Ion Beam Technology Research Articles

Creation and Development of the Ion Beam Technology

A historical overview of the development of domestic ion beam technology is presented. It is shown that the wide application of the ion beam technology is facilitated by (i) the creation of a method for compensating the positive space charge inside an ion-source accelerating gap by the negative space charge of electrons held in crossed electric and magnetic fields, which makes it possible to increase the density of the extracted ion current by orders of magnitude over the Child–Langmuir limitations; (ii) the development of the original cold cathode sources forming ion beams from almost any compounds; and (iii) the creation of the reactive ion beam etching technique characterized by precise etching with inert gas ion beams and the selectivity of liquid etching. Based on these advances, a series of ion source modifications and technological equipment are developed for use in the manufacture of micro- and nanoelectronic products, optics, piezoelectric quartz technology, medicine, and other fields. The ways of improving the ion beam technology by creating high-energy neutral particle sources and technologies based on their use are shown.

Generation of Boron Ions for Beam and Plasma Technologies

The urgency of the study of generation of beams and plasmas containing boron ions is caused by their application in ion-beam and plasma technologies of modification of the surface properties of not only semiconductors, but also structural materials. This is due to the fact that boron compounds are hard and chemically resistant materials that can be used to create hardening and protective surface coatings for a wide nomenclature of details. The operating principle and the characteristics of the experimental setup developed for generation of plasma and boron ion beams intended for creation of such coatings are presented, including an ion source based on vacuum arc with separation of boron isotopes in a magnetic field intended for highdose ion implantation, a plasma generator with boron target intended for obtaining coatings by magnetron sputtering, and a forevacuum electron source intended for synthesis of surface boron-containing coatings by electron beam evaporation.

Sensitivity Improvement to Active Piezoresistive AFM Probes Using Focused Ion Beam Processing.

This paper presents a comprehensive modeling and experimental verification of active piezoresistive atomic force microscopy (AFM) cantilevers, which are the technology enabling high-resolution and high-speed surface measurements. The mechanical structure of the cantilevers integrating Wheatstone piezoresistive was modified with the use of focused ion beam (FIB) technology in order to increase the deflection sensitivity with minimal influence on structure stiffness and its resonance frequency. The FIB procedure was conducted based on the finite element modeling (FEM) methods. In order to monitor the increase in deflection sensitivity, the active piezoresistive cantilever was deflected using an actuator integrated within, which ensures reliable and precise assessment of the sensor properties. The proposed procedure led to a 2.5 increase in the deflection sensitivity, which was compared with the results of the calibration routine and analytical calculations.

Drag on a spacecraft produced by the interaction of its magnetic field with the Earth's ionosphere. Physical modelling

The dynamic interaction of a “magnetized” sphere (a sphere with a magnetic field source) with a hypersonic rarefied plasma flow was studied experimentally to model the interaction of a “magnetized” spacecraft with the ionospheric plasma. The experiments were conducted at the plasma flow velocity parallel and normal to the sphere's magnetic field. The electromagnetic drag coefficient was determined as a function of the ratio of the magnetic pressure to the dynamic pressure and the ratio of the mini-magnetosphere dimension to the spacecraft dimension (sphere radius). It was shown that a spacecraft's magnetic field of about 0.8–1.5 T produces an electromagnetic drag comparable with the drag produced using ion beam technologies of space debris removal, which require dedicated spacecraft with plasma accelerators. Energy-efficient compact sources of a 0.8–1.5 Т magnetic field for space debris objects may be made using special arrangements of small-size permanent magnets – Halbach arrays.

On the formation of nanostructures by inducing confined plasma expansion

For the past few years, there has been a rapid rise in the use of ion beam technology for surface nanostructuring of various materials. For LiNbO3 single crystals, we have observed surface nanostructures after surpassing a potential energy ≈35 keV of the incident ion. Here, we introduce plasma expansion approach, based on a dimensionless self-similar parameter, to explain the main features of the mechanism responsible for the created structures. The analysis of the results reveals that the temperature ratio between ions-to-electrons does not change the profile of the expansion at early time. However, increasing the temperature ratio makes the expansion domain longer; nevertheless, a further rising leads to decrease the expansion range. Furthermore, the niobium ions exhibit a dominant effect, in comparison to lithium ions, for the modification of the plasma-expanded region.

