bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and Characterization of CdS Thin Films: Study of the adhesion of Il-VI compound semiconductors for applications to light emitting and absorbing devices
Authors: Kang Hyun Shik , Cho Gi Eun , Kim Kyung Wha , Persans Peter D.
Published: April 2011

The structural and optoelectronic properties of polycrystalline CdS films, fabricated by three different methods, are compared to one another for the purpose of preparing CdTe/CdS solar cells. The three methods were: alternated spraying of cation and anion solution at room temperature, spray pyrolysis, and chemical bath deposition. We studied the surface morphology and crystal quality and texture by scanning electron and optical microscopy and x-ray diffraction. All films had a well-developed wurtzite structure. Films grown by the alternated-spray method and the chemical bath method consist of randomly-oriented crystallites with dimensions <0.5 microns. Annealing at 400°C increases the crystallite size slightly. Films which were grown by pyrolysis at substrate temperatures from 400°C to 500°C were oriented in the <002> direction. For growth by pyrolysis at 500°C, the surface is rough on a lateral scale of 0.1 to 0.3 microns.
A Relationship between Interface Trap Density and Transconductance in 6H-SiC Enhancement Mode Field Effect Transistors
Authors: Dryfuse M. W. , Tabib-Azar M.
Published: April 2011

An explicit analytical expression relating the interface trap densities and transconductance is derived for enhancement mode field effect transistors without any simplifying assumptions regarding the energy distribution of traps. Using this relationship, the interface trap densities were calculated from transconductance data and compared to experimental data and that provided in the literature. Our expression provides a simple and convenient method to reliably estimate interface traps densities from the readily available transconductance data provided in the pertinent literature.
The Influence of Interface Traps on the High Frequency and High Temperature Performance of SiC Field Effect Transistors
Authors: Aydin H. , Dryfuse M. W. , Tabib-Azar M.
Published: April 2011

Fast and slow interface traps can considerably deteriorate the performance of field effect transistors. Slow interface traps, by slowly changing their charge occupancy, contribute to a drift in the quiescent operation point of the transistor, while fast traps deteriorate the device performance by contributing to both amplitude and phase current noise. They also result in a non-equilibrium surface depletion layer between gate and source which increases the gate-to-source parasitic resistance and deteriorates the device transconductance. We examine these different effects and present some preliminary data regarding interface traps in boron-doped 611-SiC.
The thermoelectric performance of silicon carbide semiconductor made from rice hull
Authors: A E. Maed , Komatsu M.
Published: April 2011

Thermoelectric properties (Thermoelectromotive force and electrical conductivity) of porous silicon carbide ceramics are evaluated. Porous silicon carbide ceramics are made from rice hull by reacting silica and carbon, both of which are included in rice hull, using hotpressing method[1].When nitrogen gas is used as enviromental gas for hotpressing, this material becomes n-type semiconductor. It shows comparably high themoelectromotive force. Thermoelectric properties of this material change with the processing conditions.The relationship between thermoelectric properties and microstructure is also evaluated.
Effects of Charged Substrates on Attachment of Primary Bone Marrow Stromal Cells
Authors: Qiu Q. , Sayer M. , Wan J. , Kawaja M. D. , Shen X. , Davies J. E.
Published: April 2011

The effects of charged substrates on the attachment of rat primary bone marrow stromal cells have been investigated using a novel cell culture chamber. Cells were cultured on the surfaces of a conductive and optically transparent indium tin oxide (ITO) coating. When a voltage was applied to the ITO electrodes, positive and negative charges were induced on the ITO electrodes. After 24 hours exposure to 0.8V, more cells attached to the anode than either the cathode or control both in presence or absence of serum in the culture medium. Protein desorption profiles also indicated that the enhanced attachment of cells to the anode was not controlled by the adsorption of serum proteins. The surface texture of ITO was analyzed using atomic force microscopy, the thickness by transmission electron microscopy, and crystallinity using glancing angle x-ray diffraction.
ESCA Detection of Surface Carboxyl Group Concentration of Polyanhydrides
Authors: Ciwen J.-X , Gardella J. A. , Santos C. A. , Mathiowitz E.
Published: April 2011

We present in this paper the surface derivatization of polyanhydrides with triethylamine for labeling the hydroxyl group. The reaction was verified with diffuse reflectance FTIR spectroscopy. Surface derivatization of poly(fumaric-co-sebacic)anhydride of 50:50 and 20:80 compositions was performed and ESCA measurements showed the surface nitrogen concentration in good agreement with stoichiometry values.
Does The 1.25 eV Luminescence of Coherently Strained InGaAs Insertions in GaAs Originate from Quantum Dots?
Authors: Lazzari J.-L. , Klann R. , Mazuelas A. , Trampert A. , Wassermeier M. , Brandt O. , Ploog K. H.
Published: April 2011

We study the growth of InAs/AlxGa1-xAs/GaAs heterostructures as well as their structural and optical properties. Structurally coherent InAs islands with a narrow size distribution are found to be formed only in a very narrow range of InAs coverage. In striking contrast, the photoluminescence band in the 1.15–1.35 eV spectral range, which is commonly attributed to the emission from InAs quantum dots, is present for all of our structures, regardless the presence or absence of InAs islands and their strain state. Moreover, for constant InAs coverage this PL band follows not the Γ gap but the L gap of the AlxGa1-xAs barrier. This latter result is in disagreement with effective mass calculations for three-dimensionally confined excitons.
Reversible Electrochromic Effect in Fullerene Thin Films Utilizing Alkali and Transition Metals
Authors: Konesky G. A.
Published: April 2011

