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Sample records for total film growth

  1. Ion beam assisted film growth

    CERN Document Server

    Itoh, T

    2012-01-01

    This volume provides up to date information on the experimental, theoretical and technological aspects of film growth assisted by ion beams.Ion beam assisted film growth is one of the most effective techniques in aiding the growth of high-quality thin solid films in a controlled way. Moreover, ion beams play a dominant role in the reduction of the growth temperature of thin films of high melting point materials. In this way, ion beams make a considerable and complex contribution to film growth. The volume will be essential reading for scientists, engineers and students working in thi

  2. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  3. Total Recall: Using Film to Enhance Learning

    Science.gov (United States)

    Clayton, Douglas N.

    2012-01-01

    Several scholars (e.g. Bumpus, 2005; Champoux, 1999; Mayer, 2005) and practitioners (Gallos 2007; English & Steffy, 1995; Hackley, 2007) of workplace learning have put forward the claim that the use of film (and other forms of multimedia) enhances learning. If this is the case, particularly given the increasing pressure to do more with less,…

  4. Growth of anodic films on niobium

    International Nuclear Information System (INIS)

    Gomes, M.A.B.; Bulhoes, L.O.S.

    1988-01-01

    The analysis of the response of the galvanostatic growth of anodic films on niobium metal in aqueous solutions is shown. The first spark voltage showed a dependence upon value of current density that could be explained as the incorporation of anions into the film. (M.J.C.) [pt

  5. Growth of organic films on indoor surfaces

    DEFF Research Database (Denmark)

    Weschler, Charles J.; Nazaroff, W. W.

    2017-01-01

    predictions indicate that film growth would primarily be influenced by the gas-phase concentration of SVOCs with octanol-air partitioning (Koa) values in the approximate range 10≤log Koa≤13. Within the relevant range, SVOCs with lower values will equilibrate with the surface film more rapidly. Over time...

  6. Role of nucleation in nanodiamond film growth

    International Nuclear Information System (INIS)

    Lifshitz, Y.; Lee, C.H.; Wu, Y.; Zhang, W.J.; Bello, I.; Lee, S.T.

    2006-01-01

    Nanodiamond films were deposited using different microwave plasma chemical vapor deposition schemes following several nucleation pretreatment methods. The nucleation efficiency and the films structure were investigated using scanning and transmission electron microscopy and Raman spectroscopy. C 2 dimer growth (CH 4 and H 2 in 90% Ar) cannot nucleate diamond and works only on existing diamond surfaces. The methyl radical process (up to 20% CH 4 in H 2 ) allows some nucleation probability on appropriate substrates. Prolonged bias enhanced nucleation initiates both diamond nucleation and growth. C 2 dimer growth results in pure nanodiamond free of amorphous carbon, while prolonged bias enhanced nucleation forms an amorphous carbon/nanodiamond composite

  7. Reliability growth of thin film resistors contact

    Directory of Open Access Journals (Sweden)

    Lugin A. N.

    2010-10-01

    Full Text Available Necessity of resistive layer growth under the contact and in the contact zone of resistive element is shown in order to reduce peak values of current flow and power dissipation in the contact of thin film resistor, thereby to increase the resistor stability to parametric and catastrophic failures.

  8. Nonimaging light concentration using total internal reflection films.

    Science.gov (United States)

    Ouellette, G; Waltham, C E; Drees, R M; Poon, A; Schubank, R; Whitehead, L A

    1992-05-01

    We present a method of fabricating nonimaging light concentrators from total internal reflection film. A prototype has been made and tested and found to operate in agreement with predictions of ray-tracing codes. The performance of the prototype is comparable with that of concentrators made from specular reflecting materials.

  9. Thin film characterization by total reflection x-ray fluorescence

    International Nuclear Information System (INIS)

    Danel, Adrien; Nolot, Emmanuel; Veillerot, Marc; Olivier, Segolene; Decorps, Tifenn; Calvo-Munoz, Maria-Luisa; Hartmann, Jean-Michel; Lhostis, Sandrine; Kohno, Hiroshi; Yamagami, Motoyuki; Geoffroy, Charles

    2008-01-01

    Sensitive and accurate characterization of films thinner than a few nm used in nanoelectronics represents a challenge for many conventional production metrology tools. With capabilities in the 10 10 at/cm 2 , methods usually dedicated to contamination analysis appear promising, especially Total-reflection X-Ray Fluorescence (TXRF). This study shows that under usual configuration for contamination analysis, with incident angle smaller than the critical angle of the substrate, TXRF signal saturation occurs very rapidly for dense films (below 0.5 nm for HfO 2 films on Si wafers using a 9.67 keV excitation at 0.5 deg.). Increasing the incident angle, the range of linear results can be extended, but on the other hand, the TXRF sensitivity is degraded because of a strong increase of the measurement dead time. On HfO 2 films grown on Si wafers, an incident angle of 0.32 deg. corresponding to a dead time of 95% was used to achieve linear analysis up to 2 nm. Composition analysis by TXRF, and especially the detection of minor elements into thin films, requires the use of a specific incident angle to optimize sensitivity. Although quantitative analyses might require specific calibration, this work shows on Co-based films that the ratio between minor elements (W, P, Mo) and Co taking into account their relative sensitivity factors is a good direct reading of the composition

  10. Thin-film growth and the shadow instability

    International Nuclear Information System (INIS)

    Karunasiri, R.P.U.; Bruinsma, R.; Rudnick, J.

    1989-01-01

    We propose a growth model for deposition of thin amorphous films by the sputtering technique. For small values of the diffusion constant, the film develops a self-similar mountain landscape. As the diffusion constant is increased a regime is reached where growth of compact flat films is possible up to a critical height. Further deposition leads to surface roughening

  11. Physical phenomena stipulating nucleus formation, growth and structure films

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, L N [AN SSSR, Novosibirsk. Inst. Fiziki Poluprovodnikov

    1975-03-01

    This review is concerned with the physical phenomena responsible for the nucleation, growth and structure of films. Emphasis is placed on the study of films of solid-metal systems, semiconductors (In, As, Cd, Se, CdS), and dielectrics. The following problems are discussed in the paper: general regularities of the thermodynamics and kinetics of film formation, methods of obtaining a solid film, the process of film formation, the rate of growth of individual grains. The critical film thickness and its measurement are also considered. The results of investigating the process of formation of mono- and polycrystalline films are discussed. It is concluded, on the basis of studies into the relaxation processes accompanying the growth of films, that an insight into these processes will permits improving film properties.

  12. Surface smoothening effects on growth of diamond films

    Science.gov (United States)

    Reshi, Bilal Ahmad; Kumar, Shyam; Kartha, Moses J.; Varma, Raghava

    2018-04-01

    We have carried out a detailed study of the growth dynamics of the diamond film during initial time on diamond substrates. The diamond films are deposited using Microwave Plasma Chemical Vapor Deposition (MPCVD) method for different times. Surface morphology and its correlation with the number of hours of growth of thin films was invested using atomic force microscopy (AFM). Diamond films have smooth interface with average roughness of 48.6873nm. The initial growth dynamics of the thin film is investigated. Interestingly, it is found that there is a decrease in the surface roughness of the film. Thus a smoothening effect is observed in the grown films. The film enters into the growth regime in the later times. Our results also find application in building diamond detector.

  13. Totally impermeable film (TIF reduces emissions in perennial crop fumigation

    Directory of Open Access Journals (Sweden)

    Suduan Gao

    2013-10-01

    Full Text Available Many perennial nursery fields and replanted orchards and vineyards in California are treated with preplant soil fumigants to control soilborne pests. In annual crops, such as strawberry, covering fumigated fields with totally impermeable film (TIF has shown promise in controlling emissions and improving fumigant distribution in soil. The objective of this research was to optimize the use of TIF for perennial crops via three field trials. TIF reduced peak emission flux and cumulative emissions by > 90% relative to polyethylene tarp during a 2-week covering period. After the TIF was cut, emissions were greatly reduced compared to when tarps were cut after 6 days. TIF maintained higher fumigant concentrations under tarp and in the soil than polyethylene film. The results indicate that TIF can increase fumigation efficiency for perennial crop growers.

  14. Growth of epitaxial thin films by pulsed laser ablation

    International Nuclear Information System (INIS)

    Lowndes, D.H.

    1992-01-01

    High-quality, high-temperature superconductor (HTSc) films can be grown by the pulsed laser ablation (PLA) process. This article provides a detailed introduction to the advantages and curent limitations of PLA for epitaxial film growth. Emphasis is placed on experimental methods and on exploitation of PLA to control epitaxial growth at either the unit cell or the atomic-layer level. Examples are taken from recent HTSc film growth. 33 figs, 127 refs

  15. Self-Limited Growth in Pentacene Thin Films.

    Science.gov (United States)

    Pachmajer, Stefan; Jones, Andrew O F; Truger, Magdalena; Röthel, Christian; Salzmann, Ingo; Werzer, Oliver; Resel, Roland

    2017-04-05

    Pentacene is one of the most studied organic semiconducting materials. While many aspects of the film formation have already been identified in very thin films, this study provides new insight into the transition from the metastable thin-film phase to bulk phase polymorphs. This study focuses on the growth behavior of pentacene within thin films as a function of film thickness ranging from 20 to 300 nm. By employing various X-ray diffraction methods, combined with supporting atomic force microscopy investigations, one crystalline orientation for the thin-film phase is observed, while three differently tilted bulk phase orientations are found. First, bulk phase crystallites grow with their 00L planes parallel to the substrate surface; second, however, crystallites tilted by 0.75° with respect to the substrate are found, which clearly dominate the former in ratio; third, a different bulk phase polymorph with crystallites tilted by 21° is found. The transition from the thin-film phase to the bulk phase is rationalized by the nucleation of the latter at crystal facets of the thin-film-phase crystallites. This leads to a self-limiting growth of the thin-film phase and explains the thickness-dependent phase behavior observed in pentacene thin films, showing that a large amount of material is present in the bulk phase much earlier during the film growth than previously thought.

  16. ZnO film deposition on Al film and effects of deposition temperature on ZnO film growth characteristics

    International Nuclear Information System (INIS)

    Yoon, Giwan; Yim, Munhyuk; Kim, Donghyun; Linh, Mai; Chai, Dongkyu

    2004-01-01

    The effects of the deposition temperature on the growth characteristics of the ZnO films were studied for film bulk acoustic wave resonator (FBAR) device applications. All films were deposited using a radio frequency magnetron sputtering technique. It was found that the growth characteristics of ZnO films have a strong dependence on the deposition temperature from 25 to 350 deg. C. ZnO films deposited below 200 deg. C exhibited reasonably good columnar grain structures with highly preferred c-axis orientation while those above 200 deg. C showed very poor columnar grain structures with mixed-axis orientation. This study seems very useful for future FBAR device applications

  17. Growth of anodic oxide films on oxygen-containing niobium

    Energy Technology Data Exchange (ETDEWEB)

    Habazaki, H. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)]. E-mail: habazaki@eng.hokudai.ac.jp; Ogasawara, T. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Konno, H. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Shimizu, K. [University Chemical Laboratory, Keio University, Yokohama 223-8522 (Japan); Asami, K. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Saito, K. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Nagata, S. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Skeldon, P. [Corrosion and Protection Centre, School of Materials, The University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom); Thompson, G.E. [Corrosion and Protection Centre, School of Materials, The University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)

    2005-09-20

    The present study is directed at understanding of the influence of oxygen in the metal on anodic film growth on niobium, using sputter-deposited niobium containing from about 0-52 at.% oxygen, with anodizing carried out at high efficiency in phosphoric acid electrolyte. The findings reveal amorphous anodic niobia films, with no significant effect of oxygen on the field strength, transport numbers, mobility of impurity species and capacitance. However, since niobium is partially oxidized due to presence of oxygen in the substrate, less charge is required to form the films, hence reducing the time to reach a particular film thickness and anodizing voltage. Further, the relative thickness of film material formed at the metal/film interface is increased by the incorporation of oxygen species into the films from the substrate, with an associated altered depth of incorporation of phosphorus species into the films.

  18. Correlating defect density with growth time in continuous graphene films.

    Science.gov (United States)

    Kang, Cheong; Jung, Da Hee; Nam, Ji Eun; Lee, Jin Seok

    2014-12-01

    We report that graphene flakes and films which were synthesized by copper-catalyzed atmospheric pressure chemical vapor deposition (APCVD) method using a mixture of Ar, H2, and CH4 gases. It was found that variations in the reaction parameters, such as reaction temperature, annealing time, and growth time, influenced the domain size of as-grown graphene. Besides, the reaction parameters influenced the number of layers, degree of defects and uniformity of the graphene films. The increase in growth temperature and annealing time tends to accelerate the graphene growth rate and increase the diffusion length, respectively, thereby increasing the average size of graphene domains. In addition, we confirmed that the number of pinholes reduced with increase in the growth time. Micro-Raman analysis of the as-grown graphene films confirmed that the continuous graphene monolayer film with low defects and high uniformity could be obtained with prolonged reaction time, under the appropriate annealing time and growth temperature.

  19. Epitaxial growth of fcc Ti films on Al(001) surfaces

    International Nuclear Information System (INIS)

    Saleh, A.A.; Shutthanandan, V.; Shivaparan, N.R.; Smith, R.J.; Tran, T.T.; Chambers, S.A.

    1997-01-01

    High-energy ion scattering (HEIS), x-ray photoelectron spectroscopy, and x-ray photoelectron diffraction (XPD) were used to study the growth of thin Ti films on Al(001) surfaces. The Al surface peak area in the backscattered ion spectrum of MeV He + ions, incident along the [00 bar 1] direction, was used to monitor the atomic structure of the Ti films during growth. An initial decrease in the area was observed indicating epitaxial film growth. This decrease continued up to a critical film thickness of about 5.5 ML, after which point the structure of the film changed. Titanium films 3, 5, and 9 ML thick were characterized using XPD in the same chamber. Both the HEIS and XPD results show that the Ti films grow with an fcc structure on Al(001). A tetragonal distortion of 2.4% in the fcc Ti film was measured using ions incident along the [10 bar 1] direction. Although there is a general similarity of fcc Ti growth on both Al(001) and Al(110), the submonolayer growth regime does show differences for the two surfaces. copyright 1997 The American Physical Society

  20. Measuring thin films using quantitative frustrated total internal reflection (FTIR)

    NARCIS (Netherlands)

    Shirota, Minori; van Limbeek, Michiel A.J.; Lohse, Detlef; Sun, Chao

    2017-01-01

    Abstract.: In the study of interactions between liquids and solids, an accurate measurement of the film thickness between the two media is essential to study the dynamics. As interferometry is restricted by the wavelength of the light source used, recent studies of thinner films have prompted the

  1. Surface preparation for the heteroepitactic growth of ceramic thin films

    International Nuclear Information System (INIS)

    Norton, M.G.; Summerfelt, S.R.; Carter, C.B.

    1990-01-01

    The morphology, composition, and crystallographic orientation of the substrate influence the nucleation and growth of deposited thin films. A method for the preparation of controlled, characteristic surfaces is reported. The surfaces are suitable for the heteroepitactic growth of thin films. When used in the formation of electron-transparent thin foils, the substrates can be used to investigate the very early stages of film growth using transmission electron microscopy. The substrate preparation involves the cleaning and subsequent annealing to generate a surface consisting of a series of steps. The step terraces are formed on the energetically stable surface, and controlled nucleation and growth of films at step edges is found. The substrate materials prepared using this technique include (001) MgO, (001) SrTiO 3 , and (001) LaAlO 3

  2. Simulated Thin-Film Growth and Imaging

    Science.gov (United States)

    Schillaci, Michael

    2001-06-01

    Thin-films have become the cornerstone of the electronics, telecommunications, and broadband markets. A list of potential products includes: computer boards and chips, satellites, cell phones, fuel cells, superconductors, flat panel displays, optical waveguides, building and automotive windows, food and beverage plastic containers, metal foils, pipe plating, vision ware, manufacturing equipment and turbine engines. For all of these reasons a basic understanding of the physical processes involved in both growing and imaging thin-films can provide a wonderful research project for advanced undergraduate and first-year graduate students. After producing rudimentary two- and three-dimensional thin-film models incorporating ballsitic deposition and nearest neighbor Coulomb-type interactions, the QM tunneling equations are used to produce simulated scanning tunneling microscope (SSTM) images of the films. A discussion of computational platforms, languages, and software packages that may be used to accomplish similar results is also given.

  3. Growth model of Au films on Ru(001)

    International Nuclear Information System (INIS)

    Canessa, E.; Calmetta, A.

    1992-06-01

    In an attempt to find generic features on the fractal growth of Au films deposited on Ru(001), a simple simulation model based on irreversible diffusion-limited aggregation (DLA) is discussed. Highly irregular two-dimensional dentritic islands of Au particles that gradually grow on a larger host lattice of Ru particles and have fractal dimension d f approx. 1.70 each, are generated via a multiple had-hoc version of the DLA algorithm for single aggregates. Annealing effects on the islands morphology are reproduced assuming different sticking probabilities at nearest-neighbour lattice sites of Au films on Ru(001). Using simulation data, islands growth are described in analogy to diffusion-limited, precipitate growth with soft impingement of precipities. This leads to analyse thin film island growth kinetics in such fractal systems and to predict a main peak in scattering intensity patterns due to interisland interference. (author). 12 refs, 4 figs

  4. Cadmium sulfide thin films growth by chemical bath deposition

    Science.gov (United States)

    Hariech, S.; Aida, M. S.; Bougdira, J.; Belmahi, M.; Medjahdi, G.; Genève, D.; Attaf, N.; Rinnert, H.

    2018-03-01

    Cadmium sulfide (CdS) thin films have been prepared by a simple technique such as chemical bath deposition (CBD). A set of samples CdS were deposited on glass substrates by varying the bath temperature from 55 to 75 °C at fixed deposition time (25 min) in order to investigate the effect of deposition temperature on CdS films physical properties. The determination of growth activation energy suggests that at low temperature CdS film growth is governed by the release of Cd2+ ions in the solution. The structural characterization indicated that the CdS films structure is cubic or hexagonal with preferential orientation along the direction (111) or (002), respectively. The optical characterization indicated that the films have a fairly high transparency, which varies between 55% and 80% in the visible range of the optical spectrum, the refractive index varies from 1.85 to 2.5 and the optical gap value of which can reach 2.2 eV. It can be suggested that these properties make these films perfectly suitable for their use as window film in thin films based solar cells.

  5. Domain growth kinetics in stratifying foam films

    Science.gov (United States)

    Zhang, Yiran; Sharma, Vivek

    2015-11-01

    Baking bread, brewing cappuccino, pouring beer, washing dishes, shaving, shampooing, whipping eggs and blowing bubbles all involve creation of aqueous foam films. Typical foam films consist of two surfactant-laden surfaces that are ~ 5 nm - 10 micron apart. Sandwiched between these interfacial layers is a fluid that drains primarily under the influence of viscous and interfacial forces, including disjoining pressure. Interestingly, a layered ordering of micelles inside the foam films (thickness characteristic scaling laws. Though several studies have focused on the expansion dynamics of isolated domains that exhibit a diffusion-like scaling, the change in expansion kinetics observed after domains contact with the Plateau border has not been reported and analyzed before.

  6. Growth of ultra-thin Ag films on Ni(111)

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Axel; Flege, Jan Ingo; Falta, Jens [Institute of Solid State Physics, University of Bremen, 28359 Bremen (Germany); Senanayake, Sanjaya [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Alamgir, Faisal [Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

    2009-07-01

    The physical and chemical properties of ultra-thin metal films on metallic substrates strongly depend on their morphology and the structure of the buried interface. Hence, detailed knowledge of the growth mechanisms is essential for the creation of new functional materials with novel characteristics. In this contribution, we present a comprehensive structural study of the growth and properties of epitaxial Ag films on Ni(111) by in-situ low energy electron microscopy (LEEM). For lower temperatures, the growth of the Ag film proceeds in a Stranski-Krastanov mode after completion of the wetting layer, while for higher temperatures layer-by-layer growth is observed. Quantitative information about the film structure were obtained by analyzing the intensity-voltage (I-V) dependence of the local electron reflectivity (IV-LEEM). The corresponding I(V) spectra showed intensity oscillations depending on local thickness of the Ag film due to the quantum size effect (QSE). Modeling of the I(V) spectra was performed both within the framework of a one-dimensional Kronig-Penney model and multiple scattering IV-LEED calculations. The results of both approaches concerning the variation of the layer spacings and interface characteristics for different temperatures and film thicknesses will be discussed.

  7. Growth and structure of Co/Au magnetic thin films

    International Nuclear Information System (INIS)

    Marsot, N.

    1999-01-01

    We have studied the growth and the crystallographic structure of magnetic ultra thin cobalt/gold films (Co/Au), in order to investigate the correlations between their magnetic and structural properties. Room temperature (R.T.) Co growth on Au (111) proceeds in three stages. Up to 2 Co monolayers (ML), a bilayer island growth mode is observed. Between 2 and 5 ML, coalescence of the islands occurs, covering the substrate surface and a Co/Au mixing is observed resulting from the de-construction of the Herringbone reconstruction. Finally, beyond 5 ML, the CoAu mixing is buried and the Co growth continues in a 3-D growth. Annealing studies at 600 K on this system show a smoothing effect of the Co film, and at the same time, segregation of Au atoms. The quality of the Co/Au interface (sharpness) is not enhanced by the annealing. The local order was studied by SEXAFS and the long range order by GIXRD showing that the Co film has a hexagonal close packed structure, with an easy magnetization axis perpendicular to the surface. From a local order point of view, the Co grows with an incoherent epitaxy and keeps its own bulk parameters. The GIXRD analysis shows a residual strain in the Co film of 4%. The difference observed between the local order analysis and the long range order results is explained in terms of the low dimensions of the diffracting domains. The evolution of film strains, as a function of the Co coverage, shows a marked deviation from the elastic strain theory. Modification of the strain field in the Co film as a function of the Au coverage is studied by GIXRD analysis. The Au growth study, at R.T., shows no evidence of a Au/Co mixing in the case of the Au/Co interface. The Au overlayer adopts a twinned face centred cubic structure on the rough Co film surface. (author)

  8. Liquid phase epitaxial growth of heterostructured hierarchical MOF thin films

    KAUST Repository

    Chernikova, Valeriya; Shekhah, Osama; Spanopoulos, Ioannis; Trikalitis, Pantelis N.; Eddaoudi, Mohamed

    2017-01-01

    Precise control of epitaxial growth of MOF-on-MOF thin films, for ordered hierarchical tbo-type structures is demonstrated. The heterostructured MOF thin film was fabricated by successful sequential deposition of layers from two different MOFs. The 2-periodic layers, edge-transitive 4,4-square lattices regarded as supermolecular building layers, were commendably cross-linked using a combination of inorganic/organic and organic pillars.

  9. Liquid phase epitaxial growth of heterostructured hierarchical MOF thin films

    KAUST Repository

    Chernikova, Valeriya

    2017-05-10

    Precise control of epitaxial growth of MOF-on-MOF thin films, for ordered hierarchical tbo-type structures is demonstrated. The heterostructured MOF thin film was fabricated by successful sequential deposition of layers from two different MOFs. The 2-periodic layers, edge-transitive 4,4-square lattices regarded as supermolecular building layers, were commendably cross-linked using a combination of inorganic/organic and organic pillars.

  10. Thin films growth parameters in MAPLE; application to fibrinogen

    International Nuclear Information System (INIS)

    Jelinek, M; Cristescu, R; Kocourek, T; Vorlicek, V; Remsa, J; Stamatin, L; Mihaiescu, D; Stamatin, I; Mihailescu, I N; Chrisey, D B

    2007-01-01

    Increasingly requirements on the thin film quality of functionalized materials are efficiently met by a novel laser processing technique - Matrix Assisted Pulsed Laser Evaporation (MAPLE). Examples of deposition conditions and main features characteristic to film growth rate of MAPLE-fabricated organic materials are summarized. MAPLE experimental results are compared with ones corresponding to the classical Pulsed Laser Deposition (PLD). In particular, the results of investigation of MAPLE-deposited fibrinogen blood protein thin films using a KrF* excimer laser and characterized by FTIR and Raman spectrometry are reported

  11. New phenomena in epitaxial growth: solid films on quasicrystalline substrates

    International Nuclear Information System (INIS)

    Fournee, V; Thiel, P A

    2005-01-01

    An overview is given of the research conducted in the field of solid film growth on quasiperiodic surfaces. An atomistic description of quasicrystalline surfaces is presented and discussed in relation to bulk structural models. The various systems for which thin film growth has been attempted so far are reviewed. Emphasis is placed on the nucleation mechanisms of the solid films, on their growth modes in relation to the nature of the deposited metals, on the possibility of intermixing or alloying at the interface and on the epitaxial relationships at the crystal-quasicrystal interfaces. We also describe situations where the deposited elements adopt a quasiperiodic structure, which opens up the possibility of extending our understanding of the relation between quasiperiodicity and the physical properties of such structurally and chemically complex solids. (topical review)

  12. Single crystalline metal films as substrates for graphene growth

    Energy Technology Data Exchange (ETDEWEB)

    Zeller, Patrick; Henss, Ann-Kathrin; Wintterlin, Joost [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany); Weinl, Michael; Schreck, Matthias [Institut fuer Physik, Universitaet Augsburg (Germany); Speck, Florian; Ostler, Markus [Lehrstuhl fuer Technische Physik, Universitaet Erlangen-Nuernberg, Erlangen (Germany); Institut fuer Physik, Technische Universitaet Chemnitz (Germany); Seyller, Thomas [Institut fuer Physik, Technische Universitaet Chemnitz (Germany)

    2017-11-15

    Single crystalline metal films deposited on YSZ-buffered Si(111) wafers were investigated with respect to their suitability as substrates for epitaxial graphene. Graphene was grown by CVD of ethylene on Ru(0001), Ir(111), and Ni(111) films in UHV. For analysis a variety of surface science methods were used. By an initial annealing step the surface quality of the films was strongly improved. The temperature treatments of the metal films caused a pattern of slip lines, formed by thermal stress in the films, which, however, did not affect the graphene quality and even prevented wrinkle formation. Graphene was successfully grown on all three types of metal films in a quality comparable to graphene grown on bulk single crystals of the same metals. In the case of the Ni(111) films the originally obtained domain structure of rotational graphene phases could be transformed into a single domain by annealing. This healing process is based on the control of the equilibrium between graphene and dissolved carbon in the film. For the system graphene/Ni(111) the metal, after graphene growth, could be removed from underneath the epitaxial graphene layer by a pure gas phase reaction, using the reaction of CO with Ni to give gaseous Ni(CO){sub 4}. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Energy consumption and total factor productivity growth in Iranian agriculture

    Directory of Open Access Journals (Sweden)

    Reza Moghaddasi

    2016-11-01

    Full Text Available In this study we investigated the relation between energy consumption and growth of total factor productivity (TFP of agriculture in Iran from 1974 to 2012 using Solow residual method. The results from estimated aggregate Cobb–Douglas production function showed that one percent change in the value of labor, capital and energy will lead to 4.07, 0.09 and 0.49 percent change in agriculture value added, respectively. Also in a long term, based on the Johansen cointegration test, there is a negative relation between TFP growth and energy consumption in Iranian agriculture which might be due to cheap and inefficient energy use in this sector. Gradual liberalization of energy price and use of so called green box support policies is recommended.

  14. Growth of Ge films by cluster beam deposition

    CERN Document Server

    Xu, J L; Feng, J Y

    2002-01-01

    Ge epitaxial layers with reasonable quality were grown on the Si(1 1 1) substrates by cluster beam deposition (CBD) process. The growth temperature plays a dominant role in the epitaxial growth of Ge films. The substrate temperature for epitaxial growth is about 500 deg. C, which is lower than the reported critical temperature of Ge epitaxial growth by MBE and CVD. A stress induced phase transition of Ge lattice from cubic to tetragonal is also observed in the CBD process, and the mechanism is discussed.

  15. Perovskite Oxide Thin Film Growth, Characterization, and Stability

    Science.gov (United States)

    Izumi, Andrew

    Studies into a class of materials known as complex oxides have evoked a great deal of interest due to their unique magnetic, ferroelectric, and superconducting properties. In particular, materials with the ABO3 perovskite structure have highly tunable properties because of the high stability of the structure, which allows for large scale doping and strain. This also allows for a large selection of A and B cations and valences, which can further modify the material's electronic structure. Additionally, deposition of these materials as thin films and superlattices through techniques such as pulsed laser deposition (PLD) results in novel properties due to the reduced dimensionality of the material. The novel properties of perovskite oxide heterostructures can be traced to a several sources, including chemical intermixing, strain and defect formation, and electronic reconstruction. The correlations between microstructure and physical properties must be investigated by examining the physical and electronic structure of perovskites in order to understand this class of materials. Some perovskites can undergo phase changes due to temperature, electrical fields, and magnetic fields. In this work we investigated Nd0.5Sr 0.5MnO3 (NSMO), which undergoes a first order magnetic and electronic transition at T=158K in bulk form. Above this temperature NSMO is a ferromagnetic metal, but transitions into an antiferromagnetic insulator as the temperature is decreased. This rapid transition has interesting potential in memory devices. However, when NSMO is deposited on (001)-oriented SrTiO 3 (STO) or (001)-oriented (LaAlO3)0.3-(Sr 2AlTaO6)0.7 (LSAT) substrates, this transition is lost. It has been reported in the literature that depositing NSMO on (110)-oriented STO allows for the transition to reemerge due to the partial epitaxial growth, where the NSMO film is strained along the [001] surface axis and partially relaxed along the [11¯0] surface axis. This allows the NSMO film enough

  16. Diffusion and crystal growth in plasma deposed thin ITO films

    International Nuclear Information System (INIS)

    Steffen, H.; Wulff, H.; Quaas, M.; Tun, Tin Maung.; Hipple, R.

    2000-01-01

    Tin-doped indium oxide (ITO) films were deposited by means of DC-planar magnetron sputtering. A metallic In/Sn (90/10) target an Ar/O 2 gas mixture were used. The oxygen flow was varied between 0 and 2 sccm. Substrate voltages between 0 and -100 V were used. With increasing oxygen flow film structure and composition change from crystalline metallic In/Sn to amorphous ITO. Simultaneously the deposition rate decreases and the film density increases. The diffusion of oxygen into metallic In/Sn films and the amorphous-to-crystalline transformation of ITO were studied using in situ grazing incidence X-ray diffractometry (GIXRD), grazing incidence reflectometry (GIXR), and AFM. From the X-ray integral intensities diffusion constants, activation energies of the diffusion, reaction order and activation energy of the crystal growth were extracted. (authors)

  17. The growth and characterisation of YBa2Cu3O7-δ superconducting thin films

    International Nuclear Information System (INIS)

    McCurry, M.P.

    1999-02-01

    The normal state properties of YBa 2 Cu 3 O 7-δ (YBCO) are not completely understood. It is known that the oxygen doping play a large part in determining these properties. The optical conductivity of a series of c-axis YBCO thin films was investigated in this thesis. The films were grown on (100) MgO substrates using a pulsed laser deposition (PLD) system and characterised using X-ray diffraction, atomic force microscopy and resistance-temperature measurements. The optimum parameters for c-axis YBCO thin film growth were determined by systematically varying the main deposition parameters. The best quality films had a transition temperature T c ∼ 88K, with a transition width ∼ 1-2K. Critical current densities of J c ∼ 10 7 Acm -2 were obtained. Substrate and target morphology affected the quality of the films. a-axis YBCO films were grown using a PrBa 2 Cu 3 O 7 (PBCO) film as a template for growth. The choice of target and substrate were again important, with a smooth substrate essential for the multi-layering. T c ∼ 83K and J c ∼ 10 6 Acm -2 were the best values obtained. These values compare with data published on the 'best' YBCO films deposited by PLD. A series of c-axis films was controllably under-doped using an ex-situ annealing process. The as-grown films were assumed to be optimally doped with δ ∼ 0.05. Doping levels in the 'metallic' region, 0.05 -2 mbar. Another tetragonal film was obtained by cooling it after deposition in a nitrogen atmosphere. Neither had a superconducting transition; the c-axes of both films were elongated. The films could be successfully re-doped with oxygen, with a subsequent return to optimal values of T c and c-axis lattice parameter. The dielectric function of optimally doped and under-doped c-axis YBCO films was determined using the attenuated total reflection (ATR) technique. This data was obtained at a fixed frequency of 2984 cm -1 , (0.366eV), at temperatures ranging from 300K to 80K. The data was analysed in

  18. solution growth and characterization of copper oxide thin films ...

    African Journals Online (AJOL)

    Thin films of copper oxide (CuO) were grown on glass slides by using the solution growth technique. Copper cloride (CuCl ) and potassium telluride (K T O ) were used. Buffer 2 2e 3 solution was used as complexing agent. The solid state properties and optical properties were obtained from characterization done using PYE ...

  19. Optimizing growth conditions for electroless deposition of Au films ...

    Indian Academy of Sciences (India)

    Unknown

    Optimizing growth conditions for electroless deposition of Au films on. Si(111) substrates. BHUVANA and G U KULKARNI*. Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for. Advanced Scientific Research, Jakkur PO, Bangalore 560 064, India. MS received 24 March 2006.

  20. Low temperature CVD growth of ultrathin carbon films

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2016-05-01

    Full Text Available We demonstrate the low temperature, large area growth of ultrathin carbon films by chemical vapor deposition under atmospheric pressure on various substrates. In particularly, uniform and continuous carbon films with the thickness of 2-5 nm were successfully grown at a temperature as low as 500 oC on copper foils, as well as glass substrates coated with a 100 nm thick copper layer. The characterizations revealed that the low-temperature-grown carbon films consist on few short, curved graphene layers and thin amorphous carbon films. Particularly, the low-temperature grown samples exhibited over 90% transmittance at a wavelength range of 400-750 nm and comparable sheet resistance in contrast with the 1000oC-grown one. This low-temperature growth method may offer a facile way to directly prepare visible ultrathin carbon films on various substrate surfaces that are compatible with temperatures (500-600oC used in several device processing technologies.

  1. Visualization modeling of thin film growth in photodeposition processes

    International Nuclear Information System (INIS)

    Mirchin, N.; Sidi, M.; Muchnik, Y.; Peled, A.

    2003-01-01

    A computer visualization technique, which analyzes and predicts the spatio-temporal evolution of thin film deposition and growth processes is given. It relies on microscopy sampled or computer generated synthetic micrographs of particles. These are then simulated for deposition, aggregation and coagulation during thin film growth by frequency domain transform techniques. Particle sources and diffusion operators on surfaces are used to predict with high temporal resolution, unattained by real world microscopy the surface structure evolution as time samples and time movies. The simulation program was used to investigate deposition and diffusive profiles in photodeposition experiments, starting from initial synthetic micrographs based on real world scanning electron microscopy (SEM) images. The surface microstructure time 'tracking' scheme described here relies on transforming the original image of the deposited particles into a Fourier spatial frequency domain image. The physical models used are that of a material random deposition source and subsequent surface redistribution due to diffusion and other coalescence material surface flow mechanisms. The 2-D inverse Fourier transform (IFT) is finally used to obtain back the real space-time images representing the surface spatio-temporal films morphology changes. False color representation of the images allows for a better discrimination of the films growing details especially during the fast pre-compact thin film layer formation on the substrate

  2. Visualization modeling of thin film growth in photodeposition processes

    Energy Technology Data Exchange (ETDEWEB)

    Mirchin, N.; Sidi, M.; Muchnik, Y.; Peled, A

    2003-03-15

    A computer visualization technique, which analyzes and predicts the spatio-temporal evolution of thin film deposition and growth processes is given. It relies on microscopy sampled or computer generated synthetic micrographs of particles. These are then simulated for deposition, aggregation and coagulation during thin film growth by frequency domain transform techniques. Particle sources and diffusion operators on surfaces are used to predict with high temporal resolution, unattained by real world microscopy the surface structure evolution as time samples and time movies. The simulation program was used to investigate deposition and diffusive profiles in photodeposition experiments, starting from initial synthetic micrographs based on real world scanning electron microscopy (SEM) images. The surface microstructure time 'tracking' scheme described here relies on transforming the original image of the deposited particles into a Fourier spatial frequency domain image. The physical models used are that of a material random deposition source and subsequent surface redistribution due to diffusion and other coalescence material surface flow mechanisms. The 2-D inverse Fourier transform (IFT) is finally used to obtain back the real space-time images representing the surface spatio-temporal films morphology changes. False color representation of the images allows for a better discrimination of the films growing details especially during the fast pre-compact thin film layer formation on the substrate.

  3. Magnesium growth in magnesium deuteride thin films during deuterium desorption

    Energy Technology Data Exchange (ETDEWEB)

    Checchetto, R., E-mail: riccardo.checchetto@unitn.it [Dipartimento di Fisica and CNISM, Università di Trento, Via Sommarive 14, I-38123 Trento (Italy); Miotello, A. [Dipartimento di Fisica and CNISM, Università di Trento, Via Sommarive 14, I-38123 Trento (Italy); Mengucci, P.; Barucca, G. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Università Politecnica delle Marche, I-60131 Ancona (Italy)

    2013-12-15

    Highlights: ► Highly oriented Pd-capped magnesium deuteride thin films. ► The MgD{sub 2} dissociation was studied at temperatures not exceeding 100 °C. ► The structure of the film samples was analyzed by XRD and TEM. ► The transformation is controlled by the re-growth velocity of the Mg layers. ► The transformation is thermally activated, activation energy value of 1.3 ± 0.1 eV. -- Abstract: Pd- capped nanocrystalline magnesium thin films having columnar structure were deposited on Si substrate by e-gun deposition and submitted to thermal annealing in D{sub 2} atmosphere to promote the metal to deuteride phase transformation. The kinetics of the reverse deuteride to metal transformation was studied by Thermal Desorption Spectroscopy (TDS) while the structure of the as deposited and transformed samples was analyzed by X-rays diffraction and Transmission Electron Microscopy (TEM). In Pd- capped MgD{sub 2} thin films the deuteride to metal transformation begins at the interface between un-reacted Mg and transformed MgD{sub 2} layers. The D{sub 2} desorption kinetics is controlled by MgD{sub 2}/Mg interface effects, specifically the re-growth velocity of the Mg layers. The Mg re-growth has thermally activated character and shows an activation energy value of 1.3 ± 0.1 eV.

  4. Giant secondary grain growth in Cu films on sapphire

    Directory of Open Access Journals (Sweden)

    David L. Miller

    2013-08-01

    Full Text Available Single crystal metal films on insulating substrates are attractive for microelectronics and other applications, but they are difficult to achieve on macroscopic length scales. The conventional approach to obtaining such films is epitaxial growth at high temperature using slow deposition in ultrahigh vacuum conditions. Here we describe a different approach that is both simpler to implement and produces superior results: sputter deposition at modest temperatures followed by annealing to induce secondary grain growth. We show that polycrystalline as-deposited Cu on α-Al2O3(0001 can be transformed into Cu(111 with centimeter-sized grains. Employing optical microscopy, x-ray diffraction, and electron backscatter diffraction to characterize the films before and after annealing, we find a particular as-deposited grain structure that promotes the growth of giant grains upon annealing. To demonstrate one potential application of such films, we grow graphene by chemical vapor deposition on wafers of annealed Cu and obtain epitaxial graphene grains of 0.2 mm diameter.

  5. Diamond film growth with modification properties of adhesion between substrate and diamond film

    Directory of Open Access Journals (Sweden)

    Setasuwon P.

    2004-03-01

    Full Text Available Diamond film growth was studied using chemical vapor deposition (CVD. A special equipment was build in-house, employing a welding torch, and substrate holder with a water-cooling system. Acetylene and oxygen were used as combustion gases and the substrate was tungsten carbide cobalt. It was found that surface treatments, such as diamond powder scratching or acid etching, increase the adhesion and prevent the film peel-off. Diamond powder scratching and combined diamond powder scratching with acid etching gave the similar diamond film structure with small grain and slightly rough surface. The diamond film obtained with both treatments has high adhesion and can withstand internal stress better than ones obtained by untreated surface or acid etching alone. It was also found that higher substrate temperature produced smoother surface and more uniform diamond grain.

  6. Solution growth, characterization and applications of zinc sulphide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ndukwe, I C [School of Physical Sciences, Abia State University, Uturu, Abia State (Nigeria)

    1996-04-29

    Zinc sulphide (ZnS) thin films were successfully deposited on glass substrates under varying deposition conditions using the electroless or solution growth technique. The film properties investigated include their transmittance/reflectance/absorbance spectra, bandgap, optical constants, and thicknesses. Films grown under certain parametric conditions were found to exhibit high transmittance (64-98%), low absorbance, and low reflectance in the ultraviolet (uv)/visible/near infrared (nir) regions up to 1.00 {mu}m. Those obtained under other conditions exhibited high transmittance (78-98%) and low absorbance (0.01-0.1) in the uv/visible regions but low transmittance (30-37) and high absorbance (0.56) in the nir region. These characteristics revealed their suitability for various solar device applications. Bandgap range E{sub g}=3.7-3.8 eV and thickness range t=0.07 - 0.73 {mu}m were obtained.

  7. Composite depth dose measurement for total skin electron (TSE) treatments using radiochromic film

    International Nuclear Information System (INIS)

    Gamble, Lisa M; Farrell, Thomas J; Jones, Glenn W; Hayward, Joseph E

    2003-01-01

    Total skin electron (TSE) radiotherapy is routinely used to treat cutaneous T-cell lymphomas and can be implemented using a modified Stanford technique. In our centre, the composite depth dose for this technique is achieved by a combination of two patient positions per day over a three-day cycle, and two gantry angles per patient position. Due to patient morphology, underdosed regions typically occur and have historically been measured using multiple thermoluminescent dosimeters (TLDs). We show that radiochromic film can be used as a two-dimensional relative dosimeter to measure the percent depth dose in TSE radiotherapy. Composite depth dose curves were measured in a cylindrical, polystyrene phantom and compared with TLD data. Both multiple films (1 film per day) and a single film were used in order to reproduce a realistic clinical scenario. First, three individual films were used to measure the depth dose, one per treatment day, and then compared with TLD data; this comparison showed a reasonable agreement. Secondly, a single film was used to measure the dose delivered over three daily treatments and then compared with TLD data; this comparison showed good agreement throughout the depth dose, which includes doses well below 1 Gy. It will be shown that one piece of radiochromic film is sufficient to measure the composite percent depth dose for a TSE beam, hence making radiochromic film a suitable candidate for monitoring underdosed patient regions

  8. Grain Growth in Nanocrystalline Mg-Al Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Kruska, Karen; Rohatgi, Aashish; Vemuri, Venkata Rama Ses; Kovarik, Libor; Moser, Trevor H.; Evans, James E.; Browning, Nigel D.

    2017-10-05

    An improved understanding of grain growth kinetics in nanocrystalline materials, and in metals and alloys in general, is of continuing interest to the scientific community. In this study, Mg - Al thin films containing ~10 wt.% Al and with 14.5 nm average grain size were produced by magnetron-sputtering and subjected to heat-treatments. The grain growth evolution in the early stages of heat treatment at 423 K (150 °C), 473 K (200 °C) and 573K (300 °C) was observed with transmission electron microscopy and analyzed based upon the classical equation developed by Burke and Turnbull. The grain growth exponent was found to be 7±2 and the activation energy for grain growth was 31.1±13.4 kJ/mol, the latter being significantly lower than in bulk Mg-Al alloys. The observed grain growth kinetics are explained by the Al supersaturation in the matrix and the pinning effects of the rapidly forming beta precipitates and possibly shallow grain boundary grooves. The low activation energy is attributed to the rapid surface diffusion which is dominant in thin film systems.

  9. Corrosion resistance and biocompatibility of zirconium oxynitride thin film growth by RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Cubillos, G. I.; Olaya, J. J.; Clavijo, D.; Alfonso, J. E. [Universidad Nacional de Colombia, Carrera 45 No. 26-85, AA 14490 Bogota D. C. (Colombia); Bethencourt, M., E-mail: jealfonsoo@unal.edu.co [Universidad de Cadiz, Centro Andaluz de Ciencia y Tecnologia Marinas, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Av. Republica de Saharaui, Puerto Real, E-11510 Cadiz (Spain)

    2012-07-01

    Thin films of zirconium oxynitride were grown on common glass, silicon (100) and stainless steel 316 L substrates using the reactive RF magnetron sputtering technique. The films were analyzed through structural, morphological and biocompatibility studies. The structural analysis was carried out using X-ray diffraction (XRD), and the morphological analysis was carried out using scanning electron microscopy (Sem) and atomic force microscopy (AFM). These studies were done as a function of growth parameters, such as power applied to the target, substrate temperature, and flow ratios. The corrosion resistance studies were made on samples of stainless steel 316 L coated and uncoated with Zr{sub x}N{sub y}O films, through of polarization curves. The studies of biocompatibility were carried out on zirconium oxynitride films deposited on stainless steel 316 L through proliferation and cellular adhesion. The XRD analysis shows that films deposited at 623 K, with a flow ratio {Phi}N{sub 2}/{Phi}O{sub 2} of 1.25 and a total deposit time of 30 minutes grew preferentially oriented along the (111) plane of the zirconium oxynitride monoclinic phase. The Sem analyses showed that the films grew homogeneously, and the AFM studies indicated that the average rugosity of the film was 5.9 nm and the average particle size was 150 nm. The analysis of the corrosion resistant, shows that the stainless steel coated with the film was increased a factor 10. Finally; through the analysis of the biocompatibility we established that the films have a better surface than the substrate (stainless steel 316 L) in terms of the adhesion and proliferation of bone cells. (Author)

  10. Synthesis and biological characterization of zirconium oxynitride thin film growth by radio-frequency sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Cubillos, G.I. [Departamento de Química, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia); Olaya, J.J. [Facultad de Ingeniería, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia); Clavijo, D. [Facultad de Medicina, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia); Alfonso, J.E., E-mail: jealfonsoo@unal.edu.co [Grupo de materiales con Aplicaciones Tecnológicas, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia); Cardozo, C. [Instituto de Biotecnología, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia)

    2013-02-01

    Thin films of zirconium oxynitride were grown on common glass, silicon substrates (100) and on stainless steel 316L using the reactive RF magnetron sputtering technique. The films were analyzed through structural, morphological, and biocompatibility studies. The structural analysis was carried out using X-ray diffraction (XRD), and the morphological analysis was carried out using scanning electron microscopy (SEM) and atomic force microscopy (AFM). These studies were done as a function of growth parameters, such as power applied to the target, substrate temperature, and flow ratios. The studies of biocompatibility were carried out on zirconium oxynitride films deposited on stainless steel 316L through proliferation and cellular adhesion. The XRD analysis showed that films deposited at 623 K, with a flow ratio ΦN{sub 2}/ΦO{sub 2} of 1.25 and a total deposit time of 30 min grew preferentially oriented along the (111) plane of the zirconium oxynitride monoclinic phase. The SEM analyses showed that the films grew homogeneously, and the AFM studies indicated that the average rugosity of the film was 5.9 nm and the average particle size was 150 nm. Finally, through the analysis of the biocompatibility, we established that the films have a better surface than the substrate (stainless steel 316L) in terms of adhesion and proliferation of bone cells. - Highlights: ►ZrO{sub x}N{sub y} thin films were deposited using reactive radio-frequency magnetron sputtering. ►We studied the effect of deposition parameters on ZrO{sub x}N{sub y} thin films microstructure. ►We have been able to grow bone cells on ZrO{sub x}N{sub y} coated stainless steel 316L.

  11. Influence of argon dilution on growth and properties of hydrogenated nanocrystalline silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Parashar, A. [Plasma Processed Materials Group, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Department of Physics and Astro Physics, University of Delhi, Delhi 110007 (India); Kumar, Sushil; Gope, Jhuma; Rauthan, C.M.S.; Dixit, P.N. [Plasma Processed Materials Group, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Hashmi, S.A. [Department of Physics and Astro Physics, University of Delhi, Delhi 110007 (India)

    2010-05-15

    The effect of argon concentration (66-87%) in total gaseous mixture (SiH{sub 4}+H{sub 2}+Ar) on growth and properties of hydrogenated nanocrystalline silicon films deposited by RF (13.56 MHz) PECVD technique was investigated. Raman and XRD measurements revealed increasing argon fraction favored enhancement of crystallinity, enlargement of crystallites and relaxation of strained bonds. Photoluminescence spectra of nc-Si:H films exhibited two radiative transitions in the photon energy ranges of 2.8-3.1 eV and 1.6-2.1 eV. The high energy PL peaks are attributed to surface effect of the films whereas peaks in the range of 1.6-2.1 eV are due to nanocrystallinity in the films. Argon dilution also helped enhancement of deposition rate and conductivity of the films. A film deposited at 81% of argon fraction possesses high crystallinity (75%), conductivity in the order of 10{sup -5} ({omega} cm){sup -1}, size of the crystallite (Raman=12 nm, XRD=18 nm), and low residual stress (125 MPa). (author)

  12. Solution growth of Tb doped Gd_2O_3 film

    International Nuclear Information System (INIS)

    Ghosh, M.; Pitale, S.; Desai, D.G.; Patra, G.D.; Sen, S.; Gadkari, S.C.

    2016-01-01

    Nanomaterials of Gd_2O_3 have proven applications in medical imaging and cancer therapy due to the presence of element Gd. Also Gd_2O_3 films have been grown by vapor phase method as well as self assembly in solution and studied as a high-k dielectric and efficient luminescence material. Here, we report a method to obtain Tb doped Gd_2O_3 film by solution growth method followed by suitable heat treatment. Uniform films of Tb doped Gadolinium hydroxycarbonate have been deposited on fused quartz substrates kept inside a solution containing gadolinium nitrate, terbium nitrate and Urea maintained at 90°C. Gadolinium hydroxy-carbonate films are then treated at 800°C for 2 hour to obtain Tb doped cubic Gd_2O_3 as confirmed by X-ray diffraction measurement. The photoluminescence spectra display characteristic Tb emission at 544 nm when excited at 285 nm. The lifetime of Tb emission is found to be of the order of few microseconds. (author)

  13. Formation of resonant bonding during growth of ultrathin GeTe films

    NARCIS (Netherlands)

    Wang, Ruining; Zhang, Wei; Momand, Jamo; Ronneberger, Ider; Boschker, Jos E.; Mazzarello, Riccardo; Kooi, Bart J.; Riechert, Henning; Wuttig, Matthias; Calarco, Raffaella

    2017-01-01

    A highly unconventional growth scenario is reported upon deposition of GeTe films on the hydrogen passivated Si(111) surface. Initially, an amorphous film forms for growth parameters that should yield a crystalline material. The entire amorphous film then crystallizes once a critical thickness of

  14. Film growth kinetics and electric field patterning during electrospray deposition of block copolymer thin films

    Science.gov (United States)

    Toth, Kristof; Hu, Hanqiong; Choo, Youngwoo; Loewenberg, Michael; Osuji, Chinedum

    The delivery of sub-micron droplets of dilute polymer solutions to a heated substrate by electrospray deposition (ESD) enables precisely controlled and continuous growth of block copolymer (BCP) thin films. Here we explore patterned deposition of BCP films by spatially varying the electric field at the substrate using an underlying charged grid, as well as film growth kinetics. Numerical analysis was performed to examine pattern fidelity by considering the trajectories of charged droplets during flight through imposed periodic field variations in the vicinity of the substrate. Our work uncovered an unexpected modality for improving the resolution of the patterning process via stronger field focusing through the use of a second oppositely charged grid beneath a primary focusing array, with an increase in highly localized droplet deposition on the intersecting nodes of the grid. Substrate coverage kinetics are considered for homopolymer deposition in the context of simple kinetic models incorporating temperature and molecular weight dependence of diffusivity. By contrast, film coverage kinetics for block copolymer depositions are additionally convoluted with preferential wetting and thickness-periodicity commensurability effects. NSF GRFP.

  15. Effect of deposition conditions on the growth rate and electrical properties of ZnO thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Roro, K.T.; Botha, J.R.; Leitch, A.W.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)

    2008-07-01

    ZnO thin films have been grown on glass substrates by MOCVD. The effect of deposition conditions such as VI/II molar ratio, DEZn flow rate and total reactor pressure on the growth rate and electrical properties of the films was studied. It is found that the growth rate decreases with an increase in the VI/II molar ratio. This behaviour is ascribed to the competitive adsorption of reactant species on the growth surface. The growth rate increases with an increase in DEZn flow rate, as expected. It is shown that the carrier concentration is independent of the DEZn flow rate. An increase in the total reactor pressure yields a decrease in growth rate. This phenomenon is attributed to the depletion of the gas phase due to parasitic prereactions between zinc and oxygen species at high pressure. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Texture control and growth mechanism of WSe{sub 2} film prepared by rapid selenization of W film

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongchao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Chongyi Zhangyuan Tungsten Industry Corporation Limited, Ganzhou 341300 (China); Gao, Di; Li, Kun; Pang, Mengde; Xie, Senlin [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Liu, Rutie, E-mail: llrrtt@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Zou, Jianpeng [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2017-02-01

    Highlights: • We present a highly efficient method for preparing WSe{sub 2} film by rapid selenization. • The W film phase composition has little effect on WSe{sub 2} film orientation. • W film density is a critical factor that influences the WSe{sub 2} orientation. • A growth model was proposed for two kinds of WSe{sub 2} film textures. - Abstract: The tungsten diselenide (WSe{sub 2}) films with different orientation present unique properties suitable for specific applications, such as WSe{sub 2} with a C-axis⊥substrate for optoelectronics and WSe{sub 2} with a C-axis // substrate for electrocatalysts. Orientation control of WSe{sub 2} is essential for realizing the practical applications. In this letter, a WSe{sub 2} film has been prepared via rapid selenization of a magnetron-sputtered tungsten (W) film. The influence of the magnetron-sputtered W film on WSe{sub 2} film growth was studied systematically. Scanning electron microscopy, X-ray diffractometry and high-resolution transmission electron microscopy were used to evaluate the morphology, microstructure and phase composition of the W and WSe{sub 2} films. The substrate temperature has a significant effect on the W film phase composition, but little effect on the WSe{sub 2} film orientation. The WSe{sub 2} orientation can be controlled by changing the W film microstructure. A dense W film that is deposited at low pressure is conducive to the formation of WSe{sub 2} with a C-axis⊥substrate, whereas a porous W film deposited at high pressure favors the formation of WSe{sub 2} with a C-axis // substrate. A growth model for the WSe{sub 2} film with different texture has been proposed based on the experimental results. The direction of selenium (Se) vapor diffusion differs at the top and side surfaces. This is a key factor for the preparation of anisotropic WSe{sub 2} films. Highly oriented WSe{sub 2} films with a C-axis⊥substrate grow from the dense W film deposited at low pressure because Se vapor

  17. Exogenous application of plant growth regulators increased the total ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... the exogenous application of flavonoids reports plant growth regulation ... method used for extraction and quantification of endogenous gibberellins was ... 365 nm) while separation was done on a C18 reverse-phase HPLC.

  18. Buckyball microwave plasmas: Fragmentation and diamond-film growth

    International Nuclear Information System (INIS)

    Gruen, D.M.; Liu, Shengzhong; Krauss, A.R.; Pan, Xianzheng.

    1993-08-01

    Microwave discharges (2.45 GHz) have been generated in C 60 -containing Ar produced by flowing Ar over fullerene-containing soot. Optical spectroscopy shows that the spectrum is dominated by the d 3 Πg-a 3 Πu Swan bands of C 2 and particularly the Δv = -2, -1, 0, +1, and +2 sequences. These results give direct evidence that C 2 is one of the products of C 60 fragmentation brought about, at least in part, by collisionally induced dissociation (CID). C 60 has been used as a precursor in a plasma-enhanced chemical vapor deposition (PECVD) experiment to grow diamond-thin films. The films, grown in an Ar/H 2 gas mixture (0.14% carbon content, 100 Torr, 20 sccm Ar, 4 sccm H 2 , 1500 W, 850 degree C substrate temperature), were characterized with SEM, XRD, and Raman spectroscopy. Growth rate was found to be ∼ 0.6 μ/hr. Assuming a linear dependence on carbon concentration, a growth rate at least six times higher than commonly observed using methane as a precursor, would be predicted at a carbon content of 1% based on C 60 . Energetic and mechanistic arguments are advanced to rationalize this result based on C 2 as the growth species

  19. Growth of AlN films and their characterization

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Rakesh B.; Gao, Ying; Zhang, Jianping; Qhaleed Fareed, R.S.; Gaska, Remis [Sensor Electronic Technology, Inc., 1195 Atlas Rd., Columbia, SC 29209 (United States); Li, Jiawei; Arjunan, Arulchakkravarthi; Yang, Jinwei; Asif Khan, M. [Department of Electrical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Kuokstis, Edmundas [MTMI, Vilnius University, Vilnius (Lithuania)

    2006-06-15

    Single crystal AlN layers have been produced by migration enhanced metal organic chemical vapor deposition (MEMOCVD), hydride vapor phase epitaxy (HVPE) and their combination. The growth was carried out on 2'' basal plane sapphire substrates. In MEMOCVD, the duration and waveforms of precursors were varied to achieve better surface mobility and thus better atomic incorporation. It resulted in superior layer quality templates with the narrowest (002) X-ray rocking curve full width half maximum (FWHM). Such high quality AlN templates were used as seeds for subsequent HVPE growth. Thick films with thickness ranging from 1-25 {mu}m have been grown by HVPE with growth rates as high as 200 {mu}m/min, highest ever reported. Films grown by the two methods have been extensively characterized by Nomarski microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), high-resolution X-ray diffractometry (HRXRD), and photoluminescence (PL). (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Atomic Layer Control of Thin Film Growth Using Binary Reaction Sequence Chemistry

    National Research Council Canada - National Science Library

    George, Steven

    1997-01-01

    Our research is focusing on the atomic layer control of thin film growth. Our goal is to deposit films with precise control of thickness and conformality on both flat and high aspect ratio structures...

  1. Analysis of thin-film polymers using attenuated total internal reflection-Raman microspectroscopy.

    Science.gov (United States)

    Tran, Willie; Tisinger, Louis G; Lavalle, Luis E; Sommer, André J

    2015-01-01

    Two methods commonly employed for molecular surface analysis and thin-film analysis of microscopic areas are attenuated total reflection infrared (ATR-IR) microspectroscopy and confocal Raman microspectroscopy. In the former method, the depth of the evanescent probe beam can be controlled by the wavelength of light, the angle of incidence, or the refractive index of the internal reflection element. Because the penetration depth is proportional to the wavelength of light, one could interrogate a smaller film thickness by moving from the mid-infrared region to the visible region employing Raman spectroscopy. The investigation of ATR Raman microspectroscopy, a largely unexplored technique available to Raman microspectroscopy, was carried out. A Renishaw inVia Raman microscope was externally modified and used in conjunction with a solid immersion lens (SIL) to perform ATR Raman experiments. Thin-film polymer samples were analyzed to explore the theoretical sampling depth for experiments conducted without the SIL, with the SIL, and with the SIL using evanescent excitation. The feasibility of micro-ATR Raman was examined by collecting ATR spectra from films whose thickness measured from 200 to 60 nm. Films of these thicknesses were present on a much thicker substrate, and features from the underlying substrate did not become visible until the thin film reached a thickness of 68 nm.

  2. A nonlinear model for surface segregation and solute trapping during planar film growth

    International Nuclear Information System (INIS)

    Han, Xiaoying; Spencer, Brian J.

    2007-01-01

    Surface segregation and solute trapping during planar film growth is one of the important issues in molecular beam epitaxy, yet the study on surface composition has been largely restricted to experimental work. This paper introduces some mathematical models of surface composition during planar film growth. Analytical solutions are obtained for the surface composition during growth

  3. Growth, characterization and device development in monocrystalline diamond films

    Science.gov (United States)

    Davis, R. F.; Glass, J. T.; Nemanich, R. J.; Bozeman, S. P.; Sowers, A. T.

    1995-06-01

    Experimental and theoretical studies concerned with interface interactions of diamond with Si, Ni, and Ni3Si substrates have been conducted. Oriented diamond films deposited on (100) Si were characterized by polar Raman, polar x-ray diffraction (XRD), and cross-sectional high resolution transmission electron microscopy (HRTEM). These sutides showed that the diamond(100)/Si(100) interface adopted the 3:2-match arrangement rather than a 45 deg rotation. Extended Hueckel tight-binding (EHTB) electronic structure calculations for a model system revealed that the interface interaction favors the 3:2-match arrangement. Growth on polycrystalline Ni3Si resulted in oriented diamond particles; under the same growth conditions, graphite was formed on the nickel substrate. Our EHTB electronic structure calculations showed that the (111) and (100) surfaces of Ni3Si have a strong preference for diamond nucleation over graphite nucleation, but this was not the case for the (111) and (100) surfaces of Ni.

  4. Growth modes of pentacene films obtained by pulsed laser deposition

    International Nuclear Information System (INIS)

    Wisz, G.; Kuzma, M.; Virt, I.; Sagan, P.; Rudyj, I.

    2011-01-01

    Thin pentacene films were deposited on KCl and ITO/glass substrates by the pulsed laser deposition method (PLD) using a YAG:Nd 3+ laser with a second harmonic (λ = 532 nm). We compared the structure of the layer on differently oriented substrates with respect to the pentacene plasma plume - vertical and parallel orientation. The structure of the layers formed was examined using SEM, RHEED and THEED methods. The lattice parameters of the layer deposited on KCl were determined from THEED pattern (a = 5.928 A, b 7.874 A, c = 14,98 A, α = 76.54 o , β 75.17 o , γ = 89.20 o ). The preferred direction [11-bar 0] of the layer growth on KCl substrate was addressed. The effect of the substrate orientation results in a different growth mode of the layers.

  5. XRD total scattering of the CZTS nanoparticle absorber layer for the thin film solar cells

    DEFF Research Database (Denmark)

    Symonowicz, Joanna; Jensen, Kirsten M. Ø.; Engberg, Sara Lena Josefin

    Cu2ZnSnS4 (CZTS) thin film solar cells are cheap, non-toxic and present an efficiency up to 9,2% [1]. They can be easily manufactured by the deposition of the nanoparticle ink as a thin film followed by a thermal treatment to obtain large grains [2]. Therefore, CZTS has the potential...... to revolutionize the solar energy market. However, to commercialize CZTS nanoparticle thin films, the efficiency issues must yet be resolved. In order to do so, it is vital to understand in detail their nanoscale atomic structure. CZTS crystallize in the kesterite structure, where Cu and Zn is distributed between......-ray Diffraction data with X-ray total scattering with Pair Distribution Function analysis. Powder neutron diffraction will furthermore allow characterization of the cation disorder on the metal sites in the kesterite structure. The nanoparticle ink is also characterized by XRD, EDS, and Raman spectroscopy...

  6. Growth of Cu thin films by the successive ionic layer adsorption and reaction (SILAR) method

    International Nuclear Information System (INIS)

    Lindroos, S.; Ruuskanen, T.; Ritala, M.; Leskelae, M.

    2004-01-01

    Copper thin films were grown on reduced indium tin oxide, molybdenum and polymer substrates using successive ionic layer adsorption and reaction (SILAR) method. Copper films were grown sequentially in a controlled way using simple copper salt and basic solution of formaldehyde as precursors. The copper films were polycrystalline with no preferred orientation as characterised by X-ray diffraction. On all substrates, the growth was clearly island growth in the beginning but after the whole surface was covered, the growth was more homogeneous

  7. Nucleation, growth and evolution of calcium phosphate films on calcite.

    Science.gov (United States)

    Naidu, Sonia; Scherer, George W

    2014-12-01

    Marble, a stone composed of the mineral calcite, is subject to chemically induced weathering in nature due to its relatively high dissolution rate in acid rain. To protect monuments and sculpture from corrosion, we are investigating the application of thin layers of hydroxyapatite (HAP) onto marble. The motivation for using HAP is its low dissolution rate and crystal and lattice compatibility with calcite. A mild, wet chemical synthesis route, in which diammonium hydrogen phosphate salt was reacted with marble, alone and with cationic and anionic precursors under different reaction conditions, was used to produce inorganic HAP layers on marble. Nucleation and growth on the calcite substrate was studied, as well as metastable phase evolution, using scanning electron microscopy, grazing incidence X-ray diffraction, and atomic force microscopy. Film nucleation was enhanced by surface roughness. The rate of nucleation and the growth rate of the film increased with cationic (calcium) and anionic (carbonate) precursor additions. Calcium additions also influenced phase formation, introducing a metastable phase (octacalcium phosphate) and a different phase evolution sequence. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. In situ spectroscopic ellipsometry as a surface sensitive tool to probe thin film growth

    International Nuclear Information System (INIS)

    Liu, C.

    1999-01-01

    Sputtered thin film and multilayer x-ray mirrors are made routinely at the Advanced Photon Source (APS) for the APS users. Precise film growth control and characterization are very critical in fabricating high-quality x-ray mirrors. Film thickness calibrations are carried out using in situ and ex situ spectroscopic ellipsometry, interferometry, and x-ray scattering. To better understand the growth and optical properties of different thin film systems, we have carried out a systematic study of sputtered thin films of Au, Rh, Pg Pd, Cu, and Cr, using in situ ellipsometry. Multiple data sets were obtained in situ for each film material with incremental thicknesses and were analyzed with their correlation in mind. We found that in situ spectroscopic ellipsometry as a surface-sensitive tool can also be used to probe the growth and morphology of the thin film system. This application of in situ spectroscopic ellipsometry for metal thin film systems will be discussed

  9. Temperature-dependent evolution of chemisorbed digermane in Ge thin film growth

    International Nuclear Information System (INIS)

    Eres, D.; Sharp, J.W.

    1992-01-01

    The formation and evolution of chemisorbed digermane layers in context with germanium thin film growth was investigated by time- resolved surface reflectometry. Modulation of the source gas supply made possible the separation and independent study of the temperature dependence of the adsorption and desorption processes. The regeneration of active sites by molecular hydrogen desorption was identified as the rate-limiting step at low substrate temperatures. A dynamic method of thin film growth was demonstrated by repetitively replenishing the active film growth sites regenerated between two successive source gas pulses. The film growth rate was shown to be related to the substrate temperature and the delay time between successive source gas pulses

  10. Investigation of Au/Au(100) film growth with energetic deposition by kinetic Monte Carlo simulation

    International Nuclear Information System (INIS)

    Zhang Qingyu; Ma Tengcai; Pan Zhengying; Tang Jiayong

    2000-01-01

    The Au/Au(100) epitaxial growth with energetic deposition was simulated by using kinetic Monte Carlo method. The influences of energetic atoms on morphology and atomistic processes in the early stage of film growth were investigated. The reentrant layer-by-layer growth was observed in the temperature range of 450 K to 100 K. The authors found the energetic atoms can promote the nucleation and island growth in the early stages of film growth and enhance the smoothness of film surface at temperatures of film growth in 3-dimensional mode and in quasi-two-dimensional mode. The atomistic mechanism that promotes the nucleation and island growth and enhances the smoothness of film surface is discussed

  11. Nanowire growth from the viewpoint of the thin film polylayer growth theory

    Science.gov (United States)

    Kashchiev, Dimo

    2018-03-01

    The theory of polylayer growth of thin solid films is employed for description of the growth kinetics of single-crystal nanowires. Expressions are derived for the dependences of the height h and radius r of a given nanowire on time t, as well as for the h(r) dependence. These dependences are applicable immediately after the nanowire nucleation on the substrate and thus include the period during which the nucleated nanowire changes its shape from that of cap to that of column. The analysis shows that the nanowire cap-to-column shape transition is continuous and makes it possible to kinetically define the nanowire shape-transition radius by means of the nanowire radial and axial growth rates. The obtained h(t), r(t) and h(r) dependences are found to provide a good description of available experimental data for growth of self-nucleated GaN nanowires by the vapor-solid mechanism.

  12. Effects of an ultraviolet-visible rays translation film on growth of leaf or root vegetables

    International Nuclear Information System (INIS)

    Hamamoto, H.; Ueno, K.; Yamazaki, K.

