bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geophysical Applications for Deep Geological Repository Studies in Plutonic Rocks of Canada
Authors: Lodha Ganpat S. , Serzu Mulugeta H. , Kozak Ed T. , Everitt Richard A. , Tomsons Dzintars K. , Hayles John G. 
Published: April 2011

ABSTRACTAtomic Energy of Canada Limited (AECL) has been conducting detailed geological, geophysical and geotechnical investigations in plutonic rocks at several research areas. The main focus of the work was on developing and testing site evaluation and site characterization methods to investigate progressively smaller volumes of plutonic rocks in greater details. In this process extremely detailed airborne, surface and borehole geophysical surveys were done to identify fractures and understand groundwater flow conditions. A brief review of geophysical methods, which demonstrate the area scale, site scale and vault scale characterization techniques has been included in this paper. The boreholes in the Whiteshell Research Area (WRA) of Lac du Bonnet Batholith and at its Underground Research Laboratory (URL) excavated to 420 m depth have provided extensive opportunities to develop and test these methods. One example of geophysical surveys associated with the Moderately Fractured Rock (MFR) experiment at 240 Level is discussed in some length.
Advances in Classifications for Structural Modelling of the Olkiluoto Site
Authors: Vaittinen Tiina , Ahokas Henry , Hellä Pirjo , Saksa Pauli , Oy Fintact 
Published: April 2011

ABSTRACTThe site characterization for the construction of the repository of spent nuclear fuel is carried out at Olkiluoto in Finland. The results of geological, geophysical, and hydrogeological investigations are integrated in a bedrock model to describe rock types, fractured zones and potential hydraulic connections. In modelling it is essential to determine structures important for construction of underground facilities. This question encompasses objectives and scale of the modelling. Important parameters in structural modelling are fracture frequency and hydraulic conductivity. The definitions need to be evaluated site-specific, because the geological circumstances control the properties of structures. An important issue is the possible existence of a boundary zone close to structures.
Diffusion and Migration of Ions in Sedimentary Rock Matrix: Effects of Ionic Strength and Tracer Concentration on Diffusion of Cs+ ions in Sandstone
Authors: Sato Haruo 
Published: April 2011

ABSTRACTIn-diffusion experiments for Cs+ and I− in sandstone were performed as a function of ionic strength ([NaCl]=0.01, 0.51M) and tracer concentration ([CsI]=7.5E-5, 1.5E-2M) together with the measurements of the physical and chemical properties of sandstone, and apparent diffusivities (Da) for Cs+ were obtained. The obtained Da-values for Cs+ scarcely depended on [NaCl], but increased with increasing [Cs+]. This trend is consistent with that of rock capacity factors (α), indicating that distribution coefficient (Kd) onto sandstone and effective diffusivity scarcely depend on [NaCl]. The concentration profiles of I− were all in already breakthrough. Although this indicates that I− diffusion is faster than that of Cs+, the concentration profiles of I− may have been lower than those for blank samples, judging synthetically from the correlations between α-values and the concentration profiles of Cs+ and from the concentration profiles of I− in the blank samples. Finally, the effects of [Cs+] and[NaCl] on Kd/-values for Cs+ were discussed from the viewpoint of adsorption by ion exchange and electrostatic attraction. The kd-values were considered to be combined sorption by both reactions.
Sorption of Caesium on Commercial Magnetite with low Silica Content: Experimental and Modelling
Authors: Rovira Miquel , Pablo Joan de , Casas Ignasi , Giménez Javier , Clarens Frederic 
Published: April 2011

ABSTRACTInteraction of Cs on commercial magnetite has been studied under different experimental conditions at high solid/liquid ratios. At pH 8.2 the Freundlich isotherm was able to describe an important range of the experimental data and at high Cs concentration surface precipitation was found likely to occur. Special attention has been given to silica, present in the system as an impurity of magnetite, since it plays an important role on the sorption mechanism in which a ternary complex magnetite-Si-Cs is formed.
About the Luminescence Mechanisms of Composite a-Si:nc-Si System Obtained by Ion-Beam Amorphization in the Wide Dose Region
Authors: Tetelbaum David I. , Ezhevskii Alexander A. , Mikhaylov Alexey N. , Lebedev Mikhail Yu. , Mendeleva Yuliya A. , Ershov Roman G. , Morozov Sergey V. 
Published: April 2011

