WorldWideScience

Sample records for bi-layer films evaporated

  1. Microstructure and mechanical behavior of a shape memory Ni-Ti bi-layer thin film

    International Nuclear Information System (INIS)

    Two different single-layers and a bi-layer Ni-Ti thin films with chemical compositions of Ni45Ti50Cu5, Ni50.8Ti49.2 and Ni50.8Ti49.2/Ni45Ti50Cu5 (numbers indicate at.%) determined by energy dispersive X-ray spectroscopy were deposited on Si (111) substrates using DC magnetron sputtering. The structures, surface morphology and transformation temperatures of annealed thin films at 500 °C for 15 min and 1 h were studied using grazing incidence X-ray diffraction, transmission electron microscopy (TEM), atomic force microscopy and differential scanning calorimetry (DSC), respectively. Nanoindentation was used to characterize the mechanical properties. The DSC and X-ray diffraction results indicated the austenitic structure of the Ni50.8Ti49.2 and martensitic structure of the Ni45Ti50Cu5 thin films while the bi-layer was composed of austenitic and martensitic thin films. TEM study revealed that copper encourages crystallization in the bi-layer such that crystal structure containing nano-precipitates in the Ni45Ti50Cu5 layer was detected after 15 min annealing while the Ni50.8Ti49.2 layer crystallized after 60 min at 500 °C. Furthermore, after annealing at 500 °C for 15 min, a precipitate free zone and thin layer amorphous were observed closely to the interface in the top layer. The bi-layer was completely crystallized at 500 °C for 1 h and the orientation of the Ni-rich precipitates indicated a stress gradient in the bi-layer. The bi-layer thin film showed different transformation temperatures and mechanical behavior from the single-layers. The developed bi-layer has different phase transformation temperatures, the higher temperatures of shape memory effect and lower temperature of pseudo-elastic behavior compared to the single-layers. Also, the bi-layer thin film exhibited a combined pseudo-elastic behavior and shape memory effect with a reduced hysteresis at the same time similar to the austenitic and martensitic thin films, respectively. - Highlights: • NiTi bi-layer

  2. Bi-layer functionally gradient thick film semiconducting methane sensors

    Indian Academy of Sciences (India)

    A Banerjee; A K Haldar; J Mondal; A Sen; H S Maiti

    2002-11-01

    Gas sensors based on metal oxide semiconductors like tin dioxide are widely used for the detection of toxic and combustible gases like carbon monoxide, methane and LPG. One of the problems of such sensors is their lack of sensitivity, which to some extent, can be circumvented by using different catalysts. However, highly reactive volatile organic compounds (VOC) coming from different industrial and domestic products (e.g. paints, lacquers, varnishes etc) can play havoc on such sensors and can give rise to false alarms. Any attempt to adsorb such VOCs (e.g. by using activated charcoal) results in sorption of the detecting gases (e.g. methane) too. To get round the problem, bi-layer sensors have been developed. Such tin oxide based functionally gradient bi-layer sensors have different compositions at the top and bottom layers. Here, instead of adsorbing the VOCs, they are allowed to interact and are consumed on the top layer of the sensors and a combustible gas like methane being less reactive, penetrates the top layer and interacts with the bottom layer. By modifying the chemical compositions of the top and bottom layers and by designing the electrode-lead wire arrangement properly, the top layer can be kept electrically shunted from the bottom layer and the electrical signal generated at the bottom layer from the combustible gas is collected. Such functionally gradient sensors, being very reliable, can find applications in domestic, industrial and strategic sectors.

  3. Microstructure and mechanical behavior of a shape memory Ni-Ti bi-layer thin film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Nili-Ahmadabadi, Mahmoud, E-mail: nili@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, University of Tehran, Tehran (Iran, Islamic Republic of); Ivanisenko, Julia [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Schwaiger, Ruth [Karlsruhe Institute of Technology, Institute for Applied Materials, 76021 Karlsruhe (Germany); Hahn, Horst; Chakravadhanula, Venkata Sai Kiran [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany)

    2015-05-29

    Two different single-layers and a bi-layer Ni-Ti thin films with chemical compositions of Ni{sub 45}Ti{sub 50}Cu{sub 5}, Ni{sub 50.8}Ti{sub 49.2} and Ni{sub 50.8}Ti{sub 49.2}/Ni{sub 45}Ti{sub 50}Cu{sub 5} (numbers indicate at.%) determined by energy dispersive X-ray spectroscopy were deposited on Si (111) substrates using DC magnetron sputtering. The structures, surface morphology and transformation temperatures of annealed thin films at 500 °C for 15 min and 1 h were studied using grazing incidence X-ray diffraction, transmission electron microscopy (TEM), atomic force microscopy and differential scanning calorimetry (DSC), respectively. Nanoindentation was used to characterize the mechanical properties. The DSC and X-ray diffraction results indicated the austenitic structure of the Ni{sub 50.8}Ti{sub 49.2} and martensitic structure of the Ni{sub 45}Ti{sub 50}Cu{sub 5} thin films while the bi-layer was composed of austenitic and martensitic thin films. TEM study revealed that copper encourages crystallization in the bi-layer such that crystal structure containing nano-precipitates in the Ni{sub 45}Ti{sub 50}Cu{sub 5} layer was detected after 15 min annealing while the Ni{sub 50.8}Ti{sub 49.2} layer crystallized after 60 min at 500 °C. Furthermore, after annealing at 500 °C for 15 min, a precipitate free zone and thin layer amorphous were observed closely to the interface in the top layer. The bi-layer was completely crystallized at 500 °C for 1 h and the orientation of the Ni-rich precipitates indicated a stress gradient in the bi-layer. The bi-layer thin film showed different transformation temperatures and mechanical behavior from the single-layers. The developed bi-layer has different phase transformation temperatures, the higher temperatures of shape memory effect and lower temperature of pseudo-elastic behavior compared to the single-layers. Also, the bi-layer thin film exhibited a combined pseudo-elastic behavior and shape memory effect with a reduced

  4. Study of Sb/SnO2 bi-layer films prepared by ion beam sputtering deposition technique

    International Nuclear Information System (INIS)

    In the present work, bi-layer thin films of Sb/SnO2 were produced on unheated glass substrates using ion beam sputtering (IBS) technique without post annealing treatment. The thickness of Sb layers was varied from 2 to 10 nm and the Sb layers were deposited on SnO2 layers having thicknesses of 40 nm to 115 nm. The effect of thickness was studied on the morphological, electrical and optical properties. The Sb/SnO2 bi-layer resulted in lowering the electrical resistivity as well as reducing the optical transmittance. However, the optical and electrical properties of the bi-layer films were mainly influenced by the thickness of Sb layers due to progressive transfer in structures from aggregate to continuous films. The bi-layer films show the electrical resistivity of 1.4 × 10−3 Ω cm and an optical transmittance of 26% for Sb film having 10 nm thickness. - Highlights: • Bi-layer Sb/SnO2 structures were synthesized by ion beam sputtering (IBS) technique. • The 6 nm-thick Sb film is a transition region in this study. • The conductivity of the bi-layer films is increased as Sb thickness increases. • The transmittance of the bi-layer films is decreased as Sb thickness increases

  5. Crystallization study of amorphous sputtered NiTi bi-layer thin film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam, E-mail: mmohri@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Nili-Ahmadabadi, Mahmoud [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, University of Tehran, Tehran (Iran, Islamic Republic of); Chakravadhanula, Venkata Sai Kiran [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany)

    2015-05-15

    The crystallization of Ni-rich/NiTiCu bi-layer thin film deposited by magnetron sputtering from two separate alloy targets was investigated. To achieve the shape memory effect, the NiTi thin films deposited at room temperature with amorphous structure were annealed at 773 K for 15, 30, and 60 min for crystallization. Characterization of the films was carried out by differential scanning calorimetry to indicate the crystallization temperature, grazing incidence X-ray diffraction to identify the phase structures, atomic force microscopy to evaluate surface morphology, scanning transmission electron microscopy to study the cross section of the thin films. The results show that the structure of the annealed thin films strongly depends on the temperature and time of the annealing. Crystalline grains nucleated first at the surface and then grew inward to form columnar grains. Furthermore, the crystallization behavior was markedly affected by composition variations. - Highlights: • A developed bi-layer Ni45TiCu5/Ni50.8Ti was deposited on Si substrate and crystallized. • During crystallization, The Ni{sub 45}TiCu{sub 5} layer is thermally less stable than the Ni-rich layer. • The activation energy is 302 and 464 kJ/mol for Cu-rich and Ni-rich layer in bi-layer, respectively.

  6. Crystallization study of amorphous sputtered NiTi bi-layer thin film

    International Nuclear Information System (INIS)

    The crystallization of Ni-rich/NiTiCu bi-layer thin film deposited by magnetron sputtering from two separate alloy targets was investigated. To achieve the shape memory effect, the NiTi thin films deposited at room temperature with amorphous structure were annealed at 773 K for 15, 30, and 60 min for crystallization. Characterization of the films was carried out by differential scanning calorimetry to indicate the crystallization temperature, grazing incidence X-ray diffraction to identify the phase structures, atomic force microscopy to evaluate surface morphology, scanning transmission electron microscopy to study the cross section of the thin films. The results show that the structure of the annealed thin films strongly depends on the temperature and time of the annealing. Crystalline grains nucleated first at the surface and then grew inward to form columnar grains. Furthermore, the crystallization behavior was markedly affected by composition variations. - Highlights: • A developed bi-layer Ni45TiCu5/Ni50.8Ti was deposited on Si substrate and crystallized. • During crystallization, The Ni45TiCu5 layer is thermally less stable than the Ni-rich layer. • The activation energy is 302 and 464 kJ/mol for Cu-rich and Ni-rich layer in bi-layer, respectively

  7. A novel phase modulation-based system using bi-layer thin film displacement sensors

    Energy Technology Data Exchange (ETDEWEB)

    Meydan, T. [Wolfson Centre for Magnetics, Cardiff University, Queens Buildings, Newport Road, Cardiff CF24 3AA (United Kingdom)]. E-mail: Meydan@cf.ac.uk; Katranas, G.S. [Wolfson Centre for Magnetics, Cardiff University, Queens Buildings, Newport Road, Cardiff CF24 3AA (United Kingdom); Ovari, T.A. [Wolfson Centre for Magnetics, Cardiff University, Queens Buildings, Newport Road, Cardiff CF24 3AA (United Kingdom); Borza, F. [Wolfson Centre for Magnetics, Cardiff University, Queens Buildings, Newport Road, Cardiff CF24 3AA (United Kingdom)

    2007-03-15

    A novel method has been used for accurately measuring low-voltage signals ({approx}10{sup -4} V) associated with inductance changes of bi-layer thin-film sensors under bending stress. Bi-layer sensors consist of a magnetic layer and a non-magnetic counter layer that is used to enhance the changes in the relative permeability of the material, caused by tensile or compressive stresses. The measuring system utilizes a personal computer-based system using the LabVIEW[reg] graphical programming package. The results from the acquisition proved that this system provided a robust, cost-effective solution (as compared to hardware-based systems) to evaluate magnetostrictive materials and their application in magnetic sensors.

  8. A novel phase modulation-based system using bi-layer thin film displacement sensors

    International Nuclear Information System (INIS)

    A novel method has been used for accurately measuring low-voltage signals (∼10-4 V) associated with inductance changes of bi-layer thin-film sensors under bending stress. Bi-layer sensors consist of a magnetic layer and a non-magnetic counter layer that is used to enhance the changes in the relative permeability of the material, caused by tensile or compressive stresses. The measuring system utilizes a personal computer-based system using the LabVIEW[reg] graphical programming package. The results from the acquisition proved that this system provided a robust, cost-effective solution (as compared to hardware-based systems) to evaluate magnetostrictive materials and their application in magnetic sensors

  9. Composite bi-layered erodible films for potential ocular drug delivery.

    Science.gov (United States)

    Boateng, J S; Popescu, A M

    2016-09-01

    Bi-layered hydroxypropylmethylcellulose and Eudragit based films were formulated as potential ocular drug delivery systems using chloramphenicol as a model antibiotic. Films were plasticized with polyethylene glycol 400 present in the Eudragit layer or both Eudragit and hydroxypropylmethylcellulose layers, and loaded with chloramphenicol (0.5% w/v in solution) in the hydroxypropylmethylcellulose layer. The weight, thickness and folding endurance of the optimized formulations were measured and further characterised for transparency, tensile, mucoadhesive, swelling and in vitro drug dissolution properties. The physical form of chloramphenicol within the films was evaluated using differential scanning calorimetry (DSC), and X-ray diffraction (XRD), complimented with scanning electron microscopy and energy dispersive X-ray spectroscopy. Fourier transform infrared spectroscopy was used to assess the interactions between the drug and the film components and confirm chloramphenicol's presence within the sample. Optimum films showed high transparency (≥80% transmittance), ease of peeling from Petri dish and folding endurance above 250. Average thickness was lower than contact lenses (0.4-1mm), confirming them as thin ocular films. The tensile properties showed a good balance between toughness and flexibility, and mucoadhesivity showed that they could potentially adhere to the ocular surface for prolonged periods. The drug loaded films showed swelling capacity that was greater than 300% of their original weight. The physical form of chloramphenicol within the films was amorphous (DSC and XRD) whilst in vitro drug dissolution showed sustained drug release from the films for four hours, before complete erosion. The chloramphenicol loaded films represent a potential means of treating common eye infections. PMID:27214785

  10. Characteristics of IZO/AZO and AZO/IZO Bi-layer transparent conducting thin films prepared by using PLD

    International Nuclear Information System (INIS)

    AZO/IZO and IZO/AZO bi-layer thin films were deposited on the glass substrates by using pulsed laser deposition (PLD). The crystallinity and the texture of the thin film depend on the sequence of deposition of the IZO layer and the AZO layer. The crystal structures, the electrical and optical properties of the AZO/IZO and the IZO/AZO thin film were analyzed and compared using X-ray diffraction, field-emission scanning electron microscope, Hall measurements and UV spectrometry. The IZO/AZO bi-layer thin film showed a highly-oriented texture of IZO along the axis, which implied that the c-axis-oriented AZO buffer layer enhanced the tendency of the IZO thin film to grow preferentially along the axis. On the other hand, the AZO/IZO thin film did not revealed oriented grain growth of the AZO layer, which indicated that randomly-oriented IZO buffer layer suppressed the tendency of the AZO thin film to grow preferentially along the c-axis. The AZO/IZO and the IZO/AZO bi-layer thin films showed the average values of the AZO and the IZO monolayers for the electrical resistivity and the optical band gap.

  11. Performance enhancement of thin-film ceramic electrolyte fuel cell using bi-layered yttrium-doped barium zirconate

    International Nuclear Information System (INIS)

    A thin-film yttrium-doped barium zirconate comprised of two distinct layers with different porosity was fabricated by pulsed laser deposition method for a low-temperature solid oxide fuel cell electrolyte to enhance electrode reactions and suppress electric short-circuit problem simultaneously. At 250 °C, the peak power density of bi-layer electrolyte fuel cell was ∼ 2 mW/cm2, which is ∼ 56% higher than that of single-layer electrolyte fuel cell due to significant reduction of cathodic activation loss. A set of materials characterizations revealed that the differences in compositions and micro-structures at the electrolytes accounts for the improved performance. - Highlights: • Bi-layer thin-film electrolyte was fabricated with pulsed laser deposition method. • Electrochemical performance was investigated at 250 °C. • The porous layer at the cathode surface improved oxygen reduction reaction. • Compositional and structural properties were examined with ex situ characterizations

  12. Evaporated VOx Thin Films

    Science.gov (United States)

    Stapinski, Tomasz; Leja, E.

    1989-03-01

    VOx thin films on glass were obtained by thermal evaporation of V205, powder. The structural investigations were carried out with the use of X-ray diffractometer. The electrical properties of the film were examined by means of temperature measurements of resistivity for the samples heat-treated in various conditions. Optical transmission and reflection spectra of VOX films of various composition showed the influence of the heat treatment.

  13. A Low Temperature, Solution-Processed Poly(4-vinylphenol), YO(x) Nanoparticle Composite/Polysilazane Bi-Layer Gate Insulator for ZnO Thin Film Transistor.

    Science.gov (United States)

    Shin, Hyeonwoo; Kang, Chan-Mo; Chae, Hyunsik; Kim, Hyun-Gwan; Baek, Kyu-Ha; Choi, Hyoung Jin; Park, Man-Young; Do, Lee-Mi; Lee, Changhee

    2016-03-01

    Low temperature, solution-processed metal oxide thin film transistors (MEOTFTs) have been widely investigated for application in low-cost, transparent, and flexible electronics. To enlarge the application area, solution-processed gate insulators (GI) have been investigated in recent years. We investigated the effects of the organic/inorganic bi-layer GI to ZnO thin film transistors (TFTs). PVP, YO(x) nanoparticle composite, and polysilazane bi-layer showed low leakage current (-10(-8) A/cm2 in 2 MV), which are applicable in low temperature processed MEOTFTs. Polysilazane was used as an interlayer between ZnO and PVP, YO(x) nanoparticle composite as a good charge transport interface with ZnO. By applying the PVP, YO(x), nanoparticle composite/polysilazane bi-layer structure to ZnO TFTs, we successfully suppressed the off current (I(off)) to -10(-11) and fabricated good MEOTFTs in 180 degrees C. PMID:27455680

  14. X-ray photoemission study of CoFeB/MgO thin film bi-layers

    OpenAIRE

    Read, J. C.; Mather, P. G.; Buhrman, R.A.

    2007-01-01

    We present results from an X-ray photoemission spectroscopy (XPS) study of CoFeB/MgO bi-layers where we observe process-dependent formation of B, Fe, and Co oxides at the CoFeB/MgO interface due to oxidation of CoFeB during MgO deposition. Vacuum annealing reduces the Co and Fe oxides but further incorporates B into the MgO forming a composite MgBxOy layer. Inserting an Mg layer between CoFeB and MgO introduces an oxygen sink, providing increased control over B content in the barrier.

  15. Cross-sectional X-ray nano-diffraction and -reflectivity analysis of multilayered AlTiN–TiSiN thin films: Correlation between residual strain and bi-layer period

    International Nuclear Information System (INIS)

    A multi-layered AlTiN–TiSiN thin film with a bi-layer period of ∼6 nm is characterized by cross-sectional synchrotron X-ray nano-diffraction and -reflectivity using an X-ray beam size of 250 × 350 nm2. The complementary approach allows for simultaneous determining gradients of residual strains and bi-layer thickness along the film depth and demonstrates a correlation between them. The observed dependency allows for a residual strain gradient design in multilayered thin films

  16. Characteristic difference between ITO/ZrCu and ITO/Ag bi-layer films as transparent electrodes deposited on PET substrate

    International Nuclear Information System (INIS)

    The metallic-glass film of ZrCu layer deposited by co-sputtering was utilized as the metallic layer in the bi-layer structure transparent conductive electrode of ITO/ZrCu (IZC) deposited on the PET substrate using magnetron sputtering at room temperature. In addition, the pure Ag metal layer was applied in the same structure of transparent conductive film, ITO/Ag, in comparison with the IZC film. The ZrCu layer could form a continuous and smooth film in thickness lower than 6 nm, compared with the island structure of pure Ag layer of the same thickness. The 30 nm ITO/3 nm ZrCu films could show the optical transmittance of 73% at 550 nm wavelength. The 30 nm ITO/12 nm ZrCu films could show the better sheet resistance of 20 Ω/sq, but it was still worse than that of the ITO/Ag films. It was suggested that an alloy system with lower resistivity and negative mixing heat between atoms might be another way to form a continuous layer in thickness lower than 6 nm for metal film.

  17. Characteristic Research on Evaporated Explosive Film

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The evaporation source of evaporated explosive was designed and improved based on the inherent specialties of explosive. The compatibility of explosives and addition agent with evaporation vessels was analyzed. The influence of substrate temperature on explosive was analyzed, the control method of substrate temperature was suggested. The influences of evaporation rate on formation of explosive film and mixed explosive film were confirmed. Optimum evaporation rate for evaporation explosive and the better method for evaporating mixed explosive were presented. The necessary characteristics of the evaporated explosive film were obtained by the research of the differences between the evaporated explosive and other materials.

  18. Thermogravimetric analysis of fuel film evaporation

    Institute of Scientific and Technical Information of China (English)

    HU Zongjie; LI Liguang; YU Shui

    2006-01-01

    Thermogravimetric analysis (TGA) was compared with the petrochemical distillation measurement method to better understand the characteristics of fuel film evaporation at different wall tem- peratures. The film evaporation characteristics of 90# gasoline, 93# gasoline and 0# diesel with different initial thicknesses were investigated at different environmental fluxes and heating rates. The influences of heating rate, film thickness and environmental flux on fuel film evaporation for these fuels were found. The results showed that the environmental conditions in TGA were similar to those for fuel films in the internal combustion engines, so data from TGA were suitable for the analysis of fuel film evaporation. TGA could simulate the key influencing factors for fuel film evaporation and could investigate the basic quantificational effect of heating rate and film thickness. To get a rapid and sufficient fuel film evaporation, sufficiently high wall temperature is necessary. Evaporation time decreases at a high heating rate and thin film thickness, and intense gas flow is important to promoting fuel film evaporation. Data from TGA at a heating rate of 100℃/min are fit to analyze the diesel film evaporation during cold-start and warming-up. Due to the tense molecular interactions, the evaporation sequence could not be strictly divided according to the boiling points of each component for multicomponent dissolved mixture during the quick evaporation process, and the heavier components could vaporize before reaching their boiling points. The 0# diesel film would fully evaporate when the wall temperature is beyond 250℃.

  19. Synthesis of mono- and bi-layer MFI zeolite films on macroporous alumina tubular supports: Application to nanofiltration

    Science.gov (United States)

    Said, Ali; Limousy, Lionel; Nouali, Habiba; Michelin, Laure; Halawani, Jalal; Toufaily, Joumana; Hamieh, Tayssir; Dutournié, Patrick; Daou, T. Jean

    2015-10-01

    This work is dedicated to the development of MFI-type structure zeolite films (single-layer or bilayer) on the internal layer of a specific macroporous alumina tubular support for nanofiltration applications. The bottom MFI layer was obtained by direct hydrothermal synthesis while a secondary growth method was used for the top MFI layer. A complete characterization of the obtained MFI membranes (single-layer or bilayer) is proposed using various techniques, such as X-ray diffraction, scanning electron microscopy, mercury porosimetry and nitrogen sorption measurements. Dense and highly crystallized films of MFI-type structure zeolite were obtained for both single-layer and bilayer MFI films. The total film thickness were around 7.1±0.5 μm and 14.5±1 μm for single-layer and bilayer MFI films respectively. The Si/Al molar ratio of the MFI films varied between 185 and 305 for single-layer and bilayer MFI films respectively. The hydraulic permeability of the tubular MFI membrane was achieved by the filtration of pure water. The hydraulic permeability of the single-layer and bilayer MFI membranes decreased rapidly at the beginning of the conditioning process, and stabilized at 1.08×10-14 m3 m-2 and 1.02×10-15 m3 m-2 after 15 h and the rejection rates of neutral solute (Vb 12) are 10% and 50% for the single-layer and bilayer MFI films respectively.

  20. Powdering characteristics of thin film evaporator, 1

    International Nuclear Information System (INIS)

    Vertical thin film evaporators have been used to concentrate and dry solutions because their rotating swing blades prevent scale from being deposited on the heated surfaces. Powdering capacity of the vertical thin film evaporator was examined experimentally for drying applications of radioactive liquid waste generated from nuclear power plants. As a result, it was found that the powdering capacity increased with the blade rotation, changing significantly in the low ratational region and scarcely in the high rotational region. The powdering capacity in the high rotational region was restricted by the lack of heat flux which was theoretically evaluated for the concentrating process. As the critical factor in the low rotational region was not clear, a visual test apparatus was made to observe flow patterns in the evaporator, and a powdering model was obtained. This model showed that powdering process was obstructed when the liquid film lost its fluidity at high concentration. Based on this model, the powdering process was simulated theoretically with good agreement between calculated and experimental results. (author)

  1. Twisted bi-layer graphene: microscopic rainbows

    OpenAIRE

    Campos-Delgado, J.; Algara-Siller, G.; Santos, C. N.; Kaiser, U.; Raskin, J.-P.

    2013-01-01

    Twisted bi-layer graphene (tBLG) has recently attracted interest due to the peculiar electrical properties that arise from its random rotational configurations. Our experiments on CVD-grown graphene from Cu foil and transferred onto Si substrates, with an oxide layer of 100 nm, reveal naturally-produced bi-layer graphene patches which present different colorations when shined with white light. In particular yellow-, pink- and blue- colored areas are evidenced. Combining optical microscopy, Ra...

  2. Evaporation of Sunscreen Films: How the UV Protection Properties Change.

    Science.gov (United States)

    Binks, Bernard P; Brown, Jonathan; Fletcher, Paul D I; Johnson, Andrew J; Marinopoulos, Ioannis; Crowther, Jonathan M; Thompson, Michael A

    2016-06-01

    We have investigated the evaporation of thin sunscreen films and how the light absorption and the derived sun protection factor (SPF) change. For films consisting of solutions of common UV filters in propylene glycol (PG) as solvent, we show how evaporation generally causes three effects. First, the film area can decrease by dewetting leading to a transient increase in the average film thickness. Second, the film thins by evaporative loss of the solvent. Third, precipitation of the UV filter occurs when solvent loss causes the solubility limit to be reached. These evaporation-induced changes cause the UV absorbance of the film to decrease with resultant loss of SPF over the time scale of the evaporation. We derive an approximate model which accounts semiquantitatively for the variation of SPF with evaporation. Experimental results for solutions of different UV filters on quartz, different skin mimicking substrates, films with added nanoparticles, films with an added polymer and films with fast-evaporating decane as solvent (instead of slow evaporating PG) are discussed and compared with model calculations. Addition of either nanoparticles or polymer suppress film dewetting. Overall, it is hoped that the understanding gained about the mechanisms whereby film evaporation affects the SPF will provide useful guidance for the formulation of more effective sunscreens. PMID:27167054

  3. Separation Efficiency of Thin-film Evaporators

    Institute of Scientific and Technical Information of China (English)

    R.Billet

    2004-01-01

    The recovery of contaminants and useful substances from liquid wastes, the purification of production effluents and the separation of thermally instable mixtures are some of the multivarious applications of thin-film distillors in many processes of the chemical and allied industries and of the food industries. In a study carried out in pilot plants with distillation test systems there was found a good agreement between the experimental separation results and those obtained by computing with a theorectical model; the latter is based on the assumption of phase equilibrium between the vapour formed on an infinitely small element of area in a liquid film of any given concentric periphery of the vertically arranged evaporator. These tests were perfomed under various phase loads.

  4. Falling film evaporators: organic solvent regeneration in nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    The aim of this work was to improve knowledge about working of falling film evaporators used in nuclear fuel reprocessing plants for organic solvent regeneration. The first part deals with a non evaporation film. An original film thickness measuring technique was used; infrared thermography. It gave indications on hydrodynamics and wave amplitude and pointed out thermocapillary forces to be the cause of bad wetting of the heated wall. By another way we showed that a small slit spacing on the film distributor, an enhanced surface roughness and an important liquid flow rate favour a better wetting. The second part deals with evaporation of a binary solvent mixture. Experiments in an industrial evaporator corroborated the fact that it is essential for the efficiency of the apparatus to work at high flow rates. We propose an over-simple model which can be used to estimate performances of co-current falling film evaporators of the process

  5. AMORPHOUS Fe-POLYETHYLENE Co-EVAPORATED FILMS

    OpenAIRE

    Maro, Tsuyoshi; Kitakami, Osamu; Fujiwara, Hideo

    1988-01-01

    Fe-polyethylene films were prepared by simultaneous evaporation of Fe and polyethylene. It was found that these films become amorphous and exhibit softmagnetism. The minimum coercivity in these films was 2 Oe and the saturation magnetization with the minimum coercivity was 1368 G.

  6. Film evaporation MEMS thruster array for micropropulsion

    Science.gov (United States)

    Cofer, Anthony G.

    Current small sat propulsion systems require a substantial mass fraction of the vehicle involving tradeoffs between useful payload mass and maneuverability. This is also an issue with available attitude control systems which are either quickly saturated reaction wheels or movable high drag surfaces with long response times. What is needed is a low mass low power self-contained propulsion unit that can be easily installed and modeled. The proposed Film-Evaporation MEMS Tunable Array (FEMTA), exploits the small scale surface tension effect in conjunction with temperature dependent vapor pressure to realize a thermal valving system. The local vapor pressure is increased by resistive film heating until it exceeds meniscus strength in the nozzle inducing vacuum boiling which provides a stagnation pressure equal to vapor pressure at that point which is used for propulsion. The heat of vaporization is drawn from the bulk fluid and is replaced by either an integrated heater or waste heat from the vehicle. Proof of concept was initially achieved with a macroscale device made possible by using ethylene glycol, which has a low vapor pressure and high surface tension, as the working fluid. Both the thermal valving effect and cooling feature were demonstrated though at reduced performance than would be expected for water. Three generations of prototype FEMTA devices have been fabricated at Birck Nanotechnology Center on 200 and 500 micrometer thick silicon wafers. Preliminary testing on first generation models had tenuously demonstrated behavior consistent with the macroscale tests but there was not enough data for solid confirmation. Some reliability issues had arisen with the integrated heaters which were only partially alleviated in the second generation of FEMTAs. This led to a third generation and two changes in heater material until a chemically resilient material was found. The third generation of microthrusters were tested on the microNewton thrust stand at Purdue

  7. Dewetting of evaporating thin films over nanometer-scale topographies

    Science.gov (United States)

    Akbarzadeh, A. M.; Moosavi, A.; Moghimi Kheirabadi, A.

    2014-07-01

    A lubrication model is used to study dewetting of an evaporating thin film layer over a solid substrate with a nanometer-scale topography. The effects of the geometry of the topography, the contact angle, the film thickness, and the slippage on the dewetting have been studied. Our results reveal that the evaporation enhances the dewetting process and reduces the depinning time over the topography. Also it is shown that the depinning time is inversely proportional to the slippage and increasing the contact angle may considerably reduce the depinning time, while the film thickness increases the depinning time.

  8. Interfacial Evaporation of Falling Liquid Films with Wall Heating

    Institute of Scientific and Technical Information of China (English)

    张金涛; 王补宣; 彭晓峰

    2001-01-01

    The interfacial evaporation of falling water films with wall heating was experimentally studied andanalyzed. The results presented in this paper showed that the capillary-induced interfacial evaporation playedan important role in heat transfer of a falling liquid film. It would be independent of the wall heat flux andsomewhat lower than that without wall heating for impure fluids such as water-air system. The thermodynamicanalysis conducted gave a theoretical basis for the experimental observations. The effective capillary radiuswas correlated with the mass flow rate. The experimental results and analysis showed that the interfacialevaporation should be taken into account in the study of falling liquid film heat transfer.``

  9. Structural characterization of vacuum evaporated ZnSe thin films

    Indian Academy of Sciences (India)

    Pradip Kr Kalita; B K Sarma; H L Das

    2000-08-01

    Thermally evaporated ZnSe thin films deposited on glass substrates within substrate temperatures (s) at 303 K–623 K are of polycrystalline nature having f.c.c. zincblende structure. The most preferential orientation is along [111] direction for all deposited films together with other abundant planes [220] and [311]. The lattice parameter, grain size, average internal stress, microstrain, dislocation density and degree of preferred orientation in the film are calculated and correlated with s.

