bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Ionized Carbon Plasma Generation by Dual-Laser Ablation for Diamond-Like Carbon Film Growth
Authors: Witanachchi S. , Miyawa A. M. , Mukherjee P. 
Published: April 2011

AbstractCarbon plasmas produced by excimer laser ablation show a low ionization yield of about 8-10%. The coupling of a second CO2laser pulse into the plasma in the dual-laser ablation process significantly increases the plasma temperature and the ionization. The resulting rapid expansion of the plasma gives rise to high ion kinetic energies and broader ion expansion profiles [1]. Optical emission spectroscopy and an ion probe have been used to investigate the dynamics of the carbon plasma. Single and dual-laser ablated carbon plumes have been deposited on DC-biased silicon substrates to form amorphous carbon films. The diamond-like behavior of these films was studied by Raman spectroscopy. The Raman spectra were deconvolved to gauge the effect of the density and the energy of ions on the formation of diamond-like sp3 -bonded carbon (DLC) films. The advantage offered by the dual-laser process for the growth of DLC films is discussed.
Ordered Thin Films of Perylenetetracarboxylicdianhydride-bisimide and bis-(N-alkyl)-Quinacridone Dyes
Authors: Back Andrew , Alloway Dana , Schlettwein Derck , Schilling Brook , Wang J.-F. , Carducci Mike , Armstrong Neal R. 
Published: April 2011

ABSTRACTWe review here the recent characterization of vacuum deposited monolayer and multilayer thin films of two different perylenetetracarboxylic-dianydride-bisimides (Cn-PTCDI; n =4,5), quinacridone, and two new bis-(N-alkyl)-quinacridone dyes (DIQA and DEHQA) on single crystal alkali halides using a combination of in situ luminescence spectroscopies and ex situ tapping mode AFM. Flat lying monolayer structures are indicated for PTCDA on the (100) faces of NaCl, KCl and KBr, for C4-PTCDI on KCl, for C5-PTCDI on both KCl and KBr and for DIQA on both KCl and KBr. Coherent thin films, exhibiting layer-by-layer growth can be achieved for PTCDA on all substrates, for C4-PTCDI on KCl and for DIQA on both KBr and KCl. Both C4-PTCDI and DIQA appear to fulfill the requirements for dyes which exhibit layered growth with the molecular plane inclined at steep angles to the surface normal.
Macromolecular Crystals in the Service of Biotechnology and Medicine
Authors: Mcpherson Alexander 
Published: April 2011

ABSTRACTThe application of genetic and molecular biological methods to the engineering of proteins, the engine of the biotechnology revolution, has become increasingly dependent on knowledge of protein, nucleic acid and virus molecular structure. Structural information of high precision, essential to this enterprise, can only be obtained through X-ray crystallographic techniques. The quality of this information is directly a function of the properties and degree of perfection of the crucial intermediates, the macromolecular crystals. As a consequence, there is now broad and intense interest in developing new methods, procedures and reagents for the nucleation and growth of such crystals. There is, in addition, an expanded interest in the properties of biological crystals and the use of physical measurements in improving approaches to growing better and larger crystals. Here some of the fundamentals of macromolecular crystal growth will be reviewed, and some current trends in the field remarked upon, including the new initiative to develop a national structural genomics program.
Moving Steps and Crystal Defects on Spinel Surfaces
Authors: Yanina S.V. , Carter C.B. 
Published: April 2011

ABSTRACTThe morphology of the reconstructed {001} surface of MgAl2O4 spinel is studied by scanning probe microscopy (SPM). The observations show that the {001} surface of MgAl2O4 may exist as two variants which are related through 90° rotation about the [001] axis. These surface variants exhibit different lateral forces and tend to grow/evaporate and to etch anisotropically along either the [110] or the [110] directions of the crystal. Surface terraces that are formed by different variants were found to be separated by ∼2.0 Å-high steps, while the terraces which belong to the same variant are separated by ∼4.0 Å-high steps. It is expected that the origins of the preferential motion of ledges on the {001} spinel surface is related to the anisotropic distribution of cations along either the [110] or the [110] directions within the {001} crystal planes in the spinel crystal.
Resolving the Control of Magnesium on Calcite Growth: Thermodynamic and Kinetic Consequences of Impurity Incorporation for Biomineral Formation
Authors: Davis Kevin J. , Dove Patricia M. , Yoreo James J. De 
Published: April 2011