ABSTRACTRed/near-infrared photoluminescence (PL) of silicon irradiated by ions for wide dose range is investigated. The results are presented obtained for doses near amorphization threshold, where PL is associated with the formation of composite structure composed of nanocrystals (quantum dots) embedded into amorphized matrix and for doses that are strongly larger than amorphization threshold. The PL in this case is caused by formation of nanocrystals due to recrystallization of amorphous layer and penetration of stresses behind the border of this layer.
Fabrication and Characterization of Hydrogenated Amorphous Silicon Bipolar Thin Film Transistor (B-TFT)
Authors: Kuo Yue , Lei Yu , Nominanda Helinda 
Published: April 2011

ABSTRACTThe conventional a-Si:H thin film transistor (TFT) is a field effect transistor (FET), which has disadvantages of a low operation speed and a small current driving capability. To achieve a higher speed and larger current driving capability, a potential solution is to fabricate the a-Si:H-based bipolar thin film transistor (B-TFT). In this study, a-Si:H p-i-n junctions were prepared and studied in order to determine the proper layer thickness for good junction behaviors. B-TFTs composed of a stacked structure of n+/i/p/i/n+ were then fabricated. The complete B-TFT was made using plasma enhanced chemical vapor deposition (PECVD) to deposit all doped and undoped a-Si:H layers and SiNx dielectrics at 250°C. Reactive ion etching (RIE) and wet etching methods were used to define base and emitter regions and contacts. The I-V characteristics of the complete B-TFT were investigated. The common-emitter current gain is 3∼6, which is larger than the literature report of 2∼3. In addition, a collector current larger than the literature value was obtained. A significant current noise was observed, which may be contributed to the high series resistance of the base layer and defective junction interfaces. In this paper, process and structure influences on the a-Si:H junction and B-TFT performances are discussed.
Bottom-Gate TFTs with Channel Layer Grown by Pulsed PECVD Technique
Authors: Grant David J. , Lee Czang-Ho , Nathan Arokia , Das Ujjwal K. , Madan Arun 
Published: April 2011

ABSTRACTIn this paper, we report on nc-Si:H thin films deposited by the pulsed PECVD technique at a temperature of 150C and TFTs made using this material. RF power and silane flow rate were varied in order to study the effect of different levels of crystallinity on the film. Electrical conductivity, Hall mobility, optical transmittance, and Raman backscattering were measured on films of two different thicknesses. From the Raman data we see that the 50 nm films with hydrogen dilution are mostly amorphous, indicating the presence of a thick incubation layer. The values obtained for the conductivity, mobility, and optical gap varied depending on the processing conditions and these results are discussed. Bottom-gate TFTs were fabricated using a pulsed PECVD channel layer and a SiN gate dielectric. The TFTs' extracted parameters are msat μsat ≤ 0.38 cm2=(V s), Vt,sat ≥7:3 V, Ion/off >106, and S < 1 V/decade. The TFT performance and material properties are presented and discussed.
Microstructure Evolution with Thickness and Hydrogen Dilution Profile in Microcrystalline Silicon Solar Cells
Authors: Yan Baojie , Yue Guozhen , Yang Jeffrey , Guha Subhendu , Williamson D. L. , Han Daxing , Jiang Chun-Sheng 
Published: April 2011

ABSTRACTHydrogenated microcrystalline silicon (m c-Si:H) solar cells with different thicknesses were deposited on specular stainless steel substrates and on textured Ag/ZnO back reflectors using RF and modified very high frequency glow discharge at various deposition rates. Raman spectra and X-ray diffraction patterns exhibit a significant increase of microcrystalline volume fraction and in grain size with film thickness. Atomic force microscopy reveals an increase in the size of microstructural features and the surface roughness with increasing thickness. Based on these results, we believe that the increase of the microcrystalline phase with thickness is the main reason for the deterioration of cell performance with the thickness of the intrinsic layer. To overcome this problem, we have developed a procedure of varying the hydrogen dilution ratio during deposition. Using this method, we have been successful in controlling the microstructure evolution and achieved an initial active-area efficiency of 8.4% for a c-Si:H single-junction solar cell, and 13.6% for an a-Si:H/a-SiGe:H/m c-Si:H triple-junction solar cell.
Development of transparent conductive oxide materials for improved back reflector performance for amorphous silicon based solar cells
Authors: Jones Scott J. , Tsu David , Liu Tongyu , Steele Jeff , Capangpangan Rey , Izu Masat 
Published: April 2011

