Propriétés et structure des couches minces de nitrure de niobium élaborées par pulvérisation cathodique réactive I. Élaboration et propriétés

Spitz, J.; Chevallier, J.; Aubert, A.

doi:10.1016/0022-5088(74)90230-6

Cited by 20 publications

(4 citation statements)

References 12 publications

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“…For example, the highest critical temperatures are obtained on the 8-NbN phase, and superconductivity disappears as soon as the ratio [N ]/ [Nb ] of the nitrogen to the niobium atoms in the film reaches 1.5. At the same time, resistivity at ambient temperature drastically increases [8].…”

mentioning

confidence: 91%

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From localization to superconductivity in granular niobium nitride thin films

Cabanel¹,

Chaussy²,

Mazuer³

et al. 1988

J. Phys. France

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The variations with temperature T of the resistivities of reactively sputtered NbN films have been studied from 1 to 300 K. The nitrogen concentration in the films has been increased by using higher and higher nitrogen pressures during sputtering. The porosity of the films is also increased and this favours their post oxidation at ambient atmosphere. The oxygen concentration in the films revealed to play a prime part on the resistivities p. Series of samples were obtained with room temperature resistivities from 14 Ω.cm to 1 mΩ.cm. The resistivity variations with T regularly evolve from a disordered semiconductor like behaviour to the bad metal behaviour of the classical superconducting NbN. The samples are highly inhomogeneous with a wide distribution of the energy barriers between conducting grains. In the high resistivity samples, thermally activated hopping is present and Ln p ∝ T-n with 1/2≤ n ≤1/4. In the less resistive samples, a percolating path is established through the lowest barriers and beyond some critical temperature T* the conductivity becomes linear in T. A superconducting transition may then appear which could be observed even on samples whose behaviour is markedly of the semiconductor type in the normal state. The highest resistivity before transition was 60 mΩ.cm. This corresponds to a resistivity ratio of 60 with respect to the value at room temperature. Application of a magnetic field up to 4 T decreases the critical temperature in the same way as for a homogeneous dirty type II superconductor

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confidence: 91%

“…Although research to improve these properties is still running [3,4], current studies are rather directed to the possible use of NbN films for Josephson junctions based integrated circuits [5][6][7]. Superconducting properties actually are greatly connected with the crystallographic structure, composition and sputtering parameters of the films [8,9].…”

mentioning

confidence: 99%

From localization to superconductivity in granular niobium nitride thin films

Cabanel¹,

Chaussy²,

Mazuer³

et al. 1988

J. Phys. France

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“…As consequence, from ref. 12, the normal state conductivity of the "nitrogen" component amounts to σ1=s1=5.5•10 5 (Ωm) -1 . With B*=20mT, as suggested by the data of Figure 1, the fitting procedure becomes straightforward: the residual resistivity ratio RRR at low field and the saturation field Bc* are the only free fitting parameters, all others are derived.…”

Section: Discussionmentioning

confidence: 99%

“…The second component of the weak superconductor is the "niobium" component, consisting of "dirty" niobium (volume fraction x2=1-x1). Depending on the concentration of nitrogen (~15 up to 25 at.%) the weak superconductor may have an intrinsic critical temperature with a lower bound of TcN~1.2-2 K [10,11,12], but, by the proximity effect, have a larger one due to the coupling with the "dirty" niobium component. TcN is the critical temperature, where the nitrogen component itself becomes a superconductor.…”

Section: Introductionmentioning

confidence: 99%

N-Doped Surfaces of Superconducting Niobium Cavities as a Disordered Composite

Weingarten

2018

IEEE Trans. Appl. Supercond.

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The Q-factor of superconducting accelerating cavities can be substantially improved by a special heat treatment under N2 atmosphere (N-doping). Recent experiments at Fermi National Laboratory investigated the dependence of Q on the RF frequency and showed, unexpectedly, both an increase and a decrease with the RF field amplitude. This paper shall explain this finding by extending a previously proposed model founded on the two fluid model of RF losses, percolation and the proximity effect in a disordered composite.

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30Mei1 - 73Kit1

Flükiger¹,

Wolf²

Nb, Nb-Al - Nb-Ge

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Propriétés et structure des couches minces de nitrure de niobium élaborées par pulvérisation cathodique réactive I. Élaboration et propriétés

Cited by 20 publications

References 12 publications

From localization to superconductivity in granular niobium nitride thin films

From localization to superconductivity in granular niobium nitride thin films

N-Doped Surfaces of Superconducting Niobium Cavities as a Disordered Composite

30Mei1 - 73Kit1

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