bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation by photothermal microscopy of increased silica absorption in laser damage induced by gold nanoparticles
Authors: Bonneau F. , Combis P. , Rullier J. L. , Commandré M. , During A. , Natoli J. Y. , Pellin M. J. , Savina M. R. , Cottancin E. , Pellarin M.
Published: November 2003

In order to understand laser-induced damage in glass, we subjected engineered SiO2 thin films containing sub-micron gold inclusions to high fluences, and observed the results using several means of analysis. We found decoupling in time between the emission of gold and that of silicon with samples containing gold spheres of diameter 3 nm. We have analyzed the changes in the silica optical absorption at 1064 nm, using photothermal deflection microscopy. We find, upon exceeding a sharp fluence threshold, a thousand-fold increase in absorption of the silica matrix around the inclusion. We conclude that ions from the inclusion permeate the surrounding silica, and form a highly absorbent mixture.
Small angle x-ray scattering for sub-100 nm pattern characterization
Authors: Jones Ronald L. , Hu Tengjiao , Lin Eric K. , Wu Wen-Li , Kolb Rainer , Casa Diego M. , Bolton Patrick J. , Barclay George G.
Published: November 2003

Characterization of sub-100 nm photolithographic patterns with nanometer scale resolution is demonstrated using small angle x-ray scattering. The transmission scattering geometry employed potentially enables high throughput measurements for future technology nodes of the semiconductor industry, organic and inorganic nanoscale devices, and three-dimensional structures. The method is demonstrated through the characterization of a series of polymer photoresist gratings using a synchrotron x-ray source. Quantities, such as periodicity and line width, are extracted using minimal modeling. Additional quantities and the potential of a laboratory-based x-ray system are briefly discussed.
Controlled transformation of paramagnetism to room-temperature ferromagnetism in cobalt-doped titanium dioxide
Authors: Manivannan A. , Glaspell G. , Seehra M. S.
Published: November 2003

Samples of Co0.1Ti0.9O2−δ (anatase) prepared by the sol–gel technique are found to be paramagnetic at room temperature, with the magnetic susceptibility following Curie–Weiss law in the investigated range of 2–370 K. However, transformation from paramagnetism to room-temperature ferromagnetism (RTFM) is observed by hydrogenation of the sample at 573 K. The increase in the hydrogenation time from 1 to 6 h increases the remanance, and the Curie temperature ≃470 K is determined by extrapolation. X-ray photoelectron spectroscopy and transmission electron microscopy of the hydrogenated samples failed to detect Co nanoparticles, suggesting that the observed RTFM in the hydrogenated samples may be intrinsic.
Fourier transformed photoreflectance characterization of interface electric fields in GaAs/GaInP heterojunction bipolar transistor wafers
Authors: Kita T. , Kakutani T. , Wada O. , Tsuchiya T. , Sahara M. , Sakaguchi H.
Published: November 2003

We performed Fourier transformed photoreflectance (PR) spectroscopy on GaAs/Ga0.5In0.5P heterojunction bipolar transistor wafers. The use of Fourier transformation of the PR spectrum resolves the signals coming from the emitter–base and base–collector interfaces. The evaluated interface electric fields were compared with the capacitance obtained from capacitance–voltage measurements. The result for the base–collector interface is consistent with the Poisson equation. On the other hand, the atomic ordering in the Ga0.5In0.5P emitter plays an important role in determining the characteristics of the emitter–base interface.
Study of the electronic properties of some ytterbium filled skutterudites by magnetic susceptibility and x-ray absorption and tin-119 Mössbauer spectroscopy
Authors: Grandjean Fernande , Long Gary J. , Mahieu Bernard , Yang J. , Meisner G. P. , Morelli D. T.
Published: November 2003

Magnetic susceptibility, ytterbium LIII-edge x-ray absorption and tin-119 Mössbauer spectral measurements have been carried out to probe the electronic structure of ytterbium and tin in the filled or partially filled skutterudite compounds, YbyCo4Sb12−xSnx, over a range of x and y values. The ytterbium valence obtained from the magnetic susceptibility and ytterbium LIII-edge x-ray absorption measurements is in excellent agreement and clearly reveals an evolution from intermediate valence ytterbium for x=0 to nearly divalent ytterbium for x=0.8. This evolution parallels an increase in the unit cell volume and hence in the ytterbium site volume available as the tin content increases. The tin-119 Mössbauer spectral hyperfine parameters indicate, without question, that tin substitutes on the antimony sublattice of the skutterudite structure. Further, the tin electronic configuration is both very similar to that of the antimony in the structure and insensitive to the ytterbium content, y.
Surface termination during GaN growth by metalorganic vapor phase epitaxy determined by ellipsometry
Authors: Cobet C. , Schmidtling T. , Drago M. , Wollschläger N. , Esser N. , Richter W. , Feenstra R. M. , Kampen T. U.
Published: November 2003

Spectroscopic ellipsometry is used to study GaN films during growth by metalorganic vapor phase epitaxy (MOVPE) in correlation to well known results of plasma-assisted molecular beam epitaxy (PAMBE). Results for the PAMBE reveal clear differences between growth under Ga-rich and N-rich conditions, which are attributed to the presence of a Ga bilayer on the surface (also seen with low energy electron diffraction) in the Ga-rich case. Results for MOVPE surfaces during growth or for surfaces which are stabilized under NH3 are very similar to the N-rich PAMBE result. It is concluded that under normal growth conditions in MOVPE in contrast to PAMBE the surface is not terminated by a Ga bilayer.
Current amplification in high-temperature superconductor current injection three-terminal devices
Authors: Morán O. , Hott R. , Schneider R. , Wühl H. , Halbritter J.
Published: November 2003

