bluuebunny/crossref_metadata_2025_split huggingface dataset:
Powder Technological Vitrification of High Level Nuclear Waste by In-Can Hot Pressing Including a Sol-Gel Route
Authors: Caneiro A. , Ondracek G. , E.H. Toscano 
Published: March 2011

AbstractPowder technology is used to immobilize high level nuclear waste (HLW) in sintered borosilicate glass. By uniaxial in-can hot pressing(temperature 950 K; pressure 1 MPa; heating rate ∼100 K/h; cooling rate 5 K/h), glass products containing simulated HLW(15 wt.%) have been produced in stackable steel cans (≤ 200 mm diameter). High densities, bulk integrities and homogeneities for the waste element distribution are realized. The advantages of powder technology are for example: (i) no segregation due to solid state vitrification, (ii) low evaporation losses and no compatibility problems due to low densification temperatures (sinter temperature ∼0.6 softening temperature of glass), (iii) production in easily arrangeable and interchangeable stacking units at modest pressures adequate especially for the use in hot cells under remote handling conditions, (iv) choosing units with alternatively HLWo r MLWin prescribed sequences to control the heat production of the package. As demonstrated now, the process is appropriate for high level waste (HLW), medium level waste (MLW) and mixed (HLW/ MLW vitrification, and is insensitive to waste modifications.As the next step the effect of glass modifications was studied. In order to improve the glass leaching resistance and maintain low viscosity, silicon dioxide was doped with titanium dioxide. The mixture (referring to eutectic composition) was produced by a sol gel route and combined finally with 15 w/o HLW-oxides. Hot pressing of the obtained gels at 1273 K and 20 MPa provided highly homogeneous products with high densities.
Iodine Waste Forms: Calcium Aluminate Hydrate Analogues
Authors: Brown Dale R. , Grutzeck Michael W. 
Published: March 2011

AbstractPhase relations in the system 3CaO·AI2O3-CaSO4-CaI2-H2O in equilibrium with excess water were established by means of room temperature bottle hydration of various bulk chemistries in the system. Starting with end members ettringite (3CaO·Al2O3·3CaSO4·32H2O) and tetracalcium aluminate monosulfate-12-hydrate (3CaO·Al2O3-CaSO4-12H2O), iodine-substituted analogue phases were synthesized which containe increasingly greater percentages of iodine. The iodine-substituted ettringite was found to be unstable whereas the iodine-substituted monosulfate formed readily. SEM, wet chemistry, IR, and x-ray diffraction characterization of the latter phase suggest that its formula is 3CaO·Al2O3·Ca(IO3)2·2H2O. Cement pellets containing this “Afm” iodine-substituted phase were subjected to a modified MCC-1 static leach test. Although the normalized iodine leach rate was relatively high when compared with AgI encapsulated in portland Type III cement, this same leach rate was approximately equal to the rates that have been reported for Ba(IO3)2, Ca(IO3)2, and Hg(IO3)2 in portland cement. The normalized iodine leach rate obtained also was found to be roughly comparable to that given for I-sodalite in cement. Diffusion is indicated as the primary leach mechanism, becoming dominant after the first three days of leaching.
Cementitious Mixtures for Sealing Access Shafts/Boreholes Through Evaporite and Clastic Rocks in a Radioactive-Waste Repository
Authors: Wakeley Lillian D. , Roy Della M. , Grutzeck M. W. 
Published: March 2011

AbstractGeochemically compatible cement-based mixtures were designed for sealing a potential geologic repository for high-level radioactive waste in evaporite and related rock strata. The slightly expansive cementitious mixtures were based on Class H cement and Class C fly ash, with silica and calcium sulfate additives, and a low ratio of water to cementitious solids (w/s = 0.32). Both a salt-free and a salt-containing version were used in tests with anhydrite/siltstone and halite.Although it is difficult to achieve strong bonding between anhydrite and cement-based mixtures, tensile bond strengths, interface permeability, and other properties of the composites as a whole indicate achievement of the desired chemical and physical compatibility between these materials Integrity of bonding and low permeability to water (on the order of 110 darcy) suggest the likelihood of attaining durable sealing of repository access shafts/boreholes through the use of such chemically tailored cementitious mixtures.Rock samples used in ongoing sealing studies were obtained from various areas throughout the United States. The data in the present paper represent results for rocks obtained from the Palo Duro Basin and as such typify bedded-salt strata.
Characterization of Doped Si-TiSi2Bilayers Formed by Ion Beam Mixing and Rapid Thermal Annealing
Authors: Maex K. , de Keersmaecker R.F. , Alkemade P.F.A. 
Published: March 2011

