1
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Masteghin MG, Gervais T, Clowes SK, Cox DC, Zelyk V, Pattammattel A, Chu YS, Kolev N, Stock TJZ, Curson NJ, Evans PG, Stuckelberger M, Murdin BN. Benchmarking of X-Ray Fluorescence Microscopy with Ion Beam Implanted Samples Showing Detection Sensitivity of Hundreds of Atoms. Small Methods 2024:e2301610. [PMID: 38693080 DOI: 10.1002/smtd.202301610] [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] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 03/25/2024] [Indexed: 05/03/2024]
Abstract
Single impurities in insulators are now often used for quantum sensors and single photon sources, while nanoscale semiconductor doping features are being constructed for electrical contacts in quantum technology devices, implying that new methods for sensitive, non-destructive imaging of single- or few-atom structures are needed. X-ray fluorescence (XRF) can provide nanoscale imaging with chemical specificity, and features comprising as few as 100 000 atoms have been detected without any need for specialized or destructive sample preparation. Presently, the ultimate limits of sensitivity of XRF are unknown - here, gallium dopants in silicon are investigated using a high brilliance, synchrotron source collimated to a small spot. It is demonstrated that with a single-pixel integration time of 1 s, the sensitivity is sufficient to identify a single isolated feature of only 3000 Ga impurities (a mass of just 350 zg). With increased integration (25 s), 650 impurities can be detected. The results are quantified using a calibration sample consisting of precisely controlled numbers of implanted atoms in nanometer-sized structures. The results show that such features can now be mapped quantitatively when calibration samples are used, and suggest that, in the near future, planned upgrades to XRF facilities might achieve single-atom sensitivity.
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Affiliation(s)
- Mateus G Masteghin
- Advanced Technology Institute, University of Surrey, Guildford, GU2 7XH, UK
| | - Toussaint Gervais
- Advanced Technology Institute, University of Surrey, Guildford, GU2 7XH, UK
| | - Steven K Clowes
- Advanced Technology Institute, University of Surrey, Guildford, GU2 7XH, UK
| | - David C Cox
- Advanced Technology Institute, University of Surrey, Guildford, GU2 7XH, UK
| | - Veronika Zelyk
- Advanced Technology Institute, University of Surrey, Guildford, GU2 7XH, UK
| | - Ajith Pattammattel
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Yong S Chu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Nikola Kolev
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Taylor J Z Stock
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Neil J Curson
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Paul G Evans
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Michael Stuckelberger
- Center for X-Ray and Nano Science CXNS, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607, Hamburg, Germany
| | - Benedict N Murdin
- Advanced Technology Institute, University of Surrey, Guildford, GU2 7XH, UK
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2
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Stock TJZ, Warschkow O, Constantinou PC, Bowler DR, Schofield SR, Curson NJ. Single-Atom Control of Arsenic Incorporation in Silicon for High-Yield Artificial Lattice Fabrication. Adv Mater 2024:e2312282. [PMID: 38380859 DOI: 10.1002/adma.202312282] [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] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/29/2024] [Indexed: 02/22/2024]
Abstract
Artificial lattices constructed from individual dopant atoms within a semiconductor crystal hold promise to provide novel materials with tailored electronic, magnetic, and optical properties. These custom-engineered lattices are anticipated to enable new, fundamental discoveries in condensed matter physics and lead to the creation of new semiconductor technologies including analog quantum simulators and universal solid-state quantum computers. This work reports precise and repeatable, substitutional incorporation of single arsenic atoms into a silicon lattice. A combination of scanning tunneling microscopy hydrogen resist lithography and a detailed statistical exploration of the chemistry of arsine on the hydrogen-terminated silicon (001) surface are employed to show that single arsenic dopants can be deterministically placed within four silicon lattice sites and incorporated with 97 ± 2% yield. These findings bring closer to the ultimate frontier in semiconductor technology: the deterministic assembly of atomically precise dopant and qubit arrays at arbitrarily large scales.
