bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultra Thin Sacrificial Diffusion Barriers - Control of Diffusion Across the Cu-SiO2 Interface
Authors: Kirchner Eric , Murarka S.P. , Eisenbraun E. , Kaloyeros A. 
Published: March 2011

ABSTRACTIn a copper-SiO2 dielectric multilevel interconnection scheme a diffusion barrier is needed between the metal and the dielectric to prevent the diffusion of Cu into SiO2 when subjected to thermal treatments and high electric bias. Ultra thin layers (50–100Å) of Al and Ti are being investigated for use as the required diffusion barrier as well as an adhesion promoter between Cu and SiO2 The results of our investigations, using C-V, resistance, and XPS measurements, will be presented and discussed. It will be shown that both Al and Ti reduce the SiO2 surface leading to a metal, oxygen, and Si bonded layer which acts as diffusion barrier under applied electrical bias of 1.5 MV/cm at temperatures as high as 250–300°C. Upper layers of Al and Ti are consumed by reaction with Cu. Such reactions increase the electrical resistivity and corrosion resistance of Cu (especially with Al). The results and the applicability of such barriers in practical cases will be presented and discussed.
Thermal and Electromigration Effects on the Surface and Aluminum/Aluminum Oxide Interface of Aluminum Metallizations
Authors: Ramseyer George O. , Beasock Joseph V. , Sylla William K. , Walsh Lois H. 
Published: March 2011

ABSTRACTThermal and electromigration effects on the thicknesses of aluminum oxide at the aluminum-1% silicon/thermal silicon dioxide interface were quantitatively determined by AES. Void sites corresponded with thinner aluminum oxide thicknesses at this interface. Changes in surface topography and grain structure were quantitatively determined for thermally annealed aluminum-1% silicon metallizations by AFM.
Electrical, Magnetic and Mechanical Properties of Nanocrystalline Nickel
Authors: Aus M.J. , Szpunar B. , Erb U. , Palumbo G. , Aust K.T. 
Published: March 2011

ABSTRACTThe electrical, magnetic and mechanical properties of bulk nanocrystalline nickel produced by pulse-electrodeposition are reviewed and discussed in the context of nanoprocessing as a distinct form of grain boundary engineering to develop soft magnetic materials with improved performance characteristics.
Enhanced Ionic Conduction at the Film/Substrate Interface in LiI Thin Films Grown on Sapphire(0001)
Authors: Lubben D. , Modine F. A. 
Published: March 2011

ABSTRACTThe ionic conductivity of LiI thin films grown on sapphire(0001) substrates has been studied in situ during deposition as a function of film thickness and deposition conditions. LiI films were produced at room temperature by sublimation in an ultra-high-vacuum system. The conductivity of the Lil parallel to the film/substrate interface was determined from frequency-dependent impedance measurements as a function of film thickness using Au interdigital electrodes deposited on the sapphire surface. The measurements show a conduction of ∼5 times the bulk value at the interface which gradually decreases as the film thickness is increased beyond 100 nm. This interfacial enhancement is not stable but anneals out with a characteristic log of time dependence. Fully annealed films have an activation energy for conduction (σT) of ∼0.47 ± .03 eV, consistent with bulk measurements. The observed annealing behavior can be fit with a model based on dislocation motion which implies that the increase in conduction near the interface is not due to the formation of a space-charge layer as previously reported but to defects generated during the growth process. This explanation is consistent with the behavior exhibited by CaF2 films grown under similar conditions.
Switching and Negative Capacitance in Thin Amorphous SiC-Si Heterojunction Diode
Authors: Sohn K. , Lee H. 
Published: March 2011

ABSTRACTThe heterojunction diode of amorphous SiC-pSi with barrier contacts in which the interface layer, a-SiC, is much less than 100 nm and contains considerable defect densities, exhibited bistable switching with memory. Either state was maintained over weeks without bias. A high-impedance state switched to a low-impedance state with the transient on-state when a threshold voltage was exceeded. After application of current pulses, a low-impedance switched to a high-impedance state. In C-V Measurement, novel negative capacitance phenomenon in the entire bias range which has not been reported yet was demonstrated. Experimental results show that this negative capacitance is due to the inductive reactance. This phenomenon presents the possibility of replacing inductor even at zero bias.
Photodarkening Effect Dependent on Alkaline Metal Dopants in Semiconductor - Doped Glass
Authors: Yanagawa T. , Nakano H. 
Published: March 2011

