Negative Feedback Avalanche Diode for High-Speed Single-Photon Detection
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Solution Overview
Problem
Current single-photon avalanche detectors are limited in operational speed and wavelength range, particularly for wavelengths greater than 1000 nm, due to issues with afterpulsing and capacitance-related constraints, which restrict their use in high-speed applications such as quantum information processing and imaging.
Innovation Solution
A thin-film resistor is monolithically integrated with the avalanche photodiode to provide passive quenching, reducing capacitance and enabling operation at speeds exceeding 10 MHz for wavelengths between 1000 to 1600 nm without significant increases in capacitance, thus allowing for high-repetition-rate single-photon detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-photon avalanche detector is designed for wavelengths greater than 1000 nm, then wavelength detection capability is improved, but operational speed deteriorates due to afterpulsing and capacitance constraints
Solution Approach 1:
The device is segmented into distinct functional regions: an absorption layer for photon detection, a multiplication region for avalanche gain, and a quenching region with a thin-film resistor for rapid avalanche termination. This segmentation allows each region to be optimized independently, enabling high-speed operation at wavelengths greater than 1000 nm by reducing the time carriers spend in each region while maintaining detection efficiency
Solution Approach 2:
The patent changes key parameters including the thickness and doping concentration of the absorption layer, the electric field distribution in the multiplication region, and the resistance value of the thin-film resistor. By optimizing these parameters, the device achieves rapid avalanche quenching (reducing afterpulsing) while maintaining high detection efficiency at wavelengths greater than 1000 nm, thereby improving operational speed without sacrificing wavelength detection capability
2Reliability
If passive quenching is implemented to reduce afterpulsing, then detection accuracy is improved, but capacitance increases which limits operational speed
Solution Approach 1:
A thin-film resistor is introduced as an intermediary element between the absorption layer and the readout circuit. This resistor provides passive quenching by rapidly draining excess carriers and terminating the avalanche process, thereby reducing afterpulsing and improving detection accuracy. The thin-film configuration minimizes the added capacitance, allowing operational speeds to exceed 10 MHz while maintaining high detection reliability
3Productivity
If the detector is re-armed quickly to increase repetition rate, then productivity is improved, but afterpulsing increases which reduces reliability
Solution Approach 1:
The quenching region with the thin-film resistor is pre-configured to rapidly terminate the avalanche process immediately after photon detection. This preliminary quenching action clears trapped carriers before the detector is re-armed, suppressing afterpulsing. The fast quenching time constant allows the detector to be re-armed quickly with a repetition rate exceeding 10 MHz while maintaining low afterpulsing and high reliability
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 enables efficient single-photon detection at wavelengths beyond 1000 nm with repetition rates greater than 10 MHz, overcoming the limitations of prior art by minimizing afterpulsing and maintaining rapid rearming capabilities.
Implementation Method 1
A thin-film resistor and avalanche photodiode are monolithically integrated wherein the thin-film resistor provides negative feedback to the avalanche photodiode
Implementation Method 2
As the free carriers travel through the multiplication region, they collide with other carriers bound in the atomic lattice of the semiconductor, thereby generating more free carriers through a process called 'impact ionization'
Implementation Method 3
An avalanche photodiode is characterized by its 'breakdown voltage.' A photodiode's breakdown voltage is a bias level above which free-carrier generation can become self-sustaining and result in run-away avalanche
Implementation Method 4
enabling operation at speeds exceeding 10 MHz for wavelengths between 1000 to 1600 nm without significant increases in capacitance
Data Source
AI summary
A single-photon avalanche detector is disclosed that is operable at wavelengths greater than 1000 nm and at operating speeds greater than 10 MHz. The single-photon avalanche detector comprises a thin-film resistor and avalanche photodiode that are monolithically integrated such that little or no additional capacitance is associated with the addition of the resistor.