Photo-Detection Apparatus Potential Gradient Noise Suppression
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Solution Overview
Problem
Conventional photo-detection apparatuses face challenges in reducing noise charges generated by the tunnel effect while maintaining high photo-detection efficiency, as the area of the detection region affects both noise suppression and efficiency, leading to a trade-off between these factors.
Innovation Solution
The apparatus employs a semiconductor substrate with a specific structure of semiconductor regions, including a first and second conductivity type, where the potential differences between these regions are optimized to inhibit avalanche breakdown and noise generation, allowing signal charges to move efficiently while reducing noise charges through a controlled potential gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the area of the detection region is increased, then photo-detection efficiency is improved, but noise charges generated by the tunnel effect increase
Solution Approach 1:
The patent applies local quality by creating different potential conditions in different regions of the semiconductor structure. The first semiconductor region has a higher potential than the second semiconductor region, forming a potential gradient that locally directs signal charges toward the detection region while suppressing tunnel effect noise in other areas. This spatial variation in potential quality allows the detection region to maintain high efficiency while surrounding regions suppress noise generation.
Solution Approach 2:
The patent segments the semiconductor structure into multiple distinct regions with different potentials and conductivity types. The first semiconductor region (higher potential) is separated from the second semiconductor region (lower potential) by a junction, creating distinct functional zones. This segmentation allows the detection region to be optimized for signal detection while other segments are optimized for noise suppression, resolving the contradiction between detection efficiency and noise reduction.
2Object-generated harmful factors
If the area of the detection region is decreased, then noise charges are suppressed, but photo-detection efficiency is lowered
Solution Approach 1:
The patent resolves the area-based trade-off by introducing a potential dimension. Instead of relying solely on the two-dimensional area of the detection region, the invention uses the third dimension of electrical potential to control charge carrier behavior. By establishing a potential gradient between the first and second semiconductor regions, the system can suppress noise and enhance signal detection without being constrained by the planar area of the detection region, thus breaking the traditional trade-off relationship.
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 configuration effectively reduces noise charges and maintains high photo-detection efficiency by optimizing the potential differences between semiconductor regions, preventing avalanche breakdown and enhancing signal charge movement.
Implementation Method 1
a single photon avalanche diode (SPAD) in which a photocarrier originating from a single photon causes avalanche amplification in a PN junction region
Implementation Method 2
perform photoelectric conversion
Implementation Method 3
A strong electric field is generated in the region where an electric charge is detected and thus, there is a possibility of a tunnel effect being produced in the PN junction by the strong electric field
Data Source
AI summary
An apparatus wherein, in plane view, a first semiconductor region of a first conductivity type overlaps at least a portion of a third semiconductor region, a second semiconductor region overlaps at least a portion of a fourth semiconductor region of a second conductivity type, a height of a potential of the third semiconductor region with respect to an electric charge of the first conductivity type is lower than that of the fourth semiconductor region, and a difference between a height of a potential of the first semiconductor region and that of the third semiconductor region is larger than a difference between a height of a potential of the second semiconductor region and that of the fourth semiconductor region.