Surface functionalization of epitaxial graphene using ion implantation for sensing and optical applications

Surface functionalization has been shown to allow tailoring of graphene lattice thus making it suitable for different applications like sensing, supercapacitance devices, drug delivery system and memory devices. In this work, surface functionalization of epitaxial graphene on SiC (EG/SiC) was done by ion beam technology (30 keV Ag− ions at fluences ranging from 5 × 1012 ions/cm2 to 5 × 1014 ions/cm2), which is one of the most precise techniques for introducing modifications in materials. Atomic force microscopy showed presence of nanostructures in ion implanted samples and Photoluminescence and X-ray photoelectron spectroscopy revealed that these are probably silicon oxy carbide. High-resolution transmission electron microscopy (HRTEM) showed decoupling of buffer layer from SiC substrate at many places in ion implanted samples. Further, HRTEM and Raman spectroscopy showed amorphization of both graphene and SiC at highest fluence. Fluence dependent increase in absorbance and resistance was observed. Gas sensors fabricated on pristine and ion implanted samples were able to respond to low concentration (50 ppb) of NO2 and NH3 gases. Detecting NH3 gas at low concentration further provides a simple platform for fabricating highly sensitive urea biosensor. We observed response inversion with increasing fluence along with presence of an optimal fluence, which maximized gas sensitivity of EG/SiC.

Comparison of Multiple Methods for Obtaining P$\Omega$ Resistances With Low Uncertainties

Capabilities for high resistance determinations are essential for calibration of currents below 1 pA, as typically requested in several applications, including semiconductor device characterization, single electron transport, and ion beam technologies. This need to calibrate low currents warrants the expansion of accessible values of high resistance. We present several methods for measuring resistances on the PΩ scale, namely potentiometry, dual source bridge measurements, and teraohmmeter usage, all of which are subsequently compared to theoretical calculations. These methods were used to measure four 1 PΩ resistances, one 10 PΩ resistance, and one 100 PΩ resistance, all generated by wye-delta networks containing three resistance elements. The differences between the experimentally obtained values and the theoretical values typically agree within 1 % for 1 PΩ, 10 PΩ and 100 PΩ resistances and the measurement uncertainties for the three techniques were estimated to be between 0.4 % to 4.8 % for 1 PΩ, 2.8 % to 5.6 % for 10 PΩ, and 4.4 % to 10.2 % for 100 PΩ.

Operando Laboratory X-Ray Imaging of Silver-Based Gas Diffusion Electrodes during Oxygen Reduction Reaction in Highly Alkaline Media.

Operando laboratory X-ray radiographies were carried out for imaging of two different silver-based gas diffusion electrodes containing an electroconductive Ni mesh structure, one gas diffusion electrode composed of 95 wt.% Ag and 5 wt.% polytetrafluoroethylene and one composed of 97 wt.% Ag and 3 wt.% polytetrafluoroethylene, under different operating parameters. Thereby, correlations of their electrochemical behavior and the transport of the 30 wt.% NaOH electrolyte through the gas diffusion electrodes were revealed. The work was divided into two parts. In the first step, the microstructure of the gas diffusion electrodes was analyzed ex situ by a combination of focused ion beam technology and synchrotron as well as laboratory X-ray tomography and radiography. In the second step, operando laboratory X-ray radiographies were performed during chronoamperometric measurements at different potentials. The combination of the ex situ microstructural analyses and the operando measurements reveals the impact of the microstructure on the electrolyte transport through the gas diffusion electrodes. Hence, an impact of the Ni mesh structure within the gas diffusion electrode on the droplet formation could be shown. Moreover, it could be observed that increasing overpotentials cause increasing electrolyte transport velocities and faster droplet formation due to electrowetting. In general, higher electrolyte transport velocities were found for the gas diffusion electrode with 97 wt.% Ag in contrast to that with 95 wt.% Ag.

A nanoscale study of the formation of Fe-(hydr)oxides in a volcanic regolith: Implications for the understanding of soil forming processes on Earth and Mars

