Nanowire Configuration Research Articles

An investigation of rapid surface melting in nanowires

The investigation into virtual melting phenomena in nanowires holds significant relevance owing to its profound impact on material durability under extreme loading conditions. Thus, the exploration of this pivotal plastic deformation mechanism is undertaken utilizing the phase-field methodology. Employing a monolithic solver, we solve the coupled highly nonlinear time-dependent Ginzburg–Landau equation and dynamic elasticity equation. Our analysis encompasses the consideration of surface tension stress in conjunction with a coherent solid–liquid interface subjected to uniaxial transformation strain, thereby unveiling intriguing facets of melting phenomena. The investigation delves into the influence of transformation strain, kinetic coefficient, and temperature on the thickness of the solid–liquid interface and its corresponding velocity. This analysis is conducted through meticulous comparison with existing experimental data and analytical solutions. Moreover, employing the phase-field method yields precise descriptions of the system kinetics, capturing virtual melting phenomena in both pristine and flawed nanowire configurations.

Heat transfer and visualization of flow boiling on nanowire surfaces in the microchannel

Enhancing heat transfer efficiency is crucial in heat exchange equipment. Although previous studies have focused on developing micro/nano-structured surfaces, further exploration into how surface structure can improve heat transfer efficiency (H) by altering bubble dynamics is still needed. This study aimed to innovatively analyze the impact of titanium carbide (TiC) nanowire heights—specifically 4 µm and 12 µm—on boiling heat transfer performance. Conducted under varying heat flux (Q) (50–200 W/m2) and mass flux (G) (200–300 kg/m2·s), our experiments assessed H, pressure drop (P), and local boiling curves. Using a high-speed camera, we observed complex periodic flow patterns on the 4 µm nanowire surface, including elongated bubble formation, expansion, local dryout, and subsequent fluid rewetting. Results showed that the 12 µm nanowire surface increased H by up to 19.84 % in single-phase conditions, while the 4 µm nanowire surface increased H by up to 27.9 % in two-phase conditions. These findings highlight the significant role of nanowire length and arrangement in optimizing boiling heat transfer performance. This work lays a foundation for further investigations into diverse nanowire materials and configurations.

Site-selective core/shell deposition of tin on multi-segment nanowires for magnetic assembly and soldered interconnection

The field of nanotechnology continues to grow with the ongoing discovery and characterization of novel nanomaterials with unconventional size-dependent properties; however, the ability to apply modern manufacturing strategies for practical device design of these nanoscale structures is significantly limited by their small size. Although interconnection has been previously demonstrated between nanoscale components, such approaches often require the use of expensive oxidation-resistant noble metal materials and time-consuming or untargeted strategies for welded interconnection such as laser ablation or plasmonic resonance across randomly oriented component networks. In this work, a three-segment gold–nickel–gold nanowire structure is synthesized using templated electrodeposition and modified via monolayer-directed aqueous chemical reduction of tin solder selectively on the gold segments. This core/shell nanowire structure is capable of directed magnetic assembly tip-to-tip and along substrate pads in network orientation. Upon infrared heating in a flux vapor atmosphere, the solder payload melts and establishes robust and highly conductive wire–wire joints. The targeted solder deposition strategy has been applied to various other multi-segment gold/nickel nanowire configurations and other metallic systems to demonstrate the capability of the approach. This core/shell technique of pre-loading magnetically active nanowires with solder material simplifies the associated challenges of size-dependent component orientation in the manufacture of nanoscale electronic devices.

Application of the quantum model of the rotating wave approximation to the generation of spin waves in nanowires

The paper simulates systems in which two types of spin waves can occur, propagating in opposite directions. To achieve this, the quantum slow-wave approximation is employed, allowing for the determination of the probability distribution of occupied states in a quantum two-particle system subjected to perturbations, commonly referred to as Rabi oscillations. This model is specifically applied to a configuration of parallel nanowires exposed to an external electromagnetic wave within the microwave range. The study explores a potential application of the investigated nanostructures in the development of a device for detecting electromagnetic fields.

