bluuebunny/crossref_metadata_2025_split huggingface dataset:
Picosecond Time-Resolved Optical Studies of Plasma Formation and Lattice Heating in Silicon
Authors: Lompré L. A. , Liu J. M. , Kurz H. , Bloembergen N. 
Published: March 2011

ABSTRACTTime-resolved studies of reflectivity and transmission at 0.532 μm, 1.064 vm and 2.8 μm of thin silicon films following irradiation with ps pulses at 0.532 μm have been performed. The formation of the electron-hole plasma and the evolution of lattice temperature is investigated as a function of pump fluence and time delay. Quantitative determination of the plasma densities and lattice temperature up to the melting temperature shows that the maximum plasma density is limited to ∼ 1 × 1021 cm−3 by Auger recombination even on a time scale of picoseconds at fluences sufficient to cause the phase transition. The thermal nature of the phase transition is confirmed.
Beam-Recrystallized Device-Worthy Films of Si on SiO2 via Control of the Grain Boundary Location
Authors: Colinge J.P. , Bensahel D. , Alamome M. , Haond M. , Leguet C. 
Published: March 2011

ABSTRACTDevice-worthy films of silicon on SiO2 have been produced using laser annealing and antireflection stripes. If no seeding is used, grain boundaries will be localized beneath the stripes; with seeding, large-area single crystals can be grown, of uniform <100> orientation. N-channel transistors show a mobility of 620 cm2/V.s and present leakage currents which can be reduced, however, down to a few pA/um when the substrate (back gate) is negatively biased to − 5 V. Ring oscillators have also been made, which oscillate with a delay per stage of 1 nsec.
Laser Annealing of GaP and GaAs in High-Pressure Argon Gas Ambients
Authors: Sato Fumio , Sunada Tadasu , Chikawa Jun-ichi 
Published: March 2011

ABSTRACTPulsed laser annealing has been made for Te or Znimplanted GaP and Si-implanted GaAs in argon gas atmospheres in a pressure range of 1 to 1000 bar. Optical absorption measurement indicates that pulse annealing under pressures higher than 300 bar forms surface layers with a high crystallinity without appreciable evaporation of P or As. This pressure effect is discussed from the viewpoint of diffusion length of evaporated atoms during the annealing time.
Rapid Thermal Annealing of Si-Implanted GaAs
Authors: Rosenblatt D.H. , Hitchens W.R. , Shatas S. , Gat A. , Betts D.A. 
Published: March 2011

ABSTRACTHeatpulse rapid thermal annealing was used to activate Si implants of 3.5 × 1012cm−2 at 100 keV and 1.0 × 1013 and 1.0 × 1014cm−2 at 200 keV into semi-insulating GaAs. The effects of Si3N4 encapsulation, anneal temperature and time, and substrate Cr-doping level were investigated. The annealed samples were characterized with C-V, Van der Pauw, differential Hall, and SIMS measurements. Conventional furnace anneals were carried out for comparison, and in all cases, Heatpulse anneals produced sharper carrier concentration profiles. 84% electrical activation was obtained for the 200 keV, 1.0 × 1013 cm−2 implant after a 950°C, 5 sec. Heatpulse anneal. Capped Heatpulse anneals produced less Cr depletion from the implanted region than furnace anneals.
Theoretical Analysis of Homogeneity and Surface Degradation During Pulsed Electron Beam Annealing of GaAs and InP
Authors: Laugier A. , Barbier D. , Chemisky G. 
Published: March 2011

ABSTRACTPEBA induced thermal effects in GaAs and InP have been simulated. Monte-Carlo calculation has been used to determine universal electron energy loss functions in the 5–50 keV energy range for these materials. Similar electron depth-dose profiles of a polykinetic electron beam pulse is deduced in both GaAs and lnP. A simple adiabatic approach is sufficient to establish relationship between melting depths and fluences. Thermal effects homogeneity and surface degradation are discussed for both crystalline and amorphous materials using variable electron energy deposition profiles. Correlation is made between experimentally measured degradation thresholds and calculated fluence windows within which melting effects are expected.
Rapid Thermal Annealing of Composite TaSi2/n+ Poly-Si Silicide Films
Authors: Kwong D.L. , Kwor R. , Tsaur B.Y. , Daneshvar K. 
Published: March 2011

