Ion Beam Irradiation Research Articles

Spin-Wave Optics in YIG Realized by Ion-Beam Irradiation.

Direct focused-ion-beam writing is presented as an enabling technology for realizing functional spin-wave devices of high complexity, and demonstrate its potential by optically-inspired designs. It is shown that ion-beam irradiation changes the characteristics of yttrium iron garnet films on a submicron scale in a highly controlled way, allowing one to engineer the magnonic index of refraction adapted to desired applications. This technique does not physically remove material, and allows rapid fabrication of high-quality architectures of modified magnetization in magnonic media with minimal edge damage (compared to more common removal techniques such as etching or milling). By experimentally showing magnonic versions of a number of optical devices (lenses, gratings, Fourier-domain processors) this technology is envisioned as the gateway to building magnonic computing devices that rival their optical counterparts in their complexity and computational power.

Texturization of polycrystalline titanium surfaces after low-energy ion-beam irradiation: Impact on biocompatibility

In this study, the impact of low-energy (1 keV) Ar+ ion-beam irradiation on the morphology of polycrystalline Ti disks was investigated. Targets were prepared by cutting and mechanically polishing commercial rods. The surface topographies before and after irradiation were characterized by scanning electron microscopy (SEM) and mechanical profilometry. Irradiation was performed using a wide range of incident angles (αi) from normal to grazing geometries at a total dose of 1018 ions/cm2. SEM analysis of the irradiated Ti targets revealed clear texturing with various attainable surface morphologies depending on αi. The surface features varied from ripples within patches with fingerprint-like patterns (0 ≤ αi ≤ 60°) to oriented structures parallel to the direction of the ion beam, such as pillar/tip structures (65 ≤ αi ≤ 75°) and shallow ripples (αi ≈ 80°). This morphological selectivity could be attributed to the competitive diffusive and erosive regimes, where the lateral uniformity of the morphology was affected by the limited size of the crystal grains. Finally, the wettability and biocompatibility of the characteristic topographies were evaluated, and the results indicated improved performance of the ion-beam-textured surfaces compared to the untreated ones.

Model experiments with Auger electron and X-ray photoelectron spectroscopy at lithiated graphite material: Surface changes related to ion- and electron-beam effects

Li-based batteries as a key element for green energy economy should be permanently improved in their performance. Therefore, the complex electrochemical processes in such batteries have to be understood in detail. For their characterization beside (electro-)chemical methods also electron spectroscopic methods such as X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) are used to get more insight into the chemical processes at the surfaces. One crucial point is stability of the solid electrolyte interface (SEI) upon measurements, especially at the (graphite-)anodes. In this paper, we use highly oriented pyrolytic graphite (HOPG) as a model anode material, which was lithiated in a molten metal intercalation process. Strong beam damage effects at the lithiated HOPG under electron and ion beam radiation are observed and described. These effects are important for using of local electron beam investigations and sputter depth profiling, often applied also for SEI characterization.

Genome-wide analysis of mutations induced by carbon ion beam irradiation in cotton.

Carbon ion beam (CIB) irradiation is a powerful way to create mutations in animals, plants, and microbes. Research on the mutagenic effects and molecular mechanisms of radiation is an important and multidisciplinary issue. However, the effect of carbon ion radiation on cotton is uncertain. In this study, five different upland cotton varieties and five CIB doses were used to identify the suitable irradiation dose for cotton. Three mutagenized progeny cotton lines from the wild-type Ji172 were re-sequenced. The effect of half-lethal dose on mutation induction indicated that 200 Gy with LETmax of 226.9 KeV/μm was the most effective heavy-ion dose for upland cotton and a total of 2,959-4,049 single-base substitutions (SBSs) and 610-947 insertion-deletion polymorphisms (InDels) were identified among the three mutants by resequencing. The ratio of transition to transversion in the three mutants ranged from 2.16 to 2.24. Among transversion events, G:C>C:G was significantly less common than three other types of mutations (A:T>C:G, A:T>T:A, and G:C>T:A). The proportions of six types of mutations were very similar in each mutant. The distributions of identified SBSs and InDels were similar with unevenly distributed across the genome and chromosomes. Some chromosomes had significantly more SBSs than others, and there were "hotspot" mutation regions at the ends of chromosomes. Overall, our study revealed a profile of cotton mutations caused by CIB irradiation, and these data could provide valuable information for cotton mutation breeding.

Electrically Driven Sub-Micrometer Light-Emitting Diode Arrays Using Maskless and Etching-Free Pixelation.

