Teses / dissertações: "Ion bombardment"

1

McLaren, M. G. "Ion bombardment induced deposition of tungsten". Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308526.

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2

Samartsev, Andrey V. "Sputtering of Indium under polyatomic ion bombardment". [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=976510278.

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3

Whitlow, Harry James. "Ion-materials interactions and their application". Thesis, University of Bath, 1998. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285272.

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4

Kucheyev, Sergei Olegovich. "Ion-beam processes in group-III nitrides". View thesis entry in Australian Digital Theses Program, 2002. http://thesis.anu.edu.au/public/adt-ANU20030211.170915/index.html.

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5

Locklear, Jay Edward. "Secondary ion emission under keV carbon cluster bombardment". Diss., Texas A&M University, 2006. http://hdl.handle.net/1969.1/4273.

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Secondary ion mass spectrometry (SIMS) is a surface analysis technique capable of providing isotopic and molecular information. SIMS uses keV projectiles to impinge upon a sample resulting in secondary ion emission from nanometric dimensions. It is well documented that secondary ion emission is enhanced using cluster projectiles compared to atomic projectiles. Previous studies of enhanced secondary ion yields with cluster projectiles have led to the present study dealing with the scope of C60 as a projectile for SIMS. The secondary ion yields (i.e., the number of secondary ions detected per projectile impact) from impacts of 10-26 keV C24H12+, C60+, gramicidin S+ and C60F40+ projectiles were examined to compare the effectiveness of the projectiles. The [M-H]- secondary ion yields from several organic samples varied inversely with the molecular weight. Multiple ion emission decreases monotonically as a function of the number of secondary ions emitted per impact and varies with impact energy such that higher energies produce more multiple ion emission. The emission of CN- from biological samples as a function of carbon-based projectile characteristics was examined to explore the possibility of using CN- as a molecular identifier. CN- emission was found to be the product of both direct and recombination/rearrangement emission. Re-emitted projectile atoms in the form F- were found under C60F40+ bombardment. Two forms of re-emitted F- were found: One form in which F atoms retained a portion of the initial kinetic energy, and a second in which the F atoms deposited most of the initial kinetic energy into the surface before being ejected. The [M-H]- secondary ion yield of gramicidin S was increased ~ 15 times by embedding the analyte in a matrix of sinapic acid. These results show the optimum carbon based projectile for a given sample is dependent upon the signal to be monitored from the surface. The results also show CN- has potential as a molecular identifier. Additionally, the detection of re-emitted F- confirms prior predictions of re-emitted projectile atoms.

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6

Zeroual, Boudjemaa. "Ion bombardment induced damage and annealing in Si". Thesis, University of Salford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258251.

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7

Yin, Jian. "Mechanism studies of fast atom bombardment mass spectrometry". Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/25987.

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8

Alzaim, Safa. "Studies of nanostructure fabrication and morphology development during ion bombardment as a function of bombardment angle". Thesis, Boston University, 2008. https://hdl.handle.net/2144/27575.

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Thesis (B.A.)--Boston University. University Professors Program Senior theses.
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
In order to investigate the behavior of nanostructures during the widely-used process of ion bombardment, the mechanisms of ion bombardment on nanostructures were studied. Nanostructures were fabricated into silicon wafers. The fabrication process involved writing with scanning electron microscopy (SEM) a pattern in poly(methyl methacrylate) (PMMA) polymer resist layered over the silicon, removing the written PMMA in development with methyl isobutyl ketone (MIBK) and isopropanol, layering the wafer with chromium in thermal evaporation, removing the PMMA and its chromium covering with acetone, etching the chromium of the pattern with reactive ion etching, and finally removing the chromium with an etching reagent. The final structures were ion bombarded under 3*10^-3 torr for three hours at 1000 V and 40mA, with Argon; the bombarding was performed at degree angles of 60 and normal incidence. A sample without the fabrication of structures is bombarded at normal incidence as well. One sample with fabricated structures is studied without bombardment as an experimental control. The results were erosion of the bombarded structures, cones and dots.
2031-01-02

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9

Zabeida, Oleg Vasilyevich. "Study of ion bombardment characteristics in high frequency plasmas". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ53549.pdf.

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10

SAXE, STEVEN GARY. "ION-INDUCED PROCESSES IN OPTICAL COATINGS (BOMBARDMENT, THIN FILMS)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188076.

