bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anisotropic Behaviour of Surface Roughening in Lattice Mismatched Heteroepitaxial Thin Films
Authors: Ozkan Cengiz S. , Nix William D. , Gao Huajian 
Published: April 2011

AbstractHeteroepitaxial Si1-xGex. thin films deposited on silicon substrates exhibit surface roughening via surface diffusion under the effect of a compressive stress which is caused by a lattice mismatch. In these films, surface roughening can take place in the form of ridges which can be aligned along <100> or <110> directions, depending on the film thickness. In this paper, we investigate this anisotropic dependence of surface roughening and present an analysis of it. We have studied the surface roughening behaviour of 18% Ge and 22% Ge thin films subjected to controlled annealing experiments. Transmission electron microscopy and atomic force microscopy have been used to study the morphology and microstructure of the surface ridges and the dislocations that form during annealing.
Anomalous X-Ray Scattering On Sr and Sr-Eu Metaphosphate Glasses
Authors: Bionducci M. , Meneghini C. , Navarra G. , Licheri G. , Balerna A. , Mobilio S. 
Published: April 2011

AbstractThe results of an Anomalous X-ray Scattering experiment performed on Sr(PO3)2 and Eu0.1Sr0.9(PO3)2.1 glasses are presented. These are the first measurements carried out on GILDA (General purpose Italian beamLine for Diffraction and Absorption) diffractometer, located at the European Synchrotron Radiation Facility (ESRF), Grenoble. To obtain detailed information about the local order on pure and Eu-doped Sr-metaphosphate glasses both samples were investigated near the Sr K-edge (16.107 KeV), while the latter was also studied near the Eu K-edge (48.517 KeV).
X-Ray Truncation Rod Analysis Of Cu Thin Films on C-Plane Sapphire
Authors: Chung K.S. , Hong Hawoong , Aburano R.D. , Roesler J.M. , Chiang T. C. , Chen Haydn 
Published: April 2011

AbstractThe interfacial structure of room-temperature MBE-grown Cu thin film on c-plane sapphire has been studied by measuring the substrate crystal truncation rod (CTR) using synchrotron radiation. One substrate was annealed in air at 1500°C for 3 hours followed by an anneal in UHV at 1200°C for 30 minutes prior to Cu deposition. CTR from a clean sapphire substrate without Cu coverage was measured as a reference. The annealed substrate showed higher diffracted intensity along the CTR due to changes in surface structure. The terminating sequence of the substrate surface layers have been obtained from intensity profile analysis.
Characterization of Diamond Thin Films by Core-Level Photoabsorption and UV Excitation Raman Spectroscopy
Authors: Zuiker C. D. , Krauss A. R. , Gruen D. M. , Carlisle J. A. , Terminello L. J. , Asher S. A. , Bormett R. W. 
Published: April 2011

AbstractNear-edge x-ray absorption fine structure (NEXAFS) and Raman spectroscopies have been used to characterize both nanocrystalline and faceted, microcrystalline diamond thin films grown by microwave plasma chemical vapor deposition under a variety of conditions. Raman spectroscopy is perhaps the most commonly used method of characterizing diamond film quality, whereas photoabsorption requires a synchrotron radiation source and is much less commonly used. Both methods characterize the sp2 (graphitic) /sp3 (diamond) electronic bonding character of the films, but Raman spectroscopy is considerably more sensitive to sp2 than sp3 bonded carbon. For nanocrystalline diamond, the use of a visible excitation source for Raman spectroscopy also gives rise to an intense fluorescence band which may completely mask the sp3 Raman line, even in films with negligible (<1%) sp2 bonding character. Near-edge x-ray absorption fine structure (NEXAFS) is a more localized measurement of the electronic bonding character, and does not have as large a variation in sensitivity between sp2 and sp3 phases.Raman spectra measured using 632.8 nm light exhibit a sharp diamond phonon peak at 1332 cm−1 for faceted, large grain diamond films, and no obvious diamond phonon peak for the nanocrystalline diamond films. However, Raman spectra excited by 228.9 nm light exhibit a sharp diamond phonon peak for both nanocrystalline and large grain, faceted diamond films. The UV Raman results are consistent with the C(ls) NEXAFS measurements which show clear bulk diamond excitonic and sp3 features, with little evidence of sp2 character for all of the tested films. We conclude that the use of visible excitation Raman spectroscopy as the sole criterion for the assessment of quality in nanocrystalline diamond films is misleading, but that UV Raman spectroscopy and NEXAFS provide a consistent and reliable characterization. Nanocrystalline films grown using a fullerene precursor in an Ar microwave plasma with very low levels of hydrogen (2%) are found by both of the latter methods to consist almost entirely of sp3-bonded carbon with ˜2% non-tetrahedral bonding.
XANES Studies at N and C K-Edge of Compounds in the Ternary System Si-C-N
Authors: Kroll P. , Greiner A. , Riedel R. , Bender S. , Franke R. , Hormes J. , Pavlychev A. A. 
Published: April 2011