    2008-01-01

    A new film that absorbs ultraviolet radiation (UV) and fluoresces red light was tested as a rain shelter for the cultivation of turnip (Brassica rapa L.), spinach (Spinacia oleracea L.), and Welsh onion (Allium fistulosum L.). The effect of this UV-visible ray translation film on various growth parameters (height, fresh and dry weight, leaf area and leaf sheath diameter) was compared with those under normal clear film, new UV-cut film, and used UV-cut film respectively. The transmissivity of UV was about 70% for the normal clear film, about 20% for the UV-visible ray translation film and used UV-cut film, and about 10% for the new UV-cut film. The transmissivity of photosynthetically active radiation (PAR) was about 90% for the normal clear film and the new UV-cut film, and about 80% for the used UV-cut film, while the mean transmissivity of PAR was about 80% for the UV-visible ray translation film, with about 60% transmissivity of blue radiation and over 90% of red radiation. The UV-visible ray translation film did not promote the growth of turnip roots but did significantly promote the growth of spinaches and Welsh onions compared with the normal clear film. The UV-visible ray translation film cover promoted the growth of spinaches and Welsh onions to a similar or greater extent compared to the new UV-cut film and also to a greater extent compared to the used UV-cut film

  13. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K.; Ghosh, K.; Kahol, P.K. [Department of Physics, Astronomy and Materials Science, Missouri State University, Springfield, MO 65897 (United States); Yoon, J. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Guha, S. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)], E-mail: guhas@missouri.edu

    2008-08-30

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the {beta} phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films.

  14. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    International Nuclear Information System (INIS)

    Gupta, R.K.; Ghosh, K.; Kahol, P.K.; Yoon, J.; Guha, S.

    2008-01-01

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the β phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films

  15. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    Science.gov (United States)

    Gupta, R. K.; Ghosh, K.; Kahol, P. K.; Yoon, J.; Guha, S.

    2008-08-01

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the β phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films.

  16. Influence of deposition parameters on the refractive index and growth rate of diamond-like carbon films

    International Nuclear Information System (INIS)

    Zhang, G.F.; Zheng, X.; Guo, L.J.; Liu, Z.T.; Xiu, N.K.

    1994-01-01

    In order to use diamond-like carbon (DLC) films as protective and antireflection coatings for IR optical materials exposed to hostile environments, an investigation has been systematically conducted on the influence of the deposition parameters on the refractive index and growth rate of DLC films, which are two of the most important parameters in evaluating optical characteristics of antireflection coatings. The experimental results show that both the refractive index and growth rate of DLC films depend strongly on the negative d.c. bias voltage. The refractive index increases with increasing bias voltage and decreases with increasing partial pressure of the hydrocarbon gas and total flow rate of the mixture. The growth rate increases greatly when the bias voltage is larger than a threshold value. The various parameters which influence the structure and properties of DLC films are interrelated. Fourier transform IR spectroscopy results show that the strength of the C-H stretching absorption band in the range 3300-2850 cm -1 is gradually weakened with increasing negative bias voltage and argon concentration. High energy bombardment of the growing film plays an important role in the structure and hence the properties of DLC films. (orig.)

  17. Disilane as a growth rate catalyst of plasma deposited microcrystalline silicon thin films

    Science.gov (United States)

    Dimitrakellis, P.; Kalampounias, A. G.; Spiliopoulos, N.; Amanatides, E.; Mataras, D.; Lahootun, V.; Coeuret, F.; Madec, A.

    2016-07-01

    The effect of small disilane addition on the gas phase properties of silane-hydrogen plasmas and the microcrystalline silicon thin films growth is presented. The investigation was conducted in the high pressure regime and for constant power dissipation in the discharge with the support of plasma diagnostics, thin film studies and calculations of discharge microscopic parameters and gas dissociation rates. The experimental data and the calculations show a strong effect of disilane on the electrical properties of the discharge in the pressure window from 2 to 3 Torr that is followed by significant raise of the electron number density and the drop of the sheaths electric field intensity. Deposition rate measurements show an important four to six times increase even for disilane mole fractions as low as 0.3 %. The deposition rate enhancement was followed by a drop of the material crystalline volume fraction but films with crystallinity above 40 % were deposited with different combinations of total gas pressure, disilane and silane molar ratios. The enhancement was partly explained by the increase of the electron impact dissociation rate of silane which rises by 40% even for 0.1% disilane mole fraction. The calculations of the gas usage, the dissociation and the deposition efficiencies show that the beneficial effect on the growth rate is not just the result of the increase of Si-containing molecules density but significant changes on the species participating to the deposition and the mechanism of the film growth are caused by the disilane addition. The enhanced participation of the highly sticking to the surface radical such as disilylene, which is the main product of disilane dissociation, was considered as the most probable reason for the significant raise of the deposition efficiency. The catalytic effect of such type of radical on the surface reactivity of species with lower sticking probability is further discussed, while it is also used to explain the restricted

  18. Disilane as a growth rate catalyst of plasma deposited microcrystalline silicon thin films

    International Nuclear Information System (INIS)

    Dimitrakellis, P.; Amanatides, E.; Mataras, D.; Kalampounias, A. G.; Spiliopoulos, N.; Lahootun, V.; Coeuret, F.; Madec, A.

    2016-01-01

    The effect of small disilane addition on the gas phase properties of silane-hydrogen plasmas and the microcrystalline silicon thin films growth is presented. The investigation was conducted in the high pressure regime and for constant power dissipation in the discharge with the support of plasma diagnostics, thin film studies and calculations of discharge microscopic parameters and gas dissociation rates. The experimental data and the calculations show a strong effect of disilane on the electrical properties of the discharge in the pressure window from 2 to 3 Torr that is followed by significant raise of the electron number density and the drop of the sheaths electric field intensity. Deposition rate measurements show an important four to six times increase even for disilane mole fractions as low as 0.3 %. The deposition rate enhancement was followed by a drop of the material crystalline volume fraction but films with crystallinity above 40 % were deposited with different combinations of total gas pressure, disilane and silane molar ratios. The enhancement was partly explained by the increase of the electron impact dissociation rate of silane which rises by 40% even for 0.1% disilane mole fraction. The calculations of the gas usage, the dissociation and the deposition efficiencies show that the beneficial effect on the growth rate is not just the result of the increase of Si-containing molecules density but significant changes on the species participating to the deposition and the mechanism of the film growth are caused by the disilane addition. The enhanced participation of the highly sticking to the surface radical such as disilylene, which is the main product of disilane dissociation, was considered as the most probable reason for the significant raise of the deposition efficiency. The catalytic effect of such type of radical on the surface reactivity of species with lower sticking probability is further discussed, while it is also used to explain the restricted

  19. Near IR Scanning Angle Total Internal Reflection Raman Spectroscopy at Smooth Gold Films

    Energy Technology Data Exchange (ETDEWEB)

    McKee, Kristopher; Meyer, Matthew; Smith, Emily

    2012-04-13

    Total internal reflection (TIR) Raman and reflectivity spectra were collected for nonresonant analytes as a function of incident angle at sapphire or sapphire/smooth 50 nm gold interfaces using 785 nm excitation. For both interfaces, the Raman signal as a function of incident angle is well-modeled by the calculated interfacial mean square electric field (MSEF) relative to the incident field times the thickness of the layer being probed in the Raman measurement (D{sub RS}). The Raman scatter was reproducibly enhanced at the interface containing a gold film relative to the sapphire interface by a factor of 4.3–4.6 for aqueous pyridine or 2.2–3.7 for neat nitrobenzene, depending on the analyzed vibrational mode. The mechanism for the increased Raman signal is the enhanced MSEF at incident angles where propagating surface plasmons are excited in the metal film. The background from the TIR prism was reduced by 89–95% with the addition of the gold film, and the percent relative uncertainty in peak area was reduced from 15 to 1.7% for the 1347 cm–1 mode of nitrobenzene. Single monolayers of benzenethiol (S/N = 6.8) and 4-mercaptopyridine (S/N = 16.5) on gold films were measured by TIR Raman spectroscopy with 785 nm excitation (210 mW) without resonant enhancement in 1 min.

  20. Nucleation and growth microstructural study of ti films on 304 SS substrates

    Directory of Open Access Journals (Sweden)

    Rogério de Almeida Vieira

    2004-09-01

    Full Text Available Coating of steel surfaces with titanium films has been studied with the objective to protect them against corrosion, and to create an intermediate film for CVD diamond and TiN film deposition. In this work, the nucleation, growth mechanisms and microstructural formation of the titanium films deposited on 304 stainless steel (304 SS substrate are presented and discussed. The titanium films of variable thickness were obtained by vapour phase deposition produced by electron beam. The surfaces of these samples were observed by scanning electron microscopy. The cross sections of these samples were observed by using an atomic force microscope. The Ti film-304 SS interfaces were analyzed by X-ray diffraction. The results showed that titanium films have a columnar growth. The Ti film-304 SS interface had a residual compression stress at room temperature due to the inter-diffusion process.

  1. UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi.

    Science.gov (United States)

    Lando, Gabriela Albara; Marconatto, Letícia; Kessler, Felipe; Lopes, William; Schrank, Augusto; Vainstein, Marilene Henning; Weibel, Daniel Eduardo

    2017-07-18

    Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU) are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae , when the films were pre-treated with Ultraviolet (UV) irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), scanning electron microscopy (SEM), and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

  2. UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi

    Directory of Open Access Journals (Sweden)

    Gabriela Albara Lando

    2017-07-01

    Full Text Available Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae, when the films were pre-treated with Ultraviolet (UV irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR, scanning electron microscopy (SEM, and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

  3. Computer graphic investigation on the epitaxial growth of superconductor films

    International Nuclear Information System (INIS)

    Miyamoto, A.; Iwamoto, S.; Inui, T.; Agusa, K.

    1989-01-01

    A mechanism of the epitaxial growth the oxide superconductor films has been investigated by using the computer graphics for the combination of orthorhombic Ba 2 YCu 3 O 7-x with substrate crystals such as SrTiO 3 MgO, and ZrO 2 . The (001) plane Ba 2 YCu 3 O 7-x with substrate crystals such as SrTiO 3 , MgO, and ZrO 2 . The (001) plane of Ba 2 YCu 3 O 7-x has been shown to fit the (100) plane of SrTiO 3 , MgO, and ZrO 2 . A crystallographic fit has also been proved between the (110) plane of Ba 2 YCu 3 O 7-x and the (110) plane of SrTiO 3 . These results are consistent with the experimental data about the epitaxial growth of the Ba 2 YCu 3 O 7-x films. Furthermore, detailed investigation of atomic arrangements has indicated some differences in the ionic interaction at the superconductor-substrate interface among SrTiO 3 , MgO, and ZrO 2 substrates. As for ZrO 2 (100) plane, for examples, ionic arrangements at the oxide layer is favorable only for the interaction with Y 3+ layer of Ba 2 YCu 3 O 7-x , while the Zr-O layer of ZrO 2 can interact with both Ba-O layer and Cu-O layer of Ba 2 YCu 3 O 7-x

  4. Appraisal on Textured Grain Growth and Photoconductivity of ZnO Thin Film SILAR

    Directory of Open Access Journals (Sweden)

    Deepu Thomas

    2014-01-01

    Full Text Available ZnO thin films were prepared by successive ionic layer adsorption reaction (SILAR method. The textured grain growth along c-axis in pure ZnO thin films and doped with Sn was studied. The structural analysis of the thin films was done by X-ray diffraction and surface morphology by scanning electron microscopy. Textured grain growth of the samples was measured by comparing the peak intensities. Textured grain growth and photo current in ZnO thin films were found to be enhanced by doping with Sn. ZnO thin film having good crystallinity with preferential (002 orientation is a semiconductor with photonic properties of potential benefit to biophotonics. From energy dispersive X-ray analysis, it is inferred that oxygen vacancy creation is responsible for the enhanced textured grain growth in ZnO thin films.

  5. Epitaxial growth of atomically flat gadolinia-doped ceria thin films by pulsed laser deposition

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Pryds, Nini; Schou, Jørgen

    2011-01-01

    Epitaxial growth of Ce0.8Gd0.2O2(CGO) films on (001) TiO2-terminated SrTiO3 substrates by pulsed laser deposition was investigated using in situ reflective high energy electron diffraction. The initial film growth shows a Stransky–Krastanov growth mode. However, this three-dimensional island...... formation is replaced by a two-dimensional island nucleation during further deposition, which results in atomically smooth CGO films. The obtained high-quality CGO films may be attractive for the electrolyte of solid-oxide fuel cells operating at low temperature....

  6. Controlling thin film structure for the dewetting of catalyst nanoparticle arrays for subsequent carbon nanofiber growth

    International Nuclear Information System (INIS)

    Randolph, S J; Fowlkes, J D; Melechko, A V; Klein, K L; III, H M Meyer; Simpson, M L; Rack, P D

    2007-01-01

    Vertically aligned carbon nanofiber (CNF) growth is a catalytic chemical vapor deposition process in which structure and functionality is controlled by the plasma conditions and the properties of the catalyst nanoparticles that template the fiber growth. We have found that the resultant catalyst nanoparticle network that forms by the dewetting of a continuous catalyst thin film is dependent on the initial properties of the thin film. Here we report the ability to tailor the crystallographic texture and composition of the nickel catalyst film and subsequently the nanoparticle template by varying the rf magnetron sputter deposition conditions. After sputtering the Ni catalyst thin films, the films are heated and exposed to an ammonia dc plasma, to chemically reduce the native oxide on the films and induce dewetting of the film to form nanoparticles. Subsequent nanoparticle treatment in an acetylene plasma at high substrate temperature results in CNF growth. Evidence is presented that the texture and composition of the nickel thin film has a significant impact on the structure and composition of the formed nanoparticle, as well as the resultant CNF morphology. Nickel films with a preferred (111) or (100) texture were produced and conditions favoring interfacial silicidation reactions were identified and investigated. Both compositional and structural analysis of the films and nanoparticles indicate that the properties of the as-deposited Ni catalyst film influences the subsequent nanoparticle formation and ultimately the catalytic growth of the carbon nanofibers

  7. Zirconia thin films from aqueous precursors: Processing, microstructural development, and epitaxial growth

    International Nuclear Information System (INIS)

    Miller, K.T.

    1991-01-01

    Thin films of ZrO 2 (Y 2 O 3 ) were prepared from aqueous salt precursors by spin coating. Films were pyrolyzed to produce porous polycrystalline thin films of 5-10 nm grain size. Subsequent microstructural development depends greatly upon the nature of the substrate. Upon randomly oriented sapphire, the films initially sintered to full density; further heat treatment and grain growth causes these films to break into interconnected islands and finally isolated particles. Thermodynamic calculations predict that breakup is energetically favorable when the grain-size film-thickness ratio exceeds a critical value. Upon basal-plane-oriented sapphire, grain growth and breakup prefer the (100) oriented grains, presumably because this orientation is a special interface of low energy. The isolated, oriented grains produced by film breakup act as seeds for the growth of newly deposited material. Upon (100) cubic zirconia, true epitaxial films develop. Epitaxial growth was observed for lattice mismatches up to 1.59%. Growth proceeds from a fine epitaxial layer which is produced during the initial stages of heat treatment, consuming the porous polycrystalline material and producing a dense epitaxial thin film whose misfit is accommodated by a combination of film strain and misfit dislocations

  8. Growth Mechanism of Cluster-Assembled Surfaces: From Submonolayer to Thin-Film Regime

    Science.gov (United States)

    Borghi, Francesca; Podestà, Alessandro; Piazzoni, Claudio; Milani, Paolo

    2018-04-01

    Nanostructured films obtained by assembling preformed atomic clusters are of strategic importance for a wide variety of applications. The deposition of clusters produced in the gas phase onto a substrate offers the possibility to control and engineer the structural and functional properties of the cluster-assembled films. To date, the microscopic mechanisms underlying the growth and structuring of cluster-assembled films are poorly understood, and, in particular, the transition from the submonolayer to the thin-film regime is experimentally unexplored. Here we report the systematic characterization by atomic force microscopy of the evolution of the structural properties of cluster-assembled films deposited by supersonic cluster beam deposition. As a paradigm of nanostructured systems, we focus our attention on cluster-assembled zirconia films, investigating the influence of the building block dimensions on the growth mechanisms and roughening of the thin films, following the growth process from the early stages of the submonolayer to the thin-film regime. Our results demonstrate that the growth dynamics in the submonolayer regime determines different morphological properties of the cluster-assembled thin film. The evolution of the roughness with the number of deposited clusters reproduces the growth exponent of the ballistic deposition in the 2 +1 model from the submonolayer to the thin-film regime.

  9. Modeling of thin films growth processes in the early stage for atoms with covalent bonds

    International Nuclear Information System (INIS)

    Tupik, V A; Margolin, V I; Su, Chu Trong

    2017-01-01

    Computer simulation for obtaining thin film’s growth process at an early stage with the proposed model of atoms with isotropic and anisotropic interactions been considered. Carrying out the procedure for analyzing the problem on the basis of the program being implemented, computer simulation of thin film growth processes has been carried out on several examples. The results of computer simulation of the growth process of thin film on a given substrate and an aggregate in a vacuum condition are shown. Some characteristic distributions of the obtained structure have been carried out to evaluate the proposed adequate model and to reflect the high complexity of thin films growth process. (paper)

  10. Growth of n-alkane films on a single-crystal substrate

    DEFF Research Database (Denmark)

    Wu, Z. U.; Ehrlich, S. N.; Matthies, B.

    2001-01-01

    The structure and growth mode of alkane films (n-C/sub n/H/sub 2n+2/; n=4, 6, 7) adsorbed on a Ag(111) surface have been investigated by synchrotron X-ray scattering. New models are proposed for the butane (n=4) and hexane (n=6) monolayer and butane bilayer structures. Specular reflectivity scans...... reveal that growth of all films is preempted between two and three layers by nucleation of bulk particles oriented with a single bulk crystal plane parallel to the film. In the case of butane, the bulk particles also have a fixed azimuthal relationship with the film resulting in complete epitaxy....

  11. Growth of high quality large area MgB2 thin films by reactive evaporation

    OpenAIRE

    Moeckly, Brian H.; Ruby, Ward S.

    2006-01-01

    We report a new in-situ reactive deposition thin film growth technique for the production of MgB2 thin films which offers several advantages over all existing methods and is the first deposition method to enable the production of high-quality MgB2 films for real-world applications. We have used this growth method, which incorporates a rotating pocket heater, to deposit MgB2 films on a variety of substrates, including single-crystalline, polycrystalline, metallic, and semiconductor materials u...

  12. Atmosphere influence on in situ ion beam analysis of thin film growth

    International Nuclear Information System (INIS)

    Lin, Yuping; Krauss, A.R.; Gruen, D.M.; Chang, R.P.H.; Auciello, O.H.; Schultz, J.A.

    1994-01-01

    In situ, nondestructive surface characterization of thin-film growth processes in an environment of chemically active gas at pressures of several mTorr is required both for the understanding of growth processes in multicomponent films and layered heterostructures and for the improvement of process reproducibility and device reliability. The authors have developed a differentially pumped pulsed ion beam surface analysis system that includes ion scattering spectroscopy (ISS) and direct recoil spectroscopy (DRS), coupled to an automated ion beam sputter-deposition system (IBSD), to study film growth processes in an environment of chemically active gas, such as required for the growth of oxide, nitride, or diamond thin films. The influence of gas-phase scattering and gas-surface interactions on the ISS and DRS signal intensity and peak shape have been studied. From the intensity variation as a function of ambient gas pressure, the authors have calculated the mean free path and the scattering cross-section for a given combination of primary ion species and ambient gas. Depending on the system geometry and the combination of primary beam and background, it is shown that surface-specific data can be obtained during thin-film growth at pressures ranging from a few mtorr to approximately 1 Torr. Detailed information such as surface composition, structure, and film growth mechanism may be obtained in real-time, making ion beam analysis an ideal nondestructive, in situ probe of thin-film growth processes

  13. Growth and structure of thermally evaporated Bi{sub 2}Te{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rogacheva, E.I., E-mail: rogacheva@kpi.kharkov.ua [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine); Budnik, A.V. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine); Dobrotvorskaya, M.V.; Fedorov, A.G.; Krivonogov, S.I.; Mateychenko, P.V. [Institute for Single Crystals of NAS of Ukraine, 60 Lenin Prospect, Kharkov 61001 (Ukraine); Nashchekina, O.N.; Sipatov, A.Yu. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine)

    2016-08-01

    The growth mechanism, microstructure, and crystal structure of the polycrystalline n-Bi{sub 2}Te{sub 3} thin films with thicknesses d = 15–350 nm, prepared by thermal evaporation in vacuum onto glass substrates, were studied. Bismuth telluride with Te excess was used as the initial material for the thin film preparation. The thin film characterization was performed using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scan electron microscopy, and electron force microscopy. It was established that the chemical composition of the prepared films corresponded rather well to the starting material composition and the films did not contain any phases apart from Bi{sub 2}Te{sub 3}. It was shown that the grain size and the film roughness increased with increasing film thickness. The preferential growth direction changed from [00l] to [015] under increasing d. The X-ray photoelectron spectroscopy studies showed that the thickness of the oxidized surface layer did not exceed 1.5–2.0 nm and practically did not change in the process of aging at room temperature, which is in agreement with the results reported earlier for single crystals. The obtained data show that using simple and inexpensive method of thermal evaporation in vacuum and appropriate technological parameters, one can grow n-Bi{sub 2}Te{sub 3} thin films of a sufficiently high quality. - Highlights: • The polycrystalline n-Bi{sub 2}Te{sub 3} thin films were grown thermal evaporation onto glass. • The growth mechanism and film structure were studied by different structure methods. • The grain size and film roughness increased with increasing film thickness. • The growth direction changes from [00l] to [015] under film thickness increasing. • The oxidized layer thickness (1–2 nm) did not change under aging at room temperature.

  14. Three-dimensional growth simulation: A study of substrate oriented films

    International Nuclear Information System (INIS)

    Besnard, A; Martin, N; Carpentier, L

    2010-01-01

    Monte Carlo simulations are developed to simulate the growth of three-dimensional columnar microstructure in thin films. We are studying in particular oriented microstructure like those produced with the Glancing Angle Deposition technique (GLAD). Some geometrical characteristics of the particles flux, the organization of defect sites on the substrate surface and the atomic surface diffusion are mainly investigated in order to predict the growth processes and the resulting features of the films. This study reports on simulations of thin film growth exhibiting an oblique and zigzag columnar microstructure. Column angle evolution and density are investigated versus incidence angle α or period number n and compared with experimental measurements.

  15. Modeling of metal thin film growth: Linking angstrom-scale molecular dynamics results to micron-scale film topographies

    Science.gov (United States)

    Hansen, U.; Rodgers, S.; Jensen, K. F.

    2000-07-01

    A general method for modeling ionized physical vapor deposition is presented. As an example, the method is applied to growth of an aluminum film in the presence of an ionized argon flux. Molecular dynamics techniques are used to examine the surface adsorption, reflection, and sputter reactions taking place during ionized physical vapor deposition. We predict their relative probabilities and discuss their dependence on energy and incident angle. Subsequently, we combine the information obtained from molecular dynamics with a line of sight transport model in a two-dimensional feature, incorporating all effects of reemission and resputtering. This provides a complete growth rate model that allows inclusion of energy- and angular-dependent reaction rates. Finally, a level-set approach is used to describe the morphology of the growing film. We thus arrive at a computationally highly efficient and accurate scheme to model the growth of thin films. We demonstrate the capabilities of the model predicting the major differences on Al film topographies between conventional and ionized sputter deposition techniques studying thin film growth under ionized physical vapor deposition conditions with different Ar fluxes.

  16. Direct growth of superconducting NdFeAs(O,F) thin films by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Chihara, Masashi, E-mail: chihara@iku.xtal.nagoya-u.ac.jp [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Sumiya, Naoki; Arai, Kenta [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Ichinose, Ataru; Tsukada, Ichiro [Central Research Institute of Electric Power Industry, Yokosuka-shi, Kanagawa 240-0101 (Japan); Hatano, Takafumi; Iida, Kazumasa; Ikuta, Hiroshi [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-11-15

    Highlights: • Highly textured NdFeAs(O,F) thin films were obtained by a direct growth method. • Enhancing the migration was crucial to realize the direct growth. • The critical current density exceeded 3 MA/cm{sup 2} at self-field and 1 MA/cm{sup 2} at 9 T. • A two-dimensional growth was confirmed by the observation of surface morphology. - Abstract: We report on the growth of NdFeAs(O,F) superconducting thin films by molecular beam epitaxy without having a NdOF secondary layer that was necessary for fluorine doping in our previous studies. The key to realizing the direct growth of a superconducting film was the enhancement of migration of the raw materials on the substrate, which was accomplished by two steps. Firstly, we increased the growth temperature that improved the crystalline quality of parent NdFeAsO thin films. Secondly, the atmosphere in the chamber during the growth was improved by changing the crucible material of the Fe source cell. Highly textured NdFeAs(O,F) thin films with critical temperatures up to 50 K were obtained, and terraces were observed by atomic force microscope, indicating a two-dimensional growth. However, precipitates were also found on the surface, which suggests that enhancing further the migration is necessary for obtaining a NdFeAs(O,F) thin film with a better quality.

  17. THE ANALYSIS OF TOTAL EXPENSES AT 1000 LEI TOTAL REVENUES AND OF THE RESULT OF THE GROWTH OF THEIR EFFICIENCY

    Directory of Open Access Journals (Sweden)

    LĂPĂDUŞI MIHAELA LOREDANA

    2013-12-01

    Full Text Available act The analysis of the company’s expenses is mainly important in the management and control activity, because it highlights the way in which are used the resources (material, human, financial and the impact of their allocation on the company’s performances. The optimization of the level of costs or the their reduction, where it is possible, without affecting the quality of the products and working conditions of the activity, represent the primary objectives of the management of companies.[9] Expenses have been and will remain one of the key indicators of a company requiring continuous application of a control and monitoring mechanism because when it comes to expenses we never speak of their growth, but their reduction. This reduction is the main objective of any economic agent that will result in increasing the efficiency of the entire activity. The costs of a company reflect in cash the total consumption of material, human and financial resources used in manufacturing and selling of the products. The level, dynamics and structure of these expenses reflect synthetically the activity of industrial enterprises when using effectively the available resources. The purpose of this article is to analyze synthetically a company's expenses efficiency based on the efficiency ratio of total expenses at 1000 lei total revenues and the purpose of the article results in a set of conclusions that will highlight a number of important issues concerning the role and the importance of the efficiency of total expenses related to total revenue, as well as the result of the growth of the efficiency of total expenses.

  18. Growth of HfO{sub x} thin films by reactive molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Erwin; Kurian, Jose; Alff, Lambert [Institut fuer Materialwissenschaft, TU Darmstadt (Germany)

    2008-07-01

    Thin films of hafnium oxide were grown on single crystal r-cut and c-cut sapphire by reactive molecular beam epitaxy. The conditions for the growth of single oriented hafnium oxide thin films have been established. Hafnium oxide thin films were characterized by X-ray diffraction and optical absorption measurements. It was found that hafnium oxide thin films grown on r-cut sapphire were (00l) oriented whereas, on c-cut sapphire, hafnium oxide films showed different orientations depending on the growth temperature and oxidation conditions. The hafnium oxide films grown at higher temperature and under strong oxidation conditions yielded (001) oriented films on c-cut sapphire whereas slightly weaker oxidation condition leads to (111) oriented hafnium oxide films. The bandgap deducted from optical absorption measurement carried out on hafnium oxide films grown under optimized conditions agreed well with the values reported in literature. A range of oxygen deficient thin films of hafnium oxide were also grown on single crystal sapphire substrates in order to investigate the effect of oxygen vacancies on dielectric properties of hafnium oxide. The oxygen deficient thin films of hafnium oxide show a decrease in bandgap with increase in oxygen deficiency.

  19. Features of film growth during plasma anodizing of Al 2024/SiC metal matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Xue Wenbin [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875 (China)]. E-mail: xuewb@bnu.edu.cn

    2006-07-15

    Plasma anodizing is a novel promising process to fabricate corrosion-resistant protective films on metal matrix composites. The corrosion-resistant films were prepared by plasma anodizing on SiC reinforced aluminum matrix composite. The morphology and microstructure of films were analyzed by scanning electron microscopy. Specifically, the morphology of residual SiC reinforcement particles in the film was observed. It is found that the most SiC reinforcement particles have been molten to become silicon oxide, but a few tiny SiC particles still remain in the film close to the composite/film interface. This interface is irregular due to the hindering effect of SiC particles on the film growth. Morphology and distribution of residual SiC particles in film provide direct evidence to identify the local melt occurs in the interior of plasma anodizing film even near the composite/film interface. A model of film growth by plasma anodizing on metal matrix composites was proposed.

  20. Features of film growth during plasma anodizing of Al 2024/SiC metal matrix composite

    International Nuclear Information System (INIS)

    Xue Wenbin

    2006-01-01

    Plasma anodizing is a novel promising process to fabricate corrosion-resistant protective films on metal matrix composites. The corrosion-resistant films were prepared by plasma anodizing on SiC reinforced aluminum matrix composite. The morphology and microstructure of films were analyzed by scanning electron microscopy. Specifically, the morphology of residual SiC reinforcement particles in the film was observed. It is found that the most SiC reinforcement particles have been molten to become silicon oxide, but a few tiny SiC particles still remain in the film close to the composite/film interface. This interface is irregular due to the hindering effect of SiC particles on the film growth. Morphology and distribution of residual SiC particles in film provide direct evidence to identify the local melt occurs in the interior of plasma anodizing film even near the composite/film interface. A model of film growth by plasma anodizing on metal matrix composites was proposed

  1. Effect of different film packaging on microbial growth in minimally processed cactus pear (Opuntia ficus-indica).

    Science.gov (United States)

    Palma, A; Mangia, N P; Fadda, A; Barberis, A; Schirra, M; D'Aquino, S

    2013-01-01

    Microorganisms are natural contaminants of fresh produce and minimally processed products, and contamination arises from a number of sources, including the environment, postharvest handling and processing. Fresh-cut products are particularly susceptible to microbial contaminations because of the changes occurring in the tissues during processing. In package gas composition of modified atmosphere packaging (MAP) in combination with low storage temperatures besides reducing physiological activity of packaged produce, can also delay pathogen growth. Present study investigated on the effect of MAPs, achieved with different plastic films, on microbial growth of minimally processed cactus pear (Opuntio ficus-indica) fruit. Five different plastic materials were used for packaging the manually peeled fruit. That is: a) polypropylene film (Termoplast MY 40 micron thickness, O2 transmission rate 300 cc/m2/24h); b) polyethylene film (Bolphane BHE, 11 micron thickness, O2 transmission rate 19000 cc/m2/24h); c) polypropylene laser-perforated films (Mach Packaging) with 8, 16 or 32 100-micron holes. Total aerobic psychrophilic, mesophilic microorganisms, Enterobacteriaceae, yeast, mould populations and in-package CO2, O2 and C2H4 were determined at each storage time. Different final gas compositions, ranging from 7.8 KPa to 17.1 KPa O2, and 12.7 KPa to 2.6 KPa CO2, were achieved with MY and micro perforated films, respectively. Differences were detected in the mesophilic, Enterobacteriaceae and yeast loads, while no difference was detected in psychrophilic microorganisms. At the end of storage, microbial load in fruits sealed with MY film was significantly lower than in those sealed with BHE and micro perforated films. Furthermore, fruits packed with micro-perforated films showed the highest microbial load. This occurrence may in part be related to in-package gas composition and in part to a continuous contamination of microorganisms through micro-holes.

  2. Effects of film polarities on InN growth by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Xu, K.; Yoshikawa, A.

    2003-01-01

    Effects of the film polarity on InN growth were investigated in molecular-beam epitaxy (MBE). It was found that N-polarity InN could be grown at higher temperatures than In-polarity one. For the In-polarity films, which were grown on Ga-polar GaN template, the highest growth temperature was limited below 500 deg. C, and the surface morphology and crystal quality tended to be poor mainly because of the tolerated low growth temperature. While for the N-polarity InN films, which were grown on MBE-grown N-polar GaN, the growth temperature could be as high as 600 deg. C. The step-flow-like growth morphology was achieved for the InN films grown with N polarity at 580 deg. C. The resulting full widths of half maximum of x-ray rocking curve around InN (002) and (102) reflections were about 200-250 and 950-1100 arc sec, respectively. The photoluminescence of the InN films peaked at 0.697 eV. The recording Hall mobility of InN film grown in N polarity is 1400 cm 2 /V s with a background carrier concentration of 1.56x10 18 cm -3 at room temperature. For both-polarity films, we found N-rich condition was necessary for the stable InN growth

  3. Growth and BZO-doping of the nanostructured YBCO thin films on buffered metal substrates

    DEFF Research Database (Denmark)

    Huhtinen, H.; Irjala, M.; Paturi, P.

    2010-01-01

    The growth of the nanostructured YBa2Cu3O6+x (YBCO) films is investigated for the first time on biaxially textured NiW substrates used in coated conductor technology. The optimization process of superconducting layers is made in wide magnetic field and temperature range in order to understand...... the vortex pinning structure and mechanism in our films prepared from nanostructured material. Structural analysis shows that growth mechanism in YBCO films grown on NiW is completely different when compared to YBCO on STO. Films on NiW are much rougher, there is huge in-plane variation of YBCO crystals...... and moreover out-of-plane long range lattice ordering is greatly reduced. Magnetic measurements demonstrate that jc in films grown on NiW is higher in high magnetic fields and low temperatures. This effect is connected to the amount of pinning centres observed in films on metal substrates which are effective...

  4. Monolayer-Mediated Growth of Organic Semiconductor Films with Improved Device Performance.

    Science.gov (United States)

    Huang, Lizhen; Hu, Xiaorong; Chi, Lifeng

    2015-09-15

    Increased interest in wearable and smart electronics is driving numerous research works on organic electronics. The control of film growth and patterning is of great importance when targeting high-performance organic semiconductor devices. In this Feature Article, we summarize our recent work focusing on the growth, crystallization, and device operation of organic semiconductors intermediated by ultrathin organic films (in most cases, only a monolayer). The site-selective growth, modified crystallization and morphology, and improved device performance of organic semiconductor films are demonstrated with the help of the inducing layers, including patterned and uniform Langmuir-Blodgett monolayers, crystalline ultrathin organic films, and self-assembled polymer brush films. The introduction of the inducing layers could dramatically change the diffusion of the organic semiconductors on the surface and the interactions between the active layer with the inducing layer, leading to improved aggregation/crystallization behavior and device performance.

  5. Growth of α-sexithiophene nanostructures on C60 thin film layers

    DEFF Research Database (Denmark)

    Radziwon, Michal Jędrzej; Madsen, Morten; Balzer, Frank

    2014-01-01

    Organic molecular beam grown -sexithiophene (-6T) forms nanostructured thin films on buckminsterfullerene (C60) thin film layers. At substrate temperatures of 300K during growth a rough continuous film is observed, which develop to larger elongated islands and dendritic- as well as needle like ...... fluorescence polarimetry measurements the in-plane orientation of the crystalline sites within the needle like structures is determined. The polarimetry investigations strongly indicate that the needle like structures consist of lying molecules....

  6. Heteroepitaxial silicon film growth at 600 oC from an Al-Si eutectic melt

    International Nuclear Information System (INIS)

    Chaudhari, P.; Shim, Heejae; Wacaser, Brent A.; Reuter, Mark C.; Murray, Conal; Reuter, Kathleen B.; Jordan-Sweet, Jean; Ross, Frances M.; Guha, Supratik

    2010-01-01

    A method for growing heteroepitaxial Si films on sapphire was developed using a 6 nm thin Al layer at substrate temperature of 600 o C. Subsequently, the growth of Si nanowires was demonstrated on these films at 490 o C without breaking vacuum. We characterized the properties of the Si films by Raman scattering, X-ray diffraction and transmission electron microscopy and show that the crystal quality and dopant control are promising for photovoltaic applications.

  7. Growth of graphene films from non-gaseous carbon sources

    Science.gov (United States)

    Tour, James; Sun, Zhengzong; Yan, Zheng; Ruan, Gedeng; Peng, Zhiwei

    2015-08-04

    In various embodiments, the present disclosure provides methods of forming graphene films by: (1) depositing a non-gaseous carbon source onto a catalyst surface; (2) exposing the non-gaseous carbon source to at least one gas with a flow rate; and (3) initiating the conversion of the non-gaseous carbon source to the graphene film, where the thickness of the graphene film is controllable by the gas flow rate. Additional embodiments of the present disclosure pertain to graphene films made in accordance with the methods of the present disclosure.

  8. Morphology and growth behavior of O_2-free chemical bath deposited ZnS thin films

    International Nuclear Information System (INIS)

    Jet Meitzner, K.; Tillotson, Brock M.; Siedschlag, Amanda T.; Moore, Frederick G.; Kevan, Stephen D.; Richmond, Geraldine L.

    2015-01-01

    We investigate the role of reagent concentrations and ambient O_2 on the morphology and growth behavior of ZnS thin films grown with the chemical bath deposition method. We investigate the role of substrate on film morphology, and find significant differences between films deposited on SiO_2 versus Si. The films are also sensitive to dissolved O_2 in the bath, as it causes a layer of SiO_2 to form at the ZnS/Si interface during deposition. Degassing of solutions and an N_2 atmosphere are effective to minimize this oxidation, allowing deposition of ZnS films directly onto Si. Under these conditions, we examine film properties as they relate to reagent bath concentrations. As the reagent concentrations are decreased, both the film roughness and growth rate decrease linearly. We also observe deformation and shifting of X-ray diffraction peaks that increases with decreasing reagent concentrations. The shifts are characteristic of lattice compression (caused by the substitution of oxygen for sulfur), and the deformation is characteristic of distortion of the lattice near crystal grain interfaces (caused by tensile stress from interatomic forces between neighboring crystal grains). At the weakest concentrations, the low roughness suggests a mixed growth mode in which both clusters and individual ZnS nanocrystallites contribute to film growth. With increasing reagent concentrations, the growth mode shifts and becomes dominated by deposition of clusters. - Highlights: • We deposit ZnS thin films by chemical bath deposition in an O_2-free environment. • The O_2-free environment is effective to minimize oxidation of the Si substrate. • The dominant growth mechanism changes with reagent concentrations. • Film morphology and composition change with reagent concentrations. • X-ray diffraction reveals tensile stress between ZnS crystal grains.

  9. On the mechanism of self-deceleration of the thin oxide film growth

    CERN Document Server

    Mukhambetov, D G

    2002-01-01

    The objective of this work was to investigate the kinetics of the two-phase oxide film growth on the alpha-Fe surface at temperatures of 650-750 K. We experimentally determined that the film thickness (h)-time oxidation (tau) relationship in the range denoted above is a logarithmic function, whereas Cabrera and Mott's theory gives a square law of film growth. In our work, analytical treatment of experimental data was made based on this theory, but we propose that self-deceleration of the film growth is caused not by attenuation of the electric intensity in the film because of an increase of h but by the shielding influence of the space charge of diffusing ions and electrons in that oxide film. With that purpose in view, the Debye shielding distance for plasma substance state in the oxide film was taken into consideration. The logarithmic law of oxide film growth was derived. Estimated calculations of this law's parameters were made that quantitatively correspond with literature data. The results obtained were...

  10. Growth of fine holes in polyethyleneterephthalate film irradiated by fission fragments

    International Nuclear Information System (INIS)

    Komaki, Y.; Tsujimura, S.

    1975-01-01

    Growth of fine holes by chemical etching in polyethyleneterephthalate films exposed to fission fragments were followed by measuring gas flow through films. The etching rate along tracks and the radial etching rate were determined at hole diameters of 100--3000 A and hole densities of 10 6 --10 8 /cm 2

  11. Growth-temperature-dependent optical and acetone detection properties of ZnO thin films

    International Nuclear Information System (INIS)

    Shewale, P. S.; Yu, Y. S.

    2015-01-01

    Zinc oxide (ZnO) thin films were prepared onto glass substrates at moderately low growth temperature by two-stage spray pyrolysis technique. The effects of growth temperature on structural, optical and acetone detection properties were investigated with X-ray diffractometry, a UV–visible spectrophotometer, photoluminescence (PL) spectroscopy and a homemade gas sensor testing unit, respectively. All the films are polycrystalline with a hexagonal wurtzite phase and exhibit a preferential orientation along [002] direction. The film crystallinity is gradually enhanced with an increase in growth temperature. The optical measurements show that all the films are physically highly transparent with a transmittance greater than 82% in the visible range. The band gap of the film is observed to exhibit a slight red shift with an increasing growth temperature. The PL studies on the films show UV/violet PL band at ∼ 395 nm. Among all the films investigated, the film deposited at 250 °C demonstrates a maximum sensitivity of 13% towards 20 ppm of acetone vapors at 300 °C operating temperature. (paper)

  12. Total factor productivity (TFP) growth agriculture in pakistan: trends in different time horizons

    International Nuclear Information System (INIS)

    Ali, A.; Mushtaq, K.; Ashfaq, M.

    2008-01-01

    The present study estimated total factor productivity (TFP) growth of agriculture sector of Pakistan for the period 1971-2006 by employing Tornqvist-Theil (T-T) index number methodology. Most of the conventional inputs were used in constructing the input index. The output index includes major crops, minor crops, important fruits and vegetables and four categories of livestock products. The study estimated TFP growth rates for different decades. The results showed that TFP growth rate was lowest during the decade of 70s (0.96 percent) and highest during the last six years of the study period (2.86 percent). The decade of 80s and 90s registered TFP growth rate of 2.24 percent and 2.46 percent, respectively. The results also explained that TFP growth contributed about 33 percent to total agricultural output growth during the decade of 70s and this contribution increased up to 83 percent during the last six years of the study period. The contribution of TFP growth to total agricultural output growth was 53 and 81 percent during the decades of 80s and 90s, respectively. The study observed that macro level government policies, institutional factors and weather conditions are the major key factors that influenced TFP growth. (author)

  13. Effects of thermal treatment on the anodic growth of tungsten oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Y., E-mail: yqchai85@gmail.com; Tam, C.W.; Beh, K.P.; Yam, F.K.; Hassan, Z.

    2015-08-03

    This work reports the investigation of the effects of thermal treatment on anodic growth tungsten oxide (WO{sub 3}). The increase of the thermal treatment temperature above 400 °C significantly influences WO{sub 3} film where high porosity structure reduces to more compact film. As-grown film is amorphous, which transforms to monoclinic/orthorhombic phase upon annealing at 300–600 °C. With the reducing of porous structure, preferential growth of (002) plane shifts to (020) plane at 600 °C with more than twentyfold increase of peak's intensity compared to the film annealed at 500 °C. Films annealed at low thermal treatment show better ion intercalation and reversibility during electrochemical measurements; however, it has larger optical band gap. Photoelectrochemical measurement reveals that film annealed at 400 °C exhibits the best photocatalytic performance among the films annealed at 300–600 °C. - Highlights: • Porosity of the WO{sub 3} reduces as annealing temperature increases above 400 °C. • As-grown film is amorphous which transforms to monoclinic/orthorhombic upon annealing. • As-grown film shows better ion intercalation in electrochemical process. • Optical band gap of WO{sub 3} reduces as the annealing temperature increases. • Film annealed at 400 °C exhibits best photocatalytic performance.

  14. Growth and characterization of ultrathin epitaxial MnO film on Ag(001)

    Science.gov (United States)

    Kundu, Asish K.; Menon, Krishnakumar S. R.

    2016-07-01

    We present here a comprehensive growth procedure to obtain a well-ordered MnO(001) ultrathin film on Ag(001) substrate. Depending upon the oxygen partial pressure during the growth, different phases of manganese oxide have been detected by Low Energy Electron Diffraction (LEED) and X-ray Photoelectron Spectroscopic (XPS) studies. A modified growth scheme has been adopted to get well-ordered and stoichiometric MnO(001) ultrathin film. The detailed growth mechanism of epitaxial MnO film on Ag(001) has been studied step by step, using LEED and XPS techniques. Observation of sharp (1 × 1) LEED pattern with a low inelastic background, corresponds to a long-range atomic order with low defect densities indicating the high structural quality of the film. The Mn 2p and Mn 3s core-level spectra confirm the oxidation state as well as the stoichiometry of the grown MnO films. Apart from the growth optimization, the evolution of strain relaxation of the MnO(001) film with film thickness has been explored.

  15. Factors affecting the growth of the Malawian film industry | Magalasi ...

    African Journals Online (AJOL)

    Journal of Development and Communication Studies ... This article attempts to ask some of the most basic questions about the practice of film making in Malawi on who, what, and how films have been created, tracing the history of cinema from the British Colonial practice, through Kamuzu Banda's reign to the present.

  16. Effect of power on the growth of nanocrystalline silicon films

    International Nuclear Information System (INIS)

    Kumar, Sushil; Dixit, P N; Rauthan, C M S; Parashar, A; Gope, Jhuma

    2008-01-01

    Nanocrystalline silicon thin films were grown using a gaseous mixture of silane, hydrogen and argon in a plasma-enhanced chemical vapor deposition system. These films were deposited away from the conventional low power regime normally used for the deposition of device quality hydrogenated amorphous silicon films. It was observed that, with the increase of applied power, there is a change in nanocrystalline phases which were embedded in the amorphous matrix of silicon. Atomic force microscopy micrographs show that these films contain nanocrystallite of 20-100 nm size. Laser Raman and photoluminescence peaks have been observed at 514 cm -1 and 2.18 eV, respectively, and particle sizes were estimated using the same as 8.24 nm and 3.26 nm, respectively. It has also been observed that nanocrystallites in these films enhanced the optical bandgap and electrical conductivity

  17. Effect of power on the growth of nanocrystalline silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sushil; Dixit, P N; Rauthan, C M S; Parashar, A; Gope, Jhuma [Plasma Processed Materials Group, National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110 012 (India)], E-mail: skumar@mail.nplindia.ernet.in

    2008-08-20

    Nanocrystalline silicon thin films were grown using a gaseous mixture of silane, hydrogen and argon in a plasma-enhanced chemical vapor deposition system. These films were deposited away from the conventional low power regime normally used for the deposition of device quality hydrogenated amorphous silicon films. It was observed that, with the increase of applied power, there is a change in nanocrystalline phases which were embedded in the amorphous matrix of silicon. Atomic force microscopy micrographs show that these films contain nanocrystallite of 20-100 nm size. Laser Raman and photoluminescence peaks have been observed at 514 cm{sup -1} and 2.18 eV, respectively, and particle sizes were estimated using the same as 8.24 nm and 3.26 nm, respectively. It has also been observed that nanocrystallites in these films enhanced the optical bandgap and electrical conductivity.

  18. Growth of nanocomposite films from accelerated C60 ions

    International Nuclear Information System (INIS)

    Pukha, V E; Zubarev, E N; Drozdov, A N; Pugachov, A T; Jeong, S H; Nam, S C

    2012-01-01

    A beam of accelerated C 60 ions is used to deposit superhard (∼50 GPa) carbon films that exhibit high index plasticity (∼0.13-0.14) and high conductivity (up to 3000 S m -1 ). Transmission electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy are subsequently used to study the microstructure and bond character of the deposited films. The films consist of textured graphite nanocrystals and diamond-like amorphous carbon (DLC). The graphene plane of the nanocrystals is aligned perpendicular to the film surface. It is shown that sp 2 bonds dominate in the films. The percentage of sp 3 bonds depends on the ion energy and the substrate temperature, and does not exceed 40%. The obtained results suggest that a new nanocomposite material consisting of oriented graphite nanocrystals reinforced by a DLC matrix is synthesized. A simple model is proposed to correlate the excellent mechanical properties with the observed structure. (paper)

  19. Big-data reflection high energy electron diffraction analysis for understanding epitaxial film growth processes.

    Science.gov (United States)

    Vasudevan, Rama K; Tselev, Alexander; Baddorf, Arthur P; Kalinin, Sergei V

    2014-10-28

    Reflection high energy electron diffraction (RHEED) has by now become a standard tool for in situ monitoring of film growth by pulsed laser deposition and molecular beam epitaxy. Yet despite the widespread adoption and wealth of information in RHEED images, most applications are limited to observing intensity oscillations of the specular spot, and much additional information on growth is discarded. With ease of data acquisition and increased computation speeds, statistical methods to rapidly mine the data set are now feasible. Here, we develop such an approach to the analysis of the fundamental growth processes through multivariate statistical analysis of a RHEED image sequence. This approach is illustrated for growth of La(x)Ca(1-x)MnO(3) films grown on etched (001) SrTiO(3) substrates, but is universal. The multivariate methods including principal component analysis and k-means clustering provide insight into the relevant behaviors, the timing and nature of a disordered to ordered growth change, and highlight statistically significant patterns. Fourier analysis yields the harmonic components of the signal and allows separation of the relevant components and baselines, isolating the asymmetric nature of the step density function and the transmission spots from the imperfect layer-by-layer (LBL) growth. These studies show the promise of big data approaches to obtaining more insight into film properties during and after epitaxial film growth. Furthermore, these studies open the pathway to use forward prediction methods to potentially allow significantly more control over growth process and hence final film quality.

  20. Growth of (100)-highly textured BaBiO{sub 3} thin films on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ferreyra, C. [GIyA and INN, CNEA, Av. Gral Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Departamento de Física, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1, Ciudad Universitaria, Buenos Aires (Argentina); Marchini, F. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Departamento de Química Inorgánica, Analítica y Química-Física, INQUIMAE-CONICET, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, Buenos Aires (Argentina); Granell, P. [INTI, CMNB, Av. Gral Paz 5445, B1650KNA San Martín, Buenos Aires (Argentina); Golmar, F. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); INTI, CMNB, Av. Gral Paz 5445, B1650KNA San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología, UNSAM, Campus Miguelete, 1650 San Martín, Buenos Aires (Argentina); Albornoz, C. [GIyA and INN, CNEA, Av. Gral Paz 1499, 1650 San Martín, Buenos Aires (Argentina); and others

    2016-08-01

    We report on the growth and characterization of non-epitaxial but (100)-highly textured BaBiO{sub 3} thin films on silicon substrates. We have found the deposition conditions that optimize the texture, and show that the textured growth is favoured by the formation of a BaO layer at the first growth stages. X-ray diffraction Φ-scans, together with the observation that the same textured growth is found on films grown on Pt and SiO{sub 2} buffered Si, demonstrate the absence of epitaxy. Finally, we have shown that our (100)-oriented BaBiO{sub 3} films can be used as suitable buffers for the growth of textured heterostructures on silicon, which could facilitate the integration of potential devices with standard electronics. - Highlights: • BaBiO{sub 3} thin films were grown on Si substrates and characterized. • Films prepared using optimized conditions are highly textured in the (100) direction. • The absence of in-plane texture was demonstrated by X-ray diffraction. • Our films are suitable buffers for the growth of (100)-textured oxide heterostructures.

  1. Chemical structural analysis of diamondlike carbon films: I. Surface growth model

    Science.gov (United States)

    Takabayashi, Susumu; Ješko, Radek; Shinohara, Masanori; Hayashi, Hiroyuki; Sugimoto, Rintaro; Ogawa, Shuichi; Takakuwa, Yuji

    2018-02-01

    The surface growth mechanisms of diamondlike carbon (DLC) films has been clarified. DLC films were synthesized in atmospheres with a fixed methane-to-argon ratio at different temperatures up to 700 °C by the photoemission-assisted glow discharge of photoemission-assisted plasma-enhanced chemical vapor deposition. The electrical resistivity of the films decreased logarithmically as the synthesis temperature was increased. Conversely, the dielectric constant of the films increased and became divergent at high temperature. However, the very high electrical resistivity of the film synthesized at 150 °C was retained even after post-annealing treatments at temperatures up to 500 °C, and divergence of the dielectric constant was not observed. Such films exhibited excellent thermal stability and retained large amounts of hydrogen, even after post-annealing treatments. These results suggest that numerous hydrogen atoms were incorporated into the DLC films during synthesis at low temperatures. Hydrogen atoms terminate carbon dangling bonds in the films to restrict π-conjugated growth. During synthesis at high temperature, hydrogen was desorbed from the interior of the growing films and π-conjugated conductive films were formed. Moreover, hydrogen radicals were chemisorbed by carbon atoms at the growing DLC surface, leading to removal of carbon atoms from the surface as methane gas. The methane molecules decomposed into hydrocarbons and hydrogen radicals through the attack of electrons above the surface. Hydrogen radicals contributed to the etching reaction cycle of the film; the hydrocarbon radicals were polymerized by reacting with other radicals and the methane source. The polymer radicals remained above the film, preventing the supply of the methane source and disrupting the action of argon ions. At high temperatures, the resultant DLC films were rough and thin.

  2. A method for thickness determination of thin films of amalgamable metals by total-reflection X-ray fluorescence

    International Nuclear Information System (INIS)

    Bennun, L.; Greaves, E.D.; Barros, H.; Diaz-Valdes, J.

    2009-01-01

    A method for thickness determination of thin amalgamable metallic films by total-reflection X-ray fluorescence (TXRF) is presented. The peak's intensity in TXRF spectra are directly related to the surface density of the sample, i.e. to its thickness in a homogeneous film. Performing a traditional TXRF analysis on a thin film of an amalgamated metal, and determining the relative peak intensity of a specific metal line, the layer thickness can be precisely obtained. In the case of gold thickness determination, mercury and gold peaks overlap, hence we have developed a general data processing scheme to achieve the most precise results.

  3. The study of thin film growth by using Monte Carlo method

    International Nuclear Information System (INIS)

    Tandogan, M.; Aktas, S.

    2010-01-01

    Thin film growth was studied by using Monte Carlo simulation method. Three basic models were used in this study. Model A, the gas particles used for the formation of film were under no external effects until they stick on the surface or to another particle which already stickled on the surface to form the film. Model B, gases were drifted towards the surface by an external agent. Model C, where the gas particles in the closed container were always distributed uniformly throughout the container while they are in gas state. The simulations revealed the fact that for an ideal thin film growth Model C gave the best result to prepare a thin film while a thicker but a better quality could be obtained by Model B.

  4. Growth and Analysis of Highly Oriented (11n) BCSCO Films for Device Research

    Science.gov (United States)

    Raina, K. K.; Pandey, R. K.

    1995-01-01

    Films of BCSCO superconductor of the type Bi2CaSr2Cu2O(x), have been grown by liquid phase epitaxy method (LPE), using a partially closed growth chamber. The films were grown on (001) and (110) NdGaO3 substrates by slow cooling process in an optimized temperature range below the peritectic melting point (880 C) of Bi2CaSr2Cu2O8. Optimization of parameters, such as seed rotation, soak of initial growth temperature and growth period results in the formation of 2122 phase BCSCO films. The films grown at rotation rates of less than 30 and more than 70 rpm are observed to be associated with the second phase of Sr-Ca-Cu-O system. Higher growth temperatures (greater than 860 C) also encourage to the formation of this phase. XRD measurements show that the films grown on (110) NdGaO3 have a preferred (11n)-orientation. It is pertinent to mention here that in our earlier results published elsewhere we obtained c-axis oriented Bi2CaSr2Cu2O8 phase films on (001) NdGaO3 substrate. Critical current density is found to be higher for the films grown on (110) than (001) NdGaO3 substrate orientation. The best values, zero resistance (T(sab co)) and critical current density obtained are 87 K and 10(exp 5) A/sq cm respectively.

  5. Growth and analysis of highly oriented (11n) BCSCO films for device research

    International Nuclear Information System (INIS)

    Raina, K.K.; Pandey, R.K.

    1994-01-01

    Films of BCSCO superconductor of the type Bi 2 CaSr 2 Cu 2 O x have been grown by liquid phase epitaxy method (LPE), using a partially closed growth chamber. The films were grown on (001) and (110) NdGaO 3 substrates by slow cooling process in an optimized temperature range below the peritectic melting point (880 degrees C) of Bi 2 CaSr 2 Cu 2 O 8 . Optimization of parameters, such as seed rotation, soak of initial growth temperature and growth period results in the formation of 2122 phase BCSCO films. The films grown at rotation rates of less than 30 and more than 70 rpm are observed to be associated with the second phase of Sr-Ca-Cu-O system. Higher growth temperatures (>860 degrees C) also encourage to the formation of this phase. XRD measurements show that the films grown on (110) NdGaO 3 have a preferred (11n)-orientation. It is pertinent to mention here that in our earlier results published elsewhere we obtained c-axis oriented Bi 2 CaSr 2 Cu 2 O 8 phase films on (001) NdGaO 3 substrate. Critical current density is found to be higher for the films grown on (110) than (001) NdGaO 3 substrate orientation. The best values of zero resistance (T co ) and critical current density obtained are 87 K and 10 5 A/cm 2 , respectively

  6. Growth dynamics of reactive-sputtering-deposited AlN films

    International Nuclear Information System (INIS)

    Auger, M.A.; Vazquez, L.; Sanchez, O.; Jergel, M.; Cuerno, R.; Castro, M.

    2005-01-01

    We have studied the surface kinetic roughening of AlN films grown on Si(100) substrates by dc reactive sputtering within the framework of the dynamic scaling theory. Films deposited under the same experimental conditions for different growth times were analyzed by atomic force microscopy and x-ray diffraction. The AlN films display a (002) preferred orientation. We have found two growth regimes with a crossover time of 36 min. In the first regime, the growth dynamics is unstable and the films present two types of textured domains, well textured and randomly oriented, respectively. In contrast, in the second regime the films are homogeneous and well textured, leading to a relative stabilization of the surface roughness characterized by a growth exponent β=0.37±0.03. In this regime a superrough scaling behavior is found with the following exponents: (i) Global exponents: roughness exponent α=1.2±0.2 and β=0.37±0.03 and coarsening exponent 1/z=0.32±0.05; (ii) local exponents: α loc =1, β loc =0.32±0.01. The differences between the growth modes are found to be related to the different main growth mechanisms dominating their growth dynamics: sticking anisotropy and shadowing, respectively

  7. Growth and Etch Rate Study of Low Temperature Anodic Silicon Dioxide Thin Films

    Directory of Open Access Journals (Sweden)

    Akarapu Ashok

    2014-01-01

    Full Text Available Silicon dioxide (SiO2 thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs and microelectromechanical systems (MEMS. Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics.

  8. Monolithic growth of partly cured polydimethylsiloxane thin film layers

    DEFF Research Database (Denmark)

    Yu, Liyun; Skov, Anne Ladegaard

    2014-01-01

    at different curing times. The monolithic films are investigated by rheology, scanning electron microscope, mechanical testing, dielectric relaxation spectroscopy, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology, mechanical and dielectric properties, as well...... to enable interlayer crosslinking reactions either by application of an adhesion promoter or by ensuring that there are reactive, complementary sites available on the two surfaces. Polydimethylsiloxane (PDMS) is a widely used polymer for DEAPs. In this work, two-layered PDMS films are adhered together...... as thermal stabilities of the bilayer elastomer films are observed to change with the curing time of the monolayers before lamination. The objective of this work is to create adhesion of two layers without destroying the original viscoelastic properties of the PDMS films, and hence enable, for example...

  9. Adsorption-controlled growth of BiMnO3 films by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Lee, J. H.; Ke, X.; Misra, R.; Schiffer, P.; Ihlefeld, J. F.; Mei, Z. G.; Liu, Z. K.; Xu, X. S.; Musfeldt, J. L.; Heeg, T.; Schlom, D. G.; Roeckerath, M.; Schubert, J.

    2010-01-01

    We have developed the means to grow BiMnO 3 thin films with unparalleled structural perfection by reactive molecular-beam epitaxy and determined its band gap. Film growth occurs in an adsorption-controlled growth regime. Within this growth window bounded by oxygen pressure and substrate temperature at a fixed bismuth overpressure, single-phase films of the metastable perovskite BiMnO 3 may be grown by epitaxial stabilization. X-ray diffraction reveals phase-pure and epitaxial films with ω rocking curve full width at half maximum values as narrow as 11 arc sec (0.003 deg. ). Optical absorption measurements reveal that BiMnO 3 has a direct band gap of 1.1±0.1 eV.

  10. Co-depositing Sn controls the growth of Al films as surfactant

    International Nuclear Information System (INIS)

    Barna, P. B.; Kovacs, A.; Misjak, F.; Eisenmenger-Sittner, C.; Bangert, H.; Tomastik, C.

    2002-01-01

    The present study investigates the influence of co-deposited Sn on the atomic processes involved in the structure evolution of vapour-deposited Al films. The films were prepared in HV by thermal evaporation from W sources at 1600 C substrate temperature either on Si wafers covered by a thermally grown oxide or on air cleaved mica. By applying the half-shadow technique, pure and Sn-doped Al films could be deposited simultaneously. The samples were investigated by AFM, scanning AES, X-TEM as well as by X-ray diffraction methods. The grain growth of Al is promoted by Sn in all stages of the film formation. Scanning AES measurements prove the existence of a wetting Sn layer both on the surface of Al islands and on the surface of the continuos Al layer. Excess Sn forms islands on the growth surface. The surface of pure Al layers exhibits grain boundary grooves and bunches of growth steps around terraces, while that of the Sn doped layers is more rounded. The substrate-film interface was covered by a thin Sn layer. AES measurements also prove the presence of Sn on the growth surface of Al films even after termination of Sn addition. Results of these experiments indicate that during co-deposition of Al and Sn the impinging Al atoms penetrate the wetting layer and are incorporated into the already existing Al crystals. A model has been developed for describing the growth of Al crystals in the presence Sn. (Authors)

  11. Centimetre-scale micropore alignment in oriented polycrystalline metal-organic framework films via heteroepitaxial growth.

    Science.gov (United States)

    Falcaro, Paolo; Okada, Kenji; Hara, Takaaki; Ikigaki, Ken; Tokudome, Yasuaki; Thornton, Aaron W; Hill, Anita J; Williams, Timothy; Doonan, Christian; Takahashi, Masahide

    2017-03-01

    The fabrication of oriented, crystalline films of metal-organic frameworks (MOFs) is a critical step toward their application to advanced technologies such as optics, microelectronics, microfluidics and sensing. However, the direct synthesis of MOF films with controlled crystalline orientation remains a significant challenge. Here we report a one-step approach, carried out under mild conditions, that exploits heteroepitaxial growth for the rapid fabrication of oriented polycrystalline MOF films on the centimetre scale. Our methodology employs crystalline copper hydroxide as a substrate and yields MOF films with oriented pore channels on scales that primarily depend on the dimensions of the substrate. To demonstrate that an anisotropic crystalline morphology can translate to a functional property, we assembled a centimetre-scale MOF film in the presence of a dye and showed that the optical response could be switched 'ON' or 'OFF' by simply rotating the film.

  12. Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

    Science.gov (United States)

    An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

    2015-02-01

    Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

  13. Growth and quantum transport properties of vertical Bi2Se3 nanoplate films on Si substrates.

    Science.gov (United States)

    Li, M Z; Wang, Z H; Yang, L; Pan, D S; Li, Da; Gao, Xuan; Zhang, Zhi-Dong

    2018-05-14

    Controlling the growth direction (planar vs. vertical) and surface-to-bulk ratio can lead to lots of unique properties for two-dimensional (2D) layered materials. We report a simple method to fabricate continuous films of vertical Bi2Se3 nanoplates on Si substrate and investigate the quantum transport properties of such films. In contrast to (001) oriented planar Bi2Se3 nanoplate film, vertical Bi2Se3 nanoplate films are enclosed by (015) facets, which possess high surface-to-bulk ratio that can enhance the quantum transport property of topological surface states. And by controlling the compactness of vertical Bi2Se3 nanoplates, we realized an effective tuning of the weak antilocalization (WAL) effect from topological surface states in Bi2Se3 films. Our work paves a way for exploring the unique transport properties of this unconventional structure topological insulator film. © 2018 IOP Publishing Ltd.

  14. Growth-related magnetic and physical structures in CMR films

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, M.E.; Brown, G.W.; Hundley, M.F. [and others

    1997-09-01

    Scanning tunneling microscopy (STM), atomic force microscopy (AFM), and magnetic force microscopy (MFM) have proven to be powerful tools for revealing property-sensitive structures in magnetic materials. With the renewed interest in perovskite films as materials for read-heads in high density magnetic data storage, the same challenges faced by high temperature superconductor (HTS) film fabrication are repeated for these materials. To begin addressing these challenges, we used vapor phase epitaxy to fabricate La (Sr, Ca,) based manganate films on single crystal perovskite substrates under different conditions and characterized them with scanning probe microscopies, x-ray diffraction, and temperature-dependent magnetization and resistivity measurements (M(T) and {rho}(T)). The as-grown films were polygranular with grain sizes increasing with increasing temperature (T). The post-deposition annealed films consisted of coalesced layers with improved transport properties. The room temperature magnetic structure of the Sr-based films appeared to be related to defects and/or strain.

  15. Growth, characterization, and device development in monocrystalline diamond films

    Science.gov (United States)

    Davis, Robert F.

    1991-12-01

    The nucleation of diamond grains on an unscratched silicon wafer is enhanced by four order of magnitude relative to scratched substrates by using negative bias enhanced microwave plasma CVD in a 2 percent methane/hydrogen plasma for an initial period. In vacuo surface analysis has revealed that the actual nucleation occurs on the amorphous C coating present on the thin SiC layer which forms as the product of the initial reaction with the Si surface. It is believed that the C forms critical clusters which are favorable for diamond nucleation. Similar enhancement was observed together with the occurrence of textured diamond films in the use of bias pretreatment of cubic Beta SiC substrates. Approximately 50 percent of the initial diamond nuclei were aligned with the SiC substrate. In contrast, the use of the biasing pretreatment for one hour on polycrystalline substrates resulted in only about 7 percent coverage with diamond particles. Numerous techniques have been used to analyze the nucleation and growth phenomena, especially micro Raman and scanning tunneling microscopy. The latter technique has shown that the morphology of doped and undoped diamond nuclei are similar, as well as the fact that significant concentrations of vacancy related defects are present. In device related-studies, UV-photoemission studies have shown that TiC occurs at the Ti-diamond (100) interface after a 400 C anneal. The Schottky barrier height from this metal on p-type diamond was determined to be 1.0 eV. Indications of negative electron affinity (NEA) was observed and attributed to emission of electrons that are quasi-thermalized to the bottom of the conduction band. A disordered surface removes the NEA. The microwave performance of p-type (beta-doped) diamond MESFET's at 10 GHz has been further investigated. Elevated temperatures may be necessary to obtain sufficient free charge densities in the conducting channel but this will result in degraded device performance. Each of these

  16. Investigating the crystal growth behavior of biodegradable polymer blend thin films using in situ atomic force microscopy

    CSIR Research Space (South Africa)

    Malwela, T

    2014-01-01

    Full Text Available This article reports the crystal growth behavior of biodegradable polylactide (PLA)/poly[(butylene succinate)-co-adipate] (PBSA) blend thin films using atomic force microscopy (AFM). Currently, polymer thin films have received increased research...

  17. Room temperature growth of nanocrystalline anatase TiO2 thin films by dc magnetron sputtering

    International Nuclear Information System (INIS)

    Singh, Preetam; Kaur, Davinder

    2010-01-01

    We report, the structural and optical properties of nanocrystalline anatase TiO 2 thin films grown on glass substrate by dc magnetron sputtering at room temperature. The influence of sputtering power and pressure over crystallinity and surface morphology of the films were investigated. It was observed that increase in sputtering power activates the TiO 2 film growth from relative lower surface free energy to higher surface free energy. XRD pattern revealed the change in preferred orientation from (1 0 1) to (0 0 4) with increase in sputtering power, which is accounted for different surface energy associated with different planes. Microstructure of the films also changes from cauliflower type to columnar type structures with increase in sputtering power. FESEM images of films grown at low pressure and low sputtering power showed typical cauliflower like structure. The optical measurement revealed the systematic variation of the optical constants with deposition parameters. The films are highly transparent with transmission higher than 90% with sharp ultraviolet cut off. The transmittance of these films was found to be influenced by the surface roughness and film thickness. The optical band gap was found to decrease with increase in the sputtering power and pressure. The refractive index of the films was found to vary in the range of 2.50-2.24 with increase in sputtering pressure or sputtering power, resulting in the possibility of producing TiO 2 films for device applications with different refractive index, by changing the deposition parameters.

  18. Molecular beam epitaxy growth of InSb1−xBix thin films

    DEFF Research Database (Denmark)

    Song, Yuxin; Wang, Shumin; Saha Roy, Ivy

    2013-01-01

    Molecular beam epitaxy growth for InSb1−xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology are stu...

