WorldWideScience

Sample records for amorphous ge bipolar

  1. Bipolar resistive switching behavior of an amorphous Ge2Sb2Te5 thin films with a Te layer

    Science.gov (United States)

    Yoo, Sijung; Eom, Taeyong; Gwon, Taehong; Hwang, Cheol Seong

    2015-03-01

    The mechanism of bipolar resistive switching (BRS) of amorphous Ge2Sb2Te5 (GST) thin films sandwiched between inert electrodes (Ti and Pt) was examined. Typical bipolar resistive switching behavior with a high resistance ratio (~103) and reliable switching characteristics was achieved. High-resolution transmission electron microscopy revealed the presence of a conductive Te-filament bridging between the top and bottom electrodes through an amorphous GST matrix. The conduction mechanism analysis showed that the low-resistance state was semiconducting and dominated by band transport, whereas Poole-Frenkel conduction governed the carrier transport in the high-resistance state. Thus, the BRS behavior can be attributed to the formation and rupture of the semiconducting conductive Te bridge through the migration of the Te ions in the amorphous GST matrix under a high electric field. The Te ions are provided by the thin (~5 nm) Te-rich layer formed at the bottom electrode interface.

  2. Femtosecond laser crystallization of amorphous Ge

    Science.gov (United States)

    Salihoglu, Omer; Kürüm, Ulaş; Yaglioglu, H. Gul; Elmali, Ayhan; Aydinli, Atilla

    2011-06-01

    Ultrafast crystallization of amorphous germanium (a-Ge) in ambient has been studied. Plasma enhanced chemical vapor deposition grown a-Ge was irradiated with single femtosecond laser pulses of various durations with a range of fluences from below melting to above ablation threshold. Extensive use of Raman scattering has been employed to determine post solidification features aided by scanning electron microscopy and atomic force microscopy measurements. Linewidth of the Ge optic phonon at 300 cm-1 as a function of laser fluence provides a signature for the crystallization of a-Ge. Various crystallization regimes including nanostructures in the form of nanospheres have been identified.

  3. Parametrized dielectric functions of amorphous GeSn alloys

    Science.gov (United States)

    D'Costa, Vijay Richard; Wang, Wei; Schmidt, Daniel; Yeo, Yee-Chia

    2015-09-01

    We obtained the complex dielectric function of amorphous Ge1-xSnx (0 ≤ x ≤ 0.07) alloys using spectroscopic ellipsometry from 0.4 to 4.5 eV. Amorphous GeSn films were formed by room-temperature implantation of phosphorus into crystalline GeSn alloys grown by molecular beam epitaxy. The optical response of amorphous GeSn alloys is similar to amorphous Ge and can be parametrized using a Kramers-Kronig consistent Cody-Lorentz dispersion model. The parametric model was extended to account for the dielectric functions of amorphous Ge0.75Sn0.25 and Ge0.50Sn0.50 alloys from literature. The compositional dependence of band gap energy Eg and parameters associated with the Lorentzian oscillator have been determined. The behavior of these parameters with varying x can be understood in terms of the alloying effect of Sn on Ge.

  4. Early effect of SiGe heterojunction bipolar transistors

    Science.gov (United States)

    Xu, Xiao-Bo; Zhang, He-Ming; Hu, Hui-Yong; Qu, Jiang-Tao

    2012-06-01

    The standard Early voltage of the SGP model is generalized for SiGe NPN heterojunction bipolar transistors (HBTs). A new compact formulation of the Early voltage compatible with the SGP model is presented. The impact of the Ge profile on Early effect is shown and validated by experiments. The model can be applied to the SGP model for circuit simulation.

  5. Atomistic simulation of damage accumulation and amorphization in Ge

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Selles, Jose L., E-mail: joseluis.gomezselles@imdea.org; Martin-Bragado, Ignacio [IMDEA Materials Institute, Eric Kandel 2, 28906 Getafe, Madrid (Spain); Claverie, Alain [CEMES/CNRS, 29 rue J. Marvig, 31055 Toulouse Cedex (France); Sklenard, Benoit [CEA, LETI, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Benistant, Francis [GLOBALFOUNDRIES Singapore Pte Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore)

    2015-02-07

    Damage accumulation and amorphization mechanisms by means of ion implantation in Ge are studied using Kinetic Monte Carlo and Binary Collision Approximation techniques. Such mechanisms are investigated through different stages of damage accumulation taking place in the implantation process: from point defect generation and cluster formation up to full amorphization of Ge layers. We propose a damage concentration amorphization threshold for Ge of ∼1.3 × 10{sup 22} cm{sup −3} which is independent on the implantation conditions. Recombination energy barriers depending on amorphous pocket sizes are provided. This leads to an explanation of the reported distinct behavior of the damage generated by different ions. We have also observed that the dissolution of clusters plays an important role for relatively high temperatures and fluences. The model is able to explain and predict different damage generation regimes, amount of generated damage, and extension of amorphous layers in Ge for different ions and implantation conditions.

  6. Bipolar resistive switching behavior of an amorphous Ge₂Sb₂Te₅ thin films with a Te layer.

    Science.gov (United States)

    Yoo, Sijung; Eom, Taeyong; Gwon, Taehong; Hwang, Cheol Seong

    2015-04-14

    The mechanism of bipolar resistive switching (BRS) of amorphous Ge2Sb2Te5 (GST) thin films sandwiched between inert electrodes (Ti and Pt) was examined. Typical bipolar resistive switching behavior with a high resistance ratio (∼10(3)) and reliable switching characteristics was achieved. High-resolution transmission electron microscopy revealed the presence of a conductive Te-filament bridging between the top and bottom electrodes through an amorphous GST matrix. The conduction mechanism analysis showed that the low-resistance state was semiconducting and dominated by band transport, whereas Poole-Frenkel conduction governed the carrier transport in the high-resistance state. Thus, the BRS behavior can be attributed to the formation and rupture of the semiconducting conductive Te bridge through the migration of the Te ions in the amorphous GST matrix under a high electric field. The Te ions are provided by the thin (∼5 nm) Te-rich layer formed at the bottom electrode interface.

  7. Parametrized dielectric functions of amorphous GeSn alloys

    Energy Technology Data Exchange (ETDEWEB)

    D' Costa, Vijay Richard, E-mail: elevrd@nus.edu.sg; Wang, Wei; Yeo, Yee-Chia, E-mail: eleyeoyc@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Schmidt, Daniel [Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603 (Singapore)

    2015-09-28

    We obtained the complex dielectric function of amorphous Ge{sub 1−x}Sn{sub x} (0 ≤ x ≤ 0.07) alloys using spectroscopic ellipsometry from 0.4 to 4.5 eV. Amorphous GeSn films were formed by room-temperature implantation of phosphorus into crystalline GeSn alloys grown by molecular beam epitaxy. The optical response of amorphous GeSn alloys is similar to amorphous Ge and can be parametrized using a Kramers-Kronig consistent Cody-Lorentz dispersion model. The parametric model was extended to account for the dielectric functions of amorphous Ge{sub 0.75}Sn{sub 0.25} and Ge{sub 0.50}Sn{sub 0.50} alloys from literature. The compositional dependence of band gap energy E{sub g} and parameters associated with the Lorentzian oscillator have been determined. The behavior of these parameters with varying x can be understood in terms of the alloying effect of Sn on Ge.

  8. Epitaxial growth of amorphous Ge films deposited on single-crystal Ge

    OpenAIRE

    M. G. Grimaldi; Mäenpää, M. (Markus); Paine, B. M.; Nicolet, M-A.; Lau, S. S.; Tseng, W. F.

    1981-01-01

    The epitaxial growth of amorphous Ge films deposited onto 110 Ge substrate is demonstrated. Substrate cleaning prior to deposition involves only conventional chemical procedures. The growth appears to be a strong function of the interface cleanliness. Two different growth mechanisms are observed: (a) a direct transition from amorphous to single-crystalline layer and (b) the growth involving the transition of amorphous to polycrystals to single crystal.

  9. Development of Microwave SiGe Heterojunction Bipolar Transistors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The microwave SiGe Heterojunction Bipolar Transistors (HBT) were fabricated by the material grown with home-made high vacuum/rapid thermal processing chemical vapor deposition equipment. The HBTs show good performance and industrial use value. The current gain is beyond 100;the breakdown voltage BVceo is 3.3V,and the cut-off frequency is 12.5GHz which is measured in packaged form.

  10. Structural origin of resistance drift in amorphous GeTe

    Science.gov (United States)

    Zipoli, Federico; Krebs, Daniel; Curioni, Alessandro

    2016-03-01

    We used atomistic simulations to study the origin of the change of resistance over time in the amorphous phase of GeTe, a prototypical phase-change material (PCM). Understanding the cause of resistance drift is one of the biggest challenges to improve multilevel storage technology. For this purpose, we generated amorphous structures via classical molecular-dynamics simulations under conditions as close as possible to the experimental operating ones of such memory devices. Moreover, we used the replica-exchange technique to generate structures comparable with those obtained in the experiment after long annealing that show an increase of resistance. This framework allowed us to overcome the main limitation of previous simulations, based on density-functional theory, that suffered from being computationally too expensive therefore limited to the nanosecond time scale. We found that resistance drift is caused by consumption of Ge atom clusters in which the coordination of at least one Ge atom differs from that of the crystalline phase and by removal of stretched bonds in the amorphous network, leading to a shift of the Fermi level towards the middle of the band gap. These results show that one route to design better memory devices based on current chalcogenide alloys is to reduce the resistance drift by increasing the rigidity of the amorphous network.

  11. 1/F Noise in Amorphous GeTe.

    Science.gov (United States)

    1976-06-18

    AD—A035 105 NAVAL SURFACE WEAPONS CEN TeR WHITE OAK LAB SILVER SP——ETC F/S 20/12 1/F NOISE IN AMORPHOUS IElt .(U) ani 76 K P SCHARNI4O*ST UNCLASSIFIED... preparation procedure had to be used. Six millimeter long sections of amorphous GeTe of different thicknesses and widths were deposited on 10 to 20 mil...structure and have initiated an effort to improve our sample preparation procedure. Exposure of samples to ambient during transfer from one evaporator

  12. Ion implantation damage and crystalline-amorphous transition in Ge

    Energy Technology Data Exchange (ETDEWEB)

    Impellizzeri, G.; Mirabella, S.; Grimaldi, M.G. [Universita di Catania, MATIS IMM-CNR (Italy); Dipartimento di Fisica e Astronomia, Catania (Italy)

    2011-05-15

    Experimental studies on the damage produced in (100) Ge substrates by implantation of Ge{sup +} ions at different energies (from 25 to 600 keV), fluences (from 2 x 10{sup 13} to 4 x 10{sup 14} cm{sup -2}) and temperature (room temperature, RT, or liquid-nitrogen temperature, LN{sub 2}T) have been performed by using the Rutherford backscattering spectrometry technique. We demonstrated that the higher damage rate of Ge with respect to Si is due to both the high stopping power of germanium atoms and the low mobility of point defects within the collision cascades. The amorphization of Ge has been modeled by employing the critical damage energy density model in a large range of implantation energies and fluences both at RT and LN{sub 2}T. The experimental results for implantation at LN{sub 2}T were fitted using a critical damage energy density of {proportional_to}1 eV/atom. A fictitious value of {proportional_to}5 eV/atom was obtained for the samples implanted at RT, essentially because at RT the damage annihilation plays a non-negligible role against the crystalline-amorphous transition phase. The critical damage energy density model was found to stand also for other ions implanted in crystalline Ge (Ar{sup +} and Ga{sup +}). (orig.)

  13. Amorphous inclusions during Ge and GeSn epitaxial growth via chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gencarelli, F., E-mail: federica.gencarelli@imec.be [imec, Kapeldreef 75, 3001 Leuven (Belgium); Dept. of Metallurgy and Materials Engineering, KU Leuven, B-3001 Leuven (Belgium); Shimura, Y. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Kumar, A. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Vincent, B.; Moussa, A.; Vanhaeren, D.; Richard, O.; Bender, H. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Vandervorst, W. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Caymax, M.; Loo, R. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Heyns, M. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Dept. of Metallurgy and Materials Engineering, KU Leuven, B-3001 Leuven (Belgium)

    2015-09-01

    In this work, we discuss the characteristics of particular island-type features with an amorphous core that are developed during the low temperature epitaxial growth of Ge and GeSn layers by means of chemical vapor deposition with Ge{sub 2}H{sub 6}. Although further investigations are needed to unambiguously identify the origin of these features, we suggest that they are originated by the formation of clusters of H and/or contaminants atoms during growth. These would initially cause the formation of pits with crystalline rough facets over them, resulting in ring-shaped islands. Then, when an excess surface energy is overcome, an amorphous phase would nucleate inside the pits and fill them. Reducing the pressure and/or increasing the growth temperature can be effective ways to prevent the formation of these features, likely due to a reduction of the surface passivation from H and/or contaminant atoms. - Highlights: • Island features with amorphous cores develop during low T Ge(Sn) CVD with Ge{sub 2}H{sub 6.} • These features are thoroughly characterized in order to understand their origin. • A model is proposed to describe the possible evolution of these features. • Lower pressures and/or higher temperatures avoid the formation of these features.

  14. Mechanical properties of bismuth implanted amorphous Ge film

    Energy Technology Data Exchange (ETDEWEB)

    Juhasz, A.; Szommer, P.; Lendvai, J.; Vertesy, Z.; Peto, G. E-mail: peto@mfa.kfki.hu

    1999-01-02

    Mechanical properties of Bi ion implanted a-Ge film were studied by dynamic microhardness tests and compared to those of unimplanted a-Ge film. 400 nm thick films were evaporated in units of 30 nm thick layers and bombarded with Bi ions at 60 keV energy and 2 {mu}A/cm{sup 2} current. Cyclic load-unload indentation tests and indentation creep tests were performed to determine the hardness and ductility of the ion implanted and unimplanted specimens, respectively. The brittleness of the materials was characterised by scanning electron microscopic observation of crack formation around the Vickers indentations. The dynamic hardness was much larger, the ductility lower, the crack formation was significantly larger in the case of the unimplanted than in the ion bombarded specimens. The observed differences in the mechanical properties indicate structural differences between the two types of a-Ge are in agreement with the earlier reported formation of a new amorphous phase of Ge induced by ion implantation (G. Peto, J. Kanski, U. Sodervall, Phys. Lett. 124 (1987) 510)

  15. Mechanical properties of bismuth implanted amorphous Ge film

    Science.gov (United States)

    Juhász, A.; Szommer, P.; Lendvai, J.; Vértesy, Z.; Pető, G.

    1999-01-01

    Mechanical properties of Bi ion implanted a-Ge film were studied by dynamic microhardness tests and compared to those of unimplanted a-Ge film. 400 nm thick films were evaporated in units of 30 nm thick layers and bombarded with Bi ions at 60 keV energy and 2 μA/cm 2 current. Cyclic load-unload indentation tests and indentation creep tests were performed to determine the hardness and ductility of the ion implanted and unimplanted specimens, respectively. The brittleness of the materials was characterised by scanning electron microscopic observation of crack formation around the Vickers indentations. The dynamic hardness was much larger, the ductility lower, the crack formation was significantly larger in the case of the unimplanted than in the ion bombarded specimens. The observed differences in the mechanical properties indicate structural differences between the two types of a-Ge are in agreement with the earlier reported formation of a new amorphous phase of Ge induced by ion implantation (G. Pető, J. Kanski, U. Sodervall, Phys. Lett. 124 (1987) 510 [6]).

  16. Structural Changes of Amorphous GeTe2 Films by Annealing (Formation of Metastable Crystalline GeTe2 Films)

    Science.gov (United States)

    Fukumoto, Hirofumi; Tsunetomo, Keiji; Imura, Takeshi; Osaka, Yukio

    1987-01-01

    Amorphous GeTe2 films with the thickness ˜0.5 μm, prepared by sputtering technique, transform into the crystalline GeTe2 films with the isomorphic structure to β-cristobalite, cubic SiO2, at Ta(annealing temperature){=}200°C. The cubic phase of GeTe2 is metastable and decomposes into the mixed crystal of GeTe and Te at Ta{=}250°C.

  17. Molecular dynamics simulation of ion-beam-amorphization of Si, Ge and GaAs

    CERN Document Server

    Nord, J D; Keinonen, J

    2002-01-01

    We use molecular dynamics simulations to study ion-irradiation-induced amorphization in Si, Ge and GaAs using several different interatomic force models. We find that the coordination number is higher, and the average bond length longer, for the irradiated amorphous structures than for the molten ones in Si and Ge. For amorphous GaAs, we suggest that longer Ga-Ga bonds, also present in pure Ga, are produced during the irradiation. In Si the amorphization is found to proceed via growth of amorphous regions, and low energy recoils are found to induce athermal recrystallization during irradiation.

  18. The Role of the Silicon Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) in Mobile Technology Platforms

    Science.gov (United States)

    2011-09-01

    The Role of the Silicon Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) in Mobile Technology Platforms by Gregory A. Mitchell...Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) in Mobile Technology Platforms 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...MD 20783-1197 ARL-TN-0459 September 2011 The Role of the Silicon Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) in Mobile

  19. Intrinsic complexity of the melt-quenched amorphous Ge2Sb2Te5 memory alloy

    Science.gov (United States)

    Krbal, M.; Kolobov, A. V.; Fons, P.; Tominaga, J.; Elliott, S. R.; Hegedus, J.; Uruga, T.

    2011-02-01

    Through the use of first-principles Ge K-edge XANES simulations we demonstrate that the structure of melt-quenched amorphous Ge-Sb-Te is intrinsically complex and is a mixture of Ge(3):Te(3) and Ge(4):Te(2) configurations in comparable concentrations, in contrast to the as-deposited amorphous phase that is dominated by the Ge(4):Te(2) configurations. The reasons for Ge-Te polyvalency are discussed and it is argued that both configurations are compatible with the Mott 8-N rule and the definition of an ideal amorphous solid. The near-perfect Te-Te distance match between the two major configurations accounts for the high cyclability of phase-change materials. Stable compositions in the Ge-Sb-Te system are suggested.

  20. Black GE based on crystalline/amorphous core/shell nanoneedle arrays

    Science.gov (United States)

    Javey, Ali; Chueh, Yu-Lun; Fan, Zhiyong

    2014-03-04

    Direct growth of black Ge on low-temperature substrates, including plastics and rubber is reported. The material is based on highly dense, crystalline/amorphous core/shell Ge nanoneedle arrays with ultrasharp tips (.about.4 nm) enabled by the Ni catalyzed vapor-solid-solid growth process. Ge nanoneedle arrays exhibit remarkable optical properties. Specifically, minimal optical reflectance (black Ge can have important practical implications for efficient photovoltaic and photodetector applications on nonconventional substrates.

  1. Charge storage characteristics and tunneling mechanism of amorphous Ge-doped HfOx films

    Science.gov (United States)

    Qiu, X. Y.; Zhang, S. Y.; Zhang, T.; Wang, R. X.; Li, L. T.; Zhang, Y.; Dai, J. Y.

    2016-09-01

    Amorphous Ge-doped HfOx films have been deposited on p-Si(100) substrates by means of RF magnetron sputtering. Microstructural investigations reveal the partial oxidation of doped Ge atoms in the amorphous HfOx matrix and the existence of HfSiOx interfacial layer. Capacitance-voltage hysteresis of the Ag-/Ge-doped HfOx/Si/Ag memory capacitor exhibits a memory window of 3.15 V which can maintain for >5 × 104 cycles. Current-voltage characteristics reveal that Poole-Frenkel tunneling is responsible for electron transport in the Ge-doped HfOx film.

  2. Anisotropic phase separation through the metal-insulator transition in amorphous Mo-Ge and Fe-Ge alloys

    Energy Technology Data Exchange (ETDEWEB)

    Regan, M.J.

    1993-12-01

    Since an amorphous solid is often defined as that which lacks long-range order, the atomic structure is typically characterized in terms of the high-degree of short-range order. Most descriptions of vapor-deposited amorphous alloys focus on characterizing this order, while assuming that the material is chemically homogeneous beyond a few near neighbors. By coupling traditional small-angle x-ray scattering which probes spatial variations of the electron density with anomalous dispersion which creates a species-specific contrast, one can discern cracks and voids from chemical inhomogeneity. In particular, one finds that the chemical inhomogeneities which have been previously reported in amorphous Fe{sub x}Ge{sub 1-x} and Mo{sub x}Ge{sub 1-x} are quite anisotropic, depending significantly on the direction of film growth. With the addition of small amounts of metal atoms (x<0.2), no films appear isotropic nor homogeneous through the metal/insulator transition. The results indicate that fluctuations in the growth direction play a pivotal role in preventing simple growth models of a columnar structure or one that evolves systematically as it grows. The anomalous scattering measurements identify the metal atoms (Fe or Mo) as the source of the anisotropy, with the Ge atoms distributed homogeneously. The author has developed a method for using these measurements to determine the compositions of the phase-separating species. The results indicate phase separation into an amorphous Ge and an intermetallic phase of stoichiometry close to FeGe{sub 2} or MoGe{sub 3}. Finally, by manipulating the deposited power flux and rates of growth, Fe{sub x}Ge{sub 1-x} films which have the same Fe composition x can be grown to different states of phase separation. These results may help explain the difficulty workers have had in isolating the metal/insulator transition for these and other vapor-deposited amorphous alloys.

  3. Nanostructuring of GeTiO amorphous films by pulsed laser irradiation

    Directory of Open Access Journals (Sweden)

    Valentin S. Teodorescu

    2015-04-01

    Full Text Available Laser pulse processing of surfaces and thin films is a useful tool for amorphous thin films crystallization, surface nanostructuring, phase transformation and modification of physical properties of thin films. Here we show the effects of nanostructuring produced at the surface and under the surface of amorphous GeTiO films through laser pulses using fluences of 10–30 mJ/cm2. The GeTiO films were obtained by RF magnetron sputtering with 50:50 initial atomic ratio of Ge:TiO2. Laser irradiation was performed by using the fourth harmonic (266 nm of a Nd:YAG laser. The laser-induced nanostructuring results in two effects, the first one is the appearance of a wave-like topography at the film surface, with a periodicity of 200 nm and the second one is the structure modification of a layer under the film surface, at a depth that is related to the absorption length of the laser radiation. The periodicity of the wave-like relief is smaller than the laser wavelength. In the modified layer, the Ge atoms are segregated in spherical amorphous nanoparticles as a result of the fast diffusion of Ge atoms in the amorphous GeTiO matrix. The temperature estimation of the film surface during the laser pulses shows a maximum of about 500 °C, which is much lower than the melting temperature of the GeTiO matrix. GeO gas is formed at laser fluences higher than 20 mJ/cm2 and produces nanovoids in the laser-modified layer at the film surface. A glass transition at low temperatures could happen in the amorphous GeTiO film, which explains the formation of the wave-like topography. The very high Ge diffusivity during the laser pulse action, which is characteristic for liquids, cannot be reached in a viscous matrix. Our experiments show that the diffusivity of atomic and molecular species such as Ge and GeO is very much enhanced in the presence of the laser pulse field. Consequently, the fast diffusion drives the formation of amorphous Ge nanoparticles through the

  4. Tuning the properties of Ge-quantum dots superlattices in amorphous silica matrix through deposition conditions

    OpenAIRE

    Pinto, S. R. C.; Buljan, M.; Chahboun, A.; M. A. Roldan; Bernstorff, S.; Varela, M.; S. J. Pennycook; Barradas, N. P.; Alves, E.; Molina, S.I.; Ramos, Marta M. D.; Gomes, M.J.M.

    2012-01-01

    In this work, we investigate the structural properties of Ge quantum dot lattices in amorphous silica matrix, prepared by low-temperature magnetron sputtering deposition of (GeþSiO2)/SiO2 multilayers. The dependence of quantum dot shape, size, separation, and arrangement type on the Ge-rich (GeþSiO2) layer thickness is studied. We show that the quantum dots are elongated along the growth direction, perpendicular to the multilayer surface. The size of the quantum dots and their separation a...

  5. Computer generation of structural models of amorphous Si and Ge

    Science.gov (United States)

    Wooten, F.; Winer, K.; Weaire, D.

    1985-04-01

    We have developed and applied a computer algorithm that generates realistic random-network models of a-Si with periodic boundary conditions. These are the first models to have correlation functions that show no serious deiscrepancy with experiment. The algorithm provides a much-needed systematic approach to model construction that can be used to generate models of a large class of amorphous materials.

  6. Structural studies of the phase separation of amorphous FexGe100-x alloys

    Science.gov (United States)

    Lorentz, Robert D.; Bienenstock, Arthur; Morrison, Timothy I.

    1994-02-01

    Small-angle x-ray scattering and x-ray-absorption near-edge spectroscopy (XANES) experiments have been performed on amorphous FexGe100-x alloys over the composition range 0Janot for the related FexSn100-x system. This phase separation explains the Mossbauer observation of ``magnetic'' and ``nonmagnetic'' Fe atoms in these alloys.

  7. Stoichiometry dependence of resistance drift phenomena in amorphous GeSnTe phase-change alloys

    Science.gov (United States)

    Luckas, J.; Piarristeguy, A.; Bruns, G.; Jost, P.; Grothe, S.; Schmidt, R. M.; Longeaud, C.; Wuttig, M.

    2013-01-01

    In phase-change materials, the amorphous state resistivity increases with time following a power law ρ ∝ (t/t0)αRD. This drift in resistivity seriously hampers the potential of multilevel-storage to achieve an increased capacity in phase-change memories. This paper presents the stoichiometric dependence of drift phenomena in amorphous GeSnTe systems (a-GeSnTe) and other known phase-change alloys with the objective to identify low drift materials. The substitution of Ge by Sn results in a systematic decrease of the drift parameter from a-GeTe (αRD = 0.129) to a-Ge2Sn2Te4 (αRD = 0.053). Furthermore, with increasing Sn content a decrease in crystallization temperature, trap state density, optical band gap, and activation energy for electronic conduction is observed. In a-GeSnTe, a-GeSbTe, and a-AgInSbTe alloys as well, the drift parameter αRD correlates to the activation energy for electronic conduction. This study indicates that low drift materials are characterized by low activation energies of electronic conduction. The correlation found between drift and activation energy of electronic conduction manifests a useful criterion for material optimization.

  8. Nanoporosity induced by ion implantation in deposited amorphous Ge thin films

    Energy Technology Data Exchange (ETDEWEB)

    Romano, L.; Impellizzeri, G.; Ruffino, F.; Miritello, M.; Grimaldi, M. G. [IMM-CNR MATIS and Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Bosco, L. [Scuola Superiore di Catania, Via Valdisavoia 9, I-95123 Catania (Italy)

    2012-06-01

    The formation of a nano-porous structure in amorphous Ge thin film (sputter-deposited on SiO{sub 2}) during ion irradiation at room temperature with 300 keV Ge{sup +} has been observed. The porous film showed a sponge-like structure substantially different from the columnar structure reported for ion implanted bulk Ge. The voids size and structure resulted to be strongly affected by the material preparation, while the volume expansion turned out to be determined only by the nuclear deposition energy. In SiGe alloys, the swelling occurs only if the Ge concentration is above 90%. These findings rely on peculiar characteristics related to the mechanism of voids nucleation and growth, but they are crucial for future applications of active nanostructured layers such as low cost chemical and biochemical sensing devices or electrodes in batteries.

  9. Nanocrystals and amorphous matrix phase studies of Finemet-like alloys containing Ge

    Energy Technology Data Exchange (ETDEWEB)

    Moya, J.A., E-mail: jmoya.fi.uba@gmail.co [IESIING, Facultad de Ingenieria e Informatica, UCASAL, A4402FYP Salta (Argentina); Lab. Solidos Amorfos, Facultad de Ingenieria, INTECIN, UBA-CONICET (Argentina); CONICET (Argentina)

    2010-07-15

    Two simple models were developed in order to determine the chemical composition of both nanocrystals and intergranular amorphous phases in nanocrystallized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} containing Ge using data from X-ray diffraction and Moessbauer spectroscopy techniques. Saturation magnetization of the amorphous intergranular matrix (M{sub s}{sup am}) was calculated considering the contribution of the alpha-Fe(Si,Ge) nanocrystals and saturation magnetization of the alloys. The behavior of M{sub s}{sup am} with the iron content of the matrix was obtained and discussed. The exchange stiffness constant for the nanograins and for the amorphous phases was determined. The increment in the coercive field (H{sub c}) with increasing Ge content was evaluated using two theoretical models for the random magnetocrystalline anisotropy constant (). Results show that the magnetic hardening observed could not be attributed to an increase in but mainly to an important increment of the magnetostriction constant of the alpha-Fe(Si,Ge) nanocrystals (lambda{sub s}{sup cr}). Values for lambda{sub s}{sup cr} are proposed.

  10. Radiative lifetime of geminate and non-geminate pairs in amorphous semiconductors: a-Ge:H

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jai [Faculty of Technology, Charles Darwin University, Darwin, NT 0909 (Australia)

    2006-07-01

    Lifetimes of radiative recombination of geminate and non-geminate pairs in amorphous semiconductors are calculated at thermal equilibrium. The theory is applied to calculate the radiative lifetimes of type I and II geminate pairs and non-geminate pairs in hydrogenated amorphous germanium (a-Ge:H) and compared with the experimental results. The type II geminate pairs can exist in singlet and triplet spin states, only singlet is considered here, whereas the type I geminate pairs do not have spin dependence. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Synthesis and size differentiation of Ge nanocrystals in amorphous SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Agan, S. [University of Illinois, Department of Materials Science and Engineering, Urbana, IL (United States); Kirikale University, Physics Department, Kirikale (Turkey); Celik-Aktas, A. [University of Illinois, Department of Nuclear, Plasma and Radiological Engineering, Urbana, IL (United States); Zuo, J.M. [University of Illinois, Department of Materials Science and Engineering, Urbana, IL (United States); Dana, A.; Aydinli, A. [Bilkent University, Physics Department, Ankara (Turkey)

    2006-04-15

    Germanosilicate layers were grown on Si substrates by plasma enhanced chemical vapor deposition (PECVD) and annealed at different temperatures ranging from 700-1010 C for durations of 5 to 60 min. Transmission electron microscopy (TEM) was used to investigate Ge nanocrystal formation in SiO{sub 2}:Ge films. High-resolution cross section TEM images, electron energy-loss spectroscopy and energy dispersive X-ray analysis (EDX) data indicate that Ge nanocrystals are present in the amorphous silicon dioxide films. These nanocrystals are formed in two spatially separated layers with average sizes of 15 and 50 nm, respectively. EDX analysis indicates that Ge also diffuses into the Si substrate. (orig.)

  12. Study of Cutoff Frequency of High Collector Current Density in SiGe Single-Heterojunction Bipolar Transistor

    Directory of Open Access Journals (Sweden)

    G. M. Khanduri

    2004-01-01

    Full Text Available The cutoff frequency performance of an NPN Si/SiGe/SiGe Single-heterojunction bipolar transistor (SiGe SHBT at high collector current densities has been analyzed using a 2-dimensional MEDICI device simulator. A conventional NPN Si/SiGe/Si Double-heterojunction bipolar transistor (SiGe DHBT having uniform 14%Ge in the base region has been investigated for comparison. The analysis shows the formation of a retarding potential barrier for minority carrier electrons at the basecollector heterojunction of the DHBT structure. Whereas, the base-collector homojunction of the SiGe SHBT structure, having a uniform 14%Ge profile in its base and collector, inhibits the formation of such a retarding potential barrier. The SHBT structure with a base-collector homojunction shows an Improved cutoff frequency at a high collector current density in comparison with conventional SiGe DHBT, which makes it more promising for high speed, scaled down, field-specific applications.

  13. Modal Contributions to Heat Conduction across Crystalline and Amorphous Si/Ge Interfaces

    Science.gov (United States)

    Gordiz, Kiarash; Henry, Asegun

    Until now, our entire understanding of interfacial heat transfer has been based on the phonon gas model and Landauer formalism. Based on this framework, it is difficult to offer any intuition on heat transfer between two solid materials if one side of the interface is an amorphous structure. Here, using the interface conductance modal analysis (ICMA) method, we investigate the modal contributions to thermal interface conductance (TIC) through crystalline (c) and amorphous (a) Si/Ge interfaces. It is revealed that around 15% of the conductance through the cSi/cGe interface arises from less than 0.1% of the modes of vibration in the structure that exist between 12-13THz and because of their large eigenvectors around the interface are classified as interfacial modes. Correlation maps show that these interfacial modes exhibit strong correlations with all the other modes. The physics behind this strong coupling ability is studied by calculating the mode-level harmonic and anharmonic energy distribution among all the atoms in the system. It is found that these interfacial modes are enabled by the large degree of anharmonicity near the interface, which is higher than the bulk and ultimately allows this small group of modes to couple to other modes of vibration. In addition, unlike the cSi/cGe, correlation maps for aSi/cGe, cSi/aGe, and aSi/aGe interfaces show that the majority of contributions to TIC arise from auto-correlations instead of cross-correlations. The provided analysis sheds light on the nature of localized vibrations at interfaces and can be enlightening for other investigations of localization.

  14. Effect of doping and stoichiometric profile on transport in SiGe heterojunction bipolar transistor

    Science.gov (United States)

    Halilov, S.

    2016-09-01

    Based on analytical consideration and numerical simulations, it is shown how the mutually adjusted doping and stoichiometric profile results in improved frequency response and current gain in Si1-x Ge x -based heterojunction bipolar transistor. The closed-form expressions are derived for the dopant distribution within a certain mobility model which is parametrized in terms of the impurity concentration and stoichiometric grading on the same footing. With proper parametrization of the mobility, the method is suitable in both limits of high alloy scattering/low crystal ordering and low alloy scattering/highly ordered stoichiometrically graded structure. The work is corroborated by device simulations of a single-side HBT 30% stoichiometrically graded base, with detailed IV-curve, Gummel and AC analysis. It is shown that the distinct impurity distribution results in a reduced space-charge region, contributes to an effective electric field assisting the diffusion of the minority carriers and results in the saturation current density increased by 50%, the AC gain increased by 90%, the four-fold increase of the DC current gain, and improves the transition frequency from 274 to 358 GHz as compared to the case of the uniformly distributed acceptors. The obtained results may serve as a practical guide in design of highly-graded heterojunction bipolar transistors with efficient frequency response, high gain and enhanced power.

  15. 70 °C synthesis of high-Sn content (25%) GeSn on insulator by Sn-induced crystallization of amorphous Ge

    Energy Technology Data Exchange (ETDEWEB)

    Toko, K., E-mail: toko@bk.tsukuba.ac.jp; Oya, N.; Suemasu, T. [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Saitoh, N.; Yoshizawa, N. [Electron Microscope Facility, TIA, AIST, 16-1 Onogawa, Tsukuba 305-8569 (Japan)

    2015-02-23

    Polycrystalline GeSn thin films are fabricated on insulating substrates at low temperatures by using Sn-induced crystallization of amorphous Ge (a-Ge). The Sn layer stacked on the a-Ge layer (100-nm thickness each) had two roles: lowering the crystallization temperature of a-Ge and composing GeSn. Slow annealing at an extremely low temperature of 70 °C allowed for a large-grained (350 nm) GeSn layer with a lattice constant of 0.590 nm, corresponding to a Sn composition exceeding 25%. The present investigation paves the way for advanced electronic optical devices integrated on a flexible plastic substrate as well as on a Si platform.

  16. Atomic mobility in the overheated amorphous GeTe compound for phase change memories

    Energy Technology Data Exchange (ETDEWEB)

    Sosso, G.C. [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via R. Cozzi 55, 20125 Milano (Italy); Thomas Young Centre and Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); London Centre for Nanotechnology, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Behler, J. [Lehrstuhl fuer Theoretische Chemie, Ruhr-Universitaet Bochum, Universitaetsstrasse 150, 44780 Bochum (Germany); Bernasconi, M. [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via R. Cozzi 55, 20125 Milano (Italy)

    2016-02-15

    Abstractauthoren Phase change memories rest on the ability of some chalcogenide alloys to undergo a fast and reversible transition between the crystalline and amorphous phases upon Joule heating. The fast crystallization is due to a high nucleation rate and a large crystal growth velocity which are actually possible thanks to the fragility of the supercooled liquid that allows for the persistence of a high atomic mobility at high supercooling where the thermodynamical driving force for crystallization is also high. Since crystallization in the devices occurs by rapidly heating the amorphous phase, hysteretic effects might arise with a different diffusion coefficient and viscosity on heating than on cooling. In this work, we have quantified these hysteretic effects in the phase change compound GeTe by means of molecular dynamics simulations. The atomic mobility in the overheated amorphous phase is lower than in supercooled liquid at the same temperature and the viscosity is consequently higher. Still, the simulations of the overheated amorphous phase reveal a breakdown of the Stokes-Einstein relation between the diffusion coefficient and the viscosity, similarly to what we found previously in the supercooled liquid. Evidences are provided that the breakdown is due to the emergence of dynamical heterogeneities at high supercooling. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Structural change upon annealing of amorphous GeSbTe grown on Si(111)

    Energy Technology Data Exchange (ETDEWEB)

    Bragaglia, V., E-mail: bragaglia@pdi-berlin.de; Jenichen, B.; Giussani, A.; Perumal, K.; Riechert, H.; Calarco, R. [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2014-08-07

    The structural change upon annealing of an amorphous GeSbTe (GST) film deposited by molecular beam epitaxy on a Si(111) substrate is studied by means of X-ray diffraction (XRD), X-ray reflectivity (XRR), and atomic force microscopy (AFM). XRD profiles reveal that both metastable cubic and stable hexagonal phases are obtained with a single out-of-plane orientation. XRR study shows a density increase and consequent thickness decrease upon annealing, in accordance with literature. From both, the XRD and the AFM study, it emerges that the crystalline substrate acts as a template for the film, favoring the crystallization of the amorphous GST into the [111] oriented metastable cubic phase, and the latter turns into the [0001] stable hexagonal phase for higher annealing temperature.

  18. Structural change upon annealing of amorphous GeSbTe grown on Si(111)

    Science.gov (United States)

    Bragaglia, V.; Jenichen, B.; Giussani, A.; Perumal, K.; Riechert, H.; Calarco, R.

    2014-08-01

    The structural change upon annealing of an amorphous GeSbTe (GST) film deposited by molecular beam epitaxy on a Si(111) substrate is studied by means of X-ray diffraction (XRD), X-ray reflectivity (XRR), and atomic force microscopy (AFM). XRD profiles reveal that both metastable cubic and stable hexagonal phases are obtained with a single out-of-plane orientation. XRR study shows a density increase and consequent thickness decrease upon annealing, in accordance with literature. From both, the XRD and the AFM study, it emerges that the crystalline substrate acts as a template for the film, favoring the crystallization of the amorphous GST into the [111] oriented metastable cubic phase, and the latter turns into the [0001] stable hexagonal phase for higher annealing temperature.

  19. Nanoscale order and crystallization in nitrogen-alloyed amorphous GeTe

    Energy Technology Data Exchange (ETDEWEB)

    Darmawikarta, Kristof; Abelson, John R., E-mail: abelson@illinois.edu [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, Illinois 61801 (United States); Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, 1308 W. Main St., Urbana, Illinois 61801 (United States); Raoux, Simone [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Route 134, Yorktown Heights, New York 10598 (United States); Bishop, Stephen G. [Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, 1308 W. Main St., Urbana, Illinois 61801 (United States); Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 1406 W. Green St., Urbana, Illinois 61801 (United States)

    2014-11-10

    The nanoscale order in amorphous GeTe thin films is measured using fluctuation transmission electron microscopy (FTEM). The order increases upon annealing at 145 °C, which indicates a coarsening of subcritical nuclei. This correlates with a reduction in the nucleation delay time in laser crystallization. A shift in the FTEM peak positions may indicate a transformation in local bonding. In samples alloyed with 12 at. % nitrogen, the order does not change upon annealing, the peak does not shift, and the nucleation time is longer. The FTEM data indicate that nitrogen suppresses the structural evolution necessary for the nucleation process and increases the thermal stability of the material.

  20. Short Range Order Signature in Crystalline and Amorphous GeSbTe Xanes Spectra

    Science.gov (United States)

    Raty, Jean-Yves; Otjacques, C. Éline; Pekoz, Rengin; Bichara, Christophe; Lordi, Vince

    2011-03-01

    A new implementation of XANES spectra calculations within DFT and PAW potentials is used to compute the XANES spectra of various amorphous and crystalline GeSbTe structures. A clear correlation between the local order, either tetrahedral or distorted octahedral, and the shape of the XANES signal is observed. These calculations provide a new interpretation of past XANES measurements, relating essentially the phase change mechanism to a moderate modification of the local environment of the Ge atoms. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work was supported by the Belgian PAI 3/42 program and the FNRS-FRFC.

  1. Impact of defect occupation on conduction in amorphous Ge2Sb2Te5

    Science.gov (United States)

    Kaes, Matthias; Salinga, Martin

    2016-08-01

    Storage concepts employing the resistance of phase-change memory (PRAM) have matured in recent years. Attempts to model the conduction in the amorphous state of phase-change materials dominating the resistance of PRAM devices commonly invoke a connection to the electronic density-of-states (DoS) of the active material in form of a “distance between trap states s”. Here, we point out that s depends on the occupation of defects and hence on temperature. To verify this, we numerically study how the occupation in the DoS of Ge2Sb2Te5 is affected by changes of temperature and illumination. Employing a charge-transport model based on the Poole-Frenkel effect, we correlate these changes to the field- and temperature-dependent current-voltage characteristics of lateral devices of amorphous Ge2Sb2Te5, measured in darkness and under illumination. In agreement with our calculations, we find a pronounced temperature-dependence of s. As the device-current depends exponentially on the value of s, accounting for its temperature-dependence has profound impact on device modeling.

  2. Substrate bias effects on collector resistance in SiGe heterojunction bipolar transistors on thin film silicon-on-insulator

    Institute of Scientific and Technical Information of China (English)

    Xu Xiao-Bo; Zhang He-Ming; Hu Hui-Yong; Qu Jiang-Tao

    2011-01-01

    An analytical expression for the collector resistance of a novel vertical SiGe heteroj unction bipolar transistor (HBT)on thin film silicon-on-insulator (SOI) is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μm millimeter-wave SiGe SOI BiCMOS devices.

  3. Charge storage characteristics and tunneling mechanism of amorphous Ge-doped HfO{sub x} films

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, X.Y.; Zhang, S.Y.; Zhang, T.; Wang, R.X.; Li, L.T.; Zhang, Y. [Southwest University, School of Physical Science and Technology, Chongqing (China); Dai, J.Y. [The Hong Kong Polytechnic University, Department of Applied Physics, Hong Kong (China)

    2016-09-15

    Amorphous Ge-doped HfO{sub x} films have been deposited on p-Si(100) substrates by means of RF magnetron sputtering. Microstructural investigations reveal the partial oxidation of doped Ge atoms in the amorphous HfO{sub x} matrix and the existence of HfSiO{sub x} interfacial layer. Capacitance-voltage hysteresis of the Ag-/Ge-doped HfO{sub x}/Si/Ag memory capacitor exhibits a memory window of 3.15 V which can maintain for >5 x 10{sup 4} cycles. Current-voltage characteristics reveal that Poole-Frenkel tunneling is responsible for electron transport in the Ge-doped HfO{sub x} film. (orig.)

  4. Thermomechanical Analysis on the Phase Stability of Nitrogen-Doped Amorphous Ge2Sb2Te5 Films

    Science.gov (United States)

    Park, Il-Mok; Cho, Ju-Young; Yang, Tae-Youl; Park, Eun Soo; Joo, Young-Chang

    2011-06-01

    The phase stability of amorphous Ge2Sb2Te5 (GST) films affects the performance and reliability of phase change memory (PRAM) devices. The viscosity and the glass forming ability of nitrogen (N)-doped amorphous GST films were investigated in terms of thermomechanical behavior using wafer curvature measurements. The viscosity which increased by two orders of magnitude was observed in the N-doped amorphous GST film by measuring the stress relaxation accompanied by bimolecular structural relaxation. The glass forming ability (ΔTx), difference between the glass transition temperature (Tg) and the crystallization temperature (Tc), of GST increased as the nitrogen contents increased. These increases in the viscosity and ΔTx indicate the retardation of atomic diffusion in amorphous GST and the stabilization of the amorphous phase.

  5. Amorphous GeOx-Coated Reduced Graphene Oxide Balls with Sandwich Structure for Long-Life Lithium-Ion Batteries.

    Science.gov (United States)

    Choi, Seung Ho; Jung, Kyeong Youl; Kang, Yun Chan

    2015-07-01

    Amorphous GeOx-coated reduced graphene oxide (rGO) balls with sandwich structure are prepared via a spray-pyrolysis process using polystyrene (PS) nanobeads as sacrificial templates. This sandwich structure is formed by uniformly coating the exterior and interior of few-layer rGO with amorphous GeOx layers. X-ray photoelectron spectroscopy analysis reveals a Ge:O stoichiometry ratio of 1:1.7. The amorphous GeOx-coated rGO balls with sandwich structure have low charge-transfer resistance and fast Li(+)-ion diffusion rate. For example, at a current density of 2 A g(-1), the GeOx-coated rGO balls with sandwich and filled structures and the commercial GeO2 powders exhibit initial charge capacities of 795, 651, and 634 mA h g(-1), respectively; the corresponding 700th-cycle charge capacities are 758, 579, and 361 mA h g(-1). In addition, at a current density of 5 A g(-1), the rGO balls with sandwich structure have a 1600th-cycle reversible charge capacity of 629 mA h g(-1) and a corresponding capacity retention of 90.7%, as measured from the maximum reversible capacity at the 100th cycle.

  6. Long-Term Reliability of High Speed SiGe/Si Heterojunction Bipolar Transistors

    Science.gov (United States)

    Ponchak, George E. (Technical Monitor); Bhattacharya, Pallab

    2003-01-01

    Accelerated lifetime tests were performed on double-mesa structure Si/Si0.7Ge0.3/Si npn heterojunction bipolar transistors, grown by molecular beam epitaxy, in the temperature range of 175C-275C. Both single- and multiple finger transistors were tested. The single-finger transistors (with 5x20 micron sq m emitter area) have DC current gains approximately 40-50 and f(sub T) and f(sub MAX) of up to 22 GHz and 25 GHz, respectively. The multiple finger transistors (1.4 micron finger width, 9 emitter fingers with total emitter area of 403 micron sq m) have similar DC current gain but f(sub T) of 50 GHz. It is found that a gradual degradation in these devices is caused by the recombination enhanced impurity diffusion (REID) of boron atoms from the p-type base region and the associated formation of parasitic energy barriers to electron transport from the emitter to collector layers. This REID has been quantitatively modeled and explained, to the first order of approximation, and the agreement with the measured data is good. The mean time to failure (MTTF) of the devices at room temperature is estimated from the extrapolation of the Arrhenius plots of device lifetime versus reciprocal temperature. The results of the reliability tests offer valuable feedback for SiGe heterostructure design in order to improve the long-term reliability of the devices and circuits made with them. Hot electron induced degradation of the base-emitter junction was also observed during the accelerated lifetime testing. In order to improve the HBT reliability endangered by the hot electrons, deuterium sintered techniques have been proposed. The preliminary results from this study show that a deuterium-sintered HBT is, indeed, more resistant to hot-electron induced base-emitter junction degradation. SiGe/Si based amplifier circuits were also subjected to lifetime testing and we extrapolate MTTF is approximately 1.1_10(exp 6) hours at 125iC junction temperature from the circuit lifetime data.

  7. Thermal stability improvement of a multiple finger power SiGe heterojunction bipolar transistor under different power dissipations using non-uniform finger spacing

    Institute of Scientific and Technical Information of China (English)

    Chen Liang; Zhang Wan-Rong; Jin Dong-Yue; Shen Pei; Xie Hong-Yun; Ding Chun-Bao; Xiaa Ying; Sun Bo-Tao; Wang Ren-Qing

    2011-01-01

    method of non-uniform finger spacing is proposed to enhance thermal stability of a multiple finger power SiGe hererojunction bipolar transistor under different power dissipations. Temperature distribution on the emitter fingers of a multi-finger SiGe heterojunction bipolar transistor is studied using a numerical electro-thermal model. The results show that the SiGe heterojunction bipolar transistor with non-uniform finger spacing has a small temperature difference between fingers compared with a traditional uniform finger spacing heterojunction bipolar transistor at the same power dissipation. What is most important is that the ability to improve temperature non-uniformity is not weakened as power dissipation increases. So the method of non-uniform finger spacing is very effective in enhancing the thermal stability and the power handing capability of power device. Experimental results verify our conclusious.

  8. High quality, giant crystalline-Ge stripes on insulating substrate by rapid-thermal-annealing of Sn-doped amorphous-Ge in solid-liquid coexisting region

    Directory of Open Access Journals (Sweden)

    Ryo Matsumura

    2015-06-01

    Full Text Available Formation of large-grain (≥30 μm Ge crystals on insulating substrates is strongly desired to achieve high-speed thin-film transistors. For this purpose, we propose the methods of Sn-doping into amorphous-Ge combined with rapid-thermal-annealing (RTA in the solid-liquid coexisting temperature region for the Ge-Sn alloy system. The densities of micro-crystal-nuclei formed in this temperature region become low by tuning the RTA temperature close to the liquidus curve, which enhances the lateral growth of GeSn. Thanks to the very small segregation coefficient of Sn, almost all Sn atoms segregate toward edges of the stripes during growth. Agglomeration of GeSn degrades the surface morphologies; however, it is significantly improved by lowering the initial Sn concentration. As a result, pure Ge with large crystal grains (∼40 μm with smooth surface are obtained by optimizing the initial Sn concentration as low as 3 ∼ 5%. Lateral growth lengths are further increased through decreasing the number of nuclei in stripes by narrowing stripe width. In this way, high-crystallinity giant Ge crystals (∼200 μm are obtained for the stripe width of 3 μm. This “Si-seed free” technique for formation of large-grain pure Ge crystals is very useful to realize high-performance thin-film devices on insulator.

  9. High quality, giant crystalline-Ge stripes on insulating substrate by rapid-thermal-annealing of Sn-doped amorphous-Ge in solid-liquid coexisting region

    Science.gov (United States)

    Matsumura, Ryo; Kai, Yuki; Chikita, Hironori; Sadoh, Taizoh; Miyao, Masanobu

    2015-06-01

    Formation of large-grain (≥30 μm) Ge crystals on insulating substrates is strongly desired to achieve high-speed thin-film transistors. For this purpose, we propose the methods of Sn-doping into amorphous-Ge combined with rapid-thermal-annealing (RTA) in the solid-liquid coexisting temperature region for the Ge-Sn alloy system. The densities of micro-crystal-nuclei formed in this temperature region become low by tuning the RTA temperature close to the liquidus curve, which enhances the lateral growth of GeSn. Thanks to the very small segregation coefficient of Sn, almost all Sn atoms segregate toward edges of the stripes during growth. Agglomeration of GeSn degrades the surface morphologies; however, it is significantly improved by lowering the initial Sn concentration. As a result, pure Ge with large crystal grains (˜40 μm) with smooth surface are obtained by optimizing the initial Sn concentration as low as 3 ˜ 5%. Lateral growth lengths are further increased through decreasing the number of nuclei in stripes by narrowing stripe width. In this way, high-crystallinity giant Ge crystals (˜200 μm) are obtained for the stripe width of 3 μm. This "Si-seed free" technique for formation of large-grain pure Ge crystals is very useful to realize high-performance thin-film devices on insulator.

  10. Dislocation-templated amorphization of Ge2Sb2Te5 nanowires under electric pulses: A theoretical model

    Science.gov (United States)

    Ji, Xiang-Ying; Feng, Xi-Qiao

    2013-06-01

    Owing to their unique phase change property, GeSbTe alloys hold promise for applications as a candidate material for nonvolatile electronic data storage. In this paper, we theoretically investigate the dislocation mechanisms underlying the phase change phenomenon of GeSbTe alloys under electric pulses. On the basis of the recent experiments by Nam et al. (Science 336, 1561-1566 (2012)), a theoretical model is presented to rationalize the dislocation-templated amorphization process under the action of electric pulses. The physical mechanisms of the nucleation, movement, and multiplication of dislocations in the electric field are analyzed. Using the model, the evolutions of temperature and dislocation density in a Ge2Sb2Te5 nanowire under electric pulses are computed and the critical voltage of amorphization is predicted.

  11. Application of photo-doping phenomenon in amorphous chalcogenide GeS2 film to optical device

    Science.gov (United States)

    Murakami, Yoshihisa; Arai, Katsuya; Wakaki, Moriaki; Shibuya, Takehisa; Shintaku, Toshihiro

    2015-03-01

    Photodoping phenomenon is observed when a double-layer consisting of an amorphous chalcogenide film (As2S3, GeS2, GeSe2 etc.) and a metal (Ag, Cu etc.) film is illuminated by light. The metal diffuses abnormally into the amorphous chalcogenide layer. Amorphous chalcogenide films of GeS2 with an Ag over layer exhibited large increase of refractive index through the abnormal doping of Ag by irradiating the light around the absorption edge of the GeS2 chalcogenide. In this study, we aimed the application of this effect for the fabrication of optical devices and fabricated various micro doped patterns by using a laser beam. Mask less pattering with refractive index modified films are possible by manipulating the scanning of the laser beam. Micro gratings were fabricated using a confocal laser microscope to work as both fabrication and observation system. Waveguides were also fabricated by scanning the laser beam for photodoping. Holographic gratings were fabricated by utilizing the photodoping of the two beam interference pattern, which showed the possibility to produce large scale optical devices or mass production.

  12. Effect of ion irradiation on the stability of amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} thin films

    Energy Technology Data Exchange (ETDEWEB)

    De Bastiani, R. [Dipartimento di Fisica e Astronomia, Universita di Catania and MATIS CNR-INFM, Via S. Sofia 64, I-95123 Catania (Italy)], E-mail: riccardo.debastiani@ct.infn.it; Piro, A.M.; Crupi, I.; Grimaldi, M.G. [Dipartimento di Fisica e Astronomia, Universita di Catania and MATIS CNR-INFM, Via S. Sofia 64, I-95123 Catania (Italy); Rimini, E. [Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Stradale Primosole 50, I-95121 Catania (Italy)

    2008-05-15

    The archival life of phase-change memories (PCM) is determined by the thermal stability of amorphous phase in a crystalline matrix. In this paper, we report the effect of ion beam irradiation on the crystallization kinetics of amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} alloy (GST). The transition rate of amorphous GST films was measured by in situ time resolved reflectivity (TRR). The amorphous to crystal transformation time decreases considerably in irradiated amorphous GST samples when ion fluence increases. The stability of amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} thin films subjected to ion irradiation is discussed in terms of the free energy variation of the amorphous state because of damage accumulation.

  13. An Analytical Avalanche Multiplication Model for Partially Depleted Silicon-on-Insulator SiGe Heterojunction Bipolar Transistors

    Institute of Scientific and Technical Information of China (English)

    XU Xiao-Bo; ZHANG He-Ming

    2011-01-01

    An analytical expression for avalanche multiplication of a novel vertical SiGe partially depleted heterojunction bipolar transistor (HBT) on a thin silicon-on-insulator (SOI) layer is obtained,considering vertical and horizontal impact ionization effects.The avalanche multiplication is found to be dependent on the collector width and doping concentration,and shows kinks with the increase of reverse base-collector bias,which is quite different from that of a conventional bulk HBT.The model is consistent with the experimental and simulation data and is found to be significant for the design and simulation of 0.13μm millimeter wave SiGe SOI BiCMOS technology.

  14. Ultrafast sub-threshold photo-induced response in crystalline and amorphous GeSbTe thin films

    Science.gov (United States)

    Shu, M. J.; Chatzakis, I.; Kuo, Y.; Zalden, P.; Lindenberg, A. M.

    2013-05-01

    Pump-probe optical reflectivity and terahertz transmission measurements have been used to investigate time resolved sub-threshold photo-induced effects in crystalline and amorphous GeSbTe films at MHz repetition rates. The reflectivity in both phases exhibits long-lived modulations consistent with the sign of the changes that occur upon switching but of smaller magnitude. These can be understood by the generation of acoustic strains with the crystalline phase response dominated by thermal effects and the amorphous phase response associated with electronically induced changes. Evidence for a photo-induced distortion is observed in the amorphous phase which develops homogeneously within the excited region on few-picosecond time scales.

  15. Microscopic origin of resistance drift in the amorphous state of the phase-change compound GeTe

    Science.gov (United States)

    Gabardi, S.; Caravati, S.; Sosso, G. C.; Behler, J.; Bernasconi, M.

    2015-08-01

    Aging is a common feature of the glassy state. In the case of phase-change chalcogenide alloys the aging of the amorphous state is responsible for an increase of the electrical resistance with time. This phenomenon called drift is detrimental in the application of these materials in phase-change nonvolatile memories, which are emerging as promising candidates for storage class memories. By means of combined molecular dynamics and electronic structure calculations based on density functional theory, we have unraveled the atomistic origin of the resistance drift in the prototypical phase-change compound GeTe. The drift results from a widening of the band gap and a reduction of Urbach tails due to structural relaxations leading to the removal of chains of Ge-Ge homopolar bonds. The same structural features are actually responsible for the high mobility above the glass transition which boosts the crystallization speed exploited in the device.

  16. Indium (In)- and tin (Sn)-based metal induced crystallization (MIC) on amorphous germanium (α-Ge)

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Dong-Ho; Park, Jin-Hong, E-mail: jhpark9@skku.edu

    2014-12-15

    Highlights: • In- and Sn-based MIC phenomenon on amorphous (α)-Ge is newly reported. • The In- and Sn-MIC phenomenon respectively started at 250 °C and 400 °C. • The Sn-MIC process presents higher sheet resistance and bigger crystal grains. - Abstract: In this paper, metal-induced crystallization (MIC) phenomenon on α-Ge by indium (In) and tin (Sn) are thoroughly investigated. In- and Sn-MIC process respectively started at 250 °C and 400 °C. Compared to the previously reported MIC samples including In-MIC, Sn-MIC process presented higher sheet resistance (similar to that of SPC) and bigger crystal grains above 50 nm (slightly smaller than that of SPC). According to SIMS analysis, Sn atoms diffused more slowly into Ge than In at 400 °C, providing lower density of heterogeneous nuclei induced by metals and consequently larger crystal grains.

  17. Thermal conductivity of carbon doped GeTe thin films in amorphous and crystalline state measured by modulated photo thermal radiometry

    Science.gov (United States)

    Kusiak, Andrzej; Battaglia, Jean-Luc; Noé, Pierre; Sousa, Véronique; Fillot, F.

    2016-09-01

    The thermal conductivity and thermal boundary resistance of GeTe and carbon doped GeTe thin films, designed for phase change memory (PCM) applications, were investigated by modulated photo thermal radiometry. It was found that C doping has no significant effect on the thermal conductivity of these chalcogenides in amorphous state. The thermal boundary resistance between the amorphous films and SiO2 substrate is also not affected by C doping. The films were then crystallized by an annealing at 450°C as confirmed by optical reflectivity analysis. The thermal conductivity of non-doped GeTe significantly increases after crystallization annealing. But, surprisingly the thermal conductivity of the crystallized C doped GeTe was found to be similar from that of the amorphous state and independent of C concentration. As for the amorphous phase, C doping does not affect the thermal boundary resistance between the crystalline GeTe films and SiO2 substrate. This behaviour is discussed thanks to XRD and FTIR analysis. In particular, XRD shows a decrease of crystalline grain size in crystalline films as C concentration is increased. FTIR analysis of the film before and after crystallization evidenced that this evolution could be attributed to the disappearing of Ge-C bonds and migration of C atoms out of the GeTe phase upon crystallization, limiting then the growth of GeTe crystallites in C-doped films.

  18. First- and second-order electrical modelling and experiment on very high speed SiGeC heterojunction bipolar transistors

    Science.gov (United States)

    Nunez-Perez, José Cruz; Lakhdara, Maya; Bouhouche, Manel; Verdier, Jacques; Latreche, Saïda; Gontrand, Christian

    2009-04-01

    We present in this paper an electrical study centred on NPN heterojunction bipolar transistors (HBTs), realized in an industrial BiCMOS SiGe:C process, featuring high attractive performances (ft > 200 GHz) in terms of microwave behaviour and low-frequency noise; reaching this level of performance with good dc characteristics could be however a difficult challenge. Electrical modelling is investigated, using our 2D simulator, based on the drift-diffusion model (DDM). The simulations were very efficient for optimizing the devices. The dc and ac results obtained in this work are efficiently compared with electrical characteristics coming from measurements and SPICE-like parameter extractions, from simulations via a compact model (HICUM) implemented in the so-called commercial simulator ADS (advanced design system). This work was a first step for designing RF circuits like oscillators in a simple way.

  19. Two-zone SiGe base heterojunction bipolar charge plasma transistor for next generation analog and RF applications

    Science.gov (United States)

    Bramhane, Lokesh Kumar; Singh, Jawar

    2017-01-01

    For next generation terahertz applications, heterojunction bipolar transistor (HBT) with reduced dimensions and charge plasma (CP) can be a potential candidate due to simplified and inexpensive process. In this paper, a symmetric lateral two-zone SiGe base heterojunction bipolar charge plasma transistor (HBCPT) with an extruded (extended) base is proposed and its performance at circuit level is studied. The linearly graded electric field in the proposed HBCPT provides improved self gain (β) and cut-off frequency (fT). Two-dimensional (2-D) TCAD and small-signal model based simulations of the proposed HBCPT demonstrates high self gain β 35-172.93 and fT of 1-4 THz for different device parameters. Moreover, fT of 1104.9 GHz and β of 35 can be achieved by decreasing Nb up to 8.2 ×1017cm-3 . Although, fT of 2 THz and 4 THz can also be achieved by reducing the base resistance up to 10 Ω and increasing the emitter/collector length up to 63 nm, respectively. The small-signal analysis of common-emitter amplifier based on the proposed HBCPT demonstrate high voltage gain of 50.11 as compared to conventional HBT (18.1).

  20. Effect of Si interface surface roughness to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor

    Energy Technology Data Exchange (ETDEWEB)

    Hasanah, Lilik, E-mail: lilikhasanah@upi.edu; Suhendi, Endi; Tayubi, Yuyu Rahmat; Yuwono, Heru [Department of Physics Education, Universitas Pendidikan Indonesia, Jl. Setiabudhi 229 Bandung 40154 (Indonesia); Nandiyanto, Asep Bayu Dani [Department Kimia, Universitas Pendidikan Indonesia, Jl. Setiabudhi 229 Bandung 40154 (Indonesia); Murakami, Hideki [Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan); Khairrurijal [Physics of Electronic Materials Research Division, Institut Teknologi Bandung, Bandung 40132 (Indonesia)

    2016-02-08

    In this work we discuss the surface roughness of Si interface impact to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor. The Si interface surface roughness can be analyzed from electrical characteristics through the transversal electron velocity obtained as fitting parameter factor. The results showed that surface roughness increase as Ge content of virtual substrate increase This model can be used to investigate the effect of Ge content of the virtual substrate to the interface surface condition through current-voltage characteristic.

