bluuebunny/crossref_metadata_2025 huggingface dataset:
Reply to “Comment on ‘Hydrophobic effects on partial molar volume’ ” [J. Chem. Phys. 123, 167103 (2005)]
Authors: Imai Takashi , Hirata Fumio
Published: October 2005

In the Comment on our paper [J. Chem. Phys. 123, 167103 (2005), preceding paper], Graziano argues based on the scaled particle theory that the partial molar volume change in the transfer of a hydrophobic solute from “hypothetical nonpolar water” to water can be explained simply by the difference in the effective size of solvent molecules. Opposing to the argument, we clarify using the reference interaction site model theory that the attractive interactions represented by the hydrogen bonding play an essential role for the volume change, and that the explanation given by Graziano replaces the real physics by a fake model based on an “effective” molecular diameter. We also make a general argument against the use of hard-sphere models when one considers the properties of hydration.
Electrolyte diodes with weak acids and bases. I. Theory and an approximate analytical solution
Authors: Iván Kristóf , Simon Péter L. , Wittmann Mária , Noszticzius Zoltán
Published: October 2005

Until now acid-base diodes and transistors applied strong mineral acids and bases exclusively. In this work properties of electrolyte diodes with weak electrolytes are studied and compared with those of diodes with strong ones to show the advantages of weak acids and bases in these applications. The theoretical model is a one dimensional piece of gel containing fixed ionizable groups and connecting reservoirs of an acid and a base. The electric current flowing through the gel is measured as a function of the applied voltage. The steady-state current-voltage characteristic (CVC) of such a gel looks like that of a diode under these conditions. Results of our theoretical, numerical, and experimental investigations are reported in two parts. In this first, theoretical part governing equations necessary to calculate the steady-state CVC of a reverse-biased electrolyte diode are presented together with an approximate analytical solution of this reaction-diffusion-ionic migration problem. The applied approximations are quasielectroneutrality and quasiequilibrium. It is shown that the gel can be divided into an alkaline and an acidic zone separated by a middle weakly acidic region. As a further approximation it is assumed that the ionization of the fixed acidic groups is complete in the alkaline zone and that it is completely suppressed in the acidic one. The general solution given here describes the CVC and the potential and ionic concentration profiles of diodes applying either strong or weak electrolytes. It is proven that previous formulas valid for a strong acid-strong base diode can be regarded as a special case of the more general formulas presented here.
Electrolyte diodes with weak acids and bases. II. Numerical model calculations and experiments
Authors: Iván Kristóf , Wittmann Mária , Simon Péter L. , Noszticzius Zoltán , Šnita Dalimil
Published: October 2005

This is the second part of our work dealing with electrolyte diodes with weak acids and bases. In the first part an approximative analytical solution was derived for the steady-state current-voltage characteristic (CVC) of a reverse-biased diode (a quasi-one-dimensional gel connecting an acidic and an alkaline reservoir), applying either strong or weak electrolytes. An approximative analytical solution is compared here with a numerical solution free of any approximations and with CVCs measured experimentally with both strong and weak electrolytes. It is shown that the deviations between the numerical and analytical solutions are mostly due to assumptions made for the fixed charge concentration profiles. The concept of optimal analytical solution is introduced which does not use such assumptions and applies only the quasielectroneutrality and quasiequilibrium approximations. It is proven that the slope of the CVC based on the optimum analytical solution can be calculated without the complicated derivation of that solution itself. The calculation of that slope is based on the fact that in the optimum analytical solution all currents are inversely proportional to the length if the boundary conditions are held constant and realizing that in the middle part of the gel the only mobile counterions of the fixed ionized groups are hydrogen ions. In the experimental part the apparatus and the preparation of the gel are described together with the CVCs measured with strong and weak electrolytes. From these CVCs the fixed ion concentration in the middle part of the gel can be determined. That fixed ion concentration is 1.96×10−4M measured with weak electrolytes and 3.48×10−4M measured with strong electrolytes. The deviation indicates that the strong base causes some hydrolysis of the gel. Finally, possible applications of weak acid-weak base diodes are discussed.
About the calculation of exchange coupling constants using density-functional theory: The role of the self-interaction error
Authors: Ruiz Eliseo , Alvarez Santiago , Cano Joan , Polo Víctor
Published: October 2005

The effect of the correction of the self-interaction error on the calculation of exchange coupling constants with methods based on density-functional theory has been tested in simple model systems. The inclusion of the self-interaction correction cancels the nondynamical correlation energy contributions simulated by the commonly used functionals. Hence, such correction should be important in the accurate determination of exchange coupling constants. We have also tested several recent functionals to calculate exchange coupling constants in transition-metal complexes, such as meta-GGA functionals or new formulations of hybrid functionals. The influence of the basis set and of the use of pseudopotentials on the calculated J values has also been evaluated for a Fe(III) dinuclear complex in which the paramagnetic centers bear several unpaired electrons.
Magnetic-field tunable terahertz quantum well infrared photodetector
Authors: Savić Ivana , Milanović Vitomir , Vukmirović Nenad , Jovanović Vladimir D. , Ikonić Zoran , Indjin Dragan , Harrison Paul
Published: October 2005

