  High-quality ultra-thin films of niobium nitride (NbN) are developed by
plasma-enhanced atomic layer deposition (PEALD) technique. Superconducting
nanowire single-photon detectors (SNSPDs) patterned from this material exhibit
high switching currents and saturated internal efficiencies over a broad bias
range at 1550 nm telecommunication wavelength. Statistical analyses on hundreds
of fabricated devices show near-unity throughput yield due to exceptional
homogeneity of the films. The ALD-NbN material represents an ideal
superconducting material for fabricating large single-photon detector arrays
combining high efficiency, low jitter, low dark counts.
