bluuebunny/crossref_metadata_2025 huggingface dataset:
Avian Migrants Facilitate Invasions of Neotropical Ticks and Tick-Borne Pathogens into the United States
Authors: Cohen Emily B. , Auckland Lisa D. , Marra Peter P. , Hamer Sarah A.
Published: October 2015

Migratory birds have the potential to transport exotic vectors and pathogens of human and animal health importance across vast distances. We systematically examined birds that recently migrated to the United States from the Neotropics for ticks. We screened both ticks and birds for tick-borne pathogens, including
Rickettsia
species and
Borrelia burgdorferi
. Over two spring seasons (2013 and 2014), 3.56% of birds (
n
= 3,844) representing 42.35% of the species examined (
n
= 85) were infested by ticks. Ground-foraging birds with reduced fuel stores were most commonly infested. Eight tick species were identified, including seven in the genus
Amblyomma
, of which only
Amblyomma maculatum/Amblyomma triste
is known to be established in the United States. Most ticks on birds (67%) were neotropical species with ranges in Central and South America. Additionally, a single
Ixodes
genus tick was detected. A total of 29% of the ticks (
n
= 137) and no avian blood samples (
n
= 100) were positive for infection with
Rickettsia
species, including
Rickettsia parkeri
, an emerging cause of spotted fever in humans in the southern United States, a species in the group of
Rickettsia
monacensis
, and uncharacterized species and endosymbionts of unknown pathogenicity. No avian tick or blood samples tested positive for
B. burgdorferi
, the etiologic agent of Lyme disease. An extrapolation of our findings suggests that anywhere from 4 to 39 million exotic neotropical ticks are transported to the United States annually on migratory songbirds, with uncertain consequences for human and animal health if the current barriers to their establishment and spread are overcome.
Adaptation of the Cecal Bacterial Microbiome of Growing Pigs in Response to Resistant Starch Type 4
Authors: Metzler-Zebeli Barbara U. , Schmitz-Esser Stephan , Mann Evelyne , Grüll Dietmar , Molnar Timea , Zebeli Qendrim
Published: October 2015

Resistant starch (RS) exacerbates health benefits on the host via modulation of the gut bacterial community. By far, these effects have been less well explored for RS of type 4. This study aimed at gaining a community-wide insight into the impact of enzymatically modified starch (EMS) on the cecal microbiota and hindgut fermentation in growing pigs. Castrated male pigs (
n
= 12/diet; 29-kg body weight) were fed diets with either 70% EMS or control starch for 10 days. The bacterial profile of each cecal sample was determined by sequencing of the V345 region of the 16S rRNA gene using the Illumina MiSeq platform. EMS diet reduced short-chain fatty acid concentrations in cecum and proximal colon compared to the control diet. Linear discriminant analyses and
K
means clustering indicated diet-specific cecal community profiles, whereby diversity and species richness were not different among diets. Pigs showed host-specific variation in their most abundant phyla,
Firmicutes
(55%),
Proteobacteria
(35%), and
Bacteroidetes
(10%). The EMS diet decreased abundance of
Ruminococcus
,
Parasutterella
,
Bilophila
,
Enterococcus
, and
Lactobacillus
operational taxonomic units (OTU), whereas
Meniscus
and
Actinobacillus
OTU were increased compared to those with the control diet (
P
< 0.05). Quantitative PCR confirmed results for host effect on
Enterobacteriaceae
and diet effect on members of the
Lactobacillus
group. The presence of less cecal short-chain fatty acids and the imputed metabolic functions of the cecal microbiome suggested that EMS was less degradable for cecal bacteria than the control starch. The present EMS effects on the bacterial community profiles were different than the previously reported RS effects and can be linked to the chemical structure of EMS.
Comparison of Switching and Biofilm Formation between
MTL
-Homozygous Strains of Candida albicans and Candida dubliniensis
Authors: Pujol Claude , Daniels Karla J. , Soll David R.
Published: October 2015

Candida albicans
and
Candida dubliniensis
are highly related species that share the same main developmental programs. In
C. albicans
, it has been demonstrated that the biofilms formed by strains heterozygous and homozygous at the mating type locus (
MTL
) differ functionally, but studies rarely identify the
MTL
configuration. This becomes a particular problem in studies of
C. dubliniensis
, given that one-third of natural strains are
MTL
homozygous. For that reason, we have analyzed
MTL
-homozygous strains of
C. dubliniensis
for their capacity to switch from white to opaque, the stability of the opaque phenotype, CO
2
induction of switching, pheromone induction of adhesion, the effects of minority opaque cells on biofilm thickness and dry weight, and biofilm architecture in comparison with
C. albicans
. Our results reveal that
C. dubliniensis
strains switch to opaque at lower average frequencies, exhibit a far lower level of opaque phase stability, are not stimulated to switch by high CO
2
, exhibit more variability in biofilm architecture, and most notably, form mature biofilms composed predominately of pseudohyphae rather than true hyphae. Therefore, while several traits of
MTL
-homozygous strains of
C. dubliniensis
appear to be degenerating or have been lost, others, most notably several related to biofilm formation, have been conserved. Within this context, the possibility is considered that
C. dubliniensis
is transitioning from a hypha-dominated to a pseudohypha-dominated biofilm and that aspects of
C. dubliniensis
colonization may provide insights into the selective pressures that are involved.
First application of cast-in-place concrete large-diameter pipe (PCC) pile-reinforced railway foundation: a field study
Authors: Zhou Mi , Liu Hanlong , Chen Yumin , Hu Yuxia
Published: October 2015