ABSTRACTThe formation of composite TaSi2/n+ Poly-Si silicide films through the use of rapid thermal annealing (RTA) is investigated by x-ray diffraction, four point probe, scanning Auger microprobes (SAM) with ion sputter etching, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and capacitance-voltage (C-V) measurements. 0.2 μm polysilicon is deposited on oxidized Si wafer by LPCVD and doped with phosphorus. A layer of 2200 A TaSix is then co-sputtered on polysilicon samples from separate targets. These as-deposited films are then annealed by RTA in an argon ambient for 1 sec. and 10 sec. at various temperatures. X-ray diffraction and SAM results show the rapid formation of a uniform stoichiometric tantalum disilicide via Si migration from polysilicon. TEM micrographs show simlilar results for samples annealed at 1000°C in furnace for 30 min. or by RTA for 1 sec., exhibiting average grain size greater than 1000 A. Sheet resistance of samples annealed by furnace annealing and RTA are comparable. SEM micrographs indicate that the surface morphology of the RTA-annealed sample is superior to that obtained by furnace annealing. These results show that RTA may offer a practical solution to low-resistivity silicide formation in VLSI circuits.
Annealing of High Dose C Implanted Si by Pulsed Electron Beam
Authors: Durupt P. , Barbier D. , Laugier A. 
Published: March 2011

ABSTRACTHigh dose (1–7 1017cm−2), low energy (10–40 keV) C implanted Si samples were annealed by conventional thermal procedure and by pulsed electron beam. Characterization is performed by I.R., electron diffraction and Rutherford Backscattering. Effect of PEBA is equivalent to thermal annealing at 900°C. No C redistribution occurs and a poor recrystallization of the SiC formed during implantation is observed.
Pulsed Laser Melting of Amorphous Silicon: Time-Resolved and Post-Irradiation Studies
Authors: Lowndes D. H. , Wood R. F. , White C. W. , Narayan J. 
Published: March 2011

ABSTRACTMeasurements of the time of the onset of melting of self-implantation amorphized (a) Si, during an incident laser pulse, have been combined with modified melting model calculations and measurements of surface melt duration to demonstrate that the thermal conductivity, Ka, of a-Si is very low (≃0.02 W/cm-K). Ka is also shown to be the dominant parameter determining the dynamical response of ionimplanted Si to pulsed laser radiation; the latent heat and melting temperature of a-Si are relatively unimportant. Cross-sectional transmission electron micrographs on implantation-amorphized Si layers of several different thicknesses show that for energy densities less than the threshold value for complete annealing there are usually two distinct regions in the re-solidified a-Si, consisting of fine-grained and large-grained polycrystalline Si, respectively. The presence of the fine-grained poly-Si suggests that bulk nucleation occurs directly from the highly undercooled liquid phase. Thermal melting model calculations suggest that the nucleation temperature, Tn is ≃1200°C.
Secondary Grain Growth in Heavily Doped Polysilicon During Rapid Thermal Annealing
Authors: Batra S. , Park K. , Lobo M. , Banerjee S. 
Published: March 2011

