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Sample records for composite films grown

  1. Composition of MBE-grown iron oxide films

    NARCIS (Netherlands)

    Voogt, F.C; Hibma, T; Smulders, P.J M; Niesen, L

    A wide range of iron oxides have been grown epitaxially on MgO(100) substrates using a dual beam technique in which the deposited iron is oxidised by a beam of NO2 particles. At high fluxes magnetite (Fe3-deltaO4) phases with compositions between near-stoichiometric magnetite (Fe3O4, delta = 0) and

  2. Biocidal Silver and Silver/Titania Composite Films Grown by Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    D. W. Sheel

    2008-01-01

    Full Text Available This paper describes the growth and testing of highly active biocidal films based on photocatalytically active films of TiO2, grown by thermal CVD, functionally and structurally modified by deposition of nanostructured silver via a novel flame assisted combination CVD process. The resulting composite films are shown to be highly durable, highly photocatalytically active and are also shown to possess strong antibacterial behaviour. The deposition control, arising from the described approach, offers the potential to control the film nanostructure, which is proposed to be crucial in determining the photo and bioactivity of the combined film structure, and the transparency of the composite films. Furthermore, we show that the resultant films are active to a range of organisms, including Gram-negative and Gram-positive bacteria, and viruses. The very high-biocidal activity is above that expected from the concentrations of silver present, and this is discussed in terms of nanostructure of the titania/silver surface. These properties are especially significant when combined with the well-known durability of CVD deposited thin films, offering new opportunities for enhanced application in areas where biocidal surface functionality is sought.

  3. Biocidal Silver and Silver/Titania Composite Films Grown by Chemical Vapour Deposition

    OpenAIRE

    Sheel, DW; Brook, LA; Evans, P.; Foster, HA; Yates, HM; Steele, A; Ditta, IB

    2008-01-01

    This paper describes the growth and testing of highly active biocidal films based on photocatalytically active films of TiO2, grownby\\ud thermal CVD, functionally and structurallymodified by deposition of nanostructured silver via a novel flame assisted combination\\ud CVD process. The resulting composite films are shown to be highly durable, highly photocatalytically active and are also shown to\\ud possess strong antibacterial behaviour. The deposition control, arising from the described appr...

  4. Physical properties of nanostructured (PbSx(CuS1−x composite thin films grown by successive ionic layer adsorption and reaction method

    Directory of Open Access Journals (Sweden)

    A.U. Ubale

    2016-03-01

    Full Text Available Nanostructured ternary semiconducting (PbSx(CuS1−x thin films were grown on glass substrates by successive ionic layer adsorption and reaction (SILAR technique at room temperature. The structural, morphological and optical characterizations of the films were carried out by X-ray diffraction, scanning electron microscopy and UV–Vis spectrophotometer respectively. The structural studies revealed that, (PbSx(CuS1−x films are nanocrystalline in nature and have mixed phase of cubic PbS and hexagonal CuS. The optical absorption measurements showed that band gap energy of (PbSx(CuS1−x can be engineered between 2.57 and 2.28 eV by varying compositional parameter ‘x’. The room temperature dc dark electrical resistivity of PbS film is found to be 28.85 Ωcm and it decreases when content of Cu in composite increases and becomes 0.05 Ωcm for pure CuS. The thermo-emf measurements showed that the as deposited (PbSx(CuS1−x films are of n-type. The water angle contact measurements of (PbSx(CuS1−x, revealed that, films are hydrophilic in nature and it could be advantageous in electrochemical application.

  5. Effects of lithium (Li) on lithium-cuprous-oxide (Li-Cu2O) composite films grown by using electrochemical deposition for a PEC photoelectrode

    Science.gov (United States)

    Kim, Tae Gyoum; Ryu, Hyukhyun; Lee, Won-Jae

    2016-01-01

    In this study, Li-Cu2O composite films were grown on fluorine-doped tin-oxide (FTO) substrates by using the electrochemical deposition method. Various amounts of lithium (Li) were added to grow the Li-Cu2O composite films. We analyzed the morphology, structure, photocurrent density and photo-stability of the Li-Cu2O composite films by using various measurements such as field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and potentiostat/galvanostat measurements, respectively. As a result, the highest XRD Cu2O (111)/ LiO (011) peak intensity ratio was obtained for the 10-wt% sample, which also had the highest photocurrent density value of -5.00 mA/cm2. The highest photocurrent density value for the 10-wt% sample was approximately 5 times greater than that of the 0-wt% sample. As shown by this result, we found that adding Li could improve the photocurrent values of Li-Cu2O composite films.

  6. Optoelectronic properties, structure and composition of a-SiC:H films grown in undiluted and H{sub 2} diluted silane-methane plasma

    Energy Technology Data Exchange (ETDEWEB)

    Desalvo, A. [Dipartimento di Chimica Applicata e Scienza dei Materiali, Facolta di Ingegneria, Universita di Bologna, v.le Risorgimento 2, I-40136 Bologna (Italy); Giorgis, F.; Pirri, C.F.; Tresso, E. [Dipartimento di Fisica ed Unita INFM del Politecnico di Torino, C.so Duca degli Abruzzi 24, I-10129 Torino (Italy); Rava, P. [Elettrorava S.p.A., Via Don Sapino 176, I-10040 Savonera, Torino (Italy); Galloni, R.; Rizzoli, R.; Summonte, C. [CNR-Istituto LAMEL, Via Gobetti 101, I-40129 Bologna, Italy I-40129 Torino (Italy)

    1997-06-01

    a-SiC:H films with energy gap in the range 2.00{endash}2.65 eV have been grown by plasma enhanced chemical vapor deposition in undiluted and H{sub 2} diluted SiH{sub 4}+CH{sub 4} gas mixtures, by making use of optimized deposition conditions. A complete picture of structural, compositional, optoelectronic, and defective properties for high quality films has been drawn for the first time. We show that the addition of H{sub 2} to the gas mixture leads to a different chemical composition of the deposited films; in particular, carbon incorporation is enhanced and a carbon fraction in the solid matrix up to C/(C+Si){approx}0.45 can be obtained. These films have a higher mass density, a reduced microvoid and carbon cluster concentration, a better structural connectivity, and improved optoelectronic properties. For samples with optical gap below 2.4 eV, the reduced defect concentration of H{sub 2} diluted films results in an increase of the photoconductivity gain and the steady-state ({eta}{mu}{tau}){sub ss} values up to two orders of magnitude. {copyright} {ital 1997 American Institute of Physics.}

  7. PLD-grown thin film saturable absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Tellkamp, Friedjof

    2012-11-01

    The subject of this thesis is the preparation and characterization of thin films made of oxidic dielectrics which may find their application as saturable absorber in passively Q-switched lasers. The solely process applied for fabrication of the thin films was the pulsed laser deposition (PLD) which stands out against other processes by its flexibility considering the composition of the systems to be investigated. Within the scope of this thesis the applied saturable absorbers can be divided into two fundamentally different kinds of functional principles: On the one hand, saturable absorption can be achieved by ions embedded in a host medium. Most commonly applied bulk crystals are certain garnets like YAG (Y{sub 3}Al{sub 5}O{sub 12}) or the spinel forsterite (Mg{sub 2}SiO{sub 4}), in each case with chromium as dopant. Either of these media was investigated in terms of their behavior as PLD-grown saturable absorber. Moreover, experiments with Mg{sub 2}GeO{sub 4}, Ca{sub 2}GeO{sub 4}, Sc{sub 2}O{sub 3}, and further garnets like YSAG or GSGG took place. The absorption coefficients of the grown films of Cr{sup 4+}:YAG were determined by spectroscopic investigations to be one to two orders of magnitude higher compared to commercially available saturable absorbers. For the first time, passive Q-switching of a Nd:YAG laser at 1064 nm with Cr{sup 4+}:YAG thin films could be realized as well as with Cr:Sc{sub 2}O{sub 3} thin films. On the other hand, the desirable effect of saturable absorption can also be generated by quantum well structures. For this purpose, several layer system like YAG/LuAG, Cu{sub 2}O/MgO, and ZnO/corumdum were investigated. It turned out that layer systems with indium oxide (In{sub 2}O{sub 3}) did not only grew in an excellent way but also showed up a behavior regarding their photo luminescence which cannot be explained by classical considerations. The observed luminescence at roughly 3 eV (410 nm) was assumed to be of excitonic nature and its

  8. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  9. Composition dependence of the ferroelectric properties of lanthanum-modified bismuth titanate thin films grown by using pulsed-laser deposition

    CERN Document Server

    Bu, S D; Park, B H; Noh, T W

    2000-01-01

    Lanthanum-modified bismuth titanate, Bi sub 4 sub - sub x La sub x Ti sub 3 O sub 1 sub 2 (BLT), thin films with a La concentration of 0.25<=x<=1.00 were grown on Pt/Ti/SiO sub 2 /Si substrates by using pulsed-laser deposition. The BLT films showed well-saturated polarization-electric field curves whose remnant polarizations were 16.1 mu C/cm sup 2 , 27.8 mu C/cm sup 2 , 19.6 mu C/cm sup 2 , and 2.7 mu C/cm sup 2 , respectively, for x=0.25, 0.05, 0.75, and 1.00. The fatigue characteristics became better with increasing x up to 0.75. The Au/BLT/Pt capacitor with a La concentration of 0.50 showed an interesting dependence of the remanent polarization on the number of repetitive read/write cycles. On the other hand, the capacitor with a La concentration of 0.75 showed fatigue-free characteristics.

  10. Enhanced magnetization and anisotropy in Mn-Ga thin films grown on LSAT

    Science.gov (United States)

    Karel, J.; Casoli, F.; Nasi, L.; Lupo, P.; Sahoo, R.; Ernst, B.; Markou, A.; Kalache, A.; Cabassi, R.; Albertini, F.; Felser, C.

    2017-10-01

    Epitaxial thin films of MnxGa1-x (x = 0.70, 0.74) grown on single crystal (LaAlO3)0.3(Sr2TaAlO6)0.7 [LSAT] substrates exhibit an enhanced magnetic moment and magnetic anisotropy in comparison to films of the same composition grown epitaxially on SrTiO3 [STO] single crystal substrates. Atomic and magnetic force microscopy revealed films exhibiting uniform grains and magnetic domain structures, with only minor differences between the films grown on different substrates. High resolution transmission electron microscopy on the x = 0.74 sample grown on LSAT showed a well-ordered, faceted film structure with the tetragonal c-axis oriented out of the film plane. Further, misfit dislocations, accommodating the lattice mismatch, were evidenced at the film/substrate interface. The out of plane c lattice parameter is larger for all x in the films grown on LSAT, due to the smaller substrate lattice parameter compared to STO. The increase in c generates a larger distortion of the tetragonal lattice which promotes the enhanced magnetization and magnetocrystalline anisotropy. These results indicate that LSAT is a promising substrate for realizing highly tailored magnetic properties for future spintronic applications not only in MnxGa1-x but also in the broader class of tetragonal Mn-Z-Ga (Z = transition metal) materials.

  11. Cuprous oxide thin films grown by hydrothermal electrochemical deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Majumder, M., E-mail: mousumi@cgcri.res.in; Biswas, I.; Pujaru, S.; Chakraborty, A.K.

    2015-08-31

    Semiconducting cuprous oxide films were grown by a hydrothermal electro-deposition technique on metal (Cu) and glass (ITO) substrates between 60 °C and 100 °C. X-ray diffraction studies reveal the formation of cubic cuprous oxide films in different preferred orientations depending upon the deposition technique used. Film growth, uniformity, grain size, optical band gap and photoelectrochemical response were found to improve in the hydrothermal electrochemical deposition technique. - Highlights: • Cu{sub 2}O thin films were grown on Cu and glass substrates. • Conventional and hydrothermal electrochemical deposition techniques were used. • Hydrothermal electrochemical growth showed improved morphology, thickness and optical band gap.

  12. Determination via luminescence spectroscopy and x-ray diffraction of the strain and composition of GaN and Al(x)Ga(1-x)N thin films grown on 6H-SiC(0001) substrates

    Science.gov (United States)

    Perry, William George

    1997-12-01

    This dissertation describes the luminescence and x-ray diffraction characterization of GaN and AlxGa1-xN thin films that were deposited on 6H-SiC(0001) substrates. These materials have applications for optoelectronic devices that are operational in the UV to green regions of the spectrum and for high-temperature, high-frequency and high-power microelectronic devices. The primary tools used in this research were photoluminescence and cathodoluminescence spectroscopies and high-resolution x-ray diffraction. Biaxial strains resulting from the mismatches in thermal expansion coefficients and lattice parameters in GaN films grown on AlN buffer layers previously deposited on vicinal and on-axis 6H-SiC(0001) substrates were measured using photoluminescence. A linear relationship between the bound exciton energy (EBX) and the biaxial strain along the c-axis direction was observed. A marked variation in the biaxial strain in GaN films deposited on off- and on-axis SiC was determined. It was attributed to the difference in the density and nature of the microstructural defects that originate at the steps on the SiC surface. The strain in the GaN films was either in tension or compression; whereas, only tensile strains were reported in all previous studies using SiC wafers. This indicated that the lattice mismatch strain in the former films was not fully relieved by defect formation. This result was confirmed by the observation via HRTEM of a 0.9% residual compressive strain at the GaN/AlN interface. Cathodoluminescence was used to determine the optical spectra in AlxGa1-xN films over the entire composition range of x. A bowing parameter of b = 1.65 eV for the bound exciton peak was observed. This bound exciton peak became more localized as the Al mole fraction increased. This was attributed to the increase in the ionization energy (ED) of the donor to which the exciton was bound. The donor-acceptor pair (DAP) band and the so-called 'yellow' emission band that are commonly

  13. PLD Grown Polycrystalline Tungsten Disulphide (WS2 Films

    Directory of Open Access Journals (Sweden)

    Salman Alfihed

    2013-01-01

    Full Text Available Polycrystalline WS2 films were grown by pulsed laser deposition (PLD system at relatively low temperature. The main objective of this study is to optimize the growth conditions for polycrystalline WS2 films at relatively low temperature to use them for photovoltaics (PVs. Different growth conditions and substrates are used and examined systematically. It is found out that films grown on strontium titanate SrTiO3 (STO substrate have the best structural properties when compared to other substrates examined in this work. X-ray diffraction and optical characterizations of these films reveal crystallographic growth and very promising optical properties for PVs. Furthermore, it was observed that higher growth temperature (>300°C has an unfavorable effect on the layers by creating some tungsten metallic droplets.

  14. Morphology and photoresponse of crystalline antimony film grown on mica by physical vapor deposition

    Directory of Open Access Journals (Sweden)

    Shafa Muhammad

    2016-09-01

    Full Text Available Antimony is a promising material for the fabrication of photodetectors. This study deals with the growth of a photosensitive thin film by the physical vapor deposition (PVD of antimony onto mica surface in a furnace tube. The geometry of the grown structures was studied via scanning electron microscopy (SEM, X-ray diffraction (XRD, energy-dispersive X-ray spectroscopy (EDX and elemental diffraction analysis. XRD peaks of the antimony film grown on mica mostly matched with JCPDF Card. The formation of rhombohedral crystal structures in the film was further confirmed by SEM micrographs and chemical composition analysis. The Hall measurements revealed good electrical conductivity of the film with bulk carrier concentration of the order of 1022 Ω·cm-3 and mobility of 9.034 cm2/Vs. The grown film was successfully tested for radiation detection. The photoresponse of the film was evaluated using its current-voltage characteristics. These investigations revealed that the photosensitivity of the antimony film was 20 times higher than that of crystalline germanium.

  15. Friction and wear performance of diamondlike carbon films grown in various source gas plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Nilufer, I. B.; Eryilmaz, O. L.; Beschliesser, M.; Fenske, G. R.

    2000-01-18

    In this study, the authors investigated the effects of various source gases (methane, ethane, ethylene, and acetylene) on the friction and wear performance of diamondlike carbon (DLC) films prepared in a plasma enhanced chemical vapor deposition (PECVD) system. Films were deposited on AISI H13 steel substrates and tested in a pin-on-disk machine against DLC-coated M50 balls in dry nitrogen. They found a close correlation between friction coefficient and source gas composition. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios exhibited lower friction coefficients and higher wear resistance than films grown in source gases with lower hydrogen-to-carbon (H/C) ratios. The lowest friction coefficient (0.014) was achieved with a film derived from methane with an WC ratio of 4, whereas the coefficient of films derived from acetylene (H/C = 1) was of 0.15. Similar correlations were observed for wear rates. Specifically, films derived from gases with lower H/C values were worn out and the substrate material was exposed, whereas films from methane and ethane remained intact and wore at rates that were nearly two orders of magnitude lower than films obtained from acetylene.

  16. Friction and wear performance of diamond-like carbon films grown in various source gas plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Nilufer, I.B.; Eryilmaz, O.L.; Beschliesser, M.; Fenske, G.R. [Argonne National Lab., IL (United States). Energy Technology Div.

    1999-11-01

    In this study, we investigated the effects of various source gases (methane, ethane, ethylene, and acetylene) on the friction and wear performance of diamond-like carbon (DLC) films prepared in a plasma-enhanced chemical vapor deposition (PECVD) system. Films were deposited on AISI H13 steel substrates and tested in a pin-on-disk machine against DLC-coated M50 balls in dry nitrogen. We found a close correlation between friction coefficient and source gas composition. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios exhibited lower friction coefficients and a higher wear resistance than films grown in source gases with lower hydrogen-to-carbon (H/C) ratios. The lowest friction coefficient (0.014) was achieved with a film derived from methane with an H/C ratio of 4, whereas the coefficient of films derived from acetylene (H/C=1) was 0.15. Similar correlations were observed for wear rates. Specifically, films derived from gases with lower H/C values were worn out, and the substrate material was exposed, whereas films from methane and ethane remained intact and wore at rates that were almost two orders of magnitude lower than films obtained from acetylene. (orig.)

  17. Chitosan composite films. Biomedical applications.

    Science.gov (United States)

    Cárdenas, Galo; Anaya, Paola; von Plessing, Carlos; Rojas, Carlos; Sepúlveda, Jackeline

    2008-06-01

    Chitosan acetate films have been prepared using chitosans from shrimps (Pleuroncodes monodon) of low and high molecular weight (LMv = 68,000 g/mol and HMv = 232,000 g/mol) and deacetylation degree of 80 and 100%, respectively. The chitosan films were obtained by addition of several additives to acetic acid chitosan solutions, such as: glycerol, oleic acid and linoleic acid in different proportions. The pH of the solutions before casting ranged from 5.0 to 6.0. The composite film thickness are reported. The films have been analyzed by FTIR showing characteristic bands corresponding to the additives. The scanning electron microscopy (SEM) studies reveals the different morphology of the composite films. The films exhibit different physical properties depending upon the additives and/or mixture of them. The addition of glycerol to composite improves the elasticity of the films. The swelling in glucose and saline solutions for several films was evaluated, being higher in the glucose solution. The bactericide test against Staphylococcus aureus, Pseudomona aeruginosa and Acinetobacter baumanii in plates with either blood and or agar tripticase showed that the molecular weight influences on the bactericidal properties of the chitosan composite films and over its effect against gram positive and gram negative bacteria. Medical applications of the composite films were done in patients with burns, ulcers and injuries, the films containing glycerol showed good adhesion in comparison with those without it. The composite films tested were mainly three (1) chitosan acetate with glycerol, (2) chitosan acetate with oleic acid and (3) chitosan acetate with glycerol and oleic acid. Excellent results in the skin recovery were obtained after 7-10 days. Since the chitosan is biodegradable by the body enzymes it does not need to be removed and increases the gradual grows of the damage tissues.

  18. Thermally grown thin nitride films as a gate dielectric

    CERN Document Server

    Shin, H C; Hwang, T K; Lee, K R

    1998-01-01

    High-quality very thin films ( <=6 nm) of silicon nitride were thermally grown in ammonia atmosphere with an IR (Infrared) gold image furnace. As-grown nitride film was analyzed using AES(Auger Emission Spectroscopy). Using MIS (Metal-Insulator-Semiconductor) devices, the growth rate was calculated using CV (Capacitance-Voltage) measurements and various electrical characteristics were obtained using CV, IV (Current-Voltage), trapping, time-dependent breakdown, high-field stress, constant current injection stress and dielectric breakdown techniques. These characteristics showed that very thin thermal silicon nitride films can be used as gate dielectrics for future highly scaled-down ULSI (Ultra Large Scale Integrated) devices, especially for EEPROM (Electrically Erasable and Programmable ROM)'s.

  19. Effect of deposition temperature on the properties of sputtered YIG films grown on quartz

    Energy Technology Data Exchange (ETDEWEB)

    Roumie, M., E-mail: mroumie@cnrs.edu.lb [Accelerator Laboratory, Lebanese Atomic Energy Commission, National Council for Scientific Research, Airport Road, P.O. Box 11-8281, Beirut (Lebanon); Samad, B. Abdel [DIOM Laboratory, Jean Monnet University, 23 rue du Docteur Paul Michelon, Saint-Etienne 42023 (France); Tabbal, M.; Abi-Akl, M. [Department of Physics, American University of Beirut, Bliss Street, P.O. Box 11-0236, Beirut (Lebanon); Blanc-Mignon, M.-F. [DIOM Laboratory, Jean Monnet University, 23 rue du Docteur Paul Michelon, Saint-Etienne 42023 (France); Nsouli, B. [Accelerator Laboratory, Lebanese Atomic Energy Commission, National Council for Scientific Research, Airport Road, P.O. Box 11-8281, Beirut (Lebanon)

    2010-11-01

    Yttrium Iron Garnet (YIG), Y{sub 3}Fe{sub 5}O{sub 12}, is an oxide material that has potential applications in the magneto-optical recording media and microwave device industries. These materials, when synthesized in thin film form, usually require post-deposition annealing in order to enhance their physical properties. Furthermore, integration of YIG based optical components requires the synthesis of high quality YIG material on quartz, a process that may be problematic due to poor adhesion and lattice mismatch. Thus, we have conducted a study on the effect of deposition temperature (from 25 to 800 deg. C) and post-deposition annealing (at 740 deg. C) on the crystalline quality and chemical composition of YIG thin films, grown by radio-frequency magnetron sputtering, on quartz substrates. X-ray diffraction (XRD) shows that as-grown layers are amorphous, and subsequent annealing is necessary to induce film crystallization. Rutherford backscattering spectrometry analyses were also conducted and the chemical composition of the films was found to depend on initial deposition temperature and is affected by post-deposition anneals. Comparison of the XRD and RBS results point out to the existence of an optimal deposition temperature at about 700 deg. C for the formation of high crystalline quality and stoichiometric YIG thin films. Magnetic measurements were found to correlate to the XRD and RBS analyses.

  20. Preparation and chemical characterization of neodymium-doped molybdenum oxide films grown using spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Alfonso, J. E. [Universidad Nacional de Colombia, Departamento de Fisica, Grupo de Ciencia Materiales y Superficies, AA 5997 Bogota DC (Colombia); Moreno, L. C., E-mail: jealfonsoo@unal.edu.co [Universidad Nacional de Colombia, Departamento de Quimica, AA 5997 Bogota DC (Colombia)

    2014-07-01

    We studied the crystalline, morphology, and surface composition of Nd-doped molybdenum oxide films grown on glass slides through spray pyrolysis. After fabrication, the films were subjected to thermal treatment in oxygen for periods ranging from 2 to 20 hours. The films were structurally characterized though X-ray diffraction (XRD), their bulk chemical composition was determined using Energy-Dispersive X-ray analysis (EDX), and their surface composition was determined using X-ray Photoelectron Spectroscopy (XP S). The XRD results show that the films obtained from different dissolution volumes and at substrate temperature of 300 grades C exhibit the characteristics of the oxygen-deficient molybdenum trioxide Mo{sub 9}O{sub 26} phase. The films subjected to different thermal treatments exhibit a mixture of Mo{sub 9}O{sub 26} and Mo{sub 17}O{sub 47} phases. EDX study shows the energy belonging to the L line of Nd. Finally, films doped with Nd and subjected to a thermal treatment of 20 h were analyzed through XP S, showing the binding energies at the crystalline lattice correspond to Nd{sub 2} (MoO{sub 4}){sub 3} and Nd{sub 2}Mo{sub 2}O{sub 7}. (Author)

  1. Peeling off effects in vertically aligned Fe3C filled carbon nanotubes films grown by pyrolysis of ferrocene

    Science.gov (United States)

    Boi, Filippo S.; Medranda, Daniel; Ivaturi, Sameera; Wang, Jiayu; Guo, Jian; Lan, Mu; Wen, Jiqiu; Wang, Shanling; He, Yi; Mountjoy, Gavin; Willis, Maureen A. C.; Xiang, Gang

    2017-06-01

    We report the observation of an unusual self-peeling effect which allows the synthesis of free standing vertically aligned carbon nanotube films filled with large quantities of Fe3C and small quantities of γ-Fe crystals. We demonstrate that this effect depends on the interplay of three main factors: (1) the physical interactions between the chosen substrate surface and grown carbon nanotubes (CNTs), which is fixed by the composition of the used substrate (111 SiO2/Si or quartz), (2) the CNT-CNT Van der Waals interactions, and (3) the differential thermal contraction between the grown CNT film and the used substrate, which is fixed by the cooling rate differences between the grown film and the used quartz or Si/SiO2 substrates. The width and stability of these films are then further increased to cm-scale by addition of small quantities of toluene to the ferrocene precursor.

  2. Growth and properties of ZnO films grown by the ultrasonic spray-assisted CVD.

    Science.gov (United States)

    Wang, Aiji; Chen, He; Chen, Tingfang; Wu, Zhenglong; Li, Yongliang; Wang, Yinshu

    2014-05-01

    ZnO films were successfully grown on the glass substrates employing an ultrasonic spray-assisted CVD method at 573-673 K. The optical properties, electrical characteristics and crystalline structures of the films were characterized. Effects of the growth temperatures on the film properties were studied. The film growth mode, morphology, transmittance, conductivity and emission properties are very sensitive to the growth temperatures. Growing at lower temperatures would improve both the preferential growth along c-axis and smoothness of the films. The conductivity and transmittance of the films grown at 573 K are also superior to that grown at higher temperatures. All films exhibit strong emission in the visible region and weak emission in UV region. However, the relative intensity of the UV emission to visible emission of the film grown at 573 K is obviously stronger than that grown at higher temperatures.

  3. Mineral composition of organically grown tomato

    Science.gov (United States)

    Ghambashidze, Giorgi

    2014-05-01

    In recent years, consumer concerns on environmental and health issues related to food products have increased and, as a result, the demand for organically grown production has grown. Results indicate that consumers concerned about healthy diet and environmental degradation are the most likely to buy organic food, and are willing to pay a high premium. Therefore, it is important to ensure the quality of the produce, especially for highly consumed products. The tomato (Lycopersicon esculentum) is one of the most widely consumed fresh vegetables in the world. It is also widely used by the food industries as a raw material for the production of derived products such as purees or ketchup. Consequently, many investigations have addressed the impact of plant nutrition on the quality of tomato fruit. The concentrations of minerals (P, Na, K, Ca and Mg) and trace elements (Cu, Zn and Mn) were determined in tomatoes grown organically in East Georgia, Marneuli District. The contents of minerals and Mn seem to be in the range as shown in literature. Cu and Zn were found in considerably high amounts in comparison to maximum permissible values established in Georgia. Some correlations were observed between the minerals and trace elements studied. K and Mg were strongly correlated with Cu and Zn. Statistically significant difference have shown also P, K and Mg based between period of sampling.

  4. Method of fabricating low-dislocation-density epitaxially-grown films with textured surfaces

    Science.gov (United States)

    Li, Qiming; Wang, George T

    2015-01-13

    A method for forming a surface-textured single-crystal film layer by growing the film atop a layer of microparticles on a substrate and subsequently selectively etching away the microparticles to release the surface-textured single-crystal film layer from the substrate. This method is applicable to a very wide variety of substrates and films. In some embodiments, the film is an epitaxial film that has been grown in crystallographic alignment with respect to a crystalline substrate.

  5. As-grown enhancement of spinodal decomposition in spinel cobalt ferrite thin films by Dynamic Aurora pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, Nipa [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Physics, Jagannath University, Dhaka 1100 (Bangladesh); Kawaguchi, Takahiko; Kumasaka, Wataru [Department of Electronics and Materials Science, Shizuoka University, Hamamatsu 432-8561 (Japan); Das, Harinarayan [Materials Science Division, Atomic Energy Centre, Dhaka 1000 (Bangladesh); Shinozaki, Kazuo [School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8550 (Japan); Sakamoto, Naonori [Department of Electronics and Materials Science, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan); Suzuki, Hisao [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Electronics and Materials Science, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan); Wakiya, Naoki, E-mail: wakiya.naoki@shizuoka.ac.jp [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Electronics and Materials Science, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan)

    2017-06-15

    Highlights: • As-grown enhancement of spinodal decomposition (SD) in Co{sub x}Fe{sub 3−x}O{sub 4} film is observed. • Magnetic-field-induced ion-impingement enhances SD without any post-annealing. • The enhancement of SD is independent of the lattice-mismatch-induced strain. • This approach can promote SD in any thin film without post-deposition annealing. - Abstract: Cobalt ferrite Co{sub x}Fe{sub 3−x}O{sub 4} thin films with composition within the miscibility gap were grown using Dynamic Aurora pulsed laser deposition. X-ray diffraction patterns reveal as-grown phase separation to Fe-rich and Co-rich phases with no post-deposition annealing. The interconnected surface microstructure of thin film shows that this phase separation occurs through spinodal decomposition enhanced by magnetic-field-induced ion-impingement. The lattice parameter variation of the thin films with the magnetic field indicates that the composition fluctuations can be enhanced further by increasing the magnetic field. Results show that spinodal decomposition enhancement by magnetic-field-induced ion-impingement is independent of the lattice-mismatch-induced strain. This approach can promote spinodal decomposition in any thin film with no post-deposition annealing process.

  6. Diamond structures grown from polymer composite nanofibers

    Czech Academy of Sciences Publication Activity Database

    Potocký, Štěpán; Kromka, Alexander; Babchenko, Oleg; Rezek, Bohuslav; Martinová, L.; Pokorný, P.

    2013-01-01

    Roč. 5, č. 6 (2013), s. 519-521 ISSN 2164-6627 R&D Projects: GA ČR GAP108/12/0910; GA ČR GAP205/12/0908 Institutional support: RVO:68378271 Keywords : chemical vapour deposition * composite polymer * nanocrystalline diamond * nanofiber sheet * SEM Subject RIV: BM - Solid Matter Physics ; Magnetism

  7. Anisotropic magnetothermopower in ferromagnetic thin films grown on macroscopic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jayathilaka, P.B. [Department of Physical Sciences, Faculty of Applied Sciences, Rajarata University of Sri Lanka, Mihintale (Sri Lanka); Belyea, D.D. [Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Fawcett, T.J. [College of Engineering, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Miller, Casey W. [School of Chemistry and Materials Science, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623 (United States)

    2015-05-15

    We report observing the anisotropic magnetothermopower in a variety of ferromagnetic thin films grown on macroscopic substrates. These measurements were enabled by eliminating spurious signals related to the Anomalous Nernst Effect by butt-mounting the sample to the heat source and sink, and appropriate positioning of electrical contacts to avoid unwanted thermal gradients. This protocol enabled detailed measurements of the magnetothermopower in the transverse and longitudinal configurations. This may enable Spin Seebeck Effect studies in the in-plane geometry. - Highlights: • Unintentional thermal gradients along surface normal mitigated via butt-mounting. • Longitudinal/transverse magnetothermopower measured on many systems. • Anomalous Nernst Effect reduced. • Importance of magnetic anisotropy identified with angle-dependent measurements.

  8. Ferromagnetic relaxation in LPE-grown Eu-Ga substituted yttrium iron garnet films

    Science.gov (United States)

    Rao, B. Uma Maheshwar; Mukhopadhyay, P.; Srivastava, C. M.

    1986-11-01

    The magnetization, geff and linewidth ΔH∥ and ΔH⊥ for liquid-phase-epitaxially grown thin films of EuxY3-xFe5-yGayO12 (0.2≤x≤1.2; y=1.0) have been investigated in the temperature range 85-420 K. ΔH versus temperature curves show maxima which occur at about the same temperature as that observed in bulk single crystals of EuIG, but the width of the curves is narrower in the LPE films. The temperature and composition dependence of geff and ΔH have been explained on the basis of the three sublattice model and a new relaxation mechanism based on anisotropic exchange.

  9. Nitrogen isotope composition of organically and conventionally grown crops.

    Science.gov (United States)

    Bateman, Alison S; Kelly, Simon D; Woolfe, Mark

    2007-04-04

    Authentic samples of commercially produced organic and conventionally grown tomatoes, lettuces, and carrots were collected and analyzed for their delta15N composition in order to assemble datasets to establish if there are any systematic differences in nitrogen isotope composition due to the method of production. The tomato and lettuce datasets suggest that the different types of fertilizer commonly used in organic and conventional systems result in differences in the nitrogen isotope composition of these crops. A mean delta15N value of 8.1 per thousand was found for the organically grown tomatoes compared with a mean value of -0.1 per thousand for those grown conventionally. The organically grown lettuces had a mean value of 7.6 per thousand compared with a mean value of 2.9 per thousand for the conventionally grown lettuces. The mean value for organic carrots was not significantly different from the mean value for those grown conventionally. Overlap between the delta15N values of the organic and conventional datasets (for both tomatoes and lettuces) means that it is necessary to employ a statistical methodology to try and classify a randomly analyzed "off the shelf" sample as organic/conventional, and such an approach is demonstrated. Overall, the study suggests that nitrogen isotope analysis could be used to provide useful "intelligence" to help detect the substitution of certain organic crop types with their conventional counterparts. However, delta15N analysis of a "test sample" will not provide unequivocal evidence as to whether synthetic fertilizers have been used on the crop but could, for example, in a situation when there is suspicion that mislabeling of conventionally grown crops as "organic" is occurring, be used to provide supporting evidence.

  10. Correlation of process parameters and properties of TiO2 films grown by ion beam sputter deposition from a ceramic target

    Science.gov (United States)

    Bundesmann, Carsten; Lautenschläge, Thomas; Spemann, Daniel; Finzel, Annemarie; Mensing, Michael; Frost, Frank

    2017-10-01

    The correlation between process parameters and properties of TiO2 films grown by ion beam sputter deposition from a ceramic target was investigated. TiO2 films were grown under systematic variation of ion beam parameters (ion species, ion energy) and geometrical parameters (ion incidence angle, polar emission angle) and characterized with respect to film thickness, growth rate, structural properties, surface topography, composition, optical properties, and mass density. Systematic variations of film properties with the scattering geometry, namely the scattering angle, have been revealed. There are also considerable differences in film properties when changing the process gas from Ar to Xe. Similar systematics were reported for TiO2 films grown by reactive ion beam sputter deposition from a metal target [C. Bundesmann et al., Appl. Surf. Sci. 421, 331 (2017)]. However, there are some deviations from the previously reported data, for instance, in growth rate, mass density and optical properties.

  11. Chemical and nutrient composition of tomato varieties grown in ...

    African Journals Online (AJOL)

    1997-09-06

    Sep 6, 1997 ... esculantum) grown in ligarulll. Bush, Money-maker, Maglope, Heinz and Italia tomato varieties were purchased at the red ripe sl:age of matur i(y frorn Nakasero market, Kampala and their pH, total soluble solids, total titratable acidity, proximate composition, vitamin (A and C) and mineral (sodium, ...

  12. Deposition and Characterization of CVD-Grown Ge-Sb Thin Film Device for Phase-Change Memory Application

    Directory of Open Access Journals (Sweden)

    C. C. Huang

    2012-01-01

    Full Text Available Germanium antimony (Ge-Sb thin films with tuneable compositions have been fabricated on SiO2/Si, borosilicate glass, and quartz glass substrates by chemical vapour deposition (CVD. Deposition takes place at atmospheric pressure using metal chloride precursors at reaction temperatures between 750 and 875°C. The compositions and structures of these thin films have been characterized by micro-Raman, scanning electron microscope (SEM with energy dispersive X-ray analysis (EDX and X-ray diffraction (XRD techniques. A prototype Ge-Sb thin film phase-change memory device has been fabricated and reversible threshold and phase-change switching demonstrated electrically, with a threshold voltage of 2.2–2.5 V. These CVD-grown Ge-Sb films show promise for applications such as phase-change memory and optical, electronic, and plasmonic switching.

  13. ZnTe thin films grown by electrodeposition technique on Fluorine Tin Oxide substrates

    Energy Technology Data Exchange (ETDEWEB)

    Skhouni, O. [Laboratoire LOAOS, Département de Physique, Université Hassan II, Faculté des Sciences et Techniques, Bd Yasmina, BP 145 Mohammedia (Morocco); El Manouni, A. [Departament de Física Aplicada-ETSED, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia (Spain); Laboratoire LOAOS, Département de Physique, Université Hassan II, Faculté des Sciences et Techniques, Bd Yasmina, BP 145 Mohammedia (Morocco); Mollar, M. [Departament de Física Aplicada-ETSED, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia (Spain); Schrebler, R. [Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Av. Universidad 330, Curauma Valparaíso (Chile); Marí, B., E-mail: bmari@fis.upv.es [Departament de Física Aplicada-ETSED, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia (Spain)

    2014-08-01

    Zinc telluride (ZnTe) thin films are prepared potentiostatically from an aqueous solution bath containing ZnCl{sub 2}, TeCl{sub 4} and LiCl on Fluorine Tin Oxide coated glass substrate to investigate its suitability as a material for solar cell technology. The appropriate potential region where formation of stoichiometric ZnTe semiconductor occurs is found to be close to − 0.85 V versus Ag/AgCl. X-ray diffraction results have indicated that all electrodeposited films have cubic structure. Quantitative analysis of energy dispersive X-ray analysis results has shown that the composition ratio (Zn:Te) of films is around (1:0.99). A direct energy gap of 2.19 eV is determined by NIR–Vis–UV spectroscopy. The effect of annealing on the crystallinity and optical properties has been reported. Impedance measurements have revealed that all grown films present a p-type electrical conductivity with acceptor density N{sub A} = 2.16 × 10{sup 19} cm{sup −3}. Furthermore, the impedance results are adjusted to an equivalent circuit having two capacitors in series (Helmholtz, C{sub H} and space charge, C{sub SC}) and two resistances R{sub CT} and R{sub SC}, which are associated with charge transfer processes. - Highlights: • ZnTe thin films were electrochemically synthetized. • We discuss the electrochemical reactions involved in ZnTe thin film formation. • ZnTe films are p-type semiconductor with acceptor concentration about 2 × 10{sup 19} cm{sup −3}. • EIS data are modeled with a two capacitor–two resistance equivalent circuit. • Faster charge transfer process occurs at the interface ZnTe/electrolitic solution.

  14. Selective-Area Micropatterning of Liquid-Phase Epitaxy-Grown Iron Garnet Films

    Science.gov (United States)

    Park, Jae-Hyuk; Cho, Jae-kyeong; Nishimura, Kazuhiro; Uchida, Hironaga; Inoue, Mitsuteru

    2004-07-01

    We investigated selective-area micropatterning of iron garnet film grown by liquid-phase epitaxy (LPE). This method of producing a flat-surface structure overcomes the disadvantages of geometrical grooves, which are formed by wet or dry etching, with a limited resolution due to underetching and nonplanar structure. Moreover, patterned iron garnet films grown by selective-area LPE have better single-crystal properties than films grown by selective-area sputter epitaxy deposition. Thus, this method offers new possibilities for the fabrication of integrated magnetooptic light switch arrays, magnetic waveguides and other magnetooptic devices.

  15. Vapor Phase Sensing Using Metal Nanorod Thin Films Grown by Cryogenic Oblique Angle Deposition

    Directory of Open Access Journals (Sweden)

    Piyush Shah

    2013-01-01

    Full Text Available We demonstrate the chemical sensing capability of silver nanostructured films grown by cryogenic oblique angle deposition (OAD. For comparison, the films are grown side by side at cryogenic (~100 K and at room temperature (~300 K by e-beam evaporation. Based on the observed structural differences, it was hypothesized that the cryogenic OAD silver films should show an increased surface enhanced Raman scattering (SERS sensitivity. COMSOL simulation results are presented to validate this hypothesis. Experimental SERS results of 4-aminobenzenethiol (4-ABT Raman test probe molecules in vapor phase show good agreement with the simulation and indicate promising SERS applications for these nanostructured thin films.

  16. Vanadium and vanadium nitride thin films grown by high power impulse magnetron sputtering

    Science.gov (United States)

    Hajihoseini, H.; Gudmundsson, J. T.

    2017-12-01

    Thin vanadium and vanadium nitride films were grown on SiO2 by non-reactive and reactive high power impulse magnetron sputtering (HiPIMS), respectively. The film properties were compared to films grown by conventional dc magnetron sputtering (dcMS) at similar conditions. We explored the influence of the stationary magnetic confinement field strength on the film properties and the process parameters. The deposition rate is much lower for non-reactive sputtering by HiPIMS than for dcMS. Furthermore, for both dcMS and HiPIMS the deposition rate is lower for strong magnetic confinement. Structural characterization was carried out using x-ray diffraction and reflection methods as well as atomic force microscopy and scanning electron microscope. Both dcMS and HiPIMS grown vanadium films are polycrystalline with similar grain size regardless of magnetic field strength. For dcMS grown vanadium films the surface roughness is higher when a strong magnetic field is used. For both non-reactive growth of vanadium and reactive growth of vanadium nitride the HiPIMS process produces denser films with lower surface roughness than dcMS does. Lowering the magnetic field strength increases the deposition rate significantly for reactive HiPIMS while it increases only slightly in the reactive dcMS case. The films grown by HiPIMS with strong magnetic confinement exhibit higher density and lower roughness. We find that the operating pressure, growth temperature, discharge voltage and film thickness has influence on the properties of HiPIMS grown vanadium nitride films. The films are denser when grown at high temperature, high discharge voltage and low pressure. The density of those films is lower for thicker films and thicker films consist of larger grain size. For all the films explored, higher density coincides with lower surface roughness. Thus, the deposition method, magnetic field strength, growth temperature, discharge voltage, film thickness and growth pressure have a significant

  17. Continuous Ultra-Thin MOS2 Films Grown by Low-Temperature Physical Vapor Deposition (Postprint)

    Science.gov (United States)

    2014-07-01

    AFRL-RX-WP-JA-2014-0151 CONTINUOUS ULTRA-THIN MOS2 FILMS GROWN BY LOW-TEMPERATURE PHYSICAL VAPOR DEPOSITION (POSTPRINT) Andrey A...DATES COVERED (From – To) 01 July 2010 – 15 June 2014 4. TITLE AND SUBTITLE CONTINUOUS ULTRA-THIN MOS2 FILMS GROWN BY LOW- TEMPERATURE PHYSICAL VAPOR...devices. This Letter describes a vapor phase growth technique for precisely controlled synthesis of continuous, uniform molecular layers of MoS2 on

  18. Influence of different carrier gases on the properties of ZnO films grown by MOCVD

    Directory of Open Access Journals (Sweden)

    Wang, Jinzhong

    2008-08-01

    Full Text Available ZnO films were grown on sapphire (001 substrate by atmospheric MOCVD using diethyl zinc and tertiary butanol precursors. The influence of different carrier gases (H2 and He on the properties was analyzed by their structural (XRD, microstructural (SEM and compositional (SIMS characterization. The intensity of the strongest diffraction peak from ZnO (002 plane was increased by about 2 orders of magnitude when He is used as carrier gas, indicating the significant enhancement in crystallinity. The surface of the samples grown using H2 and He carrier gases was composed of leaf-like and spherical grains respectively. Hydrogen [H] content in the film grown using H2 is higher than that using He, indicating that the [H] was influenced by the H2 carrier gas. Ultraviolet emission dominates the low temperature PL spectra. The emission from ZnO films grown using He show higher optical quality and more emission centers.

    Se depositaron películas de ZnO sobre sustratos de zafiro (001 utilizando dietil zinc y butanol terciario como precursores. La influencia de los diferentes gases portadores (H2 y He sobre las propiedades se estudió mediante la caracterización estructural (XRD, microestructural (SEM y composicional (SIMS. La intensidad del pico de difracción más importante del plano (002 del ZnO aumentó en dos órdenes de magnitud cuando se utiliza He como gas portador indicando un incremento significativo de la cristalinidad. La superficie de las muestras crecidas utilizando H2 y He está formada por granos en forma de hoja y de forma esférica respectivamente. El contenido en hidrógeno (H en la película es mayor cuando se utiliza H2 que cuando se utiliza He, indicando que la cantidad de hidrógeno está influenciada por el H2 del gas portador. La emisión ultravioleta domina el espectro PL de baja temperatura. La emisión de las películas de ZnO utilizando

  19. Structural and optical properties of ZnO films grown on silicon and ...

    Indian Academy of Sciences (India)

    Structural and optical properties of ZnO films grown on silicon and their applications in MOS devices in conjunction with ZrO2 as a gate dielectric ... Using metal insulator semiconductor (MIS) capacitor structures, the reliability and the leakage current characteristics of ZrO2 films have been studied both at room and high ...

  20. X-ray study of chromium oxide films epitaxially grown on MgO

    NARCIS (Netherlands)

    Du, XS; Hak, S; Rogojami, OC; Hibma, T

    2004-01-01

    Chromium oxide films grown by molecular beam epitaxy on MgO (001) substrates were characterized by x-ray diffraction (XRD) and x-ray reflectivity (XRR) measurements. The absence of random oriented peaks in the theta-2theta spectra indicated that the thin films were a single phase. Reciprocal space

  1. Analysis of composition and microstructures of Ge grown on porous silicon using Raman spectroscopy and transmission electron microscopy

    Science.gov (United States)

    Aouassa, Mansour; Jadli, Imen; Hassayoun, Latifa Slimen; Maaref, Hassen; Panczer, Gerard; Favre, Luc; Ronda, Antoine; Berbezier, Isabelle

    2017-12-01

    Composition and microstructure of Ge grown on porous silicon (PSi) by Molecular Beam Epitaxy (MBE) at different temperatures are examined using High Resolution Transmission Electron Microscopy (HRTEM) and Raman spectroscopy. Ge grown at 400 °C on PSi buffer produces a planar Ge film with high crystalline quality compared to Ge grown on bulk Si. This result is attributed to the compliant nature of PSi. Increasing growth temperature >600 °C, changes the PSi morphology, increase the Ge/Si intermixing in the pores during Ge growth and lead to obtain a composite SiGe/Si substrate. Ge content in the composite SiGe substrate can controlled via growth temperature. These substrates serve as low cost virtual substrate for high efficiency III-V/Si solar cells.

  2. Electrical properties of ZnO thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Pagni, O. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Somhlahlo, N.N. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Weichsel, C. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Leitch, A.W.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)]. E-mail: andrew.leitch@nmmu.ac.za

    2006-04-01

    We report on the electrical characterization of ZnO films grown by MOCVD on glass and sapphire substrates. After correcting our temperature variable Hall measurements by applying the standard two-layer model, which takes into account an interfacial layer, scattering mechanisms in the ZnO films were studied as well as donor activation energies determined. ZnO films grown at different oxygen partial pressures indicated the importance of growth conditions on the defect structure by means of their conductivities and conductivity activation energies.

  3. Composition and structure of sputter deposited erbium hydride thin films

    Energy Technology Data Exchange (ETDEWEB)

    ADAMS,DAVID P.; ROMERO,JUAN A.; RODRIGUEZ,MARK A.; FLORO,JERROLD A.; BANKS,JAMES C.

    2000-05-10

    Erbium hydride thin films are grown onto polished, a-axis {alpha} Al{sub 2}O{sub 3} (sapphire) substrates by reactive ion beam sputtering and analyzed to determine composition, phase and microstructure. Erbium is sputtered while maintaining a H{sub 2} partial pressure of 1.4 x 10{sup {minus}4} Torr. Growth is conducted at several substrate temperatures between 30 and 500 C. Rutherford backscattering spectrometry (RBS) and elastic recoil detection analyses after deposition show that the H/Er areal density ratio is approximately 3:1 for growth temperatures of 30, 150 and 275 C, while for growth above {approximately}430 C, the ratio of hydrogen to metal is closer to 2:1. However, x-ray diffraction shows that all films have a cubic metal sublattice structure corresponding to that of ErH{sub 2}. RBS and Auger electron that sputtered erbium hydride thin films are relatively free of impurities.

  4. ZrO{sub 2}-ZnO composite thin films for humidity sensing

    Energy Technology Data Exchange (ETDEWEB)

    Velumani, M., E-mail: velumanimohan@gmail.com; Sivacoumar, R.; Alex, Z. C. [MEMS and Sensor Division, School of Electronics Engineering, VIT University, Vellore, 632014 (India); Meher, S. R.; Balakrishnan, L. [Materials Physics Division, School of Advanced Science, VIT University, Vellore, 632014 (India)

    2016-05-23

    ZrO{sub 2}-ZnO composite thin films were grown by reactive DC magnetron sputtering. X-ray diffraction studies reveal the composite nature of the films with separate ZnO and ZrO{sub 2} phase. Scanning electron microscopy studies confirm the nanocrystalline structure of the films. The films were studied for their impedometric relative humidity (RH) sensing characteristics. The complex impedance plot was fitted with a standard equivalent circuit consisting of an inter-granular resistance and a capacitance in parallel. The DC resistance was found to be decreasing with increase in RH.

  5. Proximate composition of CELSS crops grown in NASA's Biomass Production Chamber

    Science.gov (United States)

    Wheeler, R. M.; Mackowiak, C. L.; Sager, J. C.; Knott, W. M.; Berry, W. L.

    1996-01-01

    Edible biomass from four crops of wheat (Triticum aestivum L.), four crops of lettuce (Lactuca sativa L.), four crops of potato (Solanum tuberosum L.), and three crops of soybean (Glycine max (L.) Merr.) grown in NASA's CELSS Biomass Production Chamber were analyzed for proximate composition. All plants were grown using recirculating nutrient (hydroponic) film culture with pH and electrical conductivity automatically controlled. Temperature and humidity were controlled to near optimal levels for each species and atmospheric carbon dioxide partial pressures were maintained near 100 Pa during the light cycles. Soybean seed contained the highest percentage of protein and fat, potato tubers and wheat seed contained the highest levels of carbohydrate, and lettuce leaves contained the highest level of ash. Analyses showed values close to data published for field-grown plants with several exceptions: In comparison with field-grown plants, wheat seed had higher protein levels; soybean seed had higher ash and crude fiber levels; and potato tubers and lettuce leaves had higher protein and ash levels. The higher ash and protein levels may have been a result of the continuous supply of nutrients (e.g., potassium and nitrogen) to the plants by the recirculating hydroponic culture.

  6. Thin film dielectric composite materials

    Science.gov (United States)

    Jia, Quanxi; Gibbons, Brady J.; Findikoglu, Alp T.; Park, Bae Ho

    2002-01-01

    A dielectric composite material comprising at least two crystal phases of different components with TiO.sub.2 as a first component and a material selected from the group consisting of Ba.sub.1-x Sr.sub.x TiO.sub.3 where x is from 0.3 to 0.7, Pb.sub.1-x Ca.sub.x TiO.sub.3 where x is from 0.4 to 0.7, Sr.sub.1-x Pb.sub.x TiO.sub.3 where x is from 0.2 to 0.4, Ba.sub.1-x Cd.sub.x TiO.sub.3 where x is from 0.02 to 0.1, BaTi.sub.1-x Zr.sub.x O.sub.3 where x is from 0.2 to 0.3, BaTi.sub.1-x Sn.sub.x O.sub.3 where x is from 0.15 to 0.3, BaTi.sub.1-x Hf.sub.x O.sub.3 where x is from 0.24 to 0.3, Pb.sub.1-1.3x La.sub.x TiO.sub.3+0.2x where x is from 0.23 to 0.3, (BaTiO.sub.3).sub.x (PbFeo.sub.0.5 Nb.sub.0.5 O.sub.3).sub.1-x where x is from 0.75 to 0.9, (PbTiO.sub.3).sub.- (PbCo.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.1 to 0.45, (PbTiO.sub.3).sub.x (PbMg.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.2 to 0.4, and (PbTiO.sub.3).sub.x (PbFe.sub.0.5 Ta.sub.0.5 O.sub.3).sub.1-x where x is from 0 to 0.2, as the second component is described. The dielectric composite material can be formed as a thin film upon suitable substrates.

  7. Growth and Properties of molecular beam epitaxially grown ferromagnetic Fe-doped TiO2 rutile films on TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong J.; Thevuthasan, Suntharampillai; Droubay, Timothy C.; Lea, Alan S.; Wang, Chong M.; Shutthanandan, V.; Chambers, Scott A.; Sears, R.; Taylor, B.; Sinkovic, Boris

    2004-05-03

    We have grown epitaxial Fe-doped TiO₂ rutile films on rutile TiO₂(110) substrates, and have explored the resulting compositional, structural, morphological and magnetic properties. Clusters of mixed TiO₂ rutile and Fe₃O₄ form on the surface of a continuous rutile epitaxial film during growth. Room temperature ferromagnetism is observed, and is associated with the formation of secondary phase Fe₃O₄ rather than a true diluted magnetic oxide semiconductor.

  8. Effect of substrate temperature on the structure of amorphous oxygenated hydrocarbon films grown with a pulsed supersonic methane plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Fedoseeva, Yu. V., E-mail: fedoseeva@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Pozdnyakov, G.A. [Khristianovich Institute of Theoretical and Applied Mechanics, SB RAS, Novosibirsk 630090 (Russian Federation); Okotrub, A.V.; Kanygin, M.A. [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Nastaushev, Yu. V. [Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation); Vilkov, O.Y. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Bulusheva, L.G. [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

    2016-11-01

    Highlights: • A deposition of supersonic methane plasma flow on silicon substrate produces amorphous oxygenated hydrocarbon (CO{sub x}H{sub y}) film. • The thickness, composition, and wettability of the film depend on the substrate temperature. • A rise of the substrate temperature from 500 to 700 °C promotes the sp{sup 3}-hybridization carbon formation. - Abstract: Since amorphous oxygenated hydrocarbon (CO{sub x}H{sub y}) films are promising engineering materials a study of the structure and composition of the films depending on the conditions of synthesis is important for controlling of their physicochemical properties. Here, we used the methods of scanning and transmission electron microscopy, X-ray photoelectron, near-edge X-ray absorption fine structure, Fourier transform infrared and Raman spectroscopy to reveal changes in the chemical connectivity of CO{sub x}H{sub y} films grown on silicon substrates heated to 300, 500, and 700 °C using a supersonic flow of methane plasma. It was found that the CO{sub x}H{sub y} films, deposited at 300 and 500 °C, were mainly composed of the sp{sup 2}-hybridized carbon areas with various oxygen species. A rise of the substrate temperature caused an increase of the portion of tetrahedral carbon atoms as well as carboxyl and hydroxyl groups. With growth of the substrate temperature, the film thickness reduced monotonically from 400 to 180 nm, while the film adhesion improved substantially. The films, deposited at lower temperatures, showed high hydrophilicity due to porosity and presence of oxygenated groups both at the surface and in the bulk.

  9. Structure and optical band gaps of (Ba,Sr)SnO{sub 3} films grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, Timo; Raghavan, Santosh; Ahadi, Kaveh; Kim, Honggyu; Stemmer, Susanne, E-mail: stemmer@mrl.ucsb.edu [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2016-09-15

    Epitaxial growth of (Ba{sub x}Sr{sub 1−x})SnO{sub 3} films with 0 ≤ x ≤ 1 using molecular beam epitaxy is reported. It is shown that SrSnO{sub 3} films can be grown coherently strained on closely lattice and symmetry matched PrScO{sub 3} substrates. The evolution of the optical band gap as a function of composition is determined by spectroscopic ellipsometry. The direct band gap monotonously decreases with x from to 4.46 eV (x = 0) to 3.36 eV (x = 1). A large Burnstein-Moss shift is observed with La-doping of BaSnO{sub 3} films. The shift corresponds approximately to the increase in Fermi level and is consistent with the low conduction band mass.

  10. Hardness, elastic modulus, and wear resistance of hafnium oxide-based films grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Berdova, Maria; Liu, Xuwen; Franssila, Sami, E-mail: sami.franssila@aalto.fi [Department of Materials Science and Engineering, Aalto University, 02150 Espoo (Finland); Wiemer, Claudia; Lamperti, Alessio; Tallarida, Grazia; Cianci, Elena [Laboratorio MDM, IMM CNR, Via C. Olivetti 2, 20864 Agrate Brianza (MB) (Italy); Fanciulli, Marco [Laboratorio MDM, IMM CNR, Via C. Olivetti 2, 20864 Agrate Brianza (MB), Italy and Dipartimento di Scienza dei Materiali, Università degli studi di Milano Bicocca, 20126 Milano (Italy)

    2016-09-15

    The investigation of mechanical properties of atomic layer deposition HfO{sub 2} films is important for implementing these layers in microdevices. The mechanical properties of films change as a function of composition and structure, which accordingly vary with deposition temperature and post-annealing. This work describes elastic modulus, hardness, and wear resistance of as-grown and annealed HfO{sub 2}. From nanoindentation measurements, the elastic modulus and hardness remained relatively stable in the range of 163–165 GPa and 8.3–9.7 GPa as a function of deposition temperature. The annealing of HfO{sub 2} caused significant increase in hardness up to 14.4 GPa due to film crystallization and densification. The structural change also caused increase in the elastic modulus up to 197 GPa. Wear resistance did not change as a function of deposition temperature, but improved upon annealing.

  11. Cu(In, Ga)Se2 thin film solar cells grown at low temperatures

    Science.gov (United States)

    Zhang, W.; Zhu, H.; Zhang, L.; Guo, Y.; Niu, X.; Li, Z.; Chen, J.; Liu, Q.; Mai, Y.

    2017-06-01

    Cu(In, Ga)Se2 (CIGS) thin film solar cells were grown on polyimide (PI) and soda lime glass (SLG) substrates at low substrate temperatures between 400 °C and 500 °C. Different material properties of the CIGS thin films and photovoltaic performances of the solar cells were systematically investigated. It is found that the (112), (220)/(204) and (116)/(312) peaks from X-ray diffraction (XRD) patterns show double-peak patterns as the substrate temperature decreases. The CIGS thin films grown on both PI and SLG substrates shows layered structures. The bottom and surficial layers of CIGS thin films display small size polycrystalline grains while the middle layers show large size polycrystalline grains. Both types of CIGS thin film solar cells exhibit similar efficiencies while CIGS thin film solar cells grown on PI substrates show lower open circuit voltage and fill factor but higher short circuit current density, as compared to those of CIGS thin film solar cells on SLG substrates. The highest efficiency of 6.14% has been achieved for the CIGS thin film solar cells on PI with the structure of PI/Mo/CIGS/CdS/i-ZnO/ZnO:Al/Al grid here.

  12. Controlling the grain size of polycrystalline TiO2 films grown by atomic layer deposition

    Science.gov (United States)

    Kavre Piltaver, Ivna; Peter, Robert; Šarić, Iva; Salamon, Krešimir; Jelovica Badovinac, Ivana; Koshmak, Konstantin; Nannarone, Stefano; Delač Marion, Ida; Petravić, Mladen

    2017-10-01

    The crystal structure and the grain size of thin TiO2 films grown by atomic layer deposition (ALD) were characterized by scanning electron microscopy, grazing incidence X-ray diffraction, secondary ion mass spectrometry, X-ray photoelectron spectroscopy, atomic force microscopy, and near-edge X-ray absorption fine structure spectroscopy. The films of different thicknesses between 50 and 150 nm were grown at temperatures between 200 and 250 °C with a TiCl4-H2O ALD process on two different substrates, Si and NiTi. The grain size of the anatase TiO2 was dramatically increased if a thin buffer layer of Al2O3 was deposited on substrates in the same ALD sequence prior to the TiO2 deposition. The largest TiO2 plate-like grains of more than one micrometer in diameter were observed on 150 nm thick films grown at 250 °C. The present work demonstrates that the grain size of an anatase TiO2 film can be tailored and controlled on different substrates not only by the processing temperature and film thickness, but, more dramatically, by the nanometric intermediate Al2O3 layers deposited on substrates in the same ALD sequences. The large lateral grain size is explained in terms of low density of the initial nucleation grains created in TiO2 films grown on Al2O3 layers.

  13. Phase transition of bismuth telluride thin films grown by MBE

    DEFF Research Database (Denmark)

    Fülöp, Attila; Song, Yuxin; Charpentier, Sophie

    2014-01-01

    A previously unreported phase transition between Bi2Te3 and Bi4Te3 in bismuth telluride grown by molecular beam epitaxy is recorded via XRD, AFM, and SIMS observations. This transition is found to be related to the Te/Bi beam equivalent pressure (BEP) ratio. BEP ratios below 17 favor the formation...

  14. Effect of Growth Temperature and Mn Incorporation on GaN:Mn Thin Films Grown by Plasma-Assisted MOCVD

    Directory of Open Access Journals (Sweden)

    Budi Mulyanti

    2008-09-01

    Full Text Available In this paper, the growth of GaN:Mn thin films by plasma-assisted metalorganic chemical vapor deposition (PAMOCVD method is reported. The method used in this study, utilizes a microwave cavity as a cracking cell to produce nitrogen radicals, which in turn reduce the growth temperature. Trimethylgallium (TMGa, nitrogen (N2 and cyclopentadienyl manganese tricarbonyl (CpMnT were used as a source of Ga, N and Mn, respectively, while hydrogen gas was used as a carrier gas for both TMGa and CpMnT. The effect of growth temperature and Mn incorporation on structural properties and surface morphology of GaN:Mn films are presented. The growth of GaN:Mn thin films were conducted at varied growth temperature in range of 625 oC to 700 oC and the Mn/Ga molar fraction in the range of 0.2 to 0.5. Energy dispersive of X-ray (EDX and X-ray diffraction (XRD methods were used to analyze atomic composition and crystal structure of the grown films, respectively. The surface morphology was then characterized using both atomic force microscopy (AFM and scanning electron microscopy (SEM images. A systematic XRD analysis reveal that maximum Mn incorporation that still produces single phase GaN:Mn (0002 is 6.4 % and 3.2 % for the film grown at 650 oC and 700 oC, respectively. The lattice constant and full width at half maximum (FWHM of the single phase films depend on the Mn concentration. The decrease in lattice constant accompanied by the increase in FWHM is due to incorporation of substitutional Mn on the Ga sub-lattice. The maximum values of doped Mn atoms incorporated in the wurtzite structure of GaN:Mn as substitutional atoms on Ga sub-lattice are 2.0 % and 2.5 % at 650 oC and 700 oC, respectively. AFM and SEM images show that the film grown at lower growth temperature and Mn concentration has a better surface than that of film grown at higher growth temperature and Mn concentration.

  15. High-Performance Cellulose Nanofibril Composite Films

    Science.gov (United States)

    Yan Qing; Ronald Sabo; Yiqiang Wu; Zhiyong Cai

    2012-01-01

    Cellulose nanofibril/phenol formaldehyde (CNF/PF) composite films with high work of fracture were prepared by filtering a mixture of 2,2,6,6tetramethylpiperidine-1-oxyl (TEMPO) oxidized wood nanofibers and water-soluble phenol formaldehyde with resin contents ranging from 5 to 20 wt%, followed by hot pressing. The composites were characterized by tensile testing,...

  16. Systematic investigation of the properties of TiO2 films grown by reactive ion beam sputter deposition

    Science.gov (United States)

    Bundesmann, C.; Lautenschläger, T.; Spemann, D.; Finzel, A.; Thelander, E.; Mensing, M.; Frost, F.

    2017-11-01

    TiO2 films were grown by ion beam sputter deposition under systematic variation of ion beam parameters (ion species, ion energy) and geometrical parameters (ion incidence angle, polar emission angle) and characterized with respect to film thickness, growth rate, structural properties, surface topography, composition, optical properties, and mass density. The angular distributions of film thickness and growth rate show an over-cosine shape, which is tilted in forward direction. All films are amorphous and the surface roughness is below 0.22 nm. The investigation of the composition revealed stoichiometric TiO2 with implanted backscattered primary particles. The optical properties were analysed using the Tauc Lorentz (TL) model. The amplitude parameter of the TL model was found to vary systematically with the scattering angle, whereas the impact on the other TL parameters is negligible. Mass density follows the same trends as the optical properties, i.e. optical properties and mass density are correlated. Surface roughness, atomic fraction of implanted primary particles, optical properties and mass density show similar systematic variations with process parameters, especially, with the scattering geometry (i.e. scattering angle). Ion species, ion energy and ion incidence angle have no or only a small impact. The variations in the film properties are tentatively assigned to changes in the angular and energy distribution of the sputtered target particles and backscattered primary particles.

  17. X-ray absorption study of diamond films grown by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.; Ruckman, M.W.; Skotheim, T.A. (Brookhaven National Laboratory, Upton, New York 11973 (USA)); den Boer, M.; Zheng, Y. (The City University of New York, New York, New York 10021 (USA)); Badzian, A.R.; Badzian, T.; Messier, R. (The Pennsylvania State University, University Park, Pennsylvania 16802 (USA)); Srivatsa, A.R. (Moltech Corporation, Stony Brook, New York 11974 (USA))

    1991-05-01

    Carbon {ital k}-edge x-ray absorption fine structure (XAFS) is used to study the structure and bonding of chemical vapor deposition (CVD) grown diamond and diamond-like carbon films. Diamond films grown at 875 {degree}C on silicon using a 1% CH{sub 4} /H{sub 2} mixture have near-edge spectra resembling type 1(a) natural diamond. The {ital k}-edges of the diamond-like films grown by electron cyclotron resonance CVD at 200 {degree}C using 10{sup {minus}4} Torr of CH{sub 4} show a broad main peak lacking the sharp structure of graphite or diamond. Comparing the near edges of the CVD diamond film with other carbon compounds (i.e., graphite) and the CVD diamond film, the diamond-like film shows a strong {pi}* feature at 285 eV indicative of sp{sup 2} bonded carbon and a feature at 289 eV, the {sigma}*(C--H) resonance indicating C--H bonds. The relatively weak extended x-ray absorption fine structure (EXAFS) shows that the diamond-like carbon film is highly disordered on an atomic level.

  18. Ferromagnetism in ZnTe:Cr film grown on Si(1 0 0)

    Energy Technology Data Exchange (ETDEWEB)

    Soundararajan, D. [Thin Films and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Division of Applied Chemistry and Biotechnology, Hanbat National University, San 16-1, Dukmyung, Yusong, Daejon 305-719 (Korea, Republic of); Peranantham, P. [Thin Films and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Laboratoire ' EnVironnement et Mineralurgie' UMR 7569 CNRS, INPL-ENSG, B.P. 40, 54501 VandoeuVre-les-Nancy (France); Mangalaraj, D., E-mail: dmraj800@yahoo.co [Thin Films and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046 (India); Nataraj, D. [Thin Films and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Dorosinskii, L. [National Institute of Metrology (TUBITAK-UME), P.K. 54, 41470 Gebze-Kocaeli (Turkey); Santoyo-Salazar, J. [Centro de Investigacion y de Estudios Avanzados de Instituto Politecnico Nacional, Departamento de Fisica, Av. IPN 2508, San Pedro Zacatenco, C.P. 07360, A.P. 14-740, 07000 Mexico, D.F. (Mexico); Ko, J.M., E-mail: jmko@hanbat.ac.k [Division of Applied Chemistry and Biotechnology, Hanbat National University, San 16-1, Dukmyung, Yusong, Daejon 305-719 (Korea, Republic of)

    2011-01-05

    Graphical abstract: Display Omitted Research highlights: {yields} ZnTe and Cr doped ZnTe films were deposited on Si(1 0 0) by thermal evaporation method. {yields} Structural analysis showed the presence of cubic ZnCrTe with an amorphous background due to the poor crystallinity of ZnCrTe/CrTe phase. {yields} XPS analysis revealed ZnCrTe/CrTe phase with +2 valence state. Also, it was confirmed the presence of secondary phases such as Cr{sub 2}O{sub 3} and Cr, which are antiferromagnetic in nature. {yields} MFM observation showed anisotropic domains with an average size of 3.5 nm. {yields}M-H measurements showed obvious hysteresis loop even at 300 K. {yields}M-T measurements showed short-range ferromagnetic behavior and it persisted up to 354.5 K. {yields} The cubic ZnCrTe and amorphous ZnCrTe/CrTe is believed to be the reason for the observed ferromagnetic behavior. - Abstract: Zn{sub 1-x}Cr{sub x}Te (x = 0.0 and 0.05) films were grown on Si(1 0 0) substrate by using thermal evaporation method. The structure of the films was investigated by X-ray diffraction and it showed the formation of ZnCrTe phase with an amorphous background, which indicated poor crystallinity. Composition analysis by XPS disclosed the presence of antiferromagnetic Cr{sub 2}O{sub 3} and Cr precipitates. Magnetic domains were observed by using magnetic force microscopy at ambient temperature and the result showed anisotropic domains with an average size of 3.5 nm. Magnetic field dependence of magnetic moment measurements showed obvious hysteresis loop with a coercive field of 121 Oe at 300 K. Temperature dependence of magnetic moment showed short-range ferromagnetic order. The Curie temperature was estimated to be 354.5 K.

  19. Nanocrystalline magnetite thin films grown by dual ion-beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Pilar, E-mail: pilar.prieto@uam.es [Departamento de Física Aplicada M-12, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Ruiz, Patricia [Departamento de Física Aplicada M-12, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Ferrer, Isabel J. [Departamento de Física de Materiales M-4, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Figuera, Juan de la; Marco, José F. [Instituto de Química Física “Rocasolano”, CSIC, Serrano 119, 28006 Madrid (Spain)

    2015-07-05

    Highlights: • We have grown tensile and compressive strained nanocrystalline magnetite thin films by dual ion beam sputtering. • The magnetic and thermoelectric properties can be controlled by the deposition conditions. • The magnetic anisotropy depends on the crystalline grain size. • The thermoelectric properties depend on the type of strain induced in the films. • In plane uniaxial magnetic anisotropy develops in magnetite thin films with grain sizes ⩽20 nm. - Abstract: We have explored the influence of an ion-assisted beam in the thermoelectric and magnetic properties of nanocrystalline magnetite thin films grown by ion-beam sputtering. The microstructure has been investigated by XRD. Tensile and compressive strained thin films have been obtained as a function of the parameters of the ion-assisted beam. The evolution of the in-plane magnetic anisotropy was attributed to crystalline grain size. In some films, magneto-optical Kerr effect measurements reveal the existence of uniaxial magnetic anisotropy induced by the deposition process related with a small grain size (⩽20 nm). Isotropic magnetic properties have observed in nanocrystalline magnetite thin film having larger grain sizes. The largest power factor of all the films prepared (0.47 μW/K{sup 2} cm), obtained from a Seebeck coefficient of −80 μV/K and an electrical resistivity of 13 mΩ cm, is obtained in a nanocrystalline magnetite thin film with an expanded out-of-plane lattice and with a grain size ≈30 nm.

