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This chapter gives a complete but concise introduction to electron cryomicroscopy. The theoretical and practical background is discussed together with a review of applications to the three-dimensional structural analysis of biological macromolecules or macromolecular assemblies. It includes basic descriptions of how to analyse the structures of molecules arranged in the form of two-dimensional crystals, helical arrays or as single particles with or without symmetry. The chapter concludes by anticipating trends towards increased automation, development of better electronic cameras and increasing use of electron tomography for analysis of cell structure. Keywords: cryoTEM; electron cryomicroscopy; electron microscopy; electron scattering; helical particles; icosahedral particles; image processing in cryoTEM; phasing; radiation damage; three-dimensional image reconstruction; two-dimensional crystals

Focused electron beam induced deposition (FEBID) is a direct write technique for depositing materials on a support substrate akin to 3D printing with an electron beam (e-beam). Opportunities exist for merging this existing technique with aberration-corrected scanning transmission electron microscopy to achieve molecular- or atomic-level spatial precision. Several demonstrations have been performed using graphene as the support substrate. A common challenge that arises during this process is e-beam-induced hydrocarbon deposition, suggesting greater control over the sample environment is needed. Various strategies exist for cleaning graphene in situ. One of the most effective methods is to rapidly heat to high temperatures, e.g., 600 C or higher. While this can produce large areas of what appears to be atomically clean graphene, mobile hydrocarbons can still be present on the surfaces. Here, we show that these hydrocarbons are primarily limited to surface migration and demonstrate an effective method for interrupting the flow using e-beam deposition to form corralled hydrocarbon regions. This strategy is effective for maintaining atomically clean graphene at high temperatures where hydrocarbon mobility can lead to substantial accumulation of unwanted e-beam deposition.

Funding: This research was supported by Science Foundation Ireland under Grant Nos. 15/IA/2864, and 12/RC/2276_P2. ADF acknowledges support from EPSRC (EP/L017008/1) and ERC (Grant No. 819346). The engineering of the surrounding photonic environment is one of the most successful approaches routinely used to increase light extraction efficiency and tune the properties of solid state sources of quantum light. However, results achieved so far have been hampered by the lack of a technology that allows for the straightforward fabrication of large scale 3D nano- and microfeatures, with very high resolution and sufficient flexibility in terms of available materials. In this paper we show that Electron Beam Induced Deposition can be a very promising approach to solve this issue, asexemplified by the fabrication of Pt and SiO2 nanofeatures on a membrane containing ordered arrays of site-controlled pyramidal quantum dots. Micro-photoluminescence has been used to compare the emission of the dots before and after the deposition of the structures, remarkably showing both a significant increase in the light extraction efficiency and no degradation of the spectral quality, implying that negligible damage has been caused to the emitter due to the deposition process. This paves the way for novel post-growth processing strategies for epitaxial quantum dots used in both quantum information technologies and lighting applications. Postprint Postprint

Iron pentacarbonyl (Fe(CO)5) is a versatile material that is utilized as an inhibitor of flame, shows soot suppressibility, and is used as a precursor for focused electron-beam-induced deposition (FEBID). X-ray absorption near-edge structure (XANES) of the K edge, which is a powerful technique for monitoring the oxidation states and coordination environment of metal sites, can be used to gain insight into Fe(CO)5-related reaction mechanisms in in situ experiments. We use a finite difference method (FDM) and molecular-orbital-based time-dependent density functional theory (TDDFT) calculations to clarify the Fe K-edge XANES features of Fe(CO)5. The two pre-edge peaks P1 and P2 are mainly the Fe(1s) → Fe–C(σ*) and Fe(1s) → Fe–C(π*) transitions, respectively. When the geometry transformed from D3h to C4v symmetry, a ∼30% decrease of the pre-edge P2 intensity was observed in the simulated spectra. This implies that the π bonding of Fe and CO is sensitive to changes in geometry. The following rising edge and white line regions are assigned to the Fe(1s) → Fe(4p)(mixing C(2p)) transitions. Our results may provide useful information to interpret XANES spectra variations of in situ reactions of metal–CO or similar compounds with π acceptor ligandlike metal–CN complexes.

In this study, the method of direct modification of conductive atomic force microscopy (CAFM) probes using focused electron beam induced deposition (FEBID) of platinum (Pt) nanowire is presented. This method allows the restoration of broken tips, as well as regenerates the conduction. The length and diameter of the modified tips were optimized by changing the duration time and electron beam current. The tip diameter before modification was measured to be approximately ∼50 nm, and that after modification was measured to be approximately ∼15 nm, which was significantly decreased. The AFM images of topography and current were collected from the fabricated samples with circular array structures using both commercial and Pt nanowire modified CAFM probes. The resistance of FEBID modified probes was obtained using CAFM voltage spectroscopy in the contact mode on a sputtered Pt surface. The results show that the modified probes exhibit a superior spatial resolution and high stability during AFM scans, which provide a significant advancement for CAFM measurements.

