David Cox

Dr David Cox


Senior Research Fellow
+44 (0)1483 682297
19 ATI 02

Academic and research departments

Advanced Technology Institute.

Biography

University roles and responsibilities

  • Responsible for the upkeep, and maintenance of the Focused Ion beam laboratories.

    Research

    Research interests

    My publications

    Publications

    RC Smith, JD Carey, CHP Poa, DC Cox, SRP Silva (2004)Electron field emission from room temperature grown carbon nanofibers, In: JOURNAL OF APPLIED PHYSICS95(6)pp. 3153-3157 AMER INST PHYSICS

    The field induced emission from room temperature grown carbon nanofibers at low macroscopic electric field was discussed. It was found that the nanofiber were deposited using methane as a source gas in a conventional rf plasma enhanced chemical vapor deposition reactor. It was observed that nanofibers possessed an average diameter of 300 nm. Analysis shows that the mechanism for emission at low fields was attributed to field enhancement at the tips.

    MT Langridge, DC Cox, RP Webb, V Stolojan (2014)The fabrication of aspherical microlenses using focused ion-beam techniques, In: MICRON57pp. 56-66 PERGAMON-ELSEVIER SCIENCE LTD
    Jose Anguita, David Cox, Muhammad Ahmad, YY Tan, Jeremy Allam, S Silva (2013)Highly transmissive carbon nanotube forests grown at low substrate temperature, In: Advanced Functional Materials23(44)pp. 5502-5509 Wiley

    Despite the "darker than black" association attributed to carbon nanotube forests, here is shown that it is also possible to grow these structures, over heat-sensitive substrates, featuring highly transmissive characteristics from the UV to infrared wavelengths, for forest heights as high as 20 μm. The optical transmission is interpreted in terms of light propagation along channels that are self-generated by localized bundling of tubes, acting as waveguides. A good correlation is shown between the distribution of diameter sizes of these sub-wavelength voids and the transmission spectrum of the forests. For the shorter visible and near-UV wavelengths, this model shows that light propagates by channeling along individual vertical voids in the forests, which elucidates the origin for the widely-reported near-zero reflectance values observed in forests. For the longer infrared wavelengths, the mode spreads over many nanotubes and voids, and propagates along a "homogeneous effective medium". The strong absorption of the forest at the shorter wavelengths is correlated in terms of the stronger attenuation inside a waveguide cavity, according to the λ attenuation dependency of standard waveguide theory. The realization of this material can lead to novel avenues in new optoelectronic device design, where the carbon nanotube forests can be used as highly conducting "scaffolds" for optically active materials, whilst also allowing light to penetrate to significant depths into the structure, in excess of 20 μm, enabling optical functionality. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

    RC Smith, JD Carey, DC Cox, SRP Silva (2006)In situ electrode manipulation for three terminal field emission characterization of individual carbon nanotubes, In: APPLIED PHYSICS LETTERS89(6)ARTN 0 AMER INST PHYSICS

    In situ three terminal electron field emission characterization of an isolated multiwalled carbon nanotube has been performed, where both anode and gate electrodes are attached to high precision piezodrivers. All measurements are performed in a scanning electron microscope allowing accurate knowledge of the local environment of the nanotube to be obtained. It is shown that the presence of the grounded gate electrode screens the applied field by approximately 32%. This technique in positioning the gate and anode electrodes allows for an estimate of the gate transparency factor and demonstrates characterization of individual carbon nanotubes without the need for fabrication of arrays of emitters.

    RC Smith, David Cox, S Silva (2005)Electron field emission from a single carbon nanotube: Effects of anode location, In: APPLIED PHYSICS LETTERS87(10)103112 AMER INST PHYSICS

    Electron field emission from an isolated carbon nanotube (CNT) was performed in situ in a modified scanning electron microscope, over a range of anode to CNT tip separations, D, of 1-60 mu m. The threshold field required for an emission current of 100 nA was seen to decrease from a value of 42 V mu m(-1) at an anode to CNT tip separation of 1 mu m, asymptotically, to approach 4 V mu m(-1) at a separation of 60 mu m. It is proposed that at low D, the electric field enhancement factor (beta) reduces as the anode electrode approaches the CNT mimicking a parallel plate configuration. Under "far field" conditions, where D > 3 h, where h is the CNT height, the CNT enhancement factor is no longer dependant on D, as shown by the asymptotic behavior of the threshold field, and is purely a factor of the CNT height and radius. For each CNT to tip separation, measured emission current data together with the threshold field and enhancement, are consistent with a Fowler-Nordheim analysis for the far field conditions, and dispels the need for a novel emission mechanism to explain the results as has been proposed recently. (c) 2005 American Institute of Physics.

    S. R. P. Silva, JD Carey, G. Y. Chen, D. C. Cox, R. D. Forrest, C. H. Poa, R. C. Smith, Y. F. Tang, J. M. Shannon (2004)Nanoengineering of materials for field emission display technologies, In: IEE Proceedings in Circuits, Devices and Systems51pp. 489-496

    The holy grail in terms of flat panel displays has been an inexpensive process for the production of large area 'hang on the wall' television that is based on an emissive technology. Electron field emission displays, in principle, should be able to give high quality pictures with good colour saturation, and, if suitable technologies for the production of cathodes over large areas were to be made available, at low cost. This requires a process technology where temperatures must be maintained below 450/spl deg/C throughout the entire production cycle to be consistent with the softening temperature of display glass. In this paper we propose three possible routes for nanoscale engineering of large area cathodes using low temperature processing that can be integrated into a display technology. The first process is based on carbon nanotube-polymer composites that can be screen printed over large areas and show electron field emission properties comparable with some of the best aligned nanotube arrays. The second process is based on the large area growth of carbon nanofibres directly onto substrates held at temperatures ranging from room temperature to 300/spl deg/C, thereby making it possible to use inexpensive substrates. The third process is based on the use of excimer laser processing of amorphous silicon for the production of lithography-free large area three terminal nanocrystalline silicon substrates. Each route has its own advantages and flexibility in terms of incorporation into an existing display technology. The harnessing of these synergies will be highlighted together with the properties of the cathodes developed for the differing technologies.

