bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Treatment Effect on Properties of Ni-P-Al2O3 Composite Coatings
Authors: León-Patiño Carlos A. , García-Guerra Josefina , Aguilar-Reyes Ena A. , Lemus-Ruiz José
Published: April 2011

Ni-P and Ni-P-Al2O3 composite coatings are obtained by electroless plating on steel substrates. Alumina particles with an average particle size of 5 microns are added to the bath in loads of 5, 10, 15 and 20g/L. It is found a maximum retention of 18.2 vol.% Al2O3 for a ceramic load of 10g/L. The composition of the binary Ni-P deposits is 9.3 wt.% P and the balance nickel. The addition of ceramics to the electroless solution induces a reduction of phosphorous content to 9.0, 8.3, 7.9 and 7.3%, respectively. The deposited coatings are heat-treated in the temperature range between 100 and 500°C and holding times from 30 to 300 minutes. A maximum hardness of 1600 HV0.1 is obtained for composite coatings containing 18.2 vol.% Al2O3 treated at 400 °C/1h. The uniform distribution of ceramics and precipitation of fine Ni3P and Ni12P5 precipitates are responsible of the hardening of the nickel matrix.
In-Situ Dynamic High-Resolution Transmission Electron Microscopy Investigation of Guest-Layer Behavior During Deintercalation of Mercury Titanium Disulfide
Authors: Mckelvy M. , Sidorov M. , Marie A. , Sharma R. , Glaunsinger W.S.
Published: April 2011

Deintercalation processes for the model neutral intercalation system HgxTiS2 (1.25≥x>0.00) have been investigated using dynamic high-resolution transmission electron microscopy. X-ray powder diffraction and thermogravimetric analysis demonstrated the intercalation process is thermally reversible, both structurally and compositionally. In situ deintercalation of stage- 1 compounds was induced by thermal/electron-beam heating during DHRTEM observation. The resulting deintercalation processes were followed with 0.03 second time resolution. The deintercalation processes observed possess a strong similarity to nucleation and growth processes. Deintercalation was observed to “nucleate” by the initial deintercalation of an external-most or internal guest layer, with further deintercalation of the guest “growing” away from the onset layers. This results in generally randogmuelsyt lsatyaegresd greengeiroanllsy, occasionally containing regions of short-range order, that expand away from the deintercalation onset layers.
Moire Patterns in High Resolution Electron Microscopy Images
Authors: Reyes—Gasga J. , Tehuacanero S. , Zorrilla C.
Published: April 2011

Moiré patterns are so often observed in the HREM images and they could be mistaken as the direct image of the atomic structure of the sample under analysis. In this workwe presented some examples of these patterns and their computer graphic simulations.
Interfacial Roughness in GaAs/A1GaAs Multilayers: Influence of Controlled Impurity Addition
Authors: Nayak S. , Redwing J.M. , Kuech T.F. , Savage D.E. , Lagally M.G.
Published: April 2011

Impurities at heterointerfaces can alter the interfacial structure resulting in changes in physical, electrical and optical properties. We present a study of the interfacial roughness of GaAs/A1xGa1-xAs superlattices which were grown using controlled addition of oxygen at the interface. The interfacial properties were characterized by x-ray diffraction. The morphology of the surface was determined by Atomic Force Microscopy (AFM). X-ray diffraction measurements, both θ-2θ and rocking curves, were used to analyze the correlated and uncorrelated component of the interfacial roughness. A strong difference in the interfacial roughness was observed depending on whether the intentional oxygen incorporation occurred at the GaAs-to-A1GaAs interface or at both interfaces. When oxygen is incorporated at both interfaces, the x- ray reflectivity of the superlattice is decreased considerably resulting from a much higher interfacial roughness. The substrate miscut has a significant effect on RMS roughness, correlated roughness and its correlation length when oxygen is incorporated at the GaAs-to-A1xGa1-xAs interface.
Polarization, Interference Contrast, and Photoluminescence Imaging in Near Field Optical Microscopy
Authors: Vaez-Iravani M. , Toledo-Crow R. , Rogers J.K.
Published: April 2011

The design and operation of a number of techniques in near field optical microscopy are described. Specific attention is paid to the three modalities of polarization, interference contrast, and photoluminescence imaging. By premodulating the polarization state of the sample beam, pure, linear, polarizing microscopy is performed. In addition, polarization anomalies are observed in the focal plane of a high numerical aperture lens. Amplitude and phase contrast imaging is performed in a feedback stabilized Mach-Zehnder interferometer. Magneto-optically induced polarization shifts are detected interferometrically, resulting in linear sensitivity. Localized photoluminescence is induced in porous silicon, and the results are correlated with the topography of the sample.
Photon Tunneling Microscopy Applications
Authors: Guerra John M.
Published: April 2011

With photon tunneling microscopy (PTM), dielectric, semiconductor, and other surfaces are imaged by means of the phenomenon of photon tunneling (or evanescent waves). Vertical resolution is detector limited to one nanometer and the vertical range is λ/2. Lateral resolution is better than λ/4 with a field-of-view up to approximately 125 µm. PTM produces images of samples independent of size and thickness in real-time without metallization, shadowing, vacuum, electrons, or scanning probes. Tunneling images are analog processed for realtime 3-D topographic imaging with continuous viewpoint and magnification control. In this paper PTM images of a variety of samples are presented and briefly discussed.
Electronic Structure of Layered and Linear Chain Materials by Scanning Probe Microscopy
Authors: Coleman R.V. , Dai Z. , Gong Y. , Slough C.G. , Xue Q.
Published: April 2011

