Wire Width Research Articles

Influence of Roll Diameter on Material Deformation and Properties during Wire Flat Rolling

The influence of roll diameter on the strain distribution, shape change, contact pressure, and damage value of a workpiece was investigated during wire flat rolling to control the material properties of the flattened wire. The flattened wires fabricated by the four different rolls were compared using finite element analysis. The strain inhomogeneity of the flat-rolled wire increased with the roll diameter; thus, the macroscopic shear bands were strengthened as the roll diameter increased during wire flat rolling. The contact width and lateral spreading of the flattened wire increased with the roll diameter; therefore, the reduction in area decreased with the roll diameter. The contour of the normal contact pressure on the wire surface exhibited a similar pattern regardless of the roll diameter. The contact pressure showed higher values at the entry, edge, and exit zones in the contact area. The distribution of the damage value varied with the roll diameter. The free surface region tended to have the peak damage value during the process; however, the center region exhibited the maximum damage value with the roll diameter. From the perspective of the damage value, the optimum roll diameter was in existence during wire flat rolling. The underlying cause of the different strain distributions, shape changes, and damage values of the flat-rolled wire was the different contact lengths originating from the different roll diameters during wire flat rolling.

Physical properties of amorphous molybdenum silicide films for single-photon detectors

We systematically investigated the physical properties of amorphous Mo x Si1−x films deposited by magnetron co-sputtering. The critical temperature T c of Mo x Si1−x films increases gradually with the Mo stoichiometry x, and the highest T c = 7.9 K was found in Mo0.83Si0.17, where homogeneous films with the maximum Mo content can be obtained. The thick films of Mo0.83Si0.17 show surprising degradation in which the onset of zero-resistivity is suppressed below 2 K. The thin Mo0.83Si0.17films, however, reveal robust superconductivity even with thickness d ≈ 2 nm. We also characterized wide microwires based on the 2 nm thin Mo0.8Si0.2 films with wire widths 40 and 60 μm, which show single-photon sensitivity at 780 nm and 1550 nm wavelength.

First Russian 220 kV Superconducting Fault Current Limiter (SFCL) For Application in City Grid

The superconducting fault current limiter (SFCL) for a nominal voltage of 220 kV and a rated current of 1200 A was developed by SuperOx company to be applied in high voltage substation in Moscow, Russia. The device is a three-phase dead-tank apparatus and is equipped with a closed-cycle cryocooling system. Liquid nitrogen serves simultaneously as a cooling and an insulating media. The device makes use of about 25 km of 12 mm wide high-performance 2G HTS wire with uniform properties along the length. High-voltage tests of the device were performed at Korea Electrotechnology Research Institute (KERI) in accordance with the IEEE C37.302-2015 test guide and Russian national standards for high voltage electrical equipment. The installation of the SFCL at substation in parallel with the existing air core reactors was completed in 2019. Since then, the device is in a daily operation. Over this period, SFCL has fully confirmed its design specifications including transmitting over 80 million kWh to customers and experiencing three fault current events.

Theoretical investigation of the signal performance of HgI2 x-ray converters incorporating a Frisch grid structure at mammographic energies

Active matrix, flat-panel imagers (AMFPIs) suffer from decreased detective quantum efficiency under conditions of low dose per image frame (such as for digital breast tomosynthesis, fluoroscopy and cone-beam CT) due to low signal compared to the additive electronic noise. One way to address this challenge is to introduce a high-gain x-ray converter called particle-in-binder mercuric iodide (PIB HgI2) which exhibits 3–10 times higher x-ray sensitivity compared to that of a-Se and CsI:Tl converters employed in commercial AMFPI systems. However, a remaining challenge for practical implementation of PIB HgI2 is the high level of image lag, which is believed to largely originate from the trapping of holes. Towards addressing this challenge, this paper reports a theoretical investigation of the use of a Frisch grid structure embedded in the converter to suppress hole signal—which would be expected to reduce image lag. The grid acts as a third electrode sandwiched between a continuous top electrode and pixelated bottom electrodes having a 100 μm pitch. Signal properties of such a detector are investigated as a function of VDR (the ratio of the voltage difference between the electrodes in the region below the grid to that above the grid), grid pitch (the center-to-center distance between two neighboring grid wires) and R GRID (the ratio of grid wire width to grid pitch) for mammographic x-ray energies. The results show that smaller grid pitch suppresses hole signal to a higher degree (up to ∼96%) while a larger gap between grid wires and higher VDR provide minimally impeded electron transport. Examination of the tradeoff between maximizing electron signal and minimizing hole signal indicates that a grid design having a grid pitch of 20 μm with R GRID of 50% and 65% provides hole signal suppression of ∼93% and ∼95% for VDR of 1 and 3, respectively.

