MICROWAVE LOSSES IN KINETIC-INDUCTANCE DEVICES FABRICA lED FROM NbCN/MgO/NbCN TRILAYERS

The microwave losses in kinetic-inductance devices fabricated from niobium carbon nitride/magnesium oxide/niobium carbon nitride (NbCN/MgO/NbCN) trilayers are being investigated. For microwave applications, these devices are attractive because of the substantial reduction in size over conventional superconductor architectures while maintaining low dispersion, wide bandwidth, and acceptable superconductor losses. Except for temperatures very near the critical temperature, the performance of these devices is presently limited to quality factors between 100-500 by losses in the dielectric. While this level of loss is acceptable for some applications, reduction in the dielectric loss is needed. For this study, MgO was chosen since this material can grow epitaxially on NbCN and is consequently expected to have loss tangents closer to those of bulk crystals. In addition to the dielectric losses, the superconductor losses and other film and device parameters will be reported.