  10. Effect of nanofluids on thin film evaporation in microchannels

    International Nuclear Information System (INIS)

    A thin film evaporation model based on the augmented Young–Laplace equation and kinetic theories was developed to describe the nanofluid effects on the extended evaporating meniscus in a microchannel. The nanofluid effects include the structural disjoining pressure, a thin porous coating layer at the surface formed by the nanoparticle deposition and the thermophysical property variations compared with the base fluid. The results show that the nanofluid thermal conductivity enhancement mainly due to the Brownian motion tends to greatly increase the liquid film thickness and the thin film heat transfer. The structural disjoining pressure effect tends to enhance the nanofluid spreading capability and the thin film evaporation. The nanoparticle-deposited porous coating layer improves the surface wettability while significantly reducing the thin film evaporation with increasing layer thickness due to the thermal resistance across this layer. The nanofluid thermal conductivity enhancement together with the structural disjoining pressure effect can not counteract the thermal resistance effects of the porous coating layer when the coating layer thickness is sufficiently large.

  11. CeO{sub 2} thin films by flash evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Duverger, A. [CIFUS, Universidad de Sonora, Sonora (Mexico); Rabdel Ruiz-Salvador, A. [Zeolites Engineering Lab., Fac. Physics-IMRE, Univ. de La Habana, Habana (Cuba); Hernandez-Sanchez, M.P. [DIEES, Fac. Physics-IMRE, Universidad de La Habana, Habana (Cuba); Garcia-Sanchez, M.F.; Rodriguez-Gattorno, G. [Lab. Sensors, IMRE, Univ. de La Habana, Habana (Cuba)

    1997-03-27

    Oxide ion conductors have received special attention during the last 20 years for their applications in high temperature fuel cells and sensors. Cerium oxide based solid electrolytes have one of the lowest activation energies among the fluorite type oxide ion conductors. We present a methodology for obtaining cerium oxide thin films by flash evaporation. The films were characterized using X-ray diffraction, optical absorption, and AC conductivity. The results show the ionic nature of the electrical conductivity

  12. Stability of vertical films of molten glass due to evaporation

    OpenAIRE

    Pigeonneau, Franck; Kocarkova, Helena; Rouyer, Florence

    2012-01-01

    First, we report observations achieved on a gravitationally-driven film drainage with molten glass pointing out a stabilizing effect when temperature is larger than 1250 C. A model to describe the change of surface tension with the film thickness due to the evaporation of oxide species is proposed. A lubrication model is derived taking into account the gradient of surface tension. The final system of equations describing the mass and the momentum conservations is numerically solved by an impl...

  13. Thin-liquid-film evaporation at contact line

    Institute of Scientific and Technical Information of China (English)

    Hao WANG; Zhenai PAN; Zhao CHEN

    2009-01-01

    When a liquid wets a solid wall, the extended meniscus near the contact line may be divided into three regions: a nonevaporating region, where the liquid is adsorbed on the wall; a transition region or thin-film region, where effects of long-range molecular forces (disjoining pressure) are felt; and an intrinsic meniscus region, where capillary forces dominate. The thin liquid film, with thickness from nanometers up to micrometers, covering the transition region and part of intrinsic meniscus, is gaining interest due to its high heat transfer rates. In this paper, a review was made of the researches on thin-liquid-film evaporation. The major characteristics of thin film, thin-film modeling based on continuum theory, simulations based on molecular dynamics, and thin-film profile and temperature measurements were summarized.

  14. Anisotropic Magnetoresistance of Cobalt Films Prepared by Thermal Evaporation

    Directory of Open Access Journals (Sweden)

    Yuttanun PANSONG

    2005-01-01

    Full Text Available Cobalt films on silicon substrates were prepared by thermal evaporation. By evaporating 0.05 g of cobalt for 80-240 s, a thickness from 21.1 to 67.7 nm was obtained with a deposition rate about 0.26-0.32 nm per second. The 29 nm-thick cobalt film exhibited magnetoresistance (MR ranging from -0.0793% (field perpendicular to the current to +0.0134% (field parallel to the current with saturation in a 220 mT magnetic field. This MR was attributed to anisotropic magnetoresistance (AMR since changing the angle between the field and the current (θ gave rise to a change in the electrical resistance (Rθ. The results agreed with the theory since the plot between Rθ and cos2θ could be linearly fitted. AMR was not observed in non-ferromagnetic gold films whose resistance was insensitive to the angle between the current and magnetic field.

  15. Influence of Marangoni instability on evaporation of the polar liquid film

    Science.gov (United States)

    Gordeeva, Varvara Y.; Lyushnin, Andrey V.

    2013-03-01

    A thin film of an evaporating polar liquid on a solid substrate is investigated within the framework of the lubrication theory. Using linear analysis, we have found that stability of the film depends only on two control parameters: the evaporation and Maranagoni numbers. We demonstrate that the Marangoni effect plays a destabilizing role while evaporation stabilizes the film.

  16. Adhesion between polymers and evaporated gold and nickel films

    Science.gov (United States)

    Yamada, Y.; Wheeler, D. R.; Buckley, D. H.

    1984-01-01

    To obtain information on the adhesion between metal films and polymeric solids, the adhesion force was measured by means of a tensile pull test. It was found that the adhesion strengths between polymeric solids and gold films evaporated on polymer substrates were (1.11 + or - 0.53) multiplied by 10(6) N/M(2) on PTFE, about 5.49 multiplied by 10(6) N/m(2) on UHMWPE, and 6.54x10(6) on 6/6 nylon. The adhesion strengths for nickel films evaporated on PTFE, UHMWPE, and 6/6 nylon were found to be a factor of 1.7 higher than those for the gold coated PTFE, UHMWPE, and 6/6 nylon. To confirm quantitatively the effect of electron irradiation on the adhesion strength between a PTFE solid and metal films, a tensile pull test was performed on the irradiated PTFE specimens, which were prepared by evaporating nickel or gold on PTFE surfaces irradiated by 2-keV electrons for various times. After irradiation, the adhesion strength increased to (4.92 + or - 0.92)x10(6) N/m(2) for nickel coated PTFE and (1.82 + or - 0.48)x10(6) N/m(2) for gold coated PTFE. The improvement in adhesion for nickel is higher than that for gold.

  17. Experimental and theoretical investigations of falling film evaporation

    Science.gov (United States)

    Pehlivan, Hüseyin; Özdemir, Mustafa

    2012-06-01

    In this study, a mathematical model was developed for falling film evaporation in vacuum using heat transfer relations. An experimental device was designed. experimental set-up which was used was equipped with a triangular weir distribution device and it had the ability to record data up to 3 m. Experiments were performed in a single-effect process with sucrose-water solution varying from 3 to 20% concentration rate of sucrose and we used a vertical tube evaporator with the dimensions of laboratory scale. The model that was developed considers convection, shear stress, viscosity and conjugate heat transfer while most of the previous works ignored these factors. The main factors influencing the heat transfer mechanism performance of the unit were investigated and analyzed. We concluded that the experimental studies are verified by the developed model. Furthermore, it was also concluded that, the heat transfer is affected by the mass flow rate, sucrose concentration rate in solution, film thickness and pressure.

  18. Optical properties of thermally evaporated cadmium telluride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khairnar, U.P.; Bhavsar, D.S.; Vaidya, R.U.; Bhavsar, G.P

    2003-05-26

    Polycrystalline CdTe films have been deposited onto glass substrates at 373 K by vacuum evaporation technique. The transmittance and reflectance have been measured at normal and near normal incidence, respectively, in the spectral range 200-2500 nm. The dependence of absorption coefficient, {alpha} on the photon energy have been determined. Analysis of the result showed that for CdTe films of different thicknesses, direct transition occurs with band gap energies in the range 1.45-1.52 eV. Refractive indices and extinction coefficients have been evaluated in the above spectral range. The XRD analysis confirmed that CdTe films are polycrystalline having hexagonal structure. The lattice parameters of thin films are almost matching with the JCPDS 82-0474 data for cadmium telluride.

  19. Modeling constrained sintering of bi-layered tubular structures

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Kothanda Ramachandran, Dhavanesan; Ni, De Wei; Esposito, Vincenzo; Teocoli, Francesca; Olevsky, Eugene A.; Bjørk, Rasmus; Pryds, Nini; Kaiser, Andreas; Frandsen, Henrik Lund

    2015-01-01

    densification and stress developments during sintering of tubular bi-layered samples. The correspondence between linear elastic and linear viscous theories is used as a basis for derivation of the model. The developed model is first verified by finite element simulation for sintering of tubular bi-layer system...... thermo-mechanical analysis. Results from the analytical model are found to agree well with finite element simulations as well as measurements from sintering experiment....

  20. Multicaloric effect in bi-layer multiferroic composites

    Science.gov (United States)

    Vopson, M. M.; Zhou, D.; Caruntu, G.

    2015-11-01

    The multicaloric effect was theoretically proposed in 2012 and, despite numerous follow up studies, the effect still awaits experimental confirmation. The main limitation is the fact that the multicaloric effect is only observed at a temperature equal to the transition temperature of the magnetic and electric phases coexisting within a multiferroic (MF) (i.e., T ≈ Tcm ≈ Tce). Such condition is hard to fulfill in single phase MFs and a solution is to develop suitable composite MF materials. Here, we examine the multicaloric effect in a bi-layer laminated composite MF in order to determine the optimal design parameters for best caloric response. We show that magnetically induced multicaloric effect requires magnetic component of heat capacity smaller than that of the electric phase, while the layer thickness of the magnetic phase must be at least 5 times the thickness of the electric phase. The electrically induced multicaloric effect requires the magnetic layer to be 10% of the electric phase thickness, while its heat capacity must be larger than that of the electric phase. These selection rules are generally applicable to bulk as well as thin film MF composites for optimal multicaloric effect.

  1. Multicaloric effect in bi-layer multiferroic composites

    Energy Technology Data Exchange (ETDEWEB)

    Vopson, M. M., E-mail: melvin.vopson@port.ac.uk [Faculty of Science, University of Portsmouth, Portsmouth PO1 3QL (United Kingdom); Zhou, D. [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Caruntu, G. [Department of Chemistry and Biochemistry, Central Michigan University, Mount Pleasant, Michigan 48858 (United States)

    2015-11-02

    The multicaloric effect was theoretically proposed in 2012 and, despite numerous follow up studies, the effect still awaits experimental confirmation. The main limitation is the fact that the multicaloric effect is only observed at a temperature equal to the transition temperature of the magnetic and electric phases coexisting within a multiferroic (MF) (i.e., T ≈ T{sub c}{sup m} ≈ T{sub c}{sup e}). Such condition is hard to fulfill in single phase MFs and a solution is to develop suitable composite MF materials. Here, we examine the multicaloric effect in a bi-layer laminated composite MF in order to determine the optimal design parameters for best caloric response. We show that magnetically induced multicaloric effect requires magnetic component of heat capacity smaller than that of the electric phase, while the layer thickness of the magnetic phase must be at least 5 times the thickness of the electric phase. The electrically induced multicaloric effect requires the magnetic layer to be 10% of the electric phase thickness, while its heat capacity must be larger than that of the electric phase. These selection rules are generally applicable to bulk as well as thin film MF composites for optimal multicaloric effect.

  2. PREPARATION AND PROPERTIES OF Ni-Cr AND Fe-Cr-Al FILMS BY VACUUM EVAPORATION

    Institute of Scientific and Technical Information of China (English)

    X. W. Shi; Z.Y. Liu; D.C. Zeng; C.M. Li

    2003-01-01

    Ni-Cr and Fe-Cr-Al films deposited on the Al2O3 substrate are studied by a method of vacuum evaporation in this paper. Influence of resistance value on density and evaporation parameters of the films reveals that the resistance of films and the adhesion of films to substrates are determined by the evaporation time and the substrate temperate under the condition of the maximum vacuity of 6.2×10-4 pa, respectively.

  3. Refrigerant falling film evaporation review: Description, fluid dynamics and heat transfer

    International Nuclear Information System (INIS)

    Falling film horizontal tube evaporators for refrigeration equipment are an interesting alternative to pool boiling evaporators concerning operation costs, safety, thermodynamic efficiency, charge of refrigerant or size. Plenty of literature works studied falling film evaporation, but for its application in fields such as desalination and petrochemical industry or OTEC. This review focuses mainly on those works from the literature that analysed the main issues of falling film evaporation of refrigerants, to better understand heat transfer and fluid dynamics in such evaporators. First, falling film evaporation is described and compared to pool boiling, to define its main advantages and inconveniences. Then, the literature concerning film around the tubes and between them is analysed, as well as the phenomenon of film breakdown, which sharply deteriorates the heat transfer performance of falling film evaporators. After it, the results from those works that studied analytically and experimentally the heat transfer coefficients (HTCs) with different types of tubes and refrigerants are discussed. The review finishes with a brief summary of important parameters of falling film evaporation, which might be useful for the design of such equipment. - Highlights: •We defined falling film evaporation and compared it with pool boiling. •We reviewed works from the literature concerning refrigerant falling film evaporation. •We classified the ideas from the works attending to crucial aspects of the process. •We developed a summary of the main ideas which could be useful for design purpose

  4. Photoconductivity in reactively evaporated copper indium selenide thin films

    International Nuclear Information System (INIS)

    Copper indium selenide thin films of composition CuInSe2 with thickness of the order of 130 nm are deposited on glass substrate at a temperature of 423 ±5 K and pressure of 10−5 mbar using reactive evaporation, a variant of Gunther's three temperature method with high purity Copper (99.999%), Indium (99.999%) and Selenium (99.99%) as the elemental starting materials. X-ray diffraction (XRD) studies shows that the films are polycrystalline in nature having preferred orientation of grains along the (112) plane. The structural type of the film is found to be tetragonal with particle size of the order of 32 nm. The structural parameters such as lattice constant, particle size, dislocation density, number of crystallites per unit area and strain in the film are also evaluated. The surface morphology of CuInSe2 films are studied using 2D and 3D atomic force microscopy to estimate the grain size and surface roughness respectively. Analysis of the absorption spectrum of the film recorded using UV-Vis-NIR Spectrophotometer in the wavelength range from 2500 nm to cutoff revealed that the film possess a direct allowed transition with a band gap of 1.05 eV and a high value of absorption coefficient (α) of 106 cm−1 at 570 nm. Photoconductivity at room temperature is measured after illuminating the film with an FSH lamp (82 V, 300 W). Optical absorption studies in conjunction with the good photoconductivity of the prepared p-type CuInSe2 thin films indicate its suitability in photovoltaic applications

  5. Asymmetric co-evaporated Co-Cr films: magnetic parameters and reversal mechanism

    NARCIS (Netherlands)

    Kranenburg, van Herma; Lodder, Cock; Popma, Theo J.A.

    1993-01-01

    The magnetic parameters of co-evaporated Co-Cr films, where Cr was deposited obliquely, are investigated. Process-induced compositional separation enhanced the energy product. When the substrate was rotated during evaporation, the perpendicular characteristics were lost.

  6. Bitumen immobilization of aqueous radwaste by thin-film evaporation

    International Nuclear Information System (INIS)

    In the early 1980s, AECL built a Waste Treatment Centre (WTC) for managing low-level solid and aqueous liquid wastes for converting CANDU wastes. At present, two liquid waste streams are being treated at the WTC. The liquid waste streams are volume-reduced by a combination of continuous crossflow microfiltration (MF), spiral wound reverse osmosis (SWRO) and tubular reverse osmosis (TRO) membrane technologies. The concentrate produced from the TRO system and the volume-reduced MF backwash solutions are evaporated while simultaneously adding bitumen in a thin-film evaporator. A water-free product of chemical and radiochemical salts and bitumen is removed in 200-L galvanized steel drums for storage. The radiation field of product drums on contact typically has a value of 0.5 to 3 R/h depending upon the feed concentration of radioactivity to the evaporator. The total solids content in the 200-L drum ranges from 25 to 35%. Encapsulated in the bitumen matrix are a variety of nonradiochemical salts, which comprise the bulk of the total solids that are in the product drum. This report discusses the immobilization of the aqueous waste with bitumen in a thin-film evaporator. Simulated bituminized waste forms were leached in accordance with the ANS/ANSI 16.1 leach test. In this test, the waste form is immersed under water for an extended period of time, and the leachate is periodically removed and chemically analysed. The Leachability index varied between 7 and 9 for the emulsified bitumen waste forms produced at the WTC. Bitumen samples were unconfined and subjected to immersion and frequent leachate replenishment. The results of leach tests will be a lower bound for the performance of the bitumen waste product in an unsaturated environment. The Leachability indexes reported exceeds the USNRC minimum requirement for wasteform criteria. Adding protective overcoats of either Portland cement or oxidized bitumen enhanced the Leachability index. 8 refs., 3 tabs., 6 figs

  7. Evaporators

    DEFF Research Database (Denmark)

    Knudsen, Hans Jørgen Høgaard

    1996-01-01

    Type of evaporators. Regulation. Thermal dimensioning. Determination of pressure loss and heat transfer coefficients.......Type of evaporators. Regulation. Thermal dimensioning. Determination of pressure loss and heat transfer coefficients....

  8. Experimental study of falling film evaporation in large scale rectangular channel

    International Nuclear Information System (INIS)

    Highlights: • This paper studies the falling film evaporation in large scale rectangular channel experimentally. • The effects of air flow rate, film temperature and film flow rate on falling film evaporation are analyzed. • Increasing the air flow rate is considered as an efficient method to enhance the evaporation rate. • A correlation including the wave effect for falling film evaporation is derived based on heat and mass transfer analogy. - Abstract: The falling film evaporation in a large scale rectangular channel is experimentally studied in this paper for the design and improvement of passive containment cooling system. The evaporation mass transfer coefficient hD is obtained by the evaporation rate and vapor partial pressure difference of film surface and air bulk. The experimental results indicate that increasing of air flow rate appears to enhance hD, while the film temperature and film flow rate have little effect on hD. Since the wave effect on evaporation is noticed in experiment, the evaporation mass transfer correlation including the wave effect is developed on the basis of heat and mass transfer analogy and experimental data

  9. Studies on Thin Films of Antimony Vacuum Evaporated from a Knudsen-Type Source

    Directory of Open Access Journals (Sweden)

    K.L. Chaudhary

    2000-10-01

    Full Text Available A Knudsen-type evaporation source was used for the deposition of thin films of antimony to study their growth and microstructure under different rates of evaporation and substrate temperatures when vacuum evaporated onto air-cleaved KC1, mica, amorphous carbon and doped KCl substrates. The crystallisation of these films on exposure to an electron beam of moderate intensity inside the electron microscope was studied, and the orientations of the crystallised films wrt the substrate were established. It has been concluded that antimony films prepared by this source compare well with those prepared by other sources of vacuum evaporation.

  10. Optical characteristics of poly(tetrafluoroethylene) thin film prepared by a vacuum evaporation

    Science.gov (United States)

    Ohnishi, Yasutaka; Kita, Rio; Tsuchiya, Kazuyoshi; Iwamori, Satoru

    2016-02-01

    Poly(tetrafluoroethylene) (PTFE) thin films were deposited onto a glass slide substrate by a heat-resistance type vacuum evaporation apparatus due to changing the evaporation conditions. Transparency of the PTFE thin films prepared by the vacuum evaporation depended on the deposition conditions, i.e., temperatures of the basket, and distance between the evaporation source and substrate. To elucidate relationship between the molecular structure and transparency of the PTFE thin film prepared by the vacuum evaporation, chemical structures, crystallinity and thermophysical property were investigated. The chemical bonding state of the PTFE thin film prepared by the vacuum evaporation was almost the same as that of the pristine PTFE, however, the crystalinity was different. Although the pristine PTFE was crystal structure, the transparent evaporated thin film was estimated to be microcrystal structure. In addition, endothermic peaks in a differential scanning calorimeter (DSC) spectrum of the PTFE thin film were different from that of the pristine PTFE. These endothermic peaks of the PTFE thin film prepared by the vacuum evaporation shifted lower temperature compared to the pristine PTFE, which suggests that molecular weight of the PTFE thin film prepared by the vacuum evaporation decreased compared with that of the pristine PTFE.

  11. Bubble-assisted film evaporation correlation for saline water at sub-atmospheric pressures in horizontal-tube evaporator

    KAUST Repository

    Shahzad, Muhammad Wakil

    2013-01-01

    In falling film evaporators, the overall heat transfer coefficient is controlled by film thickness, velocity, liquid properties and the temperature differential across the film layer. This article presents the heat transfer behavior for evaporative film boiling on horizontal tubes, but working at low pressures of 0.93-3.60 kPa (corresponding solution saturation temperatures of 279-300 K) as well as seawater salinity of 15,000 to 90,000 mg/l or ppm. Owing to a dearth of literature on film-boiling at these conditions, the article is motivated by the importance of evaporative film boiling in the desalination processes such as the multi-effect distillation (MED) or multi-stage flashing (MSF): It is observed that in addition to the above-mentioned parameters, evaporative heat transfer of seawater is affected by the emergence of micro-bubbles within the thin film layer, particularly when the liquid saturation temperatures drop below 298 K (3.1 kPa). Such micro bubbles are generated near to the tube wall surfaces and they enhanced the heat transfer by two or more folds when compared with the predictions of conventional evaporative film boiling. The appearance of micro-bubbles is attributed to the rapid increase in the specific volume of vapor, i.e., dv/dT, at low saturation temperature conditions. A new correlation is thus proposed in this article and it shows good agreement to the measured data with an experimental uncertainty of 8% and regression RMSE of 3.5%. © 2012 Elsevier Ltd. All rights reserved.

  12. Percolation structure observed in evaporated Nd-Fe-B films

    International Nuclear Information System (INIS)

    This paper reports on thin alloy films prepared by evaporating a standard magnetic Nd2Fe14B ingot in a high vacuum e-gun system at room temperature. The as deposited films of 50 nm thick were characterized by transmission electron microscopy (TEM) and in-situ energy dispersive spectroscopy (EDS). Bright field examination showed that a novel morphology with holes or varied sizes emerged in the films. The hole-like white areas enriched with Nd, and the dark network with Fe. The electron micrograph was digitized by an VAX image processor. An infinite cluster was proved to be a two-dimensional percolating structure at the percolation threshold. The fractal dimension and the percolation threshold were calculated to be 1.90 ± 0.04 and 0.60 ± 0.04, respectively, which are in good consonance with the theoretical predictions. The as-deposited samples were aged at room temperature for about two months. Enhanced diffusion and solid state reaction induced another percolating networks composed essentially by Fe7Nd and Nd-riched solid solution

  13. Experimental Investigation of Heat Transfer Coefficient in Vertical Tube Rising Film Evaporator

    OpenAIRE

    Syed Naveed Ul Hasan; Sultan Ali

    2011-01-01

    This paper reports the experimental evaluation of the heat transfer coefficient (U) in a VRF (Vertical Tube Rising Film Evaporator). The aim is to describe the variation of U against different process parameters. Experiments were carried out for laminar flow conditions. The experimental unit is a floor standing tubular framework for a rising film evaporation system. There are many parameters affecting heat transfer coefficient in evaporators, but it was not possible to consider all of them, s...

  14. Heat transfer and visualization of falling film evaporation on a tube bundle

    International Nuclear Information System (INIS)

    Horizontal falling film evaporators have the potential of displacing flooded evaporators in industry, due to advantages such as lower required refrigerant charge and lower pressure drop. However, there is a need to improve the understanding of falling film evaporation mechanisms to provide accurate thermal design methods. In this work, the existing LTCM falling film facility was utilized to perform falling film evaporation measurements on a single tube, a vertical row of horizontal tubes and a small tube bundle. Two enhanced boiling tubes, namely the Wolverine Turbo-B5 and the Wieland Gewa-B5, were tested using R-134a and R-236fa. The tests were carried out at a constant saturation temperature of Tsat = 5 °C, liquid film Reynolds numbers ranging from 0 to 3000, and heat fluxes between 15 and 90 kW/m2 in pool boiling and falling film configurations. A visualization study was performed under adiabatic and diabatic conditions (in both single-array and bundle configurations) to study the flow. The physical phenomena governing the falling film evaporation process have been studied, and insight into their effects on the performance of tube bundles has been gained. Measurements of the local heat transfer coefficient were obtained and utilized to generate new prediction methods, including a method for predicting the onset-of-dryout film flow rate during falling film evaporation, local pool boiling and falling film heat transfer prediction methods and a falling film multiplier prediction method. (author)

  15. Optical studies on electron beam evaporated Lithium Triborate films

    Science.gov (United States)

    Mohandoss, R.; Dhanuskodi, S.; Sanjeeviraja, C.

    2012-10-01

    Lithium triborate (LB3) has numerous applications in scintillator for neutron detection, laser weapon and communication. LB3 films have been prepared by electron beam evaporation technique under a pressure of 1 × 10-5 mbar on glass substrate at 323 K for 4 min. The crystallographic orientations and the lattice parameters (a = 8.55 (2); b = 5.09 (2); c = 7.39 (2) Å) were determined by powder XRD indicating the (1 1 1) preferential orientation of the film. The lower cut off wavelength at 325 nm with 75% transparency was measured from the UV-vis spectrum. The optical constants extinction coefficient (K), reflectance (R), the linear refractive index (1.34) and the optical energy band gap (˜4.0 eV) were estimated. The photoluminescence spectrum shows the emission peak in the visible region with low concentration of oxygen defects. LB3 is found to be second harmonic generation (SHG) active using a Q-switched Nd:YAG laser (1064 nm, 9 ns, 10 Hz). The nonlinear refractive index (n2 ˜ 10-16 cm2/W) and nonlinear absorption coefficient (β ˜ 10-2 cm/W) reveal (Z-scan technique) that the material has negative nonlinearity and self-focusing nature.

  16. Electron diffraction studies on CVD grown bi-layered graphene

    Science.gov (United States)

    Lingam, Kiran; Karakaya, Mehmet; Podila, Ramakrishna; Quin, Haijun; Rao, Apparao; Dept. of Physics and Astronomy, Clemson University, Clemson, SC USA 29634. Team; Advanced Materials Research Laboratories, Clemson University, Anderson, SC USA 29625 Collaboration

    2013-03-01

    Graphene has generated enormous interest in the scientific community due to its peculiar properties like electron mobility, thermal conductivity etc. Several recent reports on exfoliated graphene emphasized the role of layer stacking on the electronic and optical properties of graphene in case of bi-layered and few layered graphene and several synthesis techniques like chemical vapor deposition (CVD) on Copper foils are employed to prepare graphene for applications at a large scale. However, a correlated study pertinent to the stacking order in CVD grown graphene is still unclear. In this work, using a combination of Raman spectroscopy and selected area electron diffraction analysis we analyzed the preferred misorientation angles in a CVD grown bi-layered graphene and also the role of Cu crystal facets on the graphene stacking order will be presented.

  17. STM-induced light emission from vacuum-evaporated gold film

    Indian Academy of Sciences (India)

    J U Ahamed; S Katano; Y Uehara

    2015-09-01

    A vacuum evaporation system has been used to evaporate gold film on glass substrate in order to probe the scanning tunneling microscope-light emission (STM-LE) from the evaporated film. The surface morphology of the evaporated Au film has been checked by atomic force microscope (AFM). In order to estimate the appropriate thickness of the Au film, which is essential for the enhancement of STM-LE in the prism-coupled geometry, a theoretical calculation has been performed. Our theoretical simulation revealed that the light emission from the prism-coupled STM junction is strongly enhanced when the Au film has a thickness of 40 nm. AFM observation also showed that the morphology of the gold films strongly depends on the cleanliness of glass substrates and the deposition temperature. Relatively smooth surface was observed when a 40-nm-thick Au film was evaporated at room temperature on the preannealed glass substrate. Finally, the evaporated films were deposited on the flat bottom of a hemispherical glass prism, and STM-LE from the tip–sample gap into the vacuum (tip-side emission) and into the prism (prism-side emission) were measured. It was found from the experimental results that the prism-side emission is much stronger than the tip-side emission by virtue of the enhancement of the prism-coupled geometry.

  18. Thin Film Mediated Phase Change Phenomena: Crystallization, Evaporation and Wetting

    Science.gov (United States)

    Wettlaufer, John S.

    1998-01-01

    We focus on two distinct materials science problems that arise in two distinct microgravity environments: In space and within the space of a polymeric network. In the former environment, we consider a near eutectic alloy film in contact with its vapor which, when evaporating on earth, will experience compositionally induced buoyancy driven convection. The latter will significantly influence the morphology of the crystallized end member. In the absence of gravity, the morphology will be dominated by molecular diffusion and Marangoni driven viscous flow, and we study these phenomena theoretically and experimentally. The second microgravity environment exists in liquids, gels, and other soft materials where the small mass of individual molecules makes the effect of gravity negligible next to the relatively strong forces of intermolecular collisions. In such materials, an essential question concerns how to relate the molecular dynamics to the bulk rheological behavior. Here, we observe experimentally the diffusive motion of a single molecule in a single polymer filament, embedded within a polymer network and find anomalous diffusive behavior.

  19. Chloroform micro-evaporation induced ordered structures of poly(L-lactide) thin films

    DEFF Research Database (Denmark)

    Huang, Shaoyong; Li, Hongfei; Shang, Yingrui; Yu, Donghong; Li, Gao; Jiang, Shichun; Chen, Xuesi; An, Lijia

    2013-01-01

    Self-assembly of poly(L-lactide) (PLLA) in thin films induced by chloroform micro-evaporation was investigated by microscopic techniques and X-ray diffraction studies. A film-thickness dependent on highly ordered structures has been derived from disordered films. Ring-banded spherulitic and...

  20. Influence of organic films on the evaporation and condensation of water in aerosol

    OpenAIRE

    Davies, James F.; Miles, Rachael E H; Haddrell, Allen E; Reid, Jonathan P.

    2013-01-01

    Uncertainties in quantifying the kinetics of evaporation and condensation of water fromatmospheric aerosol are a significant contributor to the uncertainty in predicting cloud droplet number and the indirect effect of aerosols on climate. The influence of aerosol particle surface composition, particularly the impact of surface active organic films, on the condensation and evaporation coefficients remains ambiguous. Here, we report measurements of the influence of organic films on the evaporat...

  1. Heat and mass transfer in binary film evaporation and condensation in vertical channel

    OpenAIRE

    Abdelaziz Nasr; Abdulmajeed S. Al-Ghamdi

    2015-01-01

    Evaporation and condensation in the presence of binary liquid film flowing on one of two parallel vertical plates by mixed convection have been studied numerically. The first plate is adiabatic and wetted by a binary liquid film while the second one is dry and isothermal. The results concern the effects of the inlet parameters on the ethylene glycol evaporation and on the water condensation. Results obtained show that the increase of the inlet vapor concentration of water benefits its condens...

  2. Evaporation suppression from spent fuel storage and disassembly basins with monolayer films

    International Nuclear Information System (INIS)

    Spent fuel storage and disassembly basins at non-commercial heavy water reactor facilities contain significant quantities of tritiated water. The use of monolayer films for suppressing evaporation from spent nuclear fuel storage basins was investigated. Octadecanol spread easily over large surfaces with a newly designed film pump. This system reduced the evaporation rate by 50%. Consequently, personnel radiation exposure due to tritiated water vapor can be significantly reduced

  3. Desertification of the Peritoneum by Thin-Film Evaporation During Laparoscopy

    OpenAIRE

    Ott, Douglas E.

    2003-01-01

    Objective: To assess the effects of gas flow during insufflation on peritoneal fluid and peritoneal tissue regarding transient thermal behavior and thin-film evaporation. The effects of laparoscopic gas on peritoneal cell desiccation and peritoneal fluid thin-film evaporation were analyzed. Methods: Measurment of tissue and peritoneal fluid and analysis of gas flow dynamics during laparoscopy. Results: High-velocity gas interface conditions during laparoscopic gas insufflation result in perit...

