bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Promise of Nanocomposite Thermoelectric Materials
Authors: Dresselhaus Mildred , Chen Gang , Ren Zhifeng , McEnaney Kenneth , Dresselhaus G. , Fleurial Jean-Pierre 
Published: August 2010

AbstractThe concept of using nanocomposite thermoelectric materials in bulk form for practical applications is presented. Laboratory studies have shown the possibilities of nanostructures to yield large reductions in the thermal conductivity while at the same time increasing the power factor. Theoretical studies have suggested that structural ordering in nano-systems is not necessary for the enhancement of ZT, leading to the idea of using nanocomposites as a practical scale-up technology for making bulk thermoelectric materials with enhanced ZT values. Specific examples are presented of nanocomposite thermoelectric materials developed by our group based on the familiar silicon germanium system, showing enhanced thermoelectric performance through nano-structuring.
Electronic structure and transport properties of ternary skutterudite: CoX3/2Y3/2
Authors: Volja Dmitri , Fornari Marco , Kozinsky Boris , Marzari Nicola 
Published: August 2010

AbstractElectronic properties of ternary skutterudites AX3/2Y3/2 (A=Co, X=Ge, Sn and Y=S, Te) are investigated using first principles calculations to clarify recent experimental results. Band derivatives are computed accurately within an approach based on Maximally Localized Wannier Functions (MLWFs). Band structures exhibit larger effective masses compared to parental binary CoSb3. Our results also indicate a more parabolic dispersion near the top of the valence band and a multivalley character in both conduction and valence band. Despite the improved thermopower these skutterudites has relatively low power factor due to increased resistivity. The fundamental cause of such large resistivity seems to be associated with the ionicity of the bonding.
Characterization and Fabrication of InGaN-based Blue LED with Underlying AlGaN/GaN SLS Cladding Layer Grown on Si(111) Substrate
Authors: Ahmad Shuhaimi Bin Abu Bakar , Pum Chian Khai , Suzue Takaaki , Nomura Yukiyasu , Egawa Takashi 
Published: August 2010

AbstractThis paper reports improved optical characteristics of InGaN-based light-emitting-diode (LED) grown on Si(111) substrate by the insertion of an Al0.06Ga0.94N/GaN strained-layer-superlattices (SLS) cladding layer after AlN/GaN multilayer (ML) growth, under the multi-quantum-well (MQW) active layer. The insertion of underlying Al0.06Ga0.94N/GaN SLS cladding layer has shown to improve epitaxial layer quality in x-ray diffraction (XRD) analysis, reduce wavelength peak fluctuations in photoluminescence (PL) surface mapping, and improve optical and electrical characteristics of the LED sample. A 34% increase of light intensity at 50 mA current injection and a narrower wavelength peak have been achieved by the insertion of Al0.06Ga0.94N/GaN SLS cladding layer. LED with underlying Al0.06Ga0.94N/GaN also shows superior current-voltage (I-V) characteristics with operation voltage of 3.2 V at 20 mA and series resistance of 16 Ω.
Diffusion Effect between Schottky Metals and AlGaN/GaN Heterostructure during High Temperature Annealing Process
Authors: Choi Young-Hwan , Lim Jiyong , Kim Young-Shil , Han Min-Koo 
Published: August 2010

AbstractWe have investigated the change of the Schottky contact surface and the interface between Schottky metals and AlGaN/GaN heterostructure after the annealing process for 35 min at 300 °C. The secondary ion mass spectroscopy (SIMS) and the scanning electron microscopy (SEM) show that the Schottky metals and AlGaN/GaN heterostructure interacted actively during the annealing process. The atoms in Schottky contact and AlGaN/GaN heterostructure diffused interactively and the surface roughness of Schottky contact was increased. After the annealing process for fabricated AlGaN/GaN High-Electron-Mobility Transistor (HEMT), the threshold voltage was shifted by +0.2 V and the leakage current was decreased by 40 %.
Surface Modification of Tungsten Oxide-Based Photoanodes for Solar-Powered Hydrogen Production
Authors: Gaillard Nicolas , Kaneshiro Jess , Miller Eric L. , Weinhardt Lothar , Bär Marcus , Heske Clemens , Ahn Kwang-Soon , Yan Yanfa , Al-Jassim Mowafak 
Published: August 2010