A simple apparatus is described to rapidly assess the Electrochromic effect of Alkali and Transition Metal species of intercalated Fullerene thin films. Optical transmission loss during the Coloring phase is monitored at 880, 635, 583 and 565 nm while electrochemical intercalation proceeds. The process is repeated during the reverse polarity Bleaching phase. Results are presented for electrolyte systems based on Butyrolactone or water for Ag, Cr, Cu, Mg and Ba species.
Energy Up-Conversion at GaAs-GaInP2 and GaAs-AlGaInP2 Interfaces Caused by Cold Auger Processes
Authors: Driessen F. A. J. M. , Cheong H. M. , Mascarehas A.
Published: April 2011

Efficient, low-temperature luminescence at energies far above that of the exciting cw-laser is reported at junctions of GaAs-GaInP2 and GaAs-AlxGa1−x.InP2. The signal originates from the high-band gap layers and disappears only if the excitation energy is tuned below the GaAs band gap, as monitored by up-converted photoluminescence excitation spectroscopy. This shows that the non-linear process is induced by the generation of electrons and holes in the GaAs. Furthermore, it is found that the up-conversion is only observed if the (A1)GaInP2 layers are CuPtB long-range ordered. The reason for this is the inherent presence of metastable states in these ordered alloys. It is argued that cold Auger processes cause the nonlinear effect at these type I interfaces.
The Formation of Tin-Encapsulated Silver Films by Nitridation of Silver-refractory metal alloys in NH3
Authors: Adams Daniel , Alford T. L. , Laursen T. , Deng F. , Morton R. , Lau S. S.
Published: April 2011

Encapsulated Ag(Ti) films on oxidized silicon were obtained by nitridation of Ag(19 at.% Ti) alloys in NH3 at temperatures between 400-700°C for various times. Upon annealing Ti segregates to the surface and alloy/SiO2 interface to form a TiN(O) surface layer and a TiO/Ti5Si3 interfacial bilayer structure. Resistivity values of 2.5 μΩ-cm were measured in the encapsulated Ag alloys. The results suggest that resistivity is controlled by the residual Ti concentration.
Ti Salicide Technology using Nitrogen Diffusion from Tin Cap by RTA in an Argon Ambient
Authors: Ishigami T. , Matsubara Y. , Iguchi M. , Horiuchi T.
Published: April 2011

A new Ti salicide technology that uses nitrogen diffusion from a TiN cap layer by RTA in an argon ambient is demonstrated. The key point for achieving a fine-line Ti salicide iscontrolling the two competing reaction processes in thin Ti (<30 nm): nitridation at the Ti surface, and silicidation at the interface between Ti and Si. In the conventional Ti silicidation process using atmospheric nitrogen RTA, however, control of nitridation is difficult due to a high concentration of nitrogen at the Ti surface. Therefore, the remaining TiSi2 film is very thin and contains larger amount of nitrogen [1]. The new technology provides good controllability of Ti nitridation for thin Ti by using an argon atmospheric RTA.

A major advantage of nitrogen diffusion from a TiN cap layer is controllability of the nitrogen concentration at the interface between TiN and Ti. After TiN and Ti sputtering, silicidation was performed by two-step annealing in argon (RTA1: 680°C, 30 s; RTA2: 800°C, 10 s). When the thickness ratio (TiN/Ti) was 1, Ti2N formed on the field oxide. The Ti2N layer suppresses excessive silicidation over the field oxide in the same way that TiN does. Sheet resistance results show that silicidation is suppressed by the impurity effect in the case of thinner Ti (<20 nm). Furthermore, when TiN is thick (>20 nm), large metal strength retards silicidation [2]. Optimization of TiN/Ti thickness (20/20 nm) is essential for achieving low sheet resistance of 10 Ω for p+ and n+ quarter micron lines.
Rapid Thermal Chemical Vapor Formation of TiSi2: An alternative refractory metallization process for device fabrication
Authors: Gladden D. B. , Ren X. , Weintraub C. E. , Öztürk M. C.
Published: April 2011

Scaling of MOSFETs into the deep submicron regime requires novel metallization schemes to form low resistivity contacts on ultra-shallow junctions. In this paper, we present our recent results on rapid thermal chemical vapor formation (RTCVF) of TiSi2. In this process, the gaseous Ti source, TiCl4 (g), reacts with solid Si to form C54 TiSi2(s) at temperatures as low as 700°C with a resistivity of 15-20μΩ-cm without a follow-up anneal. In this paper, we explore the previously reported barrier for nucleation of TiSi2 on Si at temperatures below 800°C. Without proper surface preparation, this barrier results in an incubation time which can vary according to the conditions of the surface and the deposition environment. We show that contrary to general belief, surface morphology instead of surface cleanliness is the most likely contributor to this barrier. We also show that if in-situ deposition of a Si-Ge layer precedes TiSi2 formation, the incubation time can be completely eliminated. Experiments performed in a temperature range of 650°C - 800°C indicate an approximate activation energy of 100 kJ/mol. The process provides excellent selectivity to both SiO2 and Si3N4 and little growth rate dependence on patterns in the 2 μm - 200 μm regime.
Microscopic Driving Forces For Electromigration
Authors: Sorbello Richard S.
Published: April 2011

Electromigration in metals is due to microscopic forces acting on mobile defects. These microscopic forces arise from the local electric field that accompanies electron transport, and the resulting defect migration is a consequence of the dynamic response of the defect to this local field. Theoretical results are given for the local electric field and the electromigration driving force on impurities in bulk systems and in metallic microstructures where surfaces, grain boundaries and dislocations play an important role. Extensions of the theory are described for mesoscopic systems, and local heating is shown to be an important effect as the size of the system becomes smaller and the electron current is larger.
Structural, Textural and Catalytic Properties of Al-, Ti - Pillared Clays
Authors: Ramos-Galván C. E. , Dominguez J. M. , Sandoval-Robles G. , Castillo-Mares A. , Nava E N.
Published: April 2011