  19. Morphological analysis of co-evaporated blend films based on initial growth for organic photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Yosei, E-mail: yosei.shibata@aist.go.jp [Research Center for Photovoltaic Technologies, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Taima, Tetsuya [Research Center for Photovoltaic Technologies, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Zhou, Ying; Ohashi, Noboru; Kono, Takahiro [Research Center for Photovoltaic Technologies, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Yoshida, Yuji, E-mail: yuji.yoshida@aist.go.jp [Research Center for Photovoltaic Technologies, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

    2015-11-15

    Graphical abstract: - Highlights: • Initial growth mode of co-evaporated films was observed. • Balanced crystal growth leads to improvement of photovoltaic performance. • Crystal growth of fullerene during co-evaporation process was restricted. • The power conversion efficiency of 3% was obtained without electron blocking layer. - Abstract: Bulk heterojunction structures composed of electron donor and acceptor molecules for application in high-performance organic photovoltaics studied. To fabricate these structures, the co-evaporation method in vacuum is commonly applied; however, the details of the crystal growth process during co-evaporation have not yet been established. Here, we focused on structural analysis of blend films composed of phthalocyanine and fullerene based on initial growth stage. Similar crystal growth behavior to that typically observed in single-component molecules is obtained for the films. These results suggest that the competitive crystal growth between donors and acceptors occurs during co-evaporation process. The balance of thin film growth among donor and acceptor molecules can be related to improved photovoltaic performance. The homogeneous blend structure leads to improvement of the power conversion efficiency from 1.2% to 3.0%.

  20. Growth of magnetite films by a hydrogel method

    Energy Technology Data Exchange (ETDEWEB)

    Velásquez, A.A., E-mail: avelas26@eafit.edu.edu.co [Grupo de Electromagnetismo Aplicado, Universidad EAFIT, A.A. 3300, Medellín (Colombia); Marín, C.C. [Grupo de Electromagnetismo Aplicado, Universidad EAFIT, A.A. 3300, Medellín (Colombia); Urquijo, J.P. [Grupo de Estado Sólido, Instituto de Física, Universidad de Antioquia, A.A. 1226, Medellín (Colombia)

    2017-06-15

    Magnetite (Fe{sub 3}O{sub 4}) films were grown on glass substrates by formation and condensation of complex of iron oxides in an agarose hydrogel. The obtained films were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Room Temperature Mössbauer Spectroscopy (TMS), Vibrating Sample Magnetometry (VSM), Atomic Force Microscopy (AFM) and Voltage vs. Current measurements by the four-point method. FTIR and TGA measurements showed that some polymer chains of agarose remain linked to the surface of the magnetic particles of the films after heat treatment. SEM measurements showed that the films are composed by quasi spherical particles with sizes around 55 nm. Mössbauer spectroscopy measurements showed two sextets with broaden lines, which were assigned to magnetite with a distributed particle size, and two doublets, which were assigned to superparamagnetic phases of magnetite. For the specific dimensions of the films prepared, measurements of Voltage vs. Current showed an ohmic behavior for currents between 0 and 200 nA, with a resistance of 355 kΩ.

  1. Growth of magnetite films by a hydrogel method

    International Nuclear Information System (INIS)

    Velásquez, A.A.; Marín, C.C.; Urquijo, J.P.

    2017-01-01

    Magnetite (Fe 3 O 4 ) films were grown on glass substrates by formation and condensation of complex of iron oxides in an agarose hydrogel. The obtained films were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Room Temperature Mössbauer Spectroscopy (TMS), Vibrating Sample Magnetometry (VSM), Atomic Force Microscopy (AFM) and Voltage vs. Current measurements by the four-point method. FTIR and TGA measurements showed that some polymer chains of agarose remain linked to the surface of the magnetic particles of the films after heat treatment. SEM measurements showed that the films are composed by quasi spherical particles with sizes around 55 nm. Mössbauer spectroscopy measurements showed two sextets with broaden lines, which were assigned to magnetite with a distributed particle size, and two doublets, which were assigned to superparamagnetic phases of magnetite. For the specific dimensions of the films prepared, measurements of Voltage vs. Current showed an ohmic behavior for currents between 0 and 200 nA, with a resistance of 355 kΩ.

  2. Molecular dynamics simulation about porous thin-film growth in secondary deposition

    International Nuclear Information System (INIS)

    Chen Huawei; Tieu, A. Kiet; Liu Qiang; Hagiwara, Ichiro; Lu Cheng

    2007-01-01

    The thin film growth has been confirmed to be assembled by an enormous number of clusters in experiments of CVD. Sequence of clusters' depositions proceeds to form the thin film at short time as gas fluids through surface of substrate. In order to grow condensed thin film using series of cluster deposition, the effect of initial velocity, substrate temperature and density of clusters on property of deposited thin film, especially appearance of nanoscale pores inside thin film must be investigated. In this simulation, three different cluster sizes of 203, 653, 1563 atoms with different velocities (0, 10, 100, 1000 and 3000 m/s) were deposited on a Cu(0 0 1) substrate whose temperatures were set between 300 and 1000 K. Four clusters and one cluster were used in primary deposition and secondary deposition, respectively. We have clarified that adhesion between clusters and substrate is greatly influenced by initial velocity. As a result, the exfoliation pattern of deposited thin film is dependent on initial velocity and different between them. One borderline dividing whole region into porous region and nonporous region are obtained to show the effect of growth conditions on appearance of nanoscale pores inside thin film. Moreover, we have also shown that the likelihood of porous thin film is dependent on the point of impact of a cluster relative to previously deposited clusters

  3. Molecular dynamics simulation about porous thin-film growth in secondary deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen Huawei [School of Mechanical Engineering and Automation, Beihang University, No. 37 Xuyuan Road, Haidian District, Beijing (China) and Mechanical Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, NSW 2522 (Australia)]. E-mail: chen_hua_wei@yahoo.com; Tieu, A. Kiet [Mechanical Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, NSW 2522 (Australia); Liu Qiang [School of Mechanical Engineering and Automation, Beihang University, No. 37 Xuyuan Road, Haidian District, Beijing (China); Hagiwara, Ichiro [Department of Mechanical Sciences and Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo (Japan); Lu Cheng [Mechanical Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, NSW 2522 (Australia)

    2007-07-15

    The thin film growth has been confirmed to be assembled by an enormous number of clusters in experiments of CVD. Sequence of clusters' depositions proceeds to form the thin film at short time as gas fluids through surface of substrate. In order to grow condensed thin film using series of cluster deposition, the effect of initial velocity, substrate temperature and density of clusters on property of deposited thin film, especially appearance of nanoscale pores inside thin film must be investigated. In this simulation, three different cluster sizes of 203, 653, 1563 atoms with different velocities (0, 10, 100, 1000 and 3000 m/s) were deposited on a Cu(0 0 1) substrate whose temperatures were set between 300 and 1000 K. Four clusters and one cluster were used in primary deposition and secondary deposition, respectively. We have clarified that adhesion between clusters and substrate is greatly influenced by initial velocity. As a result, the exfoliation pattern of deposited thin film is dependent on initial velocity and different between them. One borderline dividing whole region into porous region and nonporous region are obtained to show the effect of growth conditions on appearance of nanoscale pores inside thin film. Moreover, we have also shown that the likelihood of porous thin film is dependent on the point of impact of a cluster relative to previously deposited clusters.

  4. Investigation of growth, coverage and effectiveness of plasma assisted nano-films of fluorocarbon

    International Nuclear Information System (INIS)

    Joshi, Pratik P.; Pulikollu, Rajasekhar; Higgins, Steven R.; Hu Xiaoming; Mukhopadhyay, S.M.

    2006-01-01

    Plasma-assisted functional films have significant potential in various engineering applications. They can be tailored to impart desired properties by bonding specific molecular groups to the substrate surface. The aim of this investigation was to develop a fundamental understanding of the atomic level growth, coverage and functional effectiveness of plasma nano-films on flat surfaces and to explore their application-potential for complex and uneven shaped nano-materials. In this paper, results on plasma-assisted nano-scale fluorocarbon films, which are known for imparting inertness or hydrophobicity to the surface, will be discussed. The film deposition was studied as a function of time on flat single crystal surfaces of silicon, sapphire and graphite, using microwave plasma. X-ray photoelectron spectroscopy (XPS) was used for detailed study of composition and chemistry of the substrate and coating atoms, at all stages of deposition. Atomic force microscopy (AFM) was performed in parallel to study the coverage and growth morphology of these films at each stage. Combined XPS and AFM results indicated complete coverage of all the substrates at the nanometer scale. It was also shown that these films grew in a layer-by-layer fashion. The nano-films were also applied to complex and uneven shaped nano-structured and porous materials, such as microcellular porous foam and nano fibers. It was seen that these nano-films can be a viable approach for effective surface modification of complex or uneven shaped nano-materials

  5. Two-dimensional mapping of underdosed areas using radiochromic film for patients undergoing total skin electron beam radiotherapy

    International Nuclear Information System (INIS)

    Gamble, Lisa M.; Farrell, Thomas J.; Jones, Glenn W.; Hayward, Joseph E.

    2005-01-01

    Purpose: To demonstrate the viability of radiochromic film as an in vivo, two-dimensional dosimeter for the measurement of underdosed areas in patients undergoing total skin electron beam (TSEB) radiotherapy. The results were compared with thermoluminescent dosimeter measurements. Methods and Materials: Dosimetry results are reported for an inframammary fold of 2 patients treated using a modified version of the Stanford six-position (i.e., six-field and dual-beam) TSEB technique. The results are presented as contour plots of film optical density and percentage of dose. A linear dose profile measured from film was compared with the thermoluminescent dosimeter measurements. Results: The results showed that the percentage doses as measured by film are in good agreement with those measured by the thermoluminescent dosimeters. The isodose contour plots provided by film can be used as a two-dimensional dose map for a patient when determining the size of the supplemental patch fields. Conclusion: Radiochromic film is a viable dosimetry tool that the radiation oncologist can use to understand the surface dose heterogeneity better across complex concave regions of skin to help establish more appropriate margins to patch underdosed areas. Film could be used for patients undergoing TSEB for disorders such as mycosis fungoides or undergoing TSEB or regional skin electron beam for widespread skin metastases from breast cancer and other malignancies

  6. Stress relaxation and hillock growth in thin films

    International Nuclear Information System (INIS)

    Jackson, M.S.; Li, C.Y.

    1978-01-01

    The relaxation of thermal stress in a thin film adhering to a substrate of differing expansion coefficient is discussed. Good agreement is found between literature data on relaxation during isothermal anneals of Pb films at up to 350 0 K and model calculations based on a state variable description of plastic flow. The stress system during relaxation is explored, and the absence of diffusional creep is explained. The plasticity-dominated relaxation process suggested by this analysis is shown to be in good qualitative agreement with data on rapid relaxation over the course of a cycle between room and cryogenic temperatures. The implications of this for long-range material transport in the film are discussed. It is shown that hillock volume should increase over the course of a temperature cycle. Finally, a mechanism for hillock nucleation based on grain boundary sliding is suggested

  7. Self-regulated growth of LaVO3 thin films by hybrid molecular beam epitaxy

    International Nuclear Information System (INIS)

    Zhang, Hai-Tian; Engel-Herbert, Roman; Dedon, Liv R.; Martin, Lane W.

    2015-01-01

    LaVO 3 thin films were grown on SrTiO 3 (001) by hybrid molecular beam epitaxy. A volatile metalorganic precursor, vanadium oxytriisopropoxide (VTIP), and elemental La were co-supplied in the presence of a molecular oxygen flux. By keeping the La flux fixed and varying the VTIP flux, stoichiometric LaVO 3 films were obtained for a range of cation flux ratios, indicating the presence of a self-regulated growth window. Films grown under stoichiometric conditions were found to have the largest lattice parameter, which decreased monotonically with increasing amounts of excess La or V. Energy dispersive X-ray spectroscopy and Rutherford backscattering measurements were carried out to confirm film compositions. Stoichiometric growth of complex vanadate thin films independent of cation flux ratios expands upon the previously reported self-regulated growth of perovskite titanates using hybrid molecular beam epitaxy, thus demonstrating the general applicability of this growth approach to other complex oxide materials, where a precise control over film stoichiometry is demanded by the application

  8. In situ characterization of thin film growth: Boron nitride on silicon

    International Nuclear Information System (INIS)

    Fukarek, W.

    2001-01-01

    Real-time ellipsometry (RTE) in combination with particle flux measurement is applied to ion beam assisted deposition of boron nitride (BN) films. RTE is used as a tool for process diagnostic to improve the deposition stability. A novel technique for the determination of absolute density depth profiles from dynamic growth rate data and film forming particle flux is employed. From real-time cantilever curvature measurement and simultaneously recorded film thickness data instantaneous stress depth profiles are derived with a depth resolution in the nm range. The synergistic effects on the information obtained from RTE, particle flux, and cantilever bending data are demonstrated. The density of turbostratic BN (tBN) is found to increase slightly with film thickness while the compressive stress decreases, indicating an increasing quality and/or size of crystallites in the course of film growth. Refractive index and density depth profiles in cubic BN (cBN) films correspond perfectly to structural information obtained from dark field transmission electron microscope graphs. The established tBN/cBN two-layer model is found to be a crude approximation that has to be replaced by a three-layer model including nucleation, grain growth, and coalescence of cBN. The instantaneous compressive stress in a homogeneous tBN film is found to decrease, while the density increases during growth. The instantaneous compressive stress depth profiles in cBN films are more complex and not easy to understand but reliable information on the structural evolution during growth can be extracted

  9. Controlling growth rate anisotropy for formation of continuous ZnO thin films from seeded substrates

    International Nuclear Information System (INIS)

    Zhang, R H; Slamovich, E B; Handwerker, C A

    2013-01-01

    Solution-processed zinc oxide (ZnO) thin films are promising candidates for low-temperature-processable active layers in transparent thin film electronics. In this study, control of growth rate anisotropy using ZnO nanoparticle seeds, capping ions, and pH adjustment leads to a low-temperature (90 ° C) hydrothermal process for transparent and high-density ZnO thin films. The common 1D ZnO nanorod array was grown into a 2D continuous polycrystalline film using a short-time pure solution method. Growth rate anisotropy of ZnO crystals and the film morphology were tuned by varying the chloride (Cl − ) ion concentration and the initial pH of solutions of zinc nitrate and hexamethylenetetramine (HMTA), and the competitive adsorption effects of Cl − ions and HMTA ligands on the anisotropic growth behavior of ZnO crystals were proposed. The lateral growth of nanorods constituting the film was promoted by lowering the solution pH to accelerate the hydrolysis of HMTA, thereby allowing the adsorption effects from Cl − to dominate. By optimizing the growth conditions, a dense ∼100 nm thickness film was fabricated in 15 min from a solution of [Cl − ]/[Zn 2+ ] = 1.5 and pH= 4.8 ± 0.1. This film shows >80% optical transmittance and a field-effect mobility of 2.730 cm 2 V −1 s −1 at zero back-gate bias. (paper)

  10. Thin film growth studies using time-resolved x-ray scattering

    Science.gov (United States)

    Kowarik, Stefan

    2017-02-01

    Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.

  11. Surface structure deduced differences of copper foil and film for graphene CVD growth

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Junjun [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China); Hu, Baoshan, E-mail: hubaoshan@cqu.edu.cn [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China); Wei, Zidong; Jin, Yan [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China); Luo, Zhengtang [Department of Chemical and Biomolecular Engineering, The Hongkong University of Science and Technology, Kowloon (Hong Kong); Xia, Meirong [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China); Pan, Qingjiang [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Heilongjiang University, Harbin 150080 (China); Liu, Yunling [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China)

    2014-05-01

    Highlights: • We demonstrate the significant differences between Cu foil and film in the surface morphology and crystal orientation distribution. • The different surface structure leads to the distinctive influences of the CH₄ and H₂ concentrations on the thickness and quality of as-grown graphene. • Nucleation densities and growth rate differences at the initial growth stages on the Cu foil and film were investigated and discussed. Abstract: Graphene was synthesized on Cu foil and film by atmospheric pressure chemical vapor deposition (CVD) with CH₄ as carbon source. Electron backscattered scattering diffraction (EBSD) characterization demonstrates that the Cu foil surface after the H₂-assisted pre-annealing was almost composed of Cu(1 0 0) crystal facet with larger grain size of ~100 μm; meanwhile, the Cu film surface involved a variety of crystal facets of Cu(1 1 1), Cu(1 0 0), and Cu(1 1 0), with the relatively small grain size of ~10 μm. The different surface structure led to the distinctive influences of the CH₄ and H₂ concentrations on the thickness and quality of as-grown graphene. Further data demonstrate that the Cu foil enabled more nucleation densities and faster growth rates at the initial growth stages than the Cu film. Our results are beneficial for understanding the relationship between the metal surface structure and graphene CVD growth.

  12. Hybrid Thin Film Organosilica Sol-Gel Coatings To Support Neuronal Growth and Limit Astrocyte Growth.

    Science.gov (United States)

    Capeletti, Larissa Brentano; Cardoso, Mateus Borba; Dos Santos, João Henrique Zimnoch; He, Wei

    2016-10-07

    Thin films of silica prepared by a sol-gel process are becoming a feasible coating option for surface modification of implantable neural sensors without imposing adverse effects on the devices' electrical properties. In order to advance the application of such silica-based coatings in the context of neural interfacing, the characteristics of silica sol-gel are further tailored to gain active control of interactions between cells and the coating materials. By incorporating various readily available organotrialkoxysilanes carrying distinct organic functional groups during the sol-gel process, a library of hybrid organosilica coatings is developed and investigated. In vitro neural cultures using PC12 cells and primary cortical neurons both reveal that, among these different types of hybrid organosilica, the introduction of aminopropyl groups drastically transforms the silica into robust neural permissive substrate, supporting neuron adhesion and neurite outgrowth. Moreover, when this organosilica is cultured with astrocytes, a key type of glial cells responsible for glial scar response toward neural implants, such cell growth promoting effect is not observed. These findings highlight the potential of organo-group-bearing silica sol-gel to function as advanced coating materials to selectively modulate cell response and promote neural integration with implantable sensing devices.

  13. A novel diagnostic approach for studying silicon thin film growth

    NARCIS (Netherlands)

    Hoefnagels, J.P.M.

    2005-01-01

    In the deposition of thin films, the material properties are formed through the interaction of gas phase species with the growing surface. The resulting surface kinetics and chemistry is determined by the reactivity of the different gas phase species as well as by the surface chemical nature and may

  14. Optical properties of organic semiconductor thin films. Static spectra and real-time growth studies

    Energy Technology Data Exchange (ETDEWEB)

    Heinemeyer, Ute

    2009-07-20

    The aim of this work was to establish the anisotropic dielectric function of organic thin films on silicon covered with native oxide and to study their optical properties during film growth. While the work focuses mainly on the optical properties of Diindenoperylene (DIP) films, also the optical response of Pentacene (PEN) films during growth is studied for comparison. Spectroscopic ellipsometry and differential reflectance spectroscopy are used to determine the dielectric function of the films ex-situ and in-situ, i.e. in air and in ultrahigh vacuum. Additionally, Raman- and fluorescence spectroscopy is utilized to characterize the DIP films serving also as a basis for spatially resolved optical measurements beyond the diffraction limit. Furthermore, X-ray reflectometry and atomic force microscopy are used to determine important structural and morphological film properties. The absorption spectrum of DIP in solution serves as a monomer reference. The observed vibronic progression of the HOMO-LUMO transition allows the determination of the Huang-Rhys parameter experimentally, which is a measure of the electronic vibrational coupling. The corresponding breathing modes are measured by Raman spectroscopy. The optical properties of DIP films on native oxide show significant differences compared to the monomer spectrum due to intermolecular interactions. First of all, the thin film spectra are highly anisotropic due to the structural order of the films. Furthermore the Frenkel exciton transfer is studied and the energy difference between Frenkel and charge transfer excitons is determined. Real-time measurements reveal optical differences between interfacial or surface molecules and bulk molecules that play an important role for device applications. They are not only performed for DIP films but also for PEN films. While for DIP films on glass the appearance of a new mode is visible, the spectra of PEN show a pronounced energy red-shift during growth. It is shown how the

  15. Biodegradable and bioactive CGP/PVA film for fungal growth inhibition.

    Science.gov (United States)

    Silva, Bárbara Dumas S; Ulhoa, Cirano J; Batista, Karla A; Di Medeiros, Maria Carolina; Da Silva Filho, Rômulo Roosevelt; Yamashita, Fabio; Fernandes, Kátia F

    2012-07-01

    In this study, chitinolytic enzymes produced by Trichoderma asperellum were immobilized on a biodegradable film manufactured with a blend of cashew gum polysaccharide (CGP) and polyvinyl alcohol (PVA), and tested as a fungal growth inhibitor. The film was produced by casting a blend of CGP and PVA solution on glass molds. The CGP/PVA film showed 68% water solubility, tensile strength of 23.7 MPa, 187.2% elongation and 52% of mass loss after 90 days in soil. The presence of T-CWD enzymes immobilized by adsorption or covalent attachment resulted in effective inhibition of fungal growth. Sclerotinia sclerotiorum was the most sensitive organism, followed by Aspergillus niger and Penicillium sp. SEM micrograph showed that the presence of immobilized T-CWD enzymes on CGP/PVA film produced morphological modifications on vegetative and germinative structures of the microorganisms, particularly hyphae disruption and changes of spores shape. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Growth of conductive HfO{sub 2-x} thin films by reactive molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Erwin; Kurian, Jose; Alff, Lambert [Institut fuer Materialwissenschaft, TU Darmstadt (Germany); Kleebe, Hans-Joachim [Institut fuer Angewandte Geowissenschaften, TU Darmstadt (Germany)

    2009-07-01

    Thin films of oxygen deficient hafnium oxide were grown on single crystal c-cut and r-cut sapphire substrates by reactive molecular beam epitaxy. The oxidation conditions during growth were varied within a wide range using RF-activated oxygen. Hafnium oxide thin films were characterized using X-ray diffraction, resistivity measurements ({rho}-T) and transmission electron microscopy (TEM). The results show a dramatic increase in conductivity of the deposited oxygen deficient hafnium oxide thin films with decreasing oxidation conditions during growth. The electrical properties of deficient hafnium oxide thin films varied from insulating over semiconducting to conducting. X-ray diffraction data as well as TEM data rule out the possibility of conductivity due to metallic hafnium.

  17. Photoluminescence properties of ZnTe homoepitaxial films deposited by synchrotron-radiation-excited growth

    International Nuclear Information System (INIS)

    Nishio, Mitsuhiro; Hayashida, Kazuki; Harada, Hiroki; Mitsuishi, Yoshiaki; Guo Qixin; Ogawa, Hiroshi

    2001-01-01

    ZnTe homoepitaxial films have been deposited at substrate temperatures between 27 deg. C and 100 deg. C by synchrotron-radiation-excited growth using diethylzinc and diethyltelluride. Effects of diethylzinc transport rate and substrate temperature upon the photoluminescence properties of the ZnTe films have been clarified. Strong deep level emissions centered at 1.85 and 2.1 eV related to defects such as vacancy-impurity complex become emerged with increasing diethylzinc transport rate or substrate temperature. A sharply excitonic emission at 2.375 eV associated with shallow acceptors is observed and neither a donor-acceptor pair recombination nor a deep level luminescence signal is detected in the spectrum of the film grown under the nearly stoichiometric condition, which indicates that ZnTe films of good quality can be grown even at room temperature by this growth technique

  18. Total pubertal growth in patients with juvenile idiopathic arthritis treated with growth hormone: analysis of a single center.

    Science.gov (United States)

    Bechtold, S; Beyerlein, A; Ripperger, P; Roeb, J; Dalla Pozza, R; Häfner, R; Haas, J P; Schmidt, H

    2012-10-01

    Growth failure is a permanent sequelae in juvenile idiopathic arthritis (JIA). The aim of the study was to compare pubertal growth in control and growth hormone (GH) treated JIA subjects. 64 children with JIA at a mean age of 10.38 ± 2.80 years were enrolled and followed until final height (measured in standard deviation (SD) scores). 39 children (20 m) received GH therapy and 24 (9 m) served as controls. GH dose was 0.33 mg/kg/week. Linear regression analysis was performed to identify factors influencing total pubertal growth. Mean total pubertal growth was 21.1 ± 1.3 cm (mean ± SD) in GH treated JIA patients and 13.8 ± 1.5 cm in controls. Final height was significantly higher with GH treatment (-1.67 ± 1.20 SD) compared to controls (-3.20 ± 1.84 SD). Linear regression model identified age at onset of puberty (ß=-4.2,CI: -5.9, -2.6 in controls and ß=-2.3,CI: -3.6, -1.1 in GH treated) as the main factor for total pubertal growth. Final height SDS was determined by the difference to target height at onset of puberty (ß=-0.59;CI: -0.80, -0.37 in controls and ß=-0.30,CI: -0.52, -0.08 in GH treated), age at onset of puberty (ß=0.47;CI:0.02,0.93 in controls and 0.23;CI: -0.00,0.46 in GH treated) and height gain during puberty (ß=0.13;CI:0.05,0.21 in controls and ß=0.11;CI:0.07,0.16 in GH treated). Total pubertal growth in JIA patients treated with GH was increased by a factor of 1.5 greater in comparison to controls leading to a significantly better final height. To maximize final height GH treatment should be initiated early to reduce the height deficit at onset of puberty. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Does debt predict growth? An empirical analysis of the relationship between total debt and economic output

    Directory of Open Access Journals (Sweden)

    Willem Vanlaer

    2015-12-01

    Full Text Available Although the recent global financial crisis has stimulated a vast amount of research on the impact of public debt on economic growth and also increasingly on the role of private credit, the total levels of indebtedness of an economy have largely been ignored. This paper studies the impact of the total level of and increases in debt-to-GDP on economic growth for 26 developed countries in the short, medium and longer term. We analyse whether we can predict the future level of growth, simply by looking at the total level of debt, or increases in that debt level. We find that there is a negative correlation between high levels of debt and short term economic growth, but that this effect tapers in the medium and long term. Similarly, we find that rapid debt accumulation is negatively related to economic growth over the short term, the impact is less pronounced over the medium term and is non-existent over the long term.

  20. Buffer Film Assisted Growth of Dense MWCNTs on Copper Foils for Flexible Electrochemical Applications

    Directory of Open Access Journals (Sweden)

    Udomdej Pakdee

    2017-01-01

    Full Text Available The novel Inconel buffer films were prepared on copper foils using unbalance direct current (DC magnetron sputtering. These films were employed as buffer layers for supporting the dense growth of multiwalled carbon nanotubes (MWCNTs. Thermal chemical vapor deposition (CVD with metal alloys such as stainless steel (SS type 304 films was considered to synthesize MWCNTs. To understand the effectiveness of these buffer films, the MWCNTs grown on buffer-free layer were carried out as a comparison. The main problem such as the diffusion of catalysts into the oxide layer of metal substrate during the CVD process was solved together with a creation of good electrical contact between substrate and nanotubes. The morphologies, crystallinities, and electrochemical behaviors of MWCNTs grown on Inconel buffer films with 304 SS catalysts revealed the better results for applying in flexible electrochemical applications.

  1. Epitaxial Growth of Hard Ferrimagnetic Mn3Ge Film on Rhodium Buffer Layer

    Directory of Open Access Journals (Sweden)

    Atsushi Sugihara

    2015-06-01

    Full Text Available Mn\\(_3\\Ge has a tetragonal Heusler-like D0\\(_{22}\\ crystal structure, exhibiting a large uniaxial magnetic anisotropy and small saturation magnetization due to its ferrimagnetic spin structure; thus, it is a hard ferrimagnet. In this report, epitaxial growth of a Mn\\(_3\\Ge film on a Rh buffer layer was investigated for comparison with that of a film on a Cr buffer layer in terms of the lattice mismatch between Mn\\(_3\\Ge and the buffer layer. The film grown on Rh had much better crystalline quality than that grown on Cr, which can be attributed to the small lattice mismatch. Epitaxial films of Mn\\(_3\\Ge on Rh show somewhat small coercivity (\\(H_{\\rm c}\\ = 12.6 kOe and a large perpendicular magnetic anisotropy (\\(K_{\\rm u}\\ = 11.6 Merg/cm\\(^3\\, comparable to that of the film grown on Cr.

  2. Tailoring the nanoscale morphology of HKUST-1 thin films via codeposition and seeded growth.

    Science.gov (United States)

    Brower, Landon J; Gentry, Lauren K; Napier, Amanda L; Anderson, Mary E

    2017-01-01

    Integration of surface-anchored metal-organic frameworks (surMOFs) within hierarchical architectures is necessary for potential sensing, electronic, optical, or separation applications. It is important to understand the fundamentals of film formation for these surMOFs in order to develop strategies for their incorporation with nanoscale control over lateral and vertical dimensions. This research identified processing parameters to control the film morphology for surMOFs of HKUST-1 fabricated by codeposition and seeded deposition. Time and temperature were investigated to observe film formation, to control film thickness, and to tune morphology. Film thickness was investigated by ellipsometry, while film structure and film roughness were characterized by atomic force microscopy. Films formed via codeposition resulted in nanocrystallites anchored to the gold substrate. A dynamic process at the interface was observed with a low density of large particulates (above 100 nm) initially forming on the substrate; and over time these particulates were slowly replaced by the prevalence of smaller crystallites (ca. 10 nm) covering the substrate at a high density. Elevated temperature was found to expedite the growth process to obtain the full range of surface morphologies with reasonable processing times. Seed crystals formed by the codeposition method were stable and nucleated growth throughout a subsequent layer-by-layer deposition process. These seed crystals templated the final film structure and tailor the features in lateral and vertical directions. Using codeposition and seeded growth, different surface morphologies with controllable nanoscale dimensions can be designed and fabricated for integration of MOF systems directly into device architectures and sensor platforms.

  3. Tailoring the nanoscale morphology of HKUST-1 thin films via codeposition and seeded growth

    Directory of Open Access Journals (Sweden)

    Landon J. Brower

    2017-11-01

    Full Text Available Integration of surface-anchored metal-organic frameworks (surMOFs within hierarchical architectures is necessary for potential sensing, electronic, optical, or separation applications. It is important to understand the fundamentals of film formation for these surMOFs in order to develop strategies for their incorporation with nanoscale control over lateral and vertical dimensions. This research identified processing parameters to control the film morphology for surMOFs of HKUST-1 fabricated by codeposition and seeded deposition. Time and temperature were investigated to observe film formation, to control film thickness, and to tune morphology. Film thickness was investigated by ellipsometry, while film structure and film roughness were characterized by atomic force microscopy. Films formed via codeposition resulted in nanocrystallites anchored to the gold substrate. A dynamic process at the interface was observed with a low density of large particulates (above 100 nm initially forming on the substrate; and over time these particulates were slowly replaced by the prevalence of smaller crystallites (ca. 10 nm covering the substrate at a high density. Elevated temperature was found to expedite the growth process to obtain the full range of surface morphologies with reasonable processing times. Seed crystals formed by the codeposition method were stable and nucleated growth throughout a subsequent layer-by-layer deposition process. These seed crystals templated the final film structure and tailor the features in lateral and vertical directions. Using codeposition and seeded growth, different surface morphologies with controllable nanoscale dimensions can be designed and fabricated for integration of MOF systems directly into device architectures and sensor platforms.

  4. The Influence of Thermic Plastic Films on Vegetative and Reproductive Growth of Iceberg Lettuce 'Dublin'

    OpenAIRE

    Wael M. Semida; P. Hadley; W. Sobeih; N. A. El-Sawah; M. A. S. Barakat

    2013-01-01

    Photoselective plastic films with thermic properties are now available so that greenhouses clad with such plastics exhibit a higher degree of “Greenhouse Effect” with a consequent increase in night time temperature. In this study, we investigate the potential benefits of a range of thermic plastic films used as greenhouse cover materials on the vegetative and reproductive growth and development of Iceberg lettuce (Lactuca sativa L). Transplants were grown under thermic fi...

  5. Oxidation phase growth diagram of vanadium oxides film fabricated by rapid thermal annealing

    Institute of Scientific and Technical Information of China (English)

    Tamura KOZO; Zheng-cao LI; Yu-quan WANG; Jie NI; Yin HU; Zheng-jun ZHANG

    2009-01-01

    Thermal evaporation deposited vanadium oxide films were annealed in air by rapid thermal annealing (RTP). By adjusting the annealing temperature and time, a series of vanadium oxide films with various oxidation phases and surface morphologies were fabricated, and an oxidation phase growth diagram was established. It was observed that different oxidation phases appear at a limited and continuous annealing condition range, and the morphologic changes are related to the oxidation process.

  6. Growth of fine holes in polyethylenenaphthalate film irradiated by fission fragments

    International Nuclear Information System (INIS)

    Komaki, Y.; Tsujimura, S.

    1976-01-01

    Growth of fine holes by chemical etching in polyethylenenaphthalate films exposed to fission fragments were examined by measuring gas flow through the films. The etching rate along tracks, the radial etching rate, and the bulk etching rate were determined at effective hole diameters of 100 to 1000 A and hole densities of approximately 10 8 cm -2 . The effects of ethanol and surfactants on the etching rates were studied from the viewpoint of attaining less-tapered holes

  7. Effect of road side dust pollution on the growth and total chlorophyll ...

    African Journals Online (AJOL)

    The effect of dust in Vitis vinifera L. on its pigmentation and growth was studied in 2012. Measurements were taken for plants in the Campus University of Balochistan, Quetta. A significant reduction in plant length, cover, number of leaves and total chlorophyll contents for V. vinifera L. was observed. The maximum reduction ...

  8. Gas-temperature control in VHF- PECVD process for high-rate (>5 nm/s) growth of microcrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sobajima, Yasushi; Higuchi, Takuya; Chantana, Jakapan; Toyama, Toshihiko; Sada, Chitose; Matsuda, Akihisa; Okamoto, Hiroaki [Graduate School of Engineering Science, Osaka University, Toyonaka City (Japan)

    2010-04-15

    Surface-heating phenomenon by the radiation from high density plasma during growth of microcrystalline silicon ({mu}c-Si:H) thin films at high rate (> 5 nm/sec) is one of the crucial issues to be solved for obtaining high quality intrinsic-layer material for solar cells. We have utilized an optical emission spectroscopy (OES) in the plasma to observe the time evolution of gas temperature during film growth as well as the film-growth rate under {mu}c-Si:H deposition conditions at high rate. Gas temperature has been successfully controlled by changing total flow rate of monosilane (SiH{sub 4})/hydrogen (H{sub 2}) gas mixture, leading to a drastic improvement of optoelectronic properties in the resulting {mu}c-Si:H. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Growth and characterization of magnetite-maghemite thin films by the dip coating method

    Energy Technology Data Exchange (ETDEWEB)

    Velásquez, A. A., E-mail: avelas26@eafit.edu.edu.co; Arnedo, A. [Universidad EAFIT, Grupo de Electromagnetismo Aplicado (Colombia)

    2017-11-15

    We present the process of growth and characterization of magnetite-maghemite thin films obtained by the dip coating method. The thin films were deposited on glass substrates, using a ferrofluid of nanostructured magnetite-maghemite particles as precursor solution. During the growth of the films the following parameters were controlled: number of dips of the substrates, dip velocity of the substrates and drying times. The films were characterized by Atomic Force Microscopy, Scanning Elelectron Microscopy, four-point method for resistance measurement, Room Temperature Mössbauer Spectroscopy and Hall effect. Mössbauer measurements showed the presence of a sextet attributed to maghemite (γ-Fe{sub 2}O{sub 3}) and two doublets attributed to superparamagnetic magnetite (Fe{sub 3}O{sub 4}), indicating a distribution of oxidation states of the iron as well as a particle size distribution of the magnetic phases in the films. Atomic force microscopy measurements showed that the films cover quasi uniformly the substrates, existing in them some pores with sub-micron size. Scanning Electron Microscopy measurements showed a uniform structure in the films, with spherical particles with size around 10 nm. Voltage versus current measurements showed an ohmic response of the films for currents between 0 and 100 nA. On the other hand, Hall effect measurements showed a nonlinear response of the Hall voltage with the magnetic flux density applied perpendicular to the plane of the films, however the response is fairly linear for magnetic flux densities between 0.15 and 0.35 T approximately. The results suggest that the films are promising for application as magnetic flux density sensors.

  10. Growth and characterization of magnetite-maghemite thin films by the dip coating method

    International Nuclear Information System (INIS)

    Velásquez, A. A.; Arnedo, A.

    2017-01-01

    We present the process of growth and characterization of magnetite-maghemite thin films obtained by the dip coating method. The thin films were deposited on glass substrates, using a ferrofluid of nanostructured magnetite-maghemite particles as precursor solution. During the growth of the films the following parameters were controlled: number of dips of the substrates, dip velocity of the substrates and drying times. The films were characterized by Atomic Force Microscopy, Scanning Elelectron Microscopy, four-point method for resistance measurement, Room Temperature Mössbauer Spectroscopy and Hall effect. Mössbauer measurements showed the presence of a sextet attributed to maghemite (γ-Fe_2O_3) and two doublets attributed to superparamagnetic magnetite (Fe_3O_4), indicating a distribution of oxidation states of the iron as well as a particle size distribution of the magnetic phases in the films. Atomic force microscopy measurements showed that the films cover quasi uniformly the substrates, existing in them some pores with sub-micron size. Scanning Electron Microscopy measurements showed a uniform structure in the films, with spherical particles with size around 10 nm. Voltage versus current measurements showed an ohmic response of the films for currents between 0 and 100 nA. On the other hand, Hall effect measurements showed a nonlinear response of the Hall voltage with the magnetic flux density applied perpendicular to the plane of the films, however the response is fairly linear for magnetic flux densities between 0.15 and 0.35 T approximately. The results suggest that the films are promising for application as magnetic flux density sensors.

  11. Role of high microwave power on growth and microstructure of thick nanocrystalline diamond films: A comparison with large grain polycrystalline diamond films

    Science.gov (United States)

    Tang, C. J.; Fernandes, A. J. S.; Girão, A. V.; Pereira, S.; Shi, Fa-Nian; Soares, M. R.; Costa, F.; Neves, A. J.; Pinto, J. L.

    2014-03-01

    In this work, we study the growth habit of nanocrystalline diamond (NCD) films by exploring the very high power regime, up to 4 kW, in a 5 kW microwave plasma chemical vapour deposition (MPCVD) reactor, through addition of a small amount of nitrogen and oxygen (0.24%) into 4% CH4 in H2 plasma. The coupled effect of high microwave power and substrate temperature on NCD growth behaviour is systematically investigated by varying only power, while fixing the remaining operating parameters. When the power increases from 2 kW to 4 kW, resulting also in rise of the Si substrate temperature higher than 150 °C, the diamond films obtained maintain the NCD habit, while the growth rate increases significantly. The highest growth rate of 4.6 μm/h is achieved for the film grown at 4 kW, which represents a growth rate enhancement of about 15 times compared with that obtained when using 2 kW power. Possible factors responsible for such remarkable growth rate enhancement of the NCD films are discussed. The evolution of NCD growth characteristics such as morphology, microstructure and texture is studied by growing thick films and comparing it with that of large grain polycrystalline (PCD) films. One important characteristic of the NCD films obtained, in contrast to PCD films, is that irrespective of deposition time (i.e. film thickness), their grain size and surface roughness remain in the nanometer range throughout the growth. Finally, based on our present and previous experimental results, a potential parameter window is established for fast growth of NCD films under high power conditions.

  12. Epitaxial growth of textured YBa2Cu3O7-δ films on silver

    International Nuclear Information System (INIS)

    Liu Dan-Min; Liu Wei-Peng; Suo Hong-Li; Zhou Mei-Ling

    2005-01-01

    YBa 2 Cu 3 O 7-δ (YBCO) films were deposited on (100), (110) and (111) oriented silver single crystals and {100} left angle 100 right angle, {110} left angle 211 right angle, {110} left angle 100 right angle +{110} left angle 011 right angle {110} left angle 011 right angle and {012} left angle 100 right angle textured Ag substrates using pulsed laser deposition. The relationship between the epitaxial growth YBCO film and silver substrate has been determined. It is shown that among polycrystalline Ag substrates, {110} left angle 011 right angle textured tape is suitable for the deposition of YBCO thin films having strong texture. (orig.)

  13. Growth of high Tc Bi-Sr-Ca-Cu-O thick films

    International Nuclear Information System (INIS)

    Chaudhry, Sangeeta; Khare, Neeraj; Gupta, A.K.; Nagpal, K.C.; Ojha, V.N.; Reddy, G.S.N.; Tomar, V.S.

    1991-01-01

    Thick films of Bi-Sr-Ca-Cu-O were deposited on (100) MgO substrates by screen-printing technique with the starting composition 1112. To attain the superconducting state, the films were subjected to two-step heat-treatment. R-T and XRD have been studied for films annealed at different durations of the second step. Initially T c (R=O) increased from 77 to 103 K as the annealing duration was increased after which T c decreased. Kinetics of the growth of high T c phase is discussed in the light of results. (author). 7 refs., 2 figs., 1 tab

  14. Epitaxial thin film growth and properties of unconventional oxide superconductors. Cuprates and cobaltates

    International Nuclear Information System (INIS)

    Krockenberger, Y.

    2006-01-01

    The discovery of high-temperature superconductors has strongly driven the development of suited thin film fabrication methods of complex oxides. One way is the adaptation of molecular beam epitaxy (MBE) for the growth of oxide materials. Another approach is the use of pulsed laser deposition (PLD) which has the advantage of good stoichiometry transfer from target to the substrate. Both techniques are used within this thesis. Epitaxial thin films of new materials are of course needed for future applications. In addition, the controlled synthesis of thin film matter which can be formed far away from thermal equilibrium allows for the investigation of fundamental physical materials properties. (orig.)

  15. Epitaxial thin film growth and properties of unconventional oxide superconductors. Cuprates and cobaltates

    Energy Technology Data Exchange (ETDEWEB)

    Krockenberger, Y.

    2006-07-01

    The discovery of high-temperature superconductors has strongly driven the development of suited thin film fabrication methods of complex oxides. One way is the adaptation of molecular beam epitaxy (MBE) for the growth of oxide materials. Another approach is the use of pulsed laser deposition (PLD) which has the advantage of good stoichiometry transfer from target to the substrate. Both techniques are used within this thesis. Epitaxial thin films of new materials are of course needed for future applications. In addition, the controlled synthesis of thin film matter which can be formed far away from thermal equilibrium allows for the investigation of fundamental physical materials properties. (orig.)

  16. Study both films structure and fractal growth in the T-10 tokamak

    International Nuclear Information System (INIS)

    Khimchenko, L.N.; Budaev, V.P.; Guseva, M.I.; Kamneva, S.A.; Kolbasov, B.N.; Kuteev, B.V.; Martynenko, Yu.V.; Svechnikov, N.Yu.; Stankevich, V.G.; Loginov, B.A.; Romanov, P.B.

    2005-01-01

    In the paper results of films growth mechanism study, their internal structure are summarized. The mechanism leading to hydrogen capture effect on the first wall at over dusting stage is stated. Films internal structure have been studied with help of synchrotron radiation, electron paramagnetic resonance, IR reflection spectra, thermal gravimetric methods, spectroscopy in the vision spectrum range and UV vacuum range. Structure of the films surfaces have been examined with help of electron microscopy, probe scanning tunnel and atom-force microscopy, as well as miniature scanning tunnel microscope placed in the T-10 tokamak

  17. Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth

    International Nuclear Information System (INIS)

    Thiele, U

    2010-01-01

    In the present contribution we review basic mathematical results for three physical systems involving self-organizing solid or liquid films at solid surfaces. The films may undergo a structuring process by dewetting, evaporation/condensation or epitaxial growth, respectively. We highlight similarities and differences of the three systems based on the observation that in certain limits all of them may be described using models of similar form, i.e. time evolution equations for the film thickness profile. Those equations represent gradient dynamics characterized by mobility functions and an underlying energy functional. Two basic steps of mathematical analysis are used to compare the different systems. First, we discuss the linear stability of homogeneous steady states, i.e. flat films, and second the systematics of non-trivial steady states, i.e. drop/hole states for dewetting films and quantum-dot states in epitaxial growth, respectively. Our aim is to illustrate that the underlying solution structure might be very complex as in the case of epitaxial growth but can be better understood when comparing the much simpler results for the dewetting liquid film. We furthermore show that the numerical continuation techniques employed can shed some light on this structure in a more convenient way than time-stepping methods. Finally we discuss that the usage of the employed general formulation does not only relate seemingly unrelated physical systems mathematically, but does allow as well for discussing model extensions in a more unified way.

  18. Multi-Directional Growth of Aligned Carbon Nanotubes Over Catalyst Film Prepared by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Zhou Kai

    2010-01-01

    Full Text Available Abstract The structure of vertically aligned carbon nanotubes (CNTs severely depends on the properties of pre-prepared catalyst films. Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD was employed to deposit uniform Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology. The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future.

  19. An XPS study of pulsed plasma polymerised allyl alcohol film growth on polyurethane

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, Lucy [Department of Chemistry, University of York, Heslington, York YO10 5DD (United Kingdom); Bismarck, Alexander [Department of Chemical Engineering, Polymer and Composite Engineering (PaCE) Group, Imperial College London, London SW7 2AZ (United Kingdom); Lee, Adam F. [Department of Chemistry, University of York, Heslington, York YO10 5DD (United Kingdom); Wilson, Darren [Smith and Nephew Research Centre, York Science Park, Heslington, York YO10 5DF (United Kingdom); Wilson, Karen [Department of Chemistry, University of York, Heslington, York YO10 5DD (United Kingdom)]. E-mail: kw13@york.ac.uk

    2006-09-30

    The growth of highly functionalised poly allyl alcohol films by pulsed plasma polymerisation of CH{sub 2} =CHCH{sub 2}OH on biomedical grade polyurethane has been followed by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. Film thickness is observed to increase approximately linearly with plasma modification time, suggesting a layer-by-layer growth mode of poly allyl alcohol. Water contact angle measurements reveal the change in the surface free energy of wetting decreases linearly with plasma modification up to the monolayer point after which a constant limiting value of -24 mJ m{sup -2} was attained. Films prepared at 20 W plasma power with a duty cycle of 10 {mu}s:500 {mu}s exhibit a high degree of hydroxyl (-OH) retention with minimal fragmentation of the monomer observed. Increasing the plasma power up to 125 W is found to improve -OH retention at the expense of ether formation generating films close to the monomer stoichiometry. Duty cycle plays an important role in controlling both film composition and thickness, with longer off times increasing -OH retention, while longer on times enhance allyl alcohol film growth.

  20. Epitaxial growth and properties of YBaCuO thin films

    International Nuclear Information System (INIS)

    Geerk, J.; Linker, G.; Meyer, O.

    1989-08-01

    The growth quality of YBaCuO thin films deposited by sputtering on different substrates (Al 2 O 3 , MgO, SrTiO 3 , Zr(Y)O 2 ) has been studied by X-ray diffraction and channeling experiments as a function of the deposition temperature. Besides the substrate orientation, the substrate temperature is the parameter determining whether films grow in c-, a-, (110) or mixed directions. Epitaxial growth correlates with high critical current values in the films of up to 5.5x10 6 A/cm 2 at 77 K. Ultrathin films with thicknesses down to 2 nm were grown revealing three-dimensional superconducting behaviour. Films on (100) SrTiO 3 of 9 nm thickness and below are partially strained indicating commensurate growth. From the analysis of the surface disorder 1 displaced Ba atom per Ba 2 Y row was obtained indicating that the disordered layer thickness is about 0.6 nm. Tunnel junctions fabricated on these films reveal gap-like structures near ±16 mV and ±30 mV. (orig.) [de

  1. A stochastic model of solid state thin film deposition: Application to chalcopyrite growth

    Directory of Open Access Journals (Sweden)

    Robert J. Lovelett

    2016-04-01

    Full Text Available Developing high fidelity quantitative models of solid state reaction systems can be challenging, especially in deposition systems where, in addition to the multiple competing processes occurring simultaneously, the solid interacts with its atmosphere. In this work, we develop a model for the growth of a thin solid film where species from the atmosphere adsorb, diffuse, and react with the film. The model is mesoscale and describes an entire film with thickness on the order of microns. Because it is stochastic, the model allows us to examine inhomogeneities and agglomerations that would be impossible to characterize with deterministic methods. We demonstrate the modeling approach with the example of chalcopyrite Cu(InGa(SeS2 thin film growth via precursor reaction, which is a common industrial method for fabricating thin film photovoltaic modules. The model is used to understand how and why through-film variation in the composition of Cu(InGa(SeS2 thin films arises and persists. We believe that the model will be valuable as an effective quantitative description of many other materials systems used in semiconductors, energy storage, and other fast-growing industries.

  2. Setup for in situ X-ray diffraction studies of thin film growth by magnetron sputtering

    CERN Document Server

    Ellmer, K; Weiss, V; Rossner, H

    2001-01-01

    A novel method is described for the in situ-investigation of nucleation and growth of thin films during magnetron sputtering. Energy dispersive X-ray diffraction with synchrotron light is used for the structural analysis during film growth. An in situ-magnetron sputtering chamber was constructed and installed at a synchrotron radiation beam line with a bending magnet. The white synchrotron light (1-70 keV) passes the sputtering chamber through Kapton windows and hits one of the substrates on a four-fold sample holder. The diffracted beam, observed under a fixed diffraction angle between 3 deg. and 10 deg., is energy analyzed by a high purity Ge-detector. The in situ-EDXRD setup is demonstrated for the growth of tin-doped indium oxide (ITO) films prepared by reactive magnetron sputtering from a metallic target.

  3. The properties of TiN ultra-thin films grown on SiO{sub 2} substrate by reactive high power impulse magnetron sputtering under various growth angles

    Energy Technology Data Exchange (ETDEWEB)

    Shayestehaminzadeh, S., E-mail: ses30@hi.is [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Tryggvason, T.K. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Karlsson, L. [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany); Olafsson, S. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Gudmundsson, J.T. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); University of Michigan-Shanghai Jiao Tong University, University Joint Institute, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China)

    2013-12-02

    Thin TiN films were grown on SiO{sub 2} by reactive high power impulse magnetron sputtering (HiPIMS) and conventional dc magnetron sputtering (dcMS) while varying the angle between the target and the substrate surface from 0° (on-axis growth) to 90° (off-axis growth). Surface morphology and structural characterization were carried out using X-ray diffraction and reflection methods and the film properties were compared. The dcMS process shows higher growth rate than the HiPIMS process for on-axis grown films but the dcMS growth rate drops drastically for off-axis growth while the HiPIMS growth rate decreases slowly with increased angle between target and substrate for off-axis growth and becomes comparable to the dcMS growth rate. The dcMS grown films exhibit angle dependence in the density and surface roughness while the HiPIMS process creates denser and smoother films that are less angle dependent in all aspects. It was observed that the HiPIMS grown films remain poly-crystalline for all angles of rotation while the dcMS grown films are somewhat amorphous after 60°. The [111] and [200] grain sizes are comparable to the total film thickness in the HiPIMS grown films for all angles of rotation. In the case of dcMS, the [111], [200] and [220] grain sizes are roughly of the same size and much smaller than the total thickness for all growth angles except at 60° and higher. - Highlights: • TiN films were grown on SiO{sub 2} by HiPIMS and dcMS under various growth angles. • Influence of growth angle α = 0–90° on deposition rate and film quality was studied. • The HiPIMS process produces denser and smoother films for all growth angles. • At α = 0°, the growth rate of HiPIMS is 25% of dcMS while it is 50% at 90°. • The HiPIMS grown films remain poly-crystalline for all growth angles.

  4. Industry efficiency and total factor productivity growth under resources and environmental constraint in China.

    Science.gov (United States)

    Tao, Feng; Li, Ling; Xia, X H

    2012-01-01

    The growth of China's industry has been seriously depending on energy and environment. This paper attempts to apply the directional distance function and the Luenberger productivity index to measure the environmental efficiency, environmental total factor productivity, and its components at the level of subindustry in China over the period from 1999 to 2009 while considering energy consumption and emission of pollutants. This paper also empirically examines the determinants of efficiency and productivity change. The major findings are as follows. Firstly, the main sources of environmental inefficiency of China's industry are the inefficiency of gross industrial output value, the excessive energy consumption, and pollutant emissions. Secondly, the highest growth rate of environmental total factor productivity among the three industrial categories is manufacturing, followed by mining, and production and supply of electricity, gas, and water. Thirdly, foreign direct investment, capital-labor ratio, ownership structure, energy consumption structure, and environmental regulation have varying degrees of effects on the environmental efficiency and environmental total factor productivity.

  5. Growth of vertically aligned ZnO nanorods using textured ZnO films

    Directory of Open Access Journals (Sweden)

    Meléndrez Manuel

    2011-01-01

    Full Text Available Abstract A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100 substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.

  6. Growth and surface characterization of sputter-deposited molybdenum oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ramana, C.V. [Nanoscience and Surface Chemistry Laboratory, Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)]. E-mail: ramanacv@umich.edu; Atuchin, V.V. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Kesler, V.G. [Technical Centre, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Kochubey, V.A. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Pokrovsky, L.D. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Shutthanandan, V. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Becker, U. [Nanoscience and Surface Chemistry Laboratory, Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Ewing, R.C. [Nanoscience and Surface Chemistry Laboratory, Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2007-04-15

    Molybdenum oxide thin films were produced by magnetron sputtering using a molybdenum (Mo) target. The sputtering was performed in a reactive atmosphere of an argon-oxygen gas mixture under varying conditions of substrate temperature (T {sub s}) and oxygen partial pressure (pO{sub 2}). The effect of T {sub s} and pO{sub 2} on the growth and microstructure of molybdenum oxide films was examined in detail using reflection high-energy electron diffraction (RHEED), Rutherford backscattering spectrometry (RBS), energy-dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) measurements. The analyses indicate that the effect of T {sub s} and pO{sub 2} on the microstructure and phase of the grown molybdenum oxide thin films is remarkable. RHEED and RBS results indicate that the films grown at 445 deg. C under 62.3% O{sub 2} pressure were stoichiometric and polycrystalline MoO{sub 3}. Films grown at lower pO{sub 2} were non-stoichiometric MoO {sub x} films with the presence of secondary phase. The microstructure of the grown Mo oxide films is discussed and conditions were optimized to produce phase pure, stoichiometric, and highly textured polycrystalline MoO{sub 3} films.

  7. Growth and surface characterization of sputter-deposited molybdenum oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ramana, Chintalapalle V.; Atuchin, Victor V.; Kesler, V. G.; Kochubey, V. A.; Pokrovsky, L. D.; Shutthanandan, V.; Becker, U.; Ewing, Rodney C.

    2007-04-15

    Molybdenum oxide thin films were produced by magnetron sputtering using a molybdenum (Mo) target. The sputtering was performed in a reactive atmosphere of argon-oxygen gas mixture under varying conditions of substrate temperature (Ts) and oxygen partial pressure (pO2). The effect of Ts and pO2 on the growth and microstructure of molybdenum oxide films was examined in detail using reflection high-energy electron diffraction (RHEED), Rutherford backscattering spectrometry (RBS), energy dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) measurements. The analyses indicate that the effect of Ts and pO2 on the microstructure and phase of the grown molybdenum oxide thin films is remarkable. RHEED and RBS results indicate that the films grown at 445 *C under 62.3% O2 pressure were stoichiometric and polycrystalline MoO3. Films grown at lower pO2 were nonstoichiometric MoOx films with the presence of secondary phase. The microstructure of the grown Mo oxide films is discussed and conditions were optimized to produce phase pure, stoichiometric, and highly textured polycrystalline MoO3 films.

  8. Pulsed-laser deposition and growth studies of Bi3Fe5O12 thin films

    International Nuclear Information System (INIS)

    Lux, Robert; Heinrich, Andreas; Leitenmeier, Stephan; Koerner, Timo; Herbort, Michael; Stritzker, Bernd

    2006-01-01

    Magneto-optical garnets are attractive because of their high Faraday rotation and low optical loss in the near infrared. Therefore their use is generally in nonreciprocal devices, i.e., as optical isolators in optical communication. In this paper we present data concerning the deposition of Bi 3 Fe 5 O 12 (BIG) thin films on (100) and (111) Gd 3 Ga 5 O 12 substrates using pulsed-laser deposition. Laser-induced processes on the surface of the oxide target used for ablation were analyzed and numerous films were deposited. We found the BIG film quality to be strongly affected by oxygen pressure, laser energy density, and the Bi/Fe film ratio, whereas temperature had a minor influence. We also investigated the BIG-film deposition using a target pressed from metallic Bi and Fe powders and found information on the growth behavior of BIG. We report on details of the film deposition and film properties determined by environmental scanning electron microscopy, energy dispersive x-ray analysis, Rutherford backscattering spectroscopy, and x-ray diffraction. In addition, we determined the Faraday rotation of the films

  9. Growth and analysis of highly oriented (11n) BCSCO films for device research

    Energy Technology Data Exchange (ETDEWEB)

    Raina, K.K.; Pandey, R.K. [Texas A& M Univ., College Station, TX (United States)

    1994-12-31

    Films of BCSCO superconductor of the type Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub x} have been grown by liquid phase epitaxy method (LPE), using a partially closed growth chamber. The films were grown on (001) and (110) NdGaO{sub 3} substrates by slow cooling process in an optimized temperature range below the peritectic melting point (880{degrees}C) of Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub 8}. Optimization of parameters, such as seed rotation, soak of initial growth temperature and growth period results in the formation of 2122 phase BCSCO films. The films grown at rotation rates of less than 30 and more than 70 rpm are observed to be associated with the second phase of Sr-Ca-Cu-O system. Higher growth temperatures (>860{degrees}C) also encourage to the formation of this phase. XRD measurements show that the films grown on (110) NdGaO{sub 3} have a preferred (11n)-orientation. It is pertinent to mention here that in our earlier results published elsewhere we obtained c-axis oriented Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub 8} phase films on (001) NdGaO{sub 3} substrate. Critical current density is found to be higher for the films grown on (110) than (001) NdGaO{sub 3} substrate orientation. The best values of zero resistance (T{sub co}) and critical current density obtained are 87 K and 10{sup 5} A/cm{sup 2}, respectively.

  10. Mechanistic Insights into Growth of Surface-Mounted Metal-Organic Framework Films Resolved by Infrared (Nano-) Spectroscopy

    NARCIS (Netherlands)

    Delen, Guusje; Ristanovic, Zoran; Mandemaker, Laurens D. B.; Weckhuysen, Bert M.

    2018-01-01

    Control over assembly, orientation, and defect-free growth of metal-organic framework (MOF) films is crucial for their future applications. A layer-by-layer approach is considered a suitable method to synthesize highly oriented films of numerous MOF topologies, but the initial stages of the film

  11. In situ growth of p and n-type graphene thin films and diodes by pulsed laser deposition

    KAUST Repository

    Sarath Kumar, S. R.; Nayak, Pradipta K.; Hedhili, Mohamed N.; Khan, M. A.; Alshareef, Husam N.

    2013-01-01

    We report the in situ growth of p and n-type graphene thin films by ultraviolet pulsed laser deposition in the presence of argon and nitrogen, respectively. Electron microscopy and Raman studies confirmed the growth, while temperature dependent

  12. Decoding Nucleation and Growth of Zeolitic Imidazolate Framework Thin Films with Atomic Force Microscopy and Vibrational Spectroscopy.

    Science.gov (United States)

    Öztürk, Zafer; Filez, Matthias; Weckhuysen, Bert M

    2017-08-10

    The synthesis of metal-organic framework (MOF) thin films has garnered significant attention during the past decade. By better understanding the parameters governing the nucleation and growth of such thin films, their properties can be rationally tuned, empowering their application as (reactive) membranes. Here, a combined AFM-vibrational spectroscopy research strategy is employed to detail the chemistries governing the nucleation and growth of zeolitic imidazolate framework (ZIF) thin films, in particular isostructural Co-ZIF-67 and Zn-ZIF-8. First, a single step direct synthesis approach is used to investigate the influence of different synthesis parameters -metal/linker ratio, temperature, and metal type- on the thin film nucleation and growth behaviour. While the metal/linker ratio has a pronounced effect on the thin film nucleation rate, the temperature mainly influences the growth kinetics of nuclei forming the thin film. In addition, the nucleation and growth of ZIF thin films is shown to be highly dependent on the electronegativity of the metal type. Thin-film thickness control can be achieved by using a multistep synthesis strategy, implying repetitive applications of single step deposition under identical synthesis conditions, for which a growth mechanism is proposed. This study provides insight into the influence of synthesis parameters on the ZIF thin film properties, using tools at hand to rationally tune MOF thin film properties. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  13. Growth, morphology, and conductivity in semimetallic/metallic films on Si(001)

    Energy Technology Data Exchange (ETDEWEB)

    Jnawali, Giriraj

    2009-06-09

    This dissertation deals with the study of epitaxial growth of semimetallic (Bi) and metallic (Ag) films on Si(001) as well as in situ electrical transport study of those films via surface manipulation. The focus of the transport measurements is to study the influence of the surface morphology or structure on the resistance of the film. In spite of the large lattice mismatch and different lattice geometry, it is possible to grow epitaxial Bi(111) films on Si(001) substrates, which are surprisingly smooth, relaxed and almost free of defects. Due to the two-fold symmetry of the substrates, the Bi(111) film is composed of crystallites rotated by 90 with respect to each other. Annealing of 6 nm film from 150 K to 450 K enables the formation of a periodic interfacial misfit dislocations, which accommodates a remaining lattice mismatch of 2.3 %. The surface/interface roughness and the bulk defect density of the film found to be extremely low, indicating the high crystalline quality of the film with atomically smooth surface and abrupt interface. Similar to the Bi films, Ag grows in a (111) orientation on Si(001) with two 90 rotated domains. The remaining strain of 2.2 % (tensile) is accommodated by the formation of an ordered network of dislocations. The Ag film exhibits atomically smooth surface. Those Bi films and Ag films were used as model systems to study the influence of the surface morphology on the electrical resistance. Surprisingly, all the Bi films (3-170 nm thicknesses) have shown an anomalous behavior of conductance with temperature and thickness. As in the case of doped semiconductor, the conductance increases exponentially from 150 K to 300 K and saturates at 350 K before finally decreasing with temperature. In situ measurements of the resistance during additional Bi deposition on the smooth Bi(111) films exhibit a square root dependent with coverage after a linear increase at very low coverage (1 % of a BL). During additional deposition of Bi, carriers are

  14. Oxide thin films for spintronics application growth and characterization

    OpenAIRE

    Popovici, Nicoleta, 1973-

    2009-01-01

    Tese de doutoramento, Física (Física), Universidade de Lisboa, Faculdade de Ciências, 2009 During my PhD research I have synthesized thin films of a material known as a diluted magnetic semiconductor (DMS) using the pulsed laser deposition (PLD) technique. This material is envisioned to be of importance in the emerging field of spintronics where both the charge and the spin of the carriers can be combined to yield unique functionalities. It was envisaged that if spin polarized charge carri...

  15. Effects of a magnetic field on growth of porous alumina films on aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Ispas, Adriana; Bund, Andreas [Technische Universitaet Dresden, Physikalische Chemie und Elektrochemie, 01062 Dresden (Germany); Vrublevsky, Igor, E-mail: vrublevsky@bsuir.edu.b [Belarusian State University of Informatics and Radioelectronics Minsk, Department of Micro and Nanoelectronics, 220013 Minsk (Belarus)

    2010-05-01

    The effects induced by a magnetic field on the oxide film growth on aluminum in sulfuric, oxalic, phosphoric and sulfamic acid, and on current transients during re-anodizing of porous alumina films in the barrier-type electrolyte, were studied. Aluminum films of 100 nm thickness were prepared by thermal evaporation on Si wafer substrates. We could show that the duration of the anodizing process increased by 33% during anodizing in sulfuric acid when a magnetic field was applied (0.7 T), compared to the process without a magnetic field. Interestingly, such a magnetic field effect was not found during anodizing in oxalic and sulfamic acid. The pore intervals were decreased by ca. 17% in oxalic acid. These findings were attributed to variations in electronic properties of the anodic oxide films formed in various electrolytes and interpreted on the basis of the influence of trapped electrons on the mobility of ions migrating during the film growth. The spin dependent tunneling of electrons into the surface layer of the oxide under the magnetic field could be responsible for the shifts of the current transients to lower potentials during re-anodizing of heat-treated oxalic and phosphoric acid alumina films.

  16. Growth in Total Height and Its Components and Cardiometabolic Health in Childhood

    DEFF Research Database (Denmark)

    Haugaard, Line Klingen; Baker, Jennifer Lyn; Perng, Wei

    2016-01-01

    BACKGROUND: Short stature or short legs is associated with cardiometabolic disease. Few studies have addressed this issue in children, incorporated repeated measures, or studied modern cohorts. METHODS: We examined if change in total height, leg length and trunk length between two time points from...... was a cardiometabolic risk score based on sex-specific internal z-scores for systolic blood pressure, waist circumference, homeostatic model assessment of insulin resistance, triglycerides and high-density lipoprotein-cholesterol. RESULTS: Mean (SD) total height was 97.9 (4.5) cm in boys and 97.1 (4.7) cm in girls...... in early childhood and 129.1 (7.2) cm in boys and 128.3 (7.9) cm in girls in mid-childhood. Trunk length constituted about half of total height. In linear regression models adjusted for parental anthropometry and socio-demographics, faster growth in total height, leg length and particularly trunk length...

  17. Interface-Limited Spherulitic Growth of Hydroxyapatite/Chondroitin Sulfate Composite Enamel-like Films

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Xiyan; Wang, Mu

    2012-02-01

    Understanding and mimicking the growth of hard tissues such as tooth enamel may lead to innovative approaches toward engineering novel functional materials and providing new therapeutics. Up to now, in vitro growth of enamel-like materials is still a great challenge, and the microscopic formation mechanisms are far from well understood. Here we report synthesis of large-scale hydroxyapatite (HAP) and chondroitin sulfate (ChS) composite films by an efficient solution-air interface growth method. The products have the characteristic hierarchical prism structures of enamel and the mechanical properties comparable to dentin. We demonstrate that the films are assembled by spherulites nucleated at the solution surface. The growth of the spherulites is limited by the interfaces between them as well as between the solution and air, leading to the ordered prism structure. The results are beneficial for a clearer understanding of the fundamentals of tooth enamel formation.

  18. Epitaxial growth of Fe-based superconductor thin films

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Sven; Haenisch, Jens; Holzapfel, Bernhard [Institut fuer Technische Physik, Karlsruher Institut fuer Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2016-07-01

    The Fe-based superconductors (FBS), discovered in 2008, are not only interesting for possible applications due to their large upper critical fields and low anisotropies, but also for basic understanding of unconventional superconductivity. With their properties, they constitute a link between the classic low-T{sub c} superconductors (low anisotropies, low thermal fluctuations, s-wave type symmetry) and the oxocuprates (T{sub c} up to 55 K, large H{sub c2}, unconventional pairing). Their multi-band nature reminds of MgB{sub 2}. We prepare thin films of FBS in the so called 122 family, namely Co- and P-doped BaFe{sub 2}As{sub 2} to investigate application relevant properties, such as critical current density J{sub c}, by pulsed laser deposition using a frequency-tripled Nd:YAG laser (λ = 355 nm). Microstructure and chemical composition will be investigated by XRD, AFM and SEM, and electrical transport using a 14 T PPMS. The results are compared to literature data on films grown at different wavelengths.

  19. Domain growth of carbon nanotubes assisted by dewetting of thin catalyst precursor films

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Alok Kumar [Defence Materials and Stores R and D Establishment (DRDO), GT Road, Kanpur 208013 (India); Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016 (India); Sachan, Priyanka; Samanta, Chandan [Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016 (India); Mukhopadhyay, Kingsuk [Defence Materials and Stores R and D Establishment (DRDO), GT Road, Kanpur 208013 (India); Sharma, Ashutosh, E-mail: ashutos@iitk.ac.in [Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016 (India)

    2014-01-01

    We explore self-organized dewetting of ultrathin films of a novel metal complex as a one step surface patterning method to create nanoislands of iron, using which spatially separated carbon nanostructures were synthesized. Dewetting of ultrathin metal complex films was induced by two different methods: liquid solvent exposure and thermal annealing to engender surface patterning. For thermal dewetting, thin films of the iron oleate complex were dewetted at high temperature. In the case of liquid solvent assisted dewetting, the metal complex, mixed with a sacrificial polymer (polystyrene) was spin coated as thin films (<40 nm) and then dewetted under an optimal solution mixture consisting of methyl ethyl ketone, acetone and water. The carrier polymer was then selectively removed to produce the iron metal islands. These metal islands were used for selective growth of discrete patches of multiwall CNTs and CNFs by a chemical vapor deposition (CVD) process. Solvent induced dewetting showed clear advantages over thermal dewetting owing to reduced size of catalyst domains formed by dewetting, an improved control over CNT growth as well as in its ability to immobilize the seed particles. The generic solution mediated dewetting and pattern generation in thin films of various catalytic precursors can thus be a powerful method for selective domain growth of a variety of functional nanomaterials.