Transition metal impurities such as Fe, Ni, and Co can be intercalated into the van der Waals gap of layer structure dichalcogenides and these modify the charge-density wave (CDW) structure and CDW energy gaps. Ordered superlattices associated with antiferromagnetic phases can be detected by both scanning tunneling microscopy (STM) and atomic force microscopy (AFM). STM spectroscopy indicates the formation of a mixed spin-density-wave (SDW) and CDW (SDWCDW) in the doped materials. The quasi-one dimensional trichalcogenide NbSe3 exhibits two CDW transitions and the presence of dilute transition metal impurities produces ordered superlattices due to long range screening of the impurities.
Tensile Deformation-Induced Microstructures in Freestanding Copper Thin Films
Authors: Keller R. R. , Phelps J. M. , Read D. T.
Published: April 2011

Existing work in the mechanical behavior of thin films focuses mainly on measurement of macroscopic properties without strong correlation to microstructural features. We used transmission electron microscopy (TEM) to characterize the microstructures of free-standing copper thin films both before and after monotonic tensile deformation in an ex-situ thin film tensile testing system, as well as during in-situ loading in the TEM. The defect structures contributing to plastic deformation were investigated with an emphasis on comparison to mechanisms known to operate in bulk copper. The thin film exhibited much lower ductility (approximately 1%) than that normally observed in bulk form (greater than 40%). The predominant plastic deformation mechanisms did not include the typical dislocation activity that occurs in bulk copper, but rather greatly inhibited dislocation interactions typical of stages I and II hardening only. The absence of those structures normally found in tensile-deformed bulk copper is attributed to the differences in characteristic sizes of features within the microstructure available for deformation in bulk versus evaporated thin film material, that is, grain size and film thickness. The thin film ductility is an order of magnitude lower than what has been observed in bulk, ultrafine-grained copper, implying that a pure thin film effect on ductility exists and is significant. Microstructural features both near to and far from the fracture surface regions will be presented.
Effects of Thin Film Stress in Sub Micron Multilevel Devices
Authors: Prasad Sharad , Lu Y.C. , Li D.K , Reddy G.S. , Chen F.
Published: April 2011

Submicron high density devices require multilevel interconnections. In multilevel interconnections, issues relating to planarity, stress voiding of metals and stress cracking of the dielectric(s) play an dominant role.As the levels of interconnect go up so does the stress level. A high stress level in the intermediate dielectric can cause cracks which ultimately lead to device failure. In this paper we present a novel method to detect stress cracking using focussed ion beam. This method is correlated with wet chemical etch process and RIE.The phenomenum of cracking of dielectric(s) is studied and different technology aspects are considered. Using the focussed ion beam a robust dielectric is developed.
Epitaxy of Erbium Doped LiNbO3 Films Produced by Pulsed Laser Deposition
Authors: Bauer S. , Beckers L. , Fleuster M. , Schubert J. , Zander W. , Buchal Ch.
Published: April 2011

The growth of thin films of LiNbO3 and Er:LiNbO3 on LiNbO3 single crystals produced by pulsed laser deposition (PLD) was studied. Samples were characterized by RBS/Channeling Spectrometry, X-ray diffraction measurements, Secondary Ion Mass Spectroscopy (SIMS) and photoluminescence (PL) measurements. Film preparation is performed in a two-step process including deposition and in-situ-annealing. Buried Er doped layers of approx. 800 nm thickness were grown.
C− Outgrowths in C+ Thin Films of LiNbO3 on Al2O3-c
Authors: Kingston J. J. , Fork D. K. , Leplingard F. , Ponce F. A.
Published: April 2011

Thin-film waveguides of LiNbO3 have been grown on Al2O3-c by off-axis rf magnetron sputtering. The films have been characterized optically by prism coupling measurements, crystallographically by x-ray diffraction, and morphologically by atomic force microscopy. We find that optical losses can be dominated by scattering from large outgrowths that litter the surface of the film. These outgrowths are c− grains imbedded in a c+ matrix. Although some grains nucleate c−, others have their polarity reversed from c+ to c− after nucleation. A model will be presented to explain the preferential nucleation of c+ grains on Al2O3-c. The c− grains grow much faster than the c+ ones because of attractive coulombic forces between the c− grains and the ionized Li and Nb species in the sputter plume.
BaTiO3 Thin Films Prepared By Dip-Coating Process
Authors: Della Nelcy , Mohallem Santina
Published: April 2011

Thin films of pure barium titanate have been prepared by the sol-gel process from organomettalic sols containing titanium alkoxides and barium acetate (molar ratio [Ba]/[Ti]=l). It leads to transparent, homogeneous and adherent coatings. The influence of various parameters such as chemical concentration, viscosity, withdrawal speed and temperature of densification on film thickness is described. The films were characterized by X-ray diffraction during their heat treatment. Their crystallization temperature was observed to be around 450°C. No variations in the optical properties were observed during the crystallization, and it occurred without the appearance of cracks or pinholes. Tetragonal BaTiO3 structure was observed, and the ferroeletric properties were investigated as functions of thickness and grain size.
Homogeneity of Wet Oxidation by RTP
Authors: Glück M. , König U. , Hersener J. , Nenyei Z. , Tillmann A.
Published: April 2011