Depinning behavior of the vortex domain wall at the asymmetric triangular notch in permalloy wires

The depinning field (H D) of vortex domain walls in a permalloy wire with an asymmetric triangle notch was investigated through magneto-optic Kerr effect (MOKE) microscopy and micromagnetic simulations. Wires of various widths with notches fixed on the wall’s incoming side angle were studied for various outgoing side angles (ϕ). The curves of H D of wall versus ϕ were measured by MOKE microscopy. Micromagnetic simulations were used to obtain curves of the H D of the wall versus ϕ. The maximum of such a curve of tail-to-tail -clockwise wall is known as the transition angle (ϕ T). The shape-anisotropic energy (E A) of the notch outgoing side wire and the exchange energy (E Ex) of the wall–notch interaction competed to influence the ϕ T value. Pinning potential was increased by the E Ex when ϕ was smaller than the ϕ T. Pinning potential was considerably reduced by the small E A when ϕ was larger than the ϕ T. Furthermore, the ϕ T value changed with the decrease in the depth of the notch because E A was influenced by notch depth.

Fabrication of Graphoepitaxial Gate-All-Around Si Circuitry Patterned Nanowire Arrays Using Block Copolymer Assisted Hard Mask Approach.

We demonstrate the fabrication of sub-20 nm gate-all-around silicon (Si) nanowire field effect transistor structures using self-assembly. To create nanopatterned Si feature arrays, a block-copolymer-assisted hard mask approach was utilized using a topographically patterned substrate with well-defined Si3N4 features for graphoepitaxially alignment of the self-assembled patterns. Microphase-separated long-range ordered polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block-copolymer-derived dot and line nanopatterns were achieved by a thermo-solvent approach within the substrate topographically defined channels of various widths and lengths. Solvent annealing parameters (temperature, annealing time, etc.) were varied to achieve the desired patterns. The BCP structures were modified by anhydrous ethanol to facilitate insertion of iron oxide features within the graphoepitaxial trenches that maintained the parent BCP arrangements. Vertical and horizontal ordered Si nanowire structures within trenches were fabricated using the iron oxide features as hard masks in an inductively coupled plasma (ICP) etch process. Cross-sectional micrographs depict wires of persistent width and flat sidewalls indicating the effectiveness of the mask. The aspect ratios could be varied by varying etch times. The sharp boundaries between the transistor components was also examined through the elemental mapping.

Photoelectric response characteristics of a novel translucent one-dimensional MAPbI<sub>3</sub>·DMF single crystal material

