bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low Temperature Silicon Dioxide Thin Films Deposited Using Tetramethylsilane for Stress Control and Coverage Applications
Authors: Lin Xin , Fonash Stephen J. 
Published: April 2011

ABSTRACTLow temperature silicon dioxide thin films have been prepared by plasma-enhanced chemical vapor deposition (PECVD) using tetramethylsilane (TMS) as the silicon precursor at 100- 200°C in the pressure range of 2- 8 Torr. PECVD TMS oxide thin films deposited at these temperatures and pressures exhibit adjustable stress. The type of stress, including tensile stress, zero stress, and compressive stress, as well as the stress level can be tailored as desired by changing the deposition conditions and film thickness. In addition, the conformality of PECVD TMS oxide thin films varies significantly with the deposition conditions. It improves when the deposition pressure is raised and the substrate temperature is reduced. The mechanisms for the variations of stress and conformality with respect to deposition conditions are discussed in this study. The adjustable stress and conformality of the PECVD TMS oxide make it a promising material for many low temperature applications, such as inter-level dielectric, micro-electro-mechanical systems (MEMs), microfabrication, and large area electronics.
Self organized array of quantum nanostructures via a strain induced morphological instability
Authors: Montiel David , Müller Judith , Poiré Eugenia Corvera 
Published: April 2011

AbstractMotivated by the work of Li et al. [1], we have studied the strain induced morphological instability at the submonolayer coverage stage of heteroepitaxial growth on a vicinal substrate with regularly spaced steps. We have performed a linear stability analysis and determined for which conditions of coverage a flat front is unstable and for which conditions it is stable. For low coverages the instability will cause the front to break in an array of islands. Assuming that the fastest growing mode of the instability determines the properties of the array, we make an estimation of the islands sizes and aspect ratios as well as an estimation of the separation length between islands of the array formed when the dominant mechanism for transport of matter is diffusion of particles along the growing front. These estimations are given as functions of the terrace width and coverage. Since these ones are experimentally controllable parameters, our results could be used to tailor the spontaneous formation of quantum nanostructures.
Lateral Composition Modulation in Mixed Anion Short Period Superlattices
Authors: Dorin C. , Wauchope C. , Millunchick J. Mirecki 
Published: April 2011

AbstractIn this work, we demonstrate for the first time lateral composition modulation in GaAs/GaSb short period superlattices (SPS). Several different structures were investigated in order to study the role of Group V overpressure on the final composition and uniformity of the structure. Cross sectional transmission electron diffraction and xray diffraction reciprocal space maps reveal that the film is indeed phase separated. The composition modulation observed in these films is a result of the SPS growth and not due to spinodal decomposition, as evidenced by the fact that an alloy grown at the same conditions results in a homogeneous layer.
Strain Relaxation in SiGe Thin Films Studied by Low-Energy Electron Microscopy
Authors: Woll A.R. , Moran P. , Rehder E.M. , Yang B. , Kuech T.F. , Lagally M.G. 
Published: April 2011

AbstractWe demonstrate the use of low-energy electron microscopy (LEEM) as a tool for studying dis-location formation in low-Ge-content SiGe films on Si(001) and silicon-on-insulator. Compared to TEM, sample preparation for LEEM consists only of conventional surface cleaning. Yet, because of its sensitivity to local variations in surface strain on Si(001), LEEM can detect dislocations at the earliest stages of strain relaxation. In identically prepared SiGe films, the typical dislocation extends over the entire viewable region of several hundred microns in SiGe/Si, but is less than 100 microns in SiGe/SOI. In addition, dislocation cross-slip and threading segments are common in SiGe/SOI, but virtually non-existent in SiGe/Si. We have also observed dislocation formation in real-time during high temperature annealing. Preliminary results appear to demonstrate dislocation multiplication and blocking at a perpendicular glide plane. The applicability of LEEM to strain relaxation in other Si-based systems will be discussed.
Nucleation and dynamics of dislocations in mismatched heterostructures
Authors: Patriarca Marco , Kuronen Antti , Kaski Kimmo 
Published: April 2011

