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McGilligan JP, Gallacher K, Griffin PF, Paul DJ, Arnold AS, Riis E. Micro-fabricated components for cold atom sensors. Rev Sci Instrum 2022; 93:091101. [PMID: 36182455 DOI: 10.1063/5.0101628] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 08/02/2022] [Indexed: 06/16/2023]
Abstract
Laser cooled atoms have proven transformative for precision metrology, playing a pivotal role in state-of-the-art clocks and interferometers and having the potential to provide a step-change in our modern technological capabilities. To successfully explore their full potential, laser cooling platforms must be translated from the laboratory environment and into portable, compact quantum sensors for deployment in practical applications. This transition requires the amalgamation of a wide range of components and expertise if an unambiguously chip-scale cold atom sensor is to be realized. We present recent developments in cold-atom sensor miniaturization, focusing on key components that enable laser cooling on the chip-scale. The design, fabrication, and impact of the components on sensor scalability and performance will be discussed with an outlook to the next generation of chip-scale cold atom devices.
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Affiliation(s)
- J P McGilligan
- SUPA and Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - K Gallacher
- James Watt School of Engineering, University of Glasgow, Glasgow G12 8LT, United Kingdom
| | - P F Griffin
- SUPA and Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - D J Paul
- James Watt School of Engineering, University of Glasgow, Glasgow G12 8LT, United Kingdom
| | - A S Arnold
- SUPA and Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - E Riis
- SUPA and Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom
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2
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Prasad A, Middlemiss RP, Noack A, Anastasiou K, Bramsiepe SG, Toland K, Utting PR, Paul DJ, Hammond GD. A 19 day earth tide measurement with a MEMS gravimeter. Sci Rep 2022; 12:13091. [PMID: 35906251 PMCID: PMC9338064 DOI: 10.1038/s41598-022-16881-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [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: 12/14/2021] [Accepted: 07/18/2022] [Indexed: 11/09/2022] Open
Abstract
The measurement of tiny variations in local gravity enables the observation of subterranean features. Gravimeters have historically been extremely expensive instruments, but usable gravity measurements have recently been conducted using MEMS (microelectromechanical systems) sensors. Such sensors are cheap to produce, since they rely on the same fabrication techniques used to produce mobile phone accelerometers. A significant challenge in the development of MEMS gravimeters is maintaining stability over long time periods, which is essential for long term monitoring applications. A standard way to demonstrate gravimeter stability and sensitivity is to measure the periodic elastic distortion of the Earth due to tidal forces-the Earth tides. Here, a 19 day measurement of the Earth tides, with a correlation coefficient to the theoretical signal of 0.975, has been presented. This result demonstrates that this MEMS gravimeter is capable of conducting long-term time-lapse gravimetry, a functionality essential for applications such as volcanology.
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Affiliation(s)
- Abhinav Prasad
- School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK.
| | - Richard P Middlemiss
- School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK.
| | - Andreas Noack
- School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Kristian Anastasiou
- School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Steven G Bramsiepe
- School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Karl Toland
- School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Phoebe R Utting
- School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Douglas J Paul
- James Watt School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK
| | - Giles D Hammond
- School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK.
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3
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Thorburn F, Yi X, Greener ZM, Kirdoda J, Millar RW, Huddleston LL, Paul DJ, Buller GS. Ge-on-Si single-photon avalanche diode detectors for short-wave infrared wavelengths. J Phys Photonics 2022. [DOI: 10.1088/2515-7647/ac3839] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Germanium-on-silicon (Ge-on-Si) based single-photon avalanche diodes (SPADs) have recently emerged as a promising detector candidate for ultra-sensitive and picosecond resolution timing measurement of short-wave infrared (SWIR) photons. Many applications benefit from operating in the SWIR spectral range, such as long distance light detection and ranging, however, there are few single-photon detectors exhibiting the high-performance levels obtained by all-silicon SPADs commonly used for single-photon detection at wavelengths <1 µm. This paper first details the advantages of operating at SWIR wavelengths, the current technologies, and associated issues, and describes the potential of Ge-on-Si SPADs as a single-photon detector technology for this wavelength region. The working principles, fabrication and characterisation processes of such devices are subsequently detailed. We review the research in these single-photon detectors and detail the state-of-the-art performance. Finally, the challenges and future opportunities offered by Ge-on-Si SPAD detectors are discussed.
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4
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Llin LF, Kirdoda J, Thorburn F, Huddleston LL, Greener ZM, Kuzmenko K, Vines P, Dumas DCS, Millar RW, Buller GS, Paul DJ. High sensitivity Ge-on-Si single-photon avalanche diode detectors. Opt Lett 2020; 45:6406-6409. [PMID: 33258823 DOI: 10.1364/ol.396756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
The performance of planar geometry Ge-on-Si single-photon avalanche diode detectors of 26µm diameter is presented. Record low dark count rates are observed, remaining less than 100 K counts per second at 6.6% excess bias and 125 K. Single-photon detection efficiencies are found to be up to 29.4%, and are shown to be temperature insensitive. These performance characteristics lead to a significantly reduced noise equivalent power (NEP) of 7.7×10-17WHz-12 compared to prior planar devices, and represent a two orders of magnitude reduction in NEP compared to previous Ge-on-Si mesa devices of a comparable diameter. Low jitter values of 134±10ps are demonstrated.
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5
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Gallacher K, Millar RW, Paul DJ, Frigerio J, Ballabio A, Isella G, Rusconi F, Biagioni P, Giliberti V, Sorgi A, Baldassarre L, Ortolani M. Characterization of integrated waveguides by atomic-force-microscopy-assisted mid-infrared imaging and spectroscopy. Opt Express 2020; 28:22186-22199. [PMID: 32752485 DOI: 10.1364/oe.393748] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 05/15/2020] [Indexed: 06/11/2023]
Abstract
A novel spectroscopy technique to enable the rapid characterization of discrete mid-infrared integrated photonic waveguides is demonstrated. The technique utilizes lithography patterned polymer blocks that absorb light strongly within the molecular fingerprint region. These act as integrated waveguide detectors when combined with an atomic force microscope that measures the photothermal expansion when infrared light is guided to the block. As a proof of concept, the technique is used to experimentally characterize propagation loss and grating coupler response of Ge-on-Si waveguides at wavelengths from 6 to 10 µm. In addition, when the microscope is operated in scanning mode at fixed wavelength, the guided mode exiting the output facet is imaged with a lateral resolution better than 500 nm i.e. below the diffraction limit. The characterization technique can be applied to any mid-infrared waveguide platform and can provide non-destructive in-situ testing of discrete waveguide components.
