Silicon Nanowires Research Articles

RETRACTED: Nanoscale silicon porous materials for efficient hydrogen storage application

The increasing energy demand and the worldwide energy crisis must be met in large part via the sustainable growth of hydrogen energy, since this economy is relied upon to provide clean and carbon-free energy carriers. It is anticipated that the growing demand for light and heavy fuel cell cars would stimulate the development of onboard solid-state hydrogen technology. The research here concentrates on the importance of various permeable substances such as polymers in general, metallic substances, and complex metal hydrides, even if Si nanostructures (SiNSs) have become known as the obvious contender for solid-state hydrogen storage systems. SiNSs have gained prominence as a leading candidate for solid-state hydrogen storage systems. Renowned for their high storage capacity, SiNSs, including silicon nanowires and quantum dots, exhibit promising potential in addressing challenges associated with traditional hydrogen storage methods, positioning them as a key player in advancing clean and efficient energy storage technologies. SiNSs play a crucial role in advancing solid-state hydrogen storage technology. SiNSs, including silicon nanowires and quantum dots, exhibit high storage capacity. Despite challenges like surface oxidation, SiNS holds promise for efficient hydrogen storage, contributing to the development of sustainable energy solutions and mitigating the environmental impact associated with conventional automotive technologies. We focus on the processes that result in permeable silicon, nanowires made of porous silicon, and Si quantum dots. This investigation elucidates the characteristics and patterns of hydrogen's aid, the value of hydrogen power in automobiles for reducing global warming occurrences, and the potential of using SiNSs for hydrogen storage in tandem with other forms of transition and alkali earth materials to meet these difficulties. It demonstrates how catalysts are critical to fixing the current reversibility and desorption problems with hydrogen energy storage. As a result of the analysis, energy suppliers and Si-based fuel cells may be better able to tailor their services to individual customers' needs, which might boost the growth of the hydrogen energy industry.

Lithiated porous silicon nanowires stimulate periodontal regeneration

Periodontal disease is a significant burden for oral health, causing progressive and irreversible damage to the support structure of the tooth. This complex structure, the periodontium, is composed of interconnected soft and mineralised tissues, posing a challenge for regenerative approaches. Materials combining silicon and lithium are widely studied in periodontal regeneration, as they stimulate bone repair via silicic acid release while providing regenerative stimuli through lithium activation of the Wnt/β-catenin pathway. Yet, existing materials for combined lithium and silicon release have limited control over ion release amounts and kinetics. Porous silicon can provide controlled silicic acid release, inducing osteogenesis to support bone regeneration. Prelithiation, a strategy developed for battery technology, can introduce large, controllable amounts of lithium within porous silicon, but yields a highly reactive material, unsuitable for biomedicine. This work debuts a strategy to lithiate porous silicon nanowires (LipSiNs) which generates a biocompatible and bioresorbable material. LipSiNs incorporate lithium to between 1% and 40% of silicon content, releasing lithium and silicic acid in a tailorable fashion from days to weeks. LipSiNs combine osteogenic, cementogenic and Wnt/β-catenin stimuli to regenerate bone, cementum and periodontal ligament fibres in a murine periodontal defect.

Surface roughening and hemi-wicking: Synergistic impact on flow boiling

This study advances thermal management in flow boiling by investigating the synergy between nanoscale surface structures, hemi-wicking, and bubble dynamics during phase changes, with a particular focus on innovative surface morphology. Nanowires, known for enhancing heat transfer through surface roughening and interfacial wicking, play a crucial role. We highlight the importance of morphological roughening and its synergy with hemi-wicking in enhancing critical heat flux (CHF) in flow boiling. We demonstrate that surfaces functionalized with vertical silicon nanowires show a significant increase in CHF compared to smooth surfaces. This enhancement is attributed to improved liquid supply and prevention of bubble pinning, thus maximizing heat dissipation. However, the absence of hemi-wicking on nano-inspired surfaces unexpectedly leads to a substantial CHF reduction compared to smooth counterparts. By visualizing bubble dynamics under forced convection, we reveal the critical role of hemi-wicking in sustaining continuous liquid supply and postponing the onset of film boiling by ensuring an anti-pinning effect of bubbles. These findings offer valuable insights into interface functionalization and surface morphology design for efficient heat dissipation, emphasizing the often-overlooked role of hemi-wicking in preventing bubble pinning. This knowledge is pivotal for developing compact and high-efficiency cooling technologies.