  20. Engineering the mechanical properties of ultrabarrier films grown by atomic layer deposition for the encapsulation of printed electronics

    Energy Technology Data Exchange (ETDEWEB)

    Bulusu, A.; Singh, A.; Kim, H. [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Wang, C. Y.; Dindar, A.; Fuentes-Hernandez, C.; Kippelen, B. [School of Electrical and Computer Engineering, Georgia Institute of Technology, and Center for Organic Photonics and Electronics, Atlanta, Georgia 30332 (United States); Cullen, D. [Oak Ridge National Laboratory, P.O. Box 2008 MS-6064, Oak Ridge, Tennessee 37831 (United States); Graham, S., E-mail: sgraham@gatech.edu [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Oak Ridge National Laboratory, P.O. Box 2008 MS-6064, Oak Ridge, Tennessee 37831 (United States)

    2015-08-28

    Direct deposition of barrier films by atomic layer deposition (ALD) onto printed electronics presents a promising method for packaging devices. Films made by ALD have been shown to possess desired ultrabarrier properties, but face challenges when directly grown onto surfaces with varying composition and topography. Challenges include differing nucleation and growth rates across the surface, stress concentrations from topography and coefficient of thermal expansion mismatch, elastic constant mismatch, and particle contamination that may impact the performance of the ALD barrier. In such cases, a polymer smoothing layer may be needed to coat the surface prior to ALD barrier film deposition. We present the impact of architecture on the performance of aluminum oxide (Al{sub 2}O{sub 3})/hafnium oxide (HfO{sub 2}) ALD nanolaminate barrier films deposited on fluorinated polymer layer using an optical calcium (Ca) test under damp heat. It is found that with increasing polymer thickness, the barrier films with residual tensile stress are prone to cracking resulting in rapid failure of the Ca sensor at 50 °C/85% relative humidity. Inserting a SiN{sub x} layer with residual compressive stress between the polymer and ALD layers is found to prevent cracking over a range of polymer thicknesses with more than 95% of the Ca sensor remaining after 500 h of testing. These results suggest that controlling mechanical properties and film architecture play an important role in the performance of direct deposited ALD barriers.

  1. Lightweight sodium alanate thin films grown by reactive sputtering

    NARCIS (Netherlands)

    Filippi, M.; Rector, J.H.; Gremaud, R.; Van Setten, M.J.; Dam, B.

    2009-01-01

    We report the preparation of sodium alanate, a promising hydrogen storage material, in a thin film form using cosputtering in a reactive atmosphere of atomic hydrogen. We study the phase formation and distribution, and the hydrogen desorption, with a combination of optical and infrared transmission

  2. Characterisation of molecular thin films grown by organic molecular beam deposition

    CERN Document Server

    Bayliss, S M

    2000-01-01

    This work concerns the growth and characterisation of molecular thin films in an ultra high vacuum regime by organic molecular beam deposition (OMBD). Films of three different molecular materials are grown, namely free base phthalocyanine (H sub 2 Pc), perylene 3,4,9,10-tetracarboxylic dianhydride (PTCDA) and aluminium tris-8-hydroxyquinoline (Alq sub 3). The relationship between the growth parameters such as film thickness, growth rate, and substrate temperature during and after growth, and the structural, optical and morphological properties of the film are investigated. These investigations are carried out using various ex-situ techniques. X-ray diffraction, Raman spectroscopy and electronic absorption spectroscopy are used to probe the bulk film characteristics, whilst Nomarski microscopy and atomic force microscopy are used to study the surface morphology. Three different levels of influence of the growth parameters on the film properties are observed. In the case of H sub 2 Pc, two crystal phases are fo...

  3. Characterization of PLD grown WO3 thin films for gas sensing

    Science.gov (United States)

    Boyadjiev, Stefan I.; Georgieva, Velichka; Stefan, Nicolaie; Stan, George E.; Mihailescu, Natalia; Visan, Anita; Mihailescu, Ion N.; Besleaga, Cristina; Szilágyi, Imre M.

    2017-09-01

    Tungsten trioxide (WO3) thin films were grown by pulsed laser deposition (PLD) with the aim to be applied in gas sensors. The films were studied by atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and profilometry. To study the gas sensing behavior of these WO3 films, they were deposited on quartz resonators and the quartz crystal microbalance (QCM) method was applied to analyze their gas sensitivity. Synthesis of tetragonal-WO3 films starting from a target with predominantly monoclinic WO3 phase was observed. The films deposited at 300 °C presented a surface topology favorable for the sorption properties, consisting of a film matrix with protruding craters/cavities. QCM prototype sensors with such films were tested for NO2 sensing. The PLD grown WO3 thin films show good sensitivity and fast reaction at room temperature, even in as-deposited state. With the presented technology, the manufacturing of QCM gas sensors is simple, fast and cost-effective, and it is also suitable for energy-effective portable equipment for on-line monitoring of environmental changes.

  4. Zinc Oxide Grown by CVD Process as Transparent Contact for Thin Film Solar Cell Applications

    Science.gov (United States)

    Faÿ, S.; Shah, A.

    Metalorganic chemical vapor deposition of ZnO films (MOCVD) [1] started to be comprehensively investigated in the 1980s, when thin film industries were looking for ZnO deposition processes especially useful for large-scale coatings at high growth rates. Later on, when TCO for thin film solar cells started to be developed, another advantage of growing TCO films by the CVD process has been highlighted: the surface roughness. Indeed, a large number of studies on CVD ZnO revealed that an as-grown rough surface cn be obtained with this deposition process [2-4]. A rough surface induces a light scattering effect, which can significantly improve light trapping (and therefore current photo-generation) within thin film silicon solar cells. The CVD process, indeed, directly leads to as-grown rough ZnO films without any post-etching step (the latter is often introduced to obtain a rough surface, when working with as-deposited flat sputtered ZnO). This fact could turn out to be a significant advantage when upscaling the manufacturing process for actual commercial production of thin film solar modules. The zinc and oxygen sources for CVD growth of ZnO films are given in Table 6.1.

  5. Hydroxyapatite thin films grown by pulsed laser deposition and radio-frequency magnetron sputtering: comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Nelea, V.; Morosanu, C.; Iliescu, M.; Mihailescu, I.N

    2004-04-30

    Hydroxyapatite (HA) thin films for applications in the biomedical field were grown by pulsed laser deposition (PLD) and radio-frequency magnetron sputtering (RF-MS) techniques. The depositions were performed from pure hydroxyapatite targets on Ti-5Al-2.5Fe (TiAlFe) alloys substrates. In order to prevent the HA film penetration by Ti atoms or ions diffused from the Ti-based alloy during and after deposition, the substrates were pre-coated with a thin buffer layer of TiN. In both cases, TiN was introduced by reactive PLD from TiN targets in low-pressure N{sub 2}. The PLD films were grown in vacuum onto room temperature substrates. The RF-MS films were deposited in low-pressure argon on substrates heated at 550 deg. C. The initially amorphous PLD thin films were annealed at 550 deg. C for 1 h in ambient air in order to restore the initial crystalline structure of HA target. The thickness of the PLD and RF-MS films were {approx}1 {mu}m and {approx}350 nm, respectively. All films were structurally studied by scanning electron microscopy (SEM), grazing incidence X-ray diffraction (GIXRD), energy dispersive X-ray spectrometry (EDS) and white light confocal microscopy (WLCM). The mechanical properties of the films were tested by Berkovich nano-indentation. Both PLD and RF-MS films mostly contain HA phase and exhibit good mechanical characteristics. Peaks of CaO were noticed as secondary phase in the GIXRD patterns only for RF-MS films. By its turn, the sputtered films were smoother as compared to the ones deposited by PLD (50 nm versus 250 nm average roughness). The RF-MS films were harder, more mechanically resistant and have a higher Young modulus.

  6. Relation between the microstructure and magnetic properties of BaFe12O19 thin films grown on various substrates

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.

    2002-01-01

    Barium ferrite films grown on sapphire and oxidized silicon substrates exhibit a granular structure with cluster-like magnetic domains. On sapphire, high perpendicular anisotropy can be achieved.The films grown on SiO2 /Si develop textures with nearly in-plane c axis, which induce a large in-plane

  7. Structural and optical properties of ZnO films grown on silicon and ...

    Indian Academy of Sciences (India)

    TECS

    Abstract. Photoluminescence (PL) properties of undoped ZnO thin films grown by rf magnetron sputtering on silicon substrates have been investigated. ZnO/Si substrates are characterized by Rutherford backscat- tering (RBS), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and X-ray photoelectron spectro-.

  8. Antiperovskite Sr3 PbO thin films grown by molecular beam epitaxy

    Science.gov (United States)

    Samal, Debakanta; Nakamura, Hiroyuki; Takagi, Hidenori

    Several antiperovskite compounds have recently been predicted to host bulk three dimensional Dirac dispersion as well as surface states protected by crystal symmetry. Here, we present fabrication of cubic antiperovskite Sr3PbO films epitaxially grown on LaAlO3 by molecular beam epitaxy. Fabricated films were capped with polymer without breaking vacuum to facilitate ex-situ transport characterization. All of the films showed metallic temperature dependence. The Hall effect measurement suggests that the carrier type is hole, whose density is around 5 ×1019 cm-3. Details of magnetotransport at low temperature is also described.

  9. Optimized growth conditions of epitaxial SnSe films grown by pulsed laser deposition

    Science.gov (United States)

    Hara, Takamitsu; Fujishiro, Hiroyuki; Naito, Tomoyuki; Ito, Akihiko; Goto, Takashi

    2017-12-01

    We have grown epitaxial tin monoselenide (SnSe) films on MgO or SrTiO3 (STO) substrates by pulsed laser deposition (PLD) at T s = 473 or 573 K, and investigated the optimized growth condition in terms of crystal orientation, crystallinity, and electrical resistivity. For the PLD procedure, a SnSe x (x = 1.0–1.6) target containing excess Se was used to compensate for the vaporization of Se. The crystal orientation and crystallinity of the SnSe films changed depending on the growth conditions, and the magnitude of the electrical resistivity ρ of the films was closely related to the crystalline nature. The SnSe film grown on the MgO substrate at T s = 573 K using the target with x = 1.4 was the most highly a-axis-oriented and highly crystalized among all of the films investigated in this study. However, the ρ of the film in the bc-plane was about one order of magnitude larger than those of the reported single crystal and the a-axis-oriented crystalline sample fabricated by spark plasma sintering. This larger ρ was suggested to result from the lattice mismatch and/or a small amount of nonstoichiometry in the film.

  10. Thickness-Dependent Permanent Magnet Properties of Zr2Co_{11} Thin Films Grown on Si with Pt Underlayer

    Science.gov (United States)

    Yüzüak, Gizem Durak; Yüzüak, Ercüment; Teichert, Niclas; Hütten, Andreas; Elerman, Yalçın

    2017-05-01

    Zr-Co is one of the essential magnetic materials due to its interesting magnetic and structural properties. In this work, we studied the magnetic and structural properties of Zr2Co_{11} thin films of different thicknesses grown on Si substrate with Pt underlayer. The structural properties and chemical composition of the Zr2Co_{11} films were investigated by X-ray diffraction analysis, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis, and atomic force microscopy-magnetic force microscopy measurements. The saturation magnetization, M( H) characteristic, and Henkel plots of the Zr-Co films were obtained by vibrating-sample magnetometry. The results show that H_{ {c}} and (BH)_{\\max } were enhanced with decreasing layer thickness of Zr-Co. For 10-nm Zr2Co_{11} with 20-nm Pt underlayer thin film, we observed coercive field of 2 kOe with energy product of 0.7 MGOe. Our results may be valuable for use of Zr2Co_{11} thin films in nanomagnet applications.

  11. Nanostructured Diamond-Like Carbon Films Grown by Off-Axis Pulsed Laser Deposition

    Directory of Open Access Journals (Sweden)

    Seong Shan Yap

    2015-01-01

    Full Text Available Nanostructured diamond-like carbon (DLC films instead of the ultrasmooth film were obtained by pulsed laser ablation of pyrolytic graphite. Deposition was performed at room temperature in vacuum with substrates placed at off-axis position. The configuration utilized high density plasma plume arriving at low effective angle for the formation of nanostructured DLC. Nanostructures with maximum size of 50 nm were deposited as compared to the ultrasmooth DLC films obtained in a conventional deposition. The Raman spectra of the films confirmed that the films were diamond-like/amorphous in nature. Although grown at an angle, ion energy of >35 eV was obtained at the off-axis position. This was proposed to be responsible for subplantation growth of sp3 hybridized carbon. The condensation of energetic clusters and oblique angle deposition correspondingly gave rise to the formation of nanostructured DLC in this study.

  12. Amorphous indium gallium zinc oxide thin film grown by pulse laser deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Mistry, Bhaumik V., E-mail: bhaumik-phy@yahoo.co.in; Joshi, U. S. [Department of Physics, University School of Sciences, Gujarat University, Ahmedabad-380 009 (India)

    2016-05-23

    Highly electrically conducting and transparent in visible light IGZO thin film were grown on glass substrate at substrate temperature of 400 C by a pulse laser deposition techniques. Structural, surface, electrical, and optical properties of IGZO thin films were investigated at room temperature. Smooth surface morphology and amorphous nature of the film has been confirmed from the AFM and GIXRD analysis. A resistivity down to 7.7×10{sup −3} V cm was reproducibly obtained while maintaining optical transmission exceeding 70% at wavelengths from 340 to 780 nm. The carrier densities of the film was obtain to the value 1.9×10{sup 18} cm{sup 3}, while the Hall mobility of the IGZO thin film was 16 cm{sup 2} V{sup −1}S{sup −1}.

  13. High quality atomically thin PtSe2 films grown by molecular beam epitaxy

    Science.gov (United States)

    Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

    2017-12-01

    Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

  14. Nondestructive measurement of homoepitaxially grown GaN film thickness with Fourier transform infrared spectroscopy

    Science.gov (United States)

    Horikiri, Fumimasa; Narita, Yoshinobu; Yoshida, Takehiro

    2017-12-01

    In vertical devices containing GaN homoepitaxial layers on GaN substrates, the layer thickness is a key parameter that needs to be clarified before starting the device process. We applied Fourier transform infrared spectroscopy (FT-IR) to a homoepitaxially grown GaN film that consisted of an n‑-GaN layer. The estimated film thickness from the FT-IR spectrum agreed well with the results of cross-sectional scanning electron microscope cathodoluminescence images. This is the first report of nondestructive film thickness measurements for homoepitaxially grown GaN and indicates the applicability of FT-IR to the nondestructive inspection of vertical GaN power devices.

  15. Enhancement of critical current density in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films grown using PLD on YSZ (001) surface modified with Ag nano-dots

    Energy Technology Data Exchange (ETDEWEB)

    Ionescu, M [Institute for Superconducting and Electronic Materials, University of Wollongong (Australia); Li, A H [Institute for Superconducting and Electronic Materials, University of Wollongong (Australia); Zhao, Y [Institute for Superconducting and Electronic Materials, University of Wollongong (Australia); Liu, H K [Institute for Superconducting and Electronic Materials, University of Wollongong (Australia); Crisan, A [Department of Physics, University of Bath (United Kingdom); National Institute for Materials Physics, Bucharest (Romania)

    2004-07-07

    Y123 thin films were grown by pulsed laser deposition (PLD) on YSZ (001) substrate. Prior to the film deposition, a discontinuous layer of Ag was deposited on the substrate, also using PLD, in the form of separate islands. Atomic force microscopy (AFM) investigation of the Ag layer showed that its morphology consisted of self-assembled islands of nanometre size, randomly distributed on the surface of the substrate, called nano-dots. The Y123 superconducting films grown on such a surface were characterized using AFM, x-ray diffraction, secondary electron microscopy, ac susceptibility and dc magnetization. The results show that there is no significant difference in surface morphology, crystallographic orientation, phase composition or superconducting transition temperature between the Y123 films grown on YSZ (001) with an Ag nano-dots layer and a control Y123 film grown on a virgin YSZ (001) surface. On the other hand, at 77 K, the magnetic critical current density ( J{sub c}{sup m}) was three times higher for the Y123 film grown on YSZ with the modified (001) surface than for the film grown on YSZ with a virgin (001) surface. At 5 K the enhancement of J{sub c}{sup m} was approximately seven times, at both low and high fields. This suggests an increase in pinning, caused presumably by point defects formed in the Y123 film above the Ag islands.

  16. Structural and nonlinear optical properties of as-grown and annealed metallophthalocyanine thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zawadzka, A., E-mail: azawa@fizyka.umk.pl [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Płóciennik, P.; Strzelecki, J. [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Pranaitis, M.; Dabos-Seignon, S.; Sahraoui, B. [LUNAM Université, Université d' Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 bd Lavoisier, 49045 Angers cedex (France)

    2013-10-31

    The paper presents the Third Harmonic Generation investigation of four metallophtalocyanine (MPc, M = Cu, Co, Mg and Zn) thin films. The investigated films were fabricated by Physical Vapor Deposition in high vacuum onto quartz substrates. MPc thin films were annealed after fabrication in ambient atmosphere for 12 h at the temperature equal to 150 °C or 250 °C. The Third Harmonic Generation spectra were measured to investigate the nonlinear optical properties and their dependence on the structure of the thin film after the annealing process. This approach allowed us to determine the electronic contribution of the third-order nonlinear optical susceptibility χ{sup <3>}{sub elec} of these MPc films and to investigate two theoretical models for explanation of the observed results. We find that the annealing process significantly changes the optical and structural properties of MPc thin films. - Highlights: • Metallophtalocyanine thin films were grown by Physical Vapor Deposition technique. • MPcs thin films were undergone an annealing process in ambient atmosphere. • Third Harmonic spectra were measured to investigate nonlinear optical properties. • The third order nonlinear optical susceptibility χ{sup <3>}{sub elec} was determined. • We report changing both nonlinear optical and structural properties of thin films.

  17. Crystal orientation, crystallinity, and thermoelectric properties of Bi0.9Sr0.1CuSeO epitaxial films grown by pulsed laser deposition

    Science.gov (United States)

    Ishizawa, Mamoru; Fujishiro, Hiroyuki; Naito, Tomoyuki; Ito, Akihiko; Goto, Takashi

    2018-02-01

    We have grown Bi0.9Sr0.1CuSeO epitaxial thin films on MgO and SrTiO3 (STO) single-crystal substrates by pulsed laser deposition (PLD) under various growth conditions, and investigated the crystal orientation, crystallinity, chemical composition, and thermoelectric properties of the films. The optimization of the growth conditions was realized in the film grown on MgO at the temperature T s = 573 K and Ar pressure P Ar = 0.01 Torr in this study, in which there was no misalignment apart from the c-axis and no impurity phase. It was clearly found that the higher crystal orientation of the epitaxial film grown at a higher temperature under a lower Ar pressure mainly enhanced the thermoelectric power factor P (= S 2/ρ), where S is the Seebeck coefficient and ρ is the electrical resistivity. However, the thermoelectric properties of the films were lower than those of polycrystalline bulk because of lattice distortion from lattice mismatch, a low crystallinity caused by a lower T s, and Bi and Cu deficiencies in the films.

  18. Amorphous Silicon Nanowires Grown on Silicon Oxide Film by Annealing

    Science.gov (United States)

    Yuan, Zhishan; Wang, Chengyong; Chen, Ke; Ni, Zhonghua; Chen, Yunfei

    2017-08-01

    In this paper, amorphous silicon nanowires (α-SiNWs) were synthesized on (100) Si substrate with silicon oxide film by Cu catalyst-driven solid-liquid-solid mechanism (SLS) during annealing process (1080 °C for 30 min under Ar/H2 atmosphere). Micro size Cu pattern fabrication decided whether α-SiNWs can grow or not. Meanwhile, those micro size Cu patterns also controlled the position and density of wires. During the annealing process, Cu pattern reacted with SiO2 to form Cu silicide. More important, a diffusion channel was opened for Si atoms to synthesis α-SiNWs. What is more, the size of α-SiNWs was simply controlled by the annealing time. The length of wire was increased with annealing time. However, the diameter showed the opposite tendency. The room temperature resistivity of the nanowire was about 2.1 × 103 Ω·cm (84 nm diameter and 21 μm length). This simple fabrication method makes application of α-SiNWs become possible.

  19. Electrochromism and photocatalysis in dendrite structured Ti:WO3 thin films grown by sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Karuppasamy, A., E-mail: karuppasamy@psnacet.edu.in

    2015-12-30

    Graphical abstract: - Highlights: • Dendrite structured Ti doped WO{sub 3} (WTO) thin films are grown by co-sputtering. • Sputtering condition influences structure and surface morphology of WTO films. • Titanium doping and annealing lead to dendritic surface structures in WTO films. • Structural, optical, electrochromic and photocatalytic properties of WTO films. • Enhanced electrochromism and photocatalysis in dendrite structured WTO thin films. - Abstract: Titanium doped tungsten oxide (Ti:WO{sub 3}) thin films with dendrite surface structures were grown by co-sputtering titanium and tungsten in Ar + O{sub 2} atmosphere. Ti:WO{sub 3} thin films were deposited at oxygen flow rates corresponding to pressures in the range 1.0 × 10{sup −3}–5.0 × 10{sup −3} mbar. Argon flow rate and sputtering power densities for titanium (2 W/cm{sup 2}) and tungsten (3 W/cm{sup 2}) were kept constant. Ti:WO{sub 3} films deposited at an oxygen pressure of 5 × 10{sup −3} mbar are found to be better electrochromic and photocatalytic. They have high optical modulation (80% at λ = 550 nm), coloration efficiency (60 cm{sup 2}/C at λ = 550 nm), electron/ion storage and removal capacity (Qc: −22.01 mC/cm{sup 2}, Qa: 17.72 mC/cm{sup 2}), reversibility (80%) and methylene blue decomposition rate (−1.38 μmol/l d). The combined effects of titanium doping, dendrite surface structures and porosity leads to significant enhancement in the electrochromic and photocatalytic properties of Ti:WO{sub 3} films.

  20. High-quality AlN films grown on chemical vapor-deposited graphene films

    Directory of Open Access Journals (Sweden)

    Chen Bin-Hao

    2016-01-01

    Full Text Available We report the growth of high-quality AlN films on graphene. The graphene films were synthesized by CVD and then transferred onto silicon substrates. Epitaxial aluminum nitride films were deposited by DC magnetron sputtering on both graphene as an intermediate layer and silicon as a substrate. The structural characteristics of the AlN films and graphene were investigated. Highly c-axis-oriented AlN crystal structures are investigated based on the XRDpatterns observations.

  1. AlN thin film grown on different substrates by hydride vapor phase epitaxy

    Science.gov (United States)

    Sun, M. S.; Zhang, J. C.; Huang, J.; Wang, J. F.; Xu, K.

    2016-02-01

    AlN thin films have been grown on GaN/sapphire templates, 6 H-SiC and sapphire by hydride vapor phase epitaxy. The influence of growth conditions and substrates on the crystal qualities and growth mode has been investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The results showed that the low pressure was favorable for high-quality AlN thin film growth around 1000 °C. The full-width at half-maximum (FWHM) of (0002) XRD of 200-nm AlN thin film grown on GaN/sapphire, 6 H-SiC and sapphire are 220, 187 and 260 arc s, respectively. While the corresponding counterparts of (10-12) are 1300, 662 and 2650 arc s, respectively. Both suggested that low dislocation density in AlN grown on 6 H-SiC. The morphology of AlN thin film on sapphire showed islands without coalescence initially, and then changed to be coalescent with atomic steps at 1200 nm. However, those for samples on 6 H-SiC and GaN/sapphire showed smooth surface with clear atomic steps at thickness of 200 nm. The result indicated different growth modes of AlN on different substrates. It was believed that the different lattice mismatchs between AlN and substrates led to the different crystal qualities and growth modes.

  2. N-Type Conductive Ultrananocrystalline Diamond Films Grown by Hot Filament CVD

    Directory of Open Access Journals (Sweden)

    Michael Mertens

    2015-01-01

    Full Text Available We present the synthesis of ultrananocrystalline diamond (UNCD films by application of hot filament chemical vapor deposition (HFCVD. We furthermore studied the different morphological, structural, and electrical properties. The grown films are fine grained with grain sizes between 4 and 7 nm. The UNCD films exhibit different electrical conductivities, dependent on grain boundary structure. We present different contact metallizations exhibiting ohmic contact behavior and good adhesion to the UNCD surface. The temperature dependence of the electrical conductivity is presented between −200 and 900°C. We furthermore present spectroscopic investigations of the films, supporting that the origin of the conductivity is the structure and volume of the grain boundary.

  3. Highly crystalline MoS{sub 2} thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Serrao, Claudy R.; You, Long; Gadgil, Sushant; Hu, Chenming; Salahuddin, Sayeef [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Diamond, Anthony M.; Hsu, Shang-Lin; Clarkson, James [Department of Material Science and Engineering, University of California, Berkeley, California 94720 (United States); Carraro, Carlo; Maboudian, Roya [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States)

    2015-02-02

    Highly crystalline thin films of MoS{sub 2} were prepared over large area by pulsed laser deposition down to a single monolayer on Al{sub 2}O{sub 3} (0001), GaN (0001), and SiC-6H (0001) substrates. X-ray diffraction and selected area electron diffraction studies show that the films are quasi-epitaxial with good out-of-plane texture. In addition, the thin films were observed to be highly crystalline with rocking curve full width half maxima of 0.01°, smooth with a RMS roughness of 0.27 nm, and uniform in thickness based on Raman spectroscopy. From transport measurements, the as-grown films were found to be p-type.

  4. Reordering between tetrahedral and octahedral sites in ultrathin magnetite films grown on MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Bertram, F.; Deiter, C. [Hamburger Synchrotronstrahlungslabor am Deutschen Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg (Germany); Schemme, T.; Jentsch, S.; Wollschlaeger, J. [Fachbereich Physik, Universitaet Osnabrueck, Barbarastr. 7, 49069 Osnabrueck (Germany)

    2013-05-14

    Magnetite ultrathin films were grown using different deposition rates and substrate temperatures. The structure of these films was studied using (grazing incidence) x-ray diffraction, while their surface structure was characterized by low energy electron diffraction. In addition to that, we performed x-ray photoelectron spectroscopy and magneto optic Kerr effect measurements to probe the stoichiometry of the films as well as their magnetic properties. The diffraction peaks of the inverse spinel structure, which originate exclusively from Fe ions on tetrahedral sites are strongly affected by the preparation conditions, while the octahedral sites remain almost unchanged. With both decreasing deposition rate as well as decreasing substrate temperature, the integrated intensity of the diffraction peaks originating exclusively from Fe on tetrahedral sites is decreasing. We propose that the ions usually occupying tetrahedral sites in magnetite are relocated to octahedral vacancies. Ferrimagnetic behaviour is only observed for well ordered magnetite films.

  5. Doped zinc oxide films grown by hot-wire chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abrutis, A., E-mail: adulfas.abrutis@chf.vu.lt; Silimavicius, L.; Kubilius, V.; Murauskas, T.; Saltyte, Z.; Plausinaitiene, V.

    2015-02-02

    Hot-wire chemical vapour deposition (CVD) was applied to grow zinc oxide (ZnO)-based transparent conducting oxide films. Indium (In)-, gallium (Ga)-, and aluminium (Al)-doped ZnO films were deposited at 400 °C on sapphire-R, Si (100) and glass substrates using a cold wall pulsed liquid injection CVD system containing nichrome wires installed in front of the substrate holder. Zn, In, Al 2,2,6,6-tetramethyl-3,5-heptanedionates, and Ga 3,5-pentanedionate dissolved in 1,2-dimethoxyethane were used as precursors. Hall measurements were performed to evaluate the resistivity, carrier concentration, and carrier mobility in doped ZnO films grown on sapphire substrates at wire currents of 6 A and 9 A. The influence of the dopant type, doping level, substrate, and wire heating current on crystallinity and the electrical and optical properties of the films was investigated and discussed. The best electrical properties were obtained for Al- and Ga-doped films grown at 9 A wire current (resistivity ≈ 1 × 10{sup −3} Ωcm, carrier mobility ≈ 50 cm{sup 2} V{sup −1} s{sup −1} and carrier concentration ≈ 1 × 10{sup 20} cm{sup −3}). The films exhibited a high transmittance in the mid-infrared region (≈ 90% at 2.5 μm). Additional annealing of the films at 400 °C in a mixture of Ar and hydrogen (10%) resulted in the increase in carrier concentration and mobility and in the reduction of film resistivity. - Highlights: • Hot-wire CVD process was applied for the growth of In-, Ga-, and Al-doped ZnO films. • Electrical and optical properties of as-deposited and annealed films were investigated. • Significant influence of film orientation on electrical properties was observed. • Films exhibited high carrier mobility (50–60 cm{sup 2} V{sup −1} s{sup −1}) and low resistivity (≤ 10{sup −3} Ωcm). • Films had high transmittance (~ 90%) in the mid-IR spectral range (at 2.5 μm)

  6. Adsorption properties of Mg-Al layered double hydroxides thin films grown by laser based techniques

    Energy Technology Data Exchange (ETDEWEB)

    Matei, A., E-mail: andreeapurice@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest, Magurele (Romania); Birjega, R.; Vlad, A.; Filipescu, M.; Nedelcea, A.; Luculescu, C. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest, Magurele (Romania); Zavoianu, R.; Pavel, O.D. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest (Romania); Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest, Magurele (Romania)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Laser techniques MAPLE and PLD can successfully be used to produce LDHs thin films. Black-Right-Pointing-Pointer Hydration treatments of the PLD and MAPLE deposited films lead to the LDH reconstruction effect. Black-Right-Pointing-Pointer The Ni retention from aqueous solution occurs in the films via a dissolution-reconstruction mechanism. Black-Right-Pointing-Pointer The films are suitable for applications in remediation of contaminated drinking water or waste waters. - Abstract: Powdered layered double hydroxides (LDHs) have been widely studied due to their applications as catalysts, anionic exchangers or host materials for inorganic and/or organic molecules. Assembling nano-sized LDHs onto flat solid substrates forming thin films is an expanding area of research due to the prospects of novel applications as sensors, corrosion-resistant coatings, components in optical and magnetic devices. Continuous and adherent thin films were grown by laser techniques (pulsed laser deposition - PLD and matrix assisted pulsed laser evaporation - MAPLE) starting from targets of Mg-Al LDHs. The capacity of the grown thin films to retain a metal (Ni) from contaminated water has been also explored. The thin films were immersed in an Ni(NO{sub 3}){sub 2} aqueous solutions with Ni concentrations of 10{sup -3}% (w/w) (1 g/L) and 10{sup -4}% (w/w) (0.1 g/L), respectively. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX) were the techniques used to characterize the prepared materials.

  7. Yttria and ceria doped zirconia thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Saporiti, F.; Juarez, R. E., E-mail: cididi@fi.uba.ar [Grupo de Materiales Avanzados, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Audebert, F. [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Boudard, M. [Laboratoire des Materiaux et du Genie Physique (CNRS), Grenoble (France)

    2013-11-01

    The Yttria stabilized Zirconia (YSZ) is a standard electrolyte for solid oxide fuel cells (SOFCs), which are potential candidates for next generation portable and mobile power sources. YSZ electrolyte thin films having a cubic single phase allow reducing the SOFC operating temperature without diminishing the electrochemical power density. Films of 8 mol% Yttria stabilized Zirconia (8YSZ) and films with addition of 4 weight% Ceria (8YSZ + 4CeO{sub 2}) were grown by pulsed laser deposition (PLD) technique using 8YSZ and 8YSZ + 4CeO{sub 2} targets and a Nd-YAG laser (355 nm). Films have been deposited on Soda-Calcia-Silica glass and Si(100) substrates at room temperature. The morphology and structural characteristics of the samples have been studied by means of X-ray diffraction and scanning electron microscopy. Films of a cubic-YSZ single phase with thickness in the range of 1-3 Micro-Sign m were grown on different substrates (author)

  8. Group III-nitride thin films grown using MBE and bismuth

    Science.gov (United States)

    Kisielowski, Christian K.; Rubin, Michael

    2000-01-01

    The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

  9. Irradiation induced improvement in crystallinity of epitaxially grown Ag thin films on Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Takahiro, Katsumi; Nagata, Shinji; Yamaguchi, Sadae [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    1997-03-01

    We report the improvement in crystallinity of epitaxially grown Ag films on Si(100) substrates with ion irradiation. The irradiation of 0.5 MeV Si ions to 2x10{sup 16}/cm{sup 2} at 200degC, for example, reduces the channeling minimum yield from 60% to 6% at Ag surface. The improvement originates from the decrease of mosaic spread in the Ag thin film. In our experiments, ion energy, ion species and irradiation temperature have been varied. The better crystallinity is obtained as the higher concentration of defect is generated. The mechanism involved in the irradiation induced improvement is discussed. (author)

  10. Raman shift on n-doped amorphous carbon thin films grown by electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Rebollo P., B. [Departamento de Fisica, Pontificia Universidad Catolica de Rio de Janeiro (Brazil); Facultad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla (Mexico); Freire L., F. Jr. [Departamento de Fisica, Pontificia Universidad Catolica de Rio de Janeiro (Brazil); Lozada M., R.; Palomino M., R. [Facultad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla (Mexico); Jimenez S., S. [Centro de Investigacion y de Estudios Avanzados del IPN, Laboratorio de Investigacion en Materiales, Queretaro (Mexico); Zelaya A., O. [Centro de Investigacion y de Estudios Avanzados del IPN, Departamento de Fisica, CINVESTAV-IPN, P.O. Box 14-740, Mexico 07360 D.F. (Mexico)

    2007-04-15

    The structural properties of carbon thin films synthesized under an atmosphere of nitrogen by means of electron beam evaporation were studied by Raman scattering spectroscopy. The electron beam evaporation technique is an important alternative to grown layers of this material with interesting structural properties. The observed shift of the Raman G band shows that the structure of the films tends to become more graphitic upon the increase of the deposition time. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Eu-Doped GaN Films Grown by Phase Shift Epitaxy

    Science.gov (United States)

    Zhong, Mingyu; Steckl, Andrew J.

    2010-12-01

    Phase shift epitaxy (PSE) is a dynamic thin film growth technique wherein constituent fluxes are pulsed with an adjustable phase shift. PSE enables the introduction of dopants during the optimum segment of the growth cycle. Eu-doped GaN films were grown with Ga and Eu shutters periodically opened and closed (with varying phase shift) while keeping N flux constant, so that the Ga and Eu coverage on surface during each cycle varies in a controlled way. The Eu concentration and photoluminescence (PL) efficiency are strongly influenced by the PSE parameters. Eu ions doped during high Ga coverage exhibit strong PL efficiency.

  12. Effect of thermal annealing on ZnO:Al thin films grown by spray pyrolysis

    Science.gov (United States)

    El Manouni, A.; Manjón, F. J.; Perales, M.; Mollar, M.; Marí, B.; Lopez, M. C.; Ramos Barrado, J. R.

    2007-07-01

    We report the effect of thermal annealing in air on the structural and optical properties of undoped and aluminium-doped (1%-4%) zinc oxide (AZO) thin films, grown by the spray pyrolysis technique on quartz substrates. Films were characterized by X-ray diffraction, low-temperature photoluminescence, electrical resistivity, and Raman spectroscopy after annealing at temperatures between 500 and 900 ∘C. Annealing in air improves the long-range order crystalline quality of the bulk crystals, but promotes a number of point defects in the surface affecting both the resistivity and the photoluminescence.

  13. Solution-Grown Monocrystalline Hybrid Perovskite Films for Hole-Transporter-Free Solar Cells

    KAUST Repository

    Peng, Wei

    2016-03-02

    High-quality perovskite monocrystalline films are successfully grown through cavitation-triggered asymmetric crystallization. These films enable a simple cell structure, ITO/CH3NH3PbBr3/Au, with near 100% internal quantum efficiency, promising power conversion efficiencies (PCEs) >5%, and superior stability for prototype cells. Furthermore, the monocrystalline devices using a hole-transporter-free structure yield PCEs ≈6.5%, the highest among other similar-structured CH3NH3PbBr3 solar cells to date.

  14. Extremely smooth YBa 2Cu 3O 7- δ "thin" film grown by liquid phase epitaxy

    Science.gov (United States)

    Hao, Z.; Wu, Y.; Enomoto, Y.; Tanabe, K.; Koshizuka, N.

    2002-02-01

    Extremely smooth single crystal YBa 2Cu 3O 7- δ "thin" films, 1-3 μm thick, have been successfully grown on YBCO-seeded MgO substrates by liquid phase epitaxy. The morphology study on the as-grown samples has revealed a step-flow growth mechanism, with each step height of about 1.1 nm, i.e. the c-axis lattice constant of YBCO. The mean surface roughness in a large 25 μm×25 μm area is ˜0.76 nm, determined by an atomic force microscope. After annealing in pure oxygen, the ˜2 μm thick films exhibit high-quality high- Tc superconductivity with zero resistance transition temperature TC0≈91 K and critical current density JC=4.74×10 4 A/cm 2 (transport measurement with 1 μV/cm criterion) at 77 K.

  15. Room-temperature-grown rare-earth-doped GaN luminescent thin films

    Science.gov (United States)

    Lee, D. S.; Steckl, A. J.

    2001-09-01

    Visible emission has been observed from rare-earth (RE)-doped GaN electroluminescent devices (ELDs) as-grown near room temperature on Si (50-100 °C): red from GaN:Eu, green from GaN:Er, and blue from GaN:Tm. Green emission at 537/558 nm from GaN:Er ELD had a measured brightness of ˜230 cd/m2 at 46 V bias. X-ray diffraction indicates that the low-temperature-grown GaN:Er structure was oriented with the c axis perpendicular to the substrate. Scanning electron and atomic force microscopy indicate that the films had a rough surface and a compact structure consisting of small grains. Electroluminescence intensity of GaN:RE was significantly improved with postgrowth annealing. For GaN:Er films, after 800 °C annealing, the green emission brightness efficiency increased by ˜10×.

  16. Phase transitions of rare earth oxide films grown on Si(111)

    Energy Technology Data Exchange (ETDEWEB)

    Wilkens, Henrik

    2014-01-15

    In this work the structural transitions of the rare earth oxides praseodymia and ceria grown on Si(111) are investigated. It is demonstrated that several of the rare earth intermediate phases can be stabilized by post deposition annealing in ultra high vacuum. However, in most cases no single phased but coexisting species are observed. In addition, the surface structure and morphology of hex-Pr{sub 2}O{sub 3}(0001) as well as reduced ceria films are investigated.

  17. Magnetic properties of Ni films deposited on MBE grown Bi2Se3 layers

    Directory of Open Access Journals (Sweden)

    Taehee Yoo

    2017-05-01

    Full Text Available We have investigated the magnetic properties of the Ni films deposited on a GaAs and a Bi2Se3 buffer grown by molecular beam epitaxy on a GaAs (001 substrate. The magnetization measurements at 4 K revealed that the coercivity of the Ni films decreases monotonically with increasing thickness up to 25 nm in both cases. However, the coercivity measured at 4 K was always larger in the Ni film deposited on the surface of Bi2Se3 than in the film deposited on the GaAs. Such enhancement of the coercivity decreases with increasing temperature and film thickness. This suggests that the Bi2Se3 surface alters the magnetic properties of the Ni film. The increase of the coercivity was more serious in an un-capped Ni/Bi2Se3 sample, which showed an exchange bias effect due to the oxidation of the top surface of the Ni film. These observations are important for the investigation of spin dependent phenomena in magnetic systems involving a ferromagnet/topological insulator interface.

  18. Biocompatibility of GaSb thin films grown by RF magnetron sputtering

    Science.gov (United States)

    Nishimoto, Naoki; Fujihara, Junko; Yoshino, Katsumi

    2017-07-01

    GaSb may be suitable for biological applications, such as cellular sensors and bio-medical instrumentation because of its low toxicity compared with As (III) compounds and its band gap energy. Therefore, the biocompatibility and the film properties under physiological conditions were investigated for GaSb thin films with or without a surface coating. GaSb thin films were grown on quartz substrates by RF magnetron sputtering, and then coated with (3-mercaptopropyl) trimethoxysilane (MPT). The electrical properties, surface morphology, and crystal structure of the GaSb thin film were unaffected by the MPT coating. The cell viability assay suggested that MPT-coated GaSb thin films are biocompatible. Bare GaSb was particularly unstable in pH9 buffer. Ga elution was prevented by the MPT coating, although the Ga concentration in the pH 9 buffer was higher than that in the other solutions. The surface morphology and crystal structure were not changed by exposure to the solutions, except for the pH 9 buffer, and the thin film properties of MPT-coated GaSb exposed to distilled water and H2O2 in saline were maintained. These results indicate that MPT-coated GaSb thin films are biocompatible and could be used for temporary biomedical devices.

  19. Chemical resistance of thin film materials based on metal oxides grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sammelselg, Väino, E-mail: vaino.sammelselg@ut.ee [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu (Estonia); Netšipailo, Ivan; Aidla, Aleks; Tarre, Aivar; Aarik, Lauri; Asari, Jelena; Ritslaid, Peeter; Aarik, Jaan [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia)

    2013-09-02

    Etching rate of technologically important metal oxide thin films in hot sulphuric acid was investigated. The films of Al-, Ti-, Cr-, and Ta-oxides studied were grown by atomic layer deposition (ALD) method on silicon substrates from different precursors in large ranges of growth temperatures (80–900 °C) in order to reveal process parameters that allow deposition of coatings with higher chemical resistance. The results obtained demonstrate that application of processes that yield films with lower concentration of residual impurities as well as crystallization of films in thermal ALD processes leads to significant decrease of etching rate. Crystalline films of materials studied showed etching rates down to values of < 5 pm/s. - Highlights: • Etching of atomic layer deposited thin metal oxide films in hot H{sub 2}SO{sub 4} was studied. • Smallest etching rates of < 5 pm/s for TiO{sub 2}, Al{sub 2}O{sub 3}, and Cr{sub 2}O{sub 3} were reached. • Highest etching rate of 2.8 nm/s for Al{sub 2}O{sub 3} was occurred. • Remarkable differences in etching of non- and crystalline films were observed.

  20. Elastic properties of B-C-N films grown by N{sub 2}-reactive sputtering from boron carbide targets

    Energy Technology Data Exchange (ETDEWEB)

    Salas, E.; Jiménez Riobóo, R. J.; Jiménez-Villacorta, F.; Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain); Sánchez-Marcos, J. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain); Dept. Química-Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Muñoz-Martín, A.; Prieto, J. E.; Joco, V. [Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2013-12-07

    Boron-carbon-nitrogen films were grown by RF reactive sputtering from a B{sub 4}C target and N{sub 2} as reactive gas. The films present phase segregation and are mechanically softer than boron carbide films (a factor of more than 2 in Young's modulus). This fact can turn out as an advantage in order to select buffer layers to better anchor boron carbide films on substrates eliminating thermally induced mechanical tensions.

  1. Compositional analysis of silicon oxide/silicon nitride thin films

    Directory of Open Access Journals (Sweden)

    Meziani Samir

    2016-06-01

    Full Text Available Hydrogen, amorphous silicon nitride (SiNx:H abbreviated SiNx films were grown on multicrystalline silicon (mc-Si substrate by plasma enhanced chemical vapour deposition (PECVD in parallel configuration using NH3/SiH4 gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation in dry oxygen ambient environment at 950 °C to get oxide/nitride (ON structure. Secondary ion mass spectroscopy (SIMS, Rutherford backscattering spectroscopy (RBS, Auger electron spectroscopy (AES and energy dispersive X-ray analysis (EDX were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiNx. Indeed, oxygen diffused to the nitride layer into Si2O2N during dry oxidation.

  2. Adsorption properties of Mg-Al layered double hydroxides thin films grown by laser based techniques

    Science.gov (United States)

    Matei, A.; Birjega, R.; Vlad, A.; Filipescu, M.; Nedelcea, A.; Luculescu, C.; Zavoianu, R.; Pavel, O. D.; Dinescu, M.

    2012-09-01

    Powdered layered double hydroxides (LDHs) have been widely studied due to their applications as catalysts, anionic exchangers or host materials for inorganic and/or organic molecules. Assembling nano-sized LDHs onto flat solid substrates forming thin films is an expanding area of research due to the prospects of novel applications as sensors, corrosion-resistant coatings, components in optical and magnetic devices. Continuous and adherent thin films were grown by laser techniques (pulsed laser deposition - PLD and matrix assisted pulsed laser evaporation - MAPLE) starting from targets of Mg-Al LDHs. The capacity of the grown thin films to retain a metal (Ni) from contaminated water has been also explored. The thin films were immersed in an Ni(NO3)2 aqueous solutions with Ni concentrations of 10-3% (w/w) (1 g/L) and 10-4% (w/w) (0.1 g/L), respectively. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX) were the techniques used to characterize the prepared materials.

  3. Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends

    Science.gov (United States)

    Miikkulainen, Ville; Leskelä, Markku; Ritala, Mikko; Puurunen, Riikka L.

    2013-01-01

    Atomic layer deposition (ALD) is gaining attention as a thin film deposition method, uniquely suitable for depositing uniform and conformal films on complex three-dimensional topographies. The deposition of a film of a given material by ALD relies on the successive, separated, and self-terminating gas-solid reactions of typically two gaseous reactants. Hundreds of ALD chemistries have been found for depositing a variety of materials during the past decades, mostly for inorganic materials but lately also for organic and inorganic-organic hybrid compounds. One factor that often dictates the properties of ALD films in actual applications is the crystallinity of the grown film: Is the material amorphous or, if it is crystalline, which phase(s) is (are) present. In this thematic review, we first describe the basics of ALD, summarize the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD [R. L. Puurunen, J. Appl. Phys. 97, 121301 (2005)], and give an overview of the status of processing ternary compounds by ALD. We then proceed to analyze the published experimental data for information on the crystallinity and phase of inorganic materials deposited by ALD from different reactants at different temperatures. The data are collected for films in their as-deposited state and tabulated for easy reference. Case studies are presented to illustrate the effect of different process parameters on crystallinity for representative materials: aluminium oxide, zirconium oxide, zinc oxide, titanium nitride, zinc zulfide, and ruthenium. Finally, we discuss the general trends in the development of film crystallinity as function of ALD process parameters. The authors hope that this review will help newcomers to ALD to familiarize themselves with the complex world of crystalline ALD films and, at the same time, serve for the expert as a handbook-type reference source on ALD processes and film crystallinity.

  4. C-Axis-Oriented Hydroxyapatite Film Grown Using ZnO Buffer Layer

    Science.gov (United States)

    Sakoishi, Yasuhiro; Iguchi, Ryo; Nishikawa, Hiroaki; Hontsu, Shigeki; Hayami, Takashi; Kusunoki, Masanobu

    2013-11-01

    A method of fabricating c-axis-oriented hydroxyapatite film on a quartz crystal microbalance (QCM) sensor was investigated. ZnO was used as a template to obtain a hexagonal hydroxyapatite crystal of uniaxial orientation. The ZnO was grown as a c-axis film on a Au/quartz with the surface structure of a QCM sensor. Under optimized conditions, hydroxyapatite was deposited by pulsed laser deposition. X-ray diffraction showed the hydroxyapatite film to be oriented along the c-axis. Because Au and ZnO are applied to many devices, the anisotropic properties of hydroxyapatite may be incorporated into these devices as well as QCM sensors.

  5. Raman spectroscopy of ZnMnO thin films grown by pulsed laser deposition

    Science.gov (United States)

    Orozco, S.; Riascos, H.; Duque, S.

    2016-02-01

    ZnMnO thin films were grown by Pulsed Laser Deposition (PLD) technique onto Silicon (100) substrates at different growth conditions. Thin films were deposited varying Mn concentration, substrate temperature and oxygen pressure. ZnMnO samples were analysed by using Raman Spectroscopy that shows a red shift for all vibration modes. Raman spectra revealed that nanostructure of thin films was the same of ZnO bulk, wurzite hexagonal structure. The structural disorder was manifested in the line width and shape variations of E2(high) and E2(low) modes located in 99 and 434cm-1 respectively, which may be due to the incorporation of Mn ions inside the ZnO crystal lattice. Around 570cm-1 was found a peak associated to E1(LO) vibration mode of ZnO. 272cm-1 suggest intrinsic host lattice defects. Additional mode centred at about 520cm-1 can be overlap of Si and Mn modes.

  6. Molecular-Beam Epitaxially Grown MgB2 Thin Films and Superconducting Tunnel Junctions

    Directory of Open Access Journals (Sweden)

    Jean-Baptiste Laloë

    2011-01-01

    Full Text Available Since the discovery of its superconducting properties in 2001, magnesium diboride has generated terrific scientific and engineering research interest around the world. With a of 39 K and two superconducting gaps, MgB2 has great promise from the fundamental point of view, as well as immediate applications. Several techniques for thin film deposition and heterojunction formation have been established, each with its own advantages and drawbacks. Here, we will present a brief overview of research based on MgB2 thin films grown by molecular beam epitaxy coevaporation of Mg and B. The films are smooth and highly crystalline, and the technique allows for virtually any heterostructure to be formed, including all-MgB2 tunnel junctions. Such devices have been characterized, with both quasiparticle and Josephson tunneling reported. MgB2 remains a material of great potential for a multitude of further characterization and exploration research projects and applications.

  7. Large-Area WS2 Film with Big Single Domains Grown by Chemical Vapor Deposition

    Science.gov (United States)

    Liu, Pengyu; Luo, Tao; Xing, Jie; Xu, Hong; Hao, Huiying; Liu, Hao; Dong, Jingjing

    2017-10-01

    High-quality WS2 film with the single domain size up to 400 μm was grown on Si/SiO2 wafer by atmospheric pressure chemical vapor deposition. The effects of some important fabrication parameters on the controlled growth of WS2 film have been investigated in detail, including the choice of precursors, tube pressure, growing temperature, holding time, the amount of sulfur powder, and gas flow rate. By optimizing the growth conditions at one atmospheric pressure, we obtained tungsten disulfide single domains with an average size over 100 μm. Raman spectra, atomic force microscopy, and transmission electron microscopy provided direct evidence that the WS2 film had an atomic layer thickness and a single-domain hexagonal structure with a high crystal quality. And the photoluminescence spectra indicated that the tungsten disulfide films showed an evident layer-number-dependent fluorescence efficiency, depending on their energy band structure. Our study provides an important experimental basis for large-area, controllable preparation of atom-thick tungsten disulfide thin film and can also expedite the development of scalable high-performance optoelectronic devices based on WS2 film.

  8. Characterizations of InN Thin Films Grown on Si (110 Substrate by Reactive Sputtering

    Directory of Open Access Journals (Sweden)

    M. Amirhoseiny

    2011-01-01

    Full Text Available Indium nitride (InN thin films were deposited onto Si (110 by reactive sputtering and pure In target at ambient temperature. The effects of the Ar–N2 sputtering gas mixture on the structural properties of the films were investigated by using scanning electron microscope, energy-dispersive X-ray spectroscopy, atomic force microscopy, and X-ray diffraction techniques. The optical properties of InN layers were examined by micro-Raman and Fourier transform infrared (FTIR reflectance spectroscopy at room temperature. Structural analysis specified nanocrystalline structure with crystal size of 15.87 nm, 16.65 nm, and 41.64 nm for InN films grown at N2 : Ar ratio of 100 : 0, 75 : 25, and 50 : 50, respectively. The Raman spectra indicates well defined peaks at 578, 583, and 583 cm−1, which correspond to the A1(LO phonon of the hexagonal InN films grown at gas ratios of 100 : 0, 75 : 25 and 50 : 50 N2 : Ar, respectively. Results of FTIR spectroscopy show the clearly visible TO [E1(TO] phonon mode of the InN at 479 cm−1 just for film that were deposited at 50 : 50 N2 : Ar. The X-ray diffraction results indicate that the layers consist of InN nanocrystals. The highest intensity of InN (101 peak and the best nanocrystalline InN films can be seen under the deposition condition with N2 : Ar gas mixture of 50 : 50.

  9. Chemical and structural properties of polymorphous silicon thin films grown from dichlorosilane

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez-Macías, C.; Monroy, B.M.; Huerta, L.; Canseco-Martínez, M.A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, Coyoacán, C.P. 04510 México, D.F. (Mexico); Picquart, M. [Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, A.P. 55-534, 09340 México, D.F. (Mexico); Santoyo-Salazar, J. [Departamento de Física, CINVESTAV-IPN, A.P. 14-740, C.P. 07000 México, D.F. (Mexico); Sánchez, M.F. García [Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional, Av. I.P.N. 2580, Gustavo A. Madero, 07340 México .D.F. (Mexico); Santana, G., E-mail: gsantana@iim.unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, Coyoacán, C.P. 04510 México, D.F. (Mexico)

    2013-11-15

    We have examined the effects of hydrogen dilution (R{sub H}) and deposition pressure on the morphological, structural and chemical properties of polymorphous silicon thin films (pm-Si:H), using dichlorosilane as silicon precursor in the plasma enhanced chemical vapor deposition (PECVD) process. The use of silicon chlorinated precursors enhances the crystallization process in as grown pm-Si:H samples, obtaining crystalline fractions from Raman spectra in the range of 65–95%. Atomic Force Microscopy results show the morphological differences obtained when the chlorine chemistry dominates the growth process and when the plasma–surface interactions become more prominent. Augmenting R{sub H} causes a considerable reduction in both roughness and topography, demonstrating an enhancement of ion bombardment and attack of the growing surface. X-ray Photoelectron Spectroscopy results show that, after ambient exposure, there is low concentration of oxygen inside the films grown at low R{sub H}, present in the form of Si-O, which can be considered as structural defects. Instead, oxidation increases with deposition pressure and dilution, along with film porosity, generating a secondary SiO{sub x} phase. For higher pressure and dilution, the amount of chlorine incorporated to the film decreases congruently with HCl chlorine extraction processes involving atomic hydrogen interactions with the surface. In all cases, weak silicon hydride (Si-H) bonds were not detected by infrared spectroscopy, while bonding configurations associated to the silicon nanocrystal surface were clearly observed. Since these films are generally used in photovoltaic devices, analyzing their chemical and structural properties such as oxygen incorporation to the films, along with chlorine and hydrogen, is fundamental in order to understand and optimize their electrical and optical properties.

  10. Annealing behaviors of lattice misfit in YIG and La-doped YIG films grown on GGG substrates by LPE method

    Science.gov (United States)

    Yong Choi, Duk; Jin Chung, Su

    1998-08-01

    By the LPE method using the PbO-B 2O 3 flux system, YIG and La-doped YIG films were grown on GGG substrates. Lattice misfit and defect formation could be controlled by Pb ions which were incorporated into the garnet film. The lattice misfits of as-grown and annealed samples were investigated by double and triple crystal X-ray diffractometers. Films grew pseudomorphically regardless of stress types. When the film with high Pb content was annealed, the misfit and the FWHM of the rocking curve increased. It is supposed that the increase in misfit occurs as a result of the reduction of Pb 4+ to Pb 2+, which is compensated by the formation of oxygen vacancies. During heat treatment, PbO precipitates were formed in the film, which increased FWHM of the film. For the low Pb content films, no annealing-induced change occurred.

  11. Substrate temperature influence on the properties of GaN thin films grown by hollow-cathode plasma-assisted atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Alevli, Mustafa, E-mail: mustafaalevli@marmara.edu.tr; Gungor, Neşe [Department of Physics, Faculty of Arts and Sciences, Marmara University, Goztepe, 34722 Istanbul (Turkey); Haider, Ali; Kizir, Seda; Leghari, Shahid A.; Biyikli, Necmi, E-mail: biyikli@unam.bilkent.edu.tr [Institute of Materials Science and Nanotechnology, Bilkent University, Bilkent, 06800 Ankara, Turkey and National Nanotechnology Research Center (UNAM), Bilkent University, Bilkent, 06800 Ankara (Turkey)

    2016-01-15

    Gallium nitride films were grown by hollow cathode plasma-assisted atomic layer deposition using triethylgallium and N{sub 2}/H{sub 2} plasma. An optimized recipe for GaN film was developed, and the effect of substrate temperature was studied in both self-limiting growth window and thermal decomposition-limited growth region. With increased substrate temperature, film crystallinity improved, and the optical band edge decreased from 3.60 to 3.52 eV. The refractive index and reflectivity in Reststrahlen band increased with the substrate temperature. Compressive strain is observed for both samples, and the surface roughness is observed to increase with the substrate temperature. Despite these temperature dependent material properties, the chemical composition, E{sub 1}(TO), phonon position, and crystalline phases present in the GaN film were relatively independent from growth temperature.

  12. Epitaxially grown BaM hexaferrite films having uniaxial axis in the film plane for self-biased devices.

    Science.gov (United States)

    Zhang, Xiaozhi; Meng, Siqin; Song, Dongsheng; Zhang, Yao; Yue, Zhenxing; Harris, Vincent G

    2017-03-09

    Barium hexaferrite (BaM) films with in-plane c-axis orientation are promising and technically important materials for self-biased magnetic microwave devices. In this work, highly oriented BaM films with different thickness and an in-plane easy axis (c-axis) of magnetization were grown on a-plane single-crystal sapphire substrates by direct current magnetron sputtering. A procedure involving seed layers, layer-by-layer annealing was adopted to reduce the substrate-induced strains and allow for the growth of thick (~3.44 μm) films. The epitaxial growth of the BaM film on sapphire was revealed by high-resolution transmission electron microscopy with dislocations being observed at the film-substrate interface. The orientation was also verified by X-ray diffraction and more notably, polarized Raman scattering. The magnetic properties and ferromagnetic resonant frequencies were experimentally characterized by a vibrating sample magnetometry and a frequency-swept ferromagnetic resonant flip-chip technique, respectively. The micron-thick BaM films exhibited a large remanence ratio of 0.92 along in-plane easy axis and a small one of 0.09 for the in-plane hard axis loop measurement. The FMR frequency was 50.3 GHz at zero field and reached 57.9 GHz under a magnetic field of 3 kOe, indicating that the epitaxial BaM films with strong self-biased behaviors have good electromagnetic properties in millimeter-wave range.

  13. Chemical composition of Brazilian chia seeds grown in different places.

    Science.gov (United States)

    da Silva, Bárbara Pereira; Anunciação, Pamella Cristine; Matyelka, Jessika Camila da Silva; Della Lucia, Ceres Mattos; Martino, Hércia Stampini Duarte; Pinheiro-Sant'Ana, Helena Maria

    2017-04-15

    This study investigated and compared the occurrence and concentration of macronutrients, moisture, ash, dietary fiber, fatty acids, minerals, carotenoids, vitamins, flavonoids, phenolic compounds, antioxidant activity, phytate and tannin in Brazilian chia seeds grown in the states of Mato Grosso (MT) and Rio Grande do Sul (RS). High concentrations of lipids (31.2g.100g(-1), on average), proteins (18.9g.100g(-1), on average), dietary fiber (35.3g.100g(-1), on average), vitamin E (8,203.6μg.100g(-1), on average) were observed. Similar values for total phenolic compounds and phytic acid in chia seeds from both regions were observed. Chia grown in RS showed higher antioxidant activity than chia grown in MT, and the tannin concentrations were higher in chia seeds grown in Mato Grosso (19.08±1.08eq.catequina/gsample). In conclusion, Brazilian chia seeds showed high concentrations of lipids, proteins, total dietary fiber, minerals and vitamin E. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Graphene-silica composite thin films as transparent conductors.

    Science.gov (United States)

    Watcharotone, Supinda; Dikin, Dmitriy A; Stankovich, Sasha; Piner, Richard; Jung, Inhwa; Dommett, Geoffrey H B; Evmenenko, Guennadi; Wu, Shang-En; Chen, Shu-Fang; Liu, Chuan-Pu; Nguyen, SonBinh T; Ruoff, Rodney S

    2007-07-01

    Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiOx/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing. The resulting films were characterized by SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV-vis spectroscopy, and electrical conductivity measurements. The electrical conductivity of the films compared favorably to those of composite thin films of carbon nanotubes in silica.

  15. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    CERN Document Server

    Chen, S J; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn sub 3 P sub 2. Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I sub 4) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrate...

  16. Crystallinity Improvement of ZnO Thin Film on Different Buffer Layers Grown by MBE

    Directory of Open Access Journals (Sweden)

    Shao-Ying Ting

    2012-01-01

    Full Text Available The material and optical properties of ZnO thin film samples grown on different buffer layers on sapphire substrates through a two-step temperature variation growth by molecular beam epitaxy were investigated. The thin buffer layer between the ZnO layer and the sapphire substrate decreased the lattice mismatch to achieve higher quality ZnO thin film growth. A GaN buffer layer slightly increased the quality of the ZnO thin film, but the threading dislocations still stretched along the c-axis of the GaN layer. The use of MgO as the buffer layer decreased the surface roughness of the ZnO thin film by 58.8% due to the suppression of surface cracks through strain transfer of the sample. From deep level emission and rocking curve measurements it was found that the threading dislocations play a more important role than oxygen vacancies for high-quality ZnO thin film growth.

  17. Influence of Substrate-Film Reactions on YBCO Grown by Fluorine-Free MOD Route

    DEFF Research Database (Denmark)

    Zhao, Yue; Tang, Xiao; Wu, W.

    2017-01-01

    Recently, fluorine-free metal organic deposition routes (FF-MOD) for growth of YBCO superconducting films have attracted increased attentions. In this paper, a comparison study was performed on the YBCO-Ag superconducting thin films deposited on two types substrates, LaAlO3 and CSD-Ce0.9La0.1O2-y...... (CLO)/YSZ, respectively. Although conventional TFA-MOD derived YBCO films exhibit high performance on both substrates, the results vary when using the FF-MOD precursor. SEM and XRD results reveal that c-axis and a/b-axis orientations coexist in the YBCO-Ag films grown on the CSD-CLO/YSZ substrate......-Ag films from the FF-MOD solution. Because of the different chemical reaction path compared to conventional TFA-MOD routes, it seems that the polycrystalline BaCeO3 formation takes place prior to the YBCO-Ag epitaxial growth associated with the melting process, which results in structural deterioration...

  18. Layered double hydroxides/polymer thin films grown by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Birjega, R.; Matei, A.; Mitu, B.; Ionita, M.D.; Filipescu, M.; Stokker-Cheregi, F.; Luculescu, C.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest–Magurele (Romania); Zavoianu, R.; Pavel, O.D. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest (Romania); Corobea, M.C. [National R. and S. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021, Bucharest (Romania)

    2013-09-30

    Due to their highly tunable properties, layered double hydroxides (LDHs) are an emerging class of the favorably layered crystals used for the preparation of multifunctional polymer/layered crystal nanocomposites. In contrast to cationic clay materials with negatively charge layers, LDHs are the only host lattices with positively charged layers (brucite-like), with interlayer exchangeable anions and intercalated water. In this work, the deposition of thin films of Mg and Al based LDH/polymers nanocomposites by laser techniques is reported. Matrix assisted pulsed laser evaporation was the method used for thin films deposition. The Mg–Al LDHs capability to act as a host for polymers and to produce hybrid LDH/polymer films has been investigated. Polyethylene glycol with different molecular mass compositions and ethylene glycol were used as polymers. The structure and surface morphology of the deposited LDH/polymers films were examined by X-ray diffraction, Fourier transform infra-red spectroscopy, atomic force microscopy and scanning electron microscopy. - Highlights: • Hybrid composites deposited by matrix assisted pulsed laser evaporation (MAPLE). • Mg–Al layered double hydroxides (LDH) and polyethylene glycol (PEG) are used. • Mixtures of PEG1450 and LDH were deposited by MAPLE. • Deposited thin films preserve the properties of the starting material. • The film wettability can be controlled by the amount of PEG.

  19. Acceptor states in heteroepitaxial CdHgTe films grown by molecular-beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Mynbaev, K. D.; Shilyaev, A. V., E-mail: mynkad@mail.ioffe.ru; Bazhenov, N. L. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Izhnin, A. I.; Izhnin, I. I. [R& D Institute for Materials SRC Carat (Ukraine); Mikhailov, N. N.; Varavin, V. S.; Dvoretsky, S. A. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2015-03-15

    The photoluminescence method is used to study acceptor states in CdHgTe heteroepitaxial films (HEFs) grown by molecular-beam epitaxy. A comparison of the photoluminescence spectra of HEFs grown on GaAs substrates (CdHgTe/GaAs) with the spectra of CdHgTe/Si HEFs demonstrates that acceptor states with energy depths of about 18 and 27 meV are specific to CdHgTe/GaAs HEFs. The possible nature of these states and its relation to the HEF synthesis conditions and, in particular, to the vacancy doping occurring under conditions of a mercury deficiency during the course of epitaxy and postgrowth processing are discussed.

  20. Recyclable and electrically conducting carbon nanotube composite films

    Science.gov (United States)

    Zou, Guifu; Jain, Menka; Yang, Hao; Zhang, Yingying; Williams, Darrick; Jia, Quanxi

    2010-03-01

    Carbon nanotube (CNT) composite films possess unique electrical, mechanical and thermal properties. In particular, some research has shown that CNT-polymer composite films greatly enhance the performance of organic light-emitting diodes. Therefore, CNT composite films have been intensively fabricated and applied. However, recent research has shown that CNTs carry carcinogenic risks in vivo. Therefore, how to collect and treat damaged or trashed CNT composite films are considerable tasks for scientists working in this area. From the viewpoint of environmental protection and saving resources, recycling the CNT composite films is the most efficient way to solve these problems. Here, we employ a benign water-soluble polymer, polyethyleneimine (PEI), to disperse CNTs and a general spin-coating process to prepare the homogeneous CNT composite films. The prepared CNT composite films exhibit good water-soluble properties and recyclability, i.e. they can be formed and dissolved in water. In addition, the long CNTs and high loading in the PEI matrix facilitates good electric conductivity in these CNT composite films. A significant improvement in the conductivity of the composite films is observed as the concentration of CNTs in the PEI increases, reaching as high as 43.73 S cm-1 when the CNT concentration is equal to 3%.

  1. Morphological and microstructural stability of N-polar InAlN thin films grown on free-standing GaN substrates by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, Matthew T., E-mail: matthew.hardy.ctr@nrl.navy.mil; Storm, David F.; Downey, Brian P.; Katzer, D. Scott; Meyer, David J. [Electronics Science and Technology Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington DC 20375 (United States); McConkie, Thomas O.; Smith, David J. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Nepal, Neeraj [Sotera Defense Solutions, 2200 Defense Hwy Suite 405, Crofton, Maryland 21114 (United States)

    2016-03-15

    The sensitivity of the surface morphology and microstructure of N-polar-oriented InAlN to variations in composition, temperature, and layer thickness for thin films grown by plasma-assisted molecular beam epitaxy (PAMBE) has been investigated. Lateral compositional inhomogeneity is present in N-rich InAlN films grown at low temperature, and phase segregation is exacerbated with increasing InN fraction. A smooth, step-flow surface morphology and elimination of compositional inhomogeneity can be achieved at a growth temperature 50 °C above the onset of In evaporation (650 °C). A GaN/AlN/GaN/200-nm InAlN heterostructure had a sheet charge density of 1.7 × 10{sup 13 }cm{sup −2} and no degradation in mobility (1760 cm{sup 2}/V s) relative to 15-nm-thick InAlN layers. Demonstration of thick-barrier high-electron-mobility transistors with good direct-current characteristics shows that device quality, thick InAlN layers can be successfully grown by PAMBE.

  2. Resistive memory switching in ultrathin TiO{sub 2} films grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, V. K., E-mail: vikassahu@rrcat.gov.in; Misra, P.; Ajimsha, R. S.; Das, A. K.; Joshi, M. P.; Kukreja, L. M. [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2016-05-23

    Electric field controlled forming free and unipolar resistive memory switching was observed in Au/TiO{sub 2}/Pt devices containing ultrathin TiO{sub 2} films of thickness ~ 4 nm grown by atomic layer deposition. These devices showed a large resistance ratio of ~ 10{sup 3} between high and low resistance states along with appreciable time retention for ~ 10{sup 4} seconds and endurance. The spread of reset and set voltages was from ~ 0.4-0.6 V and 1.1-1.5 V respectively with a clear window between them. The resistive switching mechanism was explained based on conductive filamentary model.

  3. SEM, EDS, PL and absorbance study of CdTe thin films grown by CSS method

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Torres, M.E.; Silva-Gonzalez, R.; Gracia-Jimenez, J.M. [Instituto de Fisica, BUAP, Apdo. Postal J-48, San Manuel, 72570 Puebla, Pue. (Mexico); Casarrubias-Segura, G. [CIE- UNAM, 62580 Temixco, Morelos (Mexico)

    2006-09-22

    Oxygen-doped CdTe films were grown on conducting glass substrates by the close spaced sublimation (CSS) method and characterized using SEM, EDS, photoluminescence (PL) and absorbance. A significant change in the polycrystalline morphology is observed when the oxygen proportion is increased in the deposition atmosphere. The EDS analysis showed that all samples are nonstoichiometric with excess Te. The PL spectra show emission bands associated with Te vacancies (V{sub Te}), whose intensities decrease as the oxygen proportion in the CSS chamber is increased. The oxygen impurities occupy Te vacancies and modify the surfaces states, improving the nonradiative process. (author)

  4. Lutetium-doped EuO films grown by molecular-beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Melville, A.; Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Mairoser, T.; Schmehl, A. [Zentrum fuer elektronische Korrelationen und Magnetismus, Universitaet Augsburg, Universitaetsstrasse 1, D-86159 Augsburg (Germany); Shai, D. E.; Monkman, E. J.; Harter, J. W. [Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Hollaender, B.; Schubert, J. [Peter Gruenberg Institute, PGI 9-IT, JARA-FIT, Research Centre Juelich, D-52425 Juelich (Germany); Shen, K. M. [Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States); Mannhart, J. [Max Planck Institute for Solid State Research, D-70569 Stuttgart (Germany); Schlom, D. G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

    2012-05-28

    The effect of lutetium doping on the structural, electronic, and magnetic properties of epitaxial EuO thin films grown by reactive molecular-beam epitaxy is experimentally investigated. The behavior of Lu-doped EuO is contrasted with doping by lanthanum and gadolinium. All three dopants are found to behave similarly despite differences in electronic configuration and ionic size. Andreev reflection measurements on Lu-doped EuO reveal a spin-polarization of 96% in the conduction band, despite non-magnetic carriers introduced by 5% lutetium doping.

  5. Microstructures of GaN thin films grown on graphene layers.

    Science.gov (United States)

    Yoo, Hyobin; Chung, Kunook; Choi, Yong Seok; Kang, Chan Soon; Oh, Kyu Hwan; Kim, Miyoung; Yi, Gyu-Chul

    2012-01-24

    Plan-view and cross-sectional transmission electron microscopy images show the microstructural properties of GaN thin films grown on graphene layers, including dislocation types and density, crystalline orientation and grain boundaries. The roles of ZnO nanowalls and GaN intermediate layers in the heteroepitaxial growth of GaN on graphene, revealed by cross-sectional transmission electron microscopy, are also discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Effect of annealing on pulse laser deposition grown copper oxide thin film

    Science.gov (United States)

    Mistry, Vaibhavi H.; Mistry, Bhaumik V.; Modi, B. P.; Joshi, U. S.

    2017-05-01

    Cuprous oxide (Cu2O) is a promising non-toxic and low cost semiconductor with potential applications in photovoltaic devices and sensor applications. Copper oxide thin films were prepared on glass substrate by pulse laser deposition. The effects of annealing on the structural, optical and electrical properties of copper oxide thin films were studied. The films were annealed in air for different temperature ranging from 200 to 450 °C. X-ray diffraction patterns reveals that the films as-deposited and annealed at 200 and 250 °C are of cuprite structure with composition Cu2O. Annealing at 300 °C and above converts these films to CuO phase. The atomic force microscopy results show that both the phase has nanocrystalline and particle size of the films is increasing with increase in annealing temperature. The conversion from Cu2O to CuO phase was confirmed by a shift in the optical band gap from 2.20 eV to 1.74 eV. The annealing conditions play a major role in the structural properties of copper oxide thin films.