Current injection into superconducting microbridges has been studied for state-of-the-art YBa2Cu3O7−x/SrTiO3/Au (YBCO/STO/Au) planar heterostructures based on c-axis oriented YBCO layers. By injecting a gate current Ig into the YBCO channel of these three-terminal devices the critical current Ic could be reduced up to a gain factor G≡−dIc/dIg∼5 at 77 K. G is found to be roughly proportional to the superconducting quality of the samples as expressed by the critical current density Jc of the YBCO channel. At least for our high-quality samples, this Ic suppression is shown to be mainly due to the perturbation of the electronic superconductive equilibrium state by quasiparticles associated with the injection of the gate current. However, this basic mechanism for the current-injection-based transistor principle was in our experiments always accompanied by substantial parasitic effects, such as current summation and Joule heating due to electric power dissipation in the ultrathin STO barrier. This reduces the efficiency of the transistor mechanism and thus the hopes for THz operation of such devices.
Magnetic force gradient mapping
Authors: Schäffer Tilman E. , Radmacher Manfred , Proksch Roger
Published: November 2003

Motivated by the difficulty of obtaining quantitative micromagnetic results using current magnetic force microscope imaging techniques, we have employed an imaging mode where the oscillation amplitude of the tip was recorded versus the tip–sample separation as the tip was raster scanned over a magneto-optic sample. The mechanical response of the cantilever depends on the magnetic, but also on topographic, interferometric and nonmagnetic dissipative interactions between the tip and the sample. We separated the magnetic signal from the other interactions and analyzed it in terms of a refined theory of magnetic force microscope response. The extracted magnetic signal, which we refer to as a force gradient map, showed some features not apparent in conventional magnetic force microscope images and was well fit by a simple micromagnetic model of the magneto-optic sample.
Efficient third-harmonic generation in a thin nanocrystalline film of ZnO
Authors: Petrov G. I. , Shcheslavskiy V. , Yakovlev V. V. , Ozerov I. , Chelnokov E. , Marine W.
Published: November 2003

Nonlinear optical conversion is studied in thin films of wide-bandgap materials. Very high conversion efficiency to the third-harmonic radiation is achieved for an unamplified femtosecond Cr4+:forsterite laser in a submicron-thick film of a nanocrystalline ZnO pulsed-laser-deposited on a fused silica substrate.
Remote identification of protrusions and dents on surfaces by terahertz reflectometry with spatial beam filtering and out-of-focus detection
Authors: Hasegawa Noboru , Löffler Torsten , Thomson Mark , Roskos Hartmut G.
Published: November 2003

We propose two terahertz reflectometry modalities that are optimized to be sensitive to the curvature of surface features. The first is a dark-field technique that allows the detection of protrusions and dents on surfaces with high sensitivity. It cannot distinguish, however, between convex and concave shapes. This becomes possible with the second technique, which combines out-of-focus imaging with suitable beam filtering. Both methods may be of interest for surface inspection in fabrication environments; for example, for online monitoring during metal processing.
All-organic thin-film transistors patterned by means of selective electropolymerization
Authors: Becker E. , Parashkov R. , Ginev G. , Schneider D. , Hartmann S. , Brunetti F. , Dobbertin T. , Metzdorf D. , Riedl T. , Johannes H.-H. , Kowalsky W.
Published: November 2003

We have fabricated fully patterned all-organic thin-film transistors on polyimide substrates using selectively electropolymerized poly (3,4-ethylenedioxythiophene) doped with poly (styrene sulfonate) (PEDOT:PSS) for the source and drain contacts, PEDOT:PSS Baytron P dispersion for the gate electrodes, poly (4-vinyl phenol) or polyvinyl alcohol for the gate dielectric layers, and pentacene or poly (3-butylthiophene) for the organic active layers. We have built top-gate structures with gates printed on top of the gate dielectric layer. Carrier mobilities as large as 0.01 cm2/V s were measured. Functional all-organic transistors have been realized using a simple and potentially inexpensive technology that does not depend on photolithographical processes and that allows the preparation of feature sizes on the micrometer scale.
Noncontact density measurements of tantalum and rhenium in the liquid and undercooled states
Authors: Paradis Paul-François , Ishikawa Takehiko , Yoda Shinichi
Published: November 2003

Electrostatic levitation together with multibeam heating and ultraviolet imaging overcame contamination, imaging, and sample position stability problems associated with handling of liquid tantalum and rhenium. Here, the density [ρ(T)] of these metals is reported in the superheated and undercooled states. Over the 2760–3580 K interval, the density of tantalum was measured as ρ(T)=1.50×104−0.41(T−Tm) kg m−3, where the melting temperature Tm, was 3290 K. For rhenium, the density was determined (2700–3810 K) as ρ(T)=1.84×104−0.91(T−Tm), with Tm=3453 K. From these data, respective volume expansion coefficients of 2.7×10−5 and 4.9×10−5 K−1 were calculated. At Tm, the data agree well with the literature values.
White-light supercontinuum interference of self-focused filaments in water
Authors: Cook K. , Kar A. K. , Lamb R. A.
Published: November 2003

The generation of a horizontal array of stable white-light continuum (WLC) filaments in water is observed using a cylindrical planoconvex lens. The widths of these filaments are measured both directly by imaging and indirectly through analysis of filament interference patterns. The stable interference pattern created by a filament pair is similar to that due to a pair of Young’s slits, and implies a constant phase relationship between the WLC generated by each filament. The experimental results agree well with theoretical predictions for the number of fringes and the fringe spacing.
Piezoelectric anisotropy–phase transition relations in perovskite single crystals
Authors: Budimir Marko , Damjanovic Dragan , Setter Nava
Published: November 2003

