High quality ultrathin NbN layers on sapphire for superconducting single photon detectors

Lamaëstre, R. Espiau de; Odier, P.; Bellet‐Amalric, E.; Cavalier, Paul; Pouget, Stéphanie; Villégier, J.C.

doi:10.1088/1742-6596/97/1/012046

Cited by 9 publications

(6 citation statements)

References 13 publications

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“…Great efforts have been made to improve the detection efficiency for visible and infrared photons. NbN films were deposited onto different substrates under varying conditions in order to find the most suitable NbN film parameters [6][7][8]. For detectors with optimized stoichiometry [9], the superconducting transition temperature T c varies from 10 to 11 K. Other Nb-based materials have also been considered [10].…”

Section: Introductionmentioning

confidence: 99%

“…NbN films were deposited onto different substrates under varying conditions in order to find the most suitable NbN film parameters. [6][7][8] For detectors with optimized stoichiometry 9 the superconducting transition temperature 𝑇 𝑐 varies from 10 to 11 K. Other Nb-based materials have also been considered. 10 NbTiN has a slightly smaller 𝑇 𝑐 as compared to NbN (𝑇 𝑐 of NbTiN is 1 K lower than 𝑇 𝑐 of NbN) at film thickness d < 20 nm, but it does not require such high substrate temperature to grow epitaxial films (details of the dependence of the transition temperature in NbTiN on the film thickness and growth conditions can be found in reference 11).…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of superconducting tungsten silicide WxSi1−x for single photon detection

et al. 2016

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Superconducting properties of three series of amorphous W x Si 1x films with different thickness and stoichiometry were investigated by dc transport measurements in a magnetic field up to 9 T. These amorphous W x Si 1x films were deposited by magnetron cosputtering of the elemental source targets onto silicon substrates at room temperature and patterned in the form of bridges by optical lithography and reactive ion etching. Analysis of the data on magnetoconductivity allowed us to extract the critical temperatures, superconducting coherence lengths, magnetic penetration depths, and diffusion constants of electrons in the normal state as functions of film thickness for each stoichiometry. Two basic time constants were derived from transport and time-resolving measurements. A dynamic process of the formation of a hotspot was analyzed in the framework of a diffusion-based vortex-entry model. We used a two-stage diffusion approach and defined a hotspot size by assuming that the quasiparticles and normal-state electrons have the same diffusion constant. With this definition and these measured material parameters, the hotspot in the 5-nm-thick W 0.85 Si 0.15 film had a diameter of 107 nm at the peak of the number of nonequilibrium quasiparticles. Superconducting properties of three series of amorphous W x Si 1−x films with different thickness and stoichiometry were investigated by dc transport measurements in a magnetic field up to 9 T. These amorphous W x Si 1−x films were deposited by magnetron cosputtering of the elemental source targets onto silicon substrates at room temperature and patterned in the form of bridges by optical lithography and reactive ion etching. Analysis of the data on magnetoconductivity allowed us to extract the critical temperatures, superconducting coherence lengths, magnetic penetration depths, and diffusion constants of electrons in the normal state as functions of film thickness for each stoichiometry. Two basic time constants were derived from transport and time-resolving measurements. A dynamic process of the formation of a hotspot was analyzed in the framework of a diffusion-based vortex-entry model. We used a two-stage diffusion approach and defined a hotspot size by assuming that the quasiparticles and normal-state electrons have the same diffusion constant. With this definition and these measured material parameters, the hotspot in the 5-nm-thick W 0.85 Si 0.15 film had a diameter of 107 nm at the peak of the number of nonequilibrium quasiparticles.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characteristics of superconducting tungsten silicide WxSi1−x for single photon detection

et al. 2016

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“…However, due to the significant lattice-mismatch to NbN, only poly-crystalline films, not exceeding a Tc of approximately 10K at 5nm thickness, have been demonstrated [2,8,9]. In order to increase the Tc, hence the superconducting quality of the NbN ultra-thin films, substrates with low lattice mismatch to NbN such as MgO [10][11][12], sapphire [13] and the recently demonstrated 3C-SiC have been utilized and provide an epitaxial growth resulting in increased Tc, e.g., 11.8K [14,15]. Processing and life-time issues arise with the use of MgO as a buffer-layer due to its hydrophobic nature and sensitivity to alkaline solutions.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial growth of ultra-thin NbN films on Al_xGa_1−xN buffer-layers

Krause

Meledin

Desmaris

et al. 2014

Supercond. Sci. Technol.

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The suitability of Al x Ga 1-x N epi-layer to deposit onto ultra-thin NbN films has been demonstrated for the first time. High quality single-crystal films with 5nm thickness confirmed by high-resolution transmission electron microscopy (HRTEM) have been deposited in a reproducible manner by means of reactive DC magnetron sputtering at elevated temperatures and exhibit critical temperatures (Tc) as high as 13.2K and residual resistivity ratio (RRR)~1 on hexagonal GaN epi-layer. With increasing the Al-content x in the Al x Ga 1-x N epi-layer above 20% a gradual deterioration of Tc down to 10K was observed. Deposition of NbN on bare silicon substrates served as reference and comparison. Excellent spatial homogeneity of the fabricated films was confirmed by R(T) measurements of patterned micro-bridges across the entire film area. The superconducting properties of those films were further characterized by critical magnetic field and critical current measurements. It is expected that the employment of GaN material as a buffer-layer for the deposition of ultra-thin NbN films prospectively benefit terahertz electronics, particularly hot electron bolometer (HEB) mixers.

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“…There are some examples of fabrication ultrathin films of Nb through a combined structure and electronic analysis of niobium ultrathin films (from 2 to 10 nm) formed in an ultra-high vacuum on atomically flat R -plane sapphire wafers. 100,101 Thinner than 3.3 nm, or almost the first measurement of a superconducting state, hetero-epitaxy is not possible, as shown by the textured polycrystalline morphology of the thinnest films. One monolayer (ML) is typically the thickness range over which the superconducting critical temperature rises.…”

Section: Fabrication Feasibility and Experimental Tolerancementioning

confidence: 99%

A combination of angle insensitive stopband/passband filters based on one-dimensional hyperbolic metamaterial quasiperiodic photonic crystals

et al. 2023

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High quality ultrathin NbN layers on sapphire for superconducting single photon detectors

Cited by 9 publications

References 13 publications

Characteristics of superconducting tungsten silicide WxSi1−x for single photon detection

Characteristics of superconducting tungsten silicide WxSi1−x for single photon detection

Epitaxial growth of ultra-thin NbN films on Al_xGa_1−xN buffer-layers

A combination of angle insensitive stopband/passband filters based on one-dimensional hyperbolic metamaterial quasiperiodic photonic crystals

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High quality ultrathin NbN layers on sapphire for superconducting single photon detectors

Cited by 9 publications

References 13 publications

Characteristics of superconducting tungsten silicide WxSi1−x for single photon detection

Characteristics of superconducting tungsten silicide WxSi1−x for single photon detection

Epitaxial growth of ultra-thin NbN films on AlxGa1−xN buffer-layers

A combination of angle insensitive stopband/passband filters based on one-dimensional hyperbolic metamaterial quasiperiodic photonic crystals

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Epitaxial growth of ultra-thin NbN films on Al_xGa_1−xN buffer-layers