bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Semi-Empirical Methodology to Study Bulk Silica System
Authors: Chen Ai , Corrales L. René 
Published: April 2011

AbstractA semi-empirical methodology [1,2] developed to model and simulate covalently bonded networked systems is modified to study the heteroatomic mixtures of silica. This methodology is capable of grasping the essential qualitative and quantitative features of the coupling between the electronic coordinates and the geometric structure. The methodology is used to simulate and to probe the structural and thermodynamic properties of the bulk crystalline, amorphous solid and the melt states of silica.
Triboemission And Wear Of Hydrogenated Carbon Films
Authors: Nakayama Keiji 
Published: April 2011

AbstractIt is suggested that perfluoropolyether lubricating oil coatings applied to the carbon overcoat film of magnetic recording layers become decomposed by electrons emitted from frictional surfaces. However, no work has at yet been reported as to triboemission of electrons from frictional carbon films.This paper describes the behavior of triboemission of electrons and the friction coefficient during wear of sputtered hydrogenated carbon films (with various hydrogen contents on the glass substrate). The triboemission of electrons, together with friction coeficient, was measured in a frictional system of Al2O3 sliding on carbon films in a reduced dry air atmosphere. The worn surfaces of the carbon films were then observed using both a SEM and an AFM. The results showed that intense triboemission of electrons were observed during wear of hydrogenated carbon films. The electron emission intensity and friction coefficient transit from low to high with hydrogen content in the film. These results are discussed including physical properties of the carbon films such as internal stress and surface wettability.
Thermal Expansion of β-Sic, Gap and Inp
Authors: Reeber Robert R. , Wang Kai 
Published: April 2011

ABSTRACTThermal expansion is important for predicting residual stresses in epitaxial films, composites and electronic devices as well as for providing information relevant to an understanding of interatomic potentials and the equation of state of materials. Model calculations have many assumptions, both inherent and implicit, and have difficulty accurately representing thermal expansion at high temperatures and pressures. We utilize a semi-empirical quasi-harmonic model to evaluate available data for β-silicon carbide, gallium phosphide and indium phosphide. The model allows prediction of the thermal properties of these semiconductors from near 0 K to the vicinity of their melting points. The approach, consisting of a simplified frequency spectrum with several Einstein terms, provides a convenient mathematical method where a minimum of empirical parameters represent the thermal property.
A Fetish for Gallium Arsenide
Authors: Barron Andrew R. 
Published: April 2011

ABSTRACTAn overview of the development of a new dielectric material, cubic-GaS, from the synthesis of new organometallic compounds to the fabrication of a new class of gallium arsenide based transistor is presented as a representative example of the possibility that inorganic chemistry can directly effect the development of new semiconductor devices. The gallium sulfido compound [(tBu)GaS]4, readily prepared from tri-tert-butyl gallium, may be used as a precursor for the growth of GaS thin films by metal organic chemical vapor deposition (MOCVD). Photoluminescence and electronic measurements indicate that this material provides a passivation coating for GaAs. Furthermore, the insulating properties of cubic-GaS make it suitable as a the insulating gate layer in a new class of GaAs transistor: a field effect transistor with a sulfide heterojunction (FETISH).
Synthesis and Oxidation Kinetics of Sol-Gel and Sputtered Tantalum Nitride Thin Films
Authors: Kraus Gerald T. , Oldweiler Cory S. , Giannelis Emmanuel P. 
Published: April 2011

ABSTRACTTantalum nitride thin films were produced by nitridation of sol-gel tantala thin films. The oxidation kinetics and the activation energy for oxidation were investigated and compared to those of sputtered tantalum nitride thin films. Data was gathered from in situ sheet resistance measurements taken between 550 and 720 K. Sol-gel films exhibited parabolic oxidation kinetics and had an activation energy of 1.9 eV. Sputtered films displayed quartic oxidation kinetics at lower temperatures tending toward cubic kinetics at higher temperatures and had an activation energy of 1.6 eV.
Real Time Ellipsometric Study of Boron Nitride Thin Film Growth
Authors: Bertran E. , Canillas A. , Campmany J. , Kasmi M. El , Pascual E. , Costa J. , Andújar J. L. 
Published: April 2011

