bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diluted Magnetic Semiconductor Magneto-Optic Waveguides for Monolithic-Integration with Semiconductor Optic Devices
Authors: Ando K. , Zaets W. , Watanabe K. 
Published: April 2011

AbstractWe propose to use a paramagnetic diluted magnetic semiconductor Cd1-xMnxTe for magneto-optic waveguides, which can be integrated with semiconductor optic devices. Single crystal Cd1-xMnxTe films are epitaxially grown on GaAs substrates by molecular beam epitaxy method. A good optical confinement is obtained in the waveguide by using a Cd1-yMnyTe clad layer with Mn concentration higher than that of the waveguide core layer.
Magnetic Second Harmonic Generation Studies of Co-Cu Granular Films
Authors: Misuryaev T.V. , Murzina T.V. , Ganshina E.A. , Gushin V.S. , Kazantsev D.V. , Aktsipetrov O.A. 
Published: April 2011

AbstractMagneto-induced optical second harmonic generation (MSHG) is used to study the structural and magnetic properties of Co-Cu granular films. Azimuthal anisotropy of the SHG response reveals an existence of the regular structure of Co nanocrystals. The nonlinear magneto-optical Kerr effect (NOMOKE) is observed for the longitudinal and transverse configurations. The coherence of the SH responses from the nonmagnetic and magnetic subsystems of the Co-Cu granular films is demonstrated by the MSHG phase measurements (the MSHG interferometry).
Fabrication of Nanostructured Monoclinic Zirconia Ceramics by Colloidal Processing
Authors: Uchikoshi T. , Sakka Y. , Ozawa K. , Hiraga K. 
Published: April 2011

ABSTRACTFabrication of fine-grained monoclinic zirconia ceramics has been attempted from acid and neutral zirconia sols, which have been prepared by different methods. Complete re-dispersion of flocculated particles for the neutral sol is impossible even by changing its pH, while no flocculation is observed for the acid sol. Chloride ions, which are inevitably present in the acid sol, are removed effectively by using anion exchange resin. Consolidation of the sols is performed by the pressure filtration method at 10 MPa, followed by CIP treatment at 400 MPa. It is possible to densify the compacts from both sols to >98% of theoretical density by pressureless sintering in air at 1100 °C. This temperature is lower than that for the monoclinic to tetragonal transformation of pure zirconia. Fine and homogenous-grained microstructures, which have an average grain size of 92 nm, are observed for monoclinic zirconia fabricated from the acid sol. However, more coarse and heterogeneous microstructures are observed for the compact fabricated from the neutral sol.
Producing Clay-Coated Quartz Powders for Semidry Pressing of Wall Ceramics
Authors: Kryukova G.N. , Simonov P.A. , Storozhenko G.I. , Boldyrev G.V. 
Published: April 2011

ABSTRACTThis paper discusses the potential of mechanochemical activation of low grade raw materials with carbonaceous inclusions to achieve high-quality building ceramics. The procedure proposed enabled us to produce clay-coated quartz powders thus facilitating further processing steps of semidry pressing and firing of the bricks, tiles and flagstones.
Applications for Silica-Based Aerogel Products on an Industrial Scale
Authors: Schmidt M. , Schwertfeger F. 
Published: April 2011

ABSTRACTAerogels, nanoporous lightweight materials, were discovered more than 60 years ago. The supercritical manufacturing process and expensive raw materials typically used to produce aerogels prohibited commercialization on an industrial scale. Recently a commercially attractive ambient pressure production process was developed which will allow broader commercialization of silica-aerogel products.Some aerogel products for insulation applications and their preparation are described. Sound insulation properties including a remarkable absorption in the difficult low frequency range was found. In the case of insulation plates performance depends on binder and can be positively influenced by choosing the right binding material.
Numerical Modelling of the Strength of Highly Porous Aerated Autoclaved Concrete
Authors: Schneider Thomas , Schober Georg , Greil Peter 
Published: April 2011