The implementation of a wet oxidation process in an RTP system using a bubbler with deionized water is described. A special process related calibration in a wet atmosphere, by means of pyrometer and thermocouple readings, allows one to improve the temperature accuracy during the oxidation to an offset of only + 1 to 2°C. High oxide growth rates, up to a factor of 1.8 above literature data have been achieved. Wet and dry RTO oxides are compared and related to the expectations from growth models. Effects of growth time (10 s to 4 min), growth temperature (675°C-950°C), substrate orientation (100,111), preparation (e.g. HF) and bubbler temperature (20°C-90°C) are presented. The uniformity of oxides on 4 and 6 inch diameter wafers are discussed. Preferentially by the use of a silicon guard ring and by adjusting lamp power and gas flow rates excellent results concerning uniformity (standard deviations 2σ: 1-2 %) and reproducibility (variation of 0.5 to 0.75 % at least over 12 wafers) are obtained.
Gas Flow Engineering in Rapid Thermal Processing
Authors: Nényei Z. , Sommer H. , Gelpey J. , Bauer A.
Published: April 2011

Gas flow engineering involves gas dynamics optimization for effective ambient change before heating and for homogeneous convective cooling of the wafers during the heating steps. Multiple gas buffle system, dynamical gas handling, low pressure operation, low temperature edge guard ring and independent top and bottom heater bank control are the proper tools for this optimization. Silicon surface or interface damage during inert gas anneal can be avoided by addition of a small amount of oxygen.
Influence of H2 on Ge Surface Segregation in Si/SiGe Heterostructures Grown by RTP/VLP-CVD
Authors: Rong Zhang , Hongbin Huang , Shulin Gu , Kai Yang , Yi Shi , Ronghua Wang , Youdou Zheng , Duan Feng
Published: April 2011

In this paper we report the influence of H2 on Ge surface segregation in Si/SiGe heterostructures. The sample were grown on Si(001) substrate tinder different gas flow of H2 by RTP/VLP-CVD. Auger electron energy spectroscopy(AES) has been used to determine the Ge distribution in Si/SiGe heterostructures. The results indicate that H2 can strongly alter the mechanism of Ge surface segregation and change the distribution of Ge atoms.
Giant Magnetoresistance and Structural Study of Permalloy/Silver Multilayers During Rapid Thermal Annealing
Authors: Roozeboom F. , Gideonse I. , Duchateau J.P.W.B. , Neerinck D.G. , Munsters H.T.
Published: April 2011

The Giant Magnetoresistance effect with high field-sensitivity was recently discovered in multilayers of alternating ferromagnetic and non-ferromagnetic layers. Some of these layer structures may find industrial application in miniaturized sensor and high-density digital magnetic recording technologies which require materials with large changes in electrical resistance at low magnetic fields.

In this paper we report on Rapid Thermal Annealing experiments done on a series of multilayers of alternating thin permalloy (Ni80Fe20) and silver films. The layers were sputter deposited on thermally oxidized Si (100) substrates. Samples were annealed in nitrogen at temperatures ranging from 280 to 340 °C for 30 seconds to 10 minutes, yielding magnetoresistance data as high as 5% and a maximum field sensitivity of 4.6% per kA.m-1. X-Ray diffraction analysis, showing the gradual formation of an Ag (111) shoulder peak at 20 = 38.3° upon annealing, supports a recently published hypothesis that the appearance of the GMR effect is annealinduced by a change of the microstructure due to diffusion, causing notching and disruption of the permalloy layers in the superlattice.
An Environmentally Clean Liquid Precursor of Sulfur for Metalorganic Chemical Vapor Deposition (MOCVD) of Transition Metal Di-Sulfide Thin Films.
Authors: Gadgil Prasad N.
Published: April 2011

A three member ring compound propylene sulfide, C3H6S is employed as a sulfur source for the Metalorganic Chemical Vapor Deposition (MOCVD) of stoichiometric thin films of iron pyrite (FeS2). Iron pentacarbonyl Fe(CO)5, a liquid, was precursor for iron. Propylene sulfide, (PS) a liquid ( b. p. = 72–75 °C, v. p. ∼ 87 torr @ 20°C ) decomposes cleanly and quantitatively as S2 and C3H6 (propylene) above 250°C. Deposition of thin films of pyrite and their analysis by X-ray diffraction and Mossbauer and X-ray Photoelectron spectroscopy is described. Liquid state, long term stability, clean and low temperature generation of active S2 species in vapor phase and gaseous by product C3H6 which can be burned to CO2 and H2O are the key advantages offered by propylene sulfide as a sulfur source.
Multiphase Electrodispersion Precipitation of Zirconia
Powders
Authors: Harris Michael T. , Sisson Warren G. , Scott Timothy C. , Basaran Osman A. , Byers Charles H. , Ren W. , Meek Thomas T.
Published: April 2011

The multiphase electrodispersion precipitation of zirconia powders has been
done in the electric dispersion reactor (EDR). This paper presents the first
results obtained where the bench-scale EDR unit was operated in the
continuous mode to synthesize 130 ± 2 g of ZrO2 powder in
approximately 12 h. An aqueous solution of zirconyl nitrate was dispersed
and precipitated in a 2-ethyl-l-hexanol continuous phase containing 0.012
M to 0.12 M ammonia. A
gravity settler was used to remove soft agglomerates of the ZrO2
particles from the organic solvent. Electric bed filtration was employed to
remove the fines from the solvent, which was then recycled.

