Stacked Silicon-Germanium Photodetector for Wavelength Alignment
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Solution Overview
Problem
Current photodetecting devices face challenges in accurately detecting different wavelengths of light due to limitations in channel alignment and dealiasing ability, particularly in image recognition applications using convolutional neural networks, where precise pixel alignment and multiple input channels are crucial for reducing error rates.
Innovation Solution
A photodetecting device is designed with vertically integrated germanium and silicon sensors, each sensitive to different peak wavelengths, allowing for improved channel alignment and dealiasing by using color filters to select or filter out specific wavelengths, and employing doped regions and readout circuits to process photo-carriers effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a photodetecting device uses multiple sensors for different wavelengths, then the ability to detect different wavelengths improves, but the channel alignment accuracy deteriorates
Solution Approach 1:
The patent transitions from lateral arrangement of multiple photodetecting components to a vertical stacked configuration. This dimensional change allows multiple sensors detecting different wavelengths to be positioned at different heights (depths) within the substrate, enabling independent optimization of each sensor's position while maintaining precise spatial correspondence for channel alignment in image recognition applications.
Solution Approach 2:
The patent implements a nested structure where multiple photodetecting components are vertically integrated within a single substrate. Each sensor is positioned at a specific depth level, with upper sensors detecting certain wavelengths and lower sensors detecting other wavelengths, creating a hierarchical arrangement that maintains precise spatial alignment while enabling multi-wavelength detection.
2Measurement precision
If pixel density is increased, then image recognition accuracy improves, but the complexity of aligning multiple input channels increases
Solution Approach 1:
By moving from 2D lateral arrangement to 3D vertical stacking, the patent resolves alignment complexity through depth-based separation. Each photodetecting component operates at a different vertical level, automatically establishing precise spatial correspondence without requiring complex lateral alignment mechanisms, thus enabling high pixel density with simplified channel alignment.
Solution Approach 2:
The patent segments the photodetecting device into multiple vertically stacked components, each responsible for detecting specific wavelength ranges. This segmentation allows independent optimization of each component's pixel arrangement while maintaining overall channel alignment, reducing the complexity of coordinating multiple input channels for image recognition.
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 solution enhances the accuracy of image recognition by improving channel alignment and dealiasing ability, leading to reduced error rates and increased pixel density, enabling efficient conversion of optical signals to electrical signals across various wavelengths.
Implementation Method 1
The first absorption region is configured to absorb photons having a first peak wavelength and to generate first photo-carriers
Implementation Method 2
The second absorption region is configured to absorb photons having a second peak wavelength and to generate second photo-carriers
Data Source
AI summary
A photodetecting device is provided. The photodetecting device includes a silicon substrate, a germanium absorption region, and a plurality of microstructures. The silicon substrate includes a first surface and a second surface. The germanium absorption region is formed proximal to the first surface of the silicon substrate, and the germanium absorption region is configured to absorb photons and to generate photo-carriers. The plurality of microstructures are formed over the second surface of the silicon substrate, and the plurality of microstructures are configured to direct an optical signal towards the germanium absorption region. A system including an optical transmitter and an optical receiver is also provided.