bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and elastic anisotropy of naturally deformed leucogneiss from a shear zone in Montalto (southern Calabria, Italy)
Authors: Cirrincione Rosolino , Fazio Eugenio , Heilbronner Renée , Kern Hartmut , Mengel Kurt , Ortolano Gaetano , Pezzino Antonino , Punturo Rosalda
Published: April 2010

A strain gradient was mesoscopically recognized in sheared leucogneisses cropping out near Mount Montalto (Calabria, southern Italy) in the Aspromonte–Peloritani Unit on the basis of field observations. In order to investigate the relationship between textural and physical anisotropy, a microstructural and petrophysical study was carried out on selected mylonites exhibiting different stages of deformation. The main mineral assemblage is Qtz+Pl+Kfs+Wm, displaying
S
–
C
and shear-band textures; mica-fish and ribbon-like quartz are widespread.

As strain increases K-feldspar, biotite and premylonitic low phengite white mica transformed to synmylonitic high phengite white mica and quartz, accompanied by an increasing albitization. Different quartz
c
-axis patterns are ascribable to non-coaxial progressive deformation; we suggest that deformation proceeded under greenschist- up to amphibolite-facies conditions owing to a local increase in shearing temperature.

Laboratory seismic measurements were carried out on sample cubes (43 mm edged) cut according to the structural frame (foliation, lineation) of the rock. At 400 MPa and room temperature the averages of compressional (
V
p
) and shear-wave velocities (
V
s
) are very similar: 5.70–5.91 and 3.36–3.55 km s
−1
, respectively. Seismic anisotropy and shear-wave splitting are related to the modal amounts of constituent minerals (in particular mica) and their crystallographic preferred orientation. Importantly, anisotropy is lowest in the most strained rock.
Geometry of intercrystalline brine in plastically deforming halite rocks: inference from electrical resistivity
Authors: Watanabe Tohru
Published: April 2010

Electrical impedance measurements were performed on deforming fine-grained (
c.
300 µm) synthetic halite rocks containing small quantities of water in order to study the distribution of intercrystalline brine. The experimental conditions were 125 °C and 50 MPa confining pressure. The resistivity at the predeformational, heated and hydrostatically pressurized state suggests that brine is interconnected in halite. The resistivity progressively increases with deformation, reflecting the change in distribution. In this paper we applied a simple tube model to the resistivity change, and found that the change must be caused by deformation of a thin fluid path with an initial aspect ratio of less than 2×10
−4
. Brine must, therefore, exist on grain boundaries as a thin fluid film. Previous studies on dihedral angles, however, showed that brine cannot be interconnected under our experimental conditions. The variation in grain-boundary energy cannot explain the coexistence of grain-boundary brine with a positive dihedral angle. The observed resistivity change requires grain-boundary brine to be very thin (<100 nm). Such a thin fluid film might have properties distinct from the bulk fluid, and coexist with brine pores at grain corners and grain faces.
Block model versus thermomechanical model: new insights on the present-day regional deformation in the surroundings of the Calabrian Arc
Authors: Splendore Raffaele , Marotta Anna Maria , Barzaghi Riccardo , Borghi Alessandra , Cannizzaro Letizia
Published: April 2010

A finite-element thermomechanical model is used to analyse present-day crustal deformation in the surroundings of the Calabrian Arc. The major structural complexities of the Tyrrhenian area are taken into account, along with the rheological properties of the rocks resulting from a thermal analysis. A comparison between the results obtained from a model composed of three wide rheologically uniform blocks and those obtained from the thermomechanical model allows us to better constrain the geophysical assumptions and shed light on the roles of the different active mechanisms acting in the Tyrrhenian. Our comparative analysis enlightens the crucial role played by lateral rheological heterogeneities when deformation is analysed at short wavelengths of a few hundred kilometres of the Tyrrhenian, driving the observed diffuse SW–NE extension within the regional context of active Africa–Eurasia convergence. Furthermore, a χ
2
analysis based on comparisons with GPS data confirms the hypothesis that a significant part of the Africa–Eurasia convergence is absorbed through the Calabrian subduction.
Analysis and approximation for bank selection instruction minimization on partitioned memory architecture
Authors: Li Minming , Xue Chun Jason , Liu Tiantian , Zhao Yingchao
Published: April 2010

A large number of embedded systems include 8-bit microcontrollers for their energy efficiency and low cost. Multi-bank memory architecture is commonly applied in 8-bit microcontrollers to increase the size of memory without extending address buses. To switch among different memory banks, a special instruction, Bank Selection, is used. How to minimize the number of bank selection instructions inserted is important to reduce code size for embedded systems.

In this paper, we consider how to insert the minimum number of bank selection instructions in a program to achieve feasibility. A program can be represented by a control flow graph (CFG). We prove that it is NP-Hard to insert the minimum number of bank selection instructions if all the variables are pre-assigned to memory banks. Therefore, we introduce a 2-approximation algorithm using a rounding method. When the CFG is a tree or the out-degree of each node in the CFG is at most two, we show that we can insert the bank selection instructions optimally in polynomial time. We then consider the case when there are some nodes that do not access any memory bank and design a dynamic programming method to compute the optimal insertion strategy when the CFG is a tree. Experimental result shows the proposed techniques can reduce bank selection instructions significantly on partitioned memory architecture.
Look into details
Authors: Foroozannejad Mohammad H. , Hashemi Matin , Hodges Trevor L. , Ghiasi Soheil
Published: April 2010