ABSTRACTHighly porous building materials like aerated autoclaved concrete are characterized by low thermal conductivity and high mechanical strength, which both strongly depend on porosity. The influence of porosity distribution on the compressive strength of aerated autoclaved concrete was investigated by using finite element analysis and multiaxial Weibull theory. Calculations of failure probability of microstructures with ordered as well as random pore configurations show a dependence of compressive strength on the Weibull modulus of the matrix material and the size and arrangement of pores. The results of the calculations are compared to experimental data of aerated autoclaved concrete.
Fabrication and Properties of Syntactic Magnesium Foams
Authors: Hartmann M. , Reindel K. , Singer R. F. 
Published: April 2011

ABSTRACTSyntactic magnesium foams which consist of thin-walled hollow alumina spheres embedded in a magnesium matrix were fabricated by infiltrating a three-dimensional array of hollow spheres with a magnesium melt by using a gas pressure-assisted casting technique.The resulting composite contains closed cells of homogeneous and isotropic morphology. The densities of the syntactic magnesium foams were between 1.0 and 1.4 g/cm3. The densities were controlled by variations in the bulk density of the hollow spheres with the volume fraction of spheres kept constant at approximately 63 %.Compressive deformation characteristics of the composites were evaluated with respect to the influence of matrix strength and sphere wall thickness on characteristic variables such as compressive strength, plateau stress and energy absorption efficiency. Differences in the strength of the magnesium-based matrix materials investigated (cp-Mg, AM20, AM50, AZ91) had little influence on the compressive strength of the syntactic foam. However, an increasing relative wall thickness of the hollow ceramic spheres led to a significant strength enhancement. In all cases the ratio between compressive and plateau strength rose with increasing composite strength resulting in decreasing energy absorption efficiency.
Bending Properties of Foamed Aluminum Panels and Sandwiches
Authors: Simančik F. , Kováčik J. , Mináriková N. 
Published: April 2011

ABSTRACTThe foamed panels and sandwiches were prepared by powder metallurgical route using various matrix alloys. The effect of the apparent density, geometry and structure of the foam on its bending stiffhess was studied with respect to the results of the four-point-bending. It has been shown that the modulus of elasticity of the foam cannot be related only to its apparent density, because the distribution of the cell-wall material along the thickness of the foamed panel is not uniform. Therefore the real moment of inertia of the foam's cross-section should be used for the calculation of bending stiffness. This moment can be determined from the square weight of the foamed sample.
Difference between Wafer Temperature and Thermocouple Reading during rapid Thermal Processing
Authors: Borca-Tasciuc T. , Achimov D. A. , Chen G. 
Published: April 2011

ABSTRACTThermocouples are often used as a calibration standard for rapid thermal processing. Although it has been recognized that the thermocouple temperature can be different from the wafer temperature, the magnitude of the temperature difference is difficult to quantify. In this work, we present a simple analytical model to demonstrate the difference between the thermocouple temperature and the true wafer temperature. The results show that a large difference can exist between the thermocouple and the wafer temperature. This is because the optical and thermophysical properties of the thermocouple and the glue material are different from those of the wafer. The model results show that temperature measurement becomes more accurate if fine diameter thermocouple wires with very low emissivity are used.
Rapid Thermal Processes for Future Nanometer MOS Devices
Authors: Hauser John R. 
Published: April 2011

ABSTRACTScaling of MOS devices is projected to continue down to device dimensions of at least 50 nm. However, there are many potential roadblocks to achieving such dimensions and many standard materials and front-end processes which must be significantly changed to achieve these goals. The most important areas for change include (a) gate dielectric materials, (b) gate contact material, (c) source/drain contacting structure and (d) fundamental bulk CMOS structure. These projected changes are reviewed along with possible applications of rapid thermal processing to achieving future nanometer scale MOS devices.
Defect Reduction in Remote Plasma Deposited Silicon Nitride by Post-Deposition Rapid Thermal Annealing
Authors: Lucovsky G. , Parker C. R. , Wu Y. , HAUSER J. R. 
Published: April 2011