The orientation dependence of the longitudinal piezoelectric coefficient, d33*, is investigated as a function of temperature in BaTiO3 and PbTiO3 crystals using the Landau–Ginsburg–Devonshire theory. We show that a presence of the ferroelectric–ferroelectric phase transitions in BaTiO3 leads to enhanced d33* along nonpolar directions. The reason for this is that in the vicinity of a phase transition temperature at which a polarization vector changes its direction (tetragonal–orthorhombic/monoclinic, orthorhombic/monoclinic–rhombohedral), the shear piezoelectric coefficients become high. It is shown for all ferroelectric phases of BaTiO3 that the shear stress deforms the crystal cell and changes the polarization direction in a similar way as the corresponding temperature-induced phase transition. The influence of the piezoelectric shear effect on the anisotropy of d33* is particularly pronounced in the orthorhombic/monoclinic phase where the piezoelectric shear coefficients are determined by the presence of both the high-temperature tetragonal and the low-temperature rhombohedral phases. In PbTiO3, which does not exhibit ferroelectric–ferroelectric phase transitions, the shear piezoelectric effect is weak and d33* has its maximum along the polar axis at all temperatures. These results can be generalized to include phase transitions induced by electric-field and composition variations and are valid for all perovskite materials, including complex relaxor–ferroelectric perovskites that have recently attracted attention for their exceptionally large piezoelectric properties.
Enhanced recombination tunneling in GaAs pn junctions containing low-temperature-grown-GaAs and ErAs layers
Authors: Pohl P. , Renner F. H. , Eckardt M. , Schwanhäußer A. , Friedrich A. , Yüksekdag Ö. , Malzer S. , Döhler G. H. , Kiesel P. , Driscoll D. , Hanson M. , Gossard A. C.
Published: November 2003

We report electrical conductivity studies of highly-doped GaAs pn diodes containing a strongly n-doped low-temperature-grown (LT)–GaAs layer and pn junctions containing an approximately one monolayer thick ErAs layer. At room temperature, current densities of 1 kA/cm2 for the n-LT–GaAs samples and 6 kA/cm2 for the ErAs samples at 1 V forward bias have been measured. The I–V characteristics under forward bias for the n-LT–GaAs and ErAs samples exhibit significantly different behavior. At low temperatures, the n-LT–GaAs samples reveal a shoulder in the I–V characteristics, which can be explained by a model taking into account tunneling of carriers into LT midgap states. A similar model was able to explain the current transport in the ErAs diodes as tunneling of carriers into metallic regions inside the pn junction.
Fast switching dual-frequency liquid crystal optical retarder, driven by an amplitude and frequency modulated voltage
Authors: Golovin Andrii B. , Shiyanovskii Sergij V. , Lavrentovich Oleg D.
Published: November 2003

We demonstrate theoretically and experimentally a fast-switching nematic optical retarder capable to switch a few microns of optical retardation in less than 1 ms. For example, a nematic cell of thickness 14.5 μm switches 0.3 μm of retardation within 0.15 ms and 2.5 μm within 0.5 ms for single passage of beam. The corresponding figure of merit is two orders of magnitude higher than the one known for the best nematic materials synthesized so far. The fit is achieved by employing a dual-frequency nematic liquid crystal in high-pretilt angle cells and a special addressing scheme that features amplitude and frequency modulated voltage. The scheme can be used in spatial light modulators, retarders, beam deflectors, polarization rotator, and displays.
Inductive measurements of third-harmonic voltage and critical current density in bulk superconductors
Authors: Mawatari Yasunori , Yamasaki Hirofumi , Nakagawa Yoshihiko
Published: November 2003

We propose an inductive method to measure critical current density Jc in bulk superconductors. In this method, an ac magnetic field is generated by a drive current I0 flowing in a small coil mounted just above the flat surface of superconductors, and the third-harmonic voltage V3 induced in the coil is detected. We present theoretical calculation based on the critical state model for the ac response of bulk superconductors, and we show that the third-harmonic voltage detected in the inductive measurements is expressed as V3=G3ωI02/Jc, where ω/2π is the frequency of the drive current, and G3 is a factor determined by the configuration of the coil. We measured the I0–V3 curves of a melt-textured YBa2Cu3O7−δ bulk sample, and evaluated the Jc by using the theoretical results.
Ferroelectric Pb(Zr0.52Ti0.48)/SiC field-effect transistor
Authors: Koo Sang-Mo , Khartsev Sergey , Zetterling Carl-Mikael , Grishin Alex , Östling Mikael
Published: November 2003

Nonvolatile operation of ferroelectric gate field-effect transistors in silicon carbide (SiC) is demonstrated. Depletion mode transistors have been realized by forming a Pb(Zr0.52Ti0.48)O3/Al2O3 gate stack on n-type epitaxial channel layer and p-type substrate of 4H-SiC. A memory window, as wide as 5 V, has been observed in the drain current and the ferroelectric gate voltage transfer characteristics. The transistor showed memory effect from room temperature up to 200 °C, whereas stable transistor operation was observed up to 300 °C. The retention of remnant polarization was preserved after 2×104 s at 150 °C with no bias on the gate.
Ferroelastic properties of oriented TbxDy1−xFe2 polycrystals
Authors: Feng Xue , Fang Dai-Ning , Hwang Keh-Chih , Wu Guang-Heng
Published: November 2003