Many embedded applications demand processing of a seemingly endless stream of input data in real-time. Productive development of such applications is typically carried out by synthesizing software from high-level specifications, such as data-flow graphs. In this context, we study the problem of inter-actor buffer allocation, which is a critical step during compilation of streaming applications. We argue that fine-grain analysis of buffers' spatio-temporal characteristics, as opposed to conventional live range analysis, enables dramatic improvements in buffer sharing. Improved sharing translates to reduction of the compiled binary memory footprint, which is of prime concern in many embedded systems. We transform the buffer allocation problem to two-dimensional packing using complex polygons. We develop an evolutionary packing algorithm, which readily yields buffer allocations. Experimental results show an average of over 7X and 2X improvement in total buffer size, compared to baseline and conventional live range analysis schemes, respectively.
Translating concurrent action oriented specifications to synchronous guarded actions
Authors: Brandt Jens , Schneider Klaus , Shukla Sandeep K.
Published: April 2010

Concurrent Action-Oriented Specifications (CAOS) model the be- havior of a synchronous hardware circuit as asynchronous guarded actions at an abstraction level higher than the Register Transfer Level (RTL). Previous approaches always considered the compilation of CAOS, which includes a transformation of the under-lying model of computation and the scheduling of guarded actions per clock cycle, as a tightly integrated step. In this paper, we present a new compilation procedure, which separates these two tasks and translates CAOS models to synchronous guarded actions with an explicit interface to a scheduler. This separation of con- cerns has many advantages, including better analyses and integration of custom schedulers. Our method also generates assertions that each scheduler must obey that can be fulfilled by algorithms for scheduler synthesis like those developed in supervisory control. We present our translation procedure in detail and illustrate it by various examples. We also show that our method simplifies for- mal verification of hardware synthesized from CAOS specifications over previously known formal verification approaches.
Integrating safety analysis into the model-based development toolchain of automotive embedded systems
Authors: Biehl Matthias , DeJiu Chen , Törngren Martin
Published: April 2010

The automotive industry has a growing demand for the seamless integration of safety analysis tools into the model-based development toolchain for embedded systems. This requires translating concepts of the automotive domain to the safety domain. We automate such a translation between the automotive architecture description language EAST-ADL2 and the safety analysis tool HiP-HOPS by using model transformations and by leveraging the advantages of different model transformation techniques. Through this integration, the analysis can be conducted early in the development process, when the system can be redesigned to fulfill safety goals with relatively low effort and cost.
Cache vulnerability equations for protecting data in embedded processor caches from soft errors
Authors: Shrivastava Aviral , Lee Jongeun , Jeyapaul Reiley
Published: April 2010

Continuous technology scaling has brought us to a point, where transistors have become extremely susceptible to cosmic radiation strikes, or soft errors. Inside the processor, caches are most vulnerable to soft errors, and techniques at various levels of design abstraction, e.g., fabrication, gate design, circuit design, and microarchitecture-level, have been developed to protect data in caches. However, no work has been done to investigate the effect of code transformations on the vulnerability of data in caches. Data is vulnerable to soft errors in the cache only if it will be read by the processor, and not if it will be overwritten. Since code transformations can change the read-write pattern of program variables, they significantly effect the soft error vulnerability of program variables in the cache. We observe that often opportunity exists to significantly reduce the soft error vulnerability of cache data by trading-off a little performance. However, even if one wanted to exploit this trade-off, it is difficult, since there are no efficient techniques to estimate vulnerability of data in caches. To this end, this paper develops efficient static analysis method to estimate program vulnerability in caches, which enables the compiler to exploit the performance-vulnerability trade-offs in applications. Finally, as compared to simulation based estimation, static analysis techniques provide the insights into vulnerability calculations that provide some simple schemes to reduce program vulnerability.
Resilience analysis
Authors: Altmeyer Sebastian , Maiza Claire , Reineke Jan
Published: April 2010

In preemptive real-time systems, scheduling analyses need - in addition to the worst-case execution time - the context-switch cost. In case of preemption, the preempted and the preempting task may interfere on the cache memory.

This interference leads to additional cache misses in the preempted task. The delay due to these cache misses is referred to as the cache-related preemption delay~(CRPD), which constitutes the major part of the context-switch cost.

In this paper, we present a new approach to compute tight bounds on the CRPD for LRU set-associative caches, based on analyses of both the preempted and the preempting task. Previous approaches analyzing both the preempted and the preempting task were either imprecise or unsound.

As the basis of our approach we introduce the notion of resilience: The resilience of a memory block of the preempted task is the maximal number of memory accesses a preempting task could perform without causing an additional miss to this block. By computing lower bounds on the resilience of blocks and an upper bound on the number of accesses by a preempting task, one can guarantee that some blocks may not contribute to the CRPD. The CRPD analysis based on resilience considerably outperforms previous approaches.
Excitation Mechanisms of Green Emission from Terbium Ions Embedded Inside the Sol-Gel Films Deposited onto Nanoporous Substrates
Authors: Podhorodecki Artur , Gaponenko Nikolai , Bański Mateusz , Kim T. , Misiewicz Jan
Published: April 2010