Al-, Ti- and Zr-pilared clays were characterized and NiMo/Pilc's were tested in HDS reactions. The combination of activity measurements with Mossbauer Spectroscopy and x-ray microanalysis at microscopical scale give insight in the metal phases migration during pillaring, reaction and regeneration steps. α-Fe phase in free Fe2O3 islands predominate together with structural Fe3+ phase, but during the catalytic reaction Fe2+ forms. Delamination of the Ti- and Zr-Clay supports, together with high Lewis acidity might enhance their catalytic properties.
Coadsorption of Nitriles and Co On Cu-Zsm-5: An In Situ FTIR Spectroscopic Study
Authors: Szanyi J. , Paffett M. T.
Published: April 2011

The coadsorption of acetonitrile (ACN) or deuterated acetonitrile (dACN) with CO at Cu-ZSM-5 reveals several interesting features concerning the partial valency of Cu. Specifically, CO binds at Cu+1 and Cu° centers (in the absence of preadsorbed ACN) and exhibits C-O stretching frequencies of 2157 cm−1 and 2112 cm−1, respectively. Carbon monoxide readily adsorbs at an ACN (or dACN) saturated Cu-ZSM-5 and exhibits a C-O stretch of 2122 cm−1, a value more consistent with a partially reduced Cu+1 center. Furthermore, the IR cross section for the CN stretch in a number of nitriles (ACN, dACN, and benzonitrile) coadsorbed with CO displays interesting effects attributed to rehybridization and changes in CN dipole moment.
Porous Silicon Structural Evolution from In-Situ Luminescence and Raman Measurements
Authors: Tallant D. R. , Kelly M. J. , Guilinger T. R. , Simpson R. L.
Published: April 2011

We performed in-situ photoluminescence and Raman measurements on an anodized silicon surface in the HF/ethanol solution used for anodization. The porous silicon thereby produced, while resident in HF/ethanol, does not immediately exhibit intense photoluminescence. Intense photoluminescence develops spontaneously in HF/ethanol after 18–24 hours or with replacement of the HF/ethanol with water. These results support a quantum confinement mechanism in which exciton migration to traps and nonradiative recombination dominates the de-excitation pathways until silicon nanocrystals are physically separated and energetically decoupled by hydrofluoric acid etching or surface oxidation. The porous silicon surface, as produced by anodization, shows large differences in photoluminescence intensity and peak wavelength over millimeter distances. Parallel Raman measurements implicate nanometer-size silicon particles in the photoluminescence mechanism.
Synthesis of Vanadium Oxide Colloidal Dispersions for Antistatic Coatings
Authors: Morrison Eric.D.
Published: April 2011

Vanadium oxide deposited in thin layers from aqueous colloidal dispersions exhibits electronic conductivity by a small polaron hopping conduction mechanism. Conductivity and static dissipative properties of coatings are unaffected by changes in humidity. Because vanadium oxide is highly colored, the deposition of effective antistatic coatings which are transparent and colorless requires that the percolative (networking forming) properties of the colloidal particles be maximized. The percolative properties of the colloid are strongly influenced by morphology of the dispersed particles and the extent to which they are well dispersed in the aquasol. These properties are determined by the synthetic route to the colloid. Vanadium oxide is the most potent antistatic agent known and has been found to provide antistatic properties even when as little as 1 milligram per square meter is used.
Synthesis of Nanocrystalline Barium-Hexaferrite from Nanocrystalline Goethite Using the Hydrothermal Method: Particle Size Evolution and Magnetic Properties
Authors: Penn R. L. , Banfield J. F. , Voigt J.
Published: April 2011

To characterize particle size/magnetic property relationships, 9 to 50 nm in diameter barium hexaferrite, BaFe12O19 (BHF), particles were prepared using a new synthesis route. By replacing the conventional 50 to 100 nm particles of goethite with nanocrystalline goethite produced via the microwave anneal method of Knight and Sylva [1], nanocrystalline BHF was synthesized using the hydrothermal method. Evolution of particle size and morphology with respect to concentration and heat treatment time is reported. Hysteresis properties, including coercivity (0.2 – 1.0 kOe), magnetization saturation (0.1 – 33.4 emu/g), and magnetization remanence (0.004 – 22.5 emu/g) are discussed as a function of particle size. The magnetization saturation and remanence of the 7 nm particles is nearly zero, suggesting the superparamagnetic threshold size for BHF is around this size. In addition, the equilibrium morphology of BHF crystals was calculated to be truncated hexagonal prisms which was verified by experiment, and the isoelectric point, pH of 4.1, was measured for 18 nm BHF particles.
The Effect of Substrate Type and 2,2′-Bipyridine on the Sorption of Copper(II) on Silica and Alumina
Authors: Cheah Sing-Foong , Brown Gordon E. , Parks George A.
Published: April 2011

We have studied the co-adsorption of Cu(II) and an organic ligand, 2,2′-bipyridine (bipy), on amorphous silica (am-SiO2) and γ-Al2O3 (γ-alumina). This study focuses on two fundamental questions: (1) how bipy affects the macroscopic uptake behavior and molecular-scale characteristics of Cu(II) sorption complexes formed on each oxide; and (2) how and why the uptake behavior and the characteristics of Cu(II) sorption complexes differ for the two oxides. Solution uptake experiments and X-ray Absorption Fine Structure (XAFS) spectroscopy were used to answer these questions.

