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Light and pressure sensors based on PVDF with sprayed and transparent electrodes for self-powered wireless sensor nodes
摘要： In this work, we report on the fabrication of light and pressure sensors based on the piezo-and pyro material polyvinylidene fluoride (PVDF). In addition to the operation as sensors, the presented devices are characterized as energy harvesters. To form an electrical connection to the 39 μm thick PVDF foil, solution-based and transparent electrode (TE) materials such as silver nanowires (AgNWs) and poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) are utilized and compared with commercial aluminum electrodes on polymer substrate. We show that the performance with regard to sensitivity and generated output power of the TE-PVDF devices outperforms the one for the aluminum foil devices. For the piezo- and pyroelectric effect, a pressure and light sensitivity of 3.6 mV/Pa and 42 V cm2/W, respectively, are measured. The maximum RMS power for the piezo- and pyro effect yield to 1 μW and 0.42 μW, respectively, for an active PVDF area of 8 cm2. At the end of this contribution, we show that this power suffices to drive an energy autarkic wireless sensor node (WSN) that is capable of measuring and transmitting an analog sensor signal using ultra-low power components. This application contributes substantially to the notion of the internet of things (IoT) since paramount aspects such as wireless technology, embedded electronics, and environmental sensor data together with an ultra-low power management are addressed.
关键词： wireless sensor nodes,PEDOT:PSS,WSN,Internet of Things,IoT,spray deposition,energy harvesting,silver nanowires,transparent electrodes
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission from Au nanoparticles decorated ZnO nanowires
摘要： ZnO nanowires with Au nanoparticle decoration were prepared. Photoluminescence results reveal quenching of both the band edge and visible emissions of ZnO nanowires after the Au nanoparticle decoration. The field emission properties fro\ Au nanoparticles decorated ZnO nanowires were measured and increasing turn-on fields were observed. The observed phenomena were attributed to electron transport between ZnO and Au nanoparticle.
关键词： ZnO nanowires,Au nanopartical,field-emisison,electron transport
更新于2025-09-23 15:21:21
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[Nanostructure Science and Technology] Nanowire Electronics || One-Dimensional Nanowire-Based Heterostructures for Gas Sensors
摘要： Gas sensors with the ability to detect gaseous species in a quantitative and qualitative manner play an important role in various aspects in our daily lives. They can function as a feasible means to monitor air quality, environmental pollution, chemical detection, control of chemical processes, food quality, and medical diagnosis and so forth. One-dimensional (1D) nanostructures at least one dimension in the range of 1–100 nm (nanowires, nanorods, nanoribbons or nanobelts, nano?bers) have long been considered as promising building blocks for gas sensors [1–7]. The fascinating features of nanowires for gas sensing include high surface-to-volume ratio, sensitive surface, high crystallinity, high carrier mobility, low power consumption and ease for device integration [2, 6, 8, 9]. In 2001 nanowires were initially employed to fabricate gas sensors as proof-of-concept [2, 3]. Afterwards nanowires are drawing fast growing interest in the ?eld of gas sensing with an outcome of over 1200 publications in past 15 years from the Web of Science using the keywords nanowire and gas sensor (Fig. 7.1). It is important to note that among these publications metal oxide nanowires hold a dominant position, while other nanowires including organic polymers, metals, and other semiconductors only register a small part (12.6%). It is not strange that n-type ZnO and SnO2 nanowires are the most extensively studied materials for gas sensing because the electron mobility in ZnO and SnO2 is very high (160 and 200 cm2 V(cid:1)1 s(cid:1)1, respectively) with respect to that of other metal oxides such as In2O3, WO3 and TiO2 (100, 10 and 0.4 cm2 V(cid:1)1 s(cid:1)1, respectively).