  7. Characterization of conducting polymer films grown via surface polymerization by ion-assisted deposition

    Science.gov (United States)

    Tepavcevic, Sanja

    2006-04-01

    Optimization of photonic and electronic devices based on conductive polymers, such as polythiophene and polyphenyl, requires the development of processing methods that can control both film chemistry and morphology on the nanoscale. One such method is explored in this thesis: surface polymerization by ion-assisted deposition (SPIAD). Polythiophene and polyphenyl thin films are grown on a silicon surface by SPIAD which uses hyperthermal, mass-selected thiophene cations coincident with alpha-thermal beam of aterthiophene (3T) or p-terphenyl (3P) neutrals. Mass spectrometry and x-ray photoelectron spectroscopy are used to verify polymerization of both 3T and 3P. The optimal conditions for the most efficient polymerization reaction and film growth are found by varying ion/neutral ratio and ion energy. The electronic structures of these films are probed by ultraviolet photoelectron spectroscopy (UPS) and polarized near-edge x-ray absorption fine structure spectroscopy (NEXAFS). The conducting polymer films formed by SPIAD display new valence band features resulting from a reduction in both their band gap and barrier to hole injection. These changes in film electronic structure result from an increase in the electron conjugation length and other changes in film structure induced by SPIAD. Scanning electron microscopy and x-ray diffraction are used to demonstrate that SPIAD can control the overall polythiophene and polyphenyl film morphology through the mediation of adsorption, diffusion, sublimation (desorption), and other thermal film growth events by ion-induced processes including polymerization, sputtering, bond breakage, and energetic mixing. Predicting the electronic properties, growth mechanism and morphology of the SPIAD films should be possible through computer simulations of the controlling phenomenon. Study with first principles density functional theory-molecular dynamics (DFT-MD) simulations indicates that polymerization and fragmentation of ions and

  8. Electrochemical delamination of CVD-grown graphene film: toward the recyclable use of copper catalyst.

    Science.gov (United States)

    Wang, Yu; Zheng, Yi; Xu, Xiangfan; Dubuisson, Emilie; Bao, Qiaoliang; Lu, Jiong; Loh, Kian Ping

    2011-12-27

    The separation of chemical vapor deposited (CVD) graphene from the metallic catalyst it is grown on, followed by a subsequent transfer to a dielectric substrate, is currently the adopted method for device fabrication. Most transfer techniques use a chemical etching method to dissolve the metal catalysts, thus imposing high material cost in large-scale fabrication. Here, we demonstrate a highly efficient, nondestructive electrochemical route for the delamination of CVD graphene film from metal surfaces. The electrochemically delaminated graphene films are continuous over 95% of the surface and exhibit increasingly better electronic quality after several growth cycles on the reused copper catalyst, due to the suppression of quasi-periodical nanoripples induced by copper step edges. The electrochemical delamination process affords the advantages of high efficiency, low-cost recyclability, and minimal use of etching chemicals.

  9. Induced polarized state in intentionally grown oxygen deficient KTaO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mota, D. A.; Romaguera-Barcelay, Y.; Tkach, A.; Agostinho Moreira, J.; Almeida, A. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science of University of Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Perez de la Cruz, J. [INESC TEC, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Vilarinho, P. M. [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Tavares, P. B. [Centro de Quimica, Universidade de Tras-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real (Portugal)

    2013-07-21

    Deliberately oxygen deficient potassium tantalate thin films were grown by RF magnetron sputtering on Si/SiO{sub 2}/Ti/Pt substrates. Once they were structurally characterized, the effect of oxygen vacancies on their electric properties was addressed by measuring leakage currents, dielectric constant, electric polarization, and thermally stimulated depolarization currents. By using K{sub 2}O rich KTaO{sub 3} targets and specific deposition conditions, KTaO{sub 3-{delta}} oxygen deficient thin films with a K/Ta = 1 ratio were obtained. Room temperature X-ray diffraction patterns show that KTaO{sub 3-{delta}} thin films are under a compressive strain of 2.3% relative to KTaO{sub 3} crystals. Leakage current results reveal the presence of a conductive mechanism, following the Poole-Frenkel formalism. Furthermore, dielectric, polarization, and depolarization current measurements yield the existence of a polarized state below T{sub pol} {approx} 367 Degree-Sign C. A Cole-Cole dipolar relaxation was also ascertained apparently due to oxygen vacancies induced dipoles. After thermal annealing the films in an oxygen atmosphere at a temperature above T{sub pol}, the aforementioned polarized state is suppressed, associated with a drastic oxygen vacancies reduction emerging from annealing process.

  10. Thermal stability of MBE-grown epitaxial MoSe2 and WSe2 thin films

    Science.gov (United States)

    Chang, Young Jun; Choy, Byoung Ki; Phark, Soo-Hyon; Kim, Minu

    Layered transition metal dichalcogenides (TMDs) draw much attention, because of its unique optical properties and band structures depending on the layer thicknesses. However, MBE growth of epitaxial films demands information about thermal stability of stoichiometry and related electronic structure for high temperature range. We grow epitaxial MoSe2 and WSe2 ultrathin films by using molecular beam epitaxy (MBE). We characterize stoichiometry of films grown at various growth temperature by using various methods, XPS, EDX, and TOF-MEIS. We further test high temperature stability of electronic structure for those films by utilizing in-situ ellipsometry attached to UHV chamber. We discuss threshold temperatures up to 700~1000oC, at which electronic phases changes from semiconductor to metal due to selenium deficiency. This information can be useful for potential application of TMDs for fabrication of Van der Waals multilayers and related devices. This research was supported by Nano.Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning. (2009-0082580), NRF-2014R1A1A1002868.

  11. Effect of the burning temperature on the phase composition, photovoltaic response, and electrical properties of Ag/Pd resistive films

    Science.gov (United States)

    Mikheev, G. M.; Saushin, A. S.; Goncharov, O. Yu.; Dorofeev, G. A.; Gil'mutdinov, F. Z.; Zonov, R. G.

    2014-11-01

    Silver-palladium (Ag/Pd) films were grown by thick-film technology using a resistive paste consisting of Pd, Ag2O, and glass on ceramic substrates at burning temperatures of 878, 1013, and 1113 K. The effect of the burning temperature and Pd content in the initial paste on the phase composition, resistivity, photovoltaic properties of films, free carrier concentration, and mobility was studied. It was found that the films grown at a burning temperature of 878 K have the greatest factor of conversion of the pulsed laser power to the photovoltaic signal, which depends on the direction of the incident radiation wave vector. Using X-ray diffraction, X-ray photoelectron spectroscopy, and thermodynamic modeling, it was shown that the AgPd alloy and PdO oxide are the main components of the Ag/Pd film with photovoltaic properties.

  12. Thermoelectric properties of Bi0.5Sb1.5Te3 thin films grown by pulsed laser deposition

    Science.gov (United States)

    Symeou, E.; Pervolaraki, M.; Mihailescu, C. N.; Athanasopoulos, G. I.; Papageorgiou, Ch.; Kyratsi, Th.; Giapintzakis, J.

    2015-05-01

    We report on the pulsed laser deposition of p-type Bi0.5Sb1.5Te3 thin films onto fused silica substrates by ablation of dense targets of Bi0.5Sb1.5Te3 with an excess of 1 wt% Te. We investigated the effect of film thickness, substrate temperature and post-annealing duration on the thermoelectric properties of the films. Our results show that the best power factor (2780 μW/K2m at 300 K) is obtained for films grown at room temperature and then post-annealed in vacuum at 300 °C for 16 h. This is among the highest power factor values reported for Bi0.5Sb1.5Te3 films grown on fused silica substrates.

  13. Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution

    KAUST Repository

    Faber, Hendrik

    2017-04-28

    Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In2O3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In2O3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications.

  14. Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution.

    Science.gov (United States)

    Faber, Hendrik; Das, Satyajit; Lin, Yen-Hung; Pliatsikas, Nikos; Zhao, Kui; Kehagias, Thomas; Dimitrakopulos, George; Amassian, Aram; Patsalas, Panos A; Anthopoulos, Thomas D

    2017-03-01

    Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In2O3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In2O3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications.

  15. Atomic Layer Deposition (ALD) grown thin films for ultra-fine pitch pixel detectors

    Energy Technology Data Exchange (ETDEWEB)

    Härkönen, J. [Helsinki Institute of Physics, CMS Upgrade Project, Helsinki (Finland); Ott, J. [Helsinki Institute of Physics, CMS Upgrade Project, Helsinki (Finland); Laboratory of Radio Chemistry, University of Helsinki (Finland); Mäkelä, M. [Laboratory of Inorganic Chemistry, University of Helsinki (Finland); Arsenovich, T.; Gädda, A.; Peltola, T. [Helsinki Institute of Physics, CMS Upgrade Project, Helsinki (Finland); Tuovinen, E. [Helsinki Institute of Physics, CMS Upgrade Project, Helsinki (Finland); VTT Technical Research Centre of Finland, Microsystem and Nanoelectronics (Finland); Luukka, P.; Tuominen, E. [Helsinki Institute of Physics, CMS Upgrade Project, Helsinki (Finland); Junkes, A. [Institute for Experimental Physics, University of Hamburg (Germany); Niinistö, J.; Ritala, M. [Laboratory of Inorganic Chemistry, University of Helsinki (Finland)

    2016-09-21

    In this report we cover two special applications of Atomic Layer Deposition (ALD) thin films to solve these challenges of the very small size pixel detectors. First, we propose to passivate the p-type pixel detector with ALD grown Al{sub 2}O{sub 3} field insulator with a negative oxide charge instead of using the commonly adopted p-stop or p-spray technologies with SiO{sub 2}, and second, to use plasma-enhanced ALD grown titanium nitride (TiN) bias resistors instead of the punch through biasing structures. Surface passivation properties of Al{sub 2}O{sub 3} field insulator was studied by Photoconductive Decay (PCD) method and our results indicate that after appropriate annealing Al{sub 2}O{sub 3} provides equally low effective surface recombination velocity as thermally oxidized Si/SiO{sub 2} interface. Furthermore, with properly designed annealing steps, the TiN thin film resistors can be tuned to have up to several MΩ resistances with a few µm of physical size required in ultra-fine pitch pixel detectors.

  16. The frequency-dependent AC photoresistance behavior of ZnO thin films grown on different sapphire substrates.

    Science.gov (United States)

    Cholula-Díaz, Jorge L; Barzola-Quiquia, José; Videa, Marcelo; Yin, Chunhai; Esquinazi, Pablo

    2017-09-13

    Zinc oxide (ZnO) thin films were grown by pulsed layer deposition under an N 2 atmosphere at low pressures on a- and r-plane sapphire substrates. Structural studies using X-ray diffraction confirmed that all films had a wurtzite phase. ZnO thin films on a- and r-plane sapphire have grown with orientations along the [0002] and [112[combining macron]0] directions, respectively. Room temperature photoluminescence measurements indicate that the presence of native point defects (interstitial zinc, oxygen vacancies, oxygen antisites and zinc vacancies) is more preponderant for ZnO thin films grown on the r-plane sapphire substrate than the sample grown on the a-plane sapphire substrate. Room temperature impedance spectroscopy measurements were performed in an alternating current frequency range from 40 to 10 5 Hz in the dark and under normal light. An unusual positive photoresistance effect is observed at frequencies above 100 kHz, which we suggest to be due to intrinsic defects present in the ZnO thin films. Furthermore, an analysis of the optical time response revealed that the film grown on the r-plane sapphire substrate responds faster (characteristic relaxation times for τ 1 , τ 2 and τ 3 of 0.05, 0.26 and 6.00 min, respectively) than the film grown on the a-plane sapphire substrate (characteristic relaxation times for τ 1 , τ 2 and τ 3 of 0.10, 0.73 and 4.02 min, respectively).

  17. Structural, electrical and optical properties of indium tin oxide thin film grown by metal organic chemical vapor deposition with tetramethyltin-precursor

    Science.gov (United States)

    Zhuo, Yi; Chen, Zimin; Tu, Wenbin; Ma, Xuejin; Wang, Gang

    2018-01-01

    Tin-doped indium oxide (ITO) is grown by metal organic chemical vapor deposition (MOCVD) using tetramethyltin (TDMASn) as tin precursor. The as-grown ITO films are polycrystalline with (111) and (100) textures. A gradual transition of crystallographic orientation from (111) preferred to (100) preferred is observed as the composition of tin changes. By precisely controlling the Sn doping, the ITO thin films present promising optical and electrical performances at either near-infrared-visible or visible-near-ultraviolet ranges. At low Sn doping level, the as-grown ITO possesses high electron mobility of 48.8 cm2 V‑1 s‑1, which results in high near-infrared transmittance and low resistivity. At higher Sn doping level, high carrier concentration (8.9 × 1020 cm‑3) and low resistivity (3 × 10‑4 Ω cm) are achieved. The transmittance is 97.8, 99.1, and 82.3% at the wavelength of 550, 365, and 320 nm, respectively. The results strongly suggest that MOCVD with TDMASn as tin precursor is an effective method to fabricate high quality ITO thin film for near-infrared, visible light, and near-ultraviolet application.

  18. Optical absorption properties of Ag/SiO sub 2 composite films induced by gamma irradiation

    CERN Document Server

    Pan, A L; Yang, Z P; Liu, F X; Ding, Z J; Qian, Y T

    2003-01-01

    Mesoporous SiO sub 2 composite films with small Ag particles or clusters dispersed in them were prepared by a new method: first the matrix SiO sub 2 films were prepared by the sol-gel process combined with the dip-coating technique; then they were soaked in AgNO sub 3 solutions; this was followed by irradiation with gamma-rays at room temperature and ambient pressure. The structure of these films was examined by high-resolution transmission electron microscopy, and their optical absorption spectra were examined. It has been shown that the Ag particles grown within the porous SiO sub 2 films are very small and are highly dispersed. On increasing the soaking concentration and subjecting the samples to an additional annealing, a different peak-shift effect for the surface plasmon resonance was observed in the optical absorption measurement. Possible mechanisms of this behaviour are discussed in this paper.

  19. Properties of anodic oxides grown on a hafnium–tantalum–titanium thin film library

    Directory of Open Access Journals (Sweden)

    Andrei Ionut Mardare

    2014-01-01

    Full Text Available A ternary thin film combinatorial materials library of the valve metal system Hf–Ta–Ti obtained by co-sputtering was studied. The microstructural and crystallographic analysis of the obtained compositions revealed a crystalline and textured surface, with the exception of compositions with Ta concentration above 48 at.% which are amorphous and show a flat surface. Electrochemical anodization of the composition spread thin films was used for analysing the growth of the mixed surface oxides. Oxide formation factors, obtained from the potentiodynamic anodization curves, as well as the dielectric constants and electrical resistances, obtained from electrochemical impedance spectroscopy, were mapped along two dimensions of the library using a scanning droplet cell microscope. The semiconducting properties of the anodic oxides were mapped using Mott–Schottky analysis. The degree of oxide mixing was analysed qualitatively using x-ray photoelectron spectroscopy depth profiling. A quantitative analysis of the surface oxides was performed and correlated to the as-deposited metal thin film compositions. In the concurrent transport of the three metal cations during oxide growth a clear speed order of Ti > Hf > Ta was proven.

  20. Characteristics of CuInSe sub 2 thin films grown by the selenization method

    CERN Document Server

    Kim, S D; Adurodija, F O; Yoon, K H; Song, J S

    1999-01-01

    CuInSe sub 2 thin films were formed from a selenization of co-sputtered Cu-In alloy layers which consisted of only two phases, CuIn sub 2 and Cu sub 1 sub 1 In sub 9. A linear dependence of the Cu-In alloy film composition on the Cu/In sputtering power was found. The metallic layers were selenized in vacuum or at 1 atm. A small number of Cu-Se and In-Se compounds was observed during the early stage of selenization, and single-phase CuInSe sub 2 was more easily formed in vacuum than at atmospheric pressure. Therefore, CuInSe sub 2 films selenized in vacuum showed larger grain sizes, smoother surfaces, and denser microstructures than those selenized at 1 atm.

  1. Structural Properties Characterized by the Film Thickness and Annealing Temperature for La2O3 Films Grown by Atomic Layer Deposition

    Science.gov (United States)

    Wang, Xing; Liu, Hongxia; Zhao, Lu; Fei, Chenxi; Feng, Xingyao; Chen, Shupeng; Wang, Yongte

    2017-03-01

    La2O3 films were grown on Si substrates by atomic layer deposition technique with different thickness. Crystallization characteristics of the La2O3 films were analyzed by grazing incidence X-ray diffraction after post-deposition rapid thermal annealing treatments at several annealing temperatures. It was found that the crystallization behaviors of the La2O3 films are affected by the film thickness and annealing temperatures as a relationship with the diffusion of Si substrate. Compared with the amorphous La2O3 films, the crystallized films were observed to be more unstable due to the hygroscopicity of La2O3. Besides, the impacts of crystallization characteristics on the bandgap and refractive index of the La2O3 films were also investigated by X-ray photoelectron spectroscopy and spectroscopic ellipsometry, respectively.

  2. Fluence dependent electrical conductivity in aluminium thin films grown by infrared pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rebollar, Esther, E-mail: e.rebollar@csic.es [Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 19, 28006 Madrid (Spain); Martínez-Tong, Daniel E. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Sanz, Mikel; Oujja, Mohamed; Marco, José F. [Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 19, 28006 Madrid (Spain); Ezquerra, Tiberio A. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Castillejo, Marta [Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 19, 28006 Madrid (Spain)

    2016-11-30

    Highlights: • IR pulsed laser ablation of aluminium gives rise to smooth layers of several tens of nanometers. • Irradiation at fluences around 2.7 J/cm{sup 2} and above 7 J/cm{sup 2} resulted in deposition of amorphous aluminium oxide films and metallic aluminium films respectively. • Highly ionized species are more abundant in the ablation plumes generated at higher fluences. • It is possible to control by PLD the metal or dielectric character of the films. - Abstract: We studied the effect of laser fluence on the morphology, composition, structure and electric conductivity of deposits generated by pulsed laser ablation of a metallic aluminium target in vacuum using a Q-switched Nd:YAG laser (1064 nm, 15 ns). Upon irradiation for one hour at a repetition rate of 10 Hz, a smooth layer of several tens of nanometres, as revealed by atomic force microscopy (AFM) was deposited on glass. Surface chemical composition was determined by X-ray photoelectron spectroscopy, and to study the conductivity of deposits both I–V curves and conductive-AFM measurements were performed. Irradiation at fluences around 2.7 J/cm{sup 2} resulted in deposition of amorphous aluminium oxide films. Differently, at higher fluences above 7 J/cm{sup 2}, the films are constituted by metallic aluminium. Optical emission spectroscopy revealed that highly ionized species are more abundant in the ablation plumes generated at higher fluences. The results demonstrate the possibility to control by PLD the metal or dielectric character of the films.

  3. Enhanced stability and mechanical strength of sodium alginate composite films.

    Science.gov (United States)

    Liu, Sijun; Li, Yong; Li, Lin

    2017-03-15

    This work aims to study how three kinds of nanofillers: graphene oxide (GO), ammonia functionalized graphene oxide (AGO), and triethoxylpropylaminosilane functionalized silica, can affect stability and mechanical strength of sodium alginate (SA) composite films. The filler/sodium alginate (SA) solutions were first studied by rheology to reveal effects of various fillers on zero shear viscosity η0. SA composite films were then prepared by a solution mixing-evaporation method. The structure, morphology and properties of SA composite films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), contact angle and mechanical testing. Compared to GO and silica, the presence of AGO significantly improved the interaction between AGO and SA, which led to the increase in stability and mechanical strength of the resulting SA composite films. The tensile strength and elongation at break of AGO/SA composite film at 3wt% AGO loading were increased by 114.9% and 194.4%, respectively, in contrast to pure SA film. Furthermore, the stability of AGO/SA composite films at high temperatures and in a wet environment were better than that of silica/SA and GO/SA composite films. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. A kinetic model for stress generation in thin films grown from energetic vapor fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Chason, E.; Karlson, M. [School of Engineering, Brown University, Providence, Rhode Island 02912 (United States); Colin, J. J.; Abadias, G. [Institut P' , Département Physique et Mécanique des Matériaux, Université de Poitiers-CNRS-ENSMA, SP2MI, Téléport 2, Bd M. et P. Curie, F-86962 Chasseneuil-Futuroscope (France); Magnfält, D.; Sarakinos, K. [Nanoscale Engineering Division, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden)

    2016-04-14

    We have developed a kinetic model for residual stress generation in thin films grown from energetic vapor fluxes, encountered, e.g., during sputter deposition. The new analytical model considers sub-surface point defects created by atomic peening, along with processes treated in already existing stress models for non-energetic deposition, i.e., thermally activated diffusion processes at the surface and the grain boundary. According to the new model, ballistically induced sub-surface defects can get incorporated as excess atoms at the grain boundary, remain trapped in the bulk, or annihilate at the free surface, resulting in a complex dependence of the steady-state stress on the grain size, the growth rate, as well as the energetics of the incoming particle flux. We compare calculations from the model with in situ stress measurements performed on a series of Mo films sputter-deposited at different conditions and having different grain sizes. The model is able to reproduce the observed increase of compressive stress with increasing growth rate, behavior that is the opposite of what is typically seen under non-energetic growth conditions. On a grander scale, this study is a step towards obtaining a comprehensive understanding of stress generation and evolution in vapor deposited polycrystalline thin films.

  5. Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films

    Science.gov (United States)

    Schüffelgen, Peter; Rosenbach, Daniel; Neumann, Elmar; Stehno, Martin P.; Lanius, Martin; Zhao, Jialin; Wang, Meng; Sheehan, Brendan; Schmidt, Michael; Gao, Bo; Brinkman, Alexander; Mussler, Gregor; Schäpers, Thomas; Grützmacher, Detlev

    2017-11-01

    Topological insulator (Bi0.06Sb0.94)2Te3 thin films grown by molecular beam epitaxy have been capped in-situ with a 2 nm Al film to conserve the pristine topological surface states. Subsequently, a shadow mask - structured by means of focus ion beam - was in-situ placed underneath the sample to deposit a thick layer of Al on well-defined microscopically small areas. The 2 nm thin Al layer fully oxidizes after exposure to air and in this way protects the TI surface from degradation. The thick Al layer remains metallic underneath a 3-4 nm thick native oxide layer and therefore serves as (super-) conducting contacts. Superconductor-Topological Insulator-Superconductor junctions with lateral dimensions in the nm range have then been fabricated via an alternative stencil lithography technique. Despite the in-situ deposition, transport measurements and transmission electron microscope analysis indicate a low transparency, due to an intermixed region at the interface between topological insulator thin film and metallic Al.

  6. IR emission and electrical conductivity of Nd/Nb-codoped TiO{sub x} (1.5 < x < 2) thin films grown by pulsed-laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tchiffo-Tameko, C.; Cachoncinlle, C. [GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2 (France); Perriere, J. [Sorbonne Universités, UPMC Université Paris 06, UMR 7588, INSP, 75005 Paris (France); CNRS, UMR 7588, INSP, 75005 Paris (France); Nistor, M. [NILPRP, L 22 P.O. Box MG-36, 77125 Bucharest-Magurele (Romania); Petit, A.; Aubry, O. [GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2 (France); Pérez Casero, R. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Millon, E., E-mail: eric.millon@univ-orleans.fr [GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2 (France)

    2016-12-15

    Highlights: • Nd/Nb-codoped TiO{sub 2} PLD films are electrically insulating and transparent in the UV visible NIR spectral domain. • Nd/Nb-codoped oxygen deficient TiO{sub x} (x ≈ 1.5) films are conductive and absorbent. • IR emission of Nd{sup 3+} in codoped TiO{sub x} films is quenched due to oxygen deficiency. • High Nb-doping rate decreases the IR emission of Nd{sup 3+} in Nd/Nb-codoped TiO{sub 2} films. - Abstract: The effect of the co-doping with Nd and Nb on electrical and optical properties of TiO{sub x} films is reported. The role of oxygen vacancies on the physical properties is also evidenced. The films are grown by pulsed-laser deposition onto (001) sapphire and (100) silicon substrates. The substrate temperature was fixed at 700 °C. To obtain either stoichiometric (TiO{sub 2}) or highly oxygen deficient (TiO{sub x} with x < 1.6) thin films, the oxygen partial pressure was adjusted at 10{sup −1} and 10{sup −6} mbar, respectively. 1%Nd-1%Nb, 1%Nd-5%Nb and 5%Nd-1%Nb co-doped TiO{sub 2} were used as bulk ceramic target. Composition, structural and morphological properties of films determined by Rutherford backscattering spectroscopy, X-ray diffraction and scanning electron microscopy, are correlated to their optical (UV–vis transmission and photoluminescence) and electrical properties (resistivity at room temperature). The most intense Nd{sup 3+} emission in the IR domain is obtained for stoichiometric films. Codoping Nd-TiO{sub x} films by Nb{sup 5+} ions is found to decrease the photoluminescence efficiency. The oxygen pressure during the growth allows to tune the optical and electrical properties: insulating and highly transparent (80% in the visible range) Nd/Nb codoped TiO{sub 2} films are obtained at high oxygen pressure, while conductive and absorbent films are grown under low oxygen pressure (10{sup −6} mbar).

  7. Comparison and semiconductor properties of nitrogen doped carbon thin films grown by different techniques

    Energy Technology Data Exchange (ETDEWEB)

    Alibart, F.; Drouhin, O. Durand [Laboratoire e Physique de la Matiere Condensee, 33 rue Saint Leu, 80000 Amiens (France); Benlahsen, M. [Laboratoire e Physique de la Matiere Condensee, 33 rue Saint Leu, 80000 Amiens (France)], E-mail: mohamed.benlahsen@sc.u-picardie.fr; Muhl, S.; Rodil, S. Elizabeth [Instituo de Investigationes en Materials, Universidad National Autonomia de Mexico, Mexico, D.F. 04510 (Mexico); Camps, E.; Escobar-Alarcon, L. [Instituo National de Investigationes Nucleares, Apdo. Postal 18-1027, Mexico, D.F. 11801 (Mexico)

    2008-06-30

    Amorphous carbon nitride (a-CN{sub x}) thin films have been synthesised by three different deposition techniques in an Ar/N{sub 2} gas mixture and have been deposited by varying the percentage of nitrogen gas in the mixture (i.e. the N{sub 2}/Ar + N{sub 2} ratio) from 0 to 10%. The variation of the electrical conductivity and the gap values of the deposited films versus the N{sub 2}/Ar + N{sub 2} ratio were investigated in relation with their local microstructure. Film composition was analysed using Raman spectroscopy and optical transmission experiments. The observed variation of electrical conductivity and optical properties are attributed to the changes in the atomic bonding structures, which were induced by N incorporation, increasing both the sp{sup 2} carbon content and their relative disorder. The low N content samples seem to be an interesting material to produce films with interesting properties for optoelectronic applications considering the facility to control the gas composition as a key parameter.

  8. Thermal stability and relaxation mechanisms in compressively strained Ge{sub 0.94}Sn{sub 0.06} thin films grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Fleischmann, C.; Lieten, R. R.; Shimura, Y.; Vandervorst, W. [Instituut voor Kern-en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); imec, Kapeldreef 75, 3001 Leuven (Belgium); Hermann, P.; Hönicke, P.; Beckhoff, B. [Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin (Germany); Seidel, F. [Instituut voor Kern-en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); imec, Kapeldreef 75, 3001 Leuven (Belgium); Institut für Elektronik-und Sensormaterialien, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 3, 09599 Freiberg (Germany); Richard, O.; Bender, H. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Zaima, S. [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Uchida, N. [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba West SCR, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Temst, K.; Vantomme, A. [Instituut voor Kern-en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium)

    2016-08-28

    Strained Ge{sub 1-x}Sn{sub x} thin films have recently attracted a lot of attention as promising high mobility or light emitting materials for future micro- and optoelectronic devices. While they can be grown nowadays with high crystal quality, the mechanism by which strain energy is relieved upon thermal treatments remains speculative. To this end, we investigated the evolution (and the interplay) of composition, strain, and morphology of strained Ge{sub 0.94}Sn{sub 0.06} films with temperature. We observed a diffusion-driven formation of Sn-enriched islands (and their self-organization) as well as surface depressions (pits), resulting in phase separation and (local) reduction in strain energy, respectively. Remarkably, these compositional and morphological instabilities were found to be the dominating mechanisms to relieve energy, implying that the relaxation via misfit generation and propagation is not intrinsic to compressively strained Ge{sub 0.94}Sn{sub 0.06} films grown by molecular beam epitaxy.

  9. The investigation of spray pyrolysis grown CdS thin films doped with flourine atoms

    Energy Technology Data Exchange (ETDEWEB)

    Yılmaz, Salih, E-mail: slh_yilmaz@yahoo.com.tr

    2015-12-01

    Highlights: • Undoped and F-doped CdS thin films were produced. • XRD data showed deterioration with the increase of F-doping. • SEM images indicated a grain growth after F-doping. • RTPL data exhibited an enhancement in the spectrum for F-doped CdS samples. • The best electrical and optical properties were obtained for 2 at.% F-doped CdS. - Abstract: Undoped and F-doped CdS thin films were succesfully grown on the glass substrates by the spray prolysis method. X-ray diffraction results showed that all the samples had hexagonal wurtzite structure with the (1 0 1) preferred orientation. It was found from scanning electron microscopy that an increase in the grain size was observed after F-doping. The band gap value of CdS thin films increased from 2.38 eV to 2.42 eV with the increase of F concentration from 0 to 6 at.%. The intensity of room temperature photoluminescence spectrum of undoped CdS thin films enhanced with the increment of F-doping amount that is related to the increase of point defects formed by the flourine atoms. Electrical measurements showed that the carrier concentration increased from 1.93 × 10{sup 12} cm{sup −3} to 7.62 × 10{sup 12} cm{sup −3} when CdS thin films were doped with 2 at.% F. However, further increase in F amount up to 6 at.% caused a decrease in the carrier concentration. On the other hand, resistivity value first decreased from 1.26 × 10{sup 5} Ω cm to 8.54 × 10{sup 4} Ω cm with the increase of F-doping up to 2 at.% and then increased to 1.65 × 10{sup 5} Ω cm for 6 at.% F-doping. It can be concluded that 2 at.% F-doped CdS thin films exhibited the best electrical and optical properties, which is suitable for the application of thin film solar cells.

  10. Gallium and indium co-doping of epitaxial zinc oxide thin films grown in water at 90 °C

    Science.gov (United States)

    Quang Le, Hong; Chua, Soo Jin

    2011-03-01

    Zinc oxide (ZnO) thin films were intentionally co-doped with group III elements (gallium) in order to investigate and understand the effects of co-doping on the morphological, electrical and optical properties of gallium-doped ZnO (GZO) films. The co-doped films were grown on MgAl2O4 spinel substrates using a low-temperature solution-phase method known as hydrothermal synthesis. Gallium with indium co-doped ZnO (GIZO) films displayed a dramatic improvement in surface morphology as compared with the Ga-doped ZnO (GZO) films due to the compensation effect of gallium and indium doping which reduced the lattice strain. The 0.0033M gallium with 3.3 × 10-4M indium co-doped film exhibited an electron concentration of 3.14 × 1020 cm-3 and resistivity of 7.4 × 10-4 Ω cm which were both enhancements of 1.5 times over the GZO film. These films were comparable to the films fabricated by more expensive and complicated vapour-phase methods. The figure of merit for this film was determined to be 1.63 × 10-2 sq/Ω which was very close to the indium tin oxide conducting films currently used commercially. Finally, the GIZO film was hydrothermally grown on a p-GaN film to form an n-ZnO/p-GaN heterojunction light-emitting diode (LED). This LED showed diode I-V characteristics and exhibited strong cool-white light emission which signified the prospect of using GIZO as an effective and low-cost n-type layer in LEDs.

  11. Fabricating superconducting interfaces between artificially grown LaAlO3 and SrTiO3 thin films

    Directory of Open Access Journals (Sweden)

    Danfeng Li

    2014-01-01

    Full Text Available Realization of a fully metallic two-dimensional electron gas (2DEG at the interface between artificially grown LaAlO3 and SrTiO3 thin films has been an exciting challenge. Here we present for the first time the successful realization of a superconducting 2DEG at interfaces between artificially grown LaAlO3 and SrTiO3 thin films. Our results highlight the importance of two factors—the growth temperature and the SrTiO3 termination. We use local friction force microscopy and transport measurements to determine that in normal growth conditions the absence of a robust metallic state at low temperature in the artificially grown LaAlO3/SrTiO3 interface is due to the nanoscale SrO segregation occurring on the SrTiO3 film surface during the growth and the associated defects in the SrTiO3 film. By adopting an extremely high SrTiO3 growth temperature, we demonstrate a way to realize metallic, down to the lowest temperature, and superconducting 2DEG at interfaces between LaAlO3 layers and artificially grown SrTiO3 thin films. This study paves the way to the realization of functional LaAlO3/SrTiO3 superlattices and/or artificial LaAlO3/SrTiO3 interfaces on other substrates.

  12. Ultraviolet photodetectors based on aluminum gallium nitride films grown by molecular beam epitaxy

    Science.gov (United States)

    Misra, Mira

    2000-10-01

    GaN-AlN alloys are an important class of materials for ultraviolet photodetectors. The focus of this work was to develop photoconducting and photovoltaic detectors based on AlxGa1-xN films, grown by molecular beam epitaxy. GaN photoconducting detectors were fabricated and characterized. Mobility-lifetime products of the films were determined from measurement of photoconductive gain. They varied from 10-2cm2/V to 10 -7cm2/V as resistivity changed from 10 2W-cm to 107W-cm. Spectral response showed a sharp transition at 365nm and three orders of magnitude visible light rejection. Semi-insulating films exhibited fast response time of 20ns. Dynamic range was linear over five orders of magnitude. Low frequency noise spectra were dominated by l/f noise in the 0--100Hz range and by generation-recombination noise in the 100Hz--10KHz range. A trap at DE = 0.32eV was identified from the temperature dependence of the noise spectrum. The noise equivalent power was determined to be 3 x 10-14W/Hz 1/2 at 10KHz for the semi-insulating detectors. Solar-blind UV photoconductive detectors were fabricated using Al xGa1-xN films with Al mole fraction x = 0--0.45. Detectors fabricated on films with Al mole fraction x = 0.45, corresponding to true solar-blind detection, exhibited mobility-lifetime products of 10 -5cm2/V, which is two orders of magnitude higher than that of GaN films of comparable resistivity. These films also exhibited the highest degree of long range atomic ordering. The enhanced photoconductive gain is accounted for by a model, which considers band offsets between the ordered and random domains in the partially ordered alloys, causing spatial separation of photo-carriers and consequently, long recombination lifetimes. Schottky barrier photovoltaic detectors (n-GaN/Ni-Pt), with a mesa-etched vertical geometry, were fabricated. These photodiodes exhibit a responsivity of 0.18A/W at 325nm and NEP of 1.3 x 10-9W/Hz 1/2 at 1KHz. Doping concentrations and barrier heights were

  13. Optical characterization of InAs film grown on SnO2 substrate by the electrodeposition technique

    Science.gov (United States)

    Lajnef, M.; Ezzaouia, H.; Chtourou, R.

    2008-06-01

    Indium arsenide films have been grown by an electrodeposition process at low temperature on a tin oxide (SnO2) substrate. X-ray diffraction studies showed that the as-grown films are poorly crystallized and heat treatment improved the crystallinity of InAs films. Atomic force microscopic measurements revealed that the InAs film surface is formed by particles for which the grain size depends on the electrolysis parameters; we have found that the grain size increases with the electrolysis current density. Absorption measurements show that the band gap energy red-shifts with increasing particle size. This result can be interpreted as a consequence of the quantum confinement effect on the carriers in the nanocrystallites.

  14. Optical characterization of InAs film grown on SnO{sub 2} substrate by the electrodeposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Lajnef, M; Ezzaouia, H; Chtourou, R [Laboratoire de Photovoltaique et Semiconducteurs et de Nanostructure, Centre de Recherche et de Technologie de l' Energie, BP. 95, Hammam-Lif 2050 (Tunisia)], E-mail: Mohamed.Lajnef@yahoo.fr

    2008-06-21

    Indium arsenide films have been grown by an electrodeposition process at low temperature on a tin oxide (SnO{sub 2}) substrate. X-ray diffraction studies showed that the as-grown films are poorly crystallized and heat treatment improved the crystallinity of InAs films. Atomic force microscopic measurements revealed that the InAs film surface is formed by particles for which the grain size depends on the electrolysis parameters; we have found that the grain size increases with the electrolysis current density. Absorption measurements show that the band gap energy red-shifts with increasing particle size. This result can be interpreted as a consequence of the quantum confinement effect on the carriers in the nanocrystallites.

  15. Thermal activation of nitrogen acceptors in ZnO thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Dangbegnon, J.K.; Talla, K.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth (South Africa)

    2010-06-15

    Nitrogen doping in ZnO is inhibited by spontaneous formation of compensating defects. Perfect control of the nitrogen doping concentration is required, since a high concentration of nitrogen could induce the formation of donor defects involving nitrogen. In this work, the effect of post-growth annealing in oxygen ambient on ZnO thin films grown by Metalorganic Chemical Vapor Deposition, using NO as both oxidant and nitrogen dopant, is studied. After annealing at 700 C and above, low-temperature photoluminescence shows the appearance of a transition at {proportional_to}3.23 eV which is interpreted as pair emission involving a nitrogen acceptor. A second transition at {proportional_to}3.15 eV is also discussed. This work suggests annealing as a potential means for p-type doping using nitrogen (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. TEM characterization of organic nanocrystals grown in sol-gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Monnier, Virginie; Bacia, Maria [CNRS and Universite Joseph Fourier, Institut Neel (France); Putaux, Jean-Luc [ICMG-CNRS, Centre de Recherches sur les Macromolecules Vegetales (France); Ibanez, Alain [CNRS and Universite Joseph Fourier, Institut Neel (France)], E-mail: alain.ibanez@grenoble.cnrs.fr

    2008-01-15

    The tetracene molecule (2,3-benzanthracene, C{sub 8}H{sub 12}) was used to synthesize nanocrystals grown in sol-gel thin films, ranging from 10 to 100 nm of diameter. This confined nucleation and growth was compared to microcrystallizations of the same molecule in free solution. Transmission electron microscopy (TEM) was used to characterize these two kinds of tetracene crystals. The observation was performed under low-dose illumination to avoid amorphization of the samples during electron irradiation. Spatial confinement and size distribution of micro- and nanocrystals were compared. Using electron microdiffraction and diffraction patterns simulations, we showed that free microcrystals and nanocrystals confined in gel glasses exhibit the same triclinic P-bar 1 structure. In addition, time-resolved spectroscopy was used to record fluorescence decays, showing a monoexponential fluorescence decay for nanocrystals while microcrystals exhibit a multiexponential decay. The simple signature of nanocrystals luminescence is promising for the future development of chemical or biological sensors.

  17. Zinc sulfide and terbium-doped zinc sulfide films grown by traveling wave reactor atomic layer epitaxy

    CERN Document Server

    Yun, S J; Nam, K S

    1998-01-01

    Zinc sulfide (ZnS) and terbium-doped ZnS (ZnS:Tb) thin films were grown by traveling wave reactor atomic layer epitaxy (ALE). In the present work, ZnCl sub 2 , H sub 2 S, and tris (2,2,6,6-tetramethyl-3,5-heptandionato) terbium (Tb(tmhd) sub 3) were used as the precursors. The dependence of crystallinity and Cl content of ZnS films was investigated on the growth temperature. ZnS and ZnS:Tb films grown at temperatures ranging from 400 to 500 .deg. C showed a hexagonal-2H crystalline structure. The crystallinity of ZnS film was greatly enhanced as the temperature increased. At growth temperatures higher than 450.deg.C, the films showed preferred orientation with mainly (002) diffraction peak. The Cl content decreased from approximately 9 to 1 at.% with the increase in growth temperature from 400 to 500 .deg. C. The segregation of Cl near the surface region and the incorporation of O from Tb(tmhd) sub 3 during ALE process were also observed using Auger electron spectroscopy. The ALE-grown ZnS and ZnS:Tb films re...

  18. Magnetic and magneto-transport studies of MBE grown Cr2Te3 thin films with perpendicular magnetic anisotropy

    Science.gov (United States)

    Roy, Anupam; Guchhait, Samaresh; Dey, Rik; Pramanik, Tanmoy; Hsieh, Cheng-Chih; Rai, Amritesh; Banerjee, Sanjay

    2015-03-01

    Cr2Te3 is one of the very intriguing compounds in chromium chalcogenides family because of its unusual magnetic and magneto-transport properties. Here we have presented studies of molecular beam epitaxy (MBE) grown (001)-oriented Cr2Te3 thin films on Al2O3(0001) and Si(111)-(7 ×7) surfaces. Reflection high energy electron diffraction (RHEED), scanning tunneling microscopy (STM), vibrating sample magnetometry (VSM) and other physical property measurements are used to investigate the structure, morphology, magnetic and magneto-transport properties of as-grown films. Sharp streaks in RHEED patterns imply smooth film growth on both the substrates. STM studies show hexagonal arrangements of surface atoms and measured lattice parameters agree well with the bulk crystal structures. Magnetic studies confirm the film to be ferromagnetic having a Curie temperature of about 180 K and a spin glass-like behavior is observed below 35 K. The grown films are metallic and show perpendicular magnetic anisotropy (PMA). Magneto-transport measurements reveal that the film possesses a magnetic easy axis perpendicular to the surface and this may be very useful for spintronics applications. This work is funded by NRI-SWAN.

  19. Enhanced ferromagnetic response in ZnO:Mn thin films by tailoring composition and defect concentration

    Science.gov (United States)

    Ilyas, Usman; Tan, T. L.; Lee, P.; Ramanujan, R. V.; Li, Fengji; Zhang, Sam; Chen, R.; Sun, H. D.; Rawat, R. S.

    2013-10-01

    The presence of structural defects degrade the crystalline quality of ZnO:Mn thin films and affects the magneto-optical properties of ZnO:Mn thin films. The donor defects in ZnO, which are known to be the source of n-type conductivity in ZnO host matrix, play an important role in limiting the ferromagnetism to lower temperatures. A systematic study of structural, optical and magnetic properties was carried out with the primary focus on understanding the relationship between the defect concentration, material composition and ferromagnetic properties. Single phase ZnO:Mn thin films with wurtzite structure were grown under ambient argon-oxygen admixture to investigate the effect of stoichiometry and interstitial oxygen on magnetic properties. A consistent increase in crystallinity of ZnO:Mn thin films (without precipitation of Mn) with increasing argon-oxygen admixture gas pressure was observed. Extended near band edge (NBE) emission spectra with marked decrease in photoluminescence (PL) ratio in optical characterization revealed improved optical quality of ZnO:Mn thin films. Magnetic measurements revealed enhanced room temperature ferromagnetism (RTFM) in sample grown at optimum argon-oxygen ambient pressure. The enhancement was directly related to maximal core level X-ray photoelectron spectroscopic peak of stoichiometric ZnO which, in turn, favors strong hybridization of Mn in the ZnO host matrix.

  20. Structure and composition of Zn(x)Cd(1-xS) films synthesized through chemical bath deposition.

    Science.gov (United States)

    Tosun, B Selin; Pettit, Chelsea; Campbell, Stephen A; Aydil, Eray S

    2012-07-25

    Zinc cadmium sulfide (ZnxCd1-xS) thin films grown through chemical bath deposition are used in chalcopyrite solar cells as the buffer layer between the n-type zinc oxide and the p-type light absorbing chalcopyrite film. To optimize energetic band alignment and optical absorption, advanced solar cell architectures require the ability to manipulate x as a function of distance from the absorber-ZnCdS interface. Herein, we investigate the fundamental factors that govern the evolution of the composition as a function of depth in the film. By changing the initial concentrations of Zn and Cd salts in the bath, the entire range of overall compositions ranging from primarily cubic ZnS to primarily hexagonal CdS could be deposited. However, films are inhomogeneous and x varies significantly as function of distance from the film-substrate interface. Films with high overall Zn concentration (x > 0.5) exhibit a Cd-rich layer near the film-substrate interface because Cd is more reactive than Zn. This layer is typically beneath a nearly pure ZnS film that forms after the Cd-rich layers are deposited and Cd is depleted in the bath. In films with high overall Cd concentration (x < 0.5) the Zn concentration rises towards the film's surface. Fortunately, these gradients are favorable for solar cells based on low band gap chalcopyrite films.

  1. Study of the gradual interface between hydroxyapatite thin films PLD grown onto Ti-controlled sublayers

    Energy Technology Data Exchange (ETDEWEB)

    Grigorescu, S. [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg (France); National Institute for Laser, Plasma and Radiation Physics, Laser Department, PO Box MG-36, 077125 Bucharest (Romania)], E-mail: sorin.grigorescu@inflpr.ro; Carrado, A.; Ulhaq, C.; Faerber, J. [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg (France); Ristoscu, C.; Dorcioman, G.; Axente, E. [National Institute for Laser, Plasma and Radiation Physics, Laser Department, PO Box MG-36, 077125 Bucharest (Romania); Werckmann, J. [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg (France); Mihailescu, I.N. [National Institute for Laser, Plasma and Radiation Physics, Laser Department, PO Box MG-36, 077125 Bucharest (Romania)

    2007-12-15

    Hydroxyapatite thin films were grown on layered structures by Pulsed Laser Deposition with the goal of investigating the interface of the ceramic film with the substrate. The latter consisted of Si/TiN/Ti sandwich structures. This multilayer substrate was also prepared by laser ablation earlier in the same experimental session. This particular type of structure was chosen in order to induce the in situ growth of hydroxyapatite directly onto freshly deposited Ti. We tried this way to avoid previous direct Ti exposure to air, hence its oxidation. The subsequent depositions of multilayers were performed with the aid of a carousel multi-target system mounted inside the irradiation chamber. This allowed for selecting in order the respective TiN, Ti and HA targets without opening the chamber between individual depositions. X-ray diffractometry, transmission electron microscopy and selected area electron diffractometry studies revealed the formation at the interface of a transition complex phase, 2 to 25 nm thick, consisting of a mixture of TiO{sub 2} and CaP phase. The specific growth of TiN and Ti phases was also investigated.

  2. Effect of growth temperature on defects in epitaxial GaN film grown by plasma assisted molecular beam epitaxy

    Directory of Open Access Journals (Sweden)

    S. S. Kushvaha

    2014-02-01

    Full Text Available We report the effect of growth temperature on defect states of GaN epitaxial layers grown on 3.5 μm thick GaN epi-layer on sapphire (0001 substrates using plasma assisted molecular beam epitaxy. The GaN samples grown at three different substrate temperatures at 730, 740 and 750 °C were characterized using atomic force microscopy and photoluminescence spectroscopy. The atomic force microscopy images of these samples show the presence of small surface and large hexagonal pits on the GaN film surfaces. The surface defect density of high temperature grown sample is smaller (4.0 × 108 cm−2 at 750 °C than that of the low temperature grown sample (1.1 × 109 cm−2 at 730 °C. A correlation between growth temperature and concentration of deep centre defect states from photoluminescence spectra is also presented. The GaN film grown at 750 °C exhibits the lowest defect concentration which confirms that the growth temperature strongly influences the surface morphology and affects the optical properties of the GaN epitaxial films.

  3. Effect of growth temperature on defects in epitaxial GaN film grown by plasma assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kushvaha, S. S., E-mail: kushvahas@nplindia.org; Pal, P.; Shukla, A. K.; Joshi, Amish G.; Gupta, Govind; Kumar, M.; Singh, S.; Gupta, Bipin K.; Haranath, D. [CSIR- National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi, India 110012 (India)

    2014-02-15

    We report the effect of growth temperature on defect states of GaN epitaxial layers grown on 3.5 μm thick GaN epi-layer on sapphire (0001) substrates using plasma assisted molecular beam epitaxy. The GaN samples grown at three different substrate temperatures at 730, 740 and 750 °C were characterized using atomic force microscopy and photoluminescence spectroscopy. The atomic force microscopy images of these samples show the presence of small surface and large hexagonal pits on the GaN film surfaces. The surface defect density of high temperature grown sample is smaller (4.0 × 10{sup 8} cm{sup −2} at 750 °C) than that of the low temperature grown sample (1.1 × 10{sup 9} cm{sup −2} at 730 °C). A correlation between growth temperature and concentration of deep centre defect states from photoluminescence spectra is also presented. The GaN film grown at 750 °C exhibits the lowest defect concentration which confirms that the growth temperature strongly influences the surface morphology and affects the optical properties of the GaN epitaxial films.

  4. Ferrocene carboxaldehyde thin films grown by matrix-assisted pulsed laser evaporation for non linear optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Constantinescu, Catalin [INFLPR—National Institute for Laser, Plasma and Radiation Physics, PPAM/Lasers Department, 409 Atomistilor boulevard, Magurele, RO-077125 Bucharest (Romania); Matei, Andreea, E-mail: andreeapurice@nipne.ro [INFLPR—National Institute for Laser, Plasma and Radiation Physics, PPAM/Lasers Department, 409 Atomistilor boulevard, Magurele, RO-077125 Bucharest (Romania); Ion, Valentin; Mitu, Bogdana [INFLPR—National Institute for Laser, Plasma and Radiation Physics, PPAM/Lasers Department, 409 Atomistilor boulevard, Magurele, RO-077125 Bucharest (Romania); Ionita, Iulian [INFLPR—National Institute for Laser, Plasma and Radiation Physics, PPAM/Lasers Department, 409 Atomistilor boulevard, Magurele, RO-077125 Bucharest (Romania); UB—University of Bucharest, Faculty of Physics, 405 Atomistilor Street, Magurele, RO-077125 Bucharest (Romania); Dinescu, Maria; Luculescu, Catalin R. [INFLPR—National Institute for Laser, Plasma and Radiation Physics, PPAM/Lasers Department, 409 Atomistilor boulevard, Magurele, RO-077125 Bucharest (Romania); Vasiliu, Cristina [INOE2000—National Institute for Research and Development in Optoelectronics, 1 Atomistilor Street, Magurele, RO-077125 Bucharest (Romania); Emandi, Ana [INOE2000—National Institute for Research and Development in Optoelectronics, 1 Atomistilor Street, Magurele, RO-077125 Bucharest (Romania); UB—University of Bucharest, Faculty of Chemistry, Department of Inorganic Chemistry, 90–92 Panduri Street, RO-050663 Bucharest (Romania)

    2014-05-01

    Thin films of ferrocene carboxaldehyde, also known as cyclopentadienyl(formylcyclopentadienyl)iron, were grown on silicon and glass substrates by matrix-assisted pulsed laser evaporation technique, using a Nd:YAG device operating at 266 nm (4ω). Spectroscopic-ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy and atomic force microscopy investigations revealed that the films are homogeneous in thickness, with dense morphology and without cracks, low surface roughness (∼11 nm), and no significant chemical damage. Second harmonic generation capabilities of the thin films were evidenced by using a femtosecond Ti:sapphire laser.

  5. Biomolecular urease thin films grown by laser techniques for blood diagnostic applications

    Energy Technology Data Exchange (ETDEWEB)

    Gyoergy, E., E-mail: eniko.gyorgy@inflpr.ro [Consejo Superior de Investigaciones Cientificas, Institut de Ciencia de Materials de Barcelona and Centre d' Investigacions en Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Spain); National Institute for Lasers, Plasma and Radiations Physics, P. O. Box MG 36, 77125 Bucharest (Romania); Sima, F.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiations Physics, P. O. Box MG 36, 77125 Bucharest (Romania); Smausz, T. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Hopp, B. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Predoi, D. [National Institute for Physics of Materials, P.O. Box MG 07, Bucharest, Magurele (Romania); Sima, L.E.; Petrescu, S.M. [Institute of Biochemistry, Romanian Academy, Splaiul Independentei 296, 060031 Bucharest (Romania)

    2010-05-10

    Matrix assisted pulsed laser evaporation (MAPLE) was used for growing urease thin films designed for bio-sensor applications in clinical diagnostics. The targets exposed to laser radiation were made from a frozen composite manufactured by dissolving biomaterials in distilled water. We used a UV KrF* ({lambda} = 248 nm, {tau}{sub FWHM} {approx_equal} 30 ns, {nu} = 10 Hz) excimer source for multipulse laser irradiation of the frozen targets cooled with Peltier elements. The laser source was operated at an incident fluence of 0.4 J/cm{sup 2}. Urease activity and kinetics were assayed by the Worthington method that monitors urea hydrolysis by coupling ammonia production to a glutamate dehydrogenase reaction. A decrease in absorbance was measured at 340 nm and correlated with the enzymatic activity of urease. We show that the urease films obtained by MAPLE techniques remain active up to three months after deposition.

  6. Coassembly of gold nanoparticles and cellulose nanocrystals in composite films.

    Science.gov (United States)

    Lukach, Ariella; Thérien-Aubin, Héloïse; Querejeta-Fernández, Ana; Pitch, Natalie; Chauve, Grégory; Méthot, Myriam; Bouchard, Jean; Kumacheva, Eugenia

    2015-05-12

    Coassembly of nanoparticles with different size-, shape-, and composition-dependent properties is a promising approach to the design and fabrication of functional materials and devices. This paper reports the results of a detailed investigation of the formation and properties of free-stranding composite films formed by the coassembly of cellulose nanocrystals and shape-isotropic plasmonic gold nanoparticles. The effect of gold nanoparticle size, surface charge, and concentration on the structural and optical properties of the composite films has been studied. The composite films retained photonic crystal and chiroptical activity properties. The size and surface charge of gold nanoparticles had a minor effect on the structure and properties of the composite films, while the concentration of gold nanoparticles in the composite material played a more significant role and can be used to fine-tune the optical properties of materials derived from cellulose nanocrystals. These findings significantly broaden the range of nanoparticles that can be used for producing nanocomposite materials based on cellulose nanocrystals. The simplicity of film preparation, the abundance of cellulose nanocrystals, and the robust, free-standing nature of the composite films offer highly advantageous features and pave the way for the generation of functional materials with coupled optical properties.

  7. Surface structure and electrochemical properties of platinum films grown on SrTiO3(100) substrates

    Science.gov (United States)

    Kasai, Masahiro; Dohi, Hideyuki

    2017-12-01

    We fabricated Pt films on SrTiO3 (STO)(100) using a DC-magnetron sputtering method to investigate the preferred orientation, surface structure, and electrochemical property. A film grown at 400 °C showed the two-dimensional polycrystalline features of Pt(111). Reflection high-energy electron diffraction (RHEED) showed diffraction patterns independent of the in-plane incident angle of the film. Films grown at 600 and 700 °C exhibited a preferred orientation of Pt(100) and (110). The films exhibited the morphology of faceted islands with roughness of several tens of nm, which consisted of two kinds of domains, namely a domain with preferred orientation of (100) and one with (110). The (100) and (110) domains had 45-degree twin boundaries, which were observed as V-shaped streaks by RHEED. The (100) domain was aligned in orientation of [011]Pt//[010]STO, which suggests that the binding strength of the (110) plane at the interface was larger than that of the (100). With a further increase in the growth temperature up to 750 °C, the film primarily showed a preferred orientation of (100) with an in-plane orientation of [010]Pt//[010]STO. The film also showed an island structure; however, atomic force microscopy revealed that the top was atomically flat.

  8. Optical properties of aluminum nitride thin films grown by direct-current magnetron sputtering close to epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, A. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Soltani, A., E-mail: ali.soltani@iemn.univ-lille1.fr [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Abdallah, B. [Department of Materials Physics, Atomic Energy Commission of Syria, Damascus, P.O. Box 6091 (Syrian Arab Republic); Charrier, J. [Fonctions Optiques pour les Technologies de l' informatiON (FOTON), UMR CNRS 6082, 6, rue de Kerampont CS 80518, 22305 Lannion Cedex (France); Deresmes, D. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Jouan, P.-Y.; Djouadi, M.A. [Institut des Matériaux Jean Rouxel – IMN, UMR CNRS 6502, 2, rue de la Houssinère BP 32229, 44322 Nantes (France); Dogheche, E.; De Jaeger, J.-C. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France)

    2013-05-01

    Low-temperature Aluminum Nitride (AlN) thin films with a thickness of 3 μm were deposited by Direct-Current magnetron sputtering on sapphire substrate. They present optical properties similar to those of epitaxially grown films. Different characterization methods such as X-Ray Diffraction, Transmission Electron Microscopy and Atomic Force Microscopy were used to determine the structural properties of the films such as its roughness and crystallinity. Newton interferometer was used for stress measurement of the films. Non-destructive prism-coupling technique was used to determine refractive index and thickness homogeneity by a mapping on the whole sample area. Results show that AlN films grown on AlGaN layer have a high crystallinity close to epitaxial films, associated to a low intrinsic stress for low thickness. These results highlight that it is possible to grow thick sample with microstructure and optical properties close to epitaxy, even on a large surface. - Highlights: ► Aluminum Nitride sputtering technique with a low temperature growth process ► Epitaxial quality of two microns sputtered Aluminum Nitride film ► Optics as a non-destructive accurate tool for acoustic wave investigation.

  9. RBS/Channeling study of Er doped GaN films grown by MBE on Si(1 1 1) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, K.; Vianden, R.; Birkhahn, R.; Steckl, A.J.; Silva, M.F. da; Soares, J.C.; Alves, E. E-mail: ealves@itn1.itn.pt

    2000-03-01

    The influence of the Ga cell temperature on the quality of GaN films grown by MBE on p-Si(1 1 1) substrates was studied for cell temperatures (T{sub Ga}) in the range from 865 deg. C to 922 deg. C using the RBS/Channeling technique. The films were in situ doped during growth with Er at a constant cell temperature. The films show a strong dependence of the crystalline quality on the Ga cell temperature with the best films grown at T{sub Ga}=915 deg C. For temperatures T{sub Ga} below 880 deg. C the films showed no channeling effect. The thickness increases linearly with the temperature suggesting that changes in the Ga flux influence the growth process. The decrease of the Ga flux allows the incorporation of higher Er concentrations in the films. The data showed that a maximum value of about 0.35 at% was reached under the chosen growth conditions. The Er ions occupy mainly the Ga sublattice in the films with single crystalline quality. A comparison of the angular scans through the <0 0 0 1> and the <1 0 1 =macron 1> axes with Monte Carlo simulations leads to the conclusion that a majority ({approx}90%) of the Er ions occupies Ga sites.

  10. Impact of deposition temperature on the properties of SnS thin films grown over silicon substrate—comparative study of structural and optical properties with films grown on glass substrates

    Science.gov (United States)

    Assili, Kawther; Alouani, Khaled; Vilanova, Xavier

    2017-11-01

    Tin sulfide (SnS) thin films were chemically deposited over silicon substrate in a temperature range of 250 °C–400 °C. The effects of deposition temperature on the structural, morphological and optical properties of the films were evaluated. All films present an orthorhombic SnS structure with a preferred orientation along (040). High absorption coefficients (in the range of 105 cm‑1) were found for all obtained films with an increase in α value when deposition temperature decreases. Furthermore, the effects of substrate type were investigated based on comparison between the present results and those obtained for SnS films grown under the same deposition conditions but over glass substrate. The results suggest that the formation of SnS films onto glass substrate is faster than onto silicon substrate. It is found that the substrate nature affects the orientation growth of the films and that SnS films deposited onto Si present more defects than those deposited onto glass substrate. The optical transmittance is also restricted by the substrate type, mostly below 1000 nm. The obtained results for SnS films onto silicon suggest their promising integration within optoelectronic devices.

  11. Microstructures of InN film on 4H-SiC (0001) substrate grown by RF-MBE

    Science.gov (United States)

    Jantawongrit, P.; Sanorpim, S.; Yaguchi, H.; Orihara, M.; Limsuwan, P.

    2015-08-01

    InN film was grown on 4H-SiC (0001) substrate by RF plasma-assisted molecular beam epitaxy (RF-MBE). Prior to the growth of InN film, an InN buffer layer with a thickness of ∼5.5 nm was grown on the substrate. Surface morphology, microstructure and structural quality of InN film were investigated. Micro-structural defects, such as stacking faults and anti-phase domain in InN film were carefully investigated using transmission electron microscopy (TEM). The results show that a high density of line contrasts, parallel to the growth direction (c-axis), was clearly observed in the grown InN film. Dark field TEM images recorded with diffraction vectors g=11\\bar{2}0 and g = 0002 revealed that such line contrasts evolved from a coalescence of the adjacent misoriented islands during the initial stage of the InN nucleation on the substrate surface. This InN nucleation also led to a generation of anti-phase domains. Project supported by the Thailand Center of Excellence in Physics (ThEP) and the King Mongkut's University of Technology Thonburi under The National Research University Project. One of the authors (S. Sanorpim) was supported by the National Research Council of Thailand (NRCT) and the Thai Government Stimulus Package 2 (TKK2555), under the Project for Establishment of Comprehensive Center for Innovative Food, Health Products and Agriculture.

  12. Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

    Science.gov (United States)

    Feng, Guo-Hua; Lee, Kuan-Yi

    2017-12-01

    This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal-oxide-semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air.

  13. Self-organized single crystal mixed magnetite/cobalt ferrite films grown by infrared pulsed-laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Figuera, Juan de la, E-mail: juan.delafiguera@iqfr.csic.es [Instituto de Química Física “Rocasolano”, CSIC, Madrid E-28006 (Spain); Quesada, Adrián [Instituto de Cerámica y Vidrio, CSIC, Madrid E-28049 (Spain); Martín-García, Laura; Sanz, Mikel; Oujja, Mohamed; Rebollar, Esther; Castillejo, Marta [Instituto de Química Física “Rocasolano”, CSIC, Madrid E-28006 (Spain); Prieto, Pilar; Muñoz-Martín, Ángel [Universidad Autónoma de Madrid, E-28049 (Spain); Aballe, Lucía [Alba Synchrotron Light Facility, CELLS, Barcelona (Spain); Marco, José F. [Instituto de Química Física “Rocasolano”, CSIC, Madrid E-28006 (Spain)

    2015-12-30

    Highlights: • Infrared pulsed deposition is used to grow single crystal mixed magnetite-cobalt ferrite films. • Distinct topography with two mound types on the surface of the film. • Suggested origin of segregation into two phases is oxygen deficiency during growth. • Mössbauer is required to quantify the two components. - Abstract: We have grown mixed magnetite/cobalt ferrite epitaxial films on SrTiO{sub 3} by infrared pulsed-laser deposition. Diffraction experiments indicate epitaxial growth with a relaxed lattice spacing. The films are flat with two distinct island types: nanometric rectangular mounds in two perpendicular orientations, and larger square islands, attributed to the two main components of the film as determined by Mössbauer spectroscopy. The origin of the segregation is suggested to be the oxygen-deficiency during growth.

  14. Microwave-assisted hydrothermally grown epitaxial ZnO films on MgAl2O4 substrate

    Science.gov (United States)

    Liew, Laura-Lynn; Le, Hong Quang; Goh, Gregory K. L.

    2012-05-01

    In this report, epitaxial ZnO films were grown on MgAl2O4 single crystal substrates using Microwave Assisted Hydrothermal (MAH) method with microwave radiation heating (2.45 GHz) at 90 °C in a short time (within 15 min). Scanning electron microscopy confirms that these films possess smooth surface morphology with fully coalesced grains. In addition, photoluminescence (PL) measurements exhibit strong ultraviolet emission at room temperature, indicating potential applications for short-wave light-emitting photonic devices. The PL properties were improved by a thermal annealing process without generating structural defects. Hall measurements after thermal treatment show the carrier concentration to be of the order of 1019 cm-3 which is comparable to those grown by conventional solution methods. The MAH method will offer a rapid route to synthesize epitaxial ZnO films with good optical and electrical properties for various applications.

  15. Atom-Thick Interlayer Made of CVD-Grown Graphene Film on Separator for Advanced Lithium-Sulfur Batteries.

    Science.gov (United States)

    Du, Zhenzhen; Guo, Chengkun; Wang, Linjun; Hu, Ajuan; Jin, Song; Zhang, Taiming; Jin, Hongchang; Qi, Zhikai; Xin, Sen; Kong, Xianghua; Guo, Yu-Guo; Ji, Hengxing; Wan, Li-Jun

    2017-12-20

    Lithium-sulfur batteries are widely seen as a promising next-generation energy-storage system owing to their ultrahigh energy density. Although extensive research efforts have tackled poor cycling performance and self-discharge, battery stability has been improved at the expense of energy density. We have developed an interlayer consisting of two-layer chemical vapor deposition (CVD)-grown graphene supported by a conventional polypropylene (PP) separator. Unlike interlayers made of discrete nano-/microstructures that increase the thickness and weight of the separator, the CVD-graphene is an intact film with an area of 5 × 60 cm2 and has a thickness of ∼0.6 nm and areal density of ∼0.15 μg cm-2, which are negligible to those of the PP separator. The CVD-graphene on PP separator is the thinnest and lightest interlayer to date and is able to suppress the shuttling of polysulfides and enhance the utilization of sulfur, leading to concurrently improved specific capacity, rate capability, and cycle stability and suppressed self-discharge when assembled with cathodes consisting of different sulfur/carbon composites and electrolytes either with or without LiNO3 additive.

  16. Phyllosphere microbiota composition and microbial community transplantation on lettuce plants grown indoors.

    Science.gov (United States)

    Williams, Thomas R; Marco, Maria L

    2014-08-12

    The aerial surfaces of plants, or phyllosphere, are microbial habitats important to plant and human health. In order to accurately investigate microbial interactions in the phyllosphere under laboratory conditions, the composition of the phyllosphere microbiota should be representative of the diversity of microorganisms residing on plants in nature. We found that Romaine lettuce grown in the laboratory contained 10- to 100-fold lower numbers of bacteria than age-matched, field-grown lettuce. The bacterial diversity on laboratory-grown plants was also significantly lower and contained relatively higher proportions of Betaproteobacteria as opposed to the Gammaproteobacteria-enriched communities on field lettuce. Incubation of field-grown Romaine lettuce plants in environmental growth chambers for 2 weeks resulted in bacterial cell densities and taxa similar to those on plants in the field but with less diverse bacterial populations overall. In comparison, the inoculation of laboratory-grown Romaine lettuce plants with either freshly collected or cryopreserved microorganisms recovered from field lettuce resulted in the development of a field-like microbiota on the lettuce within 2 days of application. The survival of an inoculated strain of Escherichia coli O157:H7 was unchanged by microbial community transfer; however, the inoculation of E. coli O157:H7 onto those plants resulted in significant shifts in the abundance of certain taxa. This finding was strictly dependent on the presence of a field-associated as opposed to a laboratory-associated microbiota on the plants. Phyllosphere microbiota transplantation in the laboratory will be useful for elucidating microbial interactions on plants that are important to agriculture and microbial food safety. The phyllosphere is a habitat for a variety of microorganisms, including bacteria with significant relevance to plant and human health. Some indigenous epiphytic bacteria might affect the persistence of human food

  17. ALD grown nanostructured ZnO thin films: Effect of substrate temperature on thickness and energy band gap

    Directory of Open Access Journals (Sweden)

    Javed Iqbal

    2016-10-01

    Full Text Available Nanostructured ZnO thin films with high transparency have been grown on glass substrate by atomic layer deposition at various temperatures ranging from 100 °C to 300 °C. Efforts have been made to observe the effect of substrate temperature on the thickness of the deposited thin films and its consequences on the energy band gap. A remarkably high growth rate of 0.56 nm per cycle at a substrate temperature of 200 °C for ZnO thin films have been achieved. This is the maximum growth rate for ALD deposited ZnO thin films ever reported so far to the best of our knowledge. The studies of field emission scanning electron microscopy and X-ray diffractometry patterns confirm the deposition of uniform and high quality nanosturtured ZnO thin films which have a polycrystalline nature with preferential orientation along (100 plane. The thickness of the films deposited at different substrate temperatures was measured by ellipsometry and surface profiling system while the UV–visible and photoluminescence spectroscopy studies have been used to evaluate the optical properties of the respective thin films. It has been observed that the thickness of the thin film depends on the substrate temperatures which ultimately affect the optical and structural parameters of the thin films.

  18. Electrical and optical properties of Y-doped indium zinc oxide films grown by RF magnetron sputtering.

    Science.gov (United States)

    Lee, Young-Jun; Kim, Joo-Hyung; Oh, Byeong-Yun; Kim, Kwang-Young

    2013-09-01

    Y2O3-doped IZO (YIZO) films was investigated in order to control the carrier concentration of semiconducting IZO layer. Stoichiometric thin YIZO films were deposited on glass substrates by RF magnetron sputtering method using indium zinc oxide (IZO) including 50 wt.% ZnO and Y2O3 targets. During the deposition of YIZO films, the working pressure was fixed at 0.17 Pa and the deposition temperature was kept at room temperature while the oxygen partial pressure (P(O2)) was changed to find the optimal film condition. In order to check the PO2 effect on structural, electrical and optical properties of the grown YIZO layer on glass, X-ray diffraction (XRD) was employed to analyze the structure of YIZO films and the electrical properties were characterized by Hall measurements using the Van der Pauw geometry at room temperature. From the measured XRD patterns, exhibiting crystalline peak of the YIZO film deposited under PO2 condition is revealed while amorphous phase structure is only observed from the YIZO film deposited under pure Ar gas condition. As the O2 contents in gas increase, the resistivity of YIZO film also drastically increases, whereas the carrier concentration of the YIZO films sharply decreases with mobility.

  19. Nucleation and growth dynamics of MBE-grown topological insulator Bi{sub 2}Te{sub 3} films on Si (111)

    Energy Technology Data Exchange (ETDEWEB)

    Borisova, Svetlana; Krumrain, Julian; Mussler, Gregor; Grützmacher, Detlev [Peter Grünberg Institut - 9, Forschungszentrum Jülich, 52425 Jülich, Germany and JARA - Fundamentals of Future Information Technologies (Germany); Luysberg, Martina [Peter Grünberg Institut - 5 and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425 Jülich (Germany)

    2013-12-04

    Topological insulator Bi{sub 2}Te{sub 3} films have been grown by molecular beam epitaxy on Si (111) substrates. The structural properties of the ultra-thin films and their evolution in morphology during the growth have been investigated. The growth starts by a nucleation of separate islands and subsequently turns into a layer-by-layer growth mode. Despite this, the grown film is found to be single crystalline and fully relaxed from the first atomic layer.

  20. Enhanced ferromagnetic response in ZnO:Mn thin films by tailoring composition and defect concentration

    Energy Technology Data Exchange (ETDEWEB)

    Ilyas, Usman [NSSE, NIE, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Department of Physics, University of Engineering and Technology, Lahore 54890 (Pakistan); Tan, T.L.; Lee, P. [NSSE, NIE, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Ramanujan, R.V. [School of Material Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Li, Fengji; Zhang, Sam [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Chen, R.; Sun, H.D. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Rawat, R.S., E-mail: rajdeep.rawat@nie.edu.sg [NSSE, NIE, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

    2013-10-15

    The presence of structural defects degrade the crystalline quality of ZnO:Mn thin films and affects the magneto-optical properties of ZnO:Mn thin films. The donor defects in ZnO, which are known to be the source of n-type conductivity in ZnO host matrix, play an important role in limiting the ferromagnetism to lower temperatures. A systematic study of structural, optical and magnetic properties was carried out with the primary focus on understanding the relationship between the defect concentration, material composition and ferromagnetic properties. Single phase ZnO:Mn thin films with wurtzite structure were grown under ambient argon–oxygen admixture to investigate the effect of stoichiometry and interstitial oxygen on magnetic properties. A consistent increase in crystallinity of ZnO:Mn thin films (without precipitation of Mn) with increasing argon–oxygen admixture gas pressure was observed. Extended near band edge (NBE) emission spectra with marked decrease in photoluminescence (PL) ratio in optical characterization revealed improved optical quality of ZnO:Mn thin films. Magnetic measurements revealed enhanced room temperature ferromagnetism (RTFM) in sample grown at optimum argon–oxygen ambient pressure. The enhancement was directly related to maximal core level X-ray photoelectron spectroscopic peak of stoichiometric ZnO which, in turn, favors strong hybridization of Mn in the ZnO host matrix. - Highlights: • Enhanced ferromagnetism under controlled argon–oxygen ambient pressure of 2 mbar. • Direct correlation between Zn−O bonding and ferromagnetic response in ZnO:Mn samples. • Improved crystallinity of thin films without in-situ or post-deposition annealing. • Reduced PL ratio (DLE/NBE) with improved optical transparency of ZnO:Mn thin films.

