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Investigating the phonon-surface scattering mechanism is essential for the evaluation of thermal transport in nanostructures. The theoretical description to quantify this mechanism remains to be developed at the atomic scale. This work presents a phonon wave packet method to study the phonon-surface scattering behavior at rough surfaces. We obtain the specularity distribution dependent on phonon polarization, wavelength, and surface roughness. The reflection of the diffuse wave packet is primarily attributed to the surface shadowing effect at a higher incident angle, surface disorder, and surface-induced localized modes. Taking the wavevector-dependent specularity data as input, the thermal conductivity of silicon nanowires is calculated based on the Boltzmann Transport Equation. Our specularity model provides an accurate evaluation for predicting thermal conductivity. This work offers an atomic-level analysis for phonon-surface interaction, which is helpful for the understanding of thermal transport in nanostructures. [ABSTRACT FROM AUTHOR]

Silicon, renowned for its remarkable energy density, has emerged as a focal point in the pursuit of high-energy storage solutions for the next generation. Nevertheless, silicon electrodes are known to undergo significant volume expansion during the insertion of lithium ions, leading to structural deformation and the development of internal stresses, and causing a rapid decline in battery capacity and overall lifespan. To gain deeper insights into the intricacies of charge rate effects, this study employs a combination of in situ measurements and computational modeling to elucidate the cyclic performance of composite silicon electrodes. The findings derived from the established model and curvature measurement system unveil the substantial alterations in stress and deformation as a consequence of varying charge rates. Notably, the active layer experiences compressive forces that diminish as the charge rate decreases. At a charge rate of 0.2, the active layer endures a maximum stress of 89.145 MPa, providing a comprehensive explanation for the observed deterioration in cycling performance at higher charge rates. This study not only establishes a fundamental basis for subsequent stress analyses of silicon electrodes but also lays a solid foundation for further exploration of the impact of charge rates on composite silicon electrodes. [ABSTRACT FROM AUTHOR]

The laser power mediated changes in the Raman line shape have been considered in terms of interference between discrete phonon states ρ and the electronic continuum states ϰ contributed by Urbach tail states. The laser-induced effects are treated in terms of the increase in the surface temperature and thereby the scaling of electronic disorder, i.e., Urbach energy, which can further contribute to the electron–phonon interactions. Therefore, the visualization of this effect is attempted analytically as a perturbation term in the Hamiltonian, which clearly accounts for the observed changes with laser power. This has been investigated based on the experimental results of laser power dependent Raman spectra of bulk EuFeO3 and silicon nanowires, which are found to provide convincing interpretations. [ABSTRACT FROM AUTHOR]

Metal–Organic Polymers (MOPs) have attracted growing attention for lithium-ion battery (LIB) applications due to their merits in orderly ionic transportation and robust structure stability in electrochemical reactions. However, they suffer from poor electronic conductivity. In this work, we apply first-principles density functional theory to explore the potential of three one-dimensional (1D) electrically conductive C6H2S4TM (TM = Fe, Co, and Ni) MOPs with the π–d conjugated coordination as anode materials for Li+ ions storage. Our theoretical results reveal that these 1D MOPs possess a superior theoretical capacity of over 748 mA h g−1. In particular, the 1D C6H2S4Ni MOP shows an exceptional theoretical specific capacity of 1110 mA h g−1 based on the three-electron transferring reaction, which significantly outperforms the traditional graphite-based anode material in LIBs. Moreover, the resonant charge transfer between Ni metal and ligand within the 1D C6H2S4Ni MOP reduces the diffusion energy barrier of the Li atoms when they migrate on the surface of the MOP. The ultrahigh theoretical specific capacity of the C6H2S4Ni MOP predicts that it can be a promising anode material for LIBs. [ABSTRACT FROM AUTHOR]

An analytical device physics model is presented for determining the energy conversion efficiency of semiconductor nanowire array-based radial (core–shell) p-i-n junction betavoltaic cells for two- and three-dimensional radioisotope source geometries. Optimum short-circuit current density J sc , open-circuit voltage V oc , fill factor F F , and energy conversion efficiency η are determined for various nanowire properties, including dopant concentration, nanowire length, core diameter, and shell thickness, for Si, GaAs, and GaP material systems. A maximum efficiency of 8.05 % was obtained for GaP nanowires with diameter 200 nm (p-core diameter, i-shell, and n-shell thicknesses of 24, 29.4, and 58.6 nm, respectively), length 10 μ m , acceptor and donor concentrations of 10 19 and 5 × 10 18 cm − 3 , respectively, and a 3D source geometry. [ABSTRACT FROM AUTHOR]

Hyperdoped silicon is a promising material for near-infrared light detection, but to date, the device efficiency has been limited. To optimize photodetectors based on this material that operate at room temperature, we present a detailed study on the electrical nature of gold-hyperdoped silicon formed via ion implantation and pulsed-laser melting (PLM). After PLM processing, oxygen-rich and gold-rich surface layers were identified and a wet etch process was developed to remove them. Resistivity and Hall effect measurements were performed at various stages of device processing. The underlying gold-hyperdoped silicon was found to be semi-insulating, regardless of whether the surface gold was removed by etching or not. We propose a Fermi level pinning model to describe the band bending of the transformed surface layer and propose a promising device architecture for efficient Au-hyperdoped Si photodetectors. [ABSTRACT FROM AUTHOR]

Roughly, 50% of primary energy worldwide is rejected as waste heat over a wide range of temperatures. Waste heat above 573 K has the highest Carnot potential (> --> 50 %) to be converted to electricity due to higher Carnot efficiency. Thermoelectric (TE) materials have gained significant attention as potential candidates for efficient thermal energy conversion devices. Silicon nanowires (SiNWs) are promising materials for TE devices due to their unique electrical and thermal properties. In this study, we report the successful fabrication of high-quality double-sided SiNW arrays using advanced techniques. We engineered the double-sided structure to increase the surface area and the number of TE junctions, enhancing TE energy conversion efficiency. We also employed non-agglomeration wire tip engineering to ensure uniformity of the SiNWs and designed effective Ohmic contacts to improve overall TE efficiency. Additionally, we post-doped the double-sided SiNW arrays to achieve high electrical conductivity. Our results showed a significant improvement in the TE performance of the SiNW array devices, with a maximum figure-of-merit (ZT) value of 0.24 at 700 K, fabricated from the single SiNW with ZT of 0.71 at 700 K in our previous work [Yang et al., Nat. Commun. 12(1), 3926(2021)]. [ABSTRACT FROM AUTHOR]

Copper (Cu) interconnections have been widely used in advanced electronic packaging due to their outstanding thermal and electric properties. Preparing a smooth and uniform Cu seed thin layer is one of the critical processes to obtain high-reliability Cu interconnections. The barrier layer between Cu and silicon (Si) devices is necessary to prevent the inter-diffusion between Cu and Si. However, little work has been done on the surface roughness analysis of the Cu seed layer deposited on the diffusion barrier layer. In this paper, the influences of deposition thickness, incident energy, barrier layer temperature, and surface morphology on the surface roughness of the Cu seed layer deposited on α-titanium (α-Ti) barrier layer were studied in detail by the molecular dynamics (MD). The simulation results indicated that appropriate parameters have a beneficial effect on reducing the surface roughness, and the surface morphology of the Cu seed layer strongly connects with that of the barrier layer. These results provided a foundation for optimizing the quality of the Cu seed layer. [ABSTRACT FROM AUTHOR]

