bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Modification of Polytetrafluoroethylene by Ar+ Irradiation for Improving Adhesion to other Materials
Authors: Koh S. K. , Park S. C. , Seok J. W. , Choi S. C. , Choi W. K. , Jung H. J. 
Published: September 2012

AbstractIon Irradiation on polytetrafluoroethylene(PTFE) has been carried out to improve adhesion to metal and to adhesive cement. Argon ion was irradiated on the polymer, and amount of Ar+ was changed from 1014 ions/cm2 to l×1017 ions/cm2 at 1 keV, and 4 ml/min of oxygen gas was flowed near the polymer surface during the ion irradiation. Wetting angle was changed from 100 degree to 70 – 150 degree depending on the ion beam condition. The changes of wetting angle and effects of Ar+ irradiation in oxygen environment were explained in a view of surface morphology due to the ion beam irradiation onto PTFE and formation of hydrophilic group due to a reaction between irradiated polymer chain and the blown oxygen. Strongly enhanced adhesions were explained by interlock mechanism, formation of electron acceptor groups on the modified PTFE, and interfacial chemical reaction between the irradiated surface and the deposited materials.
Tunneling Current Change of Graphite Surface by Single Ion Irradiation
Authors: Ogiso H. , Mizutani W. , Nakano S. , Tokumoto H. , Yamanaka K. 
Published: September 2012

AbstractWe discuss changes in electronic structure and the topography of a graphite surface undergoing by a single ion impact. Protrusion-like regions (PLRs) found in a scanning tunneling microscope image disappeared in the same view of a noncontact atomic force microscope image. We measured tunneling current versus voltage characteristics to determine the density-of-states change in PLRs. We found that the density of states at the Fermi level of PLRs was greater than that of the intact surface. We therefore concluded that the PLRs were not actual topographical changes, but originated from electronic structural changes in semimetal to metal transition.
Quantitative Analysis of Chemically-Enhanced Sputtering during Ion Beam Deposition of Carbon Nitride Thin Films
Authors: Hofsäss H. , Ronning C. , Feldermann H. , Sebastian M. 
Published: September 2012

AbstractThe sputter losses during growth of carbon nitride thin films using mass selected ion beam deposition of C+ and N+ ions with energies between 20 eV and 500 eV are studied. Depending on the ion energy 35 – 100 % of C+ but only 3 – 35 % of N+ ions are incorporated in the films. Thus the films are always strongly nitrogen-deficient. To suppress the preferential loss of nitrogen we introduce the concept of continuously growing surface protective layers. Starting from a diamond-like carbon film as substrate, carbon nitride films are deposited using 100 eV 12C+ and 1 keV 14N+ ions, so that the growing films are always covered with a 1–2 rm thick protective layer of amorphous carbon. In this case we observe an increased nitrogen incorporation yielding to films with average film composition of C2N.
Pulsed Laser Deposition of Diamond-Like Carbon Thin Films: Ablation Dynamics and Growth
Authors: Yang Peidong , Zhang Z. John , Hu Jiangtao , Lieber Charles M. 
Published: September 2012

AbstractThin films of diamond-like carbon have been grown by pulsed laser deposition using a Nd:YAG laser at 532 nm. Time-of-flight mass spectroscopy was used to investigate the effects of laser power density and background gas pressure on the plume characteristics including the species in the plume and the kinetic energy distribution of each species. We found that with increasing laser power density (1) the relative amount of C+ ions increases, (2) the kinetic energy distributions of C+ get broader and can be deconvoluted into fast and slow components, and (3) the kinetic energy of the fast component of C+ ions increases from several to 40 eV. The resistivity and the local carbon bonding in films grown under these same conditions were also characterized. It was found that there is direct correlation between the characteristics of fast part of C+ ions in the plume and the diamond-like properties of the thin films. Under optimal growth conditions diamond-like carbon films with a large fraction of sp3 bonding can be prepared, although the maximum fraction appears to saturate at 70%. The implications of these results are discussed.
Mechanical and Tribological Properties of Chromium-Nitrogen Films Deposited by Ion Beam Assisted Deposition
Authors: Tobin E. J. , Namavar F. , Karimy H. F. , Colerico-Stenstrom C. , Bricault R. J. , Haupt Justus , Hirvonen J.-P. , Ayer R. 
Published: September 2012