A theoretical model and a design of a magnetic-field tunable CdMnTe∕CdMgTe terahertz quantum well infrared photodetector are presented. The energy levels and the corresponding wave functions were computed from the envelope function Schrödinger equation using the effective-mass approximation and accounting for Landau quantization and the giant Zeeman effect induced by magnetic confinement. The electron dynamics were modeled within the self-consistent coupled rate equations approach, with all relevant electron-longitudinal-optical phonon and electron-longitudinal-acoustic phonon scatterings included. A perpendicular magnetic field varying between 0 and 5T, at a temperature of 1.5K, was found to enable a large shift of the detection energy, yielding a tuning range between 24.1 and 34.3meV, equivalent to 51.4–36.1μm wavelengths. For magnetic fields between 1 and 5T, when the electron population of the quantum well infrared photodetector is spin polarized, a reasonably low dark current of ≤1.4×10−2A∕cm2 and a large responsivity of 0.36−0.64A∕W are predicted.
Second-harmonic generation in an optically poled azo-dye/polymer film
Authors: Wang Yuxiao , Tai Oliver Y.-H. , Wang C. H.
Published: October 2005

The power dependence of the optical poling process of a new azo chromophore in the polymethylmethacrylate matrix at room temperature has been investigated. The existing theory is found to be inconsistent with the experiment. A simple model based on the rate equation is proposed to describe the writing process of the chromophore/polymer system. The measured growth rate and the plateau second-harmonic generation intensity as induced by all optical poling are found to be in good agreement with the prediction of the simple model.
Single and double photoionizations of methanal (formaldehyde)
Authors: Hochlaf M. , Eland J. H. D.
Published: October 2005

Single and double photoionization spectra of formaldehyde have been measured at 40.81 and 48.37 eV photon energy and the spectrum of the doubly charged cation has been interpreted using high-level electronic structure calculations. The adiabatic double-ionization energy is determined as 31.7±0.25eV and the vertical ionization energy is 33 eV. The five lowest excited electronic states are identified and located. The potential-energy surfaces of the accessible states explain the lack of stable H2CO2+ dications and the lack of vibrational structure. The experimental double-ionization spectrum can be decomposed into two distinct contributions, one from direct photoionization and the second from indirect double photoionization by an inner-valence shell Auger effect.
Rapid silicon outdiffusion from SiC substrates during molecular-beam epitaxial growth of AlGaN∕GaN∕AlN transistor structures
Authors: Hoke W. E. , Torabi A. , Mosca J. J. , Hallock R. B. , Kennedy T. D.
Published: October 2005

Al Ga N ∕ Ga N ∕ Al N transistor structures were grown onto SiC substrates by molecular-beam epitaxy. Under aluminum-rich growth conditions for the AlN nucleation layer, undesirable n-type conduction is observed near the GaN∕AlN interface for even thick (>1000Å) AlN layers. Silicon is identified as the unwanted dopant from secondary-ion mass spectroscopy measurements. Atomic force microscopy surface maps reveal free aluminum metal on AlN surfaces grown under modest aluminum-rich conditions. It is proposed that rapid silicon migration is caused by molten aluminum reacting with the SiC substrate resulting in dissolved silicon that rapidly migrates through the growing AlN layer. This behavior is significantly reduced using a growth flux ratio of aluminum to reactive nitrogen close to unity. The resulting buffer leakage current of the GaN high electron mobility transistor structure is reduced by more than four orders of magnitude.
Field-emission characteristics of carbon nanotube paste layers
Authors: Oh Tae Sik , Yoo Ji Beom , Park Chong Yun , Lee Seong Eui , Lee Jeong Hee , Kim Jong Min
Published: October 2005

A three-dimensional simulator was used to analyze the field-emission mechanism of a carbon nanotube (CNT) emitter layer as a surface electron emitter in a triode structure for field-emission display. An electrostatic image potential was added to the Fowler-Nordheim equation to improve the accuracy of the calculation, and then several important parameters affecting the field-emission characteristics were studied. We calculated the field enhancement factor (β) and emission factor (κ) of the CNT emitter layer using the experimentally obtained current-voltage (I-V) values and the extended Fowler-Nordheim equation by the least-squares-fitting method. By simulating 211 structures, we confirmed the existence of a shielding effect between the emitters and a penetration phenomenon of the anode voltage.
Degradation of gallium nitride quantum dots under 10keV electron-beam injection at low and high excitation densities
Authors: Sieber B.
Published: October 2005

The time evolution of gallium nitride quantum dots luminescence has been recorded in situ in a scanning electron microscope. Electrons of 10keV were injected in a stationary spot in a scanning electron microscope during 30min. Two different regimes were evidenced depending on the beam current density. At low density, the cathodoluminescence (CL) intensity decreased rapidly and a dark spot appeared. At high beam density, the CL intensity decrease was slower, and a dark ring centered on the beam injection location was formed. All the results are coherently interpreted by an enhanced diffusion of nonradiative defects promoted by nonradiative recombinations.
Growth of segmented ZnS nanocones induced by regular occurrence of twins structure
Authors: Li Y. , Qian L. H. , Li W. F. , Yang C. N. , Ma X. L.
Published: October 2005