  1. Comparison of total dose effects on SiGe heterojunction bipolar transistors induced by different swift heavy ion irradiation

    Science.gov (United States)

    Sun, Ya-Bin; Fu, Jun; Xu, Jun; Wang, Yu-Dong; Zhou, Wei; Zhang, Wei; Cui, Jie; Li, Gao-Qing; Liu, Zhi-Hong

    2014-11-01

    The degradations in NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were fully studied in this work, by means of 25-MeV Si, 10-MeV Cl, 20-MeV Br, and 10-MeV Br ion irradiation, respectively. Electrical parameters such as the base current (IB), current gain (β), neutral base recombination (NBR), and Early voltage (VA) were investigated and used to evaluate the tolerance to heavy ion irradiation. Experimental results demonstrate that device degradations are indeed radiation-source-dependent, and the larger the ion nuclear energy loss is, the more the displacement damages are, and thereby the more serious the performance degradation is. The maximum degradation was observed in the transistors irradiated by 10-MeV Br. For 20-MeV and 10-MeV Br ion irradiation, an unexpected degradation in IC was observed and Early voltage decreased with increasing ion fluence, and NBR appeared to slow down at high ion fluence. The degradations in SiGe HBTs were mainly attributed to the displacement damages created by heavy ion irradiation in the transistors. The underlying physical mechanisms are analyzed and investigated in detail.

  2. Universal amorphous-amorphous transition in GexSe100-x glasses under pressure

    DEFF Research Database (Denmark)

    Yildirim, Can; Micoulaut, Matthieu; Boolchand, Punit

    2016-01-01

    –20 GPa, depending on the composition. This increase is attributed to the metallization event that can be traced with the red shift in Ge K edge energy which is also identified by the principal peak position of the structure factor. The densification mechanisms are studied in details by means of AIMD......Pressure induced structural modifications in vitreous GexSe100−x (where 10 ≤ x ≤ 25) are investigated using X-ray absorption spectroscopy (XAS) along with supplementary X-ray diffraction (XRD) experiments and ab initio molecular dynamics (AIMD) simulations. Universal changes in distances and angle...... simulations and compared to the experimental results. The evolution of bond angle distributions, interatomic distances and coordination numbers are examined and lead to similar pressure-induced structural changes for any composition....

  3. Kinetics of liquid-mediated crystallization of amorphous Ge from multi-frame dynamic transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Santala, M. K., E-mail: melissa.santala@oregonstate.edu; Campbell, G. H. [Materials Science Division, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551 (United States); Raoux, S. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany)

    2015-12-21

    The kinetics of laser-induced, liquid-mediated crystallization of amorphous Ge thin films were studied using multi-frame dynamic transmission electron microscopy (DTEM), a nanosecond-scale photo-emission transmission electron microscopy technique. In these experiments, high temperature gradients are established in thin amorphous Ge films with a 12-ns laser pulse with a Gaussian spatial profile. The hottest region at the center of the laser spot crystallizes in ∼100 ns and becomes nano-crystalline. Over the next several hundred nanoseconds crystallization continues radially outward from the nano-crystalline region forming elongated grains, some many microns long. The growth rate during the formation of these radial grains is measured with time-resolved imaging experiments. Crystal growth rates exceed 10 m/s, which are consistent with crystallization mediated by a very thin, undercooled transient liquid layer, rather than a purely solid-state transformation mechanism. The kinetics of this growth mode have been studied in detail under steady-state conditions, but here we provide a detailed study of liquid-mediated growth in high temperature gradients. Unexpectedly, the propagation rate of the crystallization front was observed to remain constant during this growth mode even when passing through large local temperature gradients, in stark contrast to other similar studies that suggested the growth rate changed dramatically. The high throughput of multi-frame DTEM provides gives a more complete picture of the role of temperature and temperature gradient on laser crystallization than previous DTEM experiments.

  4. Compositional dependence of the optical properties of amorphous semiconducting glass Ge10AsxSe(90-x) thin films

    Science.gov (United States)

    Shaaban, E. R.

    2007-03-01

    Optical properties of ternary chalcognide amorphous Ge10AsxSe(90-x) (with 10⩽x⩽25 at%) thin films prepared by thermal evaporation have been measured in visible and near-infrared spectral region. The straightforward analysis proposed by Swanepoel has been successfully employed, and it has allowed us to determine the average thickness d¯, and the refractive index, n, of the films, with high accuracy. The refractive index, n and the average thickness d¯ has been determined from the upper and lower envelopes of the transmission spectra measured at normal incidence, in the spectral range 400 2500 nm. The absorption coefficient α, and therefore extinction coefficient k, have been determined from the transmission spectra in the strong-absorption region. The dispersion of the refractive index is discussed in terms of the single oscillator Wemple DiDomenico model, and the optical absorption edge is described using the ‘nondirect transition’ model proposed by Tauc. Likewise, the optical energy gap is derived from Tauc's extrapolation. The relationship between the optical gap and chemical composition in Ge10AsxSe(90-x) amorphous system is discussed in terms of the average heat of atomization Hs and average coordination number Nc. Finally, the chemical bond approach has been also applied successfully to interpret the decrease of the glass optical gap with increasing As content.

  5. A study of the effects of the base doping profile on SiGe heterojunction bipolar transistor performance for all levels of injection

    Science.gov (United States)

    Khanduri, Gagan; Panwar, Brishbhan

    2006-04-01

    The effects of two different base doping profiles on the current gain and cut-off frequency for all levels of current injection have been studied for NPN Si/SiGe/Si double heterojunction bipolar transistors (SiGe DHBTs). The two-dimensional simulation results for a SiGe DHBT with uniform base doping and a fixed base Gummel number are compared with a non-uniform base doping profile SiGe drift-DHBT device. The study explains the performance of SiGe HBTs at different injection levels by analysing the electron and hole mobility, drift velocity, electric field, junction capacitances and intrinsic and extrinsic base region conductivities. The base doping profile in the SiGe drift-DHBT is controlled in such a way that it creates a net accelerating drift field in the quasi-neutral base for minority electrons. This accelerating field subsequently improves the current gain and cut-off frequency for the SiGe drift-DHBT in comparison with the SiGe DHBT for all levels of injection.

  6. Characterization of optical constants and dispersion parameters of highly transparent Ge20Se76Sn4 amorphous thin film

    Science.gov (United States)

    Abd-Elrahman, M. I.; Hafiz, M. M.; Abdelraheem, A. M.; Abu-Sehly, A. A.

    2015-12-01

    Amorphous chalcogenide Ge20Se76Sn4 thin films of six different thicknesses (50-350 nm) are prepared by the thermal evaporation technique. Optical transmission and reflection spectra, in the wavelength range of the incident photons from 250 to 2500 nm, are used to study the effect of the film thickness on some optical properties. It is found that the effect of film thickness leads to increase in the absorption coefficient, refractive index, extinction coefficient and the width of the tails of localized states in the gap region. The decrease in optical band gap energy with increasing the film thickness is attributed to the formation of a band tail which narrows down the band gap. Dispersion analyses of refractive index reveal a decrease in the single-oscillator energy and an increase in the dispersion energy with increase in film thickness.

  7. Reversible electrical resistance switching in GeSbTe thin films : An electrolytic approach without amorphous-crystalline phase-change

    NARCIS (Netherlands)

    Pandian, Ramanathaswamy; Kooi, Bart J.; Palasantzas, George; De Hosson, Jeff Th. M.; Wouters, DJ; Hong, S; Soss, S; Auciello, O

    2008-01-01

    Besides the well-known resistance switching originating from the amorphous-crystalline phase-change in GeSbTe thin films, we demonstrate another switching mechanism named 'polarity-dependent resistance (PDR) switching'. 'Me electrical resistance of the film switches between a low- and high-state whe

  8. Optical properties of pulsed laser deposited amorphous (GeSe2)100- x -Bi x films

    Science.gov (United States)

    Pan, R. K.; Tao, H. Z.; Zang, H. C.; Zhao, X. J.; Zhang, T. J.

    2010-06-01

    Amorphous (GeSe2)100- x -Bi x ( x=0, 0.4, 2 and 4) films were prepared by the pulsed laser deposition technique. The optical transmission spectra, absorption spectra and Raman spectra of the films were measured. The short-wavelength absorption edges in the strong absorption region of the films were described using the ‘non-direct-transition’ model proposed by Tauc and the optical band gaps (Eg^{opt}) were determined. The Urbach energy ( E u) was derived in the exponential part of the absorption edge. Both Eg^{opt} and Tauc slopes ( B 1/2) decreased with increasing Bi content, while E u had the opposite trend. The refractive indices of the films were calculated from the transmission spectra by using the Swanepoel method. Analysis of Raman spectra and absorption spectra shows that Bi addition decreases the mean bond energy and increases E u in the amorphous films, which caused the decrease of Eg^{opt}. The changes of the refractive indices are also discussed.

  9. Amorphous silicon germanium carbide photo sensitive bipolar junction transistor with a base-contact and a continuous tunable high current gain

    Energy Technology Data Exchange (ETDEWEB)

    Bablich, A., E-mail: andreas.bablich@uni-siegen.de [Department of Electrical and Computer Engineering, Institute for Microsystem Technologies, University of Siegen, Hoelderlinstrasse 3, 57076 Siegen (Germany); Merfort, C., E-mail: merfort@imt.e-technik.uni-siegen.de [Department of Electrical and Computer Engineering, Institute for Microsystem Technologies, University of Siegen, Hoelderlinstrasse 3, 57076 Siegen (Germany); Eliasz, J., E-mail: jacek.eliasz@student.uni-siegen.de [Department of Electrical and Computer Engineering, Institute for Microsystem Technologies, University of Siegen, Hoelderlinstrasse 3, 57076 Siegen (Germany); Schäfer-Eberwein, H., E-mail: heiko.schaefer@uni-siegen.de [Department of Electrical and Computer Engineering, Institute of High Frequency and Quantum Electronics, University of Siegen, Hoelderlinstrasse 3, 57076 Siegen (Germany); Haring-Bolivar, P., E-mail: peter.haring@uni-siegen.de [Department of Electrical and Computer Engineering, Institute of High Frequency and Quantum Electronics, University of Siegen, Hoelderlinstrasse 3, 57076 Siegen (Germany); Boehm, M., E-mail: markus.boehm@uni-siegen.de [Department of Electrical and Computer Engineering, Institute for Microsystem Technologies, University of Siegen, Hoelderlinstrasse 3, 57076 Siegen (Germany)

    2014-05-02

    In this paper, the design, fabrication and characterization of an amorphous silicon germanium carbide (a-SiGeC:H) photo sensitive bipolar junction transistor (PS-BJT) with three terminals are presented. Whereas the current gain of similar transistor devices presented in the past (Wu et al., 1984; Hwang et al., 1993; Nascetti and Caputo, 2002; Chang et al., 1985a,b; Wu et al, 1985; Hong et al., 1990) can only be controlled with photo induced charge generation, the n–i–δp–i–n structure developed features a contacted base to provide the opportunity to adjust the current gain optically and electrically, too. Electron microscope-, current-/voltage- and spectral measurements were performed to study the PS-BJT behavior and calculate the electrical and optical current gain. The spectral response maximum of the base–collector diode has a value of 170 mA/W applying a base–collector voltage of − 1 V and is located at 620 nm. The base–emitter diode reaches a sensitivity of 25.7 mA/W at 530 nm with a base-emitter voltage of − 3 V. The good a-Si:H transport properties are validated in a μτ-product of 4.6 × 10{sup −6} cm{sup 2} V s, which is sufficient to reach a continuous base- and photo-tunable current gain of up to − 126 at a base current of I{sub B} = + 10 nA and a collector–emitter voltage of V{sub CE} = − 3 V. The transistor obtains a maximum collector current of − 65.5 μA (V{sub CE} = − 3 V) and + 56.2 μA (V{sub CE} = + 3 V) at 10,000 lx 5300 K white-light illumination. At 3300 lx, the electrical current gain reaches a value of + 100 (V{sub CE} = + 2 V) at I{sub B} = 10 nA. With a negative base current of I{sub B} = − 10 nA the electrical gain can be adjusted between 87 (V{sub CE} = + 2 V) and − 106 (V{sub CE} = -3 V), respectively. When no base charge is applied, the transistor is “off” for V{sub CE} > − 3 V. Reducing the base current increases the electrical current gain. Operating with a voltage V{sub CE} of just ± 2 V

  10. Analytical base-collector depletion capacitance in vertical SiGe heterojunction bipolar transistors fabricated on CMOS-compatible silicon on insulator

    Institute of Scientific and Technical Information of China (English)

    Xu Xiao-Bo; Zhang He-Ming; Hu Hui-Yong; Ma Jian-Li; Xu Li-Jun

    2011-01-01

    The base-collector depletion capacitance for vertical SiGe npn heterojunction bipolar transistors (HBTs) on silicon on insulator (SOI) is split into vertical and lateral parts. This paper proposes a novel analytical depletion capacitance model of this structure for the first time. A large discrepancy is predicted when the present model is compared with the conventional depletion model, and it is shown that the capacitance decreases with the increase of the reverse collectorbase bias-and shows a kink as the reverse collector-base bias reaches the effective vertical punch-through voltage while the voltage differs with the collector doping concentrations, which is consistent with measurement results. The model can be employed for a fast evaluation of the depletion capacitance of an SOI SiGe HBT and has useful applications on the design and simulation of high performance SiGe circuits and devices.

  11. Characterization and application of a GE amorphous silicon flat panel detector in a synchrotron light source

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.H. [XSD Advanced Photon Source, Argonne National Laboratory (United States)], E-mail: jlee@aps.anl.gov; Almer, J. [XSD Advanced Photon Source, Argonne National Laboratory (United States); Aydiner, C. [Los Alamos National Laboratory (United States); Bernier, J.; Chapman, K.; Chupas, P.; Haeffner, D. [XSD Advanced Photon Source, Argonne National Laboratory (United States); Kump, K. [GE Healthcare (United States); Lee, P.L.; Lienert, U.; Miceli, A. [XSD Advanced Photon Source, Argonne National Laboratory (United States); Vera, G. [GE Healthcare (United States)

    2007-11-11

    Characterization, in the language of synchrotron radiation, was performed on a GE Revolution 41RT flat panel detector using the X-ray light source at the Advanced Photon Source (APS). The detector has an active area of 41x41 cm{sup 2} with 200x200 {mu}m{sup 2} pixel size. The nominal working photon energy is around 80 keV. Modulation transfer function (MTF) was measured in terms of line spread function (LSF) using a 25 {mu}mx1 cm tungsten slit. Memory effects of the detector elements, called lag, were also measured. The large area and fast data capturing rate -8 fps in unbinned mode, 30 fps in binned or region of interest (ROI) mode-make the GE flat panel detector a unique and very versatile detector for synchrotron experiments. In particular, we present data from pair distribution function (PDF) measurements to demonstrate the special features of this detector.

  12. Ge L{sub 3}-edge x-ray absorption near-edge structure study of structural changes accompanying conductivity drift in the amorphous phase of Ge{sub 2}Sb{sub 2}Te{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Mitrofanov, K. V. [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8562 (Japan); Kolobov, A. V., E-mail: a.kolobov@aist.go.jp; Fons, P. [Nanoelectronics Research Institute and Green Nanoelectronics Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8562, Japan and Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1, Kouto, Sayo, Hyogo 679-5198 (Japan); Wang, X.; Tominaga, J. [Nanoelectronics Research Institute and Green Nanoelectronics Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8562 (Japan); Tamenori, Y.; Uruga, T. [Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1, Kouto, Sayo, Hyogo 679-5198 (Japan); Ciocchini, N.; Ielmini, D. [DEIB - Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano (Italy)

    2014-05-07

    A gradual uncontrollable increase in the resistivity of the amorphous phase of phase-change alloys, such as Ge{sub 2}Sb{sub 2}Te{sub 5}, known as drift, is a serious technological issue for application of phase-change memory. While it has been proposed that drift is related to structural relaxation, no direct structural results have been reported so far. Here, we report the results of Ge L{sub 3}-edge x-ray absorption measurements that suggest that the drift in electrical conductivity is associated with the gradual conversion of tetrahedrally coordinated Ge sites into pyramidal sites, while the system still remains in the amorphous phase. Based on electronic configuration arguments, we propose that during this process, which is governed by the existence of lone-pair electrons, the concentration of free carriers in the system decreases resulting in an increase in resistance despite the structural relaxation towards the crystalline phase.

  13. Structure of and phase transformations in bulk amorphous (GaSb) sub 1 sub - sub x (Ge sub 2) sub x

    CERN Document Server

    Sapelkin, A V

    1997-01-01

    temperatures, under high pressures and at ambient conditions. Combined EXAFS and powder diffraction methods have been used to study the high pressure behavior of materials. The results revealed a complex picture of structural transformations in (GaSb) sub 1 sub - sub x (Ge sub 2) sub x owing to the meta-stable nature of samples. The semiconductor-to-metal transition observed previously is found to be due to percolation through the high pressure metallic phase GaSb II. It is showed that the combination of two structural techniques, powder diffraction and EXAFS, can provide quite detailed information on the structural behavior of amorphous materials under high pressures. The temperature-dependent EXAFS studies showed that semiconducting amorphous GaSb is likely to be chemically ordered. Issues concerning determination of the structure of amorphous materials and information theory are widely discussed. Amorphous materials are not new to scientists and mankind -- man has been using glass and glassy materials for ...

  14. Physical and optical properties of amorphous Ge x As20S80- x thin films

    Science.gov (United States)

    Dahshan, A.; Amer, H. H.

    2011-02-01

    We report the effect of replacement of sulfur by germanium on the optical constants and some other physical parameters of chalcogenide Ge x As20S80- x (where x = 0, 5, 10, 15 and 20 at%) thin films. Increasing germanium content affected the average heat of atomization, average coordination number, number of constraints and the cohesive energy. Films with thicknesses 800-820 nm of Ge x As20S80- x were prepared by thermal evaporation of bulk samples. Transmission spectra, T(λ), of the films at normal incidence were obtained in the region from 400 to 2500 nm. A straightforward analysis proposed by Swanepoel [J. Phys. E Sci. Instrum. 16 (1983) p 1214], based on the use of maxima and minima of the interference fringes, has been applied to derive the real and imaginary parts of the complex index of refraction and also the film thickness. Optical absorption measurements showed that the fundamental absorption edge is a function of composition. Optical absorption is due to allowed non-direct transition and the energy gap decreases while the refractive index increases with increasing germanium content. The chemical-bond approach has been applied to obtain the excess of S-S homopolar bonds and the cohesive energy of the Ge x As20S80- x system.

  15. Effects of dopants on the amorphous-to-fcc transition in Ge{sub 2}Sb{sub 2}Te{sub 5} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Privitera, S. [R and D Department, Micro, Power, Analog (MPA) Group, STMicroelectronics, MP8, Stradale Primosole 50, 95121 Catania (Italy)]. E-mail: stefania.privitera@st.com; Rimini, E. [Istituto di Microelettronica e Microsistemi (IMM), Consiglio Nazionale delle Ricerche (CNR), Stradale Primosole 50, 95121 Catania (Italy); Bongiorno, C. [Istituto di Microelettronica e Microsistemi (IMM), Consiglio Nazionale delle Ricerche (CNR), Stradale Primosole 50, 95121 Catania (Italy); Pirovano, A. [FTM, Advanced R and D, NVMTD, STMicroelectronics, Via Olivetti 2, 20041, Agrate Brianza (Italy); Bez, R. [FTM, Advanced R and D, NVMTD, STMicroelectronics, Via Olivetti 2, 20041, Agrate Brianza (Italy)

    2007-04-15

    The amorphous-to-crystal transition has been studied through in situ resistance measurements in Ge{sub 2}Sb{sub 2}Te{sub 5} thin films doped by ion implantation with nitrogen, oxygen or fluorine at different concentrations. Enhancement of the thermal stability has been observed in O and N amorphous doped Ge{sub 2}Sb{sub 2}Te{sub 5}. Larger effects have been found in the case of nitrogen doping. On the contrary, doping with Fluorine produced a decrease in the crystallization temperature. The electrical properties have been related to the structural phase change through in situ transmission electron microscopy analysis. The comparison between undoped and doped Ge{sub 2}Sb{sub 2}Te{sub 5} shows that the introduction of oxygen or nitrogen modifies in a different way the kinetics of the amorphous-to-fcc transition and gives new insight on the effects of doping with light elements in GeSbTe alloys.

  16. X-ray photoelectron spectroscopy studies of Ag-doped thin amorphous Ge{sub x}Sb{sub 40-x}S{sub 60} films

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, R.K.; Fitzgerald, A.G.; Christova, K

    2002-12-30

    X-ray photoelectron spectroscopy has been used to determine the binding energies of the core electrons in Ag-doped amorphous thin Ge{sub x}Sb{sub 40-x}S{sub 60} films (x=15, 20, 25 and 27). Chemical shifts of the constituent elements have revealed that electrons are transferred from chalcogenide to metal and compounds such as Ag{sub 2}S and Ag{sub 2}O are likely to foue to photo-induced chemical modification and oxidation, respectively. Charge defects are induced in the amorphous system.

  17. Mechanically and thermally stable Si-Ge films and heterojunction bipolar transistors grown by rapid thermal chemical vapor deposition at 900 °C

    Science.gov (United States)

    Green, M. L.; Weir, B. E.; Brasen, D.; Hsieh, Y. F.; Higashi, G.; Feygenson, A.; Feldman, L. C.; Headrick, R. L.

    1991-01-01

    Traditional techniques for growing Si-Ge layers have centered around low-temperature growth methods such as molecular-beam epitaxy and ultrahigh vacuum chemical vapor deposition in order to achieve strain metastability and good growth control. Recognizing that metastable films are probably undesirable in state-of-the-art devices on the basis of reliability considerations, and that in general, crystal perfection increases with increasing deposition temperatures, we have grown mechanically stable Si-Ge films (i.e., films whose composition and thickness places them on or below the Matthews-Blakeslee mechanical equilibrium curve) at 900 °C by rapid thermal chemical vapor deposition. Although this limits the thickness and the Ge composition range, such films are exactly those required for high-speed heterojunction bipolar transistors and Si/Si-Ge superlattices, for example. The 900 °C films contain three orders of magnitude less oxygen than their limited reaction processing counterparts grown at 625 °C. The films are thermally stable as well, and do not interdiffuse more than about 20 Å after 950 °C for 20 min. Therefore, they can be processed with standard Si techniques. At 900 °C, the films exhibit growth rates of about 15-20 Å/s. We have also demonstrated the growth of graded layers of Si-Ge, and have determined that a strain gradient exists in these layers.

  18. Preferred orientation of nanoscale order at the surface of amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} films

    Energy Technology Data Exchange (ETDEWEB)

    Tony Li, Tian; Abelson, John R. [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, Illinois 61801 (United States); Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, 1308 W. Main St., Urbana, Illinois 61801 (United States); Hoon Lee, Tae; Elliott, Stephen R. [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2013-11-11

    We report evidence that as-deposited amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} thin films contain nanoscale clusters that exhibit a preferred orientation, attributed to the earliest stages of heterogeneous nucleation. Fluctuation transmission electron microscopy reveals structural order in the samples, but (220)-related contributions are suppressed. When homogeneous nucleation is promoted via electron bombardment, the sample remains diffraction amorphous but the (220) contribution appears. We simulated data for randomly oriented nanoscale order using ab initio molecular-dynamics models of Ge{sub 2}Sb{sub 2}Te{sub 5}. The simulated (220) contribution always has larger magnitude than higher-order signals; thus, the lack of the experimental signal indicates a significant preferred orientation.

  19. Effect of Sb addition on linear and non-linear optical properties of amorphous Ge-Se-Sn thin films

    Science.gov (United States)

    Sharma, Navjeet; Sharma, Surbhi; Sarin, Amit; Kumar, Rajesh

    2016-01-01

    Optical characterization of amorphous thin films of Ge20Sn10Se70-xSbx (x = 0, 3, 6, 9, 12, 15) has been carried out. Thin films were deposited onto pre cleaned glass substrates using thermal evaporation technique. Transmission spectra of the films were recorded, for normal incidence, in range 400-2400 nm. Refractive index of the films was calculated using the envelope method by Swanepoel. Dispersion analysis has been carried out using single effective oscillator model. Other optical constants such as absorption coefficients, extinction coefficients have also been evaluated. Tauc plots were used to evaluate the optical band gap. The refractive index has been found to be increasing while the band gap decreases with increasing Sb concentration. The observed optical behavior of the films has been explained using chemical bond approach. Cohesive energy is found to be decreasing in the present work, which reflects that bond strength decreases with the increasing content of Sb. Non-linear optical parameters (i.e. n2 and χ(3)) have been derived from linear optical parameters (i.e. n, k, Eg). Observed changes in linear and non-linear parameters have been reported in this study.

  20. Work function contrast and energy band modulation between amorphous and crystalline Ge{sub 2}Sb{sub 2}Te{sub 5} films

    Energy Technology Data Exchange (ETDEWEB)

    Tong, H.; Yang, Z.; Yu, N. N.; Zhou, L. J.; Miao, X. S., E-mail: miaoxs@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-08-24

    The work function (WF) is of crucial importance to dominate the carrier transport properties of the Ge-Sb-Te based interfaces. In this letter, the electrostatic force microscopy is proposed to extract the WF of Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) films with high spatial and energy resolution. The measured WF of as-deposited amorphous GST is 5.34 eV and decreases drastically after the amorphous GST is crystallized by annealing or laser illumination. A 512 × 512 array 2D-WF map is designed to study the WF spatial distribution and shows a good consistency. The WF contrast between a-GST and c-GST is ascribed to band modulation, especially the modification of electron affinity including the contribution of charges or dipoles. Then, the band alignments of GST/n-Si heterostructures are obtained based on the Anderson's rule. Due to the band modulation, the I-V characteristics of a-GST/Si heterojunction and c-GST/Si heterojunction are very different from each other. The quantitative relationship is calculated by solving the Poisson's equation, which agrees well with the I-V measurements. Our findings not only suggest a way to further understand the electrical transport properties of Ge-Sb-Te based interfaces but also provide a non-touch method to distinguish crystalline area from amorphous matrix with high spatial resolution.

  1. A study on the properties of C-doped Ge8Sb2Te11 thin films during an amorphous-to-crystalline phase transition

    Science.gov (United States)

    Park, Cheol-Jin; Kong, Heon; Lee, Hyun-Yong; Yeo, Jong-Bin

    2016-04-01

    In this work, we evaluated the structural, electrical and optical properties of carbon-doped Ge8Sb2Te11 thin films. In a previous work, GeSbTe alloys were doped with different materials in an attempt to improve the thermal stability. Ge8Sb2Te11 and carbon-doped Ge8Sb2Te11 films of 250 nm in thickness were deposited on p-type Si (100) and glass substrates by using a RF magnetron reactive co-sputtering system at room temperature. The fabricated films were annealed in a furnance in the 0 ~ 400°C temperature range. The structural properties were analyzed by using X-ray diffraction (XRD), and the result showed that the carbon-doped Ge8Sb2Te11 had a face-centeredcubic (fcc) crystalline structure and an increased crystallization temperature ( T c ). An increase in the T c leads to thermal stability in the amorphous state. The optical properties were analyzed by using an UV-Vis-IR spectrophotometer, and the result showed an increase in the optical-energy band gap ( E op ) in the crystalline materials and an increase in the E op difference (Δ E op ), which is a good effect for reducing the noise in the memory device. The electrical properties were analyzed by using a 4-point probe, which showed an increase in the sheet resistance ( R s ) in the amorphous state and the crystalline state, which means a reduced programming current in the memory device.

  2. Linear and non-linear optical properties of amorphous Se and M5Se95 (M $=$ Ge, Ga and Zn) films

    Indian Academy of Sciences (India)

    GH ABBADY; K A ALY; Y SADDEEK; N AFIFIY

    2016-12-01

    The variations in structure and optical properties of amorphous a-Se and a-M$_5$Se$_{95}$ (M = Ge, Ga and Zn) films have been studied based on FTIR and optical measurements. FTIR transmittance spectra for a-Se and a-M$_5$Se$_{95}$ (M $=$ Ge, Ga and Zn) glasses were measured as a function of wavenumber. The addition of Ge, Ga and Zn increases the vibrational frequency of the a-Se main band. The absorption edge of Ge$_5$Se$_{95}$ shifted towards long side of the wavelength in comparison with that of a-Se film. This shift increases gradually in the case of Ga$_5$Se$_{95}$ and Zn$_5$Se$_95$ films. So, the optical bandgap ofM5Se95 films was decreased, but the index of refraction was increased. The first and third order of electric susceptibility ($\\chi_{(1)}$ and $\\chi_{(3)}$) and non-linear index of refraction ($n_2$) were increased by adding Ge, Ga and Zn into a-Se.

  3. Coherent phonon modes of crystalline and amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} thin films: A fingerprint of structure and bonding

    Energy Technology Data Exchange (ETDEWEB)

    Shalini, A.; Liu, Y.; Srivastava, G. P.; Hicken, R. J. [Department of Physics and Astronomy, University of Exeter, Exeter EX4 4QL (United Kingdom); Katmis, F.; Braun, W. [Paul Drude Institute for Solid State Electronics, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2015-01-14

    Femtosecond optical pump-probe measurements have been made upon epitaxial, polycrystalline, and amorphous thin films of Ge{sub 2}Sb{sub 2}Te{sub 5} (GST). A dominant coherent optical phonon mode of 3.4 THz frequency is observed in time-resolved anisotropic reflectance (AR) measurements of epitaxial films, and is inferred to have 3-dimensional T{sub 2}-like character based upon the dependence of its amplitude and phase on pump and probe polarization. In contrast, the polycrystalline and amorphous phases exhibit a comparatively weak mode of about 4.5 THz frequency in both reflectivity (R) and AR measurements. Raman microscope measurements confirm the presence of the modes observed in pump-probe measurements, and reveal additional modes. While the Raman spectra are qualitatively similar for all three phases of GST, the mode frequencies are found to be different within experimental error, ranging from 3.2 to 3.6 THz and 4.3 to 4.7 THz, indicating that the detailed crystallographic structure has a significant effect upon the phonon frequency. While the lower frequency (3.6 THz) mode of amorphous GST is most likely associated with GeTe{sub 4} tetrahedra, modes in epitaxial (3.4 THz) and polycrystalline (3.2 THz) GST could be associated with either GeTe{sub 6} octahedra or Sb-Te bonds within defective octahedra. The more polarizable Sb-Te bonds are the most likely origin of the higher frequency (4.3–4.7 THz) mode, although the influence of Te-Te bonds cannot be excluded. The effect of high pump fluence, which leads to irreversible structural changes, has been explored. New modes with frequency of 3.5/3.6 THz in polycrystalline/amorphous GST may be associated with Sb{sub 2}Te{sub 3} or GeTe{sub 4} tetrahedra, while a 4.2 THz mode observed in epitaxial GST may be related to segregation of Sb.

  4. Pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} on amorphous dielectric layers towards monolithic 3D photonic integration

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haofeng; Brouillet, Jeremy; Wang, Xiaoxin; Liu, Jifeng, E-mail: Jifeng.Liu@dartmouth.edu [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States)

    2014-11-17

    We demonstrate pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} crystallized on amorphous layers at <450 °C towards 3D Si photonic integration. We developed two approaches to seed the lateral single crystal growth: (1) utilize the Gibbs-Thomson eutectic temperature depression at the tip of an amorphous GeSn nanotaper for selective nucleation; (2) laser-induced nucleation at one end of a GeSn strip. Either way, the crystallized Ge{sub 0.89}Sn{sub 0.11} is dominated by a single grain >18 μm long that forms optoelectronically benign twin boundaries with others grains. These pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} patterns are suitable for monolithic 3D integration of active photonic devices on Si.

  5. High Power SiGe X-Band (8~10GHz) Heterojunction Bipolar Transistors and Amplifiers

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Limited by increased parasitics and thermal effects as device size increases, current commercial SiGe power HBTs are difficult to operate at X-band (8~ 12GHz) frequencies with adequate power added efficiencies at high power levels. We find that, by changing the heterostructure and doping profile of SiGe HBTs, their power gain can be significantly improved without resorting to substantial lateral scaling. Furthermore, employing a common-base configuration with a proper doping profile instead of a common-emitter configuration improves the power gain characteristics of SiGe HBTs, thus permitting these devices to be efficiently operated at X-band frequencies. In this paper,we report the results of SiGe power HBTs and MMIC power amplifiers operating at 8~10GHz. At 10GHz,a 22.5dBm (178mW) RF output power with a concurrent gain of 7.32dB is measured at the peak power-added efficiency of 20.0%, and a maximum RF output power of 24.0dBm (250mW) is achieved from a 20 emitter finger SiGe power HBT. The demonstration of a single-stage X-band medium-power linear MMIC power amplifier is also realized at 8GHz. Employing a 10-emitter finger SiGe HBT and on-chip input and output matching passive components, a linear gain of 9.7dB,a maximum output power of 23.4dBm,and peak power added efficiency of 16% are achieved from the power amplifier. The MMIC exhibits very low distortion with 3rd order intermodulation (IM) suppression C/I of -13dBc at an output power of 21.2dBm and over 20dBm 3rd order output intercept point (OIP3).

  6. Textured Sb2Te3 films and GeTe/Sb2Te3 superlattices grown on amorphous substrates by molecular beam epitaxy

    Science.gov (United States)

    Boschker, Jos E.; Tisbi, E.; Placidi, E.; Momand, Jamo; Redaelli, Andrea; Kooi, Bart J.; Arciprete, Fabrizio; Calarco, Raffaella

    2017-01-01

    The realization of textured films of 2-dimensionally (2D) bonded materials on amorphous substrates is important for the integration of this material class with silicon based technology. Here, we demonstrate the successful growth by molecular beam epitaxy of textured Sb2Te3 films and GeTe/Sb2Te3 superlattices on two types of amorphous substrates: carbon and SiO2. X-ray diffraction measurements reveal that the out-of-plane alignment of grains in the layers has a mosaic spread with a full width half maximum of 2.8°. We show that a good texture on SiO2 is only obtained for an appropriate surface preparation, which can be performed by ex situ exposure to Ar+ ions or by in situ exposure to an electron beam. X-ray photoelectron spectroscopy reveals that this surface preparation procedure results in reduced oxygen content. Finally, it is observed that film delamination can occur when a capping layer is deposited on top of a superlattice with a good texture. This is attributed to the stress in the capping layer and can be prevented by using optimized deposition conditions of the capping layer. The obtained results are also relevant to the growth of other 2D materials on amorphous substrates.

  7. Textured Sb2Te3 films and GeTe/Sb2Te3 superlattices grown on amorphous substrates by molecular beam epitaxy

    Directory of Open Access Journals (Sweden)

    Jos E. Boschker

    2017-01-01

    Full Text Available The realization of textured films of 2-dimensionally (2D bonded materials on amorphous substrates is important for the integration of this material class with silicon based technology. Here, we demonstrate the successful growth by molecular beam epitaxy of textured Sb2Te3 films and GeTe/Sb2Te3 superlattices on two types of amorphous substrates: carbon and SiO2. X-ray diffraction measurements reveal that the out-of-plane alignment of grains in the layers has a mosaic spread with a full width half maximum of 2.8°. We show that a good texture on SiO2 is only obtained for an appropriate surface preparation, which can be performed by ex situ exposure to Ar+ ions or by in situ exposure to an electron beam. X-ray photoelectron spectroscopy reveals that this surface preparation procedure results in reduced oxygen content. Finally, it is observed that film delamination can occur when a capping layer is deposited on top of a superlattice with a good texture. This is attributed to the stress in the capping layer and can be prevented by using optimized deposition conditions of the capping layer. The obtained results are also relevant to the growth of other 2D materials on amorphous substrates.

  8. Distribution of Local Open-Circuit Voltage on Amorphous and Nanocrystalline Mixed-Phase Si:H and SiGe:H Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C.-S.; Moutinho, H. R.; Al-Jassim, M. M.; Kazmerski, L. L.; Yan, B.; Owens, J. M.; Yang, J.; Guha, S.

    2006-05-01

    Local open-circuit voltage (Voc) distributions on amorphous and nanocrystalline mixed-phase silicon solar cells were measured using a scanning Kelvin probe microscope (SKPM) on the p layer of an n-i-p structure without the top ITO contact. During the measurement, the sample was illuminated with a laser beam that was used for the atomic force microscopy (AFM). Therefore, the surface potential measured by SKPM is the sum of the local Voc and the difference in workfunction between the p layer and the AFM tip. Comparing the SKPM and AFM images, we find that nanocrystallites aggregate in the amorphous matrix with an aggregation size of {approx}0.5 ..mu..m in diameter, where many nanometer-size grains are clustered. The Voc distribution shows valleys in the nanocrystalline aggregation area. The transition from low to high Voc regions is a gradual change within a distance of about 1 ..mu..m. The minimum Voc value in the nanocrystalline clusters in the mixed-phase region is larger than the Voc of a nc-Si:H single-phase solar cell. These results could be due to lateral photo-charge redistribution between the two phases. We have also carried out local Voc measurements on mixed-phase SiGe:H alloy solar cells. The magnitudes of Voc in the amorphous and nanocrystalline regions are consistent with the J-V measurements.

  9. Effect of Cd and Pb impurities on the optical properties of fresh evaporated amorphous (As2Se3)90Ge10 thin films

    Science.gov (United States)

    Sharma, P.; Katyal, S. C.

    2009-05-01

    Transmission spectra (400-1500 nm) of thermally evaporated amorphous [(As2Se3)90Ge10]95M5 thin films have been analyzed to study the effect of impurities (M = Cd and Pb) on their optical properties. The refractive index increases with addition of metal impurities. The dispersion of refractive index has been studied using Wemple-DiDomenico single oscillator model. The optical gap has been estimated using Tauc’s extrapolation and was found to decrease with the addition of metal impurities from 1.46 to 1.36 eV (Cd) and 1.41 eV (Pb) with an uncertainty of ±0.01 eV. The change in optical properties with metal impurities has been explained on the basis of density, polarizability and bond energy of the system.

  10. Superconducting nanowire single photon detectors fabricated from an amorphous Mo{sub 0.75}Ge{sub 0.25} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Verma, V. B.; Lita, A. E.; Vissers, M. R.; Marsili, F.; Pappas, D. P.; Mirin, R. P.; Nam, S. W. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States)

    2014-07-14

    We present the characteristics of superconducting nanowire single photon detectors (SNSPDs) fabricated from amorphous Mo{sub 0.75}Ge{sub 0.25} thin-films. Fabricated devices show a saturation of the internal detection efficiency at temperatures below 1 K, with system dark count rates below 500 cps. Operation in a closed-cycle cryocooler at 2.5 K is possible with system detection efficiencies exceeding 20% for SNSPDs which have not been optimized for high detection efficiency. Jitter is observed to vary between 69 ps at 250 mK and 187 ps at 2.5 K using room temperature amplifiers.

  11. Structural investigation of the amorphous/crystalline interface by means of quantitative high-resolution transmission electron microscopy on the systems a-Si/c-Si and a-Ge/c-Si; Strukturelle Untersuchung der amorph/kristallinen Grenzflaeche mittels quantitativer hochaufloesender Transmissionselektronenmikroskopie an den Systemen a-Si/c-Si und a-Ge/c-Si

    Energy Technology Data Exchange (ETDEWEB)

    Thiel, K.

    2006-11-02

    In this Thesis the interfaces between covalently bonded crystalline and amorphous materials were studied with regard to the induced ordering in the amorphous material in the interfacial region by means of high-resolution transmission electron microscopy (HREM). The interface between amorphous germanium and crystalline silicon and the interface between amorphous and crystalline silicon served as material system. In order to quantify the influence of the crystalline order on the amorphous material, the HREM images were periodically averaged along the interface. The intensity components, which are correlated with the period of the lattice image, could thus be separated from the statistical intensity fluctuations, which are characteristic for images of amorphous materials. Since amorphous materials can only be described meaningful by statistical distribution functions, for the induced order a three-dimensional distribution function {rho}{sub 3D}(r) was taken as a basis, which describes the probability to find an atom in the amorphous material, if r=0 is the position of an atom in the crystal. Its two-dimensional projection, {rho}, can be determined using iterative image matching techniques on averaged experimental and simulated interface images. For the analyzed material systems {rho} exhibits lateral ordering as well as a pronounced layering in the vicinity of the interface. In the case of the a-Si/c-Si sample the mean orientation of bonds was 70.5 , as is in the case of the undistorted diamond lattice, while for the a-Ge/c-Si sample 65 resulted. The standard deviation for the distribution of the deviations from the mean bond angle yields for the a-Ge/c-Si sample in the first atomic layer a value of 11.3 and for the a-Si/c-Si sample 1.9 . These results suggest the conclusion, that the differences in these values are to be interpreted as the reaction of the amorphous material to the volume misfit. Although for both material systems 1.4 nm was calculated for the width

  12. Distribution of Local Open-Circuit Voltage on Amorphous and Nanocrystalline Mixed-Phase Si:H and SiGe:H Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C.-S.; Moutinho, H. R.; Al-Jassim, M. M.; Kazmerski, L. L.; Yan, B.; Owens, J. M.; Yang, J.; Guha, S.

    2006-01-01

    Local open-circuit voltage (V{sub oc}) distributions on amorphous and nanocrystalline mixed-phase silicon solar cells were measured using a scanning Kelvin probe microscope (SKPM) on the p layer of an n-i-p structure without the top ITO contact. During the measurement, the sample was illuminated with a laser beam that was used for the atomic force microscopy (AFM). Therefore, the surface potential measured by SKPM is the sum of the local V{sub oc} and the difference in workfunction between the p layer and the AFM tip. Comparing the SKPM and AFM images, we find that nanocrystallites aggregate in the amorphous matrix with an aggregation size of {approx}0.5 {micro}m in diameter, where many nanometer-size grains are clustered. The V{sub oc} distribution shows valleys in the nanocrystalline aggregation area. The transition from low to high V{sub oc} regions is a gradual change within a distance of about 1 {micro}m. The minimum V{sub oc} value in the nanocrystalline clusters in the mixed-phase region is larger than the V{sub oc} of a nc-Si:H single-phase solar cell. These results could be due to lateral photo-charge redistribution between the two phases. We have also carried out local V{sub oc} measurements on mixed-phase SiGe:H alloy solar cells. The magnitudes of V{sub oc} in the amorphous and nanocrystalline regions are consistent with the J-V measurements.

  13. Power SiGe Heterojunction Bipolar Transistors (HBTs) Fabricated by Fully Self-Aligned Double Mesa Technology

    Science.gov (United States)

    Lu, Liang-Hung; Mohammadi, Saeed; Ma, Zhen-Qiang; Ponchak, George E.; Alterovitz, Samuel A.; Strohm, Karl M.; Luy, Johann-Friedrich; Downey, Alan (Technical Monitor)

    2001-01-01

    Multifinger SiGe HBTs have been fabricated using a novel fully self-aligned double-mesa technology. With the novel process technology, a common-emitter 2x2x30 sq micrometer device exhibits high maximum oscillating frequency (f(sub max)) and cut-off frequency (f(sub T)) of 78 and 37 GHz, respectively. In class-A operation, a multifinger device with l0x2x30 sq micrometer emitter is expected to provide an output power of 25.6 dBm with a gain of 10 dB and a maximum power added efficiency (PAE) of 30.33% at 8 GHz.

  14. ac conductivity and dielectric properties of amorphous Se{sub 80}Te{sub 20-x}Ge{sub x} chalcogenide glass film compositions

    Energy Technology Data Exchange (ETDEWEB)

    Hegab, N.A. [Physics Department, Faculty of Education, Ain Shams University, Cairo (Egypt)], E-mail: abir_net_2005@hotmail.com; Afifi, M.A.; Atyia, H.E.; Farid, A.S. [Physics Department, Faculty of Education, Ain Shams University, Cairo (Egypt)

    2009-05-27

    Thin films of the prepared Se{sub 80}Te{sub 20-x}Ge{sub x} (x = 5, 7 and 10 at.%) were prepared by thermal evaporation technique. X-ray diffraction patterns showed that the films were in amorphous state. The ac conductivity and dielectric properties of the investigated film compositions were studied in the frequency range 0.1-100 kHz and in temperature range (303-373 K). The experimental results indicated that the ac conductivity and the dielectric properties depended on the temperature and frequency. The ac conductivity is found to obey the {omega}{sup s} law, in accordance with the hopping model, s is found to be temperature dependent (s < 1) and its value goes down as the temperature is increased. The temperature dependence of ac conductivity can be reasonably interpreted in terms of the correlated barrier hopping (CBH) model. Values of dielectric constant {epsilon}{sub 1} and dielectric loss {epsilon}{sub 2} were found to decrease with frequency and increase with temperature. The maximum barrier height W{sub m}, calculated from dielectric measurements according to Guintini equation, agrees with that proposed by the theory of hopping over potential barrier as suggested by Elliott in case of chalcogenide glasses. The density of localized states was estimated for the studied film compositions. The variation of the studied properties with Ge content was also investigated.

  15. Far-Infrared and Raman Spectroscopy Investigation of Phonon Modes in Amorphous and Crystalline Epitaxial GeTe-Sb2Te3 Alloys

    Science.gov (United States)

    Bragaglia, V.; Holldack, K.; Boschker, J. E.; Arciprete, F.; Zallo, E.; Flissikowski, T.; Calarco, R.

    2016-06-01

    A combination of far-infrared and Raman spectroscopy is employed to investigate vibrational modes and the carrier behavior in amorphous and crystalline ordered GeTe-Sb2Te3 alloys (GST) epitaxially grown on Si(111). The infrared active GST mode is not observed in the Raman spectra and vice versa, indication of the fact that inversion symmetry is preserved in the metastable cubic phase in accordance with the Fm3 space group. For the trigonal phase, instead, a partial symmetry break due to Ge/Sb mixed anion layers is observed. By studying the crystallization process upon annealing with both the techniques, we identify temperature regions corresponding to the occurrence of different phases as well as the transition from one phase to the next. Activation energies of 0.43 eV and 0.08 eV for the electron conduction are obtained for both cubic and trigonal phases, respectively. In addition a metal-insulator transition is clearly identified to occur at the onset of the transition between the disordered and the ordered cubic phase.

  16. Ge20Sb15Se65薄膜的热致光学特性变化研究*%Thermal-induced optical changes in the amorphous Ge20Sb15Se65 film∗

    Institute of Scientific and Technical Information of China (English)

    宗双飞; 沈祥; 徐铁峰; 陈昱; 王国祥; 陈芬; 李军; 林常规; 聂秋华

    2013-01-01

    The amorphous Ge20Sb15Se65 thin film was prepared by magnetron sputtering deposition technique. Effect of heat treatment temperature in the range of 150—400◦C on the optical properties of Ge20Sb15Se65 thin films has been investigated. The microstructure and optical properties of the films were characterized by UV-Vis, Raman spectroscopy and XRD, the optical constant was calculated using the Swanepoel method and Tauc’s law from the optical transmission spectra. Results indicate that when the annealing temperature (Ta) is lower than the glass transition temperature (Tg), the optical band gap (Eoptg ) increases from 1.845 to 1.932 eV, and the refractive index decreases from 2.61 to 2.54, while the optical band gap decreases from 1.932 to 1.822 eV and the refractive index increases from 2.54 to 2.71 with a further increase of Ta. The results were explained in terms of the Mott and Davis model for amorphous materials and amorphous to crystalline structural transformations. It is well consistent with the results of structure analysis by XRD and Raman spectroscopy.%  采用磁控溅射法制备了Ge20Sb15Se65薄膜,研究热处理温度(150-400◦C)对薄膜光学特性的影响.通过分光光度计、X射线衍射仪、显微拉曼光谱仪对热处理前后薄膜样品的光学特性和微观结构进行了表征,并根据Swanepoel方法以及Tauc公式分别计算了薄膜折射率色散曲线和光学带隙等参数.结果表明当退火温度(Ta)小于薄膜的玻璃转化温度(Tg)时,薄膜的光学带隙(Eoptg )随着退火温度的增加由1.845 eV上升至1.932 eV,而折射率由2.61降至2.54;当退火温度大于薄膜的玻璃转化温度时,薄膜的光学带隙随退火温度的增加由1.932 eV降至1.822 eV,折射率则由2.54增至2.71.最后利用Mott和Davis提出的非晶材料由非晶到晶态的结构转变模型对结果进行了解释,并通过薄膜XRD和Raman光谱进一步验证了结构变化是薄膜热致变化的重要原因.

  17. Compositional Dependence of the Optical Properties of Amorphous Semiconducting Glass Se80Ge20- x Cd x (0 ≤ x ≤ 12 at.%) Thin Films

    Science.gov (United States)

    Hegab, N. A.; Farid, A. S.; Shakra, A. M.; Afifi, M. A.; Alrebati, A. M.

    2016-07-01

    Se80Ge20- x Cd x (0 ≤ x ≤ 12 at.%) compositions were prepared by a quenching technique. Thin films of the obtained compositions were deposited on dry clean glass substrates by a thermal evaporation technique. The chemical composition of the film samples have been determined by energy dispersive x-ray spectroscopy (EDX). X-ray diffraction measurements showed the amorphous nature of the studied films. The optical constants ( n, k) were determined for the studied films using spectrophotometric measurements of transmittance T( λ) in the wavelength range (350 nm to 2500 nm), and using Swanepoel's method. The values of the dispersion energy E d, oscillator energy E o, the lattice dielectric constant ɛ ∞L and the high-frequency dielectric constant ɛ s were determined. The optical band gap Eg^{{opt}} is estimated for all compositions from the absorption coefficient α. The analysis of the optical absorption data revealed the existence of allowed indirect transitions for all compositions. The effect of adding Cd content on the obtained optical parameters was also discussed.

  18. Bipolar Disorder

    Science.gov (United States)

    Bipolar disorder is a serious mental illness. People who have it go through unusual mood changes. They go ... The down feeling is depression. The causes of bipolar disorder aren't always clear. It runs in families. ...

  19. Bipolar Disorder (For Teens)

    Science.gov (United States)

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Bipolar Disorder KidsHealth > For Teens > Bipolar Disorder A A ... Bipolar Disorder en español Trastorno bipolar What Is Bipolar Disorder? Bipolar disorders are one of several medical ...

  20. Optimization, analysis, and fabrication of silicon-germanium heterojunction bipolar transistors

    Science.gov (United States)

    Kwok, Kai Hay

    This thesis deals with the optimization, analysis, and fabrication of silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs). Two vertical base profile optimization studies for improving the high-frequency performance of SiGe HBTs are presented. In the first study, the Ge profile is optimized for the minimum contribution of the emitter and base delay times to the transition frequency in the low-injection regime. A fixed Ge dose is used as the optimization constraint. Non-quasi-static effects at high frequencies are taken into account. It is shown that the graded Ge profile is more effective than the box Ge profile in minimizing the two delay time contributors for SiGe HBTs with today's typical emitter and base dimensions. In the second optimization study, the base doping and Ge profiles are optimized for minimum base delay time in low- and high-injection regimes before the onset of Kirk effect. Fixed Ge dose, intrinsic base resistance, and base concentration near the emitter are adopted as optimization constraints. The effect of plasma-induced bandgap narrowing in high injection is considered. An iteration scheme for calculating the base delay time for a wide range of collector current densities is developed. It is shown that the retrograde base doping profile with graded Ge profiles gives the minimum base delay time in both low- and high-injection regimes. An analysis of the retrograde portion of a base retrograde doping profile in a SiGe HBT is also performed. A closed-form analytical expression of the base delay time is derived with various physical effects taken into consideration. The relative importance of the physical effects is assessed. It is found that the adverse effect of the retrograde portion of the base retrograde doping profile on the base delay time is less pronounced than expected, especially when a high Ge grading exists across the base. It is also shown that the effect of the field dependency of the electron diffusivity needs to be

  1. Highly effective strain-induced band-engineering of (111) oriented, direct-gap GeSn crystallized on amorphous SiO2 layers

    Science.gov (United States)

    Li, Haofeng; Wang, Xiaoxin; Liu, Jifeng

    2016-03-01

    We demonstrate highly effective strain-induced band-engineering of (111) oriented direct-gap Ge1-xSnx thin films (0.074 GeSn films also demonstrate high thermal stability, offering both excellent direct-gap optoelectronic properties and fabrication/operation robustness for integrated photonics.

  2. Structure of amorphous GeSe9 by neutron diffraction and first-principles molecular dynamics: Impact of trajectory sampling and size effects

    Science.gov (United States)

    Le Roux, Sébastien; Bouzid, Assil; Kim, Kye Yeop; Han, Seungwu; Zeidler, Anita; Salmon, Philip S.; Massobrio, Carlo

    2016-08-01

    The structure of glassy GeSe9 was investigated by combining neutron diffraction with density-functional-theory-based first-principles molecular dynamics. In the simulations, three different models of N = 260 atoms were prepared by sampling three independent temporal trajectories, and the glass structures were found to be substantially different from those obtained for models in which smaller numbers of atoms or more rapid quench rates were employed. In particular, the overall network structure is based on Sen chains that are cross-linked by Ge(Se4)1/2 tetrahedra, where the latter are predominantly corner as opposed to edge sharing. The occurrence of a substantial proportion of Ge-Se-Se connections does not support a model in which the material is phase separated into Se-rich and GeSe2-rich domains. The appearance of a first-sharp diffraction peak in the Bhatia-Thornton concentration-concentration partial structure factor does, however, indicate a non-uniform distribution of the Ge-centered structural motifs on an intermediate length scale.

  3. Distribution of Local Open-Circuit Voltage on Amorphous and Nanocrystalline Mixed-Phase Si:H and SiGe:H Solar Cells (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C.-S.; Moutinho, H. R.; Al-Jassim, M. M.; Kazmerski, L. L.; Yan, B.; Yang, J.; Guha, S.

    2006-05-01

    By combining SKPM and AFM, they have developed a method to measure the local V{sub oc} distribution in mixed-phase solar cells. The results clearly show the nanocrystalline aggregation. The V{sub oc} is smaller in the nanocrystalline aggregates than in the surrounding amorphous matrix, and the transition from the low to high V{sub oc} is a gradual change. Although there are some lateral charge redistributions, a clear distinction between the amorphous and nanocrystalline regions has been observed. The current SKPM results and previous C-AFM results provide extra support for the two-diode model for explaining the carrier transport in the mixed-phase solar cells.

  4. An optical study of amorphous (Se{sub 80}Te{sub 20}){sub 100-x}Ge{sub x} thin films using their transmission spectra

    Energy Technology Data Exchange (ETDEWEB)

    Mainika; Thakur, Nagesh [Department of Physics, H P University, Summer Hill Shimla, HP-171005 (India); Sharma, Pankaj; Katyal, S C [Department of Physics, Jaypee University of Information Technology, Waknaghat-173215 (India)], E-mail: mainika_phy@rediffmail.com, E-mail: pankaj.sharma@juit.ac.in

    2008-12-07

    Optical constants (refractive index and extinction coefficient) have been studied for a-(Se{sub 80}Te{sub 20}){sub 100-x}Ge{sub x} (x = 0, 2, 4, 6) thin films using transmission spectra in the wavelength range 500-2500 nm. It is observed from optical transmission measurements that the optical energy gap (E{sub g}) increases while the refractive index (n) and the extinction coefficient (k) decrease with the incorporation of Ge in the Se-Te system. The increase in the optical energy gap is interpreted by correlating the optical energy gap with the decrease in electronegativity and increase in the heat of atomization (H{sub s}). The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple-DiDomenico model.

  5. Far-infrared study of amorphous Ge{sub 0.17}Se{sub 0.83-x}Sb{sub x} chalcogenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Parikshit [Department of Physics, H.P. University, Summer Hill, Shimla 171005 (India)], E-mail: sharma_parikshit@yahoo.com; Rangra, V.S. [Department of Physics, H.P. University, Summer Hill, Shimla 171005 (India); Sharma, Pankaj [Department of Physics, Jaypee University of Information Technology, Waknaghat, Solan, H.P. 173215 (India)], E-mail: pankaj.sharma@juit.ac.in; Katyal, S.C. [Department of Physics, Jaypee University of Information Technology, Waknaghat, Solan, H.P. 173215 (India)

    2009-07-08

    Far-infrared transmission spectra of Ge{sub 0.17}Se{sub 0.83-x}Sb{sub x} (x = 0, 0.03, 0.09, 0.12, 0.15) glassy alloys are obtained in the spectral range 500-200 cm{sup -1} at room temperature. The results are interpreted in terms of the vibrations of the isolated molecular units, in such a way as to preserve fourfold and twofold coordination for Ge and Se atoms, respectively. In the Ge{sub 0.17}Se{sub 0.83} bulk glass the main absorption bands appear at {approx}250 cm{sup -1} and 300 cm{sup -1}. With the increase in Sb content some new bands start appearing at 228-231 cm{sup -1} and 250-260 cm{sup -1}. Theoretical calculations (bond energy, relative probability density of bond formation, force constant and wave number) were also made to justify the results.

  6. Metastable Ge nanocrystalline in SiGe matrix for photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Yao-Tsung; Su, Chien-Hao [Department of Chemical and Materials Engineering, National Central University, Taoyuan City 320, Taiwan (China); Chang, Jenq-Yang [Department of Optics and Photonics, National Central University, Taoyuan City 320, Taiwan (China); Cheng, Shao-Liang; Lin, Po-Chen [Department of Chemical and Materials Engineering, National Central University, Taoyuan City 320, Taiwan (China); Wu, Albert T., E-mail: atwu@ncu.edu.tw [Department of Chemical and Materials Engineering, National Central University, Taoyuan City 320, Taiwan (China)

    2015-09-15

    Highlights: • Amorphous Si{sub 1−x}Ge{sub x} films were prepared by co-sputtering by using rapid thermal annealing to form nanocrystal films. • Si–Ge alloy does not form total solid solution that is shown in phase diagram. • HRTEM images indicated that Ge atoms segregated and formed Ge clusters that are embedded in the amorphous Si–Ge matrix. • Ge segregation permitted high mobility; the grain size increased and the resistivity decreased with higher Ge content. • The rectifying property became stronger with the Ge fraction in the Si{sub 1−x}Ge{sub x} diodes. Si{sub 1−x}Ge{sub x} diodes are used as photodetectors, which provide a greater output current under illumination. - Abstract: Amorphous Si{sub 1−x}Ge{sub x} films were prepared by co-sputtering on an oxidized Si wafer, followed by rapid thermal annealing to form nanocrystal films. The formation of Ge nanocrystals was not at thermodynamic equilibrium formed in the amorphous Si{sub 1−x}Ge{sub x} matrix. High-resolution transmission electron microscopy was used to characterize the increase in the size of the grains in the Ge nanocrystals as the Ge content increased. The Ge nanocrystals have a greater absorption in the near-infrared region and higher carrier mobility than SiGe crystals, and the variation in their grain sizes can be used to tune the bandgap. This characteristic was exploited herein to fabricate n-Si{sub 1−x}Ge{sub x}/p-Si{sub 1−x}Ge{sub x} p–n diodes on insulating substrates, which were then examined by analyzing their current–voltage characteristics. The rectifying property became stronger as the fraction of Ge in the Si{sub 1−x}Ge{sub x} films increased. The Si{sub 1−x}Ge{sub x} diodes are utilized as photodetectors that have a large output current under illumination. This paper elucidates the correlations between the structural, optical and electrical properties and the p–n junction performance of the film.

  7. Neutrality in bipolar structures

    DEFF Research Database (Denmark)

    Montero, Javier; Rodríguez, J. Tinguaro; Franco, Camilo

    2014-01-01

    In this paper, we want to stress that bipolar knowledge representation naturally allows a family of middle states which define as a consequence different kinds of bipolar structures. These bipolar structures are deeply related to the three types of bipolarity introduced by Dubois and Prade, but our...... approach offers a systematic explanation of how such bipolar structures appear and can be identified....

  8. Influence of temperature and frequency on the AC conductivity and dielectric properties for Ge{sub 15}Se{sub 60}Bi{sub 25} amorphous films

    Energy Technology Data Exchange (ETDEWEB)

    Atyia, H.E., E-mail: hebaelghrip@hotmail.com; Hegab, N.A.; Affi, M.A.; Ismail, M.I.

    2013-10-15

    Highlights: •σ{sub ac}(ω) obeyed the Aω{sup s} law, s is the frequency exponent decreases with increasing temperature. •σ{sub ac}(ω) increases with increasing temperature, with two slopes which suggests two different regimes σ{sub f}, σ{sub s.} •The dielectric constant ε{sub 1} and dielectric loss ε{sub 2} increase with temperature and decrease with frequency. •Value of the maximum barrierheight W{sub m} is in good agreement with the theory of hopping. -- Abstract: Thin films of Ge{sub 15}Se{sub 60}Bi{sub 25} are prepared by thermal evaporation technique on to well cleaned glass substrates. The film thicknesses are measured by quartz crystal monitor method. Thin film capacitors of the type (Al–Ge{sub 15}Se{sub 60}Bi{sub 25}–Al) have been fabricated. The films were well characterized by X-ray diffraction, differential thermal analysis and energy dispersive X-ray spectroscopy. AC conduction and dielectric studies performed on a stabilized samples of thickness range (89.3–214.3 nm) at various frequencies (10{sup 2}–10{sup 5} Hz) and temperatures (303–413 K). From the AC conduction studies, it is confirmed that the mechanism responsible for the conduction process is hopping. The variations of the dielectric constant and loss as function of frequency and temperature are observed and the results are discussed. Finally, the maximum barrier height W{sub m} and the density of states N(E{sub F}) were determined.

  9. Transtorno bipolar

    Directory of Open Access Journals (Sweden)

    Alda Martin

    1999-01-01

    Full Text Available Os resultados de estudos de famílias sugerem que o transtorno bipolar tenha uma base genética. Essa hipótese foi reforçada em estudos de adoção e de gêmeos. A herança do transtorno bipolar é complexa, envolve vários genes, além de apresentar heterogeneidade e interação entre fatores genéticos e não-genéticos. Achados, que já foram replicados, já implicaram os cromossomos 4, 12, 18 e 21, entre outros, na busca por genes de suscetibilidade. Os resultados mais promissores foram obtidos através de estudos de ligação. Por outro lado, os estudos de associação geraram dados interessantes, mas ainda vagos. Os estudos de populações de pacientes homogêneos e a melhor definição do fenótipo deverão contribuir para avanços futuros. A identificação dos genes relacionados ao transtorno bipolar irá permitir o melhor entendimento e tratamento dessa doença.

  10. Amorphous nanophotonics

    CERN Document Server

    Scharf, Toralf

    2013-01-01

    This book represents the first comprehensive overview over amorphous nano-optical and nano-photonic systems. Nanophotonics is a burgeoning branch of optics that enables many applications by steering the mould of light on length scales smaller than the wavelength with devoted nanostructures. Amorphous nanophotonics exploits self-organization mechanisms based on bottom-up approaches to fabricate nanooptical systems. The resulting structures presented in the book are characterized by a deterministic unit cell with tailored geometries; but their spatial arrangement is not controlled. Instead of periodic, the structures appear either amorphous or random. The aim of this book is to discuss all aspects related to observable effects in amorphous nanophotonic material and aspects related to their design, fabrication, characterization and integration into applications. The book has an interdisciplinary nature with contributions from scientists in physics, chemistry and materials sciences and sheds light on the topic fr...