  4. Investigation of the evaporation process conditions on the optical constants of zirconia films

    International Nuclear Information System (INIS)

    Deposition parameters required for producing zirconia films for use in optical multilayer systems by electron-beam gun evaporation of zirconia and zirconium starting materials were investigated. The optical constants were determined as a function of distance, partial pressure of oxygen, and angle of incidence. The direct and reactive evaporation processes yielded ZrO2 films with refractive indices of 2.08 and 2.14, respectively, for vapor incident on the substrate at normal incidence

  5. Growth of thin fullerene films by Matrix Assisted Pulsed Laser Evaporation

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster, Søren

    bound carbon molecule with a well-defined mass (M = 720 amu) and therefore a good, organic test molecule. C60 fullerene thin films of average thickness of more than 100 nm was produced in vacuum by matrix-assisted pulsed laser evaporation (MAPLE). A 355 nm Nd:YAG laser was di-rected onto a frozen target...... favours evaporation of matrix and organic molecules, resulting in production of films with smooth surfaces and minimal contamination....

  6. Role of evaporation time on the structural and optical properties of ZnO films deposited by thermal evaporator

    Science.gov (United States)

    Khan, Ijaz Ahmad; Noor, Mamoona; Rehman, Aatiqa; Farid, Amjad; Shahid, M. Attique Khan; Shafiq, M.

    2015-12-01

    Zinc oxide films are deposited on Si substrates by thermal evaporator for different evaporation times (ET). XRD pattern shows the development of different diffraction peaks related to Zn, ZnO and Zn2SiO4 phases which confirms the deposition of composite film. The orientation transformation is observed with increasing ET. The maximum peak intensity of ZnO (1 0 1) plane is observed at 3 h ET. The dislocation density observed in ZnO (1 0 1) plane varies from 1.53 × 10-3 nm-2 to 8.94 × 10-3 nm-2. The lattice parameters of ZnO are found to be a = 3.243 Å and c = 5.197 Å. FTIR analysis confirms the formation of ZnO films. SEM microstructures exhibit the formation nano-wires, nano-bars, nano-strips and nano-needles. The optical energy band gap of ZnO films deposited for various ET varies from 3.98 eV to 4.06 eV. Results show that the peak intensity of ZnO (1 0 1) plane, orientation transformation and the presence of Si content are responsible to increase the energy band gap of ZnO films.

  7. Performance of a solar energy powered falling film evaporator with film promoter

    International Nuclear Information System (INIS)

    A solar energy powered falling film evaporator with film promoter was developed for concentrating diluted solutions (industrial effluents). The procedure proposed here does not emit CO2, making it a viable alternative to the method of concentrating solutions that uses vapor as a heat source and releases CO2 from burning fuel oil in a furnace, in direct opposition to the carbon reduction agreement established by the Kyoto protocol. This novel device consists of the following components: a flat plate solar collector with adjustable inclination, a film promoter (adhering to the collector), a liquid distributor, a concentrate collector, and accessories. The evaporation rate of the device was found to be affected both by the inclination of the collector and by the feed flow. The meteorological variables cannot be controlled, but were monitored constantly to ascertain the behavior of the equipment in response to the variations occurring throughout the day. Higher efficiencies were attained when the inclination of the collector was adjusted monthly, showing up to 36.4% higher values than when the collector remained in a fixed position

  8. Characterisation of CdO thin films deposited by activated reactive evaporation

    Science.gov (United States)

    Ramakrishna Reddy, K. T.; Sravani, C.; Miles, R. W.

    1998-02-01

    The paper describes the preparation of cadmium oxide thin films produced by "activated reactive evaporation" onto heated glass substrates. The structural, electrical and optical properties of the deposited films were investigated and the effect of substrate temperature on the different physical properties of the films investigated. Highly conducting, polycrystalline CdO films with good transmittances were prepared by controlling the deposition temperature. These layers can be used to produce CdO/CdTe solar cells with efficiencies > 7%.

  9. Studies on tin oxide films prepared by electron beam evaporation and spray pyrolysis methods

    Indian Academy of Sciences (India)

    K S Shamala; L C S Murthy; K Narasimha Rao

    2004-06-01

    Transparent conducting tin oxide thin films have been prepared by electron beam evaporation and spray pyrolysis methods. Structural, optical and electrical properties were studied under different preparation conditions like substrate temperature, solution flow rate and rate of deposition. Resistivity of undoped evaporated films varied from 2.65 × 10-2 -cm to 3.57 × 10-3 -cm in the temperature range 150–200°C. For undoped spray pyrolyzed films, the resistivity was observed to be in the range 1.2 × 10-1 to 1.69 × 10-2 -cm in the temperature range 250–370°C. Hall effect measurements indicated that the mobility as well as carrier concentration of evaporated films were greater than that of spray deposited films. The lowest resistivity for antimony doped tin oxide film was found to be 7.74 × 10-4 -cm, which was deposited at 350°C with 0.26 g of SbCl3 and 4 g of SnCl4 (SbCl3/SnCl4 = 0.065). Evaporated films were found to be amorphous in the temperature range up to 200°C, whereas spray pyrolyzed films prepared at substrate temperature of 300–370°C were polycrystalline. The morphology of tin oxide films was studied using SEM.

  10. Experimental and numerical analysis for optimal design parameters of a falling film evaporator

    Indian Academy of Sciences (India)

    RAJNEESH KAUSHAL; RAJ KUMAR; GAURAV VATS

    2016-06-01

    Present study exhibits an experimental examination of mass transfer coefficient and evaporative effectiveness of a falling film evaporator. Further, a statistical replica is extended in order to have optimal controlling parameters viz. non-dimensional enthalpy potential, film Reynolds number of cooling water, Reynolds number of air and relative humidity of up-streaming air. The models not only give an optimal solution but also help in establishing a correlation among controlling parameters. In this context, response surface methodology is employed by aid of design of experiment approach. Later, the response surface curves are studied using ANOVA. Finally, the relations established are confirmed experimentally to validate the models. The relations thus established are beneficent in furtherance of designing evaporators. Additionally, the presentstudy is among the first attempts to reveal the effect of humidity on the performance of falling film evaporator.

  11. Vibration analysis of bi-layered FGM cylindrical shells

    Energy Technology Data Exchange (ETDEWEB)

    Arshad, Shahid Hussain; Sultana, Nazra; Iqbal, Zafar [University of Sargodha, Department of Mathematics, Sargodha, Punjab (Pakistan); Naeem, Muhammad Nawaz [G C University Faisalabad, Department of Mathematics, Faisalabad, Punjab (Pakistan); Shah, Abdul Ghafar [The Islamia University of Bahawalpur, Department of Mathematics, Bahawalpur, Punjab (Pakistan)

    2011-03-15

    In the present study, a vibration frequency analysis of a bi-layered cylindrical shell composed of two independent functionally graded layers is presented. The thickness of the shell layers is assumed to be equal and constant. Material properties of the constituents of bi-layered functionally graded cylindrical shell are assumed to vary smoothly and continuously through the thickness of the layers of the shell and are controlled by volume fraction power law distribution. The expressions for strain-displacement and curvature-displacement relationships are utilized from Love's first approximation linear thin shell theory. The versatile Rayleigh-Ritz approach is employed to formulate the frequency equations in the form of eigenvalue problem. Influence of material distribution in the two functionally graded layers of the cylindrical shells is investigated on shell natural frequencies for various shell parameters with simply supported end conditions. To check the validity, accuracy and efficiency of the present methodology, results obtained are compared with those available in the literature. (orig.)

  12. Thin film evaporation in mixed convection along an inclined plane surface; Evaporation en convection mixte d`un film mince s`ecoulant sur une surface plane inclinee

    Energy Technology Data Exchange (ETDEWEB)

    Agunaoun, A.; Daif, A.; Daguenet, M. [Universite de Perpignan, 66 (France); Kaoua, M. [Ecole Normale Superieure, Marrakech (Morocco)

    1996-06-01

    Thin film evaporation and evaluation of drying front pose numerous theoretical problems and present a great practical interest, especially in turbine blades cooling during fuel injection. The present works concerns a steady state, laminar, established and one way water flow in thin film on an inclined plane surface which is isothermal or subject to uniform heat flux. It is assumed that above the liquid free surface, there exists a steady state laminar flow of humid air parallel to the surface in the same direction or in the opposite direction of the water thin film. (A.B.)

  13. Investigation of annular flow at high evaporation rates in view of liquid film cooling

    Science.gov (United States)

    Nahstoll, Juergen

    1988-01-01

    The process of liquid film cooling of combustion chamber walls which are subjected to extremely high heat rates was investigated. A theoretical model was developed for a reliable prediction of the film cooling length. The mass transfer at the liquid-gas interface results from evaporated liquid and entrained liquid droplets. The film cooling length analysis, which includes the physical effects in detail, is separated into two regions: heating the liquid and evaporating the liquid. The theoretical results were experimentally verified at high pressures and temperatures using a modified H2/O2-rocket motor. There is a good agreement between the theoretical and the experimental results over the experimental range.

  14. Effects of Sulfurization Temperature on Properties of CZTS Films by Vacuum Evaporation and Sulfurization Method

    OpenAIRE

    Jie Zhang; Bo Long; Shuying Cheng; Weibo Zhang

    2013-01-01

    Copper zinc tin sulfur (CZTS) thin films have been extensively studied in recent years for their advantages of low cost, high absorption coefficient (≥104 cm−1), appropriate band gap (~1.5 eV), and nontoxicity. CZTS thin films are promising materials of solar cells like copper indium gallium selenide (CIGS). In this work, CZTS thin films were prepared on glass substrates by vacuum evaporation and sulfurization method. Sn/Cu/ZnS (CZT) precursors were deposited by thermal evaporation and then s...

  15. Surface structure and composition of flat titanium thin films as a function of film thickness and evaporation rate

    International Nuclear Information System (INIS)

    To correlate flat titanium film surface properties with deposition parameters, titanium flat thin films were systematically deposited on glass substrates with various thicknesses and evaporation rates by electron-beam evaporation. The chemical compositions, crystal structure, surface topographies as well as wettability were investigated by using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and water contact angle measurement, respectively. The films consisted mainly of TiO2. Small percentages of Ti2O3 and metallic Ti were also found at the film surface using high-resolution XPS analysis. Quantitative XPS showed little differences regarding elemental compositions among different groups of films. The films were obtained by varying the deposition rate and the film thickness, respectively. XRD data showed consistent reflection patterns of the different titanium samples deposited using different film thicknesses. Without exception measurements of all samples exhibited contact angles of 80 deg ± 5 deg . Quantitative AFM characterization demonstrated good correlation tendency between surface roughness and film thickness or evaporation rate, respectively. It is important to notice that titanium films with different sizes of grains on their surfaces but having the same chemistry and film bulk structure can be obtained in a controllable way. By increasing the film thickness and evaporation rate, the surface roughness increased. The surface morphology and grain size growth displayed a corresponding trend. Therefore, the control of these parameters allows us to prepare titanium films with desired surface properties in a controllable and reproducible way for further biological investigations of these materials

  16. Falling film evaporation on a tube bundle with plain and enhanced tubes

    International Nuclear Information System (INIS)

    The complexities of two-phase flow and evaporation on a tube bundle present important problems in the design of heat exchangers and the understanding of the physical phenomena taking place. The development of structured surfaces to enhance boiling heat transfer and thus reduce the size of evaporators adds another level of complexity to the modeling of such heat exchangers. Horizontal falling film evaporators have the potential to be widely used in large refrigeration systems and heat pumps, in the petrochemical industry and for sea water desalination units, but there is a need to improve the understanding of falling film evaporation mechanisms to provide accurate thermal design methods. The characterization of the effect of enhanced surfaces on the boiling phenomena occurring in falling film evaporators is thus expected to increase and optimize the performance of a tube bundle. In this work, the existing LTCM falling film facility was modified and instrumented to perform falling film evaporation measurements on single tube row and a small tube bundle. Four types of tubes were tested including: a plain tube, an enhanced condensing tube (Gewa-C+LW) and two enhanced boiling tubes (Turbo-EDE2 and Gewa-B4) to extend the existing database. The current investigation includes results for two refrigerants, R134a and R236fa, at a saturation temperature of Tsat = 5 °C, liquid film Reynolds numbers ranging from 0 to 3000, at heat fluxes between 20 and 60 kW/m² in pool boiling and falling film configurations. Measurements of the local heat transfer coefficient were obtained and utilized to improve the current prediction methods. Finally, the understanding of the physical phenomena governing the falling film evaporation of liquid refrigerants has been improved. Furthermore, a method for predicting the onset of dry patch formation has been developed and a local heat transfer prediction method for falling film evaporation based on a large experimental database has been proposed

  17. Vacuum-evaporated ferroelectric films and heterostructures of vinylidene fluoride/trifluoroethylene copolymer

    International Nuclear Information System (INIS)

    The potential of the vacuum method for preparing ferroelectric films and photonic heterostructures from organic materials is studied. Vacuum-evaporated films of fluoropolymers and heterostructures on their basis are obtained and their ferroelectric and spectral properties are studied. In particular, homogeneous films of the well-known piezoelectric polymer polyvinylidene fluoride and ferroelectric material vinylidene fluoride/trifluoroethylene copolymer (P(VDF/TFE)) are produced. Experimental studies of vacuum-evaporated P(VDF/TFE) films confirmed their ferroelectric properties. The heterostructures composed of alternating layers of P(VDF/TFE) copolymer molecules and azodye molecules are fabricated by vacuum evaporation. Owing to the controlled layer thickness and a significant difference in the refractive indices of the P(VDF/TFE) copolymer and azodyes, these heterostructures exhibit properties of photonic crystals. This finding is confirmed by the occurrence of a photonic band in the absorption spectra of the heterostructures.

  18. Characteristics of deposition process of thin films by ion-beam evaporation

    International Nuclear Information System (INIS)

    Intense pulsed ion-beam evaporation (IBE) has been proposed as one of the new techniques for the preparation of thin films. To understand the basic process of thin film deposition, the energy deposition on the substrate surface by ablation plasma was measured by using calorimetric technique. The characteristics of prepared thin films were studied with deposition energy. In addition, the substrate temperature was calculated, based on the experimental results, by using one-dimensional simulations only considering heat conduction. (author)

  19. Evaporation suppression from spent-fuel storage basins with monolayer films

    International Nuclear Information System (INIS)

    Spent-fuel storage and disassembly basins at noncommercial heavy water reactor facilities contain significant quantities of tritiated water. Since the water temperature is typically above room temperature (i.e., 25 to 35 degrees C), a substantial amount of tritiated water evaporates from these basins. Personnel are normally protected from radiation by limiting the water temperature and the tritium activity levels in the basins. The tritium activity limit is maintained by periodically purging the basins with fresh water. Reducing the evaporation rate of these basins with a monolayer film will reduce the transport rate of Tritiated water into the atmosphere within the basin building. This may allow higher tritium concentration levels in the basin without exceeding the dose limits for operational personnel. Allowing a higher tritium activity level can result in fewer basin purgings. In this study, two facilities were designed for measuring water evaporation in a controlled environment. In the first facility, various surfactant materials, spreading solvents, and film application methods were tested on a 1.2-m-diam water surface. In the second facility, several film application methods for covering a large complex water surface, which measured 3 x 6 m, were tested. For all experiments, the ambient air conditions, water temperature, and evaporation rate were measured under steady-state conditions (similar to those found in spent-fuel storage and disassembly basins) for 24 h. Data were collected to compare the evaporation rate without a film to that with a film present

  20. Inhomogeneity and microstructure in e-beam evaporated ZrO2 films

    International Nuclear Information System (INIS)

    In this paper thin films of zirconium dioxide are deposited by e-beam evaporation on optically polished borosilicate crown glass. Two different oxygen partial pressures in the chamber are used. The optical properties of the films are characterized by ellipsometry. The influence of oxygen stoichiometry on the composition and microstructure of the material is investigated by polycrystalline X-ray diffraction for different film thicknesses. The films are found to be inhomogeneous, and a composition gradient (i.e. amorphous ↔ tetragonal ↔ monoclinic) is observed from the substrate to the surface. The oxygen partial pressure influences the growth of the films

  1. Ge-doped SiO2 thin films produced by helicon activated reactive evaporation

    International Nuclear Information System (INIS)

    Ge-doped SiO2 thin films for optical waveguide application were produced at low temperature by using an improved helicon plasma assisted reactive evaporation technique. Pure Si and Ge materials were simultaneously evaporated from two separated crucibles by using e-beams into high-density oxygen plasma to form the oxide films on a substrate. The film density was enhanced by supplying an r.f. bias to the substrate. Nearly H-free Ge-doped SiO2 thin films with very high atomic density (∼0.66x1023 cm-3), good adhesion and very low surface roughness were produced. The influence of deposition conditions, mainly the helicon r.f. power and substrate bias, on the properties of the films was studied by using surface profilometer, ellipsometer, atomic force microscope, Rutherford backscattering spectrometry, Fourier transform infrared spectrometry, and field emission scanning electron microscope

  2. Finite-time Thin Film Rupture Driven by Generalized Evaporative Loss

    CERN Document Server

    Ji, Hangjie

    2016-01-01

    Rupture is a nonlinear instability resulting in a finite-time singularity as a fluid layer approaches zero thickness at a point. We study the dynamics of rupture in a generalized mathematical model of thin films of viscous fluids with evaporative effects. The governing lubrication model is a fourth-order nonlinear parabolic partial differential equation with a non-conservative loss term due to evaporation. Several different types of finite-time singularities are observed due to balances between evaporation and surface tension or intermolecular forces. Non-self-similar behavior and two classes of self-similar rupture solutions are analyzed and validated against high resolution PDE simulations.

  3. Structural changes of evaporated tantalum during film growth

    International Nuclear Information System (INIS)

    According to the Sondheimer approximation the resistivity of an infinitely thick film with the same structure as a thin film can be determined from the graph of rhod versus d (where rho is the resistivity and d the film thickness). Since the resistivity is highly sensitive to film structure it is possible to observe structural changes by making in situ measurements during film growth. From these measurements it can be established that tantalum films condense under ultrahigh vacuum at room temperature onto oxide substrates (e.g. Corning 7059 glass, sapphire or BeO) as the β phase. It can be demonstrated that the transition temperature from β-Ta to α-Ta decreases with increasing film thickness. Increasing the substrate temperature (e.g. to 3000C) causes the tantalum films to nucleate first as the β phase and to be converted into α-Ta during film growth. This effect is influenced by the substrate. The thickness dependence of the structure of tantalum was confirmed by ultrahigh vacuum in situ annealing experiments and electron optical investigations. (Auth.)

  4. Foam-film-stabilized liquid bridge networks in evaporative lithography and wet granular matter

    KAUST Repository

    Vakarelski, Ivan Uriev

    2013-04-23

    Evaporative lithography using latex particle templates is a novel approach for the self-assembly of suspension-dispersed nanoparticles into ordered microwire networks. The phenomenon that drives the self-assembly process is the propagation of a network of interconnected liquid bridges between the template particles and the underlying substrate. With the aid of video microscopy, we demonstrate that these liquid bridges are in fact the border zone between the underlying substrate and foam films vertical to the substrate, which are formed during the evaporation of the liquid from the suspension. The stability of the foam films and thus the liquid bridge network stability are due to the presence of a small amount of surfactant in the evaporating solution. We show that the same type of foam-film-stabilized liquid bridge network can also propagate in 3D clusters of spherical particles, which has important implications for the understanding of wet granular matter. © 2013 American Chemical Society.

  5. Electrical properties of LiNbO3 (electrolyte)/Cu (anode) bi-layers

    International Nuclear Information System (INIS)

    In this work specific film structures of Li-Nb-O/Li/Li-Nb-O are investigated by AC Impedance Spectroscopy measurements at different temperatures. This gives the opportunity to investigate properties of the material itself and, at the same time, to consider the influence of the grain boundaries on the ionic behavior of the polycrystalline Lithium Niobate. On the other hand, LiNbO3/Li/Cu multi-layers are studied as electrolyte/anode bi-layers and potential parts of 'Li-free' microbatteries. The Li deficiency in the as deposited Li-Nb-O films is cured by forming a 'sandwich' of Li-Nb-O/Li/Li-Nb-O, which after annealing becomes ionic conductor. The electrical behavior of an annealed film depends on two sources. The first is due to properties of the material itself and the second is based on the network of the grain boundaries. The average size of the grains is strongly influenced by the structure of the ohmic-contact/substrate. The electrical behavior of the electrolyte/anode interface of the 'Li-free' structure LiNbO3/Li/Cu/Au is very similar to the impedance measurements of the single LiNbO3 single films. The whole multilayer structure, though, presents a third relaxation time which is consistent of a small resistance. This resistance is independent of temperature and it seems that is due to the metallic interface Li/Cu/Au.

  6. Experimental investigation of convective structure evolution and heat transfer in quasi-steady evaporating liquid films

    Science.gov (United States)

    Kimball, J. T.; Hermanson, J. C.; Allen, J. S.

    2012-05-01

    The stability, convective structure, and heat transfer characteristics of upward-facing, evaporating, thin liquid films were studied experimentally. Dichloromethane, chloroform, methanol, and acetone films with initial thicknesses of 2-5 mm were subjected to constant levels of superheating until film rupture occurred (typically at a thickness of around 50 μm). The films resided on a temperature controlled, polished copper plate incorporated into a closed pressure chamber free of non-condensable gasses. The dynamic film thickness was measured at multiple points using a non-intrusive ultrasound ranging system. Instability wavelength and convective structure information was obtained using double-pass schlieren imaging. The sequence of the convective structures as the film thins due to evaporation is observed to be as follows: (1) large, highly variable cells, (2) concentric rings and spirals, and (3) apparent end of convection. The transition from large, variable cells to concentric rings and spirals occurs at a Rayleigh number of 4800 ± 960. The apparent end of convection occurs at a Rayleigh number of 1580 ± 180. At the cessation of convection, the Nusselt number is nearly unity, indicating that there is little heat transfer in the film due to convection. In films where the Rayleigh number is above this transitional value, the Nusselt number increases with increasing Rayleigh number. The current results suggest that the equilibrium condition at the evaporating surface suppresses surface temperature variation, effectively eliminating thermocapillary-driven instability.

  7. Characterization of hafnium oxide thin films prepared by electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Kuhaili, M F [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Durrani, S M A [Center for Applied Physical Sciences, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Khawaja, E E [Center for Applied Physical Sciences, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2004-04-21

    Thin films of hafnium oxide were deposited by electron beam evaporation. The effects of the substrate temperature and the oxygen partial pressure on the refractive index and carbon monoxide sensing properties of the films were studied. The films were characterized using x-ray diffraction and x-ray photoelectron spectroscopy techniques. Films deposited on unheated substrates were amorphous, whereas those deposited on heated substrates showed a mixture of amorphous and polycrystalline structure. All the films were found to be optically inhomogeneous. The inhomogeneity of the films was taken into account in the determination of their refractive indices. It was found that the porosity (as reflected by the refractive indices) of the films was the main factor that affected the sensitivity of the films in relation to their detection of carbon monoxide.

  8. Characterization of hafnium oxide thin films prepared by electron beam evaporation

    International Nuclear Information System (INIS)

    Thin films of hafnium oxide were deposited by electron beam evaporation. The effects of the substrate temperature and the oxygen partial pressure on the refractive index and carbon monoxide sensing properties of the films were studied. The films were characterized using x-ray diffraction and x-ray photoelectron spectroscopy techniques. Films deposited on unheated substrates were amorphous, whereas those deposited on heated substrates showed a mixture of amorphous and polycrystalline structure. All the films were found to be optically inhomogeneous. The inhomogeneity of the films was taken into account in the determination of their refractive indices. It was found that the porosity (as reflected by the refractive indices) of the films was the main factor that affected the sensitivity of the films in relation to their detection of carbon monoxide

  9. Fabrication of Carbon Nanotube Thin Films by Evaporation-Induced Self-Assembly

    OpenAIRE

    Li, Han

    2015-01-01

    In summary, we have prepared single-wall carbon nanotube (SWNT) thin films by the method of evaporation-induced self-assembly (EISA). Using the scalable two-plate or lens setups, sorts of different film types or patterns of SWNTs has been successfully fabricated directly from the evaporation of solvents and could be precisely controlled by the concentrations of SWNT in ambient conditions. The special geometry of meniscus as the capillary bridge has not only given rise to a much higher efficie...

  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. Matrix Assisted Pulsed Laser Evaporation for growth of fullerene thin films

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster Nielsen, Søren

    C60 fullerene thin films of average thickness of more than 100 nm can be produced in vacuum by matrix-assisted pulsed laser evaporation (MAPLE). A 355 nm Nd:YAG laser was directed onto a frozen target of anisole with a concentration of 0.67 wt% C60. At laser fluences below 1.5 J/cm2, a dominant...... fluences, are caused by ejection of large matrix-fullerene liquid droplets into the gas-phase and subsequent deposition. At similar laser energies, but using an unfocused laser beam, MAPLE favours evaporation of matrix and organic molecules, resulting in production of films with smooth surfaces and minimal...

  12. Growth of thin fullerene films by matrix assisted pulsed laser evaporation

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster, Søren

    C60 fullerene thin films of average thickness of more than 100 nm on silicon substrates can be produced in vacuum by matrix-assisted pulsed laser evaporation (MAPLE). A 355 nm Nd:YAG laser was directed onto a frozen target of anisole with a concentration of 0.67 wt% C60. At laser fluences below 1......, observed over a wide range of laser fluences, are caused by ejection of large matrix-fullerene liquid droplets into the gas-phase and subsequent deposition. At similar laser energies, but using an unfocused laser beam, MAPLE favours evaporation of matrix and organic molecules, resulting in films with...

  13. Spin-pump-induced spin transport in a thermally evaporated pentacene film

    International Nuclear Information System (INIS)

    We report the spin-pump-induced spin transport properties of a pentacene film prepared by thermal evaporation. In a palladium(Pd)/pentacene/Ni80Fe20 tri-layer sample, a pure spin-current is generated in the pentacene layer by the spin-pumping of Ni80Fe20, which is independent of the conductance mismatch problem in spin injection. The spin current is absorbed into the Pd layer, converted into a charge current with the inverse spin-Hall effect in Pd, and detected as an electromotive force. This is clear evidence for the pure spin current at room temperature in pentacene films prepared by thermal evaporation

  14. Influence of solvent evaporation rate on crystallization of poly(vinylidene fluoride) thin films

    Indian Academy of Sciences (India)

    K Pramod; R B Gangineni

    2015-08-01

    The processes for obtaining crystalline and smooth poly(vinylidene fluoride) (PVDF) thin films using 2-butanone solvent are explored. The in-situ substrate temperature has been systematically controlled to observe the crystallization process. The in-situ substrate temperature is manipulated to control the rate of evaporation of 2-butanone solvent and is found to have played a vital role in the crystallization of PVDF thin films. Further, X-ray diffraction and Raman microscope were utilized to understand the crystalline phase of PDVF thin films, while atomic force microscopy and scanning electron microscopy have been utilized to investigate the surface morphology and surface roughness of the films.

  15. Structural and optical characterization of thermally evaporated bismuth and antimony films for photovoltaic applications

    Science.gov (United States)

    Srimathy, N.; Ruban Kumar, A.

    2016-05-01

    In this present study, the thin film of bismuth and antimony is coated by thermal evaporation system equipped with the inbuilt ultra high vacuum system. XRD analysis confirmed the rhombohedral structure of Bismuth and Antimony on the prepared film. The surface roughness and physical appearance is analyzed by Atomic force microscopy. The results of Raman Spectroscopy show the wave functions and the spectrum of electrons. The preparation technique and conditions strongly influence the crystalline structure and the phase composition of bismuth and antimony thin films. The electrical and optical properties for the prepared film are analyzed. The results show a great interest and promising applications in Photovoltaic devices.

  16. Electron beam evaporated LaF3 thin films prepared by different temperatures and deposition rates

    International Nuclear Information System (INIS)

    LaF3 thin films were prepared by electron beam evaporation with different temperatures and deposition rates. Microstructure properties including crystalline structure and surface roughness were investigated by X-ray diffraction (XRD) and optical profilograph. X-ray photoelectron spectroscopy (XPS) was employed to study the chemical composition of the films. Optical properties (transmittance and refractive index) and laser induce damage threshold (LIDT) at 355 nm of the films were also characterized. The effects of deposition rate and substrate temperature on microstructure, optical properties and LIDT of LaF3 thin films were discussed, respectively.

  17. Characterization of ZnO:Si nanocomposite films grown by thermal evaporation

    International Nuclear Information System (INIS)

    Composite films were fabricated by co-evaporating Zinc Oxide with Silicon at room temperatures. The resulting films had polycrystalline grains of Zinc Oxide whose grain size were few hundred nanometers, embedded in the silicon matrix. These nanocrystalline grains of ZnO showed good photoluminescence emission at 520 nm along with a photoluminescence emission at 620 nm being contributed by the silicon background. Thus, the nanocomposite films gave a board emission, making it a potentially useful candidate for optoelectronic devices. The photo-luminescent property of the films was found to be stable since the homgenously dispersed ZnO nanocrystals were not allowed to agglomerate by the silicon background

  18. Electrical and optical properties of vacuum evaporated CdS thin film

    International Nuclear Information System (INIS)

    The thin films of cadmium sulfide, CdS, prepared by vacuum evaporation were studied. The data of electrical and optical properties of the films were made on the as deposited samples as well as the one that have been exposed to IR and air, and subjected to thermal annealing. The IR exposure and thermal annealing produced the Cd riched films such as shown by the electrical and optical characteristics of the samples. The experiments show that the films experienced a major ageing process during the first week of air exposure. The band-gap, E sub g=2.44 eV of Cds produced by vacuum evaporation technique in the experiment is suitable for solar cell fabrication

  19. Preparation and Characterization of Thermally Evaporated Octa Substituted Zinc Phthalocyanine Thin Films

    Directory of Open Access Journals (Sweden)

    Vinu T. Vadakel

    2012-12-01

    Full Text Available Thin films of Zinc Octakis Octyloxy Phthalocyanine (ZnPcOC8 are prepared at a base pressure of 10 – 5 Torr using Hind Hi-Vac-12A4 thermal evaporation plant. The films are deposited onto precleaned glass substrates kept at room temperature. Absorption spectra of the films are recorded using the Shimadzu 160A UV-Visible spectrophotometer. The effect of post deposition annealing on the optical constants are studied. The nature of optical transition is found to be direct type. The optical band gap energy of the annealed samples remains almost the same. The invariance of the optical band gap shows the thermal stability of the material for optical applications. The X-ray diffraction analysis of vacuum evaporated films reveals that the crystallinity increases with increase in annealing temperature. The variation of the surface morphology with annealing is also studied using Scanning Electron Micrograph (SEM.

  20. Gadolinium scandate thin films as an alternative gate dielectric prepared by electron beam evaporation

    OpenAIRE

    Wagner, M.; Heeg, T.; Schubert, J.; Lenk, S.; Mantl, S.; Zhao, C; Caymax, M.; De Gendt, M. A.

    2006-01-01

    Gadolinium scandate thin films deposited on silicon substrates using electron beam evaporation were investigated. Measurements with Rutherford backscattering spectrometry, high temperature x-ray diffraction, x-ray reflectometry, transmission electron microscopy, and atomic force microscopy were performed. A stoichiometric transfer of material from the source to the substrate in high vacuum could be demonstrated. Homogeneous, amorphous, and smooth films (root mean square surface roughness < 1 ...

