bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Different Capillary Geometries on the Plug Distortion in Hybrid Micro Channels
Authors: Storsberg Lars , Schöler Lars , Seibel Konstantin , Schäfer Heiko , Walder Marcus , Püschl René Johannes , Wenclawiak Bernd , Böhm Markus
Published: April 2011

The plug distortion for on-chip capillary zone electrophoresis systems with rectangular separation channels, manufactured in a hybrid layer system with different material properties of the vertical and the horizontal walls has been examined. Experimental data and simulation results indicate that plug widening caused by different values of the #950;-potential of the walls in contact with the fluid depends strongly on the aspect ratio of the channel cross section. If the height to width ratio is much greater or much smaller than 1, as is often the case for commonly used labchip architectures, plug widening may be negligible. The difference of the #950;-potentials between the vertical and the horizontal side walls has been determined from the shape of the plug edges. For an architecture using glass for the top and bottom walls, but SU-8 for the side walls, the difference of the #950; potentials was measured to be on the order of only 2.4 mV for a pH of 9.2, suggesting that such device architectures may be used for on-chip electrophoresis analysis without uniform coating of the channel inside for less demanding applications.
Materials Strategies for Advanced Nano Technology
Authors: Choi Kyung
Published: April 2011

We demonstrate functional microfabrications generated using photocurable functional polymers. We synthesized photocurable silicon elastomers, which can be useful for high fidelity, nano-scale soft lithography. ‘Elastic photopatterns’ generated by using the designed photocuarble silicon elastomers was presented. Molecularly imprinted polymers (MIP) are produced by “molecular imprinting technique”, which is a general protocol for the preparation of “synthetic receptor sites”. We then used the MIP's system for functional pattern fabrications to improve the sensitivity of molecular recognitions. Those functional microfabrications are beneficial to develop actual devices with high performances.
Radionuclide Transport in a Water - Saturated Planar Fracture with Bentonite Extrusion
Authors: Borrelli R. A. , Ahn J.
Published: April 2011

This paper presents a radionuclide migration model that incorporates bentonite extrusion. The model consists of two parts: one for movement of water and bentonite in a planar fracture and the other for radionuclide transport by taking into account advection, diffusion, and sorption with moving bentonite particles. Numerical results indicate that strongly sorbing radionuclides are contained completely within the region of bentonite extrusion. This observation suggests importance of the region in the vicinity of buffer/rock interface in terms of impact on radionuclide release to surrounding host rock.
High Refractive Index Inorganic-Organic Hybrid Materials for Photonic Applications
Authors: Declerck Pélagie , Houbertz Ruth , Jakopic Georg , Passinger Sven , Chichkov Boris
Published: April 2011

High refractive index materials are attractive for many photonic elements. For example, 3D photonic bandgap (PBG) materials have been proposed as the basis of many devices. In order to create complete 3D PBGs, materials enabling high refractive index contrast are needed. We here report on novel high refractive index hybrid polymers. They were synthesized by hydrolysis/polycondensation reactions of organo-alkoxysilanes and Ti alkoxide precursors, resulting in organically modified inorganic-oxidic pre-polymer resins. These can be organically cross-linked by one- or two-photon polymerization (2PP). The latter method enables the writing of arbitrary 3D structures. The introduction of Ti into the inorganic-oxidic network accounts for an increase in the material's refractive index, which could be varied between 1.62 and 1.8. Optical properties such as refractive index and absorption losses were determined on an exemplary material system in the lower refractive index range. The influence of the processing parameters on the degree of organic polymerization, and the refractive index of these novel high index materials was investigated in particular. 3D photonic crystal structures were written for the first time in a high-refractive index hybrid polymer.
Mesostructured Silica Films with Metal Oxide Doped Pore Walls
Authors: Koehler Joachim , Cai Jun , Behm Rolf Juergen , Huesing Nicola
Published: April 2011

In this work, novel approaches towards mixed metal oxide mesostructured films by a combination of evaporation-induced self-assembly and sol-gel processing of deliberately designed precursor molecules (from single source precursors to metal-surfactant complexes) are reported. The focus lies on Ti-oxide doped silica films with in a wide range variable Ti to Si ratios. The ligand-assisted templating based on metal-coordinated surfactants allows a selective positioning of the metal species in the silica wall which is advantageous for many catalytic applications. For the synthesis of these metal doped silica films, a non-ionic polyether-based surfactant (Brij56) was simultaneously used as the structure-directing agent and ligand for the respective metal-alkoxide, such as titanium isopropoxide. These metal-coordinated surfactants were mixed with a prehydrolyzed silica-solution based on tetraethoxysilane and ethanol and spin- or dip coated. In the second approach, a single source precursor for network formation based on 3-acetyl-6-trimethoxysilylhexane-2-one that was coordinated to titanium isopropoxide was synthesized. This precursor was either used as network forming agent in the presence of tetraethoxysilane and a surfactant (Brij56) or in combination with the metal-coordinated surfactant to broaden the accessible range of the Si:Ti ratios. The final films were characterized by XRD, XPS, nitrogen porosimetry and TEM.
Composition and Functional Properties of Organosilicon Plasma Polymers from Hexamethyldisiloxane and Octamethylcyclotetrasiloxane
Authors: Zajickova Lenka , Kucerova Zuzana , Bursikova Vilma , Franta Daniel , Perina Vratislav , Mackova Anna
Published: April 2011

