bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strain-Transfer Structure Beneath the Transistor Channel for Increasing the Strain Effects of Lattice-Mismatched Source and Drain Stressors
Authors: Yeo Yee-Chia , Ang Kah-Wee , Lin Jianqiang , Lam Chee-Shing 
Published: April 2011

AbstractWe incorporate an additional semiconductor heterostructure beneath the transistor channel region to increase the strain-transfer efficiency of lattice-mismatched source/drain (S/D) stressors, resulting in higher strain levels in the channel region. The additional structure is lattice-mismatched with respect to the overlying Si-channel and/or with respect to the S/D stressors. For an n-FET with Si:C S/D, a SiGe region integrated beneath the Si-channel enhances the magnitude of the tensile strain in the channel region. For a p-FET with SiGe S/D, a Si:C region beneath the Si-channel enhances the strain effect in the channel region. This additional structure beneath the transistor channel is called a strain-transfer structure (STS). Extensive numerical simulations were performed using the finite element method to explain how the new strain-transfer structure works. Profiles of the various strain components in the transistor channel were obtained. Dependence of the strain effect on geometrical features of the new transistor structure will also be reported.
Nucleation Studies of HfO2 Thin Films Produced by Atomic Layer Deposition
Authors: Hackley Justin C. , Demaree J. Derek , Gougousi Theodosia 
Published: April 2011

AbstractA hot wall Atomic Layer Deposition (ALD) flow reactor equipped with a Quartz Crystal Microbalance (QCM) has been used for the deposition of HfO2 thin films with tetrakis (dimethylamino) hafnium (TDMAH) and H2O as precursors. HfO2 films were deposited on H-terminated Si and SC1 chemical oxide starting surfaces. Spectroscopic ellipsometry (SE) and QCM measurements confirm linear growth of the films at a substrate temperature of 275°C. FTIR spectra indicate the films are amorphous as-deposited. Two distinct growth regimes are observed: from 1-50 cycles, both surfaces display similar growth rates of about 1.0Å/cycle; from 50-200 cycles, HfO2 growth is decreased by about 15% to ~0.87Å/cycle on both surfaces. Nucleation and initial growth behavior of the films on Si-H were examined using X-ray photoelectron spectroscopy (XPS). Angle-resolved XPS, at take-off angles of θ=0, 15, 30, 45 and 60° measured from the normal to the sample surface, is used to probe the interfacial region of thin films (4, 7, 10, 15 and 25 cycles) on H-terminated samples. Initially, an interfacial layer comprised of a SiOx/HfSiOx mixture is grown between 1-10 ALD cycles. We observe that the Si/HfO2 interface is unstable, and oxidation continues up to the 25th ALD cycle, reaching a thickness of ~18Å.
A New 3D Multistring Code to Identify Compound Oxide Nanophase With Ion Channeling
Authors: Bradley James Douglas , Herbots Nicole , Culbertson Robert , Shaw Justin , Atluri Vasu 
Published: April 2011

AbstractA new 3DMultiString computer code of Ion Beam Analysis (IBA) using 4He++ ion channeling combined with Nuclear Resonance Analysis (NRA) is used to analyze controlled formation of order in continuous layers of silicon dioxide nucleated on (1×1) Si(100) via the Herbots-Atluri clean (U.S. patent 6,613,677 (9/3/2003)) in air at 300 K. In our most recent work, this new 3DMultiString simulations combined with IBA leads to the identification of a new two-dimensional nanophase of tetragonally distorted β-cristobalite SiO2 (annotated b-c SiO2) with a critical thickness of 2 nm from the (1×1) Si (100)/b-c SiO2 interface to the b-c SiO2 /amorphous SiO2 interface (annotated b-c SiO2/a-SiO2). 3DMultiString simulations of IBA data taken on this new b-c SiO2/(1×1) Si(100) interphase includes channeling along the three <100>, <110>, and <111> axes of Si (100) in combination 16OO(α, α)16O 3.045 MeV NRA to measure oxygen areal densities corresponding to nm-thick films. In this way, the critical thickness of the β-c SiO2 nanophase can be established as a function of oxygen coverage. This new 3DMultiSTRING computer code is derived from the original 3DSTRING program that originated at Bell Labs, NJ.
Electrical Characterization of High-k Dielectrics by Means of Flat-Band Voltage Transient Recording
Authors: Duenas Salvador , Castán Helena , García Héctor , Bailón Luis , Kukli Kaupo , Ritala Mikko , Leskela Markus 
Published: April 2011

