bluuebunny/crossref_metadata_2025_split huggingface dataset:
How does an Ultrathin Cobalt Film Response to the Presence of a Neighboring Pentacene Layer
Authors: Chan Yuet-Loy , Hung Ya-Jyuan , Wang Chia-Hao , Lin Ying-Chang , Chiu Ching-Yuan , Lai Yu-Ling , Chang Hsu-Ting , Lee Chih-Hao , Hsu Yao-Jane , Wei Der-Hsin 
Published: February 2010

AbstractThe interfacial regimes of cobalt/pentacene/cobalt (Co/Pc/Co) trilayers were emulated through the ultrathin pentacene/cobalt (Pc/Co) and cobalt/pentacene (Co/Pc) bilayers. Employing the magneto-optical Kerr effect (MOKE) measurement, we found the coercivity of Co bottom film in a thickness of 3.4 nm experienced a slight reduction upon the adsorption of Pc molecules. For the bilayers prepared with reversed order of deposition, the Co film deposited on a 6.4 nm Pc layer showed no observable ferromagnetic order at room temperature until its thickness reached 3 nm. After the onset of magnetic order, the x-ray images acquired on Pc/Co revealed a complicated magnetization patterns comparing to those observed on Co/Pc bilayers. Because the spin-polarized carriers will interact with the environment along their transport path, the presence of a non-magnetic layer and the occurrence of complicated domain structures suggested the spin-polarized carriers would experience a greater disturbance on their spin coherence when crossing the Pc/Co interface.
Electronic and Magnetic Properties of Small Co-O Quantum Wires
Authors: Pozhar Liudmila A , Mavromichalis Constantine 
Published: February 2010

AbstractElectronic and magnetic properties of small Co-O atomic clusters (“quantum wires”) have been studied in the framework of the Hartree-Fock (HF) method. The obtained results indicate that non-stoichiometric Co - O molecules with more than two O atoms possess at least one remarkably stretchable O-O bond that may facilitate significant re-construction of such molecules to larger structures. This re-construction may result in energetically favorable spin re-alignment in “antiferromagnetic” HF singlet Co-O molecules converting the singlets to larger “ferromagnetic” HF triplets and pentets. Such a spin re-alignment is energetically favorable, and may happen at the antiferromagnet-ferromagnet interface in “critical” core (Co) – shell (CoO) exchange-biased nanoclusters, providing for minimization of the surface energy, and leading to a loss of exchange bias. The obtained results are in agreement with available experimental and computational data.
Magnetic and Electronic Properties of Fe0.1Sc0.9N/ScN(001)/MgO(001) Films Grown by Radio-Frequency Molecular Beam Epitaxy
Authors: Constantin Costel , Wang Kangkang , Chinchore Abhijit , Chia Han-Jong , Markert John , Smith Arthur R 
Published: February 2010

AbstractFe0.1Sc0.9N with a thickness of ˜ 380 nm was grown on top of a ScN(001) buffer layer of ˜ 50 nm, grown on MgO(001) substrate by radio-frequency N-plasma molecular beam epitaxy (rf-MBE). The buffer layer was grown at TS ˜ 800 oC, whereas the Fe0.1Sc0.9N film was grown at TS ˜ 420 oC. In-situ reflection high-energy electron diffraction measurements show that the Fe0.1Sc0.9N film growth starts with a combination of spotty and streaky pattern [indicative of a combination of smooth and rough surface]. After ˜ 10 minutes of growth, the pattern converts to a spotty one [indicative of a rough surface]. Towards the end of the Fe0.1Sc0.9N film growth, the spotty patterns transform into even spottier, but also ring-like indicating a polycrystalline behavior. Superconducting quantum interference device magnetic measurements show a ferromagnetic to paramagnetic transition of TC ˜ 370 – 380 K. We calculated a magnetic moment per atom of μ(Fe0.1Sc0.9N) = 0.037 Bohr magneton/ Mn-atom. Based on the carrier concentration measurements (nS(Fe0.1Sc0.9N) = 2.086 × 1019 /cm3), we find that iron behaves as an acceptor. Comparisons are made with similar MnScN (001)/ScN(001)/MgO(001) system.
The Interplay of Nanocontact and Electrical Properties of ZnO and InP Nanowires and Polyaniline Nanofibers
Authors: Lin Yen-Fu , Jian Wen-Bin 
Published: February 2010