AbstractIn this paper we have investigated, through computer simulations, dislocation nucleation and dislocation dynamics in a heterostructure system with the lattice-mismatch interface, i.e. a system with internal strain. In particular, we have studied the dependence of the nucleation thresholds on the basic parameters of the crystals, such as the amount of mismatch and the system temperature. These studies have been carried out by using the simulation code with a graphical user interface developed at our laboratory. This on-line simulation system produces a real time interactive visualization of the 3-D Molecular Dynamics model. Furthermore, it detects the presence of dislocations and tracks them by an algorithm based on potential energy mapping.
X-ray Analysis of Si/Ge/Si(001) Heterolayer Structures Grown by Surfactant Mediated Epitaxy.
Authors: Tinkham Brad P. , Goodner Duane M. , Walko Donald A. , Bedzyk Michael J. 
Published: April 2011

AbstractX-ray diffraction and x-ray standing waves (XSW) have been used to investigate the quality of epitaxial ultra-thin Ge films grown on Si(001) with and without Te as a surfactant. The efficacy of Te as a surfactant in this application has been debated. We measured samples between 1 and 10 ML in thickness and our results clearly indicate that Ge films grown with Te are superior to those grown without Te. The coherent positions and coherent fract ons determined from XSW analysis agree well with those predicted by linear elasticity theory for Ge/Si(001). Furthermore, grazing incidence diffraction measurements (GIXD) suggests that 9 ML Ge grown on Si(001) with Te is strained in-plane while the same film grown without Te is relaxed.
A Multi-Component Model for the Growth and Relaxation of Epitaxial Thin Films
Authors: Gill Simon P.A. , Long Fei , Cocks Alan C.F. 
Published: April 2011

AbstractA variational approach to the modelling of growth and relaxation in elastically strained epitaxial thin films and islands is presented. The continuum model is derived for a twocomponent material system evolving via the kinetic mechanisms of evaporation/condensation and surface and lattice diffusion under the influence of elastic mismatch strain, surface tension and combinational phase energy. Phenomena such as surface segregation and interdiffusion between the film and the substrate are incorporated into the model. This approach is illustrated by a 2D simulation of the onset of instabilities during the growth of epitaxial thin films.
Quantum-dot Cellular Automata
Authors: Snider Gregory L. , Orlov Alexei O. , Kummamuru Ravi K. , Ramasubramaniam Rajagopal , Amlani Islamshah , Bernstein Gary H. , Lent Craig S. 
Published: April 2011

AbstractAn overview is given of the quantum-dot cellular automata (QCA) architecture, along with a summary of experimental demonstrations of QCA devices. QCA is a transistorless computation paradigm that can provide a solution to such challenging issues as device and power density. The basic building blocks of the QCA architecture, such as AND, OR gates and clocked cells have been demonstrated and will be presented here. The quantum dots used in the experiments to date are metal islands that are coupled by capacitors and tunnel junctions, and devices operate only at very low temperatures. For QCA to be used in practical devices, the operating temperature must be raised, and issues such as background charge must be addressed. An introduction will be given to these issues and possible solutions.
Processing and Characterization of Al2O3 and Al2O3 / Cu Alloy Composites
Authors: McCuiston R.C. , Danforth S.C. , Niesz D.E. 
Published: April 2011

ABSTRACTFused deposition of ceramics (FDC) has been used to fabricate macroscopically graded ceramic skeletons. These Al2O3 skeletons were subjected to binder removal and sintering treatments. The sintered skeletons were infiltrated with copper alloys. Both the skeletons and composites were characterized for micro and macrostructure using scanning electron microcopy. Potential applications for the macroscopically graded ceramic/metal composites focus primarily on impact.
Cell-by-Cell Construction of Living Tissue
Authors: Ringeisen Bradley R. , Kim Heungsoo , Young H. Daniel , Spargo Barry J. , Auyeung R.C.Y. , Wu Peter K. 
Published: April 2011