In this work we investigate the excitation mechanism of Tb3+ ions in different inorganic sol-gel matrices (composite film of YAlO3 and Al2O3; Ba0,6Sr0,3Ca0,1:TiO3) in porous anodic alumina films. The interest in synthesis of light-emitting materials in porous anodic alumina arises from its unique tailor-made honey-comb structure, strongly enhanced Tb luminescence and great photonic density of states at direction along the channels of the anisotropic light scattering. All discussed sol-gel films were synthesized by spin-on deposition on porous anodic alumina grown on a silicon wafer and annealed at different temperatures. An influence of the annealing temperature on the terbium PL was studied using XRD, 2D photoluminescence excitation and time-resolved spectroscopy. Further, the comparison of thermal quenching data for the most intensive 5D4 →7F5 luminescence band and excitation band of Tb 3+ ions was performed for the temperature range of 10 - 300 K. From the resultant data, mechanisms of Tb excitation and its dependence on the annealing conditions are proposed and discussed.
(Invited) Electropolymerized Poly(para-phenylene)vinylene Films onto and Inside Porous Si
Authors: Gelloz Bernard , Mentek Romain , Djenizian Thierry , Dumur F. , Jin Lianhua , Koshida Nobuyoshi
Published: April 2010

The electrochemical deposition of poly(para-phenylene)vinylene (PPV) into the pores of porous silicon (PSi) has been investigated using acetonitrile as solvent and p-xylylene-α,α'-bis(triphenylphosphonium chloride as precursor. PPV was successfully deposited onto various Si substrates and PSi layers. It was also deposited inside p+-type and p-type PSi. The as-deposited PPV is strongly luminescent. The deposition was confirmed by optical (photoluminescence, reflectivity) and structural analysis (FTIR, SEM). The deposited PPV was smooth without peeling on PSi layers. With strongly luminescent n+-type PSi, the rate of the deposition was limited by the large resistivity of PSi. The deposition was found dramatically affected by the PSi nanostructure through the diffusion of precursors in the pores and charge carrier transport in PSi.
Synthesis and Photoluminescence Characteristics of Sr3Y1-x(PO4)3:xTb3+Nanoparticles
Authors: Taxak Vinod B. , Han Sang-Do , Kumar Mukesh , Khatkar Satyender P.
Published: April 2010

In the present work, Tb3+ doped Sr3Y1-x(PO4)3:xTb3+ nanocrystals were synthesized by combustion method using urea as a fuel. Comparing with traditional material processing techniques, combustion method is a relatively simple method. The advantages of low temperature solution base process have been exploited to produce Sr3Y1-x(PO4)3:xTb3+ nanoparticles. The nano crystals obtained through combustion method was characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD) technique and photoluminescence (PL) spectra. The predominant green colour of the nanocrystals prepared, under an UV source revealed green luminescence that was attributed to transitions 5D4 → 7F5 of Tb3+ located at 545 nm. The particle size of the nanocrystals was found to be in the range of 35nm.
Co-Doping Effects of Zn2+ on Upconversion Luminescence of Gd2O3:Er Nanophosphors
Authors: Xu Lingling , Shen Yanqiu , Liu Juan , Zhai Di , Zhang Zhiguo
Published: April 2010

Zn2+ and Er3+ ions co-doped Gd2O3 nanophosphors were synthesized via a citric acid complexing method. The crystalline characterization shows that the Zn2+ doping induced a shrinking effect of the host cell by changing the lattice constant. Both Stokes photoluminescence and upconversion emission were significantly enhanced by the Zn2+ doping. The reason for emission enhancement was mainly ascribed to the lowered crystal symmetry of lattice by introducing oxygen vacancy.
New Electrochromic Systems for the Color E-Paper
Authors: Noh Chang Ho , Jeon Seog Jin , Das Rupasree R. , Chung Deuk Seok , Jin Yong Wan , Son Seung Uk
Published: April 2010

Here we describe the newly designed electrochromic(EC) materials to improve the three primary colors (RGB) and bistability. We also report the printed color image of EC device which shows good reversibility and memory. The use of a reflector furnishes good white reflectance of a value of above 50%. The simple structure and easy driving method allow the device application in various areas, such as simple segment driving devices, display information board, and paper like displays (PLD).
Tartaric Acid Assisted Sol-Gel Synthesis and Photoluminescence Characteristics of SrY2(1-x)O4 : xTb Nanoparticles
Authors: Taxak Vinod B. , Khatkar Satyender P. , Kumar Mukesh , Han Sang-Do
Published: April 2010

A novel green light emitting nano-sized phosphor, Tb3+ doped SrY2(1-x)O4 was synthesized using tartaric acid assisted sol-gel process. Comparing with traditional material processing techniques, sol-gel process is a relatively simple method. The advantages of low temperature solution base process have been exploited to produce SrY2(1-x)O4: xTb nano particles and the phase transformation involved in the pure homogeneous mixture formation. The nano crystals obtained through sol-gel method was characterized by XRD, photoluminescence (PL) spectra and scanning electron microscopy (SEM). The nanocrystals prepared under an UV source revealed green luminescence that was attributed to transition 5D4 → 7F5 of Tb3+ was located at 543 nm. The particle size of the nanocrystals was found to be in the range of 40-50nm.
Identification of Two Luminescence Sites of Sr2SiO4:Eu2+ and (Sr,Ba)2SiO4:Eu2+ Phosphors
Authors: Nguyen Hoang-Duy , Yeo In-Hyeong , Mho Sun-il
Published: April 2010

