bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA Gating effect from single layer graphene
Authors: Lin Jian , Teweldebrhan Desalegne , Ashraf Khalid , Liu Guanxiong , Jing Xiaoye , Yan Zhong , Ozkan Mihrimah , Lake Roger K. , Balandin Alexander A. , Ozkan Cengiz S. 
Published: September 2011

ABSTRACTIn this letter, single stranded Deoxyribonucleic Acids (ssDNA) are found to act as negative potential gating agents that increase the hole density in single layer graphene (SLG). Current-voltage measurement of the hybrid ssDNA/graphene system indicates a shift in the Dirac point and “intrinsic” conductance after ssDNA is patterned. The effect of ssDNA is to increase the hole density in the graphene layer, which is calculated to be on the order of 1.8×1012 cm-2. This increased density is consistent with the Raman frequency shifts in the G-peak and 2D band positions and the corresponding changes in the G-peak full-width half maximum. This patterning of DNA on graphene layers could provide new avenues to modulate their electrical properties and for novel electronic devices.
The Dynamics of Formation of Graphane-like Fluorinated Graphene Membranes (Fluorographene): A Reactive Molecular Dynamics Study
Authors: Santos Ricardo P. B. , Autreto Pedro A. S. , Legoas Sergio B. , Galvao Douglas S. 
Published: September 2011

ABSTRACTUsing fully reactive molecular dynamics methodologies we investigated the structural and dynamical aspects of the fluorination mechanism leading to fluorographene formation from graphene membranes. Fluorination tends to produce significant defective areas on the membranes with variation on the typical carbon-carbon distances, sometimes with the presence of large holes due to carbon losses. The results obtained in our simulations are in good agreement with the broad distribution of values for the lattice parameter experimentally observed. We have also investigated mixed atmospheres composed by H and F atoms. When H is present in small quantities an expressive reduction on the rate of incorporation of fluorine was observed. On the other hand when fluorine atoms are present in small quantities in a hydrogen atmosphere, they induce an increasing on the hydrogen incorporation and the formation of locally self-organized structure of adsorbed H and F atoms.
Stable superconducting niobium ultrathin films
Authors: Delacour Cécile , Ortega Luc , Pannetier Bernard , Bouchiat Vincent 
Published: September 2011

ABSTRACTWe report on a combined structural and electronic analysis of niobium ultrathin films (from 2.5 to 10 nm) epitaxially grown in ultra-high vacuum on atomically flat sapphire wafers. We demonstrate a structural transition in the early stages of Nb growth, which coincides with the onset of a superconducting-metallic transition (SMT). The SMT takes place on a very narrow thickness range (1 ML). The thinnest superconducting sample (3 nm/ 9ML) has an offset critical temperature above 4.2K and allows to be processed by standard nanofabrication techniques to generate air and time stable superconducting nanostructures.
Langmuir-Blodgett Assembly of Soft Carbon Sheets
Authors: Cote Laura J. , Kim Jaemyung , Huang Jiaxing 
Published: September 2011

AbstractGraphene oxide sheets have recently gained immense interest as a building block for graphene based materials and devices. Rapid developments have been made in the chemistry and applications of GO. However, assembly, too, plays a critical role in the final properties of bulk graphene based materials as it determines the microstructures of the 2D sheets. There is thus a pressing need for controllable assembly strategies. Based on the recent identification of the pH dependent surfactant-like behavior of GO sheets, we are now able to control the tiling morphologies of such sheets to produce thin films with either wrinkled or overlapped types of microstructures. This allows for the deconvolution of the effects of these two basic morphological features in the electrical and optical properties of the resulting thin films, providing a well-defined example of the processing-microstructure-properties relationship for this unique soft material building block.
Cost Effective Fabrication of Wafer Scale Nanoholes for Solar Cells Application
Authors: Zhao Y Q , Leung K K , Surya C , Feng C K , Chen Y F , Chen D M , Shen H , Zhang B J 
Published: September 2011

ABSTRACTWe report fabrication of random nanometer-scale radial p-n junction solar cells (SCs). Nanoholes were fabricated on the Si wafer by combining silver film annealing and metal catalyzed electrochemical etching (MECC) of the material. The dimension of the holes can be adjusted by varying the annealing conditions and the thickness of the Ag film. Systematic investigations on the effects of the nanohole size and the doping conditions on the cell efficiency were performed.
Aerosol technology and Si nano-composite electrode assembly for Li-ion batteries
Authors: Munao David , Valvo Mario , van Erven Jan , Garcia-Tamayo Esteban , Kelder Erik 
Published: September 2011

