bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Relation between the Fine Structural Change and Color Fading in the Natural Mineral Pigments Azurite and Malachite
Authors: Nishimura Ryoichi , Ide-Ektessabi Ari 
Published: April 2011

AbstractMany ancient Asian and Japanese paintings have been drawn with natural mineral pigments. The discoloring mechanism of these pigments has been a real concern for the characterization, restoration and preservation of the ancient cultural properties. The authors expect that the color fading is deeply related with the chemical composition and the fine structural change of the major elements. Therefore the purpose of this paper is to make clear the relation between the fine structural change and color fading.We analyzed several representative pigments of Japan, including copper carbonate hydroxide pigments (blue verditer and green verditer, “gunjo” and “ryokusho” called in Japanese) by x-ray fluorescence analysis (XRF) and x-ray absorption fine structure (XAFS). In order to examine the deterioration of pigments, some of them were exposed in the highly-heated condition. In addition, the spectral reflectivity data are also collected on spectrophotometer system.Here we propose to compare the results obtained from XRF and XAFS with the spectral reflectivity data. The results demonstrate that the chemical composition and the fine structural change can provide valuable information for revealing the discoloring mechanism, which would then lead to the original color estimation of the ancient cultural properties.
Collaboration or Appropriation? Examining a 17th c. Panel by David Teniers the Younger and Jan Brueghel the Younger Using Confocal X-Ray Fluorescence Microscopy
Authors: Mass Jennifer L. , Woll Arthur R. , Ocon Noelle , Bisulca Christina , Wazny Tomasz , Griggs Carol B. , Cushman Matt 
Published: April 2011

AbstractThe 17th c. Flemish painting on panel, The Armorer's Shop, has long been attributed to David Teniers the Younger (1610-1690). The painting depicts an opulent pile of parade armor at the bottom left foreground, a seated armorer at the bottom right foreground, and a forge surrounded by workers in the middle ground. The Teniers attribution is derived from his signature at the bottom right as well as figural groups and other visual elements that are commonly associated with him and executed in his style. During dendrochronological examination of the painting, a portion of the oak plank comprising the overall structure was found to have been carved out so that a smaller plank (containing the parade armor) could be inserted into the resulting depression. This unusual construction, combined with the identification of several paintings by Jan Brueghel the Younger (1601-1678) depicting the same parade armor, raised questions about the attribution and chronology of construction of the painting. Art historical research suggests that the smaller plank with the armor was painted by Brueghel and that the remainder of the panel with the workers and forge was painted by his brother-in-law Teniers. While Brueghel writes of collaborating with Teniers in his journal, this appears to be the only identified collaboration of the two artists. Conventional microanalysis methods did not resolve the painting's construction chronology. However, confocal x-ray fluorescence microscopy (CXRF) revealed the composition and location of buried paint layers at the panel interfaces by combining depth scans at a number of adjacent lateral positions to produce virtual cross-sections over 20 mm in length. The relationship of the paint layers at the panel interfaces provided evidence for the armor panel having been painted separately and prior to the rest of the composition. This data, along with dendrochronological and IRR data, provided a chronology of construction for the painting that provided additional evidence for a Brueghel attribution. An overview of the CXRF technique will be provided along with a discussion of how CXRF data relates to data collected using SEM-EDS, FTIR, Raman, conventional XRF, x-radiography, IRR, and dendrochronology.
Combinatorial Approach to Materials Fabrication from Higher Hierarchies of Rosette Nanotubes
Authors: Tikhomirov Grigory , Fenniri Hicham 
Published: April 2011

ABSTRACTThe self-assembly of six self-complimentary Guanine – Cytosine hybrid heterocycles bearing hydrophobic substituents has been studied using combinatorial approach in eight solvents under different conditions. The parameters that were varied include: the structure of the self-assembling module, its concentration, the solvent, temperature, and time of self-assembly. scanning electron microscopy (SEM) was used as a screening tool. A wide variety of interesting morphologies was found. The most interesting structures were studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray powder diffraction (XRD).
Damping Characteristics of Commensurate Double-Walled Carbon Nanotube Oscillators
Authors: Ooi Y. , Shintani K. 
Published: April 2011

