Superconductivity in the system MoxCyGazOδ prepared by focused ion beam induced deposition

Weirich, P. M.; Schwalb, Christian H.; Winhold, Marcel; Huth, Michael

doi:10.1063/1.4874657

Cited by 8 publications

(9 citation statements)

References 19 publications

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“…In particular, due to the amorphous character of the material, it is unclear which role played is by the gallium atoms in formation of the superconducting state. This issue applies to the whole family of amorphous superconductors grown by FIBID using a gallium source. ,, In contrast, the origin of superconductivity in the nanowires investigated here is clearly to be attributed to the formation of NbC nanocrystallites. During the fabrication process, the gallium ions generate a cascade of secondary electrons, which are responsible for the decomposition of the precursor.…”

Section: Resultsmentioning

confidence: 81%

“…Other superconductor materials, i.e. , C–Ga–O and Mo–Ga–C–O nanocomposites, with T c values of 7 and 3.8 K, respectively, were prepared by FIBID with the precursors phenanthrene (C 14 H 10 ) and Mo(CO) 6 . , Moreover, gallium-free superconducting nanostructures were recently fabricated by helium ion microscopy (HIM) and FEBID by using W(CO) 6 , , Mo(CO) 6 in the presence of water, and (CH 3 CH 2 ) 4 Pb, with T c values between 2 and 7.2 K. One notes that the majority of these materials are amorphous superconductors with a high degree of disorder, which limits their application because statistical fluctuations of the order parameter can lead to spatial variations of T c . , …”

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confidence: 99%

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Crystalline Niobium Carbide Superconducting Nanowires Prepared by Focused Ion Beam Direct Writing

et al. 2019

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Superconducting planar nanostructures are widely used in applications, e.g., for highly sensitive magnetometers and in basic research, e.g., to study finite size effects or vortex dynamics. In contrast, 3D superconducting nanostructures, despite their potential in quantum information processing and nanoelectronics, have been addressed only in a few pioneering experiments. This is due to the complexity of fabricating 3D nanostructures by conventional techniques such as electron-beam lithography and to the scarce number of superconducting materials available for direct-writing techniques, which enable the growth of 3D free-standing nanostructures. Here, we present a comparative study of planar nanowires and free-standing 3D nanowires fabricated by focused electron-and ion (Ga+)-beam induced deposition (FEBID and FIBID) using the precursor Nb(NMe 2 ) 3 (N-t-Bu). FEBID nanowires contain about 67 atomic percent C, 22 atomic percent N, and 11 atomic percent Nb, while FIBID samples are composed of 43 atomic percent C, 13 atomic percent N, 15.5 atomic percent Ga, and 28.5 atomic percent Nb. Transmission electron microscopy shows that FEBID samples are amorphous, while FIBID samples exhibit a fcc NbC polycrystalline structure, with grains about 15−20 nm in diameter. Electrical transport measurements show that FEBID nanowires are highly resistive following a variable-range-hopping behavior. In contradistinction, FIBID planar nanowires become superconducting at T c ≈ 5 K. In addition, the critical temperature of free-standing 3D nanowires is as high as T c ≈ 11 K, which is close to the value of bulk NbC. In conclusion, FIBID-NbC is a promising material for the fabrication of superconducting nanowire single-photon detectors (SNSPD) and for the development of 3D superconductivity with applications in quantum information processing and nanoelectronics.

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Section: Resultsmentioning

confidence: 81%

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confidence: 99%

Crystalline Niobium Carbide Superconducting Nanowires Prepared by Focused Ion Beam Direct Writing

et al. 2019

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“…Specifically, the FIBID deposition parameters were optimized for the precursor Mo(CO) 6 . In this case, the GA did not only optimize the conductance of the molybdenum-based FIBID structures, moreover, the deposits were found to be superconducting with tunable superconducting transition temperatures from which the highest T c of 3.8 K was observed for the GA-optimized sample [43]. Future work regarding the GA will be especially directed towards FEBID binary systems.…”

Section: Resultsmentioning

confidence: 96%

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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“…Its weakcoupling BCS-like behavior was confirmed in tunneling spectroscopy [65] and it was used in studies relating to vortex matter [66], in spin-polarized An-dreev reflection experiments with ferromagnetic counter electrodes prepared by FEBID [67] and in studies on induced odd-frequency triplet pairing in superconductor-ferromagnet proximity junctions [68,69]. By using different precursors other superconducting materials prepared by Ga-FIBID were discovered, such as Mo-Ga-C-O with the precursor Mo(CO) 6 [70], showing a maximum T c of 3. [71].…”

Section: As-grown Febid Superconductorsmentioning

confidence: 92%

Focused electron beam induced deposition meets materials science

Huth

Porrati

Dobrovolskiy

2018

Microelectronic Engineering

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157

172

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simulation-assisted growth of complex three-dimensional nano-architectures is also covered. In the review particular emphasis is laid on conceptual clarity in the description of the different developments, which is reflected in the mostly schematic nature of the presented figures, as well as in the recurring final sub-sections for each of the main topics discussing the respective "challenges and perspectives".

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Superconductivity in the system MoxCyGazOδ prepared by focused ion beam induced deposition

Cited by 8 publications

References 19 publications

Crystalline Niobium Carbide Superconducting Nanowires Prepared by Focused Ion Beam Direct Writing

Crystalline Niobium Carbide Superconducting Nanowires Prepared by Focused Ion Beam Direct Writing

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

Focused electron beam induced deposition meets materials science

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