It is important to study the effect of the mechanical stress on magnetic properties of the TbxDy1−xFe2 alloys used in advanced actuator systems. In this investigation, compressive strain and demagnetization were measured under coupled magnetomechanical loading. The nonlinear behavior of the strain and demagnetization can clearly be explained by magnetic-domain switching process. The coercive stress and Young’s modulus can be obtained from the measured stress–strain curves and demagnetization curves.
Optical properties of Pb(Zr,Ti)O3 thin films on sapphire prepared by metalorganic decomposition process
Authors: Kao Chien-Kang , Tsai Chuen-Horng , Lin I-Nan
Published: November 2003

Pb(Zr 0.52 Ti 0.48 ) O 3 (PZT) thin films were synthesized on a sapphire substrate for application as planar optical waveguide devices using a metalorganic decomposition (MOD) process. Pyrochlore phase, which always forms preferentially when the PZT thin films (∼200 nm) are deposited on a sapphire substrate directly, has been effectively suppressed by using a SrTiO3 (STO) film (∼190 nm) as a buffer layer. The PZT/sapphire thin films have a significantly larger refractive index than the STO/sapphire ones: nPZT=2.2012 and nSTO=2.0639 (at 632.8 nm) by prism coupling measurement and nPZT′=2.215 and nSTO′=2.084 (at 632.8 nm) by optical transmission spectroscopic measurement. The STO layer cannot only serve as buffer layer for enhancing the crystallization kinetics of the subsequently deposited PZT thin films, but can also serve as cladding layer in a ridge-type planar waveguide, which uses PZT thin film as core materials.
A micro methanol fuel cell operating at near room temperature
Authors: Yen T. J. , Fang N. , Zhang X. , Lu G. Q. , Wang C. Y.
Published: November 2003

We present a bipolar micro direct methanol fuel cell (μDMFC) with high-power density and simple device structure. A proton exchange membrane-electrode assembly was integrated in a Si-based μDMFC with micro channels 750 μm wide and 400 μm deep, fabricated using silicon micromachining. The μDMFC has been characterized at near room temperature, showing a maximum power density of 47.2 mW/cm2 when 1 M methanol was fed at 60 °C. The cell voltage dependence on the current density agrees well with the modified Tafel model, in which regimes of kinetic polarization and ohmic polarization are observed without significant presence of the concentration polarization.
Formation of silicides in a cavity applicator microwave system
Authors: Thompson D. C. , Kim H. C. , Alford T. L. , Mayer J. W.
Published: November 2003

Metal silicides of nickel and cobalt are formed in a cavity applicator microwave system with a magnetron power of 1200 W and a frequency of 2.45 GHz. X-ray diffraction, Rutherford backscattering spectrometry, and four-point-probe measurements are used to identify the silicide phase present and layer thicknesses. Additional processing confirmed that the products attained from heating by microwaves do not differ appreciably from those attained in heating by thermal processes. Materials properties are used to explain microwave power absorption and demonstrate how to tailor a robust process in which thin film reactions can be attained and specific products isolated.
Thermal annealing effects on an InGaN film with an average indium mole fraction of 0.31
Authors: Feng Shih-Wei , Lin En-Chiang , Tang Tsung-Yi , Cheng Yung-Chen , Wang Hsiang-Chen , Yang C. C. , Ma Kung-Jen , Shen Ching-Hsing , Chen L. C. , Kim K. H. , Lin J. Y. , Jiang H. X.
Published: November 2003

We compared the optical and material properties of an InGaN thin film with an average indium content at 0.31 between as-grown and postgrowth thermally annealed conditions. The major part of the photoluminescence spectrum was shifted from the original yellow band into the blue range upon thermal annealing. Cathodoluminescence (CL) spectra showed that the spectral shift occurred essentially in a shallow layer of the InGaN film. The deeper layer in the as-grown sample contributed blue emission because it had been thermally annealed during the growth of the shallow layer. The spectral change was attributed to the general trends of cluster size reduction and possibly quantum-confined Stark effect relaxation upon thermal annealing. The attribution was supported by the observations in the CL, x-ray diffraction, and high-resolution transmission electron microscopy results.
High mobility oxides: Engineered structures to overcome intrinsic performance limitations of transparent conducting oxides
Authors: Robbins Joshua J. , Wolden Colin A.
Published: November 2003

After a decade of intensive materials discovery and optimization, no single transparent conducting oxide has exceeded the intrinsic electrical performance limits suggested in 1992. High mobility oxide (HMO) structures are proposed as an alternative design that can surpass single material performance. Based on oxides with different electron affinities, direct simulations indicate that HMOs could obtain conductivity values >4.2×104 S/cm. The conductivity is very sensitive to the quantum well thickness, and the individual layers must be <5 nm thick in order for HMO structures to surpass the intrinsic limits of a single material. Thus, a high degree of control over crystal structure and interface quality would be required to realize these performance levels.
Demonstration of planar tunneling through solid inert gas barriers
Authors: Adams L. L. A. , Christiansen Cathryn , Goldman A. M.
Published: November 2003

Metal–insulator–metal junctions were fabricated with insulating barriers of solid Xe. The current–voltage characteristics of these junctions when unshorted were consistent with tunneling theory. The fabrication of junctions with solid inert gas solid insulating barriers may make it possible to carry out tunneling spectroscopy of complex compounds that are susceptible to chemical and mechanical damage.
Fabrication of homostructural ZnO p–n junctions and ohmic contacts to arsenic-doped p-type ZnO
Authors: Ryu Y. R. , Lee T. S. , Leem J. H. , White H. W.
Published: November 2003

