bluuebunny/crossref_metadata_2025 huggingface dataset:
Cobalt Silicidation on Sub 100nm Hole Patterned Vertical Diode Formed by Silicon Epitaxial Growth and Its Electrical Properties
Authors: Lee Min Yong , Lee K. B. , Lee H. S. , Chae S. J. , Han I. K. , Kang H. S. , Park S. W.
Published: April 2011

Self-aligned Cobalt silicide as ohmic contact layer on sub 100 nm hole patterned Si vertical diode formed by silicon epitaxial growth (SEG) is investigated and silicon epitaxial growth of higher than 4000 Å thickness and good crystalinity for PN diode has been successfully developed. Also, electrical isolation of 100 nm pitch size between diode and diode, and removal of unreacted Co/Ti/TiN layer have been realized by dip-out process without CMP simultaneously. Through the mechanism of void formation due to the variation of Si consumption rate during silicidation at limited hole pattern dimension, critical Co and Capping Ti thickness are investigated as various hole dimensions (80∼120 nm), and then with p+ type dopant species (49BF2, 11B). The ratio of Co thickness to hole dimension demonstrates void free cobalt silcidation on various pattern sizes of silicon epitaxial growth. Silicon epitaxial growing PN diodes including void free CoSi2 show excellent electrical performance, especially lower than 10 pA reverse off leakage current.
Structure and Electrical Properties of Atomic-scale In-Bi Nanowire Arrays
Authors: Owen James Hugh Gervase , Kubo Osamu , Bowler David
Published: April 2011

The 1-nm-wide Bi nanoline has been proposed as a possible template for the growth of very-high-density arrays of atomic-scale nanowires, grown epitaxially on the technologically important Si(001) surface. Indium reacts with the Bi dimers, forming a unique zigzag atomic chain structure. Simulations of the appearance in STM of the lowest-energy isomer of this structure match experimental filled-states images. Calculation of the LDOS for the single-layer islands, finds that the nanowires are semiconducting, with a band gap smaller than that of the substrate, in good agreement with STS. A delocalised LUMO state is created, which may provide a conduction pathway along the nanowire. We have performed dual-probe STM conduction measurements along the In-Bi nanowires to test this prediction.
Infrared behavior of aluminum nanostructure sculptured thin films
Authors: Hofmann Tino , Schubert M. , Schmidt D. , Schubert E.
Published: April 2011

We report on fabrication, structural and infrared optical characterization of nanostructure aluminum sculptured thin films prepared by glancing angle deposition (GLAD) and controlled substrate motion on p-type silicon. We discuss two structures, one with plate-like and one with screw-like (chiral) morphology. While the plate-like sample possesses a metal Drude behavior in the infrared spectral range, the chiral nanowire sample behaves non-metallic and reveals a series of intriguing resonances, which are equally spaced in frequency by ∼7.5 THz. We suggest that formation of 3D nano resonator circuits consisting of inductances and capacitances has occurred within the screw-like conductive aluminum wire sample, which might be responsible for the observed resonances. We suggest conductive GLAD nanostructures in combination with Schottky diodes to facilitate active or passive THz detector and transmitter devices.
Indium-assisted Growth of Si Nanowires: Perspectives on Controlled Growth for CMOS Applications
Authors: Iacopi Francesca , Eichhammer Yann , Massy Claire , Vereecken Philippe M , Moelans Nele , Richard Olivier , Smeets Dries , Blanpain Bart , De Gendt Stefan , Heyns Marc
Published: April 2011

Semiconductor nanowires are attractive nano- building blocks for microelectronics. However, the requirements for their manufacturing and application in the microelectronics industry are very demanding. Beyond compatibility with Si technology, full control on the characteristics of the grown wires (diameter, location, crystallinity, etc..), homogeneity on wafer –scale and reproducibility are essential. In this study we review critically important challenges for a controlled process of In –mediated growth of Si nanowires. First, we stress the importance of surface type for both particle catalysts and growth substrates. Both selection and preparation of such surfaces have large impact on growth, as they influence the initiation and the driving forces for the VLS growth mechanism. Moreover, wire characteristics such as morphology, crystalline quality and growth orientation appear more difficult to control when growing from particles with sizes below 40-50nm. This limitation arises as a result of both fundamental mechanisms and more specific constrains linked to the In-Si system.

A few perspectives are given for the achievement of a controlled Si nanowire growth in a Si –technology compatible fashion.
Raman Spectroscopic Analysis of p-doped Bridged InP Nanowire
Authors: Sarkar Ataur , Islam M. Saif , Yi Sungsoo , Talin A. Alec
Published: April 2011

Raman spectroscopy was performed on magnesium (Mg) doped InP nanowires bridged between single crystal vertical silicon electrodes using a green laser (λ∼ 532 nm). First order TO-phonon and LO phonon-plasmon peaks observed at 305 cm−1 and 345 cm−1, respectively, are consistent with those for bulk single crystal InP. Misorientation of the nanowires is found to influence the TO and LO peak intensities. Bottom broadening up to ∼20 cm−1 of the TO peak due to the energy dispersion in the shifted Stokes spectrum is observed in long (∼6 μm) nanowires. Raman measurements indicated a trace of uncatalyzed InP on the insulating silicon oxide substrate and was verified through the electrical measurements of leakage currents before and after the nanowire growth. Initial investigation reveals that Raman spectroscopy can be a very useful in the study of nanowire heterostructures.
Preparation and Characterization of BN Nanotubes with Controllable Sizes by Template-aided Synthesis
Authors: Wang Yuting , Shimada Shiro , Kiyono Hajime , Yamamoto Yasunori
Published: April 2011