    V Panchal, D Cox, R Yakimova, O Kazakova (2013)Epitaxial Graphene Sensors for Detection of Small Magnetic Moments, In: IEEE TRANSACTIONS ON MAGNETICS49(1)pp. 97-100
    Bo Li, T Godfrey, David Cox, T Li, J Gallop, Sebastian Galer, Andrew Nisbet, E Romans, L Hao (2018)Investigation of properties of nanobridge Josephson junctions and superconducting tracks fabricated by FIB, In: Journal of Physics: Conference Series - proceedings of the Advances in Quantum Transport in Low Dimensional Systems conference, 4–5 September 2017, London, UK964(Conf.1)012004pp. 1-6 Institute of Physics

    An important requirement across a range of sensitive detectors is to determine accurately the energy deposited by the impact of a particle in a small volume. The particle may be anything from a visible photon through to an X-ray or massive charged particle. We have been developing nanobridge Josephson junctions based SQUIDs and nanoSQUID devices covering the entire range of particle detection energies from 1eV to MeV. In this paper we discuss some developments in nanobridge Josephson junctions fabrication using focussed ion beam (FIB) and how these developments impact future applications. We focus on tuning of the transition temperature of a superconducting thin-film absorber, with the aim to match the absorber Tc to the working temperature range of the SQUID and also on using a new Xe FIB to improve Josephson junction and superconducting film quality.

    L Hao, JC Gallop, D Cox, EJ Romans, JC Macfarlane, J Chen (2009)Focused Ion Beam NanoSQUIDs as Novel NEMS Resonator Readouts, In: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY19(3)pp. 693-696
    F Renna, D Cox, G Brambilla (2009)Efficient sub-wavelength light confinement using surface plasmon polaritons in tapered fibers, In: OPT EXPRESS17(9)pp. 7658-7663 OPTICAL SOC AMER

    Light confinement to sub-wavelength spot sizes is proposed and realized in tapered optical fibers. To achieve high transmission efficiencies, light propagating along the taper is combined with the excitation of surface plasmon polaritons (SPP) at its tip. (C) 2009 Optical Society of America

    R. C. Smith, JD Carey, C. H. P. Poa, D. C. Cox, S. R. P. Silva (2004)Electron field emission from room temperature grown carbon nanofibers, In: Journal of Applied Physics95pp. 3153-3157

    The observation of field induced electron emission from room temperature grown carbon nanofibers at low (5 V/µm) macroscopic electric fields is reported. The nanofibers were deposited using methane as a source gas in a conventional rf plasma enhanced chemical vapor deposition reactor using a Ni metal catalyst previously subjected to an Ar plasma treatment. Analysis of the scanning electron microscopy images of the nanofibers show them to possess an average diameter of 300 nm and that the nanofibers are observed to be radially dispersed over an area of 50 µm in diameter. No evidence of hysteresis in the current-voltage characteristic or conditioning of the emitters is observed. The mechanism for emission at low fields is attributed to field enhancement at the tips rather than from the surrounding amorphous carbon film which is shown to have a higher threshold field (20 V/µm) for emission.

    GZ Mashanovich, MM Milosevic, M Nedeljkovic, D Cox, VMN Passaro, HMH Chong, R Soref (2012)Mid-infrared silicon photonics for sensing applications, In: Materials Research Society Symposium Proceedings1437pp. 7-16

    The mid-infrared wavelength region offers a plethora of possible applications ranging from sensing, medical diagnostics and free space communications, to thermal imaging and IR countermeasures. Hence group IV mid-infrared photonics is attracting more research interest lately. Sensing is an especially attractive area as fundamental vibrations of many important gases are found in the 3 to 14 μm spectral region. To realise group IV photonic mid-infrared sensors several serious challenges need to be overcome. The first challenge is to find suitable material platforms for the mid-infrared. In this paper we present experimental results for passive mid-infrared photonic devices realised in silicon-on-insulator (SOI), silicon-on-sapphire (SOS), and silicon on porous silicon (SiPSi). Although silicon dioxide is lossy in most parts of the mid-infrared, we have shown that it has potential to be used in the 3-4 μm region. We have characterized SOI waveguides with < 1 dB/cm propagation loss. We have also designed and fabricated SOI passive devices such as MMIs and ring resonators. For longer wavelengths SOS or SiPSi structures could be used. An important active device for long wavelength group IV photonics will be an optical modulator. We present relationships for the free-carrier induced electro-refraction and electro-absorption in silicon in the mid-infrared wavelength range. Electro-absorption modulation is calculated from impurity-doping spectra taken from the literature, and a Kramers-Kronig analysis of these spectra is used to predict electro-refraction modulation. We have examined the wavelength dependence of electro-refraction and electro-absorption, and found that the predictions suggest longer-wave modulator designs will in many cases be different than those used in the telecom range. © 2012 Materials Research Society.

    DA Zeze, DC Cox, BL Weiss, SRP Silva (2004)Lithography-free high aspect ratio submicron quartz columns by reactive ion etching, In: APPLIED PHYSICS LETTERS84(8)pp. 1362-1364 AMER INST PHYSICS
    H Shiozawa, A Bachmatiuk, A Stangl, DC Cox, SRP Silva, MH Ruemmeli, T Pichler (2013)Microscopic insight into the bilateral formation of carbon spirals from a symmetric iron core, In: SCIENTIFIC REPORTS3ARTN 1pp. ?-? NATURE PUBLISHING GROUP

    Mirrored carbon-spirals have been produced from pressured ferrocene via the bilateral extrusion of the spiral pairs from an iron core. A parametric plot of the surface geometry displays the fractal growth of the conical helix made with the logarithmic spiral. Electron microscopy studies show the core is a crystalline cementite which grows and transforms its shape from spherical to biconical as it extrudes two spiralling carbon arms. In a cross section along the arms we observe graphitic flakes arranged in a herringbone structure, normal to which defects propagate. Local-wave-pattern analysis reveals nanoscale defect patterns of two-fold symmetry around the core. The data suggest that the bilateral growth originates from a globular cementite crystal with molten surfaces and the nano-defects shape emerging hexagonal carbon into a fractal structure. Understanding and knowledge obtained provide a basis for the controlled production of advanced carbon materials with designed geometries.

