bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surfaces of Semi-Fluorinated Block Copolymers Studied Using Nexafs
Authors: Genzer J. , Sivaniah J. E. , Kramer E. J. , Wang J. , Körner H. , Xiang M.-L. , Yang S. , Ober C. K. , Char K. , Chaudhury M. K. , Dekoven B. M. , Bubeck R. A. , Fischer D. A. , Sambasivan S. 
Published: April 2011

ABSTRACTThe molecular orientation within a surface liquid crystalline layer made up of semifluorinated side-groups [-CO-(CH2)x−x-(CF2)yF] (SF groups) attached to the isoprene block of a styrene-isoprene diblock copolymer was determined by analyzing the partial electron yield Cedge NEXAFS signal. The results show that in contrast to the bulk, where the SF groups lie parallel to the diblock copolymer lamellae and thus parallel to the surface, the surface SF groups make an average angle with the surface normal of between 29 and 46° depending on x and y.
UV-Laser Ablation of HFO2 Dielectric Layers on SiO2 for Mask Preparation
Authors: Rubahn K. , Ihlemann J. 
Published: April 2011

AbstractThe thickness dependence of ablation rates following 193nm UV-laser irradiation of single HfO2 layers on fused silica (SiO2) is investigated using scanning electron microscopy and stylus profilometry to determine quantitatively substrate roughness and ablation depth. Thin dielectric films of the investigated kind build up dielectric mirrors, which are patterned to prepare masks for excimer-laser micromachining. The single pulse ablation thresholds are found to increase approximately linearly with increasing HfO2 thickness and consequently the threshold fluence for obtaining clean ablation of the total HfO2 coating increases exponentially with its thickness. At elevated fluences both ablation of the coating as well as ablation of the substrate are observed. The results provide important quantitative values for a future treatment of more complicated multilayer systems of HfO2/SiO2 bilayers.
Synthesis and Characterization of Ferroelectric Thin Films by KrF Excimer Laser Ablation for Memory Applications
Authors: Kumar Ashok , Alam M.R. 
Published: April 2011

AbstractPb(ZrxTi1-x)O3 (lead zirconate titanate or PZT) ferroelectric thin film capacitors are of considerable interest for the realization of memory devices such as nonvolatile random access memories (NVRAMs). The PZT capacitors were prepared on platinized silicon Pt/(100)Si using conducting oxide LaxSr1-xCoO3 (lanthanum strontium cobalt oxide or LSCO) as electrodes. The PZT and LSCO thin films were deposited by the KrF excimer laser ablation technique. The optimum preparation conditions such as oxygen pressure, laser energy influence and substrate temperature were investigated. The PZT and LSCO films grown on Pt/(100)Si are polycrystalline. The crystallographic properties of the films were determined using X-ray diffractometer (XRD) method. The electrical characterizations of the films including hysteresis loop, fatigue, and retention properties were determined by the RT66A Standardized Ferroelectric Test System.
Laser Deposited Iron Garnet Films for Magneto-Optic Applications
Authors: Kim H. , Duan M. , Grishin A.M. , Rao K.V. 
Published: April 2011

AbstractSubmicron thick Bi, Ga substituted dysprosium iron garnet films were laser deposited on Gd3Ga5O12(GGG) and ceramic glass substrates at room temperature and then post annealed by rapid thermal annealing (RTA). From Faraday rotation studies, the films deposited on glass substrates are found to exhibit perpendicular magnetic anisotropy, Faraday rotation of 0.88 deg / μm, and coercive field Hc of 0.88 kOe. On the other hand, films deposited on GGG substrates with the same processing parameters are found to exhibit perpendicular anisotropy, but with much smaller values for Faraday rotation(0.03 deg; μm) and coercive field Hc(0.018 kOe). The uniaxial magnetic anisotropy with easy magnetization axis perpendicular to the film surface is caused by the stress induced on the polycrystalline film / substrate interface. The effect of changing the oxygen pressures, in the range of 20 to 100 mTorr during the deposition process, on the crystalline structure as well as coercive field and Faraday rotation angle are also presented.
The Effect of Gas-Surface Interactions on Laser-Generated BaTiO3Plumes
Authors: Paul Albert J. , Hastie John W. , Bonnell David W. , Schenck Peter K. , Vaudin Mark D. 
Published: April 2011