In this study, an efficient approach to prepare high quality BN nanotubes (BNNTs) was developed. BNNTs with specific sizes were prepared by sublimation of ammonia borane complex (BH3NH3) using two kinds of porous alumina anodic membrane template in two independently temperature controlled furnaces in a glovebox filled with N2. The BNNTs with template were nitrided at different temperatures 1300 ∼ 1700 °C in NH3. The BNNTs of 200 – 300 nm wide°60×°m long, and 70 – 80 nm wide°×40 μm long were finally collected after removal of the template by etching of with 40 wt% NaOH solution. The fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) results confirmed the formation of BN from BH3NH3. Ordered arrays of BNNTs were observed by scanning electron microscopy (SEM), and the microstructure of these BNNTs was investigated by transmission electron microscopy (TEM). It was found that the diameters of the BNNTs can be easily controlled by using templates with different pore sizes. The wall thickness of the nanotubes was increased by increasing the sublimation time or the amount of the starting BH3NH3. The crystallinity of BNNTs was improved at higher temperatures (1700 °C) in NH3.
Synthesis and Electronic Properties SWCNT Sheets
Authors: Lashmore David , White Brian , Schauer Mark , Mann Jenn
Published: April 2011

The commercial synthesis of carbon nanotube sheets will be described. This process involves the following steps: chemical vapor deposition of long CNTs from mixed hydrocarbon type fuels, creation and stabilization of the catalyst, and a large textile forming device. Movies of the growth process will be presented and described. Further the electronic properties of these textiles will be presented and discussed as: (1) A function of temperature from −4 °K to 500 °C, (2) A function frequency from 0 up to about 30 GHz and (3) In a magnetic field up to 1000 Oe. It is shown that these yarns have semiconductor properties but surprisingly exhibit apparent metallic like conduction high at high frequencies. The thermoelectric behavior of the textiles (and yarns) made of this material will be discussed as will the applications in secondary batteries. A power level of up to three watts per gram for the thermoelectric material has been demonstrated.
Ab Initio Modeling of Contact Structure Formation of Carbon Nanotubes and Its Effect on Electron Transport
Authors: Luo Weiqi , Ravichandran Karthik , Windl Wolfgang , Fonseca Leonardo R.C.
Published: April 2011

Carbon nanotube (CNT) devices are studied as a possible alternative to the current silicon based CMOS technology. The contacts between CNTs and metal electrodes in such devices exert great influence on the device performance. In this study, ab-initio temperature accelerated dy-namics are performed to study the contact formation between CNTs and Ti electrodes. Results indicate that CNTs undergo significant structural deformation, resulting in a significant decrease of the device conductance. This finding may explain the discrepancy between experimental and simulated results in molecular devices. However, more effects may need to be taken into account as we discuss for the example of the size effect of CNTs.
Chemoselective Polymers, Nanoparticles, and Nanotubes in Chemical Sensor and Preconcentrator Applications
Authors: Simonson Duane L , McGill R Andrew , Papantonakis Michael R. , Higgins Bernadette A. , Stepnowski Jennifer L.
Published: April 2011

The functionalization of polymers and nano-materials with 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) groups provides materials suitable for a variety of preconcentrator and sensor applications. These are especially useful in high vapor pressure, hydrogen-bond basic vapor collection. These specific interactions lead to high efficiency collection of basic analytes such as DMMP (organophosphonates), DNT, and TNT (nitroaromatics). The lower vapor pressure analytes such as RDX have a larger dependence on surface interactions without specific (hydrogen bond) interactions. The use of carbosilane polymers with HFIP pendant groups offers dramatic improvements over fluoropolyol (FPOL) and siloxane polymers in sensor and precon applications. The sorbent capacity and thermal stability are both dramatically improved. In this work we will demonstrate the use of Carbon Nanotube (CNT) composites with HFIP polymers as sorbent coatings and evaluate their use as SPME coatings.
Nanoprober-Based Pick-and-Place Process for Site-Specific Characterization of Individual Carbon Nanotubes
Authors: Hantschel Thomas , Ryan Peter , Palanne Saku , Richard Oliver , Arstila Kai , Verhulst Anne S. , Bender Hugo , Ke Xiaoxing , Vandervorst Wilfried
Published: April 2011

The potential use of carbon nanotubes (CNT) as interconnects requires also new characterization approaches as the existing ones are optimized for three-dimensional materials and do not work for inherently one-dimensional structures like CNTs. Therefore, we have developed a so-called pick-and-place process which allows to remove an individual CNT from a specific site and to place it at another location for further analysis. The approach is based on nanomanipulation combined with scanning electron microscopy (SEM). This paper presents the pick-and-place concept and explains the different steps required for its successful application. We further demonstrate its power by characterizing individual CNTs using transmission electron microscopy (TEM) and atomic force microscopy (AFM). The developed pick-and-place approach overcomes the challenge of site-specific analysis of CNT interconnects and strongly facilitates the routine analysis of CNTs.
Low-power and Fast-switching Organic Field-effect Transistors with Ionic Liquids
Authors: Ono S. , Seki S. , Hirahara R. , Tominari Y. , Takeya J.
Published: April 2011