关键词： speed,heterostructures,sensitivity,nanowires,gas sensors,metal oxide,selectivity,stability
更新于2025-09-23 15:21:21
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[Springer Theses] Electrical Properties of Indium Arsenide Nanowires and Their Field-Effect Transistors || Introduction
摘要： As the miniaturization and integration of solid-state electronic devices has continued to increase rapidly with the demands of high speed, low power consumption and high storage density, the conventional Si-based technology has lost their advantages on fabrication process. Therefore the technologies based on new materials gradually attract researchers’ attention. Among them, Indium Arsenide (InAs) nanowires (NWs) with high electron mobility is one of the most promising candidate. In this chapter, we introduce the advantages of InAs nanowire on electronic devices and the development status of InAs nanowire electronic devices. Also, the topic ideas and chapter arrangements of this thesis are presented.
关键词： solid-state,high electron mobility,electronic devices,InAs nanowires,miniaturization
更新于2025-09-23 15:21:21
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Enhanced Photoelectrochemical Performance and Stability of Si Nanowire Photocathode with Deposition of Hematite and Carbon
摘要： Tremendous efforts have been dedicated to the development of transition metal and/or metal oxide surface coating materials to enhance the activity and stability of photoelectrodes. Nanostructured Si photoelectrodes have shown outstanding photoelectrochemical (PEC) performance due to their effective photon absorption and charge generation, separation, and mobility. While the chemical stability and surface reaction efficiency of Si photoelectrodes still need improvement before commercial application. Herein, we report the design and synthesis of a composite Si photoelectrode with a configuration of C/α-Fe2O3/Si nanowires, which presented a stable photoelectrochemical hydrogen production in neutral electrolyte. The p-Si nanowires were prepared by metal-assisted chemical etching for enhanced optical absorption and decorated with a mesoporous α-Fe2O3 thin film (~80 nm) through pyrolysis of ferrocene. A thin carbon passivation layer (~20 nm) was further deposited through ion sputtering further increasing the stability of the composite structure and low bias photocurrent. The role of α-Fe2O3 and carbon layer have been discussed. The composite photoelectrode shows a stable photocurrent of ~ -27 mA/cm2 in 2 h and an anodic onset potential shift of ~0.33 V relative to the bare Si in the neutral solution.
关键词： Si nanowires,photoelectrochemistry,α-Fe2O3,carbon,hydrogen
更新于2025-09-23 15:21:21
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Composition analysis of Ta <sub/>3</sub> N <sub/>5</sub> /W <sub/>18</sub> O <sub/>49</sub> nanocomposite through XPS
摘要： A characterization of a nanocomposite material consisting of Ta3N5 nanoparticles and W18O49 nanowires is presented. The material is of interest for photocatalytic applications, with a focus on pollution reduction through the photodegradation of dye waste; under white light illumination, the combination of Ta3N5 and W18O49 yielded an enhanced rate of dye degradation relative to Ta3N5 particles alone. The facile method of synthesis is thought to be a promising route for both upscale and commercial utilization of the material. X-ray photoelectron spectroscopy revealed a core–shell composite structure with W18O49 present as an overlayer on Ta3N5; the analyzed spectra for the C 1s, O 1s, Ta 4f, N 1s, W 4f, and Na 1s regions are reported. It should be noted that due to differential charging of the underlying Ta3N5 component relative to the W18O49 shell, an additional uncompensated voltage shift may exist in the Ta 4f and N 1s spectra.
关键词： x-ray photoelectron spectroscopy,XPS,dye degradation,W18O49,nanowires,composite,Ta3N5,photocatalysis
更新于2025-09-23 15:21:21
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<i>(Invited)</i> Large-Scale DFT Study of Ge/Si 3D Nanoislands and Core-Shell Nanowires
摘要： Density functional theory (DFT) calculations have been playing important roles to clarify the structures of semiconductor surfaces at atomic scale. However, DFT studies of complex nanostructures are usually impossible because conventional DFT methods cannot treat large systems containing many thousands of atoms. In this paper, we survey our large scale DFT study on (i) the growth of Ge 3D nanostructure on Si(001) substrate and (ii) the atomic and electronic structures of Si/Ge or Ge/Si core-shell nanowires, using our linear-scaling DFT code CONQUEST. The code uses large-scale DFT techniques and has high efficiency on massively parallel computers. We demonstrate that CONQUEST can calculate the atomic positions of the realistic models of nanostructures observed in experiments and can clarify the unique electronic properties of these nano-structured materials.
