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A low-cost chemical solution deposition technique was employed to prepare YBa2Cu3O7-delta (YBCO) nanocomposite films starting from a colloidal solution containing preformed ZrO2 nanocrystals. As previous publications revealed, an increase in the amount of nanocrystals results in a progressive deterioration of the film properties. The parameters that control this process and their interplay are still unknown in detail. Using definitive screening design (DSD), a design-of-experiments approach, allowed determining which of the multiple growth parameters play a key role for improving the superconducting properties of YBCO nanocomposite films even with a large concentration of nanocrystals. In order to show the potential of DSD, it has been applied for the optimization of two different properties: the critical temperature T-c and the full width at half-maximum of the (005) YBCO reflection. This work shows that DSD is a powerful and efficient method that allows optimizing certain processes with a minimal number of experiments.

Y1- x Gd x Ba2Cu3O7-BaHfO3 (YGBCO-BHO) nanocomposite films containing 12 mol% BHO nanoparticles and different amounts of Gd, x , were grown by Chemical Solution Deposition (CSD) on Ni5W substrates in order to investigate the impact of the rare-earth stoichiometry on the structure and superconducting properties of these films. For Gd contents x > 0.5, epitaxial YGBCO-BHO films with an approximate thickness of 270 nm self-field critical current density J c at 77 K ∼ 1,5 MA/cm² were obtained. The field dependence of the critical current density J c( B ) shows a much larger accommodation field and lower exponents α in J c ∼ B −α values compared to pristine YBCO films. This is both due to the high amount of individual nanoparticles in the matrix as observed in TEM images and the higher critical temperatures T c. The results show that the CSD is a potential candidate for the preparation of RE BCO films in long-length coated conductors.

Among other new device concepts, nickel silicide (NiSix)-based Schottky barrier nanowire transistors are projected to supplement down-scaling of the complementary metal-oxide-semiconductor (CMOS) technology as its physical limits are reached. Control over the NiSix phase and its intrusions into the nanowire are essential for superior performance and down-scaling of these devices. Several works have shown control over the phase, but control over the intrusion lengths has remained a challenge. To overcome this, we report a novel millisecond-range flash-lamp-annealing (FLA)-based silicidation process. Nanowires are fabricated on silicon-on-insulator substrates using a top-down approach. Subsequently, Ni silicidation experiments are carried out using FLA. It is demonstrated that this silicidation process gives unprecedented control over the silicide intrusions. Scanning electron microscopy and high-resolution transmission electron microscopy are performed for structural characterization of the silicide. FLA temperatures are estimated with the help of simulations.

Trions, quasi-particles consisting of two electrons combined with one hole or of two holes with one electron, have recently been observed in transition metal dichalcogenides (TMDCs) and drawn increasing attention due to potential applications of these materials in light-emitting diodes, valleytronic devices as well as for being a testbed for understanding many-body phenomena. Therefore, it is important to enhance the trion emission and its stability. In this study, we construct a MoSe2/FePS3 van der Waals heterostructure (vdWH) with type-I band alignment, which allows for carriers injection from FePS3 to MoSe2. At low temperatures, the neutral exciton (X0) emission in this vdWH is almost completely suppressed. The ITrion/Ix0 intensity ratio increases from 0.44 in a single MoSe2 monolayer to 20 in this heterostructure with the trion charging state changing from negative in the monolayer to positive in the heterostructure. The optical pumping with circularly polarized light shows a 14% polarization for the trion emission in MoSe2/FePS3. Moreover, forming such type-I vdWH also gives rise to a 20-fold enhancement of the room temperature photoluminescence from monolayer MoSe2. Our results demonstrate a novel approach to convert excitons to trions in monolayer 2D TMDCs via interlayer doping effect using type-I band alignment in vdWH., 21 pages, including the suppl. materials, accepted at Adv. Fun. Mater

Gas sensors with high sensitivity are crucial for a large amount of applications. This paper shows a sensor packaging concept for highly sensitive 2D-materials such as black phosphorus (BP) or molybdenum disulfide (MoS 2 ). The material needs on the one hand shielding against gases, which will rapidly degrade the material, such as oxygen; on the other hand, a sufficient contact of the measuring gas to function as sensor. For this purpose, flexible packaging should provide semipermeable membranes on the sensor active area. The development of a gas permeation chamber for permeation tests of polymers and sensor test within a sample gas atmosphere is presented in the paper, together with 2D-material sensor characterization.

Metal–organic frameworks (MOFs) are hybrid materials based on crystalline coordination polymers that consist of metal ions connected by organic ligands. In addition to the traditional applications in gas storage and separation or catalysis, the long-range crystalline order in MOFs, as well as the tunable coupling between the organic and inorganic constituents, has led to the recent development of electrically conductive MOFs as a new generation of electronic materials. However, to date, the nature of charge transport in the MOFs has remained elusive. Here we demonstrate, using high-frequency terahertz photoconductivity and Hall effect measurements, Drude-type band-like transport in a semiconducting, π–d conjugated porous Fe3(THT)2(NH4)3 (THT, 2,3,6,7,10,11-triphenylenehexathiol) two-dimensional MOF, with a room-temperature mobility up to ~ 220 cm2 V–1 s–1. The temperature-dependent conductivity reveals that this mobility represents a lower limit for the material, as mobility is limited by impurity scattering. These results illustrate the potential for high-mobility semiconducting MOFs as active materials in thin-film optoelectronic devices. Semiconducting metal–organic frameworks (MOFs) can be of interest for optoelectronics, but charge transport property is rarely elucidated. Here, a π–d conjugated 2D MOF shows band-like charge transport, with room-temperature mobility of 220 cm2 V–1 s–1.