ABSTRACTThis report clearly shows that the photodarkening effect in semiconductor-doped glasses comes from the color center formation of alkaline silicate glass. It also discusses the cause of response time shortening after darkening. It seems that fast and stable responses can be obtained with a specific alkaline metal composition, showing a change in the dielectric properties and also a drastic decrease in the ion conductivity based on the mixed-alkali effect. After-darkening phenomena, such as the absorption increase in all transparent region of the glass, the appearance of electron spin resonance (ESR) arising from the formation of glass color centers, and matrix glass changes observed with a field emission scanning electron microscope (FE-SEM), are distinctly shown.
Structural and Electrical Properties of BaTio3 Thin Films Grown on p-Si Substrates with Different Device Designs
Authors: Chang L. H. , Jia Q. X. , Anderson W. A. 
Published: March 2011

ABSTRACTRF magnetron sputtering of BaTiO3 on (100) p-Si was performed to produce a high-quality BaTiO3/p-Si interface and BaTi03 insulator gates with high dielectric constant and low leakage current. Through different processing and device designs, different capacitor structures, including single layer amorphous, single layer polycrystalline and bi-layer amorphous on polycrystal-line, were investigated in this study. Raman spectroscopy showed the optical phonon modes of the BaTiO3 thin films with different structures. The structural properties of the films were characterized by X-ray diffraction. Using both the quasistatic and the high-frequency capacitance-voltage measurements, the interface-trap density was estimated at high 1011 eV−1 cm−2. The relative dielectric constant of the composite structure was controlled in a range from 30 to 130. The leakage current density was as low as 8×10−10 A/cm2 at a field intensity of (2±0.5)×105 V/cm. Breakdown voltage varied from 5x105 to 2×106 V/cm.
Effect of Doping on the Interface States in Au Schottky Contact to p-In0.21Ga0.79As Grown on GaAs by Metal Organic Vapour Phase Epitaxy
Authors: Singh A. , Cova P. , MASUT R. A. 
Published: March 2011

ABSTRACTEpitaxial p-In0.21Gao0.79As/Au Schottky barrier type diodes were fabricated by evaporation of Au on chemically etched surfaces of In0.21Ga0.79As:Zn layers grown on highly doped GaAs substrate by MOVPE. 1 MHz capacitance-voltage (C-V) and Capacitance-frequency (C-f) measurements were performed in the frequency range 1 KHz-1 MHz at room temperature in Au Schottky diodes made on four epitaxial In0.2 Ga0.79As:Zn samples with doping concentrations between 6×1014cm−3 and 4×1017 cm−3. Under forward bias, a large frequency dispersion in the junction capacitance was observed which was attributed to the interface states in thermal equilibrium with the semiconductor. The interface states capacitance extracted from the C-f data was analyzed in terms of Lehovec's theoretical model of interface state continuum with single time constant, and the characteristic parameters of the interface states (energy density (Nss), relaxation time (τ) and hole capture cross-section (σh)) were determined. In the samples with doping concentration in the range 1.5×1017-4.3×1017 cm−3, Nss was about an order of magnitude higher than in the sample having a doping concentration of 5.8×1014 cm−3. Over the interface states energy range 0.40-0.65 eV, Nss decreased exponentially with energy in the highly doped samples and σh increased with energy in all the samples.
Solid-State Reactions of a 3D-Transition Metal-Ti/Al2O3 System
Authors: Suenaga Seiichi , Koyama Miho , Arai Shinji , Nakahashi Masako 
Published: March 2011

ABSTRACTAn interfacial mechanism for reactions between a Me-Ti thin film (Me=3d transition metals; Cu,Ni) and an A12O3 substrate is newly proposed. It has been clarified that Me3Ti3O (diamond cubic of Fd3m), which is formed as an intermediate phase in both the Cu-Ti/Al2O3 and Ni-Ti/Al2O3 systems, is responsible for the bonding between Me and A12O3. The solid-state reactions of the Me-Ti bilayer film/Al2O3 system were studied with Auger electron spectroscopy (AES) and X-ray diffraction (XRD) to clarify the interfacial reaction between Me-Ti and the A12O3 substrate. Me3Ti3O was observed at the interface between A12O3 and Me after annealing. Me3Ti3O was formed by oxidation of the Me-Ti compounds. The oxygen which reacted with the Me-Ti compounds has been found to be generated from the reduction of the A12O3 substrate.
Liquid Infiltration of MgO and Al2O3 Thin Films
Authors: Mallamaci Michael P. , Ramamurthy Sundar , Barry Carter C. 
Published: March 2011

