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Nm Thick (nm + thick)
Terms modified by Nm Thick Selected AbstractsVoltammetric Elucidation of Ion Transfer Through an Extremely Thin MembraneELECTROANALYSIS, Issue 9 2004Nobuyuki Ichieda Abstract Digital simulation of the cyclic voltammogram for the ion transfer through a liquid membrane of thickness from 1,mm to 10,nm was performed. The magnitude of current and the shape of the voltammogram simulated for extremely thin membrane (10,nm thick) were similar to those observed experimentally with a bilayer lipid membrane, BLM, of about 10,nm in thick, when the diffusion coefficient of an ion in the BLM was assumed to be extraordinary small (10,13 to 10,14,cm2 s,1). [source] Confinement effects on the morphology of photopatterned porous polymer monoliths for capillary and microchip electrophoresis of proteinsELECTROPHORESIS, Issue 14 2008Mei He Abstract We find that the morphology of porous polymer monoliths photopatterned within capillaries and microchannels is substantially influenced by the dimensions of confinement. Porous polymer monoliths were prepared by UV-initiated free-radical polymerization using either the hydrophilic or hydrophobic monomers 2-hydroxyethyl methacrylate or butyl methacrylate, cross-linker ethylene dimethacrylate and different porogenic solvents to produce bulk pore diameters between 3.2 and 0.4,µm. The extent of deformation from the bulk porous structure under confinement strongly depends on the ratio of characteristic length of the confined space to the monolith pore size. The effects are similar in cylindrical capillaries and D-shaped microfluidic channels. Bulk-like porosity is observed for a confinement dimension to pore size ratio >10, and significant deviation is observed for a ratio <5. At the extreme limit of deformation a smooth polymer layer ,300 nm thick is formed on the surface of the capillary or microchannel. Surface tension or wetting also plays a role, with greater wetting enhancing deformation of the bulk structure. The films created by extreme deformation provide a rapid and effective strategy to create robust wall coatings, with the ability to photograft various surface chemistries onto the coating. This approach is demonstrated through cationic films used for electroosmotic flow control and neutral hydrophilic coatings for electrophoresis of proteins. [source] Interfacial Microstructure of Chromium Oxide Coatings,ADVANCED ENGINEERING MATERIALS, Issue 7 2007X. Pang This paper presents a study of chromium oxide coatings' interfacial microstructure and structural properties affecting coating performance. Amorphous chromium and chromium oxide layers about 100 nm thick were detected at the Cr/steel and the Cr/coating interfaces, providing a solution for depositing thicker mechanically stable coatings with improved hardness, smaller grain size, and smooth surface. [source] Tuning and Transcription of the Supramolecular Organization of a Fluorescent Silsesquioxane Precursor into Silica-Based Materials through Direct Photochemical Hydrolysis,Polycondensation and MicropatterningADVANCED FUNCTIONAL MATERIALS, Issue 3 2009Xavier Sallenave Abstract A new fluorescent silsequioxane precursor with tuned optical properties and controlled aggregation properties is designed. The two cyclohexyl moieties introduced in the molecular structure allow the formation of very good quality films. The J-aggregated structure is transcribed into the solid by photoacid-catalyzed hydrolysis,polycondensation. Aggregation of the chromophores is reduced and highly fluorescent materials are obtained. The photoacid generator lies on the surface of the homogeneous layer of the sol,gel precursor. This phase separation presents several advantages, including UV protection of the chromophore and easy removal of the PAG. The first example of chemical amplification in the photolithography of the conjugated silsesquioxane precursor is demonstrated. As hydrolysis,polycondensation could be achieved in a controlled way by UV exposure, chemically amplified photolithography is achieved by irradiating a composite film (,110,nm thick) on silicon wafer by using a copper TEM grid as shadow mask. The pattern is produced uniformly on a miscroscopic scale of 3,mm, the photopatterned pixels remaining highly fluorescent. The sizes of the photolithographed pixels correspond to the sizes of the rectangular holes of the 300,×,75 mesh grid (hole: 63,<$>,<$>m,×,204,<$>,<$>m). [source] Efficient Polymer Solar Cells with Thin Active Layers Based on Alternating Polyfluorene Copolymer/Fullerene Bulk HeterojunctionsADVANCED MATERIALS, Issue 42 2009Mei-Hsin Chen Efficient (4.5% power conversion efficiency) polymer solar cells based on an alternating polyfluorene copolymer are demonstrated. The highest internal quantum efficiency obtained was 87%. The semi-transparent active layer (only 47,nm thick) shows the uniqueness of polymer solar cells and their unconventional