We report fabrication of homostructural ZnO p–n junctions that contain arsenic (As)-doped ZnO (ZnO:As) and intrinsic n-type ZnO layers. We also describe the metallization process for forming ohmic contacts to p-type ZnO. ZnO films were synthesized on n-type SiC substrates by hybrid beam deposition. Ni/Au metal contacts show linear I–V characteristics indicative of ohmic behavior, while other metal contacts (e.g., In/Au and Ti/Au) show nonlinear characteristics with rectification that reveal the presence of Schottky barriers. The characteristics for p–n junctions composed of ZnO layers are confirmed by I–V measurements.
Synthesis, optical, and magnetic properties of diluted magnetic semiconductor Zn1−xMnxO nanowires via vapor phase growth
Authors: Chang Y. Q. , Wang D. B. , Luo X. H. , Xu X. Y. , Chen X. H. , Li L. , Chen C. P. , Wang R. M. , Xu J. , Yu D. P.
Published: November 2003

Diluted magnetic semiconductor Zn1−xMnxO nanowires were synthesized via an in situ doping of manganese in ZnO nanowires using vapor phase growth at 500 °C. The maximum content of the manganese in the ZnO is around 13 at. %, approaching the maximum thermal equilibrium limit of Mn solubility in ZnO at the growth temperature. Structure and composition analysis revealed that the manganese was doped into the lattice structure, forming solid solution instead of precipitation. Magnetic property measurements revealed that the as-doped Zn1−xMnxO nanowires exhibit ferromagnetic behavior with Curie temperature around 37 K.
Thermal profiling for optical characterization of waveguide devices
Authors: Hudgings J. A. , Pipe K. P. , Ram R. J.
Published: November 2003

We demonstrate a thermal profiling technique for wafer-scale testing of the optical power distribution in photonic integrated circuits. Radiative cooling of the lattice of a semiconductor optical amplifier is observed in response to an optical signal; likewise, lattice heating occurs in an optically injected absorber. We develop a total energy balance model that can be used to quantify modal gain or absorption within these devices, along with longitudinal and vertical thermal impedances and heat transfer coefficients. Spatially resolved thermal profiling in conjunction with our energy balance model accurately describes the optical power distribution inside optoelectronic devices, without recourse to direct optical measurement.
Anisotropy of the magnetotransport in (Ga,Mn)As/MnAs paramagnetic-ferromagnetic hybrid structures
Authors: Ye S. , Klar P. J. , Hartmann Th. , Heimbrodt W. , Lampalzer M. , Nau S. , Torunski T. , Stolz W. , Kurz T. , Krug von Nidda H.-A. , Loidl A.
Published: November 2003

We investigated the temperature-dependent magnetoresistance of granular (Ga,Mn)As/MnAs hybrids grown on (100) GaAs in different transport geometries. The observed magnetoresistance effects are much bigger than for a corresponding (Ga,Mn)As reference sample without MnAs nanoclusters. We find that the magnetoresistance effects depend strongly on the chosen transport geometry. When the external field is perpendicular to the sample plane the effects are largest. The smallest effects occur when the external field is in the sample plane and parallel to the current. Furthermore, we have established by ferromagnetic resonance studies that the magnetic properties of the ensemble of ferromagnetic MnAs nanoclusters is similar for the magnetic field orientations studied. Therefore, the observed anisotropy of the magnetoresistance mainly reflects the difference in current path through the sample which leads to a variation of the degree of interaction between the free carriers in the matrix and nanoclusters.
Fast diffusion in ZrTiCuNiBe melts
Authors: Meyer A. , Petry W. , Koza M. , Macht M.-P.
Published: November 2003

Atomic transport in Zr41.2Ti13.8Cu12.5Ni10Be22.5 and Zr46.8Ti8.2Cu7.5Ni10Be27.5 melts has been investigated with incoherent, quasielastic neutron scattering. From the q dependence of the quasielastic signal an average self-diffusion coefficient of the incoherent scatterers Ni and Ti has been obtained. Values are on a 10−10 m2 s−1 scale. In contrast to the viscosity, the diffusion coefficient is rather independent of the alloy’s composition. Above the liquidus temperature times scales for Ni and Ti self diffusion and for viscous flow differ by up to two orders of magnitude: It appears, that the smaller atoms diffuse in a relative immobile Zr matrix.
Carbon-based printed contacts for organic thin-film transistors
Authors: Brandon Erik J. , West William , Wesseling Emily
Published: November 2003

Organic thin-film transistors (OTFTs) employing a flexible, conductive carbon particle-polymer composite material for the drain-source ohmic contacts are reported herein. The contacts can be deposited using standard stencil printing techniques and are processed at low temperature, thereby facilitating their integration with heat sensitive substrates. The carbon contacts were stencil printed on a silicon dioxide gate dielectric layer, and the poly(3-hexylthiophene) semiconductor was deposited via solution casting from toluene. The OTFTs exhibited field-effect behavior over a range of drain-source and gate voltages, similar to devices employing deposited gold contacts.
Photonic bandedge lasers in two-dimensional square-lattice photonic crystal slabs
Authors: Kwon Soon-Hong , Ryu Han-Youl , Kim Guk-Hyun , Lee Yong-Hee , Kim Sung-Bock
Published: November 2003

