bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Spectral Emissions from Laser Irradiated Titanium
Authors: Akarapu Ravindra Kumar , Dua Puneit , Campbell Alan , Scott Dana , Nassar Abdalla , Todd Judith , Copley Stephen 
Published: April 2011

AbstractTitanium nitride (TiN) is a candidate material for hard and wear resistant coatings on metallic substrates such as titanium (Ti), stainless steel and aluminum. Coating processes include chemical vapor deposition, ion implantation, plasma and thermal nitriding under vacuum and controlled environments. The motivation for the present research is to develop a laser plasma process for high rate formation of TiN coatings on Ti substrates at near-atmospheric pressures. Laser induced plasma generated by a pulsed CO2 laser was used to excite a Ti substrate. The species in the vapor plume were characterized by optical emission spectroscopy. Spatially and temporally resolved spectral characterization was performed as a function of laser power, position of the substrate relative to the focal plane, pulse parameters, and shielding gases. These experiments are a first step in understanding laser assisted plasma deposition of nitride/oxy-nitride coatings on titanium metal under atmospheric conditions. Results indicate a window of optimal process parameters for developing titanium nitride coatings.
Mn charge states in GaMnN as a function of Mn concentration and co-doping
Authors: Malguth Enno , Hoffmann Axel , Gehlhoff Wolfgang , Kane Matthew H. , Ferguson Ian T. 
Published: April 2011

AbstractIn the context of the pursuit of a dilute magnetic semiconductor for spintronic applications, a set of GaMnN samples with varying Mn concentration and Si or Mg co-doping was investigated by optical and electron spin resonance spectroscopy. The results clearly demonstrate how the charge state of Mn is changed between 2+, 3+ and 4+ by Mg and Si co-doping. For p-type GaMnN we show that the introduction of the Mn3+/4+ donor can be compensated by Mg co-doping lowering the Fermi energy below the Mn3+/4+ level. While our results are in agreement with the hypothesis that the infrared photoluminescence appearing in GaMnN upon Mg doping originates from Mn4+, an unambiguous proof is still to be presented. Under this assumption, our measurements show that the Mn4+ center must be excited via an extra-center process at 2.54 eV.
Thermal Volatilisation Analysis – The Development of a Novel Technique for the Analysis of Conservation Artifacts
Authors: Lewicki James Pawel , Todd Deborah , Redon Perrine , Liggat John , Gibson Lorraine 
Published: April 2011

AbstractReported here is the development of a novel evolved gas analysis technique; Sub-Ambient Thermal Volatilization Analysis (SATVA) and its application in characterizing key analyte species from conservation artifacts. In this work SATVA has been applied to the study of volatiles evolution processes occurring in number of model conservation artifacts. The evolution of volatile species from cured formaldehyde resin, leather and metallic artifacts has been studied by SATVA. The specific analytes making up the total quantity of evolved material in each case have been separated and identified using sub-ambient differential distillation and a combination of online mass spectrometry, gas phase IR spectroscopy and GC-MS. The data gathered has been used to provide information on both the degradation processes occurring within the artifacts and the environmental history of the artifacts themselves.
Plasma-enhanced chemical vapor deposition of carbon nanotubes using alcohol vapor
Authors: Okita Atsushi , Suda Yoshiyuki , Maekawa Masayuki , Takayama Junichi , Oda Akinori , Sugawara Hirotake , Sakai Yosuke 
Published: April 2011

ABSTRACTWe have successfully grown carbon nanotubes (CNTs) by alcohol plasma-enhanced chemical vapor deposition (PECVD). When 0.01 wt% ferrocene was added to alcohol, vertically-aligned CNTs could be grown using RF (= 13.56 MHz) plasma at 650°C. In contrast, no CNTs were obtained by pure alcohol PECVD. To understand the plasma properties for CNT growth, especially plasma species containing a gas phase of alcohol plasma, we analyzed the plasma using optical emission spectroscopy (OES) and quadrupole mass spectrometry (QMS). From the OES measurement, one could identify the emission peaks from the excitation states of CHO, CO, C2, O2, H, CH+, and H2O+, while the QMS measurement also showed the existence of CO, H2O, and CxHy (x≥2, y≥2). It is considered that such plasma species affect CNT growth by changing the oxidation state of the catalyst or by adjusting the amount of precursor species in the plasma. Comparing this PECVD experiment with thermal alcohol CVD (without plasma), only PECVD can be used to grow CNTs under the reported experimental conditions. It is considered that thermal alcohol CVD requires more energy to grow CNTs because 650°C is a little lower than the temperature required for CNT growth. These results indicate that in alcohol plasma, the active species produced by decomposition and recombination reactions have a possibility to promote/suppress CNT growth depending on the process conditions.
Rosette Nanotubes: Factors Affecting the Self-assembly of the Monobases Versus the Twin Base System
Authors: Hemraz Usha , Fenniri Hicham 
Published: April 2011

