WorldWideScience

Sample records for net deposit growth

  1. [Zr(NEtMe)2(guan-NEtMe)2] as a novel ALD precursor: ZrO2 film growth and mechanistic studies

    NARCIS (Netherlands)

    Blanquart, T.; Niinistö, J.; Aslam, N.; Banerjee, M.; Tomczak, Y.; Gavagnin, M.; Longo, V.; Puukilainen, E.; Wanzenboeck, H.D.; Kessels, W.M.M.; Devi, A.; Hoffmann-Eifert, S.; Ritala, M.; Leskelä, M.

    2013-01-01

    [Zr(NEtMe)2(guan-NEtMe2)2], a recently developed compound, was investigated as a novel precursor for the atomic layer deposition (ALD) of ZrO2. With water as the oxygen source, the growth rate remained constant over a wide temperature range, whereas with ozone the growth rate increased steadily with

  2. Net atmospheric mercury deposition to Svalbard: Estimates from lacustrine sediments

    Science.gov (United States)

    Drevnick, Paul E.; Yang, Handong; Lamborg, Carl H.; Rose, Neil L.

    2012-11-01

    In this study we used lake sediments, which faithfully record Hg inputs, to derive estimates of net atmospheric Hg deposition to Svalbard, Norwegian Arctic. With the exception of one site affected by local pollution, the study lakes show twofold to fivefold increases in sedimentary Hg accumulation since 1850, likely due to long-range atmospheric transport and deposition of anthropogenic Hg. Sedimentary Hg accumulation in these lakes is a linear function of the ratio of catchment area to lake area, and we used this relationship to model net atmospheric Hg flux: preindustrial and modern estimates are 2.5 ± 3.3 μg m-2 y-1 and 7.0 ± 3.0 μg m-2 y-1, respectively. The modern estimate, by comparison with data for Hg wet deposition, indicates that atmospheric mercury depletion events (AMDEs) or other dry deposition processes contribute approximately half (range 0-70%) of the net flux. Hg from AMDEs may be moving in significant quantities into aquatic ecosystems, where it is a concern because of contamination of aquatic food webs.

  3. DEPOSIT GUARANTEE SCHEMES JOIN FINANCIAL SAFETY-NET

    Directory of Open Access Journals (Sweden)

    Eugen Dijmarescu

    2011-03-01

    Full Text Available Deposit Guarantee Schemes (DGS become more visible under the current conditions of the world financial markets. If those have played in the past a rather discreet role for social stability through the function of pay box following a bank failure, the recent crisis put them in a new light, once the guarantee ceiling for eligible deposits grew in order to make for the accumulation of wealth worldwide and the increased risk incurred by the leverage of banking operations. Consequently, the resources accumulated by the DGS from the member banks and their proper management make possible their involvement in pre-emptive actions aimed to avoid bankruptcies via special administration and purchase of assets and assumption of liabilities. These new attributes give DGS a role in the mechanism of financial safety-net, along the supervisors of the market. Hence, an increased preoccupation for applied corporate governance has developed and Core Principles for Effective Deposit Insurance Systems have been adopted by the Basel Committee on Banking Supervision together with International Association of Deposit Insurers. Concurrently, the EU Commission has put forward a process for reviewing the Directives 94/39 and 09/14 EC, in order to make the European DGS more prepared to deal with above mentioned issues and bestow increased confidence upon depositors.

  4. Net energy analysis in a Ramsey–Hotelling growth model

    International Nuclear Information System (INIS)

    Macías, Arturo; Matilla-García, Mariano

    2015-01-01

    This article presents a dynamic growth model with energy as an input in the production function. The available stock of energy resources is ordered by a quality parameter based on energy accounting: the “Energy Return on Energy Invested” (EROI). In our knowledge this is the first paper where EROI fits in a neoclassical growth model (with individual utility maximization and market equilibrium), establishing the economic use of “net energy analysis” on a firmer theoretical ground. All necessary concepts to link neoclassical economics and EROI are discussed before their use in the model, and a comparative static analysis of the steady states of a simplified version of the model is presented. - Highlights: • A neoclassical growth model with EROI (“Energy Return on Energy Invested”) is shown • All concepts linking neoclassical economics and net energy analysis are discussed • Any EROI decline can be compensated increasing gross activity in the energy sector. • The economic impact of EROI depends on some non-energy cost in the energy sector. • Comparative steady-state statics for different EROI levels is performed and discussed. • Policy implications are suggested.

  5. Deposition and growth of domains in one dimension

    Science.gov (United States)

    Rodgers, G. J.; Tavassoli, Z.

    1998-09-01

    A model of deposition and growth in one dimension is studied in which finite sized domains are deposited by the random sequential adsorption process. The domains then grow with a time dependent growth rate. When the initial deposited domains are monomers and dimers the coverage is found exactly for a number of different growth rates. A continuum version of this model is also considered.

  6. On bar growth and decay during interannual net offshore migration

    NARCIS (Netherlands)

    Walstra, D.J.R.; Reniers, A.J.H.M.; Ranasinghe, R.; Roelvink, J.A.; Ruessink, B.G.

    2012-01-01

    Multiple bar systems often show a cyclic net offshore directed migration with return periods on the order of years. Generally, a bar is generated near the shoreline, grows in height and width, while migrating offshore before finally decaying at the seaward limit of the surf zone. Based on a

  7. Contribution of foliar leaching and dry deposition to sulfate in net throughfall below deciduous trees

    International Nuclear Information System (INIS)

    Garten, C.T. Jr.; Bondietti, E.A.; Lomax, R.D.

    1988-01-01

    Experiments were conducted at Walker Branch Watershed, Tennessee in 1986 with radioactive 35 S to quantify the contribution of foliar leaching and dry deposition to sulfate (SO 4 2- ) in net throughfall (NTF). Two red maple (Acer rubrum) and two yellow poplar (Liriodendron tulipifera) trees (12-15 m tall) were radiolabeled by stem well injection. Total S and 35 S were measured in leaves; 35 S and SO 4 2- were measured in throughfall (THF). The contribution of foliar leaching to SO 4 2- in NTF, THF minus incident precipitation, was estimated by isotope dilution of 35 S in NTF arising from nonradioactive S in dry deposition. The per cent contribution of foliar leaching to SO 4 2- in NTF was greatest during the week following isotope labeling and during the period of autumn leaf fall. During the growing season, foliar leaching accounted for 80% of the SO 4 2- in NTF beneath the study trees. Dry deposition of S to these tree species can be reasonably approximated during summer from the measurement of SO 4 2- flux in NTF. (author)

  8. Photosynthetic behavior, growth and essential oil production of Melissa officinalis L. cultivated under colored shade nets

    OpenAIRE

    Graziele C Oliveira; Willyam L Vieira; Suzana C Bertolli; Ana Claudia Pacheco

    2016-01-01

    The modulation of light is of importance during cultivation of medicinal plants to obtain desirable morphological and physiological changes associated with the maximum production of active principles. This study aimed to evaluate the effect of the light spectrum transmitted by colored shade nets on growth, essential oil production and photosynthetic behavior in plants of lemon balm (Melissa officinalis L.) Plants were cultivated in pots for 4-mo under black, red, and blue nets with 50% shadin...

  9. Initial growth of Bauhinia variegata trees under different colored shade nets and light conditions

    Directory of Open Access Journals (Sweden)

    Renata Bachin Mazzini-Guedes

    2014-12-01

    Full Text Available Bauhinia variegata and B. variegata var. candida, commonly known as orchid trees, are small sized trees widely used for urban forestry and landscaping. Adult plants grow under full sun; in Brazil, however, seedlings are generally cultivated in commercial nurseries under natural half-shading. The objective of this study was to evaluate the influence of different colored shade nets and light conditions on the initial growth of B. variegata and B. variegata var. candida. The influence of six light conditions (red net with 50% shading; blue net with 50% shading; black net with 70% shading; black net with 50% shading; black net with 30% shading; and full sun on the initial growth of B. variegata and B. variegata var. candida were evaluated along 160 days, and growth relationships were calculated. Seedlings showed more efficiency on the use of photoassimilated compounds when grown under full sun. Such condition is the most appropriate for seedling production of B. variegata and B. variegata var. candida, contradicting what has been performed in practice.

  10. How deposition parameters control growth dynamics of nc-Si deposited by hot-wire chemical vapor deposition

    International Nuclear Information System (INIS)

    Moutinho, H.R.; To, B.; Jiang, C.-S.; Xu, Y.; Nelson, B.P.; Teplin, C.W.; Jones, K.M.; Perkins, J.; Al-Jassim, M.M.

    2006-01-01

    We studied the growth of silicon films deposited by hot-wire chemical vapor deposition under different values of filament current, substrate temperature, and hydrogen dilution ratio. The physical and electrical properties of the films were studied by Raman spectroscopy, x-ray diffraction, atomic force microscopy, conductive-atomic force microscopy, and transmission electron microscopy. There is an interdependence of the growth parameters, and films grown with different parameters can have similar structures. We discuss why this interdependence occurs and how it influences the properties of the deposited films, as well as the deposition rate. In general, the films have a complex structure, with a mixture of amorphous (220)-oriented crystalline and nanocrystalline phases present in most cases. The amount of each phase can be controlled by the variation of one or more of the growth parameters at a time

  11. Carbon nanotube forests growth using catalysts from atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bingan; Zhang, Can; Esconjauregui, Santiago; Xie, Rongsi; Zhong, Guofang; Robertson, John [Department of Engineering, University of Cambridge, Cambridge CB3 0FA (United Kingdom); Bhardwaj, Sunil [Istituto Officina dei Materiali-CNR Laboratorio TASC, s.s. 14, km 163.4, I-34012 Trieste (Italy); Sincrotone Trieste S.C.p.A., s.s. 14, km 163.4, I-34149 Trieste (Italy); Cepek, Cinzia [Istituto Officina dei Materiali-CNR Laboratorio TASC, s.s. 14, km 163.4, I-34012 Trieste (Italy)

    2014-04-14

    We have grown carbon nanotubes using Fe and Ni catalyst films deposited by atomic layer deposition. Both metals lead to catalytically active nanoparticles for growing vertically aligned nanotube forests or carbon fibres, depending on the growth conditions and whether the substrate is alumina or silica. The resulting nanotubes have narrow diameter and wall number distributions that are as narrow as those grown from sputtered catalysts. The state of the catalyst is studied by in-situ and ex-situ X-ray photoemission spectroscopy. We demonstrate multi-directional nanotube growth on a porous alumina foam coated with Fe prepared by atomic layer deposition. This deposition technique can be useful for nanotube applications in microelectronics, filter technology, and energy storage.

  12. The in situ growth of 3D net-like CNTs on C fiber

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Junfeng, E-mail: majunfeng01@sina.cn; Lan, Xuena; Niu, Bingbing; Fan, Dongxiao

    2017-05-01

    Carbon nanotubes (CNTs) with 3 dimensional net-like structure were perfectly grown on C fiber at ambient temperature and pressure using a modified electrochemical process, and their composition and morphology were characterized by Raman spectroscopy, Energy dispersive spectroscopy (EDS), High resolution transmission electron microscopy (HRTEM), and Scanning electron microscopy (SEM), respectively. This paper also reported the influence of applied voltage and reaction time on the formation and growth of CNTs, and proposed a possible growth mechanism. - Highlights: • CNTs with 3D net-like structure were grown on C fiber by an “electrochemical” route. • The formation and growth of CNTs relied on applied voltage and reaction time. • A possible growth mechanism was proposed.

  13. 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.

  14. The effect of irradiance on long-term skeletal growth and net photosynthesis in Galaxea fascicularis under four light conditions.

    NARCIS (Netherlands)

    Schutter, M.; Velthoven, van B.; Janse, M.; Osinga, R.; Janssen, M.G.J.; Wijffels, R.H.; Verreth, J.A.J.

    2008-01-01

    The relation between irradiance, skeletal growth and net photosynthesis was studied for the scleractinian coral Galaxea fascicularis to provide experimental evidence for mediation of light-enhanced calcification through photosynthesis. The hypothesis was tested that skeletal growth and

  15. Simulating the initial growth of a deposit from colloidal suspensions

    International Nuclear Information System (INIS)

    Oliveira, T J; Aarão Reis, F D A

    2014-01-01

    We study the short time properties of a two-dimensional film growth model in which incident particles execute advective-diffusive motion with a vertical step followed by D horizontal steps. The model represents some features of the deposition of anisotropic colloidal particles of the experiment of Yunker et al (2013 Phys. Rev. Lett. 110 035501), in which wandering particles are attracted to particle-rich regions in the deposit. Height profiles changing from rough to columnar structure are observed as D increases from 0 (ballistic deposition) to 8, with striking similarity to the experimental ones. The effective growth exponents match the experimental estimates and the scaling of those exponents on D shows a remarkable effect of the range of the particle-deposit interaction. The nearly ellipsoidal shape of colloidal particles is represented for the calculation of roughness exponents in conditions that parallel the experimental ones, giving a range of estimates that also includes the experimental values. The effective dynamic exponents calculated from the autocorrelation function are shown to be suitable to decide between a true dynamic scaling or transient behavior, particularly because the latter leads to deviations in an exponent relation. These results are consistent with arguments on short time unstable (columnar) growth of Nicoli et al (2013 Phys. Rev. Lett. 111 209601), indicating that critical quenched KPZ dynamics does not explain that colloidal particle deposition problem. (paper)

  16. 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.

  17. Validation of the periodicity of growth increment deposition in ...

    African Journals Online (AJOL)

    Validation of the periodicity of growth increment deposition in otoliths from the larval and early juvenile stages of two cyprinids from the Orange–Vaal river ... Linear regression models were fitted to the known age post-fertilisation and the age estimated using increment counts to test the correspondence between the two for ...

  18. 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.

  19. Vertically aligned carbon nanotube growth by pulsed laser deposition and thermal chemical vapor deposition methods

    International Nuclear Information System (INIS)

    Sohn, Jung Inn; Nam, Chunghee; Lee, Seonghoon

    2002-01-01

    We have grown vertically aligned carbon nanotubes on the various substrates such as a planar p-type Si(1 0 0) wafer, porous Si wafer, SiO 2 , Si 3 N 4 , Al 2 O 3 , and Cr by thermal chemical vapor deposition (CVD) at 800 deg.C, using C 2 H 2 gas as a carbon source and Fe catalyst films deposited by a pulsed laser on the substrates. The Fe films were deposited for 5 min by pulsed laser deposition (PLD). The advantage of Fe deposition by PLD over other deposition methods lies in the superior adhesion of Fe to a Si substrate due to high kinetic energies of the generated Fe species. Scanning electron microscopy (SEM) images show that vertically well-aligned carbon nanotubes are grown on Fe nanoparticles formed from the thermal annealing of the Fe film deposited by PLD on the various substrates. Atomic force microscopy (AFM) images show that the Fe film annealed at 800 deg.C is broken to Fe nanoparticles of 10-50 nm in size. We show that the appropriate density of Fe nanoparticles formed from the thermal annealing of the film deposited by PLD is crucial in growing vertically aligned carbon nanotubes. Using a PLD and a lift-off method, we developed the selective growth of carbon nanotubes on a patterned Fe-coated Si substrate

  20. Photosynthetic behavior, growth and essential oil production of Melissa officinalis L. cultivated under colored shade nets

    Directory of Open Access Journals (Sweden)

    Graziele C Oliveira

    2016-03-01

    Full Text Available The modulation of light is of importance during cultivation of medicinal plants to obtain desirable morphological and physiological changes associated with the maximum production of active principles. This study aimed to evaluate the effect of the light spectrum transmitted by colored shade nets on growth, essential oil production and photosynthetic behavior in plants of lemon balm (Melissa officinalis L. Plants were cultivated in pots for 4-mo under black, red, and blue nets with 50% shading, and full sunlight exposure. Biometric and anatomical variables, essential oil yield, global solar radiation, photon flux density, chlorophyll content, and gas exchange parameters were measured in M. officinalis leaves. The results showed that despite being considered a partial shade plant, this species is able to adapt to full sunlight conditions without increasing biomass production. The spectral changes provided by colored shade nets did not caused any noticeable change in leaf anatomy of M. officinalis. However, the use of blue net resulted in increments of 116% in plant height, 168% in leaf area, 42% in chlorophyll content and 30% in yield of essential oil in lemon balm plants. These plant's qualities make the use of blue net a cultivation practice suitable for commercial use.

  1. An investigation on different factors influencing growth of banking deposits

    Directory of Open Access Journals (Sweden)

    Zahra Houshmand Neghabi

    2013-01-01

    Full Text Available Banking deposit is the primary source of contributing to economy and it is important to understand what factors influence such deposits. In this paper, we present an empirical study to find the relationship between banking deposit and other important factors such as capital market, money market, commodity market, foreign exchange rates such as US dollar and Euro exchange rates to local currency (Rials. We gather the data over the period of 2010-2012 and using ordinary least square technique study different hypotheses. All t-student values are statistically meaningful when the level of significance is ten percent and some of the parameters are even meaningful when the level of significance is five percent. The results indicate that the rate of bank deposit is negatively associated with commodity market growth rate (-.001995, US dollar exchange rate (-0.004167, banking industry growth rate (-0.278826 and moving average (-0.940418. In addition, dependent variable is positively associated with Euro exchange growth rate (0.005676.

  2. Deposit growth and property development in coal-fired furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, L. [Sandia National Lab., Livermore, CA (United States)

    1995-11-01

    The objectives of this research project are: (1) to provide a self-consistent database of simultaneously measured, time-resolved ash deposit properties in well-controlled and well-defined environments and (2) to provide analytical expressions that relate deposit composition and structure to deposit properties of immediate relevance to PETC`s Combustion 2000 program. This project is distinguished from related work being done elsewhere by: (1) the development and deployment of in-situ diagnostics to monitor deposit properties, including heat transfer coefficients, porosity, emissivity, tenacity, strength, density, and viscosity; (2) the time resolution of such properties during deposit growth; (3) simultaneous measurement of structural and composition properties; (4) development of algorithms from a self-consistent, simultaneously measured database that includes the interdependence of properties; and (5) application of the results to technologically relevant environments such as those being planned under Combustion 2000 program. Work completed during FY94 emphasized diagnostic development. During FY95, this development work will be completed and we will emphasize application of the diagnostics to meet the other project objectives. Included in this work are the development and application of two in-situ, real-time diagnostic systems for monitoring the properties of inorganic materials on Heat transfer surfaces and in the gas-phase during controlled combustion of selected coal samples in Sandia`s Multifuel Combustor (MFC). Also, several diagnostics are being incorporated into the MFC that will eventually be used to characterize ash deposit properties.

  3. Boron Application Improves Growth, Yield and Net Economic Return of Rice

    Directory of Open Access Journals (Sweden)

    Mubshar HUSSAIN

    2012-09-01

    Full Text Available A field trial was conducted to evaluate the role of boron (B application at different growth stages in improving the growth, yield and net economic return of rice at farmer's fields during summer season, 2009. Boron was soil applied (1.5 kg/hm2 at the transplanting, tillering, flowering and grain formation stages of rice; foliar applied (1.5% B solution at the tillering, flowering and grain formation stages of rice, and dipped seedling roots in 1.5% B solution before transplanting; while control plots did not apply any B. Boron application (except dipping of seedling roots in B solution, which caused toxicity and reduced the number of tillers and straw yield than control substantially improved the rice growth and yield. However, soil application was better in improving the number of grains per panicle, 1000-grain weight, grain yield, harvest index, net economic income and ratio of benefit to cost compared with the rest of treatments. Overall, for improving rice performance and maximizing the net economic returns, B might be applied as soil application at flowering.

  4. Molecular dynamics simulation of gold cluster growth during sputter deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, J. W., E-mail: abraham@theo-physik.uni-kiel.de; Bonitz, M., E-mail: bonitz@theo-physik.uni-kiel.de [Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, D-24098 Kiel (Germany); Strunskus, T.; Faupel, F. [Institut für Materialwissenschaft, Lehrstuhl für Materialverbunde, Christian-Albrechts-Universität zu Kiel, Kaiserstraße 2, D-24143 Kiel (Germany)

    2016-05-14

    We present a molecular dynamics simulation scheme that we apply to study the time evolution of the self-organized growth process of metal cluster assemblies formed by sputter-deposited gold atoms on a planar surface. The simulation model incorporates the characteristics of the plasma-assisted deposition process and allows for an investigation over a wide range of deposition parameters. It is used to obtain data for the cluster properties which can directly be compared with recently published experimental data for gold on polystyrene [M. Schwartzkopf et al., ACS Appl. Mater. Interfaces 7, 13547 (2015)]. While good agreement is found between the two, the simulations additionally provide valuable time-dependent real-space data of the surface morphology, some of whose details are hidden in the reciprocal-space scattering images that were used for the experimental analysis.

  5. 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.

  6. Chemical vapor deposition of ZrO{sub 2} thin films using Zr(NEt{sub 2}){sub 4} as precursor

    Energy Technology Data Exchange (ETDEWEB)

    Bastianini, A. [CNR, Padova (Italy). Ist. di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati; Battiston, G.A. [CNR, Padova (Italy). Ist. di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati; Gerbasi, R. [CNR, Padova (Italy). Ist. di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati; Porchia, M. [CNR, Padova (Italy). Ist. di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati; Daolio, S. [CNR, Padova (Italy). Ist. di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati]|[CNR, Ist. di Polarografia ed Elettrochimica Preparativa, Padova (Italy)

    1995-06-01

    By using tetrakis(diethylamido) zirconium [Zr(NEt{sub 2}){sub 4}], excellent quality ZrO{sub 2} thin films were deposited with high growth rates on alumina and glass substrates by chemical vapor deposition. The depositions were carried out in a hot wall reactor at reduced pressure (200 Pa) in the temperature range 500-580 C and in the presence of oxygen. The as-grown films are colourless, smooth and well-adherent to the substrates. SIMS analysis evidenced pure ZrO{sub 2} with a slight superficial contamination of hydrocarbons and nitrogen. The films have a tapered polycrystalline columnar structure well visible in SEM micrographs. From X-ray diffraction analysis, the monoclinic phase resulted as the major phase together with a small variable amount of tetragonal zirconia. Under 550 C the as-grown films resulted highly textured and were dominated by the (020) orientation. The films were annealed in the range 600-1000 C and the effect of annealing on the texture and on the phase and dimensions of the crystallites have been studied. (orig.).

  7. Dust deposition effects on growth and physiology of the endangered Astragalus jaegerianus (Fabaceae)

    Science.gov (United States)

    Wijayratne, Upekala C.; Scoles-Sciulla, Sara J.; Defalco, Lesley A.

    2009-01-01

    Human expansion into the Mojave Desert is a significant threat to rare desert plants. While immediate habitat loss is often the greatest concern, rare plants situated near areas where soil surfaces experience frequent disturbance may be indirectly impacted when fine particulate dust accumulates on leaf surfaces. Remaining populations of the federally listed Astragalus jaegerianus (Lane Mountain milkvetch) occur on land open to expanding military activities and on adjacent public land with increasing recreational use. This study was initiated to determine whether dust accumulation could decrease the vigor and fitness of A. jaegerianus through reduced growth. Beginning in early May 2004, plants located on Bureau of Land Management (BLM) land were dusted bimonthly at canopy-level dust concentrations ranging from 0 to 32 g/m2, and physiology and growth were monitored until late June when plants senesced. The maximum experimental dust level simulates dust concentrations of Mojave Desert perennials neighboring military activities at a nearby army training center. Average shoot growth declined with increasing dust accumulation, but seasonal net photosynthesis increased. Further investigation of plants grown in a greenhouse supported similar trends. This pattern of greater net photosynthesis with increasing dust accumulation may be explained by higher leaf temperatures of dusted individuals. Ambient dust deposition measured in traps near field plants (May 2004–July 2004) ranged from 0.04–0.17 g/m2/ d, which was well below the lowest level of dust on experimental plants (3.95 g/m2/d). With this low level of ambient deposition, we expect that A. jaegerianus plants in this population were not greatly affected by the dust they receive at the level of recreational use during the study.

  8. Chemical vapor deposition growth of two-dimensional heterojunctions

    Science.gov (United States)

    Cui, Yu; Li, Bo; Li, JingBo; Wei, ZhongMing

    2018-01-01

    The properties of two-dimensional (2D) layered materials with atom-smooth surface and special interlayer van der Waals coupling are different from those of traditional materials. Due to the absence of dangling bonds from the clean surface of 2D layered materials, the lattice mismatch influences slightly on the growth of 2D heterojunctions, thus providing a flexible design strategy. 2D heterojunctions have attracted extensive attention because of their excellent performance in optoelectronics, spintronics, and valleytronics. The transfer method was utilized for the fabrication of 2D heterojunctions during the early stage of fundamental research on these materials. This method, however, has limited practical applications. Therefore, chemical vapor deposition (CVD) method was recently developed and applied for the preparation of 2D heterojunctions. The CVD method is a naturally down-top growth strategy that yields 2D heterojunctions with sharp interfaces. Moreover, this method effectively reduces the introduction of contaminants to the fabricated heterojunctions. Nevertheless, the CVD-growth method is sensitive to variations in growth conditions. In this review article, we attempt to provide a comprehensive overview of the influence of growth conditions on the fabrication of 2D heterojunctions through the direct CVD method. We believe that elucidating the effects of growth conditions on the CVD method is necessary to help control and improve the efficiency of the large-scale fabrication of 2D heterojunctions for future applications in integrated circuits.

  9. Generation time, net reproductive rate, and growth in stage-age-structured populations

    DEFF Research Database (Denmark)

    Steiner, Uli; Tuljapurkar, Shripad; Coulson, Tim

    2014-01-01

    examples to show how reproductive timing Tc and level R0 are shaped by stage dynamics (individual trait changes), selection on the trait, and parent-offspring phenotypic correlation. We also show how population structure can affect dispersion in reproduction among ages and stages. These macroscopic...... to age-structured populations. Here we generalize this result to populations structured by stage and age by providing a new, unique measure of reproductive timing (Tc) that, along with net reproductive rate (R0), has a direct mathematical relationship to and approximates growth rate (r). We use simple...

  10. Changes in conifer and deciduous forest foliar and forest floor chemistry and basal area tree growth across a nitrogen (N) deposition gradient in the northeastern US

    International Nuclear Information System (INIS)

    Boggs, Johnny L.; McNulty, Steven G.; Pardo, Linda H.

    2007-01-01

    We evaluated foliar and forest floor chemistry across a gradient of N deposition in the Northeast at 11 red spruce (Picea rubens Sarg.) sites in 1987/1988 and foliar and forest floor chemistry and basal area growth at six paired spruce and deciduous sites in 1999. The six red spruce plots were a subset of the original 1987/1988 spruce sites. In 1999, we observed a significant correlation between mean growing season temperature and red spruce basal area growth. Red spruce and deciduous foliar %N correlated significantly with N deposition. Although N deposition has not changed significantly from 1987/1988 to 1999, net nitrification potential decreased significantly at Whiteface. This decrease in net potential nitrification is not consistent with the N saturation hypothesis and suggests that non-N deposition controls, such as climatic factors and immobilization of down dead wood, might have limited N cycling. - Data from the 1999 remeasurement of the red spruce forests suggest that N deposition, to some extent, is continuing to influence red spruce across the northeastern US as illustrated by a significant correlation between N deposition and red spruce foliar %N. Our data also suggest that the decrease in forest floor %N and net nitrification potential across sites from 1987 to 1999 may be due to factors other than N deposition, such as climatic factors and N immobilization in fine woody material (<5 cm diameter)

  11. Considerations on heat deposition by eddy currents in the cold structure of INTOR/NET

    International Nuclear Information System (INIS)

    Bloemer, B.; Farfaletti-Casali, F.

    1983-01-01

    In a tokamak like INTOR/NET large eddy currents can be induced in all conductive parts of the reactor mainly by the time-varying poloidal fields. In order to minimize the refrigeration power the heat load generated by eddy currents has to be kept as small as possibly especially in the large toroidal- and poloidal-field coil support structures, which are conductive and at temperatures of less than 4.2 K. A method is described identifying the parts of the structure wherein most of the heat generated by eddy currents is dissipated. By dividing a given configuration into reasonable segments of appointed geometry eddy current losses can easily be calculated. Compared to sophisticated computer programs this procedure is simple but of sufficient accuracy for a lot of applications and it delivers prompt results. The method is applied to the TF coil support structure of a specific design of INTOR/NET. As the results show that the heat load is intolerably high a modified design is proposed. (author)

  12. Effects of ozone on growth, net photosynthesis and yield of two African varieties of Vigna unguiculata.

    Science.gov (United States)

    Tetteh, Rashied; Yamaguchi, Masahiro; Wada, Yoshiharu; Funada, Ryo; Izuta, Takeshi

    2015-01-01

    To assess the effects of O(3)on growth, net photosynthesis and yield of two African varieties of cowpea(Vigna unguiculata L.), Blackeye and Asontem were exposed as potted plants to air that was either filtered to remove O(3) (FA), non-filtered air (NF), non-filtered with added O3 of approximately 50 nL L(-1) (ppb) from 11:00 to 16:00 (NF + O(3)) for 88 days in open-top chambers. The mean O(3) concentration (11:00-16:00) during the exposure period had a range from 16 ppb in the FA treatment to 118 ppb in the NF + O(3) treatment. Net photosynthetic rate and leaf area per plant were significantly reduced by exposure to O(3), reducing the growth of both varieties. Exposure to O(3) significantly reduced the 100-seed weight and number of seeds per pod. As a result, cowpea yield was significantly reduced by long-term exposure to O(3), with no difference in sensitivity between the varieties.

  13. Growth fluctuations in a class of deposition models

    CERN Document Server

    Balazs, M

    2003-01-01

    We compute the growth fluctuations in equilibrium of a wide class of deposition models. These models also serve as general frame to several nearest-neighbor particle jump processes, e.g. the simple exclusion or the zero range process, where our result turns to current fluctuations of the particles. We use martingale technique and coupling methods to show that, rescaled by time, the variance of the growth as seen by a deterministic moving observer has the form |V-C|*D, where V and C is the speed of the observer and the second class particle, respectively, and D is a constant connected to the equilibrium distribution of the model. Our main result is a generalization of Ferrari and Fontes' result for simple exclusion process. Law of large numbers and central limit theorem are also proven. We need some properties of the motion of the second class particle, which are known for simple exclusion and are partly known for zero range processes, and which are proven here for! a type of deposition models and also for a t...

  14. 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

  15. Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)

    Science.gov (United States)

    Manríquez, Patricio H.; Jara, María Elisa; Mardones, María Loreto; Navarro, Jorge M.; Torres, Rodrigo; Lardies, Marcos A.; Vargas, Cristian A.; Duarte, Cristian; Widdicombe, Stephen; Salisbury, Joseph; Lagos, Nelson A.

    2013-01-01

    Background Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. Methodology/Principal Findings The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. Conclusions and Significance These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature. PMID:23844231

  16. Ocean acidification disrupts prey responses to predator cues but not net prey shell growth in Concholepas concholepas (loco.

    Directory of Open Access Journals (Sweden)

    Patricio H Manríquez

    Full Text Available BACKGROUND: Most research on Ocean Acidification (OA has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. METHODOLOGY/PRINCIPAL FINDINGS: The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE (716 ± 12 and 1036 ± 14 µatm CO2 compared to those reared at concentrations equivalent to those presently found in the surface ocean (388 ± 8 µatm CO2. When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. CONCLUSIONS AND SIGNIFICANCE: These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.

  17. Ocean acidification disrupts prey responses to predator cues but not net prey shell growth in Concholepas concholepas (loco).

    Science.gov (United States)

    Manríquez, Patricio H; Jara, María Elisa; Mardones, María Loreto; Navarro, Jorge M; Torres, Rodrigo; Lardies, Marcos A; Vargas, Cristian A; Duarte, Cristian; Widdicombe, Stephen; Salisbury, Joseph; Lagos, Nelson A

    2013-01-01

    Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716 ± 12 and 1036 ± 14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388 ± 8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.

  18. Development and evaluation of a long-term deposit probe for on-line monitoring of deposit growth

    Energy Technology Data Exchange (ETDEWEB)

    Brink, Anders; Lauren, Tor; Yrjas, Patrik; Hupa, Mikko [Process Chemistry Centre, Aabo Akademi University, Biskopsgatan 8, FI-20540 Turku (Finland); Friesenbichler, Joachim [Institute for Resource Efficient and Sustainable Systems, Technical University Graz Inffeldg. 21b, A-8010 Graz (Austria)

    2007-12-15

    A newly designed air-cooled probe for on-line monitoring of deposition growth has been tested in a boiler firing three woody fuels. Thermocouples are mounted on both sides of the tube wall enabling measurements of the heat flux through the probe wall. Knowing the heat flux through the probe wall, it is possible to measure the additional heat transfer resistance caused by the deposit and to estimate the properties of the deposit. Calculating the deposit thickness using the collected temperature data indicated the thinnest deposit when wood was fired, followed by bark and waste wood. The calculated deposit thickness was larger than those found when analysing the deposit thickness after the probe had been removed. Nevertheless, the ranking of fuels by deposit build-up rate was the same. (author)

  19. Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration

    Science.gov (United States)

    Chang, Sung-Jin; Hyun, Moon Seop; Myung, Sung; Kang, Min-A.; Yoo, Jung Ho; Lee, Kyoung G.; Choi, Bong Gill; Cho, Youngji; Lee, Gaehang; Park, Tae Jung

    2016-03-01

    Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties.

  20. Nitrogen and sulphur deposition and the growth of Sphagnum fuscum in bogs of the Athabasca Oil Sands Region, Alberta

    Directory of Open Access Journals (Sweden)

    Melanie A. VILE

    2010-08-01

    Full Text Available One of the consequences of ongoing development of the oil sands reserve in the Athabasca Oil Sands Region (AOSR near Fort McMurray, Alberta, Canada (56° 39' N, 111° 13' W is an increase in emissions of nitrogen (N and sulphur (S, with an attendant increases in regional atmospheric N and S deposition. Regional land cover across northeastern Alberta is a mixture of Boreal Mixedwood, Boreal Highlands, and Subarctic areas. Peatlands occupy between 22 and 66% of these natural regions, and the land cover of bogs varies between 6.7% in the Mixedwood Region to 46% in the Subarctic Region. Ombrotrophic bog ecosystems may be especially sensitive to atmospheric deposition of N and S. Across 10 ombrotrophic bog sites in the AOSR over four years (2005– 2008, we found no evidence of elevated deposition of NH4 +-N, NO3 –-N, total inorganic nitrogen (TIN; NH4 +-N plus NO3 –-N, or SO4 2–-S, with values measured using ion exchange resin collectors averaging 0.61 ± 04, 0.20 ± 0.01, 0.81 ± 0.04, and 1.14 ± 0.06 kg ha–1 y–1, respectively. Vertical growth and net primary production of Sphagnum fuscum, an indicator of elevated deposition, did not differ consistently across sites, averaging 11.8 ± 0.2 mm y–1 and 234 ± 3.3 g m–2 y–1, respectively, over the four years. Neither vertical growth nor net primary production of S. fuscum was correlated with growing season atmospheric N or S deposition. Our data provide a valuable benchmark of background values for monitoring purposes in anticipation of increasing N and S deposition over a broader geographic region within the AOSR.

  1. Size and growth rate differences of larval Baltic sprat Sprattus sprattus collected with bongo and MIK nets.

    Science.gov (United States)

    Fey, D P

    2015-01-01

    The effect of sampling with bongo (0·6 m diameter frame with 500 µm mesh) and Methot Isaac Kidd (MIK) (2 m diameter frame with 2 mm mesh finished with 500 µm codend) nets on standard length (LS ) range and growth rate differences was tested for larval Sprattus sprattus (n = 906, LS range: 7·0-34·5 mm) collected during four cruises in the summer months of 2006, 2007, 2009 and 2010 in the southern Baltic Sea. Although the minimum size of larvae collected with the bongo and MIK nets was similar in each cruise (from c. 7 to 9 mm), the MIK nets permitted collecting larger specimens (up to c. 34 mm) than the bongo nets did (up to c. 27 mm). The growth rates of larvae collected with the bongo and MIK nets (specimens of the same size range were compared for three cruises) were not statistically different (mean = 0·55 mm day(-1) , n = 788, LS range: 7·0-27·4 mm), which means the material collected with these two nets can be combined and growth rate results between them were compared. © 2014 The Fisheries Society of the British Isles.

  2. Growth kinetics and initial stage growth during plasma-enhanced Ti atomic layer deposition

    CERN Document Server

    Kim, H

    2002-01-01

    We have investigated the growth kinetics of plasma-enhanced Ti atomic layer deposition (ALD) using a quartz crystal microbalance. Ti ALD films were grown at temperatures from 20 to 200 deg. C using TiCl sub 4 as a source gas and rf plasma-produced atomic H as the reducing agent. Postdeposition ex situ chemical analyses of thin films showed that the main impurity is oxygen, mostly incorporated during the air exposure prior to analysis. The thickness per cycle, corresponding to the growth rate, was measured by quartz crystal microbalance as a function of various key growth parameters, including TiCl sub 4 and H exposure time, rf plasma power, and sample temperature. The growth rates were independent of TiCl sub 4 exposure above 1x10 sup 3 L, indicating typical ALD mode growth. The key kinetic parameters for Cl extraction reaction and TiCl sub 4 adsorption kinetics were obtained and the growth kinetics were modeled to predict the growth rates based upon these results. Also, the dependency of growth kinetics on d...

  3. Growth of graphene underlayers by chemical vapor deposition

    International Nuclear Information System (INIS)

    Fabiane, Mopeli; Khamlich, Saleh; Bello, Abdulhakeem; Dangbegnon, Julien; Momodu, Damilola; Manyala, Ncholu; Charlie Johnson, A. T.

    2013-01-01

    We present a simple and very convincing approach to visualizing that subsequent layers of graphene grow between the existing monolayer graphene and the copper catalyst in chemical vapor deposition (CVD). Graphene samples were grown by CVD and then transferred onto glass substrates by the bubbling method in two ways, either direct-transfer (DT) to yield poly (methyl methacrylate) (PMMA)/graphene/glass or (2) inverted transfer (IT) to yield graphene/PMMA/glass. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were used to reveal surface features for both the DT and IT samples. The results from FE-SEM and AFM topographic analyses of the surfaces revealed the underlayer growth of subsequent layers. The subsequent layers in the IT samples are visualized as 3D structures, where the smaller graphene layers lie above the larger layers stacked in a concentric manner. The results support the formation of the so-called “inverted wedding cake” stacking in multilayer graphene growth

  4. 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.

  5. Comparison in Schemes for Simulating Depositional Growth of Ice Crystal between Theoretical and Laboratory Data

    Science.gov (United States)

    Zhai, Guoqing; Li, Xiaofan

    2015-04-01

    The Bergeron-Findeisen process has been simulated using the parameterization scheme for the depositional growth of ice crystal with the temperature-dependent theoretically predicted parameters in the past decades. Recently, Westbrook and Heymsfield (2011) calculated these parameters using the laboratory data from Takahashi and Fukuta (1988) and Takahashi et al. (1991) and found significant differences between the two parameter sets. There are two schemes that parameterize the depositional growth of ice crystal: Hsie et al. (1980), Krueger et al. (1995) and Zeng et al. (2008). In this study, we conducted three pairs of sensitivity experiments using three parameterization schemes and the two parameter sets. The pre-summer torrential rainfall event is chosen as the simulated rainfall case in this study. The analysis of root-mean-squared difference and correlation coefficient between the simulation and observation of surface rain rate shows that the experiment with the Krueger scheme and the Takahashi laboratory-derived parameters produces the best rain-rate simulation. The mean simulated rain rates are higher than the mean observational rain rate. The calculations of 5-day and model domain mean rain rates reveal that the three schemes with Takahashi laboratory-derived parameters tend to reduce the mean rain rate. The Krueger scheme together with the Takahashi laboratory-derived parameters generate the closest mean rain rate to the mean observational rain rate. The decrease in the mean rain rate caused by the Takahashi laboratory-derived parameters in the experiment with the Krueger scheme is associated with the reductions in the mean net condensation and the mean hydrometeor loss. These reductions correspond to the suppressed mean infrared radiative cooling due to the enhanced cloud ice and snow in the upper troposphere.

  6. Net expression inhibits the growth of pancreatic ductal adenocarcinoma cell PL45 in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Baiwen Li

    Full Text Available Pancreatic ductal adenocarcinoma has a poor prognosis due to late diagnosis and a lack of effective therapeutic options. Thus, it is important to better understand its molecular mechanisms and to develop more effective treatments for the disease. The ternary complex factor Net, which exerts its strong inhibitory function on transcription of proto-oncogene gene c-fos by forming ternary complexes with a second transcription factor, has been suspected of being involved in pancreatic cancer and other tumors biology. In this study, we found that the majority of pancreatic ductal adenocarcinoma tissues and cell lines had weak or no expression of Net, whereas significantly high level of Net expression occurred in paired adjacent normal tissues we studied. Furthermore, using in vitro and in vivo model systems, we found that overexpression of Net inhibited cell growth and survival and induced cell apoptosis in human pancreatic ductal adenocarcinoma cell PL45; the mechanisms by which Net inhibited the cell cycle progression were mainly through P21-Cyclin D1/CDK4 Pathway. Our data thus suggested that Net might play an important role in pancreatic carcinogenesis, possibly by acting as a tumor suppressor gene.

  7. Nitrogen deposition outweighs climatic variability in driving annual growth rate of canopy beech trees: Evidence from long-term growth reconstruction across a geographic gradient.

    Science.gov (United States)

    Gentilesca, Tiziana; Rita, Angelo; Brunetti, Michele; Giammarchi, Francesco; Leonardi, Stefano; Magnani, Federico; van Noije, Twan; Tonon, Giustino; Borghetti, Marco

    2018-07-01

    In this study, we investigated the role of climatic variability and atmospheric nitrogen deposition in driving long-term tree growth in canopy beech trees along a geographic gradient in the montane belt of the Italian peninsula, from the Alps to the southern Apennines. We sampled dominant trees at different developmental stages (from young to mature tree cohorts, with tree ages spanning from 35 to 160 years) and used stem analysis to infer historic reconstruction of tree volume and dominant height. Annual growth volume (G V ) and height (G H ) variability were related to annual variability in model simulated atmospheric nitrogen deposition and site-specific climatic variables, (i.e. mean annual temperature, total annual precipitation, mean growing period temperature, total growing period precipitation, and standard precipitation evapotranspiration index) and atmospheric CO 2 concentration, including tree cambial age among growth predictors. Generalized additive models (GAM), linear mixed-effects models (LMM), and Bayesian regression models (BRM) were independently employed to assess explanatory variables. The main results from our study were as follows: (i) tree age was the main explanatory variable for long-term growth variability; (ii) GAM, LMM, and BRM results consistently indicated climatic variables and CO 2 effects on G V and G H were weak, therefore evidence of recent climatic variability influence on beech annual growth rates was limited in the montane belt of the Italian peninsula; (iii) instead, significant positive nitrogen deposition (N dep ) effects were repeatedly observed in G V and G H ; the positive effects of N dep on canopy height growth rates, which tended to level off at N dep values greater than approximately 1.0 g m -2  y -1 , were interpreted as positive impacts on forest stand above-ground net productivity at the selected study sites. © 2018 John Wiley & Sons Ltd.

  8. Whole Watershed Quantification of Net Carbon Fluxes by Erosion and Deposition within the Christina River Basin Critical Zone Observatory

    Science.gov (United States)

    Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

    2013-12-01

    to organic carbon and nitrogen content with stable isotope (13C, 15N) and radiocarbon (14C) abundance to quantify OC/SA and organic carbon sources and mean age. We then use multivariate mixing model analysis to quantify the fractional contribution of each source end-member to each sample of suspended or deposited sediments. Last, we calculate a predicted OC/SA based on source end-member mixing and compare to the measured OC/SA to quantify net change in mineral complexed carbon. Aufdenkampe, A.K. et al. Riverine coupling of biogeochemical cycles between land, oceans, and atmosphere. Frontiers Ecol. Environ. 9, 53-60 (2011). Walling, D. E. Tracing suspended sediment sources in catchments and river systems. Sci. Total Environ. 34, 159-184 (2005).

  9. Renewable and non-renewable energy consumption and economic growth: Evidence from MENA Net Oil Exporting Countries.

    OpenAIRE

    Kahia, Montassar; Ben Aissa, Mohamed Safouane

    2014-01-01

    This study investigate the relationship between renewable and non-renewable energy consumption and economic growth in a sample of 13 MENA Net Oil Exporting Countries covering the period 1980–2012 within a multivariate panel framework. The Pedroni (1999, 2004), Kao (1999) as well as the Westerlund (2007) panel cointegration tests indicate that there is a long-run equilibrium relationship between real GDP, renewable energy consumption, non-renewable energy consumption, real gross fixed capital ...

  10. Renewable and non-renewable energy consumption and economic growth: Evidence from MENA Net Oil Importing Countries

    OpenAIRE

    Kahia, Montassar; Ben Aissa, Mohamed Safouane

    2014-01-01

    In this paper, we use panel cointegration techniques to explore the relationship between renewable and non-renewable energy consumption and economic growth in a sample of 11 MENA Net Oil Importing Countries covering the period 1980–2012. The Pedroni (1999, 2004), Kao(1999) as well as Westerlund(2007) panel cointegration tests indicate that there is a long-run equilibrium relationship between real GDP, renewable energy consumption, non-renewable energy consumption, real gross fixed capital for...

  11. On the Growth and Microstructure of Carbon Nanotubes Grown by Thermal Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Handuja Sangeeta

    2010-01-01

    Full Text Available Abstract Carbon nanotubes (CNTs were deposited on various substrates namely untreated silicon and quartz, Fe-deposited silicon and quartz, HF-treated silicon, silicon nitride-deposited silicon, copper foil, and stainless steel mesh using thermal chemical vapor deposition technique. The optimum parameters for the growth and the microstructure of the synthesized CNTs on these substrates are described. The results show that the growth of CNTs is strongly influenced by the substrate used. Vertically aligned multi-walled CNTs were found on quartz, Fe-deposited silicon and quartz, untreated silicon, and on silicon nitride-deposited silicon substrates. On the other hand, spaghetti-type growth was observed on stainless steel mesh, and no CNT growth was observed on HF-treated silicon and copper. Silicon nitride-deposited silicon substrate proved to be a promising substrate for long vertically aligned CNTs of length 110–130 μm. We present a possible growth mechanism for vertically aligned and spaghetti-type growth of CNTs based on these results.

  12. Nickel deposition effects on the growth of carbon nanofibers on carbon paper

    NARCIS (Netherlands)

    Celebi, S.; Schaaf, van der J.; Nijhuis, T.A.; Bruijn, de F.A.; Schouten, J.C.

    2010-01-01

    Carbon nanofiber (CNF) growth has been achieved on carbon paper fibers via two nickel deposition routes: i. nickel nanoparticle-ethanol suspension casting, and ii. homogenous deposition precipitation (HDP) of nickel onto carbon paper. Nickel nanoparticles created regular tubular CNF whereas HDP of

  13. 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.

  14. Chemical solution deposition techniques for epitaxial growth of complex oxides

    NARCIS (Netherlands)

    ten Elshof, Johan E.; Koster, G.; Huijben, Mark; Rijnders, G.

    2015-01-01

    The chemical solution deposition (CSD) process is a wet-chemical process that is employed to fabricate a wide variety of amorphous and crystalline oxide thin films. This chapter describes the typical steps in a CSD process and their influence on the final microstructure and properties of films, and

  15. Epitaxial growth with pulsed deposition: Submonolayer scaling and Villain instability

    DEFF Research Database (Denmark)

    Hinnemann, Berit; Hinrichsen, H.; Wolf, D.E.

    2003-01-01

    It has been observed experimentally that under certain conditions, pulsed laser deposition (PLD) produces smoother surfaces than ordinary molecular beam epitaxy (MBE). So far, the mechanism leading to the improved quality of surfaces in PLD is not yet fully understood. In the present work, we...

  16. Short Communication Validation of growth zone deposition rate in ...

    African Journals Online (AJOL)

    Flathead mullet Mugil cephalus and freshwater mullet Myxus capensis are important components in South African estuarine fish communities and fisheries, but there is little information on their age and growth or age validation. This study validated the periodicity of growth zone formation in sectioned sagittal otoliths and ...

  17. Arius kesslerl & Sciadeops troschelii (Pisces: Ariidae growth in floating net cages in estuarine waters of Buenventura Bay-Colombia

    Directory of Open Access Journals (Sweden)

    Efraín Alfonso Rubio

    1999-07-01

    Full Text Available Two species of estuary catfish the Arius kessleri (CoCoCo and the Sciadeops troschelii (Nato were held in floating net cages at varying densities in estuarine waters of Buenventura Bay-Colombia. After 120 days for the Cococo had weights of 84.1 g Y64 g with densities of 5 and 30 specimen/rn'. The growth average was 0.58-0.39 g/day; the net yield obtained vary from 0.35 to 1.16 Kg/m', the food conversion ratio vary from 3.3 to 5.0 and de survival rate vary from 86% to 100%. With the Nato we obtained weights of 164 and 184 g, beginning with weights of 41 and 108 g their growth average vary from 0.50 to 0.82 g/day. The net yield obtained vary from 0.58 to 0.75 Kg/m' and the survival rate vary from 83% to 100%. From these results we conclude that the two species of catfish studied are strong species but they do not offer good possibilities for fish farming in estuarine waters.

  18. Efficacy of insect-proof nets used in Tunisian tomato greenhouses against Tuta absoluta (Meyrick (Lepidoptera: Gelechiidae and potential impact on plant growth and fruit quality

    Directory of Open Access Journals (Sweden)

    A. Harbi

    2015-12-01

    Full Text Available Insect-proof screens constitute efficient physical means of protecting horticultural crops against insect pests and their use has become widespread. However, they may have a negative impact on plant growth and fruit quality by modifying climatic parameters of greenhouses. In case of tomato crops, they are used mainly against white flies and the tomato leaf miner Tuta absoluta (Meyrick. In Tunisia, tomato plastic tunnels are often netted following two modalities: i complete netting of the greenhouse under the plastic screen (total netting; or ii netting only doors and lateral aeration windows (partial netting. Weekly monitoring of T. absoluta in two tomato greenhouses with different netting setups using pheromone traps and sampling of leaves and fruits showed no differences in the levels of infestation by the pest with a maximum average values of 6.66 eggs/leaf, 4.16 larvae/leaf and 4.16 mines/leaf. The maximum infestation rate of leaves was 86.66% and that of fruits was 10.83%. No effects of the netting setup used on plant growth parameters were detected. However, the study of fruit quality parameters revealed significant decrease in sugar contents in tomato fruits when using total netting setup (4.26°Brix versus 3.68°Brix. Recommendations regarding the combined use of pheromones traps and insect-proof nets are given and possibilities to enhance the efficiency of nets as physical barrier against T. absoluta are explored.

  19. Surface morphology and preferential orientation growth of TaC crystals formed by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Xiang, E-mail: Xiong228@sina.co [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China); Chen Zhaoke; Huang Baiyun; Li Guodong [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China); Zheng Feng [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Xiao Peng; Zhang Hongbo [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China)

    2009-04-02

    TaC film was deposited on (002) graphite sheet by isothermal chemical vapor deposition using TaCl{sub 5}-Ar-C{sub 3}H{sub 6} mixtures, with deposition temperature 1200 {sup o}C and pressure about 200 Pa. The influence of deposition position (or deposition rate) on preferential orientation and surface morphology of TaC crystals were investigated by X-ray diffraction and scanning electron microscopy methods. The deposits are TaC plus trace of C. The crystals are large individual columns with pyramidal-shape at deposition rate of 32.4-37.3 {mu}m/h, complex columnar at 37.3-45.6 {mu}m/h, lenticular-like at 45.6-54.6 {mu}m/h and cauliflower-like at 54.6-77.3 {mu}m/h, with <001>, near <001>, <110> and no clear preferential orientation, respectively. These results agree in part with the preditions of the Pangarov's model of the relationship between deposition rate and preferential growth orientation. The growth mechanism of TaC crystals in <001>, near <001>, <111> and no clear preferential orientation can be fairly explained by the growth parameter {alpha} with Van der Drift's model, deterioration model and Meakin model. Furthermore, a nucleation and coalescence model is also proposed to explain the formation mechanism of <110> lenticular-like crystals.

  20. Evaluation of the growth of carbonaceous deposit in steady state Tore Supra using infrared thermography

    International Nuclear Information System (INIS)

    Mitteau, R.; Guilhem, D.; Reichle, R.; Vallet, J.C.; Roche, H.; Buravand, Y.; Chantant, M.; Tsitrone, E.; Brosset, C.; Grosman, A.; Chappuis, P.

    2006-01-01

    Fusion devices with carbon as the main armour material are experiencing a growth in carbonaceous deposits at the surface of the plasma facing components. Tore Supra presents such deposits, and has specific features which influence their growth: long pulse operation and cooled walls. Deposits have a low thermal transfer to the cooled structure so that they appear as hot areas with the infrared imaging system looking at the elements surface temperature during plasma discharges. A 'degree of (carbon) deposit' on the toroidal pumped limiter is estimated by establishing the ratio between the apparent power on the limiter derived from the infrared measure and the actual one, deduced from a power balance analysis between the injected and the radiated power. This criterion is used to monitor the evolution of the deposit average thermal resistance. Successive shots have a similar 'degree of deposit', showing that the evaluation makes sense. Two years of data have been compiled (2003 and 2004), representing 3000 discharges (13 h of plasma, including 30 discharges longer than one minute). A three-fold increase in the 'degree of deposit' over six months is evidenced, following a limiter clean-up early in 2003. A comparison with calorimetric data produces a similar result, albeit less pronounced. Large steps in the degree of deposit are sometimes observed, usually correlated with identified events such as disruption, vessel opening, conditioning or plasma parameters change. It indicates that the deposit thermal resistance can change rapidly, although a systematic correlation with the above mentioned events could not be established

  1. Evaluation of the growth of carbonaceous deposit in steady state Tore Supra using infrared thermography

    Science.gov (United States)

    Mitteau, R.; Guilhem, D.; Reichle, R.; Vallet, J. C.; Roche, H.; Buravand, Y.; Chantant, M.; Tsitrone, E.; Brosset, C.; Grosman, A.; Chappuis, P.

    2006-03-01

    Fusion devices with carbon as the main armour material are experiencing a growth in carbonaceous deposits at the surface of the plasma facing components. Tore Supra presents such deposits, and has specific features which influence their growth: long pulse operation and cooled walls. Deposits have a low thermal transfer to the cooled structure so that they appear as hot areas with the infrared imaging system looking at the elements surface temperature during plasma discharges. A 'degree of (carbon) deposit' on the toroidal pumped limiter is estimated by establishing the ratio between the apparent power on the limiter derived from the infrared measure and the actual one, deduced from a power balance analysis between the injected and the radiated power. This criterion is used to monitor the evolution of the deposit average thermal resistance. Successive shots have a similar 'degree of deposit', showing that the evaluation makes sense. Two years of data have been compiled (2003 and 2004), representing 3000 discharges (13 h of plasma, including 30 discharges longer than one minute). A three-fold increase in the 'degree of deposit' over six months is evidenced, following a limiter clean-up early in 2003. A comparison with calorimetric data produces a similar result, albeit less pronounced. Large steps in the degree of deposit are sometimes observed, usually correlated with identified events such as disruption, vessel opening, conditioning or plasma parameters change. It indicates that the deposit thermal resistance can change rapidly, although a systematic correlation with the above mentioned events could not be established.

  2. Growth and characterization of titanium oxide by plasma enhanced atomic layer deposition

    KAUST Repository

    Zhao, Chao; Hedhili, Mohamed N.; Li, Jingqi; Wang, Qingxiao; Yang, Yang; Chen, Long; LI, LIANG

    2013-01-01

    The growth of TiO2 films by plasma enhanced atomic layer deposition using Star-Ti as a precursor has been systematically studied. The conversion from amorphous to crystalline TiO2 was observed either during high temperature growth or annealing

  3. 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....

  4. Modified Stranski-Krastanov growth in Ge/Si heterostructures via nanostenciled pulsed laser deposition.

    Science.gov (United States)

    MacLeod, J M; Cojocaru, C V; Ratto, F; Harnagea, C; Bernardi, A; Alonso, M I; Rosei, F

    2012-02-17

    The combination of nanostenciling with pulsed laser deposition (PLD) provides a flexible, fast approach for patterning the growth of Ge on Si. Within each stencilled site, the morphological evolution of the Ge structures with deposition follows a modified Stranski-Krastanov (SK) growth mode. By systematically varying the PLD parameters (laser repetition rate and number of pulses) on two different substrate orientations (111 and 100), we have observed corresponding changes in growth morphology, strain and elemental composition using scanning electron microscopy, atomic force microscopy and μ-Raman spectroscopy. The growth behaviour is well predicted within a classical SK scheme, although the Si(100) growth exhibits significant relaxation and ripening with increasing coverage. Other novel aspects of the growth include the increased thickness of the wetting layer and the kinetic control of Si/Ge intermixing via the PLD repetition rate.

  5. 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.

  6. 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

  7. Fatigue Crack Growth Behavior and Microstructural Mechanisms in Ti-6Al-4V Manufactured by Laser Engineered Net Shaping

    Science.gov (United States)

    2015-12-01

    rapid manufactured Inconel 625 structures, Materials Science and Engineering A, vol. 527(29-30), pp. 7490-7497, 2010. 18 Approved for public release...4V and Inconel 718. Although porosity was observed in both laser deposited materials, their fatigue performance was found comparable to their...growth 2 Approved for public release; distribution is unlimited rates of laser rapid manufactured and wrought In- 625 alloys. It was noted that fatigue

  8. 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

  9. 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.

  10. 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.

  11. Low power high growth rate deposition of microcrystalline silicon

    OpenAIRE

    Feltrin, A; Bugnon, G; Meillaud, F; Bailat, J; Ballif, C

    2008-01-01

    Microcrystalline growth regimes and solar cells obtained in different pressure and silane depletion conditions are studied in a large area KAI-S plasma reactor. The microcrystalline material quality is systematically investigated by Fourier Transform Photocurrent Spectroscopy (FTPS) to evaluate the defect density. It is shown that higher pressure and silane depletion positively affect the material quality. A clear correlation between FTPS measurements and cell efficiency is established, showi...

  12. Vascular endothelial growth factor receptor-3 is a novel target to improve net ultrafiltration in methylglyoxal-induced peritoneal injury.

    Science.gov (United States)

    Terabayashi, Takeshi; Ito, Yasuhiko; Mizuno, Masashi; Suzuki, Yasuhiro; Kinashi, Hiroshi; Sakata, Fumiko; Tomita, Takako; Iguchi, Daiki; Tawada, Mitsuhiro; Nishio, Ryosuke; Maruyama, Shoichi; Imai, Enyu; Matsuo, Seiichi; Takei, Yoshifumi

    2015-09-01

    Appropriate fluid balance is important for good clinical outcomes and survival in patients on peritoneal dialysis. We recently reported that lymphangiogenesis associated with fibrosis developed in the peritoneal cavity via the transforming growth factor-β1-vascular endothelial growth factor-C (VEGF-C) pathway. We investigated whether VEGF receptor-3 (VEGFR-3), the receptor for VEGF-C and -D, might be a new target to improve net ultrafiltration by using adenovirus-expressing soluble VEGFR-3 (Adeno-sVEGFR-3) in rodent models of peritoneal injury induced by methylglyoxal (MGO). We demonstrated that lymphangiogenesis developed in these MGO models, especially in the diaphragm, indicating that lymphangiogenesis is a common feature in the peritoneal cavity with inflammation and fibrosis. In MGO models, VEGF-D was significantly increased in the diaphragm; however, VEGF-C was not significantly upregulated. Adeno-sVEGFR-3, which was detected on day 50 after administration via tail vein injections, successfully suppressed lymphangiogenesis in the diaphragm and parietal peritoneum in mouse MGO models without significant effects on fibrosis, inflammation, or neoangiogenesis. Drained volume in the peritoneal equilibration test using a 7.5% icodextrin peritoneal dialysis solution (the 7.5% icodextrin peritoneal equilibration test) was improved by Adeno-sVEGFR-3 on day 22 (Ptarget to improve net ultrafiltration by suppressing lymphatic absorption and that the 7.5% icodextrin peritoneal equilibration test is useful for estimation of lymphatic absorption.

  13. How closely does stem growth of adult beech (Fagus sylvatica) relate to net carbon gain under experimentally enhanced ozone stress?

    International Nuclear Information System (INIS)

    Kitao, Mitsutoshi; Winkler, J. Barbro; Löw, Markus; Nunn, Angela J.; Kuptz, Daniel; Häberle, Karl-Heinz; Reiter, Ilja M.; Matyssek, Rainer

    2012-01-01

    The hypothesis was tested that O 3 -induced changes in leaf-level photosynthetic parameters have the capacity of limiting the seasonal photosynthetic carbon gain of adult beech trees. To this end, canopy-level photosynthetic carbon gain and respiratory carbon loss were assessed in European beech (Fagus sylvatica) by using a physiologically based model, integrating environmental and photosynthetic parameters. The latter were derived from leaves at various canopy positions under the ambient O 3 regime, as prevailing at the forest site (control), or under an experimental twice-ambient O 3 regime (elevated O 3 ), as released through a free-air canopy O 3 fumigation system. Gross carbon gain at the canopy-level declined by 1.7%, while respiratory carbon loss increased by 4.6% under elevated O 3 . As this outcome only partly accounts for the decline in stem growth, O 3 -induced changes in allocation are referred to and discussed as crucial in quantitatively linking carbon gain with stem growth. - Highlights: ► We model O 3 -induced changes in the photosynthetic carbon gain of adult beech trees. ► Elevated O 3 decreases gross carbon gain but increases respiratory carbon loss. ► Reduction in net carbon gain only partly accounts for the decline in stem growth. ► O 3 effects on the whole-tree allocation is crucial in addition to carbon gains. - Reduction in net carbon gain at the canopy level only partly accounts for the decline in stem growth under elevated ozone.

