1
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Xue R, Beer M, Seidler I, Humpohl S, Tu JS, Trellenkamp S, Struck T, Bluhm H, Schreiber LR. Si/SiGe QuBus for single electron information-processing devices with memory and micron-scale connectivity function. Nat Commun 2024; 15:2296. [PMID: 38485971 PMCID: PMC10940717 DOI: 10.1038/s41467-024-46519-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 02/26/2024] [Indexed: 03/18/2024] Open
Abstract
The connectivity within single carrier information-processing devices requires transport and storage of single charge quanta. Single electrons have been adiabatically transported while confined to a moving quantum dot in short, all-electrical Si/SiGe shuttle device, called quantum bus (QuBus). Here we show a QuBus spanning a length of 10 μm and operated by only six simply-tunable voltage pulses. We introduce a characterization method, called shuttle-tomography, to benchmark the potential imperfections and local shuttle-fidelity of the QuBus. The fidelity of the single-electron shuttle across the full device and back (a total distance of 19 μm) is (99.7 ± 0.3) %. Using the QuBus, we position and detect up to 34 electrons and initialize a register of 34 quantum dots with arbitrarily chosen patterns of zero and single-electrons. The simple operation signals, compatibility with industry fabrication and low spin-environment-interaction in 28Si/SiGe, promises long-range spin-conserving transport of spin qubits for quantum connectivity in quantum computing architectures.
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Affiliation(s)
- Ran Xue
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Max Beer
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Inga Seidler
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Simon Humpohl
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
- ARQUE Systems GmbH, Aachen, Germany
| | - Jhih-Sian Tu
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, Jülich, Germany
| | - Stefan Trellenkamp
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, Jülich, Germany
| | - Tom Struck
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
- ARQUE Systems GmbH, Aachen, Germany
| | - Hendrik Bluhm
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
- ARQUE Systems GmbH, Aachen, Germany
| | - Lars R Schreiber
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany.
- ARQUE Systems GmbH, Aachen, Germany.
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2
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Struck T, Volmer M, Visser L, Offermann T, Xue R, Tu JS, Trellenkamp S, Cywiński Ł, Bluhm H, Schreiber LR. Spin-EPR-pair separation by conveyor-mode single electron shuttling in Si/SiGe. Nat Commun 2024; 15:1325. [PMID: 38351007 PMCID: PMC10864332 DOI: 10.1038/s41467-024-45583-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 01/29/2024] [Indexed: 02/16/2024] Open
Abstract
Long-ranged coherent qubit coupling is a missing function block for scaling up spin qubit based quantum computing solutions. Spin-coherent conveyor-mode electron-shuttling could enable spin quantum-chips with scalable and sparse qubit-architecture. Its key feature is the operation by only few easily tuneable input terminals and compatibility with industrial gate-fabrication. Single electron shuttling in conveyor-mode in a 420 nm long quantum bus has been demonstrated previously. Here we investigate the spin coherence during conveyor-mode shuttling by separation and rejoining an Einstein-Podolsky-Rosen (EPR) spin-pair. Compared to previous work we boost the shuttle velocity by a factor of 10000. We observe a rising spin-qubit dephasing time with the longer shuttle distances due to motional narrowing and estimate the spin-shuttle infidelity due to dephasing to be 0.7% for a total shuttle distance of nominal 560 nm. Shuttling several loops up to an accumulated distance of 3.36 μm, spin-entanglement of the EPR pair is still detectable, giving good perspective for our approach of a shuttle-based scalable quantum computing architecture in silicon.
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Affiliation(s)
- Tom Struck
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
- ARQUE Systems GmbH, Aachen, Germany
| | - Mats Volmer
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Lino Visser
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Tobias Offermann
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Ran Xue
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Jhih-Sian Tu
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, Jülich, Germany
| | - Stefan Trellenkamp
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, Jülich, Germany
| | - Łukasz Cywiński
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | - Hendrik Bluhm
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
- ARQUE Systems GmbH, Aachen, Germany
| | - Lars R Schreiber
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany.
- ARQUE Systems GmbH, Aachen, Germany.