AbstractWe have carried out a comparison between flat-band transients displayed in metal-oxide-semiconductor (MOS) structures fabricated on several atomic layer deposited (ALD) high-k dielectric films: HfO2, ZrO2, Al2O3, Ta2O5, TiO2, and Gd2O3. The gate voltage as a function of time is recorded while keeping constant the capacitance at the initial flat band condition (CFB). Since samples are in darkness, under no electric fields and no charge-injection conditions, transients must be due to charge trapping of localized states produced by electrons (holes) coming from the semiconductor by tunnelling. The process is assisted by phonons and it is therefore thermally activated. The temperature-transient amplitude relation follows an Arrhenius plot which provides the thermal activation energy of soft-optical phonons. Finally, we describe the dependencies of the flat-band voltage on the setup bias history (accumulation or inversion) and the hysteresis sign (clockwise or counter-clockwise) of the capacitance-voltage (C-V) characteristics of MOS structures.
The Fine Structure of the Mn Distribution in ZnO Layers Deposited by Magnetron Sputtering for Spintronic Application
Authors: Abouzaid Morad , Ruterana Pierre 
Published: April 2011

AbstractIn this work, we carry out structural analysis of ferromagnetic Mn-doped ZnO thin films deposited by radio frequency magnetron sputtering, using transmission electron microscopy (TEM) and high resolution x-ray diffraction. On top of sapphire (0001) substrates, Mn rich precipitates and an interface reaction layer are observed following the deposition of Zn(Mn)O layers above 500°C. The crystalline quality of ZnO layers deposited by magnetron sputtering is highly improved at 500°C as well as the measured ferromagnetic response.
Micro/Nanofabrication by Spin Dewetting on a Poly(Dimethylsiloxane) Mold
Authors: Ferrell Nicholas , Bross Aimee , Hansford Derek 
Published: April 2011

ABSTRACTThe process of spin dewetting was used to fabricate polymer micro and nanostructures from poly(methyl methacrylate) (PMMA), poly (propyl methacrylate) (PPMA), and polystyrene (PS). Polymer structures were formed on poly(dimethylsiloxane) (PDMS) molds by dewetting of a polymer solution during spin coating. Features were removed from the mold using heat and pressure to transfer the polymer to silicon or glass substrates. By varying the coating conditions, a variety of different polymer feature morphologies were obtained for a given PDMS mold geometry. In this study, the ability to fabrication polymer micro and nanostructures using spin dewetting was demonstrated on a variety of PDMS mold geometries. The effects of polymer solution concentration and mold feature size on the resulting polymer structures were examined. In addition, microfabricated PMMA structures were used as etch masks for anisotropic etching of silicon in an aqueous solution of tetramethylammonium hydroxide (TMAH).
Modeling of Self-Assembly Dynamics of Photolithographically Patterned MUFFINS Biosensor Arrays
Authors: Lee Saul , Carmichael Peter , Meiring Jason , Dickey Michael , Grayson Scott , Bonnecaze Roger T. , Willson C. Grant 
Published: April 2011

ABSTRACTThe ability to mass produce biosensor arrays at low costs is an important target for the diagnostics industry. Our group has previously explored the batch production of mesoscale sized hydrogels as platforms for biosensors using photolithographic techniques. The individual hydrogel features were self-assembled through lateral capillary interactions to form a closed packed configuration and the pre-polymer medium was subsequently UV-cured to form the array. To understand the self-assembly dynamics, we investigated, through simulation, the flotation behavior of two assembling particles and its dependence on physical constants such as surface tension and particle density. Simulation results revealed that the objects tilt toward each other as they came into proximity. The tilt angle decreased with increasing surface tension but increased with increasing particle density. Understanding the details of the flotation behavior is necessary in the development of a full scale self-assembly model.
In-plane Molecular Alignment in Thin Films of Pentacene Grown by Solution Casting and Performance of Thin Film Transistors
Authors: Minakata Takashi , Nastume Yutaka 
Published: April 2011

