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The study describes the creation of high-quality metal oxide nanotubes via a defined heat treatment process of core-shell nanowires. In situ TEM heating experiments and correlative ex situ observations unravel the dynamical processes at small scales.

The combination of conventional physical vapor deposition and a gas aggregation nanoparticle source enabled the study of model systems of unique material combinations and dimensions. Zr50Cu45Ag5 thin film metallic glasses with varying contents of single-crystalline 5 nm tungsten nanoparticles were synthesized using this technique. This approach provides precise control over nanoparticle shape, size, distribution, and concentration. The films were later annealed at 150 °C, 250 °C, 350 °C, and 450 °C. At room temperature inclusion of 0.01 vol% tungsten nanoparticles caused a 15% increase in the nanoindentation hardness of a thin film metallic glass, while having no significant effect on pop-in length or frequency, as seen in the loading curves. Even more remarkably, at 450 °C a control film containing no nanoparticles experienced significant segregation and subsequent crystallization, whereas this effect was repressed in the tungsten nanoparticle composite thin film metallic glass. Unobstructed by nanoparticles, at high temperatures zirconium diffused to the surface of the film, forming a crystalline layer of up to 80 nm. In contrast, this layer is kept to below 30 nm when the nanoparticles are present. The stabilization of the microstructure is also clear from indentation results, while the hardness of the reference sample changes significantly due to the undesired crystallization, the hardness of the composite remains constant., Thin Solid Films, 773, ISSN:0040-6090, ISSN:1879-2731

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is one of very few analytical techniques allowing sample chemical structure to be characterized in three-dimensional (3D) with nanometer resolution. Due to the excellent sensitivity in the order of ppm-ppb and capability of detecting all ionized elements and molecules, TOF-SIMS finds many applications for analyzing nanoparticle-containing systems and thin films used in microdevices for new energy applications, microelectronics, and biomedicine. However, one of the main drawbacks of this technique is potential mass interference between ions having the same or similar masses, which can lead to data misinterpretation. In this work, we present that this problem can be easily solved by delivering fluorine gas to a sample surface during TOF-SIMS analysis and we propose mechanisms driving this phenomenon. Our comprehensive studies, conducted on complex thin films made of highly mass-interfering elements, show that fluorine modifies the ionization process, leading to element-specific changes of ion yields (which can vary by several orders of magnitude), and affects the efficiency of metal hydride and oxide formation. In conjunction, these two effects can efficiently induce separation of mass interference, providing more representative TOF-SIMS data with respect to the sample composition and significant enhancement of chemical image resolution. Consequently, this can improve the chemical characterization of complex multilayers in nanoscale.

Nanoparticle-reinforced thin films synthesis is often limited by precipitation thermodynamics and kinetics to certain material combinations and nanoparticle size distributions. We demonstrate a new method that allows direct co-deposition of mono-sized nanoparticles with various matrix materials, independent particle size and composition control, yielding flexible material selection, and nanoparticle density spatial variations laterally and depth-wise. Tungsten nanoparticles were co-deposited into magnetron-sputtered copper, giving a uniform distribution of nanoparticles in transmission electron microscopy. To demonstrate the application potential, W nanoparticles stabilized nanograined Cu at 500 °C; pure Cu reference showed significant grain growth. This method opens new possibilities in tailored nanocomposite fabrication.

In this work, we present a comprehensive comparison of time-of-flight secondary ion mass spectrometry (TOF-SIMS) and scanning transmission electron microscopy combined with energy-dispersive X-ray spectroscopy (STEM/EDX), which are currently the most powerful elemental characterization techniques in the nano- and microscale. The potential and limitations of these methods are verified using a novel dedicated model sample consisting of Al nanoparticles buried under a 50 nm thick Cu thin film. The sample design based on the low concentration of nanoparticles allowed us to demonstrate the capability of TOF-SIMS to spatially resolve individual tens of nanometer large nanoparticles under ultrahigh vacuum (UHV) as well as high vacuum (HV) conditions. This is a remarkable achievement especially taking into account the very small quantities of the investigated Al content. Moreover, the imposed restriction on the Al nanoparticle location, i.e., only on the sample substrate, enabled us to prove that the measured Al signal represents the real distribution of Al nanoparticles and does not originate from the artifacts induced by the surface topology. The provided comparison of TOF-SIMS and STEM/EDX characteristics delivers guidelines for choosing the most optimal method for efficient characterization of nano-objects.

