bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relaxation of Grain Boundaries in Au {110} Mazed Bicrystal Thin Films Observed by HREM
Authors: Radetic Tamara , Dahmen Ulrich 
Published: April 2011

ABSTRACTThin films of gold can be grown on {001} Ge single crystal substrates in two equivalent {110} orientation variants, related to each other by a 90° rotation about the surface normal. The morphology of the films is that of a mazed bicrystal, a polycrystalline film with many randomly distributed columnar grains in only two orientations. All grain boundaries are of the type S99 and display pure tilt character. In this work, we report on observations of the structural relaxation of these grain boundaries, with special emphasis on their characteristic behavior at the intersection with free surfaces and their evolution during thermal annealing.
Texture of Sputtered Thin Copper Films on Amorphous SiO2 and Si3N4 substrates.
Authors: Okolo Brando , Welzel Udo , Lamparter Peter , Wagner Thomas , Mittemeijer Eric J. 
Published: April 2011

ABSTRACTCu films with thickness of 500nm and 5nm have been sputter deposited on amorphous SiO2 and Si3N4 substrates without and after sputter cleaning. The crystallographic texture has been characterized by x-ray diffraction techniques. Sputter cleaning of the substrates, by which the oxygen contaminants are removed from the Si3N4 substrates, leads to an increase in the {111} texture strength and sharpness of the Cu films on Si3N4. The texture is sharper in the 500nm thick Cu films than in the 5nm thick films. Roughness differences of the substrate surfaces have no obvious effect on the texture state.
Relaxation of a Strained Elastic Film on a Viscous Layer
Authors: Huang R. , Yin H. , Liang J. , Hobart K. D. , Sturm J. C. , Suo Z. 
Published: April 2011

ABSTRACTExperiments were conducted with SiGe film islands on a layer of borophosphorosilicate glass (BPSG). Initially the SiGe is under compression. Upon annealing, the glass flows and the SiGe islands relax by both inplane expansion and wrinkling. This paper provides a two-dimensional (2D) model for inplane expansion. The results from the model are compared with the experiments with small SiGe islands. The effect of winkling, which is ignored in the present model, is discussed qualitatively.
Near-Edge X-ray Absorption Fine Structure of Hard Carbon Film Formed by Gas Cluster Ion Beam Assisted Deposition
Authors: Kanda Kazuhiro , Shimizugawa Yutaka , Haruyama Yuichi , Yamada Isao , Matsui Shinji , Kitagawa Teruyuki , Terasawa Mititaka , Tsubakino Harushige , Gejo Tatsuo , Kamada Masao 
Published: April 2011

ABSTRACTThe coordination of the carbon atoms in the diamond-like carbon (DLC) films formed by Ar gas cluster ion beam (GCIB) assisted deposition of fullerene was investigated using synchrotron radiation. Near-edge x-ray absorption fine structure (NEXAFS) spectra of the carbon K-edge of the DLC films formed by various methods were measured over the excitation energy range 275-320 eV, using synchrotron radiation. On the basis of the analysis of the peak corresponding the transition of the excitation electron from carbon 1s orbital to Φ orbital, relative sp2 contents of various DLC films were determined. The DLC films formed by Ar GCIB assisted fullerene deposition were found to consist of a high sp3 hybridized carbon.
Thin Film Characterization Using the Point-Deflection Method
Authors: Tang Ning , Engelstad Roxann L. , Lovell Edward G. 
Published: April 2011

ABSTRACTThe Point-Deflection Method is a potentially useful technique for measuring the internal stresses of freestanding thin films. By applying a small concentrated transverse load at the center of a pre-stretched film, and measuring the corresponding out-of-plane displacement at appropriate locations, the average internal stress can be readily determined. The load-deflection relationship has been derived for both circular and rectangular shapes. The method involves no additional micromachining in sample preparation and has low sensitivity to the variations in boundary constraints. Its feasibility has been further substantiated with finite element simulations from a variety of perspectives, as well as experimental correlations from the stress measurements of a photomask pellicle film.
A Method for Extracting Quantitative Data Duringin-situTEM Nanoindentation
Authors: Minor A.M. , Lilleodden E.T. , Stach E.A. , Morris J.W. 
Published: April 2011