  20. Epitaxial thin film growth of LiH using a liquid-Li atomic template

    Energy Technology Data Exchange (ETDEWEB)

    Oguchi, Hiroyuki, E-mail: oguchi@nanosys.mech.tohoku.ac.jp [Department of Nanomechanics, Tohoku University, Sendai 980-8579 (Japan); Micro System Integration Center (muSIC), Tohoku University, Sendai 980-0845 (Japan); Ikeshoji, Tamio; Orimo, Shin-ichi [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577 (Japan); Ohsawa, Takeo; Shiraki, Susumu; Hitosugi, Taro [Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577 (Japan); Kuwano, Hiroki [Department of Nanomechanics, Tohoku University, Sendai 980-8579 (Japan)

    2014-11-24

    We report on the synthesis of lithium hydride (LiH) epitaxial thin films through the hydrogenation of a Li melt, forming abrupt LiH/MgO interface. Experimental and first-principles molecular dynamics studies reveal a comprehensive microscopic picture of the crystallization processes, which sheds light on the fundamental atomistic growth processes that have remained unknown in the vapor-liquid-solid method. We found that the periodic structure that formed, because of the liquid-Li atoms at the film/MgO-substrate interface, serves as an atomic template for the epitaxial growth of LiH crystals. In contrast, films grown on the Al{sub 2}O{sub 3} substrates indicated polycrystalline films with a LiAlO{sub 2} secondary phase. These results and the proposed growth process provide insights into the preparation of other alkaline metal hydride thin films on oxides. Further, our investigations open the way to explore fundamental physics and chemistry of metal hydrides including possible phenomena that emerge at the heterointerfaces of metal hydrides.

  1. Effect of Nano-Ni Catalyst on the Growth and Characterization of Diamond Films by HFCVD

    Directory of Open Access Journals (Sweden)

    Chien-Chung Teng

    2010-01-01

    Full Text Available Four different catalysts, nanodiamond seed, nano-Ni, diamond powder, and mixture of nano-Ni/diamond powder, were used to activate Si wafers for diamond film growth by hot-filament CVD (HFCVD. Diamond crystals were shown to grow directly on both large diamond powder and small nanodiamond seed, but a better crystallinity of diamond film was observed on the ultrasonicated nanodiamond seeded Si substrate. On the other hand, nano-Ni nanocatalysts seem to promote the formation of amorphous carbon but suppress transpolyacetylene (t-PA phases at the initial growth of diamond films. The subsequent nucleation and growth of diamond crystals on the amorphous carbon layer leads to generation of the spherical diamond particles and clusters prior to coalescence into continuous diamond films based on the CH3 addition mechanism as characterized by XRD, Raman, ATR/FT-IR, XPS, TEM, SEM, and AFM techniques. Moreover, a 36% reduction in surface roughness of diamond film assisted by nano-Ni catalyst is quite significant.

  2. Why in situ, real-time characterization of thin film growth processes?

    International Nuclear Information System (INIS)

    Auciello, O.; Krauss, A.R.

    1995-01-01

    Since thin-film growth occurs at the surface, the analytical methods should be highly surface-specific. although subsurface diffusion and chemical processes also affect film properties. Sampling depth and ambient-gas is compatibility are key factors which must be considered when choosing in situ probes of thin-film growth phenomena. In most cases, the sampling depth depends on the mean range of the exit species (ion, photon, or electron) in the sample. The techniques that are discussed in this issue of the MRS Bulletin (1) have been chosen because they may be used for in situ, real-time analysis of film-growth phenomena in vacuum and in the presence of ambient gases resulting either from the deposition process or as a requirement for the production of the desired chemical phase. A second criterion for inclusion is that the instrumentation be sufficiently compact and inexpensive to permit use as a dedicated tool in a thin-film deposition system

  3. Epitaxial thin film growth of LiH using a liquid-Li atomic template

    International Nuclear Information System (INIS)

    Oguchi, Hiroyuki; Ikeshoji, Tamio; Orimo, Shin-ichi; Ohsawa, Takeo; Shiraki, Susumu; Hitosugi, Taro; Kuwano, Hiroki

    2014-01-01

    We report on the synthesis of lithium hydride (LiH) epitaxial thin films through the hydrogenation of a Li melt, forming abrupt LiH/MgO interface. Experimental and first-principles molecular dynamics studies reveal a comprehensive microscopic picture of the crystallization processes, which sheds light on the fundamental atomistic growth processes that have remained unknown in the vapor-liquid-solid method. We found that the periodic structure that formed, because of the liquid-Li atoms at the film/MgO-substrate interface, serves as an atomic template for the epitaxial growth of LiH crystals. In contrast, films grown on the Al 2 O 3 substrates indicated polycrystalline films with a LiAlO 2 secondary phase. These results and the proposed growth process provide insights into the preparation of other alkaline metal hydride thin films on oxides. Further, our investigations open the way to explore fundamental physics and chemistry of metal hydrides including possible phenomena that emerge at the heterointerfaces of metal hydrides

  4. Synchrotron x-ray study of a low roughness and high efficiency K2CsSb photocathode during film growth

    International Nuclear Information System (INIS)

    Xie, Junqi; Demarteau, Marcel; Wagner, Robert; Schubert, Susanne; Gaowei, Mengjia; Attenkofer, Klaus; Walsh, John; Smedley, John; Ben-Zvi, Ilan; Wong, Jared; Feng, Jun; Padmore, Howard; Ruiz-Oses, Miguel; Ding, Zihao; Liang, Xue; Muller, Erik

    2017-01-01

    Reduction of roughness to the nm level is critical of achieving the ultimate performance from photocathodes used in high gradient fields. The thrust of this paper is to explore the evolution of roughness during sequential growth, and to show that deposition of multilayer structures consisting of very thin reacted layers results in an nm level smooth photocathode. Synchrotron x-ray methods were applied to study the multi-step growth process of a high efficiency K 2 CsSb photocathode. A transition point of the Sb film grown on Si was observed at the film thickness of ∼40 Å with the substrate temperature at 100 °C and the growth rate at 0.1 Å s −1 . The final K 2 CsSb photocathode exhibits a thickness of around five times that of the total deposited Sb film regardless of how the Sb film was grown. The film surface roughening process occurs first at the step when K diffuses into the crystalline Sb. The photocathode obtained from the multi-step growth exhibits roughness in an order of magnitude lower than the normal sequential process. X-ray diffraction measurements show that the material goes through two structural changes of the crystalline phase during formation, from crystalline Sb to K 3 Sb and finally to K 2 CsSb. (paper)

  5. Growth and etching characteristics of gallium oxide thin films by pulsed laser deposition

    International Nuclear Information System (INIS)

    Ou, Sin-Liang; Wuu, Dong-Sing; Fu, Yu-Chuan; Liu, Shu-Ping; Horng, Ray-Hua; Liu, Lei; Feng, Zhe-Chuan

    2012-01-01

    Highlights: ► The β-Ga2O3 thin films are prepared by pulsed laser deposition. ► The substrate temperature affects the structural, optical and etching properties of the grown films. ► The optical transmittance and band gap of the films increased with increasing the substrate temperature. ► The etching treatments for gallium oxide are performed in 49 mol% HF solution at room temperature. ► The gallium oxide thin film grown at 400 °C has the highest etching rate of 490 nm s −1 . - Abstract: The gallium oxide films were deposited on (0 0 1) sapphire at various substrate temperatures from 400 to 1000 °C by pulsed laser deposition using a KrF excimer laser. The etching treatments for as-grown gallium oxide were performed in a 49 mol% HF solution at room temperature. The structural, optical and etching properties of the grown films were investigated in terms of high resolution X-ray diffraction, optical transmittance, atomic force microscopy, and X-ray photoelectron spectroscopy. The phase transition from amorphous to polycrystalline β-Ga 2 O 3 structure was observed with increasing growth temperature. From the optical transmittance measurements, the films grown at 550–1000 °C exhibit a clear absorption edge at deep ultraviolet region around 250–275 nm wavelength. It was found that the optical band gap of gallium oxide films increased from 4.56 to 4.87 eV when the substrate temperature increased from 400 to 1000 °C. As the substrate temperature increases, the crystallinity of gallium oxide film is enhanced and the etching rate is decreased. The high etching rate of 490 nm s −1 for gallium oxide film grown at 400 °C could be due to its amorphous phase, which is referred to higher void ratio and looser atomic structure.

  6. Evaluating the Total Factor Productivity Growth in Manufacturing Industries of Iran (Data Envelopment Analysis Approach

    Directory of Open Access Journals (Sweden)

    Vahideh Ahmadi

    2014-01-01

    Full Text Available This paper examines the total factor productivity changes for 23 main manufacturing industries (2-digit ISIC group and country's provinces using data envelopment analysis during 2005 to 2007. The results show 2.3% increase in the productivity of the whole sector (average over the studied period, while the productivity of the country's provinces decreases by 7.3%, in the same period. We find Food and Beverage products and Khuzestan province having the highest productivity growth. Non-optimal allocation of resources and using of old equipments are the most important drawbacks of productivity growth for 23 main ISIC groups and provinces. Finally estimation of the regression models by panel data method reveals the privatization and increasing of labor’s available capital having a significant effect on productivity growth.

  7. How fast is the growth of Total Cross Section at High Energies?

    CERN Document Server

    Fazal-e-Aleem, M; Sohail-Afzal, Tahir; Ayub-Faridi, M; Qadee-Afzal, M

    2003-01-01

    Relativistic Heavy Ion Collider and Large Hadron Colliders have special agenda for the measurements of the total cross sections at high energies giving us an opportunity to touch cosmic ray energies. Recent analyses of the cosmic ray data together with earlier experimental measurements at ISR and SPS gives us an insight about the behaviour of this important parameter at asymptotic energies. We will study the growth of total cross section at high energies in the light of various theoretical approaches with special reference to measurements at RHIC and LHC.

  8. Growth, structural, optical and electrical study of ZnS thin films deposited by solution growth technique (SGT)

    International Nuclear Information System (INIS)

    Sadekar, H.K.; Deshpande, N.G.; Gudage, Y.G.; Ghosh, A.; Chavhan, S.D.; Gosavi, S.R.; Sharma, Ramphal

    2008-01-01

    ZnS thin films have been deposited onto glass substrates at temperature 90 deg. C by solution growth technique (SGT). The deposition parameters were optimized. Triethanolamine (TEA) was used as a complexing agent for uniform deposition of the thin films. The elemental composition of the film was confirmed by energy dispersive analysis by X-ray (EDAX) technique. Structure and surface morphology of as-deposited films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), atomic force microscopy (AFM), respectively. XRD patterns reveal that as-deposited thin films were amorphous in nature; while the obtained precipitate powder was polycrystalline in nature. SEM results revealed that deposited ZnS material has ∼120 ± 20 nm average grain size and the spherical grains are distributed over the entire glass substrate. Low surface roughness was found to be 2.7 nm from AFM studies. Transmission spectra indicate a high transmission coefficient (∼75%) with direct band gap energy equal to 3.72 eV while indirect band gap was found to be 3.45 eV. A photoluminescence (PL) study of the ZnS at room temperature (300 K) indicates a strong luminescence band at energy 2.02 eV

  9. Growth, structural, optical and electrical study of ZnS thin films deposited by solution growth technique (SGT)

    Energy Technology Data Exchange (ETDEWEB)

    Sadekar, H K [Arts, Commerce and Science college, Sonai 414105 (M.S.) (India); Thin film and Nanotechnology Laboratory, Department of Physics, Dr. B.A.M. University, Aurangabad 431004 (M.S.) (India); Deshpande, N G; Gudage, Y G; Ghosh, A; Chavhan, S D; Gosavi, S R [Thin film and Nanotechnology Laboratory, Department of Physics, Dr. B.A.M. University, Aurangabad 431004 (M.S.) (India); Sharma, Ramphal [Thin film and Nanotechnology Laboratory, Department of Physics, Dr. B.A.M. University, Aurangabad 431004 (M.S.) (India)

    2008-04-03

    ZnS thin films have been deposited onto glass substrates at temperature 90 deg. C by solution growth technique (SGT). The deposition parameters were optimized. Triethanolamine (TEA) was used as a complexing agent for uniform deposition of the thin films. The elemental composition of the film was confirmed by energy dispersive analysis by X-ray (EDAX) technique. Structure and surface morphology of as-deposited films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), atomic force microscopy (AFM), respectively. XRD patterns reveal that as-deposited thin films were amorphous in nature; while the obtained precipitate powder was polycrystalline in nature. SEM results revealed that deposited ZnS material has {approx}120 {+-} 20 nm average grain size and the spherical grains are distributed over the entire glass substrate. Low surface roughness was found to be 2.7 nm from AFM studies. Transmission spectra indicate a high transmission coefficient ({approx}75%) with direct band gap energy equal to 3.72 eV while indirect band gap was found to be 3.45 eV. A photoluminescence (PL) study of the ZnS at room temperature (300 K) indicates a strong luminescence band at energy 2.02 eV.

  10. Substrate mediated growth of organic semiconducting thin films; Templateffekte bei der Strukturierung organischer Halbleiterfilme

    Energy Technology Data Exchange (ETDEWEB)

    Goetzen, Jan

    2010-09-17

    Since electronic properties of molecular materials are closely related to their structural order a precise control of the molecular packing and crystalline orientation of thin films is of vital interest for an optimization of organic electronic devices. Of particular interest in this respect is the initial stage of film formation which is largely governed by the interplay of intermolecular and molecule-substrate interactions. One approach to control the molecular film structure is based on substrate mediated growth. In this respect we have studied structural properties of thin films of pentacene, pentacene- 5,7,12,14-tetrone and perfluoro-pentacene which were grown onto various substrates including metals, metal oxides and graphite. On metal surfaces the molecules initially form a chemisorbed monolayer where molecules even can be uniformly aligned when using appropriate substrates with twofold symmetry. Further deposition, however, is accompanied by a pronounced dewetting and formation of disjoined islands which results from a large structural mismatch between the molecular arrangement in the monolayer and the crystalline phase. In some cases it is possible to orient such islands by utilizing step mediated nucleation and decoration of step bunches which allows the preparation of azimuthally well oriented elongated islands. On single crystalline oxides the growth parallels the situation found before for SiO{sub 2} where islands of upright oriented molecules are formed. The growth on graphite is somewhat particular since the lattice provides a natural template for acenes yielding epitaxially ordered monolayer films with planar adsorption geometry like in case of metals. Interestingly, however, no dewetting occurs upon further growth and instead rather smooth films are formed. The detailed analysis for the case of pentacene showed that the substrate-molecule interaction actually is weaker than the intermolecular interaction so that multilayer films can lift the

  11. Thin film growth into the ion track structures in polyimide by atomic layer deposition

    Science.gov (United States)

    Mättö, L.; Malm, J.; Arstila, K.; Sajavaara, T.

    2017-09-01

    High-aspect ratio porous structures with controllable pore diameters and without a stiff substrate can be fabricated using the ion track technique. Atomic layer deposition is an ideal technique for depositing thin films and functional surfaces on complicated 3D structures due to the high conformality of the films. In this work, we studied Al2O3 and TiO2 films grown by ALD on pristine polyimide (Kapton HN) membranes as well as polyimide membranes etched in sodium hypochlorite (NaOCl) and boric acid (BO3) solution by means of RBS, PIXE, SEM-EDX and helium ion microcopy (HIM). The focus was on the first ALD growth cycles. The areal density of Al2O3 film in the 400 cycle sample was determined to be 51 ± 3 × 1016 at./cm2, corresponding to the thickness of 55 ± 3 nm. Furthermore, the growth per cycle was 1.4 Å/cycle. The growth is highly linear from the first cycles. In the case of TiO2, the growth per cycle is clearly slower during the first 200 cycles but then it increases significantly. The growth rate based on RBS measurements is 0.24 Å/cycle from 3 to 200 cycles and then 0.6 Å/cycle between 200 and 400 cycles. The final areal density of TiO2 film after 400 cycles is 148 ± 3 × 1015 at./cm2 which corresponds to the thickness of 17.4 ± 0.4 nm. The modification of the polyimide surface by etching prior to the deposition did not have an effect on the Al2O3 and TiO2 growth.

  12. Highly Oriented Growth of Piezoelectric Thin Films on Silicon using Two-Dimensional Nanosheets as Growth Template Layer

    NARCIS (Netherlands)

    Nguyen, Duc Minh; Yuan, H.; Houwman, Evert Pieter; Dekkers, Jan M.; Koster, Gertjan; ten Elshof, Johan E.; Rijnders, Augustinus J.H.M.

    2016-01-01

    Ca2Nb3O10 (CNOns) and Ti0.87O2 (TiOns) metal oxide nanosheets (ns) are used as a buffer layer for epitaxial growth of piezoelectric capacitor stacks on Si and Pt/Ti/SiO2/Si (Pt/Si) substrates. Highly (001)- and (110)-oriented Pb(Zr0.52Ti0.48)O3 (PZT) films are achieved by utilizing CNOns and TiOns,

  13. Growth properties of poly(tetrafluoroethylene) films by synchrotron radiation ablation

    International Nuclear Information System (INIS)

    Guo, Qixin; Kugino, Takashi; Kume, Yusuke; Mitsuishi, Yoshiaki; Tanaka, Tooru; Nishi, Mitsuhiro; Ogawa, Hiroshi

    2007-01-01

    High-quality poly(tetrafluoroethylene) (PTFE) films have been grown on Si substrates by synchrotron radiation ablation of a PTFE target. Only doublet absorption structures assigned to C-F asymmetric and symmetric stretching vibrations in CF 2 groups are observed, suggesting that the CF 2 groups in the grown PTFE film are organized in an ordered manner through linear attachment. The growth rate of the PTFE films increases with increasing target temperature, while it decreases with increasing substrate temperature. It has been shown that the thickness of the PTFE film with a high-spatial-resolution structure can be easily controlled at nanometer order by changing the synchrotron radiation irradiation dose. (author)

  14. Growth analysis of cadmium sulfide thin films by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Dhere, R.G.; Ramanathan, K. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    CdS films have been deposited by solution growth on SnO{sub 2} and glass substrates. Nucleation on SnO{sub 2} occurs at early deposition times, and complete conformal coverage is observed at low thickness values. The average grain size of the CdS films is established at these early times. In films deposited on glass substrates, nucleation is slower and occurs through 3-dimensional islands that increase in size and number as deposition proceeds. Optical measurements show that the bandgap values of CdS films deposited on SnO{sub 2} depend mainly on substrate structure. Hydrogen heat treatment does not affect the surface morphology of the samples, but decreases bandgap values.

  15. Investigation of plasma dynamics during the growth of amorphous titanium dioxide thin films

    Science.gov (United States)

    Kim, Jin-Soo; Jee, Hyeok; Yu, Young-Hun; Seo, Hye-Won

    2018-06-01

    We have grown amorphous titanium dioxide thin films by reactive DC sputtering method using a different argon/oxygen partial pressure at a room temperature. The plasma dynamics of the process, reactive and sputtered gas particles was investigated via optical emission spectroscopy. We then studied the correlations between the plasma states and the structural/optical properties of the films. The growth rate and morphology of the titanium dioxide thin films turned out to be contingent with the population and the energy profile of Ar, O, and TiO plasma. In particular, the films grown under energetic TiO plasma have shown a direct band-to-band transition with an optical energy band gap up to ∼4.2 eV.

  16. Comparative Review on Thin Film Growth of Iron-Based Superconductors

    Directory of Open Access Journals (Sweden)

    Yoshinori Imai

    2017-07-01

    Full Text Available Since the discovery of the novel iron-based superconductors, both theoretical and experimental studies have been performed intensively. Because iron-based superconductors have a smaller anisotropy than high-Tc cuprates and a high superconducting transition temperature, there have been a lot of researchers working on the film fabrication of iron-based superconductors and their application. Accordingly, many novel features have been reported in the films of iron-based superconductors, for example, the fabrication of the epitaxial film with a higher Tc than bulk samples, the extraction of the metastable phase which cannot be obtained by the conventional solid state reaction, and so on. In this paper, we review the progress of research on thin film fabrications of iron-based superconductors, especially the four categories: LnFeAs(O,F (Ln = Lanthanide, AEFe2As2 (AE = Alkaline-earth metal, FeCh (Ch = Chalcogen, and FeSe monolayer. Furthermore, we focus on two important topics in thin films of iron-based superconductors; one is the substrate material for thin film growth on the iron-based superconductors, and the other is the whole phase diagram in FeSe1-xTex which can be obtained only by using film-fabrication technique.

  17. Growth of layered superconductor β-PdBi{sub 2} films using molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, N.V., E-mail: denisov@iacp.dvo.ru [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Matetskiy, A.V.; Tupkalo, A.V. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Zotov, A.V. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation); Department of Electronics, Vladivostok State University of Economics and Service, 690600 Vladivostok (Russian Federation); Saranin, A.A. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation)

    2017-04-15

    Highlights: • Bulk β-PdBi{sub 2} is layered material with advanced properties of topological superconductor. • We present a method for growing β-PdBi{sub 2} films of a desired thickness. • Method utilizes MBE growth of β-PdBi{sub 2}, using Bi(111) film on Si(111) as a template. • Electronic and superconducting properties of the films are similar to those of bulk β-PdBi{sub 2}. - Abstract: Bulk β-PdBi{sub 2} layered material exhibits advanced properties and is supposed to be probable topological superconductor. We present a method based on molecular beam epitaxy that allows us to grow β-PdBi{sub 2} films from a single β-PdBi{sub 2} triple layer up to the dozens of triple layers, using Bi(111) film on Si(111) as a template. The grown films demonstrate structural, electronic and superconducting properties similar to those of bulk β-PdBi{sub 2} crystals. Ability to grow the β-PdBi{sub 2} films of desired thickness opens the promising possibilities to explore fascinating properties of this advanced material.

  18. Growth and characterization of ZnO thin films prepared by electrodeposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Fahoume, M.; Maghfoul, O.; Aggour, M. [L.P.M.C., Faculte des Sciences, Universite Ibn Tofail, BP. 133-14000 Kenitra (Morocco); Hartiti, B. [L.P.M.A.E.R., Faculte des Sciences et Techniques, B.P. 146 Mohammedia (Morocco); Chraibi, F.; Ennaoui, A. [L.P.M., Faculte des Sciences, Universite Mohammed V, BP.1014 Rabat (Morocco)

    2006-06-15

    ZnO thin films were deposited on either indium tin oxide-coated glass or copper substrate by the electrodeposition process, using zinc chloride and flowing air as precursors. The effect of pH on the structural and morphological ZnO films was studied and the optimum deposition conditions have been outlined. The kinetics of the growth of the films have been investigated. We note that the rate of deposition of ZnO in an acidic solution was larger than in a basic solution. The structure of the films was studied using X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The surface morphology and thickness of the films were determined using scanning electron microscopy. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure (zincite) at pH 4. The optical transmittance of ZnO decreases with varying film thickness. The optical energy bandgap was found to be 3.26eV. (author)

  19. Intrinsic stress evolution during amorphous oxide film growth on Al surfaces

    International Nuclear Information System (INIS)

    Flötotto, D.; Wang, Z. M.; Jeurgens, L. P. H.; Mittemeijer, E. J.

    2014-01-01

    The intrinsic stress evolution during formation of ultrathin amorphous oxide films on Al(111) and Al(100) surfaces by thermal oxidation at room temperature was investigated in real-time by in-situ substrate curvature measurements and detailed atomic-scale microstructural analyses. During thickening of the oxide a considerable amount of growth stresses is generated in, remarkably even amorphous, ultrathin Al 2 O 3 films. The surface orientation-dependent stress evolutions during O adsorption on the bare Al surfaces and during subsequent oxide-film growth can be interpreted as a result of (i) adsorption-induced surface stress changes and (ii) competing processes of free volume generation and structural relaxation, respectively

  20. Influence of Te and Se doping on ZnO films growth by SILAR method

    Science.gov (United States)

    Güney, Harun; Duman, Ćaǧlar

    2016-04-01

    The AIP Successive ionic layer adsorption and reaction (SILAR) is an economic and simple method to growth thin films. In this study, SILAR method is used to growth Selenium (Se) and Tellurium (Te) doped zinc oxide (ZnO) thin films with different doping rates. For characterization of the films X-ray diffraction (XRD), absorbance and scanning electron microscopy (SEM) are used. XRD results are showed well-defined strongly (002) oriented crystal structure for all samples. Also, absorbance measurements show, Te and Se concentration are proportional and inversely proportional with band gap energy, respectively. SEM measurements show that the surface morphology and thickness of the material varied with Se and/or Te and varying concentrations.

  1. Influence of Te and Se doping on ZnO films growth by SILAR method

    International Nuclear Information System (INIS)

    Güney, Harun; Duman, Çağlar

    2016-01-01

    The AIP Successive ionic layer adsorption and reaction (SILAR) is an economic and simple method to growth thin films. In this study, SILAR method is used to growth Selenium (Se) and Tellurium (Te) doped zinc oxide (ZnO) thin films with different doping rates. For characterization of the films X-ray diffraction (XRD), absorbance and scanning electron microscopy (SEM) are used. XRD results are showed well-defined strongly (002) oriented crystal structure for all samples. Also, absorbance measurements show, Te and Se concentration are proportional and inversely proportional with band gap energy, respectively. SEM measurements show that the surface morphology and thickness of the material varied with Se and/or Te and varying concentrations.

  2. Influence of Te and Se doping on ZnO films growth by SILAR method

    Energy Technology Data Exchange (ETDEWEB)

    Güney, Harun, E-mail: harunguney25@hotmail.com [Department of Electric and Energy, Vocation High School, Ağrı İbrahim Çeçen University (Turkey); Duman, Çağlar, E-mail: caglarduman@erzurum.edu.tr [Department of Electrical and Electronic Engineering, Faculty of Engineering, Erzurum Technical University (Turkey)

    2016-04-18

    The AIP Successive ionic layer adsorption and reaction (SILAR) is an economic and simple method to growth thin films. In this study, SILAR method is used to growth Selenium (Se) and Tellurium (Te) doped zinc oxide (ZnO) thin films with different doping rates. For characterization of the films X-ray diffraction (XRD), absorbance and scanning electron microscopy (SEM) are used. XRD results are showed well-defined strongly (002) oriented crystal structure for all samples. Also, absorbance measurements show, Te and Se concentration are proportional and inversely proportional with band gap energy, respectively. SEM measurements show that the surface morphology and thickness of the material varied with Se and/or Te and varying concentrations.

  3. Mechanistic Insights into Growth of Surface‐Mounted Metal‐Organic Framework Films Resolved by Infrared (Nano‐) Spectroscopy

    OpenAIRE

    Delen, Guusje; Ristanović, Zoran; Mandemaker, Laurens D. B.; Weckhuysen, Bert M.

    2017-01-01

    Abstract Control over assembly, orientation, and defect‐free growth of metal‐organic framework (MOF) films is crucial for their future applications. A layer‐by‐layer approach is considered a suitable method to synthesize highly oriented films of numerous MOF topologies, but the initial stages of the film growth remain poorly understood. Here we use a combination of infrared (IR) reflection absorption spectroscopy and atomic force microscopy (AFM)‐IR imaging to investigate the assembly and gro...

  4. MOCVD with gas phase composition control for the growth of high quality YBa2Cu3O7-x thin films for microwave applications

    International Nuclear Information System (INIS)

    Musolf, J.

    1997-01-01

    The MOCVD growth technique has demonstrated YBa 2 Cu 3 O 7-x thin films with adequate transport properties (T c >90 K, J c > x 10 6 A cm -2 , R s p /C v ) and the species concentrations. After determining the correlation between gas phase and solid phase composition this technique enables the reproducible growth of YBa 2 Cu 3 O 7-x thin films by MOCVD with composition very close to 123. Further refinement of growth temperature, total pressure, oxygen partial pressure and total flow rates has produced films with excellent properties. Smooth surface morphology with a low density of outgrowths ( 4 cm -2 ), narrow XRD rocking curve peaks FWHM c =92 K), low surface resistance (device R s <350 μΩ at 77 K, 10 GHz) have been demonstrated using this growth concept. Special focus was placed on optimization of the performance of a microwave test device which serves as a process control monitor of the suitability of these films for passive microwave applications. (orig.)

  5. Smooth Growth of Organic Semiconductor Films on Graphene for High-Efficiency Electronics

    NARCIS (Netherlands)

    Hlawacek, G.; Khokhar, F.S.; van Gastel, Raoul; Poelsema, Bene; Teichert, Christian

    2011-01-01

    High-quality thin films of conjugated molecules with smooth interfaces are important to assist the advent of organic electronics. Here, we report on the layer-by-layer growth of the organic semiconductor molecule p-sexiphenyl (6P) on the transparent electrode material graphene. Low energy electron

  6. Plasma deposition of thin film silicon at low substrate temperature and at high growth rate

    NARCIS (Netherlands)

    Verkerk, A.D.|info:eu-repo/dai/nl/304831719

    2009-01-01

    To expand the range of applications for thin film solar cells incorporating hydrogenated amorphous silicon (a-Si:H) and hydrogenated nanocrystalline silicon (nc-Si:H), the growth rate has to be increased 0.5 or less to several nm/s and the substrate temperature should be lowered to around 100 C. In

  7. Growth and characterization of Hg 1– Cd Te epitaxial films by ...

    Indian Academy of Sciences (India)

    Growth of Hg1–CdTe epitaxial films by a new technique called asymmetric vapour phase epitaxy (ASVPE) has been carried out on CdTe and CZT substrates. The critical problems faced in normal vapour phase epitaxy technique like poor surface morphology, composition gradient and dislocation multiplication have ...

  8. Plasma processes and film growth of expanding thermal plasma deposited textured zinc oxide

    NARCIS (Netherlands)

    Groenen, R.; Linden, J.L.; Sanden, van de M.C.M.

    2005-01-01

    Plasma processes and film growth of textured zinc oxide deposited from oxygen and diethyl zinc utilizing expanding thermal argon plasma created by a cascaded arc is discussed. In all conditions explored, an excess of argon ions and low temperature electrons is available, which represent the

  9. Growth and characterization of Hg1–xCdxTe epitaxial films by ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Growth of Hg1–xCdxTe epitaxial films by a new technique called asymmetric vapour phase epitaxy. (ASVPE) has been carried out on CdTe and CZT substrates. The critical problems faced in normal vapour phase epitaxy technique like poor surface morphology, composition gradient and dislocation multiplication.

  10. On the preparation and growth of a-Si:H thin films by Hg-sensitised ...

    African Journals Online (AJOL)

    It also recall and summarizes some fundamental issues such experimental systems or apparatus particularities, the analysis of gas-phase reactions in the reactor, the surface reaction model of SiH3 and H during the film growth and all the kinetic model for lamp induced Photo-CVD. Key words: Hydrogenated Amorphous ...

  11. Growth optimization and electronic structure of ultrathin CoO films on Ag(001): A LEED and photoemission study

    Science.gov (United States)

    Barman, Sukanta; Menon, Krishnakumar S. R.

    2018-04-01

    We present here a detailed growth optimization of CoO thin film on Ag(001) involving the effects of different growth parameters on the electronic structure. A well-ordered stoichiometric growth of 5 ML CoO film has been observed at 473 K substrate temperature and 1 × 10-6 mbar oxygen partial pressure. The growth at lower substrate temperature and oxygen partial pressure show non-stoichiometric impurity phases which have been investigated further to correlate the growth parameters with surface electronic structure. The coverage dependent valence band electronic structure of the films grown at optimized condition reveals the presence of interfacial states near the Fermi edge (EF) for lower film coverages. Presence of interfacial states in the stoichiometric films rules out their defect-induced origin. We argue that this is an intrinsic feature of transition metal monoxides like NiO, CoO, MnO in the low coverage regime.

  12. Mechanical properties and total hydroxycinnamic derivative release of starch/glycerol/Melissa officinalis extract films

    Directory of Open Access Journals (Sweden)

    Letícia Mello Rechia

    2010-09-01

    Full Text Available The aim of this study was to investigate the mechanical properties of starch/glycerol/Melissa officinalis, a topical drug delivery system for labial herpes treatment. Four films were prepared with different concentrations of starch, glycerol, and Melissa officinalis extract. The results revealed that increasing the glycerol concentration in the film reduced elasticity modulus and tensile strength, exhibiting a plasticizing effect. The increase in free volume resulted in increased release of hydroxycinnamic derivatives expressed as rosmarinic acid.O objetivo deste trabalho foi estudar as propriedades mecânicas e o mecanismo de liberação de um sistema tópico de liberação prolongada para o tratamento do Herpes labial a partir de filmes de amido/glicerol/extrato de Melissa officinalis, planta com comprovada atividade antiviral. Foram obtidos quatro filmes poliméricos com diferentes concentrações de amido, glicerol e extrato de Melissa officinalis os quais foram caracterizados mecanicamente e determinado o perfil de liberação de derivados hidroxicinâmicos. Os resultados demonstraram que o aumento da concentração de glicerol no filme produz uma redução no módulo de elasticidade e na tensão de deformação como conseqüência do efeito plastificante. O aumento no volume livre do polímero resultou em aumento da liberação dos derivados hidroxicinâmicos expressos como ácido rosmarínico.

  13. pH-Amplified multilayer films based on hyaluronan: influence of HA molecular weight and concentration on film growth and stability.

    Science.gov (United States)

    Shen, Liyan; Chaudouet, Patrick; Ji, Jian; Picart, Catherine

    2011-04-11

    In this study, we investigate the growth and internal properties of polyelectrolyte multilayer films made of poly(l-lysine) and hyaluronan (PLL/HA) under pH-amplified conditions, that is, by alternate deposition of PLL at high pH and HA at low pH. We focus especially on the influence of the molecular weight of HA in this process as well as on its concentration in solution. Film growth was followed by quartz crystal microbalance and by infrared spectroscopy to quantify the deposited mass and to characterize the internal properties of the films, including the presence of hydrogen bonds and the ionization degree of HA in the films. Film growth was significantly faster for HA of high molecular weight (1300 kDa) as compared with 400 and 200 kDa. PLL was found to exhibit a random structure once deposited in the films. Furthermore, we found that PLL-ending films are more stable when they are placed in PBS than their HA counterparts. This was explained on the basis of more cohesive interactions in the films for PLL-ending films. Finally, we quantified PLL(FITC) diffusion into the films and observed that PLL diffusion is enhanced when PLL is paired with the HA of high MW. All together, these results suggest that besides purely physicochemical parameters such as variation in pH, the molecular weight of HA, its concentration in solution, and the possibility to form intermolecular HA association play important roles in film growth, internal cohesion, and stability.

  14. Researching Seeds: Films, Sanitation Methods, Microbiological Growth, Viability, and Selection for New Crops

    Science.gov (United States)

    Padgett, Niki; Smith, Trent

    2018-01-01

    A major factor in long-term human exploration of the solar system is crop growth in microgravity. Space crops can provide fresh, nutritious food to supplement diets for astronauts. Important factors impacting space plant growth and consumption are water delivery to root zone in microgravity, sanitation methods for microbiological safety, plant responses to light quality/spectrum, and identifying optimal edible plants suitable for growth on the International Space Station (ISS). Astronauts growing their own food on the ISS provides necessary data for crop production for long duration deep space missions. The seed film project can be used in Advanced Plant Habitat and Veggies that are currently being utilized on the ISS.

  15. Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films

    International Nuclear Information System (INIS)

    Hees, J; Heidrich, N; Pletschen, W; Sah, R E; Wolfer, M; Lebedev, V; Nebel, C E; Ambacher, O; Williams, O A

    2013-01-01

    Unimorph heterostructures based on piezoelectric aluminum nitride (AlN) and diamond thin films are highly desirable for applications in micro- and nanoelectromechanical systems. In this paper, we present a new approach to combine thin conductive boron-doped as well as insulating nanocrystalline diamond (NCD) with sputtered AlN films without the need for any buffer layers between AlN and NCD or polishing steps. The zeta potentials of differently treated nanodiamond (ND) particles in aqueous colloids are adjusted to the zeta potential of AlN in water. Thereby, the nucleation density for the initial growth of diamond on AlN can be varied from very low (10 8 cm −2 ), in the case of hydrogen-treated ND seeding particles, to very high values of 10 11 cm −2 for oxidized ND particles. Our approach yielding high nucleation densities allows the growth of very thin NCD films on AlN with thicknesses as low as 40 nm for applications such as microelectromechanical beam resonators. Fabricated piezo-actuated micro-resonators exhibit enhanced mechanical properties due to the incorporation of boron-doped NCD films. Highly boron-doped NCD thin films which replace the metal top electrode offer Young’s moduli of more than 1000 GPa. (paper)

  16. In situ X-ray synchrotron study of organic semiconductor ultra-thin films growth

    International Nuclear Information System (INIS)

    Moulin, J.-F.; Dinelli, F.; Massi, M.; Albonetti, C.; Kshirsagar, R.; Biscarini, F.

    2006-01-01

    In this work we present an X-ray diffraction study of the early stages of growth of an organic semiconductor (sexithiophene, T 6 ) thin film prepared by high vacuum sublimation. Specular reflectometry and grazing incidence X-ray diffraction were used to monitor the formation of T 6 films on silicon oxide. Our results show that T 6 grows as a crystalline layer from the beginning of the evaporation. The reflectometry analysis suggests that, in the range of rates and temperatures studied, the growth is never layer by layer but rather 3D in nature. In-plane GIXD has allowed us to observe for the first time a thin film phase of T 6 formed of molecules standing normal to the substrate and arranged in a compressed unit cell with respect to the bulk, i.e. the unit cell parameters b and c are relatively smaller. We have followed the dynamics of formation of this new phase and identified the threshold of appearance of the bulk phase, which occurs above ∼5-6 monolayers. These results are relevant to the problem of organic thin film transistors, for which we have previously demonstrated experimentally that only the first two monolayers of T 6 films are involved in the electrical transport. The layers above the second one do not effectively contribute to charge mobility, either because they are more 'disordered' or because of a screening of the gate field

  17. Crystalline silicon thin film growth by ECR plasma CVD for solar cells

    International Nuclear Information System (INIS)

    Licai Wang

    1999-07-01

    This thesis describes the background, motivation and work carried out towards this PhD programme entitled 'Crystalline Silicon Thin Film Growth by ECR Plasma CVD for Solar Cells'. The fundamental principles of silicon solar cells are introduced with a review of silicon thin film and bulk solar cells. The development and prospects for thin film silicon solar cells are described. Some results of a modelling study on thin film single crystalline solar cells are given which has been carried out using a commercially available solar cell simulation package (PC-1D). This is followed by a description of thin film deposition techniques. These include Chemical Vapour Deposition (CVD) and Plasma-Assisted CVD (PACVD). The basic theory and technology of the emerging technique of Electron Cyclotron Resonance (ECR) PACVD, which was used in this research, are introduced and the potential advantages summarised. Some of the basic methods of material and cell characterisation are briefly described, together with the work carried out in this research. The growth by ECR PACVD at temperatures 2 illumination. The best efficiency in the ECR grown structures was 13.76% using an epitaxial emitter. Cell performance was analysed in detail and the factors controlling performance identified by fitting self-consistently the fight and dark current-voltage and spectral response data using PC-1D. Finally, the conclusions for this research and suggestions for further work are outlined. (author)

  18. Models of WO x films growth during pulsed laser deposition at elevated pressures of reactive gas

    Science.gov (United States)

    Gnedovets, A. G.; Fominski, V. Y.; Nevolin, V. N.; Romanov, R. I.; Fominski, D. V.; Soloviev, A. A.

    2017-12-01

    The films of tungsten oxides were prepared by pulsed laser ablation of W target in a reactive gas atmosphere (air of laboratory humidity). Optical analysis and ion signal measurements for the laser plume allowed to recognise a threshold gas pressure that suppresses the deposition of non-scattered atomic flux from the plume. When the pressure exceeds about 40 Pa, the films grow due to the deposition of species that could be formed in collisions of W atoms with reactive molecules (e.g., O2). Kinetic Monte Carlo method was used for modelling film growth. Comparison of the model structures with the experimentally prepared films has shown that the growth mechanism of ballistic deposition at a pressure of 40 Pa could be changed on the diffusion limited aggregation at a pressure of ~100 Pa. Thus, a cauliflower structure of the film transformed to a web-like structure. For good correlation of experimental and model structures of WO x , a dimension of structural elements in the model should coincide with W-O cluster size.

  19. Effect of enhanced C2 growth chemistry on nanodiamond film deposition

    International Nuclear Information System (INIS)

    Teii, Kungen; Ikeda, Tomohiro

    2007-01-01

    A route to high-purity nanocrystalline diamond films from C 2 dimers and related mechanisms have been investigated by enhancing C 2 growth chemistry in Ar-rich microwave plasmas. Efficient C 2 production by direct dissociation from acetylene causes the micro- to nanocrystal transition with a low threshold Ar concentration of ∼70% and produces films of ∼20 nm grains with a distinct visible-Raman peak of diamond. C 2 grows nanodiamond on diamond surfaces but rarely initiates nucleation on foreign surfaces. The phase purity can be improved by increasing the dominance of nanodiamond growth from C 2 over nondiamond growth from CH x (x=0-3) and large radicals

  20. Growth of high-quality large-area MgB2 thin films by reactive evaporation

    International Nuclear Information System (INIS)

    Moeckly, B H; Ruby, W S

    2006-01-01

    We report a new in situ reactive deposition thin film growth technique for the production of MgB 2 thin films which offers several advantages over all existing methods and is the first deposition method to enable the production of high-quality MgB 2 films for real-world applications. We have used this growth method, which incorporates a rotating pocket heater, to deposit MgB 2 films on a variety of substrates, including single-crystalline, polycrystalline, metallic, and semiconductor materials up to 4 inch in diameter. This technique allows growth of double-sided, large-area films in the intermediate temperature range of 400-600 deg. C. These films are clean, well-connected, and consistently display T c values of 38-39 K with low resistivity and residual resistivity values. They are also robust and uncommonly stable upon exposure to atmosphere and water. (rapid communication)

  1. Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

    Science.gov (United States)

    Bancroft, K; Maloney, S W; McElhaney, J; Suffet, I H; Pipes, W O

    1983-01-01

    The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study. PMID:6639023

  2. Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

    Science.gov (United States)

    Bancroft, K; Maloney, S W; McElhaney, J; Suffet, I H; Pipes, W O

    1983-09-01

    The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study.

  3. Thermodynamic analysis of growth of iron oxide films by MOCVD ...

    Indian Academy of Sciences (India)

    Abstract. Thermodynamic calculations, using the criterion of minimization of total Gibbs free energy of the system, have been carried out for the metalorganic chemical vapour deposition (MOCVD) process involving the -ketoesterate complex of iron [tris(-butyl-3-oxo-butanoato)iron(III) or Fe(tbob)3] and molecular oxygen.

  4. Substrate structure dependence of the growth modes of p-quaterphenyl thin films on gold

    International Nuclear Information System (INIS)

    Muellegger, S.; Mitsche, S.; Poelt, P.; Haenel, K.; Birkner, A.; Woell, C.; Winkler, A.

    2005-01-01

    The variably oriented crystallite surfaces of a recrystallized polycrystalline gold sample served as substrates for the investigation of the structure dependence of p-quaterphenyl (4P) thin film growth. The films were prepared in ultrahigh vacuum by organic molecular beam evaporation. Optical microscopy, scanning electron microscopy, combined with laterally resolved electron backscatter diffraction and scanning tunnelling microscopy have been applied to determine the correlation between the substrate surface structure and 4P film morphology. Crystallite surfaces consisting of (110) terraces favour highly anisotropic needle-like 4P growth with the needle orientation normal to the Au directions. Atomic steps on vicinal planes with narrow terraces (< 2 nm) can also induce anisotropy in the 4P thin film growth, in particular elongated 4P islands normal to the step direction. In contrast to that, a nearly isotropic distribution of the needle orientations is observed on Au grains terminated by highly symmetric (111) or (100) crystal planes. Additionally, patches of continuous 4P layers can be found on these surfaces. There is strong evidence that the 4P molecules within the needle-like crystallites are oriented parallel to the Au surface, whereas for the continuous layers the 4P molecules are oriented nearly upright on the surface

  5. Improvement of ZnO TCO film growth for photovoltaic devices by reactive plasma deposition (RPD)

    International Nuclear Information System (INIS)

    Iwata, K.; Sakemi, T.; Yamada, A.; Fons, P.; Awai, K.; Yamamoto, T.; Shirakata, S.; Matsubara, K.; Tampo, H.; Sakurai, K.; Ishizuka, S.; Niki, S.

    2005-01-01

    Reactive plasma deposition (RPD) is a technique for depositing a thin film on a substrate using a pressure-slope type plasma ion gun. This method offers the advantage of low-ion damage, low deposition temperature, large area deposition and high growth rates. Ga-doped zinc oxide (ZnO) thin film was grown on a moving glass substrate by RPD. Evaporation of very small quantity of tungsten from anode electrode by plasma collision lets the resistivity of grown ZnO transparent conductive oxide (TCO) film to increase. However, no reduction of carrier concentration was observed but only reduction of carrier mobility. It indicates that reduction of evaporation of tungsten from anode electrode induces increase of carrier mobility without any increase of carrier concentration. After installation of an anode cooling system in order to avoid the tungsten evaporation, increase of the mobility (37 cm 2 /Vsec) was observed and the lowest resistivity (2.0x10 -4 no. OMEGAno. cm) film was obtained from large size grown ZnO TCO of 200x200 mm at low growth temperature of 200 deg. C with high growth rate of 24 no. muno. m/h

  6. Growth of group III nitride films by pulsed electron beam deposition

    International Nuclear Information System (INIS)

    Ohta, J.; Sakurada, K.; Shih, F.-Y.; Kobayashi, A.; Fujioka, H.

    2009-01-01

    We have grown group III nitride films on Al 2 O 3 (0 0 0 1), 6H-SiC (0 0 0 1), and ZnO (0001-bar) substrates by pulsed electron beam deposition (PED) for the first time and investigated their characteristics. We found that c-plane AlN and GaN grow epitaxially on these substrates. It has been revealed that the growth of GaN on atomically flat 6H-SiC substrates starts with the three-dimensional mode and eventually changes into the two-dimensional mode. The GaN films exhibited strong near-band-edge emission in their room temperature photoluminescence spectra. We also found that the use of PED allows us to reduce the epitaxial growth temperature for GaN down to 200 deg. C. - Graphical abstract: We have grown group III nitride films by pulsed electron beam deposition (PED) and found that the films of group III nitrides grow epitaxially on 6H-SiC and Al 2 O 3 substrates. We also found that the use of PED allows us to reduce the epitaxial growth temperature for GaN down to 200 deg. C.

  7. Low hydrogen containing amorphous carbon films - Growth and electrochemical properties as lithium battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, V.; Masarapu, Charan; Wei, Bingqing [Department of Mechanical Engineering, University of Delaware, 130 Academy Street, Newark, DE 19716 (United States); Karabacak, Tansel [Department of Applied Science, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204 (United States); Teki, Ranganath [Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Lu, Toh-Ming [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2010-04-02

    Amorphous carbon films were deposited successfully on Cu foils by DC magnetron sputtering technique. Electrochemical performance of the film as lithium battery anode was evaluated across Li metal at 0.2 C rate in a non-aqueous electrolyte. The discharge curves showed unusually low irreversible capacity in the first cycle with a reversible capacity of {proportional_to}810 mAh g{sup -1}, which is at least 2 times higher than that of graphitic carbon. For the first time we report here an amorphous carbon showing such a high reversibility in the first cycle, which is very much limited to the graphitic carbon. The deposited films were extensively characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and step profilometer for the structural and surface properties. The hydrogen content of the synthesized films was studied using residual gas analysis (RGA). The low hydrogen content and the low specific surface area of the synthesized amorphous carbon film are considered responsible for such a high first cycle columbic efficiency. The growth mechanism and the reasons for enhanced electrochemical performance of the carbon films are discussed. (author)

  8. Low hydrogen containing amorphous carbon films-Growth and electrochemical properties as lithium battery anodes

    Science.gov (United States)

    Subramanian, V.; Karabacak, Tansel; Masarapu, Charan; Teki, Ranganath; Lu, Toh-Ming; Wei, Bingqing

    Amorphous carbon films were deposited successfully on Cu foils by DC magnetron sputtering technique. Electrochemical performance of the film as lithium battery anode was evaluated across Li metal at 0.2 C rate in a non-aqueous electrolyte. The discharge curves showed unusually low irreversible capacity in the first cycle with a reversible capacity of ∼810 mAh g -1, which is at least 2 times higher than that of graphitic carbon. For the first time we report here an amorphous carbon showing such a high reversibility in the first cycle, which is very much limited to the graphitic carbon. The deposited films were extensively characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and step profilometer for the structural and surface properties. The hydrogen content of the synthesized films was studied using residual gas analysis (RGA). The low hydrogen content and the low specific surface area of the synthesized amorphous carbon film are considered responsible for such a high first cycle columbic efficiency. The growth mechanism and the reasons for enhanced electrochemical performance of the carbon films are discussed.

  9. Two steps hydrothermal growth and characterisations of BaTiO3 films composed of nanowires

    Science.gov (United States)

    Zawawi, Che Zaheerah Najeehah Che Mohd; Salleh, Shahril; Oon Jew, Lee; Tufail Chaudhary, Kashif; Helmi, Mohamad; Safwan Aziz, Muhammad; Haider, Zuhaib; Ali, Jalil

    2018-05-01

    Barium titanate (BaTiO3) films composed of nanowires have gained considerable research interest due to their lead-free composition and strong energy conversion efficiency. BaTiO3 films can be developed with a simple two steps hydrothermal reactions, which are low cost effective. In this research, BaTiO3 films were fabricated on titanium foil through two steps hydrothermal method namely, the growth of TiO2 and followed by BaTiO3 films. The structural evolutions and the dielectric properties of the films were investigated as well. The structural evolutions of titanium dioxide (TiO2) and BaTiO3 nanowires were characterized using X-ray diffraction and scanning electron microscopy. First step of hydrothermal reaction, TiO2 nanowires were prepared in varied temperatures of 160 °C, 200 °C and 250 °C respectively. Second step of hydrothermal reaction was performed to produce a layer of BaTiO3 films.

  10. Effect of Substrate Morphology on Growth and Field Emission Properties of Carbon Nanotube Films

    Directory of Open Access Journals (Sweden)

    Kumar Vikram

    2008-01-01

    Full Text Available AbstractCarbon nanotube (CNT films were grown by microwave plasma-enhanced chemical vapor deposition process on four types of Si substrates: (i mirror polished, (ii catalyst patterned, (iii mechanically polished having pits of varying size and shape, and (iv electrochemically etched. Iron thin film was used as catalytic material and acetylene and ammonia as the precursors. Morphological and structural characteristics of the films were investigated by scanning and transmission electron microscopes, respectively. CNT films of different morphology such as vertically aligned, randomly oriented flowers, or honey-comb like, depending on the morphology of the Si substrates, were obtained. CNTs had sharp tip and bamboo-like internal structure irrespective of growth morphology of the films. Comparative field emission measurements showed that patterned CNT films and that with randomly oriented morphology had superior emission characteristics with threshold field as low as ~2.0 V/μm. The defective (bamboo-structure structures of CNTs have been suggested for the enhanced emission performance of randomly oriented nanotube samples.

  11. Correlation between substrate bias, growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon films

    International Nuclear Information System (INIS)

    Liu Aiping; Zhu Jiaqi; Han Jiecai; Wu Huaping; Jia Zechun

    2007-01-01

    We investigate the growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon (ta-C:P) films which are deposited at different substrate biases by filtered cathodic vacuum arc technique with PH 3 as the dopant source. The films are characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, Raman spectroscopy, residual stress measurement, UV/VIS/NIR absorption spectroscopy and temperature-dependent conductivity measurement. The atomic fraction of phosphorus in the films as a function of substrate bias is obtained by XPS analysis. The optimum bias for phosphorus incorporation is about -80 V. Raman spectra show that the amorphous structures of all samples with atomic-scaled smooth surface are not remarkably changed when PH 3 is implanted, but some small graphitic crystallites are formed. Moreover, phosphorus impurities and higher-energetic impinging ions are favorable for the clustering of sp 2 sites dispersed in sp 3 skeleton and increase the level of structural ordering for ta-C:P films, which further releases the compressive stress and enhances the conductivity of the films. Our analysis establishes an interrelationship between microstructure, stress state, electrical properties, and substrate bias, which helps to understand the deposition mechanism of ta-C:P films

  12. Composition and growth procedure-dependent properties of electrodeposited CuInSe 2 thin films

    Science.gov (United States)

    Babu, S. Moorthy; Ennaoui, A.; Lux-Steiner, M. Ch.

    2005-02-01

    CuInSe 2 thin films were deposited on molybdenum-coated glass substrates by electrodeposition. Deposition was carried out with a variety of electrochemical bath compositions. The quality of the deposits depends very much on the source materials as well as the concentration of the same in the electrolyte. The deposition potential was varied from -0.4 to -0.75 V vs. SCE. The pH of the solution was adjusted to 1.5-2 using diluted sulphuric acid. Chloride salts containing bath yield good surface morphology, but there is always excess of the metallic content in the deposited films. Different growth procedures, like initial metallic layers of copper or indium, layers of copper selenide or indium selenide before the actual deposition of ternary chalcopyrite layers were attempted. Fabrication pathway, morphological and compositional changes due to the different precursor route has been analysed. The quality of the deposits prepared by one-step electrodeposition is better than the deposits with a two-stage process. The deposited films were characterized with XRD, SEM-EDAX, UV-visible spectroscopy and I- V characteristics. The deposited films were annealed in air as well as in nitrogen atmosphere. The influence of annealing temperature, environment and annealing time on the properties of the films are evaluated. Attempts were made to fabricate solar cell structure from the deposited absorber films. The structure of Mo/CuInSe 2/CdS/ZnO/Ni was characterized with surface, optical and electrical studies.

  13. Industry Efficiency and Total Factor Productivity Growth under Resources and Environmental Constraint in China

    Science.gov (United States)

    Tao, Feng; Li, Ling; Xia, X. H.

    2012-01-01

    The growth of China's industry has been seriously depending on energy and environment. This paper attempts to apply the directional distance function and the Luenberger productivity index to measure the environmental efficiency, environmental total factor productivity, and its components at the level of subindustry in China over the period from 1999 to 2009 while considering energy consumption and emission of pollutants. This paper also empirically examines the determinants of efficiency and productivity change. The major findings are as follows. Firstly, the main sources of environmental inefficiency of China's industry are the inefficiency of gross industrial output value, the excessive energy consumption, and pollutant emissions. Secondly, the highest growth rate of environmental total factor productivity among the three industrial categories is manufacturing, followed by mining, and production and supply of electricity, gas, and water. Thirdly, foreign direct investment, capital-labor ratio, ownership structure, energy consumption structure, and environmental regulation have varying degrees of effects on the environmental efficiency and environmental total factor productivity. PMID:23365517

  14. Industry Efficiency and Total Factor Productivity Growth under Resources and Environmental Constraint in China

    Directory of Open Access Journals (Sweden)

    Feng Tao

    2012-01-01

    Full Text Available The growth of China's industry has been seriously depending on energy and environment. This paper attempts to apply the directional distance function and the Luenberger productivity index to measure the environmental efficiency, environmental total factor productivity, and its components at the level of subindustry in China over the period from 1999 to 2009 while considering energy consumption and emission of pollutants. This paper also empirically examines the determinants of efficiency and productivity change. The major findings are as follows. Firstly, the main sources of environmental inefficiency of China's industry are the inefficiency of gross industrial output value, the excessive energy consumption, and pollutant emissions. Secondly, the highest growth rate of environmental total factor productivity among the three industrial categories is manufacturing, followed by mining, and production and supply of electricity, gas, and water. Thirdly, foreign direct investment, capital-labor ratio, ownership structure, energy consumption structure, and environmental regulation have varying degrees of effects on the environmental efficiency and environmental total factor productivity.

  15. Laterally enhanced growth of electrodeposited Au to form ultrathin films on nonconductive surfaces

    International Nuclear Information System (INIS)

    Kobayashi, Chiaki; Saito, Mikiko; Homma, Takayuki

    2012-01-01

    We investigated the laterally enhanced growth of electrodeposited Au for fabricating nanogap electrodes. To enhance the lateral growth, we carried out electrodeposition over patterned electrodes onto a SiO 2 surface modified with self-assembled monolayers (SAMs) or dendrimers with amine groups. The morphology and thickness of the Au films were controlled by adjusting deposition conditions such as duration, applied potential, and Au ion concentration in the bath. To investigate the mechanism of the laterally enhanced growth, the surface states of SAM- or dendrimer-modified SiO 2 were analyzed by X-ray photoelectron spectroscopy (XPS). The XPS results indicate the existence of organic molecules and Au ions on the SiO 2 surface, which suggests that laterally enhanced growth is induced by the Au ions coordinated on the amine groups of the organic molecules. To further analyze the mechanism of the laterally enhanced growth, we investigated the relationship between the morphology of the laterally enhanced growth of Au and the amount of Au ions on organic molecules. The laterally enhanced growth of Au is expected to be useful for fabricating thin film nanogap electrodes.

  16. TiN films by Atomic Layer Deposition: Growth and electrical characterization down to sub-nm thickness

    NARCIS (Netherlands)

    Van Hao, B.; Wolters, Robertus A.M.; Kovalgin, Alexeij Y.

    2012-01-01

    This study reports on the growth and characterization of TiN thib films obtained by atomic layer deposition at 350-425 ◦C. We observe a growth of the continuous layers from the very beginning of the process, i.e. for a thickness of 0.65 nm, which is equivalent to 3 monolayers of TiN. The film growth

  17. Growth of CrTe thin films by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Sreenivasan, M.G.; Hou, X.J.; Teo, K.L.; Jalil, M.B.A.; Liew, T.; Chong, T.C.

    2006-01-01

    We report the growth of Cr 1-δ Te films on (100) GaAs substrates using ZnTe buffer layers by solid-source molecular-beam epitaxial technique. RHEED patterns indicate a clear structural change during the initial stages of deposition. Temperature-dependent magnetization results reveal that different NiAs-related phases of Cr 1-δ Te can be obtained at different substrate temperatures. By varying the film thickness, a metastable zinc blende structure of CrTe could be obtained at lower substrate temperature

  18. Growth process and structure of Er/Si(100) thin film

    International Nuclear Information System (INIS)

    Fujii, S.; Michishita, Y.; Miyamae, N.; Suto, H.; Honda, S.; Okado, H.; Oura, K.; Katayama, M.

    2006-01-01

    The solid-phase reactive epitaxial growth processes and structures of Er/Si(100) thin films were investigated by coaxial impact-collision ion scattering spectroscopy (CAICISS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-deposited Er film grown at room temperature was transformed into crystalline rectangular-shaped islands after annealing at 900 deg. C. These islands have a hexagonal AlB 2 -type structure and the epitaxial relationship is determined to be ErSi 2 (011-bar0)[0001]//Si(100)[011-bar]. It has been revealed that the surface of the Er silicide island is terminated with an Er plane

  19. Selective growth of ZnO thin film nanostructures: Structure, morphology and tunable optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Krishnakanth, Katturi Naga; Sunandana, C. S. [School of Physics, University of Hyderabad, Hyderabad-50046 (India); Rajesh, Desapogu, E-mail: rajesh.esapogu@gmail.com, E-mail: mperd@nus.edu.sg [School of Physics, University of Hyderabad, Hyderabad-50046 (India); Dept. of Mechanical Engineering, National University of Singapore (Singapore)

    2016-05-23

    The ZnO nanostructures (spherical, rod shape) have been successfully fabricated via a thermal evaporation followed by dip coating method. The pure, doped ZnO thin films were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM) and UV-Vis spectroscopy, respectively. A possible growth mechanism of the spherical, rod shape ZnO nanostructures are discussed. XRD patterns revealed that all films consist of pure ZnO phase and were well crystallized with preferential orientation towards (002) direction. Doping by PVA, PVA+Cu has effective role in the enhancement of the crystalline quality and increases in the band gap.

  20. Thin film solar cells from earth abundant materials growth and characterization of Cu2(ZnSn)(SSe)4 thin films and their solar cells

    CERN Document Server

    Kodigala, Subba Ramaiah

    2013-01-01

    The fundamental concept of the book is to explain how to make thin film solar cells from the abundant solar energy materials by low cost. The proper and optimized growth conditions are very essential while sandwiching thin films to make solar cell otherwise secondary phases play a role to undermine the working function of solar cells. The book illustrates growth and characterization of Cu2ZnSn(S1-xSex)4 thin film absorbers and their solar cells. The fabrication process of absorber layers by either vacuum or non-vacuum process is readily elaborated in the book, which helps for further developm

  1. Precipitation of thin-film organic single crystals by a novel crystal growth method using electrospray and ionic liquid film

    Science.gov (United States)

    Ueda, Hiroyuki; Takeuchi, Keita; Kikuchi, Akihiko

    2018-04-01

    We report an organic single crystal growth technique, which uses a nonvolatile liquid thin film as a crystal growth field and supplies fine droplets containing solute from the surface of the liquid thin film uniformly and continuously by electrospray deposition. Here, we investigated the relationships between the solute concentration of the supplied solution and the morphology and size of precipitated crystals for four types of fluorescent organic low molecule material [tris(8-hydroxyquinoline)aluminum (Alq3), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), N,N‧-bis(3-methylphenyl)-N,N‧-diphenylbenzidine (TPD), and N,N-bis(naphthalene-1-yl)-N,N-diphenyl-benzidine (NPB)] using an ionic liquid as the nonvolatile liquid. As the concentration of the supplied solution decreased, the morphology of precipitated crystals changed from dendritic or leaf shape to platelike one. At the solution concentration of 0.1 mg/ml, relatively large platelike single crystals with a diagonal length of over 100 µm were obtained for all types of material. In the experiment using ionic liquid and dioctyl sebacate as nonvolatile liquids, it was confirmed that there is a clear positive correlation between the maximum volume of the precipitated single crystal and the solubility of solute under the same solution supply conditions.

  2. In situ growth of p and n-type graphene thin films and diodes by pulsed laser deposition

    KAUST Repository

    Sarath Kumar, S. R.

    2013-11-07

    We report the in situ growth of p and n-type graphene thin films by ultraviolet pulsed laser deposition in the presence of argon and nitrogen, respectively. Electron microscopy and Raman studies confirmed the growth, while temperature dependent electrical conductivity and Seebeck coefficient studies confirmed the polarity type of graphene films. Nitrogen doping at different sites of the honeycomb structure, responsible for n-type conduction, is identified using X-ray photoelectron spectroscopy, for films grown in nitrogen. A diode-like rectifying behavior is exhibited by p-n junction diodes fabricated using the graphene films.

  3. Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Bakoglidis, Konstantinos D., E-mail: konba@ifm.liu.se; Schmidt, Susann; Garbrecht, Magnus; Ivanov, Ivan G.; Jensen, Jens; Greczynski, Grzegorz; Hultman, Lars [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden)

    2015-09-15

    The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CN{sub x}) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CN{sub x} films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N{sub 2}/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage, V{sub s}, was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at V{sub s} ≥ 60 V, V{sub s} ≥ 100 V, and V{sub s} = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of V{sub s} for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all V{sub s}, while CN{sub x} films deposited by MFMS showed residual stresses up to −4.2

  4. Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering

    International Nuclear Information System (INIS)

    Bakoglidis, Konstantinos D.; Schmidt, Susann; Garbrecht, Magnus; Ivanov, Ivan G.; Jensen, Jens; Greczynski, Grzegorz; Hultman, Lars

    2015-01-01

    The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CN x ) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CN x films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N 2 /Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage, V s , was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at V s  ≥ 60 V, V s  ≥ 100 V, and V s  = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of V s for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all V s , while CN x films deposited by MFMS showed residual stresses up to −4.2 GPa. Nanoindentation showed a significant

  5. TTF/TCNQ-based thin films and microcrystals. Growth and charge transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Solovyeva, Vita

    2011-05-26

    The thesis adresses several problems related to growth and charge transport phenomena in thin films of TTF-TCNQ and (BEDT-TTF)TCNQ. The following main new problems are addressed: - The influence of thin-film specific factors, such as the substrate material and growth-induced defects, on the Peierls transition temperature in TTF-TCNQ thin films was studied; - finite-size effects in TTF-TCNQ were investigated by considering transport properties in TTF-TCNQ microcrystals. The influence of the size of the crystal on the Peierls transition temperature was studied. In this context a new method of microcontact fabrication was employed to favor the measurements; - an analysis of radiation-induced defects in TTF-TCNQ thin films and microcrystals was performed. It was demonstrated than an electron beam can induce appreciable damage to the sample such that its electronic properties are strongly modified; - a bilayer growth method was established to fabricate (BEDT-TTF)TCNQ from the gas phase. This newly developed bilayer growth method was showed to be suitable for testing (BEDT-TTF)TCNQ charge-transfer phase formation; - the structure of the formed (BEDT-TTF)TCNQ charge-transfer compounds was analyzed by using a wide range of experimental techniques. An overview and the description of the basic physical principles underlying charge-transfer compounds is given in chapter 2. Experimental techniques used for the growth and characterization of thin films and microcrystals are presented in chapter 3. Chapter 4 gives an overview of the physical properties of the studied organic materials. Chapter 5 discussed the experimental study of TTF-TCNQ thin films. he Peierls transition in TTF-TCNQ is a consequence of the quasi-one-dimensional structure of the material and depends on different factors, studied in chapters 5 and 6. In contradistinction to TTF-TTCNQ, the (BEDT-TTF)TCNQ charge-transfer compound crystallizes in several different modifications with different physical properties

  6. The growth of large-area superconducting YBa2Cu3O7-x thin films by pulsed laser ablation

    International Nuclear Information System (INIS)

    Lai, H.C.; Chang, C.M.; Lin, R.J.; Liu, R.S.

    1996-01-01

    In-situ growth of 2-in. diameter superconducting YBa 2 Cu 3 O 7-x (YBCO) thin films using an excimer KrF pulsed laser has been studied. Films with critical transition temperature (T c,0 ) of 89±1 K and critical current density (J c,77K ) in excess of 1 x 10 6 A cm -2 have been prepared routinely. Uniformity in film thickness of below ±15% and film composition of ±5% have been measured. The effects of gas nozzle geometry and target evolution during ablation on the superconducting properties and surface morphology of YBCO thin films have also been investigated. (orig.)

  7. Amorphous-tetrahedral diamondlike carbon layered structures resulting from film growth energetics

    Science.gov (United States)

    Siegal, M. P.; Barbour, J. C.; Provencio, P. N.; Tallant, D. R.; Friedmann, T. A.

    1998-08-01

    High-resolution transmission electron microscopy (HRTEM) shows that amorphous-tetrahedral diamondlike carbon (a-tC) films grown by pulsed-laser deposition on Si(100) consist of three-to-four layers, depending on the growth energetics. We estimate the density of each layer using both HRTEM image contrast and Rutherford backscattering spectrometry. The first carbon layer and final surface layer have relatively low density. The bulk of the film between these two layers has higher density. For films grown under the most energetic conditions, there exists a superdense a-tC layer between the interface and bulk layers. The density of all four layers, and the thickness of the surface and interfacial layers, correlate well with the energetics of the depositing carbon species.

  8. Chemical vapor deposition polymerization the growth and properties of parylene thin films

    CERN Document Server

    Fortin, Jeffrey B

    2004-01-01

    Chemical Vapor Deposition Polymerization - The Growth and Properties of Parylene Thin Films is intended to be valuable to both users and researchers of parylene thin films. It should be particularly useful for those setting up and characterizing their first research deposition system. It provides a good picture of the deposition process and equipment, as well as information on system-to-system variations that is important to consider when designing a deposition system or making modifications to an existing one. Also included are methods to characterizae a deposition system's pumping properties as well as monitor the deposition process via mass spectrometry. There are many references that will lead the reader to further information on the topic being discussed. This text should serve as a useful reference source and handbook for scientists and engineers interested in depositing high quality parylene thin films.