Segmented ZnS nanocones have been prepared at 1200 °C by thermal evaporation of zinc sulfide powders and catalyst metal tin. The as-synthesized products have been studied by energy-dispersive x-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. Microstructure characterization indicates that the formation of segmented nanocones can be attributed to the effects of regular twins structure. Theoretical analysis reveals that the nonuniform cross sections of nanocones are related to the continuous change of Sn–ZnS liquid droplet’s scale resulting from the supply of Sn atoms during the evaporation. According to microstructure characterization and dimension analysis, the potential formation mechanism of the segmented ZnS nanocones was discussed.
Evaluation of insulator thickness through excitation-wavelength dependence of photoluminescence of CdSe∕ZnS nanocrystals
Authors: Ozasa Kazunari , Nemoto Shigeyuki , Maeda Mizuo , Hara Masahiko
Published: October 2005

We have observed that the photoluminescence (PL) intensity for CdSe∕ZnS nanocrystals (NCs) placed on insulator films depends on excitation wavelength and insulator thickness, and thus the visualization and thickness evaluation of insulator patterns can be achieved by the PL measurement of CdSe∕ZnS NCs. On the basis of the multireflection/interference calculation, the change of the PL intensity according to the thickness/wavelength is attributed to the interference of excitation light. The evaluation of the thickness profile of the insulator pattern is demonstrated for GaAs-oxide ring patterns formed by solution etching of GaAs. The advantages of the thickness evaluation through the PL of CdSe∕ZnS NCs are simplicity in measurement and horizontal resolution up to 10 nm.
Ultraviolet-illumination-enhanced photoluminescence effect in zinc oxide thin films
Authors: Jin Chunming , Tiwari Ashutosh , Narayan Roger J.
Published: October 2005

We report an enhancement effect of ultraviolet illumination on the photoluminescence intensities of zinc oxide thin films. Large-grain ⟨0001⟩-textured zinc oxide thin films were deposited on amorphous-fused silica substrates using pulsed laser deposition. We found that the intensities of excitonic emission and green-band emission increased with ultraviolet light exposure time until a maximum value was achieved. We attribute this ultraviolet radiation enhancement effect to oxygen desorption on the surface of the zinc oxide thin film. We have proposed a phenomenological model to explain this interesting photoluminescence behavior.
Determining a complete three-dimensional set of eigenfunctions for nanoscale structure analysis
Authors: Sullivan Dennis M.
Published: October 2005

With the shrinking dimensions of semiconductor devices, it is becoming increasingly important that the analysis of devices be rooted in quantum mechanics rather than in classical analysis. The starting point in the analysis of structures is the determination of the quantum eigenenergies and the corresponding eigenfunctions. It is particularly desirable to determine a complete set of eigenfunctions as a basis for any quantum analysis. A method based on the finite-difference time-domain formulation is presented that systematically determines an orthonormal basis of eigenstates for submicron structures.
Line-defect-induced bending and splitting of self-collimated beams in two-dimensional photonic crystals
Authors: Lee Sun-Goo , Oh Sang Soon , Kim Jae-Eun , Park Hae Yong , Kee Chul-Sik
Published: October 2005

We show that line defects can give rise to the bending and splitting of self-collimated beams in two-dimensional photonic crystals from the equifrequency contour calculations and the finite-difference time-domain simulations. The power ratio between two split self-collimated beams can be controlled systematically by varying the radii of rods or holes in the line defect. We also show that the bending and controllable splitting of self-collimated beams can be useful in steering the flow of light in photonic crystal integrated light circuits.
Local hysteresis loop measurements by magneto-optical scanning near-field optical microscope
Authors: Schoenmaker Jeroen , dos Santos Antonio Domingues , Seabra Antonio Carlos , Souche Yves , Jamet Jean-Pierre , Thiaville André , Ferré Jacques
Published: October 2005

We performed magnetic-field-induced experiments on micron-sized patterned Co70.4Fe4.6Si15B10 square thin-film elements with in-plane magnetic anisotropy by magneto-optical scanning near-field optical microscopy (MO-SNOM) with a spatial resolution better than 200nm. Markedly different local hysteresis loops (LHLs) were measured on selected positions in one element. Some LHLs presented an unusual shape intrinsic of local magnetic-field-induced process. Comparison of the MO-SNOM imaging results with high-resolution far-field Kerr microscopy has confirmed the local character of the MO-SNOM measurements. This has also helped us to understand the unusual LHLs shapes as related to the field-induced rearrangement of the domain structure within the square element during the magnetization process. The magnetic structure in small field is well described by two overlapping four-domain flux-closure configurations that are well modeled by micromagnetic calculations.
Subwavelength imaging of field confinement in a waveguide-integrated photonic crystal cavity
Authors: Cluzel B. , Gérard D. , Picard E. , Charvolin T. , de Fornel F. , Hadji E.
Published: October 2005