AbstractTo successfully implement Silicon-on-Insulator (SOI) technology using polysilicon-on-oxide, it is necessary to maximize the grain size such that the active devices are entirely within very large single crystal grains. A drastic increase in grain size in polysilicon has been reported due to secondary grain growth in ultra-thin, heavily n-type doped films upon regular furnace annealing. Very little work has been undertaken, however, to study secondary grain growth during Rapid Thermal Annealing (RTA).This paper is a study of the grain growth mechanism in heavily P-doped, amorphous silicon films during RTA. Secondary grains as large as 16 μm have been obtained in 160 nm thick films after a 180 s RTA at 1200 °C, representing a grainsize- to-film-thickness-ratio of 100:1. This is the largest secondary grain size and grain-size-to-film-thickness reported in the literature. A detailed analysis of negatively charged silicon vacancies has also been employed to explain the lower activation energy (1.55 eV) of secondary grain growth compared to that of normal grain growth (2.4 eV).
Raman Studies of Stress-Induced Phase Transformations in Titania Films
Authors: Exarhos Gregory J. , Hess Nancy J. 
Published: March 2011

AbstractTime-resolved micro-Raman spectroscopy is used to follow the amorphous to crystalline phase transformation in sol-gel deposited titania films induced thermally or through the action of applied hydrostatic pressure in a diamond anvil cell. Time-dependent phonon intensities intrinsic to the growing phase are related to the volume fraction of crystallite present at any time. The sigmoidally generated curves can be modeled in terms of modified Avrami ingrowth kinetics in which diffusion of the amorphous phase to the nucleation center is restricted by the morphology of the evolving phase. Phonon frequency and linewidth measurements during the course of the transformation probe changes in film stress and particle size which are used to understand the mechanistics of the transformation. Raman measurements also are used to derive a phase stability diagram for titania films.
Oscillatory Interlayer Exchange Coupling Through Cu and Various Transition Metals
Authors: Parkin S.S.P. 
Published: March 2011

AbstractWe show that oscillatory interlayer exchange coupling of thin magnetic layers through metals is a general phenomenon present in almost all the transition and noble metals. Surprisingly the period of the oscillations is approximately the same, about 10Å, in all these metals with the sole exception of Cr for which the period is significantly longer. The strength of the coupling varies systematically throughout the 3d, 4d and 5d transition metals increasing exponentially along each of the transition metal periods and increasing from the 5d to 4d to 3d periods. These results appear to be inconsistent with simple Ruderman-Kittel-Kasuya-Yosida (RKKY) based models.
Theory of Oscillatory Exchange Between Magnetic Layers Through a Nonmagnetic Transition–Metal Spacer
Authors: Mathon J. 
Published: March 2011

AbstractA general theory of oscillations in the exchange coupling between two transition metal ferromagnets separated by a nonmagnetic transition metal spacer is developed. A close analogy between oscillations in the exchange coupling and de Haas-van Alphen oscillations is established and exploited to show that the period, asymptotic decay, and temperature dependence of the oscillations are determined by properties of the d band Fermi surface in the spacer layer. The theory accounts qualitatively and even semiquantitatively for all the salient experimental features of the oscillations in the exchange coupling observed recently in Co/Ru, Co/Cr, and Fe/Cr superlattices.
Epitaxial Co-Cu Superlattices
Authors: Schuler Elizabeth , Elagoz Sezai , Vavra William , Lamelas Frank , He Hui David , Clarke Roy 
Published: March 2011

AbstractWe describe measurements on the magnetic properties of Co-Cu superlattices in which the Co layer thickness was fixed at 20 Å and the Cu thickness was varied from 4 Å to 24 Å. The samples were grown on Ge-buffered (110) GaAs by molecular beam epitaxy. X-ray scattering and in-situ RHEED indicate that the multilayers are oriented in the (111) direction with the Co layers stacked in an fcc arrangement. Our interest in this series of samples lies in their unusual hysteresis curves which show distinct transitions. We have found that the appearance of these transitions is directly related to the Cu thickness, indicating the presence of complex spin configurations as a consequence of competing interactions. The results are not consistent with a simple RKKY antiferromagnetic coupling.
Stepped Fe(100) and V/Fe(100) Magnetism
Authors: Vega A. , Rubio A. , Balbas L.C. , Dorantes-Davila J. , Demangeat C. , Mokrani A. , Dreysse H. 
Published: March 2011