The cathodic delamination of poly(styrene) [PS] model coatings from oxidecovered zinc has been evaluated by scanning Kelvin probe (SKP). Linear and acrylate cross-linked PS model coatings covalently bound to zinc oxide via Zn─O─Si bonds have been prepared. PS was prepared by thermally initiated free radical polymerization in the presence of vinyltrimethoxy silane modified zinc. Cross-linkers ethylene glycol diacrylate (EDA) and hexanediol diacrylate (HDA) were used in some preparations. Resulting polymers are 8–15 nm thick. PS model coatings show a delamination rate of only ≈20% of that of comparable poly(methyl methacrylate) [PMMA] samples. The slower cathodic delamination of PS is attributed to denser chain packing and higher amounts of hydrophobic moieties, leading to a reduction in penetration of corrosive species. As opposed to the situation in PMMA, the addition of HDA increases the delamination rate, due to its flexible chains and hydrophilic groups. The lowest delamination rate is observed in the presence of 25% EDA. Consequently, ester hydrolysis of acrylates accelerates delamination, it is however not the main factor in cathodic delamination of such thin model system. Postprint: Locked until 10.09.2019 due to copyright restrictions. This is the peer reviewed version of an article, which has been published in final form at 10.1002/maco.201810395. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

The oxygen reduction reaction (ORR) under ultrathin electrolyte layers is a key reaction in many processes, from atmospheric corrosion to energy conversion in fuel cells. However, the ORR current under ultrathin electrolyte layers is difficult to measure using conventional electrochemical methods. Hence, reliable data are scarce for the micrometer range and totally missing for the sub-micrometer range of the electrolyte layer thickness. Here, we report a novel hydrogen-permeation-based approach to measure the ORR current underneath thin and ultrathin electrolyte layers. By using a Kelvin-probe-based measurement of the potential, which results from dynamic equilibrium of oxygen reduction and hydrogen oxidation, and the corresponding hydrogen charging current density, the full currentpotential relationship can be constructed. The results shed a new light on the nature of the limiting current density of ORR underneath ultrathin layers of electrolyte © 2021 The Authors. ChemElectroChem published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Colloidal Janus microparticles can be propelled by controlled chemical reactions on their surfaces. Such microswimmers have been used as model systems for the behavior on the microscale and as carriers for cargo to well-defined positions in hard-to-access areas. Here we demonstrate the propagation motion of clusters of magnetic Janus particles driven by the catalytic decomposition of $$\hbox {H}_2\hbox {O}_2$$ on their metallic caps. The magnetic moments of their caps lead to certain spatial arrangements of Janus particles, which can be influenced by external magnetic fields. We investigate how the arrangement of the particles and caps determines the driven motion of the particle clusters. In addition, we show the influence of confining walls on the cluster motion, which will be encountered in any real-life biological system.

Intrinsically fluorescent carbon dots may form the basis for a safer and more accurate sensor technology for digital counting in bioanalytical assays. This work presents a simple and inexpensive synthesis method for producing fluorescent carbon dots embedded in hollow silica particles. Hydrothermal treatment at low temperature (160 °C) of microporous silica particles in presence of urea and citric acid results in fluorescent, microporous and hollow nanocomposites with a surface area of 12 m2 /g. High absolute zeta potential (-44 mV) at neutral pH demonstrates the high electrosteric stability of the nanocomposites in aqueous solution. Their fluorescence emission at 445 nm is remarkably stable in aqueous dispersion under a wide pH range (3-12) and in the dried state. The biocompatibility of the composite particles is excellent, as the particles were found to show low genotoxicity at exposures up to 10 μg/cm2 .

The electric transport properties of a GdBa2Cu3O 7 − δ thin film containing 12 mol% nano-sized BaHfO3 (BHO) particles grown by chemical solution deposition were investigated in a wide range of temperatures (4.2 ≤T ≤ 77 K) and magnetic fields up to μ 0 H = 19 T. The exponent n of the electric field–current density characteristics ( E ∝ J n ) depends on critical current density J c as (n–1) ∝ J c α (α ∼ 0.45) irrespective of measurement temperature for H ∥ c. On the other hand, this relation does not hold for H ∥ ab. The angular dependence of J c is almost similar to that of n except for the angle close to the ab-plane. A dip of n around this angle regime was observed below 77 K, whereas J c exhibited a maximum. At T ≤ 50 K a tiny peak in the dip was observed that increases with decreasing temperatures. These results suggest that the pinning mechanism changes with temperature for H ∥ ab.

Persistent quantum beats between hot trion states are detected with femtosecond transmission microscopy and manipulated by pump-probe polarizations. Induced absorption into excited biexciton levels reveals transfer of coherence between excited states upon femtosecond hole relaxation.

High purity natural based quartz is used as raw material for production of crucibles for solar-grade silicon production. The crucible properties are strongly related to presence of water and hydroxyl groups in the raw material. In this work, in situ temperature-dependent diffuse reflectance infrared (DRIFT) and Raman spectroscopy in the spectral range of the OH stretching modes, 3000–4000 cm−1, were used to investigate water inclusions and hydroxyl groups at temperatures up to 800 °C. DRIFT shows that a substantial amount of liquid water was removed at 700 °C whereas new silanol groups characterised by stretching modes at about 3650 cm−1 were formed above 200 °C. A surface OH mode was also identified by multivariante curve resolution (MCR) of Raman maps. These surface OH groups were interpreted as the sign of formation of a hydrated layer at the surface of inclusions. It was not possible to detect water signals in other types of structural defect like cracks. Images were acquired in an in situ cell showing different stages of the rupture of an inclusion with a diameter of ≈ 8 μm between 400 and 500 °C. The in situ Raman spectrum of the inclusion water showed the typical liquid water bands at room temperature with a maximum moving to higher wavenumbers with increasing temperature. At 400 °C, the single peak at 3645 cm−1 indicated a situation close to the critical point, triggering rupture. The rupture of such large inclusions was thus identified as the dominating channel for the removal of liquid water inclusions. A small inclusion with a diameter ≈ 4 μm, however, was stable even at 800 °C. These small inclusions contain supercritical water, as evidenced by the sharp Raman peak at 3600 cm−1. Via the peak position, the internal pressure in this stable inclusion was estimated to be 90 MPa. Stability may be facilitated by the formation of a hydrated interfacial layer; the different reactivities of the inclusion fluid at different temperatures leads to different interfacial structures at different temperatures. The presented evidence suggests that inclusions with diameter in the range of few μm are the main source of remaining water and hydroxyl groups in thermally treated high purity quartz sand.