The particle-size distribution was varied by changing the electric field
strength. At high field strengths (approximately 20 kV/cm), the particle
sizes ranged from approximately 0.1 to 5 μm. The dried powder had a
consistency of talcum powder. Microwave and conventional heating experiments
showed that the powders were sinterable. The BET surface area of the powders
ranged from approximately 20 to 90 m2/g.
Processing Effects on the Microstructure of Sol-Gel Derived SBN
Thin Films
Authors: Momoda L.A. , Gust M.C. , Mecartney M.L.
Published: April 2011

Microstructural changes in sol-gel derived
SrxBa1-xNb2O6 (SBN) thin
films were monitored as a function of chemical variations in the precursor
sol and of processing variations of the thin films. 6000À
Sr0.5Ba0.5Nb2O6 thin films
were deposited from different alkoxide based precursors under various
hydrolysis conditions. The tetragonal tungsten bronze structure was achieved
in films at temperatures on the order of 700°C. Preferential (001)
orientation of the tetragonal lattice was found to be very dependent upon
the substrate orientation as well as thermal treatment schedule.
Transmission electron microscopy (TEM) was used to examine the film
microstructure. Orientational effects were verified by TEM as well as a
tendency for a porous structure in the alkoxide derived films. Substrate and
processing dependent grain size and size distributions were also noted.
Grain-Size Effects on Diffuse Phase Transitions of
Batio3 Ceramics Obtained by Alkoxide
Precursors
Authors: Lobo R. P. S. M. , Moreira R. L. , Mohallem N. D. S.
Published: April 2011

Barium titanate ceramics have been obtained by sol-gel methods. The
dielectric investigations of these materials revealed the existence of
diffuse ferroelectric transitions. By using a phenomenological model, we
could demonstrate the existence of a simple relationship between the diffuse
character of the transition and the sample grain-size. This effect has been
attributed to interactions between charged defects on the grain surfaces and
the spontaneous polarization of the material.
Novel Phases in the V-P-O Catalytic System from Oxovanadium
Hydrogenphosphate Precursors
Authors: Amoros P. , Marcos M. D. , Alamo J. , Beltran A. , Beltran P.
Published: April 2011

Several biphasic VOP04/(VO)2P2O7
redox partners seem to be active in the catalytic cycles involved in the
mild oxidation of simple hydrocarbons to maleic anhydride. The present X-ray
time resolved thermal-diffractometric study reveals the existence of a new
anhydrous variety of the oxidized form, ω-VOPO4, which may appear
as an intermediate in the formation of the well known β-VOPO4.
This new phase only remains well crystallized at relatively high
temperatures, and when it is allowed to cool down in wet air
VOPO4·2H2O results. In turn, another well defined
phase, VOPO4·1.58H2O, can be recognized in the course
of the hydration process.
Spinnability of Silica Sols: the Role of Alkoxy Group
Exchange
Authors: Prabakar S. , Assink R.A. , Irwin A.D.
Published: April 2011

The exchange and spinnability of several systems with the general form
Si(OR)4 (where R = CH3, C2H5)
in ethanol, propanol and butanol were investigated. We have followed the
alkoxy group exchange, the hydrolysis and condensation reactions and the Q
distributions of these systems using 29Si and 17O NMR.
The observed differences in spinnability of the various sol-gel systems are
attributed to the effect of the bulkiness of the alkoxy group on its
reactivity.
Nano-Crystalline Powders and Suspensions Generated Using A
Flow-Through Hydrothermal Process, Part I: Characterization
Authors: Darab John G. , Buehler M. F. , Linehan J. C. , Matson D. W.
Published: April 2011

A wide range of ultra-fine, nano-crystalline powders and suspensions have
been produced using the Rapid Thermal Decomposition of precursors in
Solution (RTDS) technology. These materials include single and
multi-component iron-, zirconium-, titanium-, nickel-, and
chromium-oxide/oxyhydroxide powders. RTDS, which was developed at Pacific
Northwest Laboratory, is a flow-through hydrothermal process capable of
producing nano-crystalline particulate material at rates of up to 100 grams
of solid per hour. We present the results of characterization efforts on
RTDS iron oxyhydroxide and zirconium oxide systems. As-collected RTDS
suspensions were characterized using optical light scattering. Separated
RTDS powders were evaluated using X-ray diffraction, electron microscopy,
gas adsorption analysis, thermal gravimetric analysis, and chemical
analysis.
Recent Developments in Organically Doped Sol-Gel Sensors: A
Microns-Scale Probe; Successful Trapping of Purified Polyclonal Antibodies;
Solutions to the Dopant-Leaching Problem
Authors: Aharonson N. , Altstein M. , Avidan G. , Avnir D. , Bronshtein A. , Lewis A. , Liberman K. , Ottolenghi M. , Polevaya Y. , Rottman C. , Samuel J. , Shalom S. , Strinkovski A. , Turniansky A.
Published: April 2011

We describe recent advances made in our laboratories in the general field of
organically and bio-organically doped sol-gel sensors. The developments
described are: (a) The first miniaturization of a sol-gel sensor down to the
microns scale, with potential applications to near-field optical microscopy,
using a fluorescent pH-indicator. (b) The first successful sol-gel
encapsulation of purified polyclonal antibodies, and in particular an
anti-nitroaromatics immunoglobulin, with which selective sensing of
nitroaromatics, an important class of environmental pollutants, was
demonstrated, (c) The leaching problem, occasionally encountered in doping
procedures, is solved by two methodologies: First, TMOS polymerization at
high acidity and low water content was found to result in non-leachable yet
reactive matrices, as demonstrated with O2 sensing by excited
state pyrene and with H+ sensing by excited state pyranine; and
second, doping with molecules capable of forming a covalent bond within the
encapsulating cage results in the permanent anchoring of the dopant. Thus,
Methyl-Red, a pH indicator, was derivatized with a silylating residue, and a
polymerizing TMOS was doped with it forming a pH-shifted indicator. With
both methodologies, leachability was practically zero.
Photochemical Formation of V4+ in a Layered Vanadium
Pentoxide Hydrate
Authors: Kittaka S. , Sumida M. , Kuroda Y.
Published: April 2011