  11. On the crystallization of amorphous germanium films

    Science.gov (United States)

    Edelman, F.; Komem, Y.; Bendayan, M.; Beserman, R.

    1993-06-01

    The incubation time for crystallization of amorphous Ge (a-Ge) films, deposited by e-gun, was studied as a function of temperature between 150 and 500°C by means of both in situ transmission electron microscopy and Raman scattering spectroscopy. The temperature dependence of t0 follows an Arrhenius curve with an activation energy of 2.0 eV for free-sustained a-Ge films. In the case where the a-Ge films were on Si 3N 4 substrate, the activation energy of the incubation process was 1.3 eV.

  12. Bipolar Disorder (For Teens)

    Science.gov (United States)

    ... disorder, but they think that biochemical, genetic, and environmental_factors may all be involved. It's believed this condition ... the gene or genes involved in bipolar disorder. Environmental factors may play a role in bipolar disorder. For ...

  13. Types of Bipolar Disorder

    Science.gov (United States)

    ... same time, which is also known as major depressive disorder with mixed features. Bipolar Disorder and Other Illnesses Some bipolar disorder symptoms are similar to other illnesses, which can make ...

  14. Cytokines in bipolar disorder

    DEFF Research Database (Denmark)

    Munkholm, Klaus; Vinberg, Maj; Vedel Kessing, Lars

    2012-01-01

    BACKGROUND: Current research and hypothesis regarding the pathophysiology of bipolar disorder suggests the involvement of immune system dysfunction that is possibly related to disease activity. Our objective was to systematically review evidence of cytokine alterations in bipolar disorder according...... to affective state. METHODS: We conducted a systemtic review of studies measuring endogenous cytokine concentrations in patients with bipolar disorder and a meta-analysis, reporting results according to the PRISMA statement. RESULTS: Thirteen studies were included, comprising 556 bipolar disorder patients...

  15. 高速NPN锗硅异质结双极晶体管的设计与制作%Design and Fabrication of High Speed NPN SiGe Heterojunction Bipolar Transistor

    Institute of Scientific and Technical Information of China (English)

    钱文生; 刘冬华; 陈帆; 陈雄斌; 石晶; 段文婷; 胡君; 黄景丰

    2012-01-01

    The paper presents the device structure and fabrication process of 0.18 μm high speed SiGe HBT. The DC and RF characteristics of SiGe HBT are analyzed with typical Ft=U0 GHz, .BVcez = 1- 8 V and β=270. The impact of different process conditions on SiGe HBT performance is investigated, including the doping of implanted collector, EPI SiGeC base and polysili-con emitter as well as the thickness of SiGeC base. The optimum process conditions are exhibited.%报告了0.18 μm高速N型锗硅异质结双极晶体管(SiGe HBT)的器件结构和制作工艺.分析了SiGe HBT器件的直流和射频特性,其截止频率为110 GHz,击穿电压为1.8V,电流增益为270.研究了集电区掺杂及锗硅碳外延基区的厚度与掺杂工艺条件对器件特性的影响,并给出最优化的工艺条件.

  16. Nutrition and Bipolar Depression.

    Science.gov (United States)

    Beyer, John L; Payne, Martha E

    2016-03-01

    As with physical conditions, bipolar disorder is likely to be impacted by diet and nutrition. Patients with bipolar disorder have been noted to have relatively unhealthy diets, which may in part be the reason they also have an elevated risk of metabolic syndrome and obesity. An improvement in the quality of the diet should improve a bipolar patient's overall health risk profile, but it may also improve their psychiatric outcomes. New insights into biological dysfunctions that may be present in bipolar disorder have presented new theoretic frameworks for understanding the relationship between diet and bipolar disorder.

  17. Stress originating from nanovoids in hydrogenated amorphous semiconductors

    Science.gov (United States)

    Wang, Zumin; Flötotto, David; Mittemeijer, Eric J.

    2017-03-01

    Structural inhomogeneities in the form of voids of nanometer sizes (nanovoids) have long been known to be present in hydrogenated amorphous semiconductors (Si, Ge). The physical and electrical properties of hydrogenated amorphous semiconductors can be pronouncedly influenced by the presence and characteristics of such nanovoids. In this work, by measuring in situ the intrinsic stress developments during deposition of pure, amorphous and of hydrogenated amorphous semiconductor (Si, Ge) thin films, under the same conditions in ultrahigh vacuum and on a comparative basis, a major source of tensile stress development could be ascribed to the occurrence of nanovoids in a-Si:H and a-Ge:H. The measurements allowed a quantitative evaluation of the surface stress acting along the surface of the nanovoids: 1.1-1.9 N/m for a-Si:H and 0.9-1.9 N/m for a-Ge:H.

  18. Oxide bipolar electronics: materials, devices and circuits

    Science.gov (United States)

    Grundmann, Marius; Klüpfel, Fabian; Karsthof, Robert; Schlupp, Peter; Schein, Friedrich-Leonhard; Splith, Daniel; Yang, Chang; Bitter, Sofie; von Wenckstern, Holger

    2016-06-01

    We present the history of, and the latest progress in, the field of bipolar oxide thin film devices. As such we consider primarily pn-junctions in which at least one of the materials is a metal oxide semiconductor. A wide range of n-type and p-type oxides has been explored for the formation of such bipolar diodes. Since most oxide semiconductors are unipolar, challenges and opportunities exist with regard to the formation of heterojunction diodes and band lineups. Recently, various approaches have led to devices with high rectification, namely p-type ZnCo2O4 and NiO on n-type ZnO and amorphous zinc-tin-oxide. Subsequent bipolar devices and applications such as photodetectors, solar cells, junction field-effect transistors and integrated circuits like inverters and ring oscillators are discussed. The tremendous progress shows that bipolar oxide electronics has evolved from the exploration of various materials and heterostructures to the demonstration of functioning integrated circuits. Therefore a viable, facile and high performance technology is ready for further exploitation and performance optimization.

  19. Neuroinflammation in bipolar disorders

    OpenAIRE

    Georgios D. Kotzalidis; Elisa Ambrosi; Alessio Simonetti; Ilaria Cuomo; Antonio Del Casale; Matteo Caloro; Valeria Savoja; Chiara Rapinesi

    2015-01-01

    Recent literature based on peripheral immunity findings speculated that neuroinflammation, with its connection to microglial activation, is linked to bipolar disorder. The endorsement of the neuroinflammatory hypotheses of bipolar disorder requires the demonstration of causality, which requires longitudinal studies. We aimed to review the evidence for neuroinflammation as a pathogenic mechanism of the bipolar disorder. We carried out a hyper inclusive PubMed search using all appropriate neuro...

  20. Genetics Home Reference: bipolar disorder

    Science.gov (United States)

    ... Me Understand Genetics Home Health Conditions bipolar disorder bipolar disorder Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Bipolar disorder is a mental health condition that causes extreme ...

  1. Neuroimaging in Bipolar Disorder

    Directory of Open Access Journals (Sweden)

    Kemal Kara

    2013-03-01

    Full Text Available Bipolar disorder is characterized by recurrent attacks, significantly disrupts the functionality of a chronic mental disorder. Although there is growing number of studies on the neurobiological basis of the disorder, the pathophysiology has not yet been clearly understood. Structural and functional imaging techniques present a better understanding of the etiology of bipolar disorder and has contributed significantly to the development of the diagnostic approach. Recent developments in brain imaging modalities have let us learn more about the underlying abnormalities in neural systems of bipolar patients. Identification of objective biomarkers would help to determine the pathophysiology of bipolar disorder, a disorder which causes significant deterioration in neurocognitive and emotional areas.

  2. Phase segregation in Pb:GeSbTe chalcogenide system

    Science.gov (United States)

    Kumar, J.; Ahmad, M.; Chander, R.; Thangaraj, R.; Sathiaraj, T. S.

    2008-01-01

    Effect of Pb substitution on the amorphous-crystalline transformation temperature, optical band gap and crystalline structure of Ge{2}Sb{2}Te{5} has been studied. In Pb:GeSbTe chalcogenide films prepared by thermal evaporation, an amorphous to crystallization transition is observed at 124, 129, 136 and 138 °C in Pb{0}Ge{20}Sb{24}Te{56}, Pb{1.6}Ge{19}Sb{26}Te{54}, Pb{3}Ge{17}Sb{28}Te{53} and Pb{5}Ge{12}Sb{28}Te{55} respectively. XRD investigations of annealed samples reveal that Pb substitution retains NaCl type crystalline structure of GST but expands the lattice due to large atomic radii. The increase in amorphous-crystalline transformation temperature is followed with the increase in phase segregation. The optical gap shows marginal variations with composition.

  3. Management of bipolar depression

    Directory of Open Access Journals (Sweden)

    Jae Seung Chang

    2011-01-01

    Full Text Available Patients with bipolar disorder spend more time in a depressed than manic state, even with individualized treatment. To date, bipolar depression is often misdiagnosed and ineffectively managed both for acute episodes and residual symptoms. This review attempts to summarize the current status of available treatment strategies in the treatment of bipolar depression. For acute and prophylactic treatment, a substantial body of evidence supports the antidepressive efficacy of lithium for bipolar disorders and its antisuicidal effects. Among numerous anticonvulsants with mood-stabilizing properties, valproate and lamotrigine could be first-line options for bipolar depression. Due to receptor profile, mood-stabilizing properties of second-generation antipsychotics have been explored, and up to date, quetiapine and olanzapine appear to be a reasonable option for bipolar depression. The usefulness of antidepressants in bipolar depression is still controversial. Current guidelines generally recommend the cautious antidepressant use in combination with mood stabilizers to reduce the risk of mood elevation or cycle acceleration. Results from clinical trials on psychosocial intervention are promising, especially when integrated with pharmacotherapy. Most patients with bipolar depression need individualized and combined treatment, although the published evidence on this type of treatment strategy is limited. Future studies on the utility of currently available agents and modalities including psychosocial intervention are required.

  4. Magnetic bipolar transistor

    OpenAIRE

    Fabian, Jaroslav; Zutic, Igor; Sarma, S. Das

    2003-01-01

    A magnetic bipolar transistor is a bipolar junction transistor with one or more magnetic regions, and/or with an externally injected nonequilibrium (source) spin. It is shown that electrical spin injection through the transistor is possible in the forward active regime. It is predicted that the current amplification of the transistor can be tuned by spin.

  5. Properties of Bipolar Fuzzy Hypergraphs

    OpenAIRE

    M. Akram; Dudek, W. A.; Sarwar, S.

    2013-01-01

    In this article, we apply the concept of bipolar fuzzy sets to hypergraphs and investigate some properties of bipolar fuzzy hypergraphs. We introduce the notion of $A-$ tempered bipolar fuzzy hypergraphs and present some of their properties. We also present application examples of bipolar fuzzy hypergraphs.

  6. Neuroinflammation in bipolar disorders

    Directory of Open Access Journals (Sweden)

    Georgios D Kotzalidis

    2015-01-01

    Full Text Available Recent literature based on peripheral immunity findings speculated that neuroinflammation, with its connection to microglial activation, is linked to bipolar disorder. The endorsement of the neuroinflammatory hypotheses of bipolar disorder requires the demonstration of causality, which requires longitudinal studies. We aimed to review the evidence for neuroinflammation as a pathogenic mechanism of the bipolar disorder. We carried out a hyper inclusive PubMed search using all appropriate neuroinflammation-related terms and crossed them with bipolar disorder-related terms. The search produced 310 articles and the number rose to 350 after adding articles from other search engines and reference lists. Twenty papers were included that appropriately tackled the issue of the presence (but not of its pathophysiological role of neuroinflammation in bipolar disorder. Of these, 15 were postmortem and 5 were carried out in living humans. Most articles were consistent with the presence of neuroinflammation in bipolar disorder, but factors such as treatment may mask it. All studies were cross-sectional, preventing causality to be inferred. Thus, no inference can be currently made about the role of neuroinflammation in bipolar disorder, but a link is likely. The issue remains little investigated, despite an excess of reviews on this topic.

  7. Bipolarity and the relational division

    OpenAIRE

    Tamani, Nouredine; Lietard, Ludovic; Rocacher, Daniel

    2011-01-01

    International audience; A fuzzy bipolar relation is a relation defined by a fuzzy bipolar condition, which could be interpreted as an association of a constraint and a wish. In this context, the extension of the relational division operation to bipolarity is studied in this paper. Firstly, we define a bipolar division when the involved relations are crisp. Then, we define, from the semantic point of view, several forms of bipolar division when the involved relations are defined by fuzzy bipol...

  8. Thermal transport in amorphous materials: a review

    Science.gov (United States)

    Wingert, Matthew C.; Zheng, Jianlin; Kwon, Soonshin; Chen, Renkun

    2016-11-01

    Thermal transport plays a crucial role in performance and reliability of semiconductor electronic devices, where heat is mainly carried by phonons. Phonon transport in crystalline semiconductor materials, such as Si, Ge, GaAs, GaN, etc, has been extensively studied over the past two decades. In fact, study of phonon physics in crystalline semiconductor materials in both bulk and nanostructure forms has been the cornerstone of the emerging field of ‘nanoscale heat transfer’. On the contrary, thermal properties of amorphous materials have been relatively less explored. Recently, however, a growing number of studies have re-examined the thermal properties of amorphous semiconductors, such as amorphous Si. These studies, which included both computational and experimental work, have revealed that phonon transport in amorphous materials is perhaps more complicated than previously thought. For instance, depending on the type of amorphous materials, thermal transport occurs via three types of vibrations: propagons, diffusons, and locons, corresponding to the propagating, diffusion, and localized modes, respectively. The relative contribution of each of these modes dictates the thermal conductivity of the material, including its magnitude and its dependence on sample size and temperature. In this article, we will review the fundamental principles and recent development regarding thermal transport in amorphous semiconductors.

  9. Development, optimization and characterization of thin film materials and structures of tetrahedrally bonded amorphous semiconductors II. Final report; Entwicklung, Optimierung und Charakterisierung von Duennschichtmaterialien und -strukturen sowie Grenzflaechen fuer photovoltaische Anwendungen tetraedrisch gebundener Halbleiterschichten II (Basisforschung a-Si/a-Ge). Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, B.; Oechsner, H.

    1998-07-31

    In a comprehensive study we have investigated the effect of the most important deposition parameters on the electronic and microstructural properties of a-Si:H films, deposited by the thermocatalytic CVD, also called hot wire (HW) CVD. This method was found to be an attractive alternative to the plasma enhanced CVD realizing the deposition of amorphous and microcrystalline semiconductor films for solar cell application. Using relatively simple equipment device quality material can be deposited with high rates and large flexibility. Due to results obtained by thin film growth investigations employing the in-situ ellipsometry the material quality could be optimized in terms of microstructural properties. With the invention of a special process control, the microstructural interface engineering, the thermocatalytic CVD a-Si:H material was integrated in solar cells with a conversion efficiency of up to 10.2%. This value was obtained without using highly reflecting rear contacts and, even more, two until now unavoidable `air breaks`. The knowledge about the relationship between microstructure and stability, which was gained during the investigation within the project, enabled us to open up new ways to reduce the degradation of solar cells containing HW-a-Si:H. In that way solar cells with the same initial conversion efficiency but improved stability have been produced, depositing the HW-a-Si:H i-layer with moderate H-dilution. Also {mu}c-Si:H, a-SiGe:H, and a-Ge:H films could be deposited with large rates and high quality applying the TCCVD method. These materials which are important for stacked cell application could be integrated with good (a-SiGe:H) and less good effort ({mu}c-Si:H, a-Ge:H) into solar cell structures. (orig.) [Deutsch] Intensive und grundlegende Untersuchungen im Rahmen dieses Vorhabens haben ergeben, dass sog. `Hot wire (HW)` oder `thermokatalytische (TC)` CVD-Verfahren eine aeusserst attraktive Alternative zur Abscheidung von amorphem und

  10. Hydrogen Bonding in Hydrogenated Amorphous Germanium

    Institute of Scientific and Technical Information of China (English)

    M.S.Abo-Ghazala; S. Al Hazmy

    2004-01-01

    Thin films of hydrogenated amorphous germanium (a-Ge:H) were prepared by radio frequency glow discharge deposition at various substrate temperatures. The hydrogen distribution and bonding structure in a-Ge:H were discussed based on infrared absorption data. The correlation between infrared absorption spectra and hydrogen effusion measurements was used to determine the proportionality constant for each vibration mode of the Ge-H bonds. The results reveal that the bending mode appearing at 835 cm?1 is associated with the Ge-H2 (dihydride) groups on the internal surfaces of voids. While 1880 cm?1 is assigned to vibrations of Ge-H (monohydride) groups in the bulk, the 2000 cm?1 stretching mode is attributed to Ge-H and Ge-H2 bonds located on the surfaces of voids. For films associated with bending modes in the infrared spectra, the proportionality constant values of the stretching modes near 1880 and 2000 cm?1 are found to be lower than those of films which had no corresponding bending modes.

  11. Lightweight bipolar storage battery

    Science.gov (United States)

    Rowlette, John J. (Inventor)

    1992-01-01

    An apparatus [10] is disclosed for a lightweight bipolar battery of the end-plate cell stack design. Current flow through a bipolar cell stack [12] is collected by a pair of copper end-plates [16a,16b] and transferred edgewise out of the battery by a pair of lightweight, low resistance copper terminals [28a,28b]. The copper terminals parallel the surface of a corresponding copper end-plate [16a,16b] to maximize battery throughput. The bipolar cell stack [12], copper end-plates [16a,16b] and copper terminals [28a,28b] are rigidly sandwiched between a pair of nonconductive rigid end-plates [20] having a lightweight fiber honeycomb core which eliminates distortion of individual plates within the bipolar cell stack due to internal pressures. Insulating foam [30] is injected into the fiber honeycomb core to reduce heat transfer into and out of the bipolar cell stack and to maintain uniform cell performance. A sealed battery enclosure [ 22] exposes a pair of terminal ends [26a,26b] for connection with an external circuit.

  12. Bipolar Affective Disorder and Migraine

    Directory of Open Access Journals (Sweden)

    Birk Engmann

    2012-01-01

    Full Text Available This paper consists of a case history and an overview of the relationship, aetiology, and treatment of comorbid bipolar disorder migraine patients. A MEDLINE literature search was used. Terms for the search were bipolar disorder bipolar depression, mania, migraine, mood stabilizer. Bipolar disorder and migraine cooccur at a relatively high rate. Bipolar II patients seem to have a higher risk of comorbid migraine than bipolar I patients have. The literature on the common roots of migraine and bipolar disorder, including both genetic and neuropathological approaches, is broadly discussed. Moreover, bipolar disorder and migraine are often combined with a variety of other affective disorders, and, furthermore, behavioural factors also play a role in the origin and course of the diseases. Approach to treatment options is also difficult. Several papers point out possible remedies, for example, valproate, topiramate, which acts on both diseases, but no first-choice treatments have been agreed upon yet.

  13. Depression and Bipolar Support Alliance

    Science.gov (United States)

    Depression and Bipolar Support Alliance Crisis Hotline Information Coping with a Crisis Suicide Prevention Information Psychiatric Hospitalization ... sign-up Education info, training, events Mood Disorders Depression Bipolar Disorder Anxiety Screening Center Co-occurring Illnesses/ ...

  14. Childhood trauma in bipolar disorder.

    OpenAIRE

    Watson, S; Gallagher, P.; Dougall, D.; Porter, R.; Moncrieff, J; Ferrier, I N; Young, A.H.

    2014-01-01

    Objective:There has been little investigation of early trauma in bipolar disorder despite evidence that stress impacts on the course of this illness. We aimed to compare the rates of childhood trauma in adults with bipolar disorder to a healthy control group, and to investigate the impact of childhood trauma on the clinical course of bipolar disorder.Methods:Retrospective assessment of childhood trauma was conducted using the Childhood Trauma Questionnaire (CTQ) in 60 outpatients with bipolar...

  15. Photoemission studies of amorphous silicon induced by P + ion implantation

    Science.gov (United States)

    Petö, G.; Kanski, J.

    1995-12-01

    An amorphous Si layer was formed on a Si (1 0 0) surface by P + implantation at 80 keV. This layer was investigated by means of photoelectron spectroscopy. The resulting spectra are different from earlier spectra on amorphous Si prepared by e-gun evaporation or cathode sputtering. The differences consist of a decreased intensity in the spectral region corresponding to p-states, and appearace of new states at higher binding energy. Qualitativity similar results have been reported for Sb implanted amorphous Ge and the modification seems to be due to the changed short range order.

  16. The origin of the resistance change in GeSbTe films

    Science.gov (United States)

    Jang, Moon Hyung; Park, Seung Jong; Park, Sung Jin; Cho, Mann-Ho; Kurmaev, E. Z.; Finkelstein, L. D.; Chang, Gap Soo

    2010-10-01

    Amorphous Ge2Sb2Te5 (a-GST) films were deposited by ion beam sputtering deposition. Extended x-ray absorption fine structure (EXAFS) data confirmed the existence of the Ge-Ge homopolar bonds in the films. Raman spectra also indicated that the Ge tetrahedral coordination in the a-GST film disappeared after an annealing treatment above 220 °C. Resonantly excited Ge L2,3 x-ray emission spectra (which probe occupied Ge 3d4s-electronic states) show that the phase change from the amorphous to crystalline state is accompanied by a reduction in the Ge I(L2)/I(L3) intensity ratio due to a L2L3N Coster-Kronig transition, indicating that the number of carriers is increased in the Ge 4sp valence state. These findings constitute direct evidence for the contribution of the Ge electronic states to the resistivity change.

  17. Study of Nanotribology of Different Amorphous GeSbTe Thin Films with Lateral Force Microscope (LFM)%用侧向力显微镜对不同非晶态GeSbTe薄膜的摩擦性能研究

    Institute of Scientific and Technical Information of China (English)

    解国新; 丁建宁; 范真; 付永忠; 朱守星

    2005-01-01

    采用侧向力显微镜研究了磁控溅射方法制备的GeSbTe薄膜在大气环境中的纳米级摩擦性能,考虑了相对湿度、扫描速度及表面粗糙度对其摩擦性能的影响,对比不同成分的GeSbTe薄膜的摩擦特性.结果表明:在相对湿度较大时,扫描速度对针尖和GeSbTe薄膜之间的摩擦力影响很大;在其它条件相同、外加载荷较大时,同一载荷下的摩擦力与表面粗糙度呈线性关系,但在外加载荷较小的情况下,二者呈现非线性变化规律;相对湿度对Ge2Sb2Te5薄膜和针尖的粘附力影响较GeSb2Te4薄膜弱,且粘附力使得摩擦系数减小;在同一相对湿度下,由于薄膜成分的变化导致硬度不同,其对薄膜的摩擦性能也有一定影响.

  18. Is Cognitive Style Bipolar?

    Science.gov (United States)

    Schroeder, David H.

    This study assessed the bipolarity of cognitive style for 970 clients of the Johnson O'Connor Research Foundation, a vocational guidance service. The 462 male and 508 female examinees were aged 14 to 65 years, with a median age of 24 years. Three cognitive style tests were investigated: (1) the Kagan Matching Familiar Figures Test (KMFFT); (2) the…

  19. Effect of Ge Content on the Formation of Ge Nanoclusters in Magnetron-Sputtered GeZrOx-Based Structures.

    Science.gov (United States)

    Khomenkova, L; Lehninger, D; Kondratenko, O; Ponomaryov, S; Gudymenko, O; Tsybrii, Z; Yukhymchuk, V; Kladko, V; von Borany, J; Heitmann, J

    2017-12-01

    Ge-rich ZrO2 films, fabricated by confocal RF magnetron sputtering of pure Ge and ZrO2 targets in Ar plasma, were studied by multi-angle laser ellipsometry, Raman scattering, Auger electron spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction for varied deposition conditions and annealing treatments. It was found that as-deposited films are homogeneous for all Ge contents, thermal treatment stimulated a phase separation and a formation of crystalline Ge and ZrO2. The "start point" of this process is in the range of 640-700 °C depending on the Ge content. The higher the Ge content, the lower is the temperature necessary for phase separation, nucleation of Ge nanoclusters, and crystallization. Along with this, the crystallization temperature of the tetragonal ZrO2 exceeds that of the Ge phase, which results in the formation of Ge crystallites in an amorphous ZrO2 matrix. The mechanism of phase separation is discussed in detail.

  20. [Amorphization in pharmaceutical technology].

    Science.gov (United States)

    Révész, Piroska; Laczkovich, Orsolya; Eros, István

    2004-01-01

    The amorphization of crystalline active ingredients may be necessary because of the polymorphism of the active substance, the poor water-solubility of the drug material, difficult processing in the crystalline form and the taking out of a patent for a new (amorphous) form. This article introduces protocols for amorphization, which use methods traditionally applied in pharmaceutical technology. The protocols involve three possible routes: solvent methods, hot-melt technologies and milling procedures. With this presentation, the authors suggest help for practising experts to find the correct amorphization method.

  1. ON BIPOLAR SINGLE VALUED NEUTROSOPHIC GRAPHS

    OpenAIRE

    Said Broumi; Mohamed Talea; Assia Bakali; Florentin Smarandache

    2016-01-01

    In this article, we combine the concept of bipolar neutrosophic set and graph theory. We introduce the notions of bipolar single valued neutrosophic graphs, strong bipolar single valued neutrosophic graphs, complete bipolar single valued neutrosophic graphs, regular bipolar single valued neutrosophic graphs and investigate some of their related properties. 

  2. 用气态源分子束外延生长法制备Si/SiGe/Si nPn异质结双极晶体管%Growth of Si/SiGe/Si Heterojunction Bipolar Transistors by Gas-Source Molecular Beam Epitaxy

    Institute of Scientific and Technical Information of China (English)

    刘学锋; 李晋闽; 孔梅影; 黄大定; 李建平; 林兰英

    2000-01-01

    用气态源分子束外延法制备了Si/SiGe/Si npn异质结双极晶体管.晶体管基区Ge组分为0.12,B掺杂浓度为1.5×101 9cm-3, SiGe合金厚度约45nm.直流特性测试表明,共发射极直流放大倍数约50,击穿电压VCE约9V;射频特性测试结果表明,晶体管的截止频率为7GHz,最高振荡频率为2.5GHz.

  3. Properties Of Gallium-doped Hydrogenated Amorphous Germanium

    OpenAIRE

    1995-01-01

    The effects of adding small quantities of gallium atoms to hydrogenated amorphous germanium (a-Ge:H) on its dark-conductivity, band-gap, electronic density of states and the hydrogen bonding, were studied in detail by dark-conductivity, optical and infrared-transmission, and photothermal- deflection-spectroscopy measurements. Films of a-Ge:H having relative Ga atomic concentrations ranging between 3×10-5 and 1×10-2 were deposited by the cosputtering of solid Ge and Ga targets in a rf-plasma s...

  4. Radiation damage of SiGe HBT Technologies at different bias configurations

    CERN Document Server

    Ullán, M; Lozano, M; Pellegrini, G; Knoll, D; Heinemann, B

    2008-01-01

    SiGe BiCMOS technologies are being proposed for the Front-end readout of the detectors in the middle region of the ATLAS-Upgrade. The radiation hardness of the SiGe bipolar transistors is being assessed for this application through irradiations with different particles. Biasing conditions during irradiation of bipolar transistors or circuits have an influence on the damage and there is a risk of erroneous results. We have performed several irradiation experiments of SiGe devices from IHP in different bias conditions. We have observed a systematic trend in gamma irradiations, showing a smaller damage in transistors irradiated biased compared to shorted or floating terminals.

  5. Epilepsy and bipolar disorder.

    Science.gov (United States)

    Knott, Sarah; Forty, Liz; Craddock, Nick; Thomas, Rhys H

    2015-11-01

    It is well recognized that mood disorders and epilepsy commonly co-occur. Despite this, our knowledge regarding the relationship between epilepsy and bipolar disorder is limited. Several shared features between the two disorders, such as their episodic nature and potential to run a chronic course, and the efficacy of some antiepileptic medications in the prophylaxis of both disorders, are often cited as evidence of possible shared underlying pathophysiology. The present paper aims to review the bidirectional associations between epilepsy and bipolar disorder, with a focus on epidemiological links, evidence for shared etiology, and the impact of these disorders on both the individual and wider society. Better recognition and understanding of these two complex disorders, along with an integrated clinical approach, are crucial for improved evaluation and management of comorbid epilepsy and mood disorders.

  6. Molecules in Bipolar Outflows

    CERN Document Server

    Tafalla, Mario

    2012-01-01

    Bipolar outflows constitute some of the best laboratories to study shock chemistry in the interstellar medium. A number of molecular species have their abundance enhanced by several orders of magnitude in the outflow gas, likely as a combined result of dust mantle disruption and high temperature gas chemistry, and therefore become sensitive indicators of the physical changes taking place in the shock. Identifying these species and understanding their chemical behavior is therefore of high interest both to chemical studies and to our understanding of the star-formation process. Here we review some of the recent progress in the study of the molecular composition of bipolar outflows, with emphasis in the tracers most relevant for shock chemistry. As we discuss, there has been rapid progress both in characterizing the molecular composition of certain outflows as well as in modeling the chemical processes likely involved. However, a number of limitations still affect our understanding of outflow chemistry. These i...

  7. Life expectancy in bipolar disorder

    DEFF Research Database (Denmark)

    Kessing, Lars Vedel; Vradi, Eleni; Andersen, Per Kragh

    2015-01-01

    OBJECTIVE: Life expectancy in patients with bipolar disorder has been reported to be decreased by 11 to 20 years. These calculations are based on data for individuals at the age of 15 years. However, this may be misleading for patients with bipolar disorder in general as most patients have a later...... onset of illness. The aim of the present study was to calculate the remaining life expectancy for patients of different ages with a diagnosis of bipolar disorder. METHODS: Using nationwide registers of all inpatient and outpatient contacts to all psychiatric hospitals in Denmark from 1970 to 2012 we...... remaining life expectancy in bipolar disorder and that of the general population decreased with age, indicating that patients with bipolar disorder start losing life-years during early and mid-adulthood. CONCLUSIONS: Life expectancy in bipolar disorder is decreased substantially, but less so than previously...

  8. Bipolar intimal tacking device.

    Science.gov (United States)

    Gross, C E; Williams, G

    1984-09-01

    A bipolar electrocoagulating device has been designed to thermally tack arterial intimal flaps to the artery wall. The device was tested on intimal flaps created in the rabbit descending aorta. The vascular segments were tested for patency and the thermal tack points were examined on a scanning electron microscope. The tack points were shown to be of sufficient tensile strength and to have minimal thrombogenicity.

  9. Density functional simulations of Sb-rich GeSbTe phase change alloys

    Science.gov (United States)

    Gabardi, S.; Caravati, S.; Bernasconi, M.; Parrinello, M.

    2012-09-01

    We generated models of the amorphous phase of Sb-rich GeSbTe phase change alloys by quenching from the melt within density functional molecular dynamics. We considered the two compositions Ge1Sb1Te1 and Ge2Sb4Te5. Comparison with previous results on the most studied Ge2Sb2Te5 allowed us to draw some conclusions on the dependence of the structural properties of the amorphous phase on the alloy composition. Vibrational and electronic properties were also scrutinized. Phonons at high frequencies above 200 cm-1 are localized in tetrahedra around Ge atoms in Sb-rich compounds as well as in Ge2Sb2Te5. All compounds are semiconducting in the amorphous phase, with a band gap in the range 0.7-1.0 eV.

  10. Density functional simulations of Sb-rich GeSbTe phase change alloys.

    Science.gov (United States)

    Gabardi, S; Caravati, S; Bernasconi, M; Parrinello, M

    2012-09-26

    We generated models of the amorphous phase of Sb-rich GeSbTe phase change alloys by quenching from the melt within density functional molecular dynamics. We considered the two compositions Ge(1)Sb(1)Te(1) and Ge(2)Sb(4)Te(5). Comparison with previous results on the most studied Ge(2)Sb(2)Te(5) allowed us to draw some conclusions on the dependence of the structural properties of the amorphous phase on the alloy composition. Vibrational and electronic properties were also scrutinized. Phonons at high frequencies above 200 cm(-1) are localized in tetrahedra around Ge atoms in Sb-rich compounds as well as in Ge(2)Sb(2)Te(5). All compounds are semiconducting in the amorphous phase, with a band gap in the range 0.7-1.0 eV.

  11. [Creativity and bipolar disorder].

    Science.gov (United States)

    Maçkalı, Zeynep; Gülöksüz, Sinan; Oral, Timuçin

    2014-01-01

    The relationship between creativity and bipolar disorder has been an intriguing topic since ancient times. Early studies focused on describing characteristics of creative people. From the last quarter of the twentieth century, researchers began to focus on the relationship between mood disorders and creativity. Initially, the studies were based on biographical texts and the obtained results indicated a relationship between these two concepts. The limitations of the retrospective studies led the researchers to develop systematic investigations into this area. The systematic studies that have focused on artistic creativity have examined both the prevalence of mood disorders and the creative process. In addition, a group of researchers addressed the relationship in terms of affective temperaments. Through the end of the 90's, the scope of creativity was widened and the notion of everyday creativity was proposed. The emergence of this notion led researchers to investigate the associations of the creative process in ordinary (non-artist) individuals. In this review, the descriptions of creativity and creative process are mentioned. Also, the creative process is addressed with regards to bipolar disorder. Then, the relationship between creativity and bipolar disorder are evaluated in terms of aforementioned studies (biographical, systematic, psychobiographical, affective temperaments). In addition, a new model, the "Shared Vulnerability Model" which was developed to explain the relationship between creativity and psychopathology is introduced. Finally, the methodological limitations and the suggestions for resolving these limitations are included.

  12. Childhood trauma in bipolar disorder

    OpenAIRE

    Watson, Stuart; Gallagher, Peter; Dougall, Dominic; Porter, Richard; Moncrieff, Joanna; Ferrier, I Nicol; Young, Allan H.

    2014-01-01

    Objective: There has been little investigation of early trauma in bipolar disorder despite evidence that stress impacts on the course of this illness. We aimed to compare the rates of childhood trauma in adults with bipolar disorder to a healthy control group, and to investigate the impact of childhood trauma on the clinical course of bipolar disorder. Methods: Retrospective assessment of childhood trauma was conducted using the Childhood Trauma Questionnaire (CTQ) in 60 outpatients with bipo...

  13. Bipolar Disorder and Alcoholism: Are They Related?

    Science.gov (United States)

    ... Is there a connection between bipolar disorder and alcoholism? Answers from Daniel K. Hall-Flavin, M.D. Bipolar disorder and alcoholism often occur together. Although the association between bipolar ...

  14. Bipolar Disorder in Children and Teens

    Science.gov (United States)

    ... is in crisis. What do I do? Share Bipolar Disorder in Children and Teens Download PDF Download ePub ... brochure will give you more information. What is bipolar disorder? Bipolar disorder is a serious brain illness. It ...

  15. Bipolar Disorder and Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Sermin Kesebir

    2010-04-01

    Full Text Available Comorbid endocrine and cardiovascular situations with bipolar disorder usually result from the bipolar disorder itself or as a consequence of its treatment. With habits and lifestyle, genetic tendency and side effects, this situation is becoming more striking. Subpopulations of bipolar disorders patients should be considered at high risk for diabetes mellitus. The prevalence of diabetes mellitus in bipolar disorder may be three times greater than in the general population. Comorbidity of diabetes causes a pathophysiological overlapping in the neurobiological webs of bipolar cases. Signal mechanisms of glycocorticoid/insulin and immunoinflammatory effector systems are junction points that point out the pathophysiology between bipolar disorder and general medical cases susceptible to stress. Glycogen synthetase kinase (GSK-3 is a serine/treonine kinase and inhibits the transport of glucose stimulated by insulin. It is affected in diabetes, cancer, inflammation, Alzheimer disease and bipolar disorder. Hypoglycemic effect of lithium occurs via inhibiting glycogen synthetase kinase. When comorbid with diabetes, the other disease -for example bipolar disorder, especially during its acute manic episodes-, causes a serious situation that presents its influences for a lifetime. Choosing pharmacological treatment and treatment adherence are another important interrelated areas. The aim of this article is to discuss and review the etiological, clinical and therapeutic properties of diabetes mellitus and bipolar disorder comorbidity.

  16. Trehalose amorphization and recrystallization.

    Science.gov (United States)

    Sussich, Fabiana; Cesàro, Attilio

    2008-10-13

    The stability of the amorphous trehalose prepared by using several procedures is presented and discussed. Amorphization is shown to occur by melting (T(m)=215 degrees C) or milling (room temperature) the crystalline anhydrous form TRE-beta. Fast dehydration of the di-hydrate crystalline polymorph, TRE-h, also produces an amorphous phase. Other dehydration procedures of TRE-h, such as microwave treatment, supercritical extraction or gentle heating at low scan rates, give variable fractions of the polymorph TRE-alpha, that undergo amorphization upon melting (at lower temperature, T(m)=130 degrees C). Additional procedures for amorphization, such as freeze-drying, spray-drying or evaporation of trehalose solutions, are discussed. All these procedures are classified depending on the capability of the undercooled liquid phase to undergo cold crystallization upon heating the glassy state at temperatures above the glass transition temperature (T(g)=120 degrees C). The recrystallizable amorphous phase is invariably obtained by the melt of the polymorph TRE-alpha, while other procedures always give an amorphous phase that is unable to crystallize above T(g). The existence of two different categories is analyzed in terms of the transformation paths and the hypothesis that the systems may exhibit different molecular mobilities.

  17. Investigation of crystallization and amorphization dynamics of phase-change thin films by subnanosecond laser pulses.

    Science.gov (United States)

    Kieu, Khanh; Narumi, Kenji; Mansuripur, Masud

    2006-10-20

    We report experimental results on amorphization and crystallization dynamics of reversible phase-change (PC) thin-film samples, GeSbTe and GeBiTe, for optical disk data storage. The investigation was conducted with subnanosecond laser pulses using a pump-and-probe configuration. Amorphization of the crystalline films could be achieved with a single subnanosecond laser pulse; the amorphization dynamics follow closely the temperature kinetics induced in the irradiated spot. As for crystallization of the samples initially in the amorphous state, a single subnanosecond pulse was found to be insufficient to fully crystallize the irradiated spot, but we could crystallize the PC film (in the area under the focused spot) by applying multiple short pulses. Our multipulse studies reveal that the GeSbTe crystallization is dominated by the growth of nuclei whose initial formation is slow but, once formed, their subsequent growth (under a sequence of subnanosecond pulses) happens quickly. In the case of GeBiTe samples, the crystalline nuclei appear to be present in the material initially, as they grow immediately upon illumination with laser pulses. Whereas our amorphous GeSbTe samples required approximately 200 pulses for full crystallization, for the GeBiTe samples approximately 15 pulses sufficed.

  18. Amorphous semiconductor sample preparation for transmission EXAFS measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ridgway, M.C.; Glover, C.J.; Tan, H.H. [Australian National Univ., Canberra (Australia). Dept. of Electronic Materials Engineering] [and others

    1998-12-31

    A novel methodology has been developed for the preparation of amorphous semiconductor samples for use in transmission extended x-ray absorption fine structure (EXAFS) measurements. Epitaxial heterostructures were fabricated by metal organic chemical vapor deposition (group III-Vs) or molecular beam epitaxy (group IVs). An epitaxial layer of {approximately} 2 {micro}m thickness was separated from the underlying substrate by selective chemical etching of an intermediate sacrificial layer. Ion implantation was utilized to amorphize the epitaxial layer either before or after selective chemical etching. The resulting samples were both stoichiometric and homogeneous in contrast to those produced by conventional techniques. The fabrication of amorphous GaAs, InP, In{sub 0.53}Ga{sub 0.47}As and Si{sub x}Ge{sub 1{minus}x} samples is described. Furthermore, EXAFS measurements comparing both fluorescence and transmission detection, and crystalline and amorphized GaAs, are shown.

  19. Amorphous iron (II) carbonate

    DEFF Research Database (Denmark)

    Sel, Ozlem; Radha, A.V.; Dideriksen, Knud;

    2012-01-01

    exothermic than that of amorphous calcium carbonate (ACC). This suggests that enthalpy of crystallization in carbonate systems is ionic-size controlled, which may have significant implications in a wide variety of conditions, including geological sequestration of anthropogenic carbon dioxide.......Abstract The synthesis, characterization and crystallization energetics of amorphous iron (II) carbonate (AFC) are reported. AFC may form as a precursor for siderite (FeCO3). The enthalpy of crystallization (DHcrys) of AFC is similar to that of amorphous magnesium carbonate (AMC) and more...

  20. Electronic transport in amorphous phase-change materials

    Energy Technology Data Exchange (ETDEWEB)

    Luckas, Jennifer Maria

    2012-09-14

    Phase change materials combine a pronounced contrast in resistivity and reflectivity between their disordered amorphous and ordered crystalline state with very fast crystallization kinetics. Due to this exceptional combination of properties phase-change materials find broad application in non-volatile optical memories such as CD, DVD or Bluray Disc. Furthermore, this class of materials demonstrates remarkable electrical transport phenomena in their disordered state, which have shown to be crucial for their application in electronic storage devices. The threshold switching phenomenon denotes the sudden decrease in resistivity beyond a critical electrical threshold field. The threshold switching phenomenon facilitates the phase transitions at practical small voltages. Below this threshold the amorphous state resistivity is thermally activated and is observed to increase with time. This effect known as resistance drift seriously hampers the development of multi-level storage devices. Hence, understanding the physical origins of threshold switching and resistance drift phenomena is crucial to improve non-volatile phase-change memories. Even though both phenomena are often attributed to localized defect states in the band gap, the defect state density in amorphous phase-change materials has remained poorly studied. Starting from a brief introduction of the physics of phase-change materials this thesis summarizes the most important models behind electrical switching and resistance drift with the aim to discuss the role of localized defect states. The centerpiece of this thesis is the investigation of defects state densities in different amorphous phase-change materials and electrical switching chalcogenides. On the basis of Modulated Photo Current (MPC) Experiments and Photothermal Deflection Spectroscopy, a sophisticated band model for the disordered phase of the binary phase-change alloy GeTe has been developed. By this direct experimental approach the band-model for a-Ge

  1. An Electrochromic Bipolar Membrane Diode.

    Science.gov (United States)

    Malti, Abdellah; Gabrielsson, Erik O; Crispin, Xavier; Berggren, Magnus

    2015-07-01

    Conducting polymers with bipolar membranes (a complementary stack of selective membranes) may be used to rectify current. Integrating a bipolar membrane into a polymer electrochromic display obviates the need for an addressing backplane while increasing the device's bistability. Such devices can be made from solution-processable materials.

  2. Genetics of bipolar disorder

    Directory of Open Access Journals (Sweden)

    Kerner B

    2014-02-01

    Full Text Available Berit Kerner Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, USA Abstract: Bipolar disorder is a common, complex genetic disorder, but the mode of transmission remains to be discovered. Many researchers assume that common genomic variants carry some risk for manifesting the disease. The research community has celebrated the first genome-wide significant associations between common single nucleotide polymorphisms (SNPs and bipolar disorder. Currently, attempts are under way to translate these findings into clinical practice, genetic counseling, and predictive testing. However, some experts remain cautious. After all, common variants explain only a very small percentage of the genetic risk, and functional consequences of the discovered SNPs are inconclusive. Furthermore, the associated SNPs are not disease specific, and the majority of individuals with a “risk” allele are healthy. On the other hand, population-based genome-wide studies in psychiatric disorders have rediscovered rare structural variants and mutations in genes, which were previously known to cause genetic syndromes and monogenic Mendelian disorders. In many Mendelian syndromes, psychiatric symptoms are prevalent. Although these conditions do not fit the classic description of any specific psychiatric disorder, they often show nonspecific psychiatric symptoms that cross diagnostic boundaries, including intellectual disability, behavioral abnormalities, mood disorders, anxiety disorders, attention deficit, impulse control deficit, and psychosis. Although testing for chromosomal disorders and monogenic Mendelian disorders is well established, testing for common variants is still controversial. The standard concept of genetic testing includes at least three broad criteria that need to be fulfilled before new genetic tests should be introduced: analytical validity, clinical validity, and clinical utility. These criteria are

  3. Scientific attitudes towards bipolar disorders

    Directory of Open Access Journals (Sweden)

    Mohammad-Hossein Biglu

    2014-02-01

    Full Text Available Introduction: Bipolar disorder is a psychiatric condition that is also called manic-depressive disease. It causes unusual changes in mood, energy, activity levels, and the ability to carry out day-to-day tasks. In the present study, 3 sets of data were considered and analyzed: first, all papers categorized under Bipolar Disorders in Science Citation Index Expanded (SCI-E database through 2001-2011; second, papers published by the international journal of Bipolar Disorders indexed in SCI-E during a period of 11 years; and third, all papers distributed by the international journal of Bipolar Disorders indexed in MEDLINE during the period of study. Methods: The SCI-E database was used to extract all papers indexed with the topic of Bipolar Disorders as well as all papers published by The International Journal of Bipolar Disorders. Extraction of data from MEDLINE was restricted to the journals name from setting menu. The Science of Science Tool was used to map the co-authorship network of papers published by The International Journal of Bipolar Disorders through 2009-2011. Results: Analysis of data showed that the majority of publications in the subject area of bipolar disorders indexed in SCI-E were published by The International Journal of Bipolar Disorders. Although journal articles consisted of 59% of the total publication type in SCI-E, 65% of publications distributed by The Journal of Bipolar Disorders were in the form of meetingabstracts. Journal articles consisted of only 23% of the total publications. USA was the leading country regarding sharing data in the field of bipolar disorders followed by England, Canada, and Germany. Conclusion: The editorial policy of The International Journal of Bipolar Disorders has been focused on new themes and new ways of researching in the subject area of bipolar disorder. Regarding the selection of papers for indexing, the SCI-E database selects data more comprehensively than MEDLINE. The number of papers

  4. [Treatment of bipolar disorder].

    Science.gov (United States)

    Barde, Michael; Bellivier, Frank

    2014-11-01

    Bipolar disorder is a chronic pathology whose management must lead to limit the social, professional and family impacts as well as suicidal risk. The treatment of acute episodes and prophylaxis is based on mood stabilizer treatments whose lithium is a leader. They will be chosen according to the background and history of the disease. Anti-depressants must be used with care to minimize the risk of manic episode and the induction of rapid cycles. The prognosis is not solving major episodes but avoiding major mood episodes. The management of residual symptoms (especially neuro-cognitive) is also a major challenge prognosis and justifies the implementation of adjuvant psychotherapeutic strategies.

  5. Nature of defects and gap states in GeTe model phase change materials

    Science.gov (United States)

    Huang, B.; Robertson, J.

    2012-03-01

    The electrical storage mechanism in GeSbTe phase change materials is discussed in terms of their gap states using GeTe as a model system. The lowest energy defect in crystalline rhombohedral GeTe phase is the Ge vacancy, because it reconstructs along the resonant bonding directions. The lowest energy in amorphous GeTe is the divalent Te atom, which creates overlapping band-tail states that pin Fermi level EF near midgap. In contrast, the lowest cost defect in disordered phase in GeSbTe superlattices is the Te interstitial whose negative correlation energy pins EF near midgap.

  6. Bipolar Disorder and Childhood Trauma

    Directory of Open Access Journals (Sweden)

    Evrim Erten

    2015-06-01

    Full Text Available Bipolar disorder is a chronic disorder in which irregular course of depressive, mania or mixed episodes or a complete recovery between episodes can be observed. The studies about the effects of traumatic events on bipolar disorder showed that they had significant and long-term effects on the symptoms of the disorder. Psychosocial stress might change the neurobiology of bipolar disorder over time. The studies revealed that the traumatic events could influence not only the onset of the disorder but also the course of the disorder and in these patients the rate of suicide attempt and comorbid substance abuse might increase. Bipolar patients who had childhood trauma had an earlier onset, higher number of episodes and comorbid disorders. In this review, the relationship between childhood trauma and bipolar disorder is reviewed. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2015; 7(2: 157-165

  7. Epidemiology in Pediatric Bipolar Disorder

    Directory of Open Access Journals (Sweden)

    Caner Mutlu

    2015-12-01

    Full Text Available Childhood and adolescent bipolar disorder diagnosis has been increasing recently. Since studies evaluating attempted suicide rates in children and adolescents have shown bipolarity to be a significant risk factor, diagnosis and treatment of bipolarity has become a very important issue. Since there is a lack of specific diagnostic criteria for especially preadolescent samples and evaluations are made mostly symptomatically, suspicions about false true diagnosis and increased prevalence rates have emerged. This situation leads to controversial data about the prevalence rates of bipolar disorder in children and adolescents. The aim of this article is to review the prevalence of childhood and adolescent bipolar disorder in community, inpatient and outpatient based samples in literature.

  8. Amorphous Solid Water:

    DEFF Research Database (Denmark)

    Wenzel, Jack; Linderstrøm-Lang, C. U.; Rice, Stuart A.

    1975-01-01

    The structure factor of amorphous solid D2O deposited from the vapor at 10°K has been obtained by measuring the neutron diffraction spectrum in the wave vector transfer from 0.8 to 12.3 reciprocal angstroms. The results indicate that the phase investigated is amorphous and has a liquiid-like stru......The structure factor of amorphous solid D2O deposited from the vapor at 10°K has been obtained by measuring the neutron diffraction spectrum in the wave vector transfer from 0.8 to 12.3 reciprocal angstroms. The results indicate that the phase investigated is amorphous and has a liquiid...

  9. Amorphous pharmaceutical solids.

    Science.gov (United States)

    Vranić, Edina

    2004-07-01

    Amorphous forms are, by definition, non-crystalline materials which possess no long-range order. Their structure can be thought of as being similar to that of a frozen liquid with the thermal fluctuations present in a liquid frozen out, leaving only "static" structural disorder. The amorphous solids have always been an essential part of pharmaceutical research, but the current interest has been raised by two developments: a growing attention to pharmaceutical solids in general, especially polymorphs and solvates and a revived interest in the science of glasses and the glass transition. Amorphous substances may be formed both intentionally and unintentionally during normal pharmaceutical manufacturing operations. The properties of amorphous materials can be exploited to improve the performance of pharmaceutical dosage forms, but these properties can also give rise to unwanted effects that need to be understood and managed in order for the systems to perform as required.

  10. Innovative Characterization of Amorphous and Thin-Film Silicon for Improved Module Performance: 1 February 2005 - 31 July 2008

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, P. C.; Williams, G. A.

    2009-09-01

    Electron spin resonance and nuclear magnetic resonance was done on amorphous silicon samples (modules with a-Si:H and a-SixGe1-x:H intrinsic layer) to study defects that contribute to Staebler-Wronski effect.

  11. Structural evolution of Ge-rich Si{sub 1−x}Ge{sub x} films deposited by jet-ICPCVD

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu; Yang, Meng; Wang, Gang [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Wei, Xiaoxu; Wang, Junzhuan; Li, Yun; Zheng, Youdou; Shi, Yi, E-mail: yshi@nju.edu.cn [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Micro-structures, Nanjing University, Nanjing 210093 (China); Zou, Zewen [College of Physics and Electronics Information, Anhui Normal University, Wuhu 241000 (China)

    2015-11-15

    Amorphous Ge-rich Si{sub 1−x}Ge{sub x} films with local Ge-clustering were deposited by dual-source jet-type inductively coupled plasma chemical-vapor deposition (jet-ICPCVD). The structural evolution of the deposited films annealed at various temperatures (Ta) is investigated. Experimental results indicate that the crystallization occurs to form Ge and Si clusters as Ta = 500 °C. With raising Ta up to 900 °C, Ge clusters percolate together and Si diffuses and redistributes to form a Ge/SiGe core/shell structure, and some Ge atoms partially diffuse to the surface as a result of segregation. The present work will be helpful in understanding the structural evolution process of a hybrid SiGe films and beneficial for further optimizing the microstructure and properties.

  12. Novel multiple criteria decision making methods based on bipolar neutrosophic sets and bipolar neutrosophic graphs

    OpenAIRE

    Muhammad, Akram; Musavarah, Sarwar

    2016-01-01

    In this research study, we introduce the concept of bipolar neutrosophic graphs. We present the dominating and independent sets of bipolar neutrosophic graphs. We describe novel multiple criteria decision making methods based on bipolar neutrosophic sets and bipolar neutrosophic graphs. We also develop an algorithm for computing domination in bipolar neutrosophic graphs.  

  13. Bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A.

    2008-10-21

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  14. Electrical Performance of Electron Irradiated SiGe HBT and Si BJT

    Institute of Scientific and Technical Information of China (English)

    Wentao HUANG; Jilin WANG; Zhinong LIU; Peiyi CHEN; Peihsin TSIEN; Xiangti MENG

    2004-01-01

    The change of electrical performances of 1 MeV electron irradiated silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) and Si bipolar junction transistor (BJT) was studied. After electron irradiation, both the collector current IC and the base current IB changed a little, and the current gainβ decreased a little for SiGe HBT. The higher the electron irradiation fluence was, the lower the IC decreased. For conventional Si BJT, IC and IB increased as well asβ decreased much larger than SiGe HBT under the same fluence. The contribution of IB was more important to the degradation ofβ for both SiGeHBT and Si BJT. It was shown that SiGe HBT had a larger anti-radiation threshold and better anti-radiation performance than Si BJT. The mechanism of electrical performance changes induced by irradiation was preliminarily discussed.

  15. Asenapine for bipolar disorder

    Directory of Open Access Journals (Sweden)

    Scheidemantel T

    2015-12-01

    Full Text Available Thomas Scheidemantel,1 Irina Korobkova,2 Soham Rej,3,4 Martha Sajatovic1,2 1University Hospitals Case Medical Center, 2Case Western Reserve University School of Medicine, Cleveland, OH, USA; 3Department of Psychiatry, University of Toronto, Toronto, ON, 4Geri PARTy Research Group, Jewish General Hospital, Montreal, QC, Canada Abstract: Asenapine (Saphris® is an atypical antipsychotic drug which has been approved by the US Food and Drug Administration for the treatment of schizophrenia in adults, as well as the treatment of acute manic or mixed episodes of bipolar I in both adult and pediatric populations. Asenapine is a tetracyclic drug with antidopaminergic and antiserotonergic activity with a unique sublingual route of administration. In this review, we examine and summarize the available literature on the safety, efficacy, and tolerability of asenapine in the treatment of bipolar disorder (BD. Data from randomized, double-blind trials comparing asenapine to placebo or olanzapine in the treatment of acute manic or mixed episodes showed asenapine to be an effective monotherapy treatment in clinical settings; asenapine outperformed placebo and showed noninferior performance to olanzapine based on improvement in the Young Mania Rating Scale scores. There are limited data available on the use of asenapine in the treatment of depressive symptoms of BD, or in the maintenance phase of BD. The available data are inconclusive, suggesting the need for more robust data from prospective trials in these clinical domains. The most commonly reported adverse effect associated with use of asenapine is somnolence. However, the somnolence associated with asenapine use did not cause significant rates of discontinuation. While asenapine was associated with weight gain when compared to placebo, it appeared to be modest when compared to other atypical antipsychotics, and its propensity to cause increases in hemoglobin A1c or serum lipid levels appeared to be

  16. Risk factors for suicide among children and youths with bipolar spectrum and early bipolar disorder.

    Directory of Open Access Journals (Sweden)

    Aleksandra Rajewska-Rager

    2015-06-01

    the overview of recent years literature available in PubMed/MEDLINE database, including the following search criteria: early onset bipolar disorder, bipolar disorder in children and young people, the spectrum of bipolar disorder, and suicidal ideation, suicidal intent, suicide.

  17. Electric and Magnetic Field Tunable Rectification and Magnetoresistance in FexGe1-x/Ge Heterojunction Diodes

    Institute of Scientific and Technical Information of China (English)

    QIN Yu-Feng; CHEN Yan-Xue; MEI Liang-Mo; ZHANG Ze; YAN Shi-Shen; KANG Shi-Shou; XIAO Shu-Qin; LI Qiang; DAI Zheng-Kun; SHEN Ting-Ting; DAI You-Yong; LIU Guo-Lei

    2011-01-01

    Fex Ge1- x/Ge amorphous heterojunction diodes with p-Fex Ge1-x ferromagnetic semiconductor layers are grown on single-crystal Ge substrates of p-type,n-type and intrinsic semiconductors,respectively.The I-V curves of pFe0.4 Ge0.6 /p-Ge diodes only show slight changes with temperature or with magnetic field.For the p-Fe0.4 Ge0.6 /nGe diode,good rectification is maintained at room temperature.More interestingly,the I-V curve of the pFe0.4Ge0.6/i-Ge diode can be tuned by the magnetic field,indicating a large positive magnetoresistance.The resistances of the junctions decrease with the increasing temperature,suggesting a typical semiconductor transport behavior.The origin of the positive magnetoresistance is discussed based on the effect of the electric and magnetic field on the energy band structures of the interface.In the past decades,ferromagnetic semiconductors (FMSs),which can be used as spin current sources,have received much attention due to their potential application in the next generation of information technology.In 1996,Ohno et a/.… reported molecular beam epitaxial (Ga,Mn)As FMSs,which show a wellaligned ferromagnetic order and an anomalous Halleffect.In 2002,Park et al.[2]%FexGe1-x/Ge amorphous heterojunction diodes with p-FexGe1-x ferromagnetic semiconductor layers are grown on single-crystal Ge substrates of p-type, n-type and intrinsic semiconductors, respectively. The I-V curves of p-Fe0.4Geo.6/p-Ge diodes only show slight changes with temperature or with magnetic field. For the p-Fe0.4Ge0.6/n-Ge diode, good rectification is maintained at room temperature. More interestingly, the I-V curve of the p-Fe0.4Ge0.6/I-Ge diode can be tuned by the magnetic field, indicating a large positive magnetoresistance. The resistances of the junctions decrease with the increasing temperature, suggesting a typical semiconductor transport behavior. The origin of the positive magnetoresistance is discussed based on the effect of the electric and magnetic field on the

  18. Pseudomorphic GeSn/Ge (001) heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tonkikh, A. A., E-mail: tonkikh@mpi-halle.de [Max Planck Institute of Microstructure Physics (Germany); Talalaev, V. G. [Martin Luther University Halle-Wittenberg, ZIK SiLi-nano (Germany); Werner, P. [Max Planck Institute of Microstructure Physics (Germany)

    2013-11-15

    The synthesis of pseudomorphic GeSn heterostructures on a Ge (001) substrate by molecular-beam epitaxy is described. Investigations by transmission electron microscopy show that the GeSn layers are defect free and possess cubic diamondlike structure. Photoluminescence spectroscopy reveals interband radiative recombination in the GeSn quantum wells, which is identified as indirect transitions between the subbands of heavy electrons and heavy holes. On the basis of experimental data and modeling of the band structure of pseudomorphic GeSn compounds, the lower boundary of the bowing parameter for the indirect band gap is estimated as b{sub L} {>=} 1.47 eV.

  19. Infrared transient grating measurements of the dynamics of hydrogen local mode vibrations in amorphous silicon-germanium

    NARCIS (Netherlands)

    Jobson, K. W.; Wells, J. P. R.; Schropp, R. E. I.; Vinh, N. Q.; Dijkhuis, J. I.

    2008-01-01

    We report on picosecond, time-resolved measurements of the vibrational relaxation and decay pathways of the Si-H and Ge-H stretching modes in hydrogenated amorphous silicon-germanium thin films (a-SiGe: H). It is demonstrated that the decay of both modes has a nonexponential shape, attributable to t

  20. 193 nm Excimer laser processing of Si/Ge/Si(100) micropatterns

    Science.gov (United States)

    Gontad, F.; Conde, J. C.; Chiussi, S.; Serra, C.; González, P.

    2016-01-01

    193 nm Excimer laser assisted growth and crystallization of amorphous Si/Ge bilayer patterns with circular structures of 3 μm diameter and around 25 nm total thickness, is presented. Amorphous patterns were grown by Laser induced Chemical Vapor Deposition, using nanostencils as shadow masks and then irradiated with the same laser to induce structural and compositional modifications for producing crystalline SiGe alloys through fast melting/solidification cycles. Compositional and structural analyses demonstrated that pulses of 240 mJ/cm2 lead to graded SiGe alloys with Si rich discs of 2 μm diameter on top, a buried Ge layer, and Ge rich SiGe rings surrounding each feature, as predicted by previous numerical simulation.

  1. Quetiapine monotherapy for bipolar depression

    Directory of Open Access Journals (Sweden)

    Michael E Thase

    2008-03-01

    Full Text Available Michael E ThaseDepartments of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, PA, USA; the Philadelphia Veterans Affairs Medical Center, Philadelphia, PA, USA; and the University of Pittsburgh Medical Center, Pittsburgh, PA, USAAbstract: Bipolar depression is more common, disabling, and difficult-to-treat than the manic and hypomanic phases that define bipolar disorder. Unlike the treatment of so-called “unipolar” depressions, antidepressants generally are not indicated as monotherapies for bipolar depressions and recent studies suggest that - even when used in combination with traditional mood stabilizers – antidepressants may have questionable value for bipolar depression. The current practice is that mood stabilizers are initiated first as monotherapies; however, the antidepressant efficacy of lithium and valproate is modest at best. Within this context the role of atypical antipsychotics is being evaluated. The combination of olanzapine and the antidepressant fluoxetine was the first treatment to receive regulatory approval in the US specifically for bipolar I depression. Quetiapine was the second medication to be approved for this indication, largely as the result of two pivotal trials known by the acronyms of BOLDER (BipOLar DEpRession I and II. Both studies demonstrated that two doses of quetiapine (300 mg and 600 mg given once daily at bedtime were significantly more effective than placebo, with no increased risk of patients switching into mania. Pooling the two studies, quetiapine was effective for both bipolar I and bipolar II depressions and for patients with (and without a history of rapid cycling. The two doses were comparably effective in both studies. Although the efficacy of quetiapine monotherapy has been established, much additional research is necessary. Further studies are needed to more fully investigate dose-response relationships and comparing quetiapine monotherapy to other mood stabilizers

  2. [Unipolar versus bipolar depression: clues toward predicting bipolarity disorder].