Based on the transport and polarization relaxation theories, the effects of hydrogen, fluorine, and chlorine atom passivation on the conductivity and dielectric properties of silicon carbide nanowires (SiCNWs) were numerically simulated. The results show that passivation can decrease the dark conductivity of SiCNWs and increase its ultraviolet photoconductivity. Among them, the photoconductivity of univalent (H) passivated SiCNWs is better than that of seven-valent (Cl, F) passivated SiCNWs. In terms of dielectric properties, the passivated SiCNWs exhibit a strong dielectric response in both deep ultraviolet and microwave regions. Hydrogen passivation SiCNWs produce the strongest dielectric response in deep ultraviolet, while fluorine passivation SiCNWs produce the strongest dielectric relaxation in the microwave band, which indicates that atomic passivation SiCNWs have a wide range of applications in ultraviolet optoelectronic devices and microwave absorption and shielding. [ABSTRACT FROM AUTHOR]

It is a formidable challenge to find the minority carrier recombination lifetime in low-dimensional devices as low-dimensionality increases the surface recombination rate and often reduces the recombination lifetime to a scale of picoseconds. In this work, we demonstrated a simple but powerful method to quantitatively probe the minority carrier recombination lifetime in silicon nanowires or microwires by fitting the experimental photoresponses with our recently established analytical photoresponse principle of photoconductors. The nanowires were passivated with small molecules and Al2O3 to suppress surface recombination, which will increase the minority recombination lifetimes. As expected, the minority carrier recombination lifetime found by this approach increases by orders of magnitude. These wires were also made into PIN diodes, the leakage of which was reduced at least 1 order of magnitude after surface passivation by Al2O3. The minority recombination lifetime found from the leakage current of these devices is largely consistent with what we found from our analytical photoresponse principle. As a further step, we performed scanning photocurrent microscopy to find the minority diffusion length from which we found that the minority recombination lifetime is close to what we found from the analytical photoresponses. In short, this work validated that our analytical response principle is a reliable method to find the minority recombination lifetime in low-dimensional semiconductors. [ABSTRACT FROM AUTHOR]

Fabrication of modern solid-state devices demands precise control of shape and dimensions, which requires an accurate knowledge of the role that surfaces play in such devices. To contribute to the understanding of surface effects on silicon nanowires, we present an atomistic study of the electronic properties of silicon nanostructures exhibiting surface facets over the (100) , (110) , (111) , and (112) crystallographic planes. We calculate the electronic structure of slabs in such a way that the effect of individual facets may be observed. Subsequently, we determine the electronic structure of nanowires grown along the [ 100 ] , [ 110 ] , [ 111 ] , and [ 112 ] directions, with surfaces defined by a combination of the mentioned facets. Our nanowires comprise diameters ranging from 1 to 6.7 nm and structures with more than 1000 atoms. We discuss the band structure, the relation between direct and indirect bandgaps, and the density of states. We base our calculations on semiempirical pseudopotentials where we implement complex potentials to describe passivants. We find that there is a transition from direct to indirect gap for the [ 111 ] direction at approximately 2 nm and that the difference between the direct and indirect gap may reach more than 300 meV depending on the diameter. We show that the occurrence of a direct bandgap is favored by the presence of the (100) facet and that it is related to a higher surface density of states. Conversely, we find that the (111) facet is the most inert surface type with a lower surface density of states. [ABSTRACT FROM AUTHOR]

InAs nanowires (NWs) were grown on SiOx pinholes formed on Si(111) substrates by molecular beam epitaxy. Influences of electron-beam (EB) irradiation on the SiOx layer on the pinhole formation and the subsequent InAs NW growth were studied. As the EB irradiation dose increased, the pinhole density in the SiOx layer decreased. From atomic force microscopy, transmission electron microscopy, and x-ray photoelectron spectroscopy results, it was found that the pinhole etching of the SiOx layer by Ga droplets was suppressed by carbon adsorption due to the EB irradiation. By forming high-density pinholes on the SiOx layer without the EB irradiation, high-density InAs NWs with 1–2 × 1010 cm−2 were grown successfully, and the uniformity in the NW diameter improved. The standard deviation of the NW diameter was 1.8 nm (8.8%) for high-density NWs. In addition, the NW diameter decreased with decreasing EB dose, and the NW diameter was controlled by adjusting the diameter of Ga droplets forming the pinholes. As the NW diameter decreased, photoluminescence spectra of the NWs shifted to higher energies than the bandgap energy of the wurtzite InAs bulk. From these results, we successfully fabricated high-density and high-uniformity InAs NWs with quantum size effects on EB-unirradiated SiOx/Si(111). [ABSTRACT FROM AUTHOR]

Using large scale molecular dynamics simulations, we study the thermal conductivity of bare and surface passivated silicon nanowires (SiNWs). For the cross–sectional widths w ⩽ 2 nm, SiNWs become unstable because of the surface amorphization and also due to the evaporation of a certain fraction of Si atoms. The observed surface (in–)stability is related to a large excess energy Δ of the surface Si atoms with respect to the bulk Si, resulting from the surface atoms being less coordinated and having dangling bonds. We first propose a practically relevant method that uses Δ as a guiding tool to passivate these dangling bonds with hydrogen or oxygen, stabilizing the SiNWs. These passivated SiNWs are used to calculate the thermal conductivity coefficient κ. While the expected trend of κ ∝ w is observed for all SiNWs, surface passivation provides an added flexibility of tuning κ with the surface coverage concentration c of passivated atoms. Indeed, with respect to the bulk κ, passivation of SiNW reduces κ by 75%–80% for c → 50 % and increases it by 50% for the fully passivated samples. Analyzing the phonon band structures via spectral energy density, we discuss separate contributions from the surface and the core to κ. Our results also reveal that surface passivation increases SiNW stiffness, contributing to the tunability in κ. [ABSTRACT FROM AUTHOR]

Water contamination due to significant industrialization and urbanization has drawn the attention of numerous researchers to water remediation techniques like photocatalysis. The intriguing characteristics of silicon nanowires (SiNWs), like light trapping and catalytic activity for the removal of textile dyes, have drawn attention to this material. In this work, the synthesis of SiNWs and their modifications with metal particles like copper or silver with different concentrations has been reported. Metal‐assisted chemical etching, a cost‐effective and easy method, is used to synthesis SiNWs with an optimized aspect ratio. The as‐prepared materials and it photocatalysis performance are studied by X‐ray diffraction (XRD), field emission and transmission electron microscope (FESEM, TEM), and UV–visible spectroscopy. The XRD confirms the presence of the copper particles on SiNWs. The FESEM image reveals the formation of flower‐like structures with different morphologies for silver and copper‐modified SiNWs. The as‐prepared samples have shown efficacy in removing Rhodamine‐B by the process of photocatalysis under irradiation with UV light. It has been observed that when the concentration of the copper nanoparticles is increased, a significant increase in the photocatalytic activity is obtained. The removal efficiency came within the range of 50–65%. [ABSTRACT FROM AUTHOR]

