WorldWideScience

Sample records for p-type conductivity continue

  1. P-type transparent conducting oxides

    Science.gov (United States)

    Zhang, Kelvin H. L.; Xi, Kai; Blamire, Mark G.; Egdell, Russell G.

    2016-09-01

    Transparent conducting oxides constitute a unique class of materials combining properties of electrical conductivity and optical transparency in a single material. They are needed for a wide range of applications including solar cells, flat panel displays, touch screens, light emitting diodes and transparent electronics. Most of the commercially available TCOs are n-type, such as Sn doped In2O3, Al doped ZnO, and F doped SnO2. However, the development of efficient p-type TCOs remains an outstanding challenge. This challenge is thought to be due to the localized nature of the O 2p derived valence band which leads to difficulty in introducing shallow acceptors and large hole effective masses. In 1997 Hosono and co-workers (1997 Nature 389 939) proposed the concept of ‘chemical modulation of the valence band’ to mitigate this problem using hybridization of O 2p orbitals with close-shell Cu 3d 10 orbitals. This work has sparked tremendous interest in designing p-TCO materials together with deep understanding the underlying materials physics. In this article, we will provide a comprehensive review on traditional and recently emergent p-TCOs, including Cu+-based delafossites, layered oxychalcogenides, nd 6 spinel oxides, Cr3+-based oxides (3d 3) and post-transition metal oxides with lone pair state (ns 2). We will focus our discussions on the basic materials physics of these materials in terms of electronic structures, doping and defect properties for p-type conductivity and optical properties. Device applications based on p-TCOs for transparent p-n junctions will also be briefly discussed.

  2. P-type conductivity in annealed strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Poole, Violet M.; Corolewski, Caleb D.; McCluskey, Matthew D., E-mail: mattmcc@wsu.edu [Department of Physics and Astronomy, Washington State University, Pullman, WA 99164-2814 (United States)

    2015-12-15

    Hall-effect measurements indicate p-type conductivity in bulk, single-crystal strontium titanate (SrTiO{sub 3}, or STO) samples that were annealed at 1200°C. Room-temperature mobilities above 100 cm{sup 2}/V s were measured, an order of magnitude higher than those for electrons (5-10 cm{sup 2}/V s). Average hole densities were in the 10{sup 9}-10{sup 10} cm{sup −3} range, consistent with a deep acceptor.

  3. Infrared Transparent Spinel Films with p -Type Conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, Charles F.; Exarhos, Gregory J.; Ferris, Kim F.; Engelhard, Mark H.; Stewart, Donald C.

    2001-11-29

    Spinel oxide films containing at least two transition metal cations were found to exhibit p-type conductivity with high optical transparency from the visible to wavelengths near 15 micrometers. Resistivities as low as 0.003 ohm-cm were measured on 100 nm thick rf sputter deposited films that contained nickel and cobalt. Optical spectra, Raman scattering and XPS measurements indicated the valency of nickel localized on octahedral sites within the spinel lattice determines these properties. Electronic band structure calculations corroborated the experimental results. A resistivity minimum was found at the composition NiCo2O4 deposited from aqueous or alcoholic solutions followed by subsequent annealing at 400 degrees C in air. Solution deposited films richer in nickel than this stoichiometry always were found to phase separate into nickel oxide and a spinel phase with concomitant loss in conductivity. However, the phase stability region could be extended to higher nickel contents when rf-sputter deposition techniques were used. Sputter deposited spinel films having a nickel to cobalt ratio less than 2 were found to exhibit the highest conductivity. Results suggest that the phase stability region for these materials can be extended through appropriate choice of deposition conditions. A possible mechanism that promotes high conductivity in this system is thought to be charge transfer between the resident di- and trivalent cations that may be assisted by the magnetic nature of the oxide film.

  4. Theoretical prediction of p-type transparent conductivity in Zn-doped TiO2.

    Science.gov (United States)

    Han, Xiaoping; Shao, Guosheng

    2013-06-28

    It is very difficult and yet extremely important to fill the wide technological gap in developing transparent conducting oxides (TCOs) that exhibit excellent p-type conducting characteristics. Here, on the basis of extensive first-principles calculations, we discover for the first time potentially promising p-type transparent conductivity in Zn-doped TiO2 under oxygen rich conditions. Efforts have been made to elaborate the effects of possible defects and their interaction with Zn doping on the p-type transparent conductivity. This work offers a fundamental road map for cost-effective development of p-type TCOs based on TiO2, which is a cheap and stable material system of large natural resources.

  5. Luminance behavior of lithium-doped ZnO nanowires with p-type conduction characteristics.

    Science.gov (United States)

    Ko, Won Bae; Lee, Jun Seok; Lee, Sang Hyo; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Park, Young Jun; Kim, Hyun Jung; Hong, Jin Pyo

    2013-09-01

    The present study describes the room-temperature cathodeluminescence (CL) and temperature-dependent photoluminescence (PL) properties of p-type lithium (Li)-doped zinc oxide (ZnO) nanowires (NWs) grown by hydrothermal doping and post-annealing processes. A ZnO thin film was used as a seed layer in NW growth. The emission wavelengths and intensities of undoped ZnO NWs and p-type Li-doped ZnO NWs were analyzed for comparison. CL and PL observations of post-annealed p-type Li-doped ZnO NWs clearly exhibited a dominant sharp band-edge emission. Finally, a n-type ZnO thin film/p-type annealed Li-doped ZnO NW homojunction diode was prepared to confirm the p-type conduction of annealed Li-doped ZnO NWs as well as the structural properties measured by transmission electron microscopy.

  6. Method for producing high carrier concentration p-Type transparent conducting oxides

    Science.gov (United States)

    Li, Xiaonan; Yan, Yanfa; Coutts, Timothy J.; Gessert, Timothy A.; Dehart, Clay M.

    2009-04-14

    A method for producing transparent p-type conducting oxide films without co-doping plasma enhancement or high temperature comprising: a) introducing a dialkyl metal at ambient temperature and a saturated pressure in a carrier gas into a low pressure deposition chamber, and b) introducing NO alone or with an oxidizer into the chamber under an environment sufficient to produce a metal-rich condition to enable NO decomposition and atomic nitrogen incorporation into the formed transparent metal conducting oxide.

  7. Enhanced thermopower and low thermal conductivity in p-type polycrystalline ZrTe5

    Science.gov (United States)

    Hooda, M. K.; Yadav, C. S.

    2017-07-01

    Thermoelectric properties of polycrystalline p-type ZrTe5 are reported in the temperature (T) range of 2-340 K. Thermoelectric power (S) is positive and reaches up to 458 μV/K at 340 K on increasing T. The value of Fermi energy 16 meV suggests a low carrier density of ≈9.5 × 1018 cm-3. A sharp anomaly in S data is observed at 38 K, which seems intrinsic to p-type ZrTe5. The thermal conductivity (κ) value is low (2 W/m K at T = 300 K) with major contribution from the lattice part. Electrical resistivity data show the metal to semiconductor transition at T ˜ 150 K and non-Arrhenius behavior in the semiconducting region. The figure of merit zT (0.026 at T = 300 K) is ˜63% higher than that of HfTe5 (0.016) and better than those of the conventional SnTe, p-type PbTe, and bipolar pristine ZrTe5 compounds.

  8. Enhanced photovoltaic effect of ruthenium complex-modified graphene oxide with P-type conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei, E-mail: jj_zw_js@sina.com.cn; Bai, Huicong; Zhang, Yu; Sun, Ying; Lin, Shen; Liu, Jian; Yang, Qi; Song, Xi-Ming, E-mail: songlab@lnu.edu.cn

    2014-10-15

    A graphene oxide nanocomposite with bis(1,10-phenanthroline)(N-(2-aminoethyl)-4-(4-methyl-2,2-bipyridine-4-yl) formamide) ruthenium (Ru(phen){sub 2}(bpy-NH{sub 2})(PF{sub 6}){sub 2}), a ruthenium complex, was synthesized by amidation reaction between amino group of the ruthenium complex and carboxyl group of GO. The as-prepared Ru(II)–GO composite was characterized by infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) absorption spectra, fluorescence spectra, surface photovoltage (SPV) spectrum and transient photovoltage (TPV) technology. This nanocomposite showed a typical p-type character and an enhanced photovoltaic effect at long timescale of about 3 × 10{sup −3} s compared to GO alone. A reversible rise/decay of the photocurrent in response to the on/off illumination step was also observed in a photoelectrochemical cell of the Ru(II)–GO composite. The photocurrent response of the Ru(II)–GO film was remarkably higher than that of GO film. Therefore, this Ru(II)–GO composite is believed to be a promising p-type photoelectric conversion material for further photovoltaic applications. - Highlights: • A new dye-sensitized graphene oxide nanocomposite was reported. • A photo-induced charge transfer process in this nanocomposite was confirmed. • This composite showed a typical p-type conductivity. • This composite showed an enhanced photovoltaic effect at a long timescale.

  9. Atomic layer deposition of undoped TiO2 exhibiting p-type conductivity.

    Science.gov (United States)

    Iancu, Andrei T; Logar, Manca; Park, Joonsuk; Prinz, Fritz B

    2015-03-11

    With prominent photocatalytic applications and widespread use in semiconductor devices, TiO2 is one of the most popular metal oxides. However, despite its popularity, it has yet to achieve its full potential due to a lack of effective methods for achieving p-type conductivity. Here, we show that undoped p-type TiO2 films can be fabricated by atomic layer deposition (ALD) and that their electrical properties can be controlled across a wide range using proper postprocessing anneals in various ambient environments. Hole mobilities larger than 400 cm(2)/(V·s) are accessible superseding the use of extrinsic doping, which generally produces orders of magnitude smaller values. Through a combination of analyses and experiments, we provide evidence that this behavior is primarily due to an excess of oxygen in the films. This discovery enables entirely new categories of TiO2 devices and applications, and unlocks the potential to improve existing ones. TiO2 homojunction diodes fabricated completely by ALD are developed as a demonstration of the utility of these techniques and shown to exhibit useful rectifying characteristics even with minimal processing refinement.

  10. Interstitial oxygen as a source of p-type conductivity in hexagonal manganites

    Science.gov (United States)

    Skjærvø, Sandra H.; Wefring, Espen T.; Nesdal, Silje K.; Gaukås, Nikolai H.; Olsen, Gerhard H.; Glaum, Julia; Tybell, Thomas; Selbach, Sverre M.

    2016-12-01

    Hexagonal manganites, h-RMnO3 (R=Sc, Y, Ho-Lu), have been intensively studied for their multiferroic properties, magnetoelectric coupling, topological defects and electrically conducting domain walls. Although point defects strongly affect the conductivity of transition metal oxides, the defect chemistry of h-RMnO3 has received little attention. We use a combination of experiments and first principles electronic structure calculations to elucidate the effect of interstitial oxygen anions, Oi, on the electrical and structural properties of h-YMnO3. Enthalpy stabilized interstitial oxygen anions are shown to be the main source of p-type electronic conductivity, without reducing the spontaneous ferroelectric polarization. A low energy barrier interstitialcy mechanism is inferred from Density Functional Theory calculations to be the microscopic migration path of Oi. Since the Oi content governs the concentration of charge carrier holes, controlling the thermal and atmospheric history provides a simple and fully reversible way of tuning the electrical properties of h-RMnO3.

  11. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B

  12. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B l

  13. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B l

  14. Perovskite Sr-doped LaCrO3 as a new p-type transparent conducting oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongliang; Du, Yingge; Papadogianni, Alexandra; Bierwagen, Oliver; Sallis, Shawn; Piper, Louis F. J.; Bowden, Mark E.; Shutthanandan, V.; Sushko, Petr; Chambers, Scott A.

    2015-09-16

    Transparent conducting oxides (TCOs) constitute a unique class of materials which combine the seemingly mutually exclusive properties of electrical conductivity and optical transparency in a single material. TCOs are useful for a wide range of applications including solar cells, displays, light emitting diodes and transparent electronics. Simple post-transition metal oxides such as ZnO, In2O3 and SnO2 are wide gap insulators in which the ionic character generates an oxygen 2p-derived valence band (VB) and a metal s-derived conduction band (CB), resulting in large optical band gaps (>3.0 eV) and excellent n-type conductivity when donor doped. In contrast, the development of efficient p-type TCOs remains a global materials challenge. Converting n-type oxides to p-type analogs by acceptor doping is extremely difficult and these materials display poor conductivity.

  15. Interstitial oxygen as a source of p-type conductivity in hexagonal manganites

    National Research Council Canada - National Science Library

    Sandra H Skjærvø; Espen T Wefring; Silje K Nesdal; Nikolai H Gaukås; Gerhard H Olsen; Julia Glaum; Thomas Tybell; Sverre M Selbach

    2016-01-01

      Hexagonal manganites, h-RMnO3 (R=Sc, Y, Ho-Lu), have been intensively studied for their multiferroic properties, magnetoelectric coupling, topological defects and electrically conducting domain walls...

  16. Electrical conduction and dielectric relaxation in p-type PVA/CuI polymer composite

    Directory of Open Access Journals (Sweden)

    M.H. Makled

    2013-11-01

    Full Text Available PVA/CuI polymer composite samples have been prepared and subjected to characterizations using FT-IR spectroscopy, DSC analysis, ac spectroscopy and dc conduction. The FT-IR spectral analysis shows remarkable variation of the absorption peak positions whereas DSC illustrates a little decrease of both glass transition temperature, Tg, and crystallization fraction, χ, with increasing CuI concentration. An increase of dc conductivity for PVA/CuI nano composite by increasing CuI concentration is recoded up to 15 wt%, besides it obeys Arhenuis plot with an activation energy in the range 0.54–1.32 eV. The frequency dependence of ac conductivity showed power law with an exponent 0.33 < s < 0.69 which predicts hopping conduction mechanism. The frequency dependence of both dielectric permittivity and dielectric loss obeys Debye dispersion relations in wide range of temperatures and frequency. Significant values of dipole relaxation time obtained which are thermally activated with activation energies in the range 0.33–0.87 eV. A significant value of hopping distance in the range 3.4–1.2 nm is estimated in agreement with the value of Bohr radius of the exciton.

  17. Electrical conduction and dielectric relaxation in p-type PVA/CuI polymer composite.

    Science.gov (United States)

    Makled, M H; Sheha, E; Shanap, T S; El-Mansy, M K

    2013-11-01

    PVA/CuI polymer composite samples have been prepared and subjected to characterizations using FT-IR spectroscopy, DSC analysis, ac spectroscopy and dc conduction. The FT-IR spectral analysis shows remarkable variation of the absorption peak positions whereas DSC illustrates a little decrease of both glass transition temperature, Tg , and crystallization fraction, χ, with increasing CuI concentration. An increase of dc conductivity for PVA/CuI nano composite by increasing CuI concentration is recoded up to 15 wt%, besides it obeys Arhenuis plot with an activation energy in the range 0.54-1.32 eV. The frequency dependence of ac conductivity showed power law with an exponent 0.33 < s < 0.69 which predicts hopping conduction mechanism. The frequency dependence of both dielectric permittivity and dielectric loss obeys Debye dispersion relations in wide range of temperatures and frequency. Significant values of dipole relaxation time obtained which are thermally activated with activation energies in the range 0.33-0.87 eV. A significant value of hopping distance in the range 3.4-1.2 nm is estimated in agreement with the value of Bohr radius of the exciton.

  18. Fabrication of p-type conductivity in SnO{sub 2} thin films through Ga doping

    Energy Technology Data Exchange (ETDEWEB)

    Tsay, Chien-Yie, E-mail: cytsay@fcu.edu.tw; Liang, Shan-Chien

    2015-02-15

    Highlights: • P-type Ga-doped SnO{sub 2} semiconductor films were prepared by sol-gel spin coating. • Optical bandgaps of the SnO{sub 2}:Ga films are narrower than that of the SnO{sub 2} film. • SnO{sub 2}:Ga films exhibited p-type conductivity as Ga doping content higher than 10%. • A p-n heterojunction composed of p-type SnO{sub 2}:Ga and n-type ZnO:Al was fabricated. - Abstract: P-type transparent tin oxide (SnO{sub 2}) based semiconductor thin films were deposited onto alkali-free glass substrates by a sol-gel spin-coating method using gallium (Ga) as acceptor dopant. In this study, we investigated the influence of Ga doping concentration ([Ga]/[Sn] + [Ga] = 0%, 5%, 10%, 15%, and 20%) on the structural, optical and electrical properties of SnO{sub 2} thin films. XRD analysis results showed that dried Ga-doped SnO{sub 2} (SnO{sub 2}:Ga) sol-gel films annealed in oxygen ambient at 520 °C for 1 h exhibited only the tetragonal rutile phase. The average optical transmittance of as-prepared thin film samples was higher than 87.0% in the visible light region; the optical band gap energy slightly decreased from 3.92 eV to 3.83 eV with increases in Ga doping content. Hall effect measurement showed that the nature of conductivity of SnO{sub 2}:Ga thin films changed from n-type to p-type when the Ga doping level was 10%, and when it was at 15%, Ga-doped SnO{sub 2} thin films exhibited the highest mean hole concentration of 1.70 × 10{sup 18} cm{sup -3}. Furthermore, a transparent p-SnO{sub 2}:Ga (Ga doping level of 15%)/n-ZnO:Al (Al doping level of 2%) heterojunction was fabricated on alkali-free glass. The I-V curve measurement for the p-n heterojunction diode showed a typical rectifying characteristic with a forward turn-on voltage of 0.65 V.

  19. Change in the electrical conductivity of SnO{sub 2} crystal from n-type to p-type conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Villamagua, Luis, E-mail: luis.villamagua@tyndall.ie [Grupo de Fisicoquímica de Materiales, Universidad Técnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Dipartimento di Ingegneria per l’Ambiente e il Territorio e Ingegneria Chimica, Università della Calabria, 87036 Rende (CS) (Italy); Stashans, Arvids [Grupo de Fisicoquímica de Materiales, Universidad Técnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Lee, Po-Ming; Liu, Yen-Shuo; Liu, Cheng-Yi [Department of Chemical and Materials Engineering, National Central University, Jhong-Li, Taiwan (China); Carini, Manuela [Dipartimento di Ingegneria per l’Ambiente e il Territorio e Ingegneria Chimica, Università della Calabria, 87036 Rende (CS) (Italy)

    2015-05-01

    Highlights: • Switch from n-type to p-type conductivity in SnO{sub 2} has been studied. • Computational DFT + U method where used. • X-ray diffraction and X-ray photoelectron spectroscopy where used. • Al- and N-codoped SnO{sub 2} compound shows stable p-type conductivity. • Low resistivity (3.657 × 10{sup −1} Ω cm) has been obtained. • High carrier concentration (4.858 × 10{sup 19} cm{sup −3}) has been obtained. - Abstract: The long-sought fully transparent technology will not come true if the n region of the p–n junction does not get as well developed as its p counterpart. Both experimental and theoretical efforts have to be used to study and discover phenomena occurring at the microscopic level in SnO{sub 2} systems. In the present paper, using the DFT + U approach as a main tool and the Vienna ab initio Simulation Package (VASP) we reproduce both intrinsic n-type as well as p-type conductivity in concordance to results observed in real samples of SnO{sub 2} material. Initially, an oxygen vacancy (1.56 mol% concentration) combined with a tin-interstitial (1.56 mol% concentration) scheme was used to achieve the n-type electrical conductivity. Later, to attain the p-type conductivity, crystal already possessing n-type conductivity, was codoped with nitrogen (1.56 mol% concentration) and aluminium (12.48 mol% concentration) impurities. Detailed explanation of structural changes endured by the geometry of the crystal as well as the changes in its electrical properties has been obtained. Our experimental data to a very good extent matches with the results found in the DFT + U modelling.

  20. Novel p-Type Conductive Semiconductor Nanocrystalline Film as the Back Electrode for High-Performance Thin Film Solar Cells.

    Science.gov (United States)

    Zhang, Ming-Jian; Lin, Qinxian; Yang, Xiaoyang; Mei, Zongwei; Liang, Jun; Lin, Yuan; Pan, Feng

    2016-02-10

    Thin film solar cells, due to the low cost, high efficiency, long-term stability, and consumer applications, have been widely applied for harvesting green energy. All of these thin film solar cells generally adopt various metal thin films as the back electrode, like Mo, Au, Ni, Ag, Al, graphite, and so forth. When they contact with p-type layer, it always produces a Schottky contact with a high contact potential barrier, which greatly affects the cell performance. In this work, we report for the first time to find an appropriate p-type conductive semiconductor film, digenite Cu9S5 nanocrystalline film, as the back electrode for CdTe solar cells as the model device. Its low sheet resistance (16.6 Ω/sq) could compare to that of the commercial TCO films (6-30 Ω/sq), like FTO, ITO, and AZO. Different from the traditonal metal back electrode, it produces a successive gradient-doping region by the controllable Cu diffusion, which greatly reduces the contact potential barrier. Remarkably, it achieved a comparable power conversion efficiency (PCE, 11.3%) with the traditional metal back electrode (Cu/Au thin films, 11.4%) in CdTe cells and a higher PCE (13.8%) with the help of the Au assistant film. We believe it could also act as the back electrode for other thin film solar cells (α-Si, CuInS2, CIGSe, CZTS, etc.), for their performance improvement.

  1. Effect of doping concentration on the conductivity and optical properties of p-type ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Trilok Kumar [Semiconductor Research Lab, Department of Physics, Gurukula Kangri University, Haridwar (India); Kumar, Vinod, E-mail: vinod.phy@gmail.com [Department of Physics, University of the Free State, Bloemfontein (South Africa); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, Bloemfontein (South Africa); Purohit, L.P., E-mail: proflppurohitphys@gmail.com [Semiconductor Research Lab, Department of Physics, Gurukula Kangri University, Haridwar (India)

    2016-01-01

    Nitrogen doped ZnO (NZO) thin films were synthesized on glass substrates by the sol–gel and spin coating method. Zinc acetate dihydrates and ammonium acetate were used as precursors for zinc and nitrogen, respectively. X-ray diffraction study showed that the thin films have a hexagonal wurtzite structure corresponding (002) peak for undoped and doped ZnO thin films. The transmittance of the films was above 80% and the band gap of the film varies from 3.21±0.03 eV for undoped and doped ZnO. The minimum resistivity of NZO thin films was obtained as 0.473 Ω cm for the 4 at% of nitrogen (N) doping with a mobility of 1.995 cm{sup 2}/V s. The NZO thin films showed p-type conductivity at 2 and 3 at% of N doping. The AC conductivity measurements that were carried out in the frequency range 10 kHz to 0.1 MHz showed localized conduction in the NZO thin films. These highly transparent ZnO films can be used as a possible window layer in solar cells.

  2. p-Type Transparent Conducting Oxide/n-Type Semiconductor Heterojunctions for Efficient and Stable Solar Water Oxidation.

    Science.gov (United States)

    Chen, Le; Yang, Jinhui; Klaus, Shannon; Lee, Lyman J; Woods-Robinson, Rachel; Ma, Jie; Lum, Yanwei; Cooper, Jason K; Toma, Francesca M; Wang, Lin-Wang; Sharp, Ian D; Bell, Alexis T; Ager, Joel W

    2015-08-05

    Achieving stable operation of photoanodes used as components of solar water splitting devices is critical to realizing the promise of this renewable energy technology. It is shown that p-type transparent conducting oxides (p-TCOs) can function both as a selective hole contact and corrosion protection layer for photoanodes used in light-driven water oxidation. Using NiCo2O4 as the p-TCO and n-type Si as a prototypical light absorber, a rectifying heterojunction capable of light driven water oxidation was created. By placing the charge separating junction in the Si using a np(+) structure and by incorporating a highly active heterogeneous Ni-Fe oxygen evolution catalyst, efficient light-driven water oxidation can be achieved. In this structure, oxygen evolution under AM1.5G illumination occurs at 0.95 V vs RHE, and the current density at the reversible potential for water oxidation (1.23 V vs RHE) is >25 mA cm(-2). Stable operation was confirmed by observing a constant current density over 72 h and by sensitive measurements of corrosion products in the electrolyte. In situ Raman spectroscopy was employed to investigate structural transformation of NiCo2O4 during electrochemical oxidation. The interface between the light absorber and p-TCO is crucial to produce selective hole conduction to the surface under illumination. For example, annealing to produce more crystalline NiCo2O4 produces only small changes in its hole conductivity, while a thicker SiOx layer is formed at the n-Si/p-NiCo2O4 interface, greatly reducing the PEC performance. The generality of the p-TCO protection approach is demonstrated by multihour, stable, water oxidation with n-InP/p-NiCo2O4 heterojunction photoanodes.

  3. Room temperature p-type conductivity and coexistence of ferroelectric order in ferromagnetic Li doped ZnO nanoparticles

    KAUST Repository

    Awan, Saif Ullah

    2014-10-28

    Memory and switching devices acquired new materials which exhibit ferroelectric and ferromagnetic order simultaneously. We reported multiferroic behavior in Zn1-yLiyO(0.00≤y≤0.10) nanoparticles. The analysis of transmission electron micrographs confirmed the hexagonal morphology and wurtzite crystalline structure. We investigated p-type conductivity in doped samples and measured hole carriers in range 2.4×1017/cc to 7.3×1017/cc for different Li contents. We found that hole carriers are responsible for long range order ferromagnetic coupling in Li doped samples. Room temperature ferroelectric hysteresis loops were observed in 8% and 10% Li doped samples. We demonstrated ferroelectric coercivity (remnant polarization) 2.5kV/cm (0.11 μC/cm2) and 2.8kV/cm (0.15 μC/cm2) for y=0.08 and y=0.10 samples. We propose that the mechanism of Li induced ferroelectricity in ZnO is due to indirect dipole interaction via hole carriers. We investigated that if the sample has hole carriers ≥5.3×1017/cc, they can mediate the ferroelectricity. Ferroelectric and ferromagnetic measurements showed that higher electric polarization and larger magnetic moment is attained when the hole concentration is larger and vice versa. Our results confirmed the hole dependent coexistence of ferromagnetic and ferroelectric behavior at room temperature, which provide potential applications for switchable and memory devices.

  4. Origin of p-type conductivity of Sb-doped ZnO nanorods and the local structure around Sb ions

    Energy Technology Data Exchange (ETDEWEB)

    Liang, J. K.; Su, H. L., E-mail: suhlnju@hotmail.com, E-mail: ycwu@hfut.edu.cn, E-mail: jcahuang@mail.ncku.edu.tw; Wu, Y. C., E-mail: suhlnju@hotmail.com, E-mail: ycwu@hfut.edu.cn, E-mail: jcahuang@mail.ncku.edu.tw [School of Materials Science and Engineering and Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices, Hefei University of Technology, Hefei 230009, Anhui (China); Chuang, P. Y.; Kuo, C. L.; Huang, S. Y. [Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (China); Chan, T. S. [National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (China); Huang, J. C. A., E-mail: suhlnju@hotmail.com, E-mail: ycwu@hfut.edu.cn, E-mail: jcahuang@mail.ncku.edu.tw [Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center and Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 106, Taiwan (China)

    2015-05-25

    To probe the origin of p-type conductivity in Sb-doped ZnO, a careful and detailed synchrotron radiation study was performed. The extended X-ray absorption fine structure and X-ray photoelectron spectroscopy investigations provided the evidence for the formation of the complex defects comprising substitution Sb ions at Zn sites (Sb{sub Zn}) and Zn vacancies within the Sb-doped ZnO lattice. Such complex defects result in the increases of Sb-O coordination number and the Sb valence and thereby lead to the p-type conductivity of Sb-doped ZnO. The back-gate field-effect-transistors based on single nanorod of Sb-doped ZnO were constructed, and the stable p-type conduction behavior was confirmed.

  5. Efros-Shklovskii type variable range hopping conduction and magnetoresistance in p-type CuGa3Te5

    Science.gov (United States)

    Wasim, S. M.; Essaleh, L.; Marín, G.; Rincón, C.; Amhil, S.; Galibert, J.

    2017-07-01

    Variable range hopping conduction of Efros and Shklovskii type when a Coulomb gap appears at the Fermi level due to repulsive interaction of the holes, is observed in two different temperature regions in the ordered defect compound CuGa3Te5. Since this type of electrical conduction appears over a very wide temperature range between 4 and 150 K, not reported before in elemental II-VI, and I-III-VI2 compound semiconductors, three different methods were employed to analyze the data to confirm this behavior. This is also supported from the study of the variation of impurity band hole mobility with temperature. Other hopping parameters are estimated. The logarithmic variation of the positive magnetoresistance at different temperatures in the two regions varies as B2 and B1/5 above and below the critical field Bc, that separates the low and high magnetic field regions. This is in complete agreement with the theory of Efros and Shklovskii. The temperature dependence of the corresponding slope as T- 3/2 and T- 3/5 is also consistent with the proposed models.

  6. The low resistive and transparent Al-doped SnO{sub 2} films: p-type conductivity, nanostructures and photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Benouis, C.E. [Department of Material Technology, Physics Faculty, USTOMB University, BP1505 Oran (Algeria); Benhaliliba, M., E-mail: mbenhaliliba@gmail.com [Department of Material Technology, Physics Faculty, USTOMB University, BP1505 Oran (Algeria); Mouffak, Z. [Department of Electrical and Computer Engineering California State University, Fresno, CA (United States); Avila-Garcia, A. [Cinvestav-IPN, Dept. Ingeniería Eléctrica-SEES, Apdo. Postal 14-740, 07000 México, D.F. (Mexico); Tiburcio-Silver, A. [ITT-DIE, Apdo, Postal 20, Metepec 3, 52176 Estado de Mexico (Mexico); Ortega Lopez, M.; Romano Trujillo, R. [Centro de Investigación en Dispositivos Semiconductores, Instituto de Ciencias-BUAP, 14 Sur y Av. San Claudio, C.U. Puebla, Pue. (Mexico); Ocak, Y.S. [Dicle University, Education Faculty, Science Department, 21280 Diyarbakir (Turkey)

    2014-08-01

    Highlights: • Low resistive and high transparency Al doped SnO{sub 2} films. • Films are deposited onto ITO substrate by spray pyrolysis. • Nanostructured films are revealed. • p-Type conductivity is exhibited. • Photoluminescence of films is studied. - Abstract: In this work, we study the crystalline structure, surface morphology, transmittance, optical bandgap and n/p type inversion of tin oxide (SnO{sub 2}). The Nanostructured films of Al-doped SnO{sub 2} were successfully produced onto ITO-coated glass substrates via the spray pyrolysis method at a deposition temperature of 300 °C. A (1 0 1) and (2 1 1)-oriented tetragonal crystal structure was confirmed by X-ray patterns; and grain sizes varied within the range 8−42 nm. The films were polycrystalline, showing a high transparency in the visible (VIS) and infrared (IR) spectra. The optical bandgap was estimated to be around 3.4 eV. The atomic force microscopy (AFM) analysis showed the nanostructures consisting of nanotips, nanopatches, nanopits and nanobubbles. The samples exhibited high conductivity that ranged from 0.55 to 10{sup 4} (S/cm) at ambient and showed an inversion from n to p-type as well as a degenerate semiconductor characters with a bulk concentration reaching 1.7 x 10{sup 19} cm{sup −3}. The photoluminescence measurements reveal the detection of violet, green and yellow emissions.

  7. Conduction mechanisms in p-type Pb{sub 1-x}Eu{sub x}Te alloys in the insulator regime

    Energy Technology Data Exchange (ETDEWEB)

    Peres, M. L.; Rubinger, R. M.; Ribeiro, L. H.; Rubinger, C. P. L. [Departamento de Fisica e Quimica, Instituto de Ciencias Exatas, Universidade Federal de Itajuba, Itajuba, PB 50, MG CEP 37500-903 (Brazil); Ribeiro, G. M. [Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, PB 702, MG CEP 30123-970 (Brazil); Chitta, V. A. [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, PB 66318, SP CEP 05315-970 (Brazil); Rappl, P. H. O.; Abramof, E. [Laboratorio Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, PB 515, SP CEP 12201-970 (Brazil)

    2012-06-15

    Electrical resistivity measurements were performed on p-type Pb{sub 1-x}Eu{sub x}Te films with Eu content x = 4%, 5%, 6%, 8%, and 9%. The well-known metal-insulator transition that occurs around 5% at room temperature due to the introduction of Eu is observed, and we used the differential activation energy method to study the conduction mechanisms present in these samples. In the insulator regime (x > 6%), we found that band conduction is the dominating conduction mechanism for high temperatures with carriers excitation between the valence band and the 4f levels originated from the Eu atoms. We also verified that mix conduction dominates the low temperatures region. Samples with x = 4% and 5% present a temperature dependent metal insulator transition and we found that this dependence can be related to the relation between the thermal energy k{sub B}T and the activation energy {Delta}{epsilon}{sub a}. The physical description obtained through the activation energy analysis gives a new insight about the conduction mechanisms in insulating p-type Pb{sub 1-x}Eu{sub x}Te films and also shed some light over the influence of the 4f levels on the transport process in the insulator region.

  8. Enhanced p-type conductivity and band gap narrowing in heavily Al doped NiO thin films deposited by RF magnetron sputtering.

    Science.gov (United States)

    Nandy, S; Maiti, U N; Ghosh, C K; Chattopadhyay, K K

    2009-03-18

    Stoichiometric NiO, a Mott-Hubbard insulator at room temperature, shows p-type electrical conduction due to the introduction of Ni(2+) vacancies (V(Ni)('')) and self-doping of Ni(3+) ions in the presence of excess oxygen. The electrical conductivity of this important material is low and not sufficient for active device fabrication. Al doped NiO thin films were synthesized by radio frequency (RF) magnetron sputtering on glass substrates at a substrate temperature of 250 °C in an oxygen + argon atmosphere in order to enhance the p-type electrical conductivity. X-ray diffraction studies confirmed the correct phase formation and also oriented growth of NiO thin films. Al doping was confirmed by x-ray photoelectron spectroscopic studies. The structural, electrical and optical properties of the films were investigated as a function of Al doping (0-4 wt%) in the target. The room temperature electrical conductivity increased from 0.01-0.32 S cm (-1) for 0-4% Al doping. With increasing Al doping, above the Mott critical carrier density, energy band gap shrinkage was observed. This was explained by the shift of the band edges due to the existence of exchange and correlation energies amongst the electron-electron and hole-hole systems and also by the interaction between the impurity quasi-particle system.

  9. Lead free CH3NH3SnI3 perovskite thin-film with p-type semiconducting nature and metal-like conductivity

    OpenAIRE

    2016-01-01

    Lead free CH3NH3SnI3 perovskite thin film was prepared by low temperature solution processing and characterized using current sensing atomic force microscopy (CS-AFM). Analysis of electrical, optical, and optoelectrical properties reveals unique p-type semiconducting nature and metal like conductivity of this material. CH3NH3SnI3 film also showed a strong absorption in visible and near infrared spectrum with absorption onset of 1.3 eV. X-ray Diffraction analysis and scanning electron microsco...

  10. Chemical Bath Deposition of p-Type Transparent, Highly Conducting (CuS)x:(ZnS)1-x Nanocomposite Thin Films and Fabrication of Si Heterojunction Solar Cells.

    Science.gov (United States)

    Xu, Xiaojie; Bullock, James; Schelhas, Laura T; Stutz, Elias Z; Fonseca, Jose J; Hettick, Mark; Pool, Vanessa L; Tai, Kong Fai; Toney, Michael F; Fang, Xiaosheng; Javey, Ali; Wong, Lydia Helena; Ager, Joel W

    2016-03-09

    P-type transparent conducting films of nanocrystalline (CuS)x:(ZnS)1-x were synthesized by facile and low-cost chemical bath deposition. Wide angle X-ray scattering (WAXS) and high resolution transmission electron microscopy (HRTEM) were used to evaluate the nanocomposite structure, which consists of sub-5 nm crystallites of sphalerite ZnS and covellite CuS. Film transparency can be controlled by tuning the size of the nanocrystallites, which is achieved by adjusting the concentration of the complexing agent during growth; optimal films have optical transmission above 70% in the visible range of the spectrum. The hole conductivity increases with the fraction of the covellite phase and can be as high as 1000 S cm(-1), which is higher than most reported p-type transparent materials and approaches that of n-type transparent materials such as indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) synthesized at a similar temperature. Heterojunction p-(CuS)x:(ZnS)1-x/n-Si solar cells were fabricated with the nanocomposite film serving as a hole-selective contact. Under 1 sun illumination, an open circuit voltage of 535 mV was observed. This value compares favorably to other emerging heterojunction Si solar cells which use a low temperature process to fabricate the contact, such as single-walled carbon nanotube/Si (370-530 mV) and graphene/Si (360-552 mV).

  11. Increased p-type conductivity in GaN{sub x}Sb{sub 1−x}, experimental and theoretical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Segercrantz, N., E-mail: natalie.segercrantz@aalto.fi; Makkonen, I.; Slotte, J.; Kujala, J.; Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 14100, FIN-00076 Aalto Espoo (Finland); Veal, T. D. [Department of Physics and Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool L69 7ZF (United Kingdom); Ashwin, M. J. [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2015-08-28

    The large increase in the p-type conductivity observed when nitrogen is added to GaSb has been studied using positron annihilation spectroscopy and ab initio calculations. Doppler broadening measurements have been conducted on samples of GaN{sub x}Sb{sub 1−x} layers grown by molecular beam epitaxy, and the results have been compared with calculated first-principle results corresponding to different defect structures. From the calculated data, binding energies for nitrogen-related defects have also been estimated. Based on the results, the increase in residual hole concentration is explained by an increase in the fraction of negative acceptor-type defects in the material. As the band gap decreases with increasing N concentration, the ionization levels of the defects move closer to the valence band. Ga vacancy-type defects are found to act as positron trapping defects in the material, and the ratio of Ga vacancy-type defects to Ga antisites is found to be higher than that of the p-type bulk GaSb substrate. Beside Ga vacancies, the calculated results imply that complexes of a Ga vacancy and nitrogen could be present in the material.

  12. Effect of Substitutional Pb Doping on Bipolar and Lattice Thermal Conductivity in p-Type Bi0.48Sb1.52Te3

    Directory of Open Access Journals (Sweden)

    Hyun-sik Kim

    2017-07-01

    Full Text Available Cation substitutional doping is an effective approach to modifying the electronic and thermal transports in Bi2Te3-based thermoelectric alloys. Here we present a comprehensive analysis of the electrical and thermal conductivities of polycrystalline Pb-doped p-type bulk Bi0.48Sb1.52Te3. Pb doping significantly increased the electrical conductivity up to ~2700 S/cm at x = 0.02 in Bi0.48-xPbxSb1.52Te3 due to the increase in hole carrier concentration. Even though the total thermal conductivity increased as Pb was added, due to the increased hole carrier concentration, the thermal conductivity was reduced by 14–22% if the contribution of the increased hole carrier concentration was excluded. To further understand the origin of reduction in the thermal conductivity, we first estimated the contribution of bipolar conduction to thermal conductivity from a two-parabolic band model, which is an extension of the single parabolic band model. Thereafter, the contribution of additional point defect scattering caused by Pb substitution (Pb in the cation site was analyzed using the Debye–Callaway model. We found that Pb doping significantly suppressed both the bipolar thermal conduction and lattice thermal conductivity simultaneously, while the bipolar contribution to the total thermal conductivity reduction increased at high temperatures. At Pb doping of x = 0.02, the bipolar thermal conductivity decreased by ~30% from 0.47 W/mK to 0.33 W/mK at 480 K, which accounts for 70% of the total reduction.

  13. Controlled p-type to n-type conductivity transformation in NiO thin films by ultraviolet-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Pranav; Dutta, Titas; Mal, Siddhartha; Narayan, Jagdish [Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27606 (United States)

    2012-01-01

    We report the systematic changes in structural, electrical, and optical properties of NiO thin films on c-sapphire introduced by nanosecond ultraviolet excimer laser pulses. Epitaxial nature of as deposited NiO was determined by x-ray diffraction phi scans and transmission electron microscopy (TEM) and it was established that NiO film growth takes place with twin domains on sapphire where two types of domains have 60 deg. in-plane rotation with respect to each other about the [111] growth direction. We determined that at pulsed laser energy density of 0.275 J/cm{sup 2}, NiO films exhibited conversion from p-type semiconducting to n-type conductive behavior with three orders of magnitude decrease in resistivity, while maintaining its cubic crystal structure and good epitaxial relationship. Our TEM and electron-energy-loss spectroscopy studies conclusively ruled out the presence of any Ni clustering or precipitation due to the laser treatment. The laser-induced n-type carrier transport and conductivity enhancement were shown to be reversible through subsequent thermal annealing in oxygen. This change in conductivity behavior was correlated with the nonequilibrium concentration of laser induced Ni{sup 0}-like defect states.

  14. Origin of the n -type and p -type conductivity of MoS 2 monolayers on a SiO 2 substrate

    KAUST Repository

    Dolui, Kapildeb

    2013-04-02

    Ab initio density functional theory calculations are performed to study the electronic properties of a MoS2 monolayer deposited over a SiO 2 substrate in the presence of interface impurities and defects. When MoS2 is placed on a defect-free substrate, the oxide plays an insignificant role since the conduction band top and the valence band minimum of MoS2 are located approximately in the middle of the SiO2 band gap. However, if Na impurities and O dangling bonds are introduced at the SiO2 surface, these lead to localized states, which modulate the conductivity of the MoS2 monolayer from n- to p-type. Our results show that the conductive properties of MoS2 deposited on SiO 2 are mainly determined by the detailed structure of the MoS 2/SiO2 interface, and suggest that doping the substrate can represent a viable strategy for engineering MoS2-based devices. © 2013 American Physical Society.

  15. Nanocomposite of p-type conductive polymer/functionalized graphene oxide nanosheets as novel and hybrid electrodes for highly capacitive pseudocapacitors.

    Science.gov (United States)

    Ehsani, A; Mohammad Shiri, H; Kowsari, E; Safari, R; Torabian, J; Kazemi, S

    2016-09-15

    An effective approach for increasing the life cycle of poly ortho aminophenol (POAP) as a p-type conductive polymers is combining conventional conductive polymers and nanomaterials to fabricate hybrid electrodes. In this paper, functionalized graphene oxide (FGO) has first been synthesized using a chemical approach. Hybrid POAP/FGO films have then been fabricated by POAP electropolymerization in the presence of FGO nanoparticles as active electrodes for electrochemical supercapacitors. Based on the atomic scale study results, it seems that H3PO4(-) oxygen atoms and terminal pyridine ring nitrogen atoms play a crucial role in the intramolecular charge and energy transfer in the FGO molecular systems. Theoretical studies, surface and electrochemical analyses have been used for characterization of POAP/FGO composite films. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. This work introduces new nanocomposite materials for electrochemical redox capacitors with such advantages as the ease of synthesis, high active surface area and stability in an aqueous electrolyte.

  16. Promoting oxygen vacancy formation and p-type conductivity in SrTiO3via alkali metal doping: a first principles study.

    Science.gov (United States)

    Triggiani, Leonardo; Muñoz-García, Ana B; Agostiano, Angela; Pavone, Michele

    2016-10-19

    Strontium titanate (SrTiO3, STO) is a prototypical perovskite oxide, widely exploited in many technological applications, from catalysis to energy conversion devices. In the context of solid-oxide fuel cells, STO has been recently applied as an epitaxial substrate for nano-sized layers of mixed ion-electron conductive catalysts with enhanced electrochemical performances. To extend the applications of such heterogeneous nano-cathodes in real devices, also the STO support should be active for both electron transport and oxide diffusion. To this end, we explored using first-principles calculations the strategy of doping of STO at the Sr site with sodium and potassium. These two ions fit in the perovskite structure and induce holes in the STO valence band, so as to obtain the desired p-type electronic conduction. At the same time, the doping with alkali ions also promotes the formation of oxygen vacancies in STO, a prerequisite for effective oxide diffusion. Analysis of electron density rearrangements upon defect formation allows relating the favorable vacancy formation energies to an improved electronic delocalization over the oxide sub-lattice, as observed in closely related materials (e.g. Sr2Fe1.5Mo0.5O6). Overall, our results suggest the alkali-doped STO as a new potential substrate material in nanoscale heterogeneous electrodes for solid oxide electrochemical cells.

  17. Two high-field thermodynamically stable conductivity states in photoconductive CdS, one n-type and one p-type

    Energy Technology Data Exchange (ETDEWEB)

    Böer, Karl W. [Department of Physics and Astronomy, 217 Sharp Lab, University of Delaware, Newark, Delaware 19716 (United States)

    2015-08-28

    Photoconductive CdS is known to be n-type and develops high-field domains in the range of negative differential conductivities. These domains have been extensively discussed, and when remaining attached to the electrodes have been renamed Böer domains (a broader definition suggested earlier is misleading) [K. Thiessen, Phys. Status Solidi B 248, 2775 (2011)]. They are occurring at high applied voltage in a range at which the current becomes highly non-ohmic that is conventionally described as N-shaped when the conductance decreases with increasing bias or as S-shaped when the current starts to increase again. In this paper only such cases will be discussed in which the current stays below significant Joule heating (no current channel formation), and only for stationary electrode-attached high-field domains. These are the cathode-attached domains that are maintained by field-quenching and are thermodynamically stable. Their finding is summarized in the first segment of this paper. When the applied voltage is increased, an anode-attached hyper-high-field domain develops that is stabilized by a hole blocking anode and will be analyzed in more detail below. It will be shown that they are a thermodynamically stable p-type photoconductive state of CdS. These two new states can be used to determine the carrier densities and mobilities as function of the field and the effective work function in dependence of the spectral distribution of the optical excitation. In a thin slab adjacent to a blocking cathode, the quasi-Fermi levels are spread to a precise amount and are kept there in the entire high-field region. This opens the opportunity to analyze with small modulation of the excitation the trap transition coefficients near these quasi-Fermi levels separately, without broadening interference from other signals. This has already resulted in the discovery of an unusually sharp electron quenching level when the CdS was in a p-type state with an anode adjacent domain. It is

  18. Lead free CH3NH3SnI3 perovskite thin-film with p-type semiconducting nature and metal-like conductivity

    Science.gov (United States)

    Iefanova, Anastasiia; Adhikari, Nirmal; Dubey, Ashish; Khatiwada, Devendra; Qiao, Qiquan

    2016-08-01

    Lead free CH3NH3SnI3 perovskite thin film was prepared by low temperature solution processing and characterized using current sensing atomic force microscopy (CS-AFM). Analysis of electrical, optical, and optoelectrical properties reveals unique p-type semiconducting nature and metal like conductivity of this material. CH3NH3SnI3 film also showed a strong absorption in visible and near infrared spectrum with absorption onset of 1.3 eV. X-ray Diffraction analysis and scanning electron microscopy (SEM) confirmed a structure of this compound and uniform film formation. The morphology, film uniformity, light harvesting and electrical properties strongly depend on preparation method and precursor solution. CH3NH3SnI3 films prepared based on dimethylformamide (DMF) showed higher crystallinity and light harvesting capability compared to the film based on combination of dimethyl sulfoxide (DMSO) with gamma-butyrolactone (GBL). Local photocurrent mapping analysis showed that CH3NH3SnI3 can be used as an active layer and have a potential to fabricate lead free photovoltaic devices.

  19. Lead free CH3NH3SnI3 perovskite thin-film with p-type semiconducting nature and metal-like conductivity

    Directory of Open Access Journals (Sweden)

    Anastasiia Iefanova

    2016-08-01

    Full Text Available Lead free CH3NH3SnI3 perovskite thin film was prepared by low temperature solution processing and characterized using current sensing atomic force microscopy (CS-AFM. Analysis of electrical, optical, and optoelectrical properties reveals unique p-type semiconducting nature and metal like conductivity of this material. CH3NH3SnI3 film also showed a strong absorption in visible and near infrared spectrum with absorption onset of 1.3 eV. X-ray Diffraction analysis and scanning electron microscopy (SEM confirmed a structure of this compound and uniform film formation. The morphology, film uniformity, light harvesting and electrical properties strongly depend on preparation method and precursor solution. CH3NH3SnI3 films prepared based on dimethylformamide (DMF showed higher crystallinity and light harvesting capability compared to the film based on combination of dimethyl sulfoxide (DMSO with gamma-butyrolactone (GBL. Local photocurrent mapping analysis showed that CH3NH3SnI3 can be used as an active layer and have a potential to fabricate lead free photovoltaic devices.

  20. Hopping conduction in p-type MoS{sub 2} near the critical regime of the metal-insulator transition

    Energy Technology Data Exchange (ETDEWEB)

    Park, Tae-Eon; Jang, Chaun, E-mail: cujang@kist.re.kr, E-mail: presto@kist.re.kr [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Suh, Joonki; Wu, Junqiao [Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Seo, Dongjea [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Park, Joonsuk [Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Lin, Der-Yuh [Department of Electronics Engineering, National Changhua University of Education, Changhua 50007, Taiwan (China); Huang, Ying-Sheng [Department of Electronics Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Choi, Heon-Jin [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Chang, Joonyeon, E-mail: cujang@kist.re.kr, E-mail: presto@kist.re.kr [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 305-350 (Korea, Republic of)

    2015-11-30

    We report on temperature-dependent charge and magneto transport of chemically doped MoS{sub 2}, p-type molybdenum disulfide degenerately doped with niobium (MoS{sub 2}:Nb). The temperature dependence of the electrical resistivity is characterized by a power law, ρ(T) ∼ T{sup −0.25}, which indicates that the system resides within the critical regime of the metal-insulator (M-I) transition. By applying high magnetic field (∼7 T), we observed a 20% increase in the resistivity at 2 K. The positive magnetoresistance shows that charge transport in this system is governed by the Mott-like three-dimensional variable range hopping (VRH) at low temperatures. According to relationship between magnetic-field and temperature dependencies of VRH resistivity, we extracted a characteristic localization length of 19.8 nm for MoS{sub 2}:Nb on the insulating side of the M-I transition.

  1. Structural, electrical and optical properties of p-type transparent conducting SnO{sub 2}:Al film derived from thermal diffusion of Al/SnO{sub 2}/Al multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J. [Key Laboratory of Silicate Materials Science and Engineering (Wuhan University of Technology), Ministry of Education, 122 Luoshi Road, Hongshan District, Wuhan, Hubei 430070 (China); Zhao, X.J., E-mail: opluse@whut.edu.cn [Key Laboratory of Silicate Materials Science and Engineering (Wuhan University of Technology), Ministry of Education, 122 Luoshi Road, Hongshan District, Wuhan, Hubei 430070 (China); Ni, J.M.; Tao, H.Z. [Key Laboratory of Silicate Materials Science and Engineering (Wuhan University of Technology), Ministry of Education, 122 Luoshi Road, Hongshan District, Wuhan, Hubei 430070 (China)

    2010-11-15

    Highly transparent, p-type conducting SnO{sub 2}:Al films derived from thermal diffusion of a sandwich structure Al/SnO{sub 2}/Al multilayer thin films deposited on quartz substrate have been prepared by direct current and radio-frequency magnetron sputtering using Al and SnO{sub 2} targets. The deposited films were annealed at various temperatures for different durations. The effect of thermal diffusing temperature and time on the structural, electrical and optical performances of SnO{sub 2}:Al films has been studied. X-ray diffraction results show that all p-type conducting films possessed polycrystalline SnO{sub 2} with tetragonal rutile structure. Hall-effect results indicate that 450 deg. C for 4 h were the optimum annealing parameters for p-type SnO{sub 2}:Al films, resulting in a relatively high hole concentration of 7.2 x 10{sup 18} cm{sup -3} and a low resistivity of 0.81 {Omega} cm. The transmission of the p-type SnO{sub 2}:Al films was above 80%.

  2. Effects of Concentration and Substrate Type on Structure and Conductivity of p-Type CuS Thin Films Grown by Spray Pyrolysis Deposition

    Science.gov (United States)

    Sabah, Fayroz A.; Ahmed, Naser M.; Hassan, Z.

    2016-09-01

    Copper sulphide (CuS) thin films were grown upon Ti, indium tin oxide (ITO), and glass substrates by using spray pyrolysis deposition at 200°C. The films exhibited good adhesion compared to chemical bath deposition. CuCl2·2H2O and Na2S2O3·5H2O precursors were used as Cu2+ and S2- sources, respectively. Two concentrations (i.e., 0.2 M and 0.4 M) were selected in this study. X-ray diffraction analysis reveals that the films with 0.2 M showed only the formation of a covellite CuS phase having a hexagonal crystal structure with diffraction peaks of low intensity. For 0.4 M concentration, in addition to the covellite CuS phase, chalcocite Cu2S phase having a hexagonal crystal structure also appeared with relatively higher intensity peaks for all thin films. Field-emission scanning electron microscopy observations showed the formation of small grains for 0.2 M, whereas a mixture of grains with square-like shape and nanoplates were formed for 0.4 M. Depending on the 0.2 M and 0.4 M thin films thicknesses (3.2 μm and 4 μm, respectively), the band gap energy was obtained from optical measurements to be approximately 2.64 eV for 0.2 M (pure CuS phase), which slightly decreased up to 2.56 eV for 0.4 M concentration. Hall effect measurements showed that all grown films are p-type. The 0.2 M film exhibited much lower sheet resistance (R sh = 33.96 Ω/Sq-55.70 Ω/Sq) compared to 0.4 M film (R sh = 104.33 Ω/Sq-466.6 Ω/Sq). Moreover, for both concentrations, the films deposited onto ITO substrate showed the lowest sheet resistance (R sh = 33.96 Ω/Sq-104.33 Ω/Sq).

  3. Effects of Concentration and Substrate Type on Structure and Conductivity of p-Type CuS Thin Films Grown by Spray Pyrolysis Deposition

    Science.gov (United States)

    Sabah, Fayroz A.; Ahmed, Naser M.; Hassan, Z.

    2017-01-01

    Copper sulphide (CuS) thin films were grown upon Ti, indium tin oxide (ITO), and glass substrates by using spray pyrolysis deposition at 200°C. The films exhibited good adhesion compared to chemical bath deposition. CuCl2·2H2O and Na2S2O3·5H2O precursors were used as Cu2+ and S2- sources, respectively. Two concentrations (i.e., 0.2 M and 0.4 M) were selected in this study. X-ray diffraction analysis reveals that the films with 0.2 M showed only the formation of a covellite CuS phase having a hexagonal crystal structure with diffraction peaks of low intensity. For 0.4 M concentration, in addition to the covellite CuS phase, chalcocite Cu2S phase having a hexagonal crystal structure also appeared with relatively higher intensity peaks for all thin films. Field-emission scanning electron microscopy observations showed the formation of small grains for 0.2 M, whereas a mixture of grains with square-like shape and nanoplates were formed for 0.4 M. Depending on the 0.2 M and 0.4 M thin films thicknesses (3.2 μm and 4 μm, respectively), the band gap energy was obtained from optical measurements to be approximately 2.64 eV for 0.2 M (pure CuS phase), which slightly decreased up to 2.56 eV for 0.4 M concentration. Hall effect measurements showed that all grown films are p-type. The 0.2 M film exhibited much lower sheet resistance ( R sh = 33.96 Ω/Sq-55.70 Ω/Sq) compared to 0.4 M film ( R sh = 104.33 Ω/Sq-466.6 Ω/Sq). Moreover, for both concentrations, the films deposited onto ITO substrate showed the lowest sheet resistance ( R sh = 33.96 Ω/Sq-104.33 Ω/Sq).

  4. Dipole-induced conductivity enhancement by n-type inclusion in a p-type system: α-Fe₂O₃-PEDOT:PSS nanocomposites.

    Science.gov (United States)

    Raccis, R; Wortmann, L; Ilyas, S; Schläfer, J; Mettenbörger, A; Mathur, S

    2014-08-07

    Hematite (α-Fe2O3) nanoparticles of two different shapes but of same size (ca. 40 nm) were dispersed in PEDOT:PSS matrices in various concentration ranges (0-7 wt%) to study the consequent changes in conductivity in the dark and under solar illumination conditions. Within a distinct range of concentration, a distinct increase in the conductivity was observed for both spherical and cubical particle population. We ascribed this effect to the generalized Poole-Frenkel theory of conduction in conjunction with the basic depletion width properties of heterojunctions and electrostatic dipole moments, and verified our assumptions through data fitting. A difference in conductivity between sphere- and cube-based α-Fe2O3-PEDOT:PSS nanocomposites was also observed and ascribed to the electrostatic edge effect on the nanoparticles. The dispersion of α-Fe2O3 nanocrystals was confirmed by high-resolution electron microscopy, whereas the electrical properties and modulations thereof were followed by recording current-voltage characteristics.

  5. A simple and innovative route to electrosynthesis of Eu2O3 nanoparticles and its nanocomposite with p-type conductive polymer: Characterisation and electrochemical properties.

    Science.gov (United States)

    Mohammad Shiri, H; Ehsani, A

    2016-07-01

    Conductive polymers are usually used as an electrode in redox supercapacitor. However, due to accumulation of stress on polymer during repeating charge-discharge process, the cycle life of pure conductive polymer is poor, which needs to be further improved. For this purpose, combining conventional conductive polymers active material and nanomaterials to fabricate hybrid electrode has been considered to be one of the efficient avenues. In this paper, a simple and rapid electrochemical method has been carried out to prepare Eu2O3 nanoparticles and hybrid POAP/Eu2O3 to serve as the active electrode for electrochemical supercapacitor. Structural and morphological characterisations of Eu2O3 and composite film were carried out using powder X-ray diffraction, field emission scanning electron microscopy and energy dispersion of X-rays. Their electrochemical properties were also investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The as-prepared composites had excellent properties in the specific capacitance and a coulombic efficiency of 95%. The as-prepared composites had excellent properties in the capacitance, and its specific capacitance was up to 375Fg(-1) and a coulombic efficiency of 95%. This work introduces new nanocomposite materials for electrochemical redox capacitors with advantages including ease synthesis, high active surface area and stability in an aqueous electrolyte.

  6. Conductance and Absolutely Continuous Spectrum of 1D Samples

    Science.gov (United States)

    Bruneau, L.; Jakšić, V.; Last, Y.; Pillet, C.-A.

    2016-06-01

    We characterize the absolutely continuous spectrum of the one-dimensional Schrödinger operators {h = -Δ + v} acting on {ℓ^2(mathbb{Z}_+)} in terms of the limiting behaviour of the Landauer-Büttiker and Thouless conductances of the associated finite samples. The finite sample is defined by restricting h to a finite interval {[1, L] \\cap mathbb{Z}_+} and the conductance refers to the charge current across the sample in the open quantum system obtained by attaching independent electronic reservoirs to the sample ends. Our main result is that the conductances associated to an energy interval {I} are non-vanishing in the limit {L to infty} iff {sp_ac(h) \\cap I neq emptyset}. We also discuss the relationship between this result and the Schrödinger Conjecture (Avila, J Am Math Soc 28:579-616, 2015; Bruneau et al., Commun Math Phys 319:501-513, 2013).

  7. DEPTH CONTINUOUS HYDRAULIC CONDUCTIVITY PROFILING USING AN ACTIVE SOURCE PENETROMETER

    Science.gov (United States)

    Fitzgerald, M.; Elsworth, D.

    2009-12-01

    A method is developed to recover depth-continuous hydraulic conductivity profiles of an unconsolidated saturated aquifer using an active source penetrometer, the Hydraulic Profiling Tool (HPT). The tool yields estimates of K through continuous injection of fluid in the subsurface from a small port on the probe shaft while controlled measurements of net applied fluid pressure required to maintain a specified flow rate (typically 350 mL/min) are recorded. The tool gathers these data of flow rate and measured applied pressure during halted and constant-rate penetration (typically 2cm/sec) of the probe. The analysis is developed in two parts, first to explore the interplay between advective effects controlled by penetration rate and secondly flow volume effects controlled by the targeted flow rate. These two effects are analyzed through their respective influence on the measured applied pressure response in ΔP/σv’-Q/ΔP space, which shows a linear relationship for the flow rate to applied pressure response when Q/ΔP > 1 and when Q/ΔP 1. The analysis shows that penetration rate does not significantly influence the applied pressure response at the tested penetration rates (0 ≤ U(cm/s)≤ 4). The targeted applied flow rate does however influence the applied pressure response as flow rates less than ~300 mL/min show a scattering of the data in ΔP/σv’-Q/ΔP space, where above 300 mL/min the data begins to form a linear response. A targeted flow rate of QT = 400mL/min is suggested as a suitable flow rate based on this analysis. Measurements of hydraulic conductivity are then obtained for the HPT data through the derivation of an equation based on a recast form of Darcy’s law where considerations of the flow geometry as K = (QHPT/ΔP)(δw/πΦ). K profiles obtained for the HPT system are then compared against K profiles obtained from an independent method (PSU permeameter) and yield a good correlation between the two methods.

  8. Lead free CH{sub 3}NH{sub 3}SnI{sub 3} perovskite thin-film with p-type semiconducting nature and metal-like conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Iefanova, Anastasiia; Adhikari, Nirmal; Dubey, Ashish; Khatiwada, Devendra; Qiao, Qiquan, E-mail: qiquan.qiao@sdstate.edu [South Dakota State University, Brookings, South Dakota (United States)

    2016-08-15

    Lead free CH{sub 3}NH{sub 3}SnI{sub 3} perovskite thin film was prepared by low temperature solution processing and characterized using current sensing atomic force microscopy (CS-AFM). Analysis of electrical, optical, and optoelectrical properties reveals unique p-type semiconducting nature and metal like conductivity of this material. CH{sub 3}NH{sub 3}SnI{sub 3} film also showed a strong absorption in visible and near infrared spectrum with absorption onset of 1.3 eV. X-ray Diffraction analysis and scanning electron microscopy (SEM) confirmed a structure of this compound and uniform film formation. The morphology, film uniformity, light harvesting and electrical properties strongly depend on preparation method and precursor solution. CH{sub 3}NH{sub 3}SnI{sub 3} films prepared based on dimethylformamide (DMF) showed higher crystallinity and light harvesting capability compared to the film based on combination of dimethyl sulfoxide (DMSO) with gamma-butyrolactone (GBL). Local photocurrent mapping analysis showed that CH{sub 3}NH{sub 3}SnI{sub 3} can be used as an active layer and have a potential to fabricate lead free photovoltaic devices.

  9. Piezoresistance in p-type silicon revisited

    DEFF Research Database (Denmark)

    Richter, Jacob; Pedersen, Jesper; Brandbyge, Mads;

    2008-01-01

    We calculate the shear piezocoefficient pi44 in p-type Si with a 6×6 k·p Hamiltonian model using the Boltzmann transport equation in the relaxation-time approximation. Furthermore, we fabricate and characterize p-type silicon piezoresistors embedded in a (001) silicon substrate. We find that the ...

  10. DPL Model Analysis of Non-Fourier Heat Conduction Restricted by Continuous Boundary Interface

    Institute of Scientific and Technical Information of China (English)

    Jiang Fangming; Liu Dengying

    2001-01-01

    Dual-phase lag (DPL) model is used to describe the non-Fourier heat conduction in a finite medium where the boundary at x=-0 is heated by a rectangular pulsed energy source and the other boundary is tightly contacted with another medium and satisfies the continuous boundary condition. Numerical solution of this kind of. non-Fourier heat conduction is presented in this paper. The results are compared with those predicted by the hyperbolic heat conduction (HHC) equation.

  11. Characteristics of switched reluctance motor operating in continuous and discontinuous conduction mode

    Directory of Open Access Journals (Sweden)

    Ćalasan Martin P.

    2013-01-01

    Full Text Available This paper presents mechanical characteristics of Switched Reluctance Motor (SRM when it operates in Discontinuous Conduction Mode (DCM or in Continuous Conduction Mode (CCM, i.e. when the current through the phase coils (windings flows discontinuously or continuously. Firstly, in order to maximize the output power of SRM optimization of its control parameters was performed, such that the peak and RMS values of the current do not exceed the predefined values. The optimal control parameters vs. rotation speed, as well as the corresponding characteristics of torque, power and efficiency. It is shown that with CCM the machine torque (power, at high speed, can be increased.

  12. Synthesis of Continuous Conductive PEDOT:PSS Nanofibers by Electrospinning: A Conformal Coating for Optoelectronics.

    Science.gov (United States)

    Bessaire, Bastien; Mathieu, Maillard; Salles, Vincent; Yeghoyan, Taguhi; Celle, Caroline; Simonato, Jean-Pierre; Brioude, Arnaud

    2017-01-11

    A process to synthesize continuous conducting nanofibers were developed using PEDOT:PSS as a conducting polymer and an electrospinning method. Experimental parameters were carefully explored to achieve reproducible conductive nanofibers synthesis in large quantities. In particular, relative humidity during the electrospinning process was proven to be of critical importance, as well as doping post-treatment involving glycols and alcohols. The synthesized fibers were assembled as a mat on glass substrates, forming a conductive and transparent electrode and their optoelectronic have been fully characterized. This method produces a conformable conductive and transparent coating that is well-adapted to nonplanar surfaces, having very large aspect ratio features. A demonstration of this property was made using surfaces having deep trenches and high steps, where conventional transparent conductive materials fail because of a lack of conformability.

  13. Hexagonally-arranged-nanoporous and continuous NiO films with varying electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gutiérrez, A., E-mail: a.gutierrez@uam.es [Departamento de Física Aplicada and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Domínguez-Cañizares, G. [Departamento de Física Aplicada and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Jiménez, J.A. [Centro Nacional de Investigaciones Metalúrgicas, CSIC, Avda Gregorio del Amo 8, E-28040 Madrid (Spain); Preda, I. [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex 9 (France); Díaz-Fernández, D. [Departamento de Física Aplicada and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Jiménez-Villacorta, F. [Department of Chemical Engineering, Northeastern University, 360 Huntington Ave., Boston, MA 02115 (United States); Castro, G.R. [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex 9 (France); Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz, 3, E-28049 Madrid (Spain); Chaboy, J. [Instituto de Ciencia de Materiales de Aragón, CSIC, and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Soriano, L. [Departamento de Física Aplicada and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)

    2013-07-01

    Nickel oxide (NiO) thin films have been prepared by magnetron sputtering, with different Ar/O{sub 2} ratios in the plasma, on several substrates, including hexagonally arranged nanoporous anodic alumina membranes (AAM). The obtained films exhibit columnar growth, which makes it possible to preserve the hexagonal order of the AAM substrates in the NiO thin films. X ray diffraction patterns show a polycrystalline structure with a crystallographic texture that depends on the plasma composition. Additionally, the NiO lattice parameter increases with the oxygen content of the plasma. The presence of oxygen during deposition is responsible for these structural changes, as well as for an oxygen enrichment in the NiO films, which leads to changes in their electrical properties. The electrical resistivity of the films decreases with the oxygen content of the plasma, which suggests p-type conductivity due to oxygen enrichment in the NiO lattice. Indeed, an analysis of the EXAFS oscillations at the Ni–K edge confirms the lattice expansion and a decrease of the Ni–Ni coordination number when the oxygen content of the plasma increases, which points towards an increasing presence of Ni vacancies for larger values of the O{sub 2}/Ar ratio.

  14. Evolution of plant P-type ATPases

    Directory of Open Access Journals (Sweden)

    Christian N.S. Pedersen

    2012-02-01

    Full Text Available Five organisms having completely sequenced genomes and belonging to all major branches of green plants (Viridiplantae were analyzed with respect to their content of P-type ATPases encoding genes. These were the chlorophytes Ostreococcus tauria and Chlamydomonas reinhardtii, and the streptophytes Physcomitrella patens (a moss, Selaginella moellendorffii (a primitive vascular plant, and Arabidopsis thaliana (a model flowering plant. Each organism contained sequences for all five subfamilies of P-type ATPases. Our analysis demonstrates when specific subgroups of P-type ATPases disappeared in the evolution of Angiosperms. Na/K-pump related P2C ATPases were lost with the evolution of streptophytes whereas Na+ or K+ pumping P2D ATPases and secretory pathway Ca2+-ATPases remained until mosses. An N-terminally located calmodulin binding domain in P2B ATPases can only be detected in pumps from Streptophytae, whereas, like in animals, a C-terminally localized calmodulin binding domain might be present in chlorophyte P2B Ca2+-ATPases. Chlorophyte genomes encode P3A ATPases resembling protist plasma membrane H+-ATPases and a C-terminal regulatory domain is missing. The complete inventory of P-type ATPases in the major branches of Viridiplantae is an important starting point for elucidating the evolution in plants of these important pumps.

  15. Development of a team-based framework for conducting self-assessment of Continuous Improvement

    DEFF Research Database (Denmark)

    Jørgensen, Frances; Gertsen, Frank; Boer, Harry

    2004-01-01

    The study presented in this article is based on two basic premises. First, successful continuous improvement (CI) is dependent on shop floor level involvement and participation in improvement efforts. Second, the term "self-assessment" clearly implies that those whose performance is being measure......, the study shows how these principles relate to the teams' own work processes, and a deeper understanding of their organization's strategy and objectives......., and who are involved in conducting the assessment process. Excerpts from longitudinal case studies in a single Danish manufacturing organization demonstrate how teams involved in the process of conducting self-assessment of CI developed a better understanding of the basic principles of CI. Furthermore...

  16. Development of a team-based framework for conducting self-assessment of Continuous Improvement

    DEFF Research Database (Denmark)

    Jørgensen, Frances; Gertsen, Frank; Boer, Harry

    2004-01-01

    The study presented in this article is based on two basic premises. First, successful continuous improvement (CI) is dependent on shop floor level involvement and participation in improvement efforts. Second, the term "self-assessment" clearly implies that those whose performance is being measure......, the study shows how these principles relate to the teams' own work processes, and a deeper understanding of their organization's strategy and objectives......., and who are involved in conducting the assessment process. Excerpts from longitudinal case studies in a single Danish manufacturing organization demonstrate how teams involved in the process of conducting self-assessment of CI developed a better understanding of the basic principles of CI. Furthermore...

  17. Characterization and Evaluation of 600 V Range Devices for Active Power Factor Correction in Boundary and Continuous Conduction Modes

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2015-01-01

    Traditional characterization of semiconductors switching dynamics is performed based on clamped inductive load measurements using the double pulse tester (DPT) configuration. This approach is valid for converters operating in continuous conduction mode (CCM), however in boundary conduction mode (...

  18. Characterization and Evaluation of 600 V Range Devices for Active Power Factor Correction in Boundary and Continuous Conduction Modes

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2015-01-01

    Traditional characterization of semiconductors switching dynamics is performed based on clamped inductive load measurements using the double pulse tester (DPT) configuration. This approach is valid for converters operating in continuous conduction mode (CCM), however in boundary conduction mode...

