bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental and Theoretical Investigation into the Dielectric Behaviour of Ferroelectric Thin Film Superlattices
Authors: Gregg J. M. , O'Neill D. , Catalan G. , Bowman R. M. 
Published: April 2011

AbstractPulsed laser deposition has been used to fabricate thin-film capacitor structures in which the dielectric layer is composed of a superlattice of Ba0.8Sr0.2TiO3 and Ba0.2Sr0.8TiO3. The properties of the capacitors were investigated as a function of superlattice periodicity. The dielectric constant was significantly enhanced, and temperature migration of the peak in dielectric constant as a function of frequency was observed, at stacking periodicities of a few unit cells. However, such ‘relaxor-like’ features were found to be associated with high dielectric loss. Analysis of the imaginary permittivity as a function of frequency showed that fine-scale superlattices conform to Maxwell-Wagner behaviour, indicating that the observed features may be an artefact of increased carrier mobility. Modelling showed that both dielectric enhancement and frequency relaxation could readily be reproduced by Maxwell-Wagner formalism.
Nanoscale Properties of SrBi2Ta2O9 Thin Films
Authors: Gruverman A. , Isobe C. , Tanaka M. 
Published: April 2011

AbstractPiezoresponse scanning force microscopy (PFM) was applied to study the nanoscale mechanism of retention loss in SrBi2Ta2O9 (SBT) thin films. Experiments were conducted by performing local polarization reversal within an individual grain with subsequent imaging of a resulting domain structure at different time intervals. The retention behavior of the films was studied as a function of switching conditions and electrode material. SFM was also used for nanoscale mapping of leakage current sites and investigation of electrical conduction mechanism at these sites. For the first time, the development of dielectric breakdown in SBT films was directly observed at nanoscale.
Surface Reaction Mechanisms in the Chemical Vapor Deposition of (Ba,Sr)TiO3 Films
Authors: Yamamuka M. , Kawahara T. , Tarutani M. , Horikawa T. , Oomori T. , Shibano T. 
Published: April 2011

AbstractSurface reaction mechanisms in the chemical vapor deposition of (Ba,Sr)TiO3 [BST] films were studied by investigating the effects of O2 gas and source supply ratios on the characteristics of atomic incorporation rates. The atomic incorporation rates of Ba, Sr, and Ti increased with increasing incident flux of each source material, and then the values of the atomic incorporation rates became saturated. The saturated values increased monotonously with increasing O2 gas flow rate, in a range where atomic incorporation reactions might be controlled by the kinetics on the film surface (kinetically limited). Accordingly, O2 gas may effect the behavior of film precursors on BST film growth surfaces. From this, we assumed a CVD model, where the precursors are transported onto the film surface and adsorbed on adsorptive sites, and where the O2 gas has an effect on the formation of the adsorptive sites. With this model, atomic incorporation rates and overall sticking coefficients for the CVD of BST films were numerically simulated, and were in good agreement with experimental results for several O2 flow rates and source supply ratios.
Composite BST/MgO thin films for microwave tunable devices
Authors: Rivkin T. V. , Perkins J. D. , Parilla P. A. , Ginley D. S. , Carlson C. M. , Sengupta L. C. , Chiu L. , Zhang X. , Zhu Y. , Sengupta S. 
Published: April 2011

ABSTRACTComposite thin films of 60 wt% Ba0.6Sr0.4TiO3 and 40 wt% MgO were produced by Pulsed Laser Deposition. The biaxial texture of the BST component on the MgO substrate has been established with XRD. All as-deposited films had an enlarged BST out-of-plane lattice parameter. A more relaxed lattice constant as well as higher degree of texture has been obtained in the films deposited at higher temperature and lower deposition rate. Post-deposition annealing in flowing oxygen results in a further relaxation and alignment of the BST lattice. The as-deposited films were not tunable at room temperature. The greatest dielectric tuning was achieved in films annealed at 1200 °C. The observed difference in tunability for the films annealed at different temperatures may result from a spatial redistribution of BST material on the substrate surface during annealing.
Effect of Laser Energy and Laser Pulses on the Microstructure, Composition and Properties of Barium Strontium Titanate Thin Films Synthesized by Pulsed Laser Deposition
Authors: Fountzoulas Costas G. , Demaree J. D. , Mcknight Steven H. 
Published: April 2011