  1. Epitaxial CuInSe2 thin films grown by molecular beam epitaxy and migration enhanced epitaxy

    Science.gov (United States)

    Abderrafi, K.; Ribeiro-Andrade, R.; Nicoara, N.; Cerqueira, M. F.; Gonzalez Debs, M.; Limborço, H.; Salomé, P. M. P.; Gonzalez, J. C.; Briones, F.; Garcia, J. M.; Sadewasser, S.

    2017-10-01

    While CuInSe2 chalcopyrite materials are mainly used in their polycrystalline form to prepare thin film solar cells, epitaxial layers have been used for the characterization of defects. Typically, epitaxial layers are grown by metal-organic vapor phase epitaxy or molecular beam epitaxy (MBE). Here we present epitaxial layers grown by migration enhanced epitaxy (MEE) and compare the materials quality to MBE grown layers. CuInSe2 layers were grown on GaAs (0 0 1) substrates by co-evaporation of Cu, In, and Se using substrate temperatures of 450 °C, 530 °C, and 620 °C. The layers were characterized by high resolution X-ray diffraction (HR-XRD), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and atomic force microscopy (AFM). HR-XRD and HR-TEM show a better crystalline quality of the MEE grown layers, and Raman scattering measurements confirm single phase CuInSe2. AFM shows the previously observed faceting of the (0 0 1) surface into {1 1 2} facets with trenches formed along the [1 1 0] direction. The surface of MEE-grown samples appears smoother compared to MBE-grown samples, a similar trend is observed with increasing growth temperature.

  2. Annealing Effect on the Structural and Optical Properties of Sputter-Grown Bismuth Titanium Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    José E. Alfonso

    2014-04-01

    Full Text Available The aim of this work is to assess the evolution of the structural and optical properties of BixTiyOz films grown by rf magnetron sputtering upon post-deposition annealing treatments in order to obtain good quality films with large grain size, low defect density and high refractive index similar to that of single crystals. Films with thickness in the range of 220–250 nm have been successfully grown. After annealing treatment at 600 °C the films show excellent transparency and full crystallization. It is shown that to achieve larger crystallite sizes, up to 17 nm, it is better to carry the annealing under dry air than under oxygen atmosphere, probably because the nucleation rate is reduced. The refractive index of the films is similar under both atmospheres and it is very high (n =2.5 at 589 nm. However it is still slightly lower than that of the single crystal value due to the polycrystalline morphology of the thin films.

  3. Investigation of bonded hydrogen defects in nanocrystalline diamond films grown with nitrogen/methane/hydrogen plasma at high power conditions

    Science.gov (United States)

    Tang, C. J.; Hou, Haihong; Fernandes, A. J. S.; Jiang, X. F.; Pinto, J. L.; Ye, H.

    2017-02-01

    In this work, we investigate the influence of some growth parameters such as high microwave power ranging from 3.0 to 4.0 kW and N2 additive on the incorporation of bonded hydrogen defects in nanocrystalline diamond (NCD) films grown through a small amount of pure N2 addition into conventional 4% CH4/H2 plasma using a 5 kW microwave plasma CVD system. Incorporation form and content of hydrogen point defects in the NCD films produced with pure N2 addition was analyzed by employing Fourier-transform infrared (FTIR) spectroscopy for the first time. A large amount of hydrogen related defects was detected in all the produced NCD films with N2 additive ranging from 29 to 87 μm thick with grain size from 47 nm to 31 nm. Furthermore, a specific new H related sharp absorption peak appears in all the NCD films grown with pure N2/CH4/H2 plasma at high powers and becomes stronger at powers higher than 3.0 kW and is even stronger than the 2920 cm-1 peak, which is commonly found in CVD diamond films. Based on these experimental findings, the role of high power and pure nitrogen addition on the growth of NCD films including hydrogen defect formation is analyzed and discussed.

  4. Annealing Effect on the Structural and Optical Properties of Sputter-Grown Bismuth Titanium Oxide Thin Films

    Science.gov (United States)

    Alfonso, José E.; Olaya, Jhon J.; Bedoya-Hincapié, Claudia M.; Toudert, Johann; Serna, Rosalia

    2014-01-01

    The aim of this work is to assess the evolution of the structural and optical properties of BixTiyOz films grown by rf magnetron sputtering upon post-deposition annealing treatments in order to obtain good quality films with large grain size, low defect density and high refractive index similar to that of single crystals. Films with thickness in the range of 220–250 nm have been successfully grown. After annealing treatment at 600 °C the films show excellent transparency and full crystallization. It is shown that to achieve larger crystallite sizes, up to 17 nm, it is better to carry the annealing under dry air than under oxygen atmosphere, probably because the nucleation rate is reduced. The refractive index of the films is similar under both atmospheres and it is very high (n =2.5 at 589 nm). However it is still slightly lower than that of the single crystal value due to the polycrystalline morphology of the thin films. PMID:28788626

  5. Temperature-controlled transparent-film heater based on silver nanowire-PMMA composite film

    Science.gov (United States)

    He, Xin; Liu, A.'lei; Hu, Xuyang; Song, Mingxia; Duan, Feng; Lan, Qiuming; Xiao, Jundong; Liu, Junyan; Zhang, Mei; Chen, Yeqing; Zeng, Qingguang

    2016-11-01

    We fabricated a high-performance film heater based on a silver nanowire and polymethyl methacrylate (Ag NW-PMMA) composite film, which was synthesized with the assistance of mechanical lamination and an in situ transfer method. The films exhibit excellent conductivity, high figure of merit, and strong adhesion of percolation network to substrate. By controlling NW density, we prepared the films with a transmittance of 44.9-85.0% at 550 nm and a sheet resistance of 0.13-1.40 Ω sq-1. A stable temperature ranging from 130 °C-40 °C was generated at 3.0 V within 10-30 s, indicating that the resulting film heaters show a rapid thermal response, low driving voltage and stable temperature recoverability. Furthermore, we demonstrated the applications of the film heater in defrosting and a physical therapeutic instrument. A fast defrosting on the composite film with a transmittance of 88% was observed by applying a 9 V driving voltage for 20 s. Meanwhile, we developed a physical therapeutic instrument with two modes of thermotherapy and electronic-pulse massage by using the composite films as two electrodes, greatly decreasing the weight and power consumption compared to a traditional instrument. Therefore, Ag NW-PMMA film can be a promising candidate for diversified heating applications.

  6. Transparent conductive zinc-oxide-based films grown at low temperature by mist chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Shirahata, Takahiro [New Energy and Environmental Business Division, Toshiba Mitsubishi-Electric Industrial Systems Corporation, Kobe International Business Center (KIBC) 509, 5-5-2 Minatojima-Minami, Chuo-Ku, Kobe 650-0047 (Japan); Kawaharamura, Toshiyuki [Research Institute, Kochi University of Technology, Kami, Kochi 780-8502 (Japan); School of Systems Engineering, Kochi University of Technology, Kami, Kochi 780-8502 (Japan); Fujita, Shizuo, E-mail: fujitasz@kuee.kyoto-u.ac.jp [Photonics and Electronics Science and Engineering Center, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8520 (Japan); Orita, Hiroyuki [New Energy and Environmental Business Division, Toshiba Mitsubishi-Electric Industrial Systems Corporation, Kobe International Business Center (KIBC) 509, 5-5-2 Minatojima-Minami, Chuo-Ku, Kobe 650-0047 (Japan)

    2015-12-31

    Atmospheric pressure mist chemical vapor deposition (Mist–CVD) systems have been developed to grow zinc-oxide-based (ZnO-based) transparent conductive oxide (TCO) films. Low-resistive aluminum-doped ZnO (AZO) TCOs, showing resistivity of the order on 10{sup −4} Ωcm, previously were grown using a safe source material zinc acetate [Zn(ac){sub 2}], at a growth temperature as high as 500 °C. To grow superior TCOs at lower temperatures, we proposed the addition of NH{sub 3} to accelerate the reaction of acetylacetonate compounds. As the result, we could grow gallium-doped ZnO (GZO) TCOs with a resistivity of 2.7 × 10{sup −3} Ω cm and transmittance higher than 90% at 300 °C by using zinc acetylacetonate [Zn(acac){sub 2}] as the Zn source. To grow boron-doped ZnO (BZO) TCOs at a lower growth temperature of 200 °C, we used boron doping along with a toluene solution of diethylzinc (DEZ), that maintained high reactivity without being flammable. These BZO TCOs showed a resistivity of 1.5 × 10{sup −3} Ω cm and transmittance higher than 90%, despite the use of a non-vacuum-based open-air technology. - Highlights: • Introduction of Mist–CVD as a non-vacuum-based, safe, and cost-effective growth technology • Process evolution of the growth technology to lower the growth temperature. • Achievement of low resistive ZnO films at 200oC.

  7. Physico-chemical characteristics, nutrient composition and consumer acceptability of wheat varieties grown under organic and inorganic farming conditions.

    Science.gov (United States)

    Nitika; Punia, Darshan; Khetarpaul, N

    2008-05-01

    The aim of the investigation was to analyse physico-chemical characteristics, nutrient composition and consumer acceptability of wheat varieties grown under organic and inorganic farming conditions. The seeds of five varieties of wheat (C-306, WH-283, WH-711, WH-896 and WH-912) grown under organic and inorganic farming conditions were ground in a Junior Mill to pass through 60-mesh sieves and were stored in air-tight containers until use. Standard methods were used to estimate the physico-chemical characteristics and nutrient composition. Consumer acceptability was studied by carrying out the organoleptic evaluation of wheat chapatis, a common item in diets of the Indian population. The results of study revealed that inorganically grown wheat varieties had significantly higher 1,000-grain weight and more grain hardness as compared with organically grown wheat varieties, and a non-significant difference was observed in their gluten content, water absorption capacity and hydration capacity. On average, wheat varieties grown under inorganic conditions contained significantly higher protein and crude fibre content as compared with varieties grown under organic conditions. WH-711 variety had maximum protein content. Protein fractions (i.e. albumin, globulin, prolamin and glutelin) were significantly higher in varieties grown under inorganic conditions than those of varieties grown under organic conditions. The variety WH-711 had the highest total soluble sugars and variety WH-912 had the highest starch content. Phytic acid and polyphenol contents were significantly higher in inorganically grown wheat varieties as compared with organically grown wheat varieties. The wheat varieties grown under organic conditions had significantly higher protein and starch digestibility than the wheat grown under inorganic conditions. The data revealed that there were significant differences in total calcium and phosphorus contents of wheat varieties grown under organic and inorganic

  8. Characterization and chemical composition of epicuticular wax from banana leaves grown in Northern Thailand

    OpenAIRE

    Suporn Charumanee; Songwut Yotsawimonwat; Panee Sirisa-ard; Kiatisak Pholsongkram

    2017-01-01

    This study aimed to investigate the physicochemical properties and chemical composition of epicuticular wax extracted from leaves of Kluai Namwa, a banana cultivar which is widely grown in Northern Thailand. Its genotype was identified by a botanist. The wax was extracted using solvent extraction. The fatty acid profiles and physicochemical properties of the wax namely melting point, congealing point, crystal structures and polymorphism, hardness, color, and solubility were examin...

  9. Inverted polymer solar cells based on thin ZnO films grown by Mist chemical vapor deposition system

    Science.gov (United States)

    Biswas, Chandan; Ma, Zhu; Zhu, Xiaodan; Kawaharamura, Toshiyuki; Wang, Kang L.

    2014-10-01

    Extensive investigations have been conducted in order to synthesize high quality Zinc oxide (ZnO) thin films for numerous applications. These methods are either expensive to make or result polycrystalline thin films with low optoelectronic properties. Here we demonstrated a simple and inexpensive method to grow high quality ZnO thin films by a mist chemical vapor assisted depositing (Mist-CVD) system for inverted polymer solar cell (IPSC) application. The IPSC performance fabricated by Mist-CVD grown ZnO thin films were compared with two different Zn precursors (Zinc acetylacetonate hydrate and Zinc acetate dehydrate). Variations in IPSC performance on the growth temperature and growth time of the ZnO thin films were prominently demonstrated. The surface morphology of the ZnO films was investigated using scanning electron microscopy, atomic force microscopy and correlated with IPSC performance. The IPSC performance using two different precursors has been compared thoroughly. A 24% increase in solar cell efficiency (contributed from 21% increase in fill factor and 151% increase in shunt resistance) was achieved using Zinc acetate dehydrate compare to Zinc acetylacetonate hydrate precursor. The transmittance of ZnO thin films was evaluated by transmission spectroscopy. High performance IPSC can be fabricated using this simple and inexpensive method by synthesizing high quality thin ZnO films.

  10. Novel UV-emitting single crystalline film phosphors grown by LPE method

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Y., E-mail: zorenko@electronics.wups.lviv.u [Laboratory of optoelectronic materials, Department of Electronic, Ivan Franko National University of Lviv, Gen. Tarnavsky 107, 79017 Lviv (Ukraine); Gorbenko, V.; Savchyn, V.; Voznyak, T. [Laboratory of optoelectronic materials, Department of Electronic, Ivan Franko National University of Lviv, Gen. Tarnavsky 107, 79017 Lviv (Ukraine); Nikl, M.; Mares, J.A. [Institute of Physics AS CR, Cukrovarnicka 10, 162 53 Prague (Czech Republic); Winnacker, A. [Department of Materials Science, University of Erlangen-Nuremberg, Martensstrasse 8, D-91058 Erlangen (Germany)

    2010-03-15

    This work reports the development of new types of UV-emitting phosphors based on single crystalline films (SCF) of aluminum garnet and perovskite compounds grown by the liquid phase epitaxy method. We consider peculiarities of the growth and the luminescent and scintillation properties of the following four types of UV SCF phosphors: i) Ce-doped SCF of Y-Lu-Al-perovskites with the Ce{sup 3+} emission in the 300-450 nm range of the decay time of 16-17 ns; ii) Pr-doped SCF of Y-Lu-Al garnets and perovskites with the Pr{sup 3+} emission in the 300-400 nm and 235-330 nm ranges with the decay time of 13-19 and 7-8 ns, respectively; iii) La{sup 3+} or Sc{sup 3+} doped SCF of Y-Lu-Al-garnets, emitting in the 280-400 nm range due to formation of the La{sub Y,Lu}, Sc{sub Y,Lu} and Sc{sub Al} centers with decay time of the order of several hundreds of nanoseconds; iv) Bi{sup 3+} doped SCF of garnets with Bi{sup 3+} emission in 275-350 nm with decay time of about 1.9 {mu}s.

  11. Correlation of Crystalline and Structural Properties of C60 Thin Films Grown at Various Temperature with Charge Carrier Mobility

    Energy Technology Data Exchange (ETDEWEB)

    Singh,T.; Sarciftci, N.; Yang, H.; Yang, L.; Plochberger, B.; Sitter, H.

    2007-01-01

    Transistors fabricated from C{sub 60} films grown by hot wall epitaxy at higher substrate temperature, showed an order of magnitude increased charge carrier mobility up to 6 cm{sup 2}/V s. In this letter, the authors present an extensive study of morphology and crystallinity of the fullerene films using atomic force microscopy and grazing-incidence x-ray diffraction. A clear correlation of crystalline quality of the C{sub 60} film and charge carrier mobility was found. A higher substrate temperature leads to a single crystal-like faceted fullerene crystals. The high crystalline quality solely brings a drastic improvement in the charge carrier mobility. A gate voltage independent mobility is also observed in these devices which can be attributed to the highly conjugated nature of the C{sub 60} thin film.

  12. Ge films grown on Si substrates by molecular-beam epitaxy below 450 °C

    Science.gov (United States)

    Liu, J.; Kim, H. J.; Hul'ko, O.; Xie, Y. H.; Sahni, S.; Bandaru, P.; Yablonovitch, E.

    2004-07-01

    Ge thin films are grown on Si(001) substrates by molecular-beam epitaxy at 370 °C. The low-temperature epitaxial growth is compatible with the back-end thermal budget of current generation complementary metal-oxide-semiconductor technology, which is restricted to less than 450 °C. Reflection high-energy electron diffraction shows that single-crystal Ge thin films with smooth surfaces could be achieved below 450 °C. Double-axis x-ray θ/2θ scans also show that the epitaxial Ge films are almost fully strain-relaxed. As expected, cross-sectional transmission electron microscopy shows a network of dislocations at the interface. Hydrogen and oxide desorption techniques are proved to be necessary for improving the quality of the Ge films, which is reflected in improved minority carrier diffusion lengths and exceptionally low leakage currents.

  13. Immobilization of carbon nanotubes on functionalized graphene film grown by chemical vapor deposition and characterization of the hybrid material

    Directory of Open Access Journals (Sweden)

    Prashanta Dhoj Adhikari

    2014-01-01

    Full Text Available We report the surface functionalization of graphene films grown by chemical vapor deposition and fabrication of a hybrid material combining multi-walled carbon nanotubes and graphene (CNT–G. Amine-terminated self-assembled monolayers were prepared on graphene by the UV-modification of oxidized groups introduced onto the film surface. Amine-termination led to effective interaction with functionalized CNTs to assemble a CNT–G hybrid through covalent bonding. Characterization clearly showed no defects of the graphene film after the immobilization reaction with CNT. In addition, the hybrid graphene material revealed a distinctive CNT–G structure and p–n type electrical properties. The introduction of functional groups on the graphene film surface and fabrication of CNT–G hybrids with the present technique could provide an efficient, novel route to device fabrication.

  14. Low-relaxation spin waves in laser-molecular-beam epitaxy grown nanosized yttrium iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Lutsev, L. V., E-mail: l-lutsev@mail.ru; Korovin, A. M.; Bursian, V. E.; Gastev, S. V.; Fedorov, V. V.; Suturin, S. M.; Sokolov, N. S. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)

    2016-05-02

    Synthesis of nanosized yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) films followed by the study of ferromagnetic resonance (FMR) and spin wave propagation in these films is reported. The YIG films were grown on gadolinium gallium garnet substrates by laser molecular beam epitaxy. It has been shown that spin waves propagating in YIG deposited at 700 °C have low damping. At the frequency of 3.29 GHz, the spin-wave damping parameter is less than 3.6 × 10{sup −5}. Magnetic inhomogeneities of the YIG films give the main contribution to the FMR linewidth. The contribution of the relaxation processes to the FMR linewidth is as low as 1.2%.

  15. [Spectroscopic study on film formation mechanism and structure of composite silanes-V-Zr passive film].

    Science.gov (United States)

    Wang, Lei; Liu, Chang-sheng; Shi, Lei; An, Cheng-qiang

    2015-02-01

    A composite silanes-V-Zr passive film was overlayed on hot-dip galvanized steel. Attenuated total reflection Fourier transformed infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometer (XPS) and radio frequency glow discharge optical emission spectrometry (rf-GD-OES) were used to characterize the molecular structure of the silanes-V-Zr passive film. The mechanism of film formation was discussed: The results show that the silane molecules are crosslinked as the main film former and inorganic inhibitor is even distributed in the film. The fitting peak of 100.7 eV in XPS single Si2p energy range spectra of the composite silanes-V-Zr passive film and the widening and strengthening of the Si--O infrared absorption peak at 1100 cm(-1) indicate that the silanes were adsorbed on the surface of zinc with chemical bond of Si--O--Zn, and the silane molecules were connected with each other by bond of Si--O--Si. Two characteristic absorption peaks of amide at 1650 and 1560 cm(-1) appear in the infrared spectroscopy of the composite silanes-V-Zr passive film, and a characteristic absorption peak of epoxy groups at 910 cm(-1) disappears in the infrared spectroscopy of the passive film. The results indicate that gamma-APT can be prepared through nucleophilic ring-opening of ethylene oxide in gamma-GPT molecule to form C--N covalent bonds. The rf-GD-OES results indicate that there is a oxygen enriched layer in 0.3 microm depth of the composite silanes-V-Zr passive film. Moreover, ZrF4, ZrO2 and some inorganic matter obtained by the reaction during the forming processof the composite silanes-V-Zr passive film are distributed evenly throughout the film. According to the film composition, the physical processes and chemical reactions during the film forming process were studied by using ATR-FTIR. Based on this, the film forming mechanism was proposed.

  16. Nonstoichiometric composition shift in physical vapor deposition of CdTe thin films

    Science.gov (United States)

    Chin, Ken K.; Cheng, Zimeng; Delahoy, Alan E.

    2015-05-01

    While it is being debated whether Cd vacancy is an effective p-dopant in CdTe, and whether CdTe thin film in solar energy application should be Cd-deficient or Cd-rich, in the theory of CdTe physical vapor deposition (PVD) it has been assumed that both the source material and the thin film product is stoichiometric. To remediate the lack of effective theory, a new PVD model for CdTe photovoltaic (PV) modules is presented in this work, in which the composition of the CdTe thin film under growth is a parameter determined by the source CdTe composition as well as the growth condition. The solid phase Cd1-δTe1+δ compound under deposition temperature is treated as a solid solution with a mole of excess pure Te or Cd as solute and one mole of congruently grown CdTe as solvent. Assuming that the vapor pressure of Te2 can be calculated by using the law of solid solution PTe=H0+aH1+a2H2 round the congruent composition, where the molar number a and the constants H0, H1 and H2 as functions of temperature T are extracted from the experimental data. Thus, the mole fraction of solute in the grown CdTe thin film as well as the growth rate, as a function of the solute mole fraction in the source CdTe can be determined.

  17. Superconducting NbN films grown using pulsed laser deposition for potential application in internally shunted Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Anupama; Meng, Xiaofan; Wong, Andre; Van Duzer, Theodore [Department of Electrical Engineering and Computer Sciences and the Electronics Research Laboratory, University of California, Berkeley, CA 720 1770 (United States)

    1999-11-01

    We have grown superconducting NbN films using a pulsed KrF laser for potential use as superconducting electrodes in SNS Josephson junctions being developed for nonlatching logic applications. The NbN films show a superconducting transition of 16 K using an Nb target in background N{sub 2} gas. The T{sub c} dependence on N{sub 2} pressure in the range of 50-80 mTorr was investigated at a growth temperature of 600 deg. C. The NbN films were grown on MgO(100) and amorphous SiN{sub x}/Si substrates. In the latter case, the films had a lower T{sub c}, and appeared amorphous from x-ray diffraction measurements, while those on the MgO(100) substrates were strongly textured. AFM measurements reveal RMS surface roughness as low as 1 nm, over a 5 {mu}m x 5 {mu}m area, indicating that these films appear suitable for SNS junctions. (author)

  18. Electrical and thermal properties of PLA/CNT composite films

    OpenAIRE

    Ceregatti, Thayara; Pecharki, Paloma; PACHEKOSKI, Wagner M.; Becker,Daniela; Dalmolin, Carla

    2017-01-01

    ABSTRACT Conducting polymers presents many potential applications such as biosensors and biofuelcells. However, to be used in those devices, a thin film must be deposited onto a conducting and biocompatible substrate. In this work, carbon nanotubes (CNT) were mixed in a poly (lactic acid) - PLA - matrix with different compositions (from 0.25 to 5.0 %) in order to form conducting composites suitable to the deposition of a conducting polymer. Thermal properties of PLA/CNT composites were evalua...

  19. Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Joel Glenn [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

  20. Schottky barrier height of Ni to β-(AlxGa1-x)2O3 with different compositions grown by plasma-assisted molecular beam epitaxy

    Science.gov (United States)

    Ahmadi, Elaheh; Oshima, Yuichi; Wu, Feng; Speck, James S.

    2017-03-01

    Coherent β-(AlxGa1-x)2O3 films (x = 0, 0.038, 0.084, 0.164) were grown successfully on a Sn-doped β-Ga2O3 (010) substrate using plasma-assisted molecular beam epitaxy. Atom probe tomography, transmission electron microscopy, and high resolution x-ray diffraction were used to verify the alloy composition and high quality of the films. Schottky diodes were then fabricated using Ni as the Schottky metal. Capacitance-voltage measurements revealed a very low (current-voltage (I-V) measurements performed at temperatures varying from 300 K to 500 K on the Schottky diodes. These measurements revealed that the apparent Schottky barrier height could have similar values for different compositions of β-(AlxGa1-x)2O3. We believe this is attributed to the lateral fluctuation in the alloy’s composition. This results in a lateral variation in the barrier height. Therefore, the average Schottky barrier height extracted from I-V measurements could be similar for β-(AlxGa1-x)2O3 films with different compositions.

  1. Moisture barrier properties of xylan composite films

    Science.gov (United States)

    Amit Saxena; Thomas J. Elder; Arthur J. Ragauskas

    2011-01-01

    Moisture barrier properties of films based on xylan reinforced with several cellulosic resources including nanocrystalline cellulose, acacia bleached kraft pulp fibers and softwood kraft fibers have been evaluated. Measurements of water vapor transmission rate (WVTR) were performed by a modification of the wet cup method described by ASTM E 96-95, indicating that...

  2. Wearable near-field communication antennas with magnetic composite films

    Directory of Open Access Journals (Sweden)

    Bihong Zhan

    2017-06-01

    Full Text Available The flexible near-field communication (NFC antennas integrated with Fe3O4/ethylene-vinyl acetate copolymer (EVA magnetic films were presented, and the influence of the magnetic composite films on the performance and miniaturization capability of the NFC antennas was investigated. Theoretical analysis and experimental results show that the integration of the magnetic composite films is conducive to the miniaturization of the NFC antennas. However, the pattern design of the integrated magnetic film is very important to improve the communication performance of NFC antenna. When magnetic film covers whole antenna, the inductance (L and quality factor (Q of the NFC antenna at 13MHz are increased by 60% and 5% respectively, but the communication distance of NFC system is decreased by 70%. When the magnetic film is located at the center of the antenna, the L value, Q value and communication distance of the NFC antenna are increased by 16.5%, 15.5% and 20% respectively. It can be seen that the application of the integrated magnetic film with optimized pattern to the NFC antenna can not only reduce the size of the antenna, but also improve the overall performance of the antenna.

  3. Wearable near-field communication antennas with magnetic composite films

    Science.gov (United States)

    Zhan, Bihong; Su, Dan; Liu, Sheng; Liu, Feng

    2017-06-01

    The flexible near-field communication (NFC) antennas integrated with Fe3O4/ethylene-vinyl acetate copolymer (EVA) magnetic films were presented, and the influence of the magnetic composite films on the performance and miniaturization capability of the NFC antennas was investigated. Theoretical analysis and experimental results show that the integration of the magnetic composite films is conducive to the miniaturization of the NFC antennas. However, the pattern design of the integrated magnetic film is very important to improve the communication performance of NFC antenna. When magnetic film covers whole antenna, the inductance (L) and quality factor (Q) of the NFC antenna at 13MHz are increased by 60% and 5% respectively, but the communication distance of NFC system is decreased by 70%. When the magnetic film is located at the center of the antenna, the L value, Q value and communication distance of the NFC antenna are increased by 16.5%, 15.5% and 20% respectively. It can be seen that the application of the integrated magnetic film with optimized pattern to the NFC antenna can not only reduce the size of the antenna, but also improve the overall performance of the antenna.

  4. XPS Depth Profile Analysis of Zn3N2 Thin Films Grown at Different N2/Ar Gas Flow Rates by RF Magnetron Sputtering.

    Science.gov (United States)

    Haider, M Baseer

    2017-12-01

    Zinc nitride thin films were grown on fused silica substrates at 300 °C by radio frequency magnetron sputtering. Films were grown at different N2/Ar flow rate ratios of 0.20, 0.40, 0.60, 0.80, and 1.0. All the samples have grain-like surface morphology with an average surface roughness ranging from 4 to 5 nm and an average grain size ranging from 13 to16 nm. Zn3N2 samples grown at lower N2/Ar ratio are polycrystalline with secondary phases of ZnO present, whereas at higher N2/Ar ratio, no ZnO phases were found. Highly aligned films were achieved at N2/Ar ratio of 0.60. Hall effect measurements reveal that films are n-type semiconductors, and the highest carrier concentration and Hall mobility was achieved for the films grown at N2/Ar ratio of 0.60. X-ray photoelectron study was performed to confirm the formation of Zn-N bonds and to study the presence of different species in the film. Depth profile XPS analyses of the films reveal that there is less nitrogen in the bulk of the film compared to the nitrogen on the surface of the film whereas more oxygen is present in the bulk of the films possibly occupying the nitrogen vacancies.

  5. Pulsed laser deposition of semiconductor-ITO composite films on electric-field-applied substrates

    Energy Technology Data Exchange (ETDEWEB)

    Narazaki, Aiko; Sato, Tadatake; Kawaguchi, Yoshizo; Niino, Hiroyuki; Yabe, Akira; Sasaki, Takeshi; Koshizaki, Naoto

    2002-09-30

    The DC electric-field effect on the crystaity of II-VI semiconductor in composite systems has been investigated for CdS-ITO films fabricated via alternative pulsed laser deposition (PLD) of CdS and indium tin oxide (ITO) on electric-field-applied substrates. The alternative laser ablation was performed under irradiation of ArF excimer laser in mixture gas of helium and oxygen. The application of electric-field facilitated the preferential crystal-growth of CdS in nanometer scale at low pressure, whereas all the films grown without the field were amorphous. There is a large difference in the crystallization between the films grown on field-applied and heated substrates; the latter showed the crystal-growth with random orientations. This difference indicates that the existence of electric-field has an influence on the transformation from amorphous to crystalline phase of CdS. The driving force for the field-induced crystallization is also discussed in the light of the Joule heat.

  6. Fabrication of carbon nanotubes grown woven carbon fiber/epoxy composites and their electrical and mechanical properties

    Science.gov (United States)

    Samsur, R.; Rangari, V. K.; Jeelani, S.; Zhang, L.; Cheng, Z. Y.

    2013-06-01

    Multiwall carbon nanotubes (CNTs) were directly grown on woven carbon fibers using chemical vapor deposition technique and iron acetate as a catalyst. These CNTs grown woven carbon fibers were further infused with epoxy resin to fabricate fiber reinforced nanocomposites. Both electric and mechanical properties of these composites were studied and found that the electric resistivity of composite reduced significantly as the amount of CNTs on woven carbon fiber increased. For the neat composite without CNTs, the resistivity observed was 25 Ω.m, while it was only 0.2 Ω.m for the composite with 3.3 wt. % of CNTs grown on woven carbon fiber. The flexure test results showed a 34% increase in strength and 126% increase in stiffness for 1.65 wt. % CNTs grown on woven carbon fiber.

  7. Effect of SiO2 buffer layers on the structure of SrTiO3 films grown on silicon by pulsed laser deposition

    OpenAIRE

    Tejedor, P.; Fuenzalida, V. M.; Briones Fernández-Pola, Fernando

    1996-01-01

    Thin films of SrTiO3 were grown by pulsed laser deposition on Si and SiO2/Si at 35 and 650°C in a 50 mTorr oxygen discharge (300 V). The effect of introducing a SiO2 buffer layer between the Si substrate and the complex oxide on the crystallinity and microstructure of the SrTiO3 films was investigated at both deposition temperatures. All films grown at 35°C were amorphous. Surface morphology examination by scanning electron microscopy (SEM) showed that these films were continuous and homogene...

  8. High Crystallinity CuScO2 Delafossite Films Exhibiting Ultraviolet Photoluminescence Grown by Vapor-Liquid-Solid Tri-phase Epitaxy

    Science.gov (United States)

    Matsubara, Yuya; Makino, Takayuki; Hiraga, Hiroki; Chen, Chunlin; Tsukimoto, Susumu; Ueno, Kazunori; Kozuka, Yusuke; Ikuhara, Yuichi; Kawasaki, Masashi

    2012-01-01

    We have grown direct wide-bandgap CuScO2 thin films on MgAl2O4(111) substrates by tri-phase epitaxy employing molten Bi-O flux on the growth surface. The full width at half maximum of (0006) rocking curve is as narrow as 0.005 degrees, an order of magnitude narrower than those grown by conventional pulsed laser deposition (PLD). Transmission electron microscopy confirms the scarcity of defect structures or precipitates, which are of high density in PLD films. The films exhibit sharp near-bandedge photoluminescence at 3.3 eV, which is absent in PLD films.

  9. Determination of thicknesses of oxide films grown on titanium under argon irradiation by spectroscopic ellipsometry

    Science.gov (United States)

    Do, Ngoc-Long; Garcia-Caurel, Enric; Bérerd, Nicolas; Moncoffre, Nathalie; Gorse-Pomonti, Dominique

    2014-04-01

    In this article we present a study of the oxidation of pure titanium bulk samples under argon ion irradiation at 500 °C under rarefied air. In particular we follow the dependence of the oxide thickness as a function of the energy of argon ions. The novelty of this study consists in the range of ion energy explored, from 1 to 9 MeV. Until very recently it was commonly accepted that metal surfaces were transparent to ion beams in this low energy range (few MeV), and no surface modifications were expected. In a previous paper by the authors of this work, the formation of shallow craters in the surface of titanium was reported as a result of argon ion bombardment with energies of 2, 4 and 9 MeV under the same environmental conditions. We show here that around 3 MeV the oxide growth is unexpectedly enhanced. We think that an interplay of electronic excitations and nuclear ballistic collisions could possibly explain this enhanced oxide growth. We have used spectroscopic visible ultraviolet ellipsometry and XPS to determine the thickness of the oxide layers and characterize their optical properties. From the optical properties of the oxides we observed that for ion energies below 3-4 MeV the oxides show a dielectric-like behavior, whereas for ion energies above 3-4 MeV the oxides show a metal-like behavior. These findings indicate also that ion bombardment in this energy range may change substantially the oxygen-to-titanium ratio in the oxide films grown under irradiation leading to the formation of titanium sub-oxides.

  10. The Luminescent Properties and Atomic Structures of As-Grown and Annealed Nanostructured Silicon Rich Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    N. D. Espinosa-Torres

    2016-01-01

    Full Text Available Not long ago, we developed a theoretical model to describe a set of chemical reactions that can potentially occur during the process of obtaining Silicon Rich Oxide (SRO films, an off stoichiometry material, notwithstanding the technique used to grow such films. In order to elucidate the physical chemistry properties of such material, we suggested the chemical reactions that occur during the process of growing of SRO films in particular for the case of the Low Pressure Chemical Vapor Deposition (LPCVD technique in the aforementioned model. The present paper represents a step further with respect to the previous (published work, since it is dedicated to the calculation by Density Functional Theory (DFT of the optical and electronic properties of the as-grown and annealed SRO structures theoretically predicted on the basis of the previous work. In this work, we suggest and evaluate either some types of molecules or resulting nanostructures and we predict theoretically, by applying the DFT, the contribution that they may have to the phenomenon of luminescence (PL, which is experimentally measured in SRO films. We evaluated the optical and electronic properties of both the as-grown and the annealed structures.

  11. Unpredicted surface termination of α-Fe2O3(0001) film grown by mist chemical vapor deposition

    Science.gov (United States)

    Osaka, Shun; Kubo, Osamu; Takahashi, Kazuki; Oda, Masaya; Kaneko, Kentaro; Tabata, Hiroshi; Fujita, Shizuo; Katayama, Mitsuhiro

    2017-06-01

    We analyze the surface structure of an α-Fe2O3(0001) film grown on a c-plane sapphire substrate by mist chemical vapor deposition (CVD), which has been recently developed as a simple, safe, and cost-effective film growth method. Using coaxial impact-collision ion scattering spectroscopy, we found that the atomic-layer sequence of the surface termination of an α-Fe2O3(0001) film grown by mist CVD was Fe-O3-Fe- from the top layer. This surface termination is predicted to form in an oxygen-poor environment by density functional theory combined with a thermodynamical approach despite that the mist CVD process is performed with atmospheric-pressure air. The surface structure markedly changes after annealing above 600 °C in ultrahigh vacuum. We found that only a couple of layers from the top layer transform into Fe3O4(111) after 650 °C annealing, which would be so-called biphase reconstruction. Complete transformation into a Fe3O4(111) film occurs at 700 °C, whose atomic-layer sequence is determined to be Fe-O4-Fe3- from the top layer.

  12. Ellipsometry study on Pd thin film grown by atomic layer deposition with Maxwell–Garnett effective medium approximation model

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yihang; Zhou, Xueqi; Cao, Kun [State Key Laboratory of Digital of Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Xiuguo; Deng, Zhang [State Key Laboratory of Digital of Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu, Shiyuan, E-mail: shyliu@hust.edu.cn [State Key Laboratory of Digital of Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Shan, Bin [State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Rong, E-mail: rongchen@mail.hust.edu.cn [State Key Laboratory of Digital of Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-10-30

    Maxwell–Garnett effective medium approximation (MG-EMA) model is chosen to study Pd ultrathin film grown on Si substrate, as well as its growth on self-assembled monolayers (SAMs) modified substrate respectively. The general oscillator (GO) model with one Drude and two Lorentz oscillators is firstly applied to fix the optical constants of Pd. Compared with Pd bulk model, MG-EMA model with GO is more reliable to predict the film thickness verified by X-ray reflection test. The stable growth rate on Si substrate reveals our methods are feasible and the quartz crystal microbalance measurement confirms the stability of the ALD chamber. For Pd coverage, MG-EMA fitting result is similar to the statistical computation from scanning electron microscope when Pd ALD cycles are over 400, while large bias exists for cycles under 400, might be due to that air is not the proper filling medium between nanoparticles. Then we change the filling medium into SAMs as a comparison, better fitting performance is obtained. It is demonstrated that the filling medium between nanoparticles is important for the application of MG-EMA model. - Highlights: • Ultrathin Pd thin films were grown by atomic layer deposition. • The measurement of thin film was important to understand initial growth behavior. • Maxwell–Garnett effective medium approximation model was applied. • Pd nanoparticle size and coverage were studied. • The filling medium between nanoparticles was important for model application.

  13. Nano-structural characteristics of carbon nanotube-polymer composite films for high-amplitude optoacoustic generation.

    Science.gov (United States)

    Baac, Hyoung Won; Ok, Jong G; Lee, Taehwa; Guo, L Jay

    2015-09-14

    We demonstrate nano-structural characteristics of carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite films that can be used as highly efficient and robust ultrasound transmitters for diagnostic and therapeutic applications. An inherent architecture of the nano-composite provides unique thermal, optical, and mechanical properties that are accommodated not just for efficient energy conversion but also for extraordinary robustness against pulsed laser ablation. First, we explain a thermoacoustic transfer mechanism within the nano-composite. CNT morphologies are examined to determine a suitable arrangement for heat transfer to the surrounding PDMS. Next, we introduce an approach to enhance optical extinction of the composite films, which uses shadowed deposition of a thin Au layer through an as-grown CNT network. Finally, the transmitter robustness is quantified in terms of laser-induced damage threshold. This reveals that the CNT-PDMS films can withstand an order-of-magnitude higher optical fluence (and extinction) than a Cr film used as a reference. Such robustness is crucial to increase the maximum-available optical energy for optoacoustic excitation and pressure generation. All of these structure-originated characteristics manifest the CNT-PDMS composite films as excellent optoacoustic transmitters for high-amplitude and high-frequency ultrasound generation.

  14. Structure investigation of BN films grown by ion-beam-assisted deposition by means of polarised IR and Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ben el Mekki, M.; Djouadi, M.A.; Guiot, E.; Mortet, V. [ENSAM, Cluny (France). Lab. Bourguignon des Materiaux et Procedes; Pascallon, J.; Stambouli, V.; Bouchier, D. [Institut d' Electronique Fondamentale, Universite Paris-Sud, Orsay (France); Mestres, N. [Institut de Ciencia de Materials de Barcelona (CSIC), E-08193, Bellaterra (Spain); Nouet, G. [LERMAT, ISMRA, Caen (France)

    1999-09-01

    We present an optical investigation, by means of polarised infrared (IR) spectroscopy and Raman scattering, of the microstructure and crystallinity of mixed films of hexagonal and cubic boron nitride (h-BN and c-BN, respectively). The films were deposited on an unheated silicon substrate by the ion-beam-assisted deposition method (IBAD) at low energy (400-500 eV). The deposition temperature, due to the ion bombardment, was in the range 200-250 C at the end of the deposition process. Different film types were grown on a silicon substrate of dimensions 75 mm x 15 mm by changing the ion (nitrogen+argon) to atom (thermal boron) arrival ratio, {phi}{sub ion}/{phi}{sub B}, in the range 0.69-3. Polarised IR reflectivity (PIRR) spectra were acquired at different positions on the BN film (different arrival ratios {phi}{sub ion}/{phi}{sub B}) and show an important upwards shift of transverse optical (TO) and longitudinal optical (LO) phonons of the twofold degenerated mode E{sub 1u} of the sp{sup 2} phase at the transition zone from sp{sup 2} to sp{sup 3} phases. Several processes can shift the IR phonon peaks, including the degree of crystallinity, film thickness, film stoichiometry and intrinsic stress. The micro-Raman results and the full-width at half-maximum values of TO phonons of the E{sub 1u} mode show that the BN film has a similar crystallinity in all regions. The effect of the film thickness was shown by using a microstructure-dependent model for the IR anisotropic effective dielectric function of thin films. (orig.)

  15. Unconventional magnetization of Fe3O4 thin film grown on amorphous SiO2 substrate

    Directory of Open Access Journals (Sweden)

    Jia-Xin Yin

    2016-06-01

    Full Text Available High quality single crystal Fe3O4 thin films with (111 orientation had been prepared on amorphous SiO2 substrate by pulsed laser deposition. The magnetization properties of the films are found to be unconventional. The Verwey transition temperature derived from the magnetization jump is around 140K, which is higher than the bulk value and it can be slightly suppressed by out-plane magnetic field; the out-of-plane magnetization, which is unexpectedly higher than the in-plane value, is also significantly increased as compared with the bulk value. Our findings highlight the unusual magnetization of Fe3O4 thin film grown on the amorphous SiO2 substrate.

  16. Effects of nitrogen on the growth and optical properties of ZnO thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J B; Thomas, M A; Soo, Y C; Kandel, H; Chen, T P [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States)

    2009-08-07

    ZnO thin films were grown using pulsed laser deposition by ablating a Zn target in various mixtures of O{sub 2} and N{sub 2}. The presence of N{sub 2} during deposition was found to affect the growth of the ZnO thin films and their optical properties. Small N{sub 2} concentrations during growth led to strong acceptor-related photoluminescence (PL), while larger concentrations affected both the intensity and temperature dependence of the emission peaks. In addition, the PL properties of the annealed ZnO thin films are associated with the N{sub 2} concentration during their growth. The possible role of nitrogen in ZnO growth and annealing is discussed.

  17. Positive magnetoresistance in ferromagnetic Nd-doped In2O3 thin films grown by pulse laser deposition

    KAUST Repository

    Xing, G. Z.

    2014-05-23

    We report the magnetic and magnetotransport properties of (In 0.985Nd0.015)2O2.89 thin films grown by pulse laser deposition. The clear magnetization hysteresis loops with the complementary magnetic domain structure reveal the intrinsic room temperature ferromagnetism in the as-prepared films. The strong sp-f exchange interaction as a result of the rare earth doping is discussed as the origin of the magnetotransport behaviours. A positive magnetoresistance (∼29.2%) was observed at 5 K and ascribed to the strong ferromagnetic sp-f exchange interaction in (In0.985Nd0.015)2O 2.89 thin films due to a large Zeeman splitting in an external magnetic field of 50 KOe. © 2014 AIP Publishing LLC.

  18. Effect of heat treatment on microstructural and optical properties of CBD grown Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chandramohan, R., E-mail: rathinam.chandramohan@gmail.com [Department of Physics, Sree Sevugan Annamalai College, College Road, Devakottai 630303 (India); Vijayan, T.A. [Department of Physics, Sree Sevugan Annamalai College, College Road, Devakottai 630303 (India); Arumugam, S.; Ramalingam, H.B. [Department of Physics, Government Arts College, Udumalpet 642126 (India); Dhanasekaran, V.; Sundaram, K.; Mahalingam, T. [Department of Physics, Alagappa University, Karaikudi 630003 (India)

    2011-02-15

    Research highlights: > Effect of annealing temperature on Al-doped ZnO thin films. > Microstructural properties of Al-doped ZnO thin films. > Optical constants are found to increase with increase of heat treatment. - Abstract: Investigations on the effect of annealing temperature on the structural, optical properties and morphology of Al-doped ZnO thin films deposited on glass substrate by chemical bath deposition have been carried out. X-ray diffraction studies revealed that deposited films are in polycrystalline nature with hexagonal structure along the (0 0 2) crystallographic plane. Microstructural properties of films such as crystallite size, texture coefficient, stacking fault probability and microstrain were calculated from predominant (0 0 2) diffraction lines. The UV-Vis-NIR spectroscopy studies revealed that all the films have high optical transmittance (>60%) in the visible range. The optical band gap values are found to be in the range of 3.25-3.31 eV. Optical constants have been estimated and the values of n and k are found to increase with increase of heat treatment. The films have increased transmittance with increase of heat treatment. Al-doped ZnO thin films fabricated by this simple and economic chemical bath deposition technique without using any carrier gas are found to be good in structural and optical properties which are desirable for photovoltaic applications. Scanning electron microscopic images revealed that the hexagonal shaped grains that occupy the entire surface of the film with its near stoichiometric composition.

  19. Structure of Stoichiometric and Oxygen-Rich Ultrathin FeO(111) Films Grown on Pd(111)

    Energy Technology Data Exchange (ETDEWEB)

    Zeuthen, Helene; Kudernatsch, Wilhelmine; Peng, Guowen; Merte, Lindsay R.; Ono, Luis K.; Lammich, Lutz; Bai, Yunhai; Grabow, Lars C.; Mavrikakis, Manos; Wendt, Stefan; Besenbacher, Flemming

    2013-07-25

    Monolayer thin FeO(111) films were grown on Pd(111) and oxidized by atomic oxygen (O). The stoichiometric and oxidized films were studied in detail by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. Compared to the previously studied FeO(111)/Pt(111) system, small structural differences were observed for stoichiometric FeO monolayer films. Upon O exposure, the stoichiometric FeO film reconstructs, leading to the formation of new O-rich structures incorporating increasing amounts of additional O atoms. At low O exposures, the STM images exhibit bright features of regularly sized triangular structures assigned to O-adatom dislocation loops. A model of this O-rich structure composed of four-fold O-coordinated Fe atoms is proposed and confirmed by DFT calculations. Furthermore, these O dislocation loops induce the inversion of the FeO film and enclose portions of the film in which the order of the high-symmetry domains is inverted. For higher O exposures, the formation of FeO2–x islands coexisting with O-adatom dislocations and stoichiometric FeO patches was observed. Finally, these FeO2–x islands are reminiscent of the O-rich structures previously reported for FeO supported on Pt(111) and are catalytically active toward CO oxidation.

  20. Thin yttrium iron garnet films grown by pulsed laser deposition: Crystal structure, static, and dynamic magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, N. S., E-mail: nsokolov@fl.ioffe.ru; Fedorov, V. V.; Korovin, A. M.; Suturin, S. M.; Baranov, D. A.; Gastev, S. V.; Krichevtsov, B. B.; Bursian, V. E.; Lutsev, L. V. [Ioffe Physical-Technical Institute of Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Maksimova, K. Yu.; Grunin, A. I. [Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation); Tabuchi, M. [Synchrotron Radiation Research Center, Nagoya University, Nagoya 464-8603 (Japan)

    2016-01-14

    Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y{sub 3}Fe{sub 5}O{sub 12} (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films.

  1. Raman analyses of residual stress in diamond thin films grown on Ti6Al4V alloy

    Directory of Open Access Journals (Sweden)

    Adriana F. Azevedo

    2003-01-01

    Full Text Available The stress evolution in diamond films grown on Ti6Al4V was investigated in order to develop a comprehensive view of the residual stress formation. Residual stress is composed of intrinsic stress induced during diamond film growth and extrinsic stress caused by the different thermal expansion coefficients between the film and substrate. In the coalescence stage it has been observed that the residual stress is dominated by the microstructure, whereas on continuous films, the thermal stress is more important. In this work diamond thin films with small grain size and good size and good quality were obtained in a surface wave-guide microwave discharge, the Surfatron system, with a negative bias voltage applied between the plasma shell and substrate. For above of -100V applied bias, the ratio of carbon sp³/sp² bond may increase and the nucleation rate increase arising the high value at the -250V applied bias. Stress measurements and sp³ content in the film were studied by Raman scattering spectroscopy. The total residual stress is compressive and varied from -1.52 to -1.48 GPa between 0 and -200 V applied bias, respectively, and above the -200 V, the compressive residual stress increased drastically to -1.80 GPa. The diamond nucleation density was evaluated by top view SEM images.

  2. Structural and optoelectrical properties of Ga-doped ZnO semiconductor thin films grown by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J.; Zhong, Z.Y. [College of Electronic Information Engineering, South-Central University for Nationalities (SCUN), Wuhan (China)

    2012-09-15

    Transparent conductive gallium-doped zinc oxide (Ga-doped ZnO) films were prepared on glass substrate by magnetron sputtering. The influence of substrate temperature on structural, optoelectrical and surface properties of the films were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), spectrophotometer, four-point probe and goniometry, respectively. Experimental results show that all the films are found to be oriented along the c-axis. The grain size and optical transmittance of the films increase with increasing substrate temperature. The average transmittance in the visible wavelength range is above 83% for all the samples. It is observed that the optoelectrical property is correlated with the film structure. The Ga-doped ZnO film grown at the substrate temperature of 400 C has the highest figure of merit of 1.25 x 10{sup -2} {Omega}{sup -1}, the lowest resistivity of 1.56 x 10{sup -3} {Omega}.cm and the highest surface energy of 32.3 mJ/m{sup 2}. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. SnO{sub 2} thin films grown by atomic layer deposition using a novel Sn precursor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Min-Jung [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 (Korea, Republic of); Cho, Cheol Jin [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744 (Korea, Republic of); Kim, Kwang-Chon; Pyeon, Jung Joon [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Park, Hyung-Ho [Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 (Korea, Republic of); Kim, Hyo-Suk; Han, Jeong Hwan; Kim, Chang Gyoun; Chung, Taek-Mo [Division of Advanced Materials, Korea Research Institute of Chemical Technology (KRICT), Daejeon, 305-600 (Korea, Republic of); Park, Tae Joo [Department of Materials Science and Engineering, Hanyang University, Ansan, 426-791 (Korea, Republic of); Kwon, Beomjin [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Jeong, Doo Seok; Baek, Seung-Hyub [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Department of Nanomaterials, Korea University of Science and Technology, Daejeon, 305-333 (Korea, Republic of); Kang, Chong-Yun; Kim, Jin-Sang [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Kim, Seong Keun, E-mail: s.k.kim@kist.re.kr [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Department of Nanomaterials, Korea University of Science and Technology, Daejeon, 305-333 (Korea, Republic of)

    2014-11-30

    Highlights: • We developed a new ALD process for SnO{sub 2} films using dimethylamino-2-methyl-2-propoxy-tin(II) as a novel Sn precursor. • The SnO{sub 2} films grown from Sn(dmamp){sub 2} has negligible impurity contents. • Sn ions in the films had a single binding state corresponding to Sn{sup 4+} in SnO{sub 2}. - Abstract: SnO{sub 2} thin films were grown by atomic layer deposition (ALD) with dimethylamino-2-methyl-2-propoxy-tin(II) (Sn(dmamp){sub 2}) and O{sub 3} in a temperature range of 100–230 °C. The ALD window was found to be in the range of 100–200 °C. The growth per cycle of the films in the ALD window increased with temperature in the range from 0.018 to 0.042 nm/cycle. Above 230 °C, the self-limiting behavior which is a unique characteristic of ALD, was not observed in the growth because of the thermal decomposition of the Sn(dmamp){sub 2} precursor. The SnO{sub 2} films were amorphous in the ALD window and exhibited quite a smooth surface. Sn ions in all films had a single binding state corresponding to Sn{sup 4+} in SnO{sub 2}. The concentration of carbon and nitrogen in the all SnO{sub 2} films was below the detection limit of the auger electron spectroscopy technique and a very small amount of carbon, nitrogen, and hydrogen was detected by secondary ions mass spectroscopy only. The impurity contents decreased with increasing the growth temperature. This is consistent with the increase in the density of the SnO{sub 2} films with respect to the growth temperature. The ALD process with Sn(dmamp){sub 2} and O{sub 3} shows excellent conformality on a hole structure with an aspect ratio of ∼9. This demonstrates that the ALD process with Sn(dmamp){sub 2} and O{sub 3} is promising for growth of robust and highly pure SnO{sub 2} films.

  4. Waveguiding thin Y2O3 films grown on sapphire substrates

    NARCIS (Netherlands)

    Kuzminykh, Y.; Bär, S.; Scheife, H.; Huber, G.; Apostolopoulos, V.; Pollnau, Markus

    Thin crystalline and amorphous yttria films have been produced using pulsed laser deposition and electron beam evaporation methods. Planar waveguiding in amorphous yttria films produced by electron beam evaporation has been demonstrated.

  5. Waveguiding thin Y2O3 films grown on sapphire substrates

    OpenAIRE

    Kuzminykh, Y.; Bär, S.; Scheife, H.; Huber, G; Apostolopoulos, V.; Pollnau, Markus

    2004-01-01

    Thin crystalline and amorphous yttria films have been produced using pulsed laser deposition and electron beam evaporation methods. Planar waveguiding in amorphous yttria films produced by electron beam evaporation has been demonstrated.

  6. Bioinspired Transparent Laminated Composite Film for Flexible Green Optoelectronics.

    Science.gov (United States)

    Lee, Daewon; Lim, Young-Woo; Im, Hyeon-Gyun; Jeong, Seonju; Ji, Sangyoon; Kim, Yong Ho; Choi, Gwang-Mun; Park, Jang-Ung; Lee, Jung-Yong; Jin, Jungho; Bae, Byeong-Soo

    2017-07-19

    Herein, we report a new version of a bioinspired chitin nanofiber (ChNF) transparent laminated composite film (HCLaminate) made of siloxane hybrid materials (hybrimers) reinforced with ChNFs, which mimics the nanofiber-matrix structure of hierarchical biocomposites. Our HCLaminate is produced via vacuum bag compressing and subsequent UV-curing of the matrix resin-impregnated ChNF transparent paper (ChNF paper). It is worthwhile to note that this new type of ChNF-based transparent substrate film retains the strengths of the original ChNF paper and compensates for ChNF paper's drawbacks as a flexible transparent substrate. As a result, compared with high-performance synthetic plastic films, such as poly(ethylene terephthalate), poly(ether sulfone), poly(ethylene naphthalate), and polyimide, our HCLaminate is characterized to exhibit extremely smooth surface topography, outstanding optical clarity, high elastic modulus, high dimensional stability, etc. To prove our HCLaminate as a substrate film, we use it to fabricate flexible perovskite solar cells and a touch-screen panel. As far as we know, this work is the first to demonstrate flexible optoelectronics, such as flexible perovskite solar cells and a touch-screen panel, actually fabricated on a composite film made of ChNF. Given its desirable macroscopic properties, we envision our HCLaminate being utilized as a transparent substrate film for flexible green optoelectronics.

  7. Nanocellulose-Zeolite Composite Films for Odor Elimination.

    Science.gov (United States)

    Keshavarzi, Neda; Mashayekhy Rad, Farshid; Mace, Amber; Ansari, Farhan; Akhtar, Farid; Nilsson, Ulrika; Berglund, Lars; Bergström, Lennart

    2015-07-08

    Free standing and strong odor-removing composite films of cellulose nanofibrils (CNF) with a high content of nanoporous zeolite adsorbents have been colloidally processed. Thermogravimetric desorption analysis (TGA) and infrared spectroscopy combined with computational simulations showed that commercially available silicalite-1 and ZSM-5 have a high affinity and uptake of volatile odors like ethanethiol and propanethiol, also in the presence of water. The simulations showed that propanethiol has a higher affinity, up to 16%, to the two zeolites compared with ethanethiol. Highly flexible and strong free-standing zeolite-CNF films with an adsorbent loading of 89 w/w% have been produced by Ca-induced gelation and vacuum filtration. The CNF-network controls the strength of the composite films and 100 μm thick zeolite-CNF films with a CNF content of less than 10 vol % displayed a tensile strength approaching 10 MPa. Headspace solid phase microextraction (SPME) coupled to gas chromatography-mass spectroscopy (GC/MS) analysis showed that the CNF-zeolite films can eliminate the volatile thiol-based odors to concentrations below the detection ability of the human olfactory system. Odor removing zeolite-cellulose nanofibril films could enable improved transport and storage of fruits and vegetables rich in odors, for example, onion and the tasty but foul-smelling South-East Asian Durian fruit.

  8. Bonding structure and morphology of chromium oxide films grown by pulsed-DC reactive magnetron sputter deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gago, R., E-mail: rgago@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, E-28049 Madrid (Spain); Vinnichenko, M. [Fraunhofer-Institut für Keramische Technologien und Systeme IKTS, D-01277 Dresden (Germany); Hübner, R. [Helmholtz-Zentrum Dresden – Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden (Germany); Redondo-Cubero, A. [Departamento de Física Aplicada and Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, E-28049 Madrid (Spain)

    2016-07-05

    Chromium oxide (CrO{sub x}) thin films were grown by pulsed-DC reactive magnetron sputter deposition in an Ar/O{sub 2} discharge as a function of the O{sub 2} fraction in the gas mixture (ƒ) and for substrate temperatures, T{sub s}, up to 450 °C. The samples were analysed by Rutherford backscattering spectrometry (RBS), spectroscopic ellipsometry (SE), atomic force microscopy (AFM), scanning (SEM) and transmission (TEM) electron microscopy, X-ray diffraction (XRD), and X-ray absorption near-edge structure (XANES). On unheated substrates, by increasing ƒ the growth rate is higher and the O/Cr ratio (x) rises from ∼2 up to ∼2.5. Inversely, by increasing T{sub s} the atomic incorporation rate drops and x falls to ∼1.8. XRD shows that samples grown on unheated substrates are amorphous and that nanocrystalline Cr{sub 2}O{sub 3} (x = 1.5) is formed by increasing T{sub s}. In amorphous CrO{sub x}, XANES reveals the presence of multiple Cr environments that indicate the growth of mixed-valence oxides, with progressive promotion of hexavalent states with ƒ. XANES data also confirms the formation of single-phase nanocrystalline Cr{sub 2}O{sub 3} at elevated T{sub s}. These structural changes also reflect on the optical and morphological properties of the films. - Highlights: • XANES of CrO{sub x} thin films grown by pulsed-DC reactive magnetron sputtering. • Identification of mixed-valence amorphous CrO{sub x} oxides on unheated substrates. • Promotion of amorphous chromic acid (Cr{sup VI}) by increasing O{sub 2} partial pressure. • Production of single-phase Cr{sub 2}O{sub 3} films by increasing substrate temperature. • Correlation of bonding structure with morphological and optical properties.

  9. XPS analysis and structural and morphological characterization of Cu{sub 2}ZnSnS{sub 4} thin films grown by sequential evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Gordillo, G. [Departamento de Física, Universidad Nacional de Colombia, Bogotá (Colombia); Calderón, C., E-mail: clcalderont@unal.edu.co [Departamento de Física, Universidad Nacional de Colombia, Bogotá (Colombia); Bartolo-Pérez, P. [Departamento de Física Aplicada, CINVESTAV-IPN, Mérida, Yuc. (Mexico)

    2014-06-01

    This work describes a procedure to grow single phase Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films with tetragonal-kesterite type structure, through sequential evaporation of the elemental metallic precursors under sulphur vapor supplied from an effusion cell. X-ray diffraction analysis (XRD) is mostly used for phase identification but cannot clearly distinguish the formation of secondary phases such as Cu{sub 2}SnS{sub 3} (CTS) because both compounds have the same diffraction pattern; therefore the use of a complementary technique is needed. Raman scattering analysis was used to distinguish these phases. The influence of the preparation conditions on the morphology and phases present in CZTS thin films were investigated through measurements of scanning electron microscopy (SEM) and XRD, respectively. From transmittance measurements, the energy band gap of the CZTS films was estimated to be around 1.45 eV. The limitation of XRD to identify some of the remaining phases after the growth process are investigated and the results of Raman analysis on the phases formed in samples grown by this method are presented. Further, the influence of the preparation conditions on the homogeneity of the chemical composition in the volume was studied by X-ray photoelectron spectroscopy (XPS) analysis.

  10. Optical properties and structure of HfO{sub 2} thin films grown by high pressure reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    MartInez, F L [Departamento de Electronica y TecnologIa de Computadoras, Universidad Politecnica de Cartagena, Campus Universitario Muralla del Mar, E-30202 Cartagena (Spain); Toledano-Luque, M [Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, E-28040 Madrid (Spain); GandIa, J J [Departamento de EnergIa, CIEMAT, Avda. Complutense 22, E-28040 Madrid (Spain); Carabe, J [Departamento de EnergIa, CIEMAT, Avda. Complutense 22, E-28040 Madrid (Spain); Bohne, W [Hahn-Meitner-Institut Berlin, Abteilung SF4, D-14109 Berlin (Germany); Roehrich, J [Hahn-Meitner-Institut Berlin, Abteilung SF4, D-14109 Berlin (Germany); Strub, E [Hahn-Meitner-Institut Berlin, Abteilung SF4, D-14109 Berlin (Germany); Martil, I [Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2007-09-07

    Thin films of hafnium oxide (HfO{sub 2}) have been grown by high pressure reactive sputtering on transparent quartz substrates (UV-grade silica) and silicon wafers. Deposition conditions were adjusted to obtain polycrystalline as well as amorphous films. Optical properties of the films deposited on the silica substrates were investigated by transmittance and reflectance spectroscopy in the ultraviolet, visible and near infrared range. A numerical analysis method that takes into account the different surface roughness of the polycrystalline and amorphous films was applied to calculate the optical constants (refractive index and absorption coefficient). Amorphous films were found to have a higher refractive index and a lower transparency than polycrystalline films. This is attributed to a higher density of the amorphous samples, which was confirmed by atomic density measurements performed by heavy-ion elastic recoil detection analysis. The absorption coefficient gave an excellent fit to the Tauc law (indirect gap), which allowed a band gap value of 5.54 eV to be obtained. The structure of the films (amorphous or polycrystalline) was found to have no significant influence on the nature of the band gap. The Tauc plots also give information about the structure of the films, because the slope of the plot (the Tauc parameter) is related to the degree of order in the bond network. The amorphous samples had a larger value of the Tauc parameter, i.e. more order than the polycrystalline samples. This is indicative of a uniform bond network with percolation of the bond chains, in contrast to the randomly oriented polycrystalline grains separated by grain boundaries.

  11. Mechanical and electrical properties of calcinated tea-based cellulose composite films

    Science.gov (United States)

    Tippabattini, Jayaramudu; Kim, Jung Woong; Ko, Hyun-U.; Kafy, Abdullahil; Li, Yaguang; Kim, Jaehwan

    2017-04-01

    In the present investigation, calcinated tea-based cellulose composite films were fabricated via solution casting technique. The fabricated films were characterized by using Fourier transform infrared spectroscopy and differential scanning calorimetry. The effect of calcinated tea loading on the properties of the calcinated tea-based cellulose composite films was studied. The results were showed that the calcinated tea composite films display better mechanical properties and dielectric constant than the pure cellulose films.

  12. Preparation and characterisation of compositionally graded SmCo films

    Directory of Open Access Journals (Sweden)

    Andre Dias

    2017-05-01

    Full Text Available A compositionally graded SmCo film has been prepared by magnetron sputtering using a Co target partially covered by a Sm foil. The film was deposited onto a 100 mm thermally oxidised Si substrate and then annealed ex-situ. The SmCo film has been used as a test sample to validate an in-house developed scanning MOKE (Magneto-Optic Kerr effect system incorporating a pulsed magnetic field source capable of producing fields as high as 10 T. A 2D array of hysteresis loops was measured across the entire wafer. The evolution in coercivity measured along a selected 1D strip of the sample is correlated with changes in composition and crystallographic structures measured using Energy Dispersive Spectroscopy and X-ray diffraction. The high field Scanning MOKE system holds much potential for optimizing the extrinsic properties of known hard magnetic phases as well as in the search for new hard magnetic phases.

  13. Preparation and characterisation of compositionally graded SmCo films

    Science.gov (United States)

    Dias, Andre; Gomez, Gabriel; Givord, Dominique; Bonfim, Marlio; Dempsey, Nora M.

    2017-05-01

    A compositionally graded SmCo film has been prepared by magnetron sputtering using a Co target partially covered by a Sm foil. The film was deposited onto a 100 mm thermally oxidised Si substrate and then annealed ex-situ. The SmCo film has been used as a test sample to validate an in-house developed scanning MOKE (Magneto-Optic Kerr effect) system incorporating a pulsed magnetic field source capable of producing fields as high as 10 T. A 2D array of hysteresis loops was measured across the entire wafer. The evolution in coercivity measured along a selected 1D strip of the sample is correlated with changes in composition and crystallographic structures measured using Energy Dispersive Spectroscopy and X-ray diffraction. The high field Scanning MOKE system holds much potential for optimizing the extrinsic properties of known hard magnetic phases as well as in the search for new hard magnetic phases.

  14. Graphene/Ionic liquid composite films and ion exchange.

    Science.gov (United States)

    Mo, Yufei; Wan, Yunfang; Chau, Alicia; Huang, Fuchuan

    2014-06-27

    Wettability of graphene is adjusted by the formation of various ionic surfaces combining ionic liquid (IL) self-assembly with ion exchange. The functionalized ILs were designed and synthesized with the goal of obtaining adjustable wettability. The wettability of the graphene surface bearing various anions was measured systematically. The effect of solvent systems on ion exchange ratios on the graphene surface has also been investigated. Meanwhile, the mechanical properties of the graphene/IL composite films were investigated on a nanometer scale. The elasticity and adhesion behavior of the thin film was determined with respected to the indentation deformation by colloid probe nanoindentation method. The results indicate that anions played an important role in determining graphene/IL composite film properties. In addition, surface wetting and mechanics can be quantitatively determined according to the counter-anions on the surface. This study might suggest an alternate way for quantity detection of surface ions by surface force.

  15. Gelatin-Pectin Composite Films from Polyion Complex Hydrogels

    Science.gov (United States)

    Composite films from gelatin and low-methoxyl pectin were prepared by either ionic complexation or covalent cross-linking. The ionic interactions between positively charged gelatin and negatively charged pectin produced physically reversible hydrogels. The resultant homogeneous gels had improved mec...

  16. Nanostructure composite film for sensor controls of humidity

    Directory of Open Access Journals (Sweden)

    Kovalenko K. L.

    2009-10-01

    Full Text Available Received nanostructure of the composite film allows to create integrated sensor controls of humidity with high sensitivity, stable in time, with linear dependence of capacity from relative humidity practically in all range of its change (3 to 100% and keeping working capacity at low temperatures up to –35°С.

  17. Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Deb, K.; Bera, A.; Saha, B., E-mail: biswajit.physics@gmail.com [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Bhowmik, K. L. [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Department of Chemistry, Bir Bikram Memorial College, Agartala, West Tripura 799004 (India); Chattopadhyay, K. K. [Department of Physics, Jadavpur University, Kolkata 700 032 (India)

    2016-05-23

    Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

  18. Ternary carbon composite films for supercapacitor applications

    Science.gov (United States)

    Tran, Minh-Hai; Jeong, Hae Kyung

    2017-09-01

    A simple, binder-free, method of making supercapacitor electrodes is introduced, based on modification of activated carbon with graphite oxide and carbon nanotubes. The three carbon precursors of different morphologies support each other to provide outstanding electrochemical performance, such as high capacitance and high energy density. The ternary carbon composite shows six times higher specific capacitance compared to that of activated carbon itself with high retention. The excellent electrochemical properties of the ternary composite attribute to the high surface area of 1933 m2 g-1 and low equivalent series resistance of 2 Ω, demonstrating that it improve the electrochemical performance for supercapacitor applications.

  19. Vapor Grown Carbon Fiber/Phenolic Matrix Composites for Rocket Nozzles and Heat Shields

    Science.gov (United States)

    Patton, R. D.; Pittman, C. U., Jr.; Wang, L.; Day, A.; Hill, J. R.

    2001-01-01

    The ablation and mechanical and thermal properties of vapor grown carbon fiber (VGCF)/phenolic resin composites were evaluated to determine the potential of using this material in solid rocket motor nozzles. Composite specimens with varying VGCF loading (30%-50% wt) including one sample with ex-rayon carbon fiber plies were prepared and exposed to a plasma torch for 20 s with a heat flux of 16.5 MW/sq m at approximately 1650 C. Low erosion rates and little char formation were observed, confirming that these materials were promising for rocket motor nozzle materials. When fiber loadings increased, mechanical properties and ablative properties improved. The VGCF composites had low thermal conductivities (approximately 0.56 W/m-C) indicating they were good insulating materials. If a 65% fiber loading in VGCF composite can be achieved, then ablative properties are projected to be comparable to or better than the composite material currently used on the Space Shuttle Reusable Solid Rocket Motor (RSRM).

  20. Characterization and chemical composition of epicuticular wax from banana leaves grown in Northern Thailand

    Directory of Open Access Journals (Sweden)

    Suporn Charumanee

    2017-08-01

    Full Text Available This study aimed to investigate the physicochemical properties and chemical composition of epicuticular wax extracted from leaves of Kluai Namwa, a banana cultivar which is widely grown in Northern Thailand. Its genotype was identified by a botanist. The wax was extracted using solvent extraction. The fatty acid profiles and physicochemical properties of the wax namely melting point, congealing point, crystal structures and polymorphism, hardness, color, and solubility were examined and compared to those of beeswax, carnauba wax and paraffin wax. The results showed that the genotype of Kluai Namwa was Musa acuminata X M. balbisiana (ABB group cv. Pisang Awak. The highest amount of wax extracted was 274 μg/cm2 surface area. The fatty acid composition and the physicochemical properties of the wax were similar to those of carnauba wax. It could be suggested that the banana wax could be used as a replacement for carnauba wax in various utilizing areas.

  1. Effects of Various Parameters on Structural and Optical Properties of CBD-Grown ZnS Thin Films: A Review

    Science.gov (United States)

    Sinha, Tarkeshwar; Lilhare, Devjyoti; Khare, Ayush

    2018-02-01

    Zinc sulfide (ZnS) thin films deposited by chemical bath deposition (CBD) technique have proved their capability in a wide area of applications including electroluminescent and display devices, solar cells, sensors, and field emitters. These semiconducting thin films have attracted a much attention from the scientific community for industrial and research purposes. In this article, we provide a comprehensive review on the effect of various parameters on various properties of CBD-grown ZnS films. In the first part, we discuss the historical background of ZnS, its basic properties, and the advantages of the CBD technique. Detailed discussions on the film growth, structural and optical properties of ZnS thin films affected by various parameters, such as bath temperature and concentration, deposition time, stirring speed, complexing agents, pH value, humidity in the environment, and annealing conditions, are also presented. In later sections, brief information about the recent studies and findings is also added to explore the scope of research work in this field.

  2. Structural, Optical Constants and Photoluminescence of ZnO Thin Films Grown by Sol-Gel Spin Coating

    Directory of Open Access Journals (Sweden)

    Abdel-Sattar Gadallah

    2013-01-01

    Full Text Available We report manufacturing and characterization of low cost ZnO thin films grown on glass substrates by sol-gel spin coating method. For structural properties, X-ray diffraction measurements have been utilized for evaluating the dominant orientation of the thin films. For optical properties, reflectance and transmittance spectrophotometric measurements have been done in the spectral range from 350 nm to 2000 nm. The transmittance of the prepared thin films is 92.4% and 88.4%. Determination of the optical constants such as refractive index, absorption coefficient, and dielectric constant in this wavelength range has been evaluated. Further, normal dispersion of the refractive index has been analyzed in terms of single oscillator model of free carrier absorption to estimate the dispersion and oscillation energy. The lattice dielectric constant and the ratio of free carrier concentration to free carrier effective mass have been determined. Moreover, photoluminescence measurements of the thin films in the spectral range from 350 nm to 900 nm have been presented. Electrical measurements for resistivity evaluation of the films have been done. An analysis in terms of order-disorder of the material has been presented to provide more consistency in the results.

