bluuebunny/crossref_metadata_2025 huggingface dataset:
Ballistic-Electron-Emission Microscopy (BEEM) Studies of Gainp/GaAs Heterostructures
Authors: O'Shea J. J. , Reaves C. M. , Chin M. A. , Denbaars S. P. , Gossard A. C. , Narayanamurti V. , Jones E. D.
Published: April 2011

Ballistic-electron-emission microscopy (BEEM) has been used to study band-offsets in n-and p-type GaInP/GaAs heterostructures. We determine room temperature offsets of 30 meV and 350 meV in the conduction and valence bands, respectively, for thin GaInP layers grown by metal-organic chemical vapor deposition (MOCVD) at 610°C. Low temperature (77 K) measurements also indicate at least 90% of the band discontinuity lies in the valence band for these ordered GaInP samples.
Electromigration Failure Distributions for Multi-Layer Interconnects as a Function of Line Width: Experiments and Simulation
Authors: Brown D. D. , Sanchez J. E. , Pham V. , Besser P. R. , Korhonen M. A. , Li C.-Y.
Published: April 2011

In narrow metal lines used for chip level interconnects, the line width can strongly affect the electromigration reliability, typically due to variations in the microstructure and in the mechanical stress state. These variations have a stronger effect as the line width decreases to the order of the metal grain size or less. Electromigration failure distributions were obtained both experimentally and by simulation for realistic interconnect structures with six different line widths, ranging from lμm to 8μm. In order to simulate the electromigration failure distributions, microstructure statistics were obtained (using TEM) and the critical void volume for failure was measured (using SEM) for each line width. The simulated failure times match the experimental failure times for narrow line widths (1-4μm).
Modelling Geometrical Effects of Parasitic and Contact Resistance of FET Devices
Authors: Reeves Geoffrey K. , Harrison H. Barry , Leech Patrick W.
Published: April 2011

The continual trend in decreasing the dimensions of semiconductor devices results in a number of technological problems. One of the more significant of these is the increase in contact resistance, Rc. In order to understand and counteract this increase, Rc needs to be quantitatively modelled as a function of the geometrical and material properties of the contact. However the use of multiple semiconductor layers for ohmic contacts makes the modelling and calculation of Rc a more difficult problem. In this paper, a Tri-Layer Transmission Line Model (TLTLM) is used to analyse a MOSFET ohmic contact and gatedrain region. A quantitative assessment of the influence on Rc of important contact parameters such as the metal-silicide specific contact resistance, the silicide-silicon specific contact resistance and the gate-drain length can thus be made. The paper further describes some of the problems that may be encountered in defining Rc when the dimensions of certain types of contact found in planar devices decrease.
High quality GdSil.7 layers formed by high dose channeled implantation
Authors: Wu M. F. , Vantomme A. , Pattyn H. , Langouche G. , Bender H.
Published: April 2011

Thin gadolinium silicide layers have been formed by channeled ion beam synthesis. Continuous and heteroepitaxial GdSil.7 layers with a hexagonal structure and a χmin value of 10% are prepared by Gd ion implantation at 90 keV to a dose of 1.3x1017/cm2 at 450°C in Si(111) using channeled implantation. The hexagonal phase of GdSi1.7 is stable up to a temperature of 850°C. Both the crystalline quality and the phase stability are much better than the results obtained by conventional techniques. Annealing at > 900°C suddenly changes the χmin value of the silicide layer from 10% to 100%. X-ray diffraction shows that the phase has changed to orthorhombic. RBS/channeling, x-ray diffraction and transmission electron microscopy are used in this study.
NMR Studies of Hydrofluorocarbon-Cation Interactions and Cation Migrations on Adsorption of Hydrofluorocarbon-134 on Zeolites NaY and CsY
Authors: Grey Clare P. , Poshni Faiza I. , Ba Yong , Corbin David R.
Published: April 2011

23Na and 23Na/19F double resonance MAS NMR methods have been used to study the binding of hydrofluorocarbon-134 (CF2HCF2H) in zeolites NaY and CsY. The interaction of HFC- 134 with the sodium cations is so strong that the sodium cations in the sodalite cages (site I') migrate into the supercages to bind to the hydrofluorocarbon molecules.
Effect of Processing Variables on the Microstructure and Mechanical Properties of Microporous Carbon Materials
Authors: Singh M. , Dacek R. F.
Published: April 2011

Microporous carbon materials with different pore and strut sizes have been fabricated by the pyrolysis of furfuryl alcohol resin, triethylene glycol, and p-toluene sulfonic acid mixtures. The resulting materials were characterized by scanning electron microscopy and density measurements. The room temperature flexural strength and modulus of these materials decreases with increasing amount of acid curing agent.
From Graphite to Porous Carbon Containing Nanoparticles through Chemical Reactions
Authors: Hung C. C. , Corbin J.
Published: April 2011

Porous carbon containing large quantities of separated individual nanoparticles (2–100 nm) was produced. The chemical process includes fluorination or oxygenation of graphite, and then exposing the product (graphite fluoride or graphite oxide) to metal chlorides. The nanoparticles were metal halides or metal oxides, which could contain dopants if they were added during the synthesis process. The metal to carbon atomic ratio was in the range of 1 (3–6). The chlorides used in this research include those of Pd, Zn, Al and Li. Depending on the synthesis process, the carbon pores could be either filled with the nanoparticles, resulting in near-zero surface area and high metal concentration, or partially filled with nanoparticles, resulting in large surface areas. In this report, near zero surface areas were observed for a product of LiCl in carbon, and a surface area of 75 m2/g was observed for the product of γ- Al2O3 in carbon. Heating these products in 1 atm air allowed the nanoparticles to become fuse together in the form of metal oxide while the carbon was oxidized, producing metal oxides which have the same shape as the carbon precursors (fibers, fabrics, or powder) and large surface areas. These products are potentially useful in the area of batteries, high temperature gas sensors, and catalysts. Also, these products could be used to examine individual nanopartidles, whose electrical, optical, and chemical properties differ from those of their single crystal or amorphous counterparts
Improving Thermal Performance of High Internal Phase Emulsion Polymerized Foams with Maleimide Based Monomers
Authors: Hoisington Mark A. , Duke Joseph R. , Langlois David A.
Published: April 2011