ABSTRACTA new back reflector comprised of an Al/(multi-layered stack)/ZnO structure is being developed to replace Al/ZnO used in manufacturing and boost conversion efficiencies with improved back reflector performance. Use of the multi-layered stack should lead to improved reflectivity which will in turn improve solar cell currents and efficiencies. The results from studies of different transparent conductive oxides (TCOs) which comprise the multi-layered stack are reported with emphasis on ZnO alloys. Alloying with Si or MgF2 and using moderately high substrate temperatures, TCOs with low indices of refraction between 1.6 and 1.7 have been fabricated. The Si, Mg and F contents for these alloys were near 14, 12 and 33 at.%. Structural analysis demonstrates that alloys with MgF2 have smother surfaces and finer morphologies than those for ZnO. The expected high values for multi-layered structures with these alloys have yet to be achieved but this is likely due to properties of layers in the structure other than the ZnO alloys which have yet to be fully optimized.
Transient and modulated photoconductivity in microcrystalline silicon
Authors: Brüggemann R. , Longeaud C. , Kleider J.P. 
Published: April 2011

ABSTRACTWe report on transient and modulated photoconductivity experiments with undoped michrystalline silicon in which access to density-of-states information is limited because the Fermi level results in occupancy of localised states in the energy range which is scanned. Simulation results show that a defect peak will be masked if most of the distribution is occupied because of the Fermi level position and the density-of-states determined from the experimental data is not an image of the true distribution. Another difficulty with obtaining reliable density-of-states distributions in microcrystalline silicon is the metastability of samples with respect ot adsorption of gases. If dark-conductivity changes are large upon heat treatment in vacuum, the modulated and transient photocurrent response are also affected to a large degree and the density-of-states profiles apart form being influenced by the Fermi level position thus also depend on the thermal history of the sample.
Enhanced Boron Diffusion in Amorphous Silicon
Authors: Jacques J.M. , Burbure N. , Jones K.S. , Law M.E. , Robertson L.S. , Downey D.F. , Rubin L.M. , Bennett J. , Beebe M. , Klimov M. 
Published: April 2011

ABSTRACTIn prior works, we demonstrated the phenomenon of fluorine-enhanced boron diffusion within self-amorphized silicon. Present studies address the process dependencies of low temperature boron motion within ion implanted materials utilizing a germanium amorphization. Silicon wafers were preamorphized with either 60 keV or 80 keV Ge+ at a dose of 1×1015 atoms/cm2. Subsequent 500 eV, 1×1015 atoms/cm211B+ implants, as well as 6 keV F+ implants with doses ranging from 1×1014 atoms/cm2 to 5×1015 atoms/cm2 were also done. Furnace anneals were conducted at 550°C for 10 minutes under an inert N2 ambient. Secondary Ion Mass Spectroscopy (SIMS) was utilized to characterize the occurrence of boron diffusion within amorphous silicon at room temperature, as well as during the Solid Phase Epitaxial Regrowth (SPER) process. Amorphous layer depths were verified through Cross-Sectional Transmission Electron Microscopy (XTEM) and Variable Angle Spectroscopic Ellipsometry (VASE). Boron motion within as-implanted samples is observed at fluorine concentrations greater than 1×1020 atoms/cm3. The magnitude of the boron motion scales with increasing fluorine dose and concentration. During the initial stages of SPER, boron was observed to diffuse irrespective of the co-implanted fluorine dose. Fluorine enhanced diffusion at room temperature does not appear to follow the same process as the enhanced diffusion observed during the regrowth process.
Advanced Thermal Processing of Semiconductor Materials by Flash Lamp Annealing
Authors: Skorupa W. , Panknin D. , Voelskow M. , Anwand W. ,   The European FLASiC Consortium, Gebel T. , Yankov R. A. , Paul Silke , Lerch Wilfried 
Published: April 2011

ABSTRACTThe use of flash lamp annealing for processing semiconductor materials is outlined. Specific applications include ultra-shallow junction formation and heteroepitaxial growth of improved quality thin films of cubic silicon carbide. It is demonstrated that flash lamp annealing holds great promise as a technique for fabricating novel devices.
The Effect of Oxide Trenches on Defect Formation and Evolution in Ion-Implanted Silicon
Authors: Burbure Nina , Jones Kevin S. 
Published: April 2011