ABSTRACTBarium strontium titanate (BSTO) films were synthesized by the pulsed laser deposition technique (PLD) on silicon substrates at room temperature. The thin films were synthesized at ambient temperature and 30 mT oxygen partial pressure, with 300, 400 and 500 mJ/cm2 laser fluence at 5, 10 and 20 pulses per second on silicon wafer substrates. All films were subsequently post-annealed at 750°C in a continuous oxygen stream. The microstructure, crystallinity and lattice constant of the BSTO films were studied with the aid of atomic force microscopy (FEM) and Glancing Angle X-ray Diffraction analysis (GAXRD). The hardness and modulus of elasticity of the films were studied with the aid of a nanohardness indenter. The film stoichiometry was determined with the aid of Rutherford Backscattering Spectrometry (RBS). The results of this research will be combined with the results of our previous work [1, 2] on the effect of substrate temperature and oxygen partial pressure on the microstructure and properties of the BSTO films in order to construct a structural zone model (SZM) of the BSTO films synthesized by PLD.
Adjustment of Membrane Stress Using Aluminum Oxide and Silicon Dioxide Multi Layer Structure
Authors: Kubo Ryuichi , Yoshino Yukio , Inoue Kazuhiro , Makino Takahiro , Arai Seiichi 
Published: April 2011

ABSTRACTRelaxation of internal stress for micro-electromechanical systems (MEMS) using SiO2 / Al2O3 / SiO2 membrane has been studied. The aluminum oxide thin films were formed by electron beam evaporation at room temperature. No peaks were observed in the X-ray diffraction pattern of the films. The ratio of Al and O in aluminum oxide was stoichiometric compared with Al2O3 target material. The internal stress was tensile at about 300-400 MPa. Bottom SiO2 thin film was formed by thermal oxidation and the top one by RF magnetron sputtering method. The internal stress of thermally oxidized SiO2 film was compressive at about 440 MPa, while that of the films deposited by sputtering, was compressive at about 100 MPa. The ratio of Si and O in each SiO2 thin films remained stoichiometric. The total stress of the membrane was controlled by optimizing the thickness of each film for relaxing the total stress of the membrane. The total stress of the membrane became almost zero under optimum conditions of SiO2 and Al2O3 films.
Processing of Thick Dielectric Films for Power MEMS: Stress and Fracture
Authors: Chen Kuo-Shen , Zhang Xin , Spearing S. Mark 
Published: April 2011

ABSTRACTThis paper presents residual stress characterization and fracture analysis of thick silane based PECVD oxide films. The motivation for this work is to elucidate the factors contributing to residual stress, deformation and fracture of oxide films so as to refine the fabrication process for power MEMS. It is shown that residual stress in oxide films strongly depended on thermal processing history. Dissolved gases were found to play an important role in governing intrinsic stress. The tendency to form cracks is a strong function of film thickness and annealing temperature. Mixed mode fracture mechanics was applied to predict critical cracking temperature, and there is a fairly good match between theoretical predictions and experimental observations.
Influence of γ- Irradiation on the Phase Structure of Yba 2Cu 3O7-x
Authors: Khidirov I. , Baktibaev K. , Gafurov U. 
Published: April 2011

ABSTRACTThe influence of γ - irradiation on the structure of both superconducting and non-superconducting non-stoichiometric ceramics YBa 2 Cu 3 O 7−x by the neutron diffraction method has been investigated.The results caused due to the γ-irradiation of a powder sample YBa2Cu3O6.98 in evacuated ampoule crystalline lattice distortion can manifest themselves when content of O atoms decreases up to (7-x ) 6,64. The O atoms move away from O(1) and O(4) position mainly during this process. The Meissner effect does not appear. The lattice parameters are changed in an irradiated non -stoichoimetric sample mainly due to arising radiation defects.
Crystal Growth of Bi2Sr2CaCu2Ox Superconductor by Zone Melting Technique
Authors: Iwamoto T. , Watauchi S. , Tanaka I. 
Published: April 2011

ABSTRACTWe attempted to grow single crystals of Bi2Sr2CaCu2Ox (Bi-2212) by Traveling Solvent Zone Melting (TSZM) technique using a gold crucible to stabilize the molten zone as well as to control the composition of Bi-2212 single crystals. As the results of crystal growth, chemical composition of the grown crystals was determined to be Bi: Sr: Ca: Cu = 1.97(4): 1.75(7): 0.88(3): 2.0, which was close to that of feeds. TSZM growth may be effective on the control of composition of Bi-2212 crystals. Superconducting properties of the grown crystal of Bi-2212 were TcTconset=85 K andΔTc=10 K.
Fabrication and Characterisation of Calcium Phosphate - Liposome Composites as an Implant Coating
Authors: Pongsaanutin Tarinee , Czernuszka Jan T. 
Published: April 2011