While many plasmonic phenomena have been realized by using standard nanoscale synthesis in a single 2-dimensional plane, enhanced functionality should be possible by extending into the third dimens...

This article describes an atomic force microscope (AFM) that can operate in any scanning electron microscope (SEM) or SEM combined with a focused ion-beam (FIB) column. The combination of AFM, SEM imaging, energy-dispersive X-ray spectrometry (EDX), FIB milling, and nanofabrication methods (field-emission scanning probe lithography, tip-based electron beam induced deposition, and nanomachining) provides a new tool for correlative nanofabrication and microscopy. Piezoresistive, thermo-mechanically actuated cantilevers (active cantilevers) are used for fast imaging and nanofabrication. Thus, the AFM with active cantilevers integrated into an SEM (AFMinSEM) can generate and characterize nanostructures in situ without breaking vacuum or contaminating the sample.

An artifact limiting the reproduction of three-dimensional (3D) designs using nanoprinting has been quantified. Beam-induced heating was determined through complementary experiments, models, and simulations to affect the deposition rate during the 3D nanoprinting of mesh objects using focused electron beam induced deposition (FEBID). The mesh objects are constructed using interconnected nanowires. During nanowire growth, the beam interaction driving deposition also causes local heating. The temperature at the beam impact region progressively rises as thermal resistance increases with nanowire growth. Heat dissipation resembles the classical mode of heat transfer from extended surfaces; heat must flow through the mesh object to reach the substrate sink. Simulations reveal that beam heating causes an increase in the rate of precursor desorption at the BIR, causing a concomitant decrease in the deposition rate, overwhelming an increase in the deposition rate driven by thermally enhanced precursor surface diffusion. Temperature changes as small as 10 K produce noticeable changes in deposit geometry; nanowires appear to deflect and curve toward the substrate because the vertical growth rate decreases. The 3D FEBID naturally ensues from the substrate surface upward, inducing a vertical temperature gradient along the deposit. Simulations, experiments, temperature-controlled studies, and process current monitoring all confirm the cause of nanowire distortion as beam-induced heating while also revealing the rate-determining physics governing the final deposit shape.

The Au(I) complexes CF3AuCNMe (1a) and CF3AuCNtBu (1b) were investigated as Au(I) precursors for focused electron beam-induced deposition (FEBID) of metallic gold. Both 1a and 1b are sufficiently volatile for sublimation at 125 ± 1 mTorr in the temperature range of roughly 40–50 °C. Electron impact mass spectra of 1a–b show gold-containing ions resulting from fragmenting the CF3 group and the CNR ligand, whereas in negative chemical ionization of 1a–b, the major fragment results from dealkylation of the CNR ligand. Steady-state depositions from 1a in an Auger spectrometer produce deposits with a similar gold content to the commercial precursor Me2Au(acac) (3) deposited under the same conditions, while the gold content from 1b is less. These results enable us to suggest the likely fate of the CF3 and CNR ligands during FEBID.

It is generally accepted that the low-energy electron beam (e-beam) irradiation has a negligible effect on the physical properties of metallic nanostructures during the in-situ imaging and welding inside the scanning electron microscope. Here, a pronounced decrease in the electrical conductivity of Ag nanowires is obtained after contacting the ends by using the e-beam induced deposition nanolithography. A vivid crystal defect migration inside nanowire is observed under the transmission electron microscope, revealing that the e-beam induced internal stress provides an explanation for the remarkable conductivity decrease. These observations indicate that e-beam exposure can cause anomalous morphology change inside Ag nanowire. In addition, the electrical conductivity provides an effective strategy to monitor the related nanostructure change.

Two multiwalled carbon nanotubes (MWNTs) were seamlessly connected via the crystallization of a bridging amorphous carbon (a-C) joint using a transmission electron microscope. Technically, such a CNT connection involves electron beam induced deposition of amorphous carbon at the gap between the two nanotubes, followed by a controlled Joule heating process. Upon heating, the deposited a-C crystalized into a multi-layer tubular structure that merges into open-ended CNT shells, forming continuous graphitic layers across the junction. For the first time, seamless repairing of a pure MWNT after its electrical breakdown is thus achieved, accompanied by the nearly full recovery of its electrical conductance. More generally, we demonstrated its usage in the seamless joining of any two nanotubes, regardless of their difference in diameter, chirality, shell number and axis orientation. Molecular dynamics calculations reveal more details on how the a-C joint evolves into coherent sp2-bonded networks connecting the given nanotube pairs, thus highlighting the unique ability of the C system to reconstruct itself into any required sp2 graphitic configuration at high temperature. This seamless-joining method can be further extended to the connection between nanotubes and graphene, exhibiting its particular technological importance for building novel sp2 carbon-based nanostructures and devices via the bottom-up approach.