AbstractTwo models, based on hydrodynamic and Direct Simulation Monte Carlo approaches, have been investigated for the simulation of species fluxes arriving at substrates during pulsed laser deposition of thin films. The models are assessed in light of the results of mass spectrometric and optical imaging observations of the plume. Model predictions of film composition are compared with the results of microscopic compositional analysis across a deposited BaTiO3film. The spatial distributions of the relative abundance of total Ba and Ti were a particular focus of this study, with the latter model giving the best agreement with experiment. The Monte Carlo simulation results indicate that the incoming concentration ratio of total Ba to Ti, across the substrate surface, is strongly modified by gas collisions within a compressed region that forms between the infalling plume and the substrate surface, and also by momentum exchange (scattering) between the lighter plume species and the added background gas.
Defects and Interfaces in III-Nitride/Sapphire Thin Film Heterostructures
Authors: Oktyabrsky S. , Dovidenko K. , Sharma A. K. , Narayan J. 
Published: April 2011

AbstractHigh quality III-nitrides and zinc oxide thin film heterostructures have been fabricated using pulsed laser deposition (PLD) on highly lattice mismatched sapphire substrates. The structural quality of PLD films grown at 700-800°C is comparable with those grown by MOCVD in the temperature range 950-1050°C. The PLD films were found to be single crystalline with columnar structure having the dislocation density of ~1010 cm2 at a film thickness 150-200 nm. The typical structure of defects and interfaces in GaN and AIN films is analyzed and compared with those obtained from specimens grown by MOCVD at much higher temperatures. Low temperature PLD (< 780°C) does not require additional atomic nitrogen source to compensate for the loss of nitrogen due to thermal decomposition of the nitride layer. At slightly higher temperatures the GaN films exhibit rough morphology and formation of the cubic zinc-blende phase which is more stable against nitrogen deficiency than wurtzite phase. A mechanism of formation of zinc-blende phase has been identified. Growth of GaN on lattice-matched ZnO/sapphire buffer layers showed the formation of cubic spinel ZnGa2O4 intermediate layer.
In Situ Initial Growth Studies of SrTiO3 on SrTiO3 by Time Resolved High Pressure RHEED
Authors: Koster Gertjan , Rijnders Guus J.H.M. , Blank Dave H.A. , Rogalla Horst 
Published: April 2011

AbstractThe initial growth of pulsed laser deposited SrTiO3 on SrTiO3 has been studied using high pressure Reflection High Energy Electron Diffraction (RHEED) and Atomic Force Microscopy (AFM). For this, we developed a Pulsed Laser Deposition (PLD)-RHEED system, with the possibility to study the growth and to monitor the growth rates, in situ, at typical PLD pressures (10-50 Pa). Using perfect single crystal SrTiO3 substrate surfaces, we observe true 2D intensity oscillations at different temperatures. Simultaneously, information on the diffusion of the deposited material on the surface could be extracted from the relaxation of the intensity after each laser pulse. The characteristic times depend on pressure and temperature as well as the 2D coverage during growth.
A Theoretical Model for Steam Laser Cleaning
Authors: Lu Y. F. , Zhang Y. , Song W. D. , Low T. S. 
Published: April 2011

AbstractA theoretical model for removal of tiny particles from solid surface covered with a thin liquid film by laser cleaning is established by taking adhesion force and cleaning force into account. When pulsed laser irradiates on the solid surface coated with a thin liquid film, a sheet of liquid near the liquid/substrate interface can be superheated through thermal diffusion. The rapid growth of vapor bubbles inside the superheated liquid can generate transient stress wave with high pressure, large enough to expel micron and sub-micron particles from the contaminated surface. By calculating the adhesion force and cleaning force, the cleaning threshold of laser fluence can be predicted from this theoretical model. The difference between cleaning force and adhesion force increases quickly along with the laser fluence and leads to higher cleaning efficiency.
Refractive Index Modification During Deposition of Silicon Oxynitride Films Prepared by Reactive Laser Ablation
Authors: Machorro R. , Soto G. , Samano E. C. , Cota-Araiza L. 
Published: April 2011

AbstractInhomogeneous low-k thin films of SiOxNy have been deposited by laser ablation of a Si3N4 sintered target in presence of oxygen gas. The high oxidation rate of silicon nitride has been used to control the stoichiometry of the films by modifying the oxygen partial pressure. The refractive index of the deposited material was able to be tailored at any value between 1.47 (SiO2) to 2.03 (Si3N4) by this approach. In situ optical characterization of the growing films was possible using kinetic and spectro ellipsometry. The refractive index was determined by applying the Effective Medium Approximation (EMA) and considering a mixture of SiO2, Si3N4, and voids. The volumetric composition obtained by ellipsometry was compared to the results determined by AES and XPS characterization. The purpose of this application is to show that reactive PLD can be used to produce high quality optical filters.
Determination of The Diffusion Mechanism by A Method with New Possibilities: Nuclear Scattering of Synchrotron Radiation
Authors: Sepiol B. 
Published: April 2011

