In this work, thin films of CuZn and CuTiZn alloys were synthesized by magnetron sputter deposition. Their antibacterial activity on the proliferation of Escherichia coli was investigated after incubation during 24 h at 37.0 degrees C by measuring the bacteria solution absorbance at 600 nm. Among tests usually employed in laboratories to evaluate the antibacterial properties of coatings, this one specially characterizes the action of chemical elements dissolved in the solution, i.e. the so-called release killing mechanism. The obtained results are discussed depending on the film chemical composition (in depth and at the surface), microstructure and crystallinity. A good antibacterial activity was found for pure Zn and CuZn films, whereas a rapid degradation was observed as soon as Ti is added, which coincides with the formation of a dense amorphous phase. At close chemical compositions, formation of this stable metallic glass phase seems to be detrimental to the ion release mechanism. This work highlighted that the microstructural and crystalline properties (more or less porous polycrystalline film/ dense, defect free metallic glass) significantly influence the antibacterial properties of such alloy thin films.

30 keV Ga + irradiation-induced changes of magnetic and magneto-optical properties of sputtered Pt/Co/Pt ultrathin trilayers films have been studied as a function of the ion fluence. Out-of-plane magnetic anisotropy states with enhanced magneto-optical effects were evidenced for specific values of cobalt thickness and irradiation fluence. Results obtained after uniform or quasi-uniform focused ion beam irradiation on either out-of-plane or in-plane magnetized sputtered pristine trilayers are compared. Similar irradiation-induced magnetic changes are evidenced in quasi-uniformly focused ion beam or uniformly irradiated films, grown either by sputtering or molecular beam epitaxy. We discuss on plausible common mechanisms underlying the observed effects.

Zero-mode waveguides (ZMWs) are optical nanostructures fabricated in a thin metallic film capable of confining the excitation volume to the zeptoliter range. In this work we describe the batch fabrication of a nanopore-based device, based upon high-resolution arrays of nanopores (of various sizes), which is used to directly measure the passage of DNA. In our method, nanopores are fabricated in ultrathin dielectric films with a deposited gold layer. The gold layer on the device induces a zero mode waveguide illumination at the cis end of the nanopores. The method presented allows for optical detection, in real time, at the level of a single molecule and a single pore. The detection of fluorescently labelled single molecules passing through the pores, measured using an electron multiplying charge coupled device camera, is described. Molecules inside the nanopore were invisible until they reached the volume illuminated by the evanescent field. This fabrication methodology appears to be very promising for the development and batch fabrication of a new generation of nanopore-based sensor devices. (C) 2017 Elsevier B.V. All rights reserved.

Fabrication of nanopores and nanomasks has recently emerged as an area of considerable interest for research applications ranging from optics, to electronics and to biophysics. In this work we evaluate and compare the fabrication of nanopores, using a finely focused gallium beam, in free-standing membranes/films made of Si, SiN, and SiO"2 (having thicknesses of a few tens of nanometers) and also in graphene and hexagonal boron nitride (h-BN) atomically thin suspended sheets. Mechanical resistance, charging effects and patterning performances are evaluated and compared. In spite of the very different properties of the membranes we report that reproducible nanopore fabrication in the sub-10nm range can be achieved in both amorphous and atomically thin sheets using Ga^+ focused ion beams (FIB).

Focused ion beam milling has been applied to fabricate an ultra-thin taper structure on crystalline indium phosphide to realize a multi-wavelength vertical cavity photonic device. The appropriate FIB scanning procedures and operating parameters were used to control the target material re-deposition and to minimize the surface roughness of the milled area. The sputtering yield of crystalline indium phosphide target was determined by investigating the relationship between milling depth and ion dose. By applying the optimal experimentally obtained yield and related dose range, we have fabricated an ultra-thin taper structure whose etch depths are precisely and progressively tapered from 25 nm to 55 nm, with a horizontal slope of about 1:13,000. The optical characterization of this tapered device confirms the expected multi-wavelength behavior of our device and shows that the optical losses induced by the FIB milling process are negligible. (C) 2014 Elsevier B.V. All rights reserved.

We report on the fabrication of fully suspended two-dimensional electron and hole gases in III-V heterostructures. Low temperature transport measurements verify that the properties of the suspended gases are only slightly degraded with respect to the non-suspended gases. Focused ion beam technology is used to pattern suspended nanostructures with minimum damage from the ion beam, due to the small width of the suspended membrane.

We report on the selective creation of spin filtering regions in non-magnetic InGaAs layers by implantation of Ga ions by Focused Ion Beam. We demonstrate by photoluminescence spectroscopy that spin dependent recombination (SDR) ratios as high as 240% can be achieved in the implanted areas. The optimum implantation conditions for the most efficient SDR are determined by the systematic analysis of different ion doses spanning four orders of magnitude. The application of a weak external magnetic field leads to a sizable enhancement of the SDR ratio from the spin polarization of the nuclei surrounding the polarized implanted paramagnetic defects.