  3. Effects of Various Parameters on Structural and Optical Properties of CBD-Grown ZnS Thin Films: A Review

    Science.gov (United States)

    Sinha, Tarkeshwar; Lilhare, Devjyoti; Khare, Ayush

    2017-10-01

    Zinc sulfide (ZnS) thin films deposited by chemical bath deposition (CBD) technique have proved their capability in a wide area of applications including electroluminescent and display devices, solar cells, sensors, and field emitters. These semiconducting thin films have attracted a much attention from the scientific community for industrial and research purposes. In this article, we provide a comprehensive review on the effect of various parameters on various properties of CBD-grown ZnS films. In the first part, we discuss the historical background of ZnS, its basic properties, and the advantages of the CBD technique. Detailed discussions on the film growth, structural and optical properties of ZnS thin films affected by various parameters, such as bath temperature and concentration, deposition time, stirring speed, complexing agents, pH value, humidity in the environment, and annealing conditions, are also presented. In later sections, brief information about the recent studies and findings is also added to explore the scope of research work in this field.

  4. Efficient etching-free transfer of high quality, large-area CVD grown graphene onto polyvinyl alcohol films

    Energy Technology Data Exchange (ETDEWEB)

    Marta, Bogdan; Leordean, Cosmin [Babes-Bolyai University, Interdisciplinary Research Institute in Bio-Nano-Sciences, Nanobiophotonics and Laser Microspectroscopy Center, Treboniu Laurian Str. 42, Cluj-Napoca 400271 (Romania); Istvan, Todor [Babes-Bolyai University, Faculty of Physics, Biomolecular Physics Department, M Kogalniceanu Str. 1, Cluj-Napoca 400084 (Romania); Botiz, Ioan [Babes-Bolyai University, Interdisciplinary Research Institute in Bio-Nano-Sciences, Nanobiophotonics and Laser Microspectroscopy Center, Treboniu Laurian Str. 42, Cluj-Napoca 400271 (Romania); Astilean, Simion, E-mail: simion.astilean@phys.ubbcluj.ro [Babes-Bolyai University, Interdisciplinary Research Institute in Bio-Nano-Sciences, Nanobiophotonics and Laser Microspectroscopy Center, Treboniu Laurian Str. 42, Cluj-Napoca 400271 (Romania); Babes-Bolyai University, Faculty of Physics, Biomolecular Physics Department, M Kogalniceanu Str. 1, Cluj-Napoca 400084 (Romania)

    2016-02-15

    Graphical abstract: - Highlights: • One-step dry transfer method of CVD grown graphene onto PVA films. • Investigation of graphene quality and number of layers of the synthesized and transferred graphene. • Promising scalability and good quality of transferred graphene onto flexible transparent polymers. - Abstract: Graphene transfer is a procedure of paramount importance for the production of graphene-based electronic devices. The transfer procedure can affect the electronic properties of the transferred graphene and can be detrimental for possible applications both due to procedure induced defects which can appear and due to scalability of the method. Hence, it is important to investigate new transfer methods for graphene that are less time consuming and show great promise. In the present study we propose an efficient, etching-free transfer method that consists in applying a thin polyvinyl alcohol layer on top of the CVD grown graphene on Cu and then peeling-off the graphene onto the polyvinyl alcohol film. We investigate the quality of the transferred graphene before and after the transfer, using Raman spectroscopy and imaging as well as optical and atomic force microscopy techniques. This simple transfer method is scalable and can lead to complete transfer of graphene onto flexible and transparent polymer support films without affecting the quality of the graphene during the transfer procedure.

  5. mwnts composite film modified glassy carbon electrode

    African Journals Online (AJOL)

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    ABSTRACT: A poly p-aminosalicylic acid (Poly(p-ASA)) and multiwall carbon nanotubes. (MWCNTs) composite modified glassy carbon (GC) electrode was constructed by casting the MWNTs on the GC electrode surface followed by electropolymerization of the p-ASA on the MWCNTs/GCE. The electrochemical behaviours ...

  6. Chemical composition of leaf extracts of Stevia rebaudiana Bertoni grown experimentally in Vojvodina

    Directory of Open Access Journals (Sweden)

    IVANA S. MARKOVIC

    2008-03-01

    Full Text Available The chemical composition of leaf extracts of Stevia rebaudiana Bertoni, grown for the first time on an experimental field near Zrenjanin, was examined by GC–MS. The tested plant material was harvested in September of 2002. To analyze the chemical composition of the lipophilic components of the plant leaves, essential oils and ethyl acetate extract were isolated. Qualitative analysis of the essential oil obtained by hydrodistillation showed that among the identified 88 compounds, the majority were mono- and sesquiterpenes (50 types identified. By analysing the ethyl acetate extract, the presence of fatty acids (present as free and as esters, n-alkanes, n-alkenes, cyclic alkanes, alcohols, aldehydes, ketones, etc. was ascertained. Sesquiterpenes prevailed among the terpenes (50 types identified. Further constituents identified in ethyl acetate extract included sterols. Nerol, b-cyclocitral, safranal, aromadendrene, a-amorphene and T-muurolol were identified for the first time in this species, with match values over 90 %. Taking into consideration that these terpenes were identified for the first time in this species, it is obvious that Stevia rebaudiana grown in this area possesses certain specific characteristics that can be ascribed to cultivation on a domestic plantation.

  7. Defects, strain relaxation, and compositional grading in high indium content InGaN epilayers grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Bazioti, C.; Kehagias, Th.; Pavlidou, E.; Komninou, Ph.; Karakostas, Th.; Dimitrakopulos, G. P., E-mail: gdim@auth.gr [Physics Department, Aristotle University of Thessaloniki, GR 541 24 Thessaloniki (Greece); Papadomanolaki, E.; Iliopoulos, E. [Microelectronics Research Group (MRG), IESL, FORTH, P.O. Box 1385, 71110 Heraklion Crete, Greece and Physics Department, University of Crete, Heraklion Crete (Greece); Walther, T. [Department of Electronic & Electrical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Smalc-Koziorowska, J. [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw (Poland)

    2015-10-21

    We investigate the structural properties of a series of high alloy content InGaN epilayers grown by plasma-assisted molecular beam epitaxy, employing the deposition temperature as variable under invariant element fluxes. Using transmission electron microscopy methods, distinct strain relaxation modes were observed, depending on the indium content attained through temperature adjustment. At lower indium contents, strain relaxation by V-pit formation dominated, with concurrent formation of an indium-rich interfacial zone. With increasing indium content, this mechanism was gradually substituted by the introduction of a self-formed strained interfacial InGaN layer of lower indium content, as well as multiple intrinsic basal stacking faults and threading dislocations in the rest of the film. We show that this interfacial layer is not chemically abrupt and that major plastic strain relaxation through defect introduction commences upon reaching a critical indium concentration as a result of compositional pulling. Upon further increase of the indium content, this relaxation mode was again gradually succeeded by the increase in the density of misfit dislocations at the InGaN/GaN interface, leading eventually to the suppression of the strained InGaN layer and basal stacking faults.

  8. Structure disorder degree of polysilicon thin films grown by different processing: Constant C from Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Quan, E-mail: wangq@mail.ujs.edu.cn [School of mechanical engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhang, Yanmin; Hu, Ran; Ren, Naifei [School of mechanical engineering, Jiangsu University, Zhenjiang 212013 (China); Ge, Daohan [School of mechanical engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2013-11-14

    Flat, low-stress, boron-doped polysilicon thin films were prepared on single crystalline silicon substrates by low pressure chemical vapor deposition. It was found that the polysilicon films with different deposition processing have different microstructure properties. The confinement effect, tensile stresses, defects, and the Fano effect all have a great influence on the line shape of Raman scattering peak. But the effect results are different. The microstructure and the surface layer are two important mechanisms dominating the internal stress in three types of polysilicon thin films. For low-stress polysilicon thin film, the tensile stresses are mainly due to the change of microstructure after thermal annealing. But the tensile stresses in flat polysilicon thin film are induced by the silicon carbide layer at surface. After the thin film doped with boron atoms, the phenomenon of the tensile stresses increasing can be explained by the change of microstructure and the increase in the content of silicon carbide. We also investigated the disorder degree states for three polysilicon thin films by analyzing a constant C. It was found that the disorder degree of low-stress polysilicon thin film larger than that of flat and boron-doped polysilicon thin films due to the phase transformation after annealing. After the flat polysilicon thin film doped with boron atoms, there is no obvious change in the disorder degree and the disorder degree in some regions even decreases.

  9. Nanostructured and wide bandgap CdS:O thin films grown by reactive RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M. A.; Rahman, K. S.; Haque, F.; Rashid, M. J.; Akhtaruzzaman, M.; Sopian, K.; Sulaiman, Y. [Solar Energy Research Institute (SERI), National University of Malaysia, 43600 Bangi (Malaysia); Amin, N. [Solar Energy Research Institute (SERI), National University of Malaysia, 43600 Bangi (Malaysia); Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, National University of Malaysia, 43600 Bangi (Malaysia)

    2015-05-15

    In this study, CdS:O thin films were prepared from a 99.999% CdS target by reactive sputtering in a Ar:O{sub 2} (99:1) ambient with different RF power at room temperature. The deposited films were studied by means of XRD, SEM, EDX, Hall Effect and UV-Vis spectrometry. The incorporations of O{sub 2} into the films were observed to increase with the decrease of deposition power. The cryatallinity of the films were reduced, whereas the band gaps of the films were increased by the increase of O{sub 2} content on the films. The films were found in nano-structured grains with a compact surface. It has been seen that the highest carrier density is observed in the film with O{sub 2} at.% 21.10, while the values decreased with the further increase or decrease of O{sub 2} content on the films; indicating that specific amount of donor like O{sub 2} atoms substitute to the S atoms can improve the carrier density of the CdS:O thin film.

  10. Phase transformation of nanostructured titanium dioxide thin films grown by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Soenmezoglu, Savas [Karamanoglu Mehmetbey University, Faculty of Kamil Ozdag Science, Department of Physics, Karaman (Turkey); Cankaya, Gueven [Yildirim Beyazit University, Faculty of Engineering and Natural Sciences, Materials Engineering, Ankara (Turkey); Serin, Necmi [Ankara University, Faculty of Engineering, Department of Physics Engineering, Ankara (Turkey)

    2012-04-15

    Nanostructured TiO{sub 2} thin films were deposited on quartz glass at room temperature by sol-gel dip coating method. The effects of annealing temperature between 200 C to 1100 C were investigated on the structural, morphological, and optical properties of these films. The X-ray diffraction results showed that nanostructured TiO{sub 2} thin film annealed at between 200 C to 600 C was amorphous transformed into the anatase phase at 700 {sup circle} C, and further into rutile phase at 1000 C. The crystallite size of TiO{sub 2} thin films was increased with increasing annealing temperature. From atomic force microscopy images it was confirmed that the microstructure of annealed thin films changed from column to nubbly. Besides, surface roughness of the thin films increases from 1.82 to 5.20 nm, and at the same time, average grain size as well grows up from about 39 to 313 nm with increase of the annealing temperature. The transmittance of the thin films annealed at 1000 and 1100 C was reduced significantly in the wavelength range of about 300-700 nm due to the change of crystallite phase. Refractive index and optical high dielectric constant of the n-TiO{sub 2} thin films were increased with increasing annealing temperature, and the film thickness and the optical band gap of nanostructured TiO{sub 2} thin films were decreased. (orig.)

  11. Fractal features of CdTe thin films grown by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hosseinpanahi, Fayegh, E-mail: f.hosseinpanahi@yahoo.com [Department of Physics, Payame Noor University, P.O. Box 19395-4697, Tehran (Iran, Islamic Republic of); Raoufi, Davood [Department of Physics, University of Bu Ali Sina, P.O. Box 65174, Hamedan (Iran, Islamic Republic of); Ranjbarghanei, Khadijeh [Department of Physics, Plasma Physics Research Center, Science & Research Branch Islamic Azad University, Tehran (Iran, Islamic Republic of); Karimi, Bayan [Department of Physics, Payame Noor University, P.O. Box 19395-4697, Tehran (Iran, Islamic Republic of); Babaei, Reza [Department of Physics, Plasma Physics Research Center, Science & Research Branch Islamic Azad University, Tehran (Iran, Islamic Republic of); Hasani, Ebrahim [Department of Physics, University of Bu Ali Sina, P.O. Box 65174, Hamedan (Iran, Islamic Republic of)

    2015-12-01

    Graphical abstract: - Highlights: • CdTe thin films were deposited on glass substrates by RF magnetron sputtering at room temperature with different deposition time 5, 10 and 15 min. • Nanostructure of CdTe layer indicates that CdTe films are polycrystalline and have zinc blende structure, irrespective of their deposition time. • Complexity and roughness of the CdTe films and strength of multifractality increase with increasing deposition time. • Detrended fluctuation analysis (DFA) and also multifractal detrended fluctuation analysis (MFDFA) methods showed that prepared CdTe films have multifractal nature. - Abstract: Cadmium telluride (CdTe) thin films were prepared by RF magnetron sputtering on glass substrates at room temperature (RT). The film deposition was performed for 5, 10, and 15 min at power of 30 W with a frequency of 13.56 MHz. The crystal structure of the prepared CdTe thin films was studied by X-ray diffraction (XRD) technique. XRD analyses indicate that the CdTe films are polycrystalline, having zinc blende structure of CdTe irrespective of their deposition time. All CdTe films showed a preferred orientation along (1 1 1) crystalline plane. The surface morphology characterization of the films was studied using atomic force microscopy (AFM). The quantitative AFM characterization shows that the RMS surface roughness of the prepared CdTe thin films increases with increasing the deposition time. The detrended fluctuation analysis (DFA) and also multifractal detrended fluctuation analysis (MFDFA) methods showed that prepared CdTe thin films have multifractal nature. The complexity, roughness of the CdTe thin films and strength of the multifractality increase as deposition time increases.

  12. Optical and structural properties of ZnO nanorods grown on graphene oxide and reduced graphene oxide film by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Alver, U., E-mail: alver@ksu.edu.tr [Department of Physics, Kahramanmaras Sutcu Imam University, K. Maras 46100 (Turkey); Zhou, W.; Belay, A.B. [Nanoscience and Technology Center, University of Central Florida, Orlando, FL 32816 (United States); Florida Solar Energy Center, Cocoa, FL 32922 (United States); Krueger, R. [Nanoscience and Technology Center, University of Central Florida, Orlando, FL 32816 (United States); Davis, K.O.; Hickman, N.S. [Nanoscience and Technology Center, University of Central Florida, Orlando, FL 32816 (United States); Florida Solar Energy Center, Cocoa, FL 32922 (United States)

    2012-01-15

    ZnO nanorods were grown on graphene oxide (GO) and reduced graphene oxide (RGO) films with seed layers by using simple hydrothermal method. The GO films were deposited by spray coating and then annealed at 400 Degree-Sign C in argon atmosphere to obtain RGO films. The optical and structural properties of the ZnO nanorods were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet-visible spectroscopy. The XRD patterns and SEM images show that without a seed layer, no ZnO nanorod deposition occurs on GO or RGO films. Transmittance of ZnO nanorods grown on RGO films was measured to be approximately 83% at 550 nm. Furthermore, while transmittance of RGO films increases with ZnO nanorod deposition, transmittance of GO decreases.

  13. REGULATED DEGRADABILITY OF COMPOSITE BIOBASED FILMS

    Directory of Open Access Journals (Sweden)

    Volodymyr M. Isaenko

    2008-02-01

    Full Text Available  Degradable biobased (derived from agriculture composites are emerging materials that offer benefits to the environment thus minimizing waste that would be otherwise deposited in landfills. Single-use primary packaging materials have been identified as suitable items to be replaced by biodegradable materials from renewable resources. Materials composed of starch, soy protein and polyvinylalcohol, modified by hydrophobic fatty acids, are evaluated in terms of water resistance as promising substitutes for packaging materials.

  14. Polyester fabric coated with Ag/ZnO composite film by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Xiaohong, E-mail: yxhong1981_2004@126.com [Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, Jiangsu (China); Faculty of Clothing and Design, Minjiang University, Fuzhou 350121, Fujian (China); Xu, Wenzheng, E-mail: xwz8199@126.com [Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, Jiangsu (China); Huang, Fenglin, E-mail: windhuang325@163.com [Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, Jiangsu (China); Chen, Dongsheng, E-mail: mjuchen@126.com [Faculty of Clothing and Design, Minjiang University, Fuzhou 350121, Fujian (China); Wei, Qufu, E-mail: qfwei@jiangnan.edu.cn [Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, Jiangsu (China)

    2016-12-30

    Highlights: • Ag/ZnO composite film was successfully deposited on polyester fabric by magnetron sputtering technique. • Ag film was easily oxidized into Ag{sub 2}O film in high vacuum oxygen environment. • The zinc film coated on the surface of Ag film before RF reactive sputtering could protect the silver film from oxidation. • Polyester fabric coated with Ag/ZnO composite film can obtained structural color. • The anti-ultraviolet and antistatic properties of polyester fabric coated with Ag/ZnO composite film all were good. - Abstract: Ag/ZnO composite film was successfully deposited on polyester fabric by using direct current (DC) magnetron sputtering and radio frequency (RF) magnetron reaction sputtering techniques with pure silver (Ag) and zinc (Zn) targets. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to examine the deposited film on the fabric. It was found that the zinc film coated on Ag film before RF reactive sputtering could protect the silver film from oxidation. Anti-ultraviolet property and antistatic property of the coated samples using different magnetron sputtering methods were also investigated. The experimental results showed that Ag film was oxidized into in Ag{sub 2}O film in high vacuum oxygen environment. The deposition of Zn film on the surface of the fabric coated with Ag film before RF reactive sputtering, could successfully obtained Ag/ZnO composite film, and also generated structural color on the polyester fabric.

  15. Elastically strained and relaxed La0.67Ca0.33MnO3 films grown on lanthanum aluminate substrates with different orientations

    Science.gov (United States)

    Boikov, Yu. A.; Serenkov, I. T.; Sakharov, V. I.; Claeson, T.

    2016-12-01

    Structure of 40-nm thick La0.67Ca0.33MnO3 (LCMO) films grown by laser evaporation on (001) and (110) LaAlO3 (LAO) substrates has been investigated using the methods of medium-energy ion scattering and X-ray diffraction. The grown manganite layers are under lateral biaxial compressive mechanical stresses. When (110)LAO wafers are used as the substrates, stresses relax to a great extent; the relaxation is accompanied by the formation of defects in a (3-4)-nm thick manganite-film interlayer adjacent to the LCMO-(110)LAO interface. When studying the structure of the grown layers, their electro- and magnetotransport parameters have been measured. The electroresistance of the LCMO films grown on the substrates of both types reached a maximum at temperature T M of about 250 K. At temperatures close to T M magnetoresistance of the LCMO/(110)LAO films exceeds that of the LCMO/(001)LAO films by 20-30%; however, the situation is inverse at low temperatures ( T < 150 K). At T < T M , the magnetotransport in the grown manganite films significantly depends on the spin ordering in ferromagnetic domains, which increase with a decrease in temperature.

  16. Optical properties and secondary phase identification in PLD-grown Cu2ZnSnS4 for thin-film photovoltaics

    DEFF Research Database (Denmark)

    Crovetto, Andrea; Cazzaniga, Andrea Carlo; Ettlinger, Rebecca Bolt

    2014-01-01

    in CZTS films grown by pulsed laser deposition (PLD) for a range of laser energies and substrate temperatures. Film properties, such as absorption coefficient, refraction index and thickness are extracted from ellipsometry measurements. The same set of properties is evaluated for chemical......) and profiling. Identification of secondary phases in CZTS films under different PLD process parameters and their effect on optical constants is an important factor in optimizing the deposition process for production of high-efficiency CZTS solar cells....

  17. Aluminum-doped zinc oxide thin films grown on various substrates using facing target sputtering system

    Science.gov (United States)

    Kim, Hwa-Min; Lee, Chang Hyun; Shon, Sun Young; Kim, Bong Hwan

    2017-11-01

    Aluminum-doped zinc oxide (AZO) films were fabricated on various substrates, such as glass, polyethylene naphthalate (PEN), and polyethylene terephthalate (PET), at room temperature using a facing target sputtering (FTS) system with hetero ZnO and Al2O3 targets, and their electrical and optical properties were investigated. The AZO film on glass exhibited compressive stress while the films on the plastic substrates showed tensile stress. These stresses negatively affected the crystalline quality of the AZO films, and it is suggested that the poor crystalline quality of the films may be related to the neutral Al-based defect complexes formed in the films; these complexes act as neutral impurity scattering centers. AZO films with good optoelectronic properties could be formed on the glass and plastic substrates by the FTS technique using the hetero targets. The AZO films deposited on the glass, PEN, and PET substrates showed very low resistivities, of 5.0 × 10-4 Ω cm, 7.0 × 10-4 Ω cm, and 7.4 × 10-4 Ω cm, respectively. Further, the figure merit of the AZO film formed on the PEN substrate in the visible range (400-700 nm) was significantly higher than that of the AZO film on PET and similar to that of the AZO film on glass. Finally, the average transmittances of the films in the visible range (400-700 nm) were 83.16% (on glass), 76.3% (on PEN), and 78.16% (on PET).

  18. Electron traps as major recombination centers in n-GaN films grown by metalorganic chemical vapor deposition

    Science.gov (United States)

    Lee, In-Hwan; Polyakov, Alexander Y.; Smirnov, Nikolai B.; Yakimov, Eugene B.; Tarelkin, Sergey A.; Turutin, Andery V.; Shemerov, Ivan V.; Pearton, Stephen J.

    2016-06-01

    For a group of n-GaN films grown by metalorganic chemical vapor deposition (MOCVD) using both straight MOCVD and epitaxial lateral overgrowth techniques (ELOG proper or pendeo overgrowth), the spectra of deep traps were measured by deep-level transient spectroscopy (DLTS) with electrical or optical injection (ODLTS). The results were compared with diffusion length measurement results obtained from electron-beam-induced current experiments. The results strongly indicate that deep electron traps near E c - 0.56 eV could be the major recombination centers determining the diffusion length values in pendeo samples.

  19. Thin films of copper oxide and copper grown by atomic layer deposition for applications in metallization systems of microelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Waechtler, Thomas

    2010-05-25

    Copper-based multi-level metallization systems in today's ultralarge-scale integrated electronic circuits require the fabrication of diffusion barriers and conductive seed layers for the electrochemical metal deposition. Such films of only several nanometers in thickness have to be deposited void-free and conformal in patterned dielectrics. The envisaged further reduction of the geometric dimensions of the interconnect system calls for coating techniques that circumvent the drawbacks of the well-established physical vapor deposition. The atomic layer deposition method (ALD) allows depositing films on the nanometer scale conformally both on three-dimensional objects as well as on large-area substrates. The present work therefore is concerned with the development of an ALD process to grow copper oxide films based on the metal-organic precursor bis(trin- butylphosphane)copper(I)acetylacetonate [({sup n}Bu{sub 3}P){sub 2}Cu(acac)]. This liquid, non-fluorinated {beta}-diketonate is brought to react with a mixture of water vapor and oxygen at temperatures from 100 to 160 C. Typical ALD-like growth behavior arises between 100 and 130 C, depending on the respective substrate used. On tantalum nitride and silicon dioxide substrates, smooth films and selfsaturating film growth, typical for ALD, are obtained. On ruthenium substrates, positive deposition results are obtained as well. However, a considerable intermixing of the ALD copper oxide with the underlying films takes place. Tantalum substrates lead to a fast self-decomposition of the copper precursor. As a consequence, isolated nuclei or larger particles are always obtained together with continuous films. The copper oxide films grown by ALD can be reduced to copper by vapor-phase processes. If formic acid is used as the reducing agent, these processes can already be carried out at similar temperatures as the ALD, so that agglomeration of the films is largely avoided. Also for an integration with subsequent

  20. Antimony segregation and n-type doping in Si/Si(111) films grown by molecular beam epitaxy

    Science.gov (United States)

    Yurasov, D. V.; Drozdov, M. N.; Schmagin, V. B.; Yunin, P. A.; Novikov, A. V.

    2017-10-01

    The temperature dependence of antimony segregation in Si/Si(111) films grown by molecular-beam epitaxy was investigated experimentally. The obtained results were found to be qualitatively similar to the previously reported data for Si(001) case, but rather significant quantitative differences were observed. It was obtained that segregation ratio, which is defined as surface-to-bulk impurity concentration ratio, varies by nearly 5 orders of magnitude in the relatively narrow temperature interval of 500-675 °C for Si(111). This finding allowed to disseminate the previously proposed technique of selective doping of Si(001) to the Si(111) case. Using this technique selectively n-type doped Si films were fabricated which have abrupt boundaries of the antimony concentration profiles. A profile abruptness as low as 1.5 nm/decade was obtained.

  1. 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.)

  2. Post deposition annealing of epitaxial Ce(1-x)Pr(x)O(2-δ) films grown on Si(111).

    Science.gov (United States)

    Wilkens, H; Spiess, W; Zoellner, M H; Niu, G; Schroeder, T; Wollschläger, J

    2015-04-21

    In this work the structural and morphological changes of Ce1-xPrxO2-δ (x = 0.20, 0.35 and 0.75) films grown on Si(111) due to post deposition annealing are investigated by low energy electron diffraction combined with a spot profile analysis. The surface of the oxide films exhibit mosaics with large terraces separated by monoatomic steps. It is shown that the Ce/Pr ratio and post deposition annealing temperature can be used to tune the mosaic spread, terrace size and step height of the grains. The morphological changes are accompanied by a phase transition from a fluorite type lattice to a bixbyite structure. Furthermore, at high PDA temperatures a silicate formation via a polycrystalline intermediate state is observed.

  3. Improvement of thermoelectric properties of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} films grown on graphene substrate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Wan [Thin Film Materials Research Group, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); School of Electrical and Electronic Engineering, Yonsei University, Seoul (Korea, Republic of); Kim, Gun Hwan; Choi, Ji Woon; An, Ki-Seok; Lee, Young Kuk [Thin Film Materials Research Group, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Kim, Jin-Sang [Center for Electronic Materials, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Kim, Hyungjun [School of Electrical and Electronic Engineering, Yonsei University, Seoul (Korea, Republic of)

    2017-06-15

    A study of substrate effect on the thermoelectric (TE) properties of Bi{sub 2}Te{sub 3} (BT) and Sb{sub 2}Te{sub 3} (ST) thin films grown by plasma-enhanced chemical vapor deposition (PECVD) was performed. Graphene substrates which have small lattice mismatch with BT and ST were used for the preparation of highly oriented BT and ST thin films. Carrier mobility of the epitaxial BT and ST films grown on the graphene substrates increased as the deposition temperature increased, which was not observed in that of SiO{sub 2}/Si substrates. Seebeck coefficients of the as-grown BT and ST films were observed to be maintained even though carrier concentration increased in the epitaxial BT and ST films on graphene substrate. Although Seebeck coefficient was not improved, power factor of the as-grown BT and ST films was considerably enhanced due to the increase of electrical conductivity resulting from the high carrier mobility and moderate carrier concentration in the epitaxial BT and ST films. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. High Performance Thin-Film Composite Forward Osmosis Membrane

    KAUST Repository

    Yip, Ngai Yin

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 μm) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m2-h-1, while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution. © 2010 American Chemical Society.

  5. Structural and biological properties of carbon nanotube composite films

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Roger J. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)]. E-mail: roger.narayan@mse.gatech.edu; Berry, C.J. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States); Brigmon, R.L. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States)

    2005-11-20

    Carbon nanotube composite films have been developed that exhibit unusual structural and biological properties. These novel materials have been created by pulsed laser ablation of graphite and bombardment of nitrogen ions at temperatures between 600 and 700 deg. C. High-resolution transmission electron microscopy and radial distribution function analysis demonstrate that this material consists of sp{sup 2}-bonded concentric ribbons that are wrapped approximately 15 deg. normal to the silicon substrate. The interlayer order in this material extends to approximately 15-30 A. X-ray photoelectron spectroscopy and Raman spectroscopy data suggest that this material is predominantly trigonally coordinated. The carbon nanotube composite structure results from the use of energetic ions, which allow for non-equilibrium growth of graphitic planes. In vitro testing has revealed significant antimicrobial activity of carbon nanotube composite films against Staphylococcus aureus and Staphylococcus warneri colonization. Carbon nanotube composite films may be useful for inhibiting microorganism attachment and biofilm formation in hemodialysis catheters and other medical devices.

  6. Influence of annealing temperature on ZnO thin films grown by dual ...

    Indian Academy of Sciences (India)

    Administrator

    X-ray diffraction (XRD) measurements showed that all ZnO films have (002) preferred orientation. Full-width at half-maximum (FWHM) of XRD from the (002) crystal plane was observed to reach to a minimum value of 0⋅139° from ZnO film, annealed at 600 °C. Photoluminescence (PL) measurements demonstrated sharp ...

  7. Electrical characterization of gadolinia doped ceria films grown by pulsed laser deposition

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Heiroth, Sebastian; Lundberg, Mats

    2010-01-01

    Electrical characterization of 10 mol% gadolinia doped ceria (CGO10) films of different thicknesses prepared on MgO(100) substrates by pulsed laser deposition is presented. Dense, polycrystalline and textured films characterized by fine grains (grain sizes ... film, respectively) are obtained in the deposition process. Grain growth is observed under thermal cycling between 300 and 800°C, as indicated by X-ray-based grain-size analysis. However, the conductivity is insensitive to this microstructural evolution but is found to be dependent on the sample...... values of 1.06 and 0.80 eV are obtained for the 20-nm film and the 435-nm film, respectively. The study shows that the ionic conductivity prevails in a broad range of oxygen partial pressures, for example down to about 10 −26 atm at 500°C....

  8. Study of structural and optical properties of ZnO films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lemlikchi, S., E-mail: lemlikchi_safo@yahoo.fr [Advanced Technology Development Centre, Cite 20 Aout 1956 BP 17 Baba Hassen, Algiers (Algeria); Abdelli-Messaci, S.; Lafane, S.; Kerdja, T. [Advanced Technology Development Centre, Cite 20 Aout 1956 BP 17 Baba Hassen, Algiers (Algeria); Guittoum, A.; Saad, M. [Nuclear Research Centre of Algiers, 2 Bd Frantz-Fanon, Algiers (Algeria)

    2010-07-01

    Wurtzite zinc oxides films (ZnO) were deposited on silicon (0 0 1) and corning glass substrates using the pulsed laser deposition technique. The laser fluence, target-substrate distance, substrate temperature of 300 deg. C were fixed while varying oxygen pressures from 2 to 500 Pa were used. It is observed that the structural properties of ZnO films depend strongly on the oxygen pressure and the substrate nature. The film crystallinity improves with decreasing oxygen pressure. At high oxygen pressure, the films are randomly oriented, whereas, at low oxygen pressures they are well oriented along [0 0 1] axis for Si substrates and along [1 0 3] axis for glass substrates. A honeycomb structure is obtained at low oxygen pressures, whereas microcrystalline structures were obtained at high oxygen pressures. The effect of oxygen pressure on film transparency, band gap E{sub g} and Urbach energies was investigated.

  9. Luminescent and scintillation properties of CsI:Tl films grown by the liquid phase epitaxy method

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Yu. [Laboratory of Optoelectronic Materials (LOM), Electronics Department of Ivan Franko National University of Lviv, 107 Gen. Tarnawskogo Str., 70017 Lviv (Ukraine); Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85-090 Bydgoszcz (Poland); Voznyak, T.; Turchak, R. [Laboratory of Optoelectronic Materials (LOM), Electronics Department of Ivan Franko National University of Lviv, 107 Gen. Tarnawskogo Str., 70017 Lviv (Ukraine); Fedorov, A. [Institute for Scintillation Materials of NAS of Ukraine, 60 Lenina Ave., 61001 Kharkiv (Ukraine); Wiesniewski, K.; Grinberg, M. [Institute of Experimental Physics of Gdansk University, 57 Wita Stwoza, 80-952 Gdansk (Poland)

    2010-10-15

    CsI:Tl films have been crystallized by the liquid phase epitaxy (LPE) method from CsI:Tl (0.3 mol.%) crystalline salt onto CsI substrates. The luminescent and scintillation properties of CsI:Tl films are systematically compared with the corresponding properties of CsI:Tl (0.3 and 0.03%) crystals grown from the melt. The luminescence of CsI:Tl films and CsI:Tl (0.03%) crystals in the bands peaked at 2.52 and 2.22 eV is related to the radiative relaxation from the weak-off and strong-off configurations of excitons localized around Tl{sup +} ions, respectively. Apart from single Tl{sup +} centers, in highly doped CsI:Tl (0.3%) crystals creation of Tl{sup +} dimer centers occurs. These centers form the additional emission bands peaked at 2.42 and 1.98 eV related to the weak-off and strong-off configurations of excitons localized around Tl{sup +} dimer centers. We found that the dominant mechanism of excitation of the strong-off luminescence of localized excitons in CsI:Tl films and crystals is the charge-transfer transition between I{sup -} anions and Tl{sup +} ions in single and dimer centers. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  10. Red emission from Eu-doped GaN luminescent films grown by metalorganic chemical vapor deposition

    Science.gov (United States)

    Pan, M.; Steckl, A. J.

    2003-07-01

    Bright red emission has been obtained at room temperature from Eu-doped GaN films pumped by 325 nm HeCd laser. The luminescent films were grown by metalorganic chemical vapor deposition on GaN/Al2O3 substrates. Trimethylgallium (TMGa), ammonia (NH3), and europium 2,2,4,4-tetramethyl-3,5-heptanedionate were used as sources for Ga, N, and Eu dopant, respectively. The influence of the V/III ratio during growth on the photoluminescence (PL) intensity has been studied using a fixed TMGa flow rate of 92 μmol/min and varying the NH3 flow rate. The film growth rate (˜2 μm/h) is nearly constant with V/III ratio over the range from ˜30 to ˜1000. The Eu incorporation in GaN films was found to decrease with increasing V/III ratio. The Eu PL intensity (normalized to the Eu concentration) exhibited a maximum at a V/III ratio of ˜100.

  11. Initial Metallization and Transition Metal Diffusion in ZnO Single Crystals, CVD-Grown Films, and Nanostructures

    Science.gov (United States)

    Katalinic, Senia; Rangan, Sylvie; Gateau, Rodney; Wu, Pan; Lu, Yicheng; Bartynski, Robert

    2008-03-01

    Transition metal doped ZnO is a promising candidate room temperature dilute magnetic semiconductor for spintronic applications. In previous studies indicate Fe or Mn dopants exhibit significantly different diffusion properties in ZnO. To explore whether this is an inherent property of ZnO or if it is related to non-ideal aspects of the films or nanostructures, we have studied the initial stages of Mn, Fe, and Cu metallization of the single crystal ZnO(0001)[Zn-terminated] and (11-20) surfaces, as well as MOCVD-grown epitaxial a-plane films using scanning tunneling microscopy and spectroscopy (STM and STS). While deposited Cu forms well defined islands, all three surfaces exhibit substantial disruption upon Fe deposition, including significant change in terrace widths and a markedly smaller fraction of atomic height steps. Upon annealing, Cu islands become mobile and coarsen, but the underlying ZnO structure is not strongly affected. Annealing with Fe on the surface, significant coarsening and roughening of the substrate occurs even at the modest annealing temperature of 200C, and this effect is enhanced upon annealing to 400 C. Initial results suggest that uptake of metals into the epi-film is predominantly determined by the properties of the (11-20) surface that terminates the film.

  12. Self Focusing SIMS: Probing thin film composition in very confined volumes

    Energy Technology Data Exchange (ETDEWEB)

    Franquet, Alexis, E-mail: alexis.franquet@imec.be [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Douhard, Bastien [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Melkonyan, Davit [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Instituut voor Kern- en Stralingsfysica, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Favia, Paola; Conard, Thierry [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Vandervorst, Wilfried [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Instituut voor Kern- en Stralingsfysica, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)

    2016-03-01

    Graphical abstract: - Highlights: • SiGe layers were grown in trenches of various widths (down to 20 nm) on Si substrate and surrounded by SiO{sub 2} films. • Standard SIMS analysis to probe the composition in narrow trenches fails at dimensions less than a micron. • Self Focusing SIMS able to probe thin film composition in very confined volumes (dimension < 20 nm). - Abstract: The continued downscaling of micro and nanoelectronics devices has increased the importance of novel materials and their interfaces very strongly thereby necessitating the availability of adequate metrology and very tight process control as well. For instance, the introduction of materials like SiGe or III-V compounds leads to the need for the determination of the exact composition and thickness of the resulting thin films. Concurrent with this trend, one is faced with layer growth concepts such as aspect ratio trapping, which exploit the reduced dimensionality of the devices. As this leads to films with very different characteristics as compared to their blanket counterparts, characterization now has to be performed on thin films grown in very confined volumes (with dimensions ranging down to less than 10–20 nm) and standard analysis methods like X-Ray Photoelectron Spectroscopy, Secondary Ion Mass Spectrometry (SIMS) and Rutherford Backscattering Spectrometry, no longer seem applicable due to a lack of spatial resolution. On the other hand, techniques with appropriate spatial resolution like Atom Probe Tomography or Transmission Electron Microscopy are time consuming and suffer from a lack of sensitivity due to their highly localized analysis volume. In this paper, a novel concept termed Self Focusing SIMS, is presented which overcomes the spatial resolution limitations of SIMS without sacrificing the sensitivity. The concept is based on determining the composition of a specific compound using cluster ions which contain the constituents of the compound. Their formation mechanism

  13. Optimization of synthesis conditions of PbS thin films grown by chemical bath deposition using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Yücel, Ersin, E-mail: dr.ersinyucel@gmail.com [Department of Physics, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey); Yücel, Yasin; Beleli, Buse [Department of Chemistry, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey)

    2015-09-05

    Highlights: • For the first time, RSM and CCD used for optimization of PbS thin film. • Tri-sodium citrate, deposition time and temperature were independent variables. • PbS thin film band gap value was 2.20 eV under the optimum conditions. • Quality of the film was improved after chemometrics optimization. - Abstract: In this study, PbS thin films were synthesized by chemical bath deposition (CBD) under different deposition parameters. Response surface methodology (RSM) was used to optimize synthesis parameters including amount of tri-sodium citrate (0.2–0.8 mL), deposition time (14–34 h) and deposition temperature (26.6–43.4 °C) for deposition of the films. 5-level-3-factor central composite design (CCD) was employed to evaluate effects of the deposition parameters on the response (optical band gap of the films). The significant level of both the main effects and the interaction are investigated by analysis of variance (ANOVA). The film structures were characterized by X-ray diffractometer (XRD). Morphological properties of the films were studied with a scanning electron microscopy (SEM). The optical properties of the films were investigated using a UV–visible spectrophotometer. The optimum amount of tri-sodium citrate, deposition time and deposition temperature were found to be 0.7 mL, 18.07 h and 30 °C respectively. Under these conditions, the experimental band gap of PbS was 2.20 eV, which is quite good correlation with value (1.98 eV) predicted by the model.

  14. Inflorescence and leaves essential oil composition of hydroponically grown Ocimum basilicum L

    Directory of Open Access Journals (Sweden)

    MOHAMMAD BAGHER HASSANPOURAGHDAM

    2010-10-01

    Full Text Available In order to characterize the essential oils of leaves and inflorescences, water distilled volatile oils of hydroponically grown Ocimum basilicum L. were analyzed by GC/EI-MS. Fifty components were identified in the inflorescence and leaf essential oils of the basil plants, accounting for 98.8 and 99.9 % of the total quantified components respectively. Phenylpropanoids (37.7 % for the inflorescence vs. 58.3 % for the leaves were the predominant class of oil constituents, followed by sesquiterpenes (33.3 vs. 19.4 % and monoterpenes (27.7 vs. 22.1 %. Of the monoterpenoid compounds, oxygenated monoterpenes (25.2 vs. 18.9 % were the main subclass. Sesquiterpene hydrocarbons (25 vs. 15.9 % were the main subclass of sesquiterpenoidal compounds. Methyl chavicol, a phenylpropane derivative, (37.2 vs. 56.7 % was the principle component of both organ oils, with up to 38 and 57 % of the total identified components of the inflorescence and leaf essential oils, respectively. Linalool (21.1 vs. 13.1 % was the second common major component followed by α-cadinol (6.1 vs. 3 %, germacrene D (6.1 vs. 2.7 % and 1,8-cineole (2.4 vs. 3.5 %. There were significant quantitative but very small qualitative differences between the two oils. In total, considering the previous reports, it seems that essential oil composition of hydroponically grown O. basilicum L. had volatile constituents comparable with field grown counterparts, probably with potential applicability in the pharmaceutical and food industries.

  15. Opto-Electronic Properties of Cu2ZnSnS4 Thin Films Grown by Ultrasonic Spray Pyrolysis

    Science.gov (United States)

    Deepa, K. G.; Sajeesh, T. H.; Jampana, Nagaraju

    2017-09-01

    Cu2ZnSnS4 (CZTS) films are deposited by ultrasonic spray pyrolysis technique for photovoltaic applications. The optoelectronic properties are studied by varying Zn and Sn compositions in the film. Films showed a tetragonal kesterite structure with preferential orientation along the (112) plane. The sample with the highest Cu concentration showed the lowest band gap of 1.46 eV. The grain size of the films is greater than 1 μm. Temperature-dependent conductivity studies revealed the presence of defects such as VCu, VS, VSn, CuZn, ZnCu, ZnSn and SnZn in the films. The sample with a Cu/(Zn + Sn) ratio of 0.75 showed Cu-poor and Zn-rich composition and better opto-electronic properties. The sample has p-type conductivity with a resistivity of 12 Ω cm. A [VCu-ZnCu] defect complex is identified in this sample along with a ZnSn acceptor level which is favorable for solar cells.

  16. Opto-Electronic Properties of Cu2ZnSnS4 Thin Films Grown by Ultrasonic Spray Pyrolysis

    Science.gov (United States)

    Deepa, K. G.; Sajeesh, T. H.; Jampana, Nagaraju

    2018-01-01

    Cu2ZnSnS4 (CZTS) films are deposited by ultrasonic spray pyrolysis technique for photovoltaic applications. The optoelectronic properties are studied by varying Zn and Sn compositions in the film. Films showed a tetragonal kesterite structure with preferential orientation along the (112) plane. The sample with the highest Cu concentration showed the lowest band gap of 1.46 eV. The grain size of the films is greater than 1 μm. Temperature-dependent conductivity studies revealed the presence of defects such as VCu, VS, VSn, CuZn, ZnCu, ZnSn and SnZn in the films. The sample with a Cu/(Zn + Sn) ratio of 0.75 showed Cu-poor and Zn-rich composition and better opto-electronic properties. The sample has p-type conductivity with a resistivity of 12 Ω cm. A [VCu-ZnCu] defect complex is identified in this sample along with a ZnSn acceptor level which is favorable for solar cells.

  17. ESTIMATION OF YIELD AND CHEMICAL COMPOSITION OF WINTER GARLIC GROWN FOR BUNCH-HARVEST

    Directory of Open Access Journals (Sweden)

    Ewa Rekowska

    2009-06-01

    Full Text Available The aim of study carried out in 2004-2005 was evaluation of covers effect (perforated fi lm and polypropylene nonwoven and disparate density of plants in the row (2. 4. 6. and 8 cm on yield and chemical composition of winter garlic grown for bunch-harvest. On average. it was found that covering plants with polypropylene stimulated the yield by 19.8% in comparison to open fi eld cultivation. Further. the covers also affected the height of plants. number of leaves and the mean mass of bulbs. Regarding tested chemical components. it was found that signifi cantly higher dry weight. L-ascorbic acid and total chlorophyll content had garlic leaves grown without covers. Increase of plant density in the row from 8 to 2 cm caused signifi cant enhancement of yield. However. signifi cantly higher unit mass of all plant (including the mass of bulb higher L-ascorbic and total sugar content showed garlic plants planted at 20×8 and 20×6 cm spacing.

  18. Thermo-electrical properties of composite semiconductor thin films composed of nanocrystalline graphene-vanadium oxides.

    Science.gov (United States)

    Jung, Hye-Mi; Um, Sukkee

    2014-12-01

    This paper presents an experimental comparative study involving the characterization of the thermo-electrical and structural properties of graphene-based vanadium oxide (graphene-VOx) composite thin films on insulating and conducting surfaces (i.e., fused quartz and acrylic resin-impregnated graphite) produced by a sol-gel process via dipping-pyrolysis. A combination of FE-SEM and XPS analyses revealed that the graphene-VOx composite thin films (coated onto fused quartz) exhibiting the microstructure of 2-graded nanowire arrays with a diameter of 40-80 nm were composed of graphene, a few residual oxygen-containing functional groups (i.e., C-O and C=O), and the VO2 Magnéli phase. The temperature-dependent electrical resistance measured on the as-deposited thin films clearly demonstrated that the graphene-VOx composite nanowire arrays thermally grown on fused quartz act as a semiconductor switch, with a transition temperature of 64.7 degrees C in the temperature range of -20 degrees C to 140 degrees C, resulting from the contributions of graphene and graphene oxides. In contrast, the graphene-VOx composite thin films deposited onto acrylic resin-impregnated graphite exhibit a superlinear semiconducting property of extremely low electrical resistance with negative temperature coefficients (i.e., approximately four orders of magnitude lower than that of the fused quartz), despite the similar microstructural and morphological characteristics. This difference is attributed to the synergistic effects of the paramagnetic metal feature of the tightly stacked nanowire arrays consisting of hexagonal V2O3 on the intrinsic electrical properties of the acrylic resin-impregnated graphite substrate, as revealed by FE-SEM, EDX, AFM, and XRD measurements. Although the thermo-sensitive electrical properties of the graphene-VOx composite thin films are very substrate specific, the applicability of graphene sheets can be considerably effective in the formation of highly planar arrays

  19. Characterization of ZnO thin films grown on different p-Si substrate elaborated by solgel spin-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chebil, W., E-mail: Chbil.widad@live.fr [Laboratoire Physico-chimie des Matériaux, Unité de Service Commun de Recherche “High resolution X-ray diffractometer”, Département de Physique, Université de Monastir, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Fouzri, A. [Laboratoire Physico-chimie des Matériaux, Unité de Service Commun de Recherche “High resolution X-ray diffractometer”, Département de Physique, Université de Monastir, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Institut Supérieur des Sciences Appliquées et de Technologie de Sousse, Université de Sousse (Tunisia); Fargi, A. [Laboratoire de Microélectronique et Instrumentation, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l’environnement, 5019 Monastir (Tunisia); Azeza, B.; Zaaboub, Z. [Laboratoire Micro-Optoélectroniques et Nanostructures, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l' environnement, 5019 Monastir (Tunisia); and others

    2015-10-15

    Highlights: • High quality ZnO thin films grown on different p-Si substrates were successful obtained by sol–gel process. • PL measurement revealed that ZnO thin film grown on porous Si has the better optical quality. • I–V characteristics for all heterojunctions exhibit successful diode formation. • The diode ZnO/PSi shows a better photovoltaic effect under illumination with a maximum {sub Voc} of 0.2 V. - Abstract: In this study, ZnO thin films are deposited by sol–gel technique on p-type crystalline silicon (Si) with [100] orientation, etched silicon and porous silicon. The structural analyses showed that the obtained thin films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented along the c-axis direction. Morphological study revealed the presence of rounded and facetted grains irregularly distributed on the surface of all samples. PL spectra at room temperature revealed that ZnO thin film grown on porous Si has a strong UV emission with low defects in the visible region comparing with ZnO grown on plat Si and etched Si surface. The heterojunction parameters were evaluated from the (I–V) under dark and illumination at room temperature. The ideality factor, barrier height and series resistance of heterojunction grown on different p-Si substrates are determined by using different methods. Best electrical properties are obtained for ZnO layer deposited on porous silicon.

  20. High electron mobility thin-film transistors based on Ga{sub 2}O{sub 3} grown by atmospheric ultrasonic spray pyrolysis at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Stuart R., E-mail: s.thomas09@imperial.ac.uk, E-mail: thomas.anthopoulos@imperial.ac.uk; Lin, Yen-Hung; Faber, Hendrik; Anthopoulos, Thomas D., E-mail: s.thomas09@imperial.ac.uk, E-mail: thomas.anthopoulos@imperial.ac.uk [Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2BW (United Kingdom); Adamopoulos, George [Department of Engineering, Engineering Building, Lancaster University, Bailrigg, Lancaster LA1 4YR (United Kingdom); Sygellou, Labrini [Institute of Chemical Engineering and High Temperature Processes (ICEHT), Foundation of Research and Technology Hellas (FORTH), Stadiou Strasse Platani, P.O. Box 1414, Patras GR-265 04 (Greece); Stratakis, Emmanuel [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Heraklion 71003 (Greece); Materials Science and Technology Department, University, of Crete, Heraklion 71003 (Greece); Pliatsikas, Nikos; Patsalas, Panos A. [Laboratory of Applied Physics, Department of Physics, Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece)

    2014-09-01

    We report on thin-film transistors based on Ga{sub 2}O{sub 3} films grown by ultrasonic spray pyrolysis in ambient atmosphere at 400–450 °C. The elemental, electronic, optical, morphological, structural, and electrical properties of the films and devices were investigated using a range of complementary characterisation techniques, whilst the effects of post deposition annealing at higher temperature (700 °C) were also investigated. Both as-grown and post-deposition annealed Ga{sub 2}O{sub 3} films are found to be slightly oxygen deficient, exceptionally smooth and exhibit a wide energy bandgap of ∼4.9 eV. Transistors based on as-deposited Ga{sub 2}O{sub 3} films show n-type conductivity with the maximum electron mobility of ∼2 cm{sup 2}/V s.

  1. ZnS thin films grown by atomic layer deposition on GaAs and HgCdTe substrates at very low temperature

    Science.gov (United States)

    Sun, C. H.; Zhang, P.; Zhang, T. N.; Chen, X.; Chen, Y. Y.; Ye, Z. H.

    2017-09-01

    ZnS films grown on GaAs and HgCdTe substrates by atomic layer deposition (ALD) under very low temperature were investigated in this work. ZnS films were grown under several temperatures lower than 140 °C. The properties of the films were investigated with high-resolution X-ray diffraction (HRXRD), scanning electron microscope (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The results showed the ZnS films were polycrystalline. The growth rate monotonically decreased with temperature, as well as the root mean square (r.m.s) roughness measured by AFM. XPS measurement revealed the films were stoichiometric in Zn and S.

  2. Properties of HfO2 and HfO2: Y films grown by atomic layer deposition in an advanced monocyclopentadienyl-based process

    Science.gov (United States)

    Tamm, A.; Kukli, K.; Niinistö, J.; Lu, J.; Ritala, M.; Leskelä, M.

    2010-02-01

    Uniform HfO2 and HfO2:Y (7-8 cat.% Y) thin films were grown from a novel cyclopentadienyl-alkylamido precursor CpHf(NMe2)3, (CpMe)3Y and O3 at 300 °C. HfO2:Y films possessed somewhat higher roughness, and crystallized upon annealing at 500 °C in the form of cubic or tetragonal polymorph, compared to monoclinic HfO2 films. HfO2:Y demonstrated lower capacitance equivalent oxide thickness compared to HfO2, although HfO2films occurred slightly better insulating. Higher capacitance required intense crystallization achieved in the films grown to thicknesses exceeding 6 nm.

  3. Properties of HfO{sub 2} and HfO{sub 2}: Y films grown by atomic layer deposition in an advanced monocyclopentadienyl-based process

    Energy Technology Data Exchange (ETDEWEB)

    Tamm, A; Kukli, K [University of Tartu, Inst. of Physics, Department Materials Science, Taehe 4, 51010 Tartu (Estonia); Niinistoe, J; Ritala, M; Leskelae, M [University of Helsinki, Department of Chemistry, PO Box 55, FI-00014 University Helsinki (Finland); Lu, J, E-mail: aile.tamm@ut.e [Uppsala University, Angstroem Microstructure Laboratory, Department of Engineering Sciences, Box 538, SE-75121 Uppsala (Sweden)

    2010-02-15

    Uniform HfO{sub 2} and HfO{sub 2}:Y (7-8 cat.% Y) thin films were grown from a novel cyclopentadienyl-alkylamido precursor CpHf(NMe{sub 2}){sub 3}, (CpMe){sub 3}Y and O{sub 3} at 300 deg. C. HfO{sub 2}:Y films possessed somewhat higher roughness, and crystallized upon annealing at 500 deg. C in the form of cubic or tetragonal polymorph, compared to monoclinic HfO{sub 2} films. HfO{sub 2}:Y demonstrated lower capacitance equivalent oxide thickness compared to HfO{sub 2}, although HfO{sub 2}films occurred slightly better insulating. Higher capacitance required intense crystallization achieved in the films grown to thicknesses exceeding 6 nm.

  4. Simulation, fabrication and characterization of ZnO based thin film transistors grown by radio frequency magnetron sputtering.

    Science.gov (United States)

    Singh, Shaivalini; Chakrabarti, P

    2012-03-01

    We report the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by radio frequency (RF) magnetron sputtering technique. The bottom gate type TFT, consists of a conventional thermally grown SiO2 as gate insulator onto p-type Si substrates. The X-ray diffraction patterns reveal that the ZnO films are preferentially orientated in the (002) plane, with the c-axis perpendicular to the substrate. A typical ZnO TFT fabricated by this method exhibits saturation field effect mobility of about 0.6134 cm2/V s, an on to off ratio of 102, an off current of 2.0 x 10(-7) A, and a threshold voltage of 3.1 V at room temperature. Simulation of this TFT is also carried out by using the commercial software modeling tool ATLAS from Silvaco-International. The simulated global characteristics of the device were compared and contrasted with those measured experimentally. The experimental results are in fairly good agreement with those obtained from simulation.

  5. Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Zervos, M., E-mail: zervos@ucy.ac.cy; Giapintzakis, J. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Mihailescu, C. N. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); National Institute for Laser, Plasma and Radiation Physics, Str. Atomistilor, P.O. Box MG-36, 077125 Magurele (Romania); Luculescu, C. R. [Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); National Institute for Laser, Plasma and Radiation Physics, Str. Atomistilor, P.O. Box MG-36, 077125 Magurele (Romania); Florini, N.; Komninou, Ph.; Kioseoglou, J. [Nanostructured Materials Microscopy Group (NMMG), Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Othonos, A. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Research Center of Ultrafast Science, Department of Physics, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus)

    2014-05-01

    Indium tin oxide nanowires were grown by the reaction of In and Sn with O{sub 2} at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In{sub 2}O{sub 3} nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO{sub 2} and suppression of In{sub 2}O{sub 3} permitting compositional and structural tuning from SnO{sub 2} to In{sub 2}O{sub 3} which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

  6. Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism

    Science.gov (United States)

    Zervos, M.; Mihailescu, C. N.; Giapintzakis, J.; Luculescu, C. R.; Florini, N.; Komninou, Ph.; Kioseoglou, J.; Othonos, A.

    2014-05-01

    Indium tin oxide nanowires were grown by the reaction of In and Sn with O2 at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In2O3 nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO2 and suppression of In2O3 permitting compositional and structural tuning from SnO2 to In2O3 which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

  7. Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism

    Directory of Open Access Journals (Sweden)

    M. Zervos

    2014-05-01

    Full Text Available Indium tin oxide nanowires were grown by the reaction of In and Sn with O2 at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001. We obtain Sn doped In2O3 nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO2 and suppression of In2O3 permitting compositional and structural tuning from SnO2 to In2O3 which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

  8. Biomass composition of a Candida pseudotropicalis new strain grown on crude sweet whey

    Energy Technology Data Exchange (ETDEWEB)

    Michel, A.; Poncet, S.; Jacob, F.; Perrier, J.

    1987-01-01

    A yeast strain isolated from whey and named Candida LY 496 was grown continuously on crude sweet whey. The obtained biomass had a crude protein content of 47%. The amino acid composition was determined by high performance liquid chromatography (h.p.l.c.). All essential amino acids were present and among them lysine was predominant (11.8%). The total nucleic acids of the biomass was 6.4%. Lipids represented 5% and the fatty acids 2% of the dry matter; 75% of the fatty acids were unsaturated, and linoleic acid constituted only 1% of the total fatty acids. Niacin and vitamin B2 were the most abundant vitamins of the B group. Therefore Candida LY 496 biomass could be incorporated in animal food intakes. (Refs. 23).

  9. Bismuth onion thin film in situ grown on silicon wafer synthesized through a hydrothermal approach

    Science.gov (United States)

    Zhao, Yue; Liu, Hong; Liu, Jin; Hu, Chenguo; Wang, Jiyang

    2010-10-01

    Bismuth onion structured nanospheres with the same structure as carbon onions have been synthesized and observed. The nanospheres were synthesized through a hydrothermal method using bismuth hydroxide and silicon wafer as reactants. By controlling the heating temperature, heating time, and the pressure, nanoscale bismuth spheres can be in situ synthesized on silicon wafer, and forms a bismuth onion film on the substrate. The electronic property of the films was investigated. A formation mechanism of the formation of bismuth onions and the onion film has been proposed on the basis of experimental observations.

  10. Morphological aspects of the friction of hot-filament-grown diamond thin films

    Science.gov (United States)

    Blau, Peter J.; Yust, Charles S.; Clausing, Robert E.

    Recent developments in chemical vapor deposition (CVD) technology have made it possible to produce thin diamond film on a variety of substrate materials. Diamond, having a very high hardness and low sliding friction coefficient, is a good candidate for tribological applications. Diamond films produced by a hot-filament CVD method often have irregular surfaces owning to the preferred growth mode of the crystals which form on the surface. This investigation using sapphire and bearing steel spherically tipped sliders demonstrated that the morphology of the diamond film surface produced friction coefficient up to ten times those observed in previous experiments which involved smooth diamond surfaces sliding against various solids in air.

  11. Nitrogen doping in atomic layer deposition grown titanium dioxide films by using ammonium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Kaeaeriaeinen, M.-L., E-mail: marja-leena.kaariainen@lut.fi; Cameron, D.C.

    2012-12-30

    Titanium dioxide films have been created by atomic layer deposition using titanium chloride as the metal source and a solution of ammonium hydroxide in water as oxidant. Ammonium hydroxide has been used as a source of nitrogen for doping and three thickness series have been deposited at 350 Degree-Sign C. A 15 nm anatase dominated film was found to possess the highest photocatalytic activity in all film series. Furthermore almost three times better photocatalytic activity was discovered in the doped series compared to undoped films. The doped films also had lower resistivity. The results from X-ray photoemission spectroscopy showed evidence for interstitial nitrogen in the titanium dioxide structure. Besides, there was a minor red shift observable in the thickest samples. In addition the film conductivity was discovered to increase with the feeding pressure of ammonium hydroxide in the oxidant precursor. This may indicate that nitrogen doping has caused the decrease in the resistivity and therefore has an impact as an enhanced photocatalytic activity. The hot probe test showed that all the anatase or anatase dominant films were p-type and all the rutile dominant films were n-type. The best photocatalytic activity was shown by anatase-dominant films containing a small amount of rutile. It may be that p-n-junctions are formed between p-type anatase and n-type rutile which cause carrier separation and slow down the recombination rate. The combination of nitrogen doping and p-n junction formation results in superior photocatalytic performance. - Highlights: Black-Right-Pointing-Pointer We found all N-doped and undoped anatase dominating films p-type. Black-Right-Pointing-Pointer We found all N-doped and undoped rutile dominating films n-type. Black-Right-Pointing-Pointer We propose that p-n junctions are formed in anatase-rutile mixture films. Black-Right-Pointing-Pointer We found that low level N-doping has increased TiO{sub 2} conductivity. Black

  12. High-Mobility Aligned Pentacene Films Grown by Zone-Casting

    DEFF Research Database (Denmark)

    Duffy, Claudia M.; Andreasen, Jens Wenzel; Breiby, Dag W.

    2008-01-01

    We investigate the growth and field-effect transistor performance of aligned pentacene thin films deposited by zone-casting from a solution of unsubstituted pentacene molecules in a chlorinated solvent. Polarized optical microscopy shows that solution processed pentacene films grow as large...... devices depends strongly on the underlying dielectric. Divinylsiloxane-bis-benzocyclobutene (BCB) resin is found to be a suitable gate dielectric allowing reproducible film deposition and high field-effect mobilities up to 0.4−0.7 cm2/(V s) and on/off ratios of 106−107. A small mobility anisotropy...

  13. Properties of CdS thin films grown by CBD as a function of thiourea concentration

    Energy Technology Data Exchange (ETDEWEB)

    Ximello-Quiebras, J.N.; Contreras-Puente, G.; Rueda-Morales, G.; Vigil, O. [Escuela Superior de Fisica y Matematicas-Instituto Politecnico Nacional, Edificio 9, U.P.A.L.M. 07738 DF (Mexico); Santana-Rodriguez, G. [Instituto de Investigaciones en Materiales, UNAM, CP 04510 (Mexico DF); Morales-Acevedo, A. [CINVESTAV-IPN, Depto. Ingenieria Electrica-SEES, Av. IPN 2508,CP 07360 Mexico, DF (Mexico)

    2006-04-14

    This paper reports a study of the growth rate and optical properties of CdS thin films prepared by the chemical bath deposition technique. For the deposition an aqueous solution of cadmium chloride, ammonium chloride, ammonium hydroxide and thiourea were used, the films were deposited on conducting glass (SnO{sub 2}: F). The growth kinetics is relatively fast when the quantity of thiourea is increased in the deposition solution and higher value of band gap is obtained (E{sub g}=2.44eV). The films show good transmittance in the visible region. (author)

  14. Effect of preheating on the film thickness of contemporary composite restorative materials

    Directory of Open Access Journals (Sweden)

    Dimitrios Dionysopoulos

    2014-12-01

    Conclusion: The film thickness of the composites tested is material dependent. The thickness of the preheated conventional composites is significantly lower than those at room temperature. The conventional composites provide film thickness values greater than those of the flowable composites regardless of preheating temperature.

  15. Molecular interactions in gelatin/chitosan composite films.

    Science.gov (United States)

    Qiao, Congde; Ma, Xianguang; Zhang, Jianlong; Yao, Jinshui

    2017-11-15

    Gelatin and chitosan were mixed at different mass ratios in solution forms, and the rheological properties of these film-forming solutions, upon cooling, were studied. The results indicate that the significant interactions between gelatin and chitosan promote the formation of multiple complexes, reflected by an increase in the storage modulus of gelatin solution. Furthermore, these molecular interactions hinder the formation of gelatin networks, consequently decreasing the storage modulus of polymer gels. Both hydrogen bonds and electrostatic interactions are formed between gelatin and chitosan, as evidenced by the shift of the amide-II bands of polymers. X-ray patterns of composite films indicate that the contents of triple helices decrease with increasing chitosan content. Only one glass transition temperature (Tg) was observed in composite films with different composition ratios, and it decreases gradually with an increase in chitosan proportion, indicating that gelatin and chitosan have good miscibility and form a wide range of blends. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Layer-dependent supercapacitance of graphene films grown by chemical vapor deposition on nickel foam

    KAUST Repository

    Chen, Wei

    2013-03-01

    High-quality, large-area graphene films with few layers are synthesized on commercial nickel foams under optimal chemical vapor deposition conditions. The number of graphene layers is adjusted by varying the rate of the cooling process. It is found that the capacitive properties of graphene films are related to the number of graphene layers. Owing to the close attachment of graphene films on the nickel substrate and the low charge-transfer resistance, the specific capacitance of thinner graphene films is almost twice that of the thicker ones and remains stable up to 1000 cycles. These results illustrate the potential for developing high-performance graphene-based electrical energy storage devices. © 2012 Elsevier B.V. All rights reserved.

  17. Thin-Film Solar Cells with InP Absorber Layers Directly Grown on Nonepitaxial Metal Substrates

    KAUST Repository

    Zheng, Maxwell

    2015-08-25

    The design and performance of solar cells based on InP grown by the nonepitaxial thin-film vapor-liquid-solid (TF-VLS) growth technique is investigated. The cell structure consists of a Mo back contact, p-InP absorber layer, n-TiO2 electron selective contact, and indium tin oxide transparent top electrode. An ex situ p-doping process for TF-VLS grown InP is introduced. Properties of the cells such as optoelectronic uniformity and electrical behavior of grain boundaries are examined. The power conversion efficiency of first generation cells reaches 12.1% under simulated 1 sun illumination with open-circuit voltage (VOC) of 692 mV, short-circuit current (JSC) of 26.9 mA cm-2, and fill factor (FF) of 65%. The FF of the cell is limited by the series resistances in the device, including the top contact, which can be mitigated in the future through device optimization. The highest measured VOC under 1 sun is 692 mV, which approaches the optically implied VOC of ≈795 mV extracted from the luminescence yield of p-InP. The design and performance of solar cells based on indium phosphide (InP) grown by the nonepitaxial thin-film vapor-liquid-solid growth technique is investigated. The cell structure consists of a Mo back contact, p-InP absorber layer, n-TiO2 electron selective contact, and an indium tin oxide transparent top electrode. The highest measured open circuit voltage (VOC) under 1 sun is 692 mV, which approaches the optically implied VOC of ≈795 mV extracted from the luminescence yield of p-InP.

  18. Influence of flow rate on different properties of diamond-like nanocomposite thin films grown by PECVD

    Directory of Open Access Journals (Sweden)

    T. S. Santra

    2012-06-01

    Full Text Available Diamond-like nanocomposite (DLN thin films were deposited on pyrex glass substrate using different flow rate of haxamethyldisiloxane (HMDSO based liquid precursor with nitrogen gas as a glow discharged decomposition by plasma enhanced chemical vapor deposition (PECVD technique. The significant influence of different precursor flow rates on refractive index and thickness of the DLN films was measured by using spectroscopic filmatrics and DEKTAK profilometer. Optical transparency of the DLN thin films was analyzed by UV-VIS-NIR spectrometer. FTIR spectroscopy, provides the information about shifted bonds like SiC2, Si-C, Si-O, C-C, Si-H, C-H, N-H, and O-H with different precursor flow rate. We have estimated the hardness of the DLN films from Raman spectroscopy using Gaussian deconvolution method and tried to investigate the correlation between hardness, refractive index and thickness of the films with different precursor flow rates. The composition and surface morphology of the DLN films were investigated by X-ray photo electron spectroscopy (XPS and atomic force microscopy (AFM respectively. We have analyzed the hardness by intensity ratio (ID/IG of D and G peaks and correlates with hardness measurement by nanoindentation test where hardness increases from 27.8 μl/min to 80.6μl/min and then decreases with increase of flow rate from 80.6μl/min to 149.5μl/min. Finally, we correlates different parameters of structural, optical and tribological properties like film-thickness, refractive index, light transmission, hardness, surface roughness, modulus of elasticity, contact angle etc. with different precursor flow rates of DLN films.

  19. Influence of interface reactions on the YBCO films grown by fluorine-free solution route

    DEFF Research Database (Denmark)

    Zhao, Yue; Wu, Wei; Tang, Xiao

    2015-01-01

    Fabrication of full-stacked coated conductors by all-chemical-solution routes exhibit a great potential in view of further reducing the cost and increasing the throughput for industrialization. Growth of YBa2Cu3O7−x (YBCO) superconducting films by fluorine-free metal organic deposition routes (FF...... superconducting performance when using CLO/YSZ as substrate. Further investigation of compatibility of the buffer layer for FF-derived YBCO films is needed....

  20. Fabrication and characterization of borocarbide thin films grown by in-situ process

    CERN Document Server

    Arisawa, S; Togano, K

    1999-01-01

    We have reported on the fabrication of thin films of YNi sub 2 B sub 2 C for the first time. The process, however, requires the post-annealing at 1050 .deg. C. It is preferable to avoid such a high temperature for practical device applications and we are aiming at establishing an in-situ process at lower temperatures. To obtain films with higher T sub c , it is very important to know the relationship between what we choose as substrates and what we get on them. Three kinds of substrates, polished MgO, unpolished MgO, and polished SrTiO sub 3 were adopted. As for former 2 kinds of substates, superconductive films were successfully fabricated with the T sub c of approx 11K. Further, we discuss the fabrication of thin films of YPd sub 2 B sub 2 C on SrTiO sub 3 substrate. We tried to synthesize the films of the Pd system by RF sputtering technique as well. So far, it is uncertain whether or not the 1221 phase exists in the films. However, the slight reduction of the resistance was observed at 23 K, which is almo...

  1. Preparation, Structural and Dielectric Properties of Solution Grown Polyvinyl Alcohol(PVA) Film

    Science.gov (United States)

    Nangia, Rakhi; Shukla, Neeraj K.; Sharma, Ambika

    2017-08-01

    Flexible dielectrics with high permittivity have been investigated extensively due to their applications in electronic industry. In this work, structural and electrical characteristics of polymer based film have been analysed. Poly vinyl alcohol (PVA) film was prepared by solution casting method. X-ray diffraction (XRD) characterization technique is used to investigate the structural properties. The semi-crystalline nature has been determined by the analysis of the obtained XRD pattern. Electrical properties of the synthesized film have been analysed from the C-V and I-V curves obtained at various frequencies and temperatures. Low conductivity values confirm the insulating behaviour of the film. However, it is found that conductivity increases with temperature. Also, the dielectric permittivity is found to be higher at lower frequencies and higher temperatures, that proves PVA to be an excellent dielectric material which can be used in interface electronics. Dielectric behaviour of the film has been explained based on dipole orientations to slow and fast varying electric field. However further engineering can be done to modulate the structural, electrical properties of the film.

  2. In situ RHEED analysis of epitaxial Gd{sub 2}O{sub 3} thin films grown on Si (001)

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, W.F. [China University of Petroleum, State Key Laboratory of Heavy Oil Processing, Beijing (China); China University of Petroleum, Laboratory of Optic Sensing and Detecting Technology, Beijing (China); Chinese Academy of Sciences, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Beijing (China); Ni, H. [China University of Petroleum, Laboratory of Optic Sensing and Detecting Technology, Beijing (China); Lu, H.B. [Chinese Academy of Sciences, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Beijing (China)

    2013-02-15

    Epitaxial Gd{sub 2}O{sub 3} thin films were successfully grown on Si (001) substrates using a two-step approach by laser molecular-beam epitaxy. At the first step, a {proportional_to}0.8 nm thin layer was deposited at the temperature of 200 {sup circle} C as the buffer layer. Then the substrate temperature was increased to 650 {sup circle} C and in situ annealing for 5 min, and a second Gd{sub 2}O{sub 3} layer with a desired thickness was deposited. The whole growth process is monitored by in situ reflection high-energy electron diffraction (RHEED). In situ RHEED analysis of the growing film has revealed that the first Gd{sub 2}O{sub 3} layer deposition and in situ annealing are the critical processes for the epitaxial growth of Gd{sub 2}O{sub 3} film. The Gd{sub 2}O{sub 3} film has a monoclinic phase characterized by X-ray diffraction. The high-resolution transmission electron microscopy image showed all the Gd{sub 2}O{sub 3} layers have a little bending because of the stress. In addition, a 5-6 nm amorphous interfacial layer between the Gd{sub 2}O{sub 3} film and Si substrate is due to the in situ high temperature annealing for a long time. The successful Gd{sub 2}O{sub 3}/Si epitaxial growth predicted a possibility to develop the new functional microelectronics devices. (orig.)

