bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Metal Nitride Compounds: Can they be Synthesized at High-Pressures?
Authors: Kroll Peter 
Published: April 2011

AbstractWe apply our procedure of including nitrogen fugacity into thermochemical calculations to compute phase diagrams in the rhenium-nitrogen and ruthenium-nitrogen systems. The combination of first-principle and thermochemical calculations let us predict the sequential nitridation of Re at high-pressure/high-temperature conditions. At 3000 K, Re will react with nitrogen at about 32 GPa yielding ReN. Formation of ReN2 with CoSb2-type structure is predicted for pressures exceeding 50 GPa at this temperature. The recently proposed marcasite-type RuN2 will be attainable at 3000 K at pressures above 30 GPa from a mixture of Ru and RuN2.
Materials and Techniques of Thai Painting
Authors: Eremin Katherine , Stenger Jens , Khandekar Narayan , Huang Jo Fan , Betley Theodore , Aspuru-Guzik Alan , Vogt Leslie , Kassal Ivan , Speakman Scott 
Published: April 2011

AbstractThe materials and techniques employed in 18th to 20th century art works from Thailand have received little attention compared to those of other Asian countries, most notably China and Japan. A multi-disciplinary study of Thai manuscripts and banner paintings aims to characterize the materials used, inorganic and organic pigments and binders, and the painting techniques employed. Samples from these works have been analyzed by a range of techniques, including x-ray flourescence (XRF), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive microanalysis (SEM-EDS). The results suggest a change in palette from the 18th to 20th century due to the introduction of imported pigments, most notably emerald green, Prussian blue and chrome yellow, during the 19th and early 20th century. The analyses show that the green pigment used on most 18th century manuscripts is an organic copper salt, a hydrated copper citrate, which has not previously been identified on art works. The occurrence of this on a number of different art works suggests deliberate manufacture of this unusual pigment. The color of the copper citrates differs depending on their hydration state and they are easily dehydrated and re-hydrated. This suggests some alteration of the original manuscript pigments might be expected, raising questions as to the original color of the pigment and whether the visual appearance has altered with time. In order to assess this, the pigments found on the art works must be fully characterized and any variations identified. The study includes laboratory based sythesis with pure reagents and synthesis following a recipe for refinement of verdigris given in a 17th century Venetian manuscript.
Molecular Dynamics Study of Electron Irradiation Damages in Carbon Nanomaterials
Authors: Yasuda Masaaki , Majima Takashi , Kimoto Yoshihisa , Tada Kazuhiro , Kawata Hiroaki , Hirai Yoshihiko 
Published: April 2011

ABSTRACTMolecular dynamics (MD) studies are carried out to investigate the electron irradiation damages in carbon nanomaterials. The interaction between an incident electron and a carbon atom is modeled based on the Monte Carlo method using the elastic scattering cross section. The electron irradiation damages in graphen, graphite, single-walled carbon nanotube (SWNT) and carbon nanopeapod are demonstrated. The cross-links among the nanostructures caused by the knock-on effect are observed as typical damages. The dependence of the damages on the electron primary energy is also shown for the SWNT.
Stabilization Mechanisms in Multiwalled Peapods
Authors: Scipioni Roberto , Oshiyama Atsushi , Ohno Takahisa 
Published: April 2011

ABSTRACTWe discuss the energetics of Double walled Carbon nanotubes (DWCNT) peapods as compared to their single walled (SWNCNT) counterparts. We show that filling DWCNT with C60 fullerenes is energetically more favourable than SWNTs. Essentially two mechanisms are responsible for this phenomenon: 1] the interalyer state between the tubes which acts as repository of charge, 2] The Van der Waals interactions with the outer tubes. We discuss in some details the first effect using pseudopotential DFT, LDA first principles simulations for the two peapods C60@(15,0) and C60@(15,0)-(24,0)
Carbon Cones - a Structure with Unique Properties
Authors: Helgesen Geir , Knudsen Kenneth D. , Pinheiro Jean Patrick , Skjeltorp Arne T. , Svåsand Eldrid , Heiberg-Andersen Henning , Elgsaeter Arnljot , Garberg Torgunn , Naess Stine Nalum , Raaen Steinar , Tverdal Merete F. , Yu Xiaofeng , Melø Thor Bernt 
Published: April 2011