    Science.gov (United States)

    Ben Abla, T; Ellouze, F; Amri, H; Krid, G; Zouari, A; M'Rad, M F

    2006-01-01

    Bipolar and unipolar disorders share a common depressive clinical manifestation. It is important to distinguish between these two forms of depression for several reasons. First, prescribing antidepressors in monotherapy indubitably worsens the prognosis of bipolarity disorders. Second, postponing the prescription of a mood stabilizer reduces the efficacy of the treatment and multiplies the suicidal risks by two. The object of this study is to reveal the factors that distinguish between unipolar and bipolar depression. This is a retrospective study on patients' files. It includes 186 patients divided according to DSM IV criteria into two groups: patients with bipolar disorder type I or II with a recent depressive episode (123 patients) and patients with recurrent depressive disorder (63 patients). A medical record card was filled-in for every patient. It included socio-demographic data, information about the disorder, family antecedents, CGI score (global clinical impressions), physical comorbidity, substance abuse and personality disorder. In order to sort out the categorization variables, the two groups were compared using chi2 test or Fischer's test. With regard to the quantitative variables, the two groups were compared using Krostal Wallis's test or Ancova. Our study has revealed that bipolar disorder differs significantly from unipolar disorder in the following respects: bipolar disorder is prevalent among men (sex-ratio 2) while unipolar disorder is prevailing among women (sex-ratio 0.8); patients with bipolar disorder are younger than patients with unipolar disorder (38.1 +/- 5 years vs. 49.7 +/- years); the age at the onset of bipolar disorder is earlier than that of unipolar disorder (20.8 +/- 2 years vs. 38.7 +/- 5 years); family antecedents are more important in bipolar patients than in unipolar patients (51.1% vs. 33%). More importantly, bipolar disorder differs from unipolar disorder in the following aspects: The number of suicidal attempts (25.3% vs

  3. Phase-Change Memory Properties of Electrodeposited Ge-Sb-Te Thin Film

    OpenAIRE

    Huang, Ruomeng; Kissling, Gabriela; Jolleys, Andrew; Bartlett, Philip; Hector, Andrew; Levason, William; Reid, Gillian; De Groot, Cornelis

    2015-01-01

    We report the properties of a series of electrodeposited Ge-Sb-Te alloys with various compositions. It is shown that the Sb/Ge ratio can be varied in a controlled way by changing the electrodeposition potential. This method opens up the prospect of depositing Ge-Sb-Te super-lattice structures by electrodeposition. Material and electrical characteristics of various compositions have been investigated in detail, showing up to three orders of magnitude resistance ratio between the amorphous and ...

  4. Integrated neurobiology of bipolar disorder

    Directory of Open Access Journals (Sweden)

    Vladimir eMaletic

    2014-08-01

    Full Text Available From a neurobiological perspective there is no such thing as bipolar disorder. Rather, it is almost certainly the case that many somewhat similar, but subtly different, pathological conditions produce a disease state that we currently diagnose as bipolarity. This heterogeneity—reflected in the lack of synergy between our current diagnostic schema and our rapidly advancing scientific understanding of the condition—limits attempts to articulate an integrated perspective on bipolar disorder. However, despite these challenges, scientific findings in recent years are beginning to offer a provisional unified field theory of the disease. This theory sees bipolar disorder as a suite of related neurodevelopmental conditions with interconnected functional abnormalities that often appear early in life and worsen over time. In addition to accelerated loss of volume in brain areas known to be essential for mood regulation and cognitive function, consistent findings have emerged at a cellular level, providing evidence that bipolar disorder is reliably associated with dysregulation of glial-neuronal interactions. Among these glial elements are microglia—the brain’s primary immune elements, which appear to be overactive in the context of bipolarity. Multiple studies now indicate that inflammation is also increased in the periphery of the body in both the depressive and manic phases of the illness, with at least some return to normality in the euthymic state. These findings are consistent with changes in the HPA axis, which are known to drive inflammatory activation. In summary, the very fact that no single gene, pathway or brain abnormality is likely to ever account for the condition is itself an extremely important first step in better articulating an integrated perspective on both its ontological status and pathogenesis. Whether this perspective will translate into the discovery of innumerable more homogeneous forms of bipolarity is one of the great

  5. Creativity in familial bipolar disorder.

    Science.gov (United States)

    Simeonova, Diana I; Chang, Kiki D; Strong, Connie; Ketter, Terence A

    2005-11-01

    Studies have demonstrated relationships between creativity and bipolar disorder (BD) in individuals, and suggested familial transmission of both creativity and BD. However, to date, there have been no studies specifically examining creativity in offspring of bipolar parents and clarifying mechanisms of intergenerational transmission of creativity. We compared creativity in bipolar parents and their offspring with BD and bipolar offspring with attention-deficit/hyperactivity disorder (ADHD) with healthy control adults and their children. 40 adults with BD, 20 bipolar offspring with BD, 20 bipolar offspring with ADHD, and 18 healthy control parents and their healthy control children completed the Barron-Welsh Art Scale (BWAS), an objective measure of creativity. Adults with BD compared to controls scored significantly (120%) higher on the BWAS Dislike subscale, and non-significantly (32%) higher on the BWAS Total scale. Mean BWAS Dislike subscale scores were also significantly higher in offspring with BD (107% higher) and offspring with ADHD (91% higher) than in healthy control children. Compared to healthy control children, offspring with BD had 67% higher and offspring with ADHD had 40% higher BWAS Total scores, but these differences failed to reach statistical significance when adjusted for age. In the bipolar offspring with BD, BWAS Total scores were negatively correlated with duration of illness. The results of this study support an association between BD and creativity and contribute to a better understanding of possible mechanisms of transmission of creativity in families with genetic susceptibility for BD. This is the first study to show that children with and at high risk for BD have higher creativity than healthy control children. The finding in children and in adults was related to an enhanced ability to experience and express dislike of simple and symmetric images. This could reflect increased access to negative affect, which could yield both benefits

  6. Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2014-01-01

    Full Text Available Ge nanocrystals (Ge-ncs embedded in a SiO2 superlattice structure were prepared by magnetron cosputtering and postdeposition annealing. The formation of spherical nanocrystals was confirmed by transmission electron microscopy and their growth process was studied by a combination of spectroscopic techniques. The crystallinity volume fraction of Ge component was found to increase with crystallite size, but its overall low values indicated a coexistence of crystalline and noncrystalline phases. A reduction of Ge-O species was observed in the superlattice during thermal annealing, accompanied by a transition from oxygen-deficient silicon oxide to silicon dioxide. A growth mechanism involving phase separation of Ge suboxides (GeOx was then proposed to explain these findings and supplement the existing growth models for Ge-ncs in SiO2 films. Further analysis of the bonding structure of Ge atoms suggested that Ge-ncs are likely to have a core-shell structure with an amorphous-like surface layer, which is composed of GeSiO ternary complex. The surface layer thickness was extracted to be a few angstroms and equivalent to several atomic layer thicknesses.

  7. Te-centric view of the phase change mechanism in Ge-Sb-Te alloys.

    Science.gov (United States)

    Sen, S; Edwards, T G; Cho, J-Y; Joo, Y-C

    2012-05-11

    The short-range structure of amorphous and fcc Ge1Sb2Te4 and Ge2Sb2Te5 phase-change alloys is investigated using 125Te NMR spectroscopy. Both amorphous and fcc structures consist solely of heteropolar Ge/Sb-Te bonds that may enable rapid displacive phase transformation without the need for extensive atomic rearrangement. The vacancy distribution is random in microcrystalline fcc phases while significant clustering is observed in their nanocrystalline counterparts that may result in the formation of tetrahedrally coordinated Ge atoms in the latter. This structural commonality may further facilitate the kinetics of transformation between amorphous and nanocrystalline fcc phases, a situation relevant for high-density memory storage.

  8. Plasmon-assisted photoresponse in Ge-coated bowtie nanojunctions

    CERN Document Server

    Evans, Kenneth M; Natelson, Douglas

    2016-01-01

    We demonstrate plasmon-enhanced photoconduction in Au bowtie nanojunctions containing nanogaps overlaid with an amorphous Ge film. The role of plasmons in the production of nanogap photocurrent is verified by studying the unusual polarization dependence of the photoresponse. With increasing Ge thickness, the nanogap polarization of the photoresponse rotates 90 degrees, indicating a change in the dominant relevant plasmon mode, from the resonant transverse plasmon at low thicknesses to the nonresonant "lightning rod" mode at higher thicknesses. To understand the plasmon response in the presence of the Ge overlayer and whether the Ge degrades the Au plasmonic properties, we investigate the photothermal response (from the temperature-dependent Au resistivity) in no-gap nanowire structures, as a function of Ge film thickness and nanowire geometry. The film thickness and geometry dependence are modeled using a cross-sectional, finite element simulation. The no-gap structures and the modeling confirm that the strik...

  9. Brainstorm: occupational choice, bipolar illness and creativity.

    Science.gov (United States)

    Tremblay, Carol Horton; Grosskopf, Shawna; Yang, Ke

    2010-07-01

    Although economists have analyzed earnings, unemployment, and labor force participation for those with bipolar illness, occupational choice has yet to be explored. Psychological and medical studies often suggest an association between bipolar illness and creative achievement, but they tend to focus on eminent figures, case studies, or small samples. We seek to examine occupational creativity of non-eminent individuals with bipolar disorder. We use Epidemiologic Catchment Area data to estimate a multinomial logit model matched to an index of occupational creativity. Those with bipolar illness appear to be disproportionately concentrated in the most creative occupational category. Nonparametric kernel density estimates reveal that the densities of the occupational creativity variable for the bipolar and non-bipolar individuals significantly differ in the ECA data, and suggest that the probability of engaging in creative activities on the job is higher for bipolar than non-bipolar workers.

  10. Imunologia do transtorno bipolar Immunology of bipolar disorder

    Directory of Open Access Journals (Sweden)

    Izabela Guimarães Barbosa

    2009-01-01

    Full Text Available OBJETIVO: Pesquisas recentes têm implicado fatores imunes na patogênese de diversos transtornos neuropsiquiátricos. O objetivo do presente trabalho é revisar os trabalhos que investigaram a associação entre transtorno bipolar e alterações em parâmetros imunes. MÉTODOS: Artigos que incluíam as palavras-chave: "bipolar disorder", "mania", "immunology", "cytokines", "chemokines", "interleukins", "interferon" e "tumor necrosis factor" foram selecionados em uma revisão sistemática da literatura. As bases de dados avaliadas foram MedLine e Scopus, entre os anos de 1980 e 2008. RESULTADOS: Foram identificados 28 trabalhos que estudaram alterações imunes em pacientes com transtorno bipolar. Seis artigos investigaram genes relacionados à resposta imune; cinco, autoanticorpos; quatro, populações leucocitárias; 13, citocinas e/ou moléculas relacionadas à resposta imune e seis, leucócitos de pacientes in vitro. CONCLUSÕES: Embora haja evidências na literatura correlacionando o transtorno bipolar a alterações imunes, os dados não são conclusivos. O transtorno bipolar parece estar associado a níveis mais elevados de autoanticorpos circulantes, assim como à tendência à ativação imune com produção de citocinas pró-inflamatórias e redução de parâmetros anti-inflamatórios.OBJECTIVE: Emerging research has implicated immune factors in the pathogenesis of a variety of neuropsychiatric disorders. The objective of the present paper is to review the studies that investigated the association between bipolar disorder and immune parameters. METHODS: Papers that included the keywords "bipolar to disorder", "mania", "immunology", "cytokines", "chemokines", "interleukins", "interferon" and "tumor necrosis factor" were selected in a systematic review of the literature. The evaluated databases were MedLine and Scopus in the period between 1980 and 2008. RESULTS: Twenty eight works were found. Six studies investigated immune response

  11. Properties of amorphous carbon

    CERN Document Server

    2003-01-01

    Amorphous carbon has a wide range of properties that are primarily controlled by the different bond hydridisations possible in such materials. This allows for the growth of an extensive range of thin films that can be tailored for specific applications. Films can range from those with high transparency and are hard diamond-like, through to those which are opaque, soft and graphitic-like. Films with a high degree of sp3 bonding giving the diamond-like properties are used widely by industry for hard coatings. Application areas including field emission cathodes, MEMS, electronic devices, medical and optical coatings are now close to market. Experts in amorphous carbon have been drawn together to produce this comprehensive commentary on the current state and future prospects of this highly functional material.

  12. Magnetostrictive amorphous bimetal sensors

    CERN Document Server

    Mehnen, L; Kaniusas, E

    2000-01-01

    The paper describes the application of a magnetostrictive amorphous ribbon (AR) for the detection of bending. In order to increase sensitivity, a bimetal structure is used which consists of AR and a nonmagnetic carrier ribbon. Several methods for the preparation of the bimetal are discussed. Results of the bending sensitivities are given for various combinations of the material types indicating crucial problems of bimetal preparation.

  13. Bipolar illness, creativity, and treatment.

    Science.gov (United States)

    Rothenberg, A

    2001-01-01

    There have been in recent years increasing claims in both popular and professional literature for a connection between bipolar illness and creativity. A review of studies supporting this claim reveals serious flaws in sampling, methodology, presentation of results, and conclusions. Although there is therefore no evidence for etiological or genetic linkages, it is still necessary to explain interrelationships in those creative persons suffering from the illness. Examples of the work in progress of artists with bipolar disorder, Jackson Pollock and Edvard Munch, illustrate the use of healthy and adaptive creative cognition--janusian and homospatial processes--in the former's breakthrough conception during an improvement phase in treatment leading to the development of the Abstract Expressionist Movement and in the latter's transformation of an hallucination into his famous artwork "The Scream." Treatment options that do not produce cognitive effects are important for creative persons with bipolar disorder.

  14. Comprehensive modeling of ion-implant amorphization in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mok, K.R.C. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain) and Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576 (Singapore)]. E-mail: g0202446@nus.edu.sg; Jaraiz, M. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Martin-Bragado, I. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Synopsys, Karl-Hammerschmidt Strasse 34, D-85609 Aschheim/Dornach (Germany); Rubio, J.E. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Castrillo, P. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Pinacho, R. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Srinivasan, M.P. [Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576 (Singapore); Benistant, F. [Chartered Semiconductor Manufacturing. 60 Woodlands Industrial Park D, Street 2, Singapore 738406 (Singapore)

    2005-12-05

    A physically based model has been developed to simulate the ion-implant induced damage accumulation up to amorphization in silicon. Based on damage structures known as amorphous pockets (AP), which are three-dimensional, irregularly shaped agglomerates of interstitials (I) and vacancies (V) surrounded by crystalline silicon, the model is able to reproduce a wide range of experimental observations of damage accumulation and amorphization with interdependent implantation parameters. Instead of recrystallizing the I's and V's instantaneously, the recrystallization rate of an AP containing nI and mV is a function of its effective size, defined as min(n, m), irrespective of its internal spatial configuration. The parameters used in the model were calibrated using the experimental silicon amorphous-crystalline transition temperature as a function of dose rate for C, Si, and Ge. The model is able to show the superlinear damage build-up with dose, the extent of amorphous layer and the superadditivity effect of polyatomic ions.

  15. Fabrication and ferromagnetism of Si-SiGe/MnGe core-shell nanopillars

    Science.gov (United States)

    Wang, Liming; Liu, Tao; Wang, Shuguang; Zhong, Zhenyang; Jia, Quanjie; Jiang, Zuimin

    2016-10-01

    Si-Si0.5Ge0.5/Mn0.08Ge0.92 core-shell nanopillar samples were fabricated on ordered Si nanopillar patterned substrates by molecular beam epitaxy at low temperatures. The magnetic properties of the samples are found to depend heavily on the growth temperature of the MnGe layer. The sample grown at a moderate temperature of 300 °C has the highest Curie temperature of 240 K as well as the strongest ferromagnetic signals. On the basis of the microstructural results, the ferromagnetic properties of the samples are believed to come from the intrinsic Mn-doped amorphous or crystalline Ge ferromagnetic phase rather than any intermetallic ferromagnetic compounds of Mn and Ge. After being annealed at a temperature of 500 °C, all the samples exhibit the same Curie temperature of 220 K, which is in sharp contrast to the different Curie temperature for the as-grown samples, and the ferromagnetism for the annealed samples comes from Mn5GeSi2 compounds which are formed during the annealing.

  16. Experimental DC extraction of the thermal resistance of bipolar transistors taking into account the Early effect

    Science.gov (United States)

    d'Alessandro, Vincenzo

    2017-01-01

    This paper presents three methods to experimentally extract the thermal resistance of bipolar transistors taking into account the Early effect. The approaches are improved variants of recently-proposed techniques relying on common-base DC measurements. The accuracy is numerically verified by making use of a compact model calibrated on I-V characteristics of state-of-the-art SOG BJTs and SiGe:C HBTs.

  17. Corrosion resistant metallic bipolar plate

    Science.gov (United States)

    Brady, Michael P.; Schneibel, Joachim H.; Pint, Bruce A.; Maziasz, Philip J.

    2007-05-01

    A corrosion resistant, electrically conductive component such as a bipolar plate for a PEM fuel cell includes 20 55% Cr, balance base metal such as Ni, Fe, or Co, the component having thereon a substantially external, continuous layer of chromium nitride.

  18. Effect of selenium addition on the GeTe phase change memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Vinod, E.M., E-mail: vinuem@gmail.com [Department of Physics, Indian Institute of Science, Bangalore 560 012 (India); Singh, A.K.; Ganesan, R. [Department of Physics, Indian Institute of Science, Bangalore 560 012 (India); Sangunni, K.S., E-mail: sangu@physics.iisc.ernet.in [Department of Physics, Indian Institute of Science, Bangalore 560 012 (India)

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer Selenium is used as an additive to GeTe phase change materials. Black-Right-Pointing-Pointer Crystalline structure of GeTe alloys does not affect up to 0.20 at.% of Se. Black-Right-Pointing-Pointer The possibility of Se occupying Ge vacancy sites in GeTe structure is explained. Black-Right-Pointing-Pointer Ge-Se and GeTe{sub 2} bonds increase with increase of Se concentration. Black-Right-Pointing-Pointer T{sub m} is reduced in 0.50 at.% Se alloy, which can reduce RESET current requirements. - Abstract: Compositional dependent investigations of the bulk GeTe chalcogenides alloys added with different selenium concentrations are carried out by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), electron probe micro-analyzer (EPMA) and differential scanning calorimetry (DSC). The measurements reveal that GeTe crystals are predominant in alloys up to 0.20 at.% of Se content indicating interstitial occupancy of Se in the Ge vacancies. Raman modes in the GeTe alloys changes to GeSe modes with the addition of Se. Amorphousness in the alloy increases with increase of Se and 0.50 at.% Se alloy forms a homogeneous amorphous phase with a mixture of Ge-Se and Te-Se bonds. Structural changes are explained with the help of bond theory of solids. Crystallization temperature is found to be increasing with increase of Se, which will enable the amorphous stability. For the optimum 0.50 at.% Se alloy, the melting temperature has reduced which will reduce the RESET current requirement for the phase change memory applications.

  19. Formation of GeSn alloy on Si(100) by low-temperature molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Talochkin, A. B., E-mail: tal@isp.nsc.ru [A. V. Rzhanov Institute of Semiconductor Physics, Lavrentyev Avenue 13, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Mashanov, V. I. [A. V. Rzhanov Institute of Semiconductor Physics, Lavrentyev Avenue 13, Novosibirsk 630090 (Russian Federation)

    2014-12-29

    GeSn alloys grown on Si(100) by the low-temperature (100 °C) molecular beam epitaxy are studied using scanning tunneling microscopy and Raman spectroscopy. It is found that the effect of Sn as a surfactant modifies substantially the low-temperature growth mechanism of Ge on Si. Instead of the formation of small Ge islands surrounded by amorphous Ge, in the presence of Sn, the growth of pure Ge islands appears via the Stranski-Krastanov growth mode, and a partially relaxed Ge{sub 1−x}Sn{sub x} alloy layer with the high Sn-fraction up to 40 at. % is formed in the area between them. It is shown that the observed growth mode induced by high surface mobility of Sn and the large strain of the pseudomorphic state of Ge to Si ensures the minimum elastic-strain energy of the structure.

  20. Bipolar Neutrosophic Refined Sets and Their Applications in Medical Diagnosis

    OpenAIRE

    Deli, Irfan; Yusuf, Şubaş

    2016-01-01

    This paper proposes concept of bipolar neutrosophic refined set and its some operations. Firstly, a score certainty and accuracy function to compare the bipolar neutrosophic refined information is defined. Secondly, to aggregate the bipolar neutrosophic refined information, a bipolar neutrosophic refined weighted average operator and a bipolar neutrosophic refined weighted geometric operator is developed.

  1. Responsabilidade penal no transtorno bipolar Penal responsibility in bipolar disorder

    Directory of Open Access Journals (Sweden)

    Alexandre Martins Valença

    2010-01-01

    Full Text Available Os autores relatam o caso de uma mulher que cometeu delito de assalto e foi avaliada em perícia psiquiátrica para análise da responsabilidade penal. Conclui-se que ela apresentava doença mental, na forma de transtorno bipolar, daí ser inimputável. A avaliação da responsabilidade penal é de extrema importância, para que se possam aplicar medidas de segurança ou sanções penais e correcionais adequadas a cada caso.The authors report a case of a woman who committed the crime of assault and was evaluated in penal imputability exam to assess criminal responsibility. It was concluded that she had a mental illness, bipolar disorder, being inimputable. The evaluation of penal responsibility is extremely important, in order to apply adequate involuntary commitment or correctional and penal sanctions to each case.

  2. Laser ablation and growth of Si and Ge

    Energy Technology Data Exchange (ETDEWEB)

    Yap, Seong Shan, E-mail: seong.yap@ntnu.no [Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Siew, Wee Ong; Nee, Chen Hon [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Reenaas, Turid Worren [Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Tou, Teck Yong [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia)

    2012-02-01

    In this work, we investigated the laser ablation and deposition of Si and Ge at room temperature in vacuum by employing nanosecond lasers of 248 nm, 355 nm, 532 nm and 1064 nm. Time-integrated optical emission spectra were obtained for neutrals and ionized Ge and Si species in the plasma at laser fluences from 0.5 to 11 J/cm{sup 2}. The deposited films were characterized by using Raman spectroscopy, scanning electron microscopy and atomic force microscopy. Amorphous Si and Ge films, micron-sized crystalline droplets and nano-sized particles were deposited. The results suggested that ionized species in the plasma promote the process of subsurface implantation for both Si and Ge films while large droplets were produced from the superheated and melted layer of the target. The dependence of the properties of the materials on laser wavelength and fluence were discussed.

  3. Formation of Ge{sup 0} and GeO{sub x} nanoclusters in Ge{sup +}-implanted SiO{sub 2}/Si thin-film heterostructures under rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, A.F., E-mail: a.f.zatsepin@urfu.ru [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Zatsepin, D.A. [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Institute of Metal Physics, Russian Academy of Sciences – Ural Division, S. Kovalevskoi Str. 18, 620990 Yekaterinburg (Russian Federation); Institute of Physics, Polish Academy of Science, 02-668 Warsaw (Poland); Zhidkov, I.S. [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Kurmaev, E.Z. [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Institute of Metal Physics, Russian Academy of Sciences – Ural Division, S. Kovalevskoi Str. 18, 620990 Yekaterinburg (Russian Federation); Fitting, H.-J. [Institute of Physics, University of Rostock, D-18051 Rostock (Germany); Schmidt, B. [Institute of Ion Beam Physics, Research Center Dresden-Rossendorf, POB 510119, 01314 Dresden (Germany); Mikhailovich, A.P. [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Lawniczak-Jablonska, K. [Institute of Physics, Polish Academy of Science, 02-668 Warsaw (Poland)

    2015-09-15

    Highlights: • Results of XPS for valence and core levels of Ge implanted SiO{sub 2} films are presented. • Chemical-state transformation of the host-matrix composition and Ge ions is performed. • The rapid thermal annealing strongly affects the oxidation states of Ge-atoms. • The formation of Ge{sup 0} and GeO{sub x} clusters within subsurface layer is observed. - Abstract: The results of X-ray photoelectron spectra (XPS valence band and core levels) measurements for Ge{sup +} implanted SiO{sub 2}/Si heterostructures are presented. These heterostructures have a 30 nm thick Ge{sup +} ion implanted amorphous SiO{sub 2} layer on p-type Si. The chemical-state transformation of the host-matrix composition after Ge{sup +} ion implantation and rapid thermal annealing (RTA) are discussed. The XPS-analysis performed allows to conclude the formation of Ge{sup 0} and GeO{sub x} clusters within the samples under study. It was established, that the annealing time strongly affects the degree of oxidation states of Ge-atoms.

  4. Morphological analysis of GeTe in inline phase change switches

    Science.gov (United States)

    King, Matthew R.; El-Hinnawy, Nabil; Salmon, Mike; Gu, Jitty; Wagner, Brian P.; Jones, Evan B.; Borodulin, Pavel; Howell, Robert S.; Nichols, Doyle T.; Young, Robert M.

    2015-09-01

    Crystallization and amorphization phenomena in indirectly heated phase change material-based devices were investigated. Scanning transmission electron microscopy was utilized to explore GeTe phase transition processes in the context of the unique inline phase change switch (IPCS) architecture. A monolithically integrated thin film heating element successfully converted GeTe to ON and OFF states. Device cycling prompted the formation of an active area which sustains the majority of structural changes during pulsing. A transition region on both sides of the active area consisting of polycrystalline GeTe and small nuclei (<15 nm) in an amorphous matrix was also observed. The switching mechanism, determined by variations in pulsing parameters, was shown to be predominantly growth-driven. A preliminary model for crystallization and amorphization in IPCS devices is presented.

  5. Role of Ge Switch in Phase Transition: Approach using Atomically Controlled GeTe/Sb2Te3 Superlattice

    Science.gov (United States)

    Tominaga, Juniji; Fons, Paul; Kolobov, Alexander; Shima, Takayuki; Chong, Tow Chong; Zhao, Rong; Koon Lee, Hock; Shi, Luping

    2008-07-01

    Germanium-antimony-tellurite (GST) is a very attractive material not only for rewritable optical media but also for realizing solid state devices. Recently, the study of the switching mechanism between the amorphous and crystal states has actively been carried out experimentally and theoretically. Now, the role of the flip-flop transition of a Ge atom in a distorted simple-cubic unit cell is the center of discussion. Turning our viewpoint towards a much wider region beyond a unit cell, we can understand that GeSbTe consists of two units: one is a Sb2Te3 layer and the other is a Ge2Te2 layer. On the based of this simple model, we fabricated the superlattice of GST alloys and estimated their thermal properties by differential scanning calorimetry (DSC). In this paper, we discuss the proof of the Ge switch on the basis of thermo-histories.

  6. The International Society for Bipolar Disorders (ISBD) Task Force Report on Antidepressant Use in Bipolar Disorders

    NARCIS (Netherlands)

    Pacchiarotti, Isabella; Bond, David J.; Baldessarini, Ross J.; Nolen, Willem A.; Grunze, Heinz; Licht, Rasmus W.; Post, Robert M.; Berk, Michael; Goodwin, Guy M.; Sachs, Gary S.; Tondo, Leonardo; Findling, Robert L.; Youngstrom, Eric A.; Tohen, Mauricio; Undurraga, Juan; Gonzalez-Pinto, Ana; Goldberg, Joseph F.; Yildiz, Aysegul; Altshuler, Lori L.; Calabrese, Joseph R.; Mitchell, Philip B.; Thase, Michael E.; Koukopoulos, Athanasios; Colom, Francesc; Frye, Mark A.; Malhi, Gin S.; Fountoulakis, Konstantinos N.; Vazquez, Gustavo; Perlis, Roy H.; Ketter, Terence A.; Cassidy, Frederick; Akiskal, Hagop; Azorin, Jean-Michel; Valenti, Marc; Mazzei, Diego Hidalgo; Lafer, Beny; Kato, Tadafumi; Mazzarini, Lorenzo; Martinez-Aran, Anabel; Parker, Gordon; Souery, Daniel; Ozerdem, Aysegul; McElroy, Susan L.; Girardi, Paolo; Bauer, Michael; Yatham, Lakshmi N.; Zarate, Carlos A.; Nierenberg, Andrew A.; Birmaher, Boris; Kanba, Shigenobu; El-Mallakh, Rif S.; Serretti, Alessandro; Rihmer, Zoltan; Young, Allan H.; Kotzalidis, Georgios D.; MacQueen, Glenda M.; Bowden, Charles L.; Ghaemi, S. Nassir; Lopez-Jaramillo, Carlos; Rybakowski, Janusz; Ha, Kyooseob; Perugi, Giulio; Kasper, Siegfried; Amsterdam, Jay D.; Hirschfeld, Robert M.; Kapczinski, Flavio; Vieta, Eduard

    2013-01-01

    Objective: The risk-benefit profile of antidepressant medications in bipolar disorder is controversial. When conclusive evidence is lacking, expert consensus can guide treatment decisions. The International Society for Bipolar Disorders (ISBD) convened a task force to seek consensus recommendations

  7. Unsplit bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A.

    2011-05-24

    A bipolar pulse forming transmission line module and system for linear induction accelerators having first, second, third, and fourth planar conductors which form a sequentially arranged interleaved stack having opposing first and second ends, with dielectric layers between the conductors. The first and second planar conductors are connected to each other at the first end, and the first and fourth planar conductors are connected to each other at the second end via a shorting plate. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short at the first end a high voltage from the third planar conductor to the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  8. Beyond amorphous organic semiconductors

    Science.gov (United States)

    Hanna, Jun-ichi

    2003-07-01

    Recently it has been discovered that some types of liquid crystals, which believed to be governed by ionic conduction, exhibit a very fast electronic conduction. Their charge carrier transport is characterized by high mobility over 10-2 cm2/Vs independent of electric field and temperature. Now, the liquid crystals are being recognized as a new class of organic semiconductors. In this article, a new aspect of liquid crystals as a self-organizing molecular semiconductor are reviewed, focused on their basic charge carrier transport properties and discussed in comparison with those of molecular crystals and amorphous materials. And it is concluded that the liquid crystal is promising as a quality organic semiconductor for the devices that require a high mobility.

  9. [Major depression: features indicative of bipolarity?].

    Science.gov (United States)

    Azorin, J-M

    2011-12-01

    Several recent studies have shown that bipolar disorder is underdiagnosed in patients with major depression. Missing the diagnosis of a bipolar disorder may have serious and even occasionally fatal consequences for a patient with the disease. Moreover misdiagnosis may lead to inappropriate treatment and therefore contribute to worsening medical and functional prognosis. Although there are no pathognomonic characteristics of bipolar depression compared to unipolar depression, evidence-based findings suggest that some features may be indicative of bipolarity, in patients with depression. These features are related to clinical picture of depressive state, course of episode and illness, response to treatment, family history, comorbid conditions, as well as demographic and temperamental characteristics. Based on such features, some authors have proposed operationalized criteria or a diagnostic specific for bipolarity, to identify bipolar depression. Screening instruments may also be used, to facilitate early recognition. Validation studies of these diagnostic features and instruments are underway.

  10. Extended point defects in crystalline materials: Ge and Si.

    Science.gov (United States)

    Cowern, N E B; Simdyankin, S; Ahn, C; Bennett, N S; Goss, J P; Hartmann, J-M; Pakfar, A; Hamm, S; Valentin, J; Napolitani, E; De Salvador, D; Bruno, E; Mirabella, S

    2013-04-12

    B diffusion measurements are used to probe the basic nature of self-interstitial point defects in Ge. We find two distinct self-interstitial forms--a simple one with low entropy and a complex one with entropy ∼30  k at the migration saddle point. The latter dominates diffusion at high temperature. We propose that its structure is similar to that of an amorphous pocket--we name it a morph. Computational modeling suggests that morphs exist in both self-interstitial and vacancylike forms, and are crucial for diffusion and defect dynamics in Ge, Si, and probably many other crystalline solids.

  11. Metabolic syndrome in bipolar disorders

    Directory of Open Access Journals (Sweden)

    Sandeep Grover

    2012-01-01

    Full Text Available To review the data with respect to prevalence and risk factors of metabolic syndrome (MetS in bipolar disorder patients. Electronic searches were done in PUBMED, Google Scholar and Science direct. From 2004 to June 2011, 34 articles were found which reported on the prevalence of MetS. The sample size of these studies varied from 15 to 822 patients, and the rates of MetS vary widely from 16.7% to 67% across different studies. None of the sociodemographic variable has emerged as a consistent risk factor for MetS. Among the clinical variables longer duration of illness, bipolar disorder- I, with greater number of lifetime depressive and manic episodes, and with more severe and difficult-to-treat index affective episode, with depression at onset and during acute episodes, lower in severity of mania during the index episode, later age of onset at first manic episode, later age at first treatment for the first treatment for both phases, less healthy diet as rated by patients themselves, absence of physical activity and family history of diabetes mellitus have been reported as clinical risk factors of MetS. Data suggests that metabolic syndrome is fairly prevalent in bipolar disorder patients.

  12. Sexuality and Sexual Dysfunctions in Bipolar Disorder

    OpenAIRE

    Zeynep Namli; Gonca Karakus; Lut Tamam; Mehmet Emin Demirkol

    2016-01-01

    In the clinical course of bipolar disorder, there is a reduction in sexual will during depressive episodes and inappopriate sexual experiences and hypersexuality occurs during manic episodes. Up to now, studies focused on sexual side effects of drugs. Sexual violence, sexually transmitted diseases, contraception methods, unplanned pregnancies need to be assessed carefully in bipolar disorder patients. This review focused on sexuality and sexual dysfunctions in the course of bipolar disorder. ...

  13. Charge trapping of Ge-nanocrystals embedded in TaZrO{sub x} dielectric films

    Energy Technology Data Exchange (ETDEWEB)

    Lehninger, D., E-mail: David.Lehninger@physik.tu-freiberg.de; Seidel, P.; Geyer, M.; Schneider, F.; Heitmann, J. [Institute of Applied Physics, TU Bergakademie Freiberg, D-09596 Freiberg (Germany); Klemm, V.; Rafaja, D. [Institute of Materials Science, TU Bergakademie Freiberg, D-09596 Freiberg (Germany); Borany, J. von [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden (Germany)

    2015-01-12

    Ge-nanocrystals (NCs) were synthesized in amorphous TaZrO{sub x} by thermal annealing of co-sputtered Ge-TaZrO{sub x} layers. Formation of spherical shaped Ge-NCs with small variation of size, areal density, and depth distribution was confirmed by high-resolution transmission electron microscopy. The charge storage characteristics of the Ge-NCs were investigated by capacitance-voltage and constant-capacity measurements using metal-insulator-semiconductor structures. Samples with Ge-NCs exhibit a maximum memory window of 5 V by sweeping the bias voltage from −7 V to 7 V and back. Below this maximum, the width of the memory window can be controlled by the bias voltage. The fitted slope of the memory window versus bias voltage characteristics is very close to 1 for samples with one layer Ge-NCs. A second layer Ge-NCs does not result in a second flat stair in the memory window characteristics. Constant-capacity measurements indicate charge storage in trapping centers at the interfaces between the Ge-NCs and the surrounding materials (amorphous matrix/tunneling oxide). Charge loss occurs by thermal detrapping and subsequent band-to-band tunneling. Reference samples without Ge-NCs do not show any memory window.

  14. Quantum devices using SiGe/Si heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Karunasiri, R.P.G.; Wang, K.L. (Univ. of California, Los Angeles (United States))

    Strained-layer Si{sub 1-x}Ge{sub x}/Si heterostructures have created a great deal of interest due to the potential of integration with the conventional silicon very large scale integrated technology. With the current advances in silicon molecular beam epitaxy (Si-MBE) and other low-temperature epitaxial techniques, many Si{sub 1-x}Ge{sub x}/Si heterojunction devices have been realized. For example, among those realized are avalanche photodiodes, modulation-doped field-effect transistors, heterojunction bipolar transistors, and more recently, resonant tunneling structures, hot-carrier transistors, and quantum well metal-oxide-semiconductor field-effect transistors. In this paper several quantum size effects in strained Si{sub 1-x}Ge{sub x} layers and their potential in device applications will be reviewed. Among those to be discussed are resonant tunneling, miniband transport, and intersubband absorption in Si{sub 1-x}Ge{sub x}/Si superlattice structures, optical properties of monolayer Si{sub m}Ge{sub n} superlattices, and observation of large Stark effect associated with interband transition between quantized states in Si{sub 1-x}Ge{sub x}/Si quantum well structures.

  15. The Facts on Bipolar Disorder and FDA-Approved Treatments

    Science.gov (United States)

    ... Home For Consumers Consumer Updates The Facts on Bipolar Disorder and FDA-Approved Treatments Share Tweet Linkedin ... to top What to Do if You Suspect Bipolar Disorder If you suspect you have a bipolar ...

  16. Simulation of bipolar charge transport in nanocomposite polymer films

    Science.gov (United States)

    Lean, Meng H.; Chu, Wei-Ping L.

    2015-03-01

    This paper describes 3D particle-in-cell simulation of bipolar charge injection and transport through nanocomposite film comprised of ferroelectric ceramic nanofillers in an amorphous polymer matrix. The classical electrical double layer (EDL) model for a monopolar core is extended (eEDL) to represent the nanofiller by replacing it with a dipolar core. Charge injection at the electrodes assumes metal-polymer Schottky emission at low to moderate fields and Fowler-Nordheim tunneling at high fields. Injected particles migrate via field-dependent Poole-Frenkel mobility and recombine with Monte Carlo selection. The simulation algorithm uses a boundary integral equation method for solution of the Poisson equation coupled with a second-order predictor-corrector scheme for robust time integration of the equations of motion. The stability criterion of the explicit algorithm conforms to the Courant-Friedrichs-Levy limit assuring robust and rapid convergence. The model is capable of simulating a wide dynamic range spanning leakage current to pre-breakdown. Simulation results for BaTiO3 nanofiller in amorphous polymer matrix indicate that charge transport behavior depend on nanoparticle polarization with anti-parallel orientation showing the highest leakage conduction and therefore lowest level of charge trapping in the interaction zone. Charge recombination is also highest, at the cost of reduced leakage conduction charge. The eEDL model predicts the meandering pathways of charge particle trajectories.

  17. Course of Subthreshold Bipolar Disorder in Youth: Diagnostic Progression from Bipolar Disorder Not Otherwise Specified

    Science.gov (United States)

    Axelson, David A.; Birmaher, Boris; Strober, Michael A.; Goldstein, Benjamin I.; Ha, Wonho; Gill, Mary Kay; Goldstein, Tina R.; Yen, Shirley; Hower, Heather; Hunt, Jeffrey I.; Liao, Fangzi; Iyengar, Satish; Dickstein, Daniel; Kim, Eunice; Ryan, Neal D.; Frankel, Erica; Keller, Martin B.

    2011-01-01

    Objective: To determine the rate of diagnostic conversion from an operationalized diagnosis of bipolar disorder not otherwise specified (BP-NOS) to bipolar I disorder (BP-I) or bipolar II disorder (BP-II) in youth over prospective follow-up and to identify factors associated with conversion. Method: Subjects were 140 children and adolescents…

  18. Bipolar Disorder and Obsessive Compulsive Disorder Comorbidity

    Directory of Open Access Journals (Sweden)

    Necla Keskin

    2014-08-01

    Full Text Available The comorbidity of bipolar disorder and anxiety disorders is a well known concept. Obsessive-compulsive disorder is the most commonly seen comorbid anxiety disorder in bipolar patients. Some genetic variants, neurotransmitters especially serotonergic systems and second-messenger systems are thought to be responsible for its etiology. Bipolar disorder alters the clinical aspects of obsessive compulsive disorder and is associated with poorer outcome. The determination of comorbidity between bipolar disorder and obsessive compulsive disorder is quite important for appropriate clinical management and treatment. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2014; 6(4.000: 429-437

  19. [Lithium and anticonvulsants in bipolar depression].

    Science.gov (United States)

    Samalin, L; Nourry, A; Llorca, P-M

    2011-12-01

    For decades, lithium and anticonvulsants have been widely used in the treatment of bipolar disorder. Their efficacy in the treatment of mania is recognized. These drugs have been initially evaluated in old and methodologically heterogeneous studies. Their efficacy in bipolar depression has not always been confirmed in more recent and methodologically more reliable studies. Thus, lithium's efficacy as monotherapy was challenged by the study of Young (2008) that showed a lack of efficacy compared with placebo in the treatment of bipolar depression. In two recent meta-analyses, valproate has shown a modest efficacy in the treatment of bipolar depression. As for lithium, valproate appeared to have a larger antimanic effect for acute phase and prophylaxis of bipolar disorder. In contrast, lamotrigine is more effective on the depressive pole of bipolar disorder with better evidence for the prevention of depressive recurrences. The guidelines include these recent studies and recommend lamotrigine as a first-line treatment of bipolar depression and for maintenance treatment. Because of more discordant data concerning lithium and valproate, these two drugs are placed either as first or as second line treatment of bipolar depression. The different safety/efficacy ratios of mood stabilizers underlie the complementarity and the importance of combination between them, or with some second-generation antipsychotics, in the treatment of patients with bipolar disorder.

  20. Virginia Woolf, neuroprogression, and bipolar disorder.

    Science.gov (United States)

    Boeira, Manuela V; Berni, Gabriela de Á; Passos, Ives C; Kauer-Sant'Anna, Márcia; Kapczinski, Flávio

    2017-01-01

    Family history and traumatic experiences are factors linked to bipolar disorder. It is known that the lifetime risk of bipolar disorder in relatives of a bipolar proband are 5-10% for first degree relatives and 40-70% for monozygotic co-twins. It is also known that patients with early childhood trauma present earlier onset of bipolar disorder, increased number of manic episodes, and more suicide attempts. We have recently reported that childhood trauma partly mediates the effect of family history on bipolar disorder diagnosis. In light of these findings from the scientific literature, we reviewed the work of British writer Virginia Woolf, who allegedly suffered from bipolar disorder. Her disorder was strongly related to her family background. Moreover, Virginia Woolf was sexually molested by her half siblings for nine years. Her bipolar disorder symptoms presented a pernicious course, associated with hospitalizations, suicidal behavioral, and functional impairment. The concept of neuroprogression has been used to explain the clinical deterioration that takes places in a subgroup of bipolar disorder patients. The examination of Virgina Woolf's biography and art can provide clinicians with important insights about the course of bipolar disorder.

  1. Virginia Woolf, neuroprogression, and bipolar disorder

    Directory of Open Access Journals (Sweden)

    Manuela V. Boeira

    2016-01-01

    Full Text Available Family history and traumatic experiences are factors linked to bipolar disorder. It is known that the lifetime risk of bipolar disorder in relatives of a bipolar proband are 5-10% for first degree relatives and 40-70% for monozygotic co-twins. It is also known that patients with early childhood trauma present earlier onset of bipolar disorder, increased number of manic episodes, and more suicide attempts. We have recently reported that childhood trauma partly mediates the effect of family history on bipolar disorder diagnosis. In light of these findings from the scientific literature, we reviewed the work of British writer Virginia Woolf, who allegedly suffered from bipolar disorder. Her disorder was strongly related to her family background. Moreover, Virginia Woolf was sexually molested by her half siblings for nine years. Her bipolar disorder symptoms presented a pernicious course, associated with hospitalizations, suicidal behavioral, and functional impairment. The concept of neuroprogression has been used to explain the clinical deterioration that takes places in a subgroup of bipolar disorder patients. The examination of Virgina Woolf’s biography and art can provide clinicians with important insights about the course of bipolar disorder.

  2. Vacancy Structures and Melting Behavior in Rock-Salt GeSbTe

    OpenAIRE

    Bin Zhang; Xue-Peng Wang; Zhen-Ju Shen; Xian-Bin Li; Chuan-Shou Wang; Yong-Jin Chen; Ji-Xue Li; Jin-Xing Zhang; Ze Zhang; Sheng-Bai Zhang; Xiao-Dong Han

    2016-01-01

    Ge-Sb-Te alloys have been widely used in optical/electrical memory storage. Because of the extremely fast crystalline-amorphous transition, they are also expected to play a vital role in next generation nonvolatile microelectronic memory devices. However, the distribution and structural properties of vacancies have been one of the key issues in determining the speed of melting (or amorphization), phase-stability, and heat-dissipation of rock-salt GeSbTe, which is crucial for its technological...

  3. Containerless processing of amorphous ceramics

    Science.gov (United States)

    Weber, J. K. Richard; Krishnan, Shankar; Schiffman, Robert A.; Nordine, Paul C.

    1990-01-01

    The absence of gravity allows containerless processing of materials which could not otherwise be processed. High melting point, hard materials such as borides, nitrides, and refractory metals are usually brittle in their crystalline form. The absence of dislocations in amorphous materials frequently endows them with flexibility and toughness. Systematic studies of the properties of many amorphous materials have not been carried out. The requirements for their production is that they can be processed in a controlled way without container interaction. Containerless processing in microgravity could permit the control necessary to produce amorphous forms of hard materials.

  4. Noise Parameter Analysis of SiGe HBTs for Different Sizes in the Breakdown Region

    Directory of Open Access Journals (Sweden)

    Chie-In Lee

    2016-01-01

    Full Text Available Noise parameters of silicon germanium (SiGe heterojunction bipolar transistors (HBTs for different sizes are investigated in the breakdown region for the first time. When the emitter length of SiGe HBTs shortens, minimum noise figure at breakdown decreases. In addition, narrower emitter width also decreases noise figure of SiGe HBTs in the avalanche region. Reduction of noise performance for smaller emitter length and width of SiGe HBTs at breakdown resulted from the lower noise spectral density resulting from the breakdown mechanism. Good agreement between experimental and simulated noise performance at breakdown is achieved for different sized SiGe HBTs. The presented analysis can benefit the RF circuits operating in the breakdown region.

  5. Electrophysical Properties of Ge-Sb-Te Thin Films for Phase Change Memory Devices

    Science.gov (United States)

    Lazarenko, P. I.; Kozyukhin, S. A.; Sherchenkov, A. A.; Babich, A. V.; Timoshenkov, S. P.; Gromov, D. G.; Zabolotskaya, A. V.; Kozik, V. V.

    2017-01-01

    In this work, we studied temperature dependences of the resistivity and current-voltage characteristics of amorphous thin films based on the materials of a Ge-Sb-Te system of compositions GeSb4Te7 (GST147), GeSb2Te4 (GST124), and Ge2Sb2Te5 (GST225) applied in the phase change memory devices. The effect of changes in the composition of thin films on the crystallization temperature, resistivity of films in amorphous and crystalline states, and on the activation energy of conductivity is determined. It is found that the peculiarity of these materials is the mechanism of two-channel conductivity where the contribution to the conductivity is made by charge carriers excited into localized states in the band tails and by carriers of the delocalized states in the valence band.

  6. Structural details of Ge-rich and silver-doped chalcogenide glasses for nanoionic nonvolatile memory

    Energy Technology Data Exchange (ETDEWEB)

    Mitkova, Maria [Department of Electrical and Computer Engineering, Boise State University, Boise, Idaho 83725 (United States); Sakaguchi, Yoshifumi [Department of Electrical and Computer Engineering, Boise State University, Boise, Idaho 83725 (United States); JAEA, 2-4 Shirane, Shirakata, Tokai-mura Naka-gun, Ibaraki 319-1195 (Japan); Tenne, Dmitri [Department of Physics, Boise State University, 1910 University Dr., Boise, Idaho 83725-1570 (United States); Bhagat, Shekhar Kumar; Alford, Terry L. [School of Materials, Arizona State University, Tempe, Arizona 85287-8706 (United States)

    2010-03-15

    We are reporting our results of Raman and X-ray diffraction (XRD) studies on amorphous Ge{sub 46}S{sub 54} thin films and the films after silver photodiffusion. Based on the Raman scattering studies, a structural model for amorphous Ge{sub 46}S{sub 54} is suggested including the formation of single Ge-S chains with a vibrational mode at 410 cm{sup -1}. The result of XRD measurement indicates that there exists a medium-range order with about 6 A and acute; even at such Ge-rich composition. After the introduction of silver, the medium-range order is lost and there was a change in the diffraction curve indicative of the change in the local atomic order. The experimental results are explained in terms of our structural model, in connection with the application for fast switching memory devices. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Effect of crystalline/amorphous interfaces on thermal transport across confined thin films and superlattices

    Science.gov (United States)

    Giri, Ashutosh; Braun, Jeffrey L.; Hopkins, Patrick E.

    2016-06-01

    We report on the thermal boundary resistances across crystalline and amorphous confined thin films and the thermal conductivities of amorphous/crystalline superlattices for Si/Ge systems as determined via non-equilibrium molecular dynamics simulations. Thermal resistances across disordered Si or Ge thin films increase with increasing length of the interfacial thin films and in general demonstrate higher thermal boundary resistances in comparison to ordered films. However, for films ≲3 nm, the resistances are highly dependent on the spectral overlap of the density of states between the film and leads. Furthermore, the resistances at a single amorphous/crystalline interface in these structures are much lower than those at interfaces between the corresponding crystalline materials, suggesting that diffusive scattering at an interface could result in higher energy transmissions in these systems. We use these findings, together with the fact that high mass ratios between amorphous and crystalline materials can lead to higher thermal resistances across thin films, to design amorphous/crystalline superlattices with very low thermal conductivities. In this regard, we study the thermal conductivities of amorphous/crystalline superlattices and show that the thermal conductivities decrease monotonically with increasing interface densities above 0.1 nm-1. These thermal conductivities are lower than that of the homogeneous amorphous counterparts, which alludes to the fact that interfaces non-negligibly contribute to thermal resistance in these superlattices. Our results suggest that the thermal conductivity of superlattices can be reduced below the amorphous limit of its material constituent even when one of the materials remains crystalline.

  8. Poorer sustained attention in bipolar I than bipolar II disorder

    Directory of Open Access Journals (Sweden)

    Chen Shih-Heng

    2010-02-01

    Full Text Available Abstract Background Nearly all information processing during cognitive processing takes place during periods of sustained attention. Sustained attention deficit is among the most commonly reported impairments in bipolar disorder (BP. The majority of previous studies have only focused on bipolar I disorder (BP I, owing to underdiagnosis or misdiagnosis of bipolar II disorder (BP II. With the refinement of the bipolar spectrum paradigm, the goal of this study was to compare the sustained attention of interepisode patients with BP I to those with BP II. Methods In all, 51 interepisode BP patients (22 with BP I and 29 with BP II and 20 healthy controls participated in this study. The severity of psychiatric symptoms was assessed by the 17-item Hamilton Depression Rating Scale and the Young Mania Rating Scale. All participants undertook Conners' Continuous Performance Test II (CPT-II to evaluate sustained attention. Results After controlling for the severity of symptoms, age and years of education, BP I patients had a significantly longer reaction times (F(2,68 = 7.648, P = 0.001, worse detectability (d' values (F(2,68 = 6.313, P = 0.003 and more commission errors (F(2,68 = 6.182, P = 0.004 than BP II patients and healthy controls. BP II patients and controls scored significantly higher than BP I patients for d' (F = 6.313, P = 0.003. No significant difference was found among the three groups in omission errors and no significant correlations were observed between CPT-II performance and clinical characteristics in the three groups. Conclusions These findings suggested that impairments in sustained attention might be more representative of BP I than BP II after controlling for the severity of symptoms, age, years of education and reaction time on the attentional test. A longitudinal follow-up study design with a larger sample size might be needed to provide more information on chronological sustained attention deficit in BP patients, and to illustrate

  9. Apatite Formation from Amorphous Calcium Phosphate and Mixed Amorphous Calcium Phosphate/Amorphous Calcium Carbonate.

    Science.gov (United States)

    Ibsen, Casper J S; Chernyshov, Dmitry; Birkedal, Henrik

    2016-08-22

    Crystallization from amorphous phases is an emerging pathway for making advanced materials. Biology has made use of amorphous precursor phases for eons and used them to produce structures with remarkable properties. Herein, we show how the design of the amorphous phase greatly influences the nanocrystals formed therefrom. We investigate the transformation of mixed amorphous calcium phosphate/amorphous calcium carbonate phases into bone-like nanocrystalline apatite using in situ synchrotron X-ray diffraction and IR spectroscopy. The speciation of phosphate was controlled by pH to favor HPO4 (2-) . In a carbonate free system, the reaction produces anisotropic apatite crystallites with large aspect ratios. The first formed crystallites are highly calcium deficient and hydrogen phosphate rich, consistent with thin octacalcium phosphate (OCP)-like needles. During growth, the crystallites become increasingly stoichiometric, which indicates that the crystallites grow through addition of near-stoichiometric apatite to the OCP-like initial crystals through a process that involves either crystallite fusion/aggregation or Ostwald ripening. The mixed amorphous phases were found to be more stable against phase transformations, hence, the crystallization was inhibited. The resulting crystallites were smaller and less anisotropic. This is rationalized by the idea that a local phosphate-depletion zone formed around the growing crystal until it was surrounded by amorphous calcium carbonate, which stopped the crystallization.

  10. Amorphous drugs and dosage forms

    DEFF Research Database (Denmark)

    Grohganz, Holger; Löbmann, K.; Priemel, P.;

    2013-01-01

    formulation principles are needed to ensure the stability of amorphous drug forms. The formation of solid dispersions is still the most investigated approach, but additional approaches are desirable to overcome the shortcomings of solid dispersions. Spatial separation by either coating or the use of micro......The transformation to an amorphous form is one of the most promising approaches to address the low solubility of drug compounds, the latter being an increasing challenge in the development of new drug candidates. However, amorphous forms are high energy solids and tend to recry stallize. New......-containers has shown potential to prevent or delay recrystallization. Another recent approach is the formation of co-amorphous mixtures between either two drugs or one drug and one low molecular weight excipient. Molecular interactions between the two molecules provide an energy barrier that has to be overcome...

  11. Conducting state of GeTe by defect-induced topological insulating order

    Science.gov (United States)

    Kim, Jinwoong; Jhi, Seung-Hoon

    2012-02-01

    Topological insulating order protected by time-reversal symmetry is robust under structural disorder. Interestingly, recent studies on phase change materials like GeSbTe showed that their topological insulating order is sensitive to atomic stacking sequences. It was also shown that their structural phase transition is correlated with topological insulating order. GeTe, a well-known phase change material, is trivial insulator in its equilibrium structure. In this study, we discuss how atomic defects such as Ge tetrahedral defect observed in amorphous GeTe can change its topological insulating order based on first-principles calculations and model Hamiltonian. We also investigated the critical density of such tetrahedral defects to induce topological insulating order in GeTe. Our study will help explore hidden orders in GeTe.

  12. Boron doping compensation of hydrogenated amorphous and polymorphous germanium thin films for infrared detection applications

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, M., E-mail: mmoreno@inaoep.mx [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico); Delgadillo, N. [Universidad Autónoma de Tlaxcala, Av. Universidad No. 1, Z. P. 90006 Tlaxcala (Mexico); Torres, A. [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico); Ambrosio, R. [Technology and Engineering Institute, Ciudad Juarez University UACJ, Av. Del Charro 450N, Z. P. 32310 Chihuahua (Mexico); Rosales, P.; Kosarev, A.; Reyes-Betanzo, C.; Hidalga-Wade, J. de la; Zuniga, C.; Calleja, W. [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico)

    2013-12-02

    In this work we have studied boron doping of hydrogenated amorphous germanium a-Ge:H and polymorphous germanium (pm-Ge:H) in low regimes, in order to compensate the material from n-type (due to oxygen contamination that commonly occurs during plasma deposition) to intrinsic, and in this manner improve the properties that are important for infrared (IR) detection, as activation energy (E{sub a}) and temperature coefficient of resistance (TCR). Electrical, structural and optical characterization was performed on the films produced. Measurements of the temperature dependence of conductivity, room temperature conductivity (σ{sub RT}), E{sub a} and current–voltage characteristics under IR radiation were performed in the compensated a-Ge:H and pm-Ge:H films. Our results demonstrate that, effectively, the values of E{sub a}, TCR and IR detection are improved on the a-Ge:H/pm-Ge:H films, using boron doping in low regimes, which results of interest for infrared detectors. - Highlights: • We reported boron doping compensation of amorphous and polymorphous germanium. • The films were deposited by plasma enhanced chemical vapor deposition. • The aim is to use the films as thermo-sensing elements in un-cooled microbolometers. • Those films have advantages over boron doped a-Si:H used in commercial detectors.

  13. Transient Stuttering in Catatonic Bipolar Patients

    Directory of Open Access Journals (Sweden)

    Anthony B. Joseph

    1991-01-01

    Full Text Available Two cases of transient stuttering occurring in association with catatonia and bipolar disorder are described. Affective decompensation has been associated with lateralized cerebral dysfunction, and it is hypothesized that in some bipolar catatonic patients a concomitant disorder of the lateralization of language function may lead to a variety of clinical presentations including aphasia, mutism, and stuttering.

  14. Swimming in Deep Water: Childhood Bipolar Disorder

    Science.gov (United States)

    Senokossoff, Gwyn W.; Stoddard, Kim

    2009-01-01

    The authors focused on one parent's struggles in finding a diagnosis and intervention for a child who had bipolar disorder. The authors explain the process of identification, diagnosis, and intervention of a child who had bipolar disorder. In addition to the personal story, the authors provide information on the disorder and outline strategies…

  15. Heritability of bipolar affective disorder: Family study

    Directory of Open Access Journals (Sweden)

    Obradović Tanja

    2011-01-01

    Full Text Available Background/Aim. Bipolar affective disorder is mental disorder with polygenic type of heredity. Heritability - relation between genetic and environmental variance is used to estimate the level of influence of genetic variance to phenotype variance. Study results show decreasing trend in the value of heritability of bipolar affective disorder, thus indicating that this disorder is a complex behavioral threshold characteristic. Therefore, the aim of this study was to estimate the contribution of genetic variance to phenotype variance of bipolar affective disorder, i.e. to estimate heritability of this disorder. Methods. By the use of a questionnaire, 80 patients with over crossed threshold for bipolar affective disorder were asked for functional information about the members of their families belonging to the first degree of relation (fathers, mothers and full- sibs. By using ”Applet for calculating heritability for threshold traits (disease“, and regression analysis, heritability of bipolar affective disorder as well as its statistical significance, were estimated (χ2 test. Results. Heritability and relationship of genetic and environmental variance of bipolar affective disorder is 0.2 with statistically significant difference from zero (p < 0.001. Conclusion. The estimated contribution of genetic variance to phenotype variance of bipolar affective disorder is low being 20%, while the contribution of environmental variance is 80%. This result contributes to the understanding of bipolar affective disorder as a complex behavioral threshold trait.

  16. GeSn/Ge multiquantum well photodetectors on Si substrates.

    Science.gov (United States)

    Oehme, M; Widmann, D; Kostecki, K; Zaumseil, P; Schwartz, B; Gollhofer, M; Koerner, R; Bechler, S; Kittler, M; Kasper, E; Schulze, J

    2014-08-15

    Vertical incidence GeSn/Ge multiquantum well (MQW) pin photodetectors on Si substrates were fabricated with a Sn concentration of 7%. The epitaxial structure was grown with a special low temperature molecular beam epitaxy process. The Ge barrier in the GeSn/Ge MQW was kept constant at 10 nm. The well width was varied between 6 and 12 nm. The GeSn/Ge MQW structures were grown pseudomorphically with the in-plane lattice constant of the Ge virtual substrate. The absorption edge shifts to longer wavelengths with thicker QWs in agreement with expectations from smaller quantization energies for the thicker QWs.

  17. Bipolar Ag-Zn battery

    Science.gov (United States)

    Giltner, L. John

    1994-02-01

    The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected

  18. Creative treatment of bipolar disorders.

    Science.gov (United States)

    Tavčar, Rok

    2015-09-01

    Bipolar disorder is a mental disorder with chronic and remitting course. The disorder is related to high mortality and severely impairs everyday functioning. Therefore a scientifically sound and practical approach to treatment is needed. Making a long-term treatment plan usually also demands some creativity. The patient is interested in a number of issues, from the choice of therapy in acute phases to long-term treatment. Usual questions are how long shall I take the medications, do I really need all those pills or can we decrease the dosage of some drugs? This paper discussed the above mentioned questions in light of latest publications in this field.

  19. Personality trait predictors of bipolar disorder symptoms.

    Science.gov (United States)

    Quilty, Lena Catherine; Sellbom, Martin; Tackett, Jennifer Lee; Bagby, Robert Michael

    2009-09-30

    The purpose of the current investigation was to examine the personality predictors of bipolar disorder symptoms, conceptualized as one-dimensional (bipolarity) or two-dimensional (mania and depression). A psychiatric sample (N=370; 45% women; mean age 39.50 years) completed the Revised NEO Personality Inventory and the Minnesota Multiphasic Personality Inventory -2. A model in which bipolar symptoms were represented as a single dimension provided a good fit to the data. This dimension was predicted by Neuroticism and (negative) Agreeableness. A model in which bipolar symptoms were represented as two separate dimensions of mania and depression also provided a good fit to the data. Depression was associated with Neuroticism and (negative) Extraversion, whereas mania was associated with Neuroticism, Extraversion and (negative) Agreeableness. Symptoms of bipolar disorder can be usefully understood in terms of two dimensions of mania and depression, which have distinct personality correlates.

  20. Diagnostic stability in pediatric bipolar disorder

    DEFF Research Database (Denmark)

    Vedel Kessing, Lars; Vradi, Eleni; Andersen, Per Kragh

    2015-01-01

    BACKGROUND: The diagnostic stability of pediatric bipolar disorder has not been investigated previously. The aim was to investigate the diagnostic stability of the ICD-10 diagnosis of pediatric mania/bipolar disorder.METHODS: All patients below 19 years of age who got a diagnosis of mania/bipolar...... disorder at least once in a period from 1994 to 2012 at psychiatric inpatient or outpatient contact in Denmark were identified in a nationwide register.RESULTS: Totally, 354 children and adolescents got a diagnosis of mania/bipolar disorder at least once; a minority, 144 patients (40.7%) got the diagnosis...... at the first contact whereas the remaining patients (210; 59.3%) got the diagnosis at later contacts before age 19. For the latter patients, the median time elapsed from first treatment contact with the psychiatric service system to the first diagnosis with a manic episode/bipolar disorder was nearly 1 year...

  1. Dielectric Function and Critical Point of GeSbTe Pseudo-binary Compound Thin Films

    Science.gov (United States)

    Lee, Hosun; Park, Jun-Woo; Kang, Youn-Seon; Lee, Tae-Yon; Suh, Dong-Seok; Kim, Ki-Joon; Kim, Cheol Kyu; Kang, Yoon Ho; da Silva, Juarez L. F.

    2009-03-01

    We measure the dielectric functions of GeSbTe pseudo-binary thin films by using spectroscopic ellipsometry. We anneal the thin films at various temperatures. According to x-ray diffraction, the as-grown thin films are amorphous and the annealed films have metastable and stable crystalline phases. By using standard critical point model, we obtain the accurate values of the energy gap of the amorphous phase as well as the critical point energies of the crystalline thin films. The critical point energies are compared to the band gap energies determined by the method of linear extrapolation of the optical absorption. As the Sb to Ge atomic ratio increases, the optical (band) gap energy of amorphous (crystalline) phase decreases. Standard critical point fitting show several higher band gaps. The electronic band structures and the dielectric functions of the thin films are calculated by using density functional theory and are compared to the measured ones. The band structure calculations show in stable phase that GeTe, Ge2Sb2Te5, and Ge1Sb2Te4 have indirect gap whereas Ge1Sb4Te7 and Sb2Te3 have direct gap. The measured indirect band gap energies match well with the electronic band structure calculations.