ABSTRACTThe elementary diffusion jump in crystalline solids can be determined by methods derived from nuclear physics. With these methods not only diffusion rate(s) but also diffusion vector(s), i.e. the complete diffusion mechanism can be deduced. We report on a new method for probing the elementary diffusion jumps in crystalline lattices on an atomistic scale and demonstrate its potential by a study of 57Fe diffusion in different intermetallic alloys. Compared to the results of conventional tracer (macroscopic) technique, the new method provides clear and doubtless statements concerning the direction and distance of elementary jumps. One can also determine (though less precisely than with tracer diffusion), iron diffusion coefficients.
Grain Boundary Diffusion and Solute Segregation in Polycrystals and Oriented Bicrystals
Authors: Herzig Chr. , Surholt T. 
Published: April 2011

ABSTRACTMeasurements of solute GB diffusion in Cu and Ag polycrystals were carried out in Harrisons type-B and type-C kinetic regime using 75Se, 195Au, 63Ni radioisotopes. In the B-regime at high temperatures, the GB diffusion parameter sδDGB was determined (s being the GB segregation factor, δ the GB width and DGB the GB diffusion coefficient), while in the C-regime at low temperatures DGB values were measured directly. The investigations of these differently behaving solute–solvent systems on Cu and Ag basis yield information on solute GB diffusion and segregation in relation to solute–solvent atomic binding and solute–vacancy interaction in the bulk and in GBs. The GB diffusion of 64Cu and 195Au in a series of near ∑ = 5, Θ = 36.9° (310) [001] Cu tilt GBs and of 71Ge in a series of near ∑ = 7, Θ = 38.2° (123) [111] Al tilt GBs in dependence on the tilt angle Θ and on the temperature was studied. A characteristic minimum in the GB diffusion parameter and a maximum in the activation energy was observed at the ideal CSL GBs.
Modeling the Effect of Irradiation and Post-Irradiation Annealing on Grain Boundary Composition in Austenitic Fe-Cr-Ni Alloys
Authors: Allen T.R. , Busby J.T. , Kenik E. A. , Was G.S. 
Published: April 2011

ABSTRACTMany irradiation effects in Fe-Cr-Ni alloys such as radiation-induced segregation, radiation-enhanced diffusion, and void swelling are known to vary with bulk alloy composition. The development of microstructural and microchemical changes during irradiation and during post-irradiation annealing is determined by the rate of diffusion of point defects and alloying elements. To accurately predict the changes in grain boundary chemistry due to radiation-induced segregation and post-irradiation annealing, the composition dependence of diffusion parameters, such as the migration energy, must be known. A model has been developed which calculates migration energies using pair interaction energies, thereby accounting for the effect of composition on diffusivity. The advantages of this calculational method are that a single set of input parameters can be used for a wide range of bulk alloy compositions, and the effects of local order can easily be incorporated into the calculations. A description of the model is presented, and model calculations are compared to segregation measurements from seven different iron-chromium-nickel alloys, irradiated with protons to doses from 0.1 to 3.0 dpa at temperatures between 200°C and 600°C. Results show that segregation trends can be modeled using a single set of input parameters with the difference between model calculation and measurement being less than 5 at%, but usually less than 2 at%. Additionally, model predictions are compared to grain boundary composition measurements of neutron irradiated 304 stainless steel following annealing. For the limited annealing data available, model calculations correctly predict the magnitude and time scale for recovery of the grain boundary composition.
New Tight-Binding Method for Simulation of Defect Configurations, Creation and Diffusion Mechanisms in Solids: Application to Silicon
Authors: Khakimov Zokirkhon M. 
Published: April 2011

ABSTRACTThis paper presents the self-consistent tight-binding method of new generation which, unlike other tight-binding methods, allows one to calculate structural energies of multiatomic systems (molecules, clusters, defects in solids) and their spectroscopic energies in the framework of the same computational scheme and with comparable accuracy. Reliability of the method is illustrated considering defect state problems in crystalline and amorphous silicon (electron-enhanced-atomic diffusion, metastable defect creation, defects with effective-negative correlation energies, etc.) and comparing obtained results with ab initio calculations and experimental data.
Properties of Vacancies in Silicon Determined by Out-Diffusion of Zinc from Silicon
Authors: Giese A. , Bracht H. , Walton J.T. , Stolwijk N.A. 
Published: April 2011