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6
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Di Gaetano E, Watson S, McBrearty E, Sorel M, Paul DJ. Sub-megahertz linewidth 780.24 nm distributed feedback laser for 87Rb applications. Opt Lett 2020; 45:3529-3532. [PMID: 32630890 DOI: 10.1364/ol.394185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 05/25/2020] [Indexed: 06/11/2023]
Abstract
A distributed feedback GaAs-based semiconductor laser with a laterally coupled grating is demonstrated at a wavelength of 780.24 nm with up to 60 mW power. A mode expander and aluminum-free active layers have been used to reduce the linewidth to 612 kHz while maintaining high output power. The laser demonstrates over 40 dB side-mode suppression ratio with >0.3nm of tuning suitable for atom cooling experiments with the D2 87Rb atomic transition. This laser has substantial potential to be integrated into miniaturized cold atom systems.
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7
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Barzaghi A, Firoozabadi S, Salvalaglio M, Bergamaschini R, Ballabio A, Beyer A, Albani M, Valente J, Voigt A, Paul DJ, Miglio L, Montalenti F, Volz K, Isella G. Self-Assembly of Nanovoids in Si Microcrystals Epitaxially Grown on Deeply Patterned Substrates. Cryst Growth Des 2020; 20:2914-2920. [PMID: 33828439 PMCID: PMC8016367 DOI: 10.1021/acs.cgd.9b01312] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 04/08/2020] [Indexed: 06/11/2023]
Abstract
We present an experimental and theoretical analysis of the formation of nanovoids within Si microcrystals epitaxially grown on Si patterned substrates. The growth conditions leading to the nucleation of nanovoids have been highlighted, and the roles played by the deposition rate, substrate temperature, and substrate pattern geometry are identified. By combining various scanning and transmission electron microscopy techniques, it has been possible to link the appearance pits of a few hundred nanometer width at the microcrystal surface with the formation of nanovoids within the crystal volume. A phase-field model, including surface diffusion and the flux of incoming material with shadowing effects, reproduces the qualitative features of the nanovoid formation thereby opening new perspectives for the bottom-up fabrication of 3D semiconductors microstructures.
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Affiliation(s)
- Andrea Barzaghi
- L-NESS,
Dipartimento di Fisica, Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
| | - Saleh Firoozabadi
- Materials
Science Center and Faculty of Physics, Philipps-Universität
Marburg, Hans-Meerweinstraße 6, 35032 Marburg, Germany
| | - Marco Salvalaglio
- Institute
of Scientific Computing, Technische Universität
Dresden, 01062 Dresden, Germany
- Dresden
Center for Computational Materials Science, Technische Universität Dresden, 01062 Dresden, Germany
| | - Roberto Bergamaschini
- L-NESS
and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, I-20125 Milano, Italy
| | - Andrea Ballabio
- L-NESS,
Dipartimento di Fisica, Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
| | - Andreas Beyer
- Materials
Science Center and Faculty of Physics, Philipps-Universität
Marburg, Hans-Meerweinstraße 6, 35032 Marburg, Germany
| | - Marco Albani
- L-NESS
and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, I-20125 Milano, Italy
| | - Joao Valente
- James Watt
School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
| | - Axel Voigt
- Institute
of Scientific Computing, Technische Universität
Dresden, 01062 Dresden, Germany
- Dresden
Center for Computational Materials Science, Technische Universität Dresden, 01062 Dresden, Germany
| | - Douglas J. Paul
- James Watt
School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
| | - Leo Miglio
- L-NESS
and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, I-20125 Milano, Italy
| | - Francesco Montalenti
- L-NESS
and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, I-20125 Milano, Italy
| | - Kerstin Volz
- Materials
Science Center and Faculty of Physics, Philipps-Universität
Marburg, Hans-Meerweinstraße 6, 35032 Marburg, Germany
| | - Giovanni Isella
- L-NESS,
Dipartimento di Fisica, Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
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8
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Ciano C, Virgilio M, Bagolini L, Baldassarre L, Pashkin A, Helm M, Montanari M, Persichetti L, Di Gaspare L, Capellini G, Paul DJ, Scalari G, Faist J, De Seta M, Ortolani M. Terahertz absorption-saturation and emission from electron-doped germanium quantum wells. Opt Express 2020; 28:7245-7258. [PMID: 32225957 DOI: 10.1364/oe.381471] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 01/06/2020] [Indexed: 06/10/2023]
Abstract
We study radiative relaxation at terahertz frequencies in n-type Ge/SiGe quantum wells, optically pumped with a terahertz free electron laser. Two wells coupled through a tunneling barrier are designed to operate as a three-level laser system with non-equilibrium population generated by optical pumping around the 1→3 intersubband transition at 10 THz. The non-equilibrium subband population dynamics are studied by absorption-saturation measurements and compared to a numerical model. In the emission spectroscopy experiment, we observed a photoluminescence peak at 4 THz, which can be attributed to the 3→2 intersubband transition with possible contribution from the 2→1 intersubband transition. These results represent a step towards silicon-based integrated terahertz emitters.
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9
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Gallacher K, Ortolani M, Rew K, Ciano C, Baldassarre L, Virgilio M, Scalari G, Faist J, Di Gaspare L, De Seta M, Capellini G, Grange T, Birner S, Paul DJ. Design and simulation of losses in Ge/SiGe terahertz quantum cascade laser waveguides. Opt Express 2020; 28:4786-4800. [PMID: 32121710 DOI: 10.1364/oe.384993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 01/24/2020] [Indexed: 06/10/2023]
Abstract
The waveguide losses from a range of surface plasmon and double metal waveguides for Ge/Si1-xGex THz quantum cascade laser gain media are investigated at 4.79 THz (62.6 μm wavelength). Double metal waveguides demonstrate lower losses than surface plasmonic guiding with minimum losses for a 10 μm thick active gain region with silver metal of 21 cm-1 at 300 K reducing to 14.5 cm-1 at 10 K. Losses for silicon foundry compatible metals including Al and Cu are also provided for comparison and to provide a guide for gain requirements to enable lasers to be fabricated in commercial silicon foundries. To allow these losses to be calculated for a range of designs, the complex refractive index of a range of nominally undoped Si1-xGex with x = 0.7, 0.8 and 0.9 and doped Ge heterolayers were extracted from Fourier transform infrared spectroscopy measurements between 0.1 and 10 THz and from 300 K down to 10 K. The results demonstrate losses comparable to similar designs of GaAs/AlGaAs quantum cascade laser plasmon waveguides indicating that a gain threshold of 15.1 cm-1 and 23.8 cm-1 are required to produce a 4.79 THz Ge/SiGe THz laser at 10 K and 300 K, respectively, for 2 mm long double metal waveguide quantum cascade lasers with facet coatings.