Cast-in-place concrete large-diameter pipe (PCC) piles have been widely used in highway construction for foundation reinforcement, where soft ground was encountered, due to their fast on-site construction and high capacity, hence economics. This paper reports the performance of their first application in high-speed railway foundation reinforcement on soft soil ground. To satisfy the strict settlement requirement for railway design, PCC piles with large diameters (D = 1 m), thick pile wall thicknesses (t = 0.15 m), and close spacing (s = 2.5 m) were constructed. The foundation performance has been monitored by measuring in situ foundation settlement, excess pore pressure in soil, lateral displacement of soil, and tension in the geogrid during and after embankment construction. The measurements of this project have been compared with that of a previous project when PCC piles were used. It is found that the PCC pile arrangement in this project has performed as predicted and fulfilled the strict settlement requirement set by the Chinese design guidelines.
A hump-shaped relationship between migration distance and adult pink salmon morphology suggests interactive effects of migration costs and bear predation
Authors: Sahashi Genki , Yoshiyama Taku
Published: October 2015

We examined the relationship between environmental factors of a spawning habitat and body shape at maturity in 16 pink salmon (Oncorhynchus gorbuscha) populations. The divergence vector (indicator of body depth and head size development) in both sexes was significantly correlated with distance from the sea and was described by a hump-shaped relationship. An exaggerated body shape was most developed at mid-distance from the sea and less developed both near and far from the sea. The observed frequency of bears decreased significantly with distance from the sea, implying that bear predation on salmon is most intense near the sea. Therefore, our results imply that shape-selective predation by bears affects the shape of pink salmon in rivers where the spawning habitat is near the sea and that migration costs inhibit development of an exaggerated body depth and head size in salmon in rivers where the spawning habitat is far from the sea.
Major sinks of the Changjiang (Yangtze River)-derived sediments in the East China Sea during the late Quaternary
Authors: Yang Shouye , Bi Lei , Li Chao , Wang Zhongbo , Dou Yanguang
Published: October 2015

The East China Sea (ECS) is a typical marginal sea located between the Eurasian continent and west Pacific Ocean. In this study, we review state-of-the-art research progress on the possible sinks of the Changjiang-derived sediments in the ECS during the late Quaternary. The major sinks of these sediments in the ECS are on the outer shelf and the Okinawa Trough during the last glacial maximum corresponding to a lowstand of sea level. During the deglacial marine transgression, the gently dipping shelf was rapidly inundated and strong tides prevented fine sediment from deposition on the open shelf, resulting in the development of a unique tidal sand ridge system. With sea level reaching the present situation and the modern marine environment being completed in the early Holocene, the Changjiang sediments mostly accumulated in the river's estuary to build a large delta, with only a fraction reaching the inner shelf and coastal embayments. The late-Quaternary changes in monsoon-climate-induced river flux, sea level and oceanic circulation primarily controlled the source-to-sink transport of the Changjiang sediments in the ECS, and further determined the stratigraphic framework and sedimentary facies on the shelf.
Stratigraphic variations in the Diaokou lobe area of the Yellow River delta, China: implications for an evolutionary model of a delta lobe
Authors: Wang Yonghong , Liu Xiujin , Li Guangxue , Zhang Weiguo
Published: October 2015

Characterization of the evolution of delta lobes has theoretical significance for the formation of entire deltas. The Diaokou lobe of the Yellow River delta provides a typical example. The Yellow River transported a great deal of sediment to the Diaokou area during the period of 1964–76 after the river changed its course to the Diaokou River and formed a new delta lobe – the Diaokou lobe. The Diaokou lobe reflects the evolution of the modern Yellow River delta and contains a record that represents the complete modern Yellow River delta depositional system. Using grain-size characteristics, magnetism, and the accelerator mass spectrometry (AMS)
14
C dating of cores ZK10-3 and ZK30 in the northern part of the Diaokou lobe, combined with collected data from cores ZK227, ZK1 and ZK228, which are located further south on the Diaokou lobe, we analysed the Holocene and recent stratigraphy of the Diaokou lobe area and its evolution. The Holocene stratigraphy of the Diaokou lobe and the nearby area contains upwards-succession, shallow-marine, river and lake, salt-marsh, and delta facies. This area received deltaic deposits beginning in 1855 and experienced prodelta, delta-front (lateral) and delta-plain deposition. When the Diaokou lobe began to form, this area experienced four stages of deposition after 1964: (1) dispersed-flow deposition; (2) single-channel deposition; (3) diversion deposition; and (4) abandonment and erosion. Compared with the evolution of a lobe of the Mississippi delta, the Yellow River delta contains thick, laterally extensive deposits as a result of the higher sediment load.
Lithium Plating and Stripping in the Framework of a 3D Electrochemical Model
Authors: Hein Simon , Latz Arnulf
Published: October 2015

One of the major degradation processes in lithium-ion batteries is lithium plating. This mechanism describes the growth of a parasitic metallic lithium phase on the surface of the negative electrode. We present an extension to a 3D transport model, which allows for deposition and dissolution of an additional metallic lithium phase inside of a lithium-ion battery. The effect of lithium stripping and plating on the cell voltage can be investigated.
Mesoscale Modeling and Simulation of Composition, Manufacturing, and Microstructure Effects on Electrical Conduction in Thermal Battery Cathodes
Authors: Reinholz Emilee Lolita , Roberts Scott A. , Schunk P. Randall , Apblett Christopher A.
Published: October 2015