The influence of three N-substituted maleimides on the thermal performance of high internal phase emulsion (HIPE) polymerized foams were investigated. N-propylmaleimide, Nbutylmaleimide, and N-cyclohexylmaleimide were copolymerized with styrene and crosslinked with either divinylbenzene or Bis(3-ethyl-5-methyl-4-maleimide-phenyl)methane in a HIPE polymerization process. All maleimide modifiers produced increases in the foam glass transition temperature (Tg) as a function of the maleimide concentration. The degree of Tg improvement was strongly dependent on the N-substituted maleimide used during processing.
Precipitation of Iron(III) Hydroxides from Homogeneous Solutions
Authors: Deng Yiwei
Published: April 2011

The technique of precipitation from homogeneous solutions was used in this study to simulate the formation of iron(III) hydroxides under conditions similar to those at the redox boundary in natural waters. The technique allowed the precipitation of iron(III) hydroxides to occur when the precipitant iron(III) was slowly generated by the oxygenation of iron(II) and subsequently hydrolyzed. During the precipitation, no pH heterogeneity occurred locally as it was usually observed in the conventional preparation of iron(III) hydroxides in the laboratory. Thus, the rapid hydrolysis of ferric ions and the subsequent polymerization of iron(III) hydroxides were effectively prevented. The iron(III) precipitates formed in this way are more representative of the iron(III) particles occurring at the redox boundary in natural waters than those formed by the conventional procedure in the laboratory. The effect of solutes (e.g., H4SiO4) on the structure, size and shape of the iron(llI) hydroxides formed has also be studied.
The Effect of Hydrophobicity of Silicate Minerals on the Adsorption of Dodecylammonium Acetate
Authors: Huang Picheng , Fuerstenau Douglas W.
Published: April 2011

The interaction between hydrophobic species plays an important role in the adsorption of surfactants. In this paper, naturally hydrophilic quartz and naturally hydrophobic talc were selected as model minerals for studying the adsorption of the cationic surfactant, dodecylammonium acetate (DAA). The effect of the hydrophobicity of minerals on the adsorption of DAA was investigated by measuring zeta potentials, adsorption densities and suspension stabilities as a function of pH in the presence of DAA.
The Solubility of Some Alkali-Bearing Zr Minerals in Hydrothermal Solutions
Authors: Aja S. U. , Wood S. A. , Williams-Jones A. E.
Published: April 2011

The hydrolytic dissolution of some Zr-bearing minerals has been measured in aqueous KCl and KF solutions. Depending on the mineral being investigated, Zr concentrations varied from about 9 ppb to nearly 40 ppm in equilibrated solutions; this validates the notion of Zr mobility in some crustal fluids. At 50 °C, ΔfG were determined (using the measured solubility products) for Na catapleiite, elpidite, vlasovite and weloganite to be -4654.2±5.6, -7391.0±11.6, -5181.0±7.3 and -7130.5±1.0 kJ/mol, respectively. Calculated phase relationships amongst the zirconosilicates found at the Strange Lake peralkaline complex indicate that elpidite and gittinsite cannot coexist stably implying a two-stage hydrothermal mineralization process.
Leakage Currents in CVD (Ba,Sr)TiO3 Thin Films
Authors: Basceri C. , Streiffer S.K. , Kingon A.I. , Bilodeau S. , Carl R. , Buskirk P.C. Van , Summerfelt S.R. , Mcintyre P. , Waser R.
Published: April 2011

We have analyzed the leakage behavior of polycrystalline MOCVD (Ba,Sr)TiO3 thin films as a function of both temperature and field. Of the possible mechanisms, thermionic (Schottky) emission gives a self-consistent description of the temperature and field dependencies of the true leakage current for fields in the range of 240–970 kV/cm, and yields realistic barrier heights of 1.2 eV for Pt as the cathode material. For film thicknesses of interest for use in DRAMs, the capacitance-voltage characteristics are explained via Landau-Ginzburg-Devonshire theory. Preliminary resistance degradation studies are also discussed.
In Situ Investigation of Crystallization Kinetics in Pzt Films by Light Scattering
Authors: Shur V.YA. , Negashev S.A. , Subbotin A.L. , Borisova E.A. , Trolier-Mckinstry S.
Published: April 2011

This paper presents the in situ investigation of the crystallite evolution/growth during annealing of amorphous sol-gel Pb(Zr,Ti)O3 thin films by elastic light scattering. XRD and SEM measurements of partly crystallized films of crystallite evolution were used for verifying the method.
Growth of Metal Alkoxide Solution Derived Epitaxial LiNbO3 Thin Films for Optical Waveguides
Authors: Nashimoto Keiichi , Nakamura Shigetoshi , Moriyama Hiroaki
Published: April 2011