    S Rozhko, T Hino, A Blois, L Hao, JC Gallop, DC Cox, EJ Romans (2013)Study of Low-Frequency Noise Performance of Nanobridge-Based SQUIDs in External Magnetic Fields, In: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY23(3)ARTN 16010 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    L Hao, DC Cox, JC Gallop, J Chen, S Rozhko, A Blois, EJ Romans (2013)Coupled NanoSQUIDs and Nano-Electromechanical Systems (NEMS) Resonators, In: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY23(3)ARTN 18003 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    DC Cox, RD Forrest, PR Smith, SRP Silva (2004)Thermionic emission from defective carbon nanotubes, In: APPLIED PHYSICS LETTERS85(11)pp. 2065-2067 AMER INST PHYSICS
    RK Rajkumar, DC Cox, A Tzalenchuk, O Kazakova, SRP Silva, A Manzin (2013)3-D mapping of sensitivity of graphene hall devices to local magnetic and electrical fields, In: IEEE Transactions on Magnetics49(7)pp. 3445-3448

    We report the response of sub-micron epitaxial graphene Hall devices to localized and inhomogeneous magnetic field produced by an MFM tip. We analyze the magneto-transport properties of epitaxial graphene and report the independent contribution of magnetic and electric fields in the measured transverse voltage maps with respect to the lateral and vertical position of the tip. A finite element model has also been developed to support the experimental results. © 2013 IEEE.

    DC Cox, RD Forrest, PR Smith, V Stolojan, SRP Silva (2005)Study of the current stressing in nanomanipulated three-dimensional carbon nanotube structures, In: APPLIED PHYSICS LETTERS87(3)ARTN 0pp. ?-? AMER INST PHYSICS
    SRP Silva, JD Carey, GY Chen, DC Cox, RD Forrest, CHP Poa, RC Smith, YF Tang, JM Shannon (2004)Nanoengineering of materials for field emission display technologies, In: IEE PROCEEDINGS-CIRCUITS DEVICES AND SYSTEMS151(5)pp. 489-496 IEE-INST ELEC ENG
    DC Cox, RD Forrest, PR Smith, SRP Silva (2004)Bespoke carbon nanotube devices and structures, In: NANOENGINEERED NANOFIBROUS MATERIALS169pp. 323-328
    L Di Michele, C Shelly, P de Marco, P See, D Cox, O Kazakova (2011)Detection and susceptibility measurements of a single Dynal bead, In: JOURNAL OF APPLIED PHYSICS110(6)ARTN 0pp. ?-? AMER INST PHYSICS
    CH Poa, RG Lacerda, DC Cox, SRP Silva, FC Marques (2002)Stress-induced electron emission from nanocomposite amorphous carbon thin films, In: APPLIED PHYSICS LETTERS81(5)pp. 853-855 AMER INST PHYSICS
    M Palumbo, SJ Henley, T Lutz, V Stolojan, D Cox, SRP Silva (2008)Engineering the shape of zinc oxide crystals via sonochemical or hydrothermal solution-based methods, In: Materials Research Society Proceedings1087pp. 59-65

    Recent results in the use of Zinc Oxide (ZnO) nano/submicron crystals in fields as diverse as sensors, UV lasers, solar cells, piezoelectric nanogenerators and light emitting devices have reinvigorated the interest of the scientific community in this material. To fully exploit the wide range of properties offered by ZnO, a good understanding of the crystal growth mechanism and related defects chemistry is necessary. However, a full picture of the interrelation between defects, processing and properties has not yet been completed, especially for the ZnO nanostructures that are now being synthesized. Furthermore, achieving good control in the shape of the crystal is also a very desirable feature based on the strong correlation there is between shape and properties in nanoscale materials. In this paper, the synthesis of ZnO nanostructures via two alternative aqueous solution methods - sonochemical and hydrothermal - will be presented, together with the influence that the addition of citric anions or variations in the concentration of the initial reactants have on the ZnO crystals shape. Foreseen applications might be in the field of sensors, transparent conductors and large area electronics possibly via ink-jet printing techniques or self-assembly methods.

    EJ Romans, S Rozhko, L Young, A Blois, L Hao, D Cox, JC Gallop (2011)Noise Performance of Niobium Nano-SQUIDs in Applied Magnetic Fields, In: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY21(3)pp. 404-407 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    Jonathan England, Patrick M. Martin, David Cox (2015)Techniques for generating three dimensional structures

    Techniques for forming a three dimensional (3D) feature on a substrate are disclosed. In one exemplary embodiment, the technique may be realized as a method comprising: forming a resist structure on the substrate, the resist structure having a first resist portion with a first thickness, a second resist portion with a second thickness, and a third resist portion with a third thickness, where the first thickness may be less than the second thickness, and where the second thickness may be less than the third thickness; implanting charged particles into the substrate through the first and second resist portions and forming an implanted region in the substrate; and etching the substrate to form the 3D feature on the substrate.

    Jonathan England, David Cox, Nathan Cassidy, Bobur Mirkhaydarov, Andres Perez-Fadon (2019)Investigating the formation of isotopically pure layers for quantum computers using ion implantation and layer exchange, In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms461pp. 30-36 Elsevier

    Quantum computers have been proposed that exploit entangled quantum states between atoms that are isolated from environmental perturbations in a “semiconductor vacuum” which can be formed by cryogenically cooling an isotopically pure, defect free crystalline layer consisting of Si, or Ge. In a preliminary investigation of an implant and deposition layer exchange technique to produce such “vacuums”, a layer of aluminium was implanted with 28Si using a conventional implanter. After annealing and cross sectioning, layer exchange was observed to have produced multiple isolated crystals in a cross sectional TEM image. Further deposited Al layers were implanted with Ge using a SIMPLE (Single Ion Multispecies Positioning at Low Energy) implanter over a range of fluences. After anneals at 250 °C and Al removal, crystals of Ge (which also contained Si) were seen at areal densities that increased with implant fluence.