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Nearly all the deficiencies of conventional vacuum evaporated coatings trace to a single physical property of condensed films: low packing density. One way to increase packing density is to bombard the growing film with ions during deposition, called ion-assisted deposition (IAD). The beginning chapters of this dissertation analyze IAD as a perturbation of the conventional vacuum evaporation process. The experimental chapters begin with an examination of the effect on moisture penetration behavior of oxygen-ion bombarding completed optical filters. Moisture adsorption and desorption is retarded after bombardment in filters composed of titania and silica, but not in those of zirconia and silica. Bombardment evidently induces a crystalline-to-amorphous transition in titania, causing the surface to swell and occluding the pores. The transition in zirconia is the reverse, and no impediment to moisture appears. Argon-ion-assisted magnesium fluoride (MgF₂) can show ultraviolet (UV) absorption. The primary mechanism is probably the formation of F-centers (single fluorine-ion vacancies), although an unsaturated oxygen bond may also be responsible. Absorption can be removed by baking and often by irradiation with UV. After baking, fluorine is lost and replaced by oxygen. Absorption-free MgF₂ films can be deposited by minimizing the substrate temperature and bombardment flux. Ion-assisted films contain up to 2% argon and up to 170 parts-per-million of tungsten from the ion gun filaments. They show a slightly higher refractive index, are much less porous, and are much more resistant to damage by abrasion and exposure to fluorine gas. Ion-assisted aluminum oxide (alumina, Al₂O₃) films show a small increase in UV absorption after argon-ion bombardment; however, a mixture of argon and oxygen ions avoids the problem. Excess oxygen is often incorporated into alumina films, and depresses both the mass density and the refractive index. IAD increases refractive index and decreases porosity. Ion-assisted alumina films are somewhat more stable in humid environments. Ion-assisted deposition has been shown by this study to cause substantial improvements in many of the physical and some of the optical and chemical properties of evaporated magnesium fluoride and aluminum oxide films.

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11

Lamouri, Abbas. "Low-energy sputtering of Teflon by oxygen ion bombardment". Case Western Reserve University School of Graduate Studies / OhioLINK, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055777824.

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12

Arnold, John Christopher 1964. "Modification of Schottky diode performance due to ion bombardment". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277047.

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An experimental and theoretical analysis of the effects of ion bombardment on Schottky diodes is presented. The experimentally observed shifts in diode performance are compared to the conditions of ion exposure. These experiments show that Schottky diodes exposed to ion beams show decreases in effective barrier heights and ideality factors, as well as increased incidence of premature reverse breakdown. The change in barrier height is found to be proportional to the energy of the individual ions and the total number of ions delivered to the surface. A numerical simulation of the damage process and device performance is developed. The model considers only the effect of ion exposure on the potential distribution within the metal-semiconductor junction. Comparison of experimental and modelled barrier shifts shows fair agreement, suggesting that enhancement of tunnelling currents is the dominant mechanism for barrier lowering.

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13

Anzenberg, Eitan. "Nanoscale surface structuring during ion bombardment of elemental semiconductors". Thesis, Boston University, 2013. https://hdl.handle.net/2144/12710.

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Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Nano-patterning of surfaces with uniform ion bombardment yields a rich phase-space of topographic patterns. Particle irradiation can cause surface ultra-smoothing or selforganized nanoscale pattern formation in surface topography. Topographic pattern formation has previously been attributed to the effects of the removal of target atoms by sputter erosion. In this thesis, the surface morphology evolution of Si(100) and Ge(100) during low energy ion bombardment of Ar+ and Kr+ ions, respectively, is studied. Our facilities for studies of surface processes at the National Synchrotron Light Source (NSLS) allow in-situ characterization of surface morphology evolution during ion bombardment using grazing incidence small angle x-ray scattering (GISAXS). This technique is used to measure in reciprocal space the kinetics of formation or decay of correlated nanostructures on the surface, effectively measuring the height-height correlations. A linear model is used to characterize the early time kinetic behavior during ion bombardment as a function of ion beam incidence angle. The curvature coefficients predicted by the widely used erosive model of Bradley and Harper are quantitatively negligible and of the wrong sign when compared to the observed effect in both Si and Ge. A mass-redistribution model explains the observed ultra-smoothing at low angles, exhibits an instability at higher angles, and predicts the observed 45° critical angle separating these two regimes in Si. The Ge surface evolution during Kr+ irradiation is qualitatively similar to that observed for Ar+ irradiation of Si at the same ion energy. However, the critical angle for Ge cannot be quantitatively reproduced by the simple mass redistribution model. Crater function theory, as developed by Norris et al., incorporates both mass redistributive and erosive effects, and predicts constraining relationships between curvature coefficients. These constraints are compared to experimental data of both Si and Ge. There is good agreement at low incidence angles; however, at higher angles the data disagrees with the predictions of the crater function formalism. This calls into question the ability of crater function theory to model the surface morphology evolution during ion bombardment.

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14

Chen, Liang-Yu. "Secondary ions sputtered by low energy ion bombardment of copper and aluminum surfaces". Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058535998.

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15

Hsieh, Jang-Hsing. "The effects of energetic particles bombardment on the properties of ion plated chromium thin films". Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/19489.

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16

Yewande, Emmanuel Oluwole. "Modelling and simulation of surface morphology driven by ion bombardment". Doctoral thesis, [S.l.] : [s.n.], 2006. http://webdoc.sub.gwdg.de/diss/2006/yewande.