ABSTRACTLarge-scale production of perfect conical carbon nanostructures that are fundamentally different from the other nanocarbon materials, such as buckyballs and nanotubes, can be made using the so-called Kvaerner Carbon Black & Hydrogen Process. This involves pyrolysis of hydrocarbons using a torch plasma process. The carbon cones that occur appear in five distinctly different forms. In addition, disk-shaped particles may be produced. Here we report about the current status for the experimental research and theoretical modeling of these particles, which have properties different from the other known forms of carbon.
Fabrication of Closed packed Single-walled Carbon Nanotube film with nanometer thickness
Authors: Matsui Jun , Yamamoto Kohei , Miyashita Tokuji 
Published: April 2011

ABSTRACTClosed packed film of single-walled carbon nanotubes (SWCNTs) with nanometer thickness was fabricated using a liquid-liquid interface. SWCNT was solubilized into water using sodium dodecyl sulfate as a surfactant. The SWCNTs in SDS-water suspension were used as a water phase and n-hexane was added to the suspension to form a liquid-liquid interface. After addition of ethanol to the mix solution, SWCNTs were assembled at the interface. The film form at the interface was transferred onto a silicon substrate. The AFM image of the transferred film shows a closed packed SWCNT film with a few nanometers thicknesses.
Investigation of Blistering Phenomena in Hydrogen-Implanted GaN and AlN for Thin Film Layer Transfer Applications
Authors: Singh Rajendra , Scholz R. , Christiansen S. H. , Goesele U. 
Published: April 2011

ABSTRACTHigh dose hydrogen implantation-induced blistering phenomena in GaN and AlN have been investigated for potential thin film layer transfer applications. GaN and AlN were implanted with 100 keV H2+ ions with various ion doses in the range of 5´1016 to 2.5´1017 cm−2. After implantation the samples were annealed at higher temperatures up to 800°C in order to observe the formation of surface blisters. In the case of GaN only those samples that were implanted with a dose of 1.3´1017 cm−2 or higher showed surface blistering after post-implantation annealing. For AlN the samples those were implanted with a dose of 1.0´1017 or 1.5´1017 cm−2 displayed surface blistering after post-implantation annealing. Cross-sectional transmission electron microscopy was utilized to observe the microscopic defects that eventually cause surface blistering. Large area microcracks, as revealed in the XTEM images, were clearly observed in the case of both GaN and AlN after post-implantation annealing. A comparison of the hydrogen implantation-induced blistering in GaN and AlN has also been presented.
Growth and Characterization of InSb films on Si (001)
Authors: Tran Lien , Dobbert Julia , Hatami Fariba , Masselink W. Ted 
Published: April 2011

ABSTRACTThe replacement of native oxides with deposited oxides in CMOS technology opens the door to replacing the Si with semiconductors without high-quality native oxides. For example, the use of InSb in logic applications could allow much lower operating voltages and power dissipation due to the InSb channels reaching saturation at significantly lower electric fields. Epitaxy of InSb onto Si could be done directly or using an intermediate layer such as GaP, GaAs, or InP. In the current work we describe the growth of InSb on Si (001) and discuss the structural and electrical properties of the resulting InSb films. The samples were characterized in terms of background electron concentration, mobility, deep level traps, Hall sensitivity, and x-ray rocking curve width.Samples were grown using molecular-beam epitaxy in a Riber-Compact 21T system. Antimony was supplied with a Veeco valved cracker cell. Vicinal Si(001) substrates offcut by 4º toward [110] were prepared by repeated oxidation and oxide-removal and then loaded into the MBE system. After the substrate temperature had been increased to about 820ºC, the surface shows a clear 2&#61620;4 reconstruction and appears to be free of oxide. This reconstruction remains until the substrate temperature reaches 1015ºC, at which temperature a 2&#61620;1 appears, indicating a dominance of double-height steps. After allowing the substrate to cool to the intended growth temperature for InSb, it is exposed to cracked Sb, resulting in the surface going from 2&#61620;1 to 1&#61620;1. This 1&#61620;1 reconstruction remains throughout the subsequent InSb deposition. InSb was deposited with a Sb/In flux ratio of about 5 and a growth rate of 0.2 nm/s. We have investigated growth temperatures between 300 and 420ºC for growth. To prevent the formation of the defects we introduced in some samples GaSb/AlSb supperlattice buffer layer. The best structural quality has been achieved at a growth temperature of 420ºC using GaSb/AlSb supperlattice buffer layer, resulting in our best electron mobility of 2.6&#61620;104 cm2/Vs for a 2&#61549;m film at room temperature. The samples grown at 420°C have the narrowest x-ray rocking curve width (FWHM of about 950 arcsec). Deep level noise spectra indicate the existence of the deep levels. The sample with the best crystal quality and highest mobility has the lowest traps. The deep levels have a temperature dependent behavior.
GaN Electrochemical Probes and MEMS on Si
Authors: Heinle Ulrich , Benkart Peter , Daumiller Ingo , Kunze Mike , Sönmez Ertugrul 
Published: April 2011