ABSTRACTThe intertube oscillations of double-walled carbon nanotubes (DWNTs) are investigated using molecular-dynamics (MD) simulation. The inner and outer tubes of model DWNTs have chiral indices of armchair type. The intertube oscillations are damped owing to energy dissipation. The logarithmic decrements and frequencies of the damped oscillations are calculated. The results show that the logarithmic decrement increases with increasing the tube diameter and decreases with increasing the tube length.
Investigating the Growth Process of Vertically Aligned Single-Walled Carbon Nanotubes Synthesized from Alcohol
Authors: Einarsson Erik , Xiang Rong , Ogura Kazuaki , Okawa Jun , Zhang Zhengyi , Maruyama Shigeo 
Published: April 2011

ABSTRACTWe have performed a systematic investigation of the influence of the growth parameters on the synthesis of vertically aligned single-walled carbon nanotubes (VA-SWNTs) by the alcohol catalytic chemical vapor deposition (ACCVD) method. The growth process of the VA-SWNTs was monitored using an in situ optical absorbance technique and the effects of CVD temperature and ethanol pressure on the initial growth rate and the catalyst lifetime were investigated. We found that for a given CVD temperature, there is an optimum pressure at which the VA-SWNT film height is maximized, and this pressure increases with temperature. Below this optimum pressure the growth reaction is first-order, with the arrival of ethanol to the catalyst being the rate-limiting step. The activation energy of the growth was also determined to be approximately 1.5 eV.The root-growth mechanism of VA-SWNTs by the alcohol CVD method was also confirmed by a two-stage growth process. Following a short growth period using normal ethanol, isotope labeled 13C ethanol was introduced to continue the growth. The location of the 13C was confirmed by resonance Raman spectroscopy, confirming the root-growth mechanism.
High-Yield Synthesis of Vertically Aligned Single-Walled Carbon Nanotubes in Ion-Damage and Radical-Damage Free Atmospheric Pressure PECVD
Authors: Nozaki Tomohiro , Ohnishi Kuma , Okazaki Ken 
Published: April 2011

ABSTRACTPlasma-enhanced chemical vapor deposition (PECVD) is recognized as one of the viable fabrication techniques of carbon nanotubes (CNTs). However, “CNTs” synthesized in low-pressure PECVD is overwhelmingly carbon nanofibers or multi-walled carbon nanotubes because catalyst and CNTs receive severe damage from ion bombardment: single-walled carbon nanotubes (SWCNTs) has been exclusively synthesized in the thermal CVD regime except few examples. We present atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) for high-purity vertically-aligned SWCNT synthesis, because both ion-damage and radical-damage are preferentially avoided in atmospheric pressure. Tentative reaction mechanism is also discussed based gas phase chemistry analyzed by quadrupole mass spectrometer.
Vertically Aligned Carbon Nanotube Arrays for Room Temperature Gas Sensors
Authors: Rajaputra Suresh , Mangu Raghu , Ma Ning , Clore Patricia , Qian Dali , Andrews Rodney , Phok Sovannary , Lumpp Janet , Singh Vijay 
Published: April 2011

ABSTRACTVertically aligned multiwalled carbon nanotube (CNT) arrays were fabricated in anodized aluminum oxide (AAO) templates without the use of a catalyst, using xylene pyrolysis. The CNT arrays in AAO template were integrated into a resistive sensor design. The sensors were found to be highly responsive to NH3 and NO2 with steady state sensitivities of 5% and 10% for 100ppm of NH3 and NO2 respectively, at room temperature. Results were interpreted in terms of the CNTs acting as p-type semiconductors. A study was undertaken to elucidate the dependence of sensitivity on the thickness of the conducting amorphous carbon layers on top and bottom. Recovery of the MWNT gas sensor was studied for different types of desorption techniques. The thickness of the amorphous carbon layer (sheet resistance) was found to be critical in determining the sensor response.
Epitaxial and Non-Epitaxial Heterogeneous Integration Technologies at NGST
Authors: Gutierrez-Aitken Augusto , Chang-Chien Patty , Oyama Bert , Tornquist Kelly , Thai Khanh , Scott Dennis , Sandhu Rajinder , Zhou Joe , Nam Peter , Phan Wen 
Published: April 2011