AbstractThe interface problems in nanomaterial based electronics play important roles. We have learned that the nanocontact, due to its reduced contact area, could give a high electrical contact resistance and a nonlinear current-voltage behavior though the specific contact resistance is in the same order of magnitude as that of macroscopic contacts. Through the current-voltage and temperature behaviors, the nanocontact properties could be categorized into Ohmic and Schottky types. The electrical properties of the nanowire based two-probe devices could be rationalized as two Ohmic contacts, one Ohmic and one Schottky contacts, and two back-to-back Schottky contacts. Moreover, the nanocontact could be treated as a one-dimensional disordered electron system for further studies. After the intrinsic nanowire and contact resistances are separated from each other, the electron transport and the carrier concentration of native doping in ZnO and InP nanowires can be determined. The nanowires are determined to have low carrier concentrations, implying a high sensitivity to light and gas. The contact and nanowire dominated two-probe devices are exposed to light and gas to identify the contact effects. In addition to the inorganic nanowires, the organic nanomaterials, the HCl-doped polyaniline nanofibers, can be analyzed by using the same approach. The dielectrophoresis technique is implemented to position nanofibers into an electron-beam lithographically patterned nanogap. To shine the electron-beam on contact areas, the organic/inorganic nanocontact resistance is reduced so as to probe the intrinsic electrical property of a single polyaniline nanofiber.
Growing Zn0.90Co0.10O Diluted Magnetic Semiconductors by r. f. Sputtering System
Authors: Can Musa Mutlu , Firat Tezer , Özcan Şadan 
Published: February 2010

AbstractZn0.90Co0.10O particles, synthesized by mechanical milling and thermal treatment, were pressed at 25 tons to form a 2” target for a radio frequency (r. f.) magnetron sputtering system. Using this target, thin films were deposited on (0001) oriented sapphire (α-Al2O3) substrates under 30W, 60W and 120W r. f. powers. Structural analyses of these films were done with X-Ray Diffractometer (XRD), Energy Dispersive X-Ray Spectrometry (EDS), X-Ray Photo Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The ZnO films were deposited with (0002) preferred direction, which was coherent to (0001) ordered α-Al2O3. Impurity phases, such as Co clusters, CoO and Co3O4, were not detected with the surface analyses of Zn0.90Co0.10O thin films. Substituted Co atoms in the host ZnO matrix were identified by the binding energy peak of Co2p3/2, 781.3±0.4eV, and the energy difference of ∼15.61±0.03eV between Co2p1/2 and Co2p3/2. These results also proved that there were no Co clusters or Co3O4 phases in the lattice. Homogeneity of Co atoms in the lattice was shown by EDS spectra. It was understood that the higher r. f. power caused the more homogeneous distribution of Co and Zn atoms in thin films. Distributions of Co and Zn on the film surface, deposited under 120W, were found as 8.1±0.1% (normalized atomic ratio) and 91.7±0.7% (normalized atomic ratio), respectively, and the surface roughness of thin film was demonstrated by AFM figures as 14.2±0.1nm.
Effects of Growth Parameters on Surface-morphological, Structural, Electrical and Optical Properties of AZO Films by RF Magnetron Sputtering
Authors: Kuo Shou-Yi , Lin Wei-Ting , Chang Liann-Be , Jeng Ming-Jer , Lu Yong-Tian , Hu Sung-Cheng 
Published: February 2010

Abstract500 nm-thick aluminum-doped zinc oxide (ZnO:Al) thin film is usually used as a front transparent conductive oxide (TCO) contact on photovoltaic devices, and for this application is often deposited by a reactive radio-frequency (r.f.) magnetron sputtering system from a ceramic target. This work reports on the preparation and characterization of AZO thin films on Corning 1737 glass substrates grown by reactive r.f.-magnetron sputtering from a ZnO ceramic target with 2 wt% Al content. It was found that the growth parameters, such as chamber pressure, working power, and deposition temperature, have significant influences on the properties of AZO films. According to the experimental results: (1) Films were polycrystalline showing a strong preferred c-axis orientation. (2) With increasing working power, the resistivity decreased, and mobility and the carrier concentration increased. (3) Lower deposition temperature leads to a decrease in resistivity, with 2.5×10-4 Ω-cm representing the lowest resistivity reached.
Nanoscale Modification of Graphene Transport Properties by Ion Irradiation
Authors: Giannazzo Filippo , Sonde Sushant , Raineri Vito , Rimini Emanuele 
Published: February 2010