Structural colours have received a lot of attention regarding the reproduction of the vivid colours found in nature. In this study, metal–anodic aluminium oxide (AAO)–Al nanostructures were deposited using a two-step anodization and sputtering process to produce self-ordered anodic aluminium oxide films and a metal layer (8 nm Cr and 25, 17.5 and 10 nm of Au), respectively. AAO films of different thickness were anodized and the Yxy values (Y is the luminance value, and x and y are the chromaticity values) were obtained via reflectance measurements. An empirical model based on the thickness and porosity of the nanostructures was determined, which describes a gamut of colours. The proposed mathematical model can be applied in different fields, such as wavelength absorbers, RGB (red, green, blue) display devices, as well as chemical or optical sensors.

The matrix effect, i.e. the dependence of element ion yield on the surrounding chemical state, is very often considered as a negative and limiting factor in elemental characterization. In fact, it is the main reason making Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) a non-quantitative technique as element ionization efficiency can span over several orders of magnitude depending on the matrix. Despite that, even small chemical variations of an experimental setup can cause interpretation of TOF-SIMS depth profiles a challenging task. However, the sensitivity of element ionization to the neighboring atoms can also be very beneficial as ion yields can be enhanced in the presence of particular species such as oxygen, cesium, water and fluorine. In this work, we make an attempt to estimate the matrix effect in two-element Zr-containing alloys using TOF-SIMS. The Zr ionization efficiency as well as its response to the surface and interface contaminants was investigated depending on Al, Si and Cu matrices. It was observed that Zr ionization efficiency is over four times higher in the Si matrix than in the Cu matrix and over two times higher when compared to the results obtained in the Al matrix.

Enhancing the spatial resolution of Time-Of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), which provides 3D elemental distribution in combination with high sensitivity and molecular information, is currently one of the hottest topics in the field of chemical analysis at the nanoscale. As the efficiency of the ionization process determines the possibility of imaging a sample's elemental structure in 3D, methods for enhancing secondary ion generation are of particular interest. Recently, a novel approach of combining a high-vacuum compatible compact TOF-SIMS detector with a Gas Injection System (GIS) integrated within a Focused Ion Beam (FIB) instrument has been demonstrated on pure metals. In this work, we present a comprehensive study on water vapor and fluorine gas-assisted TOF-SIMS conducted on dedicated Zr-based model samples (ZrAl, ZrSi and ZrCu) to verify whether the application scope of this method can be expanded to more complex alloys. The main concerns of potential preferential sample sputtering and sample isotope abundance content degradation caused by the introduced gas were excluded. Moreover, fluorine gas improved the accuracy of the measured Zr isotope contents. In most cases, the ion yields were significantly increased. Furthermore, gas co-injection seemed to mitigate variations in element ionization along the thin film, allowing us to obtain more representative TOF-SIMS data regarding sample composition. Compared to the results obtained under standard vacuum conditions, the alloys' sputtering rates decreased by up to 46% when using water vapor and almost doubled in the case of fluorine gas.