ABSTRACTThis paper describes a novel synthesis route for producing defect-free siliclon nitride films that are demonstrated to provide state of the art electrical performance in MOS devices with stacked oxidenitride gate dielectrics in both nmos and pmos devices. High concentrations of bonded hydrogen are introduced into the as-deposited nitride films during a 300°C remote plasma-enhanced deposition, and then the majority of this hydrogen is evolved during a 30 second rapid thermal anneal (RTA) at 900°C. The nitride formed in this way is effectively “defect-free” and qualitatively different from nitride films formed by conventional chemical vapor deposition processes.
A Study of Transistor Optimization in A 0.25 Micron Cmos Flow Using Source/Drain and Silicide Process Modules and Their Interactions
Authors: Vasanth K. , Apte P. , Davis J. , Saxena S. , Burch R. , Rao S. , Mozumder P. K. 
Published: April 2011

ABSTRACTA modular approach to CMOS process development requires an understanding of individual process modules (channel, gate etc.) and their interactions. The reverse short channel effect (RSCE) in NMOS devices is one such interaction between the channel and source/drain (S/D) modules. Similarly the interaction between the S/D and silicide modules affects the contact and gate sheet resistance. This paper presents (a) an investigation of the effects of S/D processing (As and P implant conditions) on the RSCE, (b) effects of S/D and silicide processing on the contact and gate sheet resistance, (c) the use of an integrated system to optimize process modules and their interactions and (d) the validity of the modules and system in process development by obtaining a 4% improvement in drive current of a 0.25 micron NMOS device.
The Two-Step Rapid Thermal Annealing Effect of the Prepatterned A-SI Films
Authors: Park Kee-Chan , Choi Kwon-Young , Lee Min-Cheol , Han Min-Koo , Yoon Chan-Eui 
Published: April 2011

ABSTRACTHydrogenated amorphous silicon (a-Si:H) films which were deposited by plasma enhanced chemical vapor deposition (PECVD) have been recrystallized by the two-step rapid thermal annealing (RTA) employing the halogen lamp. The a-Si:H films evolve hydrogen explosively during the high temperature crystallization step. In result, the recrystallized polycrystalline silicon (poly-Si) films have poor surface morphology. In order to avoid the hydrogen evolution, the films have undergone the dehydrogenation step prior to the crystallization step.Before the RTA process, the active area of thin film transistors (TFT's) was patterned. The prepatterning of the a-Si:H active islands may reduce the thermal damage to the glass substrate during the recrystallization. The computer generated simulation shows the heat propagation from the a-Si:H islands into the glass substrate. We have fabricated the poly-Si TFT's on silicon wafers. The maximum ON/OFF current ratio of the devices was over 10.
Comparative Studies of Pb/Cu(001) by TEM, AFM and STM
Authors: Bocquet Franck , Cohen Camille , Schmaus Didier , Rocher André , Crestou Jacques , Gauthier Sèbastien 
Published: April 2011

AbstractThe same specimen of Pb/Cu grown under Ultra High Vacuum (UHV) conditions has been investigated by Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). We show that the information obtained by these techniques is consistent when comparable, and complementary. In particular, three different morphologies of Pb islands with specific orientation relationship are observed; AFM reveals the faceted shape of the islands; STM permits an accurate determination of the atomic structure of the facets; TEM moir6 patterns reveal that Pb islands are well relaxed.
Fluctuations of Step Edges: Revelations About Atomic Processes Underlying Surface Mass Transport
Authors: Einstein T. L. , Khare S. V. , Pierre-Louis O. 
Published: April 2011

AbstractExperimental advances in recent years make possible quantitative observations of step-edge fluctuations. By applying a capillary-wave analysis to these fluctuations, one can extract characteristic times, from which one learns about the mass-transport mechanisms that underlie the motion as well as the associated kinetic coefficients [1-3]. The latter do not require a priori insight about the microscopic energy barriers and can be applied to situations away from equilibrium. We have studied a large number of limiting cases and, by means of a unified formalism, the crossover between many of these cases[4]. Monte Carlo simulations have been used to corroborate these ideas. We have considered both isolated steps and vicinal surfaces; illustrations will be drawn from noble-metal systems, though semiconductors have also been studied. Attachment asymmetries associated with Ehrlich-Schwoebel barriers play a role in this behavior. We have adapted the formalism for nearly straight steps to nearly circular steps in order to describe the Brownian motion of single-layer clusters of adatoms or vacancies on metal surfaces, again in concert with active experimental activity [3,5]. We are investigating the role of external influences, particularly electromigration, on the fluctuations.
Nucleation of Islands During Epitaxial Growth: Influence of a Second Species
Authors: Ranade Pushkar S. , Chrzan D. C. 
Published: April 2011

