Sparsely distributed and self-organized gold-nanocones are fabricated by broad argon ion beam sputtering on the gold surface with grazing incident angle. The rotation of the sample with respect to the vertical axis has found to influence the morphology of the obtained nanostructures. Ion beam irradiation of the sample leads to formation of nanoripples when the sample is held stationary, otherwise nanocones are formed if the sample is rotated during irradiation. A hybrid gold-nanocone/graphene/gold-nanohole based surface-enhanced Raman scattering (SERS) sensor is proposed and shown to exhibit an enhancement factor of 109 via finite-difference time-domain (FDTD) simulations.

Single photon sources (SPS) are an important building block for realizing quantum technologies for computing, communication, and sensing. For industrialization, electrically controllable color centers acting as SPS are required. We have demonstrated the creation of electrically controllable silicon vacancies (VSis) in the SiC pn junction diode fabricated by proton beam writing (PBW). PBW was successfully used to introduce electrically controllable VSi without degradation of the diode performance. The dependence of the electroluminescence (EL) and photoluminescence (PL) intensities from VSi on H+ fluence revealed that the emission efficiency of EL is less than that of PL. For EL, the supply of carriers (electrons and/or holes) was restricted due to the resistive region around each VSi introduced by PBW. The results suggest that further improvement in the VSi creation process without defects acting as majority carrier removal centers (highly resistive region) and nonradiative centers by optimization of PBW conditions are key points to realize highly sensitive quantum sensors using VSi.

In this report, we demonstrate the use of helium ion milling for the controllable fabrication of nanostructures in few-layer hexagonal boron nitride (h-BN). Using the direct-write lithographic capabilities of a scanning helium ion microscope (HIM), nanopores with diameters as small as 4 nm and nanoribbons with widths of 3 – 10 nm are etched from suspended h-BN sheets. This ability to pattern h-BN sheets with high-throughput and sub-10 nm precision paves the way for future studies that make use of atomically-thin, nanostructured insulators such as those needed for nanopore sequencing and patterned van der Waals heterostructures.

This work deals with SU-8 waveguides and waveguide structures fabricated on an oxidized silicon substrate using ‘Focused ion beam (FIB) lithography’. From our experimentation it seems that FIB method is practically not suitable for fabricating long SU-8 waveguide structures, rather it is more suitable for nanoscale modification of already fabricated waveguides, such as, to fabricate photonic crystal structures.

We investigate the feasibility of inert ion beam etch (IBE) for subtractive patterning of ReRAM-type structures. We report on the role of the angle-dependent ion beam etch rates in device area control and the minimization of sidewall re-deposition. The etch rates of key ReRAM materials are presented versus incidence angle and ion beam energy. As the ion beam voltage is increased, we demonstrate a significant enhancement in the relative etch rate at glancing incidence (for example, by a factor of 2 for HfO2). Since the feature sidewall is typically exposed to glancing incidence, this energy-dependence plays a role in optimization of the feature shape and in sidewall re-deposition removal.

We present results of SRIM simulations to estimate depth of ion-bombardment damage to the TMO sidewall. Damage is minimized by minimizing ion energy; its depth can be reduced by roughly a factor of 5 over typical IBE energy ranges. For example, ion energies of less than ∼250 eV are indicated to maintain damage below ∼1nm. Multi-angle and multi-energy etch schemes are proposed to maximize sidewall angle and minimize damage, while eliminating re-deposition across the TMO. We utilize 2-D geometry/3-D etch model to simulate IBE patterning of tight-pitched ReRAM features, and generate etched feature shapes.

Al3Nb is known as a high oxidation resistant material, while it is quite brittle. As the fracture toughness of Al3Nb single crystal and its dependence on the composition are not obtained, the micro-sized fracture testing proposed by Suzuki et al. was performed. Al3Nb single crystal micron-order size cantilevers with a chevron-notch were fabricated in a grain of two-phase polycrystalline alloys by using FIB (Focused Ion Beam). From the load-displacement curves during the bending by a nanoindenter, the average value of fracture toughness of Nb-rich Al3Nb is evaluated to be 2.90 MPam1/2, while the fracture toughness of Al-rich Al3Nb is also evaluated to be 2.82 MPam1/2. From this result, the fracture toughness of Al3Nb is less dependent on its Al/Nb ratio. Furthermore the fracture toughness of Al3 (Nb, V) was evaluated to be 2.82 MPam1/2.The fracture toughness of Al3Nb is seemingly insensitive to V addition.