Effects of Static Electric Fields on the Excitations of Silver Nanowire Dimers.

We theoretically studied the introduction of static electric fields to Ag10 nanowire dimer systems, including the effects of this field on optical absorption characteristics and the orbitals responsible for these excitations. Linear-response time-dependent density functional theory computations were performed on three distinct dimer systems: end-to-end, parallel, and 90° angle dimer systems separated by a closest interparticle distance of 7.0 Å. The calculations were performed in the presence of a 0.1 V/Å electric field strength applied in the z and y directions. The orientation of the dimer system and the direction of the applied static electric field each play a significant role in the resulting absorption spectra and the electronic structure of the nanowires. As a result, a dimer system can exhibit a blue shift for the longitudinal excitation and a red shift for the transverse excitation in the presence of one direction of the static electric field but not for the other direction. Notably, the electron density shifts from one nanowire to the other in the presence of the static electric field. Changes in optical characteristics and electronic structure suggest that the usage of a static electric field with a particular spatial configuration of nanowires provides a way to tune the optical properties of the system.

In‐Plane Selective Area Epitaxy of InAsSb Nanowire Networks for High‐Performance Scalable Infrared Photodetectors

AbstractCMOS‐compatible III–V semiconductor nanowire infrared photodetectors have attracted extensive research interest in various fields such as Si photonics and gas sensors. However, the traditional vertical configuration of nanowires limits their applications at the circuit level. Here, an in‐plane selective area epitaxy route is developed to grow large‐scale InAsSb nanowire networks on patterned Si substrates. By precisely tuning the growth parameters, the well‐aligned InAsSb nanowire networks with good selectivity are successfully achieved. Detailed structural studies confirm that there is a sharp interface between the InAsSb nanowire and the substrate. On the basis of optoelectronic measurements, it is confirmed that the fabricated InAsSb nanowire network photodetectors exhibit a low dark current density (≤2 mA cm−2) and a wide spectral response (1200–1650 nm) at room temperature, covering the important telecommunication bands. Moreover, these devices present a high on‐off ratio, large responsivity, high detectivity, and rapid response speed at zero bias voltage. At the illumination wavelength of 1200 nm, the on‐off ratio, responsivity, detectivity, and response time of a double nanowire networks photodetector can reach 2680, 286.9 mA W−1, 1.4 × 1010 Jones and 75.3 µs, respectively. This work offers a straightforward approach to in situ fabricating high‐performance scalable nanowire photodetectors.

Highly Responsive Switchable Broadband DUV-NIR Photodetector and Tunable Emitter Enabled by Uniform and Vertically Grown III-V Nanowire on Silicon Substrate for Integrated Photonics.

Low-dimensional semiconductor nanostructures, particularly in the form of nanowire configurations with large surface-to-volume-ratio, offer intriguing optoelectronic properties for the advancement of integrated photonic technologies. Here, a bias-controlled, superior dual-functional broadband light detecting/emitting diode enabled by constructing the aluminum-gallium-nitride-based nanowire on the silicon-platform is reported. Strikingly, the diode exhibits a stable and high responsivity (R) of over 200mAW-1 covering an extremely wide operation band under reverse bias conditions, ranging from deep ultraviolet (DUV: 254nm) to near-infrared (NIR: 1000nm) spectrum region. While at zero bias, it still possesses superior DUV light selectivity with a high off-rejection ratio of 106. When it comes to the operation of the light-emitting mode under forward bias, it can achieve large spectral changes from UV to red simply by coating colloid quantum dots on the nanowires. Based on the multifunctional features of the diodes, this study further employs them in various optoelectronic systems, demonstrating outstanding applications in multicolor imaging, filterless color discrimination, and DUV/NIR visualization. Such highly responsive broadband photodetector with a tunable emitter enabled by III-V nanowire on silicon provides a new avenue toward the realization of integrated photonics and holds great promise for future applications in communication, sensing, imaging, and visualization.