ABSTRACTThe development of a novel transmission electron microscope holder has made real time observations of nanoindentation possible. Using a piezo-ceramic loading mechanism, a diamond indenter is pushed into the surface of a sample, while the electron beam images the deforming sample in cross section. In this paper, we present the method for calibrating the force-displacement-voltage relation and load-frame compliance associated with this instrument. This allows quantitative force-displacement measurements to be obtained, in the manner of traditional indentation experiments. As an example of the utility of this technique, we present observations of the indentation behavior of an Al thin film on silicon, which have been previously shown [1]. Indentation into a coarse grain shows a displacement excursion corresponding to the nucleation of dislocations, and is compared to force-displacement responses measured with instrumented indentation techniques.
Nano-Creep Test for Anatase Polycrystalline Films
Authors: Sugata Hironori , Ohshio Shigeo , Saitoh Hidetoshi 
Published: April 2011

ABSTRACTWe introduce an analytical technique for time-dependent deformation behavior of the polycrystalline films using a nano-indenter. This technique permits evaluation of structural deformation of the nanometer scale of the thin films. In this paper, good accuracy conditions were determined to measure deformation behavior of the polycrystalline films. The polycrystalline films of anatase were used to investigate the grain boundary structure. We prove that the analysis of time-dependent deformation behavior is effective to investigate the structure of the polycrystalline films.
Mechanistic Understanding of the Stress-Induced Failure of Si3N4 Metal-Insulator-Metal Capacitors
Authors: Suh Dongwoo , Mheen Bongki , Lee Seung-Yun , Shim Kyu-Hwan , Kang Jin-Yeong 
Published: April 2011

ABSTRACTThe failure of Si3N4 metal-insulator-metal (MIM) capacitors fabricated by plasma enhanced chemical vapor deposition (PECVD) was investigated using cross-sectional transmission electron microscopy (XTEM) and residual stress analysis. As a result we noted that the failure of the Si3N4 MIM capacitors originated from the microvoids formed over the Si3N4 dielectric and the TiN interlayer. The microvoid of the MIM capacitor, particularly in case of having a very thin Si3N4 of less than 50 nm-thick, caused it to leak out much of the current to the extent of a few microamperes even at bias of 3 volts. The formation of microvoids was explained by the residual stress of the constituent layers at a mechanistic point of view. The stress analysis showed that the absolute stress normalized by the thickness of the Si3N4 layer should be less than 31 MPa/nm to avoid microvoiding. In this research it was noted in conclusion that the stress state of not only the dielectric but also the interlayer should be taken into account for the successful design of high capacitive Si3N4 MIM capacitors.
Effects of Various Passivation Dielectrics and Via Reservoir Lengths on Stress and Electromigration Reliability of Metal Interconnects
Authors: Park Young-Bae , Cho Young-Ah , Lee Won-Gyu 
Published: April 2011

ABSTRACTReservoir length dependencies of electromigration lifetime in multilevel interconnect were compared for two passivation dielectrics, that is, FOX (Flowable Oxide) and HDP FSG (High Density Plasma Fluorinated Silicate Glass). The higher electromigration resistance of interconnects passivated by FOX can be best explained by their lower stress and vacancy concentration levels than the case for FSG. It was also proposed that lower levels of stress and vacancy concentration in the longer reservoir could partially contribute to the better electromigration reliability of interconnect with the longer reservoir.
The Design of Multilayered Polysilicon for MOEMS Applications
Authors: Sherman D. , Kahn H. , Phillips S.M. , Ballarini R. , Heuer A.H. 
Published: April 2011

ABSTRACTA rigorous analysis of a multilayered polysilicon laminated system, constructed by alternating deposition of low-pressure chemical vapor deposition (LPCVD) polysilicon at two different temperatures is presented. Different residual deformation fields are generated in these polysilicon thin films as a function of fabrication temperatures, due to different crystallization behavior at the two temperatures. The combination of the two layers, however, enables precise control of the radius of curvature of released structures, provided the material properties are well defined. We describe a new method, which combines experimental and numerical procedures, to define the material properties, which are responsible for the residual stresses as a function of layer thickness, as well as a procedure to design the desired curvature of a multilayered Micro-optical-electromechanical system (MOEMS) device. A linear deformation field is assumed. It is shown that precise design of the thicknesses of the individual layer is a prerequisite for controlled curvature. The procedure we have developed predicts the curvature of multilayered polysilicon systems with good precision.
Wear and Adhesion Optimization of Thin TiAlN Films by Structure Design
Authors: E. Lugscheider , Knotek O. , Bobzin K. , Beckers M. , Colmenares C. , Leyendecker A. , Erkens G. 
Published: April 2011

