bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Additive Constraint on the Morphological and Mechanical Properties of Triblock Copolymer Blends
Authors: Kane L. , Norman D. A. , White S. A. , Spontak R. J. 
Published: April 2011

ABSTRACTWhile numerous studies have addressed the morphological characteristics of diblock copolymer blends either with a second copolymer or a parent homopolymer, relatively few have examined comparable blends containing a triblock copolymer. In this study, we investigate the role of mid-block bridging on the morphological and physical characteristics of blends composed of a poly(styrene-b-isoprene-b-styrene) (SIS) triblock copolymer with either an unconstrained homo-polyisoprene (hI) or an end-grafted SI diblock copolymer. Blend compositions and molecular weights of the hi, as well as the I-block of the copolymer, have all been systematically varied to elucidate the effect of additive constraint on the extent of nonideal intramicrodomain mixing. Blend morphologies are characterized using transmission electron microscopy, while blend properties have been measured by dynamic mechanical analysis.
Determination of Degree of Polymerization of Cellulose in Ligneous Papers
Authors: Kaminska E. 
Published: April 2011

ABSTRACTIn the past, many attempts have been made to determine the degree of polymerization (DP) of cellulose in ligneous pulps or papers. Frequently, the methods employed caused severe depolymerization of the cellulose.The present paper provides a detailed procedure of DP determination of cellulose for both lignin-free and ligneous papers. The proposed method is based on viscosity measurements of cadoxen solutions of cellulose. Prior to dissolution in cadoxen, ligneous samples are partially delignified by a modified chlorite method, under conditions preventing any substantial depolymerization of cellulose. Results of preliminary experiments carried out on groundwood newsprint papers provide strong evidence of reliability of DP values so determined.
Point Defects, Diffusion and Gettering in Silicon
Authors: Gösele U. , Conrad D. , Werner P. , Tong Q.-Y. , Gafiteanu R. , Tan T. Y. 
Published: April 2011

ABSTRACTThe status of our knowledge on intrinsic point defects and diffusion mechanisms is reviewed. Special attention is given to the question of the possible role of carbon in influencing effective diffusivities of intrinsic point defects and the resulting consequences for the values of vacancy and self-interstitial thermal equilibrium concentrations and diffusivities. It is pointed out that we might have to deal with the unfortunate situation that the effective diffusivities of intrinsic point defects might be influenced already by a carbon concentration which is below the detection limit and therefore not amenable to measurement and control. Whereas dopant diffusion processes have been modeled and simulated for a long time the first attempts to quantitatively simulate various gettering processes have just started as will be described in the paper. Finally, the subject of microcrack formation in hydrogen implanted silicon will be dealt with as used for the so-called “smart-cut” process for fabricating silicon-on-insulator (SOI) substrates with thin and uniform silicon layers by wafer bonding. Presently no quantitative treatment of this fascinating hydrogen agglomeration phenomenon is available.
Point Defect Injection Kinetics by N2O Oxidation of Silicon
Authors: Tsamis C. , Kouvatsos D. N. , Tsoukalas D. 
Published: April 2011

ABSTRACTThe influence of N2O oxidation of silicon on the kinetics of point defects at high temperatures is investigated. Oxidation Stacking Faults (OSF) are used to monitor the interstitials that are generated during the oxidation process. We show that at high temperatures (1050°-1150°C) the supersaturation of self-interstitials in the silicon substrate is enhanced when oxidation is performed in an N2O ambient compared to 100% dry oxidation. This behavior is attributed to the presence of nitrogen at the oxidizing interface. However, at lower temperatures this phenomenon is reversed and oxidation in N2O ambient leads to reduced supersaturation ratios.
Formation and Binding Energies of Vacancy Clusters in Silicon
Authors: Colombo L. , Bongiorno A. , Diaz De La Rubia T. 
Published: April 2011

ABSTRACTWe critically readdress the problem of vacancy clustering in silicon by perform large-scale tight-binding molecular dynamics simulations. We also compare the results of this quantum-mechanical approach to the widely used model-potential molecular dynamics scheme based on the Tersoff and Stillinger-Weber interatomic potentials.
Effect of Annealing Under Uniform Stress on Photoluminescence, Electrical and Structural Properties of Silicon
Authors: Misiuk A. , Karwasz G. P. , Cazzanelli M. , Jung W. , Pavesi L. 
Published: April 2011