Diameter-dependent ultra-high thermoelectric performance of ZnO nanowires

Zinc oxide (ZnO) shows great potential in electronics, but its large intrinsic thermal conductivity limits its thermoelectric applications. In this work, we explore the significant carrier transport capacity and diameter-dependent thermoelectric characteristics of wurtzite-ZnO 〈0001〉 nanowires based on first-principles and molecular dynamics simulations. Under the synergistic effect of band degeneracy and weak phonon–electron scattering, P-type (ZnO)73 nanowires achieve an ultra-high power factor above 1500 μW⋅cm−1⋅K−2 over a wide temperature range. The lattice thermal conductivity and carrier transport properties of ZnO nanowires exhibit a strong diameter size dependence. When the ZnO nanowire diameter exceeds 12.72 Å, the carrier transport properties increase significantly, while the thermal conductivity shows a slight increase with the diameter size, resulting in a ZT value of up to 6.4 at 700 K for P-type (ZnO)73. For the first time, the size effect is also illustrated by introducing two geometrical configurations of the ZnO nanowires. This work theoretically depicts the size optimization strategy for the thermoelectric conversion of ZnO nanowires.

Magnetic properties of oxide Mn nanowires on vicinal Au surface

The development of quantum computing or magnetic storage systems requires the search for magnetic nanostructures with multiple magnetic configurations with controllable quantum spin states. The study of the magnetic properties of metal oxide nanowires is of particular importance for the development of these technological implementations. The present work is devoted to an ab initio study of the magnetic properties of Mn and Mn oxide (MnO) nanowires on vicinal Au surfaces with different step edge geometries. The existence of ferromagnetic and antiferromagnetic configurations of Mn and MnO nanowires on vicinal Au surfaces was found. The effect of oxidations and surface geometry on the appearance of ferromagnetic or antiferromagnetic properties of the nanowire was revealed. The ground state of pure Mn nanowires was shown to be dependent on the surface structure. At the same time, the ground state of oxide Mn nanowires is antiferromagnetic on all studied vicinal surfaces and did not depend on the surface structure. We observed an increase in the exchange interaction energy in nanowires under surface oxidation. The exchange interaction between manganese atoms in MnO nanowires is much stronger than in pure Mn nanowires.

Regulating the Electronic Structure of Ni Sites in Ni(OH)2 by Ce Doping and Cu(OH)2 Coupling to Boost 5-Hydroxymethylfurfural Oxidation Performance.

Biomass is a sustainable and renewable resource that can be converted into valuable chemicals, reducing the demand for fossil energy. 5-Hydroxymethylfurfural (HMF), as an important biomass platform molecule, can be converted to high-value-added 2,5-furandicarboxylic acid (FDCA) via a green and renewable electrocatalytic oxidation route under mild reaction conditions, but efficient electrocatalysts are still lacking. Herein, we rationally fabricate a novel self-supported electrocatalyst of core-shell-structured copper hydroxide nanowires@cerium-doped nickel hydroxide nanosheets composite nanowires on a copper mesh (CuH_NWs@Ce:NiH_NSs/Cu) for electrocatalytically oxidizing HMF to FDCA. The integrated configuration of composite nanowires with rich interstitial spaces between them facilitates fast mass/electron transfer, improved conductivity, and complete exposure of active sites. The doping of Ce ions in nickel hydroxide nanosheets (NiH_NSs) and the coupling of copper hydroxide nanowires (CuH_NWs) regulate the electronic structure of the Ni active sites and optimize the adsorption strength of the active sites to the reactant, meanwhile promoting the generation of strong oxidation agents of Ni3+ species, thereby resulting in improved electrocatalytic activity. Consequently, the optimal CuH_NWs@Ce:NiH_NSs/Cu electrocatalyst is able to achieve a HMF conversion of 98.5% with a FDCA yield of 97.9% and a Faradaic efficiency of 98.0% at a low constant potential of 1.45 V versus reversible hydrogen electrode. Meanwhile, no activity attenuation can be found after 15 successive cycling tests. Such electrocatalytic performance suppresses most of the reported Cu-based and Ni-based electrocatalysts. This work highlights the importance of structure and doping engineering strategies for the rational fabrication of high-performance electrocatalysts for biomass upgrading.