For the preparation of SiC nanowires (SiC NWs) by carbothermal reduction, it is of great significance to study the formation mechanism of sic nanowires for process optimization and the controllable preparation. Although first-principles molecular dynamics (FPMD) can simulate systems of hundreds of atoms on a picosecond time scale, the results of FPMD are still insufficient to elucidate the formation mechanism of core-shell SiC nanowires. To make up this deficiency, this article has conducted Deep Potential Molecular Dynamics (DPMD) simulation on nanoseconds timescales with near FPMD accuracy for systems containing thousands of atoms, the results more concretively show the formation process of core-shell SiC nanowires. DPMD simulation results show when CO molecules react with SiO molecules, CO molecules are wrapped by SiO molecules to form agglomerates, SiO molecules in the agglomerates that can come into contact with the wrapped CO molecules will react with wrapped CO molecules to form the SiC core, and SiO molecules that in the outer layer of the agglomerates will disproportionate into the amorphous SiO 2 shell. Furthermore, the formation mechanism of SiC nanowires was validated in combination with thermodynamics and experimental methods. Thermodynamic results show that vacuum conditions are favorable for the formation of SiO and CO and lower the temperature of SiC preparation. Finally, the core-shell structure of SiC NWs with good luminescence properties were successfully prepared by carbothermal reduction method using carbon black and silicon dioxide as raw materials under the pressure of less than 5 kPa. [ABSTRACT FROM AUTHOR]

Stacking faults (SFs) could be generated in aluminum (Al) via full dislocations extension under extreme stress. However, the extension behavior of the dislocations related to the stress conditions have not been studied comprehensively. In this study, SFs were generated solely under extreme stress condition in coarse–grained Al nanocomposites, where high content of Silicon Carbide nanowires (SiCnw) was introduced as reinforcement. Dislocation extension behaviors under normal and shear stress were predicted using an atomistic approach comparing with experiment methods. The extension ability of full dislocations was studied in terms of complex stress forced on partial dislocations and the relationship between stress condition and the SF width was established by stress analysis. The generated SFs were further proved to offer superb additional strengthening effect for the composites. This study provides a new idea and theory for designing of SF generation in coarse–grained Al based nanocomposites. [ABSTRACT FROM AUTHOR]

In GaN‐on‐Si nanowire integration schemes, where the nanowires are contacted through the substrate, the interfaces between silicon substrate, AlN buffer layer, and GaN nanowire are of high interest. Herein, analysis by scanning transmission electron microscopy (STEM) of GaN nanowires grown on Si(111) by metal–organic vapor phase epitaxy using a polarity‐ and site‐controlled growth method is presented. This method is based on prestructuring the substrate, ex situ oxidation of the surface, and in situ oxide layer desorption. First, an AlN layer is grown to prevent melt‐back etching. Samples are prepared for STEM by focused ion beam cutting. STEM measurements in three different regions reveal that the AlN buffer material is polycrystalline. The degree of polycrystallinity is found to depend on the observed region: the highest degree exists at the field area between nanowires and the lowest at the sidewall of the Si‐pillars. On the sidewall, the c→$$ \overrightarrow{c} $$‐direction of the AlN grain is tilted by 30.1° with regard to the Si{111} sidewall plane, leading to reduced lattice mismatch at this location. The growth of GaN is competing with diffusion of Ga atoms through grain boundaries. The dominant mechanism is dependent on the region, leading to site‐controlled growth of nanowires. [ABSTRACT FROM AUTHOR]

A significant (up to 4 times) photoluminescence enhancement of single InP/InAsP/InP nanowires transferred onto a silicon oxide‐covered silver layer on silicon substrate with a metal surface roughness level of less than 1 nm and a dielectric thickness of 5 nm has been demonstrated. This phenomenon is explained by the interaction of electron–hole pairs in the semiconductor with surface plasmon polaritons. The photoluminescence kinetics and results of modeling confirm the indicated enhancement mechanism. [ABSTRACT FROM AUTHOR]

This study employed a computational approach, particularly Density Functional Theory at B3LYP−D3/6‐31+G(d) level to design two new classes of three‐dimensional (3D) Lantern Organic Frameworks (LOFs) materials based on trisilasumanene and porphyrin core building units. Particularly, we detail strategies for transitioning from 1D‐LOF nanowires to extended 3D structures: first by connecting planar‐molecule base units of trisilasumanene or porphyrin using benzene‐based linkers, and then connecting silicon anchoring atoms on the bases with other bases that are vertically stacked by sp3‐hydrocarbon chains. The 3D‐LOF structures are designed to have different pore sizes through the use of various bases, bridges, and linkers. Comparisons of electronic properties of these 3D structures lead to one designing rule. That is, the gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the 3D materials depends only on its base and is nearly independent of the stack size or the length of the sp3‐hydrocarbon bridges. Additionally, connecting base units with linkers also extends π‐electron conjugation system leading to a reduction in HOMO‐LUMO gap. For instance, linking two trisilasumanene molecules significantly narrows HOMO‐LUMO gap by 1.75 eV while stacking these bases vertically and connecting them by linear pentane‐based bridges yield insignificant change to the gap. [ABSTRACT FROM AUTHOR]

Light polarization control is a target in photonics, and this paper provides a comprehensive review of research from various groups on the silicon‐on‐insulator (SOI) platform. It draws comparisons between devices such as polarization splitters (PS), polarizers, and polarization splitters/rotators (PSR). These devices are fabricated using various technologies, including silicon nanowires, ridge waveguides, hybrid plasmonic waveguides, and subwavelength grating (SWG) waveguides. A detailed review of polarizers used as cleanup filters in splitters is initiated. Subsequently, various polarization splitters utilizing asymmetric directional couplers (ADCs), which typically exhibiting low extinction ratios (ERs), are delved. To enhance ERs, a detailed comparison of methods outlined in the literature is provided. One notable method includes integrating on‐chip polarizers at both ports to eliminate unwanted light fractions and achieve exceptionally high ERs. Furthermore, SWG‐based polarizers and splitters commonly face issues with Bragg reflections that can affect other photonic devices and lasers and ways to minimize unwanted polarization back reflections in SWG‐designed polarization control devices are examined. Finally, emerging applications in mid‐infrared (MIR) sensing are explored, highlighting the necessity of polarization rotators for on‐chip transverse electric (TE) operation, since quantum cascade lasers, the primary sources in this range, emitting radiation in the (TM) mode. [ABSTRACT FROM AUTHOR]

This study reports the findings from an investigation into charge carrier transport within a silicon nanowire layer. The samples were prepared using the metal-assisted chemical etching method applied to crystalline silicon wafers with a resistance of 10–20 Ω·cm. The resulting silicon nanowires had a diameter of about 100 nm with a resistance of approximately 15 kΩ·cm. Electrical conductivity measurements were performed in both planar and sandwich configurations, revealing analogous conductivity mechanisms across different geometries. Frequency-dependent conductivity studies unveiled the presence of hopping conductivity. A hypothesis is proposed regarding the existence of a potential barrier at the interface between the nanowire layer and the substrate. [ABSTRACT FROM AUTHOR]