AbstractCalcium phosphate in the form of apatite has been successfully precipitated on the surface of liposomes. Liposome vesicles were prepared by sonication of phosphatidylcholine and this was introduced into an aqueous solution of calcium and phosphate ions supersaturated with respect to hydroxyapatite. Calcium phosphate was shown to precipitate solely on the outer layer surface of the liposome vesicles. These composite assemblies were then deposited onto a stainless steel cathode substrate using an electrophoretic method at physiological temperatures.Scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder xray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) were used to analyse the morphology, structure and chemical composition of the composite coating. The results from PXRD and FTIR show a mixture of amorphous and poor crystalline hydroxyapatite (HAp). This was verified by electron diffraction. Dark field images confirmed that the precipitated HAp deposited solely at the outer surface of the liposomes. SEM micrographs demonstrated a thin uniform coating at the microstructure level. These results suggest that these calcium phosphateliposome composites can be formed. They have tremendous potential for use as drug delivery devices in aiding the treatments of bone disorders.
Effects of Block Lengths and Initial Water Content on the Swelling and Degradative Characteristics of an Injectable Poly(propylene Fumarate-Co-Ethylene Glycol) Block Copolymer Hydrogel
Authors: Shung Albert K. , Mikos Antonios G. 
Published: April 2011

AbstractThe overall goal of this project is to develop an in-situ polymerizable, biodegradable material for use in cardiovascular applications that minimizes non-specific cell adhesion and contains functional moieties for the attachment of peptides to induce specific cell attachment. A novel block copolymer has been developed incorporating poly(propylene fumarate) (PPF) and poly(ethylene glycol) which satisfies these criteria. PPF is a new biodegradable polymer currently being investigated for orthopedic and cardiovascular applications while PEG is a hydrophilic polymer that has been extensively studied for biomedical applications. The copolymer is chemically crosslinked with PEG diacrylate using an ammonium persulfate-ascorbic acid redox initiator system to form the hydrogel. The PEG and PPF block lengths can be varied to modulate the properties of the hydrogel formed. In this study, the following three parameters were studied, (1) PPF block length, (2) PEG block length, and (3) initial water content, were varied to examine their effects on swelling, degradation and elastic modulus. A factorial experimental design was implemented to assess which of these three parameters had the greatest impact on swelling, degradation and elastic modulus. Swelling was found to be most affected by the initial water content followed by PEG block length and PPF block length. The swelling of the hydrogels ranged from 48% water uptake with low initial water content to up to 77% water uptake with the high initial water content. After three weeks, degradation of the hydrogels ranged from 4-13% mass fraction lost. Elastic modulus was determined by tensile testing of the various hydrogel formulations and ranged from 0.4 to 7.7 MPa.
Stress and Microstructure Evolution during the Deposition and Crystallization of DCMagnetron Sputter Deposited Amorphous ITO
Authors: Yeom Hyo-Young , Lanier Courtney , Chason Eric , Paine David C. 
Published: April 2011

ABSTRACTThe deposition of ITO onto glass substrates at room temperature results in a metastable amorphous phase that undergoes crystallization at remarkably low homologous temperatures (T/Tm<0.2). We have evaluated ITO film stress in the as-deposited condition and during crystallization of 200 nm thick films isothermally heated at 250°C. To explore the effect of stoichiometry on the amorphous structure, ITO films were deposited under low, optimum, and high (0, 0.1, and 2 vol %, respectively) oxygen partial pressures. In this report we have correlated changes in stress with changes in the electron transport characteristics (hall mobility and carrier density) and film microstructure.
Transparent P-type Conducting LaCuOS Layered Oxysulfide
Authors: Ueda Kazushige , Inoue Shin-ichiro , Hirose Sakyo , Kawazoe Hiroshi , Hosono Hideo 
Published: April 2011

ABSTRACTMaterials design for transparent p-type conducting oxides was extended to oxysulfide system. LaCuOS was selected as a candidate for a transparent p-type semiconductor. It was found that the electrical conductivity of LaCuOS was p-type and controllable from semiconducting to semi-metallic states by substituting Sr2+ for La3+. LaCuOS films showed high transparency in the visible region, and the bandgap estimated was approximately 3.1 eV. Moreover, it was revealed that LaCuOS showed sharp excitonic absorption and emission at the bandgap edge, which is advantageous for optical applications. A layered oxysulfide, LaCuOS, was proposed to be a promising material for optoelectronic devices.
Optical and Structural Properties of Zinc-oxide Thin Film Deposited by Pulsed Laser Deposition
Authors: Ohshima Tamiko , Thareja Raj K. , Yamagata Yukihiko , Ikegami Tomoaki , Ebihara Kenji 
Published: April 2011