In the absence of bipy and at a surface loading of approximately 0.05 μM/m2, Cu(II) adsorbs predominantly as a dimeric complex on am-SiO2 surfaces but as a monomeric complex on γ-Al2O3. At low Cu(II) to solid ratio, bipy shifts the pH of Cu(II) sorption on am-SiO2 to lower values, but it shifts the pH of Cu(II) sorption on γ-Al2O3 to higher values. Uptake experiments and XAFS measurements on the wet sorption samples indicate that sorption of aqueous Cu(bipy)2 on γ-Al2O3 displaces one bipy from the aqueous Cu(bipy)2 complex, while sorption on am-SiO2 does not disrupt the complex. More detailed XAFS analysis suggests an innersphere Cu(bipy)1 complex on γ-Al2O3 and a stronger Cu-surface oxygen interaction when Cu(bipy)2 adsorbs on γ-Al2O3 than am-SiO2.
Surface Charge Properties Of Kaolinite
Authors: Schroth B.K. , Sposito G.
Published: April 2011

The surface charge components of two Georgia kaolinites of differing degree of crystallinity (KGa-1 and KGa-2) were measured using procedures based on charge balance concepts. Permanent structural charge density (Σ0) was determined by measuring the surface excess of Cs, which is highly selective to permanent charge sites. The values of Σ0 determined were -6.3 ± 0.1 and -13.6 ± 0.5 mmol kg-1 for kaolinites KGa-l and KGa-2, respectively. The net proton surface charge density (σH) was determined as a function of pH by potentiometric titration in 0.01 mol dm-3 LiC1. Correction from apparent to absolute values of ΣH was made by accounting for Al release during dissolution, background ion adsorption, and charge balance. Lithium and Cl adsorption accounted for the remainder of the surface charge components. Changes in surface charge properties with time were measured after mixing times of 1, 3, and 15 hours (the latter representing “equilibrium”). Time-dependent behavior is believed to be caused by mineral dissolution followed by readsorption or precipitation of Al on the mineral surface. Both the point of zero net charge (p.z.n.c.) and the point of zero net proton charge (p.z.n.p.c.) changed with mixing time, generally increasing. The “equilibrium” p.z.n.c. values were approximately 3.6 and 3.3 for KGa-1 and KGa-2, respectively, while the corresponding p.z.n.p.c. values were about 5.0 and 5.4. The p.z.n.c. results were in good agreement with previous studies, but the values of p.z.n.p.c. were higher than other values reported for specimen kaolinite.
Polarization Relaxation in Pzt/Plzt Thin Film Capacitors
Authors: Jiang Bo , Balu Venkatasubramani , Chen Tung-Sheng , Kuah Shao-Hong , Lee Jack C.
Published: April 2011

Polarization relaxation in PZT and PLZT (with La concentration from 0% to 10%) thin film capacitors was characterized in the time range from 10 ns to 1000 s. It was found that at zero volt the polarization in PZT and PLZT thin films changes logarithmically with time, P(t) = blog(t) + P0, and the polarization current density J(t) = dP(t)/ dt obeys the Curie-von Schweidler Law, J(t) = b. t−x, with n = 1 from 100 ns extending to 10 s. Over 10 s, the exponent n in the J-t relationship becomes less than 1. The coefficient b in the Q-t and J-t relationship at zero volt correlates strongly with the remanent polarization. La doping in PZT reduces remanent polarization and reduces relaxation.
The Phase Diagram of Epitaxial BaTiO3 Films under Bi-Axial Stress
Authors: Desu S. B. , Chen Z. J. , Dudkevich V. P. , Dudkevich P. V. , Zakharchenko I. N. , Kushlyan G. L.
Published: April 2011

The phase diagram of eptaxial BaTiO3 films in the coordinates of T and αs ( substrate thermal expansion coefficient) is constructed on the basis of the thermodynamic analysis which has been carried out earlier [1]. It is found that two new phase are formed under bi-axial stress. The temperature dependencies of polarization and unit cell parameters for the films on the KTaO3 and SrTiO3 substrates are also calculated.
Thin Films of (Ba, Sr)TiO3 by Aerosol Combustion
Authors: Kussmaul A. , Greenwald A.C. , Wei C.H. , Morse T.F.
Published: April 2011

Barium-strontium-titanate (BST) films were deposited on platinum-coated ceramic substrates and platinum foil by the aerosol combustion process. A fine mist of metallic precursors in solution was carried into a methane-oxygen flame to produce ceramic particles, which coated the substrate. Both aqueous and purely organic solutions were tested, the latter producing finer powders (less than 100 nm) with high phase purity. Sintering the as-deposited particulate material led to a porous film at all sintering temperatures studied, regardless of the solution used. Cold pressing of the organicsolution- based material prior to heating, without the addition of any binders or solvents, gave a fully dense solid after sintering at 1450°C.
Epitaxial KnbO3 and Fe-Doped KnbO3 Thin Films Prepared by the Sol-Gel Technique
Authors: Xu Yuhuan , Cheng Chih-Hsing , Mackenzie John D.
Published: April 2011

A mixed alkoxide liquid precursor was used to form epitaxial ferroelectric potassium niobate, KNbO3, thin films through the sol-gel technique by carefully designing the solution chemistry and reaction processes. The double alkoxide solution was prepared through hydrolysis and condensation reactions between different metal alkoxides in solution. Fabrication of heteroepitaxial single crystal thin films of KNbO3 deposited on single crystal substrates of MgO and SrTiO3 will be described. Film structure was investigated with X-ray and electron diffraction, and transmission electron microscopy. Second harmonic generation of 1064 nm incident light was demonstrated for KNbO3 thin films in a waveguide configuration. Transient photorefractive gratings in Fe-doped KNbO3 were studied by a two-beam coupling technique for various writing intensities and wavelengths.
Characterization of Pzt Films by Scanning Force Microscopy (SFM)
Authors: Zavala Genaro , Trolier-McKinstry Susan E. , Fendler Janos H.
Published: April 2011

