Geiger Mode SPAD with Integrated Quenching Resistor
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Solution Overview
Problem
Avalanche photodiodes operating in Geiger mode face limitations in detecting subsequent photons due to self-sustaining avalanche-ionization processes, requiring external quenching circuits that increase complexity and cost, and separate optical sources in optoelectronic systems hinder miniaturization.
Innovation Solution
A photodetector integrating a Geiger mode avalanche photodiode with an integrated resistor, where the resistor generates infrared radiation to illuminate a sample, reducing the need for external quenching circuits and allowing simultaneous detection of photons without increasing system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a SPAD is biased at a reverse-biasing voltage higher than the breakdown voltage to enable single-photon detection, then detection sensitivity is improved, but the avalanche-ionization process becomes self-sustaining and prevents detection of subsequent photons
Solution Approach 1:
The quenching resistor is integrated directly into the SPAD device structure, allowing the device to automatically quench its own avalanche current without requiring external active control circuits. The resistor provides passive voltage division that naturally limits the voltage across the junction during avalanche, enabling self-quenching and rapid recovery for continuous photon detection
Solution Approach 2:
The quenching resistor is merged with the SPAD structure as an integrated component rather than a separate external circuit element. This integration reduces device complexity and enables faster quenching response time, allowing the SPAD to recover more quickly between photon detection events and maintain high detection rates
2Productivity
If external quenching circuits are used to prevent self-sustaining avalanche-ionization, then continuous photon detection is enabled, but device complexity and cost increase
Solution Approach 1:
The integrated quenching resistor enables the SPAD to automatically quench its own avalanche current through passive voltage division, eliminating the need for complex external active quenching circuits with multiple components and control logic
Solution Approach 2:
The quenching function is achieved using a simple passive resistor component rather than expensive active circuitry. The resistor provides sufficient quenching capability through its basic voltage division property, offering a low-cost solution that replaces complex electronic circuits
3Adaptability or versatility
If the SPAD and optical source are physically separate in optoelectronic detection systems, then system functionality is achieved, but system complexity increases and miniaturization is hindered
Solution Approach 1:
The SPAD and optical source are merged into a single integrated device structure. The optical source is positioned in direct proximity to the SPAD sensing region, allowing light to be generated and detected within the same device footprint, enabling miniaturization of optoelectronic detection systems
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
Enables efficient detection of multiple photons with reduced system complexity and cost, facilitating miniaturization and increased sensitivity in optoelectronic systems by using the integrated resistor to generate infrared radiation for sample interaction.
Implementation Method 1
the resistive region (44) is arranged at a distance from the semiconductor body (3), in particular underneath the semiconductor body (3), and is connected in series to the diode formed by the first junction
Implementation Method 2
generation of a single electron-hole pair, caused by absorption within the depleted region of a photon incident on the SPAD
Implementation Method 3
This ionization process in turn causes an avalanche multiplication of the carriers, with gains of around 106, and consequent generation in short times (hundreds of picoseconds) of the so-called avalanche current
Data Source
AI summary
A photodetector includes a Geiger mode avalanche photodiode, which includes a body of semiconductor material, which is delimited by a front surface. The avalanche photodiode further includes: a cathode region having a first type of conductivity, which forms the front surface; and an anode region having a second type of conductivity, which extends in the cathode region starting from the front surface. The photodetector further includes: a dielectric region, arranged on the front surface; a quenching resistor, which extends on the dielectric region, is electrically connected to the anode region, and is laterally spaced apart with respect to the anode region; and an optical-isolation region, which extends through the dielectric region and laterally delimits a portion of the dielectric region, the anode region extending underneath the portion of the dielectric region, the optical-isolation region being moreover interposed between the portion of the dielectric region and the quenching resistor.