Instabilities and strong spatiotemporal fluctuations in out-of-plane demagnetized stripe domain patterns of a Pt/Co(0.5 nm)/Pt film designed by Ga${}^{+}$ ion irradiation were visualized by polar magneto-optical Kerr effect microscopy and studied in the spin reorientation transition temperature region. A two-dimensional-stripe melting transition was evidenced before reaching the in-plane spin state. Slow dynamics were driven by short-range instabilities on magnetic defects which trigger long-range transverse wall fluctuations. The spatial and temporal behavior of stripelike ``floating'' patches was investigated. Dynamics cannot be simply interpreted by models previously proposed for liquid crystals.

In this article we report on carving nanopores into suspended graphene sheets using a finely focused and shaped gallium ion beam. We show that in addition to serving as a nearly ideal substrate for high resolution patterning, suspended graphene can be patterned with high accuracy using a methodology that is described. Furthermore, shapes and dimensions of the fabricated nanopores were investigated, showing stable structures that do not follow the circular shape of the FIB probe. These results highlight the role of preferential engraving directions during the carving process of the graphene material. We conclude in confirming the highly insulating properties of such graphene when immersed in an ionic solution, which is of particular interest for experiments such as DNA translocation.

In this paper, we report on the surface patterning of punctual defects onto graphene films grown on 6H-SiC(0001) substrates, using a finely focused gallium (Ga^+) ion beam. We present organized arrays of nano-defects, designed using ion doses in the range of 10-1x10^6Ga^+ ions/dot. Using Conductive Atomic Force Microscopy (CAFM) and Raman spectroscopy we evidence the strong resilience of graphene towards ion irradiation and characterize the morphology and the electronic properties of the FIB-induced local nano-defects. We show that punctual ion irradiation and dose control allow progressive amorphization of graphene leading to the promising perspective of graphene-based tunable templates.

We use solid-state nanopores to study the dynamics of single electrically charged colloids through nanopores as a function of applied voltage. We show that the presence of a single colloid inside of the pore changes the pore resistance, in agreement with theory. The normalized ionic current blockade increases with the applied voltage and remains constant when the electrical force increases even more. We observe short and long events of current blockades. Their durations are associated, respectively, with low and high current variation. The ratio of long events increases with the electrical force. The events frequency increases exponentially as a function of applied voltage and saturates at high voltage. The dwelling time decreases exponentially at low and medium voltages when the electrical force increases. At large voltages, this time decreases inversely proportionally to the applied voltage. The long events are associated with translocation events. We show that the dynamics of colloids through the nanopore is governed mainly by two mechanisms, by the free-energy barrier at relatively low and medium voltages and by the electrophoresis mechanism at high voltage.

Since its discovery, graphene has attracted tremendous interest and their unusual properties make it a promising candidate for future electronic and optic applications [1. 2]. Along the view of designing graphene-based devices many efforts are devoted to the achievement of large scale graphene patterning in a reproducible way with controlled structural quality [3]. It is also of prior fundamental significance to further control the band gap. Recent theoretical studies demonstrated that antidot lattice can turn semimetalic graphene into a gapped semiconductor, where the size of the gap can be tuned via the geometry of the lattice [4]. The possibility to open band gaps by inducing artificial defects and the ability to control the conductivity by physical means is hence a crucial step in order to establish graphene as a competitive material for future nanoelectronics [5]. Further studies would be important to find a way to produce graphene with desired defects to modify electronic properties [6]. The functionalization is suitable way to detect imperfections in a graphene crystal lattice and to separate natural and arficial defects [7, 8]. We show in this presentation that ultra high resolution Focused ion beam (FIB) is a powerful technique for tailoring tunable defects by irradiation of a graphene sheet. FIB has the unique capability for rapid prototyping since it requires neither mask nor resist while processing [9]. Such direct writing does not require subsequent pattern transformation either. The sub-10 nm spot size achievable by the FIB method enables the patterning of diverse nanostructures at a very high resolution and offers the opportunity to functionalize surfaces with a periodic array of controlled identical extended nanodefects. nanometer scale arrays were fabricated via FIB technology in the low-current processing condition, which is promisingly useful in the construction of various templates using “Few Layer” graphene on 6HSiC(0001). The topography of the graphene surface before and after fabrication of the patterned areas is characterized by atomic force microscopy in tapping mode. Raman spectroscopy is used to study graphene nanostructured with different ion doses. Several examples of patterned graphene will be presented.