<p indent=0mm>Organic halide perovskites have broad application prospects in photoelectric detector due to their excellent photoelectric properties. Moreover, there has been growing interest in applying halide perovskites to semitransparent photovoltaics to achieve the highest combination of transparency and efficiency. In this paper, we aimed to prepare high-performance materials which are suitable for translucent optoelectronic devices using new preparation methods and explore the potential properties of these materials. We successfully synthesize a type of translucent linear MAPbI₃·DMF single crystal material with controllable size and good stability in atmospheric environment using the anti-solvent method. Toluene, which is often used as one of the surfactants to control the morphology of the perovskite films, was used as an anti-solvent in this paper. The growth of the one-dimensional (1D) single crystal wires was regulated by the control of the adsorbed toluene molecular at the interface, promoting the [PbI₆]⁴⁻octahedral unit in the precursor to assemble into a chain structure along the 1D direction. In addition, we could control the width and length of the single crystal wires via a slow cooling process. The width can reach tens of microns, and the length of the single crystal wires can be the centimeter level. The crystal structure of the transparent wire was analyzed using single crystal X-ray diffraction (XRD). The material exhibited a good 1D chain structure with an infinitely extended single edge-sharing octahedral lead halide chain {PbI₃}⁻ surrounded by CH₃NH₃⁺ (MA) and <italic>N</italic>,<italic>N</italic>-dimethylformamide (DMF). Through XRD characterization of the crystal structure after keeping the material at room temperature in air (~25°C, humidity ~40%) for a long time, we found that the single-crystal wire showed good stability in air. In addition, <italic>in situ </italic>heating XRD and <italic>in situ</italic> heating transmission electron microscopy (TEM) analyses showed that the morphology and crystal structure of the semi-transparent perovskite remained stable at 90°C, indicating that this material has good thermal stability. Further, an ultraviolet-visible absorption spectroscopy test showed that this material could absorb photons at <sc>300–800 nm,</sc> indicating that the obtained single crystal wire could absorb both ultraviolet and visible light. The material also exhibited a strong transmission effect for photons with wavelengths ranging from 500 to <sc>784 nm,</sc> indicating that the material has the semi-transparent property. According to the absorption spectrum, the transparency was calculated, and it was found that the transparency of single crystal materials increased in the range of more than <sc>500 nm,</sc> further implying that they have excellent translucence properties. Photoluminescence (PL) spectrum test showed that the single crystal material could emit <sc>~780 nm</sc> of fluorescence under laser irradiations of 409 and <sc>633 nm.</sc> Furthermore, using the Tauc plot method, we determined that this material has a bandgap of <sc>~1.58 eV,</sc> which is consistent with the PL test. In addition, this material shows good responsivity <sc>(7.13 A W^–1)</sc> with a response time of <sc>9.95 ms,</sc> making it suitable for photodetector applications. The good stability and photoelectric properties make this linear single crystal material an ideal candidate for the core absorbent layer of semi-transparent photodetector devices. This research work is expected to provide a reference for the development of transparent perovskite materials with high stability and good photoelectric properties.

Vortex Domain Wall Pinning Probability in Nanowires of Various Widths

We report the results of a micromagnetic simulation of vortex domain wall (VDW) dynamic pinning probability in 20-nm-thick planar permalloy wires with triangular notches and widths of 100, 200, and 300 nm. The notches have a fixed depth ratio of 30%, which is the depth divided by the wire width. Both the wire width and the applied field influenced the dynamic VDW pinning probability. The pinning probability decreased as the wire width increased. We observed a pinned domain wall (DW) structure around the notches and defined two types of pinning states, transverse DW pinning and VDW pinning. The 100-nm-wide wire had more transverse DW pinning–type events than did the 200- and 300-nm-wide wires. The 300-nm-wide wire had the lowest number of transverse DW pinning–type events. These results were caused by different wire widths having different DW energy densities and different pinning potential energy landscapes. When the applied field was larger than the Walker field, the wide wires easily led complex VDW motion.

On the switching current and the re-trapping current of tungsten nanowires fabricated by Focussed Ion Beam (FIB) technique

We report the superconducting properties of the tungsten (W) nanowires fabricated using focussed ion beam (FIB) technique having different wire widths of ∼120 nm and ∼290 nm. The transport properties of these wires were measured down to a temperature of 20 mK in a dilution refrigerator. We observed hysteretic current- voltage characteristics (IVCs) as a function of temperature, wherein the extend of hysteresis (difference between switching current and re-trapping current) is larger at lower temperature and diminishes near to the transition temperature. The temperature dependence of the switching current and re-trapping current were analysed using conventional models and found out to be of reasonable agreement with the models invoked. The re-trapping current agrees well with the thermal model incorporating phonon contribution in the heat dissipation process along with the electronic contribution. The equilibrium electron temperature calculated using the heat dissipation models at the critical current of the wires agrees well with respect to the transition temperature of the wire having a larger width, while for the wire of lower width, it is slightly elevated. Based on the analysis, it is believed that heat dissipation primarily because of Joule heating is the cause of the hysteretic current voltage characteristics of the nanowires.