  1. Numerical study of heat and mass transfer during evaporation of a thin liquid film

    Directory of Open Access Journals (Sweden)

    Oubella M’hand

    2015-01-01

    Full Text Available A numerical study of mixed convection heat and mass transfer with film evaporation in a vertical channel is developed. The emphasis is focused on the effects of vaporization of three different liquid films having widely different properties, along the isothermal and wetted walls on the heat and mass transfer rates in the channel. The induced laminar downward flow is a mixture of blowing dry air and vapour of water, methanol or acetone, assumed as ideal gases. A two-dimensional steady state and elliptical flow model, connected with variable thermo-physical properties, is used and the phase change problem is based on thin liquid film assumptions. The governing equations of the model are solved by a finite volume method and the velocity-pressure fields are linked by SIMPLE algorithm. The numerical results, including the velocity, temperature and concentration profiles, as well as axial variations of Nusselt numbers, Sherwood number and dimensionless film evaporation rate are presented for two values of inlet temperature and Reynolds number. It was found that lower the inlet temperature and Re, the higher the induced flows cooling with respect of most volatile film. The better mass transfer rates related with film evaporation are found for a system with low mass diffusion coefficient.

  2. Polycrystalline GaSb thin films grown by co-evaporation

    Institute of Scientific and Technical Information of China (English)

    Qiao Zaixiang; Sun Yun; He Weiyu; He Qing; Li Changjian

    2009-01-01

    We report optical and electrical properties of polycrystalline GaSb thin films which were successfully grown by co-evaporation on soda-lime glass substrates. The thin films have preferential orientation of the (111)direction. SEM results indicate that the average grain size of GaSb thin film is 500 nm with the substrate temperature of 560 ℃. The average reflectance of GaSb thin film is about 30% and the absorption coefficient is of the order of 104 cm-1. The optical bandgap of GaSb thin film is 0.726 eV. The hole concentration shows a clear increasing trend as the Ga-evaporation-temperature/Sb-evaporation-temperature (TGa/TSb) ratio increases. When the Ga crucible temperature is 810 ℃ and the antinomy crucible temperature is 415 ℃, the hole concentration of polycrystalline GaSb is 2 x 1017 cm-3 and the hole mobility is 130 cm2/(V-s). These results suggest that polycrystalline GaSb thin film is a good candidate for the use as a cheap material in TPV cells.

  3. Performance of a wiped-film evaporator with simulated high level waste slurries

    International Nuclear Information System (INIS)

    The evaporation of simulated nuclear fuel reprocessing high level wastes was studied with a 5 ft.$sup 2$, horizontal wiped-film evaporator. The heat transfer and operating characteristics of the evaporator and the properties of the concentrated products were observed for several simulated high level and intermediate level waste slurries. Overall heat transfer coefficients ranging from 150 to 350 Btu/(hr.)(ft.$sup 2$)($degree$F) were observed, depending on the evaporator feed rate and the feed composition. For high level waste compositions the limiting product concentration appeared to be about 50% solids by weight. At this concentration the product flowed readily while hot, but would stiffen if cooled. Scaling of the heat-transfer surfaces became excessive in this range of product concentration. 2 refs

  4. The effect of interfacial evaporation on heat and mass transfer of falling liquid film

    Institute of Scientific and Technical Information of China (English)

    王补宣; 张金涛; 彭晓峰

    2001-01-01

    Analysis of experimental data and estimation of the order of magnitude for interfacial mass diffusion have demonstrated that considerable excess evaporation exists on the free interface of falling liquid film, and that the capillary pressure caused by surface tension is the driving force of this excess interfacial evaporation, which we called the “capillarity-induced interfacial evaporation”. By correlating the experimental data, an empirical expression of the effective capillary radius, r\\-e, is obtained with which the evaporative rate formula we derived and reported previously has been modified to improve the prediction of the critical heat flux for film breakdown. Comparisons with the available predicting models show that our modified equation can predict the experimental results with much lower relative deviation.

  5. Processing of C60 thin films by Matrix-Assisted Pulsed Laser Evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster, Søren

    2011-01-01

    Thin films of fullerenes (C60) were deposited onto silicon using matrix-assisted pulsed laser evaporation (MAPLE). The deposition was carried out from a frozen homogeneous dilute solution of C60 in anisole (0.67 wt%), and over a broad range of laser fluences, from 0.15 J/cm2 up to 3.9 J/cm2. MAPL...

  6. Effects of Sulfurization Temperature on Properties of CZTS Films by Vacuum Evaporation and Sulfurization Method

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    2013-01-01

    Full Text Available Copper zinc tin sulfur (CZTS thin films have been extensively studied in recent years for their advantages of low cost, high absorption coefficient (≥104 cm−1, appropriate band gap (~1.5 eV, and nontoxicity. CZTS thin films are promising materials of solar cells like copper indium gallium selenide (CIGS. In this work, CZTS thin films were prepared on glass substrates by vacuum evaporation and sulfurization method. Sn/Cu/ZnS (CZT precursors were deposited by thermal evaporation and then sulfurized in N2 + H2S atmosphere at temperatures of 360–560°C to produce polycrystalline CZTS thin films. It is found that there are some impurity phases in the thin films with the sulfurization temperature less than 500°C, and the crystallite size of CZTS is quite small. With the further increase of the sulfurization temperature, the obtained thin films exhibit preferred (112 orientation with larger crystallite size and higher density. When the sulfurization temperature is 500°C, the band gap energy, resistivity, carrier concentration, and mobility of the CZTS thin films are 1.49 eV, 9.37 Ω · cm, 1.714×1017 cm−3, and 3.89 cm2/(V · s, respectively. Therefore, the prepared CZTS thin films are suitable for absorbers of solar cells.

  7. Structural and electrical characteristics of the thermally evaporated InSb thin films

    International Nuclear Information System (INIS)

    Polycrystalline InSb thin films have been prepared by the two-source thermal co-evaporation method. The InSb films have been grown on both pure Si (100 substrate and on Si (100) substrate which has been thermally oxidized to form a thin amorphous SiOx overlayer. The as-grown films have been heat treated under N2 atmosphere at different temperatures ranged from 520 to 535 C. Both as-grown films have (22) diffraction as the main peak. The heat treated films which have high mobility values show the (111) preferred orientation. For the heat treated film on oxidized Si substrate, the TEM cross sectional morphologies show the existence of the precipitation of the second phase and the interface diffusion of InSb into the SiOx layer

  8. BI-LAYER HYBRID BIOCOMPOSITES: CHEMICAL RESISTANT AND PHYSICAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Mohammad Jawaid,

    2012-02-01

    Full Text Available Bi-layer hybrid biocomposites were fabricated by hand lay-up technique by reinforcing oil palm empty fruit bunch (EFB and jute fibre mats with epoxy matrix. Hybrid composites were prepared by varying the relative weight fraction of the two fibres. The physical (void content, density, dimensional stability, and chemical resistant properties of hybrid composites were evaluated. When the jute fibre loading increased in hybrid composites, physical and chemical resistant properties of hybrid composites were enhanced. Void content of hybrid composites decreased with an increase in jute fibre loading because jute fibres showed better fibre/matrix interface bonding, which leads to a reduction in voids. The density of hybrid composite increased as the quantity of jute fibre loading increased. The hybridization of the jute fibres with EFB composite improved the dimensional stability of the hybrid composites. The performance of hybrid composites towards chemical reagents improved with an increase in jute fibre loading as compared to the EFB composite. The combination of oil palm EFB/jute fibres with epoxy matrix produced hybrid biocomposites material that is competitive to synthetic composites.

  9. The effect of interfacial evaporation on heat and mass transfer of falling liquid film

    Institute of Scientific and Technical Information of China (English)

    WANG; Buxuan; (

    2001-01-01

    [1]Wasden, F.K., Dukler, A.E., Insight into the hydrodynamics of free falling wavy films, AIChE J., 1989, 35(2): 187.[2]Jayanti, S., Hewitt, G.F., Hydrodynamics and heat transfer of wavy thin film flow, Int. J. Heat Mass Transfer, 1997, 40(10): 179.[3]Seban, R.A., Faghri, A., Evaporation and heating with turbulent falling liquid films, ASME J. Heat Transfer, 1976, 98C: 315.[4]Yang, W.M., Evaporation cooling of liquid film in turbulent mixed convection channel flows, Int. J. Heat Mass Transfer, 1998, 41(23): 3719.[5]Wang, B.X., Zhang, J.T., Peng, X.F., Experimental study on the dryout heat flux of falling liquid film, accepted by Int. J. Heat Mass Transfer as HMT# 2507.[6]Udell, K.S., Heat transfer in porous media heated from above with evaporation, condensation, and capillary effects, ASME J. Heat Transfer, 1983, 105: 485.[7]Carey, V.P., Liquid-Vapor Phase-Change Phenomena——An Introduction to the Thermophysics of Vaporization and Conduction Processes in Heat Transfer Equipment, Washington: Hemisphere Publishing Corporation, 1992, 112.[8]Eames, I.W., Marr, N.J., Sabir, H., The evaporation coefficient of water: a review, Int. J. Heat Mass Transfer, 1997, 40(12): 2963.[9]Israelachvili, J.N., Intermolecular and Surface Forces, San Diego: Academic Press, 1990, 16-30.[10]Holman, J.P., Heat Transfer, 5th ed., Tokyo: McGraw-Hill, Inc, 1981.[11]Zhang, J.T., Wang, B.X., Peng, X.F., Falling liquid film thickness measurement by optical-electronic method, Rev. Scientific Instruments, 2000, 71(4): [12]Zhang, J.T., Wang, B.X., Peng, X.F., Investigation on the interfacial evaporation of falling liquid film with wall heating, accepted by J. Tsinghua University.[13]Fujita, T., Ueda, T., Heat transfer to falling liquid films and film breakdown, Int. J. Heat Mass Transfer, 1978, 21: 97.[14]Bohn, M.S., Davis, S.H., Thermocapillary breakdown of falling liquid films at high Reynolds numbers, Int. J. Heat Masss Transfer, 1993, 36

  10. Effect of He+ irradiation on the optical properties of vacuum evaporated silver indium selenide thin films

    International Nuclear Information System (INIS)

    We prepared polycrystalline silver indium selenide thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The samples were subjected to the irradiation of 1.26 M eV He+ ion. The effect of irradiation on the optical properties has been investigated for different fluencies of He+. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. It is observed that the band gap of silver indium selenide thin films decreases gradually from 1.17 to 0.82 eV with ion fluency.

  11. Low temperature deposition of indium tin oxide films by plasma ion-assisted evaporation.

    Science.gov (United States)

    Füchsel, Kevin; Schulz, Ulrike; Kaiser, Norbert; Tünnermann, Andreas

    2008-05-01

    Coatings of transparent conductive oxides, especially indium tin oxide (ITO), are important in different fields. So far, application of these materials has been limited to substrates with high thermal stability. We describe an improved coating process for ITO based on plasma ion-assisted evaporation at a substrate temperature below 100 degrees C, which is suitable for organic substrates. In characterizing the thin films, we used the classical Drude theory to calculate the resistivity from optical film properties and compared the data with linear four-point measurements. X-ray diffraction spectroscopy was used to determine the structural properties of the thin films. PMID:18449263

  12. A Stochastic Model of Particle Deposition and Evaporation for Ionic Self-Assembly of Thin Films

    International Nuclear Information System (INIS)

    We investigate nanoparticle self-assembly using a stochastic model based on cooperative sequential adsorption with evaporation mechanisms and aimed specifically at the creation of optical thin films. Applying the mean field approximation, we derive a rate equation for particle density. We solve directly for the particle density in both the steady state and time-dependent cases. The analytical results are compared to Monte Carlo simulations of the self-assembly process and to experimental data for self-assembled thin films. We relate our theoretical model to the final particle density for thin films created under varied nanoparticle suspension concentrations

  13. Electrical, structural, and chemical properties of HfO₂ films formed by electron beam evaporation

    OpenAIRE

    Cherkaoui, K.; Monaghan, S.; Negara, M. A.; Modreanu, M.; Hurley, P. K.; O’Connell, D.; McDonnell, Stephen; Hughes, Greg; Wright, S.; Barklie, R.C.; Bailey, P; Noakes, T. C. Q.

    2008-01-01

    High dielectric constant hafnium oxide films were formed by electron beam (e-beam) evaporation on HF last terminated silicon (100) wafers. We report on the influence of low energy argon plasma ( ∼ 70 eV) and oxygen flow rate on the electrical, chemical, and structural properties of metal-insulator-silicon structures incorporating these e-beam deposited HfO2 films. The use of the film-densifying low energy argon plasma during the deposition results in an increase in the equivalent oxide thickn...

  14. Thin film solar cells made of sputtered and evaporated amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, W.; Ruebel, H.; Iselborn, S.; Arenas, G.; Wagner, C.; Schroeder, B.; Geiger, J.

    1984-01-01

    In this paper we report on the results of a study about the fundamental properties of sputtered and evaporated a-Si:H as well as about the application of this material for the preparation of solar cells. Correlations have been found between the photoelectrical properties of the films and the amount and bonding configuration of the hydrogen incorporated both influencing the film structure. Optimum passivated sputtered material, which contains about 10 at% hydrogen has been deposited for preparation of Schottky and p-i-n type solar cells. In first tests conversion efficiencies eta larger than 2% have been measured. A possible conversion efficiency of eta=13.5 mA x 0.7 V x 0.54/100 mW=5% can be calculated taking the best values which were obtained for the parameters of numerous cells prepared till now. Great progress has been made in the defect passivation of reactively evaporated a-Si:H films.

  15. An improved film evaporation correlation for saline water at sub-atmospheric pressures

    KAUST Repository

    Shahzada, Muhammad Wakil

    2011-10-03

    This paper presents an investigation of heat transfer correlation in a falling-film evaporator working with saline water at sub-atmospheric pressures. The experiments are conducted at different salinity levels ranging from 15000 to 90000 ppm, and the pressures were maintained between 0.92 to 2.81 kPa (corresponds to saturation temperatures of 5.9 – 23 0C). The effect of salinity, saturation pressures and chilled water temperatures on the heat transfer coefficient are accounted in the modified film evaporation correlations. The results are fitted to the Han & Fletcher\\'s and Chun & Seban\\'s falling-film correlations which are used in desalination industry. We modify the said correlations by adding salinity and saturation temperature corrections with respective indices to give a better agreement to our measured data.

  16. Thin-Film Evaporative Cooling for Side-Pumped Laser

    Science.gov (United States)

    Stewart, Brian K. (Inventor)

    2010-01-01

    A system and method are provided for cooling a crystal rod of a side-pumped laser. A transparent housing receives the crystal rod therethrough so that an annular gap is defined between the housing and the radial surface of the crystal rod. A fluid coolant is injected into the annular gap such the annular gap is partially filled with the fluid coolant while the radial surface of the crystal rod is wetted as a thin film all along the axial length thereof.

  17. Unoccupied electronic structure and molecular orientation of rubrene; from evaporated films to single crystals

    Science.gov (United States)

    Ueba, T.; Park, J.; Terawaki, R.; Watanabe, Y.; Yamada, T.; Munakata, T.

    2016-07-01

    Two-photon photoemission (2PPE) spectroscopy and ultraviolet photoemission spectroscopy (UPS) have been performed for rubrene single crystals and evaporated thin films on highly oriented pyrolytic graphite (HOPG). The changes in the 2PPE intensity from the single crystals by the polarization of the light and by the angle of the light incident plane against the crystalline axes indicate that the molecular arrangement on the surface is similar to that in the bulk crystal. On the other hand, in the case of evaporated films, the polarization dependence of 2PPE indicates that the tetracene backbone becomes standing upright as the thickness increases. In spite of the alignment of molecules, the broadened 2PPE spectral features for thick films suggest that the films are amorphous and molecules are in largely different environments. The film structures are confirmed by scanning tunneling microscopy (STM). The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) derived levels of the single crystal are shifted by + 0.18 and - 0.20 eV, respectively, from those of the 0.8 ML film. The shifts are attributed to the packing density of molecules. It is shown that the unoccupied electronic structure is more sensitively affected by the film structure than the occupied electronic structure.

  18. Physical properties of vacuum evaporated CdTe thin films with post-deposition thermal annealing

    Science.gov (United States)

    Chander, Subhash; Dhaka, M. S.

    2015-09-01

    This paper presents the physical properties of vacuum evaporated CdTe thin films with post-deposition thermal annealing. The thin films of thickness 500 nm were grown on glass and indium tin oxide (ITO) coated glass substrates employing thermal vacuum evaporation technique followed by post-deposition thermal annealing at temperature 450 °C. These films were subjected to the X-ray diffraction (XRD),UV-Vis spectrophotometer, source meter and atomic force microscopy (AFM) for structural, optical, electrical and surface morphological analysis respectively. The X-ray diffraction patterns reveal that the films have zinc-blende structure of single cubic phase with preferred orientation (111) and polycrystalline in nature. The crystallographic and optical parameters are calculated and discussed in brief. The optical band gap is found to be 1.62 eV and 1.52 eV for as-grown and annealed films respectively. The I-V characteristics show that the conductivity is decreased for annealed thin films. The AFM studies reveal that the surface roughness is observed to be increased for thermally annealed films.

  19. Production of high-quality amorphous silicon films by evaporative silane surface decomposition

    International Nuclear Information System (INIS)

    High-quality hydrogenated amorphous silicon films (a-Si:H) have been produced by decomposition of low-pressure silane gas on a very hot surface with deposition on a nearby, typically 210 0C substrate. A high-temperature tungsten filament provides the surface for heterogeneous thermal decomposition of the low-pressure silane and subsequent evaporation of atomic silicon and hydrogen. These evaporated species (primarily) induce a-Si:H growth on nearby substrates which are temperature controlled using a novel substrate holder. The light and dark conductivities, optical band gap, deposition rates, and light-soaking effects of preliminary films are reported. The decomposition-evaporation process has been examined using a mass spectrometer to directly detect the decomposition rate and the evaporated radical species. Based on this data and other information, a simplified model for the deposition process is suggested. The excellent film quality and the attributes of the deposition process make this technique, which was originally suggested by Wiessman, viable for the fast rate, large-area deposition of a-Si:H for solar cells and other applications

  20. Production and characterization of thin film group IIIB, IVB and rare earth hydrides by reactive evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Provo, James L., E-mail: jlprovo@verizon.net [Consultant, J.L. Provo Consulting, Trinity, Florida 34655-7179 (United States)

    2015-07-15

    A recent short history of reactive evaporation by D. M. Mattox [History Corner—A Short History of Reactive Evaporation, SVC Bulletin (Society of Vacuum Coaters, Spring 2014), p. 50–51] describes various methods for producing oxides, nitrides, carbides, and some compounds, but hydrides were not mentioned. A study was performed in the mid-1970s at the General Electric Company Neutron Devices Department in Largo, FL, by the author to study preparation of thin film hydrides using reactive evaporation and to determine their unique characteristics and properties. Films were produced of scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), and the rare earth praseodymium (Pr), neodymium (Nd), gadolinium (Gd), dysprosium (Dy), and erbium (Er) hydrides by hot crucible filament and electron beam evaporation in atmospheres of deuterium and tritium gases. All-metal vacuum systems were used and those used with tritium were dedicated for this processing. Thin film test samples 1000 nm thick were prepared on 1.27 cm diameter molybdenum disk substrates for each occluder (i.e., an element that can react with hydrogen to form a hydride) material. Loading characteristics as determined by gas-to-metal atomic ratios, oxidation characteristics as determined by argon–sputter Auger analysis, film structure as determined by scanning electron microscope analysis, and film stress properties as determined by a double resonator technique were used to define properties of interest. Results showed hydrogen-to-metal atomic ratios varied from 1.5 to 2.0 with near maximum loading for all but Pr and Nd occluders which correlated with the oxidation levels observed, with all occluder oxidation levels being variable due to vacuum system internal processing conditions and the materials used. Surface oxide levels varied from ∼80 Å to over 1000 Å. For most films studied, results showed that a maximum loading ratio of near 2.0 and a minimum surface oxide level of ∼80 Å could be

  1. Production and characterization of thin film group IIIB, IVB and rare earth hydrides by reactive evaporation

    International Nuclear Information System (INIS)

    A recent short history of reactive evaporation by D. M. Mattox [History Corner—A Short History of Reactive Evaporation, SVC Bulletin (Society of Vacuum Coaters, Spring 2014), p. 50–51] describes various methods for producing oxides, nitrides, carbides, and some compounds, but hydrides were not mentioned. A study was performed in the mid-1970s at the General Electric Company Neutron Devices Department in Largo, FL, by the author to study preparation of thin film hydrides using reactive evaporation and to determine their unique characteristics and properties. Films were produced of scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), and the rare earth praseodymium (Pr), neodymium (Nd), gadolinium (Gd), dysprosium (Dy), and erbium (Er) hydrides by hot crucible filament and electron beam evaporation in atmospheres of deuterium and tritium gases. All-metal vacuum systems were used and those used with tritium were dedicated for this processing. Thin film test samples 1000 nm thick were prepared on 1.27 cm diameter molybdenum disk substrates for each occluder (i.e., an element that can react with hydrogen to form a hydride) material. Loading characteristics as determined by gas-to-metal atomic ratios, oxidation characteristics as determined by argon–sputter Auger analysis, film structure as determined by scanning electron microscope analysis, and film stress properties as determined by a double resonator technique were used to define properties of interest. Results showed hydrogen-to-metal atomic ratios varied from 1.5 to 2.0 with near maximum loading for all but Pr and Nd occluders which correlated with the oxidation levels observed, with all occluder oxidation levels being variable due to vacuum system internal processing conditions and the materials used. Surface oxide levels varied from ∼80 Å to over 1000 Å. For most films studied, results showed that a maximum loading ratio of near 2.0 and a minimum surface oxide level of ∼80 Å could be

  2. Non-Evaporable Getter Thin Film Coatings for Vacuum Applications

    CERN Document Server

    Prodromides, A E

    2002-01-01

    Getters are solid materials capable of chemisorbing gas molecules on their surface: getters are chemical pumps. They are widely used for a variety of applications such as in particle accelerators, vacuum tubes, field-emission display (FED), inert gas purification systems, H2 plasma purification, hydrogen species recycling as in the Tokamak Fusion Test Reactor. Among the different Non-Evaporable Getter (NEG) materials tested, the TiZrV alloys have the lowest activation temperature. For this reason, the TiZrV coatings were the object of this work. In particular, the aim of this investigation was to understand how to optimise three important properties of TiZrV coatings: to achieve the lowest possible activation temperature (Ta), and to obtain the highest pumping speed and surface pumping capacity. This objective is important in the context of the Large Hadron Collider (LHC) accelerator, since, before this work, the understanding and the knowledge of the TiZrV coatings properties were insufficient to adopt it fo...

  3. Operating experience with solidification of radioactive waste by a thin-film evaporator

    International Nuclear Information System (INIS)

    In the nuclear power stations of GDR the rough radioactive waste includes borat-containing evaporator bottoms and spent ion exchanger resins. For its final disposal in deep geological formations (rock salt mines) this waste has to be solidified. The experience of one year lasting operation of a steam heated thin-film evaporator (heating surface 2 m3) for evaporator bottoms to be solidified with a solid content of 200-250 g/l are reported on. In short time such amount of water is abstracted from the rough waste that due to the borate content a hot high-viscous product passes from evaporator to waste drum and there solidifies like glass to monolith. The product quality depends on the adjustment of the flow-equilibrium in the evaporator. Boric acid is used as matrix for the radioactive residues. The residual water content of the solidified waste product was about 15-20%, the volume reduction was Vf=5...6. In order to be sure to get a solidified product a process control was achieved by visual observation of the product of evaporation using a view-window and a TV-camera. (orig.)

  4. Falling film evaporation on a single tube and on a tube bundle

    OpenAIRE

    Roques, Jean-François; Thome, John Richard

    2005-01-01

    This study is a contribution for the improvement of horizontal falling film heat exchangers. This type of evaporator has the potential to be widely used in the petrochemical industry, for the sea water desalination, or in the large refrigeration systems. An experimental test facility has been constructed in order to study the evaporation of the liquid refrigerant R-134a flowing on a vertical array of horizontal copper tubes with a length of 0.55 meter and a diameter of 19.1mm. Special care ha...

  5. Hopping conduction in evaporated cadmium telluride thin films

    International Nuclear Information System (INIS)

    Hopping conduction was observed in cadmium telluride thin films. At low temperature there is insufficient energy to excite electrons into the conduction band hence the dominant conduction mechanism is probably hopping. The activation energy ΔE, was found to be approximately 0.05 eV (thickness=400nm) and 0.08 eV (thickness=267nm). As the temperature was increased activation energy more widely spread levels became possible until kt∼0.4 eV, when free conduction was dominant

  6. Chemisorption kinetics of hydrogen on evaporated iron films

    Science.gov (United States)

    Shanabarger, M. R.

    1975-01-01

    An investigation is conducted of the kinetics of isothermal adsorption-desorption processes involving molecular hydrogen which is chemisorbed onto thin (20 to 50 A) polycrystalline Fe films at temperatures near 300 K. The results of the investigation indicate that chemisorption in the H2-Fe system occurs via a precursor state of molecularly adsorbed hydrogen. Contamination of the surface from unknown impurities in the gas phase is found to affect the number of available adsorption sites and to modify the prefactor for the absolute desorption rate constant for the precursor state.

  7. Characterization of nanostructured ZnO thin films deposited through vacuum evaporation

    Science.gov (United States)

    Maldonado, Arturo; Juarez, Héctor; Pacio, Mauricio; Perez, Rene

    2015-01-01

    Summary This work presents a novel technique to deposit ZnO thin films through a metal vacuum evaporation technique using colloidal nanoparticles (average size of 30 nm), which were synthesized by our research group, as source. These thin films had a thickness between 45 and 123 nm as measured by profilometry. XRD patterns of the deposited thin films were obtained. According to the HRSEM micrographs worm-shaped nanostructures are observed in samples annealed at 600 °C and this characteristic disappears as the annealing temperature increases. The films obtained were annealed from 25 to 1000 °C, showing a gradual increase in transmittance spectra up to 85%. The optical band gaps obtained for these films are about 3.22 eV. The PL measurement shows an emission in the red and in the violet region and there is a correlation with the annealing process. PMID:25977868

  8. Characterization of nanostructured ZnO thin films deposited through vacuum evaporation

    Directory of Open Access Journals (Sweden)

    Jose Alberto Alvarado

    2015-04-01

    Full Text Available This work presents a novel technique to deposit ZnO thin films through a metal vacuum evaporation technique using colloidal nanoparticles (average size of 30 nm, which were synthesized by our research group, as source. These thin films had a thickness between 45 and 123 nm as measured by profilometry. XRD patterns of the deposited thin films were obtained. According to the HRSEM micrographs worm-shaped nanostructures are observed in samples annealed at 600 °C and this characteristic disappears as the annealing temperature increases. The films obtained were annealed from 25 to 1000 °C, showing a gradual increase in transmittance spectra up to 85%. The optical band gaps obtained for these films are about 3.22 eV. The PL measurement shows an emission in the red and in the violet region and there is a correlation with the annealing process.

  9. ZnS thin films deposition by thermal evaporation for photovoltaic applications

    International Nuclear Information System (INIS)

    ZnS thin films were deposited on glass substrates by thermal evaporation from millimetric crystals of ZnS. The structural, compositional and optical properties of the films are studied by X-ray diffraction, SEM microscopy, and UV–VIS spectroscopy. The obtained results show that the films are pin hole free and have a cubic zinc blend structure with (111) preferential orientation. The estimated optical band gap is 3.5 eV and the refractive index in the visible wavelength ranges from 2.5 to 1.8. The good cubic structure obtained for thin layers enabled us to conclude that the prepared ZnS films may have application as buffer layer in replacement of the harmful CdS in CIGS thin film solar cells or as an antireflection coating in silicon-based solar cells. (paper)

  10. 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.

  11. Modelling approaches to the dewetting of evaporating thin films of nanoparticle suspensions

    Science.gov (United States)

    Thiele, U.; Vancea, I.; Archer, A. J.; Robbins, M. J.; Frastia, L.; Stannard, A.; Pauliac-Vaujour, E.; Martin, C. P.; Blunt, M. O.; Moriarty, P. J.

    2009-07-01

    We review recent experiments on dewetting thin films of evaporating colloidal nanoparticle suspensions (nanofluids) and discuss several theoretical approaches to describe the ongoing processes including coupled transport and phase changes. These approaches range from microscopic discrete stochastic theories to mesoscopic continuous deterministic descriptions. In particular, we describe (i) a microscopic kinetic Monte Carlo model, (ii) a dynamical density functional theory and (iii) a hydrodynamic thin film model. Models (i) and (ii) are employed to discuss the formation of polygonal networks, spinodal and branched structures resulting from the dewetting of an ultrathin 'postcursor film' that remains behind a mesoscopic dewetting front. We highlight, in particular, the presence of a transverse instability in the evaporative dewetting front, which results in highly branched fingering structures. The subtle interplay of decomposition in the film and contact line motion is discussed. Finally, we discuss a simple thin film model (iii) of the hydrodynamics on the mesoscale. We employ coupled evolution equations for the film thickness profile and mean particle concentration. The model is used to discuss the self-pinning and depinning of a contact line related to the 'coffee-stain' effect. In the course of the review we discuss the advantages and limitations of the different theories, as well as possible future developments and extensions.

  12. Modelling approaches to the dewetting of evaporating thin films of nanoparticle suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Thiele, U; Vancea, I; Archer, A J; Robbins, M J; Frastia, L [Department of Mathematical Sciences, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Stannard, A; Pauliac-Vaujour, E; Martin, C P; Blunt, M O; Moriarty, P J [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)], E-mail: u.thiele@lboro.ac.uk

    2009-07-01

    We review recent experiments on dewetting thin films of evaporating colloidal nanoparticle suspensions (nanofluids) and discuss several theoretical approaches to describe the ongoing processes including coupled transport and phase changes. These approaches range from microscopic discrete stochastic theories to mesoscopic continuous deterministic descriptions. In particular, we describe (i) a microscopic kinetic Monte Carlo model, (ii) a dynamical density functional theory and (iii) a hydrodynamic thin film model. Models (i) and (ii) are employed to discuss the formation of polygonal networks, spinodal and branched structures resulting from the dewetting of an ultrathin 'postcursor film' that remains behind a mesoscopic dewetting front. We highlight, in particular, the presence of a transverse instability in the evaporative dewetting front, which results in highly branched fingering structures. The subtle interplay of decomposition in the film and contact line motion is discussed. Finally, we discuss a simple thin film model (iii) of the hydrodynamics on the mesoscale. We employ coupled evolution equations for the film thickness profile and mean particle concentration. The model is used to discuss the self-pinning and depinning of a contact line related to the 'coffee-stain' effect. In the course of the review we discuss the advantages and limitations of the different theories, as well as possible future developments and extensions.

  13. Modelling approaches to the dewetting of evaporating thin films of nanoparticle suspensions

    International Nuclear Information System (INIS)

    We review recent experiments on dewetting thin films of evaporating colloidal nanoparticle suspensions (nanofluids) and discuss several theoretical approaches to describe the ongoing processes including coupled transport and phase changes. These approaches range from microscopic discrete stochastic theories to mesoscopic continuous deterministic descriptions. In particular, we describe (i) a microscopic kinetic Monte Carlo model, (ii) a dynamical density functional theory and (iii) a hydrodynamic thin film model. Models (i) and (ii) are employed to discuss the formation of polygonal networks, spinodal and branched structures resulting from the dewetting of an ultrathin 'postcursor film' that remains behind a mesoscopic dewetting front. We highlight, in particular, the presence of a transverse instability in the evaporative dewetting front, which results in highly branched fingering structures. The subtle interplay of decomposition in the film and contact line motion is discussed. Finally, we discuss a simple thin film model (iii) of the hydrodynamics on the mesoscale. We employ coupled evolution equations for the film thickness profile and mean particle concentration. The model is used to discuss the self-pinning and depinning of a contact line related to the 'coffee-stain' effect. In the course of the review we discuss the advantages and limitations of the different theories, as well as possible future developments and extensions.