ABSTRACTThe deposition of glass films on thin ceramic substrates is a novel method for investigation of the initial stages of liquid infiltration into the grain boundaries of these materials. By maintaining electron transparency at all stages of the experiment, the transmission electron microscope (TEM) can be used to characterize individual grain boundaries before and after penetration by a liquid. The method has been tested for the MgO and AI2O3 systems, which have extensively studied experimental counterparts in which the corresponding bulk materials are infiltrated by a siliceous liquid.
Near Interface Oxide Degradation in High Temperature Annealed Si/SiO2/Si Structures
Authors: Devine R. A. B. , Mathiot D. , Warren W. L. , Fleetwoodi D. M. 
Published: March 2011

ABSTRACTDegradation of 430 nra thick SiO2 layers in Si/SiO2/Si structures which results from high temperature annealing (1320°C) has been studied using electron spin resonance, infra-red absorption spectroscopy and refractive index measurements. Large numbers of oxygen-vacancies are found in a region ≤ 100 nm from each Si/SiO2 interface. Two types of paramagnetic defects are observed following γ or X-irradiation or hole injection. The 1106 cm−l infra-red absorption associated with O interstitials in the Si substrate is found to increase with annealing time. The infra-red and spin resonance observations can be explained qualitatively and quantitatively in terms of a model in which oxygen atoms are gettered from the oxide into the under or overlying Si, the driving force being the increased O solubility limit associated with the anneal temperature.
Electrostatic Potentials for Metal Oxide Surfaces and Interfaces
Authors: Streitz F. H. , Mintmire J. W. 
Published: March 2011

ABSTRACTWe discuss the development of interaction potentials which explicitly allow for charge transfer in metallic oxides. The charge transfer is calculated self-consistently using a charge equilibration approach, which allows the amount of charge transferred to respond to the electrostatic environment. We model the metal-metal, metal-oxygen, and oxygen-oxygen interactions with Rydberg function pair potentials. By fitting the Rydberg potential parameters to the elastic and structural constants of the material, we arrive at an efficient model for the simulation of metallic oxides. We demonstrate the applicability of the model by describing some preliminary results on the rutile phase of titanium dioxide.
Stress Driven Patterning of Epitaxial Films
Authors: Grinfeld Michael A. 
Published: March 2011

ABSTRACTWe study possible morphologies of epitaxial films atop attractive substrates appearing as a result of competition of misfit stresses, van der Waals forces and surface energy. Corresponding formula for the critical thickness of the dislocation-free Stranski-Krastanov pattern is established for the isotropic deformable films and substrates. If the film thickness exceeds the critical magnitude the layer-by-layer pattern switches to islanding. At the first stage the islands have a shape of striae (i.e. long parallel trenches with periodic spacing). We discuss also i)the circumstances in which surface morphology of the film corresponds to a two-dimensional superlattice of islands rather than a one dimensional lattice of striae and ii)the influence of a buffer inter-layer.
The Structure and Stress State of Lamellar Interfaces in Two-Phase Titanium Aluminides
Authors: Appel Fritz , Christoph Ulrich , Wagner Richard 
Published: March 2011

ABSTRACTTitanium aluminide alloys with compositions slightly on the Ti-rich side of stoichiometry consist of the intermetallic phases α2 (Ti3Al) and γ(TiAl). The two phases form a lamellar microstructure with various types of coherent and semicoherent interfaces. The lattice mismatch occurring at the semicoherent interfaces is largely accommodated by networks of interfacial dislocations. Nevertheless, a significant homogeneous straining seems to remain at these interfaces, resulting in long-range residual stresses. The present paper reports an electron microscope study of the correlation between the misfit strain of adjacent lamellae and the atomic structure of the interfaces. The residual coherency stresses were determined by analyzing the curvature of dislocation loops which were emitted from the network of the interfacial dislocations. The estimated stresses are close to the shear stresses applied during macroscopic deformation experiments. The effects of these stresses on the deformation behaviour of the material are discussed.
Preparation of Amorphous Ti-Ni Films and Study on the Electrocatalytic Properties
Authors: Weikang Hu , Yunshi Zhang , Deying Song , Zuoxiang Zhou 
Published: March 2011

