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Stock TJZ, Warschkow O, Constantinou PC, Li J, Fearn S, Crane E, Hofmann EVS, Kölker A, McKenzie DR, Schofield SR, Curson NJ. Atomic-Scale Patterning of Arsenic in Silicon by Scanning Tunneling Microscopy. ACS NANO 2020; 14:3316-3327. [PMID: 32142256 PMCID: PMC7146850 DOI: 10.1021/acsnano.9b08943] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Over the past two decades, prototype devices for future classical and quantum computing technologies have been fabricated by using scanning tunneling microscopy and hydrogen resist lithography to position phosphorus atoms in silicon with atomic-scale precision. Despite these successes, phosphine remains the only donor precursor molecule to have been demonstrated as compatible with the hydrogen resist lithography technique. The potential benefits of atomic-scale placement of alternative dopant species have, until now, remained unexplored. In this work, we demonstrate the successful fabrication of atomic-scale structures of arsenic-in-silicon. Using a scanning tunneling microscope tip, we pattern a monolayer hydrogen mask to selectively place arsenic atoms on the Si(001) surface using arsine as the precursor molecule. We fully elucidate the surface chemistry and reaction pathways of arsine on Si(001), revealing significant differences to phosphine. We explain how these differences result in enhanced surface immobilization and in-plane confinement of arsenic compared to phosphorus, and a dose-rate independent arsenic saturation density of 0.24 ± 0.04 monolayers. We demonstrate the successful encapsulation of arsenic delta-layers using silicon molecular beam epitaxy, and find electrical characteristics that are competitive with equivalent structures fabricated with phosphorus. Arsenic delta-layers are also found to offer confinement as good as similarly prepared phosphorus layers, while still retaining >80% carrier activation and sheet resistances of <2 kΩ/square. These excellent characteristics of arsenic represent opportunities to enhance existing capabilities of atomic-scale fabrication of dopant structures in silicon, and may be important for three-dimensional devices, where vertical control of the position of device components is critical.
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Affiliation(s)
- Taylor J. Z. Stock
- London
Centre for Nanotechnology, University College
London, London WC1H 0AH, U.K.
| | - Oliver Warschkow
- Centre
for Quantum Computation and Communication Technology, School of Physics, The University of Sydney, Sydney, NSW 2006, Australia
| | | | - Juerong Li
- Advanced
Technology Institute, University of Surrey, Guildford GU2 7XH, U.K.
| | - Sarah Fearn
- London
Centre for Nanotechnology, University College
London, London WC1H 0AH, U.K.
- Department
of Materials, Imperial College of London, London SW7 2AZ, U.K.
| | - Eleanor Crane
- London
Centre for Nanotechnology, University College
London, London WC1H 0AH, U.K.
| | - Emily V. S. Hofmann
- London
Centre for Nanotechnology, University College
London, London WC1H 0AH, U.K.
- IHP
− Leibniz-Institut für Innovative Mikroelektronik, Frankfurt (Oder) 15236, Germany
| | - Alexander Kölker
- London
Centre for Nanotechnology, University College
London, London WC1H 0AH, U.K.
| | - David R. McKenzie
- Centre
for Quantum Computation and Communication Technology, School of Physics, The University of Sydney, Sydney, NSW 2006, Australia
| | - Steven R. Schofield
- London
Centre for Nanotechnology, University College
London, London WC1H 0AH, U.K.
- Department
of Physics and Astronomy, University College
London, London WC1E 6BT, U.K.
| | - Neil J. Curson
- London
Centre for Nanotechnology, University College
London, London WC1H 0AH, U.K.
- Department
of Electronic and Electrical Engineering, University College London, London WC1E 7JE, U.K.
