Avalanche Photodiode Array Isolation for Dark Current Control
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Solution Overview
Problem
Existing light detectors face issues with reliability due to potential erroneous light detection caused by dark current and crosstalk noise, which affect the accuracy and stability of light sensing.
Innovation Solution
The light detector design incorporates a p -< -type semiconductor region and an n +< -type semiconductor region separated by a separation part, with a quenching part to suppress avalanche breakdown and a second interconnect to stabilize electric potential, reducing dark current and crosstalk noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light detector uses a semiconductor region with high sensitivity to detect light, then the detection capability is improved, but dark current increases causing erroneous detection
Solution Approach 1:
The semiconductor substrate is divided into multiple independent pixel regions, each with its own photoelectric conversion element. This segmentation isolates dark current generation in one pixel from affecting other pixels, reducing crosstalk and erroneous detection while maintaining high sensitivity in each individual pixel.
Solution Approach 2:
An intermediate layer or structure is introduced between adjacent pixels to prevent dark current and noise from propagating between neighboring photoelectric conversion elements. This intermediary structure acts as a barrier that maintains signal integrity while allowing each pixel to operate at high sensitivity.
2Ease of manufacture
If the light detector structure is simplified to reduce manufacturing complexity, then ease of manufacture is improved, but crosstalk noise increases affecting detection accuracy
Solution Approach 1:
The detector is segmented into modular pixel units that can be manufactured using standard semiconductor fabrication processes. Each pixel is a self-contained module with clear boundaries, allowing for scalable production while maintaining isolation between elements to prevent crosstalk noise.
Solution Approach 2:
Different regions of the semiconductor substrate are assigned different properties: photoelectric conversion regions with high sensitivity materials, isolation regions with different doping or material composition to block noise, and selective areas for light incidence. This local differentiation enables both ease of manufacture through standardized processes and high signal accuracy through optimized local characteristics.
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 design enhances the reliability of the light detector by minimizing erroneous light detection and improving signal accuracy through reduced dark count rates and crosstalk noise, ensuring stable photon detection efficiency.
Implementation Method 1
comprises a multiplication region which causes avalanche multiplication of carriers by a high electric field region
Implementation Method 2
a sensor chip comprising: a semiconductor substrate comprising a pixel array part wherein a plurality of pixels are positioned in an array arrangement; a photoreceptor element which is disposed on the semiconductor substrate for each of the pixels
Data Source
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AI summary
A light detector (1) includes a plurality of elements (10), a plurality of insulating separation parts (20), a fourth semiconductor region (14), a fifth semiconductor region (15), a first interconnect, a first quenching part, and a second interconnect. Avalanche photodiodes (10) are located in a cell region and arranged in a plane. Each of the elements (10) includes first, second, and third semiconductor regions (11, 12, 13). The second semiconductor region (12) is located on the first semiconductor region (11). The third semiconductor region (13) is located on the second semiconductor region (12). The separation parts (20) are located respectively around the elements (10). The fourth semiconductor region (14) is located around each of the separation parts (20). The fifth semiconductor region (15) is located on the fourth semiconductor region (14). The first interconnect is electrically connected to the third semiconductor regions (13). The first quenching part is electrically connected to the first interconnect. The second interconnect is electrically connected to the fifth semiconductor region (15). Carriers that are generated in the p--type semiconductor region (14) flow toward n+-type semiconductor region (15) due to depletion layer (DL2). A lateral electric field is generated below separation part (20). The carriers that are generated below the separation part (20) are attracted toward depletion layer (DL2) by the lateral electric field and are ejected via the second interconnect. Thereby, dark electric current that flows toward the first interconnect can be suppressed and reliability of the light detector (1) can be increased.