  19. Conduction Disorders in Continuous Versus Interrupted Suturing Technique in Ventricular Septal Defect Surgical Repair

    Directory of Open Access Journals (Sweden)

    Gholampour-Dehaki

    2016-01-01

    Full Text Available Background Ventricular septal defects (VSD is one of the most frequent congenital cardiac malformations and cardiac conduction disorders are still one of the serious postoperative complications in this surgery. Objectives This study aimed to compare the incidence of conduction disorders with the use of continuous compared to interrupted suturing techniques in VSD surgical repair. Patients and Methods Previously recorded data of 231 patients who underwent surgical closure of VSD between January 2009 and January 2012 at the Rajaie cardiovascular medical and research center were retrospectively reviewed. VSD surgical repair was performed using continues suturing technique in group A patients (n = 163, 70.6% and interrupted suturing technique in group B patients (n = 68, 29.4%. Results The most common concomitant congenital anomaly was Tetralogy of Fallot (27.3%. Twenty-four (10.4% patients had intraoperative cardiac arrhythmia, including 19 (8.2% transient and 5 (2.2 % permanent arrhythmia. During their ICU stay, ventricular arrhythmia and complete heart block were observed in 34 (14.7% and 5 patients (2.2%, respectively. At the time of the last follow-up, incomplete right bundle branch block (RBBB, complete RBBB, RBBB with left anterior hemi-block, and complete heart block were identified in 84 (36.4%, 42 (18.2%, 29 (12.6%, and 5 patients (2.2%, respectively. The results revealed that group A patients were most likely to have had cardiac arrhythmias during their ICU stay and at the time of last follow-up (P < 0.001, while the intraoperative incidence of cardiac arrhythmia during surgery was not statistically significant between the two groups (P = 0.06. Conclusions In the absence of any statistical differences in the other risk factors between the two groups, the difference in the incidence of conduction disorders can be attributed to the type of suturing used during the procedure.

  20. General Boundary-Value Problems for the Heat Conduction Equation with Piecewise-Continuous Coefficients

    Science.gov (United States)

    Tatsii, R. M.; Pazen, O. Yu.

    2016-03-01

    A constructive scheme for the construction of a solution of a mixed problem for the heat conduction equation with piecewise-continuous coefficients coordinate-dependent in the final interval is suggested and validated in the present work. The boundary conditions are assumed to be most general. The scheme is based on: the reduction method, the concept of quasi-derivatives, the currently accepted theory of the systems of linear differential equations, the Fourier method, and the modified method of eigenfunctions. The method based on this scheme should be related to direct exact methods of solving mixed problems that do not employ the procedures of constructing Green's functions or integral transformations. Here the theorem of eigenfunction expansion is adapted for the case of coefficients that have discontinuity points of the 1st kind. The results obtained can be used, for example, in investigating the process of heat transfer in a multilayer slab under conditions of ideal thermal contact between the layers. A particular case of piecewise-continuous coefficients is considered. A numerical example of calculation of a temperature field in a real four-layer building slab under boundary conditions of the 3rd kind (conditions of convective heat transfer) that model the phenomenon of fire near one of the external surfaces is given.

  1. Power Factor Correction and THD Minimization by Interleaved Boost Converter in Continuous Conduction Mode

    Directory of Open Access Journals (Sweden)

    Saubhik Maulik

    2014-02-01

    Full Text Available The electrical energy available in the utility grid is not suitable for direct use in many applications. In particular, applications requiring DC source must involve an interface device between the AC power line and the load requiring the DC voltage. Conventional AC/DC conversion involves diode rectifiers with large capacitor to reduce DC voltage ripple. The filter capacitor reduces the ripple present in the output voltage but draws non-sinusoidal line current which reduces the power factor. So power factor correction (PFC techniques are gaining increasing attention. The most popular topology for active PFC is boost converter as it draws continuous input current. This input current can be manipulated by average current mode control technique. But there are ripple in the input current due to inductor of boost converter which can be minimized by using two phase interleaved boost converter. Here average current mode controlled interleaved boost converter in continuous conduction mode using PI controller, is represented which provides high power factor and low THD.

  2. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    Science.gov (United States)

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-07

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future.

  3. Effects of calculation approaches for thermal conductivity on the simulation accuracy of billet continuous casting

    Institute of Scientific and Technical Information of China (English)

    Zun Peng; Yan-ping Bao; Ya-nan Chen; Li-kang Yang; Cao Xie; Feng Zhang

    2014-01-01

    An unsteady, two-dimensional, explicitly solved finite difference heat transfer model of a billet caster was presented to clarify the influence of the thermal conductivity of steel on model accuracy. Different approaches were utilized for calculating the thermal conductivity of solid, mushy and liquid steels. Model results predicted by these approaches were compared, and the advantages of advocated approaches were discussed. It is found that the approach for calculating the thermal conductivity of solid steel notably influences model predictions. Convection effects of liquid steel should be considered properly while calculating the thermal conductivity of mushy steel. Different values of the effective thermal conductivity of liquid steel adopted could partly be explained by the fact that different models adopted dissimilar ap-proaches for calculating the thermal conductivity of solid and mushy steels.

  4. Continuous glucose monitoring microsensor with a nanoscale conducting matrix and redox mediator

    Science.gov (United States)

    Pesantez, Daniel

    The major limiting factor in kidney clinical transplantation is the shortage of transplantable organs. The current inability to distinguish viability from non-viability on a prospective basis represents a major obstacle in any attempt to expand organ donor criteria. Consequently, a way to measure and monitor a relevant analyte to assess kidney viability is needed. For the first time, the initial development and characterization of a metabolic microsensor to assess kidney viability is presented. The rate of glucose consumption appears to serve as an indicator of kidney metabolism that may distinguish reversible from irreversible kidney damage. The proposed MetaSense (Metabolic Sensor) microdevice would replace periodic laboratory diagnosis tests with a continuous monitor that provides real-time data on organ viability. Amperometry, a technique that correlates an electrical signal with analyte concentration, is used as a method to detect glucose concentrations. A novel two-electrode electrochemical sensing cell design is presented. It uses a modified metallic working electrode (WE) and a bare metallic reference electrode (RE) that acts as a pseudo-reference/counter electrode as well. The proposed microsensor has the potential to be used as a minimally invasive sensor for its reduced number of probes and very small dimensions achieved by micromachining and lithography. In order to improve selectivity of the microdevice, two electron transfer mechanisms or generations were explored. A first generation microsensor uses molecular oxygen as the electron acceptor in the enzymatic reaction and oxidizes hydrogen peroxide (H2O2) to get the electrical signal. The microsensor's modified WE with conductive polymer polypyrrole (PPy) and corresponding enzyme glucose oxidase (GOx) immobilized into its matrix, constitutes the electrochemical detection mechanism. Photoluminescence spectroscopic analysis confirmed and quantified enzyme immobilized concentrations within the matrix. In

  5. Continuous sheathless microparticle and cell patterning using CL-SSAWs (conductive liquid-based standing surface acoustic waves)

    Science.gov (United States)

    Nam, Jeonghun; Kim, Jae Young; Lim, Chae Seung

    2017-01-01

    We present continuous, sheathless microparticle patterning using conductive liquid (CL)-based standing surface acoustic waves (SSAWs). Conventional metal electrodes patterned on a piezoelectric substrate were replaced with electrode channels filled with a CL. The device performance was evaluated with 5-μm fluorescent polystyrene particles at different flow rate and via phase shifting. In addition, our device was further applied to continuous concentration of malaria parasites at the sidewalls of the fluidic channel.

  6. Continuous sheathless microparticle and cell patterning using CL-SSAWs (conductive liquid-based standing surface acoustic waves

    Directory of Open Access Journals (Sweden)

    Jeonghun Nam

    2017-01-01

    Full Text Available We present continuous, sheathless microparticle patterning using conductive liquid (CL-based standing surface acoustic waves (SSAWs. Conventional metal electrodes patterned on a piezoelectric substrate were replaced with electrode channels filled with a CL. The device performance was evaluated with 5-μm fluorescent polystyrene particles at different flow rate and via phase shifting. In addition, our device was further applied to continuous concentration of malaria parasites at the sidewalls of the fluidic channel.

  7. Non-destructive label-free continuous monitoring of in vitro chondrogenesis via electrical conductivity and its anisotropy.

    Science.gov (United States)

    Oh, Tong In; Kim, Changhwan; Karki, Bishal; Son, Youngsook; Lee, EunAh; Woo, Eung Je

    2015-02-01

    Non-destructive label-free continuous monitoring of in vitro tissue culture is an unmet demand in tissue engineering. Noting that different compositions of cartilage lead to different electrical tissue properties, we propose a new method to measure the electrical conductivity and its anisotropy during in vitro chondrogenesis. We used a conductivity tensor probe with 17 electrodes and a bio-impedance spectroscopy (BIS) device to measure the conductivity values and the anisotropy ratios at the bottom and top surfaces of the tissue samples during the culture period of 6 weeks. Clearly distinguishing glycosaminoglycans (GAGs), collagen, and also various mixtures of them, the measured conductivity value and the estimated tissue anisotropy provide diagnostic information of the depth-dependent tissue structure and compositions. Continuously monitoring the individual tissue during the entire chondrogenesis process without any adverse effect, the proposed method may significantly increase the productivity of cartilage tissue engineering.

  8. Identification of Small Inhomogeneities of Extreme Conductivity by Boundary Measurements: A Continuous Dependence Result.

    Science.gov (United States)

    1987-12-01

    location of the inhomogeneities and their geometry. Secondly we use this repr""’ntatien formula to prove a Lipschitz c,,t ,,¢us dcpcoidence estimate...A. Pericak-Spector, S. J. Spector, Nonuniqueness for a Hyperbolic System: Cavitation in Nonlinear Elastodynamics 306 E. G. Kalnins, W. Miller, Jr., q...Saturated Porous Media: Lipschitz Continuity of the Interface 336 B. J. Lucier, Regularity Through Approximation for Scalar Conservation Laws 337 B

  9. Convergence of valence bands for high thermoelectric performance for p-type InN

    Science.gov (United States)

    Li, Hai-Zhu; Li, Ruo-Ping; Liu, Jun-Hui; Huang, Ming-Ju

    2015-12-01

    Band engineering to converge the bands to achieve high valley degeneracy is one of effective approaches for designing ideal thermoelectric materials. Convergence of many valleys in the valence band may lead to a high Seebeck coefficient, and induce promising thermoelectric performance of p-type InN. In the current work, we have systematically investigated the electronic structure and thermoelectric performance of wurtzite InN by using the density functional theory combined with semiclassical Boltzmann transport theory. Form the results, it can be found that intrinsic InN has a large Seebeck coefficient (254 μV/K) and the largest value of ZeT is 0.77. The transport properties of p-type InN are better than that of n-type one at the optimum carrier concentration, which mainly due to the large Seebeck coefficient for p-type InN, although the electrical conductivity of n-type InN is larger than that of p-type one. We found that the larger Seebeck coefficient for p-type InN may originate from the large valley degeneracy in the valence band. Moreover, the low minimum lattice thermal conductivity for InN is one key factor to become a good thermoelectric material. Therefore, p-type InN could be a potential material for further applications in the thermoelectric area.

  10. P type porous silicon resistivity and carrier transport

    Energy Technology Data Exchange (ETDEWEB)

    Ménard, S., E-mail: samuel.menard@st.com [STMicroelectronics, 10, rue Thalès de Milet, 37071 Tours Cedex 2 (France); Fèvre, A. [STMicroelectronics, 10, rue Thalès de Milet, 37071 Tours Cedex 2 (France); Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, Tours (France); Billoué, J.; Gautier, G. [Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, Tours (France)

    2015-09-14

    The resistivity of p type porous silicon (PS) is reported on a wide range of PS physical properties. Al/PS/Si/Al structures were used and a rigorous experimental protocol was followed. The PS porosity (P{sub %}) was found to be the major contributor to the PS resistivity (ρ{sub PS}). ρ{sub PS} increases exponentially with P{sub %}. Values of ρ{sub PS} as high as 1 × 10{sup 9} Ω cm at room temperature were obtained once P{sub %} exceeds 60%. ρ{sub PS} was found to be thermally activated, in particular, when the temperature increases from 30 to 200 °C, a decrease of three decades is observed on ρ{sub PS}. Based on these results, it was also possible to deduce the carrier transport mechanisms in PS. For P{sub %} lower than 45%, the conduction occurs through band tails and deep levels in the tissue surrounding the crystallites. When P{sub %} overpasses 45%, electrons at energy levels close to the Fermi level allow a hopping conduction from crystallite to crystallite to appear. This study confirms the potential of PS as an insulating material for applications such as power electronic devices.

  11. Strength and conductivity of unidirectional copper composites reinforced by continuous SiC fibers

    Science.gov (United States)

    Kimmig, S.; Allen, I.; You, J. H.

    2013-09-01

    A SiC long fiber-reinforced copper composite offers a beneficial combination of high strength and high thermal conductivity at elevated temperatures. Both properties make the composite a promising material for the heat sink of high-heat-flux components. In this work, we developed a novel Cu/SiCf composite using the Sigma fiber. Based on HIP technique, a metallurgical process was established for fabricating high quality specimens using a TiC interface coating. Extensive tensile tests were conducted on the unidirectionally reinforced composite at 20 °C and 300 °C for a wide range of fiber volume fraction (Vf). In this paper, a large amount of test data is presented. The transversal thermal conductivity varies from 260 to 130 W/mK at 500 °C as Vf is increased from 13% to 37%. The tensile strength reached up to 1246 MPa at 20 °C for Vf = 37.6%, where the fracture strain was limited to 0.8%. The data of both elastic modulus and ultimate strength exhibited a good agreement with the rule-of-mixture predictions indicating a high quality of the materials. The strength of the composite with the Sigma fibers turned out to be superior to those of the SCS6 fibers at 300 °C, although the SCS6 fiber actually has a higher strength than the Sigma fiber. The fractographic pictures of tension test and fiber push-out test manifested a sufficient interfacial bonding. Unidirectional copper composite reinforced by long SiC fibers was fabricated using the Sigma SM1140+ fiber for a wide range of fiber volume fraction from 14% to 40%. Extensive tensile tests were carried out at RT and 300 °C. The data of ultimate strength as well as elastic modulus exhibited a good agreement with the rule-of-mixture predictions indicating a high quality of the materials. In terms of the tensile strength, the Cu/Sigma composite turned out to be superior to the previous Cu/SCS6 composite at 300 °C, while comparable at RT, although the SCS6 fiber has a higher strength than the Sigma fiber. Such a

  12. Quasi-adiabatic Continuation for Disordered Systems: Applications to Correlations, Lieb-Schultz-Mattis, and Hall Conductance

    CERN Document Server

    Hastings, M B

    2010-01-01

    We present a possible definition of a mobility gap for a many-body quantum system, in analogy to definitions of dynamical localization for single particle systems. Using this definition, we construct "corrected" quasi-adiabatic continuation operators. Under an appropriate definition of a unique ground state, we show how to introduce virtual fluxes. Armed with these results, we can directly carry over previous results in the case of a spectral gap. We present a proof of decay of correlation functions and we present a proof of Hall conductance quantization under very mild density-of-states assumptions defined later. We also generalize these definitions to the case of a "bulk mobility gap", in the case of a system with boundaries, and present a proof of Hall conductance quantization on an annulus under appropriate assumptions. Further, we present a new "optimized" quasi-adiabatic continuation operator which simplifies previous estimates and tightens bounds in certain cases. This is presented in an appendix which...

  13. Linear Modeling of the Three-Phase Diode Front-Ends with Reduced Capacitance Considering the Continuous Conduction Mode

    DEFF Research Database (Denmark)

    Máthé, Lászlo; Yang, Feng; Wang, Dong

    2016-01-01

    Reducing the DC-link capacitance considerably is a new trend in many applications, such as: motor drives, electrolysers etc.. A straight forward method for modelling the diode front-end is to build a non-linear diode based model. This non-linear model gives difficulties when the controllers...... for the entire drive systems have to be designed. A linearization and simplification to single phase model can be performed; however, when inductance is present at the grid side its performance is not satisfactory. The problem is mainly caused by neglecting the continuous conduction mode of the rectifier...... in the simplified model. This article proposes a simplified linear model where the continuous conduction mode is also considered. The DC-link voltage and current waveforms obtained through the proposed simplified model matches very well the waveforms obtained with the three phase diode based model and also...

  14. Simulation and Experimental Study on the Steady Conduction Solution for Continuous Rheo-Casting for A356 Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Duc, Do Minh; Hai, Nguyen Hong; Quang, Pham [Hanoi University of Science and Technology (HUST), Hanoi (Viet Nam)

    2017-03-15

    Computational fluid dynamic modeling of a continuous rheo-casting technology was conducted, consistent with the manufacturing of 3 {sup mm-thin} plates made of aluminum alloy A356. The A numerical simulation on of the stabilizing time of the material crystallization was carried out using the ANSYS FLUENT code. Solidification and melting models were simulated with heat transfer and solid-liquid phase transformation involving the latent heat of crystallization were simulated. The calculated temperature distribution and the evolution of cooling rate through the material were examined and used to clarify their influence on microstructure, and further investigated with hardness testing. The thickness of the mushy zone was determined for the steady conduction solution of the continuous rheo-casting process.

  15. Linear Modeling of the Three-Phase Diode Front-Ends with Reduced Capacitance Considering the Continuous Conduction Mode

    DEFF Research Database (Denmark)

    Máthé, Lászlo; Yang, Feng; Wang, Dong

    2016-01-01

    Reducing the DC-link capacitance considerably is a new trend in many applications, such as: motor drives, electrolysers etc.. A straight forward method for modelling the diode front-end is to build a non-linear diode based model. This non-linear model gives difficulties when the controllers...... for the entire drive systems have to be designed. A linearization and simplification to single phase model can be performed; however, when inductance is present at the grid side its performance is not satisfactory. The problem is mainly caused by neglecting the continuous conduction mode of the rectifier...... in the simplified model. This article proposes a simplified linear model where the continuous conduction mode is also considered. The DC-link voltage and current waveforms obtained through the proposed simplified model matches very well the waveforms obtained with the three phase diode based model and also...

  16. Electronic processes in uniaxially stressed p-type germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dubon, Jr., Oscar Danilo [Univ. of California, Berkeley, CA (United States)

    1996-02-01

    Effect of uniaxial stress on acceptor-related electronic processes in Ge single crystals doped with Ga, Be, and Cu were studied by Hall and photo-Hall effect measurements in conjunction with infrared spectroscopy. Stress dependence of hole lifetime in p-type Ge single crystals is used as a test for competing models of non-radiative capture of holes by acceptors. Photo-Hall effect shows that hole lifetime in Ga- and Be-doped Ge increases by over one order of magnitude with uniaxial stress at liq. He temps. Photo-Hall of Ge:Be shows a stress-induced change in the temperature dependence of hole lifetime. This is consistent with observed increase of responsivity of Ge:Ga detectors with uniaxial stress. Electronic properties of Ge:Cu are shown to change dramatically with uniaxial stress; the results provide a first explanation for the performance of uniaxially stressed, Cu-diffused Ge:Ga detectors which display a high conductivity in absence of photon signal and therefore have poor sensitivity.

  17. Continuous Carbon Nanotube-Ultrathin Graphite Hybrid Foams for Increased Thermal Conductivity and Suppressed Subcooling in Composite Phase Change Materials.

    Science.gov (United States)

    Kholmanov, Iskandar; Kim, Jaehyun; Ou, Eric; Ruoff, Rodney S; Shi, Li

    2015-12-22

    Continuous ultrathin graphite foams (UGFs) have been actively researched recently to obtain composite materials with increased thermal conductivities. However, the large pore size of these graphitic foams has resulted in large thermal resistance values for heat conduction from inside the pore to the high thermal conductivity graphitic struts. Here, we demonstrate that the effective thermal conductivity of these UGF composites can be increased further by growing long CNT networks directly from the graphite struts of UGFs into the pore space. When erythritol, a phase change material for thermal energy storage, is used to fill the pores of UGF-CNT hybrids, the thermal conductivity of the UGF-CNT/erythritol composite was found to increase by as much as a factor of 1.8 compared to that of a UGF/erythritol composite, whereas breaking the UGF-CNT bonding in the hybrid composite resulted in a drop in the effective room-temperature thermal conductivity from about 4.1 ± 0.3 W m(-1) K(-1) to about 2.9 ± 0.2 W m(-1) K(-1) for the same UGF and CNT loadings of about 1.8 and 0.8 wt %, respectively. Moreover, we discovered that the hybrid structure strongly suppresses subcooling of erythritol due to the heterogeneous nucleation of erythritol at interfaces with the graphitic structures.

  18. Electrically continuous graphene from single crystal copper verified by terahertz conductance spectroscopy and micro four-point probe.

    Science.gov (United States)

    Buron, Jonas D; Pizzocchero, Filippo; Jessen, Bjarke S; Booth, Timothy J; Nielsen, Peter F; Hansen, Ole; Hilke, Michael; Whiteway, Eric; Jepsen, Peter U; Bøggild, Peter; Petersen, Dirch H

    2014-11-12

    The electrical performance of graphene synthesized by chemical vapor deposition and transferred to insulating surfaces may be compromised by extended defects, including for instance grain boundaries, cracks, wrinkles, and tears. In this study, we experimentally investigate and compare the nano- and microscale electrical continuity of single layer graphene grown on centimeter-sized single crystal copper with that of previously studied graphene films, grown on commercially available copper foil, after transfer to SiO2 surfaces. The electrical continuity of the graphene films is analyzed using two noninvasive conductance characterization methods: ultrabroadband terahertz time-domain spectroscopy and micro four-point probe, which probe the electrical properties of the graphene film on different length scales, 100 nm and 10 μm, respectively. Ultrabroadband terahertz time-domain spectroscopy allows for measurement of the complex conductance response in the frequency range 1-15 terahertz, covering the entire intraband conductance spectrum, and reveals that the conductance response for the graphene grown on single crystalline copper intimately follows the Drude model for a barrier-free conductor. In contrast, the graphene grown on commercial copper foil shows a distinctly non-Drude conductance spectrum that is better described by the Drude-Smith model, which incorporates the effect of preferential carrier backscattering associated with extended, electronic barriers with a typical separation on the order of 100 nm. Micro four-point probe resistance values measured on graphene grown on single crystalline copper in two different voltage-current configurations show close agreement with the expected distributions for a continuous 2D conductor, in contrast with previous observations on graphene grown on commercial copper foil. The terahertz and micro four-point probe conductance values of the graphene grown on single crystalline copper shows a close to unity correlation, in

  19. Formation of p-type ZnO thin film through co-implantation

    Science.gov (United States)

    Chuang, Yao-Teng; Liou, Jhe-Wei; Woon, Wei-Yen

    2017-01-01

    We present a study on the formation of p-type ZnO thin film through ion implantation. Group V dopants (N, P) with different ionic radii are implanted into chemical vapor deposition grown ZnO thin film on GaN/sapphire substrates prior to thermal activation. It is found that mono-doped ZnO by N+ implantation results in n-type conductivity under thermal activation. Dual-doped ZnO film with a N:P ion implantation dose ratio of 4:1 is found to be p-type under certain thermal activation conditions. Higher p-type activation levels (1019 cm-3) under a wider thermal activation range are found for the N/P dual-doped ZnO film co-implanted by additional oxygen ions. From high resolution x-ray diffraction and x-ray photoelectron spectroscopy it is concluded that the observed p-type conductivities are a result of the promoted formation of PZn-4NO complex defects via the concurrent substitution of nitrogen at oxygen sites and phosphorus at zinc sites. The enhanced solubility and stability of acceptor defects in oxygen co-implanted dual-doped ZnO film are related to the reduction of oxygen vacancy defects at the surface. Our study demonstrates the prospect of the formation of stable p-type ZnO film through co-implantation.

  20. Hall and thermoelectric evaluation of p-type InAs

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, M.C., E-mail: magnus.wagener@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Wagener, V.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2009-12-15

    This paper compares the galvanometric and thermoelectric evaluation of the electrical characteristics of narrow gap semiconductors. In particular, the influence of a surface inversion layer is incorporated into the analysis of the temperature-dependent Hall and thermoelectric measurements of p-type InAs. The temperature at which the Seebeck coefficient of p-type material changes sign is shown to be unaffected by the presence of degenerate conduction paths. This finding consequently facilitated the direct determination of the acceptor density of lightly doped thin film InAs.

  1. Modeling and dynamics analysis of the fractional-order Buck—Boost converter in continuous conduction mode

    Science.gov (United States)

    Yang, Ning-Ning; Liu, Chong-Xin; Wu, Chao-Jun

    2012-08-01

    In this paper, the fractional-order mathematical model and the fractional-order state-space averaging model of the Buck—Boost converter in continuous conduction mode (CCM) are established based on the fractional calculus and the Adomian decomposition method. Some dynamical properties of the current-mode controlled fractional-order Buck—Boost converter are analysed. The simulation is accomplished by using SIMULINK. Numerical simulations are presented to verify the analytical results and we find that bifurcation points will be moved backward as α and β vary. At the same time, the simulation results show that the converter goes through different routes to chaos.

  2. A Continuous 3D-Graphene Network to Overcome Threshold Issues and Contact Resistance in Thermally Conductive Graphene Nanocomposites

    Directory of Open Access Journals (Sweden)

    Federico Conrado

    2017-01-01

    Full Text Available In order to overcome thermal resistance issues in polymeric matrix composites, self-standing graphene aerogels were synthetized and infiltrated with an epoxy resin, in order to create conductive preferential pathways through which heat can be easily transported. These continuous highly thermally conductive 3D-structures show, due to the high interconnection degree of graphene flakes, enhanced transport properties. Two kinds of aerogels were investigated, obtained by hydrothermal synthesis (HS and ice-templated direct freeze synthesis (DFS. Following HS method an isotropic structure is obtained, and following DFS method instead an anisotropic arrangement of graphene flakes results. The density of the structure can be tuned leading to a different amount of graphene inside the final composite. The residual oxygen, known to be detrimental to thermal properties, was removed by thermal treatment before the infiltration process. With 1,25 wt.% of graphene, using HS method, the thermal conductivity of the polymeric resin was increased by 80%, suggesting that this technique is a valid route to improve the thermal performance of graphene-based composites. When preferential orientation of the filler was present (DFS case, thermal conductivity was increased more than 25% with a graphene content of only 0,27 wt.%, demonstrating that oriented structures can further improve the thermal transport efficiency.

  3. CuNb3O8: A p-Type Semiconducting Metal Oxide Photoelectrode.

    Science.gov (United States)

    Joshi, Upendra A; Maggard, Paul A

    2012-06-07

    A new p-type CuNb3O8 polycrystalline photoelectrode was investigated and was determined to have indirect and direct bandgap sizes of 1.26 and 1.47 eV, respectively. The p-type polycrystalline film could be prepared on fluorine-doped tin oxide glass and yielded a cathodic photocurrent under visible-light irradiation (λ > 420 nm) with incident photon-to-current efficiencies of up to ∼6-7% and concomitant hydrogen evolution. A Mott-Schottky analysis yielded a flat band potential of +0.35 V versus RHE (pH = 6.3) and a calculated p-type dopant concentration of ∼7.2 × 10(15) cm(-3). The conduction band energies are found to be negative enough for the reduction of water under visible light irradiation. A hole mobility of ∼145 cm(2)/V·s was obtained from J(I)-V(2) measurements using the Mott-Gurney relation, which is ∼50% higher than that typically found for p-type Cu2O. DFT-based electronic structure calculations were used to probe the atomic and structural origins of the band gap transitions and carrier mobility. Thus, a new p-type semiconductor is discovered for potential applications in solar energy conversion.

  4. Synthesis of p-type and n-type nickel ferrites and associated electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Šutka, Andris, E-mail: andris.sutka@rtu.lv [Faculty of Material Science and Applied Chemistry, Riga Technical University, Paula Valdena 3, Riga, LV-1048 (Latvia); Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Pärna, Rainer [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia); Käämbre, Tanel [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Kisand, Vambola [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia)

    2015-01-01

    We used sol–gel auto combustion to synthesize nickel ferrites of p-type and n-type conductivity by controlling the relative amounts of nickel and iron during synthesis. The obtained samples have been characterized by XRD, FE-SEM, electrical measurements and XPS. We observe huge differences in the effect of grain size on the electrical resistivity between the p-type and the n-type material when the grain size increases from nano to micro scale during annealing at temperatures from 900 {sup o}C to 1300 {sup o}C. The observed resistivity decrease (due to grain size) is four orders of magnitude in the n-type nickel ferrite, whereas the p-type material remains virtually unaffected. We rationalize this drastic difference to stem from a reverse contrast of the surface (grain shell) versus bulk (grain core) conductivity between p- and n-type ferrite. With the grain shells in p-type the easier charge carrier path the effect of scatter at grain boundaries is accordingly diminished, whereas in the n-type charge transport properties are controlled by (the number of) grain boundaries in a conduction path.

  5. Realization of Ag-S codoped p-type ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tian Ning, E-mail: xtn9886@zju.edu.cn [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Li, Xiang; Lu, Zhong [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Chen, Yong Yue [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Sui, Cheng Hua [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Wu, Hui Zhen [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2014-10-15

    Highlights: • Ag-S codoped p-type ZnO thin films have been fabricated. • The films exhibit low resistivity and high Hall mobility and hole concentration. • A ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction has been fabricated and shows rectifying behaviors. - Abstract: Ag-S codoped ZnO films have been grown on quartz substrates by e-beam evaporation at low temperature (100 °C). The effects of Ag{sub 2}S content on the structural and electrical properties of the films were investigated. The results showed that 2 wt% Ag{sub 2}S doped films exhibited p-type conduction, with a resistivity of 0.0347 Ω cm, a Hall mobility of 9.53 cm{sup 2} V{sup −1} s{sup −1}, and a hole concentration of 1.89 × 10{sup 19} cm{sup −3} at room temperature. The X-ray photoelectron spectroscopy measurements showed that Ag and S have been incorporated into the films. To further confirm the p-type conduction of Ag-S codoped ZnO films, a ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction was fabricated and rectifying behaviors of which was measured. High electrical performance and low growth temperature indicate that Ag{sub 2}S is a promising dopant to fabricate p-type Ag-S codoped ZnO films.

  6. Modeling and dynamics analysis of the fractional-order Buck-Boost converter in continuous conduction mode

    Institute of Scientific and Technical Information of China (English)

    Yang Ning-Ning; Liu Chong-Xin; Wu Chao-Jun

    2012-01-01

    In this paper,the fractional-order mathematical model and the fractional-order state-space averaging model of the Buck-Boost converter in continuous conduction mode (CCM) are established based on the fractional calculus and the Adomian decomposition method.Some dynamical properties of the current-mode controlled fractional-order BuckBoost converter are analysed.The simulation is accomplished by using SIMULINK.Numerical simulations are presented to verify the analytical results and we find that bifurcation points will be moved backward as α and β vary.At the same time,the simulation results show that the converter goes through different routes to chaos.

  7. Modeling and Characteristics Analysis for a Buck-Boost Converter in Pseudo-Continuous Conduction Mode Based on Fractional Calculus

    Directory of Open Access Journals (Sweden)

    Ningning Yang

    2016-01-01

    Full Text Available In recent days, fractional calculus (FC has been accepted as a novel modeling tool that can extend the descriptive power of the traditional calculus. Fractional-order descriptiveness can increase the flexibility and degrees of freedom of the model by means of fractional parameters. Based on the fact that real capacitors and inductors are “intrinsic” fractional order, fractional calculus is introduced into the modeling process to establish a fractional-order state-space averaging model of the Buck-Boost converter in pseudo-continuous conduction mode (PCCM. Orders of the model are considered as extra parameters, and these parameters have significant influences on the performance of the model. The inductor current, the inductor current ripple, the amplitude of the output voltage, and the transfer functions of the fractional-order model are all related to orders. The contrast simulation experiments are conducted to investigate the performance of integer-order and fractional-order Buck-Boost converters in PCCM. Results of numerical and circuit simulations demonstrate that the proposed theoretical analysis is effective; the fractional-order model of the Buck-Boost converter in PCCM has certain theoretical and practical significance for modeling and performance analysis of other electrical or electronic equipment.

  8. Investigation of negative photoconductivity in p-type Pb1-xSnxTe film

    Science.gov (United States)

    Tavares, M. A. B.; da Silva, M. J.; Peres, M. L.; de Castro, S.; Soares, D. A. W.; Okazaki, A. K.; Fornari, C. I.; Rappl, P. H. O.; Abramof, E.

    2017-01-01

    We investigated the negative photoconductivity (NPC) effect that was observed in a p-type Pb1-xSnxTe film for temperatures varying from 300 K down to 85 K. We found that this effect is a consequence of defect states located in the bandgap which act as trapping levels, changing the relation between generation and recombination rates. Theoretical calculations predict contributions to the NPC from both conduction and valence bands, which are in accordance with the experimental observations.

  9. P-type electronic and thermal transport properties of Mg2Sn1-xSix

    Science.gov (United States)

    Kim, Sunphil; Wiendlocha, Bartlomiej; Heremans, Joseph P.

    2013-03-01

    P-type Mg2Sn doped with various acceptors(1)(2) has been studied as a potential thermoelectric material. Because of its narrow band gap and high lattice thermal conductivity, the zT values of the binary compound are limited: zTmax reported is 0.3(3). In this work, we synthesize and characterize p-type-doped Mg2Sn1-xSix with various acceptors. Silicon is added in order to widen the band gap and scatter the phonons. The conduction band degeneracy that yields excellent zT in n-type material in the Mg2Sn1-xSix alloy system unfortunately does not apply to p-type material. Thermomagnetic and galvanomagnetic properties (electrical resistivity, Seebeck, Hall, and Nernst coefficients) are measured, along with thermal conductivity and band gap measurements. Finally, zT values are reported. (1) H. Y. Chen et al. Journal of Electronic Materials, Vol. 38, No. 7, 2009 (2) S. Choi et al. Journal of Electronic Materials, Vol. 41, No. 6, 2012 (3) H. Y. Chen et al. Phys. Status Solidi A 207, No. 11, 2523-2531 (2010) The work is supported by the joint NSF/DOE program on thermoelectrics, NSF-CBET-1048622

  10. Development in p-type Doping of ZnO

    Institute of Scientific and Technical Information of China (English)

    YU Liping; ZHU Qiqiang; FAN Dayong; LAN Zili

    2012-01-01

    Zinc oxide (ZnO) is a wide band-gap material of the Ⅱ-Ⅵ group with excellent optical properties for optoelectronics applications,such as the flat panel displays and solar cells used in sports tournament.Despite its advantages,the application of ZnO is hampered by the lack of stable p-type doping.In this paper,the recent progress in this field was briefly reviewed,and a comprehensive summary of the research was carried out on ZnO fabrication methods and its electrical,optical,and magnetic properties were presented.

  11. Bi-Se doped with Cu, p-type semiconductor

    Science.gov (United States)

    Bhattacharya, Raghu Nath; Phok, Sovannary; Parilla, Philip Anthony

    2013-08-20

    A Bi--Se doped with Cu, p-type semiconductor, preferably used as an absorber material in a photovoltaic device. Preferably the semiconductor has at least 20 molar percent Cu. In a preferred embodiment, the semiconductor comprises at least 28 molar percent of Cu. In one embodiment, the semiconductor comprises a molar percentage of Cu and Bi whereby the molar percentage of Cu divided by the molar percentage of Bi is greater than 1.2. In a preferred embodiment, the semiconductor is manufactured as a thin film having a thickness less than 600 nm.

  12. Sputtering deposition of P-type SnO films with SnO₂ target in hydrogen-containing atmosphere.

    Science.gov (United States)

    Hsu, Po-Ching; Hsu, Chao-Jui; Chang, Ching-Hsiang; Tsai, Shiao-Po; Chen, Wei-Chung; Hsieh, Hsing-Hung; Wu, Chung-Chih

    2014-08-27

    In this work, we had investigated sputtering deposition of p-type SnO using the widely used and robust SnO2 target in a hydrogen-containing reducing atmosphere. The effects of the hydrogen-containing sputtering gas on structures, compositions, optical, and electrical properties of deposited SnOx films were studied. Results show that polycrystalline and SnO-dominant films could be readily obtained by carefully controlling the hydrogen gas ratio in the sputtering gas and the extent of reduction reaction. P-type conductivity was unambiguously observed for SnO-dominant films with traceable Sn components, exhibiting a p-type Hall mobility of up to ∼3 cm(2) V(-1) s(-1). P-type SnO thin-film transistors using such SnO-dominant films were also demonstrated.

  13. Electroforming-free resistive switching memory effect in transparent p-type tin monoxide

    KAUST Repository

    Hota, M. K.

    2014-04-14

    We report reproducible low bias bipolar resistive switching behavior in p-type SnO thin film devices without extra electroforming steps. The experimental results show a stable resistance ratio of more than 100 times, switching cycling performance up to 180 cycles, and data retention of more than 103 s. The conduction mechanism varied depending on the applied voltage range and resistance state of the device. The memristive switching is shown to originate from a redox phenomenon at the Al/SnO interface, and subsequent formation/rupture of conducting filaments in the bulk of the SnO layer, likely involving oxygen vacancies and Sn interstitials.

  14. Infrared absorption and visible transparency in heavily doped p-type BaSnO3

    Science.gov (United States)

    Li, Yuwei; Sun, Jifeng; Singh, David J.

    2017-01-01

    The recent experimental work shows that perovskite BaSnO3 can be heavily doped by K to become a stable p-type semiconductor. Here, we find that p-type perovskite BaSnO3 retains transparency for visible light while absorbing strongly in the infrared below 1.5 eV. The origin of the remarkable optical transparency even with heavy doping is that the interband transitions that are enabled by empty states at the top of the valence band are concentrated mainly in the energy range from 0.5 to 1.5 eV, i.e., not extending past the near IR. In contrast to n-type, the Burstein-Moss shift is slightly negative, but very small reflecting the heavier valence bands relative to the conduction bands.

  15. Comment on 'Electronic Properties of Red P-Type T12S5 Single Crystals'

    Institute of Scientific and Technical Information of China (English)

    M. Cankurtaran; H. (C)elik

    2007-01-01

    Recently, Gamal et al. [Chin. Phys. Lett. 22 (2005) 1530] reported the results of electrical conductivity, Hall effect and thermoelectric measurements on p-type Th2S5 single crystals. From the experimental data for the temperature dependence of differential thermoelectric power, Gamal et al. determined the values of 2.66 × 10-41 kg and 2.50 × 10-41 kg, respectively, for the effective masses of electrons and holes in p-type Tl2S5, which are about ten orders of magnitude smaller than the free electron mass (9.11 × 10-31 kg). We argue that the anomalously small values obtained for the effective mass of charge carriers in Tl2S5 have no physical significance.

  16. An integrated driving circuit implemented with p-type LTPS TFTs for AMOLED

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li-qing; WU Chun-ya; HAO Da-shou; YAO Ying; MENG Zhi-guo; XIONG Shao-zhen

    2009-01-01

    Based on the technology of low temperature poly silicon thin film transistors (poly-Si-TFTs), a novel p-type TFT AMOLED panel with self-scanned driving circuit is introduced in this paper. A shift register formed with novel p-type TFTs is pro-posed to realize the gate driver. A flip-latch cooperated with the shift register is designed to conduct the data writing. In order to verify the validity of the proposed design, the circuits are simulated with SILVACO TCAD tools, using the MODEL in which the parameters of LTPS TFTs were extracted from the LTPS TFTs made in our lab. The simulation results indicate that the circuit can fulfill the driving function.

  17. Piezoelectric Nanogenerator Using p-Type ZnO Nanowire Arrays

    KAUST Repository

    Lu, Ming-Pei

    2009-03-11

    Using phosphorus-doped ZnO nanowire (NW) arrays grown on silicon substrate, energy conversion using the p-type ZnO NWs has been demonstrated for the first time. The p-type ZnO NWs produce positive output voltage pulses when scanned by a conductive atomic force microscope (AFM) in contact mode. The output voltage pulse is generated when the tip contacts the stretched side (positive piezoelectric potential side) of the NW. In contrast, the n-type ZnO NW produces negative output voltage when scanned by the AFM tip, and the output voltage pulse is generated when the tip contacts the compressed side (negative potential side) of the NW. In reference to theoretical simulation, these experimentally observed phenomena have been systematically explained based on the mechanism proposed for a nanogenerator. © 2009 American Chemical Society.

  18. Perspectives of High-Temperature Thermoelectric Applications and p-type and n-type Aluminoborides

    Science.gov (United States)

    Mori, T.

    2016-10-01

    A need exists to develop high-temperature thermoelectric materials which can utilize high-temperature unutilized/waste heat in thermal power plants, steelworks, factories, incinerators, etc., and also focused solar power. The thermal power plant topping application is of potential high impact since it can sizably increase the efficiency of power plants which are the major supply of electrical power for many countries. Higher borides are possible candidates for their particular high-temperature stability, generally large Seebeck coefficients, α, and intrinsic low thermal conductivity. Excellent (|α| > 200 μV/K) p-type or n-type behavior was recently achieved in the aluminoboride YAl x B14 by varying the occupancy of Al sites, x. Finding p-type and n-type counterparts has long been a difficulty of thermoelectric research not limited to borides. This paper reviews possible high-temperature thermoelectric applications, and recent developments and perspectives of thermoelectric aluminoborides.

  19. Metal Fluoride Inhibition of a P-type H+ Pump

    Science.gov (United States)

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    The plasma membrane H+-ATPase is a P-type ATPase responsible for establishing electrochemical gradients across the plasma membrane in fungi and plants. This essential proton pump exists in two activity states: an autoinhibited basal state with a low turnover rate and a low H+/ATP coupling ratio and an activated state in which ATP hydrolysis is tightly coupled to proton transport. Here we characterize metal fluorides as inhibitors of the fungal enzyme in both states. In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H+-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state. Thus, the stability of the ATPase inhibitor complex decreased significantly when the pump transitioned from the activated to the basal state, particularly when using beryllium fluoride, which mimics the bound phosphate in the E2P conformational state. Taken together, our results indicate that the phosphate bond of the phosphoenzyme intermediate of H+-ATPases is labile in the basal state, which may provide an explanation for the low H+/ATP coupling ratio of these pumps in the basal state. PMID:26134563

  20. Realization of Cu-Doped p-Type ZnO Thin Films by Molecular Beam Epitaxy.

    Science.gov (United States)

    Suja, Mohammad; Bashar, Sunayna B; Morshed, Muhammad M; Liu, Jianlin

    2015-04-29

    Cu-doped p-type ZnO films are grown on c-sapphire substrates by plasma-assisted molecular beam epitaxy. Photoluminescence (PL) experiments reveal a shallow acceptor state at 0.15 eV above the valence band edge. Hall effect results indicate that a growth condition window is found for the formation of p-type ZnO thin films, and the best conductivity is achieved with a high hole concentration of 1.54 × 10(18) cm(-3), a low resistivity of 0.6 Ω cm, and a moderate mobility of 6.65 cm(2) V(-1) s(-1) at room temperature. Metal oxide semiconductor capacitor devices have been fabricated on the Cu-doped ZnO films, and the characteristics of capacitance-voltage measurements demonstrate that the Cu-doped ZnO thin films under proper growth conditions are p-type. Seebeck measurements on these Cu-doped ZnO samples lead to positive Seebeck coefficients and further confirm the p-type conductivity. Other measurements such as X-ray diffraction, X-ray photoelectron, Raman, and absorption spectroscopies are also performed to elucidate the structural and optical characteristics of the Cu-doped p-type ZnO films. The p-type conductivity is explained to originate from Cu substitution of Zn with a valency of +1 state. However, all p-type samples are converted to n-type over time, which is mostly due to the carrier compensation from extrinsic defects of ZnO.

  1. p-Type NiO Hybrid Visible Photodetector.

    Science.gov (United States)

    Mallows, John; Planells, Miquel; Thakare, Vishal; Bhosale, Reshma; Ogale, Satishchandra; Robertson, Neil

    2015-12-23

    A novel hybrid visible-light photodetector was created using a planar p-type inorganic NiO layer in a junction with an organic electron acceptor layer. The effect of different oxygen pressures on formation of the NiO layer by pulsed laser deposition shows that higher pressure increases the charge carrier density of the film and lowers the dark current in the device. The addition of a monolayer of small molecules containing conjugated π systems and carboxyl groups at the device interface was also investigated and with correct alignment of the energy levels improves the device performance with respect to the quantum efficiency, responsivity, and photogeneration. The thickness of the organic layer was also optimized for the device, giving a responsivity of 1.54 × 10(-2) A W(-1) in 460 nm light.

  2. Elucidating Functional Aspects of P-type ATPases

    DEFF Research Database (Denmark)

    Autzen, Henriette Elisabeth

    2015-01-01

    similar to that of the wild type (WT) protein. The discrepancy between the newly determined crystal structure of LpCopA and the functional manifestations of the missense mutation in human CopA, could indicate that LpCopA is insufficient in structurally elucidating the effect of disease-causing mutations...... cancer and pathogenic microbes. The goal of this Ph.D. dissertation was to functionally characterize SERCA1a and CopA from Legionella pneumophila (LpCopA) through a range of different methods within structural biology. Crystallographic studies of SERCA1a led to a newly determined crystal structure......P-type ATPases are proteins that act to maintain ion homeostasis and electrochemical gradients through the translocation of cations across cell membranes. Underscoring their significance in humans, dysfunction of the ATPases can lead to crucial diseases. Dysfunction of the sarco...

  3. Study on the p-type QWIP-LED device

    Institute of Scientific and Technical Information of China (English)

    ZHEN; Honglou; XIONG; Dayuan; ZHOU; Xuchang; LI; Ning; SHAO; Jun; LU; Wei

    2006-01-01

    A p-type quantum well infrared photodetector (QWIP) integrated with a light-emitting diode (LED) (named QWIP-LED) was fabricated and studied. The infrared photo-response spectrum was obtained from the device resistance variation and the near-infrared photo-emission intensity variation. A good agreement between these two spectra was observed, which demonstrates that the long-wavelength infrared radiation around 7.5 μm has been transferred to the near-infrared light at 0.8 μm by the photo-electronic process in the QWIP-LED structure. Moreover, the experimentally observed infrared response wavelength is in good agreement with the theoretical calculation value of 7.7 μm. The results on the upconversion of the infrared radiation will be very useful for the new infrared focal plane array technology.

  4. Comparing n- and p-type polycrystalline silicon absorbers in thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Deckers, J. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); ESAT, KU Leuven, Kardinaal Mercierlaan 94, B-3001 Heverlee, Leuven (Belgium); Bourgeois, E. [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Jivanescu, M. [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Leuven (Belgium); Abass, A. [Photonics Research Group (INTEC), Ghent University-imec, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); Van Gestel, D.; Van Nieuwenhuysen, K.; Douhard, B. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); D' Haen, J.; Nesladek, M.; Manca, J. [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Gordon, I.; Bender, H. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); Stesmans, A. [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Leuven (Belgium); Mertens, R.; Poortmans, J. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); ESAT, KU Leuven, Kardinaal Mercierlaan 94, B-3001 Heverlee, Leuven (Belgium)

    2015-03-31

    We have investigated fine grained polycrystalline silicon thin films grown by direct chemical vapor deposition on oxidized silicon substrates. More specifically, we analyze the influence of the doping type on the properties of this model polycrystalline silicon material. This includes an investigation of defect passivation and benchmarking of minority carrier properties. In our investigation, we use a variety of characterization techniques to probe the properties of the investigated polycrystalline silicon thin films, including Fourier Transform Photoelectron Spectroscopy, Electron Spin Resonance, Conductivity Activation, and Suns-Voc measurements. Amphoteric silicon dangling bond defects are identified as the most prominent defect type present in these layers. They are the primary recombination center in the relatively lowly doped polysilicon thin films at the heart of the current investigation. In contrast with the case of solar cells based on Czochralski silicon or multicrystalline silicon wafers, we conclude that no benefit is found to be associated with the use of n-type dopants over p-type dopants in the active absorber of the investigated polycrystalline silicon thin-film solar cells. - Highlights: • Comparison of n- and p-type absorbers for thin-film poly-Si solar cells • Extensive characterization of the investigated layers' characteristics • Literature review pertaining the use of n-type and p-type dopants in silicon.

  5. Neurolysis of the conducting neuroma-in-continuity in perinatal brachial plexus palsy - evaluation of the results of surgical treatment.

    Science.gov (United States)

    Gosk, Jerzy; Rutowski, Roman; Urban, Maciej; Wiącek, Roman; Mazurek, Piotr; Wnukiewicz, Witold

    2011-01-01

    The aim of the study was to evaluate the surgical treatment results of cases of perinatal brachial plexus palsy with presence of neuroma-in-continuity. Clinical material included 21 children, aged from 3.5 to 36 months, treated surgically between 1996 and 2005. The control examination included 19 children. The shortest postoperative observation period was 4 years. After surgical treatment during clinical evaluation of function dependent on localization of neuroma-in-continuity we observed the following: in upper injury in 1 child good shoulder and elbow function; in upper-middle injuries with neuroma-in-continuity in upper trunk good elbow function in 66.6%, good shoulder function in 83.3% of cases; in upper-middle injuries with neuroma-in-continuity in upper and middle trunk in 1 examined child good function of elbow, shoulder, and wrist; in total injuries with neuroma-in-continuity in upper trunk good elbow function in 75%, and good shoulder function in 50% of cases; in total injuries with neuroma-in-continuity in upper and middle trunk good elbow function in 66.6%, good shoulder function in 33.3%, good wrist function in 66.6% of cases; in total injuries with neuroma-in-continuity in lower trunk grade 2 of motor hand function and return of sensibility to a level of S3+. The choice of microsurgical technique during surgical treatment of perinatal brachial plexus palsies with neuroma-in-continuity should be based on the whole clinical and intraoperative view. The best results after neurolysis should be expected when neuroma-in-continuity is localized in the upper trunk, the injury corresponds to third degree on Sunderland's scale, and during electric stimulation a normal motor response can be obtained.

  6. Recycling of p-type mc-si Top Cuts into p-type mono c-Si Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bronsveld, P.C.P.; Manshanden, P.; Lenzmann, F.O. [ECN Solar Energy, Westerduinweg 3, P.O. Box 1, NL-1755 ZG Petten (Netherlands); Gjerstad, O. [Si Pro Holding AS, Ornesveien 3, P.O. Box 37, 8161, Glomfjord (Norway); Oevrelid, E.J. [SINTEF, Alfred Getz Vei 2, 7465, Trondheim (Norway)

    2013-07-01

    Solar cell results and material analysis are presented of 2 p-type Czochralski (Cz) ingots pulled from a charge consisting of 100% and 50% recycled multicrystalline silicon top cuts. The top cuts were pre-cleaned with a dedicated low energy consuming technology. No structure loss was observed in the bodies of the ingots. The performance of solar cells made from the 100% recycled Si ingot decreases towards the seed end of the ingot, which could be related to a non-optimal pulling process. Solar cells from the tail end of this ingot and from the 50% recycled Si ingot demonstrated an average solar cell efficiency of 18.6%. This is only 0.1% absolute lower than the efficiency of higher resistivity reference solar cells from commercially available wafers that were co-processed.

  7. P-Type Silicon Strip Sensors for the new CMS Tracker at HL-LHC

    Science.gov (United States)

    Adam, W.; Bergauer, T.; Brondolin, E.; Dragicevic, M.; Friedl, M.; Frühwirth, R.; Hoch, M.; Hrubec, J.; König, A.; Steininger, H.; Waltenberger, W.; Alderweireldt, S.; Beaumont, W.; Janssen, X.; Lauwers, J.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Beghin, D.; Brun, H.; Clerbaux, B.; Delannoy, H.; De Lentdecker, G.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, Th.; Léonard, A.; Luetic, J.; Postiau, N.; Seva, T.; Vanlaer, P.; Vannerom, D.; Wang, Q.; Zhang, F.; Abu Zeid, S.; Blekman, F.; De Bruyn, I.; De Clercq, J.; D'Hondt, J.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Python, Q.; Skovpen, K.; Van Mulders, P.; Van Parijs, I.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; Delaere, C.; Delcourt, M.; De Visscher, S.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Michotte, D.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Szilasi, N.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Härkönen, J.; Lampén, T.; Luukka, P.; Peltola, T.; Tuominen, E.; Tuovinen, E.; Eerola, P.; Tuuva, T.; Baulieu, G.; Boudoul, G.; Caponetto, L.; Combaret, C.; Contardo, D.; Dupasquier, T.; Gallbit, G.; Lumb, N.; Mirabito, L.; Perries, S.; Vander Donckt, M.; Viret, S.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bonnin, C.; Brom, J.-M.; Chabert, E.; Chanon, N.; Charles, L.; Conte, E.; Fontaine, J.-Ch.; Gross, L.; Hosselet, J.; Jansova, M.; Tromson, D.; Autermann, C.; Feld, L.; Karpinski, W.; Kiesel, K. M.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Pierschel, G.; Preuten, M.; Rauch, M.; Schael, S.; Schomakers, C.; Schulz, J.; Schwering, G.; Wlochal, M.; Zhukov, V.; Pistone, C.; Fluegge, G.; Kuensken, A.; Pooth, O.; Stahl, A.; Aldaya, M.; Asawatangtrakuldee, C.; Beernaert, K.; Bertsche, D.; Contreras-Campana, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Gallo, E.; Garay Garcia, J.; Hansen, K.; Haranko, M.; Harb, A.; Hauk, J.; Keaveney, J.; Kalogeropoulos, A.; Kleinwort, C.; Lohmann, W.; Mankel, R.; Maser, H.; Mittag, G.; Muhl, C.; Mussgiller, A.; Pitzl, D.; Reichelt, O.; Savitskyi, M.; Schuetze, P.; Walsh, R.; Zuber, A.; Biskop, H.; Buhmann, P.; Centis-Vignali, M.; Garutti, E.; Haller, J.; Hoffmann, M.; Lapsien, T.; Matysek, M.; Perieanu, A.; Scharf, Ch.; Schleper, P.; Schmidt, A.; Schwandt, J.; Sonneveld, J.; Steinbrück, G.; Vormwald, B.; Wellhausen, J.; Abbas, M.; Amstutz, C.; Barvich, T.; Barth, Ch.; Boegelspacher, F.; De Boer, W.; Butz, E.; Caselle, M.; Colombo, F.; Dierlamm, A.; Freund, B.; Hartmann, F.; Heindl, S.; Husemann, U.; Kornmayer, A.; Kudella, S.; Muller, Th.; Simonis, H. J.; Steck, P.; Weber, M.; Weiler, Th.; Anagnostou, G.; Asenov, P.; Assiouras, P.; Daskalakis, G.; Kyriakis, A.; Loukas, D.; Paspalaki, L.; Siklér, F.; Veszprémi, V.; Bhardwaj, A.; Dalal, R.; Jain, G.; Ranjan, K.; Bakhshiansohl, H.; Behnamian, H.; Khakzad, M.; Naseri, M.; Cariola, P.; Creanza, D.; De Palma, M.; De Robertis, G.; Fiore, L.; Franco, M.; Loddo, F.; Silvestris, L.; Maggi, G.; Martiradonna, S.; My, S.; Selvaggi, G.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Saizu, M. A.; Tricomi, A.; Tuve, C.; Barbagli, G.; Brianzi, M.; Ciaranfi, R.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Latino, G.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Scarlini, E.; Sguazzoni, G.; Strom, D.; Viliani, L.; Ferro, F.; Lo Vetere, M.; Robutti, E.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Pedrini, D.; Azzi, P.; Bacchetta, N.; Bisello, D.; Dall'Osso, M.; Pozzobon, N.; Tosi, M.; De Canio, F.; Gaioni, L.; Manghisoni, M.; Nodari, B.; Riceputi, E.; Re, V.; Traversi, G.; Comotti, D.; Ratti, L.; Alunni Solestizi, L.; Biasini, M.; Bilei, G. M.; Cecchi, C.; Checcucci, B.; Ciangottini, D.; Fanò, L.; Gentsos, C.; Ionica, M.; Leonardi, R.; Manoni, E.; Mantovani, G.; Marconi, S.; Mariani, V.; Menichelli, M.; Modak, A.; Morozzi, A.; Moscatelli, F.; Passeri, D.; Placidi, P.; Postolache, V.; Rossi, A.; Saha, A.; Santocchia, A.; Storchi, L.; Spiga, D.; Androsov, K.; Azzurri, P.; Arezzini, S.; Bagliesi, G.; Basti, A.; Boccali, T.; Borrello, L.; Bosi, F.; Castaldi, R.; Ciampa, A.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Magazzu, G.; Martini, L.; Mazzoni, E.; Messineo, A.; Moggi, A.; Morsani, F.; Palla, F.; Palmonari, F.; Raffaelli, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Bellan, R.; Costa, M.; Covarelli, R.; Da Rocha Rolo, M.; Demaria, N.; Rivetti, A.; Dellacasa, G.; Mazza, G.; Migliore, E.; Monteil, E.; Pacher, L.; Ravera, F.; Solano, A.; Fernandez, M.; Gomez, G.; Jaramillo Echeverria, R.; Moya, D.; Gonzalez Sanchez, F. J.; Vila, I.; Virto, A. L.; Abbaneo, D.; Ahmed, I.; Albert, E.; Auzinger, G.; Berruti, G.; Bianchi, G.; Blanchot, G.; Bonnaud, J.; Caratelli, A.; Ceresa, D.; Christiansen, J.; Cichy, K.; Daguin, J.; D'Auria, A.; Detraz, S.; Deyrail, D.; Dondelewski, O.; Faccio, F.; Frank, N.; Gadek, T.; Gill, K.; Honma, A.; Hugo, G.; Jara Casas, L. M.; Kaplon, J.; Kornmayer, A.; Kottelat, L.; Kovacs, M.; Krammer, M.; Lenoir, P.; Mannelli, M.; Marchioro, A.; Marconi, S.; Mersi, S.; Martina, S.; Michelis, S.; Moll, M.; Onnela, A.; Orfanelli, S.; Pavis, S.; Peisert, A.; Pernot, J.-F.; Petagna, P.; Petrucciani, G.; Postema, H.; Rose, P.; Tropea, P.; Troska, J.; Tsirou, A.; Vasey, F.; Vichoudis, P.; Verlaat, B.; Zwalinski, L.; Bachmair, F.; Becker, R.; di Calafiori, D.; Casal, B.; Berger, P.; Djambazov, L.; Donega, M.; Grab, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M.; Perozzi, L.; Roeser, U.; Starodumov, A.; Tavolaro, V.; Wallny, R.; Zhu, D.; Amsler, C.; Bösiger, K.; Caminada, L.; Canelli, F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hreus, T.; Kilminster, B.; Lange, C.; Maier, R.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Taroni, S.; Yang, Y.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Kaestli, H.-C.; Kotlinski, D.; Langenegger, U.; Meier, B.; Rohe, T.; Streuli, S.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Jacob, J.; Seif El Nasr-Storey, S.; Cole, J.; Hoad, C.; Hobson, P.; Morton, A.; Reid, I. D.; Auzinger, G.; Bainbridge, R.; Dauncey, P.; Hall, G.; James, T.; Magnan, A.-M.; Pesaresi, M.; Raymond, D. M.; Uchida, K.; Garabedian, A.; Heintz, U.; Narain, M.; Nelson, J.; Sagir, S.; Speer, T.; Swanson, J.; Tersegno, D.; Watson-Daniels, J.; Chertok, M.; Conway, J.; Conway, R.; Flores, C.; Lander, R.; Pellett, D.; Ricci-Tam, F.; Squires, M.; Thomson, J.; Yohay, R.; Burt, K.; Ellison, J.; Hanson, G.; Olmedo, M.; Si, W.; Yates, B. R.; Gerosa, R.; Sharma, V.; Vartak, A.; Yagil, A.; Zevi Della Porta, G.; Dutta, V.; Gouskos, L.; Incandela, J.; Kyre, S.; Mullin, S.; Patterson, A.; Qu, H.; White, D.; Dominguez, A.; Bartek, R.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Apresyan, A.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cheung, H. W. K.; Chramowicz, J.; Christian, D.; Cooper, W. E.; Deptuch, G.; Derylo, G.; Gingu, C.; Grünendahl, S.; Hasegawa, S.; Hoff, J.; Howell, J.; Hrycyk, M.; Jindariani, S.; Johnson, M.; Kahlid, F.; Lei, C. M.; Lipton, R.; Lopes De Sá, R.; Liu, T.; Los, S.; Matulik, M.; Merkel, P.; Nahn, S.; Prosser, A.; Rivera, R.; Schneider, B.; Sellberg, G.; Shenai, A.; Spiegel, L.; Tran, N.; Uplegger, L.; Voirin, E.; Berry, D. R.; Chen, X.; Ennesser, L.; Evdokimov, A.; Evdokimov, O.; Gerber, C. E.; Hofman, D. J.; Makauda, S.; Mills, C.; Sandoval Gonzalez, I. D.; Alimena, J.; Antonelli, L. J.; Francis, B.; Hart, A.; Hill, C. S.; Parashar, N.; Stupak, J.; Bortoletto, D.; Bubna, M.; Hinton, N.; Jones, M.; Miller, D. H.; Shi, X.; Tan, P.; Baringer, P.; Bean, A.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Wilson, G.; Ivanov, A.; Mendis, R.; Mitchell, T.; Skhirtladze, N.; Taylor, R.; Anderson, I.; Fehling, D.; Gritsan, A.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Monroy, J.; Siado, J.; Hahn, K.; Sevova, S.; Sung, K.; Trovato, M.; Bartz, E.; Gershtein, Y.; Halkiadakis, E.; Kyriacou, S.; Lath, A.; Nash, K.; Osherson, M.; Schnetzer, S.; Stone, R.; Walker, M.; Malik, S.; Norberg, S.; Ramirez Vargas, J. E.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kharchilava, A.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; McDermott, K.; Mirman, N.; Rinkevicius, A.; Ryd, A.; Salvati, E.; Skinnari, L.; Soffi, L.; Tao, Z.; Thom, J.; Tucker, J.; Zientek, M.; Akgün, B.; Ecklund, K. M.; Kilpatrick, M.; Nussbaum, T.; Zabel, J.; Betchart, B.; Covarelli, R.; Demina, R.; Hindrichs, O.; Petrillo, G.; Eusebi, R.; Osipenkov, I.; Perloff, A.; Ulmer, K. A.

    2017-06-01

    The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type. This paper describes the main measurement results and conclusions that motivated this decision.

  8. Above bandgap luminescence of p-type GaAs epitaxial layers

    Science.gov (United States)

    Sapriel, J.; Chavignon, J.; Alexandre, F.; Azoulay, R.; Sermage, B.; Rao, K.; Voos, M.

    1991-08-01

    New photoluminescence bands are observed in p-type GaAs epitaxial layers at 300 and 80 K, above the bandgap. These bands are independent of the nature of the dopant (Zn, Be, C) and of the growth technique (MBE or MOCVD). Their intensities increase as a function of the p doping (1 × 10 17 < p < 2 × 10 20cm-3) and peak at energies which correspond to transitions between the Γ 6, L 6 and X 6 minima of the conduction band and the Γ 8 and Γ 7 maxima of the valence band.

  9. (Ga,Fe)Sb: A p-type ferromagnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Nguyen Thanh; Anh, Le Duc; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-0033 (Japan)

    2014-09-29

    A p-type ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 3.9%–13.7%) has been grown by low-temperature molecular beam epitaxy (MBE) on GaAs(001) substrates. Reflection high energy electron diffraction patterns during the MBE growth and X-ray diffraction spectra indicate that (Ga,Fe)Sb layers have the zinc-blende crystal structure without any other crystallographic phase of precipitates. Magnetic circular dichroism (MCD) spectroscopy characterizations indicate that (Ga,Fe)Sb has the zinc-blende band structure with spin-splitting induced by s,p-d exchange interactions. The magnetic field dependence of the MCD intensity and anomalous Hall resistance of (Ga,Fe)Sb show clear hysteresis, demonstrating the presence of ferromagnetic order. The Curie temperature (T{sub C}) increases with increasing x and reaches 140 K at x = 13.7%. The crystal structure analyses, magneto-transport, and magneto-optical properties indicate that (Ga,Fe)Sb is an intrinsic ferromagnetic semiconductor.

  10. Photoconduction spectroscopy of p-type GaSb films

    Energy Technology Data Exchange (ETDEWEB)

    Shura, M.W., E-mail: Megersa.Shura@live.nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Wagener, V.; Botha, J.R.; Wagener, M.C. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    Excess carrier lifetimes (77 K) have been measured as function of the absorbed flux density in undoped p-type gallium antimonide films (GaSb/GaAs) using steady state photoconductivity measurements with the illumination wavelength of 1.1 {mu}m. Using the results from Hall effect measurements along with the relations describing the lifetimes of the excess minority carriers in the bulk of the films and at the surface, the theoretical values of the effective excess carrier lifetime in the materials were also calculated. Discrepancies between the experimental and theoretical results were described using a two-layer model, by considering the variation in the charge distribution within the layer due to the presence of surface states, as well as the band offset between the layer and the substrate. Theoretical modeling of the experimental result yields values of different parameters such as band bending at the surface, minimum value of Shockley-Read-Hall lifetime and maximum value of the surface recombination velocity.

  11. Constructal optimization of discrete and continuous-variable cross-section conducting path based on entransy dissipation rate minimization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Using constructal entransy dissipation rate minimization method based on discrete variable cross-section conducting path,constructal optimizations of elemental area with variable cross-section conducting path are performed,and the results are compared with the optimization results of elemental area with the constant cross-section conducting path.The comparison shows that the minimum mean temperature difference based on elemental area with variable cross-section conducting path increases and approaches a constant as the assembly’s order increases,but the minimum mean temperature difference based on elemental area with constant cross-section conducting path decreases and approaches a constant as the assembly’s order increases.The difference between them is caused by the different dimensionless mean temperature difference of the first order assembly.A universal constructal optimization method by self similar organization to improve heat transfer ability and its corresponding rule are proposed.With the constructal optimization method by self similar organization based on entransy dissipation rate minimization objective,the mean temperature difference approaches a constant as the assembly’s order increases.

  12. A Comparison between Boundary and Continuous Conduction Modes in Single Phase PFC Using 600V Range Devices

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2015-01-01

    in the 600V range. The measured switching energy is used to evaluate the devices performance in a conventional PFC. This data is used together with a mathematical model for prediction of the conducted electromagnetic interference (EMI). This allows comparing the different devices in BCM and CCM operation...

  13. Use of hexamethyldisiloxane for p-type microcrystalline silicon oxycarbide layers

    Directory of Open Access Journals (Sweden)

    Goyal Prabal

    2016-01-01

    Full Text Available The use of hexamethyldisiloxane (HMDSO as an oxygen source for the growth of p-type silicon-based layers deposited by Plasma Enhanced Chemical Vapor Deposition is evaluated. The use of this source led to the incorporation of almost equivalent amounts of oxygen and carbon, resulting in microcrystalline silicon oxycarbide thin films. The layers were examined with characterisation techniques including Spectroscopic Ellipsometry, Dark Conductivity, Fourier Transform Infrared Spectroscopy, Secondary Ion Mass Spectrometry and Transmission Electron Microscopy to check material composition and structure. Materials studies show that the refractive indices of the layers can be tuned over the range from 2.5 to 3.85 (measured at 600 nm and in-plane dark conductivities over the range from 10-8 S/cm to 1 S/cm, suggesting that these doped layers are suitable for solar cell applications. The p-type layers were tested in single junction amorphous silicon p-i-n type solar cells.

  14. Analytical solution to convection-radiation of a continuously moving fin with temperature-dependent thermal conductivity

    Directory of Open Access Journals (Sweden)

    Moradi Amir

    2013-01-01

    Full Text Available In this article, the simultaneous convection-radiation heat transfer of a moving fin of variable thermal conductivity is studied. The differential transformation method (DTM is applied for an analytic solution for heat transfer in fin with two different profiles. Fin profiles are rectangular and exponential. The accuracy of analytic solution is validated by comparing it with the numerical solution that is obtained by fourth-order Runge-Kutta method. The analytical and numerical results are shown for different values of the embedding parameters. DTM results show that series converge rapidly with high accuracy. The results indicate that the fin tip temperature increases when ambient temperature increases. Conversely, the fin tip temperature decreases with an increase in the Peclet number, convection-conduction and radiation-conduction parameters. It is shown that the fin tip temperature of the exponential profile is higher than the rectangular one. The results indicate that the numerical data and analytical method are in a good agreement with each other.

  15. Modeling of normal incidence absorption in p-type GaAs/AlGaAs quantum well infrared detectors

    Science.gov (United States)

    Brown, Gail J.; Szmulowicz, Frank

    1995-04-01

    The absorption of infrared radiation at normal incidence in p-type GaAs/AlGaAs quantum wells, unlike in n-type, is fundamentally allowed. We have measured and theoretically modeled the bound-to-continuum absorption in these p-type materials. The infrared absorption coefficient was calculated are based on the electronic structure, wave functions and optical matrix elements obtained from an 8 X 8 envelope-function approximation (EFA) calculation. The 8 X 8 EFA Hamiltonian incorporates the coupling between the heavy, light, spin-orbit, and conduction bands. In calculating the continuum states for bound-to- continuum intersubband absorption, we do not enclose the well in an artificial box with infinite walls. A comparison of the theoretical absorption and measured photoresponse results verified the accuracy of our model and provided a basis for optimizing the design of p-type quantum wells for infrared detection.

  16. Improved thermoelectric efficiency in p-type ZnSb through Zn deficiency

    Science.gov (United States)

    Guo, Qilong; Luo, Sijun

    2015-12-01

    We herein report a feasible approach to improve the thermoelectric performance of p-type ZnSb compound by Zn content regulation. It is found that Zn vacancies formed by Zn deficiency not only efficiently enhance the electrical conductivity due to the improved hole concentration but also markedly lower the lattice thermal conductivity on account of the reinforced point defect scattering of phonons. The ZnSb compound with a nominal 3 mol.% Zn deficiency shows a maximum thermoelectric figure of merit ZT of 0.8 at 700 K which is a 60% improvement over the pristine sample. The strategies of further enhancing the performance of ZnSb-based material have been discussed.

  17. Wet spinning of continuous polymer-free carbon-nanotube fibers with high electrical conductivity and strength

    Science.gov (United States)

    Mukai, Ken; Asaka, Kinji; Wu, Xueli; Morimoto, Takahiro; Okazaki, Toshiya; Saito, Takeshi; Yumura, Motoo

    2016-05-01

    We report on the fabrication of polymer-free carbon nanotube (CNT) fibers by a novel wet spinning method combined with a very easy and straightforward fabrication process. These fibers exhibited high electrical conductivity (14,284 ± 169 S·cm-1) and tensile strength (887 ± 37 MPa). Such high performance was made possible by the preparation of free-standing CNT fibers from a surfactant solution containing uniformly dispersed CNTs, despite the use of an organic coagulating solvent and subsequent stretching to align the CNTs in the fiber.

  18. The electrical properties of photodiodes based on nanostructure gallium doped cadmium oxide/p-type silicon junctions

    Science.gov (United States)

    Çavaş, M.; Yakuphanoğlu, F.; Karataş, Ş.