ABSTRACTRosette Nanotubes (RNTs) are formed by the self-assembly of a guanine-cytosine motif (GΛC), a hybrid of the DNA bases guanine and cytosine, to give a six membered macrocycle maintained by 18 H-bonds. In theory, any moiety covalently attached to the GΛC base can be expressed on the nanotubes surface. However we anticipate that the self-assembly and stability of these functionalised RNTs will also be governed by steric effects. Herein we describe the synthesis and the self assembly of the Twin Base Lysine (TBL-K) and its monobase (MBL-K). While TBL-K self-assembles readily in water and methanol to give nanotubular structures, MBL-K does not form nanotubes. Various techniques were used to characterize the RNTs and the factors, preventing self-assembly in the case of MBL-K, were investigated.
Engineered large area fabrication of ordered InGaAs-GaAs nanotube arrays
Authors: Chun Ik Su , Verma Varun B , Li Xiuling 
Published: April 2011

ABSTRACTStrain induced self-rolling semiconductor micro and nanotubes and related structures represent a new class of building blocks of nanotechnology. They are formed when strained planar bilayers are released from the substrate by selectively removing the sacrificial layer. Compared to other nanotechnology building blocks, one of the main advantages is the precise positioning capability due to top down fabrication approach. In this article, we demonstrate the fabrication of perfectly aligned arrays of InGaAs/GaAs nanotubes and the dispersion of freestanding semiconductor nanotubes into solution and onto foreign substrates. In addition, we systematically investigate the crystal orientation dependence of the rolling direction by using a wheel configuration. Other aspects of formation process are also discussed.
Self-assembly of Silicon Nanotubes
Authors: Xie Ming , Wang Jiesheng , Lee Chee Huei , Yap Yoke Khin 
Published: April 2011

ABSTRACTThe growth of silicon nanotubes (SiNTs) by a dual-RF-plasma treatment technique is reported here. These SiNTs are vertically aligned and self-assembled from Si substrates at 500 degree Celsius by the use of Cu catalysts. Their diameters are ∼50 to 80 nm with tubular wall thickness of ∼10-15nm. Cu vapors were found partially filled inside the SiNTs. This is a novel technique that can convert bulk materials into their nanostructures.
Low Temperature Synthesis of Carbon Nanotube on Si substrate Using Alcohol Gas Source in High Vacuum
Authors: Maruyama Takahiro , Tanioku Kenji , Naritsuka Shigeya 
Published: April 2011

ABSTRACTConventional alcohol catalytic chemical vapor deposition (ACCVD) growth of carbon nanotubes (CNTs) have been carried out under ambient gases from 103 to105 Pa. These ambient gas pressures have prevented in situ observations using an electron beam during CNT growth, such as scanning electron microscopy (SEM), scanning tunneling microscopy (STM). Therefore, in order to realize the in situ observations and to clarify the growth mechanism of nanotube, CNT growth in a high vacuum is essential. In addition, the effects of residual gases also may be avoided in the growth under high vacuum. In this study, we carried out CNT growth under high vacuum using an alcohol gas source in an ultrahigh vacuum (UHV) chamber and we achieved CNT growth below 400°C without any excitation processes of carbon source. After deposition of Co catalyst of 1 nm in thickness on SiO2/Si substrate, ethanol gas was supplied to the substrate surface through a stainless steel nozzle in the UHV chamber. The growth temperature was monitored by a pyrometer during the growth, and set between 350 and 900°C. The supply of ethanol gas was controlled by monitoring an ambient pressure, which was varied from 1 ∼10-1 to 1 ∼10-4 Pa. The grown CNTs were characterized by SEM and Raman spectroscopy. The G/Si intensity ratio reached its maximum at 700°C, when the pressure was 1 ∼10-1 Pa. The maximum point of the G/Si peak intensity shifted to a lower temperature as the growth pressure decreased. When the pressure was 1 ∼10-4 Pa, the G/Si intensity ratio reached its maximum at 400°C, at which clear RBM peaks were observed in the Raman spectrum. From the RBM peaks, the CNT diameters were estimated to be between 0.9 to 1.7 nm, and CNTs of 1.2-1.4 nm in diameter were dominant at 1 ∼10-1 Pa, whereas thinner CNTs (diameter is below 1.0 nm) were increased with the reduction of the pressure. Our largest G/D ratio was about 40 for the sample grown at 1 ∼10-1 Pa, which is considerably larger than the reported value for the CNTs grown under low pressure. From these results, we conclude that the reduction of the growth pressure lowers the growth temperature. This technique can be applied to in situ observation, and may also be useful for low temperature growth of CNTs, which opens new possibilities for the fabrication of CNT based nanodevices.
Influence of Nanotubes and Other Nanofillers on the Properties of Thermoset:thermoplastic Blends for Composite Matrices
Authors: Kilbride Marianne , Pethrick Richard Arthur , Ward Steven , Harriman Mark 
Published: April 2011

