Nanowire Forests Research Articles

Mass growth of metal nanowire forests

Mass growth of metal nanowire forests

High mass loading potassium ion stabilized manganese dioxide nanowire forests for rechargeable Zn batteries

Manganese dioxide (MnO2) represents an ideal cathode material for rechargeable aqueous Zn batteries due to its high theoretical capacity (308 mAh g−1), suitable potential (1.4 V vs. Zn2+/Zn), natural abundance, and negligible toxicity. However, the capacity and rate capability of MnO2 deteriorate significantly in thick electrodes owing to its low electrical and ionic conductivities. Herein, we report the design of high mass loading potassium ion stabilized α-MnO2 (K0.133MnO2) nanowire forests on carbon cloth through a seed-assisted hydrothermal method for Zn batteries. The vertically aligned K0.133MnO2 nanowire forests with uninterrupted charge transport afford a high area capacity of 3.54 mAh cm−2 and a capacity retention of 79.2% over 1000 cycles in aqueous electrolyte. Moreover, the high area capacity and cyclability can be readily transferred to quasi-solid-state devices.

High-Performance, Low-Cost, Additively Manufactured Electrospray Ion Sources for Mass Spectrometry.

We report novel 3D-printed electrospray sources for mass spectrometry (MS) that produce twice the signal strength of their mainstream counterparts. Leveraging 3D printing to fabricate in bulk nano- and microscale-featured electrospray emitters, this work shows a path for scalable integration in clinically relevant diagnostics. This solution improves the device performance by simultaneously tuning the surface hydrophilicity, solvent evaporation, and geometry. The emitters are made of stainless-steel (SS) 316L via binder jetting and coated in a conformal, hydrothermally grown zinc oxide nanowire (ZnONW) forest. The printed emitters are designed as surface mount devices that can be directly soldered to printed circuit boards with built-in digital microfluidics as part of an automated device assembly. The electrospray sources use a novel extractor electrode design that enables operation at ∼24% larger bias voltages compared with conventional MS cylindrical inlets. The 3D-printed electrospray emitters were characterized against their state-of-the-art counterparts (coated blades and paper spray). MS data from the 3D-printed electrospray emitters show detection of therapeutically relevant targets at 1 μg/ml concentrations with a variety of solvents; for nicardipine, such emitters attain 116% higher signal-to-noise ratios and far greater stability than their counterparts.

SERS-active immunoassay kit for SARS-CoV‑2 mediated by the cooperative chemical and electromagnetic effects of MXene modified with gold nanowires

Surface-enhanced Raman scattering (SERS) technique with high sensitivity, reliable specificity, and rapid recognition ability exhibits attractive promise for the effective fast-monitoring of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein, a novel SERS-active immunoassay kit for SARS-CoV-2 nucleocapsid (N) protein was prepared by in-situ growing gold (Au) nanowire forests (NFs) onto Ti3C2Tx, which was then modified onto polymethyl methacrylate (PMMA) matrix and encapsulated into kit. It was noted that the Au nanowires with fibrous structures which vertically anchored on Ti3C2Tx served as perfect channels to promote photo-induced charge transfer. The synergistic action of electromagnetic and chemical effects resulted in an enhancement factor (EF) of 1.27 × 107. Furthermore, the unreliable fluctuation of the enhanced signal was eliminated by using the intrinsic Raman signal of the flexible PMMA platform, achieving an improved correlation coefficient (R2) value from 0.950 to 0.990. Moreover, the as-designed immunoassay kit with both high sensitivity and remedied quantitative ability rendered by the Ti3C2Tx@Au NFs-PMMA composite exhibited a powerful performance in the practical detection of N-protein with concentration low to 5.0 × 10−8 mg/mL.

Behavior of a forest of NiFe nanowires in KOH and NaCl solution for water electrolysis

The present work investigates the behavior of nanostructured electrodes consisting of an array of nanowires of NiFe alloy in KOH + 0.5 M NaCl solution. The aim is to explore the possibility of using these electrodes for hydrogen production by seawater electrolysis. Seawater splitting requires a highly selective electrode on the anode side, where the evolution of molecular chlorine or the formation of other active chlorine compounds can compete with the oxygen evolution reaction. Nanostructured electrodes, obtained by template electrosynthesis, were tested at room temperature in KOH + 0.5 M NaCl solution, and the results were compared with those obtained in pure KOH. The results showed that the presence of NaCl does not affect the electrocatalytic behavior of the nanostructured NiFe alloy. Furthermore, the chemical–physical characterizations carried out after the long-term galvanostatic tests, have shown that the nanostructured electrodes are also stable in terms of morphology and composition. In addition, the solution used to perform the long-term galvanostatic tests was analyzed to investigate the possible formation of chlorine compounds. The absence of these compounds, together with the measured potential value measured for the oxygen evolution reaction, which was always lower than the thermodynamic redox potential for the hypochlorite formation reaction, leads us to conclude that these electrodes are potentially suitable for seawater electrolysis.