We report high-mobility rubrene single-crystal field-effect transistors with ionic-liquid electrolytes used for gate dielectric layers. As the result of fast ionic diffusion to form electric double layers, their capacitances remain more than 10 μF/cm2 even at 0.1 MHz. With high carrier mobility of 1.2 cm2/Vs in the rubrene crystal, pronounced current amplification is achieved at the gate voltage of only 0.2 V, which is two orders of magnitude smaller than that necessary for organic thin-film transistors with dielectric gate insulators. The results demonstrate that the ionic-liquid/organic semiconductor interfaces are suited to realize low-power and fast-switching field-effect transistors without sacrificing carrier mobility in forming the solid/liquid interfaces.
Numerical Modeling of Electrothermal Effects in Silicon Nanowires
Authors: Boztug Cicek , Bakan Gokhan , Akbulut Mustafa , Gokirmak Ali , Silva Helena
Published: April 2011

Asymmetric melting was observed in electrically pulsed n-type (phosphorus) nanocrystalline silicon (nc-Si) wires fabricated lithographically. Scanning electron microscope (SEM) images taken from the pulsed wires showed that melting initiates from the ground terminal end of the wires instead of the center as initially expected. Asymmetry in the temperature profile is caused by heat exchanged between charge carriers and phonons when an electrical current is passed along a temperature gradient. This effect is known as Thomson effect, a thermoelectric heat transfer mechanism. One dimensional (1D) time dependent heat diffusion equation including Thomson heat term was solved to model the temperature profile on our structures. The modeling results show that Thomson effect introduces significant shifts in the temperature distribution. The effect of Thomson heat is modeled for various electrical pulse conditions and wires dimensions. Our results indicate that Thomson effect is significant in small scale electronic devices operating under high current densities.
Nano-scale Tribological Behavior of Polycrystalline Silicon Structural Films in Ambient Air
Authors: Alsem Daan Hein , van der Hulst Ruben , Stach Eric A. , Dugger Michael T. , de Hosson Jeff Th. M. , Ritchie Robert O.
Published: April 2011

Dynamic friction, wear volumes and wear morphology have been studied for sliding wear in polysilicon in ambient air at μN normal loads using on-chip micron-scale test specimens. With increasing number of wear cycles, the friction coefficients show two distinct types of behavior: (i) an increase by a factor of two and a half to a steady-state regime after peaking at three times the initial value of about 0.10 ± 0.04, with no failure after millions of cycles; (ii) an increase by a factor larger than three followed by failure after ∼105 cycles. Additionally, the average nano-scale wear coefficient sharply increased in the first ∼105 cycles up to about 10−4 and then decayed by an order of magnitude over the course of several million cycles. For both modes of behavior, abrasive wear is the governing mechanism, the difference being attributed to variations in the local surface morphology (and wear debris) between the sliding surfaces. The oxidation of worn polysilicon surfaces only affects the friction coefficient after periods of inactivity (>30 min).
Detection of Organophosphate Gases and Biological Molecules using Embedded Piezoresistive Microcantilever Sensors
Authors: Porter Tim L , Vail Tim , Venedam Richard J
Published: April 2011

Embedded piezoresistive microcantilever (EPM) sensors have been used in the detection of a variety of analyte species. EPM sensors utilize a tiny piezoresistive microcantilever partially embedded into a sensing material to produce a sensing element that is compact, simple, resistant to movement and shock, and suitable for remote sensing applications. In the current project, we have used sensing materials comprised of an immobilizing polymer functionalized with either target enzymes or antibodies to detect two biological agents, Bacillus subtilis and Diisopropyl fluorophosphate (DFP). DFP is used as a simulant for organophosphate nerve agents, while BG is a large bacterial spore used as a simulant for other bacterial spores such as bacillus anthracis. Sensing results are presented for both types of EPM sensors.
Nanomechanics of Self-Assembled Monolayers on Nanoscale Gold Films
Authors: Aponte-Roman Milca I , Mann Adrian B
Published: April 2011

Self-assembled monolayers (SAMs) are thin organic films formed by a single layer of molecules adsorbed on a substrate. Since their discovery the preparation of these molecular assemblies has attracted the attention of interfacial researchers interested in controlled wetting of surfaces, adhesion, friction, chemical sensing, and high resolution lithography. However, little effort has gone into understanding how this nano-layer affects the mechanics of the underlying surface. In this study the nanomechanics of alkanethiolate SAMs on Au (111) films has been investigated using nanoindentation techniques. The research is aimed at establishing the effect of a SAM on the measured mechanical properties of the Au film. The SAMs considered for this study were made from 1-decanethiol, 96% (CH3(CH2)9-SH). Nanoindentation experiments were performed using a Triboindenter (Hysitron Inc., MN) using displacement control mode. Comparisons were made between the mechanical behavior of the Au films, the Au films plus SAMs and the glass substrate. A range of maximum indentation displacements were used. During the nanoindentation tests the load-displacement curves and the apparent mechanical properties were found to depend on the presence of the SAM film. Surprisingly, the effects of the SAM layer are seen even when the nanoindentation displacement is orders of magnitude greater that the SAM thickness. Many of the effects of the SAM can be explained by changes in the contact geometry and the ability of the SAM to sustain compressive loads when it is in a confined volume. The results and conclusions are potentially relevant to all thin adsorbed organic films, including protein layers on biomaterial surfaces and lubricants on engineering components.
Modeling of Dislocations and Mismatched Layers in Pentagonal Nanorods
Authors: Romanov Alexei L. , Romanov Alexei E.
Published: April 2011