  3. Ag films grown by remote plasma enhanced atomic layer deposition on different substrates

    Energy Technology Data Exchange (ETDEWEB)

    Amusan, Akinwumi A., E-mail: akinwumi.amusan@ovgu.de; Kalkofen, Bodo; Burte, Edmund P. [Institute of Micro and Sensor Systems, Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg (Germany); Gargouri, Hassan; Wandel, Klaus; Pinnow, Cay [SENTECH Instruments GmbH, Schwarzschildstraße 2, 12489 Berlin (Germany); Lisker, Marco [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany)

    2016-01-15

    Silver (Ag) layers were deposited by remote plasma enhanced atomic layer deposition (PALD) using Ag(fod)(PEt{sub 3}) (fod = 2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) as precursor and hydrogen plasma on silicon substrate covered with thin films of SiO{sub 2}, TiN, Ti/TiN, Co, Ni, and W at different deposition temperatures from 70  to 200 °C. The deposited silver films were analyzed by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) with energy dispersive x-ray spectroscopy, four point probe measurement, ellipsometric measurement, x-ray fluorescence (XRF), and x-ray diffraction (XRD). XPS revealed pure Ag with carbon and oxygen contamination close to the detection limit after 30 s argon sputtering for depositions made at 120 and 200 °C substrate temperatures. However, an oxygen contamination was detected in the Ag film deposited at 70 °C after 12 s argon sputtering. A resistivity of 5.7 × 10{sup −6} Ω cm was obtained for approximately 97 nm Ag film on SiO{sub 2}/Si substrate. The thickness was determined from the SEM cross section on the SiO{sub 2}/Si substrate and also compared with XRF measurements. Polycrystalline cubic Ag reflections were identified from XRD for PALD Ag films deposited at 120 and 200 °C. Compared to W surface, where poor adhesion of the films was found, Co, Ni, TiN, Ti/TiN and SiO{sub 2} surfaces had better adhesion for silver films as revealed by SEM, TEM, and AFM images.

  4. Characteristics of LaB{sub 6} thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Craciun, Valentin; Socol, Gabriel; Craciun, Doina, E-mail: doina.craciun@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, Magurele 077125 (Romania); Cristea, Daniel [Materials Science Department, Transilvania University of Brasov, Brasov 500036 (Romania); Lambers, Eric [Major Analytical Instrumentation Center (MAIC), University of Florida, Gainesville, Florida 32611 (United States); Trusca, Roxana [Faculty of Applied Chemistry and Material Science, Department of Science and Engineering of Oxide Materials and Nanomaterials, University Politehnica of Bucharest, Bucharest 011061, 060042 (Romania); Fairchild, Steven [Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, Ohio 45433-7707 (United States); Back, Tyson; Gruen, Greggory [Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, Ohio 45433-7707 and Energy and Environmental Engineering Division, University of Dayton Research Institute, Dayton, Ohio 45469-0170 (United States)

    2016-09-15

    LaB{sub 6} thin films were deposited at a temperature of 500 °C under vacuum or Ar atmosphere by the pulsed laser deposition technique on (100) Si substrates using a KrF laser. Grazing incidence x-ray diffraction investigations found that films were nanocrystalline, with grain size dimensions from 86 to 102 nm and exhibited microstrain values around 1.1%. Simulations of the x-ray reflectivity curves acquired from the deposited films showed that films had a density around 4.55 g/cm{sup 3}, and were very smooth, with a surface roughness root-mean-square of 1.5 nm, which was also confirmed by scanning electron and atomic force microscopy measurements. All films were covered by a ∼2 nm thick contamination layer that formed when samples were exposed to the ambient. Auger electron spectroscopy investigations found very low oxygen impurity levels below 1.5 at. % once the contamination surface layer was removed by Ar ion sputtering. Four point probe measurements showed that films were conductive, with a resistivity value around 200 μΩ cm for those deposited under Ar atmosphere and slightly higher for those deposited under vacuum. Nanoindentation and scratch investigations showed that films were rather hard, H ∼ 16 GPa, E ∼ 165 GPa, and adherent to the substrate. Thermionic emission measurements indicated a work function value of 2.66 eV, very similar to other reported values for LaB{sub 6}.

  5. Ferroelectric properties of lightly doped La:HfO2 thin films grown by plasma-assisted atomic layer deposition

    Science.gov (United States)

    Kozodaev, M. G.; Chernikova, A. G.; Korostylev, E. V.; Park, M. H.; Schroeder, U.; Hwang, C. S.; Markeev, A. M.

    2017-09-01

    The structural and ferroelectric properties of lightly La-doped (1 mol. %) HfO2 thin films grown by plasma-assisted atomic layer deposition were examined. An annealing temperature as low as 400 °C crystallized the film into the desired orthorhombic phase, which resulted in it displaying promising ferroelectric performance. The remanent polarization (Pr) increased with annealing temperature, but the performance enhancement seemed to saturate at 500 °C. A slight decrease in the dielectric constant, which was associated with the preferential formation of a polar orthorhombic phase at higher temperatures, was also observed. The long-term wake-up effect, i.e., a marked rise in the 2Pr value during field cycling, was demonstrated for films processed at all annealing temperatures. The presence of domain groups with opposite internal electric biases was found in the pristine state, while the internal bias distribution became more uniform during wake-up. The endurance of up to 4 × 108 switching cycles without marked fatigue using bipolar pulses with a duration of 600 ns, and an amplitude of ±3 MV/cm was demonstrated.

  6. Effect of substrates and thickness on optical properties in atomic layer deposition grown ZnO thin films

    Science.gov (United States)

    Pal, Dipayan; Singhal, Jaya; Mathur, Aakash; Singh, Ajaib; Dutta, Surjendu; Zollner, Stefan; Chattopadhyay, Sudeshna

    2017-11-01

    Atomic Layer Deposition technique was used to grow high quality, very low roughness, crystalline, Zinc Oxide (ZnO) thin films on silicon (Si) and fused quartz (SiO2) substrates to study the optical properties. Spectroscopic ellipsometry results of ZnO/Si system, staggered type-II quantum well, demonstrate that there is a significant drop in the magnitudes of both the real and imaginary parts of complex dielectric constants and in near-band gap absorption along with a blue shift of the absorption edge with decreasing film thickness at and below ∼20 nm. Conversely, UV-vis absorption spectroscopy of ZnO/SiO2, thin type-I quantum well, consisting of a narrower-band gap semiconductor grown on a wider-band gap (insulator) substrate, shows the similar thickness dependent blue-shift of the absorption edge but with an increase in the magnitude of near-band gap absorption with decreasing film thickness. Thickness dependent blue shift, energy vs. 1/d2, in two different systems, ZnO/Si and ZnO/SiO2, show a difference in their slopes. The observed phenomena can be consistently explained by the corresponding exciton (or carrier/s) deconfinement and confinement effects at the ZnO/Si and ZnO/SiO2 interface respectively, where Tanguy-Elliott amplitude pre-factor plays the key role through the electron-hole overlap factor at the interface.

  7. Aluminum diffusion in ZnTe films grown on GaSb substrates for n-type doping

    Energy Technology Data Exchange (ETDEWEB)

    DiNezza, Michael J.; Zhang, Qiang; Ding, Ding; Zhang, Yong-Hang [Center for Photonics Innovation, Arizona State University, Tempe, AZ (United States); School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ (United States); Fan, Jin [Center for Photonics Innovation, Arizona State University, Tempe, AZ (United States); Department of Physics, Arizona State University, Tempe, AZ (United States); Liu, Xinyu; Furdyna, Jacek K. [Department of Physics, University of Notre Dame, Notre Dame, IN (United States)

    2012-08-15

    ZnTe PN homojunctions are fabricated using thermal diffusion of Al into a ZnTe film grown on lattice-matched GaSb substrates by molecular beam epitaxy. Rectifying J-V characteristics and the photovoltaic effect are observed which suggests that n-type ZnTe has been successfully achieved. The reverse bias breakdown voltage is found to be dependent on annealing condition and acceptor concentration, and the trend agrees with PN junction theory. Secondary ion mass spectrometer depth profiles of the Al film show that Zn and Te out-diffuse into the Al film during annealing. This out-diffusion is undesirable because it may result in Zn vacancies which compensate Al donor atoms. Photoluminescence measurements of annealed ZnTe samples without the Al diffusion layer show strong band-edge luminescence at room temperature. Midgap luminescence also appears for annealed samples but the intensity is lower than the band-edge peak. This technique may lead to a better understanding of the n-type doping problem for ZnTe, and could lead to in-situdoping techniques and treatments. Successful n-type doping of ZnTe with low resistivity will enable high-efficiency optoelectronic devices operating at pure-green wavelengths (550 nm) (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Structural ordering, morphology and optical properties of amorphous Al{sub x}In{sub 1−x}N thin films grown by plasma-assisted dual source reactive evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, M., E-mail: alizadeh_kozerash@yahoo.com [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ganesh, V. [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Mehdipour, H. [Plasma Nanoscience @ Complex Systems, The University of Sydney, New South Wales 2006 (Australia); Department of Physics, Sharif University of Technology, Tehran 11155-9161 (Iran, Islamic Republic of); Nazarudin, N.F.F.; Goh, B.T.; Shuhaimi, A. [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Rahman, S.A., E-mail: saadah@um.edu.my [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-05-25

    Highlights: • In-rich and Al-rich Al{sub x}In{sub 1−x}N films were grown by plasma-aided reactive evaporation. • The A{sub 1}(LO) phonon mode of the Al-rich films exhibits two-mode behavior. • The band gap of the films was tuned from 1.08 to 2.50 eV. • A bowing parameter of 4.3 eV was calculated for the grown Al{sub x}In{sub 1−x}N films. • The morphology was changed from clusters to uniformly shaped grains by decreasing x. - Abstract: Amorphous aluminum indium nitride (Al{sub x}In{sub 1−x}N) thin films were deposited on quartz substrates by plasma-assisted dual source reactive evaporation system. In-rich (x = 0.10 and 0.18) and Al-rich (x = 0.60 and 0.64) films were prepared by simply varying an AC voltage applied to indium wire. The X-ray-diffraction patterns revealed a small broad peak assigned to Al{sub 0.10}In{sub 0.90}N (0 0 2) plane, but no perceivable peaks assigned to crystalline Al{sub x}In{sub 1−x}N were observed for the films with x = 0.18, 0.60 and 0.64. The morphology of the film was changed from clusters of small grains to uniformly shaped particles with decrease of x. The band gap energy of the films increased from 1.08 eV to 2.50 eV as the Al composition varied from 0.1 to 0.64. Also, Raman results indicated that E{sub 2}(high) and A{sub 1}(LO) peaks of the Al{sub x}In{sub 1−x}N films are remarkably blue-shifted by increasing x and the A{sub 1}(LO) phonon mode of the Al-rich films exhibits two-mode behavior. A bowing parameter of 4.3 eV was obtained for AlInN films. The extrapolated value from bowing equation was 0.85 eV for band gap energy of InN.

  9. Influence of composite processing on the properties of CNT grown on carbon surfaces

    Science.gov (United States)

    Guignier, Claire; Bueno, Marie-Ange; Camillieri, Brigitte; Durand, Bernard

    2018-01-01

    Carbon nanotubes (CNT) grafted on carbon fibres (CF) are the subject of more and more studies on the reinforcement of composite materials thanks to the CNT' mechanical properties. This study concerns the growth of CNT directly on CF by the flame method, which is an assembly-line process. However the industrial-scale use of this method and of the composite processing leads to stresses on the CNT-grafted fabrics, such as friction and pulling-out. The aim of this study is to determine the behaviour of the CNT under these kinds of stresses and to study theirs consequences in composite processing. For this purpose, adhesion tests and friction tests were performed as well as analysis of the surface by Scanning Electron Microscopy (SEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). In friction tests, CNT formed a transfer film, and its effect on the wettability of the fabric with epoxy resin is determined. Finally, the wear of the CNT does not influence the wettability of the fabric. Furthermore, it is proven that the nature of the catalyst needed to grow the CNT modifies the behaviour of the surface.

  10. Investigation of mechanical properties of CVD grown titanium silicon nitride thin films under reduced atmosphere

    Science.gov (United States)

    Guha, Spandan; Das, Soham; Bandyopadhyay, Asish; Das, Santanu; Swain, Bibhu P.

    2018-01-01

    Titanium silicon nitride (TiSiN) thin films were deposited by thermal chemical vapour deposition using TiO2 + Si3N4 powder with different H2 flow rates. Morphological, structural, and mechanical properties of deposited TiSiN films were characterized using different techniques by SEM, XRD, Raman, and nano-indentation. SEM images reveal that surface roughness of TiSiN thin films decreased with increasing of H2 flow rate. The Raman spectroscopy indicated that the intensity of acoustic phonon mode decreases, whereas intensity of optical phonon mode increases with increasing of H2 flow rate. The maximum hardness, Young's modulus, and yield strength of the TiSiN films are 18.23, 185.26, and 83.2 GPa, respectively. The crystallite size and lattice strain of TiSiN thin films vary 2.08-4.43 nm and 0.02-0.055, respectively, for different H2 flow rates. The quantitative and qualitative analyses of TiSiN thin were carried out using the Origin 9.0 software.

  11. Single orientation graphene synthesized on iridium thin films grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Dangwal Pandey, A., E-mail: arti.pandey@desy.de; Grånäs, E.; Shayduk, R.; Noei, H.; Vonk, V. [Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg (Germany); Krausert, K.; Franz, D.; Müller, P.; Keller, T. F.; Stierle, A., E-mail: andreas.stierle@desy.de [Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg (Germany); Fachbereich Physik, Universität Hamburg, D-22607 Hamburg (Germany)

    2016-08-21

    Heteroepitaxial iridium thin films were deposited on (0001) sapphire substrates by means of molecular beam epitaxy, and subsequently, one monolayer of graphene was synthesized by chemical vapor deposition. The influence of the growth parameters on the quality of the Ir films, as well as of graphene, was investigated systematically by means of low energy electron diffraction, x-ray reflectivity, x-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Our study reveals (111) oriented iridium films with high crystalline quality and extremely low surface roughness, on which the formation of large-area epitaxial graphene is achieved. The presence of defects, like dislocations, twins, and 30° rotated domains in the iridium films is also discussed. The coverage of graphene was found to be influenced by the presence of 30° rotated domains in the Ir films. Low iridium deposition rates suppress these rotated domains and an almost complete coverage of graphene was obtained. This synthesis route yields inexpensive, air-stable, and large-area graphene with a well-defined orientation, making it accessible to a wider community of researchers for numerous experiments or applications, including those which use destructive analysis techniques or irreversible processes. Moreover, this approach can be used to tune the structural quality of graphene, allowing a systematic study of the influence of defects in various processes like intercalation below graphene.

  12. Magnetic coupling mechanisms in particle/thin film composite systems

    Directory of Open Access Journals (Sweden)

    Giovanni A. Badini Confalonieri

    2010-12-01

    Full Text Available Magnetic γ-Fe2O3 nanoparticles with a mean diameter of 20 nm and size distribution of 7% were chemically synthesized and spin-coated on top of a Si-substrate. As a result, the particles self-assembled into a monolayer with hexagonal close-packed order. Subsequently, the nanoparticle array was coated with a Co layer of 20 nm thickness. The magnetic properties of this composite nanoparticle/thin film system were investigated by magnetometry and related to high-resolution transmission electron microscopy studies. Herein three systems were compared: i.e. a reference sample with only the particle monolayer, a composite system where the particle array was ion-milled prior to the deposition of a thin Co film on top, and a similar composite system but without ion-milling. The nanoparticle array showed a collective super-spin behavior due to dipolar interparticle coupling. In the composite system, we observed a decoupling into two nanoparticle subsystems. In the ion-milled system, the nanoparticle layer served as a magnetic flux guide as observed by magnetic force microscopy. Moreover, an exchange bias effect was found, which is likely to be due to oxygen exchange between the iron oxide and the Co layer, and thus forming of an antiferromagnetic CoO layer at the γ-Fe2O3/Co interface.

  13. Room-Temperature Plastic Deformation of Strontium Titanate Crystals Grown from Different Chemical Compositions

    Directory of Open Access Journals (Sweden)

    Atsutomo Nakamura

    2017-11-01

    Full Text Available Oxide materials have the potential to exhibit superior mechanical properties in terms of high yield point, high melting point, and high chemical stability. Despite this, they are not widely used as a structural material due to their brittle nature. However, this study shows enhanced room-temperature plasticity of strontium titanate (SrTiO3 crystals through the control of the chemical composition. It is shown that the deformation behavior of SrTiO3 crystals at room temperature depends on the Sr/Ti ratio. It was found that flow stresses in deforming SrTiO3 crystals grown from a powder with the particular ratio of Sr/Ti = 1.04 are almost independent of the strain rate because of the high mobility of dislocations in such crystals. As a result, the SrTiO3 crystals can deform by dislocation slip up to a strain of more than 10%, even at a very high strain rate of 10% per second. It is thus demonstrated that SrTiO3 crystals can exhibit excellent plasticity when chemical composition in the crystal is properly controlled.

  14. Proximate composition, mineral content and antinutritional factors of some capsicum (Capsicum annum varieties grown in Ethiopia

    Directory of Open Access Journals (Sweden)

    Tilahun B.

    2011-12-01

    Full Text Available This study was conducted to generate baseline information on the nutritional composition, mineral content and antinutritional factors of three capsicum varieties (Marako fana, Bako local and Oda haro grown in Ethiopia. In relation to proximate composition, Marako fana, Bako local and Oda haro contained 9.2, 9.0 and 8.8% moisture; 11.9, 8.8 and 9.2% crude protein; 27.3, 26.0 and 28.6% crude fiber and 11.2, 9.5 and 9.2% fat (oleoresin on wet weight basis. They also contained 1.7, 1.6 and 1.8 mg/100 g potassium; 27.2, 38.2 and 54.6 mg/100 g calcium and 7.2, 6.9 and 9.6 mg/100 g iron on wet weight basis. Tannin was found to be 0.142, 0.164 and 0.148 mg/100 g, respectively, while phytate was not detected in any of the samples. Analysis of variance and LSD (least significant difference test revealed that protein and oleoresin of Marako fana were significantly higher (p<0.05 than Bako local and Oda haro. Potassium, calcium and iron contents of Oda haro were significantly higher (p<0.05. Based on these results Marako fana is preferable for large scale production of oleoresin, while Oda haro is nutritionally preferable because it contains high amounts of potassium, calcium and iron.

  15. 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

    2015-11-01

    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.

  16. Effect of nitrogen flow rate on structural, morphological and optical properties of In-rich In{sub x}Al{sub 1−x}N thin films grown by plasma-assisted dual source reactive evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, M., E-mail: alizadeh_kozerash@yahoo.com [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ganesh, V.; Goh, B.T. [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Dee, C.F.; Mohmad, A.R. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, Bangi, Selangor (Malaysia); Rahman, S.A., E-mail: saadah@um.edu.my [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-08-15

    Highlights: • In-rich In{sub x}Al{sub 1−x}N films were grown by Plasma-aided reactive evaporation. • Effect of nitrogen flow rate on the films properties was investigated. • The band gap of the films was varied from 1.17 to 0.90 eV. • By increasing N{sub 2} flow rate the In{sub x}Al{sub 1−x}N films tend to turn into amorphous state. • At higher N{sub 2} flow rate agglomeration of the particles is highly enhanced. - Abstract: In-rich In{sub x}Al{sub 1−x}N thin films were deposited on quartz substrate at various nitrogen flow rates by plasma-assisted dual source reactive evaporation technique. The elemental composition, surface morphology, structural and optical properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Raman spectroscopy, X-ray diffraction (XRD), UV–vis spectrophotometer and photoluminescence (PL) measurements. XPS results revealed that the indium composition (x) of the In{sub x}Al{sub 1−x}N films increases from 0.90 to 0.97 as the nitrogen flow rate is increased from 40 to 100 sccm, respectively. FESEM images of the surface and cross-sectional microstructure of the In{sub x}Al{sub 1−x}N films showed that by increasing the N{sub 2} flow rate, the grown particles are highly agglomerated. Raman and XRD results indicated that by increasing nitrogen flow rate the In-rich In{sub x}Al{sub 1−x}N films tend to turn into amorphous state. It was found that band gap energy of the films are in the range of 0.90–1.17 eV which is desirable for the application of full spectra solar cells.

  17. Modeling the transport properties of epitaxially grown thermoelectric oxide thin films using spectroscopic ellipsometry

    KAUST Repository

    Sarath Kumar, S. R.

    2012-02-01

    The influence of oxygen vacancies on the transport properties of epitaxial thermoelectric (Sr,La)TiO3 thin films is determined using electrical and spectroscopic ellipsometry (SE) measurements. Oxygen vacancy concentration was varied by ex-situ annealing in Ar and Ar/H2. All films exhibited degenerate semiconducting behavior, and electrical conductivity decreased (258–133 S cm−1) with increasing oxygen content. Similar decrease in the Seebeck coefficient is observed and attributed to a decrease in effective mass (7.8–3.2 me ), as determined by SE. Excellent agreement between transport properties deduced from SE and direct electrical measurements suggests that SE is an effective tool for studying oxide thin film thermoelectrics.

  18. Transparent conducting ZnO-CdO mixed oxide thin films grown by the sol-gel method.

    Science.gov (United States)

    Pathak, Trilok K; Rajput, Jeevitesh K; Kumar, Vinod; Purohit, L P; Swart, H C; Kroon, R E

    2017-02-01

    Mixed oxides of zinc and cadmium with different proportions were deposited on ordinary glass substrates using the sol-gel spin coating method under optimized deposition conditions using zinc acetate dihydrate and cadmium acetate dihydrate as precursors. X-ray diffraction patterns confirmed the polycrystalline nature of the films. A combination of cubic CdO and hexagonal wurtzite ZnO phases was observed. The oxidation states of Zn, Cd and O in the deposited films were determined by X-ray photoelectron spectroscopic studies. Surface morphology was studied by scanning electron microscopy and atomic force microscopy. The compositional analysis of the thin films was studied by secondary ion mass spectroscopy. The transmittance of the thin films was measured in the range 300-800nm and the optical bandgap was calculated using Tauc's plot method. The bandgap decreased from 3.15eV to 2.15eV with increasing CdO content. The light emission properties of the ZnO:CdO thin films were studied by photoluminescence spectra recorded at room temperature. The current-voltage characteristics were also assessed and showed ohmic behaviour. The resistance decreased with increasing CdO content. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. p-type conduction in nitrogen-doped SnO{sub 2} films grown by thermal processing of tin nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Pan, S.S.; Wang, S.; Zhang, Y.X.; Luo, Y.Y.; Kong, F.Y.; Xu, S.C.; Xu, J.M.; Li, G.H. [Chinese Academy of Sciences, Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Nanostructures, Institute of Solid State Physics, Hefei (China)

    2012-11-15

    p-type nitrogen-doped SnO{sub 2} (SnO{sub 2}:N) films were grown by thermal processing of amorphous tin nitride films at temperatures between 350 and 500 {sup circle} C in flowing O{sub 2}-Ar gas mixture. From high-resolution X-ray photoelectron spectroscopy (XPS) and X-ray diffraction patterns, it is deduced that the N atoms replace the O atoms in the SnO{sub 2} lattice. The N dopant is more tightly bound in SnO{sub 2}:N at higher thermal oxidation temperatures deduced from the XPS results. The hole concentration obtained at an oxidation temperature of 400 {sup circle} C is 1.87 x 10{sup 19} cm{sup -3}, which is dramatically enhanced compared to previous reports. Our results indicate that the high-temperature thermal oxidation of tin nitride is a facile and effective route to alleviate the self-compensation effect, reduce the content of {gamma}-N{sub 2} double donors, and reinforce the stability of N dopant in the SnO{sub 2}:N films. (orig.)

  20. Leaf chemical composition of twenty-one Populus hybrid clones grown under intensive culture

    Science.gov (United States)

    Richard E. Dickson; Philip R. Larson

    1976-01-01

    Leaf material from 21 nursery-grown Populus hybrid clones was analyzed for three nitrogen fractions (total N, soluble protein, and soluble amino acids) and three carbhydrate fractions (reducing sugars, total soluble sugars, and total nonstructural carbohydrates-TNC). In addition, nursery-grown green ash and silver maple, field-grown bigtooth and trembling aspen, and...

  1. Metastable ultrathin crystal in thermally grown SiO2 film on Si substrate

    Directory of Open Access Journals (Sweden)

    Koji Kimoto

    2012-12-01

    Full Text Available A silicon dioxide film on a silicon substrate is the most essential element in semiconductor devices and various advanced materials. We have elucidated the atomic structure of SiO2 films using low-dose scanning transmission electron microscopy (STEM. We have visualized a metastable crystalline SiO2 layer near a silicon substrate, which was not revealed in previous studies probably due to the vitrification caused by electron irradiation. Our experimental results also suggest a crystallographic nature of various surface oxides.

  2. High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded a-plane sapphire at low temperature

    OpenAIRE

    Jayah, Nurul Azzyaty; Yahaya, Hafizal; Mahmood, Mohamad Rusop; TERASAKO, Tomoaki; YASUI, KANJI; Hashim, Abdul Manaf

    2015-01-01

    Hydrothermal zinc oxide (ZnO) thick films were successfully grown on the chemical vapor deposition (CVD)-grown thick ZnO seed layers on a-plane sapphire substrates using the aqueous solution of zinc nitrate dehydrate (Zn(NO3)2). The use of the CVD ZnO seed layers with the flat surfaces seems to be a key technique for obtaining thick films instead of vertically aligned nanostructures as reported in many literatures. All the hydrothermal ZnO layers showed the large grains with hexagonal end fac...

  3. Structural, electrical, and optical properties of polycrystalline NbO{sub 2} thin films grown on glass substrates by solid phase crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Shoichiro [Kanagawa Academy of Science and Technology (KAST), Kawasaki (Japan); Kamisaka, Hideyuki [Department of Chemistry, The University of Tokyo (Japan); Hirose, Yasushi; Hasegawa, Tetsuya [Kanagawa Academy of Science and Technology (KAST), Kawasaki (Japan); Department of Chemistry, The University of Tokyo (Japan)

    2017-03-15

    We investigated the structural, electrical, and optical properties of polycrystalline NbO{sub 2} thin films on glass substrates. The NbO{sub 2} films were crystallized from amorphous precursor films grown by pulsed laser deposition at various oxygen partial pressures (P{sub O2}). The electrical and optical properties of the precursor films systematically changed with P{sub O2}, demonstrating that the oxygen content of the precursor films can be finely controlled with P{sub O2}. The precursors were crystallized into polycrystalline NbO{sub 2} films by annealing under vacuum at 600 C. The NbO{sub 2} films possessed extremely flat surfaces with branching patterns. Even optimized films showed a low resistivity (ρ) of 2 x 10{sup 2} Ω cm, which is much lower than the bulk value of 1 x 10{sup 4} Ω cm, probably because of the inferior crystallinity of the films compared with that of a bulk NbO{sub 2} crystal. Both oxygen-rich and -poor NbO{sub 2} films showed lower ρ than that of the stoichiometric film. The NbO{sub 2} film with the highest ρ showed an indirect bandgap of 0.7 eV. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Enhancement of Fluorescent Labeling via a Composited Thin Film

    Directory of Open Access Journals (Sweden)

    Taikei Suyama

    2014-01-01

    Full Text Available Fluorescent labeling is the prevailing imaging technique in cell biological research. When statistical investigations on a large number of cells are involved, experimental study is required for both low magnification to get a reliable statistical population and high contrast to achieve accurate diagnosis on the nature of the cells’ perturbation. As microscope objectives of low magnification generally yield low collection efficiency, such studies are limited by the fluorescence signal weakness. To overcome this technological insufficiency, Le Moal et al. proposed a method based on metal-coated substrates that enhanced the fluorescence process and improved collection efficiency in fluorescence microscope observation and that could be directly used with a common microscope setup. In this paper, we use an Ag-Si3N4-Ag multilayer film coated on the substrate and numerically analyse the optical behavior of a fluorophore which was placed above the composited film coated on the substrate. The results shows that by using an Ag-Si3N4-Ag composited film the fluorescence imaging can be enhanced remarkably.

  5. Leaf microbiota in an agroecosystem: spatiotemporal variation in bacterial community composition on field-grown lettuce

    Science.gov (United States)

    Rastogi, Gurdeep; Sbodio, Adrian; Tech, Jan J; Suslow, Trevor V; Coaker, Gitta L; Leveau, Johan H J

    2012-01-01

    The presence, size and importance of bacterial communities on plant leaf surfaces are widely appreciated. However, information is scarce regarding their composition and how it changes along geographical and seasonal scales. We collected 106 samples of field-grown Romaine lettuce from commercial production regions in California and Arizona during the 2009–2010 crop cycle. Total bacterial populations averaged between 105 and 106 per gram of tissue, whereas counts of culturable bacteria were on average one (summer season) or two (winter season) orders of magnitude lower. Pyrosequencing of 16S rRNA gene amplicons from 88 samples revealed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the most abundantly represented phyla. At the genus level, Pseudomonas, Bacillus, Massilia, Arthrobacter and Pantoea were the most consistently found across samples, suggesting that they form the bacterial ‘core' phyllosphere microbiota on lettuce. The foliar presence of Xanthomonas campestris pv. vitians, which is the causal agent of bacterial leaf spot of lettuce, correlated positively with the relative representation of bacteria from the genus Alkanindiges, but negatively with Bacillus, Erwinia and Pantoea. Summer samples showed an overrepresentation of Enterobacteriaceae sequences and culturable coliforms compared with winter samples. The distance between fields or the timing of a dust storm, but not Romaine cultivar, explained differences in bacterial community composition between several of the fields sampled. As one of the largest surveys of leaf surface microbiology, this study offers new insights into the extent and underlying causes of variability in bacterial community composition on plant leaves as a function of time, space and environment. PMID:22534606

  6. Tungsten oxide thin films grown by thermal evaporation with high resistance to leaching

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Diogo S. [Universidade Federal de Pelotas (UFPel), RS (Brazil). Centro de Ciencias Quimicas, Farmaceuticas e de Alimentos; Pazinato, Julia C.O.; Freitas, Mauricio A. de; Radtke, Claudio; Garcia, Irene T.S., E-mail: irene@iq.ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Instituto de Quimica; Dorneles, Lucio S. [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Centro de Ciencias Naturais e Exatas

    2014-05-15

    Tungsten oxides show different stoichiometries, crystal lattices and morphologies. These characteristics are important mainly when they are used as photocatalysts. In this work tungsten oxide thin films were obtained by thermal evaporation on (100) silicon substrates covered with gold and heated at 350 and 600 °C, with different deposition times. The stoichiometry of the films, morphology, crystal structure and resistance to leaching were characterized through X-ray photoelectron spectroscopy, micro-Raman spectroscopy, scanning and transmission electron microscopy, X-ray diffractometry, Rutherford backscattering spectrometry and O{sup 16} (α,α')O{sup 16} resonant nuclear reaction. Films obtained at higher temperatures show well-defined spherical nanometric structure; they are composed of WO{sub 3.1} and the presence of hydrated tungsten oxide was also observed. The major crystal structure observed is the hexagonal. Thin films obtained through thermal evaporation present resistance to leaching in aqueous media and excellent performance as photocatalysts, evaluated through the degradation of the methyl orange dye. (author)

  7. Structural transformations in MoO{sub x} thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Lopez, M.A.; Haro-Poniatowski, E. [Departamento de Fisica, Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, 09340, Mexico D. F. (Mexico); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801, Mexico D. F. (Mexico)

    2004-01-01

    In this work, laser-induced crystallization in MoO{sub x} thin films (1.8{<=}x{<=}2.1) is reported. This transformation involves a MoO{sub x} oxidation and subsequently a crystallization process from amorphous MoO{sub 3} to crystalline {alpha}MoO{sub 3}. For comparison purposes crystallization is induced thermally, in an oven, as well. The crystallization kinetics is monitored by Raman spectroscopy; a threshold in the energy density necessary to induce the phase transformation is determined in the case of photo-crystallization. This threshold depends on the type of substrate on which the film is deposited. For the thin films deposited on glass substrates, the structural transformation is from amorphous MoO{sub x} to the thermodynamically stable {alpha}MoO{sub 3} crystalline phase. For the thin films deposited on Si(100) the structural transformation is from amorphous MoO{sub x} to a mixture of {alpha}MoO{sub 3} and the thermodynamically unstable {beta}MoO{sub 3} crystalline phases. The structural transformations are also characterized by scanning electron microscopy and light-transmission experiments. (orig.)

  8. Thermally induced evolution of sol–gel grown WO3 films on ITO/glass substrates

    NARCIS (Netherlands)

    Caruso, T.; Castriota, M.; Policicchio, A.; Fasanella, A.; Santo, M.P. De; Ciuchi, F.; Desiderio, G.; Rosa, S. La; Rudolf, P.; Agostino, R.G.; Cazzanelli, E.

    2014-01-01

    The electronic, morphological and structural properties of WO3 thin films, synthesized via a sol-gel route and deposited on ITO/glass substrates by spin-coating, were analyzed as a function of annealing temperature (100-700 degrees C range) by Scanning Electron Microscopy, Atomic Force Microscopy,

  9. Influence of annealing temperature on ZnO thin films grown by dual ...

    Indian Academy of Sciences (India)

    In electrical characterization as well, when annealing temperature was increased from 400 to 600 °C, room temperature electron mobility enhanced from 6.534 to 13.326 cm2/V s, and then reduced with subsequent increase in temperature. Therefore, 600 °C annealing temperature produced good-quality ZnO film, suitable ...

  10. Structural changes induced spin-reorientation of ultrathin Mn films grown on Ag(001)

    Energy Technology Data Exchange (ETDEWEB)

    Ouarab, N., E-mail: ouarab_nourdine@yahoo.fr [Quantum Physics and Dynamical Systems Laboratory, Ferhat Abbas University of Sétif (Algeria); Semiconductor Technology Research Center for Energetic-(CRTSE), 02, Bd Frantz Fanon Algiers, BP N° 140 (Algeria); Haroun, A. [Quantum Physics and Dynamical Systems Laboratory, Ferhat Abbas University of Sétif (Algeria); Baadji, N. [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland)

    2016-12-01

    The strained body centered tetragonal (bct) Mn ultrathin film from lattice parameter a=2.89 Å to lattice value of 2.73 Å induces anti-ferromagnetic behavior between Mn layers. The magnetic easy axis of Mn film was demonstrated theoretically to switch from the in-plane to out-of-plane by magneto-optical Kerr effect investigation. By including spin–orbit coupling in full potential linearized augmented plane waves and linearized muffin-tin orbitals methods, manganese ultrathin film displays different magnetic behaviors and the spin-reorientation transition is shown to be correlated to these structural changes. The calculated magnetic moment of manganese planes are enhanced and reach a value of ~4.02 μ{sub B}. The polar magneto-optical Kerr effect is calculated for a photon energy range extended to 15 eV. It shows a pronounced peak in visible light. - Highlights: • The applied strain in Mn-bct structure induces anti-ferromagnetic behavior. • The easy magnetization axis is demonstrated to be out-of-plane. • The magnetic moment of Mn-layers are enhanced and reach a value of ~4.02 μ{sub B}. • Kerr spectra show significant polar responses for Mn films in the visible range. • The prominent structures in the Kerr spectra have been identified.

  11. A novel epitaxially grown LSO-based thin-film scintillator for micro-imaging using hard synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Douissard, P.A.; Martin, T.; Chevalier, V.; Rack, A. [European Synchrotron Radiat Facil, F-38043 Grenoble, (France); Cecilia, A.; Baumbach, T.; Rack, A. [Karlsruhe Inst Technol ANKA, D-76021 Karlsruhe, (Germany); Couchaud, M. [CEA LETI, F-38054 Grenoble, (France); Dupre, K. [FEE GmbH, D-55743 Idar Oberstein, (Germany); Kuhbacher, M. [Helmholtz Zentrum Berlin Mat and Energie, D-14109 Berlin, (Germany)

    2010-07-01

    The efficiency of high-resolution pixel detectors for hard X-rays is nowadays one of the major criteria which drives the feasibility of imaging experiments and in general the performance of an experimental station for synchrotron-based microtomography and radiography. Here the luminescent screen used for the indirect detection is focused on in order to increase the detective quantum efficiency a novel scintillator based on doped Lu{sub 2}SiO{sub 5} (LSO), epitaxially grown as thin film via the liquid phase epitaxy technique. It is shown that, by using adapted growth and doping parameters as well as a dedicated substrate, the scintillation behaviour of a LSO-based thin crystal together with the high stopping power of the material allows for high-performance indirect X-ray detection. In detail, the conversion efficiency, the radioluminescence spectra, the optical absorption spectra under UV/visible-light and the afterglow are investigated. A set-up to study the effect of the thin-film scintillator's temperature on its conversion efficiency is described as well it delivers knowledge which is important when working with higher photon flux densities and the corresponding high heat load on the material. Additionally, X-ray imaging systems based on different diffraction-limited visible-light optics and CCD cameras using among others LSO-based thin film are compared. Finally, the performance of the LSO thin film is illustrated by imaging a honey bee leg, demonstrating the value of efficient high-resolution computed tomography for life sciences. (authors)

  12. Interface study between nanostructured tantalum nitride films and carbon nanotubes grown by chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bouchet-Fabre, B., E-mail: brigitte.bouchet-fabre@cea.fr [Nanosciences and Innovation, CEA/IRAMIS/NIMBE, CEA-Saclay, 91191 Gif sur Yvette Cedex (France); Pinault, M.; Foy, E. [Nanosciences and Innovation, CEA/IRAMIS/NIMBE, CEA-Saclay, 91191 Gif sur Yvette Cedex (France); Hugon, M.C.; Minéa, T. [Laboratoire de Physique des Gaz et des Plasmas (UMR 8578), Université Paris-Sud, Bat. 210, 91405 Orsay cedex (France); Mayne-L’Hermite, M. [Nanosciences and Innovation, CEA/IRAMIS/NIMBE, CEA-Saclay, 91191 Gif sur Yvette Cedex (France)

    2014-10-01

    Highlights: • Our paper deals with the understanding of the carbon nanotubes growth parameters following the use of specific thin nitride buffer films. • For a large choice of buffer, we use ultra thin films elaborated by the very new method: high power pulsed magnetron sputtering; it allows a larger nitrogen incorporation in the films and lead to out of equilibrium phase formation. • Then by a multiscale investigation, developing a structural, a chemical and a morphology approach, we lead to some conclusion on the correlation between the phase transition for the buffer and morphology transition for the CNTs. • That is a new and deep approach. - Abstract: We present the role of nitrogen content in tantalum nitride ultra-thin buffers, on the carbon nanotubes (CNTs) growth by chemical vapour deposition at 850 °C, assisted by ferrocene as catalyst source. Tantalum nitride (TaN{sub x}) films with a very large range of concentration x = [0, 1.8] and various nanostructures, from amorphous Ta(N) to Ta{sub 3}N{sub 5}, were deposited by Highly Pulsed Plasma Magnetron Sputtering. The buffer films are characterized after heat treatment at 850 °C, and after the CNT growth, by wide angle X-ray scattering in grazing incidence and scanning electron microscopy. The CNT diameter explored by transition electron microscopy shows an all-out value for under stoichiometric thin films (Ta{sub 1}-N{sub 1−δ}, Ta{sub 3}-N{sub 5−δ}) and a minimum value just above the stoichiometric phases (Ta{sub 1}-N{sub 1+δ}, Ta{sub 3}-N{sub 5+δ}). Firstly one shows that the buffer films under the heat treatment present surface modification highly dependent on their initial state, which influences the catalyst particles diffusion. Secondly at the stoichiometric TaN phase we show that a specific ternary phase FeTa{sub 2}O{sub 6} is formed at the interface CNT/buffer, not present in the other cases, leading to a special CNT growth condition.

  13. The effects of thermal annealing on the structure and the electrical transport properties of ultrathin gadolinia-doped ceria films grown by pulsed laser deposition

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Heiroth, S.; Pryds, Nini

    2011-01-01

    Ultrathin crystalline films of 10 mol% gadolinia-doped ceria (CGO10) are grown on MgO (100) substrates by pulsed laser deposition at a moderate temperature of 400°C. As-deposited CGO10 layers of approximately 4 nm, 14 nm, and 22 nm thickness consist of fine grains with dimensions ≤∼11 nm. The fil...... templates for the moderate temperature growth of thick solid electrolyte films with improved oxygen transport properties....

  14. Nonlinear Analysis of Actuation Performance of Shape Memory Alloy Composite Film Based on Silicon Substrate

    Directory of Open Access Journals (Sweden)

    Shuangshuang Sun

    2014-01-01

    Full Text Available The mechanical model of the shape memory alloy (SMA composite film with silicon (Si substrate was established by the method of mechanics of composite materials. The coupled action between the SMA film and Si substrate under thermal loads was analyzed by combining static equilibrium equations, geometric equations, and physical equations. The material nonlinearity of SMA and the geometric nonlinearity of bending deformation were both considered. By simulating and analyzing the actuation performance of the SMA composite film during one cooling-heating thermal cycle, it is found that the final cooling temperature, boundary condition, and the thickness of SMA film have significant effects on the actuation performance of the SMA composite film. Besides, the maximum deflection of the SMA composite film is affected obviously by the geometric nonlinearity of bending deformation when the thickness of SMA film is very large.

  15. Synthesis of nanocrystalline Cu{sub 2}ZnSnS{sub 4} thin films grown by the spray-pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Chandel, Tarun, E-mail: tarunchandel777@yahoo.com; Singh, Joginder; Rajaram, P. [School of Studies in Physics, Jiwaji University, Gwalior (MP), India-474011 (India)

    2015-08-28

    Spray pyrolysis was used to deposit Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films on soda lime glass substrates at 300 °C. Aqueous solutions of copper chloride, zinc chloride, stannous chloride and thiourea were mixed together to form the spray liquid. The sprayed films were annealed under vacuum at 350 °C, 400 °C and 450 °C. Structural and optical characterization was performed on the CZTS films using X-ray diffraction (XRD) and UV-VIS spectrophotometry. XRD results indicate that the films are single phase nanocrystalline CZTS. Optical studies show that the optical gap values are 1.44 eV for the as-grown film and 1.46 eV, 1.48 eV and 1.49 eV for the films annealed at 350 °C, 400 °C and 450 °C, respectively.

  16. Properties of La and Nb-modified PZT thin films grown by radio frequency assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Verardi, P. [CNR-Istituto di Acustica, Via del Fosso del Cavaliere 100, I-00133 Rome (Italy); Craciun, F. [CNR-Istituto dei Sistemi Complessi, Via del Fosso del Cavaliere 100, I-00133 Rome (Italy); Dinescu, M. [NILPRP, Bucharest, PO Box MG-16, RO-76900 (Romania)]. E-mail: dinescum@ifin.nipne.ro; Scarisoreanu, N. [NILPRP, Bucharest, PO Box MG-16, RO-76900 (Romania); Moldovan, A. [NILPRP, Bucharest, PO Box MG-16, RO-76900 (Romania); Purice, A. [NILPRP, Bucharest, PO Box MG-16, RO-76900 (Romania); Galassi, C. [CNR-ISTEC, Via Granarolo 64, I 48018 Faenza (Italy)

    2005-04-25

    Lead zirconate titanate ferroelectric thin films added with La and Nb has been grown by radio frequency assisted pulsed laser deposition on Pt/Si, starting from sintered targets. The dielectric properties were measured in a large frequency range and their dependence on the a.c. driving field amplitude has been investigated. A linear decreasing of the dielectric permittivity with frequency logarithm increasing has been evidenced. The most important factor for the driving field amplitude influence on the dielectric properties is the type of vacancies introduced by La and Nb substitutions, which indicates that the dynamics involved in a.c. field behavior is controlled by interaction mechanisms between ferroelectric domain or nanodomain walls and pinning (vacancies) centers.

  17. VO2 Thermochromic Films on Quartz Glass Substrate Grown by RF-Plasma-Assisted Oxide Molecular Beam Epitaxy

    Directory of Open Access Journals (Sweden)

    Dong Zhang

    2017-03-01

    Full Text Available Vanadium dioxide (VO2 thermochromic thin films with various thicknesses were grown on quartz glass substrates by radio frequency (RF-plasma assisted oxide molecular beam epitaxy (O-MBE. The crystal structure, morphology and chemical stoichiometry were investigated systemically by X-ray diffraction (XRD, atomic force microscopy (AFM, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS analyses. An excellent reversible metal-to-insulator transition (MIT characteristics accompanied by an abrupt change in both electrical resistivity and optical infrared (IR transmittance was observed from the optimized sample. Remarkably, the transition temperature (TMIT deduced from the resistivity-temperature curve was reasonably consistent with that obtained from the temperature-dependent IR transmittance. Based on Raman measurement and XPS analyses, the observations were interpreted in terms of residual stresses and chemical stoichiometry. This achievement will be of great benefit for practical application of VO2-based smart windows.

  18. Cobalt hexacyanoferrate nanoparticles and MoO3 thin films grown on carbon fiber cloth for efficient flexible hybrid supercapacitor

    Science.gov (United States)

    Lu, Ke; Song, Bin; Li, Kang; Zhang, Jintao; Ma, Houyi

    2017-12-01

    For the wearable and flexible applications, solid-state supercapacitors have been attracted significant attention owing to their unique features. Herein, we demonstrated the fabrication of a high-energy solid-state hybrid supercapacitor by using cobalt hexacyanoferrate nanoparticles and molybdenum oxide thin films grown on the flexible carbon fiber cloth. The flexible hybrid supercapacitor using a neutral gel electrolyte can be operated in a stable potential window of 2.0 V and delivers a maximal energy density of 67.8 Wh kg-1 at the power density of 1003 W kg-1, outstanding reliability without capacitance degradation under various twisting rates, and remarkable cycling stability retaining 74% of initial capacitance after 10000 cycles.

  19. Combinatorial thin film composition mapping using three dimensional deposition profiles

    Science.gov (United States)

    Suram, Santosh K.; Zhou, Lan; Becerra-Stasiewicz, Natalie; Kan, Kevin; Jones, Ryan J. R.; Kendrick, Brian M.; Gregoire, John M.

    2015-03-01

    Many next-generation technologies are limited by material performance, leading to increased interest in the discovery of advanced materials using combinatorial synthesis, characterization, and screening. Several combinatorial synthesis techniques, such as solution based methods, advanced manufacturing, and physical vapor deposition, are currently being employed for various applications. In particular, combinatorial magnetron sputtering is a versatile technique that provides synthesis of high-quality thin film composition libraries. Spatially addressing the composition of these thin films generally requires elemental quantification measurements using techniques such as energy-dispersive X-ray spectroscopy or X-ray fluorescence spectroscopy. Since these measurements are performed ex-situ and post-deposition, they are unable to provide real-time design of experiments, a capability that is required for rapid synthesis of a specific composition library. By using three quartz crystal monitors attached to a stage with translational and rotational degrees of freedom, we measure three-dimensional deposition profiles of deposition sources whose tilt with respect to the substrate is robotically controlled. We exhibit the utility of deposition profiles and tilt control to optimize the deposition geometry for specific combinatorial synthesis experiments.

  20. Correlation of growth temperature with stress, defect states and electronic structure in an epitaxial GaN film grown on c-sapphire via plasma MBE.

    Science.gov (United States)

    Krishna, Shibin; Aggarwal, Neha; Mishra, Monu; Maurya, K K; Singh, Sandeep; Dilawar, Nita; Nagarajan, Subramaniyam; Gupta, Govind

    2016-03-21

    The relationship of the growth temperature with stress, defect states, and electronic structure of molecular beam epitaxy grown GaN films on c-plane (0001) sapphire substrates is demonstrated. A minimum compressively stressed GaN film is grown by tuning the growth temperature. The correlation of dislocations/defects with the stress relaxation is scrutinized by high-resolution X-ray diffraction and photoluminescence measurements which show a high crystalline quality with significant reduction in the threading dislocation density and defect related bands. A substantial reduction in yellow band related defect states is correlated with the stress relaxation in the grown film. Temperature dependent Raman analysis shows the thermal stability of the stress relaxed GaN film which further reveals a downshift in the E2 (high) phonon frequency owing to the thermal expansion of the lattice at elevated temperatures. Electronic structure analysis reveals that the Fermi level of the films is pinned at the respective defect states; however, for the stress relaxed film it is located at the charge neutrality level possessing the lowest electron affinity. The analysis demonstrates that the generated stress not only affects the defect states, but also the crystal quality, surface morphology and electronic structure/properties.

  1. Scintillating screens based on the LPE grown Tb3Al5O12:Ce single crystalline films

    Science.gov (United States)

    Zorenko, Yuriy; Douissard, Paul-Antoine; Martin, Thierry; Riva, Federica; Gorbenko, Vitaliy; Zorenko, Tetiana; Paprocki, Kazimierz; Iskalieva, Aizhan; Witkiewicz, Sandra; Fedorov, Alexander; Bilski, Paweł; Twardak, Anna

    2017-03-01

    We report in this work the creation of new heavy and efficient Tb3Al5O12:Ce (TbAG:Ce) single crystalline film (SCF) scintillators, grown by LPE method from PbO-B2O3 based flux onto Y3Al5O12 (YAG) and Gd3Ga2.5Al2.5O12 (GAGG) substrates, for different optoelectronic applications. The luminescent and scintillation properties of the TbAG:Ce SCF screens, grown onto different types of substrates, are studied and compared with the properties of the Lu3Al5O12:Ce (LuAG:Ce) and YAG:Ce SCF counterparts. TbAG:Ce SCFs show very high scintillation light yield (LY) under α-particles excitation, which overcomes by 30% the LY of high-quality LuAG:Ce SCF samples. In comparison with YAG:Ce and LuAG:Ce SCFs, TbAG:Ce SCF screens show also significantly lower afterglow (up to 10-4 level at X-ray burst duration of 0.1 s), which is comparable with the afterglow level of the best samples of LSO:Ce, Tb SCFs typically being used now for microimaging. Together with a high light output of X-ray excited luminescence, such extremely low afterglow of TbAG:Ce SCF is a very good reason for future development of scintillating screens based on the mentioned garnet. We also introduce the possibility to create new types of ;film-substrate; hybrid scintillators using the LPE method for simultaneous registration of different components of ionizing radiation and microimaging based on the TbAG:Ce SCF and GAGG:Ce substrates.

  2. Inorganic-organic composite nanoengineered films using self-assembled monolayers for directed zeolite film growth

    Energy Technology Data Exchange (ETDEWEB)

    Dye, R.C.; Hermes, R.E.; Martinez, M.G.; Peachey, N.M.

    1997-10-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Zeolites, or molecular sieves, are aluminosilicate cage structures that are typically grown from a heterogeneous mixture of organic template molecules, inorganic salts of alumina and silica, and water. These zeolites are used in industry for catalytic cracking of hydrocarbons (gasoline manufacture from oil), and contaminant removal from chemical production processes. Within one year, we developed a viable method for the deposition of a quaternary ammonium salt amphiphile onto silicon wafer substrates. Using a biomimetic growth process, we were also able to demonstrate the first thin-film formation of a zeolite structure from such an organic template. Additionally, we synthesized the precursor to another amphiphile which was to be for further studies.

  3. Sulfurization effect on optical properties of Cu2SNS3 thin films grown by two-stage process

    Science.gov (United States)

    Reddy, G. Phaneendra; Reddy, K. T. Ramakrishna

    2017-05-01

    A good phase controlled and impurity free two stage process was used to prepare Cu2SnS3 layers on glass substrates. The layers were prepared by sulfurization of sputtered Cu-Sn metallic precursors by varying the sulfurization temperature (Ts) in the range, 150-450°C, keeping the other deposition parameters constant. A complete investigation of the optical properties of the layers with sulfurization temperature was made by using the optical transmittance and reflectance measurements versus wavelength. The absorption coefficient α, was evaluated using the optical data that showed a α > 104 cm-1 for all the as-grown films. The optical bandgap of the as grown layers was determined from the second derivative diffused reflectance spectra that varied from 1.96 eV to 0.99 eV. Consequently, refractive index and extinction coefficient were calculated from Pankov's relations. In addition, the other optical parameters such as the dielectric constants, dissipation factor and also optical conductivity calculated. A detailed analysis of the dependence of all the above parameters on Ts is reported and discussed.

  4. Measuring the dielectric and optical response of millimeter-scale amorphous and hexagonal boron nitride films grown on epitaxial graphene

    Science.gov (United States)

    Rigosi, Albert F.; Hill, Heather M.; Glavin, Nicholas R.; Pookpanratana, Sujitra J.; Yang, Yanfei; Boosalis, Alexander G.; Hu, Jiuning; Rice, Anthony; Allerman, Andrew A.; Nguyen, Nhan V.; Hacker, Christina A.; Elmquist, Randolph E.; Hight Walker, Angela R.; Newell, David B.

    2018-01-01

    Monolayer epitaxial graphene (EG), grown on the Si face of SiC, is an advantageous material for a variety of electronic and optical applications. EG forms as a single crystal over millimeter-scale areas and consequently, the large scale single crystal can be utilized as a template for growth of other materials. In this work, we present the use of EG as a template to form millimeter-scale amorphous and hexagonal boron nitride (a-BN and h-BN) films. The a-BN is formed with pulsed laser deposition and the h-BN is grown with triethylboron (TEB) and NH3 precursors, making it the first metal organic chemical vapor deposition (MOCVD) process of this growth type performed on epitaxial graphene. A variety of optical and non-optical characterization methods are used to determine the optical absorption and dielectric functions of the EG, a-BN, and h-BN within the energy range of 1 eV–8.5 eV. Furthermore, we report the first ellipsometric observation of high-energy resonant excitons in EG from the 4H polytype of SiC and an analysis on the interactions within the EG and h-BN heterostructure.

  5. Detachment of CVD-grown graphene from single crystalline Ni films by a pure gas phase reaction

    Science.gov (United States)

    Zeller, Patrick; Henß, Ann-Kathrin; Weinl, Michael; Diehl, Leo; Keefer, Daniel; Lippmann, Judith; Schulz, Anne; Kraus, Jürgen; Schreck, Matthias; Wintterlin, Joost

    2016-11-01

    Despite great previous efforts there is still a high need for a simple, clean, and upscalable method for detaching epitaxial graphene from the metal support on which it was grown. We present a method based on a pure gas phase reaction that is free of solvents and polymer supports and avoids mechanical transfer steps. The graphene was grown on 150 nm thick, single crystalline Ni(111) films on Si(111) wafers with YSZ buffer layers. Its quality was monitored by using low energy electron diffraction and scanning tunneling microscopy. The gas phase etching uses a chemical transport reaction, the so-called Mond process, based on the formation of gaseous nickel tetracarbonyl in ~ 1 bar of CO at ~ 75 °C and by adding small amounts of sulfide catalysts. X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy were used to characterize the detached graphene. It was found that the method successfully removes the nickel from underneath the graphene layer, so that the graphene lies on the insulating oxide buffer layer. Small residual particles of nickel sulfide and cracks in the obtained graphene layer were identified. The defect concentrations were comparable to graphene samples obtained by wet chemical etching and by the bubbling transfer.

  6. Atomic probe microscopy of 3C SiC films grown on 6H SiC substrates

    Science.gov (United States)

    Steckl, A. J.; Roth, M. D.; Powell, J. A.; Larkin, D. J.

    1993-01-01

    The surface of 3C SiC films grown on 6H SiC substrates has been studied by atomic probe microscopy in air. Atomic-scale images of the 3C SiC surface have been obtained by STM which confirm the 111 line type orientation of the cubic 3C layer grown on the 0001 plane type surface of the hexagonal 6H substrate. The nearest-neighbor atomic spacing for the 3C layer has been measured to be 3.29 +/- 0.2 A, which is within 7 percent of the bulk value. Shallow terraces in the 3C layer have been observed by STM to separate regions of very smooth growth in the vicinity of the 3C nucleation point from considerably rougher 3C surface regions. These terraces are oriented at right angles to the growth direction. Atomic force microscopy has been used to study etch pits present on the 6H substrate due to high temperature HCl cleaning prior to CVD growth of the 3C layer. The etch pits have hexagonal symmetry and vary in depth from 50 nm to 1 micron.

  7. Transient Photoinduced Absorption in Ultrathin As-grown Nanocrystalline Silicon Films

    Directory of Open Access Journals (Sweden)

    Lioutas Ch

    2007-01-01

    Full Text Available AbstractWe have studied ultrafast carrier dynamics in nanocrystalline silicon films with thickness of a few nanometers where boundary-related states and quantum confinement play an important role. Transient non-degenerated photoinduced absorption measurements have been employed to investigate the effects of grain boundaries and quantum confinement on the relaxation dynamics of photogenerated carriers. An observed long initial rise of the photoinduced absorption for the thicker films agrees well with the existence of boundary-related states acting as fast traps. With decreasing the thickness of material, the relaxation dynamics become faster since the density of boundary-related states increases. Furthermore, probing with longer wavelengths we are able to time-resolve optical paths with faster relaxations. This fact is strongly correlated with probing in different points of the first Brillouin zone of the band structure of these materials.

  8. Structural characteristics of semipolar InN (112l) films grown on yttria stabilized zirconia substrates

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Tomoaki; Ohta, Jitsuo [Institute of Industrial Science (IIS), The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Kobayashi, Atsushi [Department of Applied Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Oshima, Masaharu [Department of Applied Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Core Research for Evolutional Science and Technology of Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0075 (Japan); Fujioka, Hiroshi [Institute of Industrial Science (IIS), The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Core Research for Evolutional Science and Technology of Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0075 (Japan)

    2010-10-15

    We report on the growth of semipolar InN (112 l) films on yttria stabilized zirconia (YSZ) substrates by pulsed laser deposition. We found that the growth orientation can be precisely controlled by utilizing the tendency for the epitaxial relationships of InN [0001] vertical stroke vertical stroke YSZ [111] and InN [11 anti 20] vertical stroke vertical stroke YSZ [11 0] to be maintained. The full-width at half-maximum of the 112 6 X-ray rocking curves for an InN (11 anti 27) film varies from 0.61 to 0.46 depending on the X-ray angle of incidence. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  9. Efficient photovoltaic conversion of graphene-carbon nanotube hybrid films grown from solid precursors

    Science.gov (United States)

    Gan, Xin; Lv, Ruitao; Bai, Junfei; Zhang, Zexia; Wei, Jinquan; Huang, Zheng-Hong; Zhu, Hongwei; Kang, Feiyu; Terrones, Mauricio

    2015-09-01

    Large-area (e.g. centimeter size) graphene sheets are usually synthesized via pyrolysis of gaseous carbon precursors (e.g. methane) on metal substrates like Cu using chemical vapor deposition (CVD), but the presence of grain boundaries and the residual polymers during transfer deteriorates significantly the properties of the CVD graphene. If carbon nanotubes (CNTs) can be covalently bonded to graphene, the hybrid system could possess excellent electrical conductivity, transparency and mechanical strength. In this work, conducting and transparent CNT-graphene hybrid films were synthesized by a facile solid precursor pyrolysis method. Furthermore, the synthesized CNT-graphene hybrid films display enhanced photovoltaic conversion efficiency when compared to devices based on CNT membranes or graphene sheets. Upon chemical doping, the graphene-CNT/Si solar cells reveal power conversion efficiencies up to 8.50%.

  10. S Sensors: Fumarate-Based fcu-MOF Thin Film Grown on a Capacitive Interdigitated Electrode

    KAUST Repository

    Yassine, Omar

    2016-10-31

    Herein we report the fabrication of an advanced sensor for the detection of hydrogen sulfide (H2S) at room temperature, using thin films of rare-earth metal (RE)-based metal-organic framework (MOF) with underlying fcu topology. This unique MOF-based sensor is made via the insitu growth of fumarate-based fcu-MOF (fum-fcu-MOF) thin film on a capacitive interdigitated electrode. The sensor showed a remarkable detection sensitivity for H2S at concentrations down to 100ppb, with the lower detection limit around 5ppb. The fum-fcu-MOF sensor exhibits a highly desirable detection selectivity towards H2S vs. CH4, NO2, H2, and C7H8 as well as an outstanding H2S sensing stability as compared to other reported MOFs. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Mechanical behaviour of composite materials made by resin film infusion

    Directory of Open Access Journals (Sweden)

    Casavola C.

    2010-06-01

    Full Text Available Innovative composite materials are frequently used in designing aerospace, naval and automotive components. In the typical structure of composites, multiple layers are stacked together with a particular sequence in order to give specific mechanical properties. Layers are organized with different angles, different sequences and different technological process to obtain a new and innovative material. From the standpoint of engineering designer it is useful to consider the single layer of composite as macroscopically homogeneous material. However, composites are non homogeneous bodies. Moreover, layers are not often perfectly bonded together and delamination often occurs. Other violations of lamination theory hypotheses, such as plane stress and thin material, are not unusual and in many cases the transverse shear flexibility and the thickness-normal stiffness should be considered. Therefore the real behaviour of composite materials is quite different from the predictions coming from the traditional lamination theory. Due to the increasing structural performance required to innovative composites, the knowledge of the mechanical properties for different loading cases is a fundamental source of concern. Experimental characterization of materials and structures in different environmental conditions is extremely important to understand the mechanical behaviour of these new materials. The purpose of the present work is to characterize a composite material developed for aerospace applications and produced by means of the resin film infusion process (RFI. Different tests have been carried out: tensile, open-hole and filled-hole tensile, compressive, openhole and filled-hole compressive. The experimental campaign has the aim to define mechanical characteristics of this RFI composite material in different conditions: environmental temperature, Hot/Wet and Cold.

  12. Morphology of Copper Tin Sulfide Films Grown by Pulsed Laser Deposition at 248 and 355 nm

    DEFF Research Database (Denmark)

    Ettlinger, Rebecca Bolt; Cazzaniga, Andrea Carlo; Crovetto, Andrea

    Thin films solar cells based on Cu2ZnSnS4 (CZTS) as absorber layer have seen a rapid development leading to a world record of 8.8% [1]. However, other p-type semiconductors with fewer elements and reduced complexity compared to CZTS are also available, such as ternary Cu–Sn–S systems, i.e. Cu2SnS3...

  13. Synthesis and characterization of GaAs thin films grown on ITO substrates

    Science.gov (United States)

    Chamekh, M.; Lajnef, M.; Zerroual, L.; Chtourou, R.

    2010-11-01

    Gallium arsenide (GaAs) thin films have been deposited on ITO-coated glass substrates from acid aqueous solution by electrodeposition technique. The structure and the morphology of the samples were analyzed by X-ray diffraction (XRD) and atomic force microscope (AFM). The optical characteristics were investigated at room temperature using a UV-Vis spectrometer. At lower deposition time, the XRD patterns exhibit a mixture of both cubic and orthorhombic GaAs phases. With further increase of the film thickness, only orthorhombic structure was observed with a preferred (100) orientation. By applying the Debye-Scherrer method, the estimated crystallite size for the (200) orientation ranged from 30 to 50 nm, whereas for the (022) orientation was found to be 13-22 nm. From the AFM measurements, the rms surface roughness ranged between 11.4 and 18.4 nm. The analysis of the optical absorption data of the annealed GaAs film deposited at different times revealed direct band gap energy in the range of 1.60-1.85 eV. The large blueshifts observed in this study can be fully explained by the Burstein-Moss effect.

  14. X-ray reflectivity analysis of titanium dioxide thin films grown by cathodic arc deposition.

    Science.gov (United States)

    Kleiman, A; Lamas, D G; Craievich, A F; Márquez, A

    2014-05-01

    TiO2 thin films deposited by a vacuum arc on a glass substrate were characterized by X-ray reflectivity (XRR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Several thin films with different amounts of deposited TiO2 mass and different deposition and annealing temperatures were studied. A qualitative analysis of the XRD patterns indicated the presence of the anatase and/or rutile crystalline phases in most of the studied samples. From the analysis of the experimental XRR curves--which exhibited a wide angular range of oscillatory behavior--the thickness, mass density and interface roughness were determined. All XRR patterns were well fitted by modeled curves that assume the presence of a single and homogeneous TiO2 layer over which a very thin H2O layer is adsorbed. The thickest H2O adsorption layers were developed in films with the highest anatase content. Our overall results of the XRR analyses are consistent with those derived from the imaging techniques (SEM and AFM).

  15. Superior piezoelectric composite films: taking advantage of carbon nanomaterials.

    Science.gov (United States)

    Saber, Nasser; Araby, Sherif; Meng, Qingshi; Hsu, Hung-Yao; Yan, Cheng; Azari, Sara; Lee, Sang-Heon; Xu, Yanan; Ma, Jun; Yu, Sirong

    2014-01-31

    Piezoelectric composites comprising an active phase of ferroelectric ceramic and a polymer matrix have recently found numerous sensory applications. However, it remains a major challenge to further improve their electromechanical response for advanced applications such as precision control and monitoring systems. We here investigated the incorporation of graphene platelets (GnPs) and multi-walled carbon nanotubes (MWNTs), each with various weight fractions, into PZT (lead zirconate titanate)/epoxy composites to produce three-phase nanocomposites. The nanocomposite films show markedly improved piezoelectric coefficients and electromechanical responses (50%) besides an enhancement of ~200% in stiffness. The carbon nanomaterials strengthened the impact of electric field on the PZT particles by appropriately raising the electrical conductivity of the epoxy. GnPs have been proved to be far more promising in improving the poling behavior and dynamic response than MWNTs. The superior dynamic sensitivity of GnP-reinforced composite may be caused by the GnPs' high load transfer efficiency arising from their two-dimensional geometry and good compatibility with the matrix. The reduced acoustic impedance mismatch resulting from the improved thermal conductance may also contribute to the higher sensitivity of GnP-reinforced composite. This research pointed out the potential of employing GnPs to develop highly sensitive piezoelectric composites for sensing applications.

  16. Optical properties of GaN films grown on SiC/Si

    Energy Technology Data Exchange (ETDEWEB)

    Devrajan, J.; Steckl, A.J. [Cincinnati Univ., OH (United States); Tran, C.A.; Stall, R.A. [EMCORE Corp., Somerset, NJ (United States)

    1998-08-01

    3C SiC grown on Si and on SOI wafers have been used as substrates for GaN growth. The optical properties of GaN/3C SiC are compared to those of GaN grown on the commonly used sapphire substrates and on 6H SiC substrates. Mapping of the PL characteristics over {proportional_to}1 inch substrates indicate a fairly strong edge effect in terms of peak intensity for GaN/3C SiC. Interestingly, the wavelength of the peak intensity was quite uniform over the entire wafer area, with an average value of 365 nm and a standard deviation of {proportional_to}3.3 nm. Mapping of the FWHM of the emission peak exhibited some edge effect, with the lowest values in the center of the wafer. The average PL FWHM was {proportional_to}17 nm, with a standard deviation of {proportional_to}1.4 nm. (orig.) 3 refs.

  17. Effect of sulfurization time on the properties of copper zinc tin sulfide thin films grown by electrochemical deposition

    Science.gov (United States)

    Aldalbahi, Ali; Mkawi, E. M.; Ibrahim, K.; Farrukh, M. A.

    2016-01-01

    We report growth of quaternary Cu2 ZnSnS4 (CZTS) thin films prepared by the electrochemical deposition from salt precursors containing Cu (II), Zn (II) and Sn (IV) metals. The influence of different sulfurization times t (t = 75, 90, 105, and 120 min) on the structural, compositional, morphological, and optical properties, as well as on the electrical properties is studied. The films sulfurized 2 hours showed a prominent kesterite phase with a nearly stoichiometric composition. Samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Raman and UV-VIS-NIR spectrometer at different stages of work. X-ray diffraction and Raman spectroscopy analyses confirmed the formation of phase-pure CZTS films. (FESEM) shows that compact and dense morphology and enhanced photo-sensitivity. STEM - EDS elemental map of CZTS cross-section confirms homogeneous distribution. From optical study, energy gap was enlarged with a changed sulfurization times in the range of 1.37–1.47 eV. PMID:27600023

  18. Effect of sulfurization time on the properties of copper zinc tin sulfide thin films grown by electrochemical deposition.

    Science.gov (United States)

    Aldalbahi, Ali; Mkawi, E M; Ibrahim, K; Farrukh, M A

    2016-09-07

    We report growth of quaternary Cu2 ZnSnS4 (CZTS) thin films prepared by the electrochemical deposition from salt precursors containing Cu (II), Zn (II) and Sn (IV) metals. The influence of different sulfurization times t (t = 75, 90, 105, and 120 min) on the structural, compositional, morphological, and optical properties, as well as on the electrical properties is studied. The films sulfurized 2 hours showed a prominent kesterite phase with a nearly stoichiometric composition. Samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Raman and UV-VIS-NIR spectrometer at different stages of work. X-ray diffraction and Raman spectroscopy analyses confirmed the formation of phase-pure CZTS films. (FESEM) shows that compact and dense morphology and enhanced photo-sensitivity. STEM - EDS elemental map of CZTS cross-section confirms homogeneous distribution. From optical study, energy gap was enlarged with a changed sulfurization times in the range of 1.37-1.47 eV.

  19. Application of nano-TiO2/LDPE composite film on photocatalytic oxidation degradation of dichloromethane.

    Science.gov (United States)

    Suwannahong, Kowit; Liengcharernsit, Winai; Sanongraj, Wipada; Kruenate, Jittiporn

    2012-09-01

    This study focused on the photocatalytic destruction of dichloromethane (DCM) in indoor air using the nano-TiO2/LDPE composite film as an economical photocatalyst. The nano-TiO2 was dispersed in a polyethylene matrix to form composite film. The photocatalytic activity of the nano-TiO2/LDPE composite films was evaluated through the degradation of dichloromethane(DCM) under UV-C irradiance at specific wavelength of 254 nm. The percentage of nano-TiO2 contents varied from 0, 5, and 10% (wt cat./wt LDPE composite film). The results derived from the kinetic model revealed that the photocatalytic rates of 5 and 10 wt.% nano-TiO2/ LDPE composite films follow the first order reaction while the rate of the film without TiO2 followed the zero order reaction. At low concentration of DCM, the rate of photocatalytic degradation of the DCM was slower than that at high DCM concentration. The 10 wt.% of TiO2 content of the nano-TiO2/LDPE composite film yielded the highest degradation efficiency of 78%, followed by the removal efficiency of 55% for the 5 wt.% of TiO2 content of the nano-TiO2/LDPE composite film. In contrast with the composite film containing nano-TiO2, the LDPE film without adding nano-TiO2 expressed the degradation efficiency of 28%.

  20. Structural and magnetic phase transitions in chromium nitride thin films grown by rf nitrogen plasma molecular beam epitaxy

    Science.gov (United States)

    Alam, Khan; Disseler, Steven M.; Ratcliff, William D.; Borchers, Julie A.; Ponce-Pérez, Rodrigo; Cocoletzi, Gregorio H.; Takeuchi, Noboru; Foley, Andrew; Richard, Andrea; Ingram, David C.; Smith, Arthur R.

    2017-09-01

    A magnetostructural phase transition is investigated in single-crystal chromium nitride (CrN) thin films grown by rf plasma molecular beam epitaxy on MgO(001) substrates. While still within the vacuum environment following molecular beam epitaxy growth, in situ low-temperature scanning tunneling microscopy, and in situ variable low-temperature reflection high-energy electron diffraction are applied, revealing an atomically smooth and metallic CrN(001) surface, and an in-plane structural transition from 1 ×1 (primitive CrN unit cell) to √{2 }×√{2 }-R 45∘ with a transition temperature of (278 ±3 ) K, respectively. Ex situ temperature-dependent measurements using neutron diffraction are also performed, looking at the structural peaks and likewise revealing a first-order structural transition along the [111] out-of-plane direction, with transition temperatures of (268 ± 3) K. Turning to the magnetic peaks, neutron diffraction confirms a clear magnetic transition from paramagnetic at room temperature to antiferromagnetic at low temperatures with a sharp, first-order phase transition and a Néel temperature of (270 ±2 ) K or (280 ±2 ) K for two different films. In addition to the experimental measurements of structural and magnetic ordering, we also discuss results from first-principles theoretical calculations which explore various possible magnetostructural models.

  1. Magnetic properties of single-crystal {110} iron films grown on GaAs by molecular beam epitaxy (invited)

    Science.gov (United States)

    Prinz, G. A.; Rado, G. T.; Krebs, J. J.

