Single-Photon Detector Sub-Depletion Structure for Noise Reduction
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Solution Overview
Problem
Avalanche photodiodes and single-photon avalanche diodes suffer from noise signals due to electrons generated by surface defects, which are multiplied and contribute to unwanted noise.
Innovation Solution
The single-photon detection device incorporates sub-depletion regions to prevent electrons or holes generated by surface defects from reaching the main depletion region, reducing noise by designating specific conductivity types and doping concentrations in various well and contact regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high bias voltage is applied to provide high gain in a single-photon avalanche diode, then the detection sensitivity is improved, but noise signals generated by surface defects are multiplied and increase
Solution Approach 1:
The detection device is segmented into multiple functional regions including a first well, second well, first depletion forming region, main depletion region, and first sub-depletion region. This segmentation allows different regions to perform specialized functions: the main depletion region detects photons while the sub-depletion region acts as a barrier to block carriers from surface defects, thereby reducing noise while maintaining detection sensitivity.
Solution Approach 2:
Different regions are assigned different conductivity types and doping concentrations to optimize their specific functions. The first well has first conductivity type, the second well has second conductivity type, the first depletion forming region has first conductivity type, and the first sub-depletion region is positioned between the second well and first depletion forming region. This local differentiation enables the main depletion region to maintain high electric field for sensitive detection while the sub-depletion region blocks noise carriers.
2Area of stationary object
If the depletion region is extended to improve detection coverage, then the active detection area is increased, but the impact of surface defects increases
Solution Approach 1:
The first sub-depletion region acts as an intermediary barrier between the second well and the first depletion forming region. It blocks carriers generated by surface defects from reaching the main depletion region while allowing the main depletion region to maintain its detection function. This intermediary structure increases detection area without proportionally increasing surface defect impact.
3Object-generated harmful factors
If multiple wells and depletion regions are added to reduce noise, then the noise suppression is improved, but the device structure becomes more complex
Solution Approach 1:
The device is divided into segmented regions (first well, second well, first depletion forming region, main depletion region, first sub-depletion region) with alternating conductivity types. This segmentation achieves noise suppression through the sub-depletion region barrier while maintaining a systematic and manufacturable structure that balances complexity with performance.
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 effectively reduces noise in the single-photon detection device by minimizing the impact of surface defects, enhancing signal quality and reliability.
Implementation Method 1
When an incident photon with sufficient energy to emit an electron reaches a photodiode, an electron-hole pair (EHP) is generated
Implementation Method 2
A high electric field rapidly accelerates photo-generated electrons toward (+), additional electron-hole pairs are sequentially generated due to impact ionization caused by the accelerated electrons
Implementation Method 3
As this process repeats, avalanche multiplication of photo-generated carriers and an output current occurs
Data Source
AI summary
A single-photon detection device includes a first well having a first conductivity type, a second well provided on the first well and having a second conductivity type that is different from the first conductivity type, a first depletion forming region provided on the second well and having the first conductivity type, a main depletion region provided between the first well and the second well, and a first sub-depletion region provided between the second well and the first depletion forming region, wherein the first well and the first depletion forming region are spaced apart from each other by the second well.