Pentagonal nanorods (PNRs) are crystalline objects with unique fivefold symmetry. They are often experimentally observed for materials with FCC crystal structure. In an ideal case a PNR consists of five elastically distorted but otherwise perfect crystalline regions divided by low-energy twin boundaries. The elastic distortions in PNRs and associated stored elastic energy are effectively described in the framework of a disclination approach. As a result of mechanical stress relaxation, the stored energy can be diminished in expense of structural defect formation in PRN interior. It is demonstrated that a perfect multiple twinned PNR structure is unstable with respect to dislocation formation, i.e. prismatic dislocation loop or straight edge dislocation, for PNRs above a certain critical diameter. A new mechanism for the relaxation processes in PNRs is theoretically investigated. This mechanism assumes the formation of the shell possessing crystal lattice mismatch with respect to the PNR core region. The optimal magnitude for core/shell crystal lattice mismatch and optimal shell thickness providing maximum energy release for this mechanism of mechanical stress relaxation, are predicted.
Mechanical Properties of Evaporated Gold Films. Hard Substrate Effect Correction
Authors: Du Ke , Pang Xiaolu , Chen Chi , Volinsky Alex A.
Published: April 2011

Nanoindentation tests using the Berkovich indenter tip were performed on 50 and 200 nm thick polycrystalline gold films deposited on hard substrates. Gold film hardness increased with the indentation depth due to the influence of the substrate. A procedure based on the Joslin-Oliver method was introduced to correct for the substrate effect. The method utilizes the fact that the measured elastic modulus does not change significantly with the indentation depth, which allows reducing the contact area variation used in the hardness calculation.
Shape deformation of colloidal titania nanoparticles by means of ion irradiation
Authors: Cheang-Wong Juan-Carlos , Díaz-Fonseca Ana-Lilia
Published: April 2011

Spherical submicrometer-sized titanium dioxide (TiO2 or titania) particles were prepared by the sol-gel method from hydrolysis and condensation of titanium butoxide Ti(OC4H9)4 using ammonia as a catalyst in ethanol/acetonitrile and annealing in air at 100°C. Subsequently, they were deposited onto silicon substrates, in order to form a monolayer of TiO2 particles. Then these samples were irradiated at room temperature with Si2+ ions at 4, 6 and 8 MeV, with fluences in the 2×1014-2×1015 Si/cm2 range, under an angle of 45° with respect to the sample surface. The titania particles were characterized by scanning electron microscopy to determine their size and shape before and after the ion irradiation. After the Si irradiation the spherical silica particles turned into ellipsoidal particles, as a result of the increase of the particle dimension perpendicular to the ion beam and the decrease in the direction parallel to the ion beam. This deformation effect increases monotonically with the ion fluence, and depends on the electronic energy loss of the impinging ion.
Plasma ion heating produces L10 FePt nanoclusters
Authors: Patterson Marlann Marinho , Rui Xiangxin , Li Xingzhong , Shield Jeff E. , Sellmyer David
Published: April 2011

In this study, cubic and spherical FePt clusters were created by inert gas condensation in an argon-helium dc sputter discharge under different flow and target power conditions. The plasma recipes for spherical and cubic clusters called for high He:Ar ratio, low target power and low He:Ar ratio, high target power, respectively. As expected, Langmuir probe measurements show the recipes led to larger ion density for the cubic case (2 × 108cm−3versus 6 × 106cm−3for spherical). We conclude that the larger density of argon ions increased the cluster-ion collision probability, heating the clusters in situ to promote atomic rearrangements and the formation of the orderedL10crystal structure rather than the disordered fcc structure.
Non-Hydrolytic Solution-Phase Synthesis of Anisotropic LiNbO3 and Nb2O5 Nanostructures
Authors: Wood Bryan D. , Gates Byron  D.
Published: April 2011

This paper describes an innovative and simple technique to synthesize anisotropic nanostructures of both lithium niobate (LiNbO3) and niobium oxide (Nb2O5). These materials were obtained using a solution-phase non-hydrolytic decomposition of LiNb(OPri)6 with or without the presence of Nb and Li-chlorides. The stability of LiCl is suggested as an explanation for the lack of LiNbO3 production in the chloride-based reaction. After 2 and 24 hours of reaction crystalline products of Nb2O5 and LiNbO3 are obtained without further thermal treatment. The products of both reactions contained a mixture of spherical and rod-like morphologies. Larger crystals of LiNbO3 and Nb2O5 were predominantly found to be anisotropic with aspect ratios of 7:1 and 3:1, respectively. These structures are believed to result from the natural anisotropy of the unit cell for these materials and from the use of triphenylphosphine oxide (TPPO) as a coordinating solvent. Our solution-phase synthesis is easily scaled-up as a one-pot procedure that offers a promising route to controlling crystal size and morphology. Details of the composition and the growth of our LiNbO3 and Nb2O5 nanostructures will be discussed in addition to the details of our experimental procedure.
Use of Focused Ion Beam Milling for Patterned Growth of Carbon Nanotubes
Authors: Chen Ying , Chen Ying , Chen Hua , Williams James S
Published: April 2011

A new template technique has been developed to help patterned growth of carbon nanotubes (CNTs) on Si surface without predeposition of metal catalysts. Focused ion beam (FIB) milling was used to create trenches on Si wafer surface as the template and carbon nanotubes only nucleated and grew inside the trenches during a controlled pyrolysis of iron phthalocyanine at 1000oC. The selective growth in the trenches is due to its special surface morphology, crystalline structure and capillarity effect.
A Scheme for Blocking Non-Specific Antibody Binding on Single Wall Carbon Nanotubes
Authors: Teker Kasif
Published: April 2011

