Property of MKID resonators using a high quality Nb film

Ryota Ito, S. Mima, Chiko Otani +3 more

Masakazu Sekine, Yutaro Sekímoto, Takashi Noguchi +6 more

Wei-Tao Lv, Liang-si Zhou, Jing Li +2 more

Microwave Kinetic Inductance Detectors (MKIDs), just like a planar resonance cavity resonating at a microwave frequency, are emerging as a kind of high-sensitivity detector suitable for large format arrays at terahertz (THz) wavelengths. There are two types of MKIDs, namely distributed (or antenna-coupled) MKIDs and lumped-element MKIDs (aka LeKIDs). Various superconducting thin films (such as Al, TiN, NbTiN, NbN, and Nb) have been investigated for MKIDs. They do work so long as the detected photon energy exceeds their energy gap, but their response and noise behaviors are yet to be fully understood. Here we report on the design, fabrication, and characterization of distributed and lumped-element MKIDs made of NbTiN superconducting film. Detailed simulation and measurement results will be presented.

Grégoire Coiffard, M. Daal, Nicholas Zobrist +4 more

Abstract Hafnium is an elemental superconductor which crystallizes in a hexagonal close packed structure, has a transition temperature T C ≃ 400 mK, and has a high normal state resistivity around 90 µ ω cm. In Microwave Kinetic Inductance Detectors (MKIDs), these properties are advantageous since they allow for creating detectors sensitive to optical and near infra-red radiation. In this work, we study how sputter conditions and especially the power applied to the target during the deposition, affect the hafnium T C , resistivity, stress, texture and preferred crystal orientation. We find that the position of the target with respect to the substrate strongly affects the orientation of the crystallites in the films and the internal quality factor, Q i , of MKIDs fabricated from the films. In particular, we demonstrate that a DC magnetron sputter deposition at a normal angle of incidence, low pressure, and low plasma power promotes the growth of compressive (002)-oriented films and that such films can be used to make high quality factor MKIDs with Q i up to 600,000.

Takashi Noguchi, Agnès Dominjon, Yutaro Sekímoto

Benjamin A. Mazin, D. Sank, Sean G. McHugh +6 more

Microwave kinetic inductance detectors, or MKIDs, are a type of low temperature detector that exhibit intrinsic frequency domain multiplexing at microwave frequencies. We present the first theory and measurements on a MKID based on a microstrip transmission line resonator. A complete characterization of the dielectric loss and noise properties of these resonators is performed, and agrees well with the derived theory. A competitive noise equivalent power of 5×10−17 W Hz−1/2 at 10 Hz has been demonstrated. The resonators exhibit the highest quality factors known in a microstrip resonator with a deposited thin film dielectric.