ABSTRACTWe present out-diffusion of Zn in Si as a new method to study properties of Si vacancies. Out-diffusion experiments were performed on homogeneously Zn-doped Si samples at 1107°C and 1154°C. The resulting concentration-depth profiles were measured by means of spreading-resistance profiling. Based on a diffusion model in which Zn migrates simultaneously via the kick-out and the dissociative mechanism all experimental profiles were modeled by computer simulations. The calculations reveal that out-diffusion of Zn from Si occurs to a considerable extent via the dissociative mechanism. Hence, vacancy properties like the equilibrium concentration and the transport capacity can be extracted from profile fittings. The results are compared with literature data deduced from in-diffusion experiments.
Ge Diffusion in SnTe Crystal
Authors: Kaportseva O.E. , Yashina L.V. , Bobruiko V.B. , Safonov D.V. , Kozlovsky V.F. , Shtanov V.I. , Shatalova T.B. 
Published: April 2011

ABSTRACTThis work is devoted to the study of Ge diffusion in crystalline Sn1-δTe1+8 with δ=0.0065±0.0008 in temperature range T=878-973 K by electron probe microanalysis and layer by layer X-ray analysis. For the latter lattice constant dependence on composition was determined: a(Å)=a(SnTe)-(0.368±0.008)× where 0<×<0. 1. Activation energy was found to be about 1.3 eV, much less than in the case of Ge diffusion in PbTe.
Activation Enthalpy of Sb Diffusion in Biaxially Compressed SiGe Layers
Authors: Kuznetsov A.Yu. , Cardenas J. , Svensson B.G. , Larsen A. Nylandsted , Hansen J. Lundsgaard 
Published: April 2011

ABSTRACTEnhanced Sb diffusion in biaxially compressed Si1-xGex layers is observed. Assuming the prefactors to be stress independent the Sb diffusion coefficients in biaxially compressed Si0.9Ge0.1 and Si0.8Ge0.2 were extracted as 0.4 × 102 exp[−(3.98(eV)±0.12)/kT] and 1.3 × 102 exp[−(3.85(eV)±0.12)/kT] cm2/s, respectively. The activation volume of Sb diffusion in Si1-xGex (× ≤ 0.2) is estimated to be close to Ω, where Ω is the volume corresponding to a silicon lattice site.
Interplay between Anion Rotation and Cation Transport in the Plastic High-Temperature Phase of Sodium Ortho-Phosphate
Authors: Funke K. , Wilmer D. , Banhatti R. D. , Witschas M. , Lechner R. E. , Fitter J. , Jansen M. , Korus G. 
Published: April 2011

ABSTRACTThe high-temperature phase of sodium ortho-phosphate, α-Na3PO4, belongs to the class of ion conducting plastic crystals, i.e., it is characterized by a dynamic rotational disorder of its poly-atomic anions and, at the same time, by a considerable translational mobility of its cations. During the past decade, the possibility, nature, and importance of a dynamic interplay between the two kinds of motion have been a subject of continued controversy. Proponents of a strong interplay coined the expression “paddle-wheel mechanism”. In our present contribution we report, for the first time, on the results ofdynamicexperiments probing the elementary steps of anionic and cationic motion individually. The techniques utilized in this study are coherent quasielastic neutron scattering and high-frequency conductivity spectroscopy, respectively. The data are complemented by anab-initiomolecular-dynamics simulation. Our results provide a view of the movement of anions and cations and of correlations between them. Strong dynamic coupling is detected between the octahedrally coordinated sodium ions and nearby oxygen ions. For translational sodium-ion transport, a chain mechanism appears to be operative.
A Study of Diffusion of Li+ in the [NZP] Network
Authors: Bhuvaneswari G. , Varadaraju U.V. 
Published: April 2011

ABSTRACTLi+ has been incorporated in the 3D -framework of PbM3+M4+P3O12 by soft chemistry method using n-butyl lithium at RT. It is shown that the framework of the [NZP] structure remains intact upon Li+ insertion and provides a three dimensional interstitial pathway for Li+ ion diffusion.
Positron Studies of Defects in Nitrogen and Carbon Implanted Titanium
Authors: Soltani-Farshi M. , Baumann H. , Anwand W. , Brauer G. , Coleman P.G. , Richter E. , Kreissig U. , BETHGE K. 
Published: April 2011

