Superconductivity in sputtered rhenium films on silicon

In order to maximize the coherence times of superconducting qubits, it is necessary to investigate materials platforms that consist of high-quality superconducting thin films on low-loss substrates. Recently, the adoption of tantalum as a leading material for superconducting circuits has prompted the investigation of other refractory metals as candidates to yield low-loss devices. At the same time, the use of silicon as a substrate is of continued interest due to its low loss tangent and its ability to be micromachined for advanced circuit architectures. While rhenium devices fabricated on sapphire have been characterized, the investigation of rhenium on silicon remains largely unexplored. In this talk, we report superconductivity in sputtered rhenium films on silicon and observe the superconducting transition through electrical measurements. We characterize the interfaces of these films and find that, unlike commonly used superconducting films, they exhibit sub-nanometer metal-air and metal-substrate interfaces. Finally, we realize microwave resonators with quality factors exceeding a million at single-photon power. This suggests that this materials platform could lead to lower dielectric losses and higher coherence times in superconducting quantum technologies.