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17

Katardjiev, I. V. "Theory and experimental studies of surface evolution during ion bombardment". Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234793.

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18

Kunkel, Gary John. "Interlaboratory comparisons of fast atom bombardment and liquid secondary ion mass spectra of diquaternary pyridinium oxime salts". Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/27336.

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19

Wang, Yang. "Theory of impact ionization in multiquantum well structures and its application to the modeling of avalanche photodiodes". Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/13405.

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20

Cross, T. A. "Radiation effects in AlxÌ²Ga1Ì²-Ì²xÌ²As and InP". Thesis, Lancaster University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379263.

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21

Payne, Robin Spencer. "Inert gas implantation of amorphous CuZr". Thesis, University of Surrey, 1987. http://epubs.surrey.ac.uk/847884/.

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It was proposed that amorphous alloys may be more resistant to radiation damage than crystalline metals. In crystalline metals neutron induced transmutations lead to the formation of inert gas bubbles. These preferentially nucleate near line defects and result in embrittlement. Amorphous alloys do not contain sites where nucleation can occur preferentially. In this work the growth of argon bubbles in amorphous Cu[50]Zr[50] has been induced by implanting thin specimens with 80keV argon ions at room temperature. The bubble size distribution was obtained over the dose range 5x10[16] to 3x10[17] Ar[+] cm[-2]. Larger bubbles grew in the amorphous alloy than would have been expected to grow in a crystalline metal implanted under the same conditions. It was found that ion bombardment caused surface atoms to be sputtered away from the specimens at a rate of 2.3at.ion[-1]. The sputtering process led to saturation in the amount of argon retained by the material and caused the formation of copper rich near-surface layer. This layer also contained significant amounts of oxygen. Blister formation was induced at the surface of the amorphous alloy by implanting it with 100keV helium ions. At a critical dose of 3x10[17] He[+]cm[-2] a population of very small blisters was formed. These were the result of large bubbles forming just below the specimen surface. As higher doses were used the features joined up to produce large, thin-lidded blisters at a dose of 10[18] He[+] cm[-2]. These observations could not be completely explained in terms of the two popular models of blister formation, where interbubble fracture or lateral stress result in surface deformation.

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22

Naylor, S. "Applications and mechanistic aspects of fast atom bombardment mass spectroscopy". Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234018.

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23

Chai, Meng Koon. "Modification of metal contacts to hydrogenated amorphous silicon by ion bombardment". Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/843707/.

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This thesis is concerned with the formation, characterisation and application of doped surface layers in hydrogenated amorphous silicon, a-Si:H. In this study, a-Si:H films have been deposited using a plasma enhanced chemical vapour deposition (PECVD) system and have been doped using ion implantation. In order to determine the efficiency of implantation doping various ion species, ion doses, and ion energies were made by direct implantation of impurities at low energies. Coupled with the annealing effect, the effect of doping on damage recovery has been studied. It has been shown that there is a good recovery of damage with annealing temperature, the optimum being = 250°C. In addition, it was found that the sequence of preparation steps can affect the electrical properties of the doped samples. Electrical properties of the doped surface layers have been determined from current-voltage measurements. This technique is based on the metal-semiconductor Schottky barrier as a characterisation tool with the aim of relating the current passing through a Schottky barrier to the total electrical activity in a surface layer. This is necessary due to the fact that the surface layer is very shallow, typically < 150 A deep, and that there is a small number of free carriers present in the layer. It has been shown that the effective barrier height of Schottky diodes on a-Si:H can be varied over a wide range using ion implantation of the common dopants. For small changes in barrier height, damage effects are negligible and dopant activity is high, leading to minimal changes in ideality factor and leakage current. Sheet resistance measurements of the amorphous silicide layers were made. It has been shown that a thin amorphous silicide can be formed by ion implantation via a radiation enhanced mechanism using low temperature processing.

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24

Brown, Douglas Andrew. "Theoretical study of two-dimensional charge densities in intense rectangular ion beams". Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185939.