Nanoengineered micro-supercapacitors based on graphene nanowalls for self-powered wireless sensing system

This work presents a comprehensive investigation of micro-supercapacitors (MSCs) based on graphene nanowalls (GNWs), covering core material synthesis, device fabrication, evaluation, and application demonstrations. Three-dimensional hierarchical GNWs structures are grown successfully by a microwave plasma-enhanced chemical vapor deposition (MPECVD), with detailed descriptions of the synthesis process and underlying mechanisms. The structural and morphological properties of the GNWs are thoroughly analyzed. Several types of MSCs are reported, ranging from thin-film to three-dimensional (3D) MSCs, as well as symmetric to asymmetric MSCs. Thin-film MSC is developed by a novel micromachining process for one-step fabricating GNWs-Ni core-shell composite microstructures. A solid-state MSC utilizing 3D hierarchical electrode is created by a fully micro electro mechanical system (MEMS)-compatible process. This involves depositing GNWs-RuOx hybrid nanostructures onto microstructure scaffolds formed using deep reactive ion etching (deep RIE). Additionally, another 3D MSC utilizes GNWs-PANI electrode material deposited on silicon nanowires generated through metal-assisted chemical etching (MACE) method. To enhance MSCs performance, asymmetric MSC is proposed and realized, incorporating GNWs-MnO2 acting as the positive electrode and carbon black serving as the negative electrode. Furthermore, the successfully combination of the fabricated MSCs with an energy harvesting system is demonstrated. The self-powered sensing system driven by solar energy, with the harvested energy stored in MSCs, is effectively showcased, opening up new possibilities for futuristic MSCs to accumulate and store harvested energy as usable electricity. This demonstration has significant potential in fields such as self-powered wireless IoT sensing systems, offering valuable contributions towards sustainable and autonomous energy solutions.

Review of: "Silicon nanowires are one of the best examples of semiconductor nanostructures that can be made in single crystals with a small diameter of 9 to 0 nanometers."

Review of: "Silicon nanowires are one of the best examples of semiconductor nanostructures that can be made in single crystals with a small diameter of 9 to 0 nanometers."

Review of: "Silicon nanowires are one of the best examples of semiconductor nanostructures that can be made as a single crystal with a diameter of 9 to 0 nm"

Review of: "Silicon nanowires are one of the best examples of semiconductor nanostructures that can be made as a single crystal with a diameter of 9 to 0 nm"

Investigating the binding and mechanical properties of carbon nanotube-encapsulated Si nanowires: A perspective from atomic simulations

Atomic simulations using classical mechanics formalism are used to investigate the interfacial binding between CNTs and silicon nanowires as well as mechanical properties of the CNTs encapsulated silicon nanowires systems. The simulations provide the effect of temperature, systems' cross-sectional radius, interfacial distance, applied tension on their binding degree and deformation behaviors. The simulation results reveal that the spacing and interfaces between CNT and nanowire significantly affect thermal stability and the degree of interfacial binding in the systems. The Lode-Nadai values' distributions in the systems provide insight into the loading states on the atoms both in CNTs and silicon nanowires during tension. The atomic hydrostatic pressures can be used to identify stress-transfer paths in the systems during the elasticity, plasticity, and fracture stages.

Experimental demonstration of scalability in a cavity-free planar silicon-integrated thermoelectric device

We demonstrate the scalability of cavity-free planar integrated thermoelectric (TE) devices using silicon nanowires (Si-NWs), where miniaturizing the thermoelement by shortening the Si-NWs improves the areal power density. Shortening the Si-NW length decreases the temperature difference between the Si-NW ends and the open-circuit voltage. Meanwhile, the integrated number density of the thermoelement is increased by shortening the Si-NW length, thereby preserving the total electrical resistance. Bileg devices comprising both n- and p-type Si-NWs exhibited superior performance compared to unileg devices comprising only n-type Si-NWs. In unileg devices, the hot and cold electrodes in the adjacent thermoelements are interconnected through metal wiring, which leaks heat, resulting in a lowering of the temperature difference between the Si-NW ends. This study yields structural design guidelines for planar-integrated TE devices using Si-NWs.

