Measured quality factor and intermodulation product of CPW resonators on silicon substrates with 100 nm wide niobium lines at 17 GHz and 4.2 K

Abstract

Superconducting resonators with symmetrical coplanar wave guides (CPWs) have been simulated and measured near 17 GHz at 4.2 K. The inner conductor width, thickness and length are about 100 nm×250 nm×3.2 mm , respectively. Both ground lines are 500 nm wide. CPW tapers with 100 Ω characteristic impedance yield the transition from small to large cross-sections for coaxial SMA connectors. All coplanar conductors are implemented with niobium on 375 μm thick silicon wafers. The measured and simulated quality factor and resonance frequency are in good agreement, as the kinetic inductances are taken into account. Present measured results may be extrapolated to niobium structures below 100 nm with quality factors in the order of 100, more than two orders of magnitudes larger than with aluminium at 4.2 K.