ABSTRACTAlGaN /GaN HEMT structures were used for liquid and gas sensors. The sensitivity of pH sensors was determined after clean-in-place tests. A multigas measurement at 330°C is presented. A piezo-driven mechanical actor is demonstrated and used as a variable capacitor. GaN on silicon logic circuitry is demonstrated at 250°C.
High Optical Quality GaN Nanopillars Grown on (111) Si Using Molecular Beam Epitaxy
Authors: Vajpeyi Agam Prakash , Tsiakatouras G. , Adikimenakis A , Tsagaraki K. , Androulidaki M , Georgakilas Alexandros 
Published: April 2011

ABSTRACTThe spontaneous growth of GaN nanopillars on (111) Si by plasma assisted molecular beam epitaxy has been investigated. The growth of GaN nanopillars on Si is driven by the lattice mismatch strain energy on Si and the high surface energy of the nitrogen stabilized (0001) GaN surface. A higher growth rate of nanopillars compared to a compact GaN film suggests the diffusion of Ga atoms from the uncovered substrate areas to the nucleated GaN nanopillars. The GaN nanopillars were characterized by field-emission scanning electron microscopy (FE-SEM), photoluminescence, and micro Raman spectroscopy. SEM image revealed that average diameter of GaN nanopillars was in the range of 70-100nm and an average height of 600nm. The photoluminescence (PL) spectra indicate the good emission property of the nanopillars. The low temperate PL spectrum exhibited an emission peak at 3.428eV besides a sharp excitonic peak. PL and Raman spectra indicate that GaN nanopillars are fully relaxed from lattice and thermal strain.
Nondestructive defect measurement and surface analysis of 3C-SiC on Si (001) by electron channeling contrast imaging
Authors: Picard Yoosuf N. , Locke Christopher , Frewin Christopher L. , Myers-Ward Rachael L. , Caldwell Joshua D. , Hobart Karl D. , Twigg Mark E. , Saddow Stephen E. 
Published: April 2011

ABSTRACTThe electron channeling contrast imaging (ECCI) technique was utilized to investigate atomic step morphologies and dislocation densities in 3C-SiC films grown by chemical vapor deposition (CVD) on Si (001) substrates. ECCI in this study was performed inside a commercial scanning electron microscope using an electron backscatter diffraction (EBSD) system equipped with forescatter diode detectors. This approach allowed simultaneous imaging of atomic steps, verified by atomic force microscopy, and dislocations at the film surface. EBSD analysis verified the orientation and monocrystalline quality of the 3C-SiC films. Dislocation densities in 3C-SiC films were measured locally using ECCI, with qualitative verification by x-ray diffraction. Differences in the dislocation density across a 50 mm diameter 3C-SiC film could be attributed to subtle variations during the carbonization process across the substrate surface.
Fabrication and Characterization of Ferroelectric Polymer/TiO2/Al-doped ZnO Structures
Authors: Aizawa Koji 
Published: April 2011

AbstractCharacterization of 700-nm-thick poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)]/TiO2/Al-doped ZnO (AZO) structures on a glass substrate were investigated. In this study, the sputtered TiO2 films as insulator were used for the reduction of leakage current. The leakage current density of the fabricated Pt/P(VDF/TrFE)/AZO and Pt/P(VDF/TrFE)/170-nm-thick TiO2/AZO structures were approximately 8.7 and 3.9 nA/cm2 at the applied voltage of 10 V, respectively. In the polarization vs. voltage characteristics, the fabricated Pt/P(VDF/TrFE)/TiO2/AZO structures showed hysteresis loops caused by ferroelectric polarization. The remnant polarization (2Pr) and coercive voltage (2Vc) measured from a saturated hysteresis loop at the frequency of 50 Hz were approximately 12 μC/cm2 and 105 V, respectively. These results suggest that the insertion of TiO2 film is available for reducing the gate leakage current without changing the ferroelectric properties.
Organic Field Effect Transistor using BaTiO3-Mn Doped and P(VDF-TrFE) for Non Volatile Memory Application
Authors: Pattnaik Sambit , Garg Ashish , Katiyar Monica 
Published: April 2011