Hybrid organic-inorganic thin films with different fractions of silicon oxide were deposited in rf capacitively coupled discharges using pure hexamethyldisiloxane (HMDSO), octamethylcyclotetrasiloxane (D4) or 5 % HMDSO in O2. The deposition in continuous wave (cw) mode was compared with pulsed conditions under which the discharge on-time was 5 ms and the off-time varied from 0.5 to 15 ms. The chemical composition of the films was studied by FTIR, RBS and ERDA. Their optical properties in UV / visible / NIR were determined from spectroscopic ellipsometry and reflectance measurements fitted with a Kramers-Kronig consistent dispersion model based on a parametrization of density of states. Film hardness and reduced modulus were determined from depth sensing indentation tests.
From Polymeric to Particulate Inorganic Macrocellular Foams: Some Integrative Chemistry Synthetic Pathways
Authors: Carn Florent , Backov Rénal
Published: April 2011

Hierarchically organized matter appears today a strong and highly competitive field of research mainly induced by the wide scope of applications expected. In this context, chemistry of shapes appears as a strong interdisciplinary field of research combining soft chemistry and soft matter. Hierarchical inorganic porous silica monoliths can be obtained combining air-liquid foams either with molecular precursors promoting condensation within the foam's Plateau borders confined geometry or with pre-synthesized nanobuilding blocks that will be organized within the foam's Plateau border and films. By controlling the air-liquid foam's water liquid fraction we can design the inorganic porous texture at the macroscale (i.e. cell sizes and shapes as well as the Plateau borders thickness). Considering the nanobuilding block approach, final scaffolds are a very close transcription of the tailored periodic air-liquid foam template, while highly ordered close-packed silica colloids are texturing the as-synthesized foam walls. The interconnected nanoparticles and associated void space between adjacent particles allow generating intrinsic mesopores, thereby defining hierarchically organized porous scaffolds. The good control over both the air-liquid foam's water volume fraction and the bubble size allow a rational tuning of the macropore shapes (diameter, Plateau border's width). In contrast with previous studies, closed-cell structures can be reached, while the opal like scaffold structure is maintained with thermal treatment, avoiding thus strong shrinkage associated to the sintering effect.
Nacre-like TiO2 - and ZnO- Based Organic / Inorganic Hybrid Systems
Authors: Burghard Zaklina , Bauermann Luciana Pitta , Tucic Aleksandar , Jeurgens Lars P. H. , Srot Vesna , Bellina Paul , Lipowsky Peter , Hoffmann Rudolf C. , Gutmanas Elazar , Bill Joachim , Aldinger Fritz
Published: April 2011

A bioinspired approach combining chemical bath deposition (CVD) of oxides with layer-by-layer (LBL) assembly of organic polymers has been used to prepare two different types of organic/inorganic multilayer composite films, whose morphology resembles that of naturally occurring nacre. Both process steps allow for a precise control of the layer thickness, thus enabling to tailor the architecture of the multilayer composites. The first type of composite films comprised of TiO2 layers, separated by organic interlayer composed of several oppositely charged polyelectrolytes, while the second type of composite films contained ZnO as the inorganic and poly (amino acids) as the organic component. AFM investigations revealed a granular structure of the inorganic layers which originates from the oxide particles. TEM investigation disclosed that the TiO2 particles are amorphous, while the ZnO particles are crystalline. Moreover, TEM cross-sectional analysis of the composite films confirmed the presence of inorganic layers that are well-separated by organic layers, although signatures of partial interpenetration have been observed at the interfaces. The hardness and Young's modulus of both types of composite films, as determined by nanoindentation testing, increased in comparison to the monolithic oxide films. The enhanced mechanical performance underlines the effectiveness of combining layers of different shear moduli into an alternate architecture.
Effect of the Sol-Gel Synthesis Parameters on the Incorporation of an Anti-inflammatory Drug in a Ceramic Material
Authors: Hernandez Aracely , Esquivel-Ferriño Patricia , Gomez Idalia , Cantu Lucia
Published: April 2011

In the present work, sol-gel method was used to incorporate in a ceramic material a non steroidal anti-inflammatory drug (piroxicam) as model drug. The incorporation of the drug in the SiO2 network was carried out at different sol-gel synthesis parameters, such as pH (3 and 5) and the alkoxide/water ratio (1:6 and 1:8). The biomaterial obtained was analyzed by thermal analysis TGA-DTA, infrared spectroscopy (FTIR), Scanning Electronic Microscopy (SEM) and X-ray diffraction (XRD); specific surface area and porosity were analyzed from nitrogen adsorption isotherm. Better drug incorporation into the material was achieved at the synthesis conditions of pH 5 and 1:6 alkoxide/water molar ratio.
Covalent Grafting of Organoalkoxysilanes on Silica Surfaces in Water-Rich Medium as Evidenced by 29Si NMR
Authors: Bonhomme Christian , Monredon Sophie De , Ribot François , Babonneau Florence
Published: April 2011

Despite the huge amount of experimental investigations dedicated to the grafting of organoalkoxysilanes on silica, the characterization of covalent linkages remains a difficult task from a spectroscopic point of view. In most cases, the formation of a covalent link is taken for granted and not discussed. 29Si NMR, IR or UV spectroscopies are commonly used to study the modification of silica surface. Herein we report an unambiguous method to evidence the formation of covalent links. It is based on NMR spectroscopy analysis coupled with a rigorous synthetic grafting protocol.
Luminescent Silica Thin Films
Authors: Neouze Marie-Alexandra G. G. , Schubert Ulrich
Published: April 2011