For decades, group-III-nitride-based light-emitting diodes (LEDs) havebeen regarded as a light emitting source for future displays by virtue of their novel properties such as high efficiency, brightness, and stability. Nevertheless, realization of high pixel density displays is still challenging due to limitations of pixelation methods. Here, a maskless and etching-free micro-LED (µLED) pixelation method is developed via tailored He focused ion beam (FIB) irradiation technique, and electrically driven sub-micrometer-scale µLED pixel arrays are demonstrated. It is confirmed that optical quenching and electrical isolation effects are simultaneously induced at a certain ion dose (≈1014 ions cm-2 ) without surface damage. Furthermore, highly efficient µLED pixel arrays at sub-micrometer scale (square pixel, 0.5µm side length) are fabricated. Their pixelation and brightness are verified by various optical measurements such as cathodo-, photo-, and electroluminescence. It is expected that the FIB-induced optical quenching and electrical isolation method can pioneer a new defect engineering technology not only for µLED fabrication, but also for sub-micrometer-scale optoelectronic devices.

Luminescence imaging of helium ions during irradiation to water and to an acrylic block

Although the luminescence images of water and an acrylic block during irradiation of proton and carbon ion beams were measured recently, they were not measured for helium ions. Because the mass of helium ions is four times that of protons and one-third that of carbon ions, different results from protons or carbon ions will be obtained by luminescence imaging. We measured the luminescence images of water and an acrylic block during irradiation of helium ion beams. Imaging was conducted using a cooled charge-coupled device (CCD) camera during the irradiation of helium ion pencil beams at three different energies to a water phantom and an acrylic block in addition to mini-beams of helium ions at four different energies. From the measured luminescence images during irradiation of helium ion pencil beams, we could estimate the ranges of the beams for water and the acrylic block. In the luminescence images of the acrylic block during irradiation of mini-beams of helium ions, we observed the luminescence of mini-beams with Bragg peaks in the images. Luminescence imaging of water and an acrylic block during the irradiation of helium ion beams was possible and could be used for range determination of the beams.

SERS Detection of Rhodamine-6G on Ion Beam Nanostructured Ultra-Thin Gold (Au) Films: A Correlation between Fractal Growth, Water Contact-Angle and Raman Intensity

SERS (Surface Enhanced Raman Scattering) detection of rhodamine-6G on gold nanostructures (Au–NS) of various sizes under ion beam irradiation is presented. On a glass substrate, Au thin films of different thicknesses (∼2, 3 and 5 nm) were deposited by thermal evaporation. Subsequent irradiation using 10 keV Ar+ at different fluences has been able to modify the size of Au-NS. Ion beam-induced sputtering and diffusion processes control the formation of Au-NS. The reduction in Au content during ion beam sputtering is confirmed by Rutherford Backscattering Spectroscopy (RBS), which also validates tuning the size and structures of Au-NS. The wettable characteristics of Au-NS surfaces are controlled by two competing statistical factors of sputtering and surface diffusion. A correlation between the water contact angle, rms roughness, and the detection of rhodamine-6G (R6G) by SERS is presented. The current study sheds light on the mechanism(s) of SERS chemical detection for wider metallic surfaces.

Ion-beam radiation-induced Eshelby transformations: The mean and variance in hydrostatic and shear residual stresses

Ion beam plays a pivotal role in ion implantations and the fabrication of nanostructures. However, there lacks a quantitative model to describe the residual stresses associated with the ion-beam radiation. Radiation-induced residual stress/transformation strain have been mostly recognized in the hydrostatic sub strain space. Here, we use molecular dynamics (MD) simulations to show that the response of a material to irradiation is generally anisotropic that depends on the ion-beam direction, and should be described using tensorial quantities. We demonstrate that accelerator-based ion beam irradiation, combined with the intrinsic lattice anisotropy and externally induced anisotropy (such as anisotropic mechanical loadings), causes radiation-actuated shear transformation strains in addition to hydrostatic expansion. We map out these complex correlations for several materials. Radiation-induced defects are shown to be responsible for residual shear stresses in the manner of Eshelby inclusion transformation. We propose such tensorial response model should be considered for accurate nanoscale fabrication using ion-beam irradiation.

Mechanical Properties of Twisted Carbon Nanotube Bundles with Carbon Linkers from Molecular Dynamics Simulations.

The manufacturing of high-modulus, high-strength fibers is of paramount importance for real-world, high-end applications. In this respect, carbon nanotubes represent the ideal candidates for realizing such fibers. However, their remarkable mechanical performance is difficult to bring up to the macroscale, due to the low load transfer within the fiber. A strategy to increase such load transfer is the introduction of chemical linkers connecting the units, which can be obtained, for example, using carbon ion-beam irradiation. In this work, we investigate, via molecular dynamics simulations, the mechanical properties of twisted nanotube bundles in which the linkers are composed of interstitial single carbon atoms. We find a significant interplay between the twist and the percentage of linkers. Finally, we evaluate the suitability of two different force fields for the description of these systems: the dihedral-angle-corrected registry-dependent potential, which we couple for non-bonded interaction with either the AIREBO potential or the screened potential ReboScr2. We show that both of these potentials show some shortcomings in the investigation of the mechanical properties of bundles with carbon linkers.