The aim of this study was the synthesis of hard and low-abrasive novel implant materials with built-in time-dependent antibacterial properties, which can be tailored by a well-defined time-dependent and finite release of metal ions. We were able to synthesize such smart implant surfaces employing ECR (electron cyclotron resonance)-plasma on typical titanium implant material by transforming a polymer film into diamond-like carbon (DLC) which contains metal nanoparticles as reservoirs for controlled metal ion release. We found that the amount of released antibacterial metal ions is a biexponential function of time with a high release rate during the first few hours followed by a decreased ion release rate within the following days. To describe our experimental findings, we developed a kinetic model assuming that both nanoparticles near the surface and nanoparticles in the DLC bulk contribute to the total amount of ions released with different time constants.

The variation of the electrical and optical properties under 150 keV Ar+ ion irradiation has been studied in Ge2Sb2Te5 polycrystalline films, either in the rocksalt or in the trigonal structure, by in situ reflectivity measurements and ex situ resistance measurements. As the irradiation dose increases, the disorder introduced in the crystalline films increases and the reflectivity decreases, down to a minimum value that corresponds to complete amorphization. Large differences are found by changing the irradiation temperature, for the two crystalline structures. Indeed, the measured amorphization threshold is the same for the two crystalline phases and equal to 1x1013 cm-2 under irradiation at 77K, whilst at room temperature the trigonal phase requires a dose almost double than the rocksalt phase to be amorphized. By structural analyses we found that, before amorphization, ion irradiation induces a transition from the trigonal to the rocksalt structure. The van der Waals gaps present in the trigonal phase might act as preferential sinks for the displaced and mobile atoms, thus promoting this transition. By further increasing the irradiation dose the formed disordered rocksalt phase converts into the amorphous phase. Ion irradiation also affects the electrical properties of the material: the disorder modifies the temperature dependence of resistance of the trigonal Ge2Sb2Te5 and induces a change of sign (from metallic to insulating behavior) at a dose of 2x1013 cm-2, well below the amorphization threshold.

Surface smoothing of Ru used as underlayer of magnetic tunneling junctions (MTJ)in magneto-resistive random access memory (MRAM) was carried out with gascluster ion beam (GCIB) in order to improve device characteristics. For Rufilms, surface smoothing with 5 kV N2-GCIB irradiation was effective,and CoFe films deposited on smoothed Ru surface also showed smooth surface. Fromthe hysteresis loop measurements of MTJ formed on smoothed Ru withN2-GCIB, it showed improvement of inter-layer coupling magnetic field(Hin) with decreasing the surface roughness of underlayer Ru. Itis expected that surface roughness of MgO in MTJ was also improved by smoothingof underlayer Ru with N2-GCIB.

Silver nanostructures are directly grown on the apex of commercially available silicon AFM probes using our area-selective electroless deposition: the apex of a silicon AFM probe is irradiated using a focused ion beam (FIB), and then the FIB-irradiated AFM probe is exposed to a pure AgNO3 aqueous solution. With this method, a silver nanostructure selectively grows on the tip apex where the native oxide layer has been removed in response to FIB irradiation. Silver ions are reduced by the electrons flowing from the silicon probes into the solution through the FIB-irradiated area owing to the difference in Fermi energy between silicon and the solution. The morphology of the growing silver depends on the concentration of both AgNO3 and the electrons. The growth of a gold nanoflower is also demonstrated on the apex of a silicon AFM probe.

Fe K-edge X-ray absorption spectroscopy (XAS) was applied to study the structural response of iron phosphate glasses to atomic displacements arising from ion beam irradiation, as an analogue of α-recoil damage arising from actinide immobilization. Analysis of XAS spectra demonstrated reduction of Fe3+ to Fe2+ as a consequence of 2 MeV Kr+ and 2 MeV Au+ implantation to a fluence of 2 x 1016 ions / cm2 and 5 x 1015 ions / cm2, respectively.