Optical whispering gallery mode microresonators (WGM-µRs) are powerful sensitive components with many analytical applications. Here, spherical WGM-µRs have been synthesised in a single-step microwave (MW)-assisted heterophase polymerisation. The microresonators are based on poly(styrene) beads into which the organic lasing dye nile red was incorporated as gain medium in situ during the polymerisation. The particle diameter and diameter distribution of the synthesised particles were tuned in the range of around 200 nm up to 50 µm by adjusting the concentration between stabiliser poly-(N-vinyl pyrrolidone) (PVP) and monomer styrene, and the solvent composition in the dispersion process. Lower water content enabled the synthesis of spherical particles with large size polydispersity, from which WGM-µRs with a variety of diameters were selected. Microspheres with diameters ${\gtrsim}3.5~\mu$m supported WGMs. The WGMs were excited through free space via the fluorescence of the laser dye. Pumping power levels ${\lt}$1 µW were sufficient to excite WGMs. WGM shifts of beads with diameter between ≈5 and 30 µm measured in air and water show a sensitivity up to 54 nm/RIU for the smallest particles. Dye doped WGM-µR in the low µm size range obtained by the MW-assisted polymerisation process with its versatility, low processing times and high yields opens new horizons for the applications of these systems as sensors.

The field of two‐dimensional (2D) materials has stimulated considerable interest in the scientific community. Owing to quantum confinement in one direction, intriguing properties have been reported in 2D materials that cannot be observed in their bulk form. The advent of semiconducting 2D materials with a broad range of electronic properties has provided fascinating opportunities to design and configure next‐generation electronics. One such emerging class is the family of III‐VI monochalcogenides, the two prominent members of which are indium selenide (InSe) and gallium selenide (GaSe). In contrast to transition metal dichalcogenides, their high intrinsic mobility and the availability of a direct bandgap at small thicknesses have attracted researchers to investigate the underlying physical phenomena as well as their technological applications. However, the sensitivity of InSe and GaSe to environmental influences has limited their exploitation in functional devices. The lack of methods for their scalable synthesis further hinders the realization of their devices. This review article outlines recent advancements in the synthesis and understanding of the charge transport properties of InSe and GaSe for their integration into technological applications. A detailed summary of the improvements in the device structure by optimizing extrinsic factors such as bottom substrates, metal contacts, and device fabrication schemes is provided. Furthermore, various encapsulation techniques that have been proven effective in preventing the degradation of InSe and GaSe layers under ambient conditions are thoroughly discussed. Finally, this article presents an outlook on future research ventures with respect to ongoing developments and practical viability of these materials.

The shape of objects has a strong influence on their dynamics. Here, we present comparative studies of two different motile objects, spherical Ag/AgCl Janus particles and polystyrene Janus nanorods, that move due to an ionic self-diffusiophoretic propulsion mechanism when exposed to blue light. In this paper, we propose a method to fabricate Janus rodlike particles with high aspect ratios and hemispherical tip shapes. The inherent asymmetry due to the ratio between capped and uncapped parts of the particles as well as the shape anistropy of Janus nanorods enables imaging and quantification of rotational dynamics. The dynamics of microswimmers are compared in terms of velocities and diffusion coefficients. We observe that despite a small amount of the Ag/AgCl reagent on the surface of rodlike objects, these new Janus micromotors reveal high motility in pure water. While the velocities of spherical particles reach 4.2 μm/s, the single rodlike swimmers reach 1.1 μm/s, and clusters reach 1.6 μm/s. The effect of suppressed rotational diffusion is discussed as one of the reasons for the increased velocities. These Janus micro- and nanomotors hold the promise for application in light-controlled propulsion transport.

Zinc and its alloys are widely used in the surface protection of metallic structural materials. Thus, zinc is an interesting and relevant candidate material for preparing stimuli-responsive surfaces. In this work, the switching of the optical appearance of zinc between black and white by an applied electrode potential is demonstrated. The zinc surface was covered by gelatin films and subjected to cyclic voltammetry (CV) in a chloride-containing electrolyte which induced pitting corrosion on the zinc surface. Between the different parts of the CV cycles, a reversible change in optical appearance was observed. During the oxidative half-cycles, the surfaces appear white, and during the reductive half-cycles, the surfaces appear brown to black, i.e. dark. Surface characterisation by x-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy shows that the gelatin coating is slightly oxidised during intial stages of the process, but remains intact and present at the surface. Raman spectra prove the presence of ZnO at the interface. Surface analysis shows only minor differences in composition between the black and white surfaces. Based on the available characterisation data, the white appearance associated with anodic currents is attributed to the formation of a non-passivating ZnO. The black appearance associated with cathodic currents is attributed to reduction of surface-confined zinc species, including ZnO and Zn2+. The role of the gelatin is presumably to prevent diffusion of the dissolution products into solution by complex formation and by acting as a diffusion barrier; gelatin will also affect the morphology of the reduction products. A similar switching was observed when gelatin was added to chloride electrolyte; surface analysis showed gelatin adsorption in this case. The black/white switching may, e.g. be useful for surfaces self-indicating corrosion potentials of galvanised steel. Original Content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

With the research on inorganic 2D semiconductors reaching its zenith, the search for new materials beyond these traditional 2D materials is at a rapid pace. In this article, we present an emerging class of 2D semiconductors, so-called metal-organic frameworks, in terms of their synthesis, intrinsic properties, and underlying charge transport mechanisms. Further, we discuss their potential as active elements in optical applications.

When considering the flow of currents through obstacles, one core expectation is that the total resis- tance of sequential single resistors is additive. While this rule is most commonly applied to electronic circuits, it also applies to other transport phenomena such as the flow of colloids or nanoparti- cles through channels containing multiple obstacles, as long as these obstacles are sufficiently far apart. Here we explore the breakdown of this additivity for fluids of repulsive colloids driven over two energetic barriers in a microchannel, using real-space microscopy experiments, particle-resolved simulations, and dynamical density functional theory. If the barrier separation is comparable to the particle correlation length, the resistance is highly non-additive, such that the resistance added by the second barrier can be significantly higher or lower than that of the first. Surprisingly, in some cases the second barrier can even add a negative resistance, such that two identical barriers are easier to cross than a single one. We explain this counterintuitive observation in terms of the structuring of particles trapped between the barriers.