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10
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Griskeviciute U, Millar RW, Gallacher K, Valente J, Paul DJ. Ge-on-Si waveguides for sensing in the molecular fingerprint regime. Opt Express 2020; 28:5749-5757. [PMID: 32121790 DOI: 10.1364/oe.382356] [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: 11/06/2019] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
Low loss, single mode, Ge-on-Si rib waveguides are used to demonstrated optical sensing in the molecular fingerprint region of the mid-infrared spectrum. Sensing is carried out using two spin-coated films, with strong absorption in the mid-infrared. These films are used to calibrate the modal overlap with an analyte, and therefore experimentally demonstrate the potential for Ge-on-Si waveguides for mid-infrared sensing applications. The results are compared to Fourier transform infrared spectroscopy measurements. The advantage of waveguide spectroscopy is demonstrated in terms of the increased optical interaction, and a new multi-path length approach is demonstrated to improve the dynamic range, which is not possible with conventional FTIR or attenuated total reflection (ATR) measurements. These results highlight the potential for Ge-on-Si as an integrated sensing platform for healthcare, pollution monitoring and defence applications.
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11
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Sinclair M, Gallacher K, Sorel M, Bayley JC, McBrearty E, Millar RW, Hild S, Paul DJ. 1.4 million Q factor Si 3N 4 micro-ring resonator at 780 nm wavelength for chip-scale atomic systems. Opt Express 2020; 28:4010-4020. [PMID: 32122061 DOI: 10.1364/oe.381224] [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: 10/23/2019] [Accepted: 01/17/2020] [Indexed: 06/10/2023]
Abstract
A silicon nitride micro-ring resonator with a loaded Q factor of 1.4 × 106 at 780 nm wavelength is demonstrated on silicon substrates. This is due to the low propagation loss waveguides achieved by optimization of waveguide sidewall interactions and top cladding refractive index. Potential applications include laser frequency stabilization allowing for chip-scale atomic systems targeting the 87Rb atomic transition at 780.24 nm. The temperature dependent wavelength shift of the micro-ring was determined to be 13.1 pm/K indicating that a minimum temperature stability of less than ±15 mK is required for such devices for wavelength locking applications. If a polyurethane acrylate top cladding of an optimized thickness is used then the micro-ring could effectively be athermal, resulting in reduced footprint, power consumption, and cost of potential devices.
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12
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Kuzmenko K, Vines P, Halimi A, Collins RJ, Maccarone A, McCarthy A, Greener ZM, Kirdoda J, Dumas DCS, Llin LF, Mirza MM, Millar RW, Paul DJ, Buller GS. 3D LIDAR imaging using Ge-on-Si single-photon avalanche diode detectors. Opt Express 2020; 28:1330-1344. [PMID: 32121846 DOI: 10.1364/oe.383243] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 12/18/2019] [Indexed: 06/10/2023]
Abstract
We present a scanning light detection and ranging (LIDAR) system incorporating an individual Ge-on-Si single-photon avalanche diode (SPAD) detector for depth and intensity imaging in the short-wavelength infrared region. The time-correlated single-photon counting technique was used to determine the return photon time-of-flight for target depth information. In laboratory demonstrations, depth and intensity reconstructions were made of targets at short range, using advanced image processing algorithms tailored for the analysis of single-photon time-of-flight data. These laboratory measurements were used to predict the performance of the single-photon LIDAR system at longer ranges, providing estimations that sub-milliwatt average power levels would be required for kilometer range depth measurements.
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13
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Vines P, Kuzmenko K, Kirdoda J, Dumas DCS, Mirza MM, Millar RW, Paul DJ, Buller GS. High performance planar germanium-on-silicon single-photon avalanche diode detectors. Nat Commun 2019; 10:1086. [PMID: 30842439 PMCID: PMC6403241 DOI: 10.1038/s41467-019-08830-w] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [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: 09/27/2018] [Accepted: 01/31/2019] [Indexed: 11/24/2022] Open
Abstract
Single-photon detection has emerged as a method of choice for ultra-sensitive measurements of picosecond optical transients. In the short-wave infrared, semiconductor-based single-photon detectors typically exhibit relatively poor performance compared with all-silicon devices operating at shorter wavelengths. Here we show a new generation of planar germanium-on-silicon (Ge-on-Si) single-photon avalanche diode (SPAD) detectors for short-wave infrared operation. This planar geometry has enabled a significant step-change in performance, demonstrating single-photon detection efficiency of 38% at 125 K at a wavelength of 1310 nm, and a fifty-fold improvement in noise equivalent power compared with optimised mesa geometry SPADs. In comparison with InGaAs/InP devices, Ge-on-Si SPADs exhibit considerably reduced afterpulsing effects. These results, utilising the inexpensive Ge-on-Si platform, provide a route towards large arrays of efficient, high data rate Ge-on-Si SPADs for use in eye-safe automotive LIDAR and future quantum technology applications. By incorporating germanium, single-photon avalanche diode detectors using silicon-based platforms are applied to infrared light detection. Here, a cost-effective planar detector geometry is presented yielding high detection efficiency suitable for applications such as sparse photon imaging or LIDAR.
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Affiliation(s)
- Peter Vines
- Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - Kateryna Kuzmenko
- Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Jarosław Kirdoda
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK
| | - Derek C S Dumas
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK
| | - Muhammad M Mirza
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK
| | - Ross W Millar
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK
| | - Douglas J Paul
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK
| | - Gerald S Buller
- Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
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14
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Fischer MP, Riede A, Gallacher K, Frigerio J, Pellegrini G, Ortolani M, Paul DJ, Isella G, Leitenstorfer A, Biagioni P, Brida D. Plasmonic mid-infrared third harmonic generation in germanium nanoantennas. Light Sci Appl 2018; 7:106. [PMID: 30564312 PMCID: PMC6290006 DOI: 10.1038/s41377-018-0108-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 11/22/2018] [Accepted: 11/24/2018] [Indexed: 06/09/2023]
Abstract
We demonstrate third harmonic generation in plasmonic antennas consisting of highly doped germanium grown on silicon substrates and designed to be resonant in the mid-infrared frequency range that is inaccessible with conventional nonlinear plasmonic materials. Owing to the near-field enhancement, the result is an ultrafast, subdiffraction, coherent light source with a wavelength tunable between 3 and 5 µm, and ideally overlapping with the fingerprint region of molecular vibrations. To observe the nonlinearity in this challenging spectral window, a high-power femtosecond laser system equipped with parametric frequency conversion in combination with an all-reflective confocal microscope setup is employed. We demonstrate spatially resolved maps of the linear scattering cross section and the nonlinear emission of single isolated antenna structures. A clear third-order power dependence as well as mid-infrared emission spectra prove the nonlinear nature of the light emission. Simulations support the observed resonance length of the double-rod antenna and demonstrate that the field enhancement inside the antenna material is responsible for the nonlinear frequency mixing.
