@article{614adee5c18b4eb9814ff2272969fcdb,
title = "Chemical Profiles of the Oxides on Tantalum in State of the Art Superconducting Circuits",
abstract = "Over the past decades, superconducting qubits have emerged as one of the leading hardware platforms for realizing a quantum processor. Consequently, researchers have made significant effort to understand the loss channels that limit the coherence times of superconducting qubits. A major source of loss has been attributed to two level systems that are present at the material interfaces. It is recently shown that replacing the metal in the capacitor of a transmon with tantalum yields record relaxation and coherence times for superconducting qubits, motivating a detailed study of the tantalum surface. In this work, the chemical profile of the surface of tantalum films grown on c-plane sapphire using variable energy X-ray photoelectron spectroscopy (VEXPS) is studied. The different oxidation states of tantalum that are present in the native oxide resulting from exposure to air are identified, and their distribution through the depth of the film is measured. Furthermore, it is shown how the volume and depth distribution of these tantalum oxidation states can be altered by various chemical treatments. Correlating these measurements with detailed measurements of quantum devices may elucidate the underlying microscopic sources of loss.",
keywords = "X-ray photoelectron spectroscopy, dielectric loss, oxide, qubits, superconducting thin films, tantalum",
author = "McLellan, {Russell A.} and Aveek Dutta and Chenyu Zhou and Yichen Jia and Conan Weiland and Xin Gui and Place, {Alexander P.M.} and Crowley, {Kevin D.} and Le, {Xuan Hoang} and Trisha Madhavan and Youqi Gang and Lukas Baker and Head, {Ashley R.} and Iradwikanari Waluyo and Ruoshui Li and Kim Kisslinger and Adrian Hunt and Ignace Jarrige and Lyon, {Stephen A.} and Barbour, {Andi M.} and Cava, {Robert J.} and Houck, {Andrew A.} and Hulbert, {Steven L.} and Mingzhao Liu and Walter, {Andrew L.} and {de Leon}, {Nathalie P.}",
note = "Funding Information: R.A.M and A.D. contributed equally to this work. The authors acknowledge Mayer Feldman for support with tantalum depositions and Esha Umbarkar for sample preparation. The authors also acknowledge Denis Potapenko for support with the XPS system in the Princeton Imaging and Analysis Center. This material was based upon work primarily supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Co‐design Center for Quantum Advantage (CQA) under contract number DE‐SC0012704. Film characterization and processing was partly supported by the National Science Foundation (RAISE DMR‐1839199). This research used resources of the Spectroscopy Soft and Tender Beamlines (SST‐1 and SST‐2) of the National Synchrotron Light Source II and the Electron Microscopy and Materials Synthesis & Characterization facilities of the Center for Functional Nanomaterials (CFN), U.S. Department of Energy Office of Science Facilities at Brookhaven National Laboratory under contract no. DE‐SC0012704. The authors acknowledge the use of Princeton's Imaging and Analysis Center (IAC), which is partially supported by the Princeton Center for Complex Materials (PCCM), the National Science Foundation (NSF) Materials Research Science and Engineering Center (MRSEC; DMR‐2011750). Some chemical treatments were performed in the Princeton Institute for the Science and Technology of Materials (PRISM) cleanroom. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships Program (SULI). 2 Funding Information: R.A.M and A.D. contributed equally to this work. The authors acknowledge Mayer Feldman for support with tantalum depositions and Esha Umbarkar for sample preparation. The authors also acknowledge Denis Potapenko for support with the XPS system in the Princeton Imaging and Analysis Center. This material was based upon work primarily supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Co-design Center for Quantum Advantage (C2QA) under contract number DE-SC0012704. Film characterization and processing was partly supported by the National Science Foundation (RAISE DMR-1839199). This research used resources of the Spectroscopy Soft and Tender Beamlines (SST-1 and SST-2) of the National Synchrotron Light Source II and the Electron Microscopy and Materials Synthesis & Characterization facilities of the Center for Functional Nanomaterials (CFN), U.S. Department of Energy Office of Science Facilities at Brookhaven National Laboratory under contract no. DE-SC0012704. The authors acknowledge the use of Princeton's Imaging and Analysis Center (IAC), which is partially supported by the Princeton Center for Complex Materials (PCCM), the National Science Foundation (NSF) Materials Research Science and Engineering Center (MRSEC; DMR-2011750). Some chemical treatments were performed in the Princeton Institute for the Science and Technology of Materials (PRISM) cleanroom. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships Program (SULI). Publisher Copyright: {\textcopyright} 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.",
year = "2023",
month = jul,
day = "27",
doi = "10.1002/advs.202300921",
language = "English (US)",
volume = "10",
journal = "Advanced Science",
issn = "2198-3844",
publisher = "Wiley-VCH Verlag",
number = "21",
}