REBa$_{2}$Cu$_{3}$O$_{7}$−x (REBCO, RE = rare earth) compounds with different single RE elements were grown via TFA-MOD (metal-organic deposition of trifluoroacetates) to clarify their T$_{c}$ values when grown by the same preparation method and their processing windows; here: the crystallisation temperatures at a constant process gas composition (pO$_{2}$, pH$_{2}$O). We focussed on the lanthanides (Ln) Nd, Sm, Gd, Dy, Ho, Er and Yb as substituents for Y in the REBCO phase and investigated their growth behaviour in terms of resulting physical (inductive T$_{c}$ and J$_{c}$(77 K)) and structural properties (determined by XRD, SEM, TEM). All phases were grown as pristine films on LaAlO$_{3}$ and SrTiOx$_{3}$ and compared to their respective nanocomposites with 12 mol% BaHfO$_{3}$ for in-field pinning enhancement. With regard to T$_{c}$ and J$_{c}$(77 K), the optima of both values shift towards higher growth temperatures for increasing and decreasing RE ion size with respect to yttrium. Highest T$_{c}$ values achieved so far do not show a trend that can solely be related to the RE ionic size. On the contrary, T$_{c,90}$ values of the LnBCO compounds from Sm to Er range between 94.0 and 95.3 K and are, therefore, significantly larger than the highest values of the average-size non-lanthanide, Y, with T$_{c,90}$ = 91.5 K. J$_{c,sf}$ values at 77 K seem to plateau between 5 and 6 MA cm$^{-2}$ from Sm to Er and are again clearly above the maximum values we ever achieved for Y with 4.2 MA cm$^{-2}$. REBCO phase formations of the very small Yb and large Nd turned out to be more difficult and require further adjustment of growth parameters. All REBCO phases investigated here show distinct dependences of T$_{c}$ on the lattice parameter c.

Introduction: For decades the miniaturization of logic circuitry was a result of down scaling of the field effect transistor (FET). This scaling has reached its end and, therefore, new device materials and concepts have been under research for the last years. One approach is to increase the functionality of an individual device rather than scaling down its size. Such a device concept is the reconfigurable FET (RFET), which can be configured to n- or p-polarity dynamically [1]. RFETs are based on Schottky barrier FETs and feature an intrinsic Si nanowire (NW) channel. The Schottky junctions are formed by placing Nickel (Ni) contacts on both ends of the NW and conductive Ni-silicide segments are formed in the NW by an annealing process. In RFETs, two gates are usually placed on top of these Schottky junctions and by the application of electrostatic potential at the gates unipolar n- or p-transport is tuned in the channel. There are several Ni-silicide phases out of which NiSi2 is preferred as it yields sharp NiSi2-Si junctions. Moreover, its metal work function is near the mid bandgap of Si. This enables tuning the RFET to n- or p-transport by respectively bending the bands when applying electrostatic potential at the gates (Fig. 1). Top-down fabrication of Schottky barrier FETs is a pre-requisite for the large-scale integration of RFETs. The challenges in this fabrication process include proper patterning of NWs, obtaining symmetric p- and n-currents and the scalability of the devices. The first two tasks have been solved as reported in [2]. However, the lack of controllable intrusion of silicide into the NWs remains an obstacle for device scalability [3-5]. Here we report that a silicidation process based on millisecond flash lamp annealing (FLA) significantly improves the uniformity of silicide intrusion at the two ends of the NWs. Such a gain in silicidation control will decisively allow creating RFETs with short channel lengths. Fabrication: The devices are fabricated on silicon-on-insulator (SOI) substrates with 20 nm undoped top Si layer and 102 nm buried oxide. Electron beam lithography (EBL) and dry etching are used to fabricate NWs with 20 nm width as described in [3]. NWs are oxidized with a rapid thermal process and a ~6 nm thick SiO2 shell is formed to passivate NW surface. After wet etching SiO2 from desired areas, Ni contacts are placed in those areas using EBL and Ni evaporation. FLA is used for silicidation of the NWs and the results show equally long silicide intrusions (Fig. 2). Results: The FLA process time is much shorter (0.5-20 ms) compared to conventional rapid thermal annealing (RTA) [6]. FLA based silicidation process is developed which, unlike previously reported RTA based processes, can deliver scalable RFETs. High resolution TEM (HRTEM) shows the formation of the desired NiSi2 phase and atomically abrupt Schottky junctions (Fig. 4). This is also confirmed by element mapping based on energy dispersive X-ray spectroscopy (EDXS) (Fig. 3). The transfer characteristics of the device with back-gate operation show an ambipolar behavior with an ON/OFF ratio of 9 orders of magnitude (Fig. 5). The gate voltage (VBG) was swept from -30 V to 30 V and the drain to source voltage (VD) was varied from 0.25 V to 0.75 V. The unipolar behavior can be tuned by fabricating two or more top gates. This will also reduce the additional hysteresis caused by using the buried oxide as a very thick gate dielectric. Applications: The FLA-based silicidation process enables channel scaling. Devices based on this process show promising results and have potential applications as devices with reduced power consumption and low chip area [7]. These RFETs can also be used for the fabrication of power-efficient multi-independent gate-based logic circuits [8]. Moreover, the number of transistors and the chip area consumption can be reduced with the help of these transistors, preserving at the same time the functionality of the integrated circuits [9]. 1.Heinzig, A. et al., Nano Lett., 2011.12(1):pp.119-124. 2.Simon, M. et al.,IEEE Trans Nanotechnol, 2017.16(5):pp.812-819. 3.Khan, B.M. et al., Appl. Sci. 2019. 9(17),3462. 4.Habicht, S. et al., Nanotechnology, 2010. 21(10): pp.105701. 5.Ogata, K. et al., Nanotechnology,2011.22(36):pp.365305. 6.Rebohle, L. et al., Semicond Sci Technol, 2016. 31(10): pp.103001. 7.Gaillardon, P.E. at al., in LATS, 2016, pp.195-200. 8.Rai, S. et al., IEEE Transactions VLSI, 2019.27(3):pp.560-572. 9.Raitza, M., et al., in DATE.2017,pp.338-343.

Fused silica crucibles are commonly used in the fabrication process of solar grade silicon ingots. These crucibles are manufactured from high purity natural quartz sand and as a consequence, their properties are influenced by the presence of water and hydroxyls in the raw quartz. In this work, diffuse reflectance IR, 1H magic angle spinning NMR, and Raman spectroscopy were used to investigate the influence of thermal treatment on water and hydroxyl groups in high purity natural quartz sand. Most of the water in dry sand is present in the form of closed inclusions within the quartz grains which were detected in Raman imaging studies, even after thermally treating the samples at 600 °C. Only after heating to 900 °C did this water completely vanish, most likely as a result of rupturing of the inclusions. However, newly formed OH groups, identified as isolated and hydrogen bound OH were observed as products of the reaction between water and quartz. Similarly, liquid water was observed in NMR spectra even after treatment at 600 °C while at temperatures >900 °C, only non-interacting silanol groups were present. The comparison of the temperature dependence of the IR and NMR spectra also yields insight into the assignment of the OH stretching mode region of the IR spectrum in this system. The intensity of water related bands decreases while the intensity of OH bands first increases and then decreases with increasing temperature. The band intensity of Al-rich defects as well as the characteristic feature at 3200 cm−1 does not follow the temperature dependence of typical water peaks. It is also shown that leaching the quartz sand in HF solution helps to remove water from inclusions, likely by forming pathways for fluid flow inside the quartz grains. Milling of the samples caused formation of an additional type of hydroxyl group, possibly due to partial amorphisation of the surfaces of the quartz grains surface during the process. The results improve the basis for a knowledge-based processes development for the processing of high purity natural quartz. This article is open access CC-BY.

