Abstract
Superconducting niobium (Nb) thin films have recently attracted significant attention due to their utility for quantum information technologies. In the processing of Nb thin films, fluoride-based chemical etchants are commonly used to remove surface oxides that are known to affect superconducting quantum devices adversely. However, these same etchants can also introduce hydrogen to form Nb hydrides, potentially negatively impacting microwave loss performance. Here, comprehensive materials characterization of Nb hydrides formed in Nb thin films as a function of fluoride chemical treatments is presented. In particular, secondary-ion mass spectrometry, X-ray scattering, and transmission electron microscopy reveal the spatial distribution and phase transformation of Nb hydrides. The rate of hydride formation is determined by the fluoride solution acidity and the etch rate of Nb2O5, which acts as a diffusion barrier for hydrogen into Nb. The resulting Nb hydrides are detrimental to Nb superconducting properties and lead to increased power-independent microwave loss in coplanar waveguide resonators. However, Nb hydrides do not correlate with two-level system loss or device aging mechanisms. Overall, this work provides insight into the formation of Nb hydrides and their role in microwave loss, thus guiding ongoing efforts to maximize coherence time in superconducting quantum devices.
Original language | English (US) |
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Article number | 2401365 |
Journal | Advanced Functional Materials |
Volume | 34 |
Issue number | 36 |
DOIs | |
State | Published - Sep 4 2024 |
Funding
C.G.T.\u2010C. and D.P.G. contributed equally to this work. This work was primarily supported by the U.S. Department of Energy, the Office of Science, the National Quantum Information Science Research Centers, the Superconducting Quantum Materials and Systems Center (SQMS) under contract No. DE\u2010AC02\u201007CH11359. This work made use of the Jerome B. Cohen X\u2010Ray Diffraction Facility supported by the MRSEC program of the National Science Foundation (DMR\u20102308691) at the Materials Research Center of Northwestern University and the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS\u20101542205.) This work also made use of the EPIC and Keck\u2010II facilities of the Northwestern University NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS\u20102025633), the IIN, and the Northwestern MRSEC program (NSF DMR\u20102308691). S.M.R. also acknowledges support from the International Institute of Nanotechnology and 3M.
Keywords
- coherence
- quantum computing
- quantum information sciences
- quantum sensing
- qubit
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Chemistry
- Biomaterials
- General Materials Science
- Condensed Matter Physics
- Electrochemistry