Metal seeding growth of three-dimensional perovskite nanowire forests for high-performance stretchable photodetectors

Metal halide perovskites have been ubiquitously utilized in both rigid and flexible optoelectronics with high performance. However, developing perovskites-based stretchable optoelectronics is highly challenging because perovskites are intrinsically not stretchable unlike some organic semiconductors. Here, for the first time, we devised a novel metal seeding growth method to obtain three-dimensional (3D) perovskite nanowire forests (NWFs) with excellent mechanical stretchability, akin to the seeding growth of grass in nature. Benefiting from their intrinsic stretchability, perovskite NWFs-based stretchable photodetectors have been demonstrated with excellent photodetection performance. Under 0% strain, the device dark current is as low as 0.18 nA cm-2 at − 2 V bias, contributing to an ultrahigh light-to-dark current ratio (Ilight/Idark) of 1.1 × 105 under 5.5 mW cm-2 illumination. The device also exhibits a high responsivity of 455.3 mA W-1 and specific detectivity of 8.69 × 1012 Jones. Meanwhile, under 80% strain conditions, the device have shown negligible performance drop, especially in the aspect of Ilight/Idark. Our work reports a novel growth process that leads to intriguing 3D perovskite nanostructures with unique mechanical flexibility and stretchability, in addition to high optoelectronic sensing performance. These appealing properties can find applications in high-performance stretchable and wearable optoelectronics in the future.

In-situ grown CuO x nanowire forest on copper foam: A 3D hierarchical and freestanding electrocatalyst with enhanced carbonaceous product selectivity in CO 2 reduction

Electrocatalytic carbon dioxide (CO₂) reduction is considered as an economical and environmentally friendly approach to neutralizing and recycling greenhouse gas CO₂. However, the design of preeminent and robust electrocatalysts for CO₂ electroreduction is still challenging. Herein, we report the <i>in-situ</i> growth of dense CuO<i>_x</i> nanowire forest on 3D porous Cu foam (CuO<i>_x</i>-NWF@Cu-F), which can be directly applied as a freestanding and binder-free working electrode for highly effective electrocatalytic CO₂ reduction. By adjusting the surface morphology and chemical composition of CuO<i>_x</i> nanowires via surface reconstruction, large electrochemically active surface area and abundant Cu(+1) sites were generated, leading to remarkable activity for CO₂ electroreduction. The as-prepared hierarchical conductive electrode exhibited an enhanced Faradaic efficiency of 15.0% for ethanol formation (FE_C₂_H₅_OH) and a total Faradaic efficiency of 69.4% for all carbonaceous compounds (FE_C-total) at a mild applied potential of –0.45 V vs. RHE in 0.1 M KHCO₃ electrolyte. It achieved a 4-fold increase in FE_C-total than that of Cu nanowire forest supported on 3D porous Cu foam (Cu-NWF@Cu-F) obtained by <i>in-situ</i> reduction of the CuO<i>_x</i>-NWF@Cu-F via annealing at H₂ atmosphere, and thereby effectively suppressed the hydrogen evolution side-reaction.

A Free-Standing Polyaniline/Silicon Nanowire Forest as the Anode for Lithium-ion Batteries.

Despite its high theoretical capacity, silicon anode has limited intrinsic conductivity and experiences significant volume changes during charge-discharge. To overcome these issues, facile metal-assisted chemical etching and in-situ polymerization of aniline are employed to produce a dense 1D polyaniline/silicon nanowire forest without noticeable agglomeration as a free-standing anode for lithium-ion batteries. This hybrid electrode possesses high cycling performance, delivering a stable capacity capped at 2 mAh cm-2 for 346 cycles of charge-discharge. Maximum capacity of 2 mAh cm-2 is also achievable at high-rate cell testing of 2 mA cm-2 , which cannot be obtained by the anode with plain silicon wafer and silicon nanowire only. The introduction of polyaniline on the silicon nanowire is shown to reduce the solid electrolyte interface (SEI) resistance, stabilize the SEI layer, further alleviate the effect of volume changes, and boost the conductivity of the hybrid anode, resulting in the high electrochemical performance of the anode.