Epitaxial graphene on silicon carbide labeled 6H-SiC (0001) substrate has been patterned using high resolution focused ion beam. Atomic force microscopy and Raman spectroscopy measurements give evidence of the strong resilience of the graphene monolayer to ion irradiation. The morphology and electronic properties of defects versus ion doses exhibit a progressive local amorphization of graphene. (C) 2011 American Institute of Physics. [doi:10.1063/1.3628341]

Regular sets of ultranarrow lines have been patterned on a Pt/Co(1.4 nm)/Pt ultrathin magnetic film by focusing a Ga+ ion beam (FIB) at different fluences. Ga+ ion irradiation is known to soften magnetic properties in such films. Even at low Ga+ ion fluence, and as proved by atomic force microscopy, the transverse perturbed region in the lines is much wider than calculated by Stopping and Range of Ions in Matter (SRIM) simulations, demonstrating that a swelling effect superimposes to more localized irradiation damages. Field-induced magnetization reversal and static or dynamic coercivity of these FIB lines separated by nonirradiated ferromagnetic tracks have been investigated by polar MOKE microscopy. The nucleation of small reversed domains is much easier in FIB lines irradiated at high fluence, and a remnant domain structure can be stabilized in that case. The coercive field of the FIB irradiated lines is calculated using a modified one-dimensional-droplet model.

We report on the optimization of a focused gold ion beam source which is used for local and shallow implantation of gold in GaAs wafers. The ion source uses pure liquid gold and the ion optics is designed for high resolution patterning. Imaging and etching performances are evaluated. Then, arrays of implanted gold dots are fabricated at 20keV in GaAs substrates, which are subsequently used for epitaxial growth. Formation of organized GaAs nanowires is observed. Their diameter can be lower than 10nm.

Highly Focused Ion Beams (FIB) are used to produce in one step large quantities of solid state nanopores drilled in thin dielectric films with high reproducibility and well controlled morphologies. We explore both the production of nanopores of various diameters and study their applicability to different biological molecules such as DNA, or folded and unfolded proteins, and then we compare their transport properties. We also report on the translocation of Fibronectin which an original experiment made possible is using the methodology described in this article.

Arrays of ultrathin Pt/Co(0.5 nm)/Pt nano-platelets with lateral sizes ranging from 30 nm to 1 µm have been patterned by focused ion beam (FIB) lithography under a weak Ga(+) ion fluence. From polar magneto-optical Kerr microscopy it is demonstrated that nano-platelets are ferromagnetic with perpendicular anisotropy down to a size of 50 nm. The irradiation process creates a magnetically soft ring at the nano-platelet periphery in which domain nucleation is initiated at a low field. The magnetization reversal in nano-platelets can be interpreted using a confined droplet model. All of the results prove that ultimate FIB patterning is suitable for preparing discrete magnetic recording media or small magnetic memory elements and nano-devices.

Here we propose to detail an innovative FIB instrumental approach and processing methodologies we have developed for sub-10 nm nanopore fabrication. The main advantage of our method is first to allow direct fabrication of nanopores in relatively large quantities with an excellent reproducibility. Second our approach offers the possibility to further process or functionalize the vicinity of each pore on the same scale keeping the required deep sub-10 nm scale positioning and patterning accuracy. We will summarise the optimisation efforts we have conducted aiming at fabricating thin (10-100 nm thick) and high quality dielectric films to be used as a template for the nanopore fabrication, and at performing efficient and controlled FIB nanoengraving of such a delicate media. Finally, we will describe the method we have developed for integrating these “single nanopore devices” in electrophoresis experiments and our preliminary measurements.

In recent years, nanopores nave become an important tool to study the properties of single biomolecules in ionic solutions. The technique is based on the translocation of biomolecules through pores of comparable size, which are recorded as changes in the pore conductance. Among the various topics that can be studied with this technique are DNA unzipping and protein denaturation Various types of nanopores are used for these experiments, including biological, chemical, and solid‐state pores. Here we present a way to fabricate sub‐5‐nm pores in 20–100 nm thick SiC membranes by direct drilling with a focused ion beam. In order to obtain a user‐friendly setup allowing low‐noise measurements, these membranes have to be carefully integrated into an electrolytic cell. For this purpose, the membranes are fixed on a piece of Pyrex containing a micrometer‐sized aperture, which is used to select the desired pore and at the same time reduces the area of the membrane that is exposed to the liquid, thus reducing the capacitance and the noise of the system.

Coherent x-ray diffractive imaging is a powerful method for studies on nonperiodic structures on the nanoscale. Access to femtosecond dynamics in major physical, chemical, and biological processes requires single-shot diffraction data. Up to now, this has been limited to intense coherent pulses from a free electron laser. Here we show that laser-driven ultrashort x-ray sources offer a comparatively inexpensive alternative. We present measurements of single-shot diffraction patterns from isolated nano-objects with a single 20 fs pulse from a table-top high-harmonic x-ray laser. Images were reconstructed with a resolution of 119 nm from the single shot and 62 nm from multiple shots.