    2017-01-01

    Gallium doped cadmium-oxide (CdO: Ga) thin films were successfully deposited by sol-gel spin coating method on p-type Si substrate. The electrical properties of the photodiode based on nanostructure Ga doped n-CdO/p-Si junctions were investigated. The current-voltage (I-V) characteristics of the structure were investigated under various light intensity and dark. It was observed that generated photocurrent of the Au/n-CdO/p-Si junctions depended on light intensity. The capacitance-voltage and conductance-voltage measurements were carried out for this diode in the frequency range between 100 and 1000 kHz at room temperature by steps of 100 kHz. The capacitance decreased with increasing frequency due to a continuous distribution of the interface states. These results suggested that the Au/n-CdO/p-Si Schottky junctions could be utilized as a photosensor. Furthermore, the voltage and frequency dependence of series resistance were calculated from the C-V and G/ω-V measurements and plotted as functions of voltage and frequency. The distribution profile of R S -V gave a peak in the depletion region at low frequencies and disappeared with increasing frequencies.

  19. Computationally efficient models for simulation of non-ideal DC–DC converters operating in continuous and discontinuous conduction modes

    Indian Academy of Sciences (India)

    Challa Mohana Krishna; Saritha B; Narayanan G

    2015-10-01

    This paper discusses dynamic modeling of non-isolated DC–DC converters (buck, boost and buck–boost) under continuous and discontinuous modes of operation. Three types of models are presented for each converter, namely, switching model, average model and harmonic model. These models include significant nonidealities of the converters. The switching model gives the instantaneous currents and voltages of the converter. The average model provides the ripple-free currents and voltages, averaged over a switching cycle. The harmonic model gives the peak to peak values of ripple in currents and voltages. The validity of all these models is established by comparing the simulation results with the experimental results from laboratory prototypes, at different steady state and transient conditions. Simulation based on a combination of average and harmonic models is shown to provide all relevant information as obtained from the switching model, while consuming less computation time than the latter.

  20. The development of p-type silicon detectors for the high radiation regions of the LHC

    CERN Document Server

    Hanlon, M D L

    1998-01-01

    This thesis describes the production and characterisation of silicon microstrip detectors and test structures on p-type substrates. An account is given of the production and full parameterisation of a p-type microstrip detector, incorporating the ATLAS-A geometry in a beam test. This detector is an AC coupled device incorporating a continuous p-stop isolation frame and polysilicon biasing and is typical of n-strip devices proposed for operation at the LHC. It was successfully read out using the FELix-128 analogue pipeline chip and a signal to noise (s/n) of 17+-1 is reported, along with a spatial resolution of 14.6+-0.2 mu m. Diode test structures were fabricated on both high resistivity float zone material and on epitaxial material and subsequently irradiated with 24 GeV protons at the CERN PS up to a dose of (8.22+-0.23) x 10 sup 1 sup 4 per cm sup 2. An account of the measurement program is presented along with results on the changes in the effective doping concentration (N sub e sub f sub f) with irradiat...

  1. Effective Synthesis and Recovery of Silver Nanowires Prepared by Tapered Continuous Flow Reactor for Flexible and Transparent Conducting Electrode

    Directory of Open Access Journals (Sweden)

    Hyung Duk Yun

    2016-01-01

    Full Text Available Silver nanowires (AgNWs with high aspect ratio were obtained utilizing a tapered tubular reactor by the polyol process. The tapered tubular type flow reactor allowed us to obtain nanowires in high yield without defects that is generally encountered in a closed reactor due to excessive shearing for a long time. After reaction the AgNWs were precipitated in the aqueous solution with the aid of a hydrogen bond breaker and were recovered effectively without using a high-cost centrifugation process. Dispersion of the AgNWs were used to prepare transparent conducting electrode (TCE films by a spray coating method, which showed 86% transmittance and 90 Ωsq−1 sheet resistance.

  2. A study on removal of cobalt from the primary coolant by continuous electrode-ionization with various conducting spacers

    Energy Technology Data Exchange (ETDEWEB)

    Yeon, K.H.; Song, J.H.; Moon, S.H. [Department of Environmental Science and Engineering, Kwangju Inst. of Science and Technology (K-JIST) (Korea, Republic of)

    2002-07-01

    CEDI is a hybrid separation system of electrodialysis and ion exchange processes. This system does not require chemicals to regenerate the ion exchange resin and to concentrate the wastewater. In a CEDI system, the ion exchange resin bed plays a major role in the reduction of the high electrical resistance in the dilute compartment, while the ion exchange membranes lead to depletion and concentration of the solutions in the dilute compartment and concentrate compartment, respectively. The production of high purity water in the primary coolant of a nuclear power plant was investigated using a CEDI process along with various ion-conducting spacers, such as an ion exchange resin (IX), polyurethane-coated ion exchange beads (IEPU), and an ion exchange textile (IET). The ion exchange resin was introduced into the ion-depleting compartments of an electrodialysis (ED) stack, and has been used to reduce the electrical resistance of the stack since ED cannot be applied economically to the treatment of dilute solutions due to their high electrical resistances and the development of the polarization phenomena. However, packing the resin beads in the compartment and assembling the stack is laborious work, while attaining a free flowing solution is difficult because the resin beads are driven downward by gravity in the diluted compartment. Nevertheless, a resin-packed ED stack has recently been developed by Millipore, and is now commercially available from U.S. Filter as industrial units. We set out to prepare improved ion-conducting materials suitable for use in CEDI stacks. To this end, IEPU was prepared using a blending method that produces mixtures of resin beads and powder by allophanate/biuret cross-linking. IET was prepared by the radiation grafting of styrene-fulfonic acid or trimethyl-ammonium chloride onto polypropylene non-woven fabric. (authors)

  3. Effects of 2450 MHz continuous wave microwave radiation and isothermal conduction on canine platelet aggregometry, survival and margination

    Energy Technology Data Exchange (ETDEWEB)

    Bushberg, J.T.

    1981-01-01

    The effect of 2450 MHz microwave radiation and isothermal conduction ex vivo exposures on canine platelets was analyzed in vitro by studying adenosine-5'-diphosphate activated aggregation and in vivo by studying the survival, distribution and physiological integrity of reinfused autologous Indium-111 labeled platelets. Platelet rich plasma (PRP) from eight healthy dogs was subjected to microwave irradiation at 10 MW/cm/sup 2/ and at 50 MW/cm/sup 2/ for 10, 100, 600, 900, 1800 seconds and at 100 MW/cm/sup 2/ for 10, 100, and 600 seconds. Aggregometry analysis was performed immediately after exposure and 10 minutes post-exposure. No significant perturbations were observed following microwave exposure of 10 MW/cm/sup 2/. At higher power densities six specific types of aggregation phenomena were demonstrated: (1) Hyperaggregation, (2) Decreased Velocity Reduced Hyperaggregation, (3) Recovery, (4) Decreased Velocity Delayed Hyperaggregation, (5) Reversible Afunctionality, and (6) Irreversible Afunctionality. The absence of equivalent aggregation responses with isothermal conduction heating (extraisothermal effects) was attributed to differences in heating rate and not to nonthermal microwave-specific effects. Scintigraphic and survival kinetic studies were performed following power density/exposure time combinations. PRP samples I and IV displayed normal survival half-times; however, exposure I resulted in a depressed 15-minute post-reinfusion circulating percentage (CP/sub 15/) of 29% compared to 61% for the control sample. Exposure of groups II and III resulted in a dramatic reduction in the CP/sub 15/ (i.e., 18% and 1.3% respectively) and survival half-times. Margination of the labeled platelets was divided between the spleen, liver and blood pool.

  4. Thermal oxidation of Ni films for p-type thin-film transistors

    KAUST Repository

    Jiang, Jie

    2013-01-01

    p-Type nanocrystal NiO-based thin-film transistors (TFTs) are fabricated by simply oxidizing thin Ni films at temperatures as low as 400 °C. The highest field-effect mobility in a linear region and the current on-off ratio are found to be 5.2 cm2 V-1 s-1 and 2.2 × 103, respectively. X-ray diffraction, transmission electron microscopy and electrical performances of the TFTs with "top contact" and "bottom contact" channels suggest that the upper parts of the Ni films are clearly oxidized. In contrast, the lower parts in contact with the gate dielectric are partially oxidized to form a quasi-discontinuous Ni layer, which does not fully shield the gate electric field, but still conduct the source and drain current. This simple method for producing p-type TFTs may be promising for the next-generation oxide-based electronic applications. © 2013 the Owner Societies.

  5. Lateral photovoltaic effect in p-type silicon induced by surface states

    Science.gov (United States)

    Huang, Xu; Mei, Chunlian; Gan, Zhikai; Zhou, Peiqi; Wang, Hui

    2017-03-01

    A colossal lateral photovoltaic effect (LPE) was observed at the surface of p-type silicon, which differs from the conventional thought that a large LPE is only observed in Schottky junctions and PN junctions consisting of several layers with different conductivities. It shows a high sensitivity of 499.24 mV/mm and an ultra-broadband spectral responsivity (from 405 nm to 980 nm) at room temperature, which makes it an attractive candidate for near-infrared detection. We propose that this phenomenon can be understood by considering the surface band bending near the surface of p-Si induced by charged surface states. The energy band diagrams of the samples are shown based on X-ray photoelectron spectroscopy suggesting the correlation between the LPE and surface band bending. The conjectures are validated by changing the surface states of p-type silicon using Ni nano-films. These findings reveal a generation mechanism of the LPE and may lead to p-Si based, broadband-responsivity, low-cost, and high-precision optical and optoelectronic applications.

  6. Properties of In–N codoped p-type ZnO nanorods grown through a two-step chemical route

    Energy Technology Data Exchange (ETDEWEB)

    Duta, M.; Mihaiu, S.; Munteanu, C. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Anastasescu, M., E-mail: manastasescu@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Osiceanu, P.; Marin, A.; Preda, S. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Nicolescu, M., E-mail: mnicolescu2006@yahoo.com [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Modreanu, M. [Tyndall National Institute, University College, Cork (Ireland); Zaharescu, M.; Gartner, M. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania)

    2015-07-30

    Highlights: • p-Type ZnO film codoped with In, N on glass substrate was obtained. • The films were prepared by sol–gel followed by hydrothermal method. • Influence of annealing regimes on opto-electrical properties was studied. • Thin films morphology consists of interconnected, randomly oriented nanorods. • 3.31 × 10{sup 17} cm{sup −3}carrier concentration and 85% transmission were obtained at 500 °C. - Abstract: By codoping with a donor–acceptor pair through a two-step chemical method we have succeed to obtain p-type ZnO thin films on glass. Firstly, a thin undoped ZnO seed layer was deposited by sol–gel method followed by the deposition of In–N codoped ZnO film obtained through the hydrothermal technique. The influence of post-deposition annealing temperature (100 °C, 300 °C and 500 °C) on the samples was investigated from a structural, chemical, morphological and optoelectrical point of view. X-ray diffractometry (XRD), infrared ellipsometry and X-ray photoelectron spectroscopy (XPS) analyses have confirmed the codoped nature of the ZnO thin films. The XRD pattern analysis has established the films have wurtzite nanocrystalline structure, the crystallite sizes varying between 10 nm and 13 nm with the annealing temperature. Continuous and homogenous films with nanorods surface morphology has been obtained, as visualized by scanning electron microscopy measurements. Hall Effect measurements have established that all samples, regardless of annealing temperature, showed p-type conduction due to the successful incorporation of nitrogen in the film, with the highest carrier concentration registered at 500 °C. This is in good correlation with the nitrogen content in the films as revealed from XPS. In all samples, the XPS depth profiling has shown a nitrogen gradient with higher elemental concentration at the surface.

  7. Ethical issues in administrative continuous improvement. Applying the concept of prior notification to the conduct of firm trials.

    Science.gov (United States)

    Goldberg, H I

    1990-09-01

    Consensus exists concerning the distinctions to be drawn between clinical practice and research. When the latter is undertaken, established regulations require that protocols including plans for obtaining subjects' informed consent be submitted to Institutional Review Boards for approval. Less consensus or codification exists concerning evaluations conducted by managers in health care settings. The recent development of firm systems, in which randomized, controlled designs are employed to evaluate administrative interventions, provides a unique context in which to consider whether the subjects of administrative evaluations should be afforded protections granted subjects of clinical research. Accordingly, the history of firm trials from an ethical perspective is reviewed. At the University of Washington, participants of such studies are informed through the process of prior notification, an adaptation of procedures employed widely to inform patients that records or specimens may be used in epidemiologic or biomedical research. Prior notification appears to be a useful refinement of the firm system methodology, one that may have application to managerial manipulations in other arenas.

  8. Ultraviolet light-emitting diodes with polarization-doped p-type layer

    Science.gov (United States)

    Hu, Wenxiao; Qin, Ping; Song, Weidong; Zhang, Chongzhen; Wang, Rupeng; Zhao, Liangliang; Xia, Chao; Yuan, Songyang; Yin, Yian; Li, Shuti

    2016-09-01

    We report ultraviolet light emitting diode (LEDs) with polarization doped p-type layer. Fabricated LEDs with polarization doped p-type layer exhibited reduced forward voltage and enhanced light output power, compared to those with traditional p-type AlGaN layer. The improvement is attributed to improved hole concentration and the smooth valence band by the polarization enhanced p-type doping. Our simulated results reveal that this p-type layer can further enhance the performance of ultraviolet LEDs by removing the electron blocking layer (EBL).

  9. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    Science.gov (United States)

    Ambade, Swapnil B.; Mane, R. S.; Kale, S. S.; Sonawane, S. H.; Shaikh, Arif V.; Han, Sung-Hwan

    2006-12-01

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu 2- xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm 2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  10. How thermoelectric properties of p-type Tl-filled skutterudites are improved

    Directory of Open Access Journals (Sweden)

    Donghun Kim

    2013-09-01

    Full Text Available The high-temperature thermoelectric properties of p-type Tl-filled skutterudites TlxFe1Co3Sb12 (x = 0, 0.2, 0.4, 0.6, and 0.8 were examined. While samples with x ≤ 0.4 were single-phase Tl-filled skutterudite, samples with x = 0.6 and 0.8 were composed of two phases: TlxFe1Co3Sb12 (x ≈ 0.4 as the matrix phase and a Tl-Fe-Sb ternary alloy. The thermal conductivity (κ was reduced effectively by Tl addition, but the secondary phase increased κ slightly. The maximum value of the dimensionless figure of merit ZT (=S2T/ρ/κ, where T is the absolute temperature was 0.36 at 723 K for Tl0.2Fe1Co3Sb12.

  11. Nanoscale Cross-Point Resistive Switching Memory Comprising p-Type SnO Bilayers

    KAUST Repository

    Hota, Mrinal Kanti

    2015-02-23

    Reproducible low-voltage bipolar resistive switching is reported in bilayer structures of p-type SnO films. Specifically, a bilayer homojunction comprising SnOx (oxygen-rich) and SnOy (oxygen-deficient) in nanoscale cross-point (300 × 300 nm2) architecture with self-compliance effect is demonstrated. By using two layers of SnO film, a good memory performance is obtained as compared to the individual oxide films. The memory devices show resistance ratio of 103 between the high resistance and low resistance states, and this difference can be maintained for up to 180 cycles. The devices also show good retention characteristics, where no significant degradation is observed for more than 103 s. Different charge transport mechanisms are found in both resistance states, depending on the applied voltage range and its polarity. The resistive switching is shown to originate from the oxygen ion migration and subsequent formation/rupture of conducting filaments.

  12. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ambade, Swapnil B. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Mane, R.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Kale, S.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Sonawane, S.H. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Shaikh, Arif V. [Department of Electronic Science, AKI' s Poona College of Arts, Science and Commerce, Camp, Pune 411 001 (India); Han, Sung-Hwan [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of)]. E-mail: shhan@hanyang.ac.kr

    2006-12-15

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 deg. C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu{sub 2-x}Se phase was confirmed by XRD pattern and spherical grains of 30 {+-} 4 - 40 {+-} 4 nm in size aggregated over about 130 {+-} 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm{sup 2} light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  13. Wide bandgap n-type and p-type semiconductor porous junction devices as photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yuan-Pai; Horng, Sheng-Fu [Institute of Electronics Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chao, Yu-Chiang; Meng, Hsin-Fei [Institute of Physics, National Chiao Tung University, Hsinchu 300, Taiwan (China); Zan, Hsiao-Wen, E-mail: yuchiangchao@gmail.com, E-mail: meng@mail.nctu.edu.tw [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2011-10-12

    In junction absorber photovoltaics doped wide bandgap n-type and p-type semiconductors form a porous interpenetrating junction structure with a layer of low bandgap absorber at the interface. The doping concentration is high enough such that the junction depletion width is smaller than the pore size. The highly conductive neutral region then has a dentrite shape with fingers reaching the absorber to effectively collect the photo-carriers swept out by the junction electric field. With doping of 10{sup 19} cm{sup -3} corresponding to a depletion width of 25 nm, pore size of 32 nm, absorber thickness close to exciton diffusion length of 17 nm, absorber bandgap of 1.4 eV and carrier mobility over 10{sup -5} cm{sup 2} V{sup -1} s{sup -1}, numerical calculation shows the power conversion efficiency is as high as 19.4%. It rises to 23% for a triplet exciton absorber.

  14. InP nanowire p-type doping via Zinc indiffusion

    Science.gov (United States)

    Haggren, Tuomas; Otnes, Gaute; Mourão, Renato; Dagyte, Vilgaile; Hultin, Olof; Lindelöw, Fredrik; Borgström, Magnus; Samuelson, Lars

    2016-10-01

    We report an alternative pathway for p-type InP nanowire (NW) doping by diffusion of Zn species from the gas phase. The diffusion of Zn was performed in a MOVPE reactor at 350-500 °C for 5-20 min with either H2 environment or additional phosphorus in the atmosphere. In addition, Zn3P2 shells were studied as protective caps during post-diffusion annealing. This post-diffusion annealing was performed to outdiffuse and activate Zn in interstitial locations. The characterization methods included photoluminescence and single NW conductivity and carrier concentration measurements. The acquired carrier concentrations were in the order of >1017 cm-3 for NWs without post-annealing, and up to 1018 cm-3 for NWs annealed with the Zn3P2 shells. The diffused Zn caused redshift to the photoluminescence signal, and the degree of redshift depended on the diffusion process.

  15. Study of p-type AlN-doped SnO2 thin films and its transparent devices

    Science.gov (United States)

    Wu, Y. J.; Liu, Y. S.; Hsieh, C. Y.; Lee, P. M.; Wei, Y. S.; Liao, C. H.; Liu, C. Y.

    2015-02-01

    The electrical properties of transparent Al-doped tin oxide (SnO2), N-doped SnO2, and AlN-doped SnO2 thin films were studied. The Al-doped tin oxide (SnO2) thin films all show n-type conduction regardless the annealing condition. The n-type conduction of the as-deposited N-doped SnO2, and AlN-doped SnO2 thin films could be converted to p-type conduction by annealing the films at an elevated temperature of 450 °C. XPS analysis verified that the substitution of N ions in the O ion sites in the annealed N-doped SnO2 and AlN-doped SnO2 thin films were responsible for the n-p conduction transition. The conduction of the annealed N-doped SnO2 and AlN-doped SnO2 thin films could be converted back to n-type conduction by thermally annealing the films at higher temperature, over 450 °C. The p-n conduction transition is related with the outgassing of N ions in the p-type N-doped SnO2 and AlN-doped SnO2 thin films. Remarkably, we found that the Al content can retard the outgassing of N ions in the p-type N-doped SnO2 and AlN-doped SnO2 thin films and prolong the p-n conduction transition temperature above 600 °C. XPS analysis revealed that the formation of the Snsbnd Nsbnd Al bond improved the stability of the N ions in the AlN-doped SnO2 thin films. I-V curve of the p-type AlN-doped SnO2/n-type fluorine-doped SnO2 junction exhibited clear p-n junction characteristics, a low leakage current under the revised bias (1.13 × 10-5 A at -5 V), and a low turn-on voltage (3.24 V). p-Type AlN-doped SnO2/n-type fluorine-doped SnO2 junction exhibited excellent transmittance (over 90%) in the visible region (470-750 nm).

  16. First-principles study of p-type ZnO by S-Na co-doping

    Science.gov (United States)

    Tan, Xingyi; Li, Qiang; Zhu, Yongdan

    2017-08-01

    Using the first-principles method based on the density functional theory, the formation energy, electronic structures of S-Na co-doping in ZnO were calculated. The calculated results show that NaZn-SO have smaller formation energy than Nain-SO in energy ranges from -3.10 to 0 eV of {μ }{{O}}, indicating that it opens up a new opportunity for growth the p-type ZnO. The band structure shows that the NaZn system is a p-type direct-band-gap semiconductor material and the calculated band gap (0.84 eV) is larger than pure ZnO (0.74 eV). The NaZn-SO system is also a p-type semiconductor material with a direct band gap (0.80 eV). The influence of S-Na co-doping in ZnO on p-type conductivity is also discussed. The effective masses of NaZn-SO are larger than effective masses of NaZn and the NaZn-SO have more hole carriers than NaZn, meaning the hole in the NaZn-SO system may have a better carrier transfer character. So we inferred that NaZn-SO should be a candidate of p-type conduction. Project supported by the Natural Science Foundation of Hubei Province, China (Nos. 2014CFB342, 2014CFB619) and the Doctoral Foundation for Scientific Research of Hubei University for Nationalities (No. MY2013B020).

  17. New photovoltaic devices based on the sensitization of p-type semiconductors: challenges and opportunities.

    Science.gov (United States)

    Odobel, Fabrice; Le Pleux, Loïc; Pellegrin, Yann; Blart, Errol

    2010-08-17

    Because solar energy is the most abundant renewable energy resource, the clear connection between human activity and global warming has strengthened the interest in photovoltaic science. Dye-sensitized solar cells (DSSCs) provide a promising low-cost technology for harnessing this energy source. Until recently, much of the research surrounding DSSCs had been focused on the sensitization of n-type semiconductors, such as titanium dioxide (Gratzel cells). In an n-type dye-sensitized solar cell (n-DSSC), an electron is injected into the conduction band of an n-type semiconductor (n-SC) from the excited state of the sensitizer. Comparatively few studies have examined the sensitization of wide bandgap p-type semiconductors. In a p-type DSSC (p-DSSC), the photoexcited sensitizer is reductively quenched by hole injection into the valence band of a p-type semiconductor (p-SC). The study of p-DSSCs is important both to understand the factors that control the rate of hole photoinjection and to aid the rational design of efficient p-DSSCs. In theory, p-DSSCs should be able to work as efficiently as n-DSSCs. In addition, this research provides a method for preparing tandem DSSCs consisting of a TiO(2)-photosensitized anode and a photosensitized p-type SC as a cathode. Tandem DSSCs are particularly important because they represent low-cost photovoltaic devices whose photoconversion efficiencies could exceed 15%. This Account describes recent research results on p-DSSCs. Because these photoelectrochemical devices are the mirror images of conventional n-DSSCs, they share some structural similarities, but they use different materials and have different charge transfer kinetics. In this technology, nickel oxide is the predominant p-SC material used, but much higher photoconversion efficiencies could be achieved with new p-SCs materials with deeper valence band potential. Currently, iodide/triiodide is the main redox mediator of electron transport within these devices, but we expect

  18. Fabrication of p-type ZnSe:Sb nanowires for high-performance ultraviolet light photodetector application.

    Science.gov (United States)

    Nie, Biao; Luo, Lin-Bao; Chen, Jing-Jing; Hu, Ji-Gang; Wu, Chun-Yan; Wang, Li; Yu, Yong-Qiang; Zhu, Zhi-Feng; Jie, Jian-Sheng

    2013-03-08

    p-type ZnSe nanowires (NWs) with tunable electrical conductivity were fabricated on a large scale by evaporating a mixed powder composed of ZnSe and Sb in different ratios. According to the structural characterization, the Sb-doped ZnSe NWs are of single crystalline form and grow along the [001] direction. The presence of Sb in the ZnSe NWs was confirmed by XPS spectra. Electrical measurement of a single ZnSe:Sb NW based back-gate metal-oxide field-effect-transistor reveals that all the doped NWs exhibit typical p-type conduction characteristics, and the conductivity can be tuned over eight orders of magnitude, from 6.36 × 10(-7) S cm(-1) for the undoped sample to ∼37.33 S cm(-1) for the heavily doped sample. A crossed p-n nano-heterojunction photodetector made from the as-doped nanostructures displays pronounced rectification behavior, with a rectification ratio as high as 10(3) at ±5 V. Remarkably, it exhibits high sensitivity to ultraviolet light illumination with good reproducibility and quick photoresponse. Finally, the work mechanism of such a p-n junction based photodetector was elucidated. The generality of the above result suggests that the as-doped p-type ZnSe NWs will find wide application in future optoelectronics devices.

  19. Structural change and power factor enhancement of thermoelectric p-type films

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, Katrin; Leipner, Hartmut; Heyroth, Frank [Interdisziplinaeres Zentrum fuer Materialwissenschaften, Martin-Luther-Universitaet 06099 Halle (Germany); Stordeur, Matthias; Engers, Bernd [angaris GmbH, Heinrich-Damerow-Str. 1, 06120 Halle (Germany)

    2008-07-01

    By sputter-deposition thin films of the thermoelectric effective p-type compound semiconductor (Bi{sub 0.15}Sb{sub 0.85}){sub 2}Te{sub 3} were prepared. For the first time a distinct increase of the electrical conductivity s was observed after heating of the as-deposited films and afterwards cooling. For the enlightenment of this typical behavior, which seems to be similar found for phase change materials consisting of (Ge, Sb, Te)-alloys, also the Seebeck (S) and the Hall coefficient were measured. It was established that the increase of the electrical conductivity is not connected with an expected decrease of the Seebeck coefficient, because the charge carrier density is reduced but at the same time the hole mobility is increasing. Corresponding analytical investigations by XRD, EDX, and REM shows that besides a grain growth in the polycrystalline films a Te-rich phase appears after the heat treatment. The increase of the electrical conductivity at nearly unchanged Seebeck coefficient can be exploited for the enhancement of the film power factor (S{sup 2}s). This is important for the efficiency of thermoelectric thin films devices as miniaturized coolers, generators, and sensors. Nevertheless for a quantitative interpretation of the presented new experimental results further investigations and theoretical considerations are required.

  20. NbFeSb based p-type half-Heusler for power generation applications

    Science.gov (United States)

    Joshi, Giri; He, Ran; Engber, Michael; Samsonidze, Georgy; Pantha, Tej; Dahal, Ekraj; Dahal, Keshab; Yang, Jian; Lan, Yucheng; Kozinsky, Boris; Ren, Zhifeng

    2015-03-01

    We report a peak dimensionless figure-of-merit (ZT) of ~1 at 700 oC in nanostructured p-type Nb0.6Ti0.4FeSb0.95Sn0.05composition. Even though the power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is improved by 25% in comparison to the previously reported p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, the ZT value is not increased due to a higher thermal conductivity. However, the higher power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition led to a 15% increase in power output of a thermoelectric device in comparison to a device made from the previous best material Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. The n-type material used to make the unicouple device is the best reported nanostructured Hf0.25Zr0.75NiSn0.99Sb0.01 composition with the lowest hafnium (Hf) content. Both the p- and n-type nanostructured samples are prepared by ball milling the arc melted ingot and hot pressing the finely ground powders. Moreover, the raw material cost of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is more than six times lower compared to the cost of the previous best p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. This cost reduction is crucial for these materials to be used in large-scale quantities for vehicle and industrial waste heat recovery applications. DOE:DE-EE0004840.

  1. Electric field variations measured continuously in free air over a conductive thin zone in the tilted Lias-epsilon black shales near Osnabrück, Northwest Germany

    Science.gov (United States)

    Gurk, M.; Bosch, F. P.; Tougiannidis, N.

    2013-04-01

    Common studies on the static electric field distribution over a conductivity anomaly use the self-potential method. However, this method is time consuming and requires nonpolarizable electrodes to be placed in the ground. Moreover, the information gained by this method is restricted to the horizontal variations of the electric field. To overcome the limitation in the self-potential technique, we conducted a field experiment using a non conventional technique to assess the static electric field over a conductivity anomaly. We use two metallic potential probes arranged on an insulated boom with a separation of 126 cm. When placed into the electric field of the free air, a surface charge will be induced on each probe trying to equalize with the potential of the surrounding atmosphere. The use of a plasma source at both probes facilitated continuous and quicker measurement of the electric field in the air. The present study shows first experimental measurements with a modified potential probe technique (MPP) along a 600-meter-long transect to demonstrate the general feasibility of this method for studying the static electric field distribution over shallow conductivity anomalies. Field measurements were carried out on a test site on top of the Bramsche Massif near Osnabrück (Northwest Germany) to benefit from a variety of available near surface data over an almost vertical conductivity anomaly. High resolution self-potential data served in a numerical analysis to estimate the expected individual components of the electric field vector. During the experiment we found more anomalies in the vertical and horizontal components of the electric field than self-potential anomalies. These contrasting findings are successfully cross-validated with conventional near surface geophysical methods. Among these methods, we used self-potential, radiomagnetotelluric, electric resistivity tomography and induced polarization data to derive 2D conductivity models of the subsurface in

  2. Raman spectra of p-type transparent semiconducting Cr{sub 2}O{sub 3}:Mg

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, Karsten, E-mail: fleisck@tcd.ie; Caffrey, David; Farrell, Leo; Norton, Emma; Mullarkey, Daragh; Arca, Elisabetta; Shvets, Igor V.

    2015-11-02

    We present an analysis of the Raman spectra of p-type transparent conducting Cr{sub 2}O{sub 3}:Mg grown by various techniques including spray pyrolysis, pulsed laser deposition, molecular beam epitaxy and reactive magnetron sputtering. The best performing films show a distinct broad range Raman signature related to defect-induced vibrational modes not seen in stoichiometric, undoped material. Our comparative study demonstrates that Raman spectroscopy can quantify unwanted dopant clustering in the material at high Mg concentrations, while also being sensitive to the Mg incorporation site. By correlating the Raman signature to the electrical properties of the films, growth processes can be optimised to give the best conducting films and the local defect structure for effective p-type doping can be studied. - Highlights: • Mg doping in Cr{sub 2}O{sub 3} can lead to dopant clustering in MgCr{sub 2}O{sub 4} phase. • Post-annealing in oxygen can dissolve these clusters improving doping. • High oxygen pressures during growth can prevent dopant clustering. • Raman spectroscopy is a powerful tool to assist growth optimization in p-type oxides.

  3. Realization of stable p-type ZnO thin films using Li-N dual acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Rao, T. Prasada, E-mail: prasadview@gmail.com [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli- 620 015 (India); Kumar, M.C. Santhosh, E-mail: santhoshmc@nitt.edu [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli- 620 015 (India)

    2011-09-01

    Highlights: > We have presented a promising Li-N dual acceptor doping method to realize p-type ZnO films via spray pyrolysis. > The influence of concentration of Li-N on the structural, electrical, and optical properties of p-type ZnO:(Li, N) films were investigated in detail. > It is found that (Li, N):ZnO films deposited on glass substrate show the preferential orientation of (002) plane. > The Hall Effect measurements exhibited p-type behaviour on (Li, N):ZnO thin films and the stability of the samples were verified by aging studies. - Abstract: Lithium and nitrogen dual acceptors-doped p-type ZnO thin films have been prepared using spray pyrolysis technique. The influence of dual acceptor (Li, N) doping on the structural, electrical, and optical properties of (Li, N):ZnO films are investigated in detail. The (Li, N):ZnO films exhibit good crystallinity with a preferred c-axis orientation. From AFM studies, it is found that the surface roughness of the thin films increases with the increase of doping percentage. The Hall Effect measurements showed p-type conductivity. The Hall measurements have been performed periodically up to seven months and it is observed that the films show p-type conductivity throughout the period of observation. The samples with Li:N ratio of 8:8 mol% showed the lowest resistivity of 35.78 {Omega} cm, while sample with Li:N ratio of 6:6 mol% showed highest carrier concentration. The PL spectra of (Li, N):ZnO films show a strong UV emission at room temperature. Furthermore, PL spectra show low intensity in deep level transition, indicating a low density of native defects. This indicates that the formation of intrinsic defects is effectively suppressed by dual acceptor (Li, N) doping in ZnO thin films. The chemical bonding states of N and Li in the films were examined by XPS analysis.

  4. P-type InGaAsP coolers for integrated optic devices

    Science.gov (United States)

    Vashaee, Daryoosh; LaBounty, Christopher J.; Fang, Xiaofeng; Zeng, Gehong; Abraham, Patrick; Bowers, John E.; Shakouri, Ali

    2001-05-01

    Single stage thin film coolers based on thermoelectric and thermionic cooling in p-type InGaAsP superlattice structures have been fabricated. Devices with different sizes and at various ambient temperatures have been characterized. Experimental results showed 0.5 degree centigrade cooling below the ambient temperature at 25C. This cooling over 1 4mu2m thick superlattice barrier corresponds to cooling power densities on the order of 200 W/cm2. The device cools by a factor of two better at higher temperatures (70C). This is due to the reduction of the superlattice thermal conductivity and the broadening of the electronic distribution function at higher temperatures. 150x150 micrometers 2 devices provide largest cooling at room temperature while the optimum device size shrinks as the temperature increases. Simulations results that take into account finite thermal resistance of the InP substrate, the effect of the contact resistance, heat generation in the wire-bonds and metallic pads on top of the device predict accurately the optimum cooling of these micro refrigerators. By eliminating the major parasitic sources of heating (Joule heating in the substrate, heat conduction through the side contact and reducing the contact resistance to 5x7-7 ohm-cm2) simulations show that, ultimately, one can achieve 15 degree(s)C cooling (10's of kW/cm2 cooling power) with single stage p-InGaAsP thin film coolers.

  5. Enhanced thermoelectric figure of merit of p-type half-Heuslers.

    Science.gov (United States)

    Yan, Xiao; Joshi, Giri; Liu, Weishu; Lan, Yucheng; Wang, Hui; Lee, Sangyeop; Simonson, J W; Poon, S J; Tritt, T M; Chen, Gang; Ren, Z F

    2011-02-01

    Half-Heuslers would be important thermoelectric materials due to their high temperature stability and abundance if their dimensionless thermoelectric figure of merit (ZT) could be made high enough. The highest peak ZT of a p-type half-Heusler has been so far reported about 0.5 due to the high thermal conductivity. Through a nanocomposite approach using ball milling and hot pressing, we have achieved a peak ZT of 0.8 at 700 °C, which is about 60% higher than the best reported 0.5 and might be good enough for consideration for waste heat recovery in car exhaust systems. The improvement comes from a simultaneous increase in Seebeck coefficient and a significant decrease in thermal conductivity due to nanostructures. The samples were made by first forming alloyed ingots using arc melting and then creating nanopowders by ball milling the ingots and finally obtaining dense bulk by hot pressing. Further improvement in ZT is expected when average grain sizes are made smaller than 100 nm.

  6. P-type polymer-based Ag2S atomic switch for “tug of war” operation

    Science.gov (United States)

    Lutz, Carolin; Hasegawa, Tsuyoshi; Tsuchiya, Takashi; Adelsberger, Christoph; Hayakawa, Ryoma; Chikyow, Toyohiro

    2017-06-01

    The Ag2S gap-type atomic switch based “tug of war” device is a promising element for building a new type of CMOS free neuromorphic computer-hardware. Since Ag+ cations are reduced during operation of the device, it was thought that the gap-material should be a n-type polymer. In this study, we revealed that the polymer bithiophene-oligoethyleneoxide (BTOE) doped poly(ethylene oxide) (PEO), which was used as gap-material in the first demonstration of the “tug of war”, is a p-type polymer. For this we used impedance spectroscopy and transistor measurements. We elaborate on how the electrochemical processes in the “tug of war” devices could be explained in the case of p-type conductive gap-materials.

  7. Optical and Electrical Effects of p-type μc-SiOx:H in Thin-Film Silicon Solar Cells on Various Front Textures

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    2014-01-01

    Full Text Available p-type hydrogenated microcrystalline silicon oxide (µc-SiOx:H was developed and implemented as a contact layer in hydrogenated amorphous silicon (a-Si:H single junction solar cells. Higher transparency, sufficient electrical conductivity, low ohmic contact to sputtered ZnO:Al, and tunable refractive index make p-type µc-SiOx:H a promising alternative to the commonly used p-type hydrogenated microcrystalline silicon (µc-Si:H contact layers. In this work, p-type µc-SiOx:H layers were fabricated with a conductivity of up to 10−2 S/cm and a Raman crystallinity of above 60%. Furthermore, we present p-type µc-SiOx:H films with a broad range of optical properties (2.1 eV < band gap E04<2.8 eV and 1.6 < refractive index n<2.6. These properties can be tuned by adapting deposition parameters, for example, the CO2/SiH4 deposition gas ratio. A conversion efficiency improvement of a-Si:H solar cells is achieved by applying p-type µc-SiOx:H contact layer compared to the standard p-type µc-Si:H contact layer. As another aspect, the influence of the front side texture on a-Si:H p-i-n solar cells with different p-type contact layers, µc-Si:H and µc-SiOx:H, is investigated. Furthermore, we discuss the correlation between the decrease of Voc and the cell surface area derived from AFM measurements.

  8. A novel mechanism of P-type ATPase autoinhibition involving both termini of the protein

    DEFF Research Database (Denmark)

    Ekberg, Kira; Palmgren, Michael; Veierskov, Bjarke;

    2010-01-01

    The activity of many P-type ATPases is found to be regulated by interacting proteins or autoinhibitory elements located in N- or C-terminal extensions. An extended C terminus of fungal and plant P-type plasma membrane H+-ATPases has long been recognized to be part of a regulatory apparatus...

  9. Demethoxycurcumin is a potent inhibitor of P-type ATPases from diverse kingdoms of life

    DEFF Research Database (Denmark)

    Dao, Trong Tuan; Sehgal, Pankaj; Thanh Tung, Truong;

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used ...

  10. Application of neutron transmutation doping method to initially p-type silicon material.

    Science.gov (United States)

    Kim, Myong-Seop; Kang, Ki-Doo; Park, Sang-Jun

    2009-01-01

    The neutron transmutation doping (NTD) method was applied to the initially p-type silicon in order to extend the NTD applications at HANARO. The relationship between the irradiation neutron fluence and the final resistivity of the initially p-type silicon material was investigated. The proportional constant between the neutron fluence and the resistivity was determined to be 2.3473x10(19)nOmegacm(-1). The deviation of the final resistivity from the target for almost all the irradiation results of the initially p-type silicon ingots was at a range from -5% to 2%. In addition, the burn-up effect of the boron impurities, the residual (32)P activity and the effect of the compensation characteristics for the initially p-type silicon were studied. Conclusively, the practical methodology to perform the neutron transmutation doping of the initially p-type silicon ingot was established.

  11. Continuous tidal streamflow, water level, and specific conductance data for Union Creek and the Little Back, Middle, and Front Rivers, Savannah River Estuary, November 2008 to March 2009

    Science.gov (United States)

    Lanier, Timothy H.; Conrads, Paul A.

    2010-01-01

    In the Water Resource Development Act of 1999, the U.S. Congress authorized the deepening of the Savannah Harbor. Additional studies were then identified by the Georgia Ports Authority and other local and regional stakeholders to determine and fully describe the potential environmental effects of deepening the channel. One need that was identified was the validation of a three-dimensional hydrodynamic model developed to evaluate mitigation scenarios for a potential harbor deepening and the effects on the Savannah River estuary. The streamflow in the estuary is very complex due to reversing tidal flows, interconnections of streams and tidal creeks, and the daily flooding and draining of the marshes. The model was calibrated using very limited streamflow data and no continuous streamflow measurements. To better characterize the streamflow dynamics and mass transport of the estuary, two index-velocity sites were instrumented with continuous acoustic velocity, water level, and specific conductance sensors on the Little Back and Middle Rivers for the 5-month period of November 2008 through March 2009. During the same period, a third acoustic velocity meter was installed on the Front River just downstream from U.S. Geological Survey streamgaging station 02198920 (Savannah River at GA 25, at Port Wentworth, Georgia) where water level and specific conductance data were being collected. A fourth index-velocity site was instrumented with continuous acoustic velocity, water level, and specific conductance sensors on Union Creek for a 2-month period starting in November 2008. In addition to monitoring the tidal cycles, streamflow measurements were made at the four index-velocity sites to develop ratings to compute continuous discharge for each site. The maximum flood (incoming) and ebb (outgoing) tides measured on Little Back River were –4,570 and 7,990 cubic feet per second, respectively. On Middle River, the maximum flood and ebb tides measured were –9,630 and 13

  12. Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source

    Science.gov (United States)

    Wells, R. P.; Ghiorso, W.; Staples, J.; Huang, T. M.; Sannibale, F.; Kramasz, T. D.

    2016-02-01

    A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

  13. Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source.

    Science.gov (United States)

    Wells, R P; Ghiorso, W; Staples, J; Huang, T M; Sannibale, F; Kramasz, T D

    2016-02-01

    A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

  14. Porous silicon damage enhanced phosphorus and aluminium gettering of p-type Czochralski silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hassen, M. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia); Ben Jaballah, A. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia)]. E-mail: gadour2003@yahoo.fr; Hajji, M. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia); Rahmouni, H. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Faculte des Sciences de Monastir, Rue de Kairouan, 5000 Monastir (Tunisia); Selmi, A. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Faculte des Sciences de Monastir, Rue de Kairouan, 5000 Monastir (Tunisia); Ezzaouia, H. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia)

    2005-12-05

    In this work, porous silicon damage (PSD) is presented as a simple sequence for efficient external purification techniques. The method consists of using thin nanoporous p-type silicon on both sides of the silicon substrates with randomly hemispherical voids. Then, two main sample types are processed. In the first type, thin aluminium layers ({>=}1 {mu}m) are thermally evaporated followed by photo-thermal annealing treatments in N{sub 2} atmosphere at one of several temperatures ranging between 600 and 800 deg. C. In the second type, phosphorus is continually diffused in N{sub 2}/O{sub 2} ambient in a solid phase from POCl{sub 3} solution during heating at one of several temperatures ranging between 750 and 1000 deg. C for 1 h. Hall Effect and Van Der Pauw methods prove the existence of an optimum temperature in the case of phosphorus gettering at 900 deg. C yielding a Hall mobility of about 982 cm{sup 2} V{sup -1} s{sup -1}. However, in the case of aluminium gettering, there is no gettering limit in the as mentioned temperature range. Metal/Si Schottky diodes are elaborated to clarify these improvements. In this study, we demonstrate that enhanced metal solubility model cannot explain the gettering effect. The solid solubility of aluminium is higher than that of P atoms in silicon; however, the device yield confirms the effectiveness of phosphorus as compared to aluminium.

  15. Continuous On-Chip Cell Separation Based on Conductivity-Induced Dielectrophoresis with 3D Self-Assembled Ionic Liquid Electrodes.

    Science.gov (United States)

    Sun, Mingrui; Agarwal, Pranay; Zhao, Shuting; Zhao, Yi; Lu, Xiongbin; He, Xiaoming

    2016-08-16

    Dielectrophoresis (DEP) has been widely explored to separate cells for various applications. However, existing DEP devices are limited by the high cost associated with the use of noble metal electrodes, the need of high-voltage electric field, and/or discontinuous separation (particularly for devices without metal electrodes). We developed a DEP device with liquid electrodes, which can be used to continuously separate different types of cells or particles based on positive DEP. The device is made of polydimethylsiloxane (PDMS), and ionic liquid is used to form the liquid electrodes, which has the advantages of low cost and easy fabrication. Moreover, the conductivity gradient is utilized to achieve the DEP-based on-chip cell separation. The device was used to separate polystyrene microbeads and PC-3 human prostate cancer cells with 94.7 and 1.2% of the cells and microbeads being deflected, respectively. This device is also capable of separating live and dead PC-3 cancer cells with 89.8 and 13.2% of the live and dead cells being deflected, respectively. Moreover, MDA-MB-231 human breast cancer cells could be separated from human adipose-derived stem cells (ADSCs) using this device with high purity (81.8 and 82.5% for the ADSCs and MDA-MB-231 cells, respectively). Our data suggest the great potential of cell separation based on conductivity-induced DEP using affordable microfluidic devices with easy operation.

  16. Correlation Between the Raman Crystallinity of p-Type Micro-Crystalline Silicon Layer and Open Circuit Voltage of n-i-p Solar Cells.

    Science.gov (United States)

    Jung, Junhee; Kim, Sunbo; Park, Jinjoo; Shin, Chonghoon; Pham, Duy Phong; Kim, Jiwoong; Chung, Sungyoun; Lee, Youngseok; Yi, Junsin

    2015-10-01

    This article mainly discusses the difference between p-i-n and n-i-p type solar cells. Their structural difference has an effect on cell performance, such as open circuit voltage and fill factor. Although the deposition conditions are the same for both p-i-n and n-i-p cases, the substrate layers for depositing p-type microcrystalline silicon layers differ. In n-i-p cells, the substrate layer is p-type amorphous silicon oxide layer; whereas, in p-i-n cells, the substrate layer is ZnO:Al. The interfacial change leads to a 12% difference in the crystallinity of the p-type microcrystalline silicon layers. When the p-type microcrystalline silicon layer's crystallinity was not sufficient to activate an internal electric field, the open circuit voltage and fill factor decreased 0.075 V and 7.36%, respectively. We analyzed this problem by comparing the Raman spectra, electrical conductivity, activation energy and solar cell performance. By adjusting the thickness of the p-type microcrystalline silicon layer, we increased the open circuit voltage of the n-i-p cell from 0.835 to 0.91 V.

  17. Effect of Y (Yttrium) Filling Fraction on Thermoelectric Properties of p-type Yy Fex Co4-x Sb12

    Institute of Scientific and Technical Information of China (English)

    TANG Xinfeng; SONG Bo; ZHANG Qingjie

    2006-01-01

    Yttrium-filled skutterndites YyFex Co4-x Sb12 ( y= 0-0.40) were syrthesized. The effect of Y filling fraction on thermoelectric properties of YyFexCo4-xSb12 was investigated. All samples showed p-type conduct. The electrical conductivity decreased with increasing filling fraction y . The Seebeck coefficient increased with increasing temperature. The lattice thermal conductivity decreased with increasing filling fraction y and showed the minimum value at a certain filling fraction y = 0.3. The effect of different filling atoms M( M: Ba, Ce, Y) on the lattice thermal conductivity of MyFex Co4- x Sb12 was discussed. The maximum ZT value of 0.7 was obtained for Y0.08 Fe0.7 Co3.3 Sb12 at 750 K.

  18. High-throughput search of ternary chalcogenides for p-type transparent electrodes

    Science.gov (United States)

    Shi, Jingming; Cerqueira, Tiago F. T.; Cui, Wenwen; Nogueira, Fernando; Botti, Silvana; Marques, Miguel A. L.

    2017-01-01

    Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes. PMID:28266587

  19. High-throughput search of ternary chalcogenides for p-type transparent electrodes

    Science.gov (United States)

    Shi, Jingming; Cerqueira, Tiago F. T.; Cui, Wenwen; Nogueira, Fernando; Botti, Silvana; Marques, Miguel A. L.

    2017-03-01

    Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes.

  20. Compensation of native donor doping in ScN: Carrier concentration control and p-type ScN

    Science.gov (United States)

    Saha, Bivas; Garbrecht, Magnus; Perez-Taborda, Jaime A.; Fawey, Mohammed H.; Koh, Yee Rui; Shakouri, Ali; Martin-Gonzalez, Marisol; Hultman, Lars; Sands, Timothy D.

    2017-06-01

    Scandium nitride (ScN) is an emerging indirect bandgap rocksalt semiconductor that has attracted significant attention in recent years for its potential applications in thermoelectric energy conversion devices, as a semiconducting component in epitaxial metal/semiconductor superlattices and as a substrate material for high quality GaN growth. Due to the presence of oxygen impurities and native defects such as nitrogen vacancies, sputter-deposited ScN thin-films are highly degenerate n-type semiconductors with carrier concentrations in the (1-6) × 1020 cm-3 range. In this letter, we show that magnesium nitride (MgxNy) acts as an efficient hole dopant in ScN and reduces the n-type carrier concentration, turning ScN into a p-type semiconductor at high doping levels. Employing a combination of high-resolution X-ray diffraction, transmission electron microscopy, and room temperature optical and temperature dependent electrical measurements, we demonstrate that p-type Sc1-xMgxN thin-film alloys (a) are substitutional solid solutions without MgxNy precipitation, phase segregation, or secondary phase formation within the studied compositional region, (b) exhibit a maximum hole-concentration of 2.2 × 1020 cm-3 and a hole mobility of 21 cm2/Vs, (c) do not show any defect states inside the direct gap of ScN, thus retaining their basic electronic structure, and (d) exhibit alloy scattering dominating hole conduction at high temperatures. These results demonstrate MgxNy doped p-type ScN and compare well with our previous reports on p-type ScN with manganese nitride (MnxNy) doping.

  1. Thermal effect mechanism of magnetoresistance in p-type diamond films

    Institute of Scientific and Technical Information of China (English)

    Qin Guo-Ping; Kong Chun-Yang; Ruan Hai-Bo; Huang Gui-Juan; Cui Yu-Ting; Fang Liang

    2010-01-01

    Based on the analysis and the discussion of the influence of thermal ionization energy and various scatterings on magnetoresistance(MR) of p-type diamond films, a revised model of valence band split-off over temperature is put forward, and a corresponding calculation formula is given for the MR of p-type diamond films (Corbino discs). It is shown that the theoretical calculation that the MR of diamond films changes with temperature is consistent with the experiment. The influence of Fermi energy level on MR of diamond films is discussed. Additionally, the thermal effect mechanism of MR in p-type diamond films is also explored.

  2. Characterization of plasma etching damage on p -type GaN using Schottky diodes

    OpenAIRE

    2008-01-01

    The plasma etching damage in p-type GaN has been characterized. From current-voltage and capacitance-voltage characteristics of Schottky diodes, it was revealed that inductively coupled plasma (ICP) etching causes an increase in series resistance of the Schottky diodes and compensation of acceptors in p-type GaN. We investigated deep levels near the valence band of p-type GaN using current deep level transient spectroscopy (DLTS), and no deep level originating from the ICP etching damage was ...

  3. A Search of Low-Mass WIMPs with p-type Point Contact Germanium Detector in the CDEX-1 Experiment

    CERN Document Server

    Zhao, W; Kang, K J; Cheng, J P; Li, Y J; Wong, H T; Lin, S T; Chang, J P; Chen, J H; Chen, Q H; Chen, Y H; Deng, Z; Du, Q; Gong, H; Hao, X Q; He, H J; He, Q J; Huang, H X; Huang, T R; Jiang, H; Li, H B; Li, J; Li, J M; Li, X; Li, X Y; Li, Y L; Lin, F K; Liu, S K; Lü, L C; Ma, H; Ma, J L; Mao, S J; Qin, J Q; Ren, J; Ruan, X C; Sharma, V; Shen, M B; Singh, L; Singh, M K; Soma, A K; Su, J; Tang, C J; Wang, J M; Wang, L; Wang, Q; Wu, S Y; Wu, Y C; Xianyu, Z Z; Xiao, R Q; Xing, H Y; Xu, F Z; Xu, Y; Xu, X J; Xue, T; Yang, L T; Yang, S W; Yi, N; Yu, C X; Yu, H; Yu, X Z; Zeng, M; Zeng, X H; Zeng, Z; Zhang, L; Zhang, Y H; Zhao, M G; Zhou, Z Y; Zhu, J J; Zhu, W B; Zhu, X Z; Zhu, Z H

    2016-01-01

    The CDEX-1 experiment conducted a search of low-mass (< 10 GeV/c2) Weakly Interacting Massive Particles (WIMPs) dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware set-up, detector characterization, data acquisition and analysis procedures of this experiment. No excess of unidentified events are observed after subtraction of known background. Using 335.6 kg-days of data, exclusion constraints on the WIMP-nucleon spin-independent and spin-dependent couplings are derived.

  4. Origin of the p-type character of AuCl3 functionalized carbon nanotubes

    KAUST Repository

    Murat, Altynbek

    2014-02-13

    The microscopic origin of the p-type character of AuCl3 functionalized carbon nanotubes (CNTs) is investigated using first-principles self-interaction corrected density functional theory (DFT). Recent DFT calculations suggest that the p-type character of AuCl3 functionalized CNTs is due to the Cl atoms adsorbed on the CNTs. We test this hypothesis and show that adsorbed Cl atoms only lead to a p-type character for very specific concentrations and arrangements of the Cl atoms, which furthermore are not the lowest energy configurations. We therefore investigate alternative mechanisms and conclude that the p-type character is due to the adsorption of AuCl4 molecules. The unraveling of the exact nature of the p-doping adsorbates is a key step for further development of AuCl3 functionalized CNTs in water sensor applications. © 2014 American Chemical Society.

  5. Hot-wire chemical vapor deposition prepared aluminum doped p-type microcrystalline silicon carbide window layers for thin film silicon solar cells

    Science.gov (United States)

    Chen, Tao; Köhler, Florian; Heidt, Anna; Carius, Reinhard; Finger, Friedhelm

    2014-01-01

    Al-doped p-type microcrystalline silicon carbide (µc-SiC:H) thin films were deposited by hot-wire chemical vapor deposition at substrate temperatures below 400 °C. Monomethylsilane (MMS) highly diluted in hydrogen was used as the SiC source in favor of SiC deposition in a stoichiometric form. Aluminum (Al) introduced from trimethylaluminum (TMAl) was used as the p-type dopant. The material property of Al-doped p-type µc-SiC:H thin films deposited with different deposition pressure and filament temperature was investigated in this work. Such µc-SiC:H material is of mainly cubic (3C) SiC polytype. For certain conditions, like high deposition pressure and high filament temperature, additional hexagonal phase and/or stacking faults can be observed. P-type µc-SiC:H thin films with optical band gap E04 ranging from 2.0 to 2.8 eV and dark conductivity ranging from 10-5 to 0.1 S/cm can be prepared. Such transparent and conductive p-type µc-SiC:H thin films were applied in thin film silicon solar cells as the window layer, resulting in an improved quantum efficiency at wavelengths below 480 nm.

  6. Origin and evolution of metal P-type ATPases in Plantae (Archaeplastida)

    OpenAIRE

    2014-01-01

    Metal ATPases are a subfamily of P-type ATPases involved in the transport of metal cations across biological membranes. They all share an architecture featuring eight transmembrane domains in pairs of two and are found in prokaryotes as well as in a variety of Eukaryotes. In Arabidopsis thaliana, eight metal P-type ATPases have been described, four being specific to copper transport and four displaying a broader metal specificity, including zinc, cadmium and possibly copper and calcium. So fa...

  7. Groundwater discharge to wetlands driven by storm and flood events: Quantification using continuous Radon-222 and electrical conductivity measurements and dynamic mass-balance modelling

    Science.gov (United States)

    Gilfedder, B. S.; Frei, S.; Hofmann, H.; Cartwright, I.

    2015-09-01

    The dynamic response of groundwater discharge to external influences such as rainfall is an often neglected part of water and solute balances in wetlands. Here we develop a new field platform for long-term continuous 222Rn and electrical conductivity (EC) measurements at Sale Wetland, Australia to study the response of groundwater discharge to storm and flood events. The field measurements, combined with dynamic mass-balance modelling, demonstrate that the groundwater flux can increase from 3 to ∼20 mm d-1 following storms and up to 5 mm d-1 on the receding limb of floods. The groundwater pulses are likely produced by activation of local groundwater flow paths by water ponding on the surrounding flood plains. While 222Rn is a sensitive tracer for quantifying transient groundwater discharge, the mass-balance used to estimate fluxes is sensitive to parameterisation of gas exchange (k) with the atmosphere. Comparison of six equations for calculating k showed that, based on parameterisation of k alone, the groundwater flux estimate could vary by 58%. This work shows that neglecting transient processes will lead to errors in water and solute flux estimates based on infrequent point measurements. This could be particularly important for surface waters connected to contaminated or saline groundwater systems.

  8. Photoelectrochemical hydrogen-evolution over p-type chalcopyrite CuInSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Djellal, L. [Laboratoire des Solutions Solides, Faculte de Physique, (USTHB) BP 32 El Alia 16111, Algiers (Algeria); Omeiri, S.; Bouguelia, A. [Laboratoire de Stockage et de Valorisation des Energies Renouvelables, Faculte de Chimie, (USTHB) BP 32 El Alia 16111, Algiers (Algeria); Trari, M. [Laboratoire de Stockage et de Valorisation des Energies Renouvelables, Faculte de Chimie, (USTHB) BP 32 El Alia 16111, Algiers (Algeria)], E-mail: mtrari@caramail.com

    2009-05-12

    Photocatalytic H{sub 2}-production has been realized over active CuInSe{sub 2}, synthesized by the fusion technique. The material crystallizes in the chalcopyrite structure and exhibits p-type conductivity ascribed to copper deficiency. An optical gap of 0.95 eV was determined from the reflectance diffuse spectrum. The electrical conductivity follows an Arrhenius-type law with activation energy of 23 meV in conformity with polaron hopping. The slope and the intercept of the Mott-Schottky plot gave a holes density N{sub A} of 5.9 x 10{sup 18} cm{sup -3} and a flat band potential of -0.36V{sub SCE}, in perfect agreement with the photo-onset potential V{sub on} (-0.35V{sub SCE}). Hence, the conduction band, located at -1.29V{sub SCE}, allows a spontaneous H{sub 2} liberation upon visible light. In aqueous solutions, the material is stabilized by hole consumption involving X{sup 2-} species (=S{sup 2-} and SO{sub 3}{sup 2-}). H{sub 2} formation would become thermodynamically easy in alkaline media and the best photoactivity was obtained in thiosulfate electrolyte (10{sup -2} M S{sub 2}O{sub 3}{sup 2-}, 0.5 M KOH) with an evolution rate of 0.009 ml mg{sup -1} h{sup -1}. The light induced electron transfer through the interface involves two steps mechanism where S{sub 2}O{sub 3}{sup 2-} is oxidized to SO{sub 3}{sup 2-} and SO{sub 4}{sup 2-} by successive reactions. Such results are corroborated by the semi logarithmic plots and photocurrent-photopotential characteristics. The influence of pH was studied with S{sub 2}O{sub 3}{sup 2-} The tendency towards saturation for prolonged irradiation is attributed to competitive reductions of the end products S{sub n}{sup 2-} and S{sub 2}O{sub 6}{sup 2-} with water and to the yellow color of polysulfide S{sub n}{sup 2-}.

  9. Nanostructured p-Type Semiconductor Electrodes and Photoelectrochemistry of Their Reduction Processes

    Directory of Open Access Journals (Sweden)

    Matteo Bonomo

    2016-05-01

    Full Text Available This review reports the properties of p-type semiconductors with nanostructured features employed as photocathodes in photoelectrochemical cells (PECs. Light absorption is crucial for the activation of the reduction processes occurring at the p-type electrode either in the pristine or in a modified/sensitized state. Beside thermodynamics, the kinetics of the electron transfer (ET process from photocathode to a redox shuttle in the oxidized form are also crucial since the flow of electrons will take place correctly if the ET rate will overcome that one of recombination and trapping events which impede the charge separation produced by the absorption of light. Depending on the nature of the chromophore, i.e., if the semiconductor itself or the chemisorbed dye-sensitizer, different energy levels will be involved in the cathodic ET process. An analysis of the general properties and requirements of electrodic materials of p-type for being efficient photoelectrocatalysts of reduction processes in dye-sensitized solar cells (DSC will be given. The working principle of p-type DSCs will be described and extended to other p-type PECs conceived and developed for the conversion of the solar radiation into chemical products of energetic/chemical interest like non fossil fuels or derivatives of carbon dioxide.

  10. Recent Developments in p-Type Oxide Semiconductor Materials and Devices

    KAUST Repository

    Wang, Zhenwei

    2016-02-16

    The development of transparent p-type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p-type oxide semiconductors are reviewed, including ternary Cu-bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence-band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off-state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p-type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p-type oxides still lag in performance behind their n-type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p-type oxide semiconductors are presented.

  11. Chemical-free n-type and p-type multilayer-graphene transistors

    Energy Technology Data Exchange (ETDEWEB)

    Dissanayake, D. M. N. M., E-mail: nandithad@voxtel-inc.com [Voxtel Inc, Lockey Laboratories, University of Oregon, Eugene Oregon 97402 (United States); Eisaman, M. D. [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Department of Electrical and Computer Engineering, Stony Brook University, Stony Brook, New York 11794 (United States); Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794 (United States)

    2016-08-01

    A single-step doping method to fabricate n- and p-type multilayer graphene (MG) top-gate field effect transistors (GFETs) is demonstrated. The transistors are fabricated on soda-lime glass substrates, with the n-type doping of MG caused by the sodium in the substrate without the addition of external chemicals. Placing a hydrogen silsesquioxane (HSQ) barrier layer between the MG and the substrate blocks the n-doping, resulting in p-type doping of the MG above regions patterned with HSQ. The HSQ is deposited in a single fabrication step using electron beam lithography, allowing the patterning of arbitrary sub-micron spatial patterns of n- and p-type doping. When a MG channel is deposited partially on the barrier and partially on the glass substrate, a p-type and n-type doping profile is created, which is used for fabricating complementary transistors pairs. Unlike chemically doped GFETs in which the external dopants are typically introduced from the top, these substrate doped GFETs allow for a top gate which gives a stronger electrostatic coupling to the channel, reducing the operating gate bias. Overall, this method enables scalable fabrication of n- and p-type complementary top-gated GFETs with high spatial resolution for graphene microelectronic applications.

  12. Recent Developments in p-Type Oxide Semiconductor Materials and Devices.

    Science.gov (United States)

    Wang, Zhenwei; Nayak, Pradipta K; Caraveo-Frescas, Jesus A; Alshareef, Husam N

    2016-05-01

    The development of transparent p-type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p-type oxide semiconductors are reviewed, including ternary Cu-bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence-band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off-state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p-type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p-type oxides still lag in performance behind their n-type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p-type oxide semiconductors are presented.

  13. Reliability tests of electroless barriers against copper diffusion under bias-temperature stress with n- and p-type substrates

    Science.gov (United States)

    Ueno, Kazuyoshi; Fujishima, Shota; Yamashita, Makoto; Mitsumori, Akiyoshi

    2016-05-01

    To investigate the similarity and difference of substrate conduction type in the time-dependent dielectric breakdown (TDDB) tests for the barrier integrity against Cu diffusion under bias-temperature stress (BTS), the TDDB reliability of electroless NiB and CoWP/NiB was determined by metal oxide semiconductor (MOS) structures on n-type Si (n-Si) substrates, and the test results were compared with those using p-type Si (p-Si) substrates. The TDDB results and mechanism were observed to be qualitatively the same as Cu diffusion for both conduction types. However, the TDDB lifetime using p-Si was found to be potentially shorter because of the reverse bias conditions than that using n-Si under the forward bias conditions.

  14. Identifying individual n- and p-type ZnO nanowires by the output voltage sign of piezoelectric nanogenerator

    Energy Technology Data Exchange (ETDEWEB)

    Lin, S S; Song, J H; Wang, Z L [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Lu, Y F, E-mail: zlwang@gatech.ed [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027 (China)

    2009-09-09

    Based on a comparative study between the piezoelectric outputs of n-type nanowires (NWs) and n-core/p-shell NWs along with the previous study (Lu et al 2009 Nano. Lett. 9 1223), we demonstrate a one-step technique for identifying the conductivity type of individual ZnO nanowires (NWs) based on the output of a piezoelectric nanogenerator without destroying the sample. A negative piezoelectric output voltage indicates an NW is n-type and it appears after the tip scans across the center of the NW, while a positive output voltage reveals p-type conductivity and it appears before the tip scans across the central line of the NW. This atomic force microscopy based technique is reliable for statistically mapping the majority carrier type in ZnO NWs arrays. The technique may also be applied to other wurtzite semiconductors, such as GaN, CdS and ZnS.

  15. Identifying individual n- and p-type ZnO nanowires by the output voltage sign of piezoelectric nanogenerator

    KAUST Repository

    Lin, S S

    2009-08-18

    Based on a comparative study between the piezoelectric outputs of n-type nanowires (NWs) and n-core/p-shell NWs along with the previous study (Lu et al 2009 Nano. Lett. 9 1223), we demonstrate a one-step technique for identifying the conductivity type of individual ZnO nanowires (NWs) based on the output of a piezoelectric nanogenerator without destroying the sample. A negative piezoelectric output voltage indicates an NW is n-type and it appears after the tip scans across the center of the NW, while a positive output voltage reveals p-type conductivity and it appears before the tip scans across the central line of the NW. This atomic force microscopy based technique is reliable for statistically mapping the majority carrier type in ZnO NWs arrays. The technique may also be applied to other wurtzite semiconductors, such as GaN, CdS and ZnS. © 2009 IOP Publishing Ltd.

  16. High temperature thermoelectric properties of p-type skutterudites BaxYbyCo4-zFezSb12

    KAUST Repository

    Dong, Y.

    2012-01-01

    Several polycrystalline p-type skutterudites with compositions Ba xYb yCo 4-zFe zSb 12, with varying filler concentrations x and y, and z = 1 to 2, were synthesized by reacting the constituents and subsequent solid state annealing, followed by densification by hot-pressing. Their thermoelectric properties were evaluated from 300 to 820 K. The Yb filling fraction increased with Fe content while the amount of Fe substitution had little influence on the Ba filling fraction. High purity specimens were obtained when the Fe content was low. Bipolar conduction contributed to the thermal conductivity at elevated temperatures. A maximum ZT value of 0.7 was obtained at 750 K for the specimen with the highest Fe content and filling fraction. The potential for thermoelectric applications is also discussed. © 2012 American Institute of Physics.

  17. Transparent p-type SnO nanowires with unprecedented hole mobility among oxide semiconductors

    KAUST Repository

    Caraveo-Frescas, J. A.

    2013-11-25

    p-type tin monoxide (SnO) nanowire field-effect transistors with stable enhancement mode behavior and record performance are demonstrated at 160 °C. The nanowire transistors exhibit the highest field-effect hole mobility (10.83 cm2 V−1 s−1) of any p-type oxide semiconductor processed at similar temperature. Compared to thin film transistors, the SnO nanowire transistors exhibit five times higher mobility and one order of magnitude lower subthreshold swing. The SnO nanowire transistors show three times lower threshold voltages (−1 V) than the best reported SnO thin film transistors and fifteen times smaller than p-type Cu 2O nanowire transistors. Gate dielectric and process temperature are critical to achieving such performance.

  18. DyP-type peroxidases comprise a novel heme peroxidase family.

    Science.gov (United States)

    Sugano, Y

    2009-04-01

    Dye-decolorizing peroxidase (DyP) is produced by a basidiomycete (Thanatephorus cucumeris Dec 1) and is a member of a novel heme peroxidase family (DyP-type peroxidase family) that appears to be distinct from general peroxidases. Thus far, 80 putative members of this family have been registered in the PeroxiBase database (http://peroxibase.isbsib.ch/) and more than 400 homologous proteins have been detected via PSI-BLAST search. Although few studies have characterized the function and structure of these proteins, they appear to be bifunctional enzymes with hydrolase or oxygenase, as well as typical peroxidase activities. DyP-type peroxidase family suggests an ancient root compared with other general peroxidases because of their widespread distribution in the living world. In this review, firstly, an outline of the characteristics of DyP from T. cucumeris is presented and then interesting characteristics of the DyP-type peroxidase family are discussed.

  19. Demethoxycurcumin is a potent inhibitor of P-type ATPases from diverse kingdoms of life

    DEFF Research Database (Denmark)

    Dao, Trong Tuan; Sehgal, Pankaj; Thanh Tung, Truong;

    2016-01-01

    the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site......P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used...... as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among...

  20. A simple model to estimate the optimal doping of p - Type oxide superconductors

    Directory of Open Access Journals (Sweden)

    Adir Moysés Luiz

    2008-12-01

    Full Text Available Oxygen doping of superconductors is discussed. Doping high-Tc superconductors with oxygen seems to be more efficient than other doping procedures. Using the assumption of double valence fluctuations, we present a simple model to estimate the optimal doping of p-type oxide superconductors. The experimental values of oxygen content for optimal doping of the most important p-type oxide superconductors can be accounted for adequately using this simple model. We expect that our simple model will encourage further experimental and theoretical researches in superconducting materials.

  1. Dual ohmic contact to N- and P-type silicon carbide

    Science.gov (United States)

    Okojie, Robert S. (Inventor)

    2013-01-01

    Simultaneous formation of electrical ohmic contacts to silicon carbide (SiC) semiconductor having donor and acceptor impurities (n- and p-type doping, respectively) is disclosed. The innovation provides for ohmic contacts formed on SiC layers having n- and p-doping at one process step during the fabrication of the semiconductor device. Further, the innovation provides a non-discriminatory, universal ohmic contact to both n- and p-type SiC, enhancing reliability of the specific contact resistivity when operated at temperatures in excess of 600.degree. C.

  2. High surface hole concentration p-type GaN using Mg implantation

    CERN Document Server

    Long Tao; Zhang Guo Yi

    2001-01-01

    Mg ions were implanted on Mg-doped GaN grown by metalorganic chemical vapor deposition (MOCVD). The p-type GaN was achieved with high hole concentration (8.28 x 10 sup 1 sup 7 cm sup - sup 3) conformed by Van derpauw Hall measurement after annealing at 800 degree C for 1 h. this is the first experimental report of Mg implantation on Mg-doped GaN and achieving p-type GaN with high surface hole concentration

  3. Effect of Ba Filling Fraction on Thermoelectric Properties of p-type BayFe1.6Co2.4Sb12

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Effects of Ba filling fraction on the thermoelectric properties of p-type filled skutterudite compounds BayFe1.6Co2.4Sb12(y=0-0.63) were investigated.BayFe1.6Co2.4Sb12 showed p-type conduction.The hall coefficient (RH) and seebeck coefficient(α) increased with increasing Ba filling fraction.But hole concentration (p) and electrical conductivity (σ) decreased.While Ba filling fraction was about 0.4,the lattice thermal conductivity (κL) reached the minimum value.The results show that effect of Ba rattling on phonon scattering is the strongest as Sb-icosahedron partial voids are filled by Ba.A maximum dimensionless thermoelectric figure of merit (ZT) value of 0.7 was obtained for Ba0.38Fe1.6Co2.4 Sb12 at 750K.

  4. Improving the radiation hardness properties of silicon detectors using oxygenated n-type and p-type silicon

    CERN Document Server

    Casse, G L; Hanlon, M

    2000-01-01

    The degradation of the electrical properties of silicon detectors exposed to 24 GeV/c protons were studied using pad diodes made from different silicon materials. Standard high-grade p-type and n-type substrates and oxygenated n-type substrates have been used. The diodes were studied in terms of reverse current (I/sub r/) and full depletion voltage (V/sub fd/) as a function of fluence. The oxygenated devices from different suppliers with a variety of starting materials and techniques, all show a consistent improvement of the degradation rate of V/sub fd/ and CCE compared to un- oxygenated substrate devices. Radiation damage of n-type detectors introduces stable defects acting as effective p-type doping and leads to the change of the conductivity type of the silicon bulk (type inversion) at a neutron equivalent fluence of a few 10/sup 13/ cm/sup -2/. The diode junction after inversion migrates from the original side to the back plane of the detector. The migration of the junction is avoided using silicon detec...