Abstract Iron(hydr)oxides are one of the most important constituents of regoliths and soils derived from volcanic rocks both on Earth and Mars, often giving them their characteristic red color. This study deciphers for the first time an underlying mechanism for the formation of Fe-(hydr)oxides in a regolith which can occur during the weathering of basaltic glass; Fe-(hydr)oxides are prominent alteration products of volcanic regolths. An excellent example of these conditions is the early stage of basaltic glass weathering in the Martian regolith simulant JSC MARS-1A. In this study, a combination of focused ion beam technology and analytic transmission electron microscopy is employed in order to characterize basaltic glass weathering down to the nanometer level. Our results show that the formation of Fe-(hydr)oxide phases such as ferrihydrite, magnetite/maghemite and hematite during alteration of basaltic glass is based on complex and formerly unknown sequences of dissolution-precipitation reactions and pressure induced coalescence, segregation, aggregation, densification and growth processes. The weathering of the glass starts with its dissolution and subsequent precipitation of hydrous amorphous silica-bearing pockets rimmed by nano-size domains of ferrihydrite. An increase in molar volume during this process leads to an overall volume expansion, which promotes (a) growth of the hydrous silica through coalescence of individual pockets, (b) agglomeration of ferrihydrite domains to larger and denser aggregates in between layers or along the surfaces of plagioclase, hydrous amorphous silica and amorphous Al-(hydr)oxides, (c) formation of hematite within dense aggregates of ferrihydrite or as larger nanoparticles within an hydrous amorphous Si-Al-rich phase and (d) the break-up of plagioclase crystals and the replacement of these fragments by an hydrous amorphous Fe-Al-Si-bearing phase. At a later weathering stage, ferrihydrite nano-domains can also transform into magnetite/maghemite nanoparticles, which occur as layers around and on the surface of larger plagioclase crystals. This study also indicates the presence of past nano-environments in close proximity to each other, as for example layers of imogolite and ferrihydrite/hydrous amorphous silica occur only nanometers apart from each other on the opposite sides of unaltered glass. In accord with previous mineralogical studies of JSC MARS-1, the observed bulk and nano-mineralogical composition indicate that early alteration processes of basaltic glass under dry and cold conditions are mainly controlled by the formation of Fe-(hydr)oxides and minor imogolite and kaolinite. Recent mineralogical studies indicate that alteration processes at these conditions may have been the dominant weathering processes over long time periods on the Martian surface.

Computer-aided manufacturing and focused ion beam technology enable machining of complex micro- and nano-structures

We present a novel framework for the fabrication of geometrically complex structures at the micro- and nano-scale which relies on the synergy of integrated computer-aided design and manufacturing systems (CAD/CAM) and focused ion beam (FIB) technology in a scanning electron microscope. Here we utilise industry standard G-code syntax, for the first time, to FIB machining by designing geometries with CAD, defining machining strategies and exporting G-codes with CAM and generating a coordinate list-based beam path by using a custom-built interpreter program. This allows the fabrication of complex structures from CAD models using syntax which is readily understood in the general fabrication industry. The use of G-code allows optimization of the beam path towards a reduction of beam blanking operations and tracing of contours, leading to minimized re-deposition of material. We give a detailed description of the method, use an application example to demonstrate advantages and prospects of the approach and provide the free and open-source interpreter program CAM2FIB for application of this method. We contrast and compare various existing available milling strategies and demonstrate the versatility of G-code based programming.

Spatially Engraving Morphological Structure on a Polymeric Surface by Ion Beam Milling.

Polymer surface patterning and modification at the micro/nano scale has been discovered with great impact in applications such as microfluidics and biomedical technologies. We propose a highly efficient fabricating strategy, to achieve a functional polymer surface, which has control over the surface roughness. The key development in this fabrication method is the polymer positive diffusion effect (PDE) for an ion-bombarded polymeric hybrid surface through focused ion beam (FIB) technology. The PDE is theoretically explored by introducing a positive diffusion term into the classic theory. The conductivity-induced PDE constant is discussed as functions of substrates conductivity, ion energy and flux. The theoretical results agree well with the experiential results on the conductivity-induced PDE, and thus yield good control over roughness and patterning milling depth on the fabricated surface. Moreover, we demonstrate a controllable surface wettability in hydrophobic and superhydrophobic surfaces (contact angles (CA) range from 108.3° to 150.8°) with different CA hysteresis values ranging from 31.4° to 8.3°.

Studies on Application of Ion Beam Breeding to Industrial Microorganisms at TIARA

Mutation-breeding technologies are useful tools for the development of new biological resources in plants and microorganisms. In Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) at the National Institutes for Quantum and Radiological Science and Technology, Japan, ion beams were explored as novel mutagens. The mutagenic effects of various ion beams on eukaryotic and prokaryotic microorganisms were described and their application in breeding technology for industrial microorganisms were discussed. Generally, the relative biological effectiveness (RBE) depended on the liner energy transfer (LET) and the highest RBE values were obtained with 12C5+ ion beams. The highest mutation frequencies were obtained at radiation doses that gave 1%–10% of surviving fraction. By using 12C5+ ion beams in this dose range, many microorganisms have been improved successfully at TIARA. Therefore, ion-beam breeding technology for microorganisms will have applications in many industries, including stable food production, sustainable agriculture, environmental conservation, and development of energy resources in the near future. Moreover, genome analyses of the ion-beam-induced mutants are in progress to clear the differences of mutational functions induced by different LET radiations in microorganisms. Further characterizations of mutations induced by different LET radiations will facilitate more effective use of ion beams in microorganisms breeding.