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Beginning with its emergence from a high-aspect ratio rectangular aperture, the physics of an intense (current density ≳ 1 mA/cm²), positively charged ion beam is explored in two distinct regions: an electron-free drift region, and a beam plasma containing a large density of space-charge neutralizing electrons. In the drift region, the beam expands due to the mutual inter-ion Coulomb repulsion. Energy, mass, and phase-space density conservation are combined with Poisson's equation to obtain the beam ion density and resulting potential of the diverging beam at any point in 3-dimensional space. Within the beam plasma, the divergence rate is assumed negligible and the beam ion density at the drift/plasma interface taken to be the beam ion density throughout the beam plasma. It is assumed that collisions between beam ions and residual gas molecules, producing a steady generation of electrons and slow residual gas ions, is the dominant mechanism sustaining the beam plasma. Charge is conserved and the energy balance of the plasma examined to obtain the electron and slow-ion densities. Electron, slow-ion, and beam ion densities are then introduced into Poisson's equation to produce a second order partial integro-differential equation requiring a numerical solution. This solution is obtained by expanding the density and potential functions in a complete set of orthogonal (Chebyshev) functions and reducing the differential equation to a system of linear algebraic equations. Calculations in the drift region, for beams of 50, 100 and 500 keV, indicate that all intense beams, regardless of the initial aspect ratio, ultimately relax into the same, near Gaussian profile. In the beam plasma, the theory was applied to a 100 keV, high aspect ratio arsenic beam. The electron density profile is predicted to display a shape similar to that of the beam ions, with the resulting net potential possessing substantial cylindrical symmetry. Both the slow-ion and electron densities and hence the degree of space-charge neutralization, are found to depend strongly on the residual gas density.

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25

Green, Lisa Carol. "Fast atom bombardment mass spectra of pyrylium and pyridinium salts : the study of isotopic abundance ratios in various sputtering matrices". Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/27441.

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26

Little, Thomas William. "Surface science studies on the interaction of nitrogen trifluoride ion beams and plasmas with silicon /". Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/10613.

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27

King, Stanley W. "Mass transfer analysis of polyether sulfone and polyamide membranes modified by ion beam irradiation /". See Full Text at OhioLINK ETD Center (Requires Adobe Acrobat Reader for viewing), 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1083875419.

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Thesis (M.S.C.)--University of Toledo, 2004.
Typescript. "A thesis [submitted] as partial fulfillment of the requirements of the Master of Science degree in Chemical Engineering." Bibliography: leaves 109-113.

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28

Beckman, Michael William. "The effects of low pressure helium ion bombardment on hydrogenated amorphous silicon". [Ames, Iowa : Iowa State University], 2008.

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29

Liu, Joanne. "Scaling relationships for power deposition and ion bombardment in radio-frequency plasmas". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/31038.

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30

Epp, June Miriam. "The effects of ion bombardment on the chemical reactivity of GaAs(100)". Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54355.

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The effects of ion bombardment on the chemical reactivity of GaAs(100) were investigated by X-ray photoelectron spectroscopy. The enhancement in reactivity was shown to be related to the energy and mass of the bombarding ion. The oxidation results were compared to chemically cleaned (1:1 HCI(conc)/H₂O) and IHT (simultaneous ion/heat treatment) prepared GaAs(100). Before ion bombardment, GaAs(100) was chemically cleaned with 1:1 HCI(conc)/H₂O to remove surface oxides. Chemically cleaned GaAs was bombarded with 0.5-3 KeV Ar⁺ ions (fluences = 10¹⁶-10¹⁷ ions/cm²) and with 3 KeV Xe⁺, Ar⁺, ²⁰Ne⁺, and ³He⁺ ions (fluence =10¹⁷ ions/cm²) to investigate the effect of ion bombardment energy and mass on chemical reactivity. Ion bombardment results in the preferential sputtering of As and the amount of As depletion is dependent upon ion bombardment energy and mass. Following chemical cleaning and ion bombardment, GaAs was exposed to 10⁷-10¹³ L O2, 10⁹-10¹³ L H₂O,10⁶-10⁸ L NO, and 10⁷-10¹¹ L N₂O (1 Langmuir (L) = 1.3x10⁻⁴ Pa•sec). Chemically cleaned GaAs produced equivalent amounts of Ga₂O₃ and As₂O₃ upon O₂ exposure. Oxygen exposure of ion bombarded GaAs resulted in the formation of Ga₂O₃, As₂O₃, and As₂O₅. Nitric oxide exposure produced Ga₂O₃ and As₂O₃, and N₂O exposure produced only Ga₂O₃. Gallium oxide was preferentially formed for ion bombarded material and the relative amount of Ga₂O₃ increased with increasing ion energy. 3 KeV Xe⁺ ion-bombarded GaAs exhibited the greatest reactivity to O₂ and NO. Exposure of ion bombarded GaAs to NO produced the greatest amounts of Ga₂O₃. Ion bombarded GaAs was the least reactive to N₂O. Exposure of ion bombarded GaAs to H₂O resulted in the formation of GaOOH and Ga(OH)₃, with Ga(OH)₃ formation occurring only on 2 KeV Ar⁺ and 3 KeV Ar⁺ and Xe⁺ ion-bombarded material at exposures above 10¹⁰ L. It was shown that defects were responsible for the increased reactivity and that preferential formation of Ga₂O₃ on ion bombarded material was not determined by the Ga/As surface ratio. Exposing IHT prepared GaAs to O₂ produced equivalent amounts of Ga₂O₃ and As₂O₃ when the Ga/As ratio was 1.23±0.07. The damage caused by ion bombardment was investigated by optical reflectivity in the visible and near-ultraviolet region (1.6-5.6 eV), Raman spectroscopy, and capacitance-voltage measurements. Ion bombardment forms a damaged layer that is amorphous. The depth of damage is proportional to the energy of the bombarding ion and inversely proportional to the mass of the bombarding ion. The shallow damage depth for 3 KeV Xe⁺ ion-bombarded GaAs offers some explanation for increased chemical reactivity. The increased reactivity of ion bombarded GaAs with O₂ and NO is attributed to surface defects (broken surface bonds). It is suggested that these broken bonds are in the form of singly occupied dangling bonds. A model for the surface and possible reaction pathways for O₂ and NO reactions are discussed.
Ph. D.