ABSTRACTEffect of increased pressure (up to 1.5GPa) during annealing of Cz-Si on creation of thermal donors (at 720 - 1000K) and visible luminescence (peaking at 1.7- 2.2eV for samples annealed at up to 1420K) is reported. The observed phenomena are related to stress - stimulated oxygen clustering / precipitation in Cz-Si resulting in creation of specific defects.
The Effect of Oxygen on The Electrical Activation and Diffusion of Ion-Implanted Boron
Authors: Kyllesbech Larsen K. , Stoik P. A. , Privitera V. , van Berkum J. G. M. , de Boer W. B. , Marinino G. , Cowern N. E. B. , Huizing H. G. A. 
Published: April 2011

ABSTRACTTransient enhanced diffusion (TED) and electrical activation (EA) of ion-implanted boron during rapid thermal annealing has been investigated using three types of boron doped p-type Si (100) substrates: (a) Cz 20 Ωcm, (b) 3 μm thick 20 Ωcm epitaxial Si layer (epi-layer) grown on a 20 Ωcm Cz substrate, and (c) 3 μm thick 20 Ωcm epi-layer grown on a 5 mΩcin Fz substrate. The level of oxygen is known to decrease from material type (a) to (c). The samples were implanted with 20 keV, 5×1013cm−2boron and subjected to rapid thermal annealing (RTA) at various temperatures and times. The EA and TED were studied using spreading resistance profiling (SRP) and secondary ion mass spectrometry (SIMS), respectively. Although the amount of TED is almost identical for the three substrates, the EA is found to be significantly higher in the epi-layers compared to Cz substrates. It is speculated that the trapping of vacancies by oxygen in the ion-damaged region leads to an increase in the interstitial supersaturation during annealing, which then results in enhanced boron clustering and reduced electrical activation in the peak of the implanted profile.
Chemical and Electrochemical Staining for Two-Dimensional Dopant Concentration Profiling on ULSI Silicon Devices
Authors: Spinella C. 
Published: April 2011

ABSTRACTWe discuss the sample preparation technique for the two-dimensional dopant concentration profiling in silicon based on chemical staining and transmission electron microscopy analysis. The capability of characterizing ULSI silicon devices is demonstrated by showing an example of failure analysis performed on a high speed bipolar transistor. The high spatial resolution of the technique allows to reveal many details which are not detectable by other techniques. The limitations of this method concern the impossibility to simultaneously delineate n and p-type regions on the same sample, and the need to have a p+n junction for delineating a boron profile with an acceptable sensitivity. We demonstrate that these limitations can be overcome by developing a novel electrochemical staining procedure based on anodic oxidation of silicon.
Monte Carlo simulation of Boron diffusion during low energy implantation and high temperature annealing
Authors: Caturla M.-J. , Diaz de la Rubia T. , Zhu J. , Johnson M. 
Published: April 2011

ABSTRACTWe use a kinetic Monte Carlo model to simulate the implantation of low energy Boron in Silicon, from 0.5 to 1 keV, at high doses, 1015 ions/cm2. The damage produced by each ion is calculated using UT-Marlowe, based on a binary collision approximation. During implantation at room temperature,, silicon self-interstitials, vacancies and boron interstitials are allowed to migrate and interact. The diffusion kinetics of these defects and dopants has been obtained by ab initio calculations as well as Stillinger Weber molecular dynamics. Clustering of both self-interstitials, vacancies and boron atoms is included. We also model the diffusion of the implanted dopants after a high temperature annealing in order to understand the transient enhanced diffusion (TED) phenomenon. We observe two different stages of TED During the first stage vacancies are present in the lattice together with interstitials and the diffusion enhancement is small. The second stage starts after all the vacancies disappear and gives rise to most of the final TED.
Effect of End-of-Range Defects, Arsenic Clustering and Precipitation on Transient Enhanced Diffusion in As+ Implanted Si
Authors: Krishnamoorthy V. , Venables D. , Moeller K. , Jones K. S. , Jackson J. 
Published: April 2011

ABSTRACT(001) CZ silicon wafers were implanted with As at lOOkeV to a dose of 1×1015/cm2. The implant was amorphizing in nature and the peak As concentration was below the As clustering threshold. Subsequently, a second As+or Ge+ implant at 30keV at doses of 2×1015/cm2, 5×1015/cm2 and 1×1016/cm2 were performed, respectively, into the as-implanted samples. The samples with a double arsenic implant induce As clustering at the lower doses and As precipitation at the highest dose at the projected range. However, the samples with the Ge do not induce clustering or precipitation. The samples were annealed at 700°C for various times to regrow the amorphous layer and to cause enhanced arsenic diffusion beyond the end-of range region. These samples wereanalyzed by SIMS and TEM. The difference in the defect evolution at the end-of-range region and TED beyond the end-of-range region between the As and Ge implanted samples was used to isolate the effects of As clustering and precipitation.
Nucleation and Growth of {113} Defects and {111} Dislocation Loops Insilicon-Implanted Selicon
Authors: Pan G. Z. , Tu K. N. 
Published: April 2011