applications, such as translucent solar windows for buildings and automobiles. [source] Simple Fabrication of Antibody Microarrays on Nonfouling Polymer Brushes with Femtomolar Sensitivity for Protein Analytes in Serum and BloodADVANCED MATERIALS, Issue 19 2009Angus Hucknall A multianalyte antibody array that is spotted on a poly(oligo(ethylene glycol) methacrylate) brush 100,nm thick, grown on glass via surface-initiated atom transfer radical polymerization, has femtomolar limit-of-detection (LOD) of cytokines in serum and whole blood, and a dynamic range of six orders of magnitude for a range of protein analytes. [source] Charge-injection photogate pixel fabricated in CMOS silicon-on-insulator technologyINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 2 2009Daniel Durini Abstract Concept, theoretical analysis, and experimental results obtained from a charge-injection photogate (CI-PG) pixel detector fabricated in CMOS silicon-on-insulator (SOI) technology are presented. The charge collected in the photodetector during a certain charge collection (integration) time is injected into the substrate for readout. This readout principle presents a huge internal photocurrent amplification (,104) taking place in the photodetector, obtained through the ,time-compression' approach. Here, the readout circuitry is fabricated on highly doped, 200,nm thick, SOI film, while the photogate detector is fabricated on higher resistivity handle-wafer. The latter, together with the 30,V biasing possibilities, enhances the quantum efficiency of the pixel, especially for irradiations with wavelengths in the near-infra-red part of the spectra. Copyright © 2008 John Wiley & Sons, Ltd. [source] Epidermal differentiation in embryos of the tuatara Sphenodon punctatus (Reptilia, Sphenodontidae) in comparison with the epidermis of other reptilesJOURNAL OF ANATOMY, Issue 1 2007L. Alibardi Abstract Studying the epidermis in primitive reptiles can provide clues regarding evolution of the epidermis during land adaptation in vertebrates. With this aim, the development of the skin of the relatively primitive reptile Sphenodon punctatus in representative embryonic stages was studied by light and electron microscopy and compared with that of other reptiles previously studied. The dermis organizes into a superficial and deep portion when the epidermis starts to form the first layers. At embryonic stages comparable with those of lizards, only one layer of the inner periderm is formed beneath the outer periderm. This also occurs in lizards and snakes so far studied. The outer and inner periderm form the embryonic epidermis and accumulate thick, coarse filaments (25,30 nm thick) and sparse alpha-keratin filaments as in other reptiles. Beneath the embryonic epidermis an oberhautchen and beta-cells form small horny tips that represent overlapping borders along the margin of beta-cells that overlap other beta-cells (in a tile-like arrangement). The tips resemble those of agamine lizards but at a small scale, forming a lamellate-spinulated pattern as previously described in adult epidermis. The embryonic epidermis matures by the dispersion of coarse filaments among keratin at the end of embryonic development and is shed around hatching. The presence of these matrix organelles in the embryonic epidermis of this primitive reptile further indicates that amniote epidermis acquired interkeratin matrix proteins early for land adaptation. Unlike the condition in lizards and snakes, a shedding complex is not formed in the epidermis of embryonic S. punctatus that is like that of the adult. Therefore, as in chelonians and crocodilians, the epidermis of S. punctatus also represents an initial stage that preceded the evolution of the shedding complex for moulting. [source] Combining Ar ion milling with FIB lift-out techniques to prepare high quality site-specific TEM samplesJOURNAL OF MICROSCOPY, Issue 3 2004Z. HUANG Summary Focused ion beam (FIB) techniques can prepare site-specific transmission electron microscopy (TEM) cross-section samples very quickly but they suffer from beam damage by the high energy Ga+ ion beam. An amorphous layer about 20,30 nm thick on each side of the TEM lamella and the supporting carbon film makes FIB-prepared samples inferior to the traditional Ar+ thinned samples for some investigations such as high resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). We have developed techniques to combine broad argon ion milling with focused ion beam lift-out methods to prepare high-quality site-specific TEM cross-section samples. Site-specific TEM cross-sections were prepared by FIB and lifted out using a Narishige micromanipulator onto a half copper-grid coated with carbon film. Pt deposition by FIB was used to bond the lamellae to the Cu grid, then the coating carbon film was removed and the sample on the bare Cu grid was polished by the usual broad beam Ar+ milling. By doing so, the thickness of the surface