  5. The synthesis and characterization of Ag-N dual-doped p-type ZnO: experiment and theory.

    Science.gov (United States)

    Duan, Li; Wang, Pei; Yu, Xiaochen; Han, Xiao; Chen, Yongnan; Zhao, Peng; Li, Donglin; Yao, Ran

    2014-03-07

    Ag-N dual-doped ZnO films have been fabricated by a chemical bath deposition method. The p-type conductivity of the dual-doped ZnO:(Ag, N) is stable over a long period of time, and the hole concentration in the ZnO:(Ag, N) is much higher than that in mono-doped ZnO:Ag or ZnO:N. We found that this is because AgZn-NO complex acceptors can be formed in ZnO:(Ag, N). First-principles calculations show that the complex acceptors generate a fully occupied band above the valance band maximum, so the acceptor levels become shallower and the hole concentration is increased. Furthermore, the binding energy of the Ag-N complex in ZnO is negative, so ZnO:(Ag, N) can be stable. These results indicate that the Ag-N dual-doping may be expected to be a potential route to achieving high-quality p-type ZnO for use in a variety of devices.

  6. Relative Frequencies of G and P Types among Rotaviruses from Indian Diarrheic Cow and Buffalo Calves

    Science.gov (United States)

    Gulati, Baldev R.; Nakagomi, Osamu; Koshimura, Yumi; Nakagomi, Toyoko; Pandey, Ramayan

    1999-01-01

    While an increasing number of studies suggest that there is a high prevalence of rotaviruses with P8[11], a typical P type of bovine rotavirus (BRV), among human neonates or infants in India, no data are available on the distribution of G and P types of Indian BRVs. Thus, fecal specimens were collected from cow and buffalo calves under 1 month of age on organized dairy farms in India during the period between 1994 and 1997, and 36 rotavirus-positive specimens were used to determine the relative frequencies of the G and P types of Indian BRVs. As to the G type, G10 was predominant (83%), followed by G6 (6%). The majority (94%) of BRVs had P8[11], and only one isolate possessed P6[1]. The most common combination of G and P types was G10P8[11] (81%), followed by G6P6[1] (3%) and G6P8[11] (3%). The high prevalence of BRVs possessing P8[11] VP4s strongly supports the hypothesis that BRVs may cross the host species barrier and circulate among neonates in India. PMID:10325385

  7. Characterization of 3D-DDTC detectors on p-type substrates

    CERN Document Server

    Betta, G -F Dalla; Bosisio, Luciano; Darbo, Giovanni; Gabos, Paolo; Gemme, Claudia; Koehler, Michael; La Rosa, Alessandro; Parzefall, Ulrich; Pernegger, Heinz; Piemonte, Claudio; Povoli, Marco; Rachevskaia, Irina; Ronchin, Sabina; Wiik, Liv; Zoboli, Aanrea; Zorzi, Nicola

    2009-01-01

    We report on the electrical and functional characterization of 3D Double-side, Double-Type-Column (3D- DDTC) detectors fabricated on p-type substrates. Results relevant to detectors in the diode, strip and pixel configurations are presented, and demonstrate a clear improvement in the charge collection performance compared to the first prototypes of these detectors.

  8. Origin and evolution of metal p-Type ATPases in Plantae (Archaeplastida

    Directory of Open Access Journals (Sweden)

    Marc eHanikenne

    2014-01-01

    Full Text Available Metal ATPases are a subfamily of P-type ATPases involved in the transport of metal cations across biological membranes. They all share an architecture featuring eight transmembrane domains in pairs of two and are found in prokaryotes as well as in a variety of Eukaryotes. In Arabidopsis thaliana, eight metal P-type ATPases have been described, four being specific to copper transport and four displaying a broader metal specificity, including zinc, cadmium and possibly copper and calcium. So far, few efforts have been devoted to elucidating the origin and evolution of these proteins in Eukaryotes. In this work, we use large-scale phylogenetics to show that metal P-type ATPases form a homogenous group among P-type ATPases and that their specialisation into either monovalent (Cu or divalent (Zn, Cd… metal transport stems from a gene duplication that took place early in the evolution of Life. Then, we demonstrate that the four subgroups of plant metal ATPases all have a different evolutionary origin and a specific taxonomic distribution, only one tracing back to the cyanobacterial progenitor of the chloroplast. Finally, we examine the subsequent evolution of these proteins in green plants and conclude that the genes thoroughly characterised in model organisms are often the result of lineage-specific gene duplications, which calls for caution when attempting to infer function from sequence similarity alone in non-model organisms.

  9. A structural and functional perspective of DyP-type peroxidase family.

    Science.gov (United States)

    Yoshida, Toru; Sugano, Yasushi

    2015-05-15

    Dye-decolorizing peroxidase from the basidiomycete Bjerkandera adusta Dec 1 (DyP) is a heme peroxidase. This name reflects its ability to degrade several anthraquinone dyes. The substrate specificity, the amino acid sequence, and the tertiary structure of DyP are different from those of the other heme peroxidase (super)families. Therefore, many proteins showing the similar amino acid sequences to that of DyP are called DyP-type peroxidase which is a new family of heme peroxidase identified in 2007. In fact, all structures of this family show a similar structure fold. However, this family includes many proteins whose amino acid sequence identity to DyP is lower than 15% and/or whose catalytic efficiency (kcat/Km) is a few orders of magnitude less than that of DyP. A protein showing an activity different from peroxidase activity (dechelatase activity) has been also reported. In addition, the precise physiological roles of DyP-type peroxidases are unknown. These facts raise a question of whether calling this family DyP-type peroxidase is suitable. Here, we review the differences and similarities of structure and function among this family and propose the reasonable new classification of DyP-type peroxidase family, that is, class P, I and V. In this contribution, we discuss the adequacy of this family name.

  10. Lifetime and DLTS studies of interstitial Fe in p-type Si

    Energy Technology Data Exchange (ETDEWEB)

    Syre, M.; Holt, A. [Institute for Energy Technology (IFE), Solar Energy Department, P.O. Box 40, 2027 Kjeller (Norway); Monakov, E. [University of Oslo (UiO), Department of Physics, Blindern P.O. Box 1048, 0316 Oslo (Norway); Institute for Energy Technology (IFE), Solar Energy Department, P.O. Box 40, 2027 Kjeller (Norway); Svensson, B.G. [University of Oslo (UiO), Department of Physics, Blindern P.O. Box 1048, 0316 Oslo (Norway)

    2011-03-15

    Fe is one of the most prominent metallic impurities in solar-grade Si. In this work we have investigated the kinetics of in-diffusion and formation of the interstitial fraction (Fe{sub i}). P-type Cz-Si with a resistivity of 10 {omega}-cm has been intentionally contaminated with Fe by in-diffusion from a surface layer of FeCl{sub 3} at 700 C followed by cooling with a rate of {proportional_to} 3.3 K/s. The concentration of Fe{sub i} has been measured both by microwave photo conductance decay ({mu}-PCD) and deep level transient spectroscopy (DLTS). In the {mu}-PCD measurements, the Fe{sub i} concentration has been determined using the ef- fect of light-induced splitting of the iron-boron pairs (FeB), while in the DLTS measurements Fe{sub i} has been monitored by the donor electronic state at 0.43 eV above the valence band. We have observed a linear dependence between the minority carrier lifetime ({tau}) and the inverse Fe{sub i} concentration. This confirms Fe{sub i} as the dominating recombination centre. In the present investigations we use a material relevant for solar cells with a resistivity of 10 {omega}-cm. We have found that the concentration of interstitial iron decreases with increasing time for in-diffusion of Fe, provided identical cooling condition. This decreasing con- centration of Fe{sub i} is believed to be due to formation of more iron precipitates that serve as sinks for fast diffusing Fe{sub i}. A high temperature anneal at 1000 C for 1 minute followed by fast cooling ({proportional_to} 33 K/s) results in dissolution of the precipitates and freezing Fe into interstitial positions, where the concentration of Fe{sub i} increases with increasing in-diffusion time. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Investigations of nanoreactors on the basis of p-type porous silicon: Electron structure and phase composition

    Energy Technology Data Exchange (ETDEWEB)

    Lenshin, A.S. [Voronezh State University, Solid State Physics and Nanostructures Department, Universitetskaya pl. 1, Voronezh 394006 (Russian Federation); Kashkarov, V.M., E-mail: kash@phys.vsu.ru [Voronezh State University, Solid State Physics and Nanostructures Department, Universitetskaya pl. 1, Voronezh 394006 (Russian Federation); Spivak, Yu. M. [SPbGETU ' LETI' , Department of Microelectronics (Russian Federation); Moshnikov, V.A., E-mail: vamoshnikov@mail.ru [SPbGETU ' LETI' , Department of Microelectronics (Russian Federation)

    2012-08-15

    Investigations of the electron structure and phase composition of the surface layers in porous silicon with a developed system of nanopores were made with the use of ultrasoft X-ray spectroscopy and X-ray photoelectron spectroscopy. The samples of porous silicon were obtained on the substrates with p-type conductivity under different modes of electrochemical etching. Porous surface layer represents a system of weakly connected pores oriented mainly perpendicular to the surface of silicon wafer. The mean transverse pore dimension is of {approx}50 nm. Silicon dioxide and sub-oxide were found in porous layer. We assume that these phases cover pores surface thus providing a possibility of the use of the structures as nanoreactors. -- Highlights: Black-Right-Pointing-Pointer Nanoporous silicon layers were obtained. Black-Right-Pointing-Pointer A system of weakly connected pores was detected. Black-Right-Pointing-Pointer Electron structure and phase composition of the surface layers in porous silicon were investigated.

  12. Continuous right ventricular volumetry by fast-response thermodilution during right ventricular ischemia: head-to-head comparison with conductance catheter measurements.

    NARCIS (Netherlands)

    Hein, M.; Roehl, A.B.; Baumert, J.H.; Rossaint, R.; Steendijk, P.

    2009-01-01

    OBJECTIVE: To evaluate the accuracy of right ventricular ejection fraction and right ventricular end-diastolic volume obtained by volumetric pulmonary artery catheter, using the conductance catheter as reference method. DESIGN: Prospective, comparative study. SETTING: Research laboratory of a univer

  13. Continuous right ventricular volumetry by fast-response thermodilution during right ventricular ischemia: head-to-head comparison with conductance catheter measurements.

    NARCIS (Netherlands)

    Hein, M.; Roehl, A.B.; Baumert, J.H.; Rossaint, R.; Steendijk, P.

    2009-01-01

    OBJECTIVE: To evaluate the accuracy of right ventricular ejection fraction and right ventricular end-diastolic volume obtained by volumetric pulmonary artery catheter, using the conductance catheter as reference method. DESIGN: Prospective, comparative study. SETTING: Research laboratory of a

  14. CCE measurements and annealing studies on proton-irradiated p-type MCz silicon diodes

    CERN Document Server

    Hoedlmoser, H; Köhler, M; Nordlund, H

    2007-01-01

    Magnetic Czochralski (MCz) silicon has recently been investigated for the development of radiation tolerant detectors for future high-luminosity HEP experiments. A study of p-type MCz Silicon diodes irradiated with protons up to a fluence of has been performed by means of Charge Collection Efficiency (CCE) measurements as well as standard CV/IV characterizations. The changes of CCE, full depletion voltage and leakage current as a function of fluence are reported. A subsequent annealing study of the irradiated detectors shows an increase in effective doping concentration and a decrease in the leakage current, whereas the CCE remains basically unchanged. Two different series of detectors have been compared differing in the implantation dose of p-spray isolation as well as effective doping concentration (Neff) of the p-type bulk presumably due to a difference in thermal donor (TD) activation during processing. The series with the higher concentration of TDs shows a delayed reverse annealing of Neff after irradia...

  15. Fabrication of p-type lithium niobate crystals by molybdenum doping and polarization

    Science.gov (United States)

    Tian, Tian; Kong, Yongfa; Liu, Hongde; Liu, Shiguo; Li, Wei; Chen, Shaolin; Xu, Jiayue

    2017-06-01

    The lack of p-type lithium niobate limits it serving as an active material. A series of Mo-doped and pure congruent lithium niobate crystals were grown by Czochralski method under different polarization conditions. Their dominant carrier species were characterized by holographic experiment. The results showed dominant charge carrier species may be changed from electrons to holes when lithium niobate crystal was doped with Mo ions and polarized under the current of 70mA for 30 minutes. It indicated that p-type lithium niobate crystal could be fabricated by Mo-doping and suitably controlling the polarization condition. Mo-doped lithium niobate crystals can be a promising candidate for active components.

  16. Enhancement of p-type mobility in tin monoxide by native defects

    KAUST Repository

    Granato, D. B.

    2013-05-31

    Transparent p-type materials with good mobility are needed to build completely transparent p-n junctions. Tin monoxide (SnO) is a promising candidate. A recent study indicates great enhancement of the hole mobility of SnO grown in Sn-rich environment [E. Fortunato et al., Appl. Phys. Lett. 97, 052105 (2010)]. Because such an environment makes the formation of defects very likely, we study defect effects on the electronic structure to explain the increased mobility. We find that Sn interstitials and O vacancies modify the valence band, inducing higher contributions of the delocalized Sn 5p orbitals as compared to the localized O 2p orbitals, thus increasing the mobility. This mechanism of valence band modification paves the way to a systematic improvement of transparent p-type semiconductors.

  17. A Density Functional Theory Study of Doped Tin Monoxide as a Transparent p-type Semiconductor

    KAUST Repository

    Bianchi Granato, Danilo

    2012-05-01

    In the pursuit of enhancing the electronic properties of transparent p-type semiconductors, this work uses density functional theory to study the effects of doping tin monoxide with nitrogen, antimony, yttrium and lanthanum. An overview of the theoretical concepts and a detailed description of the methods employed are given, including a discussion about the correction scheme for charged defects proposed by Freysoldt and others [Freysoldt 2009]. Analysis of the formation energies of the defects points out that nitrogen substitutes an oxygen atom and does not provide charge carriers. On the other hand, antimony, yttrium, and lanthanum substitute a tin atom and donate n-type carriers. Study of the band structure and density of states indicates that yttrium and lanthanum improves the hole mobility. Present results are in good agreement with available experimental works and help to improve the understanding on how to engineer transparent p-type materials with higher hole mobilities.

  18. Efficiency Improvement of HIT Solar Cells on p-Type Si Wafers

    Directory of Open Access Journals (Sweden)

    Chun-You Wei

    2013-11-01

    Full Text Available Single crystal silicon solar cells are still predominant in the market due to the abundance of silicon on earth and their acceptable efficiency. Different solar-cell structures of single crystalline Si have been investigated to boost efficiency; the heterojunction with intrinsic thin layer (HIT structure is currently the leading technology. The record efficiency values of state-of-the art HIT solar cells have always been based on n-type single-crystalline Si wafers. Improving the efficiency of cells based on p-type single-crystalline Si wafers could provide broader options for the development of HIT solar cells. In this study, we varied the thickness of intrinsic hydrogenated amorphous Si layer to improve the efficiency of HIT solar cells on p-type Si wafers.

  19. Measurement of the dead layer thickness in a p-type point contact germanium detector

    Science.gov (United States)

    Jiang, Hao; Yue, Qian; Li, Yu-Lan; Kang, Ke-Jun; Li, Yuan-Jing; Li, Jin; Lin, Shin-Ted; Liu, Shu-Kui; Ma, Hao; Ma, Jing-Lu; Su, Jian; Tsz-King Wong, Henry; Yang, Li-Tao; Zhao, Wei; Zeng, Zhi

    2016-09-01

    A 994 g mass p-type PCGe detector has been deployed during the first phase of the China Dark matter EXperiment, aiming at direct searches for light weakly interacting massive particles. Measuring the thickness of the dead layer of a p-type germanium detector is an issue of major importance since it determines the fiducial mass of the detector. This work reports a method using an uncollimated 133Ba source to determine the dead layer thickness. The experimental design, data analysis and Monte Carlo simulation processes, as well as the statistical and systematic uncertainties are described. A dead layer thickness of 1.02 mm was obtained based on a comparison between the experimental data and the simulated results. Supported by National Natural Science Foundation of China (10935005, 10945002, 11275107, 11175099)

  20. Preparation and Photovoltaic Properties of p-Type Nano-ZnFe2O4

    Institute of Scientific and Technical Information of China (English)

    LI Zi-heng; ZOU Xu; LI Gen; ZOU Guang-tian

    2012-01-01

    p-Type nano-ZnFe2O4 semiconductors were gained by high-prssure treatment.Surface photovoltaic spectrum(SPS) and transient photovoltaic technology(TPV) were used for studying the photogenerated charge of nano-ZnFe2O4.Results show that the photovoltaic behavior of nano-ZnFe2O4 changed as the processing pressure increased.When the processing pressure was higher than 2 GPa,both SPS response interval and peak changed significantly.XPS results show that the non-lattice oxygen entered into the lattice and the content of lattice oxygen increased with the increase of processing pressure.The material changed from oxygen vacancy type to oxygen excess type and the photoelectric properties changed from n-type to p-type when the processing pressure is higher than 2GPa.

  1. In and out of the cation pumps: P-type ATPase structure revisited

    DEFF Research Database (Denmark)

    Bublitz, Maike; Poulsen, Hanne; Morth, Jens Preben

    2010-01-01

    Active transport across membranes is a crucial requirement for life. P-type ATPases build up electrochemical gradients at the expense of ATP by forming and splitting a covalent phosphoenzyme intermediate, coupled to conformational changes in the transmembrane section where the ions are translocated....... The marked increment during the last three years in the number of crystal structures of P-type ATPases has greatly improved our understanding of the similarities and differences of pumps with different ion specificities, since the structures of the Ca2+-ATPase, the Na+,K+-ATPase and the H+-ATPase can now...... be compared directly. Mechanisms for ion gating, charge neutralization and backflow prevention are starting to emerge from comparative structural analysis; and in combination with functional studies of mutated pumps this provides a framework for speculating on how the ions are bound and released as well...

  2. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Kaltenegger, Lisa [MPIA, Koenigstuhl 17, Heidelberg, D-69117 (Germany)

    2013-11-10

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results.

  3. Radiation damage studies of multi-guard ring p-type bulk diodes

    CERN Document Server

    Bortoletto, D; Günther, M; Grim, G P; Lander, R L; Willard, S; Li, Z

    1999-01-01

    Several diodes with different multi-guard ring structures were fabricated from 10 k OMEGA cm p-type bulk material. Studies on the performance of such devices are presented here. They include the measurement of the leakage current, breakdown voltage and charge collection efficiency before and after 2x10 sup 1 sup 4 p/cm sup 2 irradiation with 63.3 MeV kinetic protons. (author)

  4. Kinetics of self-interstitials reactions in p-type silicon irradiated with alpha particles

    Energy Technology Data Exchange (ETDEWEB)

    Makarenko, L.F., E-mail: makarenko@bsu.by [Department of Applied Mathematics and Computer Science, Belarusian State University, Independence Ave. 4, 220030 Minsk (Belarus); Moll, M. [CERN, Geneva (Switzerland); Evans-Freeman, J.H. [University of Canterbury, Christchurch (New Zealand); Lastovski, S.B.; Murin, L.I.; Korshunov, F.P. [Scientific-Practical Materials Research Centre of NAS of Belarus, Minsk (Belarus)

    2012-08-01

    New findings on the self-interstitial migration in p-type silicon are presented. They are based on experimental studies of the formation kinetics of defects related to interstitial carbon after irradiation with alpha particles. The main parameters characterizing the interaction rate of silicon self-interstitials with substitutional carbon atoms have been determined. A preliminary interpretation of the experimental data is given. The interpretation takes into account different diffusivities of self-interstitials in their singly and doubly ionized states.

  5. XANES and IR spectroscopy study of the electronic structure and chemical composition of porous silicon on n- and p-type substrates

    Energy Technology Data Exchange (ETDEWEB)

    Lenshin, A. S., E-mail: lenshinas@phys.vsu.ru; Kashkarov, V. M.; Seredin, P. V. [Voronezh State University (Russian Federation); Spivak, Yu. M.; Moshnikov, V. A. [LETI St. Petersburg State Electrotechnical University (Russian Federation)

    2011-09-15

    The differences in the electronic structure and composition of porous silicon samples obtained under identical conditions of electrochemical etching on the most commonly used n- and p-type substrates with different conductivities are demonstrated by X-ray absorption near-edge spectroscopy (XANES) and Fourier transform IR spectroscopy (FTIR) methods. It is shown that significantly higher oxidation and saturation with hydrogen is observed for the porous layer on n-type substrates.

  6. Record mobility in transparent p-type tin monoxide films and devices by phase engineering

    KAUST Repository

    Caraveo-Frescas, Jesus Alfonso

    2013-06-25

    Here, we report the fabrication of nanoscale (15 nm) fully transparent p-type SnO thin film transistors (TFT) at temperatures as low as 180 C with record device performance. Specifically, by carefully controlling the process conditions, we have developed SnO thin films with a Hall mobility of 18.71 cm2 V-1 s-1 and fabricated TFT devices with a linear field-effect mobility of 6.75 cm2 V-1 s -1 and 5.87 cm2 V-1 s-1 on transparent rigid and translucent flexible substrates, respectively. These values of mobility are the highest reported to date for any p-type oxide processed at this low temperature. We further demonstrate that this high mobility is realized by careful phase engineering. Specifically, we show that phase-pure SnO is not necessarily the highest mobility phase; instead, well-controlled amounts of residual metallic tin are shown to substantially increase the hole mobility. A detailed phase stability map for physical vapor deposition of nanoscale SnO is constructed for the first time for this p-type oxide. © 2013 American Chemical Society.

  7. Electronic inhomogeneity in n- and p-type PbTe detected by 125Te NMR

    Science.gov (United States)

    Levin, E. M.; Heremans, J. P.; Kanatzidis, M. G.; Schmidt-Rohr, K.

    2013-09-01

    125Te nuclear magnetic resonance spectra and spin-lattice relaxation of n- and p-type PbTe, self-doping narrow band-gap semiconductors, have been studied and compared to those of p-type GeTe. Spin-lattice relaxation in GeTe can be fit by one component, while that in both PbTe samples must be fit by at least two components, showing electronically homogeneous and inhomogeneous materials, respectively. For PbTe-based materials, the spin-lattice relaxation rate 1/T1 increases linearly with carrier concentration. The data for GeTe fall on the same line and allow us to extend this plot to higher concentrations. Long and short T1 components in both PbTe samples reflect “low,” ˜1017 cm-3, and “high,” ˜1018 cm-3, carrier concentration components. Carrier concentrations in both n- and p-type PbTe samples obtained from the Hall and Seebeck effects generally match the “high” carrier concentration component, and to some extent, ignore the “low” one. This demonstrates that the Hall and Seebeck effects may have a limited ability for the determination of carrier concentration in complex thermoelectric PbTe-based and other multicomponent materials.

  8. Effective p-type N-doped WS{sub 2} monolayer

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xu, E-mail: zhaoxu@htu.cn; Xia, Congxin; Wang, Tianxing; Peng, Yuting; Dai, Xianqi

    2015-11-15

    Based on density functional theory, the characteristics of n- and p-type dopants are investigated by means of group V and VII atoms substituting sulfur in the WS{sub 2} monolayer. Numerical results show that for each doping case, the formation energy is lower under W-rich condition, which indicates that it is energy favorable to incorporate group V and VII atoms into WS{sub 2} under W-rich experimental conditions. Moreover, compared with other dopant cases, N-doped WS{sub 2} monolayer owns the lowest formation energy. In particular, the transition level of (−1/0) is only 75 meV in the N-doped case, which indicates that N impurities can offer effective p-type carriers in the WS{sub 2} monolayer. - Highlights: • The formation energy is lower under W-rich conditions. • N-doped system owns the lowest formation energy compared with other atoms. • The transition level of N-doping in WS{sub 2} is 75 meV. • N impurities can offer effective p-type carriers in the WS{sub 2}.

  9. Demethoxycurcumin Is A Potent Inhibitor of P-Type ATPases from Diverse Kingdoms of Life.

    Science.gov (United States)

    Dao, Trong Tuan; Sehgal, Pankaj; Tung, Truong Thanh; Møller, Jesper Vuust; Nielsen, John; Palmgren, Michael; Christensen, Søren Brøgger; Fuglsang, Anja Thoe

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site of these pumps. Future research on biological effects of commercial preparations of curcumin should consider the heterogeneity of the material.

  10. p-Type Quasi-Mono Silicon Solar Cell Fabricated by Ion Implantation

    Directory of Open Access Journals (Sweden)

    Chien-Ming Lee

    2013-01-01

    Full Text Available The p-type quasi-mono wafer is a novel type of silicon material that is processed using a seed directional solidification technique. This material is a promising alternative to traditional high-cost Czochralski (CZ and float-zone (FZ material. Here, we evaluate the application of an advanced solar cell process featuring a novel method of ion implantation on p-type quasi-mono silicon wafer. The ion implantation process has simplified the normal industrial process flow by eliminating two process steps: the removal of phosphosilicate glass (PSG and the junction isolation process that is required after the conventional thermal POCl3 diffusion process. Moreover, the good passivation performance of the ion implantation process improves Voc. Our results show that, after metallization and cofiring, an average cell efficiency of 18.55% can be achieved using 156 × 156 mm p-type quasi-mono silicon wafer. Furthermore, the absolute cell efficiency obtained using this method is 0.47% higher than that for the traditional POCl3 diffusion process.

  11. Efficient synthesis of triarylamine-based dyes for p-type dye-sensitized solar cells

    Science.gov (United States)

    Wild, Martin; Griebel, Jan; Hajduk, Anna; Friedrich, Dirk; Stark, Annegret; Abel, Bernd; Siefermann, Katrin R.

    2016-05-01

    The class of triarylamine-based dyes has proven great potential as efficient light absorbers in inverse (p-type) dye sensitized solar cells (DSSCs). However, detailed investigation and further improvement of p-type DSSCs is strongly hindered by the fact that available synthesis routes of triarylamine-based dyes are inefficient and particularly demanding with regard to time and costs. Here, we report on an efficient synthesis strategy for triarylamine-based dyes for p-type DSSCs. A protocol for the synthesis of the dye-precursor (4-(bis(4-bromophenyl)amino)benzoic acid) is presented along with its X-ray crystal structure. The dye precursor is obtained from the commercially available 4(diphenylamino)benzaldehyde in a yield of 87% and serves as a starting point for the synthesis of various triarylamine-based dyes. Starting from the precursor we further describe a synthesis protocol for the dye 4-{bis[4‧-(2,2-dicyanovinyl)-[1,1‧-biphenyl]-4-yl]amino}benzoic acid (also known as dye P4) in a yield of 74%. All synthesis steps are characterized by high yields and high purities without the need for laborious purification steps and thus fulfill essential requirements for scale-up.

  12. Fabrication and electrical characterization of Al/DNA-CTMA/ p-type a-Si:H photodiode based on DNA-CTMA biomaterial

    Science.gov (United States)

    Siva Pratap Reddy, M.; Puneetha, Peddathimula; Lee, Young-Woong; Jeong, Seong-Hoon; Park, Chinho

    2017-01-01

    In this work, a deoxyribonucleic acid-cetyltrimethylammonium chloride (DNA-CTMA) biomaterial based p-type hydrogenated amorphous silicon ( a-Si:H) photodiode (PD) is fabricated and its electrical characteristics are investigated. The Al/DNA-CTMA/ p-type a-Si:H PD parameters are studied using current-voltage ( I-V), capacitancevoltage-frequency ( C-V-f) and conductance-voltage-frequency ( G/ω-V-f) measurements. The barrier height and the ideality factor of the diode are found to be 0.78 eV and 1.9, respectively. The electrical and photoconductivity properties of the diode are analyzed by using dark I-V and transient photocurrent techniques. The C-V-f and G/ω-V-f measurements indicate that the capacitance and conductance of the diode depend on the voltage and frequency, respectively. The experimental results reveal that the decreases in capacitance and the increases in conductance with an increase in frequency can be explained on the basis of interface states ( N SS ). Series resistance ( R S ) measurements are performed on the diode and discussed here. The obtained electrical parameters confirm that the Al/DNA-CTMA/ p-type a-Si:H PD can be used as an optical sensor for the development of commercial applications that are environmentally benign. [Figure not available: see fulltext.

  13. Completely transparent ohmic electrode on p-type AlGaN for UV LEDs with core-shell Cu@alloy nanosilk network (Conference Presentation)

    Science.gov (United States)

    Cai, Duanjun; Wang, Huachun; Huang, Youyang; Wu, Chenping; Chen, Xiaohong; Gao, Na; Wei, Tongbo T.; Wang, Junxi; Li, Shuping; Kang, Junyong

    2016-09-01

    Metal nanowire networks hold a great promise, which have been supposed the only alternative to ITO as transparent electrodes for their excellent performance in touch screen, LED and solar cell. It is well known that the difficulty in making transparent ohmic electrode to p-type high-Al-content AlGaN conducting layer has highly constrained the further development of UV LEDs. On the IWN-2014, we reported the ohmic contact to n, p-GaN with direct graphene 3D-coated Cu nanosilk network and the fabrication of complete blue LED. On the ICNS-2015, we reported the ohmic contact to n-type AlGaN conducting layer with Cu@alloy nanosilk network. Here, we further demonstrate the latest results that a novel technique is proposed for fabricating transparent ohmic electrode to high-Al-content AlGaN p-type conducting layer in UV LEDs using Cu@alloy core-shell nanosilk network. The superfine copper nanowires (16 nm) was synthesized for coating various metals such as Ni, Zn, V or Ti with different work functions. The transmittance showed a high transparency (> 90%) over a broad wavelength range from 200 to 3000 nm. By thermal annealing, ohmic contact was achieved on p-type Al0.5Ga0.5N layer with Cu@Ni nanosilk network, showing clearly linear I-V curve. By skipping the p-type GaN cladding layer, complete UV LED chip was fabricated and successfully lit with bright emission at 276 nm.

  14. Ivermectin is a nonselective inhibitor of mammalian P-type ATPases.

    Science.gov (United States)

    Pimenta, Paulo Henrique Cotrim; Silva, Claudia Lucia Martins; Noël, François

    2010-02-01

    Ivermectin is a large spectrum antiparasitic drug that is very safe at the doses actually used. However, as it is being studied for new applications that would require higher doses, we should pay attention to its effects at high concentrations. As micromolar concentrations of ivermectin have been reported to inhibit the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA), we decided to investigate its putative inhibitory effect on other two important P-type ATPases, namely the Na(+) , K(+)-ATPase and H(+)/K(+)-ATPase. We first extended the data on SERCA, using preparations from rat enriched in SERCA1a (extensor digitorum longus) and 1b (heart) isoforms. Secondly, we tested the effect of ivermectin in two preparations of rat Na(+), K(+)-ATPase in order to appreciate its putative selectivity towards the alpha(1) isoform (kidney) and the alpha(2)/alpha(3) isoforms (brain), and in an H(+)/K(+)-ATPase preparation from rat stomach. Ivermectin inhibited all these ATPases with similar IC(50) values (6-17 microM). With respect to the inhibition of the Na(+), K(+)-ATPase, ivermectin acts by a mechanism different from the classical cardiac glycosides, based on selectivity towards the isoforms, sensibility to the antagonistic effect of K(+) and to ionic conditions favoring different conformations of the enzyme. We conclude that ivermectin is a nonselective inhibitor of three important mammalian P-type ATPases, which is indicative of putative important adverse effects if this drug were used at high doses. As a consequence, we propose that novel analogs of ivermectin should be developed and tested both for their parasitic activity and in vitro effects on P-type ATPases.

  15. Does p-type ohmic contact exist in WSe2-metal interfaces?

    Science.gov (United States)

    Wang, Yangyang; Yang, Ruo Xi; Quhe, Ruge; Zhong, Hongxia; Cong, Linxiao; Ye, Meng; Ni, Zeyuan; Song, Zhigang; Yang, Jinbo; Shi, Junjie; Li, Ju; Lu, Jing

    2015-12-01

    Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for the selection of favorable metal electrodes in ML/BL WSe2 devices.Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for

  16. Initial results from 3D-DDTC detectors on p-type substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zoboli, A., E-mail: zoboli@disi.unitn.i [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento, and INFN, Sezione di Padova (Gruppo Collegato di Trento), Via Sommarive, 14, I-38100 Povo di Trento (Italy); Boscardin, M. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi, Via Sommarive, 18, I-38100 Povo di Trento (Italy); Bosisio, L. [Dipartimento di Fisica, Universita di Trieste, and INFN, Sezione di Trieste, Via A. Valerio, 2, I-34127 Trieste (Italy); Dalla Betta, G.-F. [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento, and INFN, Sezione di Padova (Gruppo Collegato di Trento), Via Sommarive, 14, I-38100 Povo di Trento (Italy); Piemonte, C.; Ronchin, S.; Zorzi, N. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi, Via Sommarive, 18, I-38100 Povo di Trento (Italy)

    2010-01-11

    Owing to their superior radiation hardness compared to planar detectors, 3D detectors are one of the most promising technologies for the LHC upgrade foreseen in 2017. Fondazione Bruno Kessler has developed 3D Double-side Double-Type Column (3D-DDTC) detectors providing a technological simplifications with respect to a standard 3D process while aiming at comparable detector performance. We present selected results from the electrical characterization of 3D-DDTC structures from the second batch made on p-type substrates, supported also by TCAD simulations.

  17. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg; Meloni, Gabriele

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis1. In prokaryotes and photosynthetic eukaryotes, Zn2+-transporting P-type ATPases of class IB (Znt....... The structures reveal a similar fold to Cu+-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn2+ ions by the transporter. The E2P structure...

  18. About the Nature of Electroluminescence Centers in Plastically Deformed Crystals of p-type Silicon

    Directory of Open Access Journals (Sweden)

    B.V. Pavlyk

    2015-10-01

    Full Text Available The paper describes research of dislocation electroluminescence of single crystal p-type silicon with a high concentration of dislocations on the surface (111. It is shown the reaction of the luminescence spectra and capacitive-modulation spectra of samples after high-temperature annealing in an atmosphere of flowing oxygen. The analysis of the results lets us to establish the nature of recombination centers and their reorganization under high-temperature annealing. It is shown that deposition of Al film on the substrate p-Si leads to the formation of strain capacity and the localization of defects in the surface layer that corresponds to luminescence centers.

  19. Elastic constants determined by nanoindentation for p-type thermoelectric half-Heusler

    Energy Technology Data Exchange (ETDEWEB)

    Gahlawat, S.; Wheeler, L.; White, K. W., E-mail: zren@uh.edu, E-mail: kwwhite@uh.edu [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); He, R.; Chen, S.; Ren, Z. F., E-mail: zren@uh.edu, E-mail: kwwhite@uh.edu [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States)

    2014-08-28

    This paper presents a study of the elastic properties of the p-type thermoelectric half-Heusler material, Hf{sub 0.44}Zr{sub 0.44}Ti{sub 0.12}CoSb{sub 0.8}Sn{sub 0.2}, using nanoindentation. Large grain-sized polycrystalline specimens were fabricated for these measurements, providing sufficient indentation targets within single grains. Electron Backscatter Diffraction methods indexed the target grains for the correlation needed for our elastic analysis of individual single crystals for this cubic thermoelectric material. Elastic properties, including the Zener ratio and the Poisson ratio, obtained from the elasticity tensor are also reported.

  20. Ferromagnetic-resonance induced electromotive forces in Ni81Fe19 | p-type diamond

    Science.gov (United States)

    Fukui, Naoki; Morishita, Hiroki; Kobayashi, Satoshi; Miwa, Shinji; Mizuochi, Norikazu; Suzuki, Yoshishige

    2016-10-01

    We report on direct-current (DC) electromotive forces (emfs) in a nickel-iron alloy (Ni81 Fe19) | p-type diamond under the ferromagnetic resonance of the Ni81Fe19 layer at room temperature. The observed DC emfs take its maximum around the ferromagnetic resonant frequency of the Ni81Fe19, and their signs are reversed by reversing the direction of an externally-applied magnetic field; it shows that the observed DC emfs are spin-related emfs.

  1. Single-structure heater and temperature sensor using a p-type polycrystalline diamond resistor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G.S.; Aslam, D.M. [Michigan State Univ., East Lansing, MI (United States). Dept. of Electrical Engineering

    1996-05-01

    Heat generation and temperature sensing are required for heating applications and for liquid level sensors, mass flow meters, and vacuum and pressure gauges which are based on variations of heat dissipation. Heat generation and temperature sensing are reported in a single p-type diamond resistor fabricated on an oxidized Si substrate using diamond film technology compatible with integrated circuit (IC) processing. Power densities in excess of 600 W/in.{sup 2} are observed for the heaters. The temperature response of the sensor is characterized in the temperature range of 300--725 K. Such a diamond heater/sensor device is reported for the first time.

  2. Photovoltaic properties of ZnO nanorods/p-type Si heterojunction structures

    Directory of Open Access Journals (Sweden)

    Rafal Pietruszka

    2014-02-01

    Full Text Available Selected properties of photovoltaic (PV structures based on n-type zinc oxide nanorods grown by a low temperature hydrothermal method on p-type silicon substrates (100 are investigated. PV structures were covered with thin films of Al doped ZnO grown by atomic layer deposition acting as transparent electrodes. The investigated PV structures differ in terms of the shapes and densities of their nanorods. The best response is observed for the structure containing closely-spaced nanorods, which show light conversion efficiency of 3.6%.

  3. Methods for enhancing P-type doping in III-V semiconductor films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Feng; Stringfellow, Gerald; Zhu, Junyi

    2017-08-01

    Methods of doping a semiconductor film are provided. The methods comprise epitaxially growing the III-V semiconductor film in the presence of a dopant, a surfactant capable of acting as an electron reservoir, and hydrogen, under conditions that promote the formation of a III-V semiconductor film doped with the p-type dopant. In some embodiments of the methods, the epitaxial growth of the doped III-V semiconductor film is initiated at a first hydrogen partial pressure which is increased to a second hydrogen partial pressure during the epitaxial growth process.

  4. P-Type Doping of GaN by Mg+ Implantation

    Institute of Scientific and Technical Information of China (English)

    YAO Shu-De; ZHAO Qiang; ZHOU Sheng-Qiang; YANG Zi-Jian; LU Yi-Hong; SUN Chang-Chun; SUN Chang; ZHANG Guo-Yi; VANTOMME Andre; PIPELEERS Bert

    2003-01-01

    Mg+ and Mg++P+ were introduced into GaN by ion implantation. The structure and crystalline quality of the GaN samples were analysed by Rutherford backscattering and channelling spectrometry before (xmin = 1.6%) and after implantation (Xmin = 4.1%). X-ray diffraction reveals the existence of implantation-induced damage in the case of post-implantation followed by rapid thermal annealing. The resistivity, average factor, carrier concentration and carrier mobility were measured by the Hall effect. The transformation from n-type to p-type for GaN was observed.

  5. Transient expression of P-type ATPases in tobacco epidermal cells

    DEFF Research Database (Denmark)

    Pedas, Lisbeth Rosager; Palmgren, Michael Broberg; Lopez Marques, Rosa Laura

    2016-01-01

    Transient expression in tobacco cells is a convenient method for several purposes such as analysis of protein-protein interactions and the subcellular localization of plant proteins. A suspension of Agrobacterium tumefaciens cells carrying the plasmid of interest is injected into the intracellular...... for example protein-protein interaction studies. In this chapter, we describe the procedure to transiently express P-type ATPases in tobacco epidermal cells, with focus on subcellular localization of the protein complexes formed by P4-ATPases and their β-subunits....

  6. Gas doping ratio effects on p-type hydrogenated nanocrystalline silicon thin films grown by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, P.Q. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: robt@sjtu.edu.cn; Zhou, Z.B. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: zbzhou@sjtu.edu.cn; Chan, K.Y. [Thin Film Laboratory, Faculty of Engineering, Multimedia University, Jalan Multimedia, Cyberjaya 63100, Selangor (Malaysia); Tang, D.Y.; Cui, R.Q.; Dou, X.M. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2008-12-30

    Hydrogenated nanocrystalline silicon (nc-Si:H) grown by hot-wire chemical vapor deposition (HWCVD) has recently drawn significant attention in the area of thin-film large area optoelectronics due to possibility of high deposition rate. We report on the effects of diborane (B{sub 2}H{sub 6}) doping ratio on the microstructural and optoelectrical properties of the p-type nc-Si:H thin films grown by HWCVD at low substrate temperature of 200 deg. C and with high hydrogen dilution ratio of 98.8%. An attempt has been made to elucidate the boron doping mechanism of the p-type nc-Si:H thin films deposited by HWCVD and the correlation between the B{sub 2}H{sub 6} doping ratio, crystalline volume fraction, optical band gap and dark conductivity.

  7. Hybrid p-type ZnO film and n-type ZnO nanorod p-n homo-junction for efficient photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Hyun; Lee, Jun Seok; Lee, Sang Hyo; Nam, Hye Won [Novel Functional Materials and Device Lab, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Hong, Jin Pyo, E-mail: jphong@hanyang.ac.k [Novel Functional Materials and Device Lab, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Cha, Seoung Nam; Park, Young Jun; Kim, Jong Min [Samsung Advanced Institute of Technology, P.O. Box 11, 1 Suwon 440-600 (Korea, Republic of)

    2010-09-01

    Simple hybrid p-n homo-junctions using p-type ZnO thin films and n-type nanorods grown on fluorine tin oxide (FTO) substrates for photovoltaic applications are described. The ZnO nanorods (1.5 {mu}m) were synthesized via an aqueous solution method with zinc nitrate hexahydrate and hexamethylenetetramine on ZnO seed layers. The 10-nm-thick ZnO seed layers showed n-type conductivity on FTO substrates and were deposited with a sputtering-based method. After synthesizing ZnO nanorods, aluminum-nitride co-doped p-type ZnO films (200 nm) were efficiently grown using pre-activated nitrogen (N) plasma sources with an inductively-coupled dual-target co-sputtering system. The structural and electrical properties of hybrid p-n homo-junctions were investigated by scanning electron microscopy, transmittance spectrophotometry, and I-V measurements.

  8. The Tamiflu saga continues: will our conduct change after the publication of the latest systematic review on benefits and harms of oseltamivir?

    Science.gov (United States)

    Bachelet, Vivienne C

    2014-05-20

    In 2013, we wrote about the harm, waste and deception stemming from conducts adopted by the pharmaceutical industry, by concealing raw data and Clinical Study Reports (CSRs) from the regulator’s view when requesting the marketing patent. We described the case of Tamiflu (Roche), a drug that has been widely used in our population and profusely prescribed by physicians. Health authorities, entailing a great cost for the countries in the region, have also purchased it. In this editorial, we will show how the idea of using antivirals for prophylaxis and treatment of influenza took hold, starting from the first enthusiastic recommendations up to the systematic review published last month in the BMJ.

  9. Improved continuity of reduced graphene oxide on polyester fabric by use of polypyrrole to achieve a highly electro-conductive and flexible substrate

    Energy Technology Data Exchange (ETDEWEB)

    Berendjchi, Amirhosein [Department of Textile Engineering, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Khajavi, Ramin, E-mail: khajavi@azad.ac.ir [Nano Technology Research Center, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Yousefi, Ali Akbar [Faculty of Polymer Processing, Iran Polymer and Petrochemical Institute, Tehran (Iran, Islamic Republic of); Yazdanshenas, Mohammad Esmail [Department of Textile Engineering, Yazd Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of)

    2016-02-15

    Graphical abstract: - Highlights: • Discontinuity of reduced graphene oxide (RGO) coated polyester fabric (PET) substrate was overcome by filling the gaps by in situ chemical oxidative polymerization of polypyrrole (PPy). • The RGO–PPy coated samples exhibited 53% and 263% lower surface resistivity values (5 Ω/sq) than samples coated only with PPy (12 Ω/sq) and RGO (1300 Ω/sq), respectively. • The RGO–PPy coated fabric displayed other properties, such as excellent UV blocking (UPF = 73), antibacterial activity, improved electrochemical behavior and thermal stability which make it a multifunctional fabric. - Abstract: A flexible and highly conductive fabric can be applied for wearable electronics and as a pliable counter electrode for photovoltaics. Methods such as surface coating of fabrics with conductive polymers and materials have been developed, but the roughness of fabric is a challenge because it creates discontinuity in the coated layer. The present study first coated polyethylene terephthalate (PET) fabric with reduced graphene oxide sheets; RGO and then filled the gaps with polypyrrole (PPy). The samples were first dipped in graphene oxide (GO) and then reduced to RGO. They were next coated with PPy by in situ polymerization. The results showed that the presence of oxidative agent during synthesis of PPy oxidized the RGO to some extent on the previously RGO-coated samples. PPy was more uniform on samples pre-coated with RGO in comparison those coated with raw PET. The RGO–PPy coated samples exhibited 53% and 263% lower surface resistivity values than samples coated only with PPy and RGO, respectively. There was no significant difference between the tenacity of samples but the bending rigidity of samples increased. The RGO–PPy coated fabric displayed properties, such as excellent UV blocking (UPF = 73), antibacterial activity, improved electrochemical behavior and thermal stability which make it a multifunctional fabric.

  10. Dark current studies on a normal-conducting high-brightness very-high-frequency electron gun operating in continuous wave mode

    Directory of Open Access Journals (Sweden)

    R. Huang

    2015-01-01

    Full Text Available We report on measurements and analysis of a field-emitted electron current in the very-high-frequency (VHF gun, a room temperature rf gun operating at high field and continuous wave (CW mode at the Lawrence Berkeley National Laboratory (LBNL. The VHF gun is the core of the Advanced Photo-injector Experiment (APEX at LBNL, geared toward the development of an injector for driving the next generation of high average power x-ray free electron lasers. High accelerating fields at the cathode are necessary for the high-brightness performance of an electron gun. When coupled with CW operation, such fields can generate a significant amount of field-emitted electrons that can be transported downstream the accelerator forming the so-called “dark current.” Elevated levels of a dark current can cause radiation damage, increase the heat load in the downstream cryogenic systems, and ultimately limit the overall performance and reliability of the facility. We performed systematic measurements that allowed us to characterize the field emission from the VHF gun, determine the location of the main emitters, and define an effective strategy to reduce and control the level of dark current at APEX. Furthermore, the energy spectra of isolated sources have been measured. A simple model for energy data analysis was developed that allows one to extract information on the emitter from a single energy distribution measurement.

  11. A P-type ATPase importer that discriminates between essential and toxic transition metals.

    Science.gov (United States)

    Lewinson, Oded; Lee, Allen T; Rees, Douglas C

    2009-03-24

    Transition metals, although being essential cofactors in many physiological processes, are toxic at elevated concentrations. Among the membrane-embedded transport proteins that maintain appropriate intracellular levels of transition metals are ATP-driven pumps belonging to the P-type ATPase superfamily. These metal transporters may be differentiated according to their substrate specificities, where the majority of pumps can extrude either silver and copper or zinc, cadmium, and lead. In the present report, we have established the substrate specificities of nine previously uncharacterized prokaryotic transition-metal P-type ATPases. We find that all of the newly identified exporters indeed fall into one of the two above-mentioned categories. In addition to these exporters, one importer, Pseudomonas aeruginosa Q9I147, was also identified. This protein, designated HmtA (heavy metal transporter A), exhibited a different substrate recognition profile from the exporters. In vivo metal susceptibility assays, intracellular metal measurements, and transport experiments all suggest that HmtA mediates the uptake of copper and zinc but not of silver, mercury, or cadmium. The substrate selectivity of this importer ensures the high-affinity uptake of essential metals, while avoiding intracellular contamination by their toxic counterparts.

  12. Analysis of carrier concentration, lifetime, and electron mobility on p-type HgCdTe

    Science.gov (United States)

    Yoo, Sang Dong; Kwack, Kae Dal

    1998-03-01

    Minority carrier transport characteristics of vacancy-doped p-type HgCdTe such as carrier concentration, lifetime, and mobility are investigated. In the calculation of the carrier concentration two acceptor levels—a donor level and a trap level—were taken into account. The acceptor levels have been described by two models—two independent singly ionized levels and a divalent level with two ionization energies. When each model was examined by calculating electron mobility as a function of temperature, the latter was found to be more accurate. Electron mobility as a function of majority carrier concentration was also presented for both n-type and p-type HgCdTe with 0.225 Cd mole fraction. Steady state electron lifetime was computed assuming the acceptor levels and the trap level would act as Schokley-Read-Hall type recombination centers. The calculated results using the divalent acceptor model were in good agreement with the experimental data.

  13. Synthesis and characterization of p-type boron-doped IIb diamond large single crystals

    Institute of Scientific and Technical Information of China (English)

    Li Shang-Sheng; Ma Hong-An; Li Xiao-Lei; Su Tai-Chao; Huang Guo-Feng; Li Yong; Jia Xiao-Peng

    2011-01-01

    High-quality p-type boron-doped II0b diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond.

  14. EEG/MEG forward simulation through h- and p-type finite elements

    Energy Technology Data Exchange (ETDEWEB)

    Pursiainen, S [Institute of Mathematics, Box 1100, FI-02015 Helsinki University of Technology (Finland)], E-mail: sampsa.pursiainen@tkk.fi

    2008-07-15

    Electro/Magnetoencephalography (EEG/MEG) is a non-invasive imaging modality, in which a primary current density generated by the neural activity in the brain is to be reconstructed from external electric potential/magnetic field measurements. This work focuses on effective and accurate simulation of the EEG/MEG forward model through the h- and p-versions of the finite element method (h- and p-FEM). The goal is to compare the effectiveness of these two versions in forward simulation. Both h- and p-type forward simulations are described and implemented, and the technical solutions found are discussed. These include, for example, suitable ways to generate a finite element mesh for a real head geometry through the use of different element types. Performances of the two implemented forward simulation types are compared by measuring directly the forward modeling error, as well as by computing reconstructions through a regularized FOCUSS (FOCal Underdetermined System Solver) algorithm. The results obtained suggest that the p-type performs better in terms of the forward modeling error. However, both types perform well in regularized FOCUSS reconstruction.

  15. Wide band gap p-type windows by CBD and SILAR methods

    Energy Technology Data Exchange (ETDEWEB)

    Sankapal, B.R.; Goncalves, E.; Ennaoui, A.; Lux-Steiner, M.Ch

    2004-03-22

    Chemical deposition methods, namely, chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) have been used to deposit wide band gap p-type CuI and CuSCN thin films at room temperature (25 deg. C) in aqueous medium. Growth of these films requires the use of Cu (I) cations as a copper ions source. This is achieved by complexing Cu (II) ions using Na{sub 2}S{sub 2}O{sub 3}. The anion sources are either KI as iodine or KSCN as thiocyanide ions for CuI and CuSCN films, respectively. The preparative parameters are optimized with the aim to use these p-type materials as windows for solar cells. Different substrates are used, namely: glass, fluorine doped tin oxide coated glass and CuInS{sub 2} (CIS). X-ray diffraction, scanning electron microscopy, atomic force microscopy and optical absorption spectroscopy are used for structural, surface morphological and optical studies, and the results are discussed.

  16. Carrier induced local moment magnetization in p-type Sn1-xMnxTe

    Science.gov (United States)

    Behera, Sashi S.; Tripathi, Pratibha; Nayak, Sanjeev K.; Tripathi, Gouri S.

    2017-08-01

    We derive a theory of carrier induced local moment magnetization of p-type Sn1-xMnxTe based on the Hubbard model, k → · π → electronic structure method (k → is the electronic wave vector and π → is the relativistic momentum operator) and the statistical paramagnetic approach for the localized moments. The Hubbard model is used to derive an internal exchange magnetic field. The difference in exchange self-energy is expressed in terms of an internal exchange field that is proportional to the parameter U, the onsite Coulomb repulsion, and the spin-density of carriers. In the present theory, the k → · π → + U model is integrated with the statistical paramagnetic theory for localized spins, which is then solved in a self-consistent manner by adding the exchange field to the applied field. The technique is applied to study the magnetic properties of p-type Sn1-xMnxTe, an important material for spintronics devices. The local moment magnetization calculated using the total magnetic field self-consistently agrees with the experimental observations. Magnetization and the exchange field studied as functions of the applied field, temperature and carrier concentration yield results on expected lines. Ours is a mechanism that is different from the RKKY interaction, normally invoked for carrier induced ferromagnetism and is thus a novelty.

  17. Anabaena sp. DyP-type peroxidase is a tetramer consisting of two asymmetric dimers.

    Science.gov (United States)

    Yoshida, Toru; Ogola, Henry Joseph Oduor; Amano, Yoshimi; Hisabori, Toru; Ashida, Hiroyuki; Sawa, Yoshihiro; Tsuge, Hideaki; Sugano, Yasushi

    2016-01-01

    DyP-type peroxidases are a newly discovered family of heme peroxidases distributed from prokaryotes to eukaryotes. Recently, using a structure-based sequence alignment, we proposed the new classes, P, I and V, as substitutes for classes A, B, C, and D [Arch Biochem Biophys 2015;574:49-55]. Although many class V enzymes from eukaryotes have been characterized, only two from prokaryotes have been reported. Here, we show the crystal structure of one of these two enzymes, Anabaena sp. DyP-type peroxidase (AnaPX). AnaPX is tetramer formed from Cys224-Cys224 disulfide-linked dimers. The tetramer of wild-type AnaPX was stable at all salt concentrations tested. In contrast, the C224A mutant showed salt concentration-dependent oligomeric states: in 600 mM NaCl, it maintained a tetrameric structure, whereas in the absence of salt, it dissociated into monomers, leading to a reduction in thermostability. Although the tetramer exhibits non-crystallographic, 2-fold symmetry in the asymmetric unit, two subunits forming the Cys224-Cys224 disulfide-linked dimer are related by 165° rotation. This asymmetry creates an opening to cavities facing the inside of the tetramer, providing a pathway for hydrogen peroxide access. Finally, a phylogenetic analysis using structure-based sequence alignments showed that class V enzymes from prokaryotes, including AnaPX, are phylogenetically closely related to class V enzymes from eukaryotes.

  18. Valence band states in Si-based p-type delta-doped field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Orozco, J C; Vlaev, Stoyan J, E-mail: jcmover@correo.unam.m [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060, Zacatecas, Zac. (Mexico)

    2009-05-01

    We present tight-binding calculations of the hole level structure of delta-doped Field Effect Transistor in a Si matrix within the first neighbors sp{sup 3}s* semi-empirical tight-binding model including spin. We employ analytical expressions for Schottky barrier potential and the p-type delta-doped well based on a Thomas-Fermi approximation, we consider these potentials as external ones, so in the computations they are added to the diagonal terms of the tight-binding Hamiltonian, by this way we have the possibility to study the energy levels behavior as we vary the backbone parameters in the system: the two-dimensional impurity density (p{sub 2d}) of the p-type delta-doped well and the contact voltage (V{sub c}). The aim of this calculation is to demonstrate that the tight-binding approximation is suitable for device characterization that permits us to propose optimal values for the input parameters involved in the device design.

  19. Piezo-phototronic effect on electroluminescence properties of p-type GaN thin films.

    Science.gov (United States)

    Hu, Youfan; Zhang, Yan; Lin, Long; Ding, Yong; Zhu, Guang; Wang, Zhong Lin

    2012-07-11

    We present that the electroluminescence (EL) properties of Mg-doped p-type GaN thin films can be tuned by the piezo-phototronic effect via adjusting the minority carrier injection efficiency at the metal-semiconductor (M-S) interface by strain induced polarization charges. The device is a metal-semiconductor-metal structure of indium tin oxide (ITO)-GaN-ITO. Under different straining conditions, the changing trend of the transport properties of GaN films can be divided into two types, corresponding to the different c-axis orientations of the films. An extreme value was observed for the integral EL intensity under certain applied strain due to the adjusted minority carrier injection efficiency by piezoelectric charges introduced at the M-S interface. The external quantum efficiency of the blue EL at 430 nm was changed by 5.84% under different straining conditions, which is 1 order of magnitude larger than the change of the green peak at 540 nm. The results indicate that the piezo-phototronic effect has a larger impact on the shallow acceptor states related EL process than on the one related to the deep acceptor states in p-type GaN films. This study has great significance on the practical applications of GaN in optoelectronic devices under a working environment where mechanical deformation is unavoidable such as for flexible/printable light emitting diodes.

  20. p-Type semiconducting nickel oxide as an efficiency-enhancing anodal interfacial layer in bulk heterojunction solar cells

    Science.gov (United States)

    Irwin, Michael D; Buchholz, Donald B; Marks, Tobin J; Chang, Robert P. H.

    2014-11-25

    The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode, a p-type semiconductor layer formed on the anode, and an active organic layer formed on the p-type semiconductor layer, where the active organic layer has an electron-donating organic material and an electron-accepting organic material.

  1. Persistent Hydrogen Production by the Photo-Assisted Microbial Electrolysis Cell Using a p-Type Polyaniline Nanofiber Cathode.

    Science.gov (United States)

    Jeon, Yongwon; Kim, Sunghyun

    2016-12-08

    A microbial electrolysis cell, though considered as a promising, environmentally friendly technology for hydrogen production, suffers from concomitant production of methane. The high hydrogen/methane ratio at the initial operation stage decreases with time. Here we report for the first time the photoassisted microbial electrolysis cell (MEC) for persistent hydrogen production using polyaniline nanofibers as a cathode. Under 0.8 V external bias and laboratory fluorescent light illumination in a single-chamber MEC, continuous hydrogen production from acetate at a rate of 1.78 mH2 (3)  m(-3)  d(-1) with 79.2 % overall hydrogen recovery was achieved with negligible methane formation for six months. Energy efficiencies based on input electricity as well as input electricity plus substrate were 182 and 66.2 %, respectively. This was attributed to the p-type-semiconductor characteristics of polyaniline nanofibers in which photoexcited electrons are used to reduce protons at the surface and holes are reduced with electrons originating from acetate oxidation at the anode. This method can be extended to microbial wastewater treatment for hydrogen production. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Cation Defects and Conductivity in Transparent Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Exarhos, Gregory J.; Windisch, Charles F.; Ferris, Kim F.; Owings, Robert R.

    2007-10-24

    High quality doped zinc oxide and mixed transition metal spinel oxide films have been deposited by means of sputter deposition from metal and metal oxide targets, and by spin casting from aqueous or alcoholic precursor solutions. Deposition conditions and post-deposition processing are found to alter cation oxidation states and their distributions in both oxide materials resulting in marked changes to both optical transmission and electrical response. For ZnO, partial reduction of the neat or doped material by hydrogen treatment of the heated film or by electrochemical processing renders the oxide n-type conducting. Continued reduction was found to diminish conductivity. In contrast, oxidation of the infrared transparent p-type spinel conductors typified by NiCo2O4 was found to increase conductivity. The disparate behavior of these two materials is caused in part by the sign of the charge carrier and by the existence of two different charge transport mechanisms that are identified as free carrier conduction and polaron hopping. While much work has been reported concerning structure/property relationships in the free carrier conducting oxides, there is a significantly smaller body of information on transparent polaron conductors. In this paper, we identify key parameters that promote conductivity in mixed metal spinel oxides and compare their behavior with that of the free carrier TCO’s.

  3. Electronic characteristics of p-type transparent SnO monolayer with high carrier mobility

    Science.gov (United States)

    Du, Juan; Xia, Congxin; Liu, Yaming; Li, Xueping; Peng, Yuting; Wei, Shuyi

    2017-04-01

    More recently, two-dimensional (2D) SnO nanosheets are attaching great attention due to its excellent carrier mobility and transparent characteristics. Here, the stability, electronic structures and carrier mobility of SnO monolayer are investigated by using first-principles calculations. The calculations of the phonon dispersion spectra indicate that SnO monolayer is dynamically stable. Moreover, the band gap values are decreased from 3.93 eV to 2.75 eV when the tensile strain is applied from 0% to 12%. Interestingly, SnO monolayer is a p-type transparent semiconducting oxide with hole mobility of 641 cm2 V-1 s-1, which is much higher than that of MoS2 monolayer. These findings make SnO monolayer becomes a promising 2D material for applications in nanoelectronic devices.

  4. P-type calcium channels are blocked by the alkaloid daurisoline.

    Science.gov (United States)

    Lu, Y M; Fröstl, W; Dreessen, J; Knöpfel, T

    1994-07-21

    IN looking for a structurally defined non-peptide P-channel blocker we have tested the alkaloid daurisoline which has been isolated from traditional Chinese medicinal herb (Menispermum dauricum) used for the treatment of epilepsy, hypertension and asthma. We have found that daurisoline is an inhibitor of omega-Aga-IVA sensitive barium currents in cerebellar Purkinje cells and of excitatory postsynaptic potentials evoked in Purkinje cells by stimulating parallel fibres in acutely prepared cerebellar slices. Daurisoline did not significantly affect omega-Aga-IVA-insensitive barium currents recorded from granule cells freshly isolated from rat cerebellum. Daurisoline passes the blood-brain barrier and will, therefore, facilitate the functional characterization of brain calcium channels as well as the exploration of P-type calcium channels as possible drug targets.

  5. A re-examination of cobalt-related defects in n- and p-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Scheffler, Leopold; Kolkovsky, Vladimir; Weber, Joerg [Technische Universitaet Dresden, 01069 Dresden (Germany)

    2012-10-15

    In the present work cobalt-doped n- and p-type silicon samples were studied by means of deep level transient spectroscopy (DLTS) and Laplace-DLTS (LDLTS). We demonstrate that two dominant DLTS peaks previously assigned to a substitutional Co defect have different annealing behaviour and therefore belong to different defects. After wet chemical etching three other peaks (E90, E140 and H160) were observed in the samples. The intensity of the peaks becomes larger in the H-plasma treated samples. This together with depth profiling demonstrates that the peaks are hydrogen-related defects. The origin of the peaks will be discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Low-temperature TCT characterization of heavily proton irradiated p-type magnetic Czochralski silicon detectors

    CERN Document Server

    Härkönen, J; Luukka, P; Kassamakov, I; Autioniemi, M; Tuominen, E; Sane, P; Pusa, P; Räisänen, J; Eremin, V; Verbitskaya, E; Li, Z

    2007-01-01

    n+/p−/p+ pad detectors processed at the Microelectronics Center of Helsinki University of Technology on boron-doped p-type high-resistivity magnetic Czochralski (MCz-Si) silicon substrates have been investigated by the transient current technique (TCT) measurements between 100 and 240 K. The detectors were irradiated by 9 MeV protons at the Accelerator Laboratory of University of Helsinki up to 1 MeV neutron equivalent fluence of 2×1015 n/cm2. In some of the detectors the thermal donors (TD) were introduced by intentional heat treatment at 430 °C. Hole trapping time constants and full depletion voltage values were extracted from the TCT data. We observed that hole trapping times in the order of 10 ns were found in heavily (above 1×1015 neq/cm2) irradiated samples. These detectors could be fully depleted below 500 V in the temperature range of 140–180 K.

  7. Origin of resistivity anomaly in p-type leads chalcogenide multiphase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Aminorroaya Yamini, Sima, E-mail: sima@uow.edu.au, E-mail: jsnyder@caltech.edu; Dou, Shi Xue [Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); Mitchell, David R. G. [Electron Microscopy Centre (EMC), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); Wang, Heng [Materials Science, California Institute of Technology, Pasadena, CA 91125 (United States); Gibbs, Zachary M. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (United States); Pei, Yanzhong [School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804 (China); Snyder, G. Jeffrey, E-mail: sima@uow.edu.au, E-mail: jsnyder@caltech.edu [Electron Microscopy Centre (EMC), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); ITMO University, Saint Petersburg (Russian Federation)

    2015-05-15

    The electrical resistivity curves for binary phase compounds of p-type lead chalcogenide (PbTe){sub (0.9−x)}(PbSe){sub 0.1}(PbS){sub x,} (x = 0.15, 0.2, 0.25), which contain PbS-rich secondary phases, show different behaviour on heating and cooling between 500-700 K. This is contrast to single phase compounds which exhibit similar behaviour on heating and cooling. We correlate these anomalies in the electrical resistivities of multiphase compounds to the variation in phase composition at high temperatures. The inhomogeneous distribution of dopants between the matrix and secondary phase is found to be crucial in the electronic transport properties of the multiphase compounds. These results can lead to further advances in designing composite Pb-chalcogenides with high thermoelectric performance.

  8. Microhardness of carbon-doped (111) p-type Czochralski silicon

    Science.gov (United States)

    Danyluk, S.; Lim, D. S.; Kalejs, J.

    1985-01-01

    The effect of carbon on (111) p-type Czochralski silicon is examined. The preparation of the silicon and microhardness test procedures are described, and the equation used to determine microhardness from indentations in the silicon wafers is presented. The results indicate that as the carbon concentration in the silicon increases the microhardness increases. The linear increase in microhardness is the result of carbon hindering dislocation motion, and the effect of temperature on silicon deformation and dislocation mobility is explained. The measured microhardness was compared with an analysis which is based on dislocation pinning by carbon; a good correlation was observed. The Labusch model for the effect of pinning sites on dislocation motion is given.

  9. Photostable p-type dye-sensitized photoelectrochemical cells for water reduction.

    Science.gov (United States)

    Ji, Zhiqiang; He, Mingfu; Huang, Zhongjie; Ozkan, Umit; Wu, Yiying

    2013-08-14

    A photostable p-type NiO photocathode based on a bifunctional cyclometalated ruthenium sensitizer and a cobaloxime catalyst has been created for visible-light-driven water reduction to produce H2. The sensitizer is anchored firmly on the surface of NiO, and the binding is resistant to the hydrolytic cleavage. The bifunctional sensitizer can also immobilize the water reduction catalyst. The resultant photoelectrode exhibits superior stability in aqueous solutions. Stable photocurrents have been observed over a period of hours. This finding is useful for addressing the degradation issue in dye-sensitized photoelectrochemical cells caused by desorption of dyes and catalysts. The high stability of our photocathodes should be important for the practical application of these devices for solar fuel production.

  10. Phonon bottleneck in p-type Ge/Si quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yakimov, A. I., E-mail: yakimov@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Tomsk State University, 634050 Tomsk (Russian Federation); Kirienko, V. V.; Armbrister, V. A. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Bloshkin, A. A.; Dvurechenskii, A. V. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2015-11-23

    We study the effect of quantum dot size on the mid-infrared photo- and dark current, photoconductive gain, and hole capture probability in ten-period p-type Ge/Si quantum dot heterostructures. The dot dimensions are varied by changing the Ge coverage and the growth temperature during molecular beam epitaxy of Ge/Si(001) system in the Stranski-Krastanov growth mode. In all samples, we observed the general tendency: with decreasing the size of the dots, the dark current and hole capture probability are reduced, while the photoconductive gain and photoresponse are enhanced. Suppression of the hole capture probability in small-sized quantum dots is attributed to a quenched electron-phonon scattering due to phonon bottleneck.

  11. Improved performance of P-type DSCs with a compact blocking layer coated by different thicknesses

    Science.gov (United States)

    Ho, Phuong; Bao, Le Quoc; Cheruku, Rajesh; Kim, Jae Hong

    2016-09-01

    The introduction of different thicknesses of a compact NiO blocking layer coating with different spin speeds on FTO and followed by a coating of photoactive NiO electrode for p-type dye-sensitized solar cells ( p-DSCs). This study examined the fabrication of a compact NiO blocking layer by decomposing an ethanolic precursor solution of nickel acetate tetrahydrate. The DCBZ dye used as the photosensitizer for the NiO electrode in the p-DSCs device and their performances have been analyzed. The enhancement of photovoltaic performance and resulted from an increase in the power conversion efficiency ( η). The electrochemical impedance spectroscopy (EIS) measurement demonstrated that charge recombination was suppressed when a compact NiO blocking layer was applied. The results showed that the best p-DSC was achieved by employing 3000 rpm spin-coated process for different times of blocking layer.

  12. Ge-intercalated graphene: The origin of the p-type to n-type transition

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-09-01

    Recently huge interest has been focussed on Ge-intercalated graphene. In order to address the effect of Ge on the electronic structure, we study Ge-intercalated free-standing C 6 and C 8 bilayer graphene, bulk C 6Ge and C 8Ge, as well as Ge-intercalated graphene on a SiC(0001) substrate, by density functional theory. In the presence of SiC(0001), there are three ways to obtain n-type graphene: i) intercalation between C layers; ii) intercalation at the interface to the substrate in combination with Ge deposition on the surface; and iii) cluster intercalation. All other configurations under study result in p-type states irrespective of the Ge coverage. We explain the origin of the different doping states and establish the conditions under which a transition occurs. © Copyright EPLA, 2012.

  13. Nanopore formation on low-doped p-type silicon under illumination

    Energy Technology Data Exchange (ETDEWEB)

    Chiboub, N. [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria); Chazalviel, J.-N.; Ozanam, F. [Physique de la Matiere Condensee, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Moulay, S. [Universite Saad Dahleby, B.P. 270, Route de Soumaa, Blida (Algeria); Manseri, A. [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria)

    2010-04-01

    Porous silicon layers were elaborated by anodization of highly resistive p-type silicon in HF/ethylene glycol solution under front side illumination, as a function of etching time, HF concentration and illumination intensity. The porous layer morphology was investigated by scanning electron microscopy (SEM). The illumination during anodization was provided by a tungsten lamp or lasers of different wavelengths. Under anodization, a microporous layer is formed up to a critical thickness above which macropores appear. Under illumination, the instability limiting the growth of the microporous layer occurs at a critical thickness much larger than in the dark. This critical thickness depends on HF concentration, illumination wavelength and intensity. These non-trivial dependencies are rationalized in a model in which photochemical etching in the electrochemically formed porous layer plays the central role.

  14. Empirical model predicting the layer thickness and porosity of p-type mesoporous silicon

    Science.gov (United States)

    Wolter, Sascha J.; Geisler, Dennis; Hensen, Jan; Köntges, Marc; Kajari-Schröder, Sarah; Bahnemann, Detlef W.; Brendel, Rolf

    2017-04-01

    Porous silicon is a promising material for a wide range of applications because of its versatile layer properties and the convenient preparation by electrochemical etching. Nevertheless, the quantitative dependency of the layer thickness and porosity on the etching process parameters is yet unknown. We have developed an empirical model to predict the porosity and layer thickness of p-type mesoporous silicon prepared by electrochemical etching. The impact of the process parameters such as current density, etching time and concentration of hydrogen fluoride is evaluated by ellipsometry. The main influences on the porosity of the porous silicon are the current density, the etching time and their product while the etch rate is dominated by the current density, the concentration of hydrogen fluoride and their product. The developed model predicts the resulting layer properties of a certain porosification process and can, for example be used to enhance the utilization of the employed chemicals.