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Affiliation(s)
- Marco P. Fischer
- Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
| | - Aaron Riede
- Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
| | - Kevin Gallacher
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT UK
| | - Jacopo Frigerio
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
| | - Giovanni Pellegrini
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Michele Ortolani
- Department of Physics, Sapienza University of Rome, 00185 Rome, Italy
| | - Douglas J. Paul
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT UK
| | - Giovanni Isella
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
| | - Alfred Leitenstorfer
- Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
| | - Paolo Biagioni
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Daniele Brida
- Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
- Physics and Materials Science Research Unit, University of Luxembourg, 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg
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15
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Gallacher K, Millar RW, Griškevičiūte U, Baldassarre L, Sorel M, Ortolani M, Paul DJ. Low loss Ge-on-Si waveguides operating in the 8-14 µm atmospheric transmission window. Opt Express 2018; 26:25667-25675. [PMID: 30469665 DOI: 10.1364/oe.26.025667] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 08/19/2018] [Indexed: 06/09/2023]
Abstract
Germanium-on-silicon waveguides were modeled, fabricated and characterized at wavelengths ranging from 7.5 to 11 µm. Measured waveguide losses are below 5 dB/cm for both TE and TM polarization and reach values of ∼ 1 dB/cm for ≥ 10 µm wavelengths for the TE polarization. This work demonstrates experimentally for the first time that Ge-on-Si is a viable waveguide platform for sensing in the molecular fingerprint spectral region. Detailed modeling and analysis is presented to identify the various loss contributions, showing that with practical techniques losses below 1 dB/cm could be achieved across the full measurement range.
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16
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Middlemiss RP, Bramsiepe SG, Douglas R, Hild S, Hough J, Paul DJ, Samarelli A, Rowan S, Hammond GD. Microelectromechanical system gravimeters as a new tool for gravity imaging. Philos Trans A Math Phys Eng Sci 2018; 376:rsta.2017.0291. [PMID: 29661979 PMCID: PMC5915651 DOI: 10.1098/rsta.2017.0291] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/22/2017] [Indexed: 06/08/2023]
Abstract
A microelectromechanical system (MEMS) gravimeter has been manufactured with a sensitivity of 40 ppb in an integration time of 1 s. This sensor has been used to measure the Earth tides: the elastic deformation of the globe due to tidal forces. No such measurement has been demonstrated before now with a MEMS gravimeter. Since this measurement, the gravimeter has been miniaturized and tested in the field. Measurements of the free-air and Bouguer effects have been demonstrated by monitoring the change in gravitational acceleration measured while going up and down a lift shaft of 20.7 m, and up and down a local hill of 275 m. These tests demonstrate that the device has the potential to be a useful field-portable instrument. The development of an even smaller device is underway, with a total package size similar to that of a smartphone.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'.
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Affiliation(s)
- Richard P Middlemiss
- SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8SU, UK
| | - Steven G Bramsiepe
- SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8SU, UK
| | - Rebecca Douglas
- SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8SU, UK
| | - Stefan Hild
- SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8SU, UK
| | - James Hough
- SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8SU, UK
| | - Douglas J Paul
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK
| | - Antonio Samarelli
- SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8SU, UK
| | - Sheila Rowan
- SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8SU, UK
| | - Giles D Hammond
- SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8SU, UK
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Han G, Popuri SR, Greer HF, Zhang R, Ferre-Llin L, Bos JWG, Zhou W, Reece MJ, Paul DJ, Knox AR, Gregory DH. Topotactic anion-exchange in thermoelectric nanostructured layered tin chalcogenides with reduced selenium content. Chem Sci 2018; 9:3828-3836. [PMID: 29780515 PMCID: PMC5939836 DOI: 10.1039/c7sc05190e] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [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: 12/06/2017] [Accepted: 03/23/2018] [Indexed: 11/21/2022] Open
Abstract
Topotactic solution synthesis yields nanostructured tin chalcogenides, SnS1–xSex with controllable composition; spark plasma sintered SnS0.1Se0.9 achieves ZT ≈ 1.16 at 923 K via microstructural texture tuning.
Anion exchange has been performed with nanoplates of tin sulfide (SnS) via “soft chemical” organic-free solution syntheses to yield layered pseudo-ternary tin chalcogenides on a 10 g-scale. SnS undergoes a topotactic transformation to form a series of S-substituted tin selenide (SnSe) nano/micro-plates with tuneable chalcogenide composition. SnS0.1Se0.9 nanoplates were spark plasma sintered into phase-pure, textured, dense pellets, the ZT of which has been significantly enhanced to ≈1.16 from ≈0.74 at 923 K via microstructure texturing control. These approaches provide versatile, scalable and low-cost routes to p-type layered tin chalcogenides with controllable composition and competitive thermoelectric performance.
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Affiliation(s)
- Guang Han
- WestCHEM , School of Chemistry , University of Glasgow , Glasgow , G12 8QQ , UK .
| | - Srinivas R Popuri
- Institute of Chemical Sciences , Centre for Advanced Energy Storage and Recovery , School of Engineering and Physical Sciences , Heriot-Watt University , Edinburgh , EH14 4AS , UK
| | - Heather F Greer
- EaStCHEM , School of Chemistry , University of St Andrews , St Andrews , Fife KY16 9ST , UK
| | - Ruizhi Zhang
- School of Engineering & Materials Science , Queen Mary University of London , London , E1 4NS , UK
| | | | - Jan-Willem G Bos
- Institute of Chemical Sciences , Centre for Advanced Energy Storage and Recovery , School of Engineering and Physical Sciences , Heriot-Watt University , Edinburgh , EH14 4AS , UK
| | - Wuzong Zhou
- EaStCHEM , School of Chemistry , University of St Andrews , St Andrews , Fife KY16 9ST , UK
| | - Michael J Reece
- School of Engineering & Materials Science , Queen Mary University of London , London , E1 4NS , UK
| | - Douglas J Paul
- School of Engineering , University of Glasgow , Glasgow , G12 8LT , UK
| | - Andrew R Knox
- School of Engineering , University of Glasgow , Glasgow , G12 8LT , UK
| | - Duncan H Gregory
- WestCHEM , School of Chemistry , University of Glasgow , Glasgow , G12 8QQ , UK .
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18
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Middlemiss RP, Bramsiepe SG, Douglas R, Hough J, Paul DJ, Rowan S, Hammond GD. Field Tests of a Portable MEMS Gravimeter. Sensors (Basel) 2017; 17:s17112571. [PMID: 29117099 PMCID: PMC5713048 DOI: 10.3390/s17112571] [Citation(s) in RCA: 7] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 11/04/2017] [Accepted: 11/06/2017] [Indexed: 11/16/2022]
Abstract
Gravimeters are used to measure density anomalies under the ground. They are applied in many different fields from volcanology to oil and gas exploration, but present commercial systems are costly and massive. A new type of gravity sensor has been developed that utilises the same fabrication methods as those used to make mobile phone accelerometers. In this study, we describe the first results of a field-portable microelectromechanical system (MEMS) gravimeter. The stability of the gravimeter is demonstrated through undertaking a multi-day measurement with a standard deviation of 5.58×10−6 ms−2. It is then demonstrated that a change in gravitational acceleration of 4.5×10−5 ms−2 can be measured as the device is moved between the top and the bottom of a 20.7 m lift shaft with a signal-to-noise ratio (SNR) of 14.25. Finally, the device is demonstrated to be stable in a more harsh environment: a 4.5×10−4 ms−2 gravity variation is measured between the top and bottom of a 275-m hill with an SNR of 15.88. These initial field-tests are an important step towards a chip-sized gravity sensor.