Carbon Nanotubes (CNTs) exhibit exceptional properties in terms of high strength-to-weight, high electrical conductivity, and high thermal conductivity, and have been employed as a reinforcement in various composites and other materials. Their tolerance to radiation environments may be suggested by their response to energetic ion bombardment. We discuss the effects of argon ion bombardment of both thin and thick multiwall carbon nanotube films over a range of 4 to 11 keV at fluence levels up to the order of 1021 ions/cm2. While individual carbon atoms are readily displaced from a carbon nanotube by bombardment at these energies, these nanotubes also exhibit a self-healing capability. At moderate energies and fluence, if two or more carbon nanotubes are touching and an ion strikes this point, they heal together where a junction or cross-link between them is created and the nanotubes interpenetrate. Even though some of the properties of the carbon nanotubes may be degraded by ion bombardment at non-junction regions, we have demonstrated a bulk cross-linked thin film of randomly oriented multiwall carbon nanotubes with an isotropic thermal conductivity of 2150 W/m K. At higher energies and fluence, the carbon nanotubes appear to collapse and reform aligned parallel to the incoming ion bombardment trajectory, producing high aspect ratio tapered structures. These structures are, in general, fully dense, unlike the loosely packed random carbon nanotube array from which they originated. There is also a sharp transition at the base of these structures from the dense form to the loose-packed form, suggesting that these structures may inhibit further penetration of the energetic ions.

Sapphire is best known for its hardness that makes it ideal for many mechanical and optical applications, but its resistance to radiation damage and its optical properties, combined with metallic nano-particles, make it promising for future opto-electronic and plasmonic devices. In this paper, we present an overview of our work on the fabrication of metallic nano-particles embedded in synthetic sapphire by means of ion implantation, thermal annealing and high energy ion irradiation. We show that we can have control over the amount and size of the nano particles formed inside the matrix by carefully choosing the parameters during the preparation process. Furthermore, we show that anisotropic nano particles can be obtained by an adequate high energy ion irradiation of the originally spherical nano particles. We also have studied the linear and non-linear optical properties of these nano-composites and have confirmed that they are large enough for future applications.

Over the last few years, significant improvements in sources, columns, detectors, control software, and accessories have enabled a wealth of new focused ion beam applications. In addition, modeling has provided many insights into ion-sample interactions and the resultant effects on the sample. With the knowledge gained, the community has found new ion-beam induced chemistries and ion-beam sources, allowing extending nanostructure fabrication and material deposition to smaller dimensions and better control for direct write and patterning. Insignificant proximity effects in resist-based ion beam lithography, combined with the availability of sub-nm ion spot sizes, opens the way to sub-10 nm structures and dense patterns. Additionally, direct-write ion beam nanomachining can process multilevel structures with arbitrary depths in one single process step, with all the information included in a single standard design file, thus enabling fabrication applications not achievable with any other technique.

This article reviews recent developments and applications of two beam systems (focused ion beam [FIB] and scanning electron microscope [SEM]) for in situ characterization and manipulation of material at the micro- and nanoscale. In these applications, the sample may be manipulated, ion milled, mechanically or electrically excited, and its temperature varied from above room temperature to cryogenic levels. FIB-SEM instruments offer new opportunities for in situ characterization by enabling localized exposure of surface layers within the high vacuum microscope chamber environment (especially in conjunction with cryogenic cooling of the bulk sample), through experiments that require either highly accurate material removal or localized material addition through beam-induced gas deposition, and by using micro- and nano-manipulation technologies for probing or positioning. This article describes the current state of the art of this experimental methodology and provides case studies in the areas of cryogenic, electrical, and mechanical characterization.