  15. Membrane Anchoring and Ion-Entry Dynamics in P-type ATPase Copper Transport

    DEFF Research Database (Denmark)

    Grønberg, Christina; Sitsel, Oleg; Lindahl, Erik

    2016-01-01

    Cu(+)-specific P-type ATPase membrane protein transporters regulate cellular copper levels. The lack of crystal structures in Cu(+)-binding states has limited our understanding of how ion entry and binding are achieved. Here, we characterize the molecular basis of Cu(+) entry using molecular......-dynamics simulations, structural modeling, and in vitro and in vivo functional assays. Protein structural rearrangements resulting in the exposure of positive charges to bulk solvent rather than to lipid phosphates indicate a direct molecular role of the putative docking platform in Cu(+) delivery. Mutational analyses...... and simulations in the presence and absence of Cu(+) predict that the ion-entry path involves two ion-binding sites: one transient Met148-Cys382 site and one intramembranous site formed by trigonal coordination to Cys384, Asn689, and Met717. The results reconcile earlier biochemical and x-ray absorption data...

  16. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  17. Bulk and Surface Event Identification in p-type Germanium Detectors

    CERN Document Server

    Yang, L T; Jia, L P; Jiang, H; Li, J; Lin, F K; Lin, S T; Liu, S K; Ma, J L; Sharma, V; Singh, L; Singh, M K; Soma, A K; Yang, S W; Wang, L; Wang, Q; Wong, H T; Yue, Q; Zhao, W

    2016-01-01

    The p-type point-contact germanium detectors, due to its sub-keV sensitivities and low internal radioactivity background, are demonstrated to be competitive tools for light dark matter WIMPs searches and may have potential applications in neutrino physics. These detectors exhibit anomalous surface behavior, which has been characterized and dealt with in previous analysis. However, the analysis method rely on spectral shape assumptions and must use external calibration sources. In this report, we purpose an improved method, where in situ data could be used as calibration sources. Data from CDEX-1 and TEXONO experiments will be re-examined and the results are shown to be consistent with both analysis.

  18. Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs

    Science.gov (United States)

    Bioud, Youcef A.; Boucherif, Abderraouf; Belarouci, Ali; Paradis, Etienne; Drouin, Dominique; Arès, Richard

    2016-10-01

    We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.

  19. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-01-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design. PMID:28145438

  20. Luminescence properties of p-type thin CdS films prepared by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Ullrich, B. [Tokyo Univ. (Japan). Dept. of Physics; Ezumi, H. [Department of Electrical Engineering, Hiroshima-Denki Institute of Technology, Hiroshima 739-03 (Japan); Keitoku, S. [Hiroshima Women`s University, Hiroshima 734 (Japan); Kobayashi, T. [Tokyo Univ. (Japan). Dept. of Physics

    1995-12-01

    Investigations of the luminescence of p-type CdS:Cu thin (less than or equal to 2 {mu}m) films on glass substrate prepared by laser ablation were performed for the first time. The dependences of the luminescence on the Cu content in the thin films were studied at 300 K with argon laser lines at 457.9 nm, 488.0 nm and 514.5 nm. It is demonstrated that the luminescence excited with the 514.5 nm line corresponds to the donor-acceptor transition. Furthermore, it is shown that the intensity of the red emission of CdS:Cu films can be efficiently bleached by Cu doping. (orig.)

  1. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors.

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L; Hersam, Mark C; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  2. Asymptotics of the trap-dominated Gunn effect in p-type Ge

    Science.gov (United States)

    Bonilla, L. L.; Hernando, P. J.; Herrero, M. A.; Kindelan, M.; Velázquez, J. J. L.

    1997-09-01

    We present an asymptotic analysis of the Gunn effect in a drift-diffusion model - including electric-field-dependent generation-recombination processes - for long samples of strongly compensated p-type Ge at low temperature and under d.c. voltage bias. During each Gunn oscillation, there are different stages corresponding to the generation, motion and annihilation of solitary waves. Each stage may be described by one evolution equation for only one degree of freedom (the current density), except for the generation of each new wave. The wave generation is a faster process that may be described by solving a semiinfinite canonical problem. As a result of our study we have found that (depending on the boundary condition) one or several solitary waves may be shed during each period of the oscillation. Examples of numerical simulations validating our analysis are included.

  3. DLTS of p-type Czochralski Si wafers containing processing-induced macropores

    Science.gov (United States)

    Simoen, E.; Depauw, V.; Gordon, I.; Poortmans, J.

    2012-01-01

    The deep levels present in p-type Czochralski silicon with processing-induced macropores in the depletion region have been studied by the deep-level transient (DLT) spectroscopy technique. It is shown that a broad band is present for a bias pulse close to the interface with the Al Schottky contact, which exhibits anomalously slow hole capture and is ascribed to the internal interface states of the macropores. For depths beyond the pore region, other deep levels, associated with point defects—possibly metal contamination during the high-temperature annealing step under H2 ambient--have been observed. The impact of the observed defects on the lifetime of thin-film solar cells, fabricated using macropore-based layer transfer is discussed. Finally, it is shown that the presence of pores in the depletion region, which also affects the DLT-spectrum, alters the capacitance-voltage characteristics.

  4. Large area growth and electrical properties of p-type WSe2 atomic layers.

    Science.gov (United States)

    Zhou, Hailong; Wang, Chen; Shaw, Jonathan C; Cheng, Rui; Chen, Yu; Huang, Xiaoqing; Liu, Yuan; Weiss, Nathan O; Lin, Zhaoyang; Huang, Yu; Duan, Xiangfeng

    2015-01-14

    Transition metal dichacogenides represent a unique class of two-dimensional layered materials that can be exfoliated into single or few atomic layers. Tungsten diselenide (WSe(2)) is one typical example with p-type semiconductor characteristics. Bulk WSe(2) has an indirect band gap (∼ 1.2 eV), which transits into a direct band gap (∼ 1.65 eV) in monolayers. Monolayer WSe(2), therefore, is of considerable interest as a new electronic material for functional electronics and optoelectronics. However, the controllable synthesis of large-area WSe(2) atomic layers remains a challenge. The studies on WSe(2) are largely limited by relatively small lateral size of exfoliated flakes and poor yield, which has significantly restricted the large-scale applications of the WSe(2) atomic layers. Here, we report a systematic study of chemical vapor deposition approach for large area growth of atomically thin WSe(2) film with the lateral dimensions up to ∼ 1 cm(2). Microphotoluminescence mapping indicates distinct layer dependent efficiency. The monolayer area exhibits much stronger light emission than bilayer or multilayers, consistent with the expected transition to direct band gap in the monolayer limit. The transmission electron microscopy studies demonstrate excellent crystalline quality of the atomically thin WSe(2). Electrical transport studies further show that the p-type WSe(2) field-effect transistors exhibit excellent electronic characteristics with effective hole carrier mobility up to 100 cm(2) V(-1) s(-1) for monolayer and up to 350 cm(2) V(-1) s(-1) for few-layer materials at room temperature, comparable or well above that of previously reported mobility values for the synthetic WSe(2) and comparable to the best exfoliated materials.

  5. Improvement in the Photocurrent of Inverted Organic Solar Cells Using MoO(x)-Doped TAPC as a P-Type Optical Spacer.

    Science.gov (United States)

    Song, Jiyun; Song, Hyung-Jun; Kim, Jun Young; Lee, Yeonkyung; Park, Myeongjin; Kwon, Yongwon; Ko, Youngjun; Lee, Changhee

    2016-05-01

    In this work, we demonstrate enhancement in the short-circuit current of inverted organic photovoltaic cells (OPVs) using a p-type optical spacer. The p-type optical spacer, which consists of molybdenum oxide (MoO(x))-doped 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), shows improved transmittance at visible light with high electrical conductivity. The electrical field distribution of incident light at the active layer of OPVs can be controlled by tuning the thickness of the optical spacer in the OPVs. Specifically, the incorporation of the 20-nm optical spacer layer in the OPV leads to enhanced spectral response of the device in the wavelength range of 400-600 nm, which is consistent with the combined results of improved optical absorption and better charge transport characteristics. As a result, the OPV with a 20-nm p-type optical spacer shows improvement in the short-circuit current compared with a device with 10 nm of embedded MoO(x).

  6. Improvement in thermoelectric power factor of mechanically alloyed p-type SiGe by incorporation of TiB2

    Science.gov (United States)

    Ahmad, Sajid; Dubey, K.; Bhattacharya, Shovit; Basu, Ranita; Bhatt, Ranu; Bohra, A. K.; Singh, Ajay; Aswal, D. K.; Gupta, S. K.

    2016-05-01

    Nearly 60% of the world's useful energy is wasted as heat and recovering a fraction of this waste heat by converting it as useful electrical power is an important area of research[1]. Thermoelectric power generators (TEG) are solid state devices which converts heat into electricity. TEG consists of n and p-type thermoelements connected electrically in series and thermally in parallel[2]. Silicon germanium (SiGe) alloy is one of the conventional high temperature thermoelectric materials and is being used in radio-isotopes based thermoelectric power generators for deep space exploration programs.Temperature (T) dependence of thermoelectric (TE) properties of p-type SiGe and p-type SiGe-x wt.%TiB2 (x=6,8,10%) nanocomposite materials has been studied with in the temperature range of 300 K to 1100 K. It is observed that there is an improvement in the power factor (α2/ρ) of SiGe alloy on addition of TiB2 upto 8 wt.% that is mainly due to increase in the Seebeck coefficient (α) and electrical conductivity (σ) of the alloy.

  7. Preparation of p-type NiO films by reactive sputtering and their application to CdTe solar cells

    Science.gov (United States)

    Ishikawa, Ryousuke; Furuya, Yasuaki; Araki, Ryouichi; Nomoto, Takahiro; Ogawa, Yohei; Hosono, Aikyo; Okamoto, Tamotsu; Tsuboi, Nozomu

    2016-02-01

    Transparent p-type NiO films were prepared by reactive sputtering using the facing-target system under Ar-diluted O2 gas at Tsub of 30 and 200 °C. The increasing intensity of dominant X-ray diffraction (XRD) peaks indicates improvements in the crystallinity of NiO films upon Cu doping. In spite of the crystallographic and optical changes after Cu-doping, the electrical properties of Cu-doped NiO films were slightly improved. Upon Ag-doping at 30 °C under low O2 concentration, on the other hand, the intensity of the dominant (111) XRD peaks was suppressed and p-type conductivity increased from ˜10-3 to ˜10-1 S cm-1. Finally, our Ag-doped NiO films were applied as the back contact of CdTe solar cells. CdTe solar cells with a glass/ITO/CdS/CdTe/NiO structure exhibited an efficiency of 6.4%, suggesting the high potential of using p-type NiO for the back-contact film in thin-film solar cells.

  8. Improvement in thermoelectric power factor of mechanically alloyed p-type SiGe by incorporation of TiB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Sajid, E-mail: sajidahmadiitkgp@gmail.com [Nuclear Research Laboratory, Astrophysical Sciences Division, B.A.R.C., Zakura, Srinagar, Kashmir-190024 (India); Dubey, K. [Barkatullah University, Bhopal–462026 (India); Bhattacharya, Shovit; Basu, Ranita; Bhatt, Ranu; Bohra, A. K.; Singh, Ajay; Aswal, D. K.; Gupta, S. K. [Technical Physics Division, B.A.R.C., Trombay, Mumbai – 400085 (India)

    2016-05-23

    Nearly 60% of the world’s useful energy is wasted as heat and recovering a fraction of this waste heat by converting it as useful electrical power is an important area of research{sup [1]}. Thermoelectric power generators (TEG) are solid state devices which converts heat into electricity. TEG consists of n and p-type thermoelements connected electrically in series and thermally in parallel{sup [2]}. Silicon germanium (SiGe) alloy is one of the conventional high temperature thermoelectric materials and is being used in radio-isotopes based thermoelectric power generators for deep space exploration programs.Temperature (T) dependence of thermoelectric (TE) properties of p-type SiGe and p-type SiGe-x wt.%TiB{sub 2} (x=6,8,10%) nanocomposite materials has been studied with in the temperature range of 300 K to 1100 K. It is observed that there is an improvement in the power factor (α{sup 2}/ρ) of SiGe alloy on addition of TiB{sub 2} upto 8 wt.% that is mainly due to increase in the Seebeck coefficient (α) and electrical conductivity (σ) of the alloy.

  9. P-type ZnO thin films prepared by in situ oxidation of DC sputtered Zn{sub 3}N{sub 2}:Ga

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jun; Xue Shuwen; Shao Lexi, E-mail: shaolxmail@163.co [School of Physical Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China)

    2010-04-15

    The feasibility of a new fabrication route for N and Ga codoped p-type ZnO thin films on glass substrates, consisting of DC sputtering deposition of Zn{sub 3}N{sub 2}:Ga precursors followed by in situ oxidation in high purity oxygen, has been studied. The effects of oxidation temperature on the structural, optical and electrical properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance and Hall effect measurements. The results were compared to a control film without Ga. XRD analyses revealed that the Zn{sub 3}N{sub 2} films entirely transformed into ZnO films after annealing Zn{sub 3}N{sub 2} films in oxygen over 500 {sup 0}C for 2 h. Hall effect measurements confirmed p-type conduction in N and Ga codoped ZnO films with a low resistivity of 19.8 {Omega} {center_dot} cm, a high hole concentration of 4.6 x 10{sup 18} cm{sup -3} and a Hall mobility of 0.7 cm{sup 2}/(V{center_dot}s). These results demonstrate a promising approach to fabricate low resistivity p-type ZnO with high hole concentration. (semiconductor materials)

  10. The Properties of Sprayed Nanostructured P-Type CuI Films for Dye-Sensitized Solar Cells Application

    Directory of Open Access Journals (Sweden)

    M. N. Amalina

    2012-01-01

    Full Text Available In our experiments, we provide a new approach for depositing CuI (inorganic compound thin films using the mister atomizer technique. The CuI solution was sprayed into fine droplets using argon as a carrier gas at different solution concentrations. The solution sprayed was 50 ml for all samples with substrate temperature constant at 50°C during the deposition process. The result shows that the CuI thin film properties strongly depend on its precursor concentration. The structural properties were characterized by XRD with strong (111 orientation shows for all the CuI thin films. FESEM images revealed that all the CuI thin films deposited were uniform with the existence of nanostructured CuI particle. The EDX measurement confirms the existence of Cu:I in the films. The nanostructured CuI will improve the penetration of p-type between the mesoporous matrix of TiO2 thin film. Promising conductivity value of about 10° S cm−1 was obtained for CuI thin films deposited by this new deposition method. Low transmittance of below 50% was observed for all CuI thin films. The band gap energy obtained here was between 2.82 eV and 2.92 eV which is much smaller than the reported band gap which is 3.1 eV.

  11. Electrical Detection of the Helical Spin Texture in a p-type Topological Insulator Sb2Te3

    Science.gov (United States)

    Li, C. H.; van ‘T Erve, O. M. J.; Li, Y. Y.; Li, L.; Jonker, B. T.

    2016-07-01

    The surface states of 3D topological insulators (TIs) exhibit a helical spin texture with spin locked at right angles with momentum. The chirality of this spin texture is expected to invert crossing the Dirac point, a property that has been experimentally observed by optical probes. Here, we directly determine the chirality below the Dirac point by electrically detecting spin-momentum locking in surface states of a p-type TI, Sb2Te3. A current flowing in the Sb2Te3 surface states generates a net spin polarization due to spin-momentum locking, which is electrically detected as a voltage on an Fe/Al2O3 tunnel barrier detector. Measurements of this voltage as a function of current direction and detector magnetization indicate that hole spin-momentum locking follows the right-hand rule, opposite that of electron, providing direct confirmation that the chirality is indeed inverted below Dirac point. The spin signal is linear with current, and exhibits a temperature dependence consistent with the semiconducting nature of the TI film and freeze-out of bulk conduction below 100 K. Our results demonstrate that the chirality of the helical spin texture of TI surface states can be determined electrically, an enabling step in the electrical manipulation of spins in next generation TI-based quantum devices.

  12. High hole mobility p-type GaN with low residual hydrogen concentration prepared by pulsed sputtering

    Science.gov (United States)

    Arakawa, Yasuaki; Ueno, Kohei; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-08-01

    We have grown Mg-doped GaN films with low residual hydrogen concentration using a low-temperature pulsed sputtering deposition (PSD) process. The growth system is inherently hydrogen-free, allowing us to obtain high-purity Mg-doped GaN films with residual hydrogen concentrations below 5 × 1016 cm-3, which is the detection limit of secondary ion mass spectroscopy. In the Mg profile, no memory effect or serious dopant diffusion was detected. The as-deposited Mg-doped GaN films showed clear p-type conductivity at room temperature (RT) without thermal activation. The GaN film doped with a low concentration of Mg (7.9 × 1017 cm-3) deposited by PSD showed hole mobilities of 34 and 62 cm2 V-1 s-1 at RT and 175 K, respectively, which are as high as those of films grown by a state-of-the-art metal-organic chemical vapor deposition apparatus. These results indicate that PSD is a powerful tool for the fabrication of GaN-based vertical power devices.

  13. Ultrafast Dynamics of Hole Injection and Recombination in Organometal Halide Perovskite Using Nickel Oxide as p-Type Contact Electrode.

    Science.gov (United States)

    Corani, Alice; Li, Ming-Hsien; Shen, Po-Shen; Chen, Peter; Guo, Tzung-Fang; El Nahhas, Amal; Zheng, Kaibo; Yartsev, Arkady; Sundström, Villy; Ponseca, Carlito S

    2016-04-01

    There is a mounting effort to use nickel oxide (NiO) as p-type selective electrode for organometal halide perovskite-based solar cells. Recently, an overall power conversion efficiency using this hole acceptor has reached 18%. However, ultrafast spectroscopic investigations on the mechanism of charge injection as well as recombination dynamics have yet to be studied and understood. Using time-resolved terahertz spectroscopy, we show that hole transfer is complete on the subpicosecond time scale, driven by the favorable band alignment between the valence bands of perovskite and NiO nanoparticles (NiO(np)). Recombination time between holes injected into NiO(np) and mobile electrons in the perovskite material is shown to be hundreds of picoseconds to a few nanoseconds. Because of the low conductivity of NiO(np), holes are pinned at the interface, and it is electrons that determine the recombination rate. This recombination competes with charge collection and therefore must be minimized. Doping NiO to promote higher mobility of holes is desirable in order to prevent back recombination.

  14. A study of structural, electrical, and optical properties of p-type Zn-doped SnO2 films versus deposition and annealing temperature

    Science.gov (United States)

    Le, Tran; Phuc Dang, Huu; Luc, Quang Ho; Hieu Le, Van

    2017-04-01

    This study presents a detailed investigation of the structural, electrical, and optical properties of p-type Zn-doped SnO2 versus the deposition and annealing temperature. Using a direct-current (DC) magnetron sputtering method, p-type transparent conductive Zn-doped SnO2 (ZTO) films were deposited on quartz glass substrates. Zn dopants incorporated into the SnO2 host lattice formed the preferred dominant SnO2 (1 0 1) and (2 1 1) planes. X-ray photoelectron spectroscopy (XPS) was used for identifying the valence state of Zn in the ZTO film. The electrical property of ZTO films changed from n-type to p-type at the threshold temperature of 400 °C, and the films achieved extremely high conductivity at the optimum annealing temperature of 600 °C after annealing for 2 h. The best conductive property of the film was obtained on a 10 wt% ZnO-doped SnO2 target with a resistivity, hole concentration, and hole mobility of 0.22 Ω · cm, 7.19  ×  1018 cm-3, and 3.95 cm2 V-1 s-1, respectively. Besides, the average transmission of films was  >84%. The surface morphology of films was examined using scanning electron microscopy (SEM). Moreover, the acceptor level of Zn2+ was identified using photoluminescence spectra at room temperature. Current-voltage (I-V) characteristics revealed the behavior of a p-ZTO/n-Si heterojunction diode.

  15. Ambipolar Organic Phototransistors with p-Type/n-Type Conjugated Polymer Bulk Heterojunction Light-Sensing Layers

    KAUST Repository

    Nam, Sungho

    2016-11-18

    Ambipolar organic phototransistors with sensing channel layers, featuring p-type and n-type conjugated polymer bulk heterojunctions, exhibit outstanding light-sensing characteristics in both p-channel and n-channel sensing operation modes.

  16. Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, Vidya, E-mail: vj1510@yahoo.com

    2015-09-01

    Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide crystal have been reported. Single crystal, 1 0 0〉 orientations and ∼500 μm thick p-type GaSb samples with carrier concentration of 3.30 × 10{sup 17} cm{sup −3} were irradiated at 100 MeV Fe{sup 7+} ions. We have used 15UD Pelletron facilities at IUAC with varying fluences of 5 × 10{sup 10}–1 × 10{sup 14} ions cm{sup −2}. The effects of irradiation on these samples have been investigated using, spectroscopic ellipsometry, atomic force microscopy and ultraviolet–visible–NIR spectroscopy techniques. Ellipsometry parameters, psi (Ψ) and delta (Δ) for the unirradiated sample and samples irradiated with different fluences were recorded. The data were fit to a three phase model to determine the refractive index and extinction coefficient. The refractive index and extinction coefficient for various fluences in ultraviolet, visible, and infrared, regimes were evaluated. Atomic force microscopy has been used to study these surface modifications. In order to have more statistical information about the surface, we have plotted the height structure histogram for all the samples. For unirradiated sample, we observed the Gaussian fitting. This result indicates the more ordered height structure symmetry. Whereas for the sample irradiated with the fluence of 1 × 10{sup 13}, 5 × 10{sup 13} and 1 × 10{sup 14} ions cm{sup −2}, we observed the scattered data. The width of the histogram for samples irradiated up to the fluence of 1 × 10{sup 13} ion cm{sup −2} was found to be almost same however it decreased at higher fluence. UV reflectance spectra of the sample irradiated with increasing fluences exhibit three peaks at 292, 500 and 617 nm represent the high energy GaSb; E{sub 1}, E{sub 1} + Δ and E{sub 2} band gaps in all irradiated samples.

  17. Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation.

    Science.gov (United States)

    Nipane, Ankur; Karmakar, Debjani; Kaushik, Naveen; Karande, Shruti; Lodha, Saurabh

    2016-02-23

    P-type doping of MoS2 has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS2. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS2. A wide range of nondegenerate to degenerate p-type doping is demonstrated in MoS2 field effect transistors exhibiting dominant hole transport. Nearly ideal and air stable, lateral homogeneous p-n junction diodes with a gate-tunable rectification ratio as high as 2 × 10(4) are demonstrated using area selective doping. Comparison of XPS data from unimplanted and implanted MoS2 layers shows a shift of 0.67 eV toward lower binding energies for Mo and S peaks indicating p-type doping. First-principles calculations using density functional theory techniques confirm p-type doping due to charge transfer originating from substitutional as well as physisorbed phosphorus in top few layers of MoS2. Pre-existing sulfur vacancies are shown to enhance the doping level significantly.

  18. High performance p-type NiOx thin-film transistor by Sn doping

    Science.gov (United States)

    Lin, Tengda; Li, Xiuling; Jang, Jin

    2016-06-01

    Major obstacles towards power efficient complementary electronics employing oxide thin-film transistors (TFTs) lie in the lack of equivalent well performing p-channel devices. Here, we report a significant performance enhancement of solution-processed p-type nickel oxide (NiOx) TFTs by introducing Sn dopant. The Sn-doped NiOx (Sn-NiOx) TFTs annealed at 280 °C demonstrate substantially improved electrical performances with the increase in the on/off current ratio (Ion/Ioff) by ˜100 times, field-effect mobility (μlin) by ˜3 times, and the decrease in subthreshold swing by half, comparing with those of pristine NiOx TFTs. X-ray photoelectron spectroscopy and X-ray diffraction results confirm that Sn atoms tend to substitute Ni sites and induce more amorphous phase. A decrease in density of states in the gap of NiOx by Sn doping and the shift of Fermi level (EF) into the midgap lead to the improvements of TFT performances. As a result, Sn-NiOx can be a promising material for the next-generation, oxide-based electronics.

  19. p-Type CuYO{sub 2} as hydrogen photocathode

    Energy Technology Data Exchange (ETDEWEB)

    Trari, M.; Bouguelia, A.; Bessekhouad, Y. [Laboratoire de Stockage et de Valorisation des Energies Renouvelables, BP 32 El-Alia 16311, Algiers (Algeria)

    2006-01-23

    A new photochemical system based on a CuYO{sub 2} dispersion in aqueous S{sup 2-} or SO{sub 3}{sup 2-} solution as hole scavengers is proposed. The delafossite CuYO{sub 2}, doped with calcium, is a low p-type semiconductor with a hole mobility of 7.3x10{sup -7}m{sup 2}V{sup -1}s{sup -1}. The band gap is 3.50eV and the transition is directly allowed. The valence band edge, located at 5.23eV below vacuum, is made up from Cu-3d type typical of delafossite oxides. The flat band potential V{sub fb} (+0.17V{sub sce}) lies below the H{sub 2}O/H{sub 2} potential permitting a spontaneous H{sub 2}-formation under band gap illumination in aqueous S{sup 2-} or SO{sub 3}{sup 2-} electrolytes. p-CuYO{sub 2} loaded with n-Cu{sub 2}O exhibited a higher performance with a H{sub 2} evolution rate of 0.4cm{sup 3}h{sup -1} in 0.1MS{sup 2-} (pH 13.4). The decrease of photoactivity over time is due to the formation of yellow polysulfides S{sub n}{sup 2-} which compete with H{sub 2}O in the reduction process. (author)

  20. Robust p-type doping of copper oxide using nitrogen implantation

    Science.gov (United States)

    Jorge, Marina; Polyakov, Stanislav M.; Cooil, Simon; Schenk, Alex K.; Edmonds, Mark; Thomsen, Lars; Mazzola, Federico; Wells, Justin W.

    2017-07-01

    We demonstrate robust p-type doping of Cu2O using low/medium energy ion implantation. Samples are made by controlled oxidation of annealed Cu metal foils, which results in Cu2O with levels of doping close to intrinsic. Samples are then implanted with nitrogen ions using a kinetic energy in the few keV range. Using this method, we are able to produce very high levels of doping, as evidenced by a 350 meV shift in the Fermi level towards the VB maximum. The robustness of the nitrogen implanted samples are tested by exposing them to atmospheric contaminants, and elevated temperatures. The samples are found to survive an increase in temperature of many hundreds of degrees. The robustness of the samples, combined with the fact that the materials used are safe, abundant and non-toxic and that the methods used for the growth of Cu2O and N+ implantation are simple and cheap to implement industrially, underlines the potential of Cu2O:N for affordable intermediate band photovoltaics.

  1. Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes.

    Science.gov (United States)

    Roques, Magali; Wall, Richard J; Douglass, Alexander P; Ramaprasad, Abhinay; Ferguson, David J P; Kaindama, Mbinda L; Brusini, Lorenzo; Joshi, Nimitray; Rchiad, Zineb; Brady, Declan; Guttery, David S; Wheatley, Sally P; Yamano, Hiroyuki; Holder, Anthony A; Pain, Arnab; Wickstead, Bill; Tewari, Rita

    2015-11-01

    Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei.

  2. Design of P-Type Cladding Layers for Tunnel-Injected UVA Light Emitting Diodes

    CERN Document Server

    Zhang, Yuewei; Akyol, Fatih; Allerman, Andrew A; Moseley, Michael W; Armstrong, Andrew M; Rajan, Siddharth

    2016-01-01

    We discuss the engineering of p-AlGaN cladding layers for achieving efficient tunnel-injected III-Nitride ultraviolet light emitting diodes (UV LEDs) in the UV-A spectral range. We show that capacitance-voltage measurements can be used to estimate the compensation and doping in p-AlGaN layers located between the multi-quantum well region and the tunnel junction layer. By increasing the p-type doping concentration to overcome the background compensation, on-wafer external quantum efficiency and wall-plug efficiency of 3.37% and 1.62% were achieved for tunnel-injected UV LEDs emitting at 325 nm. We also show that interband tunneling hole injection can be used to realize UV LEDs without any acceptor doping. The work discussed here provides new understanding of hole doping and transport in AlGaN-based UV LEDs, and demonstrates the excellent performance of tunnel-injected LEDs for the UV-A wavelength range.

  3. P-type Planet–Planet Scattering: Kepler Close Binary Configurations

    Science.gov (United States)

    Gong, Yan-Xiang

    2017-01-01

    A hydrodynamical simulation shows that a circumbinary planet will migrate inward to the edge of the disk cavity. If multiple planets form in a circumbinary disk, successive migration will lead to planet–planet scattering (PPS). PPS of Kepler-like circumbinary planets is discussed in this paper. The aim of this paper is to answer how PPS affects the formation of these planets. We find that a close binary has a significant influence on the scattering process. If PPS occurs near the unstable boundary of a binary, about 10% of the systems can be completely destroyed after PPS. In more than 90% of the systems, there is only one planet left. Unlike the eccentricity distribution produced by PPS in a single star system, the surviving planets generally have low eccentricities if PPS take place near the location of the currently found circumbinary planets. In addition, the ejected planets are generally the innermost of two initial planets. The above results depend on the initial positions of the two planets. If the initial positions of the planets are moved away from the binary, the evolution tends toward statistics similar to those around single stars. In this process, the competition between the planet–planet force and the planet-binary force makes the eccentricity distribution of surviving planets diverse. These new features of P-type PPS will deepen our understanding of the formation of these circumbinary planets.

  4. TSC measurements on proton-irradiated p-type Si-sensors

    Energy Technology Data Exchange (ETDEWEB)

    Donegani, Elena; Fretwurst, Eckhart; Garutti, Erika; Junkes, Alexandra [University of Hamburg (Germany)

    2016-07-01

    Thin n{sup +}p Si sensors are potential candidates for coping with neutron equivalent fluences up to 2.10{sup 16} n{sub eq}/cm{sup 2} and an ionizing dose in the order of a few MGy, which are expected e.g. for the HL-LHC upgrade. The aim of the present work is to provide experimental data on radiation-induced defects in order to: firstly, get a deeper understanding of the properties of hadron induced defects, and secondly develop a radiation damage model based on microscopic measurements. Therefore, the outcomes of Thermally Stimulated Current measurements on 200 μm thick Float-Zone (FZ) and Magnetic Czochralski (MCz) diodes will be shown, as a results of irradiation with 23 MeV protons and isothermal annealing. The samples were irradiated in the fluence range (0.3-1).10{sup 14} n{sub eq}/cm{sup 2}, so that the maximal temperature at which the TSC signal is still sharply distinguishable from the dark current is 200 K. In particular, special focus will be given to the defect introduction rate and to the issue of boron removal in p-type silicon. Annealing studies allow to distinguish which defects mainly contribute to the leakage current and which to the space charge, and thus correlate microscopic defects properties with macroscopic sensor properties.

  5. Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes

    KAUST Repository

    Roques, Magali

    2015-11-13

    Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei.

  6. p-Type hydrogen sensing with Al- and V-doped TiO2 nanostructures

    Science.gov (United States)

    Li, Zhaohui; Ding, Dongyan; Ning, Congqin

    2013-01-01

    Doping with other elements is one of the efficient ways to modify the physical and chemical properties of TiO2 nanomaterials. In the present work, anatase TiO2 nanofilms doped with Al and V elements were fabricated through anodic oxidation of Ti6Al4V alloy and further annealing treatment. Hydrogen sensing behavior of the crystallized Ti-Al-V-O nanofilms at various working temperatures was investigated through exposure to 1,000 ppm H2. Different from n-type hydrogen sensing characteristics of undoped TiO2 nanotubes, the Al- and V-doped nanofilms presented a p-type hydrogen sensing behavior by showing increased resistance upon exposure to the hydrogen-containing atmosphere. The Ti-Al-V-O nanofilm annealed at 450°C was mainly composed of anatase phase, which was sensitive to hydrogen-containing atmosphere only at elevated temperatures. Annealing of the Ti-Al-V-O nanofilm at 550°C could increase the content of anatase phase in the oxide nanofilm and thus resulted in a good sensitivity and resistance recovery at both room temperature and elevated temperatures. The TiO2 nanofilms doped with Al and V elements shows great potential for use as a robust semiconducting hydrogen sensor.

  7. Evidence for an iron-hydrogen complex in p-type silicon

    Science.gov (United States)

    Leonard, S.; Markevich, V. P.; Peaker, A. R.; Hamilton, B.; Murphy, J. D.

    2015-07-01

    Interactions of hydrogen with iron have been studied in Fe contaminated p-type Czochralski silicon using capacitance-voltage profiling and deep level transient spectroscopy (DLTS). Hydrogen has been introduced into the samples from a silicon nitride layer grown by plasma enhanced chemical vapor deposition. After annealing of the Schottky diodes on Si:Fe + H samples under reverse bias in the temperature range of 90-120 °C, a trap has been observed in the DLTS spectra which we have assigned to a Fe-H complex. The trap is only observed when a high concentration of hydrogen is present in the near surface region. The trap concentration is higher in samples with a higher concentration of single interstitial Fe atoms. The defect has a deep donor level at Ev + 0.31 eV. Direct measurements of capture cross section of holes have shown that the capture cross section is not temperature dependent and its value is 5.2 × 10-17 cm2. It is found from an isochronal annealing study that the Fe-H complex is not very stable and can be eliminated completely by annealing for 30 min at 125 °C.

  8. Ferromagnetic ordering of Cr and Fe doped p-type diamond: An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Benecha, E. M. [Department of Physics, University of South Africa, P.O Box 392, UNISA 0003, Pretoria (South Africa); Lombardi, E. B. [College of Graduate Studies, University of South Africa, P.O Box 392, UNISA 0003, Pretoria (South Africa)

    2014-02-21

    Ferromagnetic ordering of transition metal dopants in semiconductors holds the prospect of combining the capabilities of semiconductors and magnetic systems in single hybrid devices for spintronic applications. Various semiconductors have so far been considered for spintronic applications, but low Curie temperatures have hindered room temperature applications. We report ab initio DFT calculations on the stability and magnetic properties of Fe and Cr impurities in diamond, and show that their ground state magnetic ordering and stabilization energies depend strongly on the charge state and type of co-doping. We predict that divacancy Cr{sup +2} and substitutional Fe{sup +1} order ferromagnetically in p-type diamond, with magnetic stabilization energies (and magnetic moment per impurity ion) of 16.9 meV (2.5 μ{sub B}) and 33.3 meV (1.0 μ{sub B}), respectively. These magnetic stabilization energies are much larger than what has been achieved in other semiconductors at comparable impurity concentrations, including the archetypal dilute magnetic semiconductor GaAs:Mn. In addition, substitutional Fe{sup +1} exhibits a strong half-metallic character, with the Fermi level crossing bands in only the spin down channel. These results, combined with diamond’s extreme properties, demonstrate that Cr or Fe dopedp-type diamond may successfully be considered in the search for room temperature spintronic materials.

  9. Results with p-type pixel sensors with different geometries for the HL-LHC

    Energy Technology Data Exchange (ETDEWEB)

    Allport, P.P. [Department of Physics, University of Liverpool, Oxford Road, Liverpool, L69 7ZE (United Kingdom); Bates, R.; Butter, C. [Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Casse, G. [Department of Physics, University of Liverpool, Oxford Road, Liverpool, L69 7ZE (United Kingdom); Dervan, P.J., E-mail: Paul.Dervan@cern.ch [Department of Physics, University of Liverpool, Oxford Road, Liverpool, L69 7ZE (United Kingdom); Forshaw, D.; Tsurin, I. [Department of Physics, University of Liverpool, Oxford Road, Liverpool, L69 7ZE (United Kingdom)

    2013-12-11

    Pixel detectors will be extensively used for the four innermost layers of the upgraded ATLAS experiment at the future High Luminosity LHC (HL-LHC) at CERN. The total area of pixel sensors will be over 5 m{sup 2}. The silicon sensors that will instrument the pixel volume will have to face several technology challenges. They will have to withstand doses up to 2×10{sup 16} n{sub eq}cm{sup −2}, to have a reduced inactive area at the edge of the sensors still being able to hold 1000 V bias voltage and to be relatively low cost considering the large area to be covered. N-side readout on p-type bulk is the most promising technology for satisfying the various requirements. Several sensor types have been produced in the UK, conceived for various readout systems, for studying the properties of n-in-p and n-in-n sensors before and after irradiation with test beam and laboratory measurements. The status of these studies is presented here.

  10. Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs

    Directory of Open Access Journals (Sweden)

    Hong Yu

    2009-04-01

    Full Text Available In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics. A semi-classical ballistic FET model is then used to evaluate the ballistic current-voltage characteristics of SiNW FETs with and without strain. Our results presented here indicate that [110] is the optimum orientation for the p-type SiNW FETs and sensors. For the ultra-scaled 2.2 nm square SiNW, due to the limit of strong quantum confinement, the effect of the uniaxial stress on the magnitude of ballistic drive current is too small to be considered, except for the [100] orientation. However, for larger 5 nm square SiNW transistors with various transport orientations, the uniaxial tensile stress obviously alters the ballistic performance, while the uniaxial compressive stress slightly changes the ballistic hole current. Furthermore, the competition of injection velocity and carrier density related to the effective hole masses is found to play a critical role in determining the performance of the nanotransistors.

  11. High-Performance p-Type Black Phosphorus Transistor with Scandium Contact.

    Science.gov (United States)

    Li, Ling; Engel, Michael; Farmer, Damon B; Han, Shu-Jen; Wong, H-S Philip

    2016-04-26

    A record high current density of 580 μA/μm is achieved for long-channel, few-layer black phosphorus transistors with scandium contacts after 400 K vacuum annealing. The annealing effectively improves the on-state current and Ion/Ioff ratio by 1 order of magnitude and the subthreshold swing by ∼2.5×, whereas Al2O3 capping significantly degrades transistor performances, resulting in 5× lower on-state current and 3× lower Ion/Ioff ratio. The influences of moisture on black phosphorus metal contacts are elucidated by analyzing the hysteresis of 3-20 nm thick black phosphorus transistors with scandium and gold contacts under different conditions: as-fabricated, after vacuum annealing, and after Al2O3 capping. The optimal black phosphorus film thickness for transistors with scandium contacts is found to be ∼10 nm. Moreover, p-type performance is shown in all transistors with scandium contacts, suggesting that the Fermi level is pinned closer to the valence band regardless of the flake thickness.

  12. Extraction of interface state density and resistivity of suspended p-type silicon nanobridges

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiahong; Liu Qingquan; Ge Yixian; Gu Fang; Li Min; Mao Xiaoli; Cao Hongxia

    2013-01-01

    The evaluation of the influence of the bending deformation of silicon nanobridges on their electrical properties is crucial for sensing and actuating applications.A combined theory/experimental approach for determining the resistivity and the density of interface states of the bending silicon nanobridges is presented.The suspended p-type silicon nanobridge test structures were fabricated from silicon-on-insulator wafers by using a standard CMOS lithography and anisotropic wet etching release process.After that,we measured the resistance of a set of silicon nanobridges versus their length and width under different bias voltages.In conjunction with a theoretical model,we have finally extracted both the interface state density of and resistivity suspended silicon nanobridges under different bending deformations,and found that the resistivity of silicon nanobridges without bending was 9.45 mΩ·cm and the corresponding interface charge density was around 1.7445 × 1013 cm-2.The bending deformation due to the bias voltage slightly changed the resistivity of the silicon nanobridge,however,it significantly changed the distribution of interface state charges,which strongly depends on the intensity of the stress induced by bending deformation.

  13. Growth of antimony doped P-type zinc oxide nanowires for optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhong Lin; Pradel, Ken

    2016-09-27

    In a method of growing p-type nanowires, a nanowire growth solution of zinc nitrate (Zn(NO.sub.3).sub.2), hexamethylenetetramine (HMTA) and polyethylenemine (800 M.sub.w PEI) is prepared. A dopant solution to the growth solution, the dopant solution including an equal molar ration of sodium hydroxide (NaOH), glycolic acid (C.sub.2H.sub.4O.sub.3) and antimony acetate (Sb(CH.sub.3COO).sub.3) in water is prepared. The dopant solution and the growth solution combine to generate a resulting solution that includes antimony to zinc in a ratio of between 0.2% molar to 2.0% molar, the resulting solution having a top surface. An ammonia solution is added to the resulting solution. A ZnO seed layer is applied to a substrate and the substrate is placed into the top surface of the resulting solution with the ZnO seed layer facing downwardly for a predetermined time until Sb-doped ZnO nanowires having a length of at least 5 .mu.m have grown from the ZnO seed layer.

  14. Thermoelectric properties of p-type partially double-filled (Pr1- z Nd z ) y Fe4- x Co x Sb12 skutterudites

    Science.gov (United States)

    Shin, Dong-Kil; Kim, Il-Ho

    2016-09-01

    p-Type partially double-filled (Pr1- z Nd z ) y Fe4- x Co x Sb12 ( z = 0.25, 0.75, y = 0.8, 0.9, and x = 0, 0.5, 1.0) skutterudites were synthesized by encapsulated melting and annealing and consolidated by hot pressing. The effects of Pr/Nd partial double-filling and Co substitution for Fe (charge compensation) on the electronic transport and the thermoelectric properties of the skutterudites were examined. A few secondary phases such as marcasite FeSb2 were formed together with the skutterudite phase, but the formation was suppressed with increasing Co content. Unlike for complete filling with Pr/Nd, the (Pr,Nd)Sb2 phases were not formed by partial filling with Pr/Nd. Successful Pr/Nd double filling in the voids and Co substitution for Fe were confirmed because the lattice constant increased with increasing filling fraction and Pr/Nd ratio, and decreased with increasing Co content. The electrical conductivity slightly decreased with increasing temperature, showing degenerate semiconductor characteristics, while the Hall and the Seebeck coefficients showed positive signs, indicating that holes were the major carriers ( p-type conductions). The Seebeck coefficient increased due to a decrease in the carrier concentration with increasing Pr and Co contents while the electrical conductivity decreased. The lattice thermal conductivity decreased because phonon scattering was enhanced by Pr and Nd double filling, which led to low thermal conductivity, but partially double-filled specimens did not have a significant effect on the reduction of lattice thermal conductivity compared with the completely double-filled specimens. The maximum dimensionless figure of merit, ZT = 0.84, was obtained at 723 K for (Pr0.75Nd0.25)0.8Fe3CoSb12.

  15. P-type thin films transistors with solution-deposited lead sulfide films as semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo-Castillo, A.; Salas-Villasenor, A.; Mejia, I. [Department of Materials Science and Engineering, The University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Aguirre-Tostado, S. [Centro de Investigacion en Materiales Avanzados, S. C. Alianza Norte 202, Parque de Investigacion e Innovacion Tecnologica, Apodaca, Nuevo Leon, C.P. 666000 (Mexico); Gnade, B.E. [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Quevedo-Lopez, M.A., E-mail: mxq071000@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States)

    2012-01-31

    In this paper we demonstrate p-type thin film transistors fabricated with lead sulfide (PbS) as semiconductor deposited by chemical bath deposition methods. Crystallinity and morphology of the resulting PbS films were characterized using X-ray diffraction, atomic force microscopy and scanning electron microscopy. Devices were fabricated using photolithographic processes in a bottom gate configuration with Au as source and drain top contacts. Field effect mobility for as-fabricated devices was {approx} 0.09 cm{sup 2} V{sup -1} s{sup -1} whereas the mobility for devices annealed at 150 Degree-Sign C/h in forming gas increased up to {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Besides the thermal annealing, the entire fabrications process was maintained below 100 Degree-Sign C. The electrical performance of the PbS-thin film transistors was studied before and after the 150 Degree-Sign C anneal as well as a function of the PbS active layer thicknesses. - Highlights: Black-Right-Pointing-Pointer Thin film transistors with PbS as semiconductor deposited by chemical bath deposition. Black-Right-Pointing-Pointer Photolithography-based thin film transistors with PbS films at low temperatures. Black-Right-Pointing-Pointer Electron mobility for anneal-PbS devices of {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Black-Right-Pointing-Pointer Highest mobility reported in thin film transistors with PbS as the semiconductor.

  16. Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes.

    Directory of Open Access Journals (Sweden)

    Magali Roques

    2015-11-01

    Full Text Available Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs. Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites in host liver and red blood cells, and sporogony (producing sporozoites in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei.

  17. Electron spin relaxation in p-type GaAs quantum wells

    Science.gov (United States)

    Zhou, Y.; Jiang, J. H.; Wu, M. W.

    2009-11-01

    We investigate electron spin relaxation in p-type GaAs quantum wells from a fully microscopic kinetic spin Bloch equation approach, with all the relevant scatterings, such as electron-impurity, electron-phonon, electron-electron Coulomb, electron-hole Coulomb and electron-hole exchange (the Bir-Aronov-Pikus (BAP) mechanism) scatterings, explicitly included. Via this approach, we examine the relative importance of the D'yakonov-Perel' (DP) and BAP mechanisms in wide ranges of temperature, hole density, excitation density and impurity density, and present a phase-diagram-like picture showing the parameter regime where the DP or BAP mechanism is more important. It is discovered that in the impurity-free case the temperature regime where the BAP mechanism is more efficient than the DP one is around the hole Fermi temperature for high hole density, regardless of excitation density. However, in the high impurity density case with the impurity density identical to the hole density, this regime is roughly from the electron Fermi temperature to the hole Fermi temperature. Moreover, we predict that for the impurity-free case, in the regime where the DP mechanism dominates the spin relaxation at all temperatures, the temperature dependence of the spin relaxation time (SRT) presents a peak around the hole Fermi temperature, which originates from the electron-hole Coulomb scattering. We also predict that at low temperature, the hole-density dependence of the electron SRT exhibits a double-peak structure in the impurity-free case, whereas it shows first a peak and then a valley in the case of identical impurity and hole densities. These intriguing behaviors are due to the contribution from holes in high subbands.

  18. Fabrication and simulation of single crystal p-type Si nanowire using SOI technology

    Energy Technology Data Exchange (ETDEWEB)

    Dehzangi, Arash, E-mail: arashd53@hotmail.com [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Larki, Farhad [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Naseri, Mahmud G. [Department of Physics, Faculty of Science, Malayer University, Malayer, Hamedan (Iran, Islamic Republic of); Navasery, Manizheh [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Majlis, Burhanuddin Y.; Razip Wee, Mohd F. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Halimah, M.K. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Islam, Md. Shabiul; Md Ali, Sawal H. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Saion, Elias [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2015-04-15

    Highlights: • Single crystal silicon nanowire is fabricated on Si on insulator substrate, using atomic force microscope (AFM) nanolithography and KOH + IPA chemical wet etching. • Some of major parameters in fabrication process, such as writing speed and applied voltage along with KOH etching depth are investigated, and then the I–V characteristic of Si nanowires is measured. • For better understanding of the charge transmission through the nanowire, 3D-TCAD simulation is performed to simulate the Si nanowires with the same size of the fabricated ones, and variation of majority and minority carriers, hole quasi-Fermi level and generation/recombination rate are investigated. - Abstract: Si nanowires (SiNWs) as building blocks for nanostructured materials and nanoelectronics have attracted much attention due to their major role in device fabrication. In the present work a top-down fabrication approach as atomic force microscope (AFM) nanolithography was performed on Si on insulator (SOI) substrate to fabricate a single crystal p-type SiNW. To draw oxide patterns on top of the SOI substrate local anodic oxidation was carried out by AFM in contact mode. After the oxidation procedure, an optimized solution of 30 wt.% KOH with 10 vol.% IPA for wet etching at 63 °C was applied to extract the nanostructure. The fabricated SiNW had 70–85 nm full width at half maximum width, 90 nm thickness and 4 μm length. The SiNW was simulated using Sentaurus 3D software with the exact same size of the fabricated device. I–V characterization of the SiNW was measured and compared with simulation results. Using simulation results variation of carrier's concentrations, valence band edge energy and recombination generation rate for different applied voltage were investigated.

  19. Electronic Band Structure and New Magneto-transport Properties in p-type Semiconductor Medium-infrared HgTe / CdTe Superlattice

    Science.gov (United States)

    Nafidi, Ab.; EL Abidi, A.; El Kaaouachi, A.; Nafidi, Ah.

    2005-06-01

    We report here the band structure and new magneto-transport results for HgTe (56 Å) / CdTe (30 Å) superlattice grown by molecular beam epitaxy (MBE). The angular dependence of the transverse magnetoresistance follows the two-dimensional (2D) behaviour. At low temperature, the sample exhibits p type conductivity with a concentration of 1.84×1012 cm-2 and a Hall mobility of 8200 cm2/Vs. The observed Shubnikov-de Haas effect gives a carrier density of 1.80×1012 cm-2. The superlattice heavy holes dominate the conduction in plane with an effective mass of 0.297 m0 and Fermi energy (2D) of 14 meV. In intrinsic regime, the measured gap Eg = 190 meV agree well with calculated Eg(Γ, 300 K) =178 meV. The formalism used here predicts that the system is semiconductor, for our HgTe to CdTe thickness ratio d1/d2 = 1,87, when d2 < 140 Å. In our case, d2=30 Å and Eg (Γ, 4.2 K) = 111 meV. In spite of it, the sample exhibits the features typical of a p type semiconductor and is a medium-infrared detector (7 μm< λ< 11 μm).

  20. Study the Characteristic of P-Type Junction-Less Side Gate Silicon Nanowire Transistor Fabricated by Atomic Force Microscopy Lithography

    Directory of Open Access Journals (Sweden)

    Arash Dehzangi

    2011-01-01

    Full Text Available Problem statement: Nanotransistor now is one of the most promising fields in nanoelectronics in order to decrease the energy consuming and application to create developed programmable information processors. Most of Computing and communications companies invest hundreds of millions of dollars in research funds every year to develop smaller transistors. Approach: The Junction-less side gate silicon Nano-wire transistor has been fabricated by Atomic Force Microscopy (AFM and wet etching on p-type Silicon On Insulator (SOI wafer. Then, we checked the characteristic and conductance trend in this device regarding to semi-classical approach by Semiconductor Probe Analyser (SPA. Results: We observed in characteristic of the device directly proportionality of the negative gate voltage and Source-Drain current. In semi classical approach, negative Gate voltage decreased the energy States of the Nano-wire between the source and the drain. The graph for positive gate voltage plotted as well to check. In other hand, the conductance will be following characteristic due to varying the gate voltage under the different drain-source voltage. Conclusion: The channel energy states are supposed to locate between two electrochemical potentials of the contacts in order to transform the charge. For the p-type channel the transform of the carriers is located in valence band and changing the positive or negative gate voltage, making the valence band energy states out of or in the area between the electrochemical potentials of the contacts causing the current reduced or increased.

  1. 氧化锌材料p型掺杂研究进展%Recent Research on p-type Doping of ZnO

    Institute of Scientific and Technical Information of China (English)

    谭蜜; 张红; 李万俊; 秦国平; 阮海波; 孔春阳

    2016-01-01

    氧化锌(ZnO)是 II-VI 族直接带隙化合物半导体材料,室温下禁带宽度为3.37 eV,激子束缚能高达60 meV,是制造蓝紫外发光、探测以及激光器件的理想材料。高质量 n 型和 p 型 ZnO 以及同质 p-n 结的制备是实现器件化的关键。目前,n 型 ZnO 的制备技术已趋于成熟,但高质量稳定的 p 型 ZnO 的缺乏已成为制约其器件化的瓶颈。在过去的十余年里,通过国内外科研工作者的不懈努力,在理论和实验上都取得了显著的成果。本文主要概述了 ZnO 材料的 p 型掺杂、p 型导电机制以及 p-ZnO 基光电器件的研究进展,同时初步探索了 ZnO 材料 p 型导电稳定性问题。%Zinc oxide (ZnO),a typical direct wide bandgap (3.37 eV)semiconductor,has attracted an increasing interest tothe optoelectronics field.Its large exciton binding energy of 60 meV endows it with high radiative recom-bination efficiency,a unique advantage in light emitting and lasing devices.The fabrications of high quality n-and p-type ZnO as well as p-n junction are the key steps to realize these applications.although the techniques of fabri-cated n-type ZnO has been well developed,the reliable p type doping of the material remains a major challenge to optoelectronic applications,despitethe fact that p-doping of ZnO has been improved and that marked results in ex-periment and theory have been achieved during the past ten years.In this review,we examined the recent research progress in p-type doping of ZnO,including the p-type performance,the mechanism of p-type conduction,and p-ZnO based photoelectric devices,and so on.Moreover,based on the challenges of the current researches,we sum-marized the factors that may affect the p-type doping,especially the stability of p-type ZnO materials.

  2. Inorganic p-Type Semiconductors: Their Applications and Progress in Dye-Sensitized Solar Cells and Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Ming-Hsien Li

    2016-04-01

    Full Text Available Considering the increasing global demand for energy and the harmful ecological impact of conventional energy sources, it is obvious that development of clean and renewable energy is a necessity. Since the Sun is our only external energy source, harnessing its energy, which is clean, non-hazardous and infinite, satisfies the main objectives of all alternative energy strategies. With attractive features, i.e., good performance, low-cost potential, simple processibility, a wide range of applications from portable power generation to power-windows, photoelectrochemical solar cells like dye-sensitized solar cells (DSCs represent one of the promising methods for future large-scale power production directly from sunlight. While the sensitization of n-type semiconductors (n-SC has been intensively studied, the use of p-type semiconductor (p-SC, e.g., the sensitization of wide bandgap p-SC and hole transport materials with p-SC have also been attracting great attention. Recently, it has been proved that the p-type inorganic semiconductor as a charge selective material or a charge transport material in organometallic lead halide perovskite solar cells (PSCs shows a significant impact on solar cell performance. Therefore the study of p-type semiconductors is important to rationally design efficient DSCs and PSCs. In this review, recent published works on p-type DSCs and PSCs incorporated with an inorganic p-type semiconductor and our perspectives on this topic are discussed.

  3. Precipitation of Cu and Ni in n- and p-type Czochralski-grown silicon characterized by photoluminescence imaging

    Science.gov (United States)

    Sun, Chang; Nguyen, Hieu T.; Rougieux, Fiacre E.; Macdonald, Daniel

    2017-02-01

    Photoluminescence (PL) images and micro-PL maps were taken on Cu- or Ni-doped monocrystalline silicon wafers, to investigate the distribution of the metal precipitates. Several n-type and p-type wafers were used in which Cu or Ni were introduced in the starting melt of the ingots and precipitated during the ingot cooling (as opposed to surface contamination). The micro-PL mapping allowed investigation of the metal precipitates with a higher spatial resolution. Markedly different precipitation patterns were observed in n- and p-type samples: in both Cu- and Ni-doped n-type samples, circular central regions and edge regions were observed. In these regions, particles were distributed randomly and homogeneously. In the p-type Cu-doped and Ni-doped samples, by contrast, the precipitates occurred in lines along orientations. The difference in the precipitation behaviour in n- and p-type samples is conjectured to be caused by different concentrations of self-interstitials and vacancies remaining in the crystal during the ingot cooling: there are more vacancies in the n-type ingots but more interstitials in the p-type ingots. The dopant effects on the intrinsic point defect concentrations in silicon crystals and possible precipitation mechanisms are discussed based on the findings in this work and the literature.

  4. Comparison of ferromagnetism in n- and p-type magnetic semiconductor thin films of ZnCoO

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.H., E-mail: yuhua@phys.ncku.edu.t [Department of Physics, National Cheng Kung University, No. 1, Ta-Shuei Road, Tainan 70101, Taiwan (China); Lee, J.C.; Min, J.F. [Department of Physics, National Cheng Kung University, No. 1, Ta-Shuei Road, Tainan 70101, Taiwan (China); Su, C.W. [Department of Applied Physics, National Chiayi University, Chiayi 60004, Taiwan (China)

    2011-07-15

    Both n- and p-type diluted magnetic semiconductor ZnCoO are made by magnetron co-sputtering with, respectively, dopants of Al and dual dopants of Al and N. The two sputtering targets are compound ZnCoO with 5% weight of Co and pure metal Al. Sputtering gases for n- and p-type films are pure Ar and N{sub 2}, respectively. These films are magnetic at room temperature and possess free electron- and hole-concentration of 5.34x10{sup 20} and 5.27x10{sup 13} cm{sup -3}. Only the n-type film exhibits anomalous Hall-effect signals. Magnetic properties of these two types of films are compared and discussed based on measurements of microstructure and magneto-transport properties. - Research highlights: n-type ZnCoO:Al and p-type ZnCoO:(Al, N) films are made and are both ferromagnetic at room temperature. Signal of anomalous Hall-effect (AHE) is clearly observed only for n-type film but not for p-type film. Photoluminescence (PL) spectrum shows a peak attributed to shallow acceptor band of N. Ferromagnetic exchange coupling between magnetic ions in n-type film is through spin polarized free electrons. Ferromagnetism in p-type film is not attributed to the free hole-carriers mediation but to the overlap of BMP.

  5. Low temperature p-type doping of (Al)GaN layers using ammonia molecular beam epitaxy for InGaN laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Malinverni, M., E-mail: marco.malinverni@epfl.ch; Lamy, J.-M.; Martin, D.; Grandjean, N. [ICMP, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Feltin, E.; Dorsaz, J. [NOVAGAN AG, CH-1015 Lausanne (Switzerland); Castiglia, A.; Rossetti, M.; Duelk, M.; Vélez, C. [EXALOS AG, CH-8952 Schlieren (Switzerland)

    2014-12-15

    We demonstrate state-of-the-art p-type (Al)GaN layers deposited at low temperature (740 °C) by ammonia molecular beam epitaxy (NH{sub 3}-MBE) to be used as top cladding of laser diodes (LDs) with the aim of further reducing the thermal budget on the InGaN quantum well active region. Typical p-type GaN resistivities and contact resistances are 0.4 Ω cm and 5 × 10{sup −4} Ω cm{sup 2}, respectively. As a test bed, we fabricated a hybrid laser structure emitting at 400 nm combining n-type AlGaN cladding and InGaN active region grown by metal-organic vapor phase epitaxy, with the p-doped waveguide and cladding layers grown by NH{sub 3}-MBE. Single-mode ridge-waveguide LD exhibits a threshold voltage as low as 4.3 V for an 800 × 2 μm{sup 2} ridge dimension and a threshold current density of ∼5 kA cm{sup −2} in continuous wave operation. The series resistance of the device is 6 Ω and the resistivity is 1.5 Ω cm, confirming thereby the excellent electrical properties of p-type Al{sub 0.06}Ga{sub 0.94}N:Mg despite the low growth temperature.

  6. Comparison of p-type commercial electron diodes for in vivo dosimetry.

    Science.gov (United States)

    Marre, D; Marinello, G

    2004-01-01

    This paper compares the characteristics of three types of commercial p-type electron diodes specially designed for in vivo dosimetry (Scanditronix EDD2, Sun Nuclear QED 111200-0 and PTW T60010E diodes coupled with a Therados DPD510 dosimeter) in electron fields with energies from 4.5 to 21 MeV, and in conditions similar to those encountered in radiotherapy. In addition to the diodes, a NACP plane parallel ionization chamber and film dosimeters have been used in the experiments. The influence of beam direction on the diode responses (directional effect) was investigated. It was found to be the greatest for the lowest electron beam energy. At 12 MeV and an incidence of +/- 30 degrees, the variation was found to be less than 1% for the Scanditronix and Sun Nuclear diodes and less than 3% for the PTW one. The three diodes exhibited a variation in sensitivity with dose-per-pulse of less than 1% over the range 0.18-0.43 mGy/pulse. The temperature dependence was also studied. The response was linear for the three diodes between 22.2 and 40 degrees C and the sensitivity variations with temperature were (0.25+/-0.01)%/degree C, (0.28+/-0.01)%/degree C, and (0.02 +/-0.01)%/degree C for Scanditronix, Sun Nuclear, and PTW diodes, respectively. Finally the perturbation to the irradiation field induced by the presence of diodes placed at the surface of a homogeneous phantom was investigated and found to be significant, both at the surface and at the depth of maximum dose (several tens of percent) for all three diode types. There is an increase of dose right underneath the diode (close to the surface) and a dose shadow at the depth of maximum. The study shows that electron diodes can be used for in vivo dosimetry provided their characteristics are carefully established before use and taken into consideration at the time of interpretation of the results.

  7. Crystal structure and high temperature transport properties of Yb-filled p-type skutterudites YbxCo2.5Fe1.5Sb12

    KAUST Repository

    Dong, Yongkwan

    2014-01-01

    Partially Yb-filled Fe substituted polycrystalline p-type skutterudites with nominal compositions YbxCo2.5Fe1.5Sb 12, with varying filler concentrations x, were synthesized by reacting the constituent elements and subsequent solid state annealing, followed by densification by hot-pressing. The compositions and filling fractions were confirmed with a combination of Rietveld refinement and elemental analysis. Their thermoelectric properties were evaluated from 300 to 800 K. The Seebeck coefficients for the specimens increase with increasing temperature and plateau at around 750 K. The thermal conductivity decreases with increasing Yb filling fraction, and bipolar conduction becomes evident and increases at elevated temperatures. A maximum ZT value of 0.8 was obtained at 750 K for Yb 0.47Co2.6Fe1.4Sb12. The thermoelectric properties and potential for further optimization are discussed in light of our results. © 2013 Elsevier Inc.

  8. Boric acid solution concentration influencing p-type emitter formation in n-type crystalline Si solar cells

    Science.gov (United States)

    Singha, Bandana; Singh Solanki, Chetan

    2016-09-01

    Boric acid (BA) is a spin on dopant (BSoD) source which is used to form p+ emitters in n-type c-Si solar cells. High purity boric acid powder (99.99% pure) when mixed with deionized (DI) water can result in high quality p-type emitter with less amount of surface defects. In this work, we have used different concentrations of boric acid solution concentrations to fabricate p-type emitters with sheet resistance values < 90 Ω/□. The corresponding junction depths for the same are less than 500 nm as measured by SIMS analysis. Boron rich layer (BRL), which is considered as detrimental in emitter performance is found to be minimal for BA solution concentration less than 2% and hence useful for p-type emitter formation.

  9. Fabrication of p-type ZnO nanofibers by electrospinning for field-effect and rectifying devices

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuai; Liu, Shu-Liang; Liu, Ling-Zhi; Liu, Yi-Chen [College of Physics, Qingdao University, Qingdao 266071 (China); Long, Yun-Ze, E-mail: yunze.long@163.com [College of Physics, Qingdao University, Qingdao 266071 (China); Key Laboratory of Photonics Materials and Technology in Universities of Shandong (Qingdao University), Qingdao 266071 (China); State Key Laboratory Cultivation Base of New Fiber Materials and Modern Textile, Qingdao University, Qingdao 266071 (China); Collaborative Innovation Center for Marine Biomass Fibers, Materials and Textiles of Shandong Province, Qingdao 266071 (China); Zhang, Hong-Di; Zhang, Jun-Cheng; Han, Wen-Peng [College of Physics, Qingdao University, Qingdao 266071 (China); Key Laboratory of Photonics Materials and Technology in Universities of Shandong (Qingdao University), Qingdao 266071 (China)

    2014-01-27

    Ce-doped p-type ZnO nanofibers were synthesized by electrospinning and followed calcinations. The surface morphology, elementary composition, and crystal structure of the nanofibers were investigated. The field effect curve confirms that the resultant Ce-doped ZnO nanofibers are p-type semiconductor. A p-n heterojunction device consisting of Ce-doped p-type ZnO nanofibers and n-type indium tin oxide (ITO) thin film was fabricated on a piece of quartz substrate. The current-voltage (I-V) characteristic of the p-n heterojunction device shows typical rectifying diode behavior. The turn-on voltage appears at about 7 V under the forward bias and the reverse current is impassable.

  10. In silico identification and characterization of the ion transport specificity for P-type ATPases in the Mycobacterium tuberculosis complex

    Directory of Open Access Journals (Sweden)

    Novoa-Aponte Lorena

    2012-10-01

    Full Text Available Abstract Background P-type ATPases hydrolyze ATP and release energy that is used in the transport of ions against electrochemical gradients across plasma membranes, making these proteins essential for cell viability. Currently, the distribution and function of these ion transporters in mycobacteria are poorly understood. Results In this study, probabilistic profiles were constructed based on hidden Markov models to identify and classify P-type ATPases in the Mycobacterium tuberculosis complex (MTBC according to the type of ion transported across the plasma membrane. Topology, hydrophobicity profiles and conserved motifs were analyzed to correlate amino acid sequences of P-type ATPases and ion transport specificity. Twelve candidate P-type ATPases annotated in the M. tuberculosis H37Rv proteome were identified in all members of the MTBC, and probabilistic profiles classified them into one of the following three groups: heavy metal cation transporters, alkaline and alkaline earth metal cation transporters, and the beta subunit of a prokaryotic potassium pump. Interestingly, counterparts of the non-catalytic beta subunits of Hydrogen/Potassium and Sodium/Potassium P-type ATPases were not found. Conclusions The high content of heavy metal transporters found in the MTBC suggests that they could play an important role in the ability of M. tuberculosis to survive inside macrophages, where tubercle bacilli face high levels of toxic metals. Finally, the results obtained in this work provide a starting point for experimental studies that may elucidate the ion specificity of the MTBC P-type ATPases and their role in mycobacterial infections.

  11. Simulation of Enhancement Mode GaN HEMTs with Threshold > 5 V using P-type Buffer

    CERN Document Server

    Bajaj, Sanyam; Krishnamoorthy, Sriram; Hung, Ting-Hsiang; Rajan, Siddharth

    2015-01-01

    A high threshold voltage enhancement-mode GaN HEMT with p-type doped buffer is discussed and simulated. Analytical expressions are derived to explain the role of buffer capacitance in designing and enhancing threshold voltage. Simulations of the proposed device with p-type buffer show threshold voltages above 5 V, and a positive shift in threshold voltage as the oxide capacitance is reduced, thus enabling threshold voltage tunability over an unprecedented range for GaN-based HEMTs. The electric field profiles, breakdown performance, on-resistance and delay tradeoffs in the proposed pGaN back HEMT device are also discussed.

  12. Proton Pumping and Slippage Dynamics of a Eukaryotic P-Type ATPase Studied at the Single-Molecule Level

    DEFF Research Database (Denmark)

    Veshaguri, Salome

    In all eukaryotes the plasma membrane potential and secondary transport systems are energized by P-type ATPases whose regulation however remains poorly understood. Here we monitored at the single-molecule level the activity of the prototypic proton pumping P-type ATPase Arabidopsis thaliana isoform......-intuitively increased the time spent pumping. Allosteric regulation by pH gradients affected the time spent pumping and the leakage probability but surprisingly not the intrinsic pumping rate. Interestingly, ATP dilution decreased the ATP hydrolysis rates in bulk while single molecule data revealed that intrinsic...

  13. Fabrication of p-type SnO{sub 2} films via pulsed laser deposition method by using Sb as dopant

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shihui [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China); Zhang, Weifeng [Key Laboratory of Photovoltaic Materials of Henan Province and School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Li, Linngxia, E-mail: lingxiali@126.com [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China); Xu, Dan; Dong, Helei; Jin, Yuxin [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China)

    2013-12-01

    p-Type transparent conducting antimony-doped tin oxide (ATO) thin films were successfully fabricated on quartz glass substrates by pulsed laser deposition using a 20 at.% Sb doped SnO{sub 2} ceramic target. The growth temperature was varied from 500 to 800 °C, after deposition, the thin films were rapidly annealed at 500 °C in air for 2 h. Several analytical tools such as X-ray diffraction (XRD), Hall measurements, four-point probe, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible–near infrared (UV–Vis–NIR) spectrophotometer were used to explore the causes of the changes in optoelectronic properties and surface micrographs. The Sb-doped SnO{sub 2} film prepared at 700 °C possessed the lowest resistivity of 0.87 Ω cm with a Hall mobility of 0.65 cm{sup 2} v{sup −1} s{sup −1} and hole concentration of 1.01 × 10{sup 19} cm{sup −3}, while the average transmittance is about 85% in the visible light region (400–800 nm). Furthermore, SnO{sub 2}-based p-n homojunction was fabricated by deposition of a Sb-doped p-type SnO{sub 2} layer on a Sb-doped n-type SnO{sub 2} layer.

  14. Interface modification effect between p-type a-SiC:H and ZnO:Al in p-i-n amorphous silicon solar cells.

    Science.gov (United States)

    Baek, Seungsin; Lee, Jeong Chul; Lee, Youn-Jung; Iftiquar, Sk Md; Kim, Youngkuk; Park, Jinjoo; Yi, Junsin

    2012-01-18

    Aluminum-doped zinc oxide (ZnO:Al) [AZO] is a good candidate to be used as a transparent conducting oxide [TCO]. For solar cells having a hydrogenated amorphous silicon carbide [a-SiC:H] or hydrogenated amorphous silicon [a-Si:H] window layer, the use of the AZO as TCO results in a deterioration of fill factor [FF], so fluorine-doped tin oxide (Sn02:F) [FTO] is usually preferred as a TCO. In this study, interface engineering is carried out at the AZO and p-type a-SiC:H interface to obtain a better solar cell performance without loss in the FF. The abrupt potential barrier at the interface of AZO and p-type a-SiC:H is made gradual by inserting a buffer layer. A few-nanometer-thick nanocrystalline silicon buffer layer between the AZO and a-SiC:H enhances the FF from 67% to 73% and the efficiency from 7.30% to 8.18%. Further improvements in the solar cell performance are expected through optimization of cell structures and doping levels.

  15. A Novel Sr2CuInO3S p-type semiconductor photocatalyst for hydrogen production under visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    Yushuai Jia; Jingxiu Yang; Dan Zhao; Hongxian Han; Can Li

    2014-01-01

    A novel Sr2CuInO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations (DFT) and electrochem-ical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocat-alytic hydrogen production experiments under a visible light irradiation (λ>420 nm) were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3S and Rh was found to be the best one among the tested ones.

  16. Mg dopant distribution in an AlGaN/GaN p-type superlattice assessed using atom probe tomography, TEM and SIMS

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, S E; Kappers, M J; Barnard, J S; Humphreys, C J; Oliver, R A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke St., Cambridge, CB2 3QZ (United Kingdom); Clifton, P H; Ulfig, R M, E-mail: sb534@cam.ac.u [Imago Scientific Instruments Corporation, 5500 Nobel Drive, Madison, WI, 53711 (United States)

    2010-02-01

    P-type conducting layers are critical in GaN-based devices such as LEDs and laser diodes. Such layers are often produced by doping GaN with Mg, but the hole concentration can be enhanced using AlGaN/GaN p-type superlattices by exploiting the built-in polarisation fields. A Mg-doped AlGaN/GaN superlattice was studied using SIMS. Although the AlGaN and GaN were nominally doped to the same level, the SIMS data suggested a difference in doping density between the two materials. Atom probe tomography was then used to investigate the Mg distribution. The superlattice repeats were clearly visible, as expected and, in addition, significant Mg clustering was observed in both the GaN and AlGaN layers. There were many more Mg clusters in the AlGaN layers than the GaN layers, accounting for the difference in doping density suggested by SIMS. To evaluate the structural accuracy of the atom probe reconstruction, layer thicknesses from the atom probe were compared with STEM images. Finally, future work is proposed to investigate the Mg clusters in the TEM.

  17. Electrical band-gap narrowing in n- and p-type heavily doped silicon at 300 K

    Science.gov (United States)

    Van Cong, H.; Brunet, S.

    1986-09-01

    Based on previous results band-gap narrowing in heavily doped silicon at 300 K is investigated and expressed in terms of impurity size-and-doping effects. The results obtained for n- and p-type heavily doped silicon are compared with other theories and experiments.