Carbon nanotubes have many unique properties such as high surface area, hollow cavities, and excellent mechanical and electrical properties. Interfacing carbon nanotubes with biological systems could lead to significant applications in various disease diagnoses. Significant progress in interfacing carbon nanotubes with biological materials has been made in key areas such as aqueous solubility, chemical and biological functionalization for biocompatibility and specificity, and electronic sensing of proteins. Bioconjugated nanotubes combined with the sensitive nanotube-based electronic devices would enable sensitive biosensors toward medical diagnostic. Furthermore, recent findings of improved cell membrane permeability for carbon nanotubes would also expand medical applications to therapeutics using carbon nanotubes as carriers in gene delivery systems. One of the main issues in nanobio systems is the specificity, which requires biofunctionalization of nanomaterials for recognition of only one type of target biomolecule. This study presents an effective functionalization scheme for preventing non-specific antibody binding on nanotubes. Non-specific antibody binding on nanotubes was successfully prevented by co-adsorption of a bio-compatible polymer PEG and a surfactant (NaDDBS) on nanotubes. Optical studies through confocal microscopy revealed very minimal non-specific antibody binding on the PEG/NaDDBS-coated nanotubes (WCC < 0.05) compared to high degree of non-specific antibody binding on nanotubes without PEG pretreatment (WCC > 0.80), as determined by weighted co-localization coefficients (WCC). In addition to the confocal microscopy studies, electronic detection studies revealed that PEG/NaDDBS pretreated devices exhibited very little conductance change due to antibody adsorption compared to the devices without any PEG/NaDDBS pretreatment. These findings indicate that the PEG/NaDDBS pretreatment is a very effective functionalization scheme in preventing non-specific antibody binding on nanotubes.
Ion Conductance of Cylindrical Solid State Nanopores Used in Coulter Counting Experiments
Authors: Petrossian Leo , Wilk Seth J , Joshi Punarvasu , Goryll Michael , Posner Jonathan D , Goodnick Stephen M , Thornton Trevor J
Published: April 2011

Nanoscale apertures that provide a fluidic path between two reservoirs can be used for numerous applications. These applications include patch-clamp type measurements, Coulter counting and molecular studies. For Coulter counting of nanometer-sized analytes, we have developed a process capable of reproducibly fabricating cylindrical apertures in a silicon-on-insulator substrate with diameters less than 30 nm. The fabrication process utilizes electron beam lithography for the lithographic definition of the apertures enabling accurate control of final device dimensions. Measurements of the conductance of the pores as a function of KCl concentration reveal the presence of a surface conduction mechanism that dominates the conductance of the nanopore and leads to a deviation of the concentration dependence of the conductance from the case of bulk solution. From current traces recorded, the passage of individual particles through the pore can be concluded.
Micropatterned Biorecognition Surfaces on Nonbiofouling Polymer by Living Radical Photopolymerization for High Sensitivity Biosensing
Authors: Takai Madoka , Sibarani James , Ishihara Kazuhiko
Published: April 2011

Preparation of nonbiofouling surface and micropatterned biorecognition layer over nonbiofouling for highly sensitive microarray biosensors, was conducted by constructing biocompatible poly(2-methacryloyloxyethyl phosphorylcholine(MPC)) brushes on polymer substrates based on living radical polymerization using macrophotoiniferters comprised of 2-ethylhexyl methacrylate (EHMA) and 4-vinylbenzyl N,N-diethyldithiocarbamate (VBDC). Protein adsorption on these modified surfaces significantly reduces compared to on polymeric substrate and the micropatterning consisted of poly(MPC) brush and biorecognition layer can be easily done by applying photomask with high fidelity.
Viscoelastic property and hydration level variations of proteins multilayer adsorbed on liquid crystal phthalocyanine thin film
Authors: Paul Sharmistha , Basova Tamara , Ray Asim K.
Published: April 2011

Well established quartz crystal microbalance with dissipation (QCM-D) monitoring technique has been applied here for investigation the adsorption kinetics of three different proteins (BSA, IgG, Lysozyme) on thin film of liquid crystal copper octakishexylthiophthalocyanine [(C6S)8PcCu] surface. Modification of phthalocyanine surface by protein coating can be useful for photo dynamic therapy or in biomedical devices purpose in order to increase biocompatibility. The adsorption kinetics on vertically oriented molecular stacks of phthalocyanines were different for three proteins. Lysozyme reached to saturation quickly compare to BSA and IgG. Changes in resonance frequency and dissipation for three overtones were fitted with the Voigt viscoelastic model to calculate the shear viscosity and shear elastic modulus for the adsorbed proteins. Sauerbrey equation was used to calculate approximate adsorbed mass directly from frequency change. Adsorbed mass calculated from Voigt model was different from Sauerbrey equation. Hydration level of adsorbed protein layer was calculated from the difference in mass based on above two methods which was increased with concentration from 10-80% for BSA and IgG whereas it decreased from 20-1% for Lysozyme. Variation of viscosity and shear elastic modulus with concentration is opposite for BSA, IgG than Lysozyme. Depending on the hydration levels, adsorbed BSA and IgG formed soft (viscoelastic) layer compare to rigid layer of Lysozyme on (C6S)8PcCu surface.
Electrical and Chemical Control of Surfaces for DNA Immobilization and Hybridization
Authors: Cabeca Ricardo , Prazeres D. M.F. , Chu V. , Conde J. P.
Published: April 2011