Three-Dimensional Monolithically Self-Grown Metal Oxide Highly Dense Nanonetworks as Free-Standing High-Capacity Anodes for Lithium-Ion Batteries.

Transition metal oxides (TMOs) have been widely studied as potential next-generation anode materials, owing to their high theoretical gravimetric capacity. However, to date, these anodes syntheses are plagued with time-consuming preparation processes, two-dimensional electrode fabrication, binder requirements, and short operational cycling lives. Here, we present a scalable single-step reagentless process for the synthesis of highly dense Mn3O4-based nanonetwork anodes based on a simple thermal treatment transformation of low-grade steel substrates. The monolithic solid-state chemical self-transformation of the steel substrate results in a highly dense forest of Mn3O4 nanowires, which transforms the electrochemically inactive steel substrate into an electrochemically highly active anode. The proposed method, beyond greatly improving the current TMO performance, surpasses state-of-the-art commercial silicon anodes in terms of capacity and stability. The three-dimensional self-standing anode exhibits remarkably high capacities (>1500 mA h/g), a stable cycle life (>650 cycles), high Coulombic efficiencies (>99.5%), fast rate performance (>1.5 C), and high areal capacities (>2.5 mA h/cm2). This novel experimental paradigm acts as a milestone for next-generation anode materials in lithium-ion batteries, and pioneers a universal method to transform different kinds of widely available, low-cost, steel substrates into electrochemically active, free-standing anodes and allows for the massive reduction of anode production complexity and costs.

Cooling‐Accelerated Nanowire‐Nitinol Hybrid Muscle for Versatile Prosthetic Hand and Biomimetic Retractable Claw (Adv. Funct. Mater. 18/2022)

Artificial Muscles In article number 2111145, Il-Kwon Oh and co-workers grow a copper nanowire forest directly on the surface of a shape memory alloy coil (SMAc) to provoke thermal dissipation and accelerate its actuation speed. Then, the cooling-accelerated Cu nanowire grown SMAc is applied as artificial muscles for a versatile prosthetic hand capable of making a series of sign languages and playing the grand piano. Moreover, a unique feature of felines, a retractable claw, is realized by using the cooling-accelerated Cu nanowire grown SMAc for successful control of traction force.

Atomic Layer Deposition Reinforcement of Methylcellulose Nanowire Forests

Micro‐ and nanostructured surfaces are widely used as functional surfaces in various fields including the maritime and medical industries. Many micro‐ and nanocoating technologies are delicate processes that have high costs at scale. Herein, an electrospray deposition (ESD) technique is investigated as an affordable method for obtaining micro/nanostructured surfaces. When processed via ESD from water:ethanol blends, methylcellulose (MC), a fibril gel former, can form nanowire coatings. These nanowires are formed via enhanced gelation by shear forces and surface charges that lead to electrospinning on a drop‐by‐drop basis. However, these ESD MC nanostructures can be easily destroyed upon water exposure. In this work, conformal coating of these MC nanostructures with atomic layer deposition (ALD) of Al2O3 is explored to impart further stability. Upon subsequent heating of the ALD‐coated MC nanostructures, superhydrophobicity can be obtained. It is found that the final ALD‐coated structures exhibit a trade‐off between mechanical stability and hydrophobicity depending on MC nanowire size, with smaller wires being more mechanically robust and larger wires being more hydrophobic.

Cooling‐Accelerated Nanowire‐Nitinol Hybrid Muscle for Versatile Prosthetic Hand and Biomimetic Retractable Claw

AbstractAs strong and shape‐conformable as biological muscles, nitinol shape memory alloys (SMAs) artificial muscles have great merit when applied for bio‐inspired robots. However, the low bandwidth and slow actuation speed of SMAs due to their sluggish cooling have long been troublesome, limiting possible applications. Here, to expedite the cooling rate, a Cu nanowire forest is directly grown on the surfaces of 3D shaped SMA coil (SMAc) to increase the surface area by 15 times and boost thermal convection. As a result, the Cu nanowire forest grown SMA coil (CuNF‐SMAc) shows accelerated cooling compared to bare SMAc (B‐SMAc): the actuation speed of CuNF‐SMAc is 100% faster than that of bare SMAc (B‐SMAc) under natural cooling and 170% faster under forced‐air cooling. With this faster actuation, CuNF‐SMAc artificial muscles are employed in a versatile prosthetic hand to bend and flex fingers. The proposed prosthetic hand successfully demonstrates a series of sign language within 4 s for each letter, and rhythmically plays a grand piano. Moreover, unique retractable feline claws are mimicked which demonstrate a fully tunable frictional force just like how cats do it, expanding the potential of a cooling‐accelerated SMAc artificial muscle.