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Affiliation(s)
- Taylor J Z Stock
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK
- Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE, UK
| | - Oliver Warschkow
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK
| | - Procopios C Constantinou
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK
| | - David R Bowler
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK
- Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | - Steven R Schofield
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK
- Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | - Neil J Curson
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK
- Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE, UK
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3
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Constantinou P, Stock TJZ, Tseng LT, Kazazis D, Muntwiler M, Vaz CAF, Ekinci Y, Aeppli G, Curson NJ, Schofield SR. EUV-induced hydrogen desorption as a step towards large-scale silicon quantum device patterning. Nat Commun 2024; 15:694. [PMID: 38267459 PMCID: PMC10808421 DOI: 10.1038/s41467-024-44790-6] [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: 07/26/2023] [Accepted: 01/02/2024] [Indexed: 01/26/2024] Open
Abstract
Atomically precise hydrogen desorption lithography using scanning tunnelling microscopy (STM) has enabled the development of single-atom, quantum-electronic devices on a laboratory scale. Scaling up this technology to mass-produce these devices requires bridging the gap between the precision of STM and the processes used in next-generation semiconductor manufacturing. Here, we demonstrate the ability to remove hydrogen from a monohydride Si(001):H surface using extreme ultraviolet (EUV) light. We quantify the desorption characteristics using various techniques, including STM, X-ray photoelectron spectroscopy (XPS), and photoemission electron microscopy (XPEEM). Our results show that desorption is induced by secondary electrons from valence band excitations, consistent with an exactly solvable non-linear differential equation and compatible with the current 13.5 nm (~92 eV) EUV standard for photolithography; the data imply useful exposure times of order minutes for the 300 W sources characteristic of EUV infrastructure. This is an important step towards the EUV patterning of silicon surfaces without traditional resists, by offering the possibility for parallel processing in the fabrication of classical and quantum devices through deterministic doping.
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Affiliation(s)
- Procopios Constantinou
- London Centre for Nanotechnology, University College London, WC1H 0AH, London, UK.
- Department of Physics and Astronomy, University College London, WC1E 6BT, London, UK.
- Paul Scherrer Institute, 5232, Villigen PSI, Switzerland.
| | - Taylor J Z Stock
- London Centre for Nanotechnology, University College London, WC1H 0AH, London, UK
- Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE, UK
| | - Li-Ting Tseng
- Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | | | | | - Carlos A F Vaz
- Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | - Yasin Ekinci
- Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | - Gabriel Aeppli
- Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
- Department of Physics, ETH Zürich, 8093, Zürich, Switzerland
- Quantum Center, Eidgenössische Technische Hochschule Zurich (ETHZ), 8093, Zurich, Switzerland
| | - Neil J Curson
- London Centre for Nanotechnology, University College London, WC1H 0AH, London, UK
- Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE, UK
| | - Steven R Schofield
- London Centre for Nanotechnology, University College London, WC1H 0AH, London, UK.
- Department of Physics and Astronomy, University College London, WC1E 6BT, London, UK.
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4
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Constantinou P, Stock TJZ, Crane E, Kölker A, van Loon M, Li J, Fearn S, Bornemann H, D'Anna N, Fisher AJ, Strocov VN, Aeppli G, Curson NJ, Schofield SR. Momentum-Space Imaging of Ultra-Thin Electron Liquids in δ-Doped Silicon. Adv Sci (Weinh) 2023; 10:e2302101. [PMID: 37469010 PMCID: PMC10520640 DOI: 10.1002/advs.202302101] [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] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 06/24/2023] [Indexed: 07/21/2023]
Abstract
Two-dimensional dopant layers (δ-layers) in semiconductors provide the high-mobility electron liquids (2DELs) needed for nanoscale quantum-electronic devices. Key parameters such as carrier densities, effective masses, and confinement thicknesses for 2DELs have traditionally been extracted from quantum magnetotransport. In principle, the parameters are immediately readable from the one-electron spectral function that can be measured by angle-resolved photoemission spectroscopy (ARPES). Here, buried 2DEL δ-layers in silicon are measured with soft X-ray (SX) ARPES to obtain detailed information about their filled conduction bands and extract device-relevant properties. This study takes advantage of the larger probing depth and photon energy range of SX-ARPES relative to vacuum ultraviolet (VUV) ARPES to accurately measure the δ-layer electronic confinement. The measurements are made on ambient-exposed samples and yield extremely thin (< 1 nm) and dense (≈1014 cm-2 ) 2DELs. Critically, this method is used to show that δ-layers of arsenic exhibit better electronic confinement than δ-layers of phosphorus fabricated under identical conditions.