AbstractMechanical and tribological properties of chromium-nitrogen films deposited by ion beam assisted deposition (IBAD) were investigated. The films were deposited reactively, i.e., via chromium evaporation with concurrent nitrogen ion beam bombardment, on stainless steel substrates at low deposition temperatures (<200°C). Two primary deposition regimes, with differing Cr/N atom-to-ion arrival ratios, were investigated: approximately 0.8–1.0 and 2.5–3.0. Rutherford Backscattering Spectroscopic analysis showed the lower arrival ratio films to be essentially stoichiometric CrN, whereas films deposited at higher arrival ratios were Cr-rich with Cr/N ratios of about 3:1. Both films were fine grained polycrystalline (typically 5–20 nanometer crystal dimension). The stoichiometric films were approximately two times harder than the Cr-rich films., based on nanohardness indentation measurements, and possessed higher residual stress levels. Both film types substantially improved the wear resistance of stainless steel disks, based on the results of ball-ondisk wear tests against ruby balls. The best performance was obtained with Cr-rich films, which exhibited a very low wear rate and lower friction than either the stoichiometric film or the uncoated steel.
Effects of Aluminum Implantation on the Oxidation Behavior of Silicon Nitride in a Sodium Nitrate-Oxygen Gas Mixture
Authors: Cheong Y. , Du H. , Withrow S. P. 
Published: September 2012

AbstractThe role of aluminum in negating the adverse effect of alkali species on the oxidation resistance of Si3N4 ceramics was investigated by exposing unimplanted and aluminum-implanted (1 and 5 at.%) Si3N4 samples to a sodium nitrate (95 ppm)-dry oxygen gas mixture at 1. atm and at 900°1100°C. Oxidation of unimplanted Si3N4 was rapid and linear with an activation energy of 57 kJ/mol. In contrast, samples implanted with aluminum exhibited a considerably reduced oxide growth which was parabolic in nature with activation energies of 103–112 kJ/mol. The morphological characteristics of the oxide layer also showed marked improvement as the aluminum concentration increased.
Surface Microchemistry Associated with Particle Bombardment on Ni(111)
Authors: Yang Jiun-Chan , Hwang Hsin-Yen , Chang Che-Chen 
Published: September 2012

AbstractThe influence of particle bombardment on surface reactivity is examined by using the reaction of CO on the Ni(111) surface as a model system. Thermal desorption studies shows that a large amount of residual CO may be deposited on the surface during ion bombardment. An appreciable amount of oxygen can be produced on the surface by collision-induced CO dissociation. A new dlesorption state of CO is also formed. The activation energy for CO desorption from this new state is estimated to be about 90 kJ/mol, which corresponds to a decrease of the C-Ni bond energy of 25 – 30 kJ/mol as the sample evolves from a smooth to a damaged state. The dipole-dipole repulsion is present between CO molecules adsorbed on the ion-bombarded surface, which causes CO to desorb at a lower temperature for higher CO exposures. Under similar bombardment conditions, the sticking probability of CO on the bombarded surface decreases with decreasing momentum of the impinging particle.
The Influence of Cerium Ion Implantation on Early-Stage Oxidation Kinetics of Nickel
Authors: Czerwinski F. , Szpunar J. A. 
Published: September 2012

AbstractThe effect of implantation with 2×1016 ions/cm2 at 150 keV Ce+on the oxidation of polycrystalline high purity Ni was examined. The radiation damage and distribution of Ce implants in Ni substrate were additionally modified by post-implantation ultra-high vacuum annealing at 1073 K. Ce implants decreased the Ni oxidation rate at 973 K by approximately one order of magnitude, and this reduction was similar to that achieved by 14 nm thick CeO2 sol-gel coatings and by 4 nm thick coatings of CeO2 deposited on the same substrate by reactive sputtering. Physical damage introduced by radiation caused a slight increase in oxidation rate during the very initial stages. However, the essential improvement in the oxidation resistance was derived entirely from the chemical role of the implants. The beneficial effect of Ce was reduced when the implanted Ni substrate was vacuum-annealed prior to the oxidation.
Stress Induced Extended Ranges for Hydration and Other Phenomena in Ion Implanted Silica Glasses
Authors: Arnold G. W. , Battaglin G. 
Published: September 2012