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3
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Kutovyi Y, Jansen MM, Qiao S, Falter C, von den Driesch N, Brazda T, Demarina N, Trellenkamp S, Bennemann B, Grützmacher D, Pawlis A. Efficient Single-Photon Sources Based on Chlorine-Doped ZnSe Nanopillars with Growth Controlled Emission Energy. ACS Nano 2022; 16:14582-14589. [PMID: 36095839 DOI: 10.1021/acsnano.2c05045] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Isolated impurity states in epitaxially grown semiconductor systems possess important radiative features such as distinct wavelength emission with a very short radiative lifetime and low inhomogeneous broadening, which make them promising for the generation of indistinguishable single photons. In this study, we investigate chlorine-doped ZnSe/ZnMgSe quantum well (QW) nanopillar (NP) structures as a highly efficient solid-state single-photon source operating at cryogenic temperatures. We show that single photons are generated due to the radiative recombination of excitons bound to neutral Cl atoms in ZnSe QW and the energy of the emitted photon can be tuned from about 2.85 down to 2.82 eV with ZnSe well width increase from 2.7 to 4.7 nm. Following the developed advanced technology, we fabricate NPs with a diameter of about 250 nm using a combination of dry and wet-chemical etching of epitaxially grown ZnSe/ZnMgSe QW structures. The remaining resist mask serves as a spherical- or cylindrical-shaped solid immersion lens on top of NPs and leads to the emission intensity enhancement by up to an order of magnitude in comparison to the pillars without any lenses. NPs with spherical-shaped lenses show the highest emission intensity values. The clear photon-antibunching effect is confirmed by the measured value of the second-order correlation function at a zero time delay of 0.14. The developed single-photon sources are suitable for integration into scalable photonic circuits.
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Affiliation(s)
- Yurii Kutovyi
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, 52074 Aachen, Germany
| | - Marvin Marco Jansen
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, 52074 Aachen, Germany
| | - Siqi Qiao
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, 52074 Aachen, Germany
| | - Christine Falter
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, 52074 Aachen, Germany
| | - Nils von den Driesch
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, 52074 Aachen, Germany
| | - Thorsten Brazda
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, 52074 Aachen, Germany
| | - Nataliya Demarina
- Peter Grünberg Institute (PGI-2), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Stefan Trellenkamp
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Benjamin Bennemann
- Peter Grünberg Institute (PGI-10), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Detlev Grützmacher
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Alexander Pawlis
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, 52074 Aachen, Germany
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4
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Schmitt TW, Connolly MR, Schleenvoigt M, Liu C, Kennedy O, Chávez-Garcia JM, Jalil AR, Bennemann B, Trellenkamp S, Lentz F, Neumann E, Lindström T, de Graaf SE, Berenschot E, Tas N, Mussler G, Petersson KD, Grützmacher D, Schüffelgen P. Integration of Topological Insulator Josephson Junctions in Superconducting Qubit Circuits. Nano Lett 2022; 22:2595-2602. [PMID: 35235321 DOI: 10.1021/acs.nanolett.1c04055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The integration of semiconductor Josephson junctions (JJs) in superconducting quantum circuits provides a versatile platform for hybrid qubits and offers a powerful way to probe exotic quasiparticle excitations. Recent proposals for using circuit quantum electrodynamics (cQED) to detect topological superconductivity motivate the integration of novel topological materials in such circuits. Here, we report on the realization of superconducting transmon qubits implemented with (Bi0.06Sb0.94)2Te3 topological insulator (TI) JJs using ultrahigh vacuum fabrication techniques. Microwave losses on our substrates, which host monolithically integrated hardmasks used for the selective area growth of TI nanostructures, imply microsecond limits to relaxation times and, thus, their compatibility with strong-coupling cQED. We use the cavity-qubit interaction to show that the Josephson energy of TI-based transmons scales with their JJ dimensions and demonstrate qubit control as well as temporal quantum coherence. Our results pave the way for advanced investigations of topological materials in both novel Josephson and topological qubits.