Europium activated strontium orthosilicate Sr2SiO4:Eu2+ phosphors were prepared by a solid state reaction method using flux. Two emissions bands of blueish-green at 490 nm (SI) and of yellow at 560 nm (SII) were observed. The two emission bands are assigned to the 4f-5d transition of Eu2+ ions in two different cation sites in α'-Sr2SiO4 orthorhombic lattices. The relative intensities of two emission bands and the efficient yellow-emission strongly depend on the fluxes used for the preparation process and the Eu2+ concentration in the Sr2SiO4:Eu2+ phosphors. The emission intensity of Eu2+ was also increased especially for the SII site, by incorporating Ba2+ into the lattice (BaxSr2-xSiO4).
Preparation of (Y,Gd)3Al5-2y(Si,Mg)yO12:Ce Phosphor by Spray Pyrolysis: Effect of Precursor Type and Flux on Its Luminescence Characteristics
Authors: Maniquiz Meriel , Jung Kyeong Youl
Published: April 2010

A series of Si4+-Mg2+ couple substituted in the Al site of the host lattice, (Y,Gd)3Al5-2y(Mg,Si)yO12:Ce3+ (y=0~2) were prepared by spray pyrolysis and their photoluminescence characteristics and thermal stabilities were studied. B(OH)3 flux was used to improve the emission intensity of the (Y,Gd)3Al(Mg,Si)2O12:Ce3+ phosphor. As increasing the Si-Mg content (up to y=2), the emission wavelength was gradually shifted from 550 nm to 582 nm, accompanying with a significant decrease in the emission intensity. In terms of emission intensity and thermal quenching, Si3N4 nanopowder was better than tetra-ethyl orthosilicate (TEOS) as a Si precursor. The use of B(OH)3 as a flux was effective to enhance the emission intensity which could be improved almost 170% compared with phosphors synthesized without fluxes.
(Invited) High Performance Quantum Dot Microtube Lasers and Nanowire LEDs on Si
Authors: Mi Zetian , Chang Yi-Lu , Li Feng , Wang Jiale
Published: April 2010

We report on the recent achievements of rolled-up InGaAs/GaAs quantum dot microtube lasers as well as high efficiency InGaN/GaN dot-in-a-wire nanoscale heterostructures on Si. Free-standing rolled-up microtube ring resonators are formed by controlled release of coherently strained InGaAs/GaAs quantum dot heterostructures from the host substrate. We have demonstrated optically pumped rolled-up microtube lasers, which exhibit emission wavelengths in the range of 1.1 - 1.3 μm and a low threshold of ~ 4 μW at room temperature. For applications in solid state lighting, we have further developed nearly defect-free, vertically aligned InGaN/GaN dot-in-a-wire nanoscale heterostructures on Si(111) substrates. Strong green, yellow, and amber emission, with an internal quantum efficiency of ~ 45% was achieved.
Interaction of Hydroxamates with Malachite
Authors: Hope Gregory A. , Woods Ronald , Parker Gretel K.
Published: April 2010

The interaction of alkyl hydroxamate in 0.1 M KOH with a malachite or azurite mineral surface has been investigated using Raman spectroscopy. Cupric hydroxamate was detected on the mineral surface following exposure in aerated solutions. Gold film coating or colloid deposition was not successful in the enhancement of spectra from the exposed mineral surfaces. Surface enhanced Raman scattering was obtained from roughened gold electrodes or gold colloid particles exposed to aerated hydroxamates. These spectra exhibit potential dependent formation of a species with a carbon nitrogen triple bond, indicative of oxidative decomposition of the hydroxamate functional group.
ARXPS and SXPS Evidence for Surface Stabilization of Sphalerite Zn1-xFexS (110) Surfaces
Authors: Harmer Sarah L. , Nesbitt H. W. , Skinner William M. , Buckley Alan N. , Pratt Allen
Published: April 2010

Angle resolved X-ray photoelectron spectroscopy (ARXPS) and synchrotron XPS (SXPS) have been used to study the (110) surface of two Fe containing sphalerites cleaved in vacuo. The ARXPS S 2p and Zn 2p spectra collected from a low Fe (0.02 wt.%) sphalerite revealed a low binding energy peak when collected at low take off angles (20°). These peaks have been assigned as surface core-level shifts of ~ -0.46 eV and ~ +0.34 eV, respectively. The ARXPS and SXPS S 2p spectra collected from a high Fe (14.79 wt.%) sphalerite indicated the presence of a low binding energy peak resulting from a core level shift ~ -0.42 eV below the bulk S 2p line. A higher binding energy contribution, attributed to a second surface species, was found +0.47 eV above the bulk S 2p doublet. Comparison of the S 2p spectra collected from the two sphalerites, suggested that high Fe concentrations might induce surface reconstruction in the form of surface S dimers. The surface S dimers are likely to be concentrated at high energy step edges and defects.
Production of Oxidizing Intermediates during Corrosion of Iron: Implications for Remediation of Contaminants from Mineral and Metal Processing
Authors: Pham Anh L. , Sedlak David L. , Doyle Fiona M.
Published: April 2010

Elemental iron has a long history of use for reductive recovery of dissolved metals from waters associated with ore bodies, mining and mineral processing activities. It has recently been recognized that Fenton's reagent, which generates powerful oxidants, may be generated when iron corrodes in the presence of oxygen. If the iron is nanoparticulate, enough oxidant may be generated for practical applications. However, there is ample indication in the literature that oxidation reactions on iron at near-neutral pH are strongly sensitive to the source of the iron, which affects the surface. This was investigated here for electrolytic iron powder, and two types of nanoparticulate iron, using a modified packed powder electrode. The behavior of bulk iron was investigated using a rotating disk electrode. The results revealed significant differences in the corrosion behavior of the different iron samples, indicating that these would yield significantly different results if employed for oxidation reactions.
The Pyrite Catalysed Oxidation of Sulfide Ions
Authors: Hewitt Danielle M. , Breuer Paul L. , Jeffrey Matthew I.
Published: April 2010