The effect of the surface patterning by ion beam irradiation on the Ag directional outflow in Ag/AlN nano-multilayers

Surface templating of nano-multilayers is a promising step for the advanced industrial application of these nanomaterials. In the present work, the effect of focused ion beam modification of Ag/AlN nano-multilayer near-surface region on the Ag surface outflow is revealed. Surface patterning by ion beam irradiation leads to the formation of a higher amount of Ag crystals in relation to the intact surface region. Heat treatment initiates grooving of Ag grain boundaries, resulting in the formation of channels in the nano-multilayer volume. These channels act as pathways for mass transport of Ag to the film surface. Ion bombardment creates regions of high concentration of non-equilibrium defects, which locally increase the driving force for grooving and channeling, thereby promoting creation of more pathways for Ag surface migration. The obtained experimental results indicate that surface modification by focused ion beam can be used for production of nano-multilayers with designed templates of surface outflow.

In-situ, real-time investigation of the formation of oxygen-containing rare-earth hydrides by combining a quartz crystal microbalance and ion beam analysis

We present an in-situ and real-time investigation of the formation of YHO and GdHO thin films grown by reactive e−-beam evaporation. Mass changes were continuously monitored during deposition, oxidation, and illumination using a highly sensitive quartz crystal microbalance, while changes in chemical composition and depth profiles were investigated simultaneously by ion beam analysis. Results highlight the strong reactivity of freshly deposited YHx and GdHx films, even under ultra-high vacuum conditions. Oxidation starts at the surfaces of the films and the oxidation rate is strongly dependent on the O2 pressure. The response of the system under ion beam irradiation and in-situ illumination is also presented and discussed. For the measured mass changes, a quantitative agreement better than 2% was observed between both techniques and demonstrates the consistency and sensitivity of this approach.

Recent progresses on ion beam irradiation induced structure and performance modulation of two-dimensional materials.

Two-dimensional (2D) materials are receiving significant attention for both fundamental research and industrial applications due to their unparalleled properties and wide application potential. In this case, the controllable modulation of their structures and properties is essential for the realization and further expansion of their applications. Accordingly, ion beam irradiation techniques, with large scope to adjust parameters, high manufacturing resolution, and a series of advanced equipment being developed, have been demonstrated to have obvious advantages in manipulating the structure and performance of 2D materials. In recent years, many research efforts have been devoted to uncovering the underlying mechanism and control rules regarding ion irradiation induced phenomena in 2D materials, aiming at fulfilling their application potential as soon as possible. Herein, we review the research progress in the interaction between energetic ions and 2D materials based on the energy transfer model, type of ion source, structural modulation, performance modification of 2D materials, and then their application status, aiming to provide useful information for researchers in this field and stimulating more research advances.

Simulation of Material Sputtering and Gallium Implantation during Focused Ion Beam Irradiation of a Silicon Substrate

Simulation of Material Sputtering and Gallium Implantation during Focused Ion Beam Irradiation of a Silicon Substrate

Моделирование распыления многослойных подложек фокусированным ионным пучком

The level set method was generalized for simulating the evolution of the surface of multilayer substrates under focused ion beam irradiation. For a correct description of such process the calculations took into account the sputtering yield angular dependences, the densities of the irradiated materials and it was considered that sputtered atoms can escape from different layers of the substrate. Comparison of the calculation results with experimental data for test structures formed in a two-layer silicon dioxide–crystalline silicon substrate showed that the developed simulation method makes it possible to predict the shape of structures fabricated by a focused ion beam with good accuracy.

Design and simulation of a low-energy single ion irradiation system for micro/nano-biosample investigation

A low-energy single ion irradiation system is developed in its initiation in Thailand to follow one of the trends in novel ion beam technology exploitation. Single ion irradiation of materials is a highly technological development of ion beam technology. The developed single ion irradiation systems worldwide are primarily in the MeV-energy range and for single cell studies, and recently the trend has been extended to the low-energy range (< 100 keV) but focused on microelectronic applications. Based on our previous research on low-energy ion beam irradiation of biological cells and DNA, we design and simulate a low-energy single ion implantation system, aiming at eventual construction of such a novel ion beam apparatus for applications to the biological studies. In the system, the ion energy is decreased to orders < 1 keV by the existing deceleration lens, then the low-energy ion beam passes through µm slits, and finally, low-energy single ions are obtained by beam scanning with appropriate frequencies from scanner plates and detected by a single ion detection device. Conceptual design, calculation and simulation of this single ion system are presented.