The increasing demand for functional materials and an efficient use of sustainable resources makes the search for new material systems an ever growing endeavor. With this respect, architected (meta-)materials attract considerable interest. Their fabrication at the micro- and nanoscale, however, remains a challenge, especially for composites with highly different phases and unmodified reinforcement fillers. This study demonstrates that it is possible to create a non-cytotoxic nanocomposite ink reinforced by a sustainable phase, cellulose nanocrystals (CNCs), to print and tune complex 3D architectures using two-photon polymerization, thus, advancing the state of knowledge toward the microscale. Micro-compression, high-res scanning electron microscopy, (polarised) Raman spectroscopy, and composite modeling are used to study the structure-property relationships. A 100% stiffness increase is observed already at 4.5 wt% CNC while reaching a high photo-polymerization degree of ≈80% for both neat polymers and CNC-composites. Polarized Raman and the Halpin-Tsai composite-model suggest a random CNC orientation within the polymer matrix. The microscale approach can be used to tune arbitrary small scale CNC-reinforced polymer-composites with comparable feature sizes. The new insights pave the way for future applications where the 3D printing of small structures is essential to improve performances of tissue-scaffolds, extend bio-electronics applications or tailor microscale energy-absorption devices.

Nanocrystalline (nc) alloys are stronger than their coarse-grained versions. Here, we report ultrastrong alloys, discovered via high-throughput screening of the nc CoCr33-69 materials library. The nc materials library was fabricated using magnetron co-sputtering. The alloys consist of textured, columnar structures with grain size in the nanometric regime. We found that the texture and phase composition can be tailored by changing the Cr concentration. In the investigated region of the nc CoCr system, a relatively broad spectrum of yield strength, determined via micropillar compression tests, was found ranging from 1.41 GPa up to 3.64 GPa. The remarkable strength increment was caused by a chemically- and thermally-driven phase and microstructure evolution of the system. The strongest alloys were found in the regions containing the δCoCr phase, which was considered previously as metastable. Density functional calculations revealed that the δCoCr phase is more energetically favourable in Cr-rich regions compared to single-phase simple solid solutions (HCP, BCC). Experimental results showed that the range of its occurrence is wider than previously thought, i.e. after annealing the δCoCr phase was found above 44 at. % of Cr. We demonstrate that systematic screening of materials libraries can boost the discovery of new materials with outstanding properties.

Combining a Gas-Injection System (GIS) with the Focused Ion Beam (FIB) has a broad scope of applications in sample preparation such as protective layer deposition, increasing material sputtering rates, and reducing FIB-related artifacts. On the other hand, injecting certain specific gases during a Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) analysis can significantly increase element ionization probability and, therefore, improve the quality of 3D representation of a sample elemental structure. In this work, for the first time, the potential of GIS for enhancing secondary ion signals acquired using a TOF detector incorporated into a commercial Ga

Materials 14(12), 3357 (1-17) (2021). doi:10.3390/ma14123357, A nanocrystalline Co-Cr-Ni-Fe compositional complex alloy (CCA) film with a thickness of about 1 micron was produced by a multiple-beam-sputtering physical vapor deposition (PVD) technique. The main advantage of this novel method is that it does not require alloy targets, but rather uses commercially pure metal sources. Another benefit of the application of this technique is that it produces compositional gradient samples on a disk surface with a wide range of elemental concentrations, enabling combinatorial analysis of CCA films. In this study, the variation of the phase composition, the microstructure (crystallite size and defect density), and the mechanical performance (hardness and elastic modulus) as a function of the chemical composition was studied in a combinatorial Co-Cr-Ni-Fe thin film sample that was produced on a surface of a disk with a diameter of about 10 cm. The spatial variation of the crystallite size and the density of lattice defects (e.g., dislocations and twin faults) were investigated by X-ray diffraction line profile analysis performed on the patterns taken by synchrotron radiation. The hardness and the elastic modulus were measured by the nanoindentation technique. It was found that a single-phase face-centered cubic (fcc) structure was formed for a wide range of chemical compositions. The microstructure was nanocrystalline with a crystallite size of 10–27 nm and contained a high lattice defect density. The hardness and the elastic modulus values measured for very different compositions were in the ranges of 8.4–11.8 and 182–239 GPa, respectively., Published by MDPI, Basel