ABSTRACTPlan-view and cross-sectional transmission electron microscopy have been used to study the microstructural characterization of the nucleation and growth behavior of {113} rodlike defects, as well as their correlation with {111} dislocation loops in silicon amorphized with 50 keV, 36×1014 Si/cm2, 8.0 mAand annealed by rapid thermal anneals at temperatures from 500 °C to 1100 °C for various times. We found that the nucleations of the {113} rodlike defects and {111} dislocation loops are two separate processes. At the beginning of anneals, excess interstitials accumulate and form circular interstitial clusters at the preamorphous/crystalline interface at as low as 600 °C for 1 s. Then these interstitial clusters grow along the <110> direction to form {113} rodlike defects. Later, while the {113} defects have begun to grow and/or dissolve into matrix, the {111} faulted Frank dislocation loops start to form. We also found that the initial interstitial clusters prefer to grow along the <110>directions inclined to the implantation surface.
Self-Diffusion as A Limiting Factor of a-SiGe Crystallization
Authors: Edelman F. , Raz T. , Komem Y. , Werner P. , Beyer W. , Butz R. , Zeindl H. , Zaumseil P. 
Published: April 2011

ABSTRACTHighly doped (∼1018 to 1021cm−3) polycrystalline Si1-xGex films, crystallized from amorphous (a) state at relative low temperatures, are prospective materials in a variety of applications, such as liquid-crystal displays, solar cells and integrated thermoelectric sensors on large-area glass substrates. Since the nature of the grains in the crystallized film defines properties such as carrier mobility, the nucleation and growth process of the a-SiGe films is of fundamental interest. We have studied the crystallization of undoped and highly doped (B or Ga) amorphous SiGe films. The films were deposited by RFCVD or molecular beam on oxidized (001)Si and for TEM study on cleaved NaCl. The incubation time and grain growth rate were studied by means of in situ TEM using a heating stage. The crystallization process in undoped SiGe followed Avrami relationship. An average grain size between 0.1 and 2μm was observed. However, the highly p-doped (with B or Ga) SiGe films crystallized to a stable nanocrystalline structure (grain size <10nm). The process of the a-SiGe crystallization is explained on the basis of self-diffusion. During the first stage, the nucleation of crystals is accompanied with nonequilibrium vacancy generation at the amorphous/crystalline interface. During the second stage, the growth of crystals takes place by vacancy outdiffusion which is hindered by B and Ga interaction with vacancies.
Anomalous Diffusion of Ultra low Energy Boron Implants in Silicon
Authors: Webb R. P. , Foad M A , Gwilliam R M , Knights A P , Thomas G. 
Published: April 2011

ABSTRACTUltra low energy boron implants (0.2 to 3 keV) have been carried out on Si (100) at doses between 1×1014cm−2 and 1×1015cm−2 using xRLEAP. The samples were annealed at temperatures between 900°C and 1050°C. The atomic profiles of these samples was measured using SIMS. Monte Carlo and diffusion simulations were performed using the SSupreme code. Comparisons between the simulations and experimental measurements show interesting differences these are discussed.
High Silicon Self-Interstitial Diffusivity as Revealed by Lithium Ion Drifting
Authors: Knowlton W. B. , Walton J. T. , Wong Y. K. , Mason I. A. , Haller E. E. 
Published: April 2011

ABSTRACTWe report on the use of lithium ion (Li+) drifting1 as a sensitive means to study Si self-interstitial (SiI) diffusion.2 Li+ properties in silicon are well known from extensive ion drift studies and Li+ interactions with dopants and point defects.3 We have used this low temperature (∼100°C) technique in combination with Si1 injection from oxides to delineate, identify and eliminate D defects4 in certain p-type floating zone (FZ) Si single crystals.5 Our results suggest Si1 diffusion occurs to a depth of at least 10 mm into the bulk during phosphorus (P) diffusion with oxidation (i.e., POCI3 process) at 950°C for 100 min. Process modeling of this lower bound SiI diffusion using SUPREM-IV9 results in a Sii diffusivity of 3.5×10−6 cm2/s at 950°C.
An Examination of the Crystalline Quality of 200mm Diameter Silicon Substrates using X-ray Topography
Authors: Curley J. , McNally P. J. , Reader A. , Tuomi T. , Taskinen M. , Rantamäki R. , Danilewsky A. , Schropp B. 
Published: April 2011