  18. Sodium and potassium doped P-type ZnO films by sol-gel spin-coating technique

    Science.gov (United States)

    Au, Benedict Wen-Cheun; Chan, Kah-Yoong

    2017-07-01

    Zinc oxide (ZnO) is a promising material in a variety of applications including sensors, transistors and solar cells. Many researchers studied N-type ZnO films and reported enhanced properties. On the other hand, P-type ZnO films were rarely attempted due to the self-compensation effect. Success in achieving P-type ZnO films is important as it will pave the way for more advanced complementary devices. In this work, P-type sodium and potassium doped ZnO films were fabricated on glass substrates with doping concentration between 0 and 25 at.%. The influences of doping concentration on surface morphology, structural, optical and electrical properties were investigated using atomic force microscopy, X-ray diffraction spectroscopy, energy-dispersive X-ray spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometer, photoluminescence spectroscopy and Hall-effect electrical transport measurement system. The distinctive behavior of P-type ZnO films with different doping concentrations will be discussed.

  19. Study of p-type ZnO and MgZnO Thin Films for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jianlin [Univ. of California, Riverside, CA (United States)

    2015-07-31

    This project on study of p-type ZnO and MgZnO thin films for solid state lighting was carried out by research group of Prof. Jianlin Liu of UCR during the four-year period between August 2011 and July 2015. Tremendous progress has been made on the proposed research. This final report summarizes the important findings.

  20. Ab initio studies on n-type and p-type Li4Ti5O12

    Institute of Scientific and Technical Information of China (English)

    Zhong Zhi-Yong; Nie Zheng-Xin; Du Yan-Lan; Ouyang Chu-Ying; Shi Si-Qi; Lei Min-Sheng

    2009-01-01

    This paper studies the structure and electronic properties of Li4Ti5O12, as anode material for lithium ion batteries,from first principles calculations. The results suggest that there are two kinds of unit cell of Li4Ti5O12: n-type and p-type. The two unit cells have different structures and electronic properties: the n-type with two 16d site Li ions is metallic by electron, while the p-type with three 16d Li ions is metallic by hole. However, the Li4Ti5O12 is an insulator.It is very interesting that one n-type cell and two p-type cells constitute one Li4Ti5O12 supercell which is insulating.The results show that the intercalation potential obtained with a p-type unit cell with one additional electron is quite close to the experimental value of 1.5 V.

  1. 两开关伪连续导电模式Buck.Boost功率因数校正变换器%Two-switch Pseudo Continuous Conduction Mode Buck-Boost Power Factor Correction Converter

    Institute of Scientific and Technical Information of China (English)

    张斐; 许建平; 杨平; 陈章勇

    2012-01-01

    A novel two-switch Buck-Boost power factor correction (PFC) converter operating in pseudo continuous conduction mode (PCCM) and its corresponding control strategy were proposed in this paper. The two-switch PCCM Buck-Boost PFC topology provides an additional degree of control freedom to realize PFC control, which can offer significant performance improvements over single-switch Buck-Boost PFC converters or two-switch Buck-Boost PFC converters in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The additional degree of control freedom introduced by inductor current freewheeling stage helps to achieve unity power factor control. Besides, inductor current ripple of the two-switch PCCM Buck-Boost PFC converter, which is lower than that of the two-switch DCM Buck-Boost PFC converter, can be obtained. Analysis, simulation and experiment results of the two-switch PCCM Buck-Boost PFC converter were presented. The experiment results show that the dynamic response of the two-switch PCCM Buck-Boost PFC converter is significantly faster than that of the two-switch CCM and DCM Buck-Boost PFC converter.%提出两开关伪连续导电模式(pseudocontinuousconductionmode,PCCM)Buck-Boost功率因数校jE(powerfactorcorrection,PFC)变换器及其控制策略。利用两开关PCCMBuck.BoostPFC变换器电感惯性模态所提供的一个额外控制自由度,可实现单位功率因数控制,并明显改善传统单开关Buck-BoostPFC变换器、两开关连续导电模式(continuousconductionmode,CCM)Buck.BoostPFC变换器和两开关不连续导电模式(discontinuousconductionmode,DCM)Buck-BoostPFC变换器的性能。与两开关DCMBuck.BoostPFC变换器相比,两开关PCCMBuck.BoostPFC变换器减小了电感电流纹波。仿真与实验结果表明,两开关PCCMBuck-BoostPFC变换器的负载动态响应速度明显快于传统的两开关CCM和DCMBuck-BoostPFC变换器。

  2. n- and p-type transport in (110) GaAs substrates, single- and double-cleave structures

    Energy Technology Data Exchange (ETDEWEB)

    Roth, S.F.

    2007-06-06

    In this work low-dimensional systems based on GaAs/AlGaAs are investigated with either holes (p-type) in two-dimensional (2D) systems or electrons (n-type) in one-dimensional (1D) systems as charge carriers. Two-dimensional hole systems (2DHS) are grown with molecular beam epitaxy both on (110) wafers and (1 anti 10) facets with the cleaved-edge overgrowth (CEO) method. We use Si as an acceptor by modulating the growth conditions to fabricate the 2DHS in single-interface heterojunction quantum wells. The mobility of the structures reaches up to 7.0 x 10{sup 5} cm{sup 2}/Vs along the [1 anti 10]-direction and 4.1 x 10{sup 5} cm{sup 2}/Vs along the [001]-direction at a hole density of 1.2 x 10{sup 11} cm{sup -2}. Effective values for anisotropic effective hole masses and scattering times are obtained. Inversion asymmetry induced spin splitting results in different spin densities, which yield beatings of the Shubnikov-de Haas oscillations at low temperatures. In a perpendicular magnetic field the 2DHS is quantized into Landau levels, which depend nonlinearly on B due to a strong mixing of light- and heavy-holes. When the Landau levels anticross on the (110) facet, additional peaks appear within minima of the quantum Hall effect. Thermal activation measurements demonstrate a B-dependent energy gap consistent with such an anticrossing. In the second part of the thesis an electron quantum wire is fabricated with twofold cleaved-edge overgrowth. A variation of the conduction band energy in the substrate layers can directly transfer a potential modulation to the adjacent quantum wire. The concept of a transfer potential applied to a narrow two-dimensional system is demonstrated as a first step. Finally, in narrow quantum well samples a simple vertical quantum wire is successfully demonstrated and contacted at each end with n{sup +}-GaAs layers via two-dimensional (2D) leads. We characterize the 2D lead density and mobility for both cleave facets with four

  3. P-type nitrogen-doped ZnO nanostructures with controlled shape and doping level by facile microwave synthesis.

    Science.gov (United States)

    Herring, Natalie P; Panchakarla, Leela S; El-Shall, M Samy

    2014-03-04

    We report herein the development of a facile microwave irradiation (MWI) method for the synthesis of high-quality N-doped ZnO nanostructures with controlled morphology and doping level. We present two different approaches for the MWI-assisted synthesis of N-doped ZnO nanostructures. In the first approach, N-doping of Zn-poor ZnO prepared using zinc peroxide (ZnO2) as a precursor is carried out under MWI in the presence of urea as a nitrogen source and oleylamine (OAm) as a capping agent for the shape control of the resulting N-doped ZnO nanostructures. Our approach utilizes the MWI process for the decomposition of ZnO2, where the rapid transfer of energy directly to ZnO2 can cause an instantaneous internal temperature rise and, thus, the activation energy for the ZnO2 decomposition is essentially decreased as compared to the decomposition under conductive heating. In the second synthesis method, a one-step synthesis of N-doped ZnO nanostructures is achieved by the rapid decomposition of zinc acetate in a mixture of urea and OAm under MWI. We demonstrate, for the first time, that MWI decomposition of zinc acetate in a mixture of OAm and urea results in the formation of N-doped nanostructures with controlled shape and N-doping level. We report a direct correlation between the intensity of the Raman scattering bands in N-doped ZnO and the concentration of urea used in the synthesis. Electrochemical measurements demonstrate the successful synthesis of stable p-type N-doped ZnO nanostructures using the one-step MWI synthesis and, therefore, allow us to investigate, for the first time, the relationship between the doping level and morphology of the ZnO nanostructures. The results provide strong evidence for the control of the electrical behavior and the nanostructured shapes of ZnO nanoparticles using the facile MWI synthesis method developed in this work.

  4. Electronic Properties of Red P-Type Tl2S5 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    G. A. Gamal; M. Abou Zied; A. A. Ebnalwaled

    2005-01-01

    @@ Single crystals of red Tl2S5 were prepared by a special modified vertical Bridgman and Stockbarger technique.This growth was performed in our laboratory. The influences of temperature on the electrical conductivity, Hall mobility, carrier concentration, and thermoelectric power (TEP) were carried out in the temperature range 277-413 K. Throughout these measurements, various physical parameters such as effective mass of charge carriers,carrier mobility, diffusion coefficient, and the relaxation time for both majority and minority carriers were found.

  5. Conduct disorder

    Science.gov (United States)

    ... Conduct disorder is often linked to attention-deficit disorder . Conduct disorder also can be an early sign of ... child or teen has a history of conduct disorder behaviors. A physical examination and blood tests can help ...

  6. Effect of oxygen and ozone on p-type doping of ultra-thin WSe2 and MoSe2 field effect transistors.

    Science.gov (United States)

    Wang, Shunfeng; Zhao, Weijie; Giustiniano, Francesco; Eda, Goki

    2016-02-14

    We report on the p-type doping effect of oxygen and ozone molecules on mono- and few-layer WSe2 and MoSe2 field effect transistors. We show that adsorption of oxygen and ozone under ambient conditions results in subtantial doping and corresponding enhancement in the hole conductivity of the devices. Ozone-induced doping is found to be rapid and efficient, saturating within minutes of exposure whereas oxygen-induced doping occurs over a period of days to reach the equivalent level of doping. Our observations reveal that the water adlayer on the material surface plays a crucial role in solubilizing oxygen and ozone and in forming a redox couple with a large chemical potential.

  7. Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells

    Science.gov (United States)

    Jenatsch, Sandra; Geiger, Thomas; Heier, Jakob; Kirsch, Christoph; Nüesch, Frank; Paracchino, Adriana; Rentsch, Daniel; Ruhstaller, Beat; C Véron, Anna; Hany, Roland

    2015-01-01

    Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability. PMID:27877804

  8. Hydrogen plasma treatment of very thin p-type nanocrystalline Si films grown by RF-PECVD in the presence of B(CH33

    Directory of Open Access Journals (Sweden)

    Sergej Alexandrovich Filonovich, Hugo Águas, Tito Busani, António Vicente, Andreia Araújo, Diana Gaspar, Marcia Vilarigues, Joaquim Leitão, Elvira Fortunato and Rodrigo Martins

    2012-01-01

    Full Text Available We have characterized the structure and electrical properties of p-type nanocrystalline silicon films prepared by radio-frequency plasma-enhanced chemical vapor deposition and explored optimization methods of such layers for potential applications in thin-film solar cells. Particular attention was paid to the characterization of very thin (~20 nm films. The cross-sectional morphology of the layers was studied by fitting the ellipsometry spectra using a multilayer model. The results suggest that the crystallization process in a high-pressure growth regime is mostly realized through a subsurface mechanism in the absence of the incubation layer at the substrate-film interface. Hydrogen plasma treatment of a 22-nm-thick film improved its electrical properties (conductivity increased more than ten times owing to hydrogen insertion and Si structure rearrangements throughout the entire thickness of the film.

  9. Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells.

    Science.gov (United States)

    Jenatsch, Sandra; Geiger, Thomas; Heier, Jakob; Kirsch, Christoph; Nüesch, Frank; Paracchino, Adriana; Rentsch, Daniel; Ruhstaller, Beat; C Véron, Anna; Hany, Roland

    2015-06-01

    Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability.

  10. Fe-Doping Effect on Thermoelectric Properties of p-Type Bi0.48Sb1.52Te3

    Directory of Open Access Journals (Sweden)

    Hyeona Mun

    2015-03-01

    Full Text Available The substitutional doping approach has been shown to be an effective strategy to improve ZT of Bi2Te3-based thermoelectric raw materials. We herein report the Fe-doping effects on electronic and thermal transport properties of polycrystalline bulks of p-type Bi0.48Sb1.52Te3. After a small amount of Fe-doping on Bi/Sb-sites, the power factor could be enhanced due to the optimization of carrier concentration. Additionally, lattice thermal conductivity was reduced by the intensified point-defect phonon scattering originating from the mass difference between the host atoms (Bi/Sb and dopants (Fe. An enhanced ZT of 1.09 at 300 K was obtained in 1.0 at% Fe-doped Bi0.48Sb1.52Te3 by these synergetic effects.

  11. Synthesis and Electronic Transport of Hydrothermally Synthesized p-Type Na-Doped SnSe

    Science.gov (United States)

    Yang, Zong-Ren; Chen, Wei-Hao; Liu, Chia-Jyi

    2016-11-01

    A series of polycrystalline Sn1-x Na x Se with x = 0.00, 0.02, 0.04 and 0.10 were fabricated using hydrothermal synthesis followed by evacuated-and-encapsulated sintering. The as-fabricated materials were characterized using powder x-ray diffraction and electronic transport. The resulting materials were single phase. Partial replacement of Na for Sn leads to a simultaneous increase of electrical conductivity and thermopower. The x = 0.04 sample has the largest power factor among the series of the samples. Upon partial replacement of Na for Sn, the power factor is significantly enhanced as compared to the undoped SnSe. The maximum ZT value of ˜0.4 was achieved for Sn0.96Na0.04Se at 550 K.

  12. Nanostructured p-type semiconducting transparent oxides: promising materials for nano-active devices and the emerging field of "transparent nanoelectronics".

    Science.gov (United States)

    Banerjee, Arghya; Chattopadhyay, Kalyan K

    2008-01-01

    Transparent conducting oxides (TCO) with p-type semiconductivity have recently gained renewed interest for the fabrication of all-oxide transparent junctions, having potential applications in the emerging field of 'Transparent' or 'Invisible Electronics'. This kind of transparent junctions can be used as a "functional" window, which will transmit visible portion of solar radiation, but generates electricity by the absorption of the UV part. Therefore, these devices can be used as UV shield as well as UV cells. In this report, a brief review on the research activities on various p-TCO materials is furnished along-with the fabrication of different transparent p-n homojunction, heterojunction and field-effect transistors. Also the reason behind the difficulties in obtaining p-TCO materials and possible solutions are discussed in details. Considerable attention is given in describing the various patent generations on the field of p-TCO materials as well as transparent p-n junction diodes and light emitting devices. Also, most importantly, a detailed review and patenting activities on the nanocrystalline p-TCO materials and transparent nano-active device fabrication are furnished with considerable attention. And finally, a systematic description on the fabrication and characterization of nanocrystalline, p-type transparent conducting CuAlO(2) thin film, deposited by cost-effective low-temperature DC sputtering technique, by our group, is furnished in details. These p-TCO micro/nano-materials have wide range of applications in the field of optoelectronics, nanoelectronics, space sciences, field-emission displays, thermoelectric converters and sensing devices.

  13. Efficient photoelectrochemical water splitting over anodized p-type NiO porous films.

    Science.gov (United States)

    Hu, Chenyan; Chu, Kenneth; Zhao, Yihua; Teoh, Wey Yang

    2014-11-12

    NiO photocathodes were fabricated by alkaline etching-anodizing nickel foil in an organic-based electrolyte. The resulting films have a highly macroporous surface structure due to rapid dissolution of the oxide layer as it is formed during the anodization process. We are able to control the films' surface structures by varying the anodization duration and voltage. With an onset potential of +0.53 V versus the reversible hydrogen electrode (RHE), the photocurrent efficiency of the NiO electrodes showed dependencies on their surface roughness factor, which determines the extent of semiconductor-electrolyte interface and the associated quality of the NiO surface sites. A maximum incident photon-to-current conversion efficiency (IPCE(max)) of 22% was obtained from NiO film with a roughness factor of 8.4. Adding an Al2O3 blocking layer minimizes surface charge recombination on the NiO and hence increased the IPCE(max) to 28%. The NiO/Al2O3 films were extremely stable during photoelectrochemical water splitting tests lasting up to 20 h, continuously producing hydrogen and oxygen in the stoichiometric 2:1 ratio. The NiO/Al2O3 and NiO films fabricated using the alkaline anodization process produced 12 and 6 times as much hydrogen, respectively, as those fabricated using commercial NiO nanoparticles.

  14. Electrical conductivity, ionic conductivity, optical absorption, and gas separation properties of ionically conductive polymer membranes embedded with Si microwire arrays

    OpenAIRE

    Spurgeon, Joshua M.; Walter, Michael G.; Zhou, Junfeng; Kohl, Paul A.; Lewis, Nathan S.

    2011-01-01

    The optical absorption, ionic conductivity, electronic conductivity, and gas separation properties have been evaluated for flexible composite films of ionically conductive polymers that contain partially embedded arrays of ordered, crystalline, p-type Si microwires. The cation exchange ionomer Nafion, and a recently developed anion exchange ionomer, poly(arylene ether sulfone) that contains quaternary ammonium groups (QAPSF), produced composite microwire array/ionomer membrane films that were...

  15. P-type Cu2O/SnO bilayer thin film transistors processed at low temperatures

    KAUST Repository

    Al-Jawhari, Hala A.

    2013-10-09

    P-type Cu2O/SnO bilayer thin film transistors (TFTs) with tunable performance were fabricated using room temperature sputtered copper and tin oxides. Using Cu2O film as capping layer on top of a SnO film to control its stoichiometry, we have optimized the performance of the resulting bilayer transistor. A transistor with 10 nm/15 nm Cu2O to SnO thickness ratio (25 nm total thickness) showed the best performance using a maximum process temperature of 170 C. The bilayer transistor exhibited p-type behavior with field-effect mobility, on-to-off current ratio, and threshold voltage of 0.66 cm2 V-1 s-1, 1.5×10 2, and -5.2 V, respectively. The advantages of the bilayer structure relative to single layer transistor are discussed. © 2013 American Chemical Society.

  16. Growth of nitrogen-doped p-type ZnO thin films prepared by atomic layer epitaxy

    Institute of Scientific and Technical Information of China (English)

    LEE Chongmu; LIM Jongmin; PARK Suyoung; KIM Hyounwoo

    2006-01-01

    Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2[Diethylzinc,DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and a doping source gas, respectively. The lowest electrical resistivity of the p-type ZnO films grown by ALE and annealed at 1000 ℃ in an oxygen atmosphere for 1 h was 18.3 Ω·m with a hole concentration of 3.71×1017cm-3 . Low temperature-photoluminescence analysis and time-dependent Hall measurement results support that the nitrogen-doped ZnO after annealing is ap-type semiconductor.

  17. Odd-Integer Quantum Hall States and Giant Spin Susceptibility in p -Type Few-Layer WSe2

    Science.gov (United States)

    Xu, Shuigang; Shen, Junying; Long, Gen; Wu, Zefei; Bao, Zhi-qiang; Liu, Cheng-Cheng; Xiao, Xiao; Han, Tianyi; Lin, Jiangxiazi; Wu, Yingying; Lu, Huanhuan; Hou, Jianqiang; An, Liheng; Wang, Yuanwei; Cai, Yuan; Ho, K. M.; He, Yuheng; Lortz, Rolf; Zhang, Fan; Wang, Ning

    2017-02-01

    We fabricate high-mobility p -type few-layer WSe2 field-effect transistors and surprisingly observe a series of quantum Hall (QH) states following an unconventional sequence predominated by odd-integer states under a moderate strength magnetic field. By tilting the magnetic field, we discover Landau level crossing effects at ultralow coincident angles, revealing that the Zeeman energy is about 3 times as large as the cyclotron energy near the valence band top at the Γ valley. This result implies the significant roles played by the exchange interactions in p -type few-layer WSe2 , in which itinerant or QH ferromagnetism likely occurs. Evidently, the Γ valley of few-layer WSe2 offers a unique platform with unusually heavy hole carriers and a substantially enhanced g factor for exploring strongly correlated phenomena.

  18. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Bradley, A. W.; Brudanin, V.; Busch, M.; Buuck, M.; Caldwell, A. S.; Chan, Y. -D.; Christofferson, C. D.; Chu, P. -H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Finnerty, P. S.; Galindo-Uribarri, A.; Gilliss, T.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Jasinski, B. R.; Keeter, K. J.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; MacMullin, J.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Orrell, J. L.; O’Shaughnessy, C.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C. -H.; Yumatov, V.; Zhitnikov, I.

    2016-11-11

    A search for Pauli-exclusion-principle-violating K electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

  19. First results on charge collection efficiency of heavily irradiated microstrip sensors fabricated on oxygenated p-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Casse, G. E-mail: gcasse@hep.ph.liv.ac.uk; Allport, P.P.; Marti i Garcia, S.; Lozano, M.; Turner, P.R

    2004-02-01

    Heavy hadron irradiation leads to type inversion of n-type silicon detectors. After type inversion, the charge collected at low bias voltages by silicon microstrip detectors is higher when read out from the n-side compared to p-side read out. The n-side read out has been successfully used in combination with oxygen-enriched n-type silicon substrate to maximise the radiation hardness of microstrip detectors. Alternatively, the n-side read out can be implemented on p-type substrates reducing the complexity of fabrication. Miniature silicon microstrip detectors made on standard and oxygen-enriched p-type substrate have been produced. The charge collection properties of such detectors with and without oxygenation are here compared for the first time after severe charged hadron irradiation.

  20. Increased Photoconductivity Lifetime in GaAs Nanowires by Controlled n-Type and p-Type Doping.

    Science.gov (United States)

    Boland, Jessica L; Casadei, Alberto; Tütüncüoglu, Gözde; Matteini, Federico; Davies, Christopher L; Jabeen, Fauzia; Joyce, Hannah J; Herz, Laura M; Fontcuberta I Morral, Anna; Johnston, Michael B

    2016-04-26

    Controlled doping of GaAs nanowires is crucial for the development of nanowire-based electronic and optoelectronic devices. Here, we present a noncontact method based on time-resolved terahertz photoconductivity for assessing n- and p-type doping efficiency in nanowires. Using this technique, we measure extrinsic electron and hole concentrations in excess of 10(18) cm(-3) for GaAs nanowires with n-type and p-type doped shells. Furthermore, we show that controlled doping can significantly increase the photoconductivity lifetime of GaAs nanowires by over an order of magnitude: from 0.13 ns in undoped nanowires to 3.8 and 2.5 ns in n-doped and p-doped nanowires, respectively. Thus, controlled doping can be used to reduce the effects of parasitic surface recombination in optoelectronic nanowire devices, which is promising for nanowire devices, such as solar cells and nanowire lasers.

  1. Preparation and Properties of N-Doped p-Type ZnO Films by Solid-Source Chemical Vapour Deposition with the c-Axis Parallel to the Substrate

    Institute of Scientific and Technical Information of China (English)

    吕建国; 叶志镇; 汪雷; 赵炳辉; 黄靖云

    2002-01-01

    We report on N-doped p-type ZnO films with the c-axis parallel to the substrate. ZnO films were prepared onan α-A12O3 (0001) substrate by solid-source chemical vapour deposition (CVD). Zn( CH3COO)2.2H2O was usedas the precursor and CH3COONH4 as the nitrogen source. The growth temperature was varied from 300℃ C to600℃ C. The as-grown ZnO film deposited at 500° C showed p-type conduction with its resistivity of 42 Ωcrm, carrierdensity 3.7 × 1017 cm-3 and Hall mobility 1.26cm2V-1.s-1 at room temperature, which are the best propertiesfor p-type ZnO deposited by CVD. The p-type ZnO film possesses a transmittance of about 85% in the visibleregion and a bandgap of 3.21 eV at room temperature.

  2. Effects of air-annealing on the electrical properties of p-type tin monoxide thin-film transistors

    Science.gov (United States)

    Cho, In-Tak; U, Myeonghun; Song, Sang-Hun; Lee, Jong-Ho; Kwon, Hyuck-In

    2014-04-01

    We have investigated the effects of air-annealing on the electrical performance of the p-type tin oxide thin-film transistors (TFTs). The air-annealing of the tin oxide thin-film was made using a mini furnace at various temperatures. From the x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) data, it is demonstrated that the phase of tin oxide partially transforms from SnO to SnO2 with an air-annealing process, and it accelerates as the annealing temperature increases. The electrical performance of the p-type tin oxide TFT with a channel thickness of 25 nm exhibits much improved electrical performance when air-annealed at 230 °C for 1 h, but a decrease of the on-current is observed with an ambipolar operation in 260 and 290 °C air-annealed devices. Based on the XPS, XRD, and Hall measurement data, the reduced hole concentration inside the channel due to the recombination with electrons from SnO2 is believed to be the reason for the electrical performance improvement in 230 °C air-annealed p-type tin oxide TFTs, and a partial formation of n-type SnO2 channel is considered as the plausible reason for the ambipolar operation in tin oxide TFTs with high annealing temperatures. Our experimental results show that there is an optimum air-annealing temperature which can improve the electrical performance in p-type tin oxide TFTs.

  3. Radioisotope space power generator. Annual report, July 1, 1975--September 30, 1976. [TPM-217 P-type selenides

    Energy Technology Data Exchange (ETDEWEB)

    Elsner, N.B.; Chin, J.; Staley, H.G.; Steeger, E.J.; Gantzel, P.K.

    1977-09-01

    TPM-217 P-type selenide usefulness in thermoelectric converters depends on its dimensional, electrical and thermal stability at high temperature and its compatibility with other converter component materials in a low pressure environment. Experimental efforts have been directed at determining: the vaporization behavior at 900/sup 0/C, the partial pressures of vaporizing species versus temperature, vapor suppression coatings, thermal expansion, dimensional stability, and the high temperature compatibility of TPM-217 with proposed end cap materials.

  4. Optical characteristics of p-type GaAs-based semiconductors towards applications in photoemission infrared detectors

    Science.gov (United States)

    Lao, Y. F.; Perera, A. G. U.; Wang, H. L.; Zhao, J. H.; Jin, Y. J.; Zhang, D. H.

    2016-03-01

    Free-carrier effects in a p-type semiconductor including the intra-valence-band and inter-valence-band optical transitions are primarily responsible for its optical characteristics in infrared. Attention has been paid to the inter-valence-band transitions for the development of internal photoemission (IPE) mid-wave infrared (MWIR) photodetectors. The hole transition from the heavy-hole (HH) band to the spin-orbit split-off (SO) band has demonstrated potential applications for 3-5 μm detection without the need of cooling. However, the forbidden SO-HH transition at the Γ point (corresponding to a transition energy Δ0, which is the split-off gap between the HH and SO bands) creates a sharp drop around 3.6 μm in the spectral response of p-type GaAs/AlGaAs detectors. Here, we report a study on the optical characteristics of p-type GaAs-based semiconductors, including compressively strained InGaAs and GaAsSb, and a dilute magnetic semiconductor, GaMnAs. A model-independent fitting algorithm was used to derive the dielectric function from experimental reflection and transmission spectra. Results show that distinct absorption dip at Δ0 is observable in p-type InGaAs and GaAsSb, while GaMnAs displays enhanced absorption without degradation around Δ0. This implies the promise of using GaMnAs to develop MWIR IPE detectors. Discussions on the optical characteristics correlating with the valence-band structure and free-hole effects are presented.

  5. THERMOELECTRIC PROPERTIES OF HOT-PRESSED p-TYPE Mg2Si0.3Sn0.7 SOLID SOLUTION

    Directory of Open Access Journals (Sweden)

    G. N. Isachenko

    2014-05-01

    Full Text Available It is shown that thermoelectric energy conversion which gives the possibility for utilizing a low potential heat is one of the ways for adoption of energy-saving technologies; and semiconductor materials with p-type and n-type conductivities having high thermoelectric figure of merit are necessary for operation of thermoelectric generators. The paper deals with possibility of usage of the p-Mg2Si0.3Sn0.7 solid solution (with a nanostructured modification as a couple for the well studied thermoelectric material based on n-Mg2Si-Mg2Sn. A technological scheme for fabrication of heavily doped Mg2Si0.3Sn0.7 solid solution of p-type by hot pressing from nanopowder is developed. The given technology has made it possible to reduce duration of a homogeneous material fabrication and has improved its physical and chemical properties. The samples were made by three ways: direct fusion for polycrystals fabrication; hot pressing from microparticles; nanostructuring, i.e. hot pressing from nanoparticles. By X-ray diffraction it is shown that sizes of structural elements in the fabricated samples are about 40 nm. The probe technique is used for measurement of electric conductivity and Seebeck coefficient. The stationary absolute method is used for measurement of thermal conductivity. Thermoelectric figure of merit is defined by measured values of kinetic coefficients in the temperatures range of 77 – 800 K. It was demonstrated, that electric conductivity, Seebeck coefficient and the power factor do not depend practically on a way of solid solution preparation. Thermal conductivity of samples pressed from nanoparticles has appeared to be higher, than of samples, obtained by direct fusion; i.e. in this case nanostructuring has not led to increase of thermoelectric figure of merit. The conclusion is drawn, that polycrystalline semiconductor Mg2Si0.3Sn0.7 can be used as a p-branch for a thermoelectric generator though nanostructuring has not led to the figure of

  6. Improved Thermoelectric Performance of p-type Skutterudite YbxFe4-yPtySb12 (0.8 x 1, y = 1 and 0.5)

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jung Y [GM R& D and Planning, Warren, Michigan; Ye, Zuxin [GM Research and Development Center; Tessema, Misle [GM Research and Development Center; Salvador, James R. [GM R& D and Planning, Warren, Michigan; Waldo, Richard [GM R& D and Planning, Warren, Michigan; Yang, Jiong [Chinese Academy of Sciences; Zhang, Weiqing [Chinese Academy of Sciences; Yang, Jihui [University of Washington; Cai, Wei [ORNL; Wang, Hsin [ORNL

    2013-01-01

    Thermoelectric performance of p-type skutterudites currently lags that of the corresponding n-type materials and improvement of this important class of materials have become the focus of considerable research effort world-wide. Recent calculations find promising band structural features in p-type skutterudite materials of the type AeFe3NiSb12 ( Ae = Ca, Sr, or Ba) which could potentially lead to excellent thermoelectric properties. Recent work on the Yb- filled analog of the these formulations (YbFe3NiSb12) however finds that the onset of intrinsic conduction at lower than expected temperatures deteriorates the performance above 500 K leading to poor performance in the temperature range of interest for automotive waste heat recovery applications. We therefore seek a way to increase the band gap in order to find a way to minimize the deleterious effects of intrinsic conduction. Here we present ab initio band structure calculations and the synthesis and thermoelectric properties of YbxFe4-yPtySb12 (0.8 x 1, y = 1 and 0.5). Ab initio calculations find that the band gap increases for YbFe3PtSb12 as compared to the Ni-containing analog, though no such increase in the band gap energy was found for as compared to YbFe3.5Ni0.5Sb12. The y = 1 samples shows a characteristic transition to intrinsic conduction with a decrease in the Seebeck coefficient at temperatures above 700 K. The increased carrier concentration in y = 0.5 virtually eliminates any evidence of intrinsic conduction and the Seebeck coefficients for these samples increase monotonically up to 750 K, resulting in power factors approaching 27 W/cm K2 at 750 K. These power factors combined with low thermal conductivity result in a ZT = 0.9 at 750 K for Yb0.95Fe3.5Pt0.5Sb12.

  7. Na-Diffusion Enhanced p-type Conductivity in Cu(In,Ga)Se 2 : A New Mechanism for Efficient Doping in Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Zhen-Kun [Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physicsand Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 China; Chen, Shiyou [Key Laboratory of Polar Materials and Devices (MOE), East China Normal University, Shanghai 200241 China; Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan Shanxi 030006 China; Xie, Yun [Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physicsand Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 China; Park, Ji-Sang [National Renewable Energy Laboratory, Golden CO 80401 USA; Xiang, Hongjun [Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physicsand Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 China; Gong, Xin-Gao [Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physicsand Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 China; Wei, Su-Huai [Beijing Computational Science Research Center, Beijing 100094 China

    2016-08-30

    A new mechanism responsible for the hole concentration increase in the CIGS thin films after Na doping is proposed. At high temperature, a high concentration of Na is doped into the grains. After cooling and water rinsing, the solubility of Na becomes lower, so Na diffuses out of the grains with high concentration of Cu vacancies and hole carriers formed.

  8. Fabrication of CdS/CdTe solar cells with transparent p-type conductive BaCuSeF back contact

    Science.gov (United States)

    Yamamoto, Koichi; Sakakima, Hiroshi; Ogawa, Yohei; Hosono, Aikyo; Okamoto, Tamotsu; Wada, Takahiro

    2015-08-01

    BaCuSeF films were applied to CdS/CdTe solar cells as back electrodes. The interfaces between the CdTe and BaCuSeF layers in the CdS/CdTe solar cells with BaCuSeF back contact deposited at substrate temperatures (TS) of 200 and 300 °C were analyzed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). We clearly observed many dislocations in the CdTe layer in the CdS/CdTe solar cell with the BaCuSeF layer deposited at TS = 300 °C. We also observed a reaction layer of Cu2.72Te2 between the BaCuSeF and CdTe layers in both solar cells. We concluded that (1) the substrate temperature for the pulsed laser deposition of the BaCuSeF layer and (2) the interface between the CdTe and BaCuSeF layers are important factors for the performance of the CdTe solar cells. We obtained high conversion efficiency of 8.31% for a solar cell with a BaCuSeF layer deposited at TS = 200 °C on a CdTe surface etched in a NH3 aqueous solution. The highest conversion efficiency of 9.91% was obtained for a solar cell with a CdTe surface etched in a bromide-bromate solution.

  9. Measurement and Theory of the Hall Scattering Factor and the Conductivity Mobility in Ultra Pure p-Type Silicon at Low Temperatures.

    Science.gov (United States)

    1983-04-01

    required by security considerations, contractual obligations, or notice on a specific document. Unclassified SECURITY CLASS’FICATION OF THIS PAGE ("W a Dfat ...diamond structure, fraction- al translations in a unit cell are too small on the macroscopic scale to influence the results of experimental

  10. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering

    Directory of Open Access Journals (Sweden)

    Yun Zheng

    2017-06-01

    Full Text Available P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473–573 K and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te3 commercial zone-melting (ZM ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS, and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te3 compounds prepared by the MS-PAS technique.

  11. Properties and local environment of p-type and photoluminescent rare earths implanted into ZnO single crystals

    CERN Document Server

    Rita, EMC; Wahl, U; Soares, JC

    This thesis presents an experimental study of the local environment of p-type and Rare- Earth dopants implanted in ZnO single-crystals (SCs). Various nuclear and bulk property techniques were combined in the following evaluations: Implantation damage annealing was evaluated in ZnO SCs implanted with Fe, Sr and Ca. P-type dopants Cu and Ag implanted ZnO SCs were studied revealing that the solubility of Cu in substituting Zn is considerably higher than that of Ag. These results are discussed within the scope of the ZnO p-type doping problematic with these elements. Experimental proofs of the As “anti-site” behavior in ZnO were for the first time attained, i.e., the majority of As atoms are substitutional at the Zn site (SZn), possibly surrounded by two Zn vacancies (VZn). This reinforces the theoretical prediction that As acts as an acceptor in ZnO via the AsZn-2VZn complex formation. The co-doping of ZnO SC with In (donor) and As (acceptor) was addressed. The most striking result is the possible In-As “p...

  12. S-Type and P-Type Habitability in Stellar Binary Systems: A Comprehensive Approach. I. Method and Applications

    CERN Document Server

    Cuntz, Manfred

    2013-01-01

    A comprehensive approach is provided to the study of both S-type and P-type habitability in stellar binary systems, which in principle can also be expanded to systems of higher order. P-type orbits occur when the planet orbits both binary components, whereas in case of S-type orbits the planet orbits only one of the binary components with the second component considered a perturbator. The selected approach encapsulates a variety of different aspects, which include: (1) The consideration of a joint constraint including orbital stability and a habitable environment for a putative system planet through the stellar radiative energy fluxes ("radiative habitable zone"; RHZ) needs to be met. (2) The treatment of conservative, general and extended zones of habitability for the various systems as defined for the Solar System and beyond. (3) The providing of a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are presented for which kind of system S-type ...

  13. S-Type and P-Type Habitability in Stellar Binary Systems: A Comprehensive Approach. II. Elliptical Orbits

    CERN Document Server

    Cuntz, Manfred

    2014-01-01

    In the first paper of this series, a comprehensive approach has been provided for the study of S-type and P-type habitable regions in stellar binary systems, which was, however, restricted to circular orbits of the stellar components. Fortunately, a modest modification of the method also allows for the consideration of elliptical orbits, which of course entails a much broader range of applicability. This augmented method is presented here, and numerous applications are conveyed. In alignment with Paper I, the selected approach considers a variety of aspects, which comprise the consideration of a joint constraint including orbital stability and a habitable region for a putative system planet through the stellar radiative energy fluxes (radiative habitable zone; RHZ). The devised method is based on a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are deduced for which kinds of systems S-type and P-type habitable zones are realized. If the RHZs ...

  14. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating.

    Science.gov (United States)

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-06-28

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.

  15. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating

    Science.gov (United States)

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-06-01

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.

  16. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering.

    Science.gov (United States)

    Zheng, Yun; Tan, Gangjian; Luo, Yubo; Su, Xianli; Yan, Yonggao; Tang, Xinfeng

    2017-06-06

    P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473-573 K) and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te₃ commercial zone-melting (ZM) ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS), and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te₃ compounds prepared by the MS-PAS technique.

  17. Comparative chemical genomics reveal that the spiroindolone antimalarial KAE609 (Cipargamin) is a P-type ATPase inhibitor

    Science.gov (United States)

    Goldgof, Gregory M.; Durrant, Jacob D.; Ottilie, Sabine; Vigil, Edgar; Allen, Kenneth E.; Gunawan, Felicia; Kostylev, Maxim; Henderson, Kiersten A.; Yang, Jennifer; Schenken, Jake; LaMonte, Gregory M.; Manary, Micah J.; Murao, Ayako; Nachon, Marie; Stanhope, Rebecca; Prescott, Maximo; McNamara, Case W.; Slayman, Carolyn W.; Amaro, Rommie E.; Suzuki, Yo; Winzeler, Elizabeth A.

    2016-01-01

    The spiroindolones, a new class of antimalarial medicines discovered in a cellular screen, are rendered less active by mutations in a parasite P-type ATPase, PfATP4. We show here that S. cerevisiae also acquires mutations in a gene encoding a P-type ATPase (ScPMA1) after exposure to spiroindolones and that these mutations are sufficient for resistance. KAE609 resistance mutations in ScPMA1 do not confer resistance to unrelated antimicrobials, but do confer cross sensitivity to the alkyl-lysophospholipid edelfosine, which is known to displace ScPma1p from the plasma membrane. Using an in vitro cell-free assay, we demonstrate that KAE609 directly inhibits ScPma1p ATPase activity. KAE609 also increases cytoplasmic hydrogen ion concentrations in yeast cells. Computer docking into a ScPma1p homology model identifies a binding mode that supports genetic resistance determinants and in vitro experimental structure-activity relationships in both P. falciparum and S. cerevisiae. This model also suggests a shared binding site with the dihydroisoquinolones antimalarials. Our data support a model in which KAE609 exerts its antimalarial activity by directly interfering with P-type ATPase activity. PMID:27291296

  18. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    This thesis reports on low temperature amorphous silicon back and front contacts for high-efficiency crystalline silicon solar cells with a p-type base. The back contact uses a sequence of intrinsic amorphous (i-a-Si:H) and boron doped microcrystalline (p-{mu}c-Si:H) silicon layers fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and a magnetron sputtered ZnO:Al layer. The back contact is finished by evaporating Al onto the ZnO:Al and altogether prepared at a maximum temperature of 220 C. Analysis of the electronic transport of mobile charge carriers at the back contact shows that the two high-efficiency requirements low back contact series resistance and high quality c-Si surface passivation are in strong contradiction to each other, thus difficult to achieve at the same time. The preparation of resistance- and effective lifetime samples allows one to investigate both requirements independently. Analysis of the majority charge carrier transport on complete Al/ZnO:Al/a-Si:H/c-Si back contact structures derives the resistive properties. Measurements of the effective minority carrier lifetime on a-Si:H coated wafers determines the back contact surface passivation quality. Both high-efficiency solar cell requirements together are analyzed in complete photovoltaic devices where the back contact series resistance mainly affects the fill factor and the back contact passivation quality mainly affects the open circuit voltage. The best cell equipped with a diffused emitter with random texture and a full-area a-Si:H/c-Si back contact has an independently confirmed efficiency {eta} = 21.0 % with an open circuit voltage V{sub oc} = 681 mV and a fill factor FF = 78.7 % on an area of 1 cm{sup 2}. An alternative concept that uses a simplified a-Si:H layer sequence combined with Al-point contacts yields a confirmed efficiency {eta} = 19.3 % with an open circuit voltage V{sub oc} = 655 mV and a fill factor FF = 79.5 % on an area of 2 cm{sup 2}. Analysis of the

  19. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    This thesis reports on low temperature amorphous silicon back and front contacts for high-efficiency crystalline silicon solar cells with a p-type base. The back contact uses a sequence of intrinsic amorphous (i-a-Si:H) and boron doped microcrystalline (p-{mu}c-Si:H) silicon layers fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and a magnetron sputtered ZnO:Al layer. The back contact is finished by evaporating Al onto the ZnO:Al and altogether prepared at a maximum temperature of 220 C. Analysis of the electronic transport of mobile charge carriers at the back contact shows that the two high-efficiency requirements low back contact series resistance and high quality c-Si surface passivation are in strong contradiction to each other, thus difficult to achieve at the same time. The preparation of resistance- and effective lifetime samples allows one to investigate both requirements independently. Analysis of the majority charge carrier transport on complete Al/ZnO:Al/a-Si:H/c-Si back contact structures derives the resistive properties. Measurements of the effective minority carrier lifetime on a-Si:H coated wafers determines the back contact surface passivation quality. Both high-efficiency solar cell requirements together are analyzed in complete photovoltaic devices where the back contact series resistance mainly affects the fill factor and the back contact passivation quality mainly affects the open circuit voltage. The best cell equipped with a diffused emitter with random texture and a full-area a-Si:H/c-Si back contact has an independently confirmed efficiency {eta} = 21.0 % with an open circuit voltage V{sub oc} = 681 mV and a fill factor FF = 78.7 % on an area of 1 cm{sup 2}. An alternative concept that uses a simplified a-Si:H layer sequence combined with Al-point contacts yields a confirmed efficiency {eta} = 19.3 % with an open circuit voltage V{sub oc} = 655 mV and a fill factor FF = 79.5 % on an area of 2 cm{sup 2}. Analysis of the

  20. Continuous auditing & continuous monitoring : Continuous value?

    NARCIS (Netherlands)

    van Hillo, Rutger; Weigand, Hans; Espana, S; Ralyte, J; Souveyet, C

    2016-01-01

    Advancements in information technology, new laws and regulations and rapidly changing business conditions have led to a need for more timely and ongoing assurance with effectively working controls. Continuous Auditing (CA) and Continuous Monitoring (CM) technologies have made this possible by obtain

  1. Continuous auditing & continuous monitoring : Continuous value?

    NARCIS (Netherlands)

    van Hillo, Rutger; Weigand, Hans; Espana, S; Ralyte, J; Souveyet, C

    2016-01-01

    Advancements in information technology, new laws and regulations and rapidly changing business conditions have led to a need for more timely and ongoing assurance with effectively working controls. Continuous Auditing (CA) and Continuous Monitoring (CM) technologies have made this possible by obtain

  2. Continuous auditing & continuous monitoring : Continuous value?

    NARCIS (Netherlands)

    van Hillo, Rutger; Weigand, Hans; Espana, S; Ralyte, J; Souveyet, C

    2016-01-01

    Advancements in information technology, new laws and regulations and rapidly changing business conditions have led to a need for more timely and ongoing assurance with effectively working controls. Continuous Auditing (CA) and Continuous Monitoring (CM) technologies have made this possible by

  3. Monolayer MoS2 Nanoribbons as a Promising Material for Both n-type and p-type Legs in Thermoelectric Generators

    Science.gov (United States)

    Arab, A.; Davydov, A. V.; Papaconstantopoulos, D. A.; Li, Q.

    2016-10-01

    First-principles calculations have been performed to study the thermoelectric properties of monolayer MoS2 armchair nanoribbons (ACNRs). The electronic behavior of nanoribbons is dominated by the presence of edge states that are dependent on the number of zigzag chains across the nanoribbon. In addition, it is found that the phonon thermal conductance of monolayer MoS2 ACNRs is smaller than monolayer films due to phonon edge scattering. This effect is more pronounced in narrower nanoribbons, which leads to a higher ZT value compared to a monolayer MoS2 sheet. The effects of sulfur vacancy and edge roughness on the thermoelectric properties of MoS2 ACNRs have also been studied. We found that edge roughness decreased ZT values compared to those of perfect nanoribbons, as its impact on electrical conductance is more severe than on phonon thermal conductance. Sulfur vacancy, however, improved ZT in some subbands. It is shown that ZT values as high as 4 for electron-doped and 3 for hole-doped nanoribbons can be achieved at T = 500 K. The ability to achieve high ZT values for both p-type and n-type nanoribbons makes monolayer MoS2 ACNR a promising candidate for future solid-state thermoelectric generators.

  4. The enhanced low resistance contacts and boosted mobility in two-dimensional p-type WSe2 transistors through Ar+ ion-beam generated surface defects

    Directory of Open Access Journals (Sweden)

    Dahye Kim

    2016-10-01

    Full Text Available We intentionally generated surface defects in WSe2 using a low energy argon (Ar+ ion-beam. We were unable to detect any changes in lattice structure through Raman spectroscopy as expected through simulation. Meanwhile, atomic force microscopy showed roughened surfaces with a high density of large protruding spots. Defect-activated Photoluminescence (PL revealed a binding energy reduction of the W 4f core level indicating significant amounts of defect generation within the bandgap of WSe2 even at the lowest studied 300 eV ion-beam energy. The intensity ratio increase of direct PL peak demonstrated the decoupling of surface layers, which behave like consecutive defective monolayers. Electrical measurements after post-irradiation showed p-type ohmic contacts regardless of the ion-beam energy. The resulting ohmic contact contributed to an increased on/off current ratio, mobility enhancement of around 350 cm2V-1s-1 from a few cm2V-1s-1 in pristine devices and electron conduction suppression. Further increased ion-beam energy over 700 eV resulted in a high shift of threshold voltage and diminished subthreshold slope due to increased surface roughness and boosted interface scattering. The origin of the ohmic contact behavior in p-type WSe2 is expected to be from chalcogen vacancy defects of a certain size which pins the Fermi level near the valence band minimum. An optimized ion-beam irradiation process could provide solutions for fabricating ohmic contacts to transition metal dichalcogenides.

  5. Growth and electrical properties of high-quality Mg-doped P-type A10.2Ga0.8N films

    Institute of Scientific and Technical Information of China (English)

    Zhou Xiaowei; Li Peixian; Xu Shengrui; Hao Yue

    2009-01-01

    The growth of high-performance Mg-doped p-type AlxGa1-xN(X=0.2)using metal-organic chemical vapor deposition is reported.The influence of growth conditions(growth temperature,magnesium flow,and thermal annealing temperature)on the electrical properties of Mg-doped p-type AlxGa1-xN(X=0.2)has been investigated.Using the optimized conditions,we obtained a minimum p-type resistivity of 0.71 Ωcm for p-type AlGaN with 20% Al fraction.

  6. Reduction of deep levels generated by ion implantation into n- and p-type 4H-SiC

    Science.gov (United States)

    Kawahara, Koutarou; Suda, Jun; Pensl, Gerhard; Kimoto, Tsunenobu

    2010-08-01

    The authors have investigated effects of thermal oxidation on deep levels in the whole energy range of the band gap of 4H-SiC by deep level transient spectroscopy. The deep levels are generated by ion implantation. The dominant defects in n-type samples after ion implantation and high-temperature annealing at 1700 °C are IN3 (Z1/2: EC-0.63 eV) and IN9 (EH6/7: EC-1.5 eV) in low-dose-implanted samples, and IN8 (EC-1.2 eV) in high-dose-implanted samples. These defects can remarkably be reduced by thermal oxidation at 1150 °C. In p-type samples, however, IP8 (HK4: EV+1.4 eV) survives and additional defects such as IP4 (HK0: EV+0.72 eV) appear after thermal oxidation in low-dose-implanted samples. In high-dose-implanted p-type samples, three dominant levels, IP5 (HK2: EV+0.85 eV), IP6 (EV+1.0 eV), and IP7 (HK3: EV+1.3 eV), are remarkably reduced by oxidation at 1150 °C. The dominant defect IP4 observed in p-type 4H-SiC after thermal oxidation can be reduced by subsequent annealing in Ar at 1400 °C. These phenomena are explained by a model that excess interstitials are generated at the oxidizing interface, which diffuse into the bulk region.

  7. P-type ZnO films by phosphorus doping using plasma immersion ion-implantation technique

    Science.gov (United States)

    Nagar, S.; Chakrabarti, S.

    2013-03-01

    ZnO has been a subject of intense research in the optoelectronics community owing to its wide bandgap (3.3eV) and large exciton binding energy (60meV). However, difficulty in doping it p-type posts a hindrance in fabricating ZnO-based devices. In order to make p-type ZnO films, phosphorus implantation, using plasma immersion ion-implantation technique (2kV, 900W, 10μs pulse width) for 30 seconds, was performed on ZnO thin film deposited by RF Magnetron Sputtering (Sample A). The implanted samples were subsequently rapid thermal annealed at 700°C and 1000°C (Samples B and C) in oxygen environment for 30 seconds. Low temperature (8K) photoluminescence spectra reveal dominant donor-bound exciton (D°X) peak at 3.36eV for samples A and B. However, for Sample B the peaks around 3.31eV and 3.22eV corresponding to the free electron-acceptor (FA) and donor to acceptor pair peaks (DAP) are also observed. A dominant peak around 3.35eV, corresponding to acceptor bound exciton (A°X) peak, is detected for Sample C along with the presence of FA and DAP peaks around 3.31eV and 3.22eV. Moreover, the deep level peak around 2.5eV is higher for Sample B which may be due to implantation and acceptor related defects. However, for Sample C, the deep level peaks are very weak compared to the near band edge peaks confirming that these peaks are mainly due to intrinsic defects and not related to acceptors. These results clearly show us a promising way to achieve p-type ZnO films using phosphorus doping.

  8. Nitrogen-monoxide gas-sensing properties of transparent p-type copper-oxide nanorod arrays

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soojeong; Kim, Hyojin; Kim, Dojin [Chungnam National University, Daejeon (Korea, Republic of)

    2015-01-15

    We report the nitrogen-monoxide (NO) gas-sensing properties of transparent p-type copper-oxide (CuO) nanorod arrays synthesized by using the hydrothermal method with a CuO nanoparticle seed layer deposited on a glass substrate via sputtering process. We synthesized polycrystalline CuO nanorods measuring 200 to 300 nm in length and 20 to 30 nm in diameter for three controlled molarity ratios of 1:1, 1:2 and 1:4 between copper nitrate trihydrate [Cu(NO{sub 2}){sub 2}·3H{sub 2}O] and hexamethylenetetramine (C{sub 6}H{sub 12}N{sub 4}). The crystal structures and morphologies of the synthesized CuO nanorod arrays were examined using grazing incidence X-ray diffraction and scanning electron microscopy. The gas-sensing measurements for NO gas in dry air indicated that the CuO nanorodarray-based gas sensors synthesized under hydrothermal condition at a molarity ratio of 1:2 showed the best gas sensing response to NO gas. These CuO nanorod-array gas sensors exhibited a highly sensitive response to NO gas, with a maximum sensitivity of about 650% for 10 ppm NO in dry air at an operating temperature of 100 .deg. C. These transparent p-type CuO nanorod-array gas sensors have shown a reversible and reliable response to NO gas over a range of operating temperatures. These results indicate certain potential use of p-type oxide semiconductor CuO nanorods as sensing materials for several types of gas sensors, including p - n junction gas sensors.

  9. Primary defect transformations in high-resistivity p-type silicon irradiated with electrons at cryogenic temperatures

    CERN Document Server

    Makarenko, L F; Korshunov, F P; Murin, L I; Moll, M

    2009-01-01

    It has been revealed that self-interstitials formed under low intensity electron irradiationin high resistivity p-type silicon can be retained frozen up to room temperature. Low thermal mobility of the self-interstitials suggests that Frenkelpair sinsilicon can be stable at temperatures of about or higher than 100K. A broad DLTS peak with activation energy of 0.14–0.17eV can be identified as related to Frenkel pairs. This peak anneals out at temperatures of 120 140K. Experimental evidences are presented that be coming more mobile under forwardcurrent injection the self-interstitials change their charge state to a less positive one.

  10. Thermoelectric properties of p-type Bi-Sb-Te compositionally graded thermoelectric materials with different barriers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to find more suitable materials as barriers and to improve the thermoelectric properties, p-type (BiSb)2Te3 (0.85, 0.9) two segments compositionally graded thermoelectric materials (CGTM) with different barriers were fabricated by conventional hot pressure method. Metals Fe, Co, Cu and Al were used as barriers between two segments. The effects of different barriers on thermoelectric properties of CGTM were investigated. The results show that metal Fe is more stable and suitable as the barrier.

  11. Growth and characterization of Czochralski-grown n and p-type GaAs for space solar cell substrates

    Science.gov (United States)

    Chen, R. T.

    1983-01-01

    Progress in LEC (liquid encapsulated Czochralski) crystal growth techniques for producing high-quality, 3-inch-diameter, n- and p-type GaAs crystals suitable for solar cell applications is described. The LEC crystals with low dislocation densities and background impurities, high electrical mobilities, good dopant uniformity, and long diffusion lengths were reproducibly grown through control of the material synthesis, growth and doping conditions. The capability for producing these large-area, high-quality substrates should positively impact the manufacturability of highly efficiency, low cost, radiation-hard GaAs solar cells.

  12. The influence of substrate and annealing temperatures on electrical properties of p-type ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C.Y. [Department of Mathematics and Physics, Shanghai Institute of technology, 120 Cao Bao Road, Shanghai 200235 (China)], E-mail: zhang_canyun@sit.edu.cn

    2009-01-15

    In this study, p-type ZnO films with excellent electrical properties were prepared by ultrasonic spray pyrolysis (USP) combining with a N-Al codoping technique. The influence of the substrate temperature and annealing temperature on electrical properties of ZnO films was investigated. The growth and doping process of ZnO films was explored by thermogravimetry, differential scanning calorimetry and mass spectrum (TG-DSC-MS) measurements. It is suggested that the variation of electrical properties of ZnO films with the substrate temperature and annealing temperature results from the removal of H element out of the films.

  13. Crystallization of P-type ATPases by the High Lipid-Detergent (HiLiDe) Method

    DEFF Research Database (Denmark)

    Sitsel, Oleg; Wang, Kaituo; Liu, Xiangyu;

    2016-01-01

    Determining structures of membrane proteins remains a significant challenge. A technique utilizing high lipid-detergent concentrations ("HiLiDe") circumvents the major bottlenecks of current membrane protein crystallization methods. During HiLiDe, the protein-lipid-detergent ratio is varied...... in a controlled way in order to yield initial crystal hits, which may be subsequently optimized by variation of the crystallization conditions and/or utilizing secondary detergents. HiLiDe preserves the advantages of classical lipid-based methods, yet is compatible with both the vapor diffusion and batch...... crystallization techniques. The method has been applied with particular success to P-type ATPases....

  14. Crystallization of P-type ATPases by the High Lipid-Detergent (HiLiDe) Method.

    Science.gov (United States)

    Sitsel, Oleg; Wang, Kaituo; Liu, Xiangyu; Gourdon, Pontus

    2016-01-01

    Determining structures of membrane proteins remains a significant challenge. A technique utilizing high lipid-detergent concentrations ("HiLiDe") circumvents the major bottlenecks of current membrane protein crystallization methods. During HiLiDe, the protein-lipid-detergent ratio is varied in a controlled way in order to yield initial crystal hits, which may be subsequently optimized by variation of the crystallization conditions and/or utilizing secondary detergents. HiLiDe preserves the advantages of classical lipid-based methods, yet is compatible with both the vapor diffusion and batch crystallization techniques. The method has been applied with particular success to P-type ATPases.

  15. Prediction and theoretical characterization of p-type organic semiconductor crystals for field-effect transistor applications.

    Science.gov (United States)

    Atahan-Evrenk, Sule; Aspuru-Guzik, Alán

    2014-01-01

    The theoretical prediction and characterization of the solid-state structure of organic semiconductors has tremendous potential for the discovery of new high performance materials. To date, the theoretical analysis mostly relied on the availability of crystal structures obtained through X-ray diffraction. However, the theoretical prediction of the crystal structures of organic semiconductor molecules remains a challenge. This review highlights some of the recent advances in the determination of structure-property relationships of the known organic semiconductor single-crystals and summarizes a few available studies on the prediction of the crystal structures of p-type organic semiconductors for transistor applications.

  16. Differentiation of Bulk and Surface Events in p-type Point-Contact Germanium Detectors for Light WIMP Searches

    CERN Document Server

    Li, H B

    2013-01-01

    The p-type point-contact germanium detectors are novel techniques offering kg-scale radiation sensors with sub-keV sensitivities. They have been used for light Dark Matter WIMPs searches and may have potential applications in neutrino physics. There are, however, anomalous surface behaviour which needs to be characterized and understood. We describe the methods and results of a research program whose goals are to identify the bulk and surface events via software pulse shape analysis techniques, and to devise calibration schemes to evaluate the selection efficiency factors. Efficiencies-corrected background spectra from the low-background facility at Kuo-Sheng Neutrino Laboratory are derived.

  17. Two-dimensional ferromagnet/semiconductor transition metal dichalcogenide contacts: p-type Schottky barrier and spin-injection control

    KAUST Repository

    Gan, Liyong

    2013-09-26

    We study the ferromagnet/semiconductor contacts formed by transition metal dichalcogenide monolayers, focusing on semiconducting MoS2 and WS2 and ferromagnetic VS2. We investigate the degree of p-type doping and demonstrate tuning of the Schottky barrier height by vertical compressive pressure. An analytical model is presented for the barrier heights that accurately describes the numerical findings and is expected to be of general validity for all transition metal dichalcogenide metal/semiconductor contacts. Furthermore, magnetic proximity effects induce a 100% spin polarization at the Fermi level in the semiconductor where the spin splitting increases up to 0.70 eV for increasing pressure.

  18. Electrical properties of n-type GaSb substrates and p-type GaSb buffer layers for InAs/InGaSb superlattice infrared detectors

    Energy Technology Data Exchange (ETDEWEB)

    Mitchel, W. C., E-mail: William.Mitchel.1@us.af.mil; Haugan, H. J.; Mou, Shin; Brown, G. J. [Air Force Research Laboratory, Materials & Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433 (United States); Elhamri, S.; Berney, R. [University of Dayton, Department of Physics, Dayton, Ohio 45469 (United States)

    2015-09-15

    Lightly doped n-type GaSb substrates with p-type GaSb buffer layers are the preferred templates for growth of InAs/InGaSb superlattices used in infrared detector applications because of relatively high infrared transmission and a close lattice match to the superlattices. We report here temperature dependent resistivity and Hall effect measurements of bare substrates and substrate-p-type buffer layer structures grown by molecular beam epitaxy. Multicarrier analysis of the resistivity and Hall coefficient data demonstrate that high temperature transport in the substrates is due to conduction in both the high mobility zone center Γ band and the low mobility off-center L band. High overall mobility values indicate the absence of close compensation and that improved infrared and transport properties were achieved by a reduction in intrinsic acceptor concentration. Standard transport measurements of the undoped buffer layers show p-type conduction up to 300 K indicating electrical isolation of the buffer layer from the lightly n-type GaSb substrate. However, the highest temperature data indicate the early stages of the expected p to n type conversion which leads to apparent anomalously high carrier concentrations and lower than expected mobilities. Data at 77 K indicate very high quality buffer layers.

  19. Electrical properties of n-type GaSb substrates and p-type GaSb buffer layers for InAs/InGaSb superlattice infrared detectors

    Directory of Open Access Journals (Sweden)

    W. C. Mitchel

    2015-09-01

    Full Text Available Lightly doped n-type GaSb substrates with p-type GaSb buffer layers are the preferred templates for growth of InAs/InGaSb superlattices used in infrared detector applications because of relatively high infrared transmission and a close lattice match to the superlattices. We report here temperature dependent resistivity and Hall effect measurements of bare substrates and substrate-p-type buffer layer structures grown by molecular beam epitaxy. Multicarrier analysis of the resistivity and Hall coefficient data demonstrate that high temperature transport in the substrates is due to conduction in both the high mobility zone center Γ band and the low mobility off-center L band. High overall mobility values indicate the absence of close compensation and that improved infrared and transport properties were achieved by a reduction in intrinsic acceptor concentration. Standard transport measurements of the undoped buffer layers show p-type conduction up to 300 K indicating electrical isolation of the buffer layer from the lightly n-type GaSb substrate. However, the highest temperature data indicate the early stages of the expected p to n type conversion which leads to apparent anomalously high carrier concentrations and lower than expected mobilities. Data at 77 K indicate very high quality buffer layers.

  20. Control of p-type and n-type thermoelectric properties of bismuth telluride thin films by combinatorial sputter coating technology

    Science.gov (United States)

    Goto, Masahiro; Sasaki, Michiko; Xu, Yibin; Zhan, Tianzhuo; Isoda, Yukihiro; Shinohara, Yoshikazu

    2017-06-01

    p- and n-type bismuth telluride thin films have been synthesized by using a combinatorial sputter coating system (COSCOS). The crystal structure and crystal preferred orientation of the thin films were changed by controlling the coating condition of the radio frequency (RF) power during the sputter coating. As a result, the p- and n-type films and their dimensionless figure of merit (ZT) were optimized by the technique. The properties of the thin films such as the crystal structure, crystal preferred orientation, material composition and surface morphology were analyzed by X-ray diffraction, energy-dispersive X-ray spectroscopy and atomic force microscopy. Also, the thermoelectric properties of the Seebeck coefficient, electrical conductivity and thermal conductivity were measured. ZT for n- and p-type bismuth telluride thin films was found to be 0.27 and 0.40 at RF powers of 90 and 120 W, respectively. The proposed technology can be used to fabricate thermoelectric p-n modules of bismuth telluride without any doping process.

  1. Thermoelectric Properties of P-type Skutterudites YbxFe3.5Ni0.5Sb12 (0.8 x 1)

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jung Y [GM R& D and Planning, Warren, Michigan; Ye, Zuxin [GM Research and Development Center; Tessema, M. [GM Research and Development Center; Waldo, R.A. [GM Research and Development Center; Salvador, James R. [GM R& D and Planning, Warren, Michigan; Yang, Jihui [General Motors Corporation; Cai, Wei [ORNL; Wang, Hsin [ORNL

    2012-01-01

    P-type skutterudites, with nominal compositions YbxFe3.5Ni0.5Sb12 (0.8 x 1), have been synthesized by induction melting with subsequent annealing, and their thermoelectric properties evaluated from 3.5 K to 745 K to assess their suitability for thermoelectric based waste heat recovery applications. We report results for the synthesis and measurements of Seebeck coefficient (S), electrical resistivity ( ), thermal conductivity ( ), Hall coefficient (RH), and effective mass (m*/m0) of YbxFe3.5Ni0.5Sb12 (0.8 x 1). Powder x-ray diffraction and electron probe microanalysis (EPMA) show that this system has a narrow filling fraction range of x ~ 0.84 to 0.86 for Yb in the crystallographic voids. All samples show positive RH for the entire temperature range studied with carrier concentrations ranging from 9.6 1020 to 2.8 1021 cm-3 at room temperature. Relatively high values of S result in high power factors up to 17 Wcm-1K-2 at room temperature. However, large values of and a sharp reduction in the S at high temperature due to bipolar conduction prevent the attainment of high thermoelectric figure of merit.

  2. Preparation and characterization of segmented p-type Ti0.3Zr0.35Hf0.35CoSb0.8Sn0.2/Ca3Co4O9

    DEFF Research Database (Denmark)

    Le, Thanh Hung; Han, Li; Stamate, Eugen

    Misfit-layered cobaltite Ca3Co4O9+δ is considered as good p-type thermoelectric material in high temperature region (950 - 1100 K), while half-Heusler (HH) Ti0.3Zr0.35Hf0.35CoSb0.8Sn0.2 is high performance p-type material at temperatures below 950 K. In this work, oxide Ca3Co4O9+δ is segmented...... with HH using an electrically conductive adhesive and brazing joining technique. The thermoelectric properties of the component materials as well as the interfacial resistance at high temperatures were characterized as a function of temperature up to 1100 K, and the results are discussed in details....

  3. Comparative studies on p-type CuI grown on glass and copper substrate by SILAR method

    Energy Technology Data Exchange (ETDEWEB)

    Dhere, Sunetra L.; Latthe, Sanjay S. [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra (India); Kappenstein, Charles [University of Poitiers, Laboratory of Catalysis in Organic Chemistry, LA CCO, UMR CNRS 6503, Poitiers-86000 (France); Mukherjee, S.K. [Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400085, Maharashtra India (India); Rao, A. Venkateswara, E-mail: avrao2012@gmail.com [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra (India)

    2010-04-01

    Depending upon the method of synthesis and the nature of substrate surface, there is variation in the physico-chemical properties of the material. Cuprous iodide films are deposited at room temperature on the glass and copper substrates by a simple SILAR method and the obtained results are compared. The p-type material with optical band gap 2.88 eV is found to be possessing face-centered cubic crystal structure with lattice parameter 6.134 A. We observed irregular particles for the CuI film on the glass substrate while patterned arrays of micro-rods with cabbage like tips on copper substrate, for the same preparative conditions. Also, the material deposited on copper is showing superhydrophobic nature (contact angle {approx}156{sup o}) while that on glass it is hydrophilic (contact angle {approx}88{sup o}). We have characterized the thin films by X-ray diffraction, scanning electron microscopy, surface roughness and contact angle measurement, thermoelectric power measurement and optical studies. This hydrophobic, p-type material with wide band gap will be helpful in the development of optoelectronic devices.

  4. Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

    Science.gov (United States)

    Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

    2016-08-31

    The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

  5. Effect of gate dielectrics on the performance of p-type Cu2O TFTs processed at room temperature

    KAUST Repository

    Al-Jawhari, Hala A.

    2013-12-01

    Single-phase Cu2O films with p-type semiconducting properties were successfully deposited by reactive DC magnetron sputtering at room temperature followed by post annealing process at 200°C. Subsequently, such films were used to fabricate bottom gate p-channel Cu2O thin film transistors (TFTs). The effect of using high-κ SrTiO3 (STO) as a gate dielectric on the Cu2O TFT performance was investigated. The results were then compared to our baseline process which uses a 220 nm aluminum titanium oxide (ATO) dielectric deposited on a glass substrate coated with a 200 nm indium tin oxide (ITO) gate electrode. We found that with a 150 nm thick STO, the Cu2O TFTs exhibited a p-type behavior with a field-effect mobility of 0.54 cm2.V-1.s-1, an on/off ratio of around 44, threshold voltage equaling -0.62 V and a sub threshold swing of 1.64 V/dec. These values were obtained at a low operating voltage of -2V. The advantages of using STO as a gate dielectric relative to ATO are discussed. © (2014) Trans Tech Publications, Switzerland.

  6. Search for Pauli Exclusion Principle Violating Atomic Transitions and Electron Decay with a P-type Point Contact Germanium Detector

    CERN Document Server

    Abgrall, N; Avignone, F T; Barabash, A S; Bertrand, F E; Bradley, A W; Brudanin, V; Busch, M; Buuck, M; Caldwell, A S; Chan, Y-D; Christofferson, C D; Chu, P -H; Cuesta, C; Detwiler, J A; Dunagan, C; Efremenko, Yu; Ejiri, H; Elliott, S R; Finnerty, P S; Galindo-Uribarri, A; Gilliss, T; Giovanetti, G K; Goett, J; Green, M P; Gruszko, J; Guinn, I S; Guiseppe, V E; Henning, R; Hoppe, E W; Howard, S; Howe, M A; Jasinski, B R; Keeter, K J; Kidd, M F; Konovalov, S I; Kouzes, R T; LaFerriere, B D; Leon, J; MacMullin, J; Martin, R D; Massarczyk, R; Meijer, S J; Mertens, S; Orrell, J L; O'Shaughnessy, C; Poon, A W P; Radford, D C; Rager, J; Rielage, K; Robertson, R G H; Romero-Romero, E; Shanks, B; Shirchenko, M; Suriano, A M; Tedeschi, D; Trimble, J E; Varner, R L; Vasilyev, S; Vetter, K; Vorren, K; White, B R; Wilkerson, J F; Wiseman, C; Xu, W; Yakushev, E; Yu, C -H; Yumatov, V; Zhitnikov, I

    2016-01-01

    A search for Pauli-exclusion-principle-violating K-alpha electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8x10^30 seconds at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the x-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8x10^30 seconds at 90 C.L. It is estimated that the MAJORANA DEMONSTRATOR, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76-Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

  7. Comparative studies on p-type CuI grown on glass and copper substrate by SILAR method

    Science.gov (United States)

    Dhere, Sunetra L.; Latthe, Sanjay S.; Kappenstein, Charles; Mukherjee, S. K.; Rao, A. Venkateswara

    2010-04-01

    Depending upon the method of synthesis and the nature of substrate surface, there is variation in the physico-chemical properties of the material. Cuprous iodide films are deposited at room temperature on the glass and copper substrates by a simple SILAR method and the obtained results are compared. The p-type material with optical band gap 2.88 eV is found to be possessing face-centered cubic crystal structure with lattice parameter 6.134 Å. We observed irregular particles for the CuI film on the glass substrate while patterned arrays of micro-rods with cabbage like tips on copper substrate, for the same preparative conditions. Also, the material deposited on copper is showing superhydrophobic nature (contact angle ˜156°) while that on glass it is hydrophilic (contact angle ˜88°). We have characterized the thin films by X-ray diffraction, scanning electron microscopy, surface roughness and contact angle measurement, thermoelectric power measurement and optical studies. This hydrophobic, p-type material with wide band gap will be helpful in the development of optoelectronic devices.

  8. P-stop isolation study of irradiated n-in-p type silicon strip sensors for harsh radiation environment

    CERN Document Server

    AUTHOR|(CDS)2084505

    2015-01-01

    In order to determine the most radiation hard silicon sensors for the CMS Experiment after the Phase II Upgrade in 2023 a comprehensive study of silicon sensors after a fluence of up to $1.5\\times10^{15} n_{eq}/cm^{2}$ corresponding to $3000 fb^{-1}$ after the HL-LHC era has been carried out. The results led to the decision that the future Outer Tracker (20~cm${<}R{<}$110~cm) of CMS will consist of n-in-p type sensors. This technology is more radiation hard but also the manufacturing is more challenging compared to p-in-n type sensors due to additional process steps in order to suppress the accumulation of electrons between the readout strips. One possible isolation technique of adjacent strips is the p-stop structure which is a p-type material implantation with a certain pattern for each individual strip. However, electrical breakdown and charge collection studies indicate that the process parameters of the p-stop structure have to be carefully calibrated in order to achieve a sufficient strip isolatio...