AbstractThe extended ranges (2–3 times theoretical) for hydration from an ambient atmosphere or water immersion and other anomalous ranges for property changes in ion-implanted fused silica are explained on the basis of a stress corrosion model (Michalske-Bunker). The results for the hydration of implanted soda-lime glass are similar to fused silica with the added feature of compositional modification due to the near-surface removal of alkali.
Grain-Size and Impurity Effects in Low-Temperature Deposition of TiN
Authors: Kakimy H. , Namavar F. , Tobin E. , Haupt J. , Bricault R. , Hirvonen J. P. , Ayer R. 
Published: September 2012

AbstractCommercially deposited titanium nitride (TIN) thin films have been available daring recent years. These TiN films possess high hardness and have good wear resistance; however, the deposition process typically requires a temperature of 500°C or higher. In many cases, due to substrate characteristics, a deposition temperature below 150°C is required in order to exploit TiN coating properties.The objective of this work is to demonstrate that ion beam assisted deposition (IBAD) makes it possible to deposit gold-color TiN films with good adhesion onto a variety of substrates including plastics at temperatures below 150°C. These films have physical and mechanical properties as good as those produced at high temperatures. Samples have also been examined by nanohardness techniques to accurately determine the hardness of the films and relate them to process parameters and crystal sizes. Our results indicate that, by controlling the grain size of TiN, it is possible to fabricate TiN coatings at room temperature with hardness as high as 25.5 ± 1 GPa.
Competition Between Gettering by Implantation-Induced Cavities in Silicon and Internal Gettering Associated with SIO2 Precipitation
Authors: McHugo S. A. , Weber E. R. , Myers S. M. , Petersen G. A. 
Published: September 2012

AbstractThe gettering behavior of Cu and Fe was investigated in CZ silicon containing both internal-gettering sites in the bulk due to SiO2 precipitation and a device-side layer of cavities formed by He ion implantation and annealing. The objective was to quantify the effectiveness of impurity gettering at cavities relative to the widely used internal-gettering process. Both rapid thermal anneals and furnace anneals were used during the gettering sequences to reveal transient effects as well as the final, thermodynamically-equilibrated condition. For temperatures of 700, 800 and 850°C, the cavity gettering was observed to dominate the internal gettering as indicated both by the number of gettered atoms in the cavities and the residual solution concentration in the device region. The results are interpreted in detail by numerically solving the diffusion equation with sink-related source terms based on earlier, fundamental studies of the underlying mechanisms of internal and cavity gettering.
Diffuse X-Ray Scattering Study of Defects Created by keV Ion Implants in Si
Authors: Partyka P. J. , Averback R. S. , Nordlund K. , Robinson I. K. , Walko D. , Ehrhart P. , Rubia T. Diaz de la , Tang M. 
Published: September 2012

AbstractDiffuse x-ray scattering (DXS) and computer simulation techniques were employed to investigate the defect structure produced in Si by low keV ion and MeV electron irradiations. DXS measurements were performed for keV Ga and He implants, demonstrating the ability of the technique to provide both bulk and near-surface measurements at defect concentrations of about 1000 ppm. A rigorous analysis of these results is complicated due to the complex nature of the ion damage in Si. A computer simulation framework is developed to aid in the analysis of this data. In this technique, defects are simulated and their strain fields are calculated by simply relaxing the atoms around the defect to their equilibrium positions. The diffuse scattering is then calculated from the strain field, and the results are compared to the experimental measurements. Computer simulations are presented here only for the case of electron irradiation damage and compared to published measurements.1 Application of the technique to more complicated structures is planned and should pose no serious problems in the computational framework already developed.
Modeling of Damage Evolution During Ion Implantation into Silicon: a Monte Carlo Approach
Authors: Tian S. , Morris M. , Morris S. J. , Obradovic B. , Tasch A. F. 
Published: September 2012