  9. Heteroepitaxial Growth of Vacuum-Evaporated Si-Ge Films on Nano structured Silicon Substrates

    International Nuclear Information System (INIS)

    Ayu Wazira Azhari; Ayu Wazira Azhari; Kamaruzzaman Sopian; Saleem Hussain Zaidi

    2015-01-01

    In this study, a low-cost vacuum-evaporated technique is used in the heteroepitaxial growth of Si-Ge films. Three different surface variations are employed: for example polished Si, Si micro pyramids and Si nano pillars profiles. A simple metal-assisted chemical etching method is used to fabricate the Si nano pillars, with Ag acting as a catalyst. Following deposition, substrates are subjected to post-deposition thermal annealing at 1000 degree Celsius to improve the crystallinity of the Ge layer. Optical and morphological studies of surface area are conducted using field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray (EDX), Raman spectroscopy and infrared spectroscopy. From the infrared spectroscopy analysis, the energy bandgap for Si-Ge films is estimated to be around 0.94 eV. This high-quality Si-Ge film is most favourable for optics, optoelectronics and high-efficiency solar cell applications. (author)

  10. Numerical Simulation of Vapor Bubble Growth and Heat Transfer in a Thin Liquid Film

    International Nuclear Information System (INIS)

    Yu-Jia, Tao; Xiu-Lan, Huai; Zhi-Gang, Li

    2009-01-01

    A mathematical model is developed to investigate the dynamics of vapor bubble growth in a thin liquid film, movement of the interface between two fluids and the surface heat transfer characteristics. The model takes into account the effects of phase change between the vapor and liquid, gravity, surface tension and viscosity. The details of the multiphase now and heat transfer are discussed for two cases: (1) when a water micro-droplet impacts a thin liquid film with a vapor bubble growing and (2) when the vapor bubble grows and merges with the vapor layer above the liquid film without the droplet impacting. The development trend of the interface between the vapor and liquid is coincident qualitatively with the available literature, mostly at the first stage. We also provide an important method to better understand the mechanism of nucleate spray cooling. (fundamental areas of phenomenology (including applications))

  11. High growth rate of a-SiC:H films using ethane carbon source by HW

    Indian Academy of Sciences (India)

    Hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared ... Total hydrogen content drops from 22.6 to 14.4 at.% when deposition pressure is increased. Raman spectra show increase in structural disorder with increase in ...

  12. Effects of local film properties on the nucleation and growth of tin whiskers and hillocks

    Science.gov (United States)

    Sarobol, Pylin

    Whiskers and hillocks grow spontaneously on Pb-free Sn electrodeposited films as a response to thin film stresses. Stress relaxation occurs by atom deposition to specific grain boundaries in the plane of the film, with hillocks being formed when grain boundary migration accompanies growth out of the plane of the film. The implication for whisker formation in electronics is serious: whiskers can grow to be millimeters long, sometimes causing short circuiting between adjacent components and, thereby, posing serious electrical reliability risks. In order to develop more effective whisker mitigation strategies, a predictive physics-based model has been needed. A growth model is developed, based on grain boundary faceting, localized Coble creep, as well as grain boundary sliding for whiskers, and grain boundary sliding with shear induced grain boundary migration for hillocks. In this model of whisker formation, two mechanisms are important: accretion of atoms by Coble creep on grain boundary planes normal to the growth direction inducing a grain boundary shear and grain boundary sliding in the direction of whisker growth. The model accurately captures the importance of the geometry of "surface grains"---shallow grains on film surfaces whose depths are significantly less than their in-plane grain sizes. A critical factor in the analysis is the ratio of the grain boundary sliding coefficient to the in-plane film compressive stress. If the accretion-induced shear stresses are not coupled to grain boundary motion and sliding occurs, a whisker forms. If the shear stress is coupled to grain boundary migration, a hillock forms. Based on this model, long whiskers grow from shallow surface grains with easy grain boundary sliding in the direction of growth. Other observed growth morphologies will be discussed in light of our model. Additional insights into the preferred sites for whisker and hillock growth were developed based on elastic anisotropy, local film microstructure

  13. Vanadium and molybdenum oxide thin films on Au(111). Growth and surface characterization

    Energy Technology Data Exchange (ETDEWEB)

    Guimond, Sebastien

    2009-06-04

    The growth and the surface structure of well-ordered V{sub 2}O{sub 3}, V{sub 2}O{sub 5} and MoO{sub 3} thin films have been investigated in this work. These films are seen as model systems for the study of elementary reaction steps occurring on vanadia and molybdena-based selective oxidation catalysts. It is shown that well-ordered V{sub 2}O{sub 3}(0001) thin films can be prepared on Au(111). The films are terminated by vanadyl groups which are not part of the V{sub 2}O{sub 3} bulk structure. Electron irradiation specifically removes the oxygen atoms of the vanadyl groups, resulting in a V-terminated surface. The fraction of removed vanadyl groups is controlled by the electron dose. Such surfaces constitute interesting models to probe the relative role of both the vanadyl groups and the undercoordinated V ions at the surface of vanadia catalysts. The growth of well-ordered V{sub 2}O{sub 5}(001) and MoO{sub 3}(010) thin films containing few point defects is reported here for the first time. These films were grown on Au(111) by oxidation under 50 mbar O{sub 2} in a dedicated high pressure cell. Contrary to some of the results found in the literature, the films are not easily reduced by annealing in UHV. This evidences the contribution of radiation and surface contamination in some of the reported thermal reduction experiments. The growth of ultrathin V{sub 2}O{sub 5} and MoO{sub 3} layers on Au(111) results in formation of interface-specific monolayer structures. These layers are coincidence lattices and they do not correspond to any known oxide bulk structure. They are assumed to be stabilized by electronic interaction with Au(111). Their formation illustrates the polymorphic character and the ease of coordination units rearrangement which are characteristic of both oxides. The formation of a second layer apparently precedes the growth of bulk-like crystallites for both oxides. This observation is at odds with a common assumption that crystals nucleate as soon as a

  14. Vanadium and molybdenum oxide thin films on Au(111). Growth and surface characterization

    International Nuclear Information System (INIS)

    Guimond, Sebastien

    2009-01-01

    The growth and the surface structure of well-ordered V 2 O 3 , V 2 O 5 and MoO 3 thin films have been investigated in this work. These films are seen as model systems for the study of elementary reaction steps occurring on vanadia and molybdena-based selective oxidation catalysts. It is shown that well-ordered V 2 O 3 (0001) thin films can be prepared on Au(111). The films are terminated by vanadyl groups which are not part of the V 2 O 3 bulk structure. Electron irradiation specifically removes the oxygen atoms of the vanadyl groups, resulting in a V-terminated surface. The fraction of removed vanadyl groups is controlled by the electron dose. Such surfaces constitute interesting models to probe the relative role of both the vanadyl groups and the undercoordinated V ions at the surface of vanadia catalysts. The growth of well-ordered V 2 O 5 (001) and MoO 3 (010) thin films containing few point defects is reported here for the first time. These films were grown on Au(111) by oxidation under 50 mbar O 2 in a dedicated high pressure cell. Contrary to some of the results found in the literature, the films are not easily reduced by annealing in UHV. This evidences the contribution of radiation and surface contamination in some of the reported thermal reduction experiments. The growth of ultrathin V 2 O 5 and MoO 3 layers on Au(111) results in formation of interface-specific monolayer structures. These layers are coincidence lattices and they do not correspond to any known oxide bulk structure. They are assumed to be stabilized by electronic interaction with Au(111). Their formation illustrates the polymorphic character and the ease of coordination units rearrangement which are characteristic of both oxides. The formation of a second layer apparently precedes the growth of bulk-like crystallites for both oxides. This observation is at odds with a common assumption that crystals nucleate as soon as a monolayer is formed dur-ing the preparation of supported vanadia

  15. Controllable growth and characterization of highly aligned ZnO nanocolumnar thin films

    Energy Technology Data Exchange (ETDEWEB)

    Onuk, Zuhal [Department of Physics, Recep Tayyip Erdogan University, Rize, 53100 (Turkey); Department of Materials Science and Engineering, University of Delaware, Newark, DE, 19716 (United States); Rujisamphan, Nopporn [Nanoscience and Nanotechnology Graduate Program, Faculty of Science, King Mongkut’s University of Technology Thonburi, 10140, Bangkok (Thailand); Theoretical and Computational Science Center (TaCS), Faculty of Science, King Mongkut’s University of Technology Thonburi, Bangkok 10140 (Thailand); Murray, Roy [Department of Physics and Astronomy, University of Delaware, Newark, DE, 19716 (United States); Bah, Mohamed [Department of Materials Science and Engineering, University of Delaware, Newark, DE, 19716 (United States); Tomakin, Murat [Department of Physics, Recep Tayyip Erdogan University, Rize, 53100 (Turkey); Shah, S.Ismat, E-mail: ismat@udel.edu [Department of Materials Science and Engineering, University of Delaware, Newark, DE, 19716 (United States); Department of Physics and Astronomy, University of Delaware, Newark, DE, 19716 (United States)

    2017-02-28

    Graphical abstract: Scanning electron micrographs of the top view surfaces (left column) and cross sections of sputtered ZnO thin films prepared at various Ar:O{sub 2} ratios: (a) and (b) 10:0, (c) and (d) 7.5:2.5, (e) and (f) 5:5, (g) and (h) 2.5:7.5. - Highlights: • Nanocolumnar ZnO films were prepared by controlling the argon-oxygen sputtering gas ratio. • Oxygen partial pressure affects the band gap alignment of the ZnO films. • Optical transmission spectroscopy and XPS were used to study band gap shifts. - Abstract: We investigated the effects of growth conditions during magnetron sputtering on the structural, morphological, and optical properties of nanostructured ZnO thin films. Undoped ZnO thin films are deposited onto p-type Si (100) and corning 7059 glass substrates by RF magnetron sputtering using a ZnO target in combination with various Ar-O{sub 2} sputtering gas mixtures at room temperature. The effect of the partial pressure of oxygen on the morphology of ZnO thin film structure and band alignment were investigated. Thickness, and therefore the growth rate of the samples measured from the cross-sectional SEM micrographs, is found to be strongly correlated with the oxygen partial pressure in the sputtering chamber. The optical transmittance spectrometry results show that the absorption edge shifts towards the longer wavelength at higher oxygen partial pressure. X-ray photoelectron spectroscopy (XPS) used for determining the surface chemical structure and valence band offsets show that conduction band can be controlled by changing the sputtering atmosphere.

  16. Controlled Growth of Ultrathin Film of Organic Semiconductors by Balancing the Competitive Processes in Dip-Coating for Organic Transistors.

    Science.gov (United States)

    Wu, Kunjie; Li, Hongwei; Li, Liqiang; Zhang, Suna; Chen, Xiaosong; Xu, Zeyang; Zhang, Xi; Hu, Wenping; Chi, Lifeng; Gao, Xike; Meng, Yancheng

    2016-06-28

    Ultrathin film with thickness below 15 nm of organic semiconductors provides excellent platform for some fundamental research and practical applications in the field of organic electronics. However, it is quite challenging to develop a general principle for the growth of uniform and continuous ultrathin film over large area. Dip-coating is a useful technique to prepare diverse structures of organic semiconductors, but the assembly of organic semiconductors in dip-coating is quite complicated, and there are no reports about the core rules for the growth of ultrathin film via dip-coating until now. In this work, we develop a general strategy for the growth of ultrathin film of organic semiconductor via dip-coating, which provides a relatively facile model to analyze the growth behavior. The balance between the three direct factors (nucleation rate, assembly rate, and recession rate) is the key to determine the growth of ultrathin film. Under the direction of this rule, ultrathin films of four organic semiconductors are obtained. The field-effect transistors constructed on the ultrathin film show good field-effect property. This work provides a general principle and systematic guideline to prepare ultrathin film of organic semiconductors via dip-coating, which would be highly meaningful for organic electronics as well as for the assembly of other materials via solution processes.

  17. The influence of energetic bombardment on the structure formation of sputtered zinc oxide films. Development of an atomistic growth model and its application to tailor thin film properties

    Energy Technology Data Exchange (ETDEWEB)

    Koehl, Dominik

    2011-02-17

    The focus of this work is the investigation of the growth of zinc oxide (ZnO) thin films. It is demonstrated that with a modified, ion beam assisted sputtering (IBAS) process, zinc oxide films can be deposited which exhibit a markedly improved crystalline order. Furthermore, it is demonstrated that intense energetic oxygen ion bombardment can be utilized to change film texture from the typical (002)-self-texture to an a-axis texture where the (002)-planes are perpendicular to the substrate surface. An understanding of the underlying mechanisms is developed which also facilitates a more detailed understanding of the action of ion bombardment during zinc oxide film growth. It is shown that zinc oxide films are susceptible to the influence of ion bombardment particularly in the nucleation regime of growth and that this finding is generally true for all observed structural changes induced by ion bombardment with various species, energies and flux densities. It is demonstrated not only that the initial growth stage plays an important role in the formation of a preferred growth orientation but also that the action of texture forming mechanisms in subsequent growth stages is comparatively weak. (orig.)

  18. The influence of energetic bombardment on the structure formation of sputtered zinc oxide films. Development of an atomistic growth model and its application to tailor thin film properties

    International Nuclear Information System (INIS)

    Koehl, Dominik

    2011-01-01

    The focus of this work is the investigation of the growth of zinc oxide (ZnO) thin films. It is demonstrated that with a modified, ion beam assisted sputtering (IBAS) process, zinc oxide films can be deposited which exhibit a markedly improved crystalline order. Furthermore, it is demonstrated that intense energetic oxygen ion bombardment can be utilized to change film texture from the typical (002)-self-texture to an a-axis texture where the (002)-planes are perpendicular to the substrate surface. An understanding of the underlying mechanisms is developed which also facilitates a more detailed understanding of the action of ion bombardment during zinc oxide film growth. It is shown that zinc oxide films are susceptible to the influence of ion bombardment particularly in the nucleation regime of growth and that this finding is generally true for all observed structural changes induced by ion bombardment with various species, energies and flux densities. It is demonstrated not only that the initial growth stage plays an important role in the formation of a preferred growth orientation but also that the action of texture forming mechanisms in subsequent growth stages is comparatively weak. (orig.)

  19. Growth of carbon fibres, sheets and tubes on diamond films under high power plasma etching conditions

    Energy Technology Data Exchange (ETDEWEB)

    Villalpando, I. [Centro de Investigacion de los Recursos Naturales, Antigua Normal Rural, Salaices, Lopez, Chihuahua (Mexico); John, P.; Wilson, J. I. B., E-mail: isaelav@hotmail.com [School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14-4AS (United Kingdom)

    2017-11-01

    The application of diamond as a plasma facing material for fusion reactors can be limited by unknown reactions between diamond and the chamber materials transported by the plasma. Transformation of diamond to other structures can cause problems such as contamination of the plasma with loose particles or retention of gases. We have seen that diamond thin films are eroded under hydrogen plasma etching, but if silicon is present the growth of various carbon structures on diamond films is observed. We have produced carbon with different morphologies on diamond films including fibres, sheets with flower-like shapes and tubes and proposed growth mechanisms based on the results of scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Sample surfaces contain silicon and are oxidised having COO and CO groups as seen by XP S analysis. Raman analyses revealed a spectrum typical for graphite combined with that from diamond that remains on the surface after hydrogen bombardment. The results of this sturdy show the experimental conditions in which carbon fibres, sheets and tubes are produced under high-power hydrogen etching of diamond films and open the possibility to other applications such as catalysts, sensors and the production of electrodes. (Author)

  20. Direct observation of atomic-level nucleation and growth processes from an ultrathin metallic glass films

    Energy Technology Data Exchange (ETDEWEB)

    Huang, K. Q.; Cao, C. R.; Sun, Y. T.; Li, J.; Bai, H. Y.; Zheng, D. N., E-mail: l.gu@iphy.ac.cn, E-mail: dzheng@iphy.ac.cn, E-mail: whw@iphy.ac.cn; Wang, W. H., E-mail: l.gu@iphy.ac.cn, E-mail: dzheng@iphy.ac.cn, E-mail: whw@iphy.ac.cn [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Gu, L., E-mail: l.gu@iphy.ac.cn, E-mail: dzheng@iphy.ac.cn, E-mail: whw@iphy.ac.cn [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

    2016-01-07

    Till date, there have been no direct atomic-level experimental observations of the earliest stages of the nucleation and growth processes of nanocrystals formed by thermally induced crystallization in ultrathin metallic glasses (MGs). Here, we present a study of the crystallization process in atomically thin and highly stable MG films using double spherical aberration-corrected scanning transmission electron microscopy (Cs-TEM). Taking advantage of the stability of MG films with a slow crystallization process and the atomic-level high resolution of Cs-TEM, we observe the formation of the nucleus precursor of nanocrystals formed by atom aggregation followed by concomitant coalescence and stepwise evolution of the shape of the nanocrystals with a monodispersed and separated bimodal size distribution. Molecular dynamics simulation of the atomic motion in the glass film on a rigid amorphous substrate confirms the stepwise evolution processes of atom aggregation, cluster formation, cluster movement on the substrate, and cluster coalescence into larger crystalline particles. Our results might provide a better fundamental understanding of the nucleation and growth processes of nanocrystals in thin MG films.

  1. The effects of varying plasma parameters on silicon thin film growth by ECR plasma CVD

    International Nuclear Information System (INIS)

    Summers, S.; Reehal, H.S.; Shirkoohi, G.H.

    2001-01-01

    The technique of electron cyclotron resonance (ECR) plasma enhanced chemical vapour deposition (PECVD) is increasingly being used in electronic and photonic device applications. ECR offers a number of advantages including improved control of the deposition process, less damage to the growing film and the possibility of high deposition rates. ECR occurs in a plasma under appropriate magnetic and electric field conditions. In most cases, as in our system, this is achieved with a combination of 2.45 GHz microwave radiation and a 0.0875 T magnetic field, due to the use of standardized microwave supplies. We have studied the effects on silicon film growth of changing the magnetic field configuration to produce one or more planes of ECR within the system, and of changing the positions of the plane(s) relative to the deposition substrate. The films were grown in silane-hydrogen discharges. The magnetic field in our system was provided by two electromagnets. It was measured experimentally for a number of operating current values and then a detailed profile achieved by modelling using a proprietary software package. A process condition discharge under identical magnetic field configurations to growth was analysed by the use of a Langmuir probe and the results correlated with film properties determined by Raman spectroscopy and Dektak profilometry. (author)

  2. Growth of carbon fibres, sheets and tubes on diamond films under high power plasma etching conditions

    International Nuclear Information System (INIS)

    Villalpando, I.; John, P.; Wilson, J. I. B.

    2017-01-01

    The application of diamond as a plasma facing material for fusion reactors can be limited by unknown reactions between diamond and the chamber materials transported by the plasma. Transformation of diamond to other structures can cause problems such as contamination of the plasma with loose particles or retention of gases. We have seen that diamond thin films are eroded under hydrogen plasma etching, but if silicon is present the growth of various carbon structures on diamond films is observed. We have produced carbon with different morphologies on diamond films including fibres, sheets with flower-like shapes and tubes and proposed growth mechanisms based on the results of scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Sample surfaces contain silicon and are oxidised having COO and CO groups as seen by XP S analysis. Raman analyses revealed a spectrum typical for graphite combined with that from diamond that remains on the surface after hydrogen bombardment. The results of this sturdy show the experimental conditions in which carbon fibres, sheets and tubes are produced under high-power hydrogen etching of diamond films and open the possibility to other applications such as catalysts, sensors and the production of electrodes. (Author)

  3. Growth of Sr2CrReO6 epitaxial thin films by pulsed laser deposition

    International Nuclear Information System (INIS)

    Orna, J.; Morellon, L.; Algarabel, P.A.; Pardo, J.A.; Magen, C.; Varela, M.; Pennycook, S.J.; De Teresa, J.M.; Ibarra, M.R.

    2010-01-01

    We report the growth, structural, magnetic, and electrical transport properties of epitaxial Sr 2 CrReO 6 thin films. We have succeeded in depositing films with a high crystallinity and a relatively large cationic order in a narrow window of growth parameters. The epitaxy relationship is Sr 2 CrReO 6 (SCRO) (0 0 1) [1 0 0]-parallel SrTiO 3 (STO) (0 0 1) [1 1 0] as determined by high-resolution X-ray diffraction and scanning transmission electron microscopy (STEM). Typical values of saturation magnetization of M S (300 K)=1 μ B /f.u. and ρ (300 K)=2.8 mΩ cm have been obtained in good agreement with previous published results in sputtered epitaxial thin films. We estimate that the antisite defects concentration in our thin films is of the order of 14%, and the measured Curie temperature is T C =481(2) K. We believe these materials be of interest as electrodes in spintronic devices.

  4. Growth dependent magnetization reversal in Co2MnAl full Heusler alloy thin films

    Science.gov (United States)

    Barwal, Vineet; Husain, Sajid; Behera, Nilamani; Goyat, Ekta; Chaudhary, Sujeet

    2018-02-01

    Angular dependent magnetization reversal has been investigated in Co2MnAl (CMA) full Heusler alloy thin films grown on Si(100) at different growth temperatures (Ts) by DC-magnetron sputtering. An M -shaped curve is observed in the in-plane angular (0°-360°) dependent coercivity (ADC) by magneto-optical Kerr effect measurements. The dependence of the magnetization reversal on Ts is investigated in detail to bring out the structure-property correlation with regards to ADC in these polycrystalline CMA thin films. This magnetization reversal ( M -shaped ADC behavior) is well described by the two-phase model, which is a combination of Kondorsky (domain wall motion) and Stoner Wohlfarth (coherent rotation) models. In this model, magnetization reversal starts with depinning of domain walls, with their gradual displacement explained by the Kondorsky model, and at a higher field (when the domain walls merge), the system follows coherent rotation before reaching its saturation following the Stoner Wohlfarth model. Further, the analysis of angular dependent squareness ratio (Mr/Ms) indicates that our films clearly exhibited twofold uniaxial anisotropy, which is related to self-steering effect arising due to the obliquely incident flux during the film-growth.

  5. Underpotential deposition-mediated layer-by-layer growth of thin films

    Science.gov (United States)

    Wang, Jia Xu; Adzic, Radoslav R.

    2015-05-19

    A method of depositing contiguous, conformal submonolayer-to-multilayer thin films with atomic-level control is described. The process involves the use of underpotential deposition of a first element to mediate the growth of a second material by overpotential deposition. Deposition occurs between a potential positive to the bulk deposition potential for the mediating element where a full monolayer of mediating element forms, and a potential which is less than, or only slightly greater than, the bulk deposition potential of the material to be deposited. By cycling the applied voltage between the bulk deposition potential for the mediating element and the material to be deposited, repeated desorption/adsorption of the mediating element during each potential cycle can be used to precisely control film growth on a layer-by-layer basis. This process is especially suitable for the formation of a catalytically active layer on core-shell particles for use in energy conversion devices such as fuel cells.

  6. Multiple oxide content media for columnar grain growth in L10 FePt thin films

    International Nuclear Information System (INIS)

    Ho, Hoan; Yang, En; Laughlin, David E.; Zhu, Jian-Gang

    2013-01-01

    An approach to enhance the height-to-diameter ratio of FePt grains in heat-assisted magnetic recording media is proposed. The FePt-SiO x thin films are deposited with a decrease of the SiO x percentage along the film growth direction. When bi-layer and tri-layer media are sputtered at 410 °C, we observe discontinuities in the FePt grains at interfaces between layers, which lead to poor epitaxial growth. Due to increased atomic diffusion, the bi-layer media sputtered at 450 °C is shown to (1) grow into continuous columnar grains with similar size as single-layer media but much higher aspect ratio, (2) have better L1 0 ordering and larger coercivity.

  7. Properties of dislocations in Cu(In,Ga)Se2 film and their formation during growth

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Jens; Boit, Christian [Technische Universitaet Berlin, Department of Semiconductor Devices, Einsteinufer 19, 10587 Berlin (Germany); Abou-Ras, Daniel; Rissom, Thorsten; Unold, Thomas; Schock, Hans-Werner [Helmholtz Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Niermann, Tore; Lehmann, Michael [Technische Universitaet Berlin, Institute of Optics and Atomic Physics, Hardenbergstrasse 36, 10623 Berlin (Germany)

    2012-07-01

    Transmission electron microscopy (TEM) studies were performed on Cu(In,Ga)Se2 (CIGSe) thin films for solar cells with a special focus on dislocations. A sample series of glass/Mo/CIGSe stacks with varying [Cu]/([Ga]+[In]) ratio were prepared by interrupting the growth processes at several stages. TEM imaging and elemental distribution maps by energy-dispersive X-ray spectroscopy gave structural and compositional information at certain film growth states. Furthermore, high resolution TEM imaging was used to confirm a structural model of dislocations in complete CIGSe solar cells and by means of in-line electron holography we examined changes in the mean inner potential. A decrease of the mean inner potential at the position of the dislocations was observed. This might be attributed to a change of the atomic density due to the dislocation, a local segregation or a charge at the dislocation core.

  8. AFM study of growth of Bi2Sr2-xLaxCuO6 thin films

    International Nuclear Information System (INIS)

    Haitao Yang; Hongjie Tao; Yingzi Zhang; Duogui Yang; Lin Li; Zhongxian Zhao

    1997-01-01

    c-axis-oriented Bi 2 Sr 1.6 La 0.4 CuO 6 thin films deposited on flat planes of (100)SrTiO 3 , (100)LaAlO 3 and (100)MgO substrates and vicinal planes (off-angle ∼ 6 deg.) of SrTiO 3 substrates by RF magnetron sputtering were studied by atomic force microscopy (AFM). T c of these films reached 29 K. Film thickness ranged from 15 nm to 600 nm. Two typical growth modes have been observed. AFM images of thin films on flat planes of substrates showed a terraced-island growth mode. By contrast, Bi-2201 thin films on vicinal planes of substrates showed a step-flow growth mode. The growth unit is a half-unit-cell in the c-axis for both growth modes. No example of spiral growth, which was thought to be the typical structure of YBCO thin films, was found in either of these kinds of thin films. (author)

  9. Growth and characterisation of potentiostatically electrodeposited Cu2O and Cu thin films

    International Nuclear Information System (INIS)

    Wijesundera, R.P.; Hidaka, M.; Koga, K.; Sakai, M.; Siripala, W.

    2006-01-01

    Cuprous oxide and copper thin films were potentiostatically electrodeposited in an acetate bath. Voltammetric curves were used to investigate the growth parameters; deposition potential, pH and temperature of the bath. Deposition potential dependency on the structural, morphological, optical and electronic properties of the films were investigated by the X-ray diffraction measurements, scanning electron micrographs, absorption measurements and dark and light current-voltage characterisations. It was observed that single phase polycrystalline Cu 2 O can be deposited from 0 to - 300 mV Vs saturated calomel electrode (SCE) and co-deposition of Cu and Cu 2 O starts at - 400 mV Vs SCE. Further increase in deposition potential from - 700 mV Vs SCE produces single phase Cu thin films. Single phase polycrystalline Cu 2 O thin films with cubic grains of 1-2 μm can be possible within the very narrow potential domain around - 200 mV Vs SCE. Enhanced photoresponse in a photoelectrochemical cell is produced by the Cu 2 O thin film prepared at - 400 mV Vs SCE, where Cu is co-deposited with Cu 2 O with random distribution of Cu spheres on the Cu 2 O surface. This study reveals that a single deposition bath can be used to deposit both Cu and Cu 2 O separately and an admixture of Cu-Cu 2 O by controlling the deposition parameters

  10. The growth and evolution of thin oxide films on delta-plutonium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Flores, Harry G [Los Alamos National Laboratory; Pugmire, David L [Los Alamos National Laboratory

    2009-01-01

    The common oxides of plutonium are the dioxide (PuO{sub 2}) and the sesquioxide (Pu{sub 2}O{sub 3}). The structure of an oxide on plutonium metal under air at room temperature is typically described as a thick PuO{sub 2} film at the gas-oxide interface with a thinner PuO{sub 2} film near the oxide-metal substrate interface. In a reducing environment, such as ultra high vacuum, the dioxide (Pu{sup 4+}; O/Pu = 2.0) readily converts to the sesquioxide (Pu{sup 3+}; O/Pu = 1.5) with time. In this work, the growth and evolution of thin plutonium oxide films is studied with x-ray photoelectron spectroscopy (XPS) under varying conditions. The results indicate that, like the dioxide, the sesquioxide is not stable on a very clean metal substrate under reducing conditions, resulting in substoichiometric films (Pu{sub 2}O{sub 3-y}). The Pu{sub 2}O{sub 3-y} films prepared exhibit a variety of stoichiometries (y = 0.2-1) as a function of preparation conditions, highlighting the fact that caution must be exercised when studying plutonium oxide surfaces under these conditions and interpreting resulting data.

  11. Thickness-controlled direct growth of nanographene and nanographite film on non-catalytic substrates

    Science.gov (United States)

    Du, Lei; Yang, Liu; Hu, Zhiting; Zhang, Jiazhen; Huang, Chunlai; Sun, Liaoxin; Wang, Lin; Wei, Dacheng; Chen, Gang; Lu, Wei

    2018-05-01

    Metal-catalyzed chemical vapor deposition (CVD) has been broadly employed for large-scale production of high-quality graphene. However, a following transfer process to targeted substrates is needed, which is incompatible with current silicon technology. We here report a new CVD approach to form nanographene and nanographite films with accurate thickness control directly on non-catalytic substrates such as silicon dioxide and quartz at 800 °C. The growth time is as short as a few seconds. The approach includes using 9-bis(diethylamino)silylanthracene as the carbon source and an atomic layer deposition (ALD) controlling system. The structure of the formed nanographene and nanographite films were characterized using atomic force microscopy, high resolution transmission electron microscopy, Raman scattering, and x-ray photoemission spectroscopy. The nanographite film exhibits a transmittance higher than 80% at 550 nm and a sheet electrical resistance of 2000 ohms per square at room temperature. A negative temperature-dependence of the resistance of the nanographite film is also observed. Moreover, the thickness of the films can be precisely controlled via the deposition cycles using an ALD system, which promotes great application potential for optoelectronic and thermoelectronic-devices.

  12. The effect of Na on Cu-K-In-Se thin film growth

    Science.gov (United States)

    Muzzillo, Christopher P.; Tong, Ho Ming; Anderson, Timothy J.

    2018-04-01

    Co-evaporation of Cu-KF-In-Se was performed on substrates with varied Na supply. Compositions of interest for photovoltaic absorbers were studied, with ratios of (K + Cu)/In ∼ 0.85 and K/(K + Cu) ∼ 0-0.57. Bare soda-lime glass (SLG) substrates had the highest Na supply as measured by secondary ion mass spectrometry, while SLG/Mo and SLG/SiO2/Mo substrates led to 3x and 3000x less Na in the growing film, respectively. Increased Na supply favored Cu1-xKxInSe2 (CKIS) alloy formation as proven by X-ray diffraction (XRD), while decreased Na supply favored the formation of CuInSe2 + KInSe2 mixed-phase films. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed the KInSe2 precipitates to be readily recognizable planar crystals. Extrinsic KF addition during film growth promoted diffusion of Na out from the various substrates and into the growing film, in agreement with previous reports. Time-resolved photoluminescence showed enhanced minority carrier lifetimes for films with moderate K compositions (0.04 interdependency can be used to engineer alkali metal bonding in Cu(In,Ga)(Se,S)2 absorbers to optimize both initial and long-term photovoltaic power generation.

  13. Growth of high quality AlN films on CVD diamond by RF reactive magnetron sputtering

    Science.gov (United States)

    Chen, Liang-xian; Liu, Hao; Liu, Sheng; Li, Cheng-ming; Wang, Yi-chao; An, Kang; Hua, Chen-yi; Liu, Jin-long; Wei, Jun-jun; Hei, Li-fu; Lv, Fan-xiu

    2018-02-01

    A highly oriented AlN layer has been successfully grown along the c-axis on a polycrystalline chemical vapor deposited (CVD) diamond by RF reactive magnetron sputtering. Structural, morphological and mechanical properties of the heterostructure were investigated by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Nano-indentation and Four-probe meter. A compact AlN film was demonstrated on the diamond layer, showing columnar grains and a low surface roughness of 1.4 nm. TEM results revealed a sharp AlN/diamond interface, which was characterized by the presence of a distinct 10 nm thick buffer layer resulting from the initial AlN growth stage. The FWHM of AlN (002) diffraction peak and its rocking curve are as low as 0.41° and 3.35° respectively, indicating a highly preferred orientation along the c-axis. AlN sputtered films deposited on glass substrates show a higher bulk resistivity (up to 3 × 1012 Ω cm), compared to AlN films deposited on diamond (∼1010 Ω cm). Finally, the film hardness and Young's modulus of AlN films on diamond are 25.8 GPa and 489.5 GPa, respectively.

  14. Effect of negative bias voltage on CrN films deposited by arc ion plating. I. Macroparticles filtration and film-growth characteristics

    International Nuclear Information System (INIS)

    Wang Qimin; Kim, Kwang Ho

    2008-01-01

    Chromium nitride (CrN) films were deposited on Si wafers by arc ion plating (AIP) at various negative bias voltages and several groups of N 2 /Ar gas flux ratios and chamber gas pressures. The authors systematically investigated the influence of negative bias voltage on the synthesis, composition, microstructure, and properties of the AIP CrN films. In this part (Part I), the investigations were mainly focused on the macroparticle distributions and film-growth characteristics. The results showed that macroparticle densities on the film surfaces decreased greatly by applying negative bias voltage, which can be affected by partial pressure of N 2 and Ar gases. From the statistical analysis of the experimental results, they proposed a new hybrid mechanism of ion bombardment and electrical repulsion. Also, the growth of the AIP CrN films was greatly altered by applying negative bias voltage. By increasing the bias voltage, the film surfaces became much smoother and the films evolved from apparent columnar microstructures to an equiaxed microstructure. The impinging high-energy Cr ions accelerated by negative bias voltages were deemed the inherent reason for the evolution of growth characteristics

  15. Growth, etching, and stability of sputtered ZnO:Al for thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Jorj Ian

    2011-07-01

    O:Al films can be increased up to 76 cm{sup 2}/Vs by annealing at high temperatures. Further, it is observed that this annealing process does not affect the morphology of the film and increases the total transmission in the solar cell relevant portion of the spectrum. Accelerated aging in a damp-heat is shown to affect the mobility primarily, and is thus likely related to poor transport across grain boundaries. Using deuterium as an isotopic marker, it is observed that the deuterium uptake was fairly linear with time and penetrated the whole film within 24 hours. Additionally, the deuterium is quickly replaced by hydrogen upon damp-heat treatment in water. It is concluded that the electrical degradation is related to the penetration of water via grain boundaries, and that the bulk of the reactions causing this degradation are fairly weak, such as the formation of zinc hydroxide. Additionally, the annealed high-mobility ZnO:Al films prove to be very stable in the damp-heat environment, exhibiting electron mobilities above 70 cm{sup 2}/Vs after 1000 hours of exposure. The initial points of attack during HCl etching of ZnO:Al, and the long-term etch evolution are shown to be related to certain grain boundaries built into the film during growth. The density of craters from an HCl etch is controllable by altering the temperature and concentration of the etching solution. It is further demonstrated that most acids exhibit etching behavior similar to that of HCl. Hydrofluoric acid (HF), however, exhibits unique etching characteristics with higher crater densities and sharper features. The crater density and shape are also shown to be controllable by etching in various concentrations of HF and in various mixtures of HF and HCl. Additional etching experiments are made to develop a polycrystalline ZnO:Al etching model. It is shown that basic and acidic solutions attack the same points on a polycrystalline ZnO:Al sample. The dependence of crater density on the acid concentration

  16. Grain growth: The key to understand solid-state dewetting of silver thin films

    International Nuclear Information System (INIS)

    Jacquet, P.; Podor, R.; Ravaux, J.; Teisseire, J.; Gozhyk, I.; Jupille, J.; Lazzari, R.

    2016-01-01

    The dynamics of solid-state dewetting of polycrystalline silver thin films in oxygen atmosphere was investigated with in situ and real-time environmental Scanning Electron Microscopy at high temperature combined with Atomic Force Microscopy. Three steps were identified during dewetting: induction, hole propagation without specific rim and sintering. Moreover, it was observed that a very selective grain growth, promoted by surface diffusion, plays a key role all along the process.

  17. Thin film growth behaviors on strained fcc(111) surface by kinetic Monte Carlo

    International Nuclear Information System (INIS)

    Doi, Y; Matsunaka, D; Shibutani, Y

    2009-01-01

    We study Ag islands grown on strained Ag(111) surfaces using kinetic Monte Carlo (KMC) simulations. We employed KMC parameters of activation energy and attempt frequency estimated by nudged elastic band (NEB) method and vibration analyses. We investigate influences of surface strain and substrate temperature on film growth. As the biaxial surface strain increases, the island density increases. As temperature increases, the shape of the island changes from dendric to hexagonal and the island density increases.

  18. Growth and hydrogenation of ultra-thin Mg films on Mo(111)

    DEFF Research Database (Denmark)

    Ostenfeld, Christopher Worsøe; Davies, Jonathan Conrad; Vegge, Tejs

    2005-01-01

    . Hydrogen cannot be adsorbed on magnesium films under UHV conditions. However, when evaporating Mg in a hydrogen background, a hydrogen overlayer is seen to adsorb at the Mg surface, due to the catalytic interaction with the Mo(1 1 1) substrate and subsequent spill-over. We show that two monolayers of Mg......The growth and hydrogenation of ultra-thin magnesium overlayers have been investigated on a Mo(1 1 1) single crystal substrate. For increasing magnesium coverages we observe intermediate stages in the TPD and LEISS profiles, which illustrate the transition from one monolayer to multilayer growth...

  19. Room temperature growth of biaxially aligned yttria-stabilized zirconia films on glass substrates by pulsed-laser deposition

    CERN Document Server

    Li Peng; Mazumder, J

    2003-01-01

    Room temperature deposition of biaxially textured yttria-stabilized zirconia (YSZ) films on amorphous glass substrates was successfully achieved by conventional pulsed-laser deposition. The influence of the surrounding gases, their pressure and the deposition time on the structure of the films was studied. A columnar growth process was revealed based on the experimental results. The grown biaxial texture appears as a kind of substrate independence, which makes it possible to fabricate in-plane aligned YSZ films on various substrates.

  20. Growth of large-size-two-dimensional crystalline pentacene grains for high performance organic thin film transistors

    Directory of Open Access Journals (Sweden)

    Chuan Du

    2012-06-01

    Full Text Available New approach is presented for growth of pentacene crystalline thin film with large grain size. Modification of dielectric surfaces using a monolayer of small molecule results in the formation of pentacene thin films with well ordered large crystalline domain structures. This suggests that pentacene molecules may have significantly large diffusion constant on the modified surface. An average hole mobility about 1.52 cm2/Vs of pentacene based organic thin film transistors (OTFTs is achieved with good reproducibility.

  1. Construction of Zn-incorporated multilayer films to promote osteoblasts growth and reduce bacterial adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Peng, E-mail: liupeng79@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Zhao, Yongchun; Yuan, Zhang [Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Ding, Hongyan [Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian, Jiangsu Province 223003 (China); Hu, Yan; Yang, Weihu [Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Cai, Kaiyong, E-mail: kaiyong_cai@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China)

    2017-06-01

    To improve the biological performance of titanium substrates, a bioactive multilayered structure of chitosan/gelatin pair, containing zinc ions, was constructed via a layer-by-layer self-assembly technique. The successful preparation of zinc ions incorporated multilayer films was demonstrated by scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements, respectively. The biological behaviors of osteoblasts adhered to modified Ti substrates were investigated in vitro via cytoskeleton observation, cell viability measurement, and alkaline phosphatase activity assay. The cytocompatibility evaluation verified that the present system was capable of promoting the growth of osteoblasts. In addition, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria were used to evaluate antibacterial property of modified Ti substrates. Bacterial adhesion and viability assay confirmed that Zn-loaded multilayer films were able to inhibit the adhesion and growth of bacteria. The approach presented here affords an alternative to reduce bacterial infection and promote osteoblast growth for titanium-based implants. - Highlights: • Polyelectrolyte multilayer films containing Zn ions were fabricated on Ti substrate. • Modified Ti substrate stimulated the biological responses of osteoblast. • Antibacterial property of Ti substrate was significantly improved. • The resulting material thus has potential application in orthopedic field.

  2. Growth and morphology of aluminium contacts on P3HT films

    Energy Technology Data Exchange (ETDEWEB)

    Kaune, Gunar [TU Muenchen, Physik-Department, Lehrstuhl fuer Funktionelle Materialien, James-Franck-Strasse 1, 85747 Garching (Germany); Martin-Luther-Universitaet Halle-Wittenberg, Institut fuer Physik, Fachgruppe Photovoltaik, Von-Danckelmann-Platz 3, 06120 Halle (Germany); Meier, Robert; Metwalli, Ezzeldin; Koerstgens, Volker; Mueller-Buschbaum, Peter [TU Muenchen, Physik-Department, Lehrstuhl fuer Funktionelle Materialien, James-Franck-Strasse 1, 85747 Garching (Germany); Schlage, Kai; Couet, Sebastien; Roth, Stephan V. [HASYLAB, DESY, Notkestrasse 85, 22603 Hamburg (Germany)

    2011-07-01

    The characteristics of organic electronic devices are strongly influenced by the type and structure of the metal electrodes needed to inject or extract charge carriers. Therefore understanding of the metal growth process and its relation to the interactions at the metal-organic interface are necessary. We investigate the growth of an aluminium layer on the surface of a P3HT thin film by in-situ application of grazing incidence small-angle X-ray scattering (GISAXS). By subsequent modelling of the scattering data the structural parameters of the growing film are extracted and a growth process is found, which proceeds two-dimensional by stacking single atomic layers on top each other. This process results in a homogeneous film with a large contact area to the polymer and is explained by a strong chemical interaction between aluminium and P3HT, which suppresses clustering of the metal on the polymer surface. The diffusion of single aluminium atoms into the P3HT and the formation of an intermixing layer is revealed by X-ray reflectivity measurements.

  3. Organic semiconductor growth and morphology considerations for organic thin-film transistors.

    Science.gov (United States)

    Virkar, Ajay A; Mannsfeld, Stefan; Bao, Zhenan; Stingelin, Natalie

    2010-09-08

    Analogous to conventional inorganic semiconductors, the performance of organic semiconductors is directly related to their molecular packing, crystallinity, growth mode, and purity. In order to achieve the best possible performance, it is critical to understand how organic semiconductors nucleate and grow. Clever use of surface and dielectric modification chemistry can allow one to control the growth and morphology, which greatly influence the electrical properties of the organic transistor. In this Review, the nucleation and growth of organic semiconductors on dielectric surfaces is addressed. The first part of the Review concentrates on small-molecule organic semiconductors. The role of deposition conditions on film formation is described. The modification of the dielectric interface using polymers or self-assembled mono-layers and their effect on organic-semiconductor growth and performance is also discussed. The goal of this Review is primarily to discuss the thin-film formation of organic semiconducting species. The patterning of single crystals is discussed, while their nucleation and growth has been described elsewhere (see the Review by Liu et. al).([¹]) The second part of the Review focuses on polymeric semiconductors. The dependence of physico-chemical properties, such as chain length (i.e., molecular weight) of the constituting macromolecule, and the influence of small molecular species on, e.g., melting temperature, as well as routes to induce order in such macromolecules, are described.

  4. Highly Oriented Growth of Piezoelectric Thin Films on Silicon Using Two-Dimensional Nanosheets as Growth Template Layer.

    Science.gov (United States)

    Nguyen, Minh D; Yuan, Huiyu; Houwman, Evert P; Dekkers, Matthijn; Koster, Gertjan; Ten Elshof, Johan E; Rijnders, Guus

    2016-11-16

    Ca 2 Nb 3 O 10 (CNOns) and Ti 0.87 O 2 (TiOns) metal oxide nanosheets (ns) are used as a buffer layer for epitaxial growth of piezoelectric capacitor stacks on Si and Pt/Ti/SiO 2 /Si (Pt/Si) substrates. Highly (001)- and (110)-oriented Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) films are achieved by utilizing CNOns and TiOns, respectively. The piezoelectric capacitors are characterized by polarization and piezoelectric hysteresis loops and by fatigue measurements. The devices fabricated with SrRuO 3 top and bottom electrodes directly on nanosheets/Si have ferroelectric and piezoelectric properties well comparable with devices that use more conventional oxide buffer layers (stacks) such as YSZ, CeO 2 /YSZ, or SrTiO 3 on Si. The devices grown on nanosheets/Pt/Si with Pt top electrodes show significantly improved polarization fatigue properties over those of similar devices grown directly on Pt/Si. The differences in properties are ascribed to differences in the crystalline structures and the density of the films. These results show a route toward the fabrication of single crystal piezoelectric thin films and devices with high quality, long-lifetime piezoelectric capacitor structures on nonperovskite and even noncrystalline substrates such as glass or polished metal surfaces.

  5. Growth and Characterisation of Pulsed-Laser Deposited Tin Thin Films on Cube-Textured Copper at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Szwachta G.

    2016-06-01

    Full Text Available High-quality titanium nitride thin films have been grown on a cube-textured copper surface via pulsed laser deposition. The growth of TiN thin films has been very sensitive to pre-treatment procedure and substrate temperature. It is difficult to grow heteroexpitaxial TiN films directly on copper tape due to large differences in lattice constants, thermal expansion coefficients of the two materials as well as polycrystalline structure of substrate. The X-Ray diffraction measurement revealed presence of high peaks belonged to TiN(200 and TiN(111 thin films, depending on used etcher of copper surface. The electron diffraction patterns of TiN(200/Cu films confirmed the single-crystal nature of the films with cube-on-cube epitaxy. The high-resolution microscopy on our films revealed sharp interfaces between copper and titanium nitride with no presence of interfacial reaction.

  6. Growth and thermal oxidation of Ru and ZrO2 thin films as oxidation protective layers

    NARCIS (Netherlands)

    Coloma Ribera, R.

    2017-01-01

    This thesis focuses on the study of physical and chemical processes occurring during growth and thermal oxidation of Ru and ZrO2 thin films. Acting as oxidation resistant capping materials to prevent oxidation of layers underneath, these films have several applications, i.e., in microelectronics

  7. Decoding Nucleation and Growth of Zeolitic Imidazolate Framework Thin Films with Atomic Force Microscopy and Vibrational Spectroscopy

    NARCIS (Netherlands)

    Ozturk, Zafer; Filez, Matthias; Weckhuysen, Bert M.

    2017-01-01

    The synthesis of metal-organic framework (MOF) thin films has garnered significant attention during the past decade. By better understanding the parameters governing the nucleation and growth of such thin films, their properties can be rationally tuned, empowering their application as (reactive)

  8. Morphology and grain structure evolution during epitaxial growth of Ag films on native-oxide-covered Si surface

    International Nuclear Information System (INIS)

    Hur, Tae-Bong; Kim, Hong Koo; Perello, David; Yun, Minhee; Kulovits, Andreas; Wiezorek, Joerg

    2008-01-01

    Epitaxial nanocrystalline Ag films were grown on initially native-oxide-covered Si(001) substrates using radio-frequency magnetron sputtering. Mechanisms of grain growth and morphology evolution were investigated. An epitaxially oriented Ag layer (∼5 nm thick) formed on the oxide-desorbed Si surface during the initial growth phase. After a period of growth instability, characterized as kinetic roughening, grain growth stagnation, and increase of step-edge density, a layer of nanocrystalline Ag grains with a uniform size distribution appeared on the quasi-two-dimensional layer. This hierarchical process of film formation is attributed to the dynamic interplay between incoming energetic Ag particles and native oxide. The cyclic interaction (desorption and migration) of the oxide with the growing Ag film is found to play a crucial role in the characteristic evolution of grain growth and morphology change involving an interval of grain growth stagnation

  9. Modeling growth kinetics of thin films made by atomic layer deposition in lateral high-aspect-ratio structures

    Science.gov (United States)

    Ylilammi, Markku; Ylivaara, Oili M. E.; Puurunen, Riikka L.

    2018-05-01

    The conformality of thin films grown by atomic layer deposition (ALD) is studied using all-silicon test structures with long narrow lateral channels. A diffusion model, developed in this work, is used for studying the propagation of ALD growth in narrow channels. The diffusion model takes into account the gas transportation at low pressures, the dynamic Langmuir adsorption model for the film growth and the effect of channel narrowing due to film growth. The film growth is calculated by solving the diffusion equation with surface reactions. An efficient analytic approximate solution of the diffusion equation is developed for fitting the model to the measured thickness profile. The fitting gives the equilibrium constant of adsorption and the sticking coefficient. This model and Gordon's plug flow model are compared. The simulations predict the experimental measurement results quite well for Al2O3 and TiO2 ALD processes.

  10. Metal thin film growth on multimetallic surfaces: From quaternary metallic glass to binary crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Dapeng [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    The work presented in this thesis mainly focuses on the nucleation and growth of metal thin films on multimetallic surfaces. First, we have investigated the Ag film growth on a bulk metallic glass surface. Next, we have examined the coarsening and decay of bilayer Ag islands on NiAl(110) surface. Third, we have investigated the Ag film growth on NiAl(110) surface using low-energy electron diffraction (LEED). At last, we have reported our investigation on the epitaxial growth of Ni on NiAl(110) surface. Some general conclusions can be drawn as follows. First, Ag, a bulk-crystalline material, initially forms a disordered wetting layer up to 4-5 monolayers on Zr-Ni-Cu-Al metallic glass. Above this coverage, crystalline 3D clusters grow, in parallel with the flatter regions. The cluster density increases with decreasing temperature, indicating that the conditions of island nucleation are far-from-equilibrium. Within a simple model where clusters nucleate whenever two mobile Ag adatoms meet, the temperature-dependence of cluster density yields a (reasonable) upper limit for the value of the Ag diffusion barrier on top of the Ag wetting layer of 0.32 eV. Overall, this prototypical study suggests that it is possible to grow films of a bulk-crystalline metal that adopt the amorphous character of a glassy metal substrate, if film thickness is sufficiently low. Next, the first study of coarsening and decay of bilayer islands has been presented. The system was Ag on NiAl(110) in the temperature range from 185 K to 250 K. The coarsening behavior, has some similarities to that seen in the Ag(110) homoepitaxial system studied by Morgenstern and co-workers. At 185 K and 205 K, coarsening of Ag islands follows a Smoluchowski ripening pathway. At 205 K and 250 K, the terrace diffusion limited Ostwald ripening dominants. The experimental observed temperature for the transition from SR to OR is 205 K. The SR exhibits anisotropic island diffusion and the OR exhibits 1D decay of island

  11. Growth and magnetic properties dependence of the Co–Cu/Cu films electrodeposited under high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Franczak, Agnieszka, E-mail: agnieszka.franczak@mtm.kuleuven.be [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); Department of Materials Science (MTM), KU Leuven, Kasteelpark Arenberg 44, 3001 Haverlee (Leuven) (Belgium); Levesque, Alexandra [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); Zabinski, Piotr [Laboratory of Physical Chemistry and Electrochemistry, Faculty of Non-Ferrous Metals, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Li, Donggang [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, 314 Box, 110004 Shenyang (China); Czapkiewicz, Maciej [Department of Electronics, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Kowalik, Remigiusz [Laboratory of Physical Chemistry and Electrochemistry, Faculty of Non-Ferrous Metals, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Bohr, Frédéric [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); and others

    2015-07-15

    The present work is focused on the investigations of magnetic properties dependence on microstructure of Co–Cu/Cu films electrodeposited under superimposed high magnetic field. The experimental results indicate a strong effect of an external magnetic field on the morphology of deposited films, more precisely on the Co:Cu ratio that determines the film growth. It is shown that the Co–Cu/Cu films electrodeposited without superimposed magnetic field consisted of two clearly visible features: compact film with incorporated granular particles. Under a superimposed external high magnetic field the privilege growth of the particles was induced. As a consequence, development of the well-defined branched structure of Co–Cu/Cu film was observed. In contrary, the phase compositional investigations do not reveal any changes in the phase formation during electrodeposition under magnetic field conditions. Thus, it is assumed that a strong growth of Co–Cu/Cu films in (111) direction under magnetic or non-magnetic electrodeposition conditions is related with the growth of Cu (111) plane and embedded into it some of the Co fcc atoms of same (111) orientation, as well as the Co hcp atoms that grows in the (002) direction. This non-equilibrium growth of Co–Cu/Cu films under magnetic deposition conditions affects strongly the magnetic properties of deposited films, revealing that films obtained under magnetic fields higher than 3 T were no more magnetic materials. - Highlights: • Co–Cu/Cu electrodeposits were obtained at elevated temperature under HMFs. • The effects of HMFs on microstructure and magnetic properties were investigated. • Interesting morphological changes due to HMFs has been observed. • Changes in Co:Cu ratio due to HMFs modified the magnetic properties of deposits.

  12. Growth and magnetic properties dependence of the Co–Cu/Cu films electrodeposited under high magnetic fields

    International Nuclear Information System (INIS)

    Franczak, Agnieszka; Levesque, Alexandra; Zabinski, Piotr; Li, Donggang; Czapkiewicz, Maciej; Kowalik, Remigiusz; Bohr, Frédéric

    2015-01-01

    The present work is focused on the investigations of magnetic properties dependence on microstructure of Co–Cu/Cu films electrodeposited under superimposed high magnetic field. The experimental results indicate a strong effect of an external magnetic field on the morphology of deposited films, more precisely on the Co:Cu ratio that determines the film growth. It is shown that the Co–Cu/Cu films electrodeposited without superimposed magnetic field consisted of two clearly visible features: compact film with incorporated granular particles. Under a superimposed external high magnetic field the privilege growth of the particles was induced. As a consequence, development of the well-defined branched structure of Co–Cu/Cu film was observed. In contrary, the phase compositional investigations do not reveal any changes in the phase formation during electrodeposition under magnetic field conditions. Thus, it is assumed that a strong growth of Co–Cu/Cu films in (111) direction under magnetic or non-magnetic electrodeposition conditions is related with the growth of Cu (111) plane and embedded into it some of the Co fcc atoms of same (111) orientation, as well as the Co hcp atoms that grows in the (002) direction. This non-equilibrium growth of Co–Cu/Cu films under magnetic deposition conditions affects strongly the magnetic properties of deposited films, revealing that films obtained under magnetic fields higher than 3 T were no more magnetic materials. - Highlights: • Co–Cu/Cu electrodeposits were obtained at elevated temperature under HMFs. • The effects of HMFs on microstructure and magnetic properties were investigated. • Interesting morphological changes due to HMFs has been observed. • Changes in Co:Cu ratio due to HMFs modified the magnetic properties of deposits

  13. Total-dose radiation-induced degradation of thin film ferroelectric capacitors

    International Nuclear Information System (INIS)

    Schwank, J.R.; Nasby, R.D.; Miller, S.L.; Rodgers, M.S.; Dressendorfer, P.V.

    1990-01-01

    Thin film PbZr y Ti 1-y O 3 (PZT) ferroelectric memories offer the potential for radiation-hardened, high-speed nonvolatile memories with good retention and fatigue properties. In this paper we explore in detail the radiation hardness of PZT ferroelectric capacitors. Ferroelectric capacitors were irradiated using x-ray and Co-60 sources to dose levels up to 16 Mrad(Si). The capacitors were characterized for their memory properties both before and after irradiation. The radiation hardness was process dependent. Three out of four processes resulted in capacitors that showed less than 30% radiation-induced degradation in retained polarization charge and remanent polarization after irradiating to 16 Mrad(Si). On the other hand, one of the processes showed significant radiation-induced degradation in retained polarization charge and remanent polarization at dose levels above 1 Mrad(Si). The decrease in retained polarization charge appears to be due to an alteration of the switching characteristics of the ferroelectric due to changes in the internal fields. The radiation-induced degradation is recoverable by a postirradiation biased anneal and can be prevented entirely if devices are cycled during irradiation. The authors have developed a model to simulate the observed degradation

  14. Model experiments on growth modes and interface electronics of CuInS{sub 2}: Ultrathin epitaxial films on GaAs(100) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Calvet, Wolfram [Institute for Heterogeneous Materials Systems, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109, Berlin (Germany); Lewerenz, Hans-Joachim [Joint Center for Artificial Photosynthesis, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91101 (United States); Pettenkofer, Christian [Institute Silicon Photovoltaics, Helmholtz-Zentrum Berlin, Kekulestrasse 5, 12489, Berlin (Germany)

    2014-09-15

    The heterojunction formation between GaAs(100) and CuInS{sub 2} is investigated using ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). Thin layers of CuInS{sub 2} films were deposited in a step-by-step process on wet chemically pre-treated GaAs(100) surfaces by molecular beam epitaxy (MBE) with a total upper thickness limit of the films of 60 nm. The film growth starts from a sulfur-rich GaAs(100) surface. XPS core level analysis of the substrate and film reveals initially a transitory growth regime with the formation of a Ga containing chalcopyrite phase. With increasing film thickness, a change in stoichiometry from Cu-poor to Cu-rich composition is observed. The evaluation of the LEED data shows the occurrence of a recrystallization process where the film orientation follows that of the substrate with the epitaxial relation GaAs{100} parallel CuInS{sub 2}{001}. On the completed junction with a CuInS{sub 2} film thickness of 60 nm, the band discontinuities of the GaAs(100)/CuInS{sub 2} structure measured with XPS and UPS were determined as ΔE{sub V} = 0.1 ± 0.1 eV and ΔE{sub C} = 0.0 ± 0.1 eV, thus showing a type II band alignment. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. One unit-cell seed layer induced epitaxial growth of heavily nitrogen doped anatase TiO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, T L; Hirose, Y; Hitosugi, T; Hasegawa, T [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan)], E-mail: chen@ksp.or.jp

    2008-03-21

    We present a novel way to obtain heavily nitrogen doped anatase TiO{sub 2} films by using a solid-state nitrogen source. Epitaxial growth of the films was realized by introducing one unit-cell seed layer, which was indicated by reflection high-energy electron diffraction as intensity oscillation. Results of x-ray diffraction and x-ray photoelectron spectroscopy confirmed that the films were in the anatase phase heavily doped with nitrogen of {approx}15 at%. The films obtained exhibited considerable narrowing of the optical bandgap, resulting in an enhancement of absorption in the visible-light region. (fast track communication)

  16. Practice-oriented optical thin film growth simulation via multiple scale approach

    Energy Technology Data Exchange (ETDEWEB)

    Turowski, Marcus, E-mail: m.turowski@lzh.de [Laser Zentrum Hannover e.V., Hollerithallee 8, Hannover 30419 (Germany); Jupé, Marco [Laser Zentrum Hannover e.V., Hollerithallee 8, Hannover 30419 (Germany); QUEST: Centre of Quantum Engineering and Space-Time Research, Leibniz Universität Hannover (Germany); Melzig, Thomas [Fraunhofer Institute for Surface Engineering and Thin Films IST, Bienroder Weg 54e, Braunschweig 30108 (Germany); Moskovkin, Pavel [Research Centre for Physics of Matter and Radiation (PMR-LARN), University of Namur (FUNDP), 61 rue de Bruxelles, Namur 5000 (Belgium); Daniel, Alain [Centre for Research in Metallurgy, CRM, 21 Avenue du bois Saint Jean, Liège 4000 (Belgium); Pflug, Andreas [Fraunhofer Institute for Surface Engineering and Thin Films IST, Bienroder Weg 54e, Braunschweig 30108 (Germany); Lucas, Stéphane [Research Centre for Physics of Matter and Radiation (PMR-LARN), University of Namur (FUNDP), 61 rue de Bruxelles, Namur 5000 (Belgium); Ristau, Detlev [Laser Zentrum Hannover e.V., Hollerithallee 8, Hannover 30419 (Germany); QUEST: Centre of Quantum Engineering and Space-Time Research, Leibniz Universität Hannover (Germany)

    2015-10-01

    Simulation of the coating process is a very promising approach for the understanding of thin film formation. Nevertheless, this complex matter cannot be covered by a single simulation technique. To consider all mechanisms and processes influencing the optical properties of the growing thin films, various common theoretical methods have been combined to a multi-scale model approach. The simulation techniques have been selected in order to describe all processes in the coating chamber, especially the various mechanisms of thin film growth, and to enable the analysis of the resulting structural as well as optical and electronic layer properties. All methods are merged with adapted communication interfaces to achieve optimum compatibility of the different approaches and to generate physically meaningful results. The present contribution offers an approach for the full simulation of an Ion Beam Sputtering (IBS) coating process combining direct simulation Monte Carlo, classical molecular dynamics, kinetic Monte Carlo, and density functional theory. The simulation is performed exemplary for an existing IBS-coating plant to achieve a validation of the developed multi-scale approach. Finally, the modeled results are compared to experimental data. - Highlights: • A model approach for simulating an Ion Beam Sputtering (IBS) process is presented. • In order to combine the different techniques, optimized interfaces are developed. • The transport of atomic species in the coating chamber is calculated. • We modeled structural and optical film properties based on simulated IBS parameter. • The modeled and the experimental refractive index data fit very well.

  17. Non-vacuum growth of graphene films using solid carbon source

    International Nuclear Information System (INIS)

    Nguyen, Ba-Son; Lin, Jen-Fin; Perng, Dung-Ching

    2015-01-01

    This study demonstrates that air annealing can grow high-quality graphene films on the surface of polycrystalline nickel film with the help of an effective SiO 2 capping layer. The number of graphene layers can be modulated by the amount of carbon embedded in the Ni film before annealing. Raman analysis results, transmission electron microscopy images, and electron diffraction patterns of the samples confirm that graphene films can be grown in air with an oxygen blocking layer and a 10 °C/s cooling rate in an open-vented rapid thermal annealing chamber or an open tube furnace. The high-quality low-defect air-annealing grown graphene is comparable to commercially available graphene grown via chemical vapor deposition. The proposed graphene growth using air annealing technique is simple and low-cost, making it highly attractive for mass production. It is transfer-free to a silicon substrate and can speed up graphene development, opening up new applications

  18. Time-dependent changes in the growth of ultrathin ionic liquid films on Ag(111).

    Science.gov (United States)

    Lexow, Matthias; Talwar, Timo; Heller, Bettina S J; May, Benjamin; Bhuin, Radha G; Maier, Florian; Steinrück, Hans-Peter

    2018-05-09

    Various amounts of the ionic liquids (ILs) [C1C1Im][Tf2N] and [C8C1Im][Tf2N] were deposited in vacuo by physical vapour deposition (PVD) on single crystalline Ag(111) at room temperature and subsequently monitored by angle-resolved X-ray photoelectron spectroscopy (ARXPS) as a function of time. For very low coverages of up to one closed molecular layer, an initial wetting layer was rapidly formed for both ILs. Deposition of higher amounts of [C1C1Im][Tf2N] revealed an initial three-dimensional film morphology. On the time scale of hours, characteristic changes of the XPS signals were observed. These are interpreted as island spreading and a transformation towards a nearly two dimensional [C1C1Im][Tf2N] film as the final state. In contrast, a film morphology close to 2D was found from the very beginning for [C8C1Im][Tf2N] deposited on Ag(111) demonstrating the influence of the alkyl chain length on the growth kinetics. These studies also highlight the suitability of time-resolved ARXPS for the investigation of IL/solid interfaces, which play a crucial role in IL thin film applications such as in catalysis, sensor, lubrication, and coating technologies.

  19. Direct growth of nanocrystalline hexagonal boron nitride films on dielectric substrates

    Energy Technology Data Exchange (ETDEWEB)

    Tay, Roland Yingjie [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Temasek Laboratories@NTU, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Tsang, Siu Hon [Temasek Laboratories@NTU, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Loeblein, Manuela; Chow, Wai Leong [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); CNRS-International NTU Thales Research Alliance CINTRA UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Singapore, Singapore 637553 (Singapore); Loh, Guan Chee [Institue of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore); Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States); Toh, Joo Wah; Ang, Soon Loong [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Teo, Edwin Hang Tong, E-mail: htteo@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore)

    2015-03-09

    Atomically thin hexagonal-boron nitride (h-BN) films are primarily synthesized through chemical vapor deposition (CVD) on various catalytic transition metal substrates. In this work, a single-step metal-catalyst-free approach to obtain few- to multi-layer nanocrystalline h-BN (NCBN) directly on amorphous SiO{sub 2}/Si and quartz substrates is demonstrated. The as-grown thin films are continuous and smooth with no observable pinholes or wrinkles across the entire deposited substrate as inspected using optical and atomic force microscopy. The starting layers of NCBN orient itself parallel to the substrate, initiating the growth of the textured thin film. Formation of NCBN is due to the random and uncontrolled nucleation of h-BN on the dielectric substrate surface with no epitaxial relation, unlike on metal surfaces. The crystallite size is ∼25 nm as determined by Raman spectroscopy. Transmission electron microscopy shows that the NCBN formed sheets of multi-stacked layers with controllable thickness from ∼2 to 25 nm. The absence of transfer process in this technique avoids any additional degradation, such as wrinkles, tears or folding and residues on the film which are detrimental to device performance. This work provides a wider perspective of CVD-grown h-BN and presents a viable route towards large-scale manufacturing of h-BN substrates and for coating applications.

  20. Non-vacuum growth of graphene films using solid carbon source

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba-Son [Department of Mechanical Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Faculty of Mechatronics – Electronics, Lac Hong University, 10 Huynh Van Nghe Road, Bienhoa (Viet Nam); Lin, Jen-Fin, E-mail: jflin@mail.ncku.edu.tw, E-mail: dcperng@ee.ncku.edu.tw [Department of Mechanical Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Perng, Dung-Ching, E-mail: jflin@mail.ncku.edu.tw, E-mail: dcperng@ee.ncku.edu.tw [Center for Micro/Nano Science and Technology, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Institute of Microelectronics and Electrical Engineering Department, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China)

    2015-06-01

    This study demonstrates that air annealing can grow high-quality graphene films on the surface of polycrystalline nickel film with the help of an effective SiO{sub 2} capping layer. The number of graphene layers can be modulated by the amount of carbon embedded in the Ni film before annealing. Raman analysis results, transmission electron microscopy images, and electron diffraction patterns of the samples confirm that graphene films can be grown in air with an oxygen blocking layer and a 10 °C/s cooling rate in an open-vented rapid thermal annealing chamber or an open tube furnace. The high-quality low-defect air-annealing grown graphene is comparable to commercially available graphene grown via chemical vapor deposition. The proposed graphene growth using air annealing technique is simple and low-cost, making it highly attractive for mass production. It is transfer-free to a silicon substrate and can speed up graphene development, opening up new applications.

  1. Thin film growth of CaFe2As2 by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Hatano, T; Fujimoto, R; Nakamura, I; Mori, Y; Ikuta, H; Kawaguchi, T; Harada, S; Ujihara, T

    2016-01-01

    Film growth of CaFe 2 As 2 was realized by molecular beam epitaxy on six different substrates that have a wide variation in the lattice mismatch to the target compound. By carefully adjusting the Ca-to-Fe flux ratio, we obtained single-phase thin films for most of the substrates. Interestingly, an expansion of the CaFe 2 As 2 lattice to the out-of-plane direction was observed for all films, even when an opposite strain was expected. A detailed microstructure observation of the thin film grown on MgO by transmission electron microscope revealed that it consists of cube-on-cube and 45°-rotated domains. The latter domains were compressively strained in plane, which caused a stretching along the c-axis direction. Because the domains were well connected across the boundary with no appreciable discontinuity, we think that the out-of-plane expansion in the 45°-rotated domains exerted a tensile stress on the other domains, resulting in the unexpectedly large c-axis lattice parameter, despite the apparently opposite lattice mismatch. (paper)

  2. Thin film growth of CaFe2As2 by molecular beam epitaxy

    Science.gov (United States)

    Hatano, T.; Kawaguchi, T.; Fujimoto, R.; Nakamura, I.; Mori, Y.; Harada, S.; Ujihara, T.; Ikuta, H.

    2016-01-01

    Film growth of CaFe2As2 was realized by molecular beam epitaxy on six different substrates that have a wide variation in the lattice mismatch to the target compound. By carefully adjusting the Ca-to-Fe flux ratio, we obtained single-phase thin films for most of the substrates. Interestingly, an expansion of the CaFe2As2 lattice to the out-of-plane direction was observed for all films, even when an opposite strain was expected. A detailed microstructure observation of the thin film grown on MgO by transmission electron microscope revealed that it consists of cube-on-cube and 45°-rotated domains. The latter domains were compressively strained in plane, which caused a stretching along the c-axis direction. Because the domains were well connected across the boundary with no appreciable discontinuity, we think that the out-of-plane expansion in the 45°-rotated domains exerted a tensile stress on the other domains, resulting in the unexpectedly large c-axis lattice parameter, despite the apparently opposite lattice mismatch.