  14. Transmission Electron Microscope Studies of Thin Films of CdSe Vacuum Evaporated from Knudsen-Type Source

    Directory of Open Access Journals (Sweden)

    K. L. Chaudhary

    1998-07-01

    Full Text Available A Knudsen-type evaporation source was used for the vacuum deposition of thin films of CdSe to study their growth and microstructure on to air-cleaved KCI and mica substrates under different rates of evaporation and substrate temperatures. The conditions for the growth of epitaxial films of this material onto mica have also been established and their photoconducting properties evaluated. CdSe films prepared by this source retain their stoichiometry and compare well with those prepared by other sources of vacuum evaporation.

  15. Evaluation of thin-film evaporation for decontamination and immobilization of aqueous nuclear waste

    International Nuclear Information System (INIS)

    In the early 1980's, AECL, at the Chalk River Laboratory (CRL) site, built a Waste Treatment Centre (WTC) for managing low level solid and aqueous liquid wastes. The objective was to demonstrate processes for converting Canadian Deuterium Uranium (CANDU) waste to a form suitable for disposal while meeting or exceeding current environmental regulations. At present, two liquid waste streams are being treated at the Waste Treatment Centre. The liquid waste streams are volume reduced by a combination of continuous crossflow microfiltration (MF), spiral wound reverse osmosis (SWRO), and tubular reverse osmosis (TRO) membrane technologies [1]. The solutions are evaporated while simultaneously adding bitumen in a thin-film evaporator. A water-free product of chemical and radiochemical salts and bitumen is removed in 200 L galvanized steel drums for storage and eventual disposal in the CRL Waste Management Area. The feed stream to the thin-film evaporator typically has a β/γ activity of about 1 - 3 μCi/mL. This intermediate-level radioactive stream is concentrated by a factor of about 10, while simultaneously being immobilized. The radiation field of product drums on contact typically has a value of 0.5 to 3 R/h depending upon the feed concentration of radioactivity to the evaporator. The total solids content in the 200 L drum ranges from 25% to 35%. Encapsulated in the bitumen matrix are a variety of non-radiochemical salts (including sodium phosphate, sodium sulphate, and sodium carbonate) which comprise the bulk of the total solids in the product drum. The drum contains less than 1% of free water. The paper will discuss the volume reduction capability of the plant, with an emphasis on the immobilization of the aqueous waste with bitumen in a thin-film evaporator. Operations experience gained from over 200 campaigns is documented in the paper. (author)

  16. Microstructural Characterization of Au-In Thin Film Deposited by Electron Beam Evaporation

    International Nuclear Information System (INIS)

    The microstructure and phase formation of Au-In thin film deposited by e-beam evaporation technique has been studied. Single crystals of rock salt were used as the substrates. The chamber pressure during deposition was about 2.5 x 10-5 torr and substrate temperature was 35 degree Celsius. Three types of samples were prepared namely Au, In and Au-In thin films. Microstructure and chemical composition of these thin films were characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectrometer (XPS) respectively. TEM micrograph reveals island structures for both Au and In thin film on the rock salt substrate, with the In island size distribution is about 9-30 nm compared to Au island in the range of 3-10 nm. The growth of islands instead of smooth film indicates that Au and In thin films follow the Volmer-Weber growth mode. However, island structures were not present on Au-In thin films which most probably follow the Frank van de Merwe growth mode. XPS analysis indicates intermetallic compound was not present in the Au-In thin film suggesting that diffusion process in the interface of Au and In films is minimal. (author)

  17. Microstructures of the electron-beam evaporated InSb thin films

    International Nuclear Information System (INIS)

    Polycrystalline InSb thin films have been prepared by the two-source electron-beam evaporation method. The InSb films have been grown on both pure Si (100) substrate and on Si (100) substrate which has been thermally oxidized to form a thin amorphous SiOx overlayer. The as-grown thin films have been heat treated under N2 atmosphere which is slightly mixed with air. A thin InOx layer is formed on the top surface of the thin film. After heat treatment, the InSb films grown on the oxidized Si substrate shows a preferred (111) orientation. While the films grown on Si substrate do not show such preferred orientation as evidenced by the x-ray diffraction patterns. The TEM cross sectional morphologies of the InSb film grown on oxidized Si substrate shows an ordered arrangement of the grains. While the film grown on the pure Si substrate shows a random arrangement of the grains. The film grown on the oxidized Si substrate also shows the existence of the twin boundary and an ordered arrangement of the precipitation of the second phase

  18. Study of the influence of semiconductor material parameters on acoustic wave propagation modes in GaSb/AlSb bi-layered structures by Legendre polynomial method

    Science.gov (United States)

    Othmani, Cherif; Takali, Farid; Njeh, Anouar; Ben Ghozlen, Mohamed Hédi

    2016-09-01

    The propagation of Rayleigh-Lamb waves in bi-layered structures is studied. For this purpose, an extension of the Legendre polynomial (LP) method is proposed to formulate the acoustic wave equation in the bi-layered structures induced by thin film Gallium Antimonide (GaSb) and with Aluminum Antimonide (AlSb) substrate in moderate thickness. Acoustic modes propagating along a bi-layer plate are shown to be quite different than classical Lamb modes, contrary to most of the multilayered structures. The validation of the LP method is illustrated by a comparison between the associated numerical results and those obtained using the ordinary differential equation (ODE) method. The convergency of the LP method is discussed through a numerical example. Moreover, the influences of thin film GaSb parameters on the characteristics Rayleigh-Lamb waves propagation has been studied in detail. Finally, the advantages of the Legendre polynomial (LP) method to analyze the multilayered structures are described. All the developments performed in this work were implemented in Matlab software.

  19. Attractive mechanical properties of a lightweight highly sensitive bi layer thermistor: polycarbonate/organic molecular conductor

    Science.gov (United States)

    Laukhina, E.; Lebedev, V.; Rovira, C.; Laukhin, V.; Veciana, J.

    2016-03-01

    The paper covers some of the basic mechanical characteristics of a recently developed bi layer thermistor: polycarbonate/(001) oriented layer of organic molecular conductor α’-(BEDT-TTF)2IxBr3-x, were BEDT-TTF=bis(ethylenedithio)tetrathiafulvalen. The nano and macro mechanical properties have been studied in order to use this flexible, low cost thermistor in sensing applications by proper way. The nano-mechanical properties of the temperature sensitive semiconducting layer of α’-(BEDT-TTF)2IxBr3-x were tested using nanoindentation method. The value of Young's modulus in direction being perpendicular to the layer plan was found as 9.0 ±1.4 GPa. The macro mechanical properties of the thermistor were studied using a 5848 MicroTester. The tensile tests showed that basic mechanical characteristics of the thermistor are close to those of polycarbonate films. This indicates a good mechanical strength of the developed sensor. Therefore, the thermistor can be used in technologies that need to be instrumented with highly robustness lightweight low cost temperature sensors. The paper also reports synthetic details on fabricating temperature sensing e-textile. As the temperature control is becoming more and more important in biomedical technologies like healthcare monitoring, this work strongly contributes on the ongoing research on engineering sensitive conducting materials for biomedical applications.

  20. Numerical simulation and modeling of liquid film evaporation inside axisymmetric reentrant cavities

    Directory of Open Access Journals (Sweden)

    Dietl Jochen

    2014-01-01

    Full Text Available Evaporation of thin liquid films inside reentrant cavities occurs in several boiling processes where enhanced surfaces are utilized. In this work, evaporation from a single reentrant cavity with an additional thin channel is studied. The channel allows the backflow of liquid from the pool into the cavity during bubble growth. Direct numerical simulations were performed, showing a strong relation between flow to the film inside the cavity and bubble growth at the pore. Additionally, a model was created with a novel modeling approach which is based on solving the Young-Laplace equation. From the model characteristic nondimensional parameters can be obtained and the influence of geometry variations on hydrodynamics can be studied.

  1. Study on heat transfer for falling liquid film flow with consideration of interfacial evaporation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The interfacial evaporative heat transfer was included in the semi-empirical study of the heat transfer for the falling liquid film flow. The investigations showed that, the inclusion of the interfacial evaporative heat transfer in the turbulent model would lower the predicted convective heat transfer coefficient. Predictions of the new model resulted in a prominent deviation from that predictions of the normal model in the case of large mass flow rate and low wall heat flux. This deviation will be decreased with increasing wall heat flux, such that it will be asymptotic zero at very high wall heat flux. Predictions of the new model agreed well with the current experimental measurements. This study has verified that the Reynolds number is not the sole crucial parameter for heat transfer of falling liquid film flow, and wall heat flux will be another important independent parameter. This result is consistent with our previous studies.

  2. Spin-pump-induced spin transport in a thermally evaporated pentacene film

    Energy Technology Data Exchange (ETDEWEB)

    Tani, Yasuo; Shikoh, Eiji, E-mail: shikoh@elec.eng.osaka-cu.ac.jp [Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Teki, Yoshio [Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)

    2015-12-14

    We report the spin-pump-induced spin transport properties of a pentacene film prepared by thermal evaporation. In a palladium(Pd)/pentacene/Ni{sub 80}Fe{sub 20} tri-layer sample, a pure spin-current is generated in the pentacene layer by the spin-pumping of Ni{sub 80}Fe{sub 20}, which is independent of the conductance mismatch problem in spin injection. The spin current is absorbed into the Pd layer, converted into a charge current with the inverse spin-Hall effect in Pd, and detected as an electromotive force. This is clear evidence for the pure spin current at room temperature in pentacene films prepared by thermal evaporation.

  3. Use of a thin-film evaporator for bitumen coating of radioactive concentrates

    International Nuclear Information System (INIS)

    Following the development in the laboratory of a process for coating evaporation concentrates with bitumen, a technological study of this coating process has been undertaken. The report describes a pilot installation for the bitumen coating of concentrates, which uses a thin-film evaporator LUWA L 150. The first, inactive series of tests was designed to determine the maximum and optimum capacities of the evaporator by varying the amounts of bitumen and of concentrate, the rotor speed and the thermo-fluid temperature. Two rotors were tested, one of conventional type, the other a model especially designed for high viscosity products. The maximum capacity of evaporation of the apparatus is 72 kg/hr for a heating temperature of 221 deg. C. During normal operation, the evaporator can produce 50 kg/hr of coated product containing 55 to 60 per cent of bitumen (Mexphalte 40/50), the water content of the product remaining under 0.5 per cent. A second series of tests will shortly be carried out on this pilot installation using, in particular, bituminous emulsions containing mainly Mexphalte 40/50 and 80/100. (authors)

  4. Numerical investigation of evaporation and condensation of thin films in conjugated heat transfer systems

    OpenAIRE

    Sosnowski, Pawel

    2013-01-01

    Evaporation and condensation of thin liquid films on solid surfaces are common elements of industrial processes. In many cases they have a significant impact on the physics of the studied case. At the same time, experimental studies can prove to be troublesome, mostly because of the amount of possible setups, complex geometries of interest, numerous materials being used and cost. For that reason it is reasonable to study this phenomena using numerical methods. Having the advantage in speed an...

  5. Bi-layer ^3He: a simple two dimensional heavy fermion system with quantum criticality

    Science.gov (United States)

    Saunders, John

    2008-03-01

    Two dimensional helium films provide simple model systems for the investigation of quantum phase transitions in two dimensions. Monolayer ^3He absorbed on graphite, with various pre-platings, behaves as a two dimensional Mott-Hubbard system, complete with a density driven ``metal-insulator'' transition [1, 2] into what appears to be a gapless spin-liquid. In two dimensions the corrections to the temperature dependence of the fluid heat capacity, beyond the term linear in T, are anomalous and attributed to quasi-1D scattering [3]. On the other hand, bi-layer ^3He films adsorbed on the surface of graphite show evidence of two-band heavy-fermion behavior and quantum criticality [4, 5]. The relevant control parameter is the total density of the ^3He film. The ^3He bilayer system can be driven toward a quantum critical point (QCP) at which the effective mass appears to diverge, the effective inter-band hybridization vanishes, and a local moment state appears. A theoretical model in terms of a ``Kondo breakdown selective Mott transition'' has recently been suggested [6]. * In collaboration with: A Casey, M Neumann, J Nyeki, B Cowan. [1] Evidence for a Mott-Hubbard Transition in a Two-Dimensional ^3He Fluid Monolayer, A. Casey, H. Patel, J. Ny'eki, B. P. Cowan, and J. Saunders Phys. Rev. Lett. 90, 115301 (2003) [2] D Tsuji et al. J. Low Temp. Phys. 134, 31 (2004) [3] A V Chubukov et al. Phys. Rev. B71, 205112 (2005) [4] Bilayer ^3He; a simple two dimensional heavy fermion system with quantum criticality, Michael Neumann, Jan Nyeki, Brian Cowan, John Saunders. Science 317, 1356 (2007) [5] Heavy fermions in the original Fermi liquid. Christopher A Hooley and Andrew P Mackenzie. Science 317, 1332 (2007) [6] C Pepin, Phys. Rev. Lett. 98, 206401 (2007) and A Benlagra and C Pepin, arXiv: 0709.0354

  6. Study of thermally evaporated thin permalloy films by the Fresnel mode of TEM and AFM

    International Nuclear Information System (INIS)

    Highlights: ► Thermally evaporated thin permalloy films 10 nm and 60 nm thick were investigated. ► The magnetic structure consisted of in-plane magnetized domains 10–30 μm in size. ► The domain walls of Néel type and cross-tie walls were observed. ► Cross-tie walls in the films 10 nm thick were observed for the first time. ► The morphological structure was composed of nanocrystalline grains. - Abstract: Thin permalloy films 10 nm and 60 nm thick were investigated. They were thermally evaporated at an incidence angle of 0° in a vacuum of about 10−5 mbar. The magnetic structure of the films was observed with the Fresnel mode of transmission electron microscopy (TEM), while their morphological structure was revealed using atomic force microscopy (AFM). The magnetic structure consisted of domains typically 10–30 μm in size. The films were substantially magnetized in the plane of the film. The domain walls of Néel type as well as cross-tie walls occurred in the films 10 nm thick, while in the films 60 nm thick the presence of cross-tie walls was only observed. The presence of cross-tie walls in the films 10 nm thick is reported for the first time. The coexistence of Néel type and cross-tie walls in the films 10 nm thick means that their wall energies are comparable at this film thickness, and this statement is supported by the results of theoretical works. The morphological structure of the films was composed of nanocrystalline grains smaller than about 30 nm in size; the films 60 nm thick had grains somewhat larger in size than the films 10 nm thick. The random distribution of the magnetocrystalline anisotropy of the individual nanocrystalline grains is found to be practically averaged out by exchange interaction, which leads consequently to the strongly reduced effective magnetic anisotropy and the wide magnetic domains on a 10 μm scale.

  7. Functional porphyrin thin films deposited by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Atomistilor 409, Bucharest-Magurele (Romania); Popescu, C.; Popescu, A.C.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Atomistilor 409, Bucharest-Magurele (Romania); Ciucu, A.A. [Univeristy of Bucharest, Chemistry Department, Bucharest (Romania); Andronie, A.; Iordache, S.; Stamatin, I. [University of Bucharest, 3 Nano-SAE Research Center, P.O. Box MG-38, Bucharest-Magurele (Romania); Fagadar-Cosma, E. [Institute of Chemistry Timisoara of Romanian Academy, Department of Organic Chemistry, 300223 Timisoara (Romania); Chrisey, D.B. [Rensselaer Polytechnic Institute, School of Engineering, Department of Materials Science and Engineering, Troy 12180-3590, NY (United States)

    2010-05-25

    We report the first successful deposition of functionalized and nanostructured Zn(II)- and Co(II)-metalloporphyrin thin films by matrix assisted pulsed laser evaporation onto silicon wafers, quartz plates and screen-printed electrodes. The deposited nanostructures have been characterized by Raman spectrometry and cyclic voltammetry. The novelty of our contribution consists of the evaluation of the sensitivity of the MAPLE-deposited Zn(II)- and Co(II)-metalloporphyrin thin films on screen-printed carbon nanotube electrodes when challenged with dopamine.

  8. Electroluminescence and its excitation mechanism of SiOx films deposited by electron-beam evaporation

    International Nuclear Information System (INIS)

    Blue electroluminescence from SiOx films deposited by electron beam evaporation was observed. This blue emission blueshifted from 450 to 410 nm with increasing applied voltage. The dependences of blue emission on applied voltage, frequency and conduction current were studied. Our experimental data support that blue emission from SiOx films is the result of both recombination of charge carriers injected from opposite electrodes and impact excitation of hot electrons, the recombination of carriers injected is dominant in low and medium electric fields but hot electron impact excitation is dominant under high electric fields

  9. Dynamic Scaling in Growth of ZrO2 Thin Films Prepared by Electronic Beam Evaporation

    Institute of Scientific and Technical Information of China (English)

    齐红基; 黄立华; 袁景梅; 程传福; 邵建达; 范正修

    2003-01-01

    The growth front evolution of ZrO2 thin films deposited by electronic beam evaporation has been studied with atomic force microscopy. The dynamic scaling characteristics are observed during the deposition process. After numerical correlation analysis, the roughness exponent α = 0.80 ± 0.005 and the growth exponentβ = 0.141are all obtained. Based on these results, we suggest that the growth of ZrO2 thin films can be described by the combination of the Edwards-Wilkinson equation, the Mullins diffusion equation and the shadowing effect.

  10. Functional polyethylene glycol derivatives nanostructured thin films synthesized by matrix-assisted pulsed laser evaporation

    International Nuclear Information System (INIS)

    We report the thin film deposition by matrix-assisted pulsed laser evaporation (MAPLE) of a polymer conjugate with an hydrophilic sequence between metronidazole molecules that was covalently attached to both oligomer ends of carboxylate poly(ethylene glycol) (PEG 1.5-metronidazole). A pulsed KrF* excimer laser was used to deposit the drug-polymer composite films. Fourier transform infrared spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical properties similar to the starting materials. The dependence of the surface morphology on incident laser fluence is given.

  11. Functional polyethylene glycol derivatives nanostructured thin films synthesized by matrix-assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, Bucharest-Magurele (Romania); Popescu, C.; Popescu, A.; Grigorescu, S.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, Bucharest-Magurele (Romania); Mihaiescu, D. [University of Agriculture Sciences and Veterinary Medicine, 59 Marasti, Bucharest (Romania); Gittard, S.D.; Narayan, R.J. [Biomedical Engineering, University of North Carolina, Chapel Hill, NC (United States); Buruiana, T. [Petru Poni Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda, 41A, Iasi (Romania); Stamatin, I. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Chrisey, D.B. [Rensselaer Polytechnic Institute, Department of Materials Science and Engineering, Troy, NY (United States)

    2009-09-30

    We report the thin film deposition by matrix-assisted pulsed laser evaporation (MAPLE) of a polymer conjugate with an hydrophilic sequence between metronidazole molecules that was covalently attached to both oligomer ends of carboxylate poly(ethylene glycol) (PEG 1.5-metronidazole). A pulsed KrF* excimer laser was used to deposit the drug-polymer composite films. Fourier transform infrared spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical properties similar to the starting materials. The dependence of the surface morphology on incident laser fluence is given.

  12. Functional porphyrin thin films deposited by matrix assisted pulsed laser evaporation

    International Nuclear Information System (INIS)

    We report the first successful deposition of functionalized and nanostructured Zn(II)- and Co(II)-metalloporphyrin thin films by matrix assisted pulsed laser evaporation onto silicon wafers, quartz plates and screen-printed electrodes. The deposited nanostructures have been characterized by Raman spectrometry and cyclic voltammetry. The novelty of our contribution consists of the evaluation of the sensitivity of the MAPLE-deposited Zn(II)- and Co(II)-metalloporphyrin thin films on screen-printed carbon nanotube electrodes when challenged with dopamine.

  13. Electrical properties of silver selenide thin films prepared by reactive evaporation

    Indian Academy of Sciences (India)

    M C Santhosh Kumar; B Pradeep

    2002-10-01

    The electrical properties of silver selenide thin films prepared by reactive evaporation have been studied. Samples show a polymorphic phase transition at a temperature of 403 ± 2 K. Hall effect study shows that it has a mobility of 2000 cm2V–1s–1 and carrier concentration of 1018 cm–3 at room temperature. The carriers are of -type. X-ray diffraction study indicates that the as-prepared films are polycrystalline in nature. The lattice parameters were found to be = 4.353 Å, = 6.929 Å and = 7.805 Å.

  14. Electrical bistable characteristics of poly (phenylene sulfide) thin film deposited by thermal evaporation

    Institute of Scientific and Technical Information of China (English)

    GUO XiaoChun; DONG GuiFang; QIU Yong

    2007-01-01

    Poly(phenylene sulfide) (PPS) is a well-known organic insulator. However, the PPS thin film, deposited by thermal evaporation in vacuum, showed electrical bistable characteristics. The structure of the PPS thin-film device was glass/ITO/PPS (300 nm)/Au. The thin film can be converted to a high conductance state by applying a pulse of 80 V (5 s), and brought back to a low conductance state by applying a pulse of 100 V (5 s). This kind of thin film is potential for active layer of a memory device. The critical voltage of the device is about 40 V, while the read-out voltage is 5 V. We tentatively ascribe the bistable phenomenon to the charge transfer from S to C atoms in the PPS molecule chains.

  15. Thin films' thickness uniformity associated with the method of electron beam evaporation

    Science.gov (United States)

    Xia, Zhilin; Xue, Yiyu; Guo, Peitao; Li, Zhangwang

    2009-08-01

    Coating material has been considered as being made up of a lot of small tablets. These tablets have plane surface during the whole film preparation process. Based on the assumption that a column etching pit will form in coating material when electron beam is used for heating, influences of the etching pit's dimension and the internal structure of the vacuum chamber on films thickness uniformity have been investigated. Results reflect that the appearance of etching pit does not always cause negative influence on films thickness uniformity. The negative impact of etching on films thickness uniformity can be reduced by optimizing the internal structure of the vacuum chamber and preparation technical parameters. But, it is difficult to achieve the beneficial action. This investigation is useful to help us understand physical meaning of the emission characteristics of the evaporation particle and design experimental scheme.

  16. Infrared waveguide fabrications with an E-beam evaporated chalcogenide glass film

    KAUST Repository

    Yang, Xiaoming

    2014-12-12

    Chalcogenide glasses have a variety of unique optical properties due to the intrinsic structural flexibility and bonds metastability. They are desirable materials for many applications, such as infrared communication sensors, holographic grating, optical imaging, and ultrafast nonlinear optic devices. Here, we introduce a novel electron-beam evaporation process to deposit the good quality arsenic trisulfide (As2S3) films and then the As2S3 films were used to fabricate the As2S3 waveguides with three approaches. The first method is photoresist lift-off. Because of the restriction of thermal budget of photoresist, the As2S3 film must be deposited at the room temperature. The second one is the silicon dioxide lift-off process on sapphire substrates, in which the As2S3 film could be evaporated at a high temperature (>180 °C) for better film quality. The third one is the plasma etching process with a metal protective thin layer in the pattern development process.

  17. Microstructure and crystal imperfections of nanosized CdSxSe1-x thermally evaporated thin films

    Science.gov (United States)

    Akl, Alaa A.; Hassanien, A. S.

    2015-09-01

    Cadmium sulfoselenide CdSxSe1-x thin films were thermally evaporated onto preheated glass substrates (523 K). The evaporation rate and film thickness were kept constant at ≈2.5 nm/s and 375 ± 5 nm, respectively. Microstructure and crystal imperfections of deposit CdSxSe1-x thin films were studied using X-ray diffraction (XRD) and energy dispersive analysis by X-ray (EDAX). XRD analysis reveals the formation of films have the semi-crystalline nature and the hexagonal structure with preferential direction. The microstructural parameters such as, lattice parameters, the crystallite size (D), microstrain , residual internal stress (S), dislocation density (δ) and number of crystallite per unit volume (N) were calculated and found to be dependent upon the composition. The presence percentage of Cd, S and Se elements in the chalcogenide CdSxSe1-x thin films were estimated by EDAX and a comparative study with other similar samples of the previous literature was discussed.

  18. Fabrication of thermally evaporated Al thin film on cylindrical PET monofilament for wearable computing devices

    Science.gov (United States)

    Liu, Yang; Kim, Eunju; Han, Jeong In

    2016-01-01

    During the initial development of wearable computing devices, the conductive fibers of Al thin film on cylindrical PET monofilament were fabricated by thermal evaporation. Their electrical current-voltage characteristics curves were excellent for incorporation into wearable devices such as fiber-based cylindrical capacitors or thin film transistors. Their surfaces were modified by UV exposure and dip coating of acryl or PVP to investigate the surface effect. The conductive fiber with PVP coating showed the best conductivities because the rough surface of the PET substrate transformed into a smooth surface. The conductivities of PET fiber with and without PVP were 6.81 × 103 Ω-1cm-1 and 5.62 × 103 Ω-1cm-1, respectively. In order to understand the deposition process of Al thin film on cylindrical PET, Al thin film on PET fiber was studied using SEM (Scanning Electron Microscope), conductivities and thickness measurements. Hillocks on the surface of conductive PET fibers were observed and investigated by AFM on the surface. Hillocks were formed and grown during Al thermal evaporation because of severe compressive strain and plastic deformation induced by large differences in thermal expansion between PET substrate and Al thin film. From the analysis of hillock size distribution, it turns out that hillocks grew not transversely but longitudinally. [Figure not available: see fulltext.

  19. Heat capacity of quantum adsorbates: Hydrogen and helium on evaporated gold films

    International Nuclear Information System (INIS)

    The author has constructed an apparatus to make specific heat measurements of quantum gases adsorbed on metallic films at temperatures between 0.3 and 4 K. He has used this apparatus to study quench-condensed hydrogen films between 4 and 923 layers thick with J = 1 concentrations between 0.28 and 0.75 deposited on an evaporated gold surface. He has observed that the orientational ordering of the J = 1 molecules depends on the substrate temperature during deposition of the hydrogen film. He has inferred that the density of the films condensed at the lowest temperatures is 25% higher than in bulk H2 crystals and have observed that the structure of those films is affected by annealing at 3.4 K. The author has measured the J = 1 to J = 0 conversion rate to be comparable to that of the bulk for thick films; however, he found evidence that the gold surface catalyzes conversion in the first two to four layers. He has also used this apparatus to study films of 4He less than one layer thick adsorbed on an evaporated gold surface. He shows that the phase diagram of the system is similar to that for 4He/graphite although not as rich in structure, and the phase boundaries occur at different coverages and temperatures. At coverages below about half a layer and at sufficiently high temperatures, the 4He behaves like a two-dimensional noninteracting Bose gas. At lower temperatures and higher coverages, liquidlike and solidlike behavior is observed. The Appendix shows measurements of the far-infrared absorptivity of the high-Tc superconductor La1.87Sr0.13CuO4

  20. Electrical and Optical Properties of GeSi−:H Thin Films Prepared by Thermal Evaporation Method

    Directory of Open Access Journals (Sweden)

    A. A. J. Al-Douri

    2010-01-01

    Full Text Available Thin a-GeSi1−:H films were grown successfully by fabrication of designated ingot followed by evaporation onto glass slides. A range of growth conditions, Ge contents, dopant concentration (Al and As, and substrate temperature, were employed. Stoichiometry of the thin films composition was confirmed using standard surface techniques. The structure of all films was amorphous. Film composition and deposition parameters were investigated for their bearing on film electrical and optical properties. More than one transport mechanism is indicated. It was observed that increasing substrate temperature, Ge contents, and dopant concentration lead to a decrease in the optical energy gap of those films. The role of the deposition conditions on values of the optical constants was determined. Accordingly, models of the density of states for the Ge0.5Si0.5:H thin films as pure, doped with 3.5% of Al (p-type and that doped with 3.5% As (n-type, were proposed.

  1. Structural, optical, photoluminescence, dielectric and electrical studies of vacuum-evaporated CdTe thin films

    Indian Academy of Sciences (India)

    Ziaul Raza Khan; M Zulfequar; Mohd Shahid Khan

    2012-04-01

    Highly-oriented CdTe thin films were fabricated on quartz and glass substrates by thermal evaporation technique in the vacuum of about 2 × 10-5 torr. The CdTe thin films were characterized by X-ray diffraction (XRD), UV–VIS–NIR, photoluminescence spectroscopy and scanning electron microscopy (SEM). X-ray diffraction results showed that the films were polycrystalline with cubic structure and had preferred growth of grains along the (111) crystallographic direction. Scanning electron micrographs showed that the growth of crystallites of comparable size on both the substrates. At the room temperature, photoluminescence spectra of the films on both the substrates showed sharp peaks with a maximum at 805 nm. This band showed significant narrowing suggesting that it originates from the transitions involving grain boundary defects. The refractive index of CdTe thin films was calculated using interference pattern of transmission spectra. The optical band gap of thin films was found to allow direct transition with energy gap of 1.47–1.50 eV. a.c. conductivity of CdTe thin films was found to increase with the increase in frequency whereas dielectric constant was observed to decrease with the increase in frequency.

  2. Photoluminescence of electron beam evaporated CaS:Bi thin films

    CERN Document Server

    Smet, P F; Poelman, D R; Meirhaeghe, R L V

    2003-01-01

    For the first time, the photoluminescence (PL) of electron beam evaporated CaS:Bi thin films is reported. Luminescent CaS:Bi powder prepared out of aqueous solutions was used as source material. The influence of substrate temperature on the PL and the morphology of thin films is discussed, and an optimum is determined. Substrate temperatures between 200 deg. C and 300 deg. C lead to good quality thin films with sufficient PL intensity. As-deposited thin films show two emission bands, peaking at 450 and 530 nm. Upon annealing the emission intensity increases, and annealing at 800 deg. C is sufficient to obtain a homogeneously blue emitting thin film (CIE colour coordinates (0.17; 0.12)), thanks to a single remaining emission band at 450 nm. The influence of ambient temperature on the PL of CaS:Bi powder and thin films was also investigated and it was found that CaS:Bi thin films show a favourable thermal quenching behaviour near room temperature.

  3. Ferroelectric characterization and growth optimization of thermally evaporated vinylidene fluoride thin films

    Science.gov (United States)

    Foreman, K.; Hong, N.; Labedz, C.; Shearer, M.; Ducharme, Stephen; Adenwalla, S.

    2016-01-01

    Organic thin films have numerous advantages over inorganics in device processing and price. The large polarization of the organic ferroelectric oligomer vinylidene fluoride (VDF) could prove useful for both device applications and the investigation of fundamental physical phenomena. A VDF oligomer thin film vacuum deposition process, such as thermal evaporation, preserves film and interface cleanliness, but is challenging, with successful deposition occurring only within a narrow parameter space. We report on the optimal deposition parameters for VDF oligomer thin films, refining the parameter space for successful deposition, resulting in a high yield of robust ferroelectric films. In particular, we investigate the influence of deposition parameters on surface roughness, and the role that roughness plays in sample yield. The reliable production of ferroelectric films allowed us to perform detailed measurements of previously unreported properties, including the Curie temperature, the temperature and thickness dependence of the coercive field, the melting temperature, and the index of refraction. The ability to successfully grow robust, switchable, well-characterized films makes VDF oligomer a viable candidate in the field of organic ferroelectrics.