Validation of minority carrier recombination lifetimes in low-dimensional semiconductors found by analytical photoresponses

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.

High-performance radial junction solar cells on ZnO coated stainless steel with excellent flexibility and durability

High flexibility and industrial compatibility are the key factors for developing large-scale lightweight, wearable, and portable thin film flexible solar cells. Here, a rather flexible and mechanically durable three-dimensional (3D) radial junction (RJ) solar cell has been directly constructed over discrete standing Si nanowires (SiNWs), upon flexible ZnO-coated stainless steel (SS) foil substrates. The ZnO layer deposited on the SS surface can optimize the density of SiNWs to improve the optoelectronic performance. A power conversion efficiency of 6.01% has been accomplished, with open-circuit voltage and photo-current density of 0.76 V and 12.87 mA/cm2, respectively. Remarkably, the outstanding mechanical stability of these RJ devices has been recorded, which can sustain > 4000 cycles of large bending to a radius of 2.5 mm, with only a 7% efficiency decrease. Note that the one-pump-down fabrication procedure of this 3D nanostructure RJ cells upon flexible ZnO-coated SS substrates is compatible with the industrial-mainstream Roll-to-Roll technology, holding thus a strong promise to establishing a simple and low-cost strategy for high-performance and durable flexible photovoltaics.

Unlocking the plasma advantage in elevating the performance of silicon nanowires/ poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate) hybrid solar cell

Silicon Nanowires (SiNWs) can be easily synthesized by following the two-step electroless metal-assisted chemical etching method. These SiNWs are well known for their low reflectivity due to their excellent light-harvesting characteristics. In this paper, we demonstrated the effect of plasma treatment time on the performance of SiNWs solar cells. The 1 min plasma-treated SiNWs/Poly 3,4-[ethylene dioxy thiophene:Polystyrene sulfonate] (PEDOT׃PSS) solar cell showed increased power conversion efficiency than the untreated SiNWs/PEDOT׃PSS solar cell. The photo Current density-Voltage (J-V) analysis showed that the open circuit voltage (VOC) of the plasma treated solar cell for 1 min is higher (270 mV) than that of the untreated solar cell (120 mV). The increase in the value of VOC comes from different factors׃ one is due to the formation of a good interface between the SiNWs and PEDOT׃PSS layer; other is the reduction of defect densities in SiNWs/PEDOT׃PSS heterojunction, consequently the reduction in the recombination processes. Hence from this research, we found that by controlling the plasma treatment on SiNWs, it can improve the SiNWs properties which can further improve the efficiency of the solar cell.

Systematic study of the structural, electronic and optical properties of silicon nanowires

In this work we analyzed the structural, electronic, and optical properties of a set of silicon nanowires oriented in different directions, using the density functional theory. Structural optimization was performed in order to relax the atomic coordinates and cell parameters, after which the electronic band structure and density of states were obtained. Simultaneously, we computed the imaginary part of the dielectric function using the elements of the dipolar matrix. Furthermore, we related the transitions between the Van Hove singularities in the density of states with peaks in the absorption spectra, thus identifying relationships among them, which could be used to characterize the density of states by means of the absorption spectrum. The results showed that the electronic and optical properties depend on the diameter and orientation of the nanowires.

Semiconductor Enhanced rGO/Ag0/ZnO Ternary Hybrid Revealing Charge Transfer Enhancement in SERS Detection of Raman Reporter Molecules

AbstractIn this work, we have investigated the role of the chemical enhancement mechanism in SERS detection on a ternary hybrid substrate fabricated by incorporating ZnO nanostructures into an in situ synthesized reduced graphene oxide/silver composite. The sensing performance of the ternary substrate at various ZnO concentrations is investigated using Raman reporter molecules (RRM) such as Rhodamine 6G and 4‐Mercaptobenzoic acid. The SERS signals show enhancement by adding varied amounts of ZnO, revealing a new way of SERS enhancement by incorporating semiconductor nanostructures rather than conventional hotspot engineering. To probe chemical enhancement, we kept the electromagnetic contribution constant by keeping the same concentration of Ag in all the substrates investigated in this study. The obtained enhanced SERS signals of the probe molecules reveal the contribution from the chemical enhancement mechanism with the addition of ZnO. This vital observation reveals a new gateway in the field of SERS detection for developing a semiconductor‐enhanced, economical, and sustainable SERS substrate.