In this work, we present the potential of high vacuum-compatible time-of-flight secondary ion mass spectrometry (TOF-SIMS) detectors, which can be integrated within focused ion beam (FIB) instruments for precise and fast chemical characterization of thin films buried deep under the sample surface. This is demonstrated on complex multilayer systems composed of alternating ceramic and metallic layers with thicknesses varying from several nanometers to hundreds of nanometers. The typical problems of the TOF-SIMS technique, that is, low secondary ion signals and mass interference between ions having similar masses, were solved using a novel approach of co-injecting fluorine gas during the sample surface sputtering. In the most extreme case of the Al/Al2O3/Al/Al2O3/.../Al sample, a

Structural colours have produced immense attention in reproducing the vivid colours found in nature. In this study, metal-anodic aluminium oxide (AAO)-Al nanostructures were deposited using a two-step anodization and sputtering process to produce self-ordered anodic aluminium oxide films and a metal layer (8 nm Cr and 25,17.5 and 10 nm of Au), respectively. AAO films, of various thicknesses, were anodized and the Yxy values (Y, luminance, and xy, chromaticity) were obtained via reflectance measurements. An empirical model, based on the thickness and porosity of the nanostructures, was determined, which would describe a gamut of colours. The proposed mathematical model can be applied in different fields, such as wavelength absorbers, RGB (red, green, blue) display devices, as well as chemical or optical sensors.

Physical vapor deposition (PVD) is a well-known route for manufacturing hard coatings. In recent years, PVD has also been applied to create high-entropy alloy (HEA) thin films. HEAs are multicomponent alloys with nearly equal atomic fractions. To achieve the desired composition, typically alloy targets are used in the deposition process. The present work demonstrates that HEA thin films can also be processed using a multiple beam sputtering system in PVD, which does not require preliminary manufacturing of HEA targets, but rather uses commercially pure metal targets. The effectivity of this technique was demonstrated on a nanocrystalline CoCrNiFe HEA film with a thickness of about 1 μm. A part of the compositional gradient sample exhibited equal elemental fractions. The microstructure and the hardness of this part of the PVD film were studied in detail, and the results were compared with those obtained on a bulk nanocrystalline sample having the same chemical composition, but was prepared by the high pressure torsion (HPT) technique. The crystallite size and the texture were characterized by X-ray diffraction, while the hardness was measured by nanoindentation. The PVD film exhibited an exceptionally high hardness of 9.8 ± 0.3 GPa, a value that was notably higher than that determined for the HPT sample (7.3 ± 0.3 GPa). This study also demonstrated the capability of this new multiple beam sputtering technique for the production of compositional gradient samples with a wide range of elemental concentrations, enabling combinatorial analysis of multiple elements high-entropy alloy.

An initial study to investigate the effect of controlled deposition of nanoparticles at multilayer interfaces was conducted to explore the mechanical effect of particles on laminate structures. Nanoparticles with diameter of about 4.5 nm were specifically deposited at the interface between Cu and Ni laminates by forced agglomeration of magnetron sputtered ions using a Mantis Ltd. Nanogen50 nanoparticle generator and the hardness of these films were measured using the nanoindentation technique. Cu/Ni laminates without W nanoparticles have an average modulus value of approximately 120 ± 3.7 GPa and hardness value of 2.23 ± 0.07 GPa, while the hardness values of the particle-containing films are greater, regardless of particle density. The areas with the lowest particle density at the interfaces (0.9 at.% W) show the greatest increase in hardness, with an increase of about 1.3 GPa greater than the particle-free sample. However, as the particle density increases, there is a corresponding decrease in hardness. In-situ x-ray diffraction of these films was also conducted to observe the annealing behavior of these films. For all samples, the Cu and Ni layered structure remained intact; however, there is evidence of Ni diffusion along grain boundaries and interaction with the oxygen, likely creating NiO. After annealing, a significant number of the W nanoparticles dissolved into the Ni matrix to create NiW solid-solution. The ability to deposit particles with such precise control has the potential to open up an exciting new field of research. publishedVersion