Scanning Force Microscopy (SFM) has been used for the determination of friction, phase transformation, piezoelectric behavior (contact mode), polarization state and dielectric constant (non contact mode) in several nanometer regions of Lead Zirconate Titanate (PZT) films. The use of the SFM tip, in the contact mode, to polarize different nanoregions of the film and to apply an oscillating field thereon, led to effective piezoelectric coefficients and piezoelectric loops. In the non-contact mode, application of an ac signal (frequency ω) to the tip-electrode system produced an oscillation of the tip at ω (fundamental or first harmonic) and 2ω (second harmonic). The signals ω and 2ω were related to the state of polarization and the dielectric constant of the film. Analysis of the combined contact, non-contact and friction force microscopic data have provided considerable insight into the piezoelectricity and polarization in the nanodomains.
Microstructural Control of RuO2 Electrode and the Related Properties of (Ba, Sr)TiO3 Thin Films
Authors: Choi D.K. , Choi J.Y. , Won J.H. , Paek S.H.
Published: April 2011

Effect of microstructure and surface roughness of oxide electrode on the properties of BST films has been investigated. (Ba, Sr)TiO3 and RuO2 films were deposited by RF magnetron sputtering technique. Surface morphology of RuO2 films were controlled by changing the O2/Ar ratio during deposition. It is found that the grain size and surface roughness of BST films are strongly influenced by RuO2 electrode underneath. When the grain size of RuO2 decreased by reducing either O2/Ar ratio during sputtering or film thickness, BST film resulted in fine grain structure and the leakage current decreased due to the improvement in uniformity of the film. Dielectric constant of BST films, however, was decided from both degree of well defined grains and film continuity related to grain size and surface roughness.
Structural Stability of Si-O-a-C:H/Si-a-C:H Layered Systems
Authors: Müller U. , Hauert R.
Published: April 2011

Amorphous hydrogenated carbon films are of technological interest as protection coatings due to their special properties such as high hardness, chemical inertness, electrical insulation and infrared transparency. However, some applications still suffer from the poor thermal stability and adhesion problems of these coatings. To ensure good adhesion, especially on hardened steels and non-carbide forming substrates, an extra interlayer has to be deposited first. Often a silicon containing interlayer, Si-a-C:H for example, is used for this purpose. This Si-a-C:H interface layer was deposited by rf plasma deposition from tetramethylsilane. Then a-C:H films containing Si-O with a varying silicon content were produced from a mixture of acetylene and hexamethyldisiloxane. The structural changes upon annealing of these films were investigated using Raman spectroscopy. The analysis of the development of the different peaks upon annealing temperature reveals the transition from the amorphous structure to the more graphitic-like structure. This transition temperature increases by as much as 100°C when silicon is incorporated into the DLC film. However, when Si-O is incorporated instead of only silicon the same increase in temperature stability is observed.
Mechanical Behavior of a Ni/TiC Microlaminate Under Static and Fatigue Loading
Authors: Her Y. C. , Wang P. C. , Yang J.-M. , Bunshah R. F.
Published: April 2011

The mechanical behavior and damage mechanisms of the Ni/TiC microlaminate composites under static and cyclic loading were investigated. The relationship between the ultimate tensile strength and the layer thickness at both room temperature and 600°C was studied. The fatigue life and the evolution of the stiffness reduction under various maximum applied stress levels were determined. The results revealed that the ultimate tensile strength linearly increased as the laminate layer thickness decreased. Also, the microlaminate exhibited a non-progressive fatigue behavior.
Fatigue Behavior of Scs-6/Titanium/Titan1ium Aluminide Hybrid Laminated Composite
Authors: Wang P. C. , Her Y. C. , Yang J. -M.
Published: April 2011

The fatigue behavior of the SCS-6 silicon carbide fiber-reinforced Ti-6Al-4V/Ti-25Al- 10Nb hybrid laminated composite was investigated at room temperature. The accumulation of fatigue damage in the form of matrix cracking was measured as a function of loading cycles and applied stress levels. The residual stiffness and residual tensile strength of the post-fatigued specimens were determined. The comparison of the crack growth behavior of the hybrid composite with both the SCS-6/Ti-6-4 and SCS-6/Ti-25-10 composites will also be discussed.
Microscratch Analysis of The Adhesion Failure on Oxide Thin Films With Different Thickness
Authors: Ottermann C. R. , Bange K. , Braband A. , Haefke H. , Gutmannsbauer W.
Published: April 2011

Adhesion failures of Ti2and Ta2O5thin films deposited by reactive evaporation (RE), reactive ion plating (IP) and plasma impulse chemical vapour deposition (PICVD) on fused silica, AF 45, TEMPAX and soda-lime glass substrates are investigated by means of a micro-scratch tester. The oxide films possess thickness between 60 and 500 nm and show different mass densities depending on the deposition conditions. Scratch testing exhibits well pronounced detachment for thicker films on hard substrates. The clearance of the scratch signal is reduced with decreasing layer thickness or for softer substrate materials. The test results are also influenced by the various substrates and different chemical and mechanical properties of the films due to the alternate deposition techniques.
Peel Strength in the Cu/Cr/Polyimide System
Authors: Park I. S. , Yu Jin , Park Y. B.
Published: April 2011