ABSTRACTWe present anin situstudy of the growth of boron nitride thin films by real time ellipsometry. Films were produced in a PECVD reactor by rf glow discharge decomposition of ammonia (pure) and diborane (1% in hydrogen), on Ni-Cr coated c-Si substrates placed either on the powered electrode or on the grounded electrode of the reactor. A fast phase-modulated ellipsometer performed the real time monitoring of the growth processes at 350 nm. The ellipsometric angle trayectories were obtained through an autocalibrated method, especially suitable for thein situoptical analysis of transparent thin films. We applied several thin film growth optical models (homogeneous, two-layer, surface roughness) to analyze parameters of the films such as refractive index, extinction coefficient, roughness and deposition rate. In all the cases studied, the two-layer model fits well with the ellipsometric measurements, but a more sofisticated model considering a variable refractive index could better describe these films.
Passivation of Si(100)2×l Surfaces With Elemental Sulfur
Authors: Papageorgopoulos Aris 
Published: April 2011

ABSTRACTDeposition of elemental S on Si(100)2×1 surfaces at room temperature changes the reconstructed Si(100)2×1 to its original bulk-terminated Si(100)l×l surface. Sulfur forms initially a (2×l) on the Si(100)2×l surface and subsequently a (l×1) on the Si(100)l×l. Above 1ML, sulfur is diffused into the Si bulk near the surface. The sticking coefficient of S on Si(100) surface is constant up to 2 ML. Deposition of S at RT up to 1 ML increases the work function of the surface by about.3±0.05 eV. Above I ML, as the S is diffused into the Si bulk, the work function decreases.
P-type Doping of SIC by Aluminum Implantation for Advanced Device Applications
Authors: Caleca Maria A. , Du Honghua , Flemish Joseph R. , Withrow Stephen P. 
Published: April 2011

ABSTRACT6H-SiC epitaxial layers with a background n-type dopant concentration of 1 × 1016/cm3 were hot implanted to doses ranging from 4.0 × 1013 to 1.8 × 1014 Al ions/cm2 at 65, 135, and 220 keV to achieve a box-type implant distribution to a depth of 300 nm. Electrical activation of dopants was carried out using a proximity annealing method at 1500°C in a buffer environment to retard surface degradation of the SiC samples. Measurements using atomic force microscopy illustrated the morphological stability of the SiC surface during the high-temperature annealing. Transmission line measurements showed some degree of dopant activation. Characterization of fabricated p-n junction diodes demonstrated p-type conduction in the aluminum-implanted SiC samples.
In Vivo Evaluation of Pulsed Laser Deposited Hydroxyapatite Coating for Prosthesis-Bone Bonding
Authors: Cotell C. M. , Conklin J. A. , Auyeung R. C. Y. , Wong S. S. , Klapperich C. M. , Spector M. 
Published: April 2011

AbstractThe bone-implant bond strength to hydroxyapatite-coated cylindrical Ti-6A1–4V implants was evaluated in torsional tests using a canine model. Experimental hydroxyapatite (HA) coatings were deposited using pulsed laser deposition (PLD) under conditions that yield highly crystalline, phase-pure coatings on Ti-6A1–4V. Commercially available plasma-sprayed (PS) HA coatings of lower crystallinity and purity served as positive controls (for bone bonding) and uncoated polished and grit-blasted Ti-6A1–4V samples as negative controls. The torsional shear strength of the PLD HA-coated specimens implanted in cancellous bone was substantially lower than that of the PS HA-coated implants, at both 2 and 6 weeks post-implantation. Within statistical limits, the shear strength of the PLD HA-coated samples was similar to that of the polished Ti-6A1–4V control implants and lower than the grit-blasted Ti-6A1–4V control implants. Examination of PLD HA-coated samples after mechanical testing revealed many areas from which the coating had detached. Previous results from laboratory solubility studies showed that (a) PLD films released less calcium and phosphate than the PS controls, (b) rates of dissolution were much lower and (c) the PLD coatings contained fewer decomposition products. Taken with these previous findings, the present results suggest that the surface morphology and/or grain size of implants may be more important for bone bonding than the phase purity of hydroxyapatite coatings. Furthermore, the local chemical environment resulting from the dissolution of the more soluble phases present in the PS HA coatings may enhance bone bonding.
Electric Field Mediated Deposition of Bioactive Polypeptides on Neural Prosthetic Devices
Authors: Buchko Christopher J. , Kozloff Kenneth M. , Sioshansi Atisa , O'shea K. Sue , Martin David C. 
Published: April 2011

