# Nanowire single-photon detectors made of atomic layer-deposited niobium nitride

## TL;DR

This paper reports the development and characterization of superconducting nanowire single-photon detectors made from atomic layer-deposited NbN, demonstrating their effectiveness and potential for scalable, conformal detector fabrication.

## Contribution

It introduces the use of atomic layer deposition for NbN nanowire detectors, showing comparable transport properties to sputtered films and effective single-photon detection capabilities.

## Key findings

- ALD NbN films have similar critical current ratios to sputtered films.
- Nanowire detectors exhibit saturated count-rate and near-infrared cut-off wavelength.
- Potential for wafer-scale and conformal fabrication of NbN-based detectors.

## Abstract

We demonstrate and characterize first superconducting nanowire single-photon detectors (SNSPDs) made from atomic layer-deposited (ALD) NbN layers. To assess the suitability of these films as a detector material, transport properties of bare films and bridges of different dimensions and thicknesses are investigated. Similar ratios of the measured critical current to the depairing current are obtained for micro-bridges made from ALD and sputtered NbN films. Furthermore, we characterized the single-photon response for 5 and 10 nm-thick nanowire detectors. A 100 nm-wide straight nanowire with a length of 5 $\mu$m exhibits saturated count-rate dependencies on bias current and a cut-off wavelength in the near-infrared range. The ALD technique could open up the possibility to fabricate NbN-based detectors on the wafer scale and to conformally cover also non-planar surfaces for novel device concepts.