AbstractWe have investigated the magnetic arrangment of 3d transition-metal stepped surface by using a self-consistent real-space tight-binding method. As expected, the presence of steps modifies locally the properties of a transition-metal surface. We emphasized the influence of atomic environment. We found for the (100)-Fe surface, an enhancement of the magnetic moments of the external edge of this step as compared to the flat surface. The results are not very sensitives to the step length. More striking is the case of the (100)-V stepped surface where atoms at the external edge display a large magnetic moment.
Investigation of Magnetic Order in Iron Oxide-Nickel Oxide Superlattices with Modulation Wavelength Less Than 80 Å
Authors: Berry S. D. , Lind D. M. , Chern G. , Mathias H. , Testardi L. R. 
Published: March 2011

AbstractWe have investigated the magnetic order, using SQUID magnetometry, for short modulation wavelength Fe3O4/NiO superlattices, grown on single crystal MgO. Ferrimagnetic Fe3O4 has a saturation moment of ~500 emu/cm3 at 0 K and a Curie temperature of 858 K, while bulk NiO is antiferromagnetic with a NMel temperature of 525 K. Very high crystalline quality with little interdiffusion is indicated by X-ray diffraction, SEM, optical microscopy, and in-situ RHEED, and the samples show highly anisotropic electrical conductivity which also indicates the strong modulation present. Long wavelength samples (Amod > 200 Å) have a behavior only slightly different from that expected from bulk Fe3O4, but for Amod<80 Å, spontaneous magnetization is replaced by paramagnetism, with weak temperature dependence (not I/T) from 5 K to 400 K.
Theoretical Studies of Spin Dependent Scatterings of Electrons from Ferromagnetic Surfaces and Ultra Thin Films
Authors: Ormeci A. , Gokhale M. P. , Hall Burl M. , Mills D. L. 
Published: March 2011

AbstractWe summarize results of our recent theoretical studies of spin dependent scattering of electrons from ferromagnetic surfaces. We obtain an excellent account of both the energy and angle variation of the exchange asymmetry reported by Waller and Gradmann in their SPLEED study of the Fe(110) surface, and of spin dependent asymmetries in the transmission of photoelectrons through an ultra thin film of Fe on Cu(100). Potentials supplied by Fu and Freeman enable us to account for the data, with use of ground state potentials generated by ab initio methods.
Investigation of Surface Magnetism by Detection of Polarized Light Emitted After Low Energy He+ Scattering off a Fe(110) Surface
Authors: Schleberger M. , NÄrmann A. , Heiland W. , Huber C. , Kirschner J. 
Published: March 2011

AbstractWe present data from low-energy He+ ion scattering off a magnetized Fe(110) surface where we monitored the circular polarization of the light emitted from particles neutralized into excited states. We investigated the dependence on incident energy, incident angle and magnetization for a singlet and a triplet transition. As expected, there is no dependence on magnetization for the singlet state, but for the triplet transition we observed a difference in the circular polarization of as high as 32% when changing the direction of the magnetization.
Relations of Corrosion Resistance, Coercivity, and Magnetizability of Modified Nd-Fe-B Sintered Magnets to Their Microstructure
Authors: Hirosawa Satoshi , Tokuhara Koki , Mino Shuji , Matsui Toshiyuki , Morii Kenji , Nakayama Yutaka 
Published: March 2011

ABSTRACTBrief reviews on corrosion and coercivity mechanisms of sintered Nd-Fe-B magnets are given. Results of recently undertaken transmission electron microscopic study of Nd15 - Fe78-xCoxB7 sintered magnets (x = 3, 6 and 10) are presented. Micro-beam electron diffraction patterns obtained from Nd-Co phases in these magnets could be indexed according only to an orthorhombic cell of Nd3 Co among the binary Nd-Co compounds for x = 3 to 10. Relations of coercivity and magnetizability of this type of magnets to their microstructure are discussed in connection to the effects of V or Mo addition which are to enhance coercivity and to improve magnetizability. It is suggested that a decrease in the local demagnetization effects resulting from a decrease in the width of the grain size distribution due to these-additives is the origin of the enhancement of coercivity and the improvement of magnetizability.
Magnetic Order and Structure of Ultrathin Films and Multilayers
Authors: Lugert G. , Bayreuther G. , Lehner S. , Gruber G. , Bruno P. 
Published: March 2011