ABSTRACTIn this work novel approaches to fabricate silicon-based electrodes are shown. Starting from silicon nano-particles it is possible to create nano-structured porous thin films. Both the synthesis of the Si nano-particles and the electrode assembly are performed via aerosol routes. This guarantees a very good control on the particle size and the particle size distribution, on the purity of the product and on the morphology and texture of the deposited layers. Particles are produced via Laser assisted Chemical Vapor Pyrolysis whereas electrode thin layers are deposited via Electro Spray method. The range of particle sizes can be tailored according to the selected application. Here, particles of a mean size of about 10 nm have been synthesized. Since Si is well known to forms highly lithiated intermetallic compounds [1], it is regarded as one of the most promising material for energy storage [2], especially looking at high energy density applications, such as hybrid/electric vehicle traction. In this work its promising performance are presented. The role of the additives in the composite formulation is also taken into account for a more clear understanding of the capacity fading mechanism of such electrodes.
Nano-engineering with a focused helium ion beam
Authors: Maas Diederik J. , van der Drift Emile W. , Veldhoven Emile van , Meessen Jeroen , Rudneva Maria , Alkemade Paul F. A. 
Published: September 2011

ABSTRACTAlthough Helium Ion Microscopy (HIM) was introduced only a few years ago, many new application fields are budding. The connecting factor between these novel applications is the unique interaction of the primary helium ion beam with the sample material at and just below its surface. In particular, the HIM secondary electron (SE) signal stems from an area that is very well localized around the point of incidence of the primary beam. This makes the HIM well-suited for both high-resolution imaging as well as high resolution nanofabrication. Another advantage in nanofabrication is the low ion backscattering fraction, leading to a weak proximity effect. The lack of a quantitative materials analysis mode (like EDX in Scanning Electron Microscopy, SEM) and a relatively low beam current as compared to the SEM and the Gallium Focused Ion Beam are the present drawbacks of the HIM.
Silicon Nanocavity Based Light Sources
Authors: Gong Yiyang , Ishikawa Satoshi , Cheng Szu-Lin , Nishi Yoshio , Yerci Selcuk , Li Rui , Negro Luca Dal , Vuckovic Jelena 
Published: September 2011

ABSTRACTWe develop Si-based nano-photonic devices for the control of light at the nano-scales. We design high quality (Q) factor photonic crystal nanobeam cavities for a variety of Si compatible materials with low index, such as silicon rich oxide and silicon nitride, all with Q > 9,000 and small mode volumes. We apply these cavity designs to active materials such as Sinanocrystal doped silicon oxide and Er doped silicon nitride. By placing emitters in these cavities, we demonstrate that the cavity enhances emission processes. We show that the free carrier absorption process is greatly enhanced in the nanobeam cavities at both room and cryogenic temperatures. In addition, we demonstrate that nanobeam cavities made of Er-doped amorphous silicon nitride have enhanced absorption and gain characteristics compared to earlier designs that included silicon in the cavity. Because of the reduced losses, we observe linewidth narrowing and material transparency at both room temperature and cryogenic temperatures.
Formation of ultra-shallow Ohmic contacts on n-Ge by Sb delta-doping
Authors: Sawano K. , Hoshi Y. , Kasahara K. , Yamane K. , Hamaya K. , Miyao M. , Shiraki Y. 
Published: September 2011

ABSTRACTWe demonstrate low-resistivity Ohmic contacts for n-Ge with ultra-shallow junction. Using the impurity δ-doping techniques with Ge homoepitaxy on Ge(111) below 400 ºC, we can achieve a very abrupt doping profile within a nanometer-scale width. By introducing the δ-doping to atomically controlled metal/Ge contacts, the current-voltage characteristics clearly show Ohmic conductions owing to the effective tunneling through the Schottky barrier. This approach is promising for a formation technology of ultra-shallow source/drain contacts for scaled Ge devices.
Structural Properties of Iron Nitride on Cu(100): an Ab-initio Molecular Dynamics study
Authors: Heryadi Dodi , Schwingenschlögl Udo 
Published: September 2011