ABSTRACTWe report optical and structural properties of ZnO films deposited by pulsed laser deposition technique on silicon (100) n-type, quartz, sapphire, and corning glass substrates. We have studied the influence of the deposition parameters, such as substrate temperature, oxygen pressure, and laser fluence on the properties of the grown films. Dependence of nanocrystallites on temperature of substrate and ambient gas pressure is investigated. ZnO plasma created at varying fluence of KrF laser (248 nm) on the target was investigated using optical emission spectroscopy and 2-d images of the expanding plumes at various pressures of the ambient gas. X-ray diffraction, atomic force microscopy, electron probe micro-analyzer, and spectro-photometry were used to characterize as grown films.
A New Kinetic Model for The Nucleation and Growth of Self-Interstitial Clusters in Silicon
Authors: Ortiz Christophe J. , Mathiot Daniel 
Published: April 2011

ABSTRACTA model for nucleation and growth of {311} defects is proposed on the basis of thermodynamic and kinetic considerations. Simulated results are discussed and compared to experimental results found in the literature. According to our model it is found that formation energies of self-interstitial clusters depends on the local interstitial supersaturation. Physical parameters extracted from experimental results by inverse modeling are in good agreement with recent values published in the literature.
Characterization and Control of Copper CMP with Optoacoustic Metrology
Authors: Gostein Michael , Lefevre Paul , Maznev Alex A. , Joffe Michael 
Published: April 2011

ABSTRACTWe discuss applications of optoacoustic film thickness metrology for characterization of copper chemical-mechanical polishing (CMP). We highlight areas where the use of optoacoustics for CMP characterization provides data complementary to that obtained by other techniques because of its ability to directly measure film thickness with high spatial resolution in a rapid, non-destructive manner. Examples considered include determination of planarization length, measurement of film thickness at intermediate stages of polish, and measurement of arrays of metal lines.
Environmentally-benign cleaning for giga DRAM using electrolyzed water
Authors: Ryoo Kunkul , Kang Byeongdoo 
Published: April 2011

ABSTRACTA present semiconductor cleaning technology is based upon RCA cleaning technology which consumes vast amounts of chemicals and ultra pure water(UPW) and is the high temperature process. Therefore, this technology gives rise to the many environmental issues, and some alternatives such as functional water cleaning are being studied. The electrolyzed water was generated by an electrolysis system which consists of anode, cathode, and middle chambers. Oxidative water and reductive water were obtained in anode and cathode chambers, respectively. In case of NH4Clelectrolyte, the oxidation-reduction potential and pH for anode water(AW) and cathode water(CW) were measured to be +1050mV and 4.8, and -750mV and 10.0, respectively. AW and CW were deteriorated after electrolyzed, but maintained their characteristics for more than 40 minutes sufficiently enough for cleaning. Their deterioration was correlated with CO2 concentration changes dissolved from air. It was known that AW was effective for Cu removal, while CW was more effective for Fe removal. The particle distributions after various particle removal processes maintained the same pattern. In this work, RCA consumed about 9 chemicals, while EW did only 400ml HCl electrolyte or 600ml NH4Cl electrolyte. It was hence concluded that EW cleaning technology would be very effective for eliminating environment, safety, and health(ESH) issues in the next generation semiconductor manufacturing.
Epitaxial growth and interface roughness of PdMn/Fe bilayer structures grown by ion-beam sputtering
Authors: Cheng Ning , Ahn J.P. , Grogger Werner , Krishnan Kannan 
Published: April 2011