Solid phase epitaxial growth of LiNbO3 thin films, using a methoxyethoxide solution process, has been examined for optical waveguide applications. The growth variables such as crystallization temperature, crystallization time, and film thickness have been found to be critical factors in the quality of LiNbO3 thin films. High quality epitaxial LiNbO3 films were grown on sapphire (001) substrates using optimized buffer layers. The LiNbO3 showed single orientation, rocking curve full width at half maximum less than 0.04°, and rms roughness of 2.3 nm, in addition to refractive index of 2.24 and optical propagation loss of 3.0 dB/cm.
The Investigations of Dielectric Properties of BaTiO3 Thin Films on Polycrystalline Pt Substrates by Rf Magnetron Sputtering
Authors: Jang Jin Wook , Cho Woon Jo , Hahn Taek Sang , Choi Sang Sam , Chung Su Jin
Published: April 2011

Thickness dependence of ferroelectric and structural properties of BaTiO3 thin films were investigated. Stoichiometric BaTiO3 thin films were prepared by off-axis rf magnetron sputtering on polycrystalline Pt substrates at 700°C. Film thickness range was 2,100–20,000Å. Room temperature permittivity, frequency dependence of permittivity, and D-E hysteresis loops were measured and lattice parameters were determined as a function of the film thickness. It has been found that these properties had the strong dependence on film thickness, which was mainly due to grain sizes of BaTiO3 thin films. The main cause of thickness dependence of dielectric properties was thought to be crystallinity and stresses of thin films which is resulted from changes in grain sizes.
Residual Stress Distribution in an Al2O3-Ni Joint Bonded with a Composite Layer
Authors: Wang X.-L. , Rabin B. H. , Williamson R. L. , Bruck H. A. , Watkins T. R.
Published: April 2011

Neutron diffraction was used to investigate the residual stress distribution in an axisymmetric A12O3-Ni joint bonded with a 40 vol%A12O3-60 vol%Ni composite layer. A series of measurements was taken along the axis of symmetry through the A12O3 and composite layers. It is shown that after taking into account the finite neutron diffraction sampling volume, both the trends and peak values of the experimentally determined strain distribution were in excellent agreement with calculations of a simple finite element model, where the rule-of-mixtures approach was used to describe the constitutive behavior of the composite interlayer. In particular, the predicted steep strain gradient near the interface was confirmed by the experimental data.
Low Temperature Synthesis of MO2C/W2C Superlattices via Ultra-Thin Modulated Reactants
Authors: Johnson Christopher D. , Johnson David C.
Published: April 2011

We report here a synthesis method of preparing carbide superlattices using ultra-thin modulated reactants. Initial investigations into the synthesis of the binary systems, Mo2C and W2C using ultra-thin modulated reactants revealed that both can be formed at relatively low temperature(500 and 600°C respectively). DSC and XRD data suggested a two step reaction pathway involving interdiffusion of the initial modulated reactant followed by crystallization of the final product, if the modulation length is on the order of 10 Å. This information was used to form Mo2C/W2C superlattices using the structure of the ultra-thin modulated reactant to control the final superlattice period. Relatively large superlattice modulations were kinetically trapped by having several repeat units of each binary within the total repeat of the initial reactant. DSC and XRD data again are consistent with a two step reaction pathway leading to the formation of carbide superlattices.
Pressureless Co-Sintering of Al2O/ZrO2 Multilayers and Bilayers
Authors: Cai Peter Z. , Green David J. , Messing Gary L.
Published: April 2011

Various types of damage were observed in pressureless-sintered Al2O3/ZrO2 symmetric laminates (multilayers) and asymmetric laminates (bilayers) fabricated by tape casting and lamination. These defects included channel defects in ZrO2-containing layers, Al2O3 surface defects parallel to the layers, decohesion between the layers, and transverse damage within the Al2O3 layer in the bilayers. Detailed microscopic observation attributed the defects to a combined effect of mismatch in both sintering rate and thermal expansion coefficient between the layers. Crack-like defects were formed in the early stages of densification, and these defects acted as pre-existing flaws for thermal expansion mismatch cracks. Curling of the bilayers during sintering was monitored and the measured rate of curvature change, along with the layer viscosities obtained by cyclic loading dilatometry, was used to estimate the sintering mismatch stresses. The extent of damage could be reduced or even eliminated by decreasing the difference in layer sintering rate. This was accomplished by reducing the heating rates or by adding Al2O3 in the ZrO2 layers.
Influence of Cu Deposition Conditions on The Microstructure and Adhesion of Cu/Cr Thin Film To Polyimide Film
Authors: Joh Cheol-Ho , Kim Young-Ho
Published: April 2011

Abstracts

The microstructure of Cu thin films in various deposition conditions and the influence of their microstructure on the adhesion strength between Cu/Cr films and polyimides were studied. Cr films (50 nm thick) and Cu films (500 or 1000 nm thick) were deposited on polyimide films by DC magnetron sputtering. The Ar pressure during Cu deposition was controlled to 5, 50, and 100 mtorr. The microstructure was characterized using SEM and TEM. The adhesion strength between Cu/Cr and polyimide was measured using a modified Tpeel test. Plastic deformation of the peeled metal was qualitatively measured using the XRD technique. The Cu film sputtered at 5 mtorr has a dense and uniform structure, while lowdensity regions or open boundaries between columns exist in the film deposited at higher pressure. As sputtering pressure increases, open boundaries are observed more frequently. The peel adhesion strength of Cr film to polyimide increases with Cu sputtering pressure. The adhesion change of Cu/Cr film can be interpreted as the difference in plastic deformation. Open boundaries in the Cu film seem to play an important role in increasing the amount of plastic deformation in the metal film during peeling.
In Situ Electron Spectroscopic Identification of Carbon Species Deposited by Laser Ablation
Authors: Samano E. C. , Soto Gerardo , Gamietea Arturo , Cota Leonel
Published: April 2011