The combined focused ion beam/scanning electron microscopy/energy dispersive X-ray spectroscopy (FIB/SEM/EDX) system is a novel tool for the automotive catalysis field. Automotive emissions such as SOx, NOx, and particulate matter (PM) are regulated to various extents throughout the world, requiring the use of multiple aftertreatment components such as the diesel particulate filter (DPF), diesel oxidation catalyst (DOC), three-way catalytic converter (TWC), Lean NOx trap (LNT) and selective catalytic reduction (SCR). While these aforementioned aftertreatment components are generally multifunctional and robust in design, thermal and chemical aging over the components’ useful lifetimes results in significantly degraded performance leading to increased engine emissions levels and decreased fuel economy. While the component sizes themselves are generally large (10s of cm to ≈1/2 m), component aging mechanisms usually dominate on the nm-µm scales. In particular, this study has used the FIB/SEM/EDX system to investigate the aging of the diesel particulate filter (DPF) due to engine lubricant-derived inorganic ash accumulation. The FIB/SEM/EDX system has been used in the automotive aftertreatment field for the first time with many surprising and significant findings. Although the samples used in this study are quite different to those typically found in FIB studies, the authors have shown that the FIB/SEM/EDX system is a valuable tool in this research area, especially for the investigation of µm-size intra-particle structure and nm-µm interfacial/sub-surface details around the aged catalyst surface.

Among the exceptional properties of isolated individual carbon nanotubes (CNTs), exceptional thermal conductivity along their axis has been demonstrated, However they have also shown poor thermal transfer between adjacent CNTs. Thick bundles of aligned CNTs have been used as heat pipes, but the thermal input and output power densities are the same, providing no heat spreading effect. We demonstrate the use of energetic argon ion beams to join overlapping CNTs in a thin film to form an interpenetrating network with an isotropic thermal conductivity of 2150 W/m K. Such thin films may be used as heat spreaders to enlarge the thermal footprint of laser diodes and CPU chips, for example, for enhanced cooling. At higher ion energies and fluence, the CNTs appear to collapse and reform, aligned parallel to the ion beam axis, and form dense high aspect ratio tapered structures. The high surface area of these structures lends themselves to applications in energy storage, for example. We consider the mechanisms of energetic ion interaction with CNTs and junction formation of two overlapping CNTs during the subsequent self-healing process, as well as the formation of high aspect ratio structures under more extreme conditions

Spherical submicrometer-sized silica particles were prepared by the sol-gel method and deposited as a monolayer onto silicon wafers, in order to use them as a mask to create regular arrays of nanoscale surface features. Thus, by e-gun evaporation of a 50 nm thick Ag film through the silica mask, Ag nanostructures were obtained after removal of the silica monolayer. In order to tailor the mask characteristics (size and interparticle spacing), the silica masks were irradiated at room temperature with 4 and 6 MeV Si ions at different fluences up to 5×1015 ion/cm2, perpendicularly to the sample surface. After the irradiation the silica particles turned into oblate particles, as a result of the increase of the particle dimension perpendicular to the ion beam and the decrease in the parallel direction. By this way, the mask openings of the silica particle monolayer were modified as a function of the irradiation parameters, and the subsequent Ag e-gun evaporation allowed the formation of ordered arrays of Ag features. The size, shape and interparticle spacing of both the silica particles and the Ag deposits were determined by scanning electron microscopy.

Thanks to an original approach based on the carburization of silicon nanowires, silicon carbide-based one dimensional nanostructures – SiC nanotubes, Si-SiC core-shell nanowires and SiC nanowires – have been synthesized. The original process, which relies on controlling the out-diffusion of Si atoms through SiC, can be monitored by the temperature, the pressure and the time of carburization. These SiC-based 1D nanostructures have been characterized by SEM, FIB-SEM and TEM microscopies and also Raman spectroscopy. Bio-nano-sensors, nano-Field-Effect-Transistors (nano-FETs) or gas sensors may be some applications for these nanostructures.

Silicon nanowires are becoming more important because of increasing requirements of the small scale and dense integration of devices. We report a top-down fabrication method for silicon nanowires using high-energy ion beam irradiation of bulk p-type silicon followed by electrochemical etching. Silicon nanowires with a diameter of ∼50nm have been fabricated and densely patterned nanowire arrays fabricated in different resistivity silicon wafers. With a suitable support structure, free standing silicon nanowires are also achieved. We investigate results depending on silicon wafer resistivity and location within the irradiated area.