ABSTRACTTo meet increasingly challenging and complex systems requirements, it is not enough to use one single semiconductor technology but to integrate several high performance technologies in an efficient and cost effective way. Heterogeneous integration (HI) approaches lead to a significant higher design flexibility and performance. In this paper we present some of the HI approaches that are being used and developed at Northrop Grumman Space Technology (NGST) that include selective epitaxial growth, metamorphic growth and wafer level packaging (WLP) technology. More recently we are developing a scaled and selective wafer packaging technique to integrate III-V semiconductors with silicon under the COSMOS DARPA program.
Integrated Optics Utilizing GaN-Based Layers on Silicon Substrates
Authors: Rosenberg Armand , Mastro Michael A. , Caldwell Joshua D. , Holm Ronald T. , Henry Richard L. , Eddy Charles R. , Bussmann Konrad , Kim Mijin 
Published: April 2011

ABSTRACTIt is now apparent that future generations of fast electronics and compact sensors may need to rely increasingly on integrated optical components. But integration of electronics and photonics in today's IC's is challenging. Silicon, the ubiquitous electronic material, is neither ideally suited for most photonic functions nor readily integrated with most of the common photonic materials, such as GaAs. The approach we describe here relies on GaN-based films, which can be grown directly on silicon substrates and hence can be potentially integrated with state-of-the-art Si-based electronics. We have demonstrated the fabrication of GaN structures on silicon wafers ranging in overall size from sub-micron to several millimeters, all containing highly accurate individual features on the nm scale. As proof of concept, we have fabricated GaN optical waveguides and photonic crystals containing optical cavities by patterning GaN membranes grown directly on Si wafers. Our optical cavities were designed to have resonant modes within the spectral region of the broad defect-induced luminescence of GaN. We have measured sharp resonant features associated with these cavities by optically pumping above the GaN band edge, and have compared the data to numerical simulations of the spectra. Our results to date demonstrate the feasibility of fabricating high-quality GaN photonic structures directly on Si wafers, thereby providing a possible path to achieving true integration of electronics and photonics in future generations of IC's.
Electron Traps in n-GaN Grown on Si (111) Substrates by MOVPE
Authors: Ito Tsuneo , Terada Yutaka , Egawa Takashi 
Published: April 2011

ABSTRACTDeep level electron traps in n-GaN grown by metal organic vapor phase epitaxy (MOVPE) on Si (111) substrate were studied by means of deep level transient spectroscopy (DLTS). The growth of n-GaN on different pair number of AlN/GaN superlattice buffer layers (SLS) system and on c-face sapphire substrate are compared. Three deep electron traps labeled E4 (0.7-0.8 eV), E5 (1.0-1.1 eV), were observed in n-GaN on Si substrate. And the concentrations of these traps observed for n-GaN on Si are very different from that on sapphire substrate. E4 is the dominant of these levels for n-GaN on Si substrate, and it behaves like point-defect due to based on the analysis by electron capture kinetics, in spite of having high dislocation density of the order of 1010 cm−3.
Effect of Top Dielectric Morphology and Gate Material on the Performance of Nitride-based FLASH Memory Cells
Authors: Cacciato Antonio , Breuil Laurent , Van den bosch Geert , Richard Olivier , Rothschild Aude , Furnémont Arnaud , Bender Hugo , Kittl Jorge A. , Van Houdt Jan 
Published: April 2011

AbstractThe nitride-based SONOS cell, for its excellent scalability and process simplicity, is the candidate to push the scaling roadmap for FLASH memories beyond the limit imposed on floating-gate memories by the electrostatic interference between adjacent cells. The traditional SONOS cell consists of a nitride layer (the storage element) encapsulated by two SiO2 layers which isolate the nitride layer from the Si substrate and the poly-Si gate (Poly-Si/SiO2/Si3N4/SiO2/c-Si). However, the thick tunnel oxide necessary to meet the retention requirements imposes a severe limit on the erase performance because of the erase saturation phenomenon. One possibility to guarantee both the erase and the retention performance is the replacement of the top SiO2 layer with materials of higher dielectric constant (high-k dielectric). The presence of a high-k dielectric reduces the electric field across the top dielectric, thus decreasing the unwanted parasitic electron injection from the gate during the erase operation. This will allow the cell to erase deep so to meet a basic requirement for Gigabit multilevel NAND memories. The introduction of high-k materials in the SONOS stack is unfortunately not straightforward. One problem is the Fermi-level pinning at the poly-Si/high-k interface. Another problem is the morphological changes the high-k material undergoes during the device fabrication thermal budget. These changes can modify the k-value and affect the band offset between gate and high-k material. The results may, in both cases, be the decrease of the barrier for electron injection from the gate and, as a consequence, the deterioration of the erase performance. In this paper we study the effect of gate material and of the morphological transformation associated with the high-k post deposition anneal on the erase and the retention behaviour of nitride-based cells. Two different high-k dielectrics are investigated: Al2O3 (which has already been found to be able to significantly improve the erase operation, guaranteeing at the same time excellent endurance and sufficient bake retention) and HfAlO. We show that both for Al2O3 and HfAlO a trade-off exists between erase and retention, higher PDA temperatures being beneficial for erase but detrimental for retention. We also discuss the effect of Fermi level pinning and poly-Si depletion on the erase behaviour and compare the erase performances of several PVD- and AVD-deposited metal gates.
Current Conduction Mechanism for Low-molecular Organic Nonvolatile Memory
Authors: Seo Sungho , Nam Woo-sik , Lee Gon-sub , Park Jea-gun 
Published: April 2011