Indium selenide (InSe) and gallium selenide (GaSe), members of the III–VI chalcogenide family, are emerging two-dimensional (2D) semiconductors with appealing electronic properties. However, their devices are still lagging behind because of their sensitivity to air and device fabrication processes which induce structural damage and hamper their intrinsic properties. Thus, in order to obtain high-performance and stable devices, effective passivation of these air-sensitive materials is strongly required. Here, we demonstrate a hexagonal boron nitride (hBN)-based encapsulation technique, where 2D layers of InSe and GaSe are covered entirely between two layers of hBN. To fabricate devices out of fully encapsulated 2D layers, we employ the lithography-free via-contacting scheme. We find that hBN acts as an excellent encapsulant and a near-ideal substrate for InSe and GaSe by passivating them from the environment and isolating them from the charge disorder at the SiO2 surface. As a result, the encapsulated InSe devices are of high quality and ambient-stable for a long time and show an improved two-terminal mobility of 30–120 cm2 V–1 s–1 as compared to mere ∼1 cm2 V–1 s–1 for unencapsulated devices. On employing this technique to GaSe, we obtain a strong and reproducible photoresponse. In contrast to previous studies, where either good performance or long-term stability was achieved, we demonstrate a combination of both in our devices. This work thus provides a systematic study of fully encapsulated devices based on InSe and GaSe, which has not been reported until now. We believe that this technique can open ways for fundamental studies as well as toward the integration of these materials in technological applications.

Metal-organic frameworks (MOFs) are emerging as an appealing class of highly tailorable electrically conducting materials with potential applications in optoelectronics. Yet, the realization of their proof-of-concept devices remains a daunting challenge, attributed to their poor electrical properties. Following recent work on a semiconducting Fe3 (THT)2 (NH4 )3 (THT: 2,3,6,7,10,11-triphenylenehexathiol) 2D MOF with record-high mobility and band-like charge transport, here, an Fe3 (THT)2 (NH4 )3 MOF-based photodetector operating in photoconductive mode capable of detecting a broad wavelength range from UV to NIR (400-1575 nm) is demonstrated. The narrow IR bandgap of the active layer (≈0.45 eV) constrains the performance of the photodetector at room temperature by band-to-band thermal excitation of charge carriers. At 77 K, the device performance is significantly improved; two orders of magnitude higher voltage responsivity, lower noise equivalent power, and higher specific detectivity of 7 × 108 cm Hz1/2 W-1 are achieved under 785 nm excitation. These figures of merit are retained over the analyzed spectral region (400-1575 nm) and are commensurate to those obtained with the first demonstrations of graphene- and black-phosphorus-based photodetectors. This work demonstrates the feasibility of integrating conjugated MOFs as an active element into broadband photodetectors, thus bridging the gap between materials' synthesis and technological applications.

We introduce a new concept for the solution-based fabrication of conductive gold nanowires using DNA templates. To this end, we employ DNA nanomolds, inside which electroless gold deposition is initiated by site-specific attached seeds. Using programmable interfaces, individual molds self-assemble into micrometer-long mold superstructures. During subsequent internal gold deposition, the mold walls constrain the metal growth, such that highly homogeneous nanowires with 20-30 nm diameters are obtained. Wire contacting using electron-beam lithography and electrical conductance characterization at temperatures between 4.2 K and room temperature demonstrate that metallic conducting wires were produced, although for part of the wires, the conductance is limited by boundaries between gold grains. Using different mold designs, our synthesis scheme will, in the future, allow the fabrication of complex metal structures with programmable shapes.

Reduced tin dioxide/copper phthalocyanine (SnOx/CuPc) heterojunctions recently gained much attention in hybrid electronics due to their defect structure, allowing tuning of the electronic properties at the interface towards particular needs. In this work, we focus on the creation and analysis of the interface between the oxide and organic layer. The inorganic/organic heterojunction was created by depositing CuPc on SnOx layers prepared with the rheotaxial growth and vacuum oxidation (RGVO) method. Exploiting surface sensitive photoelectron spectroscopy techniques, angle dependent X-ray and UV photoelectron spectroscopy (ADXPS and UPS, respectively), supported by semi-empirical simulations, the role of carbon from adventitious organic adsorbates directly at the SnOx/CuPc interface was investigated. The adventitious organic adsorbates were blocking electronic interactions between the environment and surface, hence pinning energy levels. A significant interface dipole of 0.4 eV was detected, compensating for the difference in work functions of the materials in contact, however, without full alignment of the energy levels. From the ADXPS and UPS results, a detailed diagram of the interfacial electronic structure was constructed, giving insight into how to tailor SnOx/CuPc heterojunctions towards specific applications. On the one hand, parasitic surface contamination could be utilized in technology for passivation-like processes. On the other hand, if one needs to keep the oxide's surficial interactions fully accessible, like in the case of stacked electronic systems or gas sensor applications, carbon contamination must be carefully avoided at each processing step.

Living radical polymerization is often considered as an unsuitable method of surface modification for reactive metals such as iron. Necessary noble metal catalyst systems may react with the surface to be modified, causing deactivation of the catalyst. Here, surface-initiated atom transfer radical polymerization (SI-ATRP) using the typical CuI-based catalyst was used to synthesize well-defined poly(methyl methacrylate) thin films grafted on iron. Alkoxy- and chloro-silane initiators were anchored to the metal surface via Si-O-Fe bonds in a metal pretreatment step, yielding a thin cross-linked multilayer sol/gel coating. Except for the precursor’s leaving group, the resulting 10s of nm thick polymer layers were almost identical. Assessment of the delamination kinetics of the model coatings by scanning Kelvin probe (SKP) showed the average delamination to be ≈ 40 % lower in the systems with alkoxy-precursor compared to those with chloro-precursor. In addition, the spread of the measured delamination rates decreased to 1/3 in the alkoxy system, despite identical polymers. The higher delamination rate in the case of chloro-precursors was attributed to residual chloride at the interface. Initiator surface coverage differences may also contribute to stability differences. The ATRP-CuI-catalyst is consequently also suitable for surface modification of non-noble metals after appropriate pretreatment. © The Author(s) 2018. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.