Li/FeS2 thermal batteries provide a stable, robust, and reliable power source capable of long-term electrical energy storage without performance degradation. These systems rely on the electrical conductivity of FeS2 cathodes for critical performance parameters such as power and lifetime, and on permeability of the electrolyte through the solid FeS2 particles for ion transfer. The effects of component composition, manufacturing conditions, and the mechanical deformation on conductivity and permeability have not been studied. We present simulation results from a finite element computer model compared with impedance spectroscopy electrical conductivity experiments. Our methods elucidate the combined effects of slumping, particle size distribution, composition, and pellet density on properties related to electrical conduction in Li/FeS2 thermal battery cathodes.
Analyzing Capacitive Characteristics of Lithium-Ion Batteries Using a Distribution Function of the Differential Capacity
Authors: Schoenleber Michael , Ivers-Tiffée Ellen
Published: October 2015

A generalization of the concept of the Distribution Function of Relaxation Times (DRT) for capacitive systems, the Distribution Function of the Differential Capacity (DDC) is presented. While the DRT describes correctly how different polarization processes build up after applying a current step, due to its underlying model structure it does not carry information about the intercalation of species into the electrode. The latter is described by the proposed DDC, which states at a given SOC (i) how much capacity there is, (ii) from how many components it is composed and (iii) how fast these components can be discharged.
A Computational Model for Sodium Sulfur Battery Analysis
Authors: Sezer Hayri , Aygun Mehmet , Mason Jerry Hunter , Baran Engin , Celik Ismail Bektas
Published: October 2015

Energy storage from the renewable energy sources is one of the challenging issue of clean energy technologies. Recently, sodium sulfur (Na-S) battery has gained considerable attention as a viable candidate of energy storage application. However, Na-S battery technology comes with the disadvantages of relatively high temperature operating conditions, brittle insulator and safety concern with regarded to temperature management. In this study, a two-dimensional heat transfer model is integrated with a zero-dimensional, transient electrochemical model for Na-S batteries to predict the temperature distribution inside the Na-S battery under cell operating conditions. Properties required for solving the heat transfer governing equation and electrochemical model, such as electronic and ionic conductivity, species concentrations and heat conductivity are calculated and updated as a function of time. Additionally, the instant outputs of these combined computational tools for single sodium sulfur battery, temperature, open circuit voltage, polarization and ohmic losses are used as input values for a designed Simulink model to analyze a stack of Na-S batteries. These computational tools aim to enable the thermal management and to a complete design procedure of storage systems made of Na-S batteries. The present model is tested against experimental results found in literature. Good agreement is achieved between current model and the available experiments. Validated model is used to perform a parametric study.
Dielectric Properties of Ethylene Carbonate and Propylene Carbonate Using Molecular Dynamics Simulations
Authors: You Xinli , Chaudhari Mangesh , Rempe Susan , Pratt Lawrence R
Published: October 2015

Ethylene carbonate (EC) and propylene carbonate (PC) are widely used solvents in Li-ion batteries and supercapacitors. Ion %LRP solvation dissolution anddiffusion in those media are correlated with solvent dielectric %lrp propertiesresponses. %LRP usedHere, we use all-atom molecular dynamics simulations of the pure solvents to calculatedielectric constants and relaxation times. The dielectric constantmeasures polarization of a materialby a static applied field while the relaxation assesses the lag ofthe polarization in responding to a changing applied field. Predicted valuesare compared with the available experimental results to validate the force fieldparameters (OPLS-AA) for these solvents. Results for dielectric constants andrelaxation times agree with experiment for both EC and PC.
(Invited) Challenges with Quantum Chemistry-Based Screening of Electrochemical Stability of Lithium Battery Electrolytes
Authors: Borodin Oleg , Olguin Marco , Spear Carrie , Leiter Kenneth , Knap Jaroslaw , Yushin Gleb , Childs Adam , Xu Kang
Published: October 2015

Challenges with the quantum chemistry based-screening of electrochemical stability of solvents and salts with potential applications in lithium batteries are discussed. Initial high throughput screening of carbonate and phosphate-based electrolyte solvents provided insight into first and second reduction and oxidation potentials and reorganization energies of these solvents. It has been found that it was important to include a lithium cation in the screening of semifluorinated solvents. Two reduction pathways has been found for lithium complexed with semifluorinated solvents and salts such as lithium bis(fluorosulfonyl)imide (LiFSI): the low rate defluorination reaction occurring at high potentials and fast solvent or anion reduction occurring at significantly lower potentials. A spontaneous deprotonation of carbonate solvents at the surface of the completely de-lithiated LiNi0.5Mn1.5O4 cathode has been found.
Simulation and Modelling of the Solid Electrolyte Interphase with Varying Porosity
Authors: Single Fabian , Karaca Erkmen , Horstmann Birger , Latz Arnulf
Published: October 2015

We extend a popular approach in SEI modeling by refraining from using a single reaction interface. Instead we trace the time evolution of the SEI volume fraction in a spatially resolved way. In this study, we test how neutral lithium interstitial diffusion can explain the continuous growth of the SEI. We observe that transport of neutral lithium interstitials, as estimated by DFT calculation, is too slow to explain the growth of SEI layers with several tens of nanometer thickness. In future work, this spatially resolved transport and reaction framework will be used to study more realistic transport mechanisms.
(Invited) Porous Silicon Studies of Prof. Yukio H. Ogata
Authors: Sakka Tetsuo , Fukami Kazuhiro
Published: October 2015