  14. Catalyst-free growth of InN nanorods by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Kim, Min Hwa; Moon, Dae Young; Park, Jinsub; Nanishi, Yasushi; Yi, Gyu-Chul; Yoon, Euijoon

    2012-01-01

    We demonstrated the growth of catalyst-free InN nanostructures including nanorods on (0001) Al 2 O 3 substrates using metal-organic chemical vapor deposition. As the growth time increased, growth rate along c-direction increased superlinearly with decreasing c-plane area fractions and increasing side wall areas. It was also found that desorption from the sidewalls of InN nanostructures during the InN nanorods formation was one of essential key parameters of the growth mechanism. We propose a growth model to explain the InN nanostructure evolution by considering the side wall desorption and re-deposition of indium at top c-plane surfaces. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Canopy uptake of atmospheric N deposition at a conifer forest: part I -canopy N budget, photosynthetic efficiency and net ecosystem exchange

    International Nuclear Information System (INIS)

    Sievering, H.; Tomaszewski, T.; Torizzo, J.

    2007-01-01

    Global carbon cycle assessments of anthropogenic nitrogen (N) deposition influences on carbon sequestration often assume enhanced sequestration results. This assumption was evaluated at a Rocky Mountains spruce-fir forest. Forest canopy N uptake (CNU) of atmospheric N deposition was estimated by combining event wet and throughfall N fluxes with gradient measured HNO 3 and NH 3 as well as inferred (NO x and particulate N) dry fluxes. Approximately 80% of the growing-season 3 kg N/ha total deposition is retained in canopy foliage and branches. This CNU constitutes ∼1/3 of canopy growing season new N supply at this conifer forest site. Daytime net ecosystem exchange (NEE) significantly (P = 0.006) and negatively (CO 2 uptake) correlated with CNU. Multiple regression indicates ∼20% of daytime NEE may be attributed to CNU (P < 0.02); more than soil water content. A wet deposition N-amendment study (Tomaszewski and Sievering), at canopy spruce branches, increased their growing-season CNU by 40-50% above ambient. Fluorometry and gas exchange results show N-amended spruce branches had greater photosynthetic efficiency and higher carboxylation rates than control and untreated branches. N-amended branches had 25% less photoinhibition, with a 5-9% greater proportion of foliar-N-in-Rubisco. The combined results provide, partly, a mechanistic explanation for the NEE dependence on CNU

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

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Pryds, Nini; Schou, Jørgen

    the preparation of ultrathin seed layers in the first stage of the deposition process is often envisaged to control the growth and physical properties of the subsequent coating. This work suggests that the limitations of conventional pulsed laser deposition (PLD), performed at moderate temperature (400°C......10 layers with a thickness of 4 nm, 13 nm and 22 nm, respectively, grown on Mg(100), were studied by atomic force microscopy and X-ray reflectometry....

  17. Nucleation and growth of copper phthalocyanine aggregates deposited from solution on planar surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ghani, Fatemeh [Department of Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1 Golm, 14476 Potsdam (Germany); Gojzewski, Hubert, E-mail: hubert.gojzewski@put.poznan.pl [Department of Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1 Golm, 14476 Potsdam (Germany); Institute of Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan (Poland); Riegler, Hans [Department of Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1 Golm, 14476 Potsdam (Germany)

    2015-10-01

    Graphical abstract: - Highlights: • Copper phthalocyanine deposited on planar surfaces by 3 solution process methods. • Aggregate morphology examined for coverage extending over 3 orders of magnitude. • Morphologies vary from small individual domains to mesh-like multilayers. • Nucleation and growth model explains the observed deposit morphologies. - Abstract: Copper phthalocyanine (CuPc) dissolved in trifluoroacetic acid (TFA) is deposited on solid SiO{sub 2} surfaces by solvent evaporation. The deposited CuPc aggregates are investigated by atomic force microscopy (AFM). The CuPc deposits were prepared by spin casting, dip coating, and spray deposition. Depending on the amount of deposited CuPc the aggregate morphology ranges from small individual domains to mesh-like multilayers. Each domain/layer consists of many parallel stacks of CuPc molecules with the square, plate-like molecules piled face-wise within each stack. The parallel stacks are attached sideways (i.e., edgewise attachment molecularly) to the substrate forming “nanoribbons” with uniform thickness of about 1 nm and varying width. The thickness reflects the length of a molecular edge, the width the number of stacks. A nucleation and growth model is presented that explains the observed aggregate and multilayer morphologies as result of the combination of nucleation, transport processes and a consequence of the anisotropic intermolecular interactions due to the shape of the CuPc molecule.

  18. Effect of vapor-phase oxygen on chemical vapor deposition growth of graphene

    Science.gov (United States)

    Terasawa, Tomo-o.; Saiki, Koichiro

    2015-03-01

    To obtain a large-area single-crystal graphene, chemical vapor deposition (CVD) growth on Cu is considered the most promising. Recently, the surface oxygen on Cu has been found to suppress the nucleation of graphene. However, the effect of oxygen in the vapor phase was not elucidated sufficiently. Here, we investigate the effect of O2 partial pressure (PO2) on the CVD growth of graphene using radiation-mode optical microscopy. The nucleation density of graphene decreases monotonically with PO2, while its growth rate reaches a maximum at a certain pressure. Our results indicate that PO2 is an important parameter to optimize in the CVD growth of graphene.

  19. 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)

  20. Fast vertical growth of ZnO nanorods using a modified chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tae-hyun [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, Hyukhyun, E-mail: hhryu@inje.ac.kr [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Lee, Won-Jae [Department of Materials and Components Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of)

    2014-06-01

    Highlights: • We grew vertical ZnO nanorods by a modified CBD process with a fast growth rate. • We studied the effects of the CBD process by varying growth temperature, time, and concentration. • The ZnO nanorods grown by the modified CBD showed good morphological and structural properties. - Abstract: In this study, we grew vertical ZnO nanorods on seeded Si (1 0 0) substrates using a modified chemical bath deposition (CBD). We investigated the effects of the growth temperature, growth time and concentration on the morphological and structural properties of the ZnO nanorods using field emission gun scanning electron microscopy (FEG-SEM) and X-ray diffraction. This modified CBD method shows improved results over conventional CBD. ZnO nanorods with good structural XRD properties were grown with a very fast growth rate in a wide range of growth conditions and did not require post-growth annealing.

  1. 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

  2. Developing Inventory Projection Models Using Empirical Net Forest Growth and Growing-Stock Density Relationships Across U.S. Regions and Species Group

    Science.gov (United States)

    Prakash Nepal; Peter J. Ince; Kenneth E. Skog; Sun J. Chang

    2012-01-01

    This paper describes a set of empirical net forest growth models based on forest growing-stock density relationships for three U.S. regions (North, South, and West) and two species groups (softwoods and hardwoods) at the regional aggregate level. The growth models accurately predict historical U.S. timber inventory trends when we incorporate historical timber harvests...

  3. Anthropogenic nitrogen deposition alters growth responses of European beech (Fagus sylvativa L.) to climate change.

    Science.gov (United States)

    Hess, Carsten; Niemeyer, Thomas; Fichtner, Andreas; Jansen, Kirstin; Kunz, Matthias; Maneke, Moritz; von Wehrden, Henrik; Quante, Markus; Walmsley, David; von Oheimb, Goddert; Härdtle, Werner

    2018-02-01

    Global change affects the functioning of forest ecosystems and the services they provide, but little is known about the interactive effects of co-occurring global change drivers on important functions such as tree growth and vitality. In the present study we quantified the interactive (i.e. synergistic or antagonistic) effects of atmospheric nitrogen (N) deposition and climatic variables (temperature, precipitation) on tree growth (in terms of tree-ring width, TRW), taking forest ecosystems with European beech (Fagus sylvatica L.) as an example. We hypothesised that (i) N deposition and climatic variables can evoke non-additive responses of the radial increment of beech trees, and (ii) N loads have the potential to strengthen the trees' sensitivity to climate change. In young stands, we found a synergistic positive effect of N deposition and annual mean temperature on TRW, possibly linked to the alleviation of an N shortage in young stands. In mature stands, however, high N deposition significantly increased the trees' sensitivity to increasing annual mean temperatures (antagonistic effect on TRW), possibly due to increased fine root dieback, decreasing mycorrhizal colonization or shifts in biomass allocation patterns (aboveground vs. belowground). Accordingly, N deposition and climatic variables caused both synergistic and antagonistic effects on the radial increment of beech trees, depending on tree age and stand characteristics. Hence, the nature of interactions could mediate the long-term effects of global change drivers (including N deposition) on forest carbon sequestration. In conclusion, our findings illustrate that interaction processes between climatic variables and N deposition are complex and have the potential to impair growth and performance of European beech. This in turn emphasises the importance of multiple-factor studies to foster an integrated understanding and models aiming at improved projections of tree growth responses to co-occurring drivers

  4. 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

  5. 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.

  6. Anthropogenic nitrogen deposition ameliorates the decline in tree growth caused by a drier climate.

    Science.gov (United States)

    Ibáñez, Inés; Zak, Donald R; Burton, Andrew J; Pregitzer, Kurt S

    2018-02-01

    Most forest ecosystems are simultaneously affected by concurrent global change drivers. However, when assessing these effects, studies have mainly focused on the responses to single factors and have rarely evaluated the joined effects of the multiple aspects of environmental change. Here, we analyzed the combined effects of anthropogenic nitrogen (N) deposition and climatic conditions on the radial growth of Acer saccharum, a dominant tree species in eastern North American forests. We capitalized on a long-term N deposition study, replicated along a latitudinal gradient, that has been taking place for more than 20 yr. We analyzed tree radial growth as a function of anthropogenic N deposition (ambient and experimental addition) and of summer temperature and soil water conditions. Our results reveal that experimental N deposition enhances radial growth of this species, an effect that was accentuated as temperature increased and soil water became more limiting. The spatial and temporal extent of our data also allowed us to assert that the positive effects of growing under the experimental N deposition are likely due to changes in the physiological performance of this species, and not due to the positive correlation between soil N and soil water holding capacity, as has been previously speculated in other studies. Our simulations of tree growth under forecasted climate scenarios specific for this region also revealed that although anthropogenic N deposition may enhance tree growth under a large array of environmental conditions, it will not mitigate the expected effects of growing under the considerably drier conditions characteristic of our most extreme climatic scenario. © 2018 by the Ecological Society of America.

  7. Epitaxial crystal growth by sputter deposition: Applications to semiconductors. Part 2

    International Nuclear Information System (INIS)

    Greene, J.E.

    1984-01-01

    The understanding of the physics of ion-surface interactions has progressed sufficiently to allow sputter depositinn to be used as a crystal growth technique for depositing a wide variety of single crystal elemental, compound, alloy, and superlattice semiconductors. In many cases, films with essentially bulk values of carrier concentrations and mobilities have been obtained. The controlled use of low energy particle bombardment of the growing film during sputter deposition has been shown to affect all stages of crystal growth ranging from adatom mobilities and nucleation kinetics to elemental incorporation probabilities. Such effects provide inherent advantages for sputter deposition over other vapor phase techniques for the low temperature growth of compound and alloy semiconductors and are essential in allowing the growth of new and unique single crystal metastable semiconductors. Part 1 of this review includes sections on experimental techniques, the physics of ion-surface interactions, and ion bombardment effects on film nucleation and growth, while Part 2 presents a discussion of recent results in the growth of elemental, III-V, II-VI, IV-VI, metastable, and other compound semiconductors

  8. Low temperature metal free growth of graphene on insulating substrates by plasma assisted chemical vapor deposition

    Science.gov (United States)

    Muñoz, R.; Munuera, C.; Martínez, J. I.; Azpeitia, J.; Gómez-Aleixandre, C.; García-Hernández, M.

    2017-03-01

    Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650 °C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω sq-1. The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies.

  9. Formation of banded vegetation patterns resulted from interactions between sediment deposition and vegetation growth.

    Science.gov (United States)

    Huang, Tousheng; Zhang, Huayong; Dai, Liming; Cong, Xuebing; Ma, Shengnan

    2018-03-01

    This research investigates the formation of banded vegetation patterns on hillslopes affected by interactions between sediment deposition and vegetation growth. The following two perspectives in the formation of these patterns are taken into consideration: (a) increased sediment deposition from plant interception, and (b) reduced plant biomass caused by sediment accumulation. A spatial model is proposed to describe how the interactions between sediment deposition and vegetation growth promote self-organization of banded vegetation patterns. Based on theoretical and numerical analyses of the proposed spatial model, vegetation bands can result from a Turing instability mechanism. The banded vegetation patterns obtained in this research resemble patterns reported in the literature. Moreover, measured by sediment dynamics, the variation of hillslope landform can be described. The model predicts how treads on hillslopes evolve with the banded patterns. Thus, we provide a quantitative interpretation for coevolution of vegetation patterns and landforms under effects of sediment redistribution. Copyright © 2018. Published by Elsevier Masson SAS.

  10. Validation of growth zone deposition in otoliths of two large endemic ...

    African Journals Online (AJOL)

    We tested the hypothesis that growth zones in the astericus otoliths of smallmouth yellowfish (Labeobarbus aeneus) and Orange River mudfish (Labeo capensis) were deposited annually. Two methods, fluorochrome marking and edge analysis of otoliths were used. For fluorochrome marking, specimens of both species ...

  11. Potassium limits potential growth of bog vegetation under elevated atmospheric CO2 and N deposition

    NARCIS (Netherlands)

    Hoosbeek, M.R.; Breemen, van N.; Vasander, H.; Buttlers, A.; Berendse, F.

    2002-01-01

    The free air carbon dioxide enrichment (FACE) and N deposition experiments on four ombrotrophic bogs in Finland, Sweden, the Netherlands and Switzerland, revealed that after three years of treatment: (1) elevated atmospheric CO2 concentration had no significant effect on the biomass growth of

  12. Plasma-deposited aluminum-doped zinc oxide : controlling nucleation, growth and electrical properties

    NARCIS (Netherlands)

    Ponomarev, M.

    2012-01-01

    In this work, the Expanding Thermal Plasma (ETP) deposition technique was employed to study the growth development of ZnO:Al thin film as a transparent conductive oxide layer for sustainable applications. Characteristic for ETP-grown ZnO:Al is a gradually reducing resistivity of the growing layer

  13. 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

  14. 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

  15. PECVD deposition of device-quality intrinsic amorphous silicon at high growth rate

    Energy Technology Data Exchange (ETDEWEB)

    Carabe, J [Inst. de Energias Renovables, CIEMAT, Madrid (Spain); Gandia, J J [Inst. de Energias Renovables, CIEMAT, Madrid (Spain); Gutierrez, M T [Inst. de Energias Renovables, CIEMAT, Madrid (Spain)

    1993-11-01

    The combined influence of RF-power density (RFP) and silane flow-rate ([Phi]) on the deposition rate of plasma-enhanced chemical vapour deposition (PECVD) intrinsic amorphous silicon has been investigated. The correlation of the results obtained from the characterisation of the material with the silane deposition efficiency, as deduced from mass spectrometry, has led to an interpretation allowing to deposit intrinsic amorphous-silicon films having an optical gap of 1.87 eV and a photoconductive ratio (ratio of ambient-temperature conductivities under 1 sun AM1 and in dark) of 6 orders of magnitude at growth rates up to 10 A/s, without any structural modification of the PECVD system used. Such results are considered of high relevance regarding industrial competitiveness. (orig.)

  16. Phase diagram of interfacial growth modes by vapor deposition and its application for ZnO nanostructures

    Science.gov (United States)

    Shu, Da-Jun; Xiong, Xiang; Liu, Ming; Wang, Mu

    2017-09-01

    Interfacial growth from vapor has been extensively studied. However, a straightforward picture of the growth mode under different growth conditions is still lacking. In this paper, we develop a comprehensive interfacial growth theory based on the stochastic approach. Using a critical interisland separation, we construct a general phase diagram of the growth modes. It has been revealed that if the Ehrlich-Schwoebel barrier EES is smaller than a critical value, the interfacial growth proceeds in a layer-by-layer (LBL) mode at any deposition rate. However, if EES is larger than the critical value, LBL growth occurs only at very small or very large deposition rates relative to the intralayer hopping rate, and multilayer (ML) growth occurs at a moderate deposition rate. Experiments with zinc oxide growth by chemical vapor deposition have been designed to qualitatively demonstrate the theoretical model. By changing the flux of the carrier gas (nitrogen gas) in chemical vapor deposition, we realize LBL, ML, and then reentrance of LBL homoepitaxial growth of ZnO successively. Moreover, we find that surface kinetics of ZnO is suppressed by decreasing oxygen partial pressure by comparing the experimental observations and theoretical models, which is supported by our recent first-principles calculations. Since the influence of the substrate and the growth species on growth can approximately be represented by binding energy and surface kinetics, we suggest that the phase diagram is essential for interfacial growth of different materials by vapor deposition.

  17. 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.

  18. Ge incorporation inside 4H-SiC during Homoepitaxial growth by chemical vapor deposition

    OpenAIRE

    Alassaad, Kassem; Soulière, Véronique; Cauwet, François; Peyre, Hervé; Carole, Davy; Kwasnicki, Pawel; Juillaguet, Sandrine; Kups, Thomas; Pezoldt, Jörg; Ferro, Gabriel

    2014-01-01

    8 pages; International audience; In this work, we report on the addition of GeH4 gas during homoepitaxial growth of 4H-SiC by chemical vapour deposition. Ge introduction does not affect dramatically the surface morphology and defect density though it is accompanied with Ge droplets accumulation at the surface. The Ge incorporation level inside the 4H-SiC matrix, ranging from few 1017 to few 1018 at.cm-3, was found to be mainly affected by the growth temperature and GeH4 flux. Other growth par...

  19. Growth and characterization of titanium oxide by plasma enhanced atomic layer deposition

    KAUST Repository

    Zhao, Chao

    2013-09-01

    The growth of TiO2 films by plasma enhanced atomic layer deposition using Star-Ti as a precursor has been systematically studied. The conversion from amorphous to crystalline TiO2 was observed either during high temperature growth or annealing process of the films. The refractive index and bandgap of TiO2 films changed with the growth and annealing temperatures. The optimization of the annealing conditions for TiO2 films was also done by morphology and density studies. © 2013 Elsevier B.V. All rights reserved.

  20. Power deposition profiles and Poynting vector distribution of phased antenna arrays in the ion-cyclotron resonance heating of a NET/INTOR-type tokamak

    International Nuclear Information System (INIS)

    Bhatnagar, V.P.; Koch, R.

    1986-01-01

    The heating produced by magnetosonic waves launched from phased antenna arrays in the ion-cyclotron range of frequencies is studied for a large tokamak with NET/INTOR-like parameters. The model used combines a 3-D planar, cold-plasma, antenna-plasma coupling code and a 3-D non-circular, toroidal, hot-plasma/ray-tracing code. First, the fractional power absorption of a ray during a single transit through the absorption layer is studied in a D-T plasma indicating total absorption in all INTOR cases except during the initial state characterized by low plasma temperature and density. However, in this case the single-pass wave absorption can be increased considerably by adding a few per cent of hydrogen. Further, complete power deposition profiles and Poynting vector distributions are presented for 'symmetric' and 'antisymmetric' 2x2 antenna array configurations with ksub(parallel)-shaping. Excitation of coaxial modes has, for the first time, been demonstrated explicitly by analysis of the Poynting vector distribution in real space. An antenna configuration with a π-phasing in the z-direction (such that the radiated power spectrum peaks at ksub(parallel) approx.= 5 m -1 ) and the choice of 3lambda/4 long antenna elements with 'symmetric' excitation in the y-direction, are found to produce central RF power deposition profiles in the second-harmonic and minority heating of INTOR. Finally, from a comparison of results for circular and non-circular NET/INTOR plasmas with elongation kappa=1.6, it is found that in the latter wave focusing is greatly reduced and that the power density figures are lower by approximately a factor of 1.9 for the case treated. (author)

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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

  6. Single-crystalline AlN growth on sapphire using physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas-Valencia, Andres M., E-mail: andres.cardenas@sri.co [SRI International (United States); Onishi, Shinzo; Rossie, Benjamin [SRI International (United States)

    2011-02-07

    A novel technique for growing single crystalline aluminum nitride (AlN) films is presented. The novelty of the technique, specifically, comes from the use of an innovative physical vapor deposition magnetron sputtering tool, which embeds magnets into the target material. A relatively high deposition rates is achieved ({approx}0.2 {mu}m/min), at temperatures between 860 and 940 {sup o}C. The AlN, grown onto sapphire, is single-crystalline as evidenced by observation using transmission electron microscopy. Tool configuration and growth conditions are discussed, as well as a first set of other analytical results, namely, x-ray diffraction and ultraviolet-visible transmission spectrophotometry.

  7. Understanding the reaction kinetics to optimize graphene growth on Cu by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Juergen; Boebel, Lena; Zwaschka, Gregor; Guenther, Sebastian [Technische Universitaet Muenchen, Zentralinstitut fuer Katalyseforschung, Chemie Department, Physikalische Chemie mit Schwerpunkt Katalyse, Garching (Germany)

    2017-11-15

    Understanding and controlling the growth kinetics of graphene is a prerequisite to synthesize this highly wanted material by chemical vapor deposition on Cu, e.g. for the construction of ultra-stable electron transparent membranes. It is reviewed that Cu foils contain a considerable amount of carbon in the bulk which significantly exceeds the expected amount of thermally equilibrated dissolved carbon in Cu and that this carbon must be removed before any high quality graphene may be grown. Starting with such conditioned Cu foils, systematic studies of the graphene growth kinetics in a reactive CH{sub 4}/H{sub 2} atmosphere allow to extract the following meaningful data: prediction of the equilibrium constant of the graphene formation reaction within a precision of a factor of two, the confirmation that the graphene growth proceeds from a C(ad)-phase on Cu which is in thermal equilibrium with the reactive gas phase, its apparent activation barrier and finally the prediction of the achievable growth velocity of the growing graphene flakes during chemical vapor deposition. As a result of the performed study, growth parameters are identified for the synthesis of high quality monolayer graphene with single crystalline domains of 100-1000 μm in diameter within a reasonable growth time. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Net protein and metabolizable protein requirements for maintenance and growth of early-weaned Dorper crossbred male lambs

    Institute of Scientific and Technical Information of China (English)

    Tao Ma; Kaidong Deng; Yan Tu; Naifeng Zhang; Bingwen Si; Guishan Xu; Qiyu Diao

    2017-01-01

    Background:Dorper is an important breed for meat purpose and widely used in the livestock industry of the world.However,the protein requirement of Dorper crossbred has not been investigated.The current paper reports the net protein (NP) and metabolizable protein (MP) requirements of Dorper crossbred ram lambs from 20 to 35 kg BW.Methods:Thirty-five Dorper × thin-tailed Han crossbred lambs weaned at approximately 50 d of age (20.3 ± 2.15 kg of BW) were used.Seven lambs of 25 kg BW were slaughtered as the baseline animals at the start of the trial.An intermediate group of seven randomly selected lambs fed ad libitum was slaughtered at 28.6 kg BW.The remaining 21 lambs were randomly divided into three levels of dry matter intake:ad libitum or 70% or 40% of ad libitum intake.Those lambs were slaughtered when the lambs fed ad libitum reached 35 kg BW.Total body N and N retention were measured.Results:The daily NP and MP requirements for maintenance were 1.89 and 4.52 g/kg metabolic shrunk BW (SBW0.75).The partial efficiency of MP utilization for maintenance was 0.42.The NP requirement for growth ranged from 12.1 to 43.5 g/d,for the lambs gaining 100 to 350 g/d,and the partial efficiency of MP utilization for growth was 0.86.Conclusions:The NP and MP requirements for the maintenance and growth of Dorper crossbred male lambs were lower than the recommendations of American and British nutritional systems.

  9. Comparisons of micrometeorology, growth of leather-fern [Rumohra adiantiformis, pteridophyta] and comfortable working environment between PO-film-covered and net-covered greenhouses in summer

    International Nuclear Information System (INIS)

    Yokoyama, H.; Harazono, Y.

    2004-01-01

    Protected cultivation of leather-fern in Hachijo-Island has been urged to prevent the Mottled Yellowing Syndrome (MYS) damage and to reduce the production costs. The purpose of the study was to reveal greenhouse environments that would provide good plant growth, a comfortable working environment and low-cost management, by comparing the micrometeorology and leatherfern productivity between Poly-Olefin (PO) film-covered greenhouses and the conventional netcovered greenhouses. Both greenhouses were fully covered by the same net. Field studies of leather-fern cultivation in Hachijo-Island showed that better productivity and quality of leather-fern have been provided by farmer's net-covered greenhouses than by farmer's PO-covered greenhouses. The light transmittance in the net-covered greenhouse was higher and the air temperature was lower than those in the PO-covered greenhouse. The comparative experiments using PO-covered greenhouses (PO), and net-covered greenhouses (NET), were conducted at the Hachijojima Horticultural Research Center. Air temperature and its vertical gradient in NET were lower than those in PO. Irrigation in PO was 225 mm during August and September in 1999, but 507 mm of precipitation in addition to the irrigation was supplied in NET. Air temperature and its vertical gradient in PO increased with solar radiation increase. Heat disorder in working environments for farmers did not occur in the NET, but several warning hours of heat disorder occurred in the PO as a dangerous working environment. The NET was thought to be a better system of leather-fern cultivation bringing about low costs and comfortable working environments. However, further application of fully rolled-up PO-film greenhouse system was recommended to control the soil water condition

  10. 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.

  11. Spiral growth of few-layer MoS{sub 2} by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dong, X.; Yan, C.; Tomer, D.; Li, L., E-mail: lianli@uwm.edu [Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53211 (United States); Li, C. H. [Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-08-01

    Growth spirals exhibit appealing properties due to a preferred layer stacking and lack of inversion symmetry. Here, we report spiral growth of MoS{sub 2} during chemical vapor deposition on SiO{sub 2}/Si and epitaxial graphene/SiC substrates, and their physical and electronic properties. We determine the layer-dependence of the MoS{sub 2} bandgap, ranging from 2.4 eV for the monolayer to a constant of 1.3 eV beyond the fifth layer. We further observe that spirals predominantly initiate at the step edges of the SiC substrate, based on which we propose a growth mechanism driven by screw dislocation created by the coalescence of two growth fronts at steps.

  12. Study of graphene growth on copper foil by pulsed laser deposition at reduced temperature

    Science.gov (United States)

    Abd Elhamid, Abd Elhamid M.; Hafez, Mohamed A.; Aboulfotouh, Abdelnaser M.; Azzouz, Iftitan M.

    2017-01-01

    Graphene has been successfully grown on commercial copper foil at low temperature of 500 °C by pulsed laser deposition (PLD). X-ray diffraction patterns showed that films have been grown in the presence of Cu(111) and Cu(200) facets. Raman spectroscopy was utilized to study the effects of temperature, surface structure, and cooling rate on the graphene growth. Raman spectra indicate that the synthesis of graphene layers rely on the surface quality of the Cu substrate together with the proper cooling profile coupled with graphene growth temperature. PLD-grown graphene film on Cu has been verified by transmission electron microscopy. Surface mediated growth of graphene on Cu foil substrate revealed to have a favorable catalytic effect. High growth rate of graphene and less defects can be derived using fast cooling rate.

  13. Growth responses of low-alpine dwarf-shrub heath species to nitrogen deposition and management

    International Nuclear Information System (INIS)

    Britton, Andrea J.; Fisher, Julia M.

    2008-01-01

    Nitrogen deposition is a continuing problem in European alpine regions. We hypothesised that, despite climatic limitations, low-alpine Calluna heathland would respond to nitrogen addition with increased shoot growth and flowering and that fire and grazing would modify responses. In a five-year study, 0-50 kg N ha -1 y -1 were added, combined with burning (+/-) and clipping (+/-). Calluna vulgaris responded with increased shoot extension, but effects on flowering were variable. Burning enhanced the positive effect of nitrogen addition and negative effects of clipping. Sub-dominant shrubs generally did not respond to nitrogen. C. vulgaris shoot extension was stimulated by nitrogen addition of 10 kg N ha -1 y -1 (above background) supporting suggestions that alpine heathlands are sensitive to low levels of nitrogen deposition. Increased C. vulgaris growth could negatively impact on important lichen components of this vegetation through increased shading and competition. Climatic factors constrain productivity in this community, but do not prevent rapid responses to nitrogen deposition by some species. - Low levels of N deposition increase productivity in alpine dwarf-shrub heath despite strong climatic constraints

  14. Nucleation and growth of microdroplets of ionic liquids deposited by physical vapor method onto different surfaces

    Science.gov (United States)

    Costa, José C. S.; Coelho, Ana F. S. M. G.; Mendes, Adélio; Santos, Luís M. N. B. F.

    2018-01-01

    Nanoscience and technology has generated an important area of research in the field of properties and functionality of ionic liquids (ILs) based materials and their thin films. This work explores the deposition process of ILs droplets as precursors for the fabrication of thin films, by means of physical vapor deposition (PVD). It was found that the deposition (by PVD on glass, indium tin oxide, graphene/nickel and gold-coated quartz crystal surfaces) of imidazolium [C4mim][NTf2] and pyrrolidinium [C4C1Pyrr][NTf2] based ILs generates micro/nanodroplets with a shape, size distribution and surface coverage that could be controlled by the evaporation flow rate and deposition time. No indication of the formation of a wetting-layer prior to the island growth was found. Based on the time-dependent morphological analysis of the micro/nanodroplets, a simple model for the description of the nucleation process and growth of ILs droplets is presented. The proposed model is based on three main steps: minimum free area to promote nucleation; first order coalescence; second order coalescence.

  15. Growth of highly oriented carbon nanotubes by plasma-enhanced hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.P.; Xu, J.W.; Ren, Z.F.; Wang, J.H. [Materials Synthesis Laboratory, Departments of Physics and Chemistry, and Center for Advanced Photonic and Electronic Materials (CAPEM), State University of New York at Buffalo, Buffalo, New York 14260 (United States); Siegal, M.P.; Provencio, P.N. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)

    1998-12-01

    Highly oriented, multiwalled carbon nanotubes were grown on polished polycrystalline and single crystal nickel substrates by plasma enhanced hot filament chemical vapor deposition at temperatures below 666 {degree}C. The carbon nanotubes range from 10 to 500 nm in diameter and 0.1 to 50 {mu}m in length depending on growth conditions. Acetylene is used as the carbon source for the growth of the carbon nanotubes and ammonia is used for dilution gas and catalysis. The plasma intensity, acetylene to ammonia gas ratio, and their flow rates, etc. affect the diameters and uniformity of the carbon nanotubes. {copyright} {ital 1998 American Institute of Physics.}

  16. Time variant layer control in atmospheric pressure chemical vapor deposition based growth of graphene

    KAUST Repository

    Qaisi, Ramy M.; Smith, Casey; Hussain, Muhammad Mustafa

    2013-01-01

    Graphene is a semi-metallic, transparent, atomic crystal structure material which is promising for its high mobility, strength and transparency - potentially applicable for radio frequency (RF) circuitry and energy harvesting and storage applications. Uniform (same number of layers), continuous (not torn or discontinuous), large area (100 mm to 200 mm wafer scale), low-cost, reliable growth are the first hand challenges for its commercialization prospect. We show a time variant uniform (layer control) growth of bi- to multi-layer graphene using atmospheric chemical vapor deposition system. We use Raman spectroscopy for physical characterization supported by electrical property analysis. © 2013 IEEE.

  17. Time variant layer control in atmospheric pressure chemical vapor deposition based growth of graphene

    KAUST Repository

    Qaisi, Ramy M.

    2013-04-01

    Graphene is a semi-metallic, transparent, atomic crystal structure material which is promising for its high mobility, strength and transparency - potentially applicable for radio frequency (RF) circuitry and energy harvesting and storage applications. Uniform (same number of layers), continuous (not torn or discontinuous), large area (100 mm to 200 mm wafer scale), low-cost, reliable growth are the first hand challenges for its commercialization prospect. We show a time variant uniform (layer control) growth of bi- to multi-layer graphene using atmospheric chemical vapor deposition system. We use Raman spectroscopy for physical characterization supported by electrical property analysis. © 2013 IEEE.

  18. Unraveling the growth of vertically aligned multi-walled carbon nanotubes by chemical vapor deposition

    International Nuclear Information System (INIS)

    Ramirez, A; Royo, C; Latorre, N; Mallada, R; Monzón, A; Tiggelaar, R M

    2014-01-01

    The interaction between the main operational variables during the growth of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) by catalytic chemical vapor deposition is studied. In this contribution, we report the influence of the carbon source (i.e. acetylene, ethylene and propylene), the reaction/activation temperature, the rate of heating, the reaction time, the metal loading, and the metallic nanoparticle size and distribution on the growth and alignment of carbon nanotubes. Fe/Al thin films deposited onto silicon samples by electron-beam evaporation are used as catalyst. A phenomenological growth mechanism is proposed to explain the interaction between these multiple factors. Three different outcomes of the synthesis process are found: i) formation of forests of non-aligned, randomly oriented multi-walled carbon nanotubes, ii) growth of vertically aligned tubes with a thin and homogeneous carbonaceous layer on the top, and iii) formation of vertically aligned carbon nanotubes. This carbonaceous layer (ii) has not been reported before. The main requirements to promote vertically aligned carbon nanotube growth are determined. (paper)

  19. Plasma effects in aligned carbon nanoflake growth by plasma-enhanced hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Zheng, K. [Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Cheng, Q.J., E-mail: qijin.cheng@xmu.edu.cn [School of Energy Research, Xiamen University, Xiamen 361005 (China); Ostrikov, K. [Plasma Nanoscience Center Australia (PNCA), Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organization, PO Box 218, Lindfield 2070, NSW (Australia); Institute for Future Environments and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, QLD (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney 2006, NSW (Australia)

    2015-01-15

    Highlights: • Plasma-specific effects in the growth of carbon nanoflakes (CNFs) are studied. • Electic field in the plasma sheath promotes separation of CNFs from the substrate. • The orentention of GNFs is related to the combined electic force and growth effects. • The high growth grates of aligned GNFs are plasma-related. - Abstract: Carbon nanofilms are directly grown on silicon substrates by plasma-enhanced hot filament chemical vapor deposition in methane environment. It is shown that the nanofilms are composed of aligned carbon nanoflakes by extensive investigation of experimental results of field emission scanning electron microscopy, micro-Raman spectroscopy and transmission electron microscopy. In comparison with the graphene-like films grown without plasmas, the carbon nanoflakes grow in an alignment mode and the growth rate of the films is increased. The effects of the plasma on the growth of the carbon nanofilms are studied. The plasma plays three main effects of (1) promoting the separation of the carbon nanoflakes from the silicon substrate, (2) accelerating the motion of hydrocarbon radicals, and (3) enhancing the deposition of hydrocarbon ions onto the substrate surface. Due to these plasma-specific effects, the carbon nanofilms can be formed from the aligned carbon nanoflakes with a high rate. These results advance our knowledge on the synthesis, properties and applications of graphene-based materials.

  20. Chemical vapour deposition growth and Raman characterization of graphene layers and carbon nanotubes

    Science.gov (United States)

    Lai, Y.-C.; Rafailov, P. M.; Vlaikova, E.; Marinova, V.; Lin, S. H.; Yu, P.; Yu, S.-C.; Chi, G. C.; Dimitrov, D.; Sveshtarov, P.; Mehandjiev, V.; Gospodinov, M. M.

    2016-02-01

    Single-layer graphene films were grown by chemical vapour deposition (CVD) on Cu foil. The CVD process was complemented by plasma enhancement to grow also vertically aligned multiwalled carbon nanotubes using Ni nanoparticles as catalyst. The obtained samples were characterized by Raman spectroscopy analysis. Nature of defects in the samples and optimal growth conditions leading to achieve high quality of graphene and carbon nanotubes are discussed.

  1. Synthesis, deposition and crystal growth of CZTS nanoparticles onto ceramic tiles

    Directory of Open Access Journals (Sweden)

    Ivan Calvet

    2015-09-01

    Full Text Available The work presents a simple solvothermal method for CZTS nanoparticles preparation using hexadecylamine (HDA as a capping agent. The as-prepared CZTS powder was deposited as ink using Doctor Blade technique onto ceramic tile, as a substrate substituting the typical soda-lime glass. The as-prepared film was thermal treated at different temperatures in order to enhance the thin film crystallinity. CZTS crystal growth onto ceramic tile was obtained successfully for the first time.

  2. Rapid and highly efficient growth of graphene on copper by chemical vapor deposition of ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Lisi, Nicola, E-mail: nicola.lisi@enea.it [ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome (Italy); Buonocore, Francesco; Dikonimos, Theodoros; Leoni, Enrico [ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome (Italy); Faggio, Giuliana; Messina, Giacomo [Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Università “Mediterranea” di Reggio Calabria, 89122 Reggio Calabria (Italy); Morandi, Vittorio; Ortolani, Luca [CNR-IMM Bologna, Via Gobetti 101, 40129 Bologna (Italy); Capasso, Andrea [ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome (Italy)

    2014-11-28

    The growth of graphene by chemical vapor deposition on metal foils is a promising technique to deliver large-area films with high electron mobility. Nowadays, the chemical vapor deposition of hydrocarbons on copper is the most investigated synthesis method, although many other carbon precursors and metal substrates are used too. Among these, ethanol is a safe and inexpensive precursor that seems to offer favorable synthesis kinetics. We explored the growth of graphene on copper from ethanol, focusing on processes of short duration (up to one min). We investigated the produced films by electron microscopy, Raman and X-ray photoemission spectroscopy. A graphene film with high crystalline quality was found to cover the entire copper catalyst substrate in just 20 s, making ethanol appear as a more efficient carbon feedstock than methane and other commonly used precursors. - Highlights: • Graphene films were grown by fast chemical vapor deposition of ethanol on copper. • High-temperature/short-time growth produced highly crystalline graphene. • The copper substrate was entirely covered by a graphene film in just 20 s. • Addition of H{sub 2} had a negligible effect on the crystalline quality.

  3. 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

  4. 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

  5. A systematic study of atmospheric pressure chemical vapor deposition growth of large-area monolayer graphene.

    Science.gov (United States)

    Liu, Lixin; Zhou, Hailong; Cheng, Rui; Chen, Yu; Lin, Yung-Chen; Qu, Yongquan; Bai, Jingwei; Ivanov, Ivan A; Liu, Gang; Huang, Yu; Duan, Xiangfeng

    2012-01-28

    Graphene has attracted considerable interest as a potential material for future electronics. Although mechanical peel is known to produce high quality graphene flakes, practical applications require continuous graphene layers over a large area. The catalyst-assisted chemical vapor deposition (CVD) is a promising synthetic method to deliver wafer-sized graphene. Here we present a systematic study on the nucleation and growth of crystallized graphene domains in an atmospheric pressure chemical vapor deposition (APCVD) process. Parametric studies show that the mean size of the graphene domains increases with increasing growth temperature and CH 4 partial pressure, while the density of domains decreases with increasing growth temperature and is independent of the CH 4 partial pressure. Our studies show that nucleation of graphene domains on copper substrate is highly dependent on the initial annealing temperature. A two-step synthetic process with higher initial annealing temperature but lower growth temperature is developed to reduce domain density and achieve high quality full-surface coverage of monolayer graphene films. Electrical transport measurements demonstrate that the resulting graphene exhibits a high carrier mobility of up to 3000 cm 2 V -1 s -1 at room temperature.

  6. Direct Growth of Graphene on Silicon by Metal-Free Chemical Vapor Deposition

    Science.gov (United States)

    Tai, Lixuan; Zhu, Daming; Liu, Xing; Yang, Tieying; Wang, Lei; Wang, Rui; Jiang, Sheng; Chen, Zhenhua; Xu, Zhongmin; Li, Xiaolong

    2018-06-01

    The metal-free synthesis of graphene on single-crystal silicon substrates, the most common commercial semiconductor, is of paramount significance for many technological applications. In this work, we report the growth of graphene directly on an upside-down placed, single-crystal silicon substrate using metal-free, ambient-pressure chemical vapor deposition. By controlling the growth temperature, in-plane propagation, edge-propagation, and core-propagation, the process of graphene growth on silicon can be identified. This process produces atomically flat monolayer or bilayer graphene domains, concave bilayer graphene domains, and bulging few-layer graphene domains. This work would be a significant step toward the synthesis of large-area and layer-controlled, high-quality graphene on single-crystal silicon substrates. [Figure not available: see fulltext.

  7. Atomic layer deposition: an enabling technology for the growth of functional nanoscale semiconductors

    Science.gov (United States)

    Biyikli, Necmi; Haider, Ali

    2017-09-01

    In this paper, we present the progress in the growth of nanoscale semiconductors grown via atomic layer deposition (ALD). After the adoption by semiconductor chip industry, ALD became a widespread tool to grow functional films and conformal ultra-thin coatings for various applications. Based on self-limiting and ligand-exchange-based surface reactions, ALD enabled the low-temperature growth of nanoscale dielectric, metal, and semiconductor materials. Being able to deposit wafer-scale uniform semiconductor films at relatively low-temperatures, with sub-monolayer thickness control and ultimate conformality, makes ALD attractive for semiconductor device applications. Towards this end, precursors and low-temperature growth recipes are developed to deposit crystalline thin films for compound and elemental semiconductors. Conventional thermal ALD as well as plasma-assisted and radical-enhanced techniques have been exploited to achieve device-compatible film quality. Metal-oxides, III-nitrides, sulfides, and selenides are among the most popular semiconductor material families studied via ALD technology. Besides thin films, ALD can grow nanostructured semiconductors as well using either template-assisted growth methods or bottom-up controlled nucleation mechanisms. Among the demonstrated semiconductor nanostructures are nanoparticles, nano/quantum-dots, nanowires, nanotubes, nanofibers, nanopillars, hollow and core-shell versions of the afore-mentioned nanostructures, and 2D materials including transition metal dichalcogenides and graphene. ALD-grown nanoscale semiconductor materials find applications in a vast amount of applications including functional coatings, catalysis and photocatalysis, renewable energy conversion and storage, chemical sensing, opto-electronics, and flexible electronics. In this review, we give an overview of the current state-of-the-art in ALD-based nanoscale semiconductor research including the already demonstrated and future applications.

  8. 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.

  9. Saharan Dust Deposition May Affect Phytoplankton Growth in the Mediterranean Sea at Ecological Time Scales

    Science.gov (United States)

    Gallisai, Rachele; Peters, Francesc; Volpe, Gianluca; Basart, Sara; Baldasano, José Maria

    2014-01-01

    The surface waters of the Mediterranean Sea are extremely poor in the nutrients necessary for plankton growth. At the same time, the Mediterranean Sea borders with the largest and most active desert areas in the world and the atmosphere over the basin is subject to frequent injections of mineral dust particles. We describe statistical correlations between dust deposition over the Mediterranean Sea and surface chlorophyll concentrations at ecological time scales. Aerosol deposition of Saharan origin may explain 1 to 10% (average 5%) of seasonally detrended chlorophyll variability in the low nutrient-low chlorophyll Mediterranean. Most of the statistically significant correlations are positive with main effects in spring over the Eastern and Central Mediterranean, conforming to a view of dust events fueling needed nutrients to the planktonic community. Some areas show negative effects of dust deposition on chlorophyll, coinciding with regions under a large influence of aerosols from European origin. The influence of dust deposition on chlorophyll dynamics may become larger in future scenarios of increased aridity and shallowing of the mixed layer. PMID:25333783

  10. Growth of CoSi2 on Si(001) by reactive deposition epitaxy

    International Nuclear Information System (INIS)

    Lim, C.W.; Shin, C.-S.; Gall, D.; Zuo, J.M.; Petrov, I.; Greene, J.E.

    2005-01-01

    CaF 2 -structure CoSi 2 layers were formed on Si(001) by reactive deposition epitaxy (RDE) and compared with CoSi 2 layers obtained by conventional solid phase growth (SPG). In both sets of experiments, Co was deposited by ultrahigh-vacuum magnetron sputtering and CoSi 2 formed at 600 deg. C. However, in the case of RDE, CoSi 2 formation occurred during Co deposition while for SPG, Co was deposited at 25 deg. C and silicidation took place during subsequent annealing. X-ray diffraction pole figures and transmission electron microscopy results demonstrate that RDE CoSi 2 layers are epitaxial with a cube-on-cube relationship (001) CoSi 2 parallel (001) Si and [100] CoSi 2 parallel[100] Si . In contrast, SPG films are polycrystalline with an average grain size of ≅1000 A and a mixed 111/002/022/112 orientation. We attribute the striking difference to rapid Co diffusion into the Si(001) substrate during RDE for which the high Co/Si reactivity gives rise to a flux-limited reaction resulting in the direct formation of the disilicide phase. In contrast, sequential nucleation and transformation among increasingly Si-rich phases--from orthorhombic Co 2 Si to cubic CoSi to CoSi 2 --during SPG results in polycrystalline layers with a complex texture

  11. 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.

  12. Bismuth nanowire growth under low deposition rate and its ohmic contact free of interface damage

    Directory of Open Access Journals (Sweden)

    Ye Tian

    2012-03-01

    Full Text Available High quality bismuth (Bi nanowire and its ohmic contact free of interface damage are quite desired for its research and application. In this paper, we propose one new way to prepare high-quality single crystal Bi nanowires at a low deposition rate, by magnetron sputtering method without the assistance of template or catalyst. The slow deposition growth mechanism of Bi nanowire is successfully explained by an anisotropic corner crossing effect, which is very different from existing explanations. A novel approach free of interface damage to ohmic contact of Bi nanowire is proposed and its good electrical conductivity is confirmed by I-V characteristic measurement. Our method provides a quick and convenient way to produce high-quality Bi nanowires and construct ohmic contact for desirable devices.

  13. The Net Carbon Flux due to Deforestation and Forest Re-Growth in the Brazilian Amazon: Analysis using a Process-Based Model

    Science.gov (United States)

    Hirsch, A. I.; Little, W. S.; Houghton, R. A.; Scott, N. A.; White, J. D.

    2004-01-01

    We developed a process-based model of forest growth, carbon cycling, and land cover dynamics named CARLUC (for CARbon and Land Use Change) to estimate the size of terrestrial carbon pools in terra firme (non-flooded) forests across the Brazilian Legal Amazon and the net flux of carbon resulting from forest disturbance and forest recovery from disturbance. Our goal in building the model was to construct a relatively simple ecosystem model that would respond to soil and climatic heterogeneity that allows us to study of the impact of Amazonian deforestation, selective logging, and accidental fire on the global carbon cycle. This paper focuses on the net flux caused by deforestation and forest re-growth over the period from 1970-1998. We calculate that the net flux to the atmosphere during this period reached a maximum of approx. 0.35 PgC/yr (1PgC = 1 x 10(exp I5) gC) in 1990, with a cumulative release of approx. 7 PgC from 1970- 1998. The net flux is higher than predicted by an earlier study by a total of 1 PgC over the period 1989-1 998 mainly because CARLUC predicts relatively high mature forest carbon storage compared to the datasets used in the earlier study. Incorporating the dynamics of litter and soil carbon pools into the model increases the cumulative net flux by approx. 1 PgC from 1970-1998, while different assumptions about land cover dynamics only caused small changes. The uncertainty of the net flux, calculated with a Monte-Carlo approach, is roughly 35% of the mean value (1 SD).

  14. 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.

  15. Patterned growth of carbon nanotubes obtained by high density plasma chemical vapor deposition

    Science.gov (United States)

    Mousinho, A. P.; Mansano, R. D.

    2015-03-01

    Patterned growth of carbon nanotubes by chemical vapor deposition represents an assembly approach to place and orient nanotubes at a stage as early as when they are synthesized. In this work, the carbon nanotubes were obtained at room temperature by High Density Plasmas Chemical Vapor Deposition (HDPCVD) system. This CVD system uses a new concept of plasma generation, where a planar coil coupled to an RF system for plasma generation was used with an electrostatic shield for plasma densification. In this mode, high density plasmas are obtained. We also report the patterned growth of carbon nanotubes on full 4-in Si wafers, using pure methane plasmas and iron as precursor material (seed). Photolithography processes were used to pattern the regions on the silicon wafers. The carbon nanotubes were characterized by micro-Raman spectroscopy, the spectra showed very single-walled carbon nanotubes axial vibration modes around 1590 cm-1 and radial breathing modes (RBM) around 120-400 cm-1, confirming that high quality of the carbon nanotubes obtained in this work. The carbon nanotubes were analyzed by atomic force microscopy and scanning electron microscopy too. The results showed that is possible obtain high-aligned carbon nanotubes with patterned growth on a silicon wafer with high reproducibility and control.

  16. Heteroepitaxial growth of 3-5 semiconductor compounds by metal-organic chemical vapor deposition for device applications

    Science.gov (United States)

    Collis, Ward J.; Abul-Fadl, Ali

    1988-01-01

    The purpose of this research is to design, install and operate a metal-organic chemical vapor deposition system which is to be used for the epitaxial growth of 3-5 semiconductor binary compounds, and ternary and quaternary alloys. The long-term goal is to utilize this vapor phase deposition in conjunction with existing current controlled liquid phase epitaxy facilities to perform hybrid growth sequences for fabricating integrated optoelectronic devices.

  17. Hydroxyapatite growth induced by native extracellular matrix deposition on solid surfaces

    Directory of Open Access Journals (Sweden)

    Pramatarova L.

    2005-02-01

    Full Text Available Biological systems have a remarkable capability to produce perfect fine structures such as seashells, pearls, bones, teeth and corals. These structures are composites of interacting inorganic (calcium phosphate or carbonate minerals and organic counterparts. It is difficult to say with certainty which part has the primary role. For example, the growth of molluscan shell crystals is thought to be initiated from a solution by the extracellular organic matrix (ECM. According to this theory, the matrix induces nucleation of calcium containing crystals. Recently, an alternative theory has been put forward, stating that a class of granulocytic hemocytes would be directly involved in shell crystal production in oysters. In the work presented here the surface of AISI 316 stainless steel was modified by deposition of ECM proteins. The ability of the modified substrates to induce nucleation and growth of hydroxyapatite (HA from simulated body fluid (SBF was examined by a kinetic study using two methods: (1 a simple soaking process in SBF and (2 a laser-liquid-solid interaction (LLSI process which allows interaction between a scanning laser beam and a solid substrate immersed in SBF. The deposited HA layers were investigated by Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM. It was found that a coating of stainless steel surface with native ECM proteins induced nucleation and growth of HA and facilitated its crystallization. By the process of simple soaking of the samples, irrespective of their horizontal or vertical position in the solution, HA layers were grown due to the reactive ECM-coated stainless steel surface. It was shown that the process occurring in the first stages of the growth was not only a result of the force of gravity. The application of the LLSI process strongly influenced HA formation on the ECM-modified substrates by promoting and enhancing the HA nucleation and growth through a synergistic effect

  18. Flow-dependent directional growth of carbon nanotube forests by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeongkeun; Park, Young Chul; Chun, Kyoung-Yong; Kim, Young-Jin; Choi, Jae-Boong [School of Mechanical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Kim, Keun Soo; Kang, Junmo; Hong, Byung Hee [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Boo, Jin-Hyo, E-mail: byunghee@skku.edu, E-mail: boong33@skku.edu [Department of Chemistry, RIAN and Institute of Basic Science, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of)

    2011-03-04

    We demonstrated that the structural formation of vertically aligned carbon nanotube (CNT) forests is primarily affected by the geometry-related gas flow, leading to the change of growth directions during the chemical vapor deposition (CVD) process. By varying the growing time, flow rate, and direction of the carrier gas, the structures and the formation mechanisms of the vertically aligned CNT forests were carefully investigated. The growth directions of CNTs are found to be highly dependent on the nonlinear local gas flows induced by microchannels. The angle of growth significantly changes with increasing gas flows perpendicular to the microchannel, while the parallel gas flow shows almost no effect. A computational fluid dynamics (CFD) model was employed to explain the flow-dependent growth of CNT forests, revealing that the variation of the local pressure induced by microchannels is an important parameter determining the directionality of the CNT growth. We expect that the present method and analyses would provide useful information to control the micro- and macrostructures of vertically aligned CNTs for various structural/electrical applications.

  19. Flow-dependent directional growth of carbon nanotube forests by chemical vapor deposition

    International Nuclear Information System (INIS)

    Kim, Hyeongkeun; Park, Young Chul; Chun, Kyoung-Yong; Kim, Young-Jin; Choi, Jae-Boong; Kim, Keun Soo; Kang, Junmo; Hong, Byung Hee; Boo, Jin-Hyo

    2011-01-01

    We demonstrated that the structural formation of vertically aligned carbon nanotube (CNT) forests is primarily affected by the geometry-related gas flow, leading to the change of growth directions during the chemical vapor deposition (CVD) process. By varying the growing time, flow rate, and direction of the carrier gas, the structures and the formation mechanisms of the vertically aligned CNT forests were carefully investigated. The growth directions of CNTs are found to be highly dependent on the nonlinear local gas flows induced by microchannels. The angle of growth significantly changes with increasing gas flows perpendicular to the microchannel, while the parallel gas flow shows almost no effect. A computational fluid dynamics (CFD) model was employed to explain the flow-dependent growth of CNT forests, revealing that the variation of the local pressure induced by microchannels is an important parameter determining the directionality of the CNT growth. We expect that the present method and analyses would provide useful information to control the micro- and macrostructures of vertically aligned CNTs for various structural/electrical applications.

  20. Equilibrium chemical vapor deposition growth of Bernal-stacked bilayer graphene.

    Science.gov (United States)

    Zhao, Pei; Kim, Sungjin; Chen, Xiao; Einarsson, Erik; Wang, Miao; Song, Yenan; Wang, Hongtao; Chiashi, Shohei; Xiang, Rong; Maruyama, Shigeo

    2014-11-25

    Using ethanol as the carbon source, self-limiting growth of AB-stacked bilayer graphene (BLG) has been achieved on Cu via an equilibrium chemical vapor deposition (CVD) process. We found that during this alcohol catalytic CVD (ACCVD) a source-gas pressure range exists to break the self-limitation of monolayer graphene on Cu, and at a certain equilibrium state it prefers to form uniform BLG with a high surface coverage of ∼94% and AB-stacking ratio of nearly 100%. More importantly, once the BLG is completed, this growth shows a self-limiting manner, and an extended ethanol flow time does not result in additional layers. We investigate the mechanism of this equilibrium BLG growth using isotopically labeled (13)C-ethanol and selective surface aryl functionalization, and results reveal that during the equilibrium ACCVD process a continuous substitution of graphene flakes occurs to the as-formed graphene and the BLG growth follows a layer-by-layer epitaxy mechanism. These phenomena are significantly in contrast to those observed for previously reported BLG growth using methane as precursor.

  1. The structure and growth mechanism of Si nanoneedles prepared by plasma-enhanced chemical vapor deposition

    Czech Academy of Sciences Publication Activity Database

    Červenka, Jiří; Ledinský, Martin; Stuchlík, Jiří; Stuchlíková, The-Ha; Bakardjieva, Snejana; Hruška, Karel; Fejfar, Antonín; Kočka, Jan

    2010-01-01

    Roč. 21, č. 41 (2010), 415604/1-415604/7 ISSN 0957-4484 R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR KAN400100701; GA MŠk LC510 EU Projects: European Commission(XE) 240826 - PolySiMode Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z40320502 Keywords : nanoneedles * nanowires * silicon * plasma * chemical vapor deposition * crystal structure * growth * phonon * SEM * Raman Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.644, year: 2010

  2. WATER QUALITY AND ITS EFFECT ON GROWTH AND SURVIVAL RATE OF LOBSTER REARED IN FLOATING NET CAGE IN EKAS BAY, WEST NUSA TENGGARA PROVINCE

    Directory of Open Access Journals (Sweden)

    Muhammad Junaidi

    2015-02-01

    Full Text Available ABSTRACT The development of lobster farming in floating net cage in Ekas Bay caused an environmental degradation such as decrease water quality due to some aquaculture wastes. The purposes of this study were to determine the status of water quality and their effect on growth and survival rate of lobster reared in floating net cages (FNC in the Ekas Bay, West Nusa Tenggara Province. Water sample collection and handling referred to the APHA (1992. Analyses of water quality data were conducted using Principal Component Analysis. Determination of the water quality status of Ekas Bay was performed with STORET system. Multivariate analyses were used to determine the relationship between water quality, growth, and survival rate of lobster reared in FNC. Results showed that Ekas Bay water quality status was categorized in class C (medium contaminated, which exceeded some quality standard parameters such as ammonia (0.3 mg/l, nitrate (0.008 mg/l, and phosphate (0.015 mg/l. During lobster farming activities feeding with trash fish for 270 days, we obtained daily growth rate of  0.74% (lower than normal growth rate of 0.86%, survival rate of 66% (lower than normal survival rate of 86.7%, and feed conversion ratio of 11.15. Ammonia was found as a dominant factor reducing growth  and survival rate of lobster reared in FNC. Keywords: water quality, lobsters, growth, survival, Ekas Bay

  3. 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

  4. A comparison of diamond growth rate using in-liquid and conventional plasma chemical vapor deposition methods

    International Nuclear Information System (INIS)

    Takahashi, Yoshiyuki; Toyota, Hiromichi; Nomura, Shinfuku; Mukasa, Shinobu; Inoue, Toru

    2009-01-01

    In order to make high-speed deposition of diamond effective, diamond growth rates for gas-phase microwave plasma chemical vapor deposition and in-liquid microwave plasma chemical vapor deposition are compared. A mixed gas of methane and hydrogen is used as the source gas for the gas-phase deposition, and a methanol solution of ethanol is used as the source liquid for the in-liquid deposition. The experimental system pressure is in the range of 60-150 kPa. While the growth rate of diamond increases as the pressure increases, the amount of input microwave energy per unit volume of diamond is 1 kW h/mm 3 regardless of the method used. Since the in-liquid deposition method provides a superior cooling effect through the evaporation of the liquid itself, a higher electric input power can be applied to the electrodes under higher pressure environments. The growth rate of in-liquid microwave plasma chemical vapor deposition process is found to be greater than conventional gas-phase microwave plasma chemical vapor deposition process under the same pressure conditions.

  5. A comparison of diamond growth rate using in-liquid and conventional plasma chemical vapor deposition methods

    Science.gov (United States)

    Takahashi, Yoshiyuki; Toyota, Hiromichi; Nomura, Shinfuku; Mukasa, Shinobu; Inoue, Toru

    2009-06-01

    In order to make high-speed deposition of diamond effective, diamond growth rates for gas-phase microwave plasma chemical vapor deposition and in-liquid microwave plasma chemical vapor deposition are compared. A mixed gas of methane and hydrogen is used as the source gas for the gas-phase deposition, and a methanol solution of ethanol is used as the source liquid for the in-liquid deposition. The experimental system pressure is in the range of 60-150 kPa. While the growth rate of diamond increases as the pressure increases, the amount of input microwave energy per unit volume of diamond is 1 kW h/mm3 regardless of the method used. Since the in-liquid deposition method provides a superior cooling effect through the evaporation of the liquid itself, a higher electric input power can be applied to the electrodes under higher pressure environments. The growth rate of in-liquid microwave plasma chemical vapor deposition process is found to be greater than conventional gas-phase microwave plasma chemical vapor deposition process under the same pressure conditions.

  6. Layered growth with bottom-spray granulation for spray deposition of drug.

    Science.gov (United States)

    Er, Dawn Z L; Liew, Celine V; Heng, Paul W S

    2009-07-30

    The gap in scientific knowledge on bottom-spray fluidized bed granulation has emphasized the need for more studies in this area. This paper comparatively studied the applicability of a modified bottom-spray process and the conventional top-spray process for the spray deposition of a micronized drug during granulation. The differences in circulation pattern, mode of growth and resultant granule properties between the two processes were highlighted. The more ordered and consistent circulation pattern of particles in a bottom-spray fluidized bed was observed to give rise to layered granule growth. This resulted in better drug content uniformity among the granule batches and within a granule batch. The processes' sensitivities to wetting and feed material characteristics were also compared and found to differ markedly. Less robustness to differing process conditions was observed for the top-spray process. The resultant bottom-spray granules formed were observed to be less porous, more spherical and had good flow properties. The bottom-spray technique can thus be potentially applied for the spray deposition of drug during granulation and was observed to be a good alternative to the conventional technique for preparing granules.

  7. H2-dependent attachment kinetics and shape evolution in chemical vapor deposition graphene growth

    Science.gov (United States)

    Meca, Esteban; Shenoy, Vivek B.; Lowengrub, John

    2017-09-01

    Experiments on graphene growth through chemical vapor deposition (CVD) involving methane (CH4) and hydrogen (H2) gases reveal a complex shape evolution and a non-monotonic dependence on the partial pressure of H2 ({{p}{{\\text{H}2}}} ). To explain these intriguing observations, we develop a microkinetic model for the stepwise decomposition of CH4 into mobile radicals and consider two possible mechanisms of attachment to graphene crystals: CH radicals to hydrogen-decorated edges of the crystals and C radicals to bare crystal edges. We derive an effective mass flux and an effective kinetic coefficient, both of which depend on {{p}{{\\text{H}2}}} , and incorporate these into a phase field model. The model reproduces both the non-monotonic dependence on {{p}{{\\text{H}2}}} and the characteristic shapes of graphene crystals observed in experiments. At small {{p}{{\\text{H}2}}} , growth is limited by the kinetics of attachment while at large {{p}{{\\text{H}2}}} growth is limited because the effective mass flux is small. We also derive a simple analytical model that captures the non-monotone behavior, enables the two mechanisms of attachment to be distinguished and provides guidelines for CVD growth of defect-free 2D crystals.

  8. 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.

  9. From atoms to layers: in situ gold cluster growth kinetics during sputter deposition

    Science.gov (United States)

    Schwartzkopf, Matthias; Buffet, Adeline; Körstgens, Volker; Metwalli, Ezzeldin; Schlage, Kai; Benecke, Gunthard; Perlich, Jan; Rawolle, Monika; Rothkirch, André; Heidmann, Berit; Herzog, Gerd; Müller-Buschbaum, Peter; Röhlsberger, Ralf; Gehrke, Rainer; Stribeck, Norbert; Roth, Stephan V.