Metallic nanowires, particularly polyol-grown silver nanowires, exhibit a morphological instability at temperatures significantly lower than their bulk melting point. This instability is commonly named after Rayleigh's description of the morphological instability of liquid jets, even though it has been shown that its quantitative predictions are not consistent with experimental measurements. In 1996, McCallum et al. proposed a description of the phenomenon assuming a solid wire lying on a substrate. It is assumed that the latter description depicts more accurately the reality. Nanowires with varying diameters have been deposited on silicon wafers. Statistical analysis of their radius and the wavelength of their periodical instability have been performed. McCallum et al.'s model better aligns with experimental observations compared to Rayleigh's description. This validation provides a robust theoretical framework for enhancing the stability of nanowires, addressing a crucial aspect of their development. [ABSTRACT FROM AUTHOR]

Silicon, with its many advantages, is gaining attention in the field of lithium-ion battery anode materials. However, severe volume swelling, poor conductivity, and slow Li+ diffusion kinetics are major obstacles to enhancing the electrochemical properties of silicon anodes. One-dimensional silicon nanowires with a high aspect ratio can effectively ameliorate these issues, while the complexity of the synthesis method limits its development. Here, a three-dimensional flexible electrode of binary-phase Ni-silicide foam loaded with silicon nanowires (NixSiy@Si NWs) was constructed in two simple steps: preparation of metal catalyst nanoparticles using a chemical plating approach and production of silicon nanowires by the supercritical fluid-liquid–solid mechanism. Benefiting from the excellent anchoring ability and superior electrical conductivity of NixSiy as well as the extra space and favorable Li+ and electrolyte diffusion paths provided by the Si NWs network, the as-obtained anode exhibits a high initial Coulombic efficiency of 77% at 0.5 A g−1, excellent cycling performance (a reversible capacity of 1238 mAh g−1 after 200 cycles) and outstanding rate capability (2675, 2497, 2164, 1740, and 1222 mAh g−1 at 0.5, 1, 2, 4, and 8 A g−1, respectively). [ABSTRACT FROM AUTHOR]

Nanostructured silicon solar cells are designed to minimize costs through reduced material usage while enhancing power conversion efficiency via superior light trapping and shorter charge separation distances compared to traditional planar cells. This study identifies the optimal conditions for nanoimprinted silicon nanowire (SiNW) solar cells to achieve maximum efficiency under low sunlight concentration and evaluates their performance as bottom cells in III-V multijunction solar cell systems. The findings indicate that the SiNW solar cell reaches its peak performance at a concentration factor of 7.5 suns and a temperature of 40°C or lower. Specifically, the absolute conversion efficiency under these conditions is 1.05% higher than that under unconcentrated light. Compared to a planar silicon solar cell under identical conditions, the SiNW solar cell exhibits a 3.75% increase in conversion efficiency. Additionally, the SiNW single-junction solar cell, when integrated in series with a commercial latticematched InGaP/GaAs dual-junction solar cell, was tested under unconcentrated sunlight, specifically at one-sun, global air mass 1.5 condition, to assess its viability in one-sun multi-junction solar cell applications. The results suggest that a III-V upper subcell with a smaller active area than that of the SiNW subcell is optimal for maximizing current production, which is favorable to the cost reduction of the device. This hybrid configuration is particularly advantageous for terrestrial applications, such as electric vehicles, which demand lightweight, highperformance multijunction solar cell devices. Although the weight reduction of the characterized SiNW solar cell with a full silicon substrate compared to its planar solar cell counterpart is 1.8%, recommendations to increase this reduction to as much as 64.5% are discussed to conclude this paper. [ABSTRACT FROM AUTHOR]

Recently it is shown that sensitivity of biosensors can be considerably improved using single trap phenomena resulting in two‐level random telegraph signal (RTS) switching in current. To develop the transistor structure with a predefined trap position using gold antenna is suggested, which can be excited by light of different intensities to influence the properties of the underlying dielectric layer. High‐quality liquid gate‐all‐around (LGAA) silicon nanowire (NW) field‐effect transistor (FET) biosensors are fabricated with a gold bowtie antenna. The transport and noise properties of these new NW FETs are investigated at 940 nm LED excitation in a 1 mm phosphate‐buffered saline (PBS) solution with pH = 7.4. A strong sensitivity of I–V and noise characteristics is revealed with an increase in LED intensity. Well‐resolved Lorentzian components are only found under the influence of light excitation. A two‐level RTS is successfully excited with linear dependence of its amplitude versus intensity. In addition, repeatable fluctuations in current are resolved as small peaks in I–V curves under infrared illumination, thus confirming the excitation of a two‐level RTS in the biosensors. The results demonstrate that the FET devices with a gold antenna have significant potential for the excitation of two‐level signals to enhance the sensitivity of biosensors. [ABSTRACT FROM AUTHOR]

Highlights: A new strategy for elaborate regulation of microstructure was successfully introduced by the ice template‑assisted 3D printing and chemical vapor deposition strategy, including graphene nanoplate/silicon carbide nanowires hierarchical porous structure and graphene nanoplate/boron nitride composite heterogeneous interface. The composite exhibits excellent electromagnetic wave absorption performance with an RLmin of -37.8 dB and an EABmax of 9.2 GHz (from 8.8 to 18.0 GHz) at 2.5 mm. And the high-temperature absorption stability makes it a promising absorber candidate under high temperature and oxidizing atmosphere. With vigorous developments in nanotechnology, the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers. Herein, a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity. The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires (SiCnws) grown in situ, while boron nitride (BN) interfacial structure is introduced on graphene nanoplates. The unique composite structure forces multiple scattering of incident EMWs, ensuring the combined effects of interfacial polarization, conduction networks, and magnetic-dielectric synergy. Therefore, the as-prepared composites present a minimum reflection loss value of − 37.8 dB and a wide effective absorption bandwidth (EAB) of 9.2 GHz (from 8.8 to 18.0 GHz) at 2.5 mm. Besides, relying on the intrinsic high-temperature resistance of SiCnws and BN, the EAB also remains above 5.0 GHz after annealing in air environment at 600 °C for 10 h. [ABSTRACT FROM AUTHOR]

Thermal management becomes increasingly important in silicon gate‐all‐around (GAA) field‐effect transistor (FETs) for 3 nm technology node and beyond. The channel thermal conductivity significantly differs from bulk silicon. Precise determination of thermal conductivity is crucial for device evaluation and optimization. This study investigates the thermal conductivity of silicon nanowires, examining the complex interplay between size and channel orientation. The conventional nonequilibrium molecular dynamics (NEMD) method is used with the standard Stillinger–Weber potential at the atomic scale. The results indicate that the thermal conductivity of silicon nanowires along the [100] direction increases monotonically with both length (L) and cross‐sectional side length (D). Conversely, the [110] direction exhibits nonmonotonic variation in thermal conductivity with D, due to increased acoustic–optic phonon scattering. For GAA FET devices with a silicon nanowire channel of L = 20 nm and D = 5 nm, the NEMD calculations yield thermal conductivities of 10.8 W m·K−1 for the [100] direction and 25.3 W m·K−1 for the [110] direction. Subsequently, the self‐heating effect (SHE) in silicon nanowire GAA FETs by technology computer‐aided design with the modified channel conductivity is analyzed. The results suggest that silicon nanowires with the [110] transport direction are more suitable for device design. [ABSTRACT FROM AUTHOR]