AbstractWe present for the first time a physically based ion implantation damage model which successfully predicts both the as-implanted impurity range profiles and the damage profiles for a wide range of implant conditions for arsenic, boron, phosphorus, and BF2 implants into single-crystal (100) silicon. In addition, the amorphous layer thicknesses predicted by this damage model for high dose implants are also generally in excellent agreement with experiments. This damage model explicitly simulates the defect production and its subsequent evolution into the experimentally observable profiles for the first time. The microscopic mechanisms for damage evolution are further discussed.
In Situ Optical Observation and Control of Initial Stages of GaAs Growth On Caf2 Surface Modified by Electron Beam Irradiation
Authors: Kawasaki K. , Tsutsui K. 
Published: September 2012

AbstractWe investigated the electron beam induced surface modification of CaF2(1 11) and initial stage of GaAs growth on the modified CaF2 surface by means of the surface photoabsorption technique and atomic force microscopy (AFM). The CaF2 surface was modified by 300 eV electron beam irradiation at 200°C in a As4 molecular beam. The amount of adsorbed As atoms increased with electron dose and it follows Langmuir adsorption principle and saturated at a value equivalent to I monolayer adsorption. In situ observation of GaAs growth on this modified surface clarified that the sticking coefficient of GaAs on CaF2 surface was drastically improved by the surface modification. AFM observation revealed that the surface roughness of initial growth of GaAs on modified CaF2 was improved at the growth temperature of 550°C
Surfactant-Mediated Si/Ge Epitaxial Crystal Growth
Authors: Kim Eunja , Wuk OH Chan , Lee Young Hee 
Published: September 2012

AbstractWe investigate the kinetic role of a surfactant in the epitaxial Si/Ge crystal growth using ab initio molecular dynamics approach. We examine the previously suggested dimer-exchange mechanisms and find that kinetics plays a crucial role in determining the exchange process. We further find that the diffusion of adatoms on an island in the presence of a surfactant is quite different from the dimer-exchange process on a flat surface.
Interface Roughness in Strained Si/SiGe Multilayers
Authors: Darhuber A. A. , Holy V. , Stangl J. , Bauer G. , NÜtzel J. , Abstreiter G. 
Published: September 2012

AbstractDiffuse x-ray reflection from a SiGe/Si multilayer grown pseudomorphically on slightly miscut Si(OOl) substrates has been studied theoretically and experimentally. In the framework of the Distorted-Wave Born Approximation (DWBA), we demonstrated that the distribution of the diffusely scattered intensity gives conclusive information on both the amount and the in-plane and inter-plane correlation properties of the interface roughness. The best model for the description of the interface-morphology was found to be a combination of a two-level model and a staircase model.
Modification of the Surface Band-Bending of A Silicon CCD for Low-Energy Electron Detection
Authors: Smith Aimée L. , Yu Qiuming , Elliott S. T. , Tombrello T.A. , Nikzad Shouleh 
Published: September 2012

AbstractSilicon CCDs have limited sensitivity to particles and photons with short penetration depth, due to the surface depletion caused by the inherent positive charge in the native oxide. Because of surface depletion, internally-generated electrons are trapped near the irradiated surface and therefore cannot be transported to the detection circuitry. This deleterious surface potential can be eliminated by low-temperature molecular beam epitaxial (MBE) growth of a delta-doped layer on the Si surface. This effect has been demonstrated through achievement of 100% internal quantum efficiency for UV photons detected with delta-doped CCDs.In this paper, we will discuss the modification of the band bending near the CCD surface by low-temperature MBE and report the application of delta-doped CCDs to low-energy electron detection. We show that modification of the surface can greatly improve sensitivity to low-energy electrons. Measurements comparing the response of delta-doped CCDs with untreated CCDs were made in the 50 eV-1.5 keV energy range. For electrons with energies below 300 eV, the signal from untreated CCDs was below the detection limit for our apparatus, and data are presented only for the response of delta-doped CCDs at these energies. The effects of multiple electron hole pair (EHP) production and backscattering on the observed signals are discussed.
A Self-Organized Molecular Beam Epitaxial Growth of the InSb/AlGaSb Quantum Dots on High-Index GaAs Substrates
Authors: Yano Mitsuaki , Koike Kazuto , Inoue Masataka , Saitoh Toshiya , Yoh Kanji 
Published: September 2012