Square-lattice bandedge lasers are realized by room-temperature optical pumping of photonic crystal air-bridge slabs of InGaAsP quantum wells emitting at 1.5 μm. Lasing modes corresponding to the second bandedges near the X and M points are identified from their spectral positions and polarization directions. A low threshold incident pump power of less than 1 mW is achieved for the laser operating at the second bandedge near the X and M points, with only 15×15 lattice points. The measured characteristics of the bandedge lasers closely agree with the result of calculations based on the plane-wave-expansion method and the finite-difference time-domain method.
Isolated double quantum dot capacitively coupled to a single quantum dot single-electron transistor in silicon
Authors: Emiroglu Emir G. , Hasko David G. , Williams David A.
Published: November 2003

We report electron transport measurements on a single-island single-electron transistor capacitively coupled to an isolated double quantum dot at 4.2 K. The structure is fabricated through trench isolation in silicon-on-insulator. We detect single-electron polarization of the isolated double quantum dot using the single-electron transistor as a sensitive electrometer, and estimate its charging energy. We observe a large suppression of current and modulation of Coulomb blockade peak heights as a function of applied gate voltages.
Terahertz quantum cascade lasers in a magnetic field
Authors: Tamosiunas V. , Zobl R. , Ulrich J. , Unterrainer K. , Colombelli R. , Gmachl C. , West K. , Pfeiffer L. , Capasso F.
Published: November 2003

We have investigated the behavior of a terahertz quantum cascade laser in an external magnetic field. A reduction of the threshold current density and a simultaneous enhancement of the laser emission intensity are observed. Although several mechanisms can induce this effect, the suppression of nonradiative Auger-intersubband transitions through Landau quantization of the in-plane electron motion is the most probable candidate. In addition, the injection rate via resonant inter-Landau-level transfer and the waveguide properties are modulated by the field. We also observed clear shifts of the emission spectra when the external magnetic field is applied, while operating the device at constant voltage or current.
Pulsed magnetic field-induced actuation of Ni–Mn–Ga single crystals
Authors: Marioni Miguel A. , O’Handley Robert C. , Allen Samuel M.
Published: November 2003

The field-induced actuation of Ni–Mn–Ga single crystals through twin-boundary motion has been demonstrated with magnetic fieldpulses of various intensities lasting 620 μs. It is shown that the complete field-induced strain can be obtained in 250 μs, which implies the possibility of full 6% cycling of Ni–Mn–Ga at 2 kHz, for crystals having dimensions in the range of a few millimeters. The final extension increases with the peak driving force, which is not linear with the field and saturates at 7.85 kOe. An increase of the field beyond the saturation level produces no additional strain but reduces the time for field-induced detwinning.
Linear and ultrafast nonlinear optical response of Ag:Bi2O3 composite films
Authors: Zhou P. , You G. J. , Li Y. G. , Han T. , Li J. , Wang S. Y. , Chen L. Y. , Liu Y. , Qian S. X.
Published: November 2003

Silver/bismuth oxide composite thin films with Ag concentration varying from 13.2% to 59.3% were prepared by cosputtering in a multitarget magnetron sputtering system. The absorption spectra of these thin films were measured, and the absorption peaks due to surface plasmon resonance of Ag particles showed a redshift behavior with increasing Ag concentration. By using the femtosecond time-resolved optical Kerr effect technique under 800 nm wavelength, the nonlinear optical properties of these films were investigated. The Kerr signals showed an ultrafast rise, suggesting that the main physical mechanism involved in the optical nonlinearity of Ag:Bi2O3 thin films on the femtosecond scale was the pure electronic contributions. The maximum value of the third-order nonlinear optical susceptibility of Ag:Bi2O3 thin films was 4.1×10−10 esu, and occurred at a Ag concentration of about 35.7%.
Voltage-tunable, two-band mid-infrared detection based on Si/SiGe quantum-cascade injector structures
Authors: Rauter P. , Fromherz T. , Bauer G. , Diehl L. , Dehlinger G. , Sigg H. , Grützmacher D. , Schneider H.
Published: November 2003

Photocurrent spectroscopy has been performed on doped Si/SiGe valence band cascade injector structures in the mid-infrared spectral region. A large tunability of the photoresponse peak wavelength (from 5.2 to 3.2 μm) by an externally applied electric field is observed. The tunability of the photoresponse is a consequence of an electric-field-induced transfer of holes from the deepest to the shallowest quantum well of the injector sequence. Depending on the bias voltage, dark-current-limited peak detectivities of D*=1×109 cmHz/W (peak wavelength 5 μm at −4 V bias) and of D*=1.3×109 cmHz/W (peak wavelength 3.2 μm at 5 V bias) are obtained at a temperature of 77 K.
SiO
2
-sheathed InS nanowires and SiO2 nanotubes
Authors: Li Y. B. , Bando Y. , Golberg D. , Uemura Y.
Published: November 2003

InS nanowires uniformly sheathed with amorphous SiO2 were synthesized via a physical vapor deposition process. InS nanowires were 20–100 nm in diameter, and the SiO2 sheaths were 5–20 nm in thickness. Single-crystalline InS cores displayed orthorhombic structure and their longitudinal directions were preferentially aligned in the [100] orientation. Pure SiO2 nanotubes of typically round cross sections were also obtained by removing InS cores from the prepared nanocables via thermal evaporation. Photoluminescence measurements on these SiO2 nanotubes demonstrated strong visible-light emission peaked at 570 nm.
Locking of electric-field-induced non-180° domain switching and phase transition in ferroelectric materials upon cyclic electric fatigue
Authors: Liu Ming , Hsia K. Jimmy
Published: November 2003