  2. Raman spectra and XPS studies of phase changes in Ge2Sb2Te5 films

    Institute of Scientific and Technical Information of China (English)

    Liu Bo; Song Zhi-Tang; Zhang Ting; Feng Song-Lin; Chen Bomy

    2004-01-01

    Ge2Sb2Te5 film was deposited by RF magnetron sputtering on Si (100) substrate. The structure of amorphous and crystalline Ge2Sb2Te5 thin films was investigated using XRD, Raman spectra and XPS. XRD measurements revealed the existence of two different crystalline phases, which has a FCC structure and a hexagonal structure, respectively.The broad peak in the Raman spectra of amorphous Ge2Sb2Te5 film is due to the amorphous -Te-Te- stretching. As the annealing temperature increases, the broad peak separates into two peaks, which indicates that the heteropolar bond in GeTe4 and the Sb-Sb bond are connected with four Te atoms, and other units such as (TeSb) Sb-Sb (Te2)and (Sb2) Sb-Sb (Te2), where some of the four Te atoms in the above formula are replaced by Sb atoms, remain in crystalline Ge2Sb2Te5 thin film. And from the results of Raman spectra and XPS, higher the annealing temperature,more Te atoms bond to Ge atoms and more Sb atoms substitute Te in (Te2) Sb-Sb (Te2).

  3. Study of Ge2Sb2Te5 Film for Nonvolatile Memory Medium

    Institute of Scientific and Technical Information of China (English)

    Baowei QIAO; Yunfeng LAI; Jie FENG; Yun LING; Yinyin LIN; Ting'ao TANG; Bingchu CAI; Bomy CHEN

    2005-01-01

    The amorphous Ge2Sb2Te5 film with stoichiometric compositions was deposited by co-sputtering of separate Ge,Sb, and Te targets on SiO2/Si (100) wafer in ultrahigh vacuum magnetron sputtering apparatus. The crystallization behavior of amorphous Ge2Sb2Te5 film was investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). With an increase of annealing temperature, the amorphous Ge2Sb2Te5 film undergoes a two-step crystallization process that it first crystallizes in face-centered-cubic (fcc) crystal structure and finally fcc structure changes to hexagonal (hex) structure. Activation energy values of 3.636±0.137and 1.579±0.005 eV correspond to the crystallization and structural transformation processes, respectively. From annealing temperature dependence of the film resistivity, it is determined th at the first steep decrease of the resistivity corresponds to crystallization while the second one is primarily caused by structural transformation from "fcc"to "hex" and growth of the crystal grains. Current-voltage (I-V) characteristics of the device with 40 nm-thick Ge2Sb2Te5 film show that the Ge2Sb2Te5 film with nanometer order thickness is still applicable for memory medium of nonvolatile phase change memory.

  4. A SiGe BiCMOS double-balanced mixer with active balun for X-band Doppler radar

    DEFF Research Database (Denmark)

    Michaelsen, Rasmus S.; Johansen, Tom K.; Tamborg, Kjeld M.

    2015-01-01

    In this paper, we present an X-band doublebalanced mixer in SiGe BiCMOS technology. The mixer core consists of a LO Matched quad diode ring using diode-connected Heterojunction Bipolar Transistors (HBTs). The mixer is integrated with a low-noise, high-linearity active balun on the RF port and a m...

  5. Bipolar disorder: staging and neuroprogression

    Directory of Open Access Journals (Sweden)

    Rodrigues, Aline André

    2014-04-01

    Full Text Available In bipolar disorder illness progression has been associated with a higher number of mood episodes and hospitalizations, poorer response to treatment, and more severe cognitive and functional impairment. This supports the notion of the use of staging models in this illness. The value of staging models has long been recognized in many medical and malignant conditions. Staging models rely on the fact that different interventions may suit different stages of the disorder, and that better outcomes can be obtained if interventions are implemented earlier in the course of illness. Thus, treatment planning would benefit from the assessment of cognition, functioning and comorbidities. Staging may offer a means to refine treatment options, and most importantly, to establish a more precise diagnosis. Moreover, staging could have utility as course specifier and may guide treatment planning and better information to patients and their family members of what could be expected in terms of prognosis. The present study reviews the clinical and biological basis of the concept of illness progression in bipolar disorder.

  6. Degradation of SiGe devices by proton irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ohyama, Hidenori; Hayama, Kiyoteru [Kumamoto National Coll. of Technology, Nishigoshi (Japan); Vanhellemont, J.; Takami, Yasukiyo; Sunaga, Hiromi; Nashiyama, Isamu; Uwatoko, Yoshiya; Poortmans, J.; Caymax, M.

    1997-03-01

    The degradation and recovery behavior of strained Si{sub 1-x}Ge{sub x} diodes and heterojunction bipolar transistors (HBTs) by irradiated by protons are studied. The degradation of device performance and the generation of lattice defects are reported as a function of fluence and germanium content and also compared extensively with previous results obtained on electron and neutron irradiated devices. In order to study the recovery behavior of the irradiated devices, isochronal annealing is performed. The radiation source dependence of the degradation is discussed taking into account the number of knock-on atoms and the nonionizing energy loss (NIEL). (author)

  7. Electronic transport in amorphous phase-change materials

    Energy Technology Data Exchange (ETDEWEB)

    Luckas, Jennifer Maria

    2012-09-14

    Phase change materials combine a pronounced contrast in resistivity and reflectivity between their disordered amorphous and ordered crystalline state with very fast crystallization kinetics. Due to this exceptional combination of properties phase-change materials find broad application in non-volatile optical memories such as CD, DVD or Bluray Disc. Furthermore, this class of materials demonstrates remarkable electrical transport phenomena in their disordered state, which have shown to be crucial for their application in electronic storage devices. The threshold switching phenomenon denotes the sudden decrease in resistivity beyond a critical electrical threshold field. The threshold switching phenomenon facilitates the phase transitions at practical small voltages. Below this threshold the amorphous state resistivity is thermally activated and is observed to increase with time. This effect known as resistance drift seriously hampers the development of multi-level storage devices. Hence, understanding the physical origins of threshold switching and resistance drift phenomena is crucial to improve non-volatile phase-change memories. Even though both phenomena are often attributed to localized defect states in the band gap, the defect state density in amorphous phase-change materials has remained poorly studied. Starting from a brief introduction of the physics of phase-change materials this thesis summarizes the most important models behind electrical switching and resistance drift with the aim to discuss the role of localized defect states. The centerpiece of this thesis is the investigation of defects state densities in different amorphous phase-change materials and electrical switching chalcogenides. On the basis of Modulated Photo Current (MPC) Experiments and Photothermal Deflection Spectroscopy, a sophisticated band model for the disordered phase of the binary phase-change alloy GeTe has been developed. By this direct experimental approach the band-model for a-Ge

  8. Ferromagnetic Fe-based Amorphous Alloy with High Glass-forming Ability

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A ferromagnetic amorphous Fe73Al4Ge2Nb1P10C6B4 alloy with highglass-forming ability was synthesized by melt spinning. The supercooled liquid region before crystallization reaches about 65.7 K. The crystallized structure consists of α-Fe, Fe3B, FeB, Fe3P and Fe3C phases. The Febased amorphous alloy exhibits good magnetic properties with a high saturation magnetization and a low saturated magnetostriction. The crystallization leads to an obvious decrease in the soft magnetic properties.

  9. Epitaxial growth of Ge-Sb-Te based phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Perumal, Karthick

    2013-07-30

    Ge-Sb-Te based phase change materials are considered as a prime candidate for optical and electrical data storage applications. With the application of an optical or electrical pulse, they can be reversibly switched between amorphous and crystalline state, thereby exhibiting large optical and electrical contrast between the two phases, which are then stored as information in the form of binary digits. Single crystalline growth is interesting from both the academic and industrial perspective, as ordered Ge-Sb-Te based metamaterials are known to exhibit switching at reduced energies. The present study deals with the epitaxial growth and analysis of Ge-Sb-Te based thin films. The first part of the thesis deals with the epitaxial growth of GeTe. Thin films of GeTe were grown on highly mismatched Si(111) and (001) substrates. On both the substrate orientations the film grows along [111] direction with an amorphous-to-crystalline transition observed during the initial stages of growth. The amorphous-to-crystalline transition was studied in-vivo using azimuthal reflection high-energy electron diffraction scans and grazing incidence X-ray diffraction. In the second part of the thesis epitaxy and characterization of Sb{sub 2}Te{sub 3} thin films are presented. The third part of the thesis deals with the epitaxy of ternary Ge-Sb-Te alloys. The composition of the films are shown to be highly dependent on growth temperatures and vary along the pseudobinary line from Sb{sub 2}Te{sub 3} to GeTe with increase in growth temperatures. A line-of-sight quadrupole mass spectrometer was used to reliably control the GeSbTe growth temperature. Growth was performed at different Ge, Sb, Te fluxes to study the compositional variation of the films. Incommensurate peaks are observed along the [111] direction by X-ray diffraction. The possibility of superstructural vacancy ordering along the [111] direction is discussed.

  10. Ultrathin GeSn p-channel MOSFETs grown directly on Si(111) substrate using solid phase epitaxy

    Science.gov (United States)

    Maeda, Tatsuro; Jevasuwan, Wipakorn; Hattori, Hiroyuki; Uchida, Noriyuki; Miura, Shu; Tanaka, Masatoshi; Santos, Nuno D. M.; Vantomme, André; Locquet, Jean-Pierre; Lieten, Ruben R.

    2015-04-01

    Ultrathin GeSn layers with a thickness of 5.5 nm are fabricated on a Si(111) substrate by solid phase epitaxy (SPE) of amorphous GeSn layers with Sn concentrations up to 6.7%. We demonstrate well-behaved depletion-mode operation of GeSn p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with an on/off ratio of more than 1000 owing to the ultrathin GeSn channel layer (5.5 nm). It is found that the on current increases significantly with increasing Sn concentration at the same gate overdrive, attributed to an increasing substitutional Sn incorporation in Ge. The GeSn (6.7%) layer sample shows approximately 90% enhancement in hole mobility in comparison with a pure Ge channel on Si.

  11. Tratamento do transtorno bipolar: eutimia Bipolar disorder treatment: euthymia

    Directory of Open Access Journals (Sweden)

    Fábio Gomes de Matos e Souza

    2005-01-01

    Full Text Available O transtorno bipolar é um quadro complexo caracterizado por episódios de depressão, mania ou hipomania e fases assintomáticas. O tratamento visa ao controle de episódios agudos e prevenção de novos episódios. O tratamento farmacológico iniciou-se com o lítio. Até o momento, o lítio permanece como o tratamento com mais evidências favoráveis na fase de manutenção. Outros tratamentos demonstram eficácia nessa fase, como o valproato, a carbamazepina e os antipsicóticos atípicos. Dos antipsicóticos atípicos o mais estudado nesta fase do tratamento é a olanzapina. Mais estudos prospectivos são necessários para confirmar a ação profilática de novos agentes.Bipolar disorder is a complex disorder characterized by depression episodes, mania or hypomania and asymptomatic phases. The treatment aims at the control of acute episodes and prevention of new episodes. The pharmacological treatment was inaugurated with lithium. Until the moment, lithium remains as the treatment with more favorable evidences in the maintenance phase. Other treatments demonstrate efficacy in this phase, as valproate, carbamazepine and atypical antipsychotics. Of the atypical antipsychotics, the most studied in this phase of treatment is olanzapine. More prospective studies are necessary to confirm prophylactic action of new agents.

  12. On coarse projective integration for atomic deposition in amorphous systems

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Claire Y., E-mail: yungc@seas.upenn.edu, E-mail: meister@unm.edu, E-mail: zepedaruiz1@llnl.gov; Sinno, Talid, E-mail: talid@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 South 33rd Street, 311A Towne Building, Philadelphia, Pennsylvania 19104 (United States); Han, Sang M., E-mail: yungc@seas.upenn.edu, E-mail: meister@unm.edu, E-mail: zepedaruiz1@llnl.gov [Department of Chemical and Biological Engineering, University of New Mexico, 1 University of New Mexico, MSC01 1120, Albuquerque, New Mexico 87131 (United States); Zepeda-Ruiz, Luis A., E-mail: yungc@seas.upenn.edu, E-mail: meister@unm.edu, E-mail: zepedaruiz1@llnl.gov [Lawrence Livermore National Laboratory, P.O. Box 808, L-367, Livermore, California 94550 (United States)

    2015-10-07

    Direct molecular dynamics simulation of atomic deposition under realistic conditions is notoriously challenging because of the wide range of time scales that must be captured. Numerous simulation approaches have been proposed to address the problem, often requiring a compromise between model fidelity, algorithmic complexity, and computational efficiency. Coarse projective integration, an example application of the “equation-free” framework, offers an attractive balance between these constraints. Here, periodically applied, short atomistic simulations are employed to compute time derivatives of slowly evolving coarse variables that are then used to numerically integrate differential equations over relatively large time intervals. A key obstacle to the application of this technique in realistic settings is the “lifting” operation in which a valid atomistic configuration is recreated from knowledge of the coarse variables. Using Ge deposition on amorphous SiO{sub 2} substrates as an example application, we present a scheme for lifting realistic atomistic configurations comprised of collections of Ge islands on amorphous SiO{sub 2} using only a few measures of the island size distribution. The approach is shown to provide accurate initial configurations to restart molecular dynamics simulations at arbitrary points in time, enabling the application of coarse projective integration for this morphologically complex system.

  13. Brief Report: A Family Risk Study Exploring Bipolar Spectrum Problems and Cognitive Biases in Adolescent Children of Bipolar Parents

    Science.gov (United States)

    Espie, Jonathan; Jones, Steven H.; Vance, Yvonne H.; Tai, Sara J.

    2012-01-01

    Children of parents with bipolar disorder are at increased risk of bipolar spectrum diagnoses. This cross-sectional study explores cognitive factors in the prediction of vulnerability to bipolar disorder. Adolescents at high-risk (with a parent with bipolar disorder; n = 23) and age and gender matched adolescents (n = 24) were recruited. Parent…

  14. The prestige model of spectrum bipolarity.

    Science.gov (United States)

    Le Bas, James; Newton, Richard; Sore, Rachel; Castle, David

    2015-02-01

    Because affective pathogenesis is a hard problem for psychiatry, it behoves researchers to develop and test novel models of causality. We examine the notion that the adaptive drive to social investment - prestige - provides clues to the bipolar spectrum. A seven node bipolar spectrum is proposed, based on a putative gradient of "bipolarity". It is conceived that this gradient may correlate with the drive to social investment (prestige). In order to test this hypothesis with proof of concept data, a case control study categorised 228 subjects into a seven node bipolar spectrum. Whilst controlling for mood elevation and depression, differences in strategic prestige (leadership) motivation (MSPM) between spectrum groups were examined. The bipolar I (S1) node had a greater strategic prestige (leadership) motivation score than the controls (S7) by 21.17 points, 95% CI [8.16, 34.18], pbipolar II (S2) node was higher than the control group by 16.73 points, 95% CI [0.92, 32.54], p=.030, d=0.84. Whilst the pseudounipolar (S3) node (those with depression and bipolar family histories; n=17) had only a marginally statistical difference in MSPM compared to controls (p=.051), the mean difference (16.98) and d value (0.86) indicated an elevated MSPM level. Prestige (leadership) motivation score positively correlated with dimensional lifetime bipolarity (Mood Disorder Questionnaire) score (rp=0.47), supporting the spectrum prestige motivation gradient notion. Evidence is presented for a genetic disposition to elevated strategic prestige (leadership) motivation. Sensitivity to Social Inclusion (MSIS), Contingency of Self-Worth (CSW.av) and tension significantly predicted strategic prestige (leadership) motivation (MSPM) score in a multiple regression. - suggesting that a vulnerability of the social self may be a feature of bipolar disorders. The prestige model of spectrum bipolarity offers a new conceptualisation of affective disorders and has received preliminary support.

  15. Ion beam synthesis of SiGe alloy layers

    Energy Technology Data Exchange (ETDEWEB)

    Im, Seongil [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    Procedures required for minimizing structural defects generated during ion beam synthesis of SiGe alloy layers were studied. Synthesis of 200 mm SiGe alloy layers by implantation of 120-keV Ge ions into <100> oriented Si wafers yielded various Ge peak concentrations after the following doses, 2 x 1016cm-2, 3 x 1016cm-2 (mid), and 5 x 1016cm-2 (high). Following implantation, solid phase epitaxial (SPE) annealing in ambient N2 at 800C for 1 hr. resulted in only slight redistribution of the Ge. Two kinds of extended defects were observed in alloy layers over 3 x l016cm-2cm dose at room temperature (RT): end-of-range (EOR) dislocation loops and strain-induced stacking faults. Density of EOR dislocation loops was much lower in alloys produced by 77K implantation than by RT implantation. Decreasing the dose to obtain 5 at% peak Ge concentration prevents strain relaxation, while those SPE layers with more than 7 at% Ge peak show high densities of misfit- induced stacking faults. Sequential implantation of C following high dose Ge implantation (12 at% Ge peak concentration in layer) brought about a remarkable decrease in density of misfit-induced stacking faults. For peak implanted C > 0.55 at%, stacking fault generation in the epitaxial layer was suppressed, owing to strain compensation by C atoms in the SiGe lattice. A SiGe alloy layer with 0.9 at% C peak concentration under a 12 at% Ge peak exhibited the best microstructure. Results indicate that optimum Ge/C ratio for strain compensation is between 11 and 22. The interface between amorphous and regrown phases (a/c interface) had a dramatic morphology change during its migration to the surface. Initial <100> planar interface decomposes into a <111> faceted interface, changing the growth kinetics; this is associated with strain relaxation by stacking fault formation on (111) planes in the a/c interface.

  16. Nuclear Magnetic Resonance Studies of Tellurium and Antimony Bonding in Crystal Sb2Te3, GeTe, and Ge2Sb2Te5

    Science.gov (United States)

    Bobela, David C.; Taylor, P. Craig

    2008-10-01

    As a starting point in understanding the magnetic resonance data for amorphous Ge2Sb2Te5, the prototypical phase change material, we have used 121Sb and 125Te nuclear magnetic resonance (NMR) to study crystalline Sb2Te3, GeTe, and Ge2Sb2Te5. The frequency space data are affected by a quadrupole (121Sb only) and chemical shift (121Sb and 125Te) interaction, which reflect the bonding asymmetries occurring around each nuclei. The 125Te data indicate there are two distinct Te sites in Sb2Te3 and one Te site in the GeTe, in agreement with the known crystal structures. The Ge2Sb2Te5125Te data are less well-resolved, which is probably a consequence of the random arrangement of Sb/Ge atoms around the Te sites. Despite the lack of resolution, these data do correspond to the spectral positions and breadths observed in Sb2Te3 and GeTe, which suggests that Ge2Sb2Te5 contains similar Te bonding structures. The 121Sb data in Sb2Te3 show that the Sb sites have an approximately axially symmetric bonding environment. The Sb data in Ge2Sb2Te5 reveal that the average bonding structure of Sb is very different from the Sb sites occurring in Sb2Te3.

  17. Polarity-dependent resistance switching in GeSbTe phase-change thin films: The importance of excess Sb in filament formation

    Science.gov (United States)

    Pandian, Ramanathaswamy; Kooi, Bart J.; Oosthoek, Jasper L. M.; van den Dool, Pim; Palasantzas, George; Pauza, Andrew

    2009-12-01

    We show that polarity-dependent resistance switching in GeSbTe thin films depends strongly on Sb composition by comparing current-voltage characteristics in Sb-excess Ge2Sb2+xTe5 and stoichiometric Ge2Sb2Te5 samples. This type of switching in Ge2Sb2+xTe5 films is reversible with both continuous and pulsed dc voltages less than 1.5 V. Low and high resistance states of this switching can be attributed to formation and rupture, respectively, of electrically conductive Sb-bridges between the Ge2Sb2Te5 crystals and electrodes through the resistive amorphous phase. The coexistence of polarity-dependent resistance switching with amorphous-crystalline phase-changes renders great opportunities to expand the applicability of GeSbTe films for data storage applications.

  18. Inversion of diffraction data for amorphous materials

    Science.gov (United States)

    Pandey, Anup; Biswas, Parthapratim; Drabold, D. A.

    2016-09-01

    The general and practical inversion of diffraction data-producing a computer model correctly representing the material explored-is an important unsolved problem for disordered materials. Such modeling should proceed by using our full knowledge base, both from experiment and theory. In this paper, we describe a robust method to jointly exploit the power of ab initio atomistic simulation along with the information carried by diffraction data. The method is applied to two very different systems: amorphous silicon and two compositions of a solid electrolyte memory material silver-doped GeSe3. The technique is easy to implement, is faster and yields results much improved over conventional simulation methods for the materials explored. By direct calculation, we show that the method works for both poor and excellent glass forming materials. It offers a means to add a priori information in first-principles modeling of materials, and represents a significant step toward the computational design of non-crystalline materials using accurate interatomic interactions and experimental information.

  19. Phase Transition Phenomena in Ultra-Thin Ge2Sb2Te5 Film

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ting; LIU Bo; SONG Zhi-Tang; LIU Wei-Li; FENG Song-Lin; CHEN Bomy

    2005-01-01

    @@ We observe reversible phase transition phenomena in proto-type chalcogenide random access memory (C-RAM)devices adopting ultra-thin (12nm) Ge2Sb3 Te5 thin film. In this kind of proto-type device, the ultra-thin amorphous Ge2Sb2 Te5 thin film undergoes a crystallization process when a voltage is applied. The polycrystalline Ge2Sb3 Te5 remain unchanged when the voltage is below 0.6 V. A higher power is needed if the transition from polycrystalline to amorphous is expected. The re-amorphization process can be realized by applying a voltage higher than 0.7 V. The threshold voltage Vth and threshold electric field Eth of the transition from the polycrystalline state to the amorphous state in this proto-type device are ~0.7 V and ~ 5 × 105 V/cm, respectively. The programming voltage is significantly reduced compared to the values of C-RAM devices adopting a 200-nm-thick Ge2Sb2 Te5 inset.

  20. Green laser crystallization of GeSi thin films and dopant activation

    NARCIS (Netherlands)

    Rangarajan, Balaji; Brunets, Ihor; Oesterlin, Peter

    2011-01-01

    Laser-crystallization of amorphous $Ge_{0.85}Si_{0.15}$ films is studied, using green laser scanning and preformed topography to steer the crystallization. Large crystals (8x2 $\\mu m^2$) are formed with location-controlled grain boundaries. The obtained films were characterized using Scanning Electr

  1. Sexuality and Sexual Dysfunctions in Bipolar Disorder

    Directory of Open Access Journals (Sweden)

    Zeynep Namli

    2016-12-01

    Full Text Available In the clinical course of bipolar disorder, there is a reduction in sexual will during depressive episodes and inappopriate sexual experiences and hypersexuality occurs during manic episodes. Up to now, studies focused on sexual side effects of drugs. Sexual violence, sexually transmitted diseases, contraception methods, unplanned pregnancies need to be assessed carefully in bipolar disorder patients. This review focused on sexuality and sexual dysfunctions in the course of bipolar disorder. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2016; 8(4.000: 309-320

  2. Interventions for Sleep Disturbance in Bipolar Disorder.

    Science.gov (United States)

    Harvey, Allison G; Kaplan, Katherine A; Soehner, Adriane M

    2015-03-01

    Bipolar disorder is a severe and chronic disorder, ranked in the top 10 leading causes of disability worldwide. Sleep disturbances are strongly coupled with interepisode dysfunction and symptom worsening in bipolar disorder. Experimental studies suggest that sleep deprivation can trigger manic relapse. There is evidence that sleep deprivation can have an adverse impact on emotion regulation the following day. The clinical management of the sleep disturbances experienced by bipolar patients, including insomnia, hypersomnia delayed sleep phase, and irregular sleep-wake schedule, may include medication approaches, psychological interventions, light therapies and sleep deprivation.

  3. Paired structures and bipolar knowledge representation

    DEFF Research Database (Denmark)

    Montero, Javier; Bustince, Humberto; Franco, Camilo

    In this strictly positional paper we propose a general approach to bipolar knowledge representation, where the meaning of concepts can be modelled by examining their decomposition into opposite and neutral categories. In particular, it is the semantic relationship between the opposite categories...... and at the same time the type of neutrality rising in between opposites. Based on this first level of bipolar knowledge representation, paired structures in fact offer the means to characterize a specific bipolar valuation scale depending on the meaning of the concept that has to be verified. In this sense...

  4. Fundamentals of amorphous solids structure and properties

    CERN Document Server

    Stachurski, Zbigniew H

    2014-01-01

    Long awaited, this textbook fills the gap for convincing concepts to describe amorphous solids. Adopting a unique approach, the author develops a framework that lays the foundations for a theory of amorphousness. He unravels the scientific mysteries surrounding the topic, replacing rather vague notions of amorphous materials as disordered crystalline solids with the well-founded concept of ideal amorphous solids. A classification of amorphous materials into inorganic glasses, organic glasses, glassy metallic alloys, and thin films sets the scene for the development of the model of ideal amorph

  5. Nanostructures having crystalline and amorphous phases

    Science.gov (United States)

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  6. Amorphization of Crystalline Water Ice

    CERN Document Server

    Zheng, Weijun; Kaiser, Ralf I

    2008-01-01

    We conducted a systematic experimental study to investigate the amorphization of crystalline ice by irradiation in the 10-50 K temperature range with 5 keV electrons at a dose of ~140 eV per molecule. We found that crystalline water ice can be converted partially to amorphous ice by electron irradiation. Our experiments showed that some of the 1.65-micrometer band survived the irradiation, to a degree that depends on the temperature, demonstrating that there is a balance between thermal recrystallization and irradiation-induced amorphization, with thermal recrystallizaton dominant at higher temperatures. At 50 K, recrystallization due to thermal effects is strong, and most of the crystalline ice survived. Temperatures of most known objects in the solar system, including Jovian satellites, Saturnian satellites, and Kuiper belt objects, are equal to or above 50 K, this might explain why water ice detected on those objects is mostly crystalline.

  7. Infrared transient grating measurements of the dynamics of hydrogen local mode vibrations in amorphous silicon-germanium

    NARCIS (Netherlands)

    Jobson, K.W.; Wells, J.P.R.; Schropp, R.E.I.; Vinh, N.Q.; Dijkhuis, J.I.

    2008-01-01

    We report on picosecond, time-resolved measurements of the vibrational relaxation and decay pathways of the Si–H and Ge–H stretching modes in hydrogenated amorphous silicon-germanium thin films (a-SiGe:H). It is demonstrated that the decay of both modes has a nonexponential shape, attributable to th

  8. Overview of patient care issues and treatment in bipolar spectrum and bipolar II disorder.

    Science.gov (United States)

    Calabrese, Joseph R

    2008-06-01

    Recent studies have reported lifetime prevalence estimates of 1.0% for bipolar I disorder, 1.1% for bipolar II disorder, and 2.4% to 4.7% for subthreshold bipolar disorder, illustrating the need for consensus definitions of bipolar spectrum disorders. These definitions will aid researchers in studying viable treatments options, as well as help clinicians in the differential diagnosis of patients. Broader definitions of bipolar spectrum disorders would also allow clinicians to more accurately diagnose patients, rather than placing them in the catchall category of bipolar disorder not otherwise specified. Bipolar symptoms that are currently labeled as subthreshold symptoms are becoming increasingly recognized as having relevant clinical implications. Despite diagnostic controversy, screening for the presence of mania in patients who present with depressive symptoms is a critical step in the appropriate treatment of bipolar spectrum disorders. Identifying the early onset of bipolar symptoms as manifested in prodromal disorders such as childhood major depressive disorder and attention-deficit/hyperactivity disorder is also important for possible early intervention and improved outcomes.

  9. Bipolar disorder and neurophysiologic mechanisms

    Directory of Open Access Journals (Sweden)

    Simon M McCrea

    2008-11-01

    Full Text Available Simon M McCreaDepartments of Neurology and Neuroophthalmology, University of British Columbia, 2550 Willow Street, Vancouver, British Columbia, Canada V5Z 3N9Abstract: Recent studies have suggested that some variants of bipolar disorder (BD may be due to hyperconnectivity between orbitofrontal (OFC and temporal pole (TP structures in the dominant hemisphere. Some initial MRI studies noticed that there were corpus callosum abnormalities within specific regional areas and it was hypothesized that developmentally this could result in functional or effective connectivity changes within the orbitofrontal-basal ganglia-thalamocortical circuits. Recent diffusion tensor imaging (DTI white matter fiber tractography studies may well be superior to region of interest (ROI DTI in understanding BD. A “ventral semantic stream” has been discovered connecting the TP and OFC through the uncinate and inferior longitudinal fasciculi and the elusive TP is known to be involved in theory of mind and complex narrative understanding tasks. The OFC is involved in abstract valuation in goal and sub-goal structures and the TP may be critical in binding semantic memory with person–emotion linkages associated with narrative. BD patients have relative attenuation of performance on visuoconstructional praxis consistent with an atypical localization of cognitive functions. Multiple lines of evidence suggest that some BD alleles are being selected for which could explain the enhanced creativity in higher-ability probands. Associations between ROI’s that are not normally connected could explain the higher incidence of artistic aptitude, writing ability, and scientific achievements among some mood disorder subjects.Keywords: bipolar disorder, diffusion tensor imaging, white matter tractography, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, mood dysphoria, creativity, ventral semantic stream, writing ability, artistic aptitude

  10. Miniature Bipolar Electrostatic Ion Thruster

    Science.gov (United States)

    Hartley, Frank T.

    2006-01-01

    The figure presents a concept of a bipolar miniature electrostatic ion thruster for maneuvering a small spacecraft. The ionization device in the proposed thruster would be a 0.1-micron-thick dielectric membrane with metal electrodes on both sides. Small conical holes would be micromachined through the membrane and electrodes. An electric potential of the order of a volt applied between the membrane electrodes would give rise to an electric field of the order of several mega-volts per meter in the submicron gap between the electrodes. An electric field of this magnitude would be sufficient to ionize all the molecules that enter the holes. In a thruster-based on this concept, one or more propellant gases would be introduced into such a membrane ionizer. Unlike in larger prior ion thrusters, all of the propellant molecules would be ionized. This thruster would be capable of bipolar operation. There would be two accelerator grids - one located forward and one located aft of the membrane ionizer. In one mode of operation, which one could denote the forward mode, positive ions leaving the ionizer on the backside would be accelerated to high momentum by an electric field between the ionizer and an accelerator grid. Electrons leaving the ionizer on the front side would be ejected into free space by a smaller accelerating field. The equality of the ion and electron currents would eliminate the need for an additional electron- or ion-emitting device to keep the spacecraft charge-neutral. In another mode of operation, which could denote the reverse mode, the polarities of the voltages applied to the accelerator grids and to the electrodes of the membrane ionizer would be the reverse of those of the forward mode. The reversal of electric fields would cause the ion and electrons to be ejected in the reverse of their forward mode directions, thereby giving rise to thrust in the direction opposite that of the forward mode.

  11. Structural, thermal, and photoacoustic study of nanocrystalline Cr{sub 3}Ge produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Prates, P. B.; Maliska, A. M.; Ferreira, A. S. [Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Poffo, C. M. [Universidade Federal de Santa Catarina, Campus de Araranguá, 88900-000 Araranguá, Santa Catarina (Brazil); Borges, Z. V. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Lima, J. C. de, E-mail: fsc1jcd@fisica.ufsc.br [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Biasi, R. S. de [Seção de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro (Brazil)

    2015-10-21

    A thermodynamic analysis of the Cr-Ge system suggested that it was possible to produce a nanostructured Cr{sub 3}Ge phase by mechanical alloying. The same analysis showed that, due to low activation energies, Cr-poor crystalline and/or amorphous alloy could also be formed. In fact, when the experiment was performed, Cr{sub 11}Ge{sub 19} and amorphous phases were present for small milling times. For milling times larger than 15 h these additional phases decomposed and only the nanostructured Cr{sub 3}Ge phase remained up to the highest milling time used (32 h). From the differential scanning calorimetry measurements, the Avrami exponent n was obtained, indicating that the nucleation and growth of the nanostructured Cr{sub 3}Ge phase may be restricted to one or two dimensions, where the Cr and Ge atoms diffuse along the surface and grain boundaries. In addition, contributions from three-dimensional diffusion with a constant nucleation rate may be present. The thermal diffusivity of the nanostructured Cr{sub 3}Ge phase was determined by photoacoustic absorption spectroscopy measurements.

  12. Gene environment interactions in bipolar disorder.

    Science.gov (United States)

    Pregelj, Peter

    2011-09-01

    It has been estimated that the heritable component of bipolar disorder ranges between 80 and 90%. However, even genome-wide association studies explain only a fraction of phenotypic variability not resolving the problem of "lost heritability". Although direct evidence for epigenetic dysfunction in bipolar disorder is still limited, methodological technologies in epigenomic profiling have advanced, offering even single cell analysing and resolving the problem of cell heterogeneity in epigenetics research. Gene overlapping with other mental disorders represents another problem in identifying potential susceptibility genes in bipolar disorder. Better understanding of the interplay between multiple environmental and genetic factors involved in the patogenesis of bipolar disorder could provide relevant information for treatment of patients with this complex disorder. Future studies on the role of these factors in psychopathological conditions, subphenotypes and endophenotypes may greatly benefit by using more precise clinical data and a combined approach with multiple research tools incorporated into a single study.

  13. Are rates of pediatric bipolar disorder increasing?

    DEFF Research Database (Denmark)

    Kessing, Lars Vedel; Vradi, Eleni; Andersen, Per Kragh

    2014-01-01

    Studies from the USA suggest that rates of pediatric bipolar disorder have increased since the mid-90s, but no study outside the USA has been published on the rates of pediatric bipolar disorder. Further, it is unclear whether an increase in rates reflects a true increase in the illness or more...... diagnostic attention. Using nationwide registers of all inpatients and outpatients contacts to all psychiatric hospitals in Denmark, we investigated (1) gender-specific rates of incident pediatric mania/bipolar disorder during a period from 1995 to 2012, (2) whether age and other characteristics...... for pediatric mania/bipolar disorder changed during the calendar period (1995 to 2003 versus 2004 to 2012), and (3) whether the diagnosis is more often made at first psychiatric contact in recent time compared to earlier according to gender. Totally, 346 patients got a main diagnosis of a manic episode (F30...

  14. Climatic factors and bipolar affective disorder

    DEFF Research Database (Denmark)

    Christensen, Ellen Margrethe; Larsen, Jens Knud; Gjerris, Annette

    2008-01-01

    In bipolar disorder, the factors provoking a new episode are unknown. As a seasonal variation has been noticed, it has been suggested that weather conditions may play a role. The aim of the study was to elucidate whether meteorological parameters influence the development of new bipolar phases....... A group of patients with at least three previous hospitalizations for bipolar disorder was examined every 3 months for up to 3 years. At each examination an evaluation of the affective phase was made according to the Hamilton Depression Scale (HAM-D(17)), and the Bech-Rafaelsen Mania Rating Scale (MAS......). In the same period, daily recordings from the Danish Meteorological Institute were received. We found no correlations between onset of bipolar episodes [defined as MAS score of 11 or more (mania) and as HAM-D(17) score of 12 or more (depression)] and any meteorological parameters. We found a statistical...

  15. Examination of the temperature dependent electronic behavior of GeTe for switching applications

    Science.gov (United States)

    Champlain, James G.; Ruppalt, Laura B.; Guyette, Andrew C.; El-Hinnawy, Nabil; Borodulin, Pavel; Jones, Evan; Young, Robert M.; Nichols, Doyle

    2016-06-01

    The DC and RF electronic behaviors of GeTe-based phase change material switches as a function of temperature, from 25 K to 375 K, have been examined. In its polycrystalline (ON) state, GeTe behaved as a degenerate p-type semiconductor, exhibiting metal-like temperature dependence in the DC regime. This was consistent with the polycrystalline (ON) state RF performance of the switch, which exhibited low resistance S-parameter characteristics. In its amorphous (OFF) state, the GeTe presented significantly greater DC resistance that varied considerably with bias and temperature. At low biases (presence of two regions of localized traps within the bandgap of the amorphous GeTe, located at approximately 0.26-0.27 eV and 0.56-0.57 eV from the valence band. Unlike the polycrystalline state, the high resistance DC behavior of amorphous GeTe does not translate to the RF switch performance; instead, a parasitic capacitance associated with the RF switch geometry dominates OFF state RF transmission.

  16. Atomic-scale quantification of interdiffusion and dopant localization in GeSbTe-based memory devices

    Science.gov (United States)

    Chae, B.-G.; Seol, J.-B.; Song, J.-H.; Jung, W.-Y.; Hwang, H.; Park, C.-G.

    2016-09-01

    Fabrication of phase-change memory devices at modest or ambient temperatures leads to nanoscale compositional variations in phase-transition layers, where amorphous-polycrystalline phase change takes place via electrical switching, and can alter the device's performances. Here, by transmission electron microscopy and atom probe tomography, we address that thermal annealing at 400 °C for 20 min induces an elemental interdiffusion in the devices consisting of TiN (top electrode), carbon-doped GeSbTe (phase-transition layer), and TiSiN (bottom heater). With respect to the employed annealing process, the Ge atoms of GeSbTe layer have diffused into TiSiN layer at a given sample volume, while the Ti atoms of TiSiN layer into GeSbTe layer. Furthermore, non-random nature of dopant distribution in the GeSbTe materials leads to a Ti-localization including dopants at the GeSbTe/TiSiN interfaces. Our findings have two important implications: First, the annealing-driven interdiffusion of Ge and Ti is a predominant mechanism responsible for nanoscale compositional variations in GeSbTe layer; second, such an interdiffusion and the resultant dopant localization play a crucial role on the driving force for amorphous-polycrystalline transition of GeSbTe-based memory devices.

  17. O transtorno bipolar na mulher Bipolar disorder in women

    Directory of Open Access Journals (Sweden)

    Alexandro de Borja Gonçalves Guerra

    2005-01-01

    Full Text Available Diferenças sexuais, descritas em vários transtornos psiquiátricos, também parecem estar presentes no transtorno afetivo bipolar (TAB. A prevalência do TAB tipo I se distribui igualmente entre mulheres e homens. Mulheres parecem estar sujeitas a um risco maior de ciclagem rápida e mania mista, condições que fariam do TAB um transtorno com curso mais prejudicial no sexo feminino. Uma diátese depressiva mais marcante, uso excessivo de antidepressivos e diferenças hormonais surgem como hipóteses para explicar essas diferenças fenomenológicas, apesar das quais, mulheres e homens parecem responder igualmente ao tratamento medicamentoso. A indicação de anticonvulsivantes como primeira escolha em mulheres é controversa, a não ser para o tratamento da mania mista e, talvez, da ciclagem rápida. O tratamento do TAB na gravidez deve levar em conta tanto os riscos de exposição aos medicamentos quanto à doença materna. A profilaxia do TAB no puerpério está fortemente indicada em decorrência do grande risco de recorrência da doença nesse período. Embora, de modo geral, as medicações psicotrópicas estejam contra-indicadas durante a amamentação, entre os estabilizadores do humor, a carbamazepina e o valproato são mais seguros do que o lítio. Mais estudos são necessários para a confirmação das diferenças de curso do TAB entre mulheres e homens e a investigação de possíveis diferenças na efetividade dos tratamentos.Gender differences, described in several psychiatric disorders, seem to be also present in bipolar disorder (BD. The prevalence of bipolar I disorder is equally distributed between women and men. Women seem to be at higher risk for rapid cycling and mixed mania, conditions that could make BD a disorder with a more severe course in the female sex. A marked depressive diathesis among women, greatest use of antidepressants and hormonal differences have been mentioned as hypotheses to explain these

  18. Psychosis Endophenotypes in Schizophrenia and Bipolar Disorder

    OpenAIRE

    Thaker, Gunvant

    2008-01-01

    Recent studies provide considerable evidence that schizophrenia and bipolar disorder may share overlapping etiologic determinants. Identifying disease-related genetic effects is a major focus in schizophrenia and bipolar disorder research, with implications for clarifying diagnosis and developing specific treatments for various impairments in these 2 disorders. Efforts have been multifaceted, with the ultimate goal of describing causal paths from specific genetic variants, to changes in neuro...

  19. Heritability of bipolar affective disorder: Family study

    OpenAIRE

    Obradović Tanja; Veličković Ružica; Timotijević Ivana; Anđelković Marko

    2011-01-01

    Background/Aim. Bipolar affective disorder is mental disorder with polygenic type of heredity. Heritability - relation between genetic and environmental variance is used to estimate the level of influence of genetic variance to phenotype variance. Study results show decreasing trend in the value of heritability of bipolar affective disorder, thus indicating that this disorder is a complex behavioral threshold characteristic. Therefore, the aim of this study was to estimate the contribut...

  20. Very Large Arrays of Bipolar Electrodes

    Science.gov (United States)

    2013-01-01

    Determination of Percent Hemoglobin A1c Using a Potentiometric Method, Analytical Chemistry, (02 2013): 0. doi: 10.1021/ac3032228 05/30/2013 13.00 Francois...Chemiluminescence (ECL) Emission at Bipolar Electrodes, Analytical Chemistry, (08 2009): 6218. doi: 10.1021/ac900744p 07/13/2012 1.00 Robbyn K...Anand, Stephen E. Fosdick, Ioana Dumitrescu, Richard M. Crooks. Pressure-Driven Bipolar Electrochemistry , Journal of the American Chemical Society

  1. Bipolar transistor in VESTIC technology: prototype

    Science.gov (United States)

    Mierzwiński, Piotr; Kuźmicz, Wiesław; Domański, Krzysztof; Tomaszewski, Daniel; Głuszko, Grzegorz

    2016-12-01

    VESTIC technology is an alternative for traditional CMOS technology. This paper presents first measurement data of prototypes of VES-BJT: bipolar transistors in VESTIC technology. The VES-BJT is a bipolar transistor on the SOI substrate with symmetric lateral structure and both emitter and collector made of polysilicon. The results indicate that VES-BJT can be a device with useful characteristics. Therefore, VESTIC technology has the potential to become a new BiCMOS-type technology with some unique properties.

  2. Structure and Spatial Distribution of Ge Nanocrystals Subjected to Fast Neutron Irradiation

    Directory of Open Access Journals (Sweden)

    Alexander N. Ionov

    2011-07-01

    Full Text Available The influence of fast neutron irradiation on the structure and spatial distribution of Ge nanocrystals (NC embedded in an amorphous SiO2 matrix has been studied. The investigation was conducted by means of laser Raman Scattering (RS, High Resolution Transmission Electron Microscopy (HR-TEM and X-ray photoelectron spectroscopy (XPS. The irradiation of Ge- NC samples by a high dose of fast neutrons lead to a partial destruction of the nanocrystals. Full reconstruction of crystallinity was achieved after annealing the radiation damage at 8000C, which resulted in full restoration of the RS spectrum. HR-TEM images show, however, that the spatial distributions of Ge-NC changed as a result of irradiation and annealing. A sharp decrease in NC distribution towards the SiO2 surface has been observed. This was accompanied by XPS detection of Ge oxides and elemental Ge within both the surface and subsurface region.

  3. Transfer-free synthesis of highly ordered Ge nanowire arrays on glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, M.; Toko, K., E-mail: toko@bk.tsukuba.ac.jp; Suemasu, T. [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Jevasuwan, W.; Fukata, N. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Saitoh, N.; Yoshizawa, N. [Electron Microscope Facility, TIA, AIST, 16-1 Onogawa, Tsukuba 305-8569 (Japan)

    2015-09-28

    Vertically aligned Ge nanowires (NWs) are directly synthesized on glass via vapor-liquid-solid (VLS) growth using chemical-vapor deposition. The use of the (111)-oriented Ge seed layer, formed by metal-induced crystallization at 325 °C, dramatically improved the density, uniformity, and crystal quality of Ge NWs. In particular, the VLS growth at 400 °C allowed us to simultaneously achieve the ordered morphology and high crystal quality of the Ge NW array. Transmission electron microscopy demonstrated that the resulting Ge NWs had no dislocations or stacking faults. Production of high-quality NW arrays on amorphous insulators will promote the widespread application of nanoscale devices.

  4. Effect of nitrogen doping on the thermal conductivity of GeTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Fallica, Roberto; Longo, Massimo; Wiemer, Claudia [Laboratorio MDM, IMM-CNR, Agrate Brianza (Italy); Varesi, Enrico; Fumagalli, Luca; Spadoni, Simona [Micron Semiconductor Italia, Agrate Brianza (Italy)

    2013-12-15

    The 3{omega} method was employed to determine the effect of nitrogen doping (5 at.%) on the thermal conductivity of sputtered thin films of stoichiometric GeTe (a material of interest for phase change memories). It was found that nitrogen doping has a detrimental effect on the thermal conductivity of GeTe in both phases, but less markedly in the amorphous (-25%) than in the crystalline one (-40%). On the opposite, no effect could be detected on the measured thermal boundary resistance between these films and SiO{sub 2}, within the experimental error. Our results agree with those obtained by molecular dynamic simulation of amorphous GeTe. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Amorphous titanium-oxide supercapacitors

    Science.gov (United States)

    Fukuhara, Mikio; Kuroda, Tomoyuki; Hasegawa, Fumihiko

    2016-10-01

    The electric capacitance of an amorphous TiO2-x surface increases proportionally to the negative sixth power of the convex diameter d. This occurs because of the van der Waals attraction on the amorphous surface of up to 7 mF/cm2, accompanied by extreme enhanced electron trapping resulting from both the quantum-size effect and an offset effect from positive charges at oxygen-vacancy sites. Here we show that a supercapacitor, constructed with a distributed constant-equipment circuit of large resistance and small capacitance on the amorphous TiO2-x surface, illuminated a red LED for 37 ms after it was charged with 1 mA at 10 V. The fabricated device showed no dielectric breakdown up to 1,100 V. Based on this approach, further advances in the development of amorphous titanium-dioxide supercapacitors might be attained by integrating oxide ribbons with a micro-electro mechanical system.

  6. The role of sleep in bipolar disorder

    Directory of Open Access Journals (Sweden)

    Gold AK

    2016-06-01

    Full Text Available Alexandra K Gold,1 Louisa G Sylvia,1,2 1Department of Psychiatry, Massachusetts General Hospital, 2Harvard Medical School, Boston, MA, USA Abstract: Bipolar disorder is a serious mental illness characterized by alternating periods of elevated and depressed mood. Sleep disturbances in bipolar disorder are present during all stages of the condition and exert a negative impact on overall course, quality of life, and treatment outcomes. We examine the partnership between circadian system (process C functioning and sleep–wake homeostasis (process S on optimal sleep functioning and explore the role of disruptions in both systems on sleep disturbances in bipolar disorder. A convergence of evidence suggests that sleep problems in bipolar disorder result from dysregulation across both process C and process S systems. Biomarkers of depressive episodes include heightened fragmentation of rapid eye movement (REM sleep, reduced REM latency, increased REM density, and a greater percentage of awakenings, while biomarkers of manic episodes include reduced REM latency, greater percentage of stage I sleep, increased REM density, discontinuous sleep patterns, shortened total sleep time, and a greater time awake in bed. These findings highlight the importance of targeting novel treatments for sleep disturbance in bipolar disorder. Keywords: bipolar disorder, circadian rhythms, sleep–wake homeostasis

  7. Rumination in bipolar disorder: evidence for an unquiet mind

    Directory of Open Access Journals (Sweden)

    Ghaznavi Sharmin

    2012-01-01

    Full Text Available Abstract Depression in bipolar disorder has long been thought to be a state characterized by mental inactivity. However, recent research demonstrates that patients with bipolar disorder engage in rumination, a form of self-focused repetitive cognitive activity, in depressed as well as in manic states. While rumination has long been associated with depressed states in major depressive disorder, the finding that patients with bipolar disorder ruminate in manic states is unique to bipolar disorder and challenges explanations put forward for why people ruminate. We review the research on rumination in bipolar disorder and propose that rumination in bipolar disorder, in both manic and depressed states, reflects executive dysfunction. We also review the neurobiology of bipolar disorder and recent neuroimaging studies of rumination, which is consistent with our hypothesis that the tendency to ruminate reflects executive dysfunction in bipolar disorder. Finally, we relate the neurobiology of rumination to the neurobiology of emotion regulation, which is disrupted in bipolar disorder.

  8. Ferromagnetism modulation by phase change in Mn-doped GeTe chalcogenide magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Adam, Adam Abdalla Elbashir [Huazhong University of Science and Technology, School of Optical and Electronic Information, Wuhan (China); Wuhan National Laboratory for Optoelectronics, Wuhan (China); Alneelain University, Faculty of Science and Technology, Khartoum (Sudan); Cheng, Xiaomin; Guan, Xiawei; Miao, Xiangshui [Huazhong University of Science and Technology, School of Optical and Electronic Information, Wuhan (China); Wuhan National Laboratory for Optoelectronics, Wuhan (China)

    2014-12-15

    In this work, an effective method to modulate the ferromagnetic properties of Mn-doped GeTe chalcogenide-based phase change materials is presented. The microstructure of the phase change magnetic material Ge{sub 1-x} Mn{sub x} Te thin films was studied. The X-ray diffraction results demonstrate that the as-deposited films are amorphous, and the crystalline films are formed after annealing at 350 C for 10 min. Crystallographic structure investigation shows the existence of some secondary magnetic phases. The lattice parameters of Ge{sub 1-x} Mn{sub x} Te (x = 0.04, 0.12 and 0.15) thin films are found to be slightly different with changes of Mn compositions. The structural analysis clearly indicates that all the films have a stable rhombohedral face-centered cubic polycrystalline structure. The magnetic properties of the amorphous and crystalline Ge{sub 0.96}Mn{sub 0.04}Te were investigated. The measurements of magnetization (M) as a function of the magnetic field (H) show that both amorphous and crystalline phases of Ge{sub 0.96}Mn{sub 0.04}Te thin film are ferromagnetic and there is drastic variation between amorphous and crystalline states. The temperature (T) dependence of magnetizations at zero field cooling (ZFC) and field cooling (FC) conditions of the crystalline Ge{sub 0.96}Mn{sub 0.04}Te thin film under different applied magnetic fields were performed. The measured data at 100 and 300 Oe applied magnetic fields show large bifurcations in the ZFC and FC curves while on the 5,000 Oe magnetic field there is no deviation. (orig.)

  9. Subcortical Gray Matter Volume Abnormalities in Healthy Bipolar Offspring: Potential Neuroanatomical Risk Marker for Bipolar Disorder?

    Science.gov (United States)

    Ladouceur, Cecile D.; Almeida, Jorge R. C.; Birmaher, Boris; Axelson, David A.; Nau, Sharon; Kalas, Catherine; Monk, Kelly; Kupfer, David J.; Phillips, Mary L.

    2008-01-01

    A study is conducted to examine the extent to which bipolar disorder (BD) is associated with gray matter volume abnormalities in brain regions in healthy bipolar offspring relative to age-matched controls. Results show increased gray matter volume in the parahippocampus/hippocampus in healthy offspring at genetic risk for BD.

  10. Clinical, Demographic, and Familial Correlates of Bipolar Spectrum Disorders among Offspring of Parents with Bipolar Disorder

    Science.gov (United States)

    Goldstein, Benjamin I.; Shamseddeen, Wael; Axelson, David A.; Kalas, Cathy; Monk, Kelly; Brent, David A.; Kupfer, David J.; Birmaher, Boris

    2010-01-01

    Objective: Despite increased risk, most offspring of parents with bipolar disorder (BP) do not manifest BP. The identification of risk factors for BP among offspring could improve preventive and treatment strategies. We examined this topic in the Pittsburgh Bipolar Offspring Study (BIOS). Method: Subjects included 388 offspring, ages 7-17 years,…

  11. Terapia comportamental cognitiva para pessoas com transtorno bipolar Cognitive behavioral therapy for bipolar disorders

    Directory of Open Access Journals (Sweden)

    Francisco Lotufo Neto

    2004-10-01

    Full Text Available Descrição dos objetivos e principais técnicas da terapia comportamental cognitiva usadas para a psicoterapia das pessoas com transtorno bipolar.Objectives and main techniques of cognitive behavior therapy for the treatment of bipolar disorder patients are described.

  12. Structural study of Ge/GaAs thin films

    Science.gov (United States)

    Lazarov, V. K.; Lari, L.; Lytvyn, P. M.; Kholevchuk, V. V.; Mitin, V. F.

    2012-07-01

    Ge/GaAs heterostructure research is largely motivated by the application of this material in solar cells, metal-oxide-semiconductor field-effect transistors, mm-wave mixer diodes, temperature sensors and photodetectors. Therefore, understanding of how the properties of Ge/GaAs heterostructure depend on its preparation (growth) is of importance for various high-efficiency devices. In this work, by using thermal Ge evaporation on GaAs(100), we studied structural properties of these films as a function of the deposition rate. Film grains size and morphology show strong dependence of the deposition rate. Low deposition rates results in films with large crystal grains and rough surface. At high deposition rates films become flatter and their crystal grains size decreases, while at very high deposition rates films become amorphous. Cross-sectional TEM of the films show that the Ge films are granular single crystal epitaxially grown on GaAs. The Ge/GaAs interface is atomically abrupt and free from misfit dislocations. Stacking faults along the [111] directions that originate at the interface were also observed. Finally by using the Kelvin probe microscopy we show that work function changes are related to the grain structure of the film.

  13. Ion-beam induced structure modifications in amorphous germanium; Ionenstrahlinduzierte Strukturmodifikationen in amorphem Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Steinbach, Tobias

    2012-05-03

    Object of the present thesis was the systematic study of ion-beam induced structure modifications in amorphous germanium (a-Ge) layers due to low- (LEI) and high-energetic (SHI) ion irradiation. The LEI irradiation of crystalline Ge (c-Ge) effects because the dominating nuclear scattering of the ions on the solid-state atoms the formation of a homogeneous a-Ge Layer. Directly on the surface for fluences of two orders of magnitude above the amorphization fluence the formation of stable cavities independently on the irradiation conditions was observed. For the first time for the ion-beam induced cavity formation respectively for the steady expansion of the porous layer forming with growing fluence a linear dependence on the energy {epsilon}{sub n} deposed in nuclear processes was detected. Furthermore the formation of buried cavities was observed, which shows a dependence on the type of ions. While in the c-Ge samples in the range of the high electronic energy deposition no radiation defects, cavities, or plastic deformations were observed, the high electronic energy transfer in the 3.1 {mu}m thick pre-amorphized a-Ge surface layers leads to the formation of randomly distributed cavities. Basing on the linear connection between cavity-induced vertical volume expansion and the fluence determined for different energy transfers for the first time a material-specific threshold value of {epsilon}{sub e}{sup HRF}=(10.5{+-}1.0) kev nm{sup -1} was determined, above which the ion-beam induced cavity formation in a-Ge sets on. The anisotropic plastic deformation of th a-Ge layer superposed at inclined SHI irradiation on the cavity formation was very well described by an equation derived from the viscoelastic Maxwell model, but modified under regardment of the experimental results. The positive deformation yields determined thereby exhibit above a threshold value for the ion-beam induced plastic deformation {epsilon}{sub e}{sup S{sub a}}=(12{+-}2) keV nm{sup -1} for the first

  14. Role of mechanical stress in the resistance drift of Ge2Sb2Te5 films and phase change memories

    Science.gov (United States)

    Rizzi, M.; Spessot, A.; Fantini, P.; Ielmini, D.

    2011-11-01

    In a phase change memory (PCM), the device resistance increases slowly with time after the formation of the amorphous phase, thus affecting the stability of stored data. This work investigates the resistance drift in thin films of amorphous Ge2Sb2Te5 and in PCMs, demonstrating a common kinetic of drift in stressed/unstressed films and in the nanometer-size active volume of a PCM with different stress levels developed via stressor layers. It is concluded that stress is not the root cause of PCM drift, which is instead attributed to intrinsic structural relaxation due to the disordered, metastable nature of the amorphous chalcogenide phase.

  15. Processamento cognitivo "Teoria da Mente" no transtorno bipolar Cognitive "Theory of Mind" processing in bipolar disorder

    Directory of Open Access Journals (Sweden)

    Hélio Anderson Tonelli

    2009-12-01

    Full Text Available OBJETIVO: O transtorno afetivo bipolar está associado ao comprometimento funcional persistente. Apesar de muitas pesquisas demonstrarem que bipolares podem apresentar déficits cognitivos, um número menor de trabalhos avaliou o papel de prejuízos no processamento cognitivo social, a Teoria da Mente (relacionado à capacidade de inferir estados mentais, no aparecimento de sintomas e complicações sociais em bipolares. O objetivo deste trabalho é o de revisar sistemática e criticamente a literatura sobre possíveis alterações do processamento Teoria da Mente no transtorno afetivo bipolar. MÉTODO: Foi realizada uma busca na base de dados Medline por trabalhos publicados em língua inglesa, alemã, espanhola ou portuguesa nos últimos 20 anos, utilizando a frase de busca "Bipolar Disorder"[Mesh] AND "Theory of Mind". Foram procurados por estudos clínicos envolvendo indivíduos bipolares e que empregaram uma ou mais tarefas cognitivas desenvolvidas para a avaliação de habilidades Teoria da Mente. Foram excluídos os relatos de caso e cartas ao editor. A busca inicial resultou em cinco artigos, sendo selecionados quatro. Outros quatro foram também selecionados a partir da leitura dos artigos acima. DISCUSSÃO: Os artigos selecionados avaliaram populações de bipolares adultos e pediátricos, incluindo indivíduos eutímicos, maníacos e deprimidos. A maioria dos trabalhos avaliados sugere que existam prejuízos no processamento Teoria da Mente em portadores de transtorno afetivo bipolar e que estes podem estar por trás dos sintomas e dos déficits funcionais do transtorno afetivo bipolar. CONCLUSÃO: Pesquisas futuras a respeito do tema em questão poderão esclarecer muito acerca do papel das alterações sociocognitivas no surgimento dos sintomas do transtorno afetivo bipolar, bem como ajudar no desenvolvimento de estratégias preventivas e terapêuticas do mesmo.OBJECTIVE: Bipolar disorder is associated to persistent functional

  16. Flexible amorphous metal films with high stability

    Science.gov (United States)

    Liu, M.; Cao, C. R.; Lu, Y. M.; Wang, W. H.; Bai, H. Y.

    2017-01-01

    We report the formation of amorphous Cu50Zr50 films with a large-area of more than 100 cm2. The films were fabricated by ion beam assisted deposition with a slow deposition rate at moderate temperature. The amorphous films have markedly enhanced thermal stability, excellent flexibility, and high reflectivity with atomic level smoothness. The multifunctional properties of the amorphous films are favorites in the promising applications of smart skin or wearable devices. The method of preparing highly stable amorphous metal films by tuning the deposition rate instead of deposition temperature could pave a way for exploring amorphous metal films with unique properties.

  17. Photoluminescence and electroluminescence from Ge/strained GeSn/Ge quantum wells

    Science.gov (United States)

    Lin, Chung-Yi; Huang, Chih-Hsiung; Huang, Shih-Hsien; Chang, Chih-Chiang; Liu, C. W.; Huang, Yi-Chiau; Chung, Hua; Chang, Chorng-Ping

    2016-08-01

    Ge/strained GeSn/Ge quantum wells are grown on a 300 mm Si substrate by chemical vapor deposition. The direct bandgap emission from strained GeSn is observed in the photoluminescence spectra and is enhanced by Al2O3/SiO2 passivation due to the field effect. The electroluminescence of the direct bandgap emission of strained GeSn is also observed from the Ni/Al2O3/GeSn metal-insulator-semiconductor tunneling diodes. Electroluminescence is a good indicator of GeSn material quality, since defects in GeSn layers degrade the electroluminescence intensity significantly. At the accumulation bias, the holes in the Ni gate electrode tunnel to the strained n-type GeSn layer through the ultrathin Al2O3 and recombine radiatively with electrons. The emission wavelength of photoluminescence and electroluminescence can be tuned by the Sn content.

  18. Low Specific Contact Resistivity to n-Ge and Well-Behaved Ge n+/p Diode Achieved by Implantation and Excimer Laser Annealing

    Science.gov (United States)

    Wang, Chen; Li, Cheng; Huang, Shihao; Lu, Weifang; Yan, Guangming; Lin, Guangyang; Wei, Jiangbin; Huang, Wei; Lai, Hongkai; Chen, Songyan

    2013-10-01

    Excimer laser annealing of phosphorus-implanted p-type germanium substrate with various laser energy densities for n+/p junction were investigated. The effects of laser energy density on the redistribution of dopant, surface morphology, and recrystallization of the amorphous Ge induced by ion implantation were characterized. A low specific contact resistivity of 1.61×10-6 Ω·cm2 was achieved from Al/n-Ge ohmic contact, in which phosphorus-implanted Ge was annealed at a laser energy density of 250 mJ/cm2, tailoring a small phosphorus diffusion length, high activation level, and low dopant loss. A well-behaved Ge n+/p diode with a rectification ratio up to 1.99×105 was demonstrated.

  19. Big data for bipolar disorder.

    Science.gov (United States)

    Monteith, Scott; Glenn, Tasha; Geddes, John; Whybrow, Peter C; Bauer, Michael

    2016-12-01

    The delivery of psychiatric care is changing with a new emphasis on integrated care, preventative measures, population health, and the biological basis of disease. Fundamental to this transformation are big data and advances in the ability to analyze these data. The impact of big data on the routine treatment of bipolar disorder today and in the near future is discussed, with examples that relate to health policy, the discovery of new associations, and the study of rare events. The primary sources of big data today are electronic medical records (EMR), claims, and registry data from providers and payers. In the near future, data created by patients from active monitoring, passive monitoring of Internet and smartphone activities, and from sensors may be integrated with the EMR. Diverse data sources from outside of medicine, such as government financial data, will be linked for research. Over the long term, genetic and imaging data will be integrated with the EMR, and there will be more emphasis on predictive models. Many technical challenges remain when analyzing big data that relates to size, heterogeneity, complexity, and unstructured text data in the EMR. Human judgement and subject matter expertise are critical parts of big data analysis, and the active participation of psychiatrists is needed throughout the analytical process.

  20. Bipolar disorder and neurophysiologic mechanisms.

    Science.gov (United States)

    McCrea, Simon M

    2008-12-01

    Recent studies have suggested that some variants of bipolar disorder (BD) may be due to hyperconnectivity between orbitofrontal (OFC) and temporal pole (TP) structures in the dominant hemisphere. Some initial MRI studies noticed that there were corpus callosum abnormalities within specific regional areas and it was hypothesized that developmentally this could result in functional or effective connectivity changes within the orbitofrontal-basal ganglia-thalamocortical circuits. Recent diffusion tensor imaging (DTI) white matter fiber tractography studies may well be superior to region of interest (ROI) DTI in understanding BD. A "ventral semantic stream" has been discovered connecting the TP and OFC through the uncinate and inferior longitudinal fasciculi and the elusive TP is known to be involved in theory of mind and complex narrative understanding tasks. The OFC is involved in abstract valuation in goal and sub-goal structures and the TP may be critical in binding semantic memory with person-emotion linkages associated with narrative. BD patients have relative attenuation of performance on visuoconstructional praxis consistent with an atypical localization of cognitive functions. Multiple lines of evidence suggest that some BD alleles are being selected for which could explain the enhanced creativity in higher-ability probands. Associations between ROI's that are not normally connected could explain the higher incidence of artistic aptitude, writing ability, and scientific achievements among some mood disorder subjects.

