Fabrication and characterization of low-loss Al/Si/Al parallel plate capacitors for superconducting quantum information applications

Abstract Increasing the density of superconducting circuits requires compact components, however, superconductor-based capacitors typically perform worse as dimensions are reduced due to loss at surfaces and interfaces. Here, parallel plate capacitors composed of aluminum-contacted, crystalline sili...

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Main Authors: Anthony P. McFadden, Aranya Goswami, Tongyu Zhao, Teun van Schijndel, Trevyn F. Q. Larson, Sudhir Sahu, Stephen Gill, Florent Lecocq, Raymond Simmonds, Chris Palmstrøm
Format: Article
Language:English
Published: Nature Portfolio 2025-01-01
Series:npj Quantum Information
Online Access:https://doi.org/10.1038/s41534-025-00967-5
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author Anthony P. McFadden
Aranya Goswami
Tongyu Zhao
Teun van Schijndel
Trevyn F. Q. Larson
Sudhir Sahu
Stephen Gill
Florent Lecocq
Raymond Simmonds
Chris Palmstrøm
author_facet Anthony P. McFadden
Aranya Goswami
Tongyu Zhao
Teun van Schijndel
Trevyn F. Q. Larson
Sudhir Sahu
Stephen Gill
Florent Lecocq
Raymond Simmonds
Chris Palmstrøm
author_sort Anthony P. McFadden
collection DOAJ
description Abstract Increasing the density of superconducting circuits requires compact components, however, superconductor-based capacitors typically perform worse as dimensions are reduced due to loss at surfaces and interfaces. Here, parallel plate capacitors composed of aluminum-contacted, crystalline silicon fins are shown to be a promising technology for use in superconducting circuits by evaluating the performance of lumped element resonators and transmon qubits. High aspect ratio Si-fin capacitors having widths below 300 nm with an approximate total height of 3 μm are fabricated using anisotropic wet etching of Si(110) substrates followed by aluminum metallization. The single-crystal Si capacitors are incorporated in lumped element resonators and transmons by shunting them with lithographically patterned aluminum inductors and conventional A l/A l O x /A l Josephson junctions respectively. Microwave characterization of these devices suggests state-of-the-art performance for superconducting parallel plate capacitors with low power internal quality factor of lumped element resonators greater than 500 k and qubit T 1 times greater than 25 μs. These results suggest that Si-Fins are a promising technology for applications that require low-loss, compact, superconductor-based capacitors with minimal stray capacitance.
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spelling doaj-art-1afff2c7e7fc453fac6e004667570bec2025-08-20T02:49:35ZengNature Portfolionpj Quantum Information2056-63872025-01-011111610.1038/s41534-025-00967-5Fabrication and characterization of low-loss Al/Si/Al parallel plate capacitors for superconducting quantum information applicationsAnthony P. McFadden0Aranya Goswami1Tongyu Zhao2Teun van Schijndel3Trevyn F. Q. Larson4Sudhir Sahu5Stephen Gill6Florent Lecocq7Raymond Simmonds8Chris Palmstrøm9National Institute of Standards and TechnologyDepartment of Electrical and Computer Engineering, University of CaliforniaNational Institute of Standards and TechnologyDepartment of Electrical and Computer Engineering, University of CaliforniaNational Institute of Standards and TechnologyNational Institute of Standards and TechnologyNational Institute of Standards and TechnologyNational Institute of Standards and TechnologyNational Institute of Standards and TechnologyDepartment of Electrical and Computer Engineering, University of CaliforniaAbstract Increasing the density of superconducting circuits requires compact components, however, superconductor-based capacitors typically perform worse as dimensions are reduced due to loss at surfaces and interfaces. Here, parallel plate capacitors composed of aluminum-contacted, crystalline silicon fins are shown to be a promising technology for use in superconducting circuits by evaluating the performance of lumped element resonators and transmon qubits. High aspect ratio Si-fin capacitors having widths below 300 nm with an approximate total height of 3 μm are fabricated using anisotropic wet etching of Si(110) substrates followed by aluminum metallization. The single-crystal Si capacitors are incorporated in lumped element resonators and transmons by shunting them with lithographically patterned aluminum inductors and conventional A l/A l O x /A l Josephson junctions respectively. Microwave characterization of these devices suggests state-of-the-art performance for superconducting parallel plate capacitors with low power internal quality factor of lumped element resonators greater than 500 k and qubit T 1 times greater than 25 μs. These results suggest that Si-Fins are a promising technology for applications that require low-loss, compact, superconductor-based capacitors with minimal stray capacitance.https://doi.org/10.1038/s41534-025-00967-5
spellingShingle Anthony P. McFadden
Aranya Goswami
Tongyu Zhao
Teun van Schijndel
Trevyn F. Q. Larson
Sudhir Sahu
Stephen Gill
Florent Lecocq
Raymond Simmonds
Chris Palmstrøm
Fabrication and characterization of low-loss Al/Si/Al parallel plate capacitors for superconducting quantum information applications
npj Quantum Information
title Fabrication and characterization of low-loss Al/Si/Al parallel plate capacitors for superconducting quantum information applications
title_full Fabrication and characterization of low-loss Al/Si/Al parallel plate capacitors for superconducting quantum information applications
title_fullStr Fabrication and characterization of low-loss Al/Si/Al parallel plate capacitors for superconducting quantum information applications
title_full_unstemmed Fabrication and characterization of low-loss Al/Si/Al parallel plate capacitors for superconducting quantum information applications
title_short Fabrication and characterization of low-loss Al/Si/Al parallel plate capacitors for superconducting quantum information applications
title_sort fabrication and characterization of low loss al si al parallel plate capacitors for superconducting quantum information applications
url https://doi.org/10.1038/s41534-025-00967-5
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