    1982-03-01

    Single-crystal {110} Fe films, grown for the first time by molecular beam epitaxy on GaAs, have been studied by a variety of techniques in order to determine the dependence of the magnetic properties upon film thickness L and quality, and an overview of these results is presented. The dependence of the ferromagnetic resonance (FMR) field upon its orientation in the (11¯0) plane was measured at 16.4 GHz and shows that the magnetically easy axis is [110] for L<50 Å and [001] for L≳150 Å. A theory of FMR which incorporates magnetocrystalline surface anisotropy is outlined. It successfully interprets the thickness dependence of the FMR data in the ultrathin (L≲50 Å) regime and shows them to be surface dominated. FMR data at 9.2 GHz, which contain both aligned and nonaligned resonance branches, are presented as a function L. In addition, the dependence of the branches on frequency f for 8 GHz

  2. Temperature dependence of gas sensing behaviour of TiO2 doped PANI composite thin films

    Science.gov (United States)

    Srivastava, Subodh; Sharma, S. S.; Sharma, Preetam; Sharma, Vinay; Rajura, Rajveer Singh; Singh, M.; Vijay, Y. K.

    2014-04-01

    In the present work we have reported the effect of temperature on the gas sensing properties of TiO2 doped PANI composite thin film based chemiresistor type gas sensors for hydrogen gas sensing application. PANI and TiO2 doped PANI composite were synthesized by in situ chemical oxidative polymerization of aniline at low temperature. The electrical properties of these composite thin films were characterized by I-V measurements as function of temperature. The I-V measurement revealed that conductivity of composite thin films increased as the temperature increased. The changes in resistance of the composite thin film sensor were utilized for detection of hydrogen gas. It was observed that at room temperature TiO2 doped PANI composite sensor shows higher response value and showed unstable behavior as the temperature increased. The surface morphology of these composite thin films has also been characterized by scanning electron microscopy (SEM) measurement.

  3. Epitaxial ZnO Thin Films on a-Plane Sapphire Substrates Grown by Ultrasonic Spray-Assisted Mist Chemical Vapor Deposition

    Science.gov (United States)

    Nishinaka, Hiroyuki; Kamada, Yudai; Kameyama, Naoki; Fujita, Shizuo

    2009-12-01

    High-quality epitaxial ZnO thin films were grown by an ultrasonic spray-assisted mist chemical vapor deposition (CVD) on a-plane sapphire substrates with ZnO buffer layers. The ZnO thin films were grown with c-axis orientation without notable rotational domains. Surface morphologies and electrical properties were markedly improved as an effect of the ZnO buffer layers. The mobility in the ZnO epitaxial (main) layer was estimated to be 90 cm2/(V·s), which is reasonably high compared with those in ZnO layers grown by CVD processes. Photoluminescence at a low temperature (4.5 K) revealed a free A-exiton peak, and that at room temperature showed a strong band-edge peak with little deep-level luminescence.

  4. Polarized Raman spectroscopy study of NiSi film grown on Si(001) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Li; Ren, Yiming; Tang, Bo; Cheng, Xinhong; Zhang, Xuefei; Xu, Dapeng; Luo, Hijun; Huang, Yunmi [Wenzhou University, Department of Physics, Wenzhou (China)

    2009-11-15

    We report on the growth of NiSi film on Si(001) substrate with an orientation of NiSi[200]//Si[001]. Polarized Raman spectroscopy was used to assign the symmetry of the NiSi Raman peaks. Raman peaks at 213 cm{sup -1}, 295 cm{sup -1}, and 367 cm{sup -1} are assigned to be A{sub g} symmetry and peaks at 196 cm{sup -1}, and 254 cm{sup -1} are B{sub 3g} symmetry. (orig.)

  5. Comparison of the anthocyanin composition during ripening of Syrah grapes grown using organic or conventional agricultural practices.

    Science.gov (United States)

    Vian, Maryline Abert; Tomao, Valérie; Coulomb, Philippe Olivier; Lacombe, Jean Michel; Dangles, Olivier

    2006-07-26

    The anthocyanin composition of Syrah grapes harvested at different stages of ripening and produced using organic or conventional agriculture was studied. Samples of grapes were collected from veraison to full maturity in each plot, and the content in nine anthocyanins was determined by high-performance liquid chromatography with diode array detection. The total content in anthocyanins during ripening of the conventionally grown grapes was significantly higher compared to that found in the organic production. The accumulation of anthocyanins reached a maximum 28 days after veraison (in agreement with high temperature) and then decreased until harvest. In all samples, grapes from the conventional agriculture presented higher proportions of delphinidin, petunidin, malvidin, and acylated malvidin glucosides compared to grapes from organic agriculture. In contrast with other comparative studies of organically and conventionally grown plants, the results demonstrated a higher content in anthocyanins in conventionally grown grapes.

  6. Preparation of Surlyn films reinforced with cellulose nanofibres and feasibility of applying the transparent composite films for organic photovoltaic encapsulation

    Science.gov (United States)

    Lertngim, Anantaya; Phiriyawirut, Manisara; Wootthikanokkhan, Jatuphorn; Yuwawech, Kitti; Sangkhun, Weradesh; Kumnorkaew, Pisist; Muangnapoh, Tanyakorn

    2017-10-01

    This research concerns the development of Surlyn film reinforced with micro-/nanofibrillated celluloses (MFC) for use as an encapsulant in organic photovoltaic (OPV) cells. The aim of this work was to investigate the effects of fibre types and the mixing methods on the structure-properties of the composite films. Three types of cellulose micro/nanofibrils were prepared: the as-received MFC, the dispersed MFC and the esterified MFC. The fibres were mixed with Surlyn via an extrusion process, using two different mixing methods. It was found that the extent of fibre disintegration and tensile modulus of the composite films prepared by the master-batching process was superior to that of the composite system prepared by the direct mixing method. Using the esterified MFC as a reinforcement, compatibility between polymer and the fibre increased, accompanied with the improvement of the percentage elongation of the Surlyn composite film. The percentage of light transmittance of the Surlyn/MFC films was above 88, regardless of the fibre types and fibre concentrations. The water vapour transmission rate of the Surlyn/esterified MFC film was 65% lower than that of the neat Surlyn film. This contributed to the longer lifetime of the OPV encapsulated with the Surlyn/esterified MFC film.

  7. Hydroxyapatite thin films grown by pulsed laser deposition and matrix assisted pulsed laser evaporation: Comparative study

    Science.gov (United States)

    Popescu-Pelin, G.; Sima, F.; Sima, L. E.; Mihailescu, C. N.; Luculescu, C.; Iordache, I.; Socol, M.; Socol, G.; Mihailescu, I. N.

    2017-10-01

    Pulsed Laser Deposition (PLD) and Matrix Assisted Pulsed Laser Evaporation (MAPLE) techniques were applied for growing hydroxyapatite (HA) thin films on titanium substrates. All experiments were conducted in a reaction chamber using a KrF* excimer laser source (λ = 248 nm, τFWHM ≈ 25 ns). Half of the samples were post-deposition thermally treated at 500 °C in a flux of water vapours in order to restore crystallinity and improve adherence. Coating surface morphologies and topographies specific to the deposition method were evidenced by scanning electron, atomic force microscopy investigations and profilometry. They were shown to depend on deposition technique and also on the post-deposition treatment. Crystalline structure of the coatings evaluated by X-ray diffraction was improved after thermal treatment. Biocompatibility of coatings, cellular adhesion, proliferation and differentiation tests were conducted using human mesenchymal stem cells (MSCs). Results showed that annealed MAPLE deposited HA coatings were supporting MSCs proliferation, while annealed PLD obtained films were stimulating osteogenic differentiation.

  8. TiOx thin films grown on Pd(100) and Pd(111) by chemical vapor deposition

    Science.gov (United States)

    Farstad, M. H.; Ragazzon, D.; Grönbeck, H.; Strømsheim, M. D.; Stavrakas, C.; Gustafson, J.; Sandell, A.; Borg, A.

    2016-07-01

    The growth of ultrathin TiOx (0≤x≤2) films on Pd(100) and Pd(111) surfaces by chemical vapor deposition (CVD), using Titanium(IV)isopropoxide (TTIP) as precursor, has been investigated by high resolution photoelectron spectroscopy, low energy electron diffraction and scanning tunneling microscopy. Three different TiOx phases and one Pd-Ti alloy phase have been identified for both surfaces. The Pd-Ti alloy phase is observed at the initial stages of film growth. Density functional theory (DFT) calculations for Pd(100) and Pd(111) suggest that Ti is alloyed into the second layer of the substrate. Increasing the TTIP dose yields a wetting layer comprising Ti2 + species (TiOx, x ∼0.75). On Pd(100), this phase exhibits a mixture of structures with (3 × 5) and (4 × 5) periodicity with respect to the Pd(100) substrate, while an incommensurate structure is formed on Pd(111). Most importantly, on both surfaces this phase consists of a zigzag pattern similar to observations on other reactive metal surfaces. Further increase in coverage results in growth of a fully oxidized (TiO2) phase on top of the partially oxidized layer. Preliminary investigations indicate that the fully oxidized phase on both Pd(100) and Pd(111) may be the TiO2(B) phase.

  9. Structural characterization of niobium oxide thin films grown on SrTiO3 (111) and (La,Sr)(Al,Ta)O3 (111) substrates

    Science.gov (United States)

    Dhamdhere, Ajit R.; Hadamek, Tobias; Posadas, Agham B.; Demkov, Alexander A.; Smith, David J.

    2016-12-01

    Niobium oxide thin films have been grown by molecular beam epitaxy on SrTiO3 (STO) (111) and (La0.18Sr0.82)(Al0.59Ta0.41)O3 (LSAT) (111) substrates. Transmission electron microscopy (TEM) confirmed the formation of high quality films with coherent interfaces. Films grown with higher oxygen pressure on STO (111) resulted in a (110)-oriented NbO2 phase with a distorted rutile structure, which can be described as body-centered tetragonal. The a lattice parameter of NbO2 was determined to be ˜13.8 Å in good agreement with neutron diffraction results published in the literature. Films grown on LSAT (111) at lower oxygen pressure produced the NbO phase with a defective rock salt cubic structure. The NbO lattice parameter was determined to be a ≈ 4.26 Å. The film phase/structure identification from TEM was in good agreement with in situ x-ray photoelectron spectroscopy measurements that confirmed the dioxide and monoxide phases, respectively. The atomic structure of the NbO2/STO and NbO/LSAT interfaces was determined based on comparisons between high-resolution electron micrographs and image simulations.

  10. Data storage applications based on LiCoO2 thin films grown on Al2O3 and Si substrates

    Science.gov (United States)

    Svoukis, E.; Mihailescu, C. N.; Mai, V. H.; Schneegans, O.; Breza, K.; Lioutas, C.; Giapintzakis, J.

    2016-09-01

    In this study, LiCoO2 thin films were investigated for data storage applications based on scanning probe mediated approaches. LiCoO2, compared to other materials proposed for scanning probe mediated nanoscale patterning, is highly stable and exhibits reversible electrochemical surface modifications. LiCoO2 thin films have been grown by pulsed laser deposition on Al2O3 and Si substrates over a range of deposition temperatures. The crystal structure and the microstructure of the films has been inferred through in- and out-of-plane X-ray diffraction studies and high-resolution transmission electron microscopy, respectively. The influence of the film deposition temperature on the surface electrical properties of the LiCoO2 films is discussed along with the relevant mechanism of surface resistance modification.

  11. Microfabrication of a scanning probe with NV centers in a selectively grown diamond thin film through a xenon difluoride etching process

    Science.gov (United States)

    Zhu, Minjie; Li, Jinhua; Toda, Masaya; Ono, Takahito

    2017-12-01

    A scanning probe with nitrogen vacancy (NV) centers in diamond thin film was fabricated via a standard micro/nano electromechanical system process. The diamond thin film was selectively grown by microwave plasma enhanced chemical vapor deposition on a partially nucleated silicon surface. NV centers are embedded during the diamond growth with a pure nitrogen gas flow to the growth chamber. The existence of NV centers in the diamond thin film was confirmed by photoluminescence measurements. In addition, we found that a xenon difluoride (XeF2) etching process and anneal treatment have an influence on the existence of NV centers in the diamond. The fabricated scanning probe with NV centers in diamond thin film can be used as a magnetic scanning sensor. It is anticipated that the alternative method of selectively growing diamond thin film provides various diamond structures in diverse applications.

  12. Highly textured Gd2Zr2O7 films grown on textured Ni-5 at.%W substrates by solution deposition route: Growth, texture evolution, and microstructure dependency

    DEFF Research Database (Denmark)

    Yue, Zhao; Grivel, Jean-Claude; Napari, M.

    2012-01-01

    or crystallization in the thicker films. This work not only demonstrates a route for producing textured Gd2Zr2O7 buffer layers with dense structure directly on technical substrates, but also provides some fundamental understandings related to chemical solution derived films grown on metallic substrates.......Growth, texture evolution and microstructure dependency of solution derived Gd2Zr2O7 films deposited on textured Ni-5 at.%W substrates have been extensively studied. Influence of processing parameters, in particular annealing temperature and dwell time, as well as thickness effect on film texture...... the difference of interfacial energy along two directions in the anisotropic metallic substrate. Growth of Gd2Zr2O7 films displays an ultrafast kinetics under optimized conditions. Independency of sharp epitaxial (004) and polycrystalline (222) orientation is revealed from further synchrotron diffraction studies...

  13. The effect of sputtering gas pressure on the structure and optical properties of MgNiO films grown by radio frequency magnetron sputtering

    Science.gov (United States)

    Xie, Wuze; Jiao, Shujie; Wang, Dongbo; Gao, Shiyong; Wang, Jinzhong; Yu, Qingjiang; Li, Hongtao

    2017-05-01

    In this study, MgNiO thin films were grown on quartz substrates by radio frequency (RF) magnetron sputtering. The influence of different sputtering pressures on the crystalline and optical properties of MgNiO thin films has been studied. X-ray diffraction measurement indicates that the MgNiO films are cubic structure with (200) preferred orientation. UV-vis transmission spectra show that all the MgNiO thin films show more than 75% transmission at visible region, and the absorption edges of all thin films locate at solar-blind region (220 nm-280 nm). The lattice constant and Mg content of MgNiO samples were calculated using X-ray diffraction and transmission spectra data. The phase separation is observed both in the X-ray diffraction patterns and transmission spectra, and the phase separation is studied in detail based on the crystal growth theory and sputtering process.

  14. Electrical properties of ZnO thin films grown on a-plane sapphire substrates using catalytically generated high-energy H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, N.; Takeuchi, T.; Nagatomi, E.; Kato, T.; Umemoto, H.; Yasui, K., E-mail: kyasui@vos.nagaokaut.ac.jp

    2013-12-31

    The electrical properties of zinc oxide (ZnO) epitaxial films grown by chemical vapor deposition (CVD) using high-energy H{sub 2}O generated by H{sub 2}–O{sub 2} reactions on Pt nanoparticles were evaluated. High-energy ZnO precursors formed by the reaction between dimethylzinc gas molecules and H{sub 2}O molecules were supplied to the substrate surface. The ZnO epitaxial films were grown directly on a-plane sapphire (a-Al{sub 2}O{sub 3}) substrates at 773 K without any buffer layer. The electron mobility (μ{sub H}) at room temperature increased from 30 to 190 cm{sup 2}V{sup −1} s{sup −1} with increasing film thickness from 100 nm to 2800 nm. The μ{sub H} increased significantly with decreasing temperature to approximately 100–150 K, but it decreased at temperatures less than 100 K for films thicker than 500 nm. The μ{sub H} of the ZnO film (189 cm{sup 2}V{sup −1} s{sup −1}) at 290 K increased to 660 cm{sup 2}V{sup −1} s{sup −1} at 100 K. In contrast, μ{sub H} hardly changed with temperature for films thinner than 500 nm. According to a two-layer Hall-effect model, the μ{sub H} and electron concentration of the upper layer were corrected based on the above results, assuming that the degenerate layer had a thickness of 100 nm. - Highlights: • ZnO films were grown by CVD using reaction of high-energy H{sub 2}O and dimethylzinc gas. • Films were grown on a-plane sapphire substrates at 773 K. • ZnO film at 2.8 µm thick exhibited a large electron mobility of 189 cm{sup 2}/Vs at room temperature. • From the crystallinity and the electrical properties for various film thicknesses, the structure of the ZnO films was estimated. • The electron mobility and electron concentration of the upper layer were corrected according to a two-layer Hall-effect model.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-12-30

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

  16. Effect of N2O-doped buffer layer on the optical properties of ZnO films grown on glass substrates using high-energy H2O generated by catalytic reaction

    Science.gov (United States)

    Kanauchi, Shingo; Ohashi, Yuki; Ohishi, Koichiro; Katagiri, Hironori; Tamayama, Yasuhiro; Kato, Takahiro; Yasui, Kanji

    2016-02-01

    Improvement in the optical properties of ZnO films grown on glass substrates was investigated using a N2O-doped buffer layer inserted between the glass substrate and a ZnO film deposited by chemical vapor deposition (CVD). ZnO films were grown at 773 K using dimethylzinc (DMZn) and high-temperature H2O generated by catalytic reaction as zinc and oxygen sources, respectively. Crystal growth was enhanced for the ZnO film grown on the N2O-doped buffer layer, and the fluctuation in crystal orientation along the c-axis became less than that for a film grown directly on the glass substrate by CVD. The optical transmittance of the film in the wavelength range of 375-700 nm also increased with insertion of the buffer layer.

  17. High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded a-plane sapphire at low temperature

    Science.gov (United States)

    Jayah, Nurul Azzyaty; Yahaya, Hafizal; Mahmood, Mohamad Rusop; Terasako, Tomoaki; Yasui, Kanji; Hashim, Abdul Manaf

    2015-01-01

    Hydrothermal zinc oxide (ZnO) thick films were successfully grown on the chemical vapor deposition (CVD)-grown thick ZnO seed layers on a-plane sapphire substrates using the aqueous solution of zinc nitrate dehydrate (Zn(NO3)2). The use of the CVD ZnO seed layers with the flat surfaces seems to be a key technique for obtaining thick films instead of vertically aligned nanostructures as reported in many literatures. All the hydrothermal ZnO layers showed the large grains with hexagonal end facets and were highly oriented towards the c-axis direction. Photoluminescence (PL) spectra of the hydrothermal layers were composed of the ultraviolet (UV) emission (370 to 380 nm) and the visible emission (481 to 491 nm), and the intensity ratio of the former emission ( I UV) to the latter emission ( I VIS) changed, depending on both the molarity of the solution and temperature. It is surprising that all the Hall mobilities for the hydrothermal ZnO layers were significantly larger than those for their corresponding CVD seed films. It was also found that, for the hydrothermal films grown at 70°C to 90°C, the molarity dependences of I UV/ I VIS resembled those of mobilities, implying that the mobility in the film is affected by the structural defects. The highest mobility of 166 cm2/Vs was achieved on the hydrothermal film with the carrier concentration of 1.65 × 1017 cm-3 grown from the aqueous solution of 40 mM at 70°C.

  18. Physical and chemical composition of some walnut ( Juglans regia L genotypes grown in Turkey

    Directory of Open Access Journals (Sweden)

    Koyuncu, M. Ali

    2005-06-01

    Full Text Available Walnut ( Juglans regia L. samples were collected during the 2000 and 2001 harvests from different selections of trees grown in Turkey . Important physical and biochemical properties of fruit were examined in these walnut types. At the end of this study, 10 types were selected and nut and kernel properties, fatty acid composition and the proximate composition of these selections which are commonly grown in Turkey were evaluated. Physical properties are attributed to the quality criteria of nuts. Investigated genotypes showed good quality according to the test results. The total oil content ranged from 61.97 to 70.92 % while the crude protein ranged from 15.17 to 19.24 %. Ash ranged from 1.26 to 2.06 % while the moisture was found between 3.25-3.91 % of the kernel. The total carbohydrate was calculated as between 8.05-13.23 %. The oleic acid content of the oils ranged from 21.18 to 40.20% of the total fatty acids, while the linoleic acid content ranged from 43.94 to 60.12 % and the linolenic contents from 6.91 to11.52 %. It was found that palmitic acid was between 5.24 and 7.62 %, while stearic acid ranged from 2.56 to 3.67 %Las nueces ( Juglans regia L. fueron recolectadas durante los años 2000 y 2001 en diversos nogales seleccionados de Turquía y analizadas para determinar sus propiedades físicas y bioquímicas. Se seleccionaron 10 genotipos en los que fueron determinadas las propiedades de la cáscara y la semilla, la composición en ácidos grasos, así como su composición general. Las propiedades físicas son un atributo de calidad de las nueces. Los genotipos investigados mostraron una buena calidad de acuerdo a los resultados. El contenido total en aceite varió entre el 61.97 y el 70.92 % mientras que la proteína cruda fue del 15.17-19.24 %. La ceniza fue del 1.26-2.06 % y la humedad fue del 3.25-3.91 % de la semilla. Los carbohidratos totales fueron el 8.05-13.23 %. El contenido en ácido oleico fue del 21.18-40.20 % de los

  19. Characterization of WO3 Thin Films Grown on Silicon by HFMOD

    Directory of Open Access Journals (Sweden)

    Joel Díaz-Reyes

    2013-01-01

    modes of as-deposited WO3 and annealed at 500°C present clearly differences. WO3 band gap energy can be varied from 2.92 to 3.15 eV by annealing WO3 from 0 to 500°C as was obtained by transmittance measurements. The photoluminescence response of the as-deposited film presents three radiative transitions observed at 2.85, 2.41, and 2.04 eV that could be associated with oxygen vacancies; the first one is shifted to higher energies as the annealing temperature is increased due to the change of crystalline phase of the WO3.

  20. Formation of pyramid-like nanostructures in MBE-grown Si films on Si(001)

    Energy Technology Data Exchange (ETDEWEB)

    Galiana, N.; Martin, P.P.; Rodriguez-Canas, E.; Esteban-Betegon, F.; Alonso, M.; Ruiz, A. [CSIC, Instituto de Ciencia de Materiales de Madrid, Madrid (Spain); Garzon, L.; Ocal, C. [CSIC, Institut de Ciencia de Materials de Barcelona, Barcelona (Spain); Munuera, C. [CSIC, Instituto de Ciencia de Materiales de Madrid, Madrid (Spain); CSIC, Institut de Ciencia de Materials de Barcelona, Barcelona (Spain); Varela, M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2011-03-15

    The growth of Si homoepitaxial layers on Si(001) substrates by molecular beam epitaxy is analyzed for a set of growth conditions in which diverse nanometer-scale features develop. Using Si substrates prepared by exposure to HF vapor and annealing in ultra-high vacuum, a rich variety of surface morphologies is found for different deposited layer thicknesses and substrate temperatures in a reproducible way, showing a critical dependence on both. Arrays of 3D islands (truncated pyramids), percolated ridge networks, and square pit (inverted pyramid) distributions are observed. We analyze the obtained arrangements and find remarkable similarities to other semiconductor though heteroepitaxial systems. The nanoscale entities (islands or pits) display certain self assembly and ordering, concerning size, shape, and spacing. Film growth sequence follows the 'islands-coalescence-2D growth' pathway, eventually leading to optimum flat morphologies for high enough thickness and temperature. (orig.)

  1. ZnO films grown by MOCVD on GaAs substrates: Effects of a Zn buffer deposition on interface, structural and morphological properties

    Science.gov (United States)

    Agouram, S.; Martínez-Tomás, M. C.; Muñoz-Sanjosé, V.

    2009-04-01

    Integration of ZnO with the well-developed GaAs technology presents several aspects that need to be previously analyzed and considered. The large lattice mismatch between ZnO and GaAs and its different crystallographic structure lead to many structural defects. In addition, their potential chemical reactivity is another source of complexity and an academic challenge. Recently some interesting contributions on this subject have been carried out by Liu and co-workers. As an additional step to the knowledge of the ZnO/GaAs heterostructure, we have deepened on the study of the morphology and orientation of ZnO thin films grown by atmospheric pressure metal-organic chemical vapour deposition (AP-MOCVD) on GaAs(1 0 0) and GaAs(1 1 1)A substrates with and without a Zn buffer pre-deposition on them. The analysis has been made as a function of growth temperature and precursors ratio. Structural, morphological and compositional characterizations have been made by X-ray diffraction (XRD), high-resolution X-ray diffraction (HRXRD), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX) and X-ray photoemission spectroscopy (XPS). ZnO layers present an out-of-plane (0 0 0 1) preferred orientation, while the in-plane orientation has a random distribution. The layers are constituted by large tilted columnar grains with a top angle of around 55° indicating that the planes which constitute the conic heads are the {1 0 1¯ 1} ones. ZnO films grown after a previous Zn deposition exhibit a less compact morphology. In some cases and depending on growth conditions, interfacial processes with crystallization of extrinsic phases have been observed by XRD, revealing the presence of a body centred tetragonal phase of Zn 3As 2. In order to get an insight into these interfacial effects, EDX on cross-sectional views of the interface has been carried out. Strain measurements indicate a tensile nature of the biaxial stress, which is reduced by a factor two when the Zn

  2. Chemical Composition and Allelopathic Potential of Essential Oils from Citharexylum spinosum L. Grown in Tunisia.

    Science.gov (United States)

    El Ayeb-Zakhama, Asma; Sakka-Rouis, Lamia; Flamini, Guido; Ben Jannet, Hichem; Harzallah-Skhiri, Fethia

    2017-04-01

    Citharexylum spinosum L. (Verbenaceae) also known as Citharexylum quadrangulare Jacq. or Citharexylum fruticosum L. is an exotic tree introduced many years ago in Tunisia, specially used as a street and park ornamental tree. Essential oils (EOs) were obtained by hydrodistillation of the different parts (roots, stems, leaves, flowers and fruits; drupes) collected from trees grown in the area of Monastir (Tunisia). In total, 84 compounds, representing 90.1 - 98.4% of the whole oil composition, were identified by GC-FID and GC/MS analyses. The root EO was distinguished by its high content in monoterpene hydrocarbons (α-phellandrene; 30.8%) whereas that obtained from stems was dominated by sesquiterpene hydrocarbons (cuparene; 16.4%). The leaf oil was rich in an apocarotenoid derivative (hexahydrofarnesylacetone; 26%) and an aliphatic hydrocarbon (nonadecane; 14.5%). Flowers oil was rich in esters (2-phenylethyl benzoate; 33.5%). Finally, drupes oil was rich in oxygenated sesquiterpenes (β-eudesmol; 33.1%). Flowers oil showed a significant phytotoxic effect against lettuce seeds germination, it induces a total inhibition when tested at 1 mg/ml. Root and shoot elongation seemed to be more affected than germination. The inhibition of the shoot length varied from 3.6% to 100% and that of the root from 16.1% to 100%. The highest inhibition of 100% was detected for flower oil tested at 1 mg/ml. Our in vitro studies suggest a possible and new alternative use of C. spinosum EOs in herbicidal formulations, further experiments involving field conditions are necessary to confirm its herbicidal potential. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  3. Microstructure and tribological performance of self-lubricating diamond/tetrahedral amorphous carbon composite film

    Science.gov (United States)

    Chen, Xinchun; Peng, Zhijian; Yu, Xiang; Fu, Zhiqiang; Yue, Wen; Wang, Chengbiao

    2011-02-01

    In order to smooth the rough surface and further improve the wear-resistance of coarse chemical vapor deposition diamond films, diamond/tetrahedral amorphous carbon composite films were synthesized by a two-step preparation technique including hot-filament chemical vapor deposition for polycrystalline diamond (PCD) and subsequent filtered cathodic vacuum arc growth for tetrahedral amorphous carbon (ta-C). The microstructure and tribological performance of the composite films were investigated by means of various characterization techniques. The results indicated that the composite films consisted of a thick well-grained diamond base layer with a thickness up to 150 μm and a thin covering ta-C layer with a thickness of about 0.3 μm, and sp3-C fraction up to 73.93%. Deposition of a smooth ta-C film on coarse polycrystalline diamond films was proved to be an effective tool to lower the surface roughness of the polycrystalline diamond film. The wear-resistance of the diamond film was also enhanced by the self-lubricating effect of the covering ta-C film due to graphitic phase transformation. Under dry pin-on-disk wear test against Si3N4 ball, the friction coefficients of the composite films were much lower than that of the single PCD film. An extremely low friction coefficient (∼0.05) was achieved for the PCD/ta-C composite film. Moreover, the addition of Ti interlayer between the ta-C and the PCD layers can further reduce the surface roughness of the composite film. The main wear mechanism of the composite films was abrasive wear.

  4. Functional chitosan-based grapefruit seed extract composite films for applications in food packaging technology

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Y.M. [Department of Mechanical Engineering, National University of Singapore (Singapore); Lim, S.H.; Tay, B.Y. [Forming Technology Group, Singapore Institute of Manufacturing Technology (Singapore); Lee, M.W. [Food Innovation and Resource Centre, Singapore Polytechnic (Singapore); Thian, E.S., E-mail: mpetes@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore (Singapore)

    2015-09-15

    Highlights: • Chitosan-based grapefruit seed extract (GFSE) films were solution casted. • GFSE was uniformly dispersed within all chitosan film matrices. • All chitosan-based composite films showed remarkable transparency. • Increasing amounts of GFSE incorporated increased the elongation at break of films. • Chitosan-based GFSE composite films inhibited the proliferation of fungal growth. - Abstract: Chitosan-based composite films with different amounts of grapefruit seed extract (GFSE) (0.5, 1.0 and 1.5% v/v) were fabricated via solution casting technique. Experimental results showed that GFSE was uniformly dispersed within all chitosan film matrices. The presence of GFSE made the films more amorphous and tensile strength decreased, while elongation at break values increased as GFSE content increased. Results from the measurement of light transmission revealed that increasing amounts of GFSE (from 0.5 to 1.5% v/v) did not affect transparency of the films. Furthermore, packaging of bread samples with chitosan-based GFSE composite films inhibited the proliferation of fungal growth as compared to control samples. Hence, chitosan-based GFSE composite films have the potential to be a useful material in the area of food technology.

  5. Characterization of 4H Silicon Carbide Films Grown by Solvent-Laser Heated Floating Zone

    Science.gov (United States)

    Woodworth, Andrew, A; Sayir, Ali; Neudeck, Philip, G; Raghothamachar, Balaji; Dudley, Michael

    2012-01-01

    Commercially available bulk silicon carbide (SiC) has a high number (>2000/sq cm) of screw dislocations (SD) that have been linked to degradation of high-field power device electrical performance properties. Researchers at the NASA Glenn Research Center have proposed a method to mass-produce significantly higher quality bulk SiC. In order for this bulk growth method to become reality, growth of long single crystal SiC fibers must first be achieved. Therefore, a new growth method, Solvent-Laser Heated Floating Zone (Solvent-LHFZ), has been implemented. While some of the initial Solvent-LHFZ results have recently been reported, this paper focuses on further characterization of grown crystals and their growth fronts. To this end, secondary ion mass spectroscopy (SIMS) depth profiles, cross section analysis by focused ion beam (FIB) milling and mechanical polishing, and orientation and structural characterization by x-ray transmission Laue diffraction patterns and x-ray topography were used. Results paint a picture of a chaotic growth front, with Fe incorporation dependant on C concentration.

  6. Polymer−metal organic framework composite films as affinity layer for capacitive sensor devices

    NARCIS (Netherlands)

    Sachdeva, S.; Gravesteijn, Dirk J; Soccol, D.; Kapteijn, F.; Sudhölter, E.J.R.; Gascon, J.; Smet, de L.C.P.M.

    2016-01-01

    We report a simple method for sensor development using polymer-MOF composite films. Nanoparticles of NH2-MIL-53(Al) dispersed in a Matrimid polyimide were applied as a thin film on top of capacitive sensor devices with planar electrodes. These drop-cast films act as an affinity layer. Sensing

  7. Highly transparent and reproducible nanocrystalline ZnO and AZO thin films grown by room temperature pulsed-laser deposition on flexible Zeonor plastic substrates

    Science.gov (United States)

    Inguva, Saikumar; Vijayaraghavan, Rajani K.; McGlynn, Enda; Mosnier, Jean-Paul

    2015-09-01

    Zeonor plastics are highly versatile due to exceptional optical and mechanical properties which make them the choice material in many novel applications. For potential use in flexible transparent optoelectronic applications, we have investigated Zeonor plastics as flexible substrates for the deposition of highly transparent ZnO and AZO thin films. Films were prepared by pulsed laser deposition at room temperature in oxygen ambient pressures of 75, 150 and 300 mTorr. The growth rate, surface morphology, hydrophobicity and the structural, optical and electrical properties of as-grown films with thicknesses ˜65-420 nm were recorded for the three oxygen pressures. The growth rates were found to be highly linear both as a function of film thickness and oxygen pressure, indicating high reproducibility. All the films were optically smooth, hydrophobic and nanostructured with lateral grain shapes of ˜150 nm wide. This was found compatible with the deposition of condensed nanoclusters, formed in the ablation plume, on a cold and amorphous substrate. Films were nanocrystalline (wurtzite structure), c-axis oriented, with average crystallite size ˜22 nm for ZnO and ˜16 nm for AZO. In-plane compressive stress values of 2-3 GPa for ZnO films and 0.5 GPa for AZO films were found. Films also displayed high transmission greater than 95% in some cases, in the 400-800 nm wavelength range. The low temperature photoluminescence spectra of all the ZnO and AZO films showed intense near band edge emission. A considerable spread from semi-insulating to n-type conductive was observed for the films, with resistivity ˜103 Ω cm and Hall mobility in 4-14 cm2 V-1 s-1 range, showing marked dependences on film thickness and oxygen pressure. Applications in the fields of microfluidic devices and flexible electronics for these ZnO and AZO films are suggested.

  8. Emerging photoluminescence from bilayer large-area 2D MoS2 films grown by pulsed laser deposition on different substrates

    Science.gov (United States)

    Barvat, Arun; Prakash, Nisha; Satpati, Biswarup; Singha, Shib Shankar; Kumar, Gaurav; Singh, Dilip K.; Dogra, Anjana; Khanna, Suraj P.; Singha, Achintya; Pal, Prabir

    2017-07-01

    We report the growth of continuous large area bilayer films of MoS2 on different substrates by pulsed laser deposition (PLD). The growth parameters for PLD were modified in such a way that results in bilayer 2D-MoS2 films on both c-Al2O3 (0001) (sapphire) and SiO2/Si (SO) substrates. The bilayer large area crystalline nature of growth in the 2 H-phase is determined by Raman spectroscopy. Cross-sectional transmission electron microscopy confirms the distinct thinnest ordered layered structure of MoS2. Chemical analysis reveals an almost stoichiometric 2 H-phase on both the substrates. The photoluminescence intensities of both the films match very well with those of the corresponding exfoliated flakes, as well as chemical vapor deposited (CVD) films as reported in the literature. The in-situ post growth annealing with optimal film thickness acts as a solid phase epitaxy process which provides continuous crystalline layers with a smooth interface and regulates the photoluminescence properties. In contrast, the PLD grown MoS2 monolayer shows poor crystalline quality and non-uniform coverage compared to that with the exfoliated and CVD grown films.

  9. Observation of low resistivity and high mobility in Ga doped ZnO thin films grown by buffer assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ajimsha, R.S., E-mail: ajimsha@gmail.com [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Das, Amit K.; Misra, P.; Joshi, M.P.; Kukreja, L.M. [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Kumar, R.; Sharma, T.K.; Oak, S.M. [Semiconductor Physics & Devices Lab., Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2015-07-25

    Highlights: • Ga doped ZnO thin films were grown using buffer assisted pulsed laser deposition. • Lowest resistivity ∼5.1 × 10{sup −5} Ω cm with a mobility of ∼41.9 cm{sup 2}/V s was observed. • Buffer assisted growth methodology maintains relatively good crystalline quality. • This plays a key role in decreasing the resistivity of to the aforementioned value. • This resistivity value, to the best of our knowledge is the lowest so far in ZnO. - Abstract: We have grown Ga doped ZnO (GZO) thin films at moderate temperatures with Ga concentrations in the range varying from 0.25 to 3 at.% on sapphire substrates using buffer assisted pulsed laser deposition. Room temperature resistivity measured was ∼5.1 × 10{sup −5} Ω cm with a electron mobility of ∼41.9 cm{sup 2}/V s for an optimum Ga concentration of ∼0.75 at.% in the GZO films. Buffer assisted growth methodology maintains relatively good crystalline quality of the GZO thin films, thereby improving the electron mobility even at high dopant concentrations. This plays a key role in decreasing the resistivity of GZO films to the aforementioned value, which to the best of our knowledge is the lowest so far. These highly conducting GZO thin films with good mobility are potential candidates for transparent conducting oxide (TCO) applications in various optoelectronic devices.

  10. MOCVD Grown InP and Related Thin Films on Silicon Substrates for Electron and Photonic Devices Applications

    Science.gov (United States)

    Zhong, Zhenyu

    Heterogeneous integration of III-V compound semiconductor with silicon is attracting renewed attention in recent years due to its potential in electronic and photonic applications. For electronic applications, a robust integration allows low-voltage and high-speed III-V based transistors to couple with mature silicon-based technologies for functional circuit blocks. Several successful demonstrations have been achieved by molecular beam epitaxy (MBE). In regard to photonic applications, silicon photonics is an important area of research with its possible replacement of copper interconnects. The well-developed III-V photonic devices can be utilized on a silicon platform if a seamless integration can be realized. This concept has been extensively demonstrated by wafer bonding, whereas the manufacturing complexity, reliability and yield are main challenges in this transfer technique. In this thesis, demonstration of heterogeneous integration of III-V based electron and photonic devices on silicon substrates is described, using Metal organic chemical vapor deposition (MOCVD), which is considered more compatible with CMOS processes with good potential for wafer level manufacturing. In this work, InP thin films with smooth surface morphology were firstly achieved by introducing thin GaAs buffer layers. The GaAs buffer was optimized based on the surface morphology, crystalline quality and in situ RAS signal. The total thickness of the buffer layer was finally reduced to 1.2mum by trimming the GaAs buffers as a thin buffer is more desirable for process integration. On top of the thin InP buffer layers, high performance metamorphic high electron mobility transistors (mHEMTs) have been demonstrated for the first time. To implement photonic devices on the buffers, the epitaxial films quality was further improved utilizing novel post-treatment techniques, including thermal process and strained layers for defects reduction. InGaAs p-i-n photodetectors lattice-matched to In

  11. Effect of BST film thickness on the performance of tunable interdigital capacitors grown by MBE

    Science.gov (United States)

    Meyers, Cedric J. G.; Freeze, Christopher R.; Stemmer, Susanne; York, Robert A.

    2017-12-01

    Voltage-tunable, interdigital capacitors (IDCs) were fabricated on Ba0.29Sr0.71TiO3 grown by hybrid molecular beam epitaxy (MBE). In this growth technique, we utilize the metal-organic precursor titanium tetraisopropoxide rather than solid-source Ti as with conventional MBE. Two samples of varying BaxSr(1-x)TiO3 (BST) thicknesses were fabricated and analyzed. High-quality, epitaxial Pt electrodes were deposited by sputtering from a high-purity Pt target at 825 °C. The Pt electrodes were patterned and etched by argon ion milling, passivated with reactively sputtered SiO2, and then metallized with lift-off Ti/Au. The fabricated devices consisted of two-port IDCs embedded in ground-signal-ground, coplanar waveguide (CPW) transmission lines to enable radio-frequency (RF) probing. The sample included open and thru de-embedding structures to remove pad and CPW parasitic impedances. Two-port RF scattering (S) parameters were measured from 100 MHz to 40 GHz while DC bias was stepped from 0 V to 100 V. The IDCs exhibit a high zero-bias radio-frequency (RF) quality factor (Q) approaching 200 at 1 GHz and better than 2.3:1 capacitance tuning for the 300-nm-thick sample. Differences in the Q(V) and C(V) response with varying thicknesses indicate that unknown higher order material phenomena are contributing to the loss and tuning characteristics of the material.

  12. A study on the sensing of NO(sub2) and O(sub2) utilizing ZnO films grown by aerosol spray pyrolysis

    CSIR Research Space (South Africa)

    Mhlongo, GH

    2015-07-01

    Full Text Available The present paper addresses the preparation and characterization of ZnO nanostructured thin films obtained using aerosol spray pyrolysis method at different deposition periods. Aiming at understanding the chemical composition, structural...

  13. Role of the substrate on the magnetic anisotropy of magnetite thin films grown by ion-assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Pilar, E-mail: pilar.prieto@uam.es [Dpto. Física Aplicada M-12, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Prieto, José Emilio [Centro de Microanálisis de Materiales (CMAM) and Dpto. De Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Gargallo-Caballero, Raquel; Marco, José Francisco; Figuera, Juan de la [Instituto de Química Física “Rocasolano”, CSIC, 28006 Madrid (Spain)

    2015-12-30

    Graphical abstract: - Highlights: • The magnetic anisotropy of magnetite thin films is controlled by the substrate induced microstructure. • Single-crystal oxide substrates induce fourfold in-plane magnetic anisotropy • MgO and SrTiO{sub 3} substrates show the same magnetic behavior despite its different mismatch with Fe{sub 3}O{sub 4} films. • Silicon and glass substrates induce in-plane magnetic isotropy and uniaxial anisotropy, respectively. - Abstract: Magnetite (Fe{sub 3}O{sub 4}) thin films were deposited on MgO (0 0 1), SrTiO{sub 3} (0 0 1), LaAlO{sub 3} (0 0 1) single crystal substrates as well on as silicon and amorphous glass in order to study the effect of the substrate on their magnetic properties, mainly the magnetic anisotropy. We have performed a structural, morphological and compositional characterization by X-ray diffraction, atomic force microscopy and Rutherford backscattering ion channeling in oxygen resonance mode. The magnetic anisotropy has been investigated by vectorial magneto-optical Kerr effect. The results indicate that the magnetic anisotropy is especially influenced by the substrate-induced microstructure. In-plane isotropy and uniaxial anisotropy behavior have been observed on silicon and glass substrates, respectively. The transition between both behaviors depends on grain size. For LaAlO{sub 3} substrates, in which the lattice mismatch between the Fe{sub 3}O{sub 4} films and the substrate is significant, a weak in-plane fourfold magnetic anisotropy is induced. However when magnetite is deposited on MgO (0 0 1) and SrTiO{sub 3} (0 0 1) substrates, a well-defined fourfold in-plane magnetic anisotropy is observed with easy axes along [1 0 0] and [0 1 0] directions. The magnetic properties on these two latter substrates are similar in terms of magnetic anisotropy and coercive fields.

  14. Bipolar resistive switching in room temperature grown disordered vanadium oxide thin-film devices

    Science.gov (United States)

    Wong, Franklin J.; Sriram, Tirunelveli S.; Smith, Brian R.; Ramanathan, Shriram

    2013-09-01

    We demonstrate bipolar switching with high OFF/ON resistance ratios (>104) in Pt/vanadium oxide/Cu structures deposited entirely at room temperature. The SET (RESET) process occurs when negative (positive) bias is applied to the top Cu electrode. The vanadium oxide (VOx) films are amorphous and close to the vanadium pentoxide stoichiometry. We also investigated Cu/VOx/W structures, reversing the position of the Cu electrode, and found the same polarity dependence with respect to the top and bottom electrodes, which suggests that the bipolar nature is linked to the VOx layer itself. Bipolar switching can be observed at 100 °C, indicating that it not due to a temperature-induced metal-insulator transition of a vanadium dioxide second phase. We discuss how ionic drift can lead to the bipolar electrical behavior of our junctions, similar to those observed in devices based on several other defective oxides. Such low-temperature processed oxide switches could be of relevance to back-end or package integration processing schemes.

  15. Uniform hexagonal graphene flakes and films grown on liquid copper surface.

    Science.gov (United States)

    Geng, Dechao; Wu, Bin; Guo, Yunlong; Huang, Liping; Xue, Yunzhou; Chen, Jianyi; Yu, Gui; Jiang, Lang; Hu, Wenping; Liu, Yunqi

    2012-05-22

    Unresolved problems associated with the production of graphene materials include the need for greater control over layer number, crystallinity, size, edge structure and spatial orientation, and a better understanding of the underlying mechanisms. Here we report a chemical vapor deposition approach that allows the direct synthesis of uniform single-layered, large-size (up to 10,000 μm(2)), spatially self-aligned, and single-crystalline hexagonal graphene flakes (HGFs) and their continuous films on liquid Cu surfaces. Employing a liquid Cu surface completely eliminates the grain boundaries in solid polycrystalline Cu, resulting in a uniform nucleation distribution and low graphene nucleation density, but also enables self-assembly of HGFs into compact and ordered structures. These HGFs show an average two-dimensional resistivity of 609 ± 200 Ω and saturation current density of 0.96 ± 0.15 mA/μm, demonstrating their good conductivity and capability for carrying high current density.

  16. Crystalline Fe films grown on non-polar GaN: theory and experiment

    Science.gov (United States)

    Erwin, Steven; Gao, Cunxu; Roder, Claudia; Laehnemann, Jonas; Brandt, Oliver

    2012-02-01

    We report an unexpected mechanism by which single crystals of Fe grow epitaxially on M-plane GaN substrates despite having a different crystal structure and strongly mismatched lattice constant. A simple model is proposed in which one material tilts out of the interface plane to create a coincidence-site lattice that balances two competing geometrical criteria---low residual strain and short coincidence-lattice period. We apply this model, along with complementary first-principles total energy calculations, to the interface formed by molecular-beam epitaxy of cubic Fe on hexagonal GaN and find excellent agreement between theory and experiment. The success of this model also suggests a strategy for growing non-polar GaN films on a substrate material with a suitably chosen Miller index. One very promising material is Si, which is already in widespread use as a flat substrate for GaN/Si epitaxy despite high dislocation densities. The next talk will present our predictions of the most promising Si(hhk) substrates for growing non-polar GaN with high crystalline quality.

  17. Preparation of ZnO nanoribbon–MWCNT composite film and its ...

    Indian Academy of Sciences (India)

    The composite film successfully removed the Escherichiacoli bacteria from water and destroyed the bacteria retained on its surface due to the antibacterial action of ZnO NRs. The absorption of thermal IR radiation by the composite film was studied by thermography, which can be useful in IR camouflageapplications.

  18. Influence of high loading of cellulose nanocrystals in polyacrylonitrile composite films

    Science.gov (United States)

    Jeffrey Luo; Huibin Chang; Amir A. Bakhtiary Davijani; H. Clive Liu; Po-Hsiang Wang; Robert J. Moon; Satish Kumar

    2017-01-01

    Polyacrylonitrile-co-methacrylic acid (PAN-co-MAA) and cellulose nanocrystal (CNC) composite films were produced with up to 40 wt% CNC loading through the solution casting method. The rheological properties of the solution/suspensions and the structural, optical, thermal, and mechanical properties of the resulting films were investigated. The viscosity of the composite...

  19. Vapor Grown Carbon Fiber/Polydicyclopentadiene Composites: Shapeable Pastes to Make Composite Tooling and Plasma Erosion-Resistant Parts

    National Research Council Canada - National Science Library

    Pittman, Charles

    2002-01-01

    Vapor grown carbon nanofibers (VGCF) with 60-250nm diameters and 10 to 80 micrometers lengths were blended with the nonpolar organic monomer, dicyclopentadiene, to create liquid dispersions or pastes (based on the wt% fiber used...

  20. Evaluation of Fatty Acid and Amino Acid Compositions in Okra (Abelmoschus esculentus) Grown in Different Geographical Locations

    OpenAIRE

    Sami, Rokayya; Lianzhou, Jiang; Yang, Li; Ma, Ying; Jing, Jing

    2013-01-01

    Okra has different uses as a food and a remedy in traditional medicine. Since it produces many seeds, distribution of the plant is also quite easy. Although seed oil yield is low (4.7%), since the linoleic acid composition of the seed oil is quiet high (67.5%), it can still be used as a source of (UNSAT) unsaturated fatty acids. In this study, samples of okra grown in four different locations were analyzed to measure fatty acid and amino acid compositions. The content of the lipid extraction ...

  1. Temperature-dependent photoluminescence and mechanism of CdS thin film grown on Si nanoporous pillar array

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ling Ling [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China); College of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China); Li, Yan Tao [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China); School of Material Science and Engineering, Henan University of Technology, Zhengzhou 454052 (China); Hu, Chu Xiong [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China); Li, Xin Jian, E-mail: lixj@zzu.edu.cn [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China)

    2015-09-15

    Highlights: • CdS/silicon nanoporous pillar array (CdS/Si-NPA) was prepared by a CBD method. • The PL spectrum of CdS/Si-NPA was measured at different temperatures, from 10 to 300 K. • The PL spectrum was composed of four emission bands, obeying different mechanisms. • The PL degradation with temperature was due to phonon-induced escape of carriers. - Abstract: Si-based cadmium sulfide (CdS) is a prospective semiconductor system in constructing optoelectronic nanodevices, and this makes the study on the factors which may affect its optical and electrical properties be of special importance. Here we report that CdS thin film was grown on Si nanoporous pillar array (Si-NPA) by a chemical bath deposition method, and the luminescent properties of CdS/Si-NPA as well as its mechanism were studied by measuring and analyzing its temperature-dependent photoluminescence (PL) spectrum. The low-temperature measurement disclosed that the PL spectrum of CdS/Si-NPA could be decomposed into four emission bands, a blue band, a green band, a red band and an infrared band. The blue band was due to the luminescence from Si-NPA substrate, and the others originate from the CdS thin film. With temperature increasing, the peak energy, PL intensity and peak profile shape for the PL bands from CdS evolves differently. Through theoretical and fitting analyses, the origins of the green, red and infrared band are attributed to the near band-edge emission, the radiative recombination from surface defects to Cd vacancies and those to S interstitials, respectively. The cause of PL degradation is due to the thermal quenching process, a phonon-induced electron escape but with different activation energies. These results might provide useful information for optimizing the preparing parameters to promote the performance of Si-based CdS optoelectronic devices.

  2. Formation of magnetically anisotropic composite films at low magnetic fields

    Science.gov (United States)

    Ghazi Zahedi, Maryam; Ennen, Inga; Marchi, Sophie; Barthel, Markus J.; Hütten, Andreas; Athanassiou, Athanassia; Fragouli, Despina

    2017-04-01

    We present a straightforward two-step technique for the fabrication of poly (methyl methacrylate) composites with embedded aligned magnetic chains. First, ferromagnetic microwires are realized in a poly (methyl methacrylate) solution by assembling iron nanoparticles in a methyl methacrylate solution under heat in an external magnetic field of 160 mT. The simultaneous thermal polymerization of the monomer throughout the wires is responsible for their permanent linkage and stability. Next, the polymer solution containing the randomly dispersed microwires is casted on a solid substrate in the presence of a low magnetic field (20-40 mT) which induces the final alignment of the microwires into long magnetic chains upon evaporation of the solvent. We prove that the presence of the nanoparticles assembled in the form of microwires is a key factor for the formation of the anisotropic films under low magnetic fields. In fact, such low fields are not capable of driving and assembling dispersed magnetic nanoparticles in the same type of polymer solutions. Hence, this innovative approach can be utilized for the synthesis of magnetically anisotropic nanocomposite films at low magnetic fields.

  3. Detection of Carbon Monoxide Using Polymer-Carbon Composite Films

    Science.gov (United States)

    Homer, Margie L.; Ryan, Margaret A.; Lara, Liana M.

    2011-01-01

    A carbon monoxide (CO) sensor was developed that can be incorporated into an existing sensing array architecture. The CO sensor is a low-power chemiresistor that operates at room temperature, and the sensor fabrication techniques are compatible with ceramic substrates. Sensors made from four different polymers were tested: poly (4-vinylpryridine), ethylene-propylene-diene-terpolymer, polyepichlorohydrin, and polyethylene oxide (PEO). The carbon black used for the composite films was Black Pearls 2000, a furnace black made by the Cabot Corporation. Polymers and carbon black were used as received. In fact, only two of these sensors showed a good response to CO. The poly (4-vinylpryridine) sensor is noisy, but it does respond to the CO above 200 ppm. The polyepichlorohydrin sensor is less noisy and shows good response down to 100 ppm.

  4. An amorphous-to-crystalline phase transition within thin silicon films grown by ultra-high-vacuum evaporation and its impact on the optical response

    Science.gov (United States)

    Orapunt, Farida; Tay, Li-Lin; Lockwood, David J.; Baribeau, Jean-Marc; Noël, Mario; Zwinkels, Joanne C.; O'Leary, Stephen K.

    2016-02-01

    A number of thin silicon films are deposited on crystalline silicon, native oxidized crystalline silicon, and optical quality fused quartz substrates through the use of ultra-high-vacuum evaporation at growth temperatures ranging from 98 to 572 °C. An analysis of their grazing incidence X-ray diffraction and Raman spectra indicates that a phase transition, from amorphous-to-crystalline, occurs as the growth temperature is increased. Through a peak decomposition process, applied to the Raman spectroscopy results, the crystalline volume fractions associated with these samples are plotted as a function of the growth temperature for the different substrates considered. It is noted that the samples grown on the crystalline silicon substrates have the lowest crystallanity onset temperature, whereas those grown on the optical quality fused quartz substrates have the highest crystallanity onset temperature; the samples grown on the native oxidized crystalline silicon substrates have a crystallanity onset temperature between these two limits. These resultant dependencies on the growth temperature provide a quantitative means of characterizing the amorphous-to-crystalline phase transition within these thin silicon films. It is noted that the thin silicon film grown on an optical quality fused quartz substrate at 572 °C, possessing an 83% crystalline volume fraction, exhibits an optical absorption spectrum which is quite distinct from that associated with the other thin silicon films. We suggest that this is due to the onset of sufficient long-range order in the film for wave-vector conservation to apply, at least partially. Finally, we use a semi-classical optical absorption analysis to study how this phase transition, from amorphous-to-crystalline, impacts the spectral dependence of the optical absorption coefficient.

  5. Influence of deposition temperature on the structural and morphological properties of Be{sub 3}N{sub 2} thin films grown by reactive laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Chale-Lara, F., E-mail: fabio_chale@yahoo.com.mx [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Apartado Postal 2681, Ensenada, Baja California, C.P. 22860 (Mexico); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Apartado Postal 14, Ensenada CP 22860, Baja California (Mexico); Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, Unidad Altamira, Km. 14.5 Carretera Tampico-Puerto Industrial, Altamira, Tamaulipas (Mexico); Farias, M.H.; De la Cruz, W. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Apartado Postal 14, Ensenada CP 22860, Baja California (Mexico); Zapata-Torres, M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, Legaria 694, Col. Irrigacion, Del. Miguel Hidalgo, Mexico D.F. (Mexico)

    2010-10-01

    Be{sub 3}N{sub 2} thin films have been grown on Si(1 1 1) substrates using the pulsed laser deposition method at different substrate temperatures: room temperature (RT), 200 deg. C, 400 deg. C, 600 deg. C and 700 deg. C. Additionally, two samples were deposited at RT and were annealed after deposition in situ at 600 deg. C and 700 deg. C. In order to obtain the stoichiometry of the samples, they have been characterized in situ by X-ray photoelectron (XPS) and reflection electron energy loss spectroscopy (REELS). The influence of the substrate temperature on the morphological and structural properties of the films was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The results show that all prepared films presented the Be{sub 3}N{sub 2} stoichiometry. Formation of whiskers with diameters of 100-200 nm appears at the surface of the films prepared with a substrate temperature of 600 deg. C or 700 deg. C. However, the samples grown at RT and annealed at 600 deg. C or 700 deg. C do not show whiskers on the surface. The average root mean square (RMS) roughness and the average grain size of the samples grown with respect the substrate temperature is presented. The films grown with a substrate temperature between the room temperature to 400 deg. C, and the sample annealed in situ at 600 deg. C were amorphous; while the {alpha}Be{sub 3}N{sub 2} phase was presented on the samples with a substrate temperature of 600 deg. C, 700 deg. C and that deposited with the substrate at RT and annealed in situ at 700 deg. C.

  6. Thin metal film-polymer composite for efficient optoacoustic generation (Conference Presentation)

    Science.gov (United States)

    Lee, Taehwa; Guo, L. Jay

    2016-03-01

    Photoacoustic (PA) conversion of metal film absorbers is known to be inefficient because of their low thermal expansion and high light reflectance, as compared to polymeric materials containing light absorbing fillers. Specifically, the PA signal for metal films is typically an order of magnitude lower than those for PDMS-based composites consisting of carbon materials such as carbon blacks, carbon nanotubes, and carbon fibers. However, the carbon-PDMS composites have several disadvantages, e.g., difficulty in controlling film thickness, aggregation of the carbon fillers, and poor patternablility. To overcome these issues and achieve comparable PA amplitudes, a polymer-metal film composite was developed consisting of a thin metal absorber and adjacent transparent polymer layers. The proposed structure shows efficient PA conversion. The measured PA amplitude of the metal film composite is an order of magnitude higher than that of metal-only samples, and comparable to those of the carbon-PDMS composites. The enhanced PA conversion is accomplished by using metal film of a few tens of nanometers, which greatly facilitates heat transfer from the metal film to the surrounding polymers. Moreover, integrating the metal film composite with a photonic cavity can compensate light absorption loss of the thinner metal film. Theoretical and experimental analysis is conducted for understanding the mechanism behind such improvement. This strategy could be implemented for spatial PA signal patterns, especially for deep tissue PA imaging of implants or image-guiding tools. Furthermore, this approach also provides a guideline for designing photoacoustic transmitters and contrast agents.

  7. Photocatalytic degradation of methyl orange over ITO/Cds/ZnO interface composite films.

    Science.gov (United States)

    Wei, Shouqiang; Shao, Zhongcai; Lu, Xudong; Liu, Ying; Cao, Linlin; He, Yan

    2009-01-01

    ITO/CdS/ZnO interface composite films were successfully prepared by subsequent electrodeposition of CdS and ZnO onto indium tin oxide (ITO) glass substrates. The obtained ITO/CdS/ZnO composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The photocatalytic activity of ITO/CdS/ZnO composite films were investigated using methyl orange (MO) as a model organic compound under UV light irradiation. The influence of operating parameters on MO degradation including initial concentration of MO, pH value of solution, and inorganic anion species over the composite films were examined. A blue shift of absorption threshold was observed for the ITO/CdS/ZnO film in comparison with ITO/ZnO film. ITO/CdS/ZnO composite films prepared under specific conditions showed a higher photocatalytic activity than that of ITO/ZnO films. It was also found that the photocatalytic degradation of MO on the composite films followed pseudo-first order kinetics.

  8. Growth of Ni and Ni-Cr alloy thin films on MgO(001): Effect of alloy composition on surface morphology

    Science.gov (United States)

    Ramalingam, Gopalakrishnan; Reinke, Petra

    2016-12-01

    The effects of substrate treatment, growth temperature, and composition on the surface morphology of Ni-Cr thin films grown on MgO(001) are studied by scanning tunneling microscopy and atomic force microscopy. We demonstrate that a combination of acid-etched substrates and high temperature deposition (400 °C) will result in smooth films with well-defined terraces (up to 30 nm wide) that are suitable for the study of progression of chemical reactions on the surface. Two different treatments are used to prepare the MgO substrates for deposition and they introduce characteristic differences in film surface morphology. Thin films that are grown on the phosphoric acid-treated substrates present reduced nucleation density during the initial stages of film growth which results in long and wide terraces. Due to the ≈16% lattice mismatch in the Ni(001)/MgO(001) system, film growth at 400 °C yields discontinuous films and a two-step growth process is necessary to obtain a continuous layer. Ni films are deposited at 100 °C and subjected to a post-growth annealing at 300 °C for 2 h to obtain a smoother surface. The addition of just 5 wt. % Cr drastically changes the film growth processes and yields continuous films at 400 °C without de-wetting in contrast to pure Ni films. With increasing Cr content, the films become progressively smoother with wider terraces. Ni5Cr alloy thin films have an rms surface roughness of 3.63 ± 0.75 nm, while Ni33Cr thin film is smoother with an rms roughness of only 0.29 ± 0.13 nm. The changes in film growth initiated by alloying with Cr are due to changes in the interfacial chemistry which favorably alters the initial adsorption of the metal atoms on MgO surface and suggests a reduction of the Ehrlich-Schwoebel barrier. The growth of smooth Ni-Cr thin films with a well-defined surface structure opens up a new pathway for a wide range of surface science studies related to alloy performance.

  9. Highly efficient hydrogen evolution reaction using crystalline layered three-dimensional molybdenum disulfides grown on graphene film.

    Energy Technology Data Exchange (ETDEWEB)

    Behranginia, Amirhossein; Asadi, Mohammad; Liu, Cong; Yasaei, Poya; Kumar, Bijandra; Phillips, Patrick; Foroozan, Tara; Waranius, Joseph C.; Kim, Kibum; Abiade, Jeremiah; Klie, Robert F.; Curtiss, Larry A.; Salehi-Khojin, Amin

    2016-01-26

    Electrochemistry is central to applications in the field of energy storage and generation. However, it has advanced far more slowly over the last two decades, mainly because of a lack of suitable and affordable catalysts. Here, we report the synthesis of highly crystalline layered three-dimensional (3D) molybdenum disulfide (MoS2) catalysts with bare Mo-edge atoms and demonstrate their remarkable performance for the hydrogen evolution reaction (HER). We found that Mo-edge-terminated 3D MoS2 directly grown on graphene film exhibits a remarkable exchange current density (18.2 mu A cm(-2)) and turnover frequency (>4 S-1) for HER. The obtained exchange current density is 15.2 and 2.3 times higher than that of MoS2/graphene and MoS2/Au catalysts, respectively, both with sulfided Mo-edge atoms. An easily scalable and robust growth process on a wide variety of substrates, along with prolonged stability, suggests that this material is a promising catalyst in energy-related applications.

  10. Study of the optical properties and structure of ZnSe/ZnO thin films grown by MOCVD with varying thicknesses

    Energy Technology Data Exchange (ETDEWEB)

    Jabri, S., E-mail: slaheddine.jabri@fst.rnu.tn [Unité des nanomatériaux et photoniques, Faculté des Sciences de Tunis, Campus Universitaire Ferhat Hachad, El Manar, 2092 Tunis (Tunisia); Amiri, G.; Sallet, V. [Groupe d’Etude de la Matière Condensée, CNRS-Université de Versailles St Quentin, Université Paris-Saclay, 45 avenue des Etats Unis, 78035 Versailles Cedex (France); Souissi, A. [Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l’Energie, Technopole Borj Cedria, B.P. 95, Hammammlif 2050 (Tunisia); Meftah, A. [Unité des nanomatériaux et photoniques, Faculté des Sciences de Tunis, Campus Universitaire Ferhat Hachad, El Manar, 2092 Tunis (Tunisia); Galtier, P. [Groupe d’Etude de la Matière Condensée, CNRS-Université de Versailles St Quentin, Université Paris-Saclay, 45 avenue des Etats Unis, 78035 Versailles Cedex (France); Oueslati, M. [Unité des nanomatériaux et photoniques, Faculté des Sciences de Tunis, Campus Universitaire Ferhat Hachad, El Manar, 2092 Tunis (Tunisia)

    2016-05-15

    ZnSe layers were grown on ZnO substrates by the metal organic chemical vapor deposition technique. A new structure appeared at lower thicknesses films. The structural properties of the thin films were studied by the X-ray diffraction (XRD) and Raman spectroscopy methods. First, Raman selection rules are explicitly put forward from a theoretical viewpoint. Second, experimentally-retrieved-intensities of the Raman signal as a function of polarization angle of incident light are fitted to the obtained theoretical dependencies in order to confirm the crystallographic planes of zinc blend ZnSe thin film, and correlate with DRX measurements. Raman spectroscopy has been used to characterize the interfacial disorder that affects energy transport phenomena at ZnSe/ZnO interfaces and the Photoluminescence (PL) near the band edge of ZnSe thin films.

  11. Electrical characteristics of 25 nm Pr(ZrTi)O{sub 3} thin films grown on Si by metalorganic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C. H. [Materials Research Laboratory, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Friddle, P. A. [Materials Research Laboratory, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Lu, X. [Materials Research Laboratory, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Chen, Haydn [Materials Research Laboratory, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Kim, Young [Material Research Laboratory, Center for Microanalysis of Materials, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Wu, T. B. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, Republic of China (China)

    2000-08-15

    Pb(Zr{sub 0.5}Ti{sub 0.5})O{sub 3} thin films 25 nm in thickness were grown on LaNiO{sub 3}/Pt/Ti buffered Si substrates at 600 degree sign C by metalorganic chemical vapor deposition. P-E studies showed a remanent polarization value of 8 {mu}C/cm{sup 2} with a coercive field of 200 kV/cm. In polarization fatigue studies, these films only showed slight degradation in remanent polarization up to 4x10{sup 8} cycles ({+-}3 V oscillation) before breakdown. Moreover, the effect of space charge on the C-V behavior of these films was illustrated I-V characteristics of these films were also described. (c) 2000 American Institute of Physics.

  12. Phytochemical Composition and Antioxidant Capacity of Seven Saskatoon Berry (Amelanchier alnifolia Nutt. Genotypes Grown in Poland

    Directory of Open Access Journals (Sweden)

    Sabina Lachowicz

    2017-05-01

    Full Text Available The basic chemical composition, bioactive compounds, and antioxidant capacity of fruits of three new Polish breeding clones (No. 5/6, type S, and type N and four Canadian cultivars (cvs. (“Martin”, “Smoky”, “Pembina”, and “Honeywood” grown in Poland in 2016 were investigated. Fruits were analyzed for their contents of triterpenoids, carotenoids, chlorophylls, and polyphenolics with the ultra-performance liquid chromatography photodiode detector-quadrupole/time-of-flight mass spectrometry (UPLC-PDA-Q/TOF-MS method, sugar with the high-performance liquid chromatography–evaporative light scattering detector (HPLC-ELSD method, and antioxidant capacity with the ability to reduce free radical (ABTS and ferric reducing ability of plasma (FRAP method. Thirty-eight bioactive compounds, including twenty-eight polyphenolic compounds (four anthocyanins, nine phenolic acids, nine flavonols, and seven flavan-3-ols, four carotenoids, two chlorophylls, and three triterpenoids were identified in the fruits. The fruits of the tested Saskatoon berry genotypes were found to be rich in phenolic compounds (3773.94–6390.36 mg/100 g·dm, triterpenoids (66.55–91.31 mg/kg·dm, and carotenoids (478.62–561.57 mg/kg·dm, with high ABTS and FRAP capacity (10.38–34.49 and 9.66–25.34 mmol·Trolox/100 g·dm, respectively. Additionally, the berries of these genotypes seemed to be a good source of sugar (9.02–19.69 g/100 g, pectins (0.67%–1.33%, and ash (0.59%–0.67%. Some genotypes of Saskatoon berry, especially the clones type S, type N, and cvs. “Honeywood” and “Smoky”, may be selected for their potential applications in commercial cultivation to produce fruits with valuable health-promoting nutritional effects on human health. Additionally, three new genotypes that may offer new functional materials can be recommended for fruit growers.

  13. Enhancement of polar crystalline phase formation in transparent PVDF-CaF{sub 2} composite films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Goo; Ha, Jong-Wook, E-mail: jongwook@krict.re.kr; Sohn, Eun-Ho; Park, In Jun; Lee, Soo-Bok

    2016-12-30

    Highlights: • The crystalline phase in transparent PVDF-CaF{sub 2} composite films was investigated. • CaF{sub 2} promoted the formation of polar crystalline phases in PVDF matrix. • Ordered γ-phase was obtained by thermal treatment of as-cast films at the vicinity of its melting temperature. - Abstract: We consider the influence of calcium fluoride (CaF{sub 2}) nanoparticles on the crystalline phase formation of poly(vinylidene fluoride) (PVDF) for the first time. The transparent PVDF-CaF{sub 2} composite films were prepared by casting on PET substrates using N,N-dimethylacetamide (DMAc) as a solvent. It was found that CaF{sub 2} promoted the formation of polar crystalline phase of PVDF in composites, whereas nonpolar α-phase was dominant in the neat PVDF film prepared at the same condition. The portion of polar crystalline phase increased in proportional to the weight fraction of CaF{sub 2} in the composite films up to 10 wt%. Further addition of CaF{sub 2} suppressed completely the α-phase formation. Polar crystalline phase observed in as-cast composite films was a mixture of β- and γ-polymorph structures. It was also shown that much ordered γ-phase could be obtained through thermal treatment of as-cast PVDF-CaF{sub 2} composite film at the temperatures above the melting temperature of the composite films, but below that of γ-phase.

  14. Carrier transport and photoluminescence properties of Ga-doped ZnO films grown by ion-plating and by atmospheric-pressure CVD

    Energy Technology Data Exchange (ETDEWEB)

    Terasako, T., E-mail: terasako.tomoaki.mz@ehime-u.ac.jp [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama-shi, Ehime 790-8577 (Japan); Ogura, Y.; Fujimoto, S. [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama-shi, Ehime 790-8577 (Japan); Song, H.; Makino, H. [Materials Design Center, Research Institute, Kochi University of Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-shi, Kochi 782-8502 (Japan); Yagi, M. [Kagawa National College of Technology, 551 Koda, Takuma-cho, Mitoyo-shi, Kagawa 769-1192 (Japan); Shirakata, S. [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama-shi, Ehime 790-8577 (Japan); Yamamoto, T. [Materials Design Center, Research Institute, Kochi University of Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-shi, Kochi 782-8502 (Japan)

    2013-12-31

    Ga-doped ZnO (GZO) films with carrier concentrations ranging from 5.2 × 10{sup 17} to 2.9 × 10{sup 20} cm{sup −3} were grown on r-plane sapphire substrates by atmospheric-pressure CVD (AP-CVD). The gradients of Hall mobility (μ) — temperature (T) curves (denoted by Δμ/ΔT) for the GZO films grown by AP-CVD (CVD-GZO films) plotted as a function of carrier concentration n obey those for the GZO films deposited by ion plating with dc arc discharge (IP-GZO films). This suggests that the dominant carrier scattering mechanism limiting the carrier transport is common between the CVD-GZO and IP-GZO films at any given n. The CVD-GZO films with low n exhibited the Ga-related neutral donor bound exciton and two-electron satellite (TES) lines at low temperature. With increasing n, the above two characteristic lines shifted higher energies accompanied by broadening. The IP-GZO films exhibited two emission lines with opposite n dependences; with increasing n, one line shifted towards higher energies, whereas another line shifted towards lower energies. With an increase in n caused by the donor doping, the relaxation of the momentum-conservation law brought the remarkable changes to the PL and PLE spectra of both the IP-GZO and CVD-GZO films with n of more than 4.0 × 10{sup 19} cm{sup −3} that is close to the Mott density. - Highlights: • Ga-doped ZnO films were prepared by atmospheric-pressure CVD and ion-plating. • The ∆μ/∆T plots for the CVD-GZO films obey those for the IP-GZO films. • Carrier concentration dependences of PL and PLE properties were examined. • PL and PLE spectra of the GZO films changed markedly at n = 4.0 × 10{sup 19} cm{sup −3}.

  15. Deposition and computational analysis of Wc thin films grown by PAPVD

    Energy Technology Data Exchange (ETDEWEB)

    Agudelo M, L. C.; Ospina O, R.; Gonzalez C, J. M., E-mail: lxtina@gmail.com [Universidad Nacional de Colombia, Sede Manizales, Laboratorio de Fisica del Plasma, Km. 7 via a Magdalena, (6) 88779400 Manizales, Caldas (Colombia)

    2013-10-01

    Tungsten carbide (Wc) is considered a very important material used for industrial applications due to their high hardness and wear resistance. In this work the production of Wc coatings using repetitive pulsed arc plasma assisted physical vapor deposition (PAPVD) system is studied. During the deposition process a W target was used as cathode. The atmosphere is a mixture of argon (50%) and methane (50%). As is known, the use of methane as precursor gas for Wc production causes the formation of different phases such as Wc and W{sub 2}C. The power supply allows varying the pulses active and passive times, having a value which of 1 s. Coatings were characterized by X-ray diffraction and X-ray photoelectron spectroscopy for determining their chemical composition, structure and stoichiometry. Density functional theory methods were used for performing studies of the Wc stability. It was carried out using computational techniques by means of charge distribution and molecular orbital, finding a transition from hybridization of d shell to the f shell. (Author)

  16. Domain structure and magnetic properties of epitaxial SrRuO sub 3 films grown on SrTiO sub 3 (100) substrates by ion beam sputtering

    CERN Document Server

    Oh, S H

    2000-01-01

    The domain structure of epitaxial SrRuO sub 3 thin films grown on SrTiO sub 3 (100) substrates by using ion beam sputtering has been investigated with transmission electron microscopy (TEM) and X-ray diffraction (XRD). The SrRuO sub 3 films grown in the present study revealed a unique cube-on-cube epitaxial relationship, i.e., (100) sub S sub R sub O ll (100) sub S sub T sub O , [010] sub S sub R sub O ll [101] sub S sub T sub O , prevailing with a cubic single-domain structure. The cubic SrRuO sub 3 thin films that were inherently with free from RuO sub 6 octahedron tilting exhibited higher resistivity with suppressed magnetic properties. The Curie temperature of the thin films was suppressed by 60 K from 160 K for the bulk specimen, and the saturation magnetic moment was reduced by a significant amount. The tetragonal distortion of the SrRuO sub 3 thin films due to coherent growth with the substrate seemed to result in a strong magnetic anisotropy.