AbstractWe report on the development of tungsten-oxide-based photoelectrochemical (PEC) water-splitting electrodes using surface modification techniques. The effect of molybdenum incorporation into the WO3 bulk or the surface region of the film is discussed. Our data indicate that Mo incorporation in the entire film (WO3:Mo) results in poor PEC performances, most likely due to defects that trap photo-generated charge carriers. However, compared to a pure WO3 (WO3:Mo)-based PEC electrode, a 20% (100%) increase of the photocurrent density at 1.6 V vs. SCE is observed if the Mo incorporation is limited to the near-surface region of the WO3 film. The resulting WO3:Mo/WO3 bilayer structure is formed by epitaxial growth of the WO3:Mo top layer on the WO3 bottom layer, which allows an optimization of the electronic structure induced by Mo incorporation while maintaining good crystallographic properties.
Effect of Cationic or Anionic Dopants on Optical and Photocatalytic Properties of TiO2 Nanopowders made by Flame Spray Synthesis (FSS)
Authors: Michalow Katarzyna Anna , Heel Andre , Graule Thomas , Rekas Mieczyslaw 
Published: August 2010

AbstractTiO2, TiO2-1at.% W and TiO2-1at.% Cr were produced from metal-organic precursors by flame spray synthesis (FSS). TiO2-0.5at.% N was obtained by ammonolysis of FSS made TiO2 nanopowder in a rotating tube furnace under NH3 atmosphere. According to the X-ray diffraction (XRD) analysis, anatase is the predominant phase in all samples. Diffusive reflectance and the resulting band gap energy (Eg) were determined by diffusive reflection spectroscopy (DRS).
Additional impurity bands at 2.43 and 2.57 eV for N- and Cr-doped TiO2, respectively have been observed. The impurity band formed in the band gap resulted in increase of the light absorption in the visible range. The photocatalytic performance of the nanopowders under ultraviolet (UV, 290-410 nm) and visible light irradiation (Vis, 400-500 nm) was studied by the degradation of methylene blue (MB) in aqueous suspensions. It was found that all types of dopants influence the structure, interaction with the visible light as well as photocatalytic activity. Among all nanopowders, TiO2-W exhibited the best photoactivity, much higher than the commercial TiO2-P25 nanopowder. The optimum of the photodecolourization was obtained for 0.7 and 1 at.% W.
Efficient Carbon Nanotube Field Emitter using Electrospun Carbon Nanofibers as a Flexible Electrode
Authors: Matsumoto Hidetoshi , Suzuki Kenichi , Tsuboi Kazuma , Minagawa Mie , Tanioka Akihiko , Hayashi Yasuhiko , Fukuzono Kazuyuki , Amaratunga Gehan A.J. 
Published: August 2010

AbstractThermal-stable, conductive, and flexible carbon fabric (CF), which is composed of thin carbon fibers prepared by electrospinning, was used for the substrate of carbon nanotube (CNT) field emitter arrays. The field emitter arrays were prepared by chemical vapor deposition (CVD). The current density-electric field characteristics revealed that the CNT field emitter arrays on CF produced a higher current density at a lower turn-on voltage compared to ones on a Si substrate. This emitter integrated with a gate electrode based on hierarchy-structured carbon materials, CNTs on CF, can be used for light sources, displays, and other electronic devices.
Semiconductor-metal Phase Transition in Doped Ion Beam Synthesized VO2 Nanoclusters
Authors: Karl Helmut , Dreher J. , Stritzker B. 
Published: August 2010

AbstractWe have synthesized W and Mo doped VO2 nanoclusters embedded in 200 nm thick thermally grown SiO2 on 4-inch silicon wafers by sequential ion implantation of the elements V, W, Mo and O. The implantation energies have been chosen to locate the mean projected range in the centre of the SiO2 thin film. A post implantation rapid thermal annealing step in flowing Ar at 1000°C for 10 min leads to the growth of doped VO2 nanoclusters. The optical properties of the nanoclusters were analyzed by temperature dependent spectral ellipsometry in the spectral range of 320 to 1700 nm. It will be shown, that the semiconductor-metal phase transition hysteresis width starting at 50K in the undoped case can be systematically closed by increasing dopand concentration.
A Facile Method for Patterning Substrates with Zinc Oxide Nanowires
Authors: Cho Jeong-Hyun , Cha Elizabeth W , Gracias David 
Published: August 2010