ABSTRACTThe use of rapid thermal processing is reported for simultaneous formation of TiSi2from Ti deposited layers and activation of As or Sb implanted profiles in Si. Properties of the silicide and the doped Si are reported with emphasis on impurity redistribution and defect removal.
Moving Species in Pt2Si, Ni2Si and CrSi2 Formed by Ion Mixing and Thermal Annealing
Authors: Zhao X. A. , Affolter K. , Nicolet M-A. 
Published: March 2011

ABSTRACTWe have determined the dominant moving species during the formation of CrSi2, Ni2Si, and Pt2Si by irradiating with 600 keV Xe ions thin bilayers of evaporated metal on silicon and silicon on metal above room temperature. Two very thin markers were placed at the metal-silicon interface and at the bottom interface with the Si02 substrate. The separation of the two markers as a function of the amount of silicide formed by either ion mixing or thermal annealing was monitored by backscattering spectrometry. This experiment identifies the dominant moving species. The results establish that the moving species for ion mixing and for thermal annealing are the same in CrSi2, but not in Ni2Si and Pt2Si.
Electrical Characterization of Ion Imiplanted, Thermally Annealed TiN Films Acting as Diffusion Barriers on Shallow Junction Silicon Devices
Authors: Armigliato A. , Finetti M. , Gabilli E. , Guerri S. , Ostoja P. , Sabato G. , Scorzoni A. 
Published: March 2011

ABSTRACTTiN films prepared by implantation onto evaporated Ti layers are tested as diffusion barriers in contact with a thick Al overlayer. Both the TiN/Al and TiSi2/TiN/Al contact structures are evaluated, after thermal treatments up to 600 C, on shallow junction diodes and four terminal resistor test patterns for contact resistance measurements. It is shown that, upon annealing at 600 C, the TiSi2/TiN/Al contact system still exhibits excellent electrical performances. The degradation is found to depend on TiSi2 thickness and contact area.
Modification of Electronic Transport in Polymer and Carbon Films by High and Low Energy Ion Irradiation
Authors: Venkatesan T. , Levi R. , Banwell T. C. , Tombrello T. , Nicolet M. , Hamm R. , Meixner A. E. 
Published: March 2011

ABSTRACTWe have explored the origin of the ion-induced conductivity in polymer films and the distinction between low energy ion-implantation and high-energy ion irradiation. In experiments involving irradiation of polymer and carbon films with ions of energy from 200 keV to 25 MeV we have established that with both low and high energy ions the polymers undergo carbonization. However, the saturation resistivity obtained with low energy implantation is four to six orders of magnitude larger than those obtained by high energy ion irradiation. In experiments on irradiation of carbon films low energy ions caused a two orders of magnitude increase in the resistivity while high energy ion caused a two orders of magnitude decrease. This implies that the structure of the carbonized polymer is different for the low and the high energy ion irradiation. While in the former case there may be no crystalline order in the films; in the latter case, a microcrystalline graphitic structure is obtained (with four orders of magnitude larger conductivity than in the former case). The formation of graphitic crystalline order with increasing high energy ion dose was verified by electron energy loss spectroscopy. This is an interesting example of crystallization induced by electronic excitation alone with no macroscopic thermal effect.
Dose Measurements on Micro- and Submicrometer Implanted Structures using Thermal-Waves
Authors: Smith W. Lee , Reuss Robert H. , Clark William , Rensch David 
Published: March 2011

ABSTRACTThermal-wave measurement techniques have recently been developed for measuring ion implant dose over the range 1E10 to 1E16 ions/cm2. The spatial resolution obtained with this method is 1 µm, an improvement of approximately 3000X over that of other dose monitors. This resolution capability together with the fact that the thermal-wave measurements are noncontact and nondestructive, permit dose measurements to be made on implanted areas (device features) on patterned wafers, as well as on test wafers.A new potential application of the thermal-wave technique is the measurement of dose implanted by focused ion beam (FIB). Since the FIB technique is a high-resolution, direct-write process and since current FIB systems are limited to scan fields of less than 0.5 mm2, a high-resolution probe to monitor dose and uniformity is necessary.In this paper, we report the measurement of ion dose implanted by focused beams into areas of ‹10−2 mm2. Even single FIB-implanted lines of 0.20 µm width have been detected, and programmed lateral dose variations measured. Experimental results demonstrating the potential of this technique are presented.
Chemical Metal Deposition on Insulators by An Ion-Beam Process
Authors: Eskildsen Svend Stensig , SØrensen Gunnar 
Published: March 2011