Field-dependent THz transport nonlinearities in semiconductor nano structures.

Charge transport nonlinearities in semiconductor quantum dots and nanorods are studied. Using a density matrix formalism, we retrieve the field-dependent nonlinear mobility and show the possibility of intra-pulse gain. We further demonstrate that the dynamics of master equations can be captured in an analytical formula for the field-dependent charge carrier mobility, e.g. for two-level systems. This equation extends the linear response theory based Kubo-Greenwood result to nonlinear processes at elevated field strength, easily reached in THz transport spectroscopy. With these tools we analyze the field strength, chirp, temperature and dephasing dependence of the charge carrier mobility in the model system of CdSe quantum dots and wires. Stark broadening and Rabi splitting result in strong alterations of the mobility spectra, pronounced at low temperatures. The mobility spectra are strongly temperature and pulse shape dependent in the nonlinear regime. The findings are of immediate interest e.g. for nonlinear THz generation, conversion and amplification in 6G technology and nano electronics. Our results further enable experimentalists to fit and understand measured charge transport nonlinearities with analytical expressions and to design nanosystems with engineered material properties.

TEM-compatible microdevice for the complete thermoelectric characterization of epitaxially integrated Si-based nanowires.

Nanostructured materials present improved thermoelectric properties due to non-trivial effects at the nanoscale. However, the characterization of individual nanostructures, especially from the thermal point of view, is still an unsolved topic. This work presents the complete structural, morphological, and thermoelectrical evaluation of the selfsame individual bottom-up integrated nanowire employing an innovative micro-machined device compatible with transmission electron microscopy whose fabrication is also discussed. Thanks to a design that arranges the nanostructured samples completely suspended, detailed structural analysis using transmission electron microscopy is enabled. In the same device architecture, electrical collectors and isolated heaters are available at both ends of the trenches for thermoelectrical measurements of the nanowire i.e. thermal and electrical properties simultaneously. This allows the direct measurement of the nanowire power factor. Furthermore, micro-Raman thermometry measurements were performed to evaluate the thermal conductivity of the same suspended silicon nanowire. A thermal profile of the self-heating nanowire could be spatially resolved and used to compute the thermal conductivity. In this work, heavily-doped silicon nanowires were grown on this microdevices yielding a thermal conductivity of 30.8 ± 1.7 W Km-1 and a power factor of 2.8 mW mK-2 at an average nanowire temperature of 400 K. Notably, no thermal contact resistance was observed between the nanowire and the bulk, confirming the epitaxial attachment. The device presented here shows remarkable utility in the challenging thermoelectrical characterization of integrated nanostructures and in the development of multiple devices such as thermoelectric generators.

The dopant (n- and p-type)-, band gap-, size- and stress-dependent field electron emission of silicon nanowires.

This study investigates the electron field emission (EFE) of vertical silicon nanowires (Si NWs) fabricated on n-type Si (100) and p-type Si (100) substrates using catalyst-induced etching (CIE). The impact of dopant types (n- and p-types), optical energy gap, crystallite size and stress on EFE parameters has been explored in detail. The surface morphology of grown SiNWs has been characterized by field emission scanning electron microscopy (FESEM), showing vertical, well aligned SiNWs. Optical absorption and Raman spectroscopy confirmed the presence of the quantum confinement (QC) effect. The EFE performance of the grown nanowire arrays has been examined through recorded J-E measurements under the Fowler-Nordheim framework. The Si NWs grown on p-type Si showed a minimum turn-on field and also a higher field enhancement factor. The band-bending diagram also suggests a lower barrier height of p-type Si NWs compared to n-type Si NWs, which plays a key role in enhancing the EFE performance. These investigations suggest that dopant types (n- and p-types), band gap, crystallite size and stress influence the EFE parameters and Si NWs grown on p-type Si (100) substrates are much more favorable for the investigation of EFE properties.

