Argon Beam Research Articles

Improvement of extracted ion beam from cold cathode Penning ion source

A direct current cold cathode Penning ion source is operated at the optimum parameters and pressure equal to 7×10−4 mmHg using argon gas. It consists of a copper cylindrical hollow anode and two movable molybdenum discs cathodes are placed symmetrically at two ends of the anode. Argon ion beam is extracted from the ion source by using extractor of different aperture diameter equal to 2.5, 3, 3.5, 4 and 4.5mm respectively. The extractor is placed at different distances from the ion exit aperture equal to 5, 10, 15 and 20mm respectively. It is found that at extractor aperture diameter equal to 3.5mm, ion exit aperture - extractor distance equal to 10mm and extraction potential applied on the extractor is equal to −500V, the optimum extracted ion beam current equal to 543 μA can be obtained. A comparison for Penning ion source without and with the extractor is made at the same optimum operating parameters, it is found that the extracted ion beam current from Penning ion source with the extractor increases about twice its initial value of Penning ion source without the extractor.

Gold microelectrodes fabricated by a print-and-imprint method using laser-drilled polyimide through-hole masks

Multiple sets of gold (Au) four-terminal microelectrodes comprising 100 μm-scale pad electrodes and 20 μm-wide lead lines were fabricated on a silicon substrate by a print-and-imprint method involving laser drilling and screen printing. Laser drilling of 12.5 μm-thick polyimide (PI) sheets with a picosecond-pulse laser enabled the fabrication of PI membranes with designed patterns of through holes. The through holes had a frustum shape, and the average hole diameters on both the laser entry and exit sides of the PI films enlarged with an increase in the applied repetition rate. The hole patterns designed with submicrometer position accuracy were prepared using a linear motor stage. Liquid ultraviolet (UV)-curable resin, exhibiting a high viscosity (11.0 Pa s) and a high dry-etching resistance to argon (Ar) ion beam milling after UV curing, was placed onto a substrate surface as droplets by screen printing, corresponding to the hole patterns of the PI through-hole masks. The average volume of the liquid droplets could be tuned in the range of 0.02–0.54 pl, which depended on the volumes of the laser-drilled frustum holes. The volumes of liquid resin necessary to fill the mold recesses were adjusted site-selectively by the number of resin droplets printed on a metal-deposited substrate surface. Fluorescence microscopy with a fluorescent dye-doped resin indicated that the imprinted resist patterns had a residual layer thickness in the range of 15–28 nm. The Au electrodes with a 30 nm-thickness could be fabricated by subsequent Ar ion beam milling and removal of a sacrificial metal layer.

Contact Joining Study of Copper and Nickel Nanowires

Metal nanowires (MNWs) are proven to be excellent innovative conducting materials for next generation of nanodevices either in form of transparent electrodes for solar cells or for interconnecting conducting nanowires to incorporate multiple nanodevices. To exploit exceptional properties of MNWs networks in future nanodevices, effective joining between various types of MNWs is critical. This study is based on joining of copper nanowires (Cu-NWs) and nickel nanowires (Ni-NWs) through argon (Ar+) ions beam irradiation. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and transmission electron microscopy (TEM) results exposed that Ag-NWs are effectively connected to each other on intersecting positions and crystal structure also remained un-damaged. In addition, the results exhibit that Ar+ ions beam irradiation induced sputtering of atoms from NWs lattices lead to produce point defects and accumulation of these point defects on crossing sharp angle contact areas, eventually lead to connect these NWs. A basic perception is the exploitation of Ar+ ions beam irradiation induced nanowelding technique for construction of complex and random networks of well-connected multiple MNWs for application in future nanodevices or optoelectronic devices.

(Invited) Welding of Nickel Nanowires By Ions Beam Irradiation: From Small to Large Scale

In order to replace conventional transparent conducting electrodes, metal nanowires (MNWs) networks have long been act as promising contenders due to their high mechanical flexibility. However, nanowire-nanowire contact resistance is main technical obstruction in terms of improvement in their performance. To reduce nanowire-nanowire contact resistance, welding of nanowires (NWs) is essential. In this work, MeV proton and argon ions beam irradiation induced nanoscale welding technique to fabricate X-, Y-, II- and T-shaped molecular junctions between nickel nanowires (Ni-NWs) is presented. Ni-NWs are irradiated by 2.75 MeV proton ions and 3.5 MeV argon ions at doses 1x1016ions/cm2 and 5x1015 respectively while temperature is kept constant. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and x-ray diffraction (XRD) results reveal that Ni-NWs are welded without losing stability in crystal structures of NWs. Afterward, a two-dimensional large scale random network of Ni-NWs is fabricated by 3 MeV proton ions beam irradiation induced nanoscale welding of Ni-NWs at crossing positions. Proton ion beam induced large scale network fabrication is confirmed by TEM and SEM techniques. Moreover, these networks are characterized optically using UV-VIS spectroscopy. It is observed that at a beam fluence of 5x1015 ions/cm2, perfect molecular junctions between Ni-NWs in X-, II-, and V-shapes are achieved and a large scale welded network of Ni-NWs is obtained without distorting the morphology of NWs. Moreover, structure of Ni-NWs remains stable under 3MeV proton ions beam irradiation and networks are found to be optically transparent. The results exhibit that fabrication of Ni-NWs network precede through three steps: i- High energy ions beam irradiation induced heat spikes lead to locally heat and fuse Ni-NWs, ii- Formation of molecular junctions on small scale, iii- Formation of large scale network Ions beam irradiation induced welding of Ni-NWs can improve performance of NWs networks by reducing contact resistance between NWs for application as transparent conducting electrodes. These high quality welded MNWs networks may potentially be applied as transparent conducting electrodes in optoelectronic devices.

An argon ion beam milling process for native AlOx layers enabling coherent superconducting contacts

We present an argon ion beam milling process to remove the native oxide layer forming on aluminum thin films due to their exposure to atmosphere in between lithographic steps. Our cleaning process is readily integrable with conventional fabrication of Josephson junction quantum circuits. From measurements of the internal quality factors of superconducting microwave resonators with and without contacts, we place an upper bound on the residual resistance of an ion beam milled contact of 50 mΩ μm2 at a frequency of 4.5 GHz. Resonators for which only 6% of the total foot-print was exposed to the ion beam milling, in areas of low electric and high magnetic fields, showed quality factors above 106 in the single photon regime, and no degradation compared to single layer samples. We believe these results will enable the development of increasingly complex superconducting circuits for quantum information processing.

Low-Energy Ion-Species-Dependent Induction of DNA Double-Strand Breaks: Ion Energy and Fluence Thresholds.

The goal of this study was to determine the critical ion-radiation conditions under which heavy ion beams can induce DNA double-strand breaks. Helium, nitrogen and argon-ion beams in the energy range of 20 eV to 2 keV were used to irradiate naked DNA plasmid pGFP to fluences of 1, 2 and 4 × 1015 ions/cm2. The topological forms of DNA were subsequently analyzed using gel electrophoresis. The DNA forms were changed from the original supercoiled to damaged relaxed and linear forms, depending on the ion mass, energy, fluence and inertia. We found ion energy and fluence thresholds above which direct double-strand breaks can occur. The threshold is discussed in terms of the areal ion-energy density and the cross-section.

Shaped graft for aneurysmal bone cyst of upper limb bones

The optimal treatment of aneurysmal bone cyst remains challenging. The aim of this prospective study was to evaluate the results of using bone grafts shaped to the defects caused by aneurysmal bone cysts of upper limb bones. Fifteen patients (12 males and 3 females) with an average age of 12 years (range 6–16 years) were treated for aneurysmal bone cysts of upper limb bones by intralesional resection, argon beam coagulation and shaped bone graft. The grafts were harvested from 14 patients (11 fibulas and 3 iliac bones) and from the mother of one patient (proximal fibula). Osteosynthesis was required to stabilize the graft in four cases. The modified Enneking’s scoring system was used for functional evaluation. One patient developed partial recurrence at 6 months and required reoperation. Superficial wound infection was encountered in one patient. Shortening of the humeral segment was seen in two patients (1 and 1.5 cm) but without angular deformity. After a mean follow-up of 45 months (range 24–68 months), the mean functional score was 97.3%. This technique proved to be reliable in obtaining a well reconstructed and growing bone with no or minimal deformity and good function.

A Small Spot, Inert Gas, Ion Milling Process as a Complementary Technique to Focused Ion Beam Specimen Preparation.

This paper reports on the substantial improvement of specimen quality by use of a low voltage (0.05 to ~1 keV), small diameter (~1 μm), argon ion beam following initial preparation using conventional broad-beam ion milling or focused ion beam. The specimens show significant reductions in the amorphous layer thickness and implanted artifacts. The targeted ion milling controls the specimen thickness according to the needs of advanced aberration-corrected and/or analytical transmission electron microscopy applications.

Formation of modified layers on the outer surface of cylindrical samples from E110 alloy under the influence of radial argon ions beam in the mode of multilayered films ion mixing

Results of experiments of modified layers formation on the long-length cladding tubes from E1 10 alloy (Zr – 1 % Nb) are presented in this paper. Samples were modified by surface polishing by radial Ar+ beam with wide-range energy spectrum, series of films from alloying elements deposition and their subsequent processing in the ion mixing mode. The concentration of implanted atoms is 1–5 at. %, with a maximum penetration depth of 1–2 μm

Study the optimum dimensions and operating parameters of Penning ion source

In this work, design and construction of a DC cold cathode Penning ion source is described. It consists of cylindrical hollow anode and two movable disc cathodes that are placed symmetrically at two ends of the anode. The electrical discharge and the output ion beam characteristics of the ion source are measured using argon gas. It is found that the optimum dimensions of anode–cathode distance, ion exit aperture diameter, and ion exit aperture – Faraday cup distance are equal to 8, 1.5, and 30 mm, respectively. The ion source efficiency was calculated at discharge current equal to 1.2 mA, different anode–cathode distances and pressures using argon gas. It is found that at anode–cathode distance equal to 8 mm and pressure equal to 7 × 10−4 mmHg, a maximum ion source efficiency equal to 27.1% can be obtained. The surface hardness of molybdenum specimen is measured after exposure to argon ion beam for two hours at pressure equal to 7 × 10−4 mmHg, discharge voltage equal to 3.5 kV, discharge current equal to 0.6 mA, and output ion beam current equal to 165 μA using argon gas. It is found that the surface hardness of molybdenum specimen is decreased by a factor of 24.2%.

Silica imprint templates with concave patterns from single-digit nanometers fabricated by electron beam lithography involving argon ion beam milling

To maintain the silica surface of imprint templates without a fluorine-containing passivation layer on sidewalls after dry etching, we investigated whether a physical dry etching process entailing exposure to Ar ion beam is useful for the fabrication of silica templates. An almost same etching rate of a positive-tone electron beam (EB) resist as silica in Ar ion beam milling allowed for the fabrication of bar-shaped patterns with micrometer lengths and widths for moiré alignment and of hole patterns with diameters of around 20 nm in silica templates. The EB resist layer of 40 nm thickness generated partially non-etched defects of 10-nm-diameter holes in silica templates because the Ar ion beam was completely unable to reach silica surfaces through resist sidewalls with a depth of 40 nm. The break-through etching of a hard mask sacrifice Cr layer with a thickness of 5 nm by Ar ion milling and the subsequent inductively coupled plasma etching of silica enabled the fabrication of silica hole templates with diameters of 7–20 nm and depths of 20–30 nm.

Modification of optical and electrical properties of SnO2 under the influence of argon ion beam

Thin films of tin oxide were deposited on the glass substrates at a room temperature using reactive magnetron sputtering. The ratio between O2/Ar and the discharge voltage is maintained in such a mode when the deposited films are dielectrics. After the deposition, the films were irradiated with an argon ions beam. The modification of the optical and electrical properties of the films depending on the irradiation time was studied. Optical properties of the films were analyzed in the range of 300-1100 nm using photometry and structural X-ray diffraction. The diffractometric research showed that the films, deposited on a substrate, had a crystal structure, and after argon ions irradiation they became quasi-crystalline (amorphous). It was found that the modification in the transmittance was correlated with modifications in the meaning of surface resistance. The dielectrics films SnO2 with increasing exposure time became conductive and then the electrical resistance decreased and reached a minimum at 13.2 seconds. Then resistance films began to increase.

Legitimacies of the growth of oxide films on ion-modified samples from the alloy E110 at high-temperature oxidation

The possibility to obtain barrier layers during the surface modification by ion-plasma to decrease the oxidation and hydrogenation rate of fuel claddings from zirconium alloys at various operation conditions is studied in this paper. Fuel claddings from the alloy E110 obtained on the outer surface of fuel elements after ion polishing are determined on the basis of calculations and experiments performed: the average ion energy in a beam is 3-4 keV, the ion current is 0.4-0.7 mA cm-2, and the total irradiation dose is 5×1018 ion cm-2. Cleaning and polishing of samples from the alloy E110 were carried out on the installation ILUR-03 by a radial beam of argon ions with a wide energy spectrum. Thin films (up to 100 nm) of alloying elements – Fe, Al, Mo, Y, Mg, and Cr were obtained on the polished surface by magnetron deposition and then implanted into the near-surface layer under the influence of a radial beam of argon ions. Study of the element composition of cleaned and modified near-surface layers was performed by X-ray microanalysis. A part of the samples was preliminarily autoclaved in distilled water at the temperature of 350 °C and the pressure of 17 MPa for 500 h to obtain a protective layer from an oxide film enriched by implanted elements. It is shown that alloying elements are mostly located at the oxide-metal boundary and in the oxide.

OPTICAL AND ELECTRICAL PROPERTIES OF ARGON ION BEAM IRRADIATED PVA/Ag NANOCOMPOSITES

In this work, PVA/Ag nanocomposites films were prepared using solution casting technique, these films were irradiated with Argon ion beam to modify the structure. The main objective of the study is to enhance the optical and electrical properties of the polymer nanocomposites films by irradiation. The conventional characterization techniques such as UV–Visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscope (TEM) and dielectric measurement are employed to understand the structure–property relations. FTIR analysis of these composite films shows chemical changes and a significant impact on them can be observed after irradiation. After doping, the XRD data shows silver nanoparticles formation in the PVA polymer. The band gap energy of samples is decreased with increases in the concentration of silver nanoparticles and ion beam fluence, which gives clear indication that ion beam irradiation induced defects are formed in the composite systems. The electrical conductivity, dielectric loss [Formula: see text] and dielectric constant [Formula: see text] are increased with increasing ion beam fluence and Ag dopant concentration.

IRRADIATION AND SILVER DEPOSITION FOR IMPROVEMENT OF NASOPHARYNGEAL AIRWAY MEDICAL DEVICE PROPERTIES

The thermal and mechanical properties of nasopharyngeal airway (NPA) samples are improved by irradiation using 4[Formula: see text]keV oxygen and nitrogen ion beams with different ion fluences varying from [Formula: see text] ions/cm2to [Formula: see text] ions/cm2. The thermal stability of NPA medical device increases with increasing nitrogen and oxygen ion fluences. The tensile strength increased from 48[Formula: see text]MPa for unirradiated sample to 74[Formula: see text]MPa for samples irradiated with nitrogen and to 58[Formula: see text]MPa for samples irradiated with oxygen ion, while the elongation at break decreases for irradiated samples. Silver thin films are deposited on NPA medical device samples using 4[Formula: see text]keV argon ion beam. The XRD spectra demonstrated that silver nanoparticles are deposited on NPA medical device substrate. The effects of Ag thin film on gram-positive and gram-negative bacteria are studied.

Ion beam assisted organic chemical vapor etch of magnetic thin films

An ion beam-assisted organic vapor etch process is demonstrated for patterning magnetic metal elements for potential applications in magnetoresistive random access memory devices. A thermodynamic analysis was performed to evaluate the feasibility of a chemical etch process, leading to the selection of acetylacetone (acac) and hexafluoroacetylacetone (hfac) chemistries. First, etching of cobalt and iron in acac and hfac solutions was studied, and it was determined that acac etches Co preferentially over Fe with a Co:Fe selectivity of ∼4, while hfac etches Fe preferentially over Co with an Fe:Co selectivity of ∼40. This motivates the use of acac and hfac to etch Co and Fe, respectively, but the etch rate was, in the gas phase, too small to be considered a viable process. An argon ion beam was employed in between organic vapor exposures and resulted in significant enhancement in the etch rates, suggesting an ion-enhanced chemical etching process is viable for the patterning of these magnetic metal elements.

Ion beam energy dependence of surface and structural properties of amorphous carbon films deposited by IBSD method on Ni–Cu alloy

Abstract

The characteristics of Ta2O5 films deposited by radio frequency pure oxygen ion assisted deposition (RFOIAD) technology

The characteristics of Ta2O5 films deposited by radio frequency pure oxygen ion assisted deposition (RFOIAD) technology were compared to a gas mixture of oxygen and argon (O2/Ar) ion beam assisted deposition experimentally and theoretically, inclusive of optical, electronic, and laser-induced damage resistance. The results showed that the RFOIAD could make removal of the pinholes and oxygen vacancies in the film and increase of the band gap, which resulted in the enhancement of refractive index, breakdown voltage, and the diminution of absorptivity as well as leakage current. The laser induced damage testing suggested that the damage induced damage threshold of the film deposited by RFOIAD could be increased, but the cracks appeared easily due to the concentration of thermal stress. While for the Ta2O5 film deposited using a sputtering gas of the mixtures of oxygen and argon, the porous characteristics were helpful to relief the thermal stress concentration, and the formation of cracks can be avoided.

Chemical Analysis of the Interface in Bulk-Heterojunction Solar Cells by X-ray Photoelectron Spectroscopy Depth Profiling

Despite the wide use of blends combining an organic p-type polymer and molecular fullerene-based electron acceptor, the proper characterization of such bulk heterojunction materials is still challenging. To highlight structure-to-function relations and improve the device performance, advanced tools and strategies need to be developed to characterize composition and interfaces with sufficient accuracy. In this work, high-resolution X-ray photoelectron spectroscopy (XPS) is combined with very low energy argon ion beam sputtering to perform a nondestructive depth profile chemical analysis on full Al/P3HT:PCBM/PEDOT:PSS/ITO (P3HT, poly(3-hexylthiophene); PCBM, [6,6]-phenyl-C61-butyric acid methyl ester; PEDOT, poly(3,4-ethylenedioxythiophene; PSS, polystyrenesulfonate; ITO, indium tin oxide) bulk-heterojunction solar cell device stacks. Key information, such as P3HT and PCBM composition profiles and Al-PCBM chemical bonding, are deduced in this basic device structure. The interface chemical analysis allows us to evidence, with unprecedented accuracy, the inhomogeneous distribution of PCBM, characterized by a strong segregation toward the top metal electrode. The chemical analysis high-resolution spectra allows us to reconstruct P3HT/PCBM ratio through the active layer depth and correlate with the device deposition protocol and performance. Results evidence an inhomogeneous P3HT/PCBM ratio and poorly controllable PCBM migration, which possibly explains the limited light-to-power conversion efficiency in this basic device structure. The work illustrates the high potential of XPS depth profile analysis for studying such organic/inorganic device stacks.

Interconnections between Ag- NWs Build by Argon Ions Beam Irradiation

Interconnections between Ag- NWs Build by Argon Ions Beam Irradiation Interconnection between Ag-NWs is essential for the integration and assembly of NWs networks to enable optoelectronics and nanoelectronics applications. In this report, joining of Ag-NWs through argon ion beam irradiation technology is demonstrated. A range of experimental traits of constructing X-, and II-shapes molecular junctions between Ag nanowires and the utilization of the argon ion beam irradiation induced nanowelding technique to form functional metal NWs networks is conferred. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy results revealed that Ag-NWs are effectively connected to each other on intersecting positions. These networks are optically transparent and crystal structure remained un-damaged. Besides, technical hindrances facing the ion irradiation induced nanowelding technology are also discussed. A perspective is given for using argon ion irradiation induced welding technique for the construction of random networks of well-connected nanowires.