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31

Osman, Sarah Omer Siddig. "Surface roughness of InP after N+2 bombardment : Ion areic dose dependence". Diss., University of Pretoria, 2004. http://hdl.handle.net/2263/24608.

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32

Sen, Sidhartha. "Electrical studies on ion-etched n-GaAs(100) surfaces". Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45915.

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The major objective of this thesis was to evaluate electrically the damage caused by a low energy (< 4keV) Ar⁺ bombardment on n-GaAs(100) surfaces. Electrical measurements were performed on Schottlky diodes formed on the virgin and the ion-etched surfaces.

The l-V measurements show deterioration of diode parameters by ion etching. The ion etched diodes have a strong component of surface leakage current. The high frequency capacitance of ion-etched diodes is less than that of the virgin diodes. The low frequency capacitance of ion-etched diodes was found to be frequency dispersive. The extent of frequency dispersion diminishes at low temperatures and at low reverse biases. Virgin diode capacitance, on the other hand, was found to be independent of frequency.

The electrical characteristics of ion-etched diodes are explained by means of an amorphous layer and a donor-like damaged layer formed as a result of ion etching. The depth of the top amorphous layer increases with etch energy. The damaged layer containing the ion induced traps superimposes over the amorphous layer and extends deep into the bulk semi-conductor. The density of such traps is very bias sensitive and also temperature dependent.

A possible equivalent circuit model for the ion-etched material is proposed. Low temperature isochronal annealing (< 450Â°C, 10mins.) was not found effective in causing complete recovery of the ion-damaged surface.

Master of Science

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33

Chen, Geng-Sheng. "Ion beam mixing of Mo/Al bilayer samples and thermal spike effects". Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/94500.

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Metallic bilayer samples of Mo(400 Å)/ Al(substrate) were characterized using Rutherford Backscattering Spectroscopy after first being irradiated with Xe ion beam having an energy of 1.8 MeV. The computer code RUMP was then used to simulate the RBS spectra. The interdiffusion at the interface was considered in terms of thermal spike induced atomic migration. It was found that the coupling of the chemical effect with spike is significant with regard to mixing of the bilayer samples. Furthermore, in addition to the initial contamination of carbon atoms on the surface and at the interface, more carbon atoms were found to be picked up by the surface, this carbon w.as from the vacuum pumps and tended to migrate into the surface once irradiation dose exceeded 11 x 10¹⁵cm². A semi-empirical model was developed for ion beam mixing taking into account collisional mixing and thermal spike effects, as well as the thermal spike shape. The collisional mixing part was accounted for by the Kinchin-Pease model, or, alternatively dynamic Monte Carlo simulation. For the thermal spike, the ion beam mixing parameter Dt/Φ was derived to be proportional to ( - F_D /ΔH_coh)^2+μ, where F_D is the damage energy deposited per unit path length, ΔH_coh is the cohesive energy of the target materials, and µ is a constant dependent on the spike shape and point defect density in the spike regions. The thermal spike introduces a nonlinear effect in the mixing process, distinguishing itself from the linear effect of ballistic mixing. The shape of the thermal spike that best fit the experimental results depends on the magnitude of the cascade density. For relatively high density collisional cascades, where thermal spikes start to be important, it was found that a spherical spike model was more consistent with experimental measurements at low temperatures. However, for extremely high density collisional cascade regions, a cylindrical shaped spike gave better results. The atomic migration energy in the spike regions is scaled by a factor of one out of 8.6 of cohesive energy. The migration mechanism was recognized to be interstitial-dominated one.
M.S.

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34

Ghalab, Sobhy Ahmed Nassar Ahmed. "Metal cluster sputtering under reactive ion bombardment investigated by TOF-SNMS-laser-system". kostenfrei, 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=97813592X.

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35

Choudhury, Tanima. "An XPS study of the effect of ion bombardment on transition metal oxides". Thesis, Aston University, 1991. http://publications.aston.ac.uk/25142/.

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36

Mohan, Krishnan R. "Fast atom bombardment mass spectrometry and tandem mass spectrometry : conditions for measurement of reproducible spectra". Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/27159.

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37

Wei, Yu. "Ion bombardment induced compositional changes in compound semiconductor surfaces by XPS combined with LEISS". Thesis, Aston University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282997.