Thin carbon films were grown on Si (111) substrates by ablating a graphite target utilizing an excimer pulsed laser in a UHV Riber © LDM-32 system. Two kinds of films were produced, a highly oriented pyrolytic graphite (HOPG) type and a diamond-like carbon (DLC) type. A relationship of the films microstructure with laser power density and substrate conditions was observed. The HOPG films were homogeneous but the DLC films were heterogeneous, as shown by micrographs. The thin films are monitored and analyzed in situ during the first stages of the deposition process. The monitoring was done by RHEED and the characterization by several surface spectroscopic techniques, AES, XPS and EELS. The formation of a SiC interface was observed for both films due to the reaction of the first carbon species with the substrate surface.
Detection of Similar Elastic Properties Using a Magnetic Force Controlled Afm
Authors: Yamamoto Shin-Ichi , Yamada Hirofumi , Jarvis Suzanne P. , Motomatsu Makoto , Tokumoto Hiroshi
Published: April 2011

We have investigated regional variations of elastic properties using a magnetic force controlled AFM. A piece of small magnet was fixed at the end of the backside of the AFM cantilever so as to apply forces directly to the tip through the external magnetic field of an electromagnet. By modulating the applied forces to the tip and measuring the resulting amplitude of oscillation, a sensitive measurement of the local contact stiffness can be made. We have applied this technique to phase-separated films of polystyrene/polymethylmethacrylate (PS-PMMA) which have almost identical Young's moduli.
Finite Element Modeling of Grain Aspect Ratio and Strain Energy Density in a Textured Copper Thin Film
Authors: Vinci R. P. , Bravman J. C.
Published: April 2011

We have modeled the effects of grain aspect ratio on strain energy density in (100)-oriented grains in a (111)-textured Cu film on a Si substrate. Minimization of surface energy, interface energy, and strain energy density (SED) drives preferential growth of grains of certain crystallographic orientations in thin films. Under conditions in which the SED driving force exceeds the surface- and interface-energy driving forces, Cu films develop abnormally large (100) oriented grains during annealing. In the elastic regime the SED differences between the (100) grains and the film average arise from elastic anisotropy. Previous analyses indicate that several factors (e.g. elimination of grain boundaries during grain growth) may alter the magnitude of the SED driving force. We demonstrate, using finite element modeling of a single columnar (100) grain in a (111) film, that changes in grain aspect ratio can significantly affect the SED driving force. A minimum SED driving force is found for (100) Cu grains with diameters on the order of the film thickness. In the absence of other stagnation mechanisms, such behavior could cause small grains to grow abnormally and then stagnate while large grains continue to grow. This would lead to a bimodal grain size distribution in the (100) grains preferred by the SED minimization.
Mechanical Properties of CuNi Films
Authors: Brückner W. , Macionczyk F. , Reiss G.
Published: April 2011

The mechanical properties of resistive CuNi films sputtered on both silicon wafers and flexible Kapton foils are important for reliability and lifetime of resistors. Studies of stress-temperature dependence and stress relaxation, stress-strain measurements and scanning scratch tests were performed to investigate film stresses, elastic properties, plastic flow, stress for crack initiation and film adhesion. The growth and annealing stresses were found to be tensile and can be seen as the reason for resistance degradation by stress relaxation due to plastic flow. The strains for crack initiation of 0.2 % to 0.7 % depending on film thickness and annealing restrict the application in resistors on flexible substrates. The film adhesion can be improved by a NiCr base-layer.
Indentation Modulus and Hardness in Heteroepitaxial AlxGa1-xP Films
Authors: Roos B. , Santana C. J. , Abernathy C. R. , Jones K. S.
Published: April 2011

AlxGa1-xP layers (0 ≤ x ≤ 0.7), with thicknesses of ≤ 1 μm were grown on Si (100) wafers by metal-organic molecular beam epitaxy (MOMBE) at 450 °C. Transmission electron micrographs of the single crystal films revealed that the microstructure contains stacking faults and microtwins especially near the interface as well as both threading and misfit dislocations. Hardness and elastic modulus were measured using a Nanotest 500 indenter, which can probe the film properties without influence from the substrate.

The hardness H varies linearly according to (11.8 - 2.3x) GPa. The absence of alloy hardening is due to the fact that there is no difference in atomic size of Al and Ga. The indentation modulus E/(1-v 2) decreases monotonically from 136 GPa for GaP to 129 GPa for Al0.7Ga0.3P and bows only slightly (about 2 %) below the straight line of linear interpolation.
Origins of Residual Stress in Mo and Ta Films: the Role of Impurities, Microstructural Evolution, and Phase Transformations
Authors: Parfitt L. J. , Karpenko O. P. , Rek Z. U. , Yalisove S. M. , Bilello J. C.
Published: April 2011

Both the sign and magnitude of residual stress can vary with the thickness of sputter deposited films. The origins of this behavior are not well understood. In this work, we consider the correlation between the residual stress behavior and the depth dependence of impurities in thin (2.5 nm - 150 nm) sputtered Mo and Ta films. We also consider the effects of phase transformations and microstructural changes on the stress behavior. Films were deposited onto Si substrates with native oxide. The residual stress observed in the Mo films varied from highly compressive at 2.5 nm film thickness to ∼ 0 ˜ 10 nm thickness. Ta films also exhibited a high compressive stress, which relaxed from highly compressive to tensile between 10 nm and 50 nm film thickness. Impurities in the films may originate from the sputtering targets, the background gases, and the substrate surfaces. Auger Electron Spectroscopy (AES) results showed the presence of O and C contamination near the film/Si interface; these impurities contributed to the compressive stresses in the thinner films. As anticipated, both Mo and Ta films exhibited grain growth as a function of film thickness, which may have contributed to the relaxation in the compressive stress. The Mo films were entirely bcc. The Ta films showed a transformation from the amorphous phase to the β crystalline phase between 2.5 nm and 20 nm film thickness, which contributed to the relaxation in stress observed in that thickness regime.
Fracture of Thin Tantalum Nitride Films on Ain Substrates
Authors: Moody N. R. , Medlin D. , Norwood D. P.
Published: April 2011