Novel two-layer chromium-based coatings comprised of a first layer containing chromium, oxygen and carbon (Cr-O-C) and an oxygen rich (Cr-O) topcoat were electrodeposited from trivalent chromium electrolyte. The complex structure and composition of the coatings were studied using complementary characterization techniques. The electrodeposited oxide was found to be amorphous and oxygen-deficient. In operando ambient pressure X-ray photoelectron spectroscopy when heating the sample from room temperature to 450 ◦C and Raman spectroscopy after the heating ascertained the metastable nature of the oxide. The cathodic delamination of a weak model polymer on these samples was studied using in situ scanning Kelvin probe. © 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The mechanism behind corrosion rate increase of anodised iron under illumination has been studied by comparing photocurrents with corrosion currents from polarisation curves under controlled convection. Under illumination with photon energies larger than the iron oxide band gap of ~2 eV, corrosion current densities increased by maximum 30%, triggered largely by hole annihilation through cation dissolution. Thermal effects in the oxide also play a role. Photocurrent measurements indicate little upward band bending, with fluctuations, in the n-type oxide at open circuit. The contributions of different mechanisms to the photocorrosion rate have been quantified, relevant for steels and photoelectrochemical water splitting. 0010-938X/© 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The impact was examined of surface ordering of 50 nm-thick copper phthalocyanine (CuPc) layers on the layer's susceptibility to ambience-induced degradation processes. The surface morphology of CuPc layers obtained by physical vapor deposition with different deposition rates, 0.01 nm/s (r1) and 0.02 nm/s (r2), was diagnosed applying atomic force and scanning electron microscopes. The images exhibited compact, ordered surface topography with crystallites of homogeneous geometry for a layer with r1 while randomly distributed bigger crystallites on a rougher and more expanded surface for a layer with r2. X-ray diffraction revealed the α-form of phthalocyanine, mostly with an orientation of the a axis perpendicular to the substrate plane. Mean grain size in bulk was slightly larger for CuPc with r2. Energy dispersive X-ray spectroscopy demonstrated an increase of C/Cu and N/Cu elemental ratios compared to the expected composition for both layers but significantly more pronounced for layer with r2. Morphological features and traces of CuPc-air interaction were mirrored also in the Raman spectra. Samples with r2 exhibited an increased peak width, and their peaks were shifted compared to samples with r1, which was attributed to surface disorder. The Raman spectra exhibited the appearance of additional peaks of oxidation products indicating Csingle bondOsingle bondC, Cdouble bond; length as m-dashO and Nsingle bondO bonds, with intensities coinciding to an increased carbon and nitrogen content. More intensive peaks were recorded for layers obtained with higher deposition rate, proving their stronger susceptibility to environment-induced degradation processes. © 2017 Elsevier Ltd. All rights reserved. This is the authors' accepted and refereed manuscript to the article. Locked until January 31st 2019 due to copyright restrictions

A tin oxide/copper phthalocyanine (CuPc) layer stack was investigated with two complementary photoemission methods. Non-destructive analysis of the electronic properties at the SnOx/CuPc interface was performed applying angle-dependent measurements with X-ray photoelectron spectroscopy (ADXPS) and energy-resolved photoemission yield spectroscopy (PYS). The different components (related to oxide layer and organic overlayer as well as to contamination features) observed in the spectra were assigned to a particular layer by relative depth plot analysis. ADXPS allowed determination of the chemical and electronic structure of the investigated samples. The addition of the organic ultra-thin film to the oxide layer caused a significant increase of the structure's photoemission yield. The combination of ADXPS and PYS allowed determination of the work function of constituent layers, and charge transfer phenomena at the SnOx/CuPc buried interface. An interface dipole of 0.23 eV was detected, assigned to charge transfer across the interface from the oxide layer towards the organic film. The energy level alignment at the SnOx/CuPc interface was determined, and presented in a band-like diagram, together with depth-dependent changes of the core energy levels of the structure's constituents. Finally the role of the oxide's defect-related energy levels in the charge transfer was discussed. The results obtained exhibit significance ranging from investigation, basic understanding and application of such hybrid films. Application of these results in hybrid electronic devices can help understanding and furthering this technology. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.

A sample iron molybdenum alloy with 3.4 wt% (2 at%) molybdenum, and pure iron, are exposed to hydrogen sulfide saturated saline solution for up to 56 days. In addition, their behavior under anodic polarization in the same electrolyte is investigated. The initially fast dissolution of the iron molybdenum alloy slows down significantly over time, while iron corrodes with a constant rate. The observed slow down of the corrosion rate can be described well with an exponential decay of the instantaneous corrosion rate with a time constant of (0.15 ± 0.03)/day, which implies stop in corrosion in practical terms after ≈2 weeks. Relationships are discussed between the instantaneous corrosion rate, and the time-averaged integral corrosion rate. Dissolution under anodic polarization of the iron molybdenum alloy is slower than for pure iron. While at certain times, pyrite, FeS2, is found as corrosion product, the main corrosion product is mackinawite, FeS. The latter likely contains a certain fraction of molybdenum in case of the iron molybdenum alloy. On iron molybdenum, corrosion products forming a sealing layer are observed, which slow down further corrosion. The corrosion products on iron molybdenum show better adhesion to the base material surface.

The natural topographical microchannels in human skin have recently been shown to be capable of guiding propagating cracks. In this article we examine the ability to guide fracture by incorporating similar topographical features into both single, and dual layer elastomer membranes that exhibit uniform thickness. In single layer membranes, crack guidance is achieved by minimizing the nadir thickness of incorporated v-shaped channels, maximizing the release of localized strain energy. In dual layer membranes, crack guidance along embedded channels is achieved via interfacial delamination, which requires less energy to create a new surface than molecular debonding. In both membrane types, guided crack growth is only temporary. However, utilizing multiple embedded channels, non-contiguous crack control can be maintained at angles up to 45° from the mode I fracture condition. The ability to control and deflect fracture holds great potential for improving the robustness and lifespan of flexible electronics and stretchable sensors.