Professor Yukio H. Ogata was an outstanding researcher and a reliable leader of the research group. This article is to remember him and his great contribution to Pits & Pores and porous silicon community.
(Invited) Electrodeposition in Microporous Silicon from the Viewpoint of Hydration Property: Effect of Coexisting Ions in Zinc Electrodeposition
Authors: Fukami Kazuhiro , Koda Ryo , Koyama Akira , Sakka Tetsuo , Abe Takeshi , Kitada Atsushi , Murase Kuniaki
Published: October 2015

Electrodeposition of zinc in nanoporous silicon electrodes was studied in detail. In an earlier study, we have reported that coexisting counter ions have an impact on electrodeposition behavior of platinum within nanoporous silicon. In the present study, we investigate that the effect of counter ions on zinc electrodeposition within nanoporous silicon. It has been clarified that the deposition behavior of zinc is dependent upon the counter anions. The deposition behavior is discussed based on the density of nucleation at the initial stage of the deposition.
Effect of Displacement Deposition on Platinum Deposition within Nanoporous Silicon
Authors: Koyama Akira , Fukami Kazuhiro , Koda Ryo , Sakka Tetsuo , Abe Takeshi , Kitada Atsushi , Murase Kuniaki
Published: October 2015

The contribution of platinum (Pt) displacement deposition within the nanoporous silicon (Si) electrode during electrodepostion is reported. Time variations of the amount of Pt deposits reveal that the displacement deposition preferentially proceeds within the nanopores during electrodeposition. Sufficiently thick porous layer promotes the Si oxidation reaction due to its large oxidizable areas. This leads to fast displacement deposition that results in the unfavorable plugging at the pore opening. Pre-anodization of porous silicon suppresses the displacement deposition to some extent and enables the penetration of Pt complex anions without the obstruction by the plugging.
(Invited) Silicon Electrochemical Micromachining Technology: The Good, the Bad and the Future
Authors: Barillaro Giuseppe
Published: October 2015

Electrochemical micromachining (ECM) is a highly flexible technology allowing for accurate fabrication of both simple microstructures (e.g. macropores, microtips, spirals) and complex microsystems (e.g. microgrippers, microneedles) in silicon at low cost, in any lab. In this paper main advantages and drawbacks of ECM technology are discussed, also with respect to standard leading micromachining technology, and future directions for ECM advance are given.
Porous Silicon Nanoneedles By Metal Assisted Chemical Etch for Intracellular Sensing and Delivery
Authors: Chiappini Ciro , De Rosa Enrica , Martinez Jonathan Otto , Campagnolo Paola , Almeida Carina , Tasciotti Ennio , Stevens Molly
Published: October 2015

Metal assisted chemical etch has recently come to prominence as a versatile strategy for the realization of silicon nanostructures with tailored porosity. By exploiting metal assisted chemical etch, we recently developed porous silicon nanoneedles capable of interfacing with cells for delivery to and sensing of the intracellular milieu. Here we review our recently published studies on the fabrication of such nanostructures. Further we review their use as vectors for the localized delivery nucleic acids capable of inducing neovasculature formation in a mouse model. Finally we provide an overview of our findings on the use of porous silicon nanoneedles as intracellular sensors for detection of enzymatic activity with high resolution across excised human tissue samples.
(Invited) Pore Filling of Porous Silicon with Ferromagnetic Nanostructures
Authors: Rumpf Klemens , Granitzer Petra , Poelt Peter , Michor Herwig
Published: October 2015

Within this work the deposition of ferromagnetic metals in high aspect ratio mesopores will be elucidated regarding the specific nucleation and growth of the deposited nanostructures under various conditions. Since mesoporous morphologies offer dendritic pore walls these structural inhomogeneities of the matrices are critical for the deposition process. Experiments show that the nucleation preferentially starts at the “tops” of the rough surface. A further key point of the presentation is the magnetic characterization of the various nanocomposites. Magnetic characterization of the systems shows that not only the morphology of the deposited metal structures (size, shape, distribution) determines the magnetic properties but also the morphology of the template (side-pore length). In this sense magnetic coupling between the nanostructures plays a crucial role and is strongly influenced by morphological parameters. From all these findings it is possible to prepare samples with specific magnetic properties which could be of interest for on-the-chip devices.
Magnetic Studies of Iron Oxide Nanoparticles Encapsulated within Nanostructured Silicon
Authors: Granitzer Petra , Rumpf Klemens , Gonzalez-Rodriguez Roberto , Coffer Jeffery , Poelt Peter , Reissner Michael
Published: October 2015

In the frame of this work the structural and magnetic characterization of encapsulated iron oxide nanoparticles within a nanostructured silicon host is discussed. Two approaches are depicted, one to infiltrate readily synthesized Fe3O4 particles into the pores and second to grow iron oxide inside the pores out of an ethanolic iron salt solution. Beside the particle size dependent investigations, a key point of the presentation is the optimization of the system with respect to the desired magnetic properties (magnetic moment as high as possible, blocking temperature below room temperature) which are controlled by the filling parameters as well as by the morphology of the host. All investigated composite systems exhibit a blocking temperature far below room temperature and due to the fact that all utilized materials are biocompatible the presented systems are promising for using as magnetic vehicle in biomedicine.
Morphological and Optical Properties of Stain Etched Silicon in Vanadium Oxide (V2O5) / Hydrofluoric Acid (HF) Solution
Authors: Ayat Maha , Gabouze Noureddine , Sam Sabrina , Boarino Luca , Boukherroub Rabah
Published: October 2015