ABSTRACTThe film electrodes of amorphous Tio.ssNi1.00 and Ti1.59Ni1.00 were prepared by means of ion beam sputtering method using TiNi and Ti3Ni alloy targets, respectively The surface microstructures and chemical states of elements of the two films before and after HF treatment were examined by SEM and XPS. The electrocatalytic properties for hydrogen evolution reaction were measured by the galvanost&tic steady-state method in 1M NaOH at 40°C. The results showed that the surface microstructures and compositions of the treated films obviously changed as compared with the untreated films. The electrocatalytic activities of the both films before treatment were lower, but the electrocatalytic activities and exchange current densities significantly increased after treatment.
X-Ray Studies of Low-Temperature Grown Sio2 on Si
Authors: Baribeau J.-M. , Landheer D. , Bardwell J.A. , Clark K.B. , Headrick R.L. 
Published: March 2011

ABSTRACTX-ray reflectivity has been used to study properties of thin SiO2 films on (100) Si prepared by plasma-enhanced chemical vapor deposition (PECVD) or by anodic oxidation. Reflectivity curves were analyzed to obtain information concerning the thickness, density (p) and interface roughness (σ) of these oxide films. We found that the PECVD films have typically a density of 0.98 psi with a sharp Si/SiO2 interface (σ < 0.2 nm) and a surface roughness of -0.5 nm. Anodic oxide films have a lower density (p = 0.88 psi) and larger interface and surface roughness σ - 0.5 nm. High temperature annealing of the anodic oxides up to 900 °C resulted in no appreciable densification but caused an increase in the interfacial roughness. Considerable variations were observed in the reflectivity curves from a PECVD oxide film annealed in the 650-1050 °C range.-Modeling of these results suggests the existence of a thin interfacial layer (-0.5 nm) of less density (∼0.9psi) at the original silicon/PECVD oxide interface.
Characterization of thin Chemical/Native Oxides on Si (100) by Auger and Angle-Resolved XPS
Authors: Pylant Eddie D. , Hoener Carolyn F. , Arendt Mark F. , Witowski Bob 
Published: March 2011

ABSTRACTChemical/native oxides grown on Si(100) after several standard wet cleans are characterized by Angle-resolved X-ray Photoelectron Spectroscopy (ARXPS), and Auger Electron Spectroscopy using sputter depth profiles. Target Factor Analysis (TFA) was used to separate the Si LVV Auger peak into three components identified by their lineshapes and positions as Si, SiO2, and SiOx- Auger depth profiles were used to quantify the thickness of the oxides, the depth distribution, and amount of SiOx in the interface region. ARXPS was used to study the chemical state distribution in the native oxides as a function of depth. The depth distribution function from the Auger data was converted to an angle-resolved format for direct comparison to the angle-resolved XPS data. With this comparison, the SiOx lineshape is correlated to a 3:1 mixture of Si 3+ and Si 2+ oxidation states.
Structure and Properties of Vanadium Pentoxide Gels
Authors: Livage J. 
Published: March 2011

ABSTRACTTransition metal oxide gels can be obtained, through a polycondensation process, by acidification of aqueous solutions. Thin layers can be easily deposited onto a substrate. Their electronic and ionic properties could lead to new developments of the sol-gel process. The semiconducting properties of V2O gels can be used for antistatic coatings or electrical switching devices. These gels exhibit a lamellar structure and can be described as particle hydrates. They are fast proton conductors and could behave as a host lattice for intercalation.
Electrical Properties of Na2O - SiO2 Dried Gels
Authors: Ravaine D. , Traore J. , Klein L. C. , Schwartz I. 
Published: March 2011

ABSTRACTGels with compositions Na2O-(1-x)SiO2 were prepared from tetraethylorthosilicate (TEOS) with sodium acetate and from tetramethylorthosilicate (TMOS) with sodium methoxide or TEOS with sodium ethoxide. After gelation (10 min.) the samples were slowly dried for about one month at room temperature. Thermogravimetric analysis (up to 500°C) in air and O2 atmosphere was performed. The electrical properties were studied in air by impedance spectroscopy during successive temperature cycles starting from room temperature dried gels of composition 0.10 Na2O 0.90 SiO2. Protonic conductivity appears to be eliminated after reaching the 2nd stage of the drying process (200°C). The activation energies for conduction and the conductivities show small discrepancies from known values for homogeneous glasses of equivalent compositions. Considering the effect of water on the conductivity of glasses prepared by the melting procedure, one can estimate the residual water content in the so-called dried gels to be close to 0.5 wt %.
Preparation of Barium Titanate Films Using Sol-Gel Techniques
Authors: Dosch R. G. 
Published: March 2011