Recyclable 3D SERS devices based on ZnO nanorod-grafted nanowire forests for biochemical sensing

Three-dimensional (3D) surface-enhanced Raman scattering (SERS) devices have been extensively studied owing to their unique structural advantages. In particular, 3D metal/semiconductor heterostructures with synergistic contribution of plasmonic “hot spots” and charge transfer resonance can exhibit a significant SERS effect. In this work, a novel type of setaria-like 3D nanostructure is fabricated for ultrasensitive SERS detection. The structure is composed of nanowire forests (NWFs) grafted with ZnO nanorods (NRs), which are decorated with Au nanoparticles (NPs). In the 3D Au-ZnO@NWF hybrids, abundant 3D SERS “hot spots” are generated by electromagnetic coupling of the Au NPs densely distributed on the ZnO NRs with three types of spatial location. Under the optimized experimental conditions, a marked SERS enhancement factor of 6.4 × 106 is obtained with a limit of detection (LOD) up to 10−10 M for Rhodamine 6G (R6G). In addition, the relative standard deviation is calculated to be less than 10%, demonstrating the device has good spectral reproducibility. Moreover, the SERS device successfully achieves trace detection of biochemical molecules, with LODs for adenine and p-aminothiophenol of 10−7 M and 10−9 M, respectively. Owing to the photocatalytic properties of ZnO, the SERS device can be reused more than fifteen times while maintaining pristine signal intensity. The novel strategy of constructing heterogeneous nanostructures, and the devices based on these nanostructures are expected to have wide applications in biomedical analysis and environmental pollution monitoring.

Reusable OIRD Microarray Chips Based on a Bienzyme-Immobilized Polyaniline Nanowire Forest for Multiplexed Detection of Biological Small Molecules.

Quantitative detection of multiple biological small molecules is critical for health evaluation and disease diagnosis. In this study, a microarray chip featuring a bienzyme-immobilized polyaniline nanowire forest on fluorine-doped tin oxide (bienzyme-PANI/FTO) is developed for this purpose. On such a chip, the target molecules are oxidized under the catalysis of their attached oxidases to produce hydrogen peroxide, which further induces the partial oxidation of local PANI nanowires in the presence of horseradish peroxidase (HRP) enzyme. The redox state change of PANI nanowires is monitored by the oblique incident reflectivity difference (OIRD) technique in a real-time and wireless manner, thus allowing for quantitative analysis of the target molecules. As typical model targets, hydrogen peroxide, glucose, lactic acid, and cholesterol are successfully detected with low detection limits, excellent specificities, and broad detection ranges, all of which fully meet the requirements for clinical analysis of human serum samples. Simultaneous detection of multiple targets on an individual chip is further demonstrated using the OIRD scanning mode. Meanwhile, by simple electrochemical reduction of the PANI nanowires, the chip is reusable for more than eight detection cycles without evident decay in its performance. The detection principle of this chip is also universal to other small molecules, and thus, it shows great promise as a valuable device to analyze biological small molecules.

Optimization of High-Density Fe-Au Nano-Arrays for Surface-Enhanced Raman Spectroscopy of Biological Samples.

The method of realizing nanostructures using porous alumina templates has attracted interest due to the precise geometry and cheap cost of nanofabrication. In this work, nanoporous alumina membranes were utilized to realize a forest of nanowires, providing a bottom-up nanofabrication method suitable for surface-enhanced Raman spectroscopy (SERS). Gold and iron were electroplated through the straight channels of the membrane. The resulting nanowires are, indeed, made of an active element for plasmonic resonance and SERS as the hexagonal distribution of the nanowires and the extreme high density of the nanowires allows to excite the plasmon and detect the Raman signal. The method to reduce the distance between pores and, consequently, the distance of the nanowires after electrodeposition is optimized here. Indeed, it has been predicted that the light intensity enhancement factor is up to 1012 when the gap is small than 10 nm. Measurements of Raman signal of thiol groups drying on the gold nanowires show that the performance of the device is improved. As the thiol group can be linked to proteins, the device has the potential of a biosensor for the detection of a few biomolecules. To assess the performance of the device and demonstrate its ability to analyze biological solutions, we used it as SERS substrates to examine solutions of IgG in low abundance ranges. The results of the test indicate that the sensor can convincingly detect biomolecules in physiologically relevant ranges.