ABSTRACTDue to their potential applications in magnetic storage devices, iron nitrides have been a subject of numerous experimental and theoretical investigations. Thin films of iron nitride have been successfully grown on different substrates. To study the structural properties of a single monolayer film of FeN we have performed an ab-initio molecular dynamics simulation of its formation on a Cu(100) substrate. The iron nitride layer formed in our simulation shows a p4gm(2x2) reconstructed surface, in agreement with experimental results. In addition to its structural properties, we are also able to determine the magnetization of this thin film. Our results show that one monolayer of iron nitride on Cu(100) is ferromagnetic with a magnetic moment of 1.67μB.
Morphology and Magneto-optical Properties of Amorphous AlN Films Doped with Nickel
Authors: Jadwisienczak W. M. , Tanaka H. , Chen G. , Kordesch M. , Khan A. 
Published: September 2011

ABSTRACTStructural and magneto-optical properties of Ni-doped amorphous AlN layers (a-AlN) deposited by radio frequency (rf) sputtering on Silicon (001) substrates were investigated. The as-grown material exhibits weak ferromagnetic behavior as evidenced by the magneto-optic Kerr effect (MOKE) measurement with Kerr rotation less than 100 μrad at room temperature regardless of the Ni fraction. The samples with a Ni concentration below 10 at.% show a weak but monotonically increasing MOKE signal with post-growth annealing temperature. A hundred-fold increase in the Kerr rotation value was observed for samples with Ni content exceeding 20 at.% after thermal annealing at 450°C in nitrogen; and the Kerr rotation value abruptly decreases above that temperature. The morphology of as-grown and annealed a-AlN:Ni films were characterized by small angle x-ray scattering and transmission electron microscopy. It was found that the as-deposited film contains nano-particles of different sizes with average diameters less than 30 nm. The size distribution of nano-particles in the thermally annealed a-AlN:Ni was studied as a function of annealing time and temperature. The results correlate well with those obtained from the MOKE measurements.
In-situ Observations of Restructuring Carbon Nanotubes via Low-voltage Aberration-corrected Transmission Electron Microscopy
Authors: Börrnert Felix , Bachmatiuk Alicja , Gorantla Sandeep , Warner Jamie H. , Büchner Bernd , Rümmeli Mark H. 
Published: September 2011

ABSTRACTThe molecular structure and dynamics of carbon nanostructures is much discussed throughout the literature, mostly from the theoretical side because of a lack of suitable experimental techniques to adequately engage the problem. A technique that has recently become available is low-voltage aberration-corrected transmission electron microscopy. It is a valuable tool with which to directly observe the atomic structure and dynamics of the specimen in situ. Time series aberration-corrected low-voltage transmission electron microscopy is used to study the dynamics of single-wall carbon nanotubes in situ. We confirm experimentally previous theoretical predictions for the agglomeration of adatoms forming protrusions and subsequent removal. A model is proposed how lattice reconstruction sites spread. In addition, the complete healing of a multi-vacancy consisting of ca. 20 missing atoms in a nanotube wall is followed.
Glancing Angle Deposited Platinum Nanorod Arrays for Oxygen Reduction Reaction
Authors: Khudhayer Wisam J. , Kariuki Nancy , Myers Deborah , Shaikh Ali , Karabacak Tansel 
Published: September 2011

ABSTRACTIn this work, we investigated the electrocatalytic oxygen reduction reaction (ORR) activity of vertically aligned, single-layer, carbon-free, and single crystal Pt nanorod arrays utilizing cyclic voltammetry (CV) and rotating-disk electrode (RDE) techniques. A glancing angle deposition (GLAD) technique was used to fabricate 200 nm long Pt nanorods, which corresponds to Pt loading of 0.16 mg/cm2, on glassy carbon (GC) electrode at a glancing angle of 85° as measured from the substrate normal. An electrode comprised of conventional carbon-supported Pt nanoparticles (Pt/C) was also prepared for comparison with the electrocatalytic ORR activity and stability of Pt nanorods. CV results showed that the Pt nanorod electrocatalyst exhibits a more positive oxide reduction peak potential compared to Pt/C, indicating that GLAD Pt nanorods are less oxophilic. In addition, a series of CV cycles in acidic electrolyte revealed that Pt nanorods are significantly more stable against electrochemically-active surface area loss than Pt/C. Moreover, room temperature RDE results demonstrated that GLAD Pt nanorods exhibit higher area-specific ORR activity than Pt/C. The enhanced electrocatalytic ORR activity of Pt nanorods is attributed to their larger crystallite size, single-crystal property, and the dominance of (110) crystal planes on the large surface area nanorods sidewalls, which has been found to be the most active plane for ORR. However, the Pt nanorods showed lower mass specific activity than the Pt/C electrocatalyst due to the large diameter of the Pt nanorods.
Elimination of Degenerate Epitaxy in the Growth of High Quality B12As2 Single Crystalline Epitaxial Films
Authors: Zhang Yu , Chen Hui , Dudley Michael , Zhang Yi , Edgar J. H. , Gong Yinyan , Bakalova Silvia , Kuball Martin , Zhang Lihua , Su Dong , Zhu Yimei 
Published: September 2011