    2013-05-01

    The adjustment of size-dependent catalytic, electrical and optical properties of gold cluster assemblies is a very significant issue in modern applied nanotechnology. We present a real-time investigation of the growth kinetics of gold nanostructures from small nuclei to a complete gold layer during magnetron sputter deposition with high time resolution by means of in situ microbeam grazing incidence small-angle X-ray scattering (μGISAXS). We specify the four-stage growth including their thresholds with sub-monolayer resolution and identify phase transitions monitored in Yoneda intensity as a material-specific characteristic. An innovative and flexible geometrical model enables the extraction of morphological real space parameters, such as cluster size and shape, correlation distance, layer porosity and surface coverage, directly from reciprocal space scattering data. This approach enables a large variety of future investigations of the influence of different process parameters on the thin metal film morphology. Furthermore, our study allows for deducing the wetting behavior of gold cluster films on solid substrates and provides a better understanding of the growth kinetics in general, which is essential for optimization of manufacturing parameters, saving energy and resources.The adjustment of size-dependent catalytic, electrical and optical properties of gold cluster assemblies is a very significant issue in modern applied nanotechnology. We present a real-time investigation of the growth kinetics of gold nanostructures from small nuclei to a complete gold layer during magnetron sputter deposition with high time resolution by means of in situ microbeam grazing incidence small-angle X-ray scattering (μGISAXS). We specify the four-stage growth including their thresholds with sub-monolayer resolution and identify phase transitions monitored in Yoneda intensity as a material-specific characteristic. An innovative and flexible geometrical model enables the extraction

  10. 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

  11. 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.

  12. The influence of cyclic deposition and anneal on growth of isolated and well-dispersed Au nanoisland arrays

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Li, Hao, E-mail: liha@missouri.edu

    2015-12-01

    Highlights: • Isolated and well-dispersed Au nanoislands were prepared by cyclical deposition and anneal. • The morphology of Au nanoislands were shown to be influenced by the number of growth cycles. • SERS sensing application was shown to be viable with as-prepared Au nanoislands. - Abstract: Isolated and well-dispersed Au nanoisland arrays were prepared with sputter deposition and post-deposition anneal in a cyclic fashion. Scanning electron microscopy (SEM) characterization and associated image analysis in aspects of nanoisland size, coverage, circularity, and density were performed to investigate the influence of cyclic deposition and anneal (DAA) on the morphology of as-prepared Au nanoisland arrays. This study revealed that, given a fixed amount of Au deposition per cycle, increasing the number of DAA cycles drove Au nanoislands’ gradual growth that was interpreted with the increase of their size and coverage and decrease of their density and circularity. In addition, given a fixed amount of total Au deposition, dividing the growth process into more cycles was shown to lower the growth rate of Au nanoislands. Moreover, the as-prepared Au nanoisland arrays were demonstrated to be a viable option as surface-enhanced Raman spectroscopy (SERS) sensing platform whose SERS enhancement was found to be highly dependent upon the size of nanoislands.

  13. The influence of cyclic deposition and anneal on growth of isolated and well-dispersed Au nanoisland arrays

    International Nuclear Information System (INIS)

    Sun, Xin; Li, Hao

    2015-01-01

    Highlights: • Isolated and well-dispersed Au nanoislands were prepared by cyclical deposition and anneal. • The morphology of Au nanoislands were shown to be influenced by the number of growth cycles. • SERS sensing application was shown to be viable with as-prepared Au nanoislands. - Abstract: Isolated and well-dispersed Au nanoisland arrays were prepared with sputter deposition and post-deposition anneal in a cyclic fashion. Scanning electron microscopy (SEM) characterization and associated image analysis in aspects of nanoisland size, coverage, circularity, and density were performed to investigate the influence of cyclic deposition and anneal (DAA) on the morphology of as-prepared Au nanoisland arrays. This study revealed that, given a fixed amount of Au deposition per cycle, increasing the number of DAA cycles drove Au nanoislands’ gradual growth that was interpreted with the increase of their size and coverage and decrease of their density and circularity. In addition, given a fixed amount of total Au deposition, dividing the growth process into more cycles was shown to lower the growth rate of Au nanoislands. Moreover, the as-prepared Au nanoisland arrays were demonstrated to be a viable option as surface-enhanced Raman spectroscopy (SERS) sensing platform whose SERS enhancement was found to be highly dependent upon the size of nanoislands.

  14. Petri Nets

    Indian Academy of Sciences (India)

    In a computer system, for example, typical discrete events ... This project brought out a series of influential reports on Petri net theory in the mid and late ... Technology became a leading centre for Petri net research and from then on, Petri nets ...

  15. Chemical vapor deposition growth of single-walled carbon nanotubes with controlled structures for nanodevice applications.

    Science.gov (United States)

    Chen, Yabin; Zhang, Jin

    2014-08-19

    Single-walled carbon nanotubes (SWNTs), a promising substitute to engineer prospective nanoelectronics, have attracted much attention because of their superb structures and physical properties. The unique properties of SWNTs rely sensitively on their specific chiral structures, including the diameters, chiral angles, and handedness. Furthermore, high-performance and integrated circuits essentially require SWNT samples with well-aligned arrays, of single conductive type and of pure chirality. Although much effort has been devoted to chemical vapor deposition (CVD) growth of SWNTs, their structure control, growth mechanism, and structural characterizations are still the primary obstacles for the fabrication and application of SWNT-based nanodevices. In this Account, we focus on our established CVD growth methodology to fulfill the requirements of nanodevice applications. A rational strategy was successfully exploited to construct complex architectures, selectively enrich semiconducting (s) or metallic (m) SWNTs, and control chirality. First, well-aligned and highly dense SWNT arrays are beneficial for nanodevice integration. For the directed growth mode, anisotropic interactions between the SWNTs and the crystallographic structure of substrate are crucial for their growth orientation. Just as crystals possess various symmetries, SWNTs with controlled geometries have the corresponding turning angles. Their complex architectures come from the synergetic effect of lattice and gas flow directed modes. Especially, the aligned orientations of SWNTs on graphite are chirality-selective, and their chiral angles, handedness, and (n,m) index have been conveniently and accurately determined. Second, UV irradiation and sodium dodecyl sulfate (SDS) washing-off methods have been explored to selectively remove m-SWNTs, leaving only s-SWNT arrays on the surface. Moreover, the UV-assisted technique takes the advantages of low cost and high efficiency and it directly produces a high

  16. High Yield Chemical Vapor Deposition Growth of High Quality Large-Area AB Stacked Bilayer Graphene

    Science.gov (United States)

    Liu, Lixin; Zhou, Hailong; Cheng, Rui; Yu, Woo Jong; Liu, Yuan; Chen, Yu; Shaw, Jonathan; Zhong, Xing; Huang, Yu; Duan, Xiangfeng

    2012-01-01

    Bernal stacked (AB stacked) bilayer graphene is of significant interest for functional electronic and photonic devices due to the feasibility to continuously tune its band gap with a vertical electrical field. Mechanical exfoliation can be used to produce AB stacked bilayer graphene flakes but typically with the sizes limited to a few micrometers. Chemical vapor deposition (CVD) has been recently explored for the synthesis of bilayer graphene but usually with limited coverage and a mixture of AB and randomly stacked structures. Herein we report a rational approach to produce large-area high quality AB stacked bilayer graphene. We show that the self-limiting effect of graphene growth on Cu foil can be broken by using a high H2/CH4 ratio in a low pressure CVD process to enable the continued growth of bilayer graphene. A high temperature and low pressure nucleation step is found to be critical for the formation of bilayer graphene nuclei with high AB stacking ratio. A rational design of a two-step CVD process is developed for the growth of bilayer graphene with high AB stacking ratio (up to 90 %) and high coverage (up to 99 %). The electrical transport studies demonstrated that devices made of the as-grown bilayer graphene exhibit typical characteristics of AB stacked bilayer graphene with the highest carrier mobility exceeding 4,000 cm2/V·s at room temperature, comparable to that of the exfoliated bilayer graphene. PMID:22906199

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-01

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

  18. Properties, synthesis, and growth mechanisms of carbon nanotubes with special focus on thermal chemical vapor deposition.

    Science.gov (United States)

    Nessim, Gilbert D

    2010-08-01

    Carbon nanotubes (CNTs) have been extensively investigated in the last decade because their superior properties could benefit many applications. However, CNTs have not yet made a major leap into industry, especially for electronic devices, because of fabrication challenges. This review provides an overview of state-of-the-art of CNT synthesis techniques and illustrates their major technical difficulties. It also charts possible in situ analyses and new reactor designs that might enable commercialization. After a brief description of the CNT properties and of the various techniques used to synthesize substrate-free CNTs, the bulk of this review analyzes chemical vapor deposition (CVD). This technique receives special attention since it allows CNTs to be grown in predefined locations, provides a certain degree of control of the types of CNTs grown, and may have the highest chance to succeed commercially. Understanding the primary growth mechanisms at play during CVD is critical for controlling the properties of the CNTs grown and remains the major hurdle to overcome. Various factors that influence CNT growth receive a special focus: choice of catalyst and substrate materials, source gases, and process parameters. This review illustrates important considerations for in situ characterization and new reactor designs that may enable researchers to better understand the physical growth mechanisms and to optimize the synthesis of CNTs, thus contributing to make carbon nanotubes a manufacturing reality.

  19. Fabrication and growth mechanism of carbon nanospheres by chemical vapor deposition

    International Nuclear Information System (INIS)

    Tian, F.; He, C.N.

    2010-01-01

    The synthesis of carbon nanospheres (CNSs) by chemical vapor deposition (CVD) of methane on catalyst of Ni-Al composite powders was reported. The influence factors on the growth morphology of CNSs, such as reaction temperature, reaction time and different carrier gases concerning hydrogen, nitrogen as well as no carrier gas were investigated using transmission electron microscope. The results showed that the reaction temperature had great effect on the structure of CNSs, higher temperature led to high-crystallized CNSs with high purity. The reaction time brought no significant influence to the structure of CNSs, but the average diameter of the CNSs was obviously increased with prolonging the reaction time. Relatively pure CNSs could be obtained with hydrogen as the carrier gas but with poor product rate compared with the CNSs with no carrier gas. Proper amount of CNSs with pure characteristic could be obtained with nitrogen as the carrier gas. Finally, a growth mechanism of dissolution-precipitation-diffusion is proposed for elucidating the growth process of general CNSs.

  20. 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

  1. 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.

  2. N sources affect growth, nutrient content, and net photosynthesis in maté (Ilex paraguariensis St. Hil.

    Directory of Open Access Journals (Sweden)

    Sérgio Gaiad

    2006-09-01

    Full Text Available The influence of different N sources on the growth of maté (Ilex paragurariensis St.Hil. seedlings grown in greenhouse was studied. All seedlings received a base fertilization of 10 mg N.kg-1 soil as NH4NO3, 60 mg P2O5.and 40 mg K2O.kg-1 soil as KH2PO4 15 days before treatments application. Treatments were as follow: Control, with no extra N added; Urea = 100 mg N.kg-1 soil as Urea; NO3- = 100 mg N.kg-1 soil as Ca(NO32; and NH4+ = 100 mg N.kg-1 soil as (NH42SO4. It was concluded that: 1 increasing N content in leaves alone was not able to promote gain in biomass production of maté seedlings; 2 seedlings receiving N-NH4 showed a higher accumulation of P and Mg on shoot biomass; and 3 an increase in leaf area, leaf number and net photosynthesis observed at the N-NH4 treatment was coincident with an increasing absorption of P and Mg.A influência de diferentes fontes de N sobre o crescimento de mudas de erva-mate (Ilex paraguariensis St.Hil. foi estudada, em casa de vegetação. Todas as mudas receberam uma fertilização base de 10 mg N.kg-1 de solo na forma de NH4NO3, 60 mg P2O5.kg-1 e 40 mg K2O.kg-1 de solo na forma de KH2PO4 quinze dias antes da aplicação dos tratamentos. Os tratamentos foram os seguintes: Controle, sem adição extra de N; Uréia = 100 mg N.kg-1 de solo como Uréia; NO3- = 100 mg N.kg-1 de solo como Ca(NO32; e NH4+ = 100 mg N.kg-1 de solo como (NH42SO4. Concluiu-se que: 1 o aumento do conteúdo de N nas folhas, por si, não é capaz de promover ganhos na produção de biomassa em mudas de erva-mate; 2 mudas que receberam N-NH4 apresentaram maior acumulo de P e Mg na biomassa aérea; e 3 o aumento na absorção de P e Mg coincidiu com um aumento na área foliar, no número de folhas e na fotossíntese liquida na fonte N-NH4.

  3. Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

    International Nuclear Information System (INIS)

    Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki; Kalita, Golap

    2014-01-01

    Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

  4. Laterally Stitched Heterostructures of Transition Metal Dichalcogenide: Chemical Vapor Deposition Growth on Lithographically Patterned Area

    KAUST Repository

    Li, Henan

    2016-10-31

    Two-dimensional transition metal dichalcogenides (TMDCs) have shown great promise in electronics and optoelectronics due to their unique electrical and optical properties. Heterostructured TMDC layers such as the laterally stitched TMDCs offer the advantages of better electronic contact and easier band offset tuning. Here, we demonstrate a photoresist-free focused ion beam (FIB) method to pattern as-grown TMDC monolayers by chemical vapor deposition, where the exposed edges from FIB etching serve as the seeds for growing a second TMDC material to form desired lateral heterostructures with arbitrary layouts. The proposed lithographic and growth processes offer better controllability for fabrication of the TMDC heterostrucuture, which enables the construction of devices based on heterostructural monolayers. © 2016 American Chemical Society.

  5. Growth and optical properties of Ag clusters deposited on poly(ethylene terephthalate)

    International Nuclear Information System (INIS)

    Flores-Camacho, J M; Weidlinger, G; Sun, L D; Hohage, M; Primetzhofer, D; Bauer, P; Zeppenfeld, P; Schmidegg, K

    2011-01-01

    The growth and concomitant evolution of the optical properties of Ag nano-clusters deposited on biaxially extruded poly(ethylene terephthalate) films is studied by reflectance difference spectroscopy. It is demonstrated by low energy ion scattering and simulated optical spectra that the clusters form a two-dimensional layer buried beneath the surface of the substrate. The experimental spectra are described by simulations in which different configurations of the host such as anisotropy, amorphization, and dilution are considered in an effective medium approach. The contribution of the anisotropic substrate is used to explain the resulting line shapes. We also discuss the role of the rate of change of the filling fraction with Ag coverage in the evolution of the spectra and the detection of the onset of coalescence by optical means.

  6. Growth of GaN micro/nanolaser arrays by chemical vapor deposition.

    Science.gov (United States)

    Liu, Haitao; Zhang, Hanlu; Dong, Lin; Zhang, Yingjiu; Pan, Caofeng

    2016-09-02

    Optically pumped ultraviolet lasing at room temperature based on GaN microwire arrays with Fabry-Perot cavities is demonstrated. GaN microwires have been grown perpendicularly on c-GaN/sapphire substrates through simple catalyst-free chemical vapor deposition. The GaN microwires are [0001] oriented single-crystal structures with hexagonal cross sections, each with a diameter of ∼1 μm and a length of ∼15 μm. A possible growth mechanism of the vertical GaN microwire arrays is proposed. Furthermore, we report room-temperature lasing in optically pumped GaN microwire arrays based on the Fabry-Perot cavity. Photoluminescence spectra exhibit lasing typically at 372 nm with an excitation threshold of 410 kW cm(-2). The result indicates that these aligned GaN microwire arrays may offer promising prospects for ultraviolet-emitting micro/nanodevices.

  7. LABORATORY EVALUATION OF ANDALIN, AN INSECT GROWTH REGULATOR INTERFERING WITH CUTICLE DEPOSITION, AGAINST MOSQUITO LARVAE

    Directory of Open Access Journals (Sweden)

    N REHIMI

    2002-12-01

    Full Text Available Andalin, a benzoylphenylurea (BPU derivative, was evaluated on Culex pipiens L. (Diptera: Culicidae. Treatment was made on newly 3rd- and 4th instar larvae for 24 h. The compound exhibited insecticidal activity and mortality occured after earlier inhibition of their development or by their inability to complete their ecdysis. Treatment resulted in a significant larvicidal effect and in a inhibition of adult emergence. Moreover, the compound disturbed growth and development since several morphological types and an increase in the duration of larval stage were observed. Histological study conducted on 4th instar larval integument, showed that Andalin caused a significant reduction in the thickness of cuticles secreted compared to controls. Thus, Andalin prevent molting in C. pipiens by interfering with cuticle deposition confirming the primary mode of action of this BPU insecticide.

  8. Growth of aligned ZnO nanowires via modified atmospheric pressure chemical vapor deposition

    International Nuclear Information System (INIS)

    Zhao, Yuping; Li, Chengchen; Chen, Mingming; Yu, Xiao; Chang, Yunwei; Chen, Anqi; Zhu, Hai; Tang, Zikang

    2016-01-01

    In this work, we report the growth of high-quality aligned ZnO nanowires via a facile atmospheric pressure chemical vapor deposition (CVD) method. The CVD reactor chamber used was more complicated than a conventional one due to the quartz boats loaded with sources (ZnO/C) and substrates being inserted into a semi-open quartz tube, and then placed inside the CVD reactor. The semi-open quartz tube played a very important role in growing the ZnO nanowires, and demonstrated that the transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber. Aligned ZnO nanowires were successfully obtained, though they were only found at substrates located upstream. The very high crystalline quality of the obtained ZnO nanowires was demonstrated by high-resolution transmission electron microscopy and room temperature photoluminescence investigations. Such ZnO nanowires with high crystalline quality may provide opportunities for the fabrication of ZnO-based nano-devices in future. - Highlights: • High-quality aligned ZnO nanowires were obtained via modified chemical vapor deposition under atmospheric pressure. • The semi-open quartz tube plays very important roles in growing ZnO nanowires. • The transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber.

  9. Growth of aligned ZnO nanowires via modified atmospheric pressure chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yuping; Li, Chengchen [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Chen, Mingming, E-mail: andychain@live.cn [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Yu, Xiao; Chang, Yunwei [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Chen, Anqi [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); Zhu, Hai, E-mail: zhuhai5@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); Tang, Zikang, E-mail: zktang@umac.mo [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); The Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau (China)

    2016-12-09

    In this work, we report the growth of high-quality aligned ZnO nanowires via a facile atmospheric pressure chemical vapor deposition (CVD) method. The CVD reactor chamber used was more complicated than a conventional one due to the quartz boats loaded with sources (ZnO/C) and substrates being inserted into a semi-open quartz tube, and then placed inside the CVD reactor. The semi-open quartz tube played a very important role in growing the ZnO nanowires, and demonstrated that the transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber. Aligned ZnO nanowires were successfully obtained, though they were only found at substrates located upstream. The very high crystalline quality of the obtained ZnO nanowires was demonstrated by high-resolution transmission electron microscopy and room temperature photoluminescence investigations. Such ZnO nanowires with high crystalline quality may provide opportunities for the fabrication of ZnO-based nano-devices in future. - Highlights: • High-quality aligned ZnO nanowires were obtained via modified chemical vapor deposition under atmospheric pressure. • The semi-open quartz tube plays very important roles in growing ZnO nanowires. • The transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber.

  10. Growth and characterization of polycrystalline Ge1-xCx by reactive pulsed laser deposition

    International Nuclear Information System (INIS)

    Hernandez, M.P.; Farias, M.H.; Castillon, F.F.; Diaz, Jesus A.; Avalos, M.; Ulloa, L.; Gallegos, J.A.; Yee-Madeiros, H.

    2011-01-01

    Polycrystalline thin films of Ge-C were grown on Si (1 1 1) substrates by means of reactive pulsed laser deposition with methane pressure of 100 mTorr. Effect substrate temperature, T s , on C incorporation to substitutional sites (x) in Ge 1-x C x was investigated systematically by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyzes. The substrate temperatures were ranging from 250 to 400 deg. C. The substitutional C composition x in the films by XRD were estimated using the Vegard's linear law. The maximum value of x calculated by XRD was 0.032 for T s of 350 deg. C. The position of the C 1s peak at 283.4 eV in the XPS spectrum confirmed the germanium-carbon alloys. XRD measurements indicated that x increased with T s from 250 deg. C to 350 deg. C. At T s = 400 deg. C, the estimation of x was lowered. However, the C content calculated by XPS analyzes increased with T s being more these values than substitutional C composition x. XPS and XRD analyzes demonstrate that the remaining C atoms are incorporated to interstitial sites. The use of the T s plays important roles in the incorporation of substitutional C and in restraining C-cluster formation in the reactive pulsed laser deposition growth of Ge-C/Si.

  11. ZnO crystal growth on microelectrode by electrochemical deposition method

    International Nuclear Information System (INIS)

    Kondo, Y; Ashida, A; Nouzu, N; Fujimura, N

    2011-01-01

    Zinc Oxide crystals were grown by constant potential electrochemical deposition method on the substrate with the Pt working electrode which consists of Pt film with large area and μm-sized line and space structured area. In case of depositions with cathodic potential of -0.3V, ZnO crystal is not observed on the micro electrode, but observed on the electrode with large area (0.2 cm 2 ). By using electrolyte with higher pH, ZnO crystal grows on both areas. In case of lower pH, ZnO crystal does not grow on either. From these results, the pH range for growth of ZnO on the microelectrode seems to be higher than that on the electrode with large area. And, it is expected that the pH just on the surface of μm-sized electrode is lower than that in the bulk of electrolyte. Based on these results, it can be concluded that control of the pH in vicinity of the surface is very important to ECD method for micro- and nano-scaled devices.

  12. Role of hydrogen in the chemical vapor deposition growth of MoS2 atomic layers

    Science.gov (United States)

    Li, Xiao; Li, Xinming; Zang, Xiaobei; Zhu, Miao; He, Yijia; Wang, Kunlin; Xie, Dan; Zhu, Hongwei

    2015-04-01

    Hydrogen plays a crucial role in the chemical vapor deposition (CVD) growth of graphene. Here, we have revealed the roles of hydrogen in the two-step CVD growth of MoS2. Our study demonstrates that hydrogen acts as the following: (i) an inhibitor of the thermal-induced etching effect in the continuous film growth process; and (ii) a promoter of the desulfurization reaction by decreasing the S/Mo atomic ratio and the oxidation reaction of the obtained MoSx (0 desulfurization reaction by decreasing the S/Mo atomic ratio and the oxidation reaction of the obtained MoSx (0 < x < 2) films. A high hydrogen content of more than 100% in argon forms nano-sized circle-like defects and damages the continuity and uniformity of the film. Continuous MoS2 films with a high crystallinity and a nearly perfect S/Mo atomic ratio were finally obtained after sulfurization annealing with a hydrogen content in the range of 20%-80%. This insightful understanding reveals the crucial roles of hydrogen in the CVD growth of MoS2 and paves the way for the controllable synthesis of two-dimensional materials. Electronic supplementary information (ESI) available: Low-magnification optical images; Raman spectra of 0% and 5% H2 samples; AFM characterization; Schematic of the film before and after sulfurization annealing; Schematic illustrations of two typical Raman-active phonon modes (E12g, A1g); Raman (mapping) spectra for 40% and 80% H2 samples before and after sulfurization annealing; PL spectra. See DOI: 10.1039/c5nr00904a

  13. 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.

  14. 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.

  15. The impact of atmospheric deposition and climate on forest growth in Europe using two empirical modelling approaches

    Science.gov (United States)

    Dobbertin, M.; Solberg, S.; Laubhann, D.; Sterba, H.; Reinds, G. J.; de Vries, W.

    2009-04-01

    Most recent studies show increasing forest growth in central Europe, rather than a decline as was expected due to negative effects of air pollution. While nitrogen deposition, increasing temperature and change in forest management are discussed as possible causes, quantification of the various environmental factors has rarely been undertaken. In our study, we used data from several hundreds of intensive monitoring plots from the ICP Forests network in Europe, ranging from northern Finland to Spain and southern Italy. Five-year growth data for the period 1994-1999 were available from roughly 650 plots to examine the influence of environmental factors on forest growth. Evaluations focused on the influence of nitrogen, sulphur and acid deposition, temperature, precipitation and drought. Concerning the latter meteorological variables we used the deviation from the long-term (30 years) mean. The study included the main tree species common beech (Fagus sylvatica), sessile or pedunculate oak (Quercus petraea and Q. robur), Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Two very different approaches were used. In the first approach an individual tree-based regression model was applied (Laubhahn et al., 2009), while in the second approach a stand-based model was applied (Solberg et al., 2009). The individual tree-based model had measured basal area increment of each individual tree as a growth response variable and tree size (diameter at breast height), tree competition (basal area of larger trees and stand density index), site factors (e.g. soil C/N ratio, temperature), and environmental factors (e.g. temperature change compared to long-term average, nitrogen and sulphur deposition) as influencing parameters. In the stand-growth model, stem volume increment was used as the growth response variable, after filtering out the expected growth. Expected growth was modelled as a function of site productivity, stand age and a stand density index. Relative volume

  16. Chemical vapor deposition growth of boron-carbon-nitrogen layers from methylamine borane thermolysis products

    Science.gov (United States)

    Leardini, Fabrice; Flores, Eduardo; Galvis E, Andrés R.; Ferrer, Isabel J.; Ramón Ares, José; Sánchez, Carlos; Molina, Pablo; van der Meulen, Herko P.; Gómez Navarro, Cristina; López Polin, Guillermo; Urbanos, Fernando J.; Granados, Daniel; García-García, F. Javier; Demirci, Umit B.; Yot, Pascal G.; Mastrangelo, Filippo; Grazia Betti, Maria; Mariani, Carlo

    2018-01-01

    This work investigates the growth of B-C-N layers by chemical vapor deposition using methylamine borane (MeAB) as the single-source precursor. MeAB has been synthesized and characterized, paying particular attention to the analysis of its thermolysis products, which are the gaseous precursors for B-C-N growth. Samples have been grown on Cu foils and transferred onto different substrates for their morphological, structural, chemical, electronic and optical characterizations. The results of these characterizations indicate a segregation of h-BN and graphene-like (Gr) domains. However, there is an important presence of B and N interactions with C at the Gr borders, and of C interacting at the h-BN-edges, respectively, in the obtained nano-layers. In particular, there is a significant presence of C-N bonds, at Gr/h-BN borders and in the form of N doping of Gr domains. The overall B:C:N contents in the layers is close to 1:3:1.5. A careful analysis of the optical bandgap determination of the obtained B-C-N layers is presented, discussed and compared with previous seminal works with samples of similar composition.

  17. 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.

  18. 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.

  19. Ge deposition on Si(1 0 0) in the conditions close to dynamic equilibrium between islands growth and their decay

    International Nuclear Information System (INIS)

    Shklyaev, A.A.; Budazhapova, A.E.

    2016-01-01

    Graphical abstract: - Highlights: • Solid source MBE is used for island growth by Ge deposition on Si(1 0 0) at 700–900 °C. • Islands acquire a monomodal size distribution at temperatures above 800 °C. • Islands form ordered arrays during Ge deposition at 900 °C. • Conditions close to dynamic equilibrium are realized for growth and decay of islands at 900 °C. • Shape of ordered islands is cone with shallow sidewalls. - Abstract: The formation of islands arrays during Ge deposition on Si(1 0 0) at high temperatures is studied using scanning tunneling and electron microscopies. It is found that the island size and shape distributions, which are known to be bimodal at growth temperatures below 700 °C, become monomodal at temperatures above 800 °C. The obtained data suggest that the processes such as island nucleation and Ostwald ripening become less significant in the surface morphology formation, giving the advantage to selective attachment of deposited Ge atoms to island sidewalls and spatially inhomogeneous Si-Ge intermixing, as the temperature increases. At 900 °C, the islands exhibit a tendency to form laterally ordered arrays when the growth conditions approach the dynamic equilibrium between the growth of islands and their decay by means of Si-Ge intermixing. The islands ordering is accompanied by their shape transformation into the cone with shallow sidewalls inclined from (1 0 0) by angles of around 10°.

  20. Synthesis and growth mechanism of Fe-catalyzed carbon nanotubes by plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Jiang Jun; Feng Tao; Cheng Xinhong; Dai Lijuan; Cao Gongbai; Jiang Bingyao; Wang Xi; Liu Xianghuai; Zou Shichang

    2006-01-01

    Plasma-enhanced chemical vapor deposition (PECVD) was used to grow Fe-catalyzed carbon nanotubes (CNTs). The nanotubes had a uniform diameter in the range of about 10-20 nm. A base growth mode was responsible for the CNTs growth using a mixture of H 2 (60 sccm) and C 2 H 2 (15 sccm). For a mixture of H 2 (100 sccm) and C 2 H 2 (25 sccm), a complicated growth mechanism took place involving both the base growth and the tip growth. X-ray photoelectron spectroscopy measurements revealed that the grown CNTs contained C-H covalent bonds and Fe-C bonds located at the interface between them and the substrates. The factors determining the growth mechanism of CNTs are discussed and their growth mechanisms with the different gas ratios are suggested

  1. Molecular dynamics study of growth and interface structure during aluminum deposition on Ni(1 0 0) substrate

    International Nuclear Information System (INIS)

    er, Laboratory of Radiation and Matter, Faculty of Science and Technology, 26000 Settat (Morocco); Univ Hassan 1er, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco))" data-affiliation=" (Univ Hassan 1er, Laboratory of Radiation and Matter, Faculty of Science and Technology, 26000 Settat (Morocco); Univ Hassan 1er, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco))" >Hassani, A.; Makan, A.; er, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco))" data-affiliation=" (Univ Hassan 1er, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco))" >Sbiaai, K.; er, Laboratory of Radiation and Matter, Faculty of Science and Technology, 26000 Settat (Morocco))" data-affiliation=" (Univ Hassan 1er, Laboratory of Radiation and Matter, Faculty of Science and Technology, 26000 Settat (Morocco))" >Tabyaoui, A.; er, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco))" data-affiliation=" (Univ Hassan 1er, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco))" >Hasnaoui, A.

    2015-01-01

    Highlights: • Aluminum thin film growth on Ni(1 0 0) substrate was investigated. • Molecular dynamics simulation based on EAM interaction potential was considered. • Hexagonal and fourfold structures coexisted in the first layer. • Interface mismatch was revealed by wavy effect occurring in both lateral directions. • Film growth followed a layer-by-layer mode only in the first three deposited layers. - Abstract: We investigate aluminum thin film growth on Ni(1 0 0) substrate by means of molecular dynamics simulation. Embedded Atom Method interaction potential is considered. The simulation is performed at 300 K using an incident energy of 1 eV. The substrate-grown film interface shows the coexistence of hexagonal and fourfold structures in the first layer during the initial stage of deposition. As the deposition proceeds, the hexagonal geometry transforms to fourfold one which becomes dominant toward the end of deposition. The coverage of this layer exceeded 100%. Moreover, the deposited Al atoms with fourfold geometry adopt the lattice parameter of Ni as the thickness of deposited film increases. The interface mismatch investigation revealed that the roughness is dictated by how the Al(1 1 1) fits to the Ni(1 0 0) substrate, which may be reflected by a wavy effect occurring in both lateral directions. Furthermore, the film grows by a layer-by-layer mode with a coverage rate greater than 66.7% in the first three layers, while it follows an island mode with a coverage rate lower than the previous value (66.7%) beyond the third layer. Overall, a detailed analysis of each layer growth has established a relationship between the number of deposited atoms and the coverage rate of each layer

  2. Validation of Growth Layer Group (GLG depositional rate using daily incremental growth lines in the dentin of beluga (Delphinapterus leucas (Pallas, 1776 teeth.

    Directory of Open Access Journals (Sweden)

    David A Waugh

    Full Text Available Counts of Growth Layer Groups (GLGs in the dentin of marine mammal teeth are widely used as indicators of age. In most marine mammals, observations document that GLGs are deposited yearly, but in beluga whales, some studies have supported the view that two GLGs are deposited each year. Our understanding of beluga life-history differs substantially depending on assumptions regarding the timing of GLG deposition; therefore, resolving this issue has important considerations for population assessments. In this study, we used incremental lines that represent daily pulses of dentin mineralization to test the hypothesis that GLGs in beluga dentin are deposited on a yearly basis. Our estimate of the number of daily growth lines within one GLG is remarkably close to 365 days within error, supporting the hypothesis that GLGs are deposited annually in beluga. We show that measurement of daily growth increments can be used to validate the time represented by GLGs in beluga. Furthermore, we believe this methodology may have broader applications to age estimation in other taxa.

  3. Multilayer graphene growth on polar dielectric substrates using chemical vapour deposition

    Science.gov (United States)

    Karamat, S.; Çelik, K.; Shah Zaman, S.; Oral, A.

    2018-06-01

    High quality of graphene is necessary for its applications at industrial scale production. The most convenient way is its direct growth on dielectrics which avoid the transfer route of graphene from metal to dielectric substrate usually followed by graphene community. The choice of a suitable dielectric for the gate material which can replace silicon dioxide (SiO2) is in high demand. Various properties like permittivity, thermodynamic stability, film morphology, interface quality, bandgap and band alignment of other dielectrics with graphene needs more exploration. A potential dielectric material is required which could be used to grow graphene with all these qualities. Direct growth of graphene on magnesium oxide (MgO) substrates is an interesting idea and will be a new addition in the library of 2D materials. The present work is about the direct growth of graphene on MgO substrates by an ambient pressure chemical vapour deposition (CVD) method. We address the surface instability issue of the polar oxides which is the most challenging factor in MgO. Atomic force microscopy (AFM) measurements showed the topographical features of the graphene coated on MgO. X-ray photoelectron spectroscopy (XPS) study is carried out to extract information regarding the presence of necessary elements, their bonding with substrates and to confirm the sp-2 hybridization of carbon, which is a characteristic feature of graphene film. The chemical shift is due to the surface reconstruction of MgO in the prepared samples. For graphene-MgO interface, valence band offset (VBO) and conduction band offset (CBO) extracted from valence band spectra reported. Further, we predicted the energy band diagram for single layer and thin film of graphene. By using the room-temperature energy band gap values of MgO and graphene, the CBO is calculated to be 6.85 eV for single layer and 5.66 eV for few layer (1-3) of graphene layers.

  4. Rapid growth of zinc oxide nanobars in presence of electric field by physical vapor deposition

    Science.gov (United States)

    Jouya, Mehraban; Taromian, Fahime; Siami, Simin

    2017-12-01

    In this contribution, electric field has some effects to increase growth for specific time duration on zinc oxide (ZnO) nanobars. First, the zinc (Zn) thin film has been prepared by 235,000 V/m electric field assisted physical vapor deposition (PVD) at vacuum of 1.33 × 10-5 mbar. Second, strong electric field of 134,000 V/m has been used in ambient for growing ZnO nanobars in term of the time include 2.5 and 10 h. The performances of the ZnO nanostructure in absence and presence of electric field have been determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of XRD analysis showed that ZnO has a hexagonal bars structure and a strongly preferred (101) orientation which is strongest than without applying electric field. SEM analysis revealed that physical vapored ZnO thin film in presence of electric field are densely packed with uniform morphological, thinner and denser in distribution. Electric field effect for ZnO growth in 2.5 h is better than it in the 2.5 h without electric field but by passing the time the media influence has good power almost as same as electric field. Through this electric field in PVD, the compact and uniform Zn film has been achieved which is less diameter than ordinary PVD method. Finally, we carry out a series of experiments to grow different-orientation ZnO nanobars with less than 100 nm in diameter, which are the time saving process in base of PVD ever reported. Therefore, the significant conclusion in usage electric field is reducing time of growth.

  5. The net acid extruders NHE1, NBCn1 and MCT4 promote mammary tumor growth through distinct but overlapping mechanisms

    DEFF Research Database (Denmark)

    Andersen, Anne Poder; Samsøe-Petersen, Jacob; Oernbo, Eva Kjer

    2018-01-01

    High metabolic and proliferative rates in cancer cells lead to production of large amounts of H+ and CO2 , and as a result, net acid extruding transporters are essential for the function and survival of cancer cells. We assessed protein expression of the Na+ /H+ exchanger NHE1, the Na+ - HCO3......- cotransporter NBCn1, and the lactate-H+ cotransporters MCT1 and -4 by immunohistochemical analysis of a large cohort of breast cancer samples. We found robust expression of these transporters in 20, 10, 4 and 11% of samples, respectively. NHE1 and NBCn1 expression both correlated positively with progesterone...

  6. Impact of cation stoichiometry on the early stage of growth of SrTiO{sub 3} deposited by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chencheng, E-mail: c.xu@fz-juelich.de; Moors, Marco; Dittmann, Regina

    2015-12-30

    Highlights: • Stoichiometry dependence of SrTiO{sub 3} sub-monolayer growth monitored by RHEED/AFM. • Reduced surface diffusion of non-stoichiometric SrTiO{sub 3} was detected. • A modified step density model correlates surface diffusion and RHEED minimum. - Abstract: By performing in situ growth studies during pulsed laser deposition, we observed a strong reduction of the surface diffusion coefficients for slightly non-stoichiometric SrTiO{sub 3}. Both, stoichiometric and non-stoichiometric thin films exhibit 2D layer by layer growth. However, in the non-stoichiometric case the 2D island coalescence is significantly delayed, which goes along with a shift of the reflection high electron energy diffraction (RHEED) minimum. We could explain this shift of the RHEED minimum by developing a model for the step density evolution taking into account finite surface diffusion.

  7. Growth of ZnO nanocrystals in silica by rf co-sputter deposition and post-annealing

    International Nuclear Information System (INIS)

    Siva Kumar, V.V.; Singh, F.; Kumar, Amit; Avasthi, D.K.

    2006-01-01

    Thin films with ZnO nanocrystals in silica were synthesized by rf reactive magnetron co-sputter deposition and post-annealing. The films were deposited from a ZnO/Si composite target in an rf oxygen plasma. The deposited films were annealed in air/vacuum at high temperatures to grow ZnO nanocrystals. The deposited and annealed films were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), uv-vis spectroscopy (UV-VIS) and photoluminescence (PL) measurements. FT-IR results of the films show the vibrational features of Si-O-Si and Zn-O bonds. UV-VIS spectra of the deposited film shows the band edge of ZnO. The XRD results of the films annealed at 750 deg. C and 1000 deg. C indicate the growth of ZnO nanocrystals with average crystallite sizes between 7 nm and 26 nm. PL measurements of the deposited film show a broad visible luminescence peak which can be due to ZnO. These results suggest the growth of ZnO nanocrystals in silica matrix

  8. Net Neutrality

    DEFF Research Database (Denmark)

    Savin, Andrej

    2017-01-01

    Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else.......Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else....

  9. Growth kinetics of nc-Si:H deposited at 200 °C by hot-wire chemical vapour deposition

    CSIR Research Space (South Africa)

    Oliphant, CJ

    2011-05-01

    Full Text Available deposited on single-side polished (100) crystalline silicon and Corning 7059 glass substrates using an ultra-high vacuum HWCVD system [3] from various 3 gas mixtures of SiH4 and H2. The H-dilution ratio, defined as )( 42 2 SiHH HR ?+? ? = , where..., South Africa 2 National Metrology Institute of South Africa, Private Bag X34, Lynwood Ridge, Pretoria 0040, South Africa 3 CSIR National Centre for Nano-Structured Materials, P. O. Box 395, Pretoria 0001, South Africa Abstract We report...

  10. Van der Waals epitaxial growth of MoS2 on SiO2/Si by chemical vapor deposition

    KAUST Repository

    Cheng, Yingchun

    2013-01-01

    Recently, single layer MoS2 with a direct band gap of 1.9 eV has been proposed as a candidate for two dimensional nanoelectronic devices. However, the synthetic approach to obtain high-quality MoS2 atomic thin layers is still problematic. Spectroscopic and microscopic results reveal that both single layers and tetrahedral clusters of MoS2 are deposited directly on the SiO2/Si substrate by chemical vapor deposition. The tetrahedral clusters are mixtures of 2H- and 3R-MoS2. By ex situ optical analysis, both the single layers and tetrahedral clusters can be attributed to van der Waals epitaxial growth. Due to the similar layered structures we expect the same growth mechanism for other transition-metal disulfides by chemical vapor deposition. © 2013 The Royal Society of Chemistry.

  11. Reduced-Pressure Chemical Vapor Deposition Growth of Isolated Ge Crystals and Suspended Layers on Micrometric Si Pillars.

    Science.gov (United States)

    Skibitzki, Oliver; Capellini, Giovanni; Yamamoto, Yuji; Zaumseil, Peter; Schubert, Markus Andreas; Schroeder, Thomas; Ballabio, Andrea; Bergamaschini, Roberto; Salvalaglio, Marco; Miglio, Leo; Montalenti, Francesco

    2016-10-05

    In this work, we demonstrate the growth of Ge crystals and suspended continuous layers on Si(001) substrates deeply patterned in high aspect-ratio pillars. The material deposition was carried out in a commercial reduced-pressure chemical vapor deposition reactor, thus extending the "vertical-heteroepitaxy" technique developed by using the peculiar low-energy plasma-enhanced chemical vapor deposition reactor, to widely available epitaxial tools. The growth process was thoroughly analyzed, from the formation of small initial seeds to the final coalescence into a continuous suspended layer, by means of scanning and transmission electron microscopy, X-ray diffraction, and μ-Raman spectroscopy. The preoxidation of the Si pillar sidewalls and the addition of hydrochloric gas in the reactants proved to be key to achieve highly selective Ge growth on the pillars top only, which, in turn, is needed to promote the formation of a continuous Ge layer. Thanks to continuum growth models, we were able to single out the different roles played by thermodynamics and kinetics in the deposition dynamics. We believe that our findings will open the way to the low-cost realization of tens of micrometers thick heteroepitaxial layer (e.g., Ge, SiC, and GaAs) on Si having high crystal quality.

  12. The effect of deposited fine sediment on summer survival and growth of rainbow trout in riffles of a small stream

    Science.gov (United States)

    Bret C. Harvey; Jason L. White; Rodney J. Nakamoto

    2009-01-01

    Elevated fine-sediment inputs to streams can alter a variety of conditions and processes, including the amount of fine sediment stored in riffles. We sought to measure the influence of deposited fine sediment on the survival and growth of juvenile rainbow trout Oncorhynchus mykiss (106–130 mm fork length) using a field experiment that included 18 enclosures in riffles...

  13. Assessing the impacts of climate change and nitrogen deposition on Norway spruce growth in Austria with BIOME-BGC

    Energy Technology Data Exchange (ETDEWEB)

    Eastaugh, Chris S.; Potzelsberger, Elisabeth; Hasenaueur, Hubert

    2011-03-15

    The purpose of this study is to determine if the climate change has had an apparent impact in Austrian forests. This research has been conducted on Norway spruce forests as this is the predominant species in Austria. Growth data between regions which have different temperature and precipitation trendsw was then compared, with results showing increased productivity in all regions thus implying that growth of the forest is driven by other factors than climate. This conclusion is consistent with previous studies supporting that forest growth is mainly driven by increasing nitrogen deposition.

  14. The apical actin fringe contributes to localized cell wall deposition and polarized growth in the lily pollen tube.

    Science.gov (United States)

    Rounds, Caleb M; Hepler, Peter K; Winship, Lawrence J

    2014-09-01

    In lily (Lilium formosanum) pollen tubes, pectin, a major component of the cell wall, is delivered through regulated exocytosis. The targeted transport and secretion of the pectin-containing vesicles may be controlled by the cortical actin fringe at the pollen tube apex. Here, we address the role of the actin fringe using three different inhibitors of growth: brefeldin A, latrunculin B, and potassium cyanide. Brefeldin A blocks membrane trafficking and inhibits exocytosis in pollen tubes; it also leads to the degradation of the actin fringe and the formation of an aggregate of filamentous actin at the base of the clear zone. Latrunculin B, which depolymerizes filamentous actin, markedly slows growth but allows focused pectin deposition to continue. Of note, the locus of deposition shifts frequently and correlates with changes in the direction of growth. Finally, potassium cyanide, an electron transport chain inhibitor, briefly stops growth while causing the actin fringe to completely disappear. Pectin deposition continues but lacks focus, instead being delivered in a wide arc across the pollen tube tip. These data support a model in which the actin fringe contributes to the focused secretion of pectin to the apical cell wall and, thus, to the polarized growth of the pollen tube. © 2014 American Society of Plant Biologists. All Rights Reserved.

  15. Electron molecular beam epitaxy: Layer-by-layer growth of complex oxides via pulsed electron-beam deposition

    International Nuclear Information System (INIS)

    Comes, Ryan; Liu Hongxue; Lu Jiwei; Gu, Man; Khokhlov, Mikhail; Wolf, Stuart A.

    2013-01-01

    Complex oxide epitaxial film growth is a rich and exciting field, owing to the wide variety of physical properties present in oxides. These properties include ferroelectricity, ferromagnetism, spin-polarization, and a variety of other correlated phenomena. Traditionally, high quality epitaxial oxide films have been grown via oxide molecular beam epitaxy or pulsed laser deposition. Here, we present the growth of high quality epitaxial films using an alternative approach, the pulsed electron-beam deposition technique. We demonstrate all three epitaxial growth modes in different oxide systems: Frank-van der Merwe (layer-by-layer); Stranski-Krastanov (layer-then-island); and Volmer-Weber (island). Analysis of film quality and morphology is presented and techniques to optimize the morphology of films are discussed.

  16. Metallorganic chemical vapor deposition and atomic layer deposition approaches for the growth of hafnium-based thin films from dialkylamide precursors for advanced CMOS gate stack applications

    Science.gov (United States)

    Consiglio, Steven P.

    To continue the rapid progress of the semiconductor industry as described by Moore's Law, the feasibility of new material systems for front end of the line (FEOL) process technologies needs to be investigated, since the currently employed polysilicon/SiO2-based transistor system is reaching its fundamental scaling limits. Revolutionary breakthroughs in complementary-metal-oxide-semiconductor (CMOS) technology were recently announced by Intel Corporation and International Business Machines Corporation (IBM), with both organizations revealing significant progress in the implementation of hafnium-based high-k dielectrics along with metal gates. This announcement was heralded by Gordon Moore as "...the biggest change in transistor technology since the introduction of polysilicon gate MOS transistors in the late 1960s." Accordingly, the study described herein focuses on the growth of Hf-based dielectrics and Hf-based metal gates using chemical vapor-based deposition methods, specifically metallorganic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD). A family of Hf source complexes that has received much attention recently due to their desirable properties for implementation in wafer scale manufacturing is the Hf dialkylamide precursors. These precursors are room temperature liquids and possess sufficient volatility and desirable decomposition characteristics for both MOCVD and ALD processing. Another benefit of using these sources is the existence of chemically compatible Si dialkylamide sources as co-precursors for use in Hf silicate growth. The first part of this study investigates properties of MOCVD-deposited HfO2 and HfSixOy using dimethylamido Hf and Si precursor sources using a customized MOCVD reactor. The second part of this study involves a study of wet and dry surface pre-treatments for ALD growth of HfO2 using tetrakis(ethylmethylamido)hafnium in a wafer scale manufacturing environment. The third part of this study is an investigation of

  17. Laboratory studies on the uptake of aromatic hydrocarbons by ice crystals during vapor depositional crystal growth

    Science.gov (United States)

    Fries, Elke; Starokozhev, Elena; Haunold, Werner; Jaeschke, Wolfgang; Mitra, Subir K.; Borrmann, Stephan; Schmidt, Martin U.

    Uptake of aromatic hydrocarbons (AH) by ice crystals during vapor deposit growth was investigated in a walk-in cold chamber at temperatures of 242, 251, and 260 K, respectively. Ice crystals were grown from ambient air in the presence of gaseous AH namely: benzene (C 6H 6), toluene (methylbenzene, C 7H 8), the C 8H 10 isomers ethylbenzene, o-, m-, p-xylene (dimethylbenzenes), the C 9H 12 isomers n-propylbenzene, 4-ethyltoluene, 1,3,5-trimethylbenzene (1,3,5-TMB), 1,2,4-trimethylbenzene (1,2,4-TMB), 1,2,3-trimethylbenzene (1,2,3-TMB), and the C 10H 14 compound tert.-butylbenzene. Gas-phase concentrations calculated at 295 K were 10.3-20.8 μg m -3. Uptake of AH was detected by analyzing vapor deposited ice with a very sensitive method composed of solid-phase micro-extraction (SPME), followed by gas chromatography/mass spectrometry (GC/MS). Ice crystal size was lower than 1 cm. At water vapor extents of 5.8, 6.0 and 8.1 g m -3, ice crystal shape changed with decreasing temperatures from a column at a temperature of 260 K, to a plate at 251 K, and to a dendrite at 242 K. Experimentally observed ice growth rates were between 3.3 and 13.3×10 -3 g s -1 m -2 and decreased at lower temperatures and lower value of water vapor concentration. Predicted growth rates were mostly slightly higher. Benzene, toluene, ethylbenzene, and xylenes (BTEX) were not detected in ice above their detection limits (DLs) of 25 pg g ice-1 (toluene, ethylbenzene, xylenes) and 125 pg g ice-1 (benzene) over the entire temperature range. Median concentrations of n-propylbenzene, 4-ethyltoluene, 1,3,5-TMB, tert.-butylbenzene, 1,2,4-TMB, and 1,2,3-TMB were between 4 and 176 pg g ice-1 at gas concentrations of 10.3-10.7 μg m -3 calculated at 295 K. Uptake coefficients ( K) defined as the product of concentration of AH in ice and density of ice related to the product of their concentration in the gas phase and ice mass varied between 0.40 and 10.23. K increased with decreasing temperatures. Values of

  18. 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.)

  19. Petri Nets

    Indian Academy of Sciences (India)

    GENERAL I ARTICLE ... In Part 1 of this two-part article, we have seen im- ..... mable logic controller and VLSI arrays, office automation systems, workflow management systems, ... complex discrete event and real-time systems; and Petri nets.

  20. 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 .

  1. Spatial Distributions of Potassium, Solutes, and Their Deposition Rates in the Growth Zone of the Primary Corn Root 1

    Science.gov (United States)

    Silk, Wendy Kuhn; Hsiao, Theodore C.; Diedenhofen, Ulrike; Matson, Christina

    1986-01-01

    Densities of osmoticum and potassium were measured as a function of distance from the tip of the primary root of Zea mays L. (cv WF9 × mo17). Millimeter segments were excised and analyzed for osmotic potential by a miniaturized freezing point depression technique, and for potassium by flame spectrophotometry. Local deposition rates were estimated from the continuity equation with values for density and growth velocity. Osmotic potential was uniform, −0.73 ± 0.05 megapascals, throughout the growth zone of well-watered roots. Osmoticum deposition rate was 260 μosmoles per gram fresh weight per hour. Potassium density fell from 117 micromoles per gram in the first mm region to 48 micromoles per gram at the base of the growth zone. Potassium deposition rates had a maximum of 29 micromoles per gram per hour at 3.5 millimeters from the tip and were positive (i.e. potassium was being added to the tissue) until 8 millimeters from the tip. The results are discussed in terms of ion relations of the growing zone and growth physics. PMID:16665121

  2. Heteroepitaxial Growth of Germanium-on-Silicon Using Ultrahigh-Vacuum Chemical Vapor Deposition with RF Plasma Enhancement

    Science.gov (United States)

    Alharthi, Bader; Grant, Joshua M.; Dou, Wei; Grant, Perry C.; Mosleh, Aboozar; Du, Wei; Mortazavi, Mansour; Li, Baohua; Naseem, Hameed; Yu, Shui-Qing

    2018-05-01

    Germanium (Ge) films have been grown on silicon (Si) substrate by ultrahigh-vacuum chemical vapor deposition with plasma enhancement (PE). Argon plasma was generated using high-power radiofrequency (50 W) to assist in germane decomposition at low temperature. The growth temperature was varied in the low range of 250°C to 450°C to make this growth process compatible with complementary metal-oxide-semiconductor technology. The material and optical properties of the grown Ge films were investigated. The material quality was determined by Raman and x-ray diffraction techniques, revealing growth of crystalline films in the temperature range of 350°C to 450°C. Photoluminescence spectra revealed improved optical quality at growth temperatures of 400°C and 450°C. Furthermore, material quality study using transmission electron microscopy revealed existence of defects in the Ge layer grown at 400°C. Based on the etch pit density, the average threading dislocation density in the Ge layer obtained at this growth temperature was measured to be 4.5 × 108 cm-2. This result was achieved without any material improvement steps such as use of graded buffer or thermal annealing. Comparison between PE and non-plasma-enhanced growth, in the same machine at otherwise the same growth conditions, indicated increased growth rate and improved material and optical qualities for PE growth.

  3. 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

  4. Thermal tolerance, net CO2 exchange and growth of a tropical tree species, Ficus insipida, cultivated at elevated daytime and nighttime temperatures.

    Science.gov (United States)

    Krause, G Heinrich; Cheesman, Alexander W; Winter, Klaus; Krause, Barbara; Virgo, Aurelio

    2013-06-15

    Global warming and associated increases in the frequency and amplitude of extreme weather events, such as heat waves, may adversely affect tropical rainforest plants via significantly increased tissue temperatures. In this study, the response to two temperature regimes was assessed in seedlings of the neotropical pioneer tree species, Ficus insipida. Plants were cultivated in growth chambers at strongly elevated daytime temperature (39°C), combined with either close to natural (22°C) or elevated (32°C) nighttime temperatures. Under both growth regimes, the critical temperature for irreversible leaf damage, determined by changes in chlorophyll a fluorescence, was approximately 51°C. This is comparable to values found in F. insipida growing under natural ambient conditions and indicates a limited potential for heat tolerance acclimation of this tropical forest tree species. Yet, under high nighttime temperature, growth was strongly enhanced, accompanied by increased rates of net photosynthetic CO2 uptake and diminished temperature dependence of leaf-level dark respiration, consistent with thermal acclimation of these key physiological parameters. Copyright © 2013 Elsevier GmbH. All rights reserved.

  5. Phytoplankton growth balanced by clam and zooplankton grazing and net transport into the low-salinity zone of the San Francisco Estuary

    Science.gov (United States)

    Kimmerer, Wim J.; Thompson, Janet K.

    2014-01-01

    We estimated the influence of planktonic and benthic grazing on phytoplankton in the strongly tidal, river-dominated northern San Francisco Estuary using data from an intensive study of the low salinity foodweb in 2006–2008 supplemented with long-term monitoring data. A drop in chlorophyll concentration in 1987 had previously been linked to grazing by the introduced clam Potamocorbula amurensis, but numerous changes in the estuary may be linked to the continued low chlorophyll. We asked whether phytoplankton continued to be suppressed by grazing and what proportion of the grazing was by benthic bivalves. A mass balance of phytoplankton biomass included estimates of primary production and grazing by microzooplankton, mesozooplankton, and clams. Grazing persistently exceeded net phytoplankton growth especially for larger cells, and grazing by microzooplankton often exceeded that by clams. A subsidy of phytoplankton from other regions roughly balanced the excess of grazing over growth. Thus, the influence of bivalve grazing on phytoplankton biomass can be understood only in the context of limits on phytoplankton growth, total grazing, and transport.

  6. Effective role of deposition duration on the growth of V{sub 2}O{sub 5} nanostructured thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Rabindar Kumar, E-mail: rkrksharma6@gmail.com; Saini, Sujit Kumar; Singh, Megha; Reddy, G. B. [Thin film laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi – 110016 (India)

    2016-05-23

    In this report, vanadium pentoxide nanostructured thin films (NSTs) with nanoplates (NPs) have synthesized on Ni coated glass substrate employing plasma assisted sublimation process (PASP), as a function of deposition/growth durations. The effect of deposition durations on the morphological, structural, vibrational, and compositional properties have been investigated one by one. The structural and vibrational studies endorsed that the grown NPs have only orthorhombic phase, no other sub oxide phases are recorded in the limit of resolution. The morphological results of all samples using SEM, revealed that the features, coverage density, and alignments of NPs are greatly controlled by deposition duration and the best sample is obtained for 25 min (S2). Further, the more insight information is accomplished by HRTEM/SAED on the best featured sample, which confirmed the single crystalline nature of NPs. The XPS result again confirmed the compositional purity and the nearly stoichiometric nature of NPs.

  7. Nucleation/Growth Mechanisms and Morphological Evolution of Porous MnO2 Coating Deposited on Graphite for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Wenxin Huang

    2017-10-01

    Full Text Available The nucleation and growth mechanisms of porous MnO2 coating deposited on graphite in MnSO4 solution were investigated in detail by cyclic voltammetry, chronoamperometry and scanning electron microscopy. The electrochemical properties of honeycomb-like MnO2 were evaluated by cycle voltammetry and galvanostatic charge-discharge. Results indicated that MnO2 was synthesized by the following steps: Mn2+→ Mn3++ e-, Mn3++2H2O → MnOOH + 3H+, and MnOOH → MnO2 + H++ e-. The deposition of MnO2 was divided into four stages. A short incubation period (approximately 1.5 s was observed, prior to nucleation. The decreasing trend of the current slowed as time increased due to nucleation and MnO2 growth in the second stage. A huge number of nuclei were formed by instantaneous nucleation, and these nuclei grew and connected with one another at an exceedingly short time (0.5 s. In the third stage, the gaps in-between initial graphite flakes were filled with MnO2 until the morphology of the flakes gradually became similar to that of the MnO2-deposited layer. In the fourth stage, the graphite electrode was covered completely with a thick and dense layer of MnO2 deposits. All MnO2 electrodes at different deposition times obtained nearly the same specific capacitance of approximately 186 F/g, thus indicating that the specific capacitance of the electrodes is not related with deposition time.

  8. Does chronic nitrogen deposition during biomass growth affect atmospheric emissions from biomass burning?

    Science.gov (United States)

    Michael R Giordano; Joey Chong; David R Weise; Akua A Asa-Awuku

    2016-01-01

    Chronic nitrogen deposition has measureable impacts on soil and plant health.We investigate burning emissions from biomass grown in areas of high and low NOx deposition. Gas and aerosolphase emissions were measured as a function of photochemical aging in an environmental chamber at UC-Riverside. Though aerosol chemical speciation was not...

  9. Growth characteristics of inclined columns produced by Glancing Angle Deposition (GLAD) and colloidal lithography

    DEFF Research Database (Denmark)

    Foss, Morten; Besenbacher, Flemming; Sutherland, Duncan S

    2011-01-01

    Nanocolumns were produced by performing Glancing Angle Deposition (GLAD) onto self-assembled template arrays consisting of platinum coated polystyrene spheres. By varying the angle of incidence (θ = 35°, 10° and 5°) and the deposited surface mass density it was possible to control the shape of th...

  10. 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.

  11. 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.

  12. Water availability drives gas exchange and growth of trees in northeastern US, not elevated CO2 and reduced acid deposition.

    Science.gov (United States)

    Levesque, Mathieu; Andreu-Hayles, Laia; Pederson, Neil

    2017-04-10

    Dynamic global vegetation models (DGVM) exhibit high uncertainty about how climate change, elevated atmospheric CO 2 (atm. CO 2 ) concentration, and atmospheric pollutants will impact carbon sequestration in forested ecosystems. Although the individual roles of these environmental factors on tree growth are understood, analyses examining their simultaneous effects are lacking. We used tree-ring isotopic data and structural equation modeling to examine the concurrent and interacting effects of water availability, atm. CO 2 concentration, and SO 4 and nitrogen deposition on two broadleaf tree species in a temperate mesic forest in the northeastern US. Water availability was the strongest driver of gas exchange and tree growth. Wetter conditions since the 1980s have enhanced stomatal conductance, photosynthetic assimilation rates and, to a lesser extent, tree radial growth. Increased water availability seemingly overrides responses to reduced acid deposition, CO 2 fertilization, and nitrogen deposition. Our results indicate that water availability as a driver of ecosystem productivity in mesic temperate forests is not adequately represented in DGVMs, while CO 2 fertilization is likely overrepresented. This study emphasizes the importance to simultaneously consider interacting climatic and biogeochemical drivers when assessing forest responses to global environmental changes.

  13. RESTful NET

    CERN Document Server

    Flanders, Jon

    2008-01-01

    RESTful .NET is the first book that teaches Windows developers to build RESTful web services using the latest Microsoft tools. Written by Windows Communication Foundation (WFC) expert Jon Flanders, this hands-on tutorial demonstrates how you can use WCF and other components of the .NET 3.5 Framework to build, deploy and use REST-based web services in a variety of application scenarios. RESTful architecture offers a simpler approach to building web services than SOAP, SOA, and the cumbersome WS- stack. And WCF has proven to be a flexible technology for building distributed systems not necessa

  14. Improved netting

    International Nuclear Information System (INIS)

    Bramley, A.; Clabburn, R.J.T.

    1976-01-01

    A method is described for producing netting composed of longitudinal and transverse threads of irradiation cross linked thermoplastic material, the threads being joined together at their crossings by moulded masses of cross linked thermoplastic material. The thread may be formed of polyethylene filaments, subjected to a radiation dose of 15 to 25 MR. The moulding can be conducted at 245 0 to 260 0 C or higher. The product is claimed to be an improved quality of netting, with bonds of increased strength between crossing threads. (U.K.)

  15. [Effects of simulated nitrogen deposition on weeds growth and nitrogen uptake].