Luminescent silica films were prepared by sol-gel synthesis under acidic conditions in the presence of fluoride ions. Luminescence was observed for both the pure inorganic film or film of a silica-based inorganic-organic hybrid material. Powders prepared from the same precursor mixtures were only fluorescent after calcination.
Conjugated Polymers as Part of Multifunctional Organic/Inorganic Hybrid Materials for Photovoltaic Applications
Authors: Lira-Cantu Monica , Krebs Frederik C. , Gomez-Romero Pedro , Yanagida Shozo
Published: April 2011

The multifunctionality of hybrid organic-inorganic materials has been clearly demonstrated in recent years. Their application in solar- related devices is a growing research area with important technological implications. Our interest is centered on the interplay between the light-harvesting and hole-conducting properties of conjugated polymers and the wide band gap values observed from different inorganic semiconductor oxides. The materials applied in this work are the combination of semiconductor oxides like TiO2, ZnO, Nb2O5, CeO2 and TiO2-CeO2, and different conjugated polymers like poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) or poly(3,4-ethylenedioxythiophene) (PEDOT). Semiconductor oxides have been applied in different configurations like dense thin films, nanostructured electrodes or as nanoparticles. The conjugated polymers have been chosen depending on their light-harvesting properties (e.g. MEH-PPV) or due to their good electrical conductivity and hole conducting properties (e.g. PEDOT). We have characterized our devices in terms of Voc, Jsc, IV-curves, effect of different atmospheres and device lifetime under simulated sunlight irradiation. Tuning the different device parameters such as type of oxide applied, active layer thickness, starting materials concentration, effect of different atmospheres, effect of UV irradiation, etc., permit the fabrication of devices with well-defined properties. A brief discussion and comparison of hybrid solar cells (HSC) with solid-state Dye Sensitized Solar Cells (ss-DSC) applying nanocomposite materials based on TiO2 and PEDOT, as the electron and hole conducting materials respectively, is also included.
Influence of Lysozyme on the Biomimetic Growth of Silica Tubes in Porous Membranes
Authors: Gautier Clémentine , Courson Rémi , Lopez Pascal Jean , Livage Jacques , Coradin Thibaud
Published: April 2011

Pore channels of poly-carbonate membranes were recently used as biomimetic models to study the effect of confinement on silicate condensation, leading to the formation of silica tubes exhibiting a core-shell structure. In this work, we pre-immobilized lysozyme on the membrane pores, inducing the modification of the tube shell formation process, and variation in core particle size. These data strengthen previous assumptions on the role of interfacial interactions on the growth of the tube shell and indicate that such interactions also influence the core particle formation. Such approach therefore seems suitable to mimic the formation of silica/protein multilayers as found in several biomineralizing organisms
Carbon and Steel Surfaces Modified by Leptothrix Discophora SP-6: Characterization and Implications
Authors: Nguyen Tuan Anh , Lu Yuzhuo , Song Shizhe , Shi Xianming
Published: April 2011

Leptothrix discophoraSP-6, a type of manganese(Mn)-oxidizing bacteria, has been known to accumulate Mn oxides from the aqueous environment and thus play a key role in microbiologically influenced corrosion by increasing the electrochemical potential of steel and other metals. Similarly, this bacterium was found to modify the surface of glassy carbon in aqueous solution and increase its potential (i.e. ennoblement). In the latter case, biomineralized Mn oxides can be used as cathodic reactants for a new generation of microbial fuel cells featuring a bio-cathode. In this preliminary study, factors affecting the biofilm formation and biomineralization processes were examined. The inflow of air into the culture medium was found essential to sustain the ennoblement of substrate electrodes. The OCP and FESEM/EDS data indicated that a smoother initial substrate surface generally led to better ennoblement. Polarizing the carbon electrode at +500mVSCE for 15 minutes was found to facilitate the ennoblement on carbon electrodes, and so did the coating with a poly(L-lysine) layer. Independent of substrate material, initial surface roughness and pretreatment, there were three parameters in the EIS equivalent circuit that correlated well with the OCP indicating the level of ennoblement byL. discophoraSP-6, i.e., electrolyte resistance, double-layer capacitance, and low-frequencies capacitance. These fascinating findings merit further investigation as they may shed light on the fundamental bacteria/substrate interactions and help advance the knowledge base needed for the engineering applications.
Making PEG-based Microparticles for Applications in Biology and Medicine
Authors: McDonald Tom Oliver , Christensen Søren , Ulijn Rein V
Published: April 2011

We demonstrate the polymerisation of PEGA hydrogel microparticles with a mean diameter of 16 µm (similar to that of biological cells), and we show that these particles are compatible with enzymes. Furthermore, we demonstrate that enzyme catalysed reactions occur faster with these microparticles than with commercially available macrobeads which are typically 200-400 µm in diameter.
Novel Collagen Based Material for Local Drug Delivery Systems
Authors: Castaneda Luciano , Pluskat Suzanne , Ky Darline , Te Earry , Slowinska Katarzyna
Published: April 2011

