Afterpulsing and Instability in Superconducting Nanowire Avalanche Photodetectors

We investigated the reset time of superconducting nanowire avalanche photodetectors (SNAPs) based on 30 nm wide nanowires. We studied the dependence of the reset time of SNAPs on the device inductance and discovered that SNAPs can provide a speed-up relative to SNSPDs with the same area, but with some limitations: (1) reducing the series inductance of SNAPs (necessary for the avalanche formation) could result in the detectors operating in an unstable regime; (2) a trade-off exists between maximizing the bias current margin and minimizing the reset time of SNAPs; and (3) reducing the reset time of SNAPs below ~ 1 ns resulted in afterpulsing.