In this work we report the fabrication of ordered macroporous silicion structures by chemical etching of silicon in vanadium oxide (V2O5) and hydrofluoric acid (HF) solution. The effects of the different etching parameters, including the etching time and the presence of metal catalyst film deposition (Pd, Ag), on the morphologies and the optical properties of the etched Si surfaces were studied. It has been found that the morphology depends on the etching time and on the presence and the type of the catalyst. The results show that the attack of the silicon surface coated with Palladium or Silver deposit begins by creating circular pores. In addition, long etching time leads to the formation of porous pyramidal structures inside the macropores. A reflectance around 1,64% and a contact angle of 148° for the Ag/Si structures were observed.
(Invited) Bright Light Emitting Silicon/Germanium Nanostructures
Authors: Lockwood David J
Published: October 2015

Light emission from Si nanostructures has been of great interest for some time now owing to the need for silicon-based light sources for applications in silicon opto-electronics and photonics. Both Si and Ge possess indirect band gaps, which makes them very inefficient light emitters. Band gap engineering employing quantum wells or quantum dots has been proposed as one way to overcome this limitation and Si/Ge or Si/SiGe-alloy thin-multilayer nanostructures grown on Si have been produced on this principle, and although light emission with greatly improved efficiency has been obtained at low temperatures the emission at room temperature is still very weak, because of exciton dissociation. Recent advances in band gap engineering technology have resulted in the development of new systems incorporating one-, two-, and three-dimensionally confined Si-Ge nanostructures that produce bright light in the near infrared. Here, the novel optical properties of three such nanostructures – super unit cells, nanowires, and nanocluster layers – are explored.
(Invited) Electronic and Acoustic Applications of Anodized Nano-Crystalline Silicon
Authors: Koshida Nobuyoshi
Published: October 2015

Anodized nano-crystalline silicon (nc-Si) layer is one of the self-organized Si nanostructures formed by electrochemical process. In addition to efficient luminescence, many specific effects are induced in nc-Si. For instance, the enhanced electron transport and the decreased thermal conduction lead to emission of ballistic electrons and acoustic wave, respectively. It is shown here that the ballistic electron emitter is useful for mask-less parallel lithography under an active-matrix drive mode. Also, injection of emitted energetic electrons into metal-salt solutions promotes reduction of positive ions and subsequent thin film deposition. On the other hand, the extremely lowered thermal conductivity and heat capacity of nc-Si layer enable efficient thermos-acoustic conversion at the surface. Being a broad-band flat ultrasound emission with no resonant peaks, the device can reproduce well the complicated acoustic communication calls between mice.
Plasmonic Mesostructures Prepared by Oriented Mesoporous Materials as a Template
Authors: Murai Shunsuke , Uno Shiguma , Kamakura Ryosuke , Fujita Koji , Tanaka Katsuhisa
Published: October 2015

Highly-oriented mesoporous silica thin film was used as a template to fabricate metallic meso-structures. Oblique angle deposition of gold on the thin film results in the discrete gold meso-gratings with rod-like islands aligning along the meso-cylinders of silica. The optical transmission of the gold meso-gratings is highly sensitiveto the polarization of incident light, reflecting its anisotropic morphology.
Porous Silicon in Microelectronics: From Academic Studies to Industry
Authors: Gautier Gael , Defforge Thomas , Desplobain Sebastien , Billoué Jérôme , Capelle Marie , Povéda Patrick , Vanga Kumar , Lu Bin , Bardet Benjamin , Lascaud Julie , Seck Cheikhou , Fèvre Angélique , Menard Samuel , Ventura Laurent
Published: October 2015

The evolution of porous silicon (PSi) from its early studies in the late 70’s toward its industrial application in microelectronics is described in this article. The way this material can be integrated now in many devices at a wafer level is shown in this paper through examples of prototypes that include PSi in their fabrication process. For instance, realization of devices on large area wafers in the field of RF passive components, energy micro-sources or porous flexible membranes are described. In this paper, we also show recent advances in the field of PSi etching and integration at an industrial level. In particular, we put an emphasis on reproducibility and homogeneity issues, on the wafer warp management using different annealing procedures.
Bias-dependent Photoabsorption Properties of GaN Porous Structures under Back-side Illumination
Authors: Sato Taketomo , Kida Hirofumi , Kumazaki Yusuke , Yatabe Zenji
Published: October 2015

Photoabsorption properties of GaN porous structures were investigated by measuring photocurrent and transmittance under monochromatic light with various wavelengths. The measured photocurrents on the porous GaN electrode were larger than those on the planar electrodes, and those were observed even under illumination with lower photon energy than the bandgap energy of bulk GaN. Moreover, the light transmittance that was measured in the back-side illumination (BSI) mode depended strongly on the applied voltage to the porous electrode with change of the photocurrents. The observed photoabsorption properties can be qualitatively explained by the Franz-Keldysh effect; namely, the high electric field induced in the GaN porous structure easily causes a redshift of the photoabsorption edge.
(Invited) Thermal Carbonization of Porous Silicon: The Current Status and Recent Applications
Authors: Salonen Jarno , Kaasalainen Martti , Rauhala Olli-Pekka , Lassila Lippo , Hakamies Martta , Jalkanen Tero , Hahn Robert , Schmuki P. , Mäkilä Ermei
Published: October 2015

