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IEEE MTT-S International Microwave Symposium digest

Bi-Layer Kinetic Inductance Detectors for W-Band

B. Aja, Luisa de la Fuente, A. Fernandez, Juan Pablo Pascual Gutiérrez, E. Artal, Marina C. de Ory, María Teresa Magaz, Daniel Granados, Jesús Martín-Pintado, A. Gómez

Published Aug 1, 2020• 12 citations
Publisher

Abstract

An array of superconducting kinetic inductance detectors (KID) has been fabricated and it has demonstrated absorption at W-Band. The use of a bi-layer structure based on aluminum (AI) and titanium (Ti) shows a lower superconducting critical temperature (Tc), which allows the detection at W-band. A design methodology is presented taking into account the KID geometry in order to maximize the absorption and a dual-polarization KID has been designed using the proposed methodology. Two prototypes of KID on Silicon substrate have been fabricated showing a good agreement between measurement and simulation results. The measurements at room temperature from 65 to 110 GHz show the matching at the frequency band, while dark cryogenic characterization demonstrated the low frequency design.

DOI
10.1109/ims30576.2020.9223828

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Dual polarization kinetic inductance detectors for large imaging cameras at millimeter wave bands

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This work deals with the development of superconducting Kinetic Inductance Detectors (KIDs) for highly sensitive radio astronomy receivers within W-band (75 to 110 GHz). A bilayer based on superconducting titanium/aluminum (Ti/Al) thin films has been used for assessing its absorption performance in this frequency band at millikelvin temperature. A lumped-element inductor based on a 4th order Hilbert structure is designed to absorb the incoming radiation in two orthogonal linear polarizations. The development of a large-format camera prototype is presented. On one hand, ambient temperature quasi-optical characterization demonstrates a suitable absorption for both polarizations within the W-band. On the other hand, dark cryogenic characterization confirms the successful operation of the multiplexed KID devices providing high-quality factors and an operation yield of 97%. These results confirm these developments to be used in future polarimeter receivers.

Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI•Jun 14, 2024•0 citations

Analysis and Performance of Lumped-Element Kinetic Inductance Detectors for W-Band

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Lumped-element superconducting resonators are a promising technology for their use in millimeter-wave observations and quantum computing applications that require large arrays of extremely sensitive detectors. Among them, lumped-element kinetic inductance detectors (LEKIDs) have shown good performance in the submillimeter band in several earth-based telescopes. In this work, LEKIDs for their use as millimeter-wave receivers of astronomical applications are presented. LEKID arrays using a thin bilayer of superconducting titanium/aluminum (Ti/Al), deposited on the silicon substrate, have been designed and fabricated. The design of a dual-polarization LEKID with the goal of detection at the W-band for two orthogonal polarizations is described and a fabricated array has demonstrated absorption at ambient temperature. Also, an approximate design methodology of the coupling parameter for LEKIDs' readout, essential for dynamic range optimization of the detector under millimeter-wave radiation, is proposed. In addition, the resonance characteristics and coupling factor of the fabricated superconducting resonators using high-quality internal factor Qiunder cryogenic temperatures have been analyzed. The design guidelines in this work are applicable to other LEKID arrays, and the presented superconducting Ti/Al thin-film LEKIDs can be used in future receiver arrays in the millimeter bands.

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We have developed and characterized an on-chip polarimeter based on Lumped Element Kinetic Inductance Detectors (LEKIDs) optimized for the whole W -band frequency range ($\mathbf{7 5 - 1 1 0} \mathbf{G H z}$). The chip consists of two$\mathbf{3} \times \mathbf{3}$LEKID arrays fabricated on opposing faces of a silicon substrate. Both arrays have been fabricated from a titanium/aluminum superconducting bilayer and they present orthogonal inductor orientations to resolve horizontal and vertical polarization modes. A second silicon substrate is coated at its rear part with an aluminum thin film and works as a back-reflector to enhance the forward absorption efficiency via constructive interference. In this work, we report the absorption response and performances in the$W$band of this on-chip polarimeter configuration in both polarizations at cryogenic temperatures. The noise spectrum and the noise equivalent power (NEP) is also characterized using a blackbody source at two different temperatures to demonstrate its functionality.

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Abstract We designed, fabricated, and characterized microwave transmission properties with rewound strip structures for YBa2Cu3O7 (YBCO)-based kinetic inductance detectors (KIDs). The superconducting rewound strip serves as a microwave resonator and as a broadband terahertz-wave antenna. To predict the microwave resonance characteristics before fabrication, the line-width (w) and space (s) dependence of the spiral resonators were analyzed using an electromagnetic simulator; the resonance frequency increased, and the quality factor decreased with increasing w and s from 10 to 40 μm. YBCO-based KID arrays with different w (10 and 40 μm) were fabricated on 10 mm-square MgO substrates, cooled to 3 K using a 4He refrigerator, and evaluated using a vector network analyzer to verify the result of the simulation experimentally. The measured resonance frequency ratio of 1.11 times (5.04 → 5.59 GHz) agreed with the simulated ones of 1.10 times (4.84 → 5.33 GHz) between w = 10 and 40 μm. The other resonance characteristics, such as transmission coefficient and quality factor, have a similar w dependence with the simulation.