    Science.gov (United States)

    Jiang, Qiqing; Tang, Jianjun; Chen, Xin; Chen, Jing; Yang, Ruyi; Hu, S

    2005-05-01

    In this paper, a greenhouse experiment was conducted to study the responses of different functional groups weeds to simulated nitrogen deposition (4.0 g N.m(-2).yr(-1)). Native weed species Poa annua, Lolium perenne, Avena fatua, Medicago lupulina, Trifolium repens, Plantago virginica, Veronica didyma, Echinochloa crusgalli var. mitis, Eleusine indica and Amaranthus spinosus in orchard ecosystem were used test materials, and their above-and underground biomass and nitrogen uptake were measured. The results showed that under simulated N deposition, the total biomass, shoot biomass and root biomass of all weed species tended increase, while the total biomass was differed for different functional groups of weeds. The biomass of C4 grass, legumes and C3 grass was significantly increased under N deposition, while that of C3 and C4 forbs was not significantly impacted. The root/shoot biomass ratio of Avena fatua and Plantago virginica was enhanced by N deposition, but that of Poa annu, Lolium perenne, Medicago lupulina, Trifolium repens and Amarathus spinosus was not impacted significantly. N deposition had no significant effect on plant N concentration, but significantly enhanced the N uptake of all test weed species except Amarathus spinosus, Poa annua and Veronica didyma. was suggested that the further increase of N deposition might speed up the changes of the community structure weed species due to their different responses to N deposition.

  16. Petri Nets

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 9. Petri Nets - Applications. Y Narahari. General Article Volume 4 Issue 9 September 1999 pp 44-52 ... Author Affiliations. Y Narahari1. Department of Computer Science and Automation, Indian Institute of Science, Bangalore 560 012, India.

  17. Net Gain

    International Development Research Centre (IDRC) Digital Library (Canada)

    Describing the effect of tax incentives for import, production, and sale of nets and insecticides; and ..... So far, China is the only country where a system for the routine treatment of ...... 1993), and the trials in Ecuador and Peru (Kroeger et al.

  18. Selective epitaxial growth of Ge1-xSnx on Si by using metal-organic chemical vapor deposition

    Science.gov (United States)

    Washizu, Tomoya; Ike, Shinichi; Inuzuka, Yuki; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

    2017-06-01

    Selective epitaxial growth of Ge and Ge1-xSnx layers on Si substrates was performed by using metal-organic chemical vapor deposition (MOCVD) with precursors of tertiary-butyl-germane (t-BGe) and tri-butyl-vinyl-tin (TBVSn). We investigated the effects of growth temperature and total pressure during growth on the selectivity and the crystallinity of the Ge and Ge1-xSnx epitaxial layers. Under low total pressure growth conditions, the dominant mechanism of the selective growth of Ge epitaxial layers is the desorption of the Ge precursors. At a high total pressure case, it is needed to control the surface migration of precursors to realize the selectivity because the desorption of Ge precursors was suppressed. The selectivity of Ge growth was improved by diffusion of the Ge precursors on the SiO2 surfaces when patterned substrates were used at a high total pressure. The selective epitaxial growth of Ge1-xSnx layer was also realized using MOCVD. We found that the Sn precursors less likely to desorb from the SiO2 surfaces than the Ge precursors.

  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. Growth of Self-Catalyzed InP Nanowires by Metalorganic Chemical Vapour Deposition

    International Nuclear Information System (INIS)

    Lv Xiao-Long; Zhang Xia; Yan Xin; Liu Xiao-Long; Cui Jian-Gong; Li Jun-Shuai; Huang Yong-Qing; Ren Xiao-Min

    2012-01-01

    The fabrication of self-catalyzed InP nanowires (NWs) is investigated under different growth conditions. Indium droplets induced by surface reconstruction act as nucleation sites for NW growth. Vertical standing NWs with uniform cross sections are obtained under optimized conditions. It is confirmed that the growth rate of NWs is strongly affected by the surface diffusion adatoms while contributions from the direct impingement of vapor species onto the In droplets can be negligible. The results indicate that the droplet acts as an adatom collector rather than a catalyst. Moreover, the diffusion flow rate of adatoms increases with time at the beginning of growth and stabilizes as the growth proceeds

  1. High quality superconducting titanium nitride thin film growth using infrared pulsed laser deposition

    Science.gov (United States)

    Torgovkin, A.; Chaudhuri, S.; Ruhtinas, A.; Lahtinen, M.; Sajavaara, T.; Maasilta, I. J.

    2018-05-01

    Superconducting titanium nitride (TiN) thin films were deposited on magnesium oxide, sapphire and silicon nitride substrates at 700 °C, using a pulsed laser deposition (PLD) technique, where infrared (1064 nm) pulses from a solid-state laser were used for the ablation from a titanium target in a nitrogen atmosphere. Structural studies performed with x-ray diffraction showed the best epitaxial crystallinity for films deposited on MgO. In the best films, superconducting transition temperatures, T C, as high as 4.8 K were observed, higher than in most previous superconducting TiN thin films deposited with reactive sputtering. A room temperature resistivity down to ∼17 μΩ cm and residual resistivity ratio up to 3 were observed in the best films, approaching reported single crystal film values, demonstrating that PLD is a good alternative to reactive sputtering for superconducting TiN film deposition. For less than ideal samples, the suppression of the film properties were correlated mostly with the unintended incorporation of oxygen (5–10 at%) in the film, and for high oxygen content films, vacuum annealing was also shown to increase the T C. On the other hand, superconducting properties were surprisingly insensitive to the nitrogen content, with high quality films achieved even in the highly nitrogen rich, Ti:N = 40/60 limit. Measures to limit oxygen exposure during deposition must be taken to guarantee the best superconducting film properties, a fact that needs to be taken into account with other deposition methods, as well.

  2. Growth, structure and stability of sputter-deposited MoS2 thin films

    Directory of Open Access Journals (Sweden)

    Reinhard Kaindl

    2017-05-01

    Full Text Available Molybdenum disulphide (MoS2 thin films have received increasing interest as device-active layers in low-dimensional electronics and also as novel catalysts in electrochemical processes such as the hydrogen evolution reaction (HER in electrochemical water splitting. For both types of applications, industrially scalable fabrication methods with good control over the MoS2 film properties are crucial. Here, we investigate scalable physical vapour deposition (PVD of MoS2 films by magnetron sputtering. MoS2 films with thicknesses from ≈10 to ≈1000 nm were deposited on SiO2/Si and reticulated vitreous carbon (RVC substrates. Samples deposited at room temperature (RT and at 400 °C were compared. The deposited MoS2 was characterized by macro- and microscopic X-ray, electron beam and light scattering, scanning and spectroscopic methods as well as electrical device characterization. We find that room-temperature-deposited MoS2 films are amorphous, of smooth surface morphology and easily degraded upon moderate laser-induced annealing in ambient conditions. In contrast, films deposited at 400 °C are nano-crystalline, show a nano-grained surface morphology and are comparatively stable against laser-induced degradation. Interestingly, results from electrical transport measurements indicate an unexpected metallic-like conduction character of the studied PVD MoS2 films, independent of deposition temperature. Possible reasons for these unusual electrical properties of our PVD MoS2 thin films are discussed. A potential application for such conductive nanostructured MoS2 films could be as catalytically active electrodes in (photo-electrocatalysis and initial electrochemical measurements suggest directions for future work on our PVD MoS2 films.

  3. In-situ epitaxial growth of heavily phosphorus doped SiGe by low pressure chemical vapor deposition

    CERN Document Server

    Lee, C J

    1998-01-01

    We have studied epitaxial crystal growth of Si sub 1 sub - sub x Ge sub x films on silicon substrates at 550 .deg. C by low pressure chemical vapor deposition. In a low PH sub 3 partial pressure region such as below 1.25x10 sup - sup 3 Pa, both the phosphorus and carrier concentrations increased with increasing PH sub 3 partial pressure, but the deposition rate and the Ge fraction remained constant. In a higher PH sub 3 partial pressure region, the deposition rate, the phosphorus concentration, and the carrier concentration decreased, while the Ge fraction increased. These suggest that high surface coverage of phosphorus suppresses both SiH sub 4 and GeH sub 4 adsorption/reactions on the surfaces, and its suppression effect on SiH sub 4 is actually much stronger than on GeH sub 4. In particular, epitaxial crystal growth is largely controlled by surface coverage effect of phosphorus in a higher PH sub 3 partial pressure region.

  4. Thickness dependent growth of low temperature atomic layer deposited zinc oxide films

    International Nuclear Information System (INIS)

    Montiel-González, Z.; Castelo-González, O.A.; Aguilar-Gama, M.T.; Ramírez-Morales, E.; Hu, H.

    2017-01-01

    Highlights: • Polycrystalline columnar ZnO thin films deposited by ALD at low temperatures. • Higher deposition temperature leads to a greater surface roughness in the ALD ZnO films. • Higher temperature originates larger refractive index values of the ALD ZnO films. • ZnO thin films were denser as the numbers of ALD deposition cycles were larger. • XPS analysis revels mayor extent of the DEZ reaction during the ALD process. - Abstract: Zinc oxide films are promising to improve the performance of electronic devices, including those based on organic materials. However, the dependence of the ZnO properties on the preparation conditions represents a challenge to obtain homogeneous thin films that satisfy specific applications. Here, we prepared ZnO films of a wide range of thicknesses by atomic layer deposition (ALD) at relatively low temperatures, 150 and 175 °C. From the results of X-ray photoelectron spectroscopy, X-ray diffraction and Spectroscopic Ellipsometry it is concluded that the polycrystalline structure of the wurtzite is the main phase of the ALD samples, with OH groups on their surface. Ellipsometry revealed that the temperature and the deposition cycles have a strong effect on the films roughness. Scanning electron micrographs evidenced such effect, through the large pyramids developed at the surface of the films. It is concluded that crystalline ZnO thin films within a broad range of thickness and roughness can be obtained for optic or optoelectronic applications.

  5. Growth and Properties of Cl- Incorporated ZnO Nanofilms Grown by Ultrasonic Spray-Assisted Chemical Vapor Deposition.

    Science.gov (United States)

    Chen, Tingfang; Wang, Aiji; Kong, Lingrui; Li, Yongliang; Wang, Yinshu

    2016-04-01

    Pure and Cl- incorporated ZnO nanofilms were grown by the ultrasonic spray-assisted chemical vapor deposition (CVD) method. The properties of the nanofilms were investigated. The effects of growth temperature and Cl- concentration on the crystal structure, morphology, and optical properties of the nanofilms were studied. Temperature plays an important role in the growth mode and morphology of the pure nanofilms. Preferential growth along the c-axis occurs only at modulating temperature. Lower temperature suppresses the preferential growth, and higher temperature suppresses the growth of the nanofilms. The morphologies of the nanofilms change from lamellar and spherical structures into hexagonal platelets, then into separated nanoparticles with an increase in the temperature. Incorporating Cl- results in the lattice contracting gradually along with c-axis. Grains composing the nanofilms refine, and the optical gap broadens with increasing of Cl- concentration in growth precursor. Incorporating Cl- could reduce oxygen vacancies and passivate the non-irradiated centers, thus enhancing the UV emission and suppressing the visible emission of ZnO nanofilms.

  6. 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.

  7. Growth and properties of the CuInS2 thin films produced by glancing angle deposition

    International Nuclear Information System (INIS)

    Akkari, F. Chaffar; Kanzari, M.; Rezig, B.

    2008-01-01

    We use the glancing angle deposition technique (GLAD) to grow CuInS 2 thin films by a vacuum thermal method onto glass substrates. During deposition, the substrate temperature was maintained at 200 deg. C. Due to shadowing effect the oblique angle deposition technique can produce nanorods tilted toward the incident deposition flux. The evaporated atoms arrive at the growing interface at a fixed angle θ measured from the substrate normal. The substrate is rotated with rotational speed ω fixed at 0.033 rev s -1 . We show that the use of this growth technique leads to an improvement in the optical properties of the films. Indeed high absorption coefficients (10 5 -3.10 5 cm -1 ) in the visible range and near-IR spectral range are reached. In the case of the absence of the substrate rotation, scanning electron microscopy pictures show that the structure of the resulting film consists of nanocolumns that are progressively inclined towards the evaporation source as the incident angle was increased. If a rapid azimuthal rotation accompanies the substrate tilt, the resulting nanostructure is composed of an array of pillars normal to the substrate. The surface morphology show an improvement without presence of secondary phases for higher incident angles (θ > 60 deg.)

  8. Net Locality

    DEFF Research Database (Denmark)

    de Souza e Silva, Adriana Araujo; Gordon, Eric

    Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps......, to location-based social networks and games, such as Foursquare and facebook. Warns of the threats these technologies, such as data surveillance, present to our sense of privacy, while also outlining the opportunities for pro-social developments. Provides a theory of the web in the context of the history...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....

  9. Growth of strained, ferroelectric NaNbO{sub 3} thin films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sellmann, Jan; Schwarzkopf, Jutta; Duk, Andreas; Kwasniewski, Albert; Schmidbauer, Martin; Fornari, Roberto [IKZ, Berlin (Germany)

    2012-07-01

    Due to its promising ferro-/piezoelectric properties and high Curie temperature NaNbO{sub 3} has attracted much attention. In contrast to bulk crystals, thin epitaxial films may incorporate and maintain a certain compressive or tensile lattice strain, depending on the used substrate/film combination. This deformation of the crystal lattice is known to strongly influence the ferroelectric properties of perovskites. In the case of NaNbO{sub 3} compressive strain is achieved in films deposited on NdGaO{sub 3} and SrTiO{sub 3} substrates while deposition on DyScO{sub 3} and TbScO{sub 3} leads to tensile in-plane strain. In order to characterize and practically apply the ferroelectric films, it is necessary to embed them in a capacitor structure for which we use pseudomorphically grown SrRuO{sub 3} as bottom electrodes. We report on the deposition of SrRuO{sub 3} and NaNbO{sub 3} single layers on SrTiO{sub 3}, DyScO{sub 3}, TbScO{sub 3} and NbGaO{sub 3} substrates by means of pulsed laser deposition. By adjusting the substrate temperature, the oxygen partial pressure and the laser frequency we have successfully deposited smooth, strained, single phase NaNbO{sub 3} thin films. Investigations of the films by atomic force microscopy and high resolution X-ray diffraction reveal the dependence of the surface morphology and the incorporated lattice strain on the deposition parameters and the lattice mismatch, respectively. All films exhibit piezoelectric properties, as proven by piezoresponse force microscopy.

  10. Consistent treatment of ground deposition together with species growth and decay during atmospheric transport

    International Nuclear Information System (INIS)

    Murphy, B.D.; Nelson, C.B.; Ohr, S.Y.

    1981-01-01

    We discuss the adaptation of a trajectory model to an initial pollutant species and a series of successor species at mesoscale distances. The effect of source height is discussed since it is important in determining close-in ground level concentration, which influences plume depletion due to dry deposition. A scheme is outlined which handles deposition and species decay in a consistent manner and which does so for an arbitrary number of successor pollutant species. This scheme is discussed in terms of a Lagrangian trajectory model which accounts for initial source height and which calculates ground-level concentrations out to mesoscale distances

  11. CN distribution in flame deposition of diamond and its relation to the growth rate, morphology, and nitrogen incorporation of the diamond layer

    NARCIS (Netherlands)

    Klein-Douwel, R.J.H.; Schermer, J.J.; Meulen, ter J.J.

    1998-01-01

    Two-dimensional laser-induced fluorescence (2D-LIF) measurements areapplied to the chemical vapour deposition (CVD) of diamond by anoxyacetylene flame to visualize the distribution of CN in the gas phaseduring the diamond growth process. The obtained diamond deposits arecharacterized by optical as

  12. Towards engineered branch placement: Unreal™ match between vapour-liquid-solid glancing angle deposition nanowire growth and simulation

    International Nuclear Information System (INIS)

    Taschuk, M. T.; Tucker, R. T.; LaForge, J. M.; Beaudry, A. L.; Kupsta, M. R.; Brett, M. J.

    2013-01-01

    The vapour-liquid-solid glancing angle deposition (VLS-GLAD) process is capable of producing complex nanotree structures with control over azimuthal branch orientation and height. We have developed a thin film growth simulation including ballistic deposition, simplified surface diffusion, and droplet-mediated cubic crystal growth for the VLS-GLAD process using the Unreal TM Development Kit. The use of a commercial game engine has provided an interactive environment while allowing a custom physics implementation. Our simulation's output is verified against experimental data, including a volumetric film reconstruction produced using focused ion beam and scanning-electron microscopy (SEM), crystallographic texture, and morphological characteristics such as branch orientation. We achieve excellent morphological and texture agreement with experimental data, as well as qualitative agreement with SEM imagery. The simplified physics in our model reproduces the experimental films, indicating that the dominant role flux geometry plays in the VLS-GLAD competitive growth process responsible for azimuthally oriented branches and biaxial crystal texture evolution. The simulation's successful reproduction of experimental data indicates that it should have predictive power in designing novel VLS-GLAD structures

  13. Towards engineered branch placement: Unreal™ match between vapour-liquid-solid glancing angle deposition nanowire growth and simulation

    Science.gov (United States)

    Taschuk, M. T.; Tucker, R. T.; LaForge, J. M.; Beaudry, A. L.; Kupsta, M. R.; Brett, M. J.

    2013-12-01

    The vapour-liquid-solid glancing angle deposition (VLS-GLAD) process is capable of producing complex nanotree structures with control over azimuthal branch orientation and height. We have developed a thin film growth simulation including ballistic deposition, simplified surface diffusion, and droplet-mediated cubic crystal growth for the VLS-GLAD process using the UnrealTM Development Kit. The use of a commercial game engine has provided an interactive environment while allowing a custom physics implementation. Our simulation's output is verified against experimental data, including a volumetric film reconstruction produced using focused ion beam and scanning-electron microscopy (SEM), crystallographic texture, and morphological characteristics such as branch orientation. We achieve excellent morphological and texture agreement with experimental data, as well as qualitative agreement with SEM imagery. The simplified physics in our model reproduces the experimental films, indicating that the dominant role flux geometry plays in the VLS-GLAD competitive growth process responsible for azimuthally oriented branches and biaxial crystal texture evolution. The simulation's successful reproduction of experimental data indicates that it should have predictive power in designing novel VLS-GLAD structures.

  14. Simulation of nucleation and growth of atomic layer deposition phosphorus for doping of advanced FinFETs

    International Nuclear Information System (INIS)

    Seidel, Thomas E.; Goldberg, Alexander; Halls, Mat D.; Current, Michael I.

    2016-01-01

    Simulations for the nucleation and growth of phosphorus films were carried out using density functional theory. The surface was represented by a Si 9 H 12 truncated cluster surface model with 2 × 1-reconstructured (100) Si-OH terminations for the initial reaction sites. Chemistries included phosphorous halides (PF 3 , PCl 3 , and PBr 3 ) and disilane (Si 2 H 6 ). Atomic layer deposition (ALD) reaction sequences were illustrated with three-dimensional molecular models using sequential PF 3 and Si 2 H 6 reactions and featuring SiFH 3 as a byproduct. Exothermic reaction pathways were developed for both nucleation and growth for a Si-OH surface. Energetically favorable reactions for the deposition of four phosphorus atoms including lateral P–P bonding were simulated. This paper suggests energetically favorable thermodynamic reactions for the growth of elemental phosphorus on (100) silicon. Phosphorus layers made by ALD are an option for doping advanced fin field-effect transistors (FinFETs). Phosphorus may be thermally diffused into the silicon or recoil knocked in; simulations of the recoil profile of phosphorus into a FinFET surface are illustrated

  15. Impact of microcrystalline silicon carbide growth using hot-wire chemical vapor deposition on crystalline silicon surface passivation

    International Nuclear Information System (INIS)

    Pomaska, M.; Beyer, W.; Neumann, E.; Finger, F.; Ding, K.

    2015-01-01

    Highly crystalline microcrystalline silicon carbide (μc-SiC:H) with excellent optoelectronic material properties is a promising candidate as highly transparent doped layer in silicon heterojunction (SHJ) solar cells. These high quality materials are usually produced using hot wire chemical vapor deposition under aggressive growth conditions giving rise to the removal of the underlying passivation layer and thus the deterioration of the crystalline silicon (c-Si) surface passivation. In this work, we introduced the n-type μc-SiC:H/n-type μc-SiO x :H/intrinsic a-SiO x :H stack as a front layer configuration for p-type SHJ solar cells with the μc-SiO x :H layer acting as an etch-resistant layer against the reactive deposition conditions during the μc-SiC:H growth. We observed that the unfavorable expansion of micro-voids at the c-Si interface due to the in-diffusion of hydrogen atoms through the layer stack might be responsible for the deterioration of surface passivation. Excellent lifetime values were achieved under deposition conditions which are needed to grow high quality μc-SiC:H layers for SHJ solar cells. - Highlights: • High surface passivation quality was preserved after μc-SiC:H deposition. • μc-SiC:H/μc-SiO x :H/a-SiO x :H stack a promising front layer configuration • Void expansion at a-SiO x :H/c-Si interface for deteriorated surface passivation • μc-SiC:H provides a high transparency and electrical conductivity.

  16. Role of boundary layer diffusion in vapor deposition growth of chalcogenide nanosheets: the case of GeS.

    Science.gov (United States)

    Li, Chun; Huang, Liang; Snigdha, Gayatri Pongur; Yu, Yifei; Cao, Linyou

    2012-10-23

    We report a synthesis of single-crystalline two-dimensional GeS nanosheets using vapor deposition processes and show that the growth behavior of the nanosheet is substantially different from those of other nanomaterials and thin films grown by vapor depositions. The nanosheet growth is subject to strong influences of the diffusion of source materials through the boundary layer of gas flows. This boundary layer diffusion is found to be the rate-determining step of the growth under typical experimental conditions, evidenced by a substantial dependence of the nanosheet's size on diffusion fluxes. We also find that high-quality GeS nanosheets can grow only in the diffusion-limited regime, as the crystalline quality substantially deteriorates when the rate-determining step is changed away from the boundary layer diffusion. We establish a simple model to analyze the diffusion dynamics in experiments. Our analysis uncovers an intuitive correlation of diffusion flux with the partial pressure of source materials, the flow rate of carrier gas, and the total pressure in the synthetic setup. The observed significant role of boundary layer diffusions in the growth is unique for nanosheets. It may be correlated with the high growth rate of GeS nanosheets, ~3-5 μm/min, which is 1 order of magnitude higher than other nanomaterials (such as nanowires) and thin films. This fundamental understanding of the effect of boundary layer diffusions may generally apply to other chalcogenide nanosheets that can grow rapidly. It can provide useful guidance for the development of general paradigms to control the synthesis of nanosheets.

  17. Self-catalytic growth of tin oxide nanowires by chemical vapor deposition process

    CSIR Research Space (South Africa)

    Thabethe, BS

    2013-01-01

    Full Text Available The authors report on the synthesis of tin oxide (SnO(sub2)) nanowires by a chemical vapor deposition (CVD) process. Commercially bought SnO nanopowders were vaporized at 1050°C for 30 minutes with argon gas continuously passing through the system...

  18. In situ growth optimization in focused electron-beam induced deposition

    Directory of Open Access Journals (Sweden)

    Paul M. Weirich

    2013-12-01

    Full Text Available We present the application of an evolutionary genetic algorithm for the in situ optimization of nanostructures that are prepared by focused electron-beam-induced deposition (FEBID. It allows us to tune the properties of the deposits towards the highest conductivity by using the time gradient of the measured in situ rate of change of conductance as the fitness parameter for the algorithm. The effectiveness of the procedure is presented for the precursor W(CO6 as well as for post-treatment of Pt–C deposits, which were obtained by the dissociation of MeCpPt(Me3. For W(CO6-based structures an increase of conductivity by one order of magnitude can be achieved, whereas the effect for MeCpPt(Me3 is largely suppressed. The presented technique can be applied to all beam-induced deposition processes and has great potential for a further optimization or tuning of parameters for nanostructures that are prepared by FEBID or related techniques.

  19. Fabrication of Nanolaminates with Ultrathin Nanolayers Using Atomic Layer Deposition: Nucleation & Growth Issues

    Science.gov (United States)

    2009-02-01

    Tecnologia de Superficies y Materiales (SMCTSM), XXVII Congreso Nacional, Oaxaca, Oaxaca, Mexico, September 26, 2007. 26. "Atomic Layer Deposition of...Nanolaminates: Fabrication and Properties" (Plenary Lecture), Sociedad Mexicana de Ciencia y Tecnologia de Superficies y Materiales (SMCTSM), XXVII

  20. Influence of the catalyst type on the growth of carbon nanotubes via methane chemical vapor deposition

    NARCIS (Netherlands)

    Jodin, Lucie; Dupuis, Anne-Claire; Rouvière, Emmanuelle; Reiss, Peter

    2006-01-01

    The preparation of the catalyst is one of the key parameters which governs the quality of carbon nanotubes (CNTs) grown by catalyzed chemical vapor deposition (CVD). We investigated the influence of three different procedures of catalyst preparation on the type and diameter of CNTs formed under

  1. Low temperature growth of gallium oxide thin films via plasma enhanced atomic layer deposition

    NARCIS (Netherlands)

    O'Donoghue, R.; Rechmann, J.; Aghaee, M.; Rogalla, D.; Becker, H.-W.; Creatore, M.; Wieck, A.D.; Devi, A.P.K.

    2017-01-01

    Herein we describe an efficient low temperature (60–160 °C) plasma enhanced atomic layer deposition (PEALD) process for gallium oxide (Ga2O3) thin films using hexakis(dimethylamido)digallium [Ga(NMe2)3]2 with oxygen (O2) plasma on Si(100). The use of O2 plasma was found to have a significant

  2. Year 2020: Consequences of population growth and development on deposition of oxidized nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Galloway, J N [Environmental Sciences Dept., Univ. of Virginia, Charlottesville, VA (United States); Levy, H; Kasibhatla, P S [NOAA Geophysical Fluid Dynamics Lab., Princeton, NJ (United States)

    1994-01-01

    With a current world population of 5.3 billion, fossil fuel and biomass burning have already greatly increased the emission of fixed nitrogen to the global atmosphere. In 2020, with a projected population of 8.5 billion and an assumed 100% increase in per capita energy consumption relative to 1980 by the lesser developed countries, we predict an approximate 25% increase in total nitrogen deposition in the more developed country source regions such as North America. In addition, reactive nitrogen deposition will at least double in less developed regions, such as SE Asia and Latin America, and will increase by more than 50% over the oceans of the Northern Hemisphere. Although we also predict significant increases in the deposition of nitrogen from fossil-fuel sources over most of the Southern Hemisphere, particularly Africa, the tropical eastern Pacific, and the southern Atlantic and Indian Oceans, biomass burning and the natural sources of nitrogen oxides (lightning and biogenic soil emissions) are also important in these regions. This increased deposition has the potential to fertilize both terrestrial and marine ecosystems, resulting in the sequestering of carbon. Increases in nitrogen deposition have also been shown not only to acidify ecosystems but also to increase emissions of nitric oxide (NO), nitrous oxide (N[sub 2]O), carbonyl sulfide (COS), and carbon+sulfur (CS[sub 2]) to the atmosphere and decrease methane (CH[sub 4]) consumption in forest soils. We also find that the atmospheric levels of nitrogen oxides increase significantly throughout much of the Northern Hemisphere and populated regions of the Southern Hemisphere. This increase may lead to larger ozone concentrations with resulting increases in the oxidative capacity of the remote atmosphere and its ability to absorb IR radiation. 31 refs, 3 figs, 1 tab

  3. Year 2020: Consequences of population growth and development on deposition of oxidized nitrogen

    International Nuclear Information System (INIS)

    Galloway, J.N.; Levy, H.; Kasibhatla, P.S.

    1994-01-01

    With a current world population of 5.3 billion, fossil fuel and biomass burning have already greatly increased the emission of fixed nitrogen to the global atmosphere. In 2020, with a projected population of 8.5 billion and an assumed 100% increase in per capita energy consumption relative to 1980 by the lesser developed countries, we predict an approximate 25% increase in total nitrogen deposition in the more developed country source regions such as North America. In addition, reactive nitrogen deposition will at least double in less developed regions, such as SE Asia and Latin America, and will increase by more than 50% over the oceans of the Northern Hemisphere. Although we also predict significant increases in the deposition of nitrogen from fossil-fuel sources over most of the Southern Hemisphere, particularly Africa, the tropical eastern Pacific, and the southern Atlantic and Indian Oceans, biomass burning and the natural sources of nitrogen oxides (lightning and biogenic soil emissions) are also important in these regions. This increased deposition has the potential to fertilize both terrestrial and marine ecosystems, resulting in the sequestering of carbon. Increases in nitrogen deposition have also been shown not only to acidify ecosystems but also to increase emissions of nitric oxide (NO), nitrous oxide (N 2 O), carbonyl sulfide (COS), and carbon+sulfur (CS 2 ) to the atmosphere and decrease methane (CH 4 ) consumption in forest soils. We also find that the atmospheric levels of nitrogen oxides increase significantly throughout much of the Northern Hemisphere and populated regions of the Southern Hemisphere. This increase may lead to larger ozone concentrations with resulting increases in the oxidative capacity of the remote atmosphere and its ability to absorb IR radiation. 31 refs, 3 figs, 1 tab

  4. Real-time optical diagnostics of graphene growth induced by pulsed chemical vapor deposition

    Science.gov (United States)

    Puretzky, Alexander A.; Geohegan, David B.; Pannala, Sreekanth; Rouleau, Christopher M.; Regmi, Murari; Thonnard, Norbert; Eres, Gyula

    2013-06-01

    The kinetics and mechanisms of graphene growth on Ni films at 720-880 °C have been measured using fast pulses of acetylene and real-time optical diagnostics. In situ UV-Raman spectroscopy was used to unambiguously detect isothermal graphene growth at high temperatures, measure the growth kinetics with ~1 s temporal resolution, and estimate the fractional precipitation upon cooldown. Optical reflectivity and videography provided much faster temporal resolution. Both the growth kinetics and the fractional isothermal precipitation were found to be governed by the C2H2 partial pressure in the CVD pulse for a given film thickness and temperature, with up to ~94% of graphene growth occurring isothermally within 1 second at 800 °C at high partial pressures. At lower partial pressures, isothermal graphene growth is shown to continue 10 seconds after the gas pulse. These flux-dependent growth kinetics are described in the context of a dissolution/precipitation model, where carbon rapidly dissolves into the Ni film and later precipitates driven by gradients in the chemical potential. The combination of pulsed-CVD and real-time optical diagnostics opens new opportunities to understand and control the fast, sub-second growth of graphene on various substrates at high temperatures.The kinetics and mechanisms of graphene growth on Ni films at 720-880 °C have been measured using fast pulses of acetylene and real-time optical diagnostics. In situ UV-Raman spectroscopy was used to unambiguously detect isothermal graphene growth at high temperatures, measure the growth kinetics with ~1 s temporal resolution, and estimate the fractional precipitation upon cooldown. Optical reflectivity and videography provided much faster temporal resolution. Both the growth kinetics and the fractional isothermal precipitation were found to be governed by the C2H2 partial pressure in the CVD pulse for a given film thickness and temperature, with up to ~94% of graphene growth occurring isothermally

  5. The allelopathic effects of invasive plant Solidago canadensis on seed germination and growth of Lactuca sativa enhanced by different types of acid deposition.

    Science.gov (United States)

    Wang, Congyan; Xiao, Hongguang; Zhao, Lulu; Liu, Jun; Wang, Lei; Zhang, Fei; Shi, Yanchun; Du, Daolin

    2016-04-01

    Invasive species can exhibit allelopathic effects on native species. Meanwhile, the types of acid deposition are gradually changing. Thus, the allelopathic effects of invasive species on seed germination and growth of native species may be altered or even enhanced under conditions with diversified acid deposition. This study aims to assess the allelopathic effects (using leaves extracts) of invasive plant Solidago canadensis on seed germination and growth of native species Lactuca sativa treated with five types of acid deposition with different SO4(2-) to NO3(-) ratios (1:0, sulfuric acid; 5:1, sulfuric-rich acid; 1:1, mixed acid; 1:5, nitric-rich acid; 0:1, nitric acid). Solidago canadensis leaf extracts exhibited significantly allelopathic effects on germination index, vigor index, and germination rate index of L. sativa. High concentration of S. canadensis leaf extracts also similarly exhibited significantly allelopathic effects on root length of L. sativa. This may be due to that S. canadensis could release allelochemicals and then trigger allelopathic effects on seed germination and growth of L. sativa. Acid deposition exhibited significantly negative effects on seedling biomass, root length, seedling height, germination index, vigor index, and germination rate index of L. sativa. This may be ascribed to the decreased soil pH values mediated by acid deposition which could produce toxic effects on seedling growth. Sulfuric acid deposition triggered more toxic effects on seedling biomass and vigor index of L. sativa than nitric acid deposition. This may be attributing to the difference in exchange capacity with hydroxyl groups (OH(-)) between SO4(2-) and NO3(-) as well as the fertilizing effects mediated by nitric deposition. All types of acid deposition significantly enhanced the allelopathic effects of S. canadensis on root length, germination index, vigor index, and germination rate index of L. sativa. This may be due to the negatively synergistic effects of

  6. Pengaruh Capital Adequacy Ratio (CAR, Beban Operasional Pendapatan Operasional (BOPO, Return on Asset (ROA dan Net Interest Margin (NIM terhadap Financing Deposit Ratio (FRD di PT. BPRS Bhakti Sumekar Sumenep (Periode 2011-2015

    Directory of Open Access Journals (Sweden)

    Cholida Noerainon

    2016-06-01

    Full Text Available The Bank is an industry whose business activities relying on public confidence so that the health of banks is done by maintaining the quality so that the bank can meet its obligations and maintain its performance. The purpose bank will be realized if the bank is able to significantly improve their performance optimal. To be able to function properly, the banks should have enough capital, maintaining its asset quality with a good, well-managed and operated by the precautionary principle thus generate enough profit to maintain the continuity of its business and maintain its liquidity so that it can meet its obligations at any time. the purpose of this study is the first: To determine the effect of the Capital Adequacy Ratio (CAR, Operating Expenses Towards Operating Income (OEOI, Return on Assets (ROA and Net Interest Margin (NIM simultaneously to the Financial to Deposit Ratio (FDR PT. BPRS Bhakti Sumekar Sumenep. Second: To determine the effect of the Capital Adequacy Ratio (CAR, Operating Expenses Towards Operating Income  (OEOI, Return on Assets (ROA and Net Interest Margin (NIM partially on Financial to Deposit Ratio (FDR PT. BPRS Bhakti Sumekar Sumenep. Third: To determine which variables are the most dominant influencing on Financial to Deposit Ratio (FDR at PT. BPRS Bhakti Sumekar Sumenep. In this research uses quantitative methods with the technique of multiple linear regression analysis with the help of SPSS analysis tools, while proving the hypothesis using a calculation T test and F test. The data used is secondary data namely quarterly publication report documentation results. The research results shows that the variables CAR, OEOI, ROA and NIM simultaneously no effect  towards FDR PT. BPRS Bhakti Sumekar Sumenep because Sig. > 0.05 and the value of Fcount

  7. Perfect alignment and preferential orientation of nitrogen-vacancy centers during chemical vapor deposition diamond growth on (111) surfaces

    International Nuclear Information System (INIS)

    Michl, Julia; Zaiser, Sebastian; Jakobi, Ingmar; Waldherr, Gerald; Dolde, Florian; Neumann, Philipp; Wrachtrup, Jörg; Teraji, Tokuyuki; Doherty, Marcus W.; Manson, Neil B.; Isoya, Junichi

    2014-01-01

    Synthetic diamond production is a key to the development of quantum metrology and quantum information applications of diamond. The major quantum sensor and qubit candidate in diamond is the nitrogen-vacancy (NV) color center. This lattice defect comes in four different crystallographic orientations leading to an intrinsic inhomogeneity among NV centers, which is undesirable in some applications. Here, we report a microwave plasma-assisted chemical vapor deposition diamond growth technique on (111)-oriented substrates, which yields perfect alignment (94% ± 2%) of as-grown NV centers along a single crystallographic direction. In addition, clear evidence is found that the majority (74% ± 4%) of the aligned NV centers were formed by the nitrogen being first included in the (111) growth surface and then followed by the formation of a neighboring vacancy on top. The achieved homogeneity of the grown NV centers will tremendously benefit quantum information and metrology applications

  8. Gold catalytic Growth of Germanium Nanowires by chemical vapour deposition method

    Directory of Open Access Journals (Sweden)

    M. Zahedifar

    2013-03-01

    Full Text Available Germanium nanowires (GeNWs were synthesized using chemical vapor deposition (CVD based on vapor–liquid–solid (VLS mechanism with Au nanoparticles as catalyst and germanium tetrachloride (GeCl4 as a precursor of germanium. Au catalysts were deposited on silicon wafer as a thin film, firstly by sputtering technique and secondly by submerging the silicon substrates in Au colloidal solution, which resulted in Au nanoparticles with different sizes. GeNWs were synthesized at 400 °C, which is a low temperature for electrical device fabrication. Effect of different parameters such as Au nanoparticles size, carrier gas (Ar flow and mixture of H2 with the carrier gas on GeNWs diameter and shape was studied by SEM images. The chemical composition of the nanostructure was also examined by energy dispersive X-ray spectroscopy (EDS.

  9. Growth of BaTiO3-PVDF composite thick films by using aerosol deposition

    Science.gov (United States)

    Cho, Sung Hwan; Yoon, Young Joon

    2016-01-01

    Barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite thick films were grown by using aerosol deposition at room temperature with BaTiO3 and PVDF powders. To produce a uniform composition in ceramic and polymer composite films, which show a substantial difference in specific gravity, we used PVDF-coated BaTiO3 powders as the starting materials. An examination of the microstructure confirmed that the BaTiO3 were well distributed in the PVDF matrix in the form of a 0 - 3 compound. The crystallite size in the BaTiO3-PVDF composite thick films was 5 ˜ 50 times higher than that in pure BaTiO3 thick films. PVDF plays a role in suppressing the fragmentation of BaTiO3 powder during the aerosol deposition process and in controlling the relative permittivity.

  10. Growth parameter enhancement for MoS{sub 2} thin films synthesized by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Serna, Martha I.; Higgins, Marissa; Quevedo-Lopez, Manuel A. [Materials Science and Engineering Department, The University of Texas at Dallas, 800 W Campbell Road RL 10, Richardson TX 75080 (United States); Moreno, Salvador [Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080 (United States); Choi, Hyunjoo [Department of Advanced Materials Engineering, Kookmin University, Jeongneung-dong Seongbuk-gu, Seoul 136-702 (Korea, Republic of); Minary-Jolandan, Majid [Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080 (United States); Alan MacDiarmid Nanotech Institute, The University of Texas at Dallas, 800 W Campbell Road RL 10, Richardson TX 75080 (United States)

    2016-12-15

    Two-dimensional materials such as graphene and MoS{sub 2} have been the main focus of intense research efforts over the past few years. The most common method of exfoliating these materials, although efficient for lab-scale experiments, is not acceptable for large area and practical applications. Here, we report the deposition of MoS{sub 2} layered films on amorphous (SiO{sub 2}) and crystalline substrates (sapphire) using a pulsed laser deposition (PLD) method. Increased substrate temperature (∝700 C) and laser energy density (>530 mJ /cm{sup 2}) promotes crystalline MoS{sub 2} films < 20 nm, as demonstrated by fast Fourier transform (FFT) and transmission electron microscopy (TEM). The method reported here opens the possibility for large area layered MoS{sub 2} films by using a laser ablation processes. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Multiscale modeling, simulations, and experiments of coating growth on nanofibers. Part II. Deposition

    International Nuclear Information System (INIS)

    Buldum, A.; Clemons, C.B.; Dill, L.H.; Kreider, K.L.; Young, G.W.; Zheng, X.; Evans, E.A.; Zhang, G.; Hariharan, S.I.

    2005-01-01

    This work is Part II of an integrated experimental/modeling investigation of a procedure to coat nanofibers and core-clad nanostructures with thin-film materials using plasma-enhanced physical vapor deposition. In the experimental effort, electrospun polymer nanofibers are coated with aluminum materials under different operating conditions to observe changes in the coating morphology. This procedure begins with the sputtering of the coating material from a target. Part I [J. Appl. Phys. 98, 044303 (2005)] focused on the sputtering aspect and transport of the sputtered material through the reactor. That reactor level model determines the concentration field of the coating material. This field serves as input into the present species transport and deposition model for the region surrounding an individual nanofiber. The interrelationships among processing factors for the transport and deposition are investigated here from a detailed modeling approach that includes the salient physical and chemical phenomena. Solution strategies that couple continuum and atomistic models are used. At the continuum scale, transport dynamics near the nanofiber are described. At the atomic level, molecular dynamics (MD) simulations are used to study the deposition and sputtering mechanisms at the coating surface. Ion kinetic energies and fluxes are passed from the continuum sheath model to the MD simulations. These simulations calculate sputtering and sticking probabilities that in turn are used to calculate parameters for the continuum transport model. The continuum transport model leads to the definition of an evolution equation for the coating-free surface. This equation is solved using boundary perturbation and level set methods to determine the coating morphology as a function of operating conditions

  12. New deposition processes for the growth of oxide and nitride thin films

    International Nuclear Information System (INIS)

    Apen, E.A.; Atagi, L.M.; Barbero, R.S.; Espinoza, B.F.; Hubbard, K.M.; Salazar, K.V.; Samuels, J.A.; Smith, D.C.; Hoffman, D.M.

    1998-01-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The goal of this effort is to study the use of homoleptic metal amido compounds as precursors for chemical vapor deposition (CVD). The amides offer potential for the deposition of a variety of important materials at low temperatures. The establishment of these precursor compounds will enhance the ability to exploit the properties of advanced materials in numerous coatings applications. Experiments were performed to study the reactivity of Sn[NMe 2 ] 4 with oxygen. The data demonstrated that gas-phase insertion of oxygen into the Sn-N bond, leading to a reactive intermediate, plays an important role in tin oxide deposition. Several CVD processes for technologically important materials were developed using the amido precursor complexes. These included the plasma enhanced CVD of TiN and Zr 3 N 4 , and the thermal CVD of GaN and AlN. Quality films were obtained in each case, demonstrating the potential of the amido compounds as CVD precursors

  13. Comparison of diamond growth with different gas mixtures in microwave plasma asssited chemical vapor deposition (MWCVD

    Directory of Open Access Journals (Sweden)

    Corat Evaldo J.

    2003-01-01

    Full Text Available In this work we study the influence of oxygen addition to several halocarbon-hydrogen gas systems. Diamond growth have been performed in a high power density MWCVD reactor built in our laboratory. The growth experiments are monitored by argon actinometry as a reference to plasma temperature and atomic hydrogen production, and by mass spectrometry to compare the exhaust gas composition. Atomic hydrogen actinometry revealed that the halogen presence in the gas phase is responsible for a considerable increase of atomic hydrogen concentration in the gas phase. Mass spectrometry shows similar results for all gas mixtures tested. Growth studies with oxygen addition to CF4/H2, CCl4/H2, CCl2F2/H2 and CH3Cl/H2 reveals that oxygen increases the carbon solubility in the gas phase but no better diamond growth conditions were found. Halogens are not, per se, eligible for diamond growth. All the possible advantages, as the higher production of atomic hydrogen, have been suppressed by the low carbon solubility in the gas phase, even when oxygen is added. The diamond growth with small amount of CF4 added to CH4/H2 mixture is not aggressive to the apparatus but brings several advantages to the process.

  14. Catalyst-free growth and tailoring morphology of zinc oxide nanostructures by plasma-enhanced deposition at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W. Z. [Quanzhou Normal University, Key Laboratory of Information Functional Material for Fujian Higher Education, College of Physics & Information Engineering (China); Wang, B. B. [Chongqing University of Technology, College of Chemical Engineering (China); Qu, Y. Z.; Huang, X. [Xiamen University, College of Energy, Xiang’an Campus (China); Ostrikov, K. [Queensland University of Technology, School of Chemistry, Physics and Mechanical Engineering (Australia); Levchenko, I.; Xu, S. [Nanyang Technological University, Plasma Sources and Applications Centre, National Institute of Education (Singapore); Cheng, Q. J., E-mail: qijin.cheng@xmu.edu.cn [Xiamen University, College of Energy, Xiang’an Campus (China)

    2017-03-15

    ZnO nanostructures were grown under different deposition conditions from Zn films pre-deposited onto Si substrates in O{sub 2}-Ar plasma, ignited in an advanced custom-designed plasma-enhanced horizontal tube furnace deposition system. The morphology and structure of the synthesized ZnO nanostructures were systematically and extensively investigated by scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. It is shown that the morphology of ZnO nanostructures changes from the hybrid ZnO/nanoparticle and nanorod system to the mixture of ZnO nanosheets and nanorods when the growth temperature increases, and the density of ZnO nanorods increases with the increase of oxygen flow rate. The formation of ZnO nanostructures was explained in terms of motion of Zn atoms on the Zn nanoparticle surfaces, and to the local melting of Zn nanoparticles or nanosheets. Moreover, the photoluminescence properties of ZnO nanostructures were studied, and it was revealed that the photoluminescence spectrum features two strong ultraviolet bands at about 378 and 399 nm and a series of weak blue bands within a range of 440–484 nm, related to the emissions of free excitons, near-band edge, and defects of ZnO nanostructures. The obtained results enrich our knowledge on the synthesis of ZnO-based nanostructures and contribute to the development of ZnO-based optoelectronic devices.

  15. Catalyst-free growth and tailoring morphology of zinc oxide nanostructures by plasma-enhanced deposition at low temperature

    International Nuclear Information System (INIS)

    Chen, W. Z.; Wang, B. B.; Qu, Y. Z.; Huang, X.; Ostrikov, K.; Levchenko, I.; Xu, S.; Cheng, Q. J.

    2017-01-01

    ZnO nanostructures were grown under different deposition conditions from Zn films pre-deposited onto Si substrates in O 2 -Ar plasma, ignited in an advanced custom-designed plasma-enhanced horizontal tube furnace deposition system. The morphology and structure of the synthesized ZnO nanostructures were systematically and extensively investigated by scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. It is shown that the morphology of ZnO nanostructures changes from the hybrid ZnO/nanoparticle and nanorod system to the mixture of ZnO nanosheets and nanorods when the growth temperature increases, and the density of ZnO nanorods increases with the increase of oxygen flow rate. The formation of ZnO nanostructures was explained in terms of motion of Zn atoms on the Zn nanoparticle surfaces, and to the local melting of Zn nanoparticles or nanosheets. Moreover, the photoluminescence properties of ZnO nanostructures were studied, and it was revealed that the photoluminescence spectrum features two strong ultraviolet bands at about 378 and 399 nm and a series of weak blue bands within a range of 440–484 nm, related to the emissions of free excitons, near-band edge, and defects of ZnO nanostructures. The obtained results enrich our knowledge on the synthesis of ZnO-based nanostructures and contribute to the development of ZnO-based optoelectronic devices.

  16. Exploring the Potential use of Photo-Selective Nets for Fruit Growth Regulation in Apple Explorando el uso Potencial de Mallas Foto-Selectivas para la Regulación del Crecimiento de Fruto en Manzano

    Directory of Open Access Journals (Sweden)

    Richard M Bastías

    2012-06-01

    Full Text Available The effect of shading (i.e. reduction of sunlight availability on fruit growth physiology has been widely studied in apple (Malus domestica Borkh., but little knowledge exist about fruit growth responses to changes in the light spectrum. The aim of the present research was to study the effect of use of colored nets with differential sunlight transmission in the blue (B, 400-500 nm, red (R, 600-700 nm and far-red (FR, 700-800 nm spectra on apple fruit growth and physiological associated responses. Three year old 'Fuji' apple trees were covered with 40% photo-selective blue and red shade nets, 40% neutral grey shade net, and 20% neutral white net as control. Red and blue net reduced in the same proportion (27% the photosynthetically active radiation with respect to control. However, blue net increased by 30% and reduced by 10% the B:R and R:FR the light relations, respectively. Maximal fruit growth rate under blue and grey nets was 15-20% greater than control. Fruit weight under blue net was 17% greater than control, but no significant differences in fruit weight were found among red net and control. Leaf photosynthesis and total leaf area under blue net were 28% and 30% higher than control, respectively; with ensuing positive effect on tree net C assimilation rate and total dry matter production. Results suggest that shifting the B, R, and FR light composition with photo-selective nets could be a useful tool to manipulate the photosynthetic and morphogenetic process regulating the carbohydrate availability for apple fruit growth.El efecto del sombreado (i.e. reducción de la cantidad de luz solar sobre la fisiología de crecimiento de fruto ha sido ampliamente estudiado en manzano (Malus domestica Borkh., pero existe poco conocimiento sobre respuestas de crecimiento del fruto a cambios en el espectro de la luz. El objetivo de la presente investigación fue estudiar el efecto del uso de mallas de color con transmisión diferencial de la luz en el

  17. An ultrahigh vacuum, low-energy ion-assisted deposition system for III-V semiconductor film growth

    Science.gov (United States)

    Rohde, S.; Barnett, S. A.; Choi, C.-H.

    1989-06-01

    A novel ion-assisted deposition system is described in which the substrate and growing film can be bombarded with high current densities (greater than 1 mA/sq cm) of very low energy (10-200 eV) ions. The system design philosophy is similar to that used in III-V semiconductor molecular-beam epitaxy systems: the chamber is an all-metal ultrahigh vacuum system with liquid-nitrogen-cooled shrouds, Knudsen-cell evaporation sources, a sample insertion load-lock, and a 30-kV reflection high-energy electron diffraction system. III-V semiconductor film growth is achieved using evaporated group-V fluxes and group-III elemental fluxes sputtered from high-purity targets using ions extracted from a triode glow discharge. Using an In target and an As effusion cell, InAs deposition rates R of 2 microns/h have been obtained. Epitaxial growth of InAs was observed on both GaSb(100) and Si(100) substrates.

  18. Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

    Directory of Open Access Journals (Sweden)

    Tyagi Renu

    2009-01-01

    Full Text Available Abstract Self-assembled InAs quantum dots (QDs were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs. The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.

  19. X-ray photoelectron spectroscopy study on Fe and Co catalysts during the first stages of ethanol chemical vapor deposition for single-walled carbon nanotube growth

    NARCIS (Netherlands)

    Oida, S.; McFeely, F.R.; Bol, A.A.

    2011-01-01

    Optimized chemical vapor deposition processes for single-walled carbon nanotube (SWCNT) can lead to the growth of dense, vertically aligned, mm-long forests of SWCNTs. Precise control of the growth process is however still difficult, mainly because of poor understanding of the interplay between

  20. Process control by optical emission spectroscopy during growth of a-C:H from a CH4 plasma by plasma-enhanced chemical vapour deposition

    DEFF Research Database (Denmark)

    Barholm-Hansen, C; Bentzon, MD; Vigild, Martin Etchells

    1994-01-01

    During the growth of a-C:H thin films for tribological applications, the characteristic optical emission from a CH4 plasma was used to estimate growth conditions such as the degree of dissociation of the feed gas, the deposition rate and the presence of impurities. Films were fabricated with vari...

  1. High Growth Rate Deposition of Hydrogenated Amorphous Silicon-Germanium Films and Devices Using ECR-PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yong [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    Hydrogenated amorphous silicon germanium films (a-SiGe:H) and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large-scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert-gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. Preferential attachment of hydrogen to silicon, clustering of Ge and Si, and columnar structure and buried dihydride radicals make the film intolerably bad. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with a small amount of H2, was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, I-V curve, and quantum efficiency were characterized during the process of pursuing good materials. The microstructure of the a-(Si,Ge):H material was probed by Fourier-Transform Infrared spectroscopy. They found that the advantages of using helium as the main plasma species are: (1) high growth rate--the energetic helium ions break the reactive gas more efficiently than hydrogen ions; (2) homogeneous growth--heavy helium ions impinging on the surface promote the surface mobility of the reactive radicals, so that heteroepitaxy growth as clustering of Ge and Si, columnar structure are

  2. Directed growth of graphene nanomesh in purified argon via chemical vapor deposition.

    Science.gov (United States)

    Sun, Haibin; Fu, Can; Shen, Xia; Yang, Wenchao; Guo, Pengfei; Lu, Yang; Luo, Yongsong; Yu, Benhai; Wang, Xiaoge; Wang, Chunlei; Xu, Junqi; Liu, Jiangfeng; Song, Fengqi; Wang, Guanghou; Wan, Jianguo

    2017-06-16

    Graphene nanomeshes (GNMs), new graphene nanostructures with tunable bandgaps, are potential building blocks for future electronic or photonic devices, and energy storage and conversion materials. In previous works, GNMs have been successfully prepared on Cu foils by the H 2 etching effect. In this paper, we investigated the effect of Ar on the preparation of GNMs, and how the mean density and shape of them vary with growth time. In addition, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (TEM) revealed the typical hexagonal structure of GNM. Atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) indicated that large copper oxide nanoparticles produced by oxidization in purified Ar can play an essential catalytic role in preparing GNMs. Then, we exhibited the key reaction details for each growth process and proposed a growth mechanism of GNMs in purified Ar.

  3. 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

  4. Graphene growth by transfer-free chemical vapour deposition on a cobalt layer

    Science.gov (United States)

    Macháč, Petr; Hejna, Ondřej; Slepička, Petr

    2017-01-01

    The contribution deals with the preparation of graphene films by a transfer-free chemical vapour deposition process utilizing a thin cobalt layer. This method allows growing graphene directly on a dielectric substrate. The process was carried out in a cold-wall reactor with methane as carbon precursor. We managed to prepare bilayer graphene. The best results were obtained for a structure with a cobalt layer with a thickness of 50 nm. The quality of prepared graphene films and of the number of graphene layers were estimated using Raman spectroscopy. with a minimal dots diameter of 180 nm and spacing of 1000 nm were successfully developed.

  5. Parametric Investigation of the Isothermal Kinetics of Growth of Graphene on a Nickel Catalyst in the Process of Chemical Vapor Deposition of Hydrocarbons

    Science.gov (United States)

    Futko, S. I.; Shulitskii, B. G.; Labunov, V. A.; Ermolaeva, E. M.

    2016-11-01

    A kinetic model of isothermal synthesis of multilayer graphene on the surface of a nickel foil in the process of chemical vapor deposition, on it, of hydrocarbons supplied in the pulsed regime is considered. The dependences of the number of graphene layers formed and the time of their growth on the temperature of the process, the concentration of acetylene, and the thickness of the nickel foil were calculated. The regime parameters of the process of chemical vapor deposition, at which single-layer graphene and bi-layer graphene are formed, were determined. The dynamics of growth of graphene domains at chemical-vapor-deposition parameters changing in wide ranges was investigated. It is shown that the time dependences of the rates of growth of single-layer graphene and bi-layer graphene are nonlinear in character and that they are determined by the kinetics of nucleation and growth of graphene and the diffusion flow of carbon atoms in the nickel foil.

  6. Growth and electrical properties of AlOx grown by mist chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Toshiyuki Kawaharamura

    2013-03-01

    Full Text Available Aluminum oxide (AlOx thin films were grown using aluminum acetylacetonate (Al(acac3 as a source solute by mist chemical vapor deposition (mist CVD. The AlOx thin films grown at temperatures above 400°C exhibited a breakdown field (EBD over 6 MV/cm and a dielectric constant (κ over 6. It is suggested that residual OH bonding in the AlOx thin films grown at temperatures below 375°C caused degradation of the breakdown field (EBD. With FC type mist CVD, the reaction proceeded efficiently (Ea = 22–24 kJ/mol because the solvent, especially H2O, worked as a stronger oxygen source. The AlOx film could be grown at 450°C with a high deposition rate (23 nm/min and smooth surface (RMS = 1.5 nm. Moreover, the AlOx thin films grown by mist CVD had excellent practicality as insulators because the gate leakage current (IG of the oxide thin film transistor (TFT with an IGZO/AlOx stack was suppressed below 1 pA at a gate voltage (VG of 20 V.

  7. Influence of the Hydrothermal Method Growth Parameters on the Zinc Oxide Nanowires Deposited on Several Substrates

    Directory of Open Access Journals (Sweden)

    Concepción Mejía-García

    2014-01-01

    Full Text Available We report the synthesis of ZnO nanowires grown on several substrates (PET, glass, and Si using a two-step process: (a preparation of the seed layer on the substrate by spin coating, from solutions of zinc acetate dihydrate and 1-propanol, and (b growth of the ZnO nanostructures by dipping the substrate in an equimolar solution of zinc nitrate hexahydrate and hexamethylenetetramine. Subsequently, films were thermally treated with a commercial microwave oven (350 and 700 W for 5, 20, and 35 min. The ZnO nanowires obtained were characterized structurally, morphologically, and optically using XRD, SEM, and UV-VIS transmission, respectively. XRD patterns spectra revealed the presence of Zn(OH2 on the films grown on glass and Si substrates. A preferential orientation along c-axis directions for films grown on PET substrate was observed. An analysis by SEM revealed that the growth of the ZnO nanowires on PET and glass is better than the growth on Si when the same growth parameters are used. On glass substrates, ZnO nanowires less than 50 nm in diameter and between 200 nm and 1200 nm in length were obtained. The ZnO nanowires band gap energy for the films grown on PET and glass was obtained from optical transmission spectra.

  8. 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

  9. Microwave plasma-enhanced chemical vapour deposition growth of carbon nanostructures

    Directory of Open Access Journals (Sweden)

    Shivan R. Singh

    2010-05-01

    Full Text Available The effect of various input parameters on the production of carbon nanostructures using a simple microwave plasma-enhanced chemical vapour deposition technique has been investigated. The technique utilises a conventional microwave oven as the microwave energy source. The developed apparatus is inexpensive and easy to install and is suitable for use as a carbon nanostructure source for potential laboratory-based research of the bulk properties of carbon nanostructures. A result of this investigation is the reproducibility of specific nanostructures with the variation of input parameters, such as carbon-containing precursor and support gas flow rate. It was shown that the yield and quality of the carbon products is directly controlled by input parameters. Transmission electron microscopy and scanning electron microscopy were used to analyse the carbon products; these were found to be amorphous, nanotubes and onion-like nanostructures.

  10. Growth of epitaxial Pb(Zr,Ti)O3 films by pulsed laser deposition

    Science.gov (United States)

    Lee, J.; Safari, A.; Pfeffer, R. L.

    1992-10-01

    Lead zirconate titanate (PZT) thin films with a composition near the morphotropic phase boundary have been grown on MgO (100) and Y1Ba2Cu3Ox (YBCO) coated MgO substrates. Substrate temperature and oxygen pressure were varied to achieve ferroelectric films with a perovskite structure. Films grown on MgO had the perovskite structure with an epitaxial relationship with the MgO substrate. On the other hand, films grown on the YBCO/MgO substrate had an oriented structure to the surface normal with a misorientation in the plane parallel to the surface. The measured dielectric constant and loss tangent at 1 kHz were 670 and 0.05, respectively. The remnant polarization and coercive field were 42 μC/cm2 and 53 kV/cm. A large internal bias field (12 kV/cm) was observed in the as-deposited state of the undoped PZT films.

  11. Growth, Properties and Applications of Mo Ox Thin-Films Deposited by Reactive Sputtering

    DEFF Research Database (Denmark)

    Fernandes Cauduro, André Luis

    properties of metal-oxide thin films through surface defect engineering is vital to fine-tune their optoelectronic properties, and thus also their integration in novel optoelectronic devices. In this work, MoOx thin-films with various different phases and compositions were prepared by direct-current reactive...... molecules DBP and C70 are also covered in this work. The devices show interesting characteristics for very thin layers of the as-deposited MoOx films, displaying similar device efficiencies as those of in situ prepared MoOx thin-films formed from thermal evaporation. For the annealed MoOx films......Transition metal-oxide (TMOs) thin-films are commonly used in optoelectronic devices such as in photovoltaics and light emitting diodes, using both organic, inorganic and hybrid technologies. In such devices, TMOs typically act as an interfacial layer, where its functionality is to facilitate hole...

  12. Controllable growth of nanostructured carbon from coal tar pitch by chemical vapor deposition

    International Nuclear Information System (INIS)

    Liu Xuguang; Yang Yongzhen; Ji Weiyun; Liu Hongyan; Zhang Chunyi; Xu Bingshe

    2007-01-01

    The direct synthesis of vapor grown carbon fibers with different diameters was achieved by the pyrolysis of coal tar pitch by chemical vapor deposition. The products were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The experimental results demonstrated that ferrocene content, reaction temperature and Ar flow rate strongly influenced the yield and nature of nanostructured carbon materials, pure carbon microbeads, with diameter distribution ranging from 450 to 650 nm, were also obtained in the absence of catalyst, uniform and straight carbon nanofibers with the outer diameter of about 115 nm were obtained and curl and thick carbon fibers with narrow diameter distribution of 300-350 nm were produced

  13. Atomic layer deposition on polymer based flexible packaging materials: Growth characteristics and diffusion barrier properties

    International Nuclear Information System (INIS)

    Kaeaeriaeinen, Tommi O.; Maydannik, Philipp; Cameron, David C.; Lahtinen, Kimmo; Johansson, Petri; Kuusipalo, Jurkka

    2011-01-01

    One of the most promising areas for the industrial application of atomic layer deposition (ALD) is for gas barrier layers on polymers. In this work, a packaging material system with improved diffusion barrier properties has been developed and studied by applying ALD on flexible polymer based packaging materials. Nanometer scale metal oxide films have been applied to polymer-coated papers and their diffusion barrier properties have been studied by means of water vapor and oxygen transmission rates. The materials for the study were constructed in two stages: the paper was firstly extrusion coated with polymer film, which was then followed by the ALD deposition of oxide layer. The polymers used as extrusion coatings were polypropylene, low and high density polyethylene, polylactide and polyethylene terephthalate. Water vapor transmission rates (WVTRs) were measured according to method SCAN-P 22:68 and oxygen transmission rates (O 2 TRs) according to a standard ASTM D 3985. According to the results a 10 nm oxide layer already decreased the oxygen transmission by a factor of 10 compared to uncoated material. WVTR with 40 nm ALD layer was better than the level currently required for most common dry flexible packaging applications. When the oxide layer thickness was increased to 100 nm and above, the measured WVTRs were limited by the measurement set up. Using an ALD layer allowed the polymer thickness on flexible packaging materials to be reduced. Once the ALD layer was 40 nm thick, WVTRs and O 2 TRs were no longer dependent on polymer layer thickness. Thus, nanometer scale ALD oxide layers have shown their feasibility as high quality diffusion barriers on flexible packaging materials.