AbstractHere, we report fabrication of an organic field effect transistor that can be used as a memory device. We have evaluated inorganic ferroelectric insulator manganese doped barium titanate(BTO), organic poly(vinylidene fluoride trifluoroethylene) P(VDF-TrFE), and their composite. The inorganic and organic ferroelectrics were fabricated using low cost process of spin coating followed by annealing to enhance crystallinity. The ferroelectric phase evolution is assessed by X-ray diffraction, MIM structure is used to study polarization behaviour and leakage current. Finally, OFETs are fabricated using thermal evaporation of 75 nm of pentacene. Gold electrodes of 70 nm were evaporated for the top contact devices keeping W/L=40. The OFET devices, for BTO/P(VDF-TrFE) composite insulator, showed memory effect with shift in threshold voltage of 8.5 ± 1.5V.
Resistive Electrical Switching of Cu+ and Ag+ based Metal-Organic Charge Transfer Complexes
Authors: Mueller Robert , Billen Joris , Katzenmeyer Aaron , Goux Ludovic , Wouters Dirk J. , Genoe Jan , Heremans Paul 
Published: April 2011

AbstractMemory cells based on Cu+ and Ag+ metal-organic charge-transfer complexes, as for example CuTCNQ (where TCNQ denotes 7,7',8,8'-tetracyanoquinodimethane), are well known for their bistable resistive electrical switching since 1979. The switching mechanism however remained unclear for very long time. In this contribution we describe the different views (bulk vs. interfacial switching), give evidence for interfacial switching in the case of CuTCNQ, and present a model allowing explaining the bipolar resistive electrical switching by an interfacial effect, even for experiments considered until now as proof for bulk switching. The proposed switching mechanism is based on bridging of an ion-permeable layer (or gap) by conductive Cu channels, which are formed and dissolved by an electrochemical reaction implying monovalent Cu+ cations, originating from a solid ionic conductor (as for example CuTCNQ). The model was furthermore generalized to other memory systems consisting of a permeable layer and a solid ionic conductor, including also inorganic solid ionic conductors as for example Ag2S.
Reversible Electrical Resistance Switching in GeSbTe Thin Films: An Electrolytic Approach without Amorphous-Crystalline Phase-Change
Authors: Pandian Ramanathaswamy , Kooi Bart J. , Palasantzas George , De Hosson Jeff Th. M. 
Published: April 2011

AbstractBesides the well-known resistance switching originating from the amorphous-crystalline phase-change in GeSbTe thin films, we demonstrate another switching mechanism named ‘polarity-dependent resistance (PDR) switching’. The electrical resistance of the film switches between a low- and high-state when the polarity of the applied electric field is reversed. This switching is not connected to the phase-change, as it only occurs in the crystalline phase of the film, but connected to the solid-state electrolytic behavior i.e. high ionic conductivity of (Sb-rich) GeSbTe under an electric field. I-V characteristics of nonoptimized capacitor-like prototype cells of various dimensions clearly exhibited the switching behavior when sweeping the voltage between +1 V and -1 V (starting point: 0 V). The switching was demonstrated also with voltage pulses of amplitudes down to 1 V and pulse widths down to 1 microsecond for several hundred of cycles with resistance contrasts up to 150 % between the resistance states. Conductive atomic force microscopy (CAFM) was used to examine PDR switching at nanoscales in tip-written crystalline marks, where the switching occurred for less than 1.5 V with more than three orders of resistance contrasts. Our experiments demonstrated a novel and technologically important switching mechanism, which consumes less power than the usual phase-change switching and provide opportunity to bring together the two resistance switching types (phase-change and PDR) in a single system to extend the applicability of GeSbTe materials.
Current Conduction Mechanism for Non-volatile Memory Fabricated with Conductive Polymer Embedded Au Nanocrystals
Authors: Lee Jong Dae , Seung Hyun Min , Han Byeong Il , Lee Gon-Sub , Park Jea-gun 
Published: April 2011

