Impact of Growth Conditions on Material Properties and Superconducting Resonator Losses Using Sputtered Ta and Nb Films

In recent years, Ta and Nb thin films have been used to fabricate high-coherence superconducting qubits. It has been observed that qubit and resonator losses are impacted by the quality of these films and their interfaces, making the use of well-tuned growth conditions instrumental for achieving high coherence times. In this work, we systematically compare Ta and Nb films deposited by RF sputtering using different growth conditions and materials analysis tools. We pattern microwave resonators with different geometries and measure them in a dilution refrigerator to obtain their single-photon quality factors and model the losses. This study contributes to understanding the relation between growth conditions, material and interface properties, and microwave losses in superconducting Ta and Nb films.