Improving characterization capabilities in new single-photon avalanche diode research.

Area of Science:

• Photonics and Optoelectronics
• Semiconductor Device Physics
• Instrumentation and Measurement

Background:

• Novel single-photon avalanche diodes (SPADs) often exhibit high dark count rates, complicating device characterization.
• Fast-gating techniques used to suppress dark counts introduce large gating responses that obscure avalanche signals.
• Existing circuit-based cancellation methods for gating responses are complex and require precise tuning for each SPAD.

Purpose of the Study:

• To present an alternative, software-based method for extracting weak avalanche signals from large gating responses in SPADs.
• To simplify the characterization process for new SPAD devices, particularly those with high dark count rates.
• To demonstrate a method that eliminates the need for complex circuitry and precise per-device tuning.

Main Methods:

• Utilizing a high-speed digital storage oscilloscope (DSO) for signal acquisition.
• Employing waveform subtraction in software to isolate avalanche signals from the gating response background.
• Reducing the avalanche detection threshold to 5% of the DSO's full vertical scale or 5 mV.

Main Results:

• Successfully extracted weak avalanche signals from significant gating response interference.
• Achieved a reduced avalanche detection threshold, enabling detection of fainter signals.
• Demonstrated timing resolution better than 2 ps for typical avalanche signals.
• Facilitated easy optical alignment and calibration, with potential for on-wafer testing.

Conclusions:

• The software-based waveform subtraction method offers a simplified and effective approach to SPAD characterization.
• This technique is highly beneficial for research on new SPADs, especially those with high dark count rates or during development phases.
• The method enhances measurement precision and ease of use compared to traditional circuit-based cancellation techniques.