AbstractWe report on XANES-investigations at the nitrogen and carbon K-edge of Si-C-N containing solid phases prepared by the reaction of silicon tetrachloride with bis(trimethylsilyl)carbodiimide and annealing the reaction product at temperatures between room temperature (RT) and 1600°C. From the spectra it is possible to evidence the evolution of four phase regions and their different structural increments. We can relate the observed changes of atomic excitations to chemical and structural effects. By that means proposed structural models for the different phases are testified.
Chemical Speciation by NEXAFS Spectromicroscopy: Insights from Molecular Modelling of Polymers
Authors: Urquhart S. G. , Hitchcock A. P. , Rightor E. G. , Smith A. P. , Ade H. 
Published: April 2011

AbstractNear Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy of polymers performed in a scanning transmission X-ray microscope (STXM) can provide chemical speciation with <0.1 gm spatial resolution in imaging mode. The core excitation spectra of molecular compounds that are structural analogues of polymers help interpret the NEXAFS spectra of polymers. The effect of nt-delocalization on polymer NEXAFS is discussed and illustrated by comparison to molecular spectra. Extended Htickel calculations are particularly useful for providing insight into the relationship between chemical structure and the molecular and polymer spectra. We report the interpretation of experimental NEXAFS spectra of polyethylene terephthalate (PET). Molecular models indicate that NEXAFS will be sensitive to structural isomerization in polyester polymers. We demonstrate the capability of NEXAFS to distinguish hard-segment and soft-segment phase segregation in polyurethanes.
Evidence for a Structural Origin of Perpendicular Magnetic Anisotropy in PtxCo1−x Thin Film Alloys
Authors: Tyson T. A. , Conradson S. D. , Farrow R. F. C. , Jones B. A. 
Published: April 2011

AbstractXAFS analysis of the local structure about Pt and Co in PtxCo1−x, for x ˜ 0,7 revealed that the local coordination of Co and Pt is similar to that found in cubic L12 Pt3Co. In the plane of the films, significant Co-Co bonding was found- a feature not present in ordered L12 Pt3Co. The presence of Co-Co bonds, preferentially in-plane, suggest that clustering of Co into “sheets” or “chains” is the source of PMA in these films.
Temperature Dependence of the Mcxd at the GD Lm Edge
Authors: Gofrono K. J. , Kimball C. W. , Lee P. L. , Jennings G. , Montano P. A. 
Published: April 2011

AbstractAn energy dispersive spectrometer is used to measure the temperature dependence of the Magnetic Circular X-ray Dichroism (MCXD) effect at the gadolinium (Gd metal) LIII absorption edge from 94 K to 335 K. In ferromagnetic Gd, the MCXD spectrum consists of the main positive peak with pre- and post-edge features. Only the main positive peak exhibits a temperature dependence similar to that of Gd magnetization. All other features decrease as the temperature increases and vanish slightly above the transition temperature (293 K). Well above the ordering temperature (paramagnetic Gd), the MCXD consists only of the positive peak, with a post-edge background that slowly decays away from it over a range of 90 eV.
In Situ Tem Analysis of TiSi2 C49-C54 Transformations During Annealing
Authors: Gignac L. M. , Svilan V. , Clevenger L. A. , Cabral C. , Lavoie C. 
Published: April 2011

