Focused-ion-beam-induced deposition of superconducting nanowires

Sadki, E. S.; Ooi, S.; Hirata, Kazuto

doi:10.1063/1.1842367

Cited by 143 publications

(195 citation statements)

References 42 publications

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“…At this point it is worth mentioning that the conductivity can be further increased by employing focused ion beam induced deposition (FIBID) in combination with the precursor W(CO) 6 . Metallic tungsten-based FIBID structures which are also known to become superconducting below 5.2 K, [34][35][36][37] exhibit conductivity values up to 400-680 kS/m exceeding the values for tungsten-based FEBID structures reported here by a factor of 30-50 [34,36,38]. The difference of conductivity between samples prepared by means of FEBID and FIBID is, however, not inherent to deposits fabricated by the dissociation of W(CO) 6 .…”

Section: Resultsmentioning

confidence: 70%

Identifying the crossover between growth regimes via in-situ conductance measurements in focused electron beam induced deposition

Winhold¹,

Weirich²,

Schwalb³

et al. 2014

Nanofabrication

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Focused electron beam induced deposition presents a promising technique for the fabrication of nanostructures. However, due to the dissociation of mostly organometallic precursor molecules employed for the deposition process, prepared nanostructures contain organic residues leading to rather low conductance of the deposits. Post-growth treatment of the structures by electron irradiation or in reactive atmospheres at elevated temperatures can be applied to purify the samples. Recently, an in-situ conductance optimization process involving evolutionary genetic algorithm techniques has been introduced leading to an increase of conductance by one order of magnitude for tungsten-based deposits using the precursor W(CO)6. This method even allows for the optimization of conductance of nano-structures for which post-growth treatment is not possible or desirable. However, the mechanisms responsible for the observed enhancement have not been studied in depth. In this work, we identified the dwell-time dependent change of conductivity of the samples to be the major contributor to the change of conductance. Specifically, the chemical composition drastically changes with a variation of dwelltime resulting in an increase of the metal content by 15 at% for short dwell-times. The relative change of growth rate amounts to less than 25 % and has a negligible influence on conductance. We anticipate the in-situ genetic algorithm optimization procedure to be of high relevance for new developments regarding binary or ternary systems prepared by focused electron or ion beam induced deposition.

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Section: Resultsmentioning

confidence: 70%

Identifying the crossover between growth regimes via in-situ conductance measurements in focused electron beam induced deposition

Winhold¹,

Weirich²,

Schwalb³

et al. 2014

Nanofabrication

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show abstract

“…Disordered or granular W films alloys show significant T c enhancements [3]. The superconductivity of FIB-deposited tungsten was first demonstrated by Sadki et al [4] then by Luxmoore et al [5]. Both groups reported a Tc of 5.2 K for such material and qualitatively ascribe the comparatively high Tc to the absence of long-range order in the material crystal structure.…”

Section: Introductionmentioning

confidence: 92%

Focused-Ion-Beam Direct-Writing of Ultra-Thin Superconducting Tungsten Composite Films

Fenton

Warburton

2009

IEEE Trans. Appl. Supercond.

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Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Abstract-Tungsten composite films of thickness as low as 19 nm have been deposited using a 30 keV Ga + focused-ion-beam with tungsten carboxyl (W(CO) 6 ) as the gas precursor. Films of thickness 25 nm or more are superconducting with a transition temperature exceeding 5 K. Films in the thickness range 25 nm to 50 nm show an increasing T c for a decreasing film thickness. This correlates well with the measured dependence of the normal state resistivity upon film thickness. We attribute this behavior to an increase in the BCS electron-phonon interaction potential resulting from a reduction in the electron mean-free-path as the film thickness is reduced. In the light of these data we discuss the applicability of FIB-deposited tungsten for devices requiring ultra-thin superconducting films, including photon detectors and phase-slip qubits.

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“…It has been shown that the resulting deposit is superconducting with T c around 5 K (ref. 27). The precursor gas was injected into the process chamber by means of a needle inserted in the vicinity of the specimen, around 50 mm away in x-y direction and around 150 mm away in the z direction of the substrate surface.…”

Section: Methodsmentioning

confidence: 99%

Magnetic field-induced dissipation-free state in superconducting nanostructures

et al. 2013

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A superconductor in a magnetic field acquires a finite electrical resistance caused by vortex motion. A quest to immobilize vortices and recover zero resistance at high fields made intense studies of vortex pinning one of the mainstreams of superconducting research. Yet, the decades of efforts resulted in a realization that even promising nanostructures, utilizing vortex matching, cannot withstand high vortex density at large magnetic fields. Here, we report a giant reentrance of vortex pinning induced by increasing magnetic field in a W-based nanowire and a TiN-perforated film densely populated with vortices. We find an extended range of zero resistance with vortex motion arrested by self-induced collective traps. The latter emerge due to order parameter suppression by vortices confined in narrow constrictions by surface superconductivity. Our findings show that geometric restrictions can radically change magnetic properties of superconductors and reverse detrimental effects of magnetic field.

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Focused-ion-beam-induced deposition of superconducting nanowires

Cited by 143 publications

References 42 publications

Identifying the crossover between growth regimes via in-situ conductance measurements in focused electron beam induced deposition

Identifying the crossover between growth regimes via in-situ conductance measurements in focused electron beam induced deposition

Focused-Ion-Beam Direct-Writing of Ultra-Thin Superconducting Tungsten Composite Films

Magnetic field-induced dissipation-free state in superconducting nanostructures

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