AbstractConventional growth of zinc oxide (ZnO) nanowires (NWs) is typically carried out using vapor liquid solid (VLS) and chemical vapor deposition (CVD) methods. While these methods are effective, they often involve the use of specialty gasses and equipment. We have discovered that ZnO NWs grow spontaneously from zinc (Zn) films (thermally evaporated on silicon (Si) substrates) when the films are merely heated on a hot-plate in air at ambient pressures for 10 minutes. This process does not involve any metal catalysts, seed layers, specialty gasses or surface treatments in forming patterned regions (on silicon substrates) of NWs with typical diameters in the range of 20-50 nm and lengths of 2-3 μm.
Polyanion Conduction Mechanism in Solid Scandium Tungstate
Authors: Zhou Yongkai , Adams Stefan , Neiman Arkady 
Published: August 2010

AbstractScandium tungstate is investigated as a model material for solid electrolytes in which polyatomic anions, here WO42–, are mobile in the solid state. Simulations using structures with artificially induced WO42–vacancy, Frenkel defect and Schottky defects produced lower activation energy compared to the initially defect-free model. Simulations with Frenkel defect structures show low activation energy but the interstitial WO42–has initially a strong preference to return to the vacant tungstate site. The vacancy defect model reproduces the activation energy to the experimental conductivity studies more closely. Qualitative considerations support the idea that vacancies formed during the sample preparation are the most abundant mobile defect among the investigated cases. Nonstoichiometric samples with varying initial Sc2O3:WO3ratios Sc2O3- x WO3, where x = 2.9, 3.0 and 3.1, are synthesized and characterized by XRD and impedance measurements, but a significant influence on the conductivity could not be confirmed experimentally.
Enhancing Superconducting Parameters by Array of External Magnetic Dots
Authors: Yeh Wei Jiang , Cheng Bo 
Published: August 2010

AbstractEnhancing the pinning force in high-Tc superconductors can be achieved by externally introduced periodic magnetic dots. We use a novel nano-technique to deposit periodic sub-micon Ni dots on YBa2Cu3O7 thin films. The current versus voltage characteristics of an YBa2Cu3O7 thin film strip with uniform Ni dots are measured at various temperatures and magnetic fields. They are compared with the current versus voltage characteristics of a bare YBa2Cu3O7 thin film strip without magnetic dots. It is found the critical current value of the strip with Ni dots reduces with a much slower pace as the magnetic field strength increases in comparison with the value of the bare sample.
Real-Time Visualization Method of Surface Plasmon Resonance with Spectroscopic Attenuated Total Reflection
Authors: Murai Kensuke 
Published: August 2010

AbstractWe report the real-time visualization method of surface plasmon resonance with the spectroscopic attenuated total reflection. Recently, surface plasmon resonance (SPR) had been studied for plasmonics devices to construct faster processor in the electronic microprocessors. SPR is strong interaction between light and free electron near metal surface, which cause absorption of light due to its resonance. The behavior can be explained with Fresnel’s equation. As the wave number of light with a certain frequency is not matched with that of surface plasmon, a prism or a grating is used in order to compensate this mismatching. In the prism case, the wave number is changed by changing the incident angle to the metal surface inside the prism as ksp=n*k0sinθ, where ksp and k0 is the wave numbers of surface plasmon and incident light, respectively, n is the refractive index of the prism and θ is the incident angle to the metal surface inside the prism. Therefore, the SPR can be observed by absorption of light as functions of the wavelength and the incident angle. This resonance behavior as functions of the wavelength and the incident angle can be observed directly with a two-dimensional detector such as a CCD camera. As the two-dimensional SPR images for 50nm-thick silver films on the prism surface have been observed experimentally, they have good agreement with calculated ones. Kretchmann configuration using a glass prism and an approximately 50-nm-thick silver or gold film was often used in order to evaluate the optical constants of the film. Most of SPR signals had been measured with either angular or spectral dependence with this geometry. In the case of angular dependence, the monochromatic laser, e.g. He-Ne laser at 632.8nm, is often used for the incident light. One can measure reflection loss as a function of an incident angle in the total reflection region. Increase in the resonance angle of SPR is well known when the thin oxide film on the metal film. The two-dimensional image of SPR is called “surface plasmon spectral fingerprint”, because it can inform conditions of metal films whether they are reacted or oxidized. Many fingerprints are expected by changing the thickness of the coating layer on the silver surface. In our method, thin metal film on a prism was excited by focusing beam of white light. SPR was clearly visualized with a spectrometer equipped with a two-dimensional CCD detector in the coordination of the incident angle and the wavelength. Various metal films could be distinguished even in partially oxidized condition. This real-time SPR visualization method would be useful not only for monitoring of surface reaction but for fabricating plasmonic devices.
Electron Microscope Study of Strain in InGaN Quantum Wells in GaN Nanowires
Authors: Geiss Roy , Bertness Kris , Roshko Alexana , Read David 
Published: August 2010