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Affiliation(s)
- Richard P Middlemiss
- University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8SU, UK.
| | - Steven G Bramsiepe
- University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8SU, UK.
| | - Rebecca Douglas
- University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8SU, UK.
| | - James Hough
- University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8SU, UK.
| | - Douglas J Paul
- University of Glasgow, School of Engineering, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK.
| | - Sheila Rowan
- University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8SU, UK.
| | - Giles D Hammond
- University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8SU, UK.
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Millar RW, Dumas DCS, Gallacher KF, Jahandar P, MacGregor C, Myronov M, Paul DJ. Mid-infrared light emission > 3 µm wavelength from tensile strained GeSn microdisks. Opt Express 2017; 25:25374-25385. [PMID: 29041205 DOI: 10.1364/oe.25.025374] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 09/21/2017] [Indexed: 06/07/2023]
Abstract
GeSn alloys with Sn contents of 8.4 % and 10.7 % are grown pseudomorphically on Ge buffers on Si (001) substrates. The alloys as-grown are compressively strained, and therefore indirect bandgap. Undercut GeSn on Ge microdisk structures are fabricated and strained by silicon nitride stressor layers, which leads to tensile strain in the alloys, and direct bandgap photoluminescence in the 3-5 µm gas sensing window of the electromagnetic spectrum. The use of pseudomorphic layers and external stress mitigates the need for plastic deformation to obtain direct bandgap alloys. It is demonstrated, that the optically pumped light emission overlaps with the methane absorption lines, suggesting that GeSn alloys are well suited for mid-infrared integrated gas sensors on Si chips.
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20
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Mirza MM, Schupp FJ, Mol JA, MacLaren DA, Briggs GAD, Paul DJ. One dimensional transport in silicon nanowire junction-less field effect transistors. Sci Rep 2017; 7:3004. [PMID: 28592820 PMCID: PMC5462787 DOI: 10.1038/s41598-017-03138-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [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: 01/10/2017] [Accepted: 04/25/2017] [Indexed: 11/09/2022] Open
Abstract
Junction-less nanowire transistors are being investigated to solve short channel effects in future CMOS technology. Here we demonstrate 8 nm diameter silicon nanowire junction-less transistors with metallic doping densities which demonstrate clear 1D electronic transport characteristics. The 1D regime allows excellent gate modulation with near ideal subthreshold slopes, on- to off-current ratios above 108 and high on-currents at room temperature. Universal conductance scaling as a function of voltage and temperature similar to previous reports of Luttinger liquids and Coulomb gap behaviour at low temperatures suggests that many body effects including electron-electron interactions are important in describing the electronic transport. This suggests that modelling of such nanowire devices will require 1D models which include many body interactions to accurately simulate the electronic transport to optimise the technology but also suggest that 1D effects could be used to enhance future transistor performance.
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Affiliation(s)
- Muhammad M Mirza
- University of Glasgow, School of Engineering, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK
| | - Felix J Schupp
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
| | - Jan A Mol
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
| | - Donald A MacLaren
- University of Glasgow, SUPA School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK
| | - G Andrew D Briggs
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
| | - Douglas J Paul
- University of Glasgow, School of Engineering, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK.
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21
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Fischer MP, Schmidt C, Sakat E, Stock J, Samarelli A, Frigerio J, Ortolani M, Paul DJ, Isella G, Leitenstorfer A, Biagioni P, Brida D. Optical Activation of Germanium Plasmonic Antennas in the Mid-Infrared. Phys Rev Lett 2016; 117:047401. [PMID: 27494498 DOI: 10.1103/physrevlett.117.047401] [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] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Indexed: 06/06/2023]
Abstract
Impulsive interband excitation with femtosecond near-infrared pulses establishes a plasma response in intrinsic germanium structures fabricated on a silicon substrate. This direct approach activates the plasmonic resonance of the Ge structures and enables their use as optical antennas up to the mid-infrared spectral range. The optical switching lasts for hundreds of picoseconds until charge recombination redshifts the plasma frequency. The full behavior of the structures is modeled by the electrodynamic response established by an electron-hole plasma in a regular array of antennas.
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Affiliation(s)
- Marco P Fischer
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - Christian Schmidt
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - Emilie Sakat
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Johannes Stock
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - Antonio Samarelli
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
| | - Jacopo Frigerio
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
| | - Michele Ortolani
- Department of Physics, Sapienza University of Rome, Rome 00185, Italy
| | - Douglas J Paul
- School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
| | - Giovanni Isella
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
| | - Alfred Leitenstorfer
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - Paolo Biagioni
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Daniele Brida
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
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22
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Middlemiss RP, Samarelli A, Paul DJ, Hough J, Rowan S, Hammond GD. Measurement of the Earth tides with a MEMS gravimeter. Nature 2016; 531:614-7. [PMID: 27029276 DOI: 10.1038/nature17397] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 02/02/2016] [Indexed: 11/09/2022]
Abstract
The ability to measure tiny variations in the local gravitational acceleration allows, besides other applications, the detection of hidden hydrocarbon reserves, magma build-up before volcanic eruptions, and subterranean tunnels. Several technologies are available that achieve the sensitivities required for such applications (tens of microgal per hertz(1/2)): free-fall gravimeters, spring-based gravimeters, superconducting gravimeters, and atom interferometers. All of these devices can observe the Earth tides: the elastic deformation of the Earth's crust as a result of tidal forces. This is a universally predictable gravitational signal that requires both high sensitivity and high stability over timescales of several days to measure. All present gravimeters, however, have limitations of high cost (more than 100,000 US dollars) and high mass (more than 8 kilograms). Here we present a microelectromechanical system (MEMS) device with a sensitivity of 40 microgal per hertz(1/2) only a few cubic centimetres in size. We use it to measure the Earth tides, revealing the long-term stability of our instrument compared to any other MEMS device. MEMS accelerometers--found in most smart phones--can be mass-produced remarkably cheaply, but none are stable enough to be called a gravimeter. Our device has thus made the transition from accelerometer to gravimeter. The small size and low cost of this MEMS gravimeter suggests many applications in gravity mapping. For example, it could be mounted on a drone instead of low-flying aircraft for distributed land surveying and exploration, deployed to monitor volcanoes, or built into multi-pixel density-contrast imaging arrays.