Formation of V4+ upon UV-irradiation in the
V2O5 · n H2O was
confirmed and the layered structure of this material was discussed on the
basis of an ESR analysis of the species produced therefrom in combination
with spectral change upon H2O adsorption.
Epitaxy in the Crystallization of Feldspar Gels and
Glasses
Authors: Liu Chunling , Komarneni Sridhar , Roy Rustum
Published: April 2011

The crystallization behaviors of stoichiometric feldspar gels and glasses
before and after seeding have been compared, and the role of epitaxy in
their crystallization upon seeding has been studied. The crystallization
products were mainly determined by X-ray diffraction (XRD) analysis and
epitaxy upon seeding was examined with a scanning electron microscope (SEM),
and energy dispersive spectrometry (EDS). It was found that upon
isostructural seeding, Na-and K-feldspars crystallized epitaxially from
their gels and/or glasses. Little or no seeding effect was found in
CaAl2Si2O8 and
SrAl2Si2O8 gels and glasses.
Isostructural seeding in BaAl2Si2O8 gels
increased the formation of Ba-feldspar (monoclinic celsian) epitaxially,
whereas without seeding hexacelsian was the crystallization product.
Fluorescence Line Narrowing Studies of Eu3+-Doped
Silica Gel-Glasses
Authors: Lochhead M. J. , Bray K. L.
Published: April 2011

Broadband fluorescence and fluorescence line narrowing (FLN) spectra are
presented for Eu3+ ions in
Eu2O3-SiO3 and
Eu2O3-Al2O3-SiO3
systems prepared by the sol-gel process. Clustering of rare earth ions in
silica glass can be a limiting factor in the design and engineering of
optical device materials. The addition of Al2O3 is
known to help disperse rare earth ions in sol-gel silica. In order to
develop a more detailed understanding of how Eu3+ is incorporated
in these materials, time-resolved, laser-induced FLN studies at 77 K have
been performed using a pulsed dye laser to selectively excite subsets of
ions in the inhomogeneously broadened 7F0⇆
5D0 manifold. Fluorescence spectra are discussed in
terms of rare earth ion clustering, energy transfer, and bonding site
symmetry. It is concluded that Eu3+ ions cluster in sol-gel
silica and that the addition of alumina assists in dispersing
Eu3+ ions.
Process Dependence of Orientation of Ribbon-Like Aromatic Molecules in Glassy Carbon
Authors: Maleki H. , Ila D. , Holland L. R. , Zimmerman R. L. , Jenkins G. M.
Published: April 2011

Flat glassy polymeric carbon samples were prepared from phenolic resin by three techniques: spray coating, spin coating and molding. Cured at 110°C-180°C and pyrolyzed in argon at 600°C or at 1000°C, samples then were studied by RBS for trace impurities, by ESCA for surface oxidation and contamination and by Raman microprobe of the top surface and perpendicular to that for preferred orientation of aromatic ribbons. An increase of 13% to 24% in the relative area under the corresponding Raman peaks indicates increased orientation of the ribbon-like aromatic molecules in the sprayed and spin coated samples as compared with the molded sample.
Carbon Fibers Produced from Graphite Fluoride by Thermal Decomposition in an Inert Environment
Authors: Hung Ching-Cheh
Published: April 2011

Slow defluorination of graphite fluoride fibers during nitrogen heating produces both graphitized carbon fibers having high defect density and a yellow film which may contain fullerenerelated materials. The carbon fibers thus obtained can pick up some copper and form aluminum composite during direct molten metal exposure. Explosion of graphite fluoride fibers during quick nitrogen heating produced amorphous carbon containing very little fluorine. They cannot be wetted by copper, but pick up some aluminum during direct molten metal exposure. By either spreading the graphite fluoride fibers apart or adding a small amount of bromoform into the graphite fluoride fibers before the quick nitrogen heating, the possibility of explosion can be reduced.
Nickel Mediated Transformation of Amorphous Carbon to Graphite
Authors: Itoh Toshio , Sinclair Robert
Published: April 2011

Reactions between Ni and amorphous carbon (a-C) below 600°C have been investigated using differential scanning calorimetry (DSC) and in situ annealing in a transmission electron microscopy (TEM) of Ni/a-C layered films deposited by DC sputtering. DSC data show that there are two exothermic peaks in the temperature range around 200-600°C. One is a weak and broad peak below 500°C and the other is a strong and sharp peak at around 530°C. In situ heating in the TEM revealed that the low temperature peak corresponds to a series of reactions for nickel carbide (Ni3C) formation and decomposition into Ni and carbon, most likely in a glassy state. The higher temperature peak was found to correspond to graphitization of a-C by a solution-precipitation mechanism. Graphite formed in this process is strongly textured with the (0002) graphite basal planes parallel to the original Ni/a-C interface.
Deuteron Magnetic Resonance and Infrared Absorption Studies of Structure and Dynamics in Amorphous Hydrogenated Carbon and Carbon Nitride
Authors: Lin Shu-Han , Feldman Bernard J. , Bodart J. R. , Bork V. P. , Kernan M. J. , Fedders P. A. , Norberg R. E.
Published: April 2011