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) detectors have been intensively developed in recent decades due to their unprecedented capability of representing a sample elemental composition in a three-dimensional space from nano- to submilliscale with high spatial resolution and mass resolution. A compact high-vacuum-compatible version of these detectors can be integrated into a focused ion beam (FIB) system which, assembled with scanning electron microscopy (SEM), is the most popular tool used in nanotechnology and material science. This gives a new opportunity for combining TOF-SIMS analysis with other instruments within the same analytical chamber. In this work we present the results of conducting elemental characterization of a dedicated model multilayer sample composed of 100 nm thick thin films of Cu, Zr, and ZrCuAg alloy in a fluorine gas atmosphere provided by an in situ gas injection system (GIS). In general, the secondary ion signals were significantly enhanced by up to 3 orders of magnitude, leading to much higher spatial resolution. The quality of elemental images and depth profiles was improved during a single measurement (which usually cannot be obtained at standard vacuum conditions) at a high beam energy of 20 keV. Moreover, fluorine assistance has enabled a mass interference between

International audience; Nano crystalline diamond (NCD) films grown at a temperature below 400°C can open new applications on temperature sensitive substrates such as polymers or low-melting point alloys. One requirement for the applicative use of NCD is the ability of depositing on a structured substrate having high aspect ratio. This work presents a study on the three dimensional (3D) conformity of NCD deposition at low temperature (350°C) and low pressure (30 Pa). Silicon wafers have been structured using a mask-less photolithography and (hardmaskless) Deep Reactive Ion Etching (DRIE) process and seeded with nano-diamond particles. The NCD films were grown on these 3D patterned Si substrates with various trench geometries to provide means of determining the limiting geometries of this technique. By measuring the step coverage with changing trench width, a threshold for conformal NCD growth can be determined. The NCD films at the bottom of the 100 μm deep trenches were continuous down to an aspect ratio of 1:7.

Metal-anodic aluminum oxide (AAO)−Al nanostructures have been deposited by using sputtering for the metal layer deposition and a two-step anodization process in different electrolytes to produce self-ordered anodic aluminum oxide films. The effect of the morphological parameters of AAO films (such as thickness, pore diameter, interpore distance, and porosity) on the optical properties was studied. The UV−vis reflectance properties as a function of the thickness for the different electrolytes of metal-AAO−Al films were analyzed in order to obtain the color diagrams and the effective refractive indexes of the films. The effective refractive index was found to depend on the thickness and porosity of AAO films. The change in color observed in metalAAO−Al nanostructures is due to the thickness and porosity of the AAO films. In order to verify the experimental results, UV−vis reflectance spectra of AAO− Al films were simulated using commercially available finite element simulation software, The authors would like to acknowledge financial support from Commission for Technology and Innovation (CTI-16977.2 PFNM-NM) of the Swiss Confederation. C.V.M. would like to acknowledge funding from the Marie Curie Actions cofound program of the EU’s Seventh Research Framework Program (FP7).

A sample geometry is proposed for performing microscale tensile experiments based on a push-pull design. It allows measuring mode 1 fracture toughness under uniform far-field loading. Finite element simulations were performed to determine the geometry factor, which was nearly constant for Young's moduli spanning 2 orders of magnitude. It was further verified that mode 1 stress intensity factor KI is nearly constant over the width of the tension rods and an order of magnitude higher than KII and KIII. Notched samples with different a/w ratios were prepared in (100)-oriented Si by a combination of reactive ion etching and focused ion beam milling. The mode 1 fracture toughness KI,q was constant with a/w and in average 1.02 ± 0.06 MPa√m in good agreement with existing literature. The geometry was characterized and experimentally validated and may be used for fracture toughness measurements of all material classes. It is especially interesting when a uniaxial, homogeneous stress field is desired, if crack tip plasticity is important, or when positioning of the indenter is difficult.

