Epitaxial Growth of Sputtered Ultra-Thin NbN Layers and Junctions on Sapphire

Villégier, J.C.; Bouat, Sophie; Cavalier, Paul; Setzu, Romano; Lamaëstre, R. Espiau de; Jorel, Corentin; Odier, P.; Guillet, Bruno; Méchin, Laurence; Chauvat, Marie-Pierre; Ruterana, P.

doi:10.1109/tasc.2009.2019243

Cited by 43 publications

(33 citation statements)

References 14 publications

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“…• C in our case 9 as shown on Fig.2. The accessible technology led to the choice of a Si 3 N 4 ridge waveguide, with a refractive index of 1.96 measured by ellipsometry, deposited over a 1-D array of 24 epi-NbN nanowires grown on R-Sapphire substrate.…”

Section: A Technological Constraints On Device Designsupporting

confidence: 54%

“…3. A 4nm-thick epitaxial NbN is first DC-magnetron sputtered on the heated R-plane Sapphire 4-inch wafer, 9 and patterned afterwards by electron-beam lithography with a VB6 UHR tool from VISTEC, using the negative tone resist NEB35 from Sumitomo. This resist, with a thickness of 45nm, allows good reproducibility of ∼40nm wide nanowires and 160nm pitch with 90μC/cm 2 dose to size (±10% process window).…”

Section: Device Fabricationmentioning

confidence: 99%

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Light interference detection on-chip by integrated SNSPD counters

Cavalier

Villégier

Feautrier³

et al. 2011

AIP Advances

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A SWIFTS device (Stationary Wave Integrated Fourier Transform Spectrometer) has been realized with an array of 24 Superconducting Nanowire Single Photon Detectors (SNSPD), on-chip integrated under a Si3N4 monomode rib-waveguide interferometer. Colored light around 1.55μm wavelength is introduced through end-fire coupling, producing a counter-propagative stationary interferogram over the 40nm wide, 120nm spaced, 4nm thick epi-NbN nanowire array. Modulations in the source bandwidth have been detected using individual waveguide coupled SNSPDs operating in single photon counting mode, which is a step towards light spectrum reconstruction by inverse Fourier transform of the stationary wave intensity. We report the design, fabrication process and in-situ measurement at 4.2K of light power modulation in the interferometer, obtained with variable laser wavelength. Such micro-SWIFTS configuration with 160nm sampling period over 3.84μm distance allows a spectral bandwidth of 2μm and a wavelength resolution of 170nm. The light interferences direct sampling ability is unique and raises wide interest with several potential applications like fringe-tracking, metrology, cryptography or optical tomography.

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Section: A Technological Constraints On Device Designsupporting

confidence: 54%

Section: Device Fabricationmentioning

confidence: 99%

Light interference detection on-chip by integrated SNSPD counters

Cavalier

Villégier

Feautrier³

et al. 2011

AIP Advances

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“…NbN layers were deposited by dc magnetron sputtering from a six-inches diameter niobium target in a reactive (nitrogen/argon) gas mixture at 300 C. The same target is used for Nb deposition applying only argon pressure, whereas the MgO layer is rf-magnetron sputtered from an MgO target. More details on the technique can be found in [9]. The NbN top layer is further reactive ion etched on a part of the wafer to provide the bulk niobium reference sample (Ref).…”

Section: Methodsmentioning

confidence: 99%

Characterization of superconducting nanometric multilayer samples for superconducting rf applications: First evidence of magnetic screening effect

Antoine

Berry

Bouat

et al. 2010

Phys. Rev. ST Accel. Beams

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The best rf bulk niobium accelerating cavities have nearly reached their ultimate limits at rf equatorial magnetic field H % 200 mT close to the thermodynamic critical field H c . In 2006 Gurevich proposed to use nanoscale layers of superconducting materials with high values of H c > H c Nb for magnetic shielding of bulk niobium to increase the breakdown magnetic field of superconducting rf cavities. Depositing good quality layers inside a whole cavity is rather difficult, so as a first step, characterization of single layer coating and multilayers was conducted on high quality sputtered samples by applying the technique used for the preparation of superconducting electronics circuits. The samples were characterized by x-ray reflectivity, dc resistivity (PPMS), and dc magnetization (SQUID) measurements. Dc magnetization curves of a 250 nm thick Nb film have been measured, with and without a magnetron sputtered coating of a single or multiple stack of 15 nm MgO and 25 nm NbN layers. The Nb samples with/without the coating exhibit different behaviors and clearly show an enhancement of the magnetic penetration field. Because SQUID measurements are influenced by edge and shape effects, we propose to develop a specific local magnetic measurement of H C1 based on ac third harmonic analysis in order to reveal the true screening effect of multilayers.

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“…• C temperature range [1,9]. According to literature, NbN growth on the MgO substrate results in the best values of T c , e.g., T c = 12 K for a 4 nm thick film [10].…”

Section: Introductionmentioning

confidence: 97%

Ultrathin NbN Films for Superconducting Single-Photon Detectors

et al. 2011

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We present our research on fabrication and structural and transport characterization of ultrathin superconducting NbN layers deposited on both single-crystal Al2O3 and Si wafers, and SiO2 and Si3N4 buffer layers grown directly on Si wafers. The thicknesses of our films varied from 6 nm to 50 nm and they were grown using reactive RF magnetron sputtering on substrates maintained at the temperature 850• C. We have performed extensive morphology characterization of our films using the X-ray diffraction method and atomic force microscopy, and related the results to the type of the substrate used for the film deposition. Our transport measurements showed that even the thinnest, 6 nm thick NbN films had the superconducting critical temperature of 10-12 K, which was increased to 14 K for thicker films.

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Epitaxial Growth of Sputtered Ultra-Thin NbN Layers and Junctions on Sapphire

Cited by 43 publications

References 14 publications

Light interference detection on-chip by integrated SNSPD counters

Light interference detection on-chip by integrated SNSPD counters

Characterization of superconducting nanometric multilayer samples for superconducting rf applications: First evidence of magnetic screening effect

Ultrathin NbN Films for Superconducting Single-Photon Detectors

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