A photonic crystal microcavity is designed to obtain an original field distribution inside the cavity and the structure is etched inside a silicon-on-insulator waveguide. Spectral location of the photonic band gap and cavity resonance are identified by using transmittance measurements and by analyzing the light collected by a scanning near-field optical microscope probe exactly positioned on the center of the cavity. The results obtained with the two techniques are in very good agreement. Then the near-field distribution above the device is mapped and light confinement inside the cavity is evidenced. Moreover, this confined light presents some remarkable patterns which clearly correspond to the cavity mode field distribution computed by using a plane-wave expansion method and taking into account the probe resolution.
Liquid-crystal alignment on a-C:H films by nitrogen plasma beam scanning
Authors: Wu K. Y. , Chen C.-H. , Yeh C.-M. , Hwang J. , Liu P.-C. , Lee C.-Y. , Chen C.-W. , Wei H. K. , Kou C. S. , Lee C.-D.
Published: October 2005

A plasma beam scanning treatment has been developed to modify the surface of the hydrogenated amorphous carbon (a-C:H) film on the indium tin oxide glass. The plasma beam scanning treatment makes the a-C:H film an excellent layer for liquid-crystal alignment. The qualities of a-C:H films were characterized by using atomic force microscope, micro-Raman spectroscopy, and field-emission scanning electron microscope. The ultrathin a-C:H films were deposited at 50% CH4∕(H2+CH4) gas ratio, 100W radio-frequency power, and a gas pressure of 10mtorr for 15min by capacitive-coupled plasma chemical-vapor deposition method. The twist nematic cells were filled with liquid crystal (ZLI-2293) on the a-C:H film treated with different nitrogen plasma beam scanning time. The grooving mechanism is considered not responsible for the liquid-crystal (LC) alignment. Raman spectra suggest that a bond-breaking process of aromatic rings occurs in the a-C:H film. The O1s, C1s, and N1s core-level spectra support that the nitrogen plasma beam scanning treatment induces a bond-breaking process of aromatic rings to create available carbon dangling bonds for the formation of C–O bonds. The newly formed C–O bonds are “directional,” which favor the LC alignment on the a-C:H film.
Generalized models of the spectral response of the voltage for the extraction of recombination parameters in silicon devices
Authors: Mäckel Helmut , Cuevas Andrés
Published: October 2005

Analytical models of the spectral response of the voltage of silicon devices have been generalized using the concept of the internal quantum efficiency of the semiconductor. This allows the extension of models used in the analysis of the internal quantum efficiency to the spectral response of the voltage. Existing models for the spectral response of the voltage that are largely employed in the surface photovoltage technique are shown to be special cases that approximate the internal quantum efficiency. A more sophisticated model of the internal quantum efficiency, the model of Isenberg, and a model that allows the analysis of the internal quantum efficiency of rear-illuminated devices have been adapted to the spectral response of the voltage. This paves the way to analyze solar cells, Schottky devices, or chemically treated silicon wafers independently of the light intensity and using front or rear illumination. The models have been validated by comparing the analysis of the spectral response of the short-circuit current and the open-circuit voltage with computer simulations for a wide range of solar cells. The model of Isenberg has been found to give in general the best prediction of the recombination parameters for both the spectral photocurrent and photovoltage. The analysis of the spectral response of the voltage can often unveil the surface recombination rate where the spectral photovoltage fails to produce any output. The measurement of rear-junction cells showed that the surface recombination rate can be predicted equally well with either method.
Temperature dependence of the edge excitonic transitions of the wurtzite Cd1−x−yBexZnySe crystals
Authors: Liu Y. T. , Sitarek P. , Huang Y. S. , Firszt F. , Łęgowski S. , Męczyńska H. , Marasek A. , Paszkowicz W. , Tiong K. K.
Published: October 2005

We report a detailed investigation of the temperature dependence of the edge excitonic transitions of three Bridgman-grown wurtzite-type Cd1−x−yBexZnySe-mixed crystals using contactless electroreflectance (CER) and photoreflectance (PR) in the temperature range of 15–400 K. X-ray investigations show that the samples with beryllium (Be) content up to x=0.1 are uniform in composition and exhibit a single wurtzite phase or a wurtzite as the main phase. The transition energies of the A,B, and C excitons of Cd1−x−yBexZnySe are determined via a line-shape fit to the CER and PR spectra. The parameters that describe the temperature dependence of the interband transition energies and the broadening function of the excitonic features are evaluated and discussed.
Combined hydride and metal organic vapor-phase epitaxy of GaN on sapphire
Authors: Solomon G. S. , Miller D. J. , Ramsteiner M. , Trampert A. , Brandt O. , Ploog K. H.
Published: October 2005

We describe a method to produce GaN epitaxial layers in a single chamber where a low-temperature buffer layer is deposited using metalorganic vapor-phase epitaxy (MOVPE), followed by conventional hydride vapor-phase epitaxy (HVPE) of GaN at higher temperatures. While a typical 12μm sample is investigated here, the GaN film thickness can vary between 2 and 200μm, with HVPE growth rate ranging from 5 to 60μm∕h. Cross-sectional transmission-electron microscope images show a dense network of mixed dislocations, whose density is significantly reduced after 6μm to the high 107cm−2 range. 10 K photoluminescence shows bound exciton dominated emission associated with the A and B valence bands and phonon replicas. No yellow emission is observed. This versatile process can be extended to produce additional device layers by MOVPE.
Diffusion-controlled optical elements for optofluidics
Authors: Wolfe Daniel B. , Vezenov Dmitri V. , Mayers Brian T. , Whitesides George M. , Conroy Richard S. , Prentiss Mara G.
Published: October 2005