ABSTRACTMagnesium is a key determinant in CaCO3 biomineral formation and has recently emerged as an important paleotemperature proxy. Atomic force microscopy (AFM) was used to determine the fundamental thermodynamic and kinetic controls of Mg2+ on calcite morphology and growth. Comparison of directly measured monomolecular step velocities (vs±) to theoretical crystal growth impurity models demonstrated calcite inhibition due to enhanced mineral solubility through Mg2+ incorporation. Terrace width (λ) measurements independently supported an incorporation mechanism by indicating a shift in the effective supersaturation (σeff) of the growth solutions in the presence of Mg2+. This study resolves the controversy over the molecular-scale mechanism of calcite inhibition by Mg2+ and provides an unambiguous model for the thermodynamic and kinetic consequences of impurity incorporation into CaCO3 biominerals.
Defect population and electrical properties of Ar+-laser crystallized polycrystalline silicon thin films
Authors: Christiansen S. , Nerding M. , Eder C. , Andrae G. , Falk F. , Bergmann J. , Ose M. , Strunk H. P. 
Published: April 2011

ABSTRACTWe crystallize amorphous silicon (a-Si) layers (thicknesses: ∼300nm and ∼1300nm for comparison) that are deposited on glass substrates (Corning 7059) by low pressure chemical vapor deposition using a continuous wave Ar+-laser. We scan the raw beam with a diameter of ∼60νm in single traces and traces with varying overlap (30-60%). With optimized process parameters (fluence, scan velocity, overlap) we achieve polycrystalline Si with grains as wide as 100νm. The grain boundary population is dominated by first and second order twin boundaries as analyzed by electron backscattering analysis in the scanning electron microscope and convergent beam electron diffraction in the transmission electron microscope. These twins are known not (or only marginally) to degrade the electrical properties of the material. In addition to twins, dislocations and twin lamellae occur at varying densities (depending on grain orientation and process parameters). The recombination activity of the defects is analyzed by EBIC and according to these measurements crystallization receipts are defined that yield the reduction of electrically detrimental defects.
Surface Treatment on Silicon Field-Emission Cathodes
Authors: Hajra M. , Chubun N.N. , Chakhovskoi A.G. , Hunt C.E. 
Published: April 2011

ABSTRACTArrays and single-tip p-type silicon micro-emitters have been formed using a subtractive tip fabrication technique. Following fabrication, several different surface treatments have been attempted for comparison. We utilized ion and electron bombardment at elevated pressures (with interrupted pumping), and also hydrogen seasoning during field emission operation. The objectives of these treatments include stabilization of the emission, lowering the effective workfunction, and reducing low-frequency noise. The tips were evaluated using I-V measurements in the diode configuration. A flat Si anode, spaced nominally 6 μm and 150 μm from the cathode, was used. For the purpose of treatment, the field emission characteristics are measured in a high vacuum chamber at a pressure range between 10−5 and 10−8 Torr. The results suggest that the emitters benefit from seasoning or conditioning, for optimal performance, low noise, minimum work function and maximum reproducibility and reliability over the lifetime of the cathode.
Solid-State Field-Controlled Electron Emission: An alternative to thermionic and field-emission
Authors: Binh Vu Thien , Dupin J.P. , Thevenard P. , Guillot D. , Plenet J.C. 
Published: April 2011

ABSTRACTIn the solid-state field-controlled emitter (SSE), the emission barrier, which is the factor of utmost importance for surface electron emission, is tailored by a controlled extrinsic parameter like the injected space charge located near the surface. This is done by depositing an ultra-thin wide band-gap semiconductor layer on a metallic surface. It is an alternative approach to the thermionic or field emission for which the work function value is intrinsic to the material used. The emission current measurements from the SSE cold cathodes show stable emission, at low applied field (≈50 V/μm) and in poor vacuum (≈10−7 Torr). The new emission mechanism has been modeled, the calculations and the theoretical analysis confirm the experimental results. The fabrication of the SSE, either by a sputter deposition in vacuum or by a sol-gel technique, meets most of the demands specific to high throughput fabrication of cold cathodes with large emitting area dedicated to applications in vacuum microelectronics.
Field Emitter Cathodes and Electric Propulsion Systems
Authors: Marrese Colleen M. , Polk James E. , Mueller Juergen 
Published: April 2011