  14. Atomic layer deposition on polymer based flexible packaging materials: Growth characteristics and diffusion barrier properties

    Energy Technology Data Exchange (ETDEWEB)

    Kaeaeriaeinen, Tommi O., E-mail: tommi.kaariainen@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Maydannik, Philipp, E-mail: philipp.maydannik@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Cameron, David C., E-mail: david.cameron@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Lahtinen, Kimmo, E-mail: kimmo.lahtinen@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland); Johansson, Petri, E-mail: petri.johansson@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland); Kuusipalo, Jurkka, E-mail: jurkka.kuusipalo@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland)

    2011-03-01

    One of the most promising areas for the industrial application of atomic layer deposition (ALD) is for gas barrier layers on polymers. In this work, a packaging material system with improved diffusion barrier properties has been developed and studied by applying ALD on flexible polymer based packaging materials. Nanometer scale metal oxide films have been applied to polymer-coated papers and their diffusion barrier properties have been studied by means of water vapor and oxygen transmission rates. The materials for the study were constructed in two stages: the paper was firstly extrusion coated with polymer film, which was then followed by the ALD deposition of oxide layer. The polymers used as extrusion coatings were polypropylene, low and high density polyethylene, polylactide and polyethylene terephthalate. Water vapor transmission rates (WVTRs) were measured according to method SCAN-P 22:68 and oxygen transmission rates (O{sub 2}TRs) according to a standard ASTM D 3985. According to the results a 10 nm oxide layer already decreased the oxygen transmission by a factor of 10 compared to uncoated material. WVTR with 40 nm ALD layer was better than the level currently required for most common dry flexible packaging applications. When the oxide layer thickness was increased to 100 nm and above, the measured WVTRs were limited by the measurement set up. Using an ALD layer allowed the polymer thickness on flexible packaging materials to be reduced. Once the ALD layer was 40 nm thick, WVTRs and O{sub 2}TRs were no longer dependent on polymer layer thickness. Thus, nanometer scale ALD oxide layers have shown their feasibility as high quality diffusion barriers on flexible packaging materials.

  15. 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.

  16. Evaluation of Alternative Atomistic Models for the Incipient Growth of ZnO by Atomic Layer Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Manh-Hung; Tian, Liang; Chaker, Ahmad; Skopin, Evgenii; Cantelli, Valentina; Ouled, Toufik; Boichot, Raphaël; Crisci, Alexandre; Lay, Sabine; Richard, Marie-Ingrid; Thomas, Olivier; Deschanvres, Jean-Luc; Renevier, Hubert; Fong, Dillon; Ciatto, Gianluca

    2017-03-20

    ZnO thin films are interesting for applications in several technological fields, including optoelectronics and renewable energies. Nanodevice applications require controlled synthesis of ZnO structures at nanometer scale, which can be achieved via atomic layer deposition (ALD). However, the mechanisms governing the initial stages of ALD had not been addressed until very recently. Investigations into the initial nucleation and growth as well as the atomic structure of the heterointerface are crucial to optimize the ALD process and understand the structure-property relationships for ZnO. We have used a complementary suite of in situ synchrotron x-ray techniques to investigate both the structural and chemical evolution during ZnO growth by ALD on two different substrates, i.e., SiO2 and Al2O3, which led us to formulate an atomistic model of the incipient growth of ZnO. The model relies on the formation of nanoscale islands of different size and aspect ratio and consequent disorder induced in the Zn neighbors' distribution. However, endorsement of our model requires testing and discussion of possible alternative models which could account for the experimental results. In this work, we review, test, and rule out several alternative models; the results confirm our view of the atomistic mechanisms at play, which influence the overall microstructure and resulting properties of the final thin film.

  17. 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.)

  18. Growth of different phases and morphological features of MnS thin films by chemical bath deposition: Effect of deposition parameters and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Hannachi, Amira, E-mail: amira.hannachi88@gmail.com; Maghraoui-Meherzi, Hager

    2017-03-15

    Manganese sulfide thin films have been deposited on glass slides by chemical bath deposition (CBD) method. The effects of preparative parameters such as deposition time, bath temperature, concentration of precursors, multi-layer deposition, different source of manganese, different complexing agent and thermal annealing on structural and morphological film properties have been investigated. The prepared thin films have been characterized using the X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). It exhibit the metastable forms of MnS, the hexagonal γ-MnS wurtzite phase with preferential orientation in the (002) plane or the cubic β-MnS zinc blende with preferential orientation in the (200) plane. Microstructural studies revealed the formation of MnS crystals with different morphologies, such as hexagons, spheres, cubes or flowers like. - Graphical Abstract: We report the preparation of different phases of manganese sulfide thin films (γ, β and α-MnS) by chemical bath deposition method. The effects of deposition parameters such as deposition time and temperature, concentrations of precursors and multi-layer deposition on MnS thin films structure and morphology were investigated. The influence of thermal annealing under nitrogen atmosphere at different temperature on MnS properties was also studied. Different manganese precursors as well as different complexing agent were also used. - Highlights: • γ and β-MnS films were deposited on substrate using the chemical bath deposition. • The effect of deposition parameters on MnS film properties has been investigated. • Multi-layer deposition was also studied to increase film thickness. • The effect of annealing under N{sub 2} at different temperature was investigated.

  19. 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.

  20. Role of VI/II ratio on the growth of ZnO nanostructures using chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Urgessa, Z.N., E-mail: zelalem.urgessa@nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Oluwafemi, O.S. [Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha Campus, Private Bag XI, 5117 (South Africa); Botha, J.R. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    In this paper the growth process and morphological evolution of ZnO nanostructures were investigated in a series of experiments using chemical bath deposition. The experimental results indicate that the morphological evolution depends on the reaction conditions, particularly on OH{sup -} to Zn{sup 2+} ratio (which directly affects the pH). For low VI/II ratios, quasi-spherical nanoparticles of an average diameter 30 nm are obtained, whereas for larger VI/II ratios, nanorods with an average diameter less than 100 nm are produced, which indicates that by systematically controlling the VI/II ratio, it is possible to produce different shapes and sizes of ZnO nanostructures. A possible mechanism for the nanostructural change of the as-synthesized ZnO from particle to rod was elucidated based on the relative densities of H{sup +} and OH{sup -} in the solution.

  1. Role of VI/II ratio on the growth of ZnO nanostructures using chemical bath deposition

    International Nuclear Information System (INIS)

    Urgessa, Z.N.; Oluwafemi, O.S.; Botha, J.R.

    2012-01-01

    In this paper the growth process and morphological evolution of ZnO nanostructures were investigated in a series of experiments using chemical bath deposition. The experimental results indicate that the morphological evolution depends on the reaction conditions, particularly on OH − to Zn 2+ ratio (which directly affects the pH). For low VI/II ratios, quasi-spherical nanoparticles of an average diameter 30 nm are obtained, whereas for larger VI/II ratios, nanorods with an average diameter less than 100 nm are produced, which indicates that by systematically controlling the VI/II ratio, it is possible to produce different shapes and sizes of ZnO nanostructures. A possible mechanism for the nanostructural change of the as-synthesized ZnO from particle to rod was elucidated based on the relative densities of H + and OH − in the solution.

  2. A Molecular Dynamics Study of the Epitaxial Growth of Metallic Nanoclusters Softly Deposited on Substrates with Very Different Lattice Parameter

    International Nuclear Information System (INIS)

    Jimenez-Saez, J C; Perez-MartIn, A M C; Jimenez-RodrIguez, J J

    2007-01-01

    The soft deposition of Cu and Au clusters on Au(001) and Cu(001) surfaces respectively is studied by constant-temperature molecular-dynamics simulations. The initial shape of the nanoclusters is icosahedral or truncated octahedral (Wulff type). Their number of atoms ranges between 12 and 1289 atoms. Bombardment energy is of the order of a few meV/atom. The atomic interactions are mimicked by a many-body potential based on the tightbinding model. The effect of the temperature as activation to get the complete epitaxy is analysed. We have found that Cu clusters manage to align their {002} planes with the substrate by increasing the temperature. However, there is not epitaxial growth in any case since the lattice becomes bcc or important stacking faults are generated. For Au clusters, the alignment of these planes is practically independent of the temperature

  3. Manipulating the kinetics of seeded growth for edge-selective metal deposition and the formation of concave au nanocrystals.

    Science.gov (United States)

    Laskar, Moitree; Zhong, Xiaolan; Li, Zhi-Yuan; Skrabalak, Sara E

    2013-10-01

    By manipulating the kinetics of seeded growth through judicious control of reaction conditions, edge-selective metal deposition can be achieved to synthesize new Au nanostructures with face-centered concavities, referred to herein as Au overgrown trisoctahedra. These nanostructures display higher sensitivity to changes in refractive index compared to both Au traditional trisoctahedra and the Au nanocube seeds from which they are grown. Often, concave nanostructures are achieved by selective etching processes or corner-selective overgrowth and adopt a stellated profile rather than a profile with face-centered concavities. The presented results illustrate another strategy toward concave nanostructures and can facilitate the synthesis of new concave nanostructures for applications in catalysis and chemical sensing. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. The application of magnetic self-filter to optimization of AIN film growth process during the impulse plasma deposition synthesis

    Directory of Open Access Journals (Sweden)

    Chodun Rafal

    2016-03-01

    Full Text Available This work presents the very first results of the application of plasma magnetic filtering achieved by a coil coupled with an electrical circuit of a coaxial accelerator during the synthesis of A1N thin films by use of Impulse Plasma Deposition method (IPD. The uniqueness of this technical solution lies in the fact that the filter is not supplied, controlled and synchronized from any external device. Our solution uses the energy from the electrical circuit of plasma accelerator. The plasma state was described on the basis of OES studies. Estimation of the effects of plasma filtering on the film quality was carried out on the basis of characterization of structure morphology (SEM, phase and chemical composition (vibrational spectroscopy. Our work has shown that the use of the developed magnetic self-filter improved the structure of the AlN coatings synthesized under the condition of impulse plasma, especially by the minimization of the tendency to deposit metallic aluminum droplets and columnar growth.

  5. Growth and characterization of polycrystalline Ge{sub 1-x}C{sub x} by reactive pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, M.P., E-mail: mayrap@fisica.uh.cu [Instituto de Ciencia y Tecnologia de Materiales, Zapata y G, P.O. Box 10400, Universidad de La Habana (Cuba); Farias, M.H.; Castillon, F.F.; Diaz, Jesus A.; Avalos, M. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Km 107 Carretera Tijuana-Ensenada, C.P. 22800 Ensenada, Baja California (Mexico); Ulloa, L. [Universidad de Guadalajara, (CUCEI) Blvd. Marcelino Garcia Barragan 1421, C.P. 44430 Guadalajara, Jalisco (Mexico); Gallegos, J.A.; Yee-Madeiros, H. [Escuela Superior de Fisica y Matematicas-IPN, UP' ALM' , Colonia Lindavista 07738 (Mexico)

    2011-03-15

    Polycrystalline thin films of Ge-C were grown on Si (1 1 1) substrates by means of reactive pulsed laser deposition with methane pressure of 100 mTorr. Effect substrate temperature, T{sub s}, on C incorporation to substitutional sites (x) in Ge{sub 1-x}C{sub x} was investigated systematically by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyzes. The substrate temperatures were ranging from 250 to 400 deg. C. The substitutional C composition x in the films by XRD were estimated using the Vegard's linear law. The maximum value of x calculated by XRD was 0.032 for T{sub s} of 350 deg. C. The position of the C 1s peak at 283.4 eV in the XPS spectrum confirmed the germanium-carbon alloys. XRD measurements indicated that x increased with T{sub s} from 250 deg. C to 350 deg. C. At T{sub s} = 400 deg. C, the estimation of x was lowered. However, the C content calculated by XPS analyzes increased with T{sub s} being more these values than substitutional C composition x. XPS and XRD analyzes demonstrate that the remaining C atoms are incorporated to interstitial sites. The use of the T{sub s} plays important roles in the incorporation of substitutional C and in restraining C-cluster formation in the reactive pulsed laser deposition growth of Ge-C/Si.

  6. 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

  7. 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

  8. The growth of axially modulated p–n GaN nanowires by plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Wu, Tung-Hsien; Hong, Franklin Chau-Nan

    2013-01-01

    Due to the n-type characteristics of intrinsic gallium nitride, p-type gallium nitride (GaN) is more difficult to synthesize than n-type gallium nitride in forming the p–n junctions for optoelectronic applications. For the growth of the p-type gallium nitride, magnesium is used as the dopant. The Mg-doped GaN nanowires (NWs) have been synthesized on (111)-oriented n + -silicon substrates by plasma-enhanced chemical vapor deposition. The scanning electron microscope images showed that the GaN NWs were bent at high Mg doping levels, and the transmission electron microscope characterization indicated that single-crystalline GaN NWs grew along < 0001 > orientation. As shown by energy dispersive spectroscopy, the Mg doping levels in GaN NWs increased with increasing partial pressure of magnesium nitride, which was employed as the dopant precursor for p-GaN NW growth. Photoluminescence measurements suggested the presence of both p- and n‐type GaN NWs. Furthermore, the GaN NWs with axial p–n junctions were aligned between either two-Ni or two-Al electrodes by applying alternating current voltages. The current–voltage characteristics have confirmed the formation of axial p–n junctions in GaN nanowires. - Highlights: ► Grow axially modulated GaN nanowires by plasma-enhanced chemical vapor deposition ► Control the Mg concentration of GaN nanowires by tuning Mg 3 N 2 temperature ► Align the GaN nanowires by applying alternating current voltages between electrodes

  9. In-situ atomic layer deposition growth of Hf-oxide

    International Nuclear Information System (INIS)

    Karavaev, Konstantin

    2010-01-01

    We have grown HfO 2 on Si(001) by atomic layer deposition (ALD) using HfCl 4 , TEMAHf, TDMAHf and H 2 O as precursors. The early stages of the ALD were investigated with high-resolution photoelectron spectroscopy and X-ray absorption spectroscopy. We observed the changes occurring in the Si 2p, O 1s, Hf 4f, Hf 4d, and Cl 2p (for HfCl 4 experiment) core level lines after each ALD cycle up to the complete formation of two layers of HfO 2 . The investigation was carried out in situ giving the possibility to determine the properties of the grown film after every ALD cycle or even after a half cycle. This work focused on the advantages in-situ approach in comparison with ex-situ experiments. The study provides to follow the evolution of the important properties of HfO 2 : contamination level, density and stoichiometry, and influence of the experimental parameters to the interface layer formation during ALD. Our investigation shows that in-situ XPS approach for ALD gives much more information than ex-situ experiments. (orig.)

  10. In-situ atomic layer deposition growth of Hf-oxide

    Energy Technology Data Exchange (ETDEWEB)

    Karavaev, Konstantin

    2010-06-17

    We have grown HfO{sub 2} on Si(001) by atomic layer deposition (ALD) using HfCl{sub 4}, TEMAHf, TDMAHf and H{sub 2}O as precursors. The early stages of the ALD were investigated with high-resolution photoelectron spectroscopy and X-ray absorption spectroscopy. We observed the changes occurring in the Si 2p, O 1s, Hf 4f, Hf 4d, and Cl 2p (for HfCl{sub 4} experiment) core level lines after each ALD cycle up to the complete formation of two layers of HfO{sub 2}. The investigation was carried out in situ giving the possibility to determine the properties of the grown film after every ALD cycle or even after a half cycle. This work focused on the advantages in-situ approach in comparison with ex-situ experiments. The study provides to follow the evolution of the important properties of HfO{sub 2}: contamination level, density and stoichiometry, and influence of the experimental parameters to the interface layer formation during ALD. Our investigation shows that in-situ XPS approach for ALD gives much more information than ex-situ experiments. (orig.)

  11. Water-assisted growth of graphene on carbon nanotubes by the chemical vapor deposition method.

    Science.gov (United States)

    Feng, Jian-Min; Dai, Ye-Jing

    2013-05-21

    Combining carbon nanotubes (CNTs) with graphene has been proved to be a feasible method for improving the performance of graphene for some practical applications. This paper reports a water-assisted route to grow graphene on CNTs from ferrocene and thiophene dissolved in ethanol by the chemical vapor deposition method in an argon flow. A double injection technique was used to separately inject ethanol solution and water for the preparation of graphene/CNTs. First, CNTs were prepared from ethanol solution and water. The injection of ethanol solution was suspended and water alone was injected into the reactor to etch the CNTs. Thereafter, ethanol solution was injected along with water, which is the key factor in obtaining graphene/CNTs. Transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Raman scattering analyses confirmed that the products were the hybrid materials of graphene/CNTs. X-ray photo-electron spectroscopy analysis showed the presence of oxygen rich functional groups on the surface of the graphene/CNTs. Given the activity of the graphene/CNT surface, CdS quantum dots adhered onto it uniformly through simple mechanical mixing.

  12. Growth of InN films on spinel substrates by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mitamura, K. [Institute of Industrial Science (IIS), The University of Tokyo, 4-6-1 Komaba, Megruro-ku, Tokyo 153-8505 (Japan); Ohta, J.; Fujioka, H. [Institute of Industrial Science (IIS), The University of Tokyo, 4-6-1 Komaba, Megruro-ku, Tokyo 153-8505 (Japan); Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kanagawa 213-0012 (Japan); Oshima, M. [Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2007-10-15

    We have grown InN films on MgAl{sub 2}O{sub 4}(111) substrates with atomically flat surfaces using pulsed laser deposition (PLD) and compared their structural properties with those grown on (Mn,Zn)Fe{sub 2}O{sub 4}(111) substrates. It has been revealed that InN(0001) films grow on MgAl{sub 2}O{sub 4}(111) with an in-plane epitaxial relationship of InN[1 anti 100]//MgAl{sub 2}O{sub 4}[1 anti 10], achieving a lattice mismatch minimum. The InN films exhibited a clear sixfold rotational symmetry, without 30 rotational domains and with a full width at half maximum value of the InN 0002 rocking curve being 17.5 arcmin. Comparison between InN films grown on MgAl{sub 2}O{sub 4} and those on (Mn,Zn)Fe{sub 2}O{sub 4} led us to conclude that suppression of the interfacial reactions between the InN films and the substrate is inherently important to obtain high quality InN on substrates with a spinel structure. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Epitaxial growth of ReS2(001) thin film via deposited-Re sulfurization

    Science.gov (United States)

    Urakami, Noriyuki; Okuda, Tetsuya; Hashimoto, Yoshio

    2018-02-01

    In this paper, we present the formation of large-size rhenium disulfide (ReS2) films via the sulfurization of Re films deposited on sapphire substrates. The effects of sulfurization temperature and pressure on the crystal quality were investigated. A [001]-oriented single crystal of ReS2 films with 6 × 10 mm2 area was realized. By sulfurizing Re films at 1100 °C, ReS2 films with well-defined sharp interfaces to c-plane sapphire substrates could be formed. Below and above the sulfurization temperature of 1100 °C, incomplete sulfurization and film degradation were observed. The twofold symmetry of the monocrystalline in-plane structure composed of Re-Re bonds along with Re-S bonds pointed to a distorted 1T structure, indicating that this structure is the most stable atomic arrangement for ReS2. For a S/Re compositional ratio equal to or slightly lower than 2.0, characteristic Raman vibrational modes with the narrowest line widths were observed. The typical absorption peak of ReS2 can be detected at 1.5 eV.

  14. Growth of Fe2O3 thin films by atomic layer deposition

    International Nuclear Information System (INIS)

    Lie, M.; Fjellvag, H.; Kjekshus, A.

    2005-01-01

    Thin films of α-Fe 2 O 3 (α-Al 2 O 3 -type crystal structure) and γ-Fe 2 O 3 (defect-spinel-type crystal structure) have been grown by the atomic layer deposition (ALD) technique with Fe(thd) 3 (iron derivative of Hthd = 2,2,6,6-tetramethylheptane-3,5-dione) and ozone as precursors. It has been shown that an ALD window exists between 160 and 210 deg. C. The films have been characterized by various techniques and are shown to comprise (001)-oriented columns of α-Fe 2 O 3 with no in-plane orientation when grown on soda-lime-glass and Si(100) substrates. Good quality films have been made with thicknesses ranging from 10 to 130 nm. Films grown on α-Al 2 O 3 (001) and MgO(100) substrates have the α-Fe 2 O 3 and γ-Fe 2 O 3 crystal structure, respectively, and consist of highly oriented columns with in-plane orientations matching those of the substrates

  15. Collagen and mineral deposition in rabbit cortical bone during maturation and growth: effects on tissue properties.

    Science.gov (United States)

    Isaksson, Hanna; Harjula, Terhi; Koistinen, Arto; Iivarinen, Jarkko; Seppänen, Kari; Arokoski, Jari P A; Brama, Pieter A; Jurvelin, Jukka S; Helminen, Heikki J

    2010-12-01

    We characterized the composition and mechanical properties of cortical bone during maturation and growth and in adult life in the rabbit. We hypothesized that the collagen network develops earlier than the mineralized matrix. Growth was monitored, and the rabbits were euthanized at birth (newborn), and at 1, 3, 6, 9, and 18 months of age. The collagen network was assessed biochemically (collagen content, enzymatic and non-enzymatic cross-links) in specimens from the mid-diaphysis of the tibia and femur and biomechanically (tensile testing) from decalcified whole tibia specimens. The mineralized matrix was analyzed using pQCT and 3-point bend tests from intact femur specimens. The collagen content and the Young's modulus of the collagen matrix increased significantly until the rabbits were 3 months old, and thereafter remained stable. The amount of HP and LP collagen cross-links increased continuously from newborn to 18 months of age, whereas PEN cross-links increased after 6 months of age. Bone mineral density and the Young's modulus of the mineralized bone increased until the rabbits were at least 6 months old. We concluded that substantial changes take place during the normal process of development in both the biochemical and biomechanical properties of rabbit cortical bone. In cortical bone, the collagen network reaches its mature composition and mechanical strength prior to the mineralized matrix. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  16. Porcine Is a Positional Candidate Gene Associated with Growth and Fat Deposition

    Directory of Open Access Journals (Sweden)

    Bong Hwan Choi

    2012-12-01

    Full Text Available Crosses between Korean and Landrace pigs have revealed a large quantitative trait loci (QTL region for fat deposition in a region (89 cM of porcine chromosome 4 (SSC4. To more finely map this QTL region and identify candidate genes for this trait, comparative mapping of pig and human chromosomes was performed in the present study. A region in the human genome that corresponds to the porcine QTL region was identified in HSA1q21. Furthermore, the LMNA gene, which is tightly associated with fat augmentation in humans, was localized to this region. Radiation hybrid (RH mapping using a Sus scrofa RH panel localized LMNA to a region of 90.3 cM in the porcine genome, distinct from microsatellite marker S0214 (87.3 cM. Two-point analysis showed that LMNA was linked to S0214, SW1996, and S0073 on SSC4 with logarithm (base 10 of odds scores of 20.98, 17.78, and 16.73, respectively. To clone the porcine LMNA gene and to delineate the genomic structure and sequences, including the 3′untranslated region (UTR, rapid amplification of cDNA ends was performed. The coding sequence of porcine LMNA consisted of 1,719 bp, flanked by a 5’UTR and a 3’UTR. Two synonymous single nucleotide polymorphisms (SNPs were identified in exons 3 and 7. Association tests showed that the SNP located in exon 3 (A193A was significantly associated with weight at 30 wks (p<0.01 and crude fat content (p<0.05. This association suggests that SNPs located in LMNA could be used for marker-assisted selection in pigs.

  17. Nucleation and growth kinetics for intercalated islands during deposition on layered materials with isolated pointlike surface defects

    International Nuclear Information System (INIS)

    Han, Yong; Lii-Rosales, A.; Zhou, Y.; Wang, C.-J.

    2017-01-01

    Theory and stochastic lattice-gas modeling is developed for the formation of intercalated metal islands in the gallery between the top layer and the underlying layer at the surface of layered materials. Our model for this process involves deposition of atoms, some fraction of which then enter the gallery through well-separated pointlike defects in the top layer. Subsequently, these atoms diffuse within the subsurface gallery leading to nucleation and growth of intercalated islands nearby the defect point source. For the case of a single point defect, continuum diffusion equation analysis provides insight into the nucleation kinetics. However, complementary tailored lattice-gas modeling produces a more comprehensive and quantitative characterization. We analyze the large spread in nucleation times and positions relative to the defect for the first nucleated island. We also consider the formation of subsequent islands and the evolution of island growth shapes. The shapes reflect in part our natural adoption of a hexagonal close-packed island structure. As a result, motivation and support for the model is provided by scanning tunneling microscopy observations of the formation of intercalated metal islands in highly-ordered pyrolytic graphite at higher temperatures.

  18. Improved growth of solution-deposited thin films on polycrystalline Cu(In,Ga)Se{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Witte, Wolfram; Hariskos, Dimitrios [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), 70565, Stuttgart (Germany); Abou-Ras, Daniel [Helmholtz-Zentrum Berlin fuer Materialien und Energie, 14109, Berlin (Germany)

    2016-04-15

    CdS and Zn(O,S) grown by chemical bath deposition (CBD) are well established buffer materials for Cu(In,Ga)Se{sub 2} (CIGS) solar cells. As recently reported, a non-contiguous coverage of CBD buffers on CIGS grains with {112} surfaces can be detected, which was explained in terms of low surface energies of the {112} facets, leading to deteriorated wetting of the chemical solution on the CIGS surface. In the present contribution, we report on the effect of air annealing of CIGS thin films prior to the CBD of CdS and Zn(O,S) layers. In contrast to the growth on the as-grown CIGS layers, these buffer lay- ers grow densely on the annealed CIGS layer, even on grains with {112} surfaces. We explain the different growth behavior by increased surface energies of CIGS grains due to the annealing step, i.e., due to oxidation of the CIGS surface. Reference solar cells were processed and completed by i-ZnO/ZnO:Al layers for CdS and by (Zn,Mg)O/ZnO:Al for Zn(O,S) buffers. For solar cells with both, CdS and Zn(O,S) buffers, air-annealed CIGS films with improved buffer coverage resulted in higher power-conversion efficiencies, as compared with the devices containing as-grown CIGS layers. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. 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.

  20. Direct growth of Ge quantum dots on a graphene/SiO2/Si structure using ion beam sputtering deposition.

    Science.gov (United States)

    Zhang, Z; Wang, R F; Zhang, J; Li, H S; Zhang, J; Qiu, F; Yang, J; Wang, C; Yang, Y

    2016-07-29

    The growth of Ge quantum dots (QDs) using the ion beam sputtering deposition technique has been successfully conducted directly on single-layer graphene supported by SiO2/Si substrate. The results show that the morphology and size of Ge QDs on graphene can be modulated by tuning the Ge coverage. Charge transfer behavior, i.e. doping effect in graphene has been demonstrated at the interface of Ge/graphene. Compared with that of traditional Ge dots grown on Si substrate, the positions of both corresponding photoluminescence (PL) peaks of Ge QDs/graphene hybrid structure undergo a large red-shift, which can probably be attributed to the lack of atomic intermixing and the existence of surface states in this hybrid material. According to first-principles calculations, the Ge growth on the graphene should follow the so-called Volmer-Weber mode instead of the Stranski-Krastanow one which is observed generally in the traditional Ge QDs/Si system. The calculations also suggest that the interaction between Ge and graphene layer can be enhanced with the decrease of the Ge coverage. Our results may supply a prototype for fabricating novel optoelectronic devices based on a QDs/graphene hybrid nanostructure.

  1. 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.

  2. A simple model for quantifying the degree of layer-by-layer growth in low energy ion deposition of thin films

    International Nuclear Information System (INIS)

    Huhtamaeki, T.; Jahma, M.O.; Koponen, I.T.

    2007-01-01

    Layer-by-layer growth of thin films can be promoted by using low energy ion deposition (LEID) techniques. The basic process affecting the growth are often quite diverse, but often the ion impact induced inter layer mass transfer processes due to adatom insertion to lower step edges or pile-ups to step edges above dominate. In this paper we propose a simple phenomenological model which describes the growth of thin films in LEID under these conditions. The model makes possible to distinguish the dominant growth, the detection of the transition from the 3D growth to 2D growth, and it can be used to quantify the degree of layer-by-layer growth. The model contains only two parameters, which can be phenomenologically related to the properties of the bombarding ion beam

  3. 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.

  4. 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.

  5. 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

  6. Vertical Growth of Superconducting Crystalline Hollow Nanowires by He+ Focused Ion Beam Induced Deposition.

    Science.gov (United States)

    Córdoba, Rosa; Ibarra, Alfonso; Mailly, Dominique; De Teresa, José Ma

    2018-02-14

    Novel physical properties appear when the size of a superconductor is reduced to the nanoscale, in the range of its superconducting coherence length (ξ 0 ). Such nanosuperconductors are being investigated for potential applications in nanoelectronics and quantum computing. The design of three-dimensional nanosuperconductors allows one to conceive novel schemes for such applications. Here, we report for the first time the use of a He + focused-ion-beam-microscope in combination with the W(CO) 6 precursor to grow three-dimensional superconducting hollow nanowires as small as 32 nm in diameter and with an aspect ratio (length/diameter) of as much as 200. Such extreme resolution is achieved by using a small He + beam spot of 1 nm for the growth of the nanowires. As shown by transmission electron microscopy, they display grains of large size fitting with face-centered cubic WC 1-x phase. The nanowires, which are grown vertically to the substrate, are felled on the substrate by means of a nanomanipulator for their electrical characterization. They become superconducting at 6.4 K and show large critical magnetic field and critical current density resulting from their quasi-one-dimensional superconducting character. These results pave the way for future nanoelectronic devices based on three-dimensional nanosuperconductors.

  7. 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....

  8. The growth of nanostructured Cu{sub 2}ZnSnS{sub 4} films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Che Sulaiman, Nurul Suhada; Nee, Chen Hon [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Ling [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Lee, Yen Sian [UM Power Energy Dedicated Advanced Centre (UMPEDAC), University of Malaya, 50603 Kuala Lumpur (Malaysia); Tou, Teck Yong [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Shan, E-mail: seongshan@gmail.com [UM Power Energy Dedicated Advanced Centre (UMPEDAC), University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-11-01

    Highlights: • Nanostructured CZTS films were grown at room temperature by using 355 nm laser. • CZTS films with E{sub g} of 1.9 eV have been obtained at 2 J cm{sup −2} at room temperature. • At high fluence, Cu/Sn rich droplets affected the overall quality of the films. • Improved crystallinity and E{sub g} of 1.5 eV was obtained at substrate temperature as low as 100 °C. - Abstract: In this work, we investigated on the growth of Cu{sub 2}ZnSnS{sub 4} films by using pulsed Nd:YAG laser (355 nm) ablation of a quaternary Cu{sub 2}ZnSnS{sub 4} target. Depositions were performed at laser fluence from 0.5 to 4 J cm{sup −2}. The films were grown at substrate temperature from 27 °C to 300 °C onto glass and silicon substrates. The dependence of the film morphology, composition, and optical properties are studied and discussed with respect to laser fluence and substrate temperature. Composition analysis from energy dispersive X-ray spectral results show that CZTS films with composition near stoichiometric were obtained at an optimized fluence at 2 J cm{sup −2} by 355 nm laser where the absorption coefficient is >10{sup 4} cm{sup −1}, and optical band gap from a Tauc plot was ∼1.9 eV. At high fluence, Cu and Sn rich droplets were detected which affect the overall quality of the films. The presence of the droplets was associated to the high degree of preferential and subsurface melting on the target during high fluence laser ablation. Crystallinity and optical band gap (1.5 eV) were improved when deposition was performed at substrate temperature of 100 °C.

  9. Structural and photoluminescence investigation on the hot-wire assisted plasma enhanced chemical vapor deposition growth silicon nanowires

    International Nuclear Information System (INIS)

    Chong, Su Kong; Goh, Boon Tong; Wong, Yuen-Yee; Nguyen, Hong-Quan; Do, Hien; Ahmad, Ishaq; Aspanut, Zarina; Muhamad, Muhamad Rasat; Dee, Chang Fu; Rahman, Saadah Abdul

    2012-01-01

    High density of silicon nanowires (SiNWs) were synthesized by a hot-wire assisted plasma enhanced chemical vapor deposition technique. The structural and optical properties of the as-grown SiNWs prepared at different rf power of 40 and 80 W were analyzed in this study. The SiNWs prepared at rf power of 40 W exhibited highly crystalline structure with a high crystal volume fraction, X C of ∼82% and are surrounded by a thin layer of SiO x . The NWs show high absorption in the high energy region (E>1.8 eV) and strong photoluminescence at 1.73 to 2.05 eV (red–orange region) with a weak shoulder at 1.65 to 1.73 eV (near IR region). An increase in rf power to 80 W reduced the X C to ∼65% and led to the formation of nanocrystalline Si structures with a crystallite size of <4 nm within the SiNWs. These NWs are covered by a mixture of uncatalyzed amorphous Si layer. The SiNWs prepared at 80 W exhibited a high optical absorption ability above 99% in the broadband range between 220 and ∼1500 nm and red emission between 1.65 and 1.95 eV. The interesting light absorption and photoluminescence properties from both SiNWs are discussed in the text. - Highlights: ► Growth of random oriented silicon nanowires using hot-wire assisted plasma enhanced chemical vapor deposition. ► Increase in rf power reduces the crystallinity of silicon nanowires. ► High density and nanocrystalline structure in silicon nanowires significant enhance the near IR light absorption. ► Oxide defects and silicon nanocrystallites in silicon nanowires reveal photoluminescence in red–orange and red regions.

  10. Impact of permethrin-treated bed nets on malaria, anemia, and growth in infants in an area of intense perennial malaria transmission in western Kenya

    NARCIS (Netherlands)

    ter Kuile, Feiko O.; Terlouw, Dianne J.; Kariuki, Simon K.; Phillips-Howard, Penelope A.; Mirel, Lisa B.; Hawley, William A.; Friedman, Jennifer F.; Shi, Ya Ping; Kolczak, Margarette S.; Lal, Altaf A.; Vulule, John M.; Nahlen, Bernard L.

    2003-01-01

    As part of a community-based, group-randomized, controlled trial of insecticide-treated bed nets (ITNs) in an area with intense malaria transmission in western Kenya, a birth cohort (n = 833) was followed monthly until the age of 24 months to determine the potential beneficial and adverse effects of

  11. The NordiNet® International Outcome Study and NovoNet® ANSWER Program®: rationale, design, and methodology of two international pharmacoepidemiological registry-based studies monitoring long-term clinical and safety outcomes of growth hormone therapy (Norditropin®).

    Science.gov (United States)

    Höybye, Charlotte; Sävendahl, Lars; Christesen, Henrik Thybo; Lee, Peter; Pedersen, Birgitte Tønnes; Schlumpf, Michael; Germak, John; Ross, Judith

    2013-01-01

    Randomized controlled trials have shown that growth hormone (GH) therapy has effects on growth, metabolism, and body composition. GH therapy is prescribed for children with growth failure and adults with GH deficiency. Carefully conducted observational study of GH treatment affords the opportunity to assess long-term treatment outcomes and the clinical factors and variables affecting those outcomes, in patients receiving GH therapy in routine clinical practice. The NordiNet® International Outcome Study (IOS) and the American Norditropin® Web Enabled Research (ANSWER Program®) are two complementary, non-interventional, observational studies that adhere to current guidelines for pharmacoepidemiological data. The studies include pediatric and adult patients receiving Norditropin®, as prescribed by their physicians. The studies gather long-term data on the safety and effectiveness of reallife treatment with the recombinant human GH, Norditropin®. We describe the origins, aims, objectives, and design methodology of the studies, as well as their governance and validity, strengths, and limitations. The NordiNet® IOS and ANSWER Program® studies will provide valid insights into the effectiveness and safety of GH treatment across a diverse and large patient population treated in accordance with real-world clinical practice and following the Good Pharmacoepidemiological Practice and STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) guidelines.

  12. Undoped and in-situ B doped GeSn epitaxial growth on Ge by atmospheric pressure-chemical vapor deposition

    DEFF Research Database (Denmark)

    Vincent, B.; Gencarelli, F.; Bender, H.

    2011-01-01

    In this letter, we propose an atmospheric pressure-chemical vapor deposition technique to grow metastable GeSn epitaxial layers on Ge. We report the growth of defect free fully strained undoped and in-situ B doped GeSn layers on Ge substrates with Sit contents up to 8%. Those metastable layers stay...

  13. Microwave plasma enhanced chemical vapor deposition growth of few-walled carbon nanotubes using catalyst derived from an iron-containing block copolymer precursor

    International Nuclear Information System (INIS)

    Wang Peng; Lu, Jennifer; Zhou, Otto

    2008-01-01

    The microwave plasma enhanced chemical vapor deposition (MPECVD) method is now commonly used for directional and conformal growth of carbon nanotubes (CNTs) on supporting substrates. One of the shortcomings of the current process is the lack of control of the diameter and diameter distribution of the CNTs due to difficulties in synthesizing well-dispersed catalysts. Recently, block copolymer derived catalysts have been developed which offer the potential of fine control of both the size of and the spacing between the metal clusters. In this paper we report the successful growth of CNTs with narrow diameter distribution using polystyrene-block-polyferrocenylethylmethylsilane (PS-b-PFEMS) as the catalyst precursor. The study shows that higher growth pressure leads to better CNT growth. Besides the pressure, the effects on the growth of CNTs of the growth parameters, such as temperature and precursor gas ratio, are also studied

  14. Comparison between radical- and energetic ion-induced growth of SiCxNy films in plasma immersion ion implantation and deposition

    International Nuclear Information System (INIS)

    Afanasyev-Charkin, I.V.; Nastasi, M.

    2004-01-01

    Ternary SiC x N y compounds are materials with some remarkable properties such as high oxidation resistance and high hardness. In this work we compare the properties of SiC x N y films obtained using radio-frequency (rf) and pulsed glow discharge (PGD) plasmas with combinations of SiH 4 , C 2 H 2 , N 2 , and Ar source gases. The pulsed voltage used for the rf deposition was 200 V and for the PGD deposition it was 4 kV. During the rf growth, the growth takes place mostly by attaching neutral radicals to form chemical bonds. In the PGD method, the deposition takes place by subplantation and surface activation by energetic ions. We show that in the case of low-energy RF deposition, a high relative number of C-N bonds with sp 3 hybridization is formed and very few Si-C bonds can be observed. Apparently the growth of carbon nitride and silicon nitride networks takes place independently. This indicates that SiH 3 radicals attach to the dangling bonds of silicon and nitrogen, whereas C 2 H radicals attach to the dangling bonds of carbon and nitrogen. During pulsed glow discharge deposition, bonds between all three components are formed apparently by means of subplantation and damage-induced disorder. The hardness of the PGD films exceed that of the RF films, showing that to form a dense SiC x N y film one has to either supply energy during the growth of the films by heating the substrate, as in the case of chemical vapor deposition or by using energetic ions

  15. Epitaxial growth of Si1−xGex alloys and Ge on Si(100) by electron-cyclotron-resonance Ar plasma chemical vapor deposition without substrate heating

    International Nuclear Information System (INIS)

    Ueno, Naofumi; Sakuraba, Masao; Murota, Junichi; Sato, Shigeo

    2014-01-01

    By using electron-cyclotron-resonance (ECR) Ar-plasma chemical vapor deposition (CVD) without substrate heating, the epitaxial growth process of Si 1−x Ge x alloy and Ge films deposited directly on dilute-HF-treated Si(100) was investigated. From the reflection high energy electron diffraction patterns of the deposited Si 1−x Ge x alloy (x = 0.50, 0.75) and Ge films on Si(100), it is confirmed that epitaxial growth can be realized without substrate heating, and that crystallinity degradation at larger film thickness is observed. The X-ray diffraction peak of the epitaxial films reveals the existence of large compressive strain, which is induced by lattice matching with the Si(100) substrate at smaller film thicknesses, as well as strain relaxation behavior at larger film thicknesses. The Ge fraction of Si 1−x Ge x thin film is in good agreement with the normalized GeH 4 partial pressure. The Si 1−x Ge x deposition rate increases with an increase of GeH 4 partial pressure. The GeH 4 partial pressure dependence of partial deposition rates [(Si or Ge fraction) × (Si 1−x Ge x thickness) / (deposition time)] shows that the Si partial deposition rate is slightly enhanced by the existence of Ge. From these results, it is proposed that the ECR-plasma CVD process can be utilized for Ge fraction control in highly-strained heterostructure formation of group IV semiconductors. - Highlights: • Si 1−x Ge x alloy and Ge were epitaxially grown on Si(100) without substrate heating. • Large strain and its relaxation behavior can be observed by X-ray diffraction. • Ge fraction of Si 1−x Ge x is equal to normalized GeH 4 partial pressure. • Si partial deposition rate is slightly enhanced by existence of Ge

  16. Morphology and kinetics of crystals growth in amorphous films of Cr2O3, deposited by laser ablation

    Science.gov (United States)

    Bagmut, Aleksandr

    2018-06-01

    An electron microscopic investigation was performed on the structure and kinetics of the crystallization of amorphous Cr2O3 films, deposited by pulsed laser sputtering of chromium target in an oxygen atmosphere. The crystallization was initiated by the action of an electron beam on an amorphous film in the column of a transmission electron microscope. The kinetic curves were plotted on the basis of a frame-by-frame analysis of the video recorded during the crystallization of the film. It was found that the amorphous phase - crystal phase transition in Cr2O3 films occurs as a layer polymorphic crystallization and is characterized by the values of the dimensionless relative length unit δ0 ≈ 2000-3100. The action of the electron beam initiates the formation of crystals of two basic morphological forms: disk-shaped and sickle-shaped. Growth of a disk-shaped crystals is characterized by a constant rate v and the quadratic dependence of the fraction of the crystalline phase x on the time t. Sickle-shaped crystal at an initial stage, as it grows, becomes as ring-shaped and disk-shaped crystal. The growth of a sickle-shaped crystal is characterized by normal and tangential velocity components, which depend on the time as ∼√t and as ∼1/√t respectively The end point of the arc at the interface between the amorphous and crystalline phases as the crystal grows describes a curve, which is similar to the Fermat helix. For sickle-shaped, as well as for disk-shaped crystals, the degree of crystallinity x ∼ t2.

  17. Improvement of InN layers deposited on Si(111) by RF sputtering using a low-growth-rate InN buffer layer

    International Nuclear Information System (INIS)

    Valdueza-Felip, S.; Ibáñez, J.; Monroy, E.; González-Herráez, M.; Artús, L.; Naranjo, F.B.

    2012-01-01

    We investigate the influence of a low-growth-rate InN buffer layer on structural and optical properties of wurtzite nanocrystalline InN films deposited on Si(111) substrates by reactive radio-frequency sputtering. The deposition conditions of the InN buffer layer were optimized in terms of morphological and structural quality, leading to films with surface root-mean-square roughness of ∼ 1 nm under low-growth-rate conditions (60 nm/h). The use of the developed InN buffer layer improves the crystalline quality of the subsequent InN thick films deposited at high growth rate (180 nm/h), as confirmed by the narrowing of X-ray diffraction peaks and the increase of the average grain size of the layers. This improvement of the structural quality is further confirmed by Raman scattering spectroscopy measurements. Room temperature PL emission peaking at ∼ 1.58 eV is observed for InN samples grown with the developed buffer layer. The crystal and optical quality obtained for InN films grown on Si(111) using the low-growth-rate InN buffer layer become comparable to high-quality InN films deposited directly on GaN templates by RF sputtering. - Highlights: ► Improved RF-sputtered InN films on Si(111) using a low-growth-rate InN buffer layer. ► Enhanced structural quality confirmed by X-ray diffraction and Raman measurements. ► Room-temperature photoluminescence emission at 1.58 eV. ► InN films deposited with buffer layer on Si comparable to InN LAYERS on GaN templates.

  18. Improvement of InN layers deposited on Si(111) by RF sputtering using a low-growth-rate InN buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Valdueza-Felip, S., E-mail: sirona.valdueza@depeca.uah.es [Electronics Dept., Polytechnic School, University of Alcala, Madrid-Barcelona Road, km 33.6, 28871 Alcala de Henares, Madrid (Spain); Ibanez, J. [Institut de Ciencies de la Terra Jaume Almera, Consejo Superior de Investigaciones Cientificas (CSIC), c/Lluis Sole Sabaris s/n, 08028 Barcelona (Spain); Monroy, E. [CEA-Grenoble, INAC/SP2M/NPSC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Gonzalez-Herraez, M. [Electronics Dept., Polytechnic School, University of Alcala, Madrid-Barcelona Road, km 33.6, 28871 Alcala de Henares, Madrid (Spain); Artus, L. [Institut de Ciencies de la Terra Jaume Almera, Consejo Superior de Investigaciones Cientificas (CSIC), c/Lluis Sole Sabaris s/n, 08028 Barcelona (Spain); Naranjo, F.B. [Electronics Dept., Polytechnic School, University of Alcala, Madrid-Barcelona Road, km 33.6, 28871 Alcala de Henares, Madrid (Spain)

    2012-01-31

    We investigate the influence of a low-growth-rate InN buffer layer on structural and optical properties of wurtzite nanocrystalline InN films deposited on Si(111) substrates by reactive radio-frequency sputtering. The deposition conditions of the InN buffer layer were optimized in terms of morphological and structural quality, leading to films with surface root-mean-square roughness of {approx} 1 nm under low-growth-rate conditions (60 nm/h). The use of the developed InN buffer layer improves the crystalline quality of the subsequent InN thick films deposited at high growth rate (180 nm/h), as confirmed by the narrowing of X-ray diffraction peaks and the increase of the average grain size of the layers. This improvement of the structural quality is further confirmed by Raman scattering spectroscopy measurements. Room temperature PL emission peaking at {approx} 1.58 eV is observed for InN samples grown with the developed buffer layer. The crystal and optical quality obtained for InN films grown on Si(111) using the low-growth-rate InN buffer layer become comparable to high-quality InN films deposited directly on GaN templates by RF sputtering. - Highlights: Black-Right-Pointing-Pointer Improved RF-sputtered InN films on Si(111) using a low-growth-rate InN buffer layer. Black-Right-Pointing-Pointer Enhanced structural quality confirmed by X-ray diffraction and Raman measurements. Black-Right-Pointing-Pointer Room-temperature photoluminescence emission at 1.58 eV. Black-Right-Pointing-Pointer InN films deposited with buffer layer on Si comparable to InN LAYERS on GaN templates.

  19. The Apical Actin Fringe Contributes to Localized Cell Wall Deposition and Polarized Growth in the Lily Pollen Tube1[W][OPEN

    Science.gov (United States)

    Rounds, Caleb M.; Hepler, Peter K.; Winship, Lawrence J.

    2014-01-01

    In lily (Lilium formosanum) pollen tubes, pectin, a major component of the cell wall, is delivered through regulated exocytosis. The targeted transport and secretion of the pectin-containing vesicles may be controlled by the cortical actin fringe at the pollen tube apex. Here, we address the role of the actin fringe using three different inhibitors of growth: brefeldin A, latrunculin B, and potassium cyanide. Brefeldin A blocks membrane trafficking and inhibits exocytosis in pollen tubes; it also leads to the degradation of the actin fringe and the formation of an aggregate of filamentous actin at the base of the clear zone. Latrunculin B, which depolymerizes filamentous actin, markedly slows growth but allows focused pectin deposition to continue. Of note, the locus of deposition shifts frequently and correlates with changes in the direction of growth. Finally, potassium cyanide, an electron transport chain inhibitor, briefly stops growth while causing the actin fringe to completely disappear. Pectin deposition continues but lacks focus, instead being delivered in a wide arc across the pollen tube tip. These data support a model in which the actin fringe contributes to the focused secretion of pectin to the apical cell wall and, thus, to the polarized growth of the pollen tube. PMID:25037212

  20. Controlled growth of carbon nanofibers using plasma enhanced chemical vapor deposition: Effect of catalyst thickness and gas ratio

    International Nuclear Information System (INIS)

    Saidin, M.A.R.; Ismail, A.F.; Sanip, S.M.; Goh, P.S.; Aziz, M.; Tanemura, M.

    2012-01-01

    The characteristics of carbon nanofibers (CNFs) grown, using direct current plasma enhanced chemical vapor deposition system reactor under various acetylene to ammonia gas ratios and different catalyst thicknesses were studied. Nickel/Chromium-glass (Ni/Cr-glass) thin film catalyst was employed for the growth of CNF. The grown CNFs were then characterized using Raman spectroscopy, field emission scanning electron microscopy and transmission electron microscopy (TEM). Raman spectroscopy showed that the Ni/Cr-glass with thickness of 15 nm and gas ratio acetylene to ammonia of 1:3 produced CNFs with the lowest I D /I G value (the relative intensity of D-band to G-band). This indicated that this catalyst thickness and gas ratio value is the optimum combination for the synthesis of CNFs under the conditions studied. TEM observation pointed out that the CNFs produced have 104 concentric walls and the residual catalyst particles were located inside the tubes of CNFs. It was also observed that structural morphology of the grown CNFs was influenced by acetylene to ammonia gas ratio and catalyst thickness.

  1. Controlled growth of carbon nanofibers using plasma enhanced chemical vapor deposition: Effect of catalyst thickness and gas ratio

    Energy Technology Data Exchange (ETDEWEB)

    Saidin, M.A.R. [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Ismail, A.F., E-mail: afauzi@utm.my [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Sanip, S.M.; Goh, P.S.; Aziz, M. [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Tanemura, M. [Department of Frontier Material, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2012-01-31

    The characteristics of carbon nanofibers (CNFs) grown, using direct current plasma enhanced chemical vapor deposition system reactor under various acetylene to ammonia gas ratios and different catalyst thicknesses were studied. Nickel/Chromium-glass (Ni/Cr-glass) thin film catalyst was employed for the growth of CNF. The grown CNFs were then characterized using Raman spectroscopy, field emission scanning electron microscopy and transmission electron microscopy (TEM). Raman spectroscopy showed that the Ni/Cr-glass with thickness of 15 nm and gas ratio acetylene to ammonia of 1:3 produced CNFs with the lowest I{sub D}/I{sub G} value (the relative intensity of D-band to G-band). This indicated that this catalyst thickness and gas ratio value is the optimum combination for the synthesis of CNFs under the conditions studied. TEM observation pointed out that the CNFs produced have 104 concentric walls and the residual catalyst particles were located inside the tubes of CNFs. It was also observed that structural morphology of the grown CNFs was influenced by acetylene to ammonia gas ratio and catalyst thickness.

  2. Growth, structure, and tribological behavior of atomic layer-deposited tungsten disulphide solid lubricant coatings with applications to MEMS

    International Nuclear Information System (INIS)

    Scharf, T.W.; Prasad, S.V.; Dugger, M.T.; Kotula, P.G.; Goeke, R.S.; Grubbs, R.K.

    2006-01-01

    This paper describes the synthesis, structure, and tribological behavior of nanocomposite tungsten disulphide (WS 2 ) solid lubricant films grown by atomic layer deposition. A new catalytic route, incorporating a diethyl zinc catalyst, was established to promote the adsorption and growth of WS 2 . The films were grown down to 8 nm in thickness by sequential exposures of WF 6 and H 2 S gases in a viscous flow reactor on Si, SiO 2 , stainless steel, and polycrystalline Si and electroplated Ni microelectromechanical systems structures. Films were studied by cross-sectional transmission electron microscopy (XTEM) with Automated eXpert Spectral Image Analysis (AXSIA) software for X-ray spectral images and X-ray diffraction to determine the coating conformality and crystallinity. The coatings exhibited a hexagonal layered structure with predominant preferentially orientated (0 0 2) basal planes. Regardless of orientation to the substrate surface, these basal planes when sheared imparted low friction with a steady-state friction coefficient as low as 0.008 to 50,000 cycles in a dry nitrogen environment. The formation of smooth transfer films during wear provided low interfacial shear stresses during sliding thus achieving low friction and wear. The XTEM combined with AXSIA of the wear tracks identified this mechanism and the effects of vapor phase reaction by-product etching on insulating and native polycrystalline Si and Ni surfaces

  3. Growth of α-V{sub 2}O{sub 5} nanostructured thin films as a function of deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Megha, E-mail: meghasingh.life@gmail.com; Sharma, Rabindar K.; Reddy, G. B. [Thin film Laboratory, Department of Physics, Indian Institute of Technology Delhi -110016 (India)

    2016-05-23

    In this communication, we synthesizedvanadium pentoxide (α-V{sub 2}O{sub 5}) nanostructured thin films (NSTs) using four different methods for obtaining vanadate species namely thermal evaporation (source of vanadate species are V{sub 2}O{sub 5} powder and vanadium metal foil) and plasma assisted sublimation process (source of vanadate species are V{sub 2}O{sub 5} powder and vanadium metal foil). The effect of plasmaon morphological and structural propertieshave been systematicallystudied. XRD revealed thermal evaporation process yielded amorphous films whereassublimation process yielded highly crystalline α-V{sub 2}O{sub 5} films. HRTEM of nanobelts show, the growth is preferred in (001) crystallographic direction with interplanar distance of 0.43 nm. XPS revealed O/V ratio of ~2.4, which nearly agrees with standard V{sub 2}O{sub 5} stoichiometry. SEM revealed deposition process affect morphology of films; thermal evaporation results in smoother film while plasma assisted sublimation process reveals nanoflakes and nanobelts (NBs). All the results are inconcordance with each other.

  4. Growth of β-FeSi2 layers on Si (111) by solid phase and reactive deposition epitaxies

    International Nuclear Information System (INIS)

    Miquita, D.R.; Paniago, R.; Rodrigues, W.N.; Moreira, M.V.B.; Pfannes, H.-D.; Oliveira, A.G. de

    2005-01-01

    Iron silicides were grown on Si (111) substrates by Solid Phase Epitaxy (SPE) and Reactive Deposition Epitaxy (RDE) to identify the optimum conditions to obtain the semiconducting β-FeSi 2 phase. The films were produced under different growth and annealing conditions and analyzed in situ and ex situ by X-ray Photoelectron Spectroscopy, and ex situ by Conversion Electron Moessbauer Spectroscopy. The use of these techniques allowed the investigation of different depth regions of the grown layer. Films of the ε-FeSi and β-FeSi 2 phases were obtained as well as the mixtures Fe 3 Si + ε-FeSi and ε-FeSi + β-FeSi 2 . The sequence Fe 3 Si→ε-FeSi→β-FeSi 2 was found upon annealing, where the phase transformation occurred due to the migration of silicon atoms from the substrate to the surface region of the grown layer. The best conditions for the phase transformation in SPE samples were met after annealing in the range 700 - 800 deg. C. For the RDE samples, the transition to the beta phase occurred between 600 and 700 deg. C, but pure β-FeSi 2 was obtained only after two hours of annealing at 700 deg. C

  5. A Comparative Study of Three Different Chemical Vapor Deposition Techniques of Carbon Nanotube Growth on Diamond Films

    Directory of Open Access Journals (Sweden)

    Betty T. Quinton

    2013-01-01

    Full Text Available This paper compares between the methods of growing carbon nanotubes (CNTs on diamond substrates and evaluates the quality of the CNTs and the interfacial strength. One potential application for these materials is a heat sink/spreader for high-power electronic devices. The CNTs and diamond substrates have a significantly higher specific thermal conductivity than traditional heat sink/spreader materials making them good replacement candidates. Only limited research has been performed on these CNT/diamond structures and their suitability of different growth methods. This study investigates three potential chemical vapor deposition (CVD techniques for growing CNTs on diamond: thermal CVD (T-CVD, microwave plasma-enhanced CVD (MPE-CVD, and floating catalyst thermal CVD (FCT-CVD. Scanning electron microscopy (SEM and high-resolution transmission electron microscopy (TEM were used to analyze the morphology and topology of the CNTs. Raman spectroscopy was used to assess the quality of the CNTs by determining the ID/IG peak intensity ratios. Additionally, the CNT/diamond samples were sonicated for qualitative comparisons of the durability of the CNT forests. T-CVD provided the largest diameter tubes, with catalysts residing mainly at the CNT/diamond interface. The MPE-CVD process yielded non uniform defective CNTs, and FCT-CVD resulted in the smallest diameter CNTs with catalyst particles imbedded throughout the length of the nanotubes.

  6. Growth and characterization of ternary Ni, Mg–Al and Ni–Al layered double hydroxides thin films deposited by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Birjega, R. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele, 76900 Bucharest (Romania); Vlad, A., E-mail: angela.vlad@gmail.com [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele, 76900 Bucharest (Romania); Matei, A.; Ion, V.; Luculescu, C.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele, 76900 Bucharest (Romania); Zavoianu, R. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest (Romania)

    2016-09-01

    Layered double hydroxides (LDHs) are a class of layered materials consisting of positively charged brucite-like layers and exchangeable interlayer anions. Layered double hydroxides containing a transition metal which undergoes a reversible redox reaction in the useful potential range have been proposed as electrode coating materials due to their properties of charge transport and redox catalysts in basic solutions. Ni–Al,(Ni,Mg)–Al and, as reference, non-electronically conductive Mg–Al double hydroxides thin films were obtained via pulsed laser deposition technique. The thin films were deposited on different substrates (Si, glass) by using a Nd:YAG laser (1064 nm) working at a repetition rate of 10 Hz. X-ray diffraction, Atomic Force Microscopy, Energy Dispersive X-ray spectroscopy, Fourier Transform Infra-Red Spectroscopy, Secondary Ions Mass Spectrometry, Impedance Analyzer and ellipsometry were the techniques used for the as deposited thin films investigation. The optical properties of Ni based LDH thin films and the effect of the Ni amount on the structural, morphological and optical response are evidenced. The optical band gap values, covering a domain between 3.84 eV and 4.38 eV, respond to the Ni overall concentration: the higher Ni amount the lower the band gap value. - Highlights: • Ternary Ni, Mg–Al and Ni–Al layered double hydroxides thin films were deposited. • The effect of the nickel is evidenced. • The possibility to tailor the materials accompanied by an optical response is shown.

  7. Growth and microstructure of columnar Y-doped SrZrO{sub 3} films deposited on Pt-coated MgO by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Sijun, E-mail: sluo1@tulane.edu; Riggs, Brian C.; Shipman, Joshua T.; Adireddy, Shiva; Sklare, Samuel C.; Chrisey, Douglas B., E-mail: dchrisey@tulane.edu [Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118 (United States); Zhang, Xiaodong; Koplitz, Brent [Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States)

    2015-07-21

    Direct integration of proton conductor films on Pt-coated substrates opens the way to film-based proton transport devices. Columnar SrZr{sub 0.95}Y{sub 0.05}O{sub 3−δ} (SZY) films with dense microstructure were deposited on Pt-coated MgO(100) substrates at 830 °C by pulsed laser deposition. The optimal window of ambient O{sub 2} pressure for good crystallinity of SZY films is from 400 to 600 mTorr. The ambient O{sub 2} compresses the plasma plume of SZY and increases the deposition rate. The 10 nm thick Ti adhesion layer on MgO(100) greatly affects the orientation of the sputtered Pt layers. Pt deposited directly on MgO shows a highly (111)-preferred orientation and leads to preferentially oriented SZY films while the addition of a Ti adhesion layer makes Pt show a less preferential orientation that leads to randomly oriented SZY films. The RMS surface roughness of preferentially oriented SZY films is larger than that of randomly oriented SZY films deposited under the same ambient O{sub 2} pressure. As the O{sub 2} pressure increased, the RMS surface roughness of preferentially oriented SZY films increased, reaching 45.7 nm (2.61% of film thickness) at 600 mTorr. This study revealed the ambient O{sub 2} pressure and orientation dependent surface roughness of SZY films grown on Pt-coated MgO substrates, which provides the potential to control the surface microstructure of SZY films for electrochemical applications in film-based hydrogen devices.

  8. Size- and density-controlled deposition of Ag nanoparticle films by a novel low-temperature spray chemical vapour deposition method—research into mechanism, particle growth and optical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: yang.liu@helmholtz-berlin.de; Plate, Paul, E-mail: paul.plate@helmholtz-berlin.de; Hinrichs, Volker; Köhler, Tristan; Song, Min; Manley, Phillip; Schmid, Martina [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany); Bartsch, Peter [Beuth Hochschule für Technik Berlin, Fachbereich VIII Maschinenbau, Veranstaltungstechnik, Verfahrenstechnik (Germany); Fiechter, Sebastian; Lux-Steiner, Martha Ch. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany); Fischer, Christian-Herbert [Freie Universität Berlin, Institute of Chemistry and Biochemistry (Germany)

    2017-04-15

    Ag nanoparticles have attracted interest for plasmonic absorption enhancement of solar cells. For this purpose, well-defined particle sizes and densities as well as very low deposition temperatures are required. Thus, we report here a new spray chemical vapour deposition method for producing Ag NP films with independent size and density control at substrate temperatures even below 100 °C, which is much lower than for many other techniques. This method can be used on different substrates to deposit Ag NP films. It is a reproducible, low-cost process which uses trimethylphosphine (hexafluoroacetylacetonato) silver as a precursor in alcoholic solution. By systematic variation of deposition parameters and classic experiments, mechanisms of particle growth and of deposition processes as well as the low decomposition temperature of the precursor could be explained. Using the 3D finite element method, absorption spectra of selected samples were simulated, which fitted well with the measured results. Hence, further applications of such Ag NP films for generating plasmonic near field can be predicted by the simulation.

  9. Size- and density-controlled deposition of Ag nanoparticle films by a novel low-temperature spray chemical vapour deposition method—research into mechanism, particle growth and optical simulation

    International Nuclear Information System (INIS)

    Liu, Yang; Plate, Paul; Hinrichs, Volker; Köhler, Tristan; Song, Min; Manley, Phillip; Schmid, Martina; Bartsch, Peter; Fiechter, Sebastian; Lux-Steiner, Martha Ch.; Fischer, Christian-Herbert

    2017-01-01

    Ag nanoparticles have attracted interest for plasmonic absorption enhancement of solar cells. For this purpose, well-defined particle sizes and densities as well as very low deposition temperatures are required. Thus, we report here a new spray chemical vapour deposition method for producing Ag NP films with independent size and density control at substrate temperatures even below 100 °C, which is much lower than for many other techniques. This method can be used on different substrates to deposit Ag NP films. It is a reproducible, low-cost process which uses trimethylphosphine (hexafluoroacetylacetonato) silver as a precursor in alcoholic solution. By systematic variation of deposition parameters and classic experiments, mechanisms of particle growth and of deposition processes as well as the low decomposition temperature of the precursor could be explained. Using the 3D finite element method, absorption spectra of selected samples were simulated, which fitted well with the measured results. Hence, further applications of such Ag NP films for generating plasmonic near field can be predicted by the simulation.