In a search for new drug delivery matrix, the synthesis of a novel collagen material based on tiopronin protected gold clusters (MPC) as a crosslinking agent is proposed. The structure of collagen matrix modified with MPC is studied using transmission electron microscope. The thermal properties are examined with differential scanning calorimetry. To assess the biocompatibility of the matrix, the cytotoxicity assays are conducted.
Fabrication of CMOS Compatible Sub-micron Nails for On-chip Phagocytosis
Authors: Huys Roeland , Bartic Carmen , Meerbergen Bart Van , Braeken Dries , Loo Josine , Winters Kurt , Chen Chang , Yitzchaik S. , Spira M. , Shappir J. , Borghs Gustaaf
Published: April 2011

Neuronal research requires to efficiently perform long-time experiments on large-scale neuronal networks in a minimally invasive way. Such experiments imply stimulation and measurements of electrical activity on a large number of neurons. This could be achieved by on-chip integration of actuators, sensors and readout electronics with dimensions comparable to the sizes of neurons. Integration of biosensors at this scale creates new challenges: the processing of the sensors must be compatible with state-of-the art CMOS technology, the system must be biocompatible, and the down-scaled technology imposes restrictions on the applicable stimulation voltages and increases the electrical noise.

Recently it has been demonstrated that biological phenomena can be exploited in order to achieve the best coupling between cells and sub-micron scale electronics. Engulfment of sub-micron nail structures by the cell membrane minimizes the distance between the sensor and the cell [1], [2].

This paper presents two methods to produce nails with sizes from sub-micrometer to micrometer scales, on top of a CMOS chip. Prototype chips have been fabricated, and cells have been cultured to examine the in-vitro bio-compatibility of the chip.
A Potential of Large Scale of Dye Sensitized Solar Cells using Metallic Titanium Sheet as the Substrate for Photoelectrode
Authors: Onoda Kinji , Ngamsinlapasathian Supachai , Fujieda Takuya , Yoshikawa Susumu
Published: April 2011

The photovoltaic properties of dye-sensitized solar cells (DSCs) based on fluorine doped tin oxide (FTO) and Ti substrates were investigated. The sheet resistances of the substrates were correlated to the photovoltaic properties. The efficiency of the Ti substrate based DSC was higher than that of the FTO substrate based DSC, due to a high fill factor (FF). To minimize the internal resistance of the DSCs, Ti plate was used as a support for nanocrystalline TiO2, because of its low sheet resistance. As the light was absorbed by the electrolyte layer, the incident photon to current efficiency (IPCE) values decreased in the range between 400-600 nm. The electrolyte concentrations were optimized to obtain a higher cell performance. When using an electrolyte composed of 0.02 M I2, 0.2 M LiI, and 0.5 M 4-tert-butylpyridine, an efficiency of 4.98% was obtained for the Ti substrate based DSC with a short circuit current density (Jsc) of 11.25 mAcm-2, an open circuit voltage (Voc) of 0.692 V, and a FF of 0.639. The effect of the cell size on the photovoltaic properties was also investigated. The rate of decrease in a FF and efficiency with increase in the cell size was lower for the Ti substrate based DSCs than the FTO substrate based DSCs. This result indicates that Ti plate is a potential candidate for production of large DSCs.
Studies of Potassium Dihydrogen Phosphate (KDP) Crystals Doped with Potassium Dichromate (PD) using ICP and UV Spectrophotometer
Authors: Seif Selemani , Lal Ravindra Behari
Published: April 2011

This paper reports on preparation and characterization of Potassium Dihydrogen Phosphate (KDP) crystals doped with Potassium Dichromate (PD). The crystals were grown at room temperature by solution evaporation technique. The grown crystals were polished, sliced, and analyzed using UV-Spectrophotometer, which showed high concentration of PD impurities in KDP crystals at 200-280 nanometer. These concentrations were then verified using ICP measurements to determine specific amount in ppm of chromium ions in KDP crystals. In additional to that, the UV-transmittance data of these crystals were then converted to absorbance per thickness, and used to calculate absorption coefficients, extinction coefficients, and refractive index as a function of wavelength. The results showed that the presence of PD impurities in the crystal matrix of KDP has played a key reformative role in the UV sensing of Potassium Diphosphate crystals.
Post-annealing Induced Formation of ZnO Nanowires on the ZnO Films in the N2O Ambient
Authors: Lin Ping-Yuan , Liao Wei-Tsai , Yan Kuo-Yi , Chang Chia-Chi , Lin Hsin-Yuen , Wang Cheng-Liang , Gong Jyh-Rong , Lyu Dong-Yuan , Lin Jian-Hao , Lin Tai-Yuan , Lin Hung-Ji , Lin Der-Yuh
Published: April 2011

ZnO films were grown on (0001) sapphire substrates by atomic layer deposition (ALD) using diethylzinc (DeZn) and nitrous oxide (N2O) in an inductively heated reactor operated at atmospheric pressure. Low-temperature (LT) ZnO buffer layers having various thicknesses were deposited at 400¢J followed by subsequent growth of ZnO films at 600¢J. Some of the ZnO films were then post-annealed at 1000¢J in the N2O flow. Under certain growth conditions, ZnO nanowires were formed on the post-annealed ZnO samples. Room temperature (RT) photoluminescence (PL) spectra of the ZnO nanowires show strong ultraviolet (UV) near band edge emissions at 3.27 eV with a typical full width at half-maximum ( FWHM ) of ~130 meV and quenched defect luminescence at 2.8 eV. 10 K PL spectra of the post-annealed ZnO all exhibit sharp excitonic emissions with the dominant emission being located at 3.36 eV having a FWHM of 4.6 meV.
Improvement of Hydrogen Adsorption on Carbon Nanostructures
Authors: Lafi Lyubov , Chahine Richard , Bénard Pierre , Poirier Éric
Published: April 2011

