36,282 research outputs found
Investigation of the shape transferability of nanoscale multi-tip diamond tools in the diamond turning of nanostructures
No full textIn this article, the shape transferability of using nanoscale multi-tip diamond tools in the diamond turning for scale-up manufacturing of nanostructures has been demonstrated. Atomistic multi-tip diamond tool models were built with different tool geometries in terms of the difference in the tip cross-sectional shape, tip angle, and the feature of tool tip configuration, to determine their effect on the applied forces and the machined nano-groove geometries. The quality of machined nanostructures was characterized by the thickness of the deformed layers and the dimensional accuracy achieved. Simulation results show that diamond turning using nanoscale multi-tip tools offers tremendous shape transferability in machining nanostructures. Both periodic and non-periodic nano-grooves with different cross-sectional shapes can be successfully fabricated using the multi-tip tools. A hypothesis of minimum designed ratio of tool tip distance to tip base width (L/Wf) of the nanoscale multi-tip diamond tool for the high precision machining of nanostructures was proposed based on the analytical study of the quality of the nanostructures fabricated using different types of the multi-tip tools. Nanometric cutting trials using nanoscale multi-tip diamond tools (different in L/Wf) fabricated by focused ion beam (FIB) were then conducted to verify the hypothesis. The investigations done in this work imply the potential of using the nanoscale multi-tip diamond tool for the deterministic fabrication of period and non-periodic nanostructures, which opens up the feasibility of using the process as a versatile manufacturing technique in nanotechnology
BridgING
No full textBridgING is an assemblage of work produced by students from the MA Interior, Architectural & Spatial Design programme at Edinburgh College of Art. This work has been developed through a year-long engagement with Edinburgh’s George IV Bridge, and produced a wide range of creative, critical and imaginative research outcomes and design responses. Through these activities, the student cohort has tested and probed the thresholds and definitions of the interior, to propose original projects that can shape and contribute to the stories of Edinburgh’s rich and vibrant urban context
Over 50 mA current in interdigitated diamond field effect transistor
No full textInternational audienceThis letter presents the bulk diamond field-effect transistor (FET) with the highest current value reported at this moment. The goal was to drastically increase the current of this type of device by increasing the total gate width thanks to an interdigitated architecture and homogeneous growth properties. We report the results obtained by fabricating and characterizing an interdigitated junction FET (JFET). The device develops a total gate width of 14.7 mm, with 24 paralleled fingers and a current higher than 50 mA at VDS = -15 V, VGS = 0 V, at 450 K and under illumination which is the highest value reported for a bulk diamond FET. Its specific ON-resistance and threshold voltage are respectively 608 mΩ.cm², 50 V. From Transfer length method (TLM) measurements we extract a resistivity of 3.6 mΩ.cm for a heavily boron-doped (p++)-diamond layer and 1.52 Ω.cm for a 2.1017 cm-3 p-doped diamond layer at 450 K. We measured the drain current versus gate voltage characteristics at high temperature showing that it is no longer the conduction channel resistance but the device access resistance that is predominant. This study indicates that it is possible to drastically improve the ON-state of FETs by using an interdigitated architecture, while using homogeneous large size diamond layers grown by CVD
Magnetometry with nitrogen-vacancy defects in diamond
No full textThe isolated electronic spin system of the nitrogen-vacancy (NV) centre in diamond offers unique possibilities to be employed as a nanoscale sensor for detection and imaging of weak magnetic fields. Magnetic imaging with nanometric resolution and field detection capabilities in the nanotesla range are enabled by the atomic-size and exceptionally long spin-coherence times of this naturally occurring defect. The exciting perspectives that ensue from these characteristics have triggered vivid experimental activities in the emerging field of ‘NV magnetometry’. It is the purpose of this article to review the recent progress in high-sensitivity nanoscale NV magnetometry, generate an overview of the most pertinent results of the last years and highlight perspectives for future developments. We will present the physical principles that allow for magnetic field detection with NV centres and discuss first applications of NV magnetometers that have been demonstrated in the context of nano magnetism, mesoscopic physics and the life sciences
Electron field emission properties on ultra-nano-crystalline diamond coated silicon nanowires