Mo x Si1− x a versatile material for nanowire to microwire single-photon detectors from UV to near IR

We investigate material properties in Mo x Si1−x thin films with the goal of optimization for single-photon detection from UV to mid-IR wavelengths. Saturated internal detection efficiency appears to be related to film structure for this material. We demonstrate nanometer-wide meander devices with saturated internal efficiency at 370 nm wavelength and 3.4 K operation temperature. By reducing the film thickness in the optimized material, we demonstrate saturated internal detection efficiency at 1550 nm wavelength and 1 K operation temperature for micron-wide meander shaped single-photon detectors with wire widths up to 2.0 μm and active areas up to 362 × 362 μm2.

Study of Multiple Quantum Wire Hg0.8Cd0.2Te/CdTe Laser

The optoelectronic properties of Hg0.8Cd0.2Te/CdTe quantum wire laser are investigated, with emphasis on the effect of wire width (W) and barrier width (B) on the optical confinement factor (Г), the optical threshold gain (gth ) and the effect number of well (Nw ) on the confinement factor have been calculated. The laser operation system has been studied in the two cases; the number of well (2 and 3). It found that in our theoretical study, the values affect the work of a multiple laser system operating a number of well 2 was (W= 65nm, B = 40 nm), the value of optical confinement factor equals (Г= 0.055) and the amount of optical threshold gain was (gth = 38 cm −1). Further, the suitable values for multi quantum wire system is running a number of well 3 was (W= 42 nm, B = 60 nm), optical confinement factor equal to (Г= 0.048) and the threshold gain (gth = 42 cm −1). Theoretically, the principle of operation of a laser device depends on the resonator, the effective medium, and the stimulated emission of light radiation which is represented the important process in the work of device. It is found that the effect of optical confinement factor causes an increase in the reflectivity of laser beam in the cavity therefore decrease in the amount of optical threshold gain, noted that the amount of reflection was installed to study the change of other electronic characteristics of the multiple quantum wire.

Towards Fabrication of Atomic Dopant Wires via Monolayer Doping Patterned by Resist-Free LithographySupported by the Innovation Program of Shanghai Municipal Education Commission (Grant No. 2019-01-07-00-02-E00075), the Key R&D Program of Zhejiang Province (Grant No. 2019C01155), and the National Natural Science Foundation of China (Grant No. 61874072).

Fabrication of atomic dopant wires at large scale is challenging. We explored the feasibility to fabricate atomic dopant wires by nano-patterning self-assembled dopant carrying molecular monolayers via a resist-free lithographic approach. The resist-free lithography is to use electron beam exposure to decompose hydrocarbon contaminants in vacuum chamber into amorphous carbon that serves as an etching mask for nanopatterning the phosphorus-bearing monolayers. Dopant wires were fabricated in silicon by patterning diethyl vinylphosphonate monolayers into lines with a width ranging from 1 μm down to 8 nm. The dopants were subsequently driven into silicon to form dopant wires by rapid thermal annealing. Electrical measurements show a linear correlation between wire width and conductance, indicating the success of the monolayer patterning process at nanoscale. The dopant wires can be potentially scaled down to atomic scale if the dopant thermal diffusion can be mitigated.

Negative nonlocal and local voltages (resistances) in a quasi-one-dimensional superconducting aluminum structure

To study a nonlocal electron transport in an aluminum superconducting quasi-one-dimensional structure, we measured negative nonlocal (local) direct current voltages in the structure in a magnetic field near the critical temperature. The structure is a normal-superconducting at Tcn<T<Tcw (Tcn and Tcw are the critical temperatures for narrow and wide wires, respectively, making up this structure). Negative voltage arises due to a quasiparticle current flowing through the N-S interface. We plotted the experimental and theoretical temperature and magnetic-field dependences of current, resistance and voltage corresponding to the peak of negative voltage, taking into account either equilibrium or nonequilibrium superconducting fluctuations.