The oxidation of sulfide ions in cyanide solutions by oxygen is catalysed by pyrite. Polysulfides are detected as an intermediate product in the oxidation reaction for both cyanide and non-cyanide alkaline solutions. The major product for oxidation in the absence of cyanide is thiosulfate, whilst thiocyanate is dominant for the cyanide containing system. Electrochemical studies of sulfide oxidation are consistent with the formation of polysulfides being the initial oxidation step for both the cyanide and non-cyanide systems. However, the reduction of oxygen is significantly slower on pyrite in the presence of cyanide, leading to reduced rates of oxidation of sulfide by oxygen. Another important observation was that some pyrite oxidation by oxygen occurred concurrently with sulfide oxidation, despite the mixed potential being in the region where pyrite oxidation is very slow in the absence of sulfide.
Attributes of Electrochemical Potential in a Multi-Physics Heap Leach Model
Authors: Gebhardt James E. , Bennett Christopher R. , McBride Diane , Cross Mark
Published: April 2010

A multi-physics software framework has been used to develop a comprehensive heap leach model that allows the user to simulate reactive dissolution and flow through the stockpile. Based on the fundamental physics and chemistry, including reaction kinetics, mass and energy balances provide predictions of soluble species concentrations in the pregnant leach solution (i.e., heap discharge) and at locations throughout the heap and estimated temperatures within the heap. A description of the kinetic models employed for dissolution of the sulfide mineral species is provided for various copper minerals, including the estimation of electrochemical potential. Aspects of the electrochemical potential in a multi-physics based model, and its effect on process chemistry and on heap optimization, are discussed.
An Approach to the Reactivity of Isomorphous Proustite (Ag3AsS3) and Pyrargyrite (Ag3SbS3) in Cyanide Solutions
Authors: Meléndez Angel M. , González Ignacio , Arroyo Rubén
Published: April 2010

The electrochemical reactivity of the sulfosalts pyrargyrite and proustite in cyanide media was studied with two different types of electrodes: an electroactive carbon paste electrode (CPE) and a paraffin impregnated graphite electrode (PIGE). To avoid impurities present in natural specimens, polycrystalline samples (acanthite, stibnite, pyrargyrite and proustite) were synthesized by a solid-state reaction method. Phase identification was carried out by XRD and chemical homogeneity was checked by SEM-EDX. In addition, samples were characterized by diffuse reflectance spectroscopy. Reactivity is similar for the isostructural phases pyragyrite and proustite. However, SbIII in pyrargyrite is oxidized at less positive potentials than AsIII in proustite. Oxidation of SbIII to SbV occurs in a similar range of potentials in both Sb2S3 and Ag3SbS3, because the substructure SbS3 in stibnite and pyrargyrite have similar chemical characteristics.
A Spectroelectrochemical Investigation of the Interaction of Gold with Cyano-Containing Ligands
Authors: Parker Gretel K. , Hope Gregory A.
Published: April 2010

Surface-enhanced Raman spectroelectrochemical (SERS) investigations of cyanamide, cyanoacetamide and malononitrile interaction with a roughened gold electrode were undertaken. The reagents were readily adsorbed on the surface and large shifts in the C≡N stretch band were observed on adsorption. The C≡N frequency underwent Stark tuning as the potential was scanned and, at high potentials, bands consistent with an oxidized gold complex were observed. It did not appear that the cyano functional group dissociated from the ligands and, together with the large shift in the C≡N stretch frequency on adsorption, this is indicative of π-type coordination. The 1st and subsequent voltammetric cycles in the malononitrile system showed quite different characteristics, indicative of bonding of only one of the two nitriles of the molecule to the gold surface during the 1st oxidation sweep, followed by bonding of both the nitriles in subsequent sweeps.
An Electrochemical Study of the Dissolution of Pure Gold and Gold-Silver Alloys in Thiosulfate Leach Solutions
Authors: Oraby El-Sayed A. , Jeffrey Matthew I.
Published: April 2010

A fundamental electrochemical study of gold and gold/silver alloys in thiosulfate solutions showed that although the oxidation is a complex process, there was no selective dissolution of either gold or silver from the alloys during oxidation. The presence of copper and thiourea catalyses the oxidation of the alloys, resulting in good leaching for thiosulfate systems when utilising either of these species. Surprisingly for copper containing solutions, the oxidation rate is largely independent of potential, and is higher for pure gold than for the 4% Ag and 8% Ag alloys. For thiourea containing solutions, the rate of alloy oxidation increases with increases in the silver content of the alloy. In the absence of copper of thiourea, the only alloy which showed appreciable oxidation was 50% Au / 50% Ag, although the rate of oxidation did increase with an increase in silver content from 0 to 50%.
Investigating Gold Dissolution during Oxidative Desorption of Alkylthiol Self-Assembled Monolayers
Authors: Smith Scott R. , Guerra Eduard , Shepherd Jeffrey L.
Published: April 2010

The properties of alkylthiol self-assembled monolayers (SAMs) on Au have been extensively characterized in the past few decades by exploiting a one-electron reductive desorption process. To date, oxidative desorption of thiol SAMs has been relatively understudied because the Au surface can be roughened during the oxidative desorption event. In this paper we describe the oxidative desorption of alkylthiols with cyclic voltammetry and report the effect of pH, thiol functional group and chloride concentration on the peak potential for desorption. These peak potentials are compared with the visible observation of Au surface roughening and the oxidative dissolution of Au, which will be verified with atomic absorption spectroscopy. The implications of these results in terms of finding a replacement for cyanide in industrial gold leaching are discussed.
An Investigation on the Effects of Organic Additives on Zinc Electrowinning from Industrial Electrolyte
Authors: Dhak Debasis , Asselin Edouard , Di Carlo S. , Alfantazi Akram
Published: April 2010