AbstractStrains in GaN nanowires with InGaN quantum wells (QW) were measured from transmission electron microscope (TEM) images. The nanowires, all from a single growth run, are single crystals of the wurtzite structure that grow along the <0001> direction, and are approximately 1000 nm long and 60 nm to 130 nm wide with hexagonal cross-sections. The In concentration in the QWs ranges from 12 to 15 at %, as determined by energy dispersive spectroscopy in both the transmission and scanning electron microscopes. Fourier transform (FT) analyses of <0002> and <1100> lattice images of the QW region show a 4 to 10 % increase of the c-axis lattice spacing, across the full specimen width, and essentially no change in the a-axis value. The magnitude of the changes in the c-axis lattice spacing far exceeds values that would be expected by using a linear Vegard's law for GaN – InN with the measured In concentration. Therefore the increases are considered to represent tensile strains in the <0001> direction. Visual representations of the location and extent of the strained regions were produced by constructing inverse FT (IFT) images from selected regions in the FT covering the range of c-axis lattice parameters in and near the QW. The present strain values for InGaN QW in nanowires are larger than any found in the literature to date for other forms of InxGa1-xN (QW)/GaN.
Backside Analysis of Ultra-Thin Film Stacks in Microelectronics Technology Using X-ray Photoelectron Spectroscopy
Authors: Hantschel Thomas , Demeulemeester Cindy , Suderie Arnaud , Lacave Thomas , Conard Thierry , Vandervorst Wilfried 
Published: August 2010

AbstractX-ray photoelectron spectroscopy (XPS) has become increasingly important over the past few years for supporting the development of ultra-thin layers for high-k metal gates. As the analysis depth of XPS is however limited to about 5-7 nm, it would be extremely useful if the analysis could be carried out from the backside using standard silicon wafers. This approach puts extreme requirements on the sample preparation as hundreds of micrometers of bulk silicon have to be removed and one has to stop with nanometer precision when reaching the interface to the ultra-thin layer stack. Therefore, we have developed dedicated procedures for preparing and analyzing samples for backside XPS analysis. This paper presents the developed approach with a focus on sample preparation using plan-parallel polishing, endpoint detection by interference fringes, and selective wet etching. First angle-resolved XPS (ARXPS) analysis results of metal gate stacks demonstrate the power of such backside analysis.
Quantitative Characterization of the Interface Between a V2O3 Layer and Cu3Au (001) by Cs Corrected HREM
Authors: Calderon Hector Alfredo , Niehus Horst , Freitag B. , Wall D. , Stavale Fernando , Achete Carlos 
Published: August 2010

AbstractVanadium oxides are materials of interest due to their electronic, magnetic and catalytic properties. In the case of V2O3 and Cu3Au, the interfacial bonding is rather difficult to describe since the two component materials have strongly different electronic structures. Thus a local investigation of the interface becomes important. In this investigation, the incoherent interface between a V2O3 (0001, corundum structure) layer and a Cu3Au (001, L12 structure) substrate is characterized with the help of image corrected high resolution electron microscopy (HRTEM) and focal series reconstruction in order to investigated both the true position of atoms and the nature of the atomic species. Semi-quantitative results can be shown for the chemical composition of columns and strains at one side of the interface.
Hierarchical Design and Nanomechanics of the Calcified Byssus of Anomia simplex
Authors: Eltzholtz Jakob R , Krogsgaard Marie , Birkedal Henrik 
Published: August 2010

