bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flexibility Of The Zeolite Rho Framework: The Redistribution Of Extra Framework Cations As A Function Of Temperature.
Authors: Parise John B. , Liu Xing , Corbin David R. , Jones Glover A. 
Published: March 2011

ABSTRACTUpon heating Ba2+, Sr2+ and Cd2+-exchanged zeolite RHO, abrupt changes have been observed in the cubic unit cell parameters [1–3]. Calculations of the powder x-ray diffraction patterns indicate these changes result from relocation of the extra-framework cations. For Ba2+ and Sr2+-exchanged RHO, a shift from the single 8-ring (S8R) to the double 8-ring (D8R)-site is accompanied by contraction of the unit cell. However, for the Cd2+-exchanged material relocation from the S8R to the single 6-ring (S6R)-site coincides with cell expansion. Further, with relocation of Cd2+ the low temperature acentric (A) form is transformed to a centric (C) structure above 300°C. The shift of Cd2+ ion occurs over a distance of 5.7Å, the largest observed in a zeolite.
129Xe Nmr As A Probe Of Microporous Materials
Authors: Ripmeester John A. , Ratcliffe Christopher I. 
Published: March 2011

ABSTRACTIt is shown that the interpretation of 129Xe chemical shift measurements in microporous solids is not simple, and that considerable caution must be used both in the measurement and interpretation of results, especially for large pore systems. Nevertheless, useful information can be obtained on the phase diagram of xenon in pore systems, and on transport within the solid and between the solid and the gas phase.
Ultrathin Soi Structures by Low Energy Oxygen Implantation
Authors: Namavar Fereydoon , Cortesi E. , Buchanan B. , Manke J. M. , Kalkhoran N. M. 
Published: March 2011

ABSTRACTAlthough silicon-on-insulator (SOI) materials made by standard energy (150–200 keV) SIMOX processes have shown great promise for meeting the needs of radiation hard microelectronics, there are still problems relating to the radiation hardness and economic viability of standard SIMOX. A low energy SIMOX (LES) process reduces cost and improves radiation hardness and increased throughput of any implanter because much smaller doses are required. In addition, the process is uniquely able to produce high quality thin SIMOX structures that are of particular interest for fully depleted device structures. In this paper, we address the formation of high quality ultrathin SIMOX structures by low energy implantation.
Dynamics of Change in Electrical Conductivity of Ion Irradiated Amorphous Silicon.
Authors: Shin Jung H. , Im J. S. , Atwater H. A. 
Published: March 2011

ABSTRACTThe dynamics of relaxation of amorphous silicon after unrelaxation (creation of defects) by irradiation with 600 KeV Kr++ ions is investigated using the changes in electrical conductivity of amorphous silicon. By measuring the conductivity of such unrelaxed amorphous silicon after being partially relaxed by isochronal anneals in a temperature range from 383 to 873° K, it is shown that conductivity of amorphous silicon decreases monotonically by up to 3 orders of magnitude as it relaxes; i.e. that conductivity is a measure of the degree of relaxation. Furthermore, it is found that such change in conductivity can be completely reversed by a subsequent unrelaxation with ion irradiation. Continuous in situ measurements of conductivity of amorphous silicon before, during and immediately after irradiation in a temperature range from 77 to 573° K show that relaxation occurs even at 77°K. Finally, the relaxation of amorphous silicon thus measured is linear when plotted against ln(t), a behavior that is characteristic of relaxation with a spectrum of activation energies.
Growth of ion implanted buried FeSi2 on Si (111) and Si (100)
Authors: Radermacher K. , Mantl S. , Dieker Ch. , Holzbrecher H. , Speier W. , Lüth H. 
Published: March 2011

ABSTRACTBuried FeSi2 layers have been fabricated by 200 keV Fe+ implantations into (111) and (100) Si substrates. By varying the dose from 0.4 to 7.1017 Fe+ cm−2 the dependence of the Fe concentration on ion dose was investigated systematically. The samples were characterized by Rutherford backscattering spectrometry, He+ ion channeling and secondary ion mass spectroscopy. In the as-implanted state the Fe peak concentration increases lineary with dose up to ≈2.4.1017 Fe+ cm−2. Above this dose a redistribution of Fe atoms was observed as indicated by comparison of measured depth profiles with Monte-Carlo simulations of high dose implantations. The Fe peak concentration shows an unusual dose dependence after rapid thermal annealing (RTA) at 1150°C for 10 s. A minimum dose of (2.4±0.1)1017 Fe+ cm−2 for (111) Si and a slightly higher dose of (2.7±0.1).1017 Fe+ cm−2 for (100) Si is necessary to form continuous metallic αFeSi2 layers.
XPS Investigation of Ion Implanted PMMA
Authors: Kallweit R. , Roll U. , Strack H. , Pocker A. 
Published: March 2011