Dielectric elastomers (DEs), have attracted interest because they can replicate the behavior of muscles. They can change shape when subjected to an electric field. A novel DE is proposed in this study that incorporates silicon carbide (SiC) nanowires into silicone rubber (SR). The nanowires were propagated using polycarbosilane via a chemical vapor reaction (CVR). A boronate polymer was employed to promote compatibility between SR and SiC nanowires which modified the nanowire surfaces, leveraging a strong adhesive quality of the catechol moiety. Electrohydrodynamic (EHD) inkjet printing was then used to form the DEs into various shapes. These DEs had substantial dielectric constants of the order of 4.46. Significantly, one of the DEs achieved the highest actuated area strain of 20.36% in an electric field of 16.5 V/μm, demonstrating excellent driving performance. Furthermore, when used the fabricated DEs showed pronounced long‐term stability, meaning they are capable of finding applications in artificial intelligence, biomimetics, aerospace, and other disciplines. Highlights: The SiC nanowires were obtained through a chemical vapor reaction.A boronate polymer with catechol moiety was used to modify the SiC nanowires.DEs were formed various shapes by inkjet printing.DEs achieved very large actuated strains of up to 20.36% at 16.5 V/μm. [ABSTRACT FROM AUTHOR]

Surface‐assisted laser desorption/ionization (SALDI) mass spectrometry imaging (MSI) holds great value in spatial metabolomics and tumor diagnosis. Tissue imprinting on the SALDI target can avoid laser‐induced tissue ablation and simplifies the sample preparation. However, the tissue imprinting process always causes lateral diffusion of biomolecules, thereby losing the fidelity of metabolite distribution on tissue. Herein, a membrane‐mediated imprinting mass spectrometry imaging (MMI‐MSI) strategy is proposed using isoporous nuclepore track‐etched membrane as a mediating imprinting layer to selectively transport metabolites through uniform and vertical pores onto silicon nanowires (SiNWs) array. Compared with conventional direct imprinting technique, MMI‐MSI can not only exclude the adsorption of large biomolecules but also avoid the lateral diffusion of metabolites. The whole time for MMI‐based sample preparation can be reduced to 2 min, and the lipid peak number can increase from 46 to 113 in kidney tissue detection. Meanwhile, higher resolution of MSI can be achieved due to the confinement effect of the pore channel in the diffusion of metabolites. Based on MMI‐MSI, the tumor margins of liver cancer can be clearly discriminated and their different subtypes can be precisely classified. This work demonstrates MMI‐MSI is a rapid, highly sensitive, robust and high‐resolution technique for spatially‐resolved metabolomics and pathological diagnosis. [ABSTRACT FROM AUTHOR]

Interband cascade lasers typically have significantly lower threshold current and power consumption than quantum cascade lasers. They can also have advantages regarding costs and compactness with the photonic integration onto silicon substrates by epitaxial growth. This research introduces a novel examination of the relative intensity noise and the modulation dynamics of a silicon-based Fabry–Perot interband cascade laser emitting at 3.5 μm. The investigation delves into crucial parameters, such as relaxation oscillation frequency, differential gain, gain compression, and K-factor. The resonance patterns identified in relative intensity noise curves can provide essential insights for the thorough characterization of high-defect mid-infrared semiconductor structures intended for high-speed applications. Moreover, this study demonstrates the feasibility of reaching 10 Gbit/s free-space transmission using a silicon-based interband cascade laser in conjunction with an interband cascade infrared photodetector. [ABSTRACT FROM AUTHOR]

In this article, we propose a novel natural light detector based on high-performance silicon nanowire (SiNW) arrays. We achieved a highly controllable and low-cost fabrication of SiNW natural light detectors by using only a conventional micromachined CMOS process. The high activity of SiNWs leads to the poor long-term stability of the SiNW device, and for this reason, we have designed a fully wrapped structure for SiNWs. SiNWs are wrapped in transparent silicon nitride and silicon oxide films, which greatly improves the long-term stability of the detector; at the same time, this structure protects the SiNWs from breakage. In addition, the SiNW arrays are regularly distributed on the top of the detector, which can quickly respond to natural light. The response time of the detector is about 0.015 s. Under the illumination of 1 W·m−2 light intensity, multiple SiNWs were detected together. The signal strength of the detector reached 1.82 μA, the signal-to-noise ratio was 47.6 dB, and the power consumption was only 0.91 μW. The high-intensity and highly reliable initial signal reduces the cost and complexity of the backend signal processing circuit. A low-cost and high-performance STM32 microcontroller can realize the signal processing task. Therefore, we built a high-performance SiNW natural optoelectronic detection system based on an STM32 microcontroller, which achieved the real-time detection of natural light intensity, with an accuracy of ±0.1 W·m−2. These excellent test performances indicate that the SiNW array natural light detector in this article meey the requirements of practicality and has broad potential for application. [ABSTRACT FROM AUTHOR]

Silicon monoxide nanowires have become ubiquitous in twenty-first century technology due to their superior photoelectric properties, widely utilized in semiconductor manufacturing and emerging energy fields. While numerous studies have concentrated on tailoring material properties, scant attention has been paid to the impact of process parameters on the productivity of silicon monoxide during synthesis. Through response surface methodology, the effects of holding time, heating temperature, and Si/SiO2 molar ratio on the volatilization ratio of silicon monoxide have been investigated. The optimization of silicon monoxide nanowire preparation via vacuum silicothermic reduction was aimed at achieving maximum efficiency. According to the established mathematical model, the volatilization ratio of silicon monoxide reaches 92.057% when the holding time is 126 min, the heating temperature is 1663 K, and the molar ratio is 1. A comprehensive analysis revealed that temperature is the most significant factor affecting silicon monoxide volatilization among the studied parameters. Furthermore, the reduction slag of the system was characterized and analyzed. The results indicate that vacuum conditions can lower the starting temperature of the silicothermic reduction, thereby promoting the volatilization of SiO(g). [ABSTRACT FROM AUTHOR]

This paper presents an integrated approach for a retinal prosthesis that overcomes the scalability challenges and limitations of conventional systems that use external cameras. Silicon nanowires (SiNWs) are utilized as photonic sensors due to their nanoscale dimensions and high surface-to-volume ratio. To enhance these properties and achieve high photoresponsivity, our research team developed a vertically stacked SiNW structure using a fabrication method entirely based on dry etching. The fabricated SiNW photodetector demonstrated excellent electrical and optical characteristics, including linear I–V characteristics that confirmed ohmic contact formation and high photoresponsivity exceeding 105 A/W across the 400–800 nm wavelength range. The SiNW photodetector, following its integration with a switched capacitor stimulator circuit, exhibited a proportional increase in stimulation current in response to higher light intensity and increased SiNW density. In vitro experiments confirmed the efficacy of the integrated system in inducing neural responses from retinal cells, as indicated by an increased number of neural spikes observed at higher light intensities and SiNW densities. This study contributes to sensor technology by demonstrating an approach to integrating nanostructures and electronic components, which enhances control and functionality. [ABSTRACT FROM AUTHOR]