Adhesion Enhancement of Polymer Surfaces by Ion Beam Treatment: A Critical Review

Polymers are widely used in different types of industries ranging from microelectronics, medical to space applications. However, polymer materials are seldom used in their pristine state and are in need of selective surface treatment to induce a specific response which is a challenging and complex task. Adhesion enhancement of polymers is one of the major requirements that can be achieved with ion beam technology at low cost. Surface enhancement involves keeping the bulk properties of materials unchanged and modifying only the surface properties to achieve optimum results.<br/> In this review, we illustrate the use of ion beam technology to modify the surface properties of polymers for potential biomedical and microelectronics applications. This review focuses on effects on the adhesion characteristics for different polymer materials of various optimizable parameters such as type of ion used, ion energy regime (low to medium to high) and the ion fluence range.

Finishing of metal optics by ion beam technologies

Ultraprecise mirror devices show considerable potential with view to applications in the visible and the ultraviolet spectral ranges. Aluminum alloys gather good mechanical and excellent optical properties and thus they emerge as important mirror construction materials. However, ultraprecision machining and polishing of optical aluminum surfaces are challenging, which originates from the high chemical reactivity and the heterogeneous matrix structure. Recently, several ion beam-based techniques have been developed to qualify aluminum mirrors for short-wavelength applications. We give an overview of the state-of-the-art ion beam-processing techniques for figure error correction and planarization, either by direct aluminum machining or with the aid of polymer or inorganic, amorphous surface films.

Enhanced soft magnetic properties of iron powders through coating MnZn ferrite by one-step sol–gel synthesis**Project supported by the Natural Science Foundation of Shandong Province, China (Grant No. ZR2018MEM020).

The MnZn ferrite coating formed on the surface of iron-based soft magnetic powders via facile and modified sol–gel process has been fabricated to obtain better magnetic performance due to its higher permeability compared with traditional nonmagnetic insulation coatings. The influence of the MnZn ferrite contents on the magnetic performance of the soft magnetic composites (SMCs) has been studied. As the MnZn insulation content increases, the core loss first experiences a decreasing trend that is followed by progressive increase, while the permeability follows an increasing trend and subsequently degrades. The optimized magnetic performance is achieved with 2.0 wt% MnZn ferrite, which results from the decrement of inter-particle eddy current losses based on loss separation. A uniform and compact coating layer composed of MnZn ferrite and oxides with an average thickness of is obtained by utilizing ion beam technology, and the interface between the powders and the coating shows satisfied adhesiveness compared with the sample directly prepared by mechanical mixing. The evolution of the coating layers during the calcination process has been presented based on careful analysis of the composition and microstructure.

Investigation on enhancing the thermal conductance of gallium-based thermal interface materials using chromium-coated diamond particles

The focus of this paper is how to efficiently enhance the thermal conductance of gallium-based thermal interface materials (TIMs) and greatly avoid the excessive consumption of liquid metal during its application. Highly heat-conducting diamond particles are selected as the reinforced additives for pure gallium on account of their mature technology of surface metallization. To improve the interface combination status between those inorganic fillers and liquid metal matrix, chromium transition layer is deposited on the surfaces of diamond particles by magnetron sputtering method. The phase composition of cladding layer on diamond particles is analyzed by transmission electron microscopy combined with focused ion beam technology. To measure the thermal conductivity of gallium-based TIM filled with chromium-coated diamond particles, a specific three-layer structure sample is made for laser flash analysis and the corresponding theoretical fitting model is deduced subsequently. After performing iterative solution through programming, our results present that 47 wt% addition of chromium-coated diamond particles can dramatically increase the thermal conductivity of pure gallium from 29.3 to 112.5 W/(m·K) at room temperature. And fortunately, it has not yet been observed that the chromium coating is over consumed by liquid metal or the thermal conductivity of composite seriously degrades after thermal aging treatment at 80 °C for 192 h, strongly indicating that chromium could be used as the diffusion barrier layer for heat-conducting particles and the metal substrates to maintain long-term reliable service of gallium-based TIMs.

