Demonstration of Single Photon Detection in Amorphous Molybdenum Silicide / Aluminium Superconducting Nanostrip

Single photon detectors (SPD) are largely used when the signal to be measured is particularly low or if high accuracy, timing resolution and low noise are required. About twenty years ago, a new type of SPD based on superconducting materials appeared, and today these devices present the best performances in terms of efficiency, noise, counting rate, detectable wavelength, dead time, and timing jitter. In this work, we first describe the working principle of Superconducting Nanostrips Single Photon Detectors (SNSPDs) and provide a brief overview of the main properties and applications. Then, we present the results of the fabrication and characterization of Molybdenum Silicide SNSPDs with a cover layer of a thin Aluminium film (MoSi/Al). MoSi has already been adopted to fabricate SNSPDs, and in this work, we prove that the additional Al layer enhances the operating conditions without compromising the detection likelihood and leaving unaltered the properties of the device, even over a temporal window of two years and after several thermal cycles.