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Affiliation(s)
- Tobias W Schmitt
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
- JARA-Institute for Green IT, Peter Grünberg Institute 10, Forschungszentrum Jülich and RWTH Aachen University, 52062 Aachen, Germany
| | - Malcolm R Connolly
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1H 0AH, United Kingdom
| | - Michael Schleenvoigt
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
| | - Chenlu Liu
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Oscar Kennedy
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1H 0AH, United Kingdom
| | - José M Chávez-Garcia
- Microsoft Quantum Lab Copenhagen and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Abdur R Jalil
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
| | - Benjamin Bennemann
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
| | - Stefan Trellenkamp
- Helmholtz Nano Facility, Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Florian Lentz
- Helmholtz Nano Facility, Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Elmar Neumann
- Helmholtz Nano Facility, Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Tobias Lindström
- National Physical Laboratory, Teddington TW11 0LW, United Kingdom
| | | | - Erwin Berenschot
- MESA+ Institute, University of Twente, 7500AE Enschede, The Netherlands
| | - Niels Tas
- MESA+ Institute, University of Twente, 7500AE Enschede, The Netherlands
| | - Gregor Mussler
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
| | - Karl D Petersson
- Microsoft Quantum Lab Copenhagen and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Detlev Grützmacher
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
- JARA-Institute for Green IT, Peter Grünberg Institute 10, Forschungszentrum Jülich and RWTH Aachen University, 52062 Aachen, Germany
| | - Peter Schüffelgen
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
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5
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Möller S, Banszerus L, Knothe A, Steiner C, Icking E, Trellenkamp S, Lentz F, Watanabe K, Taniguchi T, Glazman LI, Fal'ko VI, Volk C, Stampfer C. Probing Two-Electron Multiplets in Bilayer Graphene Quantum Dots. Phys Rev Lett 2021; 127:256802. [PMID: 35029428 DOI: 10.1103/physrevlett.127.256802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 11/01/2021] [Indexed: 05/21/2023]
Abstract
We report on finite bias spectroscopy measurements of the two-electron spectrum in a gate defined bilayer graphene (BLG) quantum dot for varying magnetic fields. The spin and valley degree of freedom in BLG give rise to multiplets of six orbital symmetric and ten orbital antisymmetric states. We find that orbital symmetric states are lower in energy and separated by ≈ 0.4-0.8 meV from orbital antisymmetric states. The symmetric multiplet exhibits an additional energy splitting of its six states of ≈ 0.15-0.5 meV due to lattice scale interactions. The experimental observations are supported by theoretical calculations, which allow to determine that intervalley scattering and "current-current" interaction constants are of the same magnitude in BLG.
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Affiliation(s)
- S Möller
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - A Knothe
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
| | - C Steiner
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - E Icking
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - S Trellenkamp
- Helmholtz Nano Facility, Forschungszentrum Jülich, Jülich 52425, Germany
| | - F Lentz
- Helmholtz Nano Facility, Forschungszentrum Jülich, Jülich 52425, Germany
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - L I Glazman
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - V I Fal'ko
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Henry Royce Institute for Advanced Materials, University of Manchester, Manchester M13 9PL, United Kingdom
| | - C Volk
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
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6
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Banszerus L, Möller S, Steiner C, Icking E, Trellenkamp S, Lentz F, Watanabe K, Taniguchi T, Volk C, Stampfer C. Spin-valley coupling in single-electron bilayer graphene quantum dots. Nat Commun 2021; 12:5250. [PMID: 34475394 PMCID: PMC8413270 DOI: 10.1038/s41467-021-25498-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/13/2021] [Indexed: 11/30/2022] Open
Abstract
Understanding how the electron spin is coupled to orbital degrees of freedom, such as a valley degree of freedom in solid-state systems, is central to applications in spin-based electronics and quantum computation. Recent developments in the preparation of electrostatically-confined quantum dots in gapped bilayer graphene (BLG) enable to study the low-energy single-electron spectra in BLG quantum dots, which is crucial for potential spin and spin-valley qubit operations. Here, we present the observation of the spin-valley coupling in bilayer graphene quantum dots in the single-electron regime. By making use of highly-tunable double quantum dot devices we achieve an energy resolution allowing us to resolve the lifting of the fourfold spin and valley degeneracy by a Kane-Mele type spin-orbit coupling of ≈ 60 μeV. Furthermore, we find an upper limit of a potentially disorder-induced mixing of the \documentclass[12pt]{minimal}
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\begin{document}$$K^{\prime}$$\end{document}K′ states below 20 μeV. Understanding the interaction between spin and valley degrees of freedom in graphene-based quantum dots underpins their applications in electronics and quantum information. Here, the authors study the low-energy spectrum and resolve the spin-valley coupling in single-electron quantum dots in bilayer graphene.
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Affiliation(s)
- L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen, Germany. .,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany.
| | - S Möller
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - C Steiner
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - E Icking
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - S Trellenkamp
- Helmholtz Nano Facility, Forschungszentrum Jülich, Jülich, Germany
| | - F Lentz
- Helmholtz Nano Facility, Forschungszentrum Jülich, Jülich, Germany
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - C Volk
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
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7
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Rosenbach D, Schmitt TW, Schüffelgen P, Stehno MP, Li C, Schleenvoigt M, Jalil AR, Mussler G, Neumann E, Trellenkamp S, Golubov AA, Brinkman A, Grützmacher D, Schäpers T. Reappearance of first Shapiro step in narrow topological Josephson junctions. Sci Adv 2021; 7:7/26/eabf1854. [PMID: 34162537 PMCID: PMC8221618 DOI: 10.1126/sciadv.abf1854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 05/12/2021] [Indexed: 06/13/2023]
Abstract
In Josephson junctions, a supercurrent across a nonsuperconducting weak link is carried by electron-hole bound states. Because of the helical spin texture of nondegenerate topological surface states, gapless bound states are established in junctions with topological weak link. These have a characteristic 4π-periodic current phase relation (CΦR) that leads to twice the conventional Shapiro step separation voltage in radio frequency-dependent measurements. In this context, we identify an attenuated first Shapiro step in (Bi0.06Sb0.94)2Te3 (BST) Josephson junctions with AlO x capping layer. We further investigate junctions on narrow, selectively deposited BST nanoribbons, where surface charges are confined to the perimeter of the nanoribbon. Within these junctions, previously identified signatures of gapless bound states are absent. Because of confinement, transverse momentum sub-bands are quantized and a topological gap opening is observed. Surface states within these quantized sub-bands are spin degenerate, which evokes bound states of conventional 2π-periodic CΦR within the BST nanoribbon weak link.