AbstractThe theory of the nucleation and growth of islands is maturing rapidly. This advance is driven by the increased availability of experimental data, as well as the need for better control over growth processes. Recently, a number of authors have studied the effects of introducing a second species onto the surface in order to influence the ultimate growth morphology. In some situations, the addition of a second species results in a signficant change (approximately a factor of 1000) in the nucleated island density. The origin of this increase in density has been linked to the anomalous diffusion induced by the presence of the additional species of atoms. In the current paper, this dependence is explored further. In particular, earlier work focused on nucleation and growth in the regime in which the second species is essentially immobile. This constraint is relaxed here, and the subsequent model studied through application of a self-consistent mean-field theory. Predictions for the total island density are presented.
Epitaxy of Thin Ternary Co1−xFexSi2 Silicide Films on SI(111)
Authors: Khouchaf L. , Berling D. , Pierron-Bohnes V. , Pirri C. , Hong S. , Wetzel P. , Gewinner G. , Tuilier M. H. , Lefebvre S. , Cortts R. 
Published: April 2011

AbstractLow-energy electron diffraction, x-ray diffraction, and x-ray absorption techniques are used to investigate the atomic structure of ternary silicides (MSi2, M = Co, Fe). 100 Å thick Co1−xFexSi2 films (with 0 ≤ × ≤ 1) were grown by codeposition onto a Si(111) substrate held at room temperature. The as-deposited films are metallic and adopt an ordered cubic structure of CsCl-type with essentially random vacancies, very similar to that of room-temperature grown FeSi2 and CoSi2 silicides. Upon annealing at 650°C, Fe-rich (x ≥ 0.85) films invariably convert into a semiconducting phase with a structure similar to the orthorhombic β-FeSi2 one. Yet, most interestingly, an almost cubic structure is preserved for x ≤ 0.85. Nevertheless, x-ray diffraction reveals a demixion into a Co rich CaF2-type silicide and a Fe-rich phase with a nearly cubic α-FeSi2 type structure. Extended x-ray absorption fine structure measurements indicate a local environment of Fe atoms similar to that in CsCl-type or α-FeSi2-type structure over the whole 0 < x < 0.85 composition range, showing that Fe does not merely substitute for Co atoms in a perfect CaF2-type CoSi2 structure, even for very low Fe content. In contrast, the local environment of Co atoms is similar to that in CoSi2 for Co-rich ternary compounds. Substantial modifications around Co sites are although observed in Fe richer silicides, suggesting that for x < 0.5, an appreciable amount of Co is incorporated in the α-FeSi2-type silicide phase.
Contribution to Optical Fiber Lifetime Modelling in Very Harsh Installation and Environment Conditions:Influence of the Temperature and pH on Optical Fiber Mechanical Behaviour.
Authors: Evanno Noëlla , Poulain Marcel , Gouronnec Alain 
Published: April 2011

AbstractToday, during their use, optical fibers are subject to harsher installation and environmental conditions. So to evaluate optical fiber lifetime with higher precision, it is necessary to study the mechanical behaviour of optical fibers in extreme conditions : high stress and harsh environment.This paper presents the results of static bending tests in distilled water at temperatures between 20°C and 70°C and in buffer solutions with a pH between 4 and 9.The stresses applied on optical fiber were between 3 and 3.5 GPa.We observed a dependence of the failure time on temperature. This dependence can be described by the Arrhenius model, where the activation energy is one of the main parameters. The n-value seems also to change regularly with temperature. The results obtained in buffer solutions show that the pH influence on optical fiber strength may depend on coating characteristics.
Metallization of Silica Optical Fibers
Authors: Filas Robert W. 
Published: April 2011

