Pixel Drain Structure for Precise Photon Arrival Time Binning
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Solution Overview
Problem
Current photodetectors face challenges in accurately measuring the timing of incident photons with high resolution, particularly in applications like molecular detection and sequencing, where precise temporal analysis of luminescent molecules is required, often relying on complex and costly equipment.
Innovation Solution
An integrated photodetector with a pixel structure that includes a drain configured to discard charge carriers from the photodetection region, allowing for time-binning of charge carriers with nanosecond or picosecond resolution, enabling accurate measurement of photon arrival times and reducing the need for optical filtering and complex optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a drain is added to discard charge carriers from the photodetection region, then measurement precision of photon arrival times is improved, but device complexity increases
Solution Approach 1:
The pixel is divided into distinct functional regions: a photodetection region for collecting photon-generated charge carriers and a separate drain region for discarding excess carriers. This segmentation allows independent optimization of each region's function, enabling precise time-bin measurement while maintaining manageable device complexity through modular design.
Solution Approach 2:
The drain structure is extracted as a separate functional element from the photodetection region. By providing a dedicated drain region with its own contact, the patent enables selective removal of charge carriers from specific areas without interfering with the photodetection function, thus improving measurement precision while keeping the added complexity localized and controlled.
2Measurement precision
If time-binning with nanosecond or picosecond resolution is implemented, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The drain region is designed with specific local properties: it is positioned adjacent to but distinct from the photodetection region, and is doped with a doping concentration different from the photodetection region. These localized quality differences enable the drain to selectively discard carriers without affecting the time-bin measurement precision, while the manufacturing tolerances can be relaxed compared to uniform high-precision requirements.
Solution Approach 2:
The patent utilizes doping concentration as a key parameter to differentiate the drain region from the photodetection region. By changing the doping parameter locally in the drain area, the patent achieves the desired electrical characteristics for carrier discarding without requiring extremely tight dimensional tolerances, thereby reducing manufacturing precision requirements while maintaining nanosecond or picosecond time-resolution capability.
3Productivity
If the drain is biased at operational voltage to discard carriers, then productivity of charge carrier processing is improved, but charge carrier extraction from photodetection region may occur causing measurement errors
Solution Approach 1:
The photodetection region and drain region are designed with asymmetric properties: different doping concentrations, different spatial positions, and different functional roles. This asymmetry creates an electrical field distribution where the drain can efficiently discard carriers when biased at operational voltage without creating field lines that would extract carriers from the photodetection region, thus maintaining measurement precision while achieving high carrier processing productivity.
Solution Approach 2:
Instead of trying to prevent the drain from attracting carriers (which would limit its discarding efficiency), the patent inverts the approach by designing the drain and photodetection region with distinct doping profiles and spatial arrangements. This inversion allows the drain to attract and discard carriers aggressively while the photodetection region's specialized structure prevents its carriers from being accidentally extracted, resolving the contradiction between productivity and measurement accuracy.
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
Enables precise measurement of photon arrival times, facilitating advanced applications such as DNA sequencing, fluorescence lifetime imaging, and time-of-flight imaging with reduced complexity and cost, while improving the accuracy and efficiency of molecular detection and imaging processes.
Implementation Method 1
a photodetection region configured to collect charge carriers generated in response to incident photons
Implementation Method 2
The drain may comprise a pn junction or a Schottky junction. The drain may establish a depletion region that overlaps with a depletion region of the photodetection region.
Data Source
AI summary
Some embodiments relate to an integrated circuit, comprising: a pixel, comprising: a photodetection region; and a drain configured to discard charge carriers from within a semiconductor region of the pixel outside of the photodetection region. Some embodiments relate to an integrated circuit, comprising: a pixel, comprising: a photodetection region; and a drain configured to discard charge carriers from the photodetection region, wherein the drain comprises a semiconductor region and the semiconductor region is contacted by a metal contact. Some embodiments relate to an integrated circuit, comprising: a pixel, comprising: a photodetection region; and a drain configured to discard charge carriers from the photodetection region, wherein the drain comprises a semiconductor region that to which electrical contact is made through a conductive path that does not include a polysilicon electrode.