AbstractIn situ transmission electron microscope (TEM) observations of TiSi2 C49-to-C54 phase transformations were recorded on video tape and photographic negatives, and transformation front velocities (vTF) were measured from the data. The samples studied in this work include: C49-TiSi2 blanket films and 0.2 μm wide, 7 mm long lines on undoped poly-Si and 0.13 μm wide, 10 μm long lines on either B- or As-doped poly-Si. The in situ TEM analysis showed that blanket TiSi2 films on undoped poly-Si fully transformed at 830°C and had an average vTF of 0.5 ± 0.2 μm/s. The transformation occurred from a sparse nucleation density of ˜0.1 site/μm2. The 0.2 μm wide lines transformed at temperatures greater than 885°C, and the average vTF was 1.1 ± 0.2 μm/sec. Agglomeration started for both the blanket film and the 0.2 μm wide lines at temperatures above 900°C. In situ x-ray diffraction (XRD) analyses of C49-TiSi2 on B- and As-doped poly-Si showed that blanket films completely transformed to C54-TiSi2 at T = 835–843°C, but 0.13 μm wide, varying length lines did not fully transform, even when rapid thermal annealed to 1025°C. From in situ TEM analysis of 0.13 μm wide, 10 μm long C49-TiSi2 lines on B-doped poly-Si, a distinct transformation was not observed. Instead, the lines slowly agglomerated, and electron diffraction of the agglomerated regions showed that the film had transformed to C54-TiSi2. An individual line either 1) completely transformed and agglomerated or 2) remained as C49-TiSi2 and did not agglomerate. Approximately 85% of all lines transformed. In situ TEM analysis of 0.13 μm wide, 10 μm long lines of C49-TiSi2 on As-doped poly-Si also showed an indistinct transformation to the C54 phase along with agglomeration, and 100% of the lines transformed.
Comparison of the Hafnium Diboride(0001) and Hafnium(0001) Surfaces
Authors: Belyansky M. , Trenary M. , Otani S. , Tanaka T. 
Published: April 2011

AbstractThe surface properties of the (0001) surfaces of single crystals of hafnium and hafnium diboride are compared with a boride film deposited on the Hf(0001) surface. The surfaces were characterized with X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED). Boron deposition was achieved through the thermal decomposition of diborane. The deposited boron reacts with the hafnium substrate to form HfB2 as determined by XPS and the HfB2 films were found to be epitaxial as determined by LEED. The epitaxial nature of the thin films was confirmed with X-ray diffraction. The epitaxial thin films of HfB2 on Hf(0001) display properties identical to those of the HfB2(0001) single crystal surface.
Laser and Thermal Annealing Modification of Diamond-Like Atomic-Scale Composite Films Studied by Micro Raman Spectroscopy
Authors: Wan J. Z. , Pollak Fred H. , Dorfman Benjamin F. 
Published: April 2011

AbstractWe have modified the properties of diamond-like atomic-scale composite (DLASC) material of various thicknesses (5 μm – 70 μm) by means of (a) cw Ar-ion laser annealing using a focussed beam (˜ 2 μm spot size) and (b) thermal annealing (400°C≤ T ≤800°C for one hour). These DLASC films [amorphous “diamond-like/quartz-like” a-(C:H/Si:O)] constitute a novel class of diamond-related materials. The annealing effects were investigated by micro-Raman scattering. The laser annealing procedure shows that the structure of these films can be altered locally from amorphous to nano-crystallite depending not only on the parameters of the annealing process (annealing time, laser intensity) but also the mechanical properties (hardness and stress) of the DLASC films.
Effect of Non-Hydrostatic Stress on Kinetics and Interfacial Roughness During Solid Phase Epitaxial Growth in Si
Authors: Barvosa-Carter William , Aziz Michael J. 
Published: April 2011

AbstractWe report preliminary in-situ time-resolved measurements of the effect of uniaxial stress on solid phase epitaxial growth in pure Si (001) for the case of stress applied parallel to the amorphous-crystal interface. The growth rate is reduced by the application of uniaxial compression, in agreement with previous results. Additionally, the velocity continues to decrease with time. This is consistent with interfacial roughening during growth under stress, and is supported by both reflectivity measurements and cross-sectional TEM observations. We present a new kinetically-driven interfacial roughening mechanism which is consistent with our observations.
Interface Of Aluminum/Ceramic Power Substrates Manufactured By Casting-Bonding Process
Authors: Ning X. S. , Ogawa Y. , Suganuma K. 
Published: April 2011

AbstractNew processes for manufacturing Al/ceramic power substrates have been developed. These processes use a casting-bonding method to bond Al plates to the both sides of ceramic plates. The Al plates formed on the substrates are then chemically etched to be a desired shape using the conventional technology, followed by plating nickel on them. The power substrates manufactured by the process have both a perfect interface and an excellent thermal stress tolerance. Hence, these processes are especially suitable for assembling high reliability power devices such as IGBT power modules.
New Packaging Substrate Technology,Ibss (Interpenetrating Polymer Network Build Up Structure System)
Authors: Asai Motoo 
Published: April 2011

AbstractWe have developed a new type of printed circuit board which is called “IBSS” (Interpenetrating polymer network Build up Structure System) for the purpose of meeting the demand of high density routing, high reliability and low cost substrates in IC packages. The new technology achieves 50μm line / 50μm space and 100μm diameter photo‐via hole. Full additive method is applied for patterning, and the build‐up method is used to form the multi‐layer structure. The newly developed photo‐imagable dielectric resin, “IPN”, which has a glass transition of 200'C, a copper peel strength of 1.5kg/cm, and withstands 1000 cycles of temperature cycling (TCB), is used for IBSS. IPN is composed of high heat resistant photo‐sensitive epoxy and supper engineering plastic. This IBSS technology is suitable for direct chip attachment. This paper presents the characteristics IBSS.
The Effect Of Orientation On Electrically Conducting Polymer Composite Properties
Authors: Genetti W. B. , Grady B. P. , O'Rear E. A. 
Published: April 2011