  1. Nanoscale manipulation of Ge nanowires by ion hammering

    Energy Technology Data Exchange (ETDEWEB)

    Picraux, Samuel T [Los Alamos National Laboratory; Romano, Lucia [UNIV OF FLORIDA; Rudawski, Nicholas G [UNIV OF FLORIDA; Holzworth, Monta R [UNIV OF FLORIDA; Jones, Kevin S [UNIV OF FLORIDA; Choi, S G [NREL

    2009-01-01

    Nanowires generated considerable interest as nanoscale interconnects and as active components of both electronic and electromechanical devices. However, in many cases, manipulation and modification of nanowires are required to realize their full potential. It is essential, for instance, to control the orientation and positioning of nanowires in some specific applications. This work demonstrates a simple method to reversibly control the shape and the orientation of Ge nanowires by using ion beams. Initially, crystalline nanowires were partially amorphized by 30 keY Ga+-implantation. After amorphization, viscous flow and plastic deformation occurred due to the ion hammering effect, causing the nanowires to bend toward the beam direction. The bending was reversed multiple times by ion-implanting the opposite side of the nanowires, resulting in straightening of the nanowires and subsequent bending in the opposite direction. This ion hammering effect demonstrates the detailed manipulation of nanoscale structures is possible through the use of ion irradiation.

  2. Structural, electric and kinetic parameters of ternary alloys of GeSbTe

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Sanchez, E. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Libramiento Norponiente 2000, Ap. Postal 13, Juriquilla, Queretaro, C. P. 76230, (Mexico)]. E-mail: m6007@ciateq.net.mx; Prokhorov, E.F. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Libramiento Norponiente 2000, Ap. Postal 13, Juriquilla, Queretaro, C. P. 76230, (Mexico); Gonzalez-Hernandez, J. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Libramiento Norponiente 2000, Ap. Postal 13, Juriquilla, Queretaro, C. P. 76230, (Mexico); Mendoza-Galvan, A. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Libramiento Norponiente 2000, Ap. Postal 13, Juriquilla, Queretaro, C. P. 76230, (Mexico)

    2005-01-03

    Thin amorphous films of GeSbTe have been widely employed in the technology used for phase change optical memory or compact disks. In this article, we report on measurements of resistance, transmittance, and X-ray diffraction in thin films with stoichiometric compositions of Ge{sub 1}Sb{sub 4}Te{sub 7}, Ge{sub 1}Sb{sub 2}Te{sub 4}, Ge{sub 2}Sb{sub 2}Te{sub 5}, and Ge{sub 4}Sb{sub 1}Te{sub 5.} The resistivity, lattice constant, and the temperature at which transformation from the amorphous phase to the cubic crystalline structure occurs were calculated for each stoichiometric composition, and the energy activation was determined, applying Kissinger's model. It was found that the Ge{sub 4}Sb{sub 1}Te{sub 5} composition has the highest crystallization temperature (425 K), the highest resistivity (0.178 {omega} cm), the greatest E{sub a} (3.09 eV), and the lowest lattice constant (a=5.975 A) in the cubic phase at 170 deg C.

  3. Behaviors of Zn2GeO4 under high pressure and high temperature

    Science.gov (United States)

    Shu-Wen, Yang; Fang, Peng; Wen-Tao, Li; Qi-Wei, Hu; Xiao-Zhi, Yan; Li, Lei; Xiao-Dong, Li; Duan-Wei, He

    2016-07-01

    The structural stability of Zn2GeO4 was investigated by in-situ synchrotron radiation angle dispersive x-ray diffraction. The pressure-induced amorphization is observed up to 10 GPa at room temperature. The high-pressure and high-temperature sintering experiments and the Raman spectrum measurement firstly were performed to suggest that the amorphization is caused by insufficient thermal energy and tilting Zn-O-Ge and Ge-O-Ge bond angles with increasing pressure, respectively. The calculated bulk modulus of Zn2GeO4 is 117.8 GPa from the pressure-volume data. In general, insights into the mechanical behavior and structure evolution of Zn2GeO4 will shed light on the micro-mechanism of the materials variation under high pressure and high temperature. Project supported by the Joint Fund of the National Natural Science Foundation of China and Chinese Academy of Sciences (Grant No. U1332104).

  4. Structure and electronic properties features of amorphous chalhogenide semiconductor films prepared by ion-plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Korobova, N., E-mail: korobova3@mail.ru; Timoshenkov, S. [Department of Microelectronics, National Research University of Electronic Technology (MIET), Zelenograd (Russian Federation); Almasov, N.; Prikhodko, O. [al-Farabi Kazakh National University, Almaty (Kazakhstan); Tsendin, K. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

    2014-10-21

    Structure of amorphous chalcogenide semiconductor glassy As-S-Se films, obtained by high-frequency (HF) ion-plasma sputtering has been investigated. It was shown that the length of the atomic structure medium order and local structure were different from the films obtained by thermal vacuum evaporation. Temperature dependence of dark conductivity, as well as the dependence of the spectral transmittance has been studied. Conductivity value was determined at room temperature. Energy activation conductivity and films optical band gap have been calculated. Temperature and field dependence of the drift mobility of charge carriers in the HF As-S-Se films have been shown. Bipolarity of charge carriers drift mobility has been confirmed. Absence of deep traps for electrons in the As{sub 40}Se{sub 30}S{sub 30} spectrum of localized states for films obtained by HF plasma ion sputtering was determined. Bipolar drift of charge carriers was found in amorphous As{sub 40}Se{sub 30}S{sub 30} films obtained by ion-plasma sputtering of high-frequency, unlike the films of these materials obtained by thermal evaporation.

  5. Amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-04-01

    Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

  6. Influence of the Composition on the Thermoelectric and Electro-physical Properties of Ge-Sb-Te Thin Films for Phase Change Memory Application

    Directory of Open Access Journals (Sweden)

    P.I. Lazarenko

    2016-10-01

    Full Text Available Influence of the composition variation along the quasi-binary line GeTe-Sb2Te3 on the thermoelectric and electro-physical properties of thin films was investigated. GST amorphous thin films have high Seebeck coefficients, which drops nearly on the order of magnitude after the crystallization. Temperature dependences of the resistivities were studied, and it was determined that crystallization temperature increases with moving along the quasi-binary line GeTe-Sb2Te3 from GeSb4Te7 to GeSb2Te4, and then to Ge2Sb2Te5, while the phase transition temperature range decreases. Current-voltage characteristics of amorphous thin films have three voltage ranges with different dependencies due to the different mechanisms of charge carrier transport.

  7. Toward stratified treatments for bipolar disorders.

    Science.gov (United States)

    Hasler, Gregor; Wolf, Andreas

    2015-03-01

    In bipolar disorders, there are unclear diagnostic boundaries with unipolar depression and schizophrenia, inconsistency of treatment guidelines, relatively long trial-and-error phases of treatment optimization, and increasing use of complex combination therapies lacking empirical evidence. These suggest that the current definition of bipolar disorders based on clinical symptoms reflects a clinically and etiologically heterogeneous entity. Stratification of treatments for bipolar disorders based on biomarkers and improved clinical markers are greatly needed to increase the efficacy of currently available treatments and improve the chances of developing novel therapeutic approaches. This review provides a theoretical framework to identify biomarkers and summarizes the most promising markers for stratification regarding beneficial and adverse treatment effects. State and stage specifiers, neuropsychological tests, neuroimaging, and genetic and epigenetic biomarkers will be discussed with respect to their ability to predict the response to specific pharmacological and psychosocial psychotherapies for bipolar disorders. To date, the most reliable markers are derived from psychopathology and history-taking, while no biomarker has been found that reliably predicts individual treatment responses. This review underlines both the importance of clinical diagnostic skills and the need for biological research to identify markers that will allow the targeting of treatment specifically to sub-populations of bipolar patients who are more likely to benefit from a specific treatment and less likely to develop adverse reactions.

  8. Bipolar batteries based on Ebonex ® technology

    Science.gov (United States)

    Loyns, A. C.; Hill, A.; Ellis, K. G.; Partington, T. J.; Hill, J. M.

    Continuing work by Atraverda on the production of a composite-laminate form of the Ebonex ® material, that can be cheaply formulated and manufactured to form substrate plates for bipolar lead-acid batteries, is described. Ebonex ® is the registered trade name of a range of titanium suboxide ceramic materials, typically Ti 4O 7 and Ti 5O 9, which combine electrical conductivity with high corrosion and oxidation resistance. Details of the structure of the composite, battery construction techniques and methods for filling and forming of batteries are discussed. In addition, lifetime and performance data obtained by Atraverda from laboratory bipolar lead-acid batteries and cells are presented. Battery production techniques for both conventional monopolar and bipolar batteries are reviewed. The findings indicate that substantial time and cost savings may be realised in the manufacture of bipolar batteries in comparison to conventional designs. This is due to the fewer processing steps required and more efficient formation. The results indicate that the use of Ebonex ® composite material as a bipolar substrate will provide lightweight and durable high-voltage lead-acid batteries suitable for a wide range of applications including advanced automotive, stationary power and portable equipment.

  9. Mechanism of GeSbTe phase change materials: an ab initio molecular dynamics study

    Science.gov (United States)

    Raty, Jean-Yves; Otjacques, Céline; Gaspard, Jean-Pierre; Bichara, Christophe

    2008-03-01

    Among phase change materials, Ge2Sb2Te5 (225) is one of the most successfully used in applications. Accepted models are based on EXAFS spectra and suppose a complete reorganization of bonds during amorphization, with Ge changing from sixfold to tetrahedral coordination. We perform ab initio MD simulations of the (225), (124) and (415) liquid alloys. We show that the crystalline, liquid and amorphous structure of these systems are similar, with very little sp3 hybridization around Ge atoms and a majority of p-sigma bonds. Using a set of quenched liquid configurations we reproduce the EXAFS measurements on the (225) composition and explain how the static Debye Waller factor due to the vacancies in the crystal phase leads to a cancellation of individual neighbors contribution to the EXAFS signal while in the amorphous, a larger coherence occurs, enhancing the EXAFS signal. The computed electrical conductivities of the three phases (cubic solid, liquid and amorphous) prove to be very different, accordingly with the experiment.

  10. Application of Bipolar Fuzzy Sets in Graph Structures

    Directory of Open Access Journals (Sweden)

    Muhammad Akram

    2016-01-01

    Full Text Available A graph structure is a useful tool in solving the combinatorial problems in different areas of computer science and computational intelligence systems. In this paper, we apply the concept of bipolar fuzzy sets to graph structures. We introduce certain notions, including bipolar fuzzy graph structure (BFGS, strong bipolar fuzzy graph structure, bipolar fuzzy Ni-cycle, bipolar fuzzy Ni-tree, bipolar fuzzy Ni-cut vertex, and bipolar fuzzy Ni-bridge, and illustrate these notions by several examples. We study ϕ-complement, self-complement, strong self-complement, and totally strong self-complement in bipolar fuzzy graph structures, and we investigate some of their interesting properties.

  11. Immune activation by casein dietary antigens in bipolar disorder

    NARCIS (Netherlands)

    Severance, E.G.; Dupont, D.; Dickerson, F.B.; Stallings, C.R.; Origoni, A.E.; Krivogorsky, B.; Yang, S.; Haasnoot, W.; Yolken, R.H.

    2010-01-01

    Objectives: Inflammation and other immune processes are increasingly linked to psychiatric diseases. Antigenic triggers specific to bipolar disorder are not yet defined. We tested whether antibodies to bovine milk caseins were associated with bipolar disorder, and whether patients recognized differe

  12. Pediatric Bipolar Disorder and Mood Dysregulation: Diagnostic Controversies.

    Science.gov (United States)

    Shain, Benjamin N

    2014-08-01

    Pediatric bipolar disorder, once thought rare, has gone through stages of conceptualization. DSM criteria were reinterpreted such that children and adolescents, particularly those with ADHD, were commonly diagnosed with bipolar disorder and thought to be atypical by adult standards. Research criteria separated pediatric bipolar patients into 3 phenotypes, including a research diagnosis of "severe mood dysregulation." DSM-5 largely maintained previous criteria for bipolar disorder at all ages and created a new diagnosis called "disruptive mood dysregulation disorder," categorized as a depressive disorder, for persistently angry or irritable patients with symptoms of childhood onset. However, the controversy regarding the diagnosis of pediatric bipolar disorder continues. Progress has been made in the classification of children and adolescents with mood symptoms who are predominantly irritable or angry, but lack of clarity remains regarding classification of children and adolescents with "symptoms characteristic of bipolar disorder" who do not meet criteria for bipolar I disorder, bipolar II disorder, or cyclothymia.

  13. Assessment of subjective and objective cognitive function in bipolar disorder

    DEFF Research Database (Denmark)

    Demant, Kirsa M; Vinberg, Maj; Kessing, Lars V

    2015-01-01

    Cognitive dysfunction is prevalent in bipolar disorder (BD). However, the evidence regarding the association between subjective cognitive complaints, objective cognitive performance and psychosocial function is sparse and inconsistent. Seventy seven patients with bipolar disorder who presented...

  14. Cytokines in bipolar disorder vs. healthy control subjects

    DEFF Research Database (Denmark)

    Munkholm, Klaus; Braüner, Julie Vestergaard; Kessing, Lars Vedel

    2013-01-01

    Bipolar disorder may be associated with peripheral immune system dysfunction; however, results in individual studies are conflicting. Our aim was to systematically review evidence of peripheral cytokine alterations in bipolar disorder integrating findings from various affective states....

  15. Kids with Bipolar Disorder More Likely to Abuse Drugs, Alcohol

    Science.gov (United States)

    ... html Kids With Bipolar Disorder More Likely to Abuse Drugs, Alcohol: Study And those who also have conduct disorder ... with bipolar disorder, the risk that they will abuse alcohol and drugs may increase as they get older, ...

  16. Differences between Depression Episodes of Bipolar Disorder I and II

    Directory of Open Access Journals (Sweden)

    Leman Inanc

    2013-09-01

    Full Text Available In 1975 Fieve and Dunner made the distinction between hypomania and mania as hypomania does not usually cause social and occupational impair-ment and hospitalization is not needed, moreover patients do not experience psychosis. Bipolar disorder type I is defined by the presence of manic and depressive episodes and differs from Bipolar disorder type II characterized with hipomanic and depressive episodes. Bipolar disorder type I and II do not differ in their depressive episodes. It is still point of contention whether bipolar type II is a variant of bipolar disorder type I or is positioned on the spectrum between bipolar type I and unipolar disorder. Even there are some similarities in characteristics of depressive episodes and outcome features of different bipolar disorder subtypes, there are differences that can be useful in differential diagnosis and treatment. This paper aims to focus on those differences between bipolar disorder type I and II.

  17. Anticonvulsant Drugs for Nerve Pain, Bipolar Disorder and Fibromyalgia

    Science.gov (United States)

    Anticonvulsant Drugs for Nerve Pain, Bipolar Disorder &Fibromyalgia: Choosing What’sRight for You What are anticonvulsant drugs? Anticonvulsants are drugs used to treat seizures. They are also used to treat bipolar ...

  18. A minimum thermodynamic model for the bipolar seesaw

    DEFF Research Database (Denmark)

    Stocker, Thomas F.; Johnsen, Sigfus Johann

    2003-01-01

    Bipolar seesaw, synchronization of Antarctic and Greenland ice cores, Dansgaard-Oeschger events, north-south connection......Bipolar seesaw, synchronization of Antarctic and Greenland ice cores, Dansgaard-Oeschger events, north-south connection...

  19. Twelve-bit 20-GHz reduced size pipeline accumulator in 0.25 µm SiGe:C technology for direct digital synthesiser applications

    DEFF Research Database (Denmark)

    Jensen, Brian Sveistrup; Khafaji, M. Mahdi; Johansen, Tom Keinicke

    2012-01-01

    This article presents a 20 GHz, 12-bit pipeline accumulator with a reduced number of registers, suitable for direct digital synthesizer (DDS) applications. The accumulator is implemented in the IHP SG25H1 (0.25um) SiGe:C technology featuring heterojunction bipolar transistors (HBT) with Ft/Fmax o...

  20. Mechanisms of centrosome separation and bipolar spindle assembly.

    Science.gov (United States)

    Tanenbaum, Marvin E; Medema, René H

    2010-12-14

    Accurate segregation of chromosomes during cell division is accomplished through the assembly of a bipolar microtubule-based structure called the mitotic spindle. Work over the past two decades has identified a core regulator of spindle bipolarity, the microtubule motor protein kinesin-5. However, an increasing body of evidence has emerged demonstrating that kinesin-5-independent mechanisms driving bipolar spindle assembly exist as well. Here, we discuss different pathways that promote initial centrosome separation and bipolar spindle assembly.

  1. Voltage regulator for battery power source. [using a bipolar transistor

    Science.gov (United States)

    Black, J. M. (Inventor)

    1979-01-01

    A bipolar transistor in series with the battery as the control element also in series with a zener diode and a resistor is used to maintain a predetermined voltage until the battery voltage decays to very nearly the predetermined voltage. A field effect transistor between the base of the bipolar transistor and a junction between the zener diode and resistor regulates base current of the bipolar transistor, thereby regulating the conductivity of the bipolar transistor for control of the output voltage.

  2. Plain carbon steel bipolar plates for PEMFC

    Institute of Scientific and Technical Information of China (English)

    WANG Jianli; SUN Juncai; TIAN Rujin; XU Jing

    2006-01-01

    Bipolar plates are a multifunctional component of PEMFC. Comparing with the machined graphite and stainless steels, the plain carbon steel is a very cheap commercial metal material. In this paper, the possibility of applying the plain carbon steels in the bipolar plate for PEMFC was exploited. In order to improve the corrosion resistance of the low carbon steel in the PEMFCs' environments,two surface modification processes was developed and then the electrochemical performances and interfacial contact resistance (ICR) of the surface modified plate of plain carbon steel were investigated. The results show that the surface modified steel plates have good corrosion resistance and relatively low contact resistance, and it may be a candidate material as bipolar plate of PEMFC.

  3. Family Functioning and the Course of Adolescent Bipolar Disorder

    Science.gov (United States)

    Sullivan, Aimee E.; Judd, Charles M.; Axelson, David A.; Miklowitz, David J.

    2012-01-01

    The symptoms of bipolar disorder affect and are affected by the functioning of family environments. Little is known, however, about the stability of family functioning among youth with bipolar disorder as they cycle in and out of mood episodes. This study examined family functioning and its relationship to symptoms of adolescent bipolar disorder,…

  4. Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

    KAUST Repository

    Chaieb, Sahraoui

    2015-04-09

    Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

  5. Synthesis of Epitaxial Films Based on Ge-Si-Sn Materials with Ge/GeSn, Ge/GeSiSn, and GeSn/GeSiSn Heterojunctions

    Science.gov (United States)

    Timofeev, V. A.; Kokhanenko, A. P.; Nikiforov, A. I.; Mashanov, V. I.; Tuktamyshev, A. R.; Loshkarev, I. D.

    2015-11-01

    Results of investigations into the synthesis of heterostructures based on Ge-Si-Sn materials by the method of low-temperature molecular beam epitaxy are presented. The formation of epitaxial films during structure growth has been controlled by the reflection high-energy electron diffraction method. Films with Ge/GeSn, Ge/GeSiSn, and GeSn/GeSiSn heterojunctions are grown with Sn content changing from 2 to 10 % at temperatures in the interval 150-350°C. The stressed state, the composition, and the lattice parameter are studied by the x-ray diffraction method using Omega-scan curves and reciprocal space maps. A tensile strain in the Ge film during Ge/Ge0.9Sn0.1/Si structure growth has reached 0.86%.

  6. Climatic factors and bipolar affective disorder

    DEFF Research Database (Denmark)

    Christensen, Ellen Margrethe; Larsen, Jens Knud; Gjerris, Annette;

    2008-01-01

    . A group of patients with at least three previous hospitalizations for bipolar disorder was examined every 3 months for up to 3 years. At each examination an evaluation of the affective phase was made according to the Hamilton Depression Scale (HAM-D(17)), and the Bech-Rafaelsen Mania Rating Scale (MAS......). In the same period, daily recordings from the Danish Meteorological Institute were received. We found no correlations between onset of bipolar episodes [defined as MAS score of 11 or more (mania) and as HAM-D(17) score of 12 or more (depression)] and any meteorological parameters. We found a statistical...

  7. Bipolar effects in unipolar junctionless transistors

    Science.gov (United States)

    Parihar, Mukta Singh; Ghosh, Dipankar; Armstrong, G. Alastair; Yu, Ran; Razavi, Pedram; Kranti, Abhinav

    2012-08-01

    In this work, we analyze hysteresis and bipolar effects in unipolar junctionless transistors. A change in subthreshold drain current by 5 orders of magnitude is demonstrated at a drain voltage of 2.25 V in silicon junctionless transistor. Contrary to the conventional theory, increasing gate oxide thickness results in (i) a reduction of subthreshold slope (S-slope) and (ii) an increase in drain current, due to bipolar effects. The high sensitivity to film thickness in junctionless devices will be most crucial factor in achieving steep transition from ON to OFF state.

  8. A report on older-age bipolar disorder from the International Society for Bipolar Disorders Task Force

    DEFF Research Database (Denmark)

    Sajatovic, Martha; Strejilevich, Sergio A; Gildengers, Ariel G

    2015-01-01

    OBJECTIVES: In the coming generation, older adults with bipolar disorder (BD) will increase in absolute numbers as well as proportion of the general population. This is the first report of the International Society for Bipolar Disorder (ISBD) Task Force on Older-Age Bipolar Disorder (OABD). METHODS...

  9. Three times more days depressed than manic or hypomanic in both bipolar I and bipolar II disorder

    NARCIS (Netherlands)

    Kupka, Ralph W.; Altshuler, Lori L.; Nolen, Willem A.; Suppes, Trisha; Luckenbaugh, David A.; Leverich, Gabriele S.; Frye, Mark A.; Keck, Paul E.; McElroy, Susan L.; Grunze, Heinz; Post, Robert M.

    2007-01-01

    Objectives: To assess the proportion of time spent in mania, depression and euthymia in a large cohort of bipolar subjects studied longitudinally, and to investigate depression/mania ratios in patients with bipolar I versus bipolar II disorder. Methods: Clinician-adjusted self-ratings of mood were c

  10. Alcoholism and anxiety in bipolar illness : Differential lifetime anxiety comorbidity in bipolar I women with and without alcoholism

    NARCIS (Netherlands)

    Levander, Eric; Frye, Mark A.; McElroy, Susan; Suppes, Trisha; Grunze, Heinz; Nolen, Willem A.; Kupka, Ralph; Keck, Paul E.; Leverich, Gabriele S.; Altshuler, Lori L.; Hwang, Sun; Mintz, Jim; Post, Robert M.

    2007-01-01

    Introduction: This study was undertaken to evaluate the prevalence rate of anxiety comorbidity in bipolar subjects with and without alcohol use disorders (AUD). Methods: Bipolar men and women who entered the Stanley Foundation Bipolar Network (SFBN) underwent a Structured Clinical Interview for DSM-

  11. On Structure and Properties of Amorphous Materials

    Directory of Open Access Journals (Sweden)

    Zbigniew H. Stachurski

    2011-09-01

    Full Text Available Mechanical, optical, magnetic and electronic properties of amorphous materials hold great promise towards current and emergent technologies. We distinguish at least four categories of amorphous (glassy materials: (i metallic; (ii thin films; (iii organic and inorganic thermoplastics; and (iv amorphous permanent networks. Some fundamental questions about the atomic arrangements remain unresolved. This paper focuses on the models of atomic arrangements in amorphous materials. The earliest ideas of Bernal on the structure of liquids were followed by experiments and computer models for the packing of spheres. Modern approach is to carry out computer simulations with prediction that can be tested by experiments. A geometrical concept of an ideal amorphous solid is presented as a novel contribution to the understanding of atomic arrangements in amorphous solids.

  12. Sleep disturbances in pediatric bipolar disorder: A comparison between Bipolar I and Bipolar NOS

    Directory of Open Access Journals (Sweden)

    Argelinda eBaroni

    2012-03-01

    Full Text Available Introduction: The diagnosis of Bipolar Disorder (BD in youths has been controversial, especially for the subtype BD Not Otherwise Specified (BD-NOS. In spite of growing evidence that sleep is a core feature of BD, few studies characterize and compare sleep disturbances in youth with BD type I (BD-I and BD-NOS. Sleep disturbances are frequently reported in clinical descriptions of children and adolescents with BD, however the reporting of the frequency and characteristics of sleep symptoms in youth with BD NOS and BD I during episodes remain poor. This study compares symptom of sleep disturbance as occurring in manic and depressive episodes in BD I and BD NOS youth using KSADS-PL interview data. The study also addresses whether symptoms of sleep disturbance vary in different age groups. Material and Methods: The sample consisted of 70 children and adolescent outpatients at an urban specialty clinic (42M/28F, 10.8±3.6 years old including 24 BP-I and 46 BP-NOS assessed using K-SADS-PL-parent interview. Results: Sleep disturbances including insomnia and decreased need for sleep were reported by 84.3% of the sample. Enuresis was diagnosed in 27% of sample. There were no significant differences in frequency of sleep symptoms between BD-I and BD-NOS. Regardless of BD subtype, current functioning was negatively correlated with decreased need for sleep but not insomnia, and regardless of BD subtype. Conclusion: The majority of youth with BD presents with sleep symptoms during mood episodes. BD NOS presents with the same proportion of sleep symptoms as BD I in our sample.

  13. Switching of localized surface plasmon resonance of gold nanoparticles on a GeSbTe film mediated by nanoscale phase change and modification of surface morphology

    Science.gov (United States)

    Hira, T.; Homma, T.; Uchiyama, T.; Kuwamura, K.; Saiki, T.

    2013-12-01

    As a platform for active nanophotonics, localized surface plasmon resonance (LSPR) switching via interaction with a chalcogenide phase change material (GeSbTe) was investigated. We performed single-particle spectroscopy of gold nanoparticles placed on a GeSbTe thin film. By irradiation with a femtosecond pulsed laser for amorphization and a continuous wave laser for crystallization, significant switching behavior of the LSPR band due to the interaction of GeSbTe was observed. The switching mechanism was explained in terms of both a change in the refractive index and a modification of surface morphology accompanying volume expansion and reduction of GeSbTe.

  14. Switching of localized surface plasmon resonance of gold nanoparticles on a GeSbTe film mediated by nanoscale phase change and modification of surface morphology

    Energy Technology Data Exchange (ETDEWEB)

    Hira, T.; Homma, T.; Uchiyama, T.; Kuwamura, K.; Saiki, T. [Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Kanagawa 223-8522 (Japan)

    2013-12-09

    As a platform for active nanophotonics, localized surface plasmon resonance (LSPR) switching via interaction with a chalcogenide phase change material (GeSbTe) was investigated. We performed single-particle spectroscopy of gold nanoparticles placed on a GeSbTe thin film. By irradiation with a femtosecond pulsed laser for amorphization and a continuous wave laser for crystallization, significant switching behavior of the LSPR band due to the interaction of GeSbTe was observed. The switching mechanism was explained in terms of both a change in the refractive index and a modification of surface morphology accompanying volume expansion and reduction of GeSbTe.

  15. Effect of Co and Ge addition on soft magnetic properties of Fe-Zr-B-Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blazquez, J.S. [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany) and Departamento de Fisica de la Materia Condensada - ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065. 41080 Sevilla (Spain)]. E-mail: jsebas@us.es; Roth, S. [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany); Conde, A. [Departamento de Fisica de la Materia Condensada. ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065. 41080 Sevilla (Spain)

    2005-04-15

    Microstructure and magnetic properties are studied for Fe{sub 78}Co{sub 5}Zr{sub 6}Ge{sub 5}B{sub 5}Cu{sub 1} alloy. Curie temperature of the amorphous phase is increased by 200 K with respect to Fe-Zr-B-Ge-Cu alloys, without losing the ultrasoft magnetic properties exhibited at room temperature (H {sub C}{approx}10 A/m). Nanocrystalline microstructure shows a high crystalline volume fraction of {alpha}-Fe nanocrystals ({approx}0.85) with size below 13 nm. Ge content in the crystalline phase is found to decrease continuously during nanocrystallization.

  16. The physics and applications of amorphous semiconductors

    CERN Document Server

    Madan, Arun

    1988-01-01

    This comprehensive, detailed treatise on the physics and applications of the new emerging technology of amorphous semiconductors focuses on specific device research problems such as the optimization of device performance. The first part of the book presents hydrogenated amorphous silicon type alloys, whose applications include inexpensive solar cells, thin film transistors, image scanners, electrophotography, optical recording and gas sensors. The second part of the book discusses amorphous chalcogenides, whose applications include electrophotography, switching, and memory elements. This boo

  17. Recent developments in amorphous silicon-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Beneking, C.; Rech, B.; Foelsch, J.; Wagner, H. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Schicht- und Ionentechnik

    1996-03-01

    Two examples of recent advances in the field of thin-film, amorphous hydrogenated silicon (a-Si:H) pin solar cells are described: the improved understanding and control of the p/i interface, and the improvement of wide-bandgap a-Si:H material deposited at low substrate temperature as absorber layer for cells with high stabilized open-circuit voltage. Stacked a-Si:H/a-Si:H cells incorporating these concepts exhibit less than 10% (relative) efficiency degradation and show stabilized efficiencies as high as 9 to 10% (modules 8 to 9%). The use of low-gap a-Si:H and its alloys like a-SiGe:H as bottom cell absorber materials in multi-bandgap stacked cells offers additional possibilities. The combination of a-Si:H based top cells with thin-film crystalline silicon-based bottom cells appears as a promising new trend. It offers the perspective to pass significantly beyond the present landmark of 10% module efficiency reached by the technology utilizing exclusively amorphous silicon-based absorber layers, while keeping its advantages of potentially low-cost production. (orig.) 47 refs.

  18. Anomalous activation of shallow B+ implants in Ge

    DEFF Research Database (Denmark)

    Yates, B.R.; Darby, B.L.; Rudawski, N.G.;

    2011-01-01

    The electrical activation of B+ implantation at 2 keV to doses of 5.0×1013-5.0×1015 cm-2 in crystalline and pre-amorphized Ge following annealing at 400 °C for 1.0 h was studied using micro Hall effect measurements. Preamorphization improved activation for all samples with the samples implanted...... to a dose of 5.0×1015 cm-2 displaying an estimated maximum active B concentration of 4.0×1020 cm-3 as compared to 2.0×1020 cm-3 for the crystalline sample. However, incomplete activation was observed for all samples across the investigated dose range. For the sample implanted to a dose of 5.0×1013 cm -2......, activation values were 7% and 30%, for c-Ge and PA-Ge, respectively. The results suggest the presence of an anomalous clustering phenomenon of shallow B+ implants in Ge. © 2011 Elsevier B.V. All rights reserved....

  19. Structural study of amorphous polyaniline

    Science.gov (United States)

    Laridjani, M.; Pouget, J. P.; MacDiarmid, A. G.; Epstein, A. J.

    1992-06-01

    Many materials, especially polymers, have a substantial volume fraction with no long range crystalline order. Through these regions are often termed amorphous, they frequently have a specific local order. We describe and use here a method, base on a non-energy dispersive X-ray diffraction technique, to obtain good quality interference functions and, by Fourier transform, radial distribution functions of the amorphous structure of polymers. We apply this approach to members of a family of electronic polymers of current interest : polyaniline emeraldine bases. We show that the local order exhibits significant differences in type I and type II materials, precipitated as salt and base respectively. These studies demonstrate the importance of sample preparation in evaluating the physical properties of polyaniline, and provide a structural origin for memory effects observed in the doping-dedoping processes. Beaucoup de matériaux, spécialement les polymères, ont une importante fraction de leur volume sans ordre cristallin à longue portée. Bien que ces régions soient souvent appelées amorphes, elles présentent fréquemment un ordre local caractéristique. Nous décrivons et utilisons dans ce papier une méthode, basée sur une technique de diffraction de rayons X non dispersive en énergie, pour obtenir des fonctions d'interférence de bonne qualité et, par transformée de Fourier, la fonction de distribution radiale des polymères amorphes. Nous appliquons cette technique à plusieurs éléments d'une même famille de polymères électroniques d'intérêt actuel : les polyanilines éméraldine bases. Nous montrons que l'ordre local présente d'appréciables différences dans les matériaux de type I et II, préparés respectivement sous forme de sel et de base. Cette étude démontre l'importance des conditions de préparation sur les propriétés physiques du polyaniline et donne une base structurale aux effets observés dans les processus de dopage-dédopage de

  20. Fracture Phenomena in Amorphous Selenium

    DEFF Research Database (Denmark)

    Lindegaard-Andersen, Asger; Dahle, Birgit

    1966-01-01

    the velocities of ultrasonic longitudinal and shear waves were measured to 1820 m/sec and 930 m/sec, respectively. Based on these results the two line systems in the transition zone can be interpreted as ``Wallner lines'' with sources within the zone. ©1966 The American Institute of Physics......Fracture surfaces of amorphous selenium broken in flexure at room temperature have been studied. The fracture velocity was found to vary in different regions of the fracture surface. Peculiar features were observed in a transition zone between fast and slower fracture. In this zone cleavage steps...

  1. Influence of Ge content and annealing conditions on the PL properties of nc-Si{sub 1−x}Ge{sub x} embedded in SiO{sub 2} matrix in weak quantum confined regime

    Energy Technology Data Exchange (ETDEWEB)

    Tuğay, Evrin, E-mail: evrin.tugay@erdogan.edu.tr [Department of Mechanical Engineering, Faculty of Engineering, Recep Tayyip Erdogan University, Rize 53100 (Turkey); Ilday, Serim [Department of Micro and Nanotechnology, Middle East Technical University, Ankara (Turkey); Center of Solar Energy Research and Application (GÜNAM), Middle East Technical University (METU), 06531 Ankara (Turkey); Turan, Raşit [Center of Solar Energy Research and Application (GÜNAM), Middle East Technical University (METU), 06531 Ankara (Turkey); Department of Physics, Middle East Technical University, Ankara (Turkey); Finstad, Treje G. [Department of Physics, University of Oslo, Oslo (Norway)

    2014-11-15

    Fabrication of Si (nc-Si), Ge (nc-Ge), and Si{sub 1−x}Ge{sub x} (nc-Si{sub 1−x}Ge{sub x}) nanocrystals embedded in SiO{sub 2} matrix is achieved by thermal annealing of magnetron-sputtered thin films. Effects of annealing conditions, namely duration and temperature, as well as Ge content on the photoluminescence properties are investigated. Origin and evolution of the photoluminescence signal in the weak quantum confinement regime are discussed. It is found that photoluminescence signals can be decomposed into four Gaussian peaks originating from Ge-related radiative defects located at the sub-oxide (GeO{sub x}), either inside the matrix or at the interface region (peak M), nc-Si{sub 1−x}Ge{sub x}/SiO{sub 2} interface-related localized states (peak I), localized states in the amorphous Si{sub 1−x}Ge{sub x} bandgap (peak A) and quantum confinement of excitons in small nanocrystals (peak Q). The role of small and large nanocrystals in the photoluminescence mechanism is investigated by varying the mean nanocrystal size from 3 nm to 23 nm (from strong to weak quantum confined regime). Our results demonstrate that the quantum confinement effect in Ge nanocrystals manifests though spectral blueshift due to increase in Ge content. We also propose that the decreasing photoluminescence signal intensity with an increase in Ge content may originate from Ge-related nonradiative P{sub b} centers. - Highlights: • Origin and evolution of PL in weak quantum confinement regime are investigated. • It is necessary to distinguish between the role of smaller and larger nanocrystals. • Blueshift and PL quenching by incorporation of more Ge atoms has been observed.

  2. Characteristics of Sn segregation in Ge/GeSn heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.; Chang, C.; Chen, T. P.; Cheng, H. H., E-mail: hhcheng@ntu.edu.tw [Center for Condensed Matter Sciences and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Shi, Z. W.; Chen, H. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-10-13

    We report an investigation of Sn segregation in Ge/GeSn heterostructures occurred during the growth by molecular beam epitaxy. The measured Sn profile in the Ge layer shows that: (a) the Sn concentration decreases rapidly near the Ge/GeSn interface, and (b) when moving away from the interface, the Sn concentration reduced with a much slower rate. The 1/e decay lengths of the present system are much longer than those of the conventional group IV system of Ge segregation in the Si overlayer because of the smaller kinetic potential as modeled by a self-limited two-state exchange scheme. The demonstration of the Sn segregation shows the material characteristics of the heterostructure, which are needed for the investigation of its optical properties.

  3. Phonons in Ge/Si superlattices with Ge quantum dots

    CERN Document Server

    Milekhin, A G; Pchelyakov, O P; Schulze, S; Zahn, D R T

    2001-01-01

    Ge/Si superlattices with Ge quantum dots obtained by means of molecular-beam epitaxy were investigated by means of light Raman scattering under resonance conditions. These structures are shown to have oscillation properties of both two-dimensional and zero-dimensional objects. Within spectrum low-frequency range one observes twisted acoustic phonons (up to 15 order) typical for planar superlattices. Lines of acoustic phonons are overlapped with a wide band of continuous emission. Analysis of frequencies of Ge and Ge-Si optical phonons shows that Ge quantum dots are pseudoamorphous ones and mixing of Ge and Si atoms is a negligible one. One detected low-frequency shift of longitudinal optical phonons at laser excitation energy increase (2.54-2.71 eV)

  4. Heritability of cognitive functions in families with bipolar disorder.

    Science.gov (United States)

    Antila, Mervi; Tuulio-Henriksson, Annamari; Kieseppä, Tuula; Soronen, Pia; Palo, Outi M; Paunio, Tiina; Haukka, Jari; Partonen, Timo; Lönnqvist, Jouko

    2007-09-01

    Bipolar disorder is highly heritable. Cognitive dysfunctions often observed in bipolar patients and their unaffected relatives implicate that these impairments may be associated with genetic predisposition to bipolar disorder and thus fulfill the criteria of a valid endophenotype for the disorder. However, the most fundamental criterion, their heritability, has not been directly studied in any bipolar population. This population-based study estimated the heritability of cognitive functions in bipolar disorder. A comprehensive neuropsychological test battery and the Structured Clinical Interview for DSM-IV were administered to a population-based sample of 110 individuals from 52 families with bipolar disorder. Heritability of cognitive functions as assessed with neuropsychological test scores were estimated using the Solar package. Significant additive heritabilities were found in verbal ability, executive functioning, and psychomotor processing speed. Genetic contribution was low to verbal learning functions. High heritability, in executive functioning and psychomotor processing speed suggest that these may be valid endophenotypic traits for genetic studies of bipolar disorder.

  5. Psychoeducation for bipolar disorder: A discourse analysis.

    Science.gov (United States)

    Wilson, Lynere; Crowe, Marie; Scott, Anne; Lacey, Cameron

    2017-03-16

    Psychoeducation has become a common intervention within mental health settings. It aims to increase people's ability to manage a life with a long-term illness. For people with bipolar disorder, psychoeducation is one of a range of psychosocial interventions now considered part of contemporary mental health practice. It has taken on a 'common sense' status that results in little critique of psychoeducation practices. Using a published manual on psychoeducation and bipolar disorder as its data, Foucauldian discourse analysis was used in the present study for a critical perspective on psychoeducation in order to explore the taken-for-granted assumptions on which it is based. It identifies that the text produces three key subject positions for people with bipolar disorder. To practice self-management, a person must: (i) accept and recognize the authority of psychiatry to know them; (ii) come to see that they can moderate themselves; and (iii) see themselves as able to undertake a reflexive process of self-examination and change. These findings highlight the circular and discursive quality to the construct of insight that is central to how psychoeducation is practiced. Using Foucault's construct of pastoral power, it also draws attention to the asymmetrical nature of power relations between the clinician and the person with bipolar disorder. An effect of the use of medical discourse in psychoeducation is to limit its ability to work with ambivalence and contradiction. A critical approach to psychotherapy and education offers an alternate paradigm on which to basis psychoeducation practices.

  6. Homocysteine and cognitive functions in bipolar depression

    Directory of Open Access Journals (Sweden)

    Agnieszka Permoda-Osip

    2014-12-01

    The results obtained show higher HCY concentration in considerable proportion of patients with bipolar depression, especially in men. They also confirm a connect between high homocysteine concentration and worse performance in some neuropsychological tests. Such relationship was more marked in men.

  7. Cognitive enhancement treatments for bipolar disorder

    DEFF Research Database (Denmark)

    Miskowiak, Kamilla W; Carvalho, André F; Vieta, Eduard

    2016-01-01

    Cognitive dysfunction is an emerging treatment target in bipolar disorder (BD). Several trials have assessed the efficacy of novel pharmacological and psychological treatments on cognition in BD but the findings are contradictory and unclear. A systematic search following the PRISMA guidelines...

  8. Heart rate variability in bipolar disorder

    DEFF Research Database (Denmark)

    Faurholt-Jepsen, Maria; Kessing, Lars Vedel; Munkholm, Klaus

    2016-01-01

    BACKGROUND: Heart rate variability (HRV) has been suggested reduced in bipolar disorder (BD) compared with healthy individuals (HC). This meta-analysis investigated: HRV differences in BD compared with HC, major depressive disorder or schizophrenia; HRV differences between affective states; HRV...

  9. Bias in emerging biomarkers for bipolar disorder

    DEFF Research Database (Denmark)

    Carvalho, A F; Köhler, C A; Fernandes, B S

    2016-01-01

    BACKGROUND: To date no comprehensive evaluation has appraised the likelihood of bias or the strength of the evidence of peripheral biomarkers for bipolar disorder (BD). Here we performed an umbrella review of meta-analyses of peripheral non-genetic biomarkers for BD. METHOD: The Pubmed...

  10. Titanium Carbide Bipolar Plate for Electrochemical Devices

    Energy Technology Data Exchange (ETDEWEB)

    LaConti, Anthony B.; Griffith, Arthur E.; Cropley, Cecelia C.; Kosek, John A.

    1998-05-08

    Titanium carbide comprises a corrosion resistant, electrically conductive, non-porous bipolar plate for use in an electrochemical device. The process involves blending titanium carbide powder with a suitable binder material, and molding the mixture, at an elevated temperature and pressure.

  11. Unraveling Psychomotor Slowing in Bipolar Disorde

    NARCIS (Netherlands)

    Morsel, A.M.; Temmerman, A.; Sabbe, B.G.C.; Hulstijn, W.; Morrens, M.

    2015-01-01

    Background/Aims: In addition to affective and cognitive symptomatology, psychomotor deficits are known to be present in bipolar disorder (BD). Psychomotor functioning includes all of the processes necessary for completing a movement, from planning to initiation and execution. While these psychomotor

  12. The ups and downs of bipolar disorder.

    Science.gov (United States)

    Kaufman, Kenneth R

    2003-06-01

    This brief historical overview of bipolar disorder addresses diagnosis, treatment, cost, creativity, suicide, and stigma with a review of the literature. This served as the introduction to the 27th Annual Scientific Meeting of the American Academy of Clinical Psychiatrists (51 references).

  13. Corrosion test cell for bipolar plates

    Science.gov (United States)

    Weisbrod, Kirk R.

    2002-01-01

    A corrosion test cell for evaluating corrosion resistance in fuel cell bipolar plates is described. The cell has a transparent or translucent cell body having a pair of identical cell body members that seal against opposite sides of a bipolar plate. The cell includes an anode chamber and an cathode chamber, each on opposite sides of the plate. Each chamber contains a pair of mesh platinum current collectors and a catalyst layer pressed between current collectors and the plate. Each chamber is filled with an electrolyte solution that is replenished with fluid from a much larger electrolyte reservoir. The cell includes gas inlets to each chamber for hydrogen gas and air. As the gases flow into a chamber, they pass along the platinum mesh, through the catalyst layer, and to the bipolar plate. The gas exits the chamber through passageways that provide fluid communication between the anode and cathode chambers and the reservoir, and exits the test cell through an exit port in the reservoir. The flow of gas into the cell produces a constant flow of fresh electrolyte into each chamber. Openings in each cell body is member allow electrodes to enter the cell body and contact the electrolyte in the reservoir therein. During operation, while hydrogen gas is passed into one chamber and air into the other chamber, the cell resistance is measured, which is used to evaluate the corrosion properties of the bipolar plate.

  14. Bipolarity and Ambivalence in Landscape Architecture

    NARCIS (Netherlands)

    Koh, J.

    2010-01-01

    Our discipline of landscape architecture contains bipolarity, not only in terms of landscape and architecture but also because the idea of landscape is both aesthetic and scientific. Furthermore, within landscape architecture there is a gap between design (as implied by architecture) and planning (i

  15. Mechanism on bipolar distribution of Permian brachiopods

    Institute of Scientific and Technical Information of China (English)

    Chengwen WANG; Songmei ZHANG

    2008-01-01

    By reasearch on geographic distribution, nine genera in bipolar distribution are selected from Permian brachiopods. These taxa originated from middle-high latitude areas in the boreal realm, of which five genera were derived from Late Carboniferous, and other four genera originated from Permian. They were all in bipolar distribution during some different stages in Permian. Specific diversity for each genus was high in the boreal realm, whereas in the Gondwana realm was very low. Perdurability was long in the boreal realm, and short in the Gondwana realm. It was the time when these nine genera came to their maximum diversity that these genera appeared in the Gondwana and formed bipolar distribution; while they also migrated to the low latitude from high latitude. This shows very close relationship between several main cooling events in Permian and the migration of genera from the boreal realm to the Gondwana realm through the Tethys. Therefore, the cooling events might be the main drive which caused these cold-water-type brachiopods migrated to the Gondwana realm and being bipolar distribution. In this process, the planula tolerance to warm water would be another important factor.

  16. Using Ge Secondary Phases to Enhance the Power Factor and Figure of Merit of Ge17Sb2Te20

    Science.gov (United States)

    Williams, Jared B.; Morelli, Donald T.

    2016-08-01

    Thermoelectric materials are the leading candidate today for applications in solid-state waste-heat recovery/cooling applications. Research and engineering has pushed the ZT, and overall conversion efficiency, of these materials to values which can be deemed practical for commercialization. However, many of the state-of-the-art thermoelectric materials of today utilize elements which are toxic, such as Ag, Pb, Tl, and Cd. Alloys of GeTe and Sb2Te3 were first explored for their applications in phase-change memory, because of their ability to rapidly alternate between crystalline and amorphous phases. Recently, these materials have been identified as materials with ZT (S 2 T/ρκ, where S is the Seebeck coefficient, ρ is the electrical resistivity, T is the operating temperature, and κ is the thermal conductivity) much greater than unity. In this work, the influence of elemental Ge as a secondary phase on transport in Ge17Sb2Te20 was explored. It was found that Ge introduces an additional scattering mechanism, which leads to increased electrical resistivity, Seebeck coefficient, and power factor values as high as 36 μW cm-1 K-2. The thermal conductivity was slightly reduced and the ZT was enhanced across the entire temperature range of measurement, with peak values greater than 2.

  17. XPS study on the selective wet etching mechanism of GeSbTe phase change thin films with tetramethylammonium hydroxide

    Science.gov (United States)

    Deng, Changmeng; Geng, Yongyou; Wu, Yiqun

    Phase change lithography has pretty potential applications for high density optical data storage mastering and micro/nano structure patterning because it is not restricted by optical diffraction limitation and at relatively low cost. GeSbTe, as an initially investigated material for phase change lithography, its mechanism of selective etching in inorganic or organic alkaline aqueous solutions, such as NaOH and tetramethylammonium hydroxide (TMAH), is still unknown. In this paper, XPS measurement is used to study the selective wet etching mechanism of GeSbTe phase change thin films with TMAH solution, and the results show that oxidization played an important role in the etching process. Ge, Sb and Te are oxidized into GeO2, Sb2O5 and TeO2, respectively, and then as the corresponding salts dissolved into the etchant solution. Ge-X (X is Ge, Sb or Te) bonds are first broken in the etching, then Sb-X bonds, and finally Te-Te bonds. To confirm the effect of oxidization in the etching, H2O2 as an oxidant is added into the TMAH solution, and the etching rates are increased greatly for both amorphous and crystalline states. The selective etching mechanism of Ge2Sb2Te5 phase change films is discussed by the difference of bonds breakage between the amorphous and crystalline states.

  18. Laser surface treatment of amorphous metals

    Science.gov (United States)

    Katakam, Shravana K.

    Amorphous materials are used as soft magnetic materials and also as surface coatings to improve the surface properties. Furthermore, the nanocrystalline materials derived from their amorphous precursors show superior soft magnetic properties than amorphous counter parts for transformer core applications. In the present work, laser based processing of amorphous materials will be presented. Conventionally, the nanocrystalline materials are synthesized by furnace heat treatment of amorphous precursors. Fe-based amorphous/nanocrystalline materials due to their low cost and superior magnetic properties are the most widely used soft magnetic materials. However, achieving nanocrystalline microstructure in Fe-Si-B ternary system becomes very difficult owing its rapid growth rate at higher temperatures and sluggish diffusion at low temperature annealing. Hence, nanocrystallization in this system is achieved by using alloying additions (Cu and Nb) in the ternary Fe-Si-B system. Thus, increasing the cost and also resulting in reduction of saturation magnetization. laser processing technique is used to achieve extremely fine nanocrystalline microstructure in Fe-Si-B amorphous precursor. Microstructure-magnetic Property-laser processing co-relationship has been established for Fe-Si-B ternary system using analytical techniques. Laser processing improved the magnetic properties with significant increase in saturation magnetization and near zero coercivity values. Amorphous materials exhibit excellent corrosion resistance by virtue of their atomic structure. Fe-based amorphous materials are economical and due to their ease of processing are of potential interest to synthesize as coatings materials for wear and corrosion resistance applications. Fe-Cr-Mo-Y-C-B amorphous system was used to develop thick coatings on 4130 Steel substrate and the corrosion resistance of the amorphous coatings was improved. It is also shown that the mode of corrosion depends on the laser processing

  19. Unmet needs of bipolar disorder patients

    Directory of Open Access Journals (Sweden)

    Hajda M

    2016-06-01

    Full Text Available Miroslav Hajda,1 Jan Prasko,1 Klara Latalova,1 Radovan Hruby,2 Marie Ociskova,1 Michaela Holubova,1,3 Dana Kamaradova,1 Barbora Mainerova1 1Department of Psychiatry, Faculty of Medicine and Dentistry, Palacky University Olomouc, University Hospital Olomouc, Olomouc, Czech Republic; 2Outpatient Psychiatric Department, Martin, Slovak Republic; 3Department of Psychiatry, Regional Hospital Liberec, Liberec, Czech Republic Background: Bipolar disorder (BD is a serious mental illness with adverse impact on the lives of the patients and their caregivers. BD is associated with many limitations in personal and interpersonal functioning and restricts the patients’ ability to use their potential capabilities fully. Bipolar patients long to live meaningful lives, but this goal is hard to achieve for those with poor insight. With progress and humanization of society, the issue of patients’ needs became an important topic. The objective of the paper is to provide the up-to-date data on the unmet needs of BD patients and their caregivers. Methods: A systematic computerized examination of MEDLINE publications from 1970 to 2015, via the keywords “bipolar disorder”, “mania”, “bipolar depression”, and “unmet needs”, was performed. Results: Patients’ needs may differ in various stages of the disorder and may have different origin and goals. Thus, we divided them into five groups relating to their nature: those connected with symptoms, treatment, quality of life, family, and pharmacotherapy. We suggested several implications of these needs for pharmacotherapy and psychotherapy. Conclusion: Trying to follow patients’ needs may be a crucial point in the treatment of BD patients. However, many needs remain unmet due to both medical and social factors. Keywords: bipolar disorder, unmet needs, stigma, treatment, medication, quality of life, family, psychotherapy

  20. Memantine: New prospective in bipolar disorder treatment

    Science.gov (United States)

    Serra, Giulia; Demontis, Francesca; Serra, Francesca; De Chiara, Lavinia; Spoto, Andrea; Girardi, Paolo; Vidotto, Giulio; Serra, Gino

    2014-01-01

    We review preclinical and clinical evidences strongly suggesting that memantine, an old drug currently approved for Alzheimer’s dementia, is an effective treatment for acute mania and for the prevention of manic/hypomanic and depressive recurrences of manic-depressive illness. Lithium remains the first line for the treatment and prophylaxis of bipolar disorders, but currently available treatment alternatives for lithium resistant patients are of limited and/or questionable efficacy. Thus, research and development of more effective mood stabilizer drugs is a leading challenge for modern psychopharmacology. We have demonstrated that 21 d administration of imipramine causes a behavioural syndrome similar to a cycle of bipolar disorder, i.e., a mania followed by a depression, in rats. Indeed, such treatment causes a behavioural supersensitivity to dopamine D2 receptor agonists associated with an increase sexual activity and aggressivity (mania). The dopamine receptor sensitization is followed, after imipramine discontinuation, by an opposite phenomenon (dopamine receptor desensitization) and an increased immobility time (depression) in the forced swimming test of depression. Memantine blocks the development of the supersensitivity and the ensuing desensitization associated with the depressive like behavior. On the basis of these observations we have suggested the use of memantine in the treatment of mania and in the prophylaxis of bipolar disorders. To test this hypothesis we performed several naturalistic studies that showed an acute antimanic effect and a long-lasting and progressive mood-stabilizing action (at least 3 years), without clinically relevant side effects. To confirm the observations of our naturalistic trials we are now performing a randomized controlled clinical trial. Finally we described the studies reporting the efficacy of memantine in manic-like symptoms occurring in psychiatric disorders other than bipolar. Limitations: A randomized controlled

  1. Interstitial thermotherapy with bipolar electrosurgical devices

    Science.gov (United States)

    Desinger, Kai; Stein, Thomas; Boehme, A.; Mack, Martin G.; Mueller, Gerhard J.

    1998-01-01

    In addition to the laser, microwave or other energy sources, interstitial thermotherapy with radio-frequency current (RFITT) in bipolar technique has already been shown in vitro to be a safe and economical alternative energy source with a comparable operating performance. The bipolar technique is, from the technical point of view, completely without risk whereas with monopolar devices, where a neutral electrode has to be applied, an uncontrolled current flow passes through the patient's body. The therapeutical application efficiency of these bipolar RF-needle applicators was evaluated using newly designed high performance flushed and cooled probes (qq 3 mm). These can be used to create large coagulation volumes in tissue such as for the palliative treatment of liver metastases or the therapy of the benign prostate hyperplasia. As a result, the achievable lesion size resulting from these flushed and internally cooled RF- probes could be increased by a factor of three compared to a standard bipolar probe. With these bipolar power RF- applicators, coagulation dimensions of 5 cm length and 4 cm diameter with a power input of 40 watt could be achieved within 20 minutes. No carbonization and electrode tissue adherence was found. Investigations in vitro with adapted RFITT-probes using paramagnetic materials such as titanium alloys and high performance plastic have shown that monitoring under MRI (Siemens Magnetom, 1.5 Tesla), allows visualization of the development of the spatial temperature distribution in tissue using an intermittent diagnostic and therapeutical application. This does not lead to a loss in performance compared to continuous application. A ratio of 1:4 (15 s Thermo Flash MRI, 60 s RF-energy) has shown to be feasible.

  2. Enhancement of the crystalline Ge film growth by inductively coupled plasma-assisted pulsed DC sputtering.

    Science.gov (United States)

    Kim, Eunkyeom; Han, Seung-Hee

    2014-11-01

    The effect of pulsed DC sputtering on the crystalline growth of Ge thin film was investigated. Ge thin films were deposited on the glass substrates using ICP-assisted pulsed DC sputtering. The Ge target was sputtered using asymmetric bipolar pulsed DC sputtering system with and without assistance of ICP source. The pulse frequency of 200 Hz and the pulse on time of 500 μsec (duty cycle = 10%) were kept during sputtering process. Crystal structures were studied from X-ray diffraction. The X-ray diffraction patterns clearly showed crystalline film structures. The Ge thin films with randomly oriented crystalline were obtained using pulsed DC sputtering without ICP, whereas they had well aligned (220) orientation crystalline using ICP source. Moreover, the combination of ICP assistance and pulsed DC sputtering enhanced the growth of crystalline Ge thin films without hydrogen and metal by in situ deposition. The structure and lattice of the films were studied from TEM images. The cross-sectional TEM images revealed the deposited Ge films with columnar structure.

  3. Effect of Annealing Temperature on the Microstructure and Resistivity of Ge2Sb2Te5 Films

    Institute of Scientific and Technical Information of China (English)

    LIU Bo; SONG Zhi-Tang; FENG Song-Lin; CHEN Bomy

    2004-01-01

    @@ The effect of annealing temperature on crystallization of amorphous Ge2Sb2 Te5 films with thickness of 40 nm is studied by TEM and AFM methods. The relationship between microstructure and resistivity of the Ge2Sb2 Te5film is investigated. From the TEM measurements, the grain size of crystallites increases gradually as the annealing temperature increases. When the annealing temperature is too high, voids are formed, which may originate from evaporation of the Ge2Sb2 Te5 film at the elevated temperatures, formation of sink, being nucleated by residual vacancies, and surface roughness. The resistivity of the Ge2Sb2 Te5 film decreases with the increasing annealing temperature and has slight changes when the temperature is higher than 400 ℃. Phase transitions and scattering of crystallite boundaries may be the major factors affecting the resistivity of the Ge2Sb2 Te5 film.

  4. Grayscale image recording on Ge2Sb2Te5 thin films through laser-induced structural evolution

    Science.gov (United States)

    Wei, Tao; Wei, Jingsong; Zhang, Kui; Zhao, Hongxia; Zhang, Long

    2017-02-01

    Chalcogenide Ge2Sb2Te5 thin films have been widely exploited as binary bit recording materials in optical and non-volatile electronic information storage, where the crystalline and amorphous states are marked as the information bits “0” and “1”, respectively. In this work, we demonstrate the use of Ge2Sb2Te5 thin films as multi-level grayscale image recording materials. High-resolution grayscale images are recorded on Ge2Sb2Te5 thin films through taking advantage of laser-induced structural evolution characteristic. Experimental results indicate that the change of laser energy results in the structural evolution of Ge2Sb2Te5 thin films. The structural evolution induces the difference of electronic polarizability and reflectivity, and high-resolution grayscale images are recorded on Ge2Sb2Te5 thin films through direct laser writing method, accordingly.

  5. Grayscale image recording on Ge2Sb2Te5 thin films through laser-induced structural evolution

    Science.gov (United States)

    Wei, Tao; Wei, Jingsong; Zhang, Kui; Zhao, Hongxia; Zhang, Long

    2017-01-01

    Chalcogenide Ge2Sb2Te5 thin films have been widely exploited as binary bit recording materials in optical and non-volatile electronic information storage, where the crystalline and amorphous states are marked as the information bits “0” and “1”, respectively. In this work, we demonstrate the use of Ge2Sb2Te5 thin films as multi-level grayscale image recording materials. High-resolution grayscale images are recorded on Ge2Sb2Te5 thin films through taking advantage of laser-induced structural evolution characteristic. Experimental results indicate that the change of laser energy results in the structural evolution of Ge2Sb2Te5 thin films. The structural evolution induces the difference of electronic polarizability and reflectivity, and high-resolution grayscale images are recorded on Ge2Sb2Te5 thin films through direct laser writing method, accordingly. PMID:28195209

  6. Grayscale image recording on Ge2Sb2Te5 thin films through laser-induced structural evolution.

    Science.gov (United States)

    Wei, Tao; Wei, Jingsong; Zhang, Kui; Zhao, Hongxia; Zhang, Long

    2017-02-14

    Chalcogenide Ge2Sb2Te5 thin films have been widely exploited as binary bit recording materials in optical and non-volatile electronic information storage, where the crystalline and amorphous states are marked as the information bits "0" and "1", respectively. In this work, we demonstrate the use of Ge2Sb2Te5 thin films as multi-level grayscale image recording materials. High-resolution grayscale images are recorded on Ge2Sb2Te5 thin films through taking advantage of laser-induced structural evolution characteristic. Experimental results indicate that the change of laser energy results in the structural evolution of Ge2Sb2Te5 thin films. The structural evolution induces the difference of electronic polarizability and reflectivity, and high-resolution grayscale images are recorded on Ge2Sb2Te5 thin films through direct laser writing method, accordingly.

  7. RBS-study of GexSi1-x Compounds Formed by Variable Dose Ge Implantation into Si Wafers

    Directory of Open Access Journals (Sweden)

    Ramírez A.

    2002-01-01

    Full Text Available Amorphous and relaxed epitaxial GeSi films are prepared by Ge-implantation into Si(111 wafers of both 60 keV and 200 keV energetic Ge+-ions with appropriate dose, followed by post-implantation thermal annealing, comprising a single final annealing at a temperature of 900 °C. The implantation dose was varied between 10(14 and 10(17 atoms cm-2. Rutherford backscattering (RBS and channeling analysis was applied in order to explore the formation of a single crystalline Si-Ge compound layer, both prior and after the thermal treatment. The depth and the thickness of the implanted layer, as well as their molar composition and crystalline quality was determined, and it was found that a single crystalline Si-Ge alloy layer was created, with both depth and mole fraction depending on the ion energy and the ion dose.

  8. Microstructural analyses of amorphic diamond, i-C, and amorphous carbon

    DEFF Research Database (Denmark)

    Collins, C. B.; Davanloo, F.; Jander, D.R.;

    1992-01-01

    Recent experiments have identified the microstructure of amorphic diamond with a model of packed nodules of amorphous diamond expected theoretically. However, this success has left in doubt the relationship of amorphic diamond to other noncrystalline forms of carbon. This work reports...... the comparative examinations of the microstructures of samples of amorphic diamond, i-C, and amorphous carbon. Four distinct morphologies were found that correlated closely with the energy densities used in preparing the different materials. Journal of Applied Physics is copyrighted by The American Institute...

  9. A global Ge isotope budget

    Science.gov (United States)

    Baronas, J. Jotautas; Hammond, Douglas E.; McManus, James; Wheat, C. Geoffrey; Siebert, Christopher

    2017-04-01

    We present measurements of Ge isotope composition and ancillary data for samples of river water, low- and high-temperature hydrothermal fluids, and seawater. The dissolved δ74Ge composition of analyzed rivers ranges from 2.0 to 5.6‰, which is significantly heavier than previously determined values for silicate rocks (δ74Ge = 0.4-0.7‰, Escoube et al., Geostand. Geoanal. Res., 36(2), 2012) from which dissolved Ge is primarily derived. An observed negative correlation between riverine Ge/Si and δ74Ge signatures suggests that the primary δ74Ge fractionation mechanism during rock weathering is the preferential incorporation of light isotopes into secondary weathering products. High temperature (>150 °C) hydrothermal fluids analyzed in this study have δ74Ge of 0.7-1.6‰, most likely fractionated during fluid equilibration with quartz in the reaction zone. Low temperature (25-63 °C) hydrothermal fluids are heavier (δ74Ge between 2.9‰ and 4.1‰) and most likely fractionated during Ge precipitation with hydrothermal clays. Seawater from the open ocean has a δ74Gesw value of 3.2 ± 0.4‰, and is indistinguishable among the different ocean basins at the current level of precision. This value should be regulated over time by the isotopic balance of Ge sources and sinks, and a new compilation of these fluxes is presented, along with their estimated isotopic compositions. Assuming steady-state, non-opal Ge sequestration during sediment authigenesis likely involves isotopic fractionation Δ74Gesolid-solution that is -0.6 ± 1.8‰.