amorphous layers is reduced substantially and the sample quality for TEM observation is as good as the traditional Ar+ milled samples. [source] The entrapment of corrosion products from CoCr implant alloys in the deposits of calcium phosphate: A comparison of serum, synovial fluid, albumin, EDTA, and waterJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 8 2006A. C. Lewis Abstract Physical wear of orthopedic implants is inevitable. CoCr alloy samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, foetal bovine serum (FBS), synovial fluid, albumin in phosphate-buffered saline (PBS), EDTA in PBS, and water were studied using X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The difference in the corrosive nature of human serum, water, albumin in PBS and synovial fluid after 5 days of immersion was highlighted by the oxide layer, which was respectively 15, 3.5, 1.5, and 1.5 nm thick. The thickness of an additional calcium phosphate deposit from human serum and synovial fluid was 40 and 2 nm, respectively. Co and Cr ions migrated from the bulk metal surface and were trapped in this deposit by the phosphate anion. This may account for the composition of wear debris from CoCr orthopedic implants, which is known to consist predominantly of hydroxy-phosphate compounds. Known components of synovial fluid including proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP), have been identified as possible causes for the lack of significant calcium phosphate deposition in this environment. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:1587,1596, 2006 [source] The Concept of a Low-Temperature Synthesis for Superparamagnetic BaFe12O19 ParticlesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2010Miha Drofenik Superparamagnetic Ba-hexaferrite, BaFe12O19, nanoparticles were prepared by reacting tetrahydroxoferrates (III), [Fe(OH)4],(aq), and barium ions, Ba2+(aq), in an autoclave in the presence of a high concentration of hydroxide ions OH,. The synthesis temperature was between 80° and 140°C. The size and the morphology of the synthesized nanoparticles were confirmed by transmission electron microscopy. The crystal structure of the nanoparticles was characterized by X-ray diffraction. The powders synthesized above 120°C exhibited a bimodal particle size distribution, while those synthesized below 120°C showed a monomodal particle size distribution. The field-cooled/zero-field-cooled magnetization measurements showed typical superparamagnetic behavior. The superparamagnetic nanoparticles synthesized below 100°C exhibited a disk-like shape, on average <10 nm wide and 3 nm thick, with a room-temperature magnetization of approximately 3 emu/g at 1 T. [source] Structural Analysis on Planar Defects Formed in WC Platelets in Ti-Doped WC,CoJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2006Sabine Lay Platelet-reinforced WC,Co alloys are processed by liquid-phase sintering from very fine-grained WC powders in the presence of small amounts of TiC. Large and flat WC grains develop in the material. The microstructure of these platelets is investigated by high-resolution electron microscopy in order to obtain information on their formation mechanism. Inside the grains, an extended defect parallel to the basal plane is observed. It can be described by a pair of stacking faults with a shear vector equal to 1/3 ,0-110, occurring in two successive (0001) planes. At the level of the faults, the plane spacing is slightly reduced. The defect area is similar to a thin cubic layer about 0.5 nm thick at the interior of the platelet. The enhanced grain growth of the platelets is likely related to the presence of the defect area. [source] Filtration Behavior of Nanoparticulate Ceria SlurriesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2002Astrid Dietrich The influence of poly(acrylic acid) (PAA) concentration and molecular weight on the filtration behavior of CeO2 slurries with 20 nm particle size was studied. Low-viscosity suspensions could be produced by adsorbing a monolayer of PAA that covered the nanoparticles. For all suspensions investigated, the cake permeability was lower than predicted by the Kozeny,Carman equation and decreased with increased filtration pressure because of the presence of a compressible PAA layer 3,5 nm thick on the surface of the particles. The permeability of the nanoparticulate cakes decreased with increased polymer addition because of clogging. [source] Y2O2S:Eu Red Phosphor Powders Coated with SilicaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2000Jau-Ho Jean Y2O2S:Eu red phosphor powders were coated with silica (SiO2), using sol,gel and heterocoagulation techniques. Phosphor powders were dispersed in ethanol with tetraethyl orthosilicate and water. Hydrochloric acid was used to catalyze the sol,gel reaction, and an amorphous film 10,20 nm thick was observed via transmission electron microscopy (TEM). Colloidal SiO2 powders 10,70 nm in size were