ABSTRACTDuring ion bombardment, polymethylmethacrylate (PMMA) shows degassing of polymer components with a fluence and energy dependent contraction of the material, which leads to a material modification.The ion beam induced chemical modification of the implanted layers was examined by means of X-ray photoelectron spectroscopy (XPS). The dependence of the chemical modification on beam current, ion fluence and ion energy was investigated for nitrogen implantations at energies ranging from 50 keV to 400 keV for ion fluences between 7×1013 / cm2 and 7×1015/cm2. Compared with the C-spectrum of virgin PMMA, the spectra of the implanted layers exhibited an increase of intensity of the 284.5 eV peak and the 286.4 eV peak. The ion beam induced modification led basically to generation of new C-o-groups. These generations show drastical changes in the dependence of the beam current and the ion fluence. Nevertheless, at a constant dose of 2×1014/cm2 the concentrations of the new groups did not indicate any energy dependence.
A New Method for Measuring Ion Implantation Amorphous Dose In Situ
Authors: Yuan Jianzhong , Verner Igor V. , Corbett James W. 
Published: March 2011

ABSTRACTAn in situ method for determining the ion implantation dose necessary to make Si amorphous is developed and utilized. This method is based on measuring ion-implantation-induced in-plane stress. Measurements are carried out for various low energy ions implanted into thin p-type (100) Si. The doses necessary to make Si amorphous obtained by this method are in good agreement with previous data. This technique is sensitive, informative, quick, visual and nondestructive.
Mossbauer Study of the Role of Aluminum and Chromium in Nitrogen Implanted Iron
Authors: Kopcewicz M. , Jagielski J. , Turos A. , Williamson D. L. 
Published: March 2011

ABSTRACTThe role of alloying elements such as Cr and Al in the formation and stability of the nitride phases formed due to N ion implantation into metallic iron was studied by conversion electron Mössbauer spectroscopy (CEMS). The thermal stability of nitride phases upon 1 h annealing was greatly increased as a result of co-implanting either Cr or Al with N as compared to pure α-Fe implanted only with N.
The Effect of Thermal Spike on the Ion Irradiation Induced Grain Growth
Authors: Chae K. H. , Song J. H. , Joo J. H. , Woo J. J. , Whang C. N. , Oh Y. J. , Jung H. J. 
Published: March 2011

ABSTRACTThe relation between the ion irradiation induced grain growth in bilayer system and the basic parameters involved in ion beam mixing process was studied. TEM micrographs showed that a significant grain growth has been induced by Ar+ irradiation at room temperature. The grain size increases rapidly in low dose region, while it approaches a saturated value in high dose region, and it has close relationship with thermodynamic properties such as cohesive energy ( ΔHc ) and heat of mixing( ΔHm ). The experimental results are in good agreement with the model for the grain growth based on the thermal spike induced atomic migration.
Novel Paths for Nucleatton and Growth of Thin Films by Ionized Cluster Beam (ICB) Techniques: Atomic-Scale Observations
Authors: Yamada I. , Yamada T. , Takaoka G. H. , Usui H. , Current M. I. 
Published: March 2011

ABSTRACTAtomic-scale observations by STM and TEM of the early stages of film growth and recent studies of the detailed composition of beams from ICB sources have led to new understandings of origins of some of the extraordinary properties of thin films deposited by ICB methods. The presence of a small fraction of atoms in the form of large clusters initiates a novel sequence of film growth steps starting with the immediate formation of stable islands for film growth. The growth of films from cluster-initiated islands leads to fundamentally altered film properties (compared to atomic beam, MBE, deposition) such as the epitaxial alignment of metal/semiconductor/ceramic multilayers grown near room temperature.
Formation of Aluminum Films Using a High Rate ICB Source
Authors: Tsukazaki H. , Okamoto G. , Hashimoto Y. , Yamanishi K. , Tanaka M. , Yasunaga S. 
Published: March 2011