ABSTRACTThe continued decrease in critical dimensions and increasing integration levels in Si CMOS technology is imposing ever tighter constraints on quality control parameters for the IC manufacturing industry. One very important issue is the need to ensure a uniform, high quality Si substrate, i.e. minimise defect/dislocation densities and eliminate strain distributions in the starting wafer material. A comprehensive Synchrotron X-Ray Topography (SXRT) study was applied to commercially supplied 200mm diameter Si wafers. These wafers, which all included a surface Si epilayer growth were supplied from manufacturers from around the globe. The study revealed not only differences in the overall quality of the wafers, but also differences in the quality of the individual Silicon epilayers and substrates. In all wafers the substrate quality varied dramatically with position across the wafer, as measured by the distribution of oxygen precipitates and stacking faults in the wafer. This distribution also varied significantly from manufacturer to manufacturer. The strain fields induced by the growth of lightly doped Si epilayers were also observed to qualitatively vary with location on a wafer, together with (as expected) thickness of the epilayers. The results clearly indicate that optimal quality control for such commercial wafers has not yet been achieved.
Twinning Mechanism in PrCo2Cx Magnetic Phase
Authors: Wu Lijun , Bian Weimin , Zhu Yimei 
Published: April 2011

ABSTRACTA magnetic rhombohedral PrCo2Cx (x=0.05∼0.25) phase (space group R3m), which is heavily twinned along the {110} and {211} planes, was identified. The twinning mechanism was explored by analyzing the reduction of crystal symmetry due to the cubic-rhombohedral phase transformation. The origin of the twinning and the formation of four twin variants were attributed to the insertion of carbon interstitials into Co4 tetrahedrons along the 3 axis in the rhombohedral lattice, which corresponds to one of the four equivalent <111> axes of its parent PrCo2 cubic-lattice.
Origins of Contrast in Near-Field Scanning Optical Microscopy Photovoltage Images of Cu(In,Ga)Se2 Solar Cells
Authors: McDaniel A. A. , Hsu J. W. P. 
Published: April 2011

ABSTRACTPhotovoltage images of Cu(In,Ga)Se2 solar cells taken using near-field scanning optical microscopy (NSOM) show reduction of photoresponse along grain boundaries. Two factors might be responsible for this contrast. The first is that the topographic changes associated with the grains could cause the NSOM tip to move further from the sample, resulting in a reduction in photoresponse. The second possibility is that the contrast is due to real physical properties of the sample, e.g. higher recombination velocities near grain boundaries. We show convincing evidence that the major contribution to the contrast in the photovoltage images is due to the latter.
Preparation and Residual Stress Characterisation of Polycrystalline Silicon Germanium Films Grown by Atmospheric Pressure Chemical Vapour Deposition
Authors: Fiorini P. , Sedky S. , Caymax M. , Baert C. 
Published: April 2011

ABSTRACTPolycrystalline silicon-germanium alloys (poly-SiGe) are deposited by chemical vapour deposition at atmospheric and reduced pressure. The stress, as well as its profile along the growth direction, are measured. Depending on the deposition pressure the stress can be compressive or tensile, the profile of the stress is in both cases rather uniform. The behaviour of the stress as a function of annealing temperature is also investigated. Films which are compressive as grown can be made tensile by annealing, films which are tensile as grown remains tensile even after high temperature annealing.
Electromigration and 1/f Noise in Single-Crystalline, Bamboo and Polycrystalline Al Lines
Authors: Van Den Homberg Marc J.C. , Alkemade P.F.A. , Verbruggen A.H. , Dirks A.G. , Ochs E. , Radelaar S. 
Published: April 2011