ABSTRACTAn ion-induced decomposition of thin metal-compound films on insulating surfaces is described. 100-keV ion beams of Ar+, Kr+, and Xe+ was used to decompose thin (~10 nm) films of a palladium compound on polyimide and alumina. Changes in the stoichiometry have been observed with Rutherford Backscattering Spectrometry. The compound was also decomposed in a pattern using a mask, and the nondecomposed film could easily be removed with a suitable solvent. The decomposed palladium compound was used as a catalyst for a direct, electroless metal deposition of Cu. The plating speed was 30 nm/min, and a 4-5 µQcm copper film could be obtained after 3-4 min plating. Plated metal patterns are demonstrated on both polyimide and alumina, with a resolution in the µm range. On polyimide plating of a three-dimensional structure has been demonstrated.
Regrowth of Amorphized Compound Semiconductors
Authors: Opyd W.G. , Gibbons J.F. 
Published: March 2011

ABSTRACTEpitaxial regrowth is investigated for layers of InSb and GaAs amorphized by liquid nitrogen temperature ion implants. Experimental criterion for amorphization and limitation of regrowth are correlated with damage calculated by a Boltzmann transport equation approach to ion implant modeling. Conditions for complete epitaxial regrowth as determined by channeled Rutherford backscattering spectrometry are presented with evaluation of residual defects by transmission electron microscopy. Electrical activation following regrowth of GaAs is reported and correlated with calculated damage profiles.
Tem Structural Studies on Zn+ Implanted and As+ /Zn+ Dually Implanted GaAs
Authors: Morita E. , Kasahara J. , Arai M. , Kawado S. 
Published: March 2011

ABSTRACTMicrodefects in Cr-doped SI LEC (001) GaAs wafers which were implanted with Zn+ or As /Zn and capless-annealed in an As ambient have been studied by means of transmission electron microscopy. Most of the microdefects in Zn +- implanted GaAs specimens were identified as precipitates and stacking fault tetrahedra (SFTs). Every SFT was accompanied by a precipitate at the apex. Most of the precipitates were distributed from Rp to Rp + 2∆Rp. Two types (α and β) of SFTs were differentiated by the arrangement of atoms in the core of the stair-rod partial dislocations bounding the periphery of the SFTs in a polar Frystal. β-SFTs were, however, predominantly formed in Zn+ implanted GaAs specimens. Dual implantation of As+ and Zn+ suppressed the formation of SFTs, but not that of precipitates. The formation of SFTs was found to be influenced by the deviation in stoichiometry.
Rapid Thermal Anneal and Furnace Anneal of Silicon and Beryimlum Implanted Gallium Arsenide
Authors: Yuen A.T. , Long S.I. , Merz J.L. 
Published: March 2011

ABSTRACTA comparison has been made between rapid thermal annealing (RTA) and furnace annealing (FA) of implanted GaAs. Hall measurements showed consistently higher electrical activation of n-type (Si-5E12 cm −2) implants with FA and higher electrical activation of p-type (Be-1E14 cm −2) implants with RTA. Photoluminescence (PL) revealed that for RTA temperatures above 950°C some of the Si was going onto As, acceptor sites, thus reducing the net donor concentration. PL for RTA below 950°C showed signs of incomplete recrystallization. By a technique of “dual implantation” of As and Si into GaAs we were able to force the Si onto Ga-sites resulting in a higher donor concentration after RTA.
Correlation of Rutherford Backscattering and Electrical Measurements on Si Implanted InP Following Rapid Thermal and Furnace Annealing
Authors: Bahir G. , Merz J.L. , Abelson J.R. , Sigmon T.W. 
Published: March 2011

ABSTRACTWe report on the structural and electrical properties of (100) InP resulting from the implantation of 180 keV Si+ and subsequent annealing. The radiation damage produced by implantation at substrate temperatures from 77 to 480 K is evaluated using MeV He ion channeling. Varying degrees of recrystallization are found depending on the implant temperature and choice of furnace vs. rapid thermal annealing. Samples implanted at 25°C to a dose of 3.3.1014ions/cm2 continue to display structural disorder regardless of annealing procedures. In contrast, implantation at 200°C to 3.3-1014ions/cm2 produces a low but measurable damage level. Further annealing lowered the disorder to a level similar to that of unimplanted material.The electrical activation of both low and high fluence ion doses is nearly the same at the optimal conditions for rapid thermal annealing (RTA) or furnace annealing (FA). However the electron mobility is found to be higher after hot implantation and RTA. The electrical profile after hot implantation is wider than the profile after RT implants and FA.
Buried Oxide in Silicon by Oxygen Implantation Into Scanned Wafers
Authors: Mogro-Campero A. , Love R.P. , Lewis N. , Hall E.L. , McConnell M.D. 
Published: March 2011