AbstractWe have fabricated solution-processed thin films of pentacene by casting solution on a substrate and vaporizing solvent. The films with large oriented platelet domains were obtained by directionally grown condition. Molecular alignment in the directionally grown grains has been studied by several kinds of structural analysis. Oriented domains with the width of several hundreds microns and the length in an order of cm of the films were confirmed by polarized microscopy. In-plane crystalline structure of the domain has been studied by grazing incidence X-ray diffraction (GIXD) and strong anisotropy of in-plane crystalline structure was confirmed. Crystalline growth direction of the film was determined to be b-axis from both transmission electron diffraction and GIXD. Thin films transistors (TFTs) with directionally oriented domains of the films were fabricated on electrode patterned substrate. The observed maximum carrier mobility of 2.7 cm2/Vs was comparable to that of single crystal, which indicated that the quality of the film was almost identical with the single crystal. Correlation between FET performance and growth direction was studied and preferred performance of TFTs with the film grown perpendicularly to the channel was observed.
Fast Photoresponse of Functionalized Pentacene and Anthradithiophene Thin Films
Authors: Day Jonathan , Ostroverkhova Oksana , Anthony John 
Published: April 2011

AbstractWe present photoconductivity of high-performance functionalized pentacene and anthradithiophene thin films on time scales from picoseconds to many seconds after photoexcitation. The polycrystalline thin films were deposited from solution on glass substrates with patterned interdigitated aluminum electrodes. In studies of fast transient photoconductivity, the samples were excited with laser pulses of ~100 fs duration at a wavelength of 400 nm, and the photocurrent due to transport of photoexcited charge carriers was monitored using 50 GHz digital sampling oscilloscope. The photoconductivity at longer (milliseconds through seconds) time scales was investigated using continuous wave (cw) illumination and a source-delay-measure unit. Both experiments were performed under conditions of varied electric field strength, fluence and temperature. In all samples, we observed fast charge carrier photogeneration (<30 ps, limited by time resolution of our setup) followed by decay of the photocurrent over the period of 5-50 ns, depending on the material, due to charge trapping and recombination, linear dependence of the peak photoconductivity on the fluence and super-linear dependence of the peak photocurrent on the applied electric field.
A Planar Electroosmotic Micropump for Lab-on-Microchip Applications
Authors: Seibel Konstantin , Schöler Lars , Schäfer Heiko , Walder Marcus , Böhm Markus 
Published: April 2011

AbstractThe scope of the paper is to provide a theoretical and experimental treatment allowing to optimize critical design parameters for planar electroosmotic micropumps. The suggested design with a vertical arrangement of multiple narrow polymer pumping microchannels reduces the pump area to 1/10 compared to planar micropumps with widened shallow pumping channels. This design allows the fabrication of the channel system in only one process step, compatible with post-CMOS processing and suitable for monolithical integration on labchips. A simple analytical model has been developed to characterize the flow rate in a field free pressure-driven section of the channel. It is shown that the micropump with optimized dimensions of rib structures makes possible high pressure low voltage pumping. For high pressure capacity the distance between the ribs must be on the order of 0.5-1 µm with an aspect ratio of 10-20. The electroosmotic micropump with microchannels of SU-8 and polyacrylamide gel electrodes has been fabricated and tested. The pumping rate is bidirectionally linear and reached 10 nl/min at applied voltage of 40 V in 1 cm long pressure-driven channel, which corresponds to zero-flow pressure of 65 Pa.
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

AbstractThe 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

AbstractWe 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

AbstractThis 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

ABSTRACTHigh 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

ABSTRACTIn 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

ABSTRACTHybrid 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

ABSTRACTHierarchically 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

ABSTRACTA 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.