bluuebunny/crossref_metadata_2025_split huggingface dataset:
Point defect Production, Geometry and Stability in Silicon: a Molecular Dynamics Simulation Study
Authors: Caturla M.-J. , De La Rubia T. Diaz , Gilmer G.H. 
Published: March 2011

ABSTRACTWe present results of molecular dynamics computer simulation studies of the threshold energy for point defect production in silicon. We employ computational cells with 8000 atoms at ambient temperature of 10 K that interact via the Stillinger-Weber potential. Our simulations address the orientation dependence of the defect production threshold as well as the structure and stability of the resulting vacancy-interstitial pairs. Near the <111> directions, a vacancy-tetrahedral-interstitial pair is produced for 25 eV recoils. However, at 30 eV recoil energy, the resulting interstitial is found to be the <110> split dumbbell configuration. This Frenkel pair configuration is lower in energy than the former by 1.2 eV. Moreover, upon warming of the sample from 10 K the tetrahedral interstitial converts to a <110> split before finally recombining with the vacancy. Along <100> directions, a vacancy-<110> split interstitial configuration is found at the threshold energy of 22 eV. Near <110> directions, a wide variety of closed replacement chains are found to occur for recoil energies up to 45 eV. At 45 eV, the low energy vacancy-<110> split configuration is found. At 300 K, the results are similar. We provide details on the atomic structure and relaxations near these defects as well as on their mobilities.
Ion Implantation Damage and Annealing in GaSb
Authors: Iyer S. , Parakkat R. , Patnaik B. , Parikh N. , Hegde S. 
Published: March 2011

ABSTRACTIon implantation technique is being investigated as an alternate technique for doping GaSb. Hence an understanding of the production and removal of the damage is essential. In this paper, we report on the damages produced by implantation of Te, Er, Hg and Pb ions into undoped (100) GaSb single crystals and their recovery by Rutherford backscattering (RBS)/channeling. The implantations of 1013 to 1013 ions/cm2 in GaSb were done at liquid nitrogen temperature at energies corresponding to the same projected range of 447Å. A comparison of the damage produced by the different ions and their recovery was made by RBS/channeling along <100> axis of GaSb. Near surface damage equivalent to that of an amorphous layer was observed even at lower doses. Upon annealing at 600°C for 30 sec., the Te implanted samples showed best recovery compared to others (Xmin = 11%), the value of Xmin being better than those normally observed in unimplanted Te-doped substrates.
Suppression of Thermal Grain Growth in Nickel by Prior Electron Irradiation
Authors: Gao Yuzun , Allen Charles W. , Bitrtcher R. C. 
Published: March 2011

ABSTRACTAn anomalous effect of electron irradiation on thermal grain growth in Ni has been observed using in situ TEM. Grain growth during thermal annealing was suppressed in areas irradiated with electrons. Grain growth suppression required a minimum electron energy between 100 and 200 keV. This alteration of thermal grain growth is attributed to electron beam injection of a surface contaminant such as carbon. This work points out that care must be exercised in the execution and evaluation of in situ TEM or ion beam experiments that deal with microstructural changes which are highly compositionally sensitive.
A Critical Regime for Amorphization of Ion Implanted Silicon
Authors: Goldberg R. D. , Williams J. S. , Elliman R. G. 
Published: March 2011

ABSTRACTA critical regime has been identified for ion implanted silicon where only slight changes in temperature can dramatically affect the levels of residual damage. In this regime decreases of only 5° C are sufficient to induce a crystalline-to-amorphous transformation in material which only exhibited the build-up of extended defects at higher temperatures. Traditional models of damage accumulation and amorphization have proven inapplicable to this regime which exists whenever dynamic defect annealing and damage production are closely balanced. Irradiating ion flux, mass and fluence have all been shown to influence the temperature— which varies over a range of 300° C for ion species ranging from C to Xe—at which the anomalous behaviour occurs. The influence of ion fluence suggests that complex defect accumulation plays an important role in amorphization. Results are presented which further suggest that the process is nucleation limited in this critical regime.
Modulation Wavelength Dependence of Ion Mdong in Metallic Superlattices
Authors: Alexander Dale E. , Fullerton Eric E. , Baldo P.M. , Sowers C.H. , Rehn L. E. 
Published: March 2011