ABSTRACTUltrathin epitaxial films grown in UHV – Fe(110) on Au(111) and Ag(111), Co(0001) on Au(111) – , sputtered Fe films between Ag and sputtered Fe/Au multilayers were studied by SQUID magnetometry and Mössbauer spectroscopy (CEMS). It could be shown that the magnetic anisotropy relative to the film normal, the, ground state magnetic moment per Fe atom and thermal spin excitations are affected by the structure of the films. In particular, a more 3-dimensional growth mode in the early state of film formation which is observed except in a certain temperature range around 300 K reduces the apparent magnetic interface anisotropy and the ferromagnetic ground state moment, and it enhances the thermal spin fluctuations and the tendency for superparamagnetic relaxation in the thinnest films.
Nanoscale Engineered Ceramics From Zeolites: Creating The Ideal Precursor For High-Quality Cordierite
Authors: Bedard Robert L. , Flanigen Edith M. 
Published: March 2011

ABSTRACTThis paper reports the engineering of an ideal zeolite-derived cordierite precursor and addresses the various technological issues that are encountered in the zeolite-to-ceramic process. Mg-exchanged zeolite B (SiO2/Al2O3=2.5) collapses to an amorphous powder at temperatures between 600 and 800°C. The resulting powder can be processed by various standard ceramic methods to give high-quality cordierite parts. The sintering behavior of MgB is described and compared with MgX, another zeolite that is conveniently synthesized with a 2.5 SiO2/Al2O3 ratio. Properties of MgB-derived cordierite are also described.
Low Temperature Studies Of Rare Gases Adsorbed On Molecular Sieve Materials
Authors: Mccann Graham F. , Gameson I. , Steado W.J. , Rayment T. , Barrie P.J. , Klinowski J. 
Published: March 2011

ABSTRACTX-ray diffraction (XRD) and adsorption isotherms have long been traditional methods of characterising molecular sieves. By combining these techniques at low temperatures with variable temperature 129-Xe N.M.R. we now have a fuller understanding of the behaviour of sorbed layers inside these materials. In particular we have observed phase transformations of Xe in a polyhydroxyaluminium-pillared montmorillonite molecular sieve and have developed a model consistent with the data. In addition, using XRD, an interpillar distance of ca. 30Å was calculated. We present the first detailed low temperature studies of 129-Xe N.M.R. on these systems.
Structural Characterization Of Zeolites Using Raman Scattering
Authors: Deckman H. W. , Creighton J. A. , Buckley R. G. , Newsam J. M. 
Published: March 2011

ABSTRACTWe show that the frequencies of certain optically active lattice vibrational modes in a large number of zeolites can be used as direct structural probes. Mode frequencies are found to depend on the cosine of the T-O-T angle and the Si/Al ratio of the framework. The relationship between mode frequency and local framework structure is discussed in terms of a complete lattice dynamics calculation for specific zeolite structures as well as a lattice dynamical model of amorphous glasses.
Cobalt As A Probe Ion In The Synthesis Of CoAPO-5
Authors: Uytterhoeven M. G. , Keyenberg W. A. Van , Schoonheydt R. A. , Leuven K. U. 
Published: March 2011

ABSTRACTDiffuse reflectance spectroscopy (DRS) is an excellent technique for the investigation of the synthesis process of CoAPO-5. The DRS intensities increase concomitantly with the crystallinity during synthesis. DRS is also useful in the characterization of the nucleation stage. The transition from an aluminophosphate-hydrate to a non-hydrated structure is observed.
Synthesis And Characterization Of Pillared Acid-Activated Montmorillonites
Authors: Mokaya Robert , Jones William , Whittle Mavis E. , Davies Mary E. 
Published: March 2011

