Surface oxide formation dynamics of tantalum

Alpha-phase tantalum has emerged as the leading material candidate for superconducting circuits [1]. Its resilience to aggressive surface cleaning protocols ompared to Nb and Al, coupled with a thin, stoichiometric surface oxide structure, leads to reduced losses [2]. The remaining surface losses are dominated by interfacial two-level systems (TLS) located in the native surface oxide [3]. Therefore, it is imperative to study the dynamics of surface oxide growth for tantalum. In this talk, we present X-ray photoemission spectroscopy (XPS) results to characterize the native oxide. We evaluate the impact various chemical processing and ambient exposure conditions have on its formation, and we explore methods for processing and controlling the oxide.



[1] Place, Alexander PM, et al., Nature Communications 12.1 (2021): 1779

[2] McLellan, Russell A., et al., Advanced Science 10.21 (2023): 2300921

[3] Crowley, Kevin D., et al., Physical Review X 13.4 (2023): 041005