ABSTRACTElimination of degenerate epitaxy in the growth of icosahedral boron arsenide (B12As2, abbreviated as IBA) was achieved on m-plane 15R-SiC substrates and 4H-SiC substrates intentionally misoriented by 7 degrees from (0001) towards [1-100]. Synchrotron white beam x-ray topography (SWBXT) revealed that only single orientation IBA was present in the epitaxial layers demonstrating the absence of twin variants which dominantly constitute the effects of degenerate epitaxy. Additionally, low asterism in the IBA diffraction spots compared to those grown on other SiC substrates indicates a superior film quality. Cross-sectional high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) both confirmed the absence of twins in the IBA films and their high quality. The ease of nucleation on the ordered step structures present on these unique substrates overrides symmetry considerations that drive degenerate epitaxy and dominates the nucleation process of the IBA.
Facile Synthesis of Pure Boron Nanotubes and Nanofibers
Authors: Liu Jinwen , Iqbal Zafar 
Published: September 2011

ABSTRACTA facile and scalable chemical vapor deposition (CVD) process in flowing argon using a solid instead of a reactive gaseous boron precursor has been carried out to synthesize crystalline boron nanostructures comprising of relatively straight boron nanotubes (BNTs) and nanofibers (BNFs). The synthesis involves the use of solid magnesium boride as the boron and magnesium catalyst precursor, nickel boride as co-catalyst, and MCM-41 zeolite as the growth template. The BNTs and BNFs produced have a narrow distribution of diameters between about 10 nm to 20 nm and lengths from about 500 nm to above 1 μm. Scanning and transmission electron microscope (SEM and TEM) imaging together with electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) have been conducted to characterize the structure, morphology and growth mechanism of these novel nanostructures. High resolution TEM imaging has been used to identify BNTs and BNFs in the nanostructures synthesized.
Growth and Field Emission Properties of Boron Nitride Island Films by Low-energy Ion-assisted Deposition
Authors: Teii K. , Yang J. H. C. , Yamao R. , Matsumoto S. 
Published: September 2011

ABSTRACTWe report the growth and field emission properties of boron nitride (BN) island films by chemical vapor deposition in inductively coupled plasma. Fine-grained island films with large surface roughness can be grown for initial sp2-bonded BN and subsequent cubic BN (cBN) phases by using low-energy (~20 eV) ion bombardment. Ultraviolet photoelectron spectroscopy indicates that the electron affinity is as low as 0.3 eV for both sp2-bonded BN and cBN phases. The evolution of cBN islands reduces the turn-on field down to around 9 V/μm and increases the current density up to 10-4 A/cm2. The surface potential barrier height is estimated to be about 3.4 eV for emission from the Fermi level.
Deposition and Etching of Conformal Boron Films for Neutron Detector Applications
Authors: LiCausi Nicholas , Clinton Justin , Danon Yaron , Lu James J.-Q. , Bhat Ishwara B. 
Published: September 2011

ABSTRACTIn this work, the deposition of boron using low pressure chemical vapor deposition (LPCVD) has been investigated on planar and deep reactive ion etched (DRIE) Si substrates. Deposition rate and conformal coverage have been studied. Additional studies of “dry” RIE etching and “wet” chemical etching of the deposited boron films are presented. Deposition rates as high as 1 μm/hr and conformal coverage ratios of ~80% have been achieved. Etching rates for various methods studied range widely from 0.35 μm/hr to 1.2 μm/min.
Towards Radiolabeled G∧C Module for Cellular Imaging of Bioactive Rosette Nanotubes
Authors: Alsbaiee Alaaeddin , St. Jules Mustapha , Beingessner Rachel L. , Fenniri Hicham 
Published: September 2011