High-fidelity 3D printing of nanoscale objects is an increasing relevant but challenging task. Among the few fabrication techniques, focused electron beam induced deposition (FEBID) has demonstrated its high potential due to its direct-write character, nanoscale capabilities in 3D space and a very high design flexibility. A limitation, however, is the low fabrication speed, which often restricts 3D-FEBID for the fabrication of single objects. In this study, we approach that challenge by reducing the substrate temperatures with a homemade Peltier stage and investigate the effects on Pt based 3D deposits in a temperature range of 5–30&nbsp, °C. The findings reveal a volume growth rate boost up to a factor of 5.6, while the shape fidelity in 3D space is maintained. From a materials point of view, the internal nanogranular composition is practically unaffected down to 10&nbsp, °C, followed by a slight grain size increase for even lower temperatures. The study is complemented by a comprehensive discussion about the growth mechanism for a more general picture. The combined findings demonstrate that FEBID on low substrate temperatures is not only much faster, but practically free of drawbacks during high fidelity 3D nanofabrication.

Non-linear manipulation of light at the nanoscale is increasingly important for quantum optics and photonics. Plasmonic media provide one important workbench for the manipulation of these nonlinearities.1 The design of plasmonic structures typically involves time-consuming, iterative, computer simulations, nanofabrication and characterization with large suites of independent tools. Hence, in-situ fabrication and characterization along with real time design optimization is an appealing option for the development of hybrid quantum nanophotonic devices. Here, we will describe emerging capabilities for in situ electron beam induced deposition (EBID) and cathodoluminescence (CL) microscopy in an environmental SEM. We outline our work writing and characterizing nanoplasmonic structures that exhibit well-defined field localization and multiple tunable resonances over a broad spectrum as part of the development of new high-efficiency nanophotonic nonlinear media. Developing deter- ministic high-quality single photon emitters is an equally important direction for photonic quantum information processing. Due to the sub-nanometer footprint of such emitters, optical methods are often insufficient for local characterization. We describe our efforts to create, manipulate and characterize color centers in 2D and bulk materials such as hBN. We discuss e-beam induced effects for localized defect creation and EBID based control of color centers to allow emission tuning. Cathodoluminescence lifetime and autocorrelation measurements are utilized for sub-diffraction-limited in-situ assessment of the single photon emission properties.

Low-energy electrons are released whenever ionizing high-energy radiation interacts with matter. They drive chemical reactions in the irradiated material, enable state-of-the art nanofabrication technologies such as focused electron beam induced deposition (FEBID), and contribute to the reactions of resist materials in extreme ultraviolet lithography (EUVL). This contribution presents fundamental research on the role of low-energy electrons in FEBID and EUVL. We discuss how reactions initiated by low-energy electrons can be exploited in FEBID to obtain metal-containing deposits with optimal purity. Regarding EUVL, the role of low-energy electrons in the conversion of an inorganic resist by EUV absorption has been investigated.

Focused electron beam induced deposition of pure materials from aqueous solutions has been of interest in recent years. However, controlling the liquid film in partial vacuum is challenging. Here we modify the substrate to increase control over the liquid layer in order to conduct a parametric study of copper deposition in an environmental scanning electron microscope. We identified the transition from electron to mass-transport limited deposition as well as two additional regimes characterized by aggregated and high-aspect ratio deposits. We observe a high deposition efficiency of 1–10 copper atoms per primary electron that is consistent with a radiation chemical model of the deposition process.

Focused electron beam-induced deposition (FEBID) and focused ion beam-induced deposition (FIBID) are direct-write fabrication techniques that use focused beams of charged particles (electrons or ions) to create 3D metal-containing nanostructures by decomposing organometallic precursors onto substrates in a low-pressure environment. For many applications, it is important to minimize contamination of these nanostructures by impurities from incomplete ligand dissociation and desorption. This spotlight on applications describes the use of ultra high vacuum surface science studies to obtain mechanistic information on electron- and ion-induced processes in organometallic precursor candidates. The results are used for the mechanism-based design of custom precursors for FEBID and FIBID.

Seven gold(I) N-heterocyclic carbene (NHC) complexes were synthesized, characterized, and identified as suitable precursors for focused electron beam-induced deposition (FEBID). Several variations on the core Au(NHC)X moiety were introduced, that is, variations of the NHC ring (imidazole or triazole), of the alkyl N-substituents (Me, Et, or iPr), and of the ancillary ligand X (Cl, Br, I, or CF3). The seven complexes were tested as FEBID precursors in an on-substrate custom setup. The effect of the substitutions on deposit composition and growth rate indicates that the most suitable organic ligand for the gold precursor is triazole-based, with the best deposit composition of 15 atom % gold, while the most suitable anionic ligand is the trifluoromethyl group, leading to a growth rate of 1 × 10−2 nm3/e−.