In order to understand the effects of plastic deformation and the interfacial fracture energy on the peel strength, thickness of the metal layer and the pretreatment conditions of polyimide were varied in the Cu/Cr/polyimide system. The work expenditure during the peel test was estimated using the stress strain curves of metal films, X-ray measurements of the plastic strain in the peeled films, and the elastoplastic beam analysis. Results indicate that the peel strength is strongly affected by the film thickness and the pretreatment condition in a synergistic way, and that the measured peel strength is more a measure of the plastic deformation during the peel test than a measure of the true interfacial energy.
The Effect of Ta and N Content on Mechanical Properties of DC Magnetron Sputtered fen and Fetan thin films
Authors: Deng Hong , Minor M. Kevin , Barnard John A.
Published: April 2011

This paper reports nanoindentation studies of the effect of Ta and N content on the mechanical properties of magnetically soft high moment FeN and FeTaN thin films prepared by dc magnetron sputtering. The FeTaN films were deposited on oxidized silicon (100) substrates with a series of FeTa targets in which the Ta content varies from 0 to 25wt%. The hardness (H) and Young's modulus (E) were measured by the Nano Indenter at nine indenter penetration depths: 20, 30, 40, 50, 60, 80, 100, 120 and 200 nm. The inherent hardness values of these films (no substrate effect) can be determined at penetration depths ranging from 20 to 60 nm for the 500 nm thick film used in the study. It was found that for the films deposited from the pure Fe target when the nitrogen flow rate increases from 0 to about 0.5 sccm the hardness of the film increases. However, a decreasing trend in hardness of these films was observed on further increasing the nitrogen flow rate. On the other hand, for the films prepared from the targets with the Ta content in the range of 5–15wt%, the hardness increases whenever Ta and N contents increase. These effects are clearly illustrated by 3-D and contour hardness and Young's modulus maps in this paper.
Microstructure and Mechanical Properties of Thin Al-Si-Ge Films
Authors: Kirchner S. , Kraft O. , Baker S. P. , Arzt E.
Published: April 2011

The mechanical properties are thought to play an important role in the performance of metallization materials for very large scale integration (VLSI) applications. From recent investigations on bulk materials it is known that Al-Si-Ge alloys can be very efficiently strengthened with only a small amount of the alloying elements. These alloys are potential candidates for future metallizations both because Si and Ge are compatible with the existing semiconductor technology, and because the resistivity is expected to be low.

We present the first results of detailed characterizations of Al-Si-Ge thin films as a function of sputter conditions and heat treatments. The microstructure was characterized using x-ray diffraction and transmission electron microscopy. The kinetics of precipitation were studied using resistance measurements. Room temperature hardness was investigated using nanoindentation, and the mechanical properties at temperatures up to 240°C were examined using a substrate curvature method. The correlation between precipitate structure and film properties is discussed.
Adhesion Study of Dlc/Cr/Dlc and Dlc/Ti/Dlc Sandwich Structures on Hardened Steel
Authors: Müller U. , Hauert R.
Published: April 2011

Hard amorphous hydrogenated carbon, also referred to as diamond-like carbon films, are of technological interest as protection coatings due to their special properties such as high hardness, low friction, low wear, chemical inertness and electrical insulation. In this paper a study of the adhesion properties of multilayer structures composed of DLC/Metal/DLC/substrate is presented. As substrates a ball and roller bearing steel (DIN 1.3505, AISI 52100) was used. After Ar plasma cleaning of the substrate, DLC films were deposited from acetylene gas by rf plasma chemical vapor deposition at a self-bias of -600V. Metal films were deposited in the same chamber by DC magnetron sputtering.

Adhesion of the different layers on the underlying layer was investigated by optical analysis of the coating at the border of Rockwell C indentations made into the substrate. If necessary, additional thin layers are deposited at the particular interface to ensure good adhesion. Further information on the interface quality and hence the adhesion is gained by a second optical analysis of the Rockwell indentation after exposure to ambient air for two weeks.

The multilayer structure containing titanium as the metal layer showed no ablation of the coating around the indentation even after two weeks of exposure to ambient air. Chromium on the other hand already showed some ablation immediately after the indentation as well as still ongoing ablation after two weeks. These results are further corroborated by pin-on-disc tests.
Thermal- and Electromigration- Induced Stresses in Passivated AL- and Alsicu-Interconnects
Authors: Beckers D. , Schroeder H. , Eppler I. , Schilling W.
Published: April 2011

Al and Al- alloys are commonly used as interconnect materials in integrated electronic devices. Stress induced voiding and degradation of metal lines by electromigration are closely related to the stresses in the lines.

We have studied the strain and stress evolution during thermal cycling, isothermal relaxation and due to electromigration in passivated Al and AlSi(l%)Cu(0.5%) lines by X-Ray diffraction with variation of experimental parameters such as the aspect ratio and the electrical current density. Furthermore the extent of voiding and plastic shear deformation has been determined from the experimental metal strains with the help of finite element calculations.