  10. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    2004-01-01

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio and...

  11. Photoexcitation-induced processes in amorphous semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jai [School of Engineering and Logistics, Charles Darwin University, Darwin, NT 0909 (Australia)]. E-mail: jai.singh@cdu.edu.au

    2005-07-30

    Theories for the mechanism of photo-induced processes of photodarkening (PD), volume expansion (VE) in amorphous chalcogenides are presented. Rates of spontaneous emission of photons by radiative recombination of excitons in amorphous semiconductors are also calculated and applied to study the excitonic photoluminescence in a-Si:H. Results are compared with previous theories.

  12. Band Gaps of an Amorphous Photonic Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Yi-Quan; FENG Zhi-Fang; HU Xiao-Yong; CHENG Bing-Ying; ZHANG Dao-Zhong

    2004-01-01

    @@ A new kind of amorphous photonic materials is presented. Both the simulated and experimental results show that although the disorder of the whole dielectric structure is strong, the amorphous photonic materials have two photonic gaps. This confirms that the short-range order is an essential factor for the formation of the photonic gaps.

  13. Co amorphous systems: A product development perspective.

    Science.gov (United States)

    Chavan, Rahul B; Thipparaboina, Rajesh; Kumar, Dinesh; Shastri, Nalini R

    2016-12-30

    Solubility is one of the major problems associated with most of the new chemical entities that can be reasonably addressed by drug amorphization. However, being a high-energy form, it usually tends to re-crystallize, necessitating new formulation strategies to stabilize amorphous drugs. Polymeric amorphous solid dispersion (PASD) is one of the widely investigated strategies to stabilize amorphous drug, with major limitations like limited polymer solubility and hygroscopicity. Co amorphous system (CAM), a new entrant in amorphous arena is a promising alternative to PASD. CAMs are multi component single phase amorphous solid systems made up of two or more small molecules that may be a combination of drugs or drug and excipients. Excipients explored for CAM preparation include amino acids, carboxylic acids, nicotinamide and saccharine. Advantages offered by CAM include improved aqueous solubility and physical stability of amorphous drug, with a potential to improve therapeutic efficacy. This review attempts to address different aspects in the development of CAM as drug products. Criterion for co-former selection, various methods involved in CAM preparation, characterization tools, stability, scale up and regulatory requirements for the CAM product development are discussed.

  14. Electron beam recrystallization of amorphous semiconductor materials

    Science.gov (United States)

    Evans, J. C., Jr.

    1968-01-01

    Nucleation and growth of crystalline films of silicon, germanium, and cadmium sulfide on substrates of plastic and glass were investigated. Amorphous films of germanium, silicon, and cadmium sulfide on amorphous substrates of glass and plastic were converted to the crystalline condition by electron bombardment.

  15. Photoluminescence enhancement through vertical stacking of defect-engineered Ge on Si quantum dots

    Science.gov (United States)

    Groiss, Heiko; Spindlberger, Lukas; Oberhumer, Peter; Schäffler, Friedrich; Fromherz, Thomas; Grydlik, Martyna; Brehm, Moritz

    2017-02-01

    In this work, we show that the room-temperature photoluminescence intensity from Ge ion-bombarded (GIB) epitaxial Ge on Si quantum dots (QD) can be improved by their vertical stacking. We stress that the growth of GIB-QD multilayers is more demanding compared to all-crystalline epitaxial QDs, as a consequence of local amorphous regions within the GIB-QDs required during their genesis. We show that in spite of those amorphous regions, for accurately chosen growth temperatures of the Si spacer layers separating the GIB-QD layers, multiple GIB-QD layers can be stacked without detrimental break-down of epitaxial growth. Compared to a single GIB-QD layer, we observe a 650% increase in PL intensity for an eleven-layer GIB-QD stack, indicating that such multilayers are promising candidates as gain material for all-group-IV nano-photonic lasers.

  16. Neutron irradiation induced amorphization of silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Snead, L.L.; Hay, J.C. [Oak Ridge National Lab., TN (United States)

    1998-09-01

    This paper provides the first known observation of silicon carbide fully amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60 C to a total fast neutron fluence of 2.6 {times} 10{sup 25} n/m{sup 2}. Amorphization was seen in both materials, as evidenced by TEM, electron diffraction, and x-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density ({minus}10.8%), elastic modulus as measured using a nanoindentation technique ({minus}45%), hardness as measured by nanoindentation ({minus}45%), and standard Vickers hardness ({minus}24%). Similar property changes are observed for the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than 130 C.

  17. Tritiated amorphous silicon for micropower applications

    Energy Technology Data Exchange (ETDEWEB)

    Kherani, N.P. [Ontario Hydro Technologies, Toronto, Ontario (Canada)]|[Univ. of Toronto, Ontario (Canada); Kosteski, T.; Zukotynski, S. [Univ. of Toronto, Ontario (Canada); Shmayda, W.T. [Ontario Hydro Technologies, Toronto, Ontario (Canada)

    1995-10-01

    The application of tritiated amorphous silicon as an intrinsic energy conversion semiconductor for radioluminescent structures and betavoltaic devices is presented. Theoretical analysis of the betavoltaic application shows an overall efficiency of 18% for tritiated amorphous silicon. This is equivalent to a 330 Ci intrinsic betavoltaic device producing 1 mW of power for 12 years. Photoluminescence studies of hydrogenated amorphous silicon, a-Si:H, show emission in the infra-red with a maximum quantum efficiency of 7.2% at 50 K; this value drops by 3 orders of magnitude at a temperature of 300 K. Similar studies of hydrogenated amorphous carbon show emission in the visible with an estimated quantum efficiency of 1% at 300 K. These results suggest that tritiated amorphous carbon may be the more promising candidate for room temperature radioluminescence in the visible. 18 refs., 5 figs.

  18. Amorphous metals for radial airgap electric machines

    Energy Technology Data Exchange (ETDEWEB)

    Lu Ning; Kokernak, J.M. [Rensselaer Polytechnic Institute, Dept. of Electric Poer Engineering, Troy, NY (United States)

    2000-08-01

    Amorphous steel teas been in use for some time in the transformer industry. The difficulty associated with handling such a hard material paired with the extremely thin nature of the casting has prevented amorphous steel from being seriously considered for radial airgap electric motors. In light of recent advances in manufacturing and handling of the amorphous materials, this paper presents an investigation into the performance advantages of an amorphous brushless dc motor. A two-dimensional, time-stepped, finite element model is used to analyze the electromagnetic field and motor performance for an amorphous brushless dc (BLDC) motor and a M-l9 BLDC motor. Each is modeled with identical structure geometries. Magnetic core losses are also estimated for the two motors operating over a frequency range of 50 to 200 Hz. (orig.)

  19. EXAFS characterization of amorphous GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Ridgway, M.C.; Glover, C.J. [Australia National Univ., Canberra (Australia); Foran, G.J. [Australian Nuclear Science and Technology Organization, Menai (Australia); Yu, K.M. [Lawrence Berkeley National Lab., CA (United States). Materials Sciences Div.

    1998-12-31

    The structural parameters of stoichiometric, amorphous GaAs have been determined with extended x-ray absorption fine structure (EXAFS) measurements performed in transmission mode at 10 K. Amorphous GaAs samples were fabricated with a combination of epitaxial growth, ion implantation and selective chemical etching. Relative to a crystalline sample, the nearest-neighbor bond length and Debye-Waller factor both increased for amorphous material. In contrast, the coordination numbers about both Ga and As atoms in the amorphous phase decreased to {approximately} 3.85 atoms from the crystalline value of four. All structural parameters were independent of implantation conditions and as a consequence, were considered representative of intrinsic, amorphous GaAs as opposed to an implantation-induced extrinsic structure.

  20. Solid-state diffusion in amorphous zirconolite

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.; Dove, M. T.; Trachenko, K. [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Zarkadoula, E. [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6138 (United States); Todorov, I. T. [STFC Daresbury Laboratory, Warrington WA4 1EP (United Kingdom); Geisler, T. [Steinmann-Institut für Geologie, Mineralogie und Paläontologie, University of Bonn, D-53115 Bonn (Germany); Brazhkin, V. V. [Institute for High Pressure Physics, RAS, 142190 Moscow (Russian Federation)

    2014-11-14

    We discuss how structural disorder and amorphization affect solid-state diffusion, and consider zirconolite as a currently important case study. By performing extensive molecular dynamics simulations, we disentangle the effects of amorphization and density, and show that a profound increase of solid-state diffusion takes place as a result of amorphization. Importantly, this can take place at the same density as in the crystal, representing an interesting general insight regarding solid-state diffusion. We find that decreasing the density in the amorphous system increases pre-factors of diffusion constants, but does not change the activation energy in the density range considered. We also find that atomic species in zirconolite are affected differently by amorphization and density change. Our microscopic insights are relevant for understanding how solid-state diffusion changes due to disorder and for building predictive models of operation of materials to be used to encapsulate nuclear waste.

  1. Drug-excipient behavior in polymeric amorphous solid dispersions.

    OpenAIRE

    Surikutchi Bhanu Teja; Shashank Pralhad Patil; Ganesh Shete; Sarsvatkumar Patel; Arvind Kumar Bansal

    2016-01-01

    Amorphous drug delivery systems are increasingly utilized to enhance aqueous solubility and oral bioavailability. However, they lack physical and/or chemical stability. One of the most common ways of stabilizing an amorphous form is by formulating it as an amorphous solid dispersion. This review focuses on polymeric amorphous solid dispersions wherein polymers are used as excipients to stabilize the amorphous form. A brief introduction to the basic concepts of amorphous systems such as glass ...

  2. Drug excipient behavior in polymeric amorphous solid dispersions

    OpenAIRE

    Bhanu Teja Surikutchi; Shashank Pralhad Patil; Ganesh Shete; Sarsvatkumar Patel; Arvind Kumar Bansal

    2013-01-01

    Amorphous drug delivery system is being increasingly utilized for enhancing aqueous solubility and oral bioavailability. However it suffers from lack of physical/chemical stability. One of the most common ways of stabilizing an amorphous form is by formulating it as amorphous solid dispersion. This review focuses on the polymeric amorphous solid dispersion wherein polymers are used as excipients to stabilize the amorphous form. We present a brief introduction of basic concepts of amorphous sy...

  3. Microstructure and Mechanical Properties of Heat-treated GeSb2Te4 Thin Films

    Institute of Scientific and Technical Information of China (English)

    DING Jianning; XIE Guoxin; FAN Zhen; FU Yongzhong; LING Zhiyong

    2007-01-01

    The effect of annealing on microstructure, adhesive and frictional properties of GeSb2Te4 films were experimentally studied. The GeSb2Te4 films were prepared by radio frequency (RF) magnetron sputtering, and annealed at 200℃ and 340℃ under vacuum circumstance, respectively. The adhesion and friction experiments were mainly conducted with a lateral force microscope (LFM) for the GeSb2Te4 thin films before and after annealing. Their morphology and phase structure were analyzed by using atomic force microscopy (AFM) and X-ray Diffraction (XRD) techniques, and the nanoindention was employed to evaluate their hardness values. Moreover, an electric force microscope (EFM) was used to measure the surface potential. It is found that the deposited GeSb2Te4 thin film undergoes an amorphous-to-fcc and fcc-to-hex structure transition; the adhesion has a weaker dependence on the surface roughness, but a certain correlation with the surface potential of GeSb2Te4 thin films. And the friction behavior of GeSb2Te4 thin films follows their adhesion behavior under a lower applied load. However, such a relation is replaced by the mechanical behavior when the load is relatively higher. Moreover, the GeSb2Te4 thin film annealed at 340℃ presents a lubricative property.

  4. Lattice Thermal Conductivity of the Binary and Ternary Group-IV Alloys Si-Sn, Ge-Sn, and Si-Ge-Sn

    Science.gov (United States)

    Khatami, S. N.; Aksamija, Z.

    2016-07-01

    Efficient thermoelectric (TE) energy conversion requires materials with low thermal conductivity and good electronic properties. Si-Ge alloys, and their nanostructures such as thin films and nanowires, have been extensively studied for TE applications; other group-IV alloys, including those containing Sn, have not been given as much attention as TEs, despite their increasing applications in other areas including optoelectronics. We study the lattice thermal conductivity of binary (Si-Sn and Ge-Sn) and ternary (Si-Ge-Sn) alloys and their thin films in the Boltzmann transport formalisms, including a full phonon dispersion and momentum-dependent boundary-roughness scattering. We show that Si-Sn alloys have the lowest conductivity (3 W /mK ) of all the bulk alloys, more than 2 times lower than Si-Ge, attributed to the larger difference in mass between the two constituents. In addition, we demonstrate that thin films offer an additional reduction in thermal conductivity, reaching around 1 W /mK in 20-nm-thick Si-Sn, Ge-Sn, and ternary Si-Ge-Sn films, which is near the conductivity of amorphous SiO2 . We conclude that group-IV alloys containing Sn have the potential for high-efficiency TE energy conversion.

  5. Comparison of thermal stabilities between Zr9(Ge2Sb2Te5)91 and Ge2Sb2Te5 phase change films

    Science.gov (United States)

    Li, Zengguang; Lu, Yegang; Ma, Yadong; Song, Sannian; Shen, Xiang; Wang, Guoxiang; Dai, Shixun; Song, Zhitang

    2016-10-01

    Phase change memory is regarded as one of the most promising candidates for the next-generation non-volatile memory. Zr9(Ge2Sb2Te5)91 film was investigated as storage material for phase-change memory application. The crystallization temperature (Tc) and 10 years data retention temperature of the Zr9(Ge2Sb2Te5)91 film are about 195 and 106.7°C, respectively, and both higher than that of Ge2Sb2Te5 (GST). The sheet resistance ratio between amorphous and crystalline states is up to four orders of magnitude. The crystalline resistance of Zr9(Ge2Sb2Te5)91 film is higher than GST for one order of magnitude, which contribute to reduce the power consumption for PCM device. Zr9(Ge2Sb2Te5)91 film exhibit larger optical band gap in comparison with GST. Zr9(Ge2Sb2Te5)91 is considered to be a promising material for phase change memory.

  6. Ge/SiGe superlattices for nanostructured thermoelectric modules

    Energy Technology Data Exchange (ETDEWEB)

    Chrastina, D., E-mail: daniel@chrastina.net [L-NESS Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy); Cecchi, S. [L-NESS Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy); Hague, J.P. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA (United Kingdom); Frigerio, J. [L-NESS Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy); Samarelli, A.; Ferre–Llin, L.; Paul, D.J. [School of Engineering, University of Glasgow, Oakfield Avenue, Glasgow, G12 8LT (United Kingdom); Müller, E. [Electron Microscopy ETH Zurich (EMEZ), ETH-Zürich, CH-8093 (Switzerland); Etzelstorfer, T.; Stangl, J. [Institut für Halbleiter und Festkörperphysik, Universität Linz, A-4040 Linz (Austria); Isella, G. [L-NESS Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy)

    2013-09-30

    Thermoelectrics are presently used in a number of applications for both turning heat into electricity and also for using electricity to produce cooling. Mature Si/SiGe and Ge/SiGe heteroepitaxial growth technology would allow highly efficient thermoelectric materials to be engineered, which would be compatible and integrable with complementary metal oxide silicon micropower circuits used in autonomous systems. A high thermoelectric figure of merit requires that electrical conductivity be maintained while thermal conductivity is reduced; thermoelectric figures of merit can be improved with respect to bulk thermoelectric materials by fabricating low-dimensional structures which enhance the density of states near the Fermi level and through phonon scattering at heterointerfaces. We have grown and characterized Ge-rich Ge/SiGe/Si superlattices for nanofabricated thermoelectric generators. Low-energy plasma-enhanced chemical vapor deposition has been used to obtain nanoscale-heterostructured material which is several microns thick. Crystal quality and strain control have been investigated by means of high resolution X-ray diffraction. High-resolution transmission electron microscopy images confirm the material and interface quality. Electrical conductivity has been characterized by the mobility spectrum technique. - Highlights: ► High-quality Ge/SiGe multiple quantum wells for thermoelectric applications ► Mobility spectra of systems featuring a large number of parallel conduction channels ► Competitive thermoelectric properties measured in single devices.

  7. Growth of Ge nanofilms using electrochemical atomic layer deposition, with a "bait and switch" surface-limited reaction.

    Science.gov (United States)

    Liang, Xuehai; Zhang, Qinghui; Lay, Marcus D; Stickney, John L

    2011-06-01

    Ge nanofilms were deposited from aqueous solutions using the electrochemical analog of atomic layer deposition (ALD). Direct electrodeposition of Ge from an aqueous solution is self-limited to a few monolayers, depending on the pH. This report describes an E-ALD process for the growth of Ge films from aqueous solutions. The E-ALD cycle involved inducing a Ge atomic layer to deposit on a Te atomic layer formed on Ge, via underpotential deposition (UPD). The Te atomic layer was then reductively stripped from the deposit, leaving the Ge and completing the cycle. The Te atomic layer was bait for Ge deposition, after which the Te was switched out, reduced to a soluble telluride, leaving the Ge (one "bait and switch" cycle). Deposit thickness was a linear function of the number of cycles. Raman spectra indicated formation of an amorphous Ge film, consistent with the absence of a XRD pattern. Films were more stable and homogeneous when formed on Cu substrates, than on Au, due to a larger hydrogen overpotential, and the corresponding lower tendency to form bubbles.

  8. Systematic review of the prevalence of bipolar disorder and bipolar spectrum disorders in population-based studies

    Directory of Open Access Journals (Sweden)

    José Caetano Dell'Aglio Jr.

    2013-01-01

    Full Text Available This paper describes the findings of a systematic literature review aimed at providing an overview of the lifetime prevalence of bipolar disorder and bipolar spectrum disorders in population-based studies. Databases MEDLINE, ProQuest, Psychnet, and Web of Science were browsed for papers published in English between 1999 and May 2012 using the following search string: bipolar disorders OR bipolar spectrum disorders AND prevalence OR cross-sectional OR epidemiology AND population-based OR non-clinical OR community based. The search yielded a total of 434 papers, but only those published in peer-reviewed journals and with samples aged ≥ 18 years were included, resulting in a final sample of 18 papers. Results revealed rather heterogeneous findings concerning the prevalence of bipolar disorders and bipolar spectrum disorders. Lifetime prevalence of bipolar disorder ranged from 0.1 to 7.5%, whereas lifetime prevalence of bipolar spectrum disorders ranged from 2.4 to 15.1%. Differences in the rates of bipolar disorder and bipolar spectrum disorders may be related to the consideration of subthreshold criteria upon diagnosis. Differences in the prevalence of different subtypes of the disorder are discussed in light of diagnostic criteria and instruments applied.

  9. Mapping of GeSbTe Thin Film Electrical Properties with Conductive AFM

    Science.gov (United States)

    Brocious, Jordan; Inglefield, Colin; Bobela, David; Herring, Thomas; Taylor, P. Craig

    2007-10-01

    The phase-change material system GeSbTe (GST) is currently used for optical data storage, however many details of the mechanism governing the phase change are not understood. GST's optical properties and electrical conductivities differ between the amorphous and crystalline phases. For instance, the electrical conductivity in the amorphous phase can be ˜10^3 times smaller than electrical conductivity in the crystalline phase. Thin films of Ge2Sb2Te5 and other alloys were created by a RF sputtering technique, which is known to produce amorphous samples. Crystalline regions were created after growth by localized laser heating. We characterized these films with Conductive Atomic Force Microscopy, which provides physical and electrical topography images. From this characterization we have identified sparse ˜100 nm highly conductive regions in the overall low-conductivity amorphous material. Although the laser treatment does not result in a uniformly conductive film, conductive regions in the treated material are significantly denser and larger.

  10. Bipolar zinc/oxygen battery development

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Schlatter, C. [Swiss Federal Inst. of Technology, Lausanne (Switzerland)

    1997-06-01

    A bipolar electrically rechargeable Zn/O{sub 2} battery has been developed. Reticulated copper foam served as substrate for the zinc deposit on the anodic side, and La{sub 0.6}Ca{sub 0.4}CoO{sub 3}-catalyzed bifunctional oxygen electrodes were used on the cathodic side of the cells. The 100 cm{sup 2} unit cell had an open circuit voltage of 1,4 V(O{sub 2}) in moderately alkaline electrolyte. The open circuit voltage and the peak power measured for a stack containing seven cells were ca. 10V and 90W, respectively. The current-potential behaviour was determined as a function of the number of bipolar cells, and the maximum discharge capacity was determined at different discharge rates. (author) 4 figs., 1 ref.

  11. Comorbidity of Asperger's syndrome and Bipolar disorder

    Directory of Open Access Journals (Sweden)

    Azzoni Antonella

    2008-11-01

    Full Text Available Abstract Background and objective Asperger's Syndrome (AS is a pervasive developmental disorder that is sometimes unrecognized, especially in the adult psychiatric setting. On the other hand, in patients with an AS diagnosis, comorbid psychiatric disorders may be unrecognized in the juvenile setting. The aim of the paper is to show and discuss some troublesome and complex problems of the management of patients with AS and comorbid Bipolar Disorder (BD. Methods The paper describes three patients affected by AS and bipolar spectrum disorders. Results and conclusion Mood stabilizers and 2nd generation antipsychotics were effective in the treatment of these AS patients with comorbid BD, while the use of antidepressants was associated with worsening of the mood disorder. It is of importance to recognize both the psychiatric diagnoses in order to arrange an exhaustive therapeutic program and to define specific and realistic goals of treatment.

  12. Dissecting bipolar disorder complexity through epigenomic approach

    Science.gov (United States)

    Ludwig, B; Dwivedi, Y

    2016-01-01

    In recent years, numerous studies of gene regulation mechanisms have emerged in neuroscience. Epigenetic modifications, described as heritable but reversible changes, include DNA methylation, DNA hydroxymethylation, histone modifications and noncoding RNAs. The pathogenesis of psychiatric disorders, such as bipolar disorder, may be ascribed to a complex gene–environment interaction (G × E) model, linking the genome, environmental factors and epigenetic marks. Both the high complexity and the high heritability of bipolar disorder make it a compelling candidate for neurobiological analyses beyond DNA sequencing. Questions that are being raised in this review are the precise phenotype of the disorder in question, and also the trait versus state debate and how these concepts are being implemented in a variety of study designs. PMID:27480490

  13. Udvikling af medicinsk behandling mod bipolar lidelse

    DEFF Research Database (Denmark)

    Ellegaard, Pernille Kempel

    2015-01-01

    Selvom Esbjerg ligger i vandkants Danmark, er det den Psykiatriske Forskningsenhed i denne by, der er primus motor for et stort forsøg blandt mennesker, der lider af bipolar lidelse. Forsøget hedder ”NACOS”, og er et medicinsk forsøg til mennesker, der befinder sig i den depressive fase.......Selvom Esbjerg ligger i vandkants Danmark, er det den Psykiatriske Forskningsenhed i denne by, der er primus motor for et stort forsøg blandt mennesker, der lider af bipolar lidelse. Forsøget hedder ”NACOS”, og er et medicinsk forsøg til mennesker, der befinder sig i den depressive fase....

  14. Chronobiology of bipolar disorder: therapeutic implication.

    Science.gov (United States)

    Dallaspezia, Sara; Benedetti, Francesco

    2015-08-01

    Multiple lines of evidence suggest that psychopathological symptoms of bipolar disorder arise in part from a malfunction of the circadian system, linking the disease with an abnormal internal timing. Alterations in circadian rhythms and sleep are core elements in the disorders, characterizing both mania and depression and having recently been shown during euthymia. Several human genetic studies have implicated specific genes that make up the genesis of circadian rhythms in the manifestation of mood disorders with polymorphisms in molecular clock genes not only showing an association with the disorder but having also been linked to its phenotypic particularities. Many medications used to treat the disorder, such as antidepressant and mood stabilizers, affect the circadian clock. Finally, circadian rhythms and sleep researches have been the starting point of the developing of chronobiological therapies. These interventions are safe, rapid and effective and they should be considered first-line strategies for bipolar depression.

  15. Isospin structure in 68Ge

    Institute of Scientific and Technical Information of China (English)

    BAI Hong-Bo; DONG Hong-Fei; ZHANG Jin-Fu; LU Li-Jun; CAO Wan-Cang; LI Xiao-Wei; WANg Yin

    2009-01-01

    The interacting boson model-3(IBM-3) has been used to study the low-energy level structure and electromagnetic transitions of 68Ge nucleus. The main components of the wave function for some states are also analyzed respectively. The theoretical calculations are in agreement with experimental data, and the 68Ge is in transition from U(5) to SU(3).

  16. A positron source using an axially oriented crystal associated to a granular amorphous converter

    Institute of Scientific and Technical Information of China (English)

    XU Cheng-Hai; Robert Chehab; Peter Sievers; Xavier Artru; Michel Chevallier; Olivier Dadoun; PEI Guo-Xi; Vladimir M. Strakhovenko; Alessandro Variola

    2012-01-01

    A non-conventional positron source using the intense γ radiation from an axially oriented monocrystal which materializes into e+e- pairs in a granular amorphous converter is described.The enhancement of photon radiation by multi-GeV electrons crossing a tungsten crystal along its 〈111〉 axis is reported.The resulting enhancement of pair production in an amorphous converter placed 2 meters downstream,is also reported.Sweeping off the charged particles from the crystal by a bending magnet upstream of the converter allows a significant reduction of the deposited energy density.Substituting a granular target made of small spheres for the usual compact one,makes the energy dissipation easier.The deposited energy and corresponding heating are analyzed and solutions for cooling are proposed.The configurations studied here for this kind of positron source allow its consideration for unpolarized positrons for the ILC.

  17. Controllable crystallization and enhanced amorphous stability of Sb-Te films modified by Ag-doping

    Science.gov (United States)

    Zhong, Juechen; Luo, Yang; Gu, Ting; Wang, Zhenglai; Jiang, Kefeng; Wang, Guoxiang; Lu, Yegang

    2016-10-01

    Ag-doped Sb-Te films were deposited by magnetron co-sputtering and the structure, electrical, optical and thermal properties were analyzed. The results show that Ag-doping restrains crystal grain size, and changes a preferred orientation of the crystalline phase. The crystallization temperature is increased due to the Ag addition. Both amorphous resistance and crystalline resistance are enhanced and the resistance ratio reaches ˜104. Compared with Ge2Sb2Te5, Ag26.82(Sb3Te)73.18 film exhibits a better amorphous thermal stability, a higher crystallization temperature (˜166 °C), a wider optical band gap (0.515 eV), a larger crystallization activation energy (3.17 eV) as well as a better 10 years data retention at 92 °C.

  18. A positron source using an axially oriented crystal associated to a granular amorphous converter

    CERN Document Server

    Xu, Cheng-Hai; Sievers, Peter; Artru, Xavier; Chevallier, Michel; Dadoun, Olivier; Pei, Guo-Xi; Strakhovenko, Vladimir M; Variola, Alessandro

    2012-01-01

    A non-conventional positron source using the intense l radiation from an axially oriented monocrystal which materializes into e(+)e(-') pairs in a granular amorphous converter is described. The enhancement of photon radiation by multi-GeV electrons crossing a tungsten crystal along its axis is reported. The resulting enhancement of pair production in an amorphous converter placed 2 meters downstream, is also reported. Sweeping off the charged particles from the crystal by a bending magnet upstream of the converter allows a significant reduction of the deposited energy density. Substituting a granular target made of small spheres for the usual compact one, makes the energy dissipation easier. The deposited energy and corresponding heating are analyzed and solutions for cooling are proposed. The configurations studied here for this kind of positron source allow its consideration for unpolarized positrons for the ILC.

  19. High-frequency noise modeling of Si(Ge) bipolar transistors

    NARCIS (Netherlands)

    Vitale, F.

    2014-01-01

    The design and the optimization of electronic systems often requires a detailed knowledge of the inherent noise generated within semiconductor active devices, constituting the core of such systems. Examples of applications in which noise is a key issue include receiver front-ends in radiofrequency (

  20. Bipolar disorder, a precursor of Parkinson's disease?

    Directory of Open Access Journals (Sweden)

    Tânia M.S. Novaretti

    Full Text Available ABSTRACT Parkinson's disease is a neurodegenerative disorder predominantly resulting from dopamine depletion in the substantia nigra pars compacta. Some psychiatric disorders may have dopaminergic dysfunction as their substrate. We describe a well-documented case of Parkinson's disease associated with Bipolar Disorder. Although there is some knowledge about the association between these diseases, little is known about its pathophysiology and correlation. We believe that among various hypotheses, many neurotransmitters are linked to this pathophysiology.

  1. Bipolar Transistor Tester for Physics Lab

    CERN Document Server

    Baddi, Raju

    2012-01-01

    A very simple low cost bipolar transistor tester for physics lab is given. The proposed circuit not only indicates the type of transistor(NPN/PNP) but also indicates the terminals(emitter, base and collector) using simple dual colored(Red/Green) LEDs. Color diagrams of testing procedure have been given for easy following. This article describes the construction of this apparatus in all detail with schematic circuit diagram, circuit layout and constructional illustration.

  2. The Bipolar Quantum Drift-diffusion Model

    Institute of Scientific and Technical Information of China (English)

    Xiu Qing CHEN; Li CHEN

    2009-01-01

    A fourth order parabolic system, the bipolar quantum drift-diffusion model in semiconductor simulation, with physically motivated Dirichlet-Neumann boundary condition is studied in this paper. By semidiscretization in time and compactness argument, the global existence and semiclassical limit are obtained, in which semiclassical limit describes the relation between quantum and classical drift-diffusion models. Furthermore, in the case of constant doping, we prove the weak solution exponentially approaches its constant steady state as time increases to infinity.

  3. Complementary medicines in pediatric bipolar disorder.

    Science.gov (United States)

    Bogarapu, S; Bishop, J R; Krueger, C D; Pavuluri, M N

    2008-02-01

    The increasing number and availability of various complementary and alternative medicines (CAM) has resulted in an exponentially growing utilization of these products for everything from minor aches and pains to the treatment of mental illness. Difficulties in treating mental illnesses in children, averseness to having children take psychiatric medications, and stigma all drive patients and their families to research alternative treatments. As a result, there has been an increased utilization of CAM in psychiatry, particularly for hard to treat conditions like pediatric BD. It is important for the health care providers to be aware of the alternative treatments by some of their patients. A review of studies investigating the utility of complementary and alternative medicines in bipolar patients was conducted and selected studies were included. Omega-3 fatty acids and lecithin/ choline have preliminary data indicating potential utility in the CAM treatment for bipolar disorder while S-adenosyl methionine (SAM-e) and inositol have some data supporting their efficacy in the treatment of depressive symptoms. Some data for CAM suggest they may be useful adjunctive treatments but only little data are available to support their use as stand-alone therapy. Thus, the conventional medicines remain the first choice in pediatric bipolar management. Healthcare providers need to routinely inquire about the utilization of these treatments by their patients and become familiar with the risks and benefits involved with their use in children.

  4. Olanzapine discontinuation emergent recurrence in bipolar disorder

    Directory of Open Access Journals (Sweden)

    Manu Arora

    2014-01-01

    Full Text Available Objective: The efficacy of atypical antipsychotics including olanzapine in acute treatment of manic episode has been established, whereas its role in maintenance treatment is not clear. Materials and Methods: Thirteen patients of bipolar disorder who were on regular treatment with mood stabilizer and subsequently relapsed into mania or depressive episode after discontinuation of olanzapine were studied for various socio-demographic and clinical factors using retrospective chart review. Results: There was no correlation found between the period of tapering olanzapine, time to recurrence of episode after discontinuation, and the dosage of olanzapine at the time of discontinuation. The predominant early signs of relapse after discontinuation of olanzapine included sleep disturbance (72.7%, lack of insight for change in behavior (72.7%, irritability (54.5%, and elevated mood (45.5%. Conclusion: Mood stabilizer alone as a maintenance therapy of bipolar disorder may be inadequate for long-term management. A low dose of olanzapine along with mood stabilizers might be useful for prevention of recurrence in bipolar disorder.

  5. Bipolar outflows in OH/IR stars

    CERN Document Server

    Zijlstra, A A; Hekkert, P L; Likkel, L; Comeron, F; Norris, R P; Molster, F J; Cohen, R J; Zijlstra, Albert A.

    2000-01-01

    We investigate the development of bipolar outflows during the early post-AGB evolution. A sample of ten OH/IR stars is observed at high angular resolution, including bipolar nebulae (OH231.8+4.2), bright post-AGB stars (HD 101584) and reflection nebulae (e.g. Roberts 22). The IRAS colour--colour diagram separates the sample into different types of objects. One group may contain the progenitors to the (few) extreme bipolar planetary nebulae. Two objects show colours and chemistry very similar to the planetary nebulae with late IR-[WC] stars. One object is a confirmed close binary. A model is presented consisting of an outer AGB wind which is swept up by a faster post-AGB wind, with either wind being non-spherically symetric. The interface of the two winds is shown to exhibit a linear relation between velocity and distance from the star. The OH data confirms the predicted linear velocity gradients, and reveals torus-like, uniformly expanding components. All sources are discussed in detail using optical/HST imag...

  6. Historical Underpinnings of Bipolar Disorder Diagnostic Criteria.

    Science.gov (United States)

    Mason, Brittany L; Brown, E Sherwood; Croarkin, Paul E

    2016-07-15

    Mood is the changing expression of emotion and can be described as a spectrum. The outermost ends of this spectrum highlight two states, the lowest low, melancholia, and the highest high, mania. These mood extremes have been documented repeatedly in human history, being first systematically described by Hippocrates. Nineteenth century contemporaries Falret and Baillarger described two forms of an extreme mood disorder, with the validity and accuracy of both debated. Regardless, the concept of a cycling mood disease was accepted before the end of the 19th century. Kraepelin then described "manic depressive insanity" and presented his description of a full spectrum of mood dysfunction which could be exhibited through single episodes of mania or depression or a complement of many episodes of each. It was this concept which was incorporated into the first DSM and carried out until DSM-III, in which the description of episodic mood dysfunction was used to build a diagnosis of bipolar disorder. Criticism of this approach is explored through discussion of the bipolar spectrum concept and some recent examinations of the clinical validity of these DSM diagnoses are presented. The concept of bipolar disorder in children is also explored.

  7. Historical Underpinnings of Bipolar Disorder Diagnostic Criteria

    Directory of Open Access Journals (Sweden)

    Brittany L. Mason

    2016-07-01

    Full Text Available Mood is the changing expression of emotion and can be described as a spectrum. The outermost ends of this spectrum highlight two states, the lowest low, melancholia, and the highest high, mania. These mood extremes have been documented repeatedly in human history, being first systematically described by Hippocrates. Nineteenth century contemporaries Falret and Baillarger described two forms of an extreme mood disorder, with the validity and accuracy of both debated. Regardless, the concept of a cycling mood disease was accepted before the end of the 19th century. Kraepelin then described “manic depressive insanity” and presented his description of a full spectrum of mood dysfunction which could be exhibited through single episodes of mania or depression or a complement of many episodes of each. It was this concept which was incorporated into the first DSM and carried out until DSM-III, in which the description of episodic mood dysfunction was used to build a diagnosis of bipolar disorder. Criticism of this approach is explored through discussion of the bipolar spectrum concept and some recent examinations of the clinical validity of these DSM diagnoses are presented. The concept of bipolar disorder in children is also explored.

  8. Recurrence and Relapse in Bipolar Mood Disorder

    Directory of Open Access Journals (Sweden)

    S Gh Mousavi

    2004-06-01

    Full Text Available Background: Despite the effectiveness of pharmacotherapy in acute phase of bipolar mood disorder, patients often experience relapses or recurrent episodes. Hospitalization of patients need a great deal of financial and humanistic resources which can be saved through understanding more about the rate of relapse and factors affecting this rate. Methods: In a descriptive analytical study, 380 patients with bipolar disorder who were hospitalized in psychiatric emergency ward of Noor hospital, Isfahan, Iran, were followed. Each patient was considered for; the frequency of relapse and recurrence, kind of pharmachotherapy, presence of psychotherapeutic treatments, frequency of visits by psychiatrist and the rank of present episode. Results: The overall prevalence of recurrence was 42.2%. Recurrence was lower in patients using lithium carbonate or sodium valproate or combined therapy (about 40%, compared to those using carbamazepine (80%. Recurrence was higher in patients treated with only pharmacotherapy (44.5% compared to those treated with both pharmacotherapy and psychotherapy (22.2%. Patients who were visited monthy by psychiatrist had lower rate of recurrence compared to those who had irregular visits. Conclusion: The higher rate of recurrence observed in carbamazepine therapy may be due to its adverse reactions and consequently poor compliance to this drug. Lower rates of recurrence with psychotherapy and regular visits may be related to the preventive effects of these procedures and especially to the effective management of stress. Keywords: Bipolar Mood Disorder, Recurrence, Relapse.

  9. Historical Underpinnings of Bipolar Disorder Diagnostic Criteria

    Science.gov (United States)

    Mason, Brittany L.; Brown, E. Sherwood; Croarkin, Paul E.

    2016-01-01

    Mood is the changing expression of emotion and can be described as a spectrum. The outermost ends of this spectrum highlight two states, the lowest low, melancholia, and the highest high, mania. These mood extremes have been documented repeatedly in human history, being first systematically described by Hippocrates. Nineteenth century contemporaries Falret and Baillarger described two forms of an extreme mood disorder, with the validity and accuracy of both debated. Regardless, the concept of a cycling mood disease was accepted before the end of the 19th century. Kraepelin then described “manic depressive insanity” and presented his description of a full spectrum of mood dysfunction which could be exhibited through single episodes of mania or depression or a complement of many episodes of each. It was this concept which was incorporated into the first DSM and carried out until DSM-III, in which the description of episodic mood dysfunction was used to build a diagnosis of bipolar disorder. Criticism of this approach is explored through discussion of the bipolar spectrum concept and some recent examinations of the clinical validity of these DSM diagnoses are presented. The concept of bipolar disorder in children is also explored. PMID:27429010

  10. High rate lithium/thionyl chloride bipolar battery development

    Energy Technology Data Exchange (ETDEWEB)

    Russell, P.G. [Yardney Technical Products, Inc., Pawcatuck, CT (United States); Goebel, F. [Yardney Technical Products, Inc., Pawcatuck, CT (United States)

    1995-04-01

    The lithium/thionyl chloride (Li/SOCl{sub 2}) electrochemistry is capable of providing high power and high specific power, especially under pulse discharge conditions, when cells containing thin components are arranged in a bipolar configuration. This paper describes recent work concerned with bipolar cell design, cathode evaluation, component manufacturing methods, and the assembly and testing of bipolar modules containing up to 150 cells for Sonobuoy application. (orig.)

  11. High rate lithium-thionyl chloride bipolar battery development

    Energy Technology Data Exchange (ETDEWEB)

    Russell, P.G.; Goebel, F. [Yardney Technical Products, Inc., Pawcatuck, CT (United States)

    1994-12-31

    The lithium/thionyl chloride system is capable of providing both high power and high energy density when cells containing thin components are arranged in a bipolar configuration. Electrode current densities in excess of 300mA/cm{sup 2} are achieved during pulse discharge. The present work is concerned with bipolar cell design, cathode evaluation, component manufacturing methods, and the assembly and testing of bipolar modules containing up to 150 cells.

  12. High rate lithium/thionyl chloride bipolar battery development

    Science.gov (United States)

    Russell, P. G.; Goebel, F.

    The lithium/thionyl chloride ( {Li}/{SOCl2}) electrochemistry is capable of providing high power and high specific power, especially under pulse discharge conditions, when cells containing thin components are arranged in a bipolar configuration. This paper describes recent work concerned with bipolar cell design, cathode evaluation, component manufacturing methods, and the assembly and testing of bipolar modules containing up to 150 cells for Sonobuoy application.

  13. Bipolar disorder and metabolic syndrome: a systematic review

    OpenAIRE

    Letícia Czepielewski; Ledo Daruy Filho; Elisa Brietzke; Rodrigo Grassi-Oliveira

    2013-01-01

    OBJECTIVE: Summarize data on metabolic syndrome (MS) in bipolar disorder (BD). METHODS: A systematic review of the literature was conducted using the Medline, Embase and PsycInfo databases, using the keywords "metabolic syndrome", "insulin resistance" and "metabolic X syndrome" and cross-referencing them with "bipolar disorder" or "mania". The following types of publications were candidates for review: (i) clinical trials, (ii) studies involving patients diagnosed with bipolar disorder or (ii...

  14. Bipolarna motnja razpoloženja: Bipolar disorder:

    OpenAIRE

    Dernovšek, Mojca Zvezdana; Frangeš, Tadeja

    2013-01-01

    Bipolar disorder is very prevalent in general population. According to Diagnostic and statistical manual ofmental disorders, fourth revision - DSM-IV, four types ofbipolar disorder are distinguished: bipolar disorder 1, bipolar disorder II, cyclothymia, and other types (not specified otherwise). Etiology of disorder is multifactorial with overlap between genetic, environmental"and neurobiological factors. Due to complexity of clinical features it represents diagnostical and therapeutical chal...

  15. Effect of InP Doping on the Phase Transition of Thin GeSbTe Films

    Science.gov (United States)

    Bang, Ki Su; Oh, Yong Jun; Lee, Seung-Yun

    2015-08-01

    We report the crystallization and phase-transition behavior of GeSbTe thin films doped with indium phosphorus (InP). Pure GeSbTe thin films and InP-doped GeSbTe thin films were prepared by use of an rf magnetron sputtering method. After thermal annealing, electrical and optical changes in the thin films were observed. Sheet resistance and reflectance measurements revealed that InP doping suppresses crystallization of GeSbTe. X-ray diffraction analysis confirmed that addition of In and P atoms inhibits the phase transition from face-centered cubic to hexagonal closed-packed. Nucleation of the doped GeSbTe thin films was delayed at an annealing temperature of 100°C; after thermal annealing, neither segregation nor formation of a secondary phase occurred. These results indicate that InP doping improves the amorphous stability of GeSbTe thin films. It is believed this enhanced amorphous stability is a result of the formation of multiple, strong crosslinks by the In and P atoms.

  16. Birth of cone bipolar cells, but not rod bipolar cells, is associated with existing RGCs.

    Directory of Open Access Journals (Sweden)

    Ling Bai

    Full Text Available Retinal ganglion cells (RGCs play important roles in retinogenesis. They are required for normal retinal histogenesis and retinal cell number balance. Developmental RGC loss is typically characterized by initial retinal neuronal number imbalance and subsequent loss of retinal neurons. However, it is not clear whether loss of a specific non-RGC cell type in the RGC-depleted retina is due to reduced cell production or subsequent degeneration. Taking advantage of three knockout mice with varying degrees of RGC depletion, we re-examined bipolar cell production in these retinas from various aspects. Results show that generation of the cone bipolar cells is correlated with the existing number of RGCs. However, generation of the rod bipolar cells is unaffected by RGC shortage. Results report the first observation that RGCs selectively influence the genesis of subsequent retinal cell types.

  17. Birth of cone bipolar cells, but not rod bipolar cells, is associated with existing RGCs.

    Science.gov (United States)

    Bai, Ling; Kiyama, Takae; Li, Hongyan; Wang, Steven W

    2014-01-01

    Retinal ganglion cells (RGCs) play important roles in retinogenesis. They are required for normal retinal histogenesis and retinal cell number balance. Developmental RGC loss is typically characterized by initial retinal neuronal number imbalance and subsequent loss of retinal neurons. However, it is not clear whether loss of a specific non-RGC cell type in the RGC-depleted retina is due to reduced cell production or subsequent degeneration. Taking advantage of three knockout mice with varying degrees of RGC depletion, we re-examined bipolar cell production in these retinas from various aspects. Results show that generation of the cone bipolar cells is correlated with the existing number of RGCs. However, generation of the rod bipolar cells is unaffected by RGC shortage. Results report the first observation that RGCs selectively influence the genesis of subsequent retinal cell types.

  18. The Mood Disorder Questionnaire: A Simple, Patient-Rated Screening Instrument for Bipolar Disorder

    OpenAIRE

    Hirschfeld, Robert M.A.

    2002-01-01

    Bipolar disorder is frequently encountered in primary care settings, often in the form of poor response to treatment for depression. Although lifetime prevalence of bipolar I disorder is 1%, the prevalence of bipolar spectrum disorders (e.g., bipolar I, bipolar II, and cyclothymia) is much higher, especially among patients with depression. The consequences of misdiagnosis can be devastating. One way to improve recognition of bipolar spectrum disorders is to screen for them. The Mood Disorder ...

  19. Bipolar disorder and age-related functional impairment Prejuízo funcional associado à idade e transtorno bipolar

    Directory of Open Access Journals (Sweden)

    Alice Aita Cacilhas

    2009-12-01

    Full Text Available OBJECTIVE: Although bipolar disorder is a major contributor to functional impairment worldwide, an independent impact of bipolar disorder and ageing on functioning has yet to be demonstrated. The objective of the present study was to evaluate the effect of bipolar disorder on age-related functional status using matched controls as a standard. METHOD: One-hundred patients with bipolar disorder and matched controls were evaluated for disability. Age-related effects controlled for confounders were cross-sectionally evaluated. RESULTS: Patients were significantly more impaired than controls. Regression showed effects for aging in both groups. The effect, size, however, was significantly stronger in patients. CONCLUSION: Bipolar disorder was an important effect modifier of the age impact on functioning. While a longitudinal design is needed to effectively demonstrate this different impact, this study further depicts bipolar disorder as a chronic and progressively impairing illness.OBJETIVO: O transtorno bipolar é responsável por importante parcela do prejuízo funcional ao redor do mundo. Um efeito independente do transtorno bipolar e da idade no funcionamento ainda não foi demonstrado. O presente estudo tem o objetivo de avaliar o efeito do transtorno bipolar no prejuízo funcional relacionado à idade, com controles pareados como padrão. MÉTODO: Cem pacientes com transtorno bipolar e controles pareados foram avaliados para incapacidade. Efeitos relacionados à idade, com controle para confundidores, foram investigados. RESULTADOS: Pacientes tiveram significativamente mais prejuízo que controles. A regressão mostrou efeito para a idade em ambos os grupos, e o efeito foi significativamente mais forte nos pacientes. CONCLUSÃO: O transtorno bipolar foi um importante modificador de efeito no impacto da idade no funcionamento. Enquanto um desenho de estudo longitudinal é necessário para efetivamente demonstrar este impacto diferencial, este

  20. Effect of substitutional doping on temperature dependent electrical parameters of amorphous Se-Te semiconductors

    Science.gov (United States)

    Sharma, Neha; Sharda, Sunanda; Sharma, Dheeraj; Sharma, Vineet; Barman, P. B.; Katyal, S. C.; Sharma, Pankaj; Hazra, S. K.

    2013-09-01

    Steady state current-voltage characteristics of the amorphous (Se80Te20)98Y2 (Y = Ag, Bi, Ge, Cd) semiconductors at different temperatures are reported. The measurements were performed using direct-current voltage bias to understand the basic conductivity mechanism and to evaluate the impact of each substituent on electrical response. The space charge limited conduction mechanism, and the density of states near Fermi level have been calculated. The difference in electrical response due to different substitutions in the glassy matrix is analyzed.

  1. Stability of amorphous silicon alloy triple-junction solar cells and modules

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Aiga, M.; Otsubo, M.

    1987-06-25

    Results on reliability test for amorphous silicon alloy triple-junction solar cells and modules are described. It has been found that, for a-SiGe:H pin cells, reduction of the stress in the film is of first importance for stability. Application of low-temperature-deposited microcrystalline p-layer for each sub cell and of thinner i-layers for the middle and the bottom cells improves stability of triple-junction cells, by enhancing the electric field in the i-layers.

  2. Corrosion resistant amorphous metals and methods of forming corrosion resistant amorphous metals

    Science.gov (United States)

    Farmer, Joseph C.; Wong, Frank M.G.; Haslam, Jeffery J.; Yang, Nancy; Lavernia, Enrique J.; Blue, Craig A.; Graeve, Olivia A.; Bayles, Robert; Perepezko, John H.; Kaufman, Larry; Schoenung, Julie; Ajdelsztajn, Leo

    2014-07-15

    A system for coating a surface comprises providing a source of amorphous metal, providing ceramic particles, and applying the amorphous metal and the ceramic particles to the surface by a spray. The coating comprises a composite material made of amorphous metal that contains one or more of the following elements in the specified range of composition: yttrium (.gtoreq.1 atomic %), chromium (14 to 18 atomic %), molybdenum (.gtoreq.7 atomic %), tungsten (.gtoreq.1 atomic %), boron (.ltoreq.5 atomic %), or carbon (.gtoreq.4 atomic %).

  3. Monolithically integrated Ge CMOS laser

    Science.gov (United States)

    Camacho-Aguilera, Rodolfo

    2014-02-01

    Ge-on-Si devices are explored for photonic integration. Through the development of better growth techniques, monolithic integration, laser design and prototypes, it was possible to probe Ge light emitters with emphasis on lasers. Preliminary worked shows thermal photonic behavior capable of enhancing lamination at high temperatures. Increase luminescence is observed up to 120°C from L-band contribution. Higher temperatures show contribution from Δ -band. The increase carrier thermal contribution suggests high temperature applications for Ge light emitters. A Ge electrically pumped laser was probed under 0.2% biaxial strain and doping concentration ~4.5×1019cm-3 n-type. Ge pnn lasers exhibit a gain >1000cm-1 with 8mW power output, presenting a spectrum range of over 200nm, making Ge the ideal candidate for Si photonics. Large temperatures fluctuations and process limit the present device. Theoretically a gain of >4000cm- gain is possible with a threshold of as low as 1kA/cm2. Improvements in Ge work

  4. Tracer Diffusion Mechanism in Amorphous Solids

    Directory of Open Access Journals (Sweden)

    P. K. Hung

    2011-01-01

    Full Text Available Tracer diffusion in amorphous solid is studied by mean of nB-bubble statistic. The nB-bubble is defined as a group of atoms around a spherical void and large bubble that represents a structural defect which could be eliminated under thermal annealing. It was found that amorphous alloys such as CoxB100−x (x=90, 81.5 and 70 and Fe80P20 suffer from a large number of vacancy bubbles which function like diffusion vehicle. The concentration of vacancy bubble weakly depends on temperature, but essentially on the relaxation degree of considered sample. The diffusion coefficient estimated for proposed mechanism via vacancy bubbles is in a reasonable agreement with experiment for actual amorphous alloys. The relaxation effect for tracer diffusion in amorphous alloys is interpreted by the elimination of vacancy bubbles under thermal annealing.

  5. Theoretical Considerations in Developing Amorphous Solid Dispersions

    DEFF Research Database (Denmark)

    Laitinen, Riikka; Priemel, Petra Alexandra; Surwase, Sachin;

    2014-01-01

    Before pursuing the laborious route of amorphous solid dispersion formulation and development, which is the topic of many of the subsequent chapters in this book, the formulation scientist would benefit from a priori knowledge whether the amorphous route is a viable one for a given drug and how...... to their glass-forming ability and glass stability. In the main parts of this chapter, we review theoretical approaches to determine amorphous drug polymer miscibility and crystalline drug polymer solubility, as a prerequisite to develop amorphous solid dispersions (glass solutions)....... much solubility improvement, and hence increase in bioavailability, can be expected, and what forms of solid dispersion have been developed in the past. In this chapter, we therefore initially define the various forms of solid dispersions, and then go on to discuss properties of pure drugs with respect...

  6. Surface Acidity of Amorphous Aluminum Hydroxide

    Institute of Scientific and Technical Information of China (English)

    K. FUKUSHI; K. TSUKIMURA; H. YAMADA

    2006-01-01

    The surface acidity of synthetic amorphous Al hydroxide was determined by acid/base titration with several complementary methods including solution analyses of the reacted solutions and XRD characterization of the reacted solids. The synthetic specimen was characterized to be the amorphous material showing four broad peaks in XRD pattern. XRD analyses of reacted solids after the titration experiments showed that amorphous Al hydroxide rapidly transformed to crystalline bayerite at the alkaline condition (pH>10). The solution analyses after and during the titration experiments showed that the solubility of amorphous aluminum hydroxide, Ksp =aAl3+/a3H+,was 1010.3,The amount of consumption of added acid or base during the titration experiment was attributed to both the protonation/deprotonation of dissolved Al species and surface hydroxyl group. The surface acidity constants, surface hydroxyl density and specific surface area were estimated by FITEQL 4.0.

  7. [Confusing clinical presentations and differential diagnosis of bipolar disorder].

    Science.gov (United States)

    Gorwood, P

    2004-01-01

    An early recognition of bipolar disorders may have an important impact on the prognosis of this disorder according to different mechanisms. Bipolar disorder is nevertheless not easy to detect, the diagnosis being correctly proposed after, in average more than a couple of Years and three different doctors assessments. A short delay before introducing the relevant treatment should help avoiding inappropriate treatments (prescribing, for example, neuroleptics for long periods, antidepressive drugs each time depressive symptoms occurs, absence of treatment despite mood disorders), with their associated negative impact such as mood-switching, rapid cycling or presence of chronic side-effects stigmates. Furthermore, non-treated mood disorders in bipolar disorder are longer, more stigmatizing and may be associated with an increased risk of suicidal behaviour and mortality. Lastly, compliance, an important factor regarding the long term prognosis of bipolar disorder, should be improved when there is a short delay between correct diagnosis and treatment and onset of the disorder. We therefore propose to review the literature for the different pitfalls involved in the diagnosis of bipolar disorder. Non-bipolar mood-disorders are frequently quoted as one of the alternative diagnosis. Hyperthymic temperament, side-effects of prescribed treatments and organic comorbid disorders may be involved. Bipolar disorders have a sex-ratio closer to 1 (men are thus more frequently of the bipolar type in mood-disorders), with earlier age at onset, and more frequent family history of suicidal attempts and bipolar disorder. Schizo-affective disorders are also a major concern regarding the diagnosis of bipolar disorder. This is explained by flat affects sometimes close to anhedonia, presence of a schizoïd personality in bipolar disorder, persecutive hostility that can be considered to be related to irritability rather than a schizophrenic symptom. Rapid cycling, mixed episodes and short

  8. Ether-like Si-Ge hydrides for applications in synthesis of nanostructured semiconductors and dielectrics.

    Science.gov (United States)

    Tice, Jesse B; Weng, Change; Tolle, John; D'Costa, Vijay R; Singh, Rachna; Menendez, Jose; Kouvetakis, John; Chizmeshya, Andrew V G

    2009-09-14

    Hydrolysis reactions of silyl-germyl triflates are used to produce ether-like Si-Ge hydride compounds including H(3)SiOSiH(3) and the previously unknown O(SiH(2)GeH(3))(2). The structural, energetic and vibrational properties of the latter were investigated by experimental and quantum chemical simulation methods. A combined Raman, infrared and theoretical analysis indicated that the compound consists of an equal mixture of linear and gauche isomers in analogy to the butane-like H(3)GeSiH(2)SiH(2)GeH(3) with an exceedingly small torsional barrier of approximately 0.2 kcal mol(-1). This is also corroborated by thermochemistry simulations which indicate that the energy difference between the isomers is less than 1 kcal mol(-1). Proof-of-principle depositions of O(SiH(2)GeH(3))(2) at 500 degrees C on Si(100) yielded nearly stoichiometric Si(2)Ge(2)O materials, closely reflecting the composition of the molecular core. A complete characterization of the film by RBS, XTEM, Raman and IR ellipsometry revealed the presence of Si(0.30)Ge(0.70) quantum dots embedded within an amorphous matrix of Si-Ge-O suboxide, as required for the fabrication of high performance nonvolatile memory devices. The use of readily available starting materials coupled with facile purification and high yields also makes the above molecular approach an attractive synthesis route to H(3)SiOSiH(3) with industrial applications in the formation of Si-O-N high-k gate materials in high-mobility SiGe based transistors.

  9. Technology computer aided design for Si, SiGe and GaAs integrated circuits

    CERN Document Server

    Armstrong, GA

    2007-01-01

    The first book to deal with a broad spectrum of process and device design, and modelling issues related to semiconductor devices, bridging the gap between device modelling and process design using TCAD. Examples for types of Si-, SiGe-, GaAs- and InP-based heterostructure MOS and bipolar transistors are compared with experimental data from state-of-the-art devices. With various aspects of silicon heterostructures, this book presents a comprehensive perspective of emerging fields and covers topics ranging from materials to fabrication, devices, modelling and applications. Aimed at research-and-

  10. Device Physics Analysis of Parasitic Conduction Band Barrier Formation in SiGe HBTs

    Science.gov (United States)

    Roenker, K. P.; Alterovitz, S. A.

    2000-01-01

    This paper presents a physics-based model describing the current-induced formation of a parasitic barrier in the conduction band at the base collector heterojunction in npn SiGe heterojunction bipolar transistors (HBTs). Due to the valence band discontinuity DELTA E(sub v), hole injection into the collector at the onset of base pushout is impeded, which gives rise to formation of a barrier to electron transport which degrades the device's high frequency performance. In this paper, we present results from an analytical model for the height of the barrier calculated from the device's structure as a function of the collector junction bias and collector current density.

  11. A Magnetic Sensor with Amorphous Wire

    Directory of Open Access Journals (Sweden)

    Dongfeng He

    2014-06-01

    Full Text Available Using a FeCoSiB amorphous wire and a coil wrapped around it, we have developed a sensitive magnetic sensor. When a 5 mm long amorphous wire with the diameter of 0.1 mm was used, the magnetic field noise spectrum of the sensor was about 30 pT/ÖHz above 30 Hz. To show the sensitivity and the spatial resolution, the magnetic field of a thousand Japanese yen was scanned with the magnetic sensor.

  12. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  13. A Magnetic Sensor with Amorphous Wire

    OpenAIRE

    Dongfeng He; Mitsuharu Shiwa

    2014-01-01

    Using a FeCoSiB amorphous wire and a coil wrapped around it, we have developed a sensitive magnetic sensor. When a 5 mm long amorphous wire with the diameter of 0.1 mm was used, the magnetic field noise spectrum of the sensor was about 30 pT/ÖHz above 30 Hz. To show the sensitivity and the spatial resolution, the magnetic field of a thousand Japanese yen was scanned with the magnetic sensor.

  14. Emerging trends in the stabilization of amorphous drugs

    DEFF Research Database (Denmark)

    Laitinen, Riikka; Löbmann, Korbinian; Strachan, Clare J.;

    2013-01-01

    water-soluble drugs can be increased by the formation of stabilized amorphous forms. Currently, formulation as solid polymer dispersions is the preferred method to enhance drug dissolution and to stabilize the amorphous form of a drug. The purpose of this review is to highlight emerging alternative...... methods to amorphous polymer dispersions for stabilizing the amorphous form of drugs. First, an overview of the properties and stabilization mechanisms of amorphous forms is provided. Subsequently, formulation approaches such as the preparation of co-amorphous small-molecule mixtures and the use...... of mesoporous silicon and silica-based carriers are presented as potential means to increase the stability of amorphous pharmaceuticals....

  15. Photo-induced potential barrier in As-Se-Ge films

    Science.gov (United States)

    Katyal, S. C.; Okano, S.; Suzuki, M.; Bando, T.

    1988-05-01

    Photo-excited effects in AsSeGe and AsSeGeSn amorphous films have been studied under illumination of different light sources. AsSeGe system exhibited rectifying characteristics under illumination of the light with hν > E g, while AsSeGeSn film did not show such phenomena. The illumination of the IR light along with the light of hν > E g weakened the rectification behavior. The photovoltage and I-V characteristics results suggest the existence of "photo-induced" potential barrier in AsSeGe system, which is considered to concern the creation and destruction of neutral defect states D°.

  16. IBA study of SiGe/SiO{sub 2} nanostructured multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Barradas, Nuno P., E-mail: nunoni@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 (ao km 139,7), 2695-066 Bobadela LRS (Portugal); Laboratório de Engenharia Nuclear, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 (ao km 139,7), 2695-066 Bobadela LRS (Portugal); Alves, E. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Vieira, E.M.F. [Centre of Physics and Physics Department, University of Minho, 4710-057 Braga (Portugal); Parisini, A. [CNR-IMM Sezione di Bologna, via P. Gobetti 101, 40129 Bologna (Italy); Conde, O. [Physics Department and ICEMS, University of Lisbon, 1749-016 Lisboa (Portugal); Martín-Sánchez, J. [Laser Processing Group, Instituto de Óptica, CSIC, C/Serrano 121, 28006 Madrid (Spain); Rolo, A.G. [Centre of Physics and Physics Department, University of Minho, 4710-057 Braga (Portugal); Chahboun, A. [Centre of Physics and Physics Department, University of Minho, 4710-057 Braga (Portugal); FST Tanger, Physics Department, BP 416 Tanger (Morocco); Gomes, M.J.M. [Centre of Physics and Physics Department, University of Minho, 4710-057 Braga (Portugal)

    2014-07-15

    SiGe/SiO{sub 2} multilayers with layer thickness of 5 nm were deposited with RF magnetron sputtering. The as deposited samples had well defined SiGe amorphous layers. Different annealing treatments were made to promote the formation of SiGe nanocrystals. We report an ion beam analysis study with the Rutherford backscattering and elastic recoil analysis detection techniques, in order to determine the thickness and composition of the nanolayers, and gain insight into the evolution of the roughness of the layers. The results are correlated with other structural properties of the samples, as measured with complementary techniques such as grazing incidence X-ray diffraction annular dark field scanning transmission electron microscopy and high resolution transmission electron microscopy.

  17. High efficiency a-Si:H/a-SiGe:H tandem solar cells fabricated with the combination of V- and U-shaped band gap profiling techniques

    Science.gov (United States)

    Inthisang, Sorapong; Krajangsang, Taweewat; Hongsingthong, Aswin; Limmanee, Amornrat; Kittisontirak, Songkiate; Jaroensathainchok, Suttinan; Moolakorn, Apichan; Dousse, Adrien; Sritharathikhun, Jaran; Sriprapha, Kobsak

    2015-08-01

    Hydrogenated amorphous silicon germanium (a-SiGe:H) films prepared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) using a mixture of SiH4, H2, and GeH4 were investigated for their use as the bottom cell of amorphous silicon/amorphous silicon germanium (a-Si:H/a-SiGe:H) tandem solar cell structures. Narrow optical band gaps (Eopt) in the range of 1.5 to 1.6 eV were obtained by varying the GeH4/(SiH4 + GeH4) gas flow rate ratio in low-temperature deposition. The a-SiGe:H films deposited with various GeH4/(SiH4 + GeH4) gas flow rate ratios were used as intrinsic layers for the a-Si:H/a-SiGe:H tandem solar cells with different graded band gaps: V-, VU-, and U-shapes. It was found that using the VU-shape improves the solar cell efficiency owing to a higher Jsc when compared with using V-shape. The VU-shape’s Voc and FF are also improved when compared with the U-shape’s Voc and FF. As a result, a high efficiency of 11.0% (Voc = 1.74 V, Jsc = 9.07 mA/cm2, and FF = 0.70) was successfully achieved with the solar cells fabricated using the VU-shape graded band gap technique.