ABSTRACTThis paper outlines investigations into a potentially revolutionary approach to tissue engineering. Tissue is a complex three-dimensional structure that contains many different biomaterials such as cells, proteins, and extracellular matrix molecules that are ordered in a very precise way to serve specific functions. In order to replicate such complex structure, it is necessary to have a tool that could deposit all these materials in an accurate and controlled fashion. Most methods to fabricate living three-dimensional structures involve techniques to engineer biocompatible and biodegradable scaffolding, which is then seeded with living cells to form tissue. This scaffolding gives the tissue needed support, but the resulting tissue inherently has no microscopic cellular structure because cells are injected into the scaffolding where they adhere at random. We have developed a novel technique that actually engineers tissue, not scaffolding, that includes the mesoscopic cellular structure inherent in naturaltissues. This approach uses a laser-based rapid prototyping system known as matrix assisted pulsed laser evaporation direct write (MAPLE DW) to construct living tissue cell-by-cell. This manuscript details our efforts to rapidly and reproducibly fabricate complex 2D and 3D tissue structures with MAPLE-DW by placing different cells and biomaterials accurately and adherently on the mesoscopic scale
Damage Detectability on Aluminum Alloy Panels Under Composite Patching by Various NDT Techniques
Authors: Moropoulou Antonia , Kouloumbi Niki , Marioli-Riga Zaira P. , Avdelidis Nicolas P. , Pantazopoulou Paraskevi 
Published: April 2011

AbstractComposite patching method is widely applied for repair cases of metallic aircraft structures due to more efficient performance than conventional repairs. However, the detection of structures integrity under patch, during the service life of aircraft, by non-destructive means is considered of great importance. In the present study, different NDT techniques such as active infrared thermography, eddy currents and electrical impedance spectroscopy, were applied for the detection of simulated artificially introduced damages - notches, on the surface of aluminum aircraft skin panels, Al 2024-T3, under composite patching (carbon reinforced laminates). The detection sensitivity of each technique was investigated based on the relation between thickness of composite patch and specific parameters of each method aiming at the development of a reliable, for this purpose, quality inspection technique.
Improving GaAs Chip yield And Enhancing Reliability of GaAs Devices
Authors: Prasad Kanti 
Published: April 2011

AbstractThe purpose of this research is to improve GaAs yield and enhance the reliability of GaAs MMICs (Monolithic Microwave Integrated Circuits) by first understanding the physical mechanisms of GaAs, Ni,Au-Ge eutectic and Au alloying process. Ohmic ooze has been driving force for this research. Variety of innovative experiments has been designed, so that contact resistance may be guaranteed to be within the permissible range. This resulted into the development of analytical techniques to measure contact resistance to GaAs as a result of alloying process employing Ni,Au-Ge and Au.
Depth Dependence of Dopant Induced Features on The Si(100)2x1:H Surface and Its Application for Three Dimensional Dopant Profiling
Authors: Liu Lequn , Yu Jixin , Lyding Joseph W. 
Published: April 2011

AbstractThe lack of surface states within the band gap of the perfect Si(100)2x1:H surface opens the way to scanning tunneling microscopy studies of dopant atom sites in Si(100). In this paper, Boron and Arsenic induced features are studied by ultrahigh vacuum scanning tunneling microscopy. The values of their amplitudes naturally group such that several subsurface layers can be identified. This technique for producing atom-resolved three-dimensional maps of electrically active dopants in silicon may be a useful metric for characterizing dopant profiles in ultra-small electronic device structures.
Magnetic Force Microscopy Signatures of Defects in Current-carrying Lines
Authors: Yongsunthon Ruchirej , Williams Ellen D. , Stanishevsky Andrei , McCoy Jonathan , Pego Robert , Rous Philip J. , Peckerar Martin 
Published: April 2011

AbstractThe spatial variation of current density in lines with model void defects fabricated using Focused-ion Beam (FIB) milling has been investigated using Magnetic Force Microscopy (MFM). The model defects were designed to systematically simulate the natural void shapes that occur in electromigration failure of current-carrying lines. Inhomogenous current density around the defects manifests itself in the form of atypical asymmetry in the MFM signal near the defects. The extent of the asymmetry is greatly dependent upon the defect geometry. At current densities of 3-5×106 A/cm2, an asymmetry in the MFM signal is clearly visible around defects, such as a (1×1) μ,2 notch and a (1×9) μm2 45°-slanted slit, at the edge of a 10μm wide line. We present a survey of MFM images of various defect structures in current-carrying lines that perturb the homogenous current flow of a straight line.
Improvement of Characteristics in Highly Reliable thin Film Diode with Anodic Tantalum Pentoxide by Low Temperature Annealing Conditions
Authors: Lee Chan-Jae , Hong Sung-Jei , Park Sung-Kyu , Kim Yong-Hoon , Kwak Min-Gi , Kim Won-Keun , Han Jeong-In 
Published: April 2011

