Photodetector Pixel Structure for Scattered-Light Absorption
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Solution Overview
Problem
Existing photodetectors face challenges in efficiently absorbing scattered light and reducing optical cross-talk between adjacent pixels, leading to reduced performance and increased dark current.
Innovation Solution
The introduction of additional regions in the substrate, composed of a different material from the substrate, surrounding or embedded within the absorption region, which absorb scattered light and reduce cross-talk, along with isolation regions to enhance electrical isolation between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional regions with different material are introduced in the substrate to absorb scattered light, then light absorption efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by introducing additional regions with different materials (e.g., germanium in silicon substrate, or silicon nitride) specifically in areas where scattered light absorption is needed. These regions have different optical properties than the surrounding substrate, allowing selective absorption of scattered light while maintaining the overall device structure. The additional regions are strategically positioned around the absorption region to target scattered light paths without requiring complete restructuring of the entire device.
Solution Approach 2:
The patent employs composite materials by combining the substrate material (e.g., silicon) with additional regions of different materials (e.g., germanium, silicon nitride, or other dielectric materials). This composite structure enables the device to simultaneously utilize the properties of different materials: the substrate provides the base optical absorption characteristics, while the additional regions specifically address scattered light absorption. The composite material approach resolves the contradiction by achieving improved light absorption efficiency through material diversity while keeping the structural additions localized and manageable.
2Measurement precision
If additional regions are added to reduce optical cross-talk between adjacent pixels, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the substrate into distinct functional regions: the primary absorption region for detecting optical signals and additional regions surrounding it for absorbing scattered light and reducing cross-talk. This segmentation creates clear functional boundaries between pixels, preventing optical interference between adjacent pixels. The additional regions act as isolation zones that segment the optical paths, ensuring that light intended for one pixel does not leak into neighboring pixels, thereby improving measurement precision while adding only localized structural elements.
Solution Approach 2:
The additional regions serve as intermediary structures between adjacent pixels, acting as optical barriers that prevent direct interaction between neighboring pixel regions. These intermediary regions absorb scattered light and block optical paths that would otherwise cause cross-talk, mediating the optical environment between pixels. By placing these intermediary structures only where needed at pixel boundaries, the patent reduces cross-talk without requiring complete redesign of the entire pixel array, thus limiting the increase in device complexity.
3Reliability
If isolation regions are formed to enhance electrical isolation between pixels, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent merges multiple functions into the additional regions: they simultaneously serve as optical absorption regions for scattered light, optical isolation barriers for reducing cross-talk, and electrical isolation structures. By combining these functions into a single structural element formed through integrated processing steps, the patent achieves improved electrical isolation between pixels without requiring separate manufacturing processes for each function. This merging approach reduces the cumulative precision requirements compared to implementing each isolation function separately, as the same structural features address multiple concerns simultaneously.
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
Improves light absorption efficiency, reduces optical cross-talk, and lowers dark current, thereby enhancing the overall performance and yield of the photodetector.
Implementation Method 1
an absorption region configured to receive an optical signal and to generate photo-carriers in response to the optical signal
Implementation Method 2
additional regions in the substrate, composed of a different material from the substrate, surrounding or embedded within the absorption region, which absorb scattered light and reduce cross-talk
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Methods, devices, apparatus, and systems for photo-detecting are provided. In one aspect, a photo-detecting apparatus (100) includes: a pixel (180) having an absorption region (110) configured to receive an optical signal and to generate photo-carriers in response to the optical signal, a substrate (120) supporting the absorption region (110), and at least one additional region (150) formed in the substrate. The absorption region (110) includes a first material, the substrate (120) includes a second material different from the first material. The at least one additional region (150) includes a third material different from the second material. A total area of the absorption region (110) and the at least one additional region (150) is at least 20% of an area of the pixel. Fig. 1B