  18. Effects of Sn Substitution on Thermoelectric Properties of Ge4SbTe5

    Science.gov (United States)

    Williams, Jared B.; Mather, Spencer; Morelli, Donald T.

    2016-02-01

    Phase-change materials are identified by their ability to rapidly alternate between amorphous and crystalline phases upon heating, exhibiting large contrast in the optical/electrical properties of the respective phases. Such materials are primarily used in memory storage applications, but recently they have also been identified as potential thermoelectric materials. Many of the phase-change materials studied today can be found on the pseudobinary (GeTe)1- x (Sb2Te3) x tie-line. Ge4SbTe5, a single-phase compound just off of the (GeTe)1- x (Sb2Te3) x tie-line, forms in a metastable rocksalt crystal structure at room temperature. It has been found that stoichiometric and undoped Ge4SbTe5 exhibits thermal conductivity of ~1.2 W/m-K at high temperature and a dramatic decrease in electrical resistivity at 623 K due to a structural phase transition, which leads to a large enhancement in both thermoelectric power factor and thermoelectric figure of merit at 823 K. Introducing point defects via isoelectronic substitutions can be an effective means of reducing thermal conductivity and enhancing thermoelectric performance. We present a study of the effects of Sn substitution for Ge on the electrical and thermal transport properties of Ge4SbTe5.

  19. Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Guchhait, S.; Jamil, M.; Ohldag, H.; Mehta, A.; Arenholz, E.; Lian, G.; Li Fatou, A.; Ferrer, D. A.; Markert, J. T.; Colombo, L.; Banerjee, S. K.

    2011-01-05

    We have studied ferromagnetism of Mn-implanted epitaxial Ge films on silicon. The Ge films were grown by ultrahigh vacuum chemical vapor deposition using a mixture of germane (GeH{sub 4}) and methylgermane (CH{sub 3}GeH{sub 3}) gases with a carbon concentration of less than 1 at. %, and observed surface rms roughness of 0.5 nm, as measured by atomic force microscopy. Manganese ions were implanted in epitaxial Ge films grown on Si (100) wafers to an effective concentration of 16, 12, 6, and 2 at. %. Superconducting quantum interference device measurements showed that only the three highest Mn concentration samples are ferromagnetic, while the fourth sample, with [Mn] = 2 at. %, is paramagnetic. X-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements indicate that localized Mn moments are ferromagnetically coupled below the Curie temperature. Isothermal annealing of Mn-implanted Ge films with [Mn] = 16 at. % at 300 C for up to 1200 s decreases the magnetization but does not change the Curie temperature, suggesting that the amount of the magnetic phase slowly decreases with time at this anneal temperature. Furthermore, transmission electron microscopy and synchrotron grazing incidence x-ray diffraction experiments show that the Mn-implanted region is amorphous, and we believe that it is this phase that is responsible for the ferromagnetism. This is supported by our observation that high-temperature annealing leads to recrystallization and transformation of the material into a paramagnetic phase.

  20. The bipolar puzzle, adding new pieces. Factors associated with bipolar disorder, Genetic and environmental influences

    NARCIS (Netherlands)

    van der Schot, A.C.

    2009-01-01

    The focus of this thesis is twofold. The first part will discuss the structural brain abnormalities and schoolperformance associated with bipolar disorder and the influence of genetic and/or environmental factors to this association. It is part of a large twin study investigating several potential b

  1. <300> GeV team

    CERN Multimedia

    1971-01-01

    The 300 GeV team had been assembled. In the photograph are Hans Horisberger, Clemens Zettler, Roy Billinge, Norman Blackburne, John Adams, Hans-Otto Wuster, Lars Persson, Bas de Raad, Hans Goebel, Simon Van der Meer.

  2. In含量对Ge-In-Se薄膜光学特性的影响%Effect of In Content on Optical Properties of Ge-In-Se Thin Films

    Institute of Scientific and Technical Information of China (English)

    陈芬; 王永辉; 聂秋华; 王国祥; 陈昱; 沈祥; 戴世勋

    2013-01-01

    Amorphous Ge-In-Se thin films were prepared by a magnetron co-sputtering technique.The morphology,structure and optical properties of the thin films were analyzed by X-ray diffraction,visible/near-infrared transmission spectroscopy and Raman spectroscopy,respectively.The results show that the Ge-In-Se thin films have the amorphous characteristics.It was indicated that the high frequency vibration mode of Ge-Se bond in [GeSe4] tetrahedral was the main one in the Ge-In-Se thin films,and the vibration intensity decreased with increasing In content.When In content was 13.87% in mole,the [GeSe4] tetrahedral disappears and [InSe4]tetrahedral became the dominate structure.According to the analysis by the Swanepoel method and the classic Tauc equation,it was found that the red shift appeared at a short-wavelength absorption edge,the refractive index increased and the optical band gap decreased with the increase of In content.%采用磁控溅射法制备了Ge-In-Se硫系薄膜,利用X射线衍射、可见-近红外吸收光谱和Raman光谱分析等技术对Ge-In-Se硫系薄膜的相态、结构和光学特性进行了研究和分析.结果表明:该Ge-In-Se薄膜具有良好的非晶特性.Raman光谱分析表明:[GeSe4]四面体Ge-Se键的高频振动模式是该薄膜的主要振动模式之一,且Ge-Se键的振动强度随着m含量的增加而减小;当In的含量达到13.87%(摩尔分数)时,[GeSe4]四面体消失,而[InSE4]四面体的对称伸缩振动模式成为了主要振动模式.采用Swanepoel方法和经典Tauc方程计算发现:随着In含量增加,该薄膜的短波吸收限红移,折射率逐渐增大,光学带隙逐渐减小.

  3. Psychodynamics of hypersexuality in children and adolescents with bipolar disorder.

    Science.gov (United States)

    Adelson, Stewart

    2010-01-01

    It has recently become evident that bipolar disorder exists in children and adolescents. The criteria for making the diagnosis of juvenile bipolar disorder (JBD) are in the process of being proposed for the fifth edition of the Diagnostic and Statistical Manual (DSM-V). In adults, a criterion for bipolar disorder is excessive involvement in pleasurable activities including hypersexuality. Recently, some clinicians and researchers have suggested that hypersexuality be included as a criterion for JBD as well. Although abnormal sexuality has been reported to be present in some youth thought to have JBD, the reason for this association is not yet clear. Hypersexuality may be primary and intrinsic to bipolar disorder in youth, secondary and associated with it as the result of psychosocial influences or psychodynamic factors, or due to general aggression and disruptive behavior. Not only have developmental psychosocial factors that may influence sexuality in children and adolescence not been fully investigated, but psychodynamic influences have been omitted from modern etiological constructs as well. This report discusses the importance of psychosocial and psychodynamic influences on the sexual experience and activity of bipolar children. It is proposed that a developmental, psychodynamically informed model is helpful in understanding sexuality in children and adolescents with bipolar disorder. It is also suggested that assessment of psychosocial and psychodynamic influences on the sexuality of bipolar children is necessary in order to adequately assess whether hypersexuality should be a criterion of bipolar disorder in youth.

  4. Polygenic risk scores for schizophrenia and bipolar disorder predict creativity

    NARCIS (Netherlands)

    Power, R.A.; Steinberg, S.; Bjornsdottir, G.; Rietveld, C.A.; Abdellaoui, A.; Nivard, M.M.; Johannesson, M.; Galesloot, T.E.; Hottenga, J.J.; Willemsen, G.; Cesarini, D.; Benjamin, D.J.; Magnusson, P.K.; Ullen, F.; Tiemeier, H.; Hofman, A.; Rooij, F.J. van; Walters, G.B.; Sigurdsson, E.; Thorgeirsson, T.E.; Ingason, A.; Helgason, A.; Kong, A.; Kiemeney, B.; Koellinger, P.; Boomsma, D.I.; Gudbjartsson, D.; Stefansson, H.; Stefansson, K.

    2015-01-01

    We tested whether polygenic risk scores for schizophrenia and bipolar disorder would predict creativity. Higher scores were associated with artistic society membership or creative profession in both Icelandic (P = 5.2 x 10(-6) and 3.8 x 10(-6) for schizophrenia and bipolar disorder scores, respectiv

  5. Bipolar Disorder in Children: Implications for Speech-Language Pathologists

    Science.gov (United States)

    Quattlebaum, Patricia D.; Grier, Betsy C.; Klubnik, Cynthia

    2012-01-01

    In the United States, bipolar disorder is an increasingly common diagnosis in children, and these children can present with severe behavior problems and emotionality. Many studies have documented the frequent coexistence of behavior disorders and speech-language disorders. Like other children with behavior disorders, children with bipolar disorder…

  6. The Enigma of Bipolar Disorder in Children and Adolescents

    Science.gov (United States)

    Hatchett, Gregory T.

    2009-01-01

    In the past decade, there has been a proliferation in the number of children and adolescents diagnosed with bipolar disorder. Except in rare cases, the young people who receive this diagnosis do not meet the strict diagnostic criteria for bipolar disorder I or II in the DSM-IV-TR. Many pediatric psychiatrists insist there are important development…

  7. Olfactocentric Paralimbic Cortex Morphology in Adolescents with Bipolar Disorder

    Science.gov (United States)

    Wang, Fei; Kalmar, Jessica H.; Womer, Fay Y.; Edmiston, Erin E.; Chepenik, Lara G.; Chen, Rachel; Spencer, Linda; Blumberg, Hilary P.

    2011-01-01

    The olfactocentric paralimbic cortex plays a critical role in the regulation of emotional and neurovegetative functions that are disrupted in core features of bipolar disorder. Adolescence is thought to be a critical period in both the maturation of the olfactocentric paralimbic cortex and in the emergence of bipolar disorder pathology. Together,…

  8. Pediatric Bipolar Disorder: Evidence for Prodromal States and Early Markers

    Science.gov (United States)

    Luby, Joan L.; Navsaria, Neha

    2010-01-01

    Background: Childhood bipolar disorder remains a controversial but increasingly diagnosed disorder that is associated with significant impairment, chronic course and treatment resistance. Therefore, the search for prodromes or early markers of risk for later childhood bipolar disorder may be of great importance for prevention and/or early…

  9. A Scalable Mextram Model for Advanced Bipolar Circuit Design

    NARCIS (Netherlands)

    Wu, H.-C.

    2007-01-01

    In this thesis, a referenced based scaling approach and its parameter extraction for the bipolar transistor model Mextram is proposed. It is mainly based on the physical properties of the Mextram parameters, which scale with the junction temperature and geometry of the bipolar transistor. The scalab

  10. SEMICLASSICAL LIMIT FOR BIPOLAR QUANTUM DRIFT-DIFFUSION MODEL

    Institute of Scientific and Technical Information of China (English)

    Ju Qiangchang; Chen Li

    2009-01-01

    Semiclassical limit to the solution of transient bipolar quantum drift-diffusion model in semiconductor simulation is discussed. It is proved that the semiclassical limit ofthis solution satisfies the classical bipolar drift-diffusion model. In addition, the authors also prove the existence of weak solution.

  11. New types of bipolar fuzzy sets in -semihypergroups

    Directory of Open Access Journals (Sweden)

    Naveed Yaqoob

    2016-04-01

    Full Text Available The notion of bipolar fuzzy set was initiated by Lee (2000 as a generalization of the notion fuzzy sets and intuitionistic fuzzy sets, which have drawn attention of many mathematicians and computer scientists. In this paper, we initiate a study on bipolar ( , -fuzzy sets in -semihypergroups. By using the concept of bipolar ( , -fuzzy sets (Yaqoob and Ansari, 2013, we introduce the notion of bipolar ( , -fuzzy sub -semihypergroups (-hyperideals and bi--hyperideals and discuss some basic results on bipolar ( , -fuzzy sets in -semihypergroups. Furthermore, we define the bipolar fuzzy subset ,               and prove that if  ,       is a bipolar ( , -fuzzy sub -semihypergroup (resp., -hyperideal and bi--hyperideal of H; then ,               is also a bipolar ( , -fuzzy sub -semihypergroup (resp., -hyperideal and bi--hyperideal of H.

  12. Asymmetric bipolar membranes in acid-base electrodialysis

    NARCIS (Netherlands)

    Wilhelm, Friedrich G.; Punt, Ineke; Vegt, van der Nico F.A.; Strathmann, H.; Wessling, M.

    2002-01-01

    In this experimental study, the influence of asymmetric bipolar membranes on the salt impurities in the acid and base product is investigated. The thickness of one, the other, or both ion-permeable layers of a bipolar membrane is increased. With increased layer thickness, the current-voltage curves

  13. The CBCL Bipolar Profile and Attention, Mood, and Behavior Dysregulation

    Science.gov (United States)

    Doerfler, Leonard A.; Connor, Daniel F.; Toscano, Peter F.

    2011-01-01

    Biederman and colleagues reported that a CBCL profile identified youngsters who were diagnosed with bipolar disorder. Some studies found that this CBCL profile does not reliably identify children who present with bipolar disorder, but nonetheless this CBCL does identify youngsters with severe dysfunction. However, the nature of the impairment of…

  14. Tiagabine in treatment refractory bipolar disorder : a clinical case series

    NARCIS (Netherlands)

    Suppes, T; Chisholm, KA; Dhavale, D; Frye, MA; Atshuler, LL; McElroy, SL; Keck, PE; Nolen, WA; Kupka, R; Denicoff, KD; Leverich, GS; Rush, AJ; Post, RM

    2002-01-01

    Objectives: Anticonvulsants have provided major treatment advances for patients with bipolar disorder. Many of these drugs, including several with proven efficacy in bipolar mania or depression, enhance the activity of the gamma-amino butyric acid (GABA) neurotransmitter system. A new anticonvulsant

  15. NEW FAMILY OF BIPOLAR SEQUENCES AND ITS CORRELATION SPECTRUM

    Institute of Scientific and Technical Information of China (English)

    Hu Fei; Wen Hong; Jin Fan

    2004-01-01

    Based on a class of bipolar sequences with two-values autocorrelation functions, a new family of bipolar sequences is constructed and its correlation spectrum is calculated. It is shown that the new family is optimal with respect to Welch's bound and is different from the small set of Kasami sequences, while both of them have the same correlation properties.

  16. [Self-assessment questionnaires for the investigation of bipolarity].

    Science.gov (United States)

    Tsopelas, Ch; Konstantinidou, D; Douzenis, A

    2010-01-01

    Contemporary research shows that bipolar disorders are very often faced initially as depression, while the precise diagnosis usually delay 8-10 years or more. As a result of this delay in the diagnosis, the patients do not receive appropriate treatment and are not led to recession of their symptoms. Roughly one third of depressed patients are treated at mental health services and two thirds at the primary care health services. Regarding the psychiatric patients that are treated in the secondary and trietary services of mental health, various researches indicate that the bipolar disorders and especially Bipolar Disorder II are under-diagnosed and consequently they do not receive satisfactory treatment with important repercussions in the professional and social existence of Bipolar Disorders' patients. The imperative need for early diagnosis and treatment in patients with bipolar disorders is obvious, in order to decrease the big time of delay in the diagnosis of Bipolar disorders. Patient self-completed questionnaires, which are small in duration and well structured, can contribute in the early recognition of disorders of bipolar spectrum in patients that are treated at the outpatient clinics. In this bibliographic research we compare two questionnaires (the MDQ and the HCL-32) with regard to their psychometrics faculties and the possibility of use in the early diagnosis and treatment of individuals that suffers from disorders of Bipolar spectrum.

  17. People-Things and Data-Ideas: Bipolar Dimensions?

    Science.gov (United States)

    Tay, Louis; Su, Rong; Rounds, James

    2011-01-01

    We examined a longstanding assumption in vocational psychology that people-things and data-ideas are bipolar dimensions. Two minimal criteria for bipolarity were proposed and examined across 3 studies: (a) The correlation between opposite interest types should be negative; (b) after correcting for systematic responding, the correlation should be…

  18. Mechanisms of Centrosome Separation and Bipolar Spindle Assembly

    NARCIS (Netherlands)

    Tanenbaum, Marvin E.; Medema, Rene H.

    2010-01-01

    Accurate segregation of chromosomes during cell division is accomplished through the assembly of a bipolar microtubule-based structure called the mitotic spindle. Work over the past two decades has identified a core regulator of spindle bipolarity, the microtubule motor protein kinesin-5. However, a

  19. Premorbid intelligence and educational level in bipolar and unipolar disorders

    DEFF Research Database (Denmark)

    Sørensen, Holger Jelling; Sæbye, Ditte; Urfer-Parnas, Annick

    2012-01-01

    Registry-based studies have found no or weak associations between premorbid intelligence and the broad entity of affective spectrum disorder, but none of the studies compared bipolar/unipolar subgroups.......Registry-based studies have found no or weak associations between premorbid intelligence and the broad entity of affective spectrum disorder, but none of the studies compared bipolar/unipolar subgroups....

  20. Risk Factors of Attempted Suicide in Bipolar Disorder

    Science.gov (United States)

    Cassidy, Frederick

    2011-01-01

    Suicide rates of bipolar patients are among the highest of any psychiatric disorder, and improved identification of risk factors for attempted and completed suicide translates into improved clinical outcome. Factors that may be predictive of suicidality in an exclusively bipolar population are examined. White race, family suicide history, and…

  1. Strain relaxation during solid-phase epitaxial crystallisation of Ge{sub x}Si{sub 1-x} alloy layers with depth dependent G{sub e} compositions

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Wahchung; Elliman, R.G.; Kringhoj, P. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

    1993-12-31

    The solid-phase epitaxial crystallisation of depth dependent Ge{sub x}Si{sub lx} alloy layers produced by implanting Ge into Si substrates was studied. In-situ monitoring was done using time-resolved reflectivity (TRR) whilst post-anneal defect structures were characterised by Rutherford backscattering and channeling spectrometry (RBS-C) and transmission electron microscopy (TEM). Particular attention was directed at Ge concentrations above the critical concentration for the growth of fully strained layers. Strain relief is shown to be correlated with a sudden reduction in crystallisation velocity caused by roughening of the crystalline/amorphous interface. 11 refs., 1 tab., 2 figs.

  2. N-doped GeTe phase change material for high-temperature data retention and low-power consumption

    Science.gov (United States)

    Zhang, Jianhao; Hu, Yifeng; Zhu, Xiaoqin; Zou, Hua; Yuan, Li; Xue, Jianzhong; Sui, Yongxing; Wu, Weihua; Song, Sannian; Song, Zhitang

    2016-10-01

    The amorphous-to-crystalline transitions of N-doped GeTe films are investigated by in situ film resistance measurements. Both the crystallization temperature and resistance of the N-doped films increase. The analysis of X-ray diffraction (XRD) measurement indicates that the grain size of the films with more nitrogen content can be refined, leading to the improvement in the resistance and thermal stability of the phase change films. The N-doped GeTe films have higher activation energy for crystallization. The 10-year lifetime is raised from 90°C of undoped GeTe film to 138°C of the N-doped GeTe film. The better surface roughness is confirmed by atomic force microscopy. The phase change speed is evaluated by the picosecond laser pump-probe technology.

  3. Three-dimensional fabrication and characterisation of core-shell nano-columns using electron beam patterning of Ge-doped SiO2

    DEFF Research Database (Denmark)

    Gontard, Lionel C.; Jinschek, Joerg R.; Ou, Haiyan;

    2012-01-01

    A focused electron beam in a scanning transmission electron microscope (STEM) is used to create arrays of core-shell structures in a specimen of amorphous SiO2 doped with Ge. The same electron microscope is then used to measure the changes that occurred in the specimen in three dimensions using e...

  4. Secondary growth mechanism of SiGe islands deposited on a mixed-phase microcrystalline Si by ion beam co-sputtering.

    Science.gov (United States)

    Ke, S Y; Yang, J; Qiu, F; Wang, Z Q; Wang, C; Yang, Y

    2015-11-01

    We discuss the SiGe island co-sputtering deposition on a microcrystalline silicon (μc-Si) buffer layer and the secondary island growth based on this pre-SiGe island layer. The growth phenomenon of SiGe islands on crystalline silicon (c-Si) is also investigated for comparison. The pre-SiGe layer grown on μc-Si exhibits a mixed-phase structure, including SiGe islands and amorphous SiGe (a-SiGe) alloy, while the layer deposited on c-Si shows a single-phase island structure. The preferential growth and Ostwald ripening growth are shown to be the secondary growth mechanism of SiGe islands on μc-Si and c-Si, respectively. This difference may result from the effect of amorphous phase Si (AP-Si) in μc-Si on the island growth. In addition, the Si-Ge intermixing behavior of the secondary-grown islands on μc-Si is interpreted by constructing the model of lateral atomic migration, while this behavior on c-Si is ascribed to traditional uphill atomic diffusion. It is found that the aspect ratios of the preferential-grown super islands are higher than those of the Ostwald-ripening ones. The lower lateral growth rate of super islands due to the lower surface energy of AP-Si on the μc-Si buffer layer for the non-wetting of Ge at 700 °C and the stronger Si-Ge intermixing effect at 730 °C may be responsible for this aspect ratio difference.

  5. Enhancing outcomes in patients with bipolar disorder: results from the Bipolar Disorder Center for Pennsylvanians Study

    Science.gov (United States)

    Fagiolini, Andrea; Frank, Ellen; Axelson, David A; Birmaher, Boris; Cheng, Yu; Curet, David E; Friedman, Edward S; Gildengers, Ariel G; Goldstein, Tina; Grochocinski, Victoria J; Houck, Patricia R; Stofko, Mary G; Thase, Michael E; Thompson, Wesley K; Turkin, Scott R; Kupfer, David J

    2012-01-01

    Introduction We developed models of Specialized Care for Bipolar Disorder (SCBD) and a psychosocial treatment [Enhanced Clinical Intervention (ECI)] that is delivered in combination with SCBD. We investigated whether SCBD and ECI + SCBD are able to improve outcomes and reduce health disparities for young and elderly individuals, African Americans, and rural residents with bipolar disorder. Method Subjects were 463 individuals with bipolar disorder, type I, II, or not otherwise specified, or schizoaffective disorder, bipolar type, randomly assigned to SCBD or ECI + SCBD and followed longitudinally for a period of one to three years at four clinical sites. Results Both treatment groups significantly improved over time, with no significant differences based on age, race, or place of residence, except for significantly greater improvement among elderly versus adult subjects. Improvement in quality of life was greater in the ECI + SCBD group. Of the 299 participants who were symptomatic at study entry, 213 achieved recovery within 24 months, during which 86 of the 213 subjects developed a new episode. No significant difference was found for race, place of residence, or age between the participants who experienced a recurrence and those who did not. However, the adolescent patients were less likely than the adult and elderly patients to experience a recurrence. Conclusion This study demonstrated the effectiveness of SCBD and the additional benefit of ECI independent of age, race, or place of residence. It also demonstrated that new mood episodes are frequent in individuals with bipolar disorder who achieve recovery and are likely to occur in spite of specialized, guideline-based treatments. PMID:19500091

  6. Analysis of bipolar and CMOS amplifiers

    CERN Document Server

    Sodagar, Amir M

    2007-01-01

    The classical approach to analog circuit analysis is a daunting prospect to many students, requiring tedious enumeration of contributing factors and lengthy calculations. Most textbooks apply this cumbersome approach to small-signal amplifiers, which becomes even more difficult as the number of components increases. Analysis of Bipolar and CMOS Amplifiers offers students an alternative that enables quick and intuitive analysis and design: the analysis-by-inspection method.This practical and student-friendly text demonstrates how to achieve approximate results that fall within an acceptable ran

  7. A new bipolar Qtrim power supply system

    Energy Technology Data Exchange (ETDEWEB)

    Mi, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Bruno, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Drozd, J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Nolan, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Orsatti, F. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Heppener, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Di Lieto, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Schultheiss, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Samms, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Zapasek, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Sandberg, J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-05-03

    This year marks the 15th run of RHIC (Relativistic Heavy Ion Collider) operations. The reliability of superconducting magnet power supplies is one of the essential factors in the entire accelerator complex. Besides maintaining existing power supplies and their associated equipment, newly designed systems are also required based on the physicist’s latest requirements. A bipolar power supply was required for this year’s main quadruple trim power supply. This paper will explain the design, prototype, testing, installation and operation of this recently installed power supply system.

  8. Animal models of recurrent or bipolar depression.

    Science.gov (United States)

    Kato, T; Kasahara, T; Kubota-Sakashita, M; Kato, T M; Nakajima, K

    2016-05-03

    Animal models of mental disorders should ideally have construct, face, and predictive validity, but current animal models do not always satisfy these validity criteria. Additionally, animal models of depression rely mainly on stress-induced behavioral changes. These stress-induced models have limited validity, because stress is not a risk factor specific to depression, and the models do not recapitulate the recurrent and spontaneous nature of depressive episodes. Although animal models exhibiting recurrent depressive episodes or bipolar depression have not yet been established, several researchers are trying to generate such animals by modeling clinical risk factors as well as by manipulating a specific neural circuit using emerging techniques.

  9. State-related alterations of gene expression in bipolar disorder

    DEFF Research Database (Denmark)

    Munkholm, Klaus; Vinberg, Maj; Berk, Michael

    2012-01-01

    Munkholm K, Vinberg M, Berk M, Kessing LV. State-related alterations of gene expression in bipolar disorder: a systematic review. Bipolar Disord 2012: 14: 684-696. © 2012 The Authors. Journal compilation © 2012 John Wiley & Sons A/S. Objective:  Alterations in gene expression in bipolar disorder...... vulnerability pathways. This review therefore evaluated the evidence for whether gene expression in bipolar disorder is state or trait related. Methods:  A systematic review, using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline for reporting systematic reviews, based...... on comprehensive database searches for studies on gene expression in patients with bipolar disorder in specific mood states, was conducted. We searched Medline, Embase, PsycINFO, and The Cochrane Library, supplemented by manually searching reference lists from retrieved publications. Results:  A total of 17...

  10. Activation of suicidal ideation with adjunctive rufinamide in bipolar disorder.

    Science.gov (United States)

    Kaufman, Kenneth R; Struck, Peter J

    2011-02-01

    Antiepileptic drugs are effective psychotropics, especially for bipolar disorder, which leads to their use off-label in treatment-refractory cases. A recent publication suggests that rufinamide may be beneficial adjunctively for bipolar disorder with comorbid psychopathology. This report addresses two negative cases with significant psychiatric adverse effects: increased depression, agitation, and activation of suicidal ideation. These findings suggest that adjunctive rufinamide may lead to increased suicidal ideation in patients with treatment-refractory bipolar disorder. Secondary to the course of severe bipolar disorder, rufinamide cannot be specifically implicated; however, clinicians should be aware of this potential significant adverse effect and monitor high-risk patients. Further studies are required to address rufinamide treatment efficacy and severity of adverse effects in patients with bipolar disorder.

  11. The role of estrogen in bipolar disorder, a review

    DEFF Research Database (Denmark)

    Meinhard, Ninja; Kessing, Lars Vedel; Vinberg, Maj

    2014-01-01

    BACKGROUND: It appears that the female reproductive events and hormonal treatments may impact the course of bipolar disorder in women. In particular, childbirth is known to be associated with onset of affective episodes in women with bipolar disorder. During the female reproductive events the sex...... hormones, e.g. estrogen, are fluctuating and particularly postpartum there is a steep fall in the levels of serum estrogen. The role of estrogen in women with bipolar disorder is, however, not fully understood. AIM: The main objective of this review is to evaluate the possible relation between serum...... estrogen levels and women with bipolar disorder including studies of the anti manic effects of the selective estrogen receptor modulator tamoxifen. METHOD: A systematically literature search on PubMed was conducted: two studies regarding the connection between serum estrogen levels and women with bipolar...

  12. Electrons and phonons in amorphous semiconductors

    Science.gov (United States)

    Prasai, Kiran; Biswas, Parthapratim; Drabold, D. A.

    2016-07-01

    The coupling between lattice vibrations and electrons is one of the central concepts of condensed matter physics. The subject has been deeply studied for crystalline materials, but far less so for amorphous and glassy materials, which are among the most important for applications. In this paper, we explore the electron-lattice coupling using current tools of a first-principles computer simulation. We choose three materials to illustrate the phenomena: amorphous silicon (a-Si), amorphous selenium (a-Se) and amorphous gallium nitride (a-GaN). In each case, we show that there is a strong correlation between the localization of electron states and the magnitude of thermally induced fluctuations in energy eigenvalues obtained from the density-functional theory (i.e. Kohn-Sham eigenvalues). We provide a heuristic theory to explain these observations. The case of a-GaN, a topologically disordered partly ionic insulator, is distinctive compared to the covalent amorphous examples. Next, we explore the consequences of changing the charge state of a system as a proxy for tracking photo-induced structural changes in the materials. Where transport is concerned, we lend insight into the Meyer-Neldel compensation rule and discuss a thermally averaged Kubo-Greenwood formula as a means to estimate electrical conductivity and especially its temperature dependence. We close by showing how the optical gap of an amorphous semiconductor can be computationally engineered with the judicious use of Hellmann-Feynman forces (associated with a few defect states) using molecular dynamics simulations. These forces can be used to close or open an optical gap, and identify a structure with a prescribed gap. We use the approach with plane-wave density functional methods to identify a low-energy amorphous phase of silicon including several coordination defects, yet with a gap close to that of good quality a-Si models.

  13. Minor physical anomalies in bipolar I and bipolar II disorders - Results with the Méhes Scale.

    Science.gov (United States)

    Berecz, Hajnalka; Csábi, Györgyi; Jeges, Sára; Herold, Róbert; Simon, Maria; Halmai, Tamás; Trixler, Dániel; Hajnal, András; Tóth, Ákos Levente; Tényi, Tamás

    2017-03-01

    Minor physical anomalies (MPAs) are external markers of abnormal brain development, so the more common appearence of these signs among bipolar I and bipolar II patients can confirm the possibility of a neurodevelopmental deficit in these illnesses. The aim of the present study was to investigate the rate and topological profile of minor physical anomalies in patients with bipolar I and - first in literature - with bipolar II disorders compared to matched healthy control subjects. Using a list of 57 minor physical anomalies (the Méhes Scale), 30 bipolar I and 30 bipolar II patients, while as a comparison 30 matched healthy control subjects were examined. Significant differences were detected between the three groups comparing the total number of minor physical anomalies, minor malformations and phenogenetic variants and in the cases of the ear and the mouth regions. The individual analyses of the 57 minor physical anomalies by simultaneous comparison of the three groups showed, that in the cases of furrowed tongue and high arched palate were significant differences between the three groups. The results can promote the concept, that a neurodevelopmental deficit may play a role in the etiology of both bipolar I and bipolar II disorders.

  14. A different perspective on bipolar disorder? : epidemiology, consequences, concept, and recognition of bipolar spectrum disorder in the general population

    NARCIS (Netherlands)

    Regeer, Eline Janet

    2008-01-01

    Bipolar disorder, or manic-depressive illness, is a mood disorder in which episodes of mania, hypomania and depression occur in alternation with intervals of normal mood. Bipolar disorder is typically a recurrent illness and may have serious consequences such as poor social and occupational function

  15. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    Science.gov (United States)

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  16. Analysis of bioavailable Ge in agricultural and mining-affected-soils in Freiberg area (Saxony, Germany)

    Science.gov (United States)

    Wiche, Oliver; Székely, Balázs; Kummer, Nicolai-Alexeji; Heinemann, Ute; Heilmeier, Hermann

    2014-05-01

    Germanium (Ge) concentrations in different soil fraction were investigated using a sequential selective dissolution analysis and a rhizosphere-based single-step extraction method for the identification of Ge-bearing soil fractions and prediction of bioavailability of Ge in soil to plants. About 50 soil samples were collected from various soil depths (horizons A and B) and study sites with different types of land use (dry and moist grassland, arable land, mine dumps) in Freiberg area (Saxony, Germany). Ge has been extracted in six soil fractions: mobile fraction, organic matter and sulfides, Mn- and Fe-oxides (amorphous and crystalline), and kaolinite and phytoliths, and residual fraction. The rhizosphere-based method included a 7-day-long extraction sequence with various organic acids like citric acid, malic acid and acetic acid. For the residue the aforementioned sequential extraction has been applied. The Ge-content of the samples have been measured with ICP-MS using rhodium internal standard and two different soil standards. Total Ge concentrations were found to be in the range of 1.6 to 5.5 ppm with highest concentrations on the tailing site in the mining area of Altenberg. The mean Ge concentration in agriculturally used soils was 2.6 ± 0.67 ppm, whereas the maximum values reach 2.9 ± 0.64 ppm and 3.2 ± 0.67 ppm in Himmelsfürst and in a grassland by the Mulde river, respectively. With respect to the fractions, the vast majority of Ge is contained in the last three fractions, indicating that the bioavailable Ge is typically low in the samples. On the other hand at the soil horizons A at the aforementioned two sites characterised by high total Ge, together with that of Reiche Zeche mine dump have also the highest concentrations of Ge in the first three fractions, reaching levels of 1.74 and 0.98 ppm which account for approximately 40% of the total Ge content. Ge concentrations of soil samples extracted with 0.01 or 0.1 M citric acid and malic acid were

  17. Amorphous Diamond MEMS and Sensors

    Energy Technology Data Exchange (ETDEWEB)

    SULLIVAN, JOHN P.; FRIEDMANN, THOMAS A.; ASHBY, CAROL I.; DE BOER, MAARTEN P.; SCHUBERT, W. KENT; SHUL, RANDY J.; HOHLFELDER, ROBERT J.; LAVAN, D.A.

    2002-06-01

    This report describes a new microsystems technology for the creation of microsensors and microelectromechanical systems (MEMS) using stress-free amorphous diamond (aD) films. Stress-free aD is a new material that has mechanical properties close to that of crystalline diamond, and the material is particularly promising for the development of high sensitivity microsensors and rugged and reliable MEMS. Some of the unique properties of aD include the ability to easily tailor film stress from compressive to slightly tensile, hardness and stiffness 80-90% that of crystalline diamond, very high wear resistance, a hydrophobic surface, extreme chemical inertness, chemical compatibility with silicon, controllable electrical conductivity from insulating to conducting, and biocompatibility. A variety of MEMS structures were fabricated from this material and evaluated. These structures included electrostatically-actuated comb drives, micro-tensile test structures, singly- and doubly-clamped beams, and friction and wear test structures. It was found that surface micromachined MEMS could be fabricated in this material easily and that the hydrophobic surface of the film enabled the release of structures without the need for special drying procedures or the use of applied hydrophobic coatings. Measurements using these structures revealed that aD has a Young's modulus of {approx}650 GPa, a tensile fracture strength of 8 GPa, and a fracture toughness of 8 MPa{center_dot}m {sup 1/2}. These results suggest that this material may be suitable in applications where stiction or wear is an issue. Flexural plate wave (FPW) microsensors were also fabricated from aD. These devices use membranes of aD as thin as {approx}100 nm. The performance of the aD FPW sensors was evaluated for the detection of volatile organic compounds using ethyl cellulose as the sensor coating. For comparable membrane thicknesses, the aD sensors showed better performance than silicon nitride based sensors. Greater

  18. Phase transformation in Pb:GeSbTe chalcogenide films

    Science.gov (United States)

    Kumar, J.; Kumar, P.; Ahmad, M.; Chander, R.; Thangaraj, R.; Sathiaraj, T. S.

    2008-11-01

    A comprehensive analysis on the amorphous to crystalline phase transformation in Pb:GeSbTe chalcogenide alloy has been discussed. The structure identified with X-ray measurements has been discussed in relation to thermal analysis carried out on bulk samples. Optical constants have been calculated in the 350 to 800 nm wavelength range, using Fresnel's equation. The effect of Pb substitution on the optical contrast in terms of change in reflectivity and optical parameters (viz. refractive index, extinction coefficient) has been discussed. Marginal decrease in the optical contrast has been observed with a small increase in Pb content, which is effective to maintain the sufficient signal to noise ratio for optical phase-change storage.

  19. Polyphosphonium-based ion bipolar junction transistors.

    Science.gov (United States)

    Gabrielsson, Erik O; Tybrandt, Klas; Berggren, Magnus

    2014-11-01

    Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e., ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2 μm, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example, addressable drug-delivery devices.

  20. The last deglaciation: timing the bipolar seesaw

    Directory of Open Access Journals (Sweden)

    J. B. Pedro

    2011-06-01

    Full Text Available Precise information on the relative timing of north-south climate variations is a key to resolving questions concerning the mechanisms that force and couple climate changes between the hemispheres. We present a new composite record made from five well-resolved Antarctic ice core records that robustly represents the timing of regional Antarctic climate change during the last deglaciation. Using fast variations in global methane gas concentrations as time markers, the Antarctic composite is directly compared to Greenland ice core records, allowing a detailed mapping of the inter-hemispheric sequence of climate changes. Consistent with prior studies the synchronized records show that warming (and cooling trends in Antarctica closely match cold (and warm periods in Greenland on millennial timescales. For the first time, we also identify a sub-millennial component to the inter-hemispheric coupling. Within the Antarctic Cold Reversal the strongest Antarctic cooling occurs during the pronounced northern warmth of the Bølling. Warming then resumes in Antarctica, potentially as early as the Intra-Allerød Cold Period, but with dating uncertainty that could place it as late as the onset of the Younger Dryas stadial. There is little-to-no time lag between climate transitions in Greenland and opposing changes in Antarctica. Our results lend support to fast acting inter-hemispheric coupling mechanisms, including recently proposed bipolar atmospheric teleconnections and/or rapid bipolar ocean teleconnections.

  1. Bipolar mood cycles and lunar tidal cycles.

    Science.gov (United States)

    Wehr, T A

    2017-01-24

    In 17 patients with rapid cycling bipolar disorder, time-series analyses detected synchronies between mood cycles and three lunar cycles that modulate the amplitude of the moon's semi-diurnal gravimetric tides: the 14.8-day spring-neap cycle, the 13.7-day declination cycle and the 206-day cycle of perigee-syzygies ('supermoons'). The analyses also revealed shifts among 1:2, 1:3, 2:3 and other modes of coupling of mood cycles to the two bi-weekly lunar cycles. These shifts appear to be responses to the conflicting demands of the mood cycles' being entrained simultaneously to two different bi-weekly lunar cycles with slightly different periods. Measurements of circadian rhythms in body temperature suggest a biological mechanism through which transits of one of the moon's semi-diurnal gravimetric tides might have driven the patients' bipolar cycles, by periodically entraining the circadian pacemaker to its 24.84-h rhythm and altering the pacemaker's phase-relationship to sleep in a manner that is known to cause switches from depression to mania.Molecular Psychiatry advance online publication, 24 January 2017; doi:10.1038/mp.2016.263.

  2. High-performance silicon nanowire bipolar phototransistors

    Science.gov (United States)

    Tan, Siew Li; Zhao, Xingyan; Chen, Kaixiang; Crozier, Kenneth B.; Dan, Yaping

    2016-07-01

    Silicon nanowires (SiNWs) have emerged as sensitive absorbing materials for photodetection at wavelengths ranging from ultraviolet (UV) to the near infrared. Most of the reports on SiNW photodetectors are based on photoconductor, photodiode, or field-effect transistor device structures. These SiNW devices each have their own advantages and trade-offs in optical gain, response time, operating voltage, and dark current noise. Here, we report on the experimental realization of single SiNW bipolar phototransistors on silicon-on-insulator substrates. Our SiNW devices are based on bipolar transistor structures with an optically injected base region and are fabricated using CMOS-compatible processes. The experimentally measured optoelectronic characteristics of the SiNW phototransistors are in good agreement with simulation results. The SiNW phototransistors exhibit significantly enhanced response to UV and visible light, compared with typical Si p-i-n photodiodes. The near infrared responsivities of the SiNW phototransistors are comparable to those of Si avalanche photodiodes but are achieved at much lower operating voltages. Compared with other reported SiNW photodetectors as well as conventional bulk Si photodiodes and phototransistors, the SiNW phototransistors in this work demonstrate the combined advantages of high gain, high photoresponse, low dark current, and low operating voltage.

  3. Loopy: The Political Ontology of Bipolar Disorder

    Directory of Open Access Journals (Sweden)

    RACHEL JANE LIEBERT

    2013-01-01

    Full Text Available This essay is at once a critical analysis, an experiment in form, and – with some irony – a cautionary tale. Triggered by the inclusion of prodromal diagnoses in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, and the recent call by the United States’ (U.S. Obama administration for increased mental health screening, I argue that shifts toward identifying and intervening on one’s potential madness, or risk, circulate with/in the contemporary U.S. climate of intensified discipline and terror, and use Bipolar Disorder as a site to critically explore how and with what implications this circulation occurs. Specifically, I weave Massumi’s ‘political ontology of threat’ with the narrative of a woman diagnosed with Bipolar Disorder in order to trace the pre-emptive politics and affective logic of a risk-based approach to madness. I contend that the diagnosing and drugging of potential is a self-perpetuating loop that is personally and politically harmful, and consider alternatives to this burgeoning practice.

  4. Base Transport and Vertical Profile Engineering in SILICON/SILICON(1-X) Germanium(x)/silicon Heterojunction Bipolar Transistors

    Science.gov (United States)

    Prinz, Erwin Josef

    1992-01-01

    Recent advances in low-temperature epitaxial growth of strained silicon-germanium alloys on silicon substrates allow bandgap engineering in silicon-based devices, with profound consequences for device design. In this thesis the improved control by Rapid Thermal Chemical Vapor Deposition of the vertical profile of a Si/Si_{1-x}Ge _{x}/Si heterojunction bipolar transistor (HBT) is used to study the effect of the shape of the conduction band in the base on device performance. Near-ideal base currents in Si/Si_ {1-x}Ge_{x}/Si HBT's, limited by hole injection into the emitter, are achieved using a non-ultra-high vacuum (UHV) technique for the first time, proving that high-lifetime Si_{1-x}Ge _{x} material can be fabricated using processes compatible with standard silicon technology. Graded-base Si/Si_{1-x}Ge_{x} /Si HBT's are fabricated in a non-UHV epitaxial technology for the first time, and their electrical characteristics are modeled analytically. The formation of parasitic potential barriers for electrons in the base of HBT's resulting from base dopant outdiffusion or non-abrupt interfaces is studied, together with the concurrent degradation of the electrical performance of the devices. This deleterious effect is especially severe in devices with narrow, heavily doped bases fabricated in an integrated circuit (IC) process because of the thermal budget employed. To alleviate this problem, intrinsic Si_{1-x}Ge_{x}^acer layers can be inserted on both sides of the base to greatly improve device performance. The tradeoff between the common-emitter current gain beta and the Early voltage V_{A} (output resistance) in heterojunction bipolar transistors is investigated for the first time. This tradeoff is important for analog application of HBT's, and it is shown that thin, narrow -gap layers in the base close to the base-collector junction reduce the Early effect dramatically leading to a high Early voltage. It is further demonstrated that even small amounts of dopant

  5. Pulsed laser annealing of highly doped Ge:Sb layers deposited on different substrates

    Science.gov (United States)

    Batalov, R. I.; Bayazitov, R. M.; Faizrakhmanov, I. A.; Lyadov, N. M.; Shustov, V. A.; Ivlev, G. D.

    2016-10-01

    Germanium (Ge) is a promising material for micro- and optoelectronics to produce high speed field-effect transistors, photodetectors, light-emitting diodes and lasers. For such applications tensile-strained and/or highly n-doped Ge layers are needed. The authors have performed the formation of such layers by ion-beam sputtering of composite Sb/Ge target, deposition of thin amorphous Ge:Sb films (~200 nm thick) on different substrates (c-Si, c-Al2O3, α-SiO2) followed by pulsed laser annealing (PLA) for their crystallization and Sb dopant activation. Structural, electrical and optical characterization of Ge:Sb films was carried out using scanning electron microscopy, x-ray diffraction, micro-Raman spectroscopy, secondary ion mass spectrometry methods and by measuring sheet resistance, carrier concentration and photoluminescence. The obtained polycrystalline n-Ge:Sb layers (N Sb ~ 1 at.%) are characterized by increased values of tensile strain (up to 1%) and homogenious Sb dopant distribution within layer thickness. The electrical measurements at 300 K revealed the low sheet resistance (up to 40 Ω/□) and extremely high electron concentration (up to 5.5  ×  1020 cm-3) in Ge:Sb/SiO2 samples that indicated full electrical activation of Sb dopant on SiO2 substrate. The increased values of tensile strain and electron concentration of Ge:Sb films on α-SiO2 are explained by low values of thermal conductivity and thermal expansion coefficients of quartz substrate.

  6. Regrowth characteristics of SiGe/Si by IBIEC and SPEG

    Energy Technology Data Exchange (ETDEWEB)

    Awane, K.; Kokubo, Y.; Yomogida, M. [Graduate School of Engineering, Hosei University, Koganei, Tokyo 184-8584 (Japan); Nishimura, T. [Reseach Center of Ion Beam Technology, Hosei University, Koganei, Tokyo 184-8584 (Japan); Yamamoto, Y., E-mail: hiro@edl.ei.hosei.ac.jp [Graduate School of Engineering, Hosei University, Koganei, Tokyo 184-8584 (Japan)

    2013-07-15

    Single crystalline Si{sub 1−x}Ge{sub x}/Si with three kinds of Ge contents (x: 0.05, 0.1, and 0.2) with thicknesses of 400–440 nm were amorphized by 500 keV (x: 0.05 and 0.1) and 600 keV (x: 0.2) Ge ion beam bombardment to a fluence of 1.0 × 10{sup 16} ions/cm{sup 2} at room temperature. The regrowth behavior of the damaged layers were compared between ion beam induced epitaxial crystallization (IBIEC) by 2.0 MeV Ge ions at 300 °C to fluences of 1.0–3.0 × 10{sup 16} ions/cm{sup 2} and solid phase epitaxial growth (SPEG) carried out in a flowing N{sub 2} ambient for up to 40 min at 600 °C. Rutherford backscattering spectroscopy (RBS) with channeling techniques revealed that crystallinity improvement by IBIEC tended to be saturated with increasing fluence while crystallinity improvement by SPEG was proceeded with increasing annealing time and relatively high quality SiGe layers were obtained. Crystallinity improvement was more rapid and pronounced for SiGe with higher Ge concentration both in IBIEC and SPEG. In contrast to the case of SPEG at 600 °C, transmission electron microscope (TEM) image in SiGe treated by IBIEC showed that bunches of dislocation loops remained as islands surrounded by single crystalline lattice layers image, leading to the high RBS aligned yield even after completion of the layer-by-layer regrowth.

  7. Structural Variations in Amorphous Silicon and Germanium: a Vibrational Spectroscopy Study

    Science.gov (United States)

    Maley, Nagendranath

    Variations in short range structural order in the tetrahedral amorphous semiconductors Si and Ge have been studied by means of vibrational spectroscopy. Short range order (SRO) in in a-Si and a-Ge can be described by bond length, bond angle and dihedral angle distributions. While the existence of SRO in amorphous (a-) Si and Ge has been known for a long time, it was believed until recently that it was not variable. This notion was, in part, based on the results of conventional diffraction studies which showed negligible changes in the radial distribution function for different samples. Thus the observed variations in physical properties as a function of sample preparation conditions were attributed to extrinsic effects such as voids. However, recent studies in this laboratory showed that SRO is variable, primarily through modifications of P((THETA)), the bond angle distribution, and that Raman scattering can be used to measure small variations in (DELTA)(THETA), the width of P((THETA)). Subsequent studies here and elsewhere have shown strong correlations between Raman and various physical properties suggesting that variations in SRO have important consequences on electronic as well as vibrational properties of both a-Si and a-Ge. A detailed study has been carried out to investigate the extent of variation in SRO and the effect of preparation conditions. The results show the bond angle distribution width to be very sensitive to preparation conditions, particularly, temperature, bombardment and hydrogen incorporation. Phonon spectra of highly ordered and highly disordered samples of a-Ge have been obtained by means of inelastic neutron scattering. Detailed comparisons between theory and experiment for phonon as well as Raman spectra show qualitative agreement. The discrepancies provide suggestions for further improvements in theory. Estimates from a combination of optical, Raman and RDF data and comparisons between theory and experiment suggest that (DELTA

  8. Effect of Ion Bombardment on the Growth and Properties of Hydrogenated Amorphous Silicon-Germanium Alloys

    Science.gov (United States)

    Perrin, Jérôme; Takeda, Yoshihiko; Hirano, Naoto; Matsuura, Hideharu; Matsuda, Akihisa

    1989-01-01

    We report a systematic investigation of the effect of ion bombardment during the growth of amorphous silicon-germanium alloy films from silane and germane rf-glow discharge. Independent control of the plasma and the ion flux and energy is obtained by using a triode configuration. The ion contribution to the total deposition rate can reach 20% on negatively biased substrates. Although the Si and Ge composition of the film does not depend on the ion flux and energy, the optical, structural and electronic properties are drastically modified at low deposition temperatures when the maximum ion energy increases up to 50 eV, and remain constant above 50 eV. For a Ge atomic concentration of 37% and a temperature of 135°C, the optical gap decreases from 1.67 to 1.45 eV. This is correlated with a modification of hydrogen bonding configurations. Silicon dihydride sites disappear and preferential attachment of hydrogen to silicon is reduced in favour of germanium. Moreover the photoconductivity increases which shows that ion bombardment is a key parameter to optimize the quality of low band gap amorphous silicon-germanium alloys.

  9. Towards a fully functional integrated photonic-electronic platform via a single SiGe growth step

    Science.gov (United States)

    Littlejohns, Callum G.; Dominguez Bucio, Thalia; Nedeljkovic, Milos; Wang, Hong; Mashanovich, Goran Z.; Reed, Graham T.; Gardes, Frederic Y.

    2016-01-01

    Silicon-germanium (Si1-xGex) has become a material of great interest to the photonics and electronics industries due to its numerous interesting properties including higher carrier mobilities than Si, a tuneable lattice constant, and a tuneable bandgap. In previous work, we have demonstrated the ability to form localised areas of single crystal, uniform composition SiGe-on-insulator. Here we present a method of simultaneously growing several areas of SiGe-on-insulator on a single wafer, with the ability to tune the composition of each localised SiGe area, whilst retaining a uniform composition in that area. We use a rapid melt growth technique that comprises of only a single Ge growth step and a single anneal step. This innovative method is key in working towards a fully integrated photonic-electronic platform, enabling the simultaneous growth of multiple compositions of device grade SiGe for electro-absorption optical modulators operating at a range of wavelengths, photodetectors, and bipolar transistors, on the same wafer. This is achieved by modifying the structural design of the SiGe strips, without the need to modify the growth conditions, and by using low cost, low thermal-budget methods.

  10. Twelve-bit 20-GHz reduced size pipeline accumulator in 0.25 μm SiGe:C technology for direct digital synthesiser applications

    DEFF Research Database (Denmark)

    Jensen, Brian Sveistrup; Khafaji, M. M.; Johansen, T. K.;

    2012-01-01

    This article presents a 20 GHz, 12-bit pipeline accumulator with a reduced number of registers, suitable for direct digital synthesiser (DDS) applications. The accumulator is implemented in the IHP SG25H1 (0.25 μm) SiGe:C technology featuring heterojunction bipolar transistors (HBTs) with Ft......), the implemented 12-bit accumulator reduces the number of registers by 55% and the power by approximately 32%, while obtaining the highest clock frequency for SiGe:C accumulators intended for DDS applications....

  11. Meta-Analysis of Amygdala Volumes in Children and Adolescents with Bipolar Disorder

    Science.gov (United States)

    Pfeifer, Jonathan C.; Welge, Jeffrey; Strakowski. Stephen M.; Adler, Caleb M.; Delbello, Melissa P.

    2008-01-01

    The size of amygdala of bipolar youths and adults is investigated using neuroimaging studies. Findings showed that smaller volumes of amygdala were observed in youths with bipolar youths compared with children and adolescents without bipolar disorder. The structural amygdala abnormalities in bipolar youths are examined further.

  12. Transtorno bipolar do humor e gênero Bipolar affective disorder and gender

    Directory of Open Access Journals (Sweden)

    Rodrigo da Silva Dias

    2006-01-01

    Full Text Available Embora o transtorno bipolar (TB ocorra quase igualmente em ambos os sexos, a fenomenologia e o curso da doença diferem no homem e na mulher. No entanto, há evidências de que mulheres bipolares, mais que os homens, apresentariam início mais tardio (em especial na quinta década de vida, ciclagem rápida, mais episódios depressivos, mais mania disfórica que eufórica, estados mistos e evolução do tipo bipolar II, ainda que os achados nem sempre sejam consistentes. Embora o risco de comorbidades no TB inclua, para ambos os gêneros, abuso de álcool e drogas, homens bipolares teriam maior probabilidade de ser alcoolistas, não procurar tratamento e de se suicidar. Hipóteses sugeridas para explicar tais diferenças variam daquelas centradas em aspectos culturais ou psicológicos para as que focalizam os sistemas hormonais, como os esteróides gonadais ou o eixo tireoidiano, e até mesmo a anatomia cerebral. A influência do ciclo reprodutivo (ciclo menstrual, gravidez e menopausa sobre as opções terapêuticas no tratamento do TB é apresentada na última parte desta revisão.Although the bipolar disorder (BD occurs almost with the same frequency in both genders, the phenomenology and the outcome of the illness differ between them. Nevertheless, there is evidence that women with BD show, more than men, delayed beginning, especially in their fifth decade, more rapid cycling outcome, more depressive episodes, more dysphoric mania, more mixed states and more BD type II. Even so, the findings are not always consistent. Although the risk of comorbidities in BD includes, for both the sorts, excessive alcoholic consumption and drugs, bipolar men would have greater probability of being alcohol dependent, of not seeking treatment and of committing suicide. Suggested hypotheses to explain such differences vary from those centered in cultural or psychological aspects to those that focus on the steroids hormones, and other hormones such as cortisol

  13. Epi-cleaning of Ge/GeSn heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Di Gaspare, L.; Sabbagh, D.; De Seta, M.; Sodo, A. [Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, 00146 Rome (Italy); Wirths, S.; Buca, D. [Peter Grünberg Institute 9 and JARA-Fundamentals of Future Information Technologies, Forschungszentrum Juelich, Juelich 52425 (Germany); Zaumseil, P. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); BTU Cottbus, Konrad-Zuse Str. 1, 03046 Cottbus (Germany); Capellini, G., E-mail: capellini@ihp-microelectronics.com [Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, 00146 Rome (Italy); IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany)

    2015-01-28

    We demonstrate a very-low temperature cleaning technique based on atomic hydrogen irradiation for highly (1%) tensile strained Ge epilayers grown on metastable, partially strain relaxed GeSn buffer layers. Atomic hydrogen is obtained by catalytic cracking of hydrogen gas on a hot tungsten filament in an ultra-high vacuum chamber. X-ray photoemission spectroscopy, reflection high energy electron spectroscopy, atomic force microscopy, secondary ion mass spectroscopy, and micro-Raman showed that an O- and C-free Ge surface was achieved, while maintaining the same roughness and strain condition of the as-deposited sample and without any Sn segregation, at a process temperature in the 100–300 °C range.

  14. V-Ge-Cu system

    Energy Technology Data Exchange (ETDEWEB)

    Savitskij, E.M.; Efimov, Yu.V.; Bodak, O.I.; Kharchenko, O.I.; Shomova, N.A.; Frolova, T.M.

    By the methods of microscopic, X-ray phase analyses, X-ray spectral microanalysis as well as by measurement of Tsub(C) and phase lattice parameters the structure of the vanadium-region of the V-Ge ternary system (up to 40 at.%) - Cu(up to 90 at.%) is studied and isothermal cross section at 800 deg C is plotted. In the studied region solid solutions on the base of vanadium, copper and V/sub 3/Ge and V/sub 5/Ge/sub 3/ compounds are in phase equilibria. The solid solution on the vanadium base in ternary alloys practically does not possess superconductivity at the temperature over 4.2 K. Tsub(C) of V/sub 3/Ge saturated with copper decreases up to 5.3-5.6 K depending on treatment conditions and alloys composition. The superspeed quenching from molten state and the consequent low-temperature tempering of ternary alloys can increase V/sub 3/Ge Tsub(C) up to 6-6.7 K.

  15. Structural Evolution of Compressing Amorphous Ice

    Institute of Scientific and Technical Information of China (English)

    WANG Yan; DONG Shun-Le

    2007-01-01

    Molecular dynamics simulation is employed to study structural evolution during compressing low density amorphous ice from one atmosphere to 2.5 GPa.The calculated results show that high density amorphous ice is formed under intermediate pressure of about 1.0 GPa and O-O-O angle ranges from about 83°to 113°and O-H……O is bent from 112°to 160°.The very high density amorphous ice is also formed under the pressure larger than 1.4 GPa and interstitial molecules are found in 0.3-0.4 (A) just beyond the nearest O-O distance.Low angle O-H……O disappears and it is believed that these hydrogen bonds are broken or re-bonded under high pressures.

  16. Towards upconversion for amorphous silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    de Wild, J.; Rath, J.K.; Schropp, R.E.I. [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, Nanophotonics, P.O. Box 80000, 3508 TA Utrecht (Netherlands); Meijerink, A. [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, Condensed Matter and Interfaces, P.O. Box 80000, 3508 TA Utrecht (Netherlands); van Sark, W.G.J.H.M. [Utrecht University, Copernicus Institute for Sustainable Development and Innovation, Science, Technology and Society, Heidelberglaan 2, 3584 CS Utrecht (Netherlands)

    2010-11-15

    Upconversion of subbandgap light of thin film single junction amorphous silicon solar cells may enhance their performance in the near infrared (NIR). In this paper we report on the application of the NIR-vis upconverter {beta}-NaYF{sub 4}:Yb{sup 3+}(18%) Er{sup 3+}(2%) at the back of an amorphous silicon solar cell in combination with a white back reflector and its response to infrared irradiation. Current-voltage measurements and spectral response measurements were done on experimental solar cells. An enhancement of 10 {mu}A/cm{sup 2} was measured under illumination with a 980 nm diode laser (10 mW). A part of this was due to defect absorption in localized states of the amorphous silicon. (author)

  17. Nanosecond laser-induced phase transitions in pulsed laser deposition-deposited GeTe films

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xinxing, E-mail: xinxing.sun@iom-leipzig.de; Thelander, Erik; Lorenz, Pierre; Gerlach, Jürgen W.; Decker, Ulrich; Rauschenbach, Bernd [Leibniz Institute of Surface Modification, Permoserstr. 15, D-04318, Leipzig (Germany)

    2014-10-07

    Phase transformations between amorphous and crystalline states induced by irradiation of pulsed laser deposition grown GeTe thin films with nanosecond laser pulses at 248 nm and pulse duration of 20 ns are studied. Structural and optical properties of the Ge-Te phase-change films were studied by X-ray diffraction and optical reflectivity measurements as a function of the number of laser pulses between 0 and 30 pulses and of the laser fluence up to 195 mJ/cm². A reversible phase transition by using pulse numbers ≥ 5 at a fluence above the threshold fluence between 11 and 14 mJ/cm² for crystallization and single pulses at a fluence between 162 and 182 mJ/cm² for amorphization could be proved. For laser fluences from 36 up to 130 mJ/cm², a high optical contrast of 14.7% between the amorphous and crystalline state is measured. A simple model is used that allows the discussion on the distribution of temperature in dependency on the laser fluence.

  18. New Approaches to the Computer Simulation of Amorphous Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Fernando Alvarez-Ramirez

    2011-04-01

    Full Text Available In this work we review our new methods to computer generate amorphous atomic topologies of several binary alloys: SiH, SiN, CN; binary systems based on group IV elements like SiC; the GeSe2 chalcogenide; aluminum-based systems: AlN and AlSi, and the CuZr amorphous alloy. We use an ab initio approach based on density functionals and computationally thermally-randomized periodically-continued cells with at least 108 atoms. The computational thermal process to generate the amorphous alloys is the undermelt-quench approach, or one of its variants, that consists in linearly heating the samples to just below their melting (or liquidus temperatures, and then linearly cooling them afterwards. These processes are carried out from initial crystalline conditions using short and long time steps. We find that a step four-times the default time step is adequate for most of the simulations. Radial distribution functions (partial and total are calculated and compared whenever possible with experimental results, and the agreement is very good. For some materials we report studies of the effect of the topological disorder on their electronic and vibrational densities of states and on their optical properties.

  19. Mental imagery as an emotional amplifier: application to bipolar disorder.

    Science.gov (United States)

    Holmes, Emily A; Geddes, John R; Colom, Francesc; Goodwin, Guy M

    2008-12-01

    Cognitions in the form of mental images have a more powerful impact on emotion than their verbal counterparts. This review synthesizes the cognitive science of imagery and emotion with transdiagnostic clinical research, yielding novel predictions for the basis of emotional volatility in bipolar disorder. Anxiety is extremely common in patients with bipolar disorder and is associated with increased dysfunction and suicidality, yet it is poorly understood and rarely treated. Mental imagery is a neglected aspect of bipolar anxiety although in anxiety disorders such as posttraumatic stress disorder and social phobia focusing on imagery has been crucial for the development of cognitive behavior therapy (CBT). In this review we present a cognitive model of imagery and emotion applied to bipolar disorder. Within this model mental imagery amplifies emotion, drawing on Clark's cyclical panic model [(1986). A cognitive approach to panic. Behaviour Research and Therapy, 24, 461-470]. We (1) emphasise imagery's amplification of anxiety (cycle one); (2) suggest that imagery amplifies the defining (hypo-) mania of bipolar disorder (cycle two), whereby the overly positive misinterpretation of triggers leads to mood elevation (escalated by imagery), increasing associated beliefs, goals, and action likelihood (all strengthened by imagery). Imagery suggests a unifying explanation for key unexplained features of bipolar disorder: ubiquitous anxiety, mood instability and creativity. Introducing imagery has novel implications for bipolar treatment innovation--an area where CBT improvements are much-needed.

  20. Broadening the diagnosis of bipolar disorder: benefits vs. risks

    Science.gov (United States)

    STRAKOWSKI, STEPHEN M.; FLECK, DAVID E.; MAJ, MARIO

    2011-01-01

    There is considerable debate over whether bipolar and related disorders that share common signs and symptoms, but are currently defined as distinct clinical entities in DSM-IV and ICD-10, may be better characterized as falling within a more broadly defined “bipolar spectrum”. With a spectrum view in mind, the possibility of broadening the diagnosis of bipolar disorder has been proposed. This paper discusses some of the rationale for an expanded diagnostic scheme from both clinical and research perspectives in light of potential drawbacks. The ultimate goal of broadening the diagnosis of bipolar disorder is to help identify a common etiopathogenesis for these conditions to better guide treatment. To help achieve this goal, bipolar researchers have increasingly expanded their patient populations to identify objective biological or endophenotypic markers that transcend phenomenological observation. Although this approach has and will likely continue to produce beneficial results, the upcoming DSM-IV and ICD-10 revisions will place increasing scrutiny on psychiatry’s diagnostic classification systems and pressure to re-evaluate our conceptions of bipolar disorder. However, until research findings can provide consistent and converging evidence as to the validity of a broader diagnostic conception, clinical expansion to a dimensional bipolar spectrum should be considered with caution. PMID:21991268