We present the design of two biointerfaces on a SiO2 substrate for single stranded DNA (ssDNA) immobilization using either covalent grafting or electrostatic adsorption. The influence of the type of biointerface on the rate of diffusion-limited hybridization reaction with complementary ssDNA from a solution is studied. Patterning of the biointerfacefunctionalization layers and the scaling down of the reaction volumes to µL range is demonstrated. The use of externally applied electric field pulses is shown to accelerate the hybridization reaction kinetics to the sub-ms time scale.
Bioengineering of bacterial magnetic particles and its application to estrogen receptor-ligand binding assay
Authors: Yoshino Tomoko , Kaji Chihiro , Matsunaga Tadashi
Published: April 2011

Magnetic particles are used for various biomedical applications because they are easy to both handle and separate from biological samples. Nano-sized bacterial magnetic particles (BacMPs) that display the human estrogen receptor ligand binding domain (ERLBD) on their surfaces were successfully produced by the magnetotactic bacterium,Magnetospirillum magneticumAMB-1. A receptor assay for endocrine-disrupting chemicals using ERLBD-displaying BacMPs was developed. A BacMP membrane-specific protein, Mms16 or Mms13, was used as an anchor protein to localize the ERLBD on the surfaces of BacMPs. ERLBD-BacMP complexes were assayed for competitive binding of alkaline phosphatase-conjugated 17β-estradiol (ALP-E2). Inhibition curve of ALP-E2 to the powerful antagonist, tamoxifen was generated by measuring decreases in luminescence intensity that resulted from the enzymatic reaction of alkaline phosphatase. The overall simplicity of this receptor-binding assay results in a method that can be easily adapted to a high-throughput format.
Bioanalogous Recognition with Sol-Gel Thin Films and Nanoparticles in Harsh Environments
Authors: Lieberzeit Peter A. , Afzal Adeel , Mujahid Adnan , Dickert Franz
Published: April 2011

Sol-gel thin films and nanoparticles can be functionalized by imprinting strategies based on self-organization of the polymer precursors around a template compound. The resulting rugged layers are highly suitable for operating as sensor layers in harsh environments, such as engine oils. By adding e.g. dimethyl formamide or polyethylene glycol to titanate sols, the resulting layers show substantially increased sensitivity due to higher porosity and accessibility of the recognition sites. The same is true for nanoparticles, where the sensor effects are directly correlated to particle dimensions. Furthermore, also imprinted ZrO2 nanoparticles show very appreciable selectivity.
One-step separation of CD20+cells from whole blood using bacterial magnetic particles displaying protein G
Authors: Takahashi Masayuki , Yoshino Tomoko , Takeyama Haruko , Matsunaga Tadashi
Published: April 2011

Magnetic separation of target cells from mixtures, such as peripheral blood and bone marrow, has considerable practical potential in research and medical applications. Among the current cell separation techniques, magnetic cell separation using immunomagnetic particles has been routinely applied and has proven rapidness and simplicity.Magnetospirillum magneticumAMB-1 synthesizes intracellular nano-sized bacterial magnetic particles (BacMPs) that are individually enveloped by a stable lipid bilayer membrane. BacMPs, which exhibit strong ferrimagnetism, can be collected easily with commercially available permanent magnets. In this study, a novel magnetic nanoparticle displaying protein G (protein G-BacMPs) was fabricated, and one-step cell separation for direct cell separation from whole blood was performed using the protein G-BacMPs. B lymphocytes (CD20+cells), which cover less than 0.3×10−2% of whole blood cells, were separated with 93% purity using protein G-BacMPs binding with anti-CD20 monoclonal antibodies. The results of this study demonstrate the utility of protein G-BacMPs and the magnetic cell separation approach based on protein G-BacMPs in numerous applications.
Synthesis and Characterization of Photocurable Polyionic Hydrogels
Authors: Desai Pooja N , Yang Hu
Published: April 2011

In this study we describe preparation of polyionic hydrogels based on PEGylated polyamidoamine (PAMAM) dendrimers. Polyethylene glycol (PEG) with varied chain length (MW=1500, 6000, or 12000) was first conjugated to the Starburst™ G3.0 PAMAM dendrimer to form stealth dendrimers. The free hydroxyl group of PEG was further converted to an acrylate group using acrolyl chloride and triethylamine. The conjugation was characterized with 1H-NMR. The loading degree of PEG on the dendrimer surface was estimated by using both the ninhydrin assay and 1H-NMR. Hydrogel formation was realized by subjecting dendrimer-PEG acrylate to UV exposure for a brief period of time at the presence of Eosin Y, triethanolamine and 1-vinyl-2-pyrrolidinone. PEGylated G3.0 PAMAM dendrimer served as cross-linking agent to form hydrogels because of its multiple functionalities. The surface charges conferred by terminal groups on the dendrimer surface made the hydrogel polyionic with controllable charge density. This new type of hydrogel has many favorable biological properties such as non toxicity and non immunogenecity and multifunctional ties for a variety of in vivo applications. Current studies have demonstrated feasibility of chemistry and hydrogel formation.
Micromachined Linear Brownian Motor: A Nanosystem Exploting Brownian Motion of Nanobeads for Uni-directional Transport
Authors: Altintas Ersin , Sarajlic Edin , Bohringer Karl F. , Fujita Hiroyuki
Published: April 2011