Micro- and nano-patterns are gaining increasing attraction in several fields ranging from nanoelectronics to bioengineering. The mechanical properties of the nanostructures (nanopillars, nanotubes, nanowires, etc.) are highly relevant for many applications but challenging to determine. Existing mechanical characterization methods require mounting the testing setup inside a scanning electron microscope (SEM) and additional sample modification. Here, we propose two atomic force microscopy (AFM) methods, based on contact mode imaging (CMI) and force spectroscopy imaging (FSI), to determine the mechanical characteristics of individual micro- and nanopillars as fabricated, without using SEM. We present the working principles of both methods and two case studies on nanopillars fabricated by additive manufacturing methods: two-photon polymerization (2PP) and electron beam induced deposition (EBID). Various mechanical parameters were determined using CMI and FSI, respectively. For the 2PP nanopillars, we measured the stiffness (13.5 ± 3.2 N/m and 15.9 ± 2.6 N/m), the maximum lateral force (883.0 ± 89.5 nN and 889.6 ± 113.6 nN), the maximum deflection (64.2 ± 13.6 nm and 58.3 ± 14.24 nm), the failure stress (0.3 ± 0.03 GPa and 0.3 ± 0.02 GPa), and the adhesion force (56.6 ± 4.5 µN and 58.6 ± 5.2 µN). For the EBID nanopillars, we measured the failure stress (2.9 ± 0.2 GPa and 2.7 ± 0.4 GPa). The similar results obtained using both techniques confirmed the efficacy and consistency of the methods. The proposed methodologies have the potential of enabling otherwise impossible measurements particularly when the specimens need to be tested under wet conditions, such as patterns for mechanobiological studies.

Extending nanostructures into the third dimension has become a major research avenue in modern magnetism, superconductivity and spintronics, because of geometry-, curvature- and topology-induced phenomena. Here, we introduce Co-Fe nanovolcanoes-nanodisks overlaid by nanorings-as purpose-engineered 3D architectures for nanomagnonics, fabricated by focused electron beam induced deposition. We use both perpendicular spin-wave resonance measurements and micromagnetic simulations to demonstrate that the rings encircling the volcano craters harbor the highest-frequency eigenmodes, while the lower-frequency eigenmodes are concentrated within the volcano crater, due to the non-uniformity of the internal magnetic field. By varying the crater diameter, we demonstrate the deliberate tuning of higher-frequency eigenmodes without affecting the lowest-frequency mode. Thereby, the extension of 2D nanodisks into the third dimension allows one to engineer their lowest eigenfrequency by using 3D nanovolcanoes with 30% smaller footprints. The presented nanovolcanoes can be viewed as multi-mode microwave resonators and 3D building blocks for nanomagnonics., Comment: 5 pages, 4 figures

Platinum coordination complexes have found wide applications as chemotherapeutic anticancer drugs in synchronous combination with radiation (chemoradiation) as well as precursors in focused electron beam induced deposition (FEBID) for nano-scale fabrication. In both applications, low-energy electrons (LEE) play an important role with regard to the fragmentation pathways. In the former case, the high-energy radiation applied creates an abundance of reactive photo- and secondary electrons that determine the reaction paths of the respective radiation sensitizers. In the latter case, low-energy secondary electrons determine the deposition chemistry. In this contribution, we present a combined experimental and theoretical study on the role of LEE interactions in the fragmentation of the Pt(II) coordination compound cis-PtBr2(CO)2. We discuss our results in conjunction with the widely used cancer therapeutic Pt(II) coordination compound cis-Pt(NH3)2Cl2 (cisplatin) and the carbonyl analog Pt(CO)2Cl2, and we show that efficient CO loss through dissociative electron attachment dominates the reactivity of these carbonyl complexes with low-energy electrons, while halogen loss through DEA dominates the reactivity of cis-Pt(NH3)2Cl2.

Media with engineered magnetization are essential building blocks in superconductivity, magnetism and magnon spintronics. However, the established thin-film and lithographic techniques insufficiently suit the realization of planar components with on-demand-tailored magnetization in the lateral dimension. Here, we demonstrate the engineering of the magnetic properties of CoFe-based nanodisks fabricated by the mask-less technique of focused electron beam induced deposition (FEBID). The material composition in the nanodisks is tuned \emph{in-situ} via the e-beam waiting time in the FEBID process and their post-growth irradiation with Ga ions. The magnetization $M_s$ and exchange stiffness $A$ of the disks are deduced from perpendicular ferromagnetic resonance measurements. The achieved $M_s$ variation in the broad range from $720$ emu/cm$^3$ to $1430$ emu/cm$^3$ continuously bridges the gap between the $M_s$ values of such widely used magnonic materials as permalloy and CoFeB. The presented approach paves a way towards nanoscale 2D and 3D systems with controllable and space-varied magnetic properties., Comment: 5 pages, 4 figures

This article belongs to the Special Issue Advances in Magnetic Force Microscopy., The fabrication of nanostructures with high resolution and precise control of the deposition site makes Focused Electron Beam Induced Deposition (FEBID) a unique nanolithography process. In the case of magnetic materials, apart from the FEBID potential in standard substrates for multiple applications in data storage and logic, the use of this technology for the growth of nanomagnets on different types of scanning probes opens new paths in magnetic sensing, becoming a benchmark for magnetic functionalization. This work reviews the recent advances in the integration of FEBID magnetic nanostructures onto cantilevers to produce advanced magnetic sensing devices with unprecedented performance., This research was funded by the Spanish Ministry of Economy and Competitiveness through the projects PID2020-112914RB-100, MAT2017-82970-C2-1-R, MAT2017-82970-C2-2-R and MAT2018-102627-T, BES-2015-072950, the Aragon Regional Government (Construyendo Europa desde Aragón) through the project E13_20R with European Social Fund funding. This work has received funding from the European’s Union Horizon 2020 research and innovation programme under Grant No. 823717-ESTEEM3.

