We report on the extended infrared single-photon response of niobium nitride superconducting nanowires deposited by atomic layer deposition. The nanowire detectors are based 4.65 nm thick NbN, patterned into 100 meanders, and characterized at 2.5 K. verify sensitivity from 1310 to 2006 with saturated shorter wavelengths.

The structural and electronic properties of three isostructural transition metal nitrides VN, NbN and TaN have been calculated using the full-potential linearized augmented plane-wave method within a generalized gradient approximation scheme for the exchange-correlation potential. Perfect NaCl structures as well as lattices containing nitrogen vacancies (M4N3), and an hexagonal e-M2N structure ...

We present an optical setup that can be used to characterize the thicknesses of thin NbN films to screen samples for fabrication and to better model the performance of the resulting superconducting nanowire single photon detectors. The infrared transmissometer reported here is easy to use, gives results within minutes, and is nondestructive. Thus, the thickness measurement can be easily integra...

We exploit nonlinearity in NbN superconducting stripline resonators, which originates from local thermal instability, for studying stochastic resonance. As the resonators are driven into instability, small amplitude modulation (AM) signals are amplified with the aid of injected white noise. Simulation results based on the equations of motion for the system yield a good agreement with the experi...

Superconducting niobium nitride thin films are used for a variety of photon detectors, quantum devices, and superconducting electronics. Most these applications require highly uniform films, instance, when moving from single-pixel detectors to arrays with large active area. Plasma-enhanced atomic layer deposition (ALD) is feasible option produce high-quality, conformal has been demonstrated as ...

Superconducting fluctuations in long and narrow strips made from ultrathin NbN films, have been investigated. For large bias currents close to the critical current fluctuations led to localized, temporary transitions into the normal conducting state, which were detected as voltage transients developing between the strip ends. We present models based on fluctuations in the Cooper pair density an...

Using time-domain terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparti...