Dual beam organic depth profiling using large argon cluster ion beams

PubMed Central

Holzweber, M; Shard, AG; Jungnickel, H; Luch, A; Unger, WES

2014-01-01

Argon cluster sputtering of an organic multilayer reference material consisting of two organic components, 4,4′-bis[N-(1-naphthyl-1-)-N-phenyl- amino]-biphenyl (NPB) and aluminium tris-(8-hydroxyquinolate) (Alq3), materials commonly used in organic light-emitting diodes industry, was carried out using time-of-flight SIMS in dual beam mode. The sample used in this study consists of a ∽400-nm-thick NPB matrix with 3-nm marker layers of Alq3 at depth of ∽50, 100, 200 and 300 nm. Argon cluster sputtering provides a constant sputter yield throughout the depth profiles, and the sputter yield volumes and depth resolution are presented for Ar-cluster sizes of 630, 820, 1000, 1250 and 1660 atoms at a kinetic energy of 2.5 keV. The effect of cluster size in this material and over this range is shown to be negligible. © 2014 The Authors. Surface and Interface Analysis published by John Wiley & Sons Ltd. PMID:25892830

Sputtering erosion in ion and plasma thrusters

NASA Technical Reports Server (NTRS)

Ray, Pradosh K.

1995-01-01

An experimental set-up to measure low-energy (below 1 keV) sputtering of materials is described. The materials to be bombarded represent ion thruster components as well as insulators used in the stationary plasma thruster. The sputtering takes place in a 9 inch diameter spherical vacuum chamber. Ions of argon, krypton and xenon are used to bombard the target materials. The sputtered neutral atoms are detected by a secondary neutral mass spectrometer (SNMS). Samples of copper, nickel, aluminum, silver and molybdenum are being sputtered initially to calibrate the spectrometer. The base pressure of the chamber is approximately 2 x 10(exp -9) Torr. the primary ion beam is generated by an ion gun which is capable of delivering ion currents in the range of 20 to 500 nA. The ion beam can be focused to a size approximately 1 mm in diameter. The mass spectrometer is positioned 10 mm from the target and at 90 deg angle to the primary ion beam direction. The ion beam impinges on the target at 45 deg. For sputtering of insulators, charge neutralization is performed by flooding the sample with electrons generated from an electron gun. Preliminary sputtering results, methods of calculating the instrument response function of the spectrometer and the relative sensitivity factors of the sputtered elements will be discussed.

Growth of oxide exchange bias layers

DOEpatents

Chaiken, Alison; Michel, Richard P.

1998-01-01

An oxide (NiO, CoO, NiCoO) antiferromagnetic exchange bias layer produced by ion beam sputtering of an oxide target in pure argon (Ar) sputtering gas, with no oxygen gas introduced into the system. Antiferromagnetic oxide layers are used, for example, in magnetoresistive readback heads to shift the hysteresis loops of ferromagnetic films away from the zero field axis. For example, NiO exchange bia layers have been fabricated using ion beam sputtering of an NiO target using Ar ions, with the substrate temperature at 200.degree. C., the ion beam voltage at 1000V and the beam current at 20 mA, with a deposition rate of about 0.2 .ANG./sec. The resulting NiO film was amorphous.

Growth of oxide exchange bias layers

DOEpatents

Chaiken, A.; Michel, R.P.

1998-07-21

An oxide (NiO, CoO, NiCoO) antiferromagnetic exchange bias layer produced by ion beam sputtering of an oxide target in pure argon (Ar) sputtering gas, with no oxygen gas introduced into the system. Antiferromagnetic oxide layers are used, for example, in magnetoresistive readback heads to shift the hysteresis loops of ferromagnetic films away from the zero field axis. For example, NiO exchange bias layers have been fabricated using ion beam sputtering of an NiO target using Ar ions, with the substrate temperature at 200 C, the ion beam voltage at 1000V and the beam current at 20 mA, with a deposition rate of about 0.2 {angstrom}/sec. The resulting NiO film was amorphous. 4 figs.

The quantitative analysis of silicon carbide surface smoothing by Ar and Xe cluster ions

NASA Astrophysics Data System (ADS)

Ieshkin, A. E.; Kireev, D. S.; Ermakov, Yu. A.; Trifonov, A. S.; Presnov, D. E.; Garshev, A. V.; Anufriev, Yu. V.; Prokhorova, I. G.; Krupenin, V. A.; Chernysh, V. S.

2018-04-01

The gas cluster ion beam technique was used for the silicon carbide crystal surface smoothing. The effect of processing by two inert cluster ions, argon and xenon, was quantitatively compared. While argon is a standard element for GCIB, results for xenon clusters were not reported yet. Scanning probe microscopy and high resolution transmission electron microscopy techniques were used for the analysis of the surface roughness and surface crystal layer quality. The gas cluster ion beam processing results in surface relief smoothing down to average roughness about 1 nm for both elements. It was shown that xenon as the working gas is more effective: sputtering rate for xenon clusters is 2.5 times higher than for argon at the same beam energy. High resolution transmission electron microscopy analysis of the surface defect layer gives values of 7 ± 2 nm and 8 ± 2 nm for treatment with argon and xenon clusters.

Surface modification of tantalum pentoxide coatings deposited by magnetron sputtering and correlation with cell adhesion and proliferation in in vitro tests

NASA Astrophysics Data System (ADS)

Zykova, A.; Safonov, V.; Goltsev, A.; Dubrava, T.; Rossokha, I.; Donkov, N.; Yakovin, S.; Kolesnikov, D.; Goncharov, I.; Georgieva, V.

2016-03-01

The effect was analyzed of surface treatment by argon ions on the surface properties of tantalum pentoxide coatings deposited by reactive magnetron sputtering. The structural parameters of the as-deposited coatings were investigated by means of transmission electron microscopy, atomic force microscopy and scanning electron microscopy. X-ray diffraction profiles and X-ray photoelectron spectra were also acquired. The total surface free energy (SFE), the polar, dispersion parts and fractional polarities, were estimated by the Owens-Wendt-Rabel-Kaeble method. The adhesive and proliferative potentials of bone marrow cells were evaluated for both Ta2O5 coatings and Ta2O5 coatings deposited by simultaneous bombardment by argon ions in in vitro tests.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yin Yunpeng; Sawin, Herbert H.

The surface roughness evolutions of single crystal silicon, thermal silicon dioxide (SiO{sub 2}), and low dielectric constant film coral in argon plasma have been measured by atomic force microscopy as a function of ion bombardment energy, ion impingement angle, and etching time in an inductively coupled plasma beam chamber, in which the plasma chemistry, ion energy, ion flux, and ion incident angle can be adjusted independently. The sputtering yield (or etching rate) scales linearly with the square root of ion energy at normal impingement angle; additionally, the angular dependence of the etching yield of all films in argon plasma followedmore » the typical sputtering yield curve, with a maximum around 60 deg. -70 deg. off-normal angle. All films stayed smooth after etching at normal angle but typically became rougher at grazing angles. In particular, at grazing angles the rms roughness level of all films increased if more material was removed; additionally, the striation structure formed at grazing angles can be either parallel or transverse to the beam impingement direction, which depends on the off-normal angle. More interestingly, the sputtering caused roughness evolution at different off-normal angles can be qualitatively explained by the corresponding angular dependent etching yield curve. In addition, the roughening at grazing angles is a strong function of the type of surface; specifically, coral suffers greater roughening compared to thermal silicon dioxide.« less

Industrial ion source technology

NASA Technical Reports Server (NTRS)

Kaufman, H. R.

1976-01-01

A 30 cm electron bombardment ion source was designed and fabricated for micromachining and sputtering applications. This source has a multipole magnetic field that employs permanent magnets between permeable pole pieces. An average ion current density of 1 ma/sq cm with 500 eV argon ions was selected as a design operating condition. The ion beam at this operating condition was uniform and well collimated, with an average variation of plus or minus 5 percent over the center 20 cm of the beam at distances up to 30 cm from the ion source. A variety of sputtering applications were undertaken with a small 10 cm ion source to better understand the ion source requirements in these applications. The results of these experimental studies are also included.

Fluoropolymer Films Deposited by Argon Ion-Beam Sputtering of Polytetrafluoroethylene

NASA Technical Reports Server (NTRS)

Golub, Morton A.; Banks, Bruce A.; Kliss, Mark (Technical Monitor)

1998-01-01

The FT-IR, XPS and UV spectra of fluoropolymer films (SPTFE-I) deposited by argon ion-beam sputtering of polytetrafluoroethylene (PTFE) were obtained and compared with prior corresponding spectra of fluoropolymer films (SPTFE-P) deposited by argon rf plasma sputtering of PTFE. Although the F/C ratios for SPTFE-I and -P (1.63 and 1.51) were similar, their structures were quite different in that there was a much higher concentration of CF2 groups in SPTFE-I than in SPTFE-P, ca. 61 and 33% of the total carbon contents, respectively. The FT-IR spectra reflect that difference, that for SPTFE-I showing a distinct doublet at 1210 and 1150 per centimeter while that for SPTFE-P presents a broad, featureless band at ca. 1250 per centimeter. The absorbance of the 1210-per centimeter band in SPTFE-I was proportional to the thickness of the film, in the range of 50-400 nanometers. The SPTFE-I was more transparent in the UV than SPTFE-P at comparable thickness. The mechanism for SPTFE-I formation likely involves "chopping off" of oligomeric segments of PTFE as an accompaniment to "plasma" polymerization of TFE monomer or other fluorocarbon fragments generated in situ from PTFE on impact with energetic Ar ions. Data are presented for SPTFE-I deposits and the associated Ar(+) bombarded PTFE targets where a fresh target was used for each run or a single target was used for a sequence of runs.

A HiPIMS plasma source with a magnetic nozzle that accelerates ions: application in a thruster

NASA Astrophysics Data System (ADS)

Bathgate, Stephen N.; Ganesan, Rajesh; Bilek, Marcela M. M.; McKenzie, David R.

2017-01-01

We demonstrate a solid fuel electrodeless ion thruster that uses a magnetic nozzle to collimate and accelerate copper ions produced by a high power impulse magnetron sputtering discharge (HiPIMS). The discharge is initiated using argon gas but in a practical device the consumption of argon could be minimised by exploiting the self-sputtering of copper. The ion fluence produced by the HiPIMS discharge was measured with a retarding field energy analyzer (RFEA) as a function of the magnetic field strength of the nozzle. The ion fraction of the copper was determined from the deposition rate of copper as a function of substrate bias and was found to exceed 87%. The ion fluence and ion energy increased in proportion with the magnetic field of the nozzle and the energy of the ions was found to follow a Maxwell-Boltzmann distribution with a directed velocity. The effectiveness of the magnetic nozzle in converting the randomized thermal motion of the ions into a jet was demonstrated from the energy distribution of the ions. The maximum ion exhaust velocity of at least 15.1 km/s, equivalent to a specific impulse of 1543 s was measured which is comparable to existing Hall thrusters and exceeds that of Teflon pulsed plasma thrusters.

Secondary ion formation during electronic and nuclear sputtering of germanium

NASA Astrophysics Data System (ADS)

Breuer, L.; Ernst, P.; Herder, M.; Meinerzhagen, F.; Bender, M.; Severin, D.; Wucher, A.

2018-06-01

Using a time-of-flight mass spectrometer attached to the UNILAC beamline located at the GSI Helmholtz Centre for Heavy Ion Research, we investigate the formation of secondary ions sputtered from a germanium surface under irradiation by swift heavy ions (SHI) such as 5 MeV/u Au by simultaneously recording the mass spectra of the ejected secondary ions and their neutral counterparts. In these experiments, the sputtered neutral material is post-ionized via single photon absorption from a pulsed, intensive VUV laser. After post-ionization, the instrument cannot distinguish between secondary ions and post-ionized neutrals, so that both signals can be directly compared in order to investigate the ionization probability of different sputtered species. In order to facilitate an in-situ comparison with typical nuclear sputtering conditions, the system is also equipped with a conventional rare gas ion source delivering a 5 keV argon ion beam. For a dynamically sputter cleaned surface, it is found that the ionization probability of Ge atoms and Gen clusters ejected under electronic sputtering conditions is by more than an order of magnitude higher than that measured for keV sputtered particles. In addition, the mass spectra obtained under SHI irradiation show prominent signals of GenOm clusters, which are predominantly detected as positive or negative secondary ions. From the m-distribution for a given Ge nuclearity n, one can deduce that the sputtered material must originate from a germanium oxide matrix with approximate GeO stoichiometry, probably due to residual native oxide patches even at the dynamically cleaned surface. The results clearly demonstrate a fundamental difference between the ejection and ionization mechanisms in both cases, which is interpreted in terms of corresponding model calculations.

Tissue response to peritoneal implants

NASA Technical Reports Server (NTRS)

Picha, G. J.

1980-01-01

Peritoneal implants were fabricated from poly 2-OH, ethyl methacrylate (HEMA), polyetherurethane (polytetramethylene glycol 1000 MW, 1,4 methylene disocynate, and ethyl diamine), and untreated and sputter treated polytetrafluoroethylene (PTFE). The sputter treated PTFE implants were produced by an 8 cm diameter argon ion source. The treated samples consisted of ion beam sputter polished samples, sputter etched samples (to produce a microscopic surface cone texture) and surface pitted samples (produced by ion beam sputtering to result in 50 microns wide by 100 microns deep square pits). These materials were implanted in rats for periods ranging from 30 minutes to 14 days. The results were evaluated with regard to cell type and attachment kinetics onto the different materials. Scanning electron microscopy and histological sections were also evaluated. In general the smooth hydrophobic surfaces attracted less cells than the ion etched PTFE or the HEMA samples. The ion etching was observed to enhance cell attachment, multinucleated giant cell (MNGC) formation, cell to cell contact, and fibrous capsule formation. The cell responsed in the case of ion etched PTFE to an altered surface morphology. However, equally interesting was the similar attachment kinetics of HEMA verses the ion etched PTFE. However, HEMA resulted in a markedly different response with no MNGC's formation, minimal to no capsule formation, and sample coverage by a uniform cell layer.

Improving depth resolutions in positron beam spectroscopy by concurrent ion-beam sputtering

NASA Astrophysics Data System (ADS)

John, Marco; Dalla, Ayham; Ibrahim, Alaa M.; Anwand, Wolfgang; Wagner, Andreas; Böttger, Roman; Krause-Rehberg, Reinhard

2018-05-01

The depth resolution of mono-energetic positron annihilation spectroscopy using a positron beam is shown to improve by concurrently removing the sample surface layer during positron beam spectroscopy. During ion-beam sputtering with argon ions, Doppler-broadening spectroscopy is performed with energies ranging from 3 keV to 5 keV allowing for high-resolution defect studies just below the sputtered surface. With this technique, significantly improved depth resolutions could be obtained even at larger depths when compared to standard positron beam experiments which suffer from extended positron implantation profiles at higher positron energies. Our results show that it is possible to investigate layered structures with a thickness of about 4 microns with significantly improved depth resolution. We demonstrated that a purposely generated ion-beam induced defect profile in a silicon sample could be resolved employing the new technique. A depth resolution of less than 100 nm could be reached.

Sputtering effects on mirrors made of different tungsten grades

NASA Astrophysics Data System (ADS)

Voitsenya, V. S.; Ogorodnikova, O. V.; Bardamid, A. F.; Bondarenko, V. N.; Konovalov, V. G.; Lytvyn, P. M.; Marot, L.; Ryzhkov, I. V.; Shtan', A. F.; Skoryk, O. O.; Solodovchenko, S. I.

2018-03-01

Because tungsten (W) is used in present fusion devices and it is a reference material for ITER divertor and possible plasma-facing material for DEMO, we strive to understand the response of different W grades to ion bombardment. In this study, we investigated the behavior of mirrors made of four polycrystalline W grades under long-term ion sputtering. Argon (Ar) and deuterium (D) ions extracted from a plasma were used to investigate the effect of projectile mass on surface modification. Depending on the ion fluence, the reflectance measured at normal incidence was very different for different W grades. The lowest degradation rate of the reflectance was measured for the mirror made of recrystallized W. The highest degradation rate was found for one of the ITER-grade W samples. Pre-irradiation of a mirror with 20-MeV W6+ ions, as simulation of neutron irradiation in ITER, had no noticeable influence on reflectance degradation under sputtering with either Ar or D ions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudeck, P.J.; Harper, J.M.E.; Fryer, P.M.

The copper concentration in aluminum--copper alloys can be altered by ion bombardment during film deposition. We have measured the sputtering yields of aluminum and copper in Al--Cu alloys as a function of the Cu concentration (5--13 at. %) and the angle of ion incidence (0--40/sup 0/ from normal). During deposition, the films were partially resputtered by 500-eV Ar/sup +/ ion bombardment from a Kaufman ion source. We found that the Cu sputtering yield decreases by up to a factor of 10 in the alloy, relative to elemental Cu. The Al sputtering yield remains close to the elemental value. The netmore » effect is a strong preferential sputtering of Al relative to Cu, which enhances the Cu concentration in an ion bombarded film. The Al/Cu sputtering yield ratio for normal incidence ion bombardment ranges from 3 to 5 as a function of Cu concentration. This ratio decreases with increasing angle of incidence to as low as 2 for 40/sup 0/ incident ions. However, since a higher fraction of the film is resputtered from a sloping surface, a higher Cu concentration is found on a sloping surface relative to a flat surface. These results show that in multicomponent film deposition under ion bombardment, the film composition will vary as a function of the surface topography. We will also show how the level of argon left trapped in the films varies inversely with respect to the ion flux.« less

The target material influence on the current pulse during high power pulsed magnetron sputtering

NASA Astrophysics Data System (ADS)

Moens, Filip; Konstantinidis, Stéphanos; Depla, Diederik

2017-10-01

The current-time characteristic during high power pulsed magnetron sputtering is measured under identical conditions for seventeen different target materials. Based on physical processes such as gas rarefaction, ion-induced electron emission, and electron impact ionization, two test parameters were derived that significantly correlate with specific features of the current-time characteristic: i) the peak current is correlated to the momentum transfer between the sputtered material and the argon gas, ii) while the observed current plateau after the peak is connected to the metal ionization rate.

Neutral beam dose and sputtering characteristics in an ion implantation system

NASA Technical Reports Server (NTRS)

Roberts, A. S., Jr.; Ash, R. L.; Berger, M. H.

1973-01-01

A technique and instrument design for calorimetric detection of the neutral atom content of a 60 keV argon ion beam. A beam sampling method is used to measure local heat flux to a small platinum wire at steady state; integration of power density profiles leads to a determination of equivalent neutral beam current. The fast neutral production occurs as a result of charge transfer processes in the region of the beam system between analyzing magnet and beam stop where the pressure remains less than .00001 torr. A description of the neutral beam detector is given in section along with a presentation of results. An elementary analysis of sputter material transport from target to substrate was performed; the analysis relates to semiconductor sputtering.

Surface acoustic wave/silicon monolithic sensor/processor

NASA Technical Reports Server (NTRS)

Kowel, S. T.; Kornreich, P. G.; Nouhi, A.; Kilmer, R.; Fathimulla, M. A.; Mehter, E.

1983-01-01

A new technique for sputter deposition of piezoelectric zinc oxide (ZnO) is described. An argon-ion milling system was converted to sputter zinc oxide films in an oxygen atmosphere using a pure zinc oxide target. Piezoelectric films were grown on silicon dioxide and silicon dioxide overlayed with gold. The sputtered films were evaluated using surface acoustic wave measurements, X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and resistivity measurements. The effect of the sputtering conditions on the film quality and the result of post-deposition annealing are discussed. The application of these films to the generation of surface acoustic waves is also discussed.

Industrial ion source technology. [for ion beam etching, surface texturing, and deposition

NASA Technical Reports Server (NTRS)

Kaufman, H. R.

1977-01-01

Plasma probe surveys were conducted in a 30-cm source to verify that the uniformity in the ion beam is the result of a corresponding uniformity in the discharge-chamber plasma. A 15 cm permanent magnet multipole ion source was designed, fabricated, and demonstrated. Procedures were investigated for texturing a variety of seed and surface materials for controlling secondary electron emission, increasing electron absorption of light, and improved attachment of biological tissue for medical implants using argon and tetrafluoromethane as the working gases. The cross section for argon-argon elastic collisions in the ion-beam energy range was calculated from interaction potentials and permits calculation of beam interaction effects that can determine system pumping requirements. The data also indicate that different optimizations of ion-beam machines will be advantageous for long and short runs, with 1 mA-hr/cm being the rough dividing line for run length. The capacity to simultaneously optimize components in an ion-beam machine for a single application, a capacity that is not evident in competitive approaches such as diode sputtering is emphasized.

Optical and electrical properties of ion beam textured Kapton and Teflon

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Sovey, J. S.

1977-01-01

Results are given for ion beam texturing of polyimide (Kapton) and fluorinated ethylene propylene (Teflon) by means of a 30-cm diam electron bombardment argon ion source. Ion beam-textured Kapton and Teflon surfaces are evaluated for various beam energies, current densities, and exposure times. The optical properties and sheet resistance are measured after each exposure. Provided in the paper are optical spectral data, resistivity measurements, calculated absorptance and emittance measurements, and surface structure SEM micrographs for various exposures to argon ions. It is found that Kapton becomes conducting and Teflon nonconducting when ion beam-textured. Textured Kapton exhibits large changes in the transmittance and solar absorptance, but only slight changes in reflectance. Surface texturing of Teflon may allow better adherence of subsequent sputtered metallic films for a high absorptance value. The results are valuable in spacecraft charging applications.

Stoichiometry of Silicon Dioxide Films Obtained by Ion-Beam Sputtering

NASA Astrophysics Data System (ADS)

Telesh, E. V.; Dostanko, A. P.; Gurevich, O. V.

2018-03-01

The composition of SiOx films produced by ion-beam sputtering (IBS) of silicon and quartz targets were studied by infrared spectrometry. Films with thicknesses of 150-390 nm were formed on silicon substrates. It was found that increase in the partial pressure of oxygen in the working gas, increase in the temperature of the substrate, and the presence of a positive potential on the target during reactive IBS of silicon shifted the main absorption band νas into the high-frequency region and increased the composition index from 1.41 to 1.85. During IBS of a quartz target the stoichiometry of the films deteriorates with increase of the energy of the sputtering argon ions. This may be due to increase of the deposition rate. Increase in the current of the thermionic compensator, increase of the substrate temperature, and addition of oxygen led to the formation of SiOx films with improved stoichiometry.

Low-Energy Sputtering Studies of Boron Nitride with Xenon Ions

NASA Technical Reports Server (NTRS)

Ray, P. K.; Shutthanandan, V.

1999-01-01

Sputtering of boron nitride with xenon ions was investigated using secondary ion (SIMS) and secondary neutral (SNMS) mass spectrometry. The ions generated from the ion gun were incident on the target at an angle of 50' with respect to the surface'normal. The energy of ions ranged from 100 eV to 3 keV. A flood electron gun was used to neutralize the positive charge build-up on the target surface. The intensities of sputtered neutral and charged particles, including single atoms, molecules, and clusters, were measured as a function of ion energy. Positive SIMS spectra were dominated by the two boron isotopes whereas BN- and B- were the two major constituents of the negative SIMS spectra. Nitrogen could be detected only in the SNMS spectra. The intensity-energy curves of the sputtered particles were similar in shape. The knees in P-SIMS and SNMS intensity-energy curves appear at around I keV which is significantly higher that 100 to 200 eV energy range at which knees appear in the sputtering of medium and heavy elements by ions of argon and xenon. This difference in the position of the sputter yield knee between boron nitride and heavier targets is due to the reduced ion energy differences. The isotopic composition of secondary ions of boron were measured by bombarding boron nitride with xenon ions at energies ranging from 100 eV to 1.5 keV using a quadrupole mass spectrometer. An ion gun was used to generate the ion beam. A flood electron gun was used to neutralize the positive charge buildup on the target surface. The secondary ion flux was found to be enriched in heavy isotopes at lower incident ion energies. The heavy isotope enrichment was observed to decrease with increasing primary ion energy. Beyond 350 eV, light isotopes were sputtered preferentially with the enrichment increasing to an asymptotic value of 1.27 at 1.5 keV. The trend is similar to that of the isotopic enrichment observed earlier when copper was sputtered with xenon ions in the same energy range.

Dynamic determination of secondary electron emission using a calorimetric probe in a plasma immersion ion implantation experiment

NASA Astrophysics Data System (ADS)

Haase, Fabian; Manova, Darina; Hirsch, Dietmar; Mändl, Stephan; Kersten, Holger

2018-04-01

A passive thermal probe has been used to detect dynamic changes in the secondary electron emission (SEE). Oxidized and nitrided materials have been studied during argon ion sputtering in a plasma immersion ion implantation process. Identical measurements have been performed for the metallic state with high voltage pulses accelerating nitrogen ions towards the surface, supposedly forming a nitride layer. Energy flux data were combined with scanning electron microscopy images of the surface to obtain information about the actual surface composition as well as trends and changes during the process. Within the measurements, a direct comparison of the SEE within both employed ion species (argon and nitrogen) is possible while an absolute quantification is still open. Additionally, the nominal composition of the investigated oxide and nitride layers does not always correspond to stoichiometric compounds. Nevertheless, the oxides showed a remarkably higher SEE compared to the pure metals, while an indistinct behavior was observed for the nitrides: some higher, some lower than the clean metal surfaces. For the aluminum alloy AlMg3 a complex time dependent evolution was observed with consecutive oxidation/sputtering cycles leading to a very rough surface with a diminished oxide layer, leading to an almost black surface of the metal and non-reproducible changes in the SEE. The presented method is a versatile technique for measuring dynamic changes of the surface for materials commonly used in PVD processes with a time resolution of about 1 min, e.g. magnetron sputtering or HiPIMS, where changes in the target or electrode composition are occurring but cannot be measured directly.

Mechanical and chemical effects of ion-texturing biomedical polymers

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Cenkus, M. A.

1979-01-01

To determine whether sputter etching may provide substantial polymer surface texturing with insignificant changes in chemical and mechanical properties, an 8 cm beam diameter, electron bombardment, argon ion source was used to sputter etch (ion-texture process) nine biomedical polymers. The materials included silicone rubber, 32% carbon impregnated polyolefin, polyoxymethylene, polytetrafluoroethylene, ultrahigh molecular weight (UHMW) polyethylene, UHMW polyethylene with carbon fibers (10%), and several polyurethanes (bioelectric, segmented, and cross linked). Ion textured microtensile specimens of each material except UHMW polyethylene and UHMW polyethylene with 10% carbon fibers were used to determine the effect of ion texturing on tensile properties. Scanning electron microscopy was used to determine surface morphology changes, and electron spectroscopy for chemical analysis was used to analyze the near surface chemical changes that result from ion texturing. Ion energies of 500 eV with beam current densities ranging from 0.08 to 0.19 mA/sq cm were used to ion texture the various materials. Standard microtensile specimens of seven polymers were exposed to a saline environment for 24 hours prior to and during the tensile testing. The surface chemical changes resulting from sputter etching are minimal in spite of the often significant changes in the surface morphology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sills, L.G.

In this study, hydrogenated amorphous silicon carbide thin films were deposited by reactive ion-beam sputtering under varying conditions to determine whether a film's optical properties can be controlled, focusing on refractive index. Using a Kaufman type ion source to sputter a pure silicon target, three distinct series of films were grown. The first series varied the mixture of methane and argon used in the ion-beam. holding all other parameters constant. For the second series the gas mix was fixed, and only the beam energy (beam voltage) was varied. The final series also varied beam energy, but was grown with amore » graphite shield next to the target to reduce metal contamination sputtered from chamber surfaces. Results show the index of refraction increased monotonically with beam energy up to a beam voltage of 1300 volts. Both the second and third series of films followed this trend, but analysis of differences in atomic composition between two series revealed opposite trends for how the silicon to carbon content ratio and refractive index were related. More precise control of the gas flow, and sputtering from only the intended (silicon)target would have reduced experimental errors.« less

A direct-measurement technique for estimating discharge-chamber lifetime. [for ion thrusters

NASA Technical Reports Server (NTRS)

Beattie, J. R.; Garvin, H. L.

1982-01-01

The use of short-term measurement techniques for predicting the wearout of ion thrusters resulting from sputter-erosion damage is investigated. The laminar-thin-film technique is found to provide high precision erosion-rate data, although the erosion rates are generally substantially higher than those found during long-term erosion tests, so that the results must be interpreted in a relative sense. A technique for obtaining absolute measurements is developed using a masked-substrate arrangement. This new technique provides a means for estimating the lifetimes of critical discharge-chamber components based on direct measurements of sputter-erosion depths obtained during short-duration (approximately 1 hr) tests. Results obtained using the direct-measurement technique are shown to agree with sputter-erosion depths calculated for the plasma conditions of the test. The direct-measurement approach is found to be applicable to both mercury and argon discharge-plasma environments and will be useful for estimating the lifetimes of inert gas and extended performance mercury ion thrusters currently under development.

Effects of 200 keV Ar-ions irradiation on the structural and optical properties of reactively sputtered CrN films

NASA Astrophysics Data System (ADS)

Novaković, M.; Popović, M.; Zhang, K.; Rakočević, Z.; Bibić, N.

2016-12-01

Modification in structural and optical properties of chromium-nitride (CrN) films induced by argon ion irradiation and thermal annealings were investigated using various experimental techniques. CrN films deposited by d. c. reactive sputtering on Si substrate were implanted with 200 keV argon ions, at fluences of 5-20 × 1015 ions/cm2. As-implanted samples were then annealed in vacuum, for 2 h at 700 °C. Rutherford backscattering spectrometry, X-ray diffraction, cross-sectional (high-resolution) transmission electron microscopy and spectroscopic ellipsometry (SE) measurements were carried out in order to study structural and optical properties of the layers. After irradiation with 200 keV Ar ions a damaged surface layer of nanocrystalline structure was generated, which extended beyond the implantation profile, but left an undamaged bottom zone. Partial loss of columnar structure observed in implanted samples was recovered after annealing at 700 °C and CrN started to decompose to Cr2N. This layer geometry determined from transmission electron microscopy was inferred in the analysis of SE data using the combined Drude and Tauc-Lorentz model, and the variation of the optical bandgap was deduced. The results are discussed on the basis of the changes induced in the microstructure. It was found that the optical properties of the layers are strongly dependent on the defects' concentration of CrN.

Dual-ion-beam deposition of carbon films with diamond-like properties

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Swec, D. M.; Angus, J. C.

1985-01-01

A single and dual ion beam system was used to generate amorphous carbon films with diamond like properties. A methane/argon mixture at a molar ratio of 0.28 was ionized in the low pressure discharge chamber of a 30-cm-diameter ion source. A second ion source, 8 cm in diameter was used to direct a beam of 600 eV Argon ions on the substrates (fused silica or silicon) while the deposition from the 30-cm ion source was taking place. Nuclear reaction and combustion analysis indicate H/C ratios for the films to be 1.00. This high value of H/C, it is felt, allowed the films to have good transmittance. The films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Although the measured density of the films was approximately 1.8 gm/cu cm, a value lower than diamond, the films exhibited other properties that were relatively close to diamond. These films were compared with diamond like films generated by sputtering a graphite target.

Dual ion beam deposition of carbon films with diamondlike properties

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Swec, D. M.; Angus, J. C.

1984-01-01

A single and dual ion beam system was used to generate amorphous carbon films with diamond like properties. A methane/argon mixture at a molar ratio of 0.28 was ionized in the low pressure discharge chamber of a 30-cm-diameter ion source. A second ion source, 8 cm in diameter was used to direct a beam of 600 eV Argon ions on the substrates (fused silica or silicon) while the deposition from the 30-cm ion source was taking place. Nuclear reaction and combustion analysis indicate H/C ratios for the films to be 1.00. This high value of H/C, it is felt, allowed the films to have good transmittance. The films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Although the measured density of the films was approximately 1.8 gm/cu cm, a value lower than diamond, the films exhibited other properties that were relatively close to diamond. These films were compared with diamondlike films generated by sputtering a graphite target.

Effects of 200 keV argon ions irradiation on microstructural properties of titanium nitride films

NASA Astrophysics Data System (ADS)

Popović, M.; Novaković, M.; Šiljegović, M.; Bibić, N.

2012-05-01

This paper reports on a study of microstructrual changes in TiN/Si bilayers due to 200 keV Ar+ ions irradiation at room temperature. The 240 nm TiN/Si bilayers were prepared by d.c. reactive sputtering on crystalline Si (1 0 0) substrates. The TiN films were deposited at the substrate temperature of 150 °C. After deposition the TiN/Si bilayers were irradiated to the fluences of 5 × 1015 and 2 × 1016 ions/cm2. The structural changes induced by ion irradiation in the TiN/Si bilayers were analyzed by Rutherford Backscattering Spectroscopy (RBS), X-ray diffraction analyses (XRD) and Transmission Electron Microscopy (TEM). The irradiations caused the microstructrual changes in TiN layers, but no amorphization even at the highest argon fluence of 2 × 1016 ions/cm2. It is also observed that the mean crystallite size decreases with the increasing ion fluence.

Surface structuring in polypropylene using Ar+ beam sputtering: Pattern transition from ripples to dot nanostructures

NASA Astrophysics Data System (ADS)

Goyal, Meetika; Aggarwal, Sanjeev; Sharma, Annu; Ojha, Sunil

2018-05-01

Temporal variations in nano-scale surface morphology generated on Polypropylene (PP) substrates utilizing 40 keV oblique argon ion beam have been presented. Due to controlled variation of crucial beam parameters i.e. ion incidence angle and erosion time, formation of ripple patterns and further its transition into dot nanostructures have been realized. Experimental investigations have been supported by evaluation of Bradley and Harper (B-H) coefficients estimated using SRIM (The Stopping and Range of Ions in Matter) simulations. Roughness of pristine target surfaces has been accredited to be a crucial factor behind the early time evolution of nano-scale patterns over the polymeric surface. Study of Power spectral density (PSD) spectra reveals that smoothing mechanism switch from ballistic drift to ion enhanced surface diffusion (ESD) which can be the most probable cause for such morphological transition under given experimental conditions. Compositional analysis and depth profiling of argon ion irradiated specimens using Rutherford Backscattering Spectroscopy (RBS) has also been correlated with the AFM findings.

Effect of nanoconfinement on the sputter yield in ultrathin polymeric films: Experiments and model

NASA Astrophysics Data System (ADS)

Cristaudo, Vanina; Poleunis, Claude; Delcorte, Arnaud

2018-06-01

This fundamental contribution on secondary ion mass spectrometry (SIMS) polymer depth-profiling by large argon clusters investigates the dependence of the sputter yield volume (Y) on the thickness (d) of ultrathin films as a function of the substrate nature, i.e. hard vs soft. For this purpose, thin films of polystyrene (PS) oligomers (∼4,000 amu) are spin-coated, respectively, onto silicon and poly (methyl methacrylate) supports and, then, bombarded by 10 keV Ar3000+ ions. The investigated thickness ranges from 15 to 230 nm. Additionally, the influence of the polymer molecular weight on Y(d) for PS thin films on Si is explored. The sputtering efficiency is found to be strongly dependent on the overlayer thickness, only in the case of the silicon substrate. A simple phenomenological model is proposed for the description of the thickness influence on the sputtering yield. Molecular dynamics (MD) simulations conducted on amorphous films of polyethylene-like oligomers of increasing thickness (from 2 to 20 nm), under comparable cluster bombardment conditions, predict a significant increase of the sputtering yield for ultrathin layers on hard substrates, induced by energy confinement in the polymer, and support our phenomenological model.

Advanced capabilities and applications of a sputter-RBS system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brijs, B.; Deleu, J.; Beyer, G.

1999-06-10

In previous experiments, sputter-RBS{sup 1} has proven to be an ideal tool to study the interaction of low energy ions. This contribution employs the same methodology to identify surface contamination induced during sputtering and to the determine absolute sputter yields. In the first experiment ERDA analysis was used to study the evolution of Hydrogen contamination during sputter-RBS experiments. Since the determination of Hydrogen concentration in very thin near surface layers is frequently limited by the presence of a strong surface peak of Hydrogen originating from adsorbed contamination of the residual vacuum, removal of this contamination would increase the sensitivity formore » Hydrogen detection in the near sub surface drastically. Therefore low energy (12 keV) Argon sputtering was used to remove the Hydrogen surface peak. However enhanced Hydrogen adsorption was observed related to the Ar dose. This experiment shows that severe vacuum conditions and the use of high current densities/sputter yields are a prerequisite for an efficient detection of Hydrogen in the near surface layers. In the second experiment, an attempt was made to determine the sputter yield of Cu during low energy (12 keV) Oxygen bombardment. In order to determine the accumulated dose of the low energy ion beam, a separate Faraday cup in combination with a remote controlled current have been added to the existing sputter-RBS set-up. Alternating sputtering and RBS analysis seem to be an adequate tool for the determination of the absolute sputter yield of Cu and this as well in the as under steady state conditions.« less

Construction and evaluation of an ultrahigh-vacuum-compatible sputter deposition source

NASA Astrophysics Data System (ADS)

Lackner, Peter; Choi, Joong Il Jake; Diebold, Ulrike; Schmid, Michael

2017-10-01

A sputter deposition source for the use in ultrahigh vacuum (UHV) is described, and some properties of the source are analyzed. The operating principle is based on the design developed by Mayr et al. [Rev. Sci. Instrum. 84, 094103 (2013)], where electrons emitted from a filament ionize argon gas and the Ar+ ions are accelerated to the target. In contrast to the original design, two grids are used to direct a large fraction of the Ar+ ions to the target, and the source has a housing cooled by liquid nitrogen to reduce contaminations. The source has been used for the deposition of zirconium, a material that is difficult to evaporate in standard UHV evaporators. At an Ar pressure of 9 ×1 0-6 mbar in the UHV chamber and moderate emission current, a highly reproducible deposition rate of ≈1 ML in 250 s was achieved at the substrate (at a distance of ≈50 mm from the target). Higher deposition rates are easily possible. X-ray photoelectron spectroscopy shows a high purity of the deposited films. Depending on the grid voltages, the substrate gets mildly sputtered by Ar+ ions; in addition, the substrate is also reached by electrons from the negatively biased sputter target.

Characterization of TiCN coatings deposited by magnetron sputter-ion plating process: RBS and GDOS complementary analyses

NASA Astrophysics Data System (ADS)

Freire, F. L., Jr.; Senna, L. F.; Achete, C. A.; Hirsch, T.

1998-03-01

Hard TiCN films were deposited by dc-magnetron sputter-ion plating technique onto high-speed carbon steel S-6-5-2 (M 2). For selected deposition conditions, TiCN films were also deposited onto Si substrates. A Ti target was sputtered in ArCH 4N 2 atmosphere. The argon flux (12 sccm) was fixed and corresponds to 90% of the total flux, whereas the N 2 flux ranged from 3% to 9% of the total flux. The total pressure in the chamber during film deposition was 8-9 × 10 -2Pa. The substrate bias, Vb, was between 0 and -140V and the substrate temperature, Ts, was 350°C. Film composition and depth profile of the elements were obtained by Rutherford backscattering spectrometry (RBS) and glow discharge optical spectroscopy (GDOS). Some limitations of both techniques in analysing TiCN films were presented. The effect of methane poisoing of the Ti target and how it influences the film composition was discussed.

Techniques for improving material fidelity and contrast consistency in secondary electron mode helium ion microscope (HIM) imaging

NASA Astrophysics Data System (ADS)

Thompson, William; Stern, Lewis; Ferranti, Dave; Huynh, Chuong; Scipioni, Larry; Notte, John; Sanford, Colin

2010-06-01

Recent helium ion microscope (HIM) imaging studies have shown the strong sensitivity of HIM induced secondary electron (SE) yields [1] to the sample physical and chemical properties and to its surface topography. This SE yield sensitivity is due to the low recoil energy of the HIM initiated electrons and their resulting short mean free path. Additionally, a material's SE escape probability is modulated by changes in the material's work function and surface potential. Due to the escape electrons' roughly 2eV mean energy and their nanometer range mean free path, HIM SE mode image contrast has significant material and surface sensitivity. The latest generation of HIM has a 0.35 nanometer resolution specification and is equipped with a plasma cleaning process to mitigate the effects of hydrocarbon contamination. However, for surfaces that may have native oxide chemistries influencing the secondary electron yield, a new process of low energy, shallow angle argon sputtering, was evaluated. The intent of this work was to study the effect of removing pre-existing native oxides and any in-situ deposited surface contaminants. We will introduce the sputter yield predictions of two established computer models and the sputter yield and sample modification forecasts of the molecular dynamics program, Kalypso. We will review the experimental technique applied to copper samples and show the copper grain contrast improvement that resulted when argon cleaned samples were imaged in HIM SE mode.

Morphological transitions in nanoscale patterns produced by concurrent ion sputtering and impurity co-deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, R. Mark

2016-04-07

We modify the theory of nanoscale patterns produced by ion bombardment with concurrent impurity deposition to take into account the effect that the near-surface impurities have on the collision cascades. As the impurity concentration is increased, the resulting theory successively yields a flat surface, a rippled surface with its wavevector along the projected direction of ion incidence, and a rippled surface with its wavevector rotated by 90°. Exactly the same morphological transitions were observed in recent experiments in which silicon was bombarded with an argon ion beam and gold was co-deposited [Moon et al., e-print arXiv:1601.02534].

Effects of nitrogen ion implantation time on tungsten films deposited by DC magnetron sputtering on AISI 410 martensitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malau, Viktor, E-mail: malau@ugm.ac.id; Ilman, Mochammad Noer, E-mail: noer-ilman@yahoo.com; Iswanto, Priyo Tri, E-mail: priyatri@yahoo.com

Nitrogen ion implantation time on tungsten thin film deposited on surface of AISI 410 steel has been performed. Tungsten thin film produced by dc magnetron sputtering method was deposited on AISI 410 martensitic stainless steel substrates, and then the nitrogen ions were implanted on tungsten thin film. The objective of this research is to investigate the effects of implantation deposition time on surface roughness, microhardness, specific wear and corrosion rate of nitrogen implanted on tungsten film. Magnetron sputtering process was performed by using plasma gas of argon (Ar) to bombardier tungsten target (W) in a vacuum chamber with a pressuremore » of 7.6 x 10{sup −2} torr, a voltage of 300 V, a sputter current of 80 mA for sputtered time of 10 minutes. Nitrogen implantation on tungsten film was done with an initial pressure of 3x10{sup −6} mbar, a fluence of 2 x 10{sup 17} ions/cm{sup 2}, an energy of 100 keV and implantation deposition times of 0, 20, 30 and 40 minutes. The surface roughness, microhardness, specific wear and corrosion rate of the films were evaluated by surfcorder test, Vickers microhardness test, wear test and potentiostat (galvanostat) test respectively. The results show that the nitrogen ions implanted deposition time on tungsten film can modify the surface roughness, microhardness, specific wear and corrosion rate. The minimum surface roughness, specific wear and corrosion rate can be obtained for implantation time of 20 minutes and the maximum microhardness of the film is 329 VHN (Vickers Hardness Number) for implantation time of 30 minutes. The specific wear and corrosion rate of the film depend directly on the surface roughness.« less

Measurement Of Hydrogen Capacities And Stability In Thin Films Of AlH Deposited By Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Dissanayake, A.; AlFaify, S.; Garratt, E.; Nandasiri, M. I.; Taibu, R.; Tecos, G.; Hamdan, N. M.; Kayani, A.

2011-06-01

Thin, hydrogenated aluminum hydride films were deposited on silicon substrates using unbalanced magnetron (UBM) sputtering of a high purity aluminum target under electrically grounded conditions. Argon was used as sputtering gas and hydrogenation was carried out by diluting the growth plasma with hydrogen. The effect of hydrogen partial pressure on the final concentration of trapped elements including hydrogen has been studied using ion beam analysis (IBA) techniques. Moreover, in-situ thermal stability of trapped hydrogen in the film was carried out using Rutherford Backscattering Spectrometry (RBS), Non-Rutherford Backscattering Spectrometry (NRBS) and Elastic Recoil Detection Analysis (ERDA). Microstructure of the film was investigated by SEM analysis. Hydrogen content in the thin films was found decreasing as the films were heated above 110 °C in vacuum.

Numerical investigation of depth profiling capabilities of helium and neon ions in ion microscopy

PubMed Central

Rzeznik, Lukasz; Wirtz, Tom

2016-01-01

The analysis of polymers by secondary ion mass spectrometry (SIMS) has been a topic of interest for many years. In recent years, the primary ion species evolved from heavy monatomic ions to cluster and massive cluster primary ions in order to preserve a maximum of organic information. The progress in less-damaging sputtering goes along with a loss in lateral resolution for 2D and 3D imaging. By contrast the development of a mass spectrometer as an add-on tool for the helium ion microscope (HIM), which uses finely focussed He+ or Ne+ beams, allows for the analysis of secondary ions and small secondary cluster ions with unprecedented lateral resolution. Irradiation induced damage and depth profiling capabilities obtained with these light rare gas species have been far less investigated than ion species used classically in SIMS. In this paper we simulated the sputtering of multi-layered polymer samples using the BCA (binary collision approximation) code SD_TRIM_SP to study preferential sputtering and atomic mixing in such samples up to a fluence of 1018 ions/cm2. Results show that helium primary ions are completely inappropriate for depth profiling applications with this kind of sample materials while results for neon are similar to argon. The latter is commonly used as primary ion species in SIMS. For the two heavier species, layers separated by 10 nm can be distinguished for impact energies of a few keV. These results are encouraging for 3D imaging applications where lateral and depth information are of importance. PMID:28144525

CO2 Cluster Ion Beam, an Alternative Projectile for Secondary Ion Mass Spectrometry

NASA Astrophysics Data System (ADS)

Tian, Hua; Maciążek, Dawid; Postawa, Zbigniew; Garrison, Barbara J.; Winograd, Nicholas

2016-09-01

The emergence of argon-based gas cluster ion beams for SIMS experiments opens new possibilities for molecular depth profiling and 3D chemical imaging. These beams generally leave less surface chemical damage and yield mass spectra with reduced fragmentation compared with smaller cluster projectiles. For nanoscale bioimaging applications, however, limited sensitivity due to low ionization probability and technical challenges of beam focusing remain problematic. The use of gas cluster ion beams based upon systems other than argon offer an opportunity to resolve these difficulties. Here we report on the prospects of employing CO2 as a simple alternative to argon. Ionization efficiency, chemical damage, sputter rate, and beam focus are investigated on model compounds using a series of CO2 and Ar cluster projectiles (cluster size 1000-5000) with the same mass. The results show that the two projectiles are very similar in each of these aspects. Computer simulations comparing the impact of Ar2000 and (CO2)2000 on an organic target also confirm that the CO2 molecules in the cluster projectile remain intact, acting as a single particle of m/z 44. The imaging resolution employing CO2 cluster projectiles is improved by more than a factor of two. The advantage of CO2 versus Ar is also related to the increased stability which, in addition, facilitates the operation of the gas cluster ion beams (GCIB) system at lower backing pressure.

Are the argon metastables important in high power impulse magnetron sputtering discharges?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gudmundsson, J. T., E-mail: tumi@hi.is; Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik; Lundin, D.

2015-11-15

We use an ionization region model to explore the ionization processes in the high power impulse magnetron sputtering (HiPIMS) discharge in argon with a titanium target. In conventional dc magnetron sputtering (dcMS), stepwise ionization can be an important route for ionization of the argon gas. However, in the HiPIMS discharge stepwise ionization is found to be negligible during the breakdown phase of the HiPIMS pulse and becomes significant (but never dominating) only later in the pulse. For the sputtered species, Penning ionization can be a significant ionization mechanism in the dcMS discharges, while in the HiPIMS discharge Penning ionization ismore » always negligible as compared to electron impact ionization. The main reasons for these differences are a higher plasma density in the HiPIMS discharge, and a higher electron temperature. Furthermore, we explore the ionization fraction and the ionized flux fraction of the sputtered vapor and compare with recent experimental work.« less

Detrapping of tungsten nanoparticles in a direct-current argon glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Couëdel, L., E-mail: lenaic.couedel@univ-amu.fr; Kumar, K. Kishor; Arnas, C.

2014-12-15

Nanoparticles are grown from the sputtering of a tungsten cathode in a direct current argon glow discharge. Laser light scattering of a vertical laser sheet going through the plasma reveals that the dust particle cloud is compressed and pushed towards the anode during the discharge. Scanning electron microscopy images of substrates exposed to the plasma for given durations show that dust particles are continuously falling down on the anode during the discharge. These observations are explained by the fact that the electrostatic force at the negative glow-anode sheath boundary cannot balance the ion drag, gravity, and thermophoresis forces for particlesmore » of more than a few tens of nanometres in diameter.« less

Radiation-induced deposition of transparent conductive tin oxide coatings

NASA Astrophysics Data System (ADS)

Umnov, S.; Asainov, O.; Temenkov, V.

2016-04-01

The study of tin oxide films is stimulated by the search for an alternative replacement of indium-tin oxide (ITO) films used as transparent conductors, oxidation catalysts, material gas sensors, etc. This work was aimed at studying the influence of argon ions irradiation on optical and electrical characteristics of tin oxide films. Thin films of tin oxide (without dopants) were deposited on glass substrates at room temperature using reactive magnetron sputtering. After deposition, the films were irradiated with an argon ion beam. The current density of the beam was (were) 2.5 mA/cm2, and the particles energy was 300-400 eV. The change of the optical and electrical properties of the films depending on the irradiation time was studied. Films optical properties were investigated by photometry in the range of 300-1100 nm. Films structural properties were studied using 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 has been found that the transmission increases proportionally with the irradiation time, however the sheet resistance increases disproportionally. Tin oxide films (thickness ~30 nm) with ~100% transmittance and sheet resistance of ~100 kOhm/sq. were obtained. The study has proved to be prospective in the use of ion beams to improve the properties of transparent conducting oxides.

Surface ripple evolution by argon ion irradiation in polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goyal, Meetika; Aggarwal, Sanjeev, E-mail: write2sa@gmail.com; Sharma, Annu

In this report, an attempt has been made to investigate the morphological evolution of nanoscale surface ripples on aliphatic (polypropylene, PP) and aromatic (polyethylene terephthalate, PET) polymeric substrates irradiated with 50 keV Ar{sup +} ions. The specimens were sputtered at off normal incidence of 30° with 5 × 10{sup 16} Ar{sup +} cm{sup −2}. The topographical features and structural behavior of the specimens were studied using Atomic Force Microscopy (AFM) and UV-Visible spectroscopy techniques, respectively. The Stopping and Range of Ions in Matter simulations were performed to calculate sputtering yield of irradiated PP and PET polymers. Sputtering yield of carbon atoms has beenmore » found to be smaller for PP (0.40) as compared to PET (0.73), which is attributed to the different structures of two polymers. AFM analysis demonstrates the evolution of ripple like features with amplitude (2.50 nm) and wavelength (690 nm) on PET while that of lower amplitude (1.50 nm) and higher wavelength (980 nm) on PP specimen. The disorder parameter (Urbach energy) has been found to increase significantly from 0.30 eV to 1.67 eV in case of PP as compared to a lesser increase from 0.35 eV to 0.72 eV in case of PET as revealed by UV-Visible characterization. A mutual correlation between ion beam sputtering induced topographical variations with that of enhancement in the disorder parameter of the specimens has been discussed.« less

Spectroellipsometric detection of silicon substrate damage caused by radiofrequency sputtering of niobium oxide

NASA Astrophysics Data System (ADS)

Lohner, Tivadar; Serényi, Miklós; Szilágyi, Edit; Zolnai, Zsolt; Czigány, Zsolt; Khánh, Nguyen Quoc; Petrik, Péter; Fried, Miklós

2017-11-01

Substrate surface damage induced by deposition of metal atoms by radiofrequency (rf) sputtering or ion beam sputtering onto single-crystalline silicon (c-Si) surface has been characterized earlier by electrical measurements. The question arises whether it is possible to characterize surface damage using spectroscopic ellipsometry (SE). In our experiments niobium oxide layers were deposited by rf sputtering on c-Si substrates in gas mixture of oxygen and argon. Multiple angle of incidence spectroscopic ellipsometry measurements were performed, a four-layer optical model (surface roughness layer, niobium oxide layer, native silicon oxide layer and ion implantation-amorphized silicon [i-a-Si] layer on a c-Si substrate) was created in order to evaluate the spectra. The evaluations yielded thicknesses of several nm for the i-a-Si layer. Better agreement could be achieved between the measured and the generated spectra by inserting a mixed layer (with components of c-Si and i-a-Si applying the effective medium approximation) between the silicon oxide layer and the c-Si substrate. High depth resolution Rutherford backscattering (RBS) measurements were performed to investigate the interface disorder between the deposited niobium oxide layer and the c-Si substrate. Atomic resolution cross-sectional transmission electron microscopy investigation was applied to visualize the details of the damaged subsurface region of the substrate.

Endurance test of a 30-CM-diameter engineering model ion thruster. Task 12: Investigation of thin-film erosion monitors for ion thrusters

NASA Technical Reports Server (NTRS)

Beattie, J. R.

1983-01-01

An investigation of short term measurement techniques for predicting the wearout of ion thrusters resulting from sputter erosion damage is described. The previously established laminar thin film techniques to provide high precision erosion rate data. However, the erosion rates obtained using this technique are generally substantially higher than those obtained during long term endurance tests (by virtue of the as deposited nature of the thin films), so that the results must be interpreted in a relative sense. Absolute measurements can be performed using a new masked substrate arrangement which was developed during this study. This new technique provides a means for estimating the lifetimes of critical discharge chamber components based on direct measurements of sputter erosion depths obtained during short duration (10 hour) tests. The method enables the effects on lifetime of thruster design and operating parameters to be inferred without the investment of the time and capital required to conduct long term (1000 hour) endurance tests. Results obtained using the direct measurement technique are shown to agree with sputter erosion depths calculated for the plasma conditions of the test and also with lifetest results. The direct measurement approach is shown to be applicable to both mercury and argon discharge plasma environments and should be useful in estimating the lifetimes of inert gas and extended performance mercury ion thrusters presently under development.

CO2 Cluster Ion Beam, an Alternative Projectile for Secondary Ion Mass Spectrometry.

PubMed

Tian, Hua; Maciążek, Dawid; Postawa, Zbigniew; Garrison, Barbara J; Winograd, Nicholas

2016-09-01

The emergence of argon-based gas cluster ion beams for SIMS experiments opens new possibilities for molecular depth profiling and 3D chemical imaging. These beams generally leave less surface chemical damage and yield mass spectra with reduced fragmentation compared with smaller cluster projectiles. For nanoscale bioimaging applications, however, limited sensitivity due to low ionization probability and technical challenges of beam focusing remain problematic. The use of gas cluster ion beams based upon systems other than argon offer an opportunity to resolve these difficulties. Here we report on the prospects of employing CO2 as a simple alternative to argon. Ionization efficiency, chemical damage, sputter rate, and beam focus are investigated on model compounds using a series of CO2 and Ar cluster projectiles (cluster size 1000-5000) with the same mass. The results show that the two projectiles are very similar in each of these aspects. Computer simulations comparing the impact of Ar2000 and (CO2)2000 on an organic target also confirm that the CO2 molecules in the cluster projectile remain intact, acting as a single particle of m/z 44. The imaging resolution employing CO2 cluster projectiles is improved by more than a factor of two. The advantage of CO2 versus Ar is also related to the increased stability which, in addition, facilitates the operation of the gas cluster ion beams (GCIB) system at lower backing pressure. Graphical Abstract ᅟ.

Low-energy ion beam-based deposition of gallium nitride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasquez, M. R., E-mail: mrvasquez@coe.upd.edu.ph; Wada, M.

2016-02-15

An ion source with a remote plasma chamber excited by a 13.56 MHz radio frequency power was used for low-energy broad ion beam extraction. Optical emission spectral analyses showed the sputtering and postionization of a liquid gallium (Ga) target placed in a chamber separated from the source bombarded by argon (Ar) plasma guided by a bent magnetic field. In addition, an E × B probe successfully showed the extraction of low-energy Ga and Ar ion beams using a dual-electrode extractor configuration. By introducing dilute amounts of nitrogen gas into the system, formation of thin Ga-based films on a silicon substratemore » was demonstrated as determined from X-ray diffraction and X-ray reflectivity studies.« less

Investigation of blister formation in sputtered Cu{sub 2}ZnSnS{sub 4} absorbers for thin film solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bras, Patrice, E-mail: patrice.bras@angstrom.uu.se; Sterner, Jan; Platzer-Björkman, Charlotte

2015-11-15

Blister formation in Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films sputtered from a quaternary compound target is investigated. While the thin film structure, composition, and substrate material are not correlated to the blister formation, a strong link between sputtering gas entrapment, in this case argon, and blistering effect is found. It is shown that argon is trapped in the film during sputtering and migrates to locally form blisters during the high temperature annealing. Blister formation in CZTS absorbers is detrimental for thin film solar cell fabrication causing partial peeling of the absorber layer and potential shunt paths in the complete device.more » Reduced sputtering gas entrapment, and blister formation, is seen for higher sputtering pressure, higher substrate temperature, and change of sputtering gas to larger atoms. This is all in accordance with previous publications on blister formation caused by sputtering gas entrapment in other materials.« less

On the road to self-sputtering in high power impulse magnetron sputtering: particle balance and discharge characteristics

NASA Astrophysics Data System (ADS)

Huo, Chunqing; Lundin, Daniel; Raadu, Michael A.; Anders, André; Tomas Gudmundsson, Jon; Brenning, Nils

2014-04-01

The onset and development of self-sputtering (SS) in a high power impulse magnetron sputtering (HiPIMS) discharge have been studied using a plasma chemical model and a set of experimental data, taken with an aluminum target and argon gas. The model is tailored to duplicate the discharge in which the data are taken. The pulses are long enough to include both an initial transient and a following steady state. The model is used to unravel how the internal discharge physics evolves with pulse power and time, and how it is related to features in the discharge current-voltage-time characteristics such as current densities, maxima, kinks and slopes. The connection between the self-sputter process and the discharge characteristics is quantified and discussed in terms of three parameters: a critical target current density Jcrit based on the maximum refill rate of process (argon) gas above the target, an SS recycling factor ΠSS-recycle, and an approximation \\tilde{\\alpha} of the probabilities of ionization of species that come from the target (both sputtered metal and embedded argon atoms). For low power pulses, discharge voltages UD ⩽ 380 V with peak current densities below ≈ 0.2 A cm-2, the discharge is found to be dominated by process gas sputtering. In these pulses there is an initial current peak in time, associated with partial gas rarefaction, which is followed by a steady-state-like plateau in all parameters similar to direct current magnetron sputtering. In contrast, high power pulses, with UD ⩾ 500 V and peak current densities above JD ≈ 1.6 A cm-2, make a transition to a discharge mode where SS dominates. The transition is found not to be driven by process gas rarefaction which is only about 10% at this time. Maximum gas rarefaction is found later in time and always after the initial peak in the discharge current. With increasing voltage, and pulse power, the discharge can be described as following a route where the role of SS increases in four steps: process gas sputtering, gas-sustained SS, self-sustained SS and SS runaway. At the highest voltage, 1000 V, the discharge is very close to, but does not go into, the SS runaway mode. This absence of runaway is proposed to be connected to an unexpected finding: that twice ionized ions of the target species play almost no role in this discharge, not even at the highest powers. This reduces ionization by secondary-emitted energetic electrons almost to zero in the highest power range of the discharge.

Deposition and characterization of vanadium oxide based thin films for MOS device applications

NASA Astrophysics Data System (ADS)

Rakshit, Abhishek; Biswas, Debaleen; Chakraborty, Supratic

2018-04-01

Vanadium Oxide films are deposited on Si (100) substrate by reactive RF-sputtering of a pure Vanadium metallic target in an Argon-Oxygen plasma environment. The ratio of partial pressures of Argon to Oxygen in the sputtering-chamber is varied by controlling their respective flow rates and the resultant oxide films are obtained. MOS Capacitor based devices are then fabricated using the deposited oxide films. High frequency Capacitance-Voltage (C-V) and gate current-gate voltage (I-V) measurements reveal a significant dependence of electrical characteristics of the deposited films on their sputtering deposition parameters mainly, the relative content of Argon/Oxygen in the plasma chamber. A noteworthy change in the electrical properties is observed for the films deposited under higher relative oxygen content in the plasma atmosphere. Our results show that reactive sputtering serves as an indispensable deposition-setup for fabricating vanadium oxide based MOS devices tailor-made for Non-Volatile Memory (NVM) applications.

Ion beam and dual ion beam sputter deposition of tantalum oxide films

NASA Astrophysics Data System (ADS)

Cevro, Mirza; Carter, George

1994-11-01

Ion beam sputter deposition (IBS) and dual ion beam sputter deposition (DIBS) of tantalum oxide films was investigated at room temperature and compared with similar films prepared by e-gun deposition. Optical properties ie refractive index and extinction coefficient of IBS films were determined in the 250 - 1100 nm range by transmission spectrophotometry and at (lambda) equals 632.8 nm by ellipsometry. They were found to be mainly sensitive to the partial pressure of oxygen used as a reactive gas in the deposition process. The maximum value of the refractive index of IBS deposited tantalum oxide films was n equals 2.15 at (lambda) equals 550 nm and the extinction coefficient of order k equals 2 X 10-4. Films deposited by e-gun deposition had refractive index n equals 2.06 at (lambda) equals 550 nm. Films deposited using DIBS ie deposition assisted by low energy Ar and O2 ions (Ea equals 0 - 300 eV) and low current density (Ji equals 0 - 40 (mu) A/cm2) showed no improvement in the optical properties of the films. Preferential sputtering occurred at Ea(Ar) equals 300 eV and Ji equals 20 (mu) A/cm2 and slightly oxygen deficient films were formed. Different bonding states in the tantalum-oxide films were determined by x-ray spectroscopy while composition of the film and contaminants were determined by Rutherford scattering spectroscopy. Tantalum oxide films formed by IBS contained relatively high Ar content (approximately equals 2.5%) originating from the reflected argon neutrals from the sputtering target while assisted deposition slightly increased the Ar content. Stress in the IBS deposited films was measured by the bending technique. IBS deposited films showed compressive stress with a typical value of s equals 3.2 X 109 dyn/cm2. Films deposited by concurrent ion bombardment showed an increase in the stress as a function of applied current density. The maximum was s approximately equals 5.6 X 109 dyn/cm2 for Ea equals 300 eV and Ji equals 35 (mu) A/cm2. All deposited films were amorphous as measured by the x-ray diffraction method.

Ion-beam and dual-ion-beam sputter deposition of tantalum oxide films

NASA Astrophysics Data System (ADS)

Cevro, Mirza; Carter, George

1995-02-01

Ion-beam sputter deposition (IBS) and dual-ion-beam sputter deposition (DIBS) of tantalum oxide films was investigated at room temperature and compared with similar films prepared by e-gun deposition. The optical properties, i.e., refractive index and extinction coefficient, of IBS films were determined in the 250- to 1100-nm range by transmission spectrophotometry and at (lambda) equals 632.8 nm by ellipsometry. They were found to be mainly sensitive to the partial pressure of oxygen used as a reactive gas in the deposition process. The maximum value of the refractive index of IBS deposited tantalum oxide films was n equals 2.15 at (lambda) equals 550 nm and the extinction coefficient of order k equals 2 X 10-4. Films deposited by e-gun deposition had refractive index n 2.06 at (lambda) equals 550 nm. Films deposited using DIBS, i.e., deposition assisted by low energy Ar and O2 ions (Ea equals 0 to 300 eV) and low current density (Ji equals 0 to 40 (mu) A/cm2), showed no improvement in the optical properties of the films. Preferential sputtering occurred at Ea(Ar) equals 300 eV and Ji equals 20 (mu) A/cm2 and slightly oxygen deficient films were formed. Different bonding states in the tantalum-oxide films were determined by x-ray spectroscopy, whereas composition of the film and contaminants were determined by Rutherford backscattering spectroscopy (RBS). Tantalum oxide films formed by IBS contained relatively high Ar content (approximately equals 2.5%) originating from the reflected argon neutrals from the sputtering target whereas assisted deposition slightly increased the Ar content. Stress in the IBS-deposited films was measured by the bending technique. IBS-deposited films showed compressive stress with a typical value of s equals 3.2 X 109 dyn/cm2. Films deposited by concurrent ion bombardment showed an increase in the stress as a function of applied current density. The maximum was s approximately equals 5.6 X 109 dyn/cm2 for Ea equals 300 eV and Ji equals 35 (mu) A/cm2. All deposited films were amorphous as measured by the x-ray diffraction (XRD) method.

Structural analysis of the outermost hair surface using TOF-SIMS with gas cluster ion beam sputtering.

PubMed

Lshikawa, Kazutaka; Okamoto, Masayuki; Aoyagi, Satoka

2016-06-28

A hair cuticle, which consists of flat overlapping scales that surround the hair fiber, protects inner tissues against external stimuli. The outermost surface of the cuticle is covered with a thin membrane containing proteins and lipids called the epicuticle. In a previous study, the authors conducted a depth profile analysis of a hair cuticle's amino acid composition to characterize its multilayer structure. Time-of-flight secondary ion mass spectrometry with a bismuth primary ion source was used in combination with the C60 sputtering technique for the analysis. It was confirmed that the lipids and cysteine-rich layer exist on the outermost cuticle surface, which is considered to be the epicuticle, though the detailed structure of the epicuticle has not been clarified. In this study, depth profile analysis of the cuticle surface was conducted using the argon gas cluster ion beam (Ar-GCIB) sputtering technique, in order to characterize the structure of the epicuticle. The shallow depth profile of the cuticle surface was investigated using an Ar-GCIB impact energy of 5 keV. Compared to the other amino acid peaks rich in the epicuticle, the decay of 18-methyleicosanic acid (18-MEA) thiolate peak was the fastest. This result suggests that the outermost surface of the hair is rich in 18-MEA. In conclusion, our results indicate that the outermost surfaces of cuticles have a multilayer (lipid and protein layers), which is consistent with the previously proposed structure.

Ion and advanced electric thruster research

NASA Technical Reports Server (NTRS)

Wilbur, P. J.

1980-01-01

A phenomenological model of the orificed, hollow cathode based on the field enhanced, thermionic mechanism of electron emission is presented. High frequency oscillations associated with the orificed, hollow cathode are shown to be a consequence of current flow through the cathode orifice. A procedure for Langmuir probing of the hollow cathode discharge and analyzing the resulting probe characteristics is discussed. The results of sputter yield measurements made for molybdenum, tantalum, type 304 stainless steel and copper surfaces being bombarded by low energy argon or mercury ions are also given. The effects of nitrogen and alternated copper layers on the sputter yields of molybdenum, tantalum and 304 stainless steel are also discussed. A dynamic model of electrothermal rocket and ramjet thrusters is developed. The gross performance of these devices is compared to that of an electromagnetic gun for the case of a high acceleration, Earth launch mission. The theoretical performance of electrothermal rockets and ramjets is shown to be comparable to that of the electromagnetic gun.

Thermal stability of trapped hydrogen in amorphous carbon thin films on Si substrate using ion beam scattering

NASA Astrophysics Data System (ADS)

Moore, A.; Tecos, G.; Nandasiri, M. I.; Garratt, E.; Wickey, K. J.; Gao, X.; Kayani, A.

2009-11-01

Unbalanced magnetron sputtering deposition of C-H films has been performed with various levels of negative substrate bias and with a fixed flow rate of hydrogen. Argon was used as a sputtering gas and formed the majority of the gas in the plasma. The effect of hydrogenation on the final concentration of trapped elements and their thermal stability with respect to hydrogen content is studied using ion beam analysis (IBA) techniques. The elemental concentrations of the films were measured in samples deposited on silicon substrates with a 3.3 MeV of He++ beam used to perform Rutherford Backscattering Spectroscopy (RBS), Non-Rutherford backscattering Spectroscopy (NRBS) and Elastic Recoil Detection Analysis (ERDA). Thermal stability with respect to trapped hydrogen in the film has been studied. As the films were heated in-situ in the vacuum using a o non-gassy button heater, hydrogen was found to be decreasing around 400° C.

Fretting wear study of surface modified Ni-Ti shape memory alloy.

PubMed

Tan, L; Crone, W C; Sridharan, K

2002-05-01

A combination of shape memory characteristics, pseudoelasticity, and good damping properties make near-equiatomic nickel-titanium (Ni-Ti) alloy a desirable candidate material for certain biomedical device applications. The alloy has moderately good wear resistance, however, further improvements in this regard would be beneficial from the perspective of reducing wear debris generation, improving biocompatibility, and preventing failure during service. Fretting wear tests of Ni-Ti in both austenitic and martensitic microstructural conditions were performed with the goal of simulating wear which medical devices such as stents may experience during surgical implantation or service. The tests were performed using a stainless steel stylus counter-wearing surface under dry conditions and also with artificial plasma containing 80 g/L albumen protein as lubricant. Additionally, the research explores the feasibility of surface modification by sequential ion implantation with argon and oxygen to enhance the wear characteristics of the Ni-Ti alloy. Each of these implantations was performed to a dose of 3 x 10(17) atom/cm(2) and an energy of 50 kV, using the plasma source ion implantation process. Improvements in wear resistance were observed for the austenitic samples implanted with argon and oxygen. Ion implantation with argon also reduced the surface Ni content with respect to Ti due to differential sputtering rates of the two elements, an effect that points toward improved biocompatibility.

Stability of nano-scaled Ta/Ti multilayers upon argon ion irradiation

NASA Astrophysics Data System (ADS)

Milosavljević, M.; Milinović, V.; Peruško, D.; Grce, A.; Stojanović, M.; Pjević, D.; Mitrić, M.; Kovač, J.; Homewood, K. P.

2011-10-01

The effects of argon ion irradiation on structural changes in Ta/Ti multilayers deposited on Si wafers were investigated. The starting structures consisted of sputter deposited 10 alternate Ta (˜23 nm) and Ti (˜17 nm) layers of a total thickness ˜200 nm. They were irradiated at room temperature with 200 keV Ar +, to the fluences from 5 × 10 15 to 2 × 10 16 ions/cm 2. The projected ion range was around mid-depth of the multilayered structure, and maximum displacements per atom ˜130. It was found that, despite of the relatively heavy ion irradiation, individual nanocrystalline Ta and Ti layers remain unmixed, keeping the same level of interface planarity. The changes observed in the mostly affected region are increase in lateral dimensions of crystal grains in individual layers, and incorporation of bubbles and defects that cause some stretching of the crystal lattice. Absence of interlayer mixing is assigned to Ta-Ti immiscibility (reaction enthalpy Δ H f = +2 kJ/mol). It is estimated that up to ˜5 at.% interface mixing induced directly by collision cascades could be compensated by dynamic demixing due to chemical driving forces in the temperature relaxation regime. The results can be interesting towards developing radiation tolerant materials based on multilayered structures.

Raman and PEELS studies of magnetron sputtered a-C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, S.; Jen, T.M.; Zeng, X.

Amorphous carbon coatings (a-C, a-C:H) of less than 100 nm thick were deposited on KBr pellets and silicon wafer substrate via magnetron sputtering of graphic target in argon, argon/hydrogen and argon/nitrogen atmosphere. Parallel electron energy loss spectroscopy (PEELS) analysis was used to quantify the sp{sup 2}/sp{sup 3} bonding in carbon films. Stand-alone films of amorphous carbon were produced by sputtering onto compressed KBr pellets and then floating off in distilled water for PEELS study. Raman spectroscopy was used to measure the peak intensity ratio of D-band to that of the G-band (I{sub d}/I{sub g}). It shows that higher sp{sup 3}more » fraction often associates with Raman peak ratio I{sub d}/I{sub g}. At the same time, G-band peak position P{sub g} decreases while sp{sup 3} fraction increases.« less

X-ray photoelectron spectroscopy study of radiofrequency-sputtered refractory compound steel interfaces

NASA Technical Reports Server (NTRS)

Wheeler, D. R.; Brainard, W. A.

1978-01-01

Radiofrequency sputtering was used to deposit Mo2C, Mo2B5, and MoSi2 coatings on 440C steel substrates. Both sputter etched and preoxidized substrates were used, and the films were deposited with and without a substrate bias of -300 V. The composition of the coatings was measured as a function of depth by X-ray photoelectron spectroscopy combined with argon ion etching. In the interfacial region there was evidence that bias produced a graded interface in Mo2B5 but not in Mo2C. Oxides of iron and of all film constituents except carbon were presented in all cases but the iron oxide concentration was higher and the layer thicker on the preoxidized substrates. The film and iron oxides were mixed in the MoSi2 and Mo2C films but layered in the Mo2B5 film. The presence of mixed oxides correlates with enhanced film adhesion.

Boron-rich plasma by high power impulse magnetron sputtering of lanthanum hexaboride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oks, Efim M.; Anders, Andre

2012-10-15

Boron-rich plasmas have been obtained using a LaB{sub 6} target in a high power impulse sputtering (HiPIMS) system. The presence of {sup 10}B{sup +}, {sup 11}B{sup +}, Ar{sup 2+}, Ar{sup +}, La{sup 2+}, and La{sup +} and traces of La{sup 3+}, {sup 12}C{sup +}, {sup 14}N{sup +}, and {sup 16}O{sup +} have been detected using an integrated mass and energy spectrometer. Peak currents as low as 20 A were sufficient to obtain plasma dominated by {sup 11}B{sup +} from a 5 cm planar magnetron. The ion energy distribution function for boron exhibits an energetic tail extending over several 10 eV,more » while argon shows a pronounced peak at low energy (some eV). This is in agreement with models that consider sputtering (B, La) and gas supply (from background and 'recycling'). Strong voltage oscillations develop at high current, greatly affecting power dissipation and plasma properties.« less

Investigation of the optical property and structure of WO3 thin films with different sputtering depositions

NASA Astrophysics Data System (ADS)

Chen, Hsi-Chao; Jan, Der-Jun; Chen, Chien-Han; Huang, Kuo-Ting; Lo, Yen-Ming; Chen, Sheng-Hui

2011-09-01

The purpose of this research was to compare the optical properties and structure of tungsten oxide (WO3) thin films that was deposited by different sputtering depositions. WO3 thin films deposited by two different depositions of direct current (DC) magnetron sputtering and pulsed DC sputtering. A 99.95% WO3 target was used as the starting material for these depositions. These WO3 thin films were deposited on the ITO glass, PET and silicon substrate by different ratios of oxygen and argon. A shadow moiré interferometer would be introduced to measure the residual stress for PET substrate. RF magnetron sputtering had the large residual stress than the other's depositions. A Raman spectrum could exhibit the phase of oxidation of WO3 thin film by different depositions. At the ratio of oxygen and argon was about 1:1, and the WO3 thin films had the best oxidation. However, it was important at the change of the transmittance (ΔT = Tbleached - Tcolored) between the coloring and bleaching for the smart window. Therefore, we also found the WO3 thin films had the large variation of transmittance between the coloring and bleaching at the gas ratios of oxygen and argon of 1:1.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panitz, J.K.G.

A homogeneous, micrometer-sized conical surface texture forms on 2% Be-Cu alloy which is bombarded with an argon beam produced by a Kaufman ion source. The dimensions of the features that form strongly depend on: (1) argon energy (from 250 to 1500 eV), (2) fluence (10{sup 19} to 10{sup 20} ions/cm{sup 2}), and (3) flux (0.1 to 1 mA/cm{sup 2}). The texture morphology depends less strongly on the background ambient (Mo vs graphite), earlier alloy heat treatments and the temperature during bombardment (100{degree}C and 450{degree}C). As the texture matures with increasing fluence, the number of large features increases at the expensemore » of the number of small features. The observed relationship between texture formation and ion flux suggests that the evolution of these features is not adequately described by theories predicting that the mature conical sidewall angle is related to the angle of the maximum sputtering yield. These textured surfaces can be coated with other metals for a variety of possible applications including: (1) pulsed power Li+ beam anodes, (2) cold cathode field emission devices, (3) optical absorbers and (4) catalysis supports. 18 refs., 5 figs.« less

Changes in size of nano phase iron inclusions with temperature: Experimental simulation of space weathering effects at high temperature

NASA Astrophysics Data System (ADS)

Rout, S. S.; Moroz, L. V.; Stockhoff, T.; Baither, D.; Bischoff, A.; Hiesinger, H.

2011-10-01

The mean size of nano phase iron inclusions (npFe0), produced during the space weathering of iron-rich regolith of airless solar system bodies, significantly affects visible and near-infrared (VNIR) spectra. To experimentally simulate the change in the size of npFe0 inclusions with increasing temperature, we produced sputter film deposits on a silicon dioxide substrate by sputtering a pressed pellet prepared from fine olivine powder using 600V Ar+ ions. This silicon dioxide substrate covered with the deposit was later heated to 450°C for 24 hours in an oven under argon atmosphere. Initial TEM analysis of the unheated silicon dioxide substrate showed the presence of a ~ 50 nm-thick layer of an amorphous deposit with nano clusters that has not yet been identified.

Sputtering of water ice films: A re-assessment with singly and doubly charged oxygen and argon ions, molecular oxygen, and electrons

NASA Astrophysics Data System (ADS)

Galli, A.; Vorburger, A.; Wurz, P.; Tulej, M.

2017-07-01

We studied the erosion rates from thin water ice films on a microbalance upon irradiation with ions (O+, O2+, O2+ , Ar+ , and Ar2+) and electrons at energies between 0.1 keV and 80 keV. The results with O+ and Ar+ irradiation confirm previous results of other research groups that relied on the same experiment set-up. In addition, we assessed how the ice film thickness affects the results and we compared the results for singly versus doubly charged ions and for O+ versus O2+ ions. The irradiation with 1 keV and 3 keV electrons offer the first experimental results at these energies. Our results confirm theoretical predictions that the yield per impacting electron does not increase with energy ad infinitum but rather levels off between 0.1 and 1 keV. The results for ion and electron sputtering have important implications for atmosphere-less icy bodies in a plasma environment. We briefly discuss the implications for the icy moons of Jupiter. Finally, the experiments also allow us to assess the viability of two methods to measure the erosion rate in the case that the icy sample cannot be attached on a microbalance. This is an important step for future laboratory studies where regolith ice samples and their reaction to particle irradiation are to be characterized.

A review of the use of Al-alloy vacuum components for operation at 10-13 Torr

NASA Astrophysics Data System (ADS)

Ishimaru, Hajime

1990-02-01

An extremely high vacuum (XHV) chamber was fabricated and tested. The vacuum chamber was made of special surface finished (EX-process) aluminum alloy in oxygen and argon atmosphere. The chamber was assembled using TIG welding in an argon atmosphere and by electron beam welding. The system was evacuated with a turbo-backed 300 l/s turbomolecular pump separated from the main chamber using a right angle valve. The liquid nitrogen shroud is installed inside the main vacuum chamber. The XHV is maintained by two 300 l/s sputter ion pumps and a titanium sublimation pump with a liquid nitrogen shroud. These pumps are also made of aluminum alloys. An ultimate pressure of 3×10-13 Torr was measured with a point collector gauge with a spherical anode mounted on an Al-flange. Residual gas analysis in the order 10-13 Torr was performed by a newly developed Q-mass filter. To suppress outgassing from the quadrupole electrode, the ion source is mounted on an Al-flange separated from the quadrupole electrode.

Ion Beam Analysis of the Thermal Stability of Hydrogenated Diamond-Like Carbon Thin Films on Si Substrate

NASA Astrophysics Data System (ADS)

Nandasiri, M. I.; Moore, A.; Garratt, E.; Wickey, K. J.; AlFaify, S.; Gao, X.; Kayani, A.; Ingram, D.

2009-03-01

Unbalanced magnetron sputtering deposition of C-H films has been performed with various levels of negative substrate bias and with a fixed flow rate of hydrogen. Argon was used as a sputtering gas and formed the majority of the gas in the plasma. The effect of hydrogenation on the final concentration of trapped elements and their thermal stability with respect to hydrogen content is studied using ion beam analysis (IBA) techniques. The elemental concentrations of the films were measured in the films deposited on silicon substrates with a 2.5 MeV of H+ beam, which is used to perform Rutherford Backscattering Spectrometry (RBS) and Non-Rutherford Backscattering spectrometry (NRBS) and with 16 MeV of O5+ beam, used to perform Elastic Recoil Detection Analysis (ERDA). Effect of bias on the thermal stability of trapped hydrogen in the films has been studied. As the films were heated in-situ in vacuum using a non-gassy button heater, hydrogen was found to be decreasing around 400° C.

Diffraction limited focusing and routing of gap plasmons by a metal-dielectric-metal lens

DOE PAGES

Dennis, Brian S.; Czaplewski, David A.; Haftel, Michael I.; ...

2015-08-12

Passive optical elements can play key roles in photonic applications such as plasmonic integrated circuits. Here we experimentally demonstrate passive gap-plasmon focusing and routing in two-dimensions. This is accomplished using a high numerical-aperture metal-dielectric-metal lens incorporated into a planar-waveguide device. Fabrication via metal sputtering, oxide deposition, electron- and focused-ion- beam lithography, and argon ion-milling is reported on in detail. Diffraction-limited focusing is optically characterized by sampling out-coupled light with a microscope. The measured focal distance and full-width-half-maximum spot size agree well with the calculated lens performance. The surface plasmon polariton propagation length is measured by sampling light from multiple out-couplermore » slits.« less

An XPS study of the adherence of refractory carbide, silicide, and boride RF-sputtered wear-resistant coatings. [X-ray Photoelectron Spectroscopy of steel surfaces

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1978-01-01

Radio frequency sputtering was used to deposit refractory carbide, silicide, and boride coatings on 440-C steel substrates. Both sputter etched and pre-oxidized substrates were used and the films were deposited with and without a substrate bias. The composition of the coatings was determined as a function of depth by X-ray photoelectron spectroscopy combined with argon ion etching. Friction and wear tests were conducted to evaluate coating adherence. In the interfacial region there was evidence that bias may produce a graded interface for some compounds. Biasing, while generally improving bulk film stoichiometry, can adversely affect adherence by removing interfacial oxide layers. Oxides of all film constituents except carbon and iron were present in all cases but the iron oxide coverage was only complete on the preoxidized substrates. The film and iron oxides were mixed in the MoSi2 and Mo2C films but layered in the Mo2B5 films. In the case of mixed oxides, preoxidation enhanced film adherence. In the layered case it did not.

Effect of Enhanced Thermal Stability of Alumina Support Layer on Growth of Vertically Aligned Single-Walled Carbon Nanotubes and Their Application in Nanofiltration Membranes.

PubMed

In, Jung Bin; Cho, Kang Rae; Tran, Tung Xuan; Kim, Seok-Min; Wang, Yinmin; Grigoropoulos, Costas P; Noy, Aleksandr; Fornasiero, Francesco

2018-06-07

We investigate the thermal stability of alumina supporting layers sputtered at different conditions and its effect on the growth of aligned single-walled carbon nanotube arrays. Radio frequency magnetron sputtering of alumina under oxygen-argon atmosphere produces a Si-rich alumina alloy film on a silicon substrate. Atomic force microscopy on the annealed catalysts reveals that Si-rich alumina films are more stable than alumina layers with low Si content at the elevated temperatures at which the growth of single-walled carbon nanotubes is initiated. The enhanced thermal stability of the Si-rich alumina layer results in a narrower (< 2.2 nm) diameter distribution of the single-walled carbon nanotubes. Thanks to the smaller diameters of their nanotube pores, membranes fabricated with vertically aligned nanotubes grown on the stable layers display improved ion selectivity.

Effect of Enhanced Thermal Stability of Alumina Support Layer on Growth of Vertically Aligned Single-Walled Carbon Nanotubes and Their Application in Nanofiltration Membranes

NASA Astrophysics Data System (ADS)

In, Jung Bin; Cho, Kang Rae; Tran, Tung Xuan; Kim, Seok-Min; Wang, Yinmin; Grigoropoulos, Costas P.; Noy, Aleksandr; Fornasiero, Francesco

2018-06-01

We investigate the thermal stability of alumina supporting layers sputtered at different conditions and its effect on the growth of aligned single-walled carbon nanotube arrays. Radio frequency magnetron sputtering of alumina under oxygen-argon atmosphere produces a Si-rich alumina alloy film on a silicon substrate. Atomic force microscopy on the annealed catalysts reveals that Si-rich alumina films are more stable than alumina layers with low Si content at the elevated temperatures at which the growth of single-walled carbon nanotubes is initiated. The enhanced thermal stability of the Si-rich alumina layer results in a narrower (< 2.2 nm) diameter distribution of the single-walled carbon nanotubes. Thanks to the smaller diameters of their nanotube pores, membranes fabricated with vertically aligned nanotubes grown on the stable layers display improved ion selectivity.

Auger spectroscopy of fracture surfaces of ceramics

NASA Technical Reports Server (NTRS)

Marcus, H. L.; Harris, J. M.; Szalkowski, F. J.

1974-01-01

Results of Auger electron spectroscopy (AES) studies of fracture surfaces in a series of ceramic materials, including Al2O3, MgO, and Si3N4, which were formed using different processing techniques. AES on the fractured surface of a lunar sample is also discussed. Scanning electron micrograph fractography is used to relate the surface chemistry to the failure mode. Combined argon ion sputtering and AES studies demonstrate the local variations in chemistry near the fracture surface. The problems associated with doing AES in insulators are also discussed, and the experimental techniques directed toward solving them are described.

Electronic perturbation investigations into excitation and ionization in the millisecond pulsed glow discharge plasma

NASA Astrophysics Data System (ADS)

Li, Lei; Robertson-Honecker, Jennifer; Vaghela, Vishal; King, Fred L.

2006-06-01

This study employed a power perturbation method to examine the energy transfer processes at different locations within the afterpeak regime of a millisecond pulsed glow discharge plasma. Brief power perturbation pulses were applied during the afterpeak regime altering the environment of the collapsing plasma. Responses of several transitions to the power perturbations were measured via atomic emission and absorption spectroscopic methods at various distances from the surface of the cathode. The experimental data provide further insight into the energy transfer processes that occur at different spatial locations and in different temporal regimes of these pulsed glow discharge plasmas. Although the enhancement of the large population of metastable argon atoms is again confirmed, the mechanism responsible for this enhancement remains unclear. The most likely possibility involves some form of ion-electron recombination followed by radiative relaxation of the resulting species. The metastable argon atoms subsequently Penning ionize sputtered copper atoms which then appear to undergo a similar ion-electron recombination process yielding variable degrees of observable afterpeak emission for copper atom transitions. The kinetic information of these processes was approximated from the corresponding relaxation time. The electron thermalization time allowing for recombination with ions was found to be ˜25 μs after the discharge power termination.

The influence of projectile ion induced chemistry on surface pattern formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karmakar, Prasanta, E-mail: prasantak@vecc.gov.in; Satpati, Biswarup

We report the critical role of projectile induced chemical inhomogeneity on surface nanostructure formation. Experimental inconsistency is common for low energy ion beam induced nanostructure formation in the presence of uncontrolled and complex contamination. To explore the precise role of contamination on such structure formation during low energy ion bombardment, a simple and clean experimental study is performed by selecting mono-element semiconductors as the target and chemically inert or reactive ion beams as the projectile as well as the source of controlled contamination. It is shown by Atomic Force Microscopy, Cross-sectional Transmission Electron Microscopy, and Electron Energy Loss Spectroscopy measurementsmore » that bombardment of nitrogen-like reactive ions on Silicon and Germanium surfaces forms a chemical compound at impact zones. Continuous bombardment of the same ions generates surface instability due to unequal sputtering and non-uniform re-arrangement of the elemental atom and compound. This instability leads to ripple formation during ion bombardment. For Argon-like chemically inert ion bombardment, the chemical inhomogeneity induced boost is absent; as a result, no ripples are observed in the same ion energy and fluence.« less

P-channel transparent thin-film transistor using physical-vapor-deposited NiO layer

NASA Astrophysics Data System (ADS)

Lin, Chiung-Wei; Chung, Wei-Chieh; Zhang, Zhao-De; Hsu, Ming-Chih

2018-01-01

The effect of oxygen (O) content on the electrical properties of physical-vapor-deposited nickel oxide (PVD-NiO) was studied. When the NiO target was sputtered, introducing O2 can lead to the formation of Ni3+ ions in the deposited film. These Ni3+ ions can act as acceptors. However, there were too many Ni3+ ions that were obtained following the introduction of O atoms. It resulted in intensive p-type conduction and made the O2-introduced PVD-NiO behave as a conductor. Thus, it was possible to reduce the O content of PVD-NiO to obtain a p-type semiconductor. In this study, a transparent PVD-NiO film with a carrier concentration of 1.62 × 1017 cm-3 and a resistivity of 3.74 Ω cm was sputter-deposited within pure argon plasma. The thin-film transistor (TFT) employing this proposed PVD-NiO can result in good current switching, and even operated at very low drain-source voltage. The ON/OFF current ratio, field-effect carrier mobility, and threshold voltage of the proposed NiO TFT were 3.61 × 104, 1.09 cm2 V-1 s-1 and -3.31 V, respectively.

Magnetron-Sputtered Amorphous Metallic Coatings

NASA Technical Reports Server (NTRS)

Thakoor, A. P.; Mehra, M.; Khanna, S. K.

1985-01-01

Amorphous coatings of refractory metal/metalloid-based alloys deposited by magnetron sputtering provide extraordinary hardness and wear resistance. Sputtering target fabricated by thoroughly mixing powders of tungsten, rhenium, and boron in stated proportions and pressing at 1,200 degrees C and 3,000 lb/in. to second power (21 MPa). Substrate lightly etched by sputtering before deposition, then maintained at bias of - 500 V during initial stages of film growth while target material sputtered onto it. Argon gas at pressure used as carrier gas for sputter deposition. Coatings dense, pinhole-free, extremely smooth, and significantly resistant to chemical corrosion in acidic and neutral aqueous environments.

Formation of manganese nanoclusters in a sputtering/aggregation source and the roles of individual operating parameters

NASA Astrophysics Data System (ADS)

Khojasteh, Malak; Kresin, Vitaly V.

2016-12-01

We describe the production of size selected manganese nanoclusters using a dc magnetron sputtering/aggregation source. Since nanoparticle production is sensitive to a range of overlapping operating parameters (in particular, the sputtering discharge power, the inert gas flow rates, and the aggregation length) we focus on a detailed map of the influence of each parameter on the average nanocluster size. In this way it is possible to identify the main contribution of each parameter to the physical processes taking place within the source. The discharge power and argon flow supply the atomic vapor, and argon also plays the crucial role in the formation of condensation nuclei via three-body collisions. However, neither the argon flow nor the discharge power have a strong effect on the average nanocluster size in the exiting beam. Here the defining role is played by the source residence time, which is governed by the helium supply and the aggregation path length. The size of mass selected nanoclusters was verified by atomic force microscopy of deposited particles.

Influence of source parameters on the growth of metal nanoparticles by sputter-gas-aggregation

NASA Astrophysics Data System (ADS)

Khojasteh, Malak; Kresin, Vitaly V.

2017-11-01

We describe the production of size-selected manganese nanoclusters using a magnetron sputtering/aggregation source. Since nanoparticle production is sensitive to a range of overlapping operating parameters (in particular, the sputtering discharge power, the inert gas flow rates, and the aggregation length), we focus on a detailed map of the influence of each parameter on the average nanocluster size. In this way, it is possible to identify the main contribution of each parameter to the physical processes taking place within the source. The discharge power and argon flow supply the metal vapor, and argon also plays a crucial role in the formation of condensation nuclei via three-body collisions. However, the argon flow and the discharge power have a relatively weak effect on the average nanocluster size in the exiting beam. Here the defining role is played by the source residence time, governed by the helium supply (which raises the pressure and density of the gas column inside the source, resulting in more efficient transport of nanoparticles to the exit) and by the aggregation path length.

Diamondlike carbon protective coatings for IR materials

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Nir, D.; Swec, D. M.; Banks, B. A.

1985-01-01

Diamondlike carbon (DLC) films have the potential to protect optical windows in applications where it is important to maintain the integrity of the specular transmittance of these films on ZnS and ZnSe infrared transmitting windows. The films must be adherent and durable such that they protect the windows from rain and particle erosion as well as chemical attack. In order to optimize the performance of these films, 0.1 micro m thick diamondlike carbon films were deposited on fused silica and silicon wafers, using three different methods of ion beam deposition. One method was sputter deposition from a carbon target using an 8 cm ion source. The merits of hydrogen addition were experimentally evaluated in conjunction with this method. The second method used a 30 cm hollow cathode ion source with hydrocarbon/Argon gases to deposit diamondlike carbon films from the primary beam at 90 to 250 eV. The third method used a dual beam system employing a hydrocarbon/Argon 30 cm ion source and an 8 cm ion source. Films were evaluated for adherence, intrinsic stress, infrared transmittance between 2.5 and 50 micro m, and protection from particle erosion. An erosion test using a sandblaster was used to give quantitative values of the protection afforded to the fused silica by the diamondlike carbon films. The fused silica surfaces protected by diamondlike carbon films were exposed to 100 micro m diameter SiO particles at 60 mi/hr (26.8/sec) in the sandblaster.

Sputtered silicon nitride coatings for wear protection

NASA Technical Reports Server (NTRS)

Grill, A.; Aron, P. R.

1982-01-01

Silicon nitride films were deposited by RF sputtering on 304 stainless steel substrates in a planar RF sputtering apparatus. The sputtering was performed from a Si3N4 target in a sputtering atmosphere of argon and nitrogen. The rate of deposition, the composition of the coatings, the surface microhardness and the adhesion of the coatings to the substrates were investigated as a function of the process parameters, such as: substrate target distance, fraction nitrogen in the sputtering atmosphere and sputtering pressure. Silicon rich coating was obtained for fraction nitrogen below 0.2. The rate of deposition decreases continuously with increasing fraction nitrogen and decreasing sputtering pressure. It was found that the adherence of the coatings improves with decreasing sputtering pressure, almost independently of their composition.

Focused Ion Beam (FIB) combined with SEM (FIB/SEM) and TEM: Advanced tools for nano-analysis in Geosciences

NASA Astrophysics Data System (ADS)

Wirth, R.; Morales, L. G.

2011-12-01

Focused ion beam (FIB) techniques have been successfully applied to the preparation of site-specific electron transparent membranes for transmission electron microscopy (TEM) investigations in Geosciences since several years. For example, systematic TEM studies of nano-inclusions in diamond foils prepared with FIB have improved our knowledge on diamond formation. However, FIB is not exclusively used for sample preparation for TEM application because it has been proved that one and the same TEM foil can also be used for Synchrotron IR, Synchrotron X-Ray fluorescence (XRF), scanning transmission X-Ray microscopy (STXM) and NanoSIMS analysis. In addition, FIB milling turned out to be very useful for sample preparation of Brillouin scattering experiments and has a strong potential for preparation of highly-polished, micrometer-scale samples. However, a real break through in FIB application was achieved combining a Ga-ion source of the FIB with an electron source of a scanning electron microscope (SEM) in one single instrument. The combination of FIB/SEM renders access to the third dimension of the sample possible. A cavity normal to the sample surface is sputtered with Ga-ions and this newly created inner surface is imaged with the electron beam. Alternating slicing and viewing along these cavities allow the acquisition of a sequence of images that allows the observation in 3 dimensions. Recently, this technique has been successfully applied to image the structure of grain or phase boundaries in metamorphic rocks as well as micro- and nanoporosity in shales, but its applicability goes far beyond these few examples. Combining slicing and viewing with X-Ray and electron backscatter diffraction (EBSD) analysis can provide 3D elemental mapping and 3D crystallographic orientation mapping of crystalline materials. Combined FIB/SEM devices also facilitate the preparation of substantially thinner and cleaner TEM foils (approximately 30 nm) because electron beam imaging controls the progress of the sputtering process without sputtering the sample during imaging. Electron induce sputtering is substantially smaller than ion induced sputtering. Finally, the amorphous layers created by Ga-ion sputtering and Ga-ion implantation can be removed from the foil surfaces by subsequent argon ion bombardment under a low angle of incidence and low acceleration voltage thus permitting TEM high-resolution imaging and electron energy-loss spectroscopy (EELS). Additionally, ultra-thin foils have the advantage that they are electron transparent even at 30 keV, the common operational voltage of a SEM. Therefore the electron column of the FIB/SEM system can be used as a TEM at low voltage and images can be made either in bright-field, dark field and through a high-angle annular dark field (HAADF) detector. The HAADF detector provides information about the chemical composition of the specimen with high spatial resolution because it is Z-contrast sensitive.

Carbon distribution profiles in lunar fines

NASA Technical Reports Server (NTRS)

Hart, R. K.

1977-01-01

Radial distribution profiles of elemental carbon in lunar soils consisting of particles in the size range of 50 to 150 microns were investigated. Initial experiments on specimen preparation and the analysis of prepared specimens by Auger electron spectrometry (AES) and scanning electron microscopy (SEM) are described. Results from splits of samples 61501,84 and 64421,11, which were mounted various ways in several specimen holders, are presented. A low carbon content was observed in AES spectra from soil particles that were subjected to sputter-ion cleaning with 960eV argon ions for periods of time up to a total exposure for one hour. This ion charge was sufficient to remove approximately 70 nm of material from the surface. All of the physically adsorbed carbon (as well as water vapor, etc.) would normally be removed in the first few minutes, leaving only carbon in the specimen, and metal support structure, to be detected thereafter.

Characterization of Sputtered Nickel-Titanium (NiTi) Stress and Thermally Actuated Cantilever Bimorphs Based on NiTi Shape Memory Alloy (SMA)

DTIC Science & Technology

2015-11-01

necessary anneal . Following this, a thin film of NiTi was blanket sputtered at 600 °C. This NiTi blanket layer was then wet -etch patterned using a...varying the sputter parameters during NiTi deposition, such as thickness, substrate temperature during deposition and anneal , and argon pressure during...6 Fig. 4 Surface texture comparison between NiTi sputtered at RT, then annealed at 600 °C, and NiTi

Diffraction limited focusing and routing of gap plasmons by a metal-dielectric-metal lens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dennis, Brian S.; Czaplewski, David A.; Haftel, Michael I.

2015-01-01

Passive optical elements can play key roles in photonic applications such as plasmonic integrated circuits. Here we experimentally demonstrate passive gap-plasmon focusing and routing in two-dimensions. This is accomplished using a high numerical-aperture metal-dielectric-metal lens incorporated into a planar-waveguide device. Fabrication via metal sputtering, oxide deposition, electron-and focused-ion-beam lithography, and argon ion-milling is reported on in detail. Diffraction-limited focusing is optically characterized by sampling out-coupled light with a microscope. The measured focal distance and full-width-half-maximum spot size agree well with the calculated lens performance. The surface plasmon polariton propagation length is measured by sampling light from multiple out-coupler slits. (C)more » 2015 Optical Society of America« less

Study on the effect of hydrogen addition on the variation of plasma parameters of argon-oxygen magnetron glow discharge for synthesis of TiO{sub 2} films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saikia, Partha, E-mail: partha.008@gmail.com; Institute of Physics, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago; Saikia, Bipul Kumar

2016-04-15

We report the effect of hydrogen addition on plasma parameters of argon-oxygen magnetron glow discharge plasma in the synthesis of H-doped TiO{sub 2} films. The parameters of the hydrogen-added Ar/O{sub 2} plasma influence the properties and the structural phases of the deposited TiO{sub 2} film. Therefore, the variation of plasma parameters such as electron temperature (T{sub e}), electron density (n{sub e}), ion density (n{sub i}), degree of ionization of Ar and degree of dissociation of H{sub 2} as a function of hydrogen content in the discharge is studied. Langmuir probe and Optical emission spectroscopy are used to characterize the plasma.more » On the basis of the different reactions in the gas phase of the magnetron discharge, the variation of plasma parameters and sputtering rate are explained. It is observed that the electron and heavy ion density decline with gradual addition of hydrogen in the discharge. Hydrogen addition significantly changes the degree of ionization of Ar which influences the structural phases of the TiO{sub 2} film.« less

Physicochemical variation of mica surface by low energy ion beam irradiation

NASA Astrophysics Data System (ADS)

Bhowmik, Dipak; Karmakar, Prasanta

2018-05-01

We report the transformation of smooth and hydrophilic mica surface to a patterned and hydrophobic surface by 12 keV Ar+ and N+ ion bombardment at oblique ion incidence. Periodic ripple pattern has been found on the mica surface when nitrogen like lighter or argon like heavier ions are bombarded at an angle 60° with respect to the surface normal. During ion bombardment the different components of multi-elemental mica are eroded at different rate; as a result surface chemistry is changed, as well as a surface ripple pattern is developed on the surface due to the generation of surface instabilities. The change of surface chemistry and presence of pattern change the hydrophilic nature of the mica surface. X-ray photoelectron spectroscopy (XPS) study of irradiated mica surface shows that the upper K atoms are sputtered most. The vertical and lateral dimensions of the surface patterns are controlled by varying the ion fluence. Contact angle measurement of un-irradiated and irradiated mica surface shows a certain change from hydrophilicity to hydrophobicity. The physicochemical changes of mica surface due to Ar+ and N+ ion bombardment have been discussed.

On Both Spatial And Velocity Distribution Of Sputtered Particles In Magnetron Discharge

NASA Astrophysics Data System (ADS)

Vitelaru, C.; Pohoata, V.; Tiron, V.; Costin, C.; Popa, G.

2012-12-01

The kinetics of the sputtered atoms from the metallic target as well as the time-space distribution of the argon metastable atoms have been investigated for DC and high power pulse magnetron discharge by means of Tunable Diode - Laser Absorption Spectroscopy (TD-LAS) and Tunable Diode - Laser Induced Fluorescence (TD-LIF). The discharge was operated in argon (5-30 mTorr) with two different targets, tungsten and aluminum, for pulses of 1 to 20 μs, at frequencies of 0.2 to 1 kHz. Peak current intensity of ~100 A has been attained at cathode peak voltage of ~1 kV. The mean velocity distribution functions and particle fluxes of the sputtered metal atoms, in parallel and perpendicular direction to the target, have been obtained and compared for DC and pulse mode.

Sputtering and ion plating

NASA Technical Reports Server (NTRS)

1972-01-01

The proceedings of a conference on sputtering and ion plating are presented. Subjects discussed are: (1) concepts and applications of ion plating, (2) sputtering for deposition of solid film lubricants, (3) commercial ion plating equipment, (4) industrial potential for ion plating and sputtering, and (5) fundamentals of RF and DC sputtering.

Development of an inductively coupled impulse sputtering source for coating deposition

NASA Astrophysics Data System (ADS)

Loch, Daniel Alexander Llewellyn

In recent years, highly ionised pulsed plasma processes have had a great impact on improving the coating performance of various applications, such as for cutting tools and ITO coatings, allowing for a longer service life and improved defect densities. These improvements stem from the higher ionisation degree of the sputtered material in these processes and with this the possibility of controlling the flux of sputtered material, allowing the regulation of the hardness and density of coatings and the ability to sputter onto complex contoured substrates. The development of Inductively Coupled Impulse Sputtering (ICIS) is aimed at the potential of utilising the advantages of highly ionised plasma for the sputtering of ferromagnetic material. In traditional magnetron based sputter processes ferromagnetic materials would shunt the magnetic field of the magnetron, thus reducing the sputter yield and ionisation efficiency. By generating the plasma within a high power pulsed radio frequency (RF) driven coil in front of the cathode, it is possible to remove the need for a magnetron by applying a high voltage pulsed direct current to the cathode attracting argon ions from the plasma to initiate sputtering. This is the first time that ICIS technology has been deployed in a sputter coating system. To study the characteristics of ICIS, current and voltage waveforms have been measured to examine the effect of increasing RF-power. Plasma analysis has been conducted by optical emission spectroscopy to investigate the excitation mechanisms and the emission intensity. These are correlated to the set RF-power by modelling assumptions based on electron collisions. Mass spectroscopy is used to measure the plasma potential and ion energy distribution function. Pure copper, titanium and nickel coatings have been deposited on silicon with high aspect ratio via to measure the deposition rate and characterise the microstructure. For titanium and nickel the emission modelling results are in good agreement with the model expectations showing that electron collisions are the main excitation mechanism. The plasma potential was measured as 20 eV, this is an ideal level for good adatom mobility with reduced lattice defects. All surfaces in the via were coated, perpendicular column growth on the sidewalls indicates a predominantly ionised metal flux to the substrate and the deposition rates agree with the literature value of the sputter yield of the materials. The results of the studies show that ICIS is a viable process for the deposition of magnetic coatings with high ionisation in the plasma.

Nitriding of titanium and titanium: 8 percent aluminum, 1 percent molybdenum, 1 percent vanadium alloy with an ion-beam source

NASA Technical Reports Server (NTRS)

Gill, A.

1983-01-01

Titanium and Ti-8Al-1Mo-1V alloy were nitrided with an ion-beam source of nitrogen or argon and nitrogen at a total pressure of 2 x 10 to the minus 4th power to 10 x 10 to the minus 4th power torr. The treated surface was characterized by surface profilometry, X-ray diffractometry, Auger electron spectroscopy and microhardness measurements. The tetragonal Ti2N phase formed in pure titanium and Ti-8Al-1Mo-1V alloy with traces of AlN in the alloy. Two opposite processes competed during the ion-beam-nitriding process: (1) formation of nitrides in the surface layer and (2) sputtering of the nitrided layers by the ion beam. The highest surface hardnesses, about 500 kg/sq mm in titanium and 800 kg/sq mm in Ti-8Al-1Mo-1V, were obtained by ion nitriding with an ion beam of pure nitrogen at 4.2 x 10 to the minus 4th power torr at a beam voltage of 1000 V.

Studies on ion scattering and sputtering processes relevant to ion beam sputter deposition of multicomponent thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auciello, O.; Ameen, M.S.; Kingon, A.I.

1989-01-01

Results from computer simulation and experiments on ion scattering and sputtering processes in ion beam sputter deposition of high Tc superconducting and ferroelectric thin films are presented. It is demonstrated that scattering of neutralized ions from the targets can result in undesirable erosion of, and inert gas incorporation in, the growing films, depending on the ion/target atom ass ratio and ion beam angle of incidence/target/substrate geometry. The studies indicate that sputtering Kr{sup +} or Xe{sup +} ions is preferable to the most commonly used Ar{sup +} ions, since the undesirable phenomena mentioned above are minimized for the first two ions.more » These results are used to determine optimum sputter deposition geometry and ion beam parameters for growing multicomponent oxide thin films by ion beam sputter-deposition. 10 refs., 5 figs.« less

Nanoscale Investigation of Grain Growth in RF-Sputtered Indium Tin Oxide Thin Films by Scanning Probe Microscopy

NASA Astrophysics Data System (ADS)

Lamsal, B. S.; Dubey, M.; Swaminathan, V.; Huh, Y.; Galipeau, D.; Qiao, Q.; Fan, Q. H.

2014-11-01

This work studied the electronic characteristics of the grains and grain boundaries of indium tin oxide (ITO) thin films using electrostatic and Kelvin probe force microscopy. Two types of ITO films were compared, deposited using radiofrequency magnetron sputtering in pure argon or 99% argon + 1% oxygen, respectively. The average grain size and surface roughness increased with substrate temperature for the films deposited in pure argon. With the addition of 1% oxygen, the increase in the grain size was inhibited above 150°C, which was suggested to be due to passivation of the grains by the excess oxygen. Electrostatic force microscopy and Kelvin probe force microscopy (KPFM) images confirmed that the grain growth was defect mediated and occurred at defective interfaces at high temperatures. Films deposited at room temperature with 1% oxygen showed crystalline nature, while films deposited with pure argon at room temperature were amorphous as observed from KPFM images. The potential drop across the grain and grain boundary was determined by taking surface potential line profiles to evaluate the electronic properties.

Effect of dry air on interface smoothening in reactive sputter deposited Co/Ti multilayer

NASA Astrophysics Data System (ADS)

Biswas, A.; Porwal, A.; Bhattacharya, Debarati; Prajapat, C. L.; Ghosh, Arnab; Nand, Mangla; Nayak, C.; Rai, S.; Jha, S. N.; Singh, M. R.; Bhattacharyya, D.; Basu, S.; Sahoo, N. K.

2017-09-01

Top surface roughness and interface roughness are one of the key elements which determine the performance of X-ray and neutron thin film multilayer devices. It has been observed that by mixing air with argon in sputtering ambience during deposition of Co layers, polarized neutron reflectivity (PNR) of Co/Ti supermirror polarizers can be improved substantially. Cross-sectional HRTEM measurement reveals that sharper interfaces in the supermirror can be achieved in case of deposition of the multilayer under mixed ambience of argon and air. In order to investigate this interface modification mechanism further, in this communication two sets of tri-layer Co/Ti/Co samples and 20-layer Co/Ti periodic multilayer samples have been prepared; in one set all the layers are deposited only under argon ambience and in the other set, Co layers are deposited under a mixed ambience of argon and air. These samples have been characterized by measuring specular and non-specular X-ray reflectivities (GIXR) with X-rays of 1.54 Å wavelength and polarized neutron reflectivity (PNR) with neutron of 2.5 Å wavelength at grazing angle of incidence. It has been observed that the X-ray and neutron specular reflectivities at Bragg peaks of 20 layer periodic multilayer increase when Co layers are deposited under mixed ambience of argon and air. The detail information regarding the effect of air on the interfaces and magnetic properties has been obtained by fitting the measured spectra. The above information has subsequently been supplemented by XRD and magnetic measurements on the samples. XPS and XANES measurements have also been carried out to investigate whether cobalt oxide or cobalt nitride layers are being formed due to use of air in sputtering ambience.

Ion beam sputter etching and deposition of fluoropolymers

NASA Technical Reports Server (NTRS)

Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.

1978-01-01

Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanism and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

Influence of argon pressure and current density on substrate temperature during magnetron sputtering of hot titanium target

NASA Astrophysics Data System (ADS)

Komlev, Anton A.; Minzhulina, Ekaterina A.; Smirnov, Vladislav V.; Shapovalov, Viktor I.

2018-01-01

The paper describes physical characteristics of the hot target sputtering process, which have not been known before. To switch a magnetron over to the hot target regime, a titanium disk of 1 mm thick with a 1-mm-gap was attached on a 4-mm-thick copper plate cooled by running water. A thermocouple sensor was used to investigate the thermal processes occurring in substrates. The study was performed at the discharge current density of 20-40 mA/cm2 and argon pressure of 3-7 mTorr. The accuracy of temperature measurement appeared to be within ± 5%, due the application of a chromel-copel thermocouple. The study reveals that under these conditions the heating curves have the inflection points positioned proportionally to the discharge current density and argon pressure on a time axis. The inflection point appears in the kinetic curves due to the finite value of the target heating time constant. The study shows that the substrate fixed temperature and substrate heating time constant depend on the argon pressure and relate to the current density by the polynomials of the first and second degrees, respectively. The influence of a target on the substrate heating kinetics is considered in an analytical description by the introduction of a multiplier in the form of an exponential function of time. The results of the research make a novel contribution to the field of the sputtering process.

Effect of sputtering parameters on optical and electrical properties of ITO films on PET substrates

NASA Astrophysics Data System (ADS)

Tseng, Kun-San; Lo, Yu-Lung

2013-11-01

The optical and electrical properties of indium tin oxide (ITO) thin films deposited on flexible polyethylene terephthalate (PET) substrates using a DC magnetron sputtering technique are investigated as a function of the deposition time, the argon flow rate and the target-substrate distance. It is found that all of the ITO films contain a high fraction of amorphous phase. The volume fraction of crystallite precipitates in the amorphous host increases with an increasing deposition time or a reducing argon flow rate. The deposition time and argon flow rate have higher effects on the optical transparency of the ITO films than the target-substrate distance has. Increasing film thickness is not the only reason for the transmittance reduced. It is found that an increase of the extinction coefficient by increasing deposition time or an increase of the refractive index by decreasing argon flow rate also reduces the transmittance of thin film. For a constant deposition time, the resistivity of the ITO films reduces with a reducing argon flow rate or a reducing target-substrate distance. For a constant argon flow rate, a critical value of the deposition time exists at which both the resistivity and the effect of the target-substrate distance are minimized. Finally, it is concluded that the film resistivity has low sensitivity to the target-substrate distance if the best deposition conditions which mostly attain the lowest resistivity are matched.

Nickel nanowires mesh fabricated by ion beam irradiation-induced nanoscale welding for transparent conducting electrodes

NASA Astrophysics Data System (ADS)

Honey, S.; Ahmad, I.; Madhuku, M.; Naseem, S.; Maaza, M.; Kennedy, J. V.

2017-07-01

In this report, random nickel nanowires (Ni-NWs) meshes are fabricated by ions beam irradiation-induced nanoscale welding of NWs on intersecting positions. Ni-NWs are exposed to beam of 50 KeV Argon (Ar+) ions at various fluencies in the range ~1015 ions cm-2 to 1016 ions cm-2 at room temperature. Ni-NWs are welded due to accumulation of Ar+ ions beam irradiation-induced sputtered atoms on crossing positions. Ar+ ions irradiated Ni-NWs meshes are optically transparent and optical transparency is enhanced with increase in beam fluence of Ar+ ions. Ar+ ions beam irradiation-induced welded and optically transparent mesh is then exposed to 2.75 MeV hydrogen (H+) ions at fluencies 1  ×  1015 ions cm-2, 3  ×  1015 ions cm-2 and 1  ×  1016 ions cm-2 at room temperature. MeV H+ ions irradiation-induced local heat cause melting and fusion of NWs on intersecting points and eventually lead to reduce contact resistance between Ni-NWs. Electrical conductivity is enhanced with increase in beam fluence of H+ ions. These welded highly transparent and electrically conductive Ni-NWs meshes can be employed as transparent conducting electrodes in optoelectronic devices.

Molecular Depth Profiling of Sucrose Films: A Comparative Study of C₆₀n⁺ Ions and Traditional Cs⁺ and O₂⁺ Ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Zihua; Nachimuthu, Ponnusamy; Lea, Alan S.

2009-10-15

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth profiling of sucrose thin films were investigated using 10 keV C60+, 20 keV C602+, 30 keV C603+, 250 eV, 500 eV and 1000 eV Cs+ and O2+ as sputtering ions. With C60n+ ions, the molecular ion signal initially decreases, and reaches a steady-state that is about 38-51% of its original intensity, depending on the energy of the C60n+ ions. On the contrary, with Cs+ and O2+ sputtering, molecular ion signals decrease quickly to the noise level, even using low energy (250 eV) sputtering ions. In addition, the sucrose/Si interface by C60+ sputtering ismore » much narrower than that of Cs+ and O2+ sputtering. To understand the mechanisms of sputtering-induced damage by these ions, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize the bottoms of these sputter craters. XPS data show very little chemical change in the C60+ sputter crater, while considerable amorphous carbon was found in the O2+ and Cs+ sputter craters, indicating extensive decomposition of the sucrose molecules. AFM images show a very flat bottom in the C60+ sputter crater, while the Cs+ and O2+ sputter crater bottoms are significantly rougher than that of the C60+ sputter crater. Based on above data, we developed a simple model to explain different damage mechanisms during sputtering process.« less

Ion beam sputtering of Ag - Angular and energetic distributions of sputtered and scattered particles

NASA Astrophysics Data System (ADS)

Feder, René; Bundesmann, Carsten; Neumann, Horst; Rauschenbach, Bernd

2013-12-01

Ion beam sputter deposition (IBD) provides intrinsic features which influence the properties of the growing film, because ion properties and geometrical process conditions generate different energy and spatial distribution of the sputtered and scattered particles. A vacuum deposition chamber is set up to measure the energy and spatial distribution of secondary particles produced by ion beam sputtering of different target materials under variation of geometrical parameters (incidence angle of primary ions and emission angle of secondary particles) and of primary ion beam parameters (ion species and energies).

Analysis of surface sputtering on a quantum statistical basis

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.

1975-01-01

Surface sputtering is explained theoretically by means of a 3-body sputtering mechanism involving the ion and two surface atoms of the solid. By means of quantum-statistical mechanics, a formula for the sputtering ratio S(E) is derived from first principles. The theoretical sputtering rate S(E) was found experimentally to be proportional to the square of the difference between incident ion energy and the threshold energy for sputtering of surface atoms at low ion energies. Extrapolation of the theoretical sputtering formula to larger ion energies indicates that S(E) reaches a saturation value and finally decreases at high ion energies. The theoretical sputtering ratios S(E) for wolfram, tantalum, and molybdenum are compared with the corresponding experimental sputtering curves in the low energy region from threshold sputtering energy to 120 eV above the respective threshold energy. Theory and experiment are shown to be in good agreement.

Influence of Cu, Au and Ag on structural and surface properties of bioactive coatings based on titanium.

PubMed

Wojcieszak, D; Mazur, M; Kalisz, M; Grobelny, M

2017-02-01

In this work influence of copper, silver and gold additives on structural and surface properties of biologically active thin films based on titanium have been described. Coatings were prepared by magnetron sputtering method. During each process metallic discs (targets) - Ti and the additive (Cu, Ag or Au) were co-sputtered in argon atmosphere. Structural investigation of as-deposited coatings was performed with the aid of XRD and SEM/EDS method. It was found that all prepared thin films were homogenous. Addition of Cu, Ag and Au resulted in nanocrystalline structure. Moreover, influence of these additives on hardness and antibacterial activity of titanium coatings was also studied. Ti-Cu, Ti-Ag and Ti-Au films had lower hardness as-compared to Ti. According to AAS results the difference of their activity was related to the ion migration process. It was found that Ti-Ag and Ti-Au coatings had biocidal effect related to direct contact of their surface with microorganisms. In the case of Ti-Cu antimicrobial activity had direct and indirect nature due to efficient ion migration process from the film surface to the surrounding environment. Functional features of coatings such as wettability and corrosion resistance were also examined and included in the comprehensive analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

X-ray photoelectron spectroscopic study of surface chemistry of dibenzyl-disulfide on steel under mild and severe wear conditions

NASA Technical Reports Server (NTRS)

Wheeler, D. R.

1977-01-01

Wear tests were performed on 304 stainless steel lubricated with pure mineral oil with and without dibenzyl-disulfide. Both mild and severe wear were observed. The type of wear was distinguished by a marked change in wear rate, friction coefficient, and wear scar appearance. The chemical composition of the wear scar surface was examined with X-ray photoelectron spectroscopy in conjunction with argon ion sputter etching. In severe wear scars, a sulfide was formed at the expense of the normal oxide layer. In mild wear scars, there were only superficial sulfur compounds, but there was a substantial increase in the oxide thickness.

As-Received, Ozone Cleaned and Ar+ Sputtered Surfaces of Hafnium Oxide Grown by Atomic Layer Deposition and Studied by XPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engelhard, Mark H.; Herman, Jacob A.; Wallace, Robert

2012-06-27

In this study, X-ray photoelectron spectroscopy (XPS) characterization was performed on 47 nm thick hafnium oxide (HfO{sub 2}) films grown by atomic layer deposition using TEMA-Hf/H{sub 2}O at 250 C substrate temperature. HfO{sub 2} is currently being studied as a possible replacement for Silicon Oxide (SiO{sub 2}) as a gate dielectric in electronics transistors. XPS spectra were collected on a Physical Electronics Quantum 2000 Scanning ESCA Microprobe using a monochromatic Al K{sub a} X-ray (1486.7 eV) excitation source. The sample was analyzed under the following conditions: as received, after UV irradiation for five minutes, and after sputter cleaning with 2more » kV Ar{sup +} ions for 180 seconds. Survey scans showed carbon, oxygen, and hafnium as the major species in the film, while the only minor species of argon and carbide was detected after sputtering. Adventitious carbon initially composed approximately 18.6 AT% of the surface, but after UV cleaning it was reduced to 2.4 AT%. This demonstrated that that the majority of carbon was due to adventitious carbon. However, after 2 kV Ar{sup +} sputtering there was still only trace amounts of carbon at {approx}1 AT%, Some of this trace carbon is now in the form of a carbide due to the interaction with Ar{sup +} used for sputter cleaning. Furthermore, the stoiciometric ratio of oxygen and hafnium is consistent with a high quality HfO{sub 2} film.« less

Structural and emission characteristics of ion-irradiated Reticulated Vitreous Carbon

NASA Astrophysics Data System (ADS)

Chacon, Judith Rebecca

Cathodes formed from Reticulated Vitreous Carbon (RVC) were treated under varying conditions of Argon-ion beam current, beam voltage and irradiation duration. Surface structures, such as balls, cones, nanowires, and nanowhiskers were formed in the RVC network through a series of ion-impact sputtering and self-diffusion reactions. Raman shifts to the D and E2g' peak suggest C=C bonding within the original RVC structure was converted to the lesser-bound C-C bonding structure. Cathodes demonstrating the most stable electronic configuration exhibited significant vertical growth to graphitic domains as determined by calculations based on XRD measurements. Carbon nanotubes at the surface were observed at the surface through micro-Raman techniques. The surface structures formed by argon-bombardment, are responsible for cathodes exhibiting lower field-emission extraction fields. The electric field required for the onset of electron emission was measured to change from 6.03 V/micron in non-irradiated RVC to 1.62V/micron for RVC irradiated for 15 minutes at a beam voltage of 1200V and beam current of 200mA (ion-beam current density 2.24mA/cm2). Treated surfaces were also responsible for increased stability in emission over time. For untreated RVC, the field required for emission dropped 25% over a 48 hour training period, whilst modestly treated RVC (15min, 1200V, 100mA, or 1.52mA/cm2) rose as little as 3%. Field-emissive RVC, is an inexpensively produced, mechanically robust cathode with potential applications in lighting, displays and microwave sources.

Kinetics of carbide formation in the molybdenum-tungsten coatings used in the ITER-like Wall

NASA Astrophysics Data System (ADS)

Maier, H.; Rasinski, M.; von Toussaint, U.; Greuner, H.; Böswirth, B.; Balden, M.; Elgeti, S.; Ruset, C.; Matthews, G. F.

2016-02-01

The kinetics of tungsten carbide formation was investigated for tungsten coatings on carbon fibre composite with a molybdenum interlayer as they are used in the ITER-like Wall in JET. The coatings were produced by combined magnetron sputtering and ion implantation. The investigation was performed by preparing focused ion beam cross sections from samples after heat treatment in argon atmosphere. Baking of the samples was done at temperatures of 1100 °C, 1200 °C, and 1350 °C for hold times between 30 min and 20 h. It was found that the data can be well described by a diffusional random walk with a thermally activated diffusion process. The activation energy was determined to be (3.34 ± 0.11) eV. Predictions for the isothermal lifetime of this coating system were computed from this information.

First measurements of the temporal evolution of the plasma density in HiPIMS discharges using THz time domain spectroscopy

NASA Astrophysics Data System (ADS)

Meier, Steffen M.; Hecimovic, Ante; Tsankov, Tsanko V.; Luggenhölscher, Dirk; Czarnetzki, Uwe

2018-03-01

In this paper, the novel technique of THz time domain spectroscopy has been applied to obtain time-resolved measurements of the plasma density in the active zone of a HiPIMS discharge with a titanium target. The obtained peak values are in the range of 1012-1013 cm-3 for discharge current densities of 1-4 A cm-2 at 0.5 and 2 Pa argon pressure. The measured densities show good correlation with the discharge current and voltage and the intensity of various atomic and ionic lines. The well known phases of the discharge have been identified and related to the variation of the electron density. The measurement results show that the plasma density remains nearly constant during the runaway/self-sputtering phase. Based on that, it is conjectured that singly charged titanium ions are the dominant ion species during this phase.

Kinetic and Potential Sputtering of Lunar Regolith: Contribution of Solar-Wind Heavy Ions

NASA Technical Reports Server (NTRS)

Meyer, F. W.; Harris, P. R.; Meyer, H. M., III; Hijiazi, H.; Barghouty, A. F.

2013-01-01

Sputtering of lunar regolith by protons as well as solar-wind heavy ions is considered. From preliminary measurements of H+, Ar+1, Ar+6 and Ar+9 ion sputtering of JSC-1A AGGL lunar regolith simulant at solar wind velocities, and TRIM simulations of kinetic sputtering yields, the relative contributions of kinetic and potential sputtering contributions are estimated. An 80-fold enhancement of oxygen sputtering by Ar+ over same-velocity H+, and an additional x2 increase for Ar+9 over same-velocity Ar+ was measured. This enhancement persisted to the maximum fluences investigated is approximately 1016/cm (exp2). Modeling studies including the enhanced oxygen ejection by potential sputtering due to the minority heavy ion multicharged ion solar wind component, and the kinetic sputtering contribution of all solar wind constituents, as determined from TRIM sputtering simulations, indicate an overall 35% reduction of near-surface oxygen abundance. XPS analyses of simulant samples exposed to singly and multicharged Ar ions show the characteristic signature of reduced (metallic) Fe, consistent with the preferential ejection of oxygen atoms that can occur in potential sputtering of some metal oxides.

Installation of hybrid ion source on the 1-MV LLNL BioAMS spectrometer

PubMed Central

Ognibene, T. J.; Salazar, G. A.

2012-01-01

A second ion source was recently installed onto the LLNL 1-MV AMS spectrometer, which is dedicated to the quantification of 14C and 3H within biochemical samples. This source is unique among the other LLNL cesium sputter ion sources in that it can ionize both gaseous and solid samples. Also, the injection beam line has been designed to directly measure 14C/12C isotope ratios without the need for electrostatic bouncing. Preliminary tests show that this source can ionize transient CO2 gas pulses containing less than 1 ug carbon with approximately 1.5% efficiency. We demonstrate that the measured 14C/12C isotope ratio is largely unaffected by small drifts in the argon stripper gas density. We also determine that a tandem accelerating voltage of 670 kV enables the highest 14C transmission through the system. Finally, we describe a series of performance tests using solid graphite targets spanning nearly 3 orders in magnitude dynamic range and compare the results to our other ion source. PMID:23467295

Simultaneous ion sputter polishing and deposition

NASA Technical Reports Server (NTRS)

Rutledge, S.; Banks, B.; Brdar, M.

1981-01-01

Results of experiments to study ion beam sputter polishing in conjunction with simultaneous deposition as a mean of polishing copper surfaces are presented. Two types of simultaneous ion sputter polishing and deposition were used in these experiments. The first type utilized sputter polishing simultaneous with vapor deposition, and the second type utilized sputter polishing simultaneous with sputter deposition. The etch and deposition rates of both techniques were studied, as well as the surface morphology and surface roughness.

Influence of in-situ ion-beam sputter cleaning on the conditioning effect of vacuum gaps

NASA Astrophysics Data System (ADS)

Kobayashi, Shinichi; Kojima, Hiroyuki; Saito, Yoshio

1994-05-01

An ion beam sputtering technique was used to clean the electrode surfaces of vacuum gaps. Ions of the sputtering gas were irradiated by means of an ion gun in a vacuum chamber attached to a breakdown measurement chamber. By providing in situ ion-beam sputter cleaning, this system makes it possible to make measurements free from contamination due to exposure to the air. The sputtering gas was He or Ar, and the electrodes were made of oxygen-free copper (purity more than 99.96%). An impulse voltage with the wave form of 64/700 microsecond(s) was applied to the test gap, and the pressure in the breakdown measurement chamber at the beginning of breakdown tests was 1.3 X 10-8 Pa. These experiments showed that ion-beam sputter cleaning results in higher breakdown fields after a repetitive breakdown conditioning procedure, and that He is more effective in improving hold- off voltages after the conditioning (under the same ion current density, the breakdown field was 300 MV/m for He sputtering and 200 MV/m for Ar sputtering). The breakdown fields at the first voltage application after the sputtering cleaning, on the other hand, were not improved.

Development of long-lived thick carbon stripper foils for high energy heavy ion accelerators by a heavy ion beam sputtering method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muto, Hideshi; Ohshiro, Yukimitsu; Kawasaki, Katsunori

2013-04-19

In the past decade, we have developed extremely long-lived carbon stripper foils of 1-50 {mu}g/cm{sup 2} thickness prepared by a heavy ion beam sputtering method. These foils were mainly used for low energy heavy ion beams. Recently, high energy negative Hydrogen and heavy ion accelerators have started to use carbon stripper foils of over 100 {mu}g/cm{sup 2} in thickness. However, the heavy ion beam sputtering method was unsuccessful in production of foils thicker than about 50 {mu}g/cm{sup 2} because of the collapse of carbon particle build-up from substrates during the sputtering process. The reproduction probability of the foils was lessmore » than 25%, and most of them had surface defects. However, these defects were successfully eliminated by introducing higher beam energies of sputtering ions and a substrate heater during the sputtering process. In this report we describe a highly reproducible method for making thick carbon stripper foils by a heavy ion beam sputtering with a Krypton ion beam.« less

The effect of oxidant on resputtering of Bi from Bi-Sr-Ca-Cu-O films

NASA Astrophysics Data System (ADS)

Grace, J. M.; McDonald, D. B.; Reiten, M. T.; Olson, J.; Kampwirth, R. T.; Gray, K. E.

1991-09-01

The type and partial pressure of oxidant mixed with argon can affect the selective resputtering of Bi in composite-target, magnetron-sputtered Bi-Sr-Ca-Cu-O films. Comparative studies using oxygen and ozone show that ozone is a more potent oxidant, as well as a more potent source of resputterers, than is oxygen. Severe resputtering from ozone is significantly reduced by a -40 V potential on the sample block. We suggest that oxygen causes resputtering by forming O2(+)p , which interacts with the target to produce energetic O(-). In contrast, ozone may form lower-energy O(-) by electron impact in the dark space. Negative oxygen ions from the target itself may be responsible for a background resputtering effect. Our results and those found for Y-Ba-Cu-O by others are comparable. Bi in Bi-Sr-Ca-Cu-O behaves as Ba in Y-Ba-Cu-O, with regard to selective resputtering; furthermore, the response of Sr, Ca, and Cu to oxygen in sputtered Bi-Sr-Ca-Cu-O is similar to what is observed for Cu in Y-Ba-Cu-O.

ARCS 3 ionospheric artificial argon ion beam injections - Waves near the heavy ion gyrofrequencies

NASA Technical Reports Server (NTRS)

Erlandson, R. E.; Cahill, L. J., Jr.; Kaufmann, R. L.; Arnoldy, R. L.; Pollock, C. J.

1989-01-01

Low-frequency electric field data below the proton gyrofrequency are presented for the duration of the argon ion beam experiment conducted as part of the Argon Release for Controlled Studies (ARCS) program. An argon ion beam was injected from the subpayload antiparallel or perpendicular to the magnetic field at altitudes from 250 to 405 km. During the injections, the wave spectra were broadband near the subpayload and narrow-band near heavy ion gyrofrequencies at perpendicular separation distances between 42 and 254 m. It is suggested that the narrow-band waves are associated with both the perpendicular argon ion beam and an unexpected flux of low-energy ions which peaked in energy near 15 eV and pitch angle near 90 deg with respect to the magnetic field.

Gettering of Residual Impurities by Ion Implantation Damage in Poly-AlN UV Diode Detectors

NASA Astrophysics Data System (ADS)

Khan, A. H.; Stacy, T.; Meese, J. M.

1996-03-01

UV diode detectors have been fabricated from oriented polycrystalline AlN grown on (111) n-type 3-15Ω-cm Si substrates by CVD using AlCl3 and ammonia with a hydrogen carrier gas at 760-800C, 40-45 torr and gas flow rates of 350, 120, and 120 sccm for hydrogen, ammonia and hydrogen over heated AlCl_3. Half of the AlN film of thickness 1.5-2.0 microns was masked off prior to ion implantation. Samples were ion-implanted at 5 kV with methane, nitrogen and argon to a dose of 5-6 x 10^18 ions/cm^2. The AlN was contacted with sputtered Au while the Si was contacted with evaporated Al. No annealing was performed. Rectification was obtained as a result of radiation damage in the AlN. SIMs analysis showed a reduction of oxygen, hydrogen, chlorine and carbon by several orders of magnitude and to a depth of several microns in the ion implanted samples compared to the masked samples. The quantum efficiency was 16nm uncorrected for reflection from the AlN and thin metal contact.

Studies on the Extraction Region of the Type VI RF Driven H- Ion Source

NASA Astrophysics Data System (ADS)

McNeely, P.; Bandyopadhyay, M.; Franzen, P.; Heinemann, B.; Hu, C.; Kraus, W.; Riedl, R.; Speth, E.; Wilhelm, R.

2002-11-01

IPP Garching has spent several years developing a RF driven H- ion source intended to be an alternative to the current ITER (International Thermonuclear Experimental Reactor) reference design ion source. A RF driven source offers a number of advantages to ITER in terms of reduced costs and maintenance requirements. Although the RF driven ion source has shown itself to be competitive with a standard arc filament ion source for positive ions many questions still remain on the physics behind the production of the H- ion beam extracted from the source. With the improvements that have been implemented to the BATMAN (Bavarian Test Machine for Negative Ions) facility over the last two years it is now possible to study both the extracted ion beam and the plasma in the vicinity of the extraction grid in greater detail. This paper will show the effect of changing the extraction and acceleration voltage on both the current and shape of the beam as measured on the calorimeter some 1.5 m downstream from the source. The extraction voltage required to operate in the plasma limit is 3 kV. The perveance optimum for the extraction system was determined to be 2.2 x 10-6 A/V3/2 and occurs at 2.7 kV extraction voltage. The horizontal and vertical beam half widths vary as a function of the extracted ion current and the horizontal half width is generally smaller than the vertical. The effect of reducing the co-extracted electron current via plasma grid biasing on the H- current extractable and the beam profile from the source is shown. It is possible in the case of a silver contaminated plasma to reduce the co-extracted electron current to 20% of the initial value by applying a bias of 12 V. In the case where argon is present in the plasma, biasing is observed to have minimal effect on the beam half width but in a pure hydrogen plasma the beam half width increases as the bias voltage increases. New Langmuir probe studies that have been carried out parallel to the plasma grid (in the vicinity of the peak of the external magnetic filter field) and changes to source parameters as a function of power, and argon addition are reported. The behaviour of the electron density is different when the plasma is argon seeded showing a strong increase with RF power. The plasma potential is decreased by 2 V when argon is added to the plasma. The effect of the presence of unwanted silver sputtered from the Faraday screen by Ar+ ions on both the source performance and the plasma parameters is also presented. The silver dramatically downgraded source performance in terms of current density and produced an early saturation of current with applied RF power. Recently, collaboration was begun with the Technical University of Augsburg to perform spectroscopic measurements on the Type VI ion source. The final results of this analysis are not yet ready but some interesting initial observations on the gas temperature, disassociation degree and impurity ions will be presented.

The Neutral Mass Spectrometer on the Lunar Atmosphere and Dust Environment Explorer Mission

NASA Technical Reports Server (NTRS)

Mahaffy, Paul R.; Hodges, R. Richard; Benna, Mehdi; King, Todd; Arvey, Robert; Barciniak, Michael; Bendt, Mirl; Carigan, Daniel; Errigo, Therese; Harpold, Daniel N.;

Low energy sputtering of cobalt by cesium ions

NASA Technical Reports Server (NTRS)

Handoo, A.; Ray, Pradosh K.

1989-01-01

An experimental facility to investigate low energy (less than 500 eV) sputtering of metal surfaces with ions produced by an ion gun is described. Results are reported on the sputtering yield of cobalt by cesium ions in the 100 to 500 eV energy range at a pressure of 1 times 10(exp -6) Torr. The target was electroplated on a copper substrate. The sputtered atoms were collected on a cobalt foil surrounding the target. Co-57 was used as a tracer to determine the sputtering yield.

Estimates of Sputter Yields of Solar-Wind Heavy Ions of Lunar Regolith Materials

NASA Technical Reports Server (NTRS)

Barghouty, Abdulmasser F.; Adams, James H., Jr.

2008-01-01

At energies of approximately 1 keV/amu, solar-wind protons and heavy ions interact with the lunar surface materials via a number of microscopic interactions that include sputtering. Solar-wind induced sputtering is a main mechanism by which the composition of the topmost layers of the lunar surface can change, dynamically and preferentially. This work concentrates on sputtering induced by solar-wind heavy ions. Sputtering associated with slow (speeds the electrons speed in its first Bohr orbit) and highly charged ions are known to include both kinetic and potential sputtering. Potential sputtering enjoys some unique characteristics that makes it of special interest to lunar science and exploration. Unlike the yield from kinetic sputtering where simulation and approximation schemes exist, the yield from potential sputtering is not as easy to estimate. This work will present a preliminary numerical scheme designed to estimate potential sputtering yields from reactions relevant to this aspect of solar-wind lunar-surface coupling.

Development of RF sputtered chromium oxide coating for wear application

NASA Technical Reports Server (NTRS)

Bhushan, B.

1979-01-01

The radio frequency sputtering technique was used to deposite a hard refractory, chromium oxide coating on an Inconel X-750 foil 0.1 mm thick. Optimized sputtering parameters for a smooth and adherent coating were found to be as follows: target-to-substrate spacing, 41.3 mm; argon pressure, 5-10 mTorr; total power to the sputtering module, 400 W (voltage at the target, 1600 V), and a water-cooled substrate. The coating on the annealed foil was more adherent than that on the heat-treated foil. Substrate biasing during the sputter deposition of Cr2O3 adversely affected adherence by removing naturally occurring interfacial oxide layers. The deposited coatings were amorphous and oxygen deficient. Since amorphous materials are extremely hard, the structure was considered to be desirable.

Thickness and surface roughness study of co-sputtered nanostructured alumina/tungsten (Al2O3/W) thin films

NASA Astrophysics Data System (ADS)

Naveen, A.; Krishnamurthy, L.; Shridhar, T. N.

2018-04-01

Tungsten (W) and Alumina (Al2O3) thin films have been developed using co-sputtering technique on SS304, Copper (Cu) and Glass slides using Direct Current magnetron sputtering (DC) and Radio Frequency (RF) magnetron sputtering methods respectively. Central Composite Design (CCD) method approach has been adopted to determine the number of experimental plans for deposition and DC power, RF power and Argon gas flow rate have been input parameters, each at 5 levels for development of thin films. In this research paper, study has been carried out determine the optimized condition of deposition parameters for thickness and surface roughness of the thin films. Thickness and average Surface roughness in terms of nanometer (nm) have been characterized by thickness profilometer and atomic force microscopy respectively. The maximum and minimum average thickness observed to be 445 nm and 130 respectively. The optimum deposition condition for W/Al2O3 thin film growth was determined to be at 1000 watts of DC power and 800 watts of RF power, 20 minutes of deposition time, and almost 300 Standard Cubic Centimeter(SCCM) of Argon gas flow. It was observed that average roughness difference found to be less than one nanometer on SS substrate and one nanometer on copper approximately.

Kinetic and potential sputtering of an anorthite-like glassy thin film

DOE PAGES

Hijazi, H.; Bannister, M. E.; Meyer, H. M.; ...

2017-07-28

In this paper, we present measurements of He + and He +2 ion-induced sputtering of an anorthite-like thin film at a fixed solar wind-relevant impact energy of ~0.5 keV/amu using a quartz crystal microbalance approach (QCM) for determination of total absolute sputtering yields. He +2 ions are the most abundant multicharged ions in the solar wind, and increased sputtering by these ions in comparison to equivelocity He + ions is expected to have the biggest effect on the overall sputtering efficiency of solar wind impact on the Moon. These measurements indicate an almost 70% increase of the sputtering yield formore » doubly charged incident He ions compared to that for same velocity He + impact (14.6 amu/ion for He +2 vs. 8.7 amu/ion for He+). Using a selective sputtering model, the new QCM results presented here, together with previously published results for Ar +q ions and SRIM results for the relevant kinetic-sputtering yields, the effect due to multicharged-solar-wind-ion impact on local near-surface modification of lunar anorthite-like soil is explored. It is shown that the multicharged-solar-wind component leads to a more pronounced and significant differentiation of depleted and enriched surface elements as well as a shortening of the timescale over which such surface-compositional modifications might occur in astrophysical settings. Additionally, to validate previous and future determinations of multicharged-ion-induced sputtering enhancement for those cases where the QCM approach cannot be used, relative quadrupole mass spectrometry (QMS)-based measurements are presented for the same anorthite-like thin film as were investigated by QCM, and their suitability and limitations for charge state-enhanced yield measurements are discussed.« less

Kinetic and potential sputtering of an anorthite-like glassy thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hijazi, H.; Bannister, M. E.; Meyer, H. M.

In this paper, we present measurements of He + and He +2 ion-induced sputtering of an anorthite-like thin film at a fixed solar wind-relevant impact energy of ~0.5 keV/amu using a quartz crystal microbalance approach (QCM) for determination of total absolute sputtering yields. He +2 ions are the most abundant multicharged ions in the solar wind, and increased sputtering by these ions in comparison to equivelocity He + ions is expected to have the biggest effect on the overall sputtering efficiency of solar wind impact on the Moon. These measurements indicate an almost 70% increase of the sputtering yield formore » doubly charged incident He ions compared to that for same velocity He + impact (14.6 amu/ion for He +2 vs. 8.7 amu/ion for He+). Using a selective sputtering model, the new QCM results presented here, together with previously published results for Ar +q ions and SRIM results for the relevant kinetic-sputtering yields, the effect due to multicharged-solar-wind-ion impact on local near-surface modification of lunar anorthite-like soil is explored. It is shown that the multicharged-solar-wind component leads to a more pronounced and significant differentiation of depleted and enriched surface elements as well as a shortening of the timescale over which such surface-compositional modifications might occur in astrophysical settings. Additionally, to validate previous and future determinations of multicharged-ion-induced sputtering enhancement for those cases where the QCM approach cannot be used, relative quadrupole mass spectrometry (QMS)-based measurements are presented for the same anorthite-like thin film as were investigated by QCM, and their suitability and limitations for charge state-enhanced yield measurements are discussed.« less

Kinetic and potential sputtering of an anorthite-like glassy thin film

NASA Astrophysics Data System (ADS)

Hijazi, H.; Bannister, M. E.; Meyer, H. M.; Rouleau, C. M.; Meyer, F. W.

2017-07-01

In this paper, we present measurements of He+ and He+2 ion-induced sputtering of an anorthite-like thin film at a fixed solar wind-relevant impact energy of 0.5 keV/amu using a quartz crystal microbalance approach (QCM) for determination of total absolute sputtering yields. He+2 ions are the most abundant multicharged ions in the solar wind, and increased sputtering by these ions in comparison to equivelocity He+ ions is expected to have the biggest effect on the overall sputtering efficiency of solar wind impact on the Moon. Our measurements indicate an almost 70% increase of the sputtering yield for doubly charged incident He ions compared to that for same velocity He+ impact (14.6 amu/ion for He+2 vs. 8.7 amu/ion for He+). Using a selective sputtering model, the new QCM results presented here, together with previously published results for Ar+q ions and SRIM results for the relevant kinetic-sputtering yields, the effect due to multicharged-solar-wind-ion impact on local near-surface modification of lunar anorthite-like soil is explored. It is shown that the multicharged-solar-wind component leads to a more pronounced and significant differentiation of depleted and enriched surface elements as well as a shortening of the timescale over which such surface-compositional modifications might occur in astrophysical settings. In addition, to validate previous and future determinations of multicharged-ion-induced sputtering enhancement for those cases where the QCM approach cannot be used, relative quadrupole mass spectrometry (QMS)-based measurements are presented for the same anorthite-like thin film as were investigated by QCM, and their suitability and limitations for charge state-enhanced yield measurements are discussed.

Ion beam sputter deposited zinc telluride films

NASA Technical Reports Server (NTRS)

Gulino, D. A.

1986-01-01

Zinc telluride is of interest as a potential electronic device material, particularly as one component in an amorphous superlattice, which is a new class of interesting and potentially useful materials. Some structural and electronic properties of ZnTe films deposited by argon ion beam sputter deposition are described. Films (up to 3000 angstroms thick) were deposited from a ZnTe target. A beam energy of 1000 eV and a current density of 4 mA/sq cm resulted in deposition rates of approximately 70 angstroms/min. The optical band gap was found to be approximately 1.1 eV, indicating an amorphous structure, as compared to a literature value of 2.26 eV for crystalline material. Intrinsic stress measurements showed a thickness dependence, varying from tensile for thicknesses below 850 angstroms to compressive for larger thicknesses. Room temperature conductivity measurement also showed a thickness dependence, with values ranging from 1.86 x 10 to the -6th/ohm cm for 300 angstrom film to 2.56 x 10 to the -1/ohm cm for a 2600 angstrom film. Measurement of the temperature dependence of the conductivity for these films showed complicated behavior which was thickness dependent. Thinner films showed at least two distinct temperature dependent conductivity mechanisms, as described by a Mott-type model. Thicker films showed only one principal conductivity mechanism, similar to what might be expected for a material with more crystalline character.

Ion beam sputter deposited zinc telluride films

NASA Technical Reports Server (NTRS)

Gulino, D. A.

1985-01-01

Zinc telluride is of interest as a potential electronic device material, particularly as one component in an amorphous superlattice, which is a new class of interesting and potentially useful materials. Some structural and electronic properties of ZnTe films deposited by argon ion beam sputter depoairion are described. Films (up to 3000 angstroms thick) were deposited from a ZnTe target. A beam energy of 1000 eV and a current density of 4 mA/sq. cm. resulted in deposition rates of approximately 70 angstroms/min. The optical band gap was found to be approximately 1.1 eV, indicating an amorphous structure, as compared to a literature value of 2.26 eV for crystalline material. Intrinsic stress measurements showed a thickness dependence, varying from tensile for thicknesses below 850 angstroms to compressive for larger thicknesses. Room temperature conductivity measurement also showed a thickness dependence, with values ranging from 1.86 x to to the -6/ohm. cm. for 300 angstrom film to 2.56 x 10 to the -1/ohm. cm. for a 2600 angstrom film. Measurement of the temperature dependence of the conductivity for these films showed complicated behavior which was thickness dependent. Thinner films showed at least two distinct temperature dependent conductivity mechanisms, as described by a Mott-type model. Thicker films showed only one principal conductivity mechanism, similar to what might be expected for a material with more crystalline character.

Monte Carlo simulations of nanoscale focused neon ion beam sputtering.

PubMed

Timilsina, Rajendra; Rack, Philip D

2013-12-13

A Monte Carlo simulation is developed to model the physical sputtering of aluminum and tungsten emulating nanoscale focused helium and neon ion beam etching from the gas field ion microscope. Neon beams with different beam energies (0.5-30 keV) and a constant beam diameter (Gaussian with full-width-at-half-maximum of 1 nm) were simulated to elucidate the nanostructure evolution during the physical sputtering of nanoscale high aspect ratio features. The aspect ratio and sputter yield vary with the ion species and beam energy for a constant beam diameter and are related to the distribution of the nuclear energy loss. Neon ions have a larger sputter yield than the helium ions due to their larger mass and consequently larger nuclear energy loss relative to helium. Quantitative information such as the sputtering yields, the energy-dependent aspect ratios and resolution-limiting effects are discussed.

Ion radiation albedo effect: influence of surface roughness on ion implantation and sputtering of materials

NASA Astrophysics Data System (ADS)

Li, Yonggang; Yang, Yang; Short, Michael P.; Ding, Zejun; Zeng, Zhi; Li, Ju

2017-01-01

In fusion devices, ion retention and sputtering of materials are major concerns in the selection of compatible plasma-facing materials (PFMs), especially in the context of their microstructural conditions and surface morphologies. We demonstrate how surface roughness changes ion implantation and sputtering of materials under energetic ion irradiation. Using a new, sophisticated 3D Monte Carlo (MC) code, IM3D, and a random rough surface model, ion implantation and the sputtering yields of tungsten (W) with a surface roughness varying between 0-2 µm have been studied for irradiation by 0.1-1 keV D+, He+ and Ar+ ions. It is found that both ion backscattering and sputtering yields decrease with increasing roughness; this is hereafter called the ion radiation albedo effect. This effect is mainly dominated by the direct, line-of-sight deposition of a fraction of emitted atoms onto neighboring asperities. Backscattering and sputtering increase with more oblique irradiation angles. We propose a simple analytical formula to relate rough-surface and smooth-surface results.

Note on the artefacts in SRIM simulation of sputtering

NASA Astrophysics Data System (ADS)

Shulga, V. I.

2018-05-01

The computer simulation program SRIM, unlike other well-known programs (MARLOWE, TRIM.SP, etc.), predicts non-zero values of the sputter yield at glancing ion bombardment of smooth amorphous targets and, for heavy ions, greatly underestimates the sputter yield at normal incidence. To understand the reasons for this, the sputtering of amorphous silicon bombarded with different ions was modeled here using the author's program OKSANA. Most simulations refer to 1 keV Xe ions, and angles of incidence cover range from 0 (normal incidence) to almost 90°. It has been shown that SRIM improperly simulates the initial stage of the sputtering process. Some other artefacts in SRIM calculations of sputtering are also revealed and discussed.

Low-Energy Sputtering Research

NASA Technical Reports Server (NTRS)

Ray, P. K.; Shutthanandan, V.

1999-01-01

An experimental study is described to measure low-energy (less than 600 eV) sputtering yields of molybdenum with xenon ions using Rutherford backscattering spectroscopy (RBS) and secondary neutral mass spectroscopy (SNMS). An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 (micro)A/sq cm. For RBS measurements, the sputtered material was collected on a thin aluminum strip which was mounted on a semi-circular collector plate. The target was bombarded with 200 and 500 eV xenon ions at normal incidence. The differential sputtering yields were measured using the RBS method with 1 MeV helium ions. The differential yields were fitted with a cosine fitting function and integrated with respect to the solid angle to provide the total sputtering yields. The sputtering yields obtained using the RBS method are in reasonable agreement with those measured by other researchers using different techniques. For the SNMS measurements, 150 to 600 eV xenon ions were used at 50deg angle of incidence. The SNMS spectra were converted to sputtering yields for perpendicular incidence by normalizing SNMS spectral data at 500 eV with the yield measured by Rutherford backscattering spectrometry. Sputtering yields as well as the shape of the yield-energy curve obtained in this manner are in reasonable agreement with those measured by other researchers using different techniques. Sputtering yields calculated by using two semi-spherical formulations agree reasonably well with measured data. The isotopic composition of secondary ions were measured by bombarding copper with xenon ions at energies ranging from 100 eV to 1.5 keV. The secondary ion flux was found to be enriched in heavy isotopes at low incident ion energies. The heavy isotope enrichment was observed to decrease with increasing impact energy. Beyond 700 eV, light isotopes were sputtered preferentially with the enrichment remaining nearly constant.

Observing Planets and Small Bodies in Sputtered High Energy Atom (SHEA) Fluxes

NASA Technical Reports Server (NTRS)

Milillo, A.; Orsini, S.; Hsieh, K. C.; Baragiola, R.; Fama, M.; Johnson, R.; Mura, A.; Plainaki, Ch.; Sarantos, M.; Cassidy, T. A.;

The structure of biocoats based on TiO2 doped with nitrogen study

NASA Astrophysics Data System (ADS)

Boytsova, E. L.; Leonova, L. A.; Pichugin, V. F.

2018-04-01

Nitrogen-doped titanium dioxide (N-TiO2) nanofilms were deposited by reactive magnetron sputtering under different bias voltage. The mode of sputtering influences to formation and properties of titanium films. X-ray diffraction (XRD) was used to study the phase transition and crystallinity of the nanofilms. A technique of layer-by-layer measurement of Raman scattering from nanostructured titanium dioxide films based on a preliminary sputtering of the films by argon beam under an angle of 45° and less has been developed. Experimentally confirmed low dissolution rate of the coating in NaCl saline (0.9%).

Sputtering Erosion in the Ion Thruster

NASA Technical Reports Server (NTRS)

Ray, Pradosh K.; Mantenieks, Maris A. (Technical Monitor)

2000-01-01

During the first phase of this research, the sputtering yields of molybdenum by low energy (100 eV and higher) xenon ions were measured by using the methods of secondary neutral mass spectrometry (SNMS) and Rutherford backscattering spectrometry (RBS). However, the measured sputtering yields were found to be far too low to explain the sputtering erosions observed in the long-duration tests of ion thrusters. The only difference between the sputtering yield measurement experiments and the ion thruster tests was that the later are conducted at high ion fluences. Hence, a study was initiated to investigate if any linkage exists between high ion fluence and an enhanced sputtering yield. The objective of this research is to gain an understanding of the causes of the discrepancies between the sputtering rates of molybdenum grids in an ion thruster and those measured from our experiments. We are developing a molecular dynamics simulation technique for studying low-energy xenon ion interactions with molybdenum. It is difficult to determine collision sequences analytically for primary ions below the 200 eV energy range where the ion energy is too low to be able to employ a random cascade model with confidence and it is too high to have to consider only single collision at or near the surface. At these low energies, the range of primary ions is about 1 to 2 nm from the surface and it takes less than 4 collisions on the average to get an ion to degrade to such an energy that it can no longer migrate. The fine details of atomic motion during the sputtering process are revealed through computer simulation schemes. By using an appropriate interatomic potential, the positions and velocities of the incident ion together with a sufficient number of target atoms are determined in small time steps. Hence, it allows one to study the evolution of damages in the target and its effect on the sputtering yield. We are at the preliminary stages of setting up the simulation program.

S180 cell growth on low ion energy plasma treated TiO 2 thin films

NASA Astrophysics Data System (ADS)

Dhayal, Marshal; Cho, Su-In; Moon, Jun Young; Cho, Su-Jin; Zykova, Anna

2008-03-01

X-ray photoelectron spectroscopy (XPS) was used to characterise the effects of low energy (<2 eV) argon ion plasma surface modification of TiO 2 thin films deposited by radio frequency (RF) magnetron sputter system. The low energy argon ion plasma surface modification of TiO 2 in a two-stage hybrid system had increased the proportion of surface states of TiO 2 as Ti 3+. The proportion of carbon atoms as alcohol/ether (C sbnd OX) was decreased with increase the RF power and carbon atoms as carbonyl (C dbnd O) functionality had increased for low RF power treatment. The proportion of C( dbnd O)OX functionality at the surface was decreased at low power and further increase in power has showed an increase in its relive proportion at the surface. The growth of S180 cells was observed and it seems that cells are uniformly spreads on tissue culture polystyrene surface and untreated TiO 2 surfaces whereas small-localised cell free area can be seen on plasma treated TiO 2 surfaces which may be due to decrease in C( dbnd O)OX, increase in C dbnd O and active sites at the surface. A relatively large variation in the surface functionalities with no change in the surface roughness was achieved by different RF plasma treatments of TiO 2 surface whereas no significant change in S180 cell growth with different plasma treatments. This may be because cell growth on TiO 2 was mainly influenced by nano-surface characteristics of oxide films rather than surface chemistry.

Deposition of PTFE thin films by ion beam sputtering and a study of the ion bombardment effect

NASA Astrophysics Data System (ADS)

He, J. L.; Li, W. Z.; Wang, L. D.; Wang, J.; Li, H. D.

1998-02-01

Ion beam sputtering technique was employed to prepare thin films of Polytetrafluroethylene (PTFE). Simultaneous ion beam bombardment during film growth was also conducted in order to study the bombardment effects. Infrared absorption (IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis was used to evaluate the material's integrity. It was found that PTFE thin films could be grown at room temperature by direct sputtering of a PTFE target. The film's composition and structure were shown to be dependent on the sputtering energy. Films deposited by single sputtering at higher energy (˜1500 eV) were structurally quite similar to the original PTFE material. Simultaneous ion beam bombarding during film growth caused defluorination and structural changes. Mechanism for sputtering deposition of such a polymeric material is also discussed.

High density circuit technology

NASA Technical Reports Server (NTRS)

Wade, T. E.

1979-01-01

Polyimide dielectric materials were acquired for comparative and evaluative studies in double layer metal processes. Preliminary experiments were performed. Also, the literature indicates that sputtered aluminum films may be successfully patterned using the left-off technique provided the substrate temperature remains low and the argon pressure in the chamber is relatively high at the time of sputtering. Vendors associated with dry processing equipment are identified. A literature search relative to future trends in VLSI fabrication techniques is described.

Cosine (Cobalt Silicide Growth Through Nitrogen-Induced Epitaxy) Process For Epitaxial Cobalt Silicide Formation For High Performance Sha

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Chong Wee; Shin, Chan Soo; Gall, Daniel

A method for forming an epitaxial cobalt silicide layer on a MOS device includes sputter depositing cobalt in an ambient to form a first layer of cobalt suicide on a gate and source/drain regions of the MOS device. Subsequently, cobalt is sputter deposited again in an ambient of argon to increase the thickness of the cobalt silicide layer to a second thickness.

Textured carbon surfaces on copper by sputtering

NASA Technical Reports Server (NTRS)

Curren, A. N. (Inventor); Jensen, K. A. (Inventor); Roman, R. F. (Inventor)

1986-01-01

A very thin layer of highly textured carbon is applied to a copper surface by a triode sputtering process. A carbon target and a copper substrate are simultaneously exposed to an argon plasma in a vacuum chamber. The resulting carbon surface is characterized by a dense, random array of needle like spires or peaks which extend perpendicularly from the copper surface. The coated copper is especially useful for electrode plates in multistage depressed collectors.

A Closer Look at Solar Wind Sputtering of Lunar Surface Materials

NASA Technical Reports Server (NTRS)

Barghouty, A. F.; Adams, J. H., Jr.; Meyer, F.; Mansur, L.; Reinhold, C.

2008-01-01

Solar-wind induced potential sputtering of the lunar surface may be a more efficient erosive mechanism than the "standard" kinetic (or physical) sputtering. This is partly based on new but limited laboratory measurements which show marked enhancements in the sputter yields of slow-moving, highly-charged ions impacting oxides. The enhancements seen in the laboratory can be orders of magnitude for some surfaces and highly charged incident ions, but seem to depend very sensitively on the properties of the impacted surface in addition to the fluence, energy and charge of the impacting ion. For oxides, potential sputtering yields are markedly enhanced and sputtered species, especially hydrogen and light ions, show marked dependence on both charge and dose.

Physical deoxygenation of graphene oxide paper surface and facile in situ synthesis of graphene based ZnO films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Jijun; Wang, Minqiang, E-mail: mqwang@mail.xjtu.edu.cn; Zhang, Xiangyu

2014-12-08

In-situ sputtering ZnO films on graphene oxide (GO) paper are used to fabricate graphene based ZnO films. Crystal structure and surface chemical states are investigated. Results indicated that GO paper can be effectively deoxygenated by in-situ sputtering ZnO on them without adding any reducing agent. Based on the principle of radio frequency magnetron sputtering, we propose that during magnetron sputtering process, plasma streams contain large numbers of electrons. These electrons not only collide with argon atoms to produce secondary electrons but also they are accelerated to bombard the substrates (GO paper) resulting in effective deoxygenation of oxygen-containing functional groups. In-situmore » sputtering ZnO films on GO paper provide an approach to design graphene-semiconductor nanocomposites.« less

A thermalized ion explosion model for high energy sputtering and track registration

NASA Technical Reports Server (NTRS)

Seiberling, L. E.; Griffith, J. E.; Tombrello, T. A.

1980-01-01

A velocity spectrum of neutral sputtered particles as well as a low resolution mass spectrum of sputtered molecular ions was measured for 4.74 MeV F-19(+2) incident of UF4. The velocity spectrum is dramatically different from spectra taken with low energy (keV) bombarding ions, and is shown to be consistent with a hot plasma of atoms in thermal equilibrium inside the target. A thermalized ion explosion model is proposed for high energy sputtering which is expected to describe track formation in dielectric materials. The model is shown to be consistent with the observed total sputtering yield and the dependence of the yield on the primary ionization rate of the incident ion.

Ion beam texturing

NASA Technical Reports Server (NTRS)

Hudson, W. R.

1976-01-01

A microscopic surface texture is created by sputter etching a surface while simultaneously sputter depositing a lower sputter yield material onto the surface. A xenon ion beam source has been used to perform this texturing process on samples as large as three centimeters in diameter. Ion beam textured surface structures have been characterized with SEM photomicrographs for a large number of materials including Cu, Al, Si, Ti, Ni, Fe, Stainless steel, Au, and Ag. Surfaces have been textured using a variety of low sputter yield materials - Ta, Mo, Nb, and Ti. The initial stages of the texture creation have been documented, and the technique of ion beam sputter removal of any remaining deposited material has been studied. A number of other texturing parameters have been studied such as the variation of the texture with ion beam power, surface temperature, and the rate of texture growth with sputter etching time.

Three-dimensional particle simulation of back-sputtered carbon in electric propulsion test facility

NASA Astrophysics Data System (ADS)

Zheng, Hongru; Cai, Guobiao; Liu, Lihui; Shang, Shengfei; He, Bijiao

2017-03-01

The back-sputtering deposition on thruster surface caused by ion bombardment on chamber wall material affects the performance of thrusters during the ground based electric propulsion endurance tests. In order to decrease the back-sputtering deposition, most of vacuum chambers applied in electric propulsion experiments are equipped with anti-sputtering targets. In this paper, a three-dimensional model of plume experimental system (PES) including double layer anti-sputtering target is established. Simulation cases are made to simulate the plasma environment and sputtering effects when an ion thruster is working. The particle in cell (PIC) method and direct simulation Monte Carlo (DSMC) method is used to calculate the velocity and position of particles. Yamamura's model is used to simulate the sputtering process. The distribution of sputtered anti-sputtering target material is presented. The results show that the double layer anti-sputtering target can significantly reduce the deposition on thruster surface. The back-sputtering deposition rates on thruster exit surface for different cases are compared. The chevrons on the secondary target are rearranged to improve its performance. The position of secondary target has relation with the ion beam divergence angle, and the radius of the vacuum chamber. The back-sputtering deposition rate is lower when the secondary target covers the entire ion beam.

Self-organized nickel nanoparticles on nanostructured silicon substrate intermediated by a titanium oxynitride (TiNxOy) interface

NASA Astrophysics Data System (ADS)

Morales, M.; Droppa, R., Jr.; de Mello, S. R. S.; Figueroa, C. A.; Zanatta, A. R.; Alvarez, F.

2018-01-01

In this work we report an experimental approach by combining in situ sequential top-down and bottom-up processes to induce the organization of nanosized nickel particles. The top-down process consists in xenon ion bombardment of a crystalline silicon substrate to generate a pattern, followed by depositing a ˜15 nm titanium oxynitride thin film to act as a metallic diffusion barrier. Then, metallic nanoparticles are deposited by argon ion sputtering a pure nickel target, and the sample is annealed to promote the organization of the nickel nanoparticles (a bottom-up process). According to the experimental results, the surface pattern and the substrate biaxial surface strain are the driving forces behind the alignment and organization of the nickel nanoparticles. Moreover, the ratio between the F of metallic atoms arriving at the substrate relative to its surface diffusion mobility determines the nucleation regime of the nickel nanoparticles. These features are presented and discussed considering the existing technical literature on the subject.

Isotopic Enrichment of Boron in the Sputtering of Boron Nitride with Xenon Ions

NASA Technical Reports Server (NTRS)

Ray, P. K.; Shutthanandan, V.

1998-01-01

An experimental study is described to measure the isotopic enrichment of boron. Xenon ions from 100 eV to 1.5 keV were used to sputter a boron nitride target. An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 microA/sq cm. Xenon ions impinged on the target surface at 50 deg angle to the surface normal. Since boron nitride is an insulator, a flood electron gun was used in our experiments to neutralize the positive charge buildup on the target surface. The sputtered secondary ions of boron were detected by a quadrupole mass spectrometer. The spectrometer entrance aperture was located perpendicular to the ion beam direction and 10 mm away from the target surface. The secondary ion flux was observed to be enriched in the heavy isotopes at lower ion energies. The proportion of heavy isotopes in the sputtered secondary ion flux was found to decrease with increasing primary ion energy from 100 to 350 eV. Beyond 350 eV, light isotopes were sputtered preferentially. The light isotope enrichment factor was observed to reach an asymptotic value of 1.27 at 1.5 keV. This trend is similar to that of the isotopic enrichment observed earlier when copper was sputtered with xenon ions in the same energy range.

Annealing dependence of residual stress and optical properties of TiO2 thin film deposited by different deposition methods.

PubMed

Chen, Hsi-Chao; Lee, Kuan-Shiang; Lee, Cheng-Chung

2008-05-01

Titanium oxide (TiO(2)) thin films were prepared by different deposition methods. The methods were E-gun evaporation with ion-assisted deposition (IAD), radio-frequency (RF) ion-beam sputtering, and direct current (DC) magnetron sputtering. Residual stress was released after annealing the films deposited by RF ion-beam or DC magnetron sputtering but not evaporation, and the extinction coefficient varied significantly. The surface roughness of the evaporated films exceeded that of both sputtered films. At the annealing temperature of 300 degrees C, anatase crystallization occurred in evaporated film but not in the RF ion-beam or DC magnetron-sputtered films. TiO(2) films deposited by sputtering were generally more stable during annealing than those deposited by evaporation.

Sputtering and ion plating for aerospace applications

NASA Technical Reports Server (NTRS)

Spalvins, T.

1981-01-01

Sputtering and ion plating technologies are reviewed in terms of their potential and present uses in the aerospace industry. Sputtering offers great universality and flexibility in depositing any material or in the synthesis of new ones. The sputter deposition process has two areas of interest: thin film and fabrication technology. Thin film sputtering technology is primarily used for aerospace mechanical components to reduce friction, wear, erosion, corrosion, high temperature oxidation, diffusion and fatigue, and also to sputter-construct temperature and strain sensors for aircraft engines. Sputter fabrication is used in intricate aircraft component manufacturing. Ion plating applications are discussed in terms of the high energy evaporant flux and the high throwing power. Excellent adherence and 3 dimensional coverage are the primary attributes of this technology.

Sputtering and ion plating for aerospace applications

NASA Technical Reports Server (NTRS)

Spalvins, T.

1981-01-01

Sputtering and ion plating technologies are reviewed in terms of their potential and present uses in the aerospace industry. Sputtering offers great universality and flexibility in depositing any material or in the synthesis of new ones. The sputter deposition process has two areas of interest: thin film and fabrication technology. Thin film sputtering technology is primarily used for aerospace mechanical components to reduce friction, wear, erosion, corrosion, high temperature oxidation, diffusion and fatigue, and also to sputter-construct temperature and strain sensors for aircraft engines. Sputter fabrication is used in intricate aircraft component manufacturing. Ion plating applications are discussed in terms of the high energy evaporant flux and the high throwing power. Excellent adherence and 3-dimensional coverage are the primary attributes of this technology.

Large Area Microcorrals and Cavity Formation on Cantilevers using a Focused Ion Beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saraf, Laxmikant V.; Britt, David W.

2011-09-14

We utilize focused ion beam (FIB) to explore various sputtering parameters to form large area microcorrals and cavities on cantilevers. Microcorrals were rapidly created by modifying ion beam blur and overlaps. Modification in FIB sputtering parameters affects the periodicity and shape of corral microstructure. Cantilever deflections show ion beam amorphization effects as a function of sputtered area and cantilever base cavities with or without side walls. The FIB sputtering parameters address a method for rapid creation of a cantilever tensiometer with integrated fluid storage and delivery.

High temperature static strain gage development

NASA Technical Reports Server (NTRS)

Hulse, C. O.; Bailey, R. S.; Grant, H. P.; Anderson, W. L.; Przybyszewski, J. S.

1991-01-01

Final results are presented from a program to develop a thin film static strain gage for use on the blades and vanes of running, test stand gas turbine engines with goals of an 3 x 3 mm gage area and total errors of less than 10 pct. of + or - 2,000 microstrain after 50 hrs at 1250 K. Pd containing 13 Wt. pct. Cr was previously identified as a new strain sensor alloy that appeared to be potentially usable to 1250 K. Subsequently, it was discovered, in contrast with its behavior in bulk, that Pd-13Cr suffered from oxidation attack when prepared as a 4.5 micron thick thin film. Continuing problems with electrical leakage to the substrate and the inability of sputtered alumina overcoats to prevent oxidation led to the discovery that sputtered alumina contains appreciable amounts of entrapped argon. After the argon has been exsolved by heating to elevated temperatures, the alumina films undergo a linear shrinkage of about 2 pct. resulting in formation of cracks. These problems can be largely overcome by sputtering the alumina with the substrate heated to 870 K. With 2 micron thick hot sputtered alumina insulation and overcoat films, total 50 hr drifts of about 100 microstrain (2 tests) and about 500 microstrain (1 test) were observed at 1000 and 1100 K, respectively. Results of tests on complete strain gage systems on constant moment bend bars with Pd temperature compensation grids revealed that oxidation of the Pd grid was a major problem even when the grid was overcoated with a hot or cold sputtered alumina overcoat.

Coating multilayer material with improved tribological properties obtained by magnetron sputtering

NASA Astrophysics Data System (ADS)

Mateescu, A. O.; Mateescu, G.; Balasoiu, M.; Pompilian, G. O.; Lungu, M.

2017-02-01

This work is based on the Patent no. RO 128094 B1, granted by the Romanian State Office for Inventions and Trademarks. The goal of the work is to obtain for investigations tribological coatings with multilayer structure with improved tribological properties, deposited by magnetron sputtering process from three materials (sputtering targets). Starting from compound chemical materials (TiC, TiB2 and WC), as sputtering targets, by deposition in argon atmosphere on polished stainless steel, we have obtained, based on the claims of the above patent, thin films of multilayer design with promising results regarding their hardness, elastic modulus, adherence, coefficient of friction and wear resistance. The sputtering process took place in a special sequence in order to ensure better tribological properties to the coating, comparing to those of the individual component materials. The tribological properties, such as the coefficient of friction, are evaluated using the tribometer test.

RF Sputtering for preparing substantially pure amorphous silicon monohydride

DOEpatents

Jeffrey, Frank R.; Shanks, Howard R.

1982-10-12

A process for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicon produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous silicon hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

Solar-Wind Protons and Heavy Ions Sputtering of Lunar Surface Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barghouty, N.; Meyer, Fred W; Harris, Peter R

2011-01-01

Lunar surface materials are exposed to {approx}1 keV/amu solar-wind protons and heavy ions on almost continuous basis. As the lunar surface consists of mostly oxides, these materials suffer, in principle, both kinetic and potential sputtering due to the actions of the solar-wind ions. Sputtering is an important mechanism affecting the composition of both the lunar surface and its tenuous exosphere. While the contribution of kinetic sputtering to the changes in the composition of the surface layer of these oxides is well understood and modeled, the role and implications of potential sputtering remain unclear. As new potential-sputtering data from multi-charged ionsmore » impacting lunar regolith simulants are becoming available from Oak Ridge National Laboratory's MIRF, we examine the role and possible implications of potential sputtering of Lunar KREEP soil. Using a non-equilibrium model we demonstrate that solar-wind heavy ions induced sputtering is critical in establishing the timescale of the overall solar-wind sputtering process of the lunar surface. We also show that potential sputtering leads to a more pronounced and significant differentiation between depleted and enriched surface elements. We briefly discuss the impacts of enhanced sputtering on the composition of the regolith and the exosphere, as well as of solar-wind sputtering as a source of hydrogen and water on the moon.« less

Method to estimate the electron temperature and neutral density in a plasma from spectroscopic measurements using argon atom and ion collisional-radiative models.

PubMed

Sciamma, Ella M; Bengtson, Roger D; Rowan, W L; Keesee, Amy; Lee, Charles A; Berisford, Dan; Lee, Kevin; Gentle, K W

2008-10-01

We present a method to infer the electron temperature in argon plasmas using a collisional-radiative model for argon ions and measurements of electron density to interpret absolutely calibrated spectroscopic measurements of argon ion (Ar II) line intensities. The neutral density, and hence the degree of ionization of this plasma, can then be estimated using argon atom (Ar I) line intensities and a collisional-radiative model for argon atoms. This method has been tested for plasmas generated on two different devices at the University of Texas at Austin: the helicon experiment and the helimak experiment. We present results that show good correlation with other measurements in the plasma.

Making AlN(x) Tunnel Barriers Using a Low-Energy Nitrogen-Ion Beam

NASA Technical Reports Server (NTRS)

Kaul, Anupama; Kleinsasser, Alan; Bumble, Bruce; LeDuc, Henry; Lee, Karen

2005-01-01

A technique based on accelerating positive nitrogen ions onto an aluminum layer has been demonstrated to be effective in forming thin (<2 nm thick) layers of aluminum nitride (AlN(x)) for use as tunnel barriers in Nb/Al-AlN(x)/Nb superconductor/insulator/ superconductor (SIS) Josephson junctions. AlN(x) is the present material of choice for tunnel barriers because, to a degree greater than that of any other suitable material, it offers the required combination of low leakage current at high current density and greater thermal stability. While ultra-thin AlN films with good thickness and stoichiometry control are easily formed using techniques such as reactive molecular beam epitaxy and chemical vapor deposition, growth temperatures of 900 C are necessary for the dissociative adsorption of nitrogen from either nitrogen (N2) or ammonia (NH3). These growth temperatures are prohibitively high for the formation of tunnel barriers on Nb films because interfacial reactions at temperatures as low as 200 to 300 C degrade device properties. Heretofore, deposition by reactive sputtering and nitridation of thin Al layers with DC and RF nitrogen plasmas have been successfully used to form AlN barriers in SIS junctions. However, precise control over critical current density Jc has proven to be a challenge, as is attaining adequate process reproducibility from system to system. The present ion-beam technique is an alternative to the plasma or reactive sputtering techniques as it provides a highly controlled arrival of reactive species, independent of the electrical conditions of the substrate or vacuum chamber. Independent and accurate control of parameters such as ion energy, flux, species, and direction promises more precise control of film characteristics such as stoichiometry and thickness than is the case with typical plasma processes. In particular, the background pressure during ion-beam nitride growth is 2 or 3 orders of magnitude lower, minimizing the formation of compounds with contaminants, which is critical in devices the performance of which is dictated by interfacial characteristics. In addition, the flux of incoming species can be measured in situ using ion probes so that the dose can be controlled accurately. The apparatus used in the present ion-beam technique includes a vacuum chamber containing a commercial collimated- ion-beam source, a supply of nitrogen and argon, and an ion probe for measuring the ion dose. Either argon or nitrogen can be used as the feed gases for the ion source, depending on whether cleaning of the substrate or growth of the nitride, respectively, is desired. Once the Nb base electrode and Al proximity layer have been deposited, the N2 gas line to the ion beam is vented and purged, and the ion-source is turned on until a stable discharge is obtained. The substrate is moved over the ion-beam source to expose the Al surface layer to the ion beam (see figure) for a specified duration for the formation of the nitride tunnel barrier. Next, the Nb counter-electrode layer is deposited on the nitride surface layer. The Nb/Al- AlN(x)/Nb-trilayer-covered substrate is then patterned into individual devices by use of conventional integrated-circuit processing techniques.

Influence of ion source configuration and its operation parameters on the target sputtering and implantation process.

PubMed

Shalnov, K V; Kukhta, V R; Uemura, K; Ito, Y

2012-06-01

In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to α-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N(2)-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling.

Comparative studies on damages to organic layer during the deposition of ITO films by various sputtering methods

NASA Astrophysics Data System (ADS)

Lei, Hao; Wang, Meihan; Hoshi, Yoichi; Uchida, Takayuki; Kobayashi, Shinichi; Sawada, Yutaka

2013-11-01

Aluminum (III) bis(2-methyl-8-quninolinato)-4-phenylphenolate (BAlq) was respectively bombarded and irradiated by Ar ions, oxygen ions, electron beam and ultraviolet light to confirm damages during the sputter-deposition of transparent conductive oxide (TCO) on organic layer. The degree of damage was evaluated by the photoluminescence (PL) spectra of BAlq. The results confirmed the oxygen ions led to a larger damage and were thought to play the double roles of bombardment to organic layer and reaction with organic layer as well. The comparative studies on PL spectra of BAlq after the deposition of TCO films by various sputtering systems, such as conventional magnetron sputtering (MS), low voltage sputtering (LVS) and kinetic-energy-control-deposition (KECD) system, facing target sputtering (FTS) were performed. Relative to MS, LVS and KECD system, FTS can completely suppress the bombardment of the secondary electrons and oxygen negative ions, and keep a higher deposition rate simultaneously, thus it is a good solution to attain a low-damage sputter-deposition.

Surface characterization of low-temperature grown yttrium oxide

NASA Astrophysics Data System (ADS)

Krawczyk, Mirosław; Lisowski, Wojciech; Pisarek, Marcin; Nikiforow, Kostiantyn; Jablonski, Aleksander

2018-04-01

The step-by-step growth of yttrium oxide layer was controlled in situ using X-ray photoelectron spectroscopy (XPS). The O/Y atomic concentration (AC) ratio in the surface layer of finally oxidized Y substrate was found to be equal to 1.48. The as-grown yttrium oxide layers were then analyzed ex situ using combination of Auger electron spectroscopy (AES), elastic-peak electron spectroscopy (EPES) and scanning electron microscopy (SEM) in order to characterize their surface chemical composition, electron transport phenomena and surface morphology. Prior to EPES measurements, the Y oxide surface was pre-sputtered by 3 kV argon ions, and the resulting AES-derived composition was found to be Y0.383O0.465C0.152 (O/Y AC ratio of 1.21). The SEM images revealed different surface morphology of sample before and after Ar sputtering. The oxide precipitates were observed on the top of un-sputtered Y oxide layer, whereas the oxide growth at the Ar ion-sputtered surface proceeded along defects lines normal to the layer plane. The inelastic mean free path (IMFP) characterizing electron transport was evaluated as a function of energy in the range of 0.5-2 keV from the EPES method. Two reference materials (Ni and Au) were used in these measurements. Experimental IMFPs determined for the Y0.383O0.465C0.152 and Y2O3 surface compositions, λ, were uncorrected for surface excitations and approximated by the simple function λ = kEp at electron energies E between 500 eV and 2000 eV, where k and p were fitted parameters. These values were also compared with IMFPs resulting from the TPP-2 M predictive equation for both oxide compositions. The fitted functions were found to be reasonably consistent with the measured and predicted IMFPs. In both cases, the average value of the mean percentage deviation from the fits varied between 5% and 37%. The IMFPs measured for Y0.383O0.465C0.152 surface composition were found to be similar to the IMFPs for Y2O3.

Xenon Sputter Yield Measurements for Ion Thruster Materials

NASA Technical Reports Server (NTRS)

Williams, John D.; Gardner, Michael M.; Johnson, Mark L.; Wilbur, Paul J.

2003-01-01

In this paper, we describe a technique that was used to measure total and differential sputter yields of materials important to high specific impulse ion thrusters. The heart of the technique is a quartz crystal monitor that is swept at constant radial distance from a small target region where a high current density xenon ion beam is aimed. Differential sputtering yields were generally measured over a full 180 deg arc in a plane that included the beam centerline and the normal vector to the target surface. Sputter yield results are presented for a xenon ion energy range from 0.5 to 10 keV and an angle of incidence range from 0 deg to 70 deg from the target surface normal direction for targets consisting of molybdenum, titanium, solid (Poco) graphite, and flexible graphite (grafoil). Total sputter yields are calculated using a simple integration procedure and comparisons are made to sputter yields obtained from the literature. In general, the agreement between the available data is good. As expected for heavy xenon ions, the differential and total sputter yields are found to be strong functions of angle of incidence. Significant under- and over-cosine behavior is observed at low- and high-ion energies, respectively. In addition, strong differences in differential yield behavior are observed between low-Z targets (C and Ti) and high-Z targets (Mo). Curve fits to the differential sputter yield data are provided. They should prove useful to analysts interested in predicting the erosion profiles of ion thruster components and determining where the erosion products re-deposit.

Effects of crystallographic and geometric orientation on ion beam sputtering of gold nanorods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinks, J. A.; Hibberd, F.; Hattar, K.

Nanostructures may be exposed to irradiation during their manufacture, their engineering and whilst in-service. The consequences of such bombardment can be vastly different from those seen in the bulk. In this paper, we combine transmission electron microscopy with in situ ion irradiation with complementary computer modelling techniques to explore the physics governing the effects of 1.7 MeV Au ions on gold nanorods. Phenomena surrounding the sputtering and associated morphological changes caused by the ion irradiation have been explored. In both the experiments and the simulations, large variations in the sputter yields from individual nanorods were observed. These sputter yields havemore » been shown to correlate with the strength of channelling directions close to the direction in which the ion beam was incident. Finally, craters decorated by ejecta blankets were found to form due to cluster emission thus explaining the high sputter yields.« less

Effects of crystallographic and geometric orientation on ion beam sputtering of gold nanorods

DOE PAGES

Hinks, J. A.; Hibberd, F.; Hattar, K.; ...

2018-01-11

Nanostructures may be exposed to irradiation during their manufacture, their engineering and whilst in-service. The consequences of such bombardment can be vastly different from those seen in the bulk. In this paper, we combine transmission electron microscopy with in situ ion irradiation with complementary computer modelling techniques to explore the physics governing the effects of 1.7 MeV Au ions on gold nanorods. Phenomena surrounding the sputtering and associated morphological changes caused by the ion irradiation have been explored. In both the experiments and the simulations, large variations in the sputter yields from individual nanorods were observed. These sputter yields havemore » been shown to correlate with the strength of channelling directions close to the direction in which the ion beam was incident. Finally, craters decorated by ejecta blankets were found to form due to cluster emission thus explaining the high sputter yields.« less

Transition rate diagrams and excitation of titanium in a glow discharge in argon and neon

NASA Astrophysics Data System (ADS)

Weiss, Zdeněk; Steers, Edward B. M.; Pickering, Juliet C.

2018-06-01

Emission spectra of titanium in a Grimm-type glow discharge in argon and neon were studied using the formalism of transition rate diagrams. Ti I spectra in argon and neon discharges are similar, without signs of selective excitation, and populations of Ti I levels exhibit a decreasing trend as function of energy, except for some scatter. A major excitation process of Ti II in argon discharge is charge transfer from argon ions to neutral titanium. In neon discharge, a strong selective excitation was observed of Ti II levels at ≈13.3-13.4 eV relative to the Ti I ground state. It was attributed to charge transfer from doubly charged titanium ions to neutral titanium, while the Ti++ ions are produced by charge transfer and ionization of neutral titanium by neon ions. Cascade excitation is important for Ti II levels up to an energy of ≈13 eV relative to the Ti I ground state, both in argon and neon discharges.

Microscopic morphology evolution during ion beam smoothing of Zerodur® surfaces.

PubMed

Liao, Wenlin; Dai, Yifan; Xie, Xuhui; Zhou, Lin

2014-01-13

Ion sputtering of Zerodur material often results in the formation of nanoscale microstructures on the surfaces, which seriously influences optical surface quality. In this paper, we describe the microscopic morphology evolution during ion sputtering of Zerodur surfaces through experimental researches and theoretical analysis, which shows that preferential sputtering together with curvature-dependent sputtering overcomes ion-induced smoothing mechanisms leading to granular nanopatterns formation in morphology and the coarsening of the surface. Consequently, we propose a new method for ion beam smoothing (IBS) of Zerodur optics assisted by deterministic ion beam material adding (IBA) technology. With this method, Zerodur optics with surface roughness down to 0.15 nm root mean square (RMS) level is obtained through the experimental investigation, which demonstrates the feasibility of our proposed method.

Effects of argon sputtering and UV-ozone radiation on the physico-chemical surface properties of ITO

NASA Astrophysics Data System (ADS)

Che, Hui; El Bouanani, M.

2018-01-01

X-ray photoelectron spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS) were used to evaluate and determine the effects of 1 KeV Ar+ irradiation (sputtering) on the surface chemical composition and work function of Indium Thin Oxide (ITO). While Ar+ sputtering removes carbon-based surface contaminants, it also modifies the Sn-rich surface of ITO and leads to a reduction of the oxidation state of Sn from Sn4+ to Sn2+. The decrease in the work function of ITO is directly correlated to the decrease of Sn atomic concentration in the Sn-rich top surface layer and the reduction of the oxidation state of surface Sn.

Molybdenum and carbon atom and carbon cluster sputtering under low-energy noble gas plasma bombardment

NASA Astrophysics Data System (ADS)

Oyarzabal, Eider

Exit-angle resolved Mo atom sputtering yield under Xe ion bombardment and carbon atom and cluster (C2 and C3) sputtering yields under Xe, Kr, Ar, Ne and He ion bombardment from a plasma are measured for low incident energies (75--225 eV). An energy-resolved quadrupole mass spectrometer (QMS) is used to detect the fraction of un-scattered sputtered neutrals that become ionized in the plasma; the angular distribution is obtained by changing the angle between the target and the QMS aperture. A one-dimensional Monte Carlo code is used to simulate the interaction of the plasma and the sputtered particles between the sample and the QMS. The elastic scattering cross-sections of C, C2 and C3 with the different bombarding gas neutrals is obtained by varying the distance between the sample and the QMS and by performing a best fit of the simulation results to the experimental results. Because the results obtained with the QMS are relative, the Mo atom sputtering results are normalized to the existing data in the literature and the total sputtering yield for carbon (C+C 2+C3) for each bombarding gas is obtained from weight loss measurements. The absolute sputtering yield for C, C2 and C 3 is then calculated from the integration of the measured angular distribution, taking into account the scattering and ionization of the sputtered particles between the sample and the QMS. The angular sputtering distribution for Mo has a maximum at theta=60°, and this maximum becomes less pronounced as the incident ion energy increases. The results of the Monte Carlo TRIDYN code simulation for the angular distribution of Mo atoms sputtered by Xe bombardment are in agreement with the experiments. For carbon sputtering under-cosine angular distributions of the sputtered atoms and clusters for all the studied bombarding gases are also observed. The C, C2 and C3 sputtering yield data shows a clear decrease of the atom to cluster (C/C2 and C/C3) sputtering ratio as the incident ion mass increases, changing from a carbon atom preferential erosion for the lower incident ion masses (He, Ne and Ar) to a cluster preferential erosion for the higher incident ion masses (Kr and Xe).

Facing-target mid-frequency magnetron reactive sputtered hafnium oxide film: Morphology and electrical properties

NASA Astrophysics Data System (ADS)

Zhang, Yu; Xu, Jun; Wang, You-Nian; Choi, Chi Kyu; Zhou, Da-Yu

2016-03-01

Amorphous hafnium dioxide (HfO2) film was prepared on Si (100) by facing-target mid-frequency reactive magnetron sputtering under different oxygen/argon gas ratio at room temperature with high purity Hf target. 3D surface profiler results showed that the deposition rates of HfO2 thin film under different O2/Ar gas ratio remain unchanged, indicating that the facing target midfrequency magnetron sputtering system provides effective approach to eliminate target poisoning phenomenon which is generally occurred in reactive sputtering procedure. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) demonstrated that the gradual reduction of oxygen vacancy concentration and the densification of deposited film structure with the increase of oxygen/argon (O2/Ar) gas flow ratio. Atomic force microscopy (AFM) analysis suggested that the surface of the as-deposited HfO2 thin film tends to be smoother, the root-meansquare roughness (RMS) reduced from 0.876 nm to 0.333 nm while O2/Ar gas flow ratio increased from 1/4 to 1/1. Current-Voltage measurements of MOS capacitor based on Au/HfO2/Si structure indicated that the leakage current density of HfO2 thin films decreased by increasing of oxygen partial pressure, which resulted in the variations of pore size and oxygen vacancy concentration in deposited thin films. Based on the above characterization results the leakage current mechanism for all samples was discussed systematically.

Sputtering of Lunar Regolith by Solar Wind Protons and Heavy Ions, and General Aspects of Potential Sputtering

NASA Technical Reports Server (NTRS)

Alnussirat, S. T.; Sabra, M. S.; Barghouty, A. F.; Rickman, Douglas L.; Meyer, F.

2014-01-01

New simulation results for the sputtering of lunar soil surface by solar-wind protons and heavy ions will be presented. Previous simulation results showed that the sputtering process has significant effects and plays an important role in changing the surface chemical composition, setting the erosion rate and the sputtering process timescale. In this new work and in light of recent data, we briefly present some theoretical models which have been developed to describe the sputtering process and compare their results with recent calculation to investigate and differentiate the roles and the contributions of potential (or electrodynamic) sputtering from the standard (or kinetic) sputtering.

Sputtering of Lunar Regolith Simulant by Protons and Multicharged Heavy Ions at Solar Wind Energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, Fred W; Harris, Peter R; Taylor, C. N.

2011-01-01

We report preliminary results on sputtering of a lunar regolith simulant at room temperature by singly and multiply charged solar wind ions using quadrupole and time-of-flight (TOF) mass spectrometry approaches. Sputtering of the lunar regolith by solar-wind heavy ions may be an important particle source that contributes to the composition of the lunar exosphere, and is a possible mechanism for lunar surface ageing and compositional modification. The measurements were performed in order to assess the relative sputtering efficiency of protons, which are the dominant constituent of the solar wind, and less abundant heavier multicharged solar wind constituents, which have highermore » physical sputtering yields than same-velocity protons, and whose sputtering yields may be further enhanced due to potential sputtering. Two different target preparation approaches using JSC-1A AGGL lunar regolith simulant are described and compared using SEM and XPS surface analysis.« less

Sputtering by the Solar Wind: Effects of Variable Composition

NASA Technical Reports Server (NTRS)

Killen, R. M.; Arrell, W. M.; Sarantos, M.; Delory, G. T.

2011-01-01

It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that there is no increase in the sputtering yield caused by highly charged heavy ions for metallic and for semiconducting surfaces, but the sputter yield can be noticeably increased in the case of a good insulating surface. Recently measurements of the solar wind composition have become available. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. Whereas many previous calculations of sputtering were limited to the effects of proton bombardment. we show that the heavy ion component. especially the He++ component. can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. We will discuss sputtering of both neutrals and ions.

Deuterium supersaturation in low-energy plasma-loaded tungsten surfaces

NASA Astrophysics Data System (ADS)

Gao, L.; Jacob, W.; von Toussaint, U.; Manhard, A.; Balden, M.; Schmid, K.; Schwarz-Selinger, T.

2017-01-01

Fundamental understanding of hydrogen-metal interactions is challenging due to a lack of knowledge on defect production and/or evolution upon hydrogen ingression, especially for metals undergoing hydrogen irradiation with ion energy below the displacement thresholds reported in literature. Here, applying a novel low-energy argon-sputter depth profiling method with significantly improved depth resolution for tungsten (W) surfaces exposed to deuterium (D) plasma at 300 K, we show the existence of a 10 nm thick D-supersaturated surface layer (DSSL) with an unexpectedly high D concentration of ~10 at.% after irradiation with ion energy of 215 eV. Electron back-scatter diffraction reveals that the W lattice within this DSSL is highly distorted, thus strongly blurring the Kikuchi pattern. We explain this strong damage by the synergistic interaction of energetic D ions and solute D atoms with the W lattice. Solute D atoms prevent the recombination of vacancies with interstitial W atoms, which are produced by collisions of energetic D ions with W lattice atoms (Frenkel pairs). This proposed damaging mechanism could also be active on other hydrogen-irradiated metal surfaces. The present work provides deep insight into hydrogen-induced lattice distortion at plasma-metal interfaces and sheds light on its modelling work.

Adaptation of ion beam technology to microfabrication of solid state devices and transducers

NASA Technical Reports Server (NTRS)

Topich, J. A.

1977-01-01

It was found that ion beam texturing of silicon surfaces can be used to increase the effective surface area of MOS capacitors. There is, however, a problem with low dielectric breakdown. Preliminary work was begun on the fabrication of ion implanted resistors on textured surfaces and the potential improvement of wire bond strength by bonding to a textured surface. In the area of ion beam sputtering, the techniques for sputtering PVC were developed. A PVC target containing valinomycin was used to sputter an ion selective membrane on a field effect transistor to form a potassium ion sensor.

Dopant-assisted direct analysis in real time mass spectrometry with argon gas.

PubMed

Cody, Robert B; Dane, A John

2016-05-30

Dopants used with Atmospheric Pressure Photoionization (APPI) were examined with the Direct Analysis in Real Time (DART ® ) ion source operated with argon gas. Charge-exchange and proton transfer reactions were observed by adding toluene, anisole, chlorobenzene and acetone to the DART gas stream, complementing the information obtained by helium DART. Mass spectra were acquired with a time-of-flight mass spectrometer equipped with a DART ion source operated with argon gas. A syringe pump was used to introduce dopants directly into the DART gas stream through deactivated fused-silica capillary tubing. Samples including polycyclic aromatic hydrocarbons (PAHs), diesel fuel, trinitrotoluene and cannabinoids were deposited onto the sealed end of melting tube, allowed to dry, and the tube was then suspended in the dopant-enhanced DART gas stream. PAHs could be detected as molecular ions at concentrations in the low parts-per-billion range by using a solution of 0.5% anisole in toluene as a dopant. Argon DART analysis of a diesel fuel sample with the same dopant mixture showed a simpler mass spectrum than obtained by using helium DART. The argon DART mass spectrum was dominated by molecular ions for aromatic compounds, whereas the helium DART mass spectrum showed both molecular ions and protonated molecules. In contrast O 2 - attachment DART showed saturated hydrocarbons and oxygen-containing species. Mass spectra for trinitrotoluene with argon DART in negative-ion mode showed a prominent [M - H] - peak, whereas conventional helium DART showed both M - and [M - H] - . Lastly, in analogy to a report in the literature using APPI, positive ions produced by argon DART ionization for delta-9-tetrahydrocannabinol (THC) and cannabidiol showed distinctive product-ion mass spectra. Dopant-assisted argon DART operates by a mechanism that is analogous to those proposed for dopant-assisted atmospheric-pressure photoionization. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auciello, O.; Ameen, M.S.; Graettinger, T.M.

Ion beam sputtering is presently used to deposit films from single phase YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} targets. Generally, Ar+ ion beams ({approx}1500 eV) produced by Kaufman-type ion sources are used for this purpose. It has been observed that these ion beams induce compositional and morphological changes on the polycrystalline ceramic target surface, which results in the composition of sputtered flux displaying a time-dependent behavior. This in turn may lead to undesirably long times for reaching steady state conditions in the sputtering process.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auciello, O.; Ameen, M.S.; Graettinger, T.

Ion beam sputtering is presently used to deposit films from single phase YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} targets. Generally, Ar{sup +} ion beams ({similar to}1500 eV) produced by Kaufman-type ion sources are used for this purpose. It has been observed that these ion beams induce compositional and morphological changes on the polycrystalline ceramic target surface, which results in the composition of sputtered flux displaying a time-dependent behavior. This in turn may lead to undesirably long times for reaching steady state conditions in the sputtering process.

Sputtering yields and surface chemical modification of tin-doped indium oxide in hydrocarbon-based plasma etching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hu; Karahashi, Kazuhiro; Hamaguchi, Satoshi, E-mail: hamaguch@ppl.eng.osaka-u.ac.jp

2015-11-15

Sputtering yields and surface chemical compositions of tin-doped indium oxide (or indium tin oxide, ITO) by CH{sup +}, CH{sub 3}{sup +}, and inert-gas ion (He{sup +}, Ne{sup +}, and Ar{sup +}) incidence have been obtained experimentally with the use of a mass-selected ion beam system and in-situ x-ray photoelectron spectroscopy. It has been found that etching of ITO is chemically enhanced by energetic incidence of hydrocarbon (CH{sub x}{sup +}) ions. At high incident energy incidence, it appears that carbon of incident ions predominantly reduce indium (In) of ITO and the ITO sputtering yields by CH{sup +} and CH{sub 3}{sup +}more » ions are found to be essentially equal. At lower incident energy (less than 500 eV or so), however, a hydrogen effect on ITO reduction is more pronounced and the ITO surface is more reduced by CH{sub 3}{sup +} ions than CH{sup +} ions. Although the surface is covered more with metallic In by low-energy incident CH{sub 3}{sup +} ions than CH{sup +} ions and metallic In is in general less resistant against physical sputtering than its oxide, the ITO sputtering yield by incident CH{sub 3}{sup +} ions is found to be lower than that by incident CH{sup +} ions in this energy range. A postulation to account for the relation between the observed sputtering yield and reduction of the ITO surface is also presented. The results presented here offer a better understanding of elementary surface reactions observed in reactive ion etching processes of ITO by hydrocarbon plasmas.« less

Sputtering Erosion in Ion and Plasma Thrusters

NASA Technical Reports Server (NTRS)

Ray, Pradosh K.

1996-01-01

Low energy sputtering of molybdenum, tantalum and boron nitride with xenon ions are being studied using secondary neutral and secondary ion mass spectrometry (SNMS/SIMS). An ultrahigh vacuum chamber was used to conduct the experiment at a base pressure of 1x10(exp -9) torr. The primary ion beam is generated by an ion gun which is capable of delivering ion currents in the range of 20 to 500 nA. The ion beam can be focused to a spot size of approximately 1 mm in diameter. The mass spectrometer is positioned 10 mm from the target and 90 deg to the primary ion beam direction. SNMS and SIMS spectra were collected at various incident angles and different ion energies. For boron nitride sputtering, the target was flooded with an electron beam to neutralize the charge buildup on the surface. In the SNMS mode, sputtering of Mo and Ta can be detected at an ion energy as low as 100 eV whereas in boron nitride the same was observed up to an energy of 300 eV. However, in the positive-SIMS mode, the sputtering of Mo was observed at 10 eV incident ion energy. The SIMS spectra obtained for boron nitride clearly identifies the two isotopes of boron as well as cluster ions such as B2(sup +) and molecular ions such as BN(sup +). From the angle versus yields measurements, it was found that the maximum SNMS yield shifts towards lower incident angles at low ion energies for all three samples.

Ion-stimulated mass transport in nanoscale morphology evolution

NASA Astrophysics Data System (ADS)

George, Henry Bola

We observe temporal evolution of two distinct lateral length scales in surface topography following low energy, E, argon ion (Ar+) irradiation of Si(001). From real-space AFM topographs, we observe that the short-wavelength, lambda (high-wavenumber, q) evolve as nearly isotropic dots while the longer-lambda (low- q) features appear as isotropic "rings" at normal incidence and as anisotropic ripples at off-normal incidence with their wavevector orthogonal to the ion beam. We explain our results in terms of an interplay between smoothening by ion-enhanced viscous flow and roughening driven by ion sputtering (for high-q features) or elastic strain energy relief (for low- q features). Our proposed mechanisms also explain the weak temperature and flux dependence of both wavelengths. We also observe stable flat surfaces following irradiation at incidence angles greater than 20° from normal, E > 500 eV and temperature > 300°C. To explain non-diverging wavelengths as the smoothening boundary is approached, we present evidence that non-local terms are needed in the height evolution equation. We report the influence of pre-patterned boundaries in guiding ripples appearing during uniform irradiation at high temperatures. Compared to untemplated samples, we observe that the long-range order of the guided ripples is significantly enhanced. We develop a scalar figure of merit to characterize the degree of order of the patterns. We observe that templating is most efficient when the boundaries are separated by an integer multiple of the spontaneously arising wavelength. We report new observations following ion sculpting of nanopores. Among these are: (1) The formation of nanopores is not limited to insulators: we successfully close pores in other materials including silicon dioxide, amorphous silicon (semiconductor) and palladium silicide (metallic glass). (2) Pores retain "memory" of their initial radius: at the same instantaneous radius, pores that started off smaller require less argon fluence for closure. (3) In some cases the closure rate increases strongly with temperature but saturates at higher temperatures. As a partial explanation to these observations, we propose that anisotropic strain deformation is not limited to MeV irradiation of amorphous materials but plays an important role even in the keV regime.

Sputtering phenomena of discharge chamber components in a 30-cm diameter Hg ion thruster

NASA Technical Reports Server (NTRS)

Mantenieks, M. A.; Rawlin, V. K.

1976-01-01

Sputtering and deposition rates were measured for discharge chamber components of a 30-cm diameter mercury ion thruster. It was found that sputtering rates of the screen grid and cathode baffle were strongly affected by geometry of the baffle holder. Sputtering rates of the baffle and screen grid were reduced to 80 and 125 A/hr, respectively, by combination of appropriate geometry and materials selections. Sputtering rates such as these are commensurate with thruster lifetimes of 15,000 hours or more. A semiempirical sputtering model showed good agreement with the measured values.

RF sputtering for controlling dihydride and monohydride bond densities in amorphous silicon hydride

DOEpatents

Jeffery, F.R.; Shanks, H.R.

1980-08-26

A process is described for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicone produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous solicone hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

Sputtering of sodium and potassium from nepheline: Secondary ion yields and velocity spectra

NASA Astrophysics Data System (ADS)

Martinez, R.; Langlinay, Th.; Ponciano, C. R.; da Silveira, E. F.; Palumbo, M. E.; Strazzulla, G.; Brucato, J. R.; Hijazi, H.; Agnihotri, A. N.; Boduch, P.; Cassimi, A.; Domaracka, A.; Ropars, F.; Rothard, H.

2017-09-01

Silicates are the dominant surface material of many Solar System objects, which are exposed to ion bombardment by solar wind ions and cosmic rays. Induced physico-chemical processes include sputtering which can contribute to the formation of an exosphere. We have measured sputtering yields and velocity spectra of secondary ions ejected from nepheline, an aluminosilicate thought to be a good analogue for Mercury's surface, as a laboratory approach to understand the evolution of silicate surfaces and the presence of Na and K vapor in the exosphere. Experiments were performed with highly charged ion beams (keV/u-MeV/u) delivered by GANIL using an imaging XY-TOF-SIMS device under UHV conditions. The fluence dependence of sputtering yields gives information about the evolution of surface stoichiometry during irradiation. From the energy distributions N(E) of sputtered particles, the fraction of particles which could escape from the gravitational field of Mercury, and of those falling back and possibly contributing to populate the exosphere can be roughly estimated.

Industrial ion source technology

NASA Technical Reports Server (NTRS)

Kaufman, H. R.; Robinson, R. S.

1978-01-01

An analytical model was developed to describe the development of a coned surface texture with ion bombardment and simultaneous deposition of an impurity. A mathematical model of sputter deposition rate from a beveled target was developed in conjuction with the texturing models to provide an important input to that model. The establishment of a general procedure that will allow the treatment of manay different sputtering configurations is outlined. Calculation of cross sections for energetic binary collisions was extened to Ar, Kr.. and Xe with total cross sections for viscosity and diffusion calculated for the interaction energy range from leV to 1000eV. Physical sputtering and reactive ion etching experiments provided experimental data on the operating limits of a broad beam ion source using CF4 as a working gas to produce reactive species in a sputtering beam. Magnetic clustering effects are observed when Al is seeded with Fe and sputtered with Ar(?) ions. Silicon was textured at a micron scale by using a substrate temperature of 600 C.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Targove, J.D.

The columnar microstructure of most thermally evaporated thin films detrimentally affects many of their properties through a reduction in packing density. In this work, the author investigated ion-assisted deposition as a means of disrupting this columnar growth for a number of coating materials. A Kaufman hot-cathode ion source bombarded thermally evaporated films with low-energy (<1000 eV) positive ions during deposition in a cryopumped box coater. The author investigated MgF/sub 2/, Na/sub 3/AlF/sub 6/, AlF/sub 3/, LaF/sub 3/,CeF/sub 3/,NdF/sub 3/,Al/sub 2/O/sub 3/, and AlN. Argon ion bombardment of the fluoride coatings increased their packing densities dramatically. He achieved packing densities nearmore » unity without significant absorption for MgF/sub 2/,LaF/sub 3/, and NdF/sub 3/, while Na/sub 3/AlF/sub 6/,AlF/sub 3/, and CeF/sub 3/ began to absorb before unity packing density could be achieved. Fluorine was preferentially sputtered by the ion bombardment, creating anion vacancies. The films adsorbed water vapor and hydroxyl radicals from the residual chamber atmosphere. These filled the vacancy sites, eliminating absorption in the visible, but the oxygen complexes caused increased absorption in the ultraviolet. For LaF/sub 3/ and NdF/sub 3/, a sufficient amount of oxygen caused a phase transformation from the fluoride phase to an oxyfluoride phase.« less

Effect of magnetic field on spoke behaviour in HiPIMS plasma

NASA Astrophysics Data System (ADS)

Hnilica, J.; Klein, P.; Šlapanská, M.; Fekete, M.; Vašina, P.

2018-03-01

The objective of this paper is to study the effect of magnetic field strength on spoke behaviour in a high power impulse magnetron sputtering discharge. In three magnetic field configurations, a broad range of experimental conditions was investigated by high-speed camera imaging. The dual image feature of the employed camera enabled us to determine the shape and spoke mode number, as well as the velocity of the spokes. Five distinct spoke shapes were detected. For each magnetic field, a map was created relating the occurrence of the spoke shape with the discharge conditions. Similarly, the spoke mode number, as well as the spoke velocity, was found to be strongly dependent on the discharge conditions. Based on the optical emission results, it was proposed that the trailing edge of the triangular spoke is related to the production of secondary electrons created by argon ions on the spoke edges, while in the case of a round spoke shape, the secondary electrons are mainly created by multiple charged titanium ions in the centre of the spoke.

The new applications of sputtering and ion plating

NASA Technical Reports Server (NTRS)

Spalvins, T.

1977-01-01

The potential industrial applications of sputtering and ion plating are strictly governed by the unique features these methods possess. The outstanding features of each method, the resultant coating characteristics and the various sputtering modes and configurations are discussed. New, more complex coatings and deposits can be developed such as graded composition structures (metal-ceramic seals), laminated and dispersion strengthened composites which improve the mechanical properties and high temperature stability. Specific industrial areas where future effort of sputtering and ion plating will concentrate to develop intricate alloy or compound coatings and solve difficult problem areas are discussed.

Adaptation of ion beam technology to microfabrication of solid state devices and transducers

NASA Technical Reports Server (NTRS)

Topich, J. A.

1978-01-01

A number of areas were investigated to determine the potential uses of ion beam techniques in the construction of solid state devices and transducers and the packaging of implantable electronics for biomedical applications. The five areas investigated during the past year were: (1) diode-like devices fabricated on textured silicon; (2) a photolithographic technique for patterning ion beam sputtered PVC (polyvinyl chloride); (3) use of sputtered Teflon as a protective coating for implantable pressure sensors; (4) the sputtering of Macor to seal implantable hybrid circuits; and (5) the use of sputtered Teflon to immobilize enzymes.

Theoretical investigations on plasma processes in the Kaufman thruster. [electron and ion velocity distribution

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.

1974-01-01

An analysis of the sputtering of metal surfaces and grids by ions of medium energies is given and it is shown that an exact, nonlinear, hyperbolic wave equation for the temperature field describes the transient transport of heat in metals. Quantum statistical and perturbation theoretical analysis of surface sputtering by low energy ions are used to develop the same expression for the sputtering rate. A transport model is formulated for the deposition of sputtered atoms on system components. Theoretical efforts in determining the potential distribution and the particle velocity distributions in low pressure discharges are briefly discussed.

Temperature dependent structural and magnetic study of Co-sputtered Fe-Al thin film

NASA Astrophysics Data System (ADS)

Vyas, Anupam; Brajpuriya, Ranjeet

2017-05-01

The authors have deposited co-sputtered Fe-Al thin film on a glass substrate. It is the first ever reporting of Fe and Al co-sputtering in an Argon atmosphere under vacuum conditions. The sample was annealed at 200°C, 300°C, 400°C, so as to allow different phase formation in it. To study the structural and magnetic properties of the samples the GIXRD, XRR and MOKE measurements were done. After annealing at 400°C we observed disordered FeAl formation and which after further converted to more ordered phase which is also confirmed from reflectivity measurements. The magnetic measurement shows the magnetic nature of the sample even after annealing at 400°C/5hr.

Charge exchange of highly charged argon ions as a function of projectile energy

NASA Astrophysics Data System (ADS)

Allen, F. I.; Biedermann, C.; Radtke, R.; Fussmann, G.

2007-03-01

X-ray emission of highly charged argon ions following charge exchange collisions with argon atoms has been measured as a function of projectile energy. The ions are extracted from the Electron Beam Ion Trap (EBIT) in Berlin and selected according to their massto-charge ratios. Experiments focussed on hydrogen-like and bare argon ions which were decelerated from 125q eV/amu to below 0.25q eV/amu prior to interaction with an argon gas target. The x-ray spectra recorded probe the cascading transitions resulting from electron capture into Rydberg states and are found to vary significantly with collision velocity. This indicates a shift in the orbital angular momentum of the capture state. Hardness ratios are observed to increase with decreasing projectile energy though at a rate which differs from the results of simulations. For comparison, measurements of the x-ray emission following charge exchange within the trap were carried out and are in agreement with the findings of the EBIT group at LLNL. Both of these in situ measurements, however, are in discrepancy with the results of the experiments using extracted ions.

Industrial potential, uses, and performance of sputtered and ion plated films

NASA Technical Reports Server (NTRS)

Spalvins, T.

1979-01-01

The sputtering and ion plating technology is reviewed in terms of their potential, uses and performance. It offers the greatest flexibility in coating preparation, since coatings can be tailored in any preferred chemical combination, and graded type interfaces (ceramic to metal seals) can be formed. Sputtered and ion plated film characteristics such as the degree of adherence, coherence and morphological growth which contribute to film performance and reliability are described and illustrated as used in practice. It is concluded that the potential future of sputtered and ion plated films for industrial applications will depend primarily upon greater comprehension of materials selection, possible elimination of restrictions for coating/substrate combinations and the awareness of utilizing the proper deposition parameters.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siekhaus, W. J.; Teslich, N. E.; Weber, P. K.

Depleted uranium that included carbide inclusions was sputtered with 30-keV gallium ions or 16-kev cesium ions to depths much greater than the ions’ range, i.e. using steady-state sputtering. The recession of both the uranium’s and uranium carbide’s surfaces and the ion corresponding fluences were used to determine the steady-state target sputtering yields of both uranium and uranium carbide, i.e. 6.3 atoms of uranium and 2.4 units of uranium carbide eroded per gallium ion, and 9.9 uranium atoms and 3.65 units of uranium carbide eroded by cesium ions. The steady state surface composition resulting from the simultaneous gallium or cesium implantationmore » and sputter-erosion of uranium and uranium carbide were calculated to be U₈₆Ga₁₄, (UC)₇₀Ga₃₀ and U₈₁Cs₉, (UC)₇₉Cs₂₁, respectively.« less

Ion Acceleration by Double Layers with Multi-Component Ion Species

NASA Astrophysics Data System (ADS)

Good, Timothy; Aguirre, Evan; Scime, Earl; West Virginia University Team

2017-10-01

Current-free double layers (CFDL) models have been proposed to explain observations of magnetic field-aligned ion acceleration in plasmas expanding into divergent magnetic field regions. More recently, experimental studies of the Bohm sheath criterion in multiple ion species plasma reveal an equilibration of Bohm speeds at the sheath-presheath boundary for a grounded plate in a multipole-confined filament discharge. We aim to test this ion velocity effect for CFDL acceleration. We report high resolution ion velocity distribution function (IVDF) measurements using laser induced fluorescence downstream of a CFDL in a helicon plasma. Combinations of argon-helium, argon-krypton, and argon-xenon gases are ionized and measurements of argon or xenon IVDFs are investigated to determine whether ion acceleration is enhanced (or diminished) by the presence of lighter (or heavier) ions in the mix. We find that the predominant effect is a reduction of ion acceleration consistent with increased drag arising from increased gas pressure under all conditions, including constant total gas pressure, equal plasma densities of different ions, and very different plasma densities of different ions. These results suggest that the physics responsible for acceleration of multiple ion species in simple sheaths is not responsible for the ion acceleration observed in these expanding plasmas. Department of Physics, Gettysburg College.

The effect of plasma impurities on the sputtering of tungsten carbide

NASA Astrophysics Data System (ADS)

Vörtler, K.; Björkas, C.; Nordlund, K.

2011-03-01

Understanding of sputtering by ion bombardment is needed in a wide range of applications. In fusion reactors, ion impacts originating from a hydrogen-isotope-rich plasma will lead, among other effects, to sputtering of the wall material. To study the effect of plasma impurities on the sputtering of the wall mixed material tungsten carbide molecular dynamics simulations were carried out. Simulations of cumulative D cobombardment with C, W, He, Ne or Ar impurities on crystalline tungsten carbide were performed in the energy range 100-300 eV. The sputtering yields obtained at low fluences were compared to steady state SDTrimSP yields. During bombardment single C atom sputtering was preferentially observed. We also detected significant WxCy molecule sputtering. We found that this molecule sputtering mechanism is of physical origin.

Nanopatterning of optical surfaces during low-energy ion beam sputtering

NASA Astrophysics Data System (ADS)

Liao, Wenlin; Dai, Yifan; Xie, Xuhui

2014-06-01

Ion beam figuring (IBF) provides a highly deterministic method for high-precision optical surface fabrication, whereas ion-induced microscopic morphology evolution would occur on surfaces. Consequently, the fabrication specification for surface smoothness must be seriously considered during the IBF process. In this work, low-energy ion nanopatterning of our frequently used optical material surfaces is investigated to discuss the manufacturability of an ultrasmooth surface. The research results indicate that ion beam sputtering (IBS) can directly smooth some amorphous or amorphizable material surfaces, such as fused silica, Si, and ULE under appropriate processing conditions. However, for IBS of a Zerodur surface, preferential sputtering together with curvature-dependent sputtering overcome ion-induced smoothing mechanisms, leading to the granular nanopatterns' formation and the coarsening of the surface. Furthermore, the material property difference at microscopic scales and the continuous impurity incorporation would affect the ion beam smoothing of optical surfaces. Overall, IBS can be used as a promising technique for ultrasmooth surface fabrication, which strongly depends on processing conditions and material characters.

Effects of surface condition on the work function and valence-band position of ZnSnN2

NASA Astrophysics Data System (ADS)

Shing, Amanda M.; Tolstova, Yulia; Lewis, Nathan S.; Atwater, Harry A.

2017-12-01

ZnSnN2 is an emerging wide band gap earth-abundant semiconductor with potential applications in photonic devices such as solar cells, LEDs, and optical sensors. We report the characterization by ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy of reactively radio-frequency sputtered II-IV-nitride ZnSnN2 thin films. For samples transferred in high vacuum, the ZnSnN2 surface work function was 4.0 ± 0.1 eV below the vacuum level, with a valence-band onset of 1.2 ± 0.1 eV below the Fermi level. The resulting band diagram indicates that the degenerate bulk Fermi level position in ZnSnN2 shifts to mid-gap at the surface due to band bending that results from equilibration with delocalized surface states within the gap. Brief (< 10 s) exposures to air, a nitrogen-plasma treatment, or argon-ion sputtering caused significant chemical changes at the surface, both in surface composition and interfacial energetics. The relative band positioning of the n-type semiconductor against standard redox potentials indicated that ZnSnN2 has an appropriate energy band alignment for use as a photoanode to effect the oxygen-evolution reaction.

Study of fission-product segregation in used CANDU fuel by X-ray photoelectron spectroscopy (XPS) II

NASA Astrophysics Data System (ADS)

Hocking, William H.; Duclos, A. Michael; Johnson, Lawrence H.

1994-03-01

A thorough investigation of the grain-boundary chemistry of used CANDU fuel from one intact element has been conducted by X-ray photoelectron spectroscopy (XPS). Selected findings from more extensive XPS measurements on other used CANDU fuels exposed to storage conditions are included for comparison. Cesium, rubidium, tellurium and barium have been commonly observed, often reaching high degrees of surface enrichment, although their relative abundances can vary widely with a complex dependence on the fuel irradiation history. Lower concentrations of cadmium, molybdenum, strontium and iodine have also been occasionally detected. Except for iodine, chemical-shift data are indicative of oxidized species, possibly uranates. Segregation at monolayer-level coverages has been demonstrated by sequential XPS analysis and argon-ion sputtering. Calculations based on an idealized thin-film model are consistent with the depth profiles. The interpretation of these results is discussed in the context of previous studies, especially on LWR fuels.

Initial stages of microbiologically influenced tarnishing on titanium after 20 months of immersion in freshwater.

PubMed

Moreno, D A; Cano, E; Ibars, J R; Polo, J L; Montero, F; Bastidas, J M

2004-05-01

This paper studies the initial stages of iridescent tarnishes on titanium heat exchanger tubes in contact with running freshwater on the river Tagus in Spain for up to 20 months. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy [(SEM with energy dispersive X-ray (EDX)] and X-ray photoelectron spectroscopy (XPS) in conjunction with argon-ion sputtering were the techniques used. The EIS data indicated a capacitive behavior, showing a semicircle that was better defined as the experimental time increased, indicating a decreasing tarnishing resistance of titanium. XPS and EDX results indicated that the main elements identified were calcium, phosphorus, nitrogen, and iron. The amount of these elements was higher on the tarnished titanium specimens than on the untarnished specimens. SEM analysis showed the presence of diatoms in the iridescent tarnishes on titanium tubes. Copyright 2003 Springer-Verlag

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nazareth, A.S.; Sood, D.K.; Zmood, R.B.

A focusing grid broad beam Kaufman source, using argon ions on a target of nominal composition Nd{sub 2}Fe{sub 14}B has been employed to sputter deposit magnetic thin films of thicknesses ranging from 800 {angstrom} to 1300 {angstrom} on silicon-(111) substrates at room temperature. These films were characterized for their composition depth profile by Rutherford Backscattering Spectroscopy, while x-ray diffraction was used to study the crystallographic structure. Due to a close match between (111) Si with (220) Nd{sub 2}Fe{sub 14}B lattice spacings, preferred crystallographic texturing was expected, and experimental results showed a greatly enhanced (220) texture. The degradation in magnetic propertiesmore » was attributed to the presence of oxygen in the films as indicated by concentration depth profiles. It is premised that another significant role of oxygen may be to relieve the misfit strain across the interface by its incorporation within the Nd{sub 2}Fe{sub 14}B phase.« less

Ion velocity distribution functions in argon and helium discharges: detailed comparison of numerical simulation results and experimental data

NASA Astrophysics Data System (ADS)

Wang, Huihui; Sukhomlinov, Vladimir S.; Kaganovich, Igor D.; Mustafaev, Alexander S.

2017-02-01

Using the Monte Carlo collision method, we have performed simulations of ion velocity distribution functions (IVDF) taking into account both elastic collisions and charge exchange collisions of ions with atoms in uniform electric fields for argon and helium background gases. The simulation results are verified by comparison with the experiment data of the ion mobilities and the ion transverse diffusion coefficients in argon and helium. The recently published experimental data for the first seven coefficients of the Legendre polynomial expansion of the ion energy and angular distribution functions are used to validate simulation results for IVDF. Good agreement between measured and simulated IVDFs shows that the developed simulation model can be used for accurate calculations of IVDFs.

Coarsening of ion-beam-induced surface ripple in Si: Nonlinear effect vs. geometrical shadowing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datta, Debi Prasad; Chini, Tapas Kumar

The temporal evolution of a periodic ripple pattern on a silicon surface undergoing erosion by 30 keV argon ion bombardment has been studied for two angles of ion incidence of 60 deg. and 70 deg. using ex situ atomic force microscopy (AFM) in ambient condition. The roughness amplitude (w) grows exponentially with sputtering time for both the angle of ion incidence followed by a slow growth process that saturates eventually with almost constant amplitude. Within the exponential growth regime of amplitude, however, ripple wavelength (l) remains constant initially and increases subsequently as a power law fashion l{proportional_to}t{sup n}, where n=0.47{+-}0.02more » for a 60 deg. angle of ion incidence followed by a saturation. Wavelength coarsening was also observed for 70 deg. but ordering in the periodic ripple pattern is destroyed quickly for 70 deg. as compared to 60 deg. . The ripple orientation, average ripple wavelength at the initial stage of ripple evolution, and the exponential growth of ripple amplitude can be described by a linear continuum model. While the wavelength coarsening could possibly be explained in the light of recent hydrodynamic model based continuum theory, the subsequent saturation of wavelength and amplitude was attributed to the effect of geometrical shadowing. This is an experimental result that probably gives a hint about the upper limit of the energy of ion beam rippling for applying the recently developed type of nonlinear continuum model.« less

Ion beam sputter modification of the surface morphology of biological implants

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Banks, B. A.

1976-01-01

The surface chemistry and texture of materials used for biological implants may significantly influence their performance and biocompatibility. Recent interest in the microscopic control of implant surface texture has led to the evaluation of ion beam sputtering as a potentially useful surface roughening technique. Ion sources, similar to electron bombardment ion thrusters designed for propulsive applications, are used to roughen the surfaces of various biocompatible alloys or polymer materials. These materials are typically used for dental implants, orthopedic prostheses, vascular prostheses, and artificial heart components. Masking techniques and resulting surface textures are described along with progress concerning evaluation of the biological response to the ion beam sputtered surfaces.

Ion-beam-sputter modification of the surface morphology of biological implants

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Banks, B. A.

1977-01-01

The surface chemistry and texture of materials used for biological implants may significantly influence their performance and biocompatibility. Recent interest in the microscopic control of implant surface texture has led to the evaluation of ion-beam sputtering as a potentially useful surface roughening technique. Ion sources, similar to electron-bombardment ion thrusters designed for propulsive applications, are used to roughen the surfaces of various biocompatible alloys or polymer materials. These materials are typically used for dental implants, orthopedic prostheses, vascular prostheses, and artificial heart components. Masking techniques and resulting surface textures are described along with progress concerning evaluation of the biological response to the ion-beam-sputtered surfaces.

Dynamics of nanoparticle morphology under low energy ion irradiation.

PubMed

Holland-Moritz, Henry; Graupner, Julia; Möller, Wolfhard; Pacholski, Claudia; Ronning, Carsten

2018-08-03

If nanostructures are irradiated with energetic ions, the mechanism of sputtering becomes important when the ion range matches about the size of the nanoparticle. Gold nanoparticles with diameters of ∼50 nm on top of silicon substrates with a native oxide layer were irradiated by gallium ions with energies ranging from 1 to 30 keV in a focused ion beam system. High resolution in situ scanning electron microscopy imaging permits detailed insights in the dynamics of the morphology change and sputter yield. Compared to bulk-like structures or thin films, a pronounced shaping and enhanced sputtering in the nanostructures occurs, which enables a specific shaping of these structures using ion beams. This effect depends on the ratio of nanoparticle size and ion energy. In the investigated energy regime, the sputter yield increases at increasing ion energy and shows a distinct dependence on the nanoparticle size. The experimental findings are directly compared to Monte Carlo simulations obtained from iradina and TRI3DYN, where the latter takes into account dynamic morphological and compositional changes of the target.

RADIATION CHEMISTRY OF HIGH ENERGY CARBON, NEON AND ARGON IONS: INTEGRAL YIELDS FROM FERROUS SULFATE SOLUTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christman, E.A.; Appleby, A.; Jayko, M.

1980-07-01

Chemical yields of Fe{sup 3+} have been measured from FeSO{sub 4} solutions irradiated in the presence and absence of oxygen with carbon, neon, and argon ions from the Berkeley Bevalac facility. G(Fe{sup 3+}) decreases with increasing beam penetration and with increasing atomic number of the incident ion. The results are compared with current theoretical expectations of the behavior of these particles in an aqueous absorber. The chemical yields are consistently higher than theoretically predicted, by amounts varying from <6.2% (carbon ions) to <13.2% (argon ions). The additional yields are possibly attributable to fragmentation of the primary particle beams.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudeck, P.J.; Harper, J.M.E.; Fryer, P.M.

The copper concentration in aluminum-copper alloys can be altered by ion bombardment during film deposition. We have measured the sputtering yields of aluminum and copper in Al-Cu alloys as a function of the Cu concentration (5--13 at. %) and the angle of ion incidence (0/sup 0/--40/sup 0/ from normal). During deposition, the films were partially resputtered by 500 eV Ar/sup +/ ion bombardment from a Kaufman ion source. We found that the Cu sputtering yield decreases by up to a factor of 10 in the alloy, relative to elemental Cu. The Al sputtering yield remains close to the elemental value.more » The net effect is a strong preferential sputtering of Al relative to Cu, which enhances the Cu concentration in an ion-bombarded film. The Al/Cu sputtering yield ratio for normal incidence ion bombardment ranges from 3 to 5 as a function of Cu concentration. This ratio decreases with increasing angle of incidence to as low as 2 for 40/sup 0/ incident ions. However, since a higher fraction of the film is resputtered from a sloping surface, a higher Cu concentration is found on a sloping surface relative to a flat surface. These results show that the film composition will vary as a function of the surface topography.« less

ITO/InP solar cells: A comparison of devices fabricated by ion beam and RF sputtering of the ITO

NASA Technical Reports Server (NTRS)

Coutts, T. J.

1987-01-01

This work was performed with the view of elucidating the behavior of indium tin oxide/indium phosphide (ITO/InP) solar cells prepared by RF and ion beam sputtering. It was found that using RF sputter deposition of the ITO always leads to more efficient devices than ion beam sputter deposition. An important aspect of the former technique is the exposure of the single crystal p-InP substrates to a very low plasma power prior to deposition. Substrates treated in this manner have also been used for ion beam deposition of ITO. In this case the cells behave very similarly to the RF deposited cells, thus suggesting that the lower power plasma exposure (LPPE) is the crucial process step.

Sputtering phenomena in ion thrusters

NASA Technical Reports Server (NTRS)

Robinson, R. S.; Rossnagel, S. M.

1983-01-01

Sputtering effects in discharge chambers of ion thrusters are lifetime limiting in basically two ways: (1) ion bombardment of critical thruster components at energies sufficient to cause sputtering removes significant quantities of material; enough to degrade operation through adverse dimensional changes or possibly lead to complete component failure, and (2) metals sputtered from these intensely bombarded components are deposited in other locations as thin films and subsequently flake or peel off; the flakes then lodge elsewhere in the discharge chamber with the possibility of providing conductive paths for short circuiting of thruster components such as the ion optics. This experimental work has concentrated in two areas. The first has been to operate thrusters for multi-hour periods and to observe and measure the films found inside the thruster. The second was to simulate the environment inside the discharge chamber of the thruster by means of a dual ion beam system. Here, films were sputter deposited in the presence of a second low energy bombarding beam to simulate film deposition on thruster interior surfaces that undergo simultaneous sputtering and deposition. Mo presents serious problems for use in a thruster as far as film deposition is concerned. Mo films were found to be in high stress, making them more likely to peel and flake.

Metal-insulator-semiconductor capacitors with bismuth oxide as insulator

NASA Astrophysics Data System (ADS)

Raju, T. A.; Talwai, A. S.

1981-07-01

Metal-insulator-semiconductor capacitors using aluminum Bi2O3 and silicon have been studied for varactor applications. Reactively sputtered Bi2O3 films which under suitable proportions of oxygen and argon and had high resistivity suitable for device applications showed a dielectric constant of 25.

Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, S.; Greczynski, G.; Jensen, J.

2012-07-01

Ion mass spectrometry was used to investigate discharges formed during high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a graphite target in Ar and Ar/N{sub 2} ambient. Ion energy distribution functions (IEDFs) were recorded in time-averaged and time-resolved mode for Ar{sup +}, C{sup +}, N{sub 2}{sup +}, N{sup +}, and C{sub x}N{sub y}{sup +} ions. An increase of N{sub 2} in the sputter gas (keeping the deposition pressure, pulse width, pulse frequency, and pulse energy constant) results for the HiPIMS discharge in a significant increase in C{sup +}, N{sup +}, and CN{sup +} ion energies.more » Ar{sup +}, N{sub 2}{sup +}, and C{sub 2}N{sup +} ion energies, in turn, did not considerably vary with the changes in working gas composition. The HiPIMS process showed higher ion energies and fluxes, particularly for C{sup +} ions, compared to DCMS. The time evolution of the plasma species was analyzed for HiPIMS and revealed the sequential arrival of working gas ions, ions ejected from the target, and later during the pulse-on time molecular ions, in particular CN{sup +} and C{sub 2}N{sup +}. The formation of fullerene-like structured CN{sub x} thin films for both modes of magnetron sputtering is explained by ion mass-spectrometry results and demonstrated by transmission electron microscopy as well as diffraction.« less

The characteristics of a new negative metal ion beam source and its applications

NASA Astrophysics Data System (ADS)

Paik, Namwoong

2001-10-01

Numerous efforts at energetic thin film deposition processes using ion beams have been made to meet the demands of today's thin film industry. As one of these efforts, a new Magnetron Sputter Negative Ion Source (MSNIS) was developed. In this study, the development and the characterization of the MSNIS were investigated. Amorphous carbon films were used as a sample coating medium to evaluate the ion beam energy effect. A review of energetic Physical Vapor Deposition (PVD) techniques is presented in Chapter 1. The energetic PVD methods can be classified into two major categories: the indirect ion beam method Ion Beam Assisted Deposition (IBAD), and the direct ion beam method-Direct Ion Beam Deposition (DIBD). In this chapter, currently available DIBD processes such as Cathodic Arc, Laser Ablation, Ionized Physical Vapor Deposition (I-PVD) and Magnetron Sputter Negative Ion Source (MSNIS) are individually reviewed. The design and construction of the MSNIS is presented in chapter 2. The MSNIS is a hybrid of the conventional magnetron sputter configuration and the cesium surface ionizer. The negative sputtered ions are produced directly from the sputter target by surface ionization. In chapter 3, the ion beam and plasma characteristics of an 8″ diameter MSNIS are investigated using a retarding field analyzer and a cylindrical Langmuir Probe. The measured electron temperature is approximately 2-5 eV, while the plasma density and plasma potential were of the order of 10 11-1012 cm3 and 5-20 V, respectively, depending on the pressure and power. In chapter 4, in order to evaluate the effect of the ion beam on the resultant films, amorphous carbon films were deposited under various conditions. The structure of carbon films was investigated using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The result suggests the fraction of spa bonding is more than 70% in some samples prepared by MSNIS while magnetron sputtered samples showed less than 30%. (Abstract shortened by UMI.)

Method for sputtering with low frequency alternating current

DOEpatents

Timberlake, John R.

1996-01-01

Low frequency alternating current sputtering is provided by connecting a low frequency alternating current source to a high voltage transformer having outer taps and a center tap for stepping up the voltage of the alternating current. The center tap of the transformer is connected to a vacuum vessel containing argon or helium gas. Target electrodes, in close proximity to each other, and containing material with which the substrates will be coated, are connected to the outer taps of the transformer. With an applied potential, the gas will ionize and sputtering from the target electrodes onto the substrate will then result. The target electrodes can be copper or boron, and the substrate can be stainless steel, aluminum, or titanium. Copper coatings produced are used in place of nickel and/or copper striking.

Method for sputtering with low frequency alternating current

DOEpatents

Timberlake, J.R.

1996-04-30

Low frequency alternating current sputtering is provided by connecting a low frequency alternating current source to a high voltage transformer having outer taps and a center tap for stepping up the voltage of the alternating current. The center tap of the transformer is connected to a vacuum vessel containing argon or helium gas. Target electrodes, in close proximity to each other, and containing material with which the substrates will be coated, are connected to the outer taps of the transformer. With an applied potential, the gas will ionize and sputtering from the target electrodes onto the substrate will then result. The target electrodes can be copper or boron, and the substrate can be stainless steel, aluminum, or titanium. Copper coatings produced are used in place of nickel and/or copper striking. 6 figs.

Cleaning of HT-7 Tokamak Exposed First Mirrors by Radio Frequency Magnetron Sputtering Plasma

NASA Astrophysics Data System (ADS)

Yan, Rong; Chen, Junling; Chen, Longwei; Ding, Rui; Zhu, Dahuan

2014-12-01

The stainless steel (SS) first mirror pre-exposed in the deposition-dominated environment of the HT-7 tokamak was cleaned in the newly built radio frequency (RF) magnetron sputtering plasma device. The deposition layer on the FM surface formed during the exposure was successfully removed by argon plasma with a RF power of about 80 W and a gas pressure of 0.087 Pa for 30 min. The total reflectivity of the mirrors was recovered up to 90% in the wavelength range of 300-800 nm, while the diffuse reflectivity showed a little increase, which was attributed to the increase of surface roughness in sputtering, and residual contaminants. The FMs made from single crystal materials could help to achieve a desired recovery of specular reflectivity in the future.

Modeling Solar-Wind Heavy-Ions' Potential Sputtering of Lunar KREEP Surface

NASA Technical Reports Server (NTRS)

Barghouty, A. F.; Meyer, F. W.; Harris, R. P.; Adams, J. H., Jr.

2012-01-01

Recent laboratory data suggest that potential sputtering may be an important weathering mechanism that can affect the composition of both the lunar surface and its tenuous exosphere; its role and implications, however, remain unclear. Using a relatively simple kinetic model, we will demonstrate that solar-wind heavy ions induced sputtering of KREEP surfaces is critical in establishing the timescale of the overall solar-wind sputtering process of the lunar surface. We will also also show that potential sputtering leads to a more pronounced and significant differentiation between depleted and enriched surface elements. We briefly discuss the impacts of enhanced sputtering on the composition of the regolith and the exosphere, as well as of solar-wind sputtering as a source of hydrogen and water on the moon.

Plasma particle simulation of electrostatic ion thrusters

NASA Technical Reports Server (NTRS)

Peng, Xiaohang; Keefer, Dennis; Ruyten, Wilhelmus

1990-01-01

Charge exchange collisons between beam ions and neutral propellant gas can result in erosion of the accelerator grid surfaces of an ion engine. A particle in cell (PIC) is developed along with a Monte Carlo method to simulate the ion dynamics and charge exchange processes in the grid region of an ion thruster. The simulation is two-dimensional axisymmetric and uses three velocity components (2d3v) to investigate the influence of charge exchange collisions on the ion sputtering of the accelerator grid surfaces. An example calculation has been performed for an ion thruster operated on xenon propellant. The simulation shows that the greatest sputtering occurs on the downstream surface of the grid, but some sputtering can also occur on the upstream surface as well as on the interior of the grid aperture.

Molecular dynamics investigation of hexagonal boron nitride sputtering and sputtered particle characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Brandon D., E-mail: bradenis@umich.edu; Boyd, Iain D.

The sputtering of hexagonal boron nitride (h-BN) by impacts of energetic xenon ions is investigated using a molecular dynamics (MD) model. The model is implemented within an open-source MD framework that utilizes graphics processing units to accelerate its calculations, allowing the sputtering process to be studied in much greater detail than has been feasible in the past. Integrated sputter yields are computed over a range of ion energies from 20 eV to 300 eV, and incidence angles from 0° to 75°. Sputtering of boron is shown to occur at energies as low as 40 eV at normal incidence, and sputtering of nitrogen atmore » as low as 30 eV at normal incidence, suggesting a threshold energy between 20 eV and 40 eV. The sputter yields at 0° incidence are compared to existing experimental data and are shown to agree well over the range of ion energies investigated. The semi-empirical Bohdansky curve and an empirical exponential function are fit to the data at normal incidence, and the threshold energy for sputtering is calculated from the Bohdansky curve fit as 35 ± 2 eV. These results are shown to compare well with experimental observations that the threshold energy lies between 20 eV and 40 eV. It is demonstrated that h-BN sputters predominantly as atomic boron and diatomic nitrogen, and the velocity distribution function (VDF) of sputtered boron atoms is investigated. The calculated VDFs are found to reproduce the Sigmund-Thompson distribution predicted by Sigmund's linear cascade theory of sputtering. The average surface binding energy computed from Sigmund-Thompson curve fits is found to be 4.5 eV for ion energies of 100 eV and greater. This compares well to the value of 4.8 eV determined from independent experiments.« less

Direct wafer bonding of highly conductive GaSb/GaInAs and GaSb/GaInP heterojunctions prepared by argon-beam surface activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Predan, Felix, E-mail: felix.predan@ise.fraunhofer.de; Reinwand, Dirk; Cariou, Romain

The authors present a low-temperature wafer bonding process for the formation of electrically conductive n-GaSb/n-Ga{sub 0.79}In{sub 0.21}As and n-GaSb/n-Ga{sub 0.32}In{sub 0.68}P heterojunctions. The surfaces are deoxidized by sputter-etching with an argon-beam and bonded in ultrahigh vacuum. The sputtering behavior was investigated for each material, revealing a distinct selective sputtering characteristic for Ga{sub 0.32}In{sub 0.68}P. According to these findings, the settings for the bonding process were chosen. The mechanical and electrical properties of the wafer bonds were studied. Fully bonded 2 in. wafer pairs were found for both material combinations exhibiting high bond energies, which are comparable to the binding energiesmore » in the semiconductors. Furthermore, bond resistances below 5 mΩ cm{sup 2} could be reached, which are in the range of the lowest resistances that have been reported for wafer bonded heterojunctions. This speaks, together with the high bond energies, for a high amount of covalent bonds at the interfaces. These promising bond characteristics make the integration of antimonides with arsenides or phosphides by wafer bonding attractive for various optoelectronic applications such as multijunction solar cells.« less

Theoretical investigation of the effect of hydrogen addition on the formation and properties of soliton in direct current argon plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saikia, P., E-mail: partha.008@gmail.com; Goswami, K. S.; Saikia, B. K.

2014-03-15

In this study the effect of hydrogen addition on the formation and properties of soliton in direct-current (DC) argon plasma is theoretically investigated. By coupling fluid equations with Poisons equation for such multi-component plasma, the Mach number and amplitude of the soliton are determined following pseudo potential method. Addition of hydrogen in argon discharge leads to the decrease of electron, Ar{sup +} ion density while a reverse trend was observed for ArH{sup +} and hydrogen like ions. It was found that presence of hydrogen like ions in argon plasma affects the formation of soliton with its amplitude significantly decreases asmore » concentration of hydrogen increases. On the other hand, increase in ion to electron temperature ratios of the lighter ions in the discharge also has a significant influence on the amplitude and formation of soliton. The inverse relation between solitons width and amplitude is found to be consistent for the entire range of study.« less

Lunar and Asteroid Composition Using a Remote Secondary Ion Mass Spectrometer

NASA Technical Reports Server (NTRS)

Elphic, R. C.; Funsten, H. O.; Barraclough, B. L.; Mccomas, D. J.; Nordholt, J. E.

1992-01-01

Laboratory experiments simulating solar wind sputtering of lunar surface materials have shown that solar wind protons sputter secondary ions in sufficient numbers to be measured from low-altitude lunar orbit. Secondary ions of Na, Mg, Al, Si, K, Ca, Mn, Ti, and Fe have been observed sputtered from sample simulants of mare and highland soils. While solar wind ions are hundreds of times less efficient than those used in standard secondary ion mass spectrometry, secondary ion fluxes expected at the Moon under normal solar wind conditions range from approximately 10 to greater than 10(exp 4) ions cm(sup -2)s(sup -1), depending on species. These secondary ion fluxes depend both on concentration in the soil and on probability of ionization; yields of easily ionized elements such as K and Na are relatively much greater than those for the more electronegative elements and compounds. Once these ions leave the surface, they are subject to acceleration by local electric and magnetic fields. For typical solar wind conditions, secondary ions can be accelerated to an orbital observing location. The same is true for atmospheric atoms and molecules that are photoionized by solar EUV. The instrument to detect, identify, and map secondary ions sputtered from the lunar surface and photoions arising from the tenuous atmosphere is discussed.

High-Power Ion Thruster Technology

NASA Technical Reports Server (NTRS)

Beattie, J. R.; Matossian, J. N.

1996-01-01

Performance data are presented for the NASA/Hughes 30-cm-diam 'common' thruster operated over the power range from 600 W to 4.6 kW. At the 4.6-kW power level, the thruster produces 172 mN of thrust at a specific impulse of just under 4000 s. Xenon pressure and temperature measurements are presented for a 6.4-mm-diam hollow cathode operated at emission currents ranging from 5 to 30 A and flow rates of 4 sccm and 8 sccm. Highly reproducible results show that the cathode temperature is a linear function of emission current, ranging from approx. 1000 C to 1150 C over this same current range. Laser-induced fluorescence (LIF) measurements obtained from a 30-cm-diam thruster are presented, suggesting that LIF could be a valuable diagnostic for real-time assessment of accelerator-arid erosion. Calibration results of laminar-thin-film (LTF) erosion badges with bulk molybdenum are presented for 300-eV xenon, krypton, and argon sputtering ions. Facility-pressure effects on the charge-exchange ion current collected by 8-cm-diam and 30-cm-diam thrusters operated on xenon propellant are presented to show that accel current is nearly independent of facility pressure at low pressures, but increases rapidly under high-background-pressure conditions.

Accelerated life test of sputtering and anode deposit spalling in a small mercury ion thruster

NASA Technical Reports Server (NTRS)

Power, J. L.

1975-01-01

Tantalum and molybdenum sputtered from discharge chamber components during operation of a 5 centimeter diameter mercury ion thruster adhered much more strongly to coarsely grit blasted anode surfaces than to standard surfaces. Spalling of the sputtered coating did occur from a coarse screen anode surface but only in flakes less than a mesh unit long. The results were obtained in a 200 hour accelerated life test conducted at an elevated discharge potential of 64.6 volts. The test approximately reproduced the major sputter erosion and deposition effects that occur under normal operation but at approximately 75 times the normal rate. No discharge chamber component suffered sufficient erosion in the test to threaten its structural integrity or further serviceability. The test indicated that the use of tantalum-surfaced discharge chamber components in conjunction with a fine wire screen anode surface should cure the problems of sputter erosion and sputtered deposits spalling in long term operation of small mercury ion thrusters.

Sputter deposition for multi-component thin films

DOEpatents

Krauss, A.R.; Auciello, O.

1990-05-08

Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams. 10 figs.

Sputter deposition for multi-component thin films

DOEpatents

Krauss, Alan R.; Auciello, Orlando

1990-01-01

Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams.

Waves generated in the vicinity of an argon plasma gun in the ionosphere

NASA Technical Reports Server (NTRS)

Cahill, L. J., Jr.; Arnoldy, R. L.; Lysak, R. L.; Peria, W.; Lynch, K. A.

1993-01-01

Wave and particle observations were made in the close vicinity of an argon plasma gun carned to over 600 km altitude on a sounding rocket. The gun was carned on a subpayload, separated from the main payload early in the flight. Twelve-second argon ion ejections were energized alternately with a peak energy of 100 or 200 eV. They produced waves, with multiple harmonics, in the range of ion cyclotron waves, 10 to 1000 Hz at rocket altitudes. Many of these waves could not be identified as corresponding to the cyclotron frequencies of any of the ions, argon or ambient, known to be present. In addition, the wave frequencies were observed to rise and fall and to change abruptly during a 12-s gun operation. The wave amplitudes, near a few hundred Hertz, were of the order of O. 1 V/m. Some of the waves may be ion-ion hybrid waves. Changes in ion populations were observed at the main payload and at the subpayload during gun operations. A gun-related, field-aligned, electron population also appeared.

Waves generated in the vicinity of an argon plasma gun in the ionosphere

NASA Astrophysics Data System (ADS)

Cahill, L. J., Jr.; Arnoldy, R. L.; Lysak, R. L.; Peria, W.; Lynch, K. A.

1993-06-01

Wave and particle observations were made in the close vicinity of an argon plasma gun carned to over 600 km altitude on a sounding rocket. The gun was carned on a subpayload, separated from the main payload early in the flight. Twelve-second argon ion ejections were energized alternately with a peak energy of 100 or 200 eV. They produced waves, with multiple harmonics, in the range of ion cyclotron waves, 10 to 1000 Hz at rocket altitudes. Many of these waves could not be identified as corresponding to the cyclotron frequencies of any of the ions, argon or ambient, known to be present. In addition, the wave frequencies were observed to rise and fall and to change abruptly during a 12-s gun operation. The wave amplitudes, near a few hundred Hertz, were of the order of O. 1 V/m. Some of the waves may be ion-ion hybrid waves. Changes in ion populations were observed at the main payload and at the subpayload during gun operations. A gun-related, field-aligned, electron population also appeared.

Systematic investigations of low energy Ar ion beam sputtering of Si and Ag

NASA Astrophysics Data System (ADS)

Feder, R.; Frost, F.; Neumann, H.; Bundesmann, C.; Rauschenbach, B.

2013-12-01

Ion beam sputter deposition (IBD) delivers some intrinsic features influencing the growing film properties, because ion properties and geometrical process conditions generate different energy and spatial distributions of the sputtered and scattered particles. Even though IBD has been used for decades, the full capabilities are not investigated systematically and specifically used yet. Therefore, a systematic and comprehensive analysis of the correlation between the properties of the ion beam, the generated secondary particles and backscattered ions and the deposited films needs to be done.A vacuum deposition chamber has been set up which allows ion beam sputtering of different targets under variation of geometrical parameters (ion incidence angle, position of substrates and analytics in respect to the target) and of ion beam parameters (ion species, ion energy) to perform a systematic and comprehensive analysis of the correlation between the properties of the ion beam, the properties of the sputtered and scattered particles, and the properties of the deposited films. A set of samples was prepared and characterized with respect to selected film properties, such as thickness and surface topography. The experiments indicate a systematic influence of the deposition parameters on the film properties as hypothesized before. Because of this influence, the energy distribution of secondary particles was measured using an energy-selective mass spectrometer. Among others, experiments revealed a high-energetic maximum for backscattered primary ions, which shifts with increasing emission angle to higher energies. Experimental data are compared with Monte Carlo simulations done with the well-known Transport and Range of Ions in Matter, Sputtering version (TRIM.SP) code [J.P. Biersack, W. Eckstein, Appl. Phys. A: Mater. Sci. Process. 34 (1984) 73]. The thicknesses of the films are in good agreement with those calculated from simulated particle fluxes. For the positions of the high-energetic maxima in the energy distribution of the backscattered primary ions, a deviation between simulated and measured data was found, most likely originating in a higher energy loss under experimental conditions than considered in the simulation.

Magnetospheric ion sputtering and water ice grain size at Europa

NASA Astrophysics Data System (ADS)

Cassidy, T. A.; Paranicas, C. P.; Shirley, J. H.; Dalton, J. B., III; Teolis, B. D.; Johnson, R. E.; Kamp, L.; Hendrix, A. R.

2013-03-01

We present the first calculation of Europa's sputtering (ion erosion) rate as a function of position on Europa's surface. We find a global sputtering rate of 2×1027 H2O s-1, some of which leaves the surface in the form of O2 and H2. The calculated O2 production rate is 1×1026 O2 s-1, H2 production is twice that value. The total sputtering rate (including all species) peaks at the trailing hemisphere apex and decreases to about 1/3rd of the peak value at the leading hemisphere apex. O2 and H2 sputtering, by contrast, is confined almost entirely to the trailing hemisphere. Most sputtering is done by energetic sulfur ions (100s of keV to MeV), but most of the O2 and H2 production is done by cold oxygen ions (temperature ∼ 100 eV, total energy ∼ 500 eV). As a part of the sputtering rate calculation we compared experimental sputtering yields with analytic estimates. We found that the experimental data are well approximated by the expressions of Famá et al. for ions with energies less than 100 keV (Famá, M., Shi, J., Baragiola, R.A., 2008. Sputtering of ice by low-energy ions. Surf. Sci. 602, 156-161), while the expressions from Johnson et al. fit the data best at higher energies (Johnson, R.E., Burger, M.H., Cassidy, T.A., Leblanc, F., Marconi, M., Smyth, W.H., 2009. Composition and Detection of Europa's Sputter-Induced Atmosphere, in: Pappalardo, R.T., McKinnon, W.B., Khurana, K.K. (Eds.), Europa. University of Arizona Press, Tucson.). We compare the calculated sputtering rate with estimates of water ice regolith grain size as estimated from Galileo Near-Infrared Mapping Spectrometer (NIMS) data, and find that they are strongly correlated as previously suggested by Clark et al. (Clark, R.N., Fanale, F.P., Zent, A.P., 1983. Frost grain size metamorphism: Implications for remote sensing of planetary surfaces. Icarus 56, 233-245.). The mechanism responsible for the sputtering rate/grain size link is uncertain. We also report a surface composition estimate using NIMS data from an area on the trailing hemisphere apex. We find a high abundance of sulfuric acid hydrate and radiation-resistant hydrated salts along with large water ice regolith grains, all of which are consistent with the high levels of magnetospheric bombardment at the trailing apex.

Ion-Deposited Polished Coatings

NASA Technical Reports Server (NTRS)

Banks, B. A.

1986-01-01

Polished, dense, adherent coatings relatively free of imperfections. New process consists of using broad-beam ion source in evacuated chamber to ion-clean rotating surface that allows grazing incidence of ion beam. This sputter cleans off absorbed gases, organic contaminants, and oxides of mirror surface. In addition to cleaning, surface protrusions sputter-etched away. Process particularly adaptable to polishing of various substrates for optical or esthetic purposes.

Sputtering from a Porous Material by Penetrating Ions

NASA Technical Reports Server (NTRS)

Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Johnson, R. E.; Caro, A.; Fama, M.; Loeffler, M.; Baragiola, R. A.; Farkas, D.

2012-01-01

Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space, Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

Investigation of the refractive index repeatability for tantalum pentoxide coatings, prepared by physical vapor film deposition techniques.

PubMed

Stenzel, O; Wilbrandt, S; Wolf, J; Schürmann, M; Kaiser, N; Ristau, D; Ehlers, H; Carstens, F; Schippel, S; Mechold, L; Rauhut, R; Kennedy, M; Bischoff, M; Nowitzki, T; Zöller, A; Hagedorn, H; Reus, H; Hegemann, T; Starke, K; Harhausen, J; Foest, R; Schumacher, J

2017-02-01

Random effects in the repeatability of refractive index and absorption edge position of tantalum pentoxide layers prepared by plasma-ion-assisted electron-beam evaporation, ion beam sputtering, and magnetron sputtering are investigated and quantified. Standard deviations in refractive index between 4*10^-4 and 4*10^-3 have been obtained. Here, lowest standard deviations in refractive index close to our detection threshold could be achieved by both ion beam sputtering and plasma-ion-assisted deposition. In relation to the corresponding mean values, the standard deviations in band-edge position and refractive index are of similar order.

Advances in sputtered and ion plated solid film lubrication

NASA Technical Reports Server (NTRS)

Spalvins, T.

1985-01-01

The glow discharge or ion assisted vacuum deposition techniques, primarily sputtering and ion plating, have rapidly emerged and offer great potential to deposit solid lubricants. The increased energizing of these deposition processes lead to improved adherence and coherence, favorable morphological growth, higher density, and reduced residual stresses in the film. These techniques are of invaluable importance where high precision machines tribo-components require very thin, uniform lubricating films (0.2 m), which do not interface with component tolerances. The performance of sputtered MoS2 films and ion plated Au and Pb films are described in terms of film thickness, coefficient of friction, and wear lives.

Ion density evolution in a high-power sputtering discharge with bipolar pulsing

NASA Astrophysics Data System (ADS)

Britun, N.; Michiels, M.; Godfroid, T.; Snyders, R.

2018-06-01

Time evolution of sputtered metal ions in high power impulse magnetron sputtering (HiPIMS) discharge with a positive voltage pulse applied after a negative one (regime called "bipolar pulse HiPIMS"—BPH) is studied using 2-D density mapping. It is demonstrated that the ion propagation dynamics is mainly affected by the amplitude and duration of the positive pulse. Such effects as ion repulsion from the cathode and the ionization zone shrinkage due to electron drift towards the cathode are clearly observed during the positive pulse. The BPH mode also alters the film crystallographic structure, as observed from X-ray diffraction analysis.

The first laboratory measurements of sulfur ions sputtering water ice

NASA Astrophysics Data System (ADS)

Galli, André; Pommerol, Antoine; Vorburger, Audrey; Wurz, Peter; Tulej, Marek; Scheer, Jürgen; Thomas, Nicolas; Wieser, Martin; Barabash, Stas

2015-04-01

The upcoming JUpiter ICy moons Explorer mission to Europa, Ganymede, and Callisto has renewed the interest in the interaction of plasma with an icy surface. In particular, the surface release processes on which exosphere models of icy moons rely should be tested with realistic laboratory experiments. We therefore use an existing laboratory facility for space hardware calibration in vacuum to measure the sputtering of water ice due to hydrogen, oxygen, and sulfur ions at energies from 1 keV to 100 keV. Pressure and temperature are comparable to surface conditions encountered on Jupiter's icy moons. The sputter target is a 1cm deep layer of porous, salty water ice. Our results confirm theoretical predictions that the sputter yield from oxygen and sulfur ions should be similar. Thanks to the modular set-up of our experiment we can add further surface processes relevant for icy moons, such as electron sputtering, sublimation, and photodesorption due to UV light.

Ion beam microtexturing of surfaces

NASA Technical Reports Server (NTRS)

Robinson, R. S.

1981-01-01

Some recent work in surface microtecturing by ion beam sputtering is described. The texturing is accomplished by deposition of an impurity onto a substrate while simultaneously bombarding it with an ion beam. A summary of the theory regarding surface diffusion of impurities and the initiation of cone formation is provided. A detailed experimental study of the time-development of individual sputter cones is described. A quasi-liquid coating was observed that apparently reduces the sputter rate of the body of a cone compared to the bulk material. Experimental measurements of surface diffusion activation energies are presented for a variety of substrate-seed combinations and range from about 0.3 eV to 1.2 eV. Observations of apparent crystal structure in sputter cones are discussed. Measurements of the critical temperature for cone formation are also given along with a correlation of critical temperature with substrate sputter rate.

Deposition of reactively ion beam sputtered silicon nitride coatings

NASA Technical Reports Server (NTRS)

Grill, A.

1982-01-01

An ion beam source was used to deposit silicon nitride films by reactively sputtering a silicon target with beams of Ar + N2 mixtures. The nitrogen fraction in the sputtering gas was 0.05 to 0.80 at a total pressure of 6 to 2 millionth torr. The ion beam current was 50 mA at 500 V. The composition of the deposited films was investigated by auger electron spectroscopy and the rate of deposition was determined by interferometry. A relatively low rate of deposition of about 2 nm. one-tenth min. was found. AES spectra of films obtained with nitrogen fractions higher than 0.50 were consistent with a silicon to nitrogen ratio corresponding to Si3N4. However the AES spectra also indicated that the sputtered silicon nitride films were contaminated with oxygen and carbon and contained significant amounts of iron, nickel, and chromium, most probably sputtered from the holder of the substrate and target.

Ejection of sodium from sodium sulfide by the sputtering of the surface of Io

NASA Technical Reports Server (NTRS)

Chrisey, D. B.; Johnson, R. E.; Boring, J. W.; Phipps, J. A.

1988-01-01

The mechanism by which Na is removed from the surface of Io prior to its injection into the plasma torus is investigated experimentally. Na2S films of thickness 3-8 microns were produced by spray coating an Ni substrate in a dry N2 atmosphere and subjected to sputtering by 34-keV Ar(+), Ne(+), Kr(+), or Xe(+) ions up to total doses of about 5 x 10 to the 18th ions/sq cm. The sputtering yields and mass spectra are found to be consistent with ejection of only small amounts of atomic Na and somewhat larger amounts of Na-containing molecules. It is concluded that the amount of Na ejected by magnetospheric-ion sputtering of Na2S would be insufficient to account for the amounts observed in the Io neutral cloud. A scenario involving sputtering of larger polysulfide molecules is considered.

Swift heavy-ions induced sputtering in BaF2 thin films

NASA Astrophysics Data System (ADS)

Pandey, Ratnesh K.; Kumar, Manvendra; Singh, Udai B.; Khan, Saif A.; Avasthi, D. K.; Pandey, Avinash C.

2013-11-01

In our present experiment a series of barium fluoride thin films of different thicknesses have been deposited by electron beam evaporation technique at room temperature on silicon substrates. The effect of film thickness on the electronic sputter yield of polycrystalline BaF2 thin films has been reported in the present work. Power law for sputtered species collected on catcher grids has also been reported for film of lowest thickness. Sputtering has been performed by 100 MeV Au+28 ions. Atomic force microscopy (AFM) has been done to check the surface morphology of pristine samples. Glancing angle X-ray diffraction (GAXRD) measurements show that the pristine films are polycrystalline in nature and the grain size increases with increase in film thickness. Rutherford backscattering spectrometry (RBS) of pristine as well as irradiated films was done to determine the areal concentration of Ba and F atoms in the films. A reduction in the sputter yield of BaF2 films with the increase in film thickness has been observed from RBS results. The thickness dependence sputtering is explained on the basis of thermal spike and the energy confinement of the ions in the smaller grains. Also transmission electron microscopy (TEM) of the catchers shows a size distribution of sputtered species with values of power law exponent 1/2 and 3/2 for two fluences 5 × 1011 and 1 × 1012 ions/cm2, respectively.

The effect of Argon pressure dependent V thin film on the phase transition process of (020) VO2 thin film

NASA Astrophysics Data System (ADS)

Meng, Yifan; Huang, Kang; Tang, Zhou; Xu, Xiaofeng; Tan, Zhiyong; Liu, Qian; Wang, Chunrui; Wu, Binhe; Wang, Chang; Cao, Juncheng

2018-01-01

It has been proved challenging to fabricate the single crystal orientation of VO2 thin film by a simple method. Based on chemical reaction thermodynamic and crystallization analysis theory, combined with our experimental results, we find out that when stoichiometric number of metallic V in the chemical equation is the same, the ratio of metallic V thin film surface average roughness Ra to thin film average particle diameter d decreases with the decreasing sputtering Argon pressure. Meanwhile, the oxidation reaction equilibrium constant K also decreases, which will lead to the increases of oxidation time, thereby the crystal orientation of the VO2 thin film will also become more uniform. By sputtering oxidation coupling method, metallic V thin film is deposited on c-sapphire substrate at 1 × 10-1 Pa, and then oxidized in the air with the maximum oxidation time of 65s, high oriented (020) VO2 thin film has been fabricated successfully, which exhibits ∼4.6 orders sheet resistance change across the metal-insulator transition.

Determining the sputter yields of molybdenum in low-index crystal planes via electron backscattered diffraction, focused ion beam and atomic force microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, H.S., E-mail: 160184@mail.csc.com.tw; Chiu, C.H.; Hong, I.T.

2013-09-15

Previous literature has used several monocrystalline sputtering targets with various crystalline planes, respectively, to investigate the variations of the sputter yield of materials in different crystalline orientations. This study presents a method to measure the sputtered yields of Mo for the three low-index planes (100), (110), and (111), through using an easily made polycrystalline target. The procedure was firstly to use electron backscattered diffraction to identify the grain positions of the three crystalline planes, and then use a focused ion beam to perform the micro-milling of each identified grain, and finally the sputter yields were calculated from the removed volumes,more » which were measured by atomic force microscope. Experimental results showed that the sputter yield of the primary orientations for Mo varied as Y{sub (110)} > Y{sub (100)} > Y{sub (111)}, coincidental with the ranking of their planar atomic packing densities. The concept of transparency of ion in the crystalline substance was applied to elucidate these results. In addition, the result of (110) orientation exhibiting higher sputter yield is helpful for us to develop a Mo target with a higher deposition rate for use in industry. By changing the deformation process from straight rolling to cross rolling, the (110) texture intensity of the Mo target was significantly improved, and thus enhanced the deposition rate. - Highlights: • We used EBSD, FIB and AFM to measure the sputter yields of Mo in low-index planes. • The sputter yield of the primary orientations for Mo varied as Y{sub (110)} > Y{sub (100)} > Y{sub (111)}. • The transparency of ion was used to elucidate the differences in the sputter yield. • We improved the sputter rate of polycrystalline Mo target by adjusting its texture.« less

Sputtering of Metals by Mass-Analyzed N2(+) and N(+)

NASA Technical Reports Server (NTRS)

Bader, Michel; Witteborn, Fred C.; Snouse, Thomas W.

1961-01-01

Low-energy sputtering studies were conducted with the help of a specially designed ion accelerator. A high-intensity rf ion source was developed for use in conjunction with electrostatic acceleration and magnetic mass separation of ion beams in the 0 to 8 kev energy range. Beams of N(+) or N2(+) ions have been produced with intensities of 200 to 500 micro-a (approx. 1 sq cm in cross section) and energy half-widths of about 20 ev. The sputtering yields of five metals (Cu, Ni, Fe, Mo, and W) were obtained as a function of energy (0-8 kev), bombarding ion (N(+) and N2(+)), and angle of incidence (normal and 450). Results are presented and some of their theoretical implications are discussed.

Electric properties of nanostructure (FeCoZr)x(CaF2)(100-x) produced in argon Ar atmosphere

NASA Astrophysics Data System (ADS)

Bondariev, Vitalii; Czarnacka, Karolina; Boiko, Oleksandr

2015-09-01

The paper presents frequency f and temperature Tp dependences of conductivity σ, capacitance Cp and phase shift angle θ for the nanocomposite metal-dielectric (FeCoZr)x(CaF2)(100-x). Samples of nanocomposite were produced by ion-beam sputtering in pure argon Ar atmosphere. Partial pressure of gas Ar in the ion source pAr=1.1×10-1Pa. Contains of metallic phase in tested sample is x = 54.6 at.%. Studies carried out by stand to measuring of AC electrical properties of nanocomposites and semiconductors. The measurements have been performed using alternating current within the frequency range of 50 Hz - 1 MHz for measuring temperatures ranging from 77 K to 373 K. On the frequency-temperature dependence of phase shift angle θ at low frequencies phase shift have capacitive character and at high frequencies - inductive. Position of fmin on the frequency dependence on capacitance Cp corresponds exactly to the resonance frequency fR for which the angle θ crosses zero. Analysis of the results showed that phenomena similar to phenomena in conventional circuit RLC occur in the nanocomposite (CoFeZr)54.6(CaF2)45.4. Jumping recharging between the defects leads to the formation of dipoles and consequently to the increase of permittivity. After a time τ electron returns to the first defect and dipole disappears. The formation of inductance in nanocomposite is associated with return jumps of electrons from defect with negative charge to the defect with positive charge, set by the time, which are characterized by low values of activation energy.

Energetic ion bombardment of Ag surfaces by C60+ and Ga+ projectiles.

PubMed

Sun, Shixin; Szakal, Christopher; Winograd, Nicholas; Wucher, Andreas

2005-10-01

The ion bombardment-induced release of particles from a metal surface is investigated using energetic fullerene cluster ions as projectiles. The total sputter yield as well as partial yields of neutral and charged monomers and clusters leaving the surface are measured and compared with corresponding data obtained with atomic projectile ions of similar impact kinetic energy. It is found that all yields are enhanced by about one order of magnitude under bombardment with the C60+ cluster projectiles compared with Ga+ ions. In contrast, the electronic excitation processes determining the secondary ion formation probability are unaffected. The kinetic energy spectra of sputtered particles exhibit characteristic differences which reflect the largely different nature of the sputtering process for both types of projectiles. In particular, it is found that under C60+ impact (1) the energy spectrum of sputtered atoms peaks at significantly lower kinetic energies than for Ga+ bombardment and (2) the velocity spectra of monomers and dimers are virtually identical, a finding which is in pronounced contrast to all published data obtained for atomic projectiles. The experimental findings are in reasonable agreement with recent molecular dynamics simulations.

Experimental and simulation-based investigation of He, Ne and Ar irradiation of polymers for ion microscopy

PubMed Central

Rzeznik, Lukasz; Fleming, Yves; Wirtz, Tom

2016-01-01

Summary Secondary ion mass spectrometry (SIMS) on the helium ion microscope (HIM) promises higher lateral resolution than on classical SIMS instruments. However, full advantage of this new technique can only be obtained when the interaction of He+ or Ne+ primary ions with the sample is fully controlled. In this work we investigate how He+ and Ne+ bombardment influences roughness formation and preferential sputtering for polymer samples and how they compare to Ar+ primary ions used in classical SIMS by combining experimental techniques with Molecular Dynamics (MD) simulations and SD_TRIM_SP modelling. The results show that diffusion coefficients for He, Ne and Ar in polymers are sufficiently high to prevent any accumulation of rare gas atoms in the polymers which could lead to some swelling and bubble formation. Roughness formation was also not observed. Preferential sputtering is more of a problem, with enrichment of carbon up to surface concentrations above 80%. In general, the preferential sputtering is largely depending on the primary ion species and the impact energies. For He+ bombardment, it is more of an issue for low keV impact energies and for the heavier primary ion species the preferential sputtering is sample dependent. For He+ steady state conditions are reached for fluences much higher than 1018 ions/cm2. For Ne+ and Ar+, the transient regime extends up to fluences of 1017–1018 ions/cm2. Hence, preferential sputtering needs to be taken into account when interpreting images recorded under He+ or Ne+ bombardment on the HIM. PMID:27547629

The effects of argon ion bombardment on the corrosion resistance of tantalum

NASA Astrophysics Data System (ADS)

Ramezani, A. H.; Sari, A. H.; Shokouhy, A.

2017-02-01

Application of ion beam has been widely used as a surface modification method to improve surface properties. This paper investigates the effect of argon ion implantation on surface structure as well as resistance against tantalum corrosion. In this experiment, argon ions with energy of 30 keV and in doses of 1 × 1017-10 × 1017 ions/cm2 were used. The surface bombardment with inert gases mainly produces modified topography and morphology of the surface. Atomic Force Microscopy was also used to patterned the roughness variations prior to and after the implantation phase. Additionally, the corrosion investigation apparatus wear was applied to compare resistance against tantalum corrosion both before and after ion implantation. The results show that argon ion implantation has a substantial impact on increasing resistance against tantalum corrosion. After the corrosion test, scanning electron microscopy (SEM) analyzed the samples' surface morphologies. In addition, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. The purpose of this paper was to obtain the perfect condition for the formation of tantalum corrosion resistance. In order to evaluate the effect of the ion implantation on the corrosion behavior, potentiodynamic tests were performed. The results show that the corrosion resistance of the samples strongly depends on the implantation doses.

Carbon atom and cluster sputtering under low-energy noble gas plasma bombardment

NASA Astrophysics Data System (ADS)

Oyarzabal, E.; Doerner, R. P.; Shimada, M.; Tynan, G. R.

2008-08-01

Exit-angle resolved carbon atom and cluster (C2 and C3) sputtering yields are measured during different noble gas (Xe, Kr, Ar, Ne, and He) ion bombardments from a plasma, for low incident energies (75-225 eV). A quadrupole mass spectrometer (QMS) is used to detect the fraction of sputtered neutrals that is ionized in the plasma and to obtain the angular distribution by changing the angle between the target normal and the QMS aperture. A one-dimensional Monte Carlo code is used to simulate the interaction of the plasma and the sputtered particles in the region between the sample and the QMS. The effective elastic scattering cross sections of C, C2, and C3 with the different bombarding gas neutrals are obtained by varying the distance between the sample and the QMS and by performing a best fit of the simulation results to the experimental results. The total sputtering yield (C+C2+C3) for each bombarding gas is obtained from weight-loss measurements and the sputtering yield for C, C2, and C3 is then calculated from the integration of the measured angular distribution, taking into account the scattering and ionization of the sputtered particles between the sample and the QMS. We observe undercosine angular distributions of the sputtered atoms and clusters for all the studied bombarding gases and a clear decrease of the atom to cluster (C2 and C3) sputtering ratio as the incident ion mass increases, changing from a carbon atom preferential erosion for the lower incident ion masses (He, Ne, and Ar) to a cluster preferential erosion for the higher incident ion masses (Kr and Xe).

Molecular dynamics simulations with electronic stopping can reproduce experimental sputtering yields of metals impacted by large cluster ions

NASA Astrophysics Data System (ADS)

Tian, Jiting; Zhou, Wei; Feng, Qijie; Zheng, Jian

2018-03-01

An unsolved problem in research of sputtering from metals induced by energetic large cluster ions is that molecular dynamics (MD) simulations often produce sputtering yields much higher than experimental results. Different from the previous simulations considering only elastic atomic interactions (nuclear stopping), here we incorporate inelastic electrons-atoms interactions (electronic stopping, ES) into MD simulations using a friction model. In this way we have simulated continuous 45° impacts of 10-20 keV C60 on a Ag(111) surface, and found that the calculated sputtering yields can be very close to the experimental results when the model parameter is appropriately assigned. Conversely, when we ignore the effect of ES, the yields are much higher, just like the previous studies. We further expand our research to the sputtering of Au induced by continuous keV C60 or Ar100 bombardments, and obtain quite similar results. Our study indicates that the gap between the experimental and the simulated sputtering yields is probably induced by the ignorance of ES in the simulations, and that a careful treatment of this issue is important for simulations of cluster-ion-induced sputtering, especially for those aiming to compare with experiments.

Sputtering Holes with Ion Beamlets

NASA Technical Reports Server (NTRS)

Byers, D. C.; Banks, B. A.

1974-01-01

Ion beamlets of predetermined configurations are formed by shaped apertures in the screen grid of an ion thruster having a double grid accelerator system. A plate is placed downstream from the screen grid holes and attached to the accelerator grid. When the ion thruster is operated holes having the configuration of the beamlets formed by the screen grid are sputtered through the plate at the accelerator grid.

Gold-carbon composite thin films for electrochemical gas sensor prepared by reactive plasma sputtering

NASA Astrophysics Data System (ADS)

Okamoto, A.; Suzuki, Y.; Yoshitake, M.; Ogawa, S.; Nakano, N.

1997-01-01

We have investigated the properties of gold-carbon composite thin films prepared by a plasma sputtering deposition using argon and methane mixture gas. These composite films have an uneven surface in submicron scale or consist of nano-scale particles of gold polycrystalline. Such morphological properties can be controlled by the sputtering voltage and the partial pressure of methane gas. The working electrode of electrochemical gas sensor has needed a stable gas sensitivity and a good gas selectivity. Our composite film is one of the excellent candidates for a thin film working electrode of electrochemical gas sensor. It is described that the output current of sensor is related to the preparation conditions of the thin films and increase linearly as the concentration of PH 3 gas ranging from 0.1 to 1.0 ppm is increasing.

Sputtering of rough surfaces: a 3D simulation study

NASA Astrophysics Data System (ADS)

von Toussaint, U.; Mutzke, A.; Manhard, A.

2017-12-01

The lifetime of plasma-facing components is critical for future magnetic confinement fusion power plants. A key process limiting the lifetime of the first-wall is sputtering by energetic ions. To provide a consistent modeling of the sputtering process of realistic geometries, the SDTrimSP-code has been extended to enable the processing of analytic as well as measured arbitrary 3D surface morphologies. The code has been applied to study the effect of varying the impact angle of ions on rough surfaces on the sputter yield as well as the influence of the aspect ratio of surface structures on the 2D distribution of the local sputtering yields. Depending on the surface morphologies reductions of the effective sputter yields to less than 25% have been observed in the simulation results.

ICP-MS with hexapole collision cell for isotope ratio measurements of Ca, Fe, and Se.

PubMed

Boulyga, S F; Becker, J S

2001-07-01

To avoid mass interferences on analyte ions caused by argon ions and argon molecular ions via reactions with collision gases, an rf hexapole filled with helium and hydrogen has been used in inductively coupled plasma mass spectrometry (ICP-MS), and its performance has been studied. Up to tenfold improvement in sensitivity was observed for heavy elements (m > 100 u), because of better ion transmission through the hexapole ion guide. A reduction of argon ions Ar+ and the molecular ions of argon ArX+ (X = O, Ar) by up to three orders of magnitude was achieved in a hexapole collision cell of an ICP-MS ("Platform ICP", Micromass, Manchester, UK) as a result of gas-phase reactions with hydrogen when the hexapole bias (HB) was set to 0 V; at an HB of 1.6 V argon, and argon-based ions of masses 40 u, 56 u, and 80 u, were reduced by approximately four, two, and five orders of magnitude, respectively. The signal-to-noise ratio 80Se/ 40Ar2+ was improved by more than five orders of magnitude under optimized experimental conditions. Dependence of mass discrimination on collision-cell properties was studied in the mass range 10 u (boron) to 238 u (uranium). Isotopic analysis of the elements affected by mass-spectrometric interference, Ca, Fe, and Se, was performed using a Meinhard nebulizer and an ultrasonic nebulizer (USN). The measured isotope ratios were comparable with tabulated values from IUPAC. Precision of 0.26%, 0.19%, and 0.12%, respectively, and accuracy of 0.13% 0.25%, and 0.92%, respectively, was achieved for isotope ratios 44Ca/ 40Ca and 56Fe/57Fe in 10 microg L(-1) solution nebulized by means of a USN and for 78Se/80Se in 100 microg L(-1) solution nebulized by means of a Meinhard nebulizer.

Collision-spike sputtering of Au nanoparticles

DOE PAGES

Sandoval, Luis; Urbassek, Herbert M.

2015-08-06

Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; themore » remainder is transported away by the transmitted projectile and the ejecta. As a result, the sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.« less

Proceeding of the 18th Intl. Workshop on Inelastic Ion-Surface Collisions (IISC-18)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reinhold, Carlos O; Krstic, Predrag S; Meyer, Fred W

2011-01-01

The main topics of this proceedings were: (1) Energy loss of particles at surfaces; (2) Scattering of atoms, ions, molecules and clusters; (3) Charge exchange between particles and surfaces; (4) Ion induced desorption, electronic and kinetic sputtering; (5) Defect formation, surface modification and nanostructuring; (6) Electron, photon and secondary ion emission due to particle impact on surfaces; (7) Sputtering, fragmentation, cluster and ion formation in SIMS and SNMS; (8) Cluster/molecular and highly charged ion beams; and (9) Laser induced desorption.

Suboxide/subnitride formation on Ta masks during magnetic material etching by reactive plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hu; Muraki, Yu; Karahashi, Kazuhiro

2015-07-15

Etching characteristics of tantalum (Ta) masks used in magnetoresistive random-access memory etching processes by carbon monoxide and ammonium (CO/NH{sub 3}) or methanol (CH{sub 3}OH) plasmas have been examined by mass-selected ion beam experiments with in-situ surface analyses. It has been suggested in earlier studies that etching of magnetic materials, i.e., Fe, Ni, Co, and their alloys, by such plasmas is mostly due to physical sputtering and etch selectivity of the process arises from etch resistance (i.e., low-sputtering yield) of the hard mask materials such as Ta. In this study, it is shown that, during Ta etching by energetic CO{sup +}more » or N{sup +} ions, suboxides or subnitrides are formed on the Ta surface, which reduces the apparent sputtering yield of Ta. It is also shown that the sputtering yield of Ta by energetic CO{sup +} or N{sup +} ions has a strong dependence on the angle of ion incidence, which suggests a correlation between the sputtering yield and the oxidation states of Ta in the suboxide or subnitride; the higher the oxidation state of Ta, the lower is the sputtering yield. These data account for the observed etch selectivity by CO/NH{sub 3} and CH{sub 3}OH plasmas.« less

New Cs sputter ion source with polyatomic ion beams for secondary ion mass spectrometry applications

NASA Astrophysics Data System (ADS)

Belykh, S. F.; Palitsin, V. V.; Veryovkin, I. V.; Kovarsky, A. P.; Chang, R. J. H.; Adriaens, A.; Dowsett, M. G.; Adams, F.

2007-08-01

A simple design for a cesium sputter ion source compatible with vacuum and ion-optical systems as well as with electronics of the commercially available Cameca IMS-4f instrument is reported. This ion source has been tested with the cluster primary ions of Sin- and Cun-. Our experiments with surface characterization and depth profiling conducted to date demonstrate improvements of the analytical capabilities of the secondary ion mass spectrometry instrument due to the nonadditive enhancement of secondary ion emission and shorter ion ranges of polyatomic projectiles compared to atomic ones with the same impact energy.

Measured density of copper atoms in the ground and metastable states in argon magnetron discharge correlated with the deposition rate

NASA Astrophysics Data System (ADS)

Naghshara, H.; Sobhanian, S.; Khorram, S.; Sadeghi, N.

2011-01-01

In a dc-magnetron discharge with argon feed gas, densities of copper atoms in the ground state Cu(2S1/2) and metastable state Cu*(2D5/2) were measured by the resonance absorption technique, using a commercial hollow cathode lamp as light source. The operating conditions were 0.3-14 µbar argon pressure and 10-200 W magnetron discharge power. The deposition rate of copper in a substrate positioned at 18 cm from the target was also measured with a quartz microbalance. The gas temperature, in the range 300-380 K, was deduced from the emission spectral profile of N2(C 3Πu - B 3Πg) 0-0 band at 337 nm when trace of nitrogen was added to the argon feed gas. The isotope-shifts and hyperfine structures of electronic states of Cu have been taken into account to deduce the emission and absorption line profiles, and hence for the determination of atoms' densities from the measured absorption rates. To prevent error in the evaluation of Cu density, attributed to the line profile distortion by auto-absorption inside the lamp, the lamp current was limited to 5 mA. Density of Cu(2S1/2) atoms and deposition rate both increased with the enhanced magnetron discharge power. But at fixed power, the copper density augmented with argon pressure whereas the deposition rate followed the opposite trend. Whatever the gas pressure, the density of Cu*(2D5/2) metastable atoms remained below the detection limit of 1 × 1010 cm-3 for magnetron discharge powers below 50 W and hence increased much more rapidly than the density of Cu(2S1/2) atoms, over passing this later at some discharge power, whose value decreases with increasing argon pressure. This behaviour is believed to result from the enhancement of plasma density with increasing discharge power and argon pressure, which would increase the excitation rate of copper into metastable states. At fixed pressure, the deposition rate followed the same trend as the total density of copper atoms in the ground and metastable states. Two important conclusions of this work are (i) copper atoms sputtered from the target under ion bombardment are almost all in the ground state Cu(2S1/2) and hence in the plasma volume they can be excited into the metastable states; (ii) all atoms in the long-lived ground and metastable states contribute to the deposition of copper layer on the substrate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yun, Dong-Jin; Chung, JaeGwan; Jung, Changhoon

The material arrangement and energy level alignment of an organic bilayer comprising of phenyl-c71-butyric-acid-methyl ester (PCBM-71) and pentacene were studied using ultraviolet photoelectron spectroscopy (UPS) and the argon gas cluster ion beam (GCIB) sputtering process. Although there is a small difference in the full width at half maximum of the carbon C 1s core level peaks and differences in the oxygen O 1s core levels of an X-ray photoemission spectroscopy spectra, these differences are insufficient to clearly distinguish between PCBM-71 and pentacene layers and to classify the interface and bulk regions. On the other hand, the valence band structures inmore » the UPS spectra contain completely distinct configurations for the PCBM-71 and pentacene layers, even when they have similar atomic compositions. According to the valence band structures of the PCBM-71/pentacene/electrodes, the highest unoccupied molecular orbital (HOMO) region of pentacene is at least 0.8 eV closer to the Fermi level than that of PCBM-71 and it does not overlap with any of the chemical states in the valence band structure of PCBM-71. Therefore, by just following the variations in the area of the HOMO region of pentacene, the interface/bulk regions of the PCBM/pentacene layers were distinctly categorized. Besides, the variation of valence band structures as a function of the Ar GCIB sputtering time fully corroborated with the surface morphologies observed in the atomic force microscope images. In summary, we believe that the novel approach, which involves UPS analysis in conjunction with Ar GCIB sputtering, can be one of the best methods to characterize the material distribution and energy level alignments of stacks of organic layers.« less

Modeling of beryllium sputtering and re-deposition in fusion reactor plasma facing components

NASA Astrophysics Data System (ADS)

Zimin, A. M.; Danelyan, L. S.; Elistratov, N. G.; Gureev, V. M.; Guseva, M. I.; Kolbasov, B. N.; Kulikauskas, V. S.; Stolyarova, V. G.; Vasiliev, N. N.; Zatekin, V. V.

2004-08-01

Quantitative characteristics of Be-sputtering by hydrogen isotope ions in a magnetron sputtering system, the microstructure and composition of the sputtered and re-deposited layers were studied. The energies of H + and D + ions varied from 200 to 300 eV. The ion flux density was ˜3 × 10 21 m -2 s -1. The irradiation doses were up to 4 × 10 25 m -2. For modeling of the sputtered Be-atom re-deposition at increased deuterium pressures (up to 0.07 torr), a mode of operation with their effective return to the Be-target surface was implemented. An atomic ratio O/Be ≅ 0.8 was measured in the re-deposited layers. A ratio D/Be decreases from 0.15 at 375 K to 0.05 at 575 K and slightly grows in the presence of carbon and tungsten. The oxygen concentration in the sputtered layers does not exceed 3 at.%. The atomic ratio D/Be decreases there from 0.07 to 0.03 at target temperatures increase from 350 to 420 K.

Anorthite sputtering by H + and Ar q+ (q = 1-9) at solar wind velocities

DOE PAGES

Hijazi, Hussein Dib; Bannister, Mark E.; Meyer, III, Harry M.; ...

2014-10-16

Here, we report sputtering measurements of anorthite-like material, taken to be representative of soils found in the lunar highlands, impacted by singly and multicharged ions representative of the solar wind. The ions investigated include protons, as well as singly and multicharged Ar ions (as proxies for the nonreactive heavy solar wind constituents), in the charge state range +1 to +9, at fixed solar wind-relevant impact velocities of 165 and 310 km/s (0.25 keV/amu and 0.5 keV/amu). A quartz microbalance approach (QCM) for determination of total sputtering yields was used. The goal of the measurements was to determine the sputtering contributionmore » of the heavy, multicharged minority solar wind constituents in comparison to that due to the dominant H + fraction. The QCM results show a yield increase of a factor of about 80 for Ar + versus H + sputtering and an enhancement by a factor of 1.67 between Ar 9+ and Ar +, which is a clear indication of a potential sputtering effect.« less

Influence of argon and oxygen pressure ratio on bipolar-resistive switching characteristics of CeO2- x thin films deposited at room temperature

NASA Astrophysics Data System (ADS)

Ismail, Muhammad; Ullah, Rehmat; Hussain, Riaz; Talib, Ijaz; Rana, Anwar Manzoor; Hussain, Muhammad; Mahmood, Khalid; Hussain, Fayyaz; Ahmed, Ejaz; Bao, Dinghua

2018-02-01

Cerium oxide (CeO2-x) film was deposited on Pt/Ti/SiO2/Si substrate by rf magnetron sputtering at room temperature. Resistive switching characteristics of these ceria films have been improved by increasing oxygen content during deposition process. Endurance and statistical analyses indicate that the operating stability of CeO2-x-based memory is highly dependent on the oxygen content. Results indicate that CeO2-x film-based RRAM devices exhibit optimum performance when fabricated at an argon/oxygen ratio of 6:24. An increase in the oxygen content introduced during CeO2-x film deposition not only stabilizes the conventional bipolar RS but also improves excellent switching uniformity such as large ON/OFF ratio (102), excellent switching device-to-device uniformity and good sweep endurance over 500 repeated RS cycles. Conduction in the low-resistance state (LRS) as well as in the low bias field region in the high-resistance state (HRS) is found to be Ohmic and thus supports the conductive filament (CF) theory. In the high voltage region of HRS, space charge limited conduction (SCLC) and Schottky emission are found to be the dominant conduction mechanisms. A feasible filamentary RS mechanism based on the movement of oxygen ions/vacancies under the bias voltage has been discussed.

Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Kunj, Saurabh; Sreenivas, K.

2016-05-01

Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunj, Saurabh, E-mail: saurabhkunj22@gmail.com; Sreenivas, K.

2016-05-23

Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O{sub 2}/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

Ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline yttria-stabilized zirconia

NASA Astrophysics Data System (ADS)

Sillassen, M.; Eklund, P.; Sridharan, M.; Pryds, N.; Bonanos, N.; Bøttiger, J.

2009-05-01

Thermally stable, stoichiometric, cubic yttria-stabilized zirconia (YSZ) thin-film electrolytes have been synthesized by reactive pulsed dc magnetron sputtering from a Zr-Y (80/20 at. %) alloy target. Films deposited at floating potential had a ⟨111⟩ texture. Single-line profile analysis of the 111 x-ray diffraction peak yielded a grain size of ˜20 nm and a microstrain of ˜2% regardless of deposition temperature. Films deposited at 400 °C and selected bias voltages in the range from -70 to -200 V showed a reduced grain size for higher bias voltages, yielding a grain size of ˜6 nm and a microstrain of ˜2.5% at bias voltages of -175 and -200 V with additional incorporation of argon. The films were thermally stable; very limited grain coarsening was observed up to an annealing temperature of 800 °C. Temperature-dependent impedance spectroscopy analysis of the YSZ films with Ag electrodes showed that the in-plane ionic conductivity was within one order of magnitude higher in films deposited with substrate bias corresponding to a decrease in grain size compared to films deposited at floating potential. This suggests that there is a significant contribution to the ionic conductivity from grain boundaries. The activation energy for oxygen ion migration was determined to be between 1.14 and 1.30 eV.

Ion beam sputtering of in situ superconducting Y-Ba-Cu-O films

NASA Astrophysics Data System (ADS)

Klein, J. D.; Yen, A.; Clauson, S. L.

1990-05-01

Oriented superconducting YBa2Cu3O7 thin films were deposited on yttria stabilized zirconia and SrTiO3 substrates by ion-beam sputtering of a nonstoichiometric oxide target. The films exhibited zero-resistance critical temperatures as high as 83.5 K without post-deposition anneals. Both the deposition rate and the c-lattice parameter data displayed two distinct regimes of dependence on the beam power of the ion source. Low-power sputtering yielded films with large c-dimensions and low Tc. Higher-power sputtering produced a continuous decrease in the c-lattice parameter and increase in critical temperature. Films having the smaller c-lattice parameters were Cu rich. The Cu content of films deposited at beam voltages of 800 V and above increased with increasing beam power.

Sputtering Erosion Measurement on Boron Nitride as a Hall Thruster Material

NASA Technical Reports Server (NTRS)

Britton, Melissa; Waters, Deborah; Messer, Russell; Sechkar, Edward; Banks, Bruce

2002-01-01

The durability of a high-powered Hall thruster may be limited by the sputter erosion resistance of its components. During normal operation, a small fraction of the accelerated ions will impact the interior of the main discharge channel, causing its gradual erosion. A laboratory experiment was conducted to simulate the sputter erosion of a Hall thruster. Tests of sputter etch rate were carried out using 300 to 1000 eV Xenon ions impinging on boron nitride substrates with angles of attack ranging from 30 to 75 degrees from horizontal. The erosion rates varied from 3.41 to 14.37 Angstroms/[sec(mA/sq cm)] and were found to depend on the ion energy and angle of attack, which is consistent with the behavior of other materials.

Ion beam deposition of in situ superconducting Y-Ba-Cu-O films

NASA Astrophysics Data System (ADS)

Klein, J. D.; Yen, A.; Clauson, S. L.

1990-01-01

Oriented superconducting YBa2Cu3O7 thin films were deposited on yttria-stabilized zirconia substrates by ion beam sputtering of a nonstoichiometric oxide target. The films exhibited zero-resistance critical temperatures as high as 80.5 K without post-deposition anneals. Both the deposition rate and the c lattice parameter data displayed two distinct regimes of dependence on the beam power of the ion source. Low-power sputtering yielded films with large c dimensions and low Tc's. Higher power sputtering produced a continuous decrease in the c lattice parameter and an increase in critical temperatures.

Spectral artefacts post sputter-etching and how to cope with them - A case study of XPS on nitride-based coatings using monoatomic and cluster ion beams

NASA Astrophysics Data System (ADS)

Lewin, Erik; Counsell, Jonathan; Patscheider, Jörg

2018-06-01

The issue of artefacts due to sputter-etching has been investigated for a group of AlN-based thin film materials with varying thermodynamical stability. Stability of the materials was controlled by alloying AlN with the group 14 elements Si, Ge or Sn in two different concentrations. The coatings were sputter-etched with monoatomic Ar+ with energies between 0.2 and 4.0 keV to study the sensitivity of the materials for sputter damage. The use of Arn+ clusters to remove an oxidised surface layer was also evaluated for a selected sample. The spectra were compared to pristine spectra obtained after in-vacuo sample transfer from the synthesis chamber to the analysis instrument. It was found that the all samples were affected by high energy (4 keV) Ar+ ions to varying degrees. The determining factors for the amount of observed damage were found to be the materials' enthalpy of formation, where a threshold value seems to exist at approximately -1.25 eV/atom (∼-120 kJ/mol atoms). For each sample, the observed amount of damage was found to have a linear dependence to the energy deposited by the ion beam per volume removed material. Despite the occurrence of sputter-damage in all samples, etching settings that result in almost artefact-free spectral data were found; using either very low energy (i.e. 200 eV) monoatomic ions, or an appropriate combination of ion cluster size and energy. The present study underlines that analysis post sputter-etching must be carried out with an awareness of possible sputter-induced artefacts.

Nanofabrication Technology for Production of Quantum Nano-Electronic Devices Integrating Niobium Electrodes and Optically Transparent Gates

DTIC Science & Technology

2018-01-01

conditions (pending input from University of California San Diego (UCSD)/Nano3). After dose testing, resist development and bake SF6 etching is done...conditions. After the resist development and bake , a 2-second descum oxygen-plasma exposure is performed followed by RF sputtering at 100 watts in argon of

Variable range hopping in ZnO films

NASA Astrophysics Data System (ADS)

Ali, Nasir; Ghosh, Subhasis

2018-04-01

We report the variable range hopping in ZnO films grown by RF magnetron sputtering in different argon and oxygen partial pressure. It has been found that Mott variable range hopping dominant over Efros variable range hopping in all ZnO films. It also has been found that hopping distance and energy increases with increasing oxygen partial pressure.

Mixed composition materials suitable for vacuum web sputter coating

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Rutledge, Sharon K.; Dever, Joyce A.; Bruckner, Eric J.; Walters, Patricia; Hambourger, Paul D.

1996-01-01

Ion beam sputter deposition techniques were used to investigate simultaneous sputter etching of two component targets so as to produce mixed composition films. Although sputter deposition has been largely confined to metals and metal oxides, at least one polymeric material, poly-tetra-fluorethylene, has been demonstrated to produce sputtered fragments which repolymerize upon deposition to produce a highly cross-linked fluoropolymer resembling that of the parent target Fluoropolymer-filled silicon dioxide and fluoropolymer-filled aluminum oxide coatings have been deposited by means of ion beam sputter coat deposition resulting in films having material properties suitable for aerospace and commercial applications. The addition of fluoropolymer to silicon dioxide films was found to increase the hydrophobicity of the resulting mixed films; however, adding fluoropolymer to aluminum oxide films resulted in a reduction in hydrophobicity, thought to be caused by aluminum fluoride formation.

Solar Wind Sputtering of Lunar Surface Materials: Role and Some Possible Implications of Potential Sputtering

NASA Technical Reports Server (NTRS)

Barghouty, A. F.; Adams, J. H., Jr.; Meyer, F.; Reinhold, c.

2010-01-01

Solar-wind induced sputtering of the lunar surface includes, in principle, both kinetic and potential sputtering. The role of the latter mechanism, however, in many focused studies has not been properly ascertained due partly to lack of data but can also be attributed to the assertion that the contribution of solar-wind heavy ions to the total sputtering is quite low due to their low number density compared to solar-wind protons. Limited laboratory measurements show marked enhancements in the sputter yields of slow-moving, highly-charged ions impacting oxides. Lunar surface sputtering yields are important as they affect, e.g., estimates of the compositional changes in the lunar surface, its erosion rate, as well as its contribution to the exosphere as well as estimates of hydrogen and water contents. Since the typical range of solar-wind ions at 1 keV/amu is comparable to the thickness of the amorphous rim found on lunar soil grains, i.e. few 10s nm, lunar simulant samples JSC-1A AGGL are specifically enhanced to have such rims in addition to the other known characteristics of the actual lunar soil particles. However, most, if not all laboratory studies of potential sputtering were carried out in single crystal targets, quite different from the rim s amorphous structure. The effect of this structural difference on the extent of potential sputtering has not, to our knowledge, been investigated to date.

High-temperature, low-cycle fatigue of advanced copper-base alloys for rocket nozzles. Part 2: NASA 1.1, Glidcop, and sputtered copper alloys

NASA Technical Reports Server (NTRS)

Conway, J. B.; Stentz, R. H.; Berling, J. T.

1974-01-01

Short-term tensile and low-cycle fatigue data are reported for five advance copper-base alloys: Sputtered Zr-Cu as received, sputtered Zr-Cu heat-treated, Glidcop AL-10, and NASA alloys 1-1A and 1-1B. Tensile tests were performed in argon at 538 C using an axial strain rate of 0.002/sec. Yield strength and ultimate tensile strength data are reported along with reduction in area values. Axial strain controlled low-cycle fatigue tests were performed in argon at 538C using an axial strain rate of 0.002/sec to define the fatigue life over the range from 100 to 3000 cycles for the five materials studied. It was found that the fatigue characteristics of the NASA 1-1A and NASA 1-1B compositions are identical and represent fatique life values which are much greater than those for the other materials tested. The effect of temperature on NASA 1-1B alloy at a strain rate of 0.002/sec was evaluated along with the effect of strain rates of 0.0004 and 0.01/sec at 538 C. Hold-time data are reported for the NASA 1-1B alloy at 538 C using 5 minute hold periods in tension only and compression only at two different strain range values. Hold periods in tension were much more detrimental than hold periods in compression.

Lead Pipe Scale Analysis Using Broad-Beam Argon Ion Milling to Elucidate Drinking Water Corrosion

EPA Science Inventory

Herein, we compared the characterization of lead pipe scale removed from a drinking water distribution system using two different cross section methods (conventional polishing and argon ion beam etching). The pipe scale solids were analyzed using scanning electron microscopy (SEM...

Development of ion beam sputtering techniques for actinide target preparation

NASA Astrophysics Data System (ADS)

Aaron, W. S.; Zevenbergen, L. A.; Adair, H. L.

1985-06-01

Ion beam sputtering is a routine method for the preparation of thin films used as targets because it allows the use of a minimum quantity of starting material, and losses are much lower than most other vacuum deposition techniques. Work is underway in the Isotope Research Materials Laboratory (IRML) at ORNL to develop the techniques that will make the preparation of actinide targets up to 100 μg/cm 2 by ion beam sputtering a routinely available service from IRML. The preparation of the actinide material in a form suitable for sputtering is a key to this technique, as is designing a sputtering system that allows the flexibility required for custom-ordered target production. At present, development work is being conducted on low-activity actinides in a bench-top system. The system will then be installed in a hood or glove box approved for radioactive materials handling where processing of radium, actinium, and plutonium isotopes among others will be performed.

Inert gas ion source program

NASA Technical Reports Server (NTRS)

Ramsey, W. D.

1978-01-01

THe original 12 cm hexagonal magneto-electrostatic containment discharge chamber has been optimized for argon and xenon operation. Argon mass utilization efficiencies of 65 to 77 percent were achieved at keeper-plus-main discharge energy consumptions of 200 to 458 eV/ion, respectively. Xenon performance of 84 to 96 percent mass utilization was realized at 203 to 350 eV/ion. The optimization process and test results are discussed.

Large area ion beam sputtered YBa2Cu3O(7-delta) films for novel device structures

NASA Astrophysics Data System (ADS)

Gauzzi, A.; Lucia, M. L.; Kellett, B. J.; James, J. H.; Pavuna, D.

1992-03-01

A simple single-target ion-beam system is employed to manufacture large areas of uniformly superconducting YBa2Cu3O(7-delta) films which can be reproduced. The required '123' stoichiometry is transferred from the target to the substrate when ion-beam power, target/ion-beam angle, and target temperature are adequately controlled. Ion-beam sputtering is experimentally demonstrated to be an effective technique for producing homogeneous YBa2Cu3O(7-delta) films.

Enhanced etching of tin-doped indium oxide due to surface modification by hydrogen ion injection

NASA Astrophysics Data System (ADS)

Li, Hu; Karahashi, Kazuhiro; Friederich, Pascal; Fink, Karin; Fukasawa, Masanaga; Hirata, Akiko; Nagahata, Kazunori; Tatsumi, Tetsuya; Wenzel, Wolfgang; Hamaguchi, Satoshi

2018-06-01

It is known that the etching yield (i.e., sputtering yield) of tin-doped indium oxide (ITO) by hydrocarbon ions (CH x +) is higher than its corresponding physical sputtering yield [H. Li et al., J. Vac. Sci. Technol. A 33, 060606 (2015)]. In this study, the effects of hydrogen in the incident hydrocarbon ion beam on the etching yield of ITO have been examined experimentally and theoretically with the use of a mass-selected ion beam system and by first-principles quantum mechanical (QM) simulation. As in the case of ZnO [H. Li et al., J. Vac. Sci. Technol. A 35, 05C303 (2017)], mass-selected ion beam experiments have shown that the physical sputtering yield of ITO by chemically inert Ne ions increases after a pretreatment of the ITO film by energetic hydrogen ion injection. First-principles QM simulation of the interaction of In2O3 with hydrogen atoms shows that hydrogen atoms embedded in In2O3 readily form hydroxyl (OH) groups and weaken or break In–O bonds around the hydrogen atoms, making the In2O3 film less resistant to physical sputtering. This is consistent with experimental observation of the enhanced etching yields of ITO by CH x + ions, considering the fact that hydrogen atoms of the incident CH x + ions are embedded into ITO during the etching process.

Nitrogen incorporation in carbon nitride films produced by direct and dual ion-beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abrasonis, G.; Gago, R.; Jimenez, I.

2005-10-01

Carbon (C) and carbon nitride (CN{sub x}) films were grown on Si(100) substrates by direct ion-beam sputtering (IBS) of a carbon target at different substrate temperatures (room temperature-450 deg. C) and Ar/N{sub 2} sputtering gas mixtures. Additionally, the effect of concurrent nitrogen-ion assistance during the growth of CN{sub x} films by IBS was also investigated. The samples were analyzed by elastic recoil detection analysis (ERDA) and x-ray absorption near-edge spectroscopy (XANES). The ERDA results showed that significant nitrogen amount (up to 20 at. %) was incorporated in the films, without any other nitrogen source but the N{sub 2}-containing sputtering gas.more » The nitrogen concentration is proportional to the N{sub 2} content in the sputtering beam and no saturation limit is reached under the present working conditions. The film areal density derived from ERDA revealed a decrease in the amount of deposited material at increasing growth temperature, with a correlation between the C and N losses. The XANES results indicate that N atoms are efficiently incorporated into the carbon network and can be found in different bonding environments, such as pyridinelike, nitrilelike, graphitelike, and embedded N{sub 2} molecules. The contribution of molecular and pyridinelike nitrogen decreases when the temperature increases while the contribution of the nitrilelike nitrogen increases. The concurrent nitrogen ion assistance resulted in the significant increase of the nitrogen content in the film but it induced a further reduction of the deposited material. Additionally, the assisting ions inhibited the formation of the nitrilelike configurations while promoting nitrogen environments in graphitelike positions. The nitrogen incorporation and release mechanisms are discussed in terms of film growth precursors, ion bombardment effects, and chemical sputtering.« less

Pulsed-DC selfsputtering of copper

NASA Astrophysics Data System (ADS)

Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

2008-03-01

At standard magnetron sputtering conditions (argon pressure ~0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (~550W/cm2). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%.

Laser-Induced Fluorescence Helps Diagnose Plasma Processes

NASA Technical Reports Server (NTRS)

Beattie, J. R.; Mattosian, J. N.; Gaeta, C. J.; Turley, R. S.; Williams, J. D.; Williamson, W. S.

1994-01-01

Technique developed to provide in situ monitoring of rates of ion sputter erosion of accelerator electrodes in ion thrusters also used for ground-based applications to monitor, calibrate, and otherwise diagnose plasma processes in fabrication of electronic and optical devices. Involves use of laser-induced-fluorescence measurements, which provide information on rates of ion etching, inferred rates of sputter deposition, and concentrations of contaminants.

Electronic sputtering of vitreous SiO2: Experimental and modeling results

NASA Astrophysics Data System (ADS)

Toulemonde, M.; Assmann, W.; Trautmann, C.

2016-07-01

The irradiation of solids with swift heavy ions leads to pronounced surface and bulk effects controlled by the electronic energy loss of the projectiles. In contrast to the formation of ion tracks in bulk materials, the concomitant emission of atoms from the surface is much less investigated. Sputtering experiments with different ions (58Ni, 127I and 197Au) at energies around 1.2 MeV/u were performed on vitreous SiO2 (a-SiO2) in order to quantify the emission rates and compare them with data for crystalline SiO2 quartz. Stoichiometry of the sputtering process was verified by monitoring the thickness decreases of a thin SiO2 film deposited on a Si substrate. Angular distributions of the emitted atoms were measured by collecting sputtered atoms on arc-shaped Cu catcher foils. Subsequent analysis of the number of Si atoms deposited on the catcher foils was quantified by elastic recoil detection analysis providing differential as well as total sputtering yields. Compared to existing data for crystalline SiO2, the total sputtering yields for vitreous SiO2 are by a factor of about five larger. Differences in the sputtering rate and track formation characteristics between amorphous and crystalline SiO2 are discussed within the frame of the inelastic thermal spike model.

Transport of Sputtered Carbon During Ground-Based Life Testing of Ion Thrusters

NASA Technical Reports Server (NTRS)

Marker, Colin L.; Clemons, Lucas A.; Banks, Bruce A.; Miller, Sharon; Snyder, Aaron; Hung, Ching-Cheh; Karniotis, Christina A.; Waters, Deborah L.

2005-01-01

High voltage, high power electron bombardment ion thrusters needed for deep space missions will be required to be operated for long durations in space as well as during ground laboratory life testing. Carbon based ion optics are being considered for such thrusters. The sputter deposition of carbon and arc vaporized carbon flakes from long duration operation of ion thrusters can result in deposition on insulating surfaces, causing them to become conducting. Because the sticking coefficient is less than one, secondary deposition needs to be considered to assure that shorting of critical components does not occur. The sticking coefficient for sputtered carbon and arc vaporized carbon is measured as well as directional ejection distribution data for carbon that does not stick upon first impact.

Surface normal velocity distribution of sputtered Zr-atoms for light-ion irradiation

NASA Astrophysics Data System (ADS)

Bay, H. L.; Berres, W.; Hintz, E.

1982-03-01

The velocity distribution of sputtered Zr-atoms has been measured for 8 keV Ar + and He + ions and 2.5 keV D + ion irradiation at normal incidence. The measurements were performed with the aid of laser induced fluorescence spectroscopy (LIFS) using a CW-laser pumped dye-laser. The influence of the measuring geometry was investigated and found to be in good agreement with calculation. For light-ion sputtering the collision-cascade theory is no longer applicable. Here a distinct shift in the velocity distributions towards lower velocities compared with the Ar results was found. The shift can be correlated to anisotropic effects in connection with the change in the maximum recoil energy Tm in the cascade.

Step edge sputtering yield at grazing incidence ion bombardment.

PubMed

Hansen, Henri; Polop, Celia; Michely, Thomas; Friedrich, Andreas; Urbassek, Herbert M

2004-06-18

The surface morphology of Pt(111) was investigated by scanning tunneling microscopy after 5 keV Ar+ ion bombardment at grazing incidence in dependence of the ion fluence and in the temperature range between 625 and 720 K. The average erosion rate was found to be strongly dependent on the ion fluence and the substrate temperature during bombardment. This dependence is traced back to the variation of step concentration with temperature and fluence. We develop a simple model allowing us to determine separately the constant sputtering yields for terraces and for impact area stripes in front of ascending steps. The experimentally determined yield of these stripes--the step-edge sputtering yield--is in excellent agreement with our molecular dynamics simulations performed for the experimental situation.

Synthesis and annealing study of RF sputtered ZnO thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Shushant Kumar, E-mail: singhshushant86@gmail.com; Sharma, Himanshu; Singhal, R.

2016-05-23

In this paper, we have investigated the annealing effect on optical and structural properties of ZnO thin films, synthesized by RF magnetron sputtering. ZnO thin films were deposited on glass and silicon substrates simultaneously at a substrate temperature of 300 °C using Argon gas in sputtering chamber. Thickness of as deposited ZnO thin film was found to be ~155 nm, calculated by Rutherford backscattering spectroscopy (RBS). These films were annealed at 400 °C and 500 °C temperature in the continuous flow of oxygen gas for 1 hour in tube furnace. X-ray diffraction analysis confirmed the formation of hexagonal wurtzite structuremore » of ZnO thin film along the c-axis (002) orientation. Transmittance of thin films was increased with increasing the annealing temperature estimated by UV-visible transmission spectroscopy. Quality and texture of the thin films were improved with annealing temperature, estimated by Raman spectroscopy.« less

Characterization of polycrystalline nickel cobaltite nanostructures prepared by DC plasma magnetron co-sputtering for gas sensing applications

NASA Astrophysics Data System (ADS)

Hammadi, Oday A.; Naji, Noor E.

2018-03-01

In this work, a gas sensor is fabricated from polycrystalline nickel cobaltite nano films deposited on transparent substrates by closed-field unbalanced dual-magnetrons (CFUBDM) co-sputtering technique. Two targets of nickel and cobalt are mounted on the cathode of discharge system and co-sputtered by direct current (DC) argon discharge plasma in presence of oxygen as a reactive gas. The total gas pressure is 0.5 mbar and the mixing ratio of Ar:O2 gases is 5:1. The characterization measurements performed on the prepared films show that their transmittance increases with the incident wavelength, the polycrystalline structure includes 5 crystallographic planes, the average particle size is about 35 nm, the electrical conductivity is linearly increasing with increasing temperature, and the activation energy is about 0.41 eV. These films show high sensitivity to ethanol vapor.

Total and Differential Sputter Yields of Boron Nitride Measured by Quartz Crystal Microbalance (Preprint)

DTIC Science & Technology

2009-08-20

Nomenclature As = QCM sensor area E = ion energy E* = characteristic energy describing the differential sputter yield profile shape Eth...We report differential and total sputter yields for several grades of BN at ion energies down to 60 eV, obtained with a QCM deposition sensor 3-7,9...personal computer with LabView is used for data logging. Detailed discussion of the QCM sensor is provided in subsection IIF. B. Definition of Angles

Sputtering of sodium on the planet Mercury

NASA Technical Reports Server (NTRS)

Mcgrath, M. A.; Johnson, R. E.; Lanzerotti, L. J.

1986-01-01

It is shown here that ion sputtering cannot account for the observed neutral sodium vapor column density on Mercury, but that it is an important loss mechanism for Na. Photons are likely to be the dominant stimulus, both directly through photodesorption and indirectly through thermal desorption of absorbed Na. It is concluded that the atmosphere produced is characterized by the planet's surface temperature, with the ion-sputtered Na contributing to a lesser, but more extended, component of the atmosphere.

Magnetic Phase Transition in Ion-Irradiated Ultrathin CoN Films via Magneto-Optic Faraday Effect.

PubMed

Su, Chiung-Wu; Chang, Yen-Chu; Chang, Sheng-Chi

2013-11-15

The magnetic properties of 1 nm thick in-plane anisotropic Co ultrathin film on ZnO(0001) were investigated through successive 500 eV nitrogen-ion sputtering. Magneto-optical Faraday effects were used to observe the evolution of the ion-irradiated sample in longitudinal and perpendicular magnetic fields. The ferromagnetic phase of the initial in-plane anisotropic fcc β-Co phase transformation to β-Co(N) phase was terminated at paramagnetic CoN x phase. In-plane anisotropy with weak out-of-plane anisotropy of the Co/ZnO sample was initially observed in the as-grown condition. In the sputtering process, the N⁺ ions induced simultaneous sputtering and doping. An abrupt spin reorientation behavior from in-plane to out-of-plane was found under prolonged sputtering condition. The existence of perpendicular anisotropy measured from the out-of-plane Faraday effect may be attributed to the co-existence of residual β-Co and Co₄N exchange bonding force by the gradual depletion of Co-N thickness.

Magnetron with flux switching cathode and method of operation

DOEpatents

Aaron, D.B.; Wiley, J.D.

1989-09-12

A magnetron sputtering apparatus is formed with a plurality of cells each for generating an independent magnetic field within a different region in the chamber of the apparatus. Each magnetic field aids in maintaining an ion plasma in the respective region of the chamber. One of a plurality of sputtering material targets is positioned on an electrode adjacent to each region so that said ions strike the target ejecting some of the target material. By selectively generating each magnetic field, the ion plasma may be moved from region to region to sputter material from different targets. The sputtered material becomes deposited on a substrate mounted on another electrode within the chamber. The duty cycle of each cell can be dynamically varied during the deposition to produce a layer having a graded composition throughout its thickness. 5 figs.

Magnetron with flux switching cathode and method of operation

DOEpatents

Aaron, David B.; Wiley, John D.

1989-01-01

A magnetron sputtering apparatus is formed with a plurality of cells each for generating an independent magnetic field within a different region in the chamber of the apparatus. Each magnetic field aids in maintaining an ion plasma in the respective region of the chamber. One of a plurality of sputtering material targets is positioned on an electrode adjacent to each region so that said ions strike the target ejecting some of the target material. By selectively generating each magnetic field, the ion plasma may be moved from region to region to sputter material from different targets. The sputtered material becomes deposited on a substrate mounted on another electrode within the chamber. The duty cycle of each cell can be dynamically varied during the deposition to produce a layer having a graded composition throughout its thickness.

The Use of OXYGEN-18 in the Development of Methods for Controlled Sputter Deposition of High Critical Transition Temperature Material Thin Films of Predicted Composition and Good Uniformity

NASA Astrophysics Data System (ADS)

Tidrow, Steven Clay

Two primary concerns, in the sputter deposition of high T_{c} material films, are the prevention of oxygen deficiency in the films and the elimination of the negative ion effect. "Oxygen deficiency" occurs when the amount of oxygen incorporated into the film is less than the amount of oxygen required to form the superconducting material lattice. Oxygen deficiency is due to the volatile nature of oxygen. The negative ion effect occurs when an atom or molecule (typically oxygen) gains an extra electron, is accelerated away from the target and impinges upon a film being grown directly in front of the sputtering target. The impinging particle has enough energy to cause resputtering of the deposited film. The presence of Sr and to a greater extent Ba, may enhance the negative ion effect in these materials. However, it is oxygen which readily forms negative ions that is primarily responsible for the negative ion effect. Thus, oxygen must be given special attention in the sputter deposition of high T_{c} material films. A specially designed sputtering system is used to demonstrate that the negative ion effect can be reduced such that large uniform high T_{c} material films possessing predicted and repeated composition can be grown in an on-axis arrangement. Utilizing this same sputtering system and the volatile nature of oxygen, it is demonstrated that oxygen processes occurring in the chamber during growth of high T_ {c} material films can be investigated using the tracer ^{18}O. In particular, it is shown that ^{18}O can be utilized as a tool for (1) investigating the negative ion effect, (2) investigating oxygen incorporation into high T_{c} material films, (3) investigating oxygen incorporation into the target, (4) tailoring films for oxygen migration and interface investigations and (5) tailoring films for the other specific oxygen investigations. Such sputtering systems that utilize the tracer ^{18}O are necessary for systematic growth of high T_ {c} material films for systematic investigations into the nature of these materials.

Sputtering yields of carbon based materials under high particle flux with low energy

NASA Astrophysics Data System (ADS)

Nakamura, K.; Nagase, A.; Dairaku, M.; Akiba, M.; Araki, M.; Okumura, Y.

1995-04-01

A new ion source which can produce high particle flux beams at low energies has been developed. This paper presents preliminary results on the sputtering yield of the carbon fiber reinforced composites (CFCs) measured with the new ion source. The sputtering yields of 1D and 2D CFCs, which are candidate materials for the divertor armour tiles, have been measured by the weight loss method under the hydrogen and deuterium particle fluxes of 2 ˜ 7 × 10 20/m 2 s at 50 ˜ 150 eV. Preferential sputtering of the matrix was observed on CFCs which included the matrix of 40 ˜ 60 w%. The energy dependence of the sputtering yields was weak. The sputtering yields of CFCs normally irradiated with deuterium beam were from 0.073 to 0.095, and were around three times larger than those with hydrogen beam.

Transmission sputtering under diatomic molecule bombardment. Model calculations

NASA Astrophysics Data System (ADS)

Bitensky, I. S.

1996-04-01

Transmission sputtering means that emission of secondary particles is studied from the downstream side of a bombarded foil. Nonlinear effects in sputtering manifest themselves as a deviation of sputtering yield under molecular ion bombardment from the sum of the yields induced by the constituents at the same velocity. In the reflection geometry the overlap of the spike regions reaches maximum, while in transmission the degree of overlap depends on the projectile and on the foil thickness. It has been shown that the transmission sputtering yield can be described by a function of a scaling parameter determined by beam-foil characteristics and a mechanism of nonlinear sputtering. Calculations of the transmission yield have been made in the thermal spike and shock wave models. The results of calculations are compared with experimental data on phenylalanine molecular ion desorption from organic targets induced by Au + and Au 2+ impact. Suggestions for further experimental study are made.

Solutions for discharge chamber sputtering and anode deposit spalling in small mercury ion thrusters

NASA Technical Reports Server (NTRS)

Power, J. L.; Hiznay, D. J.

1975-01-01

Proposed solutions to the problems of sputter erosion and sputtered material spalling in the discharge chamber of small mercury ion thrusters are presented. The accelerated life test evaluated three such proposed solutions: (1) the use of tantalum as a single low sputter yield material for the exposed surfaces of the discharge chamber components subject to sputtering, (2) the use of a severely roughened anode surface to improve the adhesion of the sputter-deposited coating, and (3) the use of a wire cloth anode surface in order to limit the size of any coating flakes which might spall from it. Because of the promising results obtained in the accelerated life test with anode surfaces roughened by grit-blasting, experiments were carried out to optimize the grit-blasting procedure. The experimental results and an optimal grit-blasting procedure are presented.

Mechanical properties of carbon steel depending on the rate of the dose build-up of nitrogen and argon ions

NASA Astrophysics Data System (ADS)

Vorob'ev, V. L.; Bykov, P. V.; Bayankin, V. Ya.; Shushkov, A. A.; Vakhrushev, A. V.

2014-08-01

The effect of pulsed irradiation with argons and nitrogen ions on the mechanical properties, morphology, and structure of the surface layers of carbon steel St3 (0.2% C, 0.4% Mn, 0.15% Si, and Fe for balance) has been investigated depending on the rate of dose build-up at an average ion current density of 10, 20, and 40 μA/cm2. It has been established that the fatigue life and microhardness of surface layers increase in the entire studied range of dose build-up rates. This seems to be due to the hardening of the surface layers, which resulted from the generation of radiation defects and the irradiation-dynamic effect of fast ions. The sample irradiated by argon ions at the lowest of the selected dose build-up rates j av = 10 μA/cm2 withstands the largest number of cycles to failure.

Parametric scaling of neutral and ion excited state densities in an argon helicon source

NASA Astrophysics Data System (ADS)

McCarren, D.; Scime, E.

2016-04-01

We report measurements of the absolute density and temperature of ion and neutral excited states in an argon helicon source. The excited ion state density, which depends on ion density, electron density, and electron temperature, increases sharply with increasing magnetic field in the source. The neutral argon metastable density measurements are consistent with an increasing ionization fraction with increasing magnetic field strength. The ion temperature shows no evidence of increased heating with increasing magnetic field strength (which has only been observed in helicon sources operating at driving frequencies close to the lower hybrid frequency). The measurements were obtained through cavity ring down spectroscopy, a measurement technique that does not require the target excited state to be metastable or part of a fluorescence scheme; and is therefore applicable to any laser accessible atomic or ionic transition in a plasma.

Application of optical broadband monitoring to quasi-rugate filters by ion-beam sputtering

NASA Astrophysics Data System (ADS)

Lappschies, Marc; Görtz, Björn; Ristau, Detlev

2006-03-01

Methods for the manufacture of rugate filters by the ion-beam-sputtering process are presented. The first approach gives an example of a digitized version of a continuous-layer notch filter. This method allows the comparison of the basic theory of interference coatings containing thin layers with practical results. For the other methods, a movable zone target is employed to fabricate graded and gradual rugate filters. The examples demonstrate the potential of broadband optical monitoring in conjunction with the ion-beam-sputtering process. First-characterization results indicate that these types of filter may exhibit higher laser-induced damage-threshold values than those of classical filters.

Prototype Ge:Ga detectors for the NASA-Ames cooled grating spectrometer

NASA Technical Reports Server (NTRS)

Houck, J. R.

1981-01-01

The detectors were fabricated from a Ge:Ga wafer from Eagle-Pitcher with a room temperature resistivity of approx. 12ohms cm. The wafer is approximately 2 inches in diameter and 0.061 inches thick. The contact material was ion implanted with Boron using 10 to the 14th power ions/sq cm at 25 Kev and 2 x10 to the 14th power ions/sq cm at 50 Kev. The crystal was then sputter-cleaned and metallized first with sputtered Ti and then sputter Au. In addition to the usual infrared measurements of responsivity and noise, measurements were made of the detectors' response to ionizing radiation.

Differential Sputtering Behavior of Pyrolytic Graphite and Carbon-Carbon Composite Under Xenon Bombardment

NASA Technical Reports Server (NTRS)

Williams, John D.; Johnson, Mark L.; Williams, Desiree D.

2003-01-01

A differential sputter yield measurement technique is described, which consists of a quartz crystal monitor that is swept at constant radial distance from a small target region where a high current density xenon ion beam is aimed. This apparatus has been used to characterize the sputtering behavior of various forms of carbon including polycrystalline graphite, pyrolytic graphite, and PVD-infiltrated and pyrolized carbon-carbon composites. Sputter yield data are presented for pyrolytic graphite and carbon-carbon composite over a range of xenon ion energies from 200 eV to 1 keV and angles of incidence from 0 deg (normal incidence) to 60 deg .

A 9700-hour durability test of a five centimeter diameter ion thruster

NASA Technical Reports Server (NTRS)

Nakanishi, S.; Finke, R. C.

1973-01-01

A modified Hughes SIT-5 thrustor has been life-tested at the Lewis Research Center. The final 2700 hours of the test are described with a charted history of thrustor operating parameters and off-normal events. Performance and operating characteristics were nearly constant throughout the test except for neutralizer heater power requirements and accelerator drain current. A post-shutdown inspection revealed sputter erosion of ion chamber components and component flaking of sputtered metal. Several flakes caused beamlet divergence and anomalous grid erosion, causing the test to be terminated. All sputter erosion sources have been identified and promising sputter resistant components are currently being evaluated.

Effect of heat treatment on phase composition and crystal structure of thin WSi2 films on silicon substrates

NASA Astrophysics Data System (ADS)

Biryukov, Y. P.; Dostanko, A. P.; Maltsev, A. A.; Shakhlevich, G. M.

1984-10-01

An experimental study of WSi2 films on silicon substrates with either 111 or 100 orientation was made, for the purpose of determining the effect of annealing by heat treatment on their phase composition and crystal structure. Films of 0.2 micron thickness were deposited at a rate of 0.5 nm/s on a silicon surface which was predecontaminated of SiO2 layers and adsorbate atoms by ion sputtering in one vacuum cycle. Deposition was by condensation, with the substrate held at various temperatures from 390 to 500 C, and then annealed in an argon atmosphere at various temperatures from 700 to 1000 C for 30 min. Subsequent phase analysis at room temperature was performed with a DRON-2 X-ray diffractometer, using a CuK (sub alpha)-radiation source and covering the 20 = 10 to 130 deg range of angles by the Debye-Sherer method, while the surface morphology was examined under an electron microscope.

Conductive, magnetic and structural properties of multilayer films

NASA Astrophysics Data System (ADS)

Kotov, L. N.; Turkov, V. K.; Vlasov, V. S.; Lasek, M. P.; Kalinin, Yu E.; Sitnikov, A. V.

2013-12-01

Composite-semiconductor and composite-dielectric multilayer films were obtained by the ion beam sputtering method in the argon and hydrogen atmospheres with compositions: {[(Co45-Fe45-Zr10)x(Al2O3)y]-[α-Si]}120, {[(Co45-Ta45-Nb10)x(SiO2)y]-[SiO2]}56, {[(Co45-Fe45-Zr10)x(Al2O3)y]-[α-Si:H]}120. The images of surface relief and distribution of the dc current on composite layer surface were obtained with using of atomic force microscopy (AFM). The dependencies of specific electric resistance, ferromagnetic resonance (FMR) fields and width of line on metal (magnetic) phase concentration x and nanolayers thickness of multilayer films were obtained. The characteristics of FMR depend on magnetic interaction among magnetic granules in the composite layers and between the layers. These characteristics depend on the thickness of composite and dielectric or semiconductor nanolayers. The dependences of electric microwave losses on the x and alternating field frequency were investigated.

Continuous wave cavity ring down spectroscopy measurements of velocity distribution functions of argon ions in a helicon plasma.

PubMed

Chakraborty Thakur, Saikat; McCarren, Dustin; Carr, Jerry; Scime, Earl E

2012-02-01

We report continuous wave cavity ring down spectroscopy (CW-CRDS) measurements of ion velocity distribution functions (VDFs) in low pressure argon helicon plasma (magnetic field strength of 600 G, T(e) ≈ 4 eV and n ≈ 5 × 10(11) cm(-3)). Laser induced fluorescence (LIF) is routinely used to measure VDFs of argon ions, argon neutrals, helium neutrals, and xenon ions in helicon sources. Here, we describe a CW-CRDS diagnostic based on a narrow line width, tunable diode laser as an alternative technique to measure VDFs in similar regimes but where LIF is inapplicable. Being an ultra-sensitive, cavity enhanced absorption spectroscopic technique; CW-CRDS can also provide a direct quantitative measurement of the absolute metastable state density. The proof of principle CW-CRDS measurements presented here are of the Doppler broadened absorption spectrum of Ar II at 668.6138 nm. Extrapolating from these initial measurements, it is expected that this diagnostic is suitable for neutrals and ions in plasmas ranging in density from 1 × 10(9) cm(-3) to 1 × 10(13) cm(-3) and target species temperatures less than 20 eV.

Continuous wave cavity ring down spectroscopy measurements of velocity distribution functions of argon ions in a helicon plasma

NASA Astrophysics Data System (ADS)

Chakraborty Thakur, Saikat; McCarren, Dustin; Carr, Jerry; Scime, Earl E.

2012-02-01

We report continuous wave cavity ring down spectroscopy (CW-CRDS) measurements of ion velocity distribution functions (VDFs) in low pressure argon helicon plasma (magnetic field strength of 600 G, Te ≈ 4 eV and n ≈ 5 × 1011 cm-3). Laser induced fluorescence (LIF) is routinely used to measure VDFs of argon ions, argon neutrals, helium neutrals, and xenon ions in helicon sources. Here, we describe a CW-CRDS diagnostic based on a narrow line width, tunable diode laser as an alternative technique to measure VDFs in similar regimes but where LIF is inapplicable. Being an ultra-sensitive, cavity enhanced absorption spectroscopic technique; CW-CRDS can also provide a direct quantitative measurement of the absolute metastable state density. The proof of principle CW-CRDS measurements presented here are of the Doppler broadened absorption spectrum of Ar II at 668.6138 nm. Extrapolating from these initial measurements, it is expected that this diagnostic is suitable for neutrals and ions in plasmas ranging in density from 1 × 109 cm-3 to 1 × 1013 cm-3 and target species temperatures less than 20 eV.

Preliminary Tests of a Paul ion Trap as an Ion Source

NASA Astrophysics Data System (ADS)

Sadat Kiai, S. M.; Zirak, A. R.; Elahi, M.; Adlparvar, S.; Mortazavi, B. N.; Safarien, A.; Farhangi, S.; Sheibani, S.; Alhooie, S.; Khalaj, M. M. A.; Dabirzadeh, A. A.; Ruzbehani, M.; Zahedi, F.

2010-10-01

The paper reports on the design and construction of a Paul ion trap as an ion source by using an impact electron ionization technique. Ions are produced in the trap and confined for the specific time which is then extracted and detected by a Faraday cup. Especial electronic configurations are employed between the end caps, ring electrodes, electron gun and a negative voltage for the detector. This configuration allows a constant low level of pure ion source between the pulsed confined ion sources. The present experimental results are based on the production and confinement of Argon ions with good stability and repeatability, but in principle, the technique can be used for various Argon like ions.

Ion beam microtexturing and enhanced surface diffusion

NASA Technical Reports Server (NTRS)

Robinson, R. S.

1982-01-01

Ion beam interactions with solid surfaces are discussed with particular emphasis on microtexturing induced by the deliberate deposition of controllable amounts of an impurity material onto a solid surface while simultaneously sputtering the surface with an ion beam. Experimental study of the optical properties of microtextured surfaces is described. Measurements of both absorptance as a function of wavelength and emissivity are presented. A computer code is described that models the sputtering and ion reflection processes involved in microtexture formation.

Correlation of process parameters and properties of TiO2 films grown by ion beam sputter deposition from a ceramic target

NASA Astrophysics Data System (ADS)

Bundesmann, Carsten; Lautenschläge, Thomas; Spemann, Daniel; Finzel, Annemarie; Mensing, Michael; Frost, Frank

2017-10-01

The correlation between process parameters and properties of TiO2 films grown by ion beam sputter deposition from a ceramic target was investigated. TiO2 films were grown under systematic variation of ion beam parameters (ion species, ion energy) and geometrical parameters (ion incidence angle, polar emission angle) and characterized with respect to film thickness, growth rate, structural properties, surface topography, composition, optical properties, and mass density. Systematic variations of film properties with the scattering geometry, namely the scattering angle, have been revealed. There are also considerable differences in film properties when changing the process gas from Ar to Xe. Similar systematics were reported for TiO2 films grown by reactive ion beam sputter deposition from a metal target [C. Bundesmann et al., Appl. Surf. Sci. 421, 331 (2017)]. However, there are some deviations from the previously reported data, for instance, in growth rate, mass density and optical properties.

Argon ion pollution of the magnetosphere

NASA Technical Reports Server (NTRS)

Lopez, R. E.

1985-01-01

Construction of a Solar Power Satellite (SPS) would require the injection of large quantities of propellant to transport material from Low Earth Orbit (LEO) to the construction site at Geostationary Earth Orbit (GEO). This injection, in the form of approx 10 to the 32nd power, 2 KeV argon ions (and associated electrons) per SPS, is comparable to the content of the plasmasphere (approx 10 to the 31st power ions). In addition to the mass deposited, this represents a considerable injection of energy. The injection is examined in terms of a simple model for the expansion of the beam plasma. General features of the subsequent magnetospheric convection of the argon are also examined.

A Survey of Xenon Ion Sputter Yield Data and Fits Relevant to Electric Propulsion Spacecraft Integration

NASA Technical Reports Server (NTRS)

Yim, John T.

2017-01-01

A survey of low energy xenon ion impact sputter yields was conducted to provide a more coherent baseline set of sputter yield data and accompanying fits for electric propulsion integration. Data uncertainties are discussed and different available curve fit formulas are assessed for their general suitability. A Bayesian parameter fitting approach is used with a Markov chain Monte Carlo method to provide estimates for the fitting parameters while characterizing the uncertainties for the resulting yield curves.

Synthesis, Characterization and Optical Constants of Silicon Oxycarbide

NASA Astrophysics Data System (ADS)

Memon, Faisal Ahmed; Morichetti, Francesco; Abro, Muhammad Ishaque; Iseni, Giosue; Somaschini, Claudio; Aftab, Umair; Melloni, Andrea

2017-03-01

High refractive index glasses are preferred in integrated photonics applications to realize higher integration scale of passive devices. With a refractive index that can be tuned between SiO2 (1.45) and a-SiC (3.2), silicon oxycarbide SiOC offers this flexibility. In the present work, silicon oxycarbide thin films from 0.1 - 2.0 μm thickness are synthesized by reactive radio frequency magnetron sputtering a silicon carbide SiC target in a controlled argon and oxygen environment. The refractive index n and material extinction coefficient k of the silicon oxycarbide films are acquired with variable angle spectroscopic ellipsometry over the UV-Vis-NIR wavelength range. Keeping argon and oxygen gases in the constant ratio, the refractive index n is found in the range from 1.41 to 1.93 at 600 nm which is almost linearly dependent on RF power of sputtering. The material extinction coefficient k has been estimated to be less than 10-4 for the deposited silicon oxycarbide films in the visible and near-infrared wavelength regions. Morphological and structural characterizations with SEM and XRD confirms the amorphous phase of the SiOC films.

Relationship Between Crystalline Structure and Hardness of Ti-Si-N-O Coatings Fabricated by dc Sputtering

NASA Astrophysics Data System (ADS)

García-González, Leandro; Hernández-Torres, Julián; Mendoza-Barrera, Claudia; Meléndez-Lira, Miguel; García-Ramírez, Pedro J.; Martínez-Castillo, Jaime; Sauceda, Ángel; Herrera-May, Agustin L.; Muñoz Saldaña, Juan; Espinoza-Beltrán, Francisco J.

2008-08-01

Ti-Si-N-O coatings were deposited on AISI D2 tool steel and silicon substrates by dc reactive magnetron co-sputtering using a target of Ti-Si with a constant area ratio of 0.2. The substrate temperature was 400 °C and reactive atmosphere of nitrogen and argon. For all samples, argon flow was maintained constant at 25 sccm, while the flow of the nitrogen was varied to analyze the structural changes related to chemical composition and resistivity. According to results obtained by x-ray diffraction and stoichiometry calculations by x-ray energy dispersive spectroscopy the Ti-Si-N-O coatings contain two solid solutions. The higher crystalline part corresponds to titanium oxynitrure. Hardness tests on the coatings were carried out using the indentation work model and the hardness value was determined. Finally, the values of hardness were corroborated by nanoindentation test, and values of Young’s modulus and elastic recovery were discussed. We concluded that F2TSN sample ( F Ar = 25 sccm, F N = 5 sccm, P = 200 W, and P W = 8.9 × 10-3 mbar) presented the greatest hardness and the lowest resistivity values, due to its preferential crystalline orientation.

High-acoustic-impedance tantalum oxide layers for insulating acoustic reflectors.

PubMed

Capilla, Jose; Olivares, Jimena; Clement, Marta; Sangrador, Jesús; Iborra, Enrique; Devos, Arnaud

2012-03-01

This work describes the assessment of the acoustic properties of sputtered tantalum oxide films intended for use as high-impedance films of acoustic reflectors for solidly mounted resonators operating in the gigahertz frequency range. The films are grown by sputtering a metallic tantalum target under different oxygen and argon gas mixtures, total pressures, pulsed dc powers, and substrate biases. The structural properties of the films are assessed through infrared absorption spectroscopy and X-ray diffraction measurements. Their acoustic impedance is assessed by deriving the mass density from X-ray reflectometry measurements and the acoustic velocity from picosecond acoustic spectroscopy and the analysis of the frequency response of the test resonators.

The Argon Geochronology Experiment (AGE)

NASA Technical Reports Server (NTRS)

Swindle, T. D.; Bode, R.; Fennema, A.; Chutjian, A.; MacAskill, J. A.; Darrach, M. R.; Clegg, S. M.; Wiens, R. C.; Cremers, D.

2006-01-01

This viewgraph presentation reviews the Argon Geochronology Experiment (AGE). Potassium-Argon dating is shown along with cosmic ray dating exposure. The contents include a flow diagram of the Argon Geochronology Experiment, and schematic diagrams of the mass spectrometer vacuum system, sample manipulation mechanism, mineral heater oven, and the quadrupole ion trap mass spectrometer. The Laser-Induced Breakdown Spectroscopy (LIBS) Operation with elemental abundances is also described.

Effects of oxygen concentration on atmospheric pressure dielectric barrier discharge in Argon-Oxygen Mixture

NASA Astrophysics Data System (ADS)

Li, Xuechun; Li, Dian; Wang, Younian

2016-09-01

A dielectric barrier discharge (DBD) can generate a low-temperature plasma easily at atmospheric pressure and has been investigated for applications in trials in cancer therapy, sterilization, air pollution control, etc. It has been confirmed that reactive oxygen species (ROS) play a key role in the processes. In this work, we use a fluid model to simulate the plasma characteristics for DBD in argon-oxygen mixture. The effects of oxygen concentration on the plasma characteristics have been discussed. The evolution mechanism of ROS has been systematically analyzed. It was found that the ground state oxygen atoms and oxygen molecular ions are the dominated oxygen species under the considered oxygen concentrations. With the oxygen concentration increasing, the densities of electrons, argon atomic ions, resonance state argon atoms, metastable state argon atoms and excited state argon atoms all show a trend of decline. The oxygen molecular ions density is high and little influenced by the oxygen concentration. Ground state oxygen atoms density tends to increase before falling. The ozone density increases significantly. Increasing the oxygen concentration, the discharge mode begins to change gradually from the glow discharge mode to Townsend discharge mode. Project supported by the National Natural Science Foundation of China (Grant No. 11175034).

Time-of-flight secondary ion mass spectrometry studies of cluster ion analysis for semiconductors and diffusion of manganese in gallium arsenide at low temperatures

NASA Astrophysics Data System (ADS)

Goacher, Robyn Elizabeth

Secondary Ion Mass Spectrometry (SIMS) is an established method for the quantitative analysis of dopants in semiconductors. The quasi-parallel mass acquisition of Time-of-Flight SIMS, along with the development of polyatomic primary ions, have rapidly increased the use of SIMS for analysis of organic and biological specimens. However, the advantages and disadvantages of using cluster primary ions for quantitative analysis of inorganic materials are not clear. The research described in this dissertation investigates the consequences of using polyatomic primary ions for the analysis of inorganic compounds in ToF-SIMS. Furthermore, the diffusion of Mn in GaAs, which is important in Spintronic material applications such as spin injection, is also studied by quantitative ToF-SIMS depth profiling. In the first portion of this work, it was discovered that primary ion bombardment of pre-sputtered compound semiconductors GaAs and InP for the purpose of spectral analysis resulted in the formation of cluster secondary ions, as well as atomic secondary ions (Chapter 2). In particular, bombardment using a cluster primary ion such as Bi3q + or C60q+ resulted in higher yields of high-mass cluster secondary ions. These cluster secondary ions did not have bulk stoichiometry, "non-stoichiometric", in contrast to the paradigm of stoichiometric cluster ions generated from salts. This is attributed to the covalent bonding of the compound semiconductors, as well as to preferential sputtering. The utility of high-mass cluster secondary ions in depth profiling is also discussed. Relative sensitivity factors (RSFs) calculated for ion-implanted Fe and Mn samples in GaAs also exhibit differences based on whether monatomic or polyatomic primary ions are utilized (Chapter 3). These RSFs are important for the quantitative conversion of intensity to concentration. When Bi 32+ primary ions are used for analysis instead of Bi + primary ions, there is a significantly higher proportion of Mn and Fe ions present in the spectra, as referenced to the matrix species. The magnitude of this effect differs depending on the sputtering ion, Cs or C60. The use of C60cluster primary ions for depth profiling of GaAs is also investigated (Chapter 4). In particular, for quantitative depth profiling, parameters such as depth resolution, ion and sputter yields, and relative sensitivity factors are pertinent to profiling thin layered structures quantitatively and quickly. C60 sputtering is compared to Cs sputtering in all of these aspects. It is found that 10 keV C60+ is advantageous for the analysis of metals (such as Au contacts on Si) but that previously reported roughness problems prohibit successful analysis in Si. For Al delta layers and quantum wells in GaAs, C60 q+ sputtering induced very little roughness in the sample, and resulted in high ion yields and excellent signal-to-noise as compared to Cs+ sputtering. However, the depth resolution of C60 is at best equivalent to 1 keV Cs+ and does not extend into the sub 2-nm range. Furthermore, C60 sputtering results in significant carbon implantation. In the second portion of this work, quantitative ToF-SIMS depth profiling was used to evaluate the diffusion of Mn into GaAs. Samples were prepared by Molecular Beam Epitaxy in the department of Physics. Mn diffusion from MnAs was investigated first, and Mn diffusion from layered epitaxial structures of GaAs / Ga1-xMnxAs / GaAs was investigated second. Diffusion experiments were conducted by annealing portions of the samples in sealed glass ampoules at low temperatures (200-400°C). Different sputtering rates were measured for MnAs and GaAs and the measured depth profiles were corrected for these effects. RSFs measured for Mn ion-implanted standards were used to calibrate the intensity scale. For diffusion from MnAs, thin MnAs layers resulted in no measurable changes except in the surface transient. For thick MnAs layers, it was determined that substantial loss of As occurred at 400°C, resulting in severe sample roughening, which inhibited proper SIMS analysis. Results for the diffusion of Mn out of a thick buried layer of Ga1-xMnxAs show that annealing induces diffusion of Mn species from the Ga1-xMnxAs layer into the neighboring GaAs with an activation energy of 0.69+/-0.09 eV. This results in doping of the GaAs layer, which is detrimental to spin injection for Spintronics devices.

Contamination control and plume assessment of low-energy thrusters

NASA Technical Reports Server (NTRS)

Scialdone, John J.

1993-01-01

Potential contamination of a spacecraft cryogenic surface by a xenon (Xe) ion generator was evaluated. The analysis involves the description of the plume exhausted from the generator with its relative component fluxes on the spacecraft surfaces, and verification of the conditions for condensation, adsorption, and sputtering at those locations. The data describing the plume fluxes and their effects on surfaces were obtained from two sources: the tests carried out with the Xe generator in a small vacuum chamber to indicate deposits and sputter on monitor slides; and the extensive tests with a mercury (Hg) ion thruster in a large vacuum chamber. The Hg thruster tests provided data on the neutrals, on low-energy ion fluxes, on high-energy ion fluxes, and on sputtered materials at several locations within the plume.

Sputtering of sulfur by kiloelectronvolt ions - Application to the magnetospheric plasma interaction with Io

NASA Technical Reports Server (NTRS)

Chrisey, D. B.; Johnson, R. E.; Phipps, J. A.; Mcgrath, M. A.; Boring, J. W.

1987-01-01

Accurate measurements of the yields, mass spectra, and energy spectra of ejected sulfur are presented based on vapor deposits of sulfur at temperatures and ion energies relevant to the plasma interaction with the surface of Io. The measured sputtering yields are much lower than previous estimates for room temperature sulfur films, but are comparable to previous measurements of low-temperature keV ion sputtering of SO2. Results suggest that if ions reach the surface of Io its atmosphere will have a nonnegligible sulfur component which is primarily S2. Comparison of injection rates determined for sulfur with those for SO2 indicates that injection from sulfur deposits contributes 13 percent to the total mass injection rate of about 2-3 x 10 to the 29th amu/sec.

Multilayer coating of optical substrates by ion beam sputtering

NASA Astrophysics Data System (ADS)

Daniel, M. V.; Demmler, M.

2017-10-01

Ion beam sputtering is well established in research and industry, despite its relatively low deposition rates compared to electron beam evaporation. Typical applications are coatings of precision optics, like filters, mirrors and beam splitter. Anti-reflective or high-reflective multilayer stacks benefit from the high mobility of the sputtered particles on the substrate surface and the good mechanical characteristics of the layers. This work gives the basic route from single layer optimization of reactive ion beam sputtered Ta2O5 and SiO2 thin films towards complex multilayer stacks for high-reflective mirrors and anti-reflective coatings. Therefore films were deposited using different oxygen flow into the deposition chamber Afterwards, mechanical (density, stress, surface morphology, crystalline phases) and optical properties (reflectivity, absorption and refractive index) were characterized. These knowledge was used to deposit a multilayer coating for a high reflective mirror.

An empirical model for ion formation from polymer surfaces during analysis by secondary ion mass spectrometry

NASA Astrophysics Data System (ADS)

Leggett, Graham J.; Vickerman, John C.

1992-12-01

Some of the models that have been proposed to account for ion formation during sputtering are reviewed. Particular attention is paid to models describing polyatomic ion formation. Aspects of these models that are relevant to ion formation from molecular materials are discussed. Reports describing the sputtering of polymeric materials are reviewed, and the bearing of recent tandem studies on attempts to formulate a model for ion formation from polymer materials is discussed. Some of the characteristics that a suitable model would possess are identified from the experimental data.

Evaluation of left ventricular assist device pump bladders cast from ion-sputtered polytetrafluorethylene mandrels

NASA Technical Reports Server (NTRS)

1982-01-01

A highly thromboresistant blood contacting interface for use in implanatable blood pump is investigated. Biomaterials mechanics, dynamics, durability, surface morphology, and chemistry are among the critical consideration pertinent to the choice of an appropriate blood pump bladder material. The use of transfer cast biopolymers from ion beam textured surfaces is investigated to detect subtle variations in blood pump surface morphology using Biomer as the biomaterial of choice. The efficacy of ion beam sputtering as an acceptable method of fabricating textured blood interfaces is evaluated. Aortic grafts and left ventricular assist devices were implanted in claves; the blood interfaces were fabricated by transfer casting methods from ion beam textured polytetrafluorethylene mandrels. The mandrels were textured by superimposing a 15 micron screen mesh; ion sputtering conditions were 300 volts beam energy, 40 to 50 mA beam, and a mandrel to source distance of 25 microns.

A Fast-Ion Source for LAPD

NASA Astrophysics Data System (ADS)

Zhao, L.; Boehmer, H.; Edrich, D.; Heidbrink, W. W.; McWilliams, R.; Leneman, D.

2002-11-01

To measure the fast-ion transport as a function of gyroradius, a 3-cm diameter, 17 MHz, ˜ 80 W, ˜ 3 mA, argon source is under development for use in the LArge Plasma Device (LAPD). In tests on the Irvine Mirror, the source performs reliably when oriented either parallel to the magnetic field or at an oblique angle and in either a CW or pulsed mode of operation. A radial energy analyzer measures the profile of the 200-500 eV beam. Laser-induced fluorescence (LIF) of cold 3d^2G_9/2 argon metastables excited by the source is readily measured but the hot argon ions in the beam itself are more difficult to detect. In preliminary tests on LAPD, the source operated successfully. Planned physics experiments include measurements of collisional fast-ion diffusion and fluctuation-induced transport.

Influence of argon and oxygen on charge-state-resolved ion energy distributions of filtered aluminum arcs

NASA Astrophysics Data System (ADS)

Rosén, Johanna; Anders, André; Mráz, Stanislav; Atiser, Adil; Schneider, Jochen M.

2006-06-01

The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range of 0.5-8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow charge-state distribution as well as a narrow IED. These data may enable tailoring thin film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.

Tuning silver ion release properties in reactively sputtered Ag/TiOx nanocomposites

NASA Astrophysics Data System (ADS)

Xiong, J.; Ghori, M. Z.; Henkel, B.; Strunskus, T.; Schürmann, U.; Deng, M.; Kienle, L.; Faupel, F.

2017-07-01

Silver/titania nanocomposites with strong bactericidal effects and good biocompatibility/environmental safety show a high potential for antibacterial applications. Tailoring the silver ion release is thus highly promising to optimize the antibacterial properties of such coatings and to preserve biocompatibility. Reactive sputtering is a fast and versatile method for the preparation of such Ag/TiOx nanocomposites coatings. The present work is concerned with the influence of sputter parameters on the surface morphology and silver ion release properties of reactively sputtered Ag/TiOx nanocomposites coatings showing a silver nanoparticle size distribution in the range from 1 to 20 nm. It is shown that the silver ion release rate strongly depends on the total pressure: the coatings prepared at lower pressure present a lower but long-lasting release behavior. The much denser structure produced under these conditions reduces the transport of water molecules into the coating. In addition, the influence of microstructure and thickness of titanium oxide barriers on the silver ion release were investigated intensively. Moreover, for the coatings prepared at high total pressure, it was demonstrated that stable and long-lasting silver release can be achieved by depositing a barrier with a high rate. Nanocomposites produced under these conditions show well controllable silver ion release properties for applications as antibacterial coatings.

Study of thickness dependent sputtering in gold thin films by swift heavy ion irradiation

NASA Astrophysics Data System (ADS)

Dash, P.; Sahoo, P. K.; Solanki, V.; Singh, U. B.; Avasthi, D. K.; Mishra, N. C.

2015-12-01

Gold thin films of varying thickness (10-100 nm) grown on silica substrates by e-beam evaporation method were irradiated by 120 MeV Au ions at 3 × 1012 and 1 × 1013 ions cm-2 fluences. Irradiation induced modifications of these films were probed by glancing angle X-ray diffraction (GAXRD), atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS) and surface enhanced Raman scattering (SERS). Irradiation didn't affect the structure, the lattice parameter or the crystallite size, but modified the texturing of grains from [1 1 1] to [2 2 0]. RBS indicated thickness dependent sputtering on irradiation. The sputtering yield was found to decrease with increasing thickness. AFM indicated increase of roughness with increasing irradiation fluence for films of all thickness. In agreement with the AFM observation, the gold nanostructures on the surface of 20 nm thick film were found to increase the SERS signal of acridine orange dye attached to these structures. The SERS peaks were amplified by many fold with increasing ion fluence. The effect of 120 MeV Au ion irradiation on the grain texture, surface morphology and SERS activity in addition to the thickness dependent sputtering in gold thin films are explained by the thermal spike model of ion-matter interaction.

Study of electronic sputtering of CaF2 thin films

NASA Astrophysics Data System (ADS)

Pandey, Ratnesh K.; Kumar, Manvendra; Khan, Saif A.; Kumar, Tanuj; Tripathi, Ambuj; Avasthi, D. K.; Pandey, Avinash C.

2014-01-01

In the present work thin films of CaF2 deposited on Si substrate by electron beam evaporation have been investigated for swift heavy ions induced sputtering and surface modifications. Glancing angle X-ray Diffraction (GAXRD) measurements show that the pristine films are polycrystalline in nature and the grain size increases with increase in film thickness. Rutherford backscattering spectrometry (RBS) of pristine as well as irradiated films was performed to determine the sputter yield of CaF2 and a decrease in sputter yield has been observed with increase in film thickness. Thermal spike model has been applied to explain this. The confinement of energy in the grains having size smaller than the electron mean free path (λ) results in a higher sputtering yield. Atomic force microscopy (AFM) studies of irradiated CaF2 thin films show formation of cracks on film surface at a fluence of 5 × 1012 ions/cm2. Also RBS results confirm the removal of film from the surface and more exposure of substrate with increasing dose of ions.

Computer simulation of sputtering induced by swift heavy ions

NASA Astrophysics Data System (ADS)

Kucharczyk, P.; Füngerlings, A.; Weidtmann, B.; Wucher, A.

2018-07-01

New experimental results regarding the mass and charge state distribution of material sputtered under irradiation with swift heavy ions suggest fundamental differences between the ejection mechanisms under electronic and nuclear sputtering conditions. In order to illustrate the difference, computer simulations based on molecular dynamics were performed to model the surface ejection process of atoms and molecules induced by a swift heavy ion track. In a first approach, the track is homogeneously energized by assigning a fixed energy to each atom with randomly oriented direction of motion within a cylinder of a given radius around the projectile ion trace. The remainder of the target crystal is assumed to be at rest, and the resulting lattice dynamics is followed by molecular dynamics. The resulting sputter yield is calculated as a function of track radius and energy and compared to corresponding experimental data in order to find realistic values for the effective deposited lattice energy density. The sputtered material is analyzed with respect to emission angle and energy as well as depth of origin. The results are compared to corresponding data from keV sputter simulations. As a second step of complexity, the homogeneous and monoenergetic lattice energization is replaced by a starting energy distribution described by a local lattice temperature. As a first attempt, the respective temperature is assumed constant within the track, and the results are compared with those obtained from monoenergetic energization with the same average energy per atom.

Technical use of compact micro-onde devicesa)

NASA Astrophysics Data System (ADS)

Sortais, P.; Lamy, T.; Médard, J.; Angot, J.; Sudraud, P.; Salord, O.; Homri, S.

2012-02-01

Due to the very small size of a COMIC (Compact MIcrowave and Coaxial) device [P. Sortais, T. Lamy, J. Médard, J. Angot, L. Latrasse, and T. Thuillier, Rev. Sci. Instrum. 81, 02B31 (2010), 10.1063/1.3272878] it is possible to install such plasma or ion source inside very different technical environments. New applications of such a device are presented, mainly for industrial applications. We have now designed ion sources for highly focused ion beam devices, ion beam machining ion guns, or thin film deposition machines. We will mainly present new capabilities opened by the use of a multi-beam system for thin film deposition based on sputtering by medium energy ion beams. With the new concept of multi-beam sputtering (MBS), it is possible to open new possibilities concerning the ion beam sputtering (IBS) technology, especially for large size deposition of high uniformity thin films. By the use of multi-spots of evaporation, each one corresponding to an independent tuning of an individual COMIC ion source, it will be very easy to co-evaporate different components.

Measurement of the electron and ion temperatures by the x-ray imaging crystal spectrometer on joint Texas experimental tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, W.; Chen, Z. Y., E-mail: zychen@hust.edu.cn; Huang, D. W.

An x-ray imaging crystal spectrometer has been developed on joint Texas experimental tokamak for the measurement of electron and ion temperatures from the K{sub α} spectra of helium-like argon and its satellite lines. A two-dimensional multi-wire proportional counter has been applied to detect the spectra. The electron and ion temperatures have been obtained from the Voigt fitting with the spectra of helium-like argon ions. The profiles of electron and ion temperatures show the dependence on electron density in ohmic plasmas.

Retention of Sputtered Molybdenum on Ion Engine Discharge Chamber Surfaces

NASA Technical Reports Server (NTRS)

Sovey, James S.; Dever, Joyce A.; Power, John L.

2001-01-01

Grit-blasted anode surfaces are commonly used in ion engines to ensure adherence of sputtered coatings. Next generation ion engines will require higher power levels, longer operating times, and thus there will likely be thicker sputtered coatings on their anode surfaces than observed to date on 2.3 kW-class xenon ion engines. The thickness of coatings on the anode of a 10 kW, 40-centimeter diameter thruster, for example, may be 22 micrometers or more after extended operation. Grit-blasted wire mesh, titanium, and aluminum coupons were coated with molybdenum at accelerated rates to establish coating stability after the deposition process and after thermal cycling tests. These accelerated deposition rates are roughly three orders of magnitude more rapid than the rates at which the screen grid is sputtered in a 2.3 kW-class, 30-centimeter diameter ion engine. Using both RF and DC sputtering processes, the molybdenum coating thicknesses ranged from 8 to 130 micrometers, and deposition rates from 1.8 micrometers per hour to 5.1 micrometers per hour. In all cases, the molybdenum coatings were stable after the deposition process, and there was no evidence of spalling of the coatings after 20 cycles from about -60 to +320 C. The stable, 130 micrometer molybdenum coating on wire mesh is 26 times thicker than the thickest coating found on the anode of a 2.3 kW, xenon ion engine that was tested for 8200 hr. Additionally, this coating on wire mesh coupon is estimated to be a factor of greater than 4 thicker than one would expect to obtain on the anode of the next generation ion engine which may have xenon throughputs as high as 550 kg.

Heavy particle transport in sputtering systems

NASA Astrophysics Data System (ADS)

Trieschmann, Jan

2015-09-01

This contribution aims to discuss the theoretical background of heavy particle transport in plasma sputtering systems such as direct current magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS), or multi frequency capacitively coupled plasmas (MFCCP). Due to inherently low process pressures below one Pa only kinetic simulation models are suitable. In this work a model appropriate for the description of the transport of film forming particles sputtered of a target material has been devised within the frame of the OpenFOAM software (specifically dsmcFoam). The three dimensional model comprises of ejection of sputtered particles into the reactor chamber, their collisional transport through the volume, as well as deposition of the latter onto the surrounding surfaces (i.e. substrates, walls). An angular dependent Thompson energy distribution fitted to results from Monte-Carlo simulations is assumed initially. Binary collisions are treated via the M1 collision model, a modified variable hard sphere (VHS) model. The dynamics of sputtered and background gas species can be resolved self-consistently following the direct simulation Monte-Carlo (DSMC) approach or, whenever possible, simplified based on the test particle method (TPM) with the assumption of a constant, non-stationary background at a given temperature. At the example of an MFCCP research reactor the transport of sputtered aluminum is specifically discussed. For the peculiar configuration and under typical process conditions with argon as process gas the transport of aluminum sputtered of a circular target is shown to be governed by a one dimensional interaction of the imposed and backscattered particle fluxes. The results are analyzed and discussed on the basis of the obtained velocity distribution functions (VDF). This work is supported by the German Research Foundation (DFG) in the frame of the Collaborative Research Centre TRR 87.

Effects of polycrystallinity in nano patterning by ion-beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Sun Mi; Kim, J.-S., E-mail: jskim@sm.ac.kr; Yoon, D.

Employing graphites with distinctly different mean grain sizes, we study the effects of polycrystallinity on the pattern formation by ion-beam sputtering. The grains influence the growth of the ripples in a highly anisotropic fashion; both the mean uninterrupted ripple length along the ridges and the surface width depend on the mean size of the grains, which is attributed to the large sputter yield at the grain boundary compared with that on the terrace. In contrast, the ripple wavelength does not depend on the mean size of the grains, indicating that the mass transport across the grain boundaries should efficiently proceedmore » by both thermal diffusion and ion-induced processes.« less

Heavy ion irradiation of crystalline water ice. Cosmic ray amorphisation cross-section and sputtering yield

NASA Astrophysics Data System (ADS)

Dartois, E.; Augé, B.; Boduch, P.; Brunetto, R.; Chabot, M.; Domaracka, A.; Ding, J. J.; Kamalou, O.; Lv, X. Y.; Rothard, H.; da Silveira, E. F.; Thomas, J. C.

2015-04-01

Context. Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims: We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. Methods: We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results: The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions: The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice sputtering rates compete with the UV photodesorption yields reported in the literature. The prevalence of direct cosmic ray sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices. Experiments performed at the Grand Accélérateur National d'Ions Lourds (GANIL) Caen, France. Part of this work has been financed by the French INSU-CNRS programme "Physique et Chimie du Milieu Interstellaire" (PCMI) and the ANR IGLIAS.

Sources of Sodium in the Lunar Exosphere: Modeling Using Ground-Based Observations of Sodium Emission and Spacecraft Data of the Plasma

NASA Technical Reports Server (NTRS)

Sarantos, Menelaos; Killen, Rosemary M.; Sharma, A. Surjalal; Slavin, James A.

2009-01-01

Observations of the equatorial lunar sodium emission are examined to quantify the effect of precipitating ions on source rates for the Moon's exospheric volatile species. Using a model of exospheric sodium transport under lunar gravity forces, the measured emission intensity is normalized to a constant lunar phase angle to minimize the effect of different viewing geometries. Daily averages of the solar Lyman alpha flux and ion flux are used as the input variables for photon-stimulated desorption (PSD) and ion sputtering, respectively, while impact vaporization due to the micrometeoritic influx is assumed constant. Additionally, a proxy term proportional to both the Lyman alpha and to the ion flux is introduced to assess the importance of ion-enhanced diffusion and/or chemical sputtering. The combination of particle transport and constrained regression models demonstrates that, assuming sputtering yields that are typical of protons incident on lunar soils, the primary effect of ion impact on the surface of the Moon is not direct sputtering but rather an enhancement of the PSD efficiency. It is inferred that the ion-induced effects must double the PSD efficiency for flux typical of the solar wind at 1 AU. The enhancement in relative efficiency of PSD due to the bombardment of the lunar surface by the plasma sheet ions during passages through the Earth's magnetotail is shown to be approximately two times higher than when it is due to solar wind ions. This leads to the conclusion that the priming of the surface is more efficiently carried out by the energetic plasma sheet ions.

A facility to study the particles released by ion sputtering process

NASA Astrophysics Data System (ADS)

de Angelis, E.; di Lellis, A. M.; Vannaroni, G.; Orsini, S.; Mangano, V.; Milillo, A.; Massetti, S.; Mura, A.; Vertolli, N.

2007-08-01

Research on the planetary surface erosion and planetary evolution could be enriched with the detection of the escaping material, in terms of energy and direction, caused by ions sputtering. A complete study of emitted neutral distribution from which infers the processes occurring on the impacted surface requires dedicated instrumentation, tailored on the peculiarity on the low energy profile of the sputtered signal. We propose a comprehensive facility at INAF/IFSI in Rome intended to provide the opportunity to investigate the interaction of selectable ion beam with planetary analogues through the detection of sputtered neutral atoms. The laboratory is equipped with a high volume UHV chamber, ion selectable sources in the range 0 to 10 keV, a set of 3D sample/sensor orientation motion actuation motors down to 1/100 deg resolution. The laboratory will support a set of neutral sensor heads sets derived from the Emitted for Low Energetic Neutral Atoms (ELENA) instrument under development for the ESA BepiColombo Mercury mission able to detect neutral atoms (few eV-up to 5 keV).

An exploratory study of recycled sputtering and CsF2- current enhancement for AMS

NASA Astrophysics Data System (ADS)

Zhao, X.-L.; Charles, C. R. J.; Cornett, R. J.; Kieser, W. E.; MacDonald, C.; Kazi, Z.; St-Jean, N.

2016-01-01

The analysis of 135Cs/Cs ratios at levels below 10-12 by accelerator mass spectrometry (AMS) would preferably use commonly available negative ion injection systems. The sputter ion sources in these injectors should ideally produce currents of Cs- or Cs-containing molecular anions approaching μA levels from targets containing mg quantities of Cs. However, since Cs is the most electro-positive stable element in nature with a low electron affinity, the generation of large negative atomic, or molecular beams containing Cs, has been very challenging. In addition, the reduction of the interferences from the 135Ba isobar and the primary 133Cs+ beam used for sputtering are also necessary. The measurement of a wide range of the isotope ratios also requires the ion source memory of previous samples be minimized. This paper describes some progresses towards a potential solution of all these problems by recycled sputtering using fluorinating targets of PbF2 with mg CsF mixed in. The problems encountered indicate that considerable further studies and some redesign of the present ion sources will be desirable.

Growth and characterization of zirconium oxynitride films prepared by reactive direct current magnetron sputtering

NASA Astrophysics Data System (ADS)

Venkataraj, S.; Kappertz, O.; Jayavel, R.; Wuttig, M.

2002-09-01

Thin films of zirconium oxynitrides have been deposited onto Si(100) substrates at room temperature by reactive dc magnetron sputtering of a metallic Zr target in an argon-oxygen-nitrogen atmosphere. To prepare oxynitride films the sum of the O2 and N2 flow was kept at 3.5 sccm, while the relative nitrogen content of this mixture was changed stepwise from 0% to 100%. The film structure was determined by x-ray diffraction, while x-ray reflectometry was employed to determine the thickness, density, and surface roughness of the films. The optical properties have been studied by spectroscopic reflectance measurements. X-ray diffraction (XRD) determines that the as-deposited films are crystalline and do not change their monoclinic ZrO2 crystal structure even for nitrogen flows up to 80%. For pure argon-nitrogen sputtering, on the contrary, cubic zirconium nitride (ZrN) has been formed. Nevertheless, even though the crystal structure does not change with increasing nitrogen flow up to 80%, there is clear evidence from nitrogen incorporation from Rutherford backscattering experiments, optical spectroscopy, XRD, and x-ray reflectometry. The latter technique determines that the film density increases from 5.2 to 5.8 g/cm3 with increasing nitrogen flow from 0% to 80%. Simultaneously, the rate of sputtering increases from 0.17 to 0.6 m/s, while the film roughness decreases upon increasing N2 flow. Optical spectroscopy measurements of the film reflectance confirm that fully transparent films can be prepared up to a nitrogen flow of 80%. For these films, the band gap decreases from 4.52 to 3.59 eV with increasing N2 flow, while the refractive index at 650 nm simultaneously increases from 2.11 to 2.26. For 100% N2 flow, i.e., without any oxygen, films with a metallic reflectance are obtained.

Influences of the residual argon gas and thermal annealing on Ta2O5 and SiO2 thin film filters

NASA Astrophysics Data System (ADS)

Liu, Wen-Jen; Chen, Chih-Min; Lai, Yin-Chieh

2005-04-01

Ion beam assisted deposition (IBAD) technique had widely used for improving stacking density and atomic mobility of thin films in many applications, especially adopted in optical film industries. Tantalum pentaoxide (Ta2O5) and silicon oxides (SiO2) optical thin films were deposited on the quartz glass substrate by using argon ion beam assisted deposition, and the influences of the residual argon gas and thermal annealing processes on the optical property, stress, compositional and microstructure evolution of the thin films were investigated in this study. Ta2O5 thin films were analyzed by XPS indicated that the ratio value of oxygen to tantalum was insufficient, at the same time, the residual argon gas in the thin films might result in film and device instabilities. Adopting oxygen-thermal annealing treatment at the temperature of 425°C, the thin films not only decreased the residual argon gas and the surface roughness, but also provided the sufficient stoichiometric ratio. Simultaneously, microstructure examination indicated few nano-crystallized structures and voids existed in Ta2O5 thin films, and possessed reasonable refractive index and lower extinction coefficient. By the way, we also suggested the IBAD system using the film compositional gas ion beam to replace the argon ion beam for assisting deposited optical films. The designed (HL)6H6LH(LH)6 multi-layers indicated higher insertion loss than the designed (HL)68H(LH)6 multi-layers. Therefore, using the high refractive index as spacer material represented lower insertion loss.

Caesium sputter ion source compatible with commercial SIMS instruments

NASA Astrophysics Data System (ADS)

Belykh, S. F.; Palitsin, V. V.; Veryovkin, I. V.; Kovarsky, A. P.; Chang, R. J. H.; Adriaens, A.; Dowsett, M.; Adams, F.

2006-07-01

A simple design for a caesium sputter cluster ion source compatible with commercially available secondary ion mass spectrometers is reported. This source has been tested with the Cameca IMS 4f instrument using the cluster Si n- and Cu n- ions, and will shortly be retrofitted to the floating low energy ion gun (FLIG) of the type used on the Cameca 4500/4550 quadruple instruments. Our experiments with surface characterization and depth profiling conducted to date demonstrate improvements of analytical capabilities of the SIMS instrument due to the non-additive enhancement of secondary ion emission and shorter ion ranges of polyatomic projectiles compared to atomic ions with the same impact energy.

Sputtering of ices in the outer solar system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, R.E.

1996-01-01

Exploration of the outer solar system has led to studies in a new area of physics: electronically induced sputtering of low-temperature, condensed-gas solids (ices). Many of the icy bodies in the outer solar system were found to be bombarded by relatively intense fluxes of ions and electrons, causing both changes in their optical reflectance and ejection (sputtering) of molecules from their surfaces. The small cohesive energies of the condensed-gas solids afford relatively large sputtering rates from the electronic excitations produced in the solid by fast ions and electrons. Such sputtering produces an ambient gas about an icy body, often themore » source of the local plasma. This colloquium outlines the physics of the sputtering of ices and its relevance to several outer-solar-system phenomena: the sputter-produced plasma trapped in Saturn{close_quote}s magnetosphere; the O{sub 2} atmosphere on Europa; and optical absorption features such as SO{sub 2} in the surface of Europa and O{sub 2} and, possibly, O{sub 3} in the surface of Ganymede. {copyright} {ital 1996 The American Physical Society.}« less

Method and apparatus for sputtering utilizing an apertured electrode and a pulsed substrate bias

NASA Technical Reports Server (NTRS)

Przybyszewski, J. S.; Shaltens, R. K. (Inventor)

1973-01-01

The method and equipment used for sputtering by use of an apertured electrode and a pulsed substrate bias are discussed. The technique combines the advantages of ion plating with the versatility of a radio frequency sputtered source. Electroplating is accomplished by passing a pulsed high voltage direct current to the article being plated during radio frequency sputtering.

Features of nanostructures sputtering

NASA Astrophysics Data System (ADS)

Kapustin, S. N.; Matveev, V. I.; Eseev, M. K.

2017-09-01

The research of ion sputtering of nanoparticles is interesting both from the fundamental point of view - for researching the interior structure of nanoobjects, and the economical one - nanostructures often play the role of functional supplements in composite materials under the radiation pressure. This process should be taken into account while creating objects decorated by nanoclusters during ion implantation. Polyatomic clusters obtained as a result of ion bombing could be used as nanodisperse catalysts or quantum points.

Penning discharge ion source with self-cleaning aperture

DOEpatents

Gavin, Basil F.; MacGill, Robert A.; Thatcher, Raymond K.

1982-01-01

An ion source of the Penning discharge type having a self-cleaning aperture is provided by a second dynode (24) with an exit aperture (12) in a position opposite a first dynode 10a, from which the ions are sputtered, two opposing cathodes (14, 16), each with an anode (18, 20) for accelerating electrons emitted from the cathodes into a cylindrical space defined by the first and second dynode. A support gas maintained in this space is ionized by the electrons. While the cathodes are supplied with a negative pulse to emit electrons, the first dynode is supplied with a negative pulse (e.g., -300 V) to attract atoms of the ionized gas (plasma). At the same time, the second dynode may also be supplied with a small voltage that is negative with respect to the plasma (e.g., -5 V) for tuning the position of the plasma miniscus for optimum extraction geometry. When the negative pulse to the first dynode is terminated, the second dynode is driven strongly negative (e.g., -600 V) thereby allowing heavy sputtering to take place for a short period to remove virtually all of the atoms deposited on the second dynode from material sputtered off the first dynode. An extractor (22) immediately outside the exit aperture of the second dynode is maintained at ground potential during this entire period of sputtering while the anode, dynode and cathode reference voltage is driven strongly positive (about +20 kV to +30 kV) so that ions accelerated through the aperture will be at ground potential. In that manner, material from the first dynode deposited on the second dynode will be sputtered, in time, to add to the ion beam. Atoms sputtered from the second dynode which do not become ionized and exit through the slit will be redeposited on the first dynode, and hence recycled for further ion beam generation during subsequent operating cycles.

Solar Ion Sputter Deposition in the Lunar Regolith: Experimental Simulation Using Focused-Ion Beam Techniques

NASA Technical Reports Server (NTRS)

Christoffersen, R.; Rahman, Z.; Keller, L. P.

2012-01-01

As regions of the lunar regolith undergo space weathering, their component grains develop compositionally and microstructurally complex outer coatings or "rims" ranging in thickness from a few 10 s to a few 100's of nm. Rims on grains in the finest size fractions (e.g., <20 m) of mature lunar regoliths contain optically-active concentrations of nm size metallic Fe spherules, or "nanophase Fe(sup o)" that redden and attenuate optical reflectance spectral features important in lunar remote sensing. Understanding the mechanisms for rim formation is therefore a key part of connecting the drivers of mineralogical and chemical changes in the lunar regolith with how lunar terrains are observed to become space weathered from a remotely-sensed point of view. As interpreted based on analytical transmission electron microscope (TEM) studies, rims are produced from varying relative contributions from: 1) direct solar ion irradiation effects that amorphize or otherwise modify the outer surface of the original host grain, and 2) nanoscale, layer-like, deposition of extrinsic material processed from the surrounding soil. This extrinsic/deposited material is the dominant physical host for nanophase Fe(sup o) in the rims. An important lingering uncertainty is whether this deposited material condensed from regolith components locally vaporized in micrometeorite or larger impacts, or whether it formed as solar wind ions sputtered exposed soil and re-deposited the sputtered ions on less exposed areas. Deciding which of these mechanisms is dominant, or possibility exclusive, has been hampered because there is an insufficient library of chemical and microstructural "fingerprints" to distinguish deposits produced by the two processes. Experimental sputter deposition / characterization studies relevant to rim formation have particularly lagged since the early post-Apollo experiments of Hapke and others, especially with regard to application of TEM-based characterization techniques. Here we report on a novel design for simulating solar ion sputter deposition in the lunar regolith, with characterization of the resulting sputter deposits by an array of advanced analytical TEM techniques.

Energy spectrum of argon ions emitted from Filippov type Sahand plasma focus.

PubMed

Mohammadnejad, M; Pestehe, S J; Mohammadi, M A

2013-07-01

The energy and flux of the argon ions produced in Sahand plasma focus have been measured by employing a well-designed Faraday cup. The secondary electron emission effects on the ion signals are simulated and the dimensions of Faraday cup are optimized to minimize these effects. The measured ion energy spectrum is corrected for the ion energy loss and charge exchange in the background gas. The effects of the capacitor bank voltage and working gas pressure on the ion energy spectrum are also investigated. It has been shown that the emitted ion number per energy increases as the capacitor bank voltage increases. Decreasing the working gas pressure leads to the increase in the number of emitted ion per energy.

Effect of BST film thickness on the performance of tunable interdigital capacitors grown by MBE

NASA Astrophysics Data System (ADS)

Meyers, Cedric J. G.; Freeze, Christopher R.; Stemmer, Susanne; York, Robert A.

2017-12-01

Voltage-tunable, interdigital capacitors (IDCs) were fabricated on Ba0.29Sr0.71TiO3 grown by hybrid molecular beam epitaxy (MBE). In this growth technique, we utilize the metal-organic precursor titanium tetraisopropoxide rather than solid-source Ti as with conventional MBE. Two samples of varying BaxSr(1-x)TiO3 (BST) thicknesses were fabricated and analyzed. High-quality, epitaxial Pt electrodes were deposited by sputtering from a high-purity Pt target at 825 °C. The Pt electrodes were patterned and etched by argon ion milling, passivated with reactively sputtered SiO2, and then metallized with lift-off Ti/Au. The fabricated devices consisted of two-port IDCs embedded in ground-signal-ground, coplanar waveguide (CPW) transmission lines to enable radio-frequency (RF) probing. The sample included open and thru de-embedding structures to remove pad and CPW parasitic impedances. Two-port RF scattering (S) parameters were measured from 100 MHz to 40 GHz while DC bias was stepped from 0 V to 100 V. The IDCs exhibit a high zero-bias radio-frequency (RF) quality factor (Q) approaching 200 at 1 GHz and better than 2.3:1 capacitance tuning for the 300-nm-thick sample. Differences in the Q(V) and C(V) response with varying thicknesses indicate that unknown higher order material phenomena are contributing to the loss and tuning characteristics of the material.

Influence of argon and oxygen on charge-state-resolved ion energydistributions of filtered aluminum arcs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosen, Johanna; Anders, Andre; Mraz, Stanislav

2006-03-23

The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range 0.5 8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow charge-state distribution as wellmore » as a narrow IED. These data may enable tailoring thin-film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.« less

Surface wet-ability modification of thin PECVD silicon nitride layers by 40 keV argon ion treatments

NASA Astrophysics Data System (ADS)

Caridi, F.; Picciotto, A.; Vanzetti, L.; Iacob, E.; Scolaro, C.

2015-10-01

Measurements of wet-ability of liquid drops have been performed on a 30 nm silicon nitride (Si3N4) film deposited by a PECVD reactor on a silicon wafer and implanted by 40 keV argon ions at different doses. Surface treatments by using Ar ion beams have been employed to modify the wet-ability. The chemical composition of the first Si3N4 monolayer was investigated by means of X-ray Photoelectron Spectroscopy (XPS). The surface morphology was tested by Atomic Force Microscopy (AFM). Results put in evidence the best implantation conditions for silicon nitride to increase or to reduce the wet-ability of the biological liquid. This permits to improve the biocompatibility and functionality of Si3N4. In particular experimental results show that argon ion bombardment increases the contact angle, enhances the oxygen content and increases the surface roughness.

Developing a scalable inert gas ion thruster

NASA Technical Reports Server (NTRS)

James, E.; Ramsey, W.; Steiner, G.

1982-01-01

Analytical studies to identify and then design a high performance scalable ion thruster operating with either argon or xenon for use in large space systems are presented. The magnetoelectrostatic containment concept is selected for its efficient ion generation capabilities. The iterative nature of the bounding magnetic fields allows the designer to scale both the diameter and length, so that the thruster can be adapted to spacecraft growth over time. Three different thruster assemblies (conical, hexagonal and hemispherical) are evaluated for a 12 cm diameter thruster and performance mapping of the various thruster configurations shows that conical discharge chambers produce the most efficient discharge operation, achieving argon efficiencies of 50-80% mass utilization at 240-310 eV/ion and xenon efficiencies of 60-97% at 240-280 eV/ion. Preliminary testing of the large 30 cm thruster, using argon propellant, indicates a 35% improvement over the 12 cm thruster in mass utilization efficiency. Since initial performance is found to be better than projected, a larger 50 cm thruster is already in the development stage.

Kinetic and Potential Sputtering of Lunar Regolith: The Contribution of the Heavy Highly Charged (Minority) Solar Wind Ions

NASA Technical Reports Server (NTRS)

Meyer, F. W.; Barghouty, A. F.

2012-01-01

Solar wind sputtering of the lunar surface helps determine the composition of the lunar exosphere and contributes to surface weathering. To date, only the effects of the two dominant solar wind constituents, H+ and He+, have been considered. The heavier, less abundant solar wind constituents have much larger sputtering yields because they have greater mass (kinetic sputtering) and they are highly charged (potential sputtering) Their contribution to total sputtering can therefore be orders of magnitude larger than their relative abundances would suggest

Controlling the surface termination of NdGaO3 (110): the role of the gas atmosphere.

PubMed

Cavallaro, Andrea; Harrington, George F; Skinner, Stephen J; Kilner, John A

2014-07-07

In this work the effect of gas atmosphere on the surface termination reconstruction of single crystal NdGaO3 (110) (NGO) during thermal annealing was analyzed. Using Low Energy Ion Scattering (LEIS) it has been possible to study the chemical composition of the first atomic layer of treated NGO single crystal samples. NGO has been analyzed both as-received and after a specific thermal treatment at 1000 °C under different gas fluxes (argon, nitrogen, static air, synthetic air, nitrogen plus 5% hydrogen and wet synthetic air respectively). Thermal annealing of perovskite single crystals, as already reported in the literature, is used to obtain a fully A-cation surface termination. Nevertheless the effect of the gas-atmosphere on this process has not been previously reported. By the use of sequential low energy Ar(+) sputtering combined with the primary ion LEIS analysis, the reconstruction of the outermost atomic layers has allowed the clarification of the mechanism of NGO neodymium surface enrichment. It is proposed that the gallium at the surface is submitted to a reduction/evaporation mechanism caused by low oxygen partial pressure and/or high water pressure in the vector gas. Below the first surface atomic layers of an as-received NGO single-crystal a gallium-rich phase has also been observed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Robaee, M.S.; Krishna, M.G.; Rao, K.N.

Single layer films of CeO{sub 2} have been deposited both by conventional electron beam evaporation and ion assisted deposition with oxygen and argon ions. A broad beam Kaufman ion source (3 cm diam) has been used to generate the ions. A systematic study has been made on optical properties such as refractive index, extinction coefficient and inhomogeneity of the films as a function of: (1) oxygen partial pressure in the range 1{times}10{sup {minus}4} to 1{times}10{sup {minus}5} mbar. (2) Incidence of oxygen ions with energy in the range 300--700 eV and current density in the range 50--220 {mu}A/cm{sup 2}. (3) Incidencemore » of mixed argon and oxygen ions of different ratios. The refractive index of the films deposited under the influence of ion bombardment showed higher indices than the conventionally evaporated films. The maximum index obtained with an oxygen ion bombardment was 2.3 at an ion energy of 600 eV and current density of 220 {mu}A/cm{sup 2}. The bombardment of the films with a mixed argon--oxygen (25% Ar) ion beam of the same energy and current density was found to further increase the refractive index. The extinction coefficient in both cases was negligible.« less

MEMS floating element sensor array for wall shear stress measurement under a turbulent boundary layer

NASA Astrophysics Data System (ADS)

Zong, Zhaowang

A novel electrochromic thin film transistor (EC-TFT) was fabricated and characterized in this work. This concept relies on ion transport to control gating. The channel material is tungsten oxide (WOx), produced by reactive magnetron sputtering. In its oxidized state WO3 is a transparent, wide band gap insulator (> 3 eV). However upon intercalation of light ions (H+, Li+) the material becomes both electrically conducting and opaque to visible light. This allows the EC-TFT to generate a complementary optical response. We optimized the fabrication of individual layers of the EC-TFT, and found that controlling the stoichiometry of WOx is a key step. Using RF magnetron sputtering, it was found that there is a narrow window to obtain material capable of reversible switching. Fully oxidized films proved it is difficult to intercalate ions efficiently. In contrast, insufficient oxygen produced films that were always in a metallic like state. Best results were obtained with the sputter power set at 200 W using O2 fractions of 42%-46% in argon. In the preliminary studies, the device was tested in a two-step fashion. First, devices were placed in solution and cyclic voltammetry was used to set the level of ion intercalation. Samples were then removed from the electrolyte, dried, and the source/drain current was measured on a probe station. This demonstrated the concept of the EC-TFT, showing that the transistor could be turned on and off reversely with a current ratio of Ion/Ioff ~ 1000, and showed significant color change during the intercalation. However, the conductivity in off state was too high to be a promising transistor, the two step approach made the data rather noisy, it was difficult to make good contacts and this was not an in situ measurement. In order to get the in situ measurement, macrodevices with large electrodes were fabricated and characterized, which made it easier to make electrical contacts. However, after the initial cycle the macrodevices were always in on state and could not be turned off because of the dielectric. In addition, it showed no significant color change. The top source/drain structure showed similar behavior as the bottom configuration. It was found that in these configurations the supply of electrons was insufficient to allow intercalation, and permanent defects in the Al2O3 dielectric developed to compensate. To address these issues, 3-terminal devices were fabricated and characterized simultaneously. These devices showed similar behaviors with the preliminary 2-step device. The IDS increased with decreasing gate biasing with a low threshold voltage -0.8 V. In addition, we observed the color changing. However, the conduction through the electrolyte resulted very low on/off ratio (<5). In conclusion, it is the conduction through the electrolyte contributes to the low on/off ratio.

Tuning the resistive switching properties of TiO2-x films

NASA Astrophysics Data System (ADS)

Ghenzi, N.; Rozenberg, M. J.; Llopis, R.; Levy, P.; Hueso, L. E.; Stoliar, P.

2015-03-01

We study the electrical characteristics of TiO2-x-based resistive switching devices fabricated with different oxygen/argon flow ratio during the oxide thin film sputtering deposition. Upon minute changes in this fabrication parameter, three qualitatively different device characteristics were accessed in the same system, namely, standard bipolar resistive switching, electroforming-free devices, and devices with multi-step breakdown. We propose that small variations in the oxygen/ argon flow ratio result in relevant changes of the oxygen vacancy concentration, which is the key parameter determining the resistive switching behavior. The coexistence of percolative or non-percolative conductive filaments is also discussed. Finally, the hypothesis is verified by means of the temperature dependence of the devices in low resistance state.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattox, D.M.; Sharp, D.J.

A Veeco microetch system which uses a Kaufman type ion source has been used to study ion erosion yields for a variety of materials of possible interest in CTR wall coating applications. A schematic diagram of the Kaufman gun and etching chamber are given. The ion beam is nearly monoenergetic (within several eV). The extracted ion beam consists of a mixture of H/sub 2//sup +/ and H/sup +/. A H/sub 2//sup +/ ion will have a sputtering yield equivalent to 2H/sup +/ ions with one-half the energy of the H/sub 2//sup +/ ion. For most of these investigations, the chargemore » compensation filament is removed to avoid sputtering of the tungsten filament.« less

Nanopatterning of swinging substrates by ion-beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Sun Mi; Kim, J.-S., E-mail: jskim@sm.ac.kr

Graphite substrates are azimuthally swung during ion-beam sputtering (IBS) at a polar angle θ = 78° from the surface normal. The swinging of the substrate not only causes quasi-two-dimensional mass transport but also makes various sputter effects from the different incident angles to work together. Through variation of the swing angle, both the transport and sputtering effects synergistically produce a series of salient patterns, such as asymmetric wall-like structures, which can grow to several tens of nanometers and exhibit a re-entrant orientational change with the increased swing angle. Thus, the present work demonstrates that dynamic variables such as the swing angle, whichmore » have been little utilized, offer an additional parameter space that can be exploited to diversify the sputtered patterns, thereby expanding the applicability of an IBS as well as the comprehension of the IBS nano patterning mechanism.« less

Ion beam sputter target and method of manufacture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higdon, Clifton; Elmoursi, Alaa A.; Goldsmith, Jason

A target for use in an ion beam sputtering apparatus made of at least two target tiles where at least two of the target tiles are made of different chemical compositions and are mounted on a main tile and geometrically arranged on the main tile to yield a desired chemical composition on a sputtered substrate. In an alternate embodiment, the tiles are of varied thickness according to the desired chemical properties of the sputtered film. In yet another alternate embodiment, the target is comprised of plugs pressed in a green state which are disposed in cavities formed in a mainmore » tile also formed in a green state and the assembly can then be compacted and then sintered.« less

Germanium detector passivated with hydrogenated amorphous germanium

DOEpatents

Hansen, William L.; Haller, Eugene E.

1986-01-01

Passivation of predominantly crystalline semiconductor devices (12) is provided for by a surface coating (21) of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating (21) of amorphous germanium onto the etched and quenched diode surface (11) in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices (12), which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating (21) compensates for pre-existing undesirable surface states as well as protecting the semiconductor device (12) against future impregnation with impurities.

Investigation of plasma dynamics during the growth of amorphous titanium dioxide thin films

NASA Astrophysics Data System (ADS)

Kim, Jin-Soo; Jee, Hyeok; Yu, Young-Hun; Seo, Hye-Won

2018-06-01

We have grown amorphous titanium dioxide thin films by reactive DC sputtering method using a different argon/oxygen partial pressure at a room temperature. The plasma dynamics of the process, reactive and sputtered gas particles was investigated via optical emission spectroscopy. We then studied the correlations between the plasma states and the structural/optical properties of the films. The growth rate and morphology of the titanium dioxide thin films turned out to be contingent with the population and the energy profile of Ar, O, and TiO plasma. In particular, the films grown under energetic TiO plasma have shown a direct band-to-band transition with an optical energy band gap up to ∼4.2 eV.