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Antenna-coupled lumped-element ALD titanium nitride KIDs for CMB instruments (Conference Presentation)

Erik D. Shirokoff, Peter S. Barry, Q. Y. Tang +1 more

Future ground-based cosmic microwave background (CMB) experiments will require more than $10^5$ polarization sensitive pixels covering multiple atmospheric bands. The scientific potential for such an experiment is impressive; however, the technical challenges are daunting: such an instrument will require square meters of focal plane covered in background limited cryogenic detectors and a dramatic increase in readout capability. We are developing novel kinetic inductance detectors (KIDs) optimized for this purpose. These devices use a twin-slot microwave antenna, superconducting Nb transmission line, and a novel coupling scheme that deposits mm-wavelength power onto a high-resistivity meander deposited as the first layer on a bare Si wafer. This architecture allows us to independently adjust the detector and antenna properties and to pursue multi-band designs. We have fabricated superconducting resonators made from atomic layer deposited (ALD) titanium nitride (TiN), with thicknesses ranging from 3 to 40 nm. We find a strong dependence of transition temperature on thickness, from 0.6 to 4.2 K for our thinnest and thickest films, respectively. In dark measurements, we find internal quality factors that range from $10^4$ to $7\times 10^5$ depending on film thickness, and kinetic inductance as high as 8 nH/square. The very small volumes and high kinetic inductance make it possible to engineer extremely sensitive detectors with inductor volumes approaching a few cubic microns that operate at readout frequencies of tens to hundreds of MHz. By taking advantage of the large fractional bandwidth available at low frequencies, we expect to achieve multiplexing densities that exceed that of state of the art TES arrays even without further improvements in film quality factor. We will present the characterization of film properties and dark devices, as well as well as initial optical results for antenna coupled single-band and single-pol devices. We will also discuss designs and sensitivity projections for future dual-pol and multi-band arrays ready for deployment in near-future CMB instruments.

Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI•Jul 10, 2018•0 citations
An array of superconducting kinetic inductance detectors (KID) has been fabricated and it has demonstrated absorption at W-Band. The use of a bi-layer structure based on aluminum (AI) and titanium (Ti) shows a lower superconducting critical temperature (Tc), which allows the detection at W-band. A design methodology is presented taking into account the KID geometry in order to maximize the absorption and a dual-polarization KID has been designed using the proposed methodology. Two prototypes of KID on Silicon substrate have been fabricated showing a good agreement between measurement and simulation results. The measurements at room temperature from 65 to 110 GHz show the matching at the frequency band, while dark cryogenic characterization demonstrated the low frequency design.
This work deals with the development of superconducting Kinetic Inductance Detectors (KIDs) for highly sensitive radio astronomy receivers within W-band (75 to 110 GHz). A bilayer based on superconducting titanium/aluminum (Ti/Al) thin films has been used for assessing its absorption performance in this frequency band at millikelvin temperature. A lumped-element inductor based on a 4th order Hilbert structure is designed to absorb the incoming radiation in two orthogonal linear polarizations. The development of a large-format camera prototype is presented. On one hand, ambient temperature quasi-optical characterization demonstrates a suitable absorption for both polarizations within the W-band. On the other hand, dark cryogenic characterization confirms the successful operation of the multiplexed KID devices providing high-quality factors and an operation yield of 97%. These results confirm these developments to be used in future polarimeter receivers.
Lumped-element superconducting resonators are a promising technology for their use in millimeter-wave observations and quantum computing applications that require large arrays of extremely sensitive detectors. Among them, lumped-element kinetic inductance detectors (LEKIDs) have shown good performance in the submillimeter band in several earth-based telescopes. In this work, LEKIDs for their use as millimeter-wave receivers of astronomical applications are presented. LEKID arrays using a thin bilayer of superconducting titanium/aluminum (Ti/Al), deposited on the silicon substrate, have been designed and fabricated. The design of a dual-polarization LEKID with the goal of detection at the W-band for two orthogonal polarizations is described and a fabricated array has demonstrated absorption at ambient temperature. Also, an approximate design methodology of the coupling parameter for LEKIDs' readout, essential for dynamic range optimization of the detector under millimeter-wave radiation, is proposed. In addition, the resonance characteristics and coupling factor of the fabricated superconducting resonators using high-quality internal factor Qiunder cryogenic temperatures have been analyzed. The design guidelines in this work are applicable to other LEKID arrays, and the presented superconducting Ti/Al thin-film LEKIDs can be used in future receiver arrays in the millimeter bands.
We have developed and characterized an on-chip polarimeter based on Lumped Element Kinetic Inductance Detectors (LEKIDs) optimized for the whole W -band frequency range (75−110GHz\mathbf{7 5 - 1 1 0} \mathbf{G H z}75−110GHz). The chip consists of two3×3\mathbf{3} \times \mathbf{3}3×3LEKID arrays fabricated on opposing faces of a silicon substrate. Both arrays have been fabricated from a titanium/aluminum superconducting bilayer and they present orthogonal inductor orientations to resolve horizontal and vertical polarization modes. A second silicon substrate is coated at its rear part with an aluminum thin film and works as a back-reflector to enhance the forward absorption efficiency via constructive interference. In this work, we report the absorption response and performances in theWWWband of this on-chip polarimeter configuration in both polarizations at cryogenic temperatures. The noise spectrum and the noise equivalent power (NEP) is also characterized using a blackbody source at two different temperatures to demonstrate its functionality.
Abstract We designed, fabricated, and characterized microwave transmission properties with rewound strip structures for YBa2Cu3O7 (YBCO)-based kinetic inductance detectors (KIDs). The superconducting rewound strip serves as a microwave resonator and as a broadband terahertz-wave antenna. To predict the microwave resonance characteristics before fabrication, the line-width (w) and space (s) dependence of the spiral resonators were analyzed using an electromagnetic simulator; the resonance frequency increased, and the quality factor decreased with increasing w and s from 10 to 40 μm. YBCO-based KID arrays with different w (10 and 40 μm) were fabricated on 10 mm-square MgO substrates, cooled to 3 K using a 4He refrigerator, and evaluated using a vector network analyzer to verify the result of the simulation experimentally. The measured resonance frequency ratio of 1.11 times (5.04 → 5.59 GHz) agreed with the simulated ones of 1.10 times (4.84 → 5.33 GHz) between w = 10 and 40 μm. The other resonance characteristics, such as transmission coefficient and quality factor, have a similar w dependence with the simulation.
The complex conductivity of a superconducting thin film is related to the quasiparticle density, which depends on the physical temperature and can also be modified by external pair breaking with photons and phonons. This relationship forms the underlying operating principle of Kinetic Inductance Detectors (KIDs), where the detection threshold is governed by the superconducting energy gap. We investigate the electromagnetic properties of thin-film aluminum that is proximitized with either a normal metal layer of copper or a superconducting layer with a lowerTCT_{C}TC​, such as iridium, in order to extend the operating range of KIDs. Using the Usadel equations along with the Nam expressions for complex conductivity, we calculate the density of states and the complex conductivity of the resulting bilayers to understand the dependence of the pair breaking threshold, surface impedance, and intrinsic quality factor of superconducting bilayers on the relative film thicknesses. The calculations and analyses provide theoretical insights in designing aluminum-based bilayer kinetic inductance detectors for detection of microwave photons and athermal phonons at the frequencies well below the pair breaking threshold of a pure aluminum film.
Future ground-based cosmic microwave background (CMB) experiments will require more than 10510^5105 polarization sensitive pixels covering multiple atmospheric bands. The scientific potential for such an experiment is impressive; however, the technical challenges are daunting: such an instrument will require square meters of focal plane covered in background limited cryogenic detectors and a dramatic increase in readout capability. We are developing novel kinetic inductance detectors (KIDs) optimized for this purpose. These devices use a twin-slot microwave antenna, superconducting Nb transmission line, and a novel coupling scheme that deposits mm-wavelength power onto a high-resistivity meander deposited as the first layer on a bare Si wafer. This architecture allows us to independently adjust the detector and antenna properties and to pursue multi-band designs. We have fabricated superconducting resonators made from atomic layer deposited (ALD) titanium nitride (TiN), with thicknesses ranging from 3 to 40 nm. We find a strong dependence of transition temperature on thickness, from 0.6 to 4.2 K for our thinnest and thickest films, respectively. In dark measurements, we find internal quality factors that range from 10410^4104 to 7×1057\times 10^57×105 depending on film thickness, and kinetic inductance as high as 8 nH/square. The very small volumes and high kinetic inductance make it possible to engineer extremely sensitive detectors with inductor volumes approaching a few cubic microns that operate at readout frequencies of tens to hundreds of MHz. By taking advantage of the large fractional bandwidth available at low frequencies, we expect to achieve multiplexing densities that exceed that of state of the art TES arrays even without further improvements in film quality factor. We will present the characterization of film properties and dark devices, as well as well as initial optical results for antenna coupled single-band and single-pol devices. We will also discuss designs and sensitivity projections for future dual-pol and multi-band arrays ready for deployment in near-future CMB instruments.