ABSTRACTReplacing hollow and filament cathodes with field emitter (FE) cathodes could significantly improve the scalability, power, and performance of some meso- and microscale Electric Propulsion (EP) systems. The propulsion system environments and requirements and the challenges in integrating these technologies are discussed to justify the recommended cathode configurations. Required cathode technologies include low work function coatings on Si or Mo Field Emitter Array (FEA) cathodes with arc protection and electrostatic ion filters.
Electron Emission from Microwave-Plasma Chemically Vapor Deposited Carbon Nanotubes
Authors: Tzeng Yonhua , Liu Chao , Cutshaw Calvin , Chen Zheng 
Published: April 2011

ABSTRACTA microwave plasma CVD reactor was used for the deposition of carbon nanotubes on substrates. Hydrocarbon or oxyhydrocarbon mixtures were used as the carbon source. Hot electrons in the microwave plasma at temperatures exceeding 10,000C provided a means of dissociating the vapor or gas feedstock, heating the substrate, and allowing gas species to react in the gas phase as well as on the surface of the substrate leading to the deposition of desired carbon coatings. A high vacuum chamber was used to characterize the electron emission properties of these carbon nanotube coatings using a one-millimeter diameter tungsten rod with a hemispherical tip as the anode while the carbon nanotube coatings served as the cathode. The current-voltage characteristics of the carbon nanotube coatings were measured and used for calculating the electric field at which electron emission turned on as well as calculating the field enhancement factor of the carbon nanotubes. Field emission of electrons from carbon nanotubes starting from an electric field lower than 1 volt per micrometer has been achieved.
Hot-Filament Assisted Fabrication of Carbon-Nanotube Electron Emitters
Authors: Tzeng Yonhua , Liu Chao , Chen Zheng 
Published: April 2011

ABSTRACTA hot-filament CVD reactor was used for the deposition of carbon nanotubes on substrates. Hydrocarbon or oxyhydrocarbon mixtures were used as the carbon source. Hot filaments at temperatures exceeding 2000C provided a means of dissociating the vapor or gas feedstock, heating the substrate, and allowing gas species to react in the gas phase as well as on the surface of the substrate leading to the deposition of desired carbon coatings. A high vacuum chamber was used to characterize the electron emission properties of these carbon nanotube coatings using a one-millimeter diameter tungsten rod with a hemispherical tip as the anode while the carbon nanotube coatings served as the cathode. The current-voltage characteristics of the carbon nanotube coatings were measured and used for calculating the electric field at which electron emission turned on as well as calculating the field enhancement factor of the carbon nanotubes. Field emission of electrons from carbon nanotubes starting from an electric field of as low as 1-2 volts per micrometer was achieved.
Quantum Transport Through Intermolecular Nanotube Junctions
Authors: Buldum Alper , Lu Jian Ping 
Published: April 2011

AbstractQuantum transport properties of intermolecular nanotube contacts are investigated. We find that atomic structure in the contact region plays important roles and resistance of contacts varies strongly with geometry and nanotube chirality. Nanotube end-end contacts have low resistance and show negative differential resistance (NDR) behavior. Exerting small pressure/force between the tubes can dramatically decrease contact resistance, if the contact is commensurate. Significant variation and nonlinearity of contact resistance may lead to new device applications.
Well-aligned carbon nanofibers synthesized by electron cyclotron resonance chemical vapor deposition
Authors: Hoshi Fumiyuki , Tsugawa Kazuo , Goto Akiko , Ishikura Takefumi , Yumura Motoo , Koga Yoshinori , Yamashita Satoshi , Hirao Takashi , Fujiwara Shuzou , Yumura Motoo , Koga Yoshinori 
Published: April 2011

AbstractAligned carbon nanofibers and hollow carbon nanofibers were grown by MW ECR-CVD method using methane and argon mixture gas at the temperature of 550••. Carbon nanofibers and hollow carbon nanofibers were deposited perpendicularly on Si substrate and on Si substrate coated with Ni catalyst, respectively. Raman spectra of aligned carbon nanofibers and hollow carbon nanofibers showed new bands of 1340 and 1612 cm-1 of the first-order Raman scattering and 2660, 2940 and 3220 cm-1 of the second-order Raman scattering. The second-order Raman scattering bands were assigned to two overtone and one combination bands on the basis of a similar assignment of micro crystal graphite. Combination bands are intense unusually. Field emitter characteristics of the well-aligned carbon nanofibers and hollow carbon nanofiberswere investigated and the current densities were 7.25 mA/cm2 and 0.69 mA/cm2at 12.5 V/μm, respectively.
In-situ Fluid Experiments in Carbon Nanotubes
Authors: Gogotsi Yury , Libera Joseph A. , GüvenÇ Yazicioglu Almila , Megaridis Constantine M. 
Published: April 2011