We present results of a study of the effect of various surface treatments on the adsorption properties of hydrogen on single-walled carbon nanotubes (SWNTs) and activated carbon. The alteration of the surface area by thermal and chemical treatments of SWNTs was studied by Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and nitrogen adsorption. The Horwath-Kawazoe (HK) method was applied to describe the increase of the surface area and of the pore volume of the SWNT samples. The surface treatments lead to substantially improvement of hydrogen adsorption at 77 K and 1 atm. The averaged heat of adsorption (enthalpy), estimated from a Dubinin-Astakhov (DA) analysis, was found to be about 3.6 and 4.2 kJ/mol for heat-treated and as-received SWNTs, respectively.
Dielectric Relaxation and Dynamic Light Scattering Study of Liposome in the Aqueous Solution
Authors: Kundu Shyamal Kumar , Choe Song Gi , Yamamoto Wataru , Kita Rio , Yagihara Shin
Published: April 2011

The dynamic light scattering (DLS) has been used to investigate the diffusion behavior and the size distribution of liposome. DLS experiments show two classes of particles with their hydrodynamic radii being 4-12 nm and 66-80 nm. The numbers of particles associated with the two peaks are estimated by means of the scattering properties of the particles, which show that the overwhelming majority is big ones.

Broadband dielectric spectroscopy (BDS) has been used to investigate the dynamical structure of liposome in aqueous solution of water, which makes it possible to precisely explain the molecular mechanism, structures and various properties as a function of temperature and frequency. We have observed four relaxation processes, where two low frequency processes are commonly observed in charged macromolecules in aqueous solution, third process appeared in the MHz region due to the motion of ions, which is also related to the molecular motion of the lipid, and the high frequency process appeared about 20 GHz is due to free water surrounding liposome. Gel-LC phase transition has been described very accurately from the temperature-dependent shape parameter, β, obtained from the Cole-Cole fitting. The β value in LC phase is smaller than that in gel phase.
Active Polymer Nanoparticles: Delivery of Antibiotics
Authors: Rabinovich Monica , Somayaji Shankari N. , Raghavan Pillai Rajeev , Hudson Michael C. , Ellington J. Kent , Bosse Michael , Horton James , Gonsalves Kenneth E.
Published: April 2011

Antibiotic-encapsulated PLA and PLGA nanoparticles were prepared by the single emulsion-solvent evaporation technique. Different PLA and PLGA systems were prepared, varying the copolymer composition and the amount of the surfactant polyvinyl alcohol. Characterization and drug loading studies were performed by UV-Visible spectrophotometry, dynamic light scattering, and scanning electron microscopy (SEM).

Simultaneously, in order to model the diffusion of the nanoparticles within the osteoblast, QDs such as functionalized InGaP/ZnS and polymer encapsulated InGaP/ZnS nanoparticles were added to confluent cultures of primary mouse osteoblasts. Following PreFer fixation, cultures were examined via confocal microscopy. QDs were clearly visible within osteoblasts.
Time evolution of Nano Dots created on InP(111) surfaces by keV irradiation
Authors: Paramanik Dipak , Majumdar Subrata , Sahoo Smruti Ranjan , Varma Shikha
Published: April 2011

Fabrication of Nanodots on semiconductor surfaces has immense importance due to their application in memory and optoelectronic devices. Ion irradiation methods display an easy and cost effective route for developing self assembled structures. We have studied the formation of Nano-dots on InP(111) surfaces by 3keV Ar ion irradiation. The distribution of nano Dots on InP surfaces has been investigated by Scanning Probe Microscopy (SPM). A 5 min irradiation of InP surface with Ar ions leads to the appearance of dots on the surface. The density of dots is, however very small. These dots have been obtained at room temperature, in the absence of sample rotation, with an angle of 15 degree between the ion axis and the sample normal. After an irradiation of 10 min a large density of dots appear on InP surface and display a narrow distribution of size and height. The dots at this stage have an average diameter of 25nm and a height of 4nm. With increased irradiation time the average size and the height of the dots increase and their distribution also become broader. This scenario, however, changes after a 40 min irradiation where large rectangular shaped dots of about 100 nm diameters and 40 nm height are observed. Surprisingly, for larger irradiation times a reduction in the size and heights is observed. The studies suggest “Critical Time” tc at t= 40 min such that the dot structures grow with time below tc but diminish in size beyond it.
Controlled Growth of Conducting Carbon Nanowires by Ion Irradiation: Electrical and Field Emission properties
Authors: Kumar Amit , Filip L D , Carey J. D. , Pivin J. C. , Tripathi A. , Avasthi D. K.
Published: April 2011