Nanoindentation, continuous nanoscratch testing, and transmission electron microscopy were used in this study to determine the structure-property relationships of thin tantalum nitride resistor films on aluminum nitride substrates. The films were sputter-deposited to a nominal thickness of 200 nm during one production run and then tested at room temperature. Most films were uniform in structure and thickness, consisting of fine equiaxed crystallites along the film-substrate interfaces and long columnar grains further away from the interface. However, one film varied greatly in thickness across the substrate. It had large crystallites along the film-substrate interface and clusters of columnar grains. Most importantly, it contained a far greater amount of porosity than the other films. The high porosity content led to significantly lower elastic moduli and hardness values than the low porosity films and a much greater susceptibility to fracture.
Ordered Structure in Lead Magnoniobate (PMN) by Resonant X-Ray Scattering
Authors: Gosula V. , Chen Haydn , Teslic S. , Egami T. , Vakhrushev S.
Published: April 2011

Half integer superlattice reflections characteristic of ordered structure in PMN (Pb(Mg1,3Nb2,3)O3) single crystal have been measured using resonant synchrotron x-ray scattering near the Pb LIII absorption edge. These superlattice peaks have been previously reported in PMN by electron diffraction, and were interpreted in the context of a two phase Nb/Mg ordering model to explain its relaxor ferroelectric behavior. Nevertheless, the microscopic origin of the superlattice peaks is controversial. Previous results have shown that the Nb atom contributes heavily to the superlattice peaks. However, the effective scattering factor for these peaks is significantly smaller than in the case of complete ordering. In addition, there is strong evidence that lead participates in the ordering.
X-Ray Absorption Fine Structure Applied to the Study of Systems with Lattice Instabilities
Authors: Leon J. MUSTRE DE , Conradson S. D. , Tyson T. , Bishop A. R. , Salkola M. , Espinosa F.J. , Peña J. L.
Published: April 2011

We present a simplified model of electrons and phonons in a three-site cluster as a paradigm of a system exhibiting a lattice instability. We point out the utility of X-ray absorption fine structure (XAFS) in the study of materials where the coupling between electrons and phonons leads to the appearance of such lattice instabilities. As examples of these systems, we present X-ray absorption fine structure (XAFS) measurements on magnetic manganese oxide materials and II-VI semiconductors. Both of these systems exhibit local lattice instabilities which are reflected in the transport properties. In the case of the manganese oxide La0.67Ca0.33MnO3 we observe a change in the Mn-O local structure accompanying the ferromagnetic and metal-insulator transitions. For In doped CdTe we observe the appearance of a lattice distortion centered at the Cd atoms as the In concentration is increased. This distortion is associated with the trapping of free charge carriers, leading to the saturation of the conductivity as the In concentration increases.
Microbeam XAFS Investigations on Fluid Inclusions
Authors: Mayanovic Robert A. , Anderson Alan J. , Bajt Saša
Published: April 2011

In this paper, we discuss the use of x-ray absorption fine structure (XAFS) techniques for the determination of structure of metal complexes in fluid inclusions heated to elevated temperatures. Analysis of Zn K-edge XAFS spectra measured from a single hypersaline fluid inclusion in quartz shows that the ZnCl42- complex is dominant at all temperatures up to and including 430 °C. The Zn-Cl bond length was found to decrease uniformly with temperature, up to nearly 2% at 430 °C in comparison to the value at 25 °C. The Zn-Cl mean-square relative displacement increased linearly with temperature, from a value of 0.0043 Å2 at 25 °C to 0.0089 Å2 at 430 °C.
X-Ray Absorption at Si K-Edge for Novel 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

We present results of Si K-edge XANES-investigations for novel Si-C-N containing solid phases prepared by annealing of Si(NCN)2 at temperatures between room temperature (RT) and 1600°C. The chemical equivalence of the NCN-group arid oxygen as a ligand of silicon is confirmed. The spectra show the presence of an intermediate crystalline phase and its decomposition. Furthermore the recrystallisation of a Si3N4/SiC composite material and its dependence on temperature can be seen.
Complete k-Space Visualization Of X-Ray Photoelectron Diffraction
Authors: Denlinger J. D. , Rotenberg Eli , Kevan S. D. , Tonner B. P.
Published: April 2011

A highly detailed x-ray photoelectron diffraction data set has been acquired for crystalline Cu(001). The data set for bulk Cu 3p emission encompasses a large k-space volume (k=3–10 Å-1) with sufficient energy and angular sampling to monitor the continuous variation of diffraction intensities. The evolution of back-scattered intensity oscillations is visualized by energy and angular slices of this ‘volume’ data set. Large diffractyyion data sets such as this will provide rigorous experimental tests of real-space reconstruction algorithms and multiple-scattering simulations.
Application of Mxcd to Magnetic Thin-Film Sensors
Authors: Bedrossian P. J. , Tobin J. G. , Jankowski A. F. , Waddill G. D. , Anthony T. C. , Brug J. A.
Published: April 2011