AbstractSingle layers of graphene (SLG) mechanically exfoliated from highly oriented pyrolytic graphite and deposited on SiO2/Si were irradiated with C+ ions at different fluences (from 1013 to 1014 cm-2), in order to modify the transport properties in controlled way. Using a method based on scanning probe microscopy, local measurements of the electron mean free path (l) have been carried out both on pristine and ion irradiated SLG. A lateral inhomogeneity of l was found in both cases, with an increasing spread in the distribution of l for larger fluences. Before irradiation, the spread was explained by the inhomogeneous distribution of charged impurities on SLG surface and/or at the interface with SiO2. After irradiation, lattice vacancies cause a local reduction of l in the damaged regions.
Boron Doping in Hot Filament MCD and NCD Diamond Films
Authors: Zimmer Jerry , Hantschel Thomas , Chandler Gerry , Vandervorst Wilfried , Peralta Maria 
Published: February 2010

AbstractConductive diamond films are essential for electronic applications of diamond but there is still a poor understanding of the effects that growth conditions, grain size and film thickness have on the ultimate conductivity of the film. One of the unique advantages of hot filament diamond is the ability to grow both MCD and NCD films to moderate thicknesses over large areas with little or no change in morphological characteristics such as grain size. In addition the grain size of the film can be altered without the necessity of adding additional gases to the process or unduly increasing the carbon to hydrogen ratio. This gives us an opportunity to investigate electrical conductivity as a function of grain size and thickness within a simple methane, hydrogen, and boron chemical environment over areas which are large enough to support significant production levels of MEMS and other diamond based electronics. In this study the boron source was selected to be trimethyl boron gas to avoid any source of oxygen which could alter the growth conditions and to guarantee that any byproducts of the dopant would be primarily methyl based. The films were grown to various thicknesses up to 5 micrometers and grain sizes from NCD to full MCD at all thicknesses. This paper explores the effects of both grain size and film thickness on the electrical conductivity of the film as well as the absolute doping levels within the film.
The Outlook for Diamond in Raman Laser Applications
Authors: Mildren Richard Paul 
Published: February 2010

AbstractEfficient and practical Raman lasers based on single crystal diamond are now realizable owing to the availability of optical quality crystals grown by chemical vapour deposition. In this paper, the performance characteristics of diamond Raman lasers is summarized and the results compared to other materials. The outlook for diamond Raman lasers is discussed and key challenges for material development highlighted.
Effect of Substitutional or Chemisorbed Nitrogen on the Diamond (100) Growth Process
Authors: Larsson Karin 
Published: February 2010

AbstractThe present paper outlines the energetic and kinetic effect by substitutional N, or by coadsorbed NHx (x =1, 2), on one of the key growth steps in the CVD growth mechanism of diamond (100); H abstraction by gaseous H radical species from the (100) surface plane. Theoretical calculations were performed based on Density Functional Theory under periodic boundary conditions. Substitutionally positioned N was shown to have a large effect on the H abstraction process. The H abstraction energy from the diamond surface was greatly improved with N positioned in C layer 2. In order to outline the effect by N on the growth rate, the barriers of energies were calculated. The barrier of abstraction was shown to substantially decrease with N substitutionally positioned in the second C layer, leading to an improvement of the abstraction reaction rate by approximately a factor of 3.
Surface potential of functionalised nanodiamond layers
Authors: Kratochvílová Irena , Taylor Andrew , Fendrych Frantisek , Kovalenko Alexander , Nesládek Milos 
Published: February 2010