The development of electrodes for hydrogen evolution via water splitting in a neutral electrolyte is highly desirable, especially considering that natural water resources such as seawater typically have a neutral pH. In this study, silicon nanowires (SiNWs) arrays with uniform silver (Ag) decoration are prepared as a cathode material, which exhibits excellent and stable electrochemical performance for neutral water electrolysis. Ag ions, utilized in the preparation of SiNWs through metal-assisted chemical etching technique, are retained and decorated within the SiNWs array without undergoing a dissolution process, referred to as Native SiNWs. Remained Ag+ ions on the SiNWs are activated photocathodically and reduced to Ag0, resulting in a significantly enhanced performance as an electrocatalyst for hydrogen evolution reaction (HER). Hence, this photocathodic activation of Native SiNWs (PCA-Native SiNWs) eliminates the need for additional cocatalyst deposition for HER, utilizing the Ag ions employed in the SiNWs preparation process. This enhancement in HER activity is exclusively observed by photocathodic activation, not by cathodic activation without light irradiation, indicating the crucial role of photoelectrons in SiNWs under light irradiation for the activation. Additionally, the nanowire structure serves as an ideal platform for Ag nanoparticles, providing sufficient surface area, resulting in excellent dispersion and an increased number of active sites. Furthermore, PCA-Native SiNWs demonstrates outstanding electrochemical stability for over 60 h, with no significant reduction in current density or structural degradation in a neutral electrolyte. Several characterizations and electrochemical analyses have been conducted to elucidate the in-situ decoration of Ag nanoparticles on SiNWs and investigate the surface chemistry for the activation mechanism. This work introduces a new perspective on using Ag-decorated SiNWs directly as an electrocatalyst for effective hydrogen evolution in a neutral media. Saleem et al., "A Strategy to Reutilize Silver Nanoparticles on Silicon Nanowires via Photocathodic Activation for Enhanced and Sustainable Hydrogen Evolution"Native SiNWs, which are prepared by retaining Ag nanoparticles during SiNW synthesis, exhibited better performance for HER than SiNWs. Additionally, the retained Ag can be more evenly distributed and reduced during photocathodic activation, resulting in significantly improved HER activity. [Display omitted] • Photocathodically activated Native SiNWs (PCA-Native SiNWs) are developed. • Retained Ag ions on SiNWs are reduced and activated by light irradiation and cathodic potential (photocathodic activation). • Reduced Ag enhances electrochemical performance of SiNWs as an electrocatalyst. • Ag nanoparticles are evenly distributed vis the dissolution-redeposition phenomenon. • PCA-Native SiNWs show stable activity in neutral pH. [ABSTRACT FROM AUTHOR]

A Schottky barrier tunneling field-effect transistor (SBT FET) built upon catalytically grown ultrathin silicon nanowires (SiNWs) offers a preferable low-temperature routine to construct top device layers for monolithic three-dimensional (3D) integration technology, but there still remain several peculiar electronic transport behaviors that need to be better understood. In this work, a high-performance SBT FET was fabricated based on orderly SiNWs grown via the in-plane solid–liquid–solid (IPSLSL) mechanism, achieving an Ion/Ioff ratio of 106 and a SS of 150 mV/dec. The as-fabricated device, with SBT contacts between SiNWs and Pt/Au source-drain electrodes, was analyzed and compared to a three-dimensional numerical model built via the TCAD simulator to extract the actual energy band profile and the bias distribution in the SBT FET, as well as the hole carrier mobility in the catalytic SiNW channels. This comparative investigation also reveals the limiting factors for the SBT transport and explains well the observed peculiar channel-bias-dependent drain-induced barrier-lowering (DIBL) behavior. These results provide an in-depth understanding of SBT FET and lay a solid basis for its future applications in high-performance logic and in-memory computing in advanced 3D architecture. [ABSTRACT FROM AUTHOR]

Direct bandgap group IV semiconductors, like strained Ge, GeSn, or hexagonal SiGe, are considered promising for photonic integration on silicon. For group IV semiconductor lasers, it is crucial to understand the carrier cooling efficiency toward the band edges. From a fundamental perspective, a study of carrier cooling within the Γ-valley of direct bandgap group IV semiconductors is particularly interesting since the Fröhlich interaction is expected to be very weak or even absent in these materials due to the nonpolar lattice. Intravalley carrier relaxation within the Γ-valley of a nonpolar semiconductor has not been experimentally accessible before since it has always been overshadowed by intervalley processes between energetically close indirect conduction band minima. Here, we study carrier cooling in direct bandgap hexagonal silicon-germanium (hex-SiGe) nanowires, allowing us to study carrier cooling in an isolated Γ-valley that is sufficiently separated from the indirect minima. We obtain a hot carrier cooling time of 180 ps in the Γ-valley of hex-SiGe. Although the cooling is much slower than in bulk polar group III/V materials due to the absence of Fröhlich interaction, it is comparable to the cooling time in an InGaAs MQW laser structure. We conclude that carrier cooling does not inherently limit hex-SiGe to serve as a laser gain material. This result is an important insight into the field of group IV semiconductor lasers. [ABSTRACT FROM AUTHOR]

Silicon (Si) is a promising anode material for high‐energy‐density lithium‐ion batteries. To achieve wide practical applications, it is highly desirable to build effective solidelectrolyte interphase (SEI) with high stability and high Li+ conductivity. Herein, a novel interface engineering strategy is demonstrated with the assistance of a surfactant and the self‐assembly of chitosan (CS) skin on Si surface. A high coating integrity of the Si particle is obtained compared to that without surfactants. Unlike traditional surface coatings, the positive charge of the applied CS layer enables it to selectively absorb PF6− anions in the electrolyte. The PF6− aggregates in Helmholtz layer lead to the formation of anion‐derived SEI enriched in LiF species. As the result, the prepared CS‐decorated Si anode exhibits a high initial coulombic efficiency of 92.2% and a high rate capability of 2200 mAh g−1 capacity at 10 C rate. After 500 charge–discharge cycles, it is still able to retain a reversible capacity 1621.3 mAh g−1. Furthermore, the excellent electrochemical property is demonstrated in full cells against NCM811 cathode. The novel interface engineering strategy provides a new SEI mechanism and demonstrates a feasible and effective way to develop high‐performance Si‐based lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