    E Brown, L Hao, DC Cox, JC Gallop, LSO Johansson, JN Andersen, M Gothelid, U Helmersson, L Montelius, M Rubel, J Setina, LE Wernersson (2008)Scanning thermal microscopy probe capable of simultaneous electrical imaging and the addition of a diamond tip, In: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY100pp. ?-?
    L Hao, D Cox, P See, J Gallop, O Kazakova (2010)Magnetic nanoparticle detection using nano-SQUID sensors, In: JOURNAL OF PHYSICS D-APPLIED PHYSICS43(47)ARTN 47400 IOP PUBLISHING LTD
    KK Devarepally, David Cox, AT Fry, Vlad Stolojan, Richard Curry, M Munz (2011)Synthesis of linear ZnO structures by a thermal decomposition method and their characterisation, In: Journal of Materials Science47(4)pp. 1893-1901 Springer

    The semiconductor zinc oxide (ZnO) is a promising material for applications in optoelectronics, photochemistry and chemical sensing. Furthermore, ZnO structures can be grown with a large variety of sizes and shapes. Devices with ZnO rods or wires as their core elements can be used in solar cells, gas sensors or biosensors. In this article, an easy approach for the non-aqueous wet chemical synthesis of ZnO structures is presented that employs the solvent trioctylamine (TOA) and the surfactant hexamethylenetetramine (HMTA). Using the thermal decomposition method, rod-shaped structures were grown that are suitable for the fabrication of electrical devices. A detailed study was carried out to investigate the effects of various reaction parameters on the growth process. Both the concentration of the surfactant HMTA and the zinc precursor zincacetylacetonate (Zn(acac)2) were found to show strong effects on the resulting morphology. In addition to structural characterisation using XRD, SEM and TEM, also optical properties of rod-shaped ZnO structures were measured. Rod-shaped structures were obtained for the following conditions: reaction time 4 h, reaction temperature 70 °C, 1 mmol of Zn(acac)2, 4 mmol of HMTA and 25 mL of the solvent TOA. Photoluminescence and photoluminescence excitation spectroscopy of samples grown under these conditions provided information on levels of defect states that could be critical for chemical sensing applications. Two narrow peaks around 254 and 264 nm were found that are well above the band gap of ZnO.

    L Hao, C Assmann, JC Gallop, D Cox, F Ruede, O Kazakova, P Josephs-Franks, D Drung, T Schurig (2011)Detection of single magnetic nanobead with a nano-superconducting quantum interference device, In: APPLIED PHYSICS LETTERS98(9)ARTN 0pp. ?-? AMER INST PHYSICS
    L Hao, JC Gallop, D Cox (2009)Excitation, detection, and passive cooling of a micromechanical cantilever using near-field of a microwave resonator, In: APPLIED PHYSICS LETTERS95(11)ARTN 1pp. ?-? AMER INST PHYSICS
    I Rod, O Kazakova, DC Cox, M Spasova, M Farle (2009)The route to single magnetic particle detection: a carbon nanotube decorated with a finite number of nanocubes, In: NANOTECHNOLOGY20(33)ARTN 33530 IOP PUBLISHING LTD
    E Borowiak-Palen, MH Ruemmeli, E Mendoza, SJ Henley, DC Cox, CHP Poa, V Stolojan, T Gemming, T Pichler, SRP Silva (2005)Silver intercalated carbon nanotubes, In: Electronic Properties of Novel Nanostructures786pp. 236-239 AMER INST PHYSICS
    F Renna, G Brambilla, DC Cox (2009)Light Confinement in Optical Fibers Using Surface Plasmon Polaritons, In: IEEE PHOTONICS TECHNOLOGY LETTERS21(20)pp. 1508-1510 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    H Corte-Leon, P Krzysteczko, HW Schumacher, A Manzin, D Cox, V Antonov, O Kazakova (2015)Magnetic bead detection using domain wall-based nanosensor, In: JOURNAL OF APPLIED PHYSICS117(17)ARTN 17E31 AMER INST PHYSICS
    I Rod, C Wirtz, O Kazakova, V Panchal, D Cox, H Zähres, O Posth, J Lindner, R Meckenstock, M Farle (2012)Carbon nanotube bolometer: Transport properties and noise characteristics, In: Solid State Phenomena190pp. 510-513

    The temperature dependent resistance and the noise characteristics of an individual multiwall carbon nanotube (CNT) decorated with a finite number of magnetic nanocubes are investigated. We show that CNT is a highly sensitive bolometer and can enable measurements of magnetic resonance in a single nanoparticle. © (2012) Trans Tech Publications.

    L Hao, JC Macfarlane, JC Gallop, D Cox, P Joseph-Franks, D Hutson, J Chen, SKH Lam (2007)Novel methods of fabrication and metrology of superconducting nanostructures, In: IEEE Transactions on Instrumentation and Measurement56(2)pp. 392-396

    As metrology extends toward the nanoscale, a number of potential applications and new challenges arise. By combining photolithography with focused ion beam and/or electron beam methods, superconducting quantum interference devices (SQUIDs) with loop dimensions down to 200 nm and superconducting bridge dimensions of the order 80 nm have been produced. These SQUIDs have a range of potential applications. As an illustration, we describe a method for characterizing the effective area and the magnetic penetration depth of a structured superconducting thin film in the extreme limit, where the superconducting penetration depth λ is much greater than the film thickness and is comparable with the lateral dimensions of the device. © 2007 IEEE.

    RC Smith, WM Tsang, DC Cox, SRP Silva (2005)Electron field emission from a single carbon nanotube: Effects of anode location, In: Technical Digest of the 18th International Vacuum Nanoelectronics Conference, IVNC 20052005pp. 264-265
    L Hao, DC Cox, JC Gallop (2009)Characteristics of focused ion beam nanoscale Josephson devices, In: SUPERCONDUCTOR SCIENCE & TECHNOLOGY22(6)ARTN 06401 IOP PUBLISHING LTD
    L Hao, D Cox, K Lees, JC Gallop, P See, R Clarke, TJBM Janssen, RF Zhang, F Wei (2012)Fabrication and Characterization of Carbon Nanotubes as r.f. Interconnects, In: 2012 12TH IEEE CONFERENCE ON NANOTECHNOLOGY (IEEE-NANO)
    PF Griffin, J Harris, G Mcconnell, AS Arnold, D Cox, E Riis (2009)Investigation of micrometre scale parabolic mirrors for use as single atom quantum registers, In: CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference
    CHP Poa, RG Lacerda, DC Cox, FC Marques, SRP Silva (2003)Effects of stress on electron emission from nanostructured carbon materials, In: JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B21(4)pp. 1710-1714
    O Kazakova, V Panchal, J Gallop, P See, DC Cox, M Spasova, LF Cohen (2010)Ultrasmall particle detection using a submicron Hall sensor, In: JOURNAL OF APPLIED PHYSICS107(9)pp. ?-?
    T Patel, B Li, J Gallop, D Cox, K Kirkby, E Romans, J Chen, A Nisbet, L Hao (2015)Investigating the intrinsic noise limit of Dayem bridge NanoSQUIDs, In: IEEE Transactions on Applied Superconductivity25(3)

    © 2014 IEEE.NanoSQUIDs made from Nb thin films have been produced with nanometre loop sizes down to 200 nm, using weak-link junctions with dimensions less than 60 nm. These composite (W/Nb) single layer thin film devices, patterned by FIB milling, show extremely good low-noise performance ~170 nΦ0 at temperatures between 5 and 8.5 K and can operate in rather high magnetic fields (at least up to 1 T). The devices produced so far have a limited operating temperature range, typically only 1-2 K. We have the goal of achieving operation at 4.2 K, to be compatible with the best SQUID series array (SSA) preamplifier available. Using the SSA to readout the nanoSQUIDs provides us with a means of investigating the intrinsic noise of the former. In this paper we report improved white noise levels of these nanoSQUIDs, enabling potential detection of a single electronic spin flip in a 1-Hz bandwidth. At low frequencies the noise performance is already limited by SSA preamplifier noise.