ABSTRACTRosette nanotubes (RNTs) are obtained through the self-organization of biologically inspired self-complementary guanine-cytosine modules (G∧C motif) under physiological conditions. These architectures can express bioactive molecules on their surface by functionalizing the G∧C motif prior to self-assembly. As a result, RNTs are promising drug delivery vehicles for the treatment of diseases such as cancer and inflammatory disorders. Towards these studies, we have explored the toxicity and immunological response of RNTs and are now focused on understanding their cellular uptake, biological distribution and kinetics in vivo. For these investigations, we need to construct a RNT labeled with a radionuclide that can be followed in vivo by SPECT (single photon emission computed tomography) imaging. In this proceeding, we describe a twin G∧C motif that is functionalized with mercaptoacetyl triglycine (MAG3). This is a well known ligand which is able to form a stable chelate with the radionuclides 99mTc or 186/188Re. In order to develop the chemistry for this radiolabeling strategy for the RNTs, we demonstrate the chelation of the MAG3 functionalized twin-G∧C motif with cold rhenium and investigate the self-assembly properties of the complex into RNTs under aqueous conditions.
Electrostatic and Steric Effect of Peptides Functionalized on Self-Assembled Rosette Nanotubes
Authors: El-Bakkari Mounir , Beingessner Rachel L. , Alshamsan Aws , Cho Jae-Young , Fenniri Hicham 
Published: September 2011

ABSTRACTDiscrete nanoscale tubular architectures have received significant attention during the past decade because of their potential role in electronic and photonic devices, sensors, liquid crystals, artificial channel systems and biomedical engineering [1-2]. Our research group has reported the synthesis and characterization of the bicyclic G∧C motif, a self complementary DNA base analogue, which undergoes hierarchical self-assembly to form Rosette Nanotubes (RNTs) [3]. The stability of this system depends however, on functional group density (sterics) and net charge (electrostatics) on the RNT surface [5c]. To this end, we have synthesized several G∧C modules bearing oligopeptides with different lengths and net charge and investigated their self-assembling properties.
Characterization of bismuth telluride aerogels for thermoelectric applications
Authors: Dong Wenting , Rhine Wendell , Caggiano Greg , Evans Owen R. , Gould George , White John , Sharp Jeff , Gilbert Pat , Ganguly Shreyashi , Brock Stephanie L. 
Published: September 2011

ABSTRACTRefrigeration, air conditioning, and other cooling requirements in buildings, industry, and transportation sectors account for about 10 quads of U.S. primary energy consumption. Therefore, advanced technologies for space cooling in buildings and vehicles – as well as for refrigeration in residential, commercial, and industrial applications – that are more energy efficient, avoid net direct greenhouse gas emissions, reduce lifecycle costs, and can impact large markets are needed. Although current technologies are reaching their efficiency limits, thermoelectric (TE) materials can be used for cooling applications and have potential for significant improvements. Compared to traditional bulk phase TE materials, literature results suggest that nanometer-scale materials allow additional opportunities to improve the efficiency of TE materials. Aerogels are one type of nano-material that offers opportunities to increase the efficiency of TE materials by controlling particle size, particle composition and by reducing the thermal conductivity. Bismuth telluride (Bi2Te3) is the most studied TE material and our objective was to produce bismuth telluride aerogels with controlled microstructures and thermal conductivities to increase the TE figure of merit. Aspen Aerogels developed a novel synthesis method to prepare Bi2Te3 aerogels using the principles of colloidal chemistry and sol-gel chemistry. The reaction conditions were investigated and optimized so that gels could be obtained at low reaction temperatures. The gels were aged and dried using supercritical CO2. The aerogels were characterized by BET, XRD, and SEM. The best aerogels were hot pressed and Seebeck coefficients were determined. The synthetic approach developed and the properties of the aerogels will be presented and compared with Bi2Te3 aerogels and materials prepared by other methods.
Investigations on Plasmonic Modes of Noble Metal Nano-Disks Using High-Resolution Cathodoluminescence Imaging Spectroscopy
Authors: Kumar Anil , Fung Kin Hung , Fang Nicholas X. 
Published: September 2011

ABSTRACTIn this work, we report investigations on plasmonic nano-disks using cathodoluminescence (CL) imaging and spectroscopy. 50 nm thick gold disks fabricated using electron beam lithography were studied and several modes were identified. Detailed analysis of the modes using monochromatic imaging and CL spectra showed strong size dependence. Our investigations on these plasmonic nano-disks allow understanding of light-matter interaction at nanoscale, with several potential applications including next generation plasmonic nano-lasers.