Diffusion at the interface between two streams of liquids with different refractive indices, flowing laminarly, creates a controllable concentration gradient and a corresponding refractive index gradient. Using flow rate to change the time over which diffusion occurs in a liquid-liquid (L2) optical waveguide, we demonstrate an optical splitter and a wavelength filter. The optical splitter comprises two parallel L2 waveguides which smoothly merge into a single L2 waveguide by diffusion. The wavelength filter comprises an optical splitter in which the two L2 waveguides contain an absorbing dye.
Defect energy levels in HfO2 high-dielectric-constant gate oxide
Authors: Xiong K. , Robertson J. , Gibson M. C. , Clark S. J.
Published: October 2005

This letter presents calculations of the energy levels of the oxygen vacancy and oxygen interstitial defects in HfO2 using density functional methods that do not need an empirical band gap correction. The levels are aligned to those of the Si channel using the known band offsets. The oxygen vacancy gives an energy level nearer the HfO2 conduction band and just above the Si gap, depending on its charge state. It is identified as the main electron trap in HfO2. The oxygen interstitial gives levels just above the oxide valence band.
Time domain analysis of coherent terahertz synchrotron radiation
Authors: Hübers H.-W. , Semenov A. , Holldack K. , Schade U. , Wüstefeld G. , Gol’tsman G.
Published: October 2005

The time structure of coherent terahertz synchrotron radiation at the electron storage ring of the Berliner Elektronensynchrotron und Speicherring Gesellschaft has been analyzed with a fast superconducting hot-electron bolometer. The emission from a single bunch of electrons was found to last ∼1500ps at frequencies around 0.4THz, which is much longer than the length of an electron bunch in the time domain (∼5ps). It is suggested that this is caused by multiple reflections at the walls of the beam line. The quadratic increase of the power with the number of electrons in the bunch as predicted for coherent synchrotron radiation and the transition from stable to bursting radiation were determined from a single storage ring fill pattern of bunches with different populations.
III-nitrides on oxygen- and zinc-face ZnO substrates
Authors: Namkoong Gon , Burnham Shawn , Lee Kyoung-Keun , Trybus Elaissa , Doolittle W. Alan , Losurdo Maria , Capezzuto Pio , Bruno Giovanni , Nemeth Bill , Nause Jeff
Published: October 2005

The characteristics of III-nitrides grown on zinc- and oxygen-face ZnO by plasma-assisted molecular beam epitaxy were investigated. The reflection high-energy electron diffraction pattern indicates formation of a cubic phase at the interface between III-nitride and both Zn- and O-face ZnO. The polarity indicates that Zn-face ZnO leads to a single polarity, while O-face ZnO forms mixed polarity of III-nitrides. Furthermore, by using a vicinal ZnO substrate, the terrace-step growth of GaN was realized with a reduction by two orders of magnitude in the dislocation-related etch pit density to ∼108cm−2, while a dislocation density of ∼1010cm−2 was obtained on the on-axis ZnO substrates.
High-performance GaN-based light-emitting diode using high-transparency Ni∕Au∕Al-doped ZnO composite contacts
Authors: Jung Sung-Pyo , Ullery Denise , Lin Chien-Hung , Lee Henry P. , Lim Jae-Hong , Hwang Dae-Kue , Kim Ja-Yeon , Yang Eun-Jeong , Park Seong-Ju
Published: October 2005

We report on a high-transparency low-resistance composite contact structure on p-GaN for light-emitting diode applications. The structure consists of a thin Ni(5nm)∕Au(5nm) layer overcoated with a sputtered Al-doped ZnO (170nm) layer. Enhancement in light emission intensity as high as 74% at 40mA and forward operating voltages in the range of 3.36–3.48V at 20mA are obtained for these devices using a two-step thermal annealing process.
Scanning thermal imaging of microelectronic circuits with a fluorescent nanoprobe
Authors: Aigouy Lionel , Tessier Gilles , Mortier Michel , Charlot Benoît
Published: October 2005

We have developed a scanning thermal imaging method that uses a fluorescent particle as a temperature sensor. The particle, which contains rare-earth ions, is glued at the end of an atomic force microscope tip and allows the determination of the temperature of its surrounding medium. The measurement is performed by comparing the relative integrated intensity of two fluorescence lines that have a well-defined temperature dependence. As an example of application, we show the temperature map on an operating complementary metal-oxide-semiconductor integrated circuit.
Modal response and frequency shift of the cantilever in a noncontact atomic force microscope
Authors: Wang Wei L. , Hu S. Jack
Published: October 2005

