
Implementation Method 2
the integration of compound semiconductor materials on silicon substrates through heteroepitaxy techniques, including direct or selective heteroepitaxy
Data Source
AI summary
A method and device for a photodetector circuit using a near infrared (NIR) compliant substrate. The substrate includes a plurality of v-grooves formed within a front region and at least a first GaAs buffer region, a defect filter layer (DFL), and a second GaAs buffer region formed overlying. The device can also include an overlying wavelength configuring material having a graded region with a plurality of material regions configured in order of concentration with respect to at least a first element concentration, which can be configured for a selected wavelength. Then, photodetector device materials can be formed overlying the wavelength configuring material and can include at least an n-type contact region, an absorber region, a p-type spacer region, and a p-type contact region. These device materials can be configured in an array of photomultiplier (PM) devices, single photon avalanche detector (SPAD) devices, or the like.