Zr-Ti-N alloys for superconducting resonators

Zr-Ti-N is a promising material system for future superconducting devices and circuits. Alloying enables a range of lattice constants that can be matched to several insulating nitride materials to grow epitaxial Josephson Junctions. The associated range of critical temperatures between 5 K and 10 K may also enable superconducting bandgap engineering in order to control quasiparticle dynamics.

Epitaxial ZrN, TiN, and ZrTiN alloys are grown on Al₂O₃ (0001), Si (001) and Si (111) wafers with plasma-assisted molecular beam epitaxy. These thin films are characterized using RHEED, HRXRD, AFM, SEM and cryogenic transport. Additionally, quarter-wave coplanar waveguide resonators are used to assess the microwave loss and kinetic inductance.