Deuteron magnetic resonance (DMR) and infrared absorption spectra have been measured in amorphous hydrogenated carbon (a-C:H and a-C:D,H) and amorphous hydrogenated carbon nitride (a-CN:D,H) films plasma-deposited onto room-temperature substrates from feedstock mixtures of CH4, N2, and D2. DMR spectra and transient magnetization recoveries were measured between room temperature and 4 K. Recoveries are dominated by magnetization transport under extreme inhomogeneity. Methyl rotors CDx H3-x freeze out below 77 K. From the infrared absorption spectra, NH2, CHx, double bonded C-C, and triple bonded C-N stretching modes are observed. As a function of increasing nitrogen concentrations, the NH2 and C-N intensities dramatically increase while the CHx and C-C intensities decrease. In films where the ratio of nitrogen to carbon plus nitrogen is greater than 25%, the absorption spectra are dominated by NH2 stretching and bending modes; in contrast, the DMR spectra show many CDxHy configurations and a broader NDxHy structure. Proton NMR shows significant hydrogen clustering in a-CN:D,H.
Distribution Function, Density and Hydrogen Content of Amorphous, Diamond-Like, Carbon Films Obtained by X-Ray and Neutron Scattering
Authors: Findeisen E. , Feidenhans'l R. , Vigild M. E. , Nielsen M. , Clausen K. N. , Foss M.
Published: April 2011

The structure of amorphous, diamond-like carbon films is described by the distribution function, obtained by X-ray scattering experiments. In particular the nearest neighbor distance and the average coordination number are determined. A combination of specular reflectivity of neutrons and X-rays enables us to measure not only the mass density, but also the concentration of hydrogen in the films, which varies in our case between 0 and 30 at. %.
Elastic Properties of Silicate Glass and Spin-On Glass Thin Films
Authors: Doucet L. , Carlotti G.
Published: April 2011

The elastic properties of dielectric films used in microelectronics, such as undoped, phosphorous doped and boron-phosphorous doped silicate glass, as well as spin-on glass, have been studied by means of the Brillouin light scattering technique. The phase velocity of both the surface Rayleigh wave and of the longitudinal wave in the film material have been measured and the two independent elastic constants c11 and c44 evaluated. This permitted us to derive the values of the Young’s modulus and of the Poisson’s ratio which are useful quantities for the modelling of the elastic properties of multilevel structures used in electronics. Moreover, the biaxial stress in the films has been measured by the substrate curvature method. This enabled us to study the evolution of the intrinsic stress with time, caused by water adsorption into the films. The evolution of the stress during thermal cycles has been also analyzed and the thermal expansion coefficient of the films estimated.
Composition Dependence of Hardness and Moduli in GeSi/Si-Heterostructures Measured by Nanoindentation
Authors: Roos B. S. , Richter H. , Morgenstern T. , Tillack B.
Published: April 2011

GexSi1-x layers (0 ≤ × ≤ 1), with thicknesses ranging from 0.1 to 1.2 µm, were grown on Si(100) and Si(lll) by chemical vapor deposition (APCVD, LP/RTCVD) and liquid phase epitaxy (LPE), respectively. A NanoTest 500 machine served for nanoindentation measurements to evaluate the hardness and elastic moduli. The GeSi layers show strong alloy hardening with an increase varying proportional to x(l-x) as reported for III-V and H-VI-semiconductors. Maximum hardness is close to x = 0.45 at one and a half of the silicon hardness. For binary alloys such as Ge-Si, which show complete solid solubility, the elastic moduli are generally assumed to vary linearly with composition. In contrast to that we found for the indentation modulus E/(l-v2) a positive deviation of 30 % from linear interpolation (Vegard’s law), proportional to x(l-x). The increase in the elastic constants is explained by the structural properties of the Ge-Si alloy.
Stress and its Effect on Intermixing in Si1-xGex/Si Superlattices
Authors: Prokes S. M.
Published: April 2011

Interdiffusion behavior in long-period Si1-xGex/Si as a function of growth conditions and external stress is examined using x-ray diffraction and Raman Spectroscopy. Both symmetrically and asymmetrically-strained superlattices have been examined, and an activation energy for interdiffusion of 3.9 eV and 4.6 eV have been obtained, respectively. In addition, an enhanced interdiffusion has also been measured in an externally stressed asymmetric superlattice. In both cases, enhanced interdiffusion has been measured whenever the Si barrier layers experience tensile stress during annealing. The Raman spectroscopy supports this result, showing an enhanced Ge diffusion into the Si barriers when these barriers are put under tensile stress. This result will be discussed in terms of the kinetics of defect formation and motion in the strained Si barriers.
Thermal Stresses in Passivated AlSiCu-Lines From Wafer Curvature Measurement
Authors: Burges U. , Helneder H. , Schneegans M. , Beckers D. , Hallerbach M. , Schroeder H. , Schilling W.
Published: April 2011

A wafer curvature technique was used to measure the mechanical stresses during thermal cycling and the isothermal stress relaxation in passivated Ti/TiN/AlSi(l%)Cu(0.5%)-lines (aspect ratio: 0.92) in the in-plane directions, parallel and perpendicular to the lines. The evaluation of the measured curvature data is explained in detail. The evaluation procedure was tested with the help of passivated SiO2-lines in which the stresses can be calculated because both, the SiO2-lines and the passivation, behave elastically. Comparision to elastic Finite-Element-Method calculations show excellent agreement. The main results are:

a)

During thermal cycling all stresses in the AlSiCu-lines vary linearly with temperature without significant hysteresis. The stress parallel to the lines is higher than perpendicular to the lines. X-ray stress data from the same sample confirm the wafer curvature data and show, additionally, that the stresses in the two directions perpendicular to the lines are equal.

b)

The isothermal stress relaxation depends strongly on the temperature with a maximum at 250°C. Void formation and growth probably control the observed relaxation.
Correlation of the Stress-Temperature History with Microstructure in A1-0.5Cu and A1-0.15Pd Thin Films
Authors: Knorr D. D. , Rodbell K.P.
Published: April 2011