    RC Smith, DC Cox, SRP Silva (2008)In situ field emission characterization of multiwalled carbon nanotubes, In: JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B26(2)pp. 842-846
    RD Forrest, DC Cox, YF Tang, JM Shannon, SRP Silva (2003)Fabrication of a self-aligned microtip field emission array, In: JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B21(4)pp. 1560-1565
    V Tison, V Stolojan, PCP Watts, DC Cox, GY Chen, SRP Silva (2008)Gas Sensing Properties of Vapour-Deposited Tungsten Oxide Nanostructures, In: MICROSCOPY OF SEMICONDUCTING MATERIALS 2007120pp. 281-284
    DC Cox, V Stolojan, G Chen, SR Silva, AG Cullis, PA Midgley (2008)In situ Observation of the Growth of Tungsten Oxide Nanostructures, In: MICROSCOPY OF SEMICONDUCTING MATERIALS 2007120pp. 277-280
    DA Zeze, RD Forrest, JD Carey, DC Cox, ID Robertson, BL Weiss, SRP Silva (2002)Reactive ion etching of quartz and Pyrex for microelectronic applications, In: JOURNAL OF APPLIED PHYSICS92(7)pp. 3624-3629 AMER INST PHYSICS

    "The reactive ion etching of quartz and Pyrex substrates was carried out using CF4/Ar and CF4/O2 gas mixtures in a combined radio frequency (rf)/microwave (µw) plasma. It was observed that the etch rate and the surface morphology of the etched regions depended on the gas mixture (CF4/Ar or CF4/O2), the relative concentration of CF4 in the gas mixture, the rf power (and the associated self-induced bias) and microwave power. An etch rate of 95 nm/min for quartz was achieved. For samples covered with a thin metal layer, ex situ high resolution scanning electron microscopy and atomic force microscopy imaging indicated that, during etching, surface roughness is produced on the surface beneath the thin metallic mask. Near vertical sidewalls with a taper angle greater than 80° and smooth etched surfaces at the nanometric scale were fabricated by carefully controlling the etching parameters and the masking technique. A simulation of the electrostatic field distribution was carried out to understand the etching process using these masks for the fabrication of high definition features.

    FC Marques, RG Lacerda, A Champi, V Stolojan, DC Cox, SRP Silva (2003)Thermal expansion coefficient of hydrogenated amorphous carbon, In: APPLIED PHYSICS LETTERS83(15)pp. 3099-3101 AMER INST PHYSICS
    L Hao, JC Macfarlane, JC Gallop, D Cox, J Beyer, D Drung, T Schurig (2008)Measurement and noise performance of nano-superconducting-quantum-interference devices fabricated by focused ion beam, In: APPLIED PHYSICS LETTERS92(19)ARTN 1pp. ?-? AMER INST PHYSICS
    M Palumbo, T Lutz, CE Giusca, H Shiozawa, V Stolojan, DC Cox, RM Wilson, SJ Henley, SRP Silva (2009)From Stems (and Stars) to Roses: Shape-Controlled Synthesis of Zinc Oxide Crystals, In: CRYSTAL GROWTH & DESIGN9(8)pp. 3432-3437 AMER CHEMICAL SOC
    B. N Murdin, Nathan Cassidy, David Cox, Roger Webb, Richard J Curry (2021)Error Rates in Deterministic Ion Implantation for Qubit Arrays, In: physica status solidi (b)2000615 Wiley

    The theoretical error rates in deterministic ion implantation when using an ion beam governed by a Poisson point process with a detector that counts the impacts are investigated. It is concluded that if the error rates are small, then for spots with nominally one implanted ion the probability of failure to implant the correct number is ≈ 𝜅/𝜆+𝜂⎯⎯+𝜆/2 for a synchronous (i.e., pulsed) system or 𝐾/𝐿+𝜂⎯⎯+𝐿𝑡s for an asynchronous (i.e., continuous beam) system, where 𝜂⎯⎯ is the probability that the detector misses an ion impact, and 𝐿(𝐾) and 𝜆(𝜅) are the number of ions (dark counts) per unit time and per pulse, respectively. ts is the system reaction time for an asynchronous system. This approximation allows easy identification of the greatest need for engineering effort. Some experimental efforts to measure these parameters and their uncertainties are examined.

    RC Smith, JD Carey, DC Cox, SRP Silva (2006)In situ electrode manipulation for three terminal field emission characterization of individual carbon nanotubes, In: APPLIED PHYSICS LETTERS89(6)ARTN 0pp. ?-? AMER INST PHYSICS

    In situ three terminal electron field emission characterization of an isolated multiwalled carbon nanotube has been performed, where both anode and gate electrodes are attached to high precision piezodrivers. All measurements are performed in a scanning electron microscope allowing accurate knowledge of the local environment of the nanotube to be obtained. It is shown that the presence of the grounded gate electrode screens the applied field by approximately 32%. This technique in positioning the gate and anode electrodes allows for an estimate of the gate transparency factor and demonstrates characterization of individual carbon nanotubes without the need for fabrication of arrays of emitters.