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Affiliation(s)
- Procopios Constantinou
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
- Photon Science DivisionPaul Scherrer InstitutVilligen‐PSI5232Switzerland
| | - Taylor J. Z. Stock
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Eleanor Crane
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Alexander Kölker
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Marcel van Loon
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
| | - Juerong Li
- Advanced Technology InstituteUniversity of SurreyGuildfordGU2 7XHUK
| | - Sarah Fearn
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of MaterialsImperial College of LondonLondonSW7 2AZUK
| | - Henric Bornemann
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
| | - Nicolò D'Anna
- Photon Science DivisionPaul Scherrer InstitutVilligen‐PSI5232Switzerland
| | - Andrew J. Fisher
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
| | | | - Gabriel Aeppli
- Photon Science DivisionPaul Scherrer InstitutVilligen‐PSI5232Switzerland
- Institute of PhysicsEcole Polytechnique Fédérale de Lausanne (EPFL)Lausanne1015Switzerland
- Department of PhysicsETH ZürichZurich8093Switzerland
- Quantum CenterEidgenössische Technische Hochschule Zurich (ETHZ)Zurich8093Switzerland
| | - Neil J. Curson
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Steven R. Schofield
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
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5
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Lundgren EA, Byron C, Constantinou P, Stock TJZ, Curson NJ, Thomsen L, Warschkow O, Teplyakov AV, Schofield SR. Adsorption and Thermal Decomposition of Triphenyl Bismuth on Silicon (001). J Phys Chem C Nanomater Interfaces 2023; 127:16433-16441. [PMID: 37646007 PMCID: PMC10461293 DOI: 10.1021/acs.jpcc.3c03916] [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] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 07/28/2023] [Indexed: 09/01/2023]
Abstract
We investigate the adsorption and thermal decomposition of triphenyl bismuth (TPB) on the silicon (001) surface using atomic-resolution scanning tunneling microscopy, synchrotron-based X-ray photoelectron spectroscopy, and density functional theory calculations. Our results show that the adsorption of TPB at room temperature creates both bismuth-silicon and phenyl-silicon bonds. Annealing above room temperature leads to increased chemical interactions between the phenyl groups and the silicon surface, followed by phenyl detachment and bismuth subsurface migration. The thermal decomposition of the carbon fragments leads to the formation of silicon carbide at the surface. This chemical understanding of the process allows for controlled bismuth introduction into the near surface of silicon and opens pathways for ultra-shallow doping approaches.
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Affiliation(s)
- Eric A.
S. Lundgren
- London
Centre for Nanotechnology, University College
London, WC1H 0AH London, U.K.
- Department
of Physics and Astronomy, University College
London, WC1E 6BT London, U.K.
| | - Carly Byron
- Department
of Chemistry and Biochemistry, University
of Delaware, Newark, Delaware 19716, United States
| | - Procopios Constantinou
- London
Centre for Nanotechnology, University College
London, WC1H 0AH London, U.K.
- Department
of Physics and Astronomy, University College
London, WC1E 6BT London, U.K.
- Paul
Scherrer Institute, 5232 Villigen, Switzerland
| | - Taylor J. Z. Stock
- London
Centre for Nanotechnology, University College
London, WC1H 0AH London, U.K.
- Department
of Electronic and Electrical Engineering, University College London, WC1E 7JE London, U.K.
| | - Neil J. Curson
- London
Centre for Nanotechnology, University College
London, WC1H 0AH London, U.K.
- Department
of Electronic and Electrical Engineering, University College London, WC1E 7JE London, U.K.
| | - Lars Thomsen
- Australian
Synchrotron, ANSTO, Clayton, Victoria 3168, Australia
| | - Oliver Warschkow
- London
Centre for Nanotechnology, University College
London, WC1H 0AH London, U.K.
| | - Andrew V. Teplyakov
- Department
of Chemistry and Biochemistry, University
of Delaware, Newark, Delaware 19716, United States
| | - Steven R. Schofield
- London
Centre for Nanotechnology, University College
London, WC1H 0AH London, U.K.
- Department
of Physics and Astronomy, University College
London, WC1E 6BT London, U.K.
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6
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Tseng LT, Karadan P, Kazazis D, Constantinou PC, Stock TJ, Curson NJ, Schofield SR, Muntwiler M, Aeppli G, Ekinci Y. Resistless EUV lithography: Photon-induced oxide patterning on silicon. Sci Adv 2023; 9:eadf5997. [PMID: 37075116 PMCID: PMC10115406 DOI: 10.1126/sciadv.adf5997] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In this work, we show the feasibility of extreme ultraviolet (EUV) patterning on an HF-treated silicon (100) surface in the absence of a photoresist. EUV lithography is the leading lithography technique in semiconductor manufacturing due to its high resolution and throughput, but future progress in resolution can be hampered because of the inherent limitations of the resists. We show that EUV photons can induce surface reactions on a partially hydrogen-terminated silicon surface and assist the growth of an oxide layer, which serves as an etch mask. This mechanism is different from the hydrogen desorption in scanning tunneling microscopy-based lithography. We achieve silicon dioxide/silicon gratings with 75-nanometer half-pitch and 31-nanometer height, demonstrating the efficacy of the method and the feasibility of patterning with EUV lithography without the use of a photoresist. Further development of the resistless EUV lithography method can be a viable approach to nanometer-scale lithography by overcoming the inherent resolution and roughness limitations of photoresist materials.