ABSTRACTIon mixing was studied in polycrystalline Nb/V and single-crystal Mo/V superlattices and in bilayers of the same materials. Systematic variation in the modulation wavelength, Λ, revealed a factor of three decrease in mixing efficiency at small Λ for Nb/V. The decrease appears to coincide with a structural transition in which the Nb/V superlattices become coherent. The results are consistent with a diffusion-induced grain boundary migration interpretation of mixing during irradiation.
Metastable Crystalline Phases Synthesized by Ion Beam Mixing in Some Nb-Based Binary Metal Systems
Authors: Liu B.X. , Zhang Z.J. 
Published: March 2011

ABSTRACTIn the Nb-rich Nb-Fe(Co,Ni) multilayered films, two metastable crystalline (MX) phases of hep and fee structures were formed by room temperature 200 keV xenon ion mixing. The phase formation was through a two-step transition, Le. a first shearing of bcc—>hcp and then a sliding of hep—>fcc. The free energy curves of the observed MX phases were calculated and included into the free energy diagram together with those of the terminal solid solutions, the amorphous phase and the equilibrium intermetaШc compounds. An independent comparative thermal annealing experiment was conducted with the corresponding as-deposited multilayers and the results certified the emerging sequence of the MX phases being exactly the same as the calculated diagram predicted. Moreover, a crystallographic model was figured out for the bec—>hcp—>fcc transition and the resultant lattice parameters agreed well with the experimental ones.
Ion Implantation Doping of Semi-Insulating Polycrystalline Silicon
Authors: Lombardo Salvatore , Campisano S. U. 
Published: March 2011

ABSTRACTThe study of doping of silicon nano-grains in semi-insulating polycrystalline silicon is of paramount importance since intense room-temperature luminescence at 1.54 µm has been demonstrated in this silicon-based semiconductor when doped with erbium ions. We have investigated the formation of p- and n-type layers of semi-insulating polycrystalline silicon by implantation and diffusion of B, P, As, and Er. The room-temperature resistivity can be changed by more than six orders of magnitude for both p- and n-type doping. A dramatic decrease of resistivity is observed for dopant concentrations above a threshold level; this effect is explained by assuming that the free-carrier motion is limited by grain boundary barriers and the electrical conduction is due to thermionic emission and tunneling of the carriers through the barriers. The prevalence of one mechanism over the other depends upon temperature, oxygen concentration and doping. In the undoped material the barrier height is large (≈ 0.5 eV), but for dopant concentrations above the threshold, it decreases with the doping level. Correspondingly, the conductivity increases by many orders of magnitude. The determination of the threshold value allows the evaluation of donor and acceptor grain boundary trap densities. Diodes have been fabricated by implantation and diffusion of boron and erbium. The I-V characteristics of these diodes are interpreted on the basis of the material modeling.
The Effect of Mass Resolution During Ion Implantation on Defect Formation and Electrical Properties in Gallium Arsenide.
Authors: Jasper Craig , Klingbeil Scott , Jones K.S. , Robinson H.G. 
Published: March 2011

ABSTRACTControl of threshold voltage during gallium arsenide (GaAs) Metal Semiconductor Field Effect Transistor (MESFET) processing is critical. Channel formation typically is done using ion implantation of 29Si+ from a SiF4 source. The use of Si+ presents a variety of potential cross-contamination problems. 28Si+ and 30Si+ beams can become contaminated with 28N2+, 28CO+, and 30NO+. While 29Si+ is relatively pure, the abundance of 29Si+ in the mass spectrum is 4.67%, thus reducing the potential beam current. This study investigates the effects of varying the mass resolving power of an Eaton 6200AV implanter on the electrical parameters and defect formation. The mass resolving power was adjusted by changing the mean path size through the slit of the aperture opening and magnetic separator current. Electrical device characterization measured a small shift in saturated source-drain current (Idss) and break down voltage, while threshold voltage shifts of approximately 80 mV were observed, with the various mass resolution powers. Transmission Electron Microscopy (TEM) showed that there is minimal change in the extended defect density with changes in isotope and aperture opening. Secondary Ion Mass Spectrometry (SIMS) measured the amount of cross contamination and these results correlated well with the observed changes in device electrical properties.
Discharge-Pumped VUV F2 Molecular Laser Annealing of Heavily Se+-Implanted GaAs
Authors: Shibata Hajime , Makita Yunosuke , Yamada Kawakatsu , Uchida Yutaka , Satoh Sabro 
Published: March 2011