ABSTRACTAn ionized cluster beam (ICB) source has been developed for high rate deposition, and its possible application to ultra large scale integrated circuit (ULSI) metallization was investigated. Aluminum films were deposited onto oxidized silicon wafers using the ICB source. It was shown that an electrical resistivity was almost the same as the value for bulk aluminum, and the surface morphology of deposited films was improved by controlling the ionization and acceleration conditions of the cluster beam. It was confirmed that the ICB method showed an excellent coverage profile in contact holes when compared with the conventional sputtering method. Using the directivity of cluster beams, contact holes of 1.5 in aspect ratio were successfully metallized. From these results, it became evident that the ICB source is a favorable method for ULSI metallization.
TEM Study of Flux Pinning Defects in YBa2Cu3O7-δProduced by 580 MeV Sn Ion Irradiation
Authors: Wheeler R. , Kirk M. A. , Brown R. , Marwick A. D. , Civale L. , Holtzberg F. H. 
Published: March 2011

ABSTRACTRecent studies of high Tc superconductors irradiated with high energy heavy ions have indicated that a defect structure is produced which is extremely effective in pinning magnetic flux lines. In attempting to develop models to account for these observations, it is imperative to have a complete characterization of the defects responsible for the property enhancements. Hence, the defect microstructure produced in single crystal YBCO by 580 MeV Sn30+ irradiation, recently demonstrated to provide highly effective flux pinning at high fields and temperatures, has been investigated by conventional transmission electron microscopy. This irradiation condition is shown to produce linear, yet segmented, tracks of damaged material, approximately aligned with the incident irradiation direction, throughout the entire crystal thickness of 22μm. The cross sectional density of damage tracks is in close agreement with the ion fluence. Two specific characteristics of the track morphology have been studied, namely, their continuity and angular spread. The continuity of the tracks does not appear to follow threshold-like behavior within the electronic loss range studied here and the angular distribution of the defect track directions is only approximated by the Monte Carlo calculations of TRIM.
Nanoscale Y2O3 Phase Dispersion in YBa2Cu3O7−x Thin Films Produced by Plasma-Enhanced Metalorganic Chemical Vapor Deposition
Authors: Lu P. , Zhao J. , Chern C. S. , Li Y. Q. , Kulesha G. A. , Gallois B. , Norris P. , Kear B. , Cosandey F. 
Published: March 2011

ABSTRACTTransmission electron microscopy has been used to investigate the microstructure of YBa2Cu3O7−x thin films deposited by Plasma-Enhanced Metalorganic Chemical Vapor Deposition. The films with the best superconducting properties of Tc ∼90K and Jc>106A/cm2 at 77K and OT were either Y-rich or both Y- and Cu-rich relative to the ideal 1:2:3 composition. In the Y-rich thin films, nanoscale yttria(Y2O3) precipitates have been identified. The precipitates with an average size of about 50Å and densities as high as 1024/m3 are uniformly distributed and highly oriented with respect to the matrix. Excess Cu in the Cu- and Y-rich films leads to formation of large CuO particles on the film surface but does not have any effect on formation of nanoscale Y2O3 phase within the films. The Y2O3 precipitates may act as flux pinning sites for high critical current densities.
Low Energy Ion Beam Modification of High Performance Polymer
Authors: Jeong Hyo-Soo , White R. C. 
Published: March 2011

ABSTRACTIon beam modification of polyimide (PI) by low energy and surface analysis were performed using XPS. The surface chemistry was monitored as a function of ion dose. The results indicate that even low energy ion beam (LEIB) induces a drastic change in chemical compositions on the PI surface, and the modification begins to occur at the onset of beam treatment, contrary to previous observations. Damage level is severely restricted to surface region. It is also proven that LEIB modification is a direct way to control interface chemistry.
Low-Energy AR+ Implantation of Uhmw-Pe Fibers: Effect on Surface Energy, Chemistry, and Adhesion Characteristics
Authors: Schalek R. , Hlavacek M. , Grummon D. S. 
Published: March 2011