  3. On the nucleation and initial film growth of rod-like organic molecules

    Science.gov (United States)

    Winkler, Adolf

    2016-10-01

    In this article, some fundamental topics related to the initial steps of organic film growth are reviewed. General conclusions will be drawn based on experimental results obtained for the film formation of oligophenylene and pentacene molecules on gold and mica substrates. Thin films were prepared via physical vapor deposition under ultrahigh-vacuum conditions and characterized in-situ mainly by thermal desorption spectroscopy, and ex-situ by X-ray diffraction and atomic force microscopy. In this short review article the following topics will be discussed: What are the necessary conditions to form island-like films which are either composed of flat-lying or of standing molecules? Does a wetting layer exist below and in between the islands? What is the reason behind the occasionally observed bimodal island size distribution? Can one describe the nucleation process with the diffusion-limited aggregation model? Do the impinging molecules directly adsorb on the surface or rather via a hot-precursor state? Finally, it will be described how the critical island size can be determined by an independent measurement of the deposition rate dependence of the island density and the capture-zone distribution via a universal relationship.

  4. A review of the growth of V2O5 films from 1885 to 2010

    International Nuclear Information System (INIS)

    Beke, Szabolcs

    2011-01-01

    This year is the 125th anniversary of the first synthesis of V 2 O 5 gels. The fascinating properties and wide application range of V 2 O 5 thin films have attracted significant attention over the past decades. Its wide optical band gap, layered structure, good chemical and thermal stability and excellent thermoelectric and electrochromic properties have made V 2 O 5 a promising material for industrial applications such as gas sensors, electrochromic devices, optical switching devices, and reversible cathode materials for Li batteries. Gels were the first form in which V 2 O 5 was synthesized at the end of the 19th century. Interest started to grow in the 1980s due to the discovery of their semiconducting properties and their use in antistatic coatings in the photographic industry. The rapid development of the sol-gel process brought new interest in V 2 O 5 gels. Following a short discussion of vanadium oxides and V 2 O 5 , I summarize all thin film preparation techniques known up to now and use reported optical band gaps to characterize different growth methods. An estimation of the Bohr radius for V 2 O 5 is also presented. This article provides an up-to-date review of more than a century (1885-2010) of research on the growth of vanadium oxide thin films. Nonetheless, due to the huge number of publications in the field, only those are selected and described which, according to the author, contribute the most to the field's further development.

  5. Surfactant-mediated growth of ultrathin Ge and Si films and their interfaces: Interference-enhanced Raman study

    OpenAIRE

    Kanakaraju, S; Sood, AK; Mohan, S

    2000-01-01

    We report on the growth and interfaces of ultrathin polycrystalline Ge and Si films when they are grown on each other using ion beam sputter deposition with and without surfactant at different growth temperatures, studied using interference enhanced Raman spectroscopy. Ge films grown on Si without surfactant show Ge segregation at the interfaces forming an alloy of GexSi1-x as indicated by the Ge-Si Raman mode. However, use of Sb as surfactant strongly suppresses the intermixing. Also Si film...

  6. Wafer bowing control of free-standing heteroepitaxial diamond (100) films grown on Ir(100) substrates via patterned nucleation growth

    International Nuclear Information System (INIS)

    Yoshikawa, Taro; Kodama, Hideyuki; Kono, Shozo; Suzuki, Kazuhiro; Sawabe, Atsuhito

    2015-01-01

    The potential of patterned nucleation growth (PNG) technique to control the wafer bowing of free-standing heteroepitaxial diamond films was investigated. The heteroepitaxial diamond (100) films were grown on an Ir(100) substrate via PNG technique with different patterns of nucleation regions (NRs), which were dot-arrays with 8 or 13 μm pitch aligned to < 100 > or < 110 > direction of the Ir(100) substrate. The wafer bows and the local stress distributions of the free-standing films were measured using a confocal micro-Raman spectrometer. For each NR pattern, the stress evolutions within the early stage of diamond growth were also studied together with a scanning electron microscopic observation of the coalescing diamond particles. These investigations revealed that the NR pattern, in terms of pitch and direction of dot-array, strongly affects the compressive stress on the nucleation side of the diamond film and dominantly contributes to the elastic deformation of the free-standing film. This indicates that the PNG technique with an appropriate NR pattern is a promising solution to fabricate free-standing heteroepitaxial diamond films with extremely small bows. - Highlights: • Wafer bowing control of free-standing heteroepitaxial diamond (100) films • Effect of patterned nucleation and growth (PNG) technique on wafer bowing reduction • Influence of nucleation region patterns of PNG on wafer bowing • Internal stress analysis of PNG films via confocal micro-Raman spectroscopy

  7. In situ growth rate measurements during plasma-enhanced chemical vapour deposition of vertically aligned multiwall carbon nanotube films

    International Nuclear Information System (INIS)

    Joensson, M; Nerushev, O A; Campbell, E E B

    2007-01-01

    In situ laser reflectivity measurements are used to monitor the growth of multiwalled carbon nanotube (MWCNT) films grown by DC plasma-enhanced chemical vapour deposition (PECVD) from an iron catalyst film deposited on a silicon wafer. In contrast to thermal CVD growth, there is no initial increase in the growth rate; instead, the initial growth rate is high (as much as 10 μm min -1 ) and then drops off rapidly to reach a steady level (2 μm min -1 ) for times beyond 1 min. We show that a limiting factor for growing thick films of multiwalled nanotubes (MWNTs) using PECVD can be the formation of an amorphous carbon layer at the top of the growing nanotubes. In situ reflectivity measurements provide a convenient technique for detecting the onset of the growth of this layer

  8. Fetal and infant growth patterns associated with total and abdominal fat distribution in school-age children

    NARCIS (Netherlands)

    Gishti, O.; Gaillard, R.; Manniesing, R.; Abrahamse-Berkeveld, M.; Beek, E.M. van der; Heppe, D.H.M.; Steegers, E.A.P.; Hofman, A.; Duijts, L.; Durmus, B.u.; Jaddoe, V.W.

    2014-01-01

    Context: Higher infant growth rates are associated with an increased risk of obesity in later life. Objective: We examined the associations of longitudinally measured fetal and infant growth patterns with total and abdominal fat distribution in childhood. Design, Settings and participants:We

  9. Growth and magnetic structure of La0.67Sr0.33MnO3 films

    International Nuclear Information System (INIS)

    Brown, G.W.; Jia, Q.X.; Peterson, E.J.; Hristova, D.K.; Hundley, M.F.; Thompson, J.D.; Maggiore, C.J.; Tesmer, J.; Hawley, M.E.

    1997-01-01

    Growth of LaMnO 3 films that exhibit colossal magnetoresistance (CMR) has concentrated heavily on Ca doped materials. However, since the 33% Sr doped films are ferromagnetic at room temperature, they are ideal candidates for dual growth-magnetic structure studies using scanned probe techniques. In this study, interest was focused on the relations between growth/processing parameters, film morphology, and electronic/magnetic properties. In addition, films were grown on both LaAlO 3 (LAO) and SrTiO 3 (STO) to examine the results of stress induced by different substrate mismatches. La 0.67 Sr 0.33 MnO 3 (LSMO) was grown using pulsed laser deposition (PLD) at temperatures between 500 C and 800 C. The film microstructure, crystallinity, and magnetic and electrical properties were characterized by room temperature scanning tunneling microscopy (STM), atomic force microscopy (AFM), magnetic force microscopy (MFM), x-ray diffraction, and temperature dependent transport and magnetization measurements. The growth trends follow those previously reported for Ca doped films. Grains increase in size with increasing temperature and coalesce into extended layers after annealing. Although topographic contributions complicate interpretation of some MFM data, local magnetic structure observed here is generally associated with film defects

  10. Stoichiometry-, phase- and orientation-controlled growth of polycrystalline pyrite (FeS 2) thin films by MOCVD

    Science.gov (United States)

    Höpfner, C.; Ellmer, K.; Ennaoui, A.; Pettenkofer, C.; Fiechter, S.; Tributsch, H.

    1995-06-01

    The growth process of polycrystalline pyrite thin films employing low pressure metalorganic chemical vapor deposition (LP-MOCVD) in a vertical cold wall reactor has been investigated. Iron pentacarbonyl (IPC) and t-butyldisulfide (TBDS) were utilized as precursors. Study of the growth rate as a function of temperature reveals a kinetically controlled growth process with an activation energy of 73 kJ / mol over the temperature range from 250 to 400°C. From 500 to 630°C, the growth rate is mainly mass transport limited. Decomposition of the films into pyrrhotite (Fe 1 - xS) occurs at higher growth temperatures. The {S}/{Fe} ratio in the films has been controlled from 1.23 up to 2.03 by changing the TBDS partial pressure. With increasing deposition temperature, the crystallites in the films show the tendency to grow [100]-oriented on amorphous substrates at a growth rate of 2.5 Å / s. The grains show a preferential orientation in the [111] direction upon lowering the growth rate down to 0.3 Å / s. Temperatures above 550°C are beneficial in enhancing the grain size in the columnar structured films up to 1.0 μm.

  11. Stoichiometry-, phase- and orientation-controlled growth of polycrystalline pyrite (FeS{sub 2}) thin films by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Hoepfner, C.; Ellmer, K.; Ennaoui, A.; Pettenkofer, C.; Fiechter, S.; Tributsch, H. [Hahn-Meitner-Institut Berlin, Abteilung Solare Energetik, Berlin (Germany)

    1995-06-01

    The growth process of polycrystalline pyrite thin films employing low pressure metalorganic chemical vapor deposition (LP-MOCVD) in a vertical cold wall reactor has been investigated. Iron pentacarbonyl (IPC) and t-butyldisulfide (TBDS) were utilized as precursors. Study of the growth rate as a function of temperature reveals a kinetically controlled growth process with an activation energy of 73 kJ/mol over the temperature range from 250 to 400C. From 500 to 630C, the growth rate is mainly mass transport limited. Decomposition of the films into pyrrhotite (Fe{sub 1-x}S) occurs at higher growth temperatures. The S/Fe ratio in the films has been controlled from 1.23 up to 2.03 by changing the TBDS partial pressure. With increasing deposition temperature, the crystallites in the films show the tendency to grow [100]-oriented on amorphous substrates at a growth rate of 2.5 A/s. The grains show a preferential orientation in the [111] direction upon lowering the growth rate down to 0.3 A/s. Temperatures above 550C are beneficial in enhancing the grain size in the columnar structured films up to 1.0 {mu}m

  12. MOCVD Growth and Characterization of n-type Zinc Oxide Thin Films

    Science.gov (United States)

    Ben-Yaacov, Tammy

    In the past decade, there has been widespread effort in the development of zinc oxide as a II-V1 semiconductor material. ZnO has potential advantages in optoelectronip device applications due to its unique electrical and optical properties. What stands out among these properties is its wide direct bandgap of 3.37 eV and its high electrical conductivity and transparency in the visible and near-UV regions of the spectrum. ZnO can be grown heteroepitaxially on GaN under near lattice-matched conditions and homoepitaxially as well, as high-quality bulk ZnO substrates are commercially available. This dissertation focuses on the development of the growth of high-quality, single crystal n-type ZnO films, control of n-type conductivity, as well as its application as a transparent contact material in GaN-based devices. The first part of this dissertation is an extensive heteroepitaxial and homoepitaxial growth study presenting the properties of ZnO(0001) layers grown on GaN(0001) templates and ZnO(0001) substrates. We show that deposition on GaN requires a two-step growth technique involving the growth of a low temperature nucleation layer before growing a high temperature epitaxial layer in order to obtain smooth ZnO films with excellent crystal quality and step-flow surface morphology. We obtained homoepitaxial ZnO(0001) films of structural quality and surface morphology that is comparable to the as-received substrates, and showed that a high growth temperature (≥1000°C) is needed in order to achieve step-flow growth mode. We performed n-type doping experiments, and established the conditions for which Indium effectively controls the n-type conductivity of ZnO films grown on GaN(0001) templates. A peak carrier concentration of 3.22x 10 19cm-3 and minimum sheet resistance of 97 O/square was achieved, while simultaneously maintaining good morphology and crystal quality. Finally, we present In-doped ZnO films implemented as p-contacts for GaN-based solar cells and LEDs

  13. Subcritical switching dynamics and humidity effects in nanoscale studies of domain growth in ferroelectric thin films

    International Nuclear Information System (INIS)

    Blaser, Cédric; Paruch, Patrycja

    2015-01-01

    Ferroelectric domain switching in c-axis-oriented epitaxial Pb(Zr 0.2 Ti 0.8 )O 3 thin films was studied using biased scanning probe microscopy tips. While linear and logarithmic dependence of domain size on tip bias and writing time, respectively, are well known, we report an additional linear dependence on relative humidity in the 28–65% range. We map out the switched domain size as a function of both the tip bias and the applied pulse time and describe a growth-limited regime for very short pulses and a nucleation-limited regime for very low tip bias. Using ‘interrupted-switching’ measurements, we probe the nucleation regime with subcritical pulses and identify a surprisingly long relaxation time on the order of 100 ms, which we relate to ionic redistribution both on the surface and within the thin film itself. (paper)

  14. Heteroepitaxial Growth of Ferromagnetic MnSb(0001) Films on Ge/Si(111) Virtual Substrates.

    Science.gov (United States)

    Burrows, Christopher W; Dobbie, Andrew; Myronov, Maksym; Hase, Thomas P A; Wilkins, Stuart B; Walker, Marc; Mudd, James J; Maskery, Ian; Lees, Martin R; McConville, Christopher F; Leadley, David R; Bell, Gavin R

    2013-11-06

    Molecular beam epitaxial growth of ferromagnetic MnSb(0001) has been achieved on high quality, fully relaxed Ge(111)/Si(111) virtual substrates grown by reduced pressure chemical vapor deposition. The epilayers were characterized using reflection high energy electron diffraction, synchrotron hard X-ray diffraction, X-ray photoemission spectroscopy, and magnetometry. The surface reconstructions, magnetic properties, crystalline quality, and strain relaxation behavior of the MnSb films are similar to those of MnSb grown on GaAs(111). In contrast to GaAs substrates, segregation of substrate atoms through the MnSb film does not occur, and alternative polymorphs of MnSb are absent.

  15. Growth of Ba-hexaferrite films on single crystal 6-H SiC

    International Nuclear Information System (INIS)

    Chen Zhoahui; Yang, Aria; Yoon, S.D.; Ziemer, Katherine; Vittoria, Carmine; Harris, V.G.

    2006-01-01

    Barium hexaferrite films have been processed by pulsed laser deposition on single crystal 6-H silicon carbide substrates. Atomic force microscopy images show hexagonal crystals (∼0.5μm in diameter) oriented with the c-axis perpendicular to the film plane. X-ray θ-2θ diffraction measurements indicate a strong (0,0,2n) alignment of crystallites. The magnetization for low-pressure deposition (20mTorr) is comparable to bulk values (4πM s ∼4320G). The loop squareness, important for self-bias microwave device applications, increases with oxygen pressure reaching a maximum value of 70%. This marks the first growth of a microwave ferrite on SiC substrates and offers a new approach in the design and development of μ-wave and mm-wave monolithic integrated circuits. c integrated circuits

  16. [Total body composition in adult patients with growth hormone deficiency before and after its administration].

    Science.gov (United States)

    Weiss, V; Krsek, M; Marek, J; Stĕpán, J; Malík, J

    2003-08-01

    Effect of growth hormone (GH) on the growth and development of children is generally known. Effects of GH in adults are favorable, though. The aim of the work was to verify effects of GH administration on body composition in adult patients with GH deficit (GHD). The authors examined 15 adult patients with GHD originated in 13 of them in adulthood and in two of them in childhood. Their mean age was 43.9 +/- 11.3 years, the mean body mass was 80.0 +/- 15.2 kg. The GH deficit was verified by the stimulation insulin tolerance test. For the period of 12 months, they were subcutaneously administered recombinant human GH in a substitution dose of 0.5 to 1.5 IU/m2 body surface/day. A stable substitution of the hormone was applied for the period of at least six months in all these patients provided any deficit of other hormones had not been demonstrated. The examination by whole-body dosimeter Lunar DPX-L was made in the patients before the GH treatment began and after 12 months of therapy. It enabled to determine the amount of lean body mass (LBM) and fatty mass. After 12 months of GH treatment the mean level of insulin-like growth factor (IGF-I) was increased (P = 0.002). A statistically significant increase of total LBM (48.6 +/- 9.8 vs. 50.8 +/- 9.9 kg, P = 0.004) developed, the fatty mass did not change. Nine of these 15 patients were further followed and the administration of GH proceeded for six months. The densitometric examination was repeated, but no change of LBM was observed. The administration of GH was halted and after the period of 12 months the whole-body densitometric examination was done. The increase of LBM lasted. The amount of fat mass did not change, a decrease of fatty mass was observed after the GH administration ended. After 12 months of GH treatment there was also an increase of maximal output reached on bicycle ergometer (157.3 +/- 34.2 vs. 197.5 +/- 68.1 W, P = 0.006). A positive correlation between LBM and maximal output reached on bicycle

  17. Intermediate surface structure between step bunching and step flow in SrRuO3 thin film growth

    Science.gov (United States)

    Bertino, Giulia; Gura, Anna; Dawber, Matthew

    We performed a systematic study of SrRuO3 thin films grown on TiO2 terminated SrTiO3 substrates using off-axis magnetron sputtering. We investigated the step bunching formation and the evolution of the SRO film morphology by varying the step size of the substrate, the growth temperature and the film thickness. The thin films were characterized using Atomic Force Microscopy and X-Ray Diffraction. We identified single and multiple step bunching and step flow growth regimes as a function of the growth parameters. Also, we clearly observe a stronger influence of the step size of the substrate on the evolution of the SRO film surface with respect to the other growth parameters. Remarkably, we observe the formation of a smooth, regular and uniform ``fish skin'' structure at the transition between one regime and another. We believe that the fish skin structure results from the merging of 2D flat islands predicted by previous models. The direct observation of this transition structure allows us to better understand how and when step bunching develops in the growth of SrRuO3 thin films.

  18. Surface characterization of selected polymer thin films by total-reflection x-ray fluorescence spectroscopy and x-ray reflectivity

    International Nuclear Information System (INIS)

    Innis, Vallerie Ann A.

    2006-01-01

    Development of available x-ray characterizations tools for grazing incidence techniques was done to be able to probe nano-size thin films. Alignment of a Philips x-ray powder diffractometer was improved to let it perform as an x-ray reflectometer. X-ray reflectometry was coupled with total-reflection x-ray fluorescence spectroscopy. Evaluation of the performance of this grazing incidence techniques was done by preparing polymer thin films of carboxymethylcellulose, carrageenan and polyvinylpyrrolidone (PVP). The thickness of the films were varied by varying the process parameters such as concentration, spin speed and spin time. Angle-dispersive total-reflection x-ray fluorescence spectroscopy profiles of three films showed film formation only in carrageenan and PVP. For both carrageenan and PVP, an increase in concentration yielded a corresponding increase in intensity of the fluorescent or scattered peaks. XRR profiles of carrageenan thin films yielded a mean value for the critical angle close to quartz substrate. Thickness measurements of the prepared carrageenan thin films showed that concentration was the main determinant for final film thickness over the other process parameters. Sulfur fluorescent intensity derived from the TXRF measurement showed a linear relationship with the measured thickness by XRR. For PVP, measured critical angle is lower than quartz. Poor adhesion of the polymer onto the substrate yielded a limited number of thickness measurements made from the XRR profiles. (Author)

  19. Growth and structural properties of reactively co-sputtered CIGS films and their solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeha [Cheongju University, Cheongju (Korea, Republic of); Park, Nae-Man [Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of)

    2014-02-15

    Using reactive sputtering, we fabricated stoichiometric CuIn{sub 1-x}Ga{sub x}Se{sub 2} (CIGS) thin films. Both Cu{sub 0.6}Ga{sub 0.4} (CuGa) and Cu{sub 0.4}In{sub 0.6} (CuIn) alloy targets were simultaneously sputtered under the delivery of elemental Se produced from a thermal cracker. By changing the sputtering rates of the CuGa and the CuIn, we were able to obtain the composition ratios of Cu/(Ga+In) and Ga/(Ga+In) in the range of 0.71-0.95 and 0.10-0.30, respectively. Both the grain size and the surface roughness of the CIGS film increased as the Cu/(Ga+In) ratio increased. In the X-ray diffraction analysis on CIGS films of 0.9 m, preferential growth with a [112] orientation was found, and reflections from the (211), (220)/(204), (301), (312)/(116), (400)/(008), and (332)/(316) planes were observed. The CIGS films showed the existence of Cu{sub 2-x}Se phases in the Cu-rich samples and ordered defect compound (ODC) phases in the Cu-poor films, as confirmed in the Raman measurements. A best device performance of η = 8.1%, V{sub oc} = 0.442 V, J{sub sc} = 34.3 mA/cm{sup 2}, and FF = 53.4% was obtained from a cell fabricated with a CIGS layer (t = 0.9 μm) with the Cu/(Ga+In) ratio = 0.71 and the Ga/(Ga+In) ratio = 0.10.

  20. Effect of growth stages on total phenolics content and antioxidant activity of Fumaria vaillantii L.

    Directory of Open Access Journals (Sweden)

    L. Mehdizadeh*

    2017-11-01

    Full Text Available Background and objectives: Plant extracts and their constituents are known to exert biological effects, especially antioxidant activity. Fumaria vaillantii (Fumariaceae has several therapeutic effects in traditional medicine. Antioxidants are able to protect the human body from oxidative damage connected to the reaction of free radicals. Synthetic antioxidants have toxic and carcinogenic effects on human health; therefore, their application has been limited. Thus, there has been an increasing interest in the natural antioxidant compounds to prevent the foods from deterioration. In this study, the antioxidant activity of F. vaillantii extracts at three stages of growth has been evaluated. Methods: The ethanol extracts from the aerial parts of the plants at different phenological stages were prepared and the total phenolics content was determined by Folin-Ciocalteu reagent. Also, the antioxidant activity were determined by three methods as 2,2-diphenyl-1-picrylhydrazyl (DPPH, ferric-ion reducing antioxidant power (FRAP and phosphomolybdenum complex tests. All experiments were carried out in triplicate, and data were subjected to ANOVA according to the SAS software. Results: Total phenolics content of vegetative, budding and flowering stages were 68.38, 71.11 and 56.42 mg GAE/g extract, respectively. Although flowering stage showed the highest antioxidant activity in phosphomolybdenum complex, in DPPH and FRAP methods, it decreased from vegetative to flowering stages. Conclusion: According to the results, the Iranian F. vaillantii extract from vegetative stage was a potential source of natural antioxidants for food and pharmaceutical industries that can be used in different industries.

  1. Insulin-Like Growth Factor 1 Mitigates Hematopoietic Toxicity After Lethal Total Body Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Dunhua; Deoliveira, Divino; Kang, Yubin; Choi, Seung S. [Department of Medicine, Duke University Medical Center, Durham, North Carolina (United States); Li, Zhiguo [Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, North Carolina (United States); Chao, Nelson J. [Department of Medicine, Duke University Medical Center, Durham, North Carolina (United States); Department of Pathology, Duke University Medical Center, Durham, North Carolina (United States); Department of Immunology, Duke University Medical Center, Durham, North Carolina (United States); Duke Cancer Institute, Duke University Medical Center, Durham, North Carolina (United States); Chen, Benny J., E-mail: chen0032@mc.duke.edu [Duke Cancer Institute, Duke University Medical Center, Durham, North Carolina (United States); Department of Medicine, Duke University Medical Center, Durham, North Carolina (United States)

    2013-03-15

    Purpose: To investigate whether and how insulin-like growth factor 1 (IGF-1) mitigates hematopoietic toxicity after total body irradiation. Methods and Materials: BALB/c mice were irradiated with a lethal dose of radiation (7.5 Gy) and treated with IGF-1 at a dose of 100 μg/dose intravenously once a day for 5 consecutive days starting within 1 hour after exposure. Survival and hematopoietic recovery were monitored. The mechanisms by which IGF-1 promotes hematopoietic recovery were also studied by use of an in vitro culture system. Results: IGF-1 protected 8 of 20 mice (40%) from lethal irradiation, whereas only 2 of 20 mice (10%) in the saline control group survived for more than 100 days after irradiation. A single dose of IGF-1 (500 μg) was as effective as daily dosing for 5 days. Positive effects were noted even when the initiation of treatment was delayed as long as 6 hours after irradiation. In comparison with the saline control group, treatment with IGF-1 significantly accelerated the recovery of both platelets and red blood cells in peripheral blood, total cell numbers, hematopoietic stem cells, and progenitor cells in the bone marrow when measured at day 14 after irradiation. IGF-1 protected both hematopoietic stem cells and progenitor cells from radiation-induced apoptosis and cell death. In addition, IGF-1 was able to facilitate the proliferation and differentiation of nonirradiated and irradiated hematopoietic progenitor cells. Conclusions: IGF-1 mitigates radiation-induced hematopoietic toxicity through protecting hematopoietic stem cells and progenitor cells from apoptosis and enhancing proliferation and differentiation of the surviving hematopoietic progenitor cells.

  2. Insulin-Like Growth Factor 1 Mitigates Hematopoietic Toxicity After Lethal Total Body Irradiation

    International Nuclear Information System (INIS)

    Zhou, Dunhua; Deoliveira, Divino; Kang, Yubin; Choi, Seung S.; Li, Zhiguo; Chao, Nelson J.; Chen, Benny J.

    2013-01-01

    Purpose: To investigate whether and how insulin-like growth factor 1 (IGF-1) mitigates hematopoietic toxicity after total body irradiation. Methods and Materials: BALB/c mice were irradiated with a lethal dose of radiation (7.5 Gy) and treated with IGF-1 at a dose of 100 μg/dose intravenously once a day for 5 consecutive days starting within 1 hour after exposure. Survival and hematopoietic recovery were monitored. The mechanisms by which IGF-1 promotes hematopoietic recovery were also studied by use of an in vitro culture system. Results: IGF-1 protected 8 of 20 mice (40%) from lethal irradiation, whereas only 2 of 20 mice (10%) in the saline control group survived for more than 100 days after irradiation. A single dose of IGF-1 (500 μg) was as effective as daily dosing for 5 days. Positive effects were noted even when the initiation of treatment was delayed as long as 6 hours after irradiation. In comparison with the saline control group, treatment with IGF-1 significantly accelerated the recovery of both platelets and red blood cells in peripheral blood, total cell numbers, hematopoietic stem cells, and progenitor cells in the bone marrow when measured at day 14 after irradiation. IGF-1 protected both hematopoietic stem cells and progenitor cells from radiation-induced apoptosis and cell death. In addition, IGF-1 was able to facilitate the proliferation and differentiation of nonirradiated and irradiated hematopoietic progenitor cells. Conclusions: IGF-1 mitigates radiation-induced hematopoietic toxicity through protecting hematopoietic stem cells and progenitor cells from apoptosis and enhancing proliferation and differentiation of the surviving hematopoietic progenitor cells

  3. EuO and Gd-doped EuO thin films. Epitaxial growth and properties

    International Nuclear Information System (INIS)

    Sutarto, Ronny

    2009-01-01

    quality of many of the doped EuO samples used in the past bulk studies. The focus of this thesis is on the preparation and the properties of high-quality single-crystalline EuO and Gd-doped EuO thin films. The so-called Eu-distillation-assisted molecular beam epitaxy (MBE) has been employed to achieve full control of the stoichiometry. The films have been epitaxially grown on yttria-stabilized cubic zirconia (YSZ) (001) substrates. By a systematic variation of the oxygen deposition rates, we have been able to observe sustained oscillations in the intensity of the reflection high-electron energy diffraction (RHEED) pattern during growth. We thus have demonstrated that layer-by-layer growth has been achieved for the first time. We also have confirmed that YSZ indeed supplies oxygen during the initial stages of growth, yet the EuO stoichiometry can still be well maintained. In the case of Gd-doped EuO films, the presence of Gd even helps to stabilize the layer-by-layer growth mode. It is important to achieve this growth mode, since it enables the preparation of films with very smooth and at surfaces. This in turn facilitates the capping of the films with a thin Al overlayer in order to protect the films against degradation under ambient conditions. More important, the smoothness of the lm will enable the preparation of high quality device structures. By using ex-situ soft x-ray absorption spectroscopy (XAS) at the Eu and Gd M 4,5 edges, we have confirmed that the films are completely free from Eu 3+ contaminants, and we were able to determine reliably the actual Gd concentration. This actual Gd concentration could in fact significantly deviate from the nominal Gd/Eu evaporation ratio. From magnetization and susceptibility measurements, we found the Curie temperature to increase smoothly as a function of doping from 69 K up to a maximum of 125 K, all with a saturation moment of 7 μB. A threshold behavior was not observed for Gd concentrations as low as 0.2 %. Analysis of the

  4. EuO and Gd-doped EuO thin films. Epitaxial growth and properties

    Energy Technology Data Exchange (ETDEWEB)

    Sutarto, Ronny

    2009-07-06

    this respect the quality of many of the doped EuO samples used in the past bulk studies. The focus of this thesis is on the preparation and the properties of high-quality single-crystalline EuO and Gd-doped EuO thin films. The so-called Eu-distillation-assisted molecular beam epitaxy (MBE) has been employed to achieve full control of the stoichiometry. The films have been epitaxially grown on yttria-stabilized cubic zirconia (YSZ) (001) substrates. By a systematic variation of the oxygen deposition rates, we have been able to observe sustained oscillations in the intensity of the reflection high-electron energy diffraction (RHEED) pattern during growth. We thus have demonstrated that layer-by-layer growth has been achieved for the first time. We also have confirmed that YSZ indeed supplies oxygen during the initial stages of growth, yet the EuO stoichiometry can still be well maintained. In the case of Gd-doped EuO films, the presence of Gd even helps to stabilize the layer-by-layer growth mode. It is important to achieve this growth mode, since it enables the preparation of films with very smooth and at surfaces. This in turn facilitates the capping of the films with a thin Al overlayer in order to protect the films against degradation under ambient conditions. More important, the smoothness of the lm will enable the preparation of high quality device structures. By using ex-situ soft x-ray absorption spectroscopy (XAS) at the Eu and Gd M{sub 4,5} edges, we have confirmed that the films are completely free from Eu{sup 3+} contaminants, and we were able to determine reliably the actual Gd concentration. This actual Gd concentration could in fact significantly deviate from the nominal Gd/Eu evaporation ratio. From magnetization and susceptibility measurements, we found the Curie temperature to increase smoothly as a function of doping from 69 K up to a maximum of 125 K, all with a saturation moment of 7 {mu}B. A threshold behavior was not observed for Gd concentrations

  5. The growth, characterization, and application of highly ordered small molecule semiconducting thin films

    Science.gov (United States)

    Lunt, Richard Royal, III

    Organic semiconductors have gained tremendous attention recently as their use in field effect transistors, sensors, solar cells, lasers, and organic light emitting diodes have been demonstrated, offering the potential for low-cost alternatives. Since renewable energy remains one the greatest challenges of the 21st century, the possibility for low-cost and flexible organic photovoltaics is particularly exciting. In the first part of this thesis, we demonstrate a route to the controlled growth of oriented crystalline films through organic vapor-phase deposition (OVPD), in conjunction with organic-inorganic, and organic-organic quasi-epitaxy. This method for producing highly ordered crystalline thin-film heterostructures combines the control of film growth with the electronic properties expected to approach that of organic single crystals, making them potentially useful for high efficiency organic thin-film devices and solar cells. We further demonstrate OVPD as a method for the deposition of large-scale organic electronics with low material waste, a key ability in fulfilling the promise of low-cost organic devices. The second part of this thesis is focused on understanding factors that govern energy (i.e. exciton) transport. The two single most important and fundamental properties of organic semiconductors are the transport of charge and energy. While charge mobility has been extensively studied and convincingly linked to the degree of crystalline order and orientation, the principles governing energy transport, i.e. exciton migration, in this class of materials and the subsequent connection to crystalline properties still remain ambiguous. Therefore, we aim to understand key aspects governing exciton motion in organic materials to better engineer materials, film morphologies, and film architectures for organic electronics with improved performance. To this end, we have developed a new method for measuring exciton diffusion and characterize a range of archetypal

  6. The effect of deposition energy of energetic atoms on the growth and structure of ultrathin amorphous carbon films studied by molecular dynamics simulations

    KAUST Repository

    Wang, N; Komvopoulos, K

    2014-01-01

    The growth and structure of ultrathin amorphous carbon films was investigated by molecular dynamics simulations. The second-generation reactive-empirical-bond-order potential was used to model atomic interactions. Films with different structures

  7. Hydrothermal Growth of Quasi-Monocrystal ZnO Thin Films and Their Application in Ultraviolet Photodetectors

    Directory of Open Access Journals (Sweden)

    Yung-Chun Tu

    2015-01-01

    Full Text Available Quasi-monocrystal ZnO film grown using the hydrothermal growth method is used for the fabrication of Cu2O/ZnO heterojunction (HJ ultraviolet photodetectors (UV-PDs. The HJ was formed via the sputtering deposition of p-type Cu2O onto hydrothermally grown ZnO film (HTG-ZnO-film. The effect of annealing temperature in the nitrogen ambient on the photoluminescence spectra of the synthesized ZnO film was studied. The optoelectronic properties of Cu2O/ZnO film with various Cu2O thicknesses (250–750 nm under UV light (365 nm; intensity: 3 mW/cm2 were determined. The UV sensitivity of the HTG-ZnO-film-based UV-PDs and the sputtered ZnO-film-based UV-PDs were 55.6-fold (SHTG and 8.8-fold (Ssputter, respectively. The significant gain in sensitivity (SHTG/Ssputter = 630% of the proposed ZnO-film-based device compared to that for the device based on sputtered film can be attributed to the improved photoelectric properties of quasi-monocrystal ZnO film.

  8. Room temperature growth of nanocrystalline anatase TiO{sub 2} thin films by dc magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Preetam, E-mail: preetamphy@gmail.co [Functional Nanomaterials Research Lab, Department of Physics and Centre of Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Kaur, Davinder [Functional Nanomaterials Research Lab, Department of Physics and Centre of Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2010-03-01

    We report, the structural and optical properties of nanocrystalline anatase TiO{sub 2} thin films grown on glass substrate by dc magnetron sputtering at room temperature. The influence of sputtering power and pressure over crystallinity and surface morphology of the films were investigated. It was observed that increase in sputtering power activates the TiO{sub 2} film growth from relative lower surface free energy to higher surface free energy. XRD pattern revealed the change in preferred orientation from (1 0 1) to (0 0 4) with increase in sputtering power, which is accounted for different surface energy associated with different planes. Microstructure of the films also changes from cauliflower type to columnar type structures with increase in sputtering power. FESEM images of films grown at low pressure and low sputtering power showed typical cauliflower like structure. The optical measurement revealed the systematic variation of the optical constants with deposition parameters. The films are highly transparent with transmission higher than 90% with sharp ultraviolet cut off. The transmittance of these films was found to be influenced by the surface roughness and film thickness. The optical band gap was found to decrease with increase in the sputtering power and pressure. The refractive index of the films was found to vary in the range of 2.50-2.24 with increase in sputtering pressure or sputtering power, resulting in the possibility of producing TiO{sub 2} films for device applications with different refractive index, by changing the deposition parameters.

  9. Growth and characterization of tris(8-hydroxyquinoline)-aluminum molecular films

    Energy Technology Data Exchange (ETDEWEB)

    Jan, Da-Jeng; Wang, Sheng-Shin; Tang, Shiow-Jing; Lin, Ku-Yen; Yang, Jiun-Jie; Shen, Ji-Lin; Chiu, Kuan-Cheng, E-mail: kcchiu@cycu.edu.tw

    2011-11-30

    Various tris(8-hydroxyquinoline)-aluminum (Alq3) molecular solid films were grown on top of indium-tin-oxide (ITO) glass substrates using physical vapor deposition. The effect of changing the growth conditions on the properties of the films was studied. From scanning electron microscopy, an Alq3 planar layer over an ITO-substrate was observed at the initial period, and an Alq3 tubular structure (which becomes dominant at substrate temperature T{sub sub} Greater-Than-Over-Equal-To 90 Degree-Sign C) was found to nucleate from this layer. From X-ray diffraction, the Alq3 planar layer possesses an amorphous character while the Alq3 tubular layer has a triclinic {alpha}-phase structure. Based on an Arrhenius plot of the growth rate versus 1/T{sub sub}, the growth behaviors in various T{sub sub}-regions were discussed to be dominated by adhesion (for T{sub sub} < 90 Degree-Sign C), steric effect (90 Degree-Sign C < T{sub sub} < 150 Degree-Sign C), and re-evaporation (T{sub sub} > 150 Degree-Sign C). Then, from optical transmission and photoluminescence spectra performed on the high crystalline Alq3 films, two signals associated with the optical-bandgap E{sub g} absorption and the gap-state absorption were determined and discussed in terms of the optical properties of the constituent Alq3 molecules. Finally, from a fit of E{sub g}(T) by an effective electron-phonon interaction model, the physical significance of these fitting parameters for the Alq3 molecular solid was investigated.

  10. Growth of Ag thin films on ZnO(0 0 0 -1) investigated by AES and STM

    Energy Technology Data Exchange (ETDEWEB)

    Duriau, E. [Interuniversity Microelectronic Center (IMEC), SPDT-MCA, Kapeldreef 75, B-3001 Leuven (Belgium); Agouram, S. [Dpto. Fisica Aplicada y Electromagnetismo c/Dr. Moliner no. 50, 46100 Burjassot, Valencia (Spain); Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Morhain, C. [Centre de Recherche sur l' HeteroEpitaxie et ses Applications (CRHEA), CNRS, Rue Bernard Gregory, F-06560 Valbonne Sophia-Antipolis (France); Seldrum, T. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Sporken, R. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Dumont, J. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium)]. E-mail: jacques.dumont@fundp.ac.be

    2006-11-15

    The growth of Ag films on ZnO(0 0 0 -1) has been investigated by Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). A high density of islands is nucleated at the earliest stages of the growth. An upstepping mechanism causes these islands to coalesce while the uncovered fraction of the ZnO surface remains constant (30%)

  11. Growth Rate and Morphology of a Single Calcium Carbonate Crystal on Polysulfone Film Measured with Time Lapse Raman Micro Spectroscopy

    NARCIS (Netherlands)

    Liszka, B.; Lenferink, Aufrid T.M.; Otto, Cornelis

    2016-01-01

    The growth of single, self- nucleated calcium carbonate crystals on a polysulfone (PSU) film was investigated with high resolution, time lapse Raman imaging. The Raman images were acquired on the interface of the polymer with the crystal. The growth of crystals could thus be followed in time. PSU is

  12. Growth Kinetics and Oxidation Mechanism of ALD TiN Thin Films Monitored by In Situ Spectroscopic Ellipsometry

    NARCIS (Netherlands)

    Van Hao, B.; Groenland, A.W.; Aarnink, Antonius A.I.; Wolters, Robertus A.M.; Schmitz, Jurriaan; Kovalgin, Alexeij Y.

    2011-01-01

    Spectroscopic ellipsometry (SE) was employed to investigate the growth of atomic layer deposited (ALD) TiN thin films from titanium chloride (TiCl4) and ammonia (NH3) and the followed oxidation in dry oxygen. Two regimes were found in the growth including a transient stage prior to a linear regime.

  13. Molecular beam epitaxy growth of InSb1-xBix thin films

    DEFF Research Database (Denmark)

    Yuxin Song; Shumin Wang; Saha Roy, Ivy

    2013-01-01

    Molecular beam epitaxy growth for InSb1-xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology are stu...

  14. Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Galloway, H.C.

    1995-12-01

    Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides

  15. Growth and luminescence properties of Pr3+-doped single crystalline films of garnets and perovskites

    International Nuclear Information System (INIS)

    Gorbenko, V.; Zorenko, Yu.; Savchyn, V.; Zorenko, T.; Pedan, A.; Shkliarskyi, V.

    2010-01-01

    Peculiarities of growth of single crystalline films (SCF) of Pr 3+ doped Y 3 Al 5 O 12 and Lu 3 Al 5 O 12 garnets and YAlO 3 and LuAlO 3 perovskites by the liquid phase epitaxy method from melt-solutions based on PbO-B 2 O 3 flux as well as luminescent and scintillation properties of these SCFs were studied in this work. Dependence the intensity of the Pr 3+ d-f and f-f-luminescence on the activator concentration and influence of Pb 2+ flux dopant on the light yield of SCFs of the mentioned garnets and perovskites were analyzed.

  16. Catalyst growth of single crystal aligned ZnO nanorods on ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dongxu; Andreazza, Caroline; Andreazza, Pascal [Centre de Recherche sur la Matiere Divisee, CNRS-Universite d' Orleans, 1b rue de la Ferollerie, 45071 Orleans cedex 2 (France)

    2005-02-01

    One dimensional ZnO nanorods were successfully fabricated on Si substrates via a simple physical vapor-phase transport method at 950 C. A ZnO shell covered Au/Zn alloy is assumed as the nucleation site, then ZnO nanorods grow following a vapor-solid (VS) process. In order to guide the nanorod growth a c-axis oriented ZnO thin film and Au catalyst were first deposited on Si (100) surface. SEM images show nanorods grown on this substrate are vertical to the substrate surface. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Modelling the growth process of porous aluminum oxide film during anodization

    International Nuclear Information System (INIS)

    Aryslanova, E M; Alfimov, A V; Chivilikhin, S A

    2015-01-01

    Currently it has become important for the development of metamaterials and nanotechnology to obtain regular self-assembled structures. One such structure is porous anodic alumina film that consists of hexagonally packed cylindrical pores. In this work we consider the anodization process, our model takes into account the influence of layers of aluminum and electrolyte on the rate of growth of aluminum oxide, as well as the effect of surface diffusion. In present work we consider those effects. And as a result of our model we obtain the minimum distance between centers of alumina pores in the beginning of anodizing process. (paper)

  18. Modelling the growth process of porous aluminum oxide film during anodization

    Science.gov (United States)

    Aryslanova, E. M.; Alfimov, A. V.; Chivilikhin, S. A.

    2015-11-01

    Currently it has become important for the development of metamaterials and nanotechnology to obtain regular self-assembled structures. One such structure is porous anodic alumina film that consists of hexagonally packed cylindrical pores. In this work we consider the anodization process, our model takes into account the influence of layers of aluminum and electrolyte on the rate of growth of aluminum oxide, as well as the effect of surface diffusion. In present work we consider those effects. And as a result of our model we obtain the minimum distance between centers of alumina pores in the beginning of anodizing process.

  19. Growth of thin films of TiN on MgO(100) monitored by high-pressure RHEED

    DEFF Research Database (Denmark)

    Pryds, Nini; Cockburn, D.; Rodrigo, Katarzyna Agnieszka

    2008-01-01

    Reflection high-energy electron diffraction (RHEED) operated at high pressure has been used to monitor the initial growth of titanium nitride (TiN) thin films on single-crystal (100) MgO substrates by pulsed laser deposition (PLD). This is the first RHEED study where the growth of TiN films...... electron microscopy. These observations are in good agreement with the three-dimensional Volmer-Weber growth type, by which three-dimensional crystallites are formed and later cause a continuous surface roughening. This leads to an exponential decrease in the intensity of the specular spot in the RHEED...

  20. Advection-diffusion model for normal grain growth and the stagnation of normal grain growth in thin films

    International Nuclear Information System (INIS)

    Lou, C.

    2002-01-01

    An advection-diffusion model has been set up to describe normal grain growth. In this model grains are divided into different groups according to their topological classes (number of sides of a grain). Topological transformations are modelled by advective and diffusive flows governed by advective and diffusive coefficients respectively, which are assumed to be proportional to topological classes. The ordinary differential equations governing self-similar time-independent grain size distribution can be derived analytically from continuity equations. It is proved that the time-independent distributions obtained by solving the ordinary differential equations have the same form as the time-dependent distributions obtained by solving the continuity equations. The advection-diffusion model is extended to describe the stagnation of normal grain growth in thin films. Grain boundary grooving prevents grain boundaries from moving, and the correlation between neighbouring grains accelerates the stagnation of normal grain growth. After introducing grain boundary grooving and the correlation between neighbouring grains into the model, the grain size distribution is close to a lognormal distribution, which is usually found in experiments. A vertex computer simulation of normal grain growth has also been carried out to make a cross comparison with the advection-diffusion model. The result from the simulation did not verify the assumption that the advective and diffusive coefficients are proportional to topological classes. Instead, we have observed that topological transformations usually occur on certain topological classes. This suggests that the advection-diffusion model can be improved by making a more realistic assumption on topological transformations. (author)

  1. The effect of chitosan and whey proteins-chitosan films on the growth of Penicillium expansum in apples.

    Science.gov (United States)

    Simonaitiene, Dovile; Brink, Ieva; Sipailiene, Ausra; Leskauskaite, Daiva

    2015-05-01

    Penicillium expansum causes a major post-harvest disease of apples. The aim of this study was to investigate the inhibition effect of chitosan and whey proteins-chitosan films containing different amounts of quince and cranberry juice against P. expansum on the simulation medium and on apples. The mechanical properties of films were also evaluated. The presence of cranberry and quince juice in the composition of chitosan and whey proteins-chitosan films caused a significant (P ≤ 0.05) increase in elasticity and decrease in tensile strength of films. Chitosan and whey proteins-chitosan films with quince and cranberry juice demonstrated a significant (P ≤ 0.05) inhibition effect against P. expansum growth on the simulated medium and apples. The presence of cranberry juice in the composition of chitosan and whey proteins-chitosan films resulted in a longer lag phase and a lower P. expansum growth rate on the simulation medium in comparison with films made with the addition of quince juice. These differences were not evident when experiment was conducted with apples. Addition of quince and cranberry juice to the chitosan and whey proteins-chitosan films as natural antifungal agents has some potential for prolonging the shelf life of apples. © 2014 Society of Chemical Industry.

  2. Epitaxial growth of fcc-CoxNi100-x thin films on MgO(110) single-crystal substrates

    International Nuclear Information System (INIS)

    Ohtake, Mitsuru; Nukaga, Yuri; Sato, Yoichi; Futamoto, Masaaki; Kirino, Fumiyoshi

    2009-01-01

    Co x Ni 100-x (x=100, 80, 20, 0 at. %) epitaxial thin films were prepared on MgO(110) single-crystal substrates heated at 300 deg. C by ultrahigh vacuum molecular beam epitaxy. The growth mechanism is discussed based on lattice strain and crystallographic defects. CoNi(110) single-crystal films with a fcc structure are obtained for all compositions. Co x Ni 100-x film growth follows the Volmer-Weber mode. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of the Co x Ni 100-x films are in agreement within ±0.5% with the values of the respective bulk Co x Ni 100-x crystals, suggesting that the strain in the film is very small. High-resolution cross-sectional transmission microscopy shows that an atomically sharp boundary is formed between a Co(110) fcc film and a MgO(110) substrate, where periodical misfit dislocations are preferentially introduced in the film at the Co/MgO interface. The presence of such periodical misfit dislocations relieves the strain caused by the lattice mismatch between the film and the substrate.

  3. Preferential growth of short aligned, metallic-rich single-walled carbon nanotubes from perpendicular layered double hydroxide film.

    Science.gov (United States)

    Zhao, Meng-Qiang; Tian, Gui-Li; Zhang, Qiang; Huang, Jia-Qi; Nie, Jing-Qi; Wei, Fei

    2012-04-07

    Direct bulk growth of single-walled carbon nanotubes (SWCNTs) with required properties, such as diameter, length, and chirality, is the first step to realize their advanced applications in electrical and optical devices, transparent conductive films, and high-performance field-effect transistors. Preferential growth of short aligned, metallic-rich SWCNTs is a great challenge to the carbon nanotube community. We report the bulk preferential growth of short aligned SWCNTs from perpendicular Mo-containing FeMgAl layered double hydroxide (LDH) film by a facile thermal chemical vapor deposition with CH(4) as carbon source. The growth of the short aligned SWCNTs showed a decreased growth velocity with an initial value of 1.9 nm s(-1). Such a low growth velocity made it possible to get aligned SWCNTs shorter than 1 μm with a growth duration less than 15 min. Raman spectra with different excitation wavelengths indicated that the as-grown short aligned SWCNTs showed high selectivity of metallic SWCNTs. Various kinds of materials, such as mica, quartz, Cu foil, and carbon fiber, can serve as the substrates for the growth of perpendicular FeMoMgAl LDH films and also the growth of the short aligned SWCNTs subsequently. These findings highlight the easy route for bulk preferential growth of aligned metallic-rich SWCNTs with well defined length for further bulk characterization and applications. This journal is © The Royal Society of Chemistry 2012

  4. Metalorganic chemical vapor deposition of Er{sub 2}O{sub 3} thin films: Correlation between growth process and film properties

    Energy Technology Data Exchange (ETDEWEB)

    Giangregorio, Maria M. [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy)], E-mail: michelaria.giangregorio@ba.imip.cnr.it; Losurdo, Maria; Sacchetti, Alberto; Capezzuto, Pio; Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy)

    2009-02-27

    Er{sub 2}O{sub 3} thin films have been grown by metalorganic chemical vapor deposition (MOCVD) at 600 deg. C on different substrates, including glass, Si (100) and sapphire (0001) using tris(isopropylcyclopentadienyl)erbium and O{sub 2}. The effects of growth parameters such as the substrate, the O{sub 2} plasma activation and the temperature of organometallic precursor injection, on the nucleation/growth kinetics and, consequently, on film properties have been investigated. Specifically, very smooth (111)-oriented Er{sub 2}O{sub 3} thin films (the root mean square roughness is 0.3 nm) are achieved on Si (100), {alpha}-Al{sub 2}O{sub 3} (0001) and amorphous glass by MOCVD. Growth under O{sub 2} remote plasma activation results in an increase in growth rate and in (100)-oriented Er{sub 2}O{sub 3} films with high refractive index and transparency in the visible photon energy range.

  5. Growth and Characterization of Magnetoelectric Fe2TeO6 Thin Films

    Science.gov (United States)

    Wang, Junlei; Colon Santana, Juan; Wu, Ning; Dowben, Peter; Binek, Christian

    2013-03-01

    Voltage-controlled spintronics is of vital importance in information technology where power consumption and Joule heating restrict progress through scaling. Motivated by spintronic concepts and specifically by device applications utilizing electrically controlled interface or boundary magnetization (BM) in magnetic thin film heterostructures, we report on growth, structural, magnetic and magnetoelectric (ME) characterization of the antiferromagnet Fe2TeO6. Magnetometry of synthesized Fe2TeO6 powder, in combination with ME susceptibility data reveals 3D Heisenberg criticality in striking similarity to the archetypical ME chromia. X-ray diffraction shows (110) texture of the PLD grown films. Measurements of the magnetic susceptibility of the latter confirm in-plane magnetic anisotropy. X-ray photoemission spectroscopy indicates a Te-O terminated (110) surface. We interpret it in terms of surface reconstruction. Measurements of X-ray magnetic circular dichroism combined with photoemission electron microscopy support the presence of electrically controllable BM in the PLD-grown Fe2TeO6 thin film. We acknowledge financial support by NSF-MRSEC & Nanoelectronics Research Initiative.

  6. Growth of Ferromagnetic Epitaxial Film of Hexagonal FeGe on (111) Ge Surface

    Science.gov (United States)

    Kumar, Dushyant; Joshi, P. C.; Hossain, Z.; Budhani, R. C.

    2014-03-01

    The realization of semiconductors showing ferromagnetic order at easily accessible temperatures has been of interest due to their potential use in spintronic devices where long spin life times are of key interest. We have realized the growth of FeGe thin films on Ge (111) wafers using pulsed laser deposition (PLD). The stoichiometric and single phase FeGe target used in PLD chamber has been made by arc melting. A typical θ-2 θ diffraction spectra performed on 40 nm thick FeGe film suggests the stabilization of β-Ni2In (B82-type) hexagonal phase with an epitaxial orientation of (0001)FeGe ||(111)Ge and [11-20]FeGe ||[-110]Ge. SEM images shows a granular structure with the formation of very large grains of about 100 to 500 nm in lateral dimension. The magnetization vs. temperature data taken from SQUID reveal the TC of ~ 270K. Since, PLD technique makes it easier to stabilize the B82 (Ni2In) hexagonal phase in thin FeGe films, this work opens opportunities to reinvestigate many conflicting results on various properties of the FeGe system.

  7. Development of luminescent pH sensor films for monitoring bacterial growth through tissue.

    Science.gov (United States)

    Wang, Fenglin; Raval, Yash; Chen, Hongyu; Tzeng, Tzuen-Rong J; DesJardins, John D; Anker, Jeffrey N

    2014-02-01

    Although implanted medical devices (IMDs) offer many benefits, they are susceptible to bacterial colonization and infections. Such infections are difficult to treat because bacteria could form biofilms on the implant surface, which reduce antibiotics penetration and generate local dormant regions with low pH and low oxygen. In addition, these infections are hard to detect early because biofilms are often localized on the surface. Herein, an optical sensor film is developed to detect local acidosis on an implanted surface. The film contains both upconverting particles (UCPs) that serve as a light source and a pH indicator that alters the luminescence spectrum. When irradiated with 980 nm light, the UCPs produce deeply penetrating red light emission, while generating negligible autofluorescence in the tissue. The basic form of the pH indicator absorbs more of upconversion luminescence at 661 nm than at 671 nm and consequently the spectral ratio indicates pH. Implanting this pH sensor film beneath 6-7 mm of porcine tissue does not substantially affect the calibration curve because the peaks are closely spaced. Furthermore, growth of Staphylococcus epidermidis on the sensor surface causes a local pH decrease that can be detected non-invasively through the tissue. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Phase competition in the growth of SrCoOx/LaAlO3 thin films

    Science.gov (United States)

    Zhang, Jie; Meng, Dechao; Huang, Haoliang; Cai, Honglei; Huang, Qiuping; Wang, Jianlin; Yang, Yuanjun; Zhai, Xiaofang; Fu, Zhengping; Lu, Yalin

    2018-02-01

    The reversible topotactic phase transformation between brownmillerite SrCoO2.5 to perovskite SrCoO3 has attracted more and more attention for potential applications as solid oxide fuels and electrolysis cells. However, the relatively easy transformation result from small thermal stable energy barriers between the two phases leads to unstable the structures. In the paper, amounts of SrCoO3-δ films have been prepared by pulsed laser deposition at optimized growth conditions with the temperature range of 590-720°C. The X-ray diffraction (XRD) results demonstrated that a phase competition emerged around 650°C. The Gibbs free energies of two phases at high temperature revealed the difference of stability of these two phases under different growth temperature. The optical spectroscopies and X-ray photoelectron spectroscopies were used to verify the electronic structure and chemical state differences between the two phases with distinct crystal structures.

  9. Peculiarities in film growth of ferroelectric complex oxides in ion-plasma sputtering

    International Nuclear Information System (INIS)

    Mukhortov, V.M.; Golovko, Yu.I.; Mukhortov, Vl.M.; Dudkevich, V.P.

    1981-01-01

    Experimental investigation into the process of complex oxide film growth (using BaTiO 3 and (Ba,Sr)TiO 3 as an example) during ion-plasma sputtering has been carried out. It is shown that neutral excited atoms are knocked out of a ceramic target during its ion bombardment. Removing from the target they loss energy at the expence of collisions and at some distance hsub(cr) the oxidation reaction (BaO, TiO, TiO 2 , SrO) becomes possible. So the ''construction'' material comes in either in the form of atoms or in the form of molecules of simple oxides depending on a distance between cathode and substrate. Two mechanisms of synthesis and crystallization distinguished with dependences of growth rate, elementary cell parameters and other structure characteristics on precipitation temperature correspond to two precipitation mechanisms. Part of re-evaporation and reduction processes is discussed [ru

  10. Growth and structure of Co/Au magnetic thin films; Croissance et structure des couches minces magnetiques Co/Au

    Energy Technology Data Exchange (ETDEWEB)

    Marsot, N

    1999-01-14

    We have studied the growth and the crystallographic structure of magnetic ultra thin cobalt/gold films (Co/Au), in order to investigate the correlations between their magnetic and structural properties. Room temperature (R.T.) Co growth on Au (111) proceeds in three stages. Up to 2 Co monolayers (ML), a bilayer island growth mode is observed. Between 2 and 5 ML, coalescence of the islands occurs, covering the substrate surface and a Co/Au mixing is observed resulting from the de-construction of the Herringbone reconstruction. Finally, beyond 5 ML, the CoAu mixing is buried and the Co growth continues in a 3-D growth. Annealing studies at 600 K on this system show a smoothing effect of the Co film, and at the same time, segregation of Au atoms. The quality of the Co/Au interface (sharpness) is not enhanced by the annealing. The local order was studied by SEXAFS and the long range order by GIXRD showing that the Co film has a hexagonal close packed structure, with an easy magnetization axis perpendicular to the surface. From a local order point of view, the Co grows with an incoherent epitaxy and keeps its own bulk parameters. The GIXRD analysis shows a residual strain in the Co film of 4%. The difference observed between the local order analysis and the long range order results is explained in terms of the low dimensions of the diffracting domains. The evolution of film strains, as a function of the Co coverage, shows a marked deviation from the elastic strain theory. Modification of the strain field in the Co film as a function of the Au coverage is studied by GIXRD analysis. The Au growth study, at R.T., shows no evidence of a Au/Co mixing in the case of the Au/Co interface. The Au overlayer adopts a twinned face centred cubic structure on the rough Co film surface. (author)

  11. Synchrotron x-ray-diffraction study of the structure and growth of Xe films adsorbed on the Ag(111) surface

    International Nuclear Information System (INIS)

    Dai, P.; Wu, Z.; Angot, T.; Wang, S.; Taub, H.; Ehrlich, S.N.

    1999-01-01

    Synchrotron x-ray scattering has been used to investigate the structure and growth of perhaps the simplest of all films: xenon physisorbed on the Ag(111) surface. High-resolution x-ray scans of the in-plane structure and lower-resolution scans (specular and nonspecular) of the out-of-plane order were performed. The Xe films were prepared under both quasiequilibrium and kinetic growth conditions, and have fewer structural defects than those investigated previously by others on graphite substrates. Under quasiequilibrium conditions, the bulk Xe-Xe spacing is reached at monolayer completion, and the monolayer and bilayer lattice constants at coexistence are inferred equal to within 0.005 Angstrom, consistent with theoretical calculations. The Xe/vacuum interface profile for a complete monolayer and bilayer grown at quasiequilibrium is found to be sharper than for kinetically grown films. At coverages above two layers, diffraction scans along the Xe(01l) rod for quasiequilibrated films are consistent with the presence of two domains having predominantly an ABC stacking sequence and rotated 60 degree with respect to each other about the surface normal. Annealing of these films alters neither the population of the two domains nor the fraction of ABA stacking faults. The thickest film grown under quasiequilibrium conditions exceeds 220 Angstrom (resolution limited). Under kinetic growth conditions, x-ray intensity oscillations at the Xe anti-Bragg position of the specular rod are observed as a function of time, indicating nearly layer-by-layer growth. Up to four complete oscillations corresponding to a film of eight layers have been observed before the intensity is damped out; the number of oscillations is found to depend on the substrate temperature, the growth rate, and the quality of the Ag(111) substrate. The specular reflectivity from kinetically grown films at nominal coverages of three and four layers has been analyzed using a Gaussian model which gives a film

  12. Stabilisation of late transition metal and noble metal films in hexagonal and body centred tetragonal phases by epitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Hueger, E.

    2005-08-26

    In this work ultrathin metallic films with a crystal phase different to their natural bulk structure were produced by hetero-epitaxial growth on metallic substrates. A further aim of this work was to understand the initiation, growth and stability of crystal phase modifications of these films. there exist cases where the films turn beyond the pseudomorphic-growth to a crystal phase different from their natural bulk structure. The present work presents and discusses such a case in addition to the general phenomenon of pseudomorphic-growth. In particular it is shown that metals whose natural phase is face centred cubic (fcc) can be grown in body centred tetragonal (bct) or hexagonal close packed (hcp) phases in the form of thin films on (001) surfaces of appropriate substrates. The growth behavior, electron diffraction analysis, appearance conditions, geometric fit considerations, examples and a discussion of the phase stability of non-covered films and superlattices is given reviewing all epitaxial-systems whose diffraction pattern can be explained by the hexagonal or pseudomorphic bct phase. (orig.)

  13. Surviving floods: leaf gas films improve O₂ and CO₂ exchange, root aeration, and growth of completely submerged rice.

    Science.gov (United States)

    Pedersen, Ole; Rich, Sarah Meghan; Colmer, Timothy David

    2009-04-01

    When completely submerged, the leaves of some species retain a surface gas film. Leaf gas films on submerged plants have recently been termed 'plant plastrons', analogous with the plastrons of aquatic insects. In aquatic insects, surface gas layers (i.e. plastrons) enlarge the gas-water interface to promote O₂ uptake when under water; however, the function of leaf gas films has rarely been considered. The present study demonstrates that gas films on leaves of completely submerged rice facilitate entry of O₂ from floodwaters when in darkness and CO₂ entry when in light. O₂ microprofiles showed that the improved gas exchange was not caused by differences in diffusive boundary layers adjacent to submerged leaves with or without gas films; instead, reduced resistance to gas exchange was probably due to the enlarged water-gas interface (cf. aquatic insects). When gas films were removed artificially, underwater net photosynthesis declined to only 20% of the rate with gas films present, such that, after 7 days of complete submergence, tissue sugar levels declined, and both shoot and root growth were reduced. Internal aeration of roots in anoxic medium, when shoots were in aerobic floodwater in darkness or when in light, was improved considerably when leaf gas films were present. Thus, leaf gas films contribute to the submergence tolerance of rice, in addition to those traits already recognized, such as the shoot-elongation response, aerenchyma and metabolic adjustments to O₂ deficiency and oxidative stress. © 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd.

  14. Serum Levels Of Free And Total Insulin-Like Growth Factor (IGF)-1 And IGF Binding Protein-3 In Normal And Growth Hormone Deficient Children

    International Nuclear Information System (INIS)

    Shousha, M.A.; Soliman, S.E.T.; Hafez, M.H.

    2006-01-01

    Serum levels of total insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 (IGFBP-3) reflect the endogenous GH secretion in healthy children, which makes them good diagnostic markers for screening growth hormone deficiency (GHD) in short children, although some controversy still exists. Only a minor fraction of the total IGF-1 circulates in its free form, which is believed to be the biologically active form. Serum levels of free IGF-1, total IGF-I and IGFBP-3 were measured in 144 healthy children (72 boys and 72 girls, aged from 0 to 16 years) and in 12 pre-pubertal GH deficient (GHD) children to study the correlation between the age and free IGF-1, total IGF-1 and IGFBP-3 levels. In healthy subjects (both sexes), serum free IGF-1, total IGF-1 and IGFBP-3 levels were low in infancy, increasing during puberty and declining thereafter. Free IGF-1 in serum occupied about 0.97-1.45 % of the total IGF-1 values, and the ratios of free IGF-1 to total IGF-1 were significantly increased in the pubertal age groups than in the pre-pubertal age groups. Serum levels of free IGF-1 showed significant positive correlation with those of total IGF-I and IGFBP-3. Serum free IGF-1, total IGF-1 and IGFBP-3 levels in patients with GHD were decreased significantly with increasing the degree of hypopituitarism. These observations suggest that the increase in serum free IGF-1 level during puberty was caused by a dramatic increase in total IGF-1 rather than IGFBP-3. Also, high levels of these hormones may play an important role in pubertal growth spurt and may become a useful tool for diagnosing GHD and predicting growth response to long term GH therapy

  15. Combined effect of electrode gap and radio frequency on power deposition and film growth kinetics in SiH4/H2 discharges

    International Nuclear Information System (INIS)

    Amanatides, E.; Mataras, D.; Rapakoulias, D.E.

    2002-01-01

    The combined effect of the variation of the interelectrode gap (1.3-2.5 cm) and radio frequency (13.56-50 MHz) on the properties of highly diluted silane in hydrogen discharges used for the deposition of microcrystalline silicon thin films is presented. The investigation included electrical and optical discharge measurements as well as the in situ determination of the film growth rate. In the lower frequencies regime, the increase of the interelectrode gap for the same applied voltage results in higher current flows and higher total power dissipation. On the other hand, at 50 MHz the variation of the interelectrode space has only a slight effect on the total power dissipation, due to the low excitation voltage. However, at all frequencies, the increase of the interelectrode space results in a drop of the power dissipation per discharge volume. This is related to the less effective energy transfer to the electrons that is due to the enhancement of the bulk relative to the sheath ohmic heating. The variation of the relative importance of the electron heating modes is reflected in the discharge radical production efficiency and the film growth rate

  16. Non-Epitaxial Thin-Film Indium Phosphide Photovoltaics: Growth, Devices, and Cost Analysis

    Science.gov (United States)

    Zheng, Maxwell S.

    In recent years, the photovoltaic market has grown significantly as module prices have continued to come down. Continued growth of the field requires higher efficiency modules at lower manufacturing costs. In particular, higher efficiencies reduce the area needed for a given power output, thus reducing the downstream balance of systems costs that scale with area such as mounting frames, installation, and soft costs. Cells and modules made from III-V materials have the highest demonstrated efficiencies to date but are not yet at the cost level of other thin film technologies, which has limited their large-scale deployment. There is a need for new materials growth, processing and fabrication techniques to address this major shortcoming of III-V semiconductors. Chapters 2 and 3 explore growth of InP on non-epitaxial Mo substrates by MOCVD and CSS, respectively. The results from these studies demonstrate that InP optoelectronic quality is maintained even by growth on non-epitaxial metal substrates. Structural characterization by SEM and XRD show stoichiometric InP can be grown in complete thin films on Mo. Photoluminescence measurements show peak energies and widths to be similar to those of reference wafers of similar doping concentrations. In chapter 4 the TF-VLS growth technique is introduced and cells fabricated from InP produced by this technique are characterized. The TF-VLS method results in lateral grain sizes of >500 mum and exhibits superior optoelectronic quality. First generation devices using a n-TiO2 window layer along with p-type TF-VLS grown InP have reached ˜12.1% power conversion efficiency under 1 sun illumination with VOC of 692 mV, JSC of 26.9 mA/cm2, and FF of 65%. The cells are fabricated using all non-epitaxial processing. Optical measurements show the InP in these cells have the potential to support a higher VOC of ˜795 mV, which can be achieved by improved device design. Chapter 5 describes a cost analysis of a manufacturing process using an

  17. AES study of growth process of al thin films on uranium dioxide

    International Nuclear Information System (INIS)

    Zhou Wei; Liu Kezhao; Yang Jiangrong; Xiao Hong

    2009-01-01

    Metallic uranium was exposed to 40 languirs of oxygen at room temperature in order to form UO 2 on the surface of metallic U. And thin layers of aluminum on UO 2 were prepared by sputter deposition under ultra high vacuum conditions. Process of Al thin film growth and its interaction with UO 2 were investigated by auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS). It was shown that the Al thin film growth underwent via the Volmer-Weber (VW) mode. At room temperature, Al and UO 2 interact with each other, electrons transfer occurres from Al atoms to uranium ions, and a few of Al 2 O 3 exist in the region of UO 2 /Al interface due to O 2 adsorption to the surface. Inter-diffusion between UO 2 and Al is observable. Aluminum diffuses into interface region of UO 2 and U. It results in the formation of a coexistence regime containing uranium oxide, metallic U and Al. (authors)

  18. Ion energy/momentum effects during ion assisted growth of niobium nitride films

    Science.gov (United States)

    Klingenberg, Melissa L.