ABSTRACTPolymeric hydroxy-Al cations were introduced into the interlayer of acid-activated montmorillonites by cation exchange. The resulting pillared materials possessed layer spacings of 18 – 20 Å, surface areas between 250 – 320 m2/g, pore volumes in the range 0.3 – 0.38 cc/g and pore diameters in the range 32 – 40 Å depending on preparation procedures (i.e pillaring temperature and drying method). Powder XRD analysis indicated that the pillars formed were stable to temperatures above 500 °C. The surface acidity of these type of pillared clays was higher than that of pillared non-activated clays. Preliminary studies on their adsorption capacity for chlorophyll showed that they were superior to pillared non-activated clays.
Zirconium Organic Diphosphate-Diphosphonates With Tilted Rigid Pillars.
Authors: Alberti G. , Costantino U. , Vivani R. , Zappelli P. 
Published: March 2011

ABSTRACTThe H2O3PCH(C6H4)2CH2PO3H2 and H2O3PO(C6H4)2OPO3H2 acids were synthesizedT and used to obtain new pillared zirconium phosphonates and organic phosphates in which the pillars are tilted with respect to the layers. The Zr(O3PCH2(C6H4)2CH2PO3) and Zr(O3PO(C6H4)2OPO3) obtained have a good thermal resistance and the distance between the inorganic α-layers joined by the organic pillars is 14.7 and 13.8 Å, respectively. Structural models suggest that the biphenyl groups in the solids are tilted at 140° and 137° with respect to the perpendicular at the layer plane. Solid solutions of the two derivatives over the whole range of composition have also been obtained; the distance between the α-layers changes from 14.7 to 13.8 Å in a continuous way as the diphosphate groups replace the diphosphonate ones, allowing us to suppose a variation of the tilting angles. Attempts to remove the phosphoester in the mixed derivatives by hydrolytic attack, and to replace some pillars with phosphite groups are described.
Formation of A Buried Stacked Insulator by Ion Beam Synthesis
Authors: Skorupa W. , Grotzschel R. , Wollschlagbr K. , Albrbcht J. , Vohse H. 
Published: March 2011

ABSTRACTWe report on the formation and properties of a new type of a buried insulator using combined nitrogen/oxygen implantation with two different implantation energies. In this manner, a stacked layer consisting of silicon dioxide above silicon oxynitride above silicon nitride is formed. Experimental results concerning the impurity profiles, the microstructure and compound formation are presented.
“Equilibrium Oxide” Features of the SIMOX Process
Authors: Hosack H. H. , Hollingsworth J. , El-Ghor M. K. , Joyner K. A. 
Published: March 2011

ABSTRACTThe equilibrium configuration produced when the SIMOX process is carried to the extreme of complete conversion of the silicon film to oxide is described. The thickness of the “equilibrium oxide” produced is modelled using a joined Gaussian approximation to the oxygen implant profile. The “equilibrium oxide” for a 190KeV implant is investigated. This material is found to have a thickness of approximately 5400 angstroms, and to be a very homogeneous film with essentially stoichiometric SiO2 composition. The implications of this work for use of oxides in patterned SIMOX are discussed.
Numerical Simulation of Zone-Melting Recrystallization of Thin Silicon Films With A Tungsten Halogen Lamp
Authors: Robinson Richard D. , Miaoulis Ioannis N. 
Published: March 2011

ABSTRACTA two dimensional numerical simulation of incandescent lamp Zone-Melting Recrystallization (ZMR) was performed. A parametric study examined the thermal effects of lamp intensity, susceptor temperature, and ambient reflectivity, on the melt zone. The melt zone was found to vary linearly with lamp intensity and parabolically with susceptor temperature and ambient reflectivity.