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Affiliation(s)
- R P Middlemiss
- Scottish Universities Physics Alliance (SUPA), University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8QQ, UK.,University of Glasgow, School of Engineering, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK
| | - A Samarelli
- Scottish Universities Physics Alliance (SUPA), University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8QQ, UK
| | - D J Paul
- University of Glasgow, School of Engineering, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK
| | - J Hough
- Scottish Universities Physics Alliance (SUPA), University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8QQ, UK
| | - S Rowan
- Scottish Universities Physics Alliance (SUPA), University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8QQ, UK
| | - G D Hammond
- Scottish Universities Physics Alliance (SUPA), University of Glasgow, School of Physics and Astronomy, Kelvin Building, University Avenue, Glasgow G12 8QQ, UK
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23
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Han G, Popuri SR, Greer HF, Bos JWG, Zhou W, Knox AR, Montecucco A, Siviter J, Man EA, Macauley M, Paul DJ, Li WG, Paul MC, Gao M, Sweet T, Freer R, Azough F, Baig H, Sellami N, Mallick TK, Gregory DH. Facile Surfactant-Free Synthesis of p-Type SnSe Nanoplates with Exceptional Thermoelectric Power Factors. Angew Chem Int Ed Engl 2016; 55:6433-7. [PMID: 27094703 PMCID: PMC5074331 DOI: 10.1002/anie.201601420] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 03/23/2016] [Indexed: 11/09/2022]
Abstract
A surfactant‐free solution methodology, simply using water as a solvent, has been developed for the straightforward synthesis of single‐phase orthorhombic SnSe nanoplates in gram quantities. Individual nanoplates are composed of {100} surfaces with {011} edge facets. Hot‐pressed nanostructured compacts (Eg≈0.85 eV) exhibit excellent electrical conductivity and thermoelectric power factors (S2σ) at 550 K. S2σ values are 8‐fold higher than equivalent materials prepared using citric acid as a structure‐directing agent, and electrical properties are comparable to the best‐performing, extrinsically doped p‐type polycrystalline tin selenides. The method offers an energy‐efficient, rapid route to p‐type SnSe nanostructures.
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Affiliation(s)
- Guang Han
- WestCHEM, School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Srinivas R Popuri
- Institute of Chemical Sciences and Centre for Advanced Energy Storage & Recovery, School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Heather F Greer
- EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - Jan-Willem G Bos
- Institute of Chemical Sciences and Centre for Advanced Energy Storage & Recovery, School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Wuzong Zhou
- EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - Andrew R Knox
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | | | - Jonathan Siviter
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Elena A Man
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Martin Macauley
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Douglas J Paul
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Wen-Guang Li
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Manosh C Paul
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Min Gao
- School of Engineering, Cardiff University, Cardiff, CF24 3AA, UK
| | - Tracy Sweet
- School of Engineering, Cardiff University, Cardiff, CF24 3AA, UK
| | - Robert Freer
- Materials Science Centre, School of Materials, University of Manchester, Manchester, M13 9PL, UK
| | - Feridoon Azough
- Materials Science Centre, School of Materials, University of Manchester, Manchester, M13 9PL, UK
| | - Hasan Baig
- Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Nazmi Sellami
- Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Tapas K Mallick
- Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Duncan H Gregory
- WestCHEM, School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK.
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24
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Millar RW, Gallacher K, Frigerio J, Ballabio A, Bashir A, MacLaren I, Isella G, Paul DJ. Analysis of Ge micro-cavities with in-plane tensile strains above 2. Opt Express 2016; 24:4365-4374. [PMID: 29092264 DOI: 10.1364/oe.24.004365] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ge on Si micro-disk, ring and racetrack cavities are fabricated and strained using silicon nitride stressor layers. Photoluminescence measurements demonstrate emission at wavelengths ≥ 2.3 μm, and the highest strained samples demonstrate in-plane, tensile strains of > 2 %, as measured by Raman spectroscopy. Strain analysis of the micro-disk structures demonstrate that shear strains are present in circular cavities, which can detrimentally effect the carrier concentration for direct band transitions. The advantages and disadvantages of each type of proposed cavity structure are discussed.
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25
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Baldassarre L, Sakat E, Frigerio J, Samarelli A, Gallacher K, Calandrini E, Isella G, Paul DJ, Ortolani M, Biagioni P. Midinfrared Plasmon-Enhanced Spectroscopy with Germanium Antennas on Silicon Substrates. Nano Lett 2015; 15:7225-7231. [PMID: 26457387 DOI: 10.1021/acs.nanolett.5b03247] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Midinfrared plasmonic sensing allows the direct targeting of unique vibrational fingerprints of molecules. While gold has been used almost exclusively so far, recent research has focused on semiconductors with the potential to revolutionize plasmonic devices. We fabricate antennas out of heavily doped Ge films epitaxially grown on Si wafers and demonstrate up to 2 orders of magnitude signal enhancement for the molecules located in the antenna hot spots compared to those located on a bare silicon substrate. Our results set a new path toward integration of plasmonic sensors with the ubiquitous CMOS platform.
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Affiliation(s)
- Leonetta Baldassarre
- Dipartimento di Fisica, Università di Roma "La Sapienza" , Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia , Viale Regina Elena 291, I-00161 Roma, Italy
| | - Emilie Sakat
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Jacopo Frigerio
- LNESS, Dipartimento di Fisica del Politecnico di Milano, polo di Como , via Anzani 42, I-22100 Como, Italy
| | - Antonio Samarelli
- School of Engineering, University of Glasgow , Rankine Building, Oakfield Avenue, Glasgow G12 8LT, U.K
| | - Kevin Gallacher
- School of Engineering, University of Glasgow , Rankine Building, Oakfield Avenue, Glasgow G12 8LT, U.K
| | - Eugenio Calandrini
- Dipartimento di Fisica, Università di Roma "La Sapienza" , Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Giovanni Isella
- LNESS, Dipartimento di Fisica del Politecnico di Milano, polo di Como , via Anzani 42, I-22100 Como, Italy
| | - Douglas J Paul
- School of Engineering, University of Glasgow , Rankine Building, Oakfield Avenue, Glasgow G12 8LT, U.K
| | - Michele Ortolani
- Dipartimento di Fisica, Università di Roma "La Sapienza" , Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Paolo Biagioni
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
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26
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Millar RW, Gallacher K, Samarelli A, Frigerio J, Chrastina D, Isella G, Dieing T, Paul DJ. Extending the emission wavelength of Ge nanopillars to 2.25 μm using silicon nitride stressors. Opt Express 2015; 23:18193-18202. [PMID: 26191877 DOI: 10.1364/oe.23.018193] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The room temperature photoluminescence from Ge nanopillars has been extended from 1.6 μm to above 2.25 μm wavelength through the application of tensile stress from silicon nitride stressors deposited by inductively-coupled-plasma plasma-enhanced chemical-vapour-deposition. Photoluminescence measurements demonstrate biaxial equivalent tensile strains of up to ∼ 1.35% in square topped nanopillars with side lengths of 200 nm. Biaxial equivalent strains of 0.9% are observed in 300 nm square top pillars, confirmed by confocal Raman spectroscopy. Finite element modelling demonstrates that an all-around stressor layer is preferable to a top only stressor, as it increases the hydrostatic component of the strain, leading to an increased shift in the band-edge and improved uniformity over top-surface only stressors layers.
