bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tribological Properties of Ti/Tin Nanomultilayers
Authors: Houdy Ph. , Psyllaki P. , Labdi S. , Suenaga K. , Jeandin M. 
Published: April 2011

AbstractThe tribological behaviour of Ti/TiN amorphous nanometric multilayers is reported in comparison with that of single Ti and TiN layers, in order to study the wear mechanism of nanostructures submitted to that one may call “macroscopic loading”. Ti/TiN nanolayers were deposited onto Si substrate by high vacuum diode r.f. sputtering assisted by in-situ kinetic ellipsometry. Transmission Electron Microscopy (T.E.M.) characterization exhibited the multilayered structure of the films, ascertained by grazing angle X-ray reflectometry and ellipsometry. Sliding wear tests against alumina in dry air showed the ceramic-typed behaviour of the multilayers, the wear of which was partly governed through a microfracture mechanism. Their wear lifetime was found to be higher than that of Ti and TiN single layers and increased with the number of layers.
Indenter Geometry Effects on The Measurement of Mechanical Properties by Nanoindentation with Sharp Indenters
Authors: Tsui T. Y. , Oliver W. C. , Pharr G. M. 
Published: April 2011

AbstractThe measurement of mechanical properties by nanoindentation methods is most often conducted using indenters with the Berkovich geometry (a triangular pyramid) or with a sphere. These indenters provide a wealth of information, but there are certain circumstances in which it would be useful to make measurements with indenters of other geometries. We have recently explored how the measurement of hardness and elastic modulus can be achieved using sharp indenters other than the Berkovich. Systematic studies in several materials were conducted with a Vickers indenter, a conical indenter with a half-included tip angle of 70.3°, and the standard Berkovich indenter. All three indenters are geometrically similar and have nominally the same area-to-depth relationship, but there are distinct differences in the behavior of each. Here, we report on the application of these indenters in the measurement of hardness and elastic modulus by nanoindentation methods and some of the difficulties that occur.
In-Situ Tem Investigation During Thermal Cycling of thin Copper Films
Authors: Keller R.-M. , Sigle W. , Baker S. P. , Kraft O. , Arzt E. 
Published: April 2011

AbstractIn-situ transmission electron microscopy (TEM) was performed to study grain growth and dislocation motion during temperature cycles of Cu films with and without a cap layer. In addition, the substrate curvature method was employed to determine the corresponding stresstemperature curves from room temperature up to 600°C. The results of the in-situ TEM investigations provide insight into the microstructural evolution which occurs during the stress measurements. Grain growth occurred continuously throughout the first heating cycle in both cases. The evolution of dislocation structure observed in TEM supports an explanation of the stress evolution in both capped and uncapped films in terms of dislocation effects.
Simultaneous Overall and Local Stress Analysis of Thin Metal Films by Light Scattering and Beam Deflection Measurements
Authors: Kylner C. , Mattsson L. 
Published: April 2011

AbstractWe have developed an optical instrument for real-time overall stress as well as local stress relaxation measurements. The physical principle of the instrument is based on the fact that when a sample is exposed to heating the overall film stress bends the substrate and hillocks, the evidence of the local stress relaxation, form on the surface. Early hillock formation can be observed in real-time with integrated scattering technique, but the overall stress can be readily observed by laser beam deflection. Our instrument integrates laser beam deflection and light scattering techniques to achieve simultaneous overall stress and local stress relaxation measurements. A stress study is presented for an aluminium thin film on a silicon substrate.
Thin Film Polymer Stress Measurement Using Piezoresistive Anisotropically Etched Pressure Sensors
Authors: Bitko G. , Harries R. , Matldn J. , McNeil A. C. , Monk D. J. , Shah M. , Wertz J. 
Published: April 2011