The conducting carbon nanowires embedded in fullerene matrix are synthesized by high energy heavy ion irradiation of thin fullerene film. We report the control growth of carbon nanowires, their electrical and field emission properties. The typical diameter of the conducting tracks is observed to be about 40 to 100 nm. The conductivity of the conducting zone is about seven orders of magnitude higher than that of the fullerene matrix. Conducting atomic force microscopy evidences the conducting nano wires. All the nanowires are parallel to each other and are perpendicular to the substrate. The density (spacing), growth direction and length of these carbon nanowires simply can be changed by ion fluence, angle of irradiation and the film thickness, respectively. The field emission measurements on these nanowires reveal that the threshold voltage is about ( ~13 V/mm), whereas the as deposited fullerene films shows a break down at ( ~ 51 V/mm). The present approach of making controlled conducting carbon nanowires is quite promising, as it takes few seconds of ion irradiation and no catalyst is required.
Pulsed Low-energy Ion-beam Induced Nucleation and Growth of Ge Nanocrystals on SiO2
Authors: Dvurechenskii Anatoly , Stepina Nataly , Novikov Pavel , Armbrister Vladislav , Kesler Valery , Gutakovskii Anton , Kirienko Victor , Smagina Zhanna , Groetzschel Reiner
Published: April 2011

Pulsed low-energy (200 eV) ion-beam-induced nucleation during Ge deposition on thin SiO2 film was used to form dense homogeneous arrays of Ge nanocrystals. The ion-beam action is shown to stimulate the nucleation of Ge nanocrystals when being applied after thin Ge layer deposition. Temperature and flux variation was used to optimize the nanocrystal size and array density required for memory device. Kinetic Monte Carlo simulation shows that ion impacts open an additional channel of atom displacement from a nanocrystal onto SiO2 surface. This results both in decrease of the average nanocrystal size and in increase of nanocrystal density.
Fabrication of Nanoscale Gold Clusters by Low Energy Ion Irradiation
Authors: Abidzina Volha , Tereshko I. , Elkin I. , Red'ko V. , Budak S. , Muntele C. , Walker D. , Ila D.
Published: April 2011

This work is focused on nanoscale gold particle formation by low-energy ion irradiation in glow-discharge plasma and studying particle growth by increasing time of exposure.

SiO2+Au films on SiO2 substrates produced by ion beam assisted deposition (IBAD) were exposed to ion irradiation at 1.2 keV energy for 1-2 hours. Plasmon resonance appearance caused by nanoparticle formation was observed by Optical Absorption Spectrometry (OAS).
Properties of Nano-layers of Nanoclusters of Ag in SiO2 Host produced by MeV Si ion bombardment
Authors: Smith C.C. , Budak S. , Guner S. , Muntele C. , Minamisawa R. A. , Zimmerman R. L. , ILA D.
Published: April 2011

We prepared 50 periodic nano-layers of SiO2/AgxSiO2(1-x). The deposited multi-layer films have a periodic structure consisting of alternating layers where each layer is between 1-10 nm thick. The purpose of this research is to generate nanolayers of nanocrystals of Ag with SiO2 as host and as buffer layer using a combination of co-deposition and MeV ion bombardment taking advantage of the electronics energy deposited in the MeV ion track due to ionization in order to nucleate nanoclusters. Our previous work showed that these nanoclusters have crystallinity similar to the bulk material. Nanocrystals of Ag in silica produce an optical absorption band at about 420 nm. Due to the interaction of nanocrystals between sequential nanolayers there is widening of the absorption band. The electrical and thermal properties of the layered structures were studied before and after 5 MeV Si ions bombardment at various fluences to form nanocrystals in layers of SiO2 containing few percent of Ag. Rutherford Backscattering Spectrometry (RBS) was used to monitor the stoichiometry before and after MeV bombardments.
Molecular Dynamics Simulations of Diffusive-Ballistic Heat Conduction in Carbon Nanotubes
Authors: Shiomi Junichiro , Maruyama Shigeo
Published: April 2011

Heat conduction of finite-length single-walled carbon nanotubes (SWNTs) has been studied by means of non-equilibrium molecular dynamics (MD) simulations. The length-dependence of the thermal conductivity was quantified for a range of nanotube-lengths at room temperature. The length dependence of thermal conductivity exhibits a gradual transition from nearly pure ballistic heat conduction to diffusive-ballistic heat conduction. The results show that the thermal conductivity profile does not converge even beyond a micrometer nanotube-length. Furthermore, the diameter dependence suggests that the phonon diffusion is reduced with the diameter.
Hydrogen Purification using Ultra-Thin Palladium Films Supported on Porous Anodic Alumina Membranes
Authors: Kirchner Alexander , Brown Ian W.M. , Bowden Mark E. , Kemmitt Tim
Published: April 2011

Nanostructured anodic alumina membranes have been utilized as high-temperature stable supports for 150 nm thick continuous palladium films. The palladium has been deposited by vacuum evaporation onto the rotating substrate. The thermal stability of the resulting compound membranes has been demonstrated for temperatures up to 700ºC under a reducing atmosphere. Hydrogen permeation has been measured up to 280ºC, where the permeability has a value of 2.5·10-7mol m-2s-1Pa-1. At the same time the selectivity factor over carbon dioxide is at least 33.
EBL/NIL fabrication and characterization of interdigitated electrodes for potential application in combinatorial studies.
Authors: Skjolding Lars Henrik Dæhli , Spégel Christer , Emnéus Jenny , Montelius Lars
Published: April 2011

Electrochemical transducers are frequently used to electrochemically deposit, synthesize and/or sense chemical compounds in material science, chemistry and biology. Traditionally this is done in fairly large volumes; generally several milliliters to even full production scale tanks, however, for high throughput measurements and combinatorial experiments smaller volumes are generally preferred. To probe small volumes small electrodes with preferable high density are needed. Presented in this paper is how to fabricate interdigitated electrodes by electron beam lithography (EBL) and also how to make large quantities by nanoimprint lithography (NIL) to enable combinatorial studies of cells or materials in microsystems (Lab-on-a-Chip Systems).

