Tungsten silicide films for microwave kinetic inductance detectors

TL;DR

This paper investigates tungsten silicide alloys W5Si3 and WSi2 for use in microwave kinetic inductance detectors, demonstrating their tunable critical temperature, high resistivity, and promising superconducting properties for detector applications.

Contribution

It introduces tungsten silicide alloys as new materials for MKIDs, with detailed measurements of their superconducting and electrical properties.

Findings

W5Si3 and WSi2 alloys have tunable critical temperatures.

They exhibit high normal-state resistivity and large kinetic inductance fractions.

Superconducting resonators made from these alloys show promising performance.

Abstract

Microwave Kinetic Inductance Detectors (MKIDs) provide highly multiplexed arrays of detectors that can be configured to operate from the sub-millimeter to the X-ray regime. We have examined two tungsten silicide alloys (W5Si3 and WSi2), which are dense alloys that provide a critical temperature tunable with composition, large kinetic inductance fraction, and high normal-state resistivity. We have fabricated superconducting resonators and provide measurement data on critical temperature, surface resistance, quality factor, noise, and quasiparticles lifetime. Tungsten silicide appears to be promising for microwave kinetic inductance detectors.