    The research described herein was performed to better understand and discern ion energy vs. ion momentum effects during ion beam assisted (IBAD) film growth and their effects on residual stress, crystalline structure, morphology, and composition, which influence film tribological properties. NbxN y was chosen for this research because it is a refractory material that can possess a large number of crystalline structures, and it has been found to have good tribological properties. To separate the effects of momentum transfer per arriving atom (p/a), which considers bombarding species mass, energy, and ion-to-atom transport ratio, from those of energy deposition per arriving atom (E/a), a mass independent parameter, different inert ion beams (krypton, argon, and neon) were used to create a matrix of coatings formed using similar energy deposition, but different momentum transfer and vice versa. Deposition was conducted in a research-scale IBAD system using electron beam evaporation, a radio frequency ion source, and a neutral nitrogen gas backfill. Films were characterized using x-ray diffraction, atomic force microscopy, Rutherford backscattering spectrometry, and residual stress analysis. Direct and quantifiable effects of bombardment were observed; however, energy deposition and momentum transfer effects could not be completely separated, confirming that thin film processes are complex. Complexities arose from ion-specific interactions (ion size, recoil energy, per cent reflected neutrals, Penning ionization, etc.) and chemistry effects that are not considered by the simple models. Overall, it can be stated that bombardment promoted nitride formation, nanocrystallinity, and compressive stress formation; influenced morphology (which influenced post-deposition oxygen uptake) and stress evolution; increased lattice parameter; modified crystalline phase and texture; and led to inert gas incorporation. High stress levels correlated strongly with material disorder and

  19. Growth model and structure evolution of Ag layers deposited on Ge films.

    Science.gov (United States)

    Ciesielski, Arkadiusz; Skowronski, Lukasz; Górecka, Ewa; Kierdaszuk, Jakub; Szoplik, Tomasz

    2018-01-01

    We investigated the crystallinity and optical parameters of silver layers of 10-35 nm thickness as a function 2-10 nm thick Ge wetting films deposited on SiO 2 substrates. X-ray reflectometry (XRR) and X-ray diffraction (XRD) measurements proved that segregation of germanium into the surface of the silver film is a result of the gradient growth of silver crystals. The free energy of Ge atoms is reduced by their migration from boundaries of larger grains at the Ag/SiO 2 interface to boundaries of smaller grains near the Ag surface. Annealing at different temperatures and various durations allowed for a controlled distribution of crystal dimensions, thus influencing the segregation rate. Furthermore, using ellipsometric and optical transmission measurements we determined the time-dependent evolution of the film structure. If stored under ambient conditions for the first week after deposition, the changes in the transmission spectra are smaller than the measurement accuracy. Over the course of the following three weeks, the segregation-induced effects result in considerably modified transmission spectra. Two months after deposition, the slope of the silver layer density profile derived from the XRR spectra was found to be inverted due to the completed segregation process, and the optical transmission spectra increased uniformly due to the roughened surfaces, corrosion of silver and ongoing recrystallization. The Raman spectra of the Ge wetted Ag films were measured immediately after deposition and ten days later and demonstrated that the Ge atoms at the Ag grain boundaries form clusters of a few atoms where the Ge-Ge bonds are still present.

  20. Observation of feature ripening inversion effect at the percolation threshold for the growth of thin silver films

    Energy Technology Data Exchange (ETDEWEB)

    Nehm, Frederik, E-mail: frederik.nehm@iapp.de; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl

    2014-04-01

    The growth behavior of thin silver films on organic layers is investigated during deposition by means of simultaneous in-situ monitoring of sheet resistance and transmittance. Thermally evaporated films up to 11 nm show a distinct percolation behavior with strong resistance drop at the percolation thickness. Additionally, evaporations are divided into a sequence of one nanometer steps. In the deposition breaks, the films exhibit a ripening effect with an inversion at the percolation thickness, by changing from an increasing to decreasing sheet resistance over time. Scanning electron micrographs suggest same ripening mechanisms for islands below the percolation thickness as for holes above. - Highlights: • Fundamental understanding of metal thin film growth is presented. • Optical and electrical in-situ measurements used for optimizing transparent electrodes • Stepwise Ag deposition reveals extraordinary ripening effects. • Feature ripening inversion is discovered at the percolation threshold.

  1. Observation of feature ripening inversion effect at the percolation threshold for the growth of thin silver films

    International Nuclear Information System (INIS)

    Nehm, Frederik; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl

    2014-01-01

    The growth behavior of thin silver films on organic layers is investigated during deposition by means of simultaneous in-situ monitoring of sheet resistance and transmittance. Thermally evaporated films up to 11 nm show a distinct percolation behavior with strong resistance drop at the percolation thickness. Additionally, evaporations are divided into a sequence of one nanometer steps. In the deposition breaks, the films exhibit a ripening effect with an inversion at the percolation thickness, by changing from an increasing to decreasing sheet resistance over time. Scanning electron micrographs suggest same ripening mechanisms for islands below the percolation thickness as for holes above. - Highlights: • Fundamental understanding of metal thin film growth is presented. • Optical and electrical in-situ measurements used for optimizing transparent electrodes • Stepwise Ag deposition reveals extraordinary ripening effects. • Feature ripening inversion is discovered at the percolation threshold

  2. Mechanism of formation and growth of sunflower-shaped imperfections in anodic oxide films on niobium

    Energy Technology Data Exchange (ETDEWEB)

    Nagahara, K. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-ku, Sapporo 060-8628 (Japan); Sakairi, M. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-ku, Sapporo 060-8628 (Japan); Takahashi, H. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-ku, Sapporo 060-8628 (Japan)]. E-mail: Takahasi@elechem1-mc.eng.hokudai.ac.jp; Matsumoto, K. [Cabot Supermetals K.K., Higashinagahara Works, 111 Nagayachi, Kawahigashi-machi, Kawanuma-gun, Fukushima-ken 969-3431 (Japan); Takayama, K. [Cabot Supermetals K.K., Higashinagahara Works, 111 Nagayachi, Kawahigashi-machi, Kawanuma-gun, Fukushima-ken 969-3431 (Japan); Oda, Y. [Cabot Supermetals K.K., Higashinagahara Works, 111 Nagayachi, Kawahigashi-machi, Kawanuma-gun, Fukushima-ken 969-3431 (Japan)

    2007-01-01

    Anodizing of niobium has been investigated to develop niobium solid electrolytic capacitors. Chemically polished niobium specimens were anodized in a diluted phosphoric acid solution, initially galvanostatically at i {sub a} = 4 A m{sup -2} up to E {sub a} = 100 V, and then potentiostatically at E {sub a} = 100 V for t {sub pa} = 43.2 ks. During the galvanostatic anodizing, the anode potential increased almost linearly with time, while, during potentiostatic anodizing, the anodic current decreased up to t {sub pa} = 3.6 ks, and then increased slowly before decreasing again after t {sub pa} = 30.0 ks. Images of FE-SEM and in situ AFM showed that nuclei of imperfections were formed at the ridge of cell structures before t {sub pa} = 3.6 ks. After formation, the imperfection nuclei grew, showing cracking and rolling-up of the anodic oxide film, and crystalline oxide was formed at the center of imperfections after t {sub pa} = 3.6 ks. The growth of imperfections caused increases in the anodic current between t {sub pa} = 3.6 and 30.0 ks. Long-term anodizing caused a coalescence of the imperfections, leading to decreases in the anodic current after t {sub pa} = 30.0 ks. As the imperfections grew, the dielectric dispersion of the anodic oxide films became serious, showing a bias voltage dependence of the parallel equivalent capacitance, C {sub p}, and a dielectric dissipation factor, tan {delta}. The mechanism of formation and growth of the imperfections, and the correlation between the structure and dielectric properties of anodic oxide films is discussed.

  3. Influence of lake surface area and total phosphorus on annual bluegill growth in small impoundments of central Georgia

    Science.gov (United States)

    Jennings, Cecil A.; Sundmark, Aaron P.

    2017-01-01

    The relationships between environmental variables and the growth rates of fishes are important and rapidly expanding topics in fisheries ecology. We used an informationtheoretic approach to evaluate the influence of lake surface area and total phosphorus on the age-specific growth rates of Lepomis macrochirus (Bluegill) in 6 small impoundments in central Georgia. We used model averaging to create composite models and determine the relative importance of the variables within each model. Results indicated that surface area was the most important factor in the models predicting growth of Bluegills aged 1–4 years; total phosphorus was also an important predictor for the same age-classes. These results suggest that managers can use water quality and lake morphometry variables to create predictive models specific to their waterbody or region to help develop lake-specific management plans that select for and optimize local-level habitat factors for enhancing Bluegill growth.

  4. A study of growth and thermal dewetting behavior of ultra-thin gold films using transmission electron microscopy

    Directory of Open Access Journals (Sweden)

    Sudheer

    2017-07-01

    Full Text Available The growth and solid-state dewetting behavior of Au thin films (0.7 to 8.4 nm deposited on the formvar film (substrate by sputtering technique have been studied using transmission electron microscopy. The size and number density of the Au nanoparticles (NPs change with an increase in the film thickness (0.7 to 2.8 nm. Nearly spherical Au NPs are obtained for 6 nm show capability to be used as an irreversible temperature sensor with a sensitivity of ∼0.1 CAF/°C. It is observed that annealing affects the crystallinity of the Au grains in the films. The electron diffraction measurement also shows annealing induced morphological evolution in the percolated Au thin films (≥3 nm during solid-state dewetting and recrystallization of the grains.

  5. Growth of TiC films by Pulsed Laser Evaporation (PLE) and characterization by XPS and AES

    International Nuclear Information System (INIS)

    Rist, O.; Murray, P.T.

    1991-01-01

    Thin films of TiC with a thickness of some 100 nm have been grown on Si(100) substrates by Pulsed Laser Evaporation (PLE). Advantages of PLE in comparison with more conventional growth methods e.g. PVD or CVD are reported. The feasibility of growing stoichiometric thin films of TiC by PLE was investigated. These films produced have been analysed in situ by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). XPS results and Auger sputter depht profiles indicate that the films grown between RT and 500degC are stoichiometric TiC. Film/substrate interdiffusion is observed at 600degC substrate temperature and higher. (orig.)

  6. NATO Advanced Research Workshop on Thin Film Growth Techniques for Low-Dimensional Structures

    CERN Document Server

    Parkin, S; Dobson, P; Neave, J; Arrott, A

    1987-01-01

    This work represents the account of a NATO Advanced Research Workshop on "Thin Film Growth Techniques for Low Dimensional Structures", held at the University of Sussex, Brighton, England from 15-19 Sept. 1986. The objective of the workshop was to review the problems of the growth and characterisation of thin semiconductor and metal layers. Recent advances in deposition techniques have made it possible to design new material which is based on ultra-thin layers and this is now posing challenges for scientists, technologists and engineers in the assessment and utilisation of such new material. Molecular beam epitaxy (MBE) has become well established as a method for growing thin single crystal layers of semiconductors. Until recently, MBE was confined to the growth of III-V compounds and alloys, but now it is being used for group IV semiconductors and II-VI compounds. Examples of such work are given in this volume. MBE has one major advantage over other crystal growth techniques in that the structure of the growi...

  7. Microstructure and initial growth characteristics of the low temperature microcrystalline silicon films on silicon nitride surface

    International Nuclear Information System (INIS)

    Park, Young-Bae; Rhee, Shi-Woo

    2001-01-01

    Microstructure and initial growth characteristics of the hydrogenated microcrystalline Si (μc-Si:H) films grown on hydrogenated amorphous silicon nitride (a-SiN x :H) surface at low temperature were investigated using high resolution transmission electron microscope and micro-Raman spectroscopy. With increasing the Si and Si - H contents in the SiN x :H surfaces, μc-Si crystallites, a few nanometers in size, were directly grown on amorphous nitride surfaces. It is believed that the crystallites were grown through the nucleation and phase transition from amorphous to crystal in a hydrogen-rich ambient of gas phase and growing surface. The crystallite growth characteristics on the dielectric surface were dependent on the stoichiometric (x=N/Si) ratio corresponding hydrogen bond configuration of the SiN x :H surface. Surface facetting and anisotropic growth of the Si crystallites resulted from the different growth rate on the different lattice planes of Si. No twins and stacking faults were observed in the (111) lattice planes of the Si crystallites surrounding the a-Si matrix. This atomic-scale structure was considered to be the characteristic of the low temperature crystallization of the μc-Si:H by the strain relaxation of crystallites in the a-Si:H matrix. [copyright] 2001 American Institute of Physics

  8. Heteroepitaxial growth of SiC films by carbonization of polyimide Langmuir-Blodgett films on Si

    Directory of Open Access Journals (Sweden)

    Goloudina S.I.

    2017-01-01

    Full Text Available High quality single crystal SiC films were prepared by carbonization of polyimide Langmuir-Blodgett films on Si substrate. The films formed after annealing of the polyimide films at 1000°C, 1100°C, 1200°C were studied by Fourier transform-infrared (FTIR spectroscopy, X-ray diffraction (XRD, Raman spectroscopy, transmission electon microscopy (TEM, transmission electron diffraction (TED, and scanning electron microscopy (SEM. XRD study and HRTEM cross-section revealed that the crystalline SiC film begins to grow on Si (111 substrate at 1000°C. According to the HRTEM cross-section image five planes in 3C-SiC (111 film are aligned with four Si(111 planes at the SiC/Si interface. It was shown the SiC films (35 nm grown on Si(111 at 1200°C have mainly cubic 3C-SiC structure with a little presence of hexagonal polytypes. Only 3C-SiC films (30 nm were formed on Si (100 substrate at the same temperature. It was shown the SiC films (30-35 nm are able to cover the voids in Si substrate with size up to 10 μm.

  9. Growth of tin oxide thin films composed of nanoparticles on hydrophilic and hydrophobic glass substrates by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Paloly, Abdul Rasheed; Satheesh, M. [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Martínez-Tomás, M. Carmen; Muñoz-Sanjosé, Vicente [Departamento de Física Aplicada y Electromagnetismo, Universitat de Valencia, c/Dr Moliner 50, Burjassot, Valencia 46100 (Spain); Rajappan Achary, Sreekumar [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Bushiri, M. Junaid, E-mail: junaidbushiri@gmail.com [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India)

    2015-12-01

    Highlights: • SnO{sub 2} thin films were grown on hydrophilic and hydrophobic glass substrates. • Samples on hydrophobic substrates are having comparatively larger lattice volume. • Films on hydrophobic substrates have larger particles and low density distribution. • Substrate dependent photoluminescence emission is observed and studied. • SnO{sub 2} thin films grown over hydrophobic substrates may find potential applications. - Abstract: In this paper, we have demonstrated the growth of tin oxide (SnO{sub 2}) thin films composed of nanoparticles on hydrophobic (siliconized) and hydrophilic (non-siliconized) glass substrates by using the spray pyrolysis technique. X-ray diffraction (XRD) analysis confirmed the formation of SnO{sub 2} thin films with tetragonal rutile-phase structure. Average particle size of nanoparticles was determined to be in the range of 3–4 nm measured from the front view images obtained by a field emission gun scanning electron microscope (FESEM), while the size of nanoparticle clusters, when present, were in the range of 11–20 nm. Surface morphology of SnO{sub 2} films grown over hydrophobic substrates revealed larger isolated particles which are less crowded compared to the highly crowded and agglomerated smaller particles in films on hydrophilic substrates. Blue shift in the band gap is observed in samples in which the average particle size is slightly larger than the exciton Bohr radius. Photoluminescence (PL) analysis of samples grown over hydrophobic substrates exhibited an intense defect level emission and a weak near band edge emission. The enhanced visible emission from these SnO{sub 2} thin films is attributed to lattice defects formed during the film growth due to the mismatch between the film and the hydrophobic substrate surface.

  10. Contribution to understanding and controlling a-Si:H thin films growth by mercury-sensitised photo-CVD

    International Nuclear Information System (INIS)

    Barhdadi, A.

    2003-09-01

    Mercury-sensitized photo-CVD technique is widely used for growing amorphous silicon thin films. This attractive method allows damage-free thin film depositions at very low substrate temperatures without the deleterious effects of the other processes. This review reports on the principle and potential of this technique. It also recalls and summarizes some fundamental issues such as experimental systems or apparatus particularities, the analysis of gas-phase reactions in the reactor, the surface-reaction model of SiH 3 and H during the film growth and all the kinetic model for lamp-induced Photo-CVD. (author)

  11. Epitaxial growth of cubic Gd{sub 2}O{sub 3} thin films on Ge substrates

    Energy Technology Data Exchange (ETDEWEB)

    Molle, A; Wiemer, C; Bhuiyan, M D N K; Tallarida, G; Fanciulli, M [CNR-INFM, Laboratorio Nazionale MDM, via C. Olivetti 2, I-20041 Agrate Brianza (Italy)], E-mail: alessandro.molle@mdm.infm.it

    2008-03-15

    Gd{sub 2}O{sub 3} thin films were grown on Ge (001) substrates by molecular beam epitaxy. The epitaxial character of the film is demonstrated by electron diffraction during the growth. The structural characterization of the films shows that the Gd{sub 2}O{sub 3} forms a bixbyite polymorph with a (110) out-of-plane orientation. The formation of bixbyite structured Gd{sub 2}O{sub 3} is discussed in terms of the atomic arrangement of the oxide planes on the Ge(001) surface.

  12. Epitaxial growth of manganese oxide films on MgAl2O4 (001) substrates and the possible mechanism

    Science.gov (United States)

    Ren, Lizhu; Wu, Shuxiang; Zhou, Wenqi; Li, Shuwei

    2014-03-01

    Three types of manganese oxide films were grown on MgAl2O4 (001) substrates by plasma-assisted molecular beam epitaxy (PA-MBE) under different growth rates and substrate temperatures. The structural characteristics and chemical compositions of the films were investigated by using in-situ reflection high-energy electron diffraction (RHEED), ex-situ X-ray diffraction, Raman, and X-ray photoelectron spectra (XPS). At a lower substrate temperature (730 K), the epitaxial film tends to form mixed phases with a coexistence of Mn3O4 and Mn5O8 in order to relieve the mismatch-strain. However, at a higher substrate temperature (750 K), all of the films crystallize into Mn3O4; the critical thickness of the film grown under a lower growth rate (7 Å/min) is much larger than that under a high growth rate (10 Å/min). When the film reaches a certain critical thickness, the surface will become fairly rough, and another oriented phase Mn3O4 would crystallize on such a surface.

  13. Improved interface growth and enhanced flux pinning in YBCO films deposited on an advanced IBAD-MgO based template

    Science.gov (United States)

    Khan, M. Z.; Zhao, Y.; Wu, X.; Malmivirta, M.; Huhtinen, H.; Paturi, P.

    2018-02-01

    The growth mechanism is studied from the flux pinning point of view in small-scale YBa2Cu3O6+x (YBCO) thin films deposited on a polycrystalline hastelloy with advanced IBAD-MgO based buffer layer architecture. When compared the situation with YBCO films grown on single crystal substrates, the most critical issues that affect the suitable defect formation and thus the optimal vortex pinning landscape, have been studied as a function of the growth temperature and the film thickness evolution. We can conclude that the best critical current property in a wide applied magnetic field range is observed in films grown at relatively low temperature and having intermediate thickness. These phenomena are linked to the combination of the improved interface growth, to the film thickness related crystalline relaxation and to the formation of linear array of edge dislocations that forms the low-angle grain boundaries through the entire film thickness and thus improve the vortex pinning properties. Hence, the optimized buffer layer structure proved to be particularly suitable for new coated conductor solutions.

  14. Growth and characteristics of PbS/polyvinyl alcohol nanocomposites for flexible high dielectric thin film applications

    International Nuclear Information System (INIS)

    Hmar, J.J.L.; Majumder, T.; Mondal, S.P.

    2016-01-01

    PbS/polyvinyl alcohol (PbS/PVA) nanocomposites have been grown by a chemical bath deposition process at various growth temperatures (60–100 °C). Transmission electron microscopy (TEM) study revealed the formation of PbS nanoparticles of diameter 6–20 nm encapsulated in PVA matrix. Optical band gap of the nanocomposite films have been found to decrease (1.45 eV–0.67 eV) with increase in growth temperature from 60 °C to 100 °C. The impedance measurements have been carried out by depositing the PbS/PVA films on indium tin oxide (ITO) coated flexible polyethylene terephthalate (PET) substrates. The room temperature dielectric permittivity and ac conductivity measurements have been carried out for ITO/PbS/PVA/Al devices deposited at various growth temperatures. The nanocomposite films demonstrate superior dielectric permittivity compare to pure PVA polymer. The flexibility studies of ITO/PbS/PVA/Al devices have been performed at different bending angles. - Highlights: • PbS nanoparticles of diameter 6–20 nm were grown in polyvinyl (PVA) matrix. • Optical band gap of nanocomposite films was varied from 1.45–0.67 eV. • The nanocomposite thin films demonstrated superior dielectric permittivity. • Flexibility study of thin film devices was performed at various bending angles.

  15. Texture of the nano-crystalline AlN thin films and the growth conditions in DC magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Shakil Khan

    2015-08-01

    Full Text Available DC reactive magnetron sputtering technique has been used for the preparation of AlN thin films. The deposition temperature and the flow ratio of N2/Ar were varied and subsequent dependency of the films crystallites orientation/texture has been addressed. In general, deposited films were found hexagonal polycrystalline with a (002 preferred orientation. The X-ray diffraction (XRD data revealed that the film crystallinity improves, with the increase of substrate temperature from 300 °C to 500 °C. The dropped in full width half maximum (FWHM of the XRD rocking curve value further confirmed it. However, increasing substrate temperature above 500 °C or reducing the nitrogen condition (from 60 to 30% in the environment induced the growth of crystallites with (102 and (103 orientations. The rise of rocking curve FWHM for the corresponding conditions depicted that the films texture quality deteriorated. A further confirmation of the variation in film texture/orentation with the growth conditions has been obtained from the variation in FWHM values of a dominant E1 (TO mode in the Fourier transform infrared (FTIR spectra and the E2 (high mode in Raman spectra. We have correlated the columnar structure in AFM surface analyses with the (002 or c-axis orientation as well. Spectroscopic ellipsometry of the samples have shown a higher refractive index at 500 °C growth temperature.

  16. The growth of GaN films by alternate source gas supply hot-mesh CVD method

    Energy Technology Data Exchange (ETDEWEB)

    Komae, Yasuaki; Saitou, Takeshi [Nagaoka University of Technology, Nagaoka 940-2188 (Japan); Suemitsu, Maki; Ito, Takashi [Center of Interdisciplinary Research, Tohoku University, Sendai 980-8578 (Japan); Endoh, Tetsuo [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Nakazawa, Hideki [Faculty of Science and Technology, Hirosaki University, Hirosaki 036-8561 (Japan); Narita, Yuzuru [Faculty of Engineering, Yamagata University, Yonezawa 992-8510 (Japan); Takata, Masasuke; Akahane, Tadashi [Nagaoka University of Technology, Nagaoka 940-2188 (Japan); Yasui, Kanji, E-mail: kyasui@vos.nagaokaut.ac.j [Nagaoka University of Technology, Nagaoka 940-2188 (Japan)

    2009-04-30

    Gallium nitride (GaN) films and Aluminium nitride (AlN) layers were deposited on SiC/Si (111) substrates by an alternating source gas supply or an intermittent supply of a source gas such as ammonia (NH{sub 3}), trimethylgallium (TMG) or trimethylaluminum (TMA) in a hot-mesh chemical vapor deposition (CVD) apparatus. The AlN layer was deposited as a buffer layer using NH{sub 3} and TMA on a SiC layer grown by carbonization on Si substrates using propane (C{sub 3}H{sub 8}). GaN films were grown on an AlN layer by a reaction between NH{sub x} radicals generated on a ruthenium (Ru) coated tungsten (W)-mesh and TMG molecules. An alternating source gas supply or an intermittent supply of one of the source gases during the film growth are expected to be effective for the suppression of gas phase reactions and for the enhancement of precursor migration on the substrate surface. By the intermittent supply of alkylmetal gas only during the growth of the AlN layer, the defect generation in the GaN films was reduced. GaN film growth by intermittent supply on an AlN buffer layer, however, did not lead to the improvement of the film quality.

  17. Research and development of photovoltaic power system. Study on growth mechanism of a-Si:H and preparation of the stable, high quality films; Taiyoko hatsuden system no kenkyu kaihatsu. Amorphous silicon no seimaku kiko to kohinshitsuka

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, M [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

    1994-12-01

    This paper reports the result obtained during fiscal 1994 on research on a film forming mechanism for amorphous silicon for solar cells and its quality improvement. In in-situ observation on plasma CVD surface reaction by using the total reflection infrared absorbing spectroscopy, an observation on a real time basis was performed on the reaction process of an a-Si:H surface in contact with gas mixture plasma composed of SiH4 + CH4. In microscopic observation on initial processes of amorphous silicon growth, surface morphological change before and after a-Si:H deposition at 200{degree}C was observed by using an inter-atomic force microscope. The observation verified that a-Si:H has grown to an atomic layer. In research on defect density in a-Si:H fabricated under high-speed film forming conditions, analysis was made on correlation between the film forming speed at 250{degree}C and defect density in the film. Other research works include those on a high-quality a-SiGe:H film fabricated by using the nanometer film forming/hydrogen plasma annealing method, modulated doping into multi-layer films of a-Si:H/a-Ge:H, and thin film transistor using very thin multi layer films of a-Si:H/a-Ge:H. 5 refs., 12 figs.

  18. Growth Related Carrier Mobility Enhancement of Pentacene Thin-Film Transistors with High-k Oxide Gate Dielectric

    International Nuclear Information System (INIS)

    Ai-Fang, Yu; Qiong, Qi; Peng, Jiang; Chao, Jiang

    2009-01-01

    Carrier mobility enhancement from 0.09 to 0.59 cm 2 /Vs is achieved for pentacene-based thin-film transistors (TFTs) by modifying the HfO 2 gate dielectric with a polystyrene (PS) thin film. The improvement of the transistor's performance is found to be strongly related to the initial film morphologies of pentacene on the dielectrics. In contrast to the three-dimensional island-like growth mode on the HfO 2 surface, the Stranski-Krastanov growth mode on the smooth and nonpolar PS/HfO 2 surface is believed to be the origin of the excellent carrier mobility of the TFTs. A large well-connected first monolayer with fewer boundaries is formed via the Stranski–Krastanov growth mode, which facilitates a charge transport parallel to the substrate and promotes higher carrier mobility. (cross-disciplinary physics and related areas of science and technology)

  19. Growth of epitaxial Pt thin films on (0 0 1) SrTiO{sub 3} by rf magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kahsay, A. [Departament de Física Aplicada i Òptica, Universitat de Barcelona, 08028 Barcelona (Spain); Polo, M.C., E-mail: mcpolo@ub.edu [Departament de Física Aplicada i Òptica, Universitat de Barcelona, 08028 Barcelona (Spain); Ferrater, C.; Ventura, J. [Departament de Física Aplicada i Òptica, Universitat de Barcelona, 08028 Barcelona (Spain); Rebled, J.M. [Departament d’Electrònica, Universitat de Barcelona Institut de Nanociència i Nanotecnologia IN 2UB, 08028 Barcelona (Spain); Varela, M. [Departament de Física Aplicada i Òptica, Universitat de Barcelona, 08028 Barcelona (Spain)

    2014-07-01

    The growth of platinum thin film by rf magnetron sputtering on SrTiO{sub 3}(0 0 1) substrates for oxide based devices was investigated. Platinum films grown at temperatures higher than 750 °C were epitaxial ([1 0 0]Pt(0 0 1)//[1 0 0]STO(0 0 1)), whereas at lower temperatures Pt(1 1 1) films were obtained. The surface morphology of the Pt films showed a strong dependence on the deposition temperature as was revealed by atomic force microscopy (AFM). At elevated temperatures there is a three-dimensional (3D) growth of rectangular atomically flat islands with deep boundaries between them. On the other hand, at low deposition temperatures, a two-dimensional (2D) layered growth was observed. The transition from 2D to 3D growth modes was observed that occurs for temperatures around 450 °C. The obtained epitaxial thin films also formed an atomically sharp interface with the SrTiO{sub 3}(0 0 1) substrate as confirmed by HRTEM.

  20. Structure and wettability property of the growth and nucleation surfaces of thermally treated freestanding CVD diamond films

    Science.gov (United States)

    Pei, Xiaoqiang; Cheng, Shaoheng; Ma, Yibo; Wu, Danfeng; Liu, Junsong; Wang, Qiliang; Yang, Yizhou; Li, Hongdong

    2015-08-01

    This paper reports the surface features and wettability properties of the (1 0 0)-textured freestanding chemical vapor deposited (CVD) diamond films after thermal exposure in air at high temperature. Thermal oxidation at proper conditions eliminates selectively nanodiamonds and non-diamond carbons in the films. The growth side of the films contains (1 0 0)-oriented micrometer-sized columns, while its nucleation side is formed of nano-sized tips. The examined wettability properties of the as-treated diamond films reveal a hydrophilicity and superhydrophilicity on the growth surface and nucleation surface, respectively, which is determined by oxygen termination and geometry structure of the surface. When the surface termination is hydrogenated, the wettability of nucleation side converted from superhydrophilicity to high hydrophobicity, while the hydrophilicity of the growth side does not change significantly. The findings open a possibility for realizing freestanding diamond films having not only novel surface structures but also multifunction applications, especially proposed on the selected growth side or nucleation side in one product.

  1. Shaping thin film growth and microstructure pathways via plasma and deposition energy: a detailed theoretical, computational and experimental analysis.

    Science.gov (United States)

    Sahu, Bibhuti Bhusan; Han, Jeon Geon; Kersten, Holger

    2017-02-15

    Understanding the science and engineering of thin films using plasma assisted deposition methods with controlled growth and microstructure is a key issue in modern nanotechnology, impacting both fundamental research and technological applications. Different plasma parameters like electrons, ions, radical species and neutrals play a critical role in nucleation and growth and the corresponding film microstructure as well as plasma-induced surface chemistry. The film microstructure is also closely associated with deposition energy which is controlled by electrons, ions, radical species and activated neutrals. The integrated studies on the fundamental physical properties that govern the plasmas seek to determine their structure and modification capabilities under specific experimental conditions. There is a requirement for identification, determination, and quantification of the surface activity of the species in the plasma. Here, we report a detailed study of hydrogenated amorphous and crystalline silicon (c-Si:H) processes to investigate the evolution of plasma parameters using a theoretical model. The deposition processes undertaken using a plasma enhanced chemical vapor deposition method are characterized by a reactive mixture of hydrogen and silane. Later, various contributions of energy fluxes on the substrate are considered and modeled to investigate their role in the growth of the microstructure of the deposited film. Numerous plasma diagnostic tools are used to compare the experimental data with the theoretical results. The film growth and microstructure are evaluated in light of deposition energy flux under different operating conditions.

  2. Supercritical CO2 impregnation of PLA/PCL films with natural substances for bacterial growth control in food packaging.

    Science.gov (United States)

    Milovanovic, Stoja; Hollermann, Gesa; Errenst, Cornelia; Pajnik, Jelena; Frerich, Sulamith; Kroll, Stephen; Rezwan, Kurosch; Ivanovic, Jasna

    2018-05-01

    Biodegradable polymers with antibacterial properties are highly desirable materials for active food packaging applications. Thymol, a dietary monoterpene phenol with a strong antibacterial activity is abundant in plants belonging to the genus Thymus. This study presents two approaches for supercritical CO 2 impregnation of poly(lactic acid)(PLA)/poly(ε-caprolactone)(PCL) blended films to induce antibacterial properties of the material: (i) a batch impregnation process for loading pure thymol, and (ii) an integrated supercritical extraction-impregnation process for isolation of thyme extract and its incorporation into the films, operated in both batch or semi-continuous modes with supercritical solution circulation. The PCL content in films, impregnation time and CO 2 flow regime were varied to maximize loading of the films with thymol or thyme extract with preserving films' structure and thermal stability. Representative film samples impregnated with thymol and thyme extract were tested against Gram (-) (Escherichia coli) and Gram(+) (Bacillus subtilis) model strains, by measuring their metabolic activity and re-cultivation after exposure to the films. The film containing thymol (35.8 wt%) showed a strong antibacterial activity leading to a total reduction of bacterial cell viability. Proposed processes enable fast, controlled and organic solvent-free fabrication of the PLA/PCL films containing natural antibacterial substances at moderately low temperature, with a compact structure and a good thermal stability, for potential use as active food packaging materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Serum levels of free and total insulin-link growth factor (IGF)-1 and (IGF) binding protein-3 in normal and growth hormone deficient children

    International Nuclear Information System (INIS)

    Shousha, M.A.; Soliman, S.E.T.; Hafez, H.M.

    2008-01-01

    Serum levels of total insulin-like growth factor- 1 (IGF-1) and IGF-binding protein-3 (IGFBP-3) reflect endogenous GH secretion in healthy children, which makes them good diagnostic markers for screening GH deficiency (GHD) in short children, although some controversy still exists. Only a minor fraction of the total IGF-1 circulates in its free form, which is believed to be the biologically active form. Serum levels of free IGF-1, total IGF-I and IGFBP-3 were measured in 144 healthy children (72 boys and 72 girls, aged from 0 to 16 years) and in 12 prepubertal GH. deficient (GHD) children to study correlation between the age and free IGF-1, total IGF-1 and IGFBP-3 levels. In healthy subjects (both sexes), serum free IGF-1, total IGF-1 and IGFBP-3 levels were low in infancy, increasing during puberty and declining thereafter. Free IGF-1 in serum occupied about 0.97. 1.45 % of the total IGF-1 values, and the ratios of free IGF-1 to total IGF-1 were significantly increased in the pubertal age groups than in the prepubertal age groups. Serum levels of free IGF-1 showed significant positive correlation with those of total IGF-I and IGFBP-3. Serum free IGF-1, total IGF-1 and IGFBP-3 levels in patients with GHD decreased significantly with increasing degree of hypopituitarism. These observations suggest that the increase in serum free IGF-1 level during puberty was caused by a dramatic increase in total IGF-1 rather than IGFBP-3. Also, high levels of these hormones may play an important role in pubertal growth spurt and may become a useful tool for diagnosing GHD and predicting growth response to long term GH therapy

  4. Optical monitoring of surface processes relevant to thin film growth by chemical vapour deposition

    International Nuclear Information System (INIS)

    Simcock, Michael Neil

    2002-01-01

    This thesis reports on the investigation of the use of reflectance anisotropy spectroscopy (RAS) as an in-situ monitor for the preparation and oxidation of GaAs(100) c(4x4) surfaces using a CVD 2000 MOCVD reactor. These surfaces were oxidised using air. It was found that it was possible to follow surface degradation using RA transients at 2.6eV and 4eV. From this data it was possible to speculate on the nature of the surface oxidation process. A study was performed into the rate of surface degradation under different concentrations of air, it was found that the relation between the air concentration and the surface degradation was complicated but that the behaviour of the first third of the degradation approximated a first order behaviour. An estimation of the activation energy of the process was then made, and an assessment of the potential use of the glove-box for STM studies which is an integral part of the MOCVD equipment was also made. Following this, a description is given of the construction of an interferometer for monitoring thin film growth. An investigation is also described into two techniques designed to evaluate the changes in reflected intensity as measured by an interferometer. The first technique uses an iteration procedure to determine the film thickness from the reflection data. This is done using a Taylor series expansion of the thin film reflection function to iterate for the thickness. Problems were found with the iteration when applied to noisy data, these were solved by using a least squares fit to smooth the data. Problems were also found with the iteration at the turning points these were solved using the derivative of the function and by anticipating the position of the turning points. The second procedure uses the virtual interface method to determine the optical constants of the topmost deposited material, the virtual substrate, and the growth rate. This method is applied by using a Taylor series expansion of the thin film reflection

  5. Growth, structure and magnetic properties of magnetron sputtered FePt thin films

    Energy Technology Data Exchange (ETDEWEB)

    Cantelli, Valentina

    2010-07-01

    The L1{sub 0} FePt phase belongs to the most promising hard ferromagnetic materials for high density recording media. The main challenges for thin FePt films are: (i) to lower the process temperature for the transition from the soft magnetic A1 to the hard magnetic L1{sub 0} phase, (ii) to realize c-axes preferential oriented layers independently from the substrate nature and (iii) to control layer morphology supporting the formation of FePt-L1{sub 0} selforganized isolated nanoislands towards an increase of the signal-to-noise ratio. In this study, dc magnetron sputtered FePt thin films on amorphous substrates were investigated. The work is focused on the correlation between structural and magnetic properties with respect to the influence of deposition parameters like growth mode (cosputtering vs. layer - by - layer) and the variation of the deposition gas (Ar, Xe) or pressure (0.3-3 Pa). In low-pressure Ar discharges, high energetic particle impacts support vacancies formation during layer growth lowering the phase transition temperature to (320{+-}20) C. By reducing the particle kinetic energy in Xe discharges, highly (001) preferential oriented L1{sub 0}-FePt films were obtained on a-SiO{sub 2} after vacuum annealing. L1{sub 0}-FePt nano-island formation was supported by the introduction of an Ag matrix, or by random ballistic aggregation and atomic self shadowing realized by FePt depositions at very high pressure (3 Pa). The high coercivity (1.5 T) of granular, magnetic isotropic FePt layers, deposited in Ar discharges, was measured with SQUID magnetometer hysteresis loops. For non-granular films with (001) preferential orientation the coercivity decreased (0.6 T) together with an enhancement of the out-of- plane anisotropy. Nanoislands show a coercive field close to the values obtained for granular layers but exhibit an in-plane easy axis due to shape anisotropy effects. An extensive study with different synchrotron X-ray scattering techniques, mainly

  6. Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition

    Directory of Open Access Journals (Sweden)

    Gene Siegel

    2015-05-01

    Full Text Available We are reporting the growth of single layer and few-layer MoS2 films on single crystal sapphire substrates using a pulsed-laser deposition technique. A pulsed KrF excimer laser (wavelength: 248 nm; pulse width: 25 ns was used to ablate a polycrystalline MoS2 target. The material thus ablated was deposited on a single crystal sapphire (0001 substrate kept at 700 °C in an ambient vacuum of 10−6 Torr. Detailed characterization of the films was performed using atomic force microscopy (AFM, Raman spectroscopy, UV-Vis spectroscopy, and photoluminescence (PL measurements. The ablation of the MoS2 target by 50 laser pulses (energy density: 1.5 J/cm2 was found to result in the formation of a monolayer of MoS2 as shown by AFM results. In the Raman spectrum, A1g and E12g peaks were observed at 404.6 cm−1 and 384.5 cm−1 with a spacing of 20.1 cm−1, confirming the monolayer thickness of the film. The UV-Vis absorption spectrum exhibited two exciton absorption bands at 672 nm (1.85 eV and 615 nm (2.02 eV, with an energy split of 0.17 eV, which is in excellent agreement with the theoretically predicted value of 0.15 eV. The monolayer MoS2 exhibited a PL peak at 1.85 eV confirming the direct nature of the band-gap. By varying the number of laser pulses, bi-layer, tri-layer, and few-layer MoS2 films were prepared. It was found that as the number of monolayers (n in the MoS2 films increases, the spacing between the A1g and E12g Raman peaks (Δf increases following an empirical relation, Δ f = 26 . 45 − 15 . 42 1 + 1 . 44 n 0 . 9 cm − 1 .

  7. Influence of humidity on the growth characteristics and properties of chemical bath-deposited ZnS thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Cheng; Chao, Yen-Tai [Department of Mechatronics Engineering, National Changhua University of Education, Changhua 50007, Taiwan (China); Yao, Pin-Chuan, E-mail: pcyao@mail.dyu.edu.tw [Department of Materials Science and Engineering, Da-Yeh University, Dacun, Changhua 51591, Taiwan (China)

    2014-07-01

    In this study, the effect of humidity on the growth characteristics and properties of chemical bath-deposited ZnS thin films was systematically investigated. All deposition was conducted by an open CBD system under various relative humidity levels (RH) or by a hermetic CBD system as a comparison. It shows, for films deposited by an open system, the ambient humidity plays an important role in the quality of the resultant films. Damp environments lead to powdery films. Generally, all films prepared in this study using NH{sub 3} and hydrazine hydrate as the complexing agents were amorphous or poorly crystalline. For an open system, the [H{sup +}] from the dissolved carbon dioxide in the air competes with the ammonium ions in the bath solution. According to Le Châtelier's principle, more ammonia was consumed, which favors the free [Zn{sup +2}] in the solution, facilitating the homogeneous precipitation of Zn(OH){sub 2} and giving rise to a powdery film. The x-ray photoelectron spectrum shows, for an open system, the content of Zn–O compounds in the form of Zn(OH){sub 2} and ZnO, etc., is increased by the relative humidity of the environment. The visible transmittance is reduced by RH. The higher optical band gap of the as-deposited films could be attributed to the quantum confinement effects due to the small grain size of the polycrystalline ZnS films over the substrates.

  8. Robust, flexible, and bioadhesive free-standing films for the co-delivery of antibiotics and growth factors.

    Science.gov (United States)

    Chen, Dongdong; Wu, Mingda; Chen, Jie; Zhang, Chunqiu; Pan, Tiezheng; Zhang, Bing; Tian, Huayu; Chen, Xuesi; Sun, Junqi

    2014-11-25

    Free-standing polymer films that adhere strongly to tissue and can codeliver multiple therapeutic agents in a controlled manner are useful as medical plasters. In this study, a bilayer polymer film comprising a drug reservoir layer and a supporting layer is fabricated by spin-coating poly(lactic-co-glycolic acid) (PLGA) on top of a layer-by-layer assembled film of poly(β-amino esters) (PAE), alginate sodium (ALG), and recombinant human basic fibroblast growth factor (bFGF). Apart from bFGF, the bilayer film can also load antibiotic drug ceftriaxone sodium (CTX) by a postdiffusion process. The PLGA supporting layer facilitates the direct peeling of the bilayer film from substrate to produce a robust and flexible free-standing film with excellent adhesion onto the human skin and porcine liver. The excellent adhesion of the bilayer film originates from the ALG component in the drug reservoir layer. CTX is quickly released by easily breaking its electrostatic interaction with the drug reservoir layer, whereas the sustained release of bFGF is due to the slow degradation of PAE component in the drug reservoir layer. Wounds can be synergetically treated by fast release of CTX to effectively eradicate invasive bacteria and by sustained release of bFGF to accelerate wound healing. Our results serve as a basis for designing multifunctional free-standing films with combination therapy for biomedical applications.

  9. Fetal and infant growth patterns associated with total and abdominal fat distribution in school-age children.

    Science.gov (United States)

    Gishti, Olta; Gaillard, Romy; Manniesing, Rashindra; Abrahamse-Berkeveld, Marieke; van der Beek, Eline M; Heppe, Denise H M; Steegers, Eric A P; Hofman, Albert; Duijts, Liesbeth; Durmuş, Büşra; Jaddoe, Vincent W V

    2014-07-01

    Higher infant growth rates are associated with an increased risk of obesity in later life. We examined the associations of longitudinally measured fetal and infant growth patterns with total and abdominal fat distribution in childhood. We performed a population-based prospective cohort study among 6464 children. We measured growth characteristics in the second and third trimesters of pregnancy, at birth, and at 6, 12, and 24 months. Body mass index, fat mass index (body fat mass/height(2)), lean mass index (body lean mass/height(2)), android/gynoid fat ratio measured by dual-energy x-ray absorptiometry, and sc and preperitoneal abdominal fat measured by ultrasound at the median age of 6.0 years (90% range, 5.7-7.4). We observed that weight gain in the second and third trimesters of fetal life and in early, mid, and late infancy were independently and positively associated with childhood body mass index (P fat mass index, android/gynoid fat ratio, and abdominal fat in childhood (P Children with both fetal and infant growth acceleration had the highest childhood body mass index, fat mass index, and sc abdominal fat, whereas children with fetal growth deceleration and infant growth acceleration had the highest value for android/gynoid fat ratio and the lowest value for lean mass index (P fat. Fetal growth deceleration followed by infant growth acceleration may lead to an adverse body fat distribution in childhood.

  10. Growth of Pb(Ti,Zr)O 3 thin films by metal-organic molecular beam epitaxy

    Science.gov (United States)

    Avrutin, V.; Liu, H. Y.; Izyumskaya, N.; Xiao, B.; Özgür, Ü.; Morkoç, H.

    2009-02-01

    Single-crystal Pb(Zr xTi 1-x)O 3 thin films have been grown on (0 0 1) SrTiO 3 and SrTiO 3:Nb substrates by molecular beam epitaxy using metal-organic source of Zr and two different sources of reactive oxygen—RF plasma and hydrogen-peroxide sources. The same growth modes and comparable structural properties were observed for the films grown with both oxygen sources, while the plasma source allowed higher growth rates. The films with x up to 0.4 were single phase, while attempts to increase x beyond gave rise to the ZrO 2 second phase. The effects of growth conditions on growth modes, Zr incorporation, and phase composition of the Pb(Zr xTi 1-x)O 3 films are discussed. Electrical and ferroelectric properties of the Pb(Zr xTi 1-x)O 3 films of ~100 nm in thickness grown on SrTiO 3:Nb were studied using current-voltage, capacitance-voltage, and polarization-field measurements. The single-phase films show low leakage currents and large breakdown fields, while the values of remanent polarization are low (around 5 μC/cm 2). It was found that, at high sweep fields, the contribution of the leakage current to the apparent values of remanent polarization can be large, even for the films with large electrical resistivity (˜10 8-10 9 Ω cm at an electric filed of 1 MV/cm). The measured dielectric constant ranges from 410 to 260 for Pb(Zr 0.33Ti 0.67)O 3 and from 313 to 213 for Pb(Zr 0.2Ti 0.8)O 3 in the frequency range from 100 to 1 MHz.

  11. Flow cytometry total cell counts : A field study assessing microbiological water quality and growth in unchlorinated drinking water distribution systems

    NARCIS (Netherlands)

    Liu, G.; Van der Mark, E.J.; Verberk, J.Q.; Van Dijk, J.C.

    2013-01-01

    e objective of this study was to evaluate the application of flow cytometry total cell counts (TCCs) as a parameter to assess microbial growth in drinking water distribution systems and to determine the relationships between different parameters describing the biostability of treated water. A

  12. Optimization of ion assist beam deposition of magnesium oxide template films during initial nucleation and growth

    Energy Technology Data Exchange (ETDEWEB)

    Groves, James R [Los Alamos National Laboratory; Matias, Vladimir [Los Alamos National Laboratory; Stan, Liliana [Los Alamos National Laboratory; De Paula, Raymond F [Los Alamos National Laboratory; Hammond, Robert H [STANFORD UNIV.; Clemens, Bruce M [STANFOED UNIV.

    2010-01-01

    Recent efforts in investigating the mechanism of ion beam assisted deposition (IBAD) of biaxially textured thin films of magnesium oxide (MgO) template layers have shown that the texture develops suddenly during the initial 2 nm of deposition. To help understand and tune the behavior during this initial stage, we pre-deposited thin layers of MgO with no ion assist prior to IBAD growth of MgO. We found that biaxial texture develops for pre-deposited thicknesses < 2 nm, and that the thinnest layer tested, at 1 nm, resulted in the best qualitative RHEED image, indicative of good biaxial texture development. The texture developed during IBAD growth on the 1.5 nm pre-deposited layer is slightly worse and IBAD growth on the 2 nm pre-deposited layer produces a fiber texture. Application of these layers on an Al{sub 2}O{sub 3} starting surface, which has been shown to impede texture development, improves the overall quality of the IBAD MgO and has some of the characteristics of a biaxially texture RHEED pattern. It is suggested that the use of thin (<2 nm) pre-deposited layers may eliminate the need for bed layers like Si{sub 3}N{sub 4} and Y{sub 2}O{sub 3} that are currently thought to be required for proper biaxial texture development in IBAD MgO.

  13. Modelling of epitaxial film growth with an Ehrlich-Schwoebel barrier dependent on the step height

    International Nuclear Information System (INIS)

    Leal, F F; Ferreira, S C; Ferreira, S O

    2011-01-01

    The formation of mounded surfaces in epitaxial growth is attributed to the presence of barriers against interlayer diffusion in the terrace edges, known as Ehrlich-Schwoebel (ES) barriers. We investigate a model for epitaxial growth using an ES barrier explicitly dependent on the step height. Our model has an intrinsic topological step barrier even in the absence of an explicit ES barrier. We show that mounded morphologies can be obtained even for a small barrier while a self-affine growth, consistent with the Villain-Lai-Das Sarma equation, is observed in the absence of an explicit step barrier. The mounded surfaces are described by a super-roughness dynamical scaling characterized by locally smooth (facetted) surfaces and a global roughness exponent α > 1. The thin film limit is featured by surfaces with self-assembled three-dimensional structures having an aspect ratio (height/width) that may increase or decrease with temperature depending on the strength of the step barrier. (fast track communication)

  14. Total Saponin from Root of Actinidia valvata Dunn Inhibits Hepatoma 22 Growth and Metastasis In Vivo by Suppression Angiogenesis

    Directory of Open Access Journals (Sweden)

    Guo-Yin Zheng

    2012-01-01

    Full Text Available The root of Actinidia valvata dunn has been widely used in the treatment of hepatocellular carcinoma (HCC, proved to be beneficial for a longer and better life in China. In present work, total saponin from root of Actinidia valvata Dunn (TSAVD was extracted, and its effects on hepatoma H22-based mouse in vivo were observed. Primarily transplanted hypodermal hepatoma H22-based mice were used to observe TSAVD effect on tumor growth. The microvessel density (MVD, vascular endothelial growth factor (VEGF, basic fibroblast growth factor (bFGF are characterized factors of angiogenesis, which were compared between TSAVD-treated and control groups. Antimetastasis effect on experimental pulmonary metastasis hepatoma mice was also observed in the study. The results demonstrated that TSAVD can effectively inhibit HCC growth and metastasis in vivo, inhibit the formation of microvessel, downregulate expressions of VEGF and bFGF, and retrain angiogenesis of hepatoma 22 which could be one of the reasons.

  15. Photoelectron diffraction study of Rh nanoparticles growth on Fe3O4/Pd(111) ultrathin film

    International Nuclear Information System (INIS)

    Abreu, G. J. P.; Pancotti, A; Lima, L. H. de; Landers, R.; Siervo, A. de

    2013-01-01

    Metallic nanoparticles (NPs) supported on oxides thin films are commonly used as model catalysts for studies of heterogeneous catalysis. Several 4d and 5d metal NPs (for example, Pd, Pt and Au) grown on alumina, ceria and titania have shown strong metal support interaction (SMSI), for instance the encapsulation of the NPs by the oxide. The SMSI plays an important role in catalysis and is very dependent on the support oxide used. The present work investigates the growth mechanism and atomic structure of Rh NPs supported on epitaxial magnetite Fe 3 O 4 (111) ultrathin films prepared on Pd(111) using the Molecular Beam Epitaxy (MBE) technique. The iron oxide and the Rh NPs were characterized using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction and photoelectron diffraction (PED). The combined XPS and PED results indicate that Rh NPs are metallic, cover approximately 20 % of the iron oxide surface and show height distribution ranging 3–5 ML (monolayers) with essentially a bulk fcc structure.

  16. Epitaxial growth of higher transition-temperature VO2 films on AlN/Si

    Directory of Open Access Journals (Sweden)

    Tetiana Slusar

    2016-02-01

    Full Text Available We report the epitaxial growth and the mechanism of a higher temperature insulator-to-metal-transition (IMT of vanadium dioxide (VO2 thin films synthesized on aluminum nitride (AlN/Si (111 substrates by a pulsed-laser-deposition method; the IMT temperature is TIMT ≈ 350 K. X-ray diffractometer and high resolution transmission electron microscope data show that the epitaxial relationship of VO2 and AlN is VO2 (010 ‖ AlN (0001 with VO2 [101] ‖   AlN   [ 2 1 ̄ 1 ̄ 0 ] zone axes, which results in a substrate-induced tensile strain along the in-plane a and c axes of the insulating monoclinic VO2. This strain stabilizes the insulating phase of VO2 and raises TIMT for 10 K higher than TIMT single crystal ≈ 340 K in a bulk VO2 single crystal. Near TIMT, a resistance change of about four orders is observed in a thick film of ∼130 nm. The VO2/AlN/Si heterostructures are promising for the development of integrated IMT-Si technology, including thermal switchers, transistors, and other applications.

  17. Nucleation and growth of a BCC Fe phase deposited on a single crystal (001) Cu film

    International Nuclear Information System (INIS)

    Koike, J.

    1991-01-01

    As a thin film overlayer grows on a substrate with a different structure, the overlayer initially adopts the substrate structure and subsequently transforms to an equilibrium bulk structure. such a growth characteristic has been extensively studied in Fe/Cu bicrystals. An Fe overlayer grown on a Cu substrate is known to have the fcc structure up to a thickness of 2 nm, whereas a thicker Fe overlayer consists of submicrometer grains of the bcc-Cu has been reported in a relatively thick Fe film and was found to consist of the Nishiyama (N), Kurdjumov-Sacks (KS), or Pitsch (P), depending on the orientation of the substrate surface. However, previous studies have not explained how the bcc structure nucleates or how the observed submicrometer polycrystalline grains form. The paper provides an understanding of these two points. Transmission electron microscopy (TEM) was used to study Fe/Cu bicrystals as the Fe thickness was varied systematically. Analysis of moire fringes, which are caused by superposition of different structures, enabled us to determine the orientation relationship between the very thin Fe layer and the Cu substrate. We show that a single variant of the P orientation relationship, which accompanies atomic rearrangement parallel to the interface, predominates at the nucleation stage of the bcc structure. Nucleation of other variants of P, N, and KS occurs with increasing Fe thickness and causes the formation of the submicrometer bcc grains

  18. Low Temperature Hydrothermal Growth of ZnO Nanorod Films for Schottky Diode Application

    International Nuclear Information System (INIS)

    Singh, Shaivalini; Park, Si-Hyun

    2016-01-01

    The purpose of this research is to report on the fabrication and characterizations of Pd/ZnO nanorod-based Schottky diodes for optoelectronic applications. ZnO nanorods (NRs) were grown on silicon (Si) substrates by a two step hydrothermal method. In the first step, a seed layer of pure ZnO was deposited from a solution of zinc acetate and ethyl alcohol, and then in the second step, the main growth of the ZnO NRs was done over the seed layer. The structural morphology and optical properties of the ZnO NR films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. The electrical characterization of the Pd/ZnO NR contacts was studied using a current-voltage (I-V) tool. The ZnO NR films exhibited a wurtzite ZnO structure,and the average length of the ZnO NRs were in the range of 750 nm to 800 nm. The values of ideality factor, turn-on voltage and reverse saturation current were calculated from the I-V characteristics of Pd/ZnO NR-based Schottky diodes. The study demonstrates that Pd/ZnO NR Schottky contacts fabricated by a simple and inexpensive method can be used as a substitute for conventional Schottky diodes for optoelectronic applications.

  19. Homo-epitaxial diamond film growth on ion implanted diamond substrates

    Energy Technology Data Exchange (ETDEWEB)

    Weiser, P.S.; Prawer, S.; Nugent, K.W.; Bettiol, A.A.; Kostidis, L.I.; Jamieson, D.N. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1996-12-31

    The nucleation of CVD diamond is a complicated process, governed by many interrelated parameters. In the present work we attempt to elucidate the effect of strain on the growth of a homo-epitaxial CVD diamond. We have employed laterally confined high dose (MeV) Helium ion implantation to produce surface swelling of the substrate. The strain is enhanced by the lateral confinement of the implanted region to squares of 100 x 100 {mu}m{sup 2}. After ion implantation, micro-Raman spectroscopy was employed to map the surface strain. The substrates were then inserted into a CVD reactor and a CVD diamond film was grown upon them. Since the strained regions were laterally confined, it was then possible to monitor the effect of strain on diamond nucleation. The substrates were also analysed using Rutherford Backscattering Spectroscopy (RBS), Proton induced X-ray Emission (PIXE) and Ion Beam induced Luminescence (IBIL). 7 refs., 5 figs.

  20. The growth of sodium rough films on mica (0001) as determined by Helium Atom Scattering

    DEFF Research Database (Denmark)

    Gerlach, Rolf; Balzer, Frank; Rubahn, Horst-Günter

    2001-01-01

    , which is addressed to Na atoms that fill cleavage-induced holes in the mica surface. It provides a convenient means of calibrating the coverage of the surface. With increasing surface coverage Na clusters are formed on the mica surface. A broad angular distribution of the scattered Helium intensity......Elastic helium atom scattering (HAS) and linear optical extinction measurements are used to investigate the growth of sodium (Na) films on mica substrates in the surface temperature range between 90 and 300 K. At half a monolayer (ML) surface coverage we observe a maximum of scattered He intensity...... is observed with a coverage-independent angular width above eight monolayers coverage. From simultaneous optical extinction measurements we deduce that the clusters are oblate with a ratio of semiaxes perpendicular and parallel to the surface plane between 0.23 and 0.165....

  1. Epitaxial growth and characterization of CoO/Fe(001) thin film layered structures

    International Nuclear Information System (INIS)

    Brambilla, A.; Sessi, P.; Cantoni, M.; Duo, L.; Finazzi, M.; Ciccacci, F.

    2008-01-01

    By means of X-ray photoemission spectroscopy and low energy electron diffraction, we show that it is possible to grow good quality thin epitaxial CoO films on Fe(001) substrates, through deposition in oxygen atmosphere. In particular, the composition and the structure of CoO(001)/Fe(001) bilayer systems and Fe(001)/CoO(001)/Fe(001) trilayer systems have been investigated by monitoring the evolution of the chemical interactions at the interfaces as a function of CoO thickness and growth temperature. We observe the presence of Fe oxides at the CoO/Fe interface and of a thin layer of metallic cobalt at the upper Fe/CoO interface of trilayer systems

  2. Homo-epitaxial diamond film growth on ion implanted diamond substrates

    Energy Technology Data Exchange (ETDEWEB)

    Weiser, P S; Prawer, S; Nugent, K W; Bettiol, A A; Kostidis, L I; Jamieson, D N [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1997-12-31

    The nucleation of CVD diamond is a complicated process, governed by many interrelated parameters. In the present work we attempt to elucidate the effect of strain on the growth of a homo-epitaxial CVD diamond. We have employed laterally confined high dose (MeV) Helium ion implantation to produce surface swelling of the substrate. The strain is enhanced by the lateral confinement of the implanted region to squares of 100 x 100 {mu}m{sup 2}. After ion implantation, micro-Raman spectroscopy was employed to map the surface strain. The substrates were then inserted into a CVD reactor and a CVD diamond film was grown upon them. Since the strained regions were laterally confined, it was then possible to monitor the effect of strain on diamond nucleation. The substrates were also analysed using Rutherford Backscattering Spectroscopy (RBS), Proton induced X-ray Emission (PIXE) and Ion Beam induced Luminescence (IBIL). 7 refs., 5 figs.

  3. Homo-epitaxial diamond film growth on ion implanted diamond substrates

    International Nuclear Information System (INIS)

    Weiser, P.S.; Prawer, S.; Nugent, K.W.; Bettiol, A.A.; Kostidis, L.I.; Jamieson, D.N.

    1996-01-01

    The nucleation of CVD diamond is a complicated process, governed by many interrelated parameters. In the present work we attempt to elucidate the effect of strain on the growth of a homo-epitaxial CVD diamond. We have employed laterally confined high dose (MeV) Helium ion implantation to produce surface swelling of the substrate. The strain is enhanced by the lateral confinement of the implanted region to squares of 100 x 100 μm 2 . After ion implantation, micro-Raman spectroscopy was employed to map the surface strain. The substrates were then inserted into a CVD reactor and a CVD diamond film was grown upon them. Since the strained regions were laterally confined, it was then possible to monitor the effect of strain on diamond nucleation. The substrates were also analysed using Rutherford Backscattering Spectroscopy (RBS), Proton induced X-ray Emission (PIXE) and Ion Beam induced Luminescence (IBIL). 7 refs., 5 figs

  4. Correlation of electrolyte-derived inclusions to crystallization in the early stage of anodic oxide film growth on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jaeggi, C., E-mail: christian.jaeggi@empa.ch [Empa, Swiss Federal Laboratories for Materials Testing and Research, Advanced Materials Processing Laboratory, Feuerwerkerstrasse 39, CH-3602 Thun (Switzerland); Parlinska-Wojtan, M., E-mail: magdalena.parlinska@empa.ch [Empa, Swiss Federal Laboratories for Materials Testing and Research, Center for Electron Microscopy, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Kern, P., E-mail: Philippe.Kern@neopac.ch [Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstrasse 39, CH-3602 Thun (Switzerland)

    2012-01-01

    Pure titanium has been subjected to anodization in sulfuric and phosphoric acid. For a better understanding of the oxide growth and properties of the final film, with a particular interest focused on the solution anions in the early stage of crystallization, microstructural analyses (Raman, Transmission Electron Microscopy [TEM]) of the oxide films were correlated to chemical depth profiling by glow discharge optical emission spectroscopy (GDOES). Raman spectroscopy shows that crystallization of the oxide films starts at potentials as low as 10-20 V. The onset of crystallization and the ongoing increase in crystallinity with increasing anodization potentials had already earlier been correlated to ac-impedance measurements [Jaeggi et al., Surf. Interface Anal. 38 (2006) 182]. TEM observations show a clear difference in the early phase of crystallization between oxides grown in 1 M sulfuric acid compared to 1 M phosphoric acid. Moreover, independent of electrolyte type, nano-sized pores from oxygen bubbles formation were revealed in the central part of the films. Until now, oxygen bubbles inside an anodically grown oxide have not been observed before without the presence of crystalline regions nearby. A growth model is proposed, in which the different starting locations of crystallization inside the films are correlated to the presence of the acid anions as residues in the film, as found by GDOES chemical depth-profiling.

  5. Optimization of conditions for growth of vanadium dioxide thin films on silicon by pulsed-laser deposition

    Science.gov (United States)

    Shibuya, Keisuke; Sawa, Akihito

    2015-10-01

    We systematically examined the effects of the substrate temperature (TS) and the oxygen pressure (PO2) on the structural and optical properties polycrystalline V O2 films grown directly on Si(100) substrates by pulsed-laser deposition. A rutile-type V O2 phase was formed at a TS ≥ 450 °C at PO2 values ranging from 5 to 20 mTorr, whereas other structures of vanadium oxides were stabilized at lower temperatures or higher oxygen pressures. The surface roughness of the V O2 films significantly increased at growth temperatures of 550 °C or more due to agglomeration of V O2 on the surface of the silicon substrate. An apparent change in the refractive index across the metal-insulator transition (MIT) temperature was observed in V O2 films grown at a TS of 450 °C or more. The difference in the refractive index at a wavelength of 1550 nm above and below the MIT temperature was influenced by both the TS and PO2, and was maximal for a V O2 film grown at 450 °C under 20 mTorr. Based on the results, we derived the PO2 versus 1/TS phase diagram for the films of vanadium oxides, which will provide a guide to optimizing the conditions for growth of V O2 films on silicon platforms.

  6. Optimization of conditions for growth of vanadium dioxide thin films on silicon by pulsed-laser deposition

    Directory of Open Access Journals (Sweden)

    Keisuke Shibuya

    2015-10-01

    Full Text Available We systematically examined the effects of the substrate temperature (TS and the oxygen pressure (PO2 on the structural and optical properties polycrystalline V O2 films grown directly on Si(100 substrates by pulsed-laser deposition. A rutile-type V O2 phase was formed at a TS ≥ 450 °C at PO2 values ranging from 5 to 20 mTorr, whereas other structures of vanadium oxides were stabilized at lower temperatures or higher oxygen pressures. The surface roughness of the V O2 films significantly increased at growth temperatures of 550 °C or more due to agglomeration of V O2 on the surface of the silicon substrate. An apparent change in the refractive index across the metal–insulator transition (MIT temperature was observed in V O2 films grown at a TS of 450 °C or more. The difference in the refractive index at a wavelength of 1550 nm above and below the MIT temperature was influenced by both the TS and PO2, and was maximal for a V O2 film grown at 450 °C under 20 mTorr. Based on the results, we derived the PO2 versus 1/TS phase diagram for the films of vanadium oxides, which will provide a guide to optimizing the conditions for growth of V O2 films on silicon platforms.

  7. Surface morphology study on chromium oxide growth on Cr films by Nd-YAG laser oxidation process

    International Nuclear Information System (INIS)

    Dong Qizhi; Hu Jiandong; Guo Zuoxing; Lian Jianshe; Chen Jiwei; Chen Bo

    2002-01-01

    Grain sized (60-100 nm) Cr 2 O 3 thin films were prepared on Cr thin film surfaces by Nd-YAG laser photothermal oxidation process. Surface morphology study showed crack-free short plateau-like oxide films formed. Increase of dislocation density after pulsed laser irradiation was found. Thin film external surfaces, grain boundaries and dislocations are main paths of laser surface oxidation. Pinning and sealing of grain boundary was the reason that deeper oxidation did not produce. Grain growth and agglomeration of Cr sub-layer yielded tensile stress on the surface Cr 2 O 3 thin film. It was the reason that short plateau-like surface morphology formed and cracks appeared sometimes. In oxygen annealing at 700 deg. C, grain boundaries were considered not to be pinned at the surface, mixture diffusion was main mechanism in growth of oxide. Compression stress development in whole film led to extrusion of grains that was the reason that multiple appearances such as pyramid-like and nutshell-like morphology formed

  8. Growth Assisted by Glancing Angle Deposition: A New Technique to Fabricate Highly Porous Anisotropic Thin Films.

    Science.gov (United States)

    Sanchez-Valencia, Juan Ramon; Longtin, Remi; Rossell, Marta D; Gröning, Pierangelo

    2016-04-06

    We report a new methodology based on glancing angle deposition (GLAD) of an organic molecule in combination with perpendicular growth of a second inorganic material. The resulting thin films retain a very well-defined tilted columnar microstructure characteristic of GLAD with the inorganic material embedded inside the columns. We refer to this new methodology as growth assisted by glancing angle deposition or GAGLAD, since the material of interest (here, the inorganic) grows in the form of tilted columns, though it is deposited under a nonglancing configuration. As a "proof of concept", we have used silver and zinc oxide as the perpendicularly deposited material since they usually form ill-defined columnar microstructures at room temperature by GLAD. By means of our GAGLAD methodology, the typical tilted columnar microstructure can be developed for materials that otherwise do not form ordered structures under conventional GLAD. This simple methodology broadens significantly the range of materials where control of the microstructure can be achieved by tuning the geometrical deposition parameters. The two examples presented here, Ag/Alq3 and ZnO/Alq3, have been deposited by physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD), respectively: two different vacuum techniques that illustrate the generality of the proposed technique. The two type of hybrid samples present very interesting properties that demonstrate the potentiality of GAGLAD. On one hand, the Ag/Alq3 samples present highly optical anisotropic properties when they are analyzed with linearly polarized light. To our knowledge, these Ag/Alq3 samples present the highest angular selectivity reported in the visible range. On the other hand, ZnO/Alq3 samples are used to develop highly porous ZnO thin films by using Alq3 as sacrificial material. In this way, antireflective ZnO samples with very low refractive index and extinction coefficient have been obtained.

  9. Crystallography and Growth of Epitaxial Oxide Films for Fundamental Studies of Cathode Materials Used in Advanced Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Leonid A. Bendersky

    2017-05-01

    Full Text Available Li-ion battery systems, synthesized as epitaxial thin films, can provide powerful insights into their electrochemical processes. Crystallographic analysis shows that many important cathode oxides have an underlying similarity: their structures can be considered as different ordering schemes of Li and transition metal ions within a pseudo-cubic sublattice of oxygen anions arranged in a face-center cubic (FCC fashion. This oxygen sublattice is compatible with SrTiO3 and similar perovskite oxides, thus perovskites can be used as supporting substrates for growing epitaxial cathode films. The predicted epitaxial growth and crystallographic relations were experimentally verified for different oxide films deposited by pulsed laser deposition (PLD on SrTiO3 or SrRuO3/SrTiO3 of different orientations. The results based on cross-sectional high-resolution TEM of the following films are presented in the paper: (a trigonal LiCoO2; (b orthorhombic LiMnO2; (c monoclinic Li2MnO3; (d compositionally-complex monoclinic Li1.2Mn0.55Ni0.15Co0.1O2. All results demonstrated the feasibility of epitaxial growth for these materials, with the growth following the predicted cube-on-cube orientation relationship between the cubic and pseudo-cubic oxygen sublattices of a substrate and a film, respectively.

  10. Influence of substrate temperature, growth rate and TCO substrate on the properties of CSS deposited CdS thin films

    Energy Technology Data Exchange (ETDEWEB)

    Schaffner, J., E-mail: jschaffner@surface.tu-darmstadt.de; Feldmeier, E.; Swirschuk, A.; Schimper, H.-J.; Klein, A.; Jaegermann, W.

    2011-08-31

    The growth of CdS thin films by close space sublimation (CSS) has been systematically studied using an ultra-high vacuum system known as DAISY-SOL in order to understand the basic growth mechanisms and their impact on the film properties. Substrate temperature and deposition rate were varied, and the surface properties of the CdS layer were determined by photoelectron spectroscopy (XPS) without breaking the vacuum. To analyze the influence of the deposition conditions on the layer morphology and crystallographic structure, the films were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM and AFM studies show a correlation between the deposition rate and the film morphology. For high deposition rates, edged grain shapes and smoother surfaces were observed than for low deposition rates. CdS films were deposited onto two different commercially available fluorine-doped tin oxide (FTO) substrates. XRD studies show that a high <200> texture of the FTO substrate prefers the CdS growth in <0001> orientation of the hexagonal crystal modification.