AbstractIn this study, the quality of thin film diode (TFD) as a switching device for active-matrix liquid-crystal-displays (AM-LCDs) was enhanced by low temperature annealing conditions with high reliability and good electrical properties. Device was composed with Ta as bottom electrode, anodic Ta2O5 as insulator layer and top electrode. Two types of material such as Ti and Cr were evaluated as a top electrode of the TFD device to optimize the symmetry of current-voltage characteristic curve, respectively. The annealing was done at low temperature conditions below 350°C. The low temperature annealing improved the TFD device with nearly perfect symmetry under high electric field.
The Structure and Electrical Properties of Polyaniline
Authors: Ou Runqing , Samuels Robert J. , Gerhardt Rosario A. 
Published: April 2011

AbstractThe anisotropic structure of EB polyaniline films cast from N, N'-Dimethylpropylene urea (DMPU) solution and stretched to different draw ratios was studied by infrared dichroism. The drawn films were doped with 1.0 M HCl and the electrical properties were studied by impedance spectroscopy. A new test fixture has been developed to measure the in-plane impedance of polymeric films. A Debye-like conductivity relaxation was observed for all the HCl-doped PANI samples. The conductivity along the stretch direction increases with molecular orientation. The in-plane conductivity is significantly higher than the through-plane conductivity.
Development of combinatorial PLD-STM system for the quick nano-fabrication and evaluation
Authors: Matsumoto Y. , Ohsawa T. , Takahashi R. , Koinuma H. 
Published: April 2011

AbstractA combinatorial PLD-STM system has been developed for quick nano-fabrication and evaluation of epitaxial thin films and catalysts. Through a gate valve, a combinatorial nano-materials library fabricated in a PLD chamber can be transferred to a surface analysis chamber equipped with LEED and STM. The LEED pattern and atomically resolved STM image for systematically varied samples in the library are measured by locating one sample to another at the electron beam and STM probe position. In this way, we have quickly elucidated the initial growth process of SrO on SrTiO3(001) as well as surface structures of transition metal deposited TiO2 anatase. The combinatorial PLD-STM system has been verified to be very efficient technique for the exploration and optimization of nano-materials.
Co-doping Approach for β-type ZnO with Combinatorial Laser MBE Method
Authors: Tsukazaki A. , Saito H. , Sumiya M. , Tamura K. , Fuke S. , Koinuma H. , Kawasaki M. 
Published: April 2011

AbstractWe show here three different ways of combinatorial experiments for achieving precise control of dopant concentration in ZnO thin films. Alternating ablation of highly pure single crystal target and ceramics target doped with concentrated Ga dopant yielded in a systematic control of Ga concentration with keeping minimal contamination of undesired impurity. Secondary ion mass spectroscopy for a stack of several ZnO films grown at different temperatures under a constant exposure of N radical gave us a systematic calibration curve for the N concentration. With using a special heating method to give a controlled temperature gradient on a substrate, we demonstrate that continuous spread of N concentration can be built in a film on a substrate with keeping constant Ga concentration. Such systematic experiments taking into account the “combinatorial” concept enable us to make ZnO films with controlled dopant concentrations.
High throughput characterization of magnetic semiconductor thin films with a scanning SQUID microscope
Authors: Fan X. J. , Murakami M. , Takahasi R. , Koida T. , Matsumoto Y. , Hasegawa T. , Fukumura T. , Kawasaki M. , Ahmet P. , Chikyow T. , Koinuma H. 
Published: April 2011