Nucleation and Stability of Toron Chains in Non-Centrosymmetric Magnetic Nanowires.

This work analyzes the magnetic configurations of cylindrical nanowires with a bulk Dzyaloshinskii-Moriya interaction and easy-plane anisotropy. We show that this system allows the nucleation of a metastable toron chain even when no out-of-plane anisotropy exists in the nanowire's top and bottom surfaces, as usually required. The number of nucleated torons depends on the nanowire length and the strength of an external magnetic field applied to the system. The size of each toron depends on the fundamental magnetic interactions and can be controlled by external stimuli, allowing the use of these magnetic textures as information carriers or nano-oscillator elements. Our results evidence that the topology and structure of the torons yield a wide variety of behaviors, revealing the complex nature of these topological textures, which should present an exciting interaction dynamic, depending on the initial conditions.

Tunable electrical anisotropy of metallic nickel by self-assembly nanowires

We fabricated a metallic nickel with an electrical anisotropy by alignment of nanowires. It is found that the electrical anisotropy of the metallic nickel can be effectively modulated by the geometric configuration of nanowires, which can be tuned by the concentration of Ni2+ and the strength of the external magnetic field, respectively. The ratio of resistivity between perpendicular and parallel direction for the metallic nickel is optimized to be 2.03, when the nanowires are synthesized at a condition that the concentration of Ni2+ is 0.05 M assisted by an external magnetic field. This work provides a path for producing anisotropic metals, which could have potential applications in areas such as thermoelectricity or thermal spintronics.

Mesoporous Pt@Pt-skin Pt3Ni core-shell framework nanowire electrocatalyst for efficient oxygen reduction

The design of Pt-based nanoarchitectures with controllable compositions and morphologies is necessary to enhance their electrocatalytic activity. Herein, we report a rational design and synthesis of anisotropic mesoporous Pt@Pt-skin Pt3Ni core-shell framework nanowires for high-efficient electrocatalysis. The catalyst has a uniform core-shell structure with an ultrathin atomic-jagged Pt nanowire core and a mesoporous Pt-skin Pt3Ni framework shell, possessing high electrocatalytic activity, stability and Pt utilisation efficiency. For the oxygen reduction reaction, the anisotropic mesoporous Pt@Pt-skin Pt3Ni core-shell framework nanowires demonstrated exceptional mass and specific activities of 6.69 A/mgpt and 8.42 mA/cm2 (at 0.9 V versus reversible hydrogen electrode), and the catalyst exhibited high stability with negligible activity decay after 50,000 cycles. The mesoporous Pt@Pt-skin Pt3Ni core-shell framework nanowire configuration combines the advantages of three-dimensional open mesopore molecular accessibility and compressive Pt-skin surface strains, which results in more catalytically active sites and weakened chemisorption of oxygenated species, thus boosting its catalytic activity and stability towards electrocatalysis.