ABSTRACTThe structure of TiAlN and other thin films depends on the coating method, parameter variation and an eventual treatment of the coating after deposition. Concerning the coating process, reactive sputter and evaporation parameters influence structure formation as well as plasma driven chemical reaction on the substrate surface. Besides, crystal formation and agglomeration depends on energetic level and flow rates in the coating system, the kind and number of reactive partners, temperature and specific parameters of the coating plant.Post-deposition treatments on the other hand may influence the formation of residual stresses but not the crystallization of different phases within the complete coating. Besides, mechanical treatment may change the coating's morphology which may be important depending on the application since sometimes a columnar structure is to be optimized in size, amount and location. Thus a homogeneous coating is not always the optimum solution. In the experiments presented here we investigated the wear properties of thin TiAlN films. They were post-treated by sandblasting and heating in order to reduce frictional forces between the contacting bodies or analyze the effects of elevated temperatures respectively. These wear properties were evaluated by turning of 42CrMo4V at low cutting speed.
Coarse-Grained Molecular Dynamics: Dissipation Due to Internal Modes
Authors: Rudd Robert E. 
Published: April 2011

ABSTRACTWe describe progress on the issue of pathological elastic wave reflection in atomistic and multiscale simulation. First we briefly r eview Coarse-Grained Molecular Dynamics (CGMD). Originally CGMD was formulated as a Hamiltonian system in which energy is conserved. This formulation is useful for many applications, but recently CGMD has been extended to include generalized Langevin forces. Here we describe how Langevin dynamics arise naturally in CGMD, and we examine the implication for elastic wave scattering.
Self-assembling and Ordering of Ge/Si Quantum Dots on Flat and Nanostructured Surfaces
Authors: Motta N. , Sgarlata A. , Balzarotti A. , Rosei F. 
Published: April 2011

AbstractWe have studied by Scanning Tunneling Microscopy (STM) the effect of step bunching on Ge/Si(111) epitaxy. We have verified that self-organization of Ge islands is greatly influenced by “step bunching” which arises from the flash-annealing procedure used to reconstruct the Si surface. Two different growth regimes arise: initially islands nucleate and evolve only at steps, up to complete ripening; subsequently the same evolution is observed on flat areas of the sample. The average distance between islands and steps is nearly constant, originating a single row of equally spaced islands, followed by other rows of islands in between. The exploitation of this phenomenon, which is governed by the surface diffusion length of Ge on Si (estimated from our data) and by the terrace width, constitutes one possible path to achieve self-organization of quantum dots.
Optical and structural prorerties of InAs epilayer on graded InGaAs
Authors: Kim Gu Hyun , Choi Jung Bum , Lee Joo In , Kang Se-Kyung , Ban Seung Il , Kim Jin Soo , Kim Jong Su , Lee Sang Heon , Leem Jae-Young 
Published: April 2011

AbstractWe have studied infrared photoluminescence (PL) and x-ray diffraction (XRD) of 400 nm and 1500 nm thick InAs epilayers on GaAs, and 4 nm thick InAs on graded InGaAs layer with total thickness of 300 nm grown by molecular beam epitaxy. The PL peak positions of 400 nm, 1500 nm and 4 nm InAs epilayer measured at 10 K are blue-shifted from that of InAs bulk by 6.5, 4.5, and 6 meV, respectively, which can be largely explained by the residual strain in the epilayer. The residual strain caused by the lattice mismatch between InAs and GaAs or graded InGaAs/GaAs was observed from XRD measurements. While the PL peak position of 400 nm thick InAs layer is linearly shifted toward higher energy with increase in excitation intensity ranging from 10 to 140 mW, those of 4 nm InAs epilayer on InGaAs and 1500 nm InAs layer on GaAs is gradually blue-shifted and then, saturated above a power of 75 mW. These results suggest that adopting a graded InGaAs layer between InAs and GaAs can efficiently reduce the strain due to lattice mismatch in the structure of InAs/GaAs.
In-situ surface x-ray scattering study on the buried interfacial layer of Co/Si(111) interface
Authors: Kang Tae Soo , Je Jung Ho , Kim Hyo Jung , Noh Do Young , Kim Nam Dong , Chung Jin Wook 
Published: April 2011