The current status and recent new applications of thermally carbonized porous silicon (TCPSi) are discussed in this paper. The basic physicochemical properties of TCPSi, relevant to the applications, are also described and new information related to mechanical, electrical and optical properties of TCPSi is introduced. Also, the further functionalization of thermally carbonized PSi is described.
Optical Property of Porous Silicon Produced by Metal-Assisted Etching
Authors: Yamakawa Kano , Sakamoto Susumu , Fukumuro Naoki , Yae Shinji
Published: October 2015

Antireflection of Si surface is an important technology to increase the photocurrent density of solar cells. Recently, porous Si has been researched for replacing Si nitride which is common material of antireflective coating (ARC). In this study, we have investigated the optical properties of porous Si thin films, thinner than doped layers for p-n junction formation of Si solar cells, produced by metal-assisted etching. The structure of porous Si is changed with the size of catalytic Ag nanoparticles, composition of etching solution, and etching time. The reflection of porous film formed Si wafers is much lower than that of mirror polished wafers. Reflectance spectra and ellipsometric analysis indicate that the thin porous Si films act as optical films and they are expected to function as suitable ARC for crystalline Si solar cells.
Functional Optical Devices Based on Highly Ordered Metal Nanostructures Obtained Using Anodic Porous Alumina
Authors: Kondo Toshiaki , Yanagishita Takashi , Masuda Hideki
Published: October 2015

The fabrication of an array of square metal nanodots using anodic porous alumina as an evaporation mask and its application to a substrate for surface-enhanced Raman scattering (SERS) measurement are described in detail. The nanodot shape could be controlled by changing the shape of the nanoholes in the anodic porous alumina. The obtained Au nanodot array could be applied to a substrate for SERS measurement with high sensitivity. It is expected that this process can be applied to fabricate not only highly ordered metal nanodot arrays but also functional optical devices.
Silicon Nanowires Self-Purification By Metal-Assisted Chemical Etching of Metallurgical Silicon
Authors: Schweizer Stefan L. , Li Xiaopeng , Wang Junna , Sprafke Alexander , Wehrspohn Ralf B.
Published: October 2015

The purity of metallurgical-grade silicon can be increased to solar grade by metal-assisted chemical etching (MaCE). Metal impurities are removed during the formation of porous silicon nanowires (NW). We present a chemical etching model to explain the different levels of chemical reduction for various metals with pore growth during etching. Our study not only highlights the importance of controlling the metal ion concentration and selecting metal types for engineering porous features in NWs, but also explains the reason for the difficulty in removing noble metals such as Cu.
(Keynote) Oxide based Resistive Memories for Low Power Embedded Applications and Neuromorphic Systems
Authors: Vianello Elisa , Garbin Daniele , Jovanovic Natalija , Bichler Olivier , Thomas Olivier , de Salvo Barbara , Perniola Luca
Published: October 2015

Oxide based resistive memories (OxRAMs) is one of the potential candidates for non-volatile logic circuits and neuromorphic circuits in the applications of wearable devices, internet of things (IoT), cloud computing, and big-data processing. One of the main OxRAMs issue is the noise behavior of the high resistance state (HRS). In this work, we will demonstrate a hybrid (CMOS logic plus ReRAM devices) Non Volatile Flip Flop designed to face OxRAM variability. Concerning neuromorphic circuits, we will focus on the impact of resistance variability on the performance of Convolutional Neural Network (CNN) systems for visual pattern recognition applications.
(Invited) Simulation and Modeling of the Switching Dynamics in Resistive Switching Devices
Authors: Menzel Stephan
Published: October 2015

Resistive switching devices based on the electrochemical mechanism (ECM) or the valence change mechanism (VCM) have attracted great attention due to their potential use in future non-volatile memories. The paper presents physics-based simulation models for ECM and VCM cells that can reproduce the key switching phenomena: I-V characteristics, highly nonlinear switching kinetics and multilevel switching. The physical processes that lead to the nonlinear switching kinetics will be discussed in detail.
(Invited) Simulating the Behavior of a Bipolar Filamentary ReRAM Cell for Upcoming Memory Devices
Authors: Wicklein Sebastian , Petti C , Minville T , Bandyopadhyay A , Ilkbahar A
Published: October 2015

The fundamental processes of a filamentary bipolar ReRAM cell were investigated using finite element simulation tools. The Forming, Set and Reset processes were simulated. All processes were simulated considering the migration of ionic species. Different scenarios for forming were considered and seem feasible. The reset and set process showed that different scenarios are possible however bipolar characteristic cannot be simulated entirely by considering the migration of ionic species and charged defects alone.
Multilevel Resistive Switching with Oxygen Vacancy Filaments in Pt/TaOx/Cu and Pt/TaOx/Pt Devices
Authors: Kang Yuhong , Ghosh Gargi , Orlowski Marius K
Published: October 2015