Hierarchically Oriented Jellyfish‐Like Gold Nanowires Film for Elastronics

AbstractStretchable electronics (i.e., Elastronics) are essential to the realization of next‐generation wearable bioelectronics for personalized medicine, due to their unique skin‐conformal features ideal for seamless integration with the human body. Significant progress has been made to nanowire‐based elastronics with promising applications ranging from electronic‐skin to advanced energy harvest systems. However, it remains a key challenge to rationally control over the nanowire morphology and configurations to achieve desired multifunctionality. Herein, a stretchable jellyfish‐like gold nanowires film with high conductivity and stretchability is presented by using gold nanostar‐seeded nanowire growth method. They exhibit unique hierarchically oriented structure with gold nanostars as the multi‐branched active sites (top layer) and vertically intertwined nanowires (bottom layer) trailing below the nanostars. Such nanowires film can be stretched up to 200% with a retaining low normalized resistance of 13.8 due to the unique hierarchical structure. Furthermore, the film can be used as stretchable supercapacitor with a 92% capacitance retention and superior durability even after 5000 electrochemical scanning cycles. The method is general, which can be further expanded to other metallic seeds, hence, representing a low‐cost yet efficient strategy for the fabrication of stretchable elastronics and robust energy storage devices for on‐body biosensing and bioelectronics.

Magnonic contribution in thermal conductance of a nanostructure in the presence of magnon-phonon interaction.

Using Green's function method, we study thermal transport properties of magnons transmitting through a magnetic nanowire at a certain temperature. In a small part of the nanowire in the middle, we are supposed to have two types of local and nonlocal magnon-phonon interactions. The self-energies for this part due to the other parts of the wire are analytically derived. First, we calculate the phonon mode-dependent magnon transmission coefficient in the classical canonical ensemble. Then, by taking an average of the phonon modes, we obtain the total magnon transmission coefficient and use it for computing magnon thermal conductance. We use the model to investigate four configurations of magnetic nanowires composed of ferromagnetic and/or antiferromagnetic parts. The results show that, when the scattering region has an antiferromagnetic alignment, the magnons transfer in the structure more weakly than for ferromagnetic alignment. There is a phonon-assisted mechanism for tunneling of magnons which are transmitted through the gap or between magnon quasifrequencies of the scattering region. Generally, in the same values for local and nonlocal strengths of magnon-phonon interaction, the nonlocal one has a greater effect on the magnonic thermal transport properties. We found the fitting functions in order to relate the macroscopic quantities of the magnon transmission coefficient and thermal conductivity to microscopic parameters of the strengths of the local and nonlocal magnon-phonon interaction.

Directed Self‐Assembly for Dense Vertical III–V Nanowires on Si and Implications for Gate All‐Around Deposition

AbstractFabrication of next generation transistors calls for new technological requirements, such as reduced size and increased density of structures. Development of cost‐effective processing techniques to fabricate small‐pitch vertical III–V nanowires over large areas will be an important step toward realizing dense gate all‐around transistors, having high electron mobility, and low power consumption. It is demonstrated here, how arrays of III–V nanowires with a controllable number of rows, ranging from one single row up to bands of 500 nm, can be processed by directed self‐assembly (DSA) of block copolymer (BCP). Furthermore, it is shown that the DSA‐orientation with respect to the substrate's crystal direction affects the nanowire facet configuration, and thereby the nanowire spacing and gate all‐around deposition possibilities. A high χ poly(styrene)‐block‐poly(4‐vinylpyridine) BCP pattern directed by electron beam lithography‐defined guiding lines is transferred into silicon nitride. The silicon nitride is then used as a selective area metal‐organic vapor phase epitaxy mask atop an indium arsenide (InAs) buffer layer on a silicon platform to grow vertical InAs nanowires at 44–60 nm row pitch. Finally, deposition of high‐κ oxide and titanium nitride at this high pattern density is demonstrated, to further illustrate the considerations needed for next generation transistors.