In this study, we successfully synthesized silicon nanotubes (Si-NTs) and silicon nanowires (Si-NWs) in a controllable manner using a catalyst- and template-free method through the direct electrolysis of SiO2 in a molten CaCl2-CaO system, while also proposing a novel formation mechanism for Si-NTs. Si-NWs are formed through electro-deoxidation when the cell voltage is within the range of CaO decomposition voltage and SiO2 decomposition voltage. By subsequently adjusting the voltage to a value between the decomposition potentials of CaCl2 and CaO, in-situ electro-deoxidation of CaO takes place on the surface of the synthesized Si-NWs, leading to the formation of a Ca layer. The formation of Ca-Si diffusion couple leads to the creation of vacancies within the Si-NWs, as the outward diffusion rate of Si exceeds the inward diffusion rate of Ca. These differential diffusion rates between Si and Ca in a diffusion couple exhibit an analogy to the Kirkendall effect. These vacancies gradually accumulate and merge, forming large voids, which ultimately result in the formation of hollow SiCa-NTs. Through a subsequent dealloying process, the removal of the embedded calcium leads to the formation of Si-NTs. Following the application of a carbon coating, the Si-NTs@C composite showcases a high initial discharge capacity of 3211 mAh·g−1 at 1.5 A·g−1 and exhibits exceptional long-term cycling stability, maintaining a capacity of 977 mAh·g−1 after 2000 cycles at 3.0 A·g−1. [ABSTRACT FROM AUTHOR]

Silicon is the most diffused material in the industry; thus, considering its high capacity for energy storage, silicon‐based materials are well studied as battery anodes and supercapacitors. Si nanowires (NWs) emerge due to the high surface to volume ratio, its compatibility with a wafer processing typical of microelectronics, and are studied as anodes for lithium batteries as well as coupled with other materials for supercapacitor application. In this article, the synthesis and application are reported as a lithium anode of 2D fractal arrays of ultrathin Si NWs obtained by a thin‐film metal‐assisted chemical etching (MACE). These Si NWs exhibit a density of about 1012 NWs cm−2, maximizing the surface to volume ratio compared to silver‐salts MACE and other NW fabrication approaches. By using 2.7 μm long NWs, a pseudo‐capacitor behavior with a specific capacitance of about 274.2 μF cm−2 at a scan rate of 50 mV s−1 is obtained. This specific capacitance is two orders of magnitude higher than the one obtained in the same condition by using NWs synthesized by silver‐salt MACE. In this result, the route is opened toward the application of these fractal arrays of ultrathin Si NWs as substrate for supercapacitors with improved efficiency. [ABSTRACT FROM AUTHOR]

Epitaxial BaTiO3 integrated on Si or Si-on-insulator using off-axis radio frequency sputtering is a promising material platform for building electro-optic modulators based on the Pockels effect. Barium titanate thin films with c-axis orientation have been epitaxially integrated on silicon-on-insulator wafers. They exhibit excellent structural quality with Pockels coefficient (r33) > 130 pm/V and propagation loss <2 dB/cm. Our results show that off-axis sputtered BaTiO3 films yield electro-optic modulation similar to that of high-quality films grown by molecular beam epitaxy and that the material is suitable for implementation of low-power Mach–Zehnder interferometer electro-optic modulators integrated on silicon in a Z-cut configuration. [ABSTRACT FROM AUTHOR]

Semiconductor industry is experiencing unprecedented growth, still driven by Moore's law, which is continually delivering devices with improved performance at lower costs. The continuation of this development places the industry in a divergent trade-off between economic attractiveness, technological feasibility, and the need for further performance improvement. Since the mainstream semiconductor technologies are silicon-based, new disruptive innovations are needed to gain additional performance margins. The use of nanowires is the preferred approach for preserving electrostatic control in the MOS transistor channel, and the application of mechanical stress is a booster of carrier mobility. It is in this context that this paper presents the design, fabrication, theoretical modeling, and characterization of a measurement platform to characterize the mechanical tensile stress of extremely narrow Si nanowires as small as 14.2 ± 1.12 nm in width. The proposed measurement platform enables a precise control of uniaxial strain, in terms of both amplitude and location, through the implementation of a stoichiometric Si3N4 pulling strand exerting a high tensile force on silicon nanowires. Reported devices are fabricated using a silicon-on-insulator wafer with fully complementary metal–oxide–semiconductor-compatible processing and top-down approach. It is observed that the mechanical strength of nanostructured Si is size-dependent and increases with miniaturization. Characterization revealed a record tensile strength value of 7.53 ± 0.8% (12.73 ± 1.35 GPa) for the narrowest nanowires fabricated using a top-down approach. [ABSTRACT FROM AUTHOR]

Si 3 N 4 and SPEEK were simply mixed and used to prepare a Si 3 N 4 /SPEEK composite separator through electrospinning. The silicon nanowires formed at the interface between the Si 3 N 4 /SPEEK separator and the lithium anode result in the separator showing superior long-cycle performance. [Display omitted] • The Si 3 N 4 /SPEEK composite separator was prepared by electrospinning. • Si 3 N 4 in the Si 3 N 4 /SPEEK separator can be reduced by Li+ to form Si nanowires. • The Si 3 N 4 /SPEEK separator features a high specific surface area and abundant mesopores. • DFT calculations reveal that Si 3 N 4 has strong interactions with electrolyte molecules (EC and DMC). • Si 3 N 4 enhances the dimensional stability of separator at high temperatures and pressures. The uncontrolled lithium (Li) dendrite growth significantly impacts the safety performance of polymer separators. To mitigate this growth, this study introduces Si 3 N 4 into sulfonated poly(ether Ether Ketone) (SPEEK) and prepares Si 3 N 4 /SPEEK composite separators via electrospinning. At the interface between the Si 3 N 4 /SPEEK separator and the Li anode, the Si nanowires that form impede Li dendrite growth, thereby enhancing the electrochemical performance of lithium-ion batteries (LIBs). The Li deposition test of the 10 % Si 3 N 4 /SPEEK separator can operate for 1000 h without short-circuiting. Additionally, the LiFePO 4 ||Li cell with the 10 % Si 3 N 4 /SPEEK separator shows improved initial discharge capacity (157.8 mAh g−1 at 1C) and superior rate performance (125 mAh g−1 at 10C). Moreover, the nano-scale Si 3 N 4 endows the separator with robust thermal and mechanical properties. The FLIR observations reveal that the 10 % Si 3 N 4 /SPEEK separator maintains uniform thermal distribution and structural integrity even at 300 °C, ensuring safe battery operation at high temperatures. The additional load of the 10 % Si 3 N 4 /SPEEK separator can reach 10.2 mN, which enhances the puncture resistance of the separator. This work provides a solid approach for the application of SPEEK as a high-safety and high-rate LIB separator. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Photocatalysis is a promising green approach for water purification. The diversity of water pH values is a key factor that restricts its practical application since pH affects the adsorption of organic molecules, the stability of catalysts and photocatalytic performance. Here, we report a pH–independent, efficient and stable photocatalytic system with a liquid (water)–liquid (oil)–solid (semiconductor) (L–L–S) triphase interface microenvironment. The system is fabricated by coating a thin layer of silicon oil on the surface of ZnO nanowire arrays, a model chemically unstable semiconductor in both acidic and alkaline solutions. We show that the unique interface makes the dye adsorption pH independent and prevents the semiconductor from being corroded by strong acidic/alkaline solutions, leading to a stable and efficient photocatalytic reaction over a wide pH range (1—14). These findings reveal a promising path for the development of high‐performance catalysis systems applicable in complex water environments. [ABSTRACT FROM AUTHOR]