AbstractWe have developed processing schemes for depositing three-dimensionally tailored layers of protein polymers on a variety of solid substrates. One of our goals is to create stable, biocompatible coatings on silicon devices for implantation in the central nervous system. Our research has identified several candidate coatings whose morphologies lie in the biologically significant 0.1 to 100 micrometer length scale. Using electric field mediated deposition, we are able to process polypeptides into biologically-responsive films and coatings. Quantitative analysis of the structural evolution of the coating enables us to fine-tune its morphology by varying the field strength and geometry or solution concentration. The interaction of the coated substrates with neurons and glial cells are examined in vivo and in vitro. Data collected from light optical microscopy, atomic force microscopy, transmission electron microscopy, and scanning electron microscopy provide insight about the relationship between the microstructure of these coatings and their macroscopic properties.
A Symposium Overview: Surface Properties of Implant Materials
Authors: Meyer A. E. 
Published: April 2011

AbstractLike most thriving human endeavors, the field of implant materials and devices intersects with a universe of populations and professions. Nearly everyone will “get into the act” in one way or another, resulting in a variety of perspectives that have more, or less, foundation in fact and genuine concern for the patient. Even the scope of the points of view of scientists and engineers is relatively broad. One reason for the richness of the field in which we work is the increasing number of sites in the body to which implants are being delivered for the treatment of disease and replacement or augmentation of natural tissues. Another reason is the diversity of materials used in implants and diagnostic devices.
Formation of Stacked Self-Assembled InAs Quantum Dots in GaAs Matrix for Laser Applications
Authors: Ustinov V. M. , Egorov A. Yu. , Zhukov A. E , Ledentsov N. N. , Maksimov M. V. , Tsatsul'nikov A. F. , Bert N. A. , Kosogov A. O. , Kop'ev P. S. , Bimberg D. , Alferov Zh. I. 
Published: April 2011

AbstractVertically coupled InAs quantum dots have been synthesized by MBE through successive deposition of InAs dot sheets and thin GaAs spacers. The energy of ground state transition in PL spectra has been found to depend on a number of dot sheets and the spacer width. Injection laser based on vertically coupled quantum dots demonstrated lasing via the ground state of quantum dots in the entire 80K-300K temperature range. Lower threshold current density and wider range of the thermal stability of threshold current density as compared to the single sheet quantum dot laser have been observed.
Optical Properties of Ordered Gainp
Authors: Ernst P. , Geng C. , Hahn G. , Scholz F. , Schweizer H. , Zhang Yong , Mascarenhas A. 
Published: April 2011

AbstractWe use the information from low temperature PLE spectra measured on a set of samples with different degree of order for an investigation of the correlation between the order dependent valence band splitting and band gap reduction. The experimental values are compared with predictions from recent ab initio band structure calculations.Moreover, we show how the low temperature optical properties of ordered GaInP2 are related to the microstructure of the material. We find a close correlation between the size of the ordered domains and the relative intensity of the intrinsic PL-peak from excitonic recombination compared with the rapidly shifting, below band-gap luminescence emission.
Spontaneous Lateral Modulations in InAlAs Buffer Layers Grown by MBE on InP Substrates
Authors: Peiró F. , Cornet A. , Ferrer J. C. , Morante J. R. , Halkias G. , Georgakilas A. 
Published: April 2011

AbstractTransmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) have been used to analyze the spontaneous appearance of lateral composition modulations in InyAl1−yAs (yIn.≅ 50%) buffer layers of single quantum well structures grown by molecular beam epitaxy on exact and vicinal (100) InP substrates, at growth temperatures in the range of 530°C–580°C. The influence of the growth temperature, substrate misorientation and epilayer mismatch on the InAlAs lateral modulation is discussed. The development of a self-induced quantum-wire like morphology in the In0.53Ga0.47As single quantum wells grown over the modulated buffers is also commented on.
Dependence of Optical Properties of Semiconductor Alloys on Long Range Order, Strain and Pressure
Authors: Wei Su-Huai , Franceschetti Alberto , Zunger Alex 
Published: April 2011