Improved manufacture of hybrid membranes with bionanopore adapters capable of self-luting

The authors’ recent concept of bioinorganic filtration devices made up of solid-state membranes (SSMs) accommodating ring-shaped, ribonucleic acid (RNA)-stabilized tobacco mosaic virus (TMV) coat protein (CP) assemblies with central 4 nm holes as genetically encoded ‘pore-in-pore’ fittings, to convey size and charge specificity to the membranes’ permeability, has been elaborated. Key developments for simplifying and finishing the unique combination apply to both soft- and hard-matter components: previous SSMs with millions of conical pores demanded sophisticated lithography to achieve a taper trapping the bionanopores upon insertion in a flow. Now focused helium (He) ion beam technology has enabled efficient, fast preparation of silicon nitride templates adapted to the nanorings. Proof-of-concept experiments reveal that negative charges imparted by nucleic acids exposed on the bionanopores might improve electrophoretic implantation further. Suitable peptides installed on the outer nanoring rim had been shown to nucleate spatially confined silica deposition from liquid precursors, which have been optimized in order to seal the annular gaps between bio and inorganic SSM pores by ‘bionic glue’. Finally, two engineered CP variants and a modified scaffold RNA were established for novel TMV nanoring types with altered pore charges, which also allow installing accessory molecules for advanced filtration and conversion tasks.

Multilayer X-Ray Image-Forming Optics

An overview is presented of the current state of research underway at the Institute for the Physics of Microstructures in the field of multilayered X-ray imaging optics. New ways of studying the surfaces of mirror substrates and aberrations of optical systems are described, along with the ion-beam technology of super-polishing, aspherization, and correcting local errors in shape. The development of new diagnostic methods is described, as are the obtained record reflection coefficients of multilayer interference mirrors based on beryllium.

In situ experimental study on material removal behaviour of single-crystal silicon in nanocutting

Ductile-mode removal of single-crystal silicon can be achieved by strictly controlling the cutting parameters, which significantly affects the machining efficiency. To improve the surface quality without reducing the machining efficiency, nanocutting experiments were performed to study the material removal behaviour using a specially designed nanocutting platform with a scanning electron microscope (SEM). Diamond tools with different edge radii were fabricated by focused ion beam (FIB) technology. The initiation and propagation of microcracks were observed online by an SEM to analyse the material removal behaviour of single-crystal silicon in the brittle mode. The effects of the crystal orientation and tool edge radius on the critical thickness of the brittle-ductile transition were investigated. Additionally, in the ductile mode, the influence of the tool edge radius on the minimum cutting thickness (MCT) was analysed. It was determined that the ratio of the MCT to the tool edge radius was 0.32–0.50, regardless of the tool edge radius. This in situ experimental study can provide a direct verification for the material removal behaviour in nanocutting.

Roadmap for the application of ion beam technologies to the challenges of nuclear energy technologies

The use of ion beams to estimate materials performance for nuclear energy applications is advancing at a rapid rate with ion irradiations having been shown to produce radiation effects data of direct relevance for understanding neutron-induced displacement damage. Ion beam irradiation shows considerable promise for assisting in down selecting candidate materials for use in nuclear energy systems. Furthermore, ion beams allow rapid achievement of materials damage levels not accessible by neutron irradiation in test reactors due to cost and time constraints. Compared to test reactor irradiations, the relatively open configuration of ion beam irradiations allows capture of data on the effects of irradiation under very specific conditions of temperature, radiation dose, and radiation dose rate that are difficult or impossible to achieve otherwise.There are still multiple challenges to the deployment of ion beam data in support of reactor materials qualification arising from the lack of a detailed mechanistic understanding of potential difference between ion-induced and neutron induced materials damage. Recently, the Nuclear Science User Facilities presented a roadmap for the development and enhancement of current U.S. ion beam irradiation technologies within university and national laboratory settings, and especially for the deployment of new highly controlled in situ interrogation of materials during irradiation to provide dynamic and mechanistic data for model development. In this presentation, the status and capabilities of relevant U.S. ion beam facilities will be summarized and recommended “best practices” for performing ion irradiations will be described. The potential role of ion beam irradiations to assist the development and deployment of reactor materials will be outlined. Key objectives include developing methods for rapid and cost-effective materials selection and development, characterizing fundamental material response under irradiation, and developing a robust mechanistic understanding of microstructure evolution under irradiation (including development and validation of reliable predictive models for microstructure evolution).