  11. Growth of C60 thin films on Al2O3/NiAl(100) at early stages

    Science.gov (United States)

    Hsu, S.-C.; Liao, C.-H.; Hung, T.-C.; Wu, Y.-C.; Lai, Y.-L.; Hsu, Y.-J.; Luo, M.-F.

    2018-03-01

    The growth of thin films of C60 on Al2O3/NiAl(100) at the earliest stage was studied with scanning tunneling microscopy and synchrotron-based photoelectron spectroscopy under ultrahigh-vacuum conditions. C60 molecules, deposited from the vapor onto an ordered thin film of Al2O3/NiAl(100) at 300 K, nucleated into nanoscale rectangular islands, with their longer sides parallel to direction either [010] or [001] of NiAl. The particular island shape resulted because C60 diffused rapidly, and adsorbed and nucleated preferentially on the protrusion stripes of the crystalline Al2O3 surface. The monolayer C60 film exhibited linear protrusions of height 1-3 Å, due to either the structure of the underlying Al2O3 or the lattice mismatch at the boundaries of the coalescing C60 islands; such protrusions governed also the growth of the second layer. The second layer of the C60 film grew only for a C60 coverage >0.60 ML, implying a layer-by-layer growth mode, and also ripened in rectangular shapes. The thin film of C60 was thermally stable up to 400 K; above 500 K, the C60 islands dissociated and most C60 desorbed.

  12. Multiplex ready flow cytometric immunoassay for total insulin like growth factor 1 in serum of cattle

    NARCIS (Netherlands)

    Bremer, M.G.E.G.; Smits, N.G.E.; Haasnoot, W.; Nielen, M.W.F.

    2010-01-01

    The European Union has banned the use of recombinant bovine somatotropins (rbST, growth hormones) to increase milk yield in dairy cattle. As direct detection of rbST in serum is problematic, methods based on the detection of changes in multiple rbST-dependent biomarkers have high potential for

  13. Effect of road side dust pollution on the growth and total chlorophyll ...

    African Journals Online (AJOL)

    SAM

    2014-02-25

    Feb 25, 2014 ... activities and traffic congestion contributes most of air pollution problems, resulting in damage to the plants growth. Therefore, the present work was mainly designed to analyze the effects of air born-dust pollution, dom- nantly presented by automobile, industrial pollution and microclimate on physiology and ...

  14. Effects of Sb-doping on the grain growth of Cu(In, Ga)Se2 thin films fabricated by means of single-target sputtering

    International Nuclear Information System (INIS)

    Zhang, Shu; Wu, Lu; Yue, Ruoyu; Yan, Zongkai; Zhan, Haoran; Xiang, Yong

    2013-01-01

    To investigate the effects of Sb doping on the kinetics of grain growth in Cu(In,Ga)Se 2 (CIGS) thin films during annealing, CIGS thin films were sputtered onto Mo coated substrates from a single CIGS alloy target, followed by chemical bath deposition of Sb 2 S 3 thin layers on top of CIGS layers and subsequent annealing at different temperatures for 30 min in Se vapors. X-ray diffraction results showed that CIGS thin films were obtained directly using the single-target sputtering method. After annealing, the In/Ga ratio in Sb-doped CIGS thin films remained stable compared to undoped film, possibly because Sb can promote the incorporation of Ga into CIGS. The grain growth in CIGS thin films was enhanced after Sb doping, exhibiting significantly larger grains after annealing at 400 °C or 450 °C compared to films without Sb. In particular, the effect was strikingly significant in grain growth across the film thickness, resulting in columnar grain structure in Sb-doped films. This grain growth improvement may be led by the diffusion of Sb from the front surface to the CIGS-Mo back interface, which promoted the mass transport process in CIGS thin films. - Highlights: ► Cu(In,Ga)Se 2 (CIGS) thin films made by sputtering from a single CIGS target. ► Chemical bath deposition used to introduce antimony into CIGS absorber layers. ► In/Ga ratio decreases in Sb-doped annealed films, comparatively to undoped films. ► Sb-doped CIGS films are superior to undoped films in terms of grain-growth kinetics

  15. Metal-to-Insulator Transition in Anatase TiO2 Thin Films Induced by Growth Rate Modulation

    International Nuclear Information System (INIS)

    Tachikawa, Takashi

    2012-01-01

    We demonstrate control of the carrier density of single phase anatase TiO 2 thin films by nearly two orders of magnitude by modulating the growth kinetics during pulsed laser deposition, under fixed thermodynamic conditions. The resistivity and the intensity of the photoluminescence spectra of these TiO 2 samples, both of which correlate with the number of oxygen vacancies, are shown to depend strongly on the growth rate. A quantitative model is used to explain the carrier density changes.

  16. KMCThinFilm: A C++ Framework for the Rapid Development of Lattice Kinetic Monte Carlo (kMC) Simulations of Thin Film Growth

    Science.gov (United States)

    2015-09-01

    direction, so if the simulation domain is set to be a certain size, then that presents a hard ceiling on the thickness of a film that may be grown in...FFA, Los J, Cuppen HM, Bennema P, Meekes H. MONTY:  Monte Carlo crystal growth on any crystal structure in any crystallographic orientation...mhoffman.github.io/kmos/. 23. Kiravittaya S, Schmidt OG. Quantum-dot crystal defects. Applied Physics Letters. 2008;93:173109. 24. Leetmaa M

  17. Investigation of growth, structural and electronic properties of V2O3 thin films on selected substrates

    International Nuclear Information System (INIS)

    Nateprov, Alexei

    2006-08-01

    The present work is devoted to the experimental study of the MI transition in V 2 O 3 thin films, grown on different substrates. The main goal of the work was to develop a technology of growth of V 2 O 3 thin films on substrates with different electrical and structural properties (diamond and LiNbO 3 ), designed for specific applications. The structural and electrical properties of the obtained films were characterized in detail with a special focus on their potential applications. The MIT of V 2 O 3 was investigated by SAW using first directly deposited V 2 O 3 thin film onto a LiNbO 3 substrate. (orig.)

  18. Growth of Highly Epitaxial YBa2Cu3O7-δ Films from a Simple Propionate-Based Solution

    DEFF Research Database (Denmark)

    Yue, Zhao; Torres, Pol; Tang, Xiao

    2015-01-01

    Intensive investigations have been conducted to develop epitaxial oxide thin films with superior electromagnetic performance by low-cost chemical solution deposition routes. In this paper, a novel propionate-based precursor solution without involving any other additive was proposed and employed...... to grow superconducting YBa2Cu3O7-δ (YBCO) films on LaAlO3 (LAO) single crystals. The precursor solutions are stable with a long shelf life of up to several months. Since the primary compositions are propionates after evaporating the solvent, the toxic reagents and evolved gases during solution synthesis...... and heat treatment can be eliminated completely. In this process, rapid pyrolysis and high conversation rate can also be achieved during growth of YBCO films in comparison with the conventional trifluoroacetate metal organic deposition routes. Remarkably, a 210 nm YBCO film exhibits high superconducting...

  19. Growth and magnetic properties of multiferroic LaxBi1-xMnO3 thin films

    Science.gov (United States)

    Gajek, M.; Bibes, M.; Wyczisk, F.; Varela, M.; Fontcuberta, J.; Barthélémy, A.

    2007-05-01

    A comparative study of LaxBi1-xMnO3 thin films grown on SrTiO3 substrates is reported. It is shown that these films grow epitaxially in a narrow pressure-temperature range. A detailed structural and compositional characterization of the films is performed within the growth window. The structure and the magnetization of this system are investigated. We find a clear correlation between the magnetization and the unit-cell volume that we ascribe to Bi deficiency and the resultant introduction of a mixed valence on the Mn ions. On these grounds, we show that the reduced magnetization of LaxBi1-xMnO3 thin films compared to the bulk can be explained quantitatively by a simple model, taking into account the deviation from nominal composition and the Goodenough-Kanamori-Anderson rules of magnetic interactions.

  20. Growth of porous type anodic oxide films at micro-areas on aluminum exposed by laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Tatsuya [Graduate School of Engineering, Hokkaido University, N13-W8, Kita-Ku, Sapporo 060-8628 (Japan)], E-mail: kiku@eng.hokudai.ac.jp; Sakairi, Masatoshi [Graduate School of Engineering, Hokkaido University, N13-W8, Kita-Ku, Sapporo 060-8628 (Japan); Takahashi, Hideaki [Asahikawa National College of Technology, Syunkohdai, 2-2, 1-6, Asahikawa 071-8142 (Japan)

    2009-11-30

    Aluminum covered with pore-sealed anodic oxide films was irradiated with a pulsed Nd-YAG laser to remove the oxide film at micro-areas. The specimen was re-anodized for long periods to examine the growth of porous anodic oxide films at the area where substrate had been exposed by measuring current variations and morphological changes in the oxide during the re-anodizing. The chemical dissolution resistance of the pore-sealed anodic oxide films in an oxalic acid solution was also examined by measuring time-variations in rest potentials during immersion. The resistance to chemical dissolution of the oxide film became higher with increasing pore-sealing time and showed higher values at lower solution temperatures. During potentiostatic re-anodizing at five 35-{mu}m wide and 4-mm long lines for 72 h after the film was removed the measured current was found to increase linearly with time. Semicircular columnar-shaped porous type anodic oxide was found to form during the re-anodizing at the laser-irradiated area, and was found to grow radially, thus resulting in an increase in the diameter. After long re-anodizing, the central and top parts of the oxide protruded along the longitudinal direction of the laser-irradiated area. The volume expansion during re-anodizing resulted in the formation of cracks, parallel to the lines, in the oxide film formed during the first anodizing.

  1. Growth of manganese sulfide (α-MnS) thin films by thermal vacuum evaporation: Structural, morphological and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Hannachi, Amira, E-mail: amira.hannachi88@gmail.com [MALTA-Consolider Team, Institut de Ciència dels Materials – Departamento de Fisica Aplicada, University of Valencia, E-46100 Burjassot, Valencia (Spain); Université de Tunis El-Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie Analytique et Electrochimie, LR99ES15, 2092 Tunis (Tunisia); Segura, Alfredo [MALTA-Consolider Team, Institut de Ciència dels Materials – Departamento de Fisica Aplicada, University of Valencia, E-46100 Burjassot, Valencia (Spain); Maghraoui-Meherzi, Hager [Université de Tunis El-Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie Analytique et Electrochimie, LR99ES15, 2092 Tunis (Tunisia)

    2016-09-15

    MnS thin films have been successfully prepared by thermal evaporation method at different substrate temperatures using different masses of MnS powder. The prepared films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and UV–visible spectrophotometry. The XRD measurements show that the films crystallized in the pure α-MnS for substrate temperatures above 100 °C. The optical bandgap of thin films is found to be in the range of 3.2–3.3 eV. A factorial experimental design was used for determining the influence of the two experimental parameters on the films growth. - Highlights: • α-MnS films were deposited on glass and quartz substrates using the thermal evaporation technique. • The effect of substrate temperature on the properties of the MnS films has been studied. • The factorial design was used to determine the most influence parameters.

  2. Direct growth of transparent conducting Nb-doped anatase TiO2 polycrystalline films on glass

    International Nuclear Information System (INIS)

    Yamada, Naoomi; Kasai, Junpei; Hitosugi, Taro; Hoang, Ngoc Lam Huong; Nakao, Shoichiro; Hirose, Yasushi; Shimada, Toshihiro; Hasegawa, Tetsuya

    2009-01-01

    This paper proposes a novel sputter-based method for the direct growth of transparent conducting Ti 1-x Nb x O 2 (TNO) polycrystalline films on glass, without the need for any postdeposition treatments, by the use of an initial seed-layer. Anatase TNO epitaxial films grown on LaAlO 3 (100) substrates under a reducing atmosphere exhibited a low resistivity (ρ) of (3-6)x10 -4 Ω cm. On glass, however, highly resistive rutile phase polycrystalline films (ρ∼100 Ω cm) formed preferentially under the same conditions. These results suggest that epitaxial stabilization of the oxygen-deficient anatase phase occurs on lattice-matched substrates. To produce a similar effect on a glass surface, we deposited a seed-layer of anatase TNO with excellent crystallinity under an increased oxygen atmosphere. As a result, anatase phase TNO polycrystalline films could be grown even under heavily reducing atmospheres. An optimized film exhibited ρ=1.1x10 -3 Ω cm and optical absorption lower than 10% in the visible region. This ρ value is more than one order of magnitude lower than values reported for directly deposited TNO polycrystalline films. This indicates that the seed-layer method has considerable potential for producing transparent conducting TNO polycrystalline films on glass.

  3. Growth and characterization of polar and nonpolar ZnO film grown on sapphire substrates by using atomic layer deposition

    International Nuclear Information System (INIS)

    Kim, Ki-Wook; Son, Hyo-Soo; Choi, Nak-Jung; Kim, Jihoon; Lee, Sung-Nam

    2013-01-01

    We investigated the electrical and the optical properties of polar and nonpolar ZnO films grown on sapphire substrates with different crystallographic planes. High resolution X-ray results revealed that polar c-plane (0001), nonpolar m-plane (10-10) and a-plane (11-20) ZnO thin films were grown on c-plane, m- and r-sapphire substrates by atomic layer deposition, respectively. Compared with the c-plane ZnO film, nonpolar m-plane and a-plane ZnO films showed smaller surface roughness and anisotropic surface structures. Regardless of ZnO crystal planes, room temperature photoluminescence spectra represented two emissions which consisted of the near bandedge (∼ 380 nm) and the deep level emission (∼ 500 nm). The a-plane ZnO films represented better optical and electrical properties than c-plane ZnO, while m-plane ZnO films exhibited poorer optical and electrical properties than c-plane ZnO. - Highlights: • Growth and characterization of a-, c- and m-plane ZnO film by atomic layer deposition. • The a-plane ZnO represented better optical and electrical properties than c-plane ZnO. • The m-plane ZnO exhibited poorer optical and electrical properties than c-plane ZnO

  4. Epitaxial growth of YBa2Cu3O7-δ thin films on LiNbO3 substrates

    International Nuclear Information System (INIS)

    Lee, S.G.; Koren, G.; Gupta, A.; Segmuller, A.; Chi, C.C.

    1989-01-01

    In situ epitaxial growth of YBa 2 Cu 3 O 7-δ thin films on Y-cut LiNbO 3 substrates using a standard laser ablation technique is reported. Resistance of the films shows a normal metallic behavior and a very sharp ( c (R=0) of 92 K. High critical current density of J c (77 K)=2x10 5 A/cm 2 is observed, which is in accordance with epitaxial growth. Film orientation observed from x-ray diffraction spectra indicates that the c axis is normal to the substrate plane and the a axis is at 45 degree to the [11.0] direction of the hexagonal lattice of the substrate with two domains in mirror image to the (110) plane

  5. Evaporation temperature-tuned physical vapor deposition growth engineering of one-dimensional non-Fermi liquid tetrathiofulvalene tetracyanoquinodimethane thin films

    DEFF Research Database (Denmark)

    Sarkar, I.; Laux, M.; Demokritova, J.

    2010-01-01

    We describe the growth of high quality tetrathiofulvalene tetracyanoquinodimethane (TTF-TCNQ) organic charge-transfer thin films which show a clear non-Fermi liquid behavior. Temperature dependent angle resolved photoemission spectroscopy and electronic structure calculations show that the growth...... of TTF-TCNQ films is accompanied by the unfavorable presence of neutral TTF and TCNQ molecules. The quality of the films can be controlled by tuning the evaporation temperature of the precursor in physical vapor deposition method....

  6. Growth of YBCO superconducting thin films on CaF sub 2 buffered silicon

    CERN Document Server

    Bhagwat, S S; Patil, J M; Shirodkar, V S

    2000-01-01

    CaF sub 2 films were grown on silicon using the neutral cluster beam deposition technique. These films were highly crystalline and c-axis oriented. Superconducting YBCO thin films were grown on the Ca F sub 2 buffered silicon using the laser ablation technique. These films showed T sub c (onset) at 90 K and Tc(zero) at 86 K. X-ray diffraction analysis showed that the YBCO films were also oriented along the c-axis.

  7. Effect of red and yellow ginger on growth performance and total ...

    African Journals Online (AJOL)

    The objective of this study was to compare the effect of the red and yellow ginger on performance, nutrient digestibility and total antioxidant capacity of broiler chickens. In a 2×2×2+1 factorial design, a total of two hundred and sixteen, three weeks old broiler chicken with initial weight of 430 g (± 0.1g SE) were assigned to ...

  8. Attachment and growth of human bone marrow derived mesenchymal stem cells on regenerated antheraea pernyi silk fibroin films

    Energy Technology Data Exchange (ETDEWEB)

    Luan Xiying [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Wang Yong [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Duan Xiang [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Duan Qiaoyan [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Li Mingzhong [School of Materials Engineering, Suzhou University, Suzhou 215006 (China); Lu Shenzhou [School of Materials Engineering, Suzhou University, Suzhou 215006 (China); Zhang Huanxiang [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Zhang Xueguang [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China)

    2006-12-15

    Silk fibroin of the silkworm Bombyx mori has been studied extensively, while the research on Antheraea pernyi silk fibroin (A. pernyi SF) in biomaterials is only at an early stage. In this study, the attachment, morphology, growth and phenotype of human bone marrow derived mesenchymal stem cells (hBMSCs) cultured on the regenerated A. pernyi SF films were studied in vitro. The results indicated that the attachment of hBMSCs on the regenerated A. pernyi SF films was almost the same as that on the collagen films. MTT and cell counting analyses demonstrated that the growth of hBMSCs on the regenerated A. pernyi SF films was better than that on controls. Moreover, electron scanning microscopy and fluorescence-activated cell sorting assays showed that the regenerated A. pernyi SF supported hBMSCs growth and functional maintenance compared with the controls. These data suggest that the regenerated A. pernyi SF, like Bombyx mori silk fibroin (B. mori SF) and collagen, can support hBMSCs attachment, growth and phenotypic maintenance, and has better biocompatibilities for hBMSCs in vitro culture.

  9. Attachment and growth of human bone marrow derived mesenchymal stem cells on regenerated antheraea pernyi silk fibroin films

    International Nuclear Information System (INIS)

    Luan Xiying; Wang Yong; Duan Xiang; Duan Qiaoyan; Li Mingzhong; Lu Shenzhou; Zhang Huanxiang; Zhang Xueguang

    2006-01-01

    Silk fibroin of the silkworm Bombyx mori has been studied extensively, while the research on Antheraea pernyi silk fibroin (A. pernyi SF) in biomaterials is only at an early stage. In this study, the attachment, morphology, growth and phenotype of human bone marrow derived mesenchymal stem cells (hBMSCs) cultured on the regenerated A. pernyi SF films were studied in vitro. The results indicated that the attachment of hBMSCs on the regenerated A. pernyi SF films was almost the same as that on the collagen films. MTT and cell counting analyses demonstrated that the growth of hBMSCs on the regenerated A. pernyi SF films was better than that on controls. Moreover, electron scanning microscopy and fluorescence-activated cell sorting assays showed that the regenerated A. pernyi SF supported hBMSCs growth and functional maintenance compared with the controls. These data suggest that the regenerated A. pernyi SF, like Bombyx mori silk fibroin (B. mori SF) and collagen, can support hBMSCs attachment, growth and phenotypic maintenance, and has better biocompatibilities for hBMSCs in vitro culture

  10. Rapid growth of amorphous carbon films on the inner surface of micron-thick and hollow-core fibers

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Longfei [Fujian Key Laboratory for Plasma and Magnetic Resonance, Department of Electric Science, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Liu, Dongping, E-mail: Dongping.liu@dlnu.edu.cn [Fujian Key Laboratory for Plasma and Magnetic Resonance, Department of Electric Science, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Zhou, Xinwei [Department of Mechanical Engineering, Zhejiang University, Zhejiang 310007 (China); Song, Ying [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Ni, Weiyuan [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Niu, Jinhai; Fan, Hongyu [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China)

    2013-10-01

    Ultrathick (> 25 μm) carbon films were obtained on the inner surface of hollow and micron-thick quartz fibers by confining CH{sub 4}/He or C{sub 2}H{sub 2}/He microplasmas in their hollow cores. The resulting carbon films were studied by using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The microplasma-enhanced chemical vapor deposition (CVD) technique resulted in the uniform growth of amorphous carbon films on the inner surface of very long (> 1 m) hollow-core fibers. Film deposition is performed by using microplasmas at atmospheric pressure and at 50 Pa. The carbon films obtained with the latter show the smooth inner surfaces and the well continuity across the film/optical fiber. Low-pressure CH{sub 4}/He and C{sub 2}H{sub 2}/He microplasmas can lead to a rapid growth (∼ 2.00 μm/min) of carbon films with their thickness of > 25 μm. The optical emission measurements show that various hydrocarbon species were formed in these depositing microplasmas due to the collisions between CH{sub 4}/C{sub 2}H{sub 2} molecules and energetic species. The microplasma-enhanced CVD technique running without the complicated fabrication processes shows its potentials for rapidly depositing the overlong carbon tubes with their inner diameters of tens of microns. - Highlights: • The microplasma device is applied for coating deposition inside hollow-core fibers. • The microplasma device results in > 25 μm-thick carbon films. • The microplasma device is simple for deposition of ultralong carbon tubes.

  11. Serum IGF-1 is insufficient to restore skeletal size in the total absence of the growth hormone receptor

    Science.gov (United States)

    Wu, Yingjie; Sun, Hui; Basta-Pljakic, Jelena; Cardoso, Luis; Kennedy, Oran D; Jasper, Hector; Domené, Horacio; Karabatas, Liliana; Guida, Clara; Schaffler, Mitchell B; Rosen, Clifford J; Yakar, Shoshana

    2013-01-01

    States of growth hormone (GH) resistance, such those observed in Laron’s dwarf patients, are characterized by mutations in the GH receptor (GHR), decreased serum and tissue IGF-1 levels, impaired glucose tolerance, and impaired skeletal acquisition. IGF-1 replacement therapy in such patients increases growth velocity but does not normalize growth. Herein we combined the GH-resistant (GHR knockout, GHRKO) mouse model with mice expressing the hepatic Igf-1 transgene (HIT) to generate the GHRKO-HIT mouse model. In GHRKOHIT mice, serum IGF-1 levels were restored via transgenic expression of Igf-1 allowing us to study how endocrine IGF-1 affects growth, metabolic homeostasis, and skeletal integrity. We show that in a GH-resistant state, normalization of serum IGF-1 improved body adiposity and restored glucose tolerance but was insufficient to support normal skeletal growth, resulting in an osteopenic skeletal phenotype. The inability of serum IGF-1 to restore skeletal integrity in the total absence of GHR likely resulted from reduced skeletal Igf-1 gene expression, blunted GH-mediated effects on the skeleton that are independent of serum or tissue IGF-1, and from poor delivery of IGF-1 to the tissues. These findings are consistent with clinical data showing that IGF-I replacement therapy in patients with Laron’s syndrome does not achieve full skeletal growth. PMID:23456957

  12. A simple non-equilibrium, statistical-physics toy model of thin-film growth

    International Nuclear Information System (INIS)

    Ochab, Jeremi K; Nagel, Hannes; Janke, Wolfhard; Waclaw, Bartlomiej

    2015-01-01

    We present a simple non-equilibrium model of mass condensation with Lennard–Jones interactions between particles and the substrate. We show that when some number of particles is deposited onto the surface and the system is left to equilibrate, particles condense into an island if the density of particles becomes higher than some critical density. We illustrate this with numerically obtained phase diagrams for three-dimensional systems. We also solve a two-dimensional counterpart of this model analytically and show that not only the phase diagram but also the shape of the cross-sections of three-dimensional condensates qualitatively matches the two-dimensional predictions. Lastly, we show that when particles are being deposited with a constant rate, the system has two phases: a single condensate for low deposition rates, and multiple condensates for fast deposition. The behaviour of our model is thus similar to that of thin film growth processes, and in particular to Stranski–Krastanov growth. (paper)

  13. Phase competition in the growth of SrCoOx/LaAlO3 thin films

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    2018-02-01

    Full Text Available The reversible topotactic phase transformation between brownmillerite SrCoO2.5 to perovskite SrCoO3 has attracted more and more attention for potential applications as solid oxide fuels and electrolysis cells. However, the relatively easy transformation result from small thermal stable energy barriers between the two phases leads to unstable the structures. In the paper, amounts of SrCoO3-δ films have been prepared by pulsed laser deposition at optimized growth conditions with the temperature range of 590-720°C. The X-ray diffraction (XRD results demonstrated that a phase competition emerged around 650°C. The Gibbs free energies of two phases at high temperature revealed the difference of stability of these two phases under different growth temperature. The optical spectroscopies and X-ray photoelectron spectroscopies were used to verify the electronic structure and chemical state differences between the two phases with distinct crystal structures.

  14. Characteristics of growth of complex ferroelectric oxide films by plasma-ion sputtering

    Science.gov (United States)

    Mukhortov, V. M.; Golovko, Yu. I.; Mukhortov, Vl. M.; Dudkevich, V. P.

    1981-02-01

    An experimental investigation was made of the process of growth of a complex oxide film, such as BaTiO3 or (Ba, Sr)TiO3, by plasma-ion sputtering. It was found that ion bombardment of a ceramic target knocked out neutral excited atoms. These atoms lost energy away from the target by collisions and at a certain critical distance hcr they were capable of oxidation to produce BaO, TiO, TiO2, and SrO. Therefore, depending on the distance between the cathode and the substrate, the “construction” material arrived in the form of atoms or molecules of simple oxides. These two (atomic and molecular) deposition mechanisms corresponded to two mechanisms of synthesis and crystallization differing in respect of the dependences of the growth rate, unit cell parameters, and other structural properties on the deposition temperature. The role of re-evaporation and of oxidation-reduction processes was analyzed.

  15. Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification.

    Science.gov (United States)

    Lassnig, R; Hollerer, M; Striedinger, B; Fian, A; Stadlober, B; Winkler, A

    2015-11-01

    In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p ++ -silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3-4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact-channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility.

  16. Passive film growth on carbon steel and its nanoscale features at various passivating potentials

    International Nuclear Information System (INIS)

    Li, Yuan; Cheng, Y. Frank

    2017-01-01

    Highlights: • Imaged the topography of passivated steel at various film-forming potentials. • Characterized the nanoscale features of passive films. • Determined the composition of passive films formed at various potentials. - Abstract: In this work, the passivation and topographic sub-structure of passive films on a carbon steel in a carbonate/bicarbonate solution was characterized by electrochemical measurements, atomic force microscopy and X-ray photoelectron spectroscopy. When passivating at a potential near the active-passive transition, the film contains the mixture of Fe_3O_4, Fe_2O_3 and FeOOH, with numerous nanoscale features. As the film-forming potential shifts positively, the passive film becomes more compact and the nanoscale features disappear. When the film is formed at a passive potential where the oxygen evolution is enabled, the content of FeOOH in the film increases, resulting in an amorphous topography and reduced corrosion resistance.

  17. Growth of Cu(In,Al)(Se,S)2 thin films by selenization and sulfurization for a wide bandgap absorber

    International Nuclear Information System (INIS)

    Fujiwara, C.; Kawasaki, Y.; Sato, T.; Sugiyama, M.; Chichibu, S.F.

    2010-01-01

    Full text : Chalcopyrite structure Cu(In 1 .xAlx)(S y Se 1 -y) 2 (CIASS) alloys are attracting attention as promising candidates for the light-absorbing medium of high conversion efficiency, low cost, and lightweight solar cells. In addition, according to the wide variation in the bandgap energy (1.0-3.5eV), multiple-junction or tandem solar cells able to be fabricated using CIASS films of different compositions, x and y. In fact, several research groups have recently fabricated Cu(In,Al)Se 2 -based solar cells, and a high μ of 16.9 percent has been demonstrated. The sulfurization following selenization of Cu(In,Ga)Se2 (CIGS) films is believed to be promising for bandgap engineering of absorber material. Furthermore, it has been reported that the controlled incorporation of sulfur into CIGS films reduces the carrier recombination in the space charge region due to the deep trap states. Therefore, the sulfurization following selenization is expected to be used as a method of growth of CIASS films. However, sulfurization condition following selenization for obtaining CIASS films has not been clarified. The crystal growth of CIASS must be studied for solar cell applications. In this study, the advantages of using sulfurization for the growth of CIASS will be presented. Cu-In-Al precursors were selenized using diethylselenide (DESe) at 515-570 degrees Celsium for 60- 90 min under atmospheric pressure. The flow rates of DESe and N 2 carrier gases were 35 imol/min and 2 L/min, respectively. The films were then sulfurized at 550 degrees Celsium using S vapor. These films were characterized by SEM, EDX, XRD, and PL measurements. Using the selenization and sulfurization technique, polycrystalline Cu(In,Al)Se 2 , CuIn(Se,S) 2 , CuInS 2 films with thickness of approximately 2.0 im were formed without additional annealing. The films adhered well to the Mo/SLG substrate, which was confirmed by the peeling test. Phase separations, i.e. distinct peaks corresponding to CuInSe 2

  18. Si(001):B gas-source molecular-beam epitaxy: Boron surface segregation and its effect on film growth kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H.; Glass, G.; Spila, T.; Taylor, N.; Park, S.Y.; Abelson, J.R.; Greene, J.E. [Department of Materials Science, Coordinated Science Laboratory, and Materials Research Laboratory, University of Illinois, 1101 West Springfield, Urbana, Illinois 61801 (United States)

    1997-09-01

    B-doped Si(001) films, with concentrations C{sub B} up to 1.7{times}10{sup 22}cm{sup {minus}3}, were grown by gas-source molecular-beam epitaxy from Si{sub 2}H{sub 6} and B{sub 2}H{sub 6} at T{sub s}=500{endash}800{degree}C. D{sub 2} temperature-programed desorption (TPD) spectra were then used to determine B coverages {theta}{sub B} as a function of C{sub B} and T{sub s}. In these measurements, as-deposited films were flash heated to desorb surface hydrogen, cooled, and exposed to atomic deuterium until saturation coverage. Strong B surface segregation was observed with surface-to-bulk B concentration ratios ranging up to 1200. TPD spectra exhibited {beta}{sub 2} and {beta}{sub 1} peaks associated with dideuteride and monodeuteride desorption as well as lower-temperature B-induced peaks {beta}{sub 2}{sup {asterisk}} and {beta}{sub 1}{sup {asterisk}}. Increasing {theta}{sub B} increased the area under {beta}{sub 2}{sup {asterisk}} and {beta}{sub 1}{sup {asterisk}} at the expense of {beta}{sub 2} and {beta}{sub 1} and decreased the total D coverage {theta}{sub D}. The TPD results were used to determine the B segregation enthalpy, {minus}0.53eV, and to explain and model the effects of high B coverages on Si(001) growth kinetics. Film deposition rates R increase by {ge}50{percent} with increasing C{sub B}{tilde {gt}}1{times}10{sup 19}cm{sup {minus}3} at T{sub s}{le}550{degree}C, due primarily to increased H desorption rates from B-backbonded Si adatoms, and decrease by corresponding amounts at T{sub s}{ge}600{degree}C due to decreased adsorption site densities. At T{sub s}{ge}700{degree}C, high B coverages also induce {l_brace}113{r_brace} facetting. {copyright} {ital 1997 American Institute of Physics.}

  19. Order-disorder criticality, wetting, and morphological phase transitions in the irreversible growth of far-from-equilibrium magnetic films

    International Nuclear Information System (INIS)

    Candia, J.Julian; Albano, E.V.Ezequiel V.

    2003-01-01

    An exhaustive numerical investigation of the growth of magnetic films in confined (d+1)-dimensional stripped geometries (d=1,2) is carried out by means of extensive Monte Carlo simulations. Films in contact with a thermal bath at temperature T, are grown by adding spins having two possible orientations and considering ferromagnetic (nearest-neighbor) interactions. At low temperatures, thin films of thickness L are constituted by a sequence of well-ordered domains of average length l D >>L. These domains have opposite magnetization. So, the films exhibit 'spontaneous magnetization reversal' during the growth process. Such reversal occurs within a short characteristic length l R , such that l D >>l R ∼L. Furthermore, it is found that for d=1 the system is non-critical, while a continuous order-disorder phase transition at finite temperature takes place in the d=2 case. Using standard finite-size scaling procedures, the critical temperature and some relevant critical exponents are determined. Finally, the growth of magnetic films in (2+1) dimensions with competing short-range magnetic fields acting along the confinement walls is studied. Due to the antisymmetric condition considered, an interface between domains with spins having opposite orientation develops along the growing direction. Such an interface undergoes a localization-delocalization transition that is the precursor of a wetting transition in the thermodynamic limit. Furthermore, the growing interface also undergoes morphological transitions in the growth mode. A comparison between the well-studied equilibrium Ising model and the studied irreversible magnetic growth model is performed throughout. Although valuable analogies are encountered, it is found that the non-equilibrium nature of the latter introduces new and rich physical features of interest

  20. 3C-SiC epitaxial films deposited by reactive magnetron sputtering: Growth, characterization and device development

    Energy Technology Data Exchange (ETDEWEB)

    Wahab, Qamar ul.

    1994-01-01

    Epitaxial 3C-SiC films were grown on silicon substrates by reactive magnetron sputtering of pure Si target in a mixed Ar-CH[sub 4] discharges. Films were grown on Si(001), and 4 degrees off-oriented (001) substrates. Epitaxial 3C-SiC films with sharp interface to Si substrates have been grown at substrate temperatures [<=] 900 degrees C. Above 900 degrees C interfacial reaction starts resulting in a rough SiC/Si interface. The carbon content as well as the crystalline structure was also found to be strongly dependent on CH[sub 4] partial pressure (PCH[sub 4]) and stoichiometric composition can only be obtained in a narrow PCH[sub 4] range. Films grown on Si(001) substrates contained anti domain boundaries as evident by cross-sectional transmission electron microscopy (XTEM). Films grown on (111)-oriented substrates were epitaxial at 850 degrees C but contained double positioning domains as determined by X-ray diffraction analysis and XTEM. High quality films were obtained on 4 degrees off-oriented Si(001) substrates at T[sub s]=850 degrees C and PCH[sub 4]=0.6 mTorr. Films grown on off-oriented substrates showed atomically sharp interface to Si and also a smooth top surface. SiO[sub 2] layer grown on such films showed atomically sharp oxide/film interface. Also the growth of epitaxial Si films on top of SiC films was realized. Au-Schottky diodes fabricated on (001)-oriented 3C-SiC films showed good rectification with a leakage current density = 4 [mu]A cm[sup -2], a breakdown voltage of -15 V, an ideality factor of 1.27 and a barrier height of 1.04 eV. Metal oxide semiconductor structures were fabricated by thermally grown SiO[sub 2] on (111)-oriented SiC films. The capacitance-voltage measurements showed the accumulation, depletion and deep depletion region in the C-V curve. The interface trap densities were 3-7 x 10[sup 11] cm[sup -2] eV[sup -1]. Finally 3C-SiC/Si heterojunction diodes processed showed good rectification and the diode had a breakdown at -110 V.

  1. 3C-SiC epitaxial films deposited by reactive magnetron sputtering: Growth, characterization and device development

    International Nuclear Information System (INIS)

    Wahab, Qamar ul.

    1994-01-01

    Epitaxial 3C-SiC films were grown on silicon substrates by reactive magnetron sputtering of pure Si target in a mixed Ar-CH 4 discharges. Films were grown on Si(001), and 4 degrees off-oriented (001) substrates. Epitaxial 3C-SiC films with sharp interface to Si substrates have been grown at substrate temperatures ≤ 900 degrees C. Above 900 degrees C interfacial reaction starts resulting in a rough SiC/Si interface. The carbon content as well as the crystalline structure was also found to be strongly dependent on CH 4 partial pressure (PCH 4 ) and stoichiometric composition can only be obtained in a narrow PCH 4 range. Films grown on Si(001) substrates contained anti domain boundaries as evident by cross-sectional transmission electron microscopy (XTEM). Films grown on (111)-oriented substrates were epitaxial at 850 degrees C but contained double positioning domains as determined by X-ray diffraction analysis and XTEM. High quality films were obtained on 4 degrees off-oriented Si(001) substrates at T s =850 degrees C and PCH 4 =0.6 mTorr. Films grown on off-oriented substrates showed atomically sharp interface to Si and also a smooth top surface. SiO 2 layer grown on such films showed atomically sharp oxide/film interface. Also the growth of epitaxial Si films on top of SiC films was realized. Au-Schottky diodes fabricated on (001)-oriented 3C-SiC films showed good rectification with a leakage current density = 4 μA cm -2 , a breakdown voltage of -15 V, an ideality factor of 1.27 and a barrier height of 1.04 eV. Metal oxide semiconductor (MOS) structures were fabricated by thermally grown SiO 2 on (111)-oriented SiC films. The capacitance-voltage measurements showed the accumulation, depletion and deep depletion region in the C-V curve. The interface trap densities were 3-7 x 10 11 cm -2 eV -1 . Finally 3C-SiC/Si heterojunction diodes processed showed good rectification and the diode had a breakdown at -110 V. 59 refs, figs, tabs

  2. Cell adhesion and growth on ultrananocrystalline diamond and diamond-like carbon films after different surface modifications

    Energy Technology Data Exchange (ETDEWEB)

    Miksovsky, J. [Institute of Nanostructure Technologies and Analytics, Center for Interdisciplinary Nanostructure Science and Technology, University of Kassel (Germany); Institute of Physics ASCR, Prague (Czech Republic); Czech Technical University in Prague, Faculty of Biomedical Engineering, Kladno (Czech Republic); Voss, A. [Institute of Nanostructure Technologies and Analytics, Center for Interdisciplinary Nanostructure Science and Technology, University of Kassel (Germany); Kozarova, R. [Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia (Bulgaria); Kocourek, T.; Pisarik, P. [Institute of Physics ASCR, Prague (Czech Republic); Czech Technical University in Prague, Faculty of Biomedical Engineering, Kladno (Czech Republic); Ceccone, G. [Unit Nanobiosciences, European Commission Joint Research Centre, Ispra (Italy); Kulisch, W. [Institute of Nanostructure Technologies and Analytics, Center for Interdisciplinary Nanostructure Science and Technology, University of Kassel (Germany); Jelinek, M. [Institute of Physics ASCR, Prague (Czech Republic); Czech Technical University in Prague, Faculty of Biomedical Engineering, Kladno (Czech Republic); Apostolova, M.D. [Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia (Bulgaria); Reithmaier, J.P. [Institute of Nanostructure Technologies and Analytics, Center for Interdisciplinary Nanostructure Science and Technology, University of Kassel (Germany); Popov, C., E-mail: popov@ina.uni-kassel.de [Institute of Nanostructure Technologies and Analytics, Center for Interdisciplinary Nanostructure Science and Technology, University of Kassel (Germany)

    2014-04-01

    Graphical abstract: - Highlights: • UNCD and DLC films were modified by UV/O{sub 3} treatments, O{sub 2} or NH{sub 3}-containing plasmas. • Surface composition, wettability and surface energy change upon modifications. • Higher efficiency of UNCD modifications was observed. • Cell attachment and growth were influenced by the surface termination and roughness. - Abstract: Diamond and diamond-like carbon (DLC) films possess a set of excellent physical and chemical properties which together with a high biocompatibility make them attractive candidates for a number of medical and biotechnological applications. In the current work thin ultrananocrystalline diamond (UNCD) and DLC films were comparatively investigated with respect to cell attachment and proliferation after different surface modifications. The UNCD films were prepared by microwave plasma enhanced chemical vapor deposition, the DLC films by pulsed laser deposition (PLD). The films were comprehensively characterized with respect to their basic properties, e.g. crystallinity, morphology, chemical bonding nature, etc. Afterwards the UNCD and DLC films were modified applying O{sub 2} or NH{sub 3}/N{sub 2} plasmas and UV/O{sub 3} treatments to alter their surface termination. The surface composition of as-grown and modified samples was studied by X-ray photoelectron spectroscopy (XPS). Furthermore the films were characterized by contact angle measurements with water, formamide, 1-decanol and diiodomethane; from the results obtained the surface energy with its dispersive and polar components was calculated. The adhesion and proliferation of MG63 osteosarcoma cells on the different UNCD and DLC samples were assessed by measurement of the cell attachment efficiency and MTT assays. The determined cell densities were compared and correlated with the surface properties of as-deposited and modified UNCD and DLC films.

  3. Epitaxial growth and control of the sodium content in Na{sub x}CoO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Sandra; Komissinskiy, Philipp [Institute for Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Major, Marton [Institute for Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); WIGNER RCP, RMKI, H-1525 Budapest, P.O.B. 49 (Hungary); Donner, Wolfgang [Institute for Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Alff, Lambert, E-mail: alff@oxide.tu-darmstadt.de [Institute for Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2013-10-31

    Single-phase c-axis oriented Na{sub x}CoO{sub 2} thin films were grown on (001) SrTiO{sub 3} single-crystal substrates, using pulsed laser deposition. X-ray diffraction analysis indicates the epitaxial growth of Na{sub x}CoO{sub 2} thin films in two domains, rotated in-plane by 15 and 45 degrees relative to [100] SrTiO{sub 3}. The sodium stoichiometry x of the films can be controlled in a range of 0.38 < x < 0.84 by in-situ post-deposition annealing the Na{sub x}CoO{sub 2} films at 720 – 760 °C in oxygen for 10 – 30 min. γ - Na{sub x}CoO{sub 2} films are obtained with a full width at half maximum of the (002) Na{sub x}CoO{sub 2} rocking curve below 0.2 degrees. The post-deposition annealing can substitute commonly used chemical deintercalation of Na which is typically associated with a loss in crystallinity. - Highlights: • Single phase Na{sub x}CoO{sub 2} thin films grown by pulsed laser deposition • Epitaxial relations of Na{sub x}CoO{sub 2} thin films on (001) SrTiO{sub 3} substrates • Multi-domain thin films • Control of sodium content by in-situ annealing of Na{sub x}CoO{sub 2} thin films.

  4. Optimal fetal growth for the Caucasian singleton and assessment of appropriateness of fetal growth: an analysis of a total population perinatal database

    Directory of Open Access Journals (Sweden)

    Lawrence David M

    2005-05-01

    Full Text Available Abstract Background The appropriateness of an individual's intra uterine growth is now considered an important determinant of both short and long term outcomes, yet currently used measures have several shortcomings. This study demonstrates a method of assessing appropriateness of intrauterine growth based on the estimation of each individual's optimal newborn dimensions from routinely available perinatal data. Appropriateness of growth can then be inferred from the ratio of the value of the observed dimension to that of the optimal dimension. Methods Fractional polynomial regression models including terms for non-pathological determinants of fetal size (gestational duration, fetal gender and maternal height, age and parity were used to predict birth weight, birth length and head circumference from a population without any major risk factors for sub-optimal intra-uterine growth. This population was selected from a total population of all singleton, Caucasian births in Western Australia 1998–2002. Births were excluded if the pregnancy was exposed to factors known to influence fetal growth pathologically. The values predicted by these models were treated as the optimal values, given infant gender, gestational age, maternal height, parity, and age. Results The selected sample (N = 62,746 comprised 60.5% of the total Caucasian singleton birth cohort. Equations are presented that predict optimal birth weight, birth length and head circumference given gestational duration, fetal gender, maternal height, age and parity. The best fitting models explained 40.5% of variance for birth weight, 32.2% for birth length, and 25.2% for head circumference at birth. Conclusion Proportion of optimal birth weight (length or head circumference provides a method of assessing appropriateness of intrauterine growth that is less dependent on the health of the reference population or the quality of their morphometric data than is percentile position on a birth weight

  5. Effect of growth interruptions on TiO{sub 2} films deposited by plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Li, D., E-mail: dyli@yzu.edu.cn [College of Mechanical Engineering, Yangzhou University, Yangzhou, 225127 (China); Goullet, A. [Institut des Matériaux Jean Rouxel (IMN), UMR CNRS 6502, 2 rue de la Houssinière, 44322, Nantes (France); Carette, M. [Institut d’Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré, 59652, Villeneuve d' Ascq (France); Granier, A. [Institut des Matériaux Jean Rouxel (IMN), UMR CNRS 6502, 2 rue de la Houssinière, 44322, Nantes (France); Landesman, J.P. [Institut de Physique de Rennes, UMR CNRS 6251, 263 av. Général Leclerc, 35042, Rennes (France)

    2016-10-01

    TiO{sub 2} films of ∼300 nm were deposited at low temperature (<140 °C) and pressure (0.4 Pa) using plasma enhanced chemical vapour deposition at the floating potential (V{sub f}) or the substrate self-bias voltage (V{sub b}) of −50 V. The impact of growth interruptions on the morphology, microstructure and optical properties of the films was investigated. The interruptions were carried out by stopping the plasma generation and gas injection once the increase of the layer thickness during each deposition step was about ∼100 nm. In one case of V{sub f}, the films of ∼300 nm exhibit a columnar morphology consisting of a bottom dense layer, an intermediate gradient layer and a top roughness layer. But the growth interruptions result in an increase of the dense layer thickness and a decrease of surface roughness. The film inhomogeneity has been identified by the in-situ real-time evolution of the kinetic ellipsometry (KE) parameters and the modeling process of spectroscopic ellipsometry (SE). The discrepancy of the refractive index measured by SE between bottom and upper layers can be reduced by growth interruptions. In the other case of V{sub b} = −50 V, the films exhibit a more compact arrangement which is homogeneous along the growth direction as confirmed by KE and SE. Both of Fourier transform infrared spectra and X-ray diffraction illustrate a phase transformation from anatase to rutile with the bias of −50 V, and also evidenced on the evolution of the refractive index dispersion curves. And a greatly increase of the refractive indice in the transparent range can be identified. However, the growth interruptions seem to have no influence on the morphology and optical properties in this case. - Highlights: • TiO{sub 2} films deposited by plasma processes at low temperature and pressure. • Influence of growth interruptions on structural and optical properties. • In-situ real-time ellipsometry measurements on film properties. • Structural and

  6. Growth and characterization of III-N ternary thin films by plasma assisted atomic layer epitaxy at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Nepal, Neeraj; Anderson, Virginia R.; Hite, Jennifer K.; Eddy, Charles R.

    2015-08-31

    We report the growth and characterization of III-nitride ternary thin films (Al{sub x}Ga{sub 1−x}N, In{sub x}Al{sub 1−x}N and In{sub x}Ga{sub 1−x}N) at ≤ 500 °C by plasma assisted atomic layer epitaxy (PA-ALE) over a wide stoichiometric range including the range where phase separation has been an issue for films grown by molecular beam epitaxy and metal organic chemical vapor deposition. The composition of these ternaries was intentionally varied through alterations in the cycle ratios of the III-nitride binary layers (AlN, GaN, and InN). By this digital alloy growth method, we are able to grow III-nitride ternaries by PA-ALE over nearly the entire stoichiometry range including in the spinodal decomposition region (x = 15–85%). These early efforts suggest great promise of PA-ALE at low temperatures for addressing miscibility gap challenges encountered with conventional growth methods and realizing high performance optoelectronic and electronic devices involving ternary/binary heterojunctions, which are not currently possible. - Highlights: • III-N ternaries grown at ≤ 500 °C by plasma assisted atomic layer epitaxy • Growth of InGaN and AlInN in the spinodal decomposition region (15–85%) • Epitaxial, smooth and uniform III-N film growth at low temperatures.

  7. Growth and characterization of III-N ternary thin films by plasma assisted atomic layer epitaxy at low temperatures

    International Nuclear Information System (INIS)

    Nepal, Neeraj; Anderson, Virginia R.; Hite, Jennifer K.; Eddy, Charles R.

    2015-01-01

    We report the growth and characterization of III-nitride ternary thin films (Al x Ga 1−x N, In x Al 1−x N and In x Ga 1−x N) at ≤ 500 °C by plasma assisted atomic layer epitaxy (PA-ALE) over a wide stoichiometric range including the range where phase separation has been an issue for films grown by molecular beam epitaxy and metal organic chemical vapor deposition. The composition of these ternaries was intentionally varied through alterations in the cycle ratios of the III-nitride binary layers (AlN, GaN, and InN). By this digital alloy growth method, we are able to grow III-nitride ternaries by PA-ALE over nearly the entire stoichiometry range including in the spinodal decomposition region (x = 15–85%). These early efforts suggest great promise of PA-ALE at low temperatures for addressing miscibility gap challenges encountered with conventional growth methods and realizing high performance optoelectronic and electronic devices involving ternary/binary heterojunctions, which are not currently possible. - Highlights: • III-N ternaries grown at ≤ 500 °C by plasma assisted atomic layer epitaxy • Growth of InGaN and AlInN in the spinodal decomposition region (15–85%) • Epitaxial, smooth and uniform III-N film growth at low temperatures

  8. A multiscale coupled finite-element and phase-field framework to modeling stressed grain growth in polycrystalline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jamshidian, M., E-mail: jamshidian@cc.iut.ac.ir [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); Thamburaja, P., E-mail: prakash.thamburaja@gmail.com [Department of Mechanical & Materials Engineering, Universiti Kebangsaan Malaysia (UKM), Bangi 43600 (Malaysia); Rabczuk, T., E-mail: timon.rabczuk@tdt.edu.vn [Division of Computational Mechanics, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City (Viet Nam)

    2016-12-15

    A previously-developed finite-deformation- and crystal-elasticity-based constitutive theory for stressed grain growth in cubic polycrystalline bodies has been augmented to include a description of excess surface energy and grain-growth stagnation mechanisms through the use of surface effect state variables in a thermodynamically-consistent manner. The constitutive theory was also implemented into a multiscale coupled finite-element and phase-field computational framework. With the material parameters in the constitutive theory suitably calibrated, our three-dimensional numerical simulations show that the constitutive model is able to accurately predict the experimentally-determined evolution of crystallographic texture and grain size statistics in polycrystalline copper thin films deposited on polyimide substrate and annealed at high-homologous temperatures. In particular, our numerical analyses show that the broad texture transition observed in the annealing experiments of polycrystalline thin films is caused by grain growth stagnation mechanisms. - Graphical abstract: - Highlights: • Developing a theory for stressed grain growth in polycrystalline thin films. • Implementation into a multiscale coupled finite-element and phase-field framework. • Quantitative reproduction of the experimental grain growth data by simulations. • Revealing the cause of texture transition to be due to the stagnation mechanisms.

  9. Mocvd Growth of Group-III Nitrides on Silicon Carbide: From Thin Films to Atomically Thin Layers

    Science.gov (United States)

    Al Balushi, Zakaria Y.

    Group-III nitride semiconductors (AlN, GaN, InN and their alloys) are considered one of the most important class of materials for electronic and optoelectronic devices. This is not limited to the blue light-emitting diode (LED) used for efficient solid-state lighting, but other applications as well, such as solar cells, radar and a variety of high frequency power electronics, which are all prime examples of the technological importance of nitride based wide bandgap semiconductors in our daily lives. The goal of this dissertation work was to explore and establish new growth schemes to improve the structural and optical properties of thick to atomically thin films of group-III nitrides grown by metalorganic chemical vapor deposition (MOCVD) on SiC substrates for future novel devices. The first research focus of this dissertation was on the growth of indium gallium nitride (InGaN). This wide bandgap semiconductor has attracted much research attention as an active layer in LEDs and recently as an absorber material for solar cells. InGaN has superior material properties for solar cells due to its wavelength absorption tunability that nearly covers the entire solar spectrum. This can be achieved by controlling the indium content in thick grown material. Thick InGaN films are also of interest as strain reducing based layers for deep-green and red light emitters. The growth of thick films of InGaN is, however, hindered by several combined problems. This includes poor incorporation of indium in alloys, high density of structural and morphological defects, as well as challenges associated with the segregation of indium in thick films. Overcoming some of these material challenges is essential in order integrate thick InGaN films into future optoelectronics. Therefore, this dissertation research investigated the growth mechanism of InGaN layers grown in the N-polar direction by MOCVD as a route to improve the structural and optical properties of thick InGaN films. The growth

  10. Influence of growth time on crystalline structure, morphologic and optical properties of In2O3 thin films

    International Nuclear Information System (INIS)

    Attaf, A.; Bouhdjar, A.; Saidi, H.; Benkhetta, Y.; Bendjedidi, H.; Nouadji, M.; Lehraki, N.

    2015-01-01

    Indium oxide (In 2 O 3 ) thin films are successfully deposited on glass substrate at different deposition timings by ultrasonic spray technique using Indium chloride (InCl 3 ) material source witch is prepared with dissolvent Ethanol (C 2 H 5 -OH), the physical properties of these films are characterized by XRD, MEB,UV-visible. XRD analysis revealed that the films are polycrystalline in nature having centered cubic crystal structure and symmetry space group I2 1 3 with a preferred grain orientation along to (222) plane when the deposition time changes from 4 to 10 min but after t = 10 min, especially when t = 13 min we found that the majority of grains preferred the plane (400). The maximum value of grain size D = 61,51 nm is attained for In 2 O 3 films grown at t =10 min. the average transmittance is about 72%, The optical gap energy is found to decrease from 3.8 to 3.66 eV with growth time Increased from 4 to 10 min but after t = 10 min the value of E g will increase to 3.72 eV. A systematic study on the influence of growth time on the properties of In 2 O 3 thin films deposited by ultrasonic spray at 400 °C has been reported

  11. Influence of growth time on crystalline structure, morphologic and optical properties of In2O3 thin films

    Science.gov (United States)

    Attaf, A.; Bouhdjar, A.; Saidi, H.; Benkhetta, Y.; Bendjedidi, H.; Nouadji, M.; Lehraki, N.

    2015-03-01

    Indium oxide (In2O3) thin films are successfully deposited on glass substrate at different deposition timings by ultrasonic spray technique using Indium chloride (InCl3) material source witch is prepared with dissolvent Ethanol (C2H5-OH), the physical properties of these films are characterized by XRD, MEB,UV-visible. XRD analysis revealed that the films are polycrystalline in nature having centered cubic crystal structure and symmetry space group I213 with a preferred grain orientation along to (222) plane when the deposition time changes from 4 to 10 min but after t = 10 min, especially when t = 13 min we found that the majority of grains preferred the plane (400). The maximum value of grain size D = 61,51 nm is attained for In2O3 films grown at t =10 min. the average transmittance is about 72%, The optical gap energy is found to decrease from 3.8 to 3.66 eV with growth time Increased from 4 to 10 min but after t = 10 min the value of Eg will increase to 3.72 eV. A systematic study on the influence of growth time on the properties of In2O3 thin films deposited by ultrasonic spray at 400 °C has been reported.

  12. Ab initio thermodynamics for the growth of ultra-thin Cu film on a perfect Mg O(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhukovskii, Yuri F. [Institute for Solid State Physics, University of Latvia, Kengaraga str. 8, Riga LV-1063 (Latvia)]. E-mail: quantzh@latnet.lv; Fuks, David [Materials Engineering Department, Ben-Gurion University of the Negev, POB 653, Beer-Sheva IL-84105 (Israel); Kotomin, Eugene A. [Institute for Solid State Physics, University of Latvia, Kengaraga str. 8, Riga LV-1063 (Latvia); Dorfman, Simon [Department of Physics, Israel Institute of Technology-Technion, Haifa IL-32000 (Israel)

    2005-12-15

    Controlled growth of thin metallic films on oxide substrates is important for numerous micro-and nano electronic applications. Our ab initio study is devoted to the periodic slab simulations for a series of ordered 2a Cu superlattices on the regular Mg O(001) substrate. Submonolayer and monolayer substrate Cu coverages were calculated using the Daft-Gaga method, as implemented into the Crystal-98 code. The results of ab initio calculations have been combined with thermodynamic theory which allows US to predict the growth mode of ultra-thin metal films (spinodal decomposition vs. nucleation-and-growth regime) as a function of the metal coverage and the temperature, and to estimate the metal density in clusters. We show that 3a cluster formation becomes predominant already at low Cu coverages, in agreement with the experiment.

  13. Growth of crystallized Ge films from VHF inductively-coupled plasma of H2-diluted GeH4

    International Nuclear Information System (INIS)

    Sakata, T.; Makihara, K.; Murakami, H.; Higashi, S.; Miyazaki, S.

    2007-01-01

    We have studied the Ge crystalline nucleation and film growth on quartz substrate at 250 deg. C from inductively-coupled plasma (ICP) of GeH 4 diluted with H 2 . The ICP was generated by supplying 60 MHz power to an external single-turn antenna which was placed on a quartz plate window of a stainless steel reactor and parallel to the substrate. We have found that the growth rate is significantly increased when the preferential growth of the (110) plane becomes pronounced after the formation of randomly-oriented crystalline network. The (110) oriented Ge films, of which average crystallinity is as high as 70%. The integrated intensity ratio of TO phonons in crystalline phase to those in disordered phase, were grown at a rate of ∼ 4.0 nm/s after the formation of amorphous incubation layer with a thickness of ∼ 0.1 μm on quartz

  14. Ab initio thermodynamics for the growth of ultra-thin Cu film on a perfect Mg O(001) surface

    International Nuclear Information System (INIS)

    Zhukovskii, Yuri F.; Fuks, David; Kotomin, Eugene A.; Dorfman, Simon

    2005-01-01

    Controlled growth of thin metallic films on oxide substrates is important for numerous micro-and nano electronic applications. Our ab initio study is devoted to the periodic slab simulations for a series of ordered 2a Cu superlattices on the regular Mg O(001) substrate. Submonolayer and monolayer substrate Cu coverages were calculated using the Daft-Gaga method, as implemented into the Crystal-98 code. The results of ab initio calculations have been combined with thermodynamic theory which allows US to predict the growth mode of ultra-thin metal films (spinodal decomposition vs. nucleation-and-growth regime) as a function of the metal coverage and the temperature, and to estimate the metal density in clusters. We show that 3a cluster formation becomes predominant already at low Cu coverages, in agreement with the experiment

  15. The influence of growth temperature on the structural characteristics of YBa2Cu3O7-δ films: a Raman scattering study

    International Nuclear Information System (INIS)

    Belousov, M.V.; Davydov, V.Yu.; Sherman, A.B.

    1993-01-01

    Orientation of YBa 2 Cu 3 O 7-δ films at the surface and at the film-(100) MgO substrate interface for various growth temperatures T s have been studied using Raman scattering. On the film-substrate interface the films were c-oriented for T s >670 degrees C and a-oriented for lower growth temperatures. Films grown at T s approximately=670 degrees C to a thickness >0.2 mu m contained a transition from the c- to the a-orientation near the surface. A possible mechanism for the influence of growth temperature on the YBa 2 Cu 3 O 7-δ film orientation is discussed. (author)

  16. Effect of growth interruption on the crystalline quality and electrical properties of Ga-doped ZnO thin film deposited on quartz substrate by magnetron sputtering

    International Nuclear Information System (INIS)

    Lee, Geun-Hyoung

    2013-01-01

    Ga-doped ZnO(GZO) thin films were deposited on the quartz substrate by magnetron sputtering system with growth interruption technique. As the number of interruptions and interruption time increased, the carrier concentration and Hall mobility in GZO films significantly increased. As a result, the resistivity of GZO films decreased. The optical transmittance of GZO films also increased with the number of interruption and interruption time. The transmittance showed over 90% in visual region. Atomic force microscopy measurement showed that the film surface became smoother with an increase of the number of interruption. In addition, the crystalline quality and electrical properties of GZO films were more improved when the growth interruption was employed with a temperature gradient. - Highlights: • Ga-doped ZnO thin films were deposited with growth interruption technique. • The crystallinity of the films was improved with the number of interruptions. • The crystallinity of the films was improved as the interruption time increased. • The growth interruption with a temperature gradient more improved the film quality

  17. The effect of substrate orientation on the kinetics and thermodynamics of initial oxide-film growth on metals

    Energy Technology Data Exchange (ETDEWEB)

    Reichel, Friederike

    2007-11-19

    This thesis addresses the effect of the parent metal-substrate orientation on the thermodynamics and kinetics of ultra-thin oxide-film growth on bare metals upon their exposure to oxygen gas at low temperatures (up to 650 K). A model description has been developed to predict the thermodynamically stable microstructure of a thin oxide film grown on its bare metal substrate as function of the oxidation conditions and the substrate orientation. For Mg and Ni, the critical oxide-film thickness is less than 1 oxide monolayer and therefore the initial development of an amorphous oxide phase on these metal substrates is unlikely. Finally, for Cu and densely packed Cr and Fe metal surfaces, oxide overgrowth is predicted to proceed by the direct formation and growth of a crystalline oxide phase. Further, polished Al single-crystals with {l_brace}111{r_brace}, {l_brace}100{r_brace} and {l_brace}110{r_brace} surface orientations were introduced in an ultra-high vacuum system for specimen processing and analysis. After surface cleaning and annealing, the bare Al substrates have been oxidized by exposure to pure oxygen gas. During the oxidation, the oxide-film growth kinetics has been established by real-time in-situ spectroscopic ellipsometry. After the oxidation, the oxide-film microstructures were investigated by angle-resolved X-ray photoelectron spectroscopy and low energy electron diffraction. Finally, high-resolution transmission electron microscopic analysis was applied to study the microstructure and morphology of the grown oxide films on an atomic scale. (orig.)

  18. Growth of ordered silver nanoparticles in silica film mesostructured with a triblock copolymer PEO-PPO-PEO

    International Nuclear Information System (INIS)

    Bois, L.; Chassagneux, F.; Parola, S.; Bessueille, F.; Battie, Y.; Destouches, N.; Boukenter, A.; Moncoffre, N.; Toulhoat, N.

    2009-01-01

    Elaboration of mesostructured silica films with a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide, (PEO-PPO-PEO) and controlled growth of silver nanoparticles in the mesostructure are described. The films are characterized using UV-visible optical absorption spectroscopy, TEM, AFM, SEM, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Organized arrays of spherical silver nanoparticles with diameter between 5 and 8 nm have been obtained by NaBH 4 reduction. The size and the repartition of silver nanoparticles are controlled by the film mesostructure. The localization of silver nanoparticles exclusively in the upper-side part of the silica-block copolymer film is evidenced by RBS experiment. On the other hand, by using a thermal method, 40 nm long silver sticks can be obtained, by diffusion and coalescence of spherical particles in the silica-block copolymer layer. In this case, migration of silver particles toward the glass substrate-film interface is shown by the RBS experiment. - Graphical abstract: Growth of silver nanoparticles in a mesostructured block copolymer F127-silica film is performed either by a chemical route involving NaBH 4 reduction or by a thermal method. An array of spherical silver nanoparticles with 10 nm diameter on the upper-side of the mesostructured film or silver sticks long of 40 nm with a preferential orientation are obtained according to the method used. a: TEM image of the Fag5SiNB sample illustrating the silver nanoparticles array obtained by the chemical process; b: HR-TEM image of the Fag20Sid2 sample illustrating the silver nanosticks obtained by the thermal process.

  19. Growth and characterization of indium tin oxide thin films deposited on PET substrates

    International Nuclear Information System (INIS)

    Lee, Jaehyeong; Jung, Hakkee; Lee, Jongin; Lim, Donggun; Yang, Keajoon; Yi, Junsin; Song, Woo-Chang

    2008-01-01

    Transparent and conductive indium tin oxide (ITO) thin films were deposited onto polyethylene terephthalate (PET) by d.c. magnetron sputtering as the front and back electrical contact for applications in flexible displays and optoelectronic devices. In addition, ITO powder was used for sputter target in order to reduce the cost and time of the film formation processes. As the sputtering power and pressure increased, the electrical conductivity of ITO films decreased. The films were increasingly dark gray colored as the sputtering power increased, resulting in the loss of transmittance of the films. When the pressure during deposition was higher, however, the optical transmittance improved at visible region of light. ITO films deposited onto PET have shown similar optical transmittance and electrical resistivity, in comparison with films onto glass substrate. High quality films with resistivity as low as 2.5 x 10 -3 Ω cm and transmittance over 80% have been obtained on to PET substrate by suitably controlling the deposition parameters

  20. Low-cost growth of magnesium doped gallium nitride thin films by sol-gel spin coating method

    Science.gov (United States)

    Amin, N. Mohd; Ng, S. S.

    2018-01-01

    Low-cost sol-gel spin coating growth of magnesium (Mg) doped gallium nitride (GaN) thin films with different concentrations of Mg was reported. The effects of the Mg concentration on the structural, surface morphology, elemental compositions, lattice vibrational, and electrical properties of the deposited films were investigated. X-ray diffraction results show that the Mg-doped samples have wurtzite structure with preferred orientation of GaN(002). The crystallite size decreases and the surface of the films with pits/pores were formed, while the crystalline quality of the films degraded as the Mg concentration increases from 2% to 6. %. All the Raman active phonon modes of the wurtzite GaN were observed while a broad peak attributed to the Mg-related lattice vibrational mode was detected at 669 cm-1. Hall effect results show that the resistivity of the thin films decreases while the hole concentration and hall mobility of thin films increases as the concentration of the Mg increases.

  1. Growth of superconducting MgB2 films by pulsed-laser deposition using a Nd-YAG laser

    International Nuclear Information System (INIS)

    Badica, P; Togano, K; Awaji, S; Watanabe, K

    2006-01-01

    Thin films of MgB 2 on r-cut Al 2 O 3 substrates have been grown by pulsed-laser deposition (PLD) using a Nd-YAG laser (fourth harmonic-266 nm) instead of the popular KrF excimer laser. The growth window to obtain superconducting films is laser energy 350-450 mJ and vacuum pressure with Ar-buffer gas of 1-8/10 Pa (initial background vacuum 0.5-1 x 10 -3 Pa). Films were deposited at room temperature and post-annealed in situ and ex situ at temperatures of 500-780 0 C and up to 1 h. Films are randomly oriented with maximum critical temperature (offset of resistive transition) of 27 K. SEM/TEM/EDS investigations show that they are mainly composed of small sphere-like particles (≤20 nm), and contain oxygen and some carbon, uniformly distributed in the flat matrix, but the amount of Mg and/or oxygen is higher in the aggregates-droplets (100-1000 nm) observed on the surface of the film's matrix. Some aspects of the processing control and dependences on film characteristics are discussed. The technique is promising for future development of coated conductors

  2. The effect of total body irradiation and bone marrow transplantation during childhood and adolescence on growth and endocrine function

    International Nuclear Information System (INIS)

    Leiper, A.D.; Stanhope, R.; Lau, T.; Grant, D.B.; Blacklock, H.; Chessells, J.M.; Plowman, P.N.

    1987-01-01

    Seventeen children with acute leukaemia and myeloproliferative disorders were investigated for growth and endocrine dysfunction. All had undergone bone marrow transplantation prepared with cyclophosphamide and single fraction total body irradiation (900-1000 cGy) between 1.5 and 3.8 (mean 2.2) years previously. The majority exhibited growth failure, of multiple aetiology. Ten patients, of whom eight had had previous prophylactic cranial irradiation, had evidence of growth hormone deficiency based on reduced growth hormone reponse to insulin induced hypoglycaemia. Three had evidence of hypothalamic damage. Gonadal failure was common. All four girls of adolescent age (10.6-14.1 years) had ovarian failure requiring sex steroid replacement. Of eight boys of adolescent age (12.3-18.3 years), two had testicular failure requiring sex steroid supplements. Both had had previous testicular irradiation. Five others had compensated gonadal failure; one had normal Leydig cell function. Abnormalities of the TSH response to TRH occurred in 10 patients but only three had overt hypothyroidism. Unlike growth hormone deficiency, gonadal and thyroid dysfunction showed no correlation with previous cranial radiotherapy. (author)

  3. Influence of the growth parameters on TiO2 thin films deposited using the MOCVD method

    Directory of Open Access Journals (Sweden)

    Bernardi M. I. B.

    2002-01-01

    Full Text Available In this work we report the synthesis of TiO2 thin films by the Organometallic Chemical Vapor Deposition (MOCVD method. The influence of deposition parameters used during the growth in the obtained structural characteristics was studied. Different temperatures of the organometallic bath, deposition time, temperature and type of the substrate were combined. Using Scanning Electron Microscopy associated to Electron Dispersive X-Ray Spectroscopy, Atomic Force Microscopy and X-ray Diffraction, the strong influence of these parameters in the thin films final microstructure was verified.