Semiconductor with protective surface coating and method of manufacture thereof. [Patent application

DOEpatents

Hansen, W.L.; Haller, E.E.

1980-09-19

Passivation of predominantly crystalline semiconductor devices is provided for by a surface coating of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating of amorphous germanium onto the etched and quenched diode surface in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices, which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating compensates for pre-existing undesirable surface states as well as protecting the semiconductor device against future impregnation with impurities.

The Lamont--Doherty Geological Observatory Isolab 54 isotope ratio mass spectrometer

NASA Astrophysics Data System (ADS)

England, J. G.; Zindler, A.; Reisberg, L. C.; Rubenstone, J. L.; Salters, V.; Marcantonio, F.; Bourdon, B.; Brueckner, H.; Turner, P. J.; Weaver, S.; Read, P.

1992-12-01

The Lamont--Doherty Geological Observatory (LDGO) Isolab 54 is a double focussing isotope ratio mass spectrometer that allows the measurement of thermal ions produced on a hot filament, (thermal-ionization mass spectrometry (TIMS)), secondary ions produced by sputtering a sample using a primary ion beam, (secondary ion mass spectrometry (SIMS)), and sputtered neutrals resonantly ionized using laser radiation, (sputter-induced resonance ionization mass spectrometry (SIRIMS)). Sputtering is carried out using an Ar primary beam generated in a duoplasmatron and focussed onto the sample using a two-lens column. Resonance ionization is accomplished using a frequency-doubled dye laser pumped by an excimer laser. The Isolab's forward geometry analyzer, consisting of an electrostatic followed by a magnetic sector, allows the simultaneous collection of different isotopes of the same element. This instrument is the first to have a multicollector that contains an ion-counting system based on a microchannel plate as well as traditional Faraday cups. A second electrostatic sector after the multicollector is equipped with an ion-counting Daly detector to allow high abundance sensitivity for measurements of large dynamics range. Selectable source, collector, [alpha] and energy slits on the instrument allow analyses to be made over a range of mass resolving powers and analyzer acceptances. Recent applications of the instrument have included the analyses of U by TIMS, Hf, Th and Re by SIMS and Re and Os by SIRIMS.

Conformal growth of Mo/Si multilayers on grating substrates using collimated ion beam sputtering

NASA Astrophysics Data System (ADS)

Voronov, D. L.; Gawlitza, P.; Cambie, R.; Dhuey, S.; Gullikson, E. M.; Warwick, T.; Braun, S.; Yashchuk, V. V.; Padmore, H. A.

2012-05-01

Deposition of multilayers on saw-tooth substrates is a key step in the fabrication of multilayer blazed gratings (MBG) for extreme ultraviolet and soft x-rays. Growth of the multilayers can be perturbed by shadowing effects caused by the highly corrugated surface of the substrates, which results in distortion of the multilayer stack structure and degradation of performance of MBGs. To minimize the shadowing effects, we used an ion-beam sputtering machine with a highly collimated atomic flux to deposit Mo/Si multilayers on saw-tooth substrates. The sputtering conditions were optimized by finding a balance between smoothening and roughening processes in order to minimize degradation of the groove profile in the course of deposition and at the same time to keep the interfaces of a multilayer stack smooth enough for high efficiency. An optimal value of energy of 200 eV for sputtering Kr+ ions was found by deposition of test multilayers on flat substrates at a range of ion energies. Two saw-tooth substrates were deposited at energies of 200 eV and 700 eV for the sputtering ions. It was found that reduction of the ion energy improved the blazing performance of the MBG and resulted in a 40% gain in the diffraction efficiency due to better replication of the groove profile by the multilayer. As a result of the optimization performed, an absolute diffraction efficiency of 28.8% was achieved for the 2nd blaze order of the MBG with a groove density of 7350 lines/mm at a wavelength of 13.5 nm. Details of the growth behavior of the multilayers on flat and saw-tooth substrates are discussed in terms of the linear continuous model of film growth.

Conformal growth of Mo/Si multilayers on grating substrates using collimated ion beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voronov, D. L.; Cambie, R.; Dhuey, S.

2012-05-01

Deposition of multilayers on saw-tooth substrates is a key step in the fabrication of multilayer blazed gratings (MBG) for extreme ultraviolet and soft x-rays. Growth of the multilayers can be perturbed by shadowing effects caused by the highly corrugated surface of the substrates, which results in distortion of the multilayer stack structure and degradation of performance of MBGs. To minimize the shadowing effects, we used an ion-beam sputtering machine with a highly collimated atomic flux to deposit Mo/Si multilayers on saw-tooth substrates. The sputtering conditions were optimized by finding a balance between smoothening and roughening processes in order to minimizemore » degradation of the groove profile in the course of deposition and at the same time to keep the interfaces of a multilayer stack smooth enough for high efficiency. An optimal value of energy of 200 eV for sputtering Kr{sup +} ions was found by deposition of test multilayers on flat substrates at a range of ion energies. Two saw-tooth substrates were deposited at energies of 200 eV and 700 eV for the sputtering ions. It was found that reduction of the ion energy improved the blazing performance of the MBG and resulted in a 40% gain in the diffraction efficiency due to better replication of the groove profile by the multilayer. As a result of the optimization performed, an absolute diffraction efficiency of 28.8% was achieved for the 2nd blaze order of the MBG with a groove density of 7350 lines/mm at a wavelength of 13.5 nm. Details of the growth behavior of the multilayers on flat and saw-tooth substrates are discussed in terms of the linear continuous model of film growth.« less

Development of advanced inert-gas ion thrusters

NASA Technical Reports Server (NTRS)

Poeschel, R. L.

1983-01-01

Inert gas ion thruster technology offers the greatest potential for providing high specific impulse, low thrust, electric propulsion on large, Earth orbital spacecraft. The development of a thruster module that can be operated on xenon or argon propellant to produce 0.2 N of thrust at a specific impulse of 3000 sec with xenon propellant and at 6000 sec with argon propellant is described. The 30 cm diameter, laboratory model thruster is considered to be scalable to produce 0.5 N thrust. A high efficiency ring cusp discharge chamber was used to achieve an overall thruster efficiency of 77% with xenon propellant and 66% with argon propellant. Measurements were performed to identify ion production and loss processes and to define critical design criteria (at least on a preliminary basis).

Thin film characterization by laser interferometry combined with SIMS

NASA Astrophysics Data System (ADS)

Kempf, J.; Nonnenmacher, M.; Wagner, H. H.

1988-10-01

Thin film properties of technologically important materials (Si, GaAs, SiO2, WSix) have been measured by using a novel technique that combines secondary ion mass spectrometry (SIMS) and laser interferometry. The simultaneous measurement of optical phase and reflectance as well as SIMS species during ion sputtering yielded optical constants, sputtering rates and composition of thin films with high depth resolution. A model based on the principle of multiple reflection within a multilayer structure, which considered also transformation of the film composition in depth and time during sputtering, was fitted to the reflectance and phase data. This model was applied to reveal the transformation of silicon by sputtering with O{2/+} ions. Special attention was paid to the preequilibrium phase of the sputter process (amorphization, oxidation, and volume expansion). To demonstrate the analytical potential of our method the multilayer system WSix/poly-Si/SiO2/Si was investigated. The physical parameters and the stoichiometry of tungsten suicide were determined for annealed as well as deposited films. A highly sensitive technique that makes use of a Fabry-Perot etalon integrated with a Michelson type interferometer is proposed. This two-stage interferometer has the potential to profile a sample surface with subangstroem resolution.

Low Energy Sputtering Experiments for Ion Engine Lifetime Assessment

NASA Technical Reports Server (NTRS)

Duchemin Olivier B.; Polk, James E.

1999-01-01

The sputtering yield of molybdenum under xenon ion bombardment was measured using a Quartz Crystal Microbalance. The measurements were made for ion kinetic energies in the range 100-1keV on molybdenum films deposited by magnetron sputtering in conditions optimized to reproduce or approach bulk-like properties. SEM micrographs for different anode bias voltages during the deposition are compared, and four different methods were implemented to estimate the density of the molybdenum films. A careful discussion of the Quartz Crystal Microbalance is proposed and it is shown that this method can be used to measure mass changes that are distributed unevenly on the crystal electrode surface, if an analytical expression is known for the differential mass-sensitivity of the crystal and the erosion profile. Finally, results are presented that are in good agreement with previously published data, and it is concluded that this method holds the promise of enabling sputtering yield measurements at energies closer to the threshold energy in the very short term.

Cu self-sputtering MD simulations for 0.1-5 keV ions at elevated temperatures

NASA Astrophysics Data System (ADS)

Metspalu, Tarvo; Jansson, Ville; Zadin, Vahur; Avchaciov, Konstantin; Nordlund, Kai; Aabloo, Alvo; Djurabekova, Flyura

2018-01-01

Self-sputtering of copper under high electric fields is considered to contribute to plasma buildup during a vacuum breakdown event frequently observed near metal surfaces, even in ultra high vacuum condition in different electric devices. In this study, by means of molecular dynamics simulations, we analyze the effect of surface temperature and morphology on the yield of self-sputtering of copper with ion energies of 0.1-5 keV. We analyze all three low-index surfaces of Cu, {1 0 0}, {1 1 0} and {1 1 1}, held at different temperatures, 300 K, 500 K and 1200 K. The surface roughness relief is studied by either varying the angle of incidence on flat surfaces, or by using arbitrary roughened surfaces, which result in a more natural distribution of surface relief variations. Our simulations provide detailed characterization of copper self-sputtering with respect to different material temperatures, crystallographic orientations, surface roughness, energies, and angles of ion incidence.

Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hänninen, Tuomas, E-mail: tuoha@ifm.liu.se; Schmidt, Susann; Jensen, Jens

2015-09-15

Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content.more » The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.« less

Monte Carlo simulations of secondary electron emission due to ion beam milling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahady, Kyle; Tan, Shida; Greenzweig, Yuval

We present a Monte Carlo simulation study of secondary electron emission resulting from focused ion beam milling of a copper target. The basis of this study is a simulation code which simulates ion induced excitation and emission of secondary electrons, in addition to simulating focused ion beam sputtering and milling. This combination of features permits the simulation of the interaction between secondary electron emission, and the evolving target geometry as the ion beam sputters material. Previous ion induced SE Monte Carlo simulation methods have been restricted to predefined target geometries, while the dynamic target in the presented simulations makes thismore » study relevant to image formation in ion microscopy, and chemically assisted ion beam etching, where the relationship between sputtering, and its effects on secondary electron emission, is important. We focus on a copper target, and validate our simulation against experimental data for a range of: noble gas ions, ion energies, ion/substrate angles and the energy distribution of the secondary electrons. We then provide a detailed account of the emission of secondary electrons resulting from ion beam milling; we quantify both the evolution of the yield as high aspect ratio valleys are milled, as well as the emission of electrons within these valleys that do not escape the target, but which are important to the secondary electron contribution to chemically assisted ion induced etching.« less

Electronic sputtering of LiF, CaF2, LaF3 and UF4 with 197 MeV Au ions. Is the stoichiometry of atom emission preserved?

NASA Astrophysics Data System (ADS)

Toulemonde, M.; Assmann, W.; Muller, D.; Trautmann, C.

2017-09-01

Sputtering experiments with swift heavy ions in the electronic energy loss regime were performed by using the catcher technique in combination with elastic recoil detection analysis. Four different fluoride targets, LiF, CaF2, LaF3 and UF4 were irradiated in the electronic energy loss regime using 197 MeV Au ions. The angular distribution of particles sputtered from the surface of freshly cleaved LiF and CaF2 single crystals is composed of a broad cosine distribution superimposed by a jet-like peak that appears perpendicular to the surface independent of the angle of beam incidence. For LiF, the particle emission in the entire angular distribution (jet plus broad cosine component) is stoichiometric, whereas for CaF2 the ratio of the sputtered F to Ca particles is at large angles by a factor of two smaller than the stoichiometry of the crystal. For single crystalline LaF3 no jet component is observed and the angular distribution is non-stoichiometric with the number of sputtered F particles being slightly larger than the number of sputtered La particles. In the case of UF4, the target was polycrystalline and had a much rougher surface compared to cleaved crystals. This destroys the appearance of a possible jet component leading to a broad angular distribution. The ratio of sputtered U atoms compared to F atoms is in the order of 1-2, i.e. the number of collected particles on the catcher is also non-stoichiometric. Such unlike behavior of particles sputtered from different fluoride crystals creates new questions.

Hybrid solar cells based on dc magnetron sputtered films of n-ITO on APMOVPE grown p-InP

NASA Technical Reports Server (NTRS)

Coutts, T. J.; Li, X.; Wanlass, M. W.; Emery, K. A.; Gessert, T. A.

1988-01-01

Hybrid indium-tin-oxide (ITO)/InP solar cells are discussed. The cells are constructed by dc magnetron sputter deposition of ITO onto high-quality InP films grown by atmospheric pressure metal-organic vapor-phase epitaxy (APMOVPE). A record efficiency of 18.9 percent, measured under standard Solar Energy Research Institute reporting conditions, has been obtained. The p-InP surface is shown to be type converted, principally by the ITO, but with the extent of conversion being modified by the nature of the sputtering gas. The deposition process, in itself, is not responsible for the type conversion. Dark currents have been suppressed by more than three orders of magnitude by the addition of hydrogen to the sputtering gas during deposition of a thin (5 nm) interface layer. Without this layer, and using only the more usual argon/oxygen mixture, the devices had poorer efficiencies and were unstable. A discussion of associated quantum efficiencies and capacitance/voltage measurements is also presented from which it is concluded that further improvements in efficiency will result from better control over the type-conversion process.

Measuring Compositions in Organic Depth Profiling: Results from a VAMAS Interlaboratory Study.

PubMed

Shard, Alexander G; Havelund, Rasmus; Spencer, Steve J; Gilmore, Ian S; Alexander, Morgan R; Angerer, Tina B; Aoyagi, Satoka; Barnes, Jean-Paul; Benayad, Anass; Bernasik, Andrzej; Ceccone, Giacomo; Counsell, Jonathan D P; Deeks, Christopher; Fletcher, John S; Graham, Daniel J; Heuser, Christian; Lee, Tae Geol; Marie, Camille; Marzec, Mateusz M; Mishra, Gautam; Rading, Derk; Renault, Olivier; Scurr, David J; Shon, Hyun Kyong; Spampinato, Valentina; Tian, Hua; Wang, Fuyi; Winograd, Nicholas; Wu, Kui; Wucher, Andreas; Zhou, Yufan; Zhu, Zihua; Cristaudo, Vanina; Poleunis, Claude

2015-08-20

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interlaboratory study on the measurement of composition in organic depth profiling. Layered samples with known binary compositions of Irganox 1010 and either Irganox 1098 or Fmoc-pentafluoro-l-phenylalanine in each layer were manufactured in a single batch and distributed to more than 20 participating laboratories. The samples were analyzed using argon cluster ion sputtering and either X-ray photoelectron spectroscopy (XPS) or time-of-flight secondary ion mass spectrometry (ToF-SIMS) to generate depth profiles. Participants were asked to estimate the volume fractions in two of the layers and were provided with the compositions of all other layers. Participants using XPS provided volume fractions within 0.03 of the nominal values. Participants using ToF-SIMS either made no attempt, or used various methods that gave results ranging in error from 0.02 to over 0.10 in volume fraction, the latter representing a 50% relative error for a nominal volume fraction of 0.2. Error was predominantly caused by inadequacy in the ability to compensate for primary ion intensity variations and the matrix effect in SIMS. Matrix effects in these materials appear to be more pronounced as the number of atoms in both the primary analytical ion and the secondary ion increase. Using the participants' data we show that organic SIMS matrix effects can be measured and are remarkably consistent between instruments. We provide recommendations for identifying and compensating for matrix effects. Finally, we demonstrate, using a simple normalization method, that virtually all ToF-SIMS participants could have obtained estimates of volume fraction that were at least as accurate and consistent as XPS.

Measuring Compositions in Organic Depth Profiling: Results from a VAMAS Interlaboratory Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shard, A. G.; Havelund, Rasmus; Spencer, Steve J.

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interlaboratory study on the measurement of composition in organic depth profiling. Layered samples with known binary compositions of Irganox 1010 and either Irganox 1098 or Fmoc-pentafluoro-L-phenylalanine in each layer were manufactured in a single batch and distributed to more than 20 participating laboratories. The samples were analyzed using argon cluster ion sputtering and either X-ray Photoelectron Spectroscopy (XPS) or Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) to generate depth profiles. Participants were asked to estimate the volume fractions in two of the layers and were provided withmore » the compositions of all other layers. Participants using XPS provided volume fractions within 0.03 of the nominal values. Participants using ToF-SIMS either made no attempt, or used various methods that gave results ranging in error from 0.02 to over 0.10 in volume fraction, the latter representing a 50% relative error for a nominal volume fraction of 0.2. Error was predominantly caused by inadequacy in the ability to compensate for primary ion intensity variations and the matrix effect in SIMS. Matrix effects in these materials appear to be more pronounced as the number of atoms in both the primary analytical ion and the secondary ion increase. Using the participants’ data we show that organic SIMS matrix effects can be measured and are remarkably consistent between instruments. We provide recommendations for identifying and compensating for matrix effects. Finally we demonstrate, using a simple normalization method, that virtually all ToF-SIMS participants could have obtained estimates of volume fraction that were at least as accurate and consistent as XPS.« less

Rapid evaluation of ion thruster lifetime using optical emission spectroscopy

NASA Technical Reports Server (NTRS)

Rock, B. A.; Mantenieks, M. A.; Parsons, M. L.

1985-01-01

A major life-limiting phenomenon of electric thrusters is the sputter erosion of discharge chamber components. Thrusters for space propulsion are required to operate for extended periods of time, usually in excess of 10,000 hr. Lengthy and very costly life-tests in high-vacuum facilities have been required in the past to determine the erosion rates of thruster components. Alternative methods for determining erosion rates which can be performed in relatively short periods of time at considerably lower costs are studied. An attempt to relate optical emission intensity from an ion bombarded surface (screen grid) to the sputtering rate of that surface is made. The model used a kinetic steady-state (KSS) approach, balancing the rates of population and depopulation of ten low-lying excited states of the sputtered molybdenum atom (MoI) with those of the ground state to relate the spectral intensities of the various transitions of the MoI to the population densities. Once this is accomplished, the population density can be related to the sputtering rate of the target. Radiative and collisional modes of excitation and decay are considered. Since actual data has not been published for MoI excitation rate and decay constants, semiempirical equations are used. The calculated sputtering rate and intensity is compared to the measured intensity and sputtering rates of the 8 and 30 cm ion thrusters.

Self-organization and self-limitation in high power impulse magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anders, Andre

The plasma over the racetrack in high power impulse magnetron sputtering develops in traveling ionization zones. Power densities can locally reach 10{sup 9} W/m{sup 2}, which is much higher than usually reported. Ionization zones move because ions are 'evacuated' by the electric field, exposing neutrals to magnetically confined, drifting electrons. Drifting secondary electrons amplify ionization of the same ionization zone where the primary ions came from, while sputtered and outgassing atoms are supplied to the following zone(s). Strong density gradients parallel to the target disrupt electron confinement: a negative feedback mechanism that stabilizes ionization runaway.

Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces

NASA Astrophysics Data System (ADS)

Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; de los Arcos, Teresa; Benedikt, Jan; von Keudell, Achim

2013-10-01

A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP).

A 9700-hour durability test of a five centimeter diameter ion thruster

NASA Technical Reports Server (NTRS)

Nakanishi, S.; Finke, R. C.

1973-01-01

A modified Hughes SIT-5 thruster was life-tested at the Lewis Research Center. The final 2700 hours of the test are described with a charted history of thruster operating parameters and off-normal events. Performance and operating characteristics were nearly constant throughout the test except for neutralizer heater power requirements and accelerator drain current. A post-shutdown inspection revealed sputter erosion of ion chamber components and component flaking of sputtered metal. Several flakes caused beamlet divergence and anomalous grid erosion, causing the test to be terminated. All sputter erosion sources were identified.

Scanning-electron-microscopy observations and mechanical characteristics of ion-beam-sputtered surgical implant alloys

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Meyer, M. L.; Ling, J. S.

1977-01-01

An electron bombardment ion thruster was used as an ion source to sputter the surfaces of orthopedic prosthetic metals. Scanning electron microscopy photomicrographs were made of each ion beam textured surface. The effect of ion texturing an implant surface on its bond to bone cement was investigated. A Co-Cr-W alloy and surgical stainless steel were used as representative hard tissue implant materials to determine effects of ion texturing on bulk mechanical properties. Work was done to determine the effect of substrate temperature on the development of an ion textured surface microstructure. Results indicate that the ultimate strength of the bulk materials is unchanged by ion texturing and that the microstructure will develop more rapidly if the substrate is heated prior to ion texturing.

Hydrophobization of track membrane surface by ion-plasma sputtering method

NASA Astrophysics Data System (ADS)

Kuklin, I. E.; Khlebnikov, N. A.; Barashev, N. R.; Serkov, K. V.; Polyakov, E. V.; Zdorovets, M. V.; Borgekov, D. B.; Zhidkov, I. S.; Cholakh, S. O.; Kozlovskiy, A. L.

2017-09-01

This article reviews the possibility of applying inorganic coatings of metal compounds on PTM by ion-plasma sputtering. The main aim of this research is to increase the contact angle of PTM surfaces and to impart the properties of a hydrophobic material to it. After the modification, the initial contact angle increased from 70° to 120°.

An experimental investigation of fractionation by sputter deposition. [application to solar wind irradiation of lunar soil

NASA Technical Reports Server (NTRS)

Paruso, D. M.; Cassidy, W. A.; Hapke, B. W.

1978-01-01

Artificial glass targets composed of elements varying widely in atomic weight were irradiated at an angle of incidence of 45 deg by 2-keV hydrogen ions at a current density of .33 mA/sq cm, and sputtered atoms were caught on a molybdenum film. Analyses of the sputter-deposited films and unsputtered target glasses were carried out by electron microprobe. The backward-sputtered component was found to be enriched in elements of low atomic weight, while the forward-sputtered component was enriched in heavy atoms. These results indicate that at the lunar surface lighter elements and isotopes would tend to be ejected in backward directions, escaping directly through the openings which admit bombarding ions without first striking an adjacent grain surface; heavy elements and isotopes would be forward-sputtered deeper into the soil and be preferentially retained, contributing to the reported enrichments of heavy elements and isotopes. Additional results show that the binding energy of an element in its oxide form influences the sticking coefficient of a sputtered atom; elements of low binding energy are likely to desorb, while elements of high binding energy tend to stick to the first bounce surface.

Techniques for Achieving Zero Stress in Thin Films of Iridium, Chromium, and Nickel

NASA Technical Reports Server (NTRS)

Broadway, David M.; O'Dell, Stephen L.; Ramsey, Brian D.; Weimer, Jeffrey

2015-01-01

We examine techniques for achieving zero intrinsic stress in thin films of iridium, chromium, and nickel deposited by magnetron sputter deposition. The intrinsic stress is further correlated to the microstructural features and physical properties such as surface roughness and optical density at a scale appropriate to soft X-ray wavelengths. The examination of the stress in these materials is motivated by efforts to advance the optical performance of light-weight X-ray space telescopes into the regime of sub-arcsecond resolution through various deposition techniques that rely on control of the film stress to values within 10-100 MPa. A characteristic feature of the intrinsic stress behavior in chromium and nickel is their sensitivity to the magnitude and sign of the intrinsic stress with argon gas pressure and deposition rate, including the existence of a critical argon process pressure that results in zero film stress which scales linearly with the atomic mass of the sputtered species. While the effect of stress reversal with argon pressure has been previously reported by Hoffman and others for nickel and chromium, we report this effect for iridium. In addition to stress reversal, we identify zero stress in the optical functioning iridium layer shortly after island coalescence for low process pressures at a film thickness of approximately 35nm. The measurement of the low values of stress during deposition was achieved with the aid of a sensitive in-situ instrument capable of a minimum detectable level of stress, assuming a 35nm thick film, in the range of 0.40-6.0 MPa for <111> oriented crystalline silicon substrate thicknesses of 70-280 microns, respectively.

Production of bare argon, manganese, iron and nickel nuclei in the Dresden EBIT

NASA Astrophysics Data System (ADS)

Kentsch, U.; Zschornack, G.; Großmann, F.; Ovsyannikov, V. P.; Ullmann, F.; Fritzsche, S.; Surzhykov, A.

2002-02-01

The production of highly charged argon, manganese, iron and nickel ions in a room-temperature electron beam ion trap (EBIT), the Dresden EBIT, has been investigated by means of energy dispersive X-ray spectroscopy of the direct excitation (DE) and radiative recombination (RR) processes. To derive the charge state distributions of the ions in the trap, direct excitation and radiative recombination cross-sections were calculated at electron energies of 8 and 14.4 keV. Based on these theoretical cross-sections and the measured X-ray spectra, the ion densities and the absolute number of ions, which are trapped in the electron beam, are determined for argon, manganese, iron and nickel. Emphasis has been paid to the highly charged ions, including the helium-like and hydrogen-like ions and bare nuclei. In the case of iron we also determined the contributions from lower ionization stages from DE transition lines. It is shown, that in the Dresden EBIT elements at least up to nickel can be fully ionized. Beside energy dispersive spectroscopy it is shown for iron by wavelength dispersive X-ray spectroscopy that with a comparably high gas pressure in the order of 10 -8 mbar carbon-, boron-, beryllium-, lithium- and helium-like iron ions can be produced.

Vacuum Sputtered and Ion-Plated Coatings for Wear and Corrosion Protection

NASA Technical Reports Server (NTRS)

Spalvins, T.

1982-01-01

The plasma or ion-assisted coating techniques such as sputtering and ion plating are discussed in view of wear and corrosion protection. The basic processes and the unique features of the technique are discussed in regard to the synthesis and development of high reliability wear and corrosion resistant films. The ions of the plasma which transfer energy, momentum, and charge to the substrate and the growing films can be beneficially used. As a result, coating adherence and cohesion is improved. Favorable morphological growth such as high density and porosity-free films can be developed, and residual stresses can be reduced.

Laser-induced fluorescence measurements of argon and xenon ion velocities near the sheath boundary in 3 ion species plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yip, Chi-Shung; Hershkowitz, Noah; Severn, Greg

2016-05-15

The Bohm sheath criterion is studied with laser-induced fluorescence in three ion species plasmas using two tunable diode lasers. Krypton is added to a low pressure unmagnetized DC hot filament discharge in a mixture of argon and xenon gas confined by surface multi-dipole magnetic fields. The argon and xenon ion velocity distribution functions are measured at the sheath-presheath boundary near a negatively biased boundary plate. The potential structures of the plasma sheath and presheath are measured by an emissive probe. Results are compared with previous experiments with Ar–Xe plasmas, where the two ion species were observed to reach the sheathmore » edge at nearly the same speed. This speed was the ion sound speed of the system, which is consistent with the generalized Bohm criterion. In such two ion species plasmas, instability enhanced collisional friction was demonstrated [Hershkowitz et al., Phys. Plasmas 18(5), 057102 (2011).] to exist which accounted for the observed results. When three ion species are present, it is demonstrated under most circumstances the ions do not fall out of the plasma at their individual Bohm velocities. It is also shown that under most circumstances the ions do not fall out of the plasma at the system sound speed. These observations are also consistent with the presence of the instabilities.« less

Contributions of solar-wind induced potential sputtering to the lunar surface erosion rate and it's exosphere

NASA Astrophysics Data System (ADS)

Alnussirat, S. T.; Barghouty, A. F.; Edmunson, J. E.; Sabra, M. S.; Rickman, D. L.

2018-04-01

Sputtering of lunar regolith by solar-wind protons and heavy ions with kinetic energies of about 1 keV/amu is an important erosive process that affects the lunar surface and exosphere. It plays an important role in changing the chemical composition and thickness of the surface layer, and in introducing material into the exosphere. Kinetic sputtering is well modeled and understood, but understanding of mechanisms of potential sputtering has lagged behind. In this study we differentiate the contributions of potential sputtering from the standard (kinetic) sputtering in changing the chemical composition and erosion rate of the lunar surface. Also we study the contribution of potential sputtering in developing the lunar exosphere. Our results show that potential sputtering enhances the total characteristic sputtering erosion rate by about 44%, and reduces sputtering time scales by the same amount. Potential sputtering also introduces more material into the lunar exosphere.

Homogeneous reactions of hydrocarbons, silane, and chlorosilanes in radiofrequency plasmas at low pressures

NASA Technical Reports Server (NTRS)

Avni, R.; Carmi, U.; Inspektor, A.; Rosenthal, I.

1984-01-01

The ion-molecule and radical-molecule mechanisms are responsible for the dissociation of hydrocarbon, silane, and chlorosilane monomers and the formation of polymerized species, respectively, in an RF plasma discharge. In a plasma containing a mixture of monomer and argon the rate-determining step for both dissociation and polymerization is governed by an ion-molecule type of interaction. Adding hydrogen or ammonia to the monomer-argon mixture transforms the rate-determining step from an ion-molecule interaction to a radical-molecule interaction for both monomer dissociation and polymerization.

Structural and optical properties of gold-incorporated diamond-like carbon thin films deposited by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Majeed, Shahbaz; Siraj, K.; Naseem, S.; Khan, Muhammad F.; Irshad, M.; Faiz, H.; Mahmood, A.

2017-07-01

Pure and gold-doped diamond-like carbon (Au-DLC) thin films are deposited at room temperature by using RF magnetron sputtering in an argon gas-filled chamber with a constant flow rate of 100 sccm and sputtering time of 30 min for all DLC thin films. Single-crystal silicon (1 0 0) substrates are used for the deposition of pristine and Au-DLC thin films. Graphite (99.99%) and gold (99.99%) are used as co-sputtering targets in the sputtering chamber. The optical properties and structure of Au-DLC thin films are studied with the variation of gold concentration from 1%-5%. Raman spectroscopy, atomic force microscopy (AFM), Vickers hardness measurement (VHM), and spectroscopic ellipsometry are used to analyze these thin films. Raman spectroscopy indicates increased graphitic behavior and reduction in the internal stresses of Au-DLC thin films as the function of increasing gold doping. AFM is used for surface topography, which shows that spherical-like particles are formed on the surface, which agglomerate and form larger clusters on the surface by increasing the gold content. Spectroscopy ellipsometry analysis elucidates that the refractive index and extinction coefficient are inversely related and the optical bandgap energy is decreased with increasing gold content. VHM shows that gold doping reduces the hardness of thin films, which is attributed to the increase in sp2-hybridization.

Underlying role of mechanical rigidity and topological constraints in physical sputtering and reactive ion etching of amorphous materials

NASA Astrophysics Data System (ADS)

Bhattarai, Gyanendra; Dhungana, Shailesh; Nordell, Bradley J.; Caruso, Anthony N.; Paquette, Michelle M.; Lanford, William A.; King, Sean W.

2018-05-01

Analytical expressions describing ion-induced sputter or etch processes generally relate the sputter yield to the surface atomic binding energy (Usb) for the target material. While straightforward to measure for the crystalline elemental solids, Usb is more complicated to establish for amorphous and multielement materials due to composition-driven variations and incongruent sublimation. In this regard, we show that for amorphous multielement materials, the ion-driven yield can instead be better understood via a consideration of mechanical rigidity and network topology. We first demonstrate a direct relationship between Usb, bulk modulus, and ion sputter yield for the elements, and then subsequently prove our hypothesis for amorphous multielement compounds by demonstrating that the same relationships exist between the reactive ion etch (RIE) rate and nanoindentation Young's modulus for a series of a -Si Nx :H and a -Si OxCy :H thin films. The impact of network topology is further revealed via application of the Phillips-Thorpe theory of topological constraints, which directly relates the Young's modulus to the mean atomic coordination () for an amorphous solid. The combined analysis allows the trends and plateaus in the RIE rate to be ultimately reinterpreted in terms of the atomic structure of the target material through a consideration of . These findings establish the important underlying role of mechanical rigidity and network topology in ion-solid interactions and provide additional considerations for the design and optimization of radiation-hard materials in nuclear and outer space environments.

Bias in bonding behavior among boron, carbon, and nitrogen atoms in ion implanted a-BN, a-BC, and diamond like carbon films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genisel, Mustafa Fatih; Uddin, Md. Nizam; Say, Zafer

2011-10-01

In this study, we implanted N{sup +} and N{sub 2}{sup +} ions into sputter deposited amorphous boron carbide (a-BC) and diamond like carbon (DLC) thin films in an effort to understand the chemical bonding involved and investigate possible phase separation routes in boron carbon nitride (BCN) films. In addition, we investigated the effect of implanted C{sup +} ions in sputter deposited amorphous boron nitride (a-BN) films. Implanted ion energies for all ion species were set at 40 KeV. Implanted films were then analyzed using x-ray photoelectron spectroscopy (XPS). The changes in the chemical composition and bonding chemistry due to ion-implantationmore » were examined at different depths of the films using sequential ion-beam etching and high resolution XPS analysis cycles. A comparative analysis has been made with the results from sputter deposited BCN films suggesting that implanted nitrogen and carbon atoms behaved very similar to nitrogen and carbon atoms in sputter deposited BCN films. We found that implanted nitrogen atoms would prefer bonding to carbon atoms in the films only if there is no boron atom in the vicinity or after all available boron atoms have been saturated with nitrogen. Implanted carbon atoms also preferred to either bond with available boron atoms or, more likely bonded with other implanted carbon atoms. These results were also supported by ab-initio density functional theory calculations which indicated that carbon-carbon bonds were energetically preferable to carbon-boron and carbon-nitrogen bonds.« less

In vitro flow measurements in ion sputtered hydrocephalus shunts

NASA Technical Reports Server (NTRS)

Cho, Y. I.; Back, L. H.

1989-01-01

This paper describes an experimental procedure for accurate measurements of the pressure-drop/flow rate relationship in hydrocephalus shunts. Using a fish-hook arrangement, small flow rates in a perforated ion-sputtered Teflon microtubule were measured in vitro in a pressured system and were correlated with pressure in the system. Results indicate that appropriate drainage rates could be obtained in the physiological range for hydrocephalus shunts.

Ion bombardment and adsorption studies on ilmenite (FeTiO3) by X-ray photoelectron spectroscopy

NASA Technical Reports Server (NTRS)

Schulze, P. D.

1983-01-01

The effects of 5 KeV argon and oxygen ion bombardment on FeTiO3 (ilmenite) at low temperatures have been studied using X-ray photoelectron spectroscopy (XPS). Also, using this same technique, the adsorption of O2, NO, N2O, and CO at 300 K and the adsorption of O2 and D2O at 150K have been studied. Argon and oxygen ion bombardment of ilmenite have confirmed earlier studies on metal oxides that argon ions generally reduce the anion species while oxygen ions generally oxidize the anion species. The two iron states involved were Fe sup +2 and Fe sup O. The reduction of Ti sup +4 was not verified although a significant shift in the Ti(2p1,3) binding energies toward the metallic state was observed after oxygen ion bombardment at low temperatures. At temperatures above 150K, O2 adsorbs dissociatively on ilmenite while D2O adsorbs molecularly below 170K. Above 300 K No, N2O, and CO do not appear to adsorb dissociatively. Low temperature adsorption of D2O was found to be inhibited by predosing the ilmenite with O2.

Consistent kinetic simulation of plasma and sputtering in low temperature plasmas

NASA Astrophysics Data System (ADS)

Schmidt, Frederik; Trieschmann, Jan; Mussenbrock, Thomas

2016-09-01

Plasmas are commonly used in sputtering applications for the deposition of thin films. Although magnetron sources are a prominent choice, capacitively coupled plasmas have certain advantages (e.g., sputtering of non-conducting and/or ferromagnetic materials, aside of excellent control of the ion energy distribution). In order to understand the collective plasma and sputtering dynamics, a kinetic simulation model is helpful. Particle-in-Cell has been proven to be successful in simulating the plasma dynamics, while the Test-Multi-Particle-Method can be used to describe the sputtered neutral species. In this talk a consistent combination of these methods is presented by consistently coupling the simulated ion flux as input to a neutral particle transport model. The combined model is used to simulate and discuss the spatially dependent densities, fluxes and velocity distributions of all particles. This work is supported by the German Research Foundation (DFG) in the frame of Transregional Collaborative Research Center (SFB) TR-87.

High temperature strain gages

NASA Technical Reports Server (NTRS)

Gregory, Otto J. (Inventor); You, Tao (Inventor)

2011-01-01

A ceramic strain gage based on reactively sputtered indium-tin-oxide (ITO) thin films is used to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500.degree. C. A scanning electron microscopy (SEM) of the thick ITO sensors reveals a partially sintered microstructure comprising a contiguous network of submicron ITO particles with well defined necks and isolated nanoporosity. Densification of the ITO particles was retarded during high temperature exposure with nitrogen thus stabilizing the nanoporosity. ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established.

Multilayered Al/CuO thermite formation by reactive magnetron sputtering: Nano versus micro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrantoni, M.; Rossi, C.; Salvagnac, L.

2010-10-15

Multilayered Al/CuO thermite was deposited by a dc reactive magnetron sputtering method. Pure Al and Cu targets were used in argon-oxygen gas mixture plasma and with an oxygen partial pressure of 0.13 Pa. The process was designed to produce low stress (<50 MPa) multilayered nanoenergetic material, each layer being in the range of tens nanometer to one micron. The reaction temperature and heat of reaction were measured using differential scanning calorimetry and thermal analysis to compare nanostructured layered materials to microstructured materials. For the nanostructured multilayers, all the energy is released before the Al melting point. In the case ofmore » the microstructured samples at least 2/3 of the energy is released at higher temperatures, between 1036 and 1356 K.« less

Electrochemical properties of magnetron sputtered WO{sub 3} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madhavi, V.; Kondaiah, P.; Hussain, O. M.

2013-02-05

Thin films of tungsten oxide (WO{sub 3}) were deposited on ITO substrates by using RF magnetron sputtering at oxygen and argon atmospheres of 6 Multiplication-Sign 10{sup -2}Pa and 4 Pa respectively. The chemical composition and surface morphology of the WO{sub 3} thin films have been studied by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) respectively. The results indicate that the deposited WO{sub 3} thin films are nearly stoichiometric. The electrochemical performances of the WO{sub 3} thin films have been evaluated by galvonostatic charging/discharging method. The discharge capacity was 15{mu}Ah/cm{sup 2}{mu}m at the initial cycle and faded rapidly inmore » the first few cycles and stabilized at a lesser stage.« less

UHV LT-STM system with Sample and Tip Exchange

NASA Astrophysics Data System (ADS)

Dreyer, Michael; Lee, Jonghee; Wang, Hui; Sullivan, Dan; Barker, Barry

2006-03-01

We developed and built a low temperature scanning tunneling microscope system with ultra high vacuum sample and tip preparation capabilities. The STM is mounted inside an UHV can which is submerged in a He bath cryostat. The cryostat is equipped with two superconducting magnets allowing a maximum in plane field of 2 T and a maximum out of plane field of 9 T. The two fields can be combined to a 1 T vector field. The vacuum can is connected to an UHV system at room temperature consisting of two chambers: One dedicated to transferring samples and tips to the STM, and the other chamber used for tip/sample preparation. It is equipped with two electron beam evaporators, an argon ion sputter gun as well as sample heaters. The whole system is supported by an optical table to decouple the STM from building vibrations. The system was successfully used to study standing electron waves on gold (111) as well as vortices on NbSe2. Details of the microscope, sample and tip handling system, as well as the UHV system will be presented.

Preparation of Ag-containing diamond-like carbon films on the interior surface of tubes by a combined method of plasma source ion implantation and DC sputtering

NASA Astrophysics Data System (ADS)

Hatada, R.; Flege, S.; Bobrich, A.; Ensinger, W.; Dietz, C.; Baba, K.; Sawase, T.; Watamoto, T.; Matsutani, T.

2014-08-01

Adhesive diamond-like carbon (DLC) films can be prepared by plasma source ion implantation (PSII), which is also suitable for the treatment of the inner surface of a tube. Incorporation of a metal into the DLC film provides a possibility to change the characteristics of the DLC film. One source for the metal is DC sputtering. In this study PSII and DC sputtering were combined to prepare DLC films containing low concentrations of Ag on the interior surfaces of stainless steel tubes. A DLC film was deposited using a C2H4 plasma with the help of an auxiliary electrode inside of the tube. This electrode was then used as a target for the DC sputtering. A mixture of the gases Ar and C2H4 was used to sputter the silver. By changing the gas flow ratios and process time, the resulting Ag content of the films could be varied. Sample characterizations were performed by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, atomic force microscopy and Raman spectroscopy. Additionally, a ball-on-disk test was performed to investigate the tribological properties of the films. The antibacterial activity was determined using Staphylococcus aureus bacteria.

Crater function moments: Role of implanted noble gas atoms

NASA Astrophysics Data System (ADS)

Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

2018-04-01

Spontaneous pattern formation by energetic ion beams is usually explained in terms of surface-curvature dependent sputtering and atom redistribution in the target. Recently, the effect of ion implantation on surface stability has been studied for nonvolatile ion species, but for the case of noble gas ion beams it has always been assumed that the implanted atoms can be neglected. In this work, we show by molecular dynamics (MD) and Monte Carlo (MC) simulations that this assumption is not valid in a wide range of implant conditions. Sequential-impact MD simulations are performed for 1-keV Ar, 2-keV Kr, and 2-keV Xe bombardments of Si, starting with a pure single-crystalline Si target and running impacts until sputtering equilibrium has been reached. The simulations demonstrate the importance of the implanted ions for crater-function estimates. The atomic volumes of Ar, Kr, and Xe in Si are found to be a factor of two larger than in the solid state. To extend the study to a wider range of energies, MC simulations are performed. We find that the role of the implanted ions increases with the ion energy although the increase is attenuated for the heavier ions. The analysis uses the crater function formalism specialized to the case of sputtering equilibrium.

Verification of high efficient broad beam cold cathode ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdel Reheem, A. M., E-mail: amreheem2009@yahoo.com; Radiation Physics Department, National Center for Radiation Research and Technology; Ahmed, M. M.

2016-08-15

An improved form of cold cathode ion source has been designed and constructed. It consists of stainless steel hollow cylinder anode and stainless steel cathode disc, which are separated by a Teflon flange. The electrical discharge and output characteristics have been measured at different pressures using argon, nitrogen, and oxygen gases. The ion exit aperture shape and optimum distance between ion collector plate and cathode disc are studied. The stable discharge current and maximum output ion beam current have been obtained using grid exit aperture. It was found that the optimum distance between ion collector plate and ion exit aperturemore » is equal to 6.25 cm. The cold cathode ion source is used to deposit aluminum coating layer on AZ31 magnesium alloy using argon ion beam current which equals 600 μA. Scanning electron microscope and X-ray diffraction techniques used for characterizing samples before and after aluminum deposition.« less

Final Report: Mechanisms of sputter ripple formation: coupling among energetic ions, surface kinetics, stress and composition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chason, Eric; Shenoy, Vivek

Self-organized pattern formation enables the creation of nanoscale surface structures over large areas based on fundamental physical processes rather than an applied template. Low energy ion bombardment is one such method that induces the spontaneous formation of a wide variety of interesting morphological features (e.g., sputter ripples and/or quantum dots). This program focused on the processes controlling sputter ripple formation and the kinetics controlling the evolution of surfaces and nanostructures in high flux environments. This was done by using systematic, quantitative experiments to measure ripple formation under a variety of processing conditions coupled with modeling to interpret the results.

Solar Ion Processing of Major Element Surface Compositions of Mature Mare Soils: Insights from Combined XPS and Analytical TEM Observations

NASA Technical Reports Server (NTRS)

Christoffersen, R.; Dukes, C.; Keller, L. P.; Baragiola, R.

2012-01-01

Solar wind ions are capable of altering the sur-face chemistry of the lunar regolith by a number of mechanisms including preferential sputtering, radiation-enhanced diffusion and sputter erosion of space weathered surfaces containing pre-existing compositional profiles. We have previously reported in-situ ion irradiation experiments supported by X-ray photoelectron spectroscopy (XPS) and analytical TEM that show how solar ions potentially drive Fe and Ti reduction at the monolayer scale as well as the 10-100 nm depth scale in lunar soils [1]. Here we report experimental data on the effect of ion irradiation on the major element surface composition in a mature mare soil.

Room temperature ferromagnetism in Cu doped ZnO

NASA Astrophysics Data System (ADS)

Ali, Nasir; Singh, Budhi; Khan, Zaheer Ahmed; Ghosh, Subhasis

2018-05-01

We report the room temperature ferromagnetism in 2% Cu doped ZnO films grown by RF magnetron sputtering in different argon and oxygen partial pressure. X-ray photoelectron spectroscopy was used to ascertain the oxidation states of Cu in ZnO. The presence of defects within Cu-doped ZnO films can be revealed by electron paramagnetic resonance. It has been observed that saturated magnetic moment increase as we increase the zinc vacancies during deposition.

Ion-induced particle desorption in time-of-flight medium energy ion scattering

NASA Astrophysics Data System (ADS)

Lohmann, S.; Primetzhofer, D.

2018-05-01

Secondary ions emitted from solids upon ion impact are studied in a time-of-flight medium energy ion scattering (ToF-MEIS) set-up. In order to investigate characteristics of the emission processes and to evaluate the potential for surface and thin film analysis, experiments employing TiN and Al samples were conducted. The ejected ions exhibit a low initial kinetic energy of a few eV, thus, requiring a sufficiently high acceleration voltage for detection. Molecular and atomic ions of different charge states originating both from surface contaminations and the sample material are found, and relative yields of several species were determined. Experimental evidence that points towards a predominantly electronic sputtering process is presented. For emitted Ti target atoms an additional nuclear sputtering component is suggested.

Discontinuous model with semi analytical sheath interface for radio frequency plasma

NASA Astrophysics Data System (ADS)

Miyashita, Masaru

2016-09-01

Sumitomo Heavy Industries, Ltd. provide many products utilizing plasma. In this study, we focus on the Radio Frequency (RF) plasma source by interior antenna. The plasma source is expected to be high density and low metal contamination. However, the sputtering the antenna cover by high energy ion from sheath voltage still have been problematic. We have developed the new model which can calculate sheath voltage wave form in the RF plasma source for realistic calculation time. This model is discontinuous that electronic fluid equation in plasma connect to usual passion equation in antenna cover and chamber with semi analytical sheath interface. We estimate the sputtering distribution based on calculated sheath voltage waveform by this model, sputtering yield and ion energy distribution function (IEDF) model. The estimated sputtering distribution reproduce the tendency of experimental results.

Effects of Io ejecta on Europa

NASA Astrophysics Data System (ADS)

Eviatar, A.; Siscoe, G. L.; Johnson, T. V.; Matson, D. L.

1981-07-01

The effects of plasma ejected from Io on the nature and evolution of the surface of Europa and on the relative importance of the roles played by the two satellites in the Jupiter magnetosphere are examined. Observations of an ultraviolet absorption feature on the trailing side of Europa are interpreted as due to an equilibrium column density of SO2 in a steady-state model of the implantation of iogenic ions into the surface of Europa and their subsequent sputtering. The observed sulfur column density of 2 x 10 to the 16th/sq cm implies a slow loss of material from Europa, mainly water ice, and indicates that the spectrum of particles sputtered is soft. Considerations of the comparative roles of corotating and energetic heavy ions are shown to suggest that the implantation and sputtering is primarily the result of the proton and light ion component of the plasma. The weakness of Europa as a plasma source resulting from the soft sputtered particle spectrum thus leads to the dominance of Io in contributing to the magnetospheric plasma.

Hybrid-PIC simulation of sputtering product distribution in a Hall thruster

NASA Astrophysics Data System (ADS)

Cao, Xifeng; Hang, Guanrong; Liu, Hui; Meng, Yingchao; Luo, Xiaoming; Yu, Daren

2017-10-01

Hall thrusters have been widely used in orbit correction and the station-keeping of geostationary satellites due to their high specific impulse, long life, and high reliability. During the operating life of a Hall thruster, high-energy ions will bombard the discharge channel and cause serious erosion. As time passes, this sputtering process will change the macroscopic surface morphology of the discharge channel, especially near the exit, thus affecting the performance of the thruster. Therefore, it is necessary to carry out research on the motion of the sputtering products and erosion process of the discharge wall. To better understand the moving characteristics of sputtering products, based on the hybrid particle-in-cell (PIC) numerical method, this paper simulates the different erosion states of the thruster discharge channel in different moments and analyzes the moving process of different particles, such as B atoms and B+ ions. In this paper, the main conclusion is that B atoms are mainly produced on both sides of the channel exit, and B+ ions are mainly produced in the middle of the channel exit. The ionization rate of B atoms is approximately 1%.

Deuterium sputtering of Li and Li-O films

NASA Astrophysics Data System (ADS)

Nelson, Andrew; Buzi, Luxherta; Kaita, Robert; Koel, Bruce

2017-10-01

Lithium wall coatings have been shown to enhance the operational plasma performance of many fusion devices, including NSTX and other tokamaks, by reducing the global wall recycling coefficient. However, pure lithium surfaces are extremely difficult to maintain in experimental fusion devices due to both inevitable oxidation and codeposition from sputtering of hot plasma facing components. Sputtering of thin lithium and lithium oxide films on a molybdenum target by energetic deuterium ion bombardment was studied in laboratory experiments conducted in a surface science apparatus. A Colutron ion source was used to produce a monoenergetic, mass-selected ion beam. Measurements were made under ultrahigh vacuum conditions as a function of surface temperature (90-520 K) using x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and temperature programmed desorption (TPD). Results are compared with computer simulations conducted on a temperature-dependent data-calibrated (TRIM) model.

A hybrid electron cyclotron resonance metal ion source with integrated sputter magnetron for the production of an intense Al{sup +} ion beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weichsel, T., E-mail: tim.weichsel@fep.fraunhofer.de; Hartung, U.; Kopte, T.

2015-09-15

A metal ion source prototype has been developed: a combination of magnetron sputter technology with 2.45 GHz electron cyclotron resonance (ECR) ion source technology—a so called magnetron ECR ion source (MECRIS). An integrated ring-shaped sputter magnetron with an Al target is acting as a powerful metal atom supply in order to produce an intense current of singly charged metal ions. Preliminary experiments show that an Al{sup +} ion current with a density of 167 μA/cm{sup 2} is extracted from the source at an acceleration voltage of 27 kV. Spatially resolved double Langmuir probe measurements and optical emission spectroscopy were usedmore » to study the plasma states of the ion source: sputter magnetron, ECR, and MECRIS plasma. Electron density and temperature as well as Al atom density were determined as a function of microwave and sputter magnetron power. The effect of ECR heating is strongly pronounced in the center of the source. There the electron density is increased by one order of magnitude from 6 × 10{sup 9} cm{sup −3} to 6 × 10{sup 10} cm{sup −3} and the electron temperature is enhanced from about 5 eV to 12 eV, when the ECR plasma is ignited to the magnetron plasma. Operating the magnetron at constant power, it was observed that its discharge current is raised from 1.8 A to 4.8 A, when the ECR discharge was superimposed with a microwave power of 2 kW. At the same time, the discharge voltage decreased from about 560 V to 210 V, clearly indicating a higher plasma density of the MECRIS mode. The optical emission spectrum of the MECRIS plasma is dominated by lines of excited Al atoms and shows a significant contribution of lines arising from singly ionized Al. Plasma emission photography with a CCD camera was used to prove probe measurements and to identify separated plasma emission zones originating from the ECR and magnetron discharge.« less

Experimental investigations of argon and xenon ion sources

NASA Technical Reports Server (NTRS)

Kaufman, H. R.

1975-01-01

The multipole thruster was used to investigate the use of argon and xenon propellants as possible alternatives to the electric thruster propellants of mercury and cesium. The multipole approach was used because of its general high performance level. The design employed, using flat and cylindrical rolled sections of sheet metal, was selected for ease of fabrication, design, assembly, and modification. All testing was conducted in a vacuum facility and the pumping was accomplished by a 0.8 m diffusion pump together with liquid nitrogen cooled liner. Minimum discharge losses were in the 200-250 ev. ion range for both argon and xenon. Flatness parameters were typically in the 0.70-0.75 range.

Laser ablation of human atherosclerotic plaque without adjacent tissue injury

NASA Technical Reports Server (NTRS)

Grundfest, W. S.; Litvack, F.; Forrester, J. S.; Goldenberg, T.; Swan, H. J. C.

1985-01-01

Seventy samples of human cadaver atherosclerotic aorta were irradiated in vitro using a 308 nm xenon chloride excimer laser. Energy per pulse, pulse duration and frequency were varied. For comparison, 60 segments were also irradiated with an argon ion and an Nd:YAG laser operated in the continuous mode. Tissue was fixed in formalin, sectioned and examined microscopically. The Nd:YAG and argon ion-irradiated tissue exhibited a central crater with irregular edges and concentric zones of thermal and blast injury. In contrast, the excimer laser-irradiated tissue had narrow deep incisions with minimal or no thermal injury. These preliminary experiments indicate that the excimer laser vaporizes tissue in a manner different from that of the continuous wave Nd:YAG or argon ion laser. The sharp incision margins and minimal damage to adjacent normal tissue suggest that the excimer laser is more desirable for general surgical and intravascular uses than are the conventionally used medical lasers.

On the SIMS Ionization Probability of Organic Molecules.

PubMed

Popczun, Nicholas J; Breuer, Lars; Wucher, Andreas; Winograd, Nicholas

2017-06-01

The prospect of improved secondary ion yields for secondary ion mass spectrometry (SIMS) experiments drives innovation of new primary ion sources, instrumentation, and post-ionization techniques. The largest factor affecting secondary ion efficiency is believed to be the poor ionization probability (α + ) of sputtered material, a value rarely measured directly, but estimated to be in some cases as low as 10 -5 . Our lab has developed a method for the direct determination of α + in a SIMS experiment using laser post-ionization (LPI) to detect neutral molecular species in the sputtered plume for an organic compound. Here, we apply this method to coronene (C 24 H 12 ), a polyaromatic hydrocarbon that exhibits strong molecular signal during gas-phase photoionization. A two-dimensional spatial distribution of sputtered neutral molecules is measured and presented. It is shown that the ionization probability of molecular coronene desorbed from a clean film under bombardment with 40 keV C 60 cluster projectiles is of the order of 10 -3 , with some remaining uncertainty arising from laser-induced fragmentation and possible differences in the emission velocity distributions of neutral and ionized molecules. In general, this work establishes a method to estimate the ionization efficiency of molecular species sputtered during a single bombardment event. Graphical Abstract .

Formation and characterization of perpendicular mode Si ripples by glancing angle O{sub 2}{sup +} sputtering at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mollick, S. A.; Ghose, D.

Off-normal low energy ion beam sputtering of solid surfaces often leads to morphological instabilities resulting in the spontaneous formation of ripple structures in nanometer length scales. In the case of Si surfaces at ambient temperature, ripple formation is found to take place normally at lower incident angles with the wave vector parallel to the ion beam direction. The absence of ripple pattern on Si surface at larger angles is due to the dominance of ion beam polishing effect. We have shown that a gentle chemical roughening of the starting surface morphology can initiate ripple pattern under grazing incidence ion beammore » sputtering (theta>64 deg. with respect to the surface normal), where the ripple wave vector is perpendicular to the ion beam direction. The characteristics of the perpendicular mode ripples are studied as a function of pristine surface roughness (2-30 nm) and projectile fluence (5x10{sup 16}-1.5x10{sup 18} O atoms cm{sup -2}). The quality of the morphological structure is assessed from the analysis of ion induced topological defects.« less

Reduced atomic shadowing in HiPIMS: Role of the thermalized metal ions

NASA Astrophysics Data System (ADS)

Oliveira, João Carlos; Ferreira, Fábio; Anders, André; Cavaleiro, Albano

2018-03-01

In magnetron sputtering, the ability to tailor film properties depends primarily on the control of the flux of particles impinging on the growing film. Among deposition mechanisms, the shadowing effect leads to the formation of a rough surface and a porous, columnar microstructure. Re-sputtered species may be re-deposited in the valleys of the films surface and thereby contribute to a reduction of roughness and to fill the underdense regions. Both effects are non-local and they directly compete to shape the final properties of the deposited films. Additional control of the bombarding flux can be obtained by ionizing the sputtered flux, because ions can be controlled with respect to their energy and impinging direction, such as in High-Power Impulse Magnetron Sputtering (HiPIMS). In this work, the relation between ionization of the sputtered species and thin film properties is investigated in order to identify the mechanisms which effectively influence the shadowing effect in Deep Oscillation Magnetron Sputtering (DOMS), a variant of HiPIMS. The properties of two Cr films deposited using the same averaged target power by d.c. magnetron sputtering and DOMS have been compared. Additionally, the angle distribution of the Cr species impinging on the substrate was simulated using Monte Carlo-based programs while the energy distribution of the energetic particles bombarding the substrate was evaluated by energy-resolved mass analysis. It was found that the acceleration of the thermalized chromium ions at the substrate sheath in DOMS significantly reduces the high angle component of their impinging angle distribution and, thus, efficiently reduces atomic shadowing. Therefore, a high degree of ionization in HiPIMS results in almost shadowing effect-free film deposition and allows us to deposit dense and compact films without the need of high energy particle bombardment during growth.

Stimulated Desorption from Icy Aerosol Particles: A Possible Relevance To Titan's Ionospheric Conditions

NASA Astrophysics Data System (ADS)

Bordalo, Vinicius; Mejia, Christian; da Silveira, Enio F.; Seperuelo Duarte, Eduardo; Pilling, Sergio

Saturn's largest moon, Titan, has a dense atmosphere primarily composed of molecular nitro-gen (N2 , 96%) and methane (CH4 , 4%). Its atmospheric structure has been intensively studied recently due to the large amount of data obtained in situ by the Huygens probe during its de-cent to the surface on 14 January 2005. The probe could diagnose the composition of the haze particles made up organic chains containing H, C and N. Hydrocarbons and nitriles produced by photolysis of CH4 at high altitudes (˜ 2,000 km) act as embryos of aerosols of Titan as they fall to the surface. It is expected that CH4 condenses on these particles forming a layer of ice by adsorption or nucleation. Due to the high abundance of these aerosols throughout the atmo-sphere of Titan, their presence are relevant for the ionic balance of the atmosphere, especially the lower ionosphere promoted mainly by the flux of galactic cosmic rays (GCR). We have investigated the production of ions by electronic sputtering process due to the bombardment of the surfaces of aerosols by heavy ions. Time-of-flight (TOF) technique was used to obtain ion sputtering yields. An ice layer of CH4 was grown by condensation over a pre-condensed N2 ice in high vacuum chamber (1 × 10-7 mbar) at cryogenic temperature (10 K). Relative sputtering yields due to fast projectiles (252 Cf fission fragment ˜ 65 MeV) on the ice surfaces were measured. The bombardment was continued during the successive growth of both con-densed layers; the negative and positive sputtered ions were identified by TOF. Hybrid species including NH+ (17 u), HCN+ (27 u) and CN- (26 u) were formed, as well as the acetonitrile 3 ion (CH3 CN+ , 41 u). We argue that a similar process of continued ion replenishment into the gas phase by sputtering in aerosols ubiquitous in the lower ionosphere of Titan may occur and should be further investigated.

Large-area, continuous and high electrical performances of bilayer to few layers MoS2 fabricated by RF sputtering via post-deposition annealing method

PubMed Central

Hussain, Sajjad; Singh, Jai; Vikraman, Dhanasekaran; Singh, Arun Kumar; Iqbal, Muhammad Zahir; Khan, Muhammad Farooq; Kumar, Pushpendra; Choi, Dong-Chul; Song, Wooseok; An, Ki-Seok; Eom, Jonghwa; Lee, Wan-Gyu; Jung, Jongwan

2016-01-01

We report a simple and mass-scalable approach for thin MoS2 films via RF sputtering combined with the post-deposition annealing process. We have prepared as-sputtered film using a MoS2 target in the sputtering system. The as-sputtered film was subjected to post-deposition annealing to improve crystalline quality at 700 °C in a sulfur and argon environment. The analysis confirmed the growth of continuous bilayer to few-layer MoS2 film. The mobility value of ~29 cm2/Vs and current on/off ratio on the order of ~104 were obtained for bilayer MoS2. The mobility increased up to ~173–181 cm2/Vs, respectively, for few-layer MoS2. The mobility of our bilayer MoS2 FETs is larger than any previously reported values of single to bilayer MoS2 grown on SiO2/Si substrate with a SiO2 gate oxide. Moreover, our few-layer MoS2 FETs exhibited the highest mobility value ever reported for any MoS2 FETs with a SiO2 gate oxide. It is presumed that the high mobility behavior of our film could be attributed to low charged impurities of our film and dielectric screening effect by an interfacial MoOxSiy layer. The combined preparation route of RF sputtering and post-deposition annealing process opens up the novel possibility of mass and batch production of MoS2 film. PMID:27492282

One-dimensional analysis of the rate of plasma-assisted sputter deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmero, A.; Rudolph, H.; Habraken, F. H. P. M.

2007-04-15

In this article a recently developed model [A. Palmero, H. Rudolph, and F. H. P. M. Habraken, Appl. Phys. Lett. 89, 211501 (2006)] is applied to analyze the transport of sputtered material from the cathode toward the growing film when using a plasma-assisted sputtering deposition technique. The argon pressure dependence of the deposition rate of aluminum, silicon, vanadium, chromium, germanium, tantalum, and tungsten under several different experimental conditions has been analyzed by fitting experimental results from the literature to the above-mentioned theory. Good fits are obtained. Three quantities are deduced from the fit: the temperature of the cathode and ofmore » the growing film, and the value of the effective cross section for thermalization due to elastic scattering of a sputtered particle on background gas atoms. The values derived from the fits for the growing film and cathode temperature are very similar to those experimentally determined and reported in the literature. The effective cross sections have been found to be approximately the corresponding geometrical cross section divided by the average number of collisions required for the thermalization, implying that the real and effective thermalization lengths have a similar value. Finally, the values of the throw distance appearing in the Keller-Simmons model, as well as its dependence on the deposition conditions have been understood invoking the values of the cathode and film temperature, as well as of the value of the effective cross section. The analysis shows the overall validity of this model for the transport of sputtered particles in sputter deposition.« less

Dedicated Co-deposition System for Metallic Paramagnetic Films

DOE PAGES

Jaeckel, F.; Kotsubo, V.; Hall, J. A.; ...

2012-01-27

Here, we describe a dedicated co-sputtering/ion-mill system developed to study metallic paramagnetic films for use in magnetic microcalorimetry. Small-diameter sputtering guns allow study of several precious-metal-based paramagnetic alloy systems within a reasonable budget. We demonstrated safe operation of a 1" sputtering gun at >5x the rated maximum power, achieving deposition rates up to ~900 Å/min/gun (Cu) in our co-sputtering geometry. Demonstrated co-sputtering deposition ratios up to 100:1 allow accurate tuning of magnetic dopant concentration and eliminate the difficulty of preparing homogeneous alloy targets of extreme dilution.

Measurement of plasma decay processes in mixture of sodium and argon by coherent microwave scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Zhili; Shneider, Mikhail N.

2010-03-15

This paper presents the experimental measurement and computational model of sodium plasma decay processes in mixture of sodium and argon by using radar resonance-enhanced multiphoton ionization (REMPI), coherent microwave Rayleigh scattering of REMPI. A single laser beam resonantly ionizes the sodium atoms by means of 2+1 REMPI process. The laser beam can only generate the ionization of the sodium atoms and have negligible ionization of argon. Coherent microwave scattering in situ measures the total electron number in the laser-induced plasma. Since the sodium ions decay by recombination with electrons, microwave scattering directly measures the plasma decay processes of the sodiummore » ions. A theoretical plasma dynamic model, including REMPI of the sodium and electron avalanche ionization (EAI) of sodium and argon in the gas mixture, has been developed. It confirms that the EAI of argon is several orders of magnitude lower than the REMPI of sodium. The theoretical prediction made for the plasma decay process of sodium plasma in the mixture matches the experimental measurement.« less

Whiskers, cones and pyramids created in sputtering by ion bombardment

NASA Technical Reports Server (NTRS)

Wehner, G. K.