The force-sensing cantilever in a noncontact atomic force microscope is a continuous system with infinite number of eigenmodes. Although the frequently used point mass model was found sufficient in many cases, its conditions for validity and the insights on how higher eigen-modes could affect the selection of operation parameters were not established. In this letter, we formulate the cantilever motion using modal response analysis, a powerful means enabling an efficient numerical solution and a first order analytical solution. The origins and impacts of the higher eigenfrequency oscillation are then investigated, which sheds lights on achieving optimal imaging conditions.
Enhancement of spontaneous polarization in lead zirconate titanate thin films by Dy3+ substitution
Authors: Nakaki Hiroshi , Uchida Hiroshi , Koda Seiichiro , Okamoto Shoji , Funakubo Hiroshi , Nishida Ken , Katoda Takashi , Saito Keisuke
Published: October 2005

Spontaneous polarization can be enhanced by increasing the crystal anisotropy of tetragonal Pb(Zr,Ti)O3 [PZT] lattice by Zr and Ti-site substitution with Dy3+ cations. Spontaneous polarization (Ps) in epitaxial film of 2% Dy3+-substituted tetragonal Pb(Zr0.40Ti0.60)O3 [Dy–PZT] was compared with that of nonsubstituted Pb(Zr0.40Ti0.60)O3 [PZT] to investigate intrinsic contribution of the Dy3+ substituion to the Ps improvement. Epitaxial thin films of PZT and Dy–PZT with (111) orientations were grown on (111)cSrRuO3∕∕(111)Pt∕∕(100)YSZ∕∕(100)Si substrates by chemical solution deposition. The saturated polarization values of PZT and Dy-PZT films with (111) orientation were 41 and 48μC∕cm2, respectively. The estimated Ps values of PZT and Dy–PZT films from the saturation polarization values were 71 and 84μC∕cm2, respectively. The Ps value of this PZT was in good agreement with previous reports. The increase in Ps of the epitaxial Dy3+-substituted PZT film is attributed to the enhancement of the crystal anisotropy, i.e., tetragonality, of the tetragonal PZT lattice. This shows that the enhancement of the ferroelectricity of the tetragonal PZT films can be achieved by ion substitution, just as it can in Bi4Ti3O12-based film.
Mechanisms of arsenic segregation to the Ni2Si∕SiO2 interface during Ni2Si formation
Authors: Pawlak M. A. , Janssens T. , Lauwers A. , Vantomme A. , Vandervorst W. , Maex K. , Kittl J. A.
Published: October 2005

We have investigated the mechanisms of As redistribution during Ni2Si formation on polycrystalline Si∕SiO2 and amorphous Si∕SiO2 stacks on (100) Si by secondary ion mass spectroscopy measurements. We found a significant impact of the Si crystallinity and pre-silicidation thermal treatments on the dopant redistribution. There is a significantly higher dose of As accumulated in the vicinity of SiO2 after full Ni2Si silicidation on poly-Si (∼51%) than on amorphous-Si (∼13%). We demonstrate that the As redistribution during Ni2Si formation on amorphous silicon is dominated by snowplow of As in front of the growing silicide. In contrast, when Ni2Si is formed on recrystallized poly-silicon there are three segregation mechanisms: (1) thermal diffusion during high temperature recrystallization annealing (∼17%), (2) snowplow during silicidation (∼13%), not dependent on the substrate crystallinity and (3) diffusion along poly-Si grain boundaries during silicidation (∼22%).
Electronic structure and optoelectronic properties of strained InAsSb∕GaSb multiple quantum wells
Authors: Koprucki Thomas , Baro Michael , Bandelow Uwe , Tien Tran Q. , Weik Fritz , Tomm Jens W. , Grau Markus , Amann Markus-Christian
Published: October 2005

A study of the optical properties of a set of InAsxSb1−x∕Al0.15In0.85As0.77Sb0.23∕GaSb multiple quantum wells (0.82<x<0.92) with built-in strains in the −0.62% to +0.05% range is presented. The energy of the lowest quantum-confined optical transition is calculated by k∙p perturbation theory and experimentally determined by absorption measurements. Stokes shifts of photoluminescence, photocurrent, and of the emission from light-emitting devices against the absorption edge of the quantum well are quantified. The impact of the decreasing carrier confinement in the InAsxSb1−x quantum-well system with increasing mole fraction is analyzed theoretically, and experimentally demonstrated by photoluminescence measurements. Our results allow for the improvement of optoelectronic devices, in particular for tailoring emission spectra of light-emitting diodes.
Why Do Countries Privatize?
Authors: Megginson William Leon
Published: October 2005

This chapter begins by framing the theoretical debate about the legitimacy and efficiency of state ownership of business enterprises, and then examines the empirical evidence for and against state ownership. Since the evidence overwhelmingly indicates that state ownership is less efficient than private ownership in most real industrial settings, the reform of state-owned enterprises (SOEs) by measures short of privatization, such as exposing state enterprises to competition or imposing hard budget constraints is assessed. While some economic reforms can be effective in their own right, the question of whether these reforms would be more effective if coupled with a shift to private ownership remains unanswered. Thus, many countries have decided to launch large-scale privatization programs. The fiscal and macroeconomic impact of these programs on the public finances of divesting countries are examined.
How Do Countries Privatize?
Authors: Megginson William Leon
Published: October 2005