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Affiliation(s)
- Daniel Rosenbach
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany.
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, Aachen, Germany
| | - Tobias W Schmitt
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-FIT Institute Green IT, RWTH Aachen University, 52062 Aachen, Germany
| | - Peter Schüffelgen
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Martin P Stehno
- Physikalisches Institut EP3, University of Würzburg, Am Hubland 97070, Würzburg, Germany
| | - Chuan Li
- MESA+ Institute for Nanotechnology, University of Twente, 7500AE Enschede, The Netherlands
| | - Michael Schleenvoigt
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Abdur R Jalil
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Gregor Mussler
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Elmar Neumann
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Stefan Trellenkamp
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Alexander A Golubov
- MESA+ Institute for Nanotechnology, University of Twente, 7500AE Enschede, The Netherlands
| | - Alexander Brinkman
- MESA+ Institute for Nanotechnology, University of Twente, 7500AE Enschede, The Netherlands
| | - Detlev Grützmacher
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Thomas Schäpers
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, Aachen, Germany
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8
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Mikulics M, Sofer Z, Winden A, Trellenkamp S, Förster B, Mayer J, Hardtdegen HH. Nano-LED induced chemical reactions for structuring processes. Nanoscale Adv 2020; 2:5421-5427. [PMID: 36132052 PMCID: PMC9418560 DOI: 10.1039/d0na00851f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 10/19/2020] [Indexed: 06/12/2023]
Abstract
We present a structuring technique based on the initialization of chemical reactions by an array of nano-LEDs which is used in the near-field as well as in the far-field regime. In the near-field regime, we demonstrate first results with the nano-LED array for lithography using the photoresist DiazoNaphthoQuinone-(DNQ)-sulfonate for the fabrication of holes in the resist down to ∼75 nanometres in diameter. In contrast, the nano-LEDs can also be employed in the far-field regime to expose thin films of the monomer bisphenol A-glycidyl methacrylate (Bis-GMA) and to initialize polymerization locally. Photosensitive films were patterned and spherical cone-shaped three dimensional objects with diameters ranging from ∼480 nm up to 20 micrometres were obtained. The modification in the material as a result of the photochemical reaction induced i.e. by polymerization was confirmed by Raman spectroscopy. This structuring maskless technique has the potential to induce substantial changes in photosensitive molecules and to produce the desired structures from the tens of microns down to the nanometre scale.
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Affiliation(s)
- Martin Mikulics
- Ernst Ruska Zentrum (ER-C-2), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
- Jülich-Aachen Research Alliance, JARA, Fundamentals of Future Information Technology 52425 Jülich Germany
| | - Zdenĕk Sofer
- Department of Inorganic Chemistry, Institute of Chemical Technology Technická 5 Prague 6 Czech Republic
| | | | - Stefan Trellenkamp
- Helmholtz Nanoelectronic Facility (HNF), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
| | - Beate Förster
- Jülich-Aachen Research Alliance, JARA, Fundamentals of Future Information Technology 52425 Jülich Germany
- Ernst Ruska Zentrum (ER-C-1), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
| | - Joachim Mayer
- Ernst Ruska Zentrum (ER-C-2), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
- Jülich-Aachen Research Alliance, JARA, Fundamentals of Future Information Technology 52425 Jülich Germany
| | - Hilde Helen Hardtdegen
- Ernst Ruska Zentrum (ER-C-2), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
- Jülich-Aachen Research Alliance, JARA, Fundamentals of Future Information Technology 52425 Jülich Germany
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9
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Banszerus L, Rothstein A, Fabian T, Möller S, Icking E, Trellenkamp S, Lentz F, Neumaier D, Watanabe K, Taniguchi T, Libisch F, Volk C, Stampfer C. Electron-Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots. Nano Lett 2020; 20:7709-7715. [PMID: 32986437 PMCID: PMC7564435 DOI: 10.1021/acs.nanolett.0c03227] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/28/2020] [Indexed: 05/21/2023]
Abstract
Electron and hole Bloch states in bilayer graphene exhibit topological orbital magnetic moments with opposite signs, which allows for tunable valley-polarization in an out-of-plane magnetic field. This property makes electron and hole quantum dots (QDs) in bilayer graphene interesting for valley and spin-valley qubits. Here, we show measurements of the electron-hole crossover in a bilayer graphene QD, demonstrating opposite signs of the magnetic moments associated with the Berry curvature. Using three layers of top gates, we independently control the tunneling barriers while tuning the occupation from the few-hole regime to the few-electron regime, crossing the displacement-field-controlled band gap. The band gap is around 25 meV, while the charging energies of the electron and hole dots are between 3 and 5 meV. The extracted valley g-factor is around 17 and leads to opposite valley polarization for electrons and holes at moderate B-fields. Our measurements agree well with tight-binding calculations for our device.