AbstractClosed-end multi-wall carbon nanotubes, which contain an encapsulated aqueous multi-phase fluidunder high pressure, have been produced by hydrothermal synthesis. These nanotubes are leak-tight by virtue of holding the fluid at the high vacuum of a transmission electron microscope (TEM) and can be used as a testplatform for unique in-situ nanofluidic experiments in TEM. They form an experimental apparatus, which is at least two orders of magnitude smaller than the smallest capillaries used in fluidic experiments so far. Excellent wettability of the carbon tube walls by the liquid and a dynamic behavior similar to that in micro-capillaries demonstrates the possibility of use of nanoscale (<100 nm) tubes in nanofluidic devices.However, complex interface behavior that can potentially create hurdles to fluid transport is also demonstratedherein.
Quantum coherence in sub-10 nm metal wires
Authors: Natelson Douglas , Willett Robert L. , West Kenneth W. , Pfeiffer Loren N. 
Published: April 2011

AbstractWe report weak localization studies of quantum coherence in metal nanowires with widths as small as 5 nm, demonstrating that structures fabricated at sub-50 nm length scales can reveal coherence phenomena not accessible in larger devices. Through selective etching of cleaved molecular-beam epitaxy (MBE)-grown substrates, we produce precise nanoscale surface relief then used as a stencil for metal deposition. This nonlithographic method of lateral definition allows the fabrication of metal (AuPd) nanowires greater than one micron in length with widths below 5 nm, a previously unexplored size regime in studies of quantum corrections to the conductance of disordered metals. Analyzing magnetoresistance data, we find that the coherence time,Tφ, shows a low temperatureTdependence close to quasi-1D theoretical expectations (Tφ∼ T-2/3in 5 nm wide wires, while exhibiting a relative saturation asT0 for wide samples of the same material. Since an externally controlled parameter, the sample geometry, can cause a single material to exhibit both suppression and divergence ofTφ, this finding provides a new constraint on models of dephasing phenomena.
Basic:

B

io-Inspired

A

ssembly of

S

emiconductor

I

ntegrated

C

ircuits
Authors: Bashir R. , Lee S. , Guo D. , Pingle M. , Bergstrom D. , Mcnally H. A. , Janes D. 
Published: April 2011

AbstractIn the recent years, biologically-inspired self-assembly of artificial structures, some with useful optical properties, has been demonstrated. However, to date there has been no demonstration of self-assembly of useful electronic devices for the construction of complex systems. In this paper, a new process called BASIC (Bio-Inspired Assembly of Semiconductor Integrated Circuits) is proposed. The main theme is to use the mutual binding (hybridization) and specificity of DNA strands (oligonucleotides) for the assembly of useful silicon devices on silicon or other substrate. These devices need to be ‘released’ from their host substrate into a liquid medium where they can be functionalized with single stranded DNA. Silicon-on-insulator (SOI) substrates, which naturally lend themselves for such application, due to the presence of an oxide layer underlying the silicon layer, are used. These devices can vary in size and have a thin gold layer on one surface. This approach can be used to assemble micro and nano-scale devices and circuits and can also be a powerful technique for heterogeneous integration of materials (e.g. Si on Glass or polymer). The general idea of the BASIC process can also be extended to be used with any antibody/antigen complex. Preliminary results regarding the fabrication and release of the device islands will be presented. In addition, surface AFM characterization of the gold surfaces, prior to attachment of bio-molecules, is also presented.
Relation between Local Composition, Chemical Environment and Phase Shift Behavior in Cr-Based Oxycarbonitride Thin Films
Authors: Smith J.R. , Graat P.C.J. , Bonnell D.A. , French R.H. 
Published: April 2011