Nanosystems operating in liquid media may suffer from random thermal fluctuations. Some natural nanosystems, e.g. biomolecular motors, which survive in an environment where the energy required for bio-processes is comparable to thermal energy, exploit these random fluctuations to generate a controllable unidirectional movement. Inspired by the nature, a transportation system of nanobeads achieved by exploiting Brownian motion were proposed and realized. This decreases energy consumption and saves the energy compared to ordinal pure electric or magnetic drive. In this paper we present a linear Brownian motor with a 3-phase electrostatic rectification aimed for unidirectional transport of nanobeads in microfluidic channels. The transport of the beads is performed in 1 μm deep, 2 μm wide PDMS microchannels, which constrain three-dimensional random motion of nanobeads into 1D fluctuation, so-called tamed Brownian motion. We have experimentally traced the rectified motion of nanobeads and observed the shift in the beam distribution as a function of applied voltage. The detailed computational analysis on the importance of switching sequence on the speed performance of motor is performed and compared with the experimental results showing a good agreement.
Characterization of Materials for a Hydrogen-Based Economy by Cold Neutron Prompt Gamma-Ray Activation Analysis
Authors: Paul Rick , Cao Lei Raymond
Published: April 2011

An instrument for cold neutron prompt gamma-ray activation analysis (PGAA) at the NIST Center for Neutron Research (NCNR) has proven useful for the chemical characterization of hydrogen storage materials and other materials of importance to a hydrogen-based economy. The detection limit for hydrogen is less than 10 mg/kg for most materials. Potential hydrogen storage materials that have been characterized by PGAA include single-wall carbon nanotubes with and without boron doping, porous carbons, lithium magnesium imides, and ternary hydrides of various elements. The capability to allow in situ hydrogenation and characterization of materials is currently under development. PGAA has also been used to characterize materials used in hydrogen fuel cells, including solid proton conductors, polymer membrane, and proton exchange membranes. Future upgrades to the instrument will improve detection limits and functionality of the instrument.
Ab Initio Alloying of Mg for Hydrogen Storage
Authors: Kecik Deniz , Aydinol Mehmet Kadri
Published: April 2011

A candidate hydrogen storing material should have high storage capacity and fast dehydrogenation kinetics. On this basis, magnesium hydride (MgH2) is an outstanding compound with 7.6 wt% storage capacity, despite its slow dehydriding kinetics and high desorption temperature. Therefore in this study, formation energies of alloyed bulk MgH2, adsorption energies on alloyed magnesium (Mg) and MgH2 surface structures were calculated by total energy pseudopotential methods. Also, the effect of substitutionally placed dopants to the dissociation of hydrogen molecule (H2) at the surface of Mg was investigated via Molecular Dynamics (MD). The results show that 31 out of 32 selected dopants decreased the formation energy of bulk MgH2, within a range of ˜37 kJ/mol-H2 where only Sr did not display any such effect. The most favorable elements in this respect are; P, K, Tl, Si, Sn, Ag and Pb. Moreover, surface adsorption energy values display that all elements are adsorbed substitutionally on the clean (0001) surface of Mg where adsorption on MgH2 (001) surface is possible only for alloying elements other than Zn, Au, In, Ag, Li, Tl, Cd, Na and K. Finally, results of MD simulations point out that the elements giving rise to the dissociation of hydrogen molecule came out to be Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Ru, Rh ve Hf.
Effect of Pore Size on Dehydrogenation Temperature of Carbon Cryogel-Ammoniaborane Nanocomposites
Authors: Sepehri Saghar , Batalla Garcia Betzaida , Cao Guozhong
Published: April 2011

This study reports the effects of pore size of porous carbon scaffold on the dehydrogenation of ammoniaborane in the coherent carbon- ammoniaborane nanocomposites. Porous carbon scaffold is obtained from resorcinol formaldehyde derived carbon cryogels. The nanocomposites are made by simple soaking porous carbon scaffold in ammonia borane solution. Nitrogen sorption analysis and differential scanning calorimetry are used to investigate the structure and dehydrogenation of the nanocomposites. The results reveal that dehydrogenation temperature decreases in nanocomposites as compared to neat ammonia borane, and is lower in nanocomoposites with smaller pore sizes. These findings can be used to tune the dehydrogenation temperature to meet specific hydrogen storage applications. Also, dehydrogenation kinetics of nanocomposites is enhanced as compared to neat ammonia borane.
Anode Composites Based on NiO and Apatite-Type Lanthanum Silicate for Intermediate Temperature Solid Oxide Fuel Cells
Authors: Kharlamova Tamara , Pavlova Svetlana , Sadykov Vladislav , Krieger Tamara , Alikina Galina , Frade Jorge , Argirusis Christos
Published: April 2011

Composite materials based on NiO and doped apatite-type lanthanum silicates (ATLS) that are new class of solid electrolytes were studied as anode materials for intermediate temperature solid oxide fuel cells (IT SOFC), with possibility to use both H2 and CH4 as a fuel being payed attention to. For cermets preparation different methods of Ni addition such as incipient wetness impregnation, modified Pechini methods or mechanical mixing were used. The composite materials were characterized by XRD, BET, TPO and methane steam reforming reaction. Doping with complex oxides possessing a high mobility of the lattice oxygen and partial Ni substitution by the mixed conductor were applied to improve anode stability to coking.
Design and Characterization of Nanocomposites Based on Complex Perovskites and Doped Ceria as Advanced Materials for Solid Oxide Fuel Cell Cathodes and Membranes
Authors: Sadykov Vladislav , Kharlamova Tamara , Batuev Lubsan , Mezentseva Nathalia , Alikina Galina , Muzykantov Vitalii , Krieger Tamara , Pavlova Svetlana , Zaikovskii Vladimir , Ishchenko Arcady , Zarubina Valeria , Rogov Vladimir , Bobrenok Oleg , Uvarov Nikolai , Kilner John , Druce John , Smirnova Alevtina
Published: April 2011