In situ x-ray diffraction measurements are conducted on a polycrystalline ferroelectric material lead-zironate-titanate-5H at different levels of static electric field. The locking of electric-field-induced non-180° domain switching and phase transition after experiencing cyclic electric field is investigated by examining the changes in pseudocubic diffraction profiles. The results show that cyclic electric field with an amplitude lower than the coercive field has little effect on ferroelectric fatigue of the material, whereas cyclic field with an amplitude above the coercive field results in nearly complete locking of non-180° domain switching and phase transition. The results also demonstrate that the locking occurs rather suddenly after 103–104 cycles. This locking phenomenon can explain the dramatic change in piezoelectric coefficients in these materials upon cyclic electric field.
Temperature dependence of intersubband transitions in InAs/AlSb quantum wells
Authors: Larrabee D. C. , Khodaparast G. A. , Kono J. , Ueda K. , Nakajima Y. , Nakai M. , Sasa S. , Inoue M. , Kolokolov K. I. , Li J. , Ning C. Z.
Published: November 2003

We have carried out a systematic temperature-dependent study of intersubband absorption in InAs/AlSb quantum wells from 5 to 10 nm well width. The resonance energy redshifts with increasing temperature from 10 to 300 K, and the amount of redshift increases with decreasing well width. We have modeled the transitions using eight-band k⋅p theory combined with semiconductor Bloch equations, including the main many-body effects. Temperature is incorporated via band filling and nonparabolicity, and good agreement with experiment is achieved for the temperature dependence of the resonance.
Prominent ferroelectricity of BiFeO3 thin films prepared by pulsed-laser deposition
Authors: Yun Kwi Young , Noda Minoru , Okuyama Masanori
Published: November 2003

Ferroelectric BiFeO3 thin films have been prepared on Pt/TiO2/SiO2/Si substrates in various oxygen pressures of 0.001–0.1 Torr at a temperature as low as 450 °C by pulsed-laser deposition. The crystallinity of the films was studied by x-ray diffraction. X-ray photoelectron spectroscopy showed that the films have a single phase of perovskite BiFeO3. The BiFeO3 thin films deposited at 0.01–0.1 Torr show good current-density–applied-voltage characteristics. It is obtained from polarization–electric-field characterization that 2Pr is about 71.3 μC/cm2 and 2Ec is 125 kV/cm. Stable current density and saturated ferroelectric hysteresis loop have been observed in BiFeO3 thin films.
Thomas Tooke, Henry Thornton, and the Development of British Monetary Orthodoxy
Authors: Skaggs Neil T.
Published: November 2003

The first half of the nineteenth century in Great Britain was one of nearly continuous controversy over monetary issues. The Restriction of Cash Payments and the Bullion Controversy dominated the first two decades. After Resumption in 1821, a series of banking crises kept monetary issues on the front burner, until they boiled over again in the Currency-Banking Controversy of the 1840s. Of the many writers contributing to the monetary literature during the period, few contributed so much as Thomas Tooke. Long recognized as a collector of economic data without peer in his era, Tooke's reputation as an economic theorist has grown in recent years (cf. Laidler 1972; Arnon 1991; M. Smith 2001). Readers of Tooke's works have long known that his views on monetary theory changed radically from the 1820s to the 1840s, when he adopted a starkly anti-quantity theory approach. In his early years as a collector of economic data, Tooke allied himself with David Ricardo in the effort to return Great Britain to the gold standard. But though both subscribed to the quantity-theory/price-specie-flow-mechanism (QT-PSFM) framework for analyzing the economy's adjustment to monetary disturbances, their theoretical approaches differed in important respects. The differences were great enough to lead Arnon (1989, 1991) to conclude that Tooke and Ricardo should be viewed primarily as political, not theoretical, allies and to suggest that Tooke's approach shared greater affinities with the work of moderate bullionists than with Ricardo (Arnon 1991, pp. 48, 58, 108).
Burnout and self-perceived health among Finnish psychiatrists and child psychiatrists: a national survey
Authors: Korkeila Jyrki A. , Töyry Saara , Kumpulainen Kirsti , Toivola Juha-Matti , Räsänen Kimmo , Kalimo Raija
Published: November 2003

Aims: This study investigated burnout and related health matters among a sample of Finnish physicians working within the field of psychiatry. Methods: A postal questionnaire was sent to one in three licensed physicians randomly selected from the register of the Finnish Medical Association (FMA). The response rate was 74% ( n=3133). Results: Psychiatrists and child psychiatrists reported burnout, threat of severe burnout, depression, and mental disorder more commonly than other physicians. Moreover, psychiatrists and child psychiatrists reported less often ``good'' or ``rather good'' self-perceived health. Depression had a moderate positive correlation with overall MBI score. Lack of possibilities to consult a colleague, and supervision of work, experience of threat of violence, and self-reported depression were significantly associated with overall burnout level and emotional exhaustion. Conclusions: Emotional exhaustion as a symptom of burnout was common among psychiatrists, especially among those working in community care, and child psychiatrists. Problems of general health, as well as mental health, among psychiatrists and child psychiatrists are in need of attention.
Adulthood mortality of infants isolated at birth due to tuberculosis in the family
Authors: Veijola Juha M. , Mäki Pirjo H. , Joukamaa Matti I. , Läärä Esa , Hakko Helinä , Nieminen Markku M. , Isohanni Matti K.
Published: November 2003