This chapter examines the practical aspects of privatizing state-owned enterprises (SOEs). It identifies the key issues that governments must confront in determining which SOEs to divest, and then describes the steps involved in commercializing and preparing a state-owned enterprise for privatization. Governments wishing to privatize one or more state enterprises must follow a fairly standardized process of first preparing the company for sale, then deciding on the optimal method of sale and the offering price, and finally actually selling the firm to private investors. Each step in this process has its own challenges and hazards, and is almost always steeped in controversy.
Empirical Evidence on Privatization's Effectiveness in Nontransition Economies
Authors: Megginson William Leon
Published: October 2005

This chapter examines the impact of privatization on nontransition economies by surveying existing studies on privatization’s economic effectiveness. These studies employ many different empirical methodologies, cover many different regions and time periods, and vary greatly with respect to the type and quality of data employed. The chapter considers studies that examine how privatization impacts the financial and operating performance of divested firms by comparing the pre- versus post-privatization values of several accounting and real output measures. The 87 studies from nontransition economies offer at least limited support for the proposition that privatization is associated with improvements in the operating and financial performance of divested firms. Most offer strong support for this proposition, and only a handful document outright performance declines after privatization. Nearly all studies that examine post-privatization changes in output, efficiency, profitability, capital investment spending, and leverage report significant increases in the first four measures and significant declines in leverage.
Empirical Evidence on Privatization in Transition Economies
Authors: Megginson William Leon
Published: October 2005

This chapter examines the impact of privatization on transition economies. It looks at how the 26 countries that emerged from the former Soviet bloc adapted to the new era of political freedom and market economics that rose after 1989, and the privatization experience of China. All 26 countries that emerged from the Soviet bloc have begun the political and economic process of transition, but the process has been painful and incomplete. In contrast, China’s transition experience has been immensely successful. Over the past quarter-century, China has enjoyed rapid and almost uninterrupted economic growth, and has attracted more foreign direct investment than any country in the world except the United States.
The Structure and Investment Performance of Privatization Share Offerings
Authors: Megginson William Leon
Published: October 2005

This chapter examines the structure and investment performance of share issue privatizations (SIPs). SIPs differ from private-sector share issues in almost all respects, except that both use the same financial instrument. SIPs were the first truly large share offerings of any type in most countries, so privatizations effectively inaugurated those nations’ investment banking industries. Even in the handful of countries (Britain, Japan, Canada, the United States, and a few continental European countries) where significant share offerings were already established, SIPs transformed the size and efficiency of both that country’s investment banking industry and its stock market.
Privatization's Impact on Financial Market Development
Authors: Megginson William Leon
Published: October 2005

This chapter examines the impact of share issue privatizations (SIPs) on the growth of world capital markets, especially stock markets. It also studies privatization’s impact on the pattern of share ownership by individuals and institutional investors. It begins by documenting the increasing importance of capital markets and the declining role of commercial banks in corporate financial systems around the world. It shows that privatization programs, particularly those involving public share offerings, have had a dramatic impact both on the development of non-US stock markets and the participation of individual and institutional investors in those markets. The components of a nation’s corporate governance system are described, and how privatization programs can promote the development of an effective corporate governance system is discussed.
Privatization Industry Studies
Authors: Megginson William Leon
Published: October 2005

This chapter begins with an overview of how state ownership of telecommunications evolved during the 20th century. It details the key regulatory issues governments face when privatizing its telecom provider, and offers policy recommendations based on the experiences of countries that have privatized their telecommunications service providers. The two basic methods used to divest telecom ownership stakes and empirical evidence on the effectiveness of telecom privatization are discussed.
Privatization Industry Studies
Authors: Megginson William Leon
Published: October 2005

This chapter examines the privatization histories and regulatory regimes adopted for oil and companies, electric utilities, and national airlines. The first section details the history of oil and gas sales by governments, and presents estimates of the value of retained government stakes and the value of national oil companies that remain wholly state-owned. The second section provides a similar treatment of electric utility privatizations, though this section also delves much more deeply into the regulatory challenges that arise naturally when governments decide to sell off operating companies in their electric service industries. The final section describes the history of airline privatizations and assesses the current and likely future prospects for further sales of state-owned airlines.
Saving Souls, Serving Society
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

The political controversy surrounding the role of religion in public life calls for more objective attention to the faith factor in social activism. What does it mean for a community-serving program to be “faith-based”? How do churches and other religious organizations express their religious identity or convey a religious message in the context of social services? Drawing on case studies of fifteen Philadelphia-area Protestant churches with active community outreach, Saving Souls, Serving Society introduces a new vocabulary for describing the religious components and spiritual meanings embedded in social action, and provides a typology of faith-based organizations and programs. This analysis yields a framework for Protestant mission orientations that makes room for the diverse ways that churches interrelate spiritual witness and social compassion. In particular, the debate over faith-based initiatives has highlighted a small but growing segment of churches committed to both saving souls and serving society. The book illuminates the public engagement of these “;conversionist” churches, exploring how they navigate the tension between their spiritual mission and the constraints on evangelism in the context of social services. The closing chapters explicate the potential contribution of religious dynamics to social outcomes, assess the relationship between mission orientations and social capital, present recommendations for research on faith-based social services, and draw implications for a constructive approach to church-state relations. Openness to a fresh perspective can equip policy makers, scholars and practitioners to respond wisely to the evolving complexities of the religious contours of social ministry.
Introduction
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