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Affiliation(s)
- L. Banszerus
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
| | - A. Rothstein
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
| | - T. Fabian
- Institute
for Theoretical Physics, TU Wien, 1040 Vienna, Austria, E.U
| | - S. Möller
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
| | - E. Icking
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
| | - S. Trellenkamp
- Helmholtz
Nano Facility, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - F. Lentz
- Helmholtz
Nano Facility, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - D. Neumaier
- AMO
GmbH, Gesellschaft für
Angewandte Mikro- und Optoelektronik, 52074 Aachen, Germany, E.U
- University
of Wuppertal, 42285 Wuppertal, Germany, E.U
| | - K. Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - T. Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - F. Libisch
- Institute
for Theoretical Physics, TU Wien, 1040 Vienna, Austria, E.U
| | - C. Volk
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
| | - C. Stampfer
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
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10
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Schümmer A, Mertins HC, Schneider CM, Adam R, Trellenkamp S, Borowski R, Bürgler DE, Juschkin L, Berges U. A scanning reflection X-ray microscope for magnetic imaging in the EUV range. J Synchrotron Radiat 2019; 26:2040-2049. [PMID: 31721749 DOI: 10.1107/s1600577519012219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 09/03/2019] [Indexed: 06/10/2023]
Abstract
The mechanical setup of a novel scanning reflection X-ray microscope is presented. It is based on zone plate optics optimized for reflection mode in the EUV spectral range. The microscope can operate at synchrotron radiation beamlines as well as at laboratory-based plasma light sources. In contrast to established X-ray transmission microscopes that use thin foil samples, the new microscope design presented here allows the investigation of any type of bulk materials. Importantly, this permits the investigation of magnetic materials by employing experimental techniques based on X-ray magnetic circular dichroism, X-ray linear magnetic dichroism or the transversal magneto-optical Kerr effect (T-MOKE). The reliable functionality of the new microscope design has been demonstrated by T-MOKE microscopy spectra of Fe/Cr-wedge/Fe trilayer samples. The spectra were recorded at various photon energies across the Fe 3p edge revealing the orientation of magnetic domains in the sample.
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Affiliation(s)
| | - H Ch Mertins
- FH-Münster, Stegerwaldstraße 39, 48565 Steinfurt, Germany
| | | | - Roman Adam
- Forschungszenrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | | | - Rene Borowski
- Forschungszenrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | | | - Larissa Juschkin
- Forschungszenrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | - Ulf Berges
- Zentrum für Synchrotronstrahlung DELTA, Maria-Goeppert-Mayer-Straße, 44227 Dortmund, Germany
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11
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Schüffelgen P, Rosenbach D, Li C, Schmitt TW, Schleenvoigt M, Jalil AR, Schmitt S, Kölzer J, Wang M, Bennemann B, Parlak U, Kibkalo L, Trellenkamp S, Grap T, Meertens D, Luysberg M, Mussler G, Berenschot E, Tas N, Golubov AA, Brinkman A, Schäpers T, Grützmacher D. Selective area growth and stencil lithography for in situ fabricated quantum devices. Nat Nanotechnol 2019; 14:825-831. [PMID: 31358942 DOI: 10.1038/s41565-019-0506-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 06/14/2019] [Indexed: 06/10/2023]
Abstract
The interplay of Dirac physics and induced superconductivity at the interface of a 3D topological insulator (TI) with an s-wave superconductor (S) provides a new platform for topologically protected quantum computation based on elusive Majorana modes. To employ such S-TI hybrid devices in future topological quantum computation architectures, a process is required that allows for device fabrication under ultrahigh vacuum conditions. Here, we report on the selective area growth of (Bi,Sb)2Te3 TI thin films and stencil lithography of superconductive Nb for a full in situ fabrication of S-TI hybrid devices via molecular-beam epitaxy. A dielectric capping layer was deposited as a final step to protect the delicate surfaces of the S-TI hybrids at ambient conditions. Transport experiments in as-prepared Josephson junctions show highly transparent S-TI interfaces and a missing first Shapiro step, which indicates the presence of Majorana bound states. To move from single junctions towards complex circuitry for future topological quantum computation architectures, we monolithically integrated two aligned hardmasks to the substrate prior to growth. The presented process provides new possibilities to deliberately combine delicate quantum materials in situ at the nanoscale.