ABSTRACTPattern induced defects during advanced CMOS processing can lead to lower quality devices with high leakage currents. Within this study, the effects of oxide trenches on implant related defect formation and evolution in silicon patterned wafers is examined. Oxide filled trenches approximately 4000Å deep were patterned into 300 mm <100> silicon wafers. Patterning was followed by ion implantation of Si+ at energies ranging from 10 to 80 keV. Samples were amorphized with doses of 1×1015 atoms/cm2, 5×1015 atoms/cm2, and 1×1016 atoms/cm2. Two independent repeating structures were studied. The first structure is comprised of silicon oxide filled trench lines, 3.7μm wide spaced 12.5μm apart, while the second structure contains silicon squares, 0.6μm on a side, surrounded by a silicon oxide filled trench. Cross- sectional and planar view transmission electron microscopy (TEM) samples were used to examine the defect morphology after annealing at temperatures ranging from 700°C to 950°C and at times between 1 second and 1 minute. Following complete regrowth, an array of defects was observed to form near the surface at the silicon/silicon oxide interface. These trench edge defects appeared to nucleate at the amorphous-crystalline interface for all energies and doses studied. Upon a spike anneal at 700°C, it was observed that regrowth of the amorphous layer had completed except in the region near the trench edge. Thus, it is believed that this defect results from the pinning of the amorphous-crystalline interface along the trench edge during solid phase epitaxial regrowth (SPER).
Influence of Atomic Hydrogen on Nickel Silicide Formation
Authors: Vengurlekar A. , Balasubramanian Satheesh , Ashok S. , Theodore N. D. , Chi D.Z. 
Published: April 2011

ABSTRACTNickel monosilicide (NiSi) is a leading contender to replace the currently used class of silicides for contacts to the source, drain and gate regions in Complimentary Metal-Oxide- Semiconductor (CMOS) circuits. In this work, the effect of substrate hydrogenation by a hydrogen plasma treatment prior to nickel deposition and silicidation was studied. The sheet resistance of the silicide film shows a significant decrease under hydrogenation of the Si substrate prior to Ni evaporation/anneal for projected silicidation temperatures below 600°C. Correspondingly, the Si region near the interface is decorated with defects. At higher silicidation temperatures, the sheet resistance rises along with greater in-diffusion of Ni into the hydrogenated Si samples. Secondary Ion Mass Spectrometry, Transmission Electron Microscopy and Hall effect measurements are used to characterize the samples.
Behavior of Si Interstitials and Boron-Interstitial Pairs at the Si/SiO2 Interface
Authors: Kirichenko Taras A. , Yu Decai , Banerjee Sanjay K. , Hwang Gyeong S. 
Published: April 2011

ABSTRACTUsing density functional theory calculations within the generalized gradient approximation, we have investigated the structure, energetics, bonding, and diffusion behavior of Si interstitials and boron-interstitial pairs at the Si/SiO2 interface. We find that interstitials are significantly stabilized at the Si/SiO2 interface and prefer to reside on the SiO2 side rather than the Si side. Due to the interstitial stabilization, boron-interstitial pairs are likely to be easily dissociated in the vicinity of the Si/SiO2 interface. This study provides valuable insight into interstitial annihilation and boron precipitation at the interface.
Role of C and Ge in the electrical activation of In implanted in Silicon
Authors: Scalese S. , Privitera V. , Italia M. , Magna A. La , Alippi P. , Renna L. 
Published: April 2011

ABSTRACTAn experimental study on In implantation in Si was performed, considering some factors that affect its electrical activation. One of the critical issues concerning In is represented by its outdiffusion, during the post-implantation annealing, a limiting factor to get active In concentration suitable for applications in microelectronics. The use of different thermal processes was evaluated, aimed to achieve a reduction of the outdiffusion and an increase of the electrical activation of In in silicon. The influence of the substrate purity on the electrical activation was shown to be of great importance: in particular, it was shown that C., present in the silicon substrate as a contaminant or as a co-implanted species, has a key-role in the electrical activation and diffusion of In in silicon. Furthermore, for the first time at our knowledge, the behaviour of In implanted in Si1−xGex layers grown by CVD on Si wafers was investigated, for Ge concentration of 0.5% and 1%. An enhancement in the electrical activation was observed with increasing the Ge content in the alloy.
The Effect of Environmental Chemistry on the Pb Assisted Stress Corrosion Cracking Susceptibility of Mill-Annealed Alloy 22 and GTAW Weldments
Authors: Csontos Aladar A. , Pan Yi-Ming , Dunn Darrell S. , Yang Leitai , Cragnolino Gustavo A. 
Published: April 2011