ABSTRACTThe capability of discharge-pumped vacuum ultraviolet F2 molecular laser for laser annealing of heavily ion implanted semiconductor was demonstrated for the first time using Se+ heavily ion implanted GaAs. Cr-doped semi-insulationg GaAs wafers were used as the substrates, and the Se+ implantation energy and dose were controlled to 100 keV and 1× 1015 cm-2, respectively. Samples were annealed using a F2 molecular laser ( wavelength = 157 nm ) with a single pulse ( width ~ 20 ns ) in the energy density range from 200 to 800 mJ/cm2 in a nitrogen atmosphere. In addition, furnace annealing was done on separate samples at 850 ºC for 20 minutes in a purified hydrogen atmosphere for comparison. Characterization of the samples was carried out using Raman scattering and ellipsometry. The laser annealed samples exhibited intense Raman scattering LO phonon peaks whose intensity increased with increasing laser power density, whereas the furnace annealed samples exhibited a very weak LO phonon peak. It was demonstrated for the first time that VUV photons can be very effective in annealing ion implantation damage as compared with conventional furnace annealing. The behavior of Raman scattering spectra as a function of laser energy density was explained quantitatively by a “spatial correlation” model. The model made it possible to estimate the average size of the recovered crystal regions in samples for any given laser energy density.
Optical and Structural Properties of MeV Erbium Implanted LiNbO3
Authors: Fleuster M. , Buchal CH. , Snoeks E. , Polman A. 
Published: March 2011

ABSTRACTLiNbO3 single crystals were implanted with Er ions at 3.5 MeV with fluences up to 3*1016 Er/cm2 and subsequently annealed at 1060°C. The warm-up rate of the sample determines whether the implanted, amorphized surface layer recrystallizes via columnar or via layer-by-layer solid phase epitaxial (SPE) growth. The maximum concentration of optically active Er ions is determined to be 0.18 at.%.
Ion-Implanted Thin Film Phosphors for Full-Color Field Emission Displays
Authors: Kalkhoran Nader M. , Maruska H. Paul , Namavar Fereydoon 
Published: March 2011

ABSTRACTWe have investigated the application of ion implantation technique for introducing activator and co-activator ions into host materials such as ZnS and Zn2SiO4, and have produced phosphors with differing emission peaks throughout the visible range. A number of different ions including, Mn+, Al+ and rare-earth metals have been implanted. Zn2SiO4:Mn showed bright yellow cathodoluminescence. We have demonstrated that by varying the parameters for ion implantation and annealing, a single ZnS sample with emission peaks ranging from violet to yellow can be produced; i.e, chromaticity engineering. In one case, our results indicated that photoluminescence (PL) spectrum of ZnS phosphors shifts from blue to green by increasing the dose of implanted A+ ions. The Al+-implanted ZnS samples showed emission peaks shifting from 440 to 510 nm when the aluminum dose was raised from 1 × 1015 to 1 × 1017 A1+/cm2. Therefore, by activating color centers in thin film phosphors using ion implantation, efficient and low-cost full-color field emission displays can be fabricated on a single layer of host material.
Ion Implantation into High-Speed Steel for Improved Tribology
Authors: Hirvonen J-P. , Rück D. , Yan S. , Lappalainen R. , Torri P. 
Published: March 2011

ABSTRACTIon implantation into steels with a martensitic microstracture is reviewed and discussed in terms of different implanted species and observed changes in the structure. Both single ion and dual ion implantation treatment are included. The disability of the nitrogen ion implantation to improve the tribological characteristics of steels with a martensitic microstructure can be overcome by dual implantation of titanium and carbon, for example. Results of tribological tests on samples in which titanium is replaced by chromium are more controversial, although changes in the sliding characteristics were observed. Dry sliding on the samples implanted up to 1018 ions/cm2 is totally different by nature and -based on the reported results- associated with the formation of carbon precipitates on the surface. The thermal stability of implanted nitrogen and carbon in MЗ high-speed steel was examined and nitrogen was shown to be less stable than carbon. Mechanical and tribological properties were further changed by heat treatment after ion implantation, which indicates that temperature is also a critical parameter during ion implantation.
Tribomechanical Property Modification of Commercial TiN Coatings by Carbon Ion Implantation
Authors: Liu L.J. , Sood D.K. , Manory R.R. 
Published: March 2011