The influence of Saponin, Licorice, Tennafroth 250, and Dowfroth 250 at different concentration levels (0, 5, 10, and 15 ppm) were investigated during zinc electrowinning from industrially supplied spent electrolyte. Acid mist suppression efficiency, polarization behavior, current efficiency and energy consumption were investigated for a current density of 500 A.m-2. Surface tension measurements were used to find a correlation between the concentration of the different additives and the acid mist suppression efficiencies. Morphological and crystallographic orientation studies indicated dense and well defined crystalline grains with homogeneous distribution mostly at the 5 ppm level of suppressant. The electrowinning in presence of Saponin and Tennafroth were found to have high current efficiencies of 90% each with low energy consumptions of 2641 and 2675 kWh/t, respectively and the deposited crystals were found to be oriented preferably in the [101], [102], [103] and [112] planes for both.
Electrowinning of Copper from Copper Cyanide Solutions at Low pH
Authors: Dai Xianwen , Breuer Paul L. , Jeffrey Matthew I.
Published: April 2010

The electrodeposition of copper from solutions containing free cyanide is difficult under alkaline conditions, but can be substantially enhanced by decreasing the pH due to the formation of the more electroactive aqueous species, Cu(CN)2-. The optimum pH for electrowinning is pH 5, and the electrodeposition of copper is significantly enhanced in an acetate solution due to the minimization of interfacial pH change. Cu(CN)2- was found to be readily oxidized at potentials more positive than 550 mV, and an anode material has yet to be found that promoted oxygen evolution over the oxidation of copper cyanide. At pH 5, the current efficiency increases as the cathode potential shifts to more positive potentials, whilst the copper recovery rate decreases as the potential becomes more positive than -600 mV. The optimum operating cathode potential is between 500 and 600 mV, giving a current efficiency of 90 - 100 % and an average energy consumption of 0.85 - 1.00 kWh/kgCu.
Electrowinning of Iron from Alkaline Solution
Authors: Tang Shuihua H. , Haarberg Geir M.
Published: April 2010

Electrowinning of iron from alkaline solution containing ferric oxide, silica, and alumina was investigated by constant current electrolysis at 110°C. The deposits were analyzed by scanning electron microscope (SEM) coupled with an energy dispersive X-ray spectrometer (EDS). The SEM images demonstrated that there were small gaps between columns, which stacked up with six twin crystals when the electrolyte silica and alumina content was up to 20 wt%, but EDS results showed that the purity was still high. This indicated that electrowinning of iron should be possible directly from iron ore without further purification.
Anodic Formation of Cobalt Oxide during Electrowinning of Cobalt in a Chloride Electrolyte
Authors: Kongstein Ole E. , Haarberg Geir M. , Thonstad Jomar
Published: April 2010

During electrowinning of cobalt, in addition to anodic chlorine and oxygen evolution, deposition of a black substance was observed on the DSA anode. The black substance was investigated by means of XRD, and found to be trivalent cobalt oxy-hydroxide (alpha−CoOOH). The deposition of cobalt oxy-hydroxide and possible ways to prevent this deposition were studied. Experiments showed that deposited cobalt oxy-hydroxide could be dissolved cathodically. The amount of charge for cathodic dissolution was used to estimate the deposited amount of cobalt oxy-hydroxide. In agreement with thermodynamics, the deposition of cobalt oxy-hydroxide decreased with decreasing pH. The results also showed that deposition of CoOOH could be suppressed by addition of H2O2.
Electrochemical Deposition of Nanoparticulate Materials
Authors: Hope Gregory A. , Liu Peng , Li Haohua , Parker Gretel K.
Published: April 2010

The reaction of selenous acid with template grown indium nanowires generates a poorly structured indium (I) selenide tubular product. The electron diffraction pattern from the sample exhibited no crystallinity. The Raman spectrum of the deposit is a broad band centred on 160 cm-1 that is not consistent with the known Raman spectra for indium selenides or elemental selenium. Annealing of the deposit yielded a polycrystalline tube structure where the tubes are similar in size to the as-deposited material. SAED of the grains that form these tubes revealed them to be individual indium (I) selenide crystals.
Electronic Transport Properties of Graphene pn Junctions and Its Electron Optics
Authors: Low Tony , Lundstrom Mark S.
Published: April 2010

The electronic transport properties of graphene pn junctions are examined using the non-equilibrium green's function (NEGF) simulation approach. We then review the basic physics involved in the conductance modulation of a graphene pn junction. The understanding derived from these studies sets the stage for exploring the potential applications of Klein tunneling, negative refractive index, and total internal reflection for realization of novel electron optics devices and spatial manipulation of current flow.
Ultra-High Vacuum Processing and Characterization of Chemically Functionalized Graphene
Authors: Wang Qing Hua , Hersam Mark C.
Published: April 2010