High aspect ratio ZnO nanowires have been uniformly grown into anodic aluminum oxide (AAO) templates by electrodeposition at a constant potential using peroxide solution. The influence of the ZnCl2 to H2O2 concentration ratio, reduction potential and electrodeposition temperature on the diffusion mechanism, filling ratio, morphology and crystallographic orientation of ZnO nanowires is studied. A correlation between the electrodeposition parameters, through the diffusion mechanism, and the morphological and structural properties of the ZnO nanowire arrays is presented. The diffusion coefficient was found to depend on the zinc chloride concentration, reduction potential and electrodeposition temperature for the electrodeposition of ZnO nanowires into AAO templates. The filling ratio was found to be influenced by the reduction potential and electrodeposition temperature. The morphology of ZnO nanowires is affected by the ZnCl2 concentration and reduction potential, but not by the deposition temperature. The crystallographic orientation of the ZnO nanowires depends on the reduction potential. These nanowires exhibit a high aspect ratio and uniform growth up to 50 μm thickness into AAO templates.

Glass has been recently envisioned as a stronger and more robust alternative to silicon in microelectromechanical system applications, including high-frequency resonators and switches. Identifying the dynamic mechanical properties of microscale glass is thus vital for understanding their ability to withstand shocks and vibrations in such demanding applications. However, despite nearly half a century of research, the micromechanical properties of glass and amorphous materials in general are primarily limited to quasi-static strain rates below ∼0.1/s. Here, we report the in situ high-strain-rate experiments of fused silica micropillars inside a scanning electron microscope at strain rates up to 1335/s. A remarkable ductile-brittle-ductile failure mode transition was observed at increasing strain rates from 0.0008 to 1335/s as the deformation flow transitions between homogeneous-serrated-homogeneous regimes. Detailed surface topography investigation of the tested micropillars revealed that at the intermediate strain rate (∼6/s) serrated flow regime, the load drops are caused by the sequential propagation of individual shear bands. Further, analytical calculations and finite element simulations suggest that the atomistic mechanism responsible for the homogeneous stress-strain curves at very high strain rates (∼64/s) can be attributed to the simultaneous nucleation of multiple shear bands along with dissipative deformation heating. This unique rate-dependent deformation behavior of the glass micropillars highlights the importance and need of extending such microscale high-strain-rate studies to other amorphous materials such as metallic glasses and amorphous metals and alloys. Such investigations can provide critical insights about the damage tolerance and crashworthiness of these materials for real-life applications.

A novel microtensile setup was developed to overcome typical issues encountered in small-scale testing, particularly sample fabrication, sample handling, and misalignment. The system features a silicon (Si) gripper, which is able to self-align with the specimen main axis. Finite element simulations were employed to optimize the microtensile specimen geometry and to mechanically characterize the system. Specimens were prepared using focused ion beam milling, while reactive ion etching was employed to produce the grippers. The system was calibrated using single-crystal (100) Si specimens. The strength asymmetry of brittle crystals was investigated on the example of gallium arsenide (GaAs). Microtensile GaAs specimens and square micropillars sharing lowest dimensions of 1.70 ± 0.19 µm were tested along the [001] crystallographic orientation. Micropillars underwent plastic deformation via twinning in {111} planes and exhibited yield stress of 2.60 ± 0.14 GPa. The tensile experiment showed brittle failure at 1.86 ± 0.17 GPa associated with complex fracture surfaces and no measurable dislocation activity.

Nuclear magnetic resonance (NMR) experiments on subnanoliter (sub-nL) volumes are hindered by the limited sensitivity of the detector and the difficulties in positioning and holding such small samples in proximity of the detector. In this work, we report on NMR experiments on liquid and biological entities immersed in liquids having volumes down to 100 pL. These measurements are enabled by the fabrication of high spatial resolution 3D printed microfluidic structures, specifically conceived to guide and confine sub-nL samples in the sub-nL most sensitive volume of a single-chip integrated NMR probe. The microfluidic structures are fabricated using a two-photon polymerization 3D printing technique having a resolution better than 1 μm3. The high spatial resolution 3D printing approach adopted here allows to rapidly fabricate complex microfluidic structures tailored to position, hold, and feed biological samples, with a design that maximizes the NMR signals amplitude and minimizes the static magnetic field inhomogeneities. The layer separating the sample from the microcoil, crucial to exploit the volume of maximum sensitivity of the detector, has a thickness of 10 μm. To demonstrate the potential of this approach, we report NMR experiments on sub-nL intact biological entities in liquid media, specifically ova of the tardigrade Richtersius coronifer and sections of Caenorhabditis elegans nematodes. We show a sensitivity of 2.5x1013 spins/Hz1/2 on 1H nuclei at 7 T, sufficient to detect 6 pmol of 1H nuclei of endogenous compounds in active volumes down to 100 pL and in a measurement time of 3 hours. Spectral resolutions of 0.01 ppm in liquid samples and of 0.1 ppm in the investigated biological entities are also demonstrated. The obtained results may indicate a route for NMR studies at the single unit level of important biological entities having sub-nL volumes, such as living microscopic organisms and eggs of several mammalians, humans included.