While Magnetic X-ray Circular Dichroism (MXCD) has been applied extensively to the extraction of elemental magnetic moments in various magnetic multilayers, the configuration of actual devices imposes certain constraints on the application of MXCD to devices. Using a set of real, thin-film spin valve devices with varying Cu spacer layer thicknesses, we demonstrate the correlation between MXCD and magnetoresistance measurements on those devices as well as the restrictions on the interpretation of MXCD data imposed by both the device topology and the formulation of realistic error estimates.
Generation and Suppression of Stacking Faults in Gap Layers Grown on Si(100) Substrates by Molecular Beam Epitaxy and Migration Enhanced Epitaxy
Authors: Takagi Y. , Yonezu H. , Samonji K. , Tsuji T. , Ohshima N.
Published: April 2011

We have investigated the generation process of crystalline defects in GaP layers grown on Si substrates (GaP/Si) by molecular beam epitaxy (MBE) and migration enhanced epitaxy (MEE). Transmission electron microscopy observations revealed that a regular network of misfit dislocations was generated in GaP/Si by MEE. On the other hand, threading dislocations as well as interfacial misfit dislocations were observed in GaP/Si by MBE. Moreover, stacking faults were generated in high density at the hetero-interface of GaP/Si by MBE. The density of stacking faults was drastically reduced by MEE.
Carrier Transport in Ordered and Disordered In0.53Ga0.47As
Authors: Ahrenkiel R. K. , Ahrenkiel S. P. , Arent D. J. , Olson J. M. , Wanlass M.
Published: April 2011

Ga0.47In0.53As films are grown by metal-organic chemical vapor deposition (MOCVD) on InP substrates and are lattice-matched to the latter. Studies have shown that by varying growth temperature and lattice orientation, some ordering of the metal sublattice is produced. In this work, we studied the excess carrier lifetimes in ordered and disordered films using an ultra-high frequency photoconductive decay measurement technique (UHFPCD). Excitation was provided by a Q-switched YAG laser (1.064 μs wavelength) with pulses of about 5 ns full width half maximum (FWHM). The transient photoconductive decay (PCD) signals varied markedly with the degree of ordering of the specific film. As description of the experimental results of these UHFPCD measurements follow.
MOCVD growth of ZnCdSe on InP (001) substrates
Authors: Won Hon-Kit , Hark S. K.
Published: April 2011

A series of ZnCdSe epitaxial films containing various amounts of Cd were grown on InP (001) substrates using DEZn, DMCd and DESe in the temperature range of 350 to 450°C. The composition and structure of the films were studied by EDX and high resolution X-ray diffraction techniques. It was found that Cd rich films were obtained at low while Zn rich films at high growth temperatures. Double-crystal rocking curves of the films showed that the Cd rich films have substantially fewer defects than similar films grown on GaAs. This improvement in structure is attributed to the closer match of the lattice parameters of lnP and ZnCdSe. The independent determination of composition and structure allowed us to measure the degree of relaxation of the films. We found that even for films whose thickness far exceeds the critical thickness, complete relaxation is not achieved.
Preparation of pzt thin films on Pt/Ti/SiO2 and Pt/SiO2 Substrates by ECR Plasma Enhanced DC Magnetron Multi-target Reactive Sputtering
Authors: Kim Sung-Tae , Kim Hyun-Ho , Lee Moon-Yong , Lee Won-Jong
Published: April 2011

Perovskite-phase lead zirconate titanate (PZT) thin films were fabricated at 4751C by the electron cyclotron resonance (ECR) plasma enhanced DC magnetron multi-target reactive sputtering method on Pt/Ti/SiO2/Si and Pt/SiO2/Si substrates. Stoichiometric perovskite PZT films were readily obtained on Pt/Ti/SiO2/Si substrates because Ti atoms which were out-diffused to the Pt surface facilitated Pb incorporation by forming lead titanate at the early stage of deposition process. Activation of oxygen by ECR plasma facilitated the oxidation reaction and Pb incorporation into the film. Thus perovskite-phase PZT can be obtained on the Pt/SiO2/Si substrate.
Diffusion Barrier Reliability with Respect to the Role of Tin Stoichiometry Between Al Metallization and Si Substrate
Authors: Tseng Han-Yu , Christou Aris , Young Dan , Tessner Ted , Orloff Jon
Published: April 2011

In this study, the relation between interdiffusion in Al/ TiN thin film couples and diffusion barrier stability has been investigated. The TiN diffusion barrier was deposited by reactive sputtering in an Ar-N2 gas mixture. The stoichiometry of TiN was achieved by varying the nitrogen-to-argon ratio in the sputtering gas. Interdiffiusion occurred after annealing for 30 minutes at 475°C and 575°C. Diffusion processes and interfacial reactions with respect to TiN stoichiometry were investigated via Auger Electron Spectroscopy (AES) depth profiling and X-ray diffraction (XRD). The barrier reliability with respect to the stoichiometry changes was established; nitrogen-deficient TiN films result in a high degree of interdiffiusion and decomposition at annealing temperatures of 475°C and 575°C. AI3Ti and AlN intermetallic compounds were formed at the interfaces. The sheet resistance of Al films was measured by four-point probe method. Resistance increases for all the annealed films were due to interdiffusion between Al and TiN. The degree of interdiffusion was analyzed by using AES and XRD.
(100) Oriented Platinum thin Films Deposited by Dc Magnetron Sputtering On SiO 2/Si Substrates
Authors: Park Dong-Yeon , Lee Dong-Su , Kim Min Hong , Park Tae-Soon , Woo Hyun-Jung , Yoon Euijoon , Chun Dong-ll , Ha Jowoong
Published: April 2011