Creation and propagation of a single magnetic domain wall in 2D nanotraps with a square injection pad

Polycrystalline permalloy 2D nanotraps with a thickness of 20 nm were studied using a Lorentz microscope associated with micro-magnetic simulations. Each trap was designed to create a single head-to-head domain wall. The traps consist of a few nanowires with an in-plane dimension of w nm × 1000 nm (w = 150, 200 and 250 nm). Some structures with an injection pad were also designed to create a single domain wall and propagate it through the structure with the said injection pad. A few of them were patterned to study the nucleation and propagation behavior of such nucleated domain walls using both horizontal magnetic field and injection pad approaches. The case of a domain wall created at the first corner of the trap with a wire width of 200 nm was systematically studied, while single and multiple domain walls can also be created and propagated with or without an injection structure. The characteristics of such movements were exploited with an emphasis on a single head-to-head domain wall.

Biosensor Based on Ion-Sensitive Nanowire Field-Effect Transistor Using the Minimum Contact to the Floating Gate

The ion-sensitive field effect transistor (ISFET) is a promising tool for detecting intermolecular interactions, including biochemical ones. Using the ISFET, it is possible to recognize various mechanisms of specifically adsorbed substances. In addition, ISFET can be integrated with CMOS technology, which opens up new prospects for creating intelligent micro- and nanosystems. In this study, the influence of the design and technological parameters of the ISFET on charge sensitivity is investigated using numerical simulation. Two types of the ISFET design based on a completely depleted floating-gate SOI structure are presented. The designs differ by the way of forming the liquid medium–gate contact. The analytical dependences of the charge sensitivity of the ISFET, which make it possible to analyze the ISFET sensitivity, are obtained. It is shown that the limiting sensitivity is achievable on a composite nanowire structure with submicron dimensions. The sensitivity of the considered ISFET design with the characteristic size of 1.2 µm when an analyte is adsorbed is about 50 effective electron charges. The ISFET designed with submicron physical dimensions (wire width of 10 nm and wire length of 100 nm) has the sensitivity of 1 to 2 effective electron charges.

Controlled magnetic behaviour of Ni80Fe20 nanowire by a selection of nucleation pads

Magnetic nanowires are of technological importance as their magnetic properties can be controlled by their dimensions and shape. In soft magnetic nanowires (e.g. Ni 80 Fe 20 alloy or Permalloy), shape anisotropy has a very strong effect on their magnetic properties and thus the wire width and thickness control the domain patterns, nature of magnetization reversal, and the switching field. The switching field of a permalloy (Py) nanowire (NW) can be reduced substantially by attaching a microsized nucleation pad (NPD) to it. In this work, the OOMMF software package was used to perform micromagnetic simulations for selected NPD-NW structures. In this present study, we proved that the shape of the attached NPD is an important factor to consider. For instance, the switching field of structure comprises a triangular NPD (area = 0.25 μm2) with its head connected to a Py NW (20 nm wide) is about one fourth of the switching field of a square-like NPD-NW structure of the same size. Also the NPD size has an effect on the quality of the obtained hysteresis loop and thus it has to be comparable to the size of the NW for the sake of having a step-free hysteresis loop. These findings suggest that the rectangular NPD with its head connected to the NW may serve better than other shapes as it provides a directed motion for the domain walls to reach the NPD/NW interface easily. Thus it gives the highest reduction in the switching field of the Py nanowire in addition to a step-free hysteresis loop when the NPD size is 0.01 μm2.