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Affiliation(s)
- Peter Schüffelgen
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany.
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, Jülich, Germany.
| | - Daniel Rosenbach
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, Jülich, Germany
| | - Chuan Li
- MESA+ Institute, University of Twente, Enschede, The Netherlands
| | - Tobias W Schmitt
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
- JARA-FIT Institute Green IT, RWTH Aachen University, Aachen, Germany
| | - Michael Schleenvoigt
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | - Abdur R Jalil
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | - Sarah Schmitt
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | - Jonas Kölzer
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | - Meng Wang
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, Jülich, Germany
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China
| | - Benjamin Bennemann
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | - Umut Parlak
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | - Lidia Kibkalo
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | | | - Thomas Grap
- Institute of Semiconductor Electronics, RWTH Aachen University, Aachen, Germany
| | - Doris Meertens
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | - Martina Luysberg
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
| | - Gregor Mussler
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, Jülich, Germany
| | - Erwin Berenschot
- MESA+ Institute, University of Twente, Enschede, The Netherlands
| | - Niels Tas
- MESA+ Institute, University of Twente, Enschede, The Netherlands
| | | | | | - Thomas Schäpers
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, Jülich, Germany
| | - Detlev Grützmacher
- Peter Grünberg Institute, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany
- Helmholtz Virtual Institute for Topological Insulators (VITI), Forschungszentrum Jülich, Jülich, Germany
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12
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Weyrich C, Lanius M, Schüffelgen P, Rosenbach D, Mussler G, Bunte S, Trellenkamp S, Grützmacher D, Schäpers T. Phase-coherent transport in selectively grown topological insulator nanodots. Nanotechnology 2019; 30:055201. [PMID: 30499462 DOI: 10.1088/1361-6528/aaee5f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Oxidized Si(111) substrates were pre-structured by electron beam lithography and used as a substrate for the selective growth of three-dimensional topological insulators (TI) by molecular beam epitaxy. The patterned holes were filled up by the TI, i.e. Sb2Te3 and Bi2Te3, to form nanodots. Scanning electron microscopy and focused ion beam cross-sectioning was utilized to determine the morphology and depth profile of the nanodots. The magnetotransport measurements revealed universal conductance fluctuations originating from electron interference in phase-coherent loops. We find that these loops are oriented preferentially within the quintuple layers of the TI with only a small perpendicular contribution. Furthermore, we found clear indications of an conductivity anisotropy between different crystal orientations.
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Affiliation(s)
- Christian Weyrich
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, D-52425 Jülich, Germany. JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Germany
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13
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Schümmer A, Mertins HC, Schneider CM, Adam R, Trellenkamp S, Borowski R, Juschkin L, Berges U. Fast and easy fabrication methodology of Fresnel zone plates for the extreme ultraviolet and soft x-ray regions. Appl Opt 2019; 58:1057-1063. [PMID: 30874156 DOI: 10.1364/ao.58.001057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 12/22/2018] [Indexed: 06/09/2023]
Abstract
Zone plate design and efficient methods for the fabrication of zone plates for extreme ultraviolet (EUV) and soft x-ray applications in a newly developed scanning reflection microscope are presented. Based on e-beam lithography, three types of transmission zone plates with focal lengths between 6 and 15 mm are reported: (i) phase-shifting zone plates made by 190 nm thick PMMA rings on Si3N4 membranes, (ii) absorbing zone plates made by 75 nm thick Au ring structures on Si3N4, and (iii) freestanding Au rings of 50 nm thickness and increased transmission in the EUV range. Experiments at the DELTA synchrotron facility reveal a minimum spot size and resulting spatial resolution of 9±3 μm, which is the theoretical limit resulting from the synchrotron beam parameters at 60 eV photon energy. Images of a Ti/Si chessboard test pattern are recorded exploiting the energy dependence of the element-specific reflectance.