No full textUltra-nano-crystalline diamond (UNCD) nano-emitters were prepared by coating UNCD films on the tip of silicon nanowire (SiNW) templates by microwave plasma-enhanced chemical vapor deposition process. The electron field emission properties of the UNCD/SiNW nano-emitters varied markedly with the pre-seeding process for the SiNW-templates. The direct ultrasonication process is more efficient in the formation of the diamond nuclei than the carburization/ultrasonication process, yielding UNCD/SiNWs nano-emitters with better electron field emission properties. The electron field emission can be turned on at (E0)UNCD/SiNW4 = 3.75 V/µm, yielding a large electron field emission current density of (Je)UNCD/SiNW4 = 11.22 mA/cm2 at an applied field of 9.75 V/µm. These characteristics are significantly better than those of bare SiNWs or planar UNCD films.補正完
Unemployment, Vacancies, Wages
No full textPeter A. Diamond delivered his Prize Lecture on 8 December 2010 at Aula Magna, Stockholm University.Search frictions;
Synthesis of diamond using ultra-nanocrystalline diamonds as seeding layer and their electron field emission properties
No full textA modified nucleation and growth process was adopted so as to improve the electron field emission (EFE) properties of diamonds films. In this process, a thin layer of ultra-nanocrystalline diamonds (UNCD), instead of bias-enhanced-nuclei, were used as nucleation layer for growing diamond films in H2-plasma. The morphology of the grains changes profoundly due to such a modified CVD process. The geometry of the grains transform from faceted to roundish and the surface of grains changes from clear to spotty. The Raman spectroscopies and SEM micrographs imply that such a modified diamond films consist of UNCD clusters (~ 10–20 nm in size) on top of sp3-bonded diamond grains (~ 100 nm in size). Increasing the total pressure in CVD chamber deteriorated the Raman structure and hence degraded the EFE properties of the films, whereas either increasing the methane content in the H2-based plasma or prolonged the growth time improved markedly the Raman structure and thereafter enhanced the EFE properties of diamond films. The EFE properties for the modified diamond films can be turned on at E0 = 11.1 V/μm, achieving EFE current density as large as (Je) = 0.7 mA/cm2 at 25 V/μm applied field.補正完畢紙本CH
Investigation of a scale-up manufacturing approach for nanostructures by using a nanoscale multi-tip diamond tool
No full textIncreasing interest in commercializing functional nanostructured devices heightens the need for cost-effective manufacturing approaches for nanostructures. This paper presents an investigation of a scale-up manufacturing approach for nanostructures through diamond turning using a nanoscale multi-tip diamond tool (four tip tool with tip width of 150 nm) fabricated by focused ion beam (FIB). The manufacturing capacity of this new technique is evaluated through a series of cutting trials on copper substrates under different cutting conditions (depth of cut 100–500 nm, spindle speed 12–120 rpm). The machined surface roughness and nanostructure patterns are measured by using a white light interferometer and a scanning electron microscope, respectively. Results show that the form accuracy and integrity of the machined nanostructures were degraded with the increase of the depth of cut and the cutting speed. The burr and the structure damage are two major machining defects. High precision nano-grooves (form error of bottom width < 6.7 %) was achieved when a small depth of cut of 100 nm was used (spindle speed = 12 rpm). Initial tool wear was found at both the clearance cutting edge and the side edges of tool tips after a cutting distance of 2.5 km. Moreover, the nanometric cutting process was emulated by molecular dynamic (MD) simulations. The research findings obtained from MD simulation reveal the underlying mechanism for machining defects and the initialization of tool wear observed in experiments.</p
Redistribution of evoked activity across somatosensory cortical columns after altered tactile experience
No full textFabrication and field emission properties of ultra-nanocrystalline diamond lateral emitters
No full textField emission characteristics of ultra-nanocrystalline diamond (UNCD) have recently caught much attraction due to its importance in technological applications. In this work, we have fabricated lateral-field emitters comprised of UNCD films, which were deposited in CH4/Ar medium by microwave plasma-enhanced chemical vapor deposition method. The substrates, silicon-on-insulator (SOI) or SiO2-coated silicon, were pre-treated by mixed-powders-ultrasonication process for forming diamond nuclei to facilitate the synthesis of UNCD films on these substrates. Lateral electron field emitters can thus be fabricated either on silicon-on-insulator (SOI) or silicon substrates. The lateral emitters thus obtained possess large field enhancement factor (β = 1500–1721) and exhibit good electron field emission properties, regardless of the substrate materials used. The electron field emission can be turned on at 5.25–5.50 V/μm, attaining 5500–6000 mA/mm2 at 12.5 V/μm (100 V applied voltage).補正完
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