AbstractCarbon nanomaterials especially ultrananocrystalline diamond and nanocrystalline diamond films have attracted more and more interest due to their unique electrical, optical and mechanical properties, which make them widely used for different applications (e.g. MEMS devices, lateral field emission diodes, biosensors and thermoelectrics). Nanocrystalline diamond can also offer novel advantages for drug delivery development. Recent studies have begun to use nanocrystalline diamond for in-vivo molecular imaging and bio-labeling. To enable grafting of complex bio-molecules (e.g. DNA) the surface of ND requires specific fictionalization (e.g. H, OH, COOH & NH2). Due to the surface dipoles of functionalised nanodiamond band bending at the surface can be easily induced and from the measured band bending we can deduce the type of the fictionalization on the surface. The surface potential of H-terminated and OH terminated nanodiamond layers was investigated by Kelvin probe microscope. From the change of the surface potential value (as the departure of the material surface from the state of electrical neutrality is reflected in the energy band bending) the work function of the H-terminated nanodiamond layer was established to be lower than OH-terminated nanodiamond layer. The surface potential difference can be explained by the surface dipole induced by the electro-negativity difference between the termination atoms.
Deep UV Photodetectors fabricated from CVD Single Crystal Diamond
Authors: Bevilacqua Mose , Jackman Richard B. 
Published: February 2010

AbstractDeep UV detection using a single crystal diamond (SCD) substrate without a homoepitaxial layer has been demonstrated using a defect passivation treatment. Despite evidence of surface damage on the SCD, the treatments lead to highly effective photoconductive devices, displaying six-orders of discrimination between deep UV and visible light and a responsivity as high as 100A/W, equivalent to an external quantum efficiency of 700, similar to the best values for devices based on high quality homoepitaxial layers. Impedance spectroscopic investigations suggest that the treatment used reduces the impact of less resistive surface material, most likely defects left from substrate polishing.
Diamond Photodiodes for X-ray Applications
Authors: Smedley John , Keister Jeffrey W. , Muller Erik M. , Jordan-Sweet Jean , Bohon Jen , Distel James , Dong Bin 
Published: February 2010

AbstractSingle crystal high purity CVD diamonds have been metallized and calibrated as photodiodes at the National Synchrotron Light Source (NSLS). Current mode responsivity measurements have been made over a wide range (0.2-28 keV) of photon energies across several beamlines. Linear response has been achieved over ten orders of magnitude of incident flux, along with uniform spatial response. A simple model of responsivity has been used to describe the results, yielding a value of 13.3±0.5 eV for the mean pair creation energy. The responsivity vs. photon energy data show a dip for photon energies near the carbon edge (284 eV), indicating incomplete charge collection for carriers created less than one micron from the metallized layer.
Electrospray Deposition of Diamond Nanoparticle Nucleation Layers for Subsequent CVD Diamond Growth
Authors: Fox Oliver J.L. , Holloway James O.P. , Fuge Gareth M. , May Paul W. , Ashfold Mike N.R. 
Published: February 2010

AbstractNucleation is the rate-determining step in the initial stages of most chemical vapour deposition processes. In order to achieve uniform deposition of diamond thin films it is necessary to seed non-diamond substrates. Here we discuss a simple electrospray deposition technique for application of 5 nm diamond seed particles onto substrates of various sizes. The influence of selected parameters, such as experimental spatial arrangement and colloidal properties, are analysed in optimizing the method by optical and electron microscopy, both before and after nanocrystalline diamond deposition on the seed layer. The advantages and limitations of the electrospray method are highlighted in relation to other commonly exploited nucleation techniques.
Hydrogen Incorporation in MPCVD Nanocrystalline Diamond Films During the Deposition Process
Authors: Ballutaud Dominique , Pinault Marie-Amandine , Jomard François , Lusson Alain , Saada Samuel 
Published: February 2010

AbstractHydrogen incorporation is studied in two Microwave Plasma CVD nanocrystalline diamond films deposited with prolongated BIAS or not during the growth step. The hydrogen content and bonding forms are analysed by Secondary Ion Mass Spectrometry, Raman and Fourier Transformer Infrared Spectroscopy. Our results show a high hydrogen concentration up to 3.1021 cm-1, as expected in nanocrystalline diamond, and in good agreement with the sp2 phase rate measured by Raman spectroscopy . The FTIR spectra exhibit two sharp peaks at 2850 and 2920 cm-1 and show that a fraction of hydrogen is bonded to sp3 CH2 groups. Hydrogen desorption experiments are performed to analyse the local structure modification of the diamond films.
Development of Diamond-Based X-ray Detection for High Flux Beamline Diagnostics
Authors: Bohon Jen , Smedley John , Muller Erik M. , Keister Jeffrey W. 
Published: February 2010