Platinum(Pt) films were sputter-deposited on Si02/Si substrates under the mixed gas atmosphere of Ar and O2. Under certain deposition conditions, the films were oriented such that the (100) direction is normal to the substrate surface. The formation of the (100) texture was affected by the gas pressure and film thickness. After annealing at 650 °C for 1 hour, (100) oriented Pt films with the resistivity of pure Pt were obtained. The annealed Pt films all passed a tape adhesion test and had no defects such as hillocks or pinholes. The experimental results from this work are presented.
In-Situ Measurements of Islanding and Strain Relaxation of Ge/Si(111)
Authors: Deelman P. W. , Schowalter L. J. , Thundat T.
Published: April 2011

We have measured strain relaxation and islanding in Ge films grown by molecular beam epitaxy on Si(111) at substrate temperatures between 450°C and 700°C in real time with reflection high energy electron diffraction (RHEED). At 450°C, we observe an oscillation of the surface lattice parameter for the first three bilayers (BL), followed by a sharp 2D–3D growth mode transition, when transmission diffraction features appear in RHEED. The surface lattice parameter then begins to relax at an initial rate of about 0.5%/BL. The mechanisms of island growth and strain relaxation change with growth temperature. At 500°C the surface lattice parameter begins to relax after only 1BL; at 550°C relaxation begins immediately. However, 3D spots do not appear until after 3.5BL at either temperature. The initial rate of strain relaxation decreases with increasing temperature until, at 700°C (when 3D spots never appear), it is only 0.04%/BL. This behavior may be explained by a temperature-dependent roughness length scale, as well as by differences in dislocation nucleation at low and high temperatures. At low temperature, atomic force microscope images show the development of small (1000Å), faceted islands with aspect ratios (height/width) on the order of 0.07. The formation of well-defined facets is inhibited at higher temperatures. At 700°C, islands grow very large (lμm) from the outset, with aspect ratios less than 0.015. These islands cannot thicken much, because dislocations can glide in easily at their edges. The islands grow laterally quickly, and the strain in the “new” islands is not substantially less than that in the “old.” At 700°C, 28% of the Ge/Si misfit strain may be relieved by diffusion.
Stress of Platinum Thin Films Deposited by Dc Magnetron Sputtering Using Argon/Oxygen Gas Mixture
Authors: Kim Min Hong , Park Tae-Soon , Lee Dong-Su , Lee Yong Eui , Park Dong-Yeon , Woo Hyun-Jung , Chun Dong-Il , Yoon Euijoon , Ha Jowoong
Published: April 2011

Pt thin films were deposited by a DC magnetron sputtering with Ar/O2 gas mixtures. Due to the oxygen incorporation into the Pt films, deposition rate and resistivity of as-deposited Pt thin films increased with oxygen fraction in the sputtering gas. No peaks from crystalline Pt oxides were observed by x-ray diffraction (XRD) and excessive oxygen incorporation into Pt lead to an amorphous Pt oxide formation. More oxygen could be incorporated in the Pt thin films deposited at lower temperatures and at higher total pressures. Incorporated oxygen was completely removed after an annealing at 800 °C for an hour in air ambient, as the resistivity of the Pt thin films recovered their bulk resistivity values. Tensile stress of the Pt films decreased with oxygen incorporation, and approached a saturation level at high resistivity of the films, presumably due to the formation of amorphous Pt oxides.
3-D Atomistic Kinetic Monte Carlo Simulations of Point Defect Incorporation During CVD Diamond Film Growth
Authors: Battaile C. , Srolovitz D. J. , Butler J. E.
Published: April 2011

The incorporation of vacancies and H atoms into { 100}- and { 111 }-oriented diamond films during CVD growth in an atmosphere of H, H2, CH3, and C2H2is simulated atomistically. The growing films are represented in three dimensions by a diamond cubic lattice, and the temporal evolution of the surfaces is accomplished by a kinetic Monte Carlo method. The dimer bonding of diamond atoms on the { 100} surface is treated explicitly. Growth begins on { 100}(2xl):H and { 11 }:H surfaces containing 288 and 300 atoms, respectively, in the surface plane, and the growth of approximately sixty atomic layers (18,000 atoms) is accomplished at each of fifteen substrate temperatures between 800 and 1500 K. The growth rates depend on the combined contributions to growth from CH3and C2H2, whereas the point defect concentrations depend on the ratio of C2H2to CH3growth. The maximum { 100} growth rate is achieved at approximately 1200 K. Point defect concentrations are low at temperatures below 1300 K, but become high above 1300 K. Growth efficiency, defined as the ratio of growth rate to defect concentration, is maximum for both film orientations at substrate temperatures in the vicinity of 1100 to 1200 K.
Cluster Model Study to the As2-Adsorption on GaAs(001)-Surfaces
Authors: Marek T. , Strunk H. P. , Kunsági-Máté S. , Mareka N.
Published: April 2011

We study by using ab-initio methods the adsorption of As2-molecules on a Gaterminated GaAs(001) surface. We represent the GaAs crystal by a Ga5As2H8 cluster, which is large enough to resemble the crystal but sufficiently small to be tractable in a computer in a reasonable time. We calculate the reaction path along the symmetry axis C2 of this cluster and obtain the reaction path by minimizing the total energy of the system (cluster plus molecule). In the calculated positions above the cluster we account for the possibility of the As2-molecule to rotate around the C2 symmetry axis and for a change in the distance between the As-atoms. As a main result we obtain that for heights above the (001) surface less than about 3.5A we find a clear influence of the discrete atomic surface structure on the reaction path of the As2-molecule.
Morphology Studies of Oxide Films Deposited by Rf Plasma Technique
Authors: Hunt D. J. , Moss R. W. , Olson J. E. , Lee D. H. , Wang X. W.
Published: April 2011