ABSTRACTThe relation between electromigration and microstracture for three types of Al lines with different microstructures has been studied. The lines were made by recrystallization of Al in a SiO2 groove pattern. They were either truly bamboo with grains of on average 3 μm long or distorted (i.e. with dislocations) single-crystals. In addition, conventional, polycrystalline Al lines with grains of on average 230 nm were made. The lines were lifetime-tested (200 °C,j=2, 5 and 8 MA/cm2) and subjected to 1/f noise measurements (from 200 to 500 K).The bamboo and single-crystalline Al lines showed the same, although weak, 1/f noise. This observation demonstrates that other mechanisms than thermal motion of atoms at grain boundaries can cause noise. It is suggested that dislocations are the sources for noise in our samples. The measured activation energy (0.8 eV) is in agreement with the activation energy for pipe diffusion along dislocation lines.The lifetime-tests showed significantly higher times to failure for the single-crystalline and bamboo lines as compared to polycrystalline lines. Preliminary results indicate slightly higher lifetimes for the bamboo than for the single-crystalline lines. It is concluded that interface diffusion is the main mechanism for electromigration in truly bamboo or single-crystalline lines. Our measurements demonstrated that dislocations are important in the formation of 1/f noise and interfaces in the formation of electromigration damage.
The Fiber Texture Growth and the Surface Roughness of ZNO Thin Films
Authors: Anna Selvan J. A. , Keppner H. , Kroll U. , Cuperus J. , Shah A. , Adatte T. , Randall N. 
Published: April 2011

ABSTRACTZinc Oxide (ZnO) is one of the important Transparent Conducting Oxides (TCO) for thin film photovoltaic cells with respect to performance and cost reduction. When used in photovoltaic cells, the surface roughness of ZnO is required in order to increase the amount of light going inside the cells (Light Trapping). In this paper we present the surface morphology in connection with the fiber texture of ZnO films at different experimental conditions. The structural properties of the ZnO films grown by the method of radio frequency sputtering and Chemical Vapour Deposition (CVD) with the special effort to make surface roughness (Surface Texturing) are presented. The influence of the control over the fiber texture, surface mobility of the adatoms and the dissociation of water vapour during growth are explained.
Evolution of Texture and Microstructure in Rough Polycrystalline Silicon for Advanced Dram Applications
Authors: Banerjee A. , Wise R. L. , Crenshaw D. L. , Khamankar R. B. , Edwards Hal 
Published: April 2011

ABSTRACTThis study investigates the morphology, roughness and electrical performance of rough polysilicon films deposited by LPCVD process. The deposition duration was varied over a broad range to study the evolution of microstructural texture in terms of nuclei formation, growth and grain coalescence. The area enhancement factor (AEF) of rough polysilicon film, expressed as the ratio of cell capacitance incorporating textured film to that of a smooth polysilicon film is observed to range from 1.4 to 2.4 for the above conditions. It is observed that the AEF shows a strong dependence on the microstructural texture and correlates with the surface roughness. A model for electrical AEF based on grain morphology attributes from AFM is included. The dependence of rough polysilicon nucleus cluster density on silane flow rate and deposition temperature is also presented.
Growth and Structure of Ti2O3and TiO2Thin Films on (0001) α-Al2O3Substrates
Authors: Wagner T. , Agarwal M. 
Published: April 2011

ABSTRACTTitanium oxide thin films were grown at different temperatures on (0001) α-Al2O3substrates by molecular beam epitaxy (MBE). The films grown at room temperature were amorphous. Annealing at 1223K of 6 nm thick films led to the formation of TiO2with an epitaxial orientation relationship (100)<001>TiO2∥ (0001)<01101>Al2O3with the substrate. However, on similar heat treatment, thicker 100 nm films formed polycrystalline TiO2. At a deposition temperature of 1223K epitaxial Ti2O3films with orientation relationship (0001)<2110>Ti2O3∥ (0001)<21101>Al2O3were formed. The lattice mismatch between Ti2O3and α-Al2O3was accomodated by a regular arrangement of misfit dislocations at the Ti2O3/α-Al2O3interface. By comparing the microstructural evolution of the annealed films with that of those films grown at high temperature, mechanisms governing grain growth in polycrystalline titanium oxide films were discussed.
Electrical Characterization of Ultra-Thin Oxides Grown on
Silicon Surfaces Cleaned in Ultra-High Vacuum
Authors: Petersen C. L. , Grey F. 
Published: April 2011

ABSTRACTWe have investigated the oxidation of clean reconstructed silicon surfaces
in-situ using a fourpoint probe technique. The measured conductance
variations, on Si(111) and Si(100) surfaces as a function of oxygen exposure
are markedly different. On Si(100) surfaces, the conductance displays a
rapid fall during the first 100 L exposure to O2, followed by a
slower steady decrease at higher oxygen exposures. This behavior is similar
for both n-type arid p-type silicon. The conductance of Si(111) surfaces
increases significantly at the onset of the oxidation. This conductance
increase is found on both n-type and p-type Si(111) samples. We interpret
this as being due to the molecular precursor which is known to form in the
peroxy bridge position.