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38

Al-Bayati, Amir H. H. "Radiation damage in Si(001) due to low energy Ar and Cl ion bombardment". Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280801.

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39

Yu, Lock See. "The effect of low energy ion bombardment on the crystallographic orientation of thin films". Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15310.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Includes bibliographical references.
by Lock See Yu.
M.S.

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40

Hwangbo, Chang Kwon. "Optical thin films prepared by ion-assisted and ultrasound-assisted deposition". Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184577.

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Optical, electrical, and microstructural effects of Ar ion bombardment and Ar incorporation on thermally evaporated Ag and Al thin films were investigated. The results show that as the momentum supplied to the growing films by the bombarding Ar ions per arriving metal atom increases, refractive index at 632.8 nm increases and extinction coefficient decreases, lattice spacing expands, grain size decreases, electrical resistivity increases, and trapped Ar increases slightly. In Ag films, stress reverses from tensile to compressive; in AI films compressive stress increases. In both films, the change in optical constants can be explained by variation in void volume. The reversal of stress from tensile to compressive in Ag films requires a threshold level of momentum. The increase in electrical resistivity is related to the increase in the void fraction, decrease in the grain size, and increase in trapped Ar in both types of films. Many of these properties correlate well with the momentum transferred, suggesting that the momentum is an important physical parameter in describing the influence of ion beams on growing thin films and determining the characteristics of thin metal films prepared by ion-assisted deposition (IAD). With a low energy ion beam, the Ar concentration in IAD Ag films was negligible. When the bombarded film thickness was less than 5 nm, the electrical resistivity of IAD Ag films tended to decrease slightly from that of the non-IAD film. Using the Bruggeman effective medium theory, a formula for the void fraction at any given wavelength was derived. We investigated optical properties, stoichiometry, chemical bonding states, and structure of aluminum oxynitride thin films prepared by reactive ion-assisted deposition. Variations of optical constants and chemical bonding states are related to the stoichiometry. We found that our amorphous aluminum oxynitride film is not simply a mixture of aluminum oxide and nitride but a compound. A rugate filter using a step-index profile of aluminum oxynitride films was fabricated by nitrogen ion beam bombardment of a growing Al film with backfilled oxygen pressure as the sole variable. The effects of ultrasound-assisted deposition (UAD) on the optical properties of ZrO₂, Ta₂O₅, and MgF₂ films were investigated. UAD is likely to induce oxygen and fluoride deficiencies in oxide and fluoride films and increase the packing density of films.

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41

Oates, Thomas William Henry. "Metal plasma immersion ion implantation and deposition using polymer substrates". Connect to full text, 2003. http://hdl.handle.net/2123/571.

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Thesis (Ph. D.)--University of Sydney, 2004.
Title from title screen (viewed 5 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Degree awarded 2004; thesis submitted 2003. Includes bibliographical references. Also available in print form.

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42

Numazawa, Satoshi. "Modeling of metal nanocluster growth on patterned substrates and surface pattern formation under ion bombardment". Forschungszentrum Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-93652.

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This thesis addresses the metal nanocluster growth process on prepatterned substrates, the development of atomistic simulation method with respect to an acceleration of the atomistic transition states, and the continuum model of the ion-beam inducing semiconductor surface pattern formation mechanism. Experimentally, highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO^2 surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well-separated. The first topic is the investigation of this growth process with a continuum theoretical approach to the surface gas condensation as well as an atomistic cluster growth model. The atomistic simulation model is a lattice-based kinetic Monte-Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag monomers and ≈1 nm square surface migration ranges of Ag monomers. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns. The second topic specifies the acceleration scheme utilized in the metallic cluster growth model. Concerning the atomistic movements, a classical harmonic transition state theory is considered and applied in discrete lattice cells with hierarchical transition levels. The model results in an effective reduction of KMC simulation steps by utilizing a classification scheme of transition levels for thermally activated atomistic diffusion processes. Thermally activated atomistic movements are considered as local transition events constrained in potential energy wells over certain local time periods. These processes are represented by Markov chains of multi-dimensional Boolean valued functions in three dimensional lattice space. The events inhibited by the barriers under a certain level are regarded as thermal fluctuations of the canonical ensemble and accepted freely. Consequently, the fluctuating system evolution process is implemented as a Markov chain of equivalence class objects. It is shown that the process can be characterized by the acceptance of metastable local transitions. The method is applied to a problem of Au and Ag cluster growth on a rippled surface. The simulation predicts the existence of a morphology dependent transition time limit from a local metastable to stable state for subsequent cluster growth by accretion. The third topic is the formation of ripple structures on ion bombarded semiconductor surfaces treated in the first topic as the prepatterned substrate of the metallic deposition. This intriguing phenomenon has been known since the 1960\'s and various theoretical approaches have been explored. These previous models are discussed and a new non-linear model is formulated, based on the local atomic flow and associated density change in the near surface region. Within this framework ripple structures are shown to form without the necessity to invoke surface diffusion or large sputtering as important mechanisms. The model can also be extended to the case where sputtering is important and it is shown that in this case, certain \\lq magic\' angles can occur at which the ripple patterns are most clearly defined. The results including some analytic solutions of the nonlinear equation of motions are in very good agreement with experimental observation.