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14
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Jin J, Stoica T, Trellenkamp S, Chen Y, Anttu N, Migunov V, Kawabata RMS, Buenconsejo PJS, Lam YM, Haas F, Hardtdegen H, Grützmacher D, Kardynał BE. Dense, Regular GaAs Nanowire Arrays by Catalyst-Free Vapor Phase Epitaxy for Light Harvesting. ACS Appl Mater Interfaces 2016; 8:22484-22492. [PMID: 27504951 DOI: 10.1021/acsami.6b05581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Density dependent growth and optical properties of periodic arrays of GaAs nanowires (NWs) by fast selective area growth MOVPE are investigated. As the period of the arrays is decreased from 500 nm down to 100 nm, a volume growth enhancement by a factor of up to four compared with the growth of a planar layer is observed. This increase is explained as resulting from increased collection of precursors on the side walls of the nanowires due to the gas flow redistribution in the space between the NWs. Normal spectral reflectance of the arrays is strongly reduced compared with a flat substrate surface in all fabricated arrays. Electromagnetic modeling reveals that this reduction is caused by antireflective action of the nanowire arrays and nanowire-diameter dependent light absorption. Irrespective of the periodicity and diameter, Raman scattering and grazing angle X-ray diffraction show signal from zinc blende and wurtzite phases, the latter originating from stacking faults as observed by high resolution transmission electron microscopy. Raman spectra contain intense surface phonons peaks, whose intensity depends strongly on the nanowire diameters as a result of potential structural changes and as well as variations of optical field distribution in the nanowires.
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Affiliation(s)
- Jiehong Jin
- Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Toma Stoica
- Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany
- National Institute of Materials Physics , P.O. Box MG-7, Magurele, Bucharest 077125, Romania
| | - Stefan Trellenkamp
- Peter Grünberg Institute 8 (PGI 8) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Yang Chen
- Division of Solid State Physics and NanoLund, Lund University , Box 118, 22100 Lund, Sweden
| | - Nicklas Anttu
- Division of Solid State Physics and NanoLund, Lund University , Box 118, 22100 Lund, Sweden
| | - Vadim Migunov
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute , Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rudy M S Kawabata
- Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Pio J S Buenconsejo
- Materials Science and Engineering, Nanyang Technological University , 639798 Singapore
| | - Yeng M Lam
- Materials Science and Engineering, Nanyang Technological University , 639798 Singapore
| | - Fabian Haas
- Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Hilde Hardtdegen
- Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Detlev Grützmacher
- Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Beata E Kardynał
- Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany
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15
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Engels S, Weber P, Terrés B, Dauber J, Meyer C, Volk C, Trellenkamp S, Wichmann U, Stampfer C. Fabrication of coupled graphene-nanotube quantum devices. Nanotechnology 2013; 24:035204. [PMID: 23263231 DOI: 10.1088/0957-4484/24/3/035204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report on the fabrication and characterization of all-carbon hybrid quantum devices based on graphene and single-walled carbon nanotubes. We discuss both carbon nanotube quantum dot devices with graphene charge detectors and nanotube quantum dots with graphene leads. The devices are fabricated by chemical vapor deposition growth of carbon nanotubes and subsequent structuring of mechanically exfoliated graphene. We study the detection of individual charging events in the carbon nanotube quantum dot by a nearby graphene nanoribbon and show that they lead to changes of up to 20% of the conductance maxima in the graphene nanoribbon, acting as a well performing charge detector. Moreover, we discuss an electrically coupled graphene-nanotube junction, which exhibits a tunneling barrier with tunneling rates in the low GHz regime. This allows us to observe Coulomb blockade on a carbon nanotube quantum dot with graphene source and drain leads.
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Affiliation(s)
- S Engels
- II Institute of Physics B, RWTH Aachen University, D-52074 Aachen, EU, Germany.
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16
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Manheller M, Trellenkamp S, Waser R, Karthäuser S. Reliable fabrication of 3 nm gaps between nanoelectrodes by electron-beam lithography. Nanotechnology 2012; 23:125302. [PMID: 22414820 DOI: 10.1088/0957-4484/23/12/125302] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The reliable fabrication of nanoelectrode pairs with predefined separations in the few nanometer range is an essential prerequisite for future nanoelectronic devices. Here we demonstrate a fine-tuned electron-beam lithographic (EBL) fabrication route which is suitable for defining nanoelectrode pairs with a gap size down to 3 ± 1 nm and with a yield of 55%. This achievement is based on an optimized two-layer resist system in combination with an adopted developer system, as well as on an elaborated nanoelectrode pattern design taking into consideration the EBL inherent proximity effect. Thus, even a structural control in the nanometer scale is achieved in the EBL process.