Multiple beam interferometry (MBI) evolved as a powerful tool for the simultaneous evaluation of thin film thicknesses and refractive indices in Surface Forces Apparatus (SFA) measurements. However, analysis has relied on simplifications for providing fast or simplified analysis of recorded interference spectra. Here, we describe the implementation of new optics and a generalized fitting approach to 4 × 4 transfer matrix method simulations for the SFA. Layers are described by dispersive complex refractive indices, thicknesses, and Euler angles that can be fitted, providing modeling for birefringent or colored layers. Normalization of data by incident light intensities is essential for the implementation of a fitting approach. Therefore, a modular optical system is described that can be retrofit to any existing SFA setup. Real-time normalization of spectra by white light is realized, alignment procedures are considerably simplified, and direct switching between transmission and reflection modes is possible. A numerical approach is introduced for constructing transfer matrices for birefringent materials. Full fitting of data to the simulation is implemented for arbitrary multilayered stacks used in SFA. This enables self-consistent fitting of mirror thicknesses, birefringence, and relative rotation of anisotropic layers (e.g., mica), evaluation of reflection and transmission mode spectra, and simultaneous fitting of thicknesses and refractive indices of media confined between two surfaces. In addition, a fast full spectral fitting method is implemented for providing a possible real-time analysis with up to 30 fps. We measure and analyze refractive indices of confined cyclohexane, the thickness of lipid bilayers, the thickness of metal layers, the relative rotation of birefringent materials, contact widths, as well as simultaneous fitting of both reflection and transmission mode spectra of typical interferometers. Our analyses suggest a number of best practices for conducting SFA and open MBI in an SFA for increasingly complex systems, including metamaterials, multilayered anisotropic layers, and chiral layers. © 2019 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)

Superconducting GdBa2Cu3O7 films with 2.5 wt% of BaHfO3 were deposited by pulsed laser deposition using an Nd:YAG laser ( λ = 355 nm), and their structural and electrical properties were investigated in dependence of substrate temperature T sub and deposition rate (i.e., laser repetition rate v dep). The irreversibility lines show the strongest shift toward higher magnetic fields at intermediate T sub and lower v dep. The self-field J c decreases by a factor of 2 compared with the pristine sample, but the situation improves in the high field region. The angular dependence of J c at 1, 5, and 9 T shows a large c -axis peak at 180o, which indicates strongly correlated pinning at BHO nanocolumns.

Manganese-based systems are considered as candidate electrocatalysts for the electrochemical oxygen evolution reaction (OER), because of their abundance in biochemical oxygen producing catalyst systems. In this work, the surface of metallic manganese was investigated in situ and operando in potentiodynamic cyclic voltammetry (CV) experiments and potentiostatic chronoamperometry (CA) experiments in NaOH. In both cases, the surfaces were initially reduced. At corresponding potentials, no oxide species can be detected by Raman spectroscopy, though electrochemical data and the absence of dissolution above the reversible potential for reactions of type Mn → MnII indicate that the material is passive. The CV shows anodic peaks at potentials in line with expectations on the basis of thermodynamic data for the oxidation to Mn3O4 and Mn2O3; the thickness of the surface layer increases by a few nm during these peaks, as evidenced by spectroscopic ellipsometry. Dissolution of Mn as evidenced by downstream electrolyte analysis by inductively coupled plasma mass spectrometry in a scanning flow cell (SFC-ICP-MS) of the electrolyte is negligible in the range of electrode potential vs. Ag|AgCl|3 M KCl, EAg|AgCl, up to 0.3 V. Remarkably, Raman spectra already show the occurrence of α-MnO2 at EAg|AgCl > −0.25 V, which is ca. 0.5 V below the potential at which oxidation to MnO2 is expected. This observation is attributed to disproportionation above a certain level of MnIII. For EAg|AgCl > 0.4 V, dissolution sets in, at a constant layer thickness. Above the onset potential of the OER, at EAg|AgCl ≈ 0.6 V, SFC-ICP-MS analysis shows fast dissolution, and the oxide layer thickness is constant or increases. CA experiments during the OER show strong dissolution, and the re-formation of a strongly disordered, β-MnO2-like oxide, which exists in a quasi-stationary state at the interface. Several CV cycles increase the dissolution per cycle and the fraction of α-MnO2 on the surface which cannot be reduced. The high dissolution currents show that metallic Mn is hardly suitable as an OER catalyst, however, at least the MnIV oxides remain stationarily present in the system. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.

Illumination may increase corrosion rates of important engineering metals. In addition to the well-known photoelectrochemical mechanism which increases dissolution via generation of electron-hole pairs, induced convection via local heating can contribute to increased dissolution. Here, corrosion potential shifts of iron in HCl, aqueous NaCl and NaOH upon illumination with O(102 W cm−2) white light have been found to be O (10 mV), accompanied by increased corrosion rates. The increase in corrosion potential can be suppressed by stirring. These results are interpreted in the framework of the mixed potential theory. An increase in the diffusion limited current of the O2 reduction by increased O2 transport to the surface via induced convection leads to increased corrosion potentials, and thus increased corrosion rates. The induced convection mechanism of increased photocorrosion can be recognised by a delayed onset of corrosion potential shifts. In practice, this mechanism is anticipated to be important mainly in thin film electrolytes under strong illumination. © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).

Particle dispersions provide a promising tool for the engineering of functional materials that exploit self-assembly of complex structures. Dispersion made from magnetic colloidal particles is a great choice; they are biocompatible and remotely controllable among many other advantages. However, their dominating dipolar interaction typically limits structural complexity to linear arrangements. This paper shows how a magnetostatic equilibrium state with noncollinear arrangement of the magnetic moments, as reported for ferromagnetic Janus particles, enables the controlled self-organization of diverse structures in two dimensions via constant and low-frequency external magnetic fields. Branched clusters of staggered chains, compact clusters, linear chains, and dispersed single particles can be formed and interconverted reversibly in a controlled way. The structural diversity is a consequence of both the inhomogeneity and the spatial extension of the magnetization distribution inside the particles. We draw this conclusion from calculations based on a model of spheres with multiple shifted dipoles. The results demonstrate that fundamentally new possibilities for responsive magnetic materials can arise from interactions between particles with a spatially extended, anisotropic magnetization distribution. © 2019 American Physical Society.