Interdigitated electrodes are shown to have additional advantages compared to simple disk or rod electrodes, such as being able to perform redox cycling experiments. The collection efficiency for the electrodes with pitch of 400 nm and width of 200 nm fabricated by EBL has been found to be round 87% when characterized electrochemically using ferro-/ferricyanide. The shape of the cyclic voltammograms for the electrodes are also in good agreement with the theoretical expectations for ultramicroelectrodes. Hence, these electrodes should be ideal candidates for combinatorial and high-throughput studies based on electrochemical methods.

Furthermore, a fabrication process based on nanoimprint lithography (NIL) is demonstrated, this could potentially ease fabrication and reduce cost of devices. The NIL process is based on thermal imprinting in PMMA 950k and LOR 0.7A.
ITO-Nanocomposite Thin Film Strain Gages with Low TCR
Authors: Chen Ximing , Chen Ximing
Published: April 2011

Dynamic strain gages based on alloys of indium tin oxide (ITO) have been developed to monitor the structural integrity of gas turbine engine components operating at temperatures in excess of 1200 °C. Static strain measurements in these harsh environments have been hampered by apparent strain effects that can be mitigated by employing sensors with a low temperature coefficient of resistance (TCR). Since refractory metals typically exhibit a positive TCR and semiconductors such as ITO exhibit a negative TCR, an optimal combination of materials could produce a sensor with little or no apparent strain. These materials were combined in a single strain gage element, in which phase separation occurred at very small length scales. Specifically, nanocomposite strain elements comprised of ITO/(Pt, Pd, W, NiCoCrAlY, Ni and Ir) combinatorial libraries were prepared by co-sputtering from ITO and refractory metal targets onto alumina constant strain beams. TCR was measured from room temperature to 1100 °C and the piezoresistive response of the more promising combinations was measured at strain levels approaching 1000 μm/m and the chemical composition of the most promising combinatorial libraries was analyzed by SEM/EDS. Preliminary results indicated that a strain gage based on an ITO/platinum (12% ITO: 88% Pt) nanocomposite was fabricated with a near zero TCR over the temperature range 500-1100 °C. The gage factor of this nanocomposite remained unchanged (∼-26.0) compared to that of ITO and thus, it appears that a simple additive mixture rule does not apply here and that other physics are controlling the piezoresistive response in these materials.
Estimation of Magnetic Energy Distribution in Co84Cr16Ta4 Magnetic Thin Films from EFTEM
Authors: Al-Sharab Jafar F. , Wittig James E , Bentley James , Evans Neal , Bertero Gerardo , Yamashita Tom
Published: April 2011

Magnetic thin films of Co80Cr16Ta4 were sputtered onto identical CrMo seed-layers at −200 V bias and 3 different substrate temperatures (150, 200, and 250°C). Energy-filtered transmission electron microscopy (EFTEM) was performed to analyze Cr levels at the grain boundaries as well as inside the grains. These quantitative Cr measurements were used to estimate the local values of magnetocrystalline anisotropy (Ku) and, together with grain size distributions, calculate the product of Ku and the grain volume (KuV), a quantity which is a measure of thermal stability. The results show that the coercivity as well as the percentage of stable grains increased with increasing substrate temperature. The increase in the number of stable grains is produced by the enhancement in the Ku value from Cr depletion of the grain interiors and the magnetic decoupling between the grains from Cr grain boundary segregation.
Si Ultra Shallow Junctions Dopant Profiling with ADF-STEM
Authors: Parisini Andrea , Giubertoni D. , Bersani M. , Morandi V. , Merli P. G. , van den Berg J. A.
Published: April 2011

In this work, we show how the Z-contrast annular dark field scanning transmission electron microscopy technique can provide reliable dopant profiles in ultra shallow junctions in Si. Dopant profiles obtained with this technique are compared with those obtained by spectroscopic techniques like secondary ion mass spectroscopy and medium energy ion scattering.
Lattice-Fringe Fingerprinting: Structural identification of nanocrystals by HRTEM
Authors: Peter Moeck , Bjorge Ruben
Published: April 2011

A novel method for the structurally identification of a nanocrystal from a single high resolution (HR) transmission electron microscopy (TEM) micrograph is described. Components of this method are demonstrated on both experimental and simulated HRTEM images. On the experimental side, the structural information that can be extracted from a HRTEM image is the projected reciprocal lattice geometry, the plane symmetry group, a few structure factor amplitudes and phases, and an outline of the projected atomic structure to the limited resolution of the HRTEM (via a Fourier synthesis of the structure factors). Searching for this information in a comprehensive database and matching it with high figures of merit to that of candidate structures should allow for highly discriminatory identifications of nanocrystals, even without additional chemical information as obtainable in analytical TEMs.
Strain measurements in s-Si/SiGe nanostructures by quantitative high-resolution electron microscopy
Authors: Hüe Florian , Hÿtch Martin , Bender Hugo , Hartmann Jean-Michel , Claverie Alain
Published: April 2011