Progress in the application of silicon-based anode nanotechnology in lithium batteries

With the development of technology, graphite materials in traditional lithium batteries can no longer meet people’s needs due to their relatively low specific capacity, limited charging and discharging rates, and poor safety. Silicon has a very high theoretical specific capacity, far exceeding traditional graphite negative electrode materials, making silicon nanoparticles an ideal choice for improving the energy density of lithium-ion batteries. In this paper, we first introduce the silicon nanoparticle anode and its preparation methods: mechanical ball milling, and thermal cracking, and introduce the application of binders in it. Secondly, the silicon nanowire anode and the chemical deposition method for its preparation are introduced, and the high-performance silicon nanowire lithium battery of Amprius is introduced. Thirdly, the preparation of silicon thin film anode and two types of composite film was introduced. Finally, the three types of silicon nano anodes are summarized and prospected. This paper has reference significance for the future research of silicon-based lithium-ion batteries.

Design of "green" plasmonic nanocomposites with multi-band blue emission for ultrafast laser hyperthermia.

Although non-toxic nanoscale materials are widely employed for different healthcare applications, their performance is still considerably limited. In this paper, various approaches using the environmentally friendly ultrafast laser processing were employed to remodel IV group semiconductor nanostructures and synthesize highly-stable (ξ-potential is up to -47 mV) colloidal solutions of plasmonic (525 nm) nanocomposites with a strong size-dependent chemical content. All nanocomposites exhibited a remarkable lamp-excited multi-band blue emission centred at around 420 nm that is considerably (∼10-fold for Au-SiC) stronger than from nanocomposites prepared by the laser co-fragmentation technique. The latter formed a greater quantity of smaller narrowly dispersed (∼4 nm for Au-Si) plasmonic nanostructures compared to the direct laser ablation method. Moreover, it led to a greater number of semiconductor elements (∼1.7-fold for Au-Ge) in the nanocomposites, which was correlated with lower (∼30%) electrical conductivity. Aqueous colloidal solutions revealed a greater degree (∼80%) of the femtosecond laser-induced heating for all nanocomposites formed by direct laser ablation. These findings highlight the peculiarities of the applied laser processing approaches and considerably facilitate the design of specific multi-modal plasmonic-fluorescence (biosensing, bioimaging, hyperthermia) nanocomposites with a required performance that significantly expands the application area of semiconductor nanostructures.

Silicon nanowire-incorporated efficient and flexible PEDOT:PSS/silicon hybrid solar cells

Highly efficient Si nanowire (SiNW)-incorporated thin-flexible hybrid solar cells in a simple device design are developed on low-cost Si wafers, which may lead to the realization of cost-effective flexible Si hybrid solar cell technology.

Detection of SARS-CoV-2 N protein using AgNPs-modified aligned silicon nanowires BioSERS chip.

The SARS-CoV-2 (COVID-19) pandemic had a strong impact on societies and economies worldwide and tests for high-performance detection of SARS-CoV-2 biomarkers are still needed for potential future outbreaks of the disease. In this paper, we present the different steps for the design of an aptamer-based surface-enhanced Raman scattering (BioSERS) sensing chip capable of detecting the coronavirus nucleocapsid protein (N protein) in spiked phosphate-buffered solutions and real samples of human blood serum. Optimization of the preparation steps in terms of the aptamer concentration used for the functionalization of the silver nanoparticles, time for affixing the aptamer, incubation time with target protein, and insulation of the silver active surface with cysteamine, led to a sensitive BioSERS chip, which was able to detect the N protein in the range from 1 to 75 ng mL-1 in spiked phosphate-buffered solutions with a detection limit of 1 ng mL-1 within 30 min. Furthermore, the BioSERS chip was used to detect the target protein in scarcely spiked human serum. This study demonstrates the possibility of a clinical application that can improve the detection limit and accuracy of the currently commercialized SARS-CoV-2 immunodiagnostic kit. Additionally, the system is modular and can be applied to detect other proteins by only changing the aptamer.