AbstractOrganic devices fabricated with a top metal layer/conductive organic layer/middle metal layer/conductive organic layer/bottom metal layer structure have been reported to demonstrate nonvolatile memory behavior such as an after writing (Ion)/after erasing (Ioff) performance of > 1 × 101 and a response time of ∼10 ns, when the organic conductive layers were AIDCN (2-amino-4, 5-imidazoledicarbonitrile), Alq3 (Aluminum tris(8-hydroxyquinoline)), or α-NPD. We fabricated an organic nonvolatile memory device with a structure of α-NPD/Al nanocrystals surrounded by Al2O3/α-NPD/Al, where α-NPD was N,N'-bis(1-naphthyl)-1,1'biphenyl4-4''diamine. A layer of Al nanocrystals, confirmed by a 1.25-MV high voltage transmission-electron-microscope, was uniformly produced between the α-NPD layers by Al layer evaporation at 1.0 Å/sec on the α-NPD followed by O2 plasma oxidation. We confirmed a conduction bistability of ∼102 and a threshold voltage for a set state of 3 V. Al nanocrystals surrounded by amorphous Al2O3 were formed in the α-NPD. They presented seven different reversible current paths for an electron charge or discharge on the nanocrystals. The current slightly increased with an applied bias from 0 V to Vth (a high resistance state (Ioff)), abruptly increased with an applied bias from Vth to Vp, decreased with an increasing applied bias from Vp to Ve (a negative differential resistance (NDR) region), and slightly increased with an applied bias above Ve. After sweeping the first applied voltage from 0 to 10 V (erase), a second applied bias was swept from 0 to Vp (program), where the current followed a high resistance state (Ioff). Next, a third applied bias was swept from 0 to Vp again, where the current followed a low resistance state (Ion). Surprisingly, the ratio of Ion to Ioff was ∼1×102, which is enough current difference to be nonvolatile memory behavior. These I-V characteristics under a positive applied bias were symmetrically repeated under a negative applied bias. All the current sweeping paths were reproducible and symmetrical for an applied bias polarity. In particular, our device demonstrated multi-level nonvolatile memory behavior. It also revealed the current conduction mechanism for each of its operation regions. We observed that the high resistance and low resistance regions followed space-charge-limited current conduction, the Vth to Vp and VNDR to Ve regions followed precisely thermionic-field-emission current conduction, and the above Ve regions followed space-charge-limited current conduction.
Process Optimization of Ni Nanocrystals Formation Using O2 Plasma Oxidation to Fabricate Low-molecular Organic Nonvolatile Memory
Authors: Nam Woo Sik , Lee Gon-Sub , Seo Sung Ho , Park Jea Gun 
Published: April 2011

AbstractWe fabricated organic nonvolatile memory with a device structure of Al/Alq3 (aluminum tris (8-hydroxyquinoline))/Ni nanocrystals surrounded by NiO/Alq3/Al. We obtained the best bistable switching characteristics at a 30-nm Alq3 thickness, 0.1-Å/sec evaporation rate, and 10-nm Ni nanocrystal layer thickness. The electrical behavior of the bistable switching devices was obtained by sweeping the voltage from 0 to 10 V. Our devices showed excellent bistable memory characteristics, such as a Vth of 2 V, Vp of 3 V, Ve of 5 V, and Ion/Ioff ratio of greater than 104. We found that a region of negative differential resistance exists between Vp and Ve.
Molecular Electronics with Large-area Molecular Junctions
Authors: Akkerman Hylke B. , Kronemeijer Auke J. , Blom Paul W. M. , van Hal Paul , de Leeuw Dago M. , de Boer Bert 
Published: April 2011