ABSTRACTSol-gel techniques provide a convenient method of applying barium titanate films on solid substrates at ambient temperature. A significant advantage in using this technique is the capability of maintaining compositional homogeneity while coating large areas of surfaces with complex geometries. Solutions prepared by reacting a titanium alkoxide with barium hydroxide in methanol were used for preparing thin films (1000–3000Å) of barium titanate on silicon and metal substrates. Electrical properties of the films depended both on solution parameters and subsequent heat treatment of the films. Highest field strengths (8−9 × 106 V/cm) were observed in amorphous films prepared from partially hydrolyzed solutions.
Glasses and Ceramics from Colloids
Authors: Scherer G. W. 
Published: March 2011

ABSTRACTFlame-generated particles can be suspended in a nonpolar solvent, molded, and gelled. The microstructure obtained after solvent evaporation depends on the characteristics of the colloid. Higher solids loadings lead to denser green bodies and narrow pore size distributions. The mean pore size is proportional to the particle size. Sintering occurs at relatively low temperatures, producing amorphous or crystalline bodies of high purity.
A Comparison Between the Densification Kinetics of Colloidal and Polymeric Silica Gels
Authors: Brinker C. J. , Drotning W. D. , Scherer G. W. 
Published: March 2011

ABSTRACTSilica gels were prepared by three methods in which the original silicate species varied from extended linear or randomly branched polymers to more highly crosslinked clusters to colloidal particles of anhydrous silica. During isothermal sintering experiments, the viscosities of the two polymer gels increased significantly (up to 3 orders of magnitude) while the isothermal viscosity of the colloidal gel was constant. Viscosity increases were explained by crosslinking and structural relaxation of the polymeric gels.
Effect of Aging on Electrophoretic Behavior of Sol-Gel Derived Aluminas
Authors: Lee Burtrand I. , Hench Larry L. 
Published: March 2011

ABSTRACTSample alumina powder prepared with the procedures described by Yoldas [1,2] was suspended in 10−3 M NaCl and contained in precleaned polypropylene cups with air tight lids. Electrophoretic mobilities of the samples were measured at various pH's using a microelectrophoretic technique. The points of zero charge (PZC) were determined from plots of electrophoretic mobility vs pH of the sample suspensions. The initial values of PZC are 10.6 for γ-A12O3. and 8.3 for αAl-2O3 , The corresponding BET surface areas are 206 m2/g and 3m2/g respectively. Upon aging, the PZC decreased in 2 days and then increased by reaching maximum values of 10.4 for γ-Al2 O3 and 8.8 for α-Al2 O3 in 20 days. Aging of sol-gel derived aluminas and commercial alumina derived by precipitation are compared and differences are discussed.
Composition and Chemical Structure of Nitrided Silica Gel
Authors: Brow R. K. , Pantano C. G. 
Published: March 2011

ABSTRACTSol/gel derived silica thin films were thermally treated in NH3for four hours at temperatures up to 1300C. The films were analyzed by ellipsometry, X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). Over 30 mol% nitrogen was incorporated in the film treated at 1300C. Using IR and XPS analyses, -NHxgroups were found to be present after low temperature treatments, while nitrogen was incorporated in an oxynitride structure after the higher temperature treatments.
Gel Structures in Leached Alkali Silicate Glass
Authors: Bunker Bruce C. , Headley Thomas J. , Douglas Sally C. 
Published: March 2011

ABSTRACTTransmission electron microscopy of leached NaOċ3SiO2 and K2Oċ3SiO2 glasses showed that the hydrateg glass surface is a silica rich gel which phase separates during leaching. Phase separation is initiated when pockets of an aqueous phase nucleate and grow in the hydrated silica matrix. The aqueous pockets eventually become a network of interconnected pores with a pore diameter of ∼30 nm. In advanced stages of leaching, the remaining interconnected silica rich phase resembles an aggregation of colloidal silica particles. The observed phase separation is consistent with literature models concerning the chemistry of silica in aqueous solutions and in leached glass.
Strength of Gel-Derived SiO2 Fibers
Authors: LaCourse William C. 
Published: March 2011

ABSTRACTStrengths of as drawn gel-derived SiO2 fibers are found to depend on H2O and alcohol content of the sol, as well as drawing viscosity. Additional factors, including fiber diameter and drying and consolidation schedules are found to dramatically influence strengths of the consolidated glass fibers.