Functional hybrids comprising metallic nanostructures connected and protected by nonmetallic 2D materials are envisioned as miniaturized components for applications in optics, electronics, and magnetics. A promising strategy to build such elements is the direct writing of metallic nanostructures by focused electron beam induced processing (FEBIP) onto insulating 2D materials. Carbon nanomembranes (CNMs), produced via electron-induced crosslinking of self-assembled monolayers (SAMs), are ultrathin and flexible films; their thickness as well as their mechanical and electrical properties are determined by the specific choice of self-assembling molecules. In this work, functionalized CNMs are produced via electron beam induced deposition of Fe(CO)5 onto terphenylthiol SAMs. Clean iron nanostructures of arbitrary size and shape are deposited on the SAMs, and the SAMs are then crosslinked into CNMs. The functionalized CNMs are then transferred onto either solid substrates or onto grids to obtain freestanding metal/CNM hybrid structures. Iron nanostructures with predefined shapes on top of 1 nm thin freestanding CNMs are realized; they stay intact during the fabrication procedures and remain mechanically stable. Combining the ease and versatility of SAMs with the flexibility of FEBIP thus leads to a route for the fabrication of functional hybrid nanostructures. © 2020 The Authors. Published by Wiley-VCH GmbH.

Self-assembly nanofabrication is increasingly appealing in complex nanostructures, as it requires fewer materials and has potential to reduce feature sizes. The use of DNA to control nanoscale and microscale features is promising but not fully developed. In this work, we study self-assembled DNA nanotubes to fabricate gold nanowires for use as interconnects in future nanoelectronic devices. We evaluate two approaches for seeding, gold and palladium, both using gold electroless plating to connect the seeds. These gold nanowires are characterized electrically utilizing electron beam induced deposition of tungsten and four-point probe techniques. Measured resistivity values for 15 successfully studied wires are between 9.3 &times, 10&minus, 6 and 1.2 &times, 3 &Omega, m. Our work yields new insights into reproducible formation and characterization of metal nanowires on DNA nanotubes, making them promising templates for future nanowires in complex electronic circuitry.

The increasing demand for nanoscale magnetic devices requires development of 3D magnetic nanostructures. In this regard, focused electron beam induced deposition (FEBID) is a technique of choice for direct-writing of complex nano-architectures with applications in nanomagnetism, magnon spintronics, and superconducting electronics. However, intrinsic properties of nanomagnets are often poorly known and can hardly be assessed by local optical probe techniques. Here, an original spatially resolved approach is demonstrated for spin-wave spectroscopy of individual circular magnetic elements with sample volumes down to about 10−3 μm3. The key component of the setup is a coplanar waveguide whose microsized central part is placed over a movable substrate with well-separated CoFe-FEBID nanodisks which exhibit standing spin-wave resonances. The circular symmetry of the disks allows for the deduction of the saturation magnetization and the exchange stiffness of the material using an analytical theory. A good correspondence between the results of analytical calculations and micromagnetic simulations is revealed, indicating a validity of the used analytical model going beyond the initial thin-disk approximation used in the theoretical derivation. The presented approach is especially valuable for the characterization of direct-write magnetic elements opening new horizons for 3D nanomagnetism and magnonics.

Focused electron beam induced deposition (FEBID) is a direct-write nanofabrication technique able to pattern three-dimensional magnetic nanostructures at resolutions comparable to the characteristic magnetic length scales. FEBID is thus a powerful tool for 3D nanomagnetism which enables unique fundamental studies involving complex 3D geometries, as well as nano-prototyping and specialized applications compatible with low throughputs. In this focused review, we discuss recent developments of this technique for applications in 3D nanomagnetism, namely the substantial progress on FEBID computational methods, and new routes followed to tune the magnetic properties of ferromagnetic FEBID materials. We also review a selection of recent works involving FEBID 3D nanostructures in areas such as scanning probe microscopy sensing, magnetic frustration phenomena, curvilinear magnetism, magnonics and fluxonics, offering a wide perspective of the important role FEBID is likely to have in the coming years in the study of new phenomena involving 3D magnetic nanostructures.