We have studied strained Si layers grown on Si1-xGex virtual substrate (VS) by high-resolution transmission electron microscopy (HRTEM). Aberration-corrected HRTEM coupled with geometric phase analysis (GPA) provides precise measurements of strain. Different parameters are investigated: the VS composition (x=20, 30, 40 and 50%) and the s-Si layer thickness. Finite element method simulations confirm our measurements. Measurements and simulations lead to the conclusion that the strain state of the deposited layer is independent of the layer thickness. We apply the technique to measuring strains in the channel region of a p-MOSFET and show that the technique is a promising metrological tool for nanoelectronic devices.
Effect of Hydroxyl Group on the Characteristics of Solution Processed n- and p-type OFETs using Poly(p-silsesquioxane) Derivatives as a Gate Insulator
Authors: Ohmori Yutaka , Kajii Hirotake , Fukuda Shohei , Ogata Toshiyuki , Takahashi Motoki
Published: April 2011

Organic field effect transistors (OFETs) fabricated on the polymer substrate including conductive organic materials and polymeric gate insulator is one of promising devices for the flexible electronic devices. For OFETs with a conductive organic layer formed on the gate insulating materials, the performance of devices strongly depends on the molecular structure of the gate insulators. In this study, we investigated the effect of hydroxyl group of gate insulating materials on the characteristics of n- and p-type OFETs utilizing [6,6]-phenyl C61-butyric acid methyl ester (PCBM), α, ω-dihexylsexithiophene (DH6T) and pentacene OFETs as a conducting layer, respectively. Poly(p-silsesquioxane) (PSQ) derivatives are used as a polymeric gate insulator, which containes various ratios of phenol-group with a hydroxyl group bonded to a phenyl ring in the side chain of their molecular structures.
Surface Plasmon-mediated Luminescence in Organic Field-effect Transistors
Authors: Watanabe Akira , Tada Hirokazu
Published: April 2011

Considerable attention has recently been paid to light-emitting organic filed-effect transistors (LEOFETs) because of their potential applications to novel opto-electronic devices. In most LEOFETs, light emission occurs through the recombination of carriers injected from electrodes. Various efforts have been, thus, made to improve injection and transport properties of minority carriers in organic materials. On the other hand, light emission was frequently observed when we applied reverse bias voltages, that is, positive bias voltages, to the drain electrode for p-type FETs with grounded source and negatively biased gate electrodes. In this circuit, minority carriers were not injected into organic semiconductors. Nevertheless, the luminous intensity increased with drain voltage.

In the present work, we have prepared such novel type LEOFETs with various device structures. We have inserted thin metal wires between the source and drain electrodes in the channel region of pentacene FETs. It was found that the light emission was observed around the metal wires inserted and the luminous efficiency was improved with the number of wires. The luminescence spectrum was identical to that of pentacene films. The light emission was thought to be generated by via energy transfer to the pentacene films from plasmon excited on metal surfaces by current injection.
High-Performance Scan-Type Stage for Large Substrates
Authors: Takashi Ohno , Azuma K. , Mizutani T. , Kobayashi H.
Published: April 2011

Due to the steady increase in substrate sizes for low-temperature poly-Si devices and LSIs, there are strong demands for larger substrate handling, more accurate positioning and shorter tact time for many processes such as laser crystallization scan exposure, [3], and dopant activation [4] and so on. In order to satisfy such demands, we have developed a high-performance scan-type stage for large substrates. In this paper, we describe the outline of the mechanical structure and also the performance of this stage.

The XY moving stage was installed on an air slider of planarized granite. Stroke sizes of the stage were more than 920 mm and 730 mm for scan and step directions, respectively; the stage size was matched to the large glass substrates (4th generation). The stroke in the vertical direction was more than 32 mm, and the stage could rotate for more than ±0.3 degree for alignment.

The stage is driven by a newly introduced shaft-type linear motor, which consists of a fixed stainless-steel pipe shaft and a moving cylindrical coil rounded around the shaft. There are thin annular permanent magnets stacked inside the shaft. Since this coaxially aligned structure of permanent magnets and the coil is a nearly ideal configuration for efficient magnetic coupling, this motor could generate a stronger driving force; this enabled rapid acceleration and deceleration of the stage. Since stacked magnets generate parallel and uniform magnetic field along the shaft surface but slight field for transverse direction, electromagnetic force slightly fluctuated along the shaft, independent of the pitch of the magnet plate. This introduced another important advantage of the shaft-type linear motor that cogging, which has a serious impact on processing, was almost eliminated. This fluctuation was further reduced by introducing a real-time feedback system. The shaft-type motor, however, had been said to have the serious difficulty of elongation since its own weight bends the shaft. This problem was solved by using new magnetic materials and an optimized design of physical dimensions of the motor.

Experiments have been conducted under stabilized temperature conditions. The maximum scan speed of the stage was more than 500 mm/s with a speed stability of 0.03%, about one order of magnitude better than the reported value of about 0.5%. Acceleration and deceleration times from the halt condition to the constant velocity condition and vise versa were 1.0 s; the scan time was as short as 1.8 s for a 920 mm stroke. The “straight extent” was always better than ±0.5 mm Projection optics is commercially available for shaping a 30-mm-long excimer laser light beam on a sample surface. If we combine this stage and such optics, the whole area of a 4th-generation substrate surface can be scanned within a little more than 1 minute; that is, extremely high throughput can be expected. For example, to grow arrays of large Si grains, two-dimensional position control is the most important subject.