(Invited) Atomic Layer Deposition of Superconductors

Proslier, Thomas; Klug, Jeffrey A.; Becker, Nicholas; Elam, Jeffrey W.; Pellin, Michael J.

doi:10.1149/1.3633673

Cited by 20 publications

(20 citation statements)

References 6 publications

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“…From this composition analysis, the origin of the low Tc (< 3 K) before annealing could be correlated with the absence of carbon in our films. This correlates with the results obtained by Proslier et al where the NbN films grown from NbCl 5 (i.e., carbonfree films) also exhibit a Tc value below 3 K[11]. The carbon enhanced the Tc and, based on…”

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confidence: 91%

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Improved critical temperature of superconducting plasma-enhanced atomic layer deposition of niobium nitride thin films by thermal annealing

et al. 2020

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The efficiency of the superconducting radio frequency cavities composed of Nb required the deposition of thickness-controlled multilayer coatings of superconductor-insulator-superconductor (S-IS) on the internal surfaces of the cavities. Herein, we report the plasma-enhanced atomic layer deposition of carbon-free NbN (50 µm thick), followed by a thermal treatment, to obtain the superconducting layer in the S-IS structure. Using (tert-butylimido)-tris(diethylamino)-niobium as the niobium precursor and H 2 and NH 3 plasma as reactive gases, the deposition and annealing parameters were optimized by studying their effects on the film properties (crystallinity, density, and composition). We demonstrated that the superconducting critical temperature (Tc) can be improved after thermal annealing up to 13.8 K, a value compatible with the targeted application. In addition to the expected densified layers and increased grain size, we observed a partial transformation of the oxide present in the as-deposited layer into niobium oxynitride, which could indicate the origin of the improvement of the superconducting properties. With low carbon and oxygen impurity concentrations in the films, this study contributes to the understanding of the relationship between the structure, composition, and superconductivity in NbN.

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confidence: 91%

“…improved the superconducting critical temperature (Tc) from 4 K to 7.5 K [11]. Nevertheless, the reducing power of the reactive gases like NH 3 used in thermal ALD is insufficient to obtain stoichiometric nitrides from a metal precursor [12].…”

Section: Introductionmentioning

confidence: 99%

Improved critical temperature of superconducting plasma-enhanced atomic layer deposition of niobium nitride thin films by thermal annealing

et al. 2020

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“…This highly controllable process provides superior thickness and stoichiometric uniformity and an atomically smooth surface 18,19 as compared to chemical vapor deposition, the standard technique used to grow NbTiN films 20 . We used NbCl 5 , TiCl 4 , and NH 3 as gaseous reactants; the stoichiometry was tuned by varying the ratio of TiCl 4 /NbCl 5 cycles during growth 21 . The superconducting properties of these ultrathin NbTiN films were optimized by utilizing AlN buffer layers grown on top of the Si substrate 22 .…”

Section: Samples Preparation and Characterizationmentioning

confidence: 99%

Superconducting phase transitions in disordered NbTiN films

Burdastyh

Postolova

Proslier

et al. 2020

Sci Rep

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The suppression of superconductivity in disordered systems is a fundamental problem of condensed matter physics. Here we investigate the superconducting niobium-titanium-nitride (Nb 1−x TixN) thin films grown by atomic layer deposition (ALD) where disorder is controlled by the slight tuning of the ALD process parameters. We observe the smooth crossover from the disorderdriven superconductor-normal metal transition (often reffered to as fermionic mechanism) to the case where bosonic mechanism dominates and increasing disorder leads to formation of metal with Cooper pairing. We show that, in 'moderately' disordered films, the transition to zero-resistance state occurs in a full agreement with the conventional theories of superconducting fluctuations and Berezinskii-Kosterlitz-Thouless transition. However, the 'critically' disordered films violate this accord showing low-temperature features possibly indicating the Bose metal phase. We show that it is the interrelation between film's sheet resistance in the maximum, Rmax, of the resistive curve R✷(T ) and Rq = h/4e 2 that distinguishes between these two behaviors. We reveal the characteristic features in magnetoresistance of the 'critically' disordered films with Rmax > Rq. 2/9

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“…This highly controllable process provides superior thickness and stoichiometric uniformity and an atomically smooth surface 25 , 26 as compared to chemical vapor deposition, the standard technique used to grow NbTiN films 27 . We used NbCl 5 , TiCl 4 , and NH 3 as gaseous reactants; the stoichiometry was tuned by varying the ratio of TiCl 4 /NbCl 5 cycles during growth 28 . The superconducting properties of these ultrathin NbTiN films were optimized by utilizing AlN buffer layers grown on top of the Si substrate 29 .…”

Section: Sample Preparationmentioning

confidence: 99%

Charge Berezinskii-Kosterlitz-Thouless transition in superconducting NbTiN films

Mironov

Silevitch

Proslier

et al. 2018

Sci Rep

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Three decades after the prediction of charge-vortex duality in the critical vicinity of the two-dimensional superconductor-insulator transition (SIT), one of the fundamental implications of this duality—the charge Berezinskii-Kosterlitz-Thouless (BKT) transition that should occur on the insulating side of the SIT—has remained unobserved. The dual picture of the process points to the existence of a superinsulating state endowed with zero conductance at finite temperature. Here, we report the observation of the charge BKT transition on the insulating side of the SIT in 10 nm thick NbTiN films, identified by the BKT critical behavior of the temperature and magnetic field dependent resistance, and map out the magnetic-field dependence of the critical temperature of the charge BKT transition. Finally, we ascertain the effects of the finite electrostatic screening length and its divergence at the magnetic field-tuned approach to the superconductor-insulator transition.

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(Invited) Atomic Layer Deposition of Superconductors

Cited by 20 publications

References 6 publications

Improved critical temperature of superconducting plasma-enhanced atomic layer deposition of niobium nitride thin films by thermal annealing

Improved critical temperature of superconducting plasma-enhanced atomic layer deposition of niobium nitride thin films by thermal annealing

Superconducting phase transitions in disordered NbTiN films

Charge Berezinskii-Kosterlitz-Thouless transition in superconducting NbTiN films

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