  4. 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)

  5. CdS thin films growth by fast evaporation with substrate rotation

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Rodriguez, R., E-mail: romano@mda.cinvestav.mx [Applied Physics Department, CINVESTAV-IPN Merida, C.P. 97310, Merida, Yucatan (Mexico); Mendez-Gamboa, J.; Perez-Quintana, I.; Medina-Ezquivel, R. [Yucatan Autonomous University, Faculty of Engineering. AP 150 Cordemex, 97310, Merida, Yucatan (Mexico)

    2011-09-01

    CdS thin films were grown by fast evaporation technique combined with substrate rotation. The source evaporation temperature was maintained at 600 deg. C and the substrate temperature at 350 deg. C with background pressure of 1.0 m Torr. The substrates were corning glass 2947 with dimension of 1 in. x 1 in. rotate at 500 rpm during the growth. In order to verify the quality of the CdS films, the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical measurements. The films shown a flat uniformity thickness with growth rate of {approx}3.5 nm/s, the orientation was in the cubic-(1 1 1) and hexagonal-(0 0 2) plane in dependence of the growth time, grain size {approx}5 nm, roughness uniformity {approx}2.7 nm, transmittance in the visible region spectrum {approx}80%, energy band gap between 2.39 and 2.42 eV and short circuit photocurrent density (J{sub SC}) losses in the CdS films of 4.7 mA/cm{sup 2}.

  6. Tungsten oxide thin films grown by thermal evaporation with high resistance to leaching

    International Nuclear Information System (INIS)

    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 O16 (α,α')O16 resonant nuclear reaction. Films obtained at higher temperatures show well-defined spherical nanometric structure; they are composed of WO3.1 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. Electron-gun Evaporation of Cu and In thin Films as Precursors for CuInSe, Formation

    International Nuclear Information System (INIS)

    In the present invigorations CuInSe, is obtained in two stages: sequential evaporation of Cu and In using an electron gun evaporator on substrates up to 30 x 30 cm2, and a posterior selenization of the deposited films. The study is mainly focused on the first stage, in where the control of the different evaporation parameters of the metal precursors is essential. Electrical measurements are carried out, and also the topography and the thickness are determined with the object of studying the properties and homogeneity of the thin films. (Author) 19 refs

  8. Morphology, surface topography and optical studies on electron beam evaporated MgO thin films

    Indian Academy of Sciences (India)

    A Chowdhury; J Kumar

    2006-10-01

    Electron beam evaporated thin films of MgO powder synthesized by burning of magnesium ribbon in air and sol–gel technique are studied for their microstructure (SEM), surface topography (AFM), and optical transmission behaviour (UV-visible spectroscopy). MgO thin films are shown to be either continuous or have mesh like morphology. The bar regions are believed to be of magnesium hydroxide formed due to absorption of moisture. Their AFM images exhibit columnar/pyramidal/truncated cone structure, providing support to the 3D Stranski–Krastanov model for film growth. Further, they are shown to have high transmittance (∼90%) in the wavelength range 400–600 nm, but absorb radiation below 350 nm substantially giving signature of a band transition.

  9. Properties of CdTe films deposited by electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Murali, K.R.; Radhakrishna, I.; Nagaraja Rao, K.; Venkatesan, V.K. (Central Electrotechnical Research Inst., Karaikudi (India))

    1990-04-01

    Cadmium telluride thin films were prepared by electron beam evaporation on glass substrates kept at different temperatures in the range 30-300degC. The films were characterized by X-ray diffraction, scanning electron microscopy and optical absorption measurements. The conductivity of the films was measured in the temperature range 100-300 K. While the low temperature data (100-200 K) could be explained by the variable range hopping process, the high temperature data (200-300 K) could be explained on the basis of Seto's model for thermionic emission of the carriers over the grain boundaries. Transmission spectra have indicated a direct and gap around 1.55 eV. (orig.).

  10. Magnetic studies on ZnTe:Cr film grown on glass substrate by thermal evaporation method

    International Nuclear Information System (INIS)

    ZnTe and ZnTe:Cr films were prepared on glass substrate by using thermal evaporation method. X-ray diffraction analysis revealed the presence of ZnCrTe phase. X-ray photoelectron spectroscopy was used to estimate the composition of as-prepared films. The valence state of Cr in ZnTe:Cr film is determined to be +2 by using electron spin resonance spectroscopy. Magnetic moment data as a function of magnetic field was recorded by using superconducting quantum interference device magnetometry at 300 K. The result showed a clear hysteresis loop with coercive field of 48 Oe. Magnetic domains were observed by using magnetic force microscopy and the average value of domain size was 3.7 nm.

  11. Physical properties of ITO thin films prepared by ion-assisted electron beam evaporation

    Science.gov (United States)

    Qiu, Yang; Jin, Yangli; Zhao, Hua; Xu, Bo; Wang, Jiajia

    2014-12-01

    Tin doped indium oxide (ITO) thin films were prepared on IR glass substrates at different oxygen flow rate by ion-assisted electron beam evaporation method. Properties such as microstructure, morphology, sheet resistance and optical transmittance were investigated by X-ray diffractometer, SEM, four-point probe and UV-VIS-IR spectrophotometer, respectively. Lattice constant, inner stress level and energy band gap (Eg) of ITO thin films as-deposited were calculated and discussed. The mechanical properties of ITO thin films were studied by scratching method. The measurements were performed by scratch tester and the results were recorded as acoustic emission spectra and scratch track images taken by SEM. Relationship between inner stress level and mechanical performance was investigated in detail.

  12. Influence of multi-depositions on the final properties of thermally evaporated TlBr films

    International Nuclear Information System (INIS)

    Thallium bromide is a promising candidate material for photodetectors in medical imaging systems. This work investigates the structural, optical and electrical properties of thermally evaporated TlBr films. The main fabrication parameter is the number of depositions. The use of sequential runs is aimed to increase the thickness of the films, as necessary, for technological applications. We deposited films using one-four runs, that led to maximum thickness of about 50 μm. Crystallographic and morphological changes were observed with varying deposition runs. Nevertheless, the optical gap and electrical resistivity in the dark remained constant at about 2.85 eV and 109 Ω cm, respectively. Thicker samples have a larger ratio of photo-to-dark signal under medical X-ray exposure, with a larger linear region as a function of applied voltage. The results are discussed aiming at future technological applications in medical imaging.

  13. Pumping experiment of water on B and LaB6 films with electron beam evaporator

    International Nuclear Information System (INIS)

    Pumping characteristics of water vapor on boron and lanthanum hexaboride films formed with an electron beam evaporator have been investigated in high vacuum of a pressure region between 10-4 and 10-3 Pa. Measured initial maximum pumping speeds of water for fresh B and LaB6 films on substrates with a deposition amount from 2.3 x 1021 to 6.7 x 1021 molecules·m-2 are 3.2 ∼ 4.9 m3·s-1·m-2, and maximum saturation amounts of adsorbed water on these films are 2.9 x 1020 ∼ 1.3 x 1021 H2O molecules·m-2. (author)

  14. Visualization and minimization of clustering of micro-pillars and walls due to liquid film evaporation

    Science.gov (United States)

    Kim, Tae-Hong; Kim, Jungchul; Kim, Ho-Young

    2013-11-01

    The spin drying, in which a rinsing liquid deposited on a wafer is rapidly dried by wafer spinning, is an essential step in the semiconductor manufacturing process. While the liquid evaporates, its meniscus straddles neighboring submicron-size patterns such as pillars and walls. Then the capillary effects that pull the patterns together may lead to direct contact of the patterns, which is often referred to as pattern leaning. This poses a problem becoming more and more serious as the pattern size shrinks and the aspect ratio of the patterns increases. While the clustering behavior of high-aspect-ratio micro- and nanopillars was investigated before, a technical strategy to prevent such clustering has been pursed in industrial practices without being supported by the recently established theory of elastocapillarity. Here we visualize the clustering behavior of polymer micropatterns with the evaporation of liquid film while varying the sizes and temperature of the micropatterns. We find a critical role of substrate temperature in preventing the leaning of the patterns via changing the evaporation rate and behavior of the liquid film. Also, we construct a regime map that guides us to find a process condition to avoid pattern leaning in semiconductor manufacturing. This work was supported by the National Research Foundation of Korea (grant no. 2012-008023).

  15. Thin film phosphor materials for future display devices: rare earth doped thin film phosphor grown by reactive evaporation method

    International Nuclear Information System (INIS)

    A reactive evaporation system consisting of an electron-beam, a resistive heater, a lamp heater and a gas source was built. Transparent rare earth (RE) doped phosphor thin films have been grown using this system. RE metal were vaporized by electron-beam bombardment and were allowed to react with O2 gas to obtained oxide-based films and SO2 gas to obtain oxysulfide based films. RE dopant was simultaneously supplied from a resistive heated boat containing (RE)Cl3 powder. Photoluminescence together with XRD results show that the samples were crystallized and suggest that the RE3+ ions substitute the cations in the host lattices and form good luminescence centers. (Author)

  16. Photovoltaic structures using thermally evaporated SnS and CdS thin films

    International Nuclear Information System (INIS)

    Polycrystalline tin sulfide thin films were prepared by thermal evaporation technique. The films grown at substrate temperature of 300 °C had an orthorhombic crystal structure with strong preferred orientation along (111) plane. Electrical resistivity of the deposited films was about 32.5 Ω cm with a direct optical band gap of 1.33 eV. Carrier concentration and mobility of charge carriers estimated from the Hall measurement were found to be 6.24 × 1015 cm−3 and 30.7 cm2V−1 s−1 respectively. Heterojunction solar cells were fabricated in superstrate configuration using thermally evaporated SnS as an absorber layer and CdS, In:CdS as window layer. The resistivity of pure CdS thin film of a thickness of 320 nm was about 1–2 Ω cm and was reduced to 40 × 10−3 Ω cm upon indium doping. The fabricated solar cells were characterized using solar simulator. The solar cells with indium doped CdS window layer showed improved performance as compared to pure CdS window layer. The best device had a conversion efficiency of 0.4% and a fill factor of 33.5%. - Highlights: • Solar cells fabricated using SnS absorber and CdS, indium-doped CdS window layer • Resistivity of CdS film is 1–2 Ω cm and reduced to 40 × 10−3 Ω cm by In doping (1.5 at.%). • Optical band gap increased from 2.42 eV for pure CdS to 2.51 eV for In:CdS thin films. • Efficiency increased from 0.31% to 0.4% for solar cells with In:CdS window layer

  17. Intercalation studies on electron beam evaporated MoO{sub 3} films for electrochemical devices

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumar, R. [Department of Physics, Alagappa University, Karaikudi 630003 (India); Manisankar, P. [Deptartment of Industrial Chemistry, Alagappa University, Karaikudi 630003 (India); Jayachandran, M.; Sanjeeviraja, C. [ECMS Division, Central Electrochemical Research Institute, Karaikudi 630006 (India)

    2006-09-22

    Now-a-days a large number of extensive research has been focused on electrochromic oxide thin films, owing to their potential applications in smart windows, low cost materials in filters, low cost electrochemical devices and also in solar cell windows. Among the varieties of electrochromic transition metal oxides, the molybdenum oxide (MoO{sub 3}) and tungsten oxide (WO{sub 3}), form a group of predominant ionic solids that exhibit electrochromic effect. The electrochromic response of these materials are aesthetically superior to many other electrochromic materials, because WO{sub 3} and MoO{sub 3} absorb light more intensely and uniformly. In the present case, we have discussed about the electrochromic behaviour of electron beam evaporated MoO{sub 3} films. Moreover, the MoO{sub 3} film can also be used as a potential electro-active material for high energy density secondary lithium ion batteries; because it exhibits two-dimensional van der Waals bonded layered structure in orthorhombic phase. The films were prepared by evaporating the palletized MoO{sub 3} powder under the vacuum of the order of 1 x 10{sup -5}mbar. The electrochemical behaviour of the films was studied by intercalating/deintercalating the K{sup +} ions from KCl electrolyte solutions using three electrode electrochemical cell by the cyclic-voltammetry technique. The studies were carried out for different scanning rates. The films have changed their colour as dark blue in the colouration process and returns to the original colour while the bleaching process. The diffusion coefficient values (D) of the intercalated/deintercalated films were calculated by Randle's Servcik equation. The optical transparency of the coloured and bleached films was studied by the UV-Vis-NIR spectrophotometer. The change in bonding assignment of the intercalated MoO{sub 3} films was studied by FTIR spectroscopic analysis. A feasible study on the effect of substrate temperatures and annealing temperatures on optical

  18. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    International Nuclear Information System (INIS)

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of 4He adsorbed on metallic films. In contrast to measurements of 4He adsorbed on all other insulating substrates, we have shown that 4He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, 4He adsorbed on sapphire and on Ag films and H2 adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs

  19. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    Energy Technology Data Exchange (ETDEWEB)

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

  20. Synthesis, structural and electrochemical properties of electron beam evaporated V2O5 thin films

    International Nuclear Information System (INIS)

    Vanadium pentoxide is one of the most promising cathode materials because it offers high energy density, low cost, low toxicity over the other cathode materials. Its layered and open structure makes this material in thin film form well suited for electro-chemical insertion reactions with the Li ions. In the present investigation, V2O5 thin films have been prepared by electron beam evaporation technique on gold coated silicon substrates maintained at a substrate temperature of 250°C in an oxygen partial pressure of 2 × 10−4 mbar. The XRD patterns exhibited three predominant diffraction peaks corresponding to (200) (001) and (400) planes of orthorhombic phase of V2O5 with Pmnm space group. The electrochemical characteristics of V2O5 thin films with thickness of 600 nm were examined in non-aqueous region. The film exhibited step wise discharge with two plateaus. The as-deposited film delivered a discharge capacity of 70 μAh/(cm2-μm) at a current density of 30 μA/cm2. Annealing of these films at 450°C exhibited a better discharge capacity of 90 μAh/(cm2-μm).

  1. Synthesis, structural and electrochemical properties of electron beam evaporated V2O5 thin films

    Science.gov (United States)

    Hussain, O. M.; Rosaiah, P.

    2012-06-01

    Vanadium pentoxide is one of the most promising cathode materials because it offers high energy density, low cost, low toxicity over the other cathode materials. Its layered and open structure makes this material in thin film form well suited for electro-chemical insertion reactions with the Li ions. In the present investigation, V2O5 thin films have been prepared by electron beam evaporation technique on gold coated silicon substrates maintained at a substrate temperature of 250°C in an oxygen partial pressure of 2 × 10-4 mbar. The XRD patterns exhibited three predominant diffraction peaks corresponding to (200) (001) and (400) planes of orthorhombic phase of V2O5 with Pmnm space group. The electrochemical characteristics of V2O5 thin films with thickness of 600 nm were examined in non-aqueous region. The film exhibited step wise discharge with two plateaus. The as-deposited film delivered a discharge capacity of 70 μAh/(cm2-μm) at a current density of 30 μA/cm2. Annealing of these films at 450°C exhibited a better discharge capacity of 90 μAh/(cm2-μm).

  2. Characteristics of electron beam evaporated nanocrystalline SnO2 thin films annealed in air

    International Nuclear Information System (INIS)

    Tin oxide (SnO2) thin films (about 200 nm thick) have been deposited by electron beam evaporation followed by annealing in air at 350-550 deg. C for two hours. Optical, electrical and structural properties were studied as a function of annealing temperature. The as-deposited film is amorphous, while all other annealed films are crystalline (having tetragonal structure). XRD suggest that the films are composed of nanoparticles of 5-10 nm. Raman analysis and optical measurements suggest quantum confinement effects that are enhanced with annealing temperature. For instance, Raman peaks of the as-deposited films are blue-shifted as compared to those for bulk SnO2. Blue shift becomes more pronounced with annealing temperature. Optical band gap energy of amorphous SnO2 film is 3.61 eV, which increases to about 4.22 eV after crystallization. Two orders of magnitude decrease in resistivity is observed after annealing at 350-400 deg. C due to structural ordering and crystallization. The resistivity, however, increases slightly with annealing temperature above 400 deg. C, possibly due to improvement in stoichiometry and associated decrease in charge carrier density.

  3. Annealing effect for SnS thin films prepared by high-vacuum evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Revathi, Naidu, E-mail: revathi.naidu@ttu.ee; Bereznev, Sergei; Loorits, Mihkel; Raudoja, Jaan; Lehner, Julia; Gurevits, Jelena; Traksmaa, Rainer; Mikli, Valdek; Mellikov, Enn; Volobujeva, Olga [Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086 (Estonia)

    2014-11-01

    Thin films of SnS are deposited onto molybdenum-coated soda lime glass substrates using the high-vacuum evaporation technique at a substrate temperature of 300 °C. The as-deposited SnS layers are then annealed in three different media: (1) H{sub 2}S, (2) argon, and (3) vacuum, for different periods and temperatures to study the changes in the microstructural properties of the layers and to prepare single-phase SnS photoabsorber films. It is found that annealing the layers in H{sub 2}S at 400 °C changes the stoichiometry of the as-deposited SnS films and leads to the formation of a dominant SnS{sub 2} phase. Annealing in an argon atmosphere for 1 h, however, causes no deviations in the composition of the SnS films, though the surface morphology of the annealed SnS layers changes significantly as a result of a 2 h annealing process. The crystalline structure, surface morphology, and photosensitivity of the as-deposited SnS films improves significantly as the result of annealing in vacuum, and the vacuum-annealed films are found to exhibit promising properties for fabricating complete solar cells based on these single-phase SnS photoabsorber layers.

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

    International Nuclear Information System (INIS)

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

  5. Thermoelectric power of CdTe thin films prepared by vacuum evaporation method

    International Nuclear Information System (INIS)

    Cadmium Telluride (CdTe) thin films of different thickness have been prepared by vacuum evaporation method on glass substrate at room temperature. X-ray diffraction and thermoelectric power (TEP) measurements were carried out on these films. The XRD pattern shows that as-deposited films are amorphous in character. Thermoelectric power (TEP) measured from room temperature to 450 K and it shows positive value at room temperature and decreases with the increase of temperature up to T approx. 314 K, above which it remains almost constant. At higher temperature, T > 410 K, TEP becomes negative. These experimental results reveal that there are two types of carriers present in as-deposited films. In low temperature region, dominant carriers are holes and at high temperature (T > 410 K) it is electron. The activation energy E0 and temperature coefficient of activation energy g have been calculated from TEP data. E0 and g varies with film thickness and their values range from 0.52 to 1.21 eV and 7.05x10-4 to 18.4x10-4 eV K-1 respectively. It is found that TEP does not vary systematically with film thickness, which is one of the characteristics of amorphous materials reported in the text. (author)

  6. Concentration of Melton Valley Storage Tank surrogates with a wiped film evaporator

    International Nuclear Information System (INIS)

    This report describes experiments to determine whether a wiped film evaporator (WFE) might be used to concentrate low-level liquid radioactive waste (LLLW). Solutions used in these studies were surrogates that contain no radionuclides. The compositions of the surrogates were based on one of Oak Ridge National Laboratory's (ORNL's) Melton Valley Storage Tanks (MVSTs). It was found that a WFE could be used to concentrate LLLW to varying degrees by manipulating various parameters. The parameters studied were rotor speed, process fluid feed temperature and feed rate, and evaporator temperature. Product consistency varied from an unsaturated liquid to a dry powder. Volume reductions up to 68% were achieved. System decontamination factors were consistently in the range of 104

  7. Simple evaporation controller for thin-film deposition from a resistively heated boat

    Science.gov (United States)

    Scofield, John H.; Bajuk, Lou; Mohler, William

    1990-01-01

    A simple, inexpensive circuit is described for switching the current through a resistively heated evaporation boat during thin-film deposition. The circuit uses a silicon-controlled rectifier (SCR) to switch the 0-15-A current in the primary of a 2-kV A step-down transformer that supplies the 0-200-A current to an evaporation boat. The circuit is controlled by a 0-10 V-dc signal similar to that furnished by an Inficon XTC deposition-rate controller. This circuit may be assembled from a handful of parts for a cost of about $400, nearly one-tenth the cost of similar commercial units. Minimum construction is required, since the circuit is built around an off-the-shelf, self-contained SCR unit.

  8. Experimental study of evaporation of horizontal films of water–salt solutions

    Directory of Open Access Journals (Sweden)

    Elistratov S.L.

    2015-01-01

    Full Text Available The present studies were carried out for the horizontal films (thin layers of water and water solutions of NaCl, CaCl2, LiCl, and LiBr with different solubility characteristics, as well as with specific features of formation and decay of water hydrates. Required volume of solution Vo of given weight concentration ξo, preliminary heated to the working surface temperature, was put in one step on the horizontal bottom of the bowl, heated to working temperature tCT, by means of volume batchers Thermo Scientific. After evaporation completion, the final mass of solution and form of their residue were registered. At the final stage of evaporation formation of NaCl crystals and water hydrates of CaCl2 · 2H2O, LiCl · H2O, and LiBr · 2H2O occurred.

  9. Electronic Emition Properties of Bi Layer Novel Organic Semiconductor Systems

    OpenAIRE

    Salazar-Valencia, P. J.; Bolivar-Marinez, L. E.; Perez-Merchancano, S. T.

    2007-01-01

    The perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA) and 1,4,5,8-naphthalene-tetracaboxylic-dianhydride (NTCDA) are planar pi-stacking organic molecules that have been shown to be excellent model compounds for studying the growth and optoelectronic properties of organic semiconductor thin films, particularly organic diodes. Some observations have shown that this molecules, particularly PTCDA a brick-like shaped molecule easily forms well-ordered films on various substrates due to its uni...

  10. Characterization of thermally evaporated lead iodide films aimed for the detection of X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Caldeira Filho, A.M. [Departamento de Fisica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo - USP, Avenida Bandeirantes 3900, 14040-901, Ribeirao Preto-SP (Brazil); Mulato, M., E-mail: mmulato@ffclrp.usp.b [Departamento de Fisica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo - USP, Avenida Bandeirantes 3900, 14040-901, Ribeirao Preto-SP (Brazil)

    2011-04-21

    Some semiconductor materials such as lead iodide (PbI{sub 2}) have applications in the detection of ionizing radiation at room temperature using the direct detection method. In this work we investigate lead iodide films deposited by thermal evaporation. The morphology, structure, and electric properties were investigated as a function of deposition height, i.e. the distance between evaporation-boat and substrates. The results show a morphology of vertical leaves and X-ray diffraction shows just one preferential orientation along the direction 110. Energy dispersive spectroscopy reveals that the films are not stoichiometric, with excess iodine atoms. Electrical resistivity of about 10{sup 8} {Omega} cm was measured. This is smaller than for the bulk due to structural defects. The values of activation energy for electric transport increase from 0.52 up to 1.1 eV with decreasing deposition height, what indicates that the best film is the one deposited at the shortest distance. Exposure under X-ray mammographic energy shows a linear behavior up to 500 mR. No variation in sensibility was observed between 22 and 30 kVp.

  11. Characterization of thermally evaporated lead iodide films aimed for the detection of X-rays

    International Nuclear Information System (INIS)

    Some semiconductor materials such as lead iodide (PbI2) have applications in the detection of ionizing radiation at room temperature using the direct detection method. In this work we investigate lead iodide films deposited by thermal evaporation. The morphology, structure, and electric properties were investigated as a function of deposition height, i.e. the distance between evaporation-boat and substrates. The results show a morphology of vertical leaves and X-ray diffraction shows just one preferential orientation along the direction 110. Energy dispersive spectroscopy reveals that the films are not stoichiometric, with excess iodine atoms. Electrical resistivity of about 108 Ω cm was measured. This is smaller than for the bulk due to structural defects. The values of activation energy for electric transport increase from 0.52 up to 1.1 eV with decreasing deposition height, what indicates that the best film is the one deposited at the shortest distance. Exposure under X-ray mammographic energy shows a linear behavior up to 500 mR. No variation in sensibility was observed between 22 and 30 kVp.

  12. Physical properties of electron beam evaporated CdTe and CdTe:Cu thin films

    International Nuclear Information System (INIS)

    In this paper, we report on physical properties of pure and Cu doped cadmium telluride (CdTe) films deposited onto corning 7059 microscopic glass substrates by electron beam evaporation technique. X-ray diffraction study showed that all the deposited films belong to amorphous nature. The average transmittance of the films is varied between 77% and 90%. The optical energy band gap of pure CdTe film is 1.57 eV and it decreased to 1.47 eV upon 4 wt. % of Cu addition, which may be due to the extension of localized states in the band structure. The refractive index of the films was calculated using Swanepoel method. It was observed that the dispersion data obeyed the single oscillator of the Wemple-Didomenico model, from which the dispersion energy (Ed) parameters, dielectric constants, plasma frequency, and oscillator energy (Eo) of CdTe and CdTe:Cu films were calculated and discussed in detail with the light of possible mechanisms underlying the phenomena. The variation in intensity of photoluminescence band edge emission peak observed at 820 nm with Cu dopant is due to the change in surface state density. The observed trigonal lattice of Te peaks in the micro-Raman spectra confirms the p-type conductive nature of films, which was further corroborated by the Hall effect measurement. The lowest resistivity of 6.61 × 104 Ω cm was obtained for the CdTe:Cu (3 wt. %) film

  13. Film-Evaporation MEMS Tunable Array for Picosat Propulsion and Thermal Control

    Science.gov (United States)

    Alexeenko, Alina; Cardiff, Eric; Martinez, Andres; Petro, Andrew

    2015-01-01

    The Film-Evaporation MEMS Tunable Array (FEMTA) concept for propulsion and thermal control of picosats exploits microscale surface tension effect in conjunction with temperature- dependent vapor pressure to realize compact, tunable and low-power thermal valving system. The FEMTA is intended to be a self-contained propulsion unit requiring only a low-voltage DC power source to operate. The microfabricated thermal valving and very-high-integration level enables fast high-capacity cooling and high-resolution, low-power micropropulsion for picosats that is superior to existing smallsat micropropulsion and thermal management alternatives.

  14. Transparent conductive indium oxide film deposited on low temperature substrates by activated reactive evaporation.

    Science.gov (United States)

    Marcovitch, O; Klein, Z; Lubezky, I

    1989-07-15

    High quality conductive coatings for the visible region were prepared on low temperature glass substrates. The conductive layer was an indium oxide film deposited by the activated reactive evaporation technique using a glow discharge hollow cathode ion gun. An antireflective layer of MgF(2) was deposited over the conductive layer. The average transmission in the visible region of the coated glass with sheet resistance of coating was durable and passed a series of environmental tests according to MIL-C-675C. PMID:20555600

  15. Transparent conductive indium oxide film deposited on low temperature substrates by activated reactive evaporation

    International Nuclear Information System (INIS)

    High quality conductive coatings for the visible region were prepared on low temperature glass substrates. The conductive layer was an indium oxide film deposited by the activated reactive evaporation technique using a glow discharge hollow cathode ion gun. An antireflective layer of MgFz was deposited over the conductive layer. The average transmission in the visible region of the coated glass with sheet resistance of 15 Ω/sq was greater than 90%. The coating was durable and passed a series of environmental tests according to MIL-C-675C

  16. Effect of porous polymer films (track membranes) on the isothermal evaporation kinetics of water

    Science.gov (United States)

    Novikov, S. N.; Ermolaeva, A. I.; Timoshenkov, S. P.; Korobova, N. E.; Goryunova, E. P.

    2016-06-01

    The kinetics of isothermal evaporation of distilled water that was in remote (10-15-mm) contact with porous polymer films (track membranes (TMs)) was studied by microgravimetry (derivatograph). When the H2O-TM system contained a disperse medium, the supramolecular structure of water changed, and the number of clusters (coherent domains) drastically decreased. The extraction of the light phase from liquid water was correlated with the chemisorption of H2O molecules containing the para-isomer of hydrogen, which predominantly form coherent domains of water.

  17. Controlled delivery achieved with bi-layer matrix devices produced by co-injection moulding

    OpenAIRE

    Vaz, Cláudia M.; Doeveren, P. F. N. M. van; Dias, Gustavo R.; R.L. Reis; Cunha, A.M.

    2004-01-01

    The aim of this study was to design new soy protein-based bi-layered co-injection moulded matrix systems aimed to achieve controlled drug delivery. The devices consisted of a drug-free outer layer (skin) and a drug-containing core. The systems overcame the inherent disadvantage of non-linear release associated with diffusion-controlled single-layer matrix devices by providing additional releasing area with time to compensate for the decreasing release rate. As expected, the bi-layer devices p...

  18. Prevention of Intra-Abdominal Adhesion by Bi-Layer Electrospun Membrane

    OpenAIRE

    Cunyi Fan; Hede Yan; Wei Wang; Shichao Jiang

    2013-01-01

    The aim of this study was to compare the anti-adhesion efficacy of a bi-layer electrospun fibrous membrane consisting of hyaluronic acid-loaded poly(ε-caprolactone) (PCL) fibrous membrane as the inner layer and PCL fibrous membrane as the outer layer with a single-layer PCL electrospun fibrous membrane in a rat cecum abrasion model. The rat model utilized a cecal abrasion and abdominal wall insult surgical protocol. The bi-layer and PCL membranes were applied between the cecum and the abdomin...

  19. Deposition of TiN, TiC, and TiO2 films by filtered arc evaporation

    International Nuclear Information System (INIS)

    A filtered arc deposition process was used in the reactive deposition of macroparticle-free TiO2, TiN, and TiC films. The TiO2 films were reactively deposited by arc evaporation of titanium in an oxygen atmosphere. The films deposited onto glass substrates heated to 350degC had a rutile structure and a refractive index n633 of 2.735 and extinction coefficient k633 of 0.07. Films of TiN and TiC were prepared by reactive evaporation in nitrogen and methane respectively. The lattice parameters and preferred orientations of the deposited films were measured as a function of negative substrate bias. The films were characterized by microhardness measurements, X-ray photoelectron spectroscopy and X-ray diffraction. (orig.)

  20. Improved stoichiometry and photoanode efficiency of thermally evaporated CdS film with quantum dots as precursor

    Science.gov (United States)

    Fan, Libo; Wang, Peng; Guo, Qiuquan; Lei, Yan; Li, Ming; Han, Hongpei; Zhao, Haifeng; Yang, Dongluo; Zheng, Zhi; Yang, Jun

    2015-08-01

    Good stoichiometry of cadmium sulfide (CdS) film facilitates its application in photovoltaic devices; however, traditional thermal evaporation usually results in a Cd-deficient CdS film at a low-substrate temperature. In this study, Cd-rich CdS quantum dots (QDs) were synthesized by a facile co-precipitation method and used as the precursor to thermally evaporate CdS film on indium tin oxide-coated glass (ITO/glass). As a consequence, the stoichiometry of CdS film was greatly improved with atomic ratio of Cd to S restored to unity. More importantly, the newly developed CdS film, with its rod-like surface microstructure, acted as an efficient photoanode in a photoelectrochemical (PEC) cell. Its properties, including surface morphology and roughness, crystal structure, chemical composition, film thickness, energy-level structure and photosensitivity, are studied in detail.

  1. Biaxial stresses, surface roughness and microstructure in evaporated TiO2 films with different deposition geometries

    International Nuclear Information System (INIS)

    The residual stresses, surface roughness and microstructure in titanium oxide films prepared by electron-beam evaporation and deposited with different geometries were investigated, with particular focus on the in-plane anisotropy of the biaxial stresses and microstructures. Thin films were deposited with various deposition angles on B270 glass substrates and silicon wafers. Two different types of deposition geometries were studied. The residual stress in the thin films was examined by a phase-shifting Twyman-Green interferometer. The optical constants, biaxial stress and surface roughness were found to be related to the evolution of the anisotropic microstructures in the films. The results revealed that the anisotropic stresses that developed in the evaporated titanium oxide films were dependent upon the deposition geometry and microstructure of the films.