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Affiliation(s)
- Li-Ting Tseng
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | | | - Dimitrios Kazazis
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Corresponding author.
| | | | - Taylor J. Z. Stock
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK
| | - Neil J. Curson
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK
| | - Steven R. Schofield
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | | | - Gabriel Aeppli
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Laboratory for Solid State Physics and Quantum Center, ETH-Zürich, 8093 Zürich, Switzerland
- Institut de Physique, EPFL, 1015 Lausanne, Switzerland
| | - Yasin Ekinci
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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7
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Hofmann EVS, Stock TJZ, Warschkow O, Conybeare R, Curson NJ, Schofield SR. Room Temperature Incorporation of Arsenic Atoms into the Germanium (001) Surface. Angew Chem Int Ed Engl 2023; 62:e202213982. [PMID: 36484458 PMCID: PMC10108107 DOI: 10.1002/anie.202213982] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/29/2022] [Accepted: 12/09/2022] [Indexed: 12/13/2022]
Abstract
Germanium has emerged as an exceptionally promising material for spintronics and quantum information applications, with significant fundamental advantages over silicon. However, efforts to create atomic-scale devices using donor atoms as qubits have largely focused on phosphorus in silicon. Positioning phosphorus in silicon with atomic-scale precision requires a thermal incorporation anneal, but the low success rate for this step has been shown to be a fundamental limitation prohibiting the scale-up to large-scale devices. Here, we present a comprehensive study of arsine (AsH3 ) on the germanium (001) surface. We show that, unlike any previously studied dopant precursor on silicon or germanium, arsenic atoms fully incorporate into substitutional surface lattice sites at room temperature. Our results pave the way for the next generation of atomic-scale donor devices combining the superior electronic properties of germanium with the enhanced properties of arsine/germanium chemistry that promises scale-up to large numbers of deterministically placed qubits.
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Affiliation(s)
- Emily V S Hofmann
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Electronic and Electrical Engineering, University College London, London, WC1E 6BT, UK.,IHP Leibniz-Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236, Frankfurt (Oder), Germany
| | - Taylor J Z Stock
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Electronic and Electrical Engineering, University College London, London, WC1E 6BT, UK
| | - Oliver Warschkow
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Rebecca Conybeare
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | - Neil J Curson
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Electronic and Electrical Engineering, University College London, London, WC1E 6BT, UK
| | - Steven R Schofield
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
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8
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Hofmann EVS, Stock TJZ, Warschkow O, Conybeare R, Curson NJ, Scholfield S. Room Temperature Incorporation of Arsenic Atoms into the Germanium (001) Surface. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202213982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - Taylor J. Z. Stock
- University College London London Centre for Nanotechnology UNITED KINGDOM
| | - Oliver Warschkow
- University College London London Centre for Nanotechnology UNITED KINGDOM
| | - Rebecca Conybeare
- University College London London Centre for Nanotechnology UNITED KINGDOM
| | - Neil J. Curson
- University College London London Centre for Nanotechnology UNITED KINGDOM
| | - Steven Scholfield
- University College London London Centre for Nanotechnology 17-19 Gordon St WC1H 0AH London UNITED KINGDOM
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9
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Kölker A, Gramse G, Stock TJZ, Aeppli G, Curson NJ. In operando charge transport imaging of atomically thin dopant nanostructures in silicon. Nanoscale 2022; 14:6437-6448. [PMID: 35416206 DOI: 10.1039/d1nr08381c] [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: 06/14/2023]
Abstract
Novel approaches to materials design, fabrication processes and device architectures have accelerated next-generation electronics component production, pushing device dimensions down to the nano- and atomic-scale. For device metrology methods to keep up with these developments, they should not only measure the relevant electrical parameters at these length-scales, but ideally do so during active operation of the device. Here, we demonstrate such a capability using the full functionality of an advanced scanning microwave/scanning capacitance/kelvin probe atomic force microscope to inspect the charge transport and performance of an atomically thin buried phosphorus wire device during electrical operation. By interrogation of the contact potential, carrier density and transport properties, we demonstrate the capability to distinguish between the different material components and device imperfections, and assess their contributions to the overall electric characteristics of the device in operando. Our experimental methodology will facilitate rapid feedback for the fabrication of patterned nanoscale dopant device components in silicon, now important for the emerging field of silicon quantum information technology. More generally, the versatile setup, with its advanced inspection capabilities, delivers a comprehensive method to determine the performance of nanoscale devices while they function, in a broad range of material systems.