AbstractThe latest deep ultra-violet (DUV) photomask technology requires macroscopic properties such as optical transmission, reflectance, and chemical reactivity to be precisely controlled. Therefore, a fundamental understanding of the relationship between atomic bonding and nanometer scale property variation is required. Thin films of Cr-OC-N are compositionally graded to produce specific attenuation and phase shift of optical radiation. A combination of techniques was used to relate the local atomic bonding to macroscopic properties. Sputtered neutral mass spectroscopy was used to resolve local composition, and variable angle spectroscopic ellipsometry was used to determine local optical properties (on nm scale) that are then related to local composition. Core level shifts in X-ray photoelectron spectroscopy characterize changes in the Cr environment associated with changes in composition. A model is suggested in which bonding at the atomic level is controlled within different 10-100 nm sized regions which can be combined to produce arbitrary optical properties.
Method for Measuring Profiles of Photoacid Patterns in Chemically Amplified Resists
Authors: Feke Gilbert D. , Grober Robert D. , Pohlers Gerd , Cameron James F. 
Published: April 2011

AbstractWe describe a method based on single molecule probing of acid concentration to measure the profiles of photogenerated acid patterns in chemically amplified resist films. We further present preliminary data which demonstrates the viability of this method.
Magnetic Nanoparticle Arrays with Ultra-Uniform Length Electrodeposited in Highly Ordered Alumina Nanopores(“Alumite”)
Authors: Metzger Robert M. , Sun Ming , Zangari Giovanni , Shamsuzzoha Mohammad 
Published: April 2011

AbstractWe report nanometer-scale ordered arrays of cylindrical magnetic nanoparticles with low aspect ratio and ultra-high uniformity. Protracted anodization provides hexagonally ordered nanopores in amorphous Al2O3. For instance, pulsed electrochemical deposition grows Co particles of uniform length from the bottoms of these pores: these particles are polycrystalline and randomly oriented. The magnetism of the array is dominated by particle shape and by inter-particle magnetostatic interactions. A very clear transition of the anisotropy from perpendicular to in-plane is observed at a height to radius ratio of about 2. This pulse-reverse electrodeposition shows great promise for a reliable synthesis of uniform nanostructures of many metals.
Multiparametric sensor for air pollutants based on a porous silicon optical microcavity
Authors: Gaburro Z. , Faglia G. , Baratto C. , Sberveglieri G. , Pavesi L. 
Published: April 2011

AbstractWe experimentally demonstrate that porous silicon optical microcavities can be effectively used as multi-parametric gas sensors. As known, the photoluminescence intensity and electrical conduction of porous silicon are strongly dependent on environmental properties, such as the dipole moment of molecules of surrounding gases. The sensitivity is large due to the large surface/volume ratio of porous silicon. While these effects can be observed in any porous silicon structure, microcavities of porous silicon allow an additional sensing parameter, i.e. the spectral position of the resonance cavity peak. The position of the peak depends on the index of refraction of the environment, and gives independent additional information. Moreover, we show that the dynamic response of the peak shift is much faster comparing the other sensing parameters. The combined effects on the peak position, luminescence intensity and electrical conduction can allow discrimination between different substances, and therefore porous silicon optical microcavities can work as multi-parametric optical/electrical sensors. We report detection of 1 ppm of NO2 and 500 ppm of ethanol at room temperature. With NO2, the electrical conduction increases and PL quenches, but the peak does not shift, whereas the peak shifts with ethanol (no significant PL quenching is observed at 500 ppm). This suggests that discrimination between different species can be achieved.
Ion Beam Synthesis Based Formation of Ge – Rich Thermally Grown Silicon Dioxide Layers: A Promising Approach for A Silicon - Based Light Emitter
Authors: Gebel T. , Rebohle L. , Zhao J. , Borchert D. , Fröb H. , Borany J.V. , Skorupa W. 
Published: April 2011

AbstractThe development of novel devices for optical communication and integrated sensor applications is mainly focused on their possible integration into dedicated integrated circuits. The main problem concerning integrated optical systems in silicon technology has always been the formation of an highly efficient silicon-based light emitter which is a key feature to make a real step into the world of integrated optoelectronics.One of the most promising approaches to form such a silicon based light emitter is ion beam synthesis. In this paper we will report our recent progress in extracting blue-violet (∼400 nm) electroluminescence (EL) from an ion beam synthesized Ge-rich silicon dioxide layer. The power efficiency of the EL was as high as 0.5 % which is one of the best values ever reported for Si - based light emission. The lifetime of the EL-device can reach several hours without special precautions of stabilizing the EL-active layer against ion or other contamination. Moreover, results are reported dedicated to the investigation of the excitation mechanism of this strong EL.