60 MeV Si ion beam irradiation induced modifications in the structural and optical properties of Li doped NiO thin films

Li doped NiO films grown on FTO substrates through spin coating technique were irradiated using 60 MeV Si ions. The films were investigated via several approaches including grazing incidence X-ray diffraction, attenuated total reflectance-Fourier transform infrared spectroscopy, atomic force microscopy, micro-Raman and UV–visible spectroscopy. The crystalline nature of films declines with the initial face-centered cubic structure for 1x1014 ions cm−2 owing to the energy loss of Si ions in a Li doped NiO (Li:NiO) lattice during the generation of defects. The crystallite size of samples was evaluated using Scherrer’s equation. The vibrational modes were investigated via micro-Raman analysis. AFM topography was recorded for pristine and Si ion irradiated films. The ion fluence of Si ion in the used energy range lowers the transmittance Li:NiO films as compared to the pristine.

Simulation of focused ion beam milling of multilayer substrates

The level set method was generalized for simulating the evolution of the surface of multilayer substrates under focused ion beam irradiation. For a correct description of such process the calculations took into account the sputtering yield angular dependences, the densities of the irradiated materials and it was considered that sputtered atoms can escape from different layers of the substrate. Comparison of the calculation results with experimental data for test structures formed in a two-layer silicon dioxide-crystalline silicon substrate showed that the developed simulation method makes it possible to predict the shape of structures fabricated by a focused ion beam with good accuracy. Keywords: Focused ion beam, sputtering, level set method.

Физико-химические свойства и функциональные характеристики безвольфрамового твердого сплава системы “TiC – TiNi”, подвергнутого ионно–лучевой обработке

In the work presents the results of a study of the influence of the effect of a continuous ion beam of the composition (Ar++Zr+) with an ion energy E ≈ 20 keV and an irradiation dose D ≈ 5·1017 ion/cm2 on the phase composition, chemical state, microhardness, wear resistance during friction against an abrasive and corrosion resistance of tungsten-free hard alloys of the TiC – TiNi system. Analysis of the structure, morphology, and chemical state of the samples before and after ion treatment was carried out using scanning electron and scanning probe microscopy, as well as X-ray photoelectron spectroscopy and X-ray diffraction analysis. The features of the change in the physicochemical state of the tungsten-free hard alloy of the “TiC – TiNi” system subjected to continuous ion beam irradiation are revealed. It has been experimentally established that ion-beam treatment provides an increase in microhardness, wear resistance and corrosion resistance of the hard alloy.

Ion beam irradiation: Novel approach for preparation of Ag coated N doped nanocrystalline anatase TiO2 films

Herein, a novel approach of ion beam irradiation (nitrogen beam dose ∼ 1013 ions/cm2, 40 keV for 30 min in ultra-high vacuum conditions) is explored for the preparation of nanocrystalline anatase TiO2 modified with nitrogen (N) and silver (Ag). The prepared materials characterized using XRD, Raman, UV–Visible spectroscopy, EIS and wettability techniques. The structural-optical studies revealed the interstitial and/or substitutional doping of N in O-Ti-O matrix supported by Williamson-Hall lattice strain values and dispersion of Ago particles at the TiO2 surface. Raman spectra confirmed the crystallization of anatase TiO2 wherein red shifting-broadening of Raman active modes are due to the phonon confinement and structural defects due to favored substitutional N3– doping in TiO2 lattice. The higher values of Z′, Z″, and RCT in Nyquist plots and the blue shift of ωmax in Bode plots for irradiated films further supported the substitutional doping of N rather than the interstitial one.

Skyrmions Under Control-FIB Irradiation as a Versatile Tool for Skyrmion Circuits.

Magnetic data storage and processing offer certain advances over conventional technologies, amongst which nonvolatility and low power operation are the most outstanding ones. Skyrmions are a promising candidate as a magnetic data carrier. However, the sputtering of skyrmion films and the control of the skyrmion nucleation, motion, and annihilation remains challenging. This work demonstratesthat using optimized focused ion beam irradiation and annealing protocols enables the skyrmion phase in W/CoFeB/MgO thin films to be accessed easily. By analyzing ion-beam-engineered skyrmion hosting wires, excited by sub-100 ns current pulses, possibilities to control skyrmion nucleation, guide their motion, and control their annihilation unfold. Overall, the key elements needed to develop extensive skyrmion networks are presented.