It is demonstrated that multilevel switching of oxygen vacancy (Vo) conductive filaments (CF) is characterized by the relation Ron=A/Icc
n between ON-state resistance (Ron) and compliance current (Icc). In contrast to metallic (Cu, Ag) CFs, where the exponent n for various devices is found universally to be n ≈ 1, we find n=1.36 for Vo CFs. An exponent n>1 may imply two distinct mechanisms responsible for the formation of Vo CFs. 1st mechanism is similar to the formation mechanism for metallic CFs and accounts for the unity part of the exponent, while the 2nd mechanism is responsible for the remainder (n-1). This hypothesis is corroborated by data of Vo CFs in resistive switching cells with and without active electrodes such as Pt/TaOx/Cu and Pt/TaOx/Pt and also on Pt/SiO2/Cu and Pt/SiO2/Pt devices.
(Invited) Resistive Random Access Memory for Storage Class Applications
Authors: Jo Sung Hyun , Kumar Tanmay
Published: October 2015

The suppression of sneak paths in a cross-point RRAM array, one of the most challenging tasks in high density RRAM integration, has been successfully demonstrated by utilizing a Field Assisted Superlinear Threshold (FAST) selector. The FAST selector provides a volatile switching behavior at the critical electric field. Excellent selector performance is presented, including high selectivity of > 107, sharp switching slope of < 5mV/dec., and large endurance of > 1011. Furthermore, the volatile switch based selector offers various benefits such as small operation voltage overhead in the 1S1R (1 selector 1 resistor) integration, large sensing margin and increased memory ON/OFF ratio.
(Invited) Mechanism Study of Reversible Resistivity Change in Oxide Thin Film
Authors: Hong Seungbum , Chang Seo Hyoung , Phatak Charudatta , Magyari-Kope Blanka , Nishi Yoshio , Chattopadhyay Soma , Kim Jung Ho
Published: October 2015

Here we present our findings related to the mechanism of reversible resistivity in Pt/TiO2/Pt cells and in Ta2O5 thin films. Our findings for Pt/TiO2/Pt cells indicate that there exists a photovoltaic-like effect, which modulates the resistance reversibly by a few orders of magnitude, depending on the intensity of impinging x-rays. We found that this effect, combined with the xray irradiation induced phase transition confirmed by transmission electron microscopy, triggers a non-volatile reversible resistance change. For Ta2O5 thin films, we found that there are strong correlations among oxygen vacancy number and positions and energy gaps. Ab initio band structure calculations explain the evolution of the electronic excitation spectrum as a function of oxygen vacancy number and positions and importantly provide a predictive description of the oxygen deficient Ta oxide that may improve the desired performance based on atomic level design.
(Keynote) Nanoscale Memories: What Does Physics Have to Say?
Authors: Zhirnov Victor V. , Meade R , Pandey S. C. , Sandhu G
Published: October 2015

The central question addressed in this paper is: What is the smallest volume of matter needed for memory devices? It will be shown that, at least in principle, 1-nm devices can be envisioned, which are based on the re-arrangement of atoms; examples include atomic/ionic switches and resistive memory (ReRAM). While theoretical feasibility of the 1-nm devices has been justified based on electrical properties of the few-atom systems, it is still an open question whether such small structure could have sufficient thermal stability for reliable operation. For example, Joule heat will be released as the current passes through the structure, which can potentially destroy the few-atom conductive bridge (CB). In this paper, initial studies of thermal properties of atomic contacts and nanoscale interfaces are presented.
(Invited) Integration Challenges of Ferroelectric Hafnium Oxide Based Embedded Memory
Authors: Müller Johannes , Polakowski Patrick , Paul Jan , Riedel Stefan , Hoffmann Raik , Drescher Maximilian , Slesazeck Stefan , Müller Stefan , Mulaosmanovic Halid , Schröder Uwe , Mikolajick Thomas , Flachowsky Stefan , Erben Elke , Smith Elliot , Binder Robert , Triyoso Dina , Metzger Joachim , Kolodinski Sabine
Published: October 2015

One of the key challenges in the development of embedded memory solutions is to ensure their compatibility to CMOS processing and to reduce the added complexity to a minimum. Especially the parallel implementation of charge based one-transistor memories in the FEoL, such as e.g. floating gate devices, together with advanced transistor technologies proves rather challenging. In contrast to that, an alternative one-transistor memory concept based on ferroelectric hafnium oxide closely resembles state of the art high-k metal gate devices and therewith promises a greatly simplified integration. Here we investigate the impact of strain, thermal budget and work function engineering, usually applied to high-k metal gate technologies, on material properties as well as on the memory performance of hafnium oxide based ferroelectric field effect transistors. Key challenges related to a modified gate etch and the integration of different hafnium oxide thicknesses will be discussed.
Characterization of Low-Dielectric Constant Silicon Carbonitride (SiCN) Dielectric Films for Charge Trapping Nonvolatile Memories
Authors: Ahmed Sheikh Rashel AL , Naito Shinji , Kobayashi Kiyoteru
Published: October 2015

We investigated the charge retention characteristics of the charge-trapping type memory capacitors with blocking oxide-SiCN-tunneling oxide stacked films at four different temperatures. Long-term data retention more than 10 years was estimated at 85 °C for the SiCN memory capacitors. We presented a simple method to analyze the energy distribution of trap states inside the SiCN layer. The trapped electrons were estimated to be distributed from 0.8 to 1.3 eV below the conduction band edge in the SiCN band gap.
Resistance Switching Phenomenon Associated with Anisotropic Magnetoresistance of the ReRAM Device with Ferromagnetic Electrodes
Authors: Ito Daisuke , Yoshida Hayato , Shimizu Tomohiro , Shingubara Shoso
Published: October 2015

