Niobium superconducting nanowire single-photon detectors

TL;DR

This paper compares niobium and niobium nitride superconducting nanowire single-photon detectors, highlighting stability issues, optimization strategies, and performance metrics such as reset time and detection efficiency.

Contribution

It demonstrates stabilization techniques for niobium detectors and compares their performance to NbN detectors, revealing key differences and optimization methods.

Findings

Nb detectors are more susceptible to thermal latching than NbN.

Reducing input resistance stabilizes Nb detectors.

Nb detectors achieve about 2/3 the reset time of NbN detectors.

Abstract

We investigate the performance of superconducting nanowire photon detectors fabricated from ultra-thin Nb. A direct comparison is made between these detectors and similar nanowire detectors fabricated from NbN. We find that Nb detectors are significantly more susceptible than NbN to thermal instability (latching) at high bias. We show that the devices can be stabilized by reducing the input resistance of the readout. Nb detectors optimized in this way are shown to have approximately 2/3 the reset time of similar large-active-area NbN detectors of the same geometry, with approximately 6% detection efficiency for single photons at 470 nm.