    Y Miyajima, JM Shannon, SJ Henley, V Stolejan, DC Cox, SRP Silva (2007)Electrical conduction mechanism in laser deposited amorphous carbon, In: THIN SOLID FILMS516(2-4)pp. 257-261
    AJ Wain, D Cox, S Zhou, A Turnbull (2011)High-aspect ratio needle probes for combined scanning electrochemical microscopy-Atomic force microscopy, In: ELECTROCHEMISTRY COMMUNICATIONS13(1)pp. 78-81 ELSEVIER SCIENCE INC
    GL Kerr, DC Cox, V Stolojan, SRP Silva, RT Baker, G Mobus, PD Brown (2008)Characterisation of electron-beam deposited tungsten interconnects, In: EMAG: ELECTRON MICROSCOPY AND ANALYSIS GROUP CONFERENCE 2007126pp. ?-?
    MM Milošević, DJ Thomson, X Chen, D Cox, GZ Mashanovich (2011)Silicon waveguides for the 3-4 μm wavelength range, In: 8th IEEE International Conference on Group IV Photonicspp. 208-210

    In this paper we report propagation and bend loss measurements for silicon-on-insulator (SOI) and silicon-on-sapphire (SOS) waveguides at 3.39 μm wavelength. Preliminary experimental results for SOI rib waveguides at around 3.8 μm are also given.

    GT Reed, DJ Thomson, FY Gardes, Y Hu, N Owens, X Yang, P Petropoulos, K Debnath, L O'Faolain, TF Krauss, L Lever, Z Ikonic, RW Kelsall, M Myronov, DR Leadley, IP Marko, SJ Sweeney, DC Cox, A Brimont, P Sanchis, G-H Duan, A Le Liepvre, C Jany, M Lamponi, D Make, F Lelarge, JM Fedeli, S Messaoudene, S Keyvaninia, G Roelkens, D Van Thourhout, S Liu (2012)High performance silicon optical modulators, In: Proceedings of SPIE - The International Society for Optical Engineering8564

    In this work we present results from high performance silicon optical modulators produced within the two largest silicon photonics projects in Europe; UK Silicon Photonics (UKSP) and HELIOS. Two conventional MZI based optical modulators featuring novel self-aligned fabrication processes are presented. The first is based in 400nm overlayer SOI and demonstrates 40Gbit/s modulation with the same extinction ratio for both TE and TM polarisations, which relaxes coupling requirements to the device. The second design is based in 220nm SOI and demonstrates 40Gbits/s modulation with a 10dB extinction ratio as well modulation at 50Gbit/s for the first time. A ring resonator based optical modulator, featuring FIB error correction is presented. 40Gbit/s, 32fJ/bit operation is also shown from this device which has a 6um radius. Further to this slow light enhancement of the modulation effect is demonstrated through the use of both convention photonic crystal structures and corrugated waveguides. Fabricated conventional photonic crystal modulators have shown an enhancement factor of 8 over the fast light case. The corrugated waveguide device shows modulation efficiency down to 0.45V.cm compared to 2.2V.cm in the fast light case. 40Gbit/s modulation is demonstrated with a 3dB modulation depth from this device. Novel photonic crystal based cavity modulators are also demonstrated which offer the potential for low fibre to fibre loss. In this case preliminary modulation results at 1Gbit/s are demonstrated. Ge/SiGe Stark effect devices operating at 1300nm are presented. Finally an integrated transmitter featuring a III-V source and MZI modulator operating at 10Gbit/s is presented. © 2012 SPIE.

    RC Smith, JD Carey, CHP Poa, DC Cox, SRP Silva (2004)Electron field emission from room temperature grown carbon nanofibers, In: JOURNAL OF APPLIED PHYSICS95(6)pp. 3153-3157 AMER INST PHYSICS
    DJ Thomson, FY Gardes, DC Cox, J-M Fedeli, GZ Mashanovich, GT Reed (2013)Self-aligned silicon ring resonator optical modulator with focused ion beam error correction, In: JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS30(2)pp. 445-449 OPTICAL SOC AMER
    DJ Thomson, FY Gardes, DC Cox, JM Fedeli, GZ Mashanovich, GT Reed (2012)An alignment tolerant high speed ring resonator based silicon optical modulator, In: IEEE International Conference on Group IV Photonics GFPpp. 198-200

    Optical modulation up to 40Gbit/s from a silicon ring resonator based device is demonstrated. A self-aligned process is used to form the pn junction reducing performance variations. The power consumption of the device is 8fJ/bit. © 2012 IEEE.

    L Hao, JC Macfarlane, JC Gallop, E Romans, D Cox, D Hutson, J Chen (2007)Spatial resolution assessment of Nano-SQUIDs made by focused ion beam, In: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY17(2)pp. 742-745
    S Bechstein, F Ruede, D Drung, J-H Storm, C Koehn, OF Kieler, J Kohlmann, T Weimann, T Patel, B Li, D Cox, JC Gallop, L Hao, T Schurig (2015)Design and Fabrication of Coupled NanoSQUIDs and NEMS, In: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY25(3)ARTN 16026 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    A Suutala, J Olkkonen, DC Cox, J Lappalainen, H Jantunen (2009)Inverted method for fabricating a nano-aperture device with subwavelength structures, In: JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B27(6)pp. 2457-2461 A V S AMER INST PHYSICS
    L Gomez-Rojas, S Bhattacharyya, E Mendoza, DC Cox, JM Rosolen, SRP Silva (2007)RF response of single-walled carbon nanotubes, In: NANO LETTERS7(9)pp. 2672-2675 AMER CHEMICAL SOC
    M Munz, DC Cox, PJ Cumpson (2008)Nano-scale shear mode testing of the adhesion of nanoparticles to a surface-support, In: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE205(6)pp. 1424-1428
    GY Chen, Vlad Stolojan, David Cox, C Giusca, S Silva (2006)Growth of tungsten oxide nanowires using simple thermal heating, In: 2006 IEEE Conference on Emerging Technologies - Nanoelectronicspp. 376-378

    Tungsten oxide nanowires are grown directly on tungsten wires and plates using thermal heating in an acetylene and nitrogen mixture. By heating the tungsten in nitrogen ambient, single crystal tungsten oxide nanowires can be synthesized via a self-assembly mechanism. It was found that the yield can be significantly increased with the addition of acetylene, which also results in thinner nanowires, as compared to nanowires synthesized in an oxidizing ambient. The tungsten oxide nanowires are 5 to 15 nm in diameter and hundreds of nanometers in length. In some cases, the use of acetylene and nitrogen process gas would result in tungsten oxide nanowires samples that appear visually,transparent. Comparison of the growth using the acetylene/nitrogen or then air/nitrogen mixtures is carried out. A possible synthesis mechanism, taking into account the effect of hydrocarbon addition is proposed.