Blanket films (1 μm thick) of both A1-0.5Cu and A1-0.15Pd were deposited at room temperature, 150°C, and 300°C. Stress in the as-deposited wafers increased with substrate temperature, as expected from the thermal expansion mismatch on cooling. All conditions were tiicrmally cycled to 450°C three times while continuously monitoring stress. The shapes of the curves were different for the two alloys because precipitates dissolve and reprecipitate in AlCu, but are present over the entire temperature range in AlPd. Lesser differences were evident comparing the stress-temperature behavior for the various substrate temperatures within a single alloy. The precipitate structure also influences the grain growth during thermal cycling, where substantially larger median grain sizes are found in AlCu compared to AlPd.
Influence of a Capping Layer on the Mechanical Properties of Copper Films
Authors: Keller R.-M. , Bader S. , Vinci R. P. , Arzt E.
Published: April 2011

The substrate curvature technique was employed to study the mechanical properties of 0.6 μm and 1.0 μm Cu films capped with a 50 nm thick Si3N4layer and to compare them with the mechanical properties of uncapped Cu films. The microstructures of these films were also investigated. Grain growth, diffusional creep and dislocation processes are impeded by the cap layer. This is evident in the form of high stresses at high temperatures on heating and at low temperatures on cooling. At intermediate temperatures on heating and cooling, stress plateaus a relatively low stresses exist. This can be explained by the so-called Bauschinger effect. A film thickness dependence of the stresses in the film could not be observed for capped Cu films.
Effect of CU and SI in Aluminum on Stress Change and on TiAl3 Formation in Al Alloy/TI Bilayer Films During Annealing
Authors: Brown Dirk D. , Besser Paul R. , Sanchez John E. , Korhonen Matt A. , Li Che-Yu
Published: April 2011

Interconnect metallizations used in advanced integrated circuits typically use an Al-alloy sputterdeposited onto a Ti barrier layer. The Ti and Al react above ∼ 400°C to form TiAl3, which affects the stress evolution of the metal stack during thermal cycling. This paper describes results of thin film experiments performed on Ti/Al-alloy bilayer films. Two Al alloys were studied: Al-I%Cu and Al-0.5%Cu-1%Si. The rate of TiAl3 formation at 430°C was determined for both alloys and used to relate TiAl3 formation to the stress evolution of the film stacks during thermal cycling. The dominant effect of the TiAl3 intermetallic formation on stress arises from a change in the stress-temperature behavior of the film stack, due to a change in the yield behavior, effective modulus, and thermal expansion coefficient of the stack. The presence of Si in the Al-alloy markedly reduces both the rate of TiAl3 formation and the resulting change in composite stress.
Elastic Properties of Thin Films
Authors: White B. E. , POHL R. O.
Published: April 2011

A technique has been developed for characterizing the disorder present in thin films through the measurement of their low temperature internal friction. The technique utilizes a substrate, in the form of a double paddle oscillator etched from a high purity silicon wafer, onto which the thin film of interest can be deposited. The oscillator possesses an internal friction of 3 × 10−8 at 4 K which is reproducible to within 1% upon thermally cycling to room temperature. This extremely small substrate internal friction coupled with the excellent reproducibility permits measurements of the internal friction of very thin amorphous films, with a 2 tun silica film producing a change in the internal friction of 4 × 10−9. By performing low temperature internal friction measurements on thin silica films with thicknesses ranging from 2 nm to 1000 nm, we have investigated the role of interacting defects in determining the universal nature of the anomalous low temperature thermal and elastic properties of amorphous solids. We have found no evidence for strong interactions between these tunneling defects. Other applications of the oscillator include monitoring of the crystallization of amorphous films through changes in the low temperature internal friction, internal friction measurements and vapor pressure measurements of quenched condensed rare gas solids and amorphous water ice, and internal friction studies of amorphous solids which can only be produced in thin film form.
On Separating Bonding Strength From Film and Substrate Properties
Authors: He Jia-Wen , Hendrix B. C. , Yi Mao-Zhong , Hu Nai-Sai
Published: April 2011

Bonding strength is commonly measured by various kinds of single cycle tests such as scratch tests or indentation tests. These tests all reflect complex composite properties - both plastic and elastic properties of the film and the substrate - as well as the bonding strength. In many cases experimental critical value of these single cycle tests is controlled by film or substrate strength or ductility rather than bonding strength. In these cases, the single cycle test should be evaluated in terms of the specific property which controls failure and should not be taken as a measure of “bonding strength.” However, the interfacial fatigue strength measured at 5X106 cycles is shown to be measurable over a large range of bonding strengths and composite properties. And further, this interface fatigue strength is insensitive to the composite properties. The complementary nature of these two types of tests is demonstrated for various TiN-based hard coatings on various steel and cemented carbide substrates.
Dielectric, Pyroelectric, and Thermal Properties of Solid Solutions of Ba (Ti,Zr)O3,Ba(Ti,Hf)03, Ba(Ti,Sn) 03 and (Ba,Nd)TiO3
Authors: Deb K. K.
Published: April 2011

Modified BaTiO3 ceramics are candidate materials for infrared sensors in nightvision equipment. Measurements of dielectric constants, dielectric losses, pyroelectric coefficient, and heat capacities as functions of temperature and frequency are performed. Crystallographic and grain size data are also presented. It is shown that additions of these impurities to BaTiO3 alters the temperature of phase transformations and, with it, dielectric and pyroelectric properties. The results of these measurements were compared with those of PZT and PbTiO3 ceramics, which are currently the favoredmaterials for uncooled detector arrays, as well as PbTiO3 and PZT thin films. It is concluded that these oxide ceramics offer the combination of preparative ease of property modification and show good performance at low impurity concentrations.
Modelling of Polydomain Smart Materials
Authors: Yu Yongsik , Roytburd Alexander
Published: April 2011

