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

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 nmthick nanowire detectors. A 100 nm-wide straight nanowire with a length of 5 µm 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.

Photon counting of extreme ultraviolet high harmonics using a superconducting nanowire single-photon detector

“…Thus, the pulse height itself does not allow for the energy resolution of the incoming photons. The decay time of around 4 ns is determined by the kinetic inductance of the nanowire, which roughly accounts to L k = 0 2 NbN l∕(wd) ≈ 42 nH , with the vacuum permeability 0 , the magnetic penetration depth NbN ≈ 550 nm [27,31], and the nanowire's total length l = 110 m, width w = 100 nm and thickness d = 10nm. The overshoot and long tail of the signal amplitude after 4 ns is related to the reactances in the bias and readout circuit and reflections in the readout line.…”

“…The SNSPD consists of a 10 nm thick and 100 nm wide meandered niobium nitride nanowire with a gap size of 100 nm, resulting in an active area of about 4.8 × 4.8 m 2 with a filling factor of 0.5 [27]. The nanowire is embedded in a coplanar waveguide connected to a bias-tee, which separates the bias and readout lines.…”

“…Here, we demonstrate that superconducting nanowire single-photon detectors (SNSPDs) [26], which originally were also designed for infrared radiation [27], can directly be utilized for photon counting of EUV radiation from laser-driven high harmonic sources. These detectors, invented almost two decades ago [24], are based upon breaking of superconductivity in a very thin and narrow cryogenic-cooled nanowire when a photon is absorbed.…”

Mid-infrared photon counting with superconducting nanowires

“…Through this technique precise thickness control and films that are very smooth and conformal [152] can be achieved. Recent work on superconducting thin films for detectors made from NbN [153] and TiN [79] show promise but more work is needed to assess their detection properties when compared to the sputter-deposited equivalents. Ch.…”

“…Some early results on ALD NbN SNSPDs have emerged in the last couple of years. Knehr et al [153] analysed the transport properties of bare films and analaysed single photon response in non-meander SNSPDs for wavelengths up to the near-infrared. They reported saturation of internal efficiency for shorter wavelengths (λ = 385 nm).…”