The next generation optical, electronic, biological, and sensing devices as well as platforms will inevitably extend their architecture into the 3rd dimension to enhance functionality. In focused ion beam induced deposition (FIBID), a helium gas field ion source can be used with an organometallic precursor gas to fabricate nanoscale structures in 3D with high-precision and smaller critical dimensions than focused electron beam induced deposition (FEBID), traditional liquid metal source FIBID, or other additive manufacturing technology. In this work, we report the effect of beam current, dwell time, and pixel pitch on the resultant segment and angle growth for nanoscale 3D mesh objects. We note subtle beam heating effects, which impact the segment angle and the feature size. Additionally, we investigate the competition of material deposition and sputtering during the 3D FIBID process, with helium ion microscopy experiments and Monte Carlo simulations. Our results show complex 3D mesh structures measuring ~300 nm in the largest dimension, with individual features as small as 16 nm at full width half maximum (FWHM). These assemblies can be completed in minutes, with the underlying fabrication technology compatible with existing lithographic techniques, suggesting a higher-throughput pathway to integrating FIBID with established nanofabrication techniques.

Focused Electron Beam Induced Deposition (FEBID) for magnetic tip fabrication is presented in this work as an alternative to conventional sputtering-based Magnetic Force Microscopy (MFM) tips. FEBID enables the growth of a high-aspect-ratio magnetic nanorod with customized geometry and composition to overcome the key technical limitations of MFM probes currently on the market. The biggest advantage of these tips, in comparison with CoCr coated pyramidal probes, lies in the capability of creating sharp ends, nearly 10 nm in diameter, which provides remarkable (topographic and magnetic) lateral resolution in samples with magnetic features close to the resolution limits of the MFM technique itself. The shape of the nanorods produces a very confined magnetic stray field, whose interaction with the sample is extremely localized and perpendicular to the surface, with negligible in-plane components. This effect can lead to a better analytical and numerical modelling of the MFM probes and to an increase in the sensitivity without perturbing the magnetic configuration of soft samples. Besides, the high-aspect ratio achievable in FEBID nanorod tips makes them magnetically harder than the commercial ones, reaching coercive fields higher than 900 Oe. According to the results shown, tips based on magnetic nanorods grown by FEBID can be eventually used for quantitative analysis in MFM measurements. Moreover, the customized growth of Co- or Fe-based tips onto levers with different mechanical properties allows MFM studies that demand different measuring conditions. To showcase the versatility of this type of probe, as a last step, MFM is performed in a liquid environment, which still remains a challenge for the MFM community largely due to the lack of appropriate probes on the market. This opens up new possibilities in the investigation of magnetic biological samples., M. J., E. B. and A. A. acknowledge the support from the Spanish Ministry of Economy and Competitiveness (MINECO) under project nos. MAT2015-73775-JIN and MAT2016-76824-C3-1-R. M. J. and J. G.-H acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through The “María de Maeztu” Programme for Units of Excellence in R&D (MDM-2014-0377). M. J. also acknowledges financial support from the Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid through the project SI1/PJI/2019-00055. J. P.-N., C. M. and J. M. D. T. acknowledge financial support from the Spanish MINECO through the projects MAT2017-82970-C2-1-R, MAT2017-82970-C2-2-R and RED2018-102627-T, from the Aragon Regional Government (Construyendo Europa desde Aragón) through the project E13_20R with European Social Fund funding. This project has received funding from the European's Union Horizon 2020 research and innovation programme under Grant No. 823717-ESTEEM3. J. P.-N. grant is funded by the Ayuda para Contratos Predoctorales para la Formación de Doctores (BES-2015-072950) of the Spanish MINECO with the participation of the European Social Fund.

Recent progress in nano-/micro-fabrication techniques has paved the way for the emergence of synthetic bactericidal patterned surfaces that are capable of killing the bacteria via mechanical mechanisms. Different design parameters are known to affect the bactericidal activity of nanopatterns. Evaluating the effects of each parameter, isolated from the others, requires systematic studies. Here, we systematically assessed the effects of the interspacing and disordered arrangement of nanopillars on the bactericidal properties of nanopatterned surfaces. Electron beam induced deposition (EBID) was used to additively manufacture nanopatterns with precisely controlled dimensions (i.e., a height of 190 nm, a diameter of 80 nm, and interspaces of 100, 170, 300, and 500 nm) as well as disordered versions of them. The killing efficiency of the nanopatterns against Gram-positive Staphylococcus aureus bacteria increased by decreasing the interspace, achieving the highest efficiency of 62 ± 23% on the nanopatterns with 100 nm interspacing. By comparison, the disordered nanopatterns did not influence the killing efficiency significantly, as compared to their ordered correspondents. Direct penetration of nanopatterns into the bacterial cell wall was identified as the killing mechanism according to cross-sectional views, which is consistent with previous studies. The findings indicate that future studies aimed at optimizing the design of nanopatterns should focus on the interspacing as an important parameter affecting the bactericidal properties. In combination with controlled disorder, nanopatterns with contrary effects on bacterial and mammalian cells may be developed.