    HJ Burch, E Brown, SA Contera, NC Toledo, DC Cox, N Grobert, L Hao, JF Ryan, JA Davies (2008)Effect of acid treatment on the structure and electrical properties of nitrogen-doped multiwalled carbon nanotubes, In: JOURNAL OF PHYSICAL CHEMISTRY C112(6)pp. 1908-1912 AMER CHEMICAL SOC
    S Howe, WR Headley, DC Cox, GZ Mashanovich, DJ Thomson, GT Reed (2009)Fabrication and tailoring of silicon photonic devices via focused Ion, In: Proceedings of SPIE - The International Society for Optical Engineering7220
    L Hao, JC Gallop, DC Cox, J Chen (2015)Fabrication and Analogue Applications of NanoSQUIDs Using Dayem Bridge Junctions, In: IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS21(2)ARTN 91001pp. 1-8 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    O Kazakova, JC Gallop, P See, D Cox, GK Perkins, JD Moore, LF Cohen (2009)Detection of a Micron-Sized Magnetic Particle Using InSb Hall Sensor, In: IEEE TRANSACTIONS ON MAGNETICS45(10)pp. 4499-4502
    DA Zeze, RD Forrest, JD Carey, DC Cox, ID Robertson, BL Weiss, SRP Silva (2002)Reactive ion etching of quartz and Pyrex for microelectronic applications, In: JOURNAL OF APPLIED PHYSICS92(7)pp. 3624-3629 AMER INST PHYSICS

    The reactive ion etching of quartz and Pyrex substrates was carried out using CF /Ar and CF /O gas mixtures in a combined radio frequency (rf)/microwave (μw) plasma. It was observed that the etch rate and the surface morphology of the etched regions depended on the gas mixture (CF /Ar or CF /O ), the relative concentration of CF in the gas mixture, the rf power (and the associated self-induced bias) and microwave power. An etch rate of 95 nm/min for quartz was achieved. For samples covered with a thin metal layer, ex situ high resolution scanning electron microscopy and atomic force microscopy imaging indicated that, during etching, surface roughness is produced on the surface beneath the thin metallic mask. Near vertical sidewalls with a taper angle greater than 80° and smooth etched surfaces at the nanometric scale were fabricated by carefully controlling the etching parameters and the masking technique. A simulation of the electrostatic field distribution was carried out to understand the etching process using these masks for the fabrication of high definition features. © 2002 American Institute of Physics.

    PR Smith, JD Carey, DC Cox, RD Forrest, SRP Silva (2009)On the importance of the electrostatic environment for the transport properties of freestanding multiwall carbon nanotubes, In: NANOTECHNOLOGY20(14)ARTN 1pp. ?-? IOP PUBLISHING LTD

    Electrical measurements of freestanding multiwall carbon nanotubes using high resistance tunnelling contacts reveal a power law behaviour,I∝V^(α+1), with α as high as 5.2, followed by a transition to an offset ohmic behaviour. The freestanding electrode geometry allows for a distinction between the predictions from Luttinger liquid and environmental quantum fluctuation (EQF) theories to be made. The high values of exponents found are explained within the EQF formulism, where reflections resulting from the impedance discontinuity caused by the freestanding geometry are included.

    Vasileios Katranidis, Sai Gu, David Cox, Mark J Whiting, Spyros Kamnis (2018)FIB-SEM Sectioning Study of Decarburization Products in the Microstructure of HVOF-Sprayed WC-Co Coatings, In: Journal of Thermal Spray Technology27(5)pp. 898-908 Springer

    The thermal dissolution and decarburization of WC-based powders that occur in various spray processes are a widely studied phenomenon, and mechanisms that describe its development have been proposed. However, the exact formation mechanism of decarburization products such as metallic W is not yet established. A WC-17Co coating is sprayed intentionally at an exceedingly long spray distance to exaggerate the decarburization effects. Progressive xenon plasma ion milling of the examined surface has revealed microstructural features that would have been smeared away by conventional polishing. Serial sectioning provided insights on the three-dimensional structure of the decarburization products. Metallic W has been found to form a shell around small splats that did not deform significantly upon impact, suggesting that its crystallization occurs during the in-flight stage of the particles. W2C crystals are more prominent on WC faces that are in close proximity with splat boundaries indicating an accelerated decarburization in such sites. Porosity can be clearly categorized in imperfect intersplat contact and oxidation-generated gases via its shape.

    J Gallop, D Cox, L Hao (2015)Nanobridge SQUIDs as calorimetric inductive particle detectors, In: SUPERCONDUCTOR SCIENCE & TECHNOLOGY28(8)ARTN 08400 IOP PUBLISHING LTD
    E Koukharenko, X Li, I Nandhakumar, N Frety, SP Beeby, D Cox, MJ Tudor, B Schiedt, C Trautmann, A Bertsch, NM White (2008)Towards a nanostructured thermoelectric generator using ion-track lithography, In: JOURNAL OF MICROMECHANICS AND MICROENGINEERING18(10)
    H Shiozawa, Anne Skeldon, David Lloyd, V Stolojan, DC Cox, SR Silva (2011)Spontaneous emergence of long-range shape symmetry, In: Nano Letters11(1)pp. 160-163

    Self-organization of matter is essential for natural pattern formation, chemical synthesis, as well as modern material science. Here we show that isovolumetric reactions of a single organometallic precursor allow symmetry breaking events from iron nuclei to the creation of different symmetric carbon structures: microspheres, nanotubes, and mirrored spiraling microcones. A mathematical model, based on mass conservation and chemical composition, quantitatively explains the shape growth. The genesis of such could have significant implications for material design.

    RC Smith, JD Carey, DC Cox, SRP Silva (2006)In situ electrode manipulation for three terminal field emission characterization of individual carbon nanotubes, In: APPLIED PHYSICS LETTERS89(6)ARTN 0pp. ?-? AMER INST PHYSICS

    In situ three terminal electron field emission characterization of an isolated multiwalled carbon nanotube has been performed, where both anode and gate electrodes are attached to high precision piezodrivers. All measurements are performed in a scanning electron microscope allowing accurate knowledge of the local environment of the nanotube to be obtained. It is shown that the presence of the grounded gate electrode screens the applied field by approximately 32%. This technique in positioning the gate and anode electrodes allows for an estimate of the gate transparency factor and demonstrates characterization of individual carbon nanotubes without the need for fabrication of arrays of emitters.