Dimensional crossover in spin Hall oscillators

Auto-oscillations of magnetization driven by direct spin current have been previously observed in multiple quasi-zero-dimensional (0D) ferromagnetic systems such as nanomagnets and nanocontacts. Recently, it was shown that pure spin Hall current can excite coherent auto-oscillatory dynamics in quasi-one-dimensional (1D) ferromagnetic nanowires but not in quasi-two-dimensional (2D) ferromagnetic films. Here we study the 1D to 2D dimensional crossover of current-driven magnetization dynamics in wire-based Pt/$\mathrm{Ni}_{80}\mathrm{Fe}_{20}$ bilayer spin Hall oscillators via varying the wire width. We find that increasing the wire width results in an increase of the number of excited auto-oscillatory modes accompanied by a decrease of the amplitude and coherence of each mode. We also observe a crossover from a hard to a soft onset of the auto-oscillations with increasing the wire width. The amplitude of auto-oscillations rapidly decreases with increasing temperature suggesting that interactions of the phase-coherent auto-oscillatory modes with incoherent thermal magnons plays an important role in suppression of the auto-oscillatory dynamics. Our measurements set the upper limit on the dimensions of an individual spin Hall oscillator and elucidate the mechanisms leading to suppression of coherent auto-oscillations with increasing oscillator size.

Current-induced linear motion of antiferromagnetically coupled skyrmion-like bubble domains stabilized without Dzyaloshinskii–Moriya interaction

Magnetic domains are used to represent binary digits in magnetic memories. In domain-motion magnetic memories, the domain must move longitudinally along a ferromagnetic nanowire. Antiferromagnetically coupled magnetic skyrmions, which are domains meeting this requirement, can be stabilized via the Dzyaloshinskii–Moriya interaction (DMI) in an antiferromagnetically coupled bi-layered perpendicularly magnetized thin wire. We find that antiferromagnetically coupled skyrmion-like bubble domains (BDs) may be produced in such a wire without DMI. The stability and the dynamics of such domains are studied by micromagnetic simulations based on the Landau–Lifshitz–Gilbert equation. The BDs in the two layers have clockwise and anti-clockwise Bloch type domain walls, so the BD cores have anti-parallel magnetic moments and are antiferromagnetically coupled. Domain size decreases with decreasing wire width and/or increasing antiferromagnetic coupling strength of the wire. The minimum value of the BD radius is about 10 nm. When a spin-polarized current flows through the wire, the BD moves with the current.

Experimental observation and numerical investigation of imposed pattern formation in magnetized plasmas by a wide wire mesh

In this paper, the formation of imposed patterns due to placing a wide wire mesh (‘waffle’ electrode) in the bulk of a strongly magnetized (B ⩾ 1 T) plasma is investigated both experimentally and numerically. A new double head electrostatic probe was designed for the experiments that allows for measurements of the floating potential beneath the mesh in the magnetized plasma. The measurements using this probe revealed that due to the presence of the ‘waffle’ electrode in the bulk of the magnetized plasma, an organized pattern appears in the plasma potential. As a result of this imposed pattern, when dust particles were added to the experiments, they became trapped beneath the edges of the ‘waffle’ electrode. The effects of placing a wire mesh in the bulk of a magnetized plasma were further investigated using fluid and particle-in-cell (PIC) simulations. These simulations were able to qualitatively reproduce the experimental observations. The results of the simulations showed that the imposed patterns arise due to differences in the cross-field transport of the electrons and ions in the presence of magnetic field.

SAT-Based On-Track Bus Routing

In modern integrated circuit design, bus routing is a challenge because of complex design rules and wiring constraints. Despite extensive research, state-of-the-art in bus routing is not effective when nonuniform tracks, various obstacles, wire width constraints, and multiple spacing rules should be handled simultaneously. A new bus routing framework proposed in this article is based on maze routing and Boolean satisfiability. It produces high-quality results quickly and allows for additional optimizations, such as minimizing wire length on the critical paths. A number of challenging bus routing benchmarks appeared in 2018 ICCAD Contest. Experiments on these benchmarks not only show that the framework is faster than the winners of the competition and previous work but also produces better results, improving the overall cost by 12% while at the same time minimizing the number of spacing violations.