ABSTRACTModification of materials by ion beams creates defects and defect formation processes. The implantation of nitrogen into titanium influences the hydrogen content in this metal. Hydrogen accumulation enhances hydrogenations in the implanted region. This effect may have important consequences, because excessive hydrogen accumulation generally leads to precipitating hydrids in the matrix lattice and the metal undergoes degradation of its mechanical properties. Many studies have shown that defects in metals trap light gas atoms like H or He which are solved or implanted in the sample. Therefore, the decoration of defects with these atoms is a method to trace defect concentrations and to study the trapping and detrapping mechanism. Mobile defects can be trapped at implanted atoms, at inhomogeneities or at inner surfaces like grain boundaries or interfaces of different phases. Using the slow positron beam technique the traps for hydrogen attributed to vacancy-type defects have been investigated in cp-Ti implanted with nitrogen or carbon.The concentration of hydrogen has been detected by the 15N profiling technique (1H(15N,αγ)12C). The nitrogen and carbon content were measured by 15N(1H,αγ)12C and 13C(p,γ)14N reaction, respectively.
Investigating Islet Immunoisolation Parameters Using Microfabricated Membranes
Authors: Desai T.A. , Hansford D.J. , Chu W.H. , Huen T. , Ferrari M. 
Published: April 2011

AbstractThe immunoisolation of xenogeneic hormone-secreting cells is a promising therapy for a wide variety of diseases including diabetes, Parkinson's, and hemophilia. By utilizing microfabrication technology, silicon biocapsules can be fabricated with membranes having precisely controlled and uniform pore sizes, allowing one to optimize parameters specifically for the encapsulation of specific hormone-secreting cell types. This study investigates immunoisolation parameters using microfabricated silicon-based membranes, with uniform membrane pore sizes in the tens of nanometer range. The permeability of IgG was studied in microfabricated biocapsules with various pore sized membranes. In addition, immunoisolative characteristics were monitored by assessing viability and functionality of islets within biocapsules.
High Temperature Oxide for NVM Interpoly Dielectric Applications
Authors: Yater J. A. , Esho B. , Paulson W. M. 
Published: April 2011

ABSTRACTHigh quality interpoly dielectrics are required for non-volatile memories (NVM) in order to achieve long term data retention and endurance over many program/erase cycles. LPCVD high temperature oxide (HTO) deposited at 800°C-900°C is investigated for use in oxide-nitride-oxide (ONO) interpoly dielectric stacks. HTO allows for reduced thermal budgets, improved conformal coverage at edge features and more flexibility in scaling the ONO stack compared to thermal oxide layers. SIMS and atomic force microscopy results indicate that smooth, high quality films are deposited with a rms roughness of 0.12nm. Etch rates of as-deposited films are lowered 35% following several densification anneals. Field strengths (at 1μA) of 7-8MV/cm and leakage currents in the pA range are measured. Centroid measurements on sressed oxides show traps to be located at the HTO/polysilicon interfaces. Finally, double poly flash memory cells fabricated with ONO stacks containing HTO top oxide show improved field strength and data retention.
The Importance Of Pairing Reactions For The Modeling Of Defect-Dopant Interactions In Silicon
Authors: Bork I. , Schwerin A. v. , AG Siemens 
Published: April 2011

ABSTRACTIn this article it is shown that the reactions between dopants and point defects in silicon are slow enough to play a significant role for low temperature transient enhanced diffusion (TED). As a consequence, diffusion models based on the assumption of local equilibrium between dopants and dopant-defect pairs highly overestimate TED at temperatures below 800°C. Without this assumption, i.e. when full dynamic pairing of dopants is included in simulations, good agreement to experimental results is achieved.
Ultra Shallow Junction Formation by RTA at High Temperature for Short Heating Cycle Time
Authors: Saito S. , Shishiguchi S. , Mineji A. , Matsuda T. 
Published: April 2011

ABSTRACTIn accordance with decrease of device size, ultra shallow junctions are required for realizing superior device performance. Enhanced diffusion caused by implantation is a crucial factor to realize ultra shallow junctions. Not only implant but also RTA conditions are key factors to suppress enhanced diffusion. In this paper, process conditions to minimize enhanced diffusion are discussed. Implant ion species, energy, dose and beam current parameters are investigated for implantation and temperature, time and ramping rate parameters are investigated for RTA. Important result is that optimization of not only implant but also RTA conditions should be carried out in order to fabricate ultra shallow junctions.