We fabricated a ReRAM device which has a HfOx dielectric layer sandwiched with two ferromagnetic electrodes of Ni and FeNi. The device shows bipolar resistance switching characteristics such that SET operation occurs when positive bias is applied to Ni electrode. Fluctuation of switching voltages of the device was smaller than that of the Ni/HfOx/Pt device. We observed anisotropic magnetoresistance phenomenon in the LRS (low resistance state). There were step-like resistance changes in MR property, which may corresponded to formation and annihilation of domain in the ferromagnetic conductive filament.
(Keynote) Status and Challenges in Spin-Transfer Torque MRAM Technology
Authors: Krounbi Mohamad , Nikitin Vladimir , Apalkov Dmytro , Lee Jangeun , Tang Xueti , Beach Robert , Erickson Dustin , Chen Eugene
Published: October 2015

Perpendicular MTJ based Spin-Transfer Torque Magneto-resistive Random Access Memory (STT-MRAM) has been considered as a promising candidate for next generation non-volatile memory due to a combination of fast speed, high endurance, excellent scalability, and ease of integration with the standard CMOS processes. Despite significant progress, there are many remaining hurdles in its productization. They are stemming from a set of requirements imposed on the MTJ performance: simultaneously high magneto-resistance at low RA (Resistance x Area) product, low writing current/voltage and high thermal stability, low write and read error rates and high endurance cycles. We will discuss the inter-dependencies of these parameters, report our progress in meeting these requirements, and our development approaches for future challenges.
Critical BEOL Aspects of the Fabrication of a Thermally-Assisted MRAM Device
Authors: O'Sullivan E. J. , Edelstein Daniel , Marchack Nathan , Lofaro Michael , Gaidis Michael , Joseph Eric , Annunziata Anthony , Pfeiffer Dirk , Trouilloud P. L. , Zhu Yu , Holmes Steve , Galan Armand , Pyzna Adam M. , Gonsalves Jemima
Published: October 2015

Recent developments in new switching methods, such as spin transfer torque and temperature-assisted switching (TAS), have greatly increased interest in MRAM. However, MRAM fabrication is challenging due to the lack of magnetic materials processing experience by semiconductor lines. In this talk, we will discuss key BEOL fabrication aspects for a CMOS-integrated TAS MRAM on 200 mm wafers with, e.g., opens/shorts yields of 100% and 99% for 1 Mb and 16 Mb arrays, resp. This was achieved in our R&D line through careful process optimization and adherence to good BEOL processing.
(Invited) CH3NH3PbI3 Perovskite Solar Cells on Inorganic Materials: CuSCN and Crystal Silicon
Authors: Ito Seigo
Published: October 2015

Organo-lead halide perovskites have attracted much attention for solar cell applications due to their unique optical and electrical properties. With either low-temperature solution processing or vacuum evaporation, the overall conversion efficiencies of perovskite solar cells with organic hole-transporting material were quickly improved to over 15% during the last 3 years. However, the organic hole-transporting materials used are normally quite expensive due to complicated synthetic procedure or high-purity requirement. Here, we demonstrate the application of an effective and cheap inorganic p-type hole-transporting material, copper thiocyanate, on lead halide perovskite-based devices. With low-temperature solution-process deposition method, a power conversion efficiency of 12% was achieved under full sun illumination. Moreover, PECVE-free c-Si solar cells will be presented for utilization of tandem device with perovskite solar cells.
(Invited) Potential and Activities of III-V/Si Tandem Solar Cells
Authors: Yamaguchi Masafumi , Lee K-H , Araki K , Kojima N , Ohshita Y
Published: October 2015

The paper presents efficiency potential of III-V/Si tandem solar cells with efficiencies of more than 35% under 1-sun AM1.5G and effects of dislocation upon solar cell properties of III-V-on-Si single-junction solar cells and III-V/Si tandem solar cells. Because III-V/Si system has large lattice mismatching and difference in thermal expansion coefficient, generation of misfit and thermal stress induced dislocations affect on solar cell properties. Effects of dislocations upon minority-carrier lifetime are derived from considering one dimensional transport of minority carriers to dislocations. In order to realize high efficiency solar cells with similar efficiency by homo-epitaxially grown solar cells, low density dislocation of less than 3x105 cm-2 is necessary. This paper also reviews approaches on reduction in dislocation density in III-V compound films on Si and improvements in efficiencies of III-V compound single-junction solar cells on Si substrates and III-V/Si tandem solar cells.
Fabrication and Characterization of Hybrid Solar Cells Based on Perovskite Materials
Authors: Abdel-Fattah Tarek M , Ebrahim Shaker , Soliman M , Anas M , Moustafa E
Published: October 2015

The aim of this study is to prepare and characterize the perovskite as hole transferring and electron transferring materials to be used in the fabrication of solar cells. Inverted perovskite solar cells have been fabricated with the following design: fluorine tin oxide (FTO)/electron injection layer (EIL)/active layer/hole injection layer (HIL)/metallic upper electrode. CuI as hole injection material matched the energy levels with FTO. ZnO nanoparticles was prepared by sol gel method and used as electron injection layer. Aging the ZnO sol for one month yields a better cell performance due to the formation of nanoridges structure. The achievable perovskite solar cell efficiency, fill factor, open circuit voltage and short circuit current density were found to be 2.4%, 0.67, 1.0 V and 0.037 mA/cm2, respectively for the following device structure: FTO/ZnO/CH3NH2PbI3/CuI/Au.