Main results are: 1) During thermal cycling the voiding is less than 2 ·10−3. The extent of plastic shear deformation increases with increasing line width and with decreasing flowstress. 2) During isothermal relaxation void growth occurs but no significant change in the plastic shear deformation. 3) An electric current in the lines causes no measurable additional change of the volume averaged stresses up to line failure.
Characterization of Sic Fibers by Soft X-Ray Photoelectron and Photoabsorption Spectroscopies and Scanning Auger Microscopy
Authors: Ma Qing , Mcdowell M. W. , Rosenberg R. A.
Published: April 2011

Synchrotron radiation soft x-ray photoelectron and photoabsorption spectroscopy was used to characterize commercially obtained SiC fibers, which were produced by chemical vapor deposition (CVD) of SiC on a W core, followed by a carbon passivating layer. Depth profiling of the fiber through the carbon/SiC interface was done by making Si 2p and C ls core level PES and PAS, as well as scanning Auger microscopy, measurements following Ar+ sputtering. No significant changes in either photoemission or absorption or Auger line shapes were observed as a function of the depth, which indicates that there is no significant interfacial reaction. The line shapes of the carbonaceous coatings are predominately graphite-like and those of the CVD SiC coatings are microcrystalline, with presence of disorder to some extent in both cases.
Fermi Surface Mapping Using A Third Generation Light Source
Authors: Rotenberg Eli , Denlinger J. D. , Kevan S. D. , Goodman K. W. , Tobin J. G. , Mankey G. J. , Subramanian K.
Published: April 2011

The electronic states at the Fermi surface determine diverse properties such as magnetism, chemical bonding, and phonon-electron coupling. Using a conventional hemispherical analyzer at the ultraESCA beamline 7.0 of the Advanced Light Source, we have measured Fermi contours of the bulk and surface states of Cu(001) and Ag(001). For bulk states, we used uniform sampling in k-space by varying both the electron takeoff angle as well as the photon energy. Three-dimensional plots (in k-space) of bulk and surface states at the Fermi level can easily be achieved within one or two synchrotron shifts. Surface states, whose momentum is independent of k-perpendicular, are easily mapped if sufficiently dense angular sampling is performed. The states crossing the Fermi level at X in the surface Brillouin Zone of Cu(100) and Ag(100) are presented as examples.
A Study on the Metal Induced Lateral Crystallization Behavior of Amorphous Silicon Thin Films
Authors: Lee Byung-Il , Kim Kwang-Ho , Jeong Won-Cheol , Ahn Pyung-Su , Shin Jin-Wook , Joo Seung-Ki
Published: April 2011

Basic mechanisms for both Ni- and Pd-metal induced lateral crystallization (MILC) are investigated. For both cases, tiny silicides were formed under the metal deposited area, and propagated toward amorphous Si films leaving crystallized Si behind at temperatures as low as 500 °C. Ni-MILC was influenced by Pd such that the lateral crystallization rate was enhanced, and the temperature for the lateral crystallization was lowered to 450 °C. Through TEM analysis and external stress experiments, it was found that the enhancement of the lateral crystallization rate was closely related to the compressive stress generated by the formation of nearby Pd2Si.
Effects of Reactive Gas Compositions on the Magnetic Properties and Microstructures of FeTaNC Films
Authors: Koh Tae-Hyuk , Shin Dong-Hoon , Choi Woon , Ahn Dong-Hoon , Nam Seoung-Eui , Kim Hyoung-June
Published: April 2011

Soft magnetic properties and microstructure evolutions of FeTaNC films were investigated, and compared with those of FeTaN and FeTaC films. Effects of substrate species (glass vs. CaTiO3) on the magnetic properties were also investigated. Co-addition of N and C enhances the grain refinements and soft magnetism compared with N or C only addition. Good soft magnetic characteristics of coercivity of 0.17 Oe, permeability of 4000 (5 MHz), and magnetic flux density of 17 kG can be obtained in the FeTaNC films with the relatively wide process ranges. While these values appear to be similar to those of FeTaN films on glass substrate, the most distinctive difference between FeTaNC and FeTaN (or C) films is the effects of substrate. Whereas FeTaNC films show good magnetic characteristics on both glass and CaTiO3 substrates, FeTaN (or C) films show substantial degradation on the CaTiO3 substrate.
The Effect of Growth Temperature on Atomic Ordering in Gao.5 2Ino.48P Epilayers Grown on GaAs (001) Substrates by GS-MBE
Authors: Meenakarn C. , Staton-Bevan A. E. , Dawson M. D. , Duggan G. , Kean A. H. , Najda S. P.
Published: April 2011

A Transmission Electron Microscopy (TEM), Photoluminescence (PL) and Photoluminescence Excitation Spectroscopy (PLE) investigation has been conducted on Ga0 52In0.48P epilayers, grown on GaAs(001) by Gas-Source Molecular Beam Epitaxy. Selected area diffraction in the TEM shows that epilayers grown at temperatures between 480°C and 535°C exhibit CuPt-type ordering with the antiphase domain size increasing with increasing growth temperature. PLE data shows that, in the temperature range 480°C to 535°C the band gap energy of Ga0.52In0-48P epilayers increases with increasing growth temperature from 1.971 to 2.003 (±0.001 eV). For high band gap optical data storage applications these values compare well with the highest band gap energies reported for epilayers grown by MOCVD.
TiSi2 Phase Transformation by Amorphization Techniques
Authors: Karlin Tord , Samuelsson Martin , Nygren Stefan , östling Mikael
Published: April 2011

ULSI packing density calls for sub-micron line widths, but on n-type polysilicon this can lead to incomplete titanium silicide C49 to C54 phase transformation after a conventional two step rapid thermal anneal (RTA). This study compares three different ion beam amorphization techniques: preamorphization, ion beam mixing and silicide amorphization, aiming at a complete phase transformation for submicron silicide lines. For preamorphization, an arsenic implantation at moderate energies (35–75 keV) was used to amorphize the top layer of the polysilicon prior to the titanium deposition. Ion beam mixing used a high-energy (200 keV) arsenic implantation after the titanium deposition to create an amorphous mix of silicon and titanium. These two methods did, each by themselves, lead to an increased fraction of C54 silicide grains already during the low temperature RTA, and a complete phase transformation during the subsequent high temperature RTA. Both methods lowered the thickness difference between titanium silicide on p- and n-type silicon. Silicide amorphization with 75 keV arsenic or 100 keV antimony, applied before the second RTA, did not significantly improve the silicide phase transformation.
Doping properties of the Ion-Beam-Sputtered SiGe Film
Authors: Qi Wen-Jie , Wang Zhi-Sheng , Gu Zhi-Guang , Ru Guo-Ping , Jialig Guo-Bao , Li Bing-Zong
Published: April 2011