The chemical functionalization of graphene in ultra-high vacuum (UHV) with monolayers of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) has been characterized with scanning tunneling microscopy (STM). The molecules self-assemble into stable, well-ordered monolayers that are arranged in a herringbone phase with extended domains spanning hundreds of nanometers. At submonolayer coverage, PTCDA forms stable, isolated molecular islands. The molecular ordering is unperturbed by either defects in the epitaxial graphene or atomic steps in the underlying SiC surface. Scanning tunneling spectroscopy (STS) performed on the PTCDA monolayers reveals strong features in the electronic density of states that are distinct from the pristine graphene regions. The demonstration of robust, uniform organic functionalization of epitaxial graphene is an important step toward realizing graphene-based molecular electronic and sensing devices.
Growth Kinetics and Defects of CVD Graphene on Cu
Authors: Colombo Luigi , Li Xuesong , Han Boyang , Magnuson Carl , Cai Weiwei , Zhu Yanwu , Ruoff Rodney S.
Published: April 2010

Growth of high quality graphene is the basis for the successful demonstration and reduction to practice of electronic devices and transparent conductive electrodes. To date the highest quality devices have been fabricated on graphene exfoliated from natural graphite or Kish graphite, unfortunately this source of graphene is not scalable to sizes required by manufacturing processes. We used chemical vapor deposition (CVD) to grow monolayer graphite or graphene on large area Cu substrates. This technique by its nature is scalable to sizes that are compatible to almost any size requirement. We report on the improvement of the physical properties of graphene on Cu through basic understanding of the growth kinetics. We found that defects associated with the Raman D-band can be reduced by changing the growth process conditions and the sheet resistance is reduced as the D-band defects are reduced.
High Mobility SiGe Channel NonPlanar Devices
Authors: Hobbs Christopher , Smith Casey , Adhikari Hemant , Lin ShengHao , Ok Injo , Akarvardar Kerem , Lee Se-Hoon , Coss Brian , Young Chadwin , Cruz Melvin , Majhi Prashant , Jammy Raj
Published: April 2010

We report on the promise of using SiGe channel FinFETs for high performance CMOS for the sub-22nm node. Devices with Si, stacked SiGe/Si, shell/core SiGe/Si and homogeneous SiGe fins with (110) and (100) surface orientations were fabricated and characterized. The stacked SiGe/Si fin device exhibited a dual turn-on due to the SiGe and Si regions. The shell/core SiGe/Si fin device mobility was 30% greater than the Si fin. The homogeneous SiGe fin device with a (110) orientation had a mobility 3.6X higher than the Si fin device with a (100) orientation.
(Invited) Exploring the ALD Al2O3/In0.53Ga0.47As and Al2O3/Ge Interface Properties: A Common Gate Stack Approach for Advanced III-V/Ge CMOS
Authors: Lin Dennis , Waldron Niamh , Brammertz Guy , Martens Koen , Wang Wei-E , Sioncke Sonja , Delabie Annelies , Bender Hugo , Conard Thierry , Tseng W. H. , Lin J.C. , Temst Kristiaan , Vantomme Andre , Mitard Jerome , Caymax Matty , Meuris Marc , Heyns Marc , Hoffman Thomas
Published: April 2010

A new passivation approach integrating the III-V/Ge MOSFET gate stack processes for a complete CMOS solution is proposed. We explore the In0.53Ga0.47As and Ge MOS electrical properties and present the common gate stack (CGS) concept based on the complementary nature of the asymmetric oxide-In0.53Ga0.47As and the oxide-Ge interface state distributions. In addition, this approach requires neither the interfacial passivation layer (IPL) such as Si, nor the native oxide such as the GeO2, between the gate dielectric and the channels. The oxide-semiconductor interface properties of the common gate stack III-V/Ge MOS system have been carefully investigated and MOS transistors have been fabricated to validate the proposed common gate stack concept. It has been demonstrated that the above common gate stack MOS system can achieve high-performance n-channel operation on In0.53Ga0.47As substrates and p-channel operation on Ge substrates.
Scaling of InGaAs MOSFETs into Deep-Submicron
Authors: Wu Yanqing , Ye Peide
Published: April 2010

We have demonstrated high-performance deep-submicron inversion-mode InGaAs MOSFETs with gate lengths down to 150 nm with record Gm exceeding 1.1 mS/µm. Oxide thickness scaling is performed to improve the on-state/off-state performance and Gm is further improved to 1.3 mS/µm. HBr pre-cleaning, retro-grade structure and halo-implantation processes are first time introduced into III-V MOSFETs to steadily improve high-k/InGaAs interface quality and on-state/off-state performance of the devices. We have also demonstrated the first well-behaved inversion-mode InGaAs FinFET with ALD Al2O3 as gate dielectric using novel damage-free etching techniques. Detailed analysis of SS, DIBL and VT roll-off are carried out on FinFETs with Lch down to 100 nm and WFin down to 40 nm. The short-channel effect (SCE) of planar InGaAs MOSFETs is greatly improved by the 3D structure design. The result confirms that the newly developed dry/wet etching process produces damage-free InGaAs sidewalls and the high-k/3D InGaAs interface is comparable to the 2D case.
(Invited) Scaling FETs to 10 nm: Coulomb Effects, Source Starvation, and Virtual Source
Authors: Fischetti Massimo V. , Jin Seonghoon , Tang Ting-wei , Asbeck Peter , Taur Yuan , Laux Steven , Sano Nobuyuki , Rodwell Mark
Published: April 2010