  10. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt

    1987-01-01

    The author describes a Petri net model, called coloured Petri nets (CP-nets), by means of which it is possible to describe large systems without having to cope with unnecessary details. The author introduces CP-nets and provide a first impression of their modeling power and the suitability...

  11. Learning Visual Basic NET

    CERN Document Server

    Liberty, Jesse

    2009-01-01

    Learning Visual Basic .NET is a complete introduction to VB.NET and object-oriented programming. By using hundreds of examples, this book demonstrates how to develop various kinds of applications--including those that work with databases--and web services. Learning Visual Basic .NET will help you build a solid foundation in .NET.

  12. Growth modes and epitaxy of FeAl thin films on a-cut sapphire prepared by pulsed laser and ion beam assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Xiang; Trautvetter, Moritz; Ziemann, Paul [Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany); Wiedwald, Ulf [Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany); Fakultät für Physik, Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg (Germany)

    2014-01-14

    FeAl films around equiatomic composition are grown on a-cut (112{sup ¯}0) sapphire substrates by ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD) at ambient temperature. Subsequent successive annealing is used to establish chemical order and crystallographic orientation of the films with respect to the substrate. We find a strongly [110]-textured growth for both deposition techniques. Pole figures prove the successful preparation of high quality epitaxial films by PLD with a single in-plane orientation. IBAD-grown films, however, exhibit three in-plane orientations, all of them with broad angular distributions. The difference of the two growth modes is attributed to the existence of a metastable intermediate crystalline orientation as concluded from nonassisted sputter depositions at different substrate temperatures. The formation of the chemically ordered crystalline B2 phase is accompanied by the expected transition from ferromagnetic to paramagnetic behavior of the films. In accordance with the different thermally induced structural recovery, we find a step-like magnetic transition to paramagnetic behavior after annealing for 1 h at T{sub A} = 300 °C for IBAD deposition, while PLD-grown films show a gradual decrease of ferromagnetic signals with rising annealing temperatures.

  13. Graphene crystal growth by thermal precipitation of focused ion beam induced deposition of carbon precursor via patterned-iron thin layers

    Directory of Open Access Journals (Sweden)

    Rius Gemma

    2014-01-01

    Full Text Available Recently, relevant advances on graphene as a building block of integrated circuits (ICs have been demonstrated. Graphene growth and device fabrication related processing has been steadily and intensively powered due to commercial interest; however, there are many challenges associated with the incorporation of graphene into commercial applications which includes challenges associated with the synthesis of this material. Specifically, the controlled deposition of single layer large single crystal graphene on arbitrary supports, is particularly challenging. Previously, we have reported the first demonstration of the transformation of focused ion beam induced deposition of carbon (FIBID-C into patterned graphitic layers by metal-assisted thermal treatment (Ni foils. In this present work, we continue exploiting the FIBID-C approach as a route for graphene deposition. Here, thin patterned Fe layers are used for the catalysis of graphenization and graphitization. We demonstrate the formation of high quality single and few layer graphene, which evidences, the possibility of using Fe as a catalyst for graphene deposition. The mechanism is understood as the minute precipitation of atomic carbon after supersaturation of some iron carbides formed under a high temperature treatment. As a consequence of the complete wetting of FIBID-C and patterned Fe layers, which enable graphene growth, the as-deposited patterns do not preserve their original shape after the thermal treatment

  14. Comparative study of post-growth annealing of Cu(hfac)2, Co2(CO)8 and Me2Au(acac) metal precursors deposited by FEBID.

    Science.gov (United States)

    Puydinger Dos Santos, Marcos Vinicius; Szkudlarek, Aleksandra; Rydosz, Artur; Guerra-Nuñez, Carlos; Béron, Fanny; Pirota, Kleber Roberto; Moshkalev, Stanislav; Diniz, José Alexandre; Utke, Ivo

    2018-01-01

    Non-noble metals, such as Cu and Co, as well as noble metals, such as Au, can be used in a number modern technological applications, which include advanced scanning-probe systems, magnetic memory and storage, ferroelectric tunnel junction memristors, metal interconnects for high performance integrated circuits in microelectronics and nano-optics applications, especially in the areas of plasmonics and metamaterials. Focused-electron-beam-induced deposition (FEBID) is a maskless direct-write tool capable of defining 3-dimensional metal deposits at nanometre scale for above applications. However, codeposition of organic ligands when using organometallic precursors is a typical problem that limits FEBID of pure metal nanostructures. In this work, we present a comparative study using a post-growth annealing protocol at 100, 200, and 300 °C under high vacuum on deposits obtained from Co 2 (CO) 8 , Cu(II)(hfac) 2 , and Me 2 Au(acac) to study improvements on composition and electrical conductivity. Although the as-deposited material was similar for all precursors, metal grains embedded in a carbonaceous matrix, the post-growth annealing results differed. Cu-containing deposits showed the formation of pure Cu nanocrystals at the outer surface of the initial deposit for temperatures above 100 °C, due to the migration of Cu atoms from the carbonaceous matrix containing carbon, oxygen, and fluorine atoms. The average size of the Cu crystals doubles between 100 and 300 °C of annealing temperature, while the composition remains constant. In contrast, for Co-containing deposits oxygen release was observed upon annealing, while the carbon content remained approximately constant; the cobalt atoms coalesced to form a metallic film. The as-deposited Au-containing material shows subnanometric grains that coalesce at 100 °C, maintaining the same average size at annealing temperatures up to 300 °C. Raman analysis suggests that the amorphous carbonaceous matrix of the as-written Co

  15. Growth of centimeter-scale atomically thin MoS{sub 2} films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Gene; Venkata Subbaiah, Y. P.; Prestgard, Megan C.; Tiwari, Ashutosh, E-mail: tiwari@eng.utah.edu [Nanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)

    2015-05-01

    We are reporting the growth of single layer and few-layer MoS{sub 2} 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 MoS{sub 2} target. The material thus ablated was deposited on a single crystal sapphire (0001) substrate kept at 700 °C in an ambient vacuum of 10{sup −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 MoS{sub 2} target by 50 laser pulses (energy density: 1.5 J/cm{sup 2}) was found to result in the formation of a monolayer of MoS{sub 2} as shown by AFM results. In the Raman spectrum, A{sub 1g} and E{sup 1}{sub 2g} peaks were observed at 404.6 cm{sup −1} and 384.5 cm{sup −1} with a spacing of 20.1 cm{sup −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 MoS{sub 2} 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 MoS{sub 2} films were prepared. It was found that as the number of monolayers (n) in the MoS{sub 2} films increases, the spacing between the A{sub 1g} and E{sup 1}{sub 2g} Raman peaks (Δf) increases following an empirical relation, Δf=26.45−(15.42)/(1+1.44 n{sup 0.9}) cm{sup −1}.

  16. Parameters study on the growth of GaAs nanowires on indium tin oxide by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dan; Tang, Xiaohong, E-mail: exhtang@ntu.edu.sg, E-mail: wangk@sustc.edu.cn; Li, Xianqiang [OPTIMUS, Photonics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Wang, Kai, E-mail: exhtang@ntu.edu.sg, E-mail: wangk@sustc.edu.cn [Department of Electrical & Electronic Engineering, South University of Science and Technology of China, 1088 Xueyuan Avenue, Shenzhen 518055 (China); Olivier, Aurelien [CINTRA UMI 3288, School of Electrical and Electronic Engineering, Nanyang Technological University, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, 637553 Singapore (Singapore)

    2016-03-07

    After successful demonstration of GaAs nanowire (NW) epitaxial growth on indium tin oxide (ITO) by metal organic chemical vapor deposition, we systematically investigate the effect of growth parameters' effect on the GaAs NW, including temperature, precursor molar flow rates, growth time, and Au catalyst size. 40 nm induced GaAs NWs are observed with zinc-blende structure. Based on vapor-liquid-solid mechanism, a kinetic model is used to deepen our understanding of the incorporation of growth species and the role of various growth parameters in tuning the GaAs NW growth rate. Thermally activated behavior has been investigated by variation of growth temperature. Activation energies of 40 nm Au catalyst induced NWs are calculated at different trimethylgallium (TMGa) molar flow rates about 65 kJ/mol. The GaAs NWs growth rates increase with TMGa molar flow rates whereas the growth rates are almost independent of growth time. Due to Gibbs-Thomson effect, the GaAs NW growth rates increase with Au nanoparticle size at different temperatures. Critical radius is calculated as 2.14 nm at the growth condition of 430 °C and 1.36 μmol/s TMGa flow rate. It is also proved experimentally that Au nanoparticle below the critical radius such as 2 nm cannot initiate the growth of NWs on ITO. This theoretical and experimental growth parameters investigation enables great controllability over GaAs NWs grown on transparent conductive substrate where the methodology can be expanded to other III–V material NWs and is critical for potential hybrid solar cell application.

  17. Simulation of the Dynamics of Isothermal Growth of Single-Layer Graphene on a Copper Catalyst in the Process of Chemical Vapor Deposition of Hydrocarbons

    Science.gov (United States)

    Futko, S. I.; Shulitskii, B. G.; Labunov, V. A.; Ermolaeva, E. M.

    2018-01-01

    A new kinetic model of isothermal growth of single-layer graphene on a copper catalyst as a result of the chemical vapor deposition of hydrocarbons on it at a low pressure has been developed on the basis of in situ measurements of the growth of graphene in the process of its synthesis. This model defines the synthesis of graphene with regard for the chemisorption and catalytic decomposition of ethylene on the surface of a copper catalyst, the diffusion of carbon atoms in the radial direction to the nucleation centers within the thin melted near-surface copper layer, and the nucleation and autocatalytic growth of graphene domains. It is shown that the time dependence of the rate of growth of a graphene domain has a characteristic asymmetrical bell-like shape. The dependences of the surface area and size of a graphene domain and the rate of its growth on the time at different synthesis temperatures and ethylene concentrations have been obtained. Time characteristics of the growth of graphene domains depending on the parameters of their synthesis were calculated. The results obtained can be used for determining optimum regimes of synthesis of graphene in the process of chemical vapor deposition of hydrocarbons on different catalysts with a low solubility of carbon.

  18. Macular Atrophy Development and Subretinal Drusenoid Deposits in Anti-Vascular Endothelial Growth Factor Treated Age-Related Macular Degeneration.

    Science.gov (United States)

    Zarubina, Anna V; Gal-Or, Orly; Huisingh, Carrie E; Owsley, Cynthia; Freund, K Bailey

    2017-12-01

    To explore the association between presence of subretinal drusenoid deposits (SDD) at baseline in eyes with neovascular age-related macular degeneration (nAMD) with the development of macular atrophy (MA) during anti-vascular endothelial growth factor (VEGF) therapy. There were 74 eyes without pre-existing MA receiving anti-VEGF therapy for nAMD for 2 years or longer analyzed. At least two image modalities that included spectral-domain optical coherence tomography, near-infrared reflectance, fluorescein angiography, and color fundus photos were used to assess for SDD presence, phenotype (dot and ribbon), and location, neovascularization type, and MA. Logistic regression models using generalized estimating equations assessed the association between SDD and the development of MA adjusting for age, neovascularization type, and choroidal thickness. SDD were present in 46 eyes (63%) at baseline. MA developed in 38 eyes (51%) during the mean of 4.7 ± 1.2 years of follow-up. Compared with eyes without SDD, those with SDD at baseline were 3.0 times (95% confidence interval [CI] 1.1-8.5, P = 0.0343) more likely to develop MA. Eyes with SDD present in the inferior macula and inferior extramacular fields at baseline were 3.0 times and 6.5 times more likely to develop MA at follow-up than eyes without SDD in these locations (95% CI 1.0-8.9, P = 0.0461 and 95% CI 1.3-32.4, P = 0.0218, respectively). MA development was not associated with a specific SDD phenotype. MA frequently developed in eyes during anti-VEGF treatment. SDD were independently associated with MA development. The extension of SDD into the inferior fundus, particularly in the inferior extramacular field, conferred higher odds of subsequent MA development.

  19. Dislocation confinement in the growth of Na flux GaN on metalorganic chemical vapor deposition-GaN

    International Nuclear Information System (INIS)

    Takeuchi, S.; Asazu, H.; Nakamura, Y.; Sakai, A.; Imanishi, M.; Imade, M.; Mori, Y.

    2015-01-01

    We have demonstrated a GaN growth technique in the Na flux method to confine c-, (a+c)-, and a-type dislocations around the interface between a Na flux GaN crystal and a GaN layer grown by metalorganic chemical vapor deposition (MOCVD) on a (0001) sapphire substrate. Transmission electron microscopy (TEM) clearly revealed detailed interface structures and dislocation behaviors that reduced the density of vertically aligned dislocations threading to the Na flux GaN surface. Submicron-scale voids were formed at the interface above the dislocations with a c component in MOCVD-GaN, while no such voids were formed above the a-type dislocations. The penetration of the dislocations with a c component into Na flux GaN was, in most cases, effectively blocked by the presence of the voids. Although some dislocations with a c component in the MOCVD-GaN penetrated into the Na flux GaN, their propagation direction changed laterally through the voids. On the other hand, the a-type dislocations propagated laterally and collectively near the interface, when these dislocations in the MOCVD-GaN penetrated into the Na flux GaN. These results indicated that the dislocation propagation behavior was highly sensitive to the type of dislocation, but all types of dislocations were confined to within several micrometers region of the Na flux GaN from the interface. The cause of void formation, the role of voids in controlling the dislocation behavior, and the mechanism of lateral and collective dislocation propagation are discussed on the basis of TEM results

  20. Effect of ambient-level gas-phase peroxides on foliar injury, growth, and net photosynthesis in Japanese radish (Raphanus sativus)

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xuan, E-mail: xuan66chen@yahoo.co.j [Chinese Research Academy of Environmental Science, No.8, Dayangfang, Anwai, Chaoyang District, Beijing 100012 (China); Aoki, Masatoshi [Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu-shi, Tokyo 183-8509 (Japan); Takami, Akinori [National Institute for Environmental Studies, Onogawa 16-2, Tsukuba-shi, Ibaraki 305-8506 (Japan); Chai Fahe [Chinese Research Academy of Environmental Science, No.8, Dayangfang, Anwai, Chaoyang District, Beijing 100012 (China); Hatakeyama, Shiro [Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu-shi, Tokyo 183-8509 (Japan)

    2010-05-15

    To investigate the effects of ambient-level gas-phase peroxides concurrent with O{sub 3} on foliar injury, photosynthesis, and biomass in herbaceous plants, we exposed Japanese radish (Raphanus sativus) to clean air, 50 ppb O{sub 3}, 100 ppb O{sub 3}, and 2-3 ppb peroxides + 50 ppb O{sub 3} in outdoor chambers. Compared with exposure to 100 ppb O{sub 3}, exposure to 2-3 ppb peroxides + 50 ppb O{sub 3} induced greater damage in foliar injury, net photosynthetic rates and biomass; the pattern of foliar injury and the cause of net photosynthetic rate reduction also differed from those occurring with O{sub 3} exposure alone. These results indicate for the first time that sub-ppb peroxides + 50 ppb O{sub 3} can cause more severe damage to plants than 100 ppb O{sub 3}, and that not only O{sub 3}, but also peroxides, could be contributing to the herbaceous plant damage and forest decline observed in Japan's air-polluted urban and remote mountains areas. - Ambient-level gas-phase peroxides coexisted with 50 ppb O{sub 3} may contribute to the herbaceous plants damage and forest decline observed in Japan.

  1. Direct growth of Ge1-xSnx films on Si using a cold-wall ultra-high-vacuum chemical-vapor-deposition system

    Directory of Open Access Journals (Sweden)

    Aboozar eMosleh

    2015-04-01

    Full Text Available Germanium tin alloys were grown directly on Si substrate at low temperatures using a cold-wall ultra-high vacuum chemical vapor deposition system. Epitaxial growth was achieved by adopting commercial gas precursors of germane and stannic chloride without any carrier gases. The X-ray diffraction analysis showed the incorporation of Sn and that the Ge1-xSnx films are fully epitaxial and strain relaxed. Tin incorporation in the Ge matrix was found to vary from 1% to 7%. The scanning electron microscopy images and energy dispersive X-ray spectra maps show uniform Sn incorporation and continuous film growth. Investigation of deposition parameters shows that at high flow rates of stannic chloride the films were etched due to the production of HCl. The photoluminescence study shows the reduction of bandgap from 0.8 eV to 0.55 eV as a result of Sn incorporation.

  2. High-voltage vertical GaN Schottky diode enabled by low-carbon metal-organic chemical vapor deposition growth

    Science.gov (United States)

    Cao, Y.; Chu, R.; Li, R.; Chen, M.; Chang, R.; Hughes, B.

    2016-02-01

    Vertical GaN Schottky barrier diode (SBD) structures were grown by metal-organic chemical vapor deposition on free-standing GaN substrates. The carbon doping effect on SBD performance was studied by adjusting the growth conditions and spanning the carbon doping concentration between ≤3 × 1015 cm-3 and 3 × 1019 cm-3. Using the optimized growth conditions that resulted in the lowest carbon incorporation, a vertical GaN SBD with a 6-μm drift layer was fabricated. A low turn-on voltage of 0.77 V with a breakdown voltage over 800 V was obtained from the device.

  3. Changes in conifer and deciduous forest foliar and forest floor chemistry and basal area tree growth across a nitrogen (N) deposition gradient in the northeastern US

    Science.gov (United States)

    Johnny L. Boggs; Steven G. McNulty; Linda H. Pardo

    2007-01-01

    We evaluated foliar and forest floor chemistry across a gradient of N deposition in the Northeast at 11 red spruce (Picea rubens Sarg.) sites in 1987/1988 and foliar and forest floor chemistry and basal area growth at six paired spruce and deciduous sites in 1999. The six red spruce plots were a subset of the original 1987/1988 spruce sites. In 1999...

  4. Selective growth of Ge1- x Sn x epitaxial layer on patterned SiO2/Si substrate by metal-organic chemical vapor deposition

    Science.gov (United States)

    Takeuchi, Wakana; Washizu, Tomoya; Ike, Shinichi; Nakatsuka, Osamu; Zaima, Shigeaki

    2018-01-01

    We have investigated the selective growth of a Ge1- x Sn x epitaxial layer on a line/space-patterned SiO2/Si substrate by metal-organic chemical vapor deposition. We examined the behavior of a Sn precursor of tributyl(vinyl)tin (TBVSn) during the growth on Si and SiO2 substrates and investigated the effect of the Sn precursor on the selective growth. The selective growth of the Ge1- x Sn x epitaxial layer was performed under various total pressures and growth temperatures of 300 and 350 °C. The selective growth of the Ge1- x Sn x epitaxial layer on the patterned Si region is achieved at a low total pressure without Ge1- x Sn x growth on the SiO2 region. In addition, we found that the Sn content in the Ge1- x Sn x epitaxial layer increases with width of the SiO2 region for a fixed Si width even with low total pressure. To control the Sn content in the selective growth of the Ge1- x Sn x epitaxial layer, it is important to suppress the decomposition and migration of Sn and Ge precursors.

  5. Planning of nets

    International Nuclear Information System (INIS)

    Carberry, M

    1996-01-01

    The paper is about the planning of nets in areas of low density like it is the case of the rural areas. The author includes economic and technological aspects, planning of nets, demands and management among others

  6. Annotating Coloured Petri Nets

    DEFF Research Database (Denmark)

    Lindstrøm, Bo; Wells, Lisa Marie

    2002-01-01

    Coloured Petri nets (CP-nets) can be used for several fundamentally different purposes like functional analysis, performance analysis, and visualisation. To be able to use the corresponding tool extensions and libraries it is sometimes necessary to include extra auxiliary information in the CP......-net. An example of such auxiliary information is a counter which is associated with a token to be able to do performance analysis. Modifying colour sets and arc inscriptions in a CP-net to support a specific use may lead to creation of several slightly different CP-nets – only to support the different uses...... of the same basic CP-net. One solution to this problem is that the auxiliary information is not integrated into colour sets and arc inscriptions of a CP-net, but is kept separately. This makes it easy to disable this auxiliary information if a CP-net is to be used for another purpose. This paper proposes...

  7. Surface poisoning in the nucleation and growth of palladium atomic layer deposition with Pd(hfac){sub 2} and formalin

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, D.N. [Department of Chemistry and Biochemistry, University of Colorado, 215 UCB, Boulder, CO 80309 (United States); George, S.M., E-mail: Steven.George@Colorado.Edu [Department of Chemistry and Biochemistry, University of Colorado, 215 UCB, Boulder, CO 80309 (United States); Department of Chemical and Biological Engineering, University of Colorado, 424 UCB, Boulder, CO (United States)

    2011-06-01

    Palladium (Pd) atomic layer deposition (ALD) can be performed with Pd(hfac){sub 2} (hfac = hexafluoroacetyl-acetone) and formalin as the reactants. For Pd ALD on oxide surfaces, the nucleation of Pd ALD has been observed to require between 20 and 100 ALD cycles. To understand the long nucleation periods, this study explored the surface reactions occurring during Pd ALD nucleation and growth on hydroxylated Al{sub 2}O{sub 3} substrates. In situ Fourier transform infrared (FTIR) spectroscopy on high surface area nanopowders was used to observe the surface species. The adsorption of Pd(hfac){sub 2} on hydroxylated Al{sub 2}O{sub 3} substrates was found to yield both Pd(hfac)* and Al(hfac)* surface species. The identity of the Al(hfac)* species was confirmed by separate FTIR studies of hfacH adsorption on the hydroxylated Al{sub 2}O{sub 3} substrates. Isothermal loss of the Al(hfac)* species revealed second-order kinetics at 448-523 K with an activation barrier of E{sub d} = 39.4 kcal/mol. The lack of correlation between Al(hfac)* and AlOH* species during the loss of Al(hfac)* species suggested that the Al(hfac)* species may desorb as Al(hfac){sub 3}. After Pd(hfac){sub 2} exposure and the subsequent formalin exposure on hydroxylated Al{sub 2}O{sub 3} substrates, only hfac ligands from Pd(hfac)* species were removed from the surface. In addition, the formalin exposure added formate species. The Al(hfac)* species was identified as the cause of the long nucleation period because Al(hfac)* behaves as a site blocker. The surface poisoning by Al(hfac)* species was corroborated by adsorbing hfacH prior to the Pd(hfac){sub 2} exposures. The amount of Pd(hfac)* species after Pd(hfac){sub 2} exposures decreased progressively versus the previous hfacH exposure. Pd ALD occurred gradually during the subsequent Pd ALD cycles as the Al(hfac)* species were slowly removed from the Al{sub 2}O{sub 3} surface. Ex situ transmission electron microscopy analysis revealed Pd nanoclusters

  8. Chemical vapor deposition growth of single-crystalline cesium lead halide microplatelets and heterostructures for optoelectronic applications

    Institute of Scientific and Technical Information of China (English)

    Yiliu Wang; Xun Guan; Dehui Li; Hung-Chieh Cheng; Xidong Duan; Zhaoyang Lin; Xiangfeng Duan

    2017-01-01

    Orgaruc-inorganic hybrid halide perovskites,such as CH3NH3PbI3,have emerged as an exciting class of materials for solar photovoltaic applications;however,they are currently plagued by insufficient environmental stability.To solve this issue,all-inorganic halide perovskites have been developed and shown to exhibit significantly improved stability.Here,we report a single-step chemical vapor deposition growth of cesium lead halide (CsPbX3) microcrystals.Optical microscopy studies show that the resulting perovskite crystals predominantly adopt a square-platelet morphology.Powder X-ray diffraction (PXRD) studies of the resulting crystals demonstrate a highly crystalline nature,with CsPbC13,CsPbBr3,and CsPbI3 showing tetragonal,monoclinic,and orthorhombic phases,respectively.Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies show that the resulting platelets exhibit well-faceted structures with lateral dimensions of the order of 10-50 μm,thickness around 1 μm,and ultra-smooth surface,suggesting the absence of obvious grain boundaries and the single-crystalline nature of the individual microplatelets.Photoluminescence (PL) images and spectroscopic studies show a uniform and intense emission consistent with the expected band edge transition.Additionally,PL images show brighter emission around the edge of the platelets,demonstrating a wave-guiding effect in high-quality crystals.With a well-defined geometry and ultra-smooth surface,the square platelet structure can function as a whispering gallery mode cavity with a quality factor up to 2,863 to support laser emission at room temperature.Finally,we demonstrate that such microplatelets can be readily grown on a variety of substrates,including silicon,graphene,and other two-dimensional materials such as molybdenum disulfide,which can readily allow the construction of heterostructure optoelectronic devices,including a graphene/perovskite/ graphene vertically-stacked photodetector with

  9. Secondary growth mechanism of SiGe islands deposited on a mixed-phase microcrystalline Si by ion beam co-sputtering.

    Science.gov (United States)

    Ke, S Y; Yang, J; Qiu, F; Wang, Z Q; Wang, C; Yang, Y

    2015-11-06

    We discuss the SiGe island co-sputtering deposition on a microcrystalline silicon (μc-Si) buffer layer and the secondary island growth based on this pre-SiGe island layer. The growth phenomenon of SiGe islands on crystalline silicon (c-Si) is also investigated for comparison. The pre-SiGe layer grown on μc-Si exhibits a mixed-phase structure, including SiGe islands and amorphous SiGe (a-SiGe) alloy, while the layer deposited on c-Si shows a single-phase island structure. The preferential growth and Ostwald ripening growth are shown to be the secondary growth mechanism of SiGe islands on μc-Si and c-Si, respectively. This difference may result from the effect of amorphous phase Si (AP-Si) in μc-Si on the island growth. In addition, the Si-Ge intermixing behavior of the secondary-grown islands on μc-Si is interpreted by constructing the model of lateral atomic migration, while this behavior on c-Si is ascribed to traditional uphill atomic diffusion. It is found that the aspect ratios of the preferential-grown super islands are higher than those of the Ostwald-ripening ones. The lower lateral growth rate of super islands due to the lower surface energy of AP-Si on the μc-Si buffer layer for the non-wetting of Ge at 700 °C and the stronger Si-Ge intermixing effect at 730 °C may be responsible for this aspect ratio difference.

  10. Boron mediation on the growth of Ge quantum dots on Si (1 0 0) by ultra high vacuum chemical vapor deposition system

    International Nuclear Information System (INIS)

    Chen, P.S.; Pei, Z.; Peng, Y.H.; Lee, S.W.; Tsai, M.-J.

    2004-01-01

    Self-assembled Ge quantum dots (QDs) with boron mediation are grown on Si (1 0 0) by an industrial hot wall ultra-high-vacuum chemical vapor deposition (UHV/CVD) system with different growth temperatures and dopant gas flow rates. Diborane (B 2 H 6 ) gas is applied as a surfactant on the Si (1 0 0) prior to the growth of Ge QDs. Small dome and pyramid shaped Ge QDs are observed after boron treatment as compared to the hut shaped Ge cluster without boron pre-treatment at 525 and 550 deg. C. The Ge QDs have a typical base width and height of about 30 and 6 nm, respectively, and the density is about 2.5x10 10 cm -2 for the growth temperature of 525 deg. C. Through weakening the Si-H bond during the epitaxy growth and changing the stress field on the surface of the Si (1 0 0) buffer, boron mediation can modify the growth mode of Ge QDs. When the growth temperature is low (525-550 deg. C), the former factor is dominate, as the growth temperature is raised (600 deg. C), the latter parameter may play an important role on the formation of Ge QDs. Optical transition from Ge QDs is demonstrated from photoluminescence (PL) spectra. Furthermore, multifold Ge/Si layers are also carried out to enhance the PL intensity with first Ge layer treated by B 2 H 6 and avoid the generation of threading dislocations

  11. Direct visualization of initial SEI morphology and growth kinetics during lithium deposition by in situ electrochemical transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sacci, Robert L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science adn Technology Division; Dudney, Nancy J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science adn Technology Division; More, Karren L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Parent, Lucas R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Fundamental and Computational Sciences Directorate; Arslan, Ilke [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Fundamental and Computational Sciences Directorate; Browning, Nigel D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Fundamental and Computational Sciences Directorate; Unocic, Raymond R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science

    2013-12-20

    Deposition of Li is a major safety concern existing in Li-ion secondary batteries. We perform the first in situ high spatial resolution measurement coupled with real-time quantitative electrochemistry to characterize SEI formation on gold using a standard battery electrolyte. We also demonstrate that a dendritic SEI forms prior to Li deposition and that it remains on the surface after Li electrodissolution.

  12. Note: Influence of rinsing and drying routines on growth of multilayer thin films using automated deposition system.

    Science.gov (United States)

    Gamboa, Daniel; Priolo, Morgan A; Ham, Aaron; Grunlan, Jaime C

    2010-03-01

    A versatile, high speed robot for layer-by-layer deposition of multifunctional thin films, which integrates concepts from previous dipping systems, has been designed with dramatic improvements in software, positioning, rinsing, drying, and waste removal. This system exploits the electrostatic interaction of oppositely charged species to deposit nanolayers (1-10 nm thick) from water onto the surface of a substrate. Dip times and number of deposited layers are adjustable through a graphical user interface. In between dips the system spray rinses and dries the substrate by positioning it in the two-tiered rinse-dry station. This feature significantly reduces processing time and provides the flexibility to choose from four different procedures for rinsing and drying. Assemblies of natural montmorillonite clay and polyethylenimine are deposited onto 175 microm poly(ethylene terephthalate) film to demonstrate the utility of this automated deposition system. By altering the type of rinse-dry procedure, these clay-based assemblies are shown to exhibit variations in film thickness and oxygen transmission rate. This type of system reproducibly deposits films containing 20 or more layers and may also be useful for other types of coatings that make use of dipping.

  13. Thin film silicon by a microwave plasma deposition technique: Growth and devices, and, interface effects in amorphous silicon/crystalline silicon solar cells

    Science.gov (United States)

    Jagannathan, Basanth

    Thin film silicon (Si) was deposited by a microwave plasma CVD technique, employing double dilution of silane, for the growth of low hydrogen content Si films with a controllable microstructure on amorphous substrates at low temperatures (prepared by this technique. Such films showed a dark conductivity ˜10sp{-6} S/cm, with a conduction activation energy of 0.49 eV. Film growth and properties have been compared for deposition in Ar and He carrier systems and growth models have been proposed. Low temperature junction formation by undoped thin film silicon was examined through a thin film silicon/p-type crystalline silicon heterojunctions. The thin film silicon layers were deposited by rf glow discharge, dc magnetron sputtering and microwave plasma CVD. The hetero-interface was identified by current transport analysis and high frequency capacitance methods as the key parameter controlling the photovoltaic (PV) response. The effect of the interface on the device properties (PV, junction, and carrier transport) was examined with respect to modifications created by chemical treatment, type of plasma species, their energy and film microstructure interacting with the substrate. Thermally stimulated capacitance was used to determine the interfacial trap parameters. Plasma deposition of thin film silicon on chemically clean c-Si created electron trapping sites while hole traps were seen when a thin oxide was present at the interface. Under optimized conditions, a 10.6% efficient cell (11.5% with SiOsb2 A/R) with an open circuit voltage of 0.55 volts and a short circuit current density of 30 mA/cmsp2 was fabricated.

  14. 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

  15. Effect of Different Feeding on Feed Conversion and Growth of Common Carp (Cyprinus carpio in Floating Net Cage Culture at Jatiluhur Dike

    Directory of Open Access Journals (Sweden)

    N.B.P Utomo

    2007-01-01

    Full Text Available This experiment was conducted to evaluate the effectiveness of two feeding methods commonly used in cage culture of carp Cyprinus carpio at Jatiluhur Lake, Purwakarta. Common carp in mean weight of 24.29±4.29 gram were reared in floating net cage 7×7×3 m3, for 70 days rearing.  Fish were fed on a commercial diet containing 30% protein at 5 times daily.  Experimental treatment was feeding technique, i.e., by 6% of body weight, and at satiation for the second treatment.  The results showed that the application of "at satiation feeding method" was more effective than "fixed method" (6% of body weight indicating with food conversion ratio of 1.86 versus 1.91. Production of fish fed on the diet using at satiation method for 70 days was 1,241 kg/cage. Keywords: common carp, Cyprinus carpio, FCR, floating net cage, at satiation   ABSTRAK Salah satu cara untuk menekan biaya dalam usaha budidaya ikan secara intensif adalah dengan penggunaan pakan secera efisien agar ikan tumbuh optimal dan pakan yang terbuang seminimal mungkin. Penelitian dilakukan di Waduk Jatiluhur, Purwakarta.  Ikan mas (Cyprinus carpio ukuran bobot awal rata-rata 24,29±4,29 gram dipelihara dalam jaring apung ukuran 7×7×3 m3, selama 70 hari.  Ikan diberi pakan dengan frekuensi yang sama sebanyak 5 kali/hari. Perlakuan pada penelitian ini adalah teknik pemberian pakan, yaitu ikan pada jaring pertama diberi pakan sebanyak 6% dari bobot biomassa, sementara pada jaring kedua ikan diberi pakan sekenyangnya (at satiation.  Hasil penelitian menunjukkan bahwa pemberian pakan dengan metode sekenyangnya (at satiation menghasilkan nilai FCR sebesar 1,86 yang relatif lebih efisien dibandingkan dengan sebanyak 6% berdasarkan bobot biomassa (1,91. Produktivitas akhir ikan dengan pemberian pakan sekenyangnya 70 hari pemeliharaan dalam jaring apung di waduk Jatiluhur mencapai 1.241 kg. Kata kunci: ikan mas, Cyprinus carpio, FCR, Keramba jaring apung, at satiation

  16. Post-growth annealing of zinc oxide thin films pulsed laser deposited under enhanced oxygen pressure on quartz and silicon substrates

    International Nuclear Information System (INIS)

    Rusop, M.; Uma, K.; Soga, T.; Jimbo, T.

    2006-01-01

    Zinc oxide (ZnO) thin films have been prepared by pulsed laser deposition (PLD) technique at room temperature on quartz and single crystal silicon (1 0 0) substrates. The oxygen ambient gas pressure was attained at 6 Torr during the deposition. The deposited films were post-growth annealed in air at various annealing temperatures for 30 min. The X-ray diffraction (XRD), optical and electrical properties have been measured to study the properties of the films as a function of annealing temperatures. XRD has shown the strength of (0 0 2) peak increases and FWHM value decreases as the annealing temperatures increases from 200 to 600 deg. C. The post-growth annealed at 600 deg. C show dominant c-axis oriented hexagonal wurtize crystal structure and exhibit high average transmittance about 85% in the visible region and very sharp absorption edge at 376 nm with energy band gap of approximately 3.46 eV. Electrical measurement indicates the resistivity decreases with the annealing temperatures up to 600 deg. C, after which it increases with higher annealing temperatures at 800 deg. C. The complex of oxygen vacancy in the ZnO films may be the source of low conductivity in undoped ZnO films

  17. Growth, microstructure, and field-emission properties of synthesized diamond film on adamantane-coated silicon substrate by microwave plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Tiwari, Rajanish N.; Chang Li

    2010-01-01

    Diamond nucleation on unscratched Si surface is great importance for its growth, and detailed understanding of this process is therefore desired for many applications. The pretreatment of the substrate surface may influence the initial growth period. In this study, diamond films have been synthesized on adamantane-coated crystalline silicon {100} substrate by microwave plasma chemical vapor deposition from a gaseous mixture of methane and hydrogen gases without the application of a bias voltage to the substrates. Prior to adamantane coating, the Si substrates were not pretreated such as abraded/scratched. The substrate temperature was ∼530 deg. C during diamond deposition. The deposited films are characterized by scanning electron microscopy, Raman spectrometry, x-ray diffraction, and x-ray photoelectron spectroscopy. These measurements provide definitive evidence for high-crystalline quality diamond film, which is synthesized on a SiC rather than clean Si substrate. Characterization through atomic force microscope allows establishing fine quality criteria of the film according to the grain size of nanodiamond along with SiC. The diamond films exhibit a low-threshold (55 V/μm) and high current-density (1.6 mA/cm 2 ) field-emission (FE) display. The possible mechanism of formation of diamond films and their FE properties have been demonstrated.

  18. The influence of charge effect on the growth of hydrogenated amorphous silicon by the hot-wire chemical vapor deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Q.; Nelson, B.P.; Iwaniczko, E.; Mahan, A.H.; Crandall, R.S.; Benner, J. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    The authors observe at lower substrate temperatures that the scatter in the dark conductivity on hydrogenated amorphous silicon (a-Si:H) films grown on insulating substrates (e.g., Corning 7059 glass) by the hot-wire chemical vapor deposition technique (HWCVD) can be five orders of magnitude or more. This is especially true at deposition temperatures below 350 C. However, when the authors grow the same materials on substrates with a conductive grid, virtually all of their films have acceptable dark conductivity (< 5 {times} 10{sup {minus}10} S/cm) at all deposition temperatures below 425 C. This is in contrast to only about 20% of the materials grown in this same temperature range on insulating substrates having an acceptable dark conductivity. The authors estimated an average energy of 5 eV electrons reaching the growing surface in vacuum, and did additional experiments to see the influence of both the electron flux and the energy of the electrons on the film growth. Although these effects do not seem to be important for growing a-Si:H by HWCVD on conductive substrates, they help better understand the important parameters for a-Si:H growth, and thus, to optimize these parameters in other applications of HWCVD technology.

  19. Effects of various deposition times and RF powers on CdTe thin film growth using magnetron sputtering

    Science.gov (United States)

    Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

    2016-09-01

    Cadmium telluride (CdTe) is a p-type II-VI compound semiconductor, which is an active component for producing photovoltaic solar cells in the form of thin films, due to its desirable physical properties. In this study, CdTe film was deposited using the radio frequency (RF) magnetron sputtering system onto a glass substrate. To improve the properties of the CdTe film, effects of two experimental parameters of deposition time and RF power were investigated on the physical properties of the CdTe films. X-ray Diffraction (XRD), atomic force microscopy (AFM) and spectrophotometer were used to study the structural, morphological and optical properties of the CdTe samples grown at different experimental conditions, respectively. Our results suggest that film properties strongly depend on the experimental parameters and by optimizing these parameters, it is possible to tune the desired structural, morphological and optical properties. From XRD data, it is found that increasing the deposition time and RF power leads to increasing the crystallinity as well as the crystal sizes of the grown film, and all the films represent zinc blende cubic structure. Roughness values given from AFM images suggest increasing the roughness of the CdTe films by increasing the RF power and deposition times. Finally, optical investigations reveal increasing the film band gaps by increasing the RF power and the deposition time.

  20. Growth and characterization of ZnO films deposited by chemical bath and annealed by microwaves (CBD-A{mu}W)

    Energy Technology Data Exchange (ETDEWEB)

    DIaz-Reyes, J [CIBA-IPN, Ex-Hacienda de San Juan Molino, Km. 1.5, Tepetitla, Tlaxcala, 90700 (Mexico); Martinez-Juarez, J; Garcia, M L; Galeazzi, R [CIDS-ICUAP, BUAP, 14 Sur y San Claudio S/N, CU. Edif. No. 137, Col. San Manuel, Puebla, Puebla 72570 (Mexico); Juarez, G, E-mail: jdiazr2001@yahoo.com [DIE-SEES, CINVESTAV-IPN, A. P. 14-740, Mexico, D. F. 07000 (Mexico)

    2010-06-15

    A study of the growth and the physical properties of ZnO films deposited by chemical bath technique and annealed by microwave are presented. For the deposition solution the molar ratio between zinc nitrate and urea is varied in a range of 1:1... 1:10. By X-ray obtains that layers have hexagonal polycrystalline wurtzite type unitary cell. The Raman spectra show the first order experimental Raman spectra of ZnO. The first order Raman modes are identified in the ZnO Raman spectra. The 300K photoluminescence shows radiative bands labelled by red, yellow, green and violet bands, which are associated to defects of oxygen and zinc vacancies. By EDS measurements determined their stoichiometry, which allows relating it with the intensity of radiative bands associated to oxygen and zinc vacancies.

  1. Physical, optical and electrical properties of copper selenide (CuSe) thin films deposited by solution growth technique at room temperature

    International Nuclear Information System (INIS)

    Gosavi, S.R.; Deshpande, N.G.; Gudage, Y.G.; Sharma, Ramphal

    2008-01-01

    Copper selenide (CuSe) thin films are grown onto amorphous glass substrate from an aqueous alkaline medium using solution growth technique (SGT) at room temperature. The preparative parameters were optimized to obtain good quality of thin films. The as-deposited films were characterized for physical, optical and electrical properties. X-ray diffraction (XRD) pattern reveals that the films are polycrystalline in nature. Energy dispersive analysis by X-ray (EDAX) shows formation of stoichiometric CuSe compound. Uniform deposition of CuSe thin films on glass substrate was observed from scanning electron microscopy (SEM) and atomic force microscopy (AFM) micrographs. Average grain size was determined to 144.53 ± 10 nm using atomic force microscopy. The band gap was found to be 2.03 eV with direct band-to-band transition. Semi-conducting behaviour was observed from resistivity measurements. Ohmic behaviour was seen from I-V curve with good electrical conductivity

  2. Growth

    Science.gov (United States)

    John R. Jones; George A. Schier

    1985-01-01

    This chapter considers aspen growth as a process, and discusses some characteristics of the growth and development of trees and stands. For the most part, factors affecting growth are discussed elsewhere, particularly in the GENETICS AND VARIATION chapter and in chapters in PART 11. ECOLOGY. Aspen growth as it relates to wood production is examined in the WOOD RESOURCE...

  3. Investigation of erosion and deposition on wall components of TEXTOR-94

    International Nuclear Information System (INIS)

    Wienhold, P.; Esser, H.G.; Kirschner, A.; Philipps, V.; Seggern, J. von; Ohya, K.; Rubel, M.

    1999-01-01

    The paper describes in the first part the formation of carbon flakes up to 10-20 μm thickness (average growth rate 2 nm/s) on the graphite tiles of the toroidal belt limiter. This occurred as a consequence of a slight change of the geometry and turned parts of the surface area from net erosion into net deposition zones. The possible influence of the morphology on this behaviour is discussed in the second part by means of an erosion experiment where the gradual disappearance of a boron substrate could be discriminated from the simultaneous carbon deposition on the surface. The two counter-acting processes co-exist within 10-30 μm distance and lead to an extremely non-uniform carbon deposition even in net erosion zones. The carbon agglomeration coincides with surface imperfections, e.g. grooves, but agglomeration by temperature enhanced mobility is not excluded. The changeover from net deposition to net erosion averaged over larger distances can still be observed and is due to the hydrogen and carbon fluxes in the SOL. This is confirmed by Monte-Carlo code calculations. (orig.)

  4. Effects of Surface Modification of Nanodiamond Particles for Nucleation Enhancement during Its Film Growth by Microwave Plasma Jet Chemical Vapour Deposition Technique

    Directory of Open Access Journals (Sweden)

    Chii-Ruey Lin

    2014-01-01

    Full Text Available The seedings of the substrate with a suspension of nanodiamond particles (NDPs were widely used as nucleation seeds to enhance the growth of nanostructured diamond films. The formation of agglomerates in the suspension of NDPs, however, may have adverse impact on the initial growth period. Therefore, this paper was aimed at the surface modification of the NDPs to enhance the diamond nucleation for the growth of nanocrystalline diamond films which could be used in photovoltaic applications. Hydrogen plasma, thermal, and surfactant treatment techniques were employed to improve the dispersion characteristics of detonation nanodiamond particles in aqueous media. The seeding of silicon substrate was then carried out with an optimized spin-coating method. The results of both Fourier transform infrared spectroscopy and dynamic light scattering measurements demonstrated that plasma treated diamond nanoparticles possessed polar surface functional groups and attained high dispersion in methanol. The nanocrystalline diamond films deposited by microwave plasma jet chemical vapour deposition exhibited extremely fine grain and high smooth surfaces (~6.4 nm rms on the whole film. These results indeed open up a prospect of nanocrystalline diamond films in solar cell applications.

  5. The growth of nanoscale ZnO films by pulsed-spray evaporation chemical vapor deposition and their structural, electric and optical properties

    International Nuclear Information System (INIS)

    Jiang Yinzhu; Bahlawane, Naoufal

    2010-01-01

    Great interest in nanoscale thin films (sub-100 nm) has been stimulated by the developing demands of functional devices. In this paper, nanoscale zinc oxide (ZnO) thin films were deposited on glass substrates at 300 o C by pulsed-spray evaporation chemical vapor deposition. Scanning electron micrographs indicate uniform surface morphologies composed of nanometer-sized spherical particles. The growth kinetics and growth mode are studied and the relationship between the film thickness and the electric properties with respect to the growth mode is interpreted. X-ray diffraction shows that all ZnO films grown by this process were crystallized in a hexagonal structure and highly oriented with their c-axes perpendicular to the plane of the substrate. Optical measurements show transparencies above 85% in the visible spectral range for all films. The absorbance in the UV spectral range respects well the Beer-Lambert law, enabling an accurate optical thickness measurement, and the absorption coefficient was measured for a selected wavelength. The measured band gap energies exhibit an almost constant value of 3.41 eV for all films with different thicknesses, which attributed to the thickness-independent crystallite size.

  6. Quantum net dynamics

    International Nuclear Information System (INIS)

    Finkelstein, D.

    1989-01-01

    The quantum net unifies the basic principles of quantum theory and relativity in a quantum spacetime having no ultraviolet infinities, supporting the Dirac equation, and having the usual vacuum as a quantum condensation. A correspondence principle connects nets to Schwinger sources and further unifies the vertical structure of the theory, so that the functions of the many hierarchic levels of quantum field theory (predicate algebra, set theory, topology,hor-ellipsis, quantum dynamics) are served by one in quantum net dynamics

  7. Growth and properties of Al-rich InxAl1-xN ternary alloy grown on GaN template by metalorganic chemical vapour deposition

    International Nuclear Information System (INIS)

    Oh, Tae Su; Suh, Eun-Kyung; Kim, Jong Ock; Jeong, Hyun; Lee, Yong Seok; Nagarajan, S; Lim, Kee Young; Hong, Chang-Hee

    2008-01-01

    An Al-rich In x Al 1-x N ternary alloy was grown on a GaN template by metal-organic chemical vapour deposition (MOCVD). The GaN template was fabricated on a c-plane sapphire with a low temperature GaN nucleation layer. The growth of the 300 nm thick In x Al 1-x N layer was carried out under various growth temperatures and pressures. The surface morphology and the InN molar fraction of the In x Al 1-x N layer were assessed by using atomic force microscopy (AFM) and high resolution x-ray diffraction, respectively. The AFM surface images of the In x Al 1-x N ternary alloy exhibited quantum dot-like grains caused by the 3D island growth mode. The grains, however, disappeared rapidly by increasing diffusion length and mobility of the Al adatoms with increasing growth temperature and the full width at half maximum value of ternary peaks in HR-XRD decreased with decreasing growth pressure. The MOCVD growth condition with the increased growth temperature and decreased growth pressure would be effective to grow the In x Al 1-x N ternary alloy with a smooth surface and improved quality. The optical band edge of In x Al 1-x N ternary alloys was estimated by optical absorbance and, based on the results of HR-XRD and optical absorbance measurements, we obtained the bowing parameter of the In x Al 1-x N ternary alloy at b = 5.3 eV, which was slightly larger than that of previous reports

  8. Growth of Cu2ZnSnS4(CZTS) by Pulsed Laser Deposition for Thin film Photovoltaic Absorber Material

    Science.gov (United States)

    Nandur, Abhishek; White, Bruce

    2014-03-01

    CZTS (Cu2ZnSnS4) has become the subject of intense interest because it is an ideal candidate absorber material for thin-film solar cells with an optimal band gap (1.5 eV), high absorption coefficient (104 cm-1) and abundant elemental components. Pulsed Laser Deposition (PLD) provides excellent control over film composition since thin films are deposited under high vacuum with excellent stoichiometry transfer from the target. CZTS thin films were deposited using PLD from a stoichiometrically close CZTS target (Cu2.6Zn1.1Sn0.7S3.44). The effects of laser energy fluence and substrate temperature and post-deposition sulfur annealing on the surface morphology, composition and optical absorption have been investigated. Optimal CZTS thin films exhibited a band gap of 1.54 eV with an absorption coefficient of 4x104cm-1. A solar cell utilizing PLD grown CZTS with the structure SLG/Mo/CZTS/CdS/ZnO/ITO showed a conversion efficiency of 5.85% with Voc = 376 mV, Jsc = 38.9 mA/cm2 and Fill Factor, FF = 0.40.

  9. Substrate-biasing during plasma-assisted atomic layer deposition to tailor metal-oxide thin film growth

    NARCIS (Netherlands)

    Profijt, H. B.; M. C. M. van de Sanden,; Kessele, W. M. M.

    2013-01-01

    Two substrate-biasing techniques, i.e., substrate-tuned biasing and RF biasing, have been implemented in a remote plasma configuration, enabling control of the ion energy during plasma-assisted atomic layer deposition (ALD). With both techniques, substrate bias voltages up to -200 V have been

  10. Crystalline phase control and growth selectivity of β-MnO{sub 2} thin films by remote plasma assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abi-Akl, M.; Tabbal, M., E-mail: malek.tabbal@aub.edu.lb; Kassem, W.

    2016-08-01

    In this paper, we exploit the effect of coupling an oxygen remote plasma source to Pulsed Laser Deposition (PLD) for the growth of pure and well crystallized β-MnO{sub 2} films. Films were grown on Si substrates by laser ablation of a MnO target in oxygen ambient and remote plasma. X-Ray Diffraction, Fourier Transform Infra-Red spectroscopy and Raman scattering were used to determine the crystalline structure and bonding in the grown layers, whereas Atomic Force Microscopy was used to study their morphology and surface roughness. Deposition at 500 °C and high oxygen pressure (33.3–66.6 Pa) resulted in the formation of films with roughness of 12 nm consisting of nsutite γ-MnO{sub 2}, a structure characterized by the intergrowth of the pyrolusite β-MnO{sub 2} in a ramsdellite R-MnO{sub 2} matrix. Deposition at the same temperature but low pressure (1.33–3.33 Pa) in oxygen ambient lead to the formation of Mn{sub 2}O{sub 3} whereas plasma activation within the same pressure range induced the growth of single phase highly crystalline β-MnO{sub 2} having smooth surfaces with a roughness value of 0.6 nm. Such results underline the capability of remote plasma assisted PLD in selecting and controlling the crystalline phase of manganese oxide layers. - Highlights: • MnO{sub 2} films were grown by Remote Plasma Assisted Pulsed Laser Deposition. • Crystalline MnO{sub 2} is formed at a substrate temperature of 500 °C. • Smooth crystalline single phase β-MnO{sub 2} films were obtained at 1.33–3.33 Pa. • Deposition at 1.33–3.33 Pa without plasma activation lead to the growth of Mn{sub 2}O{sub 3}. • Without plasma, mixed phases of MnO{sub 2} polymorphs are obtained at 33.3 Pa and above.

  11. Programming NET Web Services

    CERN Document Server

    Ferrara, Alex

    2007-01-01

    Web services are poised to become a key technology for a wide range of Internet-enabled applications, spanning everything from straight B2B systems to mobile devices and proprietary in-house software. While there are several tools and platforms that can be used for building web services, developers are finding a powerful tool in Microsoft's .NET Framework and Visual Studio .NET. Designed from scratch to support the development of web services, the .NET Framework simplifies the process--programmers find that tasks that took an hour using the SOAP Toolkit take just minutes. Programming .NET

  12. Game Coloured Petri Nets

    DEFF Research Database (Denmark)

    Westergaard, Michael

    2006-01-01

    This paper introduces the notion of game coloured Petri nets. This allows the modeler to explicitly model what parts of the model comprise the modeled system and what parts are the environment of the modeled system. We give the formal definition of game coloured Petri nets, a means of reachability...... analysis of this net class, and an application of game coloured Petri nets to automatically generate easy-to-understand visualizations of the model by exploiting the knowledge that some parts of the model are not interesting from a visualization perspective (i.e. they are part of the environment...

  13. Direct growth of large grain polycrystalline silicon films on aluminum-induced crystallization seed layer using hot-wire chemical vapor deposition

    International Nuclear Information System (INIS)

    Wu, Bing-Rui; Lo, Shih-Yung; Wuu, Dong-Sing; Ou, Sin-Liang; Mao, Hsin-Yuan; Wang, Jui-Hao; Horng, Ray-Hua

    2012-01-01

    Large grain polycrystalline silicon (poly-Si) films on glass substrates have been deposited on an aluminum-induced crystallization (AIC) seed layer using hot-wire chemical vapor deposition (HWCVD). A poly-Si seed layer was first formed by the AIC process and a thicker poly-Si film was subsequently deposited upon the seed layer using HWCVD. The effects of AIC annealing parameters on the structural and electrical properties of the poly-Si seed layers were characterized by Raman scattering spectroscopy, field-emission scanning electron microscopy, and Hall measurements. It was found that the crystallinity of seed layer was enhanced with increasing the annealing duration and temperature. The poly-Si seed layer formed at optimum annealing parameters can reach a grain size of 700 nm, hole concentration of 3.5 × 10 18 cm −3 , and Hall mobility of 22 cm 2 /Vs. After forming the seed layer, poly-Si films with good crystalline quality and high growth rate (> 1 nm/s) can be obtained using HWCVD. These results indicated that the HWCVD-deposited poly-Si film on an AIC seed layer could be a promising candidate for thin-film Si photovoltaic applications. - Highlights: ►Poly-Si seed layers are formed by aluminum-induced crystallization (AIC) process. ►Poly-Si on AIC seed layers are prepared by hot-wire chemical vapor deposition. ►AIC process parameters affect structural properties of poly-Si films. ►Increasing the annealing duration and temperature increases the film crystallinity.

  14. Growth mechanism and elemental distribution of beta-Ga2O3 crystalline nanowires synthesized by cobalt-assisted chemical vapor deposition.

    Science.gov (United States)

    Wang, Hui; Lan, Yucheng; Zhang, Jiaming; Crimp, Martin A; Ren, Zhifeng

    2012-04-01

    Long beta-Ga2O3 crystalline nanowires are synthesized on patterned silicon substrates using chemical vapor deposition technique. Advanced electron microscopy indicates that the as-grown beta-Ga2O3 nanowires are consisted of poly-crystalline (Co, Ga)O tips and straight crystalline beta-Ga2O3 stems. The catalytic cobalt not only locates at the nanowire tips but diffuses into beta-Ga2O3 nanowire stems several ten nanometers. A solid diffusion growth mechanism is proposed based on the spatial elemental distribution along the beta-Ga2O3 nanowires at nanoscale.

  15. Investigation of growth and characterization of nanostructured CuIn5S8 thin films produced by glancing angle deposition

    International Nuclear Information System (INIS)

    Sinaoui, A.; Chaffar-Akkari, F.; Gallas, B.; Demaille, D.; Kanzari, M.

    2015-01-01

    Ternary chalcogenide of copper and indium (CuIn 5 S 8 ) thin films were grown by thermal evaporation method using GLancing Angle Deposition (GLAD) technique. The samples were prepared under different incident angles (α = 0°, 40°, 60° and 85° measured from the normal to the substrate surface) with a substrate rotation of 2 rpm. X-ray diffraction, scanning electron microscopy, and ultraviolet–visible-infrared spectra are employed to characterize the microstructure and optical properties of the CuIn 5 S 8 thin films deposited by this technique. Under the GLAD conditions, we demonstrate that with substrate rotation, the columns were grown vertically due to the shadowing symmetry. The optical constants of the deposited films were determined from the analysis of transmission and reflection data. The results show that the refractive index and the thickness were decreased as α rises from 0° to 85° while the porosity and the Urbach energy were increased with increasing of the incident angle. The minimum refractive index is found to be 2.03 for the helical CuIn 5 S 8 film deposited at an angle of 85° and the Urbach energy was found to increase from 0.29 to 0.5 eV as α rises from 0° to 85°. Such changes of the optical behaviors are correlated with changes of the microstructure, especially a porous architecture which is favored for high incident angle. These properties exhibit potential for use in applications such as photonic crystals, graded index optical filters, and birefrigent omnidirectional reflectors. - Highlights: • GLancing angle deposition technique was employed to prepare CuIn 5 S 8 thin films. • CuIn 5 S 8 films exhibit a spinel structure with a preferred orientation along 311. • With substrate rotation, the columns were grown vertically due to shadowing symmetry. • The refractive index decreases with increasing glancing angle deposition. • Variations of the optical behaviors were correlated to the highly porous structure

  16. In situ growth of Co nanofibers in In2O3-SnO2 matrix during sputtering deposition

    International Nuclear Information System (INIS)

    Echigoya, Jun-ichi; Sano, Junichi

    2006-01-01

    Co-sputtering onto (001) cubic zirconia from a target of indium tin oxide (ITO) partially covered by cobalt (Co) was carried out at substrate temperatures of 470-770 K in order to investigate the growth of Co nanofibers. During film growth, Co forms fibers in the growth direction in the single-crystalline ITO matrix. The cross section of the Co fibers, the size of which depends on the substrate temperature, was a rectangle with an edge 1-5 nm in length. The edge length of the Co fiber increased with the increase of the substrate temperature. The present method is attractive for application to produce magnetic recording media

  17. Ga N nano wires and nano tubes growth by chemical vapor deposition method at different NH{sub 3} flow rate

    Energy Technology Data Exchange (ETDEWEB)

    Li, P.; Liu, Y.; Meng, X. [Wuhan University, School of Physics and Technology, Key Laboratory of Artificial Micro and Nanostructures of Ministry of Education, Wuhan 430072 (China)

    2016-11-01

    Ga N nano wires and nano tubes have been successfully synthesized via the simple chemical vapor deposition method. NH{sub 3} flow rate was found to be a crucial factor in the synthesis of different type of Ga N which affects the shape and the diameter of generated Ga N nano structures. X-ray diffraction confirms that Ga N nano wires grown on Si(111) substrate under 900 degrees Celsius and with NH{sub 3} flow rate of 50 sc cm presents the preferred orientation growth in the (002) direction. It is beneficial to the growth of nano structure through catalyst annealing. Transmission electron microscopy and scanning electron microscopy were used to measure the size and structures of the samples. (Author)

  18. Investigation of the formation of deposits of calcium sulfate on a metallic wall: detection and growth initiation

    International Nuclear Information System (INIS)

    Guillermin, Roger

    1970-01-01

    Whereas the formation of calcium sulfate deposits on walls of (water desalination) heat exchanger tubes increases the load loss and decreases the heat exchange coefficient, measuring the load loss or measuring heat transfer in an exchanger could be a method to determine whether scaling occurs. In this research thesis, the author aims at a computational assessing of the sensitivity of such methods in conditions easily obtained in laboratory and allowing, if possible, the identification of the different steps of deposit formation. Then, the author considers some discontinuous methods, possibly more sensitive but more difficult to adjust, but which are not interesting in an industrial point of view: methods based on weighing, on chemical dosing, on radioactive measurements (tracers, auto-radiography, beta backscattering), optical methods and electric methods (piezoelectric quartz, conductivity measurements)

  19. Growth and characterization of V{sub 2}O{sub 5} nanorods deposited by spray pyrolysis at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Abd-Alghafour, N. M., E-mail: na2013bil@gmail.com; Ahmed, Naser M., E-mail: nas-tiji@yahoo.com; Hassan, Zai. [Iraqi Ministry of Education, Anbar-Iraq (Iraq); Mohammad, Sabah M. [Nano-Optoelectronics Research and Technology Laboratory School of Physics, university sains Malaysia, 11800 Penang (Malaysia); Bououdina, M. [Nanotechnology Centre, University of Bahrain, PO Box 32038, Kingdom of Bahrain Department of Physics, College of Science, University of Bahrain, PO Box 32038, Kingdom of Bahrain, Iraqi Ministry of Education (Bahrain)

    2016-07-06

    Vanadium pentoxide (V{sub 2}O{sub 5}) nanorods were deposited by spray pyrolysis on preheated glass substrates at low temperatures. The influence of substrate temperature on the crystallization of V{sub 2}O{sub 5} has been investigated. X-ray diffraction analysis (XRD) revealed that the films deposited at T{sub sub} = 300°C were orthorhombic structures with preferential along (001) direction. Formation of nanorods from substrate surface which led to the formation of films with small-sized and rod-shaped nanostructure is observed by field scanning electron microscopy. Optical transmittance in the visible range increases to reach a maximum value of about 80% for a substrate temperature of 350°C. PL spectra reveal one main broad peak centered around 540 nm with high intensity.

  20. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt

    1991-01-01

    This paper describes how Coloured Petri Nets (CP-nets) have been developed — from being a promising theoretical model to being a full-fledged language for the design, specification, simulation, validation and implementation of large software systems (and other systems in which human beings and...

  1. Net zero water

    CSIR Research Space (South Africa)

    Lindeque, M

    2013-01-01

    Full Text Available the national grid. The unfortunate situation with water is that there is no replacement technology for water. Water can be supplied from many different sources. A net zero energy development will move closer to a net zero water development by reducing...