  9. High performance printed N and P-type OTFTs enabling digital and analog complementary circuits on flexible plastic substrate

    Science.gov (United States)

    Jacob, S.; Abdinia, S.; Benwadih, M.; Bablet, J.; Chartier, I.; Gwoziecki, R.; Cantatore, E.; van Roermund, A. H. M.; Maddiona, L.; Tramontana, F.; Maiellaro, G.; Mariucci, L.; Rapisarda, M.; Palmisano, G.; Coppard, R.

    2013-06-01

    This paper presents a printed organic complementary technology on flexible plastic substrate with high performance N and P-type Organic Thin Film Transistors (OTFTs), based on small-molecule organic semiconductors in solution. Challenges related to the integration of both OTFT types in a common complementary flow are addressed, showing the importance of surface treatments. Stability on single devices and on an elementary complementary digital circuit (ring oscillator) is studied, demonstrating that a robust and reliable flow with high electrical performances can be established for printed organic devices. These devices are used to manufacture several analog and digital building blocks. The design is carried out using a model specifically developed for this technology, and taking into account the parametric variability. High-frequency measurements of printed envelope detectors show improved speed performance, resulting from the high mobility of the OTFTs. In addition, a compact dynamic flip-flop and a low-offset comparator are demonstrated, thanks to availability of both n-type and p-type OTFTs in the technology. Measurement results are in good agreement with the simulations. The circuits presented establish a complete library of building blocks for the realization of a printed RFID tag.

  10. Perovskite LaRhO{sub 3} as a p-type active layer in oxide photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Masao, E-mail: masao.nakamura@riken.jp; Krockenberger, Yoshiharu [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Fujioka, Jun [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Kawasaki, Masashi; Tokura, Yoshinori [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan)

    2015-02-16

    Perovskite-type transition-metal oxides have a wide variety of physical properties and triggered intensive research on functional devices in the form of heteroepitaxial junctions. However, there is a missing component that is a p-type conventional band semiconductor. LaRhO{sub 3} (LRO) is one of very few promising candidates having its bandgap between filled t{sub 2g} and empty e{sub g} of Rh in low-spin state, but there has been no report on the synthesis of large-size single crystals or thin films. Here, we report on the junction properties of single-crystalline thin films of LRO grown on (110) oriented Nb-doped SrTiO{sub 3} substrates. The external quantum efficiency of the photo-electron conversion exceeds 1% in the visible-light region due to the wide depletion layer and long diffusion length of minority carriers in LRO. Clear indication of p-type band semiconducting character in a perovskite oxide of LRO will pave a way to explore oxide electronics of perovskite heterostructures.

  11. Performances of miniature microstrip detectors made on oxygen enriched p-type substrates after very high proton irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Casse, G. [Oliver Lodge Laboratory, Department of Physics, University of Liverpool, P.O. Box 147, Liverpool L69 3BX (United Kingdom)]. E-mail: gcasse@hep.ph.liv.ac.uk; Allport, P.P. [Oliver Lodge Laboratory, Department of Physics, University of Liverpool, P.O. Box 147, Liverpool L69 3BX (United Kingdom); Marti i Garcia, S. [IFIC CSIC, Edificio Institutos de Investigacion Apartado de Correos 22085 E-46071, Valencia-Spain (Spain); Lozano, M. [IMB-CNM (CSIC), Campus Universidad Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Turner, P.R. [Oliver Lodge Laboratory, Department of Physics, University of Liverpool, P.O. Box 147, Liverpool L69 3BX (United Kingdom)

    2004-12-11

    Silicon microstrip detectors with n-type implant read-out strips on FZ p-type bulk (n-in-p) show superior charge collection properties, after heavy irradiation, to the more standard p-strips in n-type silicon (p-in-n). It is also well established that oxygen-enriched n-type silicon substrates show better performance, in terms of degradation of the full depletion voltage after charged hadron irradiation, than the standard FZ silicon used for high energy physics detectors. Silicon microstrip detectors combining both the advantages of oxygenation and of n-strip read-out (n-in-n) have achieved high radiation tolerance to charged hadrons. The manufacturing of n-in-n detectors though requires double-sided processing, resulting in more complicated and expensive devices than standard p-in-n. A cheaper single-sided option, that still combines these advantages, is to use n-in-p devices. P-type FZ wafers have been oxygen-enriched by high temperature diffusion from an oxide layer and successfully used to process miniature (1x1 cm{sup 2}) microstrip detectors. These detectors have been irradiated with 24 GeV/c protons in the CERN/PS T7 irradiation area up to {approx}7.5x10{sup 15} cm{sup -2}. We report results with these irradiated detectors in terms of the charge collection efficiency as a function of the applied bias voltage.

  12. Performances of miniature microstrip detectors made on oxygen enriched p-type substrates after very high proton irradiation

    Science.gov (United States)

    Casse, G.; Allport, P. P.; Martí i Garcia, S.; Lozano, M.; Turner, P. R.

    2004-12-01

    Silicon microstrip detectors with n-type implant read-out strips on FZ p-type bulk (n-in-p) show superior charge collection properties, after heavy irradiation, to the more standard p-strips in n-type silicon (p-in-n). It is also well established that oxygen-enriched n-type silicon substrates show better performance, in terms of degradation of the full depletion voltage after charged hadron irradiation, than the standard FZ silicon used for high energy physics detectors. Silicon microstrip detectors combining both the advantages of oxygenation and of n-strip read-out (n-in-n) have achieved high radiation tolerance to charged hadrons. The manufacturing of n-in-n detectors though requires double-sided processing, resulting in more complicated and expensive devices than standard p-in-n. A cheaper single-sided option, that still combines these advantages, is to use n-in-p devices. P-type FZ wafers have been oxygen-enriched by high temperature diffusion from an oxide layer and succesfully used to process miniature (1×1 cm 2) microstrip detectors. These detectors have been irradiated with 24 GeV/c protons in the CERN/PS T7 irradiation area up to ˜7.5×10 15 cm -2. We report results with these irradiated detectors in terms of the charge collection efficiency as a function of the applied bias voltage.

  13. Characterization of a heavy metal translocating P-type ATPase gene from an environmental heavy metal resistance Enterobacter sp. isolate.

    Science.gov (United States)

    Chien, Chih-Ching; Huang, Chia-Hsuan; Lin, Yi-Wei

    2013-03-01

    Heavy metals are common contaminants found in polluted areas. We have identified a heavy metal translocating P-type ATPase gene (hmtp) via fosmid library and in vitro transposon mutagenesis from an Enterobacter sp. isolate. This gene is believed to participate in the bacterium's heavy metal resistance traits. The complete gene was identified, cloned, and expressed in a suitable Escherichia coli host cell. E. coli W3110, RW3110 (zntA::Km), GG48 (ΔzitB::Cm zntA::Km), and GG51 (ΔzitB::Cm) were used to study the possible effects of this gene for heavy metal (cadmium and zinc in particular) resistance. Among the E. coli strains tested, RW3110 and GG48 showed more sensitivity to cadmium and zinc compared to the wild-type E. coli W3110 and strain GG51. Therefore, strains RW3110 and GG48 were chosen for the reference hosts for further evaluation of the gene's effect. The results showed that expression of this heavy metal translocating P-type ATPase gene could increase the ability for zinc and cadmium resistance in the tested microorganisms.

  14. Chemical Vapor Deposition Growth of Degenerate p-Type Mo-Doped ReS2 Films and Their Homojunction.

    Science.gov (United States)

    Qin, Jing-Kai; Shao, Wen-Zhu; Xu, Cheng-Yan; Li, Yang; Ren, Dan-Dan; Song, Xiao-Guo; Zhen, Liang

    2017-05-10

    Substitutional doping of transition metal dichalcogenide two-dimensional materials has proven to be effective in tuning their intrinsic properties, such as band gap, transport characteristics, and magnetism. In this study, we realized substitutional doping of monolayer rhenium disulfide (ReS2) with Mo via chemical vapor deposition. Scanning transmission electron microscopy demonstrated that Mo atoms are successfully doped into ReS2 by substitutionally replacing Re atoms in the lattice. Electrical measurements revealed the degenerate p-type semiconductor behavior of Mo-doped ReS2 field effect transistors, in agreement with density functional theory calculations. The p-n diode device based on a doped ReS2 and ReS2 homojunction exhibited gate-tunable current rectification behaviors, and the maximum rectification ratio could reach up to 150 at Vd = -2/+2 V. The successful synthesis of p-type ReS2 in this study could largely promote its application in novel electronic and optoelectronic devices.

  15. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Abgrall, N.; Bradley, A.W.; Chan, Y.D.; Mertens, S.; Poon, A.W.P. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Arnquist, I.J.; Hoppe, E.W.; Kouzes, R.T.; LaFerriere, B.D.; Orrell, J.L. [Pacific Northwest National Laboratory, Richland, WA (United States); Avignone, F.T. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Barabash, A.S.; Konovalov, S.I.; Yumatov, V. [National Research Center ' ' Kurchatov Institute' ' Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bertrand, F.E.; Galindo-Uribarri, A.; Radford, D.C.; Varner, R.L.; White, B.R.; Yu, C.H. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Brudanin, V.; Shirchenko, M.; Vasilyev, S.; Yakushev, E.; Zhitnikov, I. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Busch, M. [Duke University, Department of Physics, Durham, NC (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); Buuck, M.; Cuesta, C.; Detwiler, J.A.; Gruszko, J.; Guinn, I.S.; Leon, J.; Robertson, R.G.H. [University of Washington, Department of Physics, Center for Experimental Nuclear Physics and Astrophysics, Seattle, WA (United States); Caldwell, A.S.; Christofferson, C.D.; Dunagan, C.; Howard, S.; Suriano, A.M. [South Dakota School of Mines and Technology, Rapid City, SD (United States); Chu, P.H.; Elliott, S.R.; Goett, J.; Massarczyk, R.; Rielage, K. [Los Alamos National Laboratory, Los Alamos, NM (United States); Efremenko, Yu. [University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Ejiri, H. [Osaka University, Research Center for Nuclear Physics, Ibaraki, Osaka (Japan); Finnerty, P.S.; Gilliss, T.; Giovanetti, G.K.; Henning, R.; Howe, M.A.; MacMullin, J.; Meijer, S.J.; O' Shaughnessy, C.; Rager, J.; Shanks, B.; Trimble, J.E.; Vorren, K.; Xu, W. [Triangle Universities Nuclear Laboratory, Durham, NC (United States); University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC (United States); Green, M.P. [North Carolina State University, Department of Physics, Raleigh, NC (United States); Oak Ridge National Laboratory, Oak Ridge, TN (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); Guiseppe, V.E.; Tedeschi, D.; Wiseman, C. [University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Jasinski, B.R. [University of South Dakota, Department of Physics, Vermillion, SD (United States); Keeter, K.J. [Black Hills State University, Department of Physics, Spearfish, SD (United States); Kidd, M.F. [Tennessee Tech University, Cookeville, TN (United States); Martin, R.D. [Queen' s University, Department of Physics, Engineering Physics and Astronomy, Kingston, ON (Canada); Romero-Romero, E. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Vetter, K. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); University of California, Department of Nuclear Engineering, Berkeley, CA (United States); Wilkerson, J.F. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC (United States)

    2016-11-15

    A search for Pauli-exclusion-principle-violating K{sub α} electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8 x 10{sup 30} s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8 x 10{sup 30} s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of {sup 76}Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation. (orig.)

  16. Structural studies of P-type ATPase–ligand complexes using an X-ray free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Bublitz, Maike; Nass, Karol; Drachmann, Nikolaj D.; Markvardsen, Anders J.; Gutmann, Matthias J.; Barends, Thomas R. M.; Mattle, Daniel; Shoeman, Robert L.; Doak, R. Bruce; Boutet, Sébastien; Messerschmidt, Marc; Seibert, Marvin M.; Williams, Garth J.; Foucar, Lutz; Reinhard, Linda; Sitsel, Oleg; Gregersen, Jonas L.; Clausen, Johannes D.; Boesen, Thomas; Gotfryd, Kamil; Wang, Kai-Tuo; Olesen, Claus; Møller, Jesper V.; Nissen, Poul; Schlichting, Ilme

    2015-06-11

    Membrane proteins are key players in biological systems, mediating signalling events and the specific transport ofe.g.ions and metabolites. Consequently, membrane proteins are targeted by a large number of currently approved drugs. Understanding their functions and molecular mechanisms is greatly dependent on structural information, not least on complexes with functionally or medically important ligands. Structure determination, however, is hampered by the difficulty of obtaining well diffracting, macroscopic crystals. Here, the feasibility of X-ray free-electron-laser-based serial femtosecond crystallography (SFX) for the structure determination of membrane protein–ligand complexes using microcrystals of various native-source and recombinant P-type ATPase complexes is demonstrated. The data reveal the binding sites of a variety of ligands, including lipids and inhibitors such as the hallmark P-type ATPase inhibitor orthovanadate. By analyzing the resolution dependence of ligand densities and overall model qualities, SFX data quality metrics as well as suitable refinement procedures are discussed. Even at relatively low resolution and multiplicity, the identification of ligands can be demonstrated. This makes SFX a useful tool for ligand screening and thus for unravelling the molecular mechanisms of biologically active proteins.

  17. Structural studies of P-type ATPase–ligand complexes using an X-ray free-electron laser

    Directory of Open Access Journals (Sweden)

    Maike Bublitz

    2015-07-01

    Full Text Available Membrane proteins are key players in biological systems, mediating signalling events and the specific transport of e.g. ions and metabolites. Consequently, membrane proteins are targeted by a large number of currently approved drugs. Understanding their functions and molecular mechanisms is greatly dependent on structural information, not least on complexes with functionally or medically important ligands. Structure determination, however, is hampered by the difficulty of obtaining well diffracting, macroscopic crystals. Here, the feasibility of X-ray free-electron-laser-based serial femtosecond crystallography (SFX for the structure determination of membrane protein–ligand complexes using microcrystals of various native-source and recombinant P-type ATPase complexes is demonstrated. The data reveal the binding sites of a variety of ligands, including lipids and inhibitors such as the hallmark P-type ATPase inhibitor orthovanadate. By analyzing the resolution dependence of ligand densities and overall model qualities, SFX data quality metrics as well as suitable refinement procedures are discussed. Even at relatively low resolution and multiplicity, the identification of ligands can be demonstrated. This makes SFX a useful tool for ligand screening and thus for unravelling the molecular mechanisms of biologically active proteins.

  18. Chemical fabrication of p-type Cu{sub 2}O transparent thin film using molecular precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Hiroki [Research Institute of Science and Technology, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 (Japan); Suzuki, Tatsuya [Department of Applied Chemistry and Chemical Engineering, Graduate School of Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 (Japan); Hara, Hiroki; Mochizuki, Chihiro; Takano, Ichiro; Honda, Tohru [Research Institute of Science and Technology, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 (Japan); Sato, Mitsunobu, E-mail: lccsato@cc.kogakuin.ac.jp [Research Institute of Science and Technology, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 (Japan)

    2012-11-15

    A transparent p-type Cu{sub 2}O thin film of 50 nm thickness was successfully fabricated by means of a solution-based process involving the thermal reaction of molecular precursor films spin-coated on a Na-free glass substrate. The precursor solution was prepared by the reaction of an isolated Cu{sup 2+} complex of ethylenediamine-N, N, N Prime , N Prime -tetraacetic acid with dibutylamine in ethanol. The Cu{sub 2}O thin films resulting from heat treatment of the precursor film at 450 Degree-Sign C for 10 min in Ar gas at a flow rate of 1.0 L min{sup -1} were characterized by X-ray diffraction which indicated a precise cubic lattice cell parameter of a = 0.4265(2) nm, with a crystallite size of 8(2) nm. X-ray photoelectron spectroscopy peaks, attributable to the O 1s and Cu 2p{sub 3/2} level of the Cu{sub 2}O film were found at 532.6 eV and 932.4 eV, respectively. An average grain size of the deposited Cu{sub 2}O particles of ca. 200 nm was observed via field-emission scanning electron microscopy. The optical band edge evaluated from the absorption spectrum of the Cu{sub 2}O transparent thin film was 2.3 eV, assuming a direct-transition semiconductor. Hall Effect measurements of the thin film indicated that the single-phase Cu{sub 2}O thin film is a typical p-type semiconductor, with a hole concentration of 1.7 Multiplication-Sign 10{sup 16} cm{sup -3} and hole mobility of 4.8 cm{sup 2} V{sup -1} s{sup -1} at ambient temperature. The activation energy from the valence band to the acceptor level determined from an Arrhenius plot was 0.34 eV. The adhesion strength of the thin film on the Na-free glass substrate was also determined as a critical load (Lc1) of 2.0 N by means of a scratch test. The method described is the first example of fabrication and characterization of a p-type Cu{sub 2}O transparent thin film by a wet process. -- Graphical abstract: The p-type Cu{sub 2}O transparent thin film was facilely fabricated on a Na-free grass substrate by a solution based

  19. Electrical Conductivity.

    Science.gov (United States)

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  20. A novel technique based on a plasma focus device for nano-porous gallium nitride formation on P-type silicon

    Science.gov (United States)

    Sharifi Malvajerdi, S.; Salar Elahi, A.; Habibi, M.

    2017-04-01

    A new deposition formation was observed with a Mather-type Plasma Focus Device (MPFD). MPFD was unitized to fabricate porous Gallium Nitride (GaN) on p-type Silicon (Si) substrate with a (100) crystal orientation for the first time in a deposition process. GaN was deposited on Si with 4 and 7 shots. The samples were subjected to a 3 phase annealing procedure. First, the semiconductors were annealed in the PFD with nitrogen plasma shots after their deposition. Second, a thermal chemical vapor deposition annealed the samples for 1 h at 1050 °C by nitrogen gas at a pressure of 1 Pa. Finally, an electric furnace annealed the samples for 1 h at 1150 °C with continuous flow of nitrogen. Porous GaN structures were observed by Field emission scanning electron microscopy and atomic force microscopy. Furthermore, X-Ray diffraction analysis was carried out to determine the crystallinity of GaN after the samples were annealed. Energy-Dispersive X-Ray Spectroscopy indicated the amount of gallium, nitrogen, and oxygen due to the self-oxidation of the samples. Photoluminescence spectroscopy revealed emissions at 2.94 eV and 3.39 eV, which shows that hexagonal wurtzite crystal structures were formed.

  1. Low p-type contact resistance by field-emission tunneling in highly Mg-doped GaN

    Science.gov (United States)

    Okumura, Hironori; Martin, Denis; Grandjean, Nicolas

    2016-12-01

    Mg-doped GaN with a net acceptor concentration (NA-ND) in the high 1019 cm-3 range was grown using ammonia molecular-beam epitaxy. Electrical properties of NiO contact on this heavily doped p-type GaN were investigated. A potential-barrier height of 0.24 eV was extracted from the relationship between NA-ND and the specific contact resistivity (ρc). We found that there is an optimum NA-ND value of 5 × 1019 cm-3 for which ρc is as low as 2 × 10-5 Ω cm2. This low ρc is ascribed to hole tunneling through the potential barrier at the NiO/p+-GaN interface, which is well accounted for by the field-emission model.

  2. Expression of a prokaryotic P-type ATPase in E. coli Plasma Membranes and Purification by Ni2+-affinity chromatography

    Directory of Open Access Journals (Sweden)

    Geisler Markus

    1998-01-01

    Full Text Available In order to characterize the P-type ATPase from Synechocystis 6803 [Geisler (1993 et al. J. Mol. Biol. 234, 1284] and to facilitate its purification, we expressed an N-terminal 6xHis-tagged version of the ATPase in an ATPase deficient E. coli strain. The expressed ATPase was immunodetected as a dominant band of about 97 kDa localized to the E. coli plasma membranes representing about 20-25% of the membrane protein. The purification of the Synecho-cystis 6xHis-ATPase by single-step Ni-affinity chromatography under native and denaturating conditions is described. ATPase activity and the formation of phosphointermediates verify the full function of the enzyme: the ATPase is inhibited by vanadate (IC50= 119 &mgr;M and the formation of phosphorylated enzyme intermediates shown by acidic PAGE depends on calcium, indicating that the Synechocystis P-ATPase functions as a calcium pump.

  3. Effect of Etching Time on Optical and Thermal Properties of p-Type Porous Silicon Prepared by Electrical Anodisation Method

    Directory of Open Access Journals (Sweden)

    Kasra Behzad

    2012-01-01

    Full Text Available The porous silicon (PSi layers were formed on p-type silicon (Si wafer. The six samples were anodised electrically with 30 mA/cm2 fixed current density for different etching times. The structural, optical, and thermal properties of porous silicon on silicon substrates were investigated by photoluminescence (PL, photoacoustic spectroscopy (PAS, and UV-Vis-NIR spectrophotometer. The thickness and porosity of the layers were measured using the gravimetric method. The band gap of the samples was measured through the photoluminescence (PL peak and absorption spectra, then they were compared. It shows that band gap value increases by raising the porosity. Photoacoustic spectroscopy (PAS was carried out for measuring the thermal diffusivity (TD of the samples.

  4. Very low surface recombination velocities on p-type silicon wafers passivated with a dielectric with fixed negative charge

    Energy Technology Data Exchange (ETDEWEB)

    Agostinelli, G.; Delabie, A.; Dekkers, H.F.W.; De Wolf, S.; Beaucarne, G. [IMEC vzw, Kapeldreef 75, Leuven (Belgium); Vitanov, P.; Alexieva, Z. [CL SENES, Sofia (Bulgaria)

    2006-11-23

    Surface recombination velocities as low as 10cm/s have been obtained by treated atomic layer deposition (ALD) of Al{sub 2}O{sub 3} layers on p-type CZ silicon wafers. Low surface recombination is achieved by means of field induced surface passivation due to a high density of negative charges stored at the interface. In comparison to a diffused back surface field, an external field source allows for higher band bending, that is, a better performance. While this process yields state of the art results, it is not suited for large-scale production. Preliminary results on an industrially viable, alternative process based on a pseudo-binary system containing Al{sub 2}O{sub 3} are presented, too. With this process, surface recombination velocities of 500-1000cm/s have been attained on mc-Si wafers. (author)

  5. Large-Scale Surfactant-Free Synthesis of p-Type SnTe Nanoparticles for Thermoelectric Applications

    Directory of Open Access Journals (Sweden)

    Guang Han

    2017-02-01

    Full Text Available A facile one-pot aqueous solution method has been developed for the fast and straightforward synthesis of SnTe nanoparticles in more than ten gram quantities per batch. The synthesis involves boiling an alkaline Na2SnO2 solution and a NaHTe solution for short time scales, in which the NaOH concentration and reaction duration play vital roles in controlling the phase purity and particle size, respectively. Spark plasma sintering of the SnTe nanoparticles produces nanostructured compacts that have a comparable thermoelectric performance to bulk counterparts synthesised by more time- and energy-intensive methods. This approach, combining an energy-efficient, surfactant-free solution synthesis with spark plasma sintering, provides a simple, rapid, and inexpensive route to p-type SnTe nanostructured materials.

  6. Characterization of micro-strip detectors made with high resistivity n- and p-type Czochralski silicon

    Energy Technology Data Exchange (ETDEWEB)

    Macchiolo, A. [INFN and Universita degli Studi di Florence (Italy)]. E-mail: Anna.Macchiolo@fi.infn.it; Borrello, L. [INFN and Universita degli Studi di Pisa (Italy); Boscardin, M. [ITC-IRST Trento, Povo, Trento (Italy); Bruzzi, M. [INFN and Universita degli Studi di Florence (Italy); Creanza, D. [INFN and Dipartimento Interateneo di Fisica, Bari (Italy); Dalla Betta, G.-F. [ITC-IRST Trento, Povo, Trento (Italy); DePalma, M. [INFN and Dipartimento Interateneo di Fisica, Bari (Italy); Focardi, E. [INFN and Universita degli Studi di Florence (Italy); Manna, N. [INFN and Dipartimento Interateneo di Fisica, Bari (Italy); Menichelli, D. [INFN and Universita degli Studi di Florence (Italy); Messineo, A. [INFN and Universita degli Studi di Pisa (Italy); Piemonte, C. [ITC-IRST Trento, Povo, Trento (Italy); Radicci, V. [INFN and Dipartimento Interateneo di Fisica, Bari (Italy); Ronchin, S. [ITC-IRST Trento, Povo, Trento (Italy); Scaringella, M. [INFN and Universita degli Studi di Florence (Italy); Segneri, G. [INFN and Universita degli Studi di Pisa (Italy); Sentenac, D. [INFN and Universita degli Studi di Pisa (Italy); Zorzi, N. [ITC-IRST Trento, Povo, Trento (Italy)

    2007-04-01

    The results of the pre- and post-irradiation characterization of n- and p-type magnetic Czochralski silicon micro-strip sensors are reported. This work has been carried out within the INFN funded SMART project aimed at the development of radiation-hard semiconductor detectors for the luminosity upgrade of the large Hadron collider (LHC). The detectors have been fabricated at ITC-IRST (Trento, Italy) on 4 in wafers and the layout contains 10 mini-sensors. The devices have been irradiated with 24 GeV/c and 26 MeV protons in two different irradiation campaigns up to an equivalent fluence of 3.4x10{sup 15} 1-MeV n/cm{sup 2}. The post-irradiation results show an improved radiation hardness of the magnetic Czochralski mini-sensors with respect to the reference float-zone sample.

  7. Understanding the effect of $n$-type and $p$-type doping in the channel of graphene nanoribbon transistor

    Indian Academy of Sciences (India)

    SUDHANSHU CHOUDHARY; VIKRAM SINGH

    2016-09-01

    In this paper, device performance of graphene nanoribbon field effect transistor (GNRFET) with different doping concentrations in different parts of the channel is reported. The study is performed by using atomistic simulations based on self-consistent solution of Schrodinger’s and Poisson’s equation within the non-equilibrium Green’s function formalism. The transfer and output characteristics suggest that device performance with $n$-type doping in the channel is better with smaller supply voltage compared to higher supply voltage. On increasing the $n$-type doping concentration, we obtained better on-current and output characteristics in comparison with undoped and $p$-type doped channel GNRFET. Further, we introduced step-doping profile in the graphene nanoribbon (GNR) channel and found that the device gives better on-current and good saturation condition when compared to undoped or uniformly-doped channel.

  8. The fabrication of Na doped p-type Zn1- x Mg x O films by pulsed laser deposition

    Science.gov (United States)

    Zhang, L. Q.; Zhang, Y. Z.; Ye, Z. Z.; Lin, S. S.; Lu, B.; He, H. P.; Chen, L. X.; Lu, J. G.; Jiang, J.; Wu, K. W.; Huang, J. Y.; Zhu, L. P.

    2012-01-01

    P-type Zn1- x Mg x O (0≤ x≤0.25) films are obtained through Na doping, as confirmed by repeated Hall-effect measurements and rectification behavior of p-Zn0.81Mg0.19O:Na/ n-Zn0.8Mg0.2O:Al quasi-homojunctions. The absorption and photoluminescence spectra indicate the band gap shifts to higher energy in linearly proportional to Mg content. Critically, X-ray diffraction (XRD) patterns reveal that the strain induced by Na doping can be counteracted through an appropriate content of Mg alloying. Both XRD data and Hall-effect data imply that the solubility of Na acceptor should be enhanced by alloying with Mg. The X-ray photoelectron spectrum (XPS) result indicates the existence of Na. Microstructure structure of the film is confirmed by high-resolution transmission electron microscope.

  9. Primary defect transformations in high-resistivity p-type silicon irradiated with electrons at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Makarenko, L.F., E-mail: makarenko@bsu.b [Department of Applied Mathematics and Computer Science, Belarusian State University, Independence Ave. 4, 220030 Minsk (Belarus); Lastovski, S.B.; Korshunov, F.P.; Murin, L.I. [Scientific-Practical Materials Research Centre of NAS of Belarus, Minsk (Belarus); Moll, M. [CERN, Geneva (Switzerland)

    2009-12-15

    It has been revealed that self-interstitials formed under low intensity electron irradiation in high resistivity p-type silicon can be retained frozen up to room temperature. Low thermal mobility of the self-interstitials suggests that Frenkel pairs in silicon can be stable at temperatures of about or higher than 100 K. A broad DLTS peak with activation energy of 0.14-0.17 eV can be identified as related to Frenkel pairs. This peak anneals out at temperatures of 120-140 K. Experimental evidences are presented that becoming more mobile under forward current injection the self-interstitials change their charge state to a less positive one.

  10. Selective growth of n-type nanoparticles on p-type semiconductors for Z-scheme photocatalysis.

    Science.gov (United States)

    Miyauchi, Masahiro; Nukui, Yuuya; Atarashi, Daiki; Sakai, Etsuo

    2013-10-09

    Nanoparticles of an n-type WO3 semiconductor were segregated on the surface of p-type CaFe2O4 particles by a heterogeneous nucleation process under controlled hydrothermal conditions. By use of this approach, WO3 nanoparticles were selectively deposited on the surface of CaFe2O4, resulting in a significant increase in the photocatalytic reaction rate of the WO3/CaFe2O4 composite for the decomposition of gaseous acetaldehyde under visible-light irradiation. The high visible-light activity of the WO3/CaFe2O4 composite was due to efficient charge recombination through the junctions that formed between the two semiconductors.

  11. Design and analysis of nanowire p-type MOSFET coaxially having silicon core and germanium peripheral channel

    Science.gov (United States)

    Yu, Eunseon; Cho, Seongjae

    2016-11-01

    In this work, a nanowire p-type metal-oxide-semiconductor field-effect transistor (PMOSFET) coaxially having a Si core and a Ge peripheral channel is designed and characterized by device simulations. Owing to the high hole mobility of Ge, the device can be utilized for high-speed CMOS integrated circuits, with the effective confinement of mobile holes in Ge by the large valence band offset between Si and Ge. Source/drain doping concentrations and the ratio between the Si core and Ge channel thicknesses are determined. On the basis of the design results, the channel length is aggressively scaled down by evaluating the primary DC parameters in order to confirm device scalability and low-power applicability in sub-10-nm technology nodes.

  12. Energy and angular anisotropy optimisation of a p-type diode for in vivo dosimetry in photon-beam radiotherapy.

    Science.gov (United States)

    Greene, Simon; Price, Robert A

    2005-01-01

    We present simulation work using the Monte Carlo code MCNPX that shows that there is a possibility of improving the silicon p-type diode as a radiation dosemeter, by altering the construction of the diode. Altering the diode die thickness can reduce the inherent angular anisotropy of the diode, with little effect on its energy response. Conversely, the contact material and geometry have a large impact on the energy response with little effect on the inherent angular anisotropy. By correct choice of contact material, the typical over-response -100 keV relative to the response at 60Co energy can be reduced from approximately 20 to 4. It is expected that further enhancements may be made with different geometries and materials.

  13. CoGeNT: A Search for Low-Mass Dark Matter using p-type Point Contact Germanium Detectors

    CERN Document Server

    Aalseth, C E; Colaresi, J; Collar, J I; Leon, J Diaz; Fast, J E; Fields, N E; Hossbach, T W; Knecht, A; Kos, M S; Marino, M G; Miley, H S; Miller, M L; Orrell, J L; Yocum, K M

    2013-01-01

    CoGeNT employs p-type point-contact (PPC) germanium detectors to search for Weakly Interacting Massive Particles (WIMPs). By virtue of its low energy threshold and ability to reject surface backgrounds, this type of device allows an emphasis on low-mass dark matter candidates (WIMP mass around 10 GeV/c2). We report on the characteristics of the PPC detector presently taking data at the Soudan Underground Laboratory, elaborating on aspects of shielding, data acquisition, instrumental stability, data analysis, and background estimation. A detailed background model is used to investigate the low energy excess of events previously reported, and to assess the possibility of temporal modulations in the low-energy event rate. We conclude that the technique is ideally suited to search for the annual modulation signature expected from dark matter particle interactions in the region of WIMP mass and coupling favored by the DAMA/LIBRA claim.

  14. Electronic structure of p type Delta doped systems; Estructura electronica de sistemas dopadas con Delta de tipo p

    Energy Technology Data Exchange (ETDEWEB)

    Gaggero S, L.M.; Perez A, R. [Departamento de Fisica de los Materiales, Universidad Nacional de Educacion a Distancia, Senda del Rey s/n, 28040 Madrid (Spain)

    1998-12-31

    We summarize of the results obtained for the electronic structure of quantum wells that consist in an atomic layer doped with impurities of p type. The calculations are made within the frame worth of the wrapper function approach to independent bands and with potentials of Hartree. We study the cases reported experimentally (Be in GaAs and B in Si). We present the levels of energy, the wave functions and the rate of the electronic population between the different subbands, as well as the dependence of these magnitudes with the density of impurities in the layer. The participation of the bans of heavy holes is analysed, light and split-off band in the total electronic population. The effect of the temperature is discussed and we give a possible qualitative explanation of the experimental optical properties. (Author)

  15. Multistrip synthetic single-crystal-diamond photodiode based on a p-type/intrinsic/Schottky metal transverse configuration

    Science.gov (United States)

    Ciancaglioni, I.; Marinelli, Marco; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.; Dolbnya, I.; Sawhney, K.; Tartoni, N.

    2011-04-01

    A synthetic multistrip single-crystal-diamond detector based on a p-type/intrinsic diamond/Schottky metal transverse configuration, operating at zero-bias voltage, was developed. The device was characterized at the Diamond Light Source synchrotron in Harwell (UK) under monochromatic high-flux X-ray beams from 6 to 20 keV and a micro-focused 10 keV beam with a spot size of ~3 μm. No significant pixel-to-pixel variation of both spectral responsivity and time response, high spatial resolution and good signal uniformity along each strip were found, suggesting the tested device structure as a promising sensor for X-ray and UV radiation imaging.

  16. Fabrication and Characterization of a Single Hole Transistor in p-type GaAs/AlGaAs Heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Lisa A [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Reno, John L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Hargett, Terry W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Most spin qubit research to date has focused on manipulating single electron spins in quantum dots. However, hole spins are predicted to have some advantages over electron spins, such as reduced coupling to host semiconductor nuclear spins and the ability to control hole spins electrically using the large spin-orbit interaction. Building on recent advances in fabricating high-mobility 2D hole systems in GaAs/AlGaAs heterostructures at Sandia, we fabricate and characterize single hole transistors in GaAs. We demonstrate p-type double quantum dot devices with few-hole occupation, which could be used to study the physics of individual hole spins and control over coupling between hole spins, looking towards eventual applications in quantum computing. Intentionally left blank

  17. Cross-section imaging and p-type doping assessment of ZnO/ZnO:Sb core-shell nanowires by scanning capacitance microscopy and scanning spreading resistance microscopy

    Science.gov (United States)

    Wang, Lin; Sallet, Vincent; Sartel, Corinne; Brémond, Georges

    2016-08-01

    ZnO/ZnO:Sb core-shell structured nanowires (NWs) were grown by the metal organic chemical vapor deposition method where the shell was doped with antimony (Sb) in an attempt to achieve ZnO p-type conduction. To directly investigate the Sb doping effect in ZnO, scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) were performed on the NWs' cross-sections mapping their two dimensional (2D) local electrical properties. Although no direct p-type inversion in ZnO was revealed, a lower net electron concentration was pointed out for the Sb-doped ZnO shell layer with respect to the non-intentionally doped ZnO core, indicating an evident compensating effect as a result of the Sb incorporation, which can be ascribed to the formation of Sb-related acceptors. The results demonstrate SCM/SSRM investigation being a direct and effective approach for characterizing radial semiconductor one-dimensional (1D) structures and, particularly, for the doping study on the ZnO nanomaterial towards its p-type realization.

  18. Cross-section imaging and p-type doping assessment of ZnO/ZnO:Sb core-shell nanowires by scanning capacitance microscopy and scanning spreading resistance microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin, E-mail: lin.wang@insa-lyon.fr; Brémond, Georges [Institut des Nanotechnologies de Lyon (INL), Université de Lyon, CNRS UMR 5270, INSA Lyon, Bat. Blaise Pascal, 7 Avenue, Jean Capelle, 69621 Villeurbanne (France); Sallet, Vincent; Sartel, Corinne [Groupe d' étude de la Matière Condensée (GEMaC), CNRS - Université de Versailles St Quentin en Yvelines, Université Paris-Saclay, 45 Avenue des Etats-Unis, 78035 Versailles (France)

    2016-08-29

    ZnO/ZnO:Sb core-shell structured nanowires (NWs) were grown by the metal organic chemical vapor deposition method where the shell was doped with antimony (Sb) in an attempt to achieve ZnO p-type conduction. To directly investigate the Sb doping effect in ZnO, scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) were performed on the NWs' cross-sections mapping their two dimensional (2D) local electrical properties. Although no direct p-type inversion in ZnO was revealed, a lower net electron concentration was pointed out for the Sb-doped ZnO shell layer with respect to the non-intentionally doped ZnO core, indicating an evident compensating effect as a result of the Sb incorporation, which can be ascribed to the formation of Sb-related acceptors. The results demonstrate SCM/SSRM investigation being a direct and effective approach for characterizing radial semiconductor one-dimensional (1D) structures and, particularly, for the doping study on the ZnO nanomaterial towards its p-type realization.

  19. IgG from Amyotrophic Lateral Sclerosis Patients Increases Current Through P-Type Calcium Channels in Mammalian Cerebellar Purkinje Cells and in Isolated Channel Protein in Lipid Bilayer

    Science.gov (United States)

    Llinas, R.; Sugimori, M.; Cherksey, B. D.; Smith, R. Glenn; Delbono, O.; Stefani, E.; Appel, S.

    1993-12-01

    The effect of the IgG from amyotrophic lateral sclerosis (ALS) patients was tested on the voltage-dependent barium currents (IBa) in mammalian dissociated Purkinje cells and in isolated P-type calcium channels in lipid bilayers. Whole cell clamp of Purkinje cells demonstrates that ALS IgG increases the amplitude of IBa without modifying their voltage kinetics. This increased IBa could be blocked by a purified nonpeptide toxin from Agelenopsis aperta venom (purified funnel-web spider toxin) or by a synthetic polyamine analog (synthetic funnel-web spider toxin) and by a peptide toxin from the same spider venom, ω-Aga-IVA. Similar results were obtained on single-channel recordings from purified P channel protein. The addition of ALS IgG increased single-channel IBa open time without affecting slope conductance. The results described above were not seen with normal human IgG nor with boiled ALS IgG. It is concluded that ALS IgG enhances inward current through P-type calcium channels. Since P-type Ca2+ channels are present in motoneuron axon terminals, we propose that the enhanced calcium current triggered by ALS IgG may contribute to neuronal damage in ALS.

  20. Current transport mechanism at metal-semiconductor nanoscale interfaces based on ultrahigh density arrays of p-type NiO nano-pillars.

    Science.gov (United States)

    Nandy, Suman; Gonçalves, Gonçalo; Pinto, Joana Vaz; Busani, Tito; Figueiredo, Vitor; Pereira, Luís; Paiva Martins, Rodrigo Ferrão; Fortunato, Elvira

    2013-12-07

    The present work focuses on a qualitative analysis of localised I-V characteristics based on the nanostructure morphology of highly dense arrays of p-type NiO nano-pillars (NiO-NPs). Vertically aligned NiO-NPs have been grown on different substrates by using a glancing angle deposition (GLAD) technique. The preferred orientation of as grown NiO-NPs was controlled by the deposition pressure. The NiO-NPs displayed a polar surface with a microscopic dipole moment along the (111) plane (Tasker's type III). Consequently, the crystal plane dependent surface electron accumulation layer and the lattice disorder at the grain boundary interface showed a non-uniform current distribution throughout the sample surface, demonstrated by a conducting AFM technique (c-AFM). The variation in I-V for different points in a single current distribution grain (CD-grain) has been attributed to the variation of Schottky barrier height (SBH) at the metal-semiconductor (M-S) interface. Furthermore, we observed that the strain produced during the NiO-NPs growth can modulate the SBH. Inbound strain acts as an external field to influence the local electric field at the M-S interface causing a variation in SBH with the NPs orientation. This paper shows that vertical arrays of NiO-NPs are potential candidates for nanoscale devices because they have a great impact on the local current transport mechanism due to its nanostructure morphology.

  1. N and Al co-doping as a way to p-type ZnO without post-growth annealing

    Science.gov (United States)

    Snigurenko, Dymitr; Guziewicz, Elzbieta; Krajewski, Tomasz A.; Jakiela, Rafal; Syryanyy, Yevgen; Kopalko, Krzysztof; Paszkowicz, Wojciech

    2016-12-01

    We demonstrate experimental results on p-type ZnO films grown by atomic layer deposition (ALD) and co-doped with aluminum and nitrogen (ANZO). The films were obtained at low temperature (100 °C) with different N to Al ratio and show conductivity type, which depends on the N and Al content. We applied the x-ray photoelectron spectroscopy in order to get insight into a chemical nature of dopants and we found three pronounced contributions of the N1s core level which appear at binding energies of 396.1, 397.4 and around 399 eV. Based on ANZO and undoped ZnO films, both grown by the ALD technique, the ZnO homojunction was obtained in one technological process without any post-growth high temperature processing. The rectification ratio as high as 4 × 104 at ± 2 V was achieved when an ultrathin Al2O3 layer was inserted between p- and n-type ZnO and a n-type ZnO buffer layer deposited on an insulating Si substrate was applied.

  2. Free-charge carrier parameters of n-type, p-type and compensated InN:Mg determined by Infrared Spectroscopic Ellipsometry

    CERN Document Server

    Schöche, S; Darakchieva, V; Wang, X; Yoshikawa, A; Wang, K; Araki, T; Nanishi, Y; Schubert, M

    2013-01-01

    Infrared spectroscopic ellipsometry is applied to investigate the free-charge carrier properties of Mg-doped InN films. Two representative sets of In-polar InN grown by molecular beam epitaxy with Mg concentrations ranging from $1.2\\times10^{17}$ cm$^{-3}$ to $8\\times10^{20}$ cm$^{-3}$ are compared. P-type conductivity is indicated for the Mg concentration range of $1\\times10^{18}$ cm$^{-3}$ to $9\\times10^{19}$ cm$^{-3}$ from a systematic investigation of the longitudinal optical phonon plasmon broadening and the mobility parameter in dependence of the Mg concentration. A parameterized model that accounts for the phonon-plasmon coupling is applied to determine the free-charge carrier concentration and mobility parameters in the doped bulk InN layer as well as the GaN template and undoped InN buffer layer for each sample. The free-charge carrier properties in the second sample set are consistent with the results determined in a comprehensive analysis of the first sample set reported earlier [Sch\\"oche et al., ...

  3. Studies on Microstructure and Thermoelectric Properties of p-Type Bi-Sb-Te Based Alloys by Gas Atomization and Hot Extrusion Processes

    Science.gov (United States)

    Park, Ki-Chan; Madavali, Babu; Kim, Eun-Bin; Koo, Kyung-Wan; Hong, Soon-Jik

    2016-10-01

    p-Type Bi2Te3 + 75% Sb2Te3 based thermoelectric materials were fabricated via gas atomization and the hot extrusion process. The gas atomized powder showed a clean surface with a spherical shape, and expanded in a wide particle size distribution (average particle size 50 μm). The phase of the fabricated extruded and R-extruded bars was identified using x-ray diffraction. The relative densities of both the extruded and R-extruded samples were measured by Archimedes principle with ˜98% relative density. The R-extruded bar exhibited finer grain microstructure than that of single extrusion process, which was attributed to a recrystallization mechanism during the fabrication. The R-extruded sample showed improved Vickers hardness compared to the extruded sample due to its fine grain microstructure. The electrical conductivity improved for the extruded sample whereas the Seebeck coefficient decreases due to its high carrier concentration. The peak power factor, ˜4.26 × 10-3 w/mK2 was obtained for the single extrusion sample, which is higher than the R-extrusion sample owing to its high electrical properties.

  4. Studies on Microstructure and Thermoelectric Properties of p-Type Bi-Sb-Te Based Alloys by Gas Atomization and Hot Extrusion Processes

    Science.gov (United States)

    Park, Ki-Chan; Madavali, Babu; Kim, Eun-Bin; Koo, Kyung-Wan; Hong, Soon-Jik

    2017-05-01

    p-Type Bi2Te3 + 75% Sb2Te3 based thermoelectric materials were fabricated via gas atomization and the hot extrusion process. The gas atomized powder showed a clean surface with a spherical shape, and expanded in a wide particle size distribution (average particle size 50 μm). The phase of the fabricated extruded and R-extruded bars was identified using x-ray diffraction. The relative densities of both the extruded and R-extruded samples were measured by Archimedes principle with ˜98% relative density. The R-extruded bar exhibited finer grain microstructure than that of single extrusion process, which was attributed to a recrystallization mechanism during the fabrication. The R-extruded sample showed improved Vickers hardness compared to the extruded sample due to its fine grain microstructure. The electrical conductivity improved for the extruded sample whereas the Seebeck coefficient decreases due to its high carrier concentration. The peak power factor, ˜4.26 × 10-3 w/mK2 was obtained for the single extrusion sample, which is higher than the R-extrusion sample owing to its high electrical properties.

  5. The lead acceptor in p-type natural 2H-polytype MoS2 crystals evidenced by electron paramagnetic resonance

    Science.gov (United States)

    Iacovo, S.; Stesmans, A.; Houssa, M.; Afanas'ev, V. V.

    2017-03-01

    A low-temperature (T  =  1.5-8 K) electron paramagnetic resonance study of p-type 2H-polytype natural MoS2 crystals reveals a previously unreported anisotropic signal of corresponding defect density (spin S  =  ½) ~5  ×  1014 cm-3. For the applied magnetic field B//c-axis, the response is comprised of a single central asymmetric Zeeman peak at zero-crossing g  =  2.102(1), amid a symmetrically positioned hyperfine doublet of splitting 6.6(2) G. Field angular observations reveal a two-branch g pattern, indicative of a defect of lower than axial symmetry, likely orthorhombic (C 2v). Based on the signal specifics, it is ascribed to a system of decoupled Pb impurities substituting for Mo, the defect operating as an acceptor, with estimated thermal activation energy  >10 meV. Supporting theoretical anticipation, the results pinpoint the conduct of the Pb impurity in layered MoS2.

  6. Conduct disorders

    NARCIS (Netherlands)

    Buitelaar, J.K.; Smeets, K.C.; Herpers, P.; Scheepers, F.; Glennon, J.; Rommelse, N.N.J.

    2013-01-01

    Conduct disorder (CD) is a frequently occurring psychiatric disorder characterized by a persistent pattern of aggressive and non-aggressive rule breaking antisocial behaviours that lead to considerable burden for the patients themselves, their family and society. This review paper updates diagnostic

  7. Contrasting the Role of Mg and Ba Doping on the Microstructure and Thermoelectric Properties of p-Type AgSbSe2.

    Science.gov (United States)

    Liu, Zihang; Shuai, Jing; Geng, Huiyuan; Mao, Jun; Feng, Yan; Zhao, Xu; Meng, Xianfu; He, Ran; Cai, Wei; Sui, Jiehe

    2015-10-21

    Microstructure has a critical influence on the mechanical and functional properties. For thermoelectric materials, deep understanding of the relationship of microstructure and thermoelectric properties will enable the rational optimization of the ZT value and efficiency. Herein, taking AgSbSe2 as an example, we first report a different role of alkaline-earth metal ions (Mg(2+) and Ba(2+)) doping in the microstructure and thermoelectric properties of p-type AgSbSe2. For Mg doping, it monotonously increases the carrier concentration and then reduces the electrical resistivity, leading to a substantially enhanced power factor in comparison to those of other dopant elements (Bi(3+), Pb(2+), Zn(2+), Na(+), and Cd(2+)) in the AgSbSe2 system. Meanwhile, the lattice thermal conductivity is gradually suppressed by point defects scattering. In contrast, the electrical resistivity first decreases and then slightly rises with the increased Ba-doping concentrations due to the presence of BaSe3 nanoprecipitates, exhibiting a different variation tendency compared with the corresponding Mg-doped samples. More significantly, the total thermal conductivity is obviously reduced with the increased Ba-doping concentrations partially because of the strong scattering of medium and long wavelength phonons via the nanoprecipitates, consistent with the theoretical calculation and analysis. Collectively, ZT value ∼1 at 673 K and calculated leg efficiency ∼8.5% with Tc = 300 K and Th = 673 K are obtained for both AgSb0.98Mg0.02Se2 and AgSb0.98Ba0.02Se2 samples.

  8. P型多系统萎缩的MRI表现%MRI Features of Multiple System Atrophy P Type

    Institute of Scientific and Technical Information of China (English)

    邝岚琼; 王小宜; 邢妩; 廖伟华; 谢芳芳; 那伟

    2012-01-01

    Objective To analyze the MRI features of the multiple system atrophy ( MSA) P,in order to provide ima-geology basis for clinical diagnosis. Materials and Methods MRI findings in 9 patients with MSA P type( parkinsonism in dominant multiple system atrophy) in XiangYa Hospital were analyzed retrospectively. Results Of 9 patients, 6 had abnormal findings in putamen, 4 had putamen atrophy, 2 had the long T2 signal of the putamen edge ( fissure sign) , and 3 had the putamen diffuse little long T1 & T2 signals, and 4 had the very long T, & very short T2 signals in outer back of putamen. Moreover, among these 6 patients, there was one case merely featured in the putamen atrophy and one in the very long T1 & very short T2 signal in the outer back of putamen, and the other 4 cases were found the abnormal changes in a variety of core shell overlap there. There were 5 cases of brain stem abnormalities, one with cross sign, and four with the whole brain stem atrophy (two were found the little long T1 & T2 signal concerning symmetry of the cerebellum feet). Hemisphere abnormalities were found in 3 cases, 3 cases of them were the atrophy of both bilateral frontal temporal parietal oc-cipitals, 2 cases atrophy of bilateral frontal lobes. Cerebellar hemisphere atrophy was found in two cases. Cross sign was found in late MSA P type,and FLAIR sequences facilitate the detection of abnormal signal. Conclusion MRI facilitates the clinical diagnosis of MSA P type.%目的 分析P型多系统萎缩(multiple system atrophy,MSA)的MRI特征,为临床诊断提供影像学依据.资料与方法 回顾性分析经临床诊断为MSA-P型9例患者的常规MRI资料.结果 9例中,6例壳核有异常发现,其中壳核萎缩4例,壳核边缘长T2信号(裂隙征)2例,壳核弥漫性稍长T1、稍长T2信号3例,壳核后外侧极长T1、极短T2信号4例.6例中,单纯表现为壳核萎缩及壳核后外侧极长T1、极短T2信号各1例,余4例为多种壳核异常改变重叠出现.5例脑

  9. Continuity theory

    CERN Document Server

    Nel, Louis

    2016-01-01

    This book presents a detailed, self-contained theory of continuous mappings. It is mainly addressed to students who have already studied these mappings in the setting of metric spaces, as well as multidimensional differential calculus. The needed background facts about sets, metric spaces and linear algebra are developed in detail, so as to provide a seamless transition between students' previous studies and new material. In view of its many novel features, this book will be of interest also to mature readers who have studied continuous mappings from the subject's classical texts and wish to become acquainted with a new approach. The theory of continuous mappings serves as infrastructure for more specialized mathematical theories like differential equations, integral equations, operator theory, dynamical systems, global analysis, topological groups, topological rings and many more. In light of the centrality of the topic, a book of this kind fits a variety of applications, especially those that contribute to ...

  10. Conduction apraxia.

    Science.gov (United States)

    Ochipa, C; Rothi, L J; Heilman, K M

    1994-01-01

    A left hemisphere damaged patient with ideomotor apraxia is described, whose performance on pantomime to verbal command was superior to pantomime imitation. His reception of these same gestures (gesture naming) was spared. This syndrome has been named conduction apraxia. To account for this selective impaired performance on gesture imitation, a separation of the representations for gesture production and reception is proposed and a non-lexical gesture processing route for gesture imitation is suggested. Images PMID:7931387

  11. Conduction apraxia.

    OpenAIRE

    Ochipa, C; Rothi, L J; Heilman, K M

    1994-01-01

    A left hemisphere damaged patient with ideomotor apraxia is described, whose performance on pantomime to verbal command was superior to pantomime imitation. His reception of these same gestures (gesture naming) was spared. This syndrome has been named conduction apraxia. To account for this selective impaired performance on gesture imitation, a separation of the representations for gesture production and reception is proposed and a non-lexical gesture processing route for gesture imitation is...

  12. In situ monitoring of stacking fault formation and its carrier lifetime mediation in p-type 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bin, E-mail: chenbinmse@gmail.com; Chen, Jun; Yao, Yuanzhao; Sekiguchi, Takashi [National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Matsuhata, Hirofumi; Okumura, Hajime [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan)

    2014-07-28

    Using the fine control of an electron beam (e-beam) in scanning electron microscopy with the capabilities of both electrical and optical imaging, the stacking fault (SF) formation together with its tuning of carrier lifetime was in situ monitored and investigated in p-type 4H-SiC homoepitaxial films. The SFs were formed through engineering basal plane dislocations with the energy supplied by the e-beam. The e-beam intensity required for the SF formation in the p-type films was ∼100 times higher than that in the n-type ones. The SFs reduced the minority-carrier lifetime in the p-type films, which was opposite to that observed in the n-type case. The reason for the peculiar SF behavior in the p-type 4H-SiC is discussed with the cathodoluminescence results.

  13. Metal Fluoride Inhibition of a P-type H+ Pump: STABILIZATION OF THE PHOSPHOENZYME INTERMEDIATE CONTRIBUTES TO POST-TRANSLATIONAL PUMP ACTIVATION

    National Research Council Canada - National Science Library

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    .... In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H(+)-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state...

  14. Effective surface passivation of p-type crystalline silicon with silicon oxides formed by light-induced anodisation

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jie, E-mail: j.cui@unsw.edu.au [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052 (Australia); Grant, Nicholas [Centre for Sustainable Energy Systems, Australian National University, Canberra, A.C.T. 0200 (Australia); Lennon, Alison [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052 (Australia)

    2014-12-30

    Highlights: • The surface passivation by anodic SiO{sub 2} formed by light-induced anodisation is investigated. • The anodic SiO{sub 2} grows lower temperatures with shorter growth times. After annealing in oxygen and then forming gas the effective minority carrier lifetime is increased to 150 μs. • It shows a very low positive Q{sub eff} of 3.4 × 10{sup 11} cm{sup −2}, a moderate D{sub it} of 6 × 10{sup 11} eV{sup −1} cm{sup −2}. • It has a very low leakage current density suggesting its application in solar cell as a functional dielectric. - Abstract: Electronic surface passivation of p-type crystalline silicon by anodic silicon dioxide (SiO{sub 2}) was investigated. The anodic SiO{sub 2} was grown by light-induced anodisation (LIA) in diluted sulphuric acid at room temperature, a process that is significantly less-expensive than thermal oxidation which is widely-used in silicon solar cell fabrication. After annealing in oxygen and then forming gas at 400 °C for 30 min, the effective minority carrier lifetime of 3–5 Ω cm, boron-doped Czochralski silicon wafers with a phosphorus-doped 80 Ω/□ emitter and a LIA anodic SiO{sub 2} formed on the p-type surface was increased by two orders of magnitude to 150 μs. Capacitance–voltage measurements demonstrated a very low positive charge density of 3.4 × 10{sup 11} cm{sup −2} and a moderate density of interface states of 6 × 10{sup 11} eV{sup −1} cm{sup −2}. This corresponded to a silicon surface recombination velocity of 62 cm s{sup −1}, which is comparable with values reported for other anodic SiO{sub 2} films, which required higher temperatures and longer growth times, and significantly lower than oxides grown by chemical vapour deposition techniques. Additionally, a very low leakage current density of 3.5 × 10{sup −10} and 1.6 × 10{sup −9} A cm{sup −2} at 1 and −1 V, respectively, was measured for LIA SiO{sub 2} suggesting its potential application as insulation layer in

  15. Investigation of Landau level spin reversal in (110) oriented p-type GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Isik, Nebile

    2009-09-01

    In this thesis, the Landau level crossing or anticrossing of hole levels has been investigated in p-type GaAs 400 Aa wide quantum wells. In magneto-transport measurements, this is evidenced with the presence of an anomalous peak in the longitudinal resistance measurements at {nu}=1. In the transversal resistance measurements, no signature of this anomalous peak is observed. By increasing the hole density in the quantum well by applying a top gate voltage, the position of the anomalous peak shifts to higher magnetic fields. At very high densities, anomalous peak disappears. By applying a back gate voltage, the electric field in the quantum well is tuned. A consequence is that the geometry of the quantum well is tuned from square to triangular. The anomalous peak position is shown to depend also on the back gate voltage applied. Temperature dependence of the peak height is consistent with thermal activation energy gap ({delta}/2= 135 {mu}eV). The activation energy gap as a function of the magnetic field has a parabolic like dependence, with the minimum of 135 {mu}eV at 4 T. The peak magnitude is observed to decrease with increasing temperature. An additional peak is observed at {nu}=2 minimum. This additional peak at {nu}=2 might be due to the higher Landau level crossing. The p-type quantum wells have been investigated by photoluminescence spectroscopy, as a function of the magnetic field. The polarization of the emitted light has been analyzed in order to distinguish between the transitions related to spin of electron {+-} 1/2 and spin of hole -+ 3/2. The transition energies of the lowest electron Landau levels with spin {+-} 1/2 and hole Landau levels with spin -+ 3/2 versus magnetic field show crossing at 4 T. The heavy hole Landau levels with spins {+-} 3/2 are obtained by the substraction of transition energies from the sum of lowest electron Landau level energy and the energy gap of GaAs. The heavy hole Landau levels show a crossing at 4 T. However, due to the

  16. Mixed conductivity in terbia-stabilized bismuth oxide

    NARCIS (Netherlands)

    Vinke, I.C.; Boukamp, B.A.; Vries, de K.J.; Burggraaf, A.J.

    1992-01-01

    The mixed conducting solid solution 0.75Bi2O3−0.25Tb4O7 (BT40) was studied by impedance techniques using ionically blocking electrodes. These measurements confirmed the p-type electronic conductivity suggested in literature. In air at temperatures between 600 and 900 K the ionic transference number

  17. Thermal stability of Ni/Ti/Al ohmic contacts to p-type 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hailong; Shen, Huajun, E-mail: shenhuajun@ime.ac.cn; Tang, Yidan; Bai, Yun; Liu, Xinyu [Microwave Device and IC Department, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); Zhang, Xufang [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wu, Yudong; Liu, Kean [Zhuzhou CSR Times Electric Co., Ltd, ZhuZhou 412001 (China)

    2015-01-14

    Low resistivity Ni/Ti/Al ohmic contacts on p-type 4H-SiC epilayer were developed, and their thermal stabilities were also experimentally investigated through high temperature storage at 600 °C for 100 h. The contact resistance of the Al/Ti/Ni/SiC contacts degraded in different degrees, and the contact morphology deteriorated with the increases of the average surface roughness and interface voids. X-ray spectra showed that Ni{sub 2}Si and Ti{sub 3}SiC{sub 2}, which were formed during ohmic contact annealing and contributed to low contact resistivity, were stable under high temperature storage. The existence of the TiAl{sub 3} and NiAl{sub 3} intermetallic phases was helpful to prevent Al agglomeration on the interface and make the contacts thermally stable. Auger electron spectroscopy indicated that the incorporation of oxygen at the surface and interface led to the oxidation of Al or Ti resulting in increased contact resistance. Also, the formation of these oxides roughened the surface and interface. The temperature-dependence of the specific contact resistance indicated that a thermionic field emission mechanism dominates the current transport for contacts before and after the thermal treatment. It suggests that the Ni/Ti/Al composite ohmic contacts are promising for SiC devices to be used in high temperature applications.

  18. Transition from negative to positive photoconductivity in p -type P b1 -xE uxTe films

    Science.gov (United States)

    Pirralho, M. J. P.; Peres, M. L.; Soares, D. A. W.; Braga, P. C. O.; Pena, F. S.; Fornari, C. I.; Rappl, P. H. O.; Abramof, E.

    2017-02-01

    We investigated the photoconductivity effect in p -type P b1 -xE uxTe films for x =0.01 , 0.02, 0.03, 0.05, and 0.06 at T =300 K . The measurements revealed a clear transition from negative to positive photoconductivity as the Eu content x is increased at room temperature. This transition is related to the metal-insulator transition that occurs due to the disorder originated from the introduction of Eu atoms and it is an Anderson transition. Our investigation found that, from the potential application point of view, the sample x =0.06 is more suitable, i.e., it presents an almost noise-free signal and the higher photoconductivity amplitude response. The photoconductive amplitude response for the sample with x =0.06 was investigated further in the temperature range of 77-300 K and, surprisingly, multiple additional transitions were observed with amplitudes that reached around 200 times the original value before illumination. We show that this anomalous behavior is a consequence of the generation and recombination rates between the bands and the 4 f level and a defect level located inside the band gap.

  19. Combinatorial discovery through a distributed outreach program: investigation of the photoelectrolysis activity of p-type Fe, Cr, Al oxides.

    Science.gov (United States)

    Rowley, John G; Do, Thanh D; Cleary, David A; Parkinson, B A

    2014-06-25

    We report the identification of a semiconducting p-type oxide containing iron, aluminum, and chromium (Fe2-x-yCrxAlyO3) with previously unreported photoelectrolysis activity that was discovered by an undergraduate scientist participating in the Solar Hydrogen Activity research Kit (SHArK) program. The SHArK program is a distributed combinatorial science outreach program designed to provide a simple and inexpensive way for high school and undergraduate students to participate in the search for metal oxide materials that are active for the photoelectrolysis of water. The identified Fe2-x-yCrxAlyO3 photoelectrolysis material possesses many properties that make it a promising candidate for further optimization for potential application in a photoelectrolysis device. In addition to being composed of earth abundant elements, the FeCrAl oxide material has a band gap of 1.8 eV. Current-potential measurements for Fe2-x-yCrxAlyO3 showed an open circuit photovoltage of nearly 1 V; however, the absorbed photon conversion efficiency for hydrogen evolution was low (2.4 × 10(-4) at 530 nm) albeit without any deposited hydrogen evolution catalyst. X-ray diffraction of the pyrolyzed polycrystalline thin Fe2-x-yCrxAlyO3 film on fluorine-doped tin oxide substrates shows a hexagonal phase (hematite structure) and scanning electron microscope images show morphology consisting of small crystallites.

  20. Low temperature acetone detection by p-type nano-titania thin film: Equivalent circuit model and sensing mechanism

    Science.gov (United States)

    Bhowmik, B.; Dutta, K.; Hazra, A.; Bhattacharyya, P.

    2014-09-01

    Undoped nanocrystalline anatase p-type TiO2 thin film was deposited by sol-gel method on thermally oxidized p-Si (2-5 Ω cm, ) substrates. The thin film was characterized by X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) to confirm the formation of nanocrystalline anatase titania and to determine the crystallite size (∼7 nm). The resistive sensor structure was fabricated employing two lateral Pd electrodes on top of the TiO2 sensing layer. The developed sensor was tested in the temperature range of 50-200 °C for the detection of low ppm acetone (0.5-50 ppm). The maximum response of ∼115% was obtained at 150 °C with response/recovery time of 14 s/22 s at 50 ppm acetone (in air). Moreover, the sensors were capable of detecting acetone as low as 0.5 ppm with acceptable response magnitude. As titania acetone sensors are mostly n-TiO2 based, the acetone sensing mechanism for p-TiO2 is yet to be established authentically. To address the issue, an equivalent circuit model, based on the corresponding band diagram of nanocrystalline p-TiO2 with Pd electrode, was developed to describe the electron transfer mechanism through grain, grain boundary and Pd electrode under the influence of acetone vapor.

  1. High performance p-type segmented leg of misfit-layered cobaltite and half-Heusler alloy

    DEFF Research Database (Denmark)

    Le, Thanh Hung; Van Nong, Ngo; Snyder, Gerald Jeffrey;

    2015-01-01

    In this study, a segmented p-type leg of doped misfit-layered cobaltite Ca2.8Lu0.15Ag0.05Co4O9+δ and half-Heusler Ti0.3Zr0.35Hf0.35CoSb0.8Sn0.2 alloy was fabricated and characterized. The thermoelectric properties of single components, segmented leg, and the electrical contact resistance...... of the joint part were measured as a function of temperature. The output power generation characteristics of segmented legs were characterized in air under various temperature gradients, DT, with the hot side temperature up to 1153 K. At ΔT ≈756 K, the maximum conversion efficiency reached a value of ∼5......%, which is about 65% of that expected from the materials without parasitic losses. The long-term stability investigation for two weeks at the hot and cold side temperatures of 1153/397 K shows that the segmented leg has good durability as a result of stable and low electrical resistance contacts. 2015...

  2. A New Method for the Quick Determination of S-Type and P-Type Habitable Zones in Binary Systems

    Science.gov (United States)

    Wang, Zhaopeng; Cuntz, Manfred

    2017-01-01

    More than 3500 exoplanets have been confirmed nowadays, including a very large number of planets discovered by the Kepler mission. Additional exoplanets are expected to be found by ongoing missions as, e.g., K2 as well as future missions such as TESS. Exoplanets, especially terrestrial planets, located in stellar habitable zones are drawing great attention from the community and the public at large due to their potential for hosting alien life - a prospect that makes the adequate determination of stellar habitable zones an important goal of exoplanetary research. In the local Galactic neighborhood, binary systems occur relatively frequently. Thus, it is the aim of my presentation to offer a method for the quick determination for the existence of habitable zones in binaries. Therefore, fitting formulas for binary habitable zones regarding both S-type and P-type star-planet configurations are provided. Based on previous work in the literature, a joint constraint regarding radiative habitable zones and planetary orbital stability limits is used. Models of stellar habitable zones utilize updated computations for planetary climate models as given by Kopparapu et al. (2013, 2014) [ApJ 765, 131; ApJL 787, L29]. Cases studies showing the quality of the fit formulas, as well as applications to observed systems, are presented as well.

  3. Screening of inorganic wide-bandgap p-type semiconductors for high performance hole transport layers in organic photovoltaic devices

    Science.gov (United States)

    Ginley, David; Zakutayev, Andriy; Garcia, Andreas; Widjonarko, Nicodemus; Ndione, Paul; Sigdel, Ajaya; Parilla, Phillip; Olson, Dana; Perkins, John; Berry, Joseph

    2011-03-01

    We will report on the development of novel inorganic hole transport layers (HTL) for organic photovoltaics (OPV). All the studied materials belong to the general class of wide-bandgap p-type oxide semiconductors. Potential candidates suitable for HTL applications include SnO, NiO, Cu2O (and related CuAlO2, CuCrO2, SrCu2O4 etc) and Co3O4 (and related ZnCo2O4, NiCo2O4, MgCo2O4 etc.). Materials have been optimized by high-throughput combinatorial approaches. The thin films were deposited by RF sputtering and pulsed laser deposition at ambient and elevated temperatures. Performance of the inorganic HTLs and that of the reference organic PEDOT:PSS HTL were compared by measuring the power conversion efficiencies and spectral responses of the P3HT/PCBM- and PCDTBT/PCBM-based OPV devices. Preliminary results indicate that Co3O4-based HTLs have performance comparable to that of our previously reported NiOs and PEDOT:PSS HTLs, leading to a power conversion efficiency of about 4 percent. The effect of composition and work function of the ternary materials on their performance in OPV devices is under investigation.

  4. An MCMC-based waveform analysis with p-type point contact detectors in the MAJORANA DEMONSTRATOR

    Science.gov (United States)

    Shanks, Benjamin; MAJORANA Collaboration

    2017-01-01

    Statistical signal processing can be a powerful tool for extracting as much information as possible from raw data. By fitting data to a physical model of signal generation on an event-by-event basis, it can be used to perform precise event reconstruction and enable efficient background rejection. Searches for neutrinoless double-beta decay must achieve extremely low backgrounds to reach sensitivities required for discovery, and so can benefit greatly from this analysis technique. The MAJORANA DEMONSTRATOR has implemented a Markov Chain Monte Carlo (MCMC) signal processing algorithm to fit waveforms from p-type point contact (PPC) germanium detectors. After a machine learning step to tune detector fields and electronics response parameters, the MCMC algorithm is able to reconstruct the time, energy and position of interactions within the PPC detector. The parameters estimated with this method will find many applications within the DEMONSTRATOR physics program, including background identification and rejection. This will prove important as the DEMONSTRATOR aims to reach its background goal of < 3 counts/tonne/yr in the region of interest. This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.

  5. Fabrication and Characterization of p-Type SnO Thin Film with High c-Axis Preferred Orientation

    Science.gov (United States)

    Pei, Yanli; Liu, Wuguang; Shi, Jingtao; Chen, Zimin; Wang, Gang

    2016-11-01

    p-Type tin monoxide (SnO) thin films with high c-axis preferred orientation have been fabricated on quartz substrate via electron-beam evaporation at 280°C. Subsequently, rapid thermal annealing (RTA) was performed in N2 atmosphere at 400°C to 800°C. Their structural, chemical, optical, and electrical properties were investigated by x-ray diffraction analysis, ultraviolet-visible spectroscopy, scanning electron microscopy, x-ray photoelectron spectroscopy, and Hall-effect measurements. The c-axis-oriented films of Sn-rich SnO presented excellent thermal stability up to RTA at 700°C. Both the crystallization and the hole Hall mobility were enhanced with increasing RTA temperature, with Hall mobility of 16 cm2 V-1 s-1 being obtained after RTA at 700°C. It was considered that the presence of defects and low scattering from grain boundaries contributed to this high Hall mobility. RTA annealing temperature above 700°C induced chemical reaction between SnO and the quartz substrate, with a change of the film to amorphous state with Sn4+ formation.

  6. Low specific contact resistance on epitaxial p-type 4H-SiC with a step-bunching surface

    Institute of Scientific and Technical Information of China (English)

    韩超; 张玉明; 宋庆文; 汤晓燕; 张义门; 郭辉; 王悦湖

    2015-01-01

    This paper reports the performances of Ti/Al based ohmic contacts fabricated on highly doped p-type 4H-SiC epitaxial layer which has a severe step-bunching surface. Different contact schemes are investigated based on the Al:Ti composition with no more than 50 at.%Al. The specific contact resistance (SCR) is obtained to be as low as 2.6 × 10−6Ω·cm2 for the bilayered Ti(100 nm)/Al(100 nm) contact treated with 3 min rapid thermal annealing (RTA) at 1000◦C. The microstructure analyses examined by physical and chemical characterization techniques reveal an alloy-assisted ohmic contact formation mechanism, i.e., a high degree of alloying plays a decisive role in forming the interfacial ternary Ti3SiC2 dominating the ohmic behavior of the Ti/Al based contact. Furthermore, a globally covered Ti3SiC2 layer with (0001)-oriented texture can be formed, regardless of the surface step bunching as well as its structural evolution during the metallization annealing.

