Avalanche Photodiode Buried N Structure Depletion Expansion
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Solution Overview
Problem
Avalanche diodes face challenges in enhancing near-infrared photon detection probability and minimizing transit time, particularly due to the limited expansion of the depletion region by reverse bias voltage, which requires excessive voltage and results in poor lateral extension and increased transit time.
Innovation Solution
Incorporating a buried N structure with elongated N components within the P region to expand the depletion region without increasing the reverse bias voltage, allowing for enhanced photon detection and reduced transit time by creating a more efficient electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse bias voltage is increased to expand the depletion region, then photon detection probability is improved, but power consumption increases and transit time increases
Solution Approach 1:
The P region is segmented into multiple portions with different doping concentrations, creating a graded doping profile. This segmentation allows the depletion region to extend more effectively through the P region without requiring proportionally higher reverse bias voltage, thus improving photon detection probability while controlling power consumption
Solution Approach 2:
Different portions of the P region are assigned different doping concentrations (first doping concentration in first portion, second doping concentration in second portion). This local quality variation optimizes the electric field distribution, enabling better depletion region expansion efficiency and reducing the voltage needed for effective photon detection
2Reliability
If reverse bias voltage is increased to expand the depletion region, then photon detection probability is improved, but transit time increases
Solution Approach 1:
The P region is divided into portions with different doping concentrations, creating a segmented structure that optimizes carrier transport. This segmentation enables faster carrier collection by creating favorable electric field gradients, reducing transit time while maintaining effective depletion region expansion for high photon detection probability
Solution Approach 2:
The doping concentration parameter is varied across different portions of the P region (first doping concentration vs. second doping concentration). This parameter change optimizes the balance between depletion region width and carrier drift velocity, achieving both high photon detection probability and reduced transit time
3Reliability
If the P region is made thicker to improve near-infrared photon detection, then photon detection probability is improved, but depletion region expansion becomes less effective
Solution Approach 1:
The P region is structured with different doping concentrations in different portions, creating local quality variations. This allows the thicker P region to be effectively depleted by optimizing the electric field distribution through graded doping, maintaining high near-infrared photon detection probability while ensuring complete depletion region expansion
Solution Approach 2:
The doping concentration parameter is changed across the P region thickness (first doping concentration in first portion, second doping concentration in second portion). This parameter gradient enables effective depletion region expansion through the thicker P region structure, improving near-infrared photon detection without sacrificing depletion efficiency
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 approach enhances near-infrared photon detection probability while maintaining a low reverse bias voltage, reducing dark current and power consumption, and increasing the maximum count rate by ensuring thorough depletion and efficient carrier funneling.
Implementation Method 1
The PN junction is reverse biased at a voltage exceeding a breakdown voltage. In this way, a carrier generated by a single photon can be injected into a depletion region and can cause a self-sustaining avalanche.
Implementation Method 2
a carrier generated by a single photon can be injected into a depletion region
Implementation Method 3
The at least one depletion structure includes at least one component of the first dopant type arranged to fully deplete the at least one second region within the depletion region
Data Source
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AI summary
The present disclosure relates to an avalanche diode (102), comprising a PN junction (4) formed by a first region (8) of a first conductivity type and a second region (6) of a second conductivity type. A depletion structure (14) comprising components (16a-16g) of a first conductivity type is located adjacent to the PN junction (4). The depletion structure (14) is designed to expand the depletion region (10) without increasing the reverse bias voltage. Two electrodes, respectively connected to the first region (8) and the second region (6), polarise the PN junction (4).