  2. Physical properties of Sb-doped CdSe thin films by thermal evaporation method

    International Nuclear Information System (INIS)

    Cadmium selenide (CdSe) thin films were deposited on the glass substrates by using the resistive thermal evaporation method in the vacuum chamber. The effect of antimony doping on the physical properties of CdSe thin film has been investigated. The structural and surface properties such as lattice parameters, grain size, microstrain and dislocation density of the thin films were characterized by X-ray diffraction (XRD) technique. The compositional properties were studied by the mean of Rutherford backscattering (RBS) and UV–Vis–NIR spectrophotometer used to determine the refractive index, absorption coefficient and optical energy band gap of thin films. The FTIR absorption spectra confirmed the presence of CdSe vibrational mode in the range 400 cm−1 to 700 cm−1. The electrical conductivity of the films was carried out with the help of impedance analyzer, which has been increased up to 1% on Sb doping. The transmission has been reduced up to 18% with the increase in Sb doping and shifted toward lower wavelengths.

  3. Photoelectric properties of Cu2ZnSnS4 thin films deposited by thermal evaporation

    Institute of Scientific and Technical Information of China (English)

    吴新坤; 柳伟; 程树英; 赖云锋; 贾宏杰

    2012-01-01

    Sn/Cu/ZnS precursor were deposited by evaporation on soda lime glass at room temperature,and then polycrystalline thin films of Cu2ZnSnS4 (CZTS) were produced by sulfurizing the precursors in a sulfur atmosphere at a temperature of 550 ℃ for 3 h.Fabricated CZTS thin films were characterized by X-ray diffraction,energy dispersive X-ray spectroscopy,ultraviolet-visible-near infrared spectrophotometry,the Hall effect system,and 3D optical microscopy.The experimental results show that,when the ratios of [Cu]/([Zn] + [Sn]) and [Zn]/[Sn] in the CZTS are 0.83 and 1.15,the CZTS thin films possess an absorption coefficient of larger than 4.0 × 104 cm-1 in the energy range 1.5-3.5 eV,and a direct band gap of about 1.47 eV.The carrier concentration,resistivity and mobility of the CZTS film are 6.98 × 1016 cm-3,6.96 Ω.cm,and 12.9 cm2/(V.s),respectively and the conduction type is p-type.Therefore,the CZTS thin films are suitable for absorption layers of solar cells.

  4. Characterization of activated reactive evaporated MoO3 thin films for gas sensor applications

    International Nuclear Information System (INIS)

    Thin films of molybdenum trioxide (MoO3) were prepared by activated reactive evaporation technique on Pyrex glass substrates. The influence of oxygen partial pressure, substrate temperature and glow power on the structure, surface morphology and optical properties of MoO3 thin films was studied. The MoO3 films deposited in an oxygen partial pressure of 1x10-3 Torr, glow power of 10 W and substrate temperature of 573 K exhibited predominantly a (0 k 0) orientation corresponding to the orthorhombic layered structure of α-MoO3. The evaluated optical band gap was 3.24 eV. The sensing property of these MoO3 films for gases like NH3 and CO was also studied to see the applicability for environmental monitoring. We have observed that the MoO3 thin films of α-phase are capable of detecting NH3 and CO gases at concentrations lower than 10 ppm in dry air

  5. Physical properties of Sb-doped CdSe thin films by thermal evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Mazhar [Department of Physics, International Islamic University Islamabad, Islamabad 45320 (Pakistan); Syed, Waqar A.A., E-mail: adil.syed@iiu.edu.pk [Department of Physics, International Islamic University Islamabad, Islamabad 45320 (Pakistan); Zubair, M. [Department of Physics, International Islamic University Islamabad, Islamabad 45320 (Pakistan); Shah, Nazar A. [Department of Physics, COMSATS Institute of Information Technology, Islamabad 4000 (Pakistan); Mehmood, Arshad [NILOP, P.O. Nilore, Islamabad 45320 (Pakistan)

    2013-11-01

    Cadmium selenide (CdSe) thin films were deposited on the glass substrates by using the resistive thermal evaporation method in the vacuum chamber. The effect of antimony doping on the physical properties of CdSe thin film has been investigated. The structural and surface properties such as lattice parameters, grain size, microstrain and dislocation density of the thin films were characterized by X-ray diffraction (XRD) technique. The compositional properties were studied by the mean of Rutherford backscattering (RBS) and UV–Vis–NIR spectrophotometer used to determine the refractive index, absorption coefficient and optical energy band gap of thin films. The FTIR absorption spectra confirmed the presence of CdSe vibrational mode in the range 400 cm{sup −1} to 700 cm{sup −1}. The electrical conductivity of the films was carried out with the help of impedance analyzer, which has been increased up to 1% on Sb doping. The transmission has been reduced up to 18% with the increase in Sb doping and shifted toward lower wavelengths.

  6. Structural and optical properties of electron beam evaporated CdSe thin films

    Indian Academy of Sciences (India)

    N J Suthan Kissinger; M Jayachandran; K Perumal; C Sanjeevi Raja

    2007-12-01

    Thin films of cadmium selenide (CdSe) as a semiconductor is well suited for opto-electronic applications such as photo detection or solar energy conversion, due to its optical and electrical properties, as well as its good chemical and mechanical stability. In order to explore the possibility of using this in optoelectronics, a preliminary and thorough study of optical and structural properties of the host material is an important step. Based on the above view, the structural and optical properties of CdSe films have been studied thoroughly in the present work. The host material, CdSe film, has been prepared by the physical vapour deposition method of electron beam evaporation (PVD: EBE) technique under a pressure of 5 × 10-5 mbar. The structural properties have been studied by XRD technique. The hexagonal structure with a preferred orientation along the (0 0 2) direction of films has been confirmed by the X-ray diffraction analysis. The films have been analysed for optical band gap and absorbed a direct intrinsic band gap of 1.92 eV.

  7. Sol–Gel and Thermally Evaporated Nanostructured Thin ZnO Films for Photocatalytic Degradation of Trichlorophenol

    Directory of Open Access Journals (Sweden)

    Mahmoud Sawsan

    2009-01-01

    Full Text Available Abstract In the present work, thermal evaporation and sol–gel coating techniques were applied to fabricate nanostructured thin ZnO films. The phase structure and surface morphology of the obtained films were investigated by X-ray diffractometer (XRD and scanning electron microscope (SEM, respectively. The topography and 2D profile of the thin ZnO films prepared by both techniques were studied by optical profiler. The results revealed that the thermally evaporated thin film has a comparatively smoother surface of hexagonal wurtzite structure with grain size 12 nm and 51 m2/g. On the other hand, sol–gel films exhibited rough surface with a strong preferred orientation of 25 nm grain size and 27 m2/g surface area. Following deposition process, the obtained films were applied for the photodegradation of 2,4,6-trichlorophenol (TCP in water in presence of UV irradiation. The concentrations of TCP and its intermediates produced in the solution during the photodegradation were determined by high performance liquid chromatography (HPLC at defined irradiation times. Complete decay of TCP and its intermediates was observed after 60 min when the thermal evaporated photocatalyst was applied. However, by operating sol–gel catalyst, the concentration of intermediates initially increased and then remained constant with irradiation time. Although the degradation of TCP followed first-order kinetic for both catalysts, higher photocatalytic activity was exhibited by the thermally evaporated ZnO thin film in comparison with sol–gel one.

  8. Preparation of Indium Tin Oxide films deposited by reactive evaporation at different substrate-temperature and the properties

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Indium Tin Oxide films have been prepared at different substrate-temperature on glass substrates by reactive evaporation of In-Sn alloy with an oxygen pressure of 1.3 × 10-1 Pa and a deposition rate of 10-2 nm/s. The best ITO films obtained cm2v-1s-1. The influence of the substrate-temperature on the structural, optical and electrical properties of the obtained films has been investigated.

  9. Structural, compositional and morphological studies of thermally evaporated MoO3 thin films

    International Nuclear Information System (INIS)

    Molybdenum oxide (MoO3) nanostructures were grown on different substrates such as glass, indium tin oxide coated glass and fluorine doped glass by thermal evaporation of MoO3 powder at elevated temperature (750°C) using tube furnace without any catalyst and then by subsequent O2/Ar flow rate. The morphology, composition and crystal structure were examined by using SEM, EDAX, Laser Raman and XRD. The films are polycrystalline with well-defined diffraction peaks and it consist of MoO3 with α-orthorhombic structure. The synthesized MoO3 belongs to different morphologies, generally nanobelt and nanohunk structures. The EDAX spectra confirm the films are composed only of Mo and O atoms. The O/Mo ratio is nearly equal to 3 that shows the stoichiometry of MoO3

  10. Growth of thin films of low molecular weight proteins by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Matei, Andreea; Schou, Jørgen; Constantinescu, C.;

    2011-01-01

    Thin films of lysozyme and myoglobin grown by matrix assisted pulsed laser evaporation (MAPLE) from a water ice matrix have been investigated. The deposition rate of these two low molecular weight proteins (lysozyme: 14307 amu and myoglobin: 17083 amu) exhibits a maximum of about 1–2 ng/cm2 per...... pulse at a fluence of 1–2 J/cm2 and decreases slowly with increasing fluence. This rate is presumably determined by the matrix rather by the proteins. A significant fraction of the proteins are intact in the film as determined by MALDI (Matrix assisted laser desorption ionization) spectrometry. The...... results for lysozyme demonstrate that the fragmentation rate of the proteins during the MAPLE process is not influenced by the pH of the water solution prior to freezing....

  11. Growth of epitaxial pyrite (FeS2) thin films using sequential evaporation

    International Nuclear Information System (INIS)

    Pyrite (FeS2), a semiconductor composed of inexpensive, non-toxic elements, has a band gap of ∼0.95 eV and an absorption coefficient higher than conventional direct band gap semiconductors, including GaAs. These facts have inspired the use of pyrite as a potential candidate for terawatt-scale photovoltaic systems. However, there has been limited progress synthesizing thin films of sufficient quality to produce efficient solar cells. Here we describe the layer-by-layer growth of stoichiometric, single-phase pyrite thin films on heated substrates using sequential evaporation of Fe under high vacuum followed by sulfidation at pressures ranging from 1 mTorr to 1 Torr. High-resolution transmission electron microscopy reveals high-quality, defect-free pyrite grains. We demonstrate that epitaxial pyrite layers can be deposited with this method on natural pyrite substrates

  12. Study of transport properties co - evaporated lead telluride (PbTe) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khairnar, U.P.; Bhavsar, G.P. [Thin film laboratory, Physics Department Pratap College, Amalner (India); Pawar, P.H. [Department of Electronics, Jai-Hind College, Dhule (India)

    2002-07-01

    Thin films of lead telluride (PbTe) of thicknesses ranging from 1000 A to 2500 A have been prepared by co-evaporation (three temperature) technique, onto precleaned amorphous glass substrates at various temperatures. The deposited samples were annealed and annealed samples were used for characterization. Resistivity of these samples was measured by four-probe technique as a function of thickness and temperature. Activation energy for charge transport have been evaluated and found in the range of 0.09 to 0.106 eV. Thermoelectric power has been measured and found to be positive indicating that the samples are p-type semiconducting material. Mobility variation with temperature has been estimated (evaluated) and correlated with scattering mechanism in the entire range of temperature studied. The X-ray diffraction analysis confirmed that films are polycrystalline having cubic structure cell and lattice parameters are reported. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  13. The anomalous low temperature resistivity of thermally evaporated alpha-Mn thin film

    Energy Technology Data Exchange (ETDEWEB)

    Ampong, F.K., E-mail: kampxx@yahoo.co [Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana); Boakye, F.; Nkum, R.K. [Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana)

    2010-08-15

    Electrical resistivity measurements have been carried out on thermally evaporated alpha-Mn thin film between 300 and 1.4 K using the van der Pauw four probe technique. The film was grown on a glass substrate held at a temperature of 373 K, in an ambient pressure of 5x10{sup -6} Torr. The results show a resistance minimum, a notable characteristic of alpha-Mn but at a (rather high) temperature of 194+-1 K. Below the resistivity maximum which corresponds to 70 K, the resistivity drops by only 0.02 muOMEGAm indicating a rather short range magnetic ordering. The low temperature results show a tendency towards saturation of the resistivity as the temperature approaches zero suggesting a Kondo scattering.

  14. Vapor-crystal phase transition in synthesis of paracetamol films by vacuum evaporation and condensation

    Science.gov (United States)

    Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.; Zarembo, V. I.

    2014-03-01

    We report on the structural and technological investigations of the vapor-crystal phase transition during synthesis of paracetamol films of the monoclinic system by vacuum evaporation and condensation in the temperature range 220-320 K. The complex nature of the transformation accompanied by the formation of a gel-like phase is revealed. The results are interpreted using a model according to which the vapor-crystal phase transition is not a simple first-order phase transition, but is a nonlinear superposition of two phase transitions: a first-order transition with a change in density and a second-order phase transition with a change in ordering. Micrographs of the surface of the films are obtained at different phases of formation.

  15. Functionalized porphyrin conjugate thin films deposited by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Iordache, S. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Popescu, A.C.; Popescu, C.E.; Dorcioman, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Ciucu, A.A. [University of Bucharest, Faculty of Chemistry, Bucharest (Romania); Balan, A.; Stamatin, I. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Fagadar-Cosma, E. [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazul Ave. 24, 300223-Timisoara (Romania); Chrisey, D.B. [Tulane University, Departments of Physics and Biomedical Engineering, New Orleans, LA 70118 (United States)

    2013-08-01

    We report on the deposition of nanostructured porphyrin-base, 5(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin thin films by matrix assisted pulsed laser evaporation onto silicon substrates with screen-printed electrodes. AFM investigations have shown that at 400 mJ/cm{sup 2} fluence a topographical transition takes place from the platelet-like stacking porphyrin-based nanostructures in a perpendicular arrangement to a quasi-parallel one both relative to the substrate surface. Raman spectroscopy has shown that the chemical structure of the deposited thin films is preserved for fluences within the range of 200–300 mJ/cm{sup 2}. Cyclic voltammograms have demonstrated that the free porphyrin is appropriate as a single mediator for glucose in a specific case of screen-printed electrodes, suggesting potential for designing a new class of biosensors.

  16. Structural and optical properties of Zn–In–Te thin films deposited by thermal evaporation technique

    International Nuclear Information System (INIS)

    Highlights: •The new ternary compound Zn–In–Te (ZIT) has been studied for photovoltaic device applications as an absorber layer. •ZIT thin films were deposited by thermal evaporation of stoichiometric sintered polycrystalline powder. •The optical constants were calculated by using different methods, (SOM), Envelope Model (EM) and Cauchy Method. •Urbach energies were calculated and the increasing band tail energies were observed with increasing annealing temperature. -- Abstract: Annealing effects on structural and optical properties of the thermally evaporated Zn–In–Te (ZIT) thin films have been investigated. The structural and the compositional analyses were carried out by means of X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDXA). The as-grown and annealed ZIT films had polycrystalline structure and the preferred orientation changed from (2 2 0) to (1 1 2) direction with increasing annealing temperature. The optical properties and constants were determined by transmittance measurements in the wavelength range of 200–2000 nm. The effect of annealing on the optical parameters was determined by using Single Oscillator Model (SOM), Envelope Model (EM) and Cauchy Method. The absorbance studies revealed that the films had three distinct transitions in the high absorption region because of the tetragonal distortion, and that was used to evaluate the splitting energies of crystal-field and spin–orbit splitting. The fundamental optical band gap values were found to be lying in the range of 1.51 and 1.72 eV and the notable change of the band gaps due to annealing temperatures was observed. Finally, the Urbach energies were calculated and it was observed that the band tail energies were increasing with increasing annealing temperature

  17. Structure and magnetic properties of Fe doped In2O3 thin films prepared by electron beam evaporation

    International Nuclear Information System (INIS)

    Pure and Fe (7 at.%) doped In2O3 thin films were grown onto the glass substrates by electron beam evaporation technique. The structural and magnetic properties of the pure and Fe doped In2O3 thin films have been studied. The undoped and Fe doped In2O3 thin films shown ferromagnetic property at room temperature. A magnetization of 24 emu/cm3 was observed for pure In2O3 thin films. The magnetization of 38.23 emu/cm3 was observed for the Fe (7 at.%) doped In2O3 thin films

  18. Influence of deposition rate on the properties of ZrO2 thin films prepared in electron beam evaporation method

    Institute of Scientific and Technical Information of China (English)

    Dongping Zhang(张东平); Meiqiong Zhan(占美琼); Ming Fang(方明); Hongbo He(贺洪波); Jianda Shao(邵建达); Zhengxiu Fan(范正修)

    2004-01-01

    ZrO2 thin films were prepared in electron beam thermal evaporation method. And the deposition rate changed from 1.3 to 6.3 nm/s in our study. X-ray diffractometer and spectrophotometer were employed to characterize the films. X-ray diffraction (XRD) spectra pattern shows that films structure changed from amorphous to polycrystalline with deposition rate increasing. The results indicate that internal stresses of the films are compressive in most case. Thin films deposited in our study are inhomogeneous, and the inhomogeneity is enhanced with the deposition rate increasing.

  19. Modeling of thin film explosive boiling—surface evaporation and electron thermal conductivity effect

    International Nuclear Information System (INIS)

    Phase transition in a thin liquid Al film during its rapid (sub) nanosecond homogeneous heating is studied in the framework of molecular dynamics simulation with electron thermal conductivity. The results are compared with our previous results without consideration of electron thermal conductivity. Surface evaporation leads to surface cooling and this effect is more pronounced at lower heating rates in the case without electron thermal conductivity. For the case with electron thermal conductivity, the obtained results suggest the existence of four different regimes of film behavior depending on the heating rate: quasi-stationary surface evaporation regime with relatively small fluctuations at the low heating rates, explosive (volume) boiling which is initiated as growth of a single fluctuation, spinodal decomposition with many fluctuations growing simultaneously and supercritical fluid expansion with no pronounced fluctuations at the high heating rates. Our calculations also show that the duration and magnitude of the explosive boiling pressure pulse, which occurs at the threshold heating rate, are about 0.3 ns and one third of the critical pressure value, respectively. Information of this kind is needed to determine the optimal conditions for the measurement of the critical parameters of different materials in laser ablation experiments. (paper)

  20. Evaporation characteristics of thin film liquid argon in nano-scale confinement: A molecular dynamics study

    Science.gov (United States)

    Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

    2016-07-01

    Molecular dynamics simulation has been carried out to explore the evaporation characteristics of thin liquid argon film in nano-scale confinement. The present study has been conducted to realize the nano-scale physics of simultaneous evaporation and condensation inside a confined space for a three phase system with particular emphasis on the effect of surface wetting conditions. The simulation domain consisted of two parallel platinum plates; one at the top and another at the bottom. The fluid comprised of liquid argon film at the bottom plate and vapor argon in between liquid argon and upper plate of the domain. Considering hydrophilic and hydrophobic nature of top and bottom surfaces, two different cases have been investigated: (i) Case A: Both top and bottom surfaces are hydrophilic, (ii) Case B: both top and bottom surfaces are hydrophobic. For all cases, equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. Then the lower wall was set to four different temperatures such as 110 K, 120 K, 130 K and 140 K to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat fluxes normal to top and bottom walls were estimated and discussed to illuminate the effectiveness of heat transfer in both hydrophilic and hydrophobic confinement at various boundary temperatures of the bottom plate.

  1. Modeling of thin film explosive boiling—surface evaporation and electron thermal conductivity effect

    Science.gov (United States)

    Mazhukin, V. I.; Samokhin, A. A.; Shapranov, A. V.; Demin, M. M.

    2015-01-01

    Phase transition in a thin liquid Al film during its rapid (sub) nanosecond homogeneous heating is studied in the framework of molecular dynamics simulation with electron thermal conductivity. The results are compared with our previous results without consideration of electron thermal conductivity. Surface evaporation leads to surface cooling and this effect is more pronounced at lower heating rates in the case without electron thermal conductivity. For the case with electron thermal conductivity, the obtained results suggest the existence of four different regimes of film behavior depending on the heating rate: quasi-stationary surface evaporation regime with relatively small fluctuations at the low heating rates, explosive (volume) boiling which is initiated as growth of a single fluctuation, spinodal decomposition with many fluctuations growing simultaneously and supercritical fluid expansion with no pronounced fluctuations at the high heating rates. Our calculations also show that the duration and magnitude of the explosive boiling pressure pulse, which occurs at the threshold heating rate, are about 0.3 ns and one third of the critical pressure value, respectively. Information of this kind is needed to determine the optimal conditions for the measurement of the critical parameters of different materials in laser ablation experiments.

  2. Realization of PbS thin films by reactive evaporation technique for possible opto-electronic applications

    Science.gov (United States)

    A, Abhilash; Nair, Aparna S.; S, Rajasree; E, Hiba Rahman; Pradeep, B.

    2015-06-01

    Stoichiometric Lead sulphide (PbS) thin films were successfully prepared on glass substrates by reactive evaporation technique. Elemental evaporation of lead and sulphur taken in different sources onto substrates held at temperature of 400±5K employed in the present study. The structural as well as compositional studies compromises compound formation. Electrical transport properties and optical co-efficient were evaluated from appropriate characterization techniques.

  3. Nonlinear dynamics of non-isothermal thin films and droplets with evaporation and condensation on a rigid wall

    OpenAIRE

    Colinet, Pierre; Rossomme, Séverine; Rednikov, Alexei

    2008-01-01

    Evaporation/condensation processes of thin films of pure liquids lying on heated or cooled horizontal homogeneous and flat substrates are studied thanks to a lubrication-type equation describing the evolution of their deformable free surface. The one-sided model is restricted to a pure vapour phase at constant pressure, and includes the interfacial kinetic resistance to evaporation, the capillary and disjoining pressures, together with the thermodynamic influence of these last two effects on ...

  4. Low temperature, fast deposition of metallic titanium nitride films using plasma activated reactive evaporation

    International Nuclear Information System (INIS)

    Titanium and titanium nitride thin films were deposited on silica glass and W substrates at a high coating growth rate by plasma-activated reactive evaporation (ARE). The crystal structure, preferred orientation and grain size of the coatings were determined by x-ray diffraction (XRD) technique using Cu-Kα x rays. The analysis of the coating morphology was performed by field-emission scanning electron microscopy (FE-SEM). The composition of the films was analyzed by Auger electron spectroscopy (AES) and electron-probe microanalysis (EPMA). The titanium and titanium nitride condensates were collected on a carbon-coated collodion film then characterized by transmission electron microscopy (TEM) in order to study the structures of the deposits at very short deposition times. The resistivity of the films was measured by using the four-point-probe method. The titanium coatings were found to consist of very fine particles (40 nm in grain size) and to exhibit a strong (002) texture. The titanium nitride coatings were substoichiometric (TiNx,xx coatings obtained at low temperature and a high growth rate in this work exhibited a rather high electrical conductivity

  5. Influence of boat material on the structure, stoichiometry and optical properties of gallium sulphide films prepared by thermal evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Pritty [National Centre for Compositional Characterization of Materials, Bhabha Atomic Research Centre, ECIL Post, Hyderabad 500062 (India); Kumar, Sanjiv, E-mail: sanjucccm@rediffmail.com [National Centre for Compositional Characterization of Materials, Bhabha Atomic Research Centre, ECIL Post, Hyderabad 500062 (India); Sahoo, N.K. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2015-01-15

    The paper describes the deposition of thin films of gallium sulphide on soda-lime glass substrates by thermal evaporation of chemically synthesized powders consisting of gallium sulphide and gallium oxyhydroxide from a Mo or Ta boat and the evolution of their compositional, structural and optical properties on vacuum annealing. The films deposited from Mo or Ta boats possessed distinctly different properties. The Mo-boat evaporated pristine films were amorphous, transparent (α ∼ 10{sup 3} cm{sup −1}) in visible region and had a direct band gap of about 3.2 eV. Vacuum annealing at 723 K brought about their crystallization predominantly into cubic γ-Ga{sub 2}S{sub 3} and a blue shift by about 0.2 eV. The Ta-boat evaporated pristine films were also amorphous but were absorbing (α ∼ 10{sup 4} cm{sup −1}) and had a direct band gap of about 2.1 eV. These crystallized into hexagonal GaS and experienced a blue shift by more than 1.0 eV on vacuum annealing at 723 K. The dissimilar properties of the two kinds of films arose mainly from their different atomic compositions. The Mo-boat evaporated pristine films contained Ga and S in ∼1:1 atomic proportions while those prepared using Ta-boat were Ga rich which impaired their transmission characteristics. The former composition favoured the stabilization of S rich gallium sulphide (Ga{sub 2}S{sub 3}) phase while the latter stabilised S deficient species, GaS. Besides inducing crystallization, vacuum annealing at 723 K also caused the diffusion of Ga in excess of atomic composition of the phase formed, into soda-lime glass which improved the optical transmission of the films. Gallium oxyhydroxide, an inevitable co-product of the chemical synthetic process, in the evaporant introduced oxygen and hydrogen impurities in the films which do not seem to significantly influence their optical properties. - Highlights: • Gallium sulphide films are prepared by thermal evaporation from a Mo or Ta boat. • Mo

  6. Improved Modeling Approaches for Constrained Sintering of Bi-Layered Porous Structures

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Frandsen, Henrik Lund; Esposito, Vincenzo;

    2012-01-01

    Shape instabilities during constrained sintering experiment of bi-layer porous and dense cerium gadolinium oxide (CGO) structures have been analyzed. An analytical and a numerical model based on the continuum theory of sintering has been implemented to describe the evolution of bow and densificat...

  7. Thickness effect on properties of titanium film deposited by d.c. magnetron sputtering and electron beam evaporation techniques

    Indian Academy of Sciences (India)

    Nishat Arshi; Junqing Lu; Chan Gyu Lee; Jae Hong Yoon; Bon Heun Koo; Faheem Ahmed

    2013-10-01

    This paper reports effect of thickness on the properties of titanium (Ti) film deposited on Si/SiO2 (100) substrate using two different methods: d.c. magnetron sputtering and electron beam (e-beam) evaporation technique. The structural and morphological characterization of Ti film were performed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). XRD pattern revealed that the films deposited using d.c. magnetron sputtering have HCP symmetry with preferred orientation along (002) plane, while those deposited with e-beam evaporation possessed fcc symmetry with preferred orientation along (200) plane. The presence of metallic Ti was also confirmed by XPS analysis. FESEM images depicted that the finite sized grains were uniformly distributed on the surface and AFM micrographs revealed roughness of the film. The electrical resistivity measured using four-point probe showed that the film deposited using d.c. magnetron sputtering has lower resistivity of ∼13 cm than the film deposited using e-beam evaporation technique, i.e. ∼60 cm. The hardness of Ti films deposited using d.c. magnetron sputtering has lower value (∼7.9 GPa) than the film deposited using e-beam technique (∼9.4 GPa).

  8. Modeling evaporation, ion-beam assist, and magnetron sputtering of thin metal films over realistic time scales

    Science.gov (United States)

    Blackwell, S.; Smith, R.; Kenny, S. D.; Walls, J. M.

    2012-07-01

    A long-time-scale dynamics technique has been used to model the evaporation, ion-beam assist, and magnetron sputtering of thin metal films over realistic time scales. Two fcc metals have been investigated: silver and aluminum. We illustrate how the technique can be used to model growth of these films over experimental time scales, while investigating individual growth mechanisms and surface diffusion events. Long-time dynamics is achieved through an on-the-fly kinetic Monte Carlo method, which determines diffusion pathways and barriers, in parallel, with no prior knowledge of the involved transitions. It was found that Ag has the ability to grow smooth surfaces, using several mechanisms including multiple-atom concerted motion, exchange mechanisms, and damage and repair systems. Ag {111} and {100} grew dense, complete, and crystalline film when sputtering was simulated, whereas evaporation produced incomplete layers. The inclusion of Ar in the ion-beam-assisted evaporation of Ag {111} aided growth by transferring more energy to the surface atoms allowing increased diffusion. Al {111}, however, shows slightly different patterns; growth via evaporation and magnetron sputtering shows only slight differences and the inclusion of the ion-beam assist actually damages the film beyond repair, producing subsurface Ar clusters where Al atoms were displaced creating voids throughout the film. Al {100}, similar to Ag {100}, grows denser and more complete film when grown via sputtering rather than evaporation. Results show that the energy of the deposition method used plays a vital role in the resulting thin film and substrate quality.

  9. Combinatorial matrix-assisted pulsed laser evaporation: Single-step synthesis of biopolymer compositional gradient thin film assemblies

    Science.gov (United States)

    Sima, F.; Axente, E.; Sima, L. E.; Tuyel, U.; Eroglu, M. S.; Serban, N.; Ristoscu, C.; Petrescu, S. M.; Toksoy Oner, E.; Mihailescu, I. N.

    2012-12-01

    We introduce a combinatorial approach for the fabrication of organic biopolymer thin films. Structures with compositional gradient are obtained by simultaneous laser vaporization of two distinct targets. Matrix-assisted pulsed laser evaporation deposition method was applied to obtain a compositional library of levan and oxidized levan in form of thin film. The gradient of film composition and structure was demonstrated by infrared spectroscopy while in vitro cell culture assays illustrated characteristic responses of cells to specific surface regions. The method can rapidly generate discrete areas of organic film compositions with improved properties than starting materials.

  10. Effect of annealing temperature on the optical properties of thermally evaporated tin phthalocyanine thin films

    International Nuclear Information System (INIS)

    Thin films of tin phthalocyanine were prepared on quartz substrates by thermal evaporation technique. The optical properties were investigated using a spectrophotometric measurement of transmittance and reflectance at normal incidence of light in the wavelength range 200-2500 nm for the as-deposited and the annealed films. Absorption spectra of the films show intense B, N and C bands in the UV region followed by Q-band in the visible region. The values of the oscillator strength and the electric dipole strength were estimated. The optical constants were accurately determined using Murmann's equations, which allow obtaining the real and the imaginary parts of the complex refractive index. The absorption analysis has been also performed to determine the type of electronic transition and the optical energy band gap. The dispersion of the refractive index, n, is discussed in terms of the single oscillator model. The dispersion parameters and the ratio of free carrier concentration to the free carrier effective mass were also estimated.

  11. High conductivity a-C:N thin films prepared by electron gun evaporation

    International Nuclear Information System (INIS)

    By employing electron beam evaporation, amorphous carbon nitride (a-C:N) thin films, with a low nitrogen content (∼ 1%), were prepared on Si(110) and glass substrates at about 150 deg. C. The source was a graphite target and an ambient of N2 was introduced into the growing chamber. The source-substrate distance (SSD) was the main parameter that was intentionally varied. Electron dispersion spectroscopy measurements indicate the nitrogen concentration in the layer as ∼ 1%. The dark electrical conductivity (σ) of layers was very sensitive to SSD variation, changing up to six orders of magnitude when this parameter was varied from 10.5 to 23.5 cm. A maximum value of σ = 1 x 103 Ω-1 cm-1 at room temperature was obtained when the SSD was equal to 15.5 cm. We have deduced that, in accordance with the Ferrari-Robertson model (FRM), our samples are localized in the second stage of the amorphization trajectory of FRM. When the SSD increases the C atoms have more probability to collide with N2 molecules, and the content of nitrogen in the a-C film increases. The amorphization trajectory followed by the films with an SSD increase is from nanocrystalline graphite to amorphous carbon. The changes in the amorphization are due to the nitrogen content in the layers

  12. Study of optical and structural properties of CZTS thin films grown by co-evaporation and spray pyrolysis

    Science.gov (United States)

    Moreno, R.; Ramirez, E. A.; Gordillo Guzmán, G.

    2016-02-01

    Results regarding optical and structural properties of Cu2ZnSnS4 (CZTS) thin films prepared by co-evaporation using a novel procedure are compared with those obtained with CZTS films grown using a solution based route. The lattice strain ε and crystallite size D of CZTS films prepared by co-evaporation and by spray pyrolysis were estimated through X-ray diffraction (XRD) measurements using Williamson-Hall-isotropic strain model. The results of estimated average crystallite size of CZTS films by Scherrer and Williamson-Hall plot methods were compared with AFM (atomic force microscopy) measurements. It was found that the average crystallite size measured by Williamson-Hall plot methods agree quite well with AFM results. Further, information regarding the influence of preparation method on both, crystalline phases and the formation of structural defects was achieved through Raman and Urbach energy measurements.