ABSTRACTRecently there has been an increase in the use of composite materials for aircraft construction. Composites have significant production and application advantages, but generally suffer from being electrically insulating, and hence are unable to handle a lightening strike in the traditional way that aluminium would. A potential solution to this problem is sought through the use of carbon nanotubes and carbon nanographite. Achieving the correct dispersion of the conducting filler is critical to achieving the desired enhancement in conductivity. Two different methods have been explored to achieve the dispersions; – direct blending and solution dispersion, with a range of concentrations of nanographite being incorporated. In addition, the effect of directly blending graphite nanoplatelets and carbon nanotubes in order to create a hybrid nanocomposite material was studied. The carbon nanotubes were incorporated into a blend with the graphite nanoplatelets with the intention of utilizing their tube structure in order to bridge the gaps between the platelet sheets of nanographite, creating more effective and abundant conductive pathways throughout the composite. In all cases the electrical conductivity was measured using a four point probe technique.
A Study of Conformal GaAs on Si Layers by Micro-Raman and Spectral Imaging Cathodoluminescence
Authors: Martínez Oscar , Sanz Luis Felipe , Jiménez Juan , Gérard Bruno , Gil-Lafon Evelyn 
Published: April 2011

ABSTRACTSpectral imaging cathodoluminescence and micro-Raman spectroscopy studies of GaAs layers grown on Si substrates by the conformal method allow to reveal a great variety of physical features of the layers, such as the complete stress distribution, self-doping effects, or the incorporation of dopants. We present herein the characterization of GaAs conformal layers grown by hydride vapor phase epitaxy, where the main issues concerning the distribution of defects and stresses are revealed. Also, intentionally doped layers were analyzed, revealing the main aspects of the incorporation of dopant impurities during growth.
Simulation of Forescattered Electron Channeling Contrast Imaging of Threading Dislocations Penetrating SiC Surfaces
Authors: Twigg Mark E. , Picard Yoosuf N. , Caldwell Joshua D. , Eddy Charles R. , Neudeck Philip G. , Trunek Andrew J. , Powell J. Anthony 
Published: April 2011

ABSTRACTThe interpretation of ECCI images in the forescattered geometry presents a more complex diffraction configuration than that encountered in the backscattered geometry. Determining the Kikuchi line that is the primary source of image intensity often requires more than simple inspection of the electron-channeling pattern. This problem can be addressed, however, by comparing recorded ECCI images of threading screw dislocations in 4H-SiC with simulated images. An ECCI image of this dislocation is found to give the orientation of the dominant Kikuchi line, greatly simplifying the determination of the diffraction simulation. In addition, computed images of threading screw dislocations in 4H-SiC were found to exhibit channeling contrast essentially identical to that obtained experimentally by ECCI and allowing determination of the dislocation Burgers vector.
MOVPE Growth and Characterization of AlInN FET Structures on Si(111)
Authors: Hums Christoph , Gadanecz Aniko , Dadgar Armin , Bläsing Jürgen , Witte Hartmut , Hempel Thomas , Dietz Annette , Lorenz Pierre , Krischok Stefan , Schaefer Jürgen Alois , Christen Jürgen , Krost Alois 
Published: April 2011