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Schaal S, Ahmed I, Haigh JA, Hutin L, Bertrand B, Barraud S, Vinet M, Lee CM, Stelmashenko N, Robinson JWA, Qiu JY, Hacohen-Gourgy S, Siddiqi I, Gonzalez-Zalba MF, Morton JJL. Fast Gate-Based Readout of Silicon Quantum Dots Using Josephson Parametric Amplification. PHYSICAL REVIEW LETTERS 2020; 124:067701. [PMID: 32109120 DOI: 10.1103/physrevlett.124.067701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 01/17/2020] [Indexed: 06/10/2023]
Abstract
Spins in silicon quantum devices are promising candidates for large-scale quantum computing. Gate-based sensing of spin qubits offers a compact and scalable readout with high fidelity, however, further improvements in sensitivity are required to meet the fidelity thresholds and measurement timescales needed for the implementation of fast feedback in error correction protocols. Here, we combine radio-frequency gate-based sensing at 622 MHz with a Josephson parametric amplifier, that operates in the 500-800 MHz band, to reduce the integration time required to read the state of a silicon double quantum dot formed in a nanowire transistor. Based on our achieved signal-to-noise ratio, we estimate that singlet-triplet single-shot readout with an average fidelity of 99.7% could be performed in 1 μs, well below the requirements for fault-tolerant readout and 30 times faster than without the Josephson parametric amplifier. Additionally, the Josephson parametric amplifier allows operation at a lower radio-frequency power while maintaining identical signal-to-noise ratio. We determine a noise temperature of 200 mK with a contribution from the Josephson parametric amplifier (25%), cryogenic amplifier (25%) and the resonator (50%), showing routes to further increase the readout speed.
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Affiliation(s)
- S Schaal
- London Centre for Nanotechnology, University College London, London WC1H 0AH, United Kingdom
| | - I Ahmed
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - J A Haigh
- Hitachi Cambridge Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - L Hutin
- CEA, LETI, Minatec Campus, F-38054 Grenoble, France
| | - B Bertrand
- CEA, LETI, Minatec Campus, F-38054 Grenoble, France
| | - S Barraud
- CEA, LETI, Minatec Campus, F-38054 Grenoble, France
| | - M Vinet
- CEA, LETI, Minatec Campus, F-38054 Grenoble, France
| | - C-M Lee
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - N Stelmashenko
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - J W A Robinson
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - J Y Qiu
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley California 94720, USA
| | - S Hacohen-Gourgy
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley California 94720, USA
| | - I Siddiqi
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley California 94720, USA
| | - M F Gonzalez-Zalba
- Hitachi Cambridge Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - J J L Morton
- London Centre for Nanotechnology, University College London, London WC1H 0AH, United Kingdom
- Department of Electronic & Electrical Engineering, University College London, London WC1E 7JE, United Kingdom
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Unusual Quantum Transport Mechanisms in Silicon Nano-Devices. ENTROPY 2019; 21:e21070676. [PMID: 33267390 PMCID: PMC7515173 DOI: 10.3390/e21070676] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/25/2019] [Accepted: 07/09/2019] [Indexed: 11/16/2022]
Abstract
Silicon-based materials have been the leading platforms for the development of classical information science and are now one of the major contenders for future developments in the field of quantum information science. In this short review paper, while discussing only some examples, I will describe how silicon Complementary-Metal-Oxide-Semiconductor (CMOS) compatible materials have been able to provide platforms for the observation of some of the most unusual transport phenomena in condensed matter physics.
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Humble TS, Ericson MN, Jakowski J, Huang J, Britton C, Curtis FG, Dumitrescu EF, Mohiyaddin FA, Sumpter BG. A computational workflow for designing silicon donor qubits. NANOTECHNOLOGY 2016; 27:424002. [PMID: 27641513 DOI: 10.1088/0957-4484/27/42/424002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Developing devices that can reliably and accurately demonstrate the principles of superposition and entanglement is an on-going challenge for the quantum computing community. Modeling and simulation offer attractive means of testing early device designs and establishing expectations for operational performance. However, the complex integrated material systems required by quantum device designs are not captured by any single existing computational modeling method. We examine the development and analysis of a multi-staged computational workflow that can be used to design and characterize silicon donor qubit systems with modeling and simulation. Our approach integrates quantum chemistry calculations with electrostatic field solvers to perform detailed simulations of a phosphorus dopant in silicon. We show how atomistic details can be synthesized into an operational model for the logical gates that define quantum computation in this particular technology. The resulting computational workflow realizes a design tool for silicon donor qubits that can help verify and validate current and near-term experimental devices.
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Affiliation(s)
- Travis S Humble
- Quantum Computing Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA. Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA. Bredesen Center for Interdisciplinary Research, University of Tennessee, Knoxville, TN, USA
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