Metal pretreatment is typically the first step in a reliable corrosion protection system. This work explores the incorporation of complexes between the cyclic oligosaccharide β-cyclodextrin (β-CD) and the molecular organic corrosion inhibitor 2-mercaptobenzothiazole (MBT) into an oxide-based pretreatment layer on metallic zinc. The layers were produced by a precorrosion step in the presence of β-CD. The resulting films have a morphology dominated by spherical particles. X-ray photoelectron spectroscopy investigations of the surfaces show the sulfur atoms of MBT to be partially oxidized but mostly intact. Samples pretreated with such a layer were subsequently coated with a model polymer coating, and the delamination of this model coating from an artificial defect was monitored by a scanning Kelvin probe (SKP). The SKP results show a slow down of delamination after several hours of the ongoing corrosion process for surfaces pretreated with the complexes. Finally, an increase in the electrode potential in the defect was observed, with a subsequent complete stop in delamination and repassivation of the defect after ≈10 h. This repassivation is attributed to the release of MBT after the initiation of the corrosion process. Most likely, the increase of pH, combined with the availability of aqueous solution, facilitates the MBT release after the initiation of a corrosion process. Consequently, complexes formed from β-CD and corrosion inhibitors can be effectively incorporated into inorganic pretreatments, and the inhibitor component can be released upon start of the corrosion process.

We have studied thermally driven magnon spin transport (spin Seebeck effect, SSE) in heterostructures of antiferromagnetic $\alpha$-$\mathrm{Cr_2O_3}$ and Pt at low temperatures. Monitoring the amplitude of the local and nonlocal SSE signals as a function of temperature, we found that both decrease with increasing temperature and disappear above 100 K and 20 K, respectively. Additionally, both SSE signals show a tendency to saturate at low temperatures. The nonlocal SSE signal decays exponentially for intermediate injector-detector separation, consistent with magnon spin current transport in the relaxation regime. We estimate the magnon relaxation length of our $\alpha$-$\mathrm{Cr_2O_3}$ films to be around 500 nm at 3 K. This short magnon relaxation length along with the strong temperature dependence of the SSE signal indicates that temperature-dependent inelastic magnon scattering processes play an important role in the intermediate range magnon transport. Our observation is relevant to low-dissipation antiferromagnetic magnon memory and logic devices involving thermal magnon generation and transport., Comment: Accepted in APL Materials, For Supplementary Material see published version

Polymer brush patterns were prepared by a combination of electron beam induced damage in self-assembled monolayers (SAMs), creating a stable carbonaceous deposit, and consecutive self-initiated photografting and photopolymerization (SIPGP). This newly applied technique, reactive writing (RW), is investigated with 1H,1H,2H,2H-perfluorooctyltriethoxysilane SAM (PF-SAM) on silicon oxide, which, when modified by RW, can be selectively functionalized by SIPGP. With the monomer N,N-dimethylaminoethyl methacrylate (DMAEMA), we demonstrate the straightforward formation of polymer brush gradients and single polymer lines of sub-100 nm lateral dimensions, with high contrast to the PF-SAM background. The lithography parameters acceleration voltage, irradiation dose, beam current and dwell time were systematically varied to identify the optimal conditions for the maximum conversion of the SAM into a carbonaceous deposit. The results of this approach were compared to patterns prepared by carbon templating (CT) under analogous conditions, revealing a dwell time dependency, which differs from earlier reports. This new technique expands the range of CT by giving the opportunity to not only vary the chemistry of the created polymer patterns with monomer choice but also vary the chemistry of the surrounding substrate.

Steels with an aluminium silicon (AS) metallic coating behave passive in standard phosphating solutions. An electrochemical process was used to increase pH near the surface by polarising to potentials in which hydrogen is evolved, subsequently triggering the formation of phosphate coatings. These conversion coatings have similar morphology and composition than those produced on reactive metal surfaces. Size histograms after different active phosphating times obtained from image analysis show instantaneous nucleation of phosphate crystals with subsequent growth. The use of a commercial titanium phosphate based activation bath leads to homogeneous crystal growth, but appears not to affect significantly the crystals observed shortly after nucleation. Phosphating with a sequence of short potential pulses leads to nucleation of new crystals near the interface of previously nucleated crystals and is hence not an alternative to obtain morphologies with small crystals. Comparing layers prepared here with layers on the same AS coating prepared under open circuit conditions using fluoride additives shows that electrochemically grown layers are more homogeneous.

The transport properties of novel device architectures depend strongly on the morphology and the quality of the interface between contact and channel materials. In silicon nanowires with nickel silicide contacts, NiSi 2–Si interfaces are particularly important as NiSi 2 is often found as the phase adjacent to the silicide–silicon interface during and after the silicidation. The interface orientation of these NiSi 2–Si interfaces as well as the ability to create abrupt and flat interfaces, ultimately with atomic sharpness, is essential for the properties of diverse emerging device concepts. We present a combined experimental and theoretical study on NiSi 2–Si interfaces. Interfaces in silicon nanowires were fabricated using silicidation and characterized by high-resolution (scanning) transmission electron microscopy. It is found that {111} interfaces occur in ⟨110⟩ nanowires. A tilted interface and an arrow-shaped interface are observed, which depends on the nanowire diameter. We have further modeled NiSi 2–Si interfaces by density functional theory. Different crystallographic orientations and interface variations, e.g., due to interface reconstruction, are compared with respect to interface energy densities. The {111} interface is energetically most favorable, which explains the experimental observations. Possible ways to control the interface type are discussed.

Journal of the Electrochemical Society 167(2), 021501 (2020). doi:10.1149/1945-7111/ab632c, Published by IOP Publishing, Bristol

The use of self-assembly techniques may open new possibilities in scaling down electronic circuits to their ultimate limits. Deoxyribonucleic acid (DNA) nanotechnology has already demonstrated that it can provide valuable tools for the creation of nanostructures of arbitrary shape, therefore presenting an ideal platform for the development of nanoelectronic circuits. So far, however, the electronic properties of DNA nanostructures are mostly insulating, thus limiting the use of the nanostructures in electronic circuits. Therefore, methods have been investigated that use the DNA nanostructures as templates for the deposition of electrically conducting materials along the DNA strands. The most simple such structure is given by metallic nanowires formed by deposition of metals along the DNA nanostructures. Here, we review the fabrication and the characterization of the electronic properties of nanowires, which were created using these methods.