ABSTRACTIn this work metalorganic chemical vapor phase epitaxy (MOVPE) growth and characterization of AlInN in the whole compositional range and the impact on the development of field effects transistors (FET) structures will be presented. Due to the large difference in the lattice parameters of the binaries AlN and InN the growth of AlInN with high indium concentrations is ambitious, and first the growth conditions for the alloy will be discussed. An experimental phase diagram and corresponding theoretical calculations will be displayed. The critical layer thickness of AlInN on GaN has been experimentally determined. Relaxation of the AlInN-layer has a strong influence on the sample morphology. At indium concentration exceeding 30% an polarization induced hole gas is expected at the AlInN/GaN interface from theoretical calculations, but no p-channel conductivity could be confirmed. The absence of the two dimensional hole gas will be discussed.
Impact of the High-Temperature Process Steps on the HfAlO Interpoly Dielectric Stacks for Nonvolatile Memory Applications
Authors: Ruiz Aguado Daniel , Govoreanu Bogdan , Favia Paola , De Meyer Kristin , Van Houdt Jan 
Published: April 2011

AbstractThis work reports on the performance of different Hafmiun aluminate (HfAlOx)-based interpoly dielectrics (IPD) for future sub-45nm nonvolatile memory (NVM) technologies. The impact of the thermal budget during the fabrication process is studied. The good retention and large operating window shown by this material, can be compromised by a high temperature activation anneal (AA) after the gate deposition. The AA step may induce phase segregation of the HfAlOxand outdiffusion of the Hf (Al) towards the floating gate/IPD and IPD/gate interfaces and subsequent formation of Hf (Al) silicates. These findings are supported by the low field leakage analysis, which shows large device to device dispersions. However, the effect of the spike anneal can be minimized if the HfAlOxlayer is crystallized prior to the AA. Devices with polysilicon or TiN gate are compared in terms of memory performance and reliability.
Ferroelectric and Electrical Properties of BaZrO3 Doped Sr0.8Bi2.2Ta2O9 Thin Films
Authors: Bozgeyik Mehmet S. , Cross J. S. , Ishiwara H. , Shinozaki K. 
Published: April 2011

AbstractBaZrO3 (BZO) doped Sr0.8Bi2.2Ta2O9 (SBT), a new modified SBT, thin films were prepared and related ferroelectric and electrical properties were evaluated.
Organic Single Crystal Transistors Gated by Electric Double Layers in Ionic Liquid
Authors: Hirahara R. , Ono S. , Seki S. , Tominari Y. , Takeya J. 
Published: April 2011

AbstractGating organic transistors with electric double layers (EDL) of electrolytes is advantageous in injecting high-density carriers with the application of minimum gate voltage. The drawback of such devices, however, has been that commonly used polymer electrolytes suffer relatively slow ionic diffusion before forming the EDLs. In this report, we disclose a new class of EDL devices incorporating low-viscosity room temperature ionic liquid as the electrolyte layer, so that the rapid ionic diffusion allows MHz operation for the transistor performance. We fabricate a well structure using an elastomeric rubber stamp of poly-dimethylsiloxane to hold the ionic liquid 1-ethyl 3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide, known for high ionic conductivity. The transistor performs without hysteresis with the carrier mobility of 5 cm2V−1s−1, realizing the highest sheet transconductance ever achieved.
Synthesis and Characterization of Structured Metal/Silica Clusters
Authors: Patil A.N. , Otsuka N. , Andres R.P. 
Published: April 2011

ABSTRACTThe synthesis of two component clusters of Au/SiO2, Ag/SiO2 and Cu2O/SiO2 is described. These heteronuclear clusters are synthesized as metal/silicon clusters of controlled composition and controlled size using a novel gas aggregation source and by means of gas phase annealing are transformed into ‘structured’ particles. The final metal/oxide and oxide/oxide clusters are formed by air exposure. The structure of these nanostructured particles is determined by electron diffraction and transmission electron microscopy (TEM). The clusters exhibit two distinct structural forms: (1) clusters consisting of a metal rich core surrounded by a silicon rich skin and (2) clusters having a metal rich domain and a silicon rich domain separated by a sharp interface.
Tem Studies on the Morphology, Size Distribution and Structure of Nanocrystalline Iron Particles Using a Formvar Embedded Preparation Technique
Authors: Ni Hengfei , Bi Xiangxin , Stencel John M. 
Published: April 2011