ABSTRACTUltra-high molecular weight polyethylene (UHMW-PE) has a highly chain-extended and crystalline structure which is functionally inert and requires surface-modification before it can successfully operate as a reinforcement in polymer-matrix composites. Although plasma treatments are adequate for this purpose, recent work has shown that irradiation with low-energy inert gas ions can produce increases in interfacial shear strength (ISS), in epoxy matrices, which exceed those of commercial plasma treatments, and cause little degradation in tensile properties. Low energy ions are readily produced in high-current beams using gridded sources having moderate cost, and processing times may be a short as a few seconds. In this paper, we present results of recent experiments using argon ions accelerated to energies between 100 eV and 1 keV to irradiate 20–30 μm diameter UHMW-PE fibers to doses between 1×1016 and 1×1017 cm−2, and compare our findings with previous work at higher accelerating potentials. At the optimum dose (which increases with decreasing energy), greater than 9-fold improvements in ISS level, measured in epoxy-resin droplet pulloff tests, were found for ion irradiation at 0.25 keV. Scanning electron microscopy of fiber surfaces, of ion irradiated as well as commercial oxygen plasma-treated materials, revealed small crack-like pits in both cases, with the pits smaller and more uniformly distributed on the ion-irradiated fibers. Surface chemistry studies using X-ray photoelec-tron spectroscopy (XPS) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) indicate that irradiation resulted in high surface concentrations of polar functional groups, and extensive surface oxidation. This was accompanied by a substantial increase in the polar component of surface energy, which resulted in improved fiber wetting by the resin.
Origin of the Laser-Induced Broad Band Luminescence from a WF6/H2/Ar Gas Mixture
Authors: Heszler P. , Mogyorósi P. , Carlsson J.O. 
Published: March 2011

AbstractThe origin of the ArF excimer laser induced luminescence from a WF6/H2/Ar gas mixture was investigated. The experiments prove that the emission originates from excited W clusters with a size of about 10-20 nm. The influence of the H2 and Ar concentrations, the laser fluence and the repetition rate on the light intensity was studied.
Demonstrating the Utility of Boron Based Precursor Molecules for Selective Area DepositIon in a Scanning Tunnelling Microscope
Authors: Perkins F. Keith , Onellion M. , Lee Sunwoo , Dowben P.A. 
Published: March 2011

AbstractThe scanning tunnelling microscope (STM) can be used to selectively deposit material from a gaseous precursor compound. Ultrasmall (less than a 100 nm across) spatial dimensions for selective area deposition may be achieved by this means. In this paper we outline a scheme forselecting and designing main group cluster compounds and organometallics for this type of selective area deposition using nido-decaborane(14) as an example.
The Formation of Rugged Surface Polycrystalline Silicon Using Cl2/O2 Plasmas: The Role of Oxygen
Authors: Ozawa N. , Ikegami N. , Miyakawa Y. , Kanamori J. 
Published: March 2011

AbstractThe formation of rugged surface polycrystalline silicon (poly-Si) using Cl2/O2 plasmas in which O2 concentration is 0-10 % has been investigated. Phosphorus doped poly-Si (n+ poly-Si) surface is rugged by the plasma etching under the condition that O2 concentration are 1-5 % at 10 Pa, but is not rugged at 1.3 Pa. On the other hand, undoped poly-Si surface is not rugged in Cl2 /0-10 %O2 plasmas at 10 Pa. Oxygen and phosphorus play an important role in the ruggedness of n+ poly-Si. The ruggedness mechanism has been investigated using scanning electron microscope, optical emission spectroscopy and mass spectrometry. The ruggedness mechanism is suggested that in Cl2 plasmas added a small amount of oxygen, n+ poly-Si is etched selectively at the grain boundaries which contain more phosphorus than in grains. The Cl emission intensity and n+ poly-Si etch rate reach maximum in Cl2/3 %O2 plasma at 1.3 Pa. Oxygen has a possibility of promoting SiCIx dissociation and increasing Cl radicals.
Molecular Dynamics Simulations and Experimental Evidence for Deep Penetration by Channeled Ions During Low-Energy Ion Bombardment of III-V Semiconductors
Authors: Stoffel N.G. , Schwarz S.A. , Pudensi M.A.A. , Kash K. , Florez L.T. , Harbison J.P. , Wilkens B.J. 
Published: March 2011