Two platinum precursors, Pt(CO)2Cl2 and Pt(CO)2Br2, were designed for focused electron beam-induced deposition (FEBID) with the aim of producing platinum deposits of higher purity than those deposited from commercially available precursors. In this work, we present the first deposition experiments in a scanning electron microscope (SEM), wherein series of pillars were successfully grown from both precursors. The growth of the pillars was studied as a function of the electron dose and compared to deposits grown from the commercially available precursor MeCpPtMe3. The composition of the deposits was determined using energy-dispersive X-ray spectroscopy (EDX) and compared to the composition of deposits from MeCpPtMe3, as well as deposits made in an ultrahigh-vacuum (UHV) environment. A slight increase in metal content and a higher growth rate are achieved in the SEM for deposits from Pt(CO)2Cl2 compared to MeCpPtMe3. However, deposits made from Pt(CO)2Br2 show slightly less metal content and a lower growth rate compared to MeCpPtMe3. With both Pt(CO)2Cl2 and Pt(CO)2Br2, a marked difference in composition was found between deposits made in the SEM and deposits made in UHV. In addition to Pt, the UHV deposits contained halogen species and little or no carbon, while the SEM deposits contained only small amounts of halogen species but high carbon content. Results from this study highlight the effect that deposition conditions can have on the composition of deposits created by FEBID.

Performing magnetization studies on individual nanoparticles is a highly demanding task, especially when measurements need to be carried out under large sweeping magnetic fields or variable temperature. Yet, characterization under varying ambient conditions is paramount in order to fully understand the magnetic behavior of these objects, e.g., the formation of nonuniform states or the mechanisms leading to magnetization reversal and thermal stability. This, in turn, is necessary for the integration of magnetic nanoparticles and nanowires into useful devices, e.g., spin-valves, racetrack memories, or magnetic tip probes. Here, we show that nanosuperconducting quantum interference devices based on high critical temperature superconductors are particularly well suited for this task. We have successfully characterized a number of individual Co nanowires grown through focused electron beam induced deposition and subsequently annealed at different temperatures. Magnetization measurements performed under sweeping magnetic fields (up to ∼100 mT) and variable temperature (1.4-80 K) underscore the intrinsic structural and chemical differences between these nanowires. These point to significant changes in the crystalline structure and the resulting effective magnetic anisotropy of the nanowires, and to the nucleation and subsequent vanishing of antiferromagnetic species within the nanowires annealed at different temperatures., This work was partly funded and supported by the Spanish MINECO (MAT2014-51982-C2, MAT2015-73914-JIN, MAT2015-64083-R, MAT2015-69725-REDT, MAT2017-82970-C2-1-R, and MAT2017-82970-C2-2-R), the Aragón Regional Government through projects E26, E09_17R, and E13_17R (Construyendo Europa desde Aragón), COST Action CA16218, COST Project CELINA, and the Deutsche Forschungsgemeinschaft via project KO 1301/13-2. J.P.-N. grant is funded by the Ayuda para Contratos Predoctorales para la Formación de Doctores of the Spanish MINECO (BOE 12/06/15) with the participation of the European Social Fund. B.M. gratefully acknowledges support by the German Academic Scholarship Foundation.

Fabrication of three-dimensional (3D) nanoarchitectures by focused electron beam induced deposition (FEBID) has matured to a level that highly complex and functional deposits are becoming available for nanomagnetics and plasmonics. However, the generation of suitable pattern files that control the electron beam’s movement, and thereby reliably map the desired target 3D structure from a purely geometrical description to a shape-conforming 3D deposit, is nontrivial. To address this issue we developed several writing strategies and associated algorithms implemented in C++. Our pattern file generator handles different proximity effects and corrects for height-dependent precursor coverage. Several examples of successful 3D nanoarchitectures using different precursors are presented that validate the effectiveness of the implementation.

The rapid development of biosensing platforms for highly sensitive and specific detection raises the desire of precise localization of biomolecules onto various material surfaces. Aluminum has been strategically employed in the biosensor system due to its compatibility with CMOS technology and its optical and electrical properties such as prominent propagation of surface plasmons. Herein, we present an adaptable method for preparation of carbon nanoarrays on aluminum surface passivated with poly(vinylphosphonic acid) (PVPA). The carbon nanoarrays were defined by means of electron beam induced deposition (EBID) and they were employed to realize site-specific immobilization of target biomolecules. To demonstrate the concept, selective streptavidin/neutravidin immobilization on the carbon nanoarrays was achieved through protein physisorption with a significantly high contrast of the carbon domains over the surrounding PVPA-modified aluminum surface. By adjusting the fabrication parameters, local protein dens...

Focused electron beam-induced deposition (FEBID) is capable of producing metal-containing nanostructures with lateral resolution on the sub-nanometer scale. Practical application of this nanofabrication technique has been hindered by ligand-derived contamination from precursors developed for thermal deposition methods. Mechanistic insight into FEBID through surface science studies and gas-phase electron-molecule interactions has begun to enable the design of custom FEBID precursors. These studies have shown that precursors designed to decompose under electron irradiation can produce high-purity FEBID deposits. Herein, we highlight the progress in FEBID precursor development with several examples that incorporate this mechanism-based design approach.