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43

Yu, Wei. "Ion bombardment induced compositional changes in compound semiconductor surfaces studied by XPS combined with LEISS". Thesis, Aston University, 1995. http://publications.aston.ac.uk/8095/.

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Surface compositional change of GaP, GaAs, GaSb, InP, InAs, InSb, GeSi and CdSe single crystals due to low keV noble gas ion beam bombardment has been investigated by combining X-ray Photoelectron Spectroscopy (XPS) and Low Energy Ion Scattering Spectroscopy (LEISS). The purpose of using this complementary analytical method is to obtain more complete experimental evidence of ion beam modification in surfaces of compound semiconductors and GeSi alloy to improve the understanding of the mechanisms responsible for these effects. Before ion bombardment the sample surfaces were analysed nondestructively by Angular Resolved XPS (ARXPS) and LEISS to get the initial distribution of surface composition. Ion bombardment experiments were carried out using 3keV argon ions with beam current of 1A for a period of 50 minutes, compositional changes in the surfaces of compound semiconductors and GeSi alloy were monitored with normal XPS. After ion bombardment the surfaces were re-examined with ARXPS and LEISS. Both XPS and LEISS results showed clearly that ion bombardment will change the compositional distribution in the compound semiconductor and GeSi surfaces. In order to explain the observed experimental results, two major theories in this field, Sigmund linear collision cascade theory and the thermodynamic models based on bombardment induced Gibbsian surface segregation and diffusion, were investigated. Computer simulation using TRIM code was also carried out for assistance to the theoretical analysis. Combined the results obtained from XPS and LEISS analyses, ion bombardment induced compositional changes in compound semiconductor and GeSi surfaces are explained in terms of the bombardment induced Gibbsian surface segregation and diffusion.

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44

Winchell, Stephen D. "Transport imaging in the one dimensional limit". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FWinchell.pdf.

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45

Dodgson, John. "Ion-selective field-effect transistors with fast atom bombardment sputtered membranes for pH, sodium and potassium measurement". Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283651.

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46

Sangheera, Harpreet Kaur. "Investigation of the effects of low energy high dose ion bombardment in metals and compound semiconductors". Thesis, Aston University, 1998. http://publications.aston.ac.uk/7983/.

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The effect of low energy nitrogen molecular ion beam bombardment on metals and compound semiconductors has been studied, with the aim to investigate at the effects of ion and target properties. For this purpose, nitrogen ion implantation in aluminium, iron, copper, gold, GaAs and AIGaAs is studied using XPS and Angle Resolve XPS. A series of experimental studies on N+2 bombardment induced compositional changes, especially the amount of nitrogen retained in the target, were accomplished. Both monoenergetic implantation and non-monoenergetic ion implantation were investigated, using the VG Scientific ESCALAB 200D system and a d. c. plasma cell, respectively. When the samples, with the exception of gold, are exposed to air, native oxide layers are formed on the surfaces. In the case of monoenergetic implantation, the surfaces were cleaned using Ar+ beam bombardment prior to implantation. The materials were then bombarded with N2+ beam and eight sets of successful experiments were performed on each sample, using a rastered N2+ ion beam of energy of 2, 3, 4 and 5 keV with current densities of 1 μA/cm2 and 5 μA/cm22 for each energy. The bombarded samples were examined by ARXPS. After each complete implantation, XPS depth profiles were created using Ar+ beam at energy 2 ke V and current density 2 μA/cm2 . As the current density was chosen as one of the parameters, accurate determination of current density was very important. In the case of glow discharge, two sets of successful experiments were performed in each case, by exposing the samples to nitrogen plasma for the two conditions: at low pressure and high voltage and high pressure and low voltage. These samples were then examined by ARXPS. On the theoretical side, the major problem was prediction of the number of ions of an element that can be implanted in a given matrix. Although the programme is essentially on experimental study, but an attempt is being made to understand the current theoretical models, such as SATVAL, SUSPRE and TRIM. The experimental results were compared with theoretical predictions, in order to gain a better understanding of the mechanisms responsible. From the experimental results, considering possible experimental uncertainties, there is no evidence of significant variation in nitrogen saturation concentration with ion energy or ion current density in the range of 2-5 ke V, however, the retention characteristics of implantant seem to strongly depend on the chemical reactivity between ion species and target material. The experimental data suggests the presence of at least one thermal process. The discrepancy between the theoretical and experimental results could be the inability of the codes to account for molecular ion impact and thermal processes.