Polydomain materials with periodic (modulated) domain structures are of potential practical importance since they can possess unique and desirable mechanical and physical properties. A twin related domain formation can be a result of constrained structural, ferroelectric or ferromagnetic transformations. The thermodynamic theory on the deformation of layer composites containing a polydomain (polytwin) ferroelectric component is analyzed. The deformation of the layer composite under different directional electric fields and constraints is calculated.
A New Superfluid Leak Tight Low Temperature Valve Using a Magnetostrictive Actuator
Authors: Hahn Inseob , Barmatz M. , Clark A.
Published: April 2011

Low temperature valves play an important role in many research and development applications. Conventional low temperature valves primarily use actuation mechanisms depending on either gas or mechanical pressure. These actuation mechanisms usually require inconvenientoperating procedures such as a gas handling system or manual operation. We developed a superfluid leak tight low temperature valve that can be activated by a magnetostrictive material. All that is required to activate this magnetostrictive valve is a magnetic field produced by a simple power supply and coil. This new valve consists of separate valve and actuator units. The valve unit is designed to be normally closed using a spring. The stemof the valve is made of a hard 440c stainless steel ball while the seat uses a softer 304 stainless steel.
Thermo-Mechanical Ni50Ti50/Si Composite Thin Film Switch
Authors: Kim T. , Su Quanmin , Wuttig Manfred
Published: April 2011

The mechanical properties of Ni50Ti50 deposited on Si and 3C-SiC substrates were studied focussing on the interaction of the film and substrate. This interaction determines the transformation characteristics through interface accommodation and mechanical constraints exerted by the substrate stiffness. Substrate stiffness, controlled by the film/substrate thickness ratio, was found to have a substantial influence on the output energy of the film/substrate composite. A switch type composite based on this knowledge was fabricated and tested.
Properties of Piezoelectric Pzt Thin Films for Microactuator Applications
Authors: Damjanovic D. , Brooks K. G. , Kholkin A. , Kohli M. , Maeder T. , Muralt P. , Setter N.
Published: April 2011

The piezoelectric properties of lead zirconate titanate (PZT) thin films deposited on thick silicon substrates and thin silicon membranes were investigated using optical interferometry. The effect of the geometrical constraints and clamping effects on the piezoelectric response is discussed. The study of the dielectric permittivity and the loss as a function of the amplitude of the alternating electric field reveals that extrinsic contributions to the dielectric permittivity become active at large fields. The DC electric field has the effect of freezing out the extrinsic contributions. The influence of the dielectric loss on the piezoelectric properties is discussed.
Present and Future Applications of Shape Memory and Superelastic Materials
Authors: Duerig T.W.
Published: April 2011

The utility of superelastic Ni-Ti alloys in the medical industry has been rather dramatically demonstrated in recent years. A great number of devices are now in production, and still others are staged to enter production during the next few years. This surge in interest from the medical community stems from an increased acceptance of Ni-Ti because of its biocompatibility, advances in micromachining techniques and trends towards less-invasive surgical techniques. In addition, there are a variety of new developmental concepts that will have a major influence on this and other markets during the next 5 years of commercialization. This review will highlight many of the properties of Ni-Ti by illustration in a variety of recent medical applications, and then discuss some of the newer developmental concepts. Medical applications that will be presented here include guidewires, laparoscopic surgical instruments, implants, stents, retrieval baskets, and bone anchors. Some of the new concepts and capabilities that are reviewed include microvalves made from thin films, high temperature alloys, fatigue resistant composites, and robotic actuators with tactile feedback.
Phase Stability and Site Substitution in NB-AL Compounds
Authors: Sluiter M. , Takahashi M. , Kawazoe Y.
Published: April 2011

The site preferences of Ta, Mo, and W in A15 Nb3Al, the phase stability of off-stoichiometric A15 Nb3Al, and the atomic order of the Nb2Al D8b (σ) phase are investigated by performing electronic structure calculations based on the local density approximation. Mo, W, and Ta are found to have a preference for the Nb sublattice. Ta has the strongest site preference. It was shown that some recently proposed ground states for off-stoichiometric A15 phases are unlikely to occur in the Nb-Al system. Moreover, it was shown that the atomic order in the D8b Nb2Al phase contributes significantly to its stability.
The C14-to-C15 Transformation in Cr2Hf
Authors: Kumar K. S. , Hazzledine P. M.
Published: April 2011

Three alloys, single-phase Cr2Hf, a two-phase alloy consisting of Cr solid solution and Cr2Hf, and a two-phase alloy consisting of Hf solid solution and Cr2Hf were cast and heat treated. The C14-to- C15 transformation of the Laves phase, Cr2Hf was studied as a function of heat treatment. According to the existing phase diagram, the Cr2Hf phase exhibits a C14 structure at elevated temperature but transforms to the C15 structure at lower temperatures. Such transformations are known to be extremely sluggish. In the present study, the Cr2Hf phase was found to retain the C14 structure at room temperature in all three compositions in the cast or cast and forged conditions; upon subsequent heat-treatment at various temperatures and time-at-temperatures, however, the C14 structure decomposes to a variety of higher order structures including the 16H, 10H, and 4H structures. These superstructures can be viewed as containing various percentages of the cubic and hexagonal stacking. The C15 structure was not observed for any of the conditions considered.