ABSTRACTThe susceptibility of mill-annealed (MA) and gas tungsten arc welded (GTAW) Alloy 22 to Pb-assisted stress corrosion cracking (PbSCC) was evaluated in supersaturated PbCl2 and Pb(NO3)2 solutions. The solution chemistries and pH were varied to evaluate the effects of specific Pb-bearing species on the SCC resistance of GTAW Alloy 22 double U-bend samples. Anodic polarization tests in acidic and basic supersaturated Pb(NO3)2 solutions indicated that the passive current densities generally increased with applied potential. These results were then compared to previous anodic polarizations results for supersaturated acidic PbCl2 solutions. Constant deformation SCC tests indicate that MA and GTAW Alloy 22 were resistant to PbSCC in supersaturated PbCl2 (16,000ppm Pb, 95°C, pH 0.5, and Eapplied = -100, -50, 0, and 50mVSCE) and Pb(NO3)2 (16,000ppm Pb, 95°C, pH 3.9 and 10.7 and Eapplied = 50 and 140mVSCE, respectively). The overall results from this PbSCC investigation suggest that MA and GTAW Alloy 22 are resistant to SCC in supersaturated PbCl2 and Pb(NO3)2 solutions at 95°C. Provided that these high Pb concentrations are not attainable in the anticipated repository environments, Alloy 22 is unlikely to be susceptible to SCC by the presence of Pb.
Process-Oriented Stress Modeling and Stress Evolution During Cu/Low-K BEOL Processing
Authors: Zhai Charlie Jun , Besser Paul R. , Feustel Frank 
Published: April 2011

AbstractThe damascene fabrication method and the introduction of low-K dielectrics present a host of reliability challenges to Cu interconnects and fundamentally change the mechanical stress state of Cu lines. In order to capture the effect of individual process steps on the stress evolution in the BEoL (Back End of Line), a process-oriented finite element modeling (FEM) approach was developed. In this model, the complete stress history at any step of BEoL can be simulated as a dual damascene Cu structure is fabricated. The inputs to the model include the temperature profile during each process step and materials constants. The modeling results are verified in two ways: through wafer-curvature measurement during multiple film deposition processes and with X-Ray diffraction to measure the mechanical stress state of the Cu interconnect lines fabricated using 0.13um CMOS technology. The Cu line stress evolution is simulated during the process of multi-step processing for a dual damascene Cu/low-K structure. It is shown that the in-plane stress of Cu lines is nearly independent of subsequent processes, while the out-of-plane stress increases considerably with the subsequent process steps.
Thermal Conductivity of Carbon Nanotube Composite Films
Authors: Ngo Quoc , Cruden Brett A. , Cassell Alan M. , Walker Megan D. , Ye Qi , Koehne Jessica E. , Meyyappan M. , Li Jun , Yang Cary Y. 
Published: April 2011

AbstractState-of-the-art ICs for microprocessors routinely dissipate power densities on the order of 50 W/cm2. This large power is due to the localized heating of ICs operating at high frequencies, and must be managed for future high-frequency microelectronic applications. Our approach involves finding new and efficient thermally conductive materials. Exploiting carbon nanotube (CNT) films and composites for their superior axial thermal conductance properties has the potential for such an application requiring efficient heat transfer. In this work, we present thermal contact resistance measurement results for CNT and CNT-Cu composite films. It is shown that Cu-filled CNT arrays enhance thermal conductance when compared to as-grown CNT arrays. Furthermore, the CNT-Cu composite material provides a mechanically robust alternative to current IC packaging technology.
Fundamental Limits for 3D Wafer-to-Wafer Alignment Accuracy
Authors: Wimplinger M. , Lu J.-Q. , Yu J. , Kwon Y. , Matthias T. , Cale T.S. , Gutmann R.J. 
Published: April 2011

AbstractWafer-level three-dimensional (3D) integration as an emerging architecture for future chips offers high interconnect performance by reducing delays of global interconnects and high functionality with heterogeneous integration of materials, devices, and signals. Various 3D technology platforms have been investigated, with different combinations of alternative alignment, bonding, thinning and inter-wafer interconnection technologies. Precise alignment on the wafer level is one of the key challenges affecting the performance of the 3D interconnects. After a brief overview of the wafer-level 3D technology platforms, this paper focuses on waferto-wafer alignment fundamentals. Various alignment methods are reviewed. A higher emphasis lies on the analysis of the alignment accuracy. In addition to the alignment accuracy achieved prior to bonding, the impacts of wafer bonding and subsequent wafer thinning will be discussed.