1979-01-01

A thorough study of the role which foreign atoms play in cone formation during sputtering of metals revealed many experimental facts. Two types of cone formation were distinquished, deposit cones and seed cones. Twenty-six combinations of metals for seed cone formation were tested. The sputtering yield variations with composition for combinations which form seed cones were measured. It was demonstrated that whisker growth becomes a common occurrence when low melting point material is sputter deposited on a hot nonsputtered high melting point electrode.

A pulsed supersonic entrainment reactor for the rational preparation of cold ionic complexes

NASA Astrophysics Data System (ADS)

Robertson, W. H.; Kelley, J. A.; Johnson, M. A.

2000-12-01

We describe an ion source for the efficient preparation of cold ion-molecule complexes, X-ṡM. The method relies on condensation of solvent molecules, M, onto argon-solvated ions, X-ṡArm, where the X-ṡArm species are formed in a primary expansion and the molecular partner, M, is interfaced to this flow in the hydrodynamic region by supersonic entrainment. This hybrid "supersonic afterglow" reactor provides a clean synthetic approach for both bare and argon-solvated complexes, where the latter are particularly useful since their structures can be characterized by "nanomatrix" infrared predissociation spectroscopy.

The Influence of Drift Gas Composition on the Separation Mechanism in Traveling Wave Ion Mobility Spectrometry: Insight from Electrodynamic Simulations

PubMed Central

May, Jody C.; McLean, John A.

2013-01-01

The influence of three different drift gases (helium, nitrogen, and argon) on the separation mechanism in traveling wave ion mobility spectrometry is explored through ion trajectory simulations which include considerations for ion diffusion based on kinetic theory and the electrodynamic traveling wave potential. The model developed for this work is an accurate depiction of a second-generation commercial traveling wave instrument. Three ion systems (cocaine, MDMA, and amphetamine) whose reduced mobility values have previously been measured in different drift gases are represented in the simulation model. The simulation results presented here provide a fundamental understanding of the separation mechanism in traveling wave, which is characterized by three regions of ion motion: (1) ions surfing on a single wave, (2) ions exhibiting intermittent roll-over onto subsequent waves, and (3) ions experiencing a steady state roll-over which repeats every few wave cycles. These regions of ion motion are accessed through changes in the gas pressure, wave amplitude, and wave velocity. Resolving power values extracted from simulated arrival times suggest that momentum transfer in helium gas is generally insufficient to access regions (2) and (3) where ion mobility separations occur. Ion mobility separations by traveling wave are predicted to be effectual for both nitrogen and argon, with slightly lower resolving power values observed for argon as a result of band-broadening due to collisional scattering. For the simulation conditions studied here, the resolving power in traveling wave plateaus between regions (2) and (3), with further increases in wave velocity contributing only minor improvements in separations. PMID:23888124

The Influence of Drift Gas Composition on the Separation Mechanism in Traveling Wave Ion Mobility Spectrometry: Insight from Electrodynamic Simulations.

PubMed

May, Jody C; McLean, John A

2003-06-01

The influence of three different drift gases (helium, nitrogen, and argon) on the separation mechanism in traveling wave ion mobility spectrometry is explored through ion trajectory simulations which include considerations for ion diffusion based on kinetic theory and the electrodynamic traveling wave potential. The model developed for this work is an accurate depiction of a second-generation commercial traveling wave instrument. Three ion systems (cocaine, MDMA, and amphetamine) whose reduced mobility values have previously been measured in different drift gases are represented in the simulation model. The simulation results presented here provide a fundamental understanding of the separation mechanism in traveling wave, which is characterized by three regions of ion motion: (1) ions surfing on a single wave, (2) ions exhibiting intermittent roll-over onto subsequent waves, and (3) ions experiencing a steady state roll-over which repeats every few wave cycles. These regions of ion motion are accessed through changes in the gas pressure, wave amplitude, and wave velocity. Resolving power values extracted from simulated arrival times suggest that momentum transfer in helium gas is generally insufficient to access regions (2) and (3) where ion mobility separations occur. Ion mobility separations by traveling wave are predicted to be effectual for both nitrogen and argon, with slightly lower resolving power values observed for argon as a result of band-broadening due to collisional scattering. For the simulation conditions studied here, the resolving power in traveling wave plateaus between regions (2) and (3), with further increases in wave velocity contributing only minor improvements in separations.

Formation of silicon nanodots via ion beam sputtering of ultrathin gold thin film coatings on Si

PubMed Central

2011-01-01

Ion beam sputtering of ultrathin film Au coatings used as a physical catalyst for self-organization of Si nanostructures has been achieved by tuning the incident particle energy. This approach holds promise as a scalable nanomanufacturing parallel processing alternative to candidate nanolithography techniques. Structures of 11- to 14-nm Si nanodots are formed with normal incidence low-energy Ar ions of 200 eV and fluences above 2 × 1017 cm-2. In situ surface characterization during ion irradiation elucidates early stage ion mixing migration mechanism for nanodot self-organization. In particular, the evolution from gold film islands to the formation of ion-induced metastable gold silicide followed by pure Si nanodots formed with no need for impurity seeding. PMID:21711934

Electrical properties of Si-Si interfaces obtained by room temperature covalent wafer bonding

NASA Astrophysics Data System (ADS)

Jung, A.; Zhang, Y.; Arroyo Rojas Dasilva, Y.; Isa, F.; von Känel, H.

2018-02-01

We study covalent bonds between p-doped Si wafers (resistivity ˜10 Ω cm) fabricated on a recently developed 200 mm high-vacuum system. Oxide- and void free interfaces were obtained by argon (Ar) or neon (Ne) sputtering prior to wafer bonding at room temperature. The influence of the sputter induced amorphous Si layer at the bonding interface on the electrical behavior is accessed with temperature-dependent current-voltage measurements. In as-bonded structures, charge transport is impeded by a potential barrier of 0.7 V at the interface with thermionic emission being the dominant charge transport mechanism. Current-voltage characteristics are found to be asymmetric which can tentatively be attributed to electric dipole formation at the interface as a result of the time delay between the surface preparation of the two bonding partners. Electron beam induced current measurements confirm the corresponding asymmetric double Schottky barrier like band-alignment. Moreover, we demonstrate that defect annihilation at a low temperature of 400 °C increases the electrical conductivity by up to three orders of magnitude despite the lack of recrystallization of the amorphous layer. This effect is found to be more pronounced for Ne sputtered surfaces which is attributed to the lighter atomic mass compared to Ar, inducing weaker lattice distortions during the sputtering.

A new setup for experimental investigations of solar wind sputtering

NASA Astrophysics Data System (ADS)

Szabo, Paul S.; Berger, Bernhard M.; Chiba, Rimpei; Stadlmayr, Reinhard; Aumayr, Friedrich

2017-04-01

The surfaces of Mercury and Moon are not shielded by a thick atmosphere and therefore they are exposed to bombardment by charged particles, ultraviolet photons and micrometeorites. These influences lead to an alteration and erosion of the surface, and the emitted atoms and molecules form a thin atmosphere, an exosphere, around these celestial bodies [1]. The composition of these exospheres is connected to the surface composition and has been subject to flyby measurements by satellites. Model calculations which include the erosion mechanisms can be used as a method of comparison for such exosphere measurements and allow conclusions about the surface composition. Surface sputtering induced by solar wind ions hereby represents a major contribution to the erosion of the surfaces of Mercury and Moon [1]. However, the experimental database for sputtering of respective analogue materials by solar wind ions, which would be necessary for exact modelling of the space weathering process, is still in its early stages. Sputtering experiments have been performed at TU Wien during the past years using a quartz crystal microbalance (QCM) technique [2]. Target material is deposited on the quartz surface as a thin layer and the quartz's resonance frequency is measured under ion bombardment. The sputter yield can then be calculated from the frequency change and the ion current [2]. In order to remove the restrictions of a thin layer QCM target and simplify experiments with composite targets, a new QCM catcher setup was developed. In the new design, the QCM is placed beside the target holder and acts as a catcher for material that is sputtered from the target surface. By comparing the catcher signal to reference measurements and SDTrimSP simulations [3], the target sputter yield can be determined. In order to test the setup, we have performed experiments with a Au-coated QCM target under 2 keV Ar+ bombardment so that both the mass changes at the target and at the catcher could be obtained simultaneously. The results coincide very well with SDTrimSP predictions showing the feasibility of the new design [4]. Furthermore, Fe-coated QCM targets with different surface roughness were investigated in the new setup. The surface roughness represents a key factor for the solar wind induced erosion of planetary or lunar rocks. It has a strong influence on the absolute sputtering yield as well as on the spatial distribution of sputtered particles and was therefore investigated. As a next step, sputtering experiments with Mercury or Moon analogues will be conducted. Knowledge gained in the course of this research will enhance the understanding of surface sputtering by solar wind ions and used to improve theoretical models of the Mercury's and Moon's exosphere formation. References: [1] E. Kallio, et al., Planetary and Space Science, 56, 1506 (2008). [2] G. Hayderer, et al., Review of Scientific Instruments, 70, 3696 (1999). [3] A. Mutzke, R. Schneider, W. Eckstein, R. Dohmen, SDTrimSP: Version 5.00, IPP Report, 12/8, (2011). [4] B. M. Berger, P. S. Szabo, R. Stadlmayr, F. Aumayr, Nucl. Instrum. Meth. Phys. Res. B, doi: 10.1016/j.nimb.2016.11.039

A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

DOE PAGES

Anders, André

2014-09-02

In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in thismore » review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.« less

Investigating the Fundamentals of Molecular Depth Profiling Using Strong-field Photoionization of Sputtered Neutrals

PubMed Central

Willingham, D.; Brenes, D. A.; Winograd, N.; Wucher, A.

2010-01-01

Molecular depth profiles of model organic thin films were performed using a 40 keV C60+ cluster ion source in concert with TOF-SIMS. Strong-field photoionization of intact neutral molecules sputtered by 40 keV C60+ primary ions was used to analyze changes in the chemical environment of the guanine thin films as a function of ion fluence. Direct comparison of the secondary ion and neutral components of the molecular depth profiles yields valuable information about chemical damage accumulation as well as changes in the molecular ionization probability. An analytical protocol based on the erosion dynamics model is developed and evaluated using guanine and trehalose molecular secondary ion signals with and without comparable laser photoionization data. PMID:26269660

Advanced ion thruster research

NASA Technical Reports Server (NTRS)

Wilbur, P. J.

1984-01-01

A simple model describing the discharge chamber performance of high strength, cusped magnetic field ion thrusters is developed. The model is formulated in terms of the energy cost of producing ions in the discharge chamber and the fraction of ions produced in the discharge chamber that are extracted to form the ion beam. The accuracy of the model is verified experimentally in a series of tests wherein the discharge voltage, propellant, grid transparency to neutral atoms, beam diameter and discharge chamber wall temperature are varied. The model is exercised to demonstrate what variations in performance might be expected by varying discharge chamber parameters. The results of a study of xenon and argon orificed hollow cathodes are reported. These results suggest that a hollow cathode model developed from research conducted on mercury cathodes can also be applied to xenon and argon. Primary electron mean free paths observed in argon and xenon cathodes that are larger than those found in mercury cathodes are identified as a cause of performance differences between mercury and inert gas cathodes. Data required as inputs to the inert gas cathode model are presented so it can be used as an aid in cathode design.

The Deposition of Multicomponent Films for Electrooptic Applications via a Computer Controlled Dual Ion Beam Sputtering System

DTIC Science & Technology

1991-12-31

AD-A252 218 The Deposition of Multicomponent Films for Electrooptic Applications via a Computer Controlled Dual Ion Beam Sputtering System ONR...6 3 2. Deposition of Electrooptic Thin Films ................................... 11 3. High Resolution Imaging of Twin and Antiphase...Domain Boundaries in Perovskite KNbO3 Thin Films .......... 30 4. Microstructural Characterization of the Epitaxial3 (111) KNbO3 on (0001) Sapphire

Fabrication of Nanoscaled Systems

DTIC Science & Technology

2007-05-01

corresponds to an effective dose as low as a few ýC/cm2 for sputtering of a 50 rum resist film. Comparison to observed sputtering rates in other polymeric ...materials (e.g. polystyrene and AZ and SU8 resists), coupled with time of flight SIMS measurements indicate that the relevant mechanism is indeed ion...approximately unity between GMR substrate and resist (for both electron and ion exposed HSQ), which we would not expect to be attainable using polymeric

Verification of the sputter-generated 32SFn- (n = 1-6) anions by accelerator mass spectrometry

NASA Astrophysics Data System (ADS)

Mane, R. G.; Surendran, P.; Kumar, Sanjay; Nair, J. P.; Yadav, M. L.; Hemalatha, M.; Thomas, R. G.; Mahata, K.; Kailas, S.; Gupta, A. K.

2016-01-01

Recently, we have performed systematic Secondary Ion Mass Spectrometry (SIMS) measurements at our ion source test set up and have demonstrated that gas phase 32SFn- (n = 1-6) anions for all size 'n' can be readily generated from a variety of surfaces undergoing Cs+ ion sputtering in the presence of high purity SF6 gas by employing the gas spray-cesium sputter technique. In our SIMS measurements, the isotopic yield ratio 34SFn-/32SFn- (n = 1-6) was found to be close to its natural abundance but not for all size 'n'. In order to gain further insight into the constituents of these molecular anions, ultra sensitive Accelerator Mass Spectrometry (AMS) measurements were conducted with the most abundant 32SFn- (n = 1-6) anions, at BARC-TIFR 14 UD Pelletron accelerator. The results from these measurements are discussed in this paper.

Testing and Analysis of NEXT Ion Engine Discharge Cathode Assembly Wear

NASA Technical Reports Server (NTRS)

Domonkos, Matthew T.; Foster, John E.; Soulas, George C.; Nakles, Michael

2003-01-01

Experimental and analytical investigations were conducted to predict the wear of the discharge cathode keeper in the NASA Evolutionary Xenon Thruster. The ion current to the keeper was found to be highly dependent upon the beam current, and the average beam current density was nearly identical to that of the NSTAR thruster for comparable beam current density. The ion current distribution was highly peaked toward the keeper orifice. A deterministic wear assessment predicted keeper orifice erosion to the same diameter as the cathode tube after processing 375 kg of xenon. A rough estimate of discharge cathode assembly life limit due to sputtering indicated that the current design exceeds the qualification goal of 405 kg. Probabilistic wear analysis showed that the plasma potential and the sputter yield contributed most to the uncertainty in the wear assessment. It was recommended that fundamental experimental and modeling efforts focus on accurately describing the plasma potential and the sputtering yield.

Additive patterning of ion-beam-sputtered non-conformal Ni80Fe20 and Co70Fe30 magnetic films

NASA Astrophysics Data System (ADS)

Redondo, C.; Moralejo, S.; Castaño, F.; Lee, W.; Nielsch, K.; Ross, C. A.; Castaño, F. J.

2006-04-01

Additive patterning processes of magnetic films grown using an ion-beam sputter (IBS) system designed to produce non-conformal films are described. The effects of the ion-gun beam current and Ar pressure on the sputtering rates and roughness of Ni80Fe20 and Co70Fe30 magnetic thin films are investigated using atomic-force microscopy (AFM) and the films' magnetic properties are measured using spatially resolved magneto-optical magnetometry. By tailoring the plasma solid angle, non-conformal film growth allows for simple additive patterning down to lateral dimensions ranging from a few microns to the deep-submicron regime, using templates defined by photolithography or electron-beam lithography, and shadow masks created using templated self-assembly. The magnetization reversal exhibited by patterned sub-200 nm nanodisc arrays with different lateral edge-roughness will be discussed.

Effect of nitrogen doping on structural, morphological, optical and electrical properties of radio frequency magnetron sputtered zinc oxide thin films

NASA Astrophysics Data System (ADS)

Perumal, R.; Hassan, Z.

2016-06-01

Zinc oxide receives remarkable attention due to its several attractive physical properties. Zinc oxide thin films doped with nitrogen were grown by employing RF magnetron sputtering method at room temperature. Doping was accomplished in gaseous medium by mixing high purity nitrogen gas along with argon sputtering gas. Structural studies confirmed the high crystalline nature with c-axis oriented growth of the nitrogen doped zinc oxide thin films. The tensile strain was developed due to the incorporation of the nitrogen into the ZnO crystal lattice. Surface roughness of the grown films was found to be decreased with increasing doping level was identified through atomic force microscope analysis. The presenting phonon modes of each film were confirmed through FTIR spectral analysis. The increasing doping level leads towards red-shifting of the cut-off wavelength due to decrement of the band gap was identified through UV-vis spectroscopy. All the doped films exhibited p-type conductivity was ascertained using Hall measurements and the obtained results were presented.

Heated probe diagnostic inside of the gas aggregation nanocluster source

NASA Astrophysics Data System (ADS)

Kolpakova, Anna; Shelemin, Artem; Kousal, Jaroslav; Kudrna, Pavel; Tichy, Milan; Biederman, Hynek; Surface; Plasma Science Team

2016-09-01

Gas aggregation cluster sources (GAS) usually operate outside common working conditions of most magnetrons and the size of nanoparticles created in GAS is below that commonly studied in dusty plasmas. Therefore, experimental data obtained inside the GAS are important for better understanding of process of nanoparticles formation. In order to study the conditions inside the gas aggregation chamber, special ``diagnostic GAS'' has been constructed. It allows simultaneous monitoring (or spatial profiling) by means of optical emission spectroscopy, mass spectrometry and probe diagnostic. Data obtained from Langmuir and heated probes map the plasma parameters in two dimensions - radial and axial. Titanium has been studied as an example of metal for which the reactive gas in the chamber starts nanoparticles production. Three basic situations were investigated: sputtering from clean titanium target in argon, sputtering from partially pre-oxidized target and sputtering with oxygen introduced into the discharge. It was found that during formation of nanoparticles the plasma parameters differ strongly from the situation without nanoparticles. These experimental data will support the efforts of more realistic modeling of the process. Czech Science Foundation 15-00863S.

Development of low-stress Iridium coatings for astronomical x-ray mirrors

NASA Astrophysics Data System (ADS)

Döhring, Thorsten; Probst, Anne-Catherine; Stollenwerk, Manfred; Wen, Mingwu; Proserpio, Laura

2016-07-01

Previously used mirror technologies are not suitable for the challenging needs of future X-ray telescopes. This is why the required high precision mirror manufacturing triggers new technical developments around the world. Some aspects of X-ray mirrors production are studied within the interdisciplinary project INTRAAST, a German acronym for "industry transfer of astronomical mirror technologies". The project is embedded in a cooperation of Aschaffenburg University of Applied Sciences and the Max-Planck-Institute for extraterrestrial Physics. One important task is the development of low-stress Iridium coatings for X-ray mirrors based on slumped thin glass substrates. The surface figure of the glass substrates is measured before and after the coating process by optical methods. Correlating the surface shape deformation to the parameters of coating deposition, here especially to the Argon sputtering pressure, allows for an optimization of the process. The sputtering parameters also have an influence on the coating layer density and on the micro-roughness of the coatings, influencing their X-ray reflection properties. Unfortunately the optimum coating process parameters seem to be contrarious: low Argon pressure resulted in better micro-roughness and higher density, whereas higher pressure leads to lower coating stress. Therefore additional measures like intermediate coating layers and temperature treatment will be considered for further optimization. The technical approach for the low-stress Iridium coating development, the experimental equipment, and the obtained first experimental results are presented within this paper.

Thick c-BN films deposited by radio frequency magnetron sputtering in argon/nitrogen gas mixture with additional hydrogen gas

NASA Astrophysics Data System (ADS)

Zhao, Yan; Gao, Wei; Xu, Bo; Li, Ying-Ai; Li, Hong-Dong; Gu, Guang-Rui; Yin, Hong

2016-10-01

The excellent physical and chemical properties of cubic boron nitride (c-BN) film make it a promising candidate for various industry applications. However, the c-BN film thickness restricts its practical applications in many cases. Thus, it is indispensable to develop an economic, simple and environment-friend way to synthesize high-quality thick, stable c-BN films. High-cubic-content BN films are prepared on silicon (100) substrates by radio frequency (RF) magnetron sputtering from an h-BN target at low substrate temperature. Adhesions of the c-BN films are greatly improved by adding hydrogen to the argon/nitrogen gas mixture, allowing the deposition of a film up to 5-μm thick. The compositions and the microstructure morphologies of the c-BN films grown at different substrate temperatures are systematically investigated with respect to the ratio of H2 gas content to total working gas. In addition, a primary mechanism for the deposition of thick c-BN film is proposed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51572105, 61504046, and 51272224), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China, the Development and Reform Commission of Jilin Province, China (Grant No. 2015Y050), and the Scientific Research Foundation for the Returned Overseas of Jilin Province, China.

Ion Beam And Plasma Jet Generated By A 3 kJ Plasma Focus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, L. K.; Ngoi, S. K.; Yap, S. L.

The plasma focus device is well known as a copious source of X-ray, neutrons, ion and electron beams. In this work, the characteristics of energetic ion beam emission in a 3 kJ Mather-type plasma focus is studied. The plasma focus system is operated at low pressure with argon as the working gas. The objective of the project is to obtain the argon ion beam and the plasma jet. The ion beam and plasma jet are used for material processing. In order to investigate the effect of the ion beam and plasma jet, crystalline silicon substrates are placed above the anode.more » Samples obtained after irradiation with the plasma focus discharge are analyzed by using the Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX).« less

Planetary Ions at Mercury: Unanswered Questions After MESSENGER

NASA Astrophysics Data System (ADS)

Raines, J. M.

2018-05-01

We will discuss the key open questions relating to planetary ions, including the behavior of recently created photoions, the near absence of Ca+ / K+ in MESSENGER ion measurements, and the role of ion sputtering in the system.

Dual-beam focused ion beam/electron microscopy processing and metrology of redeposition during ion-surface 3D interactions, from micromachining to self-organized picostructures.

PubMed

Moberlychan, Warren J

2009-06-03

Focused ion beam (FIB) tools have become a mainstay for processing and metrology of small structures. In order to expand the understanding of an ion impinging a surface (Sigmund sputtering theory) to our processing of small structures, the significance of 3D boundary conditions must be realized. We consider ion erosion for patterning/lithography, and optimize yields using the angle of incidence and chemical enhancement, but we find that the critical 3D parameters are aspect ratio and redeposition. We consider focused ion beam sputtering for micromachining small holes through membranes, but we find that the critical 3D considerations are implantation and redeposition. We consider ion beam self-assembly of nanostructures, but we find that control of the redeposition by ion and/or electron beams enables the growth of nanostructures and picostructures.

Quantitative evaluation of high-energy O- ion particle flux in a DC magnetron sputter plasma with an indium-tin-oxide target

NASA Astrophysics Data System (ADS)

Suyama, Taku; Bae, Hansin; Setaka, Kenta; Ogawa, Hayato; Fukuoka, Yushi; Suzuki, Haruka; Toyoda, Hirotaka

2017-11-01

O- ion flux from the indium tin oxide (ITO) sputter target under Ar ion bombardment is quantitatively evaluated using a calorimetry method. Using a mass spectrometer with an energy analyzer, O- energy distribution is measured with spatial dependence. Directional high-energy O- ion ejected from the target surface is observed. Using a calorimetry method, localized heat flux originated from high-energy O- ion is measured. From absolute evaluation of the heat flux from O- ion, O- particle flux in order of 1018 m-2 s-1 is evaluated at a distance of 10 cm from the target. Production yield of O- ion on the ITO target by one Ar+ ion impingement at a kinetic energy of 244 eV is estimated to be 3.3  ×  10-3 as the minimum value.

Molecular dynamics simulations of plasma-surface interactions

NASA Astrophysics Data System (ADS)

Vegh, Joseph James

Molecular dynamics (MD) simulations are carried out to examine the fundamental mechanisms of plasma-surface interactions for various systems of interest to the semiconductor industry. These include ion and radical bombardment simulations of silicon, model low-k dielectric materials, and hydrocarbon (HC) based model photoresist materials. Simulations of fluorocarbon (FC), fluorine, and argon ion etching of silicon are conducted to find conditions under which the steady state etch of Si in the presence of a FC surface layer occurs. By varying the FC/F/Ar + ratios over a range of conditions, a correlation between FC layer thickness and Si etch yield (EY) is obtained that agrees qualitatively with experimentally observed trends. Further examination of this system allows for a Si etch mechanism to be proposed. This mechanism is similar to that seen in previous Si etching simulations where FC films do not form. The FC layer is observed to fluctuate in thickness during steady state Si etch, as the result of competition between FC deposition and sputtering of relatively large (> 6 C atoms) FC clusters during Ar+ impacts. This cluster ejection process is seen in all of the systems studied, and the properties of these clusters (composition, size, kinetic energy, etc.) are examined and catalogued. Ar+ and H radical and ion bombardment of a methylated Si surface is simulated as a model of plasma etching of low-k dielectric materials. The mechanisms and product distributions observed for 300 K H radical bombardment agree well with experiment. The etch characteristics of Ar+ bombardment are examined as a function of ion energy, and the corresponding variations in surface structure at high ion fluence are characterized. Various HC polymer surfaces are studied under ion and radical bombardment to examine plasma species interactions with model photoresist materials. Simulations of 100 eV Ar+ bombardment of polystyrene (PS), poly(4-methylstyrene) (P4MS), and poly(alpha-methylstyrene) (PalphaMS) show that for all of these materials (which have similar chemical compositions: PS: (C8H 8)x, PalphaMS and P4MS: (C9H 10)x), a densely crosslinked, dehydrogenated damaged layer forms at high ion fluences that greatly reduces the sputter yield of the material. During the initial transient period of bombardment, PalphaMS shows sputter yields nearly twice as high as P4MS or PS; polymer structure can play a role during the early stages of etch. Both the initial and high fluence etch characteristics match those observed experimentally. Further, fluctuations from cell-to-cell are much higher for the PalphaMS simulations, which may correlate to the increased roughening observed experimentally for PalphaMS. Additional simulations are carried out to examine the effects of H and F radical addition during Ar+ bombardment of PS. Both radical species are shown to inhibit and/or reverse the formation of the dehydrogenated layer that forms during bombardment with Ar+ alone. Further studies examine the effect of inert ion mass through simulations of Ar +, Xe+, and He+ bombardment of PS, amorphous C, and nanoscale features on diamond surfaces. The differences in penetration depth, kinetic energy deposition, and scattering patterns are suggestive of the differing etch characteristics that are seen experimentally for these ions. A discussion of dangling bond formation during ion bombardment and longer time-scale dynamics is also offered. A brief review of currently available potential energy functions is presented. Selected results from MD simulations that utilize some of these potentials and are closely related to the work in this dissertation are also discussed. The difficulties of expanding potential energy functions vis-a-vis commonly used ab initio quantum chemical calculations are also addressed.

Rapid evaluation of ion thruster lifetime using optical emission spectroscopy

NASA Technical Reports Server (NTRS)

Rock, B. A.; Parsons, M. L.; Mantenieks, M. A.

1985-01-01

A major life-limiting phenomenon of electric thrusters is the sputter erosion of discharge chamber components. Thrusters for space propulsion are required to operate for extended periods of time, usually in excess of 10,000 hr. Lengthy and very costly life-tests in high-vacuum facilities have been required in the past to determine the erosion rates of thruster components. Alternative methods for determining erosion rates which can be performed in relatively short periods of time at considerably lower costs are studied. An attempt to relate optical emission intensity from an ion bombarded surface (screen grid) to the sputtering rate of that surface is made. The model used a kinetic steady-state (KSS) approach, balancing the rates of population and depopulation of ten low-lying excited states of the sputtered molybdenum atom (MoI) with those of the ground state to relate the spectral intensities of the various transitions of the MoI to the population densities. Once this is accomplished, the population density can be related to the sputting rate of the target. Radiative and collisional modes of excitation and decay are considered. Since actual data has not been published for MoI excitation rate and decay constants, semiempirical equations are used. The calculated sputtering rate and intensity is compared to the measured intensity and sputtering rates of the 8 and 30 cm ion thrusters.

Study on re-sputtering during CN{sub x} film deposition through spectroscopic diagnostics of plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Peipei; Yang, Xu; Li, Hui

2015-10-15

A nitrogen-carbon plasma was generated during the deposition of carbon nitride (CN{sub x}) thin films by pulsed laser ablation of a graphite target in a discharge nitrogen plasma, and the optical emission of the generated nitrogen-carbon plasma was measured for the diagnostics of the plasma and the characterization of the process of CN{sub x} film deposition. The nitrogen-carbon plasma was recognized to contain various species including nitrogen molecules and molecular ions excited in the ambient N{sub 2} gas, carbon atoms and atomic ions ablated from the graphite target and CN radicals. The temporal evolution and spatial distribution of the CNmore » emission and their dependence on the substrate bias voltage show two groups of CN radicals flying in opposite directions. One represents the CN radicals formed as the products of the reactions occurring in the nitrogen-carbon plasma, revealing the reactive deposition of CN{sub x} film due to the reactive expansion of the ablation carbon plasma in the discharge nitrogen plasma and the effective formation of gaseous CN radicals as precursors for CN{sub x} film growth. The other one represents the CN radicals re-sputtered from the growing CN{sub x} film by energetic plasma species, evidencing the re-sputtering of the growing film accompanying film growth. And, the re-sputtering presents ion-induced sputtering features.« less

Method of making an ion beam sputter-etched ventricular catheter for hydrocephalus shunt

NASA Technical Reports Server (NTRS)

Banks, B. A. (Inventor)

1984-01-01

The centricular catheter comprises a multiplicity of inlet microtubules. Each microtubule has both a large opening at its inlet end and a multiplicity of microscopic openings along its lateral surfaces. The microtubules are perforated by an ion beam sputter etch technique. The holes are etched in each microtubule by directing an ion beam through an electro formed mesh mask producing perforations having diameters ranging from about 14 microns to about 150 microns. This structure assures a reliable means for shunting cerebrospinal fluid from the cerebral ventricles to selected areas of the body.

Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersson, Joakim; Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore; Ni, Pavel

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side-on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore; Andersson, Joakim; Ni, Pavel

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

Effect of sputtering pressure on crystalline quality and residual stress of AlN films deposited at 823 K on nitrided sapphire substrates by pulsed DC reactive sputtering

NASA Astrophysics Data System (ADS)

Ohtsuka, Makoto; Takeuchi, Hiroto; Fukuyama, Hiroyuki

2016-05-01

Aluminum nitride (AlN) is a promising material for use in applications such as deep-ultraviolet light-emitting diodes (UV-LEDs) and surface acoustic wave (SAW) devices. In the present study, the effect of sputtering pressure on the surface morphology, crystalline quality, and residual stress of AlN films deposited at 823 K on nitrided a-plane sapphire substrates, which have high-crystalline-quality c-plane AlN thin layers, by pulsed DC reactive sputtering was investigated. The c-axis-oriented AlN films were homoepitaxially grown on nitrided sapphire substrates at sputtering pressures of 0.4-1.5 Pa. Surface damage of the AlN sputtered films increased with increasing sputtering pressure because of arcing (abnormal electrical discharge) during sputtering. The sputtering pressure affected the crystalline quality and residual stress of AlN sputtered films because of a change in the number and energy of Ar+ ions and Al sputtered atoms. The crystalline quality of AlN films was improved by deposition with lower sputtering pressure.

Structural and spectroscopic analysis of ex-situ annealed RF sputtered aluminium doped zinc oxide thin films

NASA Astrophysics Data System (ADS)

Otieno, Francis; Airo, Mildred; Erasmus, Rudolph M.; Billing, David G.; Quandt, Alexander; Wamwangi, Daniel

2017-08-01

Aluminium doped zinc oxide thin films are prepared by Radio Frequency magnetron sputtering in pure argon atmosphere at 100 W. The structural results reveal good film adhesion on a silicon substrate (001). The thin films were then subjected to heat treatment in a furnace under ambient air. The structural, morphological, and optical properties of the thin films as a function of deposition time and annealing temperatures have been investigated using Grazing incidence X-Ray Diffraction (GIXRD), Atomic Force Microscopy, and Scanning Electronic Microscopy. The photoluminescence properties of the annealed films showed significant changes in the optical properties attributed to mid gap defects. Annealing increases the crystallite size and the roughness of the film. The crystallinity of the films also improved as evident from the Raman and XRD studies.

The influence of pressure and gas flow on size and morphology of titanium oxide nanoparticles synthesized by hollow cathode sputtering

NASA Astrophysics Data System (ADS)

Gunnarsson, Rickard; Pilch, Iris; Boyd, Robert D.; Brenning, Nils; Helmersson, Ulf

2016-07-01

Titanium oxide nanoparticles have been synthesized via sputtering of a hollow cathode in an argon atmosphere. The influence of pressure and gas flow has been studied. Changing the pressure affects the nanoparticle size, increasing approximately proportional to the pressure squared. The influence of gas flow is dependent on the pressure. In the low pressure regime (107 ≤ p ≤ 143 Pa), the nanoparticle size decreases with increasing gas flow; however, at high pressure (p = 215 Pa), the trend is reversed. For low pressures and high gas flows, it was necessary to add oxygen for the particles to nucleate. There is also a morphological transition of the nanoparticle shape that is dependent on the pressure. Shapes such as faceted, cubic, and cauliflower can be obtained.

Enhanced c-axis orientation of aluminum nitride thin films by plasma-based pre-conditioning of sapphire substrates for SAW applications

NASA Astrophysics Data System (ADS)

Gillinger, M.; Shaposhnikov, K.; Knobloch, T.; Stöger-Pollach, M.; Artner, W.; Hradil, K.; Schneider, M.; Kaltenbacher, M.; Schmid, U.

2018-03-01

Aluminum nitride (AlN) on sapphire has been investigated with two different pretreatments prior to sputter deposition of the AlN layer to improve the orientation and homogeneity of the thin film. An inverse sputter etching of the substrate in argon atmosphere results in an improvement of the uniformity of the alignment of the AlN grains and hence, in enhanced electro-mechanical AlN film properties. This effect is demonstrated in the raw measurements of SAW test devices. Additionally, the impulse response of several devices shows that a poor AlN thin film layer quality leads to a higher signal damping during the transduction of energy in the inter-digital transducers. As a result, the triple-transit signal cannot be detected at the receiver.

Simulations of Proton Implantation in Silicon Carbide (SiC)

DTIC Science & Technology

2016-03-31

ions in matter (SRIM); transport of ions in matter (TRIM); ion energy; implant depth; defect generation; vacancy; backscattered ions; sputtering...are computer simulations based on transport of ions in matter (TRIM), and stopping and range of ions in matter (SRIM). TRIM is a Monte Carlo

Comparison in the analytical performance between krypton and argon glow discharge plasmas as the excitation source for atomic emission spectrometry.

PubMed

Wagatsuma, Kazuaki

2009-04-01

The emission characteristics of ionic lines of nickel, cobalt, and vanadium were investigated when argon or krypton was employed as the plasma gas in glow discharge optical emission spectrometry. A dc Grimm-style lamp was employed as the excitation source. Detection limits of the ionic lines in each iron-matrix alloy sample were compared between the krypton and the argon plasmas. Particular intense ionic lines were observed in the emission spectra as a function of the discharge gas (krypton or argon), such as the Co II 258.033 nm for krypton and the Co II 231.707 nm for argon. The explanation for this is that collisions with the plasma gases dominantly populate particular excited levels of cobalt ion, which can receive the internal energy from each gas ion selectively, for example, the 3d(7)4p (3)G(5) (6.0201 eV) for krypton and the 3d(7)4p (3)G(4) (8.0779 eV) for argon. In the determination of nickel as well as cobalt in iron-matrix samples, more sensitive ionic lines could be found in the krypton plasma rather than the argon plasma. Detection limits in the krypton plasma were 0.0039 mass% Ni for the Ni II 230.299-nm line and 0.002 mass% Co for the Co II 258.033-nm line. However, in the determination of vanadium, the argon plasma had better analytical performance, giving a detection limit of 0.0023 mass% V for the V II 309.310-nm line.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murzin, I.H.; Tompa, G.S.; Wei, J.

The authors report the results of using sputtering and negative carbon ion sources to prepare thin films of carbon nitride. In this work, they compare the structural, tribological, and optical properties of the carbon nitride films that were prepared by two different ion assisted techniques. In the first approach they used a magnetron gun to sputter deposit carbon in a nitrogen atmosphere. The second method utilized a beam of negatively charged carbon ions of 1 to 5 {micro}A/cm{sup 2} current density impinging the substrate simultaneously with a positive nitrogen ion beam produced by a Kaufman source. They were able tomore » synthesize microscopically smooth coatings with the carbon to nitrogen ratio of 1:0.47. These films possess wear rates lower than 5 {times} 10{sup {minus}7} mm{sup 3}/Nm and friction coefficients in the range of 0.16 to 0.6. Raman spectroscopy revealed that the magnetron sputtered films are more structurally disordered than those formed with the negative carbon ion gun. FTIR showed the presence of the C{triple_bond}N stretching mode in both types of films. Finally, spectroscopic ellipsometry produced films with dielectric constants as low as 2.3 in the photon energy range from 1.2 to 5 eV.« less

Charged particle modification of ices in the Saturnian and Jovian systems

NASA Technical Reports Server (NTRS)

Johnson, R. E.; Barton, L. A.; Boring, J. W.; Jesser, W. A.; Brown, W. L.

1985-01-01

The modification by ion bombardment of the surfaces of icy objects in the Saturnian and Jovian systems is discussed. Chemical changes in ices are induced by breaking of bonds and by implantation of incident ions. Long-term irradiation by fast ions produces physical changes such as increasing the surface reflectivity and ability to scatter light. On large satellites, molecules which are ejected by ion bombardment are redistributed across the surfaces of large satellites. For small satellites and ring particles bombarded by ions, such as those of Saturn, most or all of the sputtered material is lost to space, forming a neutral torus in the locale of the satellite orbits and rings and supplying ions to the magnetosphere. Noting the existence of such a torus, the sputter erosion and possible stabilization of the E-ring of Saturn is discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuomo, J.J.; Rossnagel, S.M.; Kaufman, H.R.

The work presented in this book deals with ion beam processing for basic sputter etching of samples, for sputter deposition of thin films, for the synthesis of material in thin form, and for the modification of the properties of thin films. The ion energy range covered is from a few tens of eV to about 10,000 eV, with primary interest in the range of about 20 to 1-2 keV, where implantation of the incident ion is a minor effect. Of the types of ion sources and devices available, this book examines principally broad beam ion sources, characterized by high fluxesmore » and large work areas. These sources include the ECR ion source, the Kaufman-type single- and multiple-grid sources, gridless sources such as the Hall effect or closed-drift source, and hydrid sources such as the ionized cluster beam system.« less

Plasma & reactive ion etching to prepare ohmic contacts

DOEpatents

Gessert, Timothy A.

2002-01-01

A method of making a low-resistance electrical contact between a metal and a layer of p-type CdTe surface by plasma etching and reactive ion etching comprising: a) placing a CdS/CdTe layer into a chamber and evacuating said chamber; b) backfilling the chamber with Argon or a reactive gas to a pressure sufficient for plasma ignition; and c) generating plasma ignition by energizing a cathode which is connected to a power supply to enable the plasma to interact argon ions alone or in the presence of a radio-frequency DC self-bias voltage with the p-CdTe surface.

Preparation of a primary argon beam for the CERN fixed target physics.

PubMed

Küchler, D; O'Neil, M; Scrivens, R; Thomae, R

2014-02-01

The fixed target experiment NA61 in the North Area of the Super Proton Synchrotron is studying phase transitions in strongly interacting matter. Up to now they used the primary beams available from the CERN accelerator complex (protons and lead ions) or fragmented beams created from the primary lead ion beam. To explore a wider range of energies and densities a request was made to provide primary argon and xenon beams. This paper describes the results of the setting up and 10 week test run of the Ar(11+) beam from the 14.5 GHz ECR ion source and the linear accelerator (Linac3) at CERN.

Cassini CAPS Identification of Pickup Ion Compositions at Rhea

NASA Astrophysics Data System (ADS)

Desai, R. T.; Taylor, S. A.; Regoli, L. H.; Coates, A. J.; Nordheim, T. A.; Cordiner, M. A.; Teolis, B. D.; Thomsen, M. F.; Johnson, R. E.; Jones, G. H.; Cowee, M. M.; Waite, J. H.

2018-02-01

Saturn's largest icy moon, Rhea, hosts a tenuous surface-sputtered exosphere composed primarily of molecular oxygen and carbon dioxide. In this Letter, we examine Cassini Plasma Spectrometer velocity space distributions near Rhea and confirm that Cassini detected nongyrotropic fluxes of outflowing CO2+ during both the R1 and R1.5 encounters. Accounting for this nongyrotropy, we show that these possess comparable along-track densities of ˜2 × 10-3 cm-3. Negatively charged pickup ions, also detected during R1, are surprisingly shown as consistent with mass 26 ± 3 u which we suggest are carbon-based compounds, such as CN-, C2H-, C2-, or HCO-, sputtered from carbonaceous material on the moon's surface. The negative ions are calculated to possess along-track densities of ˜5 × 10-4 cm-3 and are suggested to derive from exogenic compounds, a finding consistent with the existence of Rhea's dynamic CO2 exosphere and surprisingly low O2 sputtering yields. These pickup ions provide important context for understanding the exospheric and surface ice composition of Rhea and of other icy moons which exhibit similar characteristics.

High Useful Yield and Isotopic Analysis of Uranium by Resonance Ionization Mass Spectrometry

DOE PAGES

Savina, Michael R.; Isselhardt, Brett H.; Kucher, Andrew; ...

2017-05-09

Useful yields from resonance ionization mass spectrometry can be extremely high compared to other mass spectrometry techniques, but uranium analysis shows strong matrix effects arising from the tendency of uranium to form strongly bound oxide molecules that do not dissociate appreciably on energetic ion bombardment. Here, we demonstrate a useful yield of 24% for metallic uranium. Modeling the laser ionization and ion transmission processes shows that the high useful yield is attributable to a high ion fraction achieved by resonance ionization. We quantify the reduction of uranium oxide surface layers by Ar + and Ga + sputtering. The useful yieldmore » for uranium atoms from a uranium dioxide matrix is 0.4% and rises to 2% when the surface is in sputter equilibrium with the ion beam. The lower useful yield from the oxide is almost entirely due to uranium oxide molecules reducing the neutral atom content of the sputtered flux. We also demonstrate rapid isotopic analysis of solid uranium oxide at a precision of <0.5% relative standard deviation using relatively broadband lasers to mitigate spectroscopic fractionation.« less

High Useful Yield and Isotopic Analysis of Uranium by Resonance Ionization Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savina, Michael R.; Isselhardt, Brett H.; Kucher, Andrew

Useful yields from resonance ionization mass spectrometry can be extremely high compared to other mass spectrometry techniques, but uranium analysis shows strong matrix effects arising from the tendency of uranium to form strongly bound oxide molecules that do not dissociate appreciably on energetic ion bombardment. Here, we demonstrate a useful yield of 24% for metallic uranium. Modeling the laser ionization and ion transmission processes shows that the high useful yield is attributable to a high ion fraction achieved by resonance ionization. We quantify the reduction of uranium oxide surface layers by Ar + and Ga + sputtering. The useful yieldmore » for uranium atoms from a uranium dioxide matrix is 0.4% and rises to 2% when the surface is in sputter equilibrium with the ion beam. The lower useful yield from the oxide is almost entirely due to uranium oxide molecules reducing the neutral atom content of the sputtered flux. We also demonstrate rapid isotopic analysis of solid uranium oxide at a precision of <0.5% relative standard deviation using relatively broadband lasers to mitigate spectroscopic fractionation.« less

Conformal growth of Mo/Si multilayers on grating substrates using collimated ion beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voronov, D. L.; Gawlitza, Peter; Cambie, Rossana

2012-05-07

Deposition of multilayers on saw-tooth substrates is a key step in the fabrication of multilayer blazed gratings (MBG) for extreme ultraviolet and soft x-rays. Growth of the multilayers can be perturbed by shadowing effects caused by the highly corrugated surface of the substrates, which results in distortion of the multilayer stack structure and degradation of performance of MBGs. In this study, to minimize the shadowing effects, we used an ion-beamsputtering machine with a highly collimated atomic flux to deposit Mo/Si multilayers on saw-tooth substrates. The sputtering conditions were optimized by finding a balance between smoothening and roughening processes in ordermore » to minimize degradation of the groove profile in the course of deposition and at the same time to keep the interfaces of a multilayer stack smooth enough for high efficiency. An optimal value of energy of 200 eV for sputtering Kr + ions was found by deposition of test multilayers on flat substrates at a range of ion energies. Two saw-tooth substrates were deposited at energies of 200 eV and 700 eV for the sputtering ions. It was found that reduction of the ion energy improved the blazing performance of the MBG and resulted in a 40% gain in the diffraction efficiency due to better replication of the groove profile by the multilayer. As a result of the optimization performed, an absolute diffraction efficiency of 28.8% was achieved for the 2nd blaze order of the MBG with a groove density of 7350 lines/mm at a wavelength of 13.5 nm. Lastly, details of the growth behavior of the multilayers on flat and saw-tooth substrates are discussed in terms of the linear continuous model of film growth.« less

Sputtering in mercury ion thrusters

NASA Technical Reports Server (NTRS)

Mantenieks, M. A.; Rawlin, V. K.

1979-01-01

A model, which assumes that chemisorption is the dominant mechanism, is applied to the sputtering rate measurements of the screen grid of a 30 cm thruster in the presence of nitrogen. The model utilizes inputs from a variety of experimental and analytical sources. The model of environmental effects on sputtering was applied to thruster conditions of low discharge voltage and a discussion of the comparison of theory and experiment is presented.

Post-Test Analysis of the Deep Space One Spare Flight Thruster Ion Optics

NASA Technical Reports Server (NTRS)

Anderson, John R.; Sengupta, Anita; Brophy, John R.

2004-01-01

The Deep Space 1 (DSl) spare flight thruster (FT2) was operated for 30,352 hours during the extended life test (ELT). The test was performed to validate the service life of the thruster, study known and identify unknown life limiting modes. Several of the known life limiting modes involve the ion optics system. These include loss of structural integrity for either the screen grid or accelerator grid due to sputter erosion from energetic ions striking the grid, sputter erosion enlargement of the accelerator grid apertures to the point where the accelerator grid power supply can no longer prevent electron backstreaming, unclearable shorting between the grids causes by flakes of sputtered material, and rouge hole formation due to flakes of material defocusing the ion beam. Grid gap decrease, which increases the probability of electron backstreaming and of arcing between the grids, was identified as an additional life limiting mechanism after the test. A combination of accelerator grid aperture enlargement and grid gap decrease resulted in the inability to prevent electron backstreaming at full power at 26,000 hours of the ELT. Through pits had eroded through the accelerator grid webbing and grooves had penetrated through 45% of the grid thickness in the center of the grid. The upstream surface of the screen grid eroded in a chamfered pattern around the holes in the central portion of the grid. Sputter deposited material, from the accelerator grid, adhered to the downstream surface of the screen grid and did not spall to form flakes. Although a small amount of sputter deposited material protruded into the screen grid apertures, no rouge holes were found after the ELT.

Sputtering and detection of large organic molecules from Europa

NASA Astrophysics Data System (ADS)

Johnson, R. E.; Sundqvist, B. U. R.

2018-07-01

Mass spectroscopy of bio-molecules by heavy ion induced sputtering, which became a practical laboratory procedure, was also suggested as a potential tool for spacecraft studies of targets of interest in astrobiology. With the planning of new missions to Europa, there is renewed interest in the possibility of detecting organic molecules that might have originated in its subsurface ocean and can be sputtered from its surface often intact by impacting energetic heavy ions trapped in Jupiter's magnetosphere. Here we review the laboratory data and modeling bearing on this issue. We then give estimates of the ejection into the gas-phase of trace organic species embedded in an ice matrix on Europa's surface and their possible detection during a flyby mission.

The production and sputtering of S2 by keV ion bombardment

NASA Technical Reports Server (NTRS)

Boring, J. W.; Chrisey, D. B.; Oshaughnessy, D. J.; Phipps, J. A.; Zhao, N.

1986-01-01

The ion bombardment of S-containing molecules in comets is simulated experimentally. Mass-analyzed 30-keV beams of Ar(+) and He(+) are directed at solid S, H2S, and CS2 targets at temperatures 15 K, and the neutral molecular species produced are ionized and analyzed using a quadrupole mass spectrometer. The dominant species detected are S1 and S2 for the S target, H2S and S2 for the H2S target, and S, CS, S2, and CS2 for the CS2 target. In the latter case, it is found that after about 10 to the 14th He(+) ions/sq cm have struck the target, further sputtering is prevented by formation of a dark brown deposit which is stable at room temperature; the residue forms more slowly when Ar(+) ions are used. These results, indicating relatively efficient S2 production by ion bombardment, are applied to theoretical models of S2 production and/or ejection by solar-wind, solar-flare, or cosmic-ray ions striking comets. It is found that direct solar-wind production of S2 by sputtering is unlikely at realistic bombardment rates, but that H2S-S2 conversion by energetic ions could be significant, with less stringent ice-temperature and irradiation-flux constraints than in the case of S2 production by photons.

Numerical study on characteristics of radio-frequency discharge at atmospheric pressure in argon with small admixtures of oxygen

NASA Astrophysics Data System (ADS)

Wang, Yinan; Liu, Yue

2017-07-01

In this paper, a 1D fluid model is developed to study the characteristics of a discharge in argon with small admixtures of oxygen at atmospheric pressure. This model consists of a series of equations, including continuity equations for electrons, positive ions, negative ions and neutral particles, the energy equation, and the Poisson equation for electric potential. Special attention has been paid to the electron energy dissipation and the mechanisms of electron heating, while the admixture of oxygen is in the range of 0.1%-0.6%. It is found that when the oxygen-to-argon ratio grows, the discharge is obviously divided into three stages: electron growth, electron reduction and the electron remaining unchanged. Furthermore, the cycle-averaged electric field, electron temperature, electron Ohmic heating, electron collisionless heating, electron energy dissipation and the net electron production are also studied in detail, and when the oxygen-to-argon ratio is relatively larger (R = 0.6%), double value peaks of electron Ohmic heating appear in the sheath. According to the results of the numerical simulation, various oxygen-to-argon ratios result in different amounts of electron energy dissipation and electron heating.

Effects of Radiation on Oxide Materials.

DTIC Science & Technology

1981-11-01

argon sputtering. The results show that this technique is quite successful and makes it possible to profile implanted Na that fits the theoretical ...the finite escape depth of the photoionized electrons. Thicker (100 R) oxides were used for depth-profiling XPS measurements. 6.3.2 Results--30-R Films... Scofield , J. Electron Spectrosc. 8, 129 (1976). 63 SOFT SILICON DIOXIOE ON SILICON (WET GROWN) 12 . 0 1 10 o - AUGER z 0 ,- C- IS" SI - 2S Z N-I i sI-P 2 0

Reduction Expansion Synthesis of Chromium and Nickel Metal Coatings

DTIC Science & Technology

2017-06-01

to a supersonic speed [24]–[25]. To prevent undesired combustion, an inert gas is required for because the gas temperature increases to 100–500°C in...take place. The metal is added by mechanical means only. In the sputtering process, an inert gas (e.g., argon) is supplied to a vacuum chamber with...technique that uses metal powder and compressed gas to feed the powder to a converging-diverging nozzle [24], as shown in Figure 5. The converging

Heavy ion beam-ionosphere interactions - Electron acceleration

NASA Technical Reports Server (NTRS)

Kaufmann, R. L.; Arnoldy, R. L.; Moore, T. E.; Kintner, P. M.; Cahill, L. J., Jr.

1985-01-01

Moore et al. (1982) described a number of unexpected effects which were observed during the first Argon Release Controlled Study (ARCS 1, or rocket flight 29:014). The present paper provides a description of detailed analyses of the interaction of the argon beam with the ionosphere. An important feature of the considered test was that all detectors and the Ar(+) gun remained attached to the rocket throughout the flight. It is pointed out that the most dramatic effect of ion gun operation on ARCS 1 involved large changes in the fluxes of electrons with energies below about 600 eV. The observations are discussed, taking into account the distribution functions, azimuth dependence, and electron and ion trajectories. Attention is given to the perpendicular ion beam, the parallel ion beam, the acceleration of downgoing and upgoing electrons, and aspects of wave generation.

Penning discharge ion source with self-cleaning aperture

DOEpatents

Gavin, B.F.; MacGill, R.A.; Thatcher, R.K.

1980-11-10

An ion source of the Penning discharge type having a self-cleaning aperture is provided by a second dynode with an exit aperture in a position opposite a first dynode, from which the ions are sputtered, two opposing cathodes, each with an anode for accelerating electrons emitted from the cathodes into a cylindrical space defined by the first and second dynode. A support gas maintained in this space is ionized by the electrons. While the cathodes are supplied with a negative pulse to emit electrons, the first dynode is supplied with a negative pulse (e.g., -300 V) to attract atoms of the ionized gas (plasma). At the same time, the second dynode may also be supplied with a small voltage that is negative with respect to the plasma (e.g., -5 V) for tuning the position of the plasma miniscus for optimum extraction geometry. When the negative pulse to the first dynode is terminated, the second dynode is driven strongly negative (e.g., -600 V) thereby allowing heavy sputtering to take place for a short period to remove virtually all of the atoms deposited on the second dynode from material sputtered off the first dynode. An extractor immediately outside the exit aperture of the second dynode is maintained at ground potential while the anode, dynode, and cathode reference voltage is driven strongly positive (about +20 kV to +30 kV) so that ions accelerated through the aperture will be at ground potential. Material from the first dynode deposited on the second dynode will be sputtered, in time, to add to the ion beam.

JPRS Report, Science & Technology, Japan, SOR Technology Update

DTIC Science & Technology

1990-12-18

GUN Electron gun c3 GV Gate valve R- ± HL Helmholtz coil IG Ion vacuum gauge IP Ion pump KFC Klystron focusing coil KLY Klystron PB Pre-buncher Q...Therefore, we started studying the manufacture of this kind of film. Recently, such films have been placed on the market as test samples by some foreign... Mixing of sputtered particles from the two targets can also be prevented by making the structure of the bulkhead in the sputtering chamber most

Investigation on the effect of nonlinear processes on similarity law in high-pressure argon discharges

NASA Astrophysics Data System (ADS)

Fu, Yangyang; Parsey, Guy M.; Verboncoeur, John P.; Christlieb, Andrew J.

2017-11-01

In this paper, the effect of nonlinear processes (such as three-body collisions and stepwise ionizations) on the similarity law in high-pressure argon discharges has been studied by the use of the Kinetic Global Model framework. In the discharge model, the ground state argon atoms (Ar), electrons (e), atom ions (Ar+), molecular ions (Ar2+), and fourteen argon excited levels Ar*(4s and 4p) are considered. The steady-state electron and ion densities are obtained with nonlinear processes included and excluded in the designed models, respectively. It is found that in similar gas gaps, keeping the product of gas pressure and linear dimension unchanged, with the nonlinear processes included, the normalized density relations deviate from the similarity relations gradually as the scale-up factor decreases. Without the nonlinear processes, the parameter relations are in good agreement with the similarity law predictions. Furthermore, the pressure and the dimension effects are also investigated separately with and without the nonlinear processes. It is shown that the gas pressure effect on the results is less obvious than the dimension effect. Without the nonlinear processes, the pressure and the dimension effects could be estimated from one to the other based on the similarity relations.

Chemical sputtering by H{sub 2}{sup +} and H{sub 3}{sup +} ions during silicon deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landheer, K., E-mail: c.landheer@uu.nl; Poulios, I.; Rath, J. K.

2016-08-07

We investigated chemical sputtering of silicon films by H{sub y}{sup +} ions (with y being 2 and 3) in an asymmetric VHF Plasma Enhanced Chemical Vapor Deposition (PECVD) discharge in detail. In experiments with discharges created with pure H{sub 2} inlet flows, we observed that more Si was etched from the powered than from the grounded electrode, and this resulted in a net deposition on the grounded electrode. With experimental input data from a power density series of discharges with pure H{sub 2} inlet flows, we were able to model this process with a chemical sputtering mechanism. The obtained chemicalmore » sputtering yields were (0.3–0.4) ± 0.1 Si atom per bombarding H{sub y}{sup +} ion at the grounded electrode and at the powered electrode the yield ranged from (0.4 to 0.65) ± 0.1. Subsequently, we investigated the role of chemical sputtering during PECVD deposition with a series of silane fractions S{sub F} (S{sub F}(%) = [SiH{sub 4}]/[H{sub 2}]*100) ranging from S{sub F} = 0% to 20%. We experimentally observed that the SiH{sub y}{sup +} flux is not proportional to S{sub F} but decreasing from S{sub F} = 3.4% to 20%. This counterintuitive SiH{sub y}{sup +} flux trend was partly explained by an increasing chemical sputtering rate with decreasing S{sub F} and partly by the reaction between H{sub 3}{sup +} and SiH{sub 4} that forms SiH{sub 3}{sup +}.« less

Mutagenic effects of heavy ion radiation in plants

NASA Astrophysics Data System (ADS)

Mei, M.; Deng, H.; Lu, Y.; Zhuang, C.; Liu, Z.; Qiu, Q.; Qiu, Y.; Yang, T. C.

1994-10-01

Genetic and developmental effects of heavy ions in maize and rice were investigated. Heavy particles with various charges and energies were accelerated at the BEVALAC. The frequency of occurence of white-yellow stripes on leaves of plants developed from irradiated maize seeds increased linearly with dose, and high-LET heavy charged particles, e.g., neon, argon, and iron, were 2-12 times as effective as gamma rays in inducing this type of mutation. The effectiveness of high-LET heavy ion in (1) inhibiting rice seedling growth, (2) reducing plant fertility, (3) inducing chromosome aberration and micronuclei in root tip cells and pollen mother cells of the first generation plants developed from exposed seeds, and (4) inducing mutation in the second generation, were greater than that of low-LET gamma rays. All effects observed were dose-dependent; however, there appeared to be an optimal range of doses for inducing certain types of mutation, for example, for argon ions (400 MeV/u) at 90-100 Gy, several valuable mutant lines with favorable characters, such as semidwarf, early maturity and high yield ability, were obtained. Experimental results suggest that the potential application of heavy ions in crop improvement is promising. RFLP analysis of two semidwarf mutants induced by argon particles revealed that large DNA alterations might be involved in these mutants.

Sputter erosion and deposition in the discharge chamber of a small mercury ion thruster

NASA Technical Reports Server (NTRS)

Power, J. L.

1973-01-01

A 5 cm diameter mercury ion thruster similar to one tested for 9715 hours was operated approximately 400 hrs each at discharge voltages of 36.6, 39.6, and 42.6 V, with corresponding discharge propellant utilizations of 58, 68, and 70 percent. The observed sputter erosion rates of the internal thruster parts and the anode weight gain rate all rose rapidly with discharge voltage and were roughly in the ratio of 1:3:5 for the three voltages. The combined weight loss of the internal thruster parts nearly balanced the anode weight gain. Hg(+2) ion apparently caused most of the observed erosion.

Device for providing high-intensity ion or electron beam

DOEpatents

McClanahan, Edwin D.; Moss, Ronald W.

1977-01-01

A thin film of a low-thermionic-work-function material is maintained on the cathode of a device for producing a high-current, low-pressure gas discharge by means of sputter deposition from an auxiliary electrode. The auxiliary electrode includes a surface with a low-work-function material, such as thorium, uranium, plutonium or one of the rare earth elements, facing the cathode but at a disposition and electrical potential so as to extract ions from the gas discharge and sputter the low-work-function material onto the cathode. By continuously replenishing the cathode film, high thermionic emissions and ion plasmas can be realized and maintained over extended operating periods.

Ion energies in high power impulse magnetron sputtering with and without localized ionization zones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yuchen; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720; Tanaka, Koichi

2015-03-23

High speed imaging of high power impulse magnetron sputtering discharges has revealed that ionization is localized in moving ionization zones but localization disappears at high currents for high yield targets. This offers an opportunity to study the effect ionization zones have on ion energies. We measure that ions have generally higher energies when ionization zones are present, supporting the concept that these zones are associated with moving potential humps. We propose that the disappearance of ionization zones is caused by an increased supply of atoms from the target which cools electrons and reduces depletion of atoms to be ionized.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu Shioumin; Kruijs, Robbert van de; Zoethout, Erwin

Ion sputtering yields for Ru, Mo, and Si under Ar{sup +} ion bombardment in the near-threshold energy range have been studied using an in situ weight-loss method with a Kaufman ion source, Faraday cup, and quartz crystal microbalance. The results are compared to theoretical models. The accuracy of the in situ weight-loss method was verified by thickness-decrease measurements using grazing incidence x-ray reflectometry, and results from both methods are in good agreement. These results provide accurate data sets for theoretical modeling in the near-threshold sputter regime and are of relevance for (optical) surfaces exposed to plasmas, as, for instance, inmore » extreme ultraviolet photolithography.« less

Improved Multiple-Species Cyclotron Ion Source

NASA Technical Reports Server (NTRS)

Soli, George A.; Nichols, Donald K.

1990-01-01

Use of pure isotope 86Kr instead of natural krypton in multiple-species ion source enables source to produce krypton ions separated from argon ions by tuning cylcotron with which source used. Addition of capability to produce and separate krypton ions at kinetic energies of 150 to 400 MeV necessary for simulation of worst-case ions occurring in outer space.

Detection of singly ionized energetic lunar pick-up ions upstream of earth's bow shock

NASA Technical Reports Server (NTRS)

Hilchenbach, M.; Hovestadt, D.; Klecker, B.; Moebius, E.

1992-01-01

Singly ionized suprathermal ions upstream of the earth's bow shock have been detected by using the time-of-flight spectrometer SULEICA on the AMPTE/IRM satellite. The data were collected between August and December 1985. The flux of the ions in the mass range between 23 and 37 amu is highly anisotropic towards the earth. The ions are observed with a period of about 29 days around new moon (+/- 3 days). The correlation of the energy of the ions with the solar wind speed and the interplanetary magnetic field orientation indicates the relation to the pick-up process. We conclude that the source of these pick-up ions is the moon. We argue that due to the impinging solar wind, atoms are sputtered off the lunar surface, ionized in the sputtering process or by ensuing photoionization and picked up by the solar wind.

Secondary ion emission from Ti, V, Cu, Ag and Au surfaces under KeV Cs + irradiation

NASA Astrophysics Data System (ADS)

van der Heide, P. A. W.

2005-02-01

Low energy mono-atomic singly charged secondary ion emissions from Ti, V, Cu, Ag and Au substrates during the initial stages of sputtering with Cs + primary ions have been studied. With the exception of the Ag - secondary ions, all exhibited exponential like correlations with the Cs induced work function changes. This, along with the lack of variations in the valence band structure around the Fermi edge, is consistent with resonance charge transfer to/from states located at the Fermi edge. The insensitivity of Ag - to work function appears to stem from the dominance of a separate ion formation process, namely charge transfer into vacant 4d states in the sputtered population, which themselves appear to be produced through collective oscillations. A similar excitation-mediated process involving different levels also appears to be active in the formation of other negatively charged transition metal ions, albeit to a much lesser degree.