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27
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Busche C, Vilà-Nadal L, Yan J, Miras HN, Long DL, Georgiev VP, Asenov A, Pedersen RH, Gadegaard N, Mirza MM, Paul DJ, Poblet JM, Cronin L. Design and fabrication of memory devices based on nanoscale polyoxometalate clusters. Nature 2014; 515:545-9. [PMID: 25409147 DOI: 10.1038/nature13951] [Citation(s) in RCA: 200] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 10/08/2014] [Indexed: 02/07/2023]
Abstract
Flash memory devices--that is, non-volatile computer storage media that can be electrically erased and reprogrammed--are vital for portable electronics, but the scaling down of metal-oxide-semiconductor (MOS) flash memory to sizes of below ten nanometres per data cell presents challenges. Molecules have been proposed to replace MOS flash memory, but they suffer from low electrical conductivity, high resistance, low device yield, and finite thermal stability, limiting their integration into current MOS technologies. Although great advances have been made in the pursuit of molecule-based flash memory, there are a number of significant barriers to the realization of devices using conventional MOS technologies. Here we show that core-shell polyoxometalate (POM) molecules can act as candidate storage nodes for MOS flash memory. Realistic, industry-standard device simulations validate our approach at the nanometre scale, where the device performance is determined mainly by the number of molecules in the storage media and not by their position. To exploit the nature of the core-shell POM clusters, we show, at both the molecular and device level, that embedding [(Se(IV)O3)2](4-) as an oxidizable dopant in the cluster core allows the oxidation of the molecule to a [Se(v)2O6](2-) moiety containing a {Se(V)-Se(V)} bond (where curly brackets indicate a moiety, not a molecule) and reveals a new 5+ oxidation state for selenium. This new oxidation state can be observed at the device level, resulting in a new type of memory, which we call 'write-once-erase'. Taken together, these results show that POMs have the potential to be used as a realistic nanoscale flash memory. Also, the configuration of the doped POM core may lead to new types of electrical behaviour. This work suggests a route to the practical integration of configurable molecules in MOS technologies as the lithographic scales approach the molecular limit.
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Affiliation(s)
- Christoph Busche
- WestCHEM, School of Chemistry, The University of Glasgow, Glasgow G12 8QQ, UK
| | - Laia Vilà-Nadal
- WestCHEM, School of Chemistry, The University of Glasgow, Glasgow G12 8QQ, UK
| | - Jun Yan
- WestCHEM, School of Chemistry, The University of Glasgow, Glasgow G12 8QQ, UK
| | - Haralampos N Miras
- WestCHEM, School of Chemistry, The University of Glasgow, Glasgow G12 8QQ, UK
| | - De-Liang Long
- WestCHEM, School of Chemistry, The University of Glasgow, Glasgow G12 8QQ, UK
| | - Vihar P Georgiev
- School of Engineering, The University of Glasgow, Glasgow G12 8LT, UK
| | - Asen Asenov
- School of Engineering, The University of Glasgow, Glasgow G12 8LT, UK
| | - Rasmus H Pedersen
- School of Engineering, The University of Glasgow, Glasgow G12 8LT, UK
| | - Nikolaj Gadegaard
- School of Engineering, The University of Glasgow, Glasgow G12 8LT, UK
| | - Muhammad M Mirza
- School of Engineering, The University of Glasgow, Glasgow G12 8LT, UK
| | - Douglas J Paul
- School of Engineering, The University of Glasgow, Glasgow G12 8LT, UK
| | - Josep M Poblet
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo street, 43007 Tarragona, Spain
| | - Leroy Cronin
- WestCHEM, School of Chemistry, The University of Glasgow, Glasgow G12 8QQ, UK
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Mirza MM, MacLaren DA, Samarelli A, Holmes BM, Zhou H, Thoms S, MacIntyre D, Paul DJ. Determining the electronic performance limitations in top-down-fabricated Si nanowires with mean widths down to 4 nm. Nano Lett 2014; 14:6056-6060. [PMID: 25299791 DOI: 10.1021/nl5015298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Silicon nanowires have been patterned with mean widths down to 4 nm using top-down lithography and dry etching. Performance-limiting scattering processes have been measured directly which provide new insight into the electronic conduction mechanisms within the nanowires. Results demonstrate a transition from 3-dimensional (3D) to 2D and then 1D as the nanowire mean widths are reduced from 12 to 4 nm. The importance of high quality surface passivation is demonstrated by a lack of significant donor deactivation, resulting in neutral impurity scattering ultimately limiting the electronic performance. The results indicate the important parameters requiring optimization when fabricating nanowires with atomic dimensions.
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Affiliation(s)
- Muhammad M Mirza
- School of Engineering, University of Glasgow , Rankine Building, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
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Dumas DCS, Gallacher K, Rhead S, Myronov M, Leadley DR, Paul DJ. Ge/SiGe quantum confined Stark effect electro-absorption modulation with low voltage swing at λ = 1550 nm. Opt Express 2014; 22:19284-19292. [PMID: 25321013 DOI: 10.1364/oe.22.019284] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Low-voltage swing (≤1.0 V) high-contrast ratio (6 dB) electro-absorption modulation covering 1460 to 1560 nm wavelength has been demonstrated using Ge/SiGe quantum confined Stark effect (QCSE) diodes grown on a silicon substrate. The heterolayers for the devices were designed using an 8-band k.p Poisson-Schrödinger solver which demonstrated excellent agreement with the experimental results. Modelling and experimental results demonstrate that by changing the quantum well width of the device, low power Ge/SiGe QCSE modulators can be designed to cover the S- and C-telecommunications bands.
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Affiliation(s)
- David R. S. Cumming
- School of Engineering, University of Glasgow, James Watt South Building, Glasgow G12 8QQ, UK
| | - Stephen B. Furber
- School of Computer Science, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Douglas J. Paul
- School of Engineering, University of Glasgow, James Watt South Building, Glasgow G12 8QQ, UK
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Paul DJ. Effects of smoking and unsafe alcohol consumption on aboriginal life expectancy. Med J Aust 1998; 169:119-20. [PMID: 9700355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Paul DJ, Cleaver JR, Ahmed H, Whall TE. Cotunneling of holes in silicon-based structures. Phys Rev B Condens Matter 1994; 49:16514-16517. [PMID: 10010803 DOI: 10.1103/physrevb.49.16514] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Abstract
The surface morphology of transplants of rat fetal hippocampal tissue, and of cavities formed by aspiration lesion of the adult rat hippocampus and overlying neocortex into which the transplants were placed, was studied by scanning electron microscopy. The surface of lesion cavities was covered by a scar upon which occasional cellular profiles were found. The surface cells resembled supraependymal macrophages. Lesion cavities with a transplant showed similar scarring although the number of supraependymal structures was increased. Polymorphic cells and numerous fiber processes were observed both on the surface and embedded in the scar. Ependymal structures were seen on the non-damaged ventricular surfaces adjacent to the lesion site. These regions, however, also displayed increases in the number and types of supraependymal structures. Scanning electron microscopy demonstrated considerable variability in surface morphology of different transplants and over the surface of individual transplants. A transplant could show regions of scarring, areas covered by cells resembling ependymal cells, and regions covered by a dense matrix of fibers. In many regions the fibers coalesced to form a branching, web-like network over the transplant surface. Transmission electron microscopy indicated that the surface could be covered by ependymal cells or by the scar seen in scanning specimens. Some surface fibers were identified as axons. Cells on the surface of the transplants could be identified as neuronal, glial-like, and phagocytic. The cells and the possible effects of surface morphology on transplant function is discussed.