ABSTRACTA single crystal silicon layer on an insulator is a desirable structure for applications in electronics. One of the leading processes for achieving such a structure is the formation of a buried oxide layer in silicon by heavy dose oxygen implantation. Characteristics of this material have been reported for implantation by beam scanning. In this work we report on material prepared by wafer scanning at rates such that significant temperature cycling occurs during implantation, and we use TEM and Auger analysis to investigate the differences between these samples and others prepared by the conventional technique of beam scanning. For the implantation and annealing conditions used here, we find more oxygen in the top silicon layer in the case of wafer scanning, and the oxygen concentration increases after annealing at 1150°C for 2 hours, leading to a structure of precipitates throughout the single crystal top silicon layer. For beam scanning, the oxygen concentration decreases after annealing and achieves background levels near the surface, leading to a zone which is free of precipitates.
On The Formation of Si Oxide by Ion Implantation
Authors: Namavar F. , Budnick J.I. , Sanchez F.H. , Hayden H.C. 
Published: March 2011

ABSTRACTOxygen 0+ ions have been implanted into Si both at room temperature and liquid nitrogen temperature in order to determine the effect of implantation temperature on SiO2 formation. Samples were analysed by RBS with 1.5 MeV He+ ions. The implants of 0+ in Si were done at 150 keV with current densities of ≤10 μA/cm2. For doses of more than 1.5×1018 0+/cm2, in-situ RBS experiments positively indicate a 2:1 oxygen silicon ratio. Increased 0+ doses (for both room temperature and liquid nitrogen temperature) cause the Si02 layers to spread uniformly and symmetrically toward both the surface and the interior. From these results, it is apparent that excess oxygen diffuses toward Si/Si02 interfaces in our experimental situation even at liquid nitrogen temperature.
Defect Structure at Buried Silicon Nitride Layers
Authors: Kaat E.H. Te , Belz J. 
Published: March 2011

ABSTRACTBuried insulating silicon nitride layers are formed by a 400°C N+-implantation at 150 keV with fluences from 0.35 to 1×1018 N+/cm2 and subsequent anneal at 1200°C in dry nitrogen. TEM and AES measurements on bevelled samples yield a correlation of ion and damage profiles to local defect structures. Low dose implantation results in polycrystalline precipitates of scaled spherulitic structure. High dose continuous polycrystalline nitride layers have good insulation properties following a 5 hour anneal. During anneal, the common asymmetrical ion depth profile transforms to a nearly rectangular profile. The silicon surface layer contains 106 to 108 dislocations/cm2, which seem to be passivated, since detrimental effects on electronic devices have not been measured.
Some Recent Developments in Industrial Ion Implanters
Authors: Ryding Geoff 
Published: March 2011

ABSTRACTsemiconductor doping. This paper surveys some of the equipment developed at Eaton Corporation in response to the proliferation of ion implanted devices. Developments in both high current (~10mA) and medium current (~1mA) implanters will be discussed.The evolution of dedicated equipment for the production of buried oxide layers (silicon on insulator technology) will also be reviewed.
The Channeling of Ions Near the Silicon 〈001〉 Axis
Authors: Ziegler J. F. , Lever R. F. 
Published: March 2011

ABSTRACTThe first experimental mapping of the ion beam channels near the Si 〈001〉 axis is reported. Remarkably fine structure is observed, with over thirty microchannels identified within 20 degrees of the Si 〈001〉 axis. Each map is made from about 16000 channeling spectra with each channeling probability becoming a pixel of information in the final plot. Contour maps have been constructed for ions of He and N with energies from 50 to 2000 keV. All features are identified by theoretical plots of silicon planar channels and axial channels.
Effect of Preamorphization Depth on Channeling Tails in B+ and As+ Implanted Silicon
Authors: Suni I. , Rqnkainen H. , Eranen S. , Murto T. , Krontiras Ch. , Finetti M. 
Published: March 2011

ABSTRACTWe have studied the effects of ion-channeling in B+ and As+ implanted Si which has been preamorphized to different depths by 28 Si+ irradiation at 60 keV and 180 keV. It is shown that the junctions for incompletely amorphized substrates are only slightly deeper than predicted by LSS theory. For preamorphized layers extending beyofnd-the predicted junction depths the implantations of 25 keV B+ and 120 keV 75As+ with a dose of 5-1015 cm-2 yield junction depths in the order of 2200 - 2300 Å after furnace annealing at 700°C for 30 minutes.
Electro-Optical Characteristics of Shallow Silicon Junctions Fabricated Through Masked Ion Implantation
Authors: Silard Andrei P. 
Published: March 2011