AbstractA review is presented of metallization processes of silica optical fiber. Fiber strengths and fatigue data are summarized and compared for liquid metal freezing, chemical vapor deposition, sputtering, electroless and electrolytic coatings. Both continuous in-line and termination-only processes are considered. Details of an electroless Ni-P plating process are presented which can be used to prepare fiber ends for soldering into hermetic packages.
Silicone Optical Attenuators
Authors: Lambert W. R. , Filas R. W. , King W. W. 
Published: April 2011

AbstractLucent Technologies manufactures and markets a family of SC and ST singlemode optical attenuator products which are low cost and easy to use. The attenuator elements are available in the attenuation range of 3 to 20 dB and are housed in buildout barrels which snap into companion buildout blocks to form complete optical couplings. The attenuator element is a 0.086-inch diameter thermoplastic material which, depending upon the attenuation level, has a thickness from 0.006 to 0.065 inches. In order to meet the full range of customer performance requirements, the attenuator element should not creep at temperatures up to 80°C and exhibit a reflection of less than -55 dB at optical telecommunication wavelengths. Commercially available thermoplastic materials cannot meet these requirements.
Visible and Infrared Rare-Earth Activated Electroluminescence From Erbium Doped GaN
Authors: Garter M. , Birkhahn R. , Steckl A. J. , Scofield J. 
Published: April 2011

AbstractRoom temperature visible and IR light electroluminescence (EL) has been obtained from Er-doped GaN Schottky barrier diodes. The GaN was grown by molecular beam epitaxy on Si substrates using solid sources (for Ga and Er) and a plasma source for N2. Transparent contacts utilizing indium tin oxide were employed. Strong green light emission was observed under reverse bias due to electron impact excitation of the Er atoms. Weaker emission was present under forward bias. The emission spectrum consists of two narrow green lines at 537 and 558 nm and minor peaks at 413, 461, 665, and 706 nm. There is also emission at 1000 nm and 1540 nm in the IR. The green emission lines have been identified as Er transitions from the 2H11/2 and 4S3/2 levels to the 4I15/2 ground state. The IR emission lines have been identified as transitions from the 4I13/2 and 4I13/2 levels to the 4I15/2 ground state. EL intensity for visible and IR light has a sub-unity power law dependence on bias current. An external quantum efficiency of 0.1% has also been demonstrated under a reverse bias current of 3.85 mA.
Defect Complexes and Non-Equilibrium Processes Underlying the P-Type Doping of GaN
Authors: Reboredo Fernando A. , Pantelides Sokrates T. 
Published: April 2011

AbstractIt is well known that hydrogen plays a key role in p-type doping of GaN. It is believed that H passivates substitutional Mg during growth by forming a Mgs-N-Hi complex; in subsequent annealing, H is removed, resulting in p-type doping. Several open questions have remained, however, such as experimental evidence for other complexes involving Mg and H and difficulties in accounting for the relatively high-temperature anneal needed to remove H. We present first principles calculations in terms of which we show that the doping process is in fact significantly more complex. In particular, interstitial Mg plays a major role in limiting p-type doping. Overall, several substitutional/interstitial complexes form and can bind H, with vibrational frequencies that account for hitherto unidentified observed lines. We predict that these defects, which limit doping efficiency, can be eliminated by annealing in an atmosphere of H and N prior to the final anneal that removes H.
Interface Effects on the Persistent Photoconductivity in Thin GaN and AlGaN Films
Authors: Seifert O. P. , Kirfel O. , Munzel M. , Hirsch M. T. , Parisi J. , Kelly M. , Ambacher O. , Stutzmann M. 
Published: April 2011

AbstractThin films of GaN and its alloy AlGaN are investigated with respect to their properties of the persistent photoconductivity (PPC). In this work, we show that the film-substrate interface plays an important role for the metastable electrical effect. Strongly absorbed bandgap light causes an increase of photoconductivity which is about one order of magnitude higher when the sample is illuminated from the substrate side near the interface than from the growth side. To access the interface properties at the substrate, we use temperature-dependent Hall effect measurements. The smallest PPC effect was observed for the GaN film with the best interface properties grown on SiC.