  7. Tuning the surface Fermi level on p-type gallium nitride nanowires for efficient overall water splitting.

    Science.gov (United States)

    Kibria, M G; Zhao, S; Chowdhury, F A; Wang, Q; Nguyen, H P T; Trudeau, M L; Guo, H; Mi, Z

    2014-04-30

    Solar water splitting is one of the key steps in artificial photosynthesis for future carbon-neutral, storable and sustainable source of energy. Here we show that one of the major obstacles for achieving efficient and stable overall water splitting over the emerging nanostructured photocatalyst is directly related to the uncontrolled surface charge properties. By tuning the Fermi level on the nonpolar surfaces of gallium nitride nanowire arrays, we demonstrate that the quantum efficiency can be enhanced by more than two orders of magnitude. The internal quantum efficiency and activity on p-type gallium nitride nanowires can reach ~51% and ~4.0 mol hydrogen h(-1) g(-1), respectively. The nanowires remain virtually unchanged after over 50,000 μmol gas (hydrogen and oxygen) is produced, which is more than 10,000 times the amount of photocatalyst itself (~4.6 μmol). The essential role of Fermi-level tuning in balancing redox reactions and in enhancing the efficiency and stability is also elucidated.

  8. Study of nanoparticles TiO2 thin films on p-type silicon substrate using different alcoholic solvents

    Science.gov (United States)

    Muaz, A. K. M.; Hashim, U.; Arshad, M. K. Md.; Ruslinda, A. R.; Ayub, R. M.; Gopinath, Subash C. B.; Voon, C. H.; Liu, Wei-Wen; Foo, K. L.

    2016-07-01

    In this paper, sol-gel method spin coating technique is adopted to prepare nanoparticles titanium dioxide (TiO2) thin films. The prepared TiO2 sol was synthesized using titanium butoxide act as a precursor and subjected to deposited on the p-type silicon oxide (p-SiO2) and glass slide substrates under room temperature. The effect of different alcoholic solvents of methanol and ethanol on the structural, morphological, optical and electrical properties were systematically investigated. The coated TiO2 thin films were annealed in furnace at 773 K for 1 h. The structural properties of the TiO2 films were examined with X-ray Diffraction (XRD). From the XRD analysis, both solvents showing good crystallinity with anatase phase were the predominant structure. Atomic Force Microscopy (AFM) was employed to study the morphological of the thin films. The optical properties were investigated by Ultraviolet-visible (UV-Vis) spectroscopy were found that ethanol as a solvent give a higher optical transmittance if compare to the methanol solvent. The electrical properties of the nanoparticles TiO2 thin films were measured using two-point-probe technique.

  9. Enhancement of photocathodic stability of p-type copper(I) oxide electrodes by surface etching treatment

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Fumiaki, E-mail: amano@kitakyu-u.ac.jp [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Department of Chemical and Environmental Engineering, The University of Kitakyushu, Kitakyushu 808-0135 (Japan); Ebina, Toshihiro [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Ohtani, Bunsho [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2014-01-01

    The photoelectrochemical properties of electrodeposited p-type copper(I) oxide (Cu{sub 2}O) films were investigated using methyl viologen (MV{sup 2+}) as an electron acceptor. The pristine Cu{sub 2}O films were deactivated during the photocathodic reaction as a result of self-reduction, whereas the (111)-oriented Cu{sub 2}O films treated in an aqueous solution containing hexamethylenetetramine at pH 5 and 90 °C exhibited stable photocurrent for MV{sup 2+} reduction into the cation radical. Scanning electron microscope images showed that the treated films contained smaller crystal grains than untreated ones. X-ray photoelectron spectroscopy revealed that the treatment etched the thin layer of copper(II) oxide from the Cu{sub 2}O polycrystalline surface. Etching of the film surface enhanced the stability and steady-state photocurrent for photocathodic reduction of MV{sup 2+}, suggesting that the crystalline composition and structures exposed on the outermost surface of Cu{sub 2}O polycrystalline films have a considerable influence on the selectivity for the photocathodic reaction over self-reduction. - Highlights: • Photoelectrochemical reduction of methyl viologen by (111)-oriented Cu{sub 2}O thin films • Cu{sub 2}O films are etched using an aqueous solution containing hexamethylenetetramine. • Etching decreases crystal grain size and removes the thin layer of CuO. • Etching enhances the stability of Cu{sub 2}O photoelectrodes.

  10. Limits on the use of cobalt sulfide as anode of p-type dye-sensitized solar cells

    Science.gov (United States)

    Bonomo, Matteo; Congiu, Mirko; De Marco, Maria Letizia; Dowling, Denis P.; Di Carlo, Aldo; Graeff, Carlos F. O.; Dini, Danilo

    2017-06-01

    Thin films of cobalt sulfide (CoS) of thickness l  traditional platinized fluorine-doped indium oxide (Pt-FTO) due to the lower cost of the starting materials (Co salts) and the easier procedure of deposition onto large area substrates. The latter process was carried out via direct precipitation of CoS from aqueous solutions. The photoconversion efficiency (η) of the corresponding device was 0.07%. This value is about 35% less than the efficiency that is obtained with the analogous p-DSC employing the Pt-FTO anode (η  =  0.11). Unlike p-DSCs based on Pt-FTO anodes, the photoelectrochemical cells employing CoS electrodes showed that this anodic material was not able to sustain the photocurrent densities generated by P1-sensitized NiO at a given photopotential. Illumination of the p-DSCs with CoS anodes and P1-sensitized NiO cathodes actually induced the reverse bias of the photoelectrochemical cell with CoS behaving like a p-type semiconductor with no degeneracy. Dedicated to Professor Roberto Federici on the occasion of his retirement.

  11. P-type AlAs/[GaAs/AlAs] Semiconductor/Superlattice DBR Grown by MBE

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A p-type AlAs(70.2 nm)/16.5 period [GaAs(3 nm)/AlAs(0.7 nm)] semiconductor/superlatice distributed Bragg reflector (DBR) has been grown on n+-GaAs(100) substrate by V80H molecular beam epitaxy system. Experimental reflection spectrum shows that its central wavelength is 820 nm, with the peak reflectivity for 10-pair DBR of as high as 96 %, and the reflection bandwidth of as wide as 90 nm. We formed a 20×20 μm2 square mesa to measure the series resistance using wet chemical etching. From the measurement result, the series resistance of about 50 Ω is obtained at a moderate doping (3×1018 cm-3). Finally, the dependence of the resistance of the DBR on the temperature is analyzed. From the experimental result, it is found that the mechanism of the low series resistance of this kind of DBR may increase the tunneling current in the semiconductor/superlattice mirror structure, which will result in a decrease in series resistance.

  12. Thomas-Fermi approximation in two p-type delta-doped quantum wells in GaAs an Si

    Energy Technology Data Exchange (ETDEWEB)

    Gaggero-Sager, L. M. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico); M' Peko, J. C.; Perez Alvarez, R. [Universidad de La Habana, Ciudad Habana (Cuba)

    2001-04-01

    Thomas-Fermi calculations of the hole subband structure in two coupled p-type d-doped GaAs and Si quantum wells are carried out as a function of the impurity concentration and the distance l between them. A simple formula is obtained for the potential as a function of these two magnitudes by both types of systems. The numerical results for a double Be-{delta}-doped GaAs (double B-{delta}-doped Si) quantum well show that the energy levels degenerate for l{>=}300 A(l{>=}200 A) for an impurity concentration of 1 x 10{sup 1}3 cm{sup -2}. [Spanish] Presentamos calculos de la estructura de subbandas de huecos, utilizando la aproximacion de Thomas-Fermi para dos pozos cuanticos d-dopados tipo p en GaAs y Si, como funcion de la concentracion de impurezas y de la distancia l entre ambos para los dos tipos de sistemas. Los resultados numericos muestran que para un pozo doble de B-{delta}-dopado GaAs (pozo doble de B-{delta}-dopado Si) con una concentracion de 1 x 10{sup 1}3 cm{sup -2} los niveles estan degenerados para l{>=}300 A(l{>=}200 A).

  13. Conductivity Probe

    Science.gov (United States)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  14. Deposition of Na–N dual acceptor doped p-type ZnO thin films and fabrication of p-ZnO:(Na, N)/n-ZnO:Eu homojunction

    Energy Technology Data Exchange (ETDEWEB)

    Swapna, R., E-mail: swapna.ramella@yahoo.com; Santhosh Kumar, M.C., E-mail: santhoshmc@nitt.edu

    2013-09-20

    Highlights: • Low resistive and stable p-type ZnO films are fabricated by dual acceptor-doping. • The fabricated p-ZnO:(Na, N)/n-ZnO:Eu homojunction is characterized and discussed. • The fabricated ZnO homojunction shows good rectifying characteristics. • The fabricated ZnO homojunction is suitable for optoelectronic devices. -- Abstract: Sodium and nitrogen dual acceptor doped p-type ZnO (ZnO:(Na, N)) films have been prepared by spray pyrolysis technique at a substrate temperature of 623 K. The ZnO:(Na, N) films are grown at a fixed N doping concentration of 2 at.% and varying the nominal Na doping concentration from 0 to 8 at.%. The XRD results show that all the ZnO:(Na, N) films exhibited (0 0 2) preferential orientation. The EDX and elemental mapping analysis shows the presence and distribution of Zn, O, Na and N in the deposited films. The Hall measurement results demonstrate that the Na–N dual acceptor doped ZnO films show excellent p-type conduction. The p-type ZnO:(Na, N) films with comparatively low resistivity of 5.60 × 10{sup −2} Ω cm and relatively high carrier concentration of 3.15 × 10{sup 18} cm{sup −3} are obtained at 6 at.%. ZnO based homojunction is fabricated by depositing n-type layer (Eu doped ZnO) grown over the p-type layer ZnO:(Na, N). The current–voltage (I–V) characteristics measured from the two-layer structure show typical rectifying characteristics of p-n junction with a low turn on voltage of about 1.69 V. The ZnO:(Na, N) films exhibit a high transmittance (about >90%) and the average reflectance is 8.9% in the visible region. PL measurement shows near-band-edge (NBE) emission and deep-level (DL) emission in the ZnO:(Na, N) thin films.

  15. Fabrication of p-type SrCuSeF/n-type In2O3:Sn bilayer ohmic tunnel junction and its application to the back contact of CdS/CdTe solar cells

    Science.gov (United States)

    Kitabayashi, Shuya; Shiina, Yasuyoshi; Murata, Ayuki; Okamoto, Tamotsu; Wada, Takahiro

    2017-08-01

    To develop polycrystalline thin-film tandem solar cells, a SrCuSeF/In2O3:Sn (ITO) bilayer film was studied. The transparent p-type conductive SrCuSeF layer was deposited by pulsed laser deposition (PLD), and the n-type conductive ITO layer was deposited by RF sputtering. The SrCuSeF/ITO bilayer film showed ohmic I-V characteristics. A tunnel junction between the p-type SrCuSeF and n-type ITO layers was successfully formed because the p-type SrCuSeF and the n-type ITO layers had sufficiently high carrier concentrations. The SrCuSeF/ITO bilayer film was applied as the back contact of a CdS/CdTe solar cell. The photovoltaic performance of the CdS/CdTe solar cell depends considerably on the thickness of the SrCuSeF layer. The CdTe solar cell with a back contact of the SrCuSeF layer with a thickness of 34 nm and the ITO layer with a thickness of 200 nm showed a high conversion efficiency of 14.3% (V OC = 804 mV, J SC = 27.5 mA/cm2, and FF = 0.65). The conversion efficiency was much higher than that of the CdTe solar cell with the SrCuSeF single-layer back contact (11.6%) and that of the CdTe cell with the ITO single-layer back contact (2.75%).

  16. Quantum conductance in silicon quantum wires

    CERN Document Server

    Bagraev, N T; Klyachkin, L E; Malyarenko, A M; Gehlhoff, W; Ivanov, V K; Shelykh, I A

    2002-01-01

    The results of investigations of electron and hole quantum conductance staircase in silicon quantum wires are presented. The characteristics of self-ordering quantum wells of n- and p-types, which from on the silicon (100) surface in the nonequilibrium boron diffusion process, are analyzed. The results of investigations of the quantum conductance as the function of temperature, carrier concentration and modulation degree of silicon quantum wires are given. It is found out, that the quantum conductance of the one-dimensional channels is observed, for the first time, at an elevated temperature (T >= 77 K)

  17. Continuation calculus

    Directory of Open Access Journals (Sweden)

    Bram Geron

    2013-09-01

    Full Text Available Programs with control are usually modeled using lambda calculus extended with control operators. Instead of modifying lambda calculus, we consider a different model of computation. We introduce continuation calculus, or CC, a deterministic model of computation that is evaluated using only head reduction, and argue that it is suitable for modeling programs with control. It is demonstrated how to define programs, specify them, and prove them correct. This is shown in detail by presenting in CC a list multiplication program that prematurely returns when it encounters a zero. The correctness proof includes termination of the program. In continuation calculus we can model both call-by-name and call-by-value. In addition, call-by-name functions can be applied to call-by-value results, and conversely.

  18. Conducted Vasoreactivity

    DEFF Research Database (Denmark)

    Postnov, D. E.; Neganova, A Y; Sosnovtseva, Olga

    2015-01-01

    , the underlying mechanisms are debated. Here, we focus on dynamical aspects of the problem hypothesizing the existence of a bistability-powered mechanism for regenerative pulse transmission along the endothelium. Bistability implies that the cell can have two different stable resting potentials and can switch......Conducted vasodilation is part of the physiological response to increasing metabolic demand of the tissue. Similar responses can be elicited by focal electrical or chemical stimulation. Some evidence suggests an endothelial pathway for nondecremental transmission of hyperpolarizing pulses. However...... a theoretical analysis as well as numerical simulations of both single- and multiunit bistable systems mimicking endothelial cells to investigate the self-consistence and stability of the proposed mechanism. We find that the individual cell may switch readily between two stable potentials. An array of coupled...

  19. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Yasuhiro; Yu, Zhenrui; Morales-Acevedo, Arturo [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2000-07-01

    P-type poly-Si thin films prepared by low temperature aluminum-induced crystallization and doping are reported. The starting material was boron-doped a-Si:H prepared by PECVD on glass substrates. Aluminum layers with different thickness were evaporated on a-Si:H surface and conventional thermal annealing was performed at temperatures ranging from 300 to 550 Celsius degrees. XRD, SIMS, and Hall effect measurements were carried out to characterize the annealed Al could be crystallized at temperature as low as 300 Celsius degrees in 60 minutes. This material has high carrier concentration as well as high Hall mobility and can be used as a p-layer of seed layer for thin film poly-Si solar cells. The technique reported here is compatible with PECVD process. [Spanish] Se informa sobre la preparacion de peliculas delgadas tipo P y Poli-Si mediante la cristalizacion inducida de aluminio a baja temperatura y el dopado. El material inicial era de boro dopado y a-Si:H preparado PECVD sobre substratos de vidrio. Se evaporaron capas de aluminio de diferente espesor sobre una superficie de a-Si:H y se llevo a cabo un destemplado termico convencional a temperaturas que varian entre 300 y 500 grados Celsius. Se llevaron a cabo mediciones de XRB, SIMS y del efecto Hall para caracterizar el aluminio destemplado para que pudiera ser cristalizado a temperaturas tan bajas como 300 grados Celsius en 60 minutos. Este material tiene una alta concentracion portadora asi como una alta movilidad Hall y puede usarse como una capa de semilla para celdas solares de pelicula delgada Poli-Si. La tecnica reportada aqui es compatible con el proceso PECVD.

  20. Theoretical luminescence spectra in p-type quantum wells and superlattices based on InGaAsN

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Thiago Freire de; Rodrigues, Sara Cristina Pinto [Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE (Brazil). Dept. de Fisica; Silva Junior, Eronides Felisberto da [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Fisica; Sipahi, Guilherme Matos [Universidade de Sao Paulo (IFSC/USP), Sao Carlos, SP (Brazil). Inst. de Fisica; Scolfaro, Luisa Maria Ribeiro [Texas State University, San Marcos, TX (United States), Dept. of Physics

    2012-07-01

    Full text: In the past few years, the dilute nitride system, InGaAsN, is proposed as a good candidate for several device applications. InGaAsN is considered a promising material for laser devices working at 1:3 or 1:5{mu}m and high-efficiency multijunction solar cells. Incorporation of In and N into GaAs result in a strong redshift of the emission wavelength. Besides, the strain can be minimized since the opposite effect of In and N on the lattice constant enables lattice matching of InGaAsN on GaAs. However, despite their great potential for applications, the understanding of their physical properties is rather incomplete. In particular, the dominant mechanisms of light emission in these alloys and their dependence on the nitrogen composition are not well established. Such information is crucial not only for a better understanding of the optical properties of the nitrogen containing III-V alloys, but also for a better technological control of alloy formation and optimization light emission efficiency. Another point concerns to investigation in p-type doping in InGaAsN. This is of great importance since, for example, can improve the transport in HBT (Heterojunction Bipolar Transistors) devices. In this work we report on theoretical luminescence spectra calculations for p-doped GaAs/InGaAsN quantum wells and superlattices. The calculations are performed within the k-vector.p-vector method by solving the full 8 x 8 Kane Hamiltonian, generalized to treat different materials. Strain effects due the lattice mismatch between InGaAsN and GaAs are taken into account. By varying the acceptor concentration we analyze the effect of exchange-correlation, which plays an important role in profile potential and electronic transition. These results can explain several important aspects about optical properties in these systems. (author)

  1. Fine tuning of fluorene-based dye structures for high-efficiency p-type dye-sensitized solar cells.

    Science.gov (United States)

    Liu, Zonghao; Li, Wenhui; Topa, Sanjida; Xu, Xiaobao; Zeng, Xianwei; Zhao, Zhixin; Wang, Mingkui; Chen, Wei; Wang, Feng; Cheng, Yi-Bing; He, Hongshan

    2014-07-09

    We report on an experimental study of three organic push-pull dyes (coded as zzx-op1, zzx-op1-2, and zzx-op1-3) featuring one, two, and three fluorene units as spacers between donors and acceptors for p-type dye-sensitized solar cells (p-DSSC). The results show increasing the number of spacer units leads to obvious increases of the absorption intensity between 300 nm and 420 nm, a subtle increase in hole driving force, and almost the same hole injection rate from dyes to NiO nanoparticles. Under optimized conditions, the zzx-op1-2 dye with two fluorene spacer units outperforms other two dyes in p-DSSC. It exhibits an unprecedented photocurrent density of 7.57 mA cm(-2) under full sun illumination (simulated AM 1.5G light illumination, 100 mW cm(-2)) when the I(-)/I3(-) redox couple and commercial NiO nanoparticles were used as an electrolyte and a semiconductor, respectively. The cells exhibited excellent long-term stability. Theoretical calculations, impedance spectroscopy, and transient photovoltage decay measurements reveal that the zzx-op1-2 exhibits lower photocurrent losses, longer hole lifetime, and higher photogenerated hole density than zzx-op1 and zzx-op1-3. A dye packing model was proposed to reveal the impact of dye aggregation on the overall photovoltaic performance. Our results suggest that the structural engineering of organic dyes is important to enhance the photovoltaic performance of p-DSSC.

  2. Low specific contact resistance on epitaxial p-type 4H-SiC with a step-bunching surface

    Science.gov (United States)

    Han, Chao; Zhang, Yu-Ming; Song, Qing-Wen; Tang, Xiao-Yan; Zhang, Yi-Men; Guo, Hui; Wang, Yue-Hu

    2015-11-01

    This paper reports the performances of Ti/Al based ohmic contacts fabricated on highly doped p-type 4H-SiC epitaxial layer which has a severe step-bunching surface. Different contact schemes are investigated based on the Al:Ti composition with no more than 50 at.% Al. The specific contact resistance (SCR) is obtained to be as low as 2.6 × 10-6 Ω·cm2 for the bilayered Ti(100 nm)/Al(100 nm) contact treated with 3 min rapid thermal annealing (RTA) at 1000 °C. The microstructure analyses examined by physical and chemical characterization techniques reveal an alloy-assisted ohmic contact formation mechanism, i.e., a high degree of alloying plays a decisive role in forming the interfacial ternary Ti3SiC2 dominating the ohmic behavior of the Ti/Al based contact. Furthermore, a globally covered Ti3SiC2 layer with (0001)-oriented texture can be formed, regardless of the surface step bunching as well as its structural evolution during the metallization annealing. Project supported by the Key Specific Projects of Ministry of Education of China (Grant No. 625010101), the National Natural Science Foundation of China (Grant No. 61234006), the Natural Science Foundation of ShaanXi Province, China (Grant No. 2013JQ8012), the Doctoral Fund of Ministry of Education of China (Grant No. 20130203120017), and the Specific Project of the Core Devices, China (Grant No. 2013ZX0100100-004).

  3. Hadron-therapy beam monitoring: Towards a new generation of ultra-thin p-type silicon strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bouterfa, M.; Aouadi, K. [Inst. of Information and Communication Technologies, Electronics and Applied Mathematics ICTEAM, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Bertrand, D. [Particle Therapy Dept., Ion Beam Application IBA, 1348 Louvain-la-Neuve (Belgium); Olbrechts, B.; Delamare, R. [Inst. of Information and Communication Technologies, Electronics and Applied Mathematics ICTEAM, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Raskin, J. P.; Gil, E. C. [Institut de Recherche en Mathematique et Physique IRMP, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Flandre, D. [Inst. of Information and Communication Technologies, Electronics and Applied Mathematics ICTEAM, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium)

    2011-07-01

    Hadron-therapy has gained increasing interest for cancer treatment especially within the last decade. System commissioning and quality assurance procedures impose to monitor the particle beam using 2D dose measurements. Nowadays, several monitoring systems exist for hadron-therapy but all show a relatively high influence on the beam properties: indeed, most devices consist of several layers of materials that degrade the beam through scattering and energy losses. For precise treatment purposes, ultra-thin silicon strip detectors are investigated in order to reduce this beam scattering. We assess the beam size increase provoked by the Multiple Coulomb Scattering when passing through Si, to derive a target thickness. Monte-Carlo based simulations show a characteristic scattering opening angle lower than 1 mrad for thicknesses below 20 {mu}m. We then evaluated the fabrication process feasibility. We successfully thinned down silicon wafers to thicknesses lower than 10 {mu}m over areas of several cm{sup 2}. Strip detectors are presently being processed and they will tentatively be thinned down to 20 {mu}m. Moreover, two-dimensional TCAD simulations were carried out to investigate the beam detector performances on p-type Si substrates. Additionally, thick and thin substrates have been compared thanks to electrical simulations. Reducing the pitch between the strips increases breakdown voltage, whereas leakage current is quite insensitive to strips geometrical configuration. The samples are to be characterized as soon as possible in one of the IBA hadron-therapy facilities. For hadron-therapy, this would represent a considerable step forward in terms of treatment precision. (authors)

  4. Role of the P-Type ATPases, ATP7A and ATP7B in brain copper homeostasis

    Directory of Open Access Journals (Sweden)

    Jonathon eTelianidis

    2013-08-01

    Full Text Available Over the past two decades there have been significant advances in our understanding of copper homeostasis and the pathological consequences of copper dysregulation. Cumulative evidence is revealing a complex regulatory network of proteins and pathways that maintain copper homeostasis. The recognition of copper dysregulation as a key pathological feature in prominent neurodegenerative disorders such as Alzheimer’s, Parkinson’s and prion diseases has led to increased research focus on the mechanisms controlling copper homeostasis in the brain. The copper-transporting P-Type ATPases (copper-ATPases, ATP7A and ATP7B, are critical components of the copper regulatory network. Our understanding of the biochemistry and cell biology of these complex proteins has grown significantly since their discovery in 1993. They are large polytopic transmembrane proteins with six copper-binding motifs within the cytoplasmic N-terminal domain, eight transmembrane domains and highly conserved catalytic domains. These proteins catalyze ATP-dependent copper transport across cell membranes for the metallation of many essential cuproenzymes, as well as for the removal of excess cellular copper to prevent copper toxicity. A key functional aspect of these copper transporters is their copper-responsive trafficking between the trans-Golgi network and the cell periphery. ATP7A- and ATP7B-deficiency, due to genetic mutation, underlie the inherited copper transport disorders, Menkes and Wilson diseases, respectively. Their importance in maintaining brain copper homeostasis is underscored by the severe neuropathological deficits in these disorders. Herein we will review and update our current knowledge of these copper transporters in the brain and the central nervous system, their distribution and regulation, their role in normal brain copper homeostasis and how their absence or dysfunction contributes to disturbances in copper homeostasis and neurodegeneration.

  5. Pristine and Al-doped hematite printed films as photoanodes of p-type dye-sensitized solar cells

    Science.gov (United States)

    Congiu, Mirko; De Marco, Maria L.; Bonomo, Matteo; Nunes-Neto, Oswaldo; Dini, Danilo; Graeff, Carlos F. O.

    2017-01-01

    We hereby propose a non-expensive method for the deposition of pure and Al-doped hematite photoanodes in the configuration of thin films for the application of dye-sensitized solar cells (DSSC). The electrodes have been prepared from hematite nanoparticles that were obtained by thermal degradation of a chemical precursor. The particles have been used in the preparation of a paste, suitable for both screen printing and doctor blade deposition. The paste was then spread on fluorine-doped tin oxide (FTO) to obtain porous hematite electrodes. The electrodes have been sensitized using N3 and D5 dyes and were characterized through current/voltage curves under simulated sun light (1 sun, AM 1.5) with a Pt counter electrode. Al-doping of hematite showed interesting changes in the physical and electrochemical characteristics of sensitized photoanodes since we could notice the growth of AlFe2O4 (hercynite) as a secondary crystal phase into the oxides obtained by firing the mixtures of two chemical precursors at different molar ratios. Pure and Al-doped hematite electrodes have been used in a complete n-type DSSCs. The kinetics of charge transfer through the interface dye/electrolyte was studied and compared to that of a typical p-type DSSC based on NiO photocathodes sensitized with erythrosine B. The results suggest a potential application of both Fe2O3 and Fe2O3/AlFe2O4 as photoanodes of a tandem DSSC.

  6. Role of the P-Type ATPases, ATP7A and ATP7B in brain copper homeostasis.

    Science.gov (United States)

    Telianidis, Jonathon; Hung, Ya Hui; Materia, Stephanie; Fontaine, Sharon La

    2013-01-01

    Over the past two decades there have been significant advances in our understanding of copper homeostasis and the pathological consequences of copper dysregulation. Cumulative evidence is revealing a complex regulatory network of proteins and pathways that maintain copper homeostasis. The recognition of copper dysregulation as a key pathological feature in prominent neurodegenerative disorders such as Alzheimer's, Parkinson's, and prion diseases has led to increased research focus on the mechanisms controlling copper homeostasis in the brain. The copper-transporting P-type ATPases (copper-ATPases), ATP7A and ATP7B, are critical components of the copper regulatory network. Our understanding of the biochemistry and cell biology of these complex proteins has grown significantly since their discovery in 1993. They are large polytopic transmembrane proteins with six copper-binding motifs within the cytoplasmic N-terminal domain, eight transmembrane domains, and highly conserved catalytic domains. These proteins catalyze ATP-dependent copper transport across cell membranes for the metallation of many essential cuproenzymes, as well as for the removal of excess cellular copper to prevent copper toxicity. A key functional aspect of these copper transporters is their copper-responsive trafficking between the trans-Golgi network and the cell periphery. ATP7A- and ATP7B-deficiency, due to genetic mutation, underlie the inherited copper transport disorders, Menkes and Wilson diseases, respectively. Their importance in maintaining brain copper homeostasis is underscored by the severe neuropathological deficits in these disorders. Herein we will review and update our current knowledge of these copper transporters in the brain and the central nervous system, their distribution and regulation, their role in normal brain copper homeostasis, and how their absence or dysfunction contributes to disturbances in copper homeostasis and neurodegeneration.

  7. Characterization of stain etched p-type silicon in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mogoda, A.S., E-mail: awad_mogoda@hotmail.com [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt); Ahmad, Y.H.; Badawy, W.A. [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt)

    2011-04-15

    Research highlights: {yields} Stain etching of p-Si in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4} was investigated. {yields} The electrical conductivity of the etched Si surfaces was measured using impedance technique. {yields} Scanning electron microscope and energy disperse X-ray were used to analyze the etched surfaces. {yields} Etching in aqueous HF solution containing HNO{sub 3} led to formation of a porous silicon layer. {yields} The formation of the porous silicon layer in HF/KMnO{sub 4} was accompanied by deposition of K{sub 2}SiF{sub 6} on the pores surfaces. - Abstract: Stain etching of p-type silicon in hydrofluoric acid solutions containing nitric acid or potassium permanganate as an oxidizing agent has been examined. The effects of etching time, oxidizing agent and HF concentrations on the electrochemical behavior of etched silicon surfaces have been investigated by electrochemical impedance spectroscopy (EIS). An electrical equivalent circuit was used for fitting the impedance data. The morphology and the chemical composition of the etched Si surface were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques, respectively. A porous silicon layer was formed on Si etched in HF solutions containing HNO{sub 3}, while etching in HF solutions containing KMnO{sub 4} led to the formation of a porous layer and simultaneous deposition of K{sub 2}SiF{sub 6} inside the pores. The thickness of K{sub 2}SiF{sub 6} layer increases with increasing the KMnO{sub 4} concentration and decreases as the concentration of HF increases.

  8. The performance of Y2O3 as interface layer between La2O3 and p-type silicon substrate

    Directory of Open Access Journals (Sweden)

    Shulong Wang

    2016-11-01

    Full Text Available In this study, the performance of Y2O3 as interface layer between La2O3 and p-type silicon substrate is studied with the help of atomic layer deposition (ALD and magnetron sputtering technology. The surface morphology of the bilayer films with different structures are observed after rapid thermal annealing (RTA by atomic force microscopy (AFM. The results show that Y2O3/Al2O3/Si structure has a larger number of small spikes on the surface and its surface roughness is worse than Al2O3/Y2O3/Si structure. The reason is that the density of Si substrate surface is much higher than that of ALD growth Al2O3. With the help of high-frequency capacitance-voltage(C-V measurement and conductivity method, the density of interface traps can be calculated. After a high temperature annealing, the metal silicate will generate at the substrate interface and result in silicon dangling bond and interface trap charge, which has been improved by X-ray photoelectron spectroscopy (XPS and interface trap charge density calculation. The interface trapped charge density of La2O3/Al2O3/Si stacked gate structure is lower than that of La2O3/Y2O3/Si gate structure. If Y2O3 is used to replace Al2O3 as the interfacial layer, the accumulation capacitance will increase obviously, which means lower equivalent oxide thickness (EOT. Our results show that interface layer Y2O3 grown by magnetron sputtering can effectively ensure the interface traps near the substrate at relative small level while maintain a relative higher dielectric constant than Al2O3.

  9. Functional p-Type, Polymerized Organic Electrode Interlayer in CH₃NH₃PbI₃ Perovskite/Fullerene Planar Heterojunction Hybrid Solar Cells.

    Science.gov (United States)

    Chiang, Tsung-Yu; Fan, Gang-Lun; Jeng, Jun-Yuan; Chen, Kuo-Cheng; Chen, Peter; Wen, Ten-Chin; Guo, Tzung-Fang; Wong, Ken-Tsung

    2015-11-11

    Thermal curing of the styrene-functionalized 9,9-diarylfluorene-based triaryldiamine monomer (VB-DAAF) forms an ideal p-type organic electrode interlayer capable of resisting solvation of the polar precursor solution in fabricating methylammonium lead iodide (CH3NH3PbI3) perovskite/fullerene (C60) planar heterojunction hybrid solar cells. The polymerized VB-DAAF film exhibits a good energy level alignment with the valence-band-edge level of the CH3NH3PbI3 perovskite to facilitate the transport of holes. The large energy barrier to the conduction-band-edge level of the CH3NH3PbI3 perovskite effectively blocks electrons from reaching the positive electrode and reduces the photon energy loss due to recombination. The best-performing cell with the configuration of glass/indium-tin oxide/polymerized VB-DAAF/CH3NH3PbI3 perovskite/C60/bathocuproine/aluminum is free of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) layer to achieve an open-circuit voltage (VOC) = 1.02 V, a short-circuit current (JSC) = 18.92 mA/cm(2), and a fill factor (FF) = 0.78, corresponding to a power conversion efficiency (PCE) of 15.17% under standard 1 sun AM 1.5G simulated solar irradiation. The performance is much superior to the device applying the PSS interlayer with photovoltaic parameters of VOC = 0.85 V, JSC = 16.37 mA/cm(2), and FF = 0.74, corresponding to a PCE of 10.27%. Additionally, we had applied a UV-assisted process to polymerize the VB-DAAF film at relatively lower temperature and fabricate decent perovskite-based solar cells on the flexible substrate for real applications.

  10. Room temperature deposition of amorphous p-type CuFeO$_2$ and fabrication of CuFeO$_2$/n-Si heterojunction by RF sputtering method

    Indian Academy of Sciences (India)

    TAO ZHU; ZANHONG DENG; XIAODONG FANG; WEIWEI DONG; JINGZHEN SHAO; RUHUA TAO; SHIMAO WANG

    2016-06-01

    Transparent conducting amorphous p-type CuFeO$_2$ (CFO) thin film was prepared by radio-frequency (RF) magnetron sputtering method at room temperature using polycrystalline CuFeO$_2$ target. Amorphous structureof as-deposited film was confirmed by XRD. XPS analysis convinced that the chemical state of Cu$^{+}$ and Fe$^{3+}$ in the film, and the chemical composition of the thin films is close to the stoichiometry of CuFeO$^2$. Surface morphology of the film was analysed by SEM studies. p-type nature and concentration of carriers was investigated by Hall effect measurement. The p–n heterojunction in the structure of Al/n-Si/p-CuFeO$_2$/Al showed good rectifying behaviour with a forward and reverse currents ratio of 555 at 2 V. The turn-on voltage and reverse leakage current values were found to be 0.9 V and 4 $\\mu$A at $−$2 V. Further, the conduction mechanism of forward bias voltage was controlled by thermionic emission (TE) and trap-space charge limited current (TCLC) mechanisms.

  11. [Conduct disorders].

    Science.gov (United States)

    Stadler, Christina

    2014-05-01

    The diagnosis conduct disorder (CD) is characterized by aggressive (e.g., physical aggression) as well as nonaggressive symptoms (e.g., violation of rules, truancy). Conclusions regarding the course and prognosis, or recommendations for effective interventions, seem not to be equally valid for the whole patient group. DSM-IV-TR included subtyping age-of-onset as a prognostic criterion, even though the evidence base for subtyping from age of onset was rather sparse. The relevant literature on CD has grown substantially since the publication of DSM-IV-TR in 1994. For the new DSM-5 edition, some important issues were discussed, for example, consideration of personality traits, female-specific or dimensional criteria, and adding a childhood-limited subtype (Moffitt et al., 2008). Nevertheless, the diagnostic protocol for CD was not changed in the most parts in the new edition of the DSM-5; the addition of a CD specifier with limited emotions is the most relevant change. On the basis of the existing evidence base, this review discusses whether the modifications in DSM-5 are helpful for fulfilling the requirements of a reliable and valid psychiatric classification.

  12. Evolution of the P-type II ATPase gene family in the fungi and presence of structural genomic changes among isolates of Glomus intraradices

    Directory of Open Access Journals (Sweden)

    Sanders Ian R

    2006-03-01

    Full Text Available Abstract Background The P-type II ATPase gene family encodes proteins with an important role in adaptation of the cell to variation in external K+, Ca2+ and Na2+ concentrations. The presence of P-type II gene subfamilies that are specific for certain kingdoms has been reported but was sometimes contradicted by discovery of previously unknown homologous sequences in newly sequenced genomes. Members of this gene family have been sampled in all of the fungal phyla except the arbuscular mycorrhizal fungi (AMF; phylum Glomeromycota, which are known to play a key-role in terrestrial ecosystems and to be genetically highly variable within populations. Here we used highly degenerate primers on AMF genomic DNA to increase the sampling of fungal P-Type II ATPases and to test previous predictions about their evolution. In parallel, homologous sequences of the P-type II ATPases have been used to determine the nature and amount of polymorphism that is present at these loci among isolates of Glomus intraradices harvested from the same field. Results In this study, four P-type II ATPase sub-families have been isolated from three AMF species. We show that, contrary to previous predictions, P-type IIC ATPases are present in all basal fungal taxa. Additionally, P-Type IIE ATPases should no longer be considered as exclusive to the Ascomycota and the Basidiomycota, since we also demonstrate their presence in the Zygomycota. Finally, a comparison of homologous sequences encoding P-type IID ATPases showed unexpectedly that indel mutations among coding regions, as well as specific gene duplications occur among AMF individuals within the same field. Conclusion On the basis of these results we suggest that the diversification of P-Type IIC and E ATPases followed the diversification of the extant fungal phyla with independent events of gene gains and losses. Consistent with recent findings on the human genome, but at a much smaller geographic scale, we provided evidence

  13. Characterization and Stability of Na-doped p-type ZnO Thin Films Preparation by Reactive DC Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    JI Zhen-guo; LIU Fang; HE Hai-yan; HAN Wei-zhi

    2009-01-01

    Na-doped p-type ZnO thin films have been realized by DC reactive magnetron sputtering with a set of metal-Zn targets doped with various Na contents and under different substrate temperatures,respectively.Hall effect measurement,field-emission SEM,X-ray diffraction and optical transmission were carried out to investigate the effects of Na content and substrate temperature on the properties of p-type films. Results indicate that all the Na-doped ZnO films are strongly (002) oriented,and have an average transmittance ~85% in the visible region.Na-doped p-type ZnO films with good structural,electrical,and optical properties can only be obtained at an intermediate amount of Na content and under appropriate substrate temperature.At the optimal condition,the Na-doped p-type ZnO has the lowest resistivity of 13.8Ω· cm with the carrier concentration as high as 1.07×10~(18) cm~(-3).The stability of the Na-doped p-type ZnO is also studied in this paper and it is found that the electrical properties keep stable in a period of one month.

  14. CuS p- type thin film characterization deposited on Ti, ITO and glass substrates using spray pyrolysis deposition (SPD) for light emitting diode (LED) application

    Science.gov (United States)

    Sabah, Fayroz A.; Ahmed, Naser M.; Hassan, Z.; Rasheed, Hiba S.; Azzez, Shrook A.; Al-Hazim, Nabeel Z.

    2016-07-01

    The copper sulphide (CuS) thin films were grown with good adhesion by spray pyrolysis deposition (SPD) on Ti, ITO and glass substrates at 200 °C. The distance between nozzle and substrate is 30 cm. The composition was prepared by mixing copper chloride CuCl2.2H2O as a source of Cu2+ and sodium thiosulfate Na2S2O3.5H2O as a source of and S2-. Two concentrations (0.2 and 0.4 M) were used for each CuCl2 and Na2S2O3 to be prepared and then sprayed (20 ml). The process was started by spraying the solution for 3 seconds and after 10 seconds the cycle was repeated until the solution was sprayed completely on the hot substrates. The structural characteristics were studied using X-ray diffraction; they showed covellite CuS hexagonal crystal structure for 0.2 M concentration, and covellite CuS hexagonal crystal structure with two small peaks of chalcocite Cu2S hexagonal crystal structure for 0.4 M concentration. Also the surface and electrical characteristics were investigated using Field Emission Scanning Electron Microscopy (FESEM) and current source device, respectively. The surface study for the CuS thin films showed nanorods to be established for 0.2 M concentration and mix of nanorods and nanoplates for 0.4 M concentration. The electrical study showed ohmic behavior and low resistivity for these films. Hall Effect was measured for these thin films, it showed that all samples of CuS are p- type thin films and ensured that the resistivity for thin films of 0.2 M concentration was lower than that of 0.4 M concentration; and for the two concentrations CuS thin film deposited on ITO had the lowest resistivity. This leads to the result that the conductivity was high for CuS thin film deposited on ITO substrate, and the conductivity of the three thin films of 0.2 M concentration was higher than that of 0.4 M concentration.

  15. CuS p-type thin film characterization deposited on Ti, ITO and glass substrates using spray pyrolysis deposition (SPD) for light emitting diode (LED) application

    Energy Technology Data Exchange (ETDEWEB)

    Sabah, Fayroz A., E-mail: fayroz-arif@yahoo.com [Institue of Nano-Optoelectronics Research and Technology (INOR), School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Department of Electrical Engineering, College of Engineering, Al-Mustansiriya University, Baghdad (Iraq); Ahmed, Naser M., E-mail: naser@usm.my; Hassan, Z., E-mail: zai@usm.my; Azzez, Shrook A. [Institue of Nano-Optoelectronics Research and Technology (INOR), School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Rasheed, Hiba S., E-mail: hibasaad1980@yahoo.com [Institue of Nano-Optoelectronics Research and Technology (INOR), School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Department of Physics, College of Education, Al-Mustansiriya University, Baghdad (Iraq); Al-Hazim, Nabeel Z., E-mail: nabeelnano333@gmail.com [Institue of Nano-Optoelectronics Research and Technology (INOR), School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Ministry of Education, the General Directorate for Educational Anbar (Iraq)

    2016-07-06

    The copper sulphide (CuS) thin films were grown with good adhesion by spray pyrolysis deposition (SPD) on Ti, ITO and glass substrates at 200 °C. The distance between nozzle and substrate is 30 cm. The composition was prepared by mixing copper chloride CuCl{sub 2}.2H{sub 2}O as a source of Cu{sup 2+} and sodium thiosulfate Na{sub 2}S{sub 2}O{sub 3}.5H{sub 2}O as a source of and S{sup 2−}. Two concentrations (0.2 and 0.4 M) were used for each CuCl{sub 2} and Na{sub 2}S{sub 2}O{sub 3} to be prepared and then sprayed (20 ml). The process was started by spraying the solution for 3 seconds and after 10 seconds the cycle was repeated until the solution was sprayed completely on the hot substrates. The structural characteristics were studied using X-ray diffraction; they showed covellite CuS hexagonal crystal structure for 0.2 M concentration, and covellite CuS hexagonal crystal structure with two small peaks of chalcocite Cu{sub 2}S hexagonal crystal structure for 0.4 M concentration. Also the surface and electrical characteristics were investigated using Field Emission Scanning Electron Microscopy (FESEM) and current source device, respectively. The surface study for the CuS thin films showed nanorods to be established for 0.2 M concentration and mix of nanorods and nanoplates for 0.4 M concentration. The electrical study showed ohmic behavior and low resistivity for these films. Hall Effect was measured for these thin films, it showed that all samples of CuS are p- type thin films and ensured that the resistivity for thin films of 0.2 M concentration was lower than that of 0.4 M concentration; and for the two concentrations CuS thin film deposited on ITO had the lowest resistivity. This leads to the result that the conductivity was high for CuS thin film deposited on ITO substrate, and the conductivity of the three thin films of 0.2 M concentration was higher than that of 0.4 M concentration.

  16. Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning.

    Science.gov (United States)

    Zhang, H D; Yu, M; Zhang, J C; Sheng, C H; Yan, X; Han, W P; Liu, Y C; Chen, S; Shen, G Z; Long, Y Z

    2015-06-21

    La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

  17. Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning

    Science.gov (United States)

    Zhang, H. D.; Yu, M.; Zhang, J. C.; Sheng, C. H.; Yan, X.; Han, W. P.; Liu, Y. C.; Chen, S.; Shen, G. Z.; Long, Y. Z.

    2015-06-01

    La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

  18. Very low surface recombination velocity on p-type c-Si by high-rate plasma-deposited aluminum oxide

    Science.gov (United States)

    Saint-Cast, Pierre; Kania, Daniel; Hofmann, Marc; Benick, Jan; Rentsch, Jochen; Preu, Ralf

    2009-10-01

    Aluminum oxide layers can provide excellent passivation for lowly and highly doped p-type silicon surfaces. Fixed negative charges induce an accumulation layer at the p-type silicon interface, resulting in very effective field-effect passivation. This paper presents highly negatively charged (Qox=-2.1×1012 cm-2) aluminum oxide layers produced using an inline plasma-enhanced chemical vapor deposition system, leading to very low effective recombination velocities (˜10 cm s-1) on low-resistivity p-type substrates. A minimum static deposition rate (100 nm min-1) at least one order of magnitude higher than atomic layer deposition was achieved on a large carrier surfaces (˜1 m2) without significantly reducing the resultant passivation quality.

  19. Design of ``push-pull'' p-type quinoid-based organic dyes with near-IR absorption: A density function theory study

    Science.gov (United States)

    Yang, Zhenqing; Li, Juan; Liu, Yun; Zhang, Wansong

    2017-04-01

    Based on an experimentally synthesized p-type dye QT-1, we screened and designed a series of quinoid-based "push-pull" dyes SPL401 - SPL407 by modifying the π-conjugated linker for ptype dye-sensitized solar cells (p-type DSSC). Further, we systematically calculated their electronic and optical properties by using the density functional theory (DFT) and the time-dependent DFT (TDDFT). The results indicate that compared to QT-1, SPL406 and SPL407, which have not only smaller energy gaps, higher oscillator strength f increased by 70% and 80%, and 141 nm and 110 nm redshifts, respectively, but also a broader absorption spectrum covering the entire visible range to the near-IR region of 1200 nm, may be the most promising candidates among SPL401 - SPL407 for p-type organic sensitizers.

  20. Impact of common metallurgical impurities on ms-Si solar cell efficiency. P-type versus n-type doped ingots

    Energy Technology Data Exchange (ETDEWEB)

    Geerligs, L.J.; Manshanden, P. [ECN Solar Energy, Petten (Netherlands); Solheim, I.; Ovrelid, E.J.; Waernes, A.N. [Sintef materials technology, Trondheim (Norway)

    2006-09-15

    Silicon solar cells based on n-type silicon wafers are less sensitive to carrier lifetime degradation due to several common metal impurities than p-base cells. The theoretical and experimental indications for this have recently received considerable attention. This paper compares p-type and n-type cells purposely contaminated with relatively high levels of impurities, processed by industrial techniques. The impurities considered are Al, Ti, and Fe, which are the dominant impurities in metallurgical silicon and natural quartz. The work also preliminary addresses the question whether the optimal wafer resistivity is the same for n-type as for p-type base mc-Si cells.

  1. All-vapor processing of P-type tellurium-containing II-VI semiconductor and ohmic contacts thereof

    Energy Technology Data Exchange (ETDEWEB)

    McCandless, Brian E.

    2000-03-01

    An all dry method for producing solar cells is provided comprising first heat-annealing a II-VI semiconductor; enhancing the conductivity and grain size of the annealed layer; modifying the surface and depositing a tellurium layer onto the enhanced layer; and then depositing copper onto the tellurium layer so as to produce a copper tellurium compound on the layer.

  2. The origin of the ∼274 cm{sup −1} additional Raman mode induced by the incorporation of N dopants and a feasible route to achieve p-type ZnO:N thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ping [Key Laborat of Optoelectronic Functional Materials, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); Kong, Chunyang, E-mail: kchy@163.com [Key Laborat of Optoelectronic Functional Materials, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); Li, Wanjun, E-mail: liwj13@163.com [Key Laborat of Optoelectronic Functional Materials, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); College of Physics, Chongqing University, Chongqing 401331 (China); Qin, Guoping [Key Laborat of Optoelectronic Functional Materials, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); College of Physics, Chongqing University, Chongqing 401331 (China); Xu, Qing; Zhang, Hong [Key Laborat of Optoelectronic Functional Materials, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); Ruan, Haibo [Research Center for Materials Interdisciplinary Sciences, Chongqing University of Arts and Sciences, Chongqing 402160 (China); Cui, Yuting [Key Laborat of Optoelectronic Functional Materials, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); Fang, Liang [College of Physics, Chongqing University, Chongqing 401331 (China)

    2015-02-01

    Highlights: • ZnO:N films were grown on quartz substrates by RF magnetron sputtering technique. • ZnO:N thin films exhibit anomalous variation of ∼274 cm{sup −1} Raman mode. • The origin of the ∼274 cm{sup −1} mode induced by N dopants is Zn{sub i}-related defects. • Choosing appropriate N{sub 2} flow rate and annealing are the key to achieve p-type ZnO:N. - Abstract: Nitrogen doped ZnO films (ZnO:N) were deposited on quartz glass substrates by radio-frequency magnetron sputtering technique with various N{sub 2} flow rate mixed with Ar. Raman measurements indicate that the intensity of ∼274 cm{sup −1} mode of ZnO:N films exhibits an anomalous variation, which neither depends on N{sub 2} flow rate nor on N{sub O} acceptor content based on X-ray photoelectron spectroscopy (XPS) analysis. Combined with defect formation energy calculations, it is demonstrated that the ∼274 cm{sup −1} mode is attributed to Zn{sub i} defects which can be increased by the incorporation of N{sub O} acceptors, but suppressed by the presence of (N{sub 2}){sub O} double donors. XPS and optical absorption spectra suggest that ZnO:N film prepared under specific N{sub 2} flow rate (Ar:N{sub 2} = 3:1), has high concentration of acceptor N{sub O} with shallow states and the absence of shallow donor (N{sub 2}){sub O} defects, could be most likely to achieve p-type conductivity. But, at the same time, such specific ZnO:N film is the presence of shallow donor Zn{sub i} defects bonded with N{sub O} acceptors. Performing density functional calculations in conjunction with the climbing image nudged elastic band method shows that Zn{sub i} could be dissociated from Zn{sub i}–N{sub O} complexes by post-annealing treatment and N{sub O} acceptors would be activated to p-type ZnO:N. This is confirmed by our further Hall investigation, indicating that p-type ZnO:N can be achieved by choosing appropriate post-annealing treatment.

  3. Effect of viscosity of silver nanoparticle suspension on conductive line patterned by electrohydrodynamic jet printing

    Science.gov (United States)

    Exarhos, G. J.; Windisch, C. F., Jr.; Ferris, K. F.; Owings, R. R.

    2007-10-01

    High quality doped zinc oxide and mixed transition metal spinel oxide films have been deposited by means of sputter deposition from metal and metal oxide targets, and by spin casting from aqueous or alcoholic precursor solutions. Deposition conditions and post-deposition processing are found to alter cation oxidation states and their distributions in both oxide materials resulting in marked changes to both optical transmission and electrical response. For ZnO, partial reduction of the neat or doped material by hydrogen treatment of the heated film or by electrochemical processing renders the oxide n-type conducting. Continued reduction was found to diminish conductivity. In contrast, oxidation of the infrared transparent p-type spinel conductors typified by NiCo2O4 was found to increase conductivity. The disparate behavior of these two materials is caused, in part, by the sign of the charge carrier and by the existence of two different charge transport mechanisms that are identified as free carrier conduction and polaron hopping. While much work has been reported concerning structure/property relationships in the free carrier conducting oxides, there is a significantly smaller body of information on transparent polaron conductors. In this paper, we identify key parameters that promote conductivity in mixed metal spinel oxides and compare their behavior with that of the free carrier TCO’s.

  4. Enhancement of the thermoelectric performance of p-type layered oxide Ca3Co4O9+ through heavy doping and metallic nanoinclusions

    DEFF Research Database (Denmark)

    Van Nong, Ngo; Pryds, Nini; Linderoth, Søren

    2011-01-01

    An effective way to improve the thermoelectric performance (ZT) of layered structured oxide materials by carefully choosing heavy ion doping and introducing metallic nanoinclusions is proposed. A p-type oxide material with remarkable highly improved ZT is successfully fabricated using this approach...

  5. p-Type Semiconducting Nickel Oxide as an Efficiency-Enhancing Anode Interfacial Layer in Polymer Bulk-Heterojunction Solar Cells

    National Research Council Canada - National Science Library

    Michael D. Irwin; D. Bruce Buchholz; Alexander W. Hains; Robert P. H. Chang; Tobin J. Marks

    2008-01-01

    To minimize interfacial power losses, thin (5-80 nm) layers of NiO, a p-type oxide semiconductor, are inserted between the active organic layer, poly(3-hexylthiophene) (P3HT) + [6,6]-phenyl-C₆₁...

  6. Cellular function and pathological role of ATP13A2 and related P-type transport ATPases in Parkinson's disease and other neurological disorders.

    Science.gov (United States)

    van Veen, Sarah; Sørensen, Danny M; Holemans, Tine; Holen, Henrik W; Palmgren, Michael G; Vangheluwe, Peter

    2014-01-01

    Mutations in ATP13A2 lead to Kufor-Rakeb syndrome, a parkinsonism with dementia. ATP13A2 belongs to the P-type transport ATPases, a large family of primary active transporters that exert vital cellular functions. However, the cellular function and transported substrate of ATP13A2 remain unknown. To discuss the role of ATP13A2 in neurodegeneration, we first provide a short description of the architecture and transport mechanism of P-type transport ATPases. Then, we briefly highlight key P-type ATPases involved in neuronal disorders such as the copper transporters ATP7A (Menkes disease), ATP7B (Wilson disease), the Na(+)/K(+)-ATPases ATP1A2 (familial hemiplegic migraine) and ATP1A3 (rapid-onset dystonia parkinsonism). Finally, we review the recent literature of ATP13A2 and discuss ATP13A2's putative cellular function in the light of what is known concerning the functions of other, better-studied P-type ATPases. We critically review the available data concerning the role of ATP13A2 in heavy metal transport and propose a possible alternative hypothesis that ATP13A2 might be a flippase. As a flippase, ATP13A2 may transport an organic molecule, such as a lipid or a peptide, from one membrane leaflet to the other. A flippase might control local lipid dynamics during vesicle formation and membrane fusion events.

  7. Cellular function and pathological role of ATP13A2 and related P-type transport ATPases in Parkinson's disease and other neurological disorders

    DEFF Research Database (Denmark)

    van Veen, Sarah; Sørensen, Danny M.; Holemans, Tine

    2014-01-01

    Mutations in ATP13A2 lead to Kufor-Rakeb syndrome, a parkinsonism with dementia. ATP13A2 belongs to the P-type transport ATPases, a large family of primary active transporters that exert vital cellular functions. However, the cellular function and transported substrate of ATP13A2 remain unknown. ...

  8. Fabrication of p-Type ZnO:N Films by Oxidizing Zn3N2 Films in Oxygen Plasma at Low Temperature

    Directory of Open Access Journals (Sweden)

    Yuping Jin

    2017-02-01

    Full Text Available The oxygen vacancy (VO is known as the main compensation center in p-type ZnO, which leads to the difficulty of fabricating high-quality p-type ZnO. To reduce the oxygen vacancies, we oxidized Zn3N2 films in oxygen plasma and successfully prepared p-type ZnO:N films at temperatures ranging from room temperature to 300 °C. The films were characterized by X-ray diffraction (XRD, non-Rutherford backscattering (non-RBS spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectrum, and Hall Effect. The results show that the nitrogen atoms successfully substitute the oxygen sites in the ZnO:N films. The film prepared at room temperature exhibits the highest hole concentration of 6.22 × 1018 cm−3, and the lowest resistivity of 39.47 Ω∙cm. In all ZnO:N films, the VO defects are reduced significantly. At 200 °C, the film holds the lowest value of VO defects and the strongest UV emission. These results imply that oxygen plasma is very efficient in reducing VO defects in p-type ZnO:N films, and could greatly reduce the reaction temperature. This method is significant for the development of ZnO-based optoelectronic devices.

  9. Cellular function and pathological role of ATP13A2 and related P-type transport ATPases in Parkinson’s disease and other neurological disorders

    Directory of Open Access Journals (Sweden)

    Sarah evan Veen

    2014-05-01

    Full Text Available Mutations in ATP13A2 lead to Kufor-Rakeb syndrome, a parkinsonism with dementia. ATP13A2 belongs to the P-type transport ATPases, a large family of primary active transporters that exert vital cellular functions. However, the cellular function and transported substrate of ATP13A2 remain unknown. To discuss the role of ATP13A2 in neurodegeneration, we first provide a short description of the architecture and transport mechanism of P-type transport ATPases. Then, we briefly highlight key P-type ATPases involved in neuronal disorders such as the copper transporters ATP7A (Menkes disease, ATP7B (Wilson disease, the Na+/K+-ATPases ATP1A2 (familial hemiplegic migraine and ATP1A3 (rapid-onset dystonia parkinsonism. Finally, we review the recent literature of ATP13A2 and discuss ATP13A2’s putative cellular function in the light of what is known concerning the functions of other, better-studied P-type ATPases. We critically review the available data concerning the role of ATP13A2 in heavy metal transport and propose a possible alternative hypothesis that ATP13A2 might be a flippase. As a flippase, ATP13A2 may transport an organic molecule, such as a lipid or a peptide, from one membrane leaflet to the other. A flippase might control local lipid dynamics during vesicle formation and membrane fusion events.

  10. Sensitive optical bio-sensing of p-type WSe2 hybridized with fluorescent dye attached DNA by doping and de-doping effects

    Science.gov (United States)

    Han, Kyu Hyun; Kim, Jun Young; Jo, Seong Gi; Seo, Changwon; Kim, Jeongyong; Joo, Jinsoo

    2017-10-01

    Layered transition metal dichalcogenides, such as MoS2, WSe2 and WS2, are exciting two-dimensional (2D) materials because they possess tunable optical and electrical properties that depend on the number of layers. In this study, the nanoscale photoluminescence (PL) characteristics of the p-type WSe2 monolayer, and WSe2 layers hybridized with the fluorescent dye Cy3 attached to probe-DNA (Cy3/p-DNA), have been investigated as a function of the concentration of Cy3/DNA by using high-resolution laser confocal microscopy. With increasing concentration of Cy3/p-DNA, the measured PL intensity decreases and its peak is red-shifted, suggesting that the WSe2 layer has been p-type doped with Cy3/p-DNA. Then, the PL intensity of the WSe2/Cy3/p-DNA hybrid system increases and the peak is blue-shifted through hybridization with relatively small amounts of target-DNA (t-DNA) (50–100 nM). This effect originates from charge and energy transfer from the Cy3/DNA to the WSe2. For t-DNA detection, our systems using p-type WSe2 have the merit in terms of the increase of PL intensity. The p-type WSe2 monolayers can be a promising nanoscale 2D material for sensitive optical bio-sensing based on the doping and de-doping responses to biomaterials.

  11. Eco-friendly p-type Cu2SnS3 thermoelectric material: crystal structure and transport properties

    Science.gov (United States)

    Shen, Yawei; Li, Chao; Huang, Rong; Tian, Ruoming; Ye, Yang; Pan, Lin; Koumoto, Kunihito; Zhang, Ruizhi; Wan, Chunlei; Wang, Yifeng

    2016-01-01

    As a new eco-friendly thermoelectric material, copper tin sulfide (Cu2SnS3) ceramics were experimentally studied by Zn-doping. Excellent electrical transport properties were obtained by virtue of 3-dimensionally conductive network for holes, which are less affected by the coexistence of cubic and tetragonal phases that formed upon Zn subsitition for Sn; a highest power factors ~0.84 mW m−1 K−2 at 723 K was achieved in the 20% doped sample. Moreover, an ultralow lattice thermal conductivity close to theoretical minimum was observed in these samples, which could be related to the disordering of atoms in the coexisting cubic and tetragonal phases and the interfaces. Thanks to the phonon-glass-electron-crystal features, a maximum ZT ~ 0.58 was obtained at 723 K, which stands among the tops for sulfide thermoelectrics at the same temperature. PMID:27666524

  12. Employing PEDOT as the p-Type Charge Collection Layer in Regular Organic-Inorganic Perovskite Solar Cells.

    Science.gov (United States)

    Liu, Jiewei; Pathak, Sandeep; Stergiopoulos, Thomas; Leijtens, Tomas; Wojciechowski, Konrad; Schumann, Stefan; Kausch-Busies, Nina; Snaith, Henry J

    2015-05-07

    Organic-inorganic halide perovskite solar cells have recently emerged as high-performance photovoltaic devices with low cost, promising for affordable large-scale energy production, with laboratory cells already exceeding 20% power conversion efficiency (PCE). To date, a relatively expensive organic hole-conducting molecule with low conductivity, namely spiro-OMeTAD (2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl-amine) 9,9'- spirobifluorene), is employed widely to achieve highly efficient perovskite solar cells. Here, we report that by replacing spiro-OMeTAD with much cheaper and highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) we can achieve PCE of up to 14.5%, with PEDOT cast from a toluene based ink. However, the stabilized power output of the PEDOT-based devices is only 6.6%, in comparison to 9.4% for the spiro-OMeTAD-based cells. We deduce that accelerated recombination is the cause for this lower stabilized power output and postulate that reduced levels of p-doping are required to match the stabilized performance of Spiro-OMeTAD. The entirely of the materials employed in the perovskite solar cell are now available at commodity scale and extremely inexpensive.

  13. Poole-Frenkel effect on electrical characterization of Al-doped ZnO films deposited on p-type GaN

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bohr-Ran [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Liao, Chung-Chi [Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Ke, Wen-Cheng, E-mail: wcke@saturn.yzu.edu.tw; Chang, Yuan-Ching; Huang, Hao-Ping [Department of Mechanical Engineering, Yuan Ze University, Chung-Li 320, Taiwan (China); Chen, Nai-Chuan [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China)

    2014-03-21

    This paper presents the electrical properties of Al-doped ZnO (AZO) films directly grown on two types of p-type GaN thin films. The low-pressure p-GaN thin films (LP-p-GaN) exhibited structural properties of high-density edge-type threading dislocations (TDs) and compensated defects (i.e., nitrogen vacancy). Compared with high-pressure p-GaN thin films (HP-p-GaN), X-ray photoemission spectroscopy of Ga 3d core levels indicated that the surface Fermi-level shifted toward the higher binding-energy side by approximately 0.7 eV. The high-density edge-type TDs and compensated defects enabled surface Fermi-level shifting above the intrinsic Fermi-level, causing the surface of LP-p-GaN thin films to invert to n-type semiconductor. A highly nonlinear increase in leakage current regarding reverse-bias voltage was observed for AZO/LP-p-GaN. The theoretical fits for the reverse-bias voltage region indicated that the field-assisted thermal ionization of carriers from defect associated traps, which is known as the Poole-Frenkel effect, dominated the I-V behavior of AZO/LP-p-GaN. The fitting result estimated the trap energy level at 0.62 eV below the conduction band edge. In addition, the optical band gap increased from 3.50 eV for as-deposited AZO films to 3.62 eV for 300 °C annealed AZO films because of the increased carrier concentration. The increasing Fermi-level of the 300 °C annealed AZO films enabled the carrier transport to move across the interface into the LP-p-GaN thin films without any thermal activated energy. Thus, the Ohmic behavior of AZO contact can be achieved directly on the low-pressure p-GaN films at room temperature.

  14. Thermal conductivity of silicon nanowires embedded on thermoelectric platforms

    Science.gov (United States)

    Choi, JinYong; Cho, Kyoungah; Yoon, Dae Sung; Kim, Sangsig

    2016-10-01

    In this study, we propose a simple method for obtaining the thermal conductivity of silicon nanowires (SiNWs) embedded on a thermoelectric platform. The approximation of the heat flux in SiNWs with temperature differences enables the determination of thermal conductivity. Using this method, the thermal conductivities of our n- and p-type SiNWs are found to be 18.06  ±  0.12 and 20.29  ±  0.77 W m-1 · K-1, respectively. The atomic weight of arsenic ions in the n-type SiNWs is responsible for a lower thermal conductivity than that of boron ions in the p-type SiNWs. Our results demonstrate that this simple method is capable of measuring the thermal conductivity of thermoelectric nanomaterials embedded on thermoelectric devices.

  15. ZnO based transparent conductive oxide films with controlled type of conduction

    Energy Technology Data Exchange (ETDEWEB)

    Zaharescu, M., E-mail: mzaharescu@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Mihaiu, S., E-mail: smihaiu@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Toader, A. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Atkinson, I., E-mail: irinaatkinson@yahoo.com [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Calderon-Moreno, J.; Anastasescu, M.; Nicolescu, M.; Duta, M.; Gartner, M. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Vojisavljevic, K.; Malic, B. [Institute Jožef Stefan, Ljubljana (Slovenia); Ivanov, V.A.; Zaretskaya, E.P. [State Scientific and Production Association “Scientific-Practical Materials Research Center of the National Academy of Science Belarus, P. Brovska str.19, 220072, Minsk (Belarus)

    2014-11-28

    The transparent conductive oxide films with controlled type of conduction are of great importance and their preparation is intensively studied. In our work, the preparation of such films based on doped ZnO was realized in order to achieve controlled type of conduction and high concentration of the charge carriers. Sol–gel method was used for films preparation and several dopants were tested (Sn, Li, Ni). Multilayer deposition was performed on several substrates: SiO{sub 2}/Si wafers, silica-soda-lime and/or silica glasses. The structural and morphological characterization of the obtained films were done by scanning electron microscopy, X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy and atomic force microscopy respectively, while spectroscopic ellipsometry and transmittance measurements were done for determination of optical properties. The selected samples with the best structural, morphological and optical properties were subjected to electrical measurement (Hall and Seebeck effect). In all studied cases, samples with good adherence and homogeneous morphology as well as monophasic wurtzite type structure were obtained. The optical constants (refractive index and extinction coefficient) were calculated from spectroscopic ellipsometry data using Cauchy model. Films with n- or p-type conduction were obtained depending on the composition, number of deposition and thermal treatment temperature. - Highlights: • Transparent conductive ZnO based thin films were prepared by the sol–gel method. • Controlled type of conduction is obtained in (Sn, Li) doped and Li-Ni co-doped ZnO films. • Hall and Seebeck measurements proved the p-type conductivity for Li-Ni co-doped ZnO films. • The p-type conductivity was maintained even after 4-months of storage. • Influence of dopant- and substrate-type on the ZnO films properties was established.

  16. Photoelectron yield spectroscopy and inverse photoemission spectroscopy evaluations of p-type amorphous silicon carbide films prepared using liquid materials

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Tatsuya, E-mail: mtatsuya@jaist.ac.jp, E-mail: mtakashi@jaist.ac.jp [Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Masuda, Takashi, E-mail: mtatsuya@jaist.ac.jp, E-mail: mtakashi@jaist.ac.jp; Inoue, Satoshi; Shimoda, Tatsuya [Green Device Research Center, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1211 (Japan); Yano, Hiroshi; Iwamuro, Noriyuki [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennoudai, Tsukuba, Ibaraki 305-8573 (Japan)

    2016-05-15

    Phosphorus-doped amorphous silicon carbide films were prepared using a polymeric precursor solution. Unlike conventional polymeric precursors, this polymer requires neither catalysts nor oxidation for its synthesis and cross-linkage, providing semiconducting properties in the films. The valence and conduction states of resultant films were determined directly through the combination of inverse photoemission spectroscopy and photoelectron yield spectroscopy. The incorporated carbon widened energy gap and optical gap comparably in the films with lower carbon concentrations. In contrast, a large deviation between the energy gap and the optical gap was observed at higher carbon contents because of exponential widening of the band tail.

  17. 7 CFR 97.157 - Professional conduct.

    Science.gov (United States)

    2010-01-01

    ... Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) COMMODITY LABORATORY TESTING PROGRAMS... appearing before the Office shall conform to the standards of ethical and professional conduct,...

  18. Low-Programmable-Voltage Nonvolatile Memory Devices Based on Omega-shaped Gate Organic Ferroelectric P(VDF-TrFE) Field Effect Transistors Using p-type Silicon Nanowire Channels

    Institute of Scientific and Technical Information of China (English)

    Ngoc Huynh Van; Jae-Hyun Lee; Dongmok Whang; Dae Joon Kang

    2015-01-01

    A facile approach was demonstrated for fabricating high-performance nonvolatile memory devices based on ferroelectric-gate field effect transistors using a p-type Si nanowire coated with omega-shaped gate organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)). We overcame the interfacial layer problem by incorporating P(VDF-TrFE) as a ferroelectric gate using a low-temperature fabrication process. Our memory devices exhibited excellent memory characteristics with a low programming voltage of ±5 V, a large modulation in channel conductance between ON and OFF states exceeding 105, a long retention time greater than 3 9 104 s, and a high endurance of over 105 programming cycles while maintaining an ION/IOFF ratio higher than 102.

  19. Versatile and Tunable Transparent Conducting Electrodes Based on Doped Graphene

    KAUST Repository

    Mansour, Ahmed E.

    2016-11-25

    The continued growth of the optoelectronics industry and the emergence of wearable and flexible electronics will continue to place an ever increasing pressure on replacing ITO, the most widely used transparent conducting electrode (TCE). Among the various candidates, graphene shows the highest optical transmittance in addition to promising electrical transport properties. The currently available large-scale synthesis routes of graphene result in polycrystalline samples rife with grain boundaries and other defects which limit its transport properties. Chemical doping of graphene is a viable route towards increasing its conductivity and tuning its work function. However, dopants are typically present at the surface of the graphene sheet, making them highly susceptible to degradation in environmental conditions. Few-layers graphene (FLG) is a more resilient form of graphene exhibiting higher conductivity and performance stability under stretching and bending as contrasted to single-layer graphene. In addition FLG presents the advantage of being amenable bulk doping by intercalation. Herein, we explore non-covalent doping routes of CVD FLG, such as surface doping, intercalation and combination thereof, through in-depth and systematic characterization of the electrical transport properties and energy levels shifts. The intercalation of FLG with Br2 and FeCl3 is demonstrated, showing the highest improvements of the figure of merit of TCEs of any doping scheme, which results from up to a five-fold increase in conductivity while maintaining the transmittance within 3% of that for the pristine value. Importantly the intercalation yields TCEs that are air-stable, due to encapsulation of the intercalant in the bulk of FLG. Surface doping with novel solution-processed metal-organic molecular species (n- and p-type) is demonstrated with an unprecedented range of work function modulation, resulting from electron transfer and the formation of molecular surface dipoles. However

  20. Adjustable hydrazine modulation of single-wall carbon nanotube network field effect transistors from p-type to n-type

    Science.gov (United States)

    Dai, Ruixuan; Xie, Dan; Xu, Jianlong; Sun, Yilin; Sun, MengXing; Zhang, Cheng; Li, Xian

    2016-11-01

    Single-wall carbon nanotube (SWCNT) network field effect transistors (FETs), which show decent p-type electronic properties, have been fabricated. The use of hydrazine as an aqueous solution and a strong n-type dopant for the SWCNTs is demonstrated in this paper. The electrical properties are obviously tuned by hydrazine treatment at different concentrations on the surface of the SWCNT network FETs. The transport behavior of SWCNTs can be modulated from p-type to n-type, demonstrating the controllable and adjustable doping effect of hydrazine. With a higher concentration of hydrazine, more electrons can be transferred from the hydrazine molecules to the SWCNT network films, thus resulting in a change of threshold voltage, carrier mobility and on-current. By cleaning the device, the hydrazine doping effects vanish, which indicates that the doping effects of hydrazine are reversible. Through x-ray photoelectron spectroscopy (XPS) characterization, the doping effects of hydrazine have also been studied.