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Affiliation(s)
- Alexander Kölker
- London Centre of Nanotechnology, UCL, 17-19 Gordon Street, London WC1H 0AH, UK.
| | - Georg Gramse
- Johannes Kepler University, Biophysics Institute, Gruberstrasse 40, 4020 Linz, Austria
- Keysight Laboratories, Keysight Technologies, Inc., Gruberstrasse 40, 4020 Linz, Austria
| | - Taylor J Z Stock
- London Centre of Nanotechnology, UCL, 17-19 Gordon Street, London WC1H 0AH, UK.
| | - Gabriel Aeppli
- Department of Physics and Quantum Center, ETH, Zurich CH-8093, Switzerland
- Institut de Physique, EPFL, Lausanne CH-1015, Switzerland
- Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - Neil J Curson
- London Centre of Nanotechnology, UCL, 17-19 Gordon Street, London WC1H 0AH, UK.
- Department of Electronic and Electrical Engineering, UCL, Torrington Place, London, WC1E 7JE, UK
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10
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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: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Gramse G, Kölker A, Lim T, Stock TJZ, Solanki H, Schofield SR, Brinciotti E, Aeppli G, Kienberger F, Curson NJ. Nondestructive imaging of atomically thin nanostructures buried in silicon. Sci Adv 2017; 3:e1602586. [PMID: 28782006 PMCID: PMC5489266 DOI: 10.1126/sciadv.1602586] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 05/01/2017] [Indexed: 05/05/2023]
Abstract
It is now possible to create atomically thin regions of dopant atoms in silicon patterned with lateral dimensions ranging from the atomic scale (angstroms) to micrometers. These structures are building blocks of quantum devices for physics research and they are likely also to serve as key components of devices for next-generation classical and quantum information processing. Until now, the characteristics of buried dopant nanostructures could only be inferred from destructive techniques and/or the performance of the final electronic device; this severely limits engineering and manufacture of real-world devices based on atomic-scale lithography. Here, we use scanning microwave microscopy (SMM) to image and electronically characterize three-dimensional phosphorus nanostructures fabricated via scanning tunneling microscope-based lithography. The SMM measurements, which are completely nondestructive and sensitive to as few as 1900 to 4200 densely packed P atoms 4 to 15 nm below a silicon surface, yield electrical and geometric properties in agreement with those obtained from electrical transport and secondary ion mass spectroscopy for unpatterned phosphorus δ layers containing ~1013 P atoms. The imaging resolution was 37 ± 1 nm in lateral and 4 ± 1 nm in vertical directions, both values depending on SMM tip size and depth of dopant layers. In addition, finite element modeling indicates that resolution can be substantially improved using further optimized tips and microwave gradient detection. Our results on three-dimensional dopant structures reveal reduced carrier mobility for shallow dopant layers and suggest that SMM could aid the development of fabrication processes for surface code quantum computers.
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Affiliation(s)
- Georg Gramse
- Johannes Kepler University, Biophysics Institute, Gruberstrasse 40, 4020 Linz, Austria
- Corresponding author. (G.G.); (N.J.C.)
| | - Alexander Kölker
- London Centre of Nanotechnology, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH, UK
- Department of Electronic and Electrical Engineering, UCL, Torrington Place, London WC1E 7JE, UK
| | - Tingbin Lim
- London Centre of Nanotechnology, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH, UK
| | - Taylor J. Z. Stock
- London Centre of Nanotechnology, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH, UK
| | - Hari Solanki
- London Centre of Nanotechnology, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH, UK
| | - Steven R. Schofield
- London Centre of Nanotechnology, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH, UK
- Department of Physics and Astronomy, UCL, Gower Street, London WC1E 6BT, UK
| | - Enrico Brinciotti
- Keysight Laboratories, Keysight Technologies Inc., Gruberstrasse 40, 4020 Linz, Austria
| | - Gabriel Aeppli
- Department of Physics, ETH, Zurich CH-8093, Switzerland
- Institut de Physique, École polytechnique fédérale de Lausanne, Lausanne CH-1015, Switzerland
- Paul Scherrer Institut, Villigen CH-5232, Switzerland
- Bio Nano Consulting, Gridiron Building, One Pancras Square, London N1C 4AG, UK
| | - Ferry Kienberger
- Keysight Laboratories, Keysight Technologies Inc., Gruberstrasse 40, 4020 Linz, Austria
| | - Neil J. Curson
- London Centre of Nanotechnology, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH, UK
- Department of Electronic and Electrical Engineering, UCL, Torrington Place, London WC1E 7JE, UK
- Corresponding author. (G.G.); (N.J.C.)