AbstractA technology is demonstrated to fabricate reliable metal-molecule-metal junctions with unprecedented device diameters up to 100 μm. The yield of these molecular junctions is close to unity. Preliminary stability investigations have shown a shelf life of years and no deterioration upon cycling. Key ingredients are the use of a conducting polymer layer (PEDOT:PSS) sandwiched between a bottom electrode with a self-assembled monolayer (SAM) and the top electrode to prevent electrical shorts, and processing in lithographically defined vertical interconnects (vias) to prevent both parasitic currents and interaction between the environment and the SAM [1].Modeling the current–voltage (I–V) characteristics of alkanedithiols with the Simmons model showed that the low dielectric constant of the molecules in the junction results in a strong image potential that should be included in the tunneling model. Including image force effects, the tunneling model consistently describes the current-voltage characteristics of the molecular junctions up to 1 V bias for different molecule lengths [2].Furthermore, we demonstrate a dependence of the I–V characteristics on the monolayer quality. A too low concentration of long alkanedithiols leads to the formation of looped molecules, resulting in a 50-fold increase of the current through the SAM. To obtain an almost full standing-up phase of 1,14-tetradecanedithiol (C14) a 30 mM concentration is required, whereas a 0.3 mM concentration leads to a highly looped monolayer. The conduction through the full standing-up phase of C14 and C16 is in accordance with the exponential dependence on molecular length as obtained from shorter alkanedithiols [3].Finally, a fully functional solid-state molecular electronic switch is manufactured by conventional processing techniques. The molecular switch is based on a monolayer of photochromic diarylethene molecular switches. The monolayer reversibly switches the conductance by more than one order of magnitude between the two conductance states via optical addressing. This reversible conductance switch operates as an electronic ON/OFF switch (or a reprogrammable data storage unit) that can be optically written and electronically read [4].
Studies of Charge Transport Properties in P3HT/ZnO Composites Using Photoinduced Charge Extraction by Linearly Increasing Voltage Technique
Authors: Chellappan Vijila , Zhu Furong , Liu Minghui , Loh Kian Ping 
Published: April 2011

AbstractThe charge transport properties in a mixture of regio-regular (poly 3-hexylthiophene) (RR-P3HT) and Zinc Oxide nano particle (ZnO) have been studied using the photoinduced charge extraction by linearly increasing voltage (PhotoCELIV) technique. We have studied the effect of ZnO nanoparticle size (12 nm and 50 nm) on the charge transport properties by fixing the composition ratio of P3HT/ZnO hybrid. The PhotoCELIV mobility in P3HT/50nm-ZnO at room temperature is found to be 7.8×10−5cm2/Vs at an applied electric field of 2.5 × 104 V/cm, which increases to 1.7×10−4cm2/Vs for P3HT/12nm-ZnO composite. The temperature and electric field dependence of charge mobility in these composites have been studied and analysed using Gaussian disorder formalism. The obtained results suggest that the charge transport properties in P3HT/ZnO composite, at low ZnO concentrations, can be tuned by varying the size of the nanoparticle.
Transistor Performance and Film Structure of Hexabenzocoronene Derivatives
Authors: Mori Tomohiko , Kikuzawa Yoshihiro , Umemoto Kazuhiko , Nozaki Hiroshi , Seno Yoshiki , Takeuchi Hisato 
Published: April 2011

AbstractHexabenzocoronene (HBC) derivatives that are designed to self-assemble into lamellar aggregates were synthesized. The derivatives were deposited as an active layer in an organic field-effect transistor (OFET) using vacuum sublimation. The dihexyl and tetrahexyl derivatives (2H-HBC, 4H-HBC) increased the field-effect mobilities and on/off ratios by a factor of 10 or more compared to unsubstituted HBC and hexahexyl-hexabenzocoronene (6H-HBC). The crystal and thin film structures were determined by powder x-ray diffraction and grazing incidence X-ray diffraction (GIXD). The data indicate that 2H-HBC and 4H-HBC self-assemble into lamellar aggregates. 2H-HBC forms layers of aromatic cores that are sandwiched by the layers of hexyl groups, which is a preferable crystal structure for carrier transport. The good OFET performance could be explained by the self-assembly in lamellar aggregates of 2H-HBC and 4H-HBC, in contrast to self-assembly in the columnar aggregate of 6H-HBC and the low self-assembling properties of unsubstituted HBC.