Imposing a well defined geometrical shape to an electrode is a suitable way for increasing surface area, as well as optimising the mass transfer phenomenon. By combining electrodeposition with two-photon lithography templates, it is possible to create free-form microscale 3D metal architectures with almost complete freedom. This work features nickel and nickel copper, as the electrodeposition of these materials is well studied and they are frequently used catalysts for oxygen and hydrogen evolution reaction (OER and HER). Control over the electrodeposition of nickel and nickel copper into the complex templates was achieved by creating 3D time-dependent electrodeposition simulations to predict the optimal experimental conditions and deposition parameters. The simulations are based on various electrochemical measurements of the two systems, such as rotating disc electrode measurements, cyclic volatammetry and chrono-potentiometry. An additional benefit of the simulations is that it can be used prior to the experiment to determine the feasibility of a given design to be electrodeposited. We successfully deposited various 3D architectured electrode microstructures made of nickel and nickel copper.

In the last years, wide band gap semiconductors have received great interest due to their wide application range. Specifically, one-dimensional structures of these semiconductors are candidates for many applications. ZnO is an ideal candidate, as it is an n-type semiconductor with a hexagonal structure, a direct wide band gap of 3.36 eV, high electron mobility, and large excitation energy of 60 meV at room temperature. This semiconductor exhibits an efficient emission in the ultraviolet and visible range, so it is also promising for UV detection applications. ZnO one-dimensional structures (nanowires) are a promising candidate for efficient UV detectors if they fulfill three requirements: high aspect ratio (length/pore diameter) to obtain high on/off current ratios in UV detectors, oriented along the c-axis of the hexagonal structure to reach high electrical properties for the photodetector, and ZnO nanowires should be ordered perpendicular to the substrate to provide excellent light trapping and improve absorption. In this study, ZnO nanowires have been grown at constant electrochemical deposition. Electrodeposition of ZnO was performed using a standard three-electrode cell, where the working electrode was home made anodic aluminum oxide (AAO) templates, the counter electrode was a Pt mesh, and the reference electrode was Ag/AgCl. The electrolyte used in the electrodeposition was peroxide solution (0.005 M ZnCl2 + 0.1 M KCl + 0.04 M H2O2). ZnCl2 concentration were changed from 0.001 M to 0.01 M. The electrodeposition temperature was 70, 75, and 80 °C. The morphology, uniform growth, and filling ratio were controlled by the ZnCl2 concentration, applied potential, and electrodeposition temperature. At 70 °C and using 0.005 M ZnCl2 in the electrolyte, high aspect ratio, uniform growth, and filling ratio ZnO nanowires were obtained by Scanning Electron Microscopy. The crystallographic structure of the nanowires was controlled by applied potential around the reduction potential of ZnO. X-Ray Diffraction confirms that the nanowires are pure ZnO. The main advantages of growing ZnO nanowires by electrodeposition into AAO are the order of the nanostructures, and perfect control nanowires geometry. Moreover, the electrical properties can be measured in ZnO nanowires embedded into AAO, after removing AAO, and single nanowires. The effect of the pore diameter and length of ZnO nanowires on IV curves, and photoresponse is a wide field waiting to be explored.