    E Castaldelli, KDGI Jayawardena, David Cox, GJ Clarkson, RI Walton, L Le-Quang, J Chauvin, S Silva, GJ-F Demets (2017)Electrical semiconduction modulated by light in a cobalt and naphthalene diimide metal-organic framework, In: Nature Communications82139 Nature Publishing Group

    Metal-organic frameworks (MOFs) have emerged as an exciting class of porous materials that can be structurally designed by choosing particular components according to desired applications. De- spite the wide interest in and many potential applications of MOFs, such as in gas storage, catal- ysis, sensing and drug delivery, electrical semiconductivity and its control is still rare. The use and fabrication of electronic devices with MOF-based components has not been widely explored, despite the significant progress of these components made in recent years. Here we report the syn- thesis and properties of a new highly crystalline, electrochemically active, cobalt and naphthalene diimide-based MOF that is an efficient electrical semiconductor and has a broad absorption spec- trum, from 300 nm to 2500 nm. Its semiconductivity was determined by direct voltage bias using a four-point device, and it features a wavelength dependant photoconductive-photoresistive dual behaviour, with a very high responsivity of 2.5×105 A W−1.

    O Kazakova, JC Gallop, DC Cox, E Brown, A Cuenat, K Suzuki (2008)Optimization of 2DEG InAs/GaSb Hall Sensors for Single Particle Detection, In: IEEE TRANSACTIONS ON MAGNETICS44(11)pp. 4480-4483
    R C Smith, JD Carey, C H Poa, D C Cox, S R Silva (2004)Electron Field Emission From Room Temperature Grown Carbon Nanofibers, In: Journal of Applied Physics95(6)

    The observation of field induced electron emission from room temperature grown carbon nanofibers at low (5 V/mum) macroscopic electric fields is reported. The nanofibers were deposited using methane as a source gas in a conventional rf plasma enhanced chemical vapor deposition reactor using a Ni metal catalyst previously subjected to an Ar plasma treatment. Analysis of the scanning electron microscopy images of the nanofibers show them to possess an average diameter of 300 nm and that the nanofibers are observed to be radially dispersed over an area of 50 mum in diameter. No evidence of hysteresis in the current-voltage characteristic or conditioning of the emitters is observed. The mechanism for emission at low fields is attributed to field enhancement at the tips rather than from the surrounding amorphous carbon film which is shown to have a higher threshold field (20 V/mum) for emission.

    A McDonald, G McConnell, DC Cox, E Riis, PF Griffin (2015)3D mapping of intensity field about the focus of a micrometer-scale parabolic mirror, In: OPTICS EXPRESS23(3)pp. 2375-2382 OPTICAL SOC AMER
    Mateus G. Masteghin, Muhammad Ahmad, Mehmet Tas, Christopher Smith, Vlad Stolojan, David Cox, Ravi Silva (2020)Field electron emission measurements as a complementary technique to assess carbon nanotube quality, In: Applied physics letters116103101 American Institute of Physics

    Carbon nanotubes (CNTs) can be used in many different applications. Field emission (FE) measurements were used together with Raman spectroscopy to show a correlation between the microstructure and field emission parameters. However, field emission characterization does not suffer from fluorescence noise present in Raman spectroscopy. In this study, Raman spectroscopy is used to characterize vertically aligned CNT forest samples based on their D/G band intensity ratio (ID/IG), and FE properties such as the threshold electric field, enhancement coefficient, and anode to CNT tip separation (ATS) at the outset of emission have been obtained. A relationship between ATS at first emission and the enhancement factor, and, subsequently, a relationship between ATS and the ID/IG are shown. Based on the findings, it is shown that a higher enhancement factor (3070) results when a lower ID/IG is present (0.45), with initial emissions at larger distances (47 lm). For the samples studied, the morphology of the CNT tips did not play an important role; therefore, the field enhancement factor (b) could be directly related to the carbon nanotube structural properties such as breaks in the lattice or amorphous carbon content. Thus, this work presents FE as a complementary tool to evaluate the quality of CNT samples, with the advantages of alarger probe size and an averaging over the whole nanotube length. Correspondingly, one can find the best field emitter CNT according to its ID/IG.

    CH Webster, SP Giblin, D Cox, TJBM Janssen, AB Zorin (2008)A quantum current standard based on phase slip, In: 2008 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS DIGESTpp. 628-629
    L Hao, JC Macfarlane, JC Gallop, D Cox, P Joseph-Franks, D Hutson, R Chen, SKH Lam (2007)Novel methods of fabrication and metrology of superconducting nanostructures, In: IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT56(2)pp. 392-396
    N. Cassidy, P. Blenkinsopp, I. Dr. Brown, Prof. R. J Curry, Prof. B.N Murdin, Prof R.B Webb, Dr. D.C Cox (2020)Single Ion Implantation of Bismuth, In: Physica Status Solidi A: Applications and Materials Science Wiley

    We present the results from a focused ion beam instrument designed to implant single ions with a view to the fabrication of qubits for quantum technologies. The difficulty of single ion implantation is accurately counting the ion impacts. This has been achieved here through the detection of secondary electrons generated upon each ion impact. We report implantation of single bismuth ions with different charge states into Si, Ge, Cu and Au substrates, and we determine the counting detection efficiency for single ion im- plants and the factors which affect such detection efficiencies. We found that for 50 keV implants of Bi++ ions into silicon we can achieve a 89% detection efficiency, the first quantitative detection efficiency measurement for single ion implants into silicon without implanting through a thick SiO2 film. This level of counting accuracy provides implantation of single impurity ions with a success rate significantly exceeding that achievable by random (Poissonian) implantation.

    RG Lacerda, V Stolojan, DC Cox, SRP Silva, FC Marques (2002)Structural characterization of hard a-C : H films as a function of the methane pressure, In: DIAMOND AND RELATED MATERIALS11(3-6)pp. 980-984
    RC Smith, JD Carey, DC Cox, SRP Silva (2007)In-situ field emission characterisation of multi walled carbon nanotubes, In: Technical Digest of the 20th International Vacuum Nanoelectronics Conference, IVNC 07pp. 94-95
    S Bechstein, A Kirste, D Drung, M Regin, O Kazakova, J Gallop, L Hao, D Cox, T Schurig (2013)Investigation of Material Effects With Micro-Sized SQUID Sensors, In: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY23(3)ARTN 16020 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    T Goto, Y Harada, D Cox, K Sumitomo (2014)Fabrication of a ring structure at the aperture of a hole for the efficient suspension of a lipid bilayer, In: JAPANESE JOURNAL OF APPLIED PHYSICS53(9)ARTN 09650 IOP PUBLISHING LTD