used, and the SiO2 powder coating was made by controlling pH values in the range of 4.5,8, in which a negatively charged surface of SiO2 powder and a positively charged surface of red phosphor powder were formed. Then, SiO2 powders were adsorbed electrically onto the phosphor powder surface, as evidenced by TEM, dissolution, and zeta potential measurements. Chemical bonding in the coating was studied using electron spectroscopy for chemical analysis and Fourier transform infrared spectroscopy. [source] Analytical SuperSTEM for extraterrestrial materials researchMETEORITICS & PLANETARY SCIENCE, Issue 10 2009John P. Bradley The improved technical capabilities enable analyses previously not possible. Mineral structures can be directly imaged and analyzed with single-atomic-column resolution, liquids, and implanted gases can be detected, and UV-VIS optical properties can be measured. Detection limits for minor/trace elements in thin (<100 nm thick) specimens are improved such that quantitative measurements of some extend to the sub-500 ppm level. Electron energy-loss spectroscopy (EELS) can be carried out with 0.10,0.20 eV energy resolution and atomic-scale spatial resolution such that variations in oxidation state from one atomic column to another can be detected. Petrographic mapping is extended down to the atomic scale using energy-dispersive X-ray spectroscopy (EDS) and energy-filtered transmission electron microscopy (EFTEM) imaging. Technical capabilities and examples of the applications of SuperSTEM to extraterrestrial materials are presented, including the UV spectral properties and organic carbon K-edge fine structure of carbonaceous matter in interplanetary dust particles (IDPs), X-ray elemental maps showing the nanometer-scale distribution of carbon within GEMS (glass with embedded metal and sulfides), the first detection and quantification of trace Ti in GEMS using EDS, and detection of molecular H2O in vesicles and implanted H2 and He in irradiated mineral and glass grains. [source] Synthesis of dendrimer,carbon nanotube conjugatesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2008A. García Abstract We describe the coupling between Carbon Nanotubes (CNTs) and a second-generation cyanophenyl-based dendrimer. The goal of our work is the synthesis of highly functionalized CNTs without provoking damage to the conjugated ,-system. One approach is the attachment of dendrimers with a high density of functional groups to the CNTs. These groups serve as anchor points for further reactions. With this aim, we have carried out a primary modification on CNTs by the use of 1,3 dipolar cycloaddition reaction. We have employed Single Wall Carbon Nanotubes (SWNTs) as well as Multi Wall Carbon Nanotubes (MWNTs) obtaining 238 ,mol and 511 ,mol of pyrrolidine groups per gram, respectively. The amount of amino groups introduced in the system was measured by the Kaiser test as well as thermogravimetric analyses. As a second step, dendrimer incorporation was performed by carbodiimide chemistry. Thermogravimetric Analysis, Raman Spectroscopy and Atomic Force Microscopy characterization techniques are reported for the characterization of the final CNT,dendrimer conjugate. The results show that the dendrimer has been attached covalently to the previously generated amine groups. Morphologically, the attached dendrimer with an estimated theoretical molecular length of 6.4 nm, generates a wrapping of 8 nm thick around the CNTs walls. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Interface of atomic layer deposited Al2O3 on H-terminated siliconPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2006K. Y. Gao Abstract Al2O3 films 1 to 20 nm thick were deposited as alternative high-, gate dielectric on hydrogen-terminated silicon by Atomic Layer Deposition (ALD) and characterized by Synchrotron X-ray Photoelectron Spec-troscopy (SXPS), Fourier Transform Infrared (FTIR) absorption spectroscopy and admittance measure-ments. The SXPS results indicate that about 60% of the original Si,H surface bonds are preserved at the Al2O3/Si interface and this is confirmed by monitoring the Si,H stretching modes by FTIR spectroscopy in the Attenuated Total Reflection (ATR) mode both before and after ALD of Al2O3. The remaining 40% of Si,H bonds are replaced by Si,O bonds as verified by SXPS. In addition, a fraction of a monolayer of SiO2 forms on top of the Al2O3 dielectric during deposition. The presence of OH-groups at a level of 3% of the total oxygen content was detected throughout the Al2O3 layer through a chemically shifted O 1s component in SXPS. Admittance measurements give a dielectric constant of 9.12, but a relatively high density of interface traps between 1011 and 1012 cm,2 eV,1. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Polycrystalline silicon thin films on glass obtained by nickel-induced crystallization of amorphous siliconPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010J. A. Schmidt Abstract In this work, we use the nickel-induced crystallization process to crystallize a-Si:H thin films at temperatures compatible with the utilization of glass substrates. Hydrogenated amorphous silicon films are deposited on planar float glass (Schott AF37) by plasma-enhanced chemical vapour deposition. The films, between 400 and 1400 nm thick, are grown intrinsic, slightly p-doped (p - ) or with a combined structure of heavily p-doped / slightly p-doped (p+/p - ) layers. On these films we sputter nickel with concentrations between 2.5×1014 and 3×1015 at./cm2, and then we anneal the samples in a standard nitrogen-purged tube furnace. The process evolves through the formation of the nickel silicide NiSi2, which has a lattice constant very similar to that of c-Si and acts as a nucleation centre. As a result of this thermal treatment we obtain thin polycrystalline films with a grain size over 100 ,m. The high crystallinity of the samples is confirmed through optical and electron microscopy observations, X-rays diffraction and Raman spectroscopy. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] GaN-based deep green light emitting diodes on silicon-on-insulator substratesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009S. Tripathy Abstract We have demonstrated deep green InGaN/GaN light emitting diodes (LEDs) on 100 nm thick (111)-oriented silicon-on-insulator (SOI) substrate. The LED structures are grown by metalorganic chemical vapour deposition. High-resolution X-ray diffraction and transmission electron microscopy have been used to characterize the structural quality of the LED layers. The room temperature electroluminescence (EL) spectrum from these LEDs is dominated by multiple interference peaks associated with the reflectivity changes at the bottom Si/SiO2 interfaces beneath AlN buffer. The spectral intensity of the LEDs in the deep green region is higher due to the larger substrate reflectance at longer wavelengths. A greater modulation in the spectral fringes in the longer wavelength regions is due to the presence of Fabry-Perot modes. Such InGaN/GaN light emitting structures on reflective SOI may be useful for the realization of phosphor-free white LEDs. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Decorated vacancy clusters in Si and thin C films grown on Si studied by depth profiling positron annihilation spectroscopiesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2007R. S. Brusa Abstract The combined use of different depth profiling positron annihilation spectroscopies give insight on distribution, type and decoration of open-volume defects. Applications regarding defects produced in modified silicon and at the interface between deposited thin films and the silicon substrate are presented. The attention is focused on selected systems and situations potentially related to technological developments: a) identification of decorated vacancy clusters in silicon implanted by light-ion (He, He+H) and evolution of the clusters with the thermal treatments; b) release of compressive stress through vacancy-like defects formation at the interface during the growth of thin (10-200 nm thick) carbon films. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] TCOs for nip thin film silicon solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 3 2009T. Söderström Abstract Substrate configuration allows for the deposition of thin film silicon (Si) solar cells on non-transparent substrates such as plastic sheets or metallic foils. In this work, we develop processes compatible with low Tg plastics. The amorphous Si (a-Si:H) and microcrystalline Si (µc-Si:H) films are deposited by plasma enhanced chemical vapour deposition, at very high excitation frequencies (VHF-PECVD). We investigate the optical behaviour of single and triple junction devices prepared with different back and front contacts. The back contact consists either of a 2D periodic grid with moderate slope, or of low pressure CVD (LP-CVD) ZnO with random pyramids of various sizes. The front contacts are either a 70,nm thick, nominally flat ITO or a rough 2,µm thick LP-CVD ZnO. We observe that, for a-Si:H, the cell performance depends critically on the combination of thin flat or thick rough front TCOs and the back contact. Indeed, for a-Si:H, a thick LP-CVD ZnO front contact provides more light trapping on the 2D periodic substrate. Then, we investigate the influence of the thick and thin TCOs in conjunction with thick absorbers (µc-Si:H). Because of the different nature of the optical systems (thick against thin absorber layer), the antireflection effect of ITO becomes more effective and the structure with the flat TCO provides as much light trapping as the rough LP-CVD ZnO. Finally, the conformality of the layers is investigated and guidelines are given to understand the effectiveness of the light trapping in devices deposited on periodic gratings. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||