High Quality Factor Platinum Silicide Microwave Kinetic Inductance Detectors

TL;DR

This paper introduces platinum silicide MKIDs, which outperform traditional materials like TiN and Al in sensitivity, quality factor, and quasiparticle lifetime, advancing superconducting photon detection technology.

Contribution

The study demonstrates the fabrication and characterization of high-Q platinum silicide MKIDs, showing significant improvements over existing materials in superconducting detector performance.

Findings

PtSi MKIDs have high internal quality factors ($Q_i  10^6)

They exhibit quasiparticle lifetimes of 30-40 microseconds

Spectral resolution of 8 at 406.6 nm

Abstract

We report on the development of Microwave Kinetic Inductance Detectors (MKIDs) using platinum silicide as the sensor material. MKIDs are an emerging superconducting detector technology, capable of measuring the arrival times of single photons to better than two microseconds and their energies to around ten percent. Previously, MKIDs have been fabricated using either sub-stoichiometric titanium nitride or aluminum, but TiN suffers from spatial inhomogeneities in the superconducting critical temperature and Al has a low kinetic inductance fraction, causing low detector sensitivity. To address these issues, we have instead fabricated PtSi microresonators with superconducting critical temperatures of 944$\pm$12~mK and high internal quality factors ($Q_i \gtrsim 10^6$). These devices show typical quasiparticle lifetimes of $\tau_{qp} \approx 30$--$40~\mu$s and spectral resolution, $R = \lambda / \Delta \lambda$, of 8 at 406.6~nm. We compare PtSi MKIDs to those fabricated with TiN and detail the substantial advantages that PtSi MKIDs have to offer.