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12
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Thompson RJ, Bennett T, Fearn S, Kamaludin M, Kloc C, McPhail DS, Mitrofanov O, Curson NJ. Channels of oxygen diffusion in single crystal rubrene revealed. Phys Chem Chem Phys 2016; 18:32302-32307. [DOI: 10.1039/c6cp05369f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Oxygen diffusion channels are imaged in the single crystal organic semiconductor rubrene using Time of Flight Secondary Ion Mass Spectroscopy.
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Affiliation(s)
- Robert J. Thompson
- London Centre for Nanotechnology
- London
- UK
- Department Electronic & Electrical Engineering
- UCL
| | - Thomas Bennett
- Department Materials
- Imperial College London
- Royal School of Mines
- London
- UK
| | - Sarah Fearn
- Department Materials
- Imperial College London
- Royal School of Mines
- London
- UK
| | | | - Christian Kloc
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore
| | - David S. McPhail
- Department of Chemistry and Biochemistry
- University of Texas at Dallas
- USA
| | | | - Neil J. Curson
- London Centre for Nanotechnology
- London
- UK
- Department Electronic & Electrical Engineering
- UCL
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13
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Grzela T, Capellini G, Koczorowski W, Schubert MA, Czajka R, Curson NJ, Heidmann I, Schmidt T, Falta J, Schroeder T. Growth and evolution of nickel germanide nanostructures on Ge(001). Nanotechnology 2015; 26:385701. [PMID: 26335383 DOI: 10.1088/0957-4484/26/38/385701] [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: 06/05/2023]
Abstract
Nickel germanide is deemed an excellent material system for low resistance contact formation for future Ge device modules integrated into mainstream, Si-based integrated circuit technologies. In this study, we present a multi-technique experimental study on the formation processes of nickel germanides on Ge(001). We demonstrate that room temperature deposition of ∼1 nm of Ni on Ge(001) is realized in the Volmer-Weber growth mode. Subsequent thermal annealing results first in the formation of a continuous NixGey wetting layer featuring well-defined terrace morphology. Upon increasing the annealing temperature to 300 °C, we observed the onset of a de-wetting process, characterized by the appearance of voids on the NixGey terraces. Annealing above 300 °C enhances this de-wetting process and the surface evolves gradually towards the formation of well-ordered, rectangular NixGey 3D nanostructures. Annealing up to 500 °C induces an Ostwald ripening phenomenon, with smaller nanoislands disappearing and larger ones increasing their size. Subsequent annealing to higher temperatures drives the Ni-germanide diffusion into the bulk and the consequent formation of highly ordered, {111} faceted Ni-Ge nanocrystals featuring an epitaxial relationship with the substrate Ni-Ge (101); (010) || Ge(001); (110).
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Affiliation(s)
- T Grzela
- IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
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14
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Koczorowski W, Grzela T, Radny MW, Schofield SR, Capellini G, Czajka R, Schroeder T, Curson NJ. Ba termination of Ge(001) studied with STM. Nanotechnology 2015; 26:155701. [PMID: 25797886 DOI: 10.1088/0957-4484/26/15/155701] [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: 06/04/2023]
Abstract
We use controlled annealing to tune the interfacial properties of a sub-monolayer and monolayer coverages of Ba atoms deposited on Ge(001), enabling the generation of either of two fundamentally distinct interfacial phases, as revealed by scanning tunneling microscopy. Firstly we identify the two key structural phases associated with this adsorption system, namely on-top adsorption and surface alloy formation, by performing a deposition and annealing experiment at a coverage low enough (∼0.15 ML) that isolated Ba-related features can be individually resolved. Subsequently we investigate the monolayer coverage case, of interest for passivation schemes of future Ge based devices, for which we find that the thermal evaporation of Ba onto a Ge(001) surface at room temperature results in on-top adsorption. This separation (lack of intermixing) between Ba and Ge layers is retained through successive annealing steps to temperatures of 470, 570, 670 and 770 K although a gradual ordering of the Ba layer is observed at 570 K and above, accompanied by a decrease in Ba layer density. Annealing above 770 K produces the 2D surface alloy phase accompanied by strain relief through monolayer height trench formation. An annealing temperature of 1070 K sees a further change in surface morphology but retention of the 2D surface alloy characteristic. These results are discussed in view of their possible implications for future semiconductor integrated circuit technology.
