Measurement of loss in superconducting microstrip at millimeter-wave frequencies (original) (raw)
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The millimeter-wave properties of superconducting microstrip lines
AIP Conference Proceedings, 2002
We have developed a novel technique for making high quality measurements of the millimeter-wave properties of superconducting thin-film microstrip transmission lines. Our experimental technique currently covers the 75−130 GHz frequency range. The method is based on standing wave resonances in an open ended transmission line. We obtain information on the characteristic impedance, phase velocity, and loss of the microstrip. Our data for Nb/SiO/Nb lines, taken at 4.2 K and 1.6 K, can be explained by a single set of physical parameters, with a temperature-independent loss tangent of tan δ SiO = 1.2±0.3×10-3 for our latest samples. The amplitude 1/e attenuation length is 30 cm to 40 cm.
At millimetre wave frequencies the use of coaxial based test fixtures does not provide an accurate characterisation of planar passive or active devices. Tests using coplanar probes produce more reliable and repeatable device measurements. A suitable method to perform device characterisation is through broadband coplanar to microstrip transitions. A test bench for obtaining S-parameters up to 50 GHz is described. Calibration method and test results of passive and active circuits and devices are presented. The obtained experimental S-parameters have been used for circuit design and further integration of millimetre wave receiver systems.
Microwave and Optical Technology Letters, 2010
A contactless and nondestructive technique is employed for characterizing single-sided metallised silicon wafers. The reflection spectra are measured using a quasi-optical millmeter-wave setup in the frequency range 40–320 GHz. The results are compared with those provided by the coplanar waveguide method, in terms of accuracy and range of applicability. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2500–2505, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25524
Dielectric loss extraction for superconducting microwave resonators
Applied Physics Letters, 2020
The investigation of two-level-state (TLS) loss in dielectric materials and interfaces remains at the forefront of materials research in superconducting quantum circuits. We demonstrate a method of TLS loss extraction of a thin film dielectric by measuring a lumped element resonator fabricated from a superconductor-dielectric-superconductor trilayer. We extract the dielectric loss by formulating a circuit model for a lumped element resonator with TLS loss and then fitting to this model using measurements from a set of three resonator designs: a coplanar waveguide resonator, a lumped element resonator with an interdigitated capacitor, and a lumped element resonator with a parallel plate capacitor that includes the dielectric thin film of interest. Unlike other methods, this allows accurate measurement of materials with TLS loss lower than 10 −6. We demonstrate this method by extracting a TLS loss of 1.02 × 10 −3 for sputtered Al 2 O 3 using a set of samples fabricated from an Al/Al 2 O 3 /Al trilayer. We observe a difference of 11% between extracted loss of the trilayer with and without the implementation of this method.
Fabrication and characterization of low-loss TFMS on silicon substrate up to 220 GHz
IEEE Transactions on Microwave Theory and Techniques, 2000
This paper presents the results of the fabrication and characterization up to 220 GHz, of thin-film microstrip (TFMS) transmission-line structures. The transmission lines are fabricated on a low-resistivity silicon substrate ( = 10 cm). TFMS lines with a thick dielectric layer (20 m of benzocyclobutene is used here) present losses of 0.3 dB/mm at 94 GHz and 0.6 dB/mm at 220 GHz. Thus, using this technology, it will be possible to develop monolithic microwave integrated circuits on a silicon substrate. Index Terms-Dielectric film, low-resistivity silicon substrate, silicon, silicon monolithic microwave integrated circuits (MMICs), transmission lines.
Quasi-optical (QO) methods of dielectric spectroscopy are well established in the millimeter and submillimeter frequency bands. These methods exploit standing wave structure in the sample produced by a transmitted Gaussian beam to achieve accurate, low-noise measurement of the complex permittivity of the sample [e.g., J. A. Scales and M. Batzle, Appl. Phys. Lett. 88, 062906 (2006); R. N. Clarke and C. B. Rosenberg, J. Phys. E 15, 9 (1982); T. M. Hirovnen, P. Vainikainen, A. Lozowski, and A. V. Raisanen, IEEE Trans. Instrum. Meas. 45, 780 (1996)]. In effect the sample itself becomes a low-Q cavity. On the other hand, for optically thin samples (films of thickness much less than a wavelength) or extremely low loss samples (loss tangents below 10 −5 ) the QO approach tends to break down due to loss of signal. In such a case it is useful to put the sample in a high-Q cavity and measure the perturbation of the cavity modes. Provided that the average mode frequency divided by the shift in mode frequency is less than the Q (quality factor) of the mode, then the perturbation should be resolvable. Cavity perturbation techniques are not new, but there are technological difficulties in working in the millimeter/submillimeter wave region. In this paper we will show applications of cavity perturbation to the dielectric characterization of semi-conductor thin films of the type used in the manufacture of photovoltaics in the 100 and 350 GHz range. We measured the complex optical constants of hot-wire chemical deposition grown 1-μm thick amorphous silicon (a-Si:H) film on borosilicate glass substrate. The real part of the refractive index and dielectric constant of the glasssubstrate varies from frequency-independent to linearly frequency-dependent. We also see power-law behavior of the frequency-dependent optical conductivity from 316 GHz (9.48 cm −1 ) down to 104 GHz (3.12 cm −1 ).
Full Wave Analysis of Normal and Superconducting Microstrip Transmission Lines
Frequenz, 2010
We present a full wave analysis to compute the propagation constant of electromagnetic waves traveling in a normal and superconducting microstrip transmission line. The transverse wavenumber in the dielectric substrate is obtained as the root of a set of transcendental equation, derived by matching the tangential fields at the dielectric-conductor and dielectric-air interfaces. The propagation constant can then be obtained by substituting the transverse wavenumber into the dispersion relation. For normal microstrip lines, we found good agreement between our results and those obtained using the quasi-static methods. As compared to some of the available techniques used to calculate loss in superconducting microstrip lines, such as Maticks and Yassin-Withingtons method, our method gives higher loss especially in the regime of millimeter and submillimeter wavelengths. Since our method takes into account the superposition of TE and TM modes, we attribute the differences as due to the fringing fields effect and the existence of the longitudinal field components in our formulation.