关键词： nanoislands,CONQUEST,Ge/Si,DFT,core-shell nanowires
更新于2025-09-23 15:21:21
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Optical properties of ZnO deposited by atomic layer deposition (ALD) on Si nanowires
摘要： In this work, we report proof-of-concept results on the synthesis of Si core/ ZnO shell nanowires (SiNWs/ZnO) by combining nanosphere lithography (NSL), metal assisted chemical etching (MACE) and atomic layer deposition (ALD). The structural properties of the SiNWs/ZnO nanostructures prepared were investigated by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopies. The X-ray diffraction analysis revealed that all samples have a hexagonal wurtzite structure. The grain sizes are found to be in the range of 7–14 nm. The optical properties of the samples were investigated using reflectance and photoluminescence spectroscopy. The study of photoluminescence (PL) spectra of SiNWs/ZnO samples showed the domination of defect emission bands, pointing to deviations of the stoichiometry of the prepared 3D ZnO nanostructures. Reduction of the PL intensity of the SiNWs/ZnO with the increase of SiNWs etching time was observed, depicting an advanced light scattering with the increase of the nanowire length. These results open up new prospects for the design of electronic and sensing devices.
关键词： nanosphere lithography (NSL),atomic layer deposition (ALD),Silicon nanowires (SiNWs),metal-assisted chemical etching (MACE),ZnO
更新于2025-09-23 15:21:21
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New Insights Into the Growth Mechanism of Ultrathin Au Nanowires from Combined In-Situ EXAFS and SAXS Studies
摘要： The synthesis at room temperature of Au nanowires (NWs) in hexane solution of HAuCl4.3H2O, oleylamine and triisopropylsilane, was “in-situ” monitored by means of X-ray Absorption Fine Structure Spectroscopies and Small Angle X-Ray Scattering to determine, under identical synthesis conditions, both the changes of the oxidation state of gold atoms and the evolution of the size and shape of the objects involved in the formation of Au NWs. We propose a multi-stage process for the formation of the NWs: first, Au(III) atoms form a planar-square geometry complex that is continuously reduced to give Au(I) disc-like structures with diameters bigger than that of the final NWs. In a second stage, characteristic length/thickness ratio of these disc-like objects increases to form cylinders, presumably by aurophilic interactions between Au(I) centers and stacking of the discs. When most of the Au atoms have been reduced to Au(I), the reduction to Au(0) begins (third stage) and the NWs grow forming an hexagonal arrangement, separated by a bilayer of oleylamine molecules (fourth stage). Finally, a slow reduction leads the reaction to the final product, formed by bundles of long, ultrathin Au NWs.
关键词： triisopropylsilane,in-situ EXAFS,growth mechanism,SAXS,Au nanowires,oleylamine
更新于2025-09-23 15:21:21
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Horizontal GaN nanowires grown on Si (111) substrate: the effect of catalyst migration and coalescence
摘要： Here, we demonstrate the growth of horizontal GaN NWs on silicon (111) by a surface-directed vapour–liquid–solid (SVLS) growth. The influence of the Au/Ni catalysts migration and coalescence on the growth of the NWs has been systematically studied. A 2-D root-like branched NWs were gown spontaneously through catalyst migration. Furthermore, a novel phenomenon that a catalyst particle is embedded in a horizontal NW was observed and attributed the destruction of growth steady state due to the catalysts coalescence. The transmission electron microscopy (TEM) and photoluminescence (PL), cathodoluminescence (CL) measurement demonstrated that the horizontal NWs exhibit single crystalline structures and good optical properties. Our work sheds light on the horizontal NWs growth and should facilitate the development of highly integrated III?V nanodevices on silicon.
关键词： GaN nanowires,silicon substrate,coalescence,catalyst migration,SVLS growth
更新于2025-09-23 15:21:21