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Affiliation(s)
- W Koczorowski
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, UK. Institute of Physics, Poznan University of Technology, ul. Piotrowo 3, 60-965 Poznan, Poland
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15
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Sinthiptharakoon K, Schofield SR, Studer P, Brázdová V, Hirjibehedin CF, Bowler DR, Curson NJ. Investigating individual arsenic dopant atoms in silicon using low-temperature scanning tunnelling microscopy. J Phys Condens Matter 2014; 26:012001. [PMID: 24304933 DOI: 10.1088/0953-8984/26/1/012001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We study subsurface arsenic dopants in a hydrogen-terminated Si(001) sample at 77 K, using scanning tunnelling microscopy and spectroscopy. We observe a number of different dopant-related features that fall into two classes, which we call As1 and As2. When imaged in occupied states, the As1 features appear as anisotropic protrusions superimposed on the silicon surface topography and have maximum intensities lying along particular crystallographic orientations. In empty-state images the features all exhibit long-range circular protrusions. The images are consistent with buried dopants that are in the electrically neutral (D0) charge state when imaged in filled states, but become positively charged (D+) through electrostatic ionization when imaged under empty-state conditions, similar to previous observations of acceptors in GaAs. Density functional theory calculations predict that As dopants in the third layer of the sample induce two states lying just below the conduction-band edge, which hybridize with the surface structure creating features with the surface symmetry consistent with our STM images. The As2 features have the surprising characteristic of appearing as a protrusion in filled-state images and an isotropic depression in empty-state images, suggesting they are negatively charged at all biases. We discuss the possible origins of this feature.
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16
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Schofield SR, Studer P, Hirjibehedin CF, Curson NJ, Aeppli G, Bowler DR. Quantum engineering at the silicon surface using dangling bonds. Nat Commun 2013; 4:1649. [PMID: 23552064 PMCID: PMC3644071 DOI: 10.1038/ncomms2679] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [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: 07/05/2012] [Accepted: 02/28/2013] [Indexed: 11/25/2022] Open
Abstract
Individual atoms and ions are now routinely manipulated using scanning tunnelling microscopes or electromagnetic traps for the creation and control of artificial quantum states. For applications such as quantum information processing, the ability to introduce multiple atomic-scale defects deterministically in a semiconductor is highly desirable. Here we use a scanning tunnelling microscope to fabricate interacting chains of dangling bond defects on the hydrogen-passivated silicon (001) surface. We image both the ground-state and the excited-state probability distributions of the resulting artificial molecular orbitals, using the scanning tunnelling microscope tip bias and tip-sample separation as gates to control which states contribute to the image. Our results demonstrate that atomically precise quantum states can be fabricated on silicon, and suggest a general model of quantum-state fabrication using other chemically passivated semiconductor surfaces where single-atom depassivation can be achieved using scanning tunnelling microscopy. The ability to add and move individual atoms on a surface with a scanning tunnelling microscope enables precise control over the electronic quantum states of the surface. Schofield et al. show that removing hydrogen atoms from a passivated silicon surface can be used to generate and control such states.
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Affiliation(s)
- S R Schofield
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK.
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17
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Thompson RJ, Fearn S, Tan KJ, Cramer HG, Kloc CL, Curson NJ, Mitrofanov O. Revealing surface oxidation on the organic semi-conducting single crystal rubrene with time of flight secondary ion mass spectroscopy. Phys Chem Chem Phys 2013; 15:5202-7. [DOI: 10.1039/c3cp50310k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [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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18
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Abstract
The optical, electrical, and chemical properties of semiconductor surfaces are largely determined by their electronic states close to the Fermi level (E{F}). We use scanning tunneling microscopy and density functional theory to clarify the fundamental nature of the ground state Ge(001) electronic structure near E{F}, and resolve previously contradictory photoemission and tunneling spectroscopy data. The highest energy occupied surface states were found to be exclusively back bond states, in contrast to the Si(001) surface, where dangling bond states also lie at the top of the valence band.
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Affiliation(s)
- M W Radny
- School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan 2308, Australia.
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19
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Schofield SR, Curson NJ, Warschkow O, Marks NA, Wilson HF, Simmons MY, Smith PV, Radny MW, McKenzie DR, Clark RG. Phosphine dissociation and diffusion on Si(001) observed at the atomic scale. J Phys Chem B 2006; 110:3173-9. [PMID: 16494325 DOI: 10.1021/jp054646v] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A detailed atomic-resolution scanning tunneling microscopy (STM) and density functional theory study of the adsorption, dissociation, and surface diffusion of phosphine (PH(3)) on Si(001) is presented. Adsorbate coverages from approximately 0.01 monolayer to saturation are investigated, and adsorption is performed at room temperature and 120 K. It is shown that PH(3) dissociates upon adsorption to Si(001) at room temperature to produce both PH(2) + H and PH + 2H. These appear in atomic-resolution STM images as features asymmetric-about and centered-upon the dimer rows, respectively. The ratio of PH(2) to PH is a function of both dose rate and temperature, and the dissociation of PH(2) to PH occurs on a time scale of minutes at room temperature. Time-resolved in situ STM observations of these adsorbates show the surface diffusion of PH(2) adsorbates (mediated by its lone pair electrons) and the dissociation of PH(2) to PH. The surface diffusion of PH(2) results in the formation of hemihydride dimers on low-dosed Si(001) surfaces and the ordering of PH molecules along dimer rows at saturation coverages. The observations presented here have important implications for the fabrication of atomic-scale P dopant structures in Si, and the methodology is applicable to other emerging areas of nanotechnology, such as molecular electronics, where unambiguous molecular identification using STM is necessary.