ABSTRACTThe work presents the main electro-optical characteristics of very shallow silicon n+-p and P+-n junctions fabricated through masked ion implantation of phosphorus (31P+) and boron (11B+), respectively. The dependence of electro-optical characteristics on technological parameters (implant energy E and dose Q, oxide thickness Xox, impurity redistributions, etc.) are outlined in detail.The implant step was performed through a thermally-grown silicon dioxide (SiO2) mask of variable thickness (Xox = 100-1200 Å) at energies ranging from E=10 keV to 50 keV and with a dose level Q = 5 x 1014 - 2 x 1015 cm-2. As a rule, after the implant step the oxide layer was etched down. In several samples, the Si0 2 layer was preserved in the finished devices.The characterization of fabricated junctions was performed using a Karl Zeiss quartz prism monochromator coupled to a Tektronix 31/4661 data acquisition system. The main peculiar results could be summarized as follows: (a) all fabricated devices possess a relatively large bandwidth (up to 580 nm) of the relative spectral response; (b) for oxide thickness Xox Rp (projected range), the low energy implant yields devices with good blue response; (c) for Xox equal or larger than Rp a pronounced shift of the peak responsivity wavelength toward the visible spectrum of the light occurs; (d) a distinctive feature of devices consists in the high peak values of the short-circuit current density under AM1 insolation (in excess of 33 mA/cm2); (e) the preservation of SiO2 layer in the finished devices improves their electro-optical characteristics.
Regrowth of Implanted-Amorphous Si: Furnace to Laser Annealing
Authors: Mayer James W. 
Published: March 2011

ABSTRACTHigh-quality, epitaxial layers regrown from ion-implanted, amorphous Si are an important element in integrated circuit fabrication. Two regimes are well-characterized and understood: furnace annealing in the solid phase from 500° to 1000°C and pulsed-laser annealing in the liquid-phase. Growth rates have been measured in the range from 1 Å/sec in the solid phase to 10 m/sec in the liquid phase. Impurity redistribution is in hand and only the strong enhancement of solid phase rates due to the presence of 0.1 at. % or greater of dopants remains as a controversial issue.The emergence of rapid thermal annealing (10 to 20 sec at 1000 to 1100°C) as an attractive method of restoring crystal order has introduced a new area of controversy; in this case, growth rates and impurity redistribution. The experimental data from several groups will be presented in order to highlight the different mechanisms that have been invoked. The redistribution of implanted B and As will also be discussed.
Interface and Bulk Oxide Damage Induced by Boron Implantation
Authors: Wong H. , Cheung N.W. 
Published: March 2011

ABSTRACTInvestigations were carried out on the damage of SiO2 and the Si-SiO2 interface induced by boron implantation through polysilicon/SiO2 /p-Si structures with doses up to 1014cm−2 and annealed at 950°C. Using the constant voltage stressing technique, both capacitance-voltage and thin-oxide tunneling current measurements showed that both electron trapping and hole trapping are increased, and that ion-induced electron trapping overcompetes hole trapping for boron doses higher than 5×1013cm−2.
Magnetic Properties of Ions Implanted in Glass; Fe in SiO2
Authors: Weeks R.A. , Silva M.C. , Kordas G. , Kinser D.L. , Martinelli J. , Appleton B.R. 
Published: March 2011

ABSTRACTSilica glass platelets have been implanted with Fe(+) ions, 125 KeV and 10⋀-5 A to doses of 10⋀14 cm⋀-2, 10⋀15 cm⋀-2, 10⋀16 cm⋀-2 and 5 x 10⋀16 cm⋀-2. Ion scattering measurements show that the peak of the Fe ion distribution is ~95 nm below the sample surface, approximately Gaussian, with a width at half maximum amplitude of 100 nm. The intensity of a component in the EPR spectra of implanted samples with a width of 300 gauss and an approximately isotropic shape increases with increasing dose. The increase, proportional to dose for doses <⋀16 cm⋀-2, is larger for doses ≥10⋀16 cm⋀-2. In addition for doses ≥10⋀16 cm⋀-2, the component is orientation dependent. Subsequent heat treatments in air at 700° and 800° C alter the shape, intensity, and orientation dependence of the component. The spectral component in as-implanted samples is attributed to paramagnetic states of Fe ions. The threshold for magnetic exchange interactions and consequently long range magnetic ordering at ~300K occurs at a dose ≥10⋀16 cm⋀-2. Data on effects of thermal treatments on intensities and shapes are interpreted in terms of changing chemical composition of precipitating-particles.