AbstractSilicon bulk micromachined piezoresistive pressure sensors are very sensitive to applied stresses: that is, applied pressure and/or packaging-related stresses. Device encapsulation has been observed to affect the electrical output of the pressure sensor significantly. The magnitude of the zero applied pressure output voltage (i.e., the offset voltage) that can be attributed to a thin film encapsulant is proportional to the magnitude of the roomtemperature thermal stress of that film. Parylene C coatings have been used as encapsulants in this work. Finite element and analytical modeling techniques were used to evaluate the effect of material property variation on the offset of a pressure sensor. A simple, linear expression of offset as a function of a material property parametric group, that includes: parylene thickness, parylene biaxial modulus, parylene CTE, silicon thickness, and annealing temperature; has been established. Experimental analysis of parylene coated pressure sensors and parylene coated silicon and gallium arsenide wafers was performed to confirm the resulting model. Known variations in parylene material properties caused by processing (i.e., uncontrolled deposition, annealing, and high temperature storage) have been used as an experimental vehicle for this purpose. An empirical relationship between offset voltage on parylene coated devices and room-temperature thermal stress on parylene coated wafers that have been exposed to the same processing is a linear expression with a similar slope to the modeling results. Furthermore, stress measurements from parylene coated silicon wafers and parylene coated gallium arsenide wafers have been used to estimate the parylene biaxial modulus (approximately 5000 MPa) and the parylene CTE (approximately 50 ppm/°C) independently. These material properties were observed to shift following parylene annealing and high temperature storage exposure experiments in a manner that is consistent with the established model.
Determination Of The α-Al2O3(0001) Surface Relaxation and Termination by Measurements of Crystal Truncation Rods
Authors: Guenard P. , Renaud G. , Barbier A. , Gautier-Soyer M. 
Published: April 2011

AbstractWe have investigated the unreconstructed (0001) surface structure of sapphire (α-Al2O3) by Grazing Incidence X-ray Scattering. Modulations along the crystal truncation rods were analyzed in order to determine the chemical nature of the terminating plane, and the structural relaxations of the first few atomic planes below the surface. The most likely model yields a single Al layer termination with relaxations of the first four planes of -51%, +16%, -29% and +20% respectively. These results compare well with the most recent theoretical calculations on this surface.
Near-Edge X-Ray Absorption Fine Structure Examination of Chemical Bonding in Sputter Deposited Boron and Boron-Nitride Films
Authors: Jankowski A.F. , Jimenez I. , Hayes J.P. , Shuh D.K. , Tong W.M. , Sutherland D.G.J. , Carlisle J.A. , Terminello L.J. , Himpsel F.J. 
Published: April 2011

AbstractNear-edge x-ray absorption fine structure (NEXAFS) is used to examine the chemical bonding in boron and boron-nitride films sputter deposited from a fully-dense, pure boron target. Reactive sputtering is used to prepare the boron-nitride and multilayered films. Although the process of sputter deposition often produces films that lack long range order, NEXAFS reveals the distinguishing features of sp2 and sp3 hybridization that are associated with different crystalline structures. The sensitivity of NEXAFS to local order further provides details in bonding modifications that exist in these films.
Resonance Photoemission at the 2p Excitation Threshold of Ni3Al
Authors: HSU Li-Shing , Tsang K.-L. , Chung S.-C. 
Published: April 2011

AbstractA marked resonance enhancement of the 3d photoemission intensity in angle-integrated electron-distribution curves from Ni3Al has been observed 6.6 eV below the Fermi level for photon energies in the vicinity of the Ni 2p absorption threshold. Soft x-ray L-edge absorption spectra were measured to determine the Ni 2p excitation threshold. The Fano asymmetry parameter and the effective Coulomb interaction for Ni3Al are 2.2 and 4.8 eV, respectively, as derived from the experimental data. Differences between the 2p→3d and the 3p→3d resonance effect are discussed, and comparisons with Ni, NiAl, and NiGa are made.
X-Ray Microscopy Of Multiphase Polymeric Materials
Authors: Ade H. , Smith A. P. , Zhuang G. R. , Wood B. , Plotzker I. , Rightor E. , Liu D.-J. , Lui S.-C. , Sloop C. 
Published: April 2011

AbstractWe have utilized the scanning transmission x-ray microscope at Brookhaven National Laboratory to acquire high energy resolution spectra of various polymers and to investigate the bulk characteristics of multiphasic polymeric materials with chemical sensitivity at a spatial resolution of about 50 nm. We present studies ranging from phase separated liquid crystalline polyesters and polyurethanes to various polymer blends. Improvements in the NEXAFS imaging and spectral acquisition protocol in the recent past provide much improved spectral fidelity and include in situ energy calibration with CO2.
Structure and Morphology of MBE Fabricated Zn0.5Fe0.5Se On GaAs as a Function of Substrate Preparation and Growth Temperature
Authors: Wei H.-Y. , Salamanca-Riba L. , Smathers J. , Jonker B. T. 
Published: April 2011