AbstractIn-situ organization of InSb quantum dots on Al0.5Ga0.5Sb is reported. Samples were grown on just (100), 5°off (100) towards [0-1-1],(311)A, and (311)B surfaces of GaAs by molecular beam epitaxy. The growth mechanism and characteristics of quantum dots were analyzed using reflection high-energy electron diffraction, atomic force microscopy, and photoluminescence. Observed photoluminescence peak shift towards lower energy side with InSb thickness was interpreted by the development of quantum dots. Substrate orientation effect was examined and found to be useful to increase the dot density. As a result, as high as ~3xl 09 cm-2 dot density was achieved on the (311 )B substrate whereas the typical value on the (100) was ~2xl 08 cm-2 .
Antimony Cluster Manipulation on the Si(001) Surface by Means of STM
Authors: Kravchenko I.I. , Salling C.T. , Lagally M.G. 
Published: September 2012

AbstractWe present results of the manipulation of antimony clusters on Si(001) by means of a scanning tunneling microscope. By adjusting tip-sample separation and pulse voltage, an antimony cluster can be removed from the sample surface without damaging it. The success rate of the removed-cluster redeposition from the tip back onto the surface is 30%. In the remainder of the attempts a square shaped structure is created that had a hillock in the center. The hillock exhibits a metallic-like I-V curve. Such a structure cannot be created without an Sb cluster previously removed from the surface and located on the tip.
Surface Morphology of Nanoscale TiSi2 Epitaxial Islands on Si(00l)
Authors: Yang Woochul , Jedema F.J. , Ade H. , Nemanich R.J 
Published: September 2012

AbstractThe morphologies of nanoscale epitaxial islands of TISi2 are studied. The islands are prepared by deposition of ultrathin Ti (3-20Å) on both smooth and roughened.Si(001) substrates. The island formation is initiated by annealing to 800-1000°C. The roughened substrates are prepared by etching with atomic H produced in a plasma. The morphologies of the substrate before and after island formation are examined by atomic force microscopy (AFM). In particular, the influence of surface-roughness on both the formation of islands and the size distribution of islands is investigated. On a rough substrate islands with a lateral dimension of ~350Å and a vertical dimension of ~25Å were observed with size uniformity of ~20%. Also it was observed that the roughness of the surface reduced the island size and affected the island distribution. The results are discussed in terms of surface energy and the strain field around the islands.
Structural Defects in Thick Ingaas Layers Grown by Lpee on Partially Masked GaAs Substrates
Authors: BRYSKIEWICZ T. 
Published: September 2012

AbstractDefect formation in thick InxGa1-xAs layers, 0.06 ≤ x ≤ 0.17, grown by liquid phase electroepitaxy (LPEE) on partially masked GaAs substrates has been studied. The InxGa1-xAs ingots were 6 mm in thickness and, in some cases, more than 53 mm long in one direction. Prior to the LPEE growth, a thin SiO2 layer was deposited on the (100) oriented GaAs substrate by plasma enhanced chemical vapor deposition (PECVD), and patterned by photolithography with oxide free seeding windows of different geometry. The growth of a ternary crystal from a slightly supercooled melt originated in the form of islands within the window areas and extended laterally over the SiO2 layer to result, as the growth proceeded by LPEE, in a continuous layer with no apparent boundaries between merging islands. The two main structural defects have been identified in these compositionally uniform ternary crystals: microtwins and microcracks. They were found to result from the crystal/substrate misfit stress, when insufficiently suppressed by the SiO2 layer, and/or from improper seeding window geometry. The microcrack and microtwin formation in large diameter InxGa1-xAs crystals has been suppressed by the right choice of the seeding window geometry as well as by minimizing damage to the SiO2 layer caused by the H2 atmosphere and high growth temperature.
Facet Formation in Submicron Selective Growth of Si/SiGe
Authors: Wang K. L. , Wang Dawen 
Published: September 2012

AbstractThe paper reviews the work in mostly Si and SiGe epitaxy and some III-V work on patterned
substrates. Results of metalorganic chemical vapor deposition (MOCVD), low pressure chemical vapor deposition (LPCVD), gas source molecular beam epitaxy (GSMBE), and solid source molecular beam epitaxy (MBE) were discussed in the context of facet formation and mass accumulation. A model was shown to explain the facet formation and its evolution in the process of growth. Further work on surface diffusion and nucleation processes as functions of temperature and other growth parameters will provide needed information for accurate modeling of the facet growth process.