  2. Construction of monophase nets

    International Nuclear Information System (INIS)

    Suarez A, Jose Antonio

    1996-01-01

    The paper refers to the use of monophase loads in commercial residential urbanizations and in small industries, for this reason it is considered unnecessary the construction of three-phase nets. The author makes a historical recount of these nets in Bogota, his capacities, uses and energy savings

  3. Features of copper coatings growth at high-rate deposition using magnetron sputtering systems with a liquid metal target

    Czech Academy of Sciences Publication Activity Database

    Bleykher, G.A.; Borduleva, A.O.; Yuryeva, A.V.; Krivobokov, V.P.; Lančok, Ján; Bulíř, Jiří; Drahokoupil, Jan; Klimša, Ladislav; Kopeček, Jaromír; Fekete, Ladislav; Čtvrtlík, Radim; Tomáštík, Jan

    2017-01-01

    Roč. 324, Sep (2017), s. 111-120 ISSN 0257-8972 R&D Projects: GA MŠk LO1409; GA MŠk LM2015088 Institutional support: RVO:68378271 Keywords : magnetron sputtering * evaporation * high-rate coating deposition * coating properties * Cu coatings Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.589, year: 2016

  4. The growth of the metallic ZrNx thin films on P-GaN substrate by pulsed laser deposition

    Science.gov (United States)

    Gu, Chengyan; Sui, Zhanpeng; Li, Yuxiong; Chu, Haoyu; Ding, Sunan; Zhao, Yanfei; Jiang, Chunping

    2018-03-01

    Although metal nitride thin films have attractive prospects in plasmonic applications due to its stable properties in harsh environments containing high temperatures, shock, and contaminants, the effect of deposition parameters on the properties of the metallic ZrN grown on III-N semiconductors by pulse laser deposition still lacks of detailed exploration. Here we have successfully prepared metallic ZrNx films on p-GaN substrate by pulsed laser deposition in N2 ambient of various pressures at a fixed substrate temperature (475 °C). It is found that the films exhibit quite smooth surfaces and (111) preferred orientation. The X-ray photoelectron spectroscopy measurements indicate that carbon contamination can be completely removed and oxygen contamination is significantly reduced on the film surfaces after cleaning using Ar+ sputtering. The N/Zr ratio increases from 0.64 to 0.75 when the N2 pressure increases from 0.5 Pa to 3 Pa. The optical reflectivity spectra measured by the UV-vis-NIR spectrophotometer show that the ZrNx is a typical and good metallic-like material and its metallic properties can be tuned with changing the film compositions.

  5. Fusion through the NET

    International Nuclear Information System (INIS)

    Spears, B.

    1987-01-01

    The paper concerns the next generation of fusion machines which are intended to demonstrate the technical viability of fusion. In Europe, the device that will follow on from JET is known as NET - the Next European Torus. If the design programme for NET proceeds, Europe could start to build the machine in 1994. The present JET programme hopes to achieve breakeven in the early 1990's. NET hopes to reach ignition in the next century, and so lay the foundation for a demonstration reactor. A description is given of the technical specifications of the components of NET, including: the first wall, the divertors to protect the wall, the array of magnets that provide the fields containing the plasma, the superconducting magnets, and the shield of the machine. NET's research programme is briefly outlined, including the testing programme to optimise conditions in the machine to achieve ignition, and its safety work. (U.K.)

  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

    2014-05-16

    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 were simulated by varying the deposition energy of carbon atoms in the range of 1-120 eV. Intrinsic film characteristics (e.g. density and internal stress) were determined after the system reached equilibrium. Short- and intermediate-range carbon atom ordering is examined in the context of atomic hybridization and ring connectivity simulation results. It is shown that relatively high deposition energy (i.e., 80 eV) yields a multilayer film structure consisting of an intermixing layer, bulk film and surface layer, consistent with the classical subplantation model. The highest film density (3.3 g cm-3), sp3 fraction (∼43%), and intermediate-range carbon atom ordering correspond to a deposition energy of ∼80 eV, which is in good agreement with experimental findings. © 2014 IOP Publishing Ltd.

  7. A study of the effects of aligned vertically growth time on ZnO nanorods deposited for the first time on Teflon substrate

    Science.gov (United States)

    Farhat, O. F.; Halim, M. M.; Ahmed, Naser M.; Oglat, Ammar A.; Abuelsamen, A. A.; Bououdina, M.; Qaeed, M. A.

    2017-12-01

    In this study, ZnO nanorods (NRs) were well deposited on Teflon substrates (PTFE) via a chemical bath deposition (CBD) method at low temperature. The consequences of growth time (1 h-4 h) on the structural and optical properties of the aligned ZnO (NRs) were investigated through X-ray diffraction, field-emission scanning electron microscopy (FESEM), and photoluminescence (PL) analyses. The results show that the ZnO (NRs) were preferred to grew aligned along the c-axis as hexagonal wurtzite structure as proved by the sharp and strong ZnO (002) peaks of the ZnO (NRs). Irrespective of the growth continuation, FESEM photos confirmed that the ZnO nanorods arrays were fit to be aligned along the c-axis and perpendicular to (PTFE) substrates. The ZnO nanorods that exhibited the sharper stand most intense PL peaks among the sample were grown for 3hs as demonstrated by PL spectra. The device further showed a sensitivity of 4068 to low-power (1.25 mW/cm2) 375 nm light pulses without an external bias. The measurements of photoresponse demonstrated the highly reproducible characteristics of the fabricated UV detector with rapid response and baseline recovery times of 48.05 ms. Thus, this work introduced a simple, low-cost method of fabricating rapid-response, and highly photosensitive UV detectors with zero power consumption on Teflon substrates.

  8. Epitaxial growth of mixed conducting layered Ruddlesden–Popper Lan+1NinO3n+1 (n = 1, 2 and 3) phases by pulsed laser deposition

    International Nuclear Information System (INIS)

    Wu, Kuan-Ting; Soh, Yeong-Ah; Skinner, Stephen J.

    2013-01-01

    Graphical abstract: - Highlights: • High quality epitaxial thin films of layered Ruddlesden–Popper nickelates were prepared. • For the first time this has been achieved by the PLD process. • n = 1, 2 and 3 films were successfully deposited on SrTiO 3 and NdGaO 3 substrates. • c-Axis oriented films were confirmed by XRD analysis. • In-plane and out-of-plane strain effects on lattice are discussed. - Abstract: Layered Ruddlesden–Popper phases of composition La n+1 Ni n O 3n+1 (n = 1, 2 and 3) have been epitaxially grown on SrTiO 3 (0 0 1) or NdGaO 3 (1 1 0) single crystal substrates using the pulsed laser deposition technique. X-ray diffraction analyses (θ/2θ, rocking curves, and φ-scans) and atomic force microscopy confirms the high-quality growth of the series of films with low surface roughness values (less than 1 nm). In particular, epitaxial growth of the higher order phases (n = 2 and 3) of lanthanum nickelate have been demonstrated for the first time

  9. Synergistic interactions of CO2 enrichment and nitrogen deposition promote growth and ecophysiological advantages of invading Eupatorium adenophorum in Southwest China.

    Science.gov (United States)

    Lei, Yan-bao; Wang, Wei-bin; Feng, Yu-long; Zheng, Yu-long; Gong, He-de

    2012-10-01

    Global environmental change and ongoing biological invasions are the two prominent ecological issues threatening biodiversity worldwide, and investigations of their interaction will aid to predict plant invasions and inform better management strategies in the future. In this study, invasive Eupatorium adenophorum and native congener E. stoechadosmum were compared at ambient and elevated atmospheric carbon dioxide (CO(2)) concentrations combined with three levels of nitrogen (N; reduced, control and increased) in terms of growth, energy gain, and cost. Compared with E. stoechadosmum, E. adenophorum adopted a quicker-return energy-use strategy, i.e. higher photosynthetic energy-use efficiency and shorter payback time. Lower leaf mass per area may be a pivotal trait for the invader, which contributed to an increased N allocation to Rubisco at the expense of cell walls and therefore to higher photosynthetic energy gain. CO(2) enrichment and N deposition synergistically promoted plant growth and influenced some related ecophysiological traits, and the synergistic effects were greater for the invader than for the native congener. Reducing N availability by applying sugar eliminated the advantages of the invader over its native congener at both CO(2) levels. Our results indicate that CO(2) enrichment and N deposition may exacerbate E. adenophorum's invasion in the future, and manipulating environmental resources such as N availability may be a feasible tool for managing invasion impacts of E. adenophorum.

  10. 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.

  11. Effect of Growth Pressure on Epitaxial Graphene Grown on 4H-SiC Substrates by Using Ethene Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Shuxian Cai

    2015-08-01

    Full Text Available The Si(0001 face and C(000-1 face dependences on growth pressure of epitaxial graphene (EG grown on 4H-SiC substrates by ethene chemical vapor deposition (CVD was studied using atomic force microscopy (AFM and micro-Raman spectroscopy (μ-Raman. AFM revealed that EGs on Si-faced substrates had clear stepped morphologies due to surface step bunching. However, This EG formation did not occur on C-faced substrates. It was shown by μ-Raman that the properties of EG on both polar faces were different. EGs on Si-faced substrates were relatively thinner and more uniform than on C-faced substrates at low growth pressure. On the other hand, D band related defects always appeared in EGs on Si-faced substrates, but they did not appear in EG on C-faced substrate at an appropriate growth pressure. This was due to the μ-Raman covering the step edges when measurements were performed on Si-faced substrates. The results of this study are useful for optimized growth of EG on polar surfaces of SiC substrates.

  12. Analyses of the impact of changes in atmospheric deposition and climate on forest growth in European monitoring plots: A stand growth approach

    NARCIS (Netherlands)

    Solberg, S.; Dobbertin, M.; Reinds, G.J.; Andreassen, K.; Lange, H.; Garcia Fernandez, P.; Hildingsson, A.; Vries, de W.

    2009-01-01

    During the last 15 years a number of studies have shown increasing forest growth in central Europe, rather than a decline as was expected due to negative effects of air pollution. We have here used data from intensive monitoring plots spread over Europe for a five year period in order to examine the

  13. GeSn growth kinetics in reduced pressure chemical vapor deposition from Ge2H6 and SnCl4

    Science.gov (United States)

    Aubin, J.; Hartmann, J. M.

    2018-01-01

    We have investigated the low temperature epitaxy of high Sn content GeSn alloys in a 200 mm industrial Reduced Pressure - Chemical Vapor Deposition tool from Applied Materials. Gaseous digermane (Ge2H6) and liquid tin tetrachloride (SnCl4) were used as the Ge and Sn precursors, respectively. The impact of temperature (in the 300-350 °C range), Ge2H6 and SnCl4 mass-flows on the GeSn growth kinetics at 100 Torr has been thoroughly explored. Be it at 300 °C or 325 °C, a linear GeSn growth rate increase together with a sub-linear Sn concentration increase occurred as the SnCl4 mass-flow increased, irrespective of the Ge2H6 mass flow (fixed or varying). The Sn atoms seemed to catalyze H desorption from the surface, resulting in higher GeSn growth rates for high SnCl4 mass-flows (in the 4-21 nm min-1 range). The evolution of the Sn content x with the F (SnCl4) 2 ·/F (Ge2H6) mass-flow ratio was fitted by x2/(1 - x) = n ·F (SnCl4) 2 ·/F (Ge2H6), with n = 0.25 (325 °C) and 0.60 (300 °C). We have otherwise studied the impact of temperature, in the 300-350 °C range, on the GeSn growth kinetics. The GeSn growth rate exponentially increased with the temperature, from 15 up to 32 nm min-1. The associated activation energy was low, i.e. Ea = 10 kcal mol-1. Meanwhile, the Sn content decreased linearly as the growth temperature increased, from 15% at 300 °C down to 6% at 350 °C.

  14. Achieving high mobility ZnO : Al at very high growth rates by dc filtered cathodic arc deposition

    International Nuclear Information System (INIS)

    Mendelsberg, R J; Lim, S H N; Wallig, J; Anders, A; Zhu, Y K; Milliron, D J

    2011-01-01

    Achieving a high growth rate is paramount for making large-area transparent conducting oxide coatings at a low cost. Unfortunately, the quality of thin films grown by most techniques degrades as the growth rate increases. Filtered dc cathodic arc is a lesser known technique which produces a stream of highly ionized plasma, in stark contrast to the neutral atoms produced by standard sputter sources. Ions bring a large amount of potential energy to the growing surface which is in the form of heat, not momentum. By minimizing the distance from cathode to substrate, the high ion flux gives a very high effective growth temperature near the film surface without causing damage from bombardment. The high surface temperature is a direct consequence of the high growth rate and allows for high-quality crystal growth. Using this technique, 500-1300 nm thick and highly transparent ZnO : Al films were grown on glass at rates exceeding 250 nm min -1 while maintaining resistivity below 5 x 10 -4 Ω cm with electron mobility as high as 60 cm 2 V -1 s -1 . (fast track communication)

  15. Single-Step Seeded-Growth of Graphene Nanoribbons (GNRs) via Plasma-Enhanced Chemical Vapor Deposition (PECVD)

    Science.gov (United States)

    Hsu, C.-C.; Yang, K.; Tseng, W.-S.; Li, Yiliang; Li, Yilun; Tour, J. M.; Yeh, N.-C.

    One of the main challenges in the fabrication of GNRs is achieving large-scale low-cost production with high quality. Current techniques, including lithography and unzipped carbon nanotubes, are not suitable for mass production. We have recently developed a single-step PECVD growth process of high-quality graphene sheets without any active heating. By adding some substituted aromatic as seeding molecules, we are able to rapidly grow GNRs vertically on various transition-metal substrates. The morphology and electrical properties of the GNRs are dependent on the growth parameters such as the growth time, gas flow and species of the seeding molecules. On the other hand, all GNRs exhibit strong infrared and optical absorption. From studies of the Raman spectra, scanning electron microscopic images, and x-ray/ultraviolet photoelectron spectra of these GNRs as functions of the growth parameters, we propose a model for the growth mechanism. Our findings suggest that our approach opens up a pathway to large-scale, inexpensive production of GNRs for applications to supercapacitors and solar cells. This work was supported by the Grubstake Award and NSF through IQIM at Caltech.

  16. Tailoring Si(100) substrate surfaces for GaP growth by Ga deposition: A low-energy electron microscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Rienäcker, Michael; Borkenhagen, Benjamin, E-mail: b.borkenhagen@pe.tu-clausthal.de; Lilienkamp, Gerhard; Daum, Winfried [TU Clausthal, Institut für Energieforschung und Physikalische Technologien, Leibnizstraße 4, D-38678 Clausthal-Zellerfeld (Germany)

    2015-08-07

    For GaP-on-Si(100) heteroepitaxy, currently considered as a model system for monolithic integration of III–V semiconductors on Si(100), the surface steps of Si(100) have a major impact on the quality of the GaP film. Monoatomic steps cause antiphase domains in GaP with detrimental electronic properties. A viable route is to grow the III–V epilayer on single-domain Si(100) with biatomic steps, but preferably not at the expense of reduced terrace widths introduced by miscut substrates. We have performed in situ investigations of the influence of Ga deposition on the kinetics of surface steps and terraces of Si(100) at substrate temperatures above 600 °C by low-energy electron microscopy. Starting from nearly equally distributed T{sub A} and T{sub B} terraces of a two-domain Si(100) surface, submonolayer deposition of Ga results in a transformation into a surface dominated by T{sub A} terraces and biatomic D{sub A} steps. This transformation is reversible, and Si(100) with monoatomic steps is recovered upon termination of the Ga flux. Under conditions of higher coverages (but still below 0.25 monolayer), we observe restructuring into a surface with T{sub B} dominance, similar to the findings of Hara et al. [J. Appl. Phys. 98, 083515 (2005)]. The occurrence and mutual transformations of surface structures with different terrace and step structures in a narrow range of temperatures and Ga deposition rates is discussed.

  17. Growth and surface characterization of TiNbZr thin films deposited by magnetron sputtering for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Tallarico, D.A. [Federal University of Sao Carlos, Materials Science and Engineering Graduation Program, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, SP (Brazil); Gobbi, A.L. [Brazilian Nanotechnology National Laboratory, Rua Giuseppe Máximo Scolfaro 10.000, CEP 13083-100 Campinas, SP (Brazil); Paulin Filho, P.I. [Federal University of Sao Carlos, Department of Materials Engineering, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, SP (Brazil); Maia da Costa, M.E.H. [Pontifical Catholic University of Rio de Janeiro, Department of Physics, CEP 22451-900 Rio de Janeiro, RJ (Brazil); Nascente, P.A.P., E-mail: nascente@ufscar.br [Federal University of Sao Carlos, Department of Materials Engineering, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, SP (Brazil)

    2014-10-01

    Low modulus of elasticity and the presence of non-toxic elements are important criteria for the development of materials for implant applications. Low modulus Ti alloys can be developed by designing β-Ti alloys containing non-toxic alloying elements such as Nb and Zr. Actually, most of the metallic implants are produced with stainless steel (SS) because it has adequate bulk properties to be used as biomaterials for orthopedic or dental implants and is less expensive than Ti and its alloys, but it is less biocompatible than them. The coating of this SS implants with Ti alloy thin films may be one alternative to improve the biomaterial properties at a relatively low cost. Sputtering is a physical deposition technique that allows the formation of nanostructured thin films. Nanostructured surfaces are interesting when it comes to the bone/implant interface due to the fact that both the surface and the bone have nanoscale particle sizes and similar mechanical properties. TiNbZr thin films were deposited on both Si(111) and stainless steel (SS) substrates. The TiNbZr/Si(111) film was used as a model system, while the TiNbZr/SS film might improve the biocompatibility and extend the life time of stainless steel implants. The morphology, chemical composition, Young's modulus, and hardness of the films were analyzed by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and nanoindentation. - Highlights: • TiNbZr thin films were deposited on Si(111) and stainless steel (SS). • Their Young's modulus differences are within 5.3% and hardness 1.7%. • TiNbZr/SS film chemical composition remained almost constant with depth. • TiNbZr films presented nanostructured grains and low roughness for substrates. • TiNbZr/SS film hardness was about 100% greater than the SS substrate hardness.

  18. Growth and surface characterization of TiNbZr thin films deposited by magnetron sputtering for biomedical applications

    International Nuclear Information System (INIS)

    Tallarico, D.A.; Gobbi, A.L.; Paulin Filho, P.I.; Maia da Costa, M.E.H.; Nascente, P.A.P.

    2014-01-01

    Low modulus of elasticity and the presence of non-toxic elements are important criteria for the development of materials for implant applications. Low modulus Ti alloys can be developed by designing β-Ti alloys containing non-toxic alloying elements such as Nb and Zr. Actually, most of the metallic implants are produced with stainless steel (SS) because it has adequate bulk properties to be used as biomaterials for orthopedic or dental implants and is less expensive than Ti and its alloys, but it is less biocompatible than them. The coating of this SS implants with Ti alloy thin films may be one alternative to improve the biomaterial properties at a relatively low cost. Sputtering is a physical deposition technique that allows the formation of nanostructured thin films. Nanostructured surfaces are interesting when it comes to the bone/implant interface due to the fact that both the surface and the bone have nanoscale particle sizes and similar mechanical properties. TiNbZr thin films were deposited on both Si(111) and stainless steel (SS) substrates. The TiNbZr/Si(111) film was used as a model system, while the TiNbZr/SS film might improve the biocompatibility and extend the life time of stainless steel implants. The morphology, chemical composition, Young's modulus, and hardness of the films were analyzed by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and nanoindentation. - Highlights: • TiNbZr thin films were deposited on Si(111) and stainless steel (SS). • Their Young's modulus differences are within 5.3% and hardness 1.7%. • TiNbZr/SS film chemical composition remained almost constant with depth. • TiNbZr films presented nanostructured grains and low roughness for substrates. • TiNbZr/SS film hardness was about 100% greater than the SS substrate hardness

  19. Growth and characterization of epitaxial anatase TiO2(001) on SrTiO3-buffered Si(001) using atomic layer deposition

    International Nuclear Information System (INIS)

    McDaniel, M.D.; Posadas, A.; Wang, T.; Demkov, A.A.; Ekerdt, J.G.

    2012-01-01

    Epitaxial anatase titanium dioxide (TiO 2 ) films have been grown by atomic layer deposition (ALD) on Si(001) substrates using a strontium titanate (STO) buffer layer grown by molecular beam epitaxy (MBE) to serve as a surface template. The growth of TiO 2 was achieved using titanium isopropoxide and water as the co-reactants at a substrate temperature of 225–250 °C. To preserve the quality of the MBE-grown STO, the samples were transferred in-situ from the MBE chamber to the ALD chamber. After ALD growth, the samples were annealed in-situ at 600 °C in vacuum (10 −7 Pa) for 1–2 h. Reflection high-energy electron diffraction was performed during the MBE growth of STO on Si(001), as well as after deposition of TiO 2 by ALD. The ALD films were shown to be highly ordered with the substrate. At least four unit cells of STO must be present to create a stable template on the Si(001) substrate for epitaxial anatase TiO 2 growth. X-ray diffraction revealed that the TiO 2 films were anatase with only the (004) reflection present at 2θ = 38.2°, indicating that the c-axis is slightly reduced from that of anatase powder (2θ = 37.9°). Anatase TiO 2 films up to 100 nm thick have been grown that remain highly ordered in the (001) direction on STO-buffered Si(001) substrates. - Highlights: ► Epitaxial anatase films are grown by atomic layer deposition (ALD) on Si(001). ► Four unit cells of SrTiO 3 on silicon create a stable template for ALD. ► TiO 2 thin films have a compressed c-axis and an expanded a-axis. ► Up to 100 nm thick TiO 2 films remain highly ordered in the (001) direction.

  20. Net Zero Energy Buildings

    DEFF Research Database (Denmark)

    Marszal, Anna Joanna; Bourrelle, Julien S.; Gustavsen, Arild

    2010-01-01

    and identify possible renewable energy supply options which may be considered in calculations. Finally, the gap between the methodology proposed by each organisation and their respective national building code is assessed; providing an overview of the possible changes building codes will need to undergo......The international cooperation project IEA SHC Task 40 / ECBCS Annex 52 “Towards Net Zero Energy Solar Buildings”, attempts to develop a common understanding and to set up the basis for an international definition framework of Net Zero Energy Buildings (Net ZEBs). The understanding of such buildings...

  1. Getting to Net Zero

    Energy Technology Data Exchange (ETDEWEB)

    2016-09-01

    The technology necessary to build net zero energy buildings (NZEBs) is ready and available today, however, building to net zero energy performance levels can be challenging. Energy efficiency measures, onsite energy generation resources, load matching and grid interaction, climatic factors, and local policies vary from location to location and require unique methods of constructing NZEBs. It is recommended that Components start looking into how to construct and operate NZEBs now as there is a learning curve to net zero construction and FY 2020 is just around the corner.

  2. Pro NET Best Practices

    CERN Document Server

    Ritchie, Stephen D

    2011-01-01

    Pro .NET Best Practices is a practical reference to the best practices that you can apply to your .NET projects today. You will learn standards, techniques, and conventions that are sharply focused, realistic and helpful for achieving results, steering clear of unproven, idealistic, and impractical recommendations. Pro .NET Best Practices covers a broad range of practices and principles that development experts agree are the right ways to develop software, which includes continuous integration, automated testing, automated deployment, and code analysis. Whether the solution is from a free and

  3. EVALUATION OF FISH FAUNA STOCKS IN DAMS IN SOSSEGO MIME IN CANAÃ OF CARAJÁS (EASTERN AMAZON, CAPTURED WITH THE USE OF CAST NET BEFORE THE DEPOSIT OF TAILINGS

    Directory of Open Access Journals (Sweden)

    Ivan Furtado Junior

    2016-12-01

    Full Text Available This study aims to estimate the biomass of fish stocks in the area of the dam formed by tailings of Sossego mine in Canaã dos Carajás, captured with the use of cast nets for fish. The prospecting work was carried out during the period from 29 February to 6 March 2004, 6 months after closing the dam and immediately before the disposal of waste. The average values estimated for the capture per unit area covered by cast nets (CPUA and biomass were 8.4 g m-² and 16,922.7 kg, respectively. The most representative groups of fish were minnows, with 67.7% and discus with 24.8% of the total estimated biomass. The species caught were: Moenkhausia cf. sanctaefilomenae (redeye tetra fish, Tetragonopterus cf. argenteus (white tetra fish, Tetragonopterus chalceus (red tetra fish, Aequidens viridis (cichlasoma bimaculatum Crenicichla cincta (jacunda Hoplerythrinus unitaeniatus (jeju Curimata inornata (branquinha and Hoplias malabaricus (trahira. Keywords: fishing survey; yield per unit area; biomass; tailings dam.

  4. Room-Temperature Growth of SiC Thin Films by Dual-Ion-Beam Sputtering Deposition

    Directory of Open Access Journals (Sweden)

    C. G. Jin

    2008-01-01

    Full Text Available Silicon carbide (SiC films were prepared by single and dual-ion-beamsputtering deposition at room temperature. An assisted Ar+ ion beam (ion energy Ei = 150 eV was directed to bombard the substrate surface to be helpful for forming SiC films. The microstructure and optical properties of nonirradicated and assisted ion-beam irradicated films have been characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, and Raman spectra. TEM result shows that the films are amorphous. The films exposed to a low-energy assisted ion-beam irradicated during sputtering from a-SiC target have exhibited smoother and compacter surface topography than which deposited with nonirradicated. The ion-beam irradicated improves the adhesion between film and substrate and releases the stress between film and substrate. With assisted ion-beam irradicated, the density of the Si–C bond in the film has increased. At the same time, the excess C atoms or the size of the sp2 bonded clusters reduces, and the a-Si phase decreases. These results indicate that the composition of the film is mainly Si–C bond.

  5. Growth and characterization of yttrium iron garnet films on Si substrates by Chemical Solution Deposition (CSD) technique

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xin; Chen, Ying; Wang, Genshui [Key Laboratory of Inorganic Function Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 1295 Dingxi Rd., Shanghai 200050 (China); Zhang, Yuanyuan [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Ge, Jun [Key Laboratory of Inorganic Function Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 1295 Dingxi Rd., Shanghai 200050 (China); Tang, Xiaodong [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Ponchel, Freddy; Rémiens, Denis [Institute of Electronics, Microelectronics and Nanotechnology (IEMN)–DOAE, UMR CNRS 8520, Université des Sciences et Technologies de Lille, 59652 Villeneuve d’Ascq Cedex (France); Dong, Xianlin, E-mail: xldong@mail.sic.ac.cn [Key Laboratory of Inorganic Function Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 1295 Dingxi Rd., Shanghai 200050 (China)

    2016-06-25

    Yttrium Iron Garnet (YIG) films were prepared on Si substrates by Chemical Solution Deposition (CSD) technique using acetic acid and deionized water as solvents. Well-crystallized and crack-free YIG films were obtained when annealed at 750 °C and 850 °C respectively, showing a low surface roughness of several nanometers. When annealed at 750 °C for 30 min, the saturated magnetization (Ms) and coercive field (Hc) of YIG films were 0.121 emu/mm{sup 3} (4πMs = 1.52 kGs) and 7 Oe respectively, which were similar to that prepared by PLD technique. The peak-to-peak linewidth of ferromagnetic resonance (FMR) was 220 Oe at 9.10 GHz. The results demonstrated that CSD was an excellent technique to prepare high quality yttrium iron garnet (YIG) films on silicon, which could provide a lower-cost way for large-scale production on Si-based integrated devices. - Highlights: • The preparation of YIG films by Chemical Solution Deposition are demonstrated. • Well-crystallized and crack-free YIG films can be obtained on Si substrate by CSD. • YIG films can be crystallized in 750 °C with good magnetic performances. • It's beneficial to large-scale production of YIG films on Si integrated devices.

  6. Low-temperature growth of highly crystallized transparent conductive fluorine-doped tin oxide films by intermittent spray pyrolysis deposition

    Energy Technology Data Exchange (ETDEWEB)

    Fukano, Tatsuo; Motohiro, Tomoyoshi [Toyota Central Research and Development Laboratories Inc., Nagakute, Aichi 480-1192 (Japan)

    2004-05-30

    Following the procedure by Sawada et al. (Thin Solid Films 409 (2002) 46), high-quality SnO{sub 2}:F films were grown on glass substrates at relatively low temperatures of 325-340C by intermittent spray pyrolysis deposition using a perfume atomizer for cosmetics use. Even though the substrate temperature is low, as-deposited films show a high optical transmittance of 92% in the visible range, a low electric resistivity of 5.8x10{sup -4}{omega}cm and a high Hall mobility of 28cm{sup 2}/Vs. The F/Sn atomic ratio (0.0074) in the films is low in comparison with the value (0.5) in the sprayed solution. The carrier density in the film is approximately equal to the F-ion density, suggesting that most of the F-ions effectively function as active dopants. Films' transmittance and resistivity show little change after a 450C 60min heat treatment in the atmosphere, evidencing a high heat resistance. The SnO{sub 2}:F films obtained in this work remove the difficulty to improve the figure of merit at low synthesis temperatures.

  7. Epitaxial Growth of MgxCa1-xO on GaN by Atomic Layer Deposition.

    Science.gov (United States)

    Lou, Xiabing; Zhou, Hong; Kim, Sang Bok; Alghamdi, Sami; Gong, Xian; Feng, Jun; Wang, Xinwei; Ye, Peide D; Gordon, Roy G

    2016-12-14

    We demonstrate for the first time that a single-crystalline epitaxial Mg x Ca 1-x O film can be deposited on gallium nitride (GaN) by atomic layer deposition (ALD). By adjusting the ratio between the amounts of Mg and Ca in the film, a lattice matched Mg x Ca 1-x O/GaN(0001) interface can be achieved with low interfacial defect density. High-resolution X-ray diffraction (XRD) shows that the lattice parameter of this ternary oxide nearly obeys Vegard's law. An atomically sharp interface from cross-sectional transmission electron microscopy (TEM) confirmed the high quality of the epitaxy. High-temperature capacitance-voltage characterization showed that the film with composition Mg 0.25 Ca 0.75 O has the lowest interfacial defect density. With this optimal oxide composition, a Mg 0.25 Ca 0.75 O/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility (MOS-HEMT) device was fabricated. An ultrahigh on/off ratio of 10 12 and a near ideal SS of 62 mV/dec were achieved with this device.

  8. The impacts of growth temperature on morphologies, compositions and optical properties of Mg-doped ZnO nanomaterials by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.H., E-mail: wangxh@sdju.edu.cn [School of Mechanical Engineering, Shanghai Dianji University, 1201 Jiang Chuan Road, Shanghai 200245 (China); Huang, L.Q.; Niu, L.J.; Li, R.B. [School of Mechanical Engineering, Shanghai Dianji University, 1201 Jiang Chuan Road, Shanghai 200245 (China); Fan, D.H. [Institute of Functional Materials Research, Department of Mathematics and Physics, Wuyi University, Jiangmen 529020 (China); Zhang, F.B.; Chen, Z.W.; Wang, X.; Guo, Q.X. [Department of Electrical and Electronic Engineering, Synchrotron Light Application Center, Saga University, Saga 840-8502 (Japan)

    2015-02-15

    Highlights: • Mg-doped ZnO nanomaterials were fabricated by chemical vapor deposition (CVD). • Growth temperature determines the characteristics of Zn{sub 1-x}Mg{sub x}O nanomaterials. • The modulation of band gap is caused by Mg addition. - Abstract: The Mg-doped ZnO (Zn{sub 1-x}Mg{sub x}O) nanomaterials with different morphologies of nanoparticles, partially opened nanowire-on-spherical shells, hemispheric shells and chain-like nanoparticles were synthesized at 750, 850, 900 and 1000 °C by a simple chemical vapor deposition. The energy dispersive X-ray (EDX) measurements indicate that Mg content increases from 2.87 at.% to 5.01 at.% with the increase of growth temperature from 750 to 1000 °C. The measurement results of X-ray diffraction (XRD) show that the (0 0 2) peaks of Zn{sub 1-x}Mg{sub x}O nanomaterials shift to higher diffraction angle with the increase of Mg content, implying that Mg{sup 2+} is substituted into Zn{sup 2+} site. The absorption spectra at room temperature exhibit that the band gap of the Mg-doped ZnO nanomaterials increases with the Mg concentration, illustrating that the modulation of band gap is caused by Mg addition. The PL measurements show that UV peak from Zn{sub 1-x}Mg{sub x}O nanomaterials is shifted towards lower wavelength side (blue shift) from 381 nm to 372 nm with the increase of the Mg dopant content. The room-temperature Raman spectra show that the crystal quality of the Zn{sub 1-x}Mg{sub x}O nanomaterials is improved with the increase of growth temperature, and the Mg dopants do not decrease the crystal quality of ZnO nanomaterials.

  9. URBANIZATION EFFECTS ON TREE GROWTH IN THE VICINITY OF NEW YORK CITY

    Science.gov (United States)

    Plants in urban ecosystems are exposed to many pollutants and higher temperatures, CO2 and nitrogen deposition than plants in rural areas. Although each factor has a detrimental or beneficial influence on plant growth, the net effect of all factors and the key driving variables a...

  10. PhysioNet

    Data.gov (United States)

    U.S. Department of Health & Human Services — The PhysioNet Resource is intended to stimulate current research and new investigations in the study of complex biomedical and physiologic signals. It offers free...

  11. NetSig

    DEFF Research Database (Denmark)

    Horn, Heiko; Lawrence, Michael S; Chouinard, Candace R

    2018-01-01

    Methods that integrate molecular network information and tumor genome data could complement gene-based statistical tests to identify likely new cancer genes; but such approaches are challenging to validate at scale, and their predictive value remains unclear. We developed a robust statistic (Net......Sig) that integrates protein interaction networks with data from 4,742 tumor exomes. NetSig can accurately classify known driver genes in 60% of tested tumor types and predicts 62 new driver candidates. Using a quantitative experimental framework to determine in vivo tumorigenic potential in mice, we found that Net......Sig candidates induce tumors at rates that are comparable to those of known oncogenes and are ten-fold higher than those of random genes. By reanalyzing nine tumor-inducing NetSig candidates in 242 patients with oncogene-negative lung adenocarcinomas, we find that two (AKT2 and TFDP2) are significantly amplified...

  12. Blanket testing in NET

    International Nuclear Information System (INIS)

    Chazalon, M.; Daenner, W.; Libin, B.

    1989-01-01

    The testing stages in NET for the performance assessment of the various breeding blanket concepts developed at the present time in Europe for DEMO (LiPb and ceramic blankets) and the requirements upon NET to perform these tests are reviewed. Typical locations available in NET for blanket testing are the central outboard segments and the horizontal ports of in-vessel sectors. These test positions will be connectable with external test loops. The number of test loops (helium, water, liquid metal) will be such that each major class of blankets can be tested in NET. The test positions, the boundary conditions and the external test loops are identified and the requirements for test blankets are summarized (author). 6

  13. Programming NET 35

    CERN Document Server

    Liberty, Jesse

    2009-01-01

    Bestselling author Jesse Liberty and industry expert Alex Horovitz uncover the common threads that unite the .NET 3.5 technologies, so you can benefit from the best practices and architectural patterns baked into the new Microsoft frameworks. The book offers a Grand Tour" of .NET 3.5 that describes how the principal technologies can be used together, with Ajax, to build modern n-tier and service-oriented applications. "

  14. NET SALARY ADJUSTMENT

    CERN Multimedia

    Finance Division

    2001-01-01

    On 15 June 2001 the Council approved the correction of the discrepancy identified in the net salary adjustment implemented on 1st January 2001 by retroactively increasing the scale of basic salaries to achieve the 2.8% average net salary adjustment approved in December 2000. We should like to inform you that the corresponding adjustment will be made to your July salary. Full details of the retroactive adjustments will consequently be shown on your pay slip.

  15. Growth and properties of SrBi2TaNbO9 ferroelectric thin films using pulsed laser deposition

    International Nuclear Information System (INIS)

    Yang Pingxiong; Deng Hongmei; Shi Meirong; Tong Ziyang; Qin Sumei

    2007-01-01

    High quality SrBi 2 TaNbO 9 (SBTN) ferroelectric thin films were fabricated on platinized silicon by pulsed laser deposition. Microstructure and ferroelectric properties of the films were characterized. Optical fatigue (light/bias) for the thin films was studied and the average remanent polarization dropped by nearly 55% due to the bias/illumination treatment. Optical properties of the thin films were studied by spectroscopic ellipsometry (SE) from the ultraviolet to the infrared region. Optical constants, n ∼ 0.16 in the infrared region and n ∼ 2.12 in the visible spectral region, were determined through refractive index functions. The band gap energy is estimated to be 3.93 eV

  16. Effects of acidic deposition on nutrient uptake, nutrient cycling and growth processes of vegetation in the spruce-fir ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, S.B.; Garten, C.T.; Wullschleger, S.D. [Oak Ridge National Lab., TN (United States)] [and others

    1996-10-16

    This report summarizes progress in three years of field research designed to evaluate biological and chemical indicators of the current and future health of the Southern Appalachian spruce-fir ecosystem. The emphasis of this research has been on the identification and understanding of mechanisms through which current levels of acidic deposition are impacting ecosystem processes. The identification of these principal mechanisms and key biological indicators of change was designed to improve our capabilities to detect, monitor, and assess the effects of air quality regulations and attendant future air quality changes on ecosystem response. Individual research tasks focused on the following research areas: (1) the significance of foliar uptake of atmospheric sources of nitrogen in relationship to plant utilization of N from available soil reserves; (2) linkages between atmospheric inputs to the soil surface, solution chemistry, and decomposition in the upper organic soil horizons; (3) effects of soil solution chemistry on uptake of cations and aluminum by fine roots; and (4) the effects of varying rates of calcium supply on carbon metabolism of Fraser fir and red spruce, and the relationship between calcium levels in wood cells and integrity of wood formed in bole and branches. Each of the individual tasks was designed to focus upon a mechanism or process that we consider critical to understanding chemical and biological linkages. These linkages will be important determinants in understanding the basis of past and potential future responses of the high elevation Southern Appalachian Forest to acidic deposition and other co-occurring environmental stresses. This report contains (1) background and rationale for the research undertaken in 1992-94; (2) a summary of principal research findings; (3) publications from this research; and (4) characterization of data sets produced by this research which will be the basis of future research, analyses and/or publications.

  17. Spontaneous growth of whiskers from an interlayer of Mo sub 2 C beneath a diamond particle deposited in a combustion-flame

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Katsuyuki; Komatsu, Shojiro; Ishigaki, Takamasa; Matsumoto, Seiichiro; Moriyoshi, Yusuke (National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (Japan))

    1992-02-01

    When diamond particles deposited on a molybdenum substrate in a C{sub 2}H{sub -}O{sub 2} combustion-flame were kept for one year in the ambient atmosphere at room temperature, spontaneous whisker growth from an interlayer of Mo{sub 2}C beneath the diamond particles took place. The whiskers were clarified by electron probe micro-analysis (EPMA) and transmission electron microscopy (TEM) in a polycrystal composed of MoO{sub 2}, MoOC, and Mo{sub 2}C. The growth mechanism of them is discussed from two different points of view as follows: One is that the oxidation of an interlayer of Mo{sub 2}C beneath a diamond particle effectively reduces the surface free energy between the interlayer and diamond particle; consequently, the whisker can grow by using a screw dislocation. The other is that the internal stress existing between a diamond particle and an Mo{sub 2}C interlayer provides a very reactive zone where the growth of whisker takes place through the oxidation of Mo{sub 2}C. (orig.).

  18. 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

  19. Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas y Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F.; Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati (Roma) (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-02-26

    A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

  20. Effects of copper precursor concentration on the growth of cupric oxide nanorods for photoelectrode using a modified chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Hee-bong [Department of Nano Science and Engineering, High Safety Vehicle Core Technology Research Center, Inje University, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, Hyukhyun, E-mail: hhryu@inje.ac.kr [Department of Nano Science and Engineering, High Safety Vehicle Core Technology Research Center, Inje University, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Lee, Won-Jae [Department of Materials and Components Engineering, Dong-Eui University, Busan 614-714 (Korea, Republic of)

    2015-01-25

    Highlights: • CuO nanorod photoelectrodes were prepared by modified CBD method. • The CuO nanorods were vertically grown with a high growth rate. • Effects of precursor concentration on the CuO nanorods were investigated. - Abstract: In this study, vertically aligned CuO nanorods were grown using a modified chemical bath deposition method with various copper precursor concentrations. The morphological, structural, optical and photoelectrochemical properties of the synthesized CuO samples were characterized using a field-emission scanning electron microscope, an X-ray diffractometer, a UV–visible spectrometer and a three-electrode potentiostat, respectively. The growth rates of the samples varied from 4.3 to 500 nm/min with the varying precursor concentrations. The vertically well-grown CuO nanorods exhibited one-dimensional growth along the (0 2 0) plane. We obtained a maximum photocurrent density of −1.05 mA/cm{sup 2} at −0.6 V (vs. SCE) from the CuO nanorod photoelectrode grown using the 10 mM copper precursor concentration.

  1. CH3NH3PbI3 grain growth and interfacial properties in meso-structured perovskite solar cells fabricated by two-step deposition

    Science.gov (United States)

    Yao, Zhibo; Wang, Wenli; Shen, Heping; Zhang, Ye; Luo, Qiang; Yin, Xuewen; Dai, Xuezeng; Li, Jianbao; Lin, Hong

    2017-12-01

    Although the two-step deposition (TSD) method is widely adopted for the high performance perovskite solar cells (PSCs), the CH3NH3PbI3 perovskite crystal growth mechanism during the TSD process and the photo-generated charge recombination dynamics in the mesoporous-TiO2 (mp-TiO2)/CH3NH3PbI3/hole transporting material (HTM) system remains unexploited. Herein, we modified the concentration of PbI2 (C(PbI2)) solution to control the perovskite crystal properties, and observed an abnormal CH3NH3PbI3 grain growth phenomenon atop mesoporous TiO2 film. To illustrate this abnormal grain growth mechanism, we propose that a grain ripening process is taking place during the transformation from PbI2 to CH3NH3PbI3, and discuss the PbI2 nuclei morphology, perovskite grain growing stage, as well as Pb:I atomic ratio difference among CH3NH3PbI3 grains with different morphology. These C(PbI2)-dependent perovskite morphologies resulted in varied charge carrier transfer properties throughout the mp-TiO2/CH3NH3PbI3/HTM hybrid, as illustrated by photoluminescence measurement. Furthermore, the effect of CH3NH3PbI3 morphology on light absorption and interfacial properties is investigated and correlated with the photovoltaic performance of PSCs.

  2. The role of catalytic nanoparticle pretreatment on the growth of vertically aligned carbon nanotubes by hot-filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Hwan; Gohier, Aurélien; Bourée, Jean Eric; Châtelet, Marc; Cojocaru, Costel-Sorin, E-mail: costel-sorin.cojocaru@polytechnique.edu

    2015-01-30

    The effect of atomic hydrogen assisted pre-treatment on the growth of vertically aligned carbon nanotubes using hot-filament chemical vapor deposition was investigated. Iron nanoparticle catalysts were formed on an aluminum oxide support layer by spraying of iron chloride salt solutions as catalyst precursor. It is found that pre-treatment time and process temperature tune the density as well as the shape and the structure of the grown carbon nanotubes. An optimum pre-treatment time can be found for the growth of long and well aligned carbon nanotubes, densely packed to each other. To provide insight on this behavior, the iron catalytic nanoparticles formed after the atomic hydrogen assisted pre-treatment were analyzed by atomic force microscopy. The relations between the size and the density of the as-formed catalyst and the as-grown carbon nanotube's structure and density are discussed. - Highlights: • Effect of the atomic hydrogen assisted pre-treatment on the growth of VACNT using hot-filament CVD. • Pre-treatment time and process temperature tune the density, the shape and the structure of the CNTs. • Correlations between size and density of the as-formed catalyst and the CNT’s structure and density. • Carbon nanotubes synthesized at low temperature down to 500 °C using spayed iron chloride salts. • Density of the CNT carpet adjusted by catalytic nanoparticle engineering.

  3. Chemical vapor deposition growth of carbon nanotubes on Si substrates using Fe catalyst: What happens at the nanotube/Fe/Si interface

    International Nuclear Information System (INIS)

    Chakraborty, Amit K.; Jacobs, J.; Anderson, C.; Roberts, C. J.; Hunt, Michael R. C.

    2006-01-01

    Direct growth of carbon nanotubes (CNTs) on silicon is of great importance for their potential exploitation in the semiconductor industry. In this article we investigate the chemical vapor deposition growth of CNTs on Si substrates from ethylene precursor using an iron catalyst. We observe that CNTs are produced only at temperatures between 830 and 980 deg. C, and within this narrow temperature window CNT yield initially increases with temperature to reach a maximum around 900 deg. C and then declines. While the requirement of a minimum temperature to initiate CNT growth can be understood by considering the minimum energy necessary to activate the catalyst particles, characterization of the as-grown CNTs by atomic force microscopy and x-ray photoelectron spectroscopy reveals that a loss of catalyst is responsible for the observed decline in CNT yield above 900 deg. C. However, unlike some previous reports suggesting surface silicide formation as the mechanism for catalyst loss, we find that either subsurface diffusion or evaporation is the mechanism for the loss of catalyst material in the current study

  4. Assessing the Roles of Iron, Macronutrients and Wet deposition in Controlling Phytoplankton Growth in Seasonally Oligotrophic Waters of the Mid-Atlantic Bight

    Science.gov (United States)

    Sedwick, P.; Mulholland, M. R.; Najjar, R.; Bernhardt, P. W.; Price, L. M.; Sohst, B. M.; Sookhdeo, C.; Widner, B.

    2016-02-01

    The role of iron supply in regulating phytoplankton production in high-nutrient, low-chlorophyll ocean regions has been well established. Less clear, however, is the importance of iron for phytoplankton processes in other oceanic settings, such as coastal and oligotrophic waters, where differential changes in the supply and removal of dissolved iron (dFe) can result in limitation or co-limitation of growth due to iron deficiency. One such region of interest is the Mid-Atlantic Bight (MAB), where previous field experiments have provided some evidence of co-limitation of algal growth by nitrogen and iron. In summer 2014 we conducted field sampling and shipboard experiments to assess the role of iron and macronutrient availability in controlling primary production in seasonally oligotrophic waters over the MAB continental slope, with a focus on the the impacts of wet deposition. Our results indicate that nitrogen was the proximate limiting nutrient, with a secondary limitation imposed by availability of phosphorus; we found no evidence for a deficiency in dFe, which was present at concentrations in the range 0.3-0.9 nM. Phytoplankton growth was clearly stimulated by the addition of natural rainwater, suggesting that summer rain events stimulate primary production in the MAB by contributing new nitrogen (primarily as ammonium) and phosphorus, whilst maintaining iron-replete conditions.

  5. Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures.

    Science.gov (United States)

    Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

    2015-11-13

    2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices.

  6. Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

    International Nuclear Information System (INIS)

    Conde, J.C.; Martin, E.; Gontad, F.; Chiussi, S.; Fornarini, L.; Leon, B.

    2010-01-01

    A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

  7. Size-controlled growth of ZnO nanowires by catalyst-free high-pressure pulsed laser deposition and their optical properties

    Directory of Open Access Journals (Sweden)

    W. Z. Liu

    2011-06-01

    Full Text Available Single crystalline ZnO nanowires were fabricated on Si (100 substrates by catalyst-free high-pressure pulsed laser deposition. It is found that the nanowires start to form when the substrate temperature and growth pressure exceed the critical values of 700 oC and 700 Pa, and their size strongly depends on these growth conditions. That is, the aspect ratio of the nanowires decreases with increasing temperature or decreasing pressure. Such a size dependence on growth conditions was discussed in terms of surface migration and scattering of ablated atoms. Room-temperature photoluminescence spectrum of ZnO nanowires shows a dominant near-band-edge emission peak at 3.28 eV and a visible emission band centered at 2.39 eV. Temperature-dependent photoluminescence studies reveal that the former consists of the acceptor-bound exciton and free exciton emissions; while the latter varies in intensity with the aspect ratio of the nanowires and is attributed to the surface-mediated deep level emission.

  8. Thermal and optical properties of polycrystalline CdS thin films deposited by the gradient recrystallization and growth (GREG) technique using photoacoustic methods

    International Nuclear Information System (INIS)

    Albor-Aguilera, M.L.; Gonzalez-Trujillo, M.A.; Cruz-Orea, A.; Tufino-Velazquez, M.

    2009-01-01

    In this work we report the study of the thermal and optical properties of polycrystalline CdS thin films deposited by the gradient recrystallization and growth technique. CdS films were grown on pyrex glass substrates. These studies were carried out using an open photoacoustic cell made out of an electret microphone. From X-ray diffraction, atomic force microscope and photoluminescence measurements we observed polycrystalline CdS films with good morphology and crystalline quality. We obtained a thermal diffusivity coefficient of our samples with values ranging from 3.15 to 3.89 x 10 -2 cm 2 /s. For comparison, we measured a value of 1.0 x 10 -2 cm 2 /s for the thermal diffusivity coefficient of a CdS single crystal. We measured an energy gap value of 2.42 eV for our samples by using a photoacoustic spectroscopy system

  9. Propagation characteristic of THz wave in camouflage net material

    Science.gov (United States)

    Dong, Hailong; Wang, Jiachun; Chen, Zongsheng; Lin, Zhidan; Zhao, Dapeng; Liu, Ruihuang

    2017-10-01

    Terahertz (THz) radar system, with excellent potentials such as high-resolution and strong penetration capability, is promising in the field of anti-camouflage. Camouflage net is processed by cutting the camouflage net material, which is fabricated on pre-processing substrate by depositing coatings with camouflage abilities in different bands, such as visible, infrared and radar. In this paper, we concentrate on the propagation characteristic of THz wave in camouflage net material. Firstly, function and structure of camouflage net were analyzed. Then the advantage and appliance of terahertz time-domain spectroscopy (THz-TDS) was introduced. And the relevant experiments were conducted by utilizing THz-TDS. The results obtained indicate that THz wave has better penetration capacity in camouflage net material, which demonstrates the feasibility of using THz radar to detect those targets covered with camouflage net.

  10. Graphene synthesis by laser-assisted chemical vapor deposition on Ni plate and the effect of process parameters on uniform graphene growth

    International Nuclear Information System (INIS)

    Jiang, Juan; Lin, Zhe; Ye, Xiaohui; Zhong, Minlin; Huang, Ting; Zhu, Hongwei

    2014-01-01

    A fast, simple technique was developed to fabricate few-layer graphene films at ambient pressure and room temperature by laser-assisted chemical vapor deposition on polycrystalline Ni plates. Laser scanning speed was found as the most important factor in the production of few-layer graphene. The quality of graphene films was controlled by varying the laser power. Uniform graphene ribbons with a width of 1.5 mm and a length of 16 mm were obtained at a scanning speed of 1.3 mm/s and a laser power of 600 W. The developed technique provided a promising application of a high-power laser system to fabricate a graphene film. - Highlights: • Uniform few-layer graphene was fabricated at room temperature and ambient conditions. • Laser-assisted chemical vapor deposition was used to grow the layers in a few seconds. • The effect of process parameters on graphene growth was discussed. • This cost effective method could facilitate the integration of graphene in electronic devices

  11. Growth and process identification of CuInS 2 on GaP by chemical vapor deposition

    Science.gov (United States)

    Hwang, H. L.; Sun, C. Y.; Fang, C. S.; Chang, S. D.; Cheng, C. H.; Yang, M. H.; Lin, H. H.; Tuwan-Mu, H.

    1981-10-01

    Experimental techniques for growing CuInS 2 layers on GaP substrates by the metalorganic method have been developed. Hydrogen sulfide gas together with the vapors of CuCl( NCCH3) n and InCl3( NCCH3) both of which were generated by bubbling nitrogen through sources, using a solvent of acetonitride, were used as transport agents. Various characterization techniques such as atomic absorption (AA), neutron activation analysis (NAA), energy dispersive analysis by X-rays (EDAX), Rutherford back-scattering analysis (RBS), and X-ray analyses were used to help understand the fundamental mechanism of the CVD growth.

  12. TiO2 coatings via atomic layer deposition on polyurethane and polydimethylsiloxane substrates: Properties and effects on C. albicans growth and inactivation process

    Science.gov (United States)

    Pessoa, R. S.; dos Santos, V. P.; Cardoso, S. B.; Doria, A. C. O. C.; Figueira, F. R.; Rodrigues, B. V. M.; Testoni, G. E.; Fraga, M. A.; Marciano, F. R.; Lobo, A. O.; Maciel, H. S.

    2017-11-01

    Atomic layer deposition (ALD) surges as an attractive technology to deposit thin films on different substrates for many advanced biomedical applications. Herein titanium dioxide (TiO2) thin films were successful obtained on polyurethane (PU) and polydimethylsiloxane (PDMS) substrates using ALD. The effect of TiO2 films on Candida albicans growth and inactivation process were also systematic discussed. TiCl4 and H2O were used as precursors at 80 °C, while the reaction cycle number ranged from 500 to 2000. Several chemical, physical and physicochemical techniques were used to evaluate the growth kinetics, elemental composition, material structure, chemical bonds, contact angle, work of adhesion and surface morphology of the ALD TiO2 thin films grown on both substrates. For microbiological analyses, yeasts of standard strains of C. albicans were grown on non- and TiO2-coated substrates. Next, the antifungal and photocatalytic activities of the TiO2 were also investigated by counting the colony-forming units (CFU) before and after UV-light treatment. Chlorine-doped amorphous TiO2 films with varied thicknesses and Cl concentration ranging from 2 to 12% were obtained. In sum, the ALD TiO2 films suppressed the yeast-hyphal transition of C. albicans onto PU, however, a high adhesion of yeasts was observed. Conversely, for PDMS substrate, the yeast adhesion did not change, as observed in control. Comparatively to control, the TiO2-covered PDMS had a reduction in CFU up to 59.5% after UV treatment, while no modification was observed to TiO2-covered PU. These results pointed out that ALD chlorine-doped amorphous TiO2 films grown on biomedical polymeric surfaces may act as fungistatic materials. Furthermore, in case of contamination, these materials may also behave as antifungal materials under UV light exposure.

  13. Inclusive Growth: More than Safety Nets

    International Development Research Centre (IDRC) Digital Library (Canada)

    IDRC CRDI

    objective of the Indian Congress Party-led government since 2004, ... have in common is that they have had stable and often high rates of ... continued threat of economic instability, but also because more is needed than the sustained.

  14. Epitaxial growth of SrTiO3/YBa2Cu3O7 - x heterostructures by plasma-enhanced metalorganic chemical vapor deposition

    Science.gov (United States)

    Liang, S.; Chern, C. S.; Shi, Z. Q.; Lu, P.; Safari, A.; Lu, Y.; Kear, B. H.; Hou, S. Y.

    1994-06-01

    We report heteroepitaxial growth of SrTiO3 on YBa2Cu3O7-x/LaAlO3 substrates by plasma-enhanced metalorganic chemical vapor deposition. X-ray diffraction results indicated that SrTiO3 films were epitaxially grown on a (001) YBa2Cu3O7-x surface with [100] orientation perpendicular to the surface. The film composition, with Sr/Ti molar ratio in the range of 0.9 to 1.1, was determined by Rutherford backscattering spectrometry and energy dispersive spectroscopy. The thickness of the SrTiO3 films is 0.1-0.2 μm. The epitaxial growth was further evidenced by high-resolution transmission electron microscopy and selected area diffraction. Atomically abrupt SrTiO3/YBa2Cu3O7-x interface and epitaxial growth with [100]SrTiO3∥[001]YBa2Cu3O7-x were observed in this study. The superconducting transition temperature of the bottom YBa2Cu3O7-x layer, as measured by ac susceptometer, did not significantly degrade after the growth of overlayer SrTiO3. The capacitance-voltage measurements showed that the dielectric constant of the SrTiO3 films was as high as 315 at a signal frequency of 100 KHz. The leakage current density through the SrTiO3 films is about 1×10-6 A/cm2 at 2-V operation. Data analysis on the current-voltage characteristic indicated that the conduction process is related to bulk-limited Poole-Frenkel emission.

  15. Fast Growth of GaN Epilayers via Laser-Assisted Metal-Organic Chemical Vapor Deposition for Ultraviolet Photodetector Applications.

    Science.gov (United States)

    Rabiee Golgir, Hossein; Li, Da Wei; Keramatnejad, Kamran; Zou, Qi Ming; Xiao, Jun; Wang, Fei; Jiang, Lan; Silvain, Jean-François; Lu, Yong Feng

    2017-06-28

    In this study, we successfully developed a carbon dioxide (CO 2 )-laser-assisted metal-organic chemical vapor deposition (LMOCVD) approach to fast synthesis of high-quality gallium nitride (GaN) epilayers on Al 2 O 3 [sapphire(0001)] substrates. By employing a two-step growth procedure, high crystallinity and smooth GaN epilayers with a fast growth rate of 25.8 μm/h were obtained. The high crystallinity was confirmed by a combination of techniques, including X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and atomic force microscopy. By optimizing growth parameters, the ∼4.3-μm-thick GaN films grown at 990 °C for 10 min showed a smooth surface with a root-mean-square surface roughness of ∼1.9 nm and excellent thickness uniformity with sharp GaN/substrate interfaces. The full-width at half-maximum values of the GaN(0002) X-ray rocking curve of 313 arcsec and the GaN(101̅2) X-ray rocking curve of 390 arcsec further confirmed the high crystallinity of the GaN epilayers. We also fabricated ultraviolet (UV) photodetectors based on the as-grown GaN layers, which exhibited a high responsivity of 0.108 A W -1 at 367 nm and a fast response time of ∼125 ns, demonstrating its high optical quality with potential in optoelectronic applications. Our strategy thus provides a simple and cost-effective means toward fast and high-quality GaN heteroepitaxy growth suitable for fabricating high-performance GaN-based UV detectors.

  16. Chemical Vapor Deposition Growth of Degenerate p-Type Mo-Doped ReS2 Films and Their Homojunction.

    Science.gov (United States)

    Qin, Jing-Kai; Shao, Wen-Zhu; Xu, Cheng-Yan; Li, Yang; Ren, Dan-Dan; Song, Xiao-Guo; Zhen, Liang

    2017-05-10

    Substitutional doping of transition metal dichalcogenide two-dimensional materials has proven to be effective in tuning their intrinsic properties, such as band gap, transport characteristics, and magnetism. In this study, we realized substitutional doping of monolayer rhenium disulfide (ReS 2 ) with Mo via chemical vapor deposition. Scanning transmission electron microscopy demonstrated that Mo atoms are successfully doped into ReS 2 by substitutionally replacing Re atoms in the lattice. Electrical measurements revealed the degenerate p-type semiconductor behavior of Mo-doped ReS 2 field effect transistors, in agreement with density functional theory calculations. The p-n diode device based on a doped ReS 2 and ReS 2 homojunction exhibited gate-tunable current rectification behaviors, and the maximum rectification ratio could reach up to 150 at V d = -2/+2 V. The successful synthesis of p-type ReS 2 in this study could largely promote its application in novel electronic and optoelectronic devices.

  17. Growth of CdS thin films on indium coated glass substrates via chemical bath deposition and subsequent air annealing

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Biswajit; Kumar, Kamlesh; Singh, Balwant Kr; Banerjee, Pushan; Das, Subrata, E-mail: neillohit@yahoo.co.in

    2014-11-30

    Graphical abstract: - Highlights: • CdS film grown on indium coated glass substrates via CBD and subsequent annealing. • Disappearance of the indium (1 1 2) peak confirms interdiffusion at 300 °C. • SIMS indicates the subsequent interdiffusion at progressively higher temperature. • Composite In–CdS layer showed lower photosensitivity compared to pure CdS. - Abstract: In the present work attempts were made to synthesize indium doped CdS films by fabricating In/CdS bilayers using CBD-CdS on vacuum evaporated In thin films and subsequent air annealing. 135 nm CdS films were grown onto 20 nm and 35 nm indium coated glass substrate employing chemical bath deposition technique. The In/CdS bilayers thus formed were subjected to heat treatment at the temperatures between 200 and 400 °C for 4 min in the muffle furnace to facilitate indium to diffuse into the CdS films. XRD pattern ascertained no noticeable shift in lattice constant implying grain boundary metal segregation, while secondary ion mass spectrometry indicated the diffusion profile of indium into CdS matrices. Mass spectrometry results showed that substantial diffusion of indium had been taken place within CdS at 400 °C. Dark and photocurrent with different illumination time were measured to ascertain the photosensitivity of pure and composite CdS films.

  18. Growth and characterization of nitrogen-doped TiO2 thin films prepared by reactive pulsed laser deposition

    International Nuclear Information System (INIS)

    Sauthier, G.; Ferrer, F.J.; Figueras, A.; Gyoergy, E.

    2010-01-01

    Nitrogen-doped titanium dioxide (TiO 2 ) thin films were grown on (001) SiO 2 substrates by reactive pulsed laser deposition. A KrF* excimer laser source (λ = 248 nm, τ FWHM ≅ 10 ns, ν = 10 Hz) was used for the irradiations of pressed powder targets composed by both anatase and rutile phase TiO 2 . The experiments were performed in a controlled reactive atmosphere consisting of oxygen or mixtures of oxygen and nitrogen gases. The obtained thin film crystal structure was investigated by X-ray diffraction, while their chemical composition as well as chemical bonding states between the elements were studied by X-ray photoelectron spectroscopy. An interrelation was found between nitrogen concentration, crystalline structure, bonding states between the elements, and the formation of titanium oxinitride compounds. Moreover, as a result of the nitrogen incorporation in the films a continuous red-shift of the optical absorption edge accompanied by absorption in the visible spectral range between 400 and 500 nm wavelength was observed.