AbstractWe have recently reported the observation of CuAu-I, CuPt, and Cu3Au ordered structures in the diluted magnetic semiconductor Zn1−xFexSe grown by molecular beam epitaxy for different values of the Fe concentration. In the present work, we grew a series of samples with identical Fe composition (x=0.5) but for a range of growth temperatures (from 250 °C to 450 °C). By using transmission electron microscopy, ordering along the <001> and <110> directions was observed in both electron diffraction patterns and cross-sectional high-resolution lattice images corresponding to the CuAu-I ordered structure of Zn0.5Fe0.5Se. However, this ordered structure coexists with a tetragonal FeSe structure and forms large, well defined faceted domains. At the higher growth temperature, the number of faceted domains increases as observed by atomic force microscopy. Pure FeSe films were also grown at different temperatures for comparison. The influence of substrate preparation before film growth is also discussed.
Structural and Electrical Properties of Hgx Zn1−x S Thin Films Prepared by Flash Evaporation Technique
Authors: Swain P. K. , Sehgal H. K. , Misra D. 
Published: April 2011

AbstractElectron diffraction investigations carried out on flash evaporated mercury zinc sulphide films with mercury concentration ( atomic percentage, x ) in the range 0.16 ≤ x ≤ 0.84 grown on freshly cleaved single crystal KCl substrates maintained at temperatures (Ts) between 65°C and 225°C indicate the films grow as single phase ternary alloy films with b.c.c. structure. Presence of a single phase alloy of the type HgxZn1−xS in the films is corroborated by a single absorption edge observed in the optical absorption measurements. The lattice parameter varies between 5.26Å and 4.52 Å as ‘x’ is varied between 0.16 and 0.84. The lattice parameter is observed to decrease slightly with increase of Ts for all compositions. The average grain size is observed to increase between 0.020 microns and 0.058 microns with increase of Ts in all films. Results of room temperature d.c. resistivity measurements show the resistivity to decrease with increase in mercury concentration ‘x’ in the films at a given Ts; ( for ‘fs=225°C, ρ(x=0.16) = 100.6 Ω-cm and ρ(x=0.84) = 10−0.4 Ω-cm ). The resistivity of films with a particular mercury concentration is, however, observed to increase with increase in the substrate temperature; ( for x=0.84 film, typical resistivity values are, ρ(Ts = 65 C) =10−2 Ω-cm and ρ(Ts = 225 C) = 10−0.4 Ω-cm). The observed resistive behavior of the films hints towards predominant grain boundary conduction in the films.
Transmission Electron Microscopy Stjudy of Initerface Microstrucure in ZnO Thin Films Grown on Various Substrates (Glass,Au,Sl,α-Al2O3)
Authors: Yoshino Y. , Iwasa S. , Aoki H. , Deguchi Y. , Yamamoto Y. , Ohwada K. 
Published: April 2011

AbstractZinc oxide (ZnO) thin films have been grown by radio frequency sputtering on glass, Al, Au and R cut sapphire substrates. Microstructures of the ZnO / substrate interface have been observed by transmission electron microscope. The purpose of this study is to elucidate the crystal growth mechanism of ZnO thin films using various substrates that have different crystallinity and crystal structures. An amorphous layer with a thickness of about 5 nm is observed at the ZnO/glass interface, and c axis orientation perpendicular to the substrate is observed on this amorphous layer. Mianstructurts at the ZnO/buffer metal interface, on the other hand, are significantly different from those of ZnO/glass interface. A thick amorphous layer of about 15 nm is observed at the ZnO/Al interface, presumably consisting of Al2O3 interface layer material. ZnO thin film grown on Au buffer layers is distinctly different from both ZnO on glass and Al. No amorphous layer is formed at the ZnO/Au interface, and c axis orientation begins directly from the Au surface. Epitaxially grown ZnO thin film is confirmed on a R-cut sapphire substrate. These results dearly demonstrate that ZnO thin films prepared by radio frequency sputtering are strongly influenced by the substrate surface crystallinity at the topmost layer of the substrate.
Structural and Chemical Properties of MBE Grown Niobium Overlayers on (110) Rutile
Authors: Marien J. , Wagner T. , Rühle M. 
Published: April 2011