Boron-containing materials are increasingly drawing interest for the use in electronics, optics, laser targets, neutron absorbers, and high-temperature and chemically resistant ceramics. In this article, the first investigation into the deposition of boron-based material via electron beam-induced deposition (EBID) is reported. Thin films were deposited using a novel, large-area EBID system that is shown to deposit material at rates comparable to conventional techniques such as laser-induced chemical vapor deposition. The deposition rate and stoichiometry of boron oxide fabricated by EBID using trimethyl borate (TMB) as precursor is found to be critically dependent on the substrate temperature. By comparing the deposition mechanisms of TMB to the conventional, alkoxide-based precursor tetraethyl orthosilicate it is revealed that ligand chemistry does not precisely predict the pathways leading to deposition of material via EBID. The results demonstrate the first boron-containing material deposited by the EBID process and the potential for EBID as a scalable fabrication technique that could have a transformative effect on the athermal deposition of materials.

In the current contribution we present a comprehensive study on the heteronuclear carbonyl complex H2FeRu3(CO)13 covering its low energy electron induced fragmentation in the gas phase through dissociative electron attachment (DEA) and dissociative ionization (DI), its decomposition when adsorbed on a surface under controlled ultrahigh vacuum (UHV) conditions and exposed to irradiation with 500 eV electrons, and its performance in focused electron beam induced deposition (FEBID) at room temperature under HV conditions. The performance of this precursor in FEBID is poor, resulting in maximum metal content of 26 atom % under optimized conditions. Furthermore, the Ru/Fe ratio in the FEBID deposit (≈3.5) is higher than the 3:1 ratio predicted. This is somewhat surprising as in recent FEBID studies on a structurally similar bimetallic precursor, HFeCo3(CO)12, metal contents of about 80 atom % is achievable on a routine basis and the deposits are found to maintain the initial Co/Fe ratio. Low temperature (≈213 K) surface science studies on thin films of H2FeRu3(CO)13 demonstrate that electron stimulated decomposition leads to significant CO desorption (average of 8–9 CO groups per molecule) to form partially decarbonylated intermediates. However, once formed these intermediates are largely unaffected by either further electron irradiation or annealing to room temperature, with a predicted metal content similar to what is observed in FEBID. Furthermore, gas phase experiments indicate formation of Fe(CO)4 from H2FeRu3(CO)13 upon low energy electron interaction. This fragment could desorb at room temperature under high vacuum conditions, which may explain the slight increase in the Ru/Fe ratio of deposits in FEBID. With the combination of gas phase experiments, surface science studies and actual FEBID experiments, we can offer new insights into the low energy electron induced decomposition of this precursor and how this is reflected in the relatively poor performance of H2FeRu3(CO)13 as compared to the structurally similar HFeCo3(CO)12., The authors acknowledge the fruitful and productive environment provided by the COST Action CELINA CM1301 and we would like to take the opportunity to extend our thanks to Prof. Petra Swiderek for running this Action exceptionally well. Marc Hanefeld and Michael Huth acknowledge financial support by the Deutsche Forschungsgemeinschaft (DFG) through Priority Program SPP 1928, project HU 752/12-1. DHF thanks the National Science Foundation for support of this work through the linked collaborative grants CHE-1607621 and CHE-1607547. OI acknowledges supported from the Icelandic Center of Research (RANNIS) Grant No. 13049305(1-3) and the University of Iceland Research Fund. RKTP acknowledges a doctoral grant from the University of Iceland Research Fund and financial support from the COST Action CM1301; CELINA, for short term scientific missions (STSMs).

The use of bimetallic precursors in focused electron beam induced deposition (FEBID) allows mixed metal nanostructures with well-defined metal ratios to be generated in a single step process. HFeCo3(CO)12 is an example of one such bimetallic precursor that has previously been shown to form deposits with unusually high metal content (>80%) as compared to that of typical FEBID deposits (

Background: Focused electron beam induced deposition (FEBID) allows for the deposition of free standing material within nanometre sizes. The improvement of the technique needs a combination of new precursors and optimized irradiation strategies to achieve a controlled fragmentation of the precursor for leaving deposited material of desired composition. Here a new class of copper precursors is studied following an approach that probes some surface processes involved in the fragmentation of precursors. We use complexes of copper(II) with amines and perfluorinated carboxylate ligands that are solid and stable under ambient conditions. They are directly deposited on the surface for studying the fragmentation with surface science tools.Results: Infrared spectroscopy and high-resolution electron energy loss spectroscopy (HREELS) are combined to show that the precursor is able to spontaneously lose amine ligands under vacuum. This loss can be enhanced by mild heating. The combination of mass spectrometry and low-energy electron irradiation (0–15 eV) shows that full amine ligands can be released upon irradiation, and that fragmentation of the perfluorinated ligands is induced by electrons of energy as low as 1.5 eV. Finally, the cross section for this process is estimated from the temporal evolution in the experiments on electron-stimulated desorption (ESD).Conclusion: The release of full ligands under high vacuum and by electron irradiation, and the cross section measured here for ligands fragmentation allow one to envisage the use of the two precursors for FEBID studies.