AbstractThe highly strained interfacial structure and reaction of Co on Si(111) in the initial growth stage was studied by in-situ surface x-ray scattering. Co was deposited on Si(111) – (7×7) reconstruction by electron beam evaporation in ultra high vacuum. Our study reveals that the interfacial layer, formed by the reaction of Co with Si in the initial growth stage at room temperature, is a silicide layer with stoichiometry of Co2Si. The interfacial silicide layer is a commensurate phase of pseudohexagonal Co2Si, which shows a significant local atomic displacements imposed by Si substrate. The intensity oscillations at the anti-Bragg position with Co coverage show that a layer-by-layer consumption of silicon substrate occurs for the first 15 monolayers (ML) of Co deposited.
SiGe Epilayer Stress Relaxation: Quantitative Relationships Between Evolution of Surface Morphology and Misfit Dislocation Arrays
Authors: Gray Jennifer L. , Hull Robert , Floro Jerrold A. 
Published: April 2011

AbstractStress relaxation mechanisms have been investigated during growth of SiGe/Si heterostructures in a regime where misfit dislocations and surface morphological evolution strongly interact. Stress evolution was measured in real time using in situ wafer curvature measurements during molecular beam epitaxy of Ge0.3Si0.7 on Si (001). This real-time data has been combined with detailed analysis of the evolving surface morphology and misfit dislocation density using atomic force microscopy and transmission electron microscopy. Several distinct stages of microstructural evolution were observed during epitaxial growth of Ge0.3Si0.7alloys at intermediate temperatures (550°C) and relatively high deposition rate (0.9 Å/s). Initial planar, coherent growth was followed by pyramidal pit formation in the metastable wetting layer for 15nm thick films. Subsequent cooperative nucleation of island ridges occurs along <100> directions surrounding the pits. Dislocations are next introduced into the film abruptly at 50nm film thickness and relieve 40% of the film stress by 100nm of growth. Cross-hatch features aligned along the <110> directions accompany the introduction of misfit dislocations. As the dislocation density increases in the film, the coherent island/pit structures begin to disappear and the film morphology is dominated by the evolving cross-hatch. Implications for competitive and/or correlated relaxation of strain by misfit dislocations and surface morphology based upon this data will be discussed. This work demonstrates that combining real-time stress measurements with microscopy enables mechanistic and quantitative understanding of coupled relaxation modes in strained layer heteroepitaxy.
Computational Investigation of Selective Movpe of AlXGa1-XAs in Presence of Hcl
Authors: Nemirovskaya Maria , Cavallotti Carlo , Jensen Klavs 
Published: April 2011

AbstractThe deposition of AlGaAs in the presence of HCl was investigated at the macroscopic and mesoscopic scales. Fluid dynamics simulations were first performed in order to study the dependence of the deposition rate on the operating conditions. Unknown gas phase and surface kinetic parameters were estimated by quantum chemistry and transition state computations. The fluxes of all species to the surface were thus computed and provided the input to a kinetic Monte Carlo model used to investigate the morphology evolution of the film.
Rapid Prototyping of Ceramic Based Photonic Bandgap Structures
Authors: Synowczynski Jennifer , Hirsch Samuel , Gersten Bonnie 
Published: April 2011

ABSTRACTA three-dimensional photonic bandgap (PBG) structure was fabricated from CAD models using a method based on lost wax rapid prototyping and ceramic gelcasting. The inverse PBG mold was constructed from a low melting point thermoplastic using a high precision Sanders Rapid Toolmaker. An aqueous stable slurry (200-300 cp) containing 50-75wt% of the ceramic powders (BaSrTiO3, MgO), a 15wt% solution of monomer (Methacylamide) and crosslinker (Poly(ethylene glycol) dimethacrylate), and a free radical initiator (2,2'Azobis(2-amidino-propane) dihydrochloride) was cast into the mold. A polymerization reaction was thermally activated at 50°C to immobilize the ceramic powders. The wax mold was then removed by drying the green body in a high humidity oven at 120°C. Scanning Electron Microscopy (SEM) of the unfired part showed that atmosphere hampered the polymerization reaction at the surface of the part. The green density, sintered density, and permittivity all increased as the solids loading increased. In order to optimize the dielectric properties and minimize cracking and warping in the sintered part, the solids loading had to be greater than 80 wt%. This study investigated several steps in the lost mold / gelcasting procedure including stabilizing the ceramic suspension, the correlation between the solids loading and the green and sintered densities, binder removal, and the effect of shrinkage during sintering on the net shape.
Dielectric Properties of Spray Deposited BaTiO3 and Ba0.68Sr0.32TiO3
Authors: Ahn Kipyung , Wessels Bruce W. , Greenlaw Robert , Sampath Sanjay 
Published: April 2011