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Affiliation(s)
- Marcel Manheller
- Peter-Grünberg Institut and JARA-FIT, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
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17
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Volk C, Fringes S, Terrés B, Dauber J, Engels S, Trellenkamp S, Stampfer C. Electronic excited states in bilayer graphene double quantum dots. Nano Lett 2011; 11:3581-3586. [PMID: 21805985 DOI: 10.1021/nl201295s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report tunneling spectroscopy experiments on a bilayer graphene double quantum dot device that can be tuned by all-graphene lateral gates. The diameter of the two quantum dots are around 50 nm and the constrictions acting as tunneling barriers are 30 nm in width. The double quantum dot features additional energies on the order of 20 meV. Charge stability diagrams allow us to study the tunable interdot coupling energy as well as the spectrum of the electronic excited states on a number of individual triple points over a large energy range. The obtained constant level spacing of 1.75 meV over a wide energy range is in good agreement with the expected single-particle energy spacing in bilayer graphene quantum dots. Finally, we investigate the evolution of the electronic excited states in a parallel magnetic field.
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Affiliation(s)
- C Volk
- JARA-FIT and II. Institute of Physics B, RWTH Aachen University, 52074 Aachen, Germany
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18
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Habicht S, Zhao QT, Feste SF, Knoll L, Trellenkamp S, Ghyselen B, Mantl S. Electrical characterization of strained and unstrained silicon nanowires with nickel silicide contacts. Nanotechnology 2010; 21:105701. [PMID: 20154367 DOI: 10.1088/0957-4484/21/10/105701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present electrical characterization of nickel monosilicide (NiSi) contacts formed on strained and unstrained silicon nanowires (NWs), which were fabricated by top-down processing of initially As(+) implanted and activated strained and unstrained silicon-on-insulator (SOI) substrates. The resistivity of doped Si NWs and the contact resistivity of the NiSi to Si NW contacts are studied as functions of the As(+) ion implantation dose and the cross-sectional area of the wires. Strained silicon NWs show lower resistivity for all doping concentrations due to their enhanced electron mobility compared to the unstrained case. An increase in resistivity with decreasing cross section of the NWs was observed for all implantation doses. This is ascribed to the occurrence of dopant deactivation. Comparing the silicidation of uniaxially tensile strained and unstrained Si NWs shows no difference in silicidation speed and in contact resistivity between NiSi/Si NW. Contact resistivities as low as 1.2 x 10(-8) Omega cm(-2) were obtained for NiSi contacts to both strained and unstrained Si NWs. Compared to planar contacts, the NiSi/Si NW contact resistivity is two orders of magnitude lower.
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Affiliation(s)
- S Habicht
- Institute of Bio- and Nanosystems, Forschungszentrum Jülich and JARA-Fundamentals of Future Information Technology, D-52425 Jülich, Germany
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19
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Yi Z, Trellenkamp S, Offenhäusser A, Mayer D. Molecular junctions based on intermolecular electrostatic coupling. Chem Commun (Camb) 2010; 46:8014-6. [DOI: 10.1039/c0cc02201b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wensorra J, Lepsa MI, Trellenkamp S, Moers J, Indlekofer KM, Lüth H. Gate-controlled quantum collimation in nanocolumn resonant tunneling transistors. Nanotechnology 2009; 20:465402. [PMID: 19844000 DOI: 10.1088/0957-4484/20/46/465402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Nanoscaled resonant tunneling transistors (RTT) based on MBE-grown GaAs/AlAs double-barrier quantum well (DBQW) structures have been fabricated by a top-down approach using electron-beam lithographic definition of the vertical nanocolumns. In the preparation process, a reproducible mask alignment accuracy of below 10 nm has been achieved and the all-around metal gate at the level of the DBQW structure has been positioned at a distance of about 20 nm relative to the semiconductor nanocolumn. Due to the specific doping profile n++/i/n++ along the transistor nanocolumn, a particular confining potential is established for devices with diameters smaller than 70 nm, which causes a collimation effect of the propagating electrons. Under these conditions, room temperature optimum performance of the nano-RTTs is achieved with peak-to-valley current ratios above 2 and a peak current swing factor of about 6 for gate voltages between -6 and +6 V. These values indicate that our nano-RTTs can be successfully used in low power fast nanoelectronic circuits.
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Affiliation(s)
- J Wensorra
- Institute for Bio and Nanosystems (IBN-1) and JARA (Jülich Aachen Research Alliance), Research Centre Jülich GmbH, D-52425 Jülich, Germany
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