Religious entities play a vital though limited role in our social safety net. The majority of congregations engage in community-serving activities, though their commitments tend to be shallow. Four currents in the broader political and social setting have particular implications for understanding faith-based social services: devolution, faith-based initiatives, changing norms for religion in public life, and ambivalence toward evangelism. Shifting patterns in church-state relations have generated both opportunities and uncertainties. This dynamic context invites a fresh conceptual framework for interpreting churches' public engagement. In particular, new language is needed to describe the “faith factor” that has meaning outside of the religious community, but does not reduce faith to a product of other social variables
The Churches and Their Ministries
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

This chapter introduces fifteen diverse Protestant churches noted for their community outreach, in the context of their Philadelphia religious ecology. The 237 programs sponsored by these case study churches are analyzed based on definitions of the key terms “social action” and “evangelism”. Social action includes four basic categories: relief services, personal development, community development, and systemic change. While individualistic, immediate aid tends to predominate over structural approaches to social problems, the amount and type of social ministry to emerge at a given church defies easy prediction. Among the churches studied, a strong emphasis on evangelism does not necessarily preclude involvement in social concerns.
Case Studies of Faith in Action
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

This chapter highlights eight of the case study churches selected from the Philadelphia area. The narratives focus on how these churches define their mission, particularly in terms of the relationship between social action and evangelism, and put their theological beliefs into action through community outreach. As a complement to their stories, the chapter presents survey data on church members' motivations and beliefs relevant to outreach, as well as their reported rates of actual practices of evangelism, informal acts of compassion and civic involvement.
Perceptions of Spiritual Meaning in Faith-Based Social Action
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

Acts of compassion are not unique to people of faith, but faith makes these actions uniquely meaningful. Even ostensibly secular good works may be saturated with personal religious significance. The ascription of spiritual meaning to social action is part of the larger religious enterprise that Peter Berger refers to as “world-building”. Among Protestant Christians, these meanings fall into four domains: religion mandates social action; divine agency empowers social change; social activism reflects or enhances one's inner spiritual state; and social ministry is intended to enhance the spiritual life of others. It is the selection and combination of these four modalities—dutiful, empowered, devotional, and evangelistic—that gives a faith-based social service program its distinctive character.
Religious Elements of Faith-Based Social Programs
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

Some faith-based social service programs incorporate specifically religious content, intended to expose beneficiaries to religious resources, messages, or activities. Religious program elements include religious references in program self-descriptions, religious objects in the program environment, invitations to religious activities, prayer, use of sacred texts, worship, sharing of personal testimonies, religious teachings, and invitations to a personal faith commitment (proselytizing). Seven variables further describe the style or format of these religious elements, particularly whether they are mandatory, and how they are structured into the program methodology. From this follows five general strategies for incorporating a religious dimension into social services: implicit, invitational, relational, integrated-optional, and mandatory.
A Typology of Faith-Based Organizations and Programs
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

The term “faith-based organizations” is inadequate because no clear definition exists of what it means to be “faith-based”. This chapter proposes an inductively derived typology to capture the religious characteristics of social service organizations and programs. The analysis focuses on the tangible, overt ways that religion may be manifest in a nonprofit entity, yielding six types: faith-permeated, faith-centered, faith-affiliated, faith-background, faith-secular partnership, and secular. The model is multidimensional, recognizing that the religious characteristics of an institution may differ from the specific programs it operates. Examples are drawn from the Philadelphia area to illustrate each type of organization and program.
Defining Mission Orientations
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

A mission orientation frames a moral order for a congregation's activity and identity. This chapter focuses on the ways that churches organize the spiritual and social dimensions of their public mission. In place of the traditional dichotomy between social activism and evangelism, a more nuanced set of orientations classifies churches as dominant social action, dual-focus, holistic, dominant evangelism, and inward-focused. This spectrum of types indicates that the religious impulses to serve and to save are not always polarized drives; rather, churches interrelate these two imperatives in their community outreach in a range of adaptable, and sometimes rather sophisticated, ways.
Influences on Congregational Mission
Authors: Unruh Heidi Rolland , Sider Ronald J.
Published: October 2005

A church's mission orientation may be shaped by a mosaic of influences, including culture, theology, structures of authority, resources, and social context. Congregations do not invent their mission orientation afresh; they draw on established ethnic, denominational and historical scripts of how to conduct outreach, while adding their own innovations. A brief history of the relationship between evangelism and social action, focusing on Anglo American evangelicalism, highlights the legacy of the split between religious conservatives and advocates of the social gospel. This divide does not represent an unchangeable given, but a historic phenomenon that is being actively renegotiated, giving rise to new ministry patterns.