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47

Kwasnik, Mark. "Development and fundamental characterization of a nanoelectrospray ionization atmospheric pressure drift time ion mobility spectrometer". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33879.

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Drift time ion mobility spectrometry (DTIMS) is a rapid post ionization gas-phase separation technique that distinguishes between compounds based on their differences in reduced mass, charge and collisional cross-section while under a weak, time-invariant electric field. Standalone DTIMS is currently employed throughout the world for the detection of explosives, drugs and chemical-warfare agents. The coupling of IMS to MS (IM-MS) has enabled the performance of time-nested multidimensional separations with high sample throughput and enhanced peak capacity, allowing for the separation of ions not only based on their mass/charge (m/z) ratios, but also their shape. This allows for the elucidation of valuable structural information that can be utilized for determining gas phase ion conformation and differentiation between closely related ionic species. Over the past decade, these advances have transformed IM-MS applications and instrumental designs into one of the most rapidly growing areas of mass spectrometry. The work presented in this thesis is aimed at the development and subsequent characterization of a novel high-resolution resistive-glass atmospheric pressure DTIMS, and the application of this prototype DTIMS to the detection of environmentally relevant compounds. A review of the different types of ion mobility spectrometers, their principles of operation, and the advantages and disadvantages of each type are presented in Chapter 1. Chapter 2 describes the design and development of our prototype resistive glass DTIMS. A detailed description of the IMS hardware, including the ion sources, custom-built control computer, pulsing electronics, data acquisition system, and the timing schemes developed to operate the instrument in standalone DTIMS, multiplexed DTIMS, and IM-MS mode, are presented. Chapter 3 presents an initial characterization of the performance of a prototype resistive glass DTIMS under a wide range of instrumental parameters and also characterizes the radial ion distribution of the ions in the drift region of the spectrometer. Chapter 4 addresses the lack of sensitivity in DTIMS and explores ion trapping and multiplexing methods, introduces the principles of multiplexing and describes an extended multiplexing approach that encompasses arbitrary binary ion injection waveforms with variable duty cycles. Chapter 5 presents a detailed theoretical and experimental study of the separation power of our DTIMS and presents an evaluation of the field homogeneity and the performance of the ion gate.

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48

Jaichuen, C., R. Chundet, L. D. Yu, P. Thongkumkoon e S. Anuntalabhochai. "Effect on Genetic Mutation Induction from Nano-Ranged Low-Energy Plasma Ion Bombardment of DNA and Gene Fragment". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34948.

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49

Mokhtarzadeh, Mahsa. "Nano-patterning by ion bombardment". Thesis, 2018. https://hdl.handle.net/2144/34769.

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The bombardment of surfaces by ions can lead to the spontaneous formation of nano-structures. Depending on the irradiation conditions, smoothening or roughening mechanisms can be the leading order in pattern formation which can result in the creation of dots, ripples or ultra-smoothening effects. Because ion bombardment is already ubiquitous in industrial settings, and is relatively inexpensive compared to other surface processing techniques, self-organized patterning by ion bombardment could enable a simple, economical means of inducing well-defined nanoscale structures in a variety of settings. Understanding the fundamental behavior of surfaces during ion bombardment is therefore a vital goal; however, a complete understanding of physical processes governing surface pattern formation has not been reached yet. In order to address this issue, my thesis research has utilized three primary approaches. First, I have done real-time non-coherent X-ray scattering experiments at Cornell High Energy Synchrotron Source (CHESS) for studying kinetics of structure formation of Silicon undergoing Ar⁺ bombardment over a range of wavenumbers 4-5 times larger than has previously been obtained. From our data, we were able to extract values of the angle-dependent thickness of the amorphous layer that forms under ion bombardment, the ion-enhanced fluidity within that film, the magnitude of the stress being generated by the ion beam, and the strength of prompt atomic displacement mechanisms. Second, to further deepen our knowledge of surface dynamics, I have performed coherent X-ray studies of Ar⁺ bombardment of SiO₂ at the Advanced Photon Source (APS) for investigating the dynamics more profoundly than can be done with traditional time-resolved experiments. When using a focused ion beam, an inhomogeneous ripple motion was generated, this phenomenon reflected as an oscillatory behavior in the two-time and corresponding g₂(t) correlation functions. By fitting the oscillations in the g₂(t) correlation function, we have determined the surface ripple velocity on SiO₂ driven by Ar⁺ sputter erosion. Finally, to support the results of coherent X-ray experiments, simulations of growth models such as linear Kuramoto-Sivashinsky (KS) and Kardar-Parisi-Zhang (KPZ) have been carried out in order to compare the simulated temporal correlation functions of the scattered intensity with those obtained from the coherent x-ray scattering experiments.

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50

Höink, Volker. "Magnetoresistance and ion bombardment induced magnetic patterning /". 2008. http://nbn-resolving.de/urn/resolver.pl?urn=urn:nbn:de:hbz:361-12714.

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