AbstractHigh quality single crystal and polycrystalline CVD diamond detectors with platinum contacts have been tested at the white beam X28C beamline at the National Synchrotron Light Source under high-flux conditions. The voltage dependence of these devices has been measured under DC and pulsed-bias conditions, establishing the presence or absence of photoconductive gain in each device. Linear response has been achieved over eleven orders of magnitude when combined with previous low flux studies. Temporal measurements with single crystal diamond detectors have resolved the ns scale pulse structure of the NSLS.
Transitions of Boron Carbide to B-C-N Thin Film
Authors: Bao Ruqiang , Yan Zijie , Chrisey Douglas B. 
Published: February 2010

AbstractBoron carbon nitride (B-C-N) thin films are attractive due to their potential as hard coatings and as semiconductors with varying band gap. Both B-C-N (BC0.24N0.24) thin films and boron carbide (B4C) thin films were deposited by radio-frequency magnetron sputtering at room temperature. Also, the transition of boron carbide to B-C-N was studied by bombarding the boron carbide thin film by ∼1 uA/cm2 4 keV N+ ions. The results show that the UV-Vis transmittance of B-C-N thin films is better than that of amorphous boron carbide and both B-C and B-N bonds exist in our B-C-N thin films. The nitrogen in our B-C-N thin films bonded with boron causes the XPS B 1s core level to shift 2 eV from that in the B4C boron carbide thin film. Ion bombardment shows that the N+ ion primarily reacts with boron to form B-N and this reaction causes the environmental change of carbon in the thin film and then the XPS C 1s core level to shift to 283.5 eV from 282.8 eV.
Electrical Resistance of Single-Wall Carbon Nanotubes with Determined Chiral Indices
Authors: Lin Letian , Qin Lu-Chang , Washburn Sean , Paulson Scott 
Published: February 2010

AbstractThe properties of a carbon nanotube (CNT), in particular a single-wall carbon nanotube (SWNT), are highly sensitive to the atomic structure of the nanotube described by its chirality (chiral indices). We have grown isolated SWNTs on a silicon substrate using chemical vapor deposition (CVD) and patterned sub-micron probes using electron beam lithography. The SWNT was exposed by etching the underlying substrate for transmission electron microscope (TEM) imaging and diffraction studies. For each individual SWNT, its electrical resistance was measured by the four-probe method at room temperature and the chiral indices of the same SWNT were determined by nano-beam electron diffraction. The contact resistances were reduced by annealing to typically 3-5 kΩ. We have measured the I-V curve and determined the chiral indices of each nanotube individually from four SWNTs selected randomly – two are metallic and two are semiconducting. We will present the electrical resistances in correlation with the carbon nanotube diameter as well as the band gap calculated from the determined chiral indices for the semiconducting carbon nanotubes. These experimental results are also discussed in connection with theoretical estimations.
In-situ TEM-STM Observations of SWCNT Ropes/tubular Transformations
Authors: Solá Franscisco , Lebrón-Colón Marisabel , Ferreira F. , Fonseca Luis F. , Meador Michael A. , Marín Carlos J. 
Published: February 2010

AbstractSingle-walled carbon nanotubes (SWCNTs) prepared by the HiPco process were purified using a modified gas phase purification technique. A TEM-STM holder was used to study the morphological changes of SWCNT ropes as a function of applied voltage. Kink formation, buckling behavior, tubular transformation and eventual breakdown of the system were observed. The tubular formation was attributed to a transformation from SWCNT ropes to multi-walled carbon nanotube (MWCNT) structures. It is likely mediated by the patching and tearing mechanism which is promoted primarily by the mobile vacancies generated due to current-induced heating and, to some extent, by electron irradiation.
On the Relation of Mechanical Deformation and Electrical Properties of BN Nanotubes
Authors: Ghassemi Hessam , Lee Chee Huei , Yap Yoke Khin , Shahbazian Yassar Reza 
Published: February 2010

AbstractUsing a novel in-situ scanning tunneling microcopy integrated into a 200Kv transmission electron microscopy, we have shown that boron nitride nanotubes (BNNTs) posses remarkable flexibility and convert from insulator to semi-conductor upon bending. To measure the electrical properties, the BNNT was bent between two gold contacts constructing a metal-semiconductor-metal circuit. The resistivity of the BNNT under bending condition was measured to be ∼460 MΩ from the experimentally recorded current-voltage data. Our finding suggests that mechanical straining can improve the electrical transport in BN nanotubes via reducing the band gap.