AbstractThin Nb films were grown by MBE in a UHV chamber at two different temperatures (50°C and 950°C) on the (110) surface of TiO2 (rutile).At a growth temperature of 50°C, reflection high energy electron diffraction (RHEED) revealed epitaxial growth of Nb on rutile: (110)[001] TiO2 ¦¦ (100)[001] Nb. In addition, investigations with Auger electron spectroscopy (AES) revealed that a chemical reaction took place between the Nb overlayer and the TiO2 substrate at the initial growth stage. A 2 nm thick reaction layer at the Nb/TiO2 interface has been identified by means of conventional transmission electron microscopy (CTEM) and high-resolution transmission electron microscopy (HRTEM).At a substrate temperature of 950°C, during growth, the Nb film was oxidized completely, and NbO2 grew epitaxially on TiO2. The structure and the chemical composition of the overlayers have been investigated by RHEED, AES, CTEM and HRTEM. Furthermore, it was determined that the reaction of Nb with TiO2 is governed by the defect structure of the TiO2 and the relative oxygen affinities of Nb and TiO2.
Study on Thermal Stability of Thin CoSis Film
Authors: Gu Zhi-Guang , Chu Paul K. , Liu Jing , Jiang Guo-Bao , Ru Guo-Ping , Li Bing-Zong 
Published: April 2011

AbstractThe thermal stability of thin CoSi2 films formed from four layered structures: Co/Si, TiN/Co/Si, Co/Ti/Si and TiN/Co/Ti/Si has been studied using four-point-probe (FPP), TEM and RBS/channeling. It is found that thermal instability can be influenced by the polycrystalline structure in CoSi2. Growing epitaxial CoSi2 film on Si (100) using TiN capping and Ti interfacial layers can improve the thermal stability of thin CoSi2 film.
Stress and Microstructural Evolution of Lpcvd Polysilicon Thin Films During High Temperature Annealing
Authors: Yu Chia-Liang , Flinn Paul A. , Lee Seok-Hee , Bravman John C. 
Published: April 2011

AbstractThe mechanisms of stress generation and stress relaxation of LPCVD silicon thin films were studied using high temperature wafer curvature measurements. The stresses generated during depositions are measured as functions of deposition temperature and microstructure. Amorphous silicon deposited with a compressive stress shows a large stress change toward tensile during crystallization. The stress relaxation of polysilicon films deposited with tensile stresses can be described by a deformation model from Ashby and Frost [1]. The polysilicon films deposited with compressive stresses have hydrogen incorporated during deposition and shows hydrogen evolution during thermal cycles.
Monte Carlo Modeling of Atom Transport During Directed Vapor Deposition
Authors: Groves J. F. , Wadley H. N. G. 
Published: April 2011

AbstractAtomic vapor transport has been investigated in the low vacuum (5 – 100 Pa) supersonic gas jets encountered in directed vapor deposition processes using a combination of Direct Simulation Monte Carlo (DSMC) techniques and a bimolecular collision model. The DSMC code generates the velocity vector, pressure, and temperature field for the carrier gas flow. This data is used as an input to a bimolecular collision model of atomic vapor transport in the flow. In the collision model, calculation of directed momentum loss cross-sections allows the location of carrier gas/vapor atom collisions to be deduced, and the vapor atom velocity vectors for individual vapor atoms to be tracked from source to substrate. For atoms arriving at the substrate, the impact location and velocity vector are obtained, making possible calculation of deposition efficiency, film thickness, adatom energy, and impact angle. These are the key inputs for simulations of resulting film microstructure/morphology evolution. Preliminary results for atomic transport of Cu vapor in supersonic He flows compare favorably with previously reported experimental observations.
Scanning Transmission X-Ray Microscopy Study of TiSe2/NbSe2 Superlattices
Authors: Shin Hyun-Joon , Jeong Kwangho , Johnson David C. , Kevan Stephen D. , Noh Myungkeun , Warwick Tony 
Published: April 2011

AbstractTiSe2/NbSe2 superlattices crystallized from elementally modulated films have been studied with a Scanning Transmission X-ray Microscope (STXM) at the Advanced Light Source. The samples exhibited structures in the plane of the film with sizes of the order of one micrometer. The chemical sensitivity of STXM allowed us to infer that the titanium in the superlattice exists predominantly in microcrystalline TiSe2, but that these microcrystals are interspersed with elemental titanium inclusions. The STXM images reflect the interfacial nucleation between the constituent layers characteristic of the kinetic trapping method.
Photolumineseence, Electroluminescence, and Cathodoluminescence of ZnO:Zn Phosphor Films Prepared by MOCVD
Authors: Li Y. , Forsythe E. , Tompa G. S. , Liu J. , Morton D. C. 
Published: April 2011