AbstractMagnetic properties of Co-doped rutile (Ti1-xCoxO2) film in combinatorial composition-spread form have been surveyed by means of a Scanning Superconducting-quantum-interference-device Microscope (SSM). As a consequence, we found magnetic domains in the spatial regions with x>0.05 without external field, giving strong evidence for ferromagnetism with finite spontaneous magnetization. The magnetic moment was monotonously increased with increasing doping level x from 0.05 to ∼ 0.13. On the other hand, it was almost unchanged for x > ∼ 0.13, suggesting that Co does not dissolve into rutile film beyond x ∼ 0.13. The SSM results on the rutile Ti0.95Co0.05O2 thin films with different thickness showed that the magnetic moment is proportional to film thickness, leading to a conclusion that the presently observed ferromagnetism does not result from Co or Co-based oxide particles on the film surface.
Development of Functional Materials by a Composition Spread Approach
Authors: Cremer R. , Neuschütz D. 
Published: April 2011

AbstractIn this paper, the deposition and characterization of laterally graded materials libraries (composition spread) is presented. The films have been deposited by reactive magnetron sputtering, using two or three metallic targets at a low angle to the substrate surface as well as a system of apertures. To illustrate the advantages of combinatorial approaches for the development of advanced materials, the multicomponent metastable hard coatings (Ti,Al)N and (Ti,Al,Si)N were investigated with respect to the relations between structure and composition on the one hand and the oxidation resistance of these coatings on the other.
Growth Temperature and Oxygen Ambient Dependency of SrTiO3/Si(100) InterfaceStructures
Authors: Ahmet Parhat , Koida Takashi , Yoshimoto Mamoru , Koinuma Hideomi , Chikyow Toyohiro 
Published: April 2011

AbstractA systematical growth temperature and oxygen ambient dependency of SrTiO3/Si interface structures were investigated using a growth temperature gradient pulse laser deposition (PLD) system and cross sectional high resolution transmission electron microscopy (HRTEM). A SiO2 interfacial layer and an amorphized SrTiO3 layer were observed at the interface for the thin films grown on Si (100) at growth temperatures above 600°C. Our results show that at growth temperatures higher than 600°C, the formation of the amorphized SrTiO3 layer is strongly growth temperature and also oxygen partial pressure dependent.
Fabrication and characterization of in-situ grown epitaxial Ba1-xSrxTiO3 composition spreads
Authors: Chang K. S. , Aronova M. , Famodu O. , Hattrick-Simpers J. , Lofland S. E. , Takeuchi I. , Lu C. J. , Bendersky L. A. , Chang H. 
Published: April 2011

AbstractWe have used our combinatorial pulsed laser deposition system to in-situ fabricate epitaxial Ba1-xSrxTiO3 thin film composition spreads on (100) LaAlO3 substrates. Multimode quantitative microwave microscopy was used to perform dielectric characterization of the spreads at multiple microwave frequencies simultaneously. Systematic variation in dielectric properties as a function of composition is studied. The multi-mode measurements allow frequency dispersion studies. We observe strong composition-dependent dielectric dispersion in Ba1-xSrxTiO3.
Anomaly of Thermal Properties in Thin Films of La1-xSrxCoO3 Series Synthesized with a Combinatorial Processing
Authors: Takata Yoshiaki , Adachi Yutaka , Haneda Hajime , Wada Yoshiki , Ohtani Makoto , Fukumura Tomoteru , Kawasaki Masashi , Koinuma Hideomi 
Published: April 2011

AbstractThe thermal diffusivities throughout a composition-spread film comprising La1- xSrxCoO3 series were determined by Transient Reflecting Grating (TRG) measurements. Thermal diffusivities of transparent SrCoO3 film and SrTiO3 substrate were determined by using third harmonics having wavelength of 266 nm as an excitation light with only a certain length of grating spacing. The thermal diffusivities of them were 0.02 and 0.05 cm2/s, respectively. With regard to untransparent thin films, the experiment was performed by setting three kinds of grating spacing for the excitation light having the fundamental wavelength, 800 nm in order to obtain high precision. The distribution profile of obtained values of the thermal diffusivity throughout the sample was traced as 0.06 - 0.18 - 0.01 cm2/s corresponding to the variation of in La1-xSrxCoO3, thus showing a convex profile, however, this anomalous profile was verified by comparing with the data obtained by the X-ray diffractometer.