Suspended Heater Embedded Metal Oxide Nanowire Based Gas Sensor Platform

Introduction Over the past few decades, different types of gas sensors have been developed based on different sensing materials and methods. Among them, semiconducting metal oxide nanomaterials are suitable for gas sensing applications due to their high electron mobility, high surface-to-volume ratio, high crystallinity, and long-term stability. Considerable efforts have been made to improve the performance indicators of metal oxide gas sensors such as sensitivity, selectivity, reaction and recovery time [1]. However, in recent years, there has been growing demand for miniaturization, low power consumption, low cost and mass production, which are the characteristics required for continuous and systematically integrated monitoring and management in the sensor market [2]. Besides, widely used materials for metal oxide gas detection are wide-bandgap semiconducting oxides such as zinc oxide, tin oxide, gallium oxide or indium oxides, which are operate at elevated temperatures (250–600°C) since enough thermal energy of surface redox reaction is required to overcome the activation energy barrier and increase the reaction kinetics in order to realize sensing measurement. Therefore, additional heater systems are required to metal oxide gas sensor and it may cause high power consumption, high cost or occupying a lot of space. Hearin, we propose a nano-heater integrated metal oxide gas sensor that capable of sensing with low power consumption and fast response and of being fabricated at a wafer level through C-MEMS which facilitated sub-micrometer-level carbon patterning due to a dramatic volume reduction during the polymer pyrolysis. The temperature of the metal oxide, the sensing material, can be heated immediately to 600°C within a low power of 7mW. In addition, the maximum temperature of the metal oxide can be easily controlled according to the applied voltage. Therefore, only a voltage source is needed to heat the sensing material. Method Our sensor platforms as shown in Figure a, were fabricated in several steps. First, eave structures for the selective metal coating on a suspended carbon nanowire were fabricated by oxide etching and isotropic silicon etching. Then, the suspended carbon nanowire was fabricated through C-MEMS consisting of two successive photolithography and polymer pyrolysis [3]. Then, we deposited gold on a carbon wire using evaporation as a heater line. Owing to the eave structure and anisotropic evaporation, the gold layer could be connected only through the suspended wire as shown in Figure b. The next step was the deposition of HfO2 as an insulation layer by Atomic Layer Deposition. In what follows, the ZnO nanowire forest (Figure c) was integrated selectively on the middle of a suspended wire structure via seed layer patterning and a hydrothermal process in an autoclave [4]. Due to the high aspect ratio of the carbon nanowire, heat is hard to be released to both posts, resulting in a uniform temperature distribution over 80% of the total length of the wire. Therefore, we used ZnO nanowire forest as a sensing site by growing in the center of the carbon nanowire selectively where the temperature is kept uniform and within the range of the sensing target temperature according to the simulation results (Figure d). In the last, to obtain the electrical signal of sensing material, we deposited gold once more using an E-beam evaporator. Results and Conclusions We have identified the possibility of gas sensing with heater integrated metal oxide sensor platform. Observing that the resistance of the metal oxide decreased rapidly when a voltage was applied, we speculated that the temperature of the metal oxide would have risen immediately according to the Joule-heating principle. Furthermore, the resistance of the metal oxide decreased continuously as the applied-voltage gradually increased. When we applied 1.2V to a gold heater, the resistance of the ZnO dropped to about 1/20 of its room temperature resistance (Figure e) similar when it is heated by an external heater to about 250℃, which is occasionally used temperature condition in the MOS type gas sensor. Detailed gas sensing results will be presented at the conference.

High-Resolution Nanopatterning Method of Carbon Nanofibers with Transition Metal Oxides for Electrocatalysis and Gas Sensing Applications Using Joule Heating and Chemical Vapor Deposition