  19. Selenium-assisted controlled growth of graphene–Bi_2Se_3 nanoplates hybrid Dirac materials by chemical vapor deposition

    International Nuclear Information System (INIS)

    Sun, Zhencui; Man, Baoyuan; Yang, Cheng; Liu, Mei; Jiang, Shouzhen; Zhang, Chao; Zhang, Jiaxin; Liu, Fuyan; Xu, Yuanyuan

    2016-01-01

    Graphical abstract: - Highlights: • We synthesize the graphene–Bi_2Se_3 nanoplates hybrid Dirac materials via CVD. • The Se seed layer impels the Bi_2Se_3 plates growing along the lateral direction. • The Se seed layer can supply enough Se atoms to fill the Se vacancies. • The Se seed layer can effectively avoid the interaction of Bi_2Se_3 and the graphene. • The Se seed layer can be used to control the density of the Bi_2Se_3 nanoplates. - Abstract: Se seed layers were used to synthesize the high-quality graphene–Bi_2Se_3 nanoplates hybrid Dirac materials via chemical vapor deposition (CVD) method. The morphology, crystallization and structural properties of the hybrid Dirac materials were characterized by SEM, EDS, Raman, XRD, AFM and HRTEM. The measurement results verify that the Se seed layer on the graphene surface can effectively saturate the surface dangling bonds of the graphene, which not only impel the uniform Bi_2Se_3 nanoplates growing along the horizontal direction but also can supply enough Se atoms to fill the Se vacancies. We also demonstrate the Se seed layer can effectively avoid the interaction of Bi_2Se_3 and the graphene. Further experiments testify the different Se seed layer on the graphene surface can be used to control the density of the Bi_2Se_3 nanoplates.

  20. Industrial metalorganic chemical vapor deposition technology for the growth of YBa2Cu3O7-∂

    International Nuclear Information System (INIS)

    Schulte, B.; Richards, B.C.; Cook, S.L.

    1997-01-01

    MOCVD is the established technology for the mass production of compound semiconductors for e.g. opto-electronic devices. To transfer the MOCVD technology for HTS films to the standard MOCVD technology used in semiconductor production two major challenges have to be solved: 1. the Ba-precursor instability and 2. the demonstration of uniform deposition of HTS films onto large area substrates. This paper presents an industrial MOCVD process solving these challenges using a new stable fluorinated Ba-precursor and a gas foil rotation trademark susceptor. On a 2 inch diameter substrate area state-of-the-art YBCO thin films were fabricated having a thickness uniformity of 1% and compositional uniformity of 2% and 5% for Y/Ba and Cu/Ba, respectively. The films show a surface morphology with low defect density ( 2 ) and excellent superconducting properties (T c (50%) > 90 K, j c (T=77 K, B=0T) > 5 x 10 6 A cm -2 ). The residual contamination by fluorine was determined by SIMS to be less than 250 ppm. This gives the strong evidence that this industrial process can be transferred to the multiwafer planetary reactors trademark for mass production. (orig.)

  1. Growth of magnesium diboride films on 2 inch diameter copper discs by hybrid physical–chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Withanage, Wenura K.; Xi, X. X.; Nassiri, Alireza; Lee, Namhoon; Wolak, Matthäus A.; Tan, Teng; Welander, Paul B.; Franzi, Matthew; Tantawi, Sami; Kustom, Robert L.

    2017-02-16

    Magnesium diboride (MgB2) coating is a potential candidate to replace bulk niobium (Nb) for superconducting radio frequency cavities due to the appealing superconducting properties of MgB2. MgB2 coating on copper may allow cavity operation near 20–25 K as a result of the high transition temperature (T c) of MgB2 and excellent thermal conductivity of Cu. We have grown MgB2 films on 2 inch diameter Cu discs by hybrid physical–chemical vapor deposition for radio frequency characterization. Structural and elemental analyses showed a uniform MgB2 coating on top of a Mg–Cu alloy layer with occasional intrusion of Mg–Cu alloy regions. High T c values of around 37 K and high critical current density (J c) on the order of 107 A cm-2 at zero field were observed. Radio frequency measurements at 11.4 GHz confirmed a high T c and showed a quality factor (Q 0) much higher than for Cu and close to that of Nb.

  2. Growth of magnesium diboride films on 2 inch diameter copper discs by hybrid physical-chemical vapor deposition

    Science.gov (United States)

    Withanage, Wenura K.; Xi, X. X.; Nassiri, Alireza; Lee, Namhoon; Wolak, Matthäus A.; Tan, Teng; Welander, Paul B.; Franzi, Matthew; Tantawi, Sami; Kustom, Robert L.

    2017-04-01

    Magnesium diboride (MgB2) coating is a potential candidate to replace bulk niobium (Nb) for superconducting radio frequency cavities due to the appealing superconducting properties of MgB2. MgB2 coating on copper may allow cavity operation near 20-25 K as a result of the high transition temperature (T c) of MgB2 and excellent thermal conductivity of Cu. We have grown MgB2 films on 2 inch diameter Cu discs by hybrid physical-chemical vapor deposition for radio frequency characterization. Structural and elemental analyses showed a uniform MgB2 coating on top of a Mg-Cu alloy layer with occasional intrusion of Mg-Cu alloy regions. High T c values of around 37 K and high critical current density (J c) on the order of 107 A cm-2 at zero field were observed. Radio frequency measurements at 11.4 GHz confirmed a high T c and showed a quality factor (Q 0) much higher than for Cu and close to that of Nb.

  3. Growth and characterization of stoichiometric BCN films on highly oriented pyrolytic graphite by radiofrequency plasma enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mannan, Md. Abdul, E-mail: amannan75@yahoo.co [Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo, Saga 840-8502 (Japan); Synchrotron Radiation Research Unit, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Noguchi, Hideyuki; Kida, Tetsuya; Nagano, Masamitsu [Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo, Saga 840-8502 (Japan); Hirao, Norie; Baba, Yuji [Synchrotron Radiation Research Unit, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2010-05-31

    Hexagonal boron carbonitride (h-BCN) hybrid films have been synthesized on highly oriented pyrolytic graphite by radiofrequency plasma enhanced chemical vapor deposition using tris-(dimethylamino)borane as a single-source molecular precursor. The films were characterized by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) and Raman spectroscopic measurements. XPS measurement showed that the B atoms were bonded to C and N atoms to form the sp{sup 2}-B-C-N atomic hybrid chemical environment. The atomic composition estimated from the XPS of the typical sample was found to be almost B{sub 1}C{sub 1}N{sub 1}. NEXAFS spectra of the B K-edge and the N K-edge had the peaks due to the {pi}* and {sigma}* resonances of sp{sup 2} hybrid orbitals implying the existence of the sp{sup 2} hybrid configurations of h-BCN around the B atoms. The G band at 1592 and D band at 1352 cm{sup -1} in the Raman spectra also suggested the presence of the graphite-like sp{sup 2}-B-C-N atomic hybrid bonds. The films consisted of micrometer scale crystalline structure of around 10 {mu}m thick has been confirmed by the field emission scanning electron microscopy.

  4. Growth behaviors and biocidal properties of titanium dioxide films depending on nucleation duration in liquid phase deposition

    Science.gov (United States)

    Park, Sohyeon; Park, Joohee; Heo, Jiwoong; Hong, Bo Young; Hong, Jinkee

    2017-12-01

    Liquid phase deposition (LPD), which is a method to directly form a titanium dioxide (TiO2) film on a substrate, is the most practical method for applying TiO2 films to medical devices because it is performed at lower temperatures than other methods. The TiO2 films to be applied to medical devices should offer excellent antibacterial effect, but should be stable to normal cells and have appropriate strength. In this research, we observed that the size, shape, and density of TiO2 particles varied with the nucleation duration in LPD and confirmed that these results caused changes in several properties including the mechanical properties, cytotoxicity and antibacterial effect of TiO2 films. From the analysis of these results, we established the conditions for the preparation of TiO2 films that are suitable for medical devices and suggest a new approach to the study of TiO2 films prepared by LPD.

  5. Growth graphene on silver-copper nanoparticles by chemical vapor deposition for high-performance surface-enhanced Raman scattering

    Science.gov (United States)

    Zhang, Xiumei; Xu, Shicai; Jiang, Shouzhen; Wang, Jihua; Wei, Jie; Xu, Shida; Gao, Shoubao; Liu, Hanping; Qiu, Hengwei; Li, Zhen; Liu, Huilan; Li, Zhenhua; Li, Hongsheng

    2015-10-01

    We present a graphene/silver-copper nanoparticle hybrid system (G/SCNPs) to be used as a high-performance surface-enhanced Raman scattering (SERS) substrate. The silver-copper nanoparticles wrapped by a monolayer graphene layer are directly synthesized on SiO2/Si substrate by chemical vapor deposition in a mixture of methane and hydrogen. The G/SCNPs shows excellent SERS enhancement activity and high reproducibility. The minimum detected concentration of R6G is as low as 10-10 M and the calibration curve shows a good linear response from 10-6 to 10-10 M. The date fluctuations from 20 positions of one SERS substrate are less than 8% and from 20 different substrates are less than 10%. The high reproducibility of the enhanced Raman signals could be due to the presence of an ultrathin graphene layer and uniform morphology of silver-copper nanoparticles. The use of G/SCNPs for detection of nucleosides extracted from human urine demonstrates great potential for the practical applications on a variety of detection in medicine and biotechnology field.

  6. Buriti oil (Mauritia flexuosa L.) negatively impacts somatic growth and reflex maturation and increases retinol deposition in young rats.

    Science.gov (United States)

    Medeiros, Maria C; Aquino, Jailane S; Soares, Juliana; Figueiroa, Edigleide B; Mesquita, Hanni M; Pessoa, Debora C; Stamford, Tania M

    2015-11-01

    Buriti oil contains nutrients such as essential fatty acids and vitamins, which are directly involved with neonates' development. However, the refining process of this oil can change its nutrient profile. This study investigated the effects of maternal consumption of Buriti oil (crude or refined), on reflex and somatic development and retinol levels in neonatal rats. Thirty-six Wistar male neonate rats born from mothers who consumed diet with 7% lipids during gestation and lactation were used. Rats were randomized into three groups: rats receiving diet added of soybean oil (control-CG), crude Buriti oil (CB) and refined Buriti oil (RB). Offspring weight, tail length, reflex ontogeny and somatic maturation were assessed during lactation. At the end of the experiment, serum and liver retinol concentrations were measured. Animals from CB and RB groups showed delayed onset of palm grasp, righting reflex and cliff avoidance reflexes compared to the control group (CG). However, animals from RB group showed anticipation of auditory startle compared to those from BC group. Regarding somatic maturation indicators, animals from RB group showed delayed eye opening and eruption of superior and inferior incisors in relation to control and anticipation in the auditory conduit opening in relation to CB group. Rats from CB and RB groups showed higher serum and liver vitamin A contents. Buriti oil delays physical parameters and reflex maturation and increases serum and liver retinol deposition among neonatal rats. Copyright © 2015. Published by Elsevier Ltd.

  7. The Role of Participation Banking as Alternative Financing Channels to Substitute for Deposit Banks and its Growth in the Turkish Finance Market - Period: 2007-2015

    Directory of Open Access Journals (Sweden)

    Ferhat Sayım

    2017-09-01

    Full Text Available Financial systems and companies have become the most important reasons in the weakness of world economic system. The formation and development process of the financial structure also constitute the infrastructure of the world economic system. The path of the financial system and development has led to discuss with the financial crisis in 2008-2011. One of the solutions in order to reduce problems caused by the conventional banking system is alternative financing systems. In Turkey, the corporations based on profit share system are named participation banks. These banks which settle on different principles in the risk distribution of the portfolio acquired are analyzed more nowadays. Participation based banks are placed in practically every regulation related to banking terms and get their legal infrastructure more steady in the banking legislation of Turkey. This study is a continuation of a series related to the situation of participation banking in Turkey. On the other hand, the literature and the history of participation banking have been given less attention in this study. Literature information on methods in participation banks has been described in previous work of the series. Two analyzes were conducted in this study. One analysis is interpretive analysis that expresses the situation of applications of participation banking against banking risks. The other is an analysis of the figures of participation banks in Turkey as a continuation of the series. This study is a 2007-2015 part of research series. The study tries to explore the place and the importance of participation based banking with the various sub-headings, especially in Turkey. For this reason, we examine the comparative review 2007-2015 data of participation banks which are composed of Total Assets, Equity Net Profit, Collected Funds and Bank Loan Funds. Then we compare the total figures with deposit banks for the same period in Turkey.

  8. Influence of plasma pressure on the growth characteristics and ferroelectric properties of sputter-deposited PZT thin films

    International Nuclear Information System (INIS)

    Bose, A.; Maity, T.; Bysakh, S.; Seal, A.; Sen, Suchitra

    2010-01-01

    PZT thin films of thickness (320-1040) nm were synthesized on Si/SiO 2 /Ti/Pt multilayered substrates by radio frequency magnetron sputtering. The influence of plasma pressure in the range of (0.24-4.9) Pa, during deposition, on the structural, electrical and ferroelectric properties of the PZT films was systematically studied. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and cross-sectional transmission electron microscopy (XTEM) were employed for structural study. Nano-probe Energy Dispersive (EDX) line scanning was employed to investigate the elemental distribution across the film-bottom electrode interface. I-V characteristics and polarization-electric field (P-E) hysteresis loop of the films were measured. The study reveals that the plasma pressure has a strong influence on the evolution and texture of the ferroelectric perovskite phase and microstructure of the films. At an optimum plasma pressure of 4.1 Pa, PZT films are grown with 93% perovskite phase with (1 1 1) preferred orientation and uniform granular microstructure. These films show a saturation polarization of 67 μC/cm 2 , remnant polarization of 30 μC/cm 2 and coercive field of 28 kV/cm which, according to the literature, seem to be suitable for device applications. Transmission electron microscopy (TEM) study shows that at a plasma pressure of 4.1 Pa, the PZT/bottom Pt interface is sharp and no amorphous interlayer is formed at the interface. At a higher plasma pressure of 4.9 Pa, poor I-V and P-E hysteresis loop are observed which are interpreted as due to an amorphous interlayer at the film-bottom electrode interface which is possibly enriched in Pb, Zr, O and Pt.

  9. Anomalous growth of whisker-like bismuth-tin extrusions from tin-enriched tin-Bi deposits

    International Nuclear Information System (INIS)

    Hu, C.-C.; Tsai, Y.-D.; Lin, C.-C.; Lee, G.-L.; Chen, S.-W.; Lee, T.-C.; Wen, T.-C.

    2009-01-01

    This article shows the first finding that the anomalous growth of Bi-Sn extrusions from tin-enriched alloys (Sn-xBi with x between 20 and 10 wt.%) can be induced by post-plating annealing in N 2 between 145 and 260 deg. C for 10 min although metal whiskers were commonly formed on the surface of pure metals or alloys of the enriched component. From SEM observations, very similar to Sn whiskers, Bi-Sn extrusions vary in size, shape, length, and diameter with changing the annealing temperature, which are highly important in regarding the potential for failure of electronic products. Annealing resulting in thermal expansion of Sn grains is believed to squeeze the Bi-Sn alloys with relatively low melting points to form whisker-like extrusions although the exact mechanism is unclear

  10. Biological Petri Nets

    CERN Document Server

    Wingender, E

    2011-01-01

    It was suggested some years ago that Petri nets might be well suited to modeling metabolic networks, overcoming some of the limitations encountered by the use of systems employing ODEs (ordinary differential equations). Much work has been done since then which confirms this and demonstrates the usefulness of this concept for systems biology. Petri net technology is not only intuitively understood by scientists trained in the life sciences, it also has a robust mathematical foundation and provides the required degree of flexibility. As a result it appears to be a very promising approach to mode

  11. Reconfiguration of distribution nets

    International Nuclear Information System (INIS)

    Latorre Bayona, Gerardo; Angarita Marquez, Jorge Luis

    2000-01-01

    Starting of the location of the reconfiguration problem inside the context of the operation of distribution nets, of the quality indicators definition and of the presentation of the alternatives more used for reduction of technical losses, they are related diverse reconfiguration methodologies proposed in the technical literature, pointing out their three principals limitations; also are presents the results of lost obtained starting from simulation works carried out in distribution circuits of the ESSA ESP, which permitting to postulate the reconfiguration of nets like an excellent alternative to reduce technical losses

  12. NET system integration

    International Nuclear Information System (INIS)

    Farfaletti-Casali, F.; Mitchell, N.; Salpietro, E.; Buzzi, U.; Gritzmann, P.

    1985-01-01

    The NET system integration procedure is the process by which the requirements of the various Tokamak machine design areas are brought together to form a compatible machine layout. Each design area produces requirements which generally allow components to be built at minimum cost and operate with minimum technical risk, and the final machine assembly should be achieved with minimum departure from these optimum designs. This is carried out in NET by allowing flexibility in the maintenance and access methods to the machine internal components which must be regularly replaced by remote handling, in segmentation of these internal components and in the number of toroidal field coils

  13. Improving the growth of Ge/Si islands by modulating the spacing between screen and accelerator grids in ion beam sputtering deposition system

    International Nuclear Information System (INIS)

    Yang, Jie; Zhao, Bo; Wang, Chong; Qiu, Feng; Wang, Rongfei; Yang, Yu

    2016-01-01

    Highlights: • Ge islands were prepared by ion beam sputtering with different grid-to-grid gaps. • Ge islands with larger sizes and low density are observed in 1-mm-spaced samples. • The island growth was determined by sputter energy and the quality of Si buffer. • The crystalline volume fraction of buffer must be higher than 72% to grow islands. - Abstract: Ge islands were fabricated on Si buffer layer by ion beam sputtering deposition with a spacing between the screen and accelerator grids of either 1 mm or 2 mm. The Si buffer layer exhibits mixed-phase microcrystallinity for samples grown with 1 mm spacing and crystallinity for those with 2 mm spacing. Ge islands are larger and less dense than those grown on the crystalline buffer because of the selective growth mechanism on the microcrystalline buffer. Moreover, the nucleation site of Ge islands formed on the crystalline Si buffer is random. Ge islands grown at different grid-to-grid gaps are characterized by two key factors, namely, divergence half angle of ion beam and crystallinity of buffer layer. High grid-to-grid spacing results in small divergence half angle, thereby enhancing the sputtering energy and redistribution of sputtered atoms. The crystalline volume fraction of the microcrystalline Si buffer was obtained based on the integrated intensity ratio of Raman peaks. The islands show decreased density with decreasing crystalline volume fraction and are difficult to observe at crystalline volume fractions lower than 72%.

  14. Improving the growth of Ge/Si islands by modulating the spacing between screen and accelerator grids in ion beam sputtering deposition system

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jie; Zhao, Bo [Institute of Optoelectronic Information Materials, School of Materials Science and Engineering, Yunnan University, Kunming 650091 (China); Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming 650091 (China); Wang, Chong, E-mail: cwang@mail.sitp.ac.cn [Institute of Optoelectronic Information Materials, School of Materials Science and Engineering, Yunnan University, Kunming 650091 (China); Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming 650091 (China); Qiu, Feng; Wang, Rongfei [Institute of Optoelectronic Information Materials, School of Materials Science and Engineering, Yunnan University, Kunming 650091 (China); Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming 650091 (China); Yang, Yu, E-mail: yuyang@ynu.edu.cn [Institute of Optoelectronic Information Materials, School of Materials Science and Engineering, Yunnan University, Kunming 650091 (China); Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming 650091 (China)

    2016-11-15

    Highlights: • Ge islands were prepared by ion beam sputtering with different grid-to-grid gaps. • Ge islands with larger sizes and low density are observed in 1-mm-spaced samples. • The island growth was determined by sputter energy and the quality of Si buffer. • The crystalline volume fraction of buffer must be higher than 72% to grow islands. - Abstract: Ge islands were fabricated on Si buffer layer by ion beam sputtering deposition with a spacing between the screen and accelerator grids of either 1 mm or 2 mm. The Si buffer layer exhibits mixed-phase microcrystallinity for samples grown with 1 mm spacing and crystallinity for those with 2 mm spacing. Ge islands are larger and less dense than those grown on the crystalline buffer because of the selective growth mechanism on the microcrystalline buffer. Moreover, the nucleation site of Ge islands formed on the crystalline Si buffer is random. Ge islands grown at different grid-to-grid gaps are characterized by two key factors, namely, divergence half angle of ion beam and crystallinity of buffer layer. High grid-to-grid spacing results in small divergence half angle, thereby enhancing the sputtering energy and redistribution of sputtered atoms. The crystalline volume fraction of the microcrystalline Si buffer was obtained based on the integrated intensity ratio of Raman peaks. The islands show decreased density with decreasing crystalline volume fraction and are difficult to observe at crystalline volume fractions lower than 72%.

  15. Self-assembled growth and structural analysis of inclined GaN nanorods on nanoimprinted m-sapphire using catalyst-free metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyuseung; Chae, Sooryong; Jang, Jongjin; Min, Daehong; Kim, Jaehwan; Nam, Okhyun, E-mail: ohnam@kpu.ac.kr [Convergence Center for Advanced Nano Semiconductor (CANS), Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung, 15073 (Korea, Republic of)

    2016-04-15

    In this study, self-assembled inclined (1-10-3)-oriented GaN nanorods (NRs) were grown on nanoimprinted (10-10) m-sapphire substrates using catalyst-free metal-organic chemical vapor deposition. According to X-ray phi-scans, the inclined GaN NRs were tilted at an angle of ∼57.5° to the [10-10]{sub sapp} direction. Specifically, the GaN NRs grew in a single inclined direction to the [11-20]{sub sapp}. Uni-directionally inclined NRs were formed through the one-sided (10-11)-faceted growth of the interfacial a-GaN plane layer. It was confirmed that a thin layer of a-GaN was formed on r-facet nanogrooves of the m-sapphire substrate by nitridation. The interfacial a-GaN nucleation affected both the inclined angle and the growth direction of the inclined GaN NRs. Using X-ray diffraction and selective area electron diffraction, the epitaxial relationship between the inclined (1-10-3) GaN NRs and interfacial a-GaN layer on m-sapphire substrates was systematically investigated. Moreover, the inclined GaN NRs were observed to be mostly free of stacking fault-related defects using high-resolution transmission electron microscopy.

  16. Low Temperature (180°C Growth of Smooth Surface Germanium Epilayers on Silicon Substrates Using Electron Cyclotron Resonance Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Teng-Hsiang Chang

    2014-01-01

    Full Text Available This paper describes a new method to grow thin germanium (Ge epilayers (40 nm on c-Si substrates at a low growth temperature of 180°C using electron cyclotron resonance chemical vapor deposition (ECR-CVD process. The full width at half maximum (FWHM of the Ge (004 in X-ray diffraction pattern and the compressive stain in a Ge epilayer of 683 arcsec and 0.12% can be achieved. Moreover, the Ge/Si interface is observed by transmission electron microscopy to demonstrate the epitaxial growth of Ge on Si and the surface roughness is 0.342 nm. The thin-thickness and smooth surface of Ge epilayer grown on Si in this study is suitable to be a virtual substrate for developing the low cost and high efficiency III-V/Si tandem solar cells in our opinion. Furthermore, the low temperature process can not only decrease costs but can also reduce the restriction of high temperature processes on device manufacturing.

  17. Growth and characterization of germanium epitaxial film on silicon (001 with germane precursor in metal organic chemical vapour deposition (MOCVD chamber

    Directory of Open Access Journals (Sweden)

    Kwang Hong Lee

    2013-09-01

    Full Text Available The quality of germanium (Ge epitaxial film grown directly on a silicon (Si (001 substrate with 6° off-cut using conventional germane precursor in a metal organic chemical vapour deposition (MOCVD system is studied. The growth sequence consists of several steps at low temperature (LT at 400 °C, intermediate temperature ramp (LT-HT of ∼10 °C/min and high temperature (HT at 600 °C. This is followed by post-growth annealing in hydrogen at temperature ranging from 650 to 825 °C. The Ge epitaxial film of thickness ∼ 1 μm experiences thermally induced tensile strain of 0.11 % with a treading dislocation density (TDD of ∼107/cm2 and the root-mean-square (RMS roughness of ∼ 0.75 nm. The benefit of growing Ge epitaxial film using MOCVD is that the subsequent III-V materials can be grown in-situ without the need of breaking the vacuum hence it is manufacturing worthy.

  18. A benchmark of co-flow and cyclic deposition/etch approaches for the selective epitaxial growth of tensile-strained Si:P

    Science.gov (United States)

    Hartmann, J. M.; Veillerot, M.; Prévitali, B.

    2017-10-01

    We have compared co-flow and cyclic deposition/etch processes for the selective epitaxial growth of Si:P layers. High growth rates, relatively low resistivities and significant amounts of tensile strain (up to 10 nm min-1, 0.55 mOhm cm and a strain equivalent to 1.06% of substitutional C in Si:C layers) were obtained at 700 °C, 760 Torr with a co-flow approach and a SiH2Cl2 + PH3 + HCl chemistry. This approach was successfully used to thicken the sources and drains regions of n-type fin-shaped Field Effect Transistors. Meanwhile, the (Si2H6 + PH3/HCl + GeH4) CDE process evaluated yielded at 600 °C, 80 Torr even lower resistivities (0.4 mOhm cm, typically), at the cost however of the tensile strain which was lost due to (i) the incorporation of Ge atoms (1.5%, typically) into the lattice during the selective etch steps and (ii) a reduction by a factor of two of the P atomic concentration in CDE layers compared to that in layers grown in a single step (5 × 1020 cm-3 compared to 1021 cm-3).

  19. Growth mode, magnetic and magneto-optical properties of pulsed-laser-deposited Au/Co/Au(1 1 1) trilayers

    International Nuclear Information System (INIS)

    Clavero, C.; Cebollada, A.; Armelles, G.; Fruchart, O.

    2010-01-01

    The growth mode, magnetic and magneto-optical properties of epitaxial Au/Co/Au(1 1 1) ultrathin trilayers grown by pulsed-laser deposition (PLD) under ultra-high vacuum are presented. Sapphire wafers buffered with a single-crystalline Mo(1 1 0) buffer layer were used as substrates. Owing to PLD-induced interfacial intermixing at the lower Co/Au(1 1 1) interface, a close-to layer-by-layer growth mode is promoted. Surprisingly, despite this intermixing, ferromagnetic behavior is found at room temperature for coverings starting at 1 atomic layer (AL). The films display perpendicular magnetization with anisotropy constants reduced by 50% compared to TD-grown or electrodeposited films, and with a coercivity more than one order of magnitude lower (≤5mT). The magneto-optical (MO) response in the low Co thickness range is dominated by Au/Co interface contributions. For thicknesses starting at 3 AL Co, the MO response has a linear dependence with the Co thickness, indicative of a continuous-film-like MO behavior.

  20. Self-Catalyzed Growth and Characterization of In(As)P Nanowires on InP(111)B Using Metal-Organic Chemical Vapor Deposition.

    Science.gov (United States)

    Park, Jeung Hun; Pozuelo, Marta; Setiawan, Bunga P D; Chung, Choong-Heui

    2016-12-01

    We report the growth of vertical -oriented InAs x P1-x (0.11 ≤ x ≤ 0.27) nanowires via metal-organic chemical vapor deposition in the presence of indium droplets as catalysts on InP(111)B substrates at 375 °C. Trimethylindium, tertiarybutylphosphine, and tertiarybutylarsine are used as the precursors, corresponding to P/In and As/In molar ratios of 29 and 0.01, respectively. The as-grown nanowire growth morphologies, crystallinity, composition, and optical characteristics are determined using a combination of scanning and transmission electron microscopies, electron diffraction, and X-ray photoelectron, energy dispersive X-ray, and Raman spectroscopies. We find that the InAs x P1-x nanowires are tapered with narrow tops, wider bases, and In-rich In-As alloy tips, characteristic of vapor-liquid-solid process. The wires exhibit a mixture of zinc blende and wurtzite crystal structures and a high density of structural defects such as stacking faults and twins. Our results suggest that the incorporation of As into InP wires decreases with increasing substrate temperature. The Raman spectra obtained from the In(As)P nanowires reveal a red-shift and lower intensity of longitudinal optical mode relative to both InP nanowires and InP(111)B bulk, due to the incorporation of As into the InP matrix.

  1. 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

  2. Low-temperature growth of highly crystalline β-Ga2O3 nanowires by solid-source chemical vapor deposition.

    Science.gov (United States)

    Han, Ning; Wang, Fengyun; Yang, Zaixing; Yip, SenPo; Dong, Guofa; Lin, Hao; Fang, Ming; Hung, TakFu; Ho, Johnny C

    2014-01-01

    Growing Ga2O3 dielectric materials at a moderately low temperature is important for the further development of high-mobility III-V semiconductor-based nanoelectronics. Here, β-Ga2O3 nanowires are successfully synthesized at a relatively low temperature of 610°C by solid-source chemical vapor deposition employing GaAs powders as the source material, which is in a distinct contrast to the typical synthesis temperature of above 1,000°C as reported by other methods. In this work, the prepared β-Ga2O3 nanowires are mainly composed of Ga and O elements with an atomic ratio of approximately 2:3. Importantly, they are highly crystalline in the monoclinic structure with varied growth orientations in low-index planes. The bandgap of the β-Ga2O3 nanowires is determined to be 251 nm (approximately 4.94 eV), in good accordance with the literature. Also, electrical characterization reveals that the individual nanowire has a resistivity of up to 8.5 × 10(7) Ω cm, when fabricated in the configuration of parallel arrays, further indicating the promise of growing these highly insulating Ga2O3 materials in this III-V nanowire-compatible growth condition. 77.55.D; 61.46.Km; 78.40.Fy.

  3. Simulation of Silver Thin Films' Growth and Influence of Deposition Rate on Final Grain Size under Angle Flux and Standard Situation

    Directory of Open Access Journals (Sweden)

    Maryam Jamshidnejad

    2011-01-01

    Full Text Available In this paper, a 2D stimulation model, FACET, is used for investigation of the relation between micro structure and deposition conditions such as substrate temperature, deposition rate and deposition angle of Ag thin films. It is observed that by increasing the deposition rate in standard conditions providing that the temperature of substrate is low, the average of final grain size is decreased. While, in deposition with angle flux the average of final grain size is increased.

  4. Impact of first-step potential and time on the vertical growth of ZnO nanorods on ITO substrate by two-step electrochemical deposition

    International Nuclear Information System (INIS)

    Kim, Tae Gyoum; Jang, Jin-Tak; Ryu, Hyukhyun; Lee, Won-Jae

    2013-01-01

    Highlights: •We grew vertical ZnO nanorods on ITO substrate using a two-step continuous potential process. •The nucleation for the ZnO nanorods growth was changed by first-step potential and duration. •The vertical ZnO nanorods were well grown when first-step potential was −1.2 V and 10 s. -- Abstract: In this study, we analyzed the growth of ZnO nanorods on an ITO (indium doped tin oxide) substrate by electrochemical deposition using a two-step, continuous potential process. We examined the effect of changing the first-step potential as well as the first-step duration on the morphological, structural and optical properties of ZnO nanorods, measured via using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and photoluminescence (PL), respectively. As a result, vertical ZnO nanorods were grown on ITO substrate without the need for a template when the first-step potential was set to −1.2 V for a duration of 10 s, and the second-step potential was set to −0.7 V for a duration of 1190 s. The ZnO nanorods on this sample showed the highest XRD (0 0 2)/(1 0 0) peak intensity ratio and the highest PL near band edge emission to deep level emission peak intensity ratio (NBE/DLE). In this study, the nucleation for vertical ZnO nanorod growth on an ITO substrate was found to be affected by changes in the first-step potential and first-step duration

  5. Assessing the impacts of climate change and nitrogen deposition on Norway spruce (Picea abies L. Karst) growth in Austria with BIOME-BGC.

    Science.gov (United States)

    Eastaugh, Chris S; Pötzelsberger, Elisabeth; Hasenauer, Hubert

    2011-03-01

    The aim of this paper is to determine whether a detectable impact of climate change is apparent in Austrian forests. In regions of complex terrain such as most of Austria, climatic trends over the past 50 years show marked geographic variability. As climate is one of the key drivers of forest growth, a comparison of growth characteristics between regions with different trends in temperature and precipitation can give insights into the impact of climatic change on forests. This study uses data from several hundred climate recording stations, interpolated to measurement sites of the Austrian National Forest Inventory (NFI). Austria as a whole shows a warming trend over the past 50 years and little overall change in precipitation. The warming trends, however, vary considerably across certain regions and regional precipitation trends vary widely in both directions, which cancel out on the national scale These differences allow the delineation of 'climatic change zones' with internally consistent climatic trends that differ from other zones. This study applies the species-specific adaptation of the biogeochemical model BIOME-BGC to Norway spruce (Picea abies (L.) Karst) across a range of Austrian climatic change zones, using input data from a number of national databases. The relative influence of extant climate change on forest growth is quantified, and compared with the far greater impact of non-climatic factors. At the national scale, climate change is found to have negligible effect on Norway spruce productivity, due in part to opposing effects at the regional level. The magnitudes of the modeled non-climatic influences on aboveground woody biomass increment increases are consistent with previously reported values of 20-40 kg of added stem carbon sequestration per kilogram of additional nitrogen deposition, while climate responses are of a magnitude difficult to detect in NFI data.

  6. Growth and characterization of high-Tc Y1Ba2Cu3O7-x superconducting thin films by chemical vapor deposition

    International Nuclear Information System (INIS)

    Feng, A.

    1992-01-01

    In chapter I, the current status of high-Tc superconductors (especially Y 1 Ba 2 Cu 3 O 7-x ), their microstructures and their unique physical properties are reviewed. An introduction to the potential and importance of those high-Tc superconductors in practical applications, especially for the application of YBCO thin films in microelectronics, is given. A general description of the common YBCO thin film fabrication and characterization techniques is also presented in this first chapter. Chapter II describes a new CVD process, temperature-controlled chemical vapor deposition (TC-CVD) for the growth of YBCO superconducting thin films on substrates of practical importance, such as sapphire (Al 2 O 3 ) and on substrates of lattice matched perovskite-type single crystals, such as LaAlO 3 . In order to verify the viability of this new CVD process the qualities of YBCO superconducting thin films were examined by various characterization methods, such as resistivity vs. temperature (R vs. T), scanning electron microscopy (SEM), X-ray diffraction (XRD), and magnetic susceptibility (x) measurements. Chapter III deals with the effect of substrate temperature on the properties of YBCO thin films made by TC-CVD. The principle objective of this study is to raise the transition temperature and critical current densities of CVD YBCO superconducting thin films. Understanding the relations between YBCO film growth process and varying substrate temperatures proved to be crucial in reaching this goal. The authors present the characterization results of YBCO thin films produced by different temperature schemes, to illustrate the importance of varying substrate temperature during the film growth. In chapter IV, the Rutherford backscattering (RBS) channeling technique is described. They have used RBS channeling to characterize the epitaxial YBCO thin film's crystallinity and lattice alignment. Transmission electron microscopy studies are also included

  7. Coloured Petri Nets

    CERN Document Server

    Jensen, Kurt

    2009-01-01

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. This book introduces the constructs of the CPN modelling language and presents the related analysis methods. It provides a comprehensive road map for the practical use of CPN.

  8. Safety nets or straitjackets?

    DEFF Research Database (Denmark)

    Ilsøe, Anna

    2012-01-01

    Does regulation of working hours at national and sector level impose straitjackets, or offer safety nets to employees seeking working time flexibility? This article compares legislation and collective agreements in the metal industries of Denmark, Germany and the USA. The industry has historically...

  9. Neuronal nets in robotics

    International Nuclear Information System (INIS)

    Jimenez Sanchez, Raul

    1999-01-01

    The paper gives a generic idea of the solutions that the neuronal nets contribute to the robotics. The advantages and the inconveniences are exposed that have regarding the conventional techniques. It also describe the more excellent applications as the pursuit of trajectories, the positioning based on images, the force control or of the mobile robots management, among others

  10. Net4Care platform

    DEFF Research Database (Denmark)

    2012-01-01

    , that in turn enables general practitioners and clinical staff to view observations. Use the menus above to explore the site's information resources. To get started, follow the short Hello, World! tutorial. The Net4Care project is funded by The Central Denmark Region and EU via Caretech Innovation....

  11. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt; Kristensen, Lars Michael

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. The development of such systems is particularly challenging because of inherent intricacies like possible nondeterminism an...

  12. Game Theory .net.

    Science.gov (United States)

    Shor, Mikhael

    2003-01-01

    States making game theory relevant and accessible to students is challenging. Describes the primary goal of GameTheory.net is to provide interactive teaching tools. Indicates the site strives to unite educators from economics, political and computer science, and ecology by providing a repository of lecture notes and tests for courses using…

  13. BacillusRegNet

    DEFF Research Database (Denmark)

    Misirli, Goksel; Hallinan, Jennifer; Röttger, Richard

    2014-01-01

    As high-throughput technologies become cheaper and easier to use, raw sequence data and corresponding annotations for many organisms are becoming available. However, sequence data alone is not sufficient to explain the biological behaviour of organisms, which arises largely from complex molecular...... the associated BacillusRegNet website (http://bacillus.ncl.ac.uk)....

  14. Boom Booom Net Radio

    DEFF Research Database (Denmark)

    Grimshaw, Mark Nicholas; Yong, Louisa; Dobie, Ian

    1999-01-01

    of an existing Internet radio station; Boom Booom Net Radio. Whilst necessity dictates some use of technology-related terminology, wherever possible we have endeavoured to keep such jargon to a minimum and to either explain it in the text or to provide further explanation in the appended glossary....

  15. Effect of fuel type and deposition surface temperature on the growth and structure of ash deposit collected during co-firing of coal with sewage-sludge, saw-dust and refuse derived fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kupka, Tomasz; Zajac, Krzysztof; Weber, Roman [Clausthal Univ. of Technology, Clausthal-Zellerfeld (Germany). Inst. of Energy Process Engineering and Fuel Technology

    2008-07-01

    Blends of a South African bituminous ''Middleburg'' coal and three alternative fuels (a municipal sewage-sludge, a saw-dust and a refuse derived fuel) have been fired in the slagging reactor to examine the effect of the added fuel on slagging propensity of the mixtures. Two kinds of deposition probes have been used, un-cooled ceramic probes and air-cooled steal probes. Distinct differences in physical and chemical structures of the deposits collected using the un-cooled ceramic probes and air-cooled metal probes have been observed. Glassy, easily molten deposits collected on un-cooled ceramic deposition probes were characteristic for co-firing of municipal sewage-sludge with coal. Porous, sintered (not molten) but easily removable deposits of the same fuel blend have been collected on the air-cooled metal deposition probes. Loose, easy removable deposits have been sampled on air-cooled metal deposition probe during co-firing of coal/saw-dust blends. The mass of the deposit sampled at lower surface temperatures (550-700 C) was always larger than the mass sampled at higher temperatures (1100-1300 C) since the higher temperature ash agglomerated and sintered much faster than the low temperature deposit. (orig.)

  16. 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.

  17. 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

  18. Investigating impacts of economic growth on the environment using remote sensing tools: A case study of gross domestic product and net primary production in China from 2001 to 2007

    Science.gov (United States)

    Zhao, Naizhuo

    Pursuing sustainable co-development of economy and environment has been established as a basic national policy by the present Chinese government. However, studies regarding actual outcomes of the co-development policy at the whole Chinese scale are still limited. Detecting China's economic growth and changes of environmental quality will not only contribute to evaluation of outcomes of the co-development policy but more importantly is an opportunity to examine the suitability of the IPAT model and improve our understanding of human-environment interactions. The core of the IPAT theory is an equation where I=PxAxT that models human impact on the environment as a function of changes to population (P), affluence ( A), and technology (T). The IPAT theory emphasizes that economic growth will inevitably produce negative impacts on the environment. Thus, if China's environmental quality declined while economic growth occurred, then the IPAT theory will be substantiated. Otherwise, the suitability of the IPAT theory will be called into question and its tenets must be reconsidered. In this dissertation research I selected gross domestic product (GDP) and net primary production (NPP) as indicators to evaluate production of social and ecological systems respectively. The main study objectives are (1) to develop a methodology to facilitate integration of the two indicators derived from demographic data sources and satellite imagery at different geographic scales, (2) to jointly explore changing patterns of China's economic and ecological production (i.e., spatially and temporally coincident patterns of change in GDP and NPP) across different spatial scales, (3) to analyze whether economic growth has produced negative impacts on ecosystem production and whether the impacts correlate to the economic growth, and finally (4) to discuss whether the IPAT theory is suitable for explaining the joint changes of GDP and NPP in China or if it is in need of modification. To fulfill the

  19. SolNet

    DEFF Research Database (Denmark)

    Jordan, Ulrike; Vajen, Klaus; Bales, Chris

    2014-01-01

    -accompanying Master courses, placements of internships, and PhD scholarship projects. A new scholarship project, “SHINE”, was launched in autumn 2013 in the frame work of the Marie Curie program of the European Union (Initial Training Network, ITN). 13 PhD-scholarships on solar district heating, solar heat......SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference...... for industrial processes, as well as sorption stores and materials started in December 2013. Additionally, the project comprises a training program with five PhD courses and several workshops on solar thermal engineering that will be open also for other PhD students working in the field. The research projects...

  20. Influence of boron concentration on growth characteristic and electro-catalytic performance of boron-doped diamond electrodes prepared by direct current plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Feng Yujie; Lv Jiangwei; Liu Junfeng; Gao Na; Peng Hongyan; Chen Yuqiang

    2011-01-01

    A series of boron-doped diamond (BDD) electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) with different compositions of CH 4 /H 2 /B(OCH 3 ) 3 gas mixture. A maximum growth rate of 0.65 mg cm -2 h -1 was obtained with CH 4 /H 2 /B(OCH 3 ) 3 radio of 4/190/10 and this growth condition was also a turning point for discharge plasma stability which arose from the addition of B(OCH 3 ) 3 that changed electron energy distribution and influenced the plasma reaction. The surface coating structure and electro-catalytic performance of the BDD electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Hall test, and electrochemical measurement and electro-catalytic oxidation in phenol solution. It is suggested that the boron doping level and the thermal stress in the films are the main factors affecting the electro-catalytic characteristics of the electrodes. Low boron doping level with CH 4 /H 2 /B(OCH 3 ) 3 ratio of 4/199/1 decreased the films electrical conductivity and its electro-catalytic activity. When the carrier concentration in the films reached around 10 20 cm -3 with CH 4 /H 2 /B(OCH 3 ) 3 ratio over a range of 4/195/5-4/185/15, the thermal stress in the films was the key reason that influenced the electro-catalytic activity of the electrodes for its effect on diamond lattice expansion. Therefore, the BDD electrode with modest CH 4 /H 2 /B(OCH 3 ) 3 ratio of 4/190/10 possessed the best phenol removal efficiency.

  1. Turkey's net energy consumption

    International Nuclear Information System (INIS)

    Soezen, Adnan; Arcaklioglu, Erol; Oezkaymak, Mehmet

    2005-01-01

    The main goal of this study is to develop the equations for forecasting net energy consumption (NEC) using an artificial neural-network (ANN) technique in order to determine the future level of energy consumption in Turkey. In this study, two different models were used in order to train the neural network. In one of them, population, gross generation, installed capacity and years are used in the input layer of the network (Model 1). Other energy sources are used in input layer of network (Model 2). The net energy consumption is in the output layer for two models. Data from 1975 to 2003 are used for the training. Three years (1981, 1994 and 2003) are used only as test data to confirm this method. The statistical coefficients of multiple determinations (R 2 -value) for training data are equal to 0.99944 and 0.99913 for Models 1 and 2, respectively. Similarly, R 2 values for testing data are equal to 0.997386 and 0.999558 for Models 1 and 2, respectively. According to the results, the net energy consumption using the ANN technique has been predicted with acceptable accuracy. Apart from reducing the whole time required, with the ANN approach, it is possible to find solutions that make energy applications more viable and thus more attractive to potential users. It is also expected that this study will be helpful in developing highly applicable energy policies

  2. The growth of high density network of MOF nano-crystals across macroporous metal substrates - Solvothermal synthesis versus rapid thermal deposition

    Science.gov (United States)

    Maina, James W.; Gonzalo, Cristina Pozo; Merenda, Andrea; Kong, Lingxue; Schütz, Jürg A.; Dumée, Ludovic F.

    2018-01-01

    Fabrication of metal organic framework (MOF) films and membranes across macro-porous metal substrates is extremely challenging, due to the large pore sizes across the substrates, poor wettability, and the lack of sufficient reactive functional groups on the surface, which prevent high density nucleation of MOF crystals. Herein, macroporous stainless steel substrates (pore size 44 × 40 μm) are functionalized with amine functional groups, and the growth of ZIF-8 crystals investigated through both solvothermal synthesis and rapid thermal deposition (RTD), to assess the role of synthesis routes in the resultant membranes microstructure, and subsequently their performance. Although a high density of well interconnected MOF crystals was observed across the modified substrates following both techniques, RTD was found to be a much more efficient route, yielding high quality membranes under 1 h, as opposed to the 24 h required for solvothermal synthesis. The RTD membranes also exhibited high gas permeance, with He permeance of up to 2.954 ± 0.119 × 10-6 mol m-2 s-1 Pa-1, and Knudsen selectivities for He/N2, Ar/N2 and CO2/N2, suggesting the membranes were almost defect free. This work opens up route for efficient fabrication of MOF films and membranes across macro-porous metal supports, with potential application in electrically mediated separation applications.

  3. RETADD-II: a long-range atmospheric trajectory model with consistent treatment of deposition loss and species growth and decay

    International Nuclear Information System (INIS)

    Murphy, B.D.; Ohr, S.Y.; Begovich, C.L.

    1984-08-01

    A versatile model is described which estimates long-range atmospheric dispersion based on plume trajectories. This model allows the treatment of the dispersal from a source at an arbitrary height while taking account of plume depletion by dry and wet deposition together with the decay of material to successor species. The plume depletion, decay and growth equations are solved in an efficient manner which can accommodate up to eight pollutants (i.e., a parent and seven serial decay products). The code is particularly suitable for applications involving radioactive chain decay or for cases involving chemical species with successor decay products. Arbitrary emission rates can be specified for the members of the chain or, as is commonly the case, a sole emission rate can be specified for the first member. The code uses readily available upper-air wind data for the North American continent and it is therefore intended for the estimation of regional or continental scale dispersion patterns. This code is one of a group of codes, the Computerized Radiological Risk Investigation System (Baes and Miller, 1981), designed to simulate the transport of radionuclides through environmental pathways. 24 references, 5 figures

  4. Towards Sustainable Aquafeeds: Complete Substitution of Fish Oil with Marine Microalga Schizochytrium sp. Improves Growth and Fatty Acid Deposition in Juvenile Nile Tilapia (Oreochromis niloticus)

    Science.gov (United States)

    Sarker, Pallab K.; Kapuscinski, Anne R.; Lanois, Alison J.; Livesey, Erin D.; Bernhard, Katie P.; Coley, Mariah L.

    2016-01-01

    We conducted a 84-day nutritional feeding experiment with dried whole cells of DHA-rich marine microalga Schizochytrium sp. (Sc) to determine the optimum level of fish-oil substitution (partial or complete) for maximum growth of Nile tilapia. When we fully replaced fish oil with Schizochytrium (Sc100 diet), we found significantly higher weight gain and protein efficiency ratio (PER), and lower (improved) feed conversion ratio (FCR) and feed intake compared to a control diet containing fish oil (Sc0); and no significant change in SGR and survival rate among all diets. The Sc100 diet had the highest contents of 22:6n3 DHA, led to the highest DHA content in fillets, and consequently led to the highest DHA:EPA ratios in tilapia fillets. Schizochytrium sp. is a high quality candidate for complete substitution of fish oil in juvenile Nile tilapia feeds, providing an innovative means to formulate and optimize the composition of tilapia juvenile feed while simultaneously raising feed efficiency of tilapia aquaculture and to further develop environmentally and socially sustainable aquafeeds. Results show that replacing fish oil with DHA-rich marine Sc improves the deposition of n3 LC PUFA levels in tilapia fillet. These results support further studies to lower Schizochytrium production costs and to combine different marine microalgae to replace fish oil and fishmeal into aquafeeds. PMID:27258552

  5. CoSi2 growth on Si(001) by reactive deposition epitaxy: Effects of high-flux, low-energy ion irradiation

    International Nuclear Information System (INIS)

    Lim, C. W.; Greene, J. E.; Petrov, I.

    2006-01-01

    CoSi 2 layers, CoSi 2 (parallel sign)(001) Si and [100] CoSi 2 (parallel sign)[100] Si , contain fourfold symmetric (111) twinned domains oriented such that (221) CoSi 2 (parallel sign)(001) Si and CoSi 2 (parallel sign)[110] Si . We demonstrate that high-flux low-energy (E Ar + =9.6 eV) Ar + ion irradiation during deposition dramatically increases the area fraction f u of untwinned regions from 0.17 in films grown under standard magnetically balanced conditions in which the ratio J Ar + /J Co of the incident Ar + to Co fluxes is 1.4 to 0.72 with J Ar + /J Co =13.3. TEM analyses show that the early stages of RDE CoSi 2 (001) film growth proceed via the Volmer-Weber mode with independent nucleation of both untwinned and twinned islands. Increasing J Ar + /J Co results in larger values of both the number density and area of untwinned with respect to twinned islands. The intense Ar + ion bombardment creates additional low-energy adsorption sites that favor the nucleation of untwinned islands while collisionally enhancing Co surface mobilities which, in turn, increases the probability of itinerant Co adatoms reaching these sites

  6. The Effect of Alumina and Magnesia Supported Germanium Nanoparticles on the Growth of Carbon Nanotubes in the Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    Ghazaleh Allaedini

    2015-01-01

    Full Text Available The effect of alumina and magnesia supported germanium (Ge nanoparticles on the synthesis of carbon nanotubes (CNTs using the chemical vapor deposition (CVD method in atmospheric pressure was investigated. The TEM micrographs confirmed the formation of carbon nanotubes, and the field emission scanning electron microscopy (FESEM analysis suggested a tip-growth mechanism for the grown carbon nanotubes. The X-ray diffraction (XRD pattern indicated a graphitic nature of the carbon nanotubes. The obtained CNTs using Ge nanoparticles supported by MgO resulted in a higher degree of graphitization than the CNTs obtained using Ge nanoparticles supported by Al2O3. Raman spectroscopy analysis of the CNTs confirmed the presence of radial breathing modes (RBM, which verified the formation of CNTs. High frequency Raman analysis demonstrated that the degree of graphitization of the synthesized CNTs using magnesia supported Ge nanoparticles is higher than that of the alumina supported Ge nanoparticles with the values of (ID/IG ratios equal to 0.45 and 0.73, respectively.

  7. Epitaxial growth of InN on c-plane sapphire by pulsed laser deposition with r.f. nitrogen radical source

    International Nuclear Information System (INIS)

    Ohta, J.; Fujioka, H.; Honke, T.; Oshima, M.

    2004-01-01

    We have grown InN films on c-plane sapphire substrates by pulsed laser deposition (PLD) with a radio frequency nitrogen radical source for the first time and investigated the effect of the substrate surface nitridation on the structural and electrical properties of InN films with reflection high energy electron diffraction (RHEED), atomic force microscope, the Hall effect measurements and high-resolution X-ray diffraction (HRXRD). RHEED and HRXRD characterizations revealed that high-quality InN grows epitaxially on sapphire by PLD and its epitaxial relationship is InN (0 0 0 1) parallel sapphire (0 0 0 1) and InN [2 -1 -1 0] parallel sapphire [1 0 -1 0]. The InN crystalline quality and the electron mobility are improved by the substrate nitridation process. The area of the pits at the InN surface is reduced by the substrate nitridation process probably due to the reduction in the interface energy between InN and the substrate. The full width at half maximum of the -1 -1 2 4 X-ray rocking curve for InN grown by the present technique without using any buffer layers was as small as 34.8 arcmin. These results indicate that the present technique is promising for the growth of the high-quality InN films

  8. Net one, net two: the primary care network income statement.

    Science.gov (United States)

    Halley, M D; Little, A W

    1999-10-01

    Although hospital-owned primary care practices have been unprofitable for most hospitals, some hospitals are achieving competitive advantage and sustainable practice operations. A key to the success of some has been a net income reporting tool that separates practice operating expenses from the costs of creating and operating a network of practices to help healthcare organization managers, physicians, and staff to identify opportunities to improve the network's financial performance. This "Net One, Net Two" reporting allows operations leadership to be held accountable for Net One expenses and strategic leadership to be held accountable for Net Two expenses.

  9. Proof Nets for Lambek Calculus

    NARCIS (Netherlands)

    Roorda, Dirk

    1992-01-01

    The proof nets of linear logic are adapted to the non-commutative Lambek calculus. A different criterion for soundness of proof nets is given, which gives rise to new algorithms for proof search. The order sensitiveness of the Lambek calculus is reflected by the planarity condition on proof nets;

  10. Net metering: zero electricity bill

    International Nuclear Information System (INIS)

    Mangi, A.; Khan, Z.

    2011-01-01

    Worldwide move towards renewable energy sources, environmental concerns and decentralization of the power sector have made net metering an attractive option for power generation at small scale. This paper discusses the net metering, economical issues of renewable sources in Pakistan, technical aspects, installation suitability according to varying terrain, existing utility rules and formulation of legislation for net metering making it economically attractive. (author)

  11. The Net Advance of Physics

    Science.gov (United States)

    THE NET ADVANCE OF PHYSICS Review Articles and Tutorials in an Encyclopædic Format Established 1995 [Link to MIT] Computer support for The Net Advance of Physics is furnished by The Massachusetts Newest Additions SPECIAL FEATURES: Net Advance RETRO: Nineteenth Century Physics History of Science

  12. Horizontal ichthyoplankton tow-net system with unobstructed net opening

    Science.gov (United States)

    Nester, Robert T.

    1987-01-01

    The larval fish sampler described here consists of a modified bridle, frame, and net system with an obstruction-free net opening and is small enough for use on boats 10 m or less in length. The tow net features a square net frame attached to a 0.5-m-diameter cylinder-on-cone plankton net with a bridle designed to eliminate all obstructions forward of the net opening, significantly reducing currents and vibrations in the water directly preceding the net. This system was effective in collecting larvae representing more than 25 species of fish at sampling depths ranging from surface to 10 m and could easily be used at greater depths.

  13. AREVA net income: 649 million euros

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-03-15

    This document presents the financial statements for 2006 of Areva group: net income: 649 million euros; backlog up by 24.6% to 25.6 billion euros; steady growth of sales revenue: + 7.3%1 to 10.863 billion euros; operating income of 407 million euros: excellent divisional performance and constitution of a significant provision for the OL3 project in Finland; dividend proposed to Annual General Meeting of Shareholders: 8.46 euros per share.

  14. AREVA net income: 649 million euros

    International Nuclear Information System (INIS)

    2007-03-01

    This document presents the financial statements for 2006 of Areva group: net income: 649 million euros; backlog up by 24.6% to 25.6 billion euros; steady growth of sales revenue: + 7.3%1 to 10.863 billion euros; operating income of 407 million euros: excellent divisional performance and constitution of a significant provision for the OL3 project in Finland; dividend proposed to Annual General Meeting of Shareholders: 8.46 euros per share

  15. Master Robotic Net

    Directory of Open Access Journals (Sweden)

    Vladimir Lipunov

    2010-01-01

    Full Text Available The main goal of the MASTER-Net project is to produce a unique fast sky survey with all sky observed over a single night down to a limiting magnitude of 19-20. Such a survey will make it possible to address a number of fundamental problems: search for dark energy via the discovery and photometry of supernovae (including SNIa, search for exoplanets, microlensing effects, discovery of minor bodies in the Solar System, and space-junk monitoring. All MASTER telescopes can be guided by alerts, and we plan to observe prompt optical emission from gamma-ray bursts synchronously in several filters and in several polarization planes.

  16. Limitations of shallow nets approximation.

    Science.gov (United States)

    Lin, Shao-Bo

    2017-10-01

    In this paper, we aim at analyzing the approximation abilities of shallow networks in reproducing kernel Hilbert spaces (RKHSs). We prove that there is a probability measure such that the achievable lower bound for approximating by shallow nets can be realized for all functions in balls of reproducing kernel Hilbert space with high probability, which is different with the classical minimax approximation error estimates. This result together with the existing approximation results for deep nets shows the limitations for shallow nets and provides a theoretical explanation on why deep nets perform better than shallow nets. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Shielding calculations for NET

    International Nuclear Information System (INIS)

    Verschuur, K.A.; Hogenbirk, A.

    1991-05-01

    In the European Fusion Technology Programme there is only a small activity on research and development for fusion neutronics. Never-the-less, looking further than blanket design now, as ECN is getting involved in design of radiation shields for the coils and biological shields, it becomes apparent that fusion neutronics as a whole still needs substantial development. Existing exact codes for calculation of complex geometries like MCNP and DORT/TORT are put over the limits of their numerical capabilities, whilst approximate codes for complex geometries like FURNACE and MERCURE4 are put over the limits of their modelling capabilities. The main objective of this study is just to find out how far we can get with existing codes in obtaining reliable values for the radiation levels inside and outside the cryostat/shield during operation and after shut-down. Starting with a 1D torus model for preliminary parametric studies, more dimensional approximation of the torus or parts of it including the main heterogeneities should follow. Regular contacts with the NET-Team are kept, to be aware of main changes in NET design that might affect our calculation models. Work on the contract started 1 July 1990. The technical description of the contract is given. (author). 14 refs.; 4 figs.; 1 tab

  18. AB stacked few layer graphene growth by chemical vapor deposition on single crystal Rh(1 1 1) and electronic structure characterization

    International Nuclear Information System (INIS)

    Kordatos, Apostolis; Kelaidis, Nikolaos; Giamini, Sigiava Aminalragia; Marquez-Velasco, Jose; Xenogiannopoulou, Evangelia; Tsipas, Polychronis; Kordas, George; Dimoulas, Athanasios

    2016-01-01

    Highlights: • Growth of non-defective few layer graphene on Rh(1 1 1) substrates using an ambient- pressure CVD method. • Control of graphene stacking order via the cool-down rate. • Graphene is grown with a mainly AB-stacking geometry on single-crystalline Rhodium for a slow cool-down rate and non-AB for a very fast cool-down. • Good epitaxial orientation of the surface is presented through the RHEED data and confirmed with ARPES characterization for the lower cool-down rate, where graphene's ΓK direction a perfectly aligned with the ΓK direction of the Rh(1 1 1) single crystal. - Abstract: Graphene synthesis on single crystal Rh(1 1 1) catalytic substrates is performed by Chemical Vapor Deposition (CVD) at 1000 °C and atmospheric pressure. Raman analysis shows full substrate coverage with few layer graphene. It is found that the cool-down rate strongly affects the graphene stacking order. When lowered, the percentage of AB (Bernal) -stacked regions increases, leading to an almost full AB stacking order. When increased, the percentage of AB-stacked graphene regions decreases to a point where almost a full non AB-stacked graphene is grown. For a slow cool-down rate, graphene with AB stacking order and good epitaxial orientation with the substrate is achieved. This is indicated mainly by Raman characterization and confirmed by Reflection high-energy electron diffraction (RHEED) imaging. Additional Scanning Tunneling Microscopy (STM) topography data confirm that the grown graphene is mainly an AB-stacked structure. The electronic structure of the graphene/Rh(1 1 1) system is examined by Angle resolved Photo-Emission Spectroscopy (ARPES), where σ and π bands of graphene, are observed. Graphene's ΓK direction is aligned with the ΓK direction of the substrate, indicating no significant contribution from rotated domains.

  19. Growth kinetics for temperature-controlled atomic layer deposition of GaN using trimethylgallium and remote-plasma-excited NH3

    Science.gov (United States)

    Pansila, P.; Kanomata, K.; Miura, M.; Ahmmad, B.; Kubota, S.; Hirose, F.

    2015-12-01

    Fundamental surface reactions in the atomic layer deposition of GaN with trimethylgallium (TMG) and plasma-excited NH3 are investigated by multiple-internal-reflection infrared absorption spectroscopy (MIR-IRAS) at surface temperatures varying from room temperature (RT) to 400 °C. It is found that TMG is saturated at RT on GaN surfaces when the TMG exposure exceeds 8 × 104 Langmuir (L), where 1 L corresponds to 1.33 × 10-4 Pa s (or 1.0 × 10-6 Torr s), and its saturation density reaches the maximum value at RT. Nitridation with the plasma-excited NH3 on the TMG-saturated GaN surface is investigated by X-ray photoelectron spectroscopy (XPS). The nitridation becomes effective at surface temperatures in excess of 100 °C. The reaction models of TMG adsorption and nitridation on the GaN surface are proposed in this paper. Based on the surface analysis, a temperature-controlled ALD process consisting of RT-TMG adsorption and nitridation at 115 °C is examined, where the growth per cycle of 0.045 nm/cycle is confirmed. XPS analysis indicates that all N atoms are bonded as GaN. Atomic force microscopy indicates an average roughness of 0.23 nm. We discuss the reaction mechanism of GaN ALD in the low-temperature region at around 115 °C with TMG and plasma-excited NH3.

  20. Metalorganic chemical vapor deposition growth and thermal stability of the AlInN/GaN high electron mobility transistor structure

    International Nuclear Information System (INIS)

    Yu, Hongbo; Ozturk, Mustafa; Demirel, Pakize; Cakmak, Huseyin; Bolukbas, Basar; Caliskan, Deniz; Ozbay, Ekmel

    2011-01-01

    The Al x In 1−x N barrier high electron mobility transistor (HEMT) structure has been optimized with varied barrier composition and thickness grown by metalorganic chemical vapor deposition. After optimization, a transistor structure comprising a 7 nm thick nearly lattice-matched Al 0.83 In 0.17 N barrier exhibits a sheet electron density of 2.0 × 10 13 cm −2 with a high electron mobility of 1540 cm 2 V −1 s −1 . An Al 0.83 In 0.17 N barrier HEMT device with 1 µm gate length provides a current density of 1.0 A mm −1 at V GS = 0 V and an extrinsic transconductance of 242 mS mm −1 , which are remarkably improved compared to that of a conventional Al 0.3 Ga 0.7 N barrier HEMT. To investigate the thermal stability of the HEMT epi-structures, post-growth annealing experiments up to 800 °C have been applied to Al 0.83 In 0.17 N and Al 0.3 Ga 0.7 N barrier heterostructures. As expected, the electrical properties of an Al 0.83 In 0.17 N barrier HEMT structure showed less stability than that of an Al 0.3 Ga 0.7 N barrier HEMT to the thermal annealing. The structural properties of Al 0.83 In 0.17 N/GaN also showed more evidence for decomposition than that of the Al 0.3 Ga 0.7 N/GaN structure after 800 °C post-annealing