In our attempts to scale FETs to the 10 nm length, alternatives to conventional Si CMOS are sought on the grounds that: 1. Si seems to have reached its technological and performance limits and 2. The use of alternative high-mobility channel materials will provide the missing performance. With the help of numerical simulations here we establish the reasons why indeed Si seems to have hit a performance barrier and whether high-mobility semiconductors can indeed grant us our wishes. We discuss the effect of long- and short-range electron-electron interactions in connection with a recent analysis of the historical performance trends. The density-of-states (DOS) bottleneck and source starvation issues is also reviewed to see what advantage alternative substrates may bring us. Finally, the well-known 'virtual source model' is analyzed to assess whether it can be used as a quantitative tool to guide us to the 10 nm gate length.
Carrier Mobility Variations in Self-Aligned Germanium MOS Transistors
Authors: Low YeeHooi , Tantraviwat Doldet , Rainey Paul , Baine Paul , McNeill David W. , Mitchell Neil S. , Armstrong Brian M. , Gamble Harold
Published: April 2010

Tungsten gate germanium MOS transistors have been manufactured on bulk germanium platforms. Hole mobility in the range 450 cm2/Vs has been achieved on bulk germanium, but mobility is reduced during the densification of thinner dielectrics at 600C. This may be due to the formation of volatile GeO at the interface during densification. Low temperature measurements of the thinner dielectric device indicate that lattice scattering is dominant at room temperature for the device where the densification was omitted and the excellent subthreshold slopes at low temperatures also indicate devices of good quality.
(Invited) Strained Si:C Using ClusterCarbon Implant
Authors: Sekar Karuppanan , Krull Wade
Published: April 2010

We discuss the use of ClusterCarbon implant to obtain Si:C stressor layers for strain engineering applications in advanced technology nodes. ClusterCarbon implant with its self-amorphizing capability is exploited to achieve both an abrupt and shallow junction for Phos profiles. Various carbon implant conditions are being experimented for a given phosphorus implant dose under flash and spike anneal conditions. We discuss the results to address the trade-off between phosphorus activation and carbon substitution along with the junction depth and abruptness. An optimum anneal and carbon implant condition is required to achieve higher carbon substitution along with a reasonably low sheet resistance value.
(Invited) Epitaxial Growth of Si:C Alloys: Process Development and Challenges
Authors: Dube Abhishek , Chakravarti A. , Takalkar R. , Li J. , Yang F. , Madan A. , Zhu Z. , Loesing R. , Murphy R. , Adam T. N. , Black L. R. , Holt J. R. , Harley E. C. , Stoker M. W. , Schepis D. J. , Chen X.
Published: April 2010

Uniaxial tensile strain in the channel enhances electron mobility and hence the drive current in an N-type field-effect transistor (NFET). For enhancement of NFET drive current via channel strain, the incorporation of embedded silicon carbon (eSi:C) alloys in the source/drain region has been investigated extensively. We have explored epitaxially grown embedded Si:C alloys for NFET source / drain stressor. The use of epitaxially grown intrinsic Si:C has a significant disadvantage due to incompatability with downstream processing. In situ phosphorus doped Si:C shows much more promise, especially from a strain retention perspective post growth.
(Invited) Innovative Deposition Technology for Advanced Materials
Authors: Baumann Peter K. , Heuken Michael , Weber Ulrich , Lehnen Peer , Senzaki Yoshi , Lindner Johannes , Lu Brian , Karim Ziaul , Schineller Bernd
Published: April 2010

Multi component films for a range of device applications were deposited by atomic vapor deposition (AVD®). Dysprosium doped HfO2 was studied as a high-k material. All HfDyOx films showed a tegragonal/cubic phase. A Dy concentration of 4% was determined for an optimum increase of the k-value. The material GeSbTe was investigated as a possible candidate for phase change applications. The material was deposited in a wide range of compositions in a controlled fashion. In particular the Ge2Sb2Te5 phase was achieved with good composition, thickness and electrical resistivity uniformity. Gap fill and phase change properties were studied.
Influence of Postdeposition Annealing on Physical and Electrical Properties of High-k Yb2TiO5 Gate Dielectrics
Authors: Pan Tung-Ming , Yen Li-Chen , Chiang Chien Hung , Chao Tien-Sheng
Published: April 2010

The structure and electrical properties of a high-k Yb2TiO5 gate dielectric deposited on Si(100) substrates through reactive cosputtering were investigated. X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy were used to study the morphological and chemical features of these films as functions of the growth conditions. The Yb2TiO5 dielectrics annealed at 800 oC exhibited a thinner capacitance equivalent thickness, a lowe gate leakage current, a smaller density of interface state, and a relatively lower hysteresis voltage compared to those at other annealing temperatures. These results are attributed to the formation of a rather well-crystallized Yb2TiO5 structure and composition.
Optical Characterization of Surface Profiles of Various Si1-xGex/Si Wafers Before and After Annealing Step
Authors: Yoo Woo Sik , Ueda Takeshi , Ishigaki Toshikazu , Kang Kitaek
Published: April 2010

During the steps of semiconductor processing, a wafer goes through global and local (macro and micro) surface profile and strain/stress changes due to chemical reactions and physical changes brought about by changes in the wafer's environment. In the case of Si1-xGex/Si, intentional local strain generation is introduced to enhance device performance by adding tens of atomic percents of Ge in Si. Process induced surface profile changes in TiN/NiPt/Si1-xGex/Si (100) and Si1-xGex/Si (100) wafers are characterized before and after various annealing techniques and conditions using the newly developed, very high magnification optical surface profilometry (OSP-300) system. Spike anneal steps induced significant global and local changes of wafer surface profiles in TiN/NiPt/Si1-xGex/Si (100) and Si1-xGex/Si (100) wafers, which were compared to a conventional lamp-based RTP step.