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Affiliation(s)
- Steven R Schofield
- Centre for Quantum Computer Technology, School of Physics, University of New South Wales, Sydney 2052, Australia.
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20
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Wilson HF, Warschkow O, Marks NA, Schofield SR, Curson NJ, Smith PV, Radny MW, McKenzie DR, Simmons MY. Phosphine dissociation on the Si(001) surface. Phys Rev Lett 2004; 93:226102. [PMID: 15601102 DOI: 10.1103/physrevlett.93.226102] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Indexed: 05/24/2023]
Abstract
Density functional calculations are performed to identify features observed in STM experiments after phosphine (PH3) dosing of the Si(001) surface. On the basis of a comprehensive survey of possible structures, energetics, and simulated STM images, three prominent STM features are assigned to structures containing surface bound PH2, PH, and P, respectively. Collectively, the assigned features outline for the first time a detailed mechanism of PH3 dissociation and P incorporation on Si(001).
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Affiliation(s)
- H F Wilson
- Centre for Quantum Computer Technology, School of Physics, The University of Sydney, Sydney 2006, NSW Australia
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21
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Schofield SR, Curson NJ, Simmons MY, Ruess FJ, Hallam T, Oberbeck L, Clark RG. Atomically precise placement of single dopants in si. Phys Rev Lett 2003; 91:136104. [PMID: 14525322 DOI: 10.1103/physrevlett.91.136104] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2003] [Indexed: 05/24/2023]
Abstract
We demonstrate the controlled incorporation of P dopant atoms in Si(001), presenting a new path toward the creation of atomic-scale electronic devices. We present a detailed study of the interaction of PH3 with Si(001) and show that it is possible to thermally incorporate P atoms into Si(001) below the H-desorption temperature. Control over the precise spatial location at which P atoms are incorporated was achieved using STM H lithography. We demonstrate the positioning of single P atoms in Si with approximately 1 nm accuracy and the creation of nanometer wide lines of incorporated P atoms.
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Affiliation(s)
- S R Schofield
- Centre for Quantum Computer Technology, School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
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22
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Clark RG, Brenner R, Buehler TM, Chan V, Curson NJ, Dzurak AS, Gauja E, Goan HS, Greentree AD, Hallam T, Hamilton AR, Hollenberg LCL, Jamieson DN, McCallum JC, Milburn GJ, O'Brien JL, Oberbeck L, Pakes CI, Prawer SD, Reilly DJ, Ruess FJ, Schofield SR, Simmons MY, Stanley FE, Starrett RP, Wellard C, Yang C. Progress in silicon-based quantum computing. Philos Trans A Math Phys Eng Sci 2003; 361:1451-1471. [PMID: 12869321 DOI: 10.1098/rsta.2003.1221] [Citation(s) in RCA: 6] [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: 05/24/2023]
Abstract
We review progress at the Australian Centre for Quantum Computer Technology towards the fabrication and demonstration of spin qubits and charge qubits based on phosphorus donor atoms embedded in intrinsic silicon. Fabrication is being pursued via two complementary pathways: a 'top-down' approach for near-term production of few-qubit demonstration devices and a 'bottom-up' approach for large-scale qubit arrays with sub-nanometre precision. The 'top-down' approach employs a low-energy (keV) ion beam to implant the phosphorus atoms. Single-atom control during implantation is achieved by monitoring on-chip detector electrodes, integrated within the device structure. In contrast, the 'bottom-up' approach uses scanning tunnelling microscope lithography and epitaxial silicon overgrowth to construct devices at an atomic scale. In both cases, surface electrodes control the qubit using voltage pulses, and dual single-electron transistors operating near the quantum limit provide fast read-out with spurious-signal rejection.
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Affiliation(s)
- R G Clark
- Centre for Quantum Computer Technology, School of Physics, University of New South Wales, Sydney 2052, Australia
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