AbstractCathode ray tube (CRT) technology remains the major display component for today's display technologies. The improvements from monochrome displays to today's full color displays have always been accompanied by improvements in the phosphors. The CRT type displays operate at very high voltages (over 10 keV) at relatively low currents, a few microamps/cm2. The phosphors and phosphor coating technology used in CRT based displays have been optimized for operation with these excitation conditions. However, the developments of field emitter displays based on microtip technology, or negative electron affinity technology require phosphors that operate at lower voltages, preferably 10 to 1500 eV at relatively higher current densities. Zn-rich zinc oxide (ZnO:Zn) powders have shown improved low voltage cathodoluminescence (CL) as compared to conventional ZnS based phosphors. ZnO:Zn thin film phosphors for cathodoluminescent displays, compared to conventional powder phosphors, can have the advantages of high electrical and thermal conductivity, high energy saturation limit, and high screen resolution. The photoluminescence (PL), Electroluminescence (EL), and CL from thin ZnO:Zn films were studied. The samples were prepared by Low Pressure Metal Organic Chemical Vapor Deposition (LP MOCVD) and post-annealed at temperatures from 700 °C to 1000 ° C. The PL, EL, and CL spectra have a peak centered at 590 nm that increases with annealing temperatures up to 1000 °C. The CL efficiencies are 0.12 Lm/W at electron voltages and currents as low as 500 V and 64 mA/cm2. The ZnO films have been characterized by X-ray Diffiractometry (XRD), and Sweep Electron Microscope (SEM). These PL, EL, and CL results from ZnO:Zn films show the promise for improved phosphors to meet Field Emitting Device (FED) challenges.
Morphology and Quantitative Nitrogen Impurity Measurements in Homoepitaxial Chemical Vapor Deposited Diamond
Authors: Catledge S. A. , Vohra Y. K. , Yan C. , Tohver H. T. 
Published: April 2011

AbstractA thick (130 im) homoepitaxial diamond film was grown on a polished, single crystal {100} oriented natural type Ila diamond circular plate using high density microwave plasma chemical vapor deposition (MPCVD). The as-grown film shows facets around its perimeter, approaching the form of a cubo-octahedral crystal. The plate dimensions increased from 1.50 mm diameter and 0.25 mm thickness to 1.64 mm diameter and 0.38 mm thickness, corresponding to a growth rate of nearly 11 μm per hour. The substrate temperature during growth was approximately 900 C. The film was characterized by optical microscopy, Raman spectroscopy, photoluminescence spectroscopy (PL), and electron paramagnetic resonance (EPR) before and after deposition. The surface morphology of the as-grown film shows large growth steps and a few scattered penetration twins. The diamond film is transparent except for localized regions containing the twin defects. Raman spectroscopy shows a strong diamond peak at 1332 cm−1 superimposed on a background fluorescence. A broad Raman band at 1550 cm−1 is present on the surface defects and is indicative of an amorphous network of sp2-bonded carbon. The luminescence of the film reveals the presence of a nitrogen-vacancy pair. The homoepitaxially-grown diamond layer also exhibits the P1 substitutional nitrogen impurity with a concentration of 8 parts per million (ppm) as determined by EPR. No nitrogen impurities were detected in the original substrate before deposition. EPR is also used to confirm the single crystal nature of the grown diamond.
Growth of Cubic SiC Thin Films on Silicon from Single Source Precursors by Supersonic Jet Epitaxy
Authors: Boo Jin-Hyo , Ustin Scott A. , Ho Wilson , Maruska H. Paul , Norris Peter E. , Kim Ig-Hyeon , Sung Changmo 
Published: April 2011

AbstractCubic SiC thin films have been grown by supersonic jet epitaxy of single molecular precursors on Si(100), Si(111) and Separation by IMplanted OXygen (SIMOX) silicon on insulator (SOI) substrates at temperatures in the range 780 - 1000 °C. Real-time, in situ optical reflectivity was used to monitor the film growth. Films were characterized by ellipsometry, x-ray diffraction (XRD), and transmission electron microscopy (TEM). Monocrystalline, crack-free epitaxial cubic SiC thin films were successfully grown at 830 °C on carbonized Si(111) substrates using supersonic molecular jets of dimethylisopropylsilane, (CH3)2CHSiH(CH3)2, and diethylmethylsilane, (CH3CH2)2SiHCH3. Highly oriented cubic SiC thin films in the [100] direction were obtained on SIMOX(100) at 900 °C with dimethylisopropylsilane and on Si(100) at 1000 °C with diethylmethylsilane. A carbonized Si(100) surface was found to enhance SiC deposition from diethylmethylsilane at a growth temperature of 950 °C.