ABSTRACTAbout 2 μm thick commercial coatings of TiN on high speed steel substrates were implanted at room temperature with 95 keV carbon to nominal doses between 1 × 1017 and 8×1017 ions cm-2. An ultra-microhardness apparatus (UMIS-2000) was used to measure hardness, and a pin-on-disc machine (CSEM Tribometer) with a sapphire ball was used to measure wear, friction and adhesion. Carbon implantation induced a significant improvement in ultra-microhardness, friction coefficient and wear properties. The surface microhardness increases monotonically by up to 115% until a critical dose φ crit is reached. Beyond this dose the hardness decreases, but remains higher than that of unimplanted sample. A lower friction coefficient and a longer transition period towards a steady state condition were obtained by implantation. An improvement of up to four times in the wear is obtained after carbon implantation. Topology studies with SEM show a change in the mode of wear. The changes in tribomechanical properties are discussed in terms of radiation damage and possible second phase formation.
Reduction of Defect Fluxes Using Dual-Ion-Beam Processing
Authors: Iwase A. , Rehn L. E. , Baldo P. M. , Okamoto P. R. , Wiedersich H. , Funk L. 
Published: March 2011

ABSTRACTRadiation-induced segregation (RIS) in Ni-12.7% Si and Cu-1% Au alloys was studied using Rutherford backscattering spectroscopy during He and Ne irradiation at elevated temperatures. During single ion-beam irradiation with 1.5 MeV He, strong RIS of Si toward the surface was observed in Ni-12.7% Si. Simultaneous irradiation with 400 keV Ne and 1.5 MeV He almost completely suppressed the Si segregation, even when the calculated damage production rate by Ne was only a few percent of that by He ions. A similar effect of dual-beam irradiation was observed in the Cu-1% Au alloy, i.e., the rate of near surface Au depletion was strongly reduced under simultaneous irradiation. The present result shows that dual-beam irradiation can be applied to control RIS and RED (Radiation Enhanced Diffusion) during ion beam processing.
Surface Modification of Electromagnetic Railgun Components
Authors: Otooni M. A. , Graf A. , Dunham C. , Brown Ian , Yao Xiang 
Published: March 2011

ABSTRACTCopper and aluminum used for rail and armature materials in electromagnetic railgun systems undergo severe degradation during the EM gun operation. The extent of this degradation is especially severe in guns operated at high energy levels or designed for repeated firings. In an effort to improve surface properties of the copper rail, armature, and sabot materials, the technique of metal ion implantation using a vacuum arc ion source has been employed. Preliminary tests have been conducted to identify the best implant species to improve spark erosion resistance, scratch resistance and hardness. The implanted species included Al, Ti, Cr, Ni, Ta, Ag, and W. The implantation energy range and dose varied between 100–180 KeV and 0.4 to 2 × 1017 cm-2, respectively . Several analytical techniques were also used to assess the effect of implanted species. These included Rutherford Back Scattering (RBS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Microhardness Measurements, Spark Erosion and Scratch Testing. It has been tentatively concluded that Ta and Ni implantation of the copper rail substantially improve wear and inhibit arc erosion. There is also sufficient evidence to indicate that implantation of the aluminum armature with Cr and Ta, involving two stages of implantation, will also improve its mechanical and wear properties.
Ion Implantation Distribution Study in Biological Samples
Authors: Lu Ting , zhu Fengsui , Zhou Shanyuan 
Published: March 2011

ABSTRACTThe organic materials of biological samples such as wheat, rice, corn and bean were implanted by nitrogen irons with energy ranging from 35–180 KeV. Biological effects including physiological and genetic variations on these crops were induced by ion implantation. In order to understand the role played by ion implantation, the distributions and the ranges of the implanted ions in biological samples were measured by RBS spectrometry. Theoretical calculations of the ranges were carried out using TRIM program. The results of experimental measurement were found essentially the same as the calculated values. The mechanism of the biological variations induced by ion beams is discussed.
Effect of Ion-beam Radiation on the Anisotropy of Resistivity in YBa2Cu3O7-δ Thin Films
Authors: Wu J. Z. , Zhang Z. H. , Chen V. W. , Yu N. , Chu W. K. 
Published: March 2011