AbstractConductive polymer matrix composites have been a focus of research for the past 30 years, due to applications such as electromagnetic shielding. The electrical resistance of these materials can be broken into three major categories: the intrinsic resistance of the filler and matrix, the particle‐particle contact resistance, and the tunneling resistance. Both the particle‐particle contact and tunneling resistance in nickel filled low density polyethylene (LDPE) composites can be reduced by the addition of an ultrathin polypyrrole (PPy) coating on the nickel surface. Coating the nickel particles with PPy leads to increases in conductivity as much as three order of magnitude at concentrations well above the percolation threshold without significantly changing the mechanical properties. We believe at concentrations above the critical region PPy forms “molecular wires” reducing the loss of conductivity associated with the uniaxial orientation of the polymer matrix.
A Conversion-Electron Mssbauer Study of Tin-Based Compounds Formed During Pads Treatment (Plasma-Assisted Dry Soldering) of a Solder Foil
Authors: Reno Robert C. , Piekarski Brett 
Published: April 2011

AbstractWe have used conversionelectron Mössbauer spectroscopy (CEMS) to examine the surfaces of solder foils treated in a plasma assisted dry soldering (PADS) system which has been developed1 to convert surface oxides to more desirable fluorides in order to protect the solder surface prior to assembly and to eliminate the need for flux during the soldering process. CEMS samples only the outer 1 μm of a solder foil and this, coupled with the fortuitous fact2 that Mössbauer spectroscopy is 10–20 times more sensitive to oxides and fluorides than to the metallic form of solder, means that surface layers of oxides and fluorides as thin as 10 nm can be detected and chemically identified. We have followed the evolution of surface layers produced in PADS treatments ranging from 7 minutes to several hours. Our results show that fully treated foils contain surface layers of SnF2 and Sn2F6. Partially treated foils also contain some SnO2 and perhaps a small amount of SnO. No Sn2OF2 or SnF4 was produced during any portion of the PADS treatment cycle.
Electromagnetic Interference Shielding Reaching 130 Db Using Flexible Graphite
Authors: Xiangcheng Luo D.D.L. Chung 
Published: April 2011

AbstractElectromagnetic interference (EMI) shielding effectiveness reaching 130 dB at 1 GHz was achieved by using flexible graphite (Grafoil). Due to the resilience of flexible graphite, it is particularly attractive as an EMI gasket. The high shielding effectiveness is due to the large specific surface area and large skin depth. In contrast, the shielding effectiveness was only 90 dB for polycrystalline graphite of low specific surface area.
Multilayer Composite Diamond Heat Spreaders for Electronic Packaging
Authors: Jagannadham K. , Fan W. D. , Dinwidde R. B. , Narayan J. 
Published: April 2011

AbstractHeat spreader characteristics of single layer and multilayer diamond composite substrates are determined by bonding to electronic device wafers. Preparation of diamond substrates, metallization and bonding procedures to device wafers are described. Infrared microscopy imaging of the bonded device wafers is used to determine the heat spreading characteristics. Advantages associated with multilayer diamond composite heat spreaders are discussed.
Mcm Development Using Fine Pitch Ball Bump
Authors: Dohya Akihiro , Morisaki Ikushi , Bonkohara Manabu , Nakamura Hirofumi 
Published: April 2011

AbstractA fine-pitch ( less than 100 micro-meter pads pitch ) aluminum pad flip chip assembly technology for use with the built-up Printed Wiring Boards (PWB) has been developed and named “Lead-Less-Chip Assembly (LLC Assembly)” technology. Our newly developed technology consists of three points: Forming gold-ball-bumps on the aluminum pads of the bare LSI chip by a wire ball bonding method. Solder-coating on the copper pads of the built-up PWB using Micro Punching technology or the Super-Juffit technology. Flux-less solder bonding the bare chip onto the PWB with a nitrogen atmosphere.A reliability evaluation performed on a single chip and multi chip modules assembled using this LLC Assembly technology with test chips and real C-MOS devices showed a high level of endurance. We have applied this technology to Multichip modules (MCMs) for Note Personal Computers and portable terminals.
Pulsed Excimer Laser Processing of AlN/GaN Thin Films
Authors: Wong W. S. , Schloss L. F. , Sudhir G.S. , Linder B. P. , Yu K-M. , Weber E. R. , Sands T. , Cheung N. W. 
Published: April 2011