  17. Crystal structure and composition of BAlN thin films: Effect of boron concentration in the gas flow

    KAUST Repository

    Wang, Shuo

    2017-07-20

    We have investigated the microstructure of BxAl1-xN films grown by flow-modulated epitaxy at 1010 oC, with B/(B+Al) gas-flow ratios ranging from 0.06 to 0.18. The boron content obtained from X-ray diffraction (XRD) patterns ranges from x = 0.02 to 0.09. On the other hand, boron content deduced from the aluminum signal in the Rutherford backscattering spectra (RBS) ranges x = 0.06 to 0.16, closely following gas-flow ratios. Transmission electron microscopy indicates the sole presence of wurtzite crystal structure in the BAlN films, and a tendency towards columnar growth for B/(B+Al) gas-flow ratios below 0.12. For higher ratios, the BAlN films exhibit a tendency towards twin formation and finer microstructure. Electron energy loss spectroscopy has been used to profile spatial variations in the composition of the films.The RBS data suggest that the incorporation of B is highly efficient for our growth method, while the XRD data indicate that the epitaxial growth may be limited by a solubility limit in the crystal phase at about 9%, for the range of B/(B+Al) gas-flow ratios that we used, which is significantly higher than previously thought.

  18. Crystal structure and composition of BAlN thin films: Effect of boron concentration in the gas flow

    Science.gov (United States)

    Wang, Shuo; Li, Xiaohang; Fischer, Alec M.; Detchprohm, Theeradetch; Dupuis, Russell D.; Ponce, Fernando A.

    2017-10-01

    We have investigated the microstructure of BxAl1-xN films grown by flow-modulated epitaxy at 1010 °C, with B/(B + Al) gas-flow ratios ranging from 0.06 to 0.18. The boron content obtained from X-ray diffraction (XRD) patterns ranges from x = 0.02 to 0.09. On the other hand, boron content deduced from the aluminum signal in the Rutherford backscattering spectra (RBS) ranges from x = 0.06 to 0.16, closely following the gas-flow ratios. Transmission electron microscopy indicates the sole presence of a wurtzite crystal structure in the BAlN films, and a tendency towards columnar growth for B/(B + Al) gas-flow ratios below 0.12. For higher ratios, the BAlN films exhibit a tendency towards twin formation and finer microstructure. Electron energy loss spectroscopy has been used to profile spatial variations in the composition of the films. The RBS data suggest that the incorporation of B is highly efficient for our growth method, while the XRD data indicate that the epitaxial growth may be limited by a solubility limit in the crystal phase at about 9%, for the range of B/(B + Al) gas-flow ratios that we have studied, which is significantly higher than previously thought.

  19. Electrical and optical properties of indium zinc oxide (IZO) thin films by continuous composition spread.

    Science.gov (United States)

    Lee, J J; Kim, J S; Yoon, S J; Cho, Y S; Choi, J W

    2013-05-01

    Indium zinc oxide (IZO) films were deposited on glass substrate at room temperature using off-axis RF sputtering-continuous composition spread (CCS) system. The full range composition of IZO films were controlled by the deposition rate and thickness profiles of In2O3 and ZnO target. The structural, electrical and optical properties of IZO thin films were measured as functions of position. IZO thin film had the lowest resistivity and highest carrier concentration at the position of 15 mm (5.02 x 10(-4) omega cm, 3.9 x 10(20)/cm3). And IZO thin film had high transmittance in visible region at measured all positions. This study has investigated to explore the new composition of IZO films using CCS system.

  20. Electrophoretic deposition of composite halloysite nanotube–hydroxyapatite–hyaluronic acid films

    Energy Technology Data Exchange (ETDEWEB)

    Deen, I. [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Zhitomirsky, I., E-mail: zhitom@mcmaster.ca [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada)

    2014-02-15

    Highlights: ► Composite halloysite nanotubes–hydroxyapatite–hyaluronic acid films were prepared. ► Electrophoretic deposition method was used for deposition. ► Natural hyaluronic acid was used as a dispersing, charging and film forming agent. ► Film composition and deposition yield can be varied. ► The films can be used for biomedical implants with controlled release of drugs. -- Abstract: Electrophoretic deposition method has been developed for the deposition of biocomposite films containing halloysite nanotubes (HNTs), hydroxyapatite (HA) and hyaluronic acid. The method is based on the use of natural hyaluronate biopolymer as a dispersing and charging agent for HNT and HA and film forming agent for the fabrication of the composite films. The deposition kinetics was studied by the quartz crystal microbalance method. The composite films were studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis and electron microscopy. The composite films are promising materials for the fabrication of biomedical implants with advanced functional properties.

  1. Surface composition of magnetron sputtered Pt-Co thin film catalyst for proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Vorokhta, Mykhailo, E-mail: vorohtam@gmail.com [Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague (Czech Republic); Khalakhan, Ivan; Václavů, Michal [Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague (Czech Republic); Kovács, Gábor; Kozlov, Sergey M. [Departament de Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1, 08028 Barcelona (Spain); Kúš, Peter; Skála, Tomáš; Tsud, Natalia; Lavková, Jaroslava [Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague (Czech Republic); Potin, Valerie [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université Bourgogne, 9 Av. A. Savary, BP 47870, F-21078 Dijon Cedex (France); and others

    2016-03-01

    Graphical abstract: - Highlights: • Nanostructured Pt-Co thin catalyst films were grown on carbon by magnetron sputtering. • The surface composition of the nanostructured Pt-Co films was investigated by surface analysis techniques. • We carried out modeling of Pt-Co nanoalloys by computational methods. • Both experiment and modeling based on density functional theory showed that the surface of Pt-Co nanoparticles is almost exclusively composed of Pt atoms. - Abstract: Recently we have tested a magnetron sputtered Pt-Co catalyst in a hydrogen-fed proton exchange membrane fuel cell and showed its high catalytic activity for the oxygen reduction reaction. Here we present further investigation of the magnetron sputtered Pt-Co thin film catalyst by both experimental and theoretical methods. Scanning electron microscopy and transmission electron microscopy experiments confirmed the nanostructured character of the catalyst. The surface composition of as-deposited and annealed at 773 K Pt-Co films was investigated by surface analysis techniques, such as synchrotron radiation photoelectron spectroscopy and X-ray photoelectron spectroscopy. Modeling based on density functional theory showed that the surface of 6 nm large 1:1 Pt-Co nanoparticles is almost exclusively composed of Pt atoms (>90%) at typical operation conditions and the Co content does not exceed 20% at 773 K, in agreement with the experimental characterization of such films annealed in vacuum. According to experiment, the density of valence states of surface atoms in Pt-Co nanostructures is shifted by 0.3 eV to higher energies, which can be associated with their higher activity in the oxygen reduction reaction. The changes in electronic structure caused by alloying are also reflected in the measured Pt 4f, Co 3p and Co 2p photoelectron peak binding energies.

  2. Role of the substrate on the magnetic anisotropy of magnetite thin films grown by ion-assisted deposition

    Science.gov (United States)

    Prieto, Pilar; Prieto, José Emilio; Gargallo-Caballero, Raquel; Marco, José Francisco; de la Figuera, Juan

    2015-12-01

    Magnetite (Fe3O4) thin films were deposited on MgO (0 0 1), SrTiO3 (0 0 1), LaAlO3 (0 0 1) single crystal substrates as well on as silicon and amorphous glass in order to study the effect of the substrate on their magnetic properties, mainly the magnetic anisotropy. We have performed a structural, morphological and compositional characterization by X-ray diffraction, atomic force microscopy and Rutherford backscattering ion channeling in oxygen resonance mode. The magnetic anisotropy has been investigated by vectorial magneto-optical Kerr effect. The results indicate that the magnetic anisotropy is especially influenced by the substrate-induced microstructure. In-plane isotropy and uniaxial anisotropy behavior have been observed on silicon and glass substrates, respectively. The transition between both behaviors depends on grain size. For LaAlO3 substrates, in which the lattice mismatch between the Fe3O4 films and the substrate is significant, a weak in-plane fourfold magnetic anisotropy is induced. However when magnetite is deposited on MgO (0 0 1) and SrTiO3 (0 0 1) substrates, a well-defined fourfold in-plane magnetic anisotropy is observed with easy axes along [1 0 0] and [0 1 0] directions. The magnetic properties on these two latter substrates are similar in terms of magnetic anisotropy and coercive fields.

  3. Effect of processing method on the proximate composition, mineral content and antinutritional factors to taro (Colocasia esculenta, L.) grown in Ethiopia

    National Research Council Canada - National Science Library

    Adane, T; Tilahun, B; Haki, Gulelat Desse; Shimelis, A; Negussie, R

    2013-01-01

    Although taro is widely grown in Ethiopia, it is an underutilized crop and little is known about its proximate and micro-element composition and the antinutritional factors of the raw, boiled and fermented products...

  4. Continuous Preparation of Copper/Carbon Nanotube Composite Films and Application in Solar Cells.

    Science.gov (United States)

    Luo, Xiao Gang; Le Wu, Min; Wang, Xiao Xia; Zhong, Xin Hua; Zhao, Ke; Wang, Jian Nong

    2016-02-08

    Realizing the continuous and large scale preparation of particle/carbon nanotube (CNT) composites with enhanced functionalities, and broad applications in energy conversion, harvesting, and storage systems, remains as a big challenge. Here, we report a scalable strategy to continuously prepare particle/CNT composite films in which particles are confined by CNT films. This is achieved by the continuous condensation and deposition of a cylindrical assembly of CNTs on a paper strip and the in situ incorporation of particles during the layer-by-layer deposition process. A Cu/CNT composite film is prepared as an example; such a film exhibits very high power conversion efficiency when it is used as a counter electrode in a solar cell, compared with previous materials under otherwise identical conditions. The proposed method can be extended to other CNT-based composite films with excellent functionalities for wide applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    (001)-oriented BiFeO 3 (BFO) thin films were grown on Sr xCa 1-xRuO 3- (SCRO; x = 1, 0.67, 0.33, 0) buffered SrTiO 3 (001) substrates using pulsed laser deposition. The microstructural, electrical, ferroelectric, and piezoelectric properties of the thin films were considerably affected by the buffer layers. The interface between the BFO films and the SCRO-buffer layer was found to play a dominant role in determining the electrical and piezoelectric behaviors of the films. We found that films grown on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  6. The effect of sputtering gas pressure on the structure and optical properties of MgNiO films grown by radio frequency magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Wuze; Jiao, Shujie, E-mail: shujiejiao@gmail.com; Wang, Dongbo; Gao, Shiyong; Wang, Jinzhong; Yu, Qingjiang; Li, Hongtao

    2017-05-31

    Highlights: • MgNiO thin films were fabricated by radio frequency magnetron sputtering. • The structure and optical properties of MgNiO films were studied. • The mechanism of phase separation was discussed in detail. • The effect of different sputtering pressure also was discussed. - Abstract: In this study, MgNiO thin films were grown on quartz substrates by radio frequency (RF) magnetron sputtering. The influence of different sputtering pressures on the crystalline and optical properties of MgNiO thin films has been studied. X-ray diffraction measurement indicates that the MgNiO films are cubic structure with (200) preferred orientation. UV–vis transmission spectra show that all the MgNiO thin films show more than 75% transmission at visible region, and the absorption edges of all thin films locate at solar-blind region (220 nm–280 nm). The lattice constant and Mg content of MgNiO samples were calculated using X-ray diffraction and transmission spectra data. The phase separation is observed both in the X-ray diffraction patterns and transmission spectra, and the phase separation is studied in detail based on the crystal growth theory and sputtering process.

  7. Large critical current densities and pinning forces in CSD-grown superconducting GdBa2Cu3O7-x -BaHfO3 nanocomposite films

    Science.gov (United States)

    Cayado, Pablo; Erbe, Manuela; Kauffmann-Weiss, Sandra; Bühler, Carl; Jung, Alexandra; Hänisch, Jens; Holzapfel, Bernhard

    2017-09-01

    GdBa2Cu3O7-x -BaHfO3 (GdBCO-BHO) nanocomposite (NC) films containing 12 mol% BHO nanoparticles were prepared by chemical solution deposition (CSD) following the TFA route on SrTiO3 (STO) single crystals and buffered metallic tapes supplied by two different companies: Deutsche Nanoschicht GmbH and SuperOx. We optimized the preparation of our GdBCO-BHO solutions with acetylacetone making the film synthesis very robust and reproducible, and obtained 220 nm films with excellent superconducting properties. We show the structural, morphological and superconducting properties of the films after a careful optimization of the processing parameters (growth temperature, oxygen partial pressure and heating ramp). The films reach critical temperatures (T c) of ˜94 K, self-field critical current densities (J c) of >7 MA cm- 2 and maximum pinning force densities (F p) of ˜16 GN m- 3 at 77 K on STO and T c of ˜94.5 K and J c > 1.5 MA cm- 2 on buffered metallic tapes. The transport properties under applied magnetic fields are significantly improved with respect to the pristine GdBCO films. The GdBCO-BHO NC films on STO present epitaxial c-axis orientation with excellent out-of-plane and in-plane texture. The films are, in general, very dense with a low amount of pores and only superficial indentations. On the other hand, we present, for the first time, a systematic study of CSD-grown GdBCO-BHO NC films on buffered metallic tapes. We have used the optimized growth conditions for STO as a reference and identified some limitations on the film synthesis that should be overcome for further improvement of the films’ superconducting properties.

  8. Electroplating of CdTe Thin Films from Cadmium Sulphate Precursor and Comparison of Layers Grown by 3-Electrode and 2-Electrode Systems

    Directory of Open Access Journals (Sweden)

    Imyhamy M. Dharmadasa

    2017-01-01

    Full Text Available Electrodeposition of CdTe thin films was carried out from the late 1970s using the cadmium sulphate precursor. The solar energy group at Sheffield Hallam University has carried out a comprehensive study of CdTe thin films electroplated using cadmium sulfate, cadmium nitrate and cadmium chloride precursors, in order to select the best electrolyte. Some of these results have been published elsewhere, and this manuscript presents the summary of the results obtained on CdTe layers grown from cadmium sulphate precursor. In addition, this research program has been exploring the ways of eliminating the reference electrode, since this is a possible source of detrimental impurities, such as K+ and Ag+ for CdS/CdTe solar cells. This paper compares the results obtained from CdTe layers grown by three-electrode (3E and two-electrode (2E systems for their material properties and performance in CdS/CdTe devices. Thin films were characterized using a wide range of analytical techniques for their structural, morphological, optical and electrical properties. These layers have also been used in device structures; glass/FTO/CdS/CdTe/Au and CdTe from both methods have produced solar cells to date with efficiencies in the region of 5%–13%. Comprehensive work carried out to date produced comparable and superior devices fabricated from materials grown using 2E system.

  9. Data storage applications based on LiCoO{sub 2} thin films grown on Al{sub 2}O{sub 3} and Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Svoukis, E., E-mail: svoukis.efthymios@ucy.ac.cy [Nanotechnology Research Unit & Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Av., 1678 Nicosia (Cyprus); Mihailescu, C.N. [Nanotechnology Research Unit & Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Av., 1678 Nicosia (Cyprus); National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, P.O. Box MG-36, 077125 Magurele (Romania); Mai, V.H. [CEA, LIST, 91191 Gif sur Yvette Cedex (France); Schneegans, O. [Laboratoire Génie Electrique et Electronique de Paris, UMR 8507 of CNRS, UPMC and Paris-Sud Universities, Supélec, 91192 Gif sur Yvette Cedex (France); Breza, K.; Lioutas, C. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Giapintzakis, J., E-mail: giapintz@ucy.ac.cy [Nanotechnology Research Unit & Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Av., 1678 Nicosia (Cyprus)

    2016-09-15

    Highlights: • LiCoO{sub 2} thin films are shown to be potential candidates for data storage applications. • High quality LiCoO{sub 2} thin films have been grown by PLD on (0 0 0 1) Al{sub 2}O{sub 3} and (111) Si substrates. • Epitaxial relations have been determined for LiCoO{sub 2}/Al{sub 2}O{sub 3} with high resolution X-ray diffraction (in-plane and out-of-plane configurations). • Surface resistance modification have been obtained by the application of an external bias voltage. • A mechanism for the surface resistance modifications is presented. - Abstract: In this study, LiCoO{sub 2} thin films were investigated for data storage applications based on scanning probe mediated approaches. LiCoO{sub 2}, compared to other materials proposed for scanning probe mediated nanoscale patterning, is highly stable and exhibits reversible electrochemical surface modifications. LiCoO{sub 2} thin films have been grown by pulsed laser deposition on Al{sub 2}O{sub 3} and Si substrates over a range of deposition temperatures. The crystal structure and the microstructure of the films has been inferred through in- and out-of-plane X-ray diffraction studies and high-resolution transmission electron microscopy, respectively. The influence of the film deposition temperature on the surface electrical properties of the LiCoO{sub 2} films is discussed along with the relevant mechanism of surface resistance modification.

  10. Role of dislocations and carrier concentration in limiting the electron mobility of InN films grown by plasma assisted molecular beam epitaxy

    Science.gov (United States)

    Tangi, Malleswararao; De, Arpan; Shivaprasad, S. M.

    2018-01-01

    We report the molecular beam epitaxy growth of device quality InN films on GaN epilayer and nano-wall network (NWN) templates deposited on c-sapphire by varying the film thickness up to 1 μm. The careful experiments are directed towards obtaining high mobility InN layers having a low band gap with improved crystal quality. The dislocation density is quantified by using high resolution X-ray diffraction rocking curve broadening values of symmetric and asymmetric reflections, respectively. We observe that the dislocation density of the InN films grown on GaN NWN is less than that of the films grown on the GaN epilayer. This is attributed to the nanoepitaxial lateral overlayer growth (ELOG) process, where the presence of voids at the interface of InN/GaN NWN prevents the propagation of dislocation lines into the InN epilayers, thereby causing less defects in the overgrown InN films. Thus, this new adaptation of the nano-ELOG growth process enables us to prepare InN layers with high electron mobility. The obtained electron mobility of 2121 cm2/Vs for 1 μm thick InN/GaN NWN is comparable with the literature values of similar thickness InN films. Furthermore, in order to understand the reasons that limit electron mobility, the charge neutrality condition is employed to study the variation of electron mobility as a function of dislocation density and carrier concentration. Overall, this study provides a route to attaining improved crystal quality and electronic properties of InN films.

  11. The photosensitivity of carbon quantum dots/CuAlO2 films composites.

    Science.gov (United States)

    Pan, Jiaqi; Sheng, Yingzhuo; Zhang, Jingxiang; Wei, Jumeng; Huang, Peng; Zhang, Xin; Feng, Boxue

    2015-07-31

    Carbon quantum dots/CuAlO2 films were prepared by a simple route through which CuAlO2 films prepared by sol-gel on crystal quartz substrates were composited with carbon quantum dots on their surface. The characterization results indicated that CuAlO2 films were well combined with carbon quantum dots. The photoconductivity of carbon quantum dots/CuAlO2 films was investigated under illumination and darkness switching, and was demonstrated to be significantly enhanced compared with CuAlO2 films. Through analysis, this enhancement of photoconductivity was attributed to the carbon quantum dots with unique up-converted photoluminescence behavior.

  12. Crambe tataria sebeók seeds and plants grown in vitro and in vivo fatty acid composition comparison

    Directory of Open Access Journals (Sweden)

    Nadia Oleksandrivna Pushkarova

    2016-10-01

    Full Text Available Methods of in vitro conservation offer a number of advantages for endangered species preservation. Crambe tataria Sebeók biochemistry study (fatty acid (FA composition, antioxidant activity (AOA, polyfructan and total soluble protein content is fairly importaint and could show the potential value of this species in agriculture, Food and Chemical Industry or pharmacology including its use as a source of valuble genetic material and could lead to new promising sources of biofuel discovery. Also, comparison of in vitro and in vivo cultured plants could point out to the effect of in vitro culture methods on plants biochemical composition Fatty acid (FA content was determined using Gas chromatography-mass spectrophotometry (GC/MS of fatty acid ethers. Antioxidant activity was determined using DPPH (2,2-diphenyl-1-picrylhydrazyl radical scavenging method. Total soluble protein content was measured using Bradford method and polyfructan content determination was based upon ketosugars ability to color in the acidic environment with resorcinol. Plants that were grown under in vitro and in vivo conditions and seeds were used in this research. Obtained data showed that C. tataria plants had high AOA and total soluble protein content along with high total FA content along with high content of α-Linolenic acid and absence of erucic acid. Difference in biochemical composition between plants grown in aseptic and not aseptic conditions was shown. 

  13. Compositional and structural properties of pulsed laser-deposited ZnS:Cr films

    Science.gov (United States)

    Nematollahi, Mohammadreza; Yang, Xiaodong; Seim, Eivind; Vullum, Per Erik; Holmestad, Randi; Gibson, Ursula J.; Reenaas, Turid W.

    2016-02-01

    We present the properties of Cr-doped zinc sulfide (ZnS:Cr) films deposited on Si(100) by pulsed laser deposition. The films are studied for solar cell applications, and to obtain a high absorption, a high Cr content (2.0-5.0 at.%) is used. It is determined by energy-dispersive X-ray spectroscopy that Cr is relatively uniformly distributed, and that local Cr increases correspond to Zn decreases. The results indicate that most Cr atoms substitute Zn sites. Consistently, electron energy loss and X-ray photoelectron spectroscopy showed that the films contain mainly Cr2+ ions. Structural analysis showed that the films are polycrystalline and textured. The films with ~4 % Cr are mainly grown along the hexagonal [001] direction in wurtzite phase. The average lateral grain size decreases with increasing Cr content, and at a given Cr content, increases with increasing growth temperature.

  14. Composition-ratio control of CuInS{sub 2} films using PLD

    Energy Technology Data Exchange (ETDEWEB)

    Wakita, Kazuki; Po-Han, Tseng; Yoshida, Ryo; Kyan, Issei [Department of Electrical and Electronic Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016 (Japan); Shim, Yong-Gu [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, Naka-ku, Sakai, Osaka 599-8531 (Japan)

    2017-06-15

    A sulfur-annealing treatment was investigated to control the sulfur content of epitaxial CuInS{sub 2} films grown on GaAs substrate by PLD. The sulfur-annealing treatment improved the surface roughness and film crystallinity. Photoluminescence measurements obtained using the confocal microspectroscopy demonstrated that the annealed films show band-edge emissions over a very large area. Electron-probe microanalysis measurements indicated that the sulfur content of the annealed films was about 50 at.%, and the content of the emission area was more than 50 at.%. Therefore, the sulfur content of epitaxial CuInS{sub 2} films was successfully controlled by the sulfur-annealing treatment. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Preparation of Composite Films of a Conjugated Polymer and C60NWs and Their Photovoltaic Application

    OpenAIRE

    Takatsugu Wakahara; Kun’ichi Miyazawa; Osamu Ito; Nobutaka Tanigaki

    2016-01-01

    Composite films of conjugated polymers, such as poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly(3-hexylthiophene) (P3HT), with C60 nanowhiskers (C60NWs) were prepared. The photoluminescence originating from the conjugated MDMO-PPV polymers was effectively quenched in the composite film, indicating a strong interaction between the conjugated polymer and C60NWs. The photovoltaic devices were fabricated using C60NW (conjugated polymer) composite films, result...

  16. Potentiality of the composite fulleren based carbon films as the stripper foils for tandem accelerators

    CERN Document Server

    Vasin, A V; Rusavsky, A V; Totsky, Y I; Vishnevski, I N

    2001-01-01

    The problem of the radiation resistance of the carbon stripper foils is considered. The short review of the experimental data available in literature and original experimental results of the are presented. In the paper discussed is the possibility of composite fulleren based carbon films to be used for preparation of the stripper foils. Some technological methods for preparation of composite fulleren based carbon films are proposed. Raman scattering and atom force microscopy were used for investigation of the fulleren and composite films deposited by evaporation of the C sub 6 sub 0 fulleren powder.

  17. Study of the optical absorption and photoluminescence in (Pb,Gd)3(Al,Ga)5O12: Ce epitaxial films grown from Pb-containing melt solutions

    Science.gov (United States)

    Vasil’ev, D. A.; Spassky, D. A.; Omelkov, S. I.; Vasil’eva, N. V.; Khakhalin, A. V.; Plotnichenko, V. G.

    2017-11-01

    The optical absorption and photoluminescence properties of cerium-activated (Pb,Gd)3(Al,Ga)5O12 epitaxial films are studied. The films are grown on single-crystal (111)-oriented Gd3Ga5O12 substrates by liquid-phase epitaxy from supercooled PbO – B2O3 melt solutions at different concentrations of gadolinium, cerium, and aluminium oxides in the charge. The photoluminescence band of Ce3+ ions is shown to peak at 532 nm. The highest cathodoluminescence yield of about 51500 photons MeV‑1 at a decay time of the slow component of 61.0 ns (light yield fraction 68%) is found for the Pb0.01Ce0.03Gd2.96Al3.14Ga1.86O12 film, grown from melt solution with gadolinium oxide, cerium oxide, and aluminium oxide concentrations of 0.4, 0.2, and 4.5 mol % in the charge, respectively. Epitaxial films with these spectroscopic characteristics are promising for application in scintillation screens.

  18. Schottky barrier contacts formed on polar and nonpolar Mg{sub x}Zn{sub 1-x}O films grown by remote plasma enhanced MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, A.; Hayashi, T.; Temmyo, J. [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8011 (Japan); Hierro, A.; Tabares, G.; Ulloa, J.M.; Munoz, E. [Dpto. Ingenieria Electronica and ISOM, Universidad Politechnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

    2010-06-15

    The growth of Mg{sub x}Zn{sub 1-x}O films of both polar and nonpolar orientation in was successfully carried out by remote-plasma-enhanced MOCVD (RPE-MOCVD) technique. The polar face of as-grown film had a vertically aligned columnar growth with respect to the sapphire (11-20) substrate. These columns had an average diameter of about 40 nm. In contrast, the nonpolar face of as-grown film had a sword-shape lying with an average width of 250 nm on the sapphire (10-12) substrate. Au/Schottky diodes (SDs) were fabricated on both polar face of c-plane (0001) Mg{sub x}Zn{sub 1-x}O and nonpolar face of a-plane (11-20) Mg{sub x}Zn{sub 1-x}O. A rectifying behavior had been achieved and a series resistance was increased with Mg contents in both polar and nonpolar diodes. A residual electron concentration was decreased with the Mg content from 3 x 10{sup 17} cm{sup -3} at x = 0 to 1.2 x 10{sup 16} cm{sup -3} at x = 0.18 in the case of nonpolar films. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  19. Composite Materials and Films Based on Melanins, Polydopamine, and Other Catecholamine-Based Materials

    Directory of Open Access Journals (Sweden)

    Vincent Ball

    2017-07-01

    Full Text Available Polydopamine (PDA is related to eumelanins in its composition and structure. These pigments allow the design, inspired by natural materials, of composite nanoparticles and films for applications in the field of energy conversion and the design of biomaterials. This short review summarizes the main advances in the design of PDA-based composites with inorganic and organic materials.

  20. Influence of film thickness and annealing temperature on the structural and optical properties of ZnO thin films on Si (1 0 0) substrates grown by atomic layer deposition

    Science.gov (United States)

    Tian, Ji-Li; Zhang, Hua-Yu; Wang, Gui-Gen; Wang, Xin-Zhong; Sun, Rui; Jin, Lei; Han, Jie-Cai

    2015-07-01

    In this paper, ZnO thin films with different thicknesses grown on Si (1 0 0) substrates by atomic layer deposition (ALD) method were annealed in nitrogen at the temperatures ranging from 200 to 900 °C. The influences of film thickness and annealing temperature on the structural and optical properties of the ZnO films were systematically investigated by XRD, SEM and RT-PL. All the ALD-ZnO thin films show polycrystalline hexagonal wurtzite structure and a high preferential c-axis orientation. The results show that the crystallinity quality and luminescence performance are both improved by increasing the film thickness. In addition, the loss of oxygen which results in the formation of oxygen vacancies (VO) is the main reason for the green emission dominating visible band of annealed ZnO thin films. The visible band is dominated by different kinds of defects including oxygen vacancies (VO and VO+), and interstitial oxygen (IO) with increasing annealing temperature. High-quality ZnO thin films with good luminescence performance can be obtained for the films annealed at 800 °C in nitrogen.

  1. Defect-induced excitonic recombination in Ti x Zn1- x O thin films grown by DC-unbalanced magnetron sputtering

    Science.gov (United States)

    Nurfani, Eka; Kurniawan, Robi; Aono, Takashige; Takeda, Kohei; Shirai, Yuma; Sutjahja, Inge M.; Rusydi, Andrivo; Winata, Toto; Takase, Kouichi; Darma, Yudi

    2017-11-01

    We study the effects of Ti doping on the near-band-edge emission (NBE) and defect-related deep-level emission (DLE) of ZnO thin films grown by DC unbalanced magnetron sputtering. DLE in pure ZnO is contributed by zinc and oxygen vacancies (VZn+VO), as revealed by photoluminescence (PL) spectroscopy, current-voltage (I-V) characteristic measurement, and spectroscopic ellipsometry. The reduction in the number of VZn states is clearly observed upon Ti doping, resulting in the enhancement of green emission from VO. Interestingly, the thin film with a Ti concentration of 1 at. % shows a higher excitonic emission. Furthermore, the temperature dependence of PL spectra shows that the enhanced excitonic emission originates from the donor-bound exciton promoted by the Ti dopant and native VO. This study shows an important role of the defects in controlling the optical and electronic properties of ZnO films for future optoelectronic applications.

  2. Domain formation due to surface steps in topological insulator Bi{sub 2}Te{sub 3} thin films grown on Si (111) by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Borisova, S.; Kampmeier, J.; Mussler, G.; Grützmacher, D. [Peter Grünberg Institute-9, Forschungszentrum Jülich, Jülich 52425 (Germany); Jülich Aachen Research Alliance, Fundamentals of Future Information Technologies, Jülich 52425 (Germany); Luysberg, M. [Peter Grünberg Institute-5 and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Jülich 52425 (Germany)

    2013-08-19

    The atomic structure of topological insulators Bi{sub 2}Te{sub 3} thin films on Si (111) substrates grown in van der Waals mode by molecular beam epitaxy has been investigated by in situ scanning tunneling microscopy and scanning transmission electron microscopy. Besides single and multiple quintuple layer (QL) steps, which are typical for the step-flow mode of growth, a number of 0.4 QL steps is observed. We determine that these steps originate from single steps at the substrate surface causing domain boundaries in the Bi{sub 2}Te{sub 3} film. Due to the peculiar structure of these domain boundaries the domains are stable and penetrate throughout the entire film.

  3. Growth and annealing effect of SrTiO{sub 3} thin films grown by pulsed laser deposition using fourth harmonic Nd:YAG pulsed laser

    Energy Technology Data Exchange (ETDEWEB)

    Takamura, Koji; Fujiwara, Takumi; Yokota, Akinobu; Nakamura, Motonori; Yoshimoto, Ken' ichi [National Institute of Technology, Asahikawa College, 2-2-1-6 Shunkodai, Asahikawa 071-8142 (Japan)

    2017-06-15

    SrTiO{sub 3} homoepitaxial films were grown by pulsed laser deposition (PLD) using a fourth harmonic Nd:YAG pulsed laser. The substrate temperature was kept constant at 600, 700, or 800 C. The laser energy was set at 9-25 mJ on the polycrystal SrTiO{sub 3} target. Post-procedure annealing was performed in the air for 24 h. The X-ray diffraction measurement results showed that the lattice constant of the film was only 0.010 Aa larger than that of the substrate and was not dependent on the annealing temperature. We demonstrated the possibility of growing near-stoichiometric SrTiO{sub 3} film by PLD using an Nd:YAG laser. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Self-starting mode locking in a Cr:forsterite laser by use of non-epitaxially-grown semiconductor-doped silica films.

    Science.gov (United States)

    Prasankumar, R P; Chudoba, C; Fujimoto, J G; Mak, P; Ruane, M F

    2002-09-01

    We demonstrate RF sputtered, non-epitaxially-grown semiconductor nanocrystallite-doped silica films for mode locking a Cr:forsterite laser. We controlled the size and the optical properties of the nanocrystallites by varying the ratio of InAs to SiO(2) during fabrication. Femtosecond pump-probe measurements were performed to characterize the nonlinear optical properties of these films, revealing their lower saturation fluences. Using the InAs-doped silica films as saturable absorbers permitted self-starting Kerr-lens mode locking (KLM), generating pulses of 25-fs duration with 91-nm spectral bandwidth at 1.3 microm . We also describe saturable-absorber mode-locked operation without KLM and investigate its dependence on intracavity dispersion.

  5. Some optical and electron microscope comparative studies of excimer laser-assisted and nonassisted molecular-beam epitaxically grown thin GaAs films on Si

    Science.gov (United States)

    Lao, Pudong; Tang, Wade C.; Rajkumar, K. C.; Guha, S.; Madhukar, A.; Liu, J. K.; Grunthaner, F. J.

    1990-01-01

    The quality of GaAs thin films grown via MBE under pulsed excimer laser irradiation on Si substrates is examined in both laser-irradiated and nonirradiated areas using Raman scattering, Rayleigh scattering, and by photoluminescence (PL), as a function of temperature, and by TEM. The temperature dependence of the PL and Raman peak positions indicates the presence of compressive stress in the thin GaAs films in both laser-irradiated and nonirradiated areas. This indicates incomplete homogeneous strain relaxation by dislocations at the growth temperature. The residual compressive strain at the growth temperature is large enough such that even with the introduction of tensile strain arising from the difference in thermal expansion coefficients of GaAs and Si, a compressive strain is still present at room temperature for these thin GaAs/Si films.

  6. Crystalline domains in epitaxial Y(Ni0.5Mn0.5)O3 thin films grown by PLD on different STO substrates

    Science.gov (United States)

    Coy, L. E.; Rebled, J.; Ventura, J.; Yate, L.; Ferrater, C.; Langenberg, E.; Polo, M. C.; Xuriguera, E.; Peiro, F.; Varela, M.

    2015-01-01

    Thin films of ferromagnetic Y(Ni0.5Mn0.5)O3 (YNMO) perovskite were grown on different SrTiO3 (STO) substrate orientations [i.e. (0 0 1), (1 1 0) and (1 1 1)] by means of pulsed laser deposition (PLD) and their morphological and functional properties were studied and characterized. Optimal deposition parameters were identified and their individual influence on the quality of the films was also addressed. Films showed a single out-of-plane orientation in all the substrate scenarios, while the in-plane texture in STO(0 0 1) and STO(1 1 1) show two and three in plane domains, respectively. Growth mechanism and morphology were studied by HRTEM and AFM. As a result, a clear 3D growth mechanism was identified and a direct correlation between the two in-plane crystalline domains on the surface morphology of the sample was observed. Magnetic response of the films was investigated as a function of their crystalline properties. The films were found to have a paramagnetic to ferromagnetic transition around 90 K consistent with their bulk counterparts. Finally, the discrepancies on the epitaxial growth between YMnO3 (YMO) and YMNO thin films were clarified and tabulated, giving a clear picture of the effect of Ni substitution in the epitaxial and crystalline properties of manganites of this family.

  7. Effect of annealing temperature on surface morphology and ultralow ferromagnetic resonance linewidth of yttrium iron garnet thin film grown by rf sputtering

    Science.gov (United States)

    Cao Van, Phuoc; Surabhi, Srivathsava; Dongquoc, Viet; Kuchi, Rambabu; Yoon, Soon-Gil; Jeong, Jong-Ryul

    2018-03-01

    We report high-quality yttrium-iron-garnet (YIG; Y3Fe5O12) ultrathin films grown on {111} gadolinium-gallium-garnet (GGG; Gd3Ga5O12) substrates using RF sputtering deposition on an off-stoichiometric target and optimized thermal treatments. We measured a narrow peak-to-peak ferromagnetic resonance linewidth (ΔH) whose minimum value was 1.9 Oe at 9.43 GHz for a 60-nm-thick YIG film. This value is comparable to the most recently published value for a YIG thin film grown by pulsed laser deposition. The temperature dependence of the ΔH was investigated systematically, the optimal annealing condition for our growing condition was 875 °C. Structural analysis revealed that surface roughness and crystallinity played an important role in the observed ΔH broadening. Furthermore, the thickness dependence of the ΔH, which indicated that 60 nm thickness was optimal to obtain narrow ΔH YIG films, was also investigated. The thickness dependence of ΔH was understood on the basis of contributions of surface-associated magnon scattering and magnetic inhomogeneities to the ΔH broadening. Other techniques such as transmission electron microscopy, scanning electron microscopy, and X-ray diffraction were used to study the crystalline structure of the YIG films. The high quality of the films in terms of their magnetic properties was expressed through a very low coercivity and high saturation magnetization measured using a vibration sample magnetometer.

  8. Tailoring the Composition and Properties of Sprayed CuSbS2 Thin Films by Using Polymeric Additives

    Directory of Open Access Journals (Sweden)

    Ionut Popovici

    2012-01-01

    Full Text Available CuSbS2 thin films were obtained by spray pyrolysis deposition, using polymeric additives for controlling the surface properties and film’s composition. Ternary crystalline chalcostibite compounds have been obtained without any postdeposition treatments. XRD spectra and IR spectroscopy were used to characterize films composition and interactions between components. Films morphology and surface energy were investigated using AFM microscopy and contact angle measurements. Hydrophobic and hydrophilic polymers strongly influence the composition and film morphology.

  9. Properties of Ca-rich and Mg-rich carbonate films on dolomite: implications for compositional surface mapping with scanning force microscopy.

    Science.gov (United States)

    Hu, Xiaoming; Cubillas, Pablo; Higgins, Steven R

    2010-04-06

    A self-limited monolayer grown on dolomite (CaMg(CO(3))(2)), showing distinct friction contrast with the substrate as reported earlier using lateral force microscopy, was investigated with in situ atomic force microscopy (AFM) adhesion mapping and force-modulation techniques. Force-modulation microscopy revealed lower stiffness on a Ca-rich film in comparison to that on the dolomite surface. The friction contrast therefore results from a larger tip-surface contact area when the AFM probe is in contact with the Ca-rich film as opposed to the contact area with dolomite. The Ca-rich film also exhibited a slightly higher adhesion than did the dolomite substrate; however, the critical shear stresses for the two tip-surface contacts were indistinguishable. A comparative study with a Mg-rich film did not yield noticeable force modulation contrast, indicating similar surface stiffness of the film and the dolomite surface. The similarity in these stiffness quantities was further corroborated by friction-load data that demonstrated similar friction forces on the two surfaces. The previously reported film strain in the Ca-rich system is likely linked to the lower stiffness observed, with both of these properties related to the Ca/Mg composition of the film.

  10. Size-dependent structure and magnetic properties of co-evaporated Fe-SiO2 nanoparticle composite film under high magnetic field

    Directory of Open Access Journals (Sweden)

    Yonghui Ma

    2016-05-01

    Full Text Available Composite film of Fe nanoparticles embedded in a SiO2 matrix has been prepared by the co-evaporation of Fe and SiO2. Both source temperature and in-situ high magnetic field (HMF have been used to adjust the Fe particle size and the growth of Fe-SiO2 film. The size of Fe particle decreased with increasing the source temperature without HMF. When HMF was presented during the growth of the film, the size of Fe particle was enlarged and reduced for source temperatures of 1300 °C and 1400 °C, respectively. Meanwhile, the preferred orientation of the film grown at 1400 °C became uniform with the application of HMF. In addition, it is also found that the film was formed in two layers. One layer is formed by the Fe particle, while the other is free of Fe particles due to the existence of more SiO2. The structural variation has a significant effect on the magnetic properties. The coercivity (90 Oe of the 1300 °C film is much higher than that (6 Oe of the 1400 °C film with a small particle size and uniform orientation. The saturation magnetization can be increased by increasing the Fe particle volume fraction. This study develops a new method to tune the soft magnetic properties by the co-evaporation of Fe and SiO2.

  11. Effect of Continuous Multi-Walled Carbon Nanotubes on Thermal and Mechanical Properties of Flexible Composite Film

    Directory of Open Access Journals (Sweden)

    Ji Eun Cha

    2016-10-01

    Full Text Available To investigate the effect of continuous multi-walled carbon nanotubes (MWCNTs on the thermal and mechanical properties of composites, we propose a fabrication method for a buckypaper-filled flexible composite film prepared by a two-step process involving buckypaper fabrication using vacuum filtration of MWCNTs, and composite film fabrication using the dipping method. The thermal conductivity and tensile strength of the composite film filled with the buckypaper exhibited improved results, respectively 76% and 275% greater than those of the individual MWCNT-filled composite film. It was confirmed that forming continuous MWCNT fillers is an important factor which determines the physical characteristics of the composite film. In light of the study findings, composite films using buckypaper as a filler and polydimethylsiloxane (PDMS as a flexible matrix have sufficient potential to be applied as a heat-dissipating material, and as a flexible film with high thermal conductivity and excellent mechanical properties.

  12. Transparent and high gas barrier films based on poly(vinyl alcohol)/graphene oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hye Min; Lee, Jung Kyoo; Lee, Heon Sang, E-mail: heonlee@dau.ac.kr

    2011-09-01

    Composites of poly(vinyl alcohol) (PVA) and graphene oxide (GO) were synthesized by a modified Hummers method and a solution-mixing method. GO was fully exfoliated in the PVA/GO composites. GO did not affect the crystallization of PVA during solvent evaporation. GO is itself an excellent gas barrier without any chemical reduction. The oxygen permeability of the PVA/GO (0.3 wt.%) composite coated film was 17 times lower than that of the pure poly(ethylene terephthalate) (PET) film, with 92% light transmittance at 550 nm. Composites of PVA and reduced graphene oxide (RGO) were synthesized by performing chemical reduction using hydrazine monohydrate. The oxygen permeability of the PVA/RGO (0.3 wt.%) composite coated film was 86 times lower than that of the pure PET film, with 73% light transmittance at 550 nm. The reduction of oxygen permeability was mainly attributed to the reduced oxygen solubility in the PVA/GO composite film, while it was attributed to both the reduced oxygen diffusivity and solubility in the PVA/RGO composite film.

  13. Polymer compositions, polymer films and methods and precursors for forming same

    Science.gov (United States)

    Klaehn, John R; Peterson, Eric S; Orme, Christopher J

    2013-09-24

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  14. Carbon hybrid fillers composed of carbon nanotubes directly grown on graphene nanoplatelets for effective thermal conductivity in epoxy composites.

    Science.gov (United States)

    Yu, Lan; Park, Ji Sun; Lim, Yun-Soo; Lee, Churl Seung; Shin, Kwonwoo; Moon, Ho Jun; Yang, Cheol-Min; Lee, Young Sil; Han, Jong Hun

    2013-03-26

    Carbon nanomaterials are generally used to promote the thermal conductivity of polymer composites. However, individual graphene nanoplatelets (GNPs) or carbon nanotubes (CNTs) limit the realization of the desirable thermal conductivity of the composite in both through- and in-plane directions. In this work, we present the thermal conductivity enhancement of the epoxy composite with carbon hybrid fillers composed of CNTs directly grown on the GNP support. The composite with 20 wt% hybrid filler loading showed 300% and 50% through-plane thermal conductivity improvements in comparison with the individual CNTs and GNPs, respectively. Moreover, it showed an enhanced thermal conductivity of up to 12% higher than that of the simply mixed GNP and CNT fillers. In more detail, hybrid fillers, whose CNTs were synthesized on the GNP support (Support C, Fe/Mo-MgO:GNP=1:0.456) for 60 min via chemical vapor deposition process, presented the highest through-plane thermal conductivity of 2.41 W m(-1) K(-1) in an epoxy composite.

  15. Combined impact of strain and stoichiometry on the structural and ferroelectric properties of epitaxially grown N a1 +xNb O3 +δ films on (110) NdGa O3

    Science.gov (United States)

    Cai, Biya; Schwarzkopf, J.; Feldt, C.; Sellmann, J.; Markurt, T.; Wördenweber, R.

    2017-05-01

    We demonstrate that the strain of an epitaxially grown film, which is induced by the lattice mismatch between the crystalline substrate and film and relaxes with increasing film thickness, can be conserved beyond the critical thickness of plastic relaxation of the respective film/substrate heterostructure system by adding epitaxially embedded nanoprecipitates and/or nanopillars of a secondary phase. By doing so we modify the ferroelectric properties of the film in a very controlled way. For this purpose, strained N a1 +xNb O3 +δ films are epitaxially grown on (110 ) NdGa O3 and their structural and electronic properties are investigated. X-ray diffraction and transmission electron microscopy analysis indicate that in addition to the epitaxially grown majority phase NaNb O3 , a second phase N ayNb O3 +δ is present in the films and forms crystalline precipitates and vertically aligned pillars a few nanometers in diameter. For large enough concentrations, this secondary phase appears to be able to suppress the plastic relaxation of the NaNb O3 matrix. In contrast to stoichiometric films and films with small Na excess, which demonstrate strain relaxation for film thickness exceeding a few nanometers and relaxor-type ferroelectric behavior, the N a1 +xNb O3 +δ film with the largest off-stoichiometry (grown from a target with x =17 % ) exhibits the "classic" ferroelectric behavior of unstrained NaNb O3 with a hysteretic structural and ferroelectric transition. However, the temperature of this hysteretic transition is shifted from 616 K to 655 K for unstrained material to room temperature for the strained N a1 +xNb O3 +δ film grown from the off-stoichiometric target.

  16. Diatomite as a novel composite ingredient for chitosan film with enhanced physicochemical properties.

    Science.gov (United States)

    Akyuz, Lalehan; Kaya, Murat; Koc, Behlul; Mujtaba, Muhammad; Ilk, Sedef; Labidi, Jalel; Salaberria, Asier M; Cakmak, Yavuz Selim; Yildiz, Aysegul

    2017-12-01

    Practical applications of biopolymers in different industries are gaining considerable increase day by day. But still, these biopolymers lack important properties in order to meet the industrial demands. In the same regard, in the current study, chitosan composite films are produced by incorporating diatomite soil at two different concentrations. In order to obtain a homogeneous film, glutaraldehyde was supplemented to chitosan solution as a cross-linker. Compositing diatomaceous earth to chitosan film resulted in improvement of various important physicochemical properties compared to control such as; enhanced film wettability, increase elongation at break and improved thermal stability (264-277°C). The microstructure of the film was observed to haveconsisted of homogeneously distributed blister-shaped structures arised due to the incorporation of diatomite. The incorporation of diatomite did not influence the overall antioxidant activity of the composite films, which can be ascribe to the difficulty radicals formation. Chitosan film incorporated with increasing fraction of diatomite revealed a notable enhancement in the antimicrobial activity. Additionally with the present study, for the first time possible interactions between chitosan/diatomite were determined via quantum chemical calculations. Current study will be helpful in giving a new biotechnological perspective to diatom in terms of its successful application in hydrophobic composite film production. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Effect of nanoclay on optical properties of PLA/clay composite films

    CSIR Research Space (South Africa)

    Cele, HM

    2014-06-01

    Full Text Available This article reports the modification of optical properties of biodegradable/biocompatible polylactide (PLA) using organically modified montmorillonite (OMMT) for microcantilever applications. PLA/OMMT composite films with various OMMT loadings (3...

  18. Preparation and properties of biodegradable films from Sterculia urens short fiber/cellulose green composites.

    Science.gov (United States)

    Jayaramudu, J; Reddy, G Siva Mohan; Varaprasad, K; Sadiku, E R; Sinha Ray, S; Varada Rajulu, A

    2013-04-02

    The development of commercially viable "green products", based on natural resources for the matrices and reinforcements, in a wide range of applications, is on the rise. The present paper focuses on Sterculia urens short fiber reinforced pure cellulose matrix composite films. The morphologies of the untreated and 5% NaOH (alkali) treated S. urens fibers were observed by SEM. The effect of 5% NaOH treated S. urens fiber (5, 10, 15 and 20% loading) on the mechanical properties and thermal stability of the composites films is discussed. This paper presents the developments made in the area of biodegradable S. urens short fiber/cellulose (SUSF/cellulose) composite films, buried in the soil and later investigated by the (POM), before and after biodegradation has taken place. SUSF/cellulose composite films have great potential in food packaging and for medical applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. A comprehensive study of ferromagnetic resonance and structural properties of iron-rich nickel ferrite (Ni{sub x}Fe{sub 3−x}O{sub 4}, x≤1) films grown by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Pachauri, Neha; Khodadadi, Behrouz [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Singh, Amit V. [Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Mohammadi, Jamileh Beik [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Martens, Richard L. [Central Analytical Facility (CAF), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); LeClair, Patrick R.; Mewes, Claudia; Mewes, Tim [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Gupta, Arunava [Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States)

    2016-11-01

    We report a detailed study of the structural and ferromagnetic resonance properties of spinel nickel ferrite (NFO) films, grown on (100)-oriented cubic MgAl{sub 2}O{sub 4} substrates by direct liquid injection chemical vapor deposition (DLI-CVD) technique. Three different compositions of NFO films (Ni{sub x}Fe{sub 3−x}O{sub 4} where x=1, 0.8, 0.6) deposited at optimized growth temperature of 600 °C are characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometry (VSM), and broadband ferromagnetic resonance (FMR) techniques. XRD confirms the growth of epitaxial, single crystalline Ni{sub x}Fe{sub 3−x}O{sub 4} films. The out-of-plane lattice constant (c) obtained for Ni{sub 0.8}Fe{sub 2.2}O{sub 4} film is slightly higher than the bulk value (0.833 nm), indicating only partial strain relaxation whereas for the other two compositions (x=1 and x=0.6) films exhibit complete relaxation. The in-plane and out-of-plane FMR linewidths measurements at 10 GHz give the lowest values of 458 Oe and 98 Oe, respectively, for Ni{sub 0.8}Fe{sub 2.2}O{sub 4} film as compared to the other two compositions. A comprehensive frequency (5–40 GHz) and temperature (10–300 K) dependent FMR study of the Ni{sub 0.8}Fe{sub 2.2}O{sub 4} sample for both in-lane and out-of-plane configurations reveals two magnon scattering (TMS) as the dominant in-plane relaxation mechanism. It is observed that the TMS contribution to the FMR linewidth scales with the saturation magnetization M{sub s}. In-plane angle-dependent FMR measurements performed on the same sample show that the ferromagnetic resonance field (H{sub res}) and the FMR linewidth (ΔH) have a four-fold symmetry that is consistent with the crystal symmetry of the spinel. SEM measurements show formation of pyramid-like microstructures at the surface of the Ni{sub 0.8}Fe{sub 2.2}O{sub 4} sample, which can explain the observed four-fold symmetry of the FMR linewidth.

  20. The effect of deposition parameters on the boron nitride films grown on Si(100) by PLD with nanosecond pulses

    Science.gov (United States)

    Luculescu, C. R.; Sato, Shunichi; Fenic, Constantin G.

    2004-10-01

    The effects of several deposition parameters on the quality of deposited boron nitride (BN) films by pulsed laser deposition (PLD) with short laser pulses are studied. The laser fluence, nitrogen background pressure, Si(100) substrate temperature and laser wavelength were varied in order to find the maximum content of the cubic phase in our BN films. We found that laser fluence and wavelength are affecting strongly the structure of BN films while background pressure and substrate temperature are affecting slightly the film morphology.

  1. Compositional uniformity of a Si0.5Ge0.5 crystal grown on board the International Space Station

    Science.gov (United States)

    Kinoshita, K.; Arai, Y.; Inatomi, Y.; Tsukada, T.; Miyata, H.; Tanaka, R.; Yoshikawa, J.; Kihara, T.; Tomioka, H.; Shibayama, H.; Kubota, Y.; Warashina, Y.; Ishizuka, Y.; Harada, Y.; Wada, S.; Ito, T.; Nagai, N.; Abe, K.; Sumioka, S.; Takayanagi, M.; Yoda, S.

    2015-06-01

    A Si0.5Ge0.5 crystal was grown on board the International Space Station (ISS) using the traveling liquidus-zone method. Average Ge concentration was 49±2 at% for the growth length of 14.5 mm. Radial compositional uniformity was excellent especially between the growth length of 3 and 9 mm; concentration fluctuation was less than 1 at%. In this experiment, cartridge surface temperatures were monitored and heater temperatures were adjusted based on the monitored temperatures for improving compositional uniformity of a grown crystal. A step temperature change by 1 °C was imposed for adjusting heater temperatures. This procedure made it possible to observe growth interface shape; striations due to heater temperature change were observed by a backscattered electron image. Growth rates were precisely determined by the relation between interval of heater temperature change and the distance between striations. Based on the measured growth rates, two-dimensional growth model for the traveling liquidus-zone method was discussed.

  2. Synthesis of TiO 2-doped SiO 2 composite films and its applications

    Indian Academy of Sciences (India)

    The TiO2-doped SiO2 composite films were prepared by two-step sol–gel method and then it was applied in the degradation of methylene red (MR) as photocatalysts. In XRD, FT–IR, and TEM investigations of these TiO2-doped SiO2 composite films, the titanium oxide species are highly dispersed in the SiO2 matrixes and ...

  3. A dense and strong bonding collagen film for carbon/carbon composites

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Sheng; Li, Hejun, E-mail: lihejun@nwpu.edu.cn; Li, Kezhi; Lu, Jinhua; Zhang, Leilei

    2015-08-30

    Graphical abstract: - Highlights: • Significantly enhancement of biocompatibility on C/C composites by preparing a collagen film. • The dense and continuous collagen film had a strong bonding strength with C/C composites after dehydrathermal treatment (DHT) crosslink. • Numerous oxygen-containing functional groups formed on the surface of C/C composites without matrix damage. - Abstract: A strong bonding collagen film was successfully prepared on carbon/carbon (C/C) composites. The surface conditions of the modified C/C composites were detected by contact angle measurements, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectra. The roughness, optical morphology, bonding strength and biocompatibility of collagen films at different pH values were detected by confocal laser scanning microscope (CLSM), universal test machine and cytology tests in vitro. After a 4-h modification in 30% H{sub 2}O{sub 2} solution at 100 °C, the contact angle on the surface of C/C composites was decreased from 92.3° to 65.3°. Large quantities of hydroxyl, carboxyl and carbonyl functional groups were formed on the surface of the modified C/C composites. Then a dense and continuous collagen film was prepared on the modified C/C substrate. Bonding strength between collagen film and C/C substrate was reached to 8 MPa level when the pH value of this collagen film was 2.5 after the preparing process. With 2-day dehydrathermal treatment (DHT) crosslinking at 105 °C, the bonding strength was increased to 12 MPa level. At last, the results of in vitro cytological test showed that this collagen film made a great improvement on the biocompatibility on C/C composites.

  4. Amino Acid Composition of Bulk Protein of Euglena Grown in Waste Water

    Science.gov (United States)

    Kott, Yehuda; Wachs, A. M.

    1964-01-01

    The amino acid content of bulk protein in a sewage-grown Euglena sp. was examined. Concentrations of the essential amino acids, threonine, histidine, tryptophan, and valine, were similar to those found in other algae. The concentration of alanine was much higher. Methionine was not found at all, proline only in traces, and other amino acids at low concentrations. These results indicate that the amino acid content of bulk protein of the species of Euglena studied resembles that of plants far more closely than that of animals. PMID:14199015

  5. AMINO ACID COMPOSITION OF BULK PROTEIN OF EUGLENA GROWN IN WASTE WATER.

    Science.gov (United States)

    KOTT, Y; WACHS, A M

    1964-07-01

    The amino acid content of bulk protein in a sewage-grown Euglena sp. was examined. Concentrations of the essential amino acids, threonine, histidine, tryptophan, and valine, were similar to those found in other algae. The concentration of alanine was much higher. Methionine was not found at all, proline only in traces, and other amino acids at low concentrations. These results indicate that the amino acid content of bulk protein of the species of Euglena studied resembles that of plants far more closely than that of animals.

  6. Investigation of polypyrrole/polyvinyl alcohol–titanium dioxide composite films for photo-catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long, E-mail: jianglong@scu.edu.cn; Dan, Yi, E-mail: danyichenweiwei@163.com

    2015-07-01

    Graphical abstract: - Highlights: • The study provides an easy and convenient method to fabricate films, which will give guidance for the preparation of three-dimensional materials. • The PPy/PVA–TiO{sub 2} films can keep better photo-catalytic activities both under UV and visible light irradiation when compared with TiO{sub 2} film. • There exist electron transfers between PPy/PVA and TiO{sub 2}. - Abstract: Polypyrrole/polyvinyl alcohol–titanium dioxide (PPy/PVA–TiO{sub 2}) composite films used as photo-catalysts were fabricated by combining TiO{sub 2} sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet–visible diffuse reflection spectroscopy (UV–vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO{sub 2} and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet–vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA–TiO{sub 2} composite films show better photo-catalytic properties than TiO{sub 2} film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA–TiO{sub 2} composite film was investigated and the results show that

  7. The influence of oxygen flow rate on properties of SnO{sub 2} thin films grown epitaxially on c-sapphire by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Y.M. [I. Physics Institute, Justus-Liebig University of Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei University (China); Key Laboratory of Green Preparation and Application for Functional Materials, Ministry of Education, Hubei University (China); Faculty of Materials Science & Engineering, Hubei University (China); Jiang, J. [I. Physics Institute, Justus-Liebig University of Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany); Xia, C. [Physical Chemistry Institute, Justus-Liebig University of Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen (Germany); Kramm, B.; Polity, A. [I. Physics Institute, Justus-Liebig University of Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany); He, Y.B., E-mail: ybhe@hubu.edu.cn [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei University (China); Key Laboratory of Green Preparation and Application for Functional Materials, Ministry of Education, Hubei University (China); Faculty of Materials Science & Engineering, Hubei University (China); Klar, P.J.; Meyer, B.K. [I. Physics Institute, Justus-Liebig University of Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany)

    2015-11-02

    Tin dioxide (SnO{sub 2}) thin films were grown on c-plane sapphire substrates by chemical vapor deposition using SnI{sub 2} and O{sub 2} as reactants. The growth experiments were carried out at a fixed substrate temperature of 510 °C and different O{sub 2} flow rates. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, UV–Vis–IR spectrophotometry and Hall-effect measurement were used to characterize the films. All films consisted of pure-phase SnO{sub 2} with a rutile structure and showed an epitaxial relationship with the substrate of SnO{sub 2}(100)||Al{sub 2}O{sub 3}(0001) and SnO{sub 2}[010]||Al{sub 2}O{sub 3}< 11–20 >. The crystalline quality and properties of the films were found to be sensitively dependent on the O{sub 2} flow rate during the film growth. The absolute average transmittance of the SnO{sub 2} films exceeded 85% in the visible and infrared spectral region. The films had optical band-gaps (3.72–3.89 eV) that are in line with the band gap of single-crystal SnO{sub 2}. The carrier concentration and Hall mobility of the films decreased from 3.3 × 10{sup 19} to 9 × 10{sup 17} cm{sup −3} and from 19 to 2 cm{sup 2} V{sup −1} s{sup −1}, respectively, while the resistivity increased from 0.01 to 3 Ω cm with increasing of the O{sub 2} flow rate from 5 to 60 sccm. - Highlights: • SnI{sub 2} (Sn{sup 2+}) was used as tin precursor to prepare tin oxide films by CVD. • Epitaxial SnO{sub 2} (100) films were obtained on c-sapphire with thickness more than 1 μm. • The epitaxial relationship is SnO{sub 2}(100)||Al{sub 2}O{sub 3}(0001) and SnO{sub 2}[010]||Al{sub 2}O{sub 3}< 11–20 >. • B{sub 2g} Raman mode was found to be absent in (100)-orientated SnO{sub 2} films on c-sapphire. • The crystal quality and properties of SnO{sub 2} films depended sensitively on the O{sub 2} flow rate.

  8. Preventing phase separation in MOCVD-grown InAlAs compositionally graded buffer on silicon substrate using InGaAs interlayers

    Science.gov (United States)

    Kohen, David; Nguyen, Xuan Sang; Made, Riko I.; Heidelberger, Christopher; Lee, Kwang Hong; Lee, Kenneth Eng Kian; Fitzgerald, Eugene A.

    2017-11-01

    Compositionally graded InAlAs buffers grown by metal-organic chemical vapor deposition are impaired by phase separation occurring at In content higher than 35%. Phase separation results in rough epilayers with poor crystalline material quality. By introducing low temperature grown InGaAs interlayers in the compositionally graded InAlAs buffer, the surface roughness decreases, allowing a grading of up to In0.60Al0.40As without any phase separation occurring. This composite buffer is applied to fabricate a 200 mm diameter InP-on-Si virtual substrate with a threading dislocation density around 1 × 108 cm-2.

  9. Anodic luminescence, structural, photoluminescent, and photocatalytic properties of anodic oxide films grown on niobium in phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Tadić, Nenad [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Radić, Nenad [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Stefanov, Plamen [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, 1113 Sofia (Bulgaria); Grbić, Boško [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Vasilić, Rastko [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia)

    2015-11-15

    Graphical abstract: - Highlights: • Anodic luminescence is correlated to the existence of morphological defects in the oxide. • Spectrum under spark discharging reveals only oxygen and hydrogen lines. • Oxide films formed under spark discharging are crystallized and composed of Nb{sub 2}O{sub 5}. • Photocatalytic activity and photoluminescence of Nb{sub 2}O{sub 5} films increase with time. - Abstract: This article reports on properties of oxide films obtained by anodization of niobium in phosphoric acid before and after the dielectric breakdown. Weak anodic luminescence of barrier oxide films formed during the anodization of niobium is correlated to the existence of morphological defects in the oxide layer. Small sized sparks generated by dielectric breakdown of formed oxide film cause rapid increase of luminescence intensity. The luminescence spectrum of obtained films on niobium under spark discharging is composed of continuum radiation and spectral lines caused by electronic spark discharging transitions in oxygen and hydrogen atoms. Oxide films formed before the breakdown are amorphous, while after the breakdown oxide films are partly crystalline and mainly composed of Nb{sub 2}O{sub 5} hexagonal phase. The photocatalytic activity of obtained oxide films after the breakdown was investigated by monitoring the degradation of methyl orange. Increase of the photocatalytic activity with time is related to an increase of oxygen vacancy defects in oxide films formed during the process. Also, higher concentration of oxygen vacancy defects in oxide films results in higher photoluminescence intensity.

  10. Properties of ZnO thin films grown at room temperature by using ionized cluster beam deposition

    CERN Document Server

    Whangbo, S W; Kim, S G; Cho, M H; Jeong, K H; Whang, C N

    2000-01-01

    ZnO films with a thickness of 120 nm were deposited on Si(100) at room temperature by using the reactive-ionized cluster beam deposition technique. The effects of the acceleration voltage (V sub a) on the properties, such as the crystallinity, the induced film strain, the surface roughness, and the electrical and the optical properties of the films, were investigated. The ZnO films had only a (002) crystalline orientation and uniformly composed through the whole thickness. As the V sub a increased, more strain was induced in the film, and the packing density caused by the structural imperfection was lowered. The films prepared under the optimum condition (V sub a = 3 kV) on a glass substrate showed good optical transmittance, and the band-gap of the film was evaluated to be 3.32 eV.

  11. Tunable optical properties of laser grown double-structures with gold nanoparticles and zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gyoergy, E. [National Institute for Lasers, Plasma and Radiations Physics, P.O. Box MG 54, 77125 Bucharest (Romania); Consejo Superior de Investigaciones Cientificas, Instituto de Ciencia de Materiales de Barcelona (Spain); Consejo Superior de Investigaciones Cientificas, Instituto de Ciencia de Materiales de Barcelona (ICMAB-CSIC), Bellaterra (Spain); Perez del Pino, A. [Consejo Superior de Investigaciones Cientificas, Instituto de Ciencia de Materiales de Barcelona (ICMAB-CSIC), Bellaterra (Spain); Giannoudakos, A.; Kompitsas, M. [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, Vasileos Konstantinou Ave. 48, 11635 Athens (Greece); Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiations Physics, P.O. Box MG 54, 77125 Bucharest (Romania)

    2008-08-15

    Gold nanoparticles on zinc oxide thin films surfaces have been synthesized by means of two step pulsed laser deposition. Zinc and gold targets were subsequently submitted to pulses generated by an UV KrF*({lambda}=248 nm, {tau}{sub FWHM}{approx_equal}20 ns, {nu}=2 Hz) excimer, as well as a frequency tripled Nd:YAG ({lambda}=355 nm, {tau}{proportional_to}10 ns) laser sources. The obtained structures surface morphology, crystalline quality, and chemical composition depth profile were investigated by acoustic (dynamic) mode atomic force microscopy, X-ray diffraction, and wavelength dispersive X-ray spectroscopy. The corresponding absorption and reflection spectra were recorded with the aid of a double beam spectrophotometer. The results proved the possibility to tailor the gold/zinc oxide nanostructures optical properties through the proper choice of the growth parameters, i.e. number of laser pulses used for the ablation of the gold targets as well as nature of the substrate material. The tunable optical features in the visible-near infrared spectral region allow for the design of gold/zinc oxide nanostructures with pre-defined optical characteristics. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. P-type nitrogen- and phosphorus-doped ZnO thin films grown by pulsed laser deposition on sapphire substrates

    Science.gov (United States)

    Mosnier, J.-P.; Chakrabarti, S.; Doggett, B.; McGlynn, E.; Henry, M. O.; Meaney, A.

    2007-02-01

    Nitrogen- and phosphorus-doped ZnO thin films were grown by pulsed laser deposition using an electron cyclotron resonance (ECR) nitrogen plasma ion source or a ZnO:P IIO 5 doped target, as the dopant source, respectively. Both types of films were grown on sapphire substrates first coated at low temperature with a ZnO buffer layer. For the N-doped ZnO thin films, temperature-dependent Van der Pauw measurements showed consistent p-type behavior over the measured temperature range of 200-450 K, with typical room temperature acceptor concentrations and mobilities of 5 x 10 15 cm -3 and 5.61 cm2/Vs, respectively. The room-temperature photoluminescence spectrum of a N-doped ZnO thin film featured a broad near band-edge emission at about 3.1 eV photon energy with a width of 0.5 eV. XPS studies confirmed the incorporation of nitrogen in the samples. The ZnO:P layers (with phosphorus concentrations of between 0.01 and 1 wt %) typically showed weak n-type conduction in the dark, with a resistivity of 70 Ω.cm, a Hall mobility of μ n ~ 0.5 cm2V -1s -1 and a carrier concentration of n ~ 3 x 10 17 cm -3 at room temperature. After exposure to an incandescent light source, the samples underwent a change from n- to p-type conduction, with an increase in mobility and a decrease in concentration for temperatures below 300K. Electrical measurements showed noticeable differences for both types of doped films when carried out in air or in vacuum. The results are discussed in terms of both the presence of surface conducting channels and the influence of photoconductive effects.

  13. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Structural and Electrical Properties of Single Crystalline Ga-Doped ZnO Thin Films Grown by Molecular Beam Epitaxy

    Science.gov (United States)

    Lu, Zhong-Lin; Zou, Wen-Qin; Xu, Ming-Xiang; Zhang, Feng-Ming; Du, You-Wei

    2009-11-01

    High-quality Ga-doped ZnO (ZnO:Ga) single crystalline films with various Ga concentrations are grown on a-plane sapphire substrates using molecular-beam epitaxy. The site configuration of doped Ga atoms is studied by means of x-ray absorption spectroscopy. It is found that nearly all Ga can substitute into ZnO lattice as electrically active donors, a generating high density of free carriers with about one electron per Ga dopant when the Ga concentration is no more than 2%. However, further increasing the Ga doping concentration leads to a decrease of the conductivity due to partial segregation of Ga atoms to the minor phase of the spinel ZnGa2O4 or other intermediate phase. It seems that the maximum solubility of Ga in the ZnO single crystalline film is about 2 at.% and the lowest resistivity can reach 1.92 × 10-4 Ω·cm at room temperature, close to the best value reported. In contrast to ZnO:Ga thin film with 1% or 2% Ga doping, the film with 4% Ga doping exhibits a metal semiconductor transition at 80 K. The scattering mechanism of conducting electrons in single crystalline ZnO:Ga thin film is discussed.

  14. Annealing effect on properties of BaWO4:Eu3+ phosphor thin films grown on glass substrates by radio-frequency magnetron sputtering

    Science.gov (United States)

    Cho, Shinho

    2018-02-01

    The effects of the rapid thermal annealing (RTA) temperature on the properties of BaWO4:Eu3+ phosphor thin films grown on glass substrates by radio-frequency magnetron sputtering were investigated. The deposited phosphor thin films were annealed at several RTA temperatures for 30 min. The experimental results show that the crystalline phase, surface morphology, transmittance, optical band gap, and photoluminescence intensity depended strongly on the RTA temperature. A preferential orientation along (112) plane and grains with an average size of 40 nm were observed for a thin film annealed at 400 °C. As the annealing temperature increased, the average transmittance in the wavelength range of 400-1100 nm gradually increased, reaching a maximum of 90.8% at 550 °C, where the highest optical band gap of 3.98 eV was obtained. The dominant emission spectra of the BaWO4:Eu3+ phosphor thin films under excitation at 323 nm, regardless of the RTA temperature, exhibited an emission band at 622 nm arising from the 5D0 → 7F2 transition of Eu3+ ions, indicating that the Eu3+ ions in the BaWO4 host lattice were located at sites without inversion symmetry. The results suggest that the optimum annealing temperature for fabricating highly luminescent red-emitting phosphor thin films is 500 °C.

  15. Mapping the 3D distribution of CdSe nanocrystals in highly oriented and nanostructured hybrid P3HT-CdSe films grown by directional epitaxial crystallization.

    Science.gov (United States)

    Roiban, L; Hartmann, L; Fiore, A; Djurado, D; Chandezon, F; Reiss, P; Legrand, J-F; Doyle, S; Brinkmann, M; Ersen, O

    2012-11-21

    Highly oriented and nanostructured hybrid thin films made of regioregular poly(3-hexylthiophene) and colloidal CdSe nanocrystals are prepared by a zone melting method using epitaxial growth on 1,3,5-trichlorobenzene oriented crystals. The structure of the films has been analyzed by X-ray diffraction using synchrotron radiation, electron diffraction and 3D electron tomography to afford a multi-scale structural and morphological description of the highly structured hybrid films. A quantitative analysis of the reconstructed volumes based on electron tomography is used to establish a 3D map of the distribution of the CdSe nanocrystals in the bulk of the films. In particular, the influence of the P3HT-CdSe ratio on the 3D structure of the hybrid layers has been analyzed. In all cases, a bi-layer structure was observed. It is made of a first layer of pure oriented semi-crystalline P3HT grown epitaxially on the TCB substrate and a second P3HT layer containing CdSe nanocrystals uniformly distributed in the amorphous interlamellar zones of the polymer. The thickness of the P3HT layer containing CdSe nanoparticles increas