ABSTRACTDifferent behaviors of the normal-state resistivity have been observed in (110)-, (113)- and a-oriented YBa2Cu3O7-δ thin films under 200 keV H+ irradiation. It suggests that the c-axis electrical conduction is very sensitive to nonoxygen point defects and a ”semiconductor-metal” phase transition could be induced at very low densities of these defects.
A More Efficient Approach for Monte Carlo Simulation of Deeply-Channeled Implanted Profiles in Single-Crystal Silicon
Authors: Yang Shyh-Horng , Lim David , Morris Steven J. , Tasch AL F. 
Published: March 2011

ABSTRACTIn this paper is reported a new approach for the Monte Carlo simulation of deeply-channeled implanted profiles in single-crystal silicon which has greatly improved efficiency. This approach has been successfully implemented in the UT Monte Carlo code (UT-MARLOWE). A time savings of up to 212X has been observed with a 4-stage simulation. A simulation of arsenic implants with 15 keV implant energy typically takes about 12 minutes on a workstation.
High Resolution Triple Axis Diffractometry in Indium-Carbon and Gallium-Carbon Co-implanted Gallium Arsenide
Authors: Horng S.T. , Madok J.H. , Haegel N.M. , Goorsky M.S. 
Published: March 2011

ABSTRACTHigh-resolution x-ray triple axis diffractometry was used to characterize damage recovery in gallium arsenide implanted with gallium or indium ions, and co-implanted with carbon ions. From reciprocal space mapping around the (004) reciprocal lattice point, the evolution of residual strain and the lattice plane tilt induced by the ion implantation and annealing processes were analyzed. The lattice damage in implanted gallium arsenide is dependent on the dose and ion type; annealing subsequently alters the structural properties of the material. For example, In/C co-implanted gallium arsenide shows a greater amount of residual damage as compared to Ga/C co-implanted gallium arsenide after rapid thermal annealing at 885 °C for 5 seconds. For a given Group III ion / C co-implant, we observe the highest p-type activation when the Group III ion and C implant doses are the same. Increasing the Group III ion dose reduces the material quality and has a concomitant negative effect on the electrical properties of the material. These results suggest that reciprocal space maps can provide insight into the relationship between the structure and properties of implanted compound semiconductors.
Channeling in LiNbO3 :Fe Modulated by Holographic Stress Field Superlattice
Authors: Kukhtarev N. , Kukhtareva T. , Ila D. , Williams E. K. , Zimmerman R. L. , Caulfield H. J. 
Published: March 2011

ABSTRACTPhoton and proton channeling have been observed in LiNbO3:Fe crystals which have holographically recorded electric field gratings. An analogy between photon and proton channeling is developed and compared with the experimental results.
Crystallographic Structure of Mesotaxial IrSi3 in Si
Authors: Hinneberg H.-J. , Sjoreen T. P. , Chisholm M. F. 
Published: March 2011

ABSTRACTA buried epitaxial IrSi3 layer has been produced in (111) oriented Si by high dose Ir+-implantation (1 MeV, 1.7×1017 Ir+/cm2, 550°C) and subsequent annealing (5 h at 1100°C). Transmission electron microscopy and ion channeling show that the hexagonal IrSi3 prefers to form with its (2110) plane oriented parallel to Si(111), while its [0001] direction is parallel to either [112], [121], or [211]. Thus, the IrSi3 film is made up of three differently oriented crystals, each occupying about 1/3 of the suicide volume.A dose of 3.5×1016 Ir+/cm2 leads to the formation of a band of large, isolated precipitates. They have the same epitaxial relationship to Si, but the Si(111) plane is no longer the only one to which the (2110) of IrSi3 is parallel. Instead precipitates are also observed oriented parallel to (111), (111), and (111) in Si in roughly equal numbers. Consequently, there are now 12 possible orientations of IrSi3 crystals. We assume that strain relief and interface area minimization are the main factors suppressing the additional orientations in the continuous IrSi3 films formed by the coalescence of precipitates at higher doses.
Si Ion Implantation for Secondary Defect Reduction in Simox Material
Authors: Ellingboe S.L. , Ridgway M.C. 
Published: March 2011

ABSTRACTA novel methodology for altering the amount and/or nature of post-anneal disorder in SIMOX substrates has been investigated. A pre-anneal, secondary Si-ion implant (with an ion range less than that of the primary O-ion implant) is shown to effectively getter Si interstitials to the near-surface region during annealing. As a consequence, post-anneal disorder at the front. Si/SiO2 interface is significantly reduced. Alternatively, a Si-ion implant with an ion range greater than that of the O-ion implant can alter the post-anneal disorder at the back Si/SiO2 interface.