ABSTRACTA KrF (248 nm) excimer laser with a 38 ns pulse width was used to study pulsed laser annealing of AIN/GaN bi-layers and dopant activation of Mg-implanted GaN thin films. For the AIN/GaN bi-layers, cathodoluminescence (CL) showed an increase in the intensity of the GaN band-edge peak at 3.47 eV after pulsed laser annealing at an energy density of 2000 mJ/cm2. Rutherford backscattering spectrometry of a Mg-implanted A1N (75 nm thick)/GaN (1.0 μm thick) thin-film heterostructure showed a 20% reduction of the 4He+ backscattering yield after laser annealing at an energy density of 400 mJ/cm2. CL measurements revealed a 410 nm emission peak indicating the incorporation of Mg after laser processing.
Thermal Stability of Pt, Pd, and Ni on GaN
Authors: Duxstad K. J. , Haller E. E. , Yu K.M. , Hirsch M. T. , Imler W. R. , Steigerwald D. A. , Ponce F. A. , Romano L. T. 
Published: April 2011

ABSTRACTThe development of reliable Ohmic and Schottky contacts on GaN will require an understanding of the thermal stability and metallurgy of metal-GaN contact structures. We investigated the behavior of Pt, Pd, and Ni on GaN as a function of annealing temperature. Rutherford backscattering spectrometry, x-ray diffraction, and scanning electron microscopy were used to characterize the interface and surface behavior. 800Å thin metal films were deposited by sputtering on 2μm GaN films grown by metal organic chemical vapor deposition on sapphire substrates. No reactions occur in the Pt, Pd, and Ni systems with annealing up to 800°C. The Pt film begins to form submicron spheres and islands after annealing above 600°C. The Pd and Ni films begin to island with annealing above 700°C. Below these temperatures no structural changes were observed.
Cr/Ni/Au ohmic contacts to the moderately doped p- and n-GaN
Authors: Kim Taek , Yoo Myung C. , Kim Taeil 
Published: April 2011

ABSTRACTWe report new Cr/Ni/Au and Ni/Cr/Au tri-layer metallization schemes for achieving low resistance ohmic contacts to moderately doped p- (∼1 × 1017/cm3), and n-GaN (∼1 × 1018/cm3) respectively. The metallizations were thermally evaporated on 2 μm-thick GaN layers grown on c-plane sapphire substrates by metalorganic chemical vapor deposition (MOCVD). Comparisons with bi-layer metallizations such as Ni/Au and Cr/Au were also made. The Cr/Ni/Au contacts showed a low specific contact resistivity of 9.1 × 10−5 Ω⋅cm2 to n-GaN while that of Ni/Cr/Au to p-GaN was 8.3 × 10−2 Ω⋅cm2. The Ni/Cr/Au contacts also showed a low specific contact resistivity of 2.6 × 10−4 Ω⋅cm2 to n-GaN. The Ni/Cr/Au metallization could made reasonable ohmic contacts to p- and n-GaN simultaneously
Structural and Optical Properties of Nitride-Based Heterostructure and Quantum-Well Structure
Authors: Amano H. , Takeuchi T. , Sota S. , Sakai H. , Akasaki I. 
Published: April 2011

ABSTRACTStructural and optical properties of nitride based heterostructure and quantum well structure were investigated. Both AIGaN and GaInN ternary alloys are found to grow coherently on the underlying GaN layer. Compressive strain of GaInN is found to cause quantum confined Stark effect, thus affects the luminescence properties of nitride-based quantum wells.
GaN-Based MSM uv Photodetectors
Authors: Liang S. , Cai W. , Li Y. , Liu Y. , Lu Y. , Tran C.A. , Karlicek R.F. , Ferguson I. 
Published: April 2011

ABSTRACTResults obtained from interdigital metal-semiconductor-metal (MSM) type of GaN based UV photodetectors are presented. MSM devices were fabricated using two types of GaN; high-resistive GaN and Mg doped GaN. For the high-resistive GaN detector, the lowest dark current is ∼0.1 nA and the UV responsivity of the device was about 460 AAV at a DC bias of 30 V. The Mg doped GaN exhibited large gains, 1150 A/W at 2.0 V, but at much higher dark currents, 400 nA. The high gain in this device is not well understood but was attributed to an ‘avalanche’ effect and is under investigation. It was found that the surface plasma treatment plays an important role in the device performance. After an appropriate plasma treatment the detectors showed higher responsivity with lower dark current.