AbstractMolecular dynamics simulations are used to investigate the formation of deep crystalline damage during the low-energy ion bombardment of semiconductor crystals. The trajectories of primary ions are calculated as they propagated through a model crystal lattice. Energy losses by nuclear recoil and and by electronic excitation are included. For beams of heavy ions at energies below 1 keV, the average penetration range of the simulated trajectories is only a few nanometers. However, a small, but, significant fraction of the ions are found to scatter into <011= axial channels through which they propagate tens of nm below the surface. This effect is used to explain high-resolution secondary ion mass spectrometry and photoluminescence data which reveal deep ion penetration and optical damage on the same length scale. Our results suggest that unintentional ion channeling is a major factor in the extensive degradation of optical and electrical properties of semiconductor surfaces which are exposed to low energy ion bombardment during device fabrication.
Influence of Energy Deposited by Energetic Particle Bombardment on thin Film Characteristics
Authors: Winters Harold F. , Eckstein W. , Coufal H.J. 
Published: March 2011

AbstractIt has been recognized since the 1960's that bombardment of a growing thin film by energetic particles strongly influences film properties. Particle bombardment has generally been accomplished by accelerating ions into the growing film. However, it has also been recognized since the 1960's that energetic particles reflected from the target influence the characteristics of films grown by physical sputtering and many experiments have been interpreted on this basis. A systematic study of the energy reflected from the surface by normally incident, singly charged noble-gas ions on five substrates of different masses has recently been published. This data along with sputter yields from the literature allow estimates to be made which were previously unavailable. The energy reflected from the target is carried away by electrons, sputtered particles and reflected ions (neutrals). The purpose of this paper is to provide basic information which will allow thin film scientists to estimate the influence of various experimental parameters on the amount of energy arriving at the growing film. The energy reflected from the target per sputtered atom will be given as a function of ion mass, target mass, and ion energy. TRIM.SP Monte Carlo calculations will be used to estimate the ratio of the energy carried away by sputtered atoms to that carried away by reflected ions. Calculations will also be used to estimate the average energy of the sputtered atoms as a function of ion mass, substrate mass and ion energy. It will be shown how this information can be used to guide the adjustment of experimental parameters in sputtering environments so as to control film characteristics.
Laser-Induced Dry Etching of GaAs with High Aspect Ratio
Authors: Lee Cheon , Sayama Hirokazu , Namba Susumu , Takai Mikio 
Published: March 2011

AbstractLaser-induced thermochemical reactions have been investigated for GaAs in a CCl2F2 gas ambient using an argon-ion laser. The chemical compositions of the reaction products deposited on the etched groove were measured by Auger electron spectroscopy (AES). The conditions of laser power, scan speed, and CC12F2 gas pressure under which the etching reaction occurs without deposition of the residue were clarified. High etching rates up to 267 μm/s and an aspect ratio of 4.5 have been achieved by a single scan of a laser beam. Microprobe photoluminescence and Raman scattering measurement were carried out on the etched surface to characterize damage induced by this processing.
In Situ Observation of Growing Process of Particles in Silane Plasmas and Their Effects on Amorphous Silicon Deposition
Authors: Shiratani Masaharu , Watanabe Yukio 
Published: March 2011

AbstractIn rf silane plasmas, growing process and behavior of dust particles and presence of negative ions are studied by square-wave-amplitude-modulating an rf discharge voltage. By combining the rf modulation method with Mie scattering methods, particle behavior together with temporal evolutions of particle size and density is revealed. While the rf modulation is effective for the suppression of particle growth, small particles are found to exist still in the discharge space for a larger duty cycle. Further, particles seem to be suspended around an rf electrode by counter balance between an electrostatic force due to time-averaged sheath electric field and a force increasing with particle size. The development of particle growth also affects the rf discharge itself, resulting in inhomogeneity of film properties. Negative ion detection is carried out as a first step for studying whether they cause the particle formation. It is found that negative ions are formed in rf silane discharges even for a low concentration of 0.5%SiH4 and their formation is due to attachment to dissociated radicals rather than dissociative attachment of SiH4.
Growth Mechanism and Film Properties in Pulsed Laser-Plasma Deposition
Authors: Metev S. , Meteva K. 
Published: March 2011

AbstractIn the paper the results of a theoretical investigation of the growth process of laser-plasma deposited thin films are discussed. A kinetic approach has been used to establish direct relation between experimental conditions (laser flux density, substrate temperature) and film properties (thickness, structure). The results of some experimental investigations of the deposition process are presented confirming the general conclusions of the developed theoretical model.