Aims: In 1936 the Finnish Anti-Tuberculosis Association founded the first nursery, `` Joulumerkkikoti '', into which infants born into tuberculous families were admitted and given BCG vaccination to reduce the risk of tuberculosis. This prophylactic regimen was effective in reducing infant mortality and morbidity of tuberculosis. We investigated the mortality of these children later in childhood and adulthood. Methods: The index cohort consisted of 3,020 subjects born between 1945 and 1965 in Finland and isolated from their family immediately after birth. The average separation time was 218 days. The subjects alive on 1 January 1971 were identified. For every index subject two reference subjects were chosen, the matching criteria being sex, year, and place of birth. Data on causes of deaths were obtained from the Finnish Cause of Death Registry by the end of 1998. Results: The relative mortality rate (RR) was higher in the index cohort than in the reference cohort for all causes of death (RR 1.4; 95% CI 1.2—1.7), and particularly for unnatural deaths: RR 1.5 (1.1—1.9) for men and RR 1.9 (1.0—3.7) for women. Conclusions : The mortality in the index subjects later in childhood and adulthood was somewhat elevated. This may be explained by a variety of risks experienced during pregnancy, delivery, and childhood. The fall in the socioeconomic status of the family of origin due to tuberculosis may partially explain the result. Another interpretation is that the very early separation from the mother had unfavourable effects on later psychological developments in some children.
Long-term effects of widowhood after terminal cancer: a Swedish nationwide follow-up
Authors: Valdimarsdóttir Unnur , Helgason Ásgeir R. , Fürst Carl-Johan , Adolfsson Jan , Steineck Gunnar
Published: November 2003

Aims: The authors investigated whether becoming a widow after the death of a husband from cancer results in long-term psychological or physical morbidity.

Method: In April and May 1999, an attempt was made to contact all of the 506 women who were living with men dying of prostate cancer in 1996 or of urinary bladder cancer in 1995 or 1996, as well as 287 population controls.

Results: Completed questionnaires were received from 379 of the widows and 220 of the controls. Widowhood was associated with a low or moderate subjective quality of life (relative risk [RR]=1.4, 95% confidence interval 1.2—1.7), low or moderate psychological well-being (RR=1.8, 1.4—2.3), anxiety (RR=1.9, 1.3—2.7), depression (RR=2.2, 1.6—2.9), sleep disturbances (RR=1.9, 1.5—2.4), diabetes (RR=3.5, 1.2—7.9), and economic dissatisfaction (RR=1.6, 1.3—2.0).

Conclusion: An excess risk of psychological morbidity, diabetes mellitus and dissatisfaction with the economic situation was found in the widowed population.
Requirement of Phosphatidylglycerol for Maintenance of Photosynthetic Machinery
Authors: Sakurai Isamu , Hagio Miki , Gombos Zoltan , Tyystjärvi Taina , Paakkarinen Virpi , Aro Eva-Mari , Wada Hajime
Published: November 2003

Phosphatidylglycerol (PG) is a ubiquitous component of thylakoid membranes. Experiments with the pgsA mutant of the cyanobacterium Synechocystis sp. PCC6803 defective in biosynthesis of PG have demonstrated an indispensable role of PG in photosynthesis. In the present study, we have investigated the light susceptibility of the pgsA mutant with regard to the maintenance of the photosynthetic machinery. Growth of the mutant cells without PG increased the light susceptibility of the cells and resulted in severe photoinhibition of photosynthesis upon a high-light treatment, whereas the growth in the presence of PG was protected against photoinhibition. Photoinhibition induced by PG deprivation was mainly caused by an impairment of the restoration process. The primary target of the light-induced damage in thylakoid membranes, the D1 protein of photosystem (PS) II was, however, synthesized and degraded with similar rates irrespective of whether the mutant cells were incubated with PG or not. Intriguingly, it was found that instead of the synthesis of the D1 protein, the dimerization of the PSII core monomers was impaired in the PG-deprived mutant cells. Addition of PG to photoinhibited cells restored the dimerization capacity of PSII core monomers. These results suggest that PG plays an important role in the maintenance of the photosynthetic machinery through the dimerization and reactivation of the PSII core complex.
International Technology Diffusion: Evidence from Swedish Patent Data
Authors: Globerman Steve , Kokko Ari , Sjöholm Fredrik
Published: November 2003

Using references in Swedish patent data, we examine technology sourcing in Swedish multi‐national enterprises (MNEs) and non‐multinational small and medium‐sized enterprises (SMEs). The results show that both types of firms are more likely to make references to countries with large patent stocks and to countries that are located close to Sweden. Trade and FDI also seem to facilitate the transfer of foreign technology to Sweden. However, trade contacts seem to be more important for technology sourcing in SMEs than in MNEs. Outward Foreign Direct Investment (FDI) is a channel for the diffusion of foreign technology to both home‐country MNEs and SMEs.
Producers' Expectations: their Role in the Monetary Transmission Mechanism
Authors: Rötheli Tobias F.
Published: November 2003

This article relates to the view expressed by Pigou and Keynes that whatever factors affect the demand for goods it is ultimately producers' expectations and plans that determine the level of output. We build on this notion in order to address the question how changes in monetary policy affect output in Switzerland. For this purpose we study data on expected and actual output collected by the business cycle research center(KOF) at the Federal Institute of Technology (ETH) in Zürich. The econometric analysis documents that monetary affect output only by their impact on expectations of entrepreneurs. This finding contradicts the new classical view of the propagation of monetary shocks.
Income Inequality and Economic Growth
Authors: Mo Pak Hung
Published: November 2003

We develop an analytical framework to investigate some plausible channels that income inequality affects economic growth. Our empirical study concludes that income inequality has significant negative effect on the rate of GDP growth. Among the channels suggested by recent literature, we find that the most important one is the transfer channel while the least important one is the human capital channel. However, the direct impact of income inequality on the rate of productivity growth accounts for more than 55 percent of its overall total effect. This indicates that the effects of income inequality on economic growth are much more complicated than what we have perceived or modeled.