The ion-beam-sputtered polycrystalline SiGe film and its doping properties have been studied. Boron and phosphorus have been doped into the sputtered poly-SiGe film by ion implantation and diffusion. To activate the implanted impurities, both rapid thermal annealing and fiirnace annealing have been used. The electrical measurements show that boron and plhosphorus can be doped into sputtered SiGe films and effectively activated by both ion implantation with post-annealing and diffiision. Hall mobilities as high as 31 cm2/V-s and 20 cm2/V.s have been obtained in B-difflhsed and P-diffused SiGe films, respectively. The x-ray diffraction spectra of the sputtered Sifie filhn show its typical polycrystalline structure with (111), (220) and (311) as the preferential orientations.
Atomic Force Microscopy Investigation of the Morphology of A UV Photodefined Palladium Activation Layer on Alumina Ceramic and the Nucleation of Electroless Copper at the Activated Sites
Authors: Lafferty E. J. , Macauley D. J. , Kelly P. V. , Crean G. M.
Published: April 2011

The surface morphology of a UV excimer lamp photodefimed palladium activation layer and its effect on subsequent electroless copper deposition have been studied on 96% alumina substrates using an atomic force microscope (AFM). The morphology of the activation layer and the density of the palladium catalyst are important factors affecting the initial stages of the electroless deposition and the microstructure of the copper film. Under activation conditions on which a subsequent electroless copper deposit exhibited good adhesion characteristics, the palladium activation was found to have a nodular structure with a large distribution of palladium particle sizes of the order of 10 nm at grain boundaries and the edges of grain steps, with smaller activation particles observed on smoother areas of the alumina grains. The influence of substrate morphology on the nature of the catalytic sites and thence, on the nature of the subsequently deposited metal was investigated, both at the nucleation stage, and as the autocatalytic electroless deposition reaction proceeded. The recrystallisation of the initial electroless deposit, the morphology of the resulting copper films and its relationship to catalyst particle size are reported. The principal determining factors in the substrate and activation layer morphology which control the microstructure of the electroless copper deposit are discussed.
Characterization of Platinum films Deposited by a Two-Step Magnetron Sputtering on SiO2/Si Substrates
Authors: Lee Dong-Su , Park Dong-Yeon , Kim Min Hong , Chun Dong-Il , Ha Jowoong , Yoon Euijoon
Published: April 2011

In this study, defect-free Pt films with good adhesion were deposited on SiO2/Si substrates by a two-step magnetron sputtering. This method consists of the first sputtering step using Ar/O2 gas mixture and the second step using Ar. After two-step deposition, an annealing process was followed at 600-1,000 °C in ambient atmosphere. In the first step, oxygen containing Pt films were deposited. Oxygen incorporated in the Pt films completely diffused out during the high temperature annealing. After the annealing process, the film became dense without catastrophic failures such as hillock, pinhole or buckling. Adhesion strength of films produced by this process was good enough to pass a tape test. It is believed that the good adhesion and the observed microstructural evolution are related to the oxygen in Pt films introduced during the first sputtering step. Adhesion, microstructural evolution and the role of oxygen in Pt films are briefly discussed.
Formation and Phase Transformation of R. F. Sputter Deposited NON-BCC 6-A15 Chromium Thin Films
Authors: Chu J. P. , Chang J. W. , Lee P. Y. , Wu J. K.
Published: April 2011

Formation and phase transformation of non-BCC δ-A15 Cr thin films prepared by R. F. magnetron sputtering have been characterized. Processing parameters such as working pressure, deposition time and temperature were found to affect the formation of δ-A15 Cr films. Using differential scanning calorimetry, we have demonstrated for the first time that the phase transformation of the δ-A15 Cr phase to the equilibrium c-BCC Cr phase is an irreversible, exothermic, first-order transition. At a heating rate of 10°C/min, the onset and peak temperatures of transformation were determined to be 428°C and 437°C, respectively. Our post-deposition annealing study by X-ray diffraction further verified the occurrence of transformation.
Epitaxial Batio3 and Knbo3 Thin Films On Various Substrates for Optical Waveguide Applications
Authors: Beckers L. , Zander W. , Schubert J. , Leinenbach P. , Buchal Ch. , Fluck D. , Gügnter P.
Published: April 2011

Technologically interesting optical materials such as BaTiO3 and KnbO3 are difficult to grow as single crystals of large dimensions. Thin film techniques can overcome this problem by synthesizing these materials on commercially available substrates. We demonstrate the deposition of single crystalline BaTiO3 and KnbO3 on MgO, SrTiO3 and buffered MgO substrates by Pulsed Laser Deposition (PLD). The samples are characterized by Rutherford Backscattering Spectrometry / Channeling (RBS/C), X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM). We found excellent crystalline quality, confirmed by RBS/C minimum yield values of 2 % and a FWHM of 0.36° of the BaTiO3(002) rocking curve. Even films of a few microns thickness have been grown without loss of crystalline perfection, and all films show very flat surfaces. The RMS roughness of a 950 nm BaTiO3 film was found to be 1.1 nm.