La0.8Sr0.2Fe0.6Ni0.4O3-x - Ce0.9Gd0.1O2-x and La0.8Sr0.2Fe0.8Co0.2O3-x - Ce0.9Gd0.1O2-x nanocomposites were synthesized via ultrasonic dispersion of nanocrystalline powders of perovskite and fluorite oxides in acetone with addition of a surfactant, followed by drying and sintering at temperatures up to 1200°C. The evolution of the structure of samples with sintering temperature was studied by XRD and TEM with EDX and compared with the data on conductivity, oxygen isotope exchange, O2 TPD, H2 and CH4 TPR. Preliminary testing of button-size cells with cathodes supported on thin YSZ layer covering Ni/YSZ cermet demonstrated a high and stable performance of LSNF–GDC composite promising for the practical application.
Modeling Particle Size Effects on Phase Stability and Transition Pathways in Nanosized Olivine Cathode Particles
Authors: Tang Ming , Huang Hsiao-Ying , Meethong Nonglak , Kao Yu-Hua , Carter W. Craig , Chiang Yet-Ming
Published: April 2011

Recent experiments show that nanosized olivine LiFePO4 has different phase transition and solubility behavior than that of larger cathode particles. The possibility of metastable or globally stable amorphous phase in nanosized LiFePO4 particles during delithiation is considered in a diffuse-interface model. At a small enough particle size, a lithiated crystalline phase can undergo amorphization upon charging instead of transforming directly to the delithiated crystalline phase at nanoscale particle sizes.
Experimental Limits of Light Capture in Thin Film Silicon Devices
Authors: Poruba Ales , Klapetek Petr , Holovsky Jakub , Purkrt Adam , Vanecek Milan
Published: April 2011

New approach for the determination of the angular distribution of the scattered light at nano-rough surfaces/interfaces from AFM (Atomic Force Microscopy) data is presented. Calculation comes from modeling the electromagnetic field in the tight vicinity of the nano-rough surface by complex solution of Maxwell's equations and subsequent near field to far field transform. This method is demonstrated for four types of transparent conductive oxides (with rough free surfaces) deposited on glass substrates. As a result we have the amount and angular distribution of the scattered light „observed” in both transmission and reflection. Moreover calculation can be done for real sample dimensions (to compare the results with the measurement of the angular distribution function using LED laser) or for a semi-infinite sample which suppresses the interference effects and thus such distribution functions can be used as an input parameter for our 3-dimensional optical model CELL for thin film silicon solar cell modeling.

In the second part of this contribution we describe our experiment of thin film silicon solar cell characterization by Light Beam Induced Current (LBIC). This measurement done for laboratory solar cell structures reveals the light scattering and light trapping properties of the multilayer stack on a glass substrate. We suggest the test structure for the direct back reflector quality comparison and thus also for its optimization.
Processing and Characterization of Efficient Thin-Film Polycrystalline-Silicon Solar Cells
Authors: Gordon Ivan , Van Gestel Dries , Qiu Yu , Venkatachalam Srisaran , Beaucarne Guy , Poortmans Jef
Published: April 2011

Efficient thin-film polycrystalline-silicon (pc-Si) solar cells on inexpensive substrates could substantially lower the price of photovoltaic electricity. We recently showed that good solar cells can be made from pc-Si obtained by epitaxial thickening using thermal CVD of a seed layer made by aluminium-induced crystallization (AIC) of amorphous silicon. We already reported cells in substrate configuration with energy conversion efficiencies up to 8.0% for layers on ceramic alumina substrates. However, much higher efficiencies (η > 10%) are needed for this type of pc-Si solar cells to become cost-effective. To achieve these higher efficiencies, cells will probably have to be made in a superstrate configuration on transparent substrates and advanced light trapping will need to be applied. In this paper we report on our recent progress with pc-Si solar cells made on transparent glass-ceramic substrates.

So far, our best pc-Si solar cells in substrate configuration on glass-ceramics showed an efficiency of 6.4%. By using plasma texturing to lower the front side reflection, we increased the current density of our cells by roughly 1 mA cm-2. The Jsc is much lower for cells on glass-ceramic than for cells on alumina. This is the result of the better diffuse back reflectance of alumina compared to glass. The Voc and fill factor are comparable for cells on both substrates.

To make pc-Si solar cells on glass in superstrate configuration, we will use a-Si/c-Si rear junction emitters. As a first test of the feasibility of this approach, we measured the illuminated IV parameters of pc-Si cells made for the substrate configuration in superstrate configuration. In superstrate configuration, the current density of the cells is much lower than in substrate configuration due to the non-optimized cell design for superstrate illumination. The Voc is slightly smaller in superstrate configuration due to the lower current density.

These results indicate that the glass-ceramic substrates are fully compatible to our poly-Si solar cell process. Furthermore, rear-junction poly-Si cells in superstrate configuration should lead to good cell results once the absorber layer thickness is optimized to the diffusion length of the material and light trapping features adapted to the superstrate configuration are applied.