Hydrogen evolution reaction activity of III-V heterostructure nanowires

III-V materials have gained great interest in materials science community since a few decades due to their versatile properties. Experimenting with the crystal phase, dimensional confinement, chemical environment and external conditions open-up a window to finely tune the properties of material of interest at atomic scale. The density functional theory-based investigation of III-V semiconductors under heterostructure nanowire configuration is presented with specific focus on the electronic dispersion and band alignment. The combination of GaSb core having triangular(T)/circular(R) cross-sections with GaP and GaAs shells reveal formation of type-II heterostructure with moderate electronic band gap suggesting promising application in photocatalysis and photovoltaics. Motivated by these results, we have investigated the catalytic activity of the heterostructure nanowires towards hydrogen evolution reaction (HER). Interesting results showing reliable HER activity over different surface sites of the nanowires evidently approve their importance as an active HER catalyst. Furthermore, being within nano regime, the present systems suggest cost-effective production of HER catalyst as compared to the conventional novel metal-based catalysts.

Large-scale preparation of ultra-long ZnSe–PbSe heterojunction nanowires for flexible broadband photodetectors

Flexible photodetectors show great applications in wearable electronics such as health monitoring and the Internet of Things. In this study, we have prepared ultralong ZnSe–PbSe heterojunction nanowires with a length of 20 μm in gram-scale by an in-situ cation exchange reaction. The produced PbSe nanoparticles on the ZnSe nanowire configuration are close to an ideal heterojunction system due to the small lattice mismatch of 7.4% in the (111) direction. The Ohmic contact is formed for nanowire photodetectors. The ZnSe–PbSe heterojunction nanowire photodetector exhibits a broadband photoresponse with the peak responsivity of 40 A W −1 while the ZnSe nanowire photodetector shows a narrowband photoresponse of 5 A W −1 , as a result of its extended absorption across the entire UV-visible-NIR. Electrons are transported from PbSe to ZnSe while holes are trapped at PbSe, and electrons are extracted to an external circuit by an Al electrode, resulting in a high gain of the photoconductor. The broadband photoresponse, the large linear dynamic range of 66 dB, the fast response speed of 0.02 s and the protracted cycle of 5000 show the feasibility of the flexible heterojunction photodetector.

HADOKEN: An open-source software package for predicting electron confinement effects in various nanowire geometries and configurations

We present an open-source software package, HADOKEN (High-level Algorithms to Design, Optimize, and Keep Electrons in Nanowires), for predicting electron confinement/localization effects in nanowires with various geometries, arbitrary number of concentric shell layers, doping densities, and external boundary conditions. The HADOKEN code is written in the MATLAB programming environment to aid in its readability and general accessibility to both users and practitioners. We provide several examples and outputs on a variety of different nanowire geometries, boundary conditions, and doping densities to demonstrate the capabilities of the HADOKEN software package. As such, the use of this predictive and versatile tool by both experimentalists and theorists could lead to further advances in both understanding and tailoring electron confinement effects in these nanosystems. Program summaryProgram Title: HADOKENCPC Library link to program files:https://doi.org/10.17632/jyzk4gfytx.1Licensing provisions: GNU General Public License 3Programming language: MATLABNature of problem: HADOKEN utilizes iterative finite element methods to solve coupled Schrödinger and Poisson equations for heterostructure core–shell nanowires with arbitrary cross-sectional geometries. The user-friendly program outputs graphical results of electronic energies, densities, wavefunctions, and band profiles for various user-supplied input parameters.Solution method: iterative solution of coupled Schrödinger and Poisson equations using finite element methods and sparse matrix linear algebra.

Characterization of optical and nonlinear properties of individual GaP nanowires using optical tweezers

Semiconductor nanowires (NWs) offer multiple advantages for designing novel optoelectronic devices, such as small footprint, high quantum efficiency, high nonlinear susceptibility. Gallium phosphide (GaP) is one of the attractive materials owing to its low optical absorption and high nonlinear susceptibility. However NWs should be transferred to planar substrates for optical studies, which do not allow efficient signal outcoupling. We demonstrate efficient second harmonic generation in individual GaP nanowires trapped using optical tweezers. Such vertically arranged configuration of NW allows to both efficiently generate second harmonic and to probe linear optical response using broadband light source. Such experiment allows to examine interplay between harmonic generation efficiency and NW dimensions.