AbstractMany researchers have investigated organic nonvolatile memory devices as one of candidates device for next generation nonvolatile memory because of their low-cost, flexible and simple fabrication. The memory phenomenon in these devices is based on the electrical bistability of the material, which has two resistance states. We report memory effect in organic molecules based on electrical bistability of the materials and the bistable phenomenon was observed in poly(N-vinylcarbazole) (PVK) layer, containing a high density of Au nanocrystals and sandwiched between Al electrodes. The device was fabricated on cleaned SiO2. First, Al for the bottom electrode was deposited on SiO2 substrate by thermal evaporation in a vacuum chamber (pressure ∼10−6 torr). The PVK was dissolved with chloroform, spin-coated on the Al electrode, and baked at 120¡ÆC for 2 min to evaporate the solvent away. Subsequently, a 5-nm-thick Au film was deposited on the PVK. Additional PVK was then spin-coated on the Au film and baked. Next, the device was cured at 300¡É for 2 h in air to produce the Au nano-crystals. This device showed good nonvolatile memory characteristics. It was confirmed that it shows several region of current levels, (ION, IOFF, IINTER). When the voltage increased from zero in the OFF state (low conductivity state), the current increased rapidly at the threshold voltage (Vth), and presented a regime of negative differential resistance (NDR) after writing. Moreover ON and OFF states could be set at voltages at Vprogram (or Vp) and Verase (or Ve), respectively, and could be read at 1 V. After the device was programmed by sweeping the voltage from 0 to Vp, the current followed the high conductivity state and stayed in the ON state. And the device was programmed by sweeping the voltage from 0 to Ve, the current followed the low conductivity state and stayed in the OFF state. Furthermore, they exhibited seven different reversible current paths (intermediate states) capable for approving electron charge or discharge on surface of Au nanocrystals by sweeping the voltage from 0 to VNDR. Our results demonstrate that the fundamental parameters of the device were stable; the values of Vth, Vp, and Ve were ∼2.8, ∼4, and ∼8 V, respectively. In particular, this device exhibited excellent nonvolatile memory behavior, with bistability (ION/IOFF) of >1×102 and an intermediate state for multi-bit operation. We suggest that the current conduction mechanism clearly follow space-charge-limited(SCLC) for low conductivity state, thermionic field emission for electron charge(writing) or discharge(erasing), and F-N tunneling after erasing.
Theoretical Research of Loop Formation Process in Conducting Polymers
Authors: Turaeva Nigora , Oksengendler Boris 
Published: April 2011

AbstractConducting polymers promise a wider range of successful devices than traditional semiconductors. Differing from the traditional semiconductors in conducting polymers the topology of the system may be significant. Some of the important features such optic and electric properties can be changed largely by loop formation. In this work the loop formation process in conducting polymers has been considered by means of the Green-function method for the electronic spectra fixing. It was shown that at the changing of connectivity of quasi-one dimensional simple polymer strand due to the loop formation two local electronic states are appeared in the electronic spectra of the system. We supposed such model can be important for optic properties of such polymer systems with loops, increase the reaction ability of local loop area, loop stabilization due to the electron-conformational interaction in conducting polymers.
Surface Polymerization of the Thiophen Molecules in Chemically Adsorbed Monolayer
Authors: Yamamoto Shin-ichi , Ogawa Kazufumi 
Published: April 2011

AbstractUsing the time-averaged dielectrophoretic force from an applied electric field, we have observed the assembly of a chemically adsorbed monomolecularlayer (CAM) into microwires, connections, and an electric path according to the location within field regions of a lithographically patterned array of two platinum (Pt) electrodes. A Pt electrode/monolayer/Pt electrode junction was fabricated by the self-assembly of a rigid monomolecular, namely 3-{6-{11-(Trichlorosilyl) undecanoyl} hexyl} thiophene (TEN) with thiophen groups, in the lateral direction between the Pt gap electrodes. The technique of a conductive probe AFM (CP-AFM) has been used to investigate the forward bias conduction properties of a TEN film grown by a wet process deposition on a glass substrate. The self-assembly depends on: (1) the ideal rigidity of the chemically adsorptive monomolecular layer (CAM) and (2) the strong affinity of the thiophen end groups of the CAM for the Pt electrode. The current–voltage (I–V) characteristics of the conjugated thiophen junction exhibited stepwise features at room temperature. The (I–V) characteristics can be explained as an electron transport through the junction. From the results in the atmosphere, the conductivity of a lateral conjugated polythiophen group was calculated to be 5.0×104 S/cm. Understanding and using these effects will allow the controlled fabrication and the positioning of microwires or connections at densities far above what is now achievable.