Recently, an energetic film growth technique was developed. In this process, an RF (radio frequency) plasma was ignited in an ambient atmospheric environment. An aqueous solution was excited into mist, which was then fed into the plasma reactor. After vaporization, films were formed on substrates outside the plasma. As a by-product, small amount of powders were collected in the plasma reactor. Films studied were indium-tin oxide (ITO), aluminum oxide (Al2O3), and lanthanum strontium manganite oxides (LaSrMnO). Films and powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX, EDS), and Ultraviolet-Visible (UV-Vis) transmission measurements. Morphology of a film surface was dependent on deposition conditions, such as chemical composition of the precursor materials, precursor feeding rate, and/or substrate temperature.
Nonlinear Optical Mapping of Cubic Silicon Carbide Micron Areas In Epitaxial Films of Hexagonal Polytypes
Authors: Lüpke G. , Meyer C. , Busch O. , Kamicuski E. Stein von , Göz A. , Kurz H.
Published: April 2011

Various silicon carbide polytypes, such as 4H-, 6H- and 3C-SiC are clearly distinguished by the magnitude and rotational anisotropy of their optical second-harmonic (SH) response. The large dynamic range of the SH response of more than two orders of magnitude between these polytypes allows a fast and non-invasive mapping of 3C-SiC micron areas in 4H - and 6H-SiC epilayers. 3C-Microcrystallites of different oricutations are identified from SH rotational anisotropy scans.
Multilayer Fresnel Zone Plate For 8KeV X-Ray by DC Magnetron Sputtering Deposition
Authors: Tamura S. , Mori K. , Maruhashi T. , Yoshida K. , Ohtani K. , Kamijyo N. , Suzuki Y. , Kihara H.
Published: April 2011

Hard X-ray microprobes from synchrotron radiation ( SR ) sources should be powerful tools for various fields of research. A Fresnel zone plate ( FZP ) is a promising focusing element for X-ray. In order to develop high performance multilayer FZP for use in hard X-ray region, Ag/C and Cu/Al concentric multilayers were prepared by some deposition parameters. A dependence of the zone boundary structures on the Ar gas pressure was observed: the multilayer prepared at lower Ar gas pressure had smoother zones. Substrate cooling did not improve the zone boundary structures. From the focusing test of the Cu/Al FZP by the SR, a microbeam of 1.3 μ m ø has been obtained for 8 KeV X-ray (λ =0.154nm).
Reliability Improvement of Aluminum Wirebonds in High‐Power Igbt Modules
Authors: Wu Yujing , Thome Gene , Scott Savage Timothy
Published: April 2011

Wirebonding is the weakest area of device packaging of power IGBT modules. Accelerated thermal fatigue testing causes cracks to form and propagate in the aluminum wirebond at the foot area. This study examined the relationship of the wirebond reliability and the aluminum wire grain structure, which can be affected by post‐wirebond heat treatment. A series of wirebonded IGBTs were annealed at a temperature range from 280°C to 400°C for up to 60 minutes. Wirebond shear strengths versus temperature cycles were examined. Cross‐sectional SEM was used to examine both aluminum grain size development by annealing and crack initiation and propagation in the wirebonds after temperature cycling. It was found that aluminum grain size was increased by post‐wirebond annealing. With temperature cycling, the wirebond shear strengths of the as‐wirebonded samples decrease rapidly, and lifted wirebonds were present after 1500 temperature cycles. The lifted wirebonds typically break within the aluminum wire near the wire/metallization interface. The shear strength of the wirebonds with post‐wirebond annealing showed no significant change even after 5000 temperature cycles, and there were no signs of significant deterioration of the wirebonds either. The wirebond crack initiation and growth rates were depressed substantially by larger aluminum grains. Annealing of the aluminum wire after wirebonding provided increased aluminum grain size resulting in improved reliability of the wirebonds of high power modules.
Application Of Electroless Copper Plating Technology For Thin Film Laminated Multilayer Wiring Board
Authors: Itabashi T. , Akahoshi H. , Takahashi A. , Suzuki M. , Maeda M.
Published: April 2011

A thin film laminated high density multilayer wiring board was developed using electroless copper plating technology. The basic steps in the fabrication process are: laminating the high heat resistant polymer film, forming via holes by plasma etching and filling them by electroless copper metallization. The 25 μm diameter via holes can be completely filled with copper using the selective electroless plating method. This paper describes the fabrication process, focusing particularly on electroless copper plating.
High-Quality Photoconductive Ultraviolet GaN/6H-SiC Detector and Its Properties
Authors: Yang K. , Zhang R. , Zang L. , Shen B. , Chen Z.Z. , Zheng Y.D. , Bao X. M. , Huang Z.C. , Chen J.C.
Published: April 2011

The properties of photoconductive ultraviolet detector based on GaN epilayer grown on 6H-SiC substrate by metalorganic chemical vapor deposition were investigated in this paper. We obtained the detectable energy span of the device up to ultraviolet by photocurrent measurement. The spectral responsivity remained nearly constant for wavelengths from 250 to 365 nm and dropped by three orders of magnitude within 10 nm of the band edge (by 380 nm). The detector was measured to have a responsivity of 133 A/W at a wavelength of 360 nm under a 5-V bias, and the voltage-dependent responsivity was performed. Furthermore, an easy method was developed to determine the response time, and the relationship between response time and bias was obtained.