Thermal stability of Mo/Au bilayers for TES applications

Parra-Borderías, María; Fernández-Martínez, Iván; Fàbrega, L.; Camón, Agustín; Gil, O.; González-Arrabal, R.; Sesé, J.; Costa‐Krämer, J. L.; Warot-Fonrose, Bénédicte; Serin, V.; Briones, F.

doi:10.1088/0953-2048/25/9/095001

Cited by 7 publications

(5 citation statements)

References 35 publications

(41 reference statements)

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“…Processing that exposes the bilayer to higher temperatures may necessitate a higher annealing temperature. It should be noted that these results are contradictory to a study published by Parra-Borderías et al where bilayer properties remained stable at temperatures up to 150 • C and significant changes in R n and T c were witnessed only at T ≥ 200 • C, attributed to an increase in Au grain size and Au migration across Mo grain boundaries at the bilayer interface [34]. evaporation conditions and initial Au grain morphology.…”

Section: Annealing To Stabilize T C and R Ncontrasting

confidence: 93%

Development of a transition-edge sensor bilayer process providing new modalities for critical temperature control

Weber

Morgan

Yan

et al. 2020

Supercond. Sci. Technol.

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Transition-edge sensors (TESs) are thermal detectors in which a superconducting film that is electrically biased in the superconducting-to-normal transition is used as a thermometer. In most TESs, the film is a superconductor-normal metal bilayer where the two materials and their thicknesses are chosen to achieve various specifications including the transition temperature Tc . Traditionally, the materials in the bilayer are deposited in sequence without breaking vacuum in order to achieve a clean, uniform bilayer interface at the wafer-scale. This approach leads to constraints in material properties, fabrication techniques and, ultimately, TES designs. To overcome these constraints, we have developed a bilayer fabrication process that allows the layers to be deposited and patterned separately with an exposure to atmosphere between the deposition steps. We demonstrate better than 6% transition-temperature uniformity across a 7.6 cm (3 in) substrate and present satisfactory spectra from TES x-ray detectors fabricated in this fashion. We show how the new hybrid additive-subtractive TES fabrication process creates new design possibilities, including broad tuning of Tc across a substrate with a single bilayer thickness.

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Section: Annealing To Stabilize T C and R Ncontrasting

confidence: 93%

Development of a transition-edge sensor bilayer process providing new modalities for critical temperature control

Weber

Morgan

Yan

et al. 2020

Supercond. Sci. Technol.

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“…Au initially grows following Mo columns, with average grain size 20 nm at the interface. As the thickness of the gold layer increases the grain size and its dispersion increase, up to 70-100 nm on average [6,14]. Thus, the thickest Au layers studied in this work display column widths of the order of 100 nm and increasing disorder.…”

Section: Methodsmentioning

confidence: 68%

Exploring the Proximity Effect in Mo/Au Bilayers

Fàbrega

Camón

Strichovanec

et al. 2019

IEEE Trans. Appl. Supercond.

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We report on the sensitivity of superconducting transition temperature (Tc) to the individual layers' thickness in Mo/Au proximity bilayers to be used in Transition-Edge Sensors. The achieved good reproducibility and quality of the bilayers allow a clear determination of the superconducting critical temperature Tc as a function of the Mo and Au thicknesses. One objective of this work is to analyse the quality of the Mo-Au interface and to assess the possible effects of the double Au layer we use to fabricate these bilayers and TESs based on them. Experimental data are analysed on the base of Usadel equations using the model developed by Martinis and co-workers, in which the proximity effect in the bilayer is mainly governed by the interface transparency between the superconductor and the normal metal. We find that this model describes quite well the behaviour of Tc, even for quite thick Au layers, and that the double Au layer does not play any relevant role on the proximity effect.

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“…Typical thicknesses to obtain T c~1 00mK are 60nm/215nm. These bilayers have been shown 13 to be stable when heated up to a temperature of 150ºC, which guarantees that they will meet any thermal qualification tests. 10,12 , producing in a rather simple way the banks that have been demonstrated essential to obtain sharp and reproducible transitions 14 .…”

Section: Tes Fabricationmentioning

confidence: 99%

“…In previous work we demonstrated our ability to fabricate high quality, reproducible Mo thin films and Mo-based TES 10,11,12,13 . Now we have devised a development plan aimed at fabricating TES meeting X-IFU requirements.…”

Section: Introductionmentioning

confidence: 99%

Towards Mo/Au based TES detectors for Athena/X-IFU

et al. 2014

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The X-ray spectroscopy telescope Athena has been designed to implement the science theme "the hot and energetic universe", selected by the European Space Agency as the second large mission of its Cosmic Vision program. X-IFU, one of the two interchangeable focal plane instruments of Athena, is a high resolution X-ray spectrometer made of a large array of Transition Edge Sensors. Two options are under consideration for the X-IFU microcalorimeters: Ti/Au bilayers or Mo/Au bilayers. Here we report on our efforts to develop Mo/Au-based TES. The TES are made of high quality superconducting Mo/Au bilayers fabricated at room temperature on low stress Si 3 N 4 membranes; Mo is deposited by RF magnetron sputtering and in-situ covered by a thin (15nm) Au layer deposited by DC sputtering; in a second step, the Au layer thickness is increased ex-situ by e-beam deposition, to obtain suitable resistance R n and operation temperature values. Very sharp transitions (~few mK transition width) are obtained, with typically R n~2 5mΩ and T c~ 100-120mK for 65/215 bilayers. First simple TES designs are being tested. Also, Bi films several μm thick, intended to constitute the X-ray absorber, are fabricated by electrochemical deposition.

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Thermal stability of Mo/Au bilayers for TES applications

Cited by 7 publications

References 35 publications

Development of a transition-edge sensor bilayer process providing new modalities for critical temperature control

Development of a transition-edge sensor bilayer process providing new modalities for critical temperature control

Exploring the Proximity Effect in Mo/Au Bilayers

Towards Mo/Au based TES detectors for Athena/X-IFU

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