In the past decade, there has been significant research on carbon-transition metal oxides (TMO) hybrid structures and their applications as novel catalysts and sensors[1-3]. Some of these research efforts include i) development of alternatives to platinum-based electrocatalysts to generate hydrogen and ii) design of hybrid nanofiber-based sensors having a high surface to volume ratio. Carbon-TMO-based structures are strong candidates to fulfill these needs owing to their catalytic and sensing performance. However, typical synthesis processes of these structures, such as hydrothermal deposition of TMO on carbon, or combined pyrolysis of carbon and TMO precursors, are challenging to control and reproduce.Addressing this controllability issue, we recently developed a highly reproducible process at the wafer level to synthesize carbon-TMO structures, consisting of a suspended Glassy Carbon Wire (GCW) coated with WO3-x[4-5]. A monolithic carbon structure featuring a suspended GCW of known diameter and length is microfabricated by first laying a SU-8 fiber on top of a photopatterned SU-8 scaffold, using the nearfield-electrospinning technique, followed by pyrolysis. The WO3-x coating is deposited via Localized Chemical Vapor deposition (LCVD), activated by controlling the temperature profile on the suspended GCW through Joule heating. The length and thickness of the coating are adjusted by manipulating the current through the GCW and monitoring its voltage. The featured suspended GCW is ideal for understanding and describing the LCVD process of different TMOs on carbon. However, a single microstructure is not suitable for a large catalysis process. Therefore, to exploit the catalytic capability of the developed material, a multi-wire carbon-TMO is crucial.Here we report the LCVD technique's development to coat carbon nanofibers (CNF) mats with WO3-x for large-scale catalysis. We prepare the CNFs mats using the far-field electrospinning technique of Polyacrylonitrile/Dimethylformamide (PAN/DMF) solution followed by stabilization and carbonization. We have studied in detail the Joule heating of the CNFs mat, and we have developed a model allowing us to predict its temperature at a certain value of power dissipation used for a controlled chemical vapor deposition process. The deposited WO3-x films at the CNF mats are uniform, and the stoichiometry of the coating can be tuned by a post oxidation process or annealing in an inert atmosphere, yielding different catalytic behavior.[1] R. Wu, J. Zhang, Y. Shi, D. Liu, B. Zhang, Metallic WO2-carbon mesoporous nanowires as highly efficient electrocatalysts for hydrogen evolution reaction, J. Am. Chem. Soc. 137 (22) (2015) 6983-6986.[2] J. Chen, D. Yu, W. Liao, M. Zheng, L. Xiao, H. Zhu, M. Zhang, M. Du, J. Yao, WO3-x nanoplates grown on carbon nanofibers for an efficient electrocatalytic hydrogen evolution reaction, ACS Appl. Mater. Interfaces 8 (28) (2016) 18132-18139[3]Y. Lim, S. Kim, Y.M. Kwon, J.M. Baik, H. Shin, A highly sensitive gas-sensing platform based on a metal-oxide nanowire forest grown on a suspended carbon nanowire fabricated at a wafer level, Sens. Actuators B Chem. 260 (2018) 55-62.[4] Cisquella-Serra, A., Gamero-Castaño, M., Ferrer-Argemi, L., Wardini, J. & Madou, M. Controlled joule-heating of suspended glassy carbon wires for localized chemical vapor deposition. Carbon 156, 329–338 (2020)[5] L. Ferrer-Argemi, E.S. Aliabadi, A. Cisquella-Serra, A. Salazar, M. Madou, J. Lee, Size dependent electrical and thermal conductivities of electro-mechanically-spun glassy carbon wires, Carbon 130 (2018) 87-93.

Morphology regulation of nanowire forests for tumour‐cell behaviours

Morphology regulation of nanowire forests for tumour‐cell behaviours

Seebeck coefficient of silicon nanowire forests doped by thermal diffusion.

Thermoelectric generators made by large arrays of nanowires perpendicular to a silicon substrate, that is, so-called silicon nanowire forests are fabricated on large areas by an inexpensive metal-assisted etching technique. After fabrication, a thermal diffusion process is used for doping the nanowire forest with phosphorous. A suitable experimental technique has been developed for the measurement of the Seebeck coefficient under static conditions, and results are reported for different doping parameters. These results are in good agreement with numerical simulations of the doping process applied to silicon nanowires. These devices, based on doped nanowire forests, offer a possible route for the exploitation of the high power factor of silicon, which, combined with the very low thermal conductivity of nanostructures, will yield a high efficiency of the conversion of thermal to electrical energy.

Photon Sieving: Selective and Sensitive Photon Sieve Based on III–V Semiconductor Nanowire Forest Fabricated by Lithography‐Free Process (Advanced Optical Materials 17/2020)

Photon Sieving: Selective and Sensitive Photon Sieve Based on III–V Semiconductor Nanowire Forest Fabricated by Lithography‐Free Process (Advanced Optical Materials 17/2020)