AbstractBiology has evolved several strategies for attachment of sedentary animals. In the bivalves, byssi abound and the best known example being the protein-based byssus of the blue mussel and other Mytilidae. In contrast the bivalve Anomia sp. has a single calcified thread. The byssus is hierarchical in design and contains several different types of structures as revealed by scanning electron microscopy images. The mechanical properties of the byssus are probed by nanoindentation. It is found that the mineralized part of the byssus is very stiff with a reduced modulus of about 67 GPa and a hardness of ˜3.7 GPa. This corresponds to a modulus roughly 20% smaller than that of pure calcite and a hardness that is about 20% larger than pure calcite. The results reveal the importance of microstructure on mechanical performance.
Substrate effect on Dynamic Indentation Measurement of Biological Cell Properties
Authors: Cao Guoxin , Chandra Namas 
Published: August 2010

AbstractViscoelastic mechanical properties of biological cells are commonly measured using atomic force microscope (AFM) dynamic indentation method with spherical tips. Storage and loss modulii of cells are then computed from the indentation force-displacement response under dynamic loading conditions. It is shown in current numerical simulations that those modulii computed based on existing analysis can not reflect the true values due to the substrate effect. This effect can alter the indentation modulus by changing the geometric relations between the indentation displacement and the contact area. Typically, the cell modulii are significantly overestimated in the existing indentation analysis.
Stress Liner Proximity Technique to Enhance Carrier Mobility in High-κ Metal Gate MOSFETs
Authors: Guo Dechao , Schonenberg Kathryn , Chen Jie , Jaeger Daniel , Kulkarni Pranita , Kwon Unoh , Liang Yue , Liu Joyce , Song Liyang , Arnaud Franck , Bu Huiming , Chudzik Michael , Henson William K , Oldiges Philip J , Sherony Melanie , Steegen An , Thean Voon-Yew , Khare Mukesh 
Published: August 2010

AbstractFor the first time, we discuss the compatibility of stress proximity technique (SPT) with dual stress liner (DSL) in high-κ/metal gate (HK/MG) technology. The short-channel mobility enhancement and the drive current improvement brought by SPT have been demonstrated at 32nm technology node. With maintained short channel control and threshold voltage roll-off characteristics, SPT has achieved 7% drive current improvement for both nFET and pFET from the optimization of SPT with DSL.
Novel Zirconium Formamidinate Precursor for the ALD of ZrO2
Authors: Li Huazhi , Shenai Deo V , Lehn Jean-Sebastien 
Published: August 2010

AbstractZirconium tetrakis(N,N’-dimethylformamidinate), Zr-FAMD, was synthesized and evaluated as a precursor for the deposition of zirconium oxide (zirconia) thin films via Atomic Layer Deposition (ALD) technique. Zr-FAMD has a high vapor pressure and displays an exceptionally high thermal stability; it is thus well-suited to be used as a precursor for the deposition of zirconia thin films. Zr-FAMD is a more ideally-suited precursor than tetrakisethylmethylaminozirconium or TEMAZr, which has an equivalent vapor pressure, but is plagued with a rather low thermal stability, limiting its usefulness at high deposition temperatures. Zr-FAMD can be used to deposit zirconia thin films at temperatures as high as 375 °C without evidence of decomposition.
Effects of Mechanical Strain on the Electrical Performance of Amorphous Silicon Thin-Film Transistors with a New Gate Dielectric
Authors: Song Katherine Wei , Han Lin , Wagner Sigurd , Mandlik Prashant 
Published: August 2010

AbstractThe stiff SiNx gate dielectric in conventional amorphous silicon thin film transistors (TFTs) limits their flexibility by brittle fracture when in tension. We report the effect on the overall flexibility of TFTs of replacing the brittle SiNx gate dielectric with a new, resilient SiO2-silicone hybrid material, which is deposited by plasma enhanced chemical vapor deposition. Individual TFTs on a 50μm-thick polyimide foil were bent to known radii, and measurement of transfer characteristics were made both during strain and after re-flattening. Compared with conventional TFTs made with SiNx, TFTs made with the new hybrid material demonstrated similar flexibility when strained in compression and significantly increased flexibility when strained in tension. Under bending to compressive strain, all TFTs tested delaminated from the substrate for compressive strains greater than 2%. Conventional a-Si:H/SiNx TFTs have been previously found to delaminate at a similar compressive strain. Under bending to tensile strain, the most flexible TFTs made with the new hybrid material that were tested after re-flattening did not exhibit significant changes in transfer characteristics up to strains of ∼2.5%. Conventional a-Si:H/SiNx TFTs have been found to remain functional for strains of up to 0.5%, a value only one-fifth of that for TFTs made with the new hybrid material.