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Affiliation(s)
- R H Baisden
- Department of Anatomy, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614
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Abstract
The effects of clonidine, a central alpha 2 agonist, on changes in blood pressure caused by muscle afferent nerve (ergoreceptor) activation and baroreceptor manipulation were studied in cats. Prolonged isometric contractions (ergoreceptor activation) of the gastrocnemius and plantaris muscles increased mean arterial pressure by 53 mmHg. This pressor response was not altered by naloxone (0.5 mumol.litre-1) but was eliminated by clonidine (0.5-2.0 micrograms) when injected into the cerebral aqueduct. Brief occlusion of the carotid artery (15-30 s) caused mean arterial pressure to increase by 32-42 mmHg at rest. Neither naloxone nor clonidine altered the magnitude of the reflex pressor response to carotid occlusion. Similar increases in pressure were measured when occlusion was applied during fatiguing isometric contractions; thus baroreceptor induced increases in pressure were superimposed on the ergoreceptor induced blood pressure changes. Naloxone did not affect the changes in pressure caused by either reflex response. Clonidine continued to eliminate the pressor response to muscular contraction but did not affect the pressure increase when the carotid occlusion was applied during contractions. Electrical stimulation of the carotid sinus nerve caused blood pressure to decrease by 36 mmHg during rest and by 41 mmHg during fatiguing isometric contractions. Clonidine did not alter the depressor response to carotid sinus nerve stimulation. These data may indicate that separate pathways centrally mediate the changes in blood pressure caused by ergoreceptor and baroreceptor afferent activation. The integration of the ergoreceptor pathway may involve a catecholaminergic-opioidergic system but the present results do not suggest a similar interaction for the baroreceptor integration.
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Affiliation(s)
- D P Sparks
- Department of Physiology, College of Medicine, East Tennessee State University, Johnson City 37614
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Abstract
The effects of an alpha 2 adrenoceptor blocker, yohimbine, and an alpha 1 adrenoceptor blocker, phenoxybenzamine, and the central alpha 2 adrenoceptor agonist, clonidine, on changes in arterial blood pressure and heart rate were studied during fatiguing muscular contractions to determine whether an adrenergic-opioidergic system might be involved in the mediation of cardiovascular function. Fatiguing contractions of the gastrocnemius and plantaris muscles of cats caused an increase in mean arterial blood pressure to 150-170 mmHg from resting values of 110-120 mmHg. Injection of clonidine into the cerebral aqueduct eliminated the increase in blood pressure; this effect was dose dependent. Naloxone antagonised the effects of the highest dose of clonidine (5 micrograms). Injections of yohimbine (1 microgram) into the cerebral aqueduct had no significant effect on this pressor response. Yohimbine (1 microgram) effectively counteracted the antipressor effects of clonidine when the two drugs were injected together until higher doses of clonidine (2-5 micrograms) were used. Phenoxybenzamine had no effect on the pressor response itself but unlike yohimbine was able to attenuate the effects of clonidine only when injected together. These data suggest that activation of muscle ergoreceptor afferent nerve fibres (group III and IV fibres) during muscular contractions may cause an increase in arterial blood pressure by interfering with an inhibitory adrenergic-endorphinergic pathway in the medullary region of the brainstem.
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Affiliation(s)
- C A Williams
- Department of Physiology, College of Medicine, East Tennessee State University, Johnson City 37614
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Abstract
Six episodes of contrast extravasation occurred in 5 patients during intravenous digital subtraction angiography in a period of 9 months. The extravasations were into the mediastinum (3), pericardium (1), and right atrial wall (2). These occurred using a variety of catheters, all the same size (5.0 F--1.67 mm). Three were Katzen catheters, one had a pigtail configuration, and two were straight catheters. We believe that the extravasations are due to three main factors. The first is catheter-related, owing to the small size (5.0 F) creating recoil and marked jet stream effect due to the large volume and pressure that must be delivered through the side holes. The second factor is related to positioning of the catheter in the superior vena cava. Finally, the respiratory phase at the time of injection becomes crucial. Understanding of these factors may help to decrease this potentially serious complication.
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Adam W, Johnson JC, Paul DJ, Clausen K, Schuller DE. Primary adenocarcinoma of the middle ear. AJNR Am J Neuroradiol 1982; 3:674-6. [PMID: 6816047 PMCID: PMC8333797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Lloyd TV, Paul DJ, Arbona G. Lymphocele: an unusual mass in the right upper quadrant. South Med J 1980; 73:380-1. [PMID: 7361153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A patient with a palpable right upper abdominal mass eight years after cholecystectomy was found to have a subhepatic lymphocele. Although this is an uncommon location, the presence of a sonolucent mass in an area of previous surgery suggests lymphocele.
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Abstract
A lipoma eroding the scapula is diagnosed by computed tomography.
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Paul DJ, Lloyd TV. Hindgut duplication with rectovaginal fistula. Obstet Gynecol 1979; 54:390-2. [PMID: 471389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Complete colon duplication is an extremely rare congenital anomaly that occasionally presents diagnostic problems. This report presents a 23-year-old black woman with complete duplication of the colon and distal ileum, with termination of 1 colon into the vagina.
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Paul DJ, Gilday DL. Polyphosphate bone scanning of non-malignant bone disease in children. J Can Assoc Radiol 1975; 26:285-90. [PMID: 1223126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The advent of 99mTechnetium phosphate bone scanning radiopharmaceuticals has opened new methods of investigation of pediatric bone diseases. In axial skeleton pain, suspected osteomyelitis, evaluation of vascular integrity and suspected but undetected fractures, the bone scan has proved to be a highly complementary study to the radiologic examination.
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Abstract
Differentiation of osteomyelitis from cellulitis or septic arthritis can be difficult. The radiological examination often does not have the characteristic features. Seventy of 71 children with osteomyelitis had focal areas of increased radioactivity at the site of the infection. The addition of "blood pool" images aids in the interpretation of the study as they permit evaluation of the effect of hyperemia. The 13 childrenwith cellulitis had diffuse increase in radioactivity involving both the bones and soft tissues. Bone imaging as the initial screening procedure for osteomyelitis is recommended.
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