ABSTRACTDifferent orientations of PdMn films and different stacking orders of PdMn and Fe on MgO(001) were studied. At low temperatures (T< 280°C) dominated by the kinetics of growth, a-axis orientated [PdMn(100)/Fe(001)/MgO(001)] was stabilized whilst c-axis [PdMn(001)/Fe(001)/MgO(001)] were obtained at higher temperatures (T> 300°C). The inverted structures, Fe(001)/PdMn(001)/MgO(001) and Fe(001)/PdMn(100)/MgO(001), were obtained epitaxially for the first time. The magnetic exchange coupling (He) of these PdMn/Fe bilayers show a wide range in values: ∼ 10 Oe for annealed a-axis samples, ∼ 33 Oe for c-axis normal samples and ∼ 68 Oe for c-axis inverted samples. The interface roughness of these samples was characterized by energy-filtered transmission electron microscopy (EFTEM). The orientation relationships were confirmed by x-ray diffraction and TEM. The possible origins for the He difference in a-axis and c-axis growth samples and the normal and inverted samples are discussed.
Properties of InGaN/GaN Quantum Wells Grown by Metalorganic Chemical Vapor Deposition
Authors: Cheong M. G. , Kim K. S. , Kim C. S. , Choi R. J. , Yoon H. S. , Yu S. W. , Hong Y. K. , Hong C.-H. , Suh E.-K. , Lee H. J. 
Published: April 2011

ABSTRACTOptical and structural properties of InGaN/GaN quantum wells having growth interruption were investigated using high-resolution x-ray diffraction, photoluminescence and transmission microscopy. InxGa1−xN/GaN (x>0.25) six pair quantum wells used in this study were grown on c- plane sapphire by metalorganic chemical vapor deposition. The growth interruption was carried out by closing the group-III metal organic sources before and after growth of InGaN quantum well layers. With increasing the interruption time, the quantum dot-like region and well thickness decreases due to indium re-evaporation or thermal etching effect. As a result, PL peak position is blue-shifted and intensity is reduced. The size and number of V-defect did not vary with interruption time. The interruption time is not directly related with formation of the defect. The V-defect in quantum wells originates at threading dislocations and inversion domain boundaries due to higher misfit strain.
Temperature and Coverage Dependence of the Surface Roughness for the Growth of Cu on Cu(001): An X-ray Scattering Study
Authors: Botez Cristian E. , Elliott William C. , Miceli Paul F. , Stephens Peter W. 
Published: April 2011

ABSTRACTSynchrotron X-ray scattering was used to study the temperature and coverage dependence of the root-mean-square (rms) surface roughness, σ, during the homoepitaxial growth on Cu(001). At temperatures between 370 and 160K, the rms roughness was found to increase as a power law, σ =Θβ, with the coverage Θ. The roughness exponent, β, amounts to ∼1/2 for T≤200K, and it monotonically decreases with increasing T, reaching β∼1/3 at T=370K. The mean-square roughness measured at a constant coverage of 15ML, σ2 15 ML, also depends on the temperature of the substrate: between 370 and 200K, σ2 15 ML becomes progressively larger at lower temperatures, but at 110K a reentrant smoother growth is observed.
Dynamics of the Euler Buckling Instability
Authors: Golubovic Leonardo 
Published: April 2011

ABSTRACTWe review recent systematic investigations of the dynamics of the classical Euler buckling of compressed solid membranes and thin sheets. We relate the membrane buckling dynamics to phase ordering phenomena. Evolving membranes develop wavelike patterns whose wavelength grows, via coarsening, as a power of time. We find that evolving membranes are similar to interfaces of thin films in molecular-beam epitaxy growth with slope selection: They are characterized by the presence of mounds whose typical size grows as a power of time. The morphologies of the evolving membranes are characterized by the presence of a network of growing ridges where the elastic energy is mostly concentrated. We used this fact to develop a scaling theory of the buckling dynamics that gives analytic estimates of the coarsening exponents. Our findings show that the membrane buckling dynamics is characterized by a distinct scaling behavior not found in other coarsening phenomena.
Heteroepitaxial Growth and Phase Transition Properties of Vanadium Dioxide Thin Films on Different Orientations of Sapphire Substrates
Authors: Wu Z.P. , Naramoto H. 
Published: April 2011

ABSTRACTVanadium dioxide thin films have been deposited on sapphire substrates with different orientations by pulsed laser ablation. The samples are analyzed by x-ray diffraction and pole figures to determine epitaxial relationship. The crystal quality is evaluated by RBS/Channeling techniques. The results has shown that the growth of VO2 is of strong substrate dependence, the film on (0001) sapphire substrate exhibits better crystal quality than that on (1120) and (0112) sapphire substrates. The epitaxy can be divided into two processes, the first is surface symmetry determined oriented growth, and the second is in-plane oriented growth dominated by the minimization of in-plane lattice mismatch. More over, different substrates result in different defect microstructures, 120o twin is observed in VO2 film on (0001) substrate while 180o on (1120) and no twin on (0112), which also reflects the surface symmetries of the substrates.