ABSTRACTA new, simple and effective method was developed for preparing specimens of Fecarbide ultrafine particles (UFP), by suspending them in Formvar films. Various samples of Fe-carbide UFP's were obtained by a laser pyrolysis process by varying the process parameters. The UFP samples were mixed with different concentrations of Formvar in ethylene dichloride solution. The sample particles were embedded in ultra-thin Formvar films with thickness of 20 nm or more and mounted on the 200 mesh copper TEM grids. The influences of the concentration of the Formvar solution and the amount of sample powder on the UFP distribution in the micrographs were investigated to determine the optimal film-making parameters. The different sizes and same spherical morphology for the various UFP samples were revealed, indicating the main diameters to be between 5–20 nm. Compared with the size values obtained by using XRD, the UFP size measurements by the new process are in good agreement. The crystalline features and the surface of the UFP's are presented and confirmed by micro-diffraction studies.
Challenges and Opportunities in Magnetic Resonance Force Microscopy
Authors: Sidles John A. , Garbini Joseph L. 
Published: April 2011

ABSTRACTRecently the first experiments in magnetic resonance force microscopy (MRFM) have been conducted. In these experiments a force microscope cantilever is used to detect the magnetic force exerted by electrons and nuclei in a sample. The magnetization of the sample is modulated at the resonant frequency of the cantilever, using standard magnetic resonance techniques. The resulting excitation of the cantilever is detected optically. This article reviews the present status of MRFM technology, emphasizing the physical principles involved and the opportunities for further research and development. Particular emphasis is placed on single spin detection by MRFM and potential applications in biomolecular imaging.
Microstructural Imaging of Localized Chemical Reactions using Valence Photoelectrons
Authors: Liang S. , Ray-Chaudhuri A.K. , Ng W. , Cerrina F. 
Published: April 2011

ABSTRACTWe have utilized scanning soft X-ray photoelectron spectromicroscopy-MAXIMUM to investigate the microstructural evolution induced by localized corrosion in the Al-Cu-Si alloy thin films. We present energy-specific photoelectron micrographs showing the distribution of Cu-rich precipitates and corrosion products for the thin films after corrosion. Microspectroscopy performed across a corrosion site reveals that the O 2p valence band shifts in energy with location and the amount of shift can be related to the degree of corrosion. The photoelectron micrographs also show that the Cu-rich phase precipitates near the surface region and grows with annealing temperature.
Electromigration Characteristics of Cu and Al Interconnections
Authors: Shingubara S. , Fujiki K. , Sano A. , Sakaue H. , Horiike Y. 
Published: April 2011

ABSTRACTElectromigration activation energies (Ea) of Al and Cu interconnections are strongly dependent on the grain boundary morphology, and it is pointed out that Ea of bamboo-like Al interconnection is not less than Ea of small grain Cu interconnections. Small resistance oscillatory changes caused by electromigration, which are classified into three categories; oscillation, downward spikes, and upward spikes, are investigated in detail. It seems most likely that oscillations correspond to annihilation and formation of the one void. It is also pointed out that downward spikes are local, while upward spikes are non-local. Dislocation dynamics such as generation, rapid transport and subsequent annihilation are considered to be origins of spikes.
Measurement of Adhesion at Film -Substrate Interfaces by Constant Depth Scratch Testing
Authors: Dutta I. , Lascurain D. P. , Secor E. D. 
Published: April 2011

ABSTRACTQuantitative tests for interfacial adhesion between films and substrates are of criticalimportance in micro-electronic applications. However, many of the available tests are applicable to a limited array of materials systems, or are experimentally complex. In thispaper, a constant depth scratch test, which has been designed to circumvent the limitations associated with currently available tests, is presented along with theoretical developments for the quantification of interfacial shear strength. Because of a fixed scratchgeometry, the test is amenable to straightforward analytical formulations unlike other versions of scratch tests. It is unique in its experimental simplicity, and allows evaluation of interface strength as function of position on the sample. Sample outputs from the test based on Cr films on glass substrates are presented.
Excess Conductance of MOS Diodes Suffered Current Stress and Elucidation of Induced Interface States
Authors: Inoue Masao , Shirafuji Junji 
Published: April 2011

ABSTRACTThe ac conductance-voltage (G–V) characteristics at various frequencies have been measured in MOS diodes which suffered constant current stress by Fowler–Nordheim (F–N) electron injection from Si substrate.It is found that a double-peak structure appears in G–V curve and grows continuously with proceeded current stress.The growth of two kinds of interface states is elucidated after subtracting the effect of oxide capacitance and substrate resistance by a simple equivalent circuit analysis.