AbstractMany III – V semiconductor alloys exhibit spontaneous (111) alternate monolayer ordering when grown from the vapor phase. We have studied theoretically the ordering induced changes in the optical properties of the semiconductor alloys. We describe (i) the change of the band gap ΔE9, and the valence band splitting ΔE12 as functions of the long range order parameter η, (ii) the consequence of coexistence of (001) epitaxial strain and (111) chemical ordering on the optical properties, (iii) optical anisotropy and spin polarization effects in the ordered alloy, (iv) theory of reflectance-difference spectroscopy in ordered alloy, and (v) the ordering-induced changes on high energy E1 and E2 transitions. Specific, experimentally testable predictions are listed in the summary section.
Atomic Ordering of III-V Alloy Semiconductors Grown on (110)InP and its Influence on Electron Mobility
Authors: Ueda O. 
Published: April 2011

AbstractAtomic ordering in InGaAs, InAlAs, and GaAsSb crystals grown on (110) InP substrates by molecular beam epitaxy, has been studied by transmission electron microscopy. In the electron diffraction pattern from these crystals, superstructure spots associated with CuAu-I type ordered structure are found. When the tilting angle of the substrates increases, the ordering becomes stronger. The ordering is also stronger in crystals grown on substrates tilted toward the <001> or the <001> direction than those on substrates tilted toward the <110> direction. From these results, one can conclude that atomic steps on the growth surface play an important role in the formation of ordered structures. The ordering becomes stronger when the growth temperature increases. In high resolution images of the crystal, doubling in periodicity of 220 and 200 lattice fringes is found, which is associated with CuAu-I type ordered structure. Moreover, anti-phase boundaries are very often observed in the ordered regions. It is also found that ordering is not perfect, and that ordered regions are plate-like microdomains lying on planes slightly tilted from the (110) plane. On the basis of these results together with considerations of the atomic arrangement of the ordered structure and surface reconstruction on the (110) plane, we propose four possible models for the ordering. Through precise evaluation of these models, two models are selected as the most probable ones: these involve formation of the ordered structures on surfaces dominated by two monolayer steps. These models have been experimentally proven by the analyses of electron diffraction patterns from different InGaAs crystals grown on different growth surfaces. We have fabricated InGaAs/N-InAlAs heterostructures with a strongly ordered InGaAs channel layer. The measured two-dimensional electron gas mobilities from these structures are found to be 100,000 cm2/Vs in the <110> direction and 161,000 cm2/Vs in the <110> direction with a sheet electron concentration (Ns) of 9.5 × 1011 cm−2 at 6 K. The latter mobility is much higher than both calculated alloy scattering limited mobility and the best experimental results for lattice-matched InGaAs/N-InA]As systems. The mobility enhancement in the <110> direction is considered to be achieved by the suppression of alloy scattering due to the occurrence of ordering in the InGaAs channel layer.
InGaAs/GaAs Strained-Layer QW Vertical Cavity Surface Emitting Laser Structures grown on GaAs (311)A Substrates by MBE
Authors: Takahashi M. , Vaccaro P. , Fujita K. , Watanabe T. 
Published: April 2011

AbstractWe report the crystal growth conditions and lasing characteristics of InGaAs-GaAs strained-layer quantum well vertical cavity surface emitting lasers (VCSELs) grown on GaAs(311)A substrates by molecular beam epitaxy. A significantly smooth surface and high reflectivity of more than 99 % were achieved. Very flat and dislocation-free AlAs/GaAs hetero-interfaces were obtained. Furthermore, a very low threshold of 5.5 mA and current density of 270 A/cm2 have been achieved for the first time under CW operation at room temperature. In addition, we demonstrate stable polarization characteristics at high currents. These results are believed to be a consequence of both the predicted high gain and anisotropic gain distribution on the (311) surface.
Stable Visible Photoluminescence from Annealed Polysiloxene-Based Thin Films
Authors: Miyazaki S. , Mouraguchi A. , Shinohara M. 
Published: April 2011