ABSTRACTThe microstructure and dielectric properties of BaTiO3 and Ba0.68Sr0.32TiO3 thick films deposited by thermal spray were investigated. The as-deposited films were predominantly crystalline with a small amount of an amorphous second phase. The as-deposited BaTiO3 films had dielectric constants as high as 240 at room temperature. Upon annealing in air at 500°C, the dielectric constant increased to 480. This increase in dielectric constant was attributed, in part, to the crystallization of the amorphous second phase. The stabilized phase depended on the spray process used. The high velocity oxy fuel (HVOF) spray process resulted in the deposition of paraelectric BaTiO3, whereas the plasma spray process resulted in the ferroelectric phase.
Direct-Write Construction of Tissue-Engineered Scaffolds
Authors: Kachurin Anatoly M. , Stewart Robert L. , Church Kenneth H. , Warren William L. , Fisher John P. , Mikos Antonios G. , Kraeft Stine-Katherine , Chen Lan Bo 
Published: April 2011

ABSTRACTA computer-controlled xyz dispensing system called the Biological Architecture Tool (BAT) has been extensively tested in the creation of multilayered and three-dimensional biological objects: tissue scaffolds and plain and patterned cellular-array slides. The BAT dispensing system has proven its versatility and reliability in tissue engineering and biological experiments. The potential employments of modified versions of the xyz dispensers for in vivo minimally invasive surgery and other in vitro aspects of biological and medical research are discussed.
Sensitivity and Resolution Limits in Scanning Capacitance Microscopy
Authors: Lányi 'Stefan , Hruŝkovic Miloslav 
Published: April 2011

AbstractThe capacitance detection techniques, applicable to Scanning Capacitance Microscopes, have been analyzed from the point of view of signal-to-noise ratio that finally affects the achievable lateral resolution. It was found that comparable sensitivities can be achieved from relatively low frequencies below 1 MHz up to the GHz region. On conducting surfaces, resolution better than 5 nm has been achieved. It is limited by the minimum probe-to-sample distance, below which large tunneling current would occur. Increasing the applied voltage above a few volts increases the sensitivity at the cost of lateral resolution, since, at high voltage and small probe-sample distance, field emission could occur.
Detection of Compositional Fluctuations in High Temperature Exposed Waspaloy
Authors: Zou Xiaodong , Makram Tariq , Gerhardt Rosario A. 
Published: April 2011

AbstractWaspaloy is a nickel base super-alloy used in aircraft engines. When this alloy is placed in service, it is subjected to long term exposure at high temperatures, which can cause the reinforcing gamma prime precipitate population to fluctuate and thus affect its structural integrity. The population fluctuates as a result of coarsening, dissolution or re-precipitation. Samples exposed to 1200° F for times ranging from 0 to 12626 hours were characterized using impedance spectroscopy, microhardness measurements, x-ray diffraction and quantitative stereology. Two important parameters were derived from the impedance measurements: (1) the imaginary admittance peak magnitude (Ymax) and (2) the associated relaxation frequency (fmax). As the distribution, shape and size of the precipitates change with exposure time, these parameters were also found to vary. In addition to the changes in precipitate geometry, lattice constant changes detected by analyzing x-ray diffraction data suggest that there are compositional shifts in the matrix as well as the gamma prime precipitates. Furthermore, the preferred orientation of the precipitates can also be seen to change with exposure time. These changes in composition, size and shape as a function of thermal exposure time are accompanied by changes in the volume fractions of primary and secondary gamma prime particles present. Using effective medium models, it is possible to predict that the measured properties are related to the gamma prime population. The grain boundary carbides do not appear to play any role at the conditions presented.