High efficiency NbN nanowire superconducting single photon detectors fabricated on MgO substrates from a low temperature process

We demonstrate high-performance nanowire superconductingsingle photon detectors (SSPDs) on bN thin films grown at a temperaturecompatible with monolithic integration. NbN films ranging from 150nmto 3nm in thickness were deposited by dc magnetron sputtering on MgOsubstrates at 400◦C. SSPDs were fabricated on high quality NbN films ofdifferent thickness (7 to 3nm) deposited under optimal conditions. Electricaland optical characterizations were performed on the SSPDs. The highestQE value measured at 4.2K is 20% at 1300nm