AbstractPolysiloxene-based films have been prepared by plasma enhanced CVD in a Si2H6+O2 gas mixture at a substrate temperature of −110°C and annealed at temperatures from 700°C to 1000°C. It is found that the film annealed at 1000°C is composed of 1∼5nm Si crystallites embedded in SiO2 and exhibits stable, intense visible-luminescence at room temperature under 488nm excitation. The temperature and excitation power dependences of the steady-state and timeresolved luminescence of the annealed films suggest the radiative recombination through localized states in the Si/SiO2 interface region.
Post Epitaxial Disordering of CuPtB Ordered AIGaInP/GaInP for Microstructuring
Authors: Bukard M. , Englert A. , Geng C. , Scholz F. , Schweizer H. 
Published: April 2011

AbstractLateral order/disorder structures have been fabricated out of ordered GaInP quantum wells by ion implantation.Using high resolution electron beam lithography for definition of implantation masks, we achieve wire structures down to 35nm width. Implantation was carried out at energies down to 25keV and doses from 3e10cm−2 to 6e13cm−2. The so created vacancies lead to a reduction of the disordering temperature threshold of about 850°C for mere thermal disordering. Annealing those structures at 800°C results in selective disordering in the unmasked regions. We have ordered wire structures within disordered barriers. Even for the smallest mask widths of 35nm, the PL emission of wires and barriers are well resolved.
Cu Films on Si(100) by Partially Ionized Beam Deposition
Authors: Koh Seok-Keun , Kim Ki-Hwan , Han Sung , Jang Hong Gui , Jung Hyung-Jin 
Published: April 2011

AbstractHighly (111) oriented Cu films with a thickness around 1800 Å were prepared on Si (100) at room temperature by partialy ionized beam deposition (PIBD) at pressure of 8 × 10-7 - 1 × 10-6 torr. Effects of acceleration voltage (Va) between 0 and 4 kV on such properties as crystallinity, surface roughness, resistivity, etc. of the films have been investigated. The Cu films deposited by PIBD had only (111) and (200) planes and the relative intensity ratio, 1(111)/I(200), of the films increased from 6.8 at Va=0 kV to 37 at Va=4 kV. There was no indication of impurities in the system from AES analyses. A large increase in grain size of the films occurred with Va up to Va– 1 kV, but little increase occurred with Va>lkV. Surface roughness of the films at the ionization potential of 400 V decreased with Va, and resisivity had the same trends as that of the surface roughness. In the Cu films made by PIBD, it appears that changes of resistivity are mainly due to a surface scattering rather than a grain boundary scattering. The via holes, which is of 0.5. μm diameter x 1.5 μm deep, in the Cu films made at Va=4 kV, were completely filled without voids. Adhesion of the Cu film on Si(100) deposited at Va=3 kV was 5 times greater than that of Cu film deposited at Va=0 kV, as determined by a scratch test.
Integration of Al-Fill Processes for Contacts and VIAS
Authors: Barth H. J. 
Published: April 2011

AbstractToday different Al-fill techniques are used for the fill of submicron contacts and vias. The integration aspects of the most promising approaches, Al-reflow, cold/hot Al-planarization and high pressure Al-fill (Forcefill) are compared to the widely used W-plug technique. The filling properties are discussed with respect to future applications in ULSI devices. Special attention is given to the barrier stability in contacts and the influence on patterning. Various electrical data and reliability results are compared to metallizations with W-plugs. The implications of the Al-fill processes on chip design, especially on the size and shape of holes, the pattern density, the possibility of producing stacked contacts/vias and the metal to contact/via overlap are considered also. In an outlook for future developments, e.g. the introduction of low k dielectrics, the inverse metallization architecture with (dual) damascene interconnects and the emerging Cu metallizations, Alfill processes are facing new challenges which will be discussed.
Gas Cluster Ion Beam Processing for ULSI Fabrication
Authors: Yamada I. , Matsuo J. 
Published: April 2011

AbstractUnique characteristics of gas cluster ion beam bombardment are discussed in terms of ULSI fabrication processes. Cluster ion beams consisting of a few hundreds to thousands of atoms have been generated from various kinds of gas materials. Multi-collisions during the impact of accelerated cluster ions upon the substrate surfaces produce fundamentally low energy bombarding effects in a range of a few eV to hundreds of eV per atom at very high density. These bombarding characteristics can be applied to shallow ion implantation, high yield sputtering and smoothing, surface cleaning and low temperature thin film formation.