In this paper, Zinc Oxide nanoparticles (ZnO NPs) have been successfully synthesized for the first time by electrochemical deposition on silicon nanowires (SiNWs) produced using silver-assisted chemical etching method. The as-prepared nanowires were pre-coated with ZnO seed layer to initialize the uniform growth of ZnO nanoparticles from aqueous solutions using the electrochemical deposition. The SEM images showed a homogenous distribution of dense ZnO nanoparticles on silicon nanowires. X-ray diffraction pattern indicated that the electrodeposited ZnO NPs have hexagonal wurtzite structure. Current–voltage characteristics pointed that ZnO NPs significantly improved the diode parameters such as ideality factor (n), series resistance ( R s ), energy barrier ( φ b ) and saturation current ( I s ). As a result, a rectifying behavior of the ZnO NPs/SiNWs structure has been exhibited by a factor of 2.7 compared to pure SiNWs structures. The values of the saturation current I s and the series resistance R s of these heterostructures decrease indicating an improvement in junction quality which can be due to the reduction of dangling bonds and surface defects. Significantly, ZnO nanoparticles @SiNWs increased the minority carrier lifetime from 9.11 μ s to 14.89 μ s and consequently reduced the surface recombination activities, further revealing the efficient surface passivation role of ZnO nanoparticles. Good anti-reflectance abilities up to 10% and 15% are observed for pure SiNWs and SiNWs/ZnO NPs, respectively, as compared to 40% for bare Silicon. Based on these findings, SiNWs/ZnO NPs can be considered as potential candidate for optoelectronic devices, photovoltaics and nanoelectronics. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Photocatalysis is a promising green approach for water purification. The diversity of water pH values is a key factor that restricts its practical application since pH affects the adsorption of organic molecules, the stability of catalysts and photocatalytic performance. Here, we report a pH–independent, efficient and stable photocatalytic system with a liquid (water)–liquid (oil)–solid (semiconductor) (L–L–S) triphase interface microenvironment. The system is fabricated by coating a thin layer of silicon oil on the surface of ZnO nanowire arrays, a model chemically unstable semiconductor in both acidic and alkaline solutions. We show that the unique interface makes the dye adsorption pH independent and prevents the semiconductor from being corroded by strong acidic/alkaline solutions, leading to a stable and efficient photocatalytic reaction over a wide pH range (1—14). These findings reveal a promising path for the development of high‐performance catalysis systems applicable in complex water environments. [ABSTRACT FROM AUTHOR]

Changes in the interfacial structures of the amorphous silicon (a-Si) anode/organic electrolyte interfaces in lithium-ion batteries were investigated using highly dense a-Si films fabricated by cathodic arc plasma deposition as a model electrode. Raman spectroscopy, transmission electron microscopy (TEM), and X-ray reflectivity revealed that the Si films were grown in an amorphous state with an atomically flat surface. The a-Si films exhibited lithium alloying and de-alloying reactions, with a large irreversible capacity during the first cycle. The irreversible capacity was derived from the formation of a solid electrolyte interphase (SEI) along with an incompletely de-alloyed Li-Si phase, as confirmed by ex situ TEM and X-ray photoelectron spectroscopy observations. The discharge and charge capacities of the Si films gradually decreased in the subsequent cycles, despite the fact that no further SEI formation or cracking of the Si layer occurred. Scanning electron microscopy observations combined with energy-dispersive X-ray spectroscopy revealed the miniaturization of the a-Si film in the surface region to generate domains measuring less than a few hundred nanometers. These results suggest that delamination and miniaturization of the a-Si nanodomains from the electrode surface are partly responsible for degradation of the a-Si anode. [ABSTRACT FROM AUTHOR]

A vast array of phenomena, ranging from chemical reactions to phase transformations, are analyzed in terms of a free energy surface defined with respect to a single or multiple order parameters. Enhanced sampling methods are typically used, especially in the presence of large free energy barriers, to estimate free energies using biasing protocols and sampling of transition paths. Kinetic reconstructions of free energy barriers of intermediate height have been performed, with respect to a single order parameter, employing the steady state properties of unconstrained simulation trajectories when barrier crossing is achievable with reasonable computational effort. Considering such cases, we describe a method to estimate free energy surfaces with respect to multiple order parameters from a steady state ensemble of trajectories. The approach applies to cases where the transition rates between pairs of order parameter values considered is not affected by the presence of an absorbing boundary, whereas the macroscopic fluxes and sampling probabilities are. We demonstrate the applicability of our prescription on different test cases of random walkers executing Brownian motion in order parameter space with an underlying (free) energy landscape and discuss strategies to improve numerical estimates of the fluxes and sampling. We next use this approach to reconstruct the free energy surface for supercooled liquid silicon with respect to the degree of crystallinity and density, from unconstrained molecular dynamics simulations, and obtain results quantitatively consistent with earlier results from umbrella sampling. [ABSTRACT FROM AUTHOR]

This study investigates the fabrication and characterization of an innovative nanoelectromechanical system force sensor that utilizes suspended submicron silicon nanowires for detecting multi‐axis forces in the micro‐newton range. The sensor combines microscale shuttle platforms with nanowire piezoresistors along with retaining springs. Its fabrication involves a rather involved set of Si deep etching, doping, metallization, release, and encapsulation processes on silicon‐on‐insulator wafers. Electromechanical characterization demonstrates sensor reliability under mechanical strains up to the level of 10% as well as gauge factor measurements. Dynamic response analysis confirms a high resonant frequency of 12.34 MHz with a quality factor of 700 in air, closely matching simulation results. Thermal characterization of the sensor reveals a Temperature Coefficient of Resistance of 6.4 × 10⁻⁴ °C⁻¹. Sensor characterization under jet flow reveals its ability to detect strong flows demonstrating a resistance change of as much as 2.02% under sustained gas flow through a nozzle. Sensor integration into the gas flow measurement setup demonstrates its versatility in detecting small forces, paving the way for further exploration of thermomechanical factors. Combined with its miniature footprint, the sensor's electromechanical performance hints at applications in the analysis of velocity gradients in microscale flows including micro/nano diffusers and nozzles in small satellite propulsion. [ABSTRACT FROM AUTHOR]

Dynamic nuclear polarization (DNP) has revolutionized the field of nuclear magnetic resonance spectroscopy, expanding its reach and capabilities to investigate diverse materials, biomolecules, and complex dynamic processes. Bringing high-efficiency DNP to the nanometer scale would open exciting avenues for studying nanoscale nuclear spin ensembles, such as single biomolecules, virus particles, and condensed matter systems. Combining pulsed DNP with nanoscale force-detected magnetic resonance measurements, we demonstrated a 100-fold enhancement in the Boltzmann polarization of proton spins in nanoscale sugar droplets at 6 kelvin and 0.33 tesla. Crucially, this enhancement corresponds to a factor of 200 reduction in the averaging time compared to measurements that rely on the detection of statistical fluctuations in nanoscale nuclear spin ensembles. These results substantially advance the capabilities of force-detected magnetic resonance detection as a practical tool for nanoscale imaging. [ABSTRACT FROM AUTHOR]