  13. Deposition of matrix-free fullerene films with improved morphology by matrix-assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster, Søren;

    2013-01-01

    Thin films of C60 were deposited by matrix-assisted pulsed laser evaporation (MAPLE) from a frozen target of anisole with 0.67 wt% C60. Above a fluence of 1.5 J/cm2 the C60 films are strongly non-uniform and are resulting from transfer of matrix-droplets containing fullerenes. At low fluence the...... fullerene molecules in the films are intact, the surface morphology is substantially improved and there are no measurable traces of the matrix molecules in the film. This may indicate a regime of dominant evaporation at low fluence which merges into the MAPLE regime of liquid ejection of the host matrix at...

  14. APPLICATION OF A THIN FILM EVAPORATOR SYSTEM FOR MANAGEMENT OF LIQUID HIGH-LEVEL WASTES AT HANFORD

    Energy Technology Data Exchange (ETDEWEB)

    TEDESCHI AR; WILSON RA

    2010-01-14

    A modular, transportable evaporator system, using thin film evaporative technology, is planned for deployment at the Hanford radioactive waste storage tank complex. This technology, herein referred to as a wiped film evaporator (WFE), will be located at grade level above an underground storage tank to receive pumped liquids, concentrate the liquid stream from 1.1 specific gravity to approximately 1.4 and then return the concentrated solution back into the tank. Water is removed by evaporation at an internal heated drum surface exposed to high vacuum. The condensed water stream will be shipped to the site effluent treatment facility for final disposal. This operation provides significant risk mitigation to failure of the aging 242-A Evaporator facility; the only operating evaporative system at Hanford maximizing waste storage. This technology is being implemented through a development and deployment project by the tank farm operating contractor, Washington River Protection Solutions (WRPS), for the Office of River Protection/Department of Energy (ORP/DOE), through Columbia Energy & Environmental Services, Inc. (Columbia Energy). The project will finalize technology maturity and install a system at one of the double-shell tank farms. This paper discusses results of pre-project pilot-scale testing by Columbia Energy and ongoing technology maturation development scope through fiscal year 2012, including planned additional pilot-scale and full-scale simulant testing and operation with actual radioactive tank waste.

  15. Application Of A Thin Film Evaporator System For Management Of Liquid High-Level Wastes At Hanford

    International Nuclear Information System (INIS)

    A modular, transportable evaporator system, using thin film evaporative technology, is planned for deployment at the Hanford radioactive waste storage tank complex. This technology, herein referred to as a wiped film evaporator (WFE), will be located at grade level above an underground storage tank to receive pumped liquids, concentrate the liquid stream from 1.1 specific gravity to approximately 1.4 and then return the concentrated solution back into the tank. Water is removed by evaporation at an internal heated drum surface exposed to high vacuum. The condensed water stream will be shipped to the site effluent treatment facility for final disposal. This operation provides significant risk mitigation to failure of the aging 242-A Evaporator facility; the only operating evaporative system at Hanford maximizing waste storage. This technology is being implemented through a development and deployment project by the tank farm operating contractor, Washington River Protection Solutions (WRPS), for the Office of River Protection/Department of Energy (ORP/DOE), through Columbia Energy and Environmental Services, Inc. (Columbia Energy). The project will finalize technology maturity and install a system at one of the double-shell tank farms. This paper discusses results of pre-project pilot-scale testing by Columbia Energy and ongoing technology maturation development scope through fiscal year 2012, including planned additional pilot-scale and full-scale simulant testing and operation with actual radioactive tank waste.

  16. Comparison of two turbulent models in simulating evaporating liquid film in a wiped molecular distillator

    Institute of Scientific and Technical Information of China (English)

    XIANG Aishuang; XU Songlin

    2005-01-01

    Velocity field of evaporating liquid film in a wiped molecular distillator was simulated with a computational fluid dynamics (CFD) software, and two turbulent models treating near-wall flow were compared. Differences between wiped and other molecular distillations were introduced to explain why turbulent model should be used in this simulation. Three assumptions were made in order to simplify simulating processes. In rotating coordinate system, fixed other settings, the above two turbulent models were used, and the volume of fluid (VOF) multiphase model was also applied to tracking the liquid-gas surface. Both of the simulating results are basically identical with real situation and were compared in several aspects. It was concluded that both of the turbulent models are suitable in this simulation.

  17. Fabrication and Characterization of High-Crystalline Nanoporous ZnO Thin Films by Modified Thermal Evaporation System

    Science.gov (United States)

    Islam, M. S.; Hossain, M. F.; Razzak, S. M. A.; Haque, M. M.; Saha, D. K.

    2016-05-01

    The aim of this work is to fabricate high-crystalline nanoporous zinc oxide (ZnO) thin films by a modified thermal evaporation system. First, zinc thin films have been deposited on bare glass substrate by the modified thermal evaporation system with pressure of 0.05mbar, source-substrate distance of 3cm and source temperature 700∘C. Then, high-crystalline ZnO thin film is obtained by annealing at 500∘C for 2h in atmosphere. The prepared ZnO films are characterized with various deposition times of 10min and 20min. The structural property was investigated by X-ray diffractometer (XRD). The optical bandgap and absorbance/transmittance of these films are examined by ultraviolet/visible spectrophotometer. The surface morphological property has been observed by scanning electron microscope (SEM). ZnO films have showed uniform nanoporous surface with high-crystalline hexagonal wurtzite structure. The ZnO films prepared with 20min has excitation absorption-edge at 369nm, which is blueshifted with respect to the bulk absorption-edge appearing at 380nm. The gap energy of ZnO film is decreased from 3.14eV to 3.09eV with increase of the deposition time, which can enhance the excitation of ZnO films by the near visible light, and is suitable for the application of photocatalyst of waste water cleaning and polluted air purification.

  18. Thermoluminescence of Y2O3:Tb3+ thin films deposited by electron beam evaporation

    International Nuclear Information System (INIS)

    Most thermoluminescent materials are created using crystal growth techniques; however, it would be of great utility to identify those few thermoluminescent materials that can be deposited using simpler methods, for example to be compatible with the early portions of a silicon integrated circuit or microelectromechanical fabrication process. In this work, thin films of yttrium oxide with a terbium impurity (Y2O3:Tb) were deposited on silicon wafers by electron beam evaporation. The source for the Y2O3:Tb was made by combining Y2O3 and Tb4O7 powders. The approximate thicknesses of the deposited films were 350 nm. After deposition, the films were annealed at 1100 °C for 30 s to improve crystallinity. There is a strong correlation between the x-ray diffraction (XRD) peak intensity and the thermoluminescent glow curve intensity. The glow curve displays at least two peaks at 140 °C and 230 °C. The emission spectra was measured using successive runs with a monochromator set to a different wavelength for each run. There are two main emission peaks at 490 nm and 540 nm. The terbium impurity concentration of approximately 1 mol% was measured using Rutherford backscattering spectrometry (RBS). The Y2O3:Tb is sensitive to UV, x-ray, and gamma radiation. The luminescent intensity per unit mass of UV irradiated Y2O3:Tb was about 2 times that of x-ray irradiated TLD-100. -- Highlights: • Y2O3:Tb3+ thin film can be deposited using the common microfabrication technique of electron beam evaporation. • The Y2O3:Tb3+ requires an anneal of at least 900 °C to show thermoluminescence and 1100 °C anneal for the strongest thermoluminescent signal. • The Y2O3:Tb3+ will show a glow curve after being exposed to ionizing radiation from UV, x-ray, and gamma ray sources. • The luminescent intensity per unit mass of the UV irradiated Y2O3:Tb3+ is twice that of x-ray irradiated TLD-100(LiF:Ti, Mg)

  19. Study of magnetic anisotropy and magnetoresistance effects in ferromagnetic Co/Au multilayer films prepared by oblique incidence evaporation method

    International Nuclear Information System (INIS)

    A series of e-beam evaporated [Co10 A/Aut A]20 multilayers has been deposited on 1.69 mm2 glass substrates. The samples were examined with vibrating sample magnetometer, low angle X-ray diffraction, and magnetoresistance (MR) measurements. The effects of oblique incidence evaporation and magnetic annealing on the anisotropy, microstructure, and different components of MR are examined. After magnetic annealing, the multilayer [Co10 A/Au20 A]20 produced at the incidence angle of 45o showed a strong anisotropy and the easy axis of the anisotropy is along the perpendicular (x-axis; along the film plane) to the incidence of evaporation. MR at room temperature has two components: isotropic and anisotropic. The magnetoresistance effects are found to be larger in the uniaxial films, with both anisotropic and giant magnetoresistance peaking at around 20 A Au layer thickness

  20. Chemical reaction of atomic oxygen with evaporated films of copper, part 4

    Science.gov (United States)

    Fromhold, A. T.; Williams, J. R.

    1990-01-01

    Evaporated copper films were exposed to an atomic oxygen flux of 1.4 x 10(exp 17) atoms/sq cm per sec at temperatures in the range 285 to 375 F (140 to 191 C) for time intervals between 2 and 50 minutes. Rutherford backscattering spectroscopy (RBS) was used to determine the thickness of the oxide layers formed and the ratio of the number of copper to oxygen atoms in the layers. Oxide film thicknesses ranged from 50 to 3000 A (0.005 to 0.3 microns, or equivalently, 5 x 10(exp -9) to 3 x 10(exp -7); it was determined that the primary oxide phase was Cu2O. The growth law was found to be parabolic (L(t) varies as t(exp 1/2)), in which the oxide thickness L(t) increases as the square root of the exposure time t. The analysis of the data is consistent with either of the two parabolic growth laws. (The thin-film parabolic growth law is based on the assumption that the process is diffusion controlled, with the space charge within the growing oxide layer being negligible. The thick-film parabolic growth law is also based on a diffusion controlled process, but space-charge neutrality prevails locally within very thick oxides.) In the absence of a voltage measurement across the growing oxide, a distinction between the two mechanisms cannot be made, nor can growth by the diffusion of neutral atomic oxygen be entirely ruled out. The activation energy for the reaction is on the order of 1.1 eV (1.76 x 10(exp -19) joule, or equivalently, 25.3 kcal/mole).

  1. Synthesis of thermally evaporated ZnSe thin film at room temperature

    International Nuclear Information System (INIS)

    Zinc selenide (ZnSe) thin film on glass substrates were prepared by thermal evaporation under high vacuum using the quasi-closed volume technique at room temperature (300 ± 2 K). The deposited ZnSe properties were assessed via X-ray diffraction, atomic force microscope (AFM), UV-Vis specrophotometry, Raman spectroscopy, photo-luminescence, Fourier transform infrared spectroscopy (FT-IR) and spectroscopic ellipsometry. The X-ray diffraction patterns of the film exhibited reflection corresponding to the cubic (111) phase (2θ = 27.20 deg.). This analysis indicated that the sample is polycrystalline and have cubic (Zinc blende) structure. The crystallites were preferentially oriented with the (111) planes parallel to the substrates. The AFM images showed that the ZnSe films have smooth morphology with roughness 6.74 nm. The transmittance spectrum revealed a high transmission of 89% in the infrared region (≥ 600 nm) and a low transmission of 40% at 450 nm. The maximum transmission of 89.6% was observed at 640 nm. Optical band-gap was calculated from the transmission data of specrophotometry, photo-luminescence and ellipsometry and was 2.76, 2.74 and 2.82 eV respectively. Raman spectroscopic studies revealed two longitudinal optical phonon modes at 252 cm-1 and 500 cm-1. In photoluminescence study, the luminescence peaks was observed at 452 nm corresponding to band to band emission. FT-IR study illustrated the existence of Zn-Se bonding in ZnSe thin film. The optical constants were calculated using spectroscopic ellipsometry and were determined from the best fit ellipsometric data in the wavelength regime of interest from 370-1000 nm. These results manifested excellent room temperature ZnSe synthesis and characteristics for opto-electronics technologies.

  2. A Simulation Study on Effect of SurfaceFilm-Forming{1mmMaterial on Water Evaporation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A greenhouse experiment was conducted to investigate the effect ofsurface film-forming material (SFFM), a mixture of1618-octadecanols by emulsification, on water evaporation.Air-dried soil with distilled water was incubated firstly for 7 days toreestablish soil biological activity and then for another 7 days aftertreated with SFFM at rates of 0, 1, 2, 4, 6 and 8 g m{-2,respectively. Everyday during the 7-day incubation after addition ofSFFM, water losses due to evaporation were measured by an electronicbalance. The rate of water evaporation with the addition of SFFM wasreduced significantly compared with the control treatment and theeffectiveness of SFFM on water evaporation reduced with time. Accordingto the equation expressions of the effect of SFFM on water evaporation,the half-life of effectiveness of SFFM on water evaporation wasintroduced and calculated to analyze quantitative relationship betweenthe effectiveness of SFFM on water evaporation and the addition rate ofSFFM. The calculated half-life increased with the addition rate of SFFMand the confidence of the calculated values of the half-life was high,suggesting that the half-life of effectiveness of SFFM on waterevaporation could be described quantitatively and may be helpful forameliorating application method of SFFM and screening surface-filmforming materials in order to improve nitrogen fertilizer useefficiency in flooded rice fields.

  3. Substrate bias effect on crystallinity of polycrystalline silicon thin films prepared by pulsed ion-beam evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Fazlat; Gunji, Michiharu; Yang, Sung-Chae; Suzuki, Tsuneo; Suematsu, Hisayuki; Jiang, Weihua; Yatsui, Kiyoshi [Nagaoka Univ. of Technology, Extreme Energy-Density Research Inst., Nagaoka, Niigata (Japan)

    2002-06-01

    The deposition of polycrystalline silicon thin films has been tried by a pulsed ion-beam evaporation method, where high crystallinity and deposition rate have been achieved without heating the substrate. The crystallinity and the deposition rate were improved by applying bias voltage to the substrate, where instantaneous substrate heating might have occurred by ion-bombardment. (author)

  4. Substrate bias effect on crystallinity of polycrystalline silicon thin films prepared by pulsed ion-beam evaporation method

    International Nuclear Information System (INIS)

    The deposition of polycrystalline silicon thin films has been tried by a pulsed ion-beam evaporation method, where high crystallinity and deposition rate have been achieved without heating the substrate. The crystallinity and the deposition rate were improved by applying bias voltage to the substrate, where instantaneous substrate heating might have occurred by ion-bombardment. (author)

  5. Structural characterization of thin films based on II-VI ternary compounds deposited by evaporation

    International Nuclear Information System (INIS)

    Thin films of Zn(S, Se) (Zn, In)Se and Cd(S, Te) compounds, deposited by evaporation were characterized through X-ray diffraction (XRD) measurements and analyzed with the help of a simulation program. The interest in studying these materials is due to their potential for photovoltaic applications, especially as buffer materials in Cu(In,Ga)Se2 (CIGS) and CdTe based solar cells. The XRD measurements allowed us to determine the effect of the chemical composition on the structure and lattice parameter, which must be known to predict an optimum mechanical match between the buffer and absorber layers; a good mechanical match improves the hetero-interface of the solar cell. The studies revealed that In-rich Zn xIn1-xSe films and Te-rich CdS xTe1-x films grow with hexagonal structure; however, their structure is changed to cubic when they become Zn-rich and Te-rich, respectively. On the contrary, the Zn xIn1-xSe films grow with cubic structure, independently of its chemical composition. It was also found that the variation of the chemical composition leads to a significant variation of the optical gap Eg, which was determined by extrapolation of the curve (αhν)2 vs. hν, assuming that, for this type of compounds, the relation αhν A(hν - Eg)1/2 is valid. It was observed, in the three type of compounds studied, that their Eg values increase with the decreasing of the lattice constant, which in turn varies according to Vegard's Law. Comparing the lattice parameters of the ZnS xSe1-x and Zn xIn1-xSe compounds, with those reported in the literature for Cu(In1-x,Ga x)Se2 thin films, helpful information was found to achieve a good lattice match between the studied II-VI compounds and the CIGS film

  6. CONTEMPORARY APPROACHES FOR BI-LAYER TECHNOLOGY OF DRUGS THROUGH ORAL ROUTE: AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    Rishikesh*, M. A. Bhuiyan, S. M. Ashraful Islam, I. Dewan, Md. A. Islam and Md. S.- Ul H. Miah

    2013-04-01

    Full Text Available ABSTRACT: Bi-layer tablet technology for bimodal release of drug and co-administration of drugs via oral route has been engaged a significant place in the field of drug delivery technology. At present, several pharmaceutical companies are developing bilayer tablet for co-administration of drugs to improve the therapeutic efficacy as well as to reduce the chances of drug-drug interaction. This review indicates the different aspects of drug release mechanism, different strategies of drug release, various techniques for bilayer tablet, and the influence of different process and formulation parameters must be considered during the development of bilayer tablet. Bi-layer tablet is suitable for sequential release of two drugs in combination, separate two incompatible substances, and also for sustained release tablet in which one layer is immediate release as initial dose and second layer is maintenance dose.

  7. Structural, optical and photoluminescence properties of electron beam evaporated CdSe sub 1-x Te sub x films

    Energy Technology Data Exchange (ETDEWEB)

    Mangalhara, J.P.; Thangaraj, R.; Agnihotri, O.P. (Indian Inst. of Tech., New Delhi (India). Semiconductor Engineering Lab.)

    1989-11-01

    CdSe{sub 1-x}Te{sub x} (0lexle1) films have been prepared by electron beam evaporation using pellets made by mixing CdSe and CdTe powder in appropriate ratios. For the films prepared at 200deg C substrate temperature, the XRD pattern of CdTe (x=1) showed the presence of free Te while films of all other compositions were single phase in nature. The effect of composition and substrate temperature on transmission spectra was studied. The photoluminescence studies showed sub-band-gap luminescence throughout the composition range. Annealed CdSe{sub 0.8}Te{sub 0.2} films showed better photoluminescence efficiency as compared to as-grown films. The refractive index was found to increase with substrate temperature for CdSe{sub 0.8}Te{sub 0.2} films. (orig.).

  8. Nanoparticle Thin Films for Gas Sensors Prepared by Matrix Assisted Pulsed Laser Evaporation

    Directory of Open Access Journals (Sweden)

    Roberto Rella

    2009-04-01

    Full Text Available The matrix assisted pulsed laser evaporation (MAPLE technique has been used for the deposition of metal dioxide (TiO2, SnO2 nanoparticle thin films for gas sensor applications. For this purpose, colloidal metal dioxide nanoparticles were diluted in volatile solvents, the solution was frozen at the liquid nitrogen temperature and irradiated with a pulsed excimer laser. The dioxide nanoparticles were deposited on Si and Al2O3 substrates. A rather uniform distribution of TiO2 nanoparticles with an average size of about 10 nm and of SnO2 nanoparticles with an average size of about 3 nm was obtained, as demonstrated by high resolution scanning electron microscopy (SEM-FEG inspections. Gas-sensing devices based on the resistive transduction mechanism were fabricated by depositing the nanoparticle thin films onto suitable rough alumina substrates equipped with interdigitated electrical contacts and heating elements. Electrical characterization measurements were carried out in controlled environment. The results of the gas-sensing tests towards low concentrations of ethanol and acetone vapors are reported. Typical gas sensor parameters (gas responses, response/recovery time, sensitivity, and low detection limit towards ethanol and acetone are presented.

  9. An experimental investigation of angular resolved energy distributions of atoms sputtered from evaporated aluminum films

    International Nuclear Information System (INIS)

    A study of angular resolved velocity (energy) distributions of atoms sputtered from in situ prepared metal films is described in this contribution. The velocity resolution of the set-up is based on the pulsed laser-induced fluorescence technique, i.e., scanning the narrow bandwidth dye laser radiation over the Doppler broadened absorption profile of the sputtered particles. The arrangement of the vacuum vessel and fluorescence detection optics provides the means for an independent selection of the observed emission direction and the angle of incidence. A pulsed ion gun is applied to bombard the target with noble gas ions in the energy range between 200 and 500 eV. The target assembly allows the preparation of thin metal films by evaporation on optically polished glass substrates without break of the vacuum. We report on measurements obtained with this arrangement, i.e., the determination of energy distributions of sputtered aluminum atoms. The bombardment at both the normal and the oblique incidence of the ion beam are contained in the investigation. Pronounced anisotropic effects are observed in both cases. In the case of oblique bombardment the shape of the distributions reflects cascade effects as well as single collision properties. The energy distribution is approximated with the aid of an energy spectrum involving a superposition of exponential functions. The experimental results are compared with simulations obtained by the Monte Carlo code TRIM.SP

  10. Effect of He{sup +} irradiation on the optical properties of vacuum evaporated silver indium selenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh Kumar, M.C., E-mail: santhoshmc@yahoo.co [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli, Tamil Nadu 620 015 (India); Pradeep, B. [Solid State Physics Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682 022 (India)

    2010-04-09

    We prepared polycrystalline silver indium selenide thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The samples were subjected to the irradiation of 1.26 M eV He{sup +} ion. The effect of irradiation on the optical properties has been investigated for different fluencies of He{sup +}. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. It is observed that the band gap of silver indium selenide thin films decreases gradually from 1.17 to 0.82 eV with ion fluency.

  11. On the evaporation rate of ultra-thin liquid film at the nanostructured surface: A molecular dynamics study

    OpenAIRE

    Nagayama, Gyoko; Kawagoe, Masako; Tokunaga, Atsushi; Tsuruta, Takaharu

    2010-01-01

    Molecular dynamic (MD) simulations have been carried out to study the effect of the nanostructures on the evaporation rate of the ultra-thin liquid film at the solid surface. Simple Lennard-Jones (LJ) fluids are simulated as the ultra-thin liquid film in the non-equilibrium simulation system. The liquid film is confined in a nanochannel composed of two solid surfaces designed with nanostructures in a shape of molecular-scale unevenness. The potential function between solid and liquid molecule...

  12. Matrix assisted pulsed laser evaporation of pullulan tailor-made biomaterial thin films for controlled drug delivery systems

    International Nuclear Information System (INIS)

    We report the first successful deposition of cinnamate-pullulan polysaccharide thin films by Matrix Assisted Pulsed Laser Evaporation (MAPLE). Thin film depositions were performed in vacuum using a KrF* excimer laser source (λ = 248 nm, τ ∼ 20 ns) operated at a repetition rate of 10 Hz. The dependence on incident laser fluence of the induced surface morphology is studied. We demonstrated by Raman spectroscopy that our MAPLE-deposited cinnamate-pullulan thin films are composed of starting materials preserving their chemical structures, with no impurities

  13. Unraveling the impacts of IXP in internet ecosystem using bi-layered network

    Science.gov (United States)

    Fan, Zhongyan; Tang, Wallace K. S.

    2016-08-01

    The Internet is a huge complex network, consisting of tens thousands of Autonomous Systems (ASes). Being a logical fabric of the Internet, the AS-level topology serves as a manageable and useful vehicle for the study of Internet characteristics. However, Internet exchange points (IXPs) have been ignored in previous studies despite of being one of the primary mechanisms for AS interconnections and playing an important role for improving data traffic. In this paper, a novel bi-layered network model is proposed to present an IXP-AS topology. The bi-layered network is built based on the actual architecture, from which a comprehensive study of current AS ecosystem and the impacts of IXP can be made. As revealed by network metrics applied onto the bi-layered network, IXP is always of higher centrality as compared with ASes, well matching its role. By comparing the results in 2009 and 2014, rapid growth in IXP number, membership and impacts are noticed. There are over 98% source-destination pairs routes (with shortest path routing protocol) affected by IXP in 2014. Our results also show that, being an IXP member is more favorable than being a non-member, hence it attracts many ASes, especially those with low centrality, in recent years.

  14. Nanocrystalline biphasic resorbable calcium phosphate (HAp/β-TCP) thin film prepared by electron beam evaporation technique

    Energy Technology Data Exchange (ETDEWEB)

    Elayaraja, K.; Chandra, V. Sarath; Joshy, M.I. Ahymah; Suganthi, R.V. [Crystal Growth Centre, Anna University, Chennai 600025, Tamil Nadu (India); Asokan, K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Kalkura, S. Narayana, E-mail: kalkura@yahoo.com [Crystal Growth Centre, Anna University, Chennai 600025, Tamil Nadu (India)

    2013-06-01

    Biphasic calcium phosphate (BCP) thin film having resorbable β-tricalcium phosphate (β-TCP) and non-resorbable hydroxyapatite (HAp) phases having enhanced bioactivity was synthesized by electron beam evaporation technique. Nanosized BCP was deposited as a layer (500 nm) on (0 0 1) silicon substrate by electron beam evaporation and crystalline phase of samples were found to improve on annealing at 700 °C. Uniform deposition of calcium phosphate on silicon substrate was verified from elemental mapping using scanning electron microscope (SEM-EDX). Annealing of the samples led to a decrease in surface roughness, hydrophobicity and dissolution of the coating layer. Amoxicillin loaded thin films exhibited significant bacterial resistance. In addition, BCP thin films did not exhibit any cytotoxicity. Antibiotics incorporated BCP coated implants might prevent the post-surgical infections and could promote bone-bonding of orthopedic devices.

  15. Nanocrystalline biphasic resorbable calcium phosphate (HAp/β-TCP) thin film prepared by electron beam evaporation technique

    International Nuclear Information System (INIS)

    Biphasic calcium phosphate (BCP) thin film having resorbable β-tricalcium phosphate (β-TCP) and non-resorbable hydroxyapatite (HAp) phases having enhanced bioactivity was synthesized by electron beam evaporation technique. Nanosized BCP was deposited as a layer (500 nm) on (0 0 1) silicon substrate by electron beam evaporation and crystalline phase of samples were found to improve on annealing at 700 °C. Uniform deposition of calcium phosphate on silicon substrate was verified from elemental mapping using scanning electron microscope (SEM-EDX). Annealing of the samples led to a decrease in surface roughness, hydrophobicity and dissolution of the coating layer. Amoxicillin loaded thin films exhibited significant bacterial resistance. In addition, BCP thin films did not exhibit any cytotoxicity. Antibiotics incorporated BCP coated implants might prevent the post-surgical infections and could promote bone-bonding of orthopedic devices.

  16. Preparation and Characterization of Antimony Doped Tin Oxide Thin Films Synthesized by Co-Evaporation of Sn and Sb using Plasma Assisted Thermal Evaporation

    Directory of Open Access Journals (Sweden)

    C. Jariwala

    2013-05-01

    Full Text Available Tin oxide (SnO2 thin films are having promising properties such as high visible transmittance and low electric resistivity, makes them very important transparent conductor in a variety of optoelectronics devices. Further, doping with pentavalent impurity such as Antimony (Sb enhances its conductivity considerably. In order to study the effect of Antimony doping, Antimony doped tin oxide (SnO2 : Sb thin films have been prepared by the co-evaporation of Sn and Sb using Plasma Assisted Thermal Evaporation (PATE in oxygen (O2 partial pressure at various doping level from 4% to 25%. The influence of various Sb doping levels on the compositional, electrical, optical and structural properties have been investigated using Energy Dispersive X-ray (EDX spectroscopy, Ultraviolet-Visible (UV-VIS transmission spectroscopy, four-probe resistivity measurement and X-ray Diffraction (XRD, respectively. EDX studies confirmed the different Sb doping levels in the grown films from 4 % to 25 %, while electrical resistivity is obtained in range of 0.36 to 9.5 Ohmcm using four-probe setup for 4 % to 25 % Sb doping levels. Transmittance spectra measured in UV-VIS range for Sb doped films show reduction in an average transmittance in respect to increase in Sb doping levels in the grown films. Whereas, XRD analysis reveals that higher Sb doping of 25 % induce the precipitation of antimony oxide (Sb2O3 phase and its precipitation suppressed the growth of SnO2 peaks as well as responsible for reduction in conductivity and transparency. The best electrical resistivity of optimized SnO2 : Sb (5 % is 0.36 Ohmcm without deteriorating the high (~ 80 % average transmittance in the wavelength region 300-800 nm in comparison to undoped SnO2 film (6.57 Ohmcm , confirm the usefulness of SnO2 : Sb (5 % films for device applications.

  17. Electronic structure, structural and optical properties of thermally evaporated CdTe thin films

    International Nuclear Information System (INIS)

    Thin films of CdTe were deposited on glass substrates by thermal evaporation. From the XRD measurements it is found that the films are of zinc-blende-type structure. The lattice parameter was determined as a=6.529A, which is larger than 6.48A of the powder sample, because the recrystallized lattice of the grown films is subjected to a compressive stress aroused as a result of the lattice mismatch and/or differences in thermal expansion coefficient between the CdTe and the underlying substrate. Transmittance, absorption, extinction and refractive coefficients are measured. Electronic structure, band parameters and optical spectra of CdTe were calculated from ab initio studies within the LDA and LDA+U approximations. It is shown that LDA underestimates the band gap, energy levels of the Cd-4d states, s-d coupling and band dispersion. However, it calculates the spin-orbit coupling correctly. LDA+U did not increase much the band gap value, but it corrected the s-d coupling by shifting the Cd-4d levels towards the experimentally determined location and by splitting the LDA-derived single s peak into two peaks, which originates from admixture of s and d states. It is shown that the s-d coupling plays an important role in absorption and reflectivity constants. The calculated optical spectra fairly agree with experimental data. Independent of wave vector scissors operator is found to be a good first approximation to shift rigidly the band gap of CdTe underestimated by LDA

  18. Characterization of Ta{2}O{5} thin films prepared by reactive evaporation

    Science.gov (United States)

    Asghar, M. H.; Placido, F.; Naseem, S.

    2006-11-01

    Reactively evaporated thin films of tantalum oxide are prepared on glass substrate, using electron beam heating, for optical applications. Firstly, the deposition was carried out at 0.20 nm/s, with substrate temperature of 200 circC, and oxygen flow rate was varied from 0.0 to 30.0 sccm to study the effect of flow rate on optical constants. The optical constants evaluated by using transmission data of the samples, with curve fitting, show a strong dependence on oxygen flow rate. Oxygen flow rate of 10.0 sccm has been found to give reasonably high index (n:2.11 at λ =500 nm) and low absorption of the order of 10-3 in most part of the desired spectrum (380 850 nm). However, for oxygen flow rates below 10.0 sccm and above 20.0 sccm the films have exhibited low index and comparatively high absorption. In the next step, deposition rates were varied from 0.10 0.30 nm/s with steps of 0.01, keeping oxygen flow rate and substrate temperature constant at 10.0 sccm and 200 circC respectively, to optimize the film properties. A variation in refractive index and extinction coefficient values is observed with varying deposition rates. An increase in refractive index (n:2.125 at λ =500 nm) with reduced absorption (“k” of the order of 10-4) is achieved over the entire spectrum for the film deposited at 0.10 nm/s. The film was found to be highly adherent to the substrate as revealed by qualitative adhesive tape peel test. Keeping in view the application of the work, calculation of optical constants was extended up to 1100 nm for the sample deposited at 0.10 nm/s. The results have shown nearly constant optical constant values over the extended range making the film useful over a broad spectral region. AFM studies show that the surface is extremely smooth and compact, giving average and rms roughness values of 5.51 and 7.174 Å respectively, for the studied area of 2.5 μ ×2.5 μ. XRD and SEM studies carried out for structural analysis show that the film is generally amorphous

  19. Structural and magnetic properties of SmCo-based magnetic films grown by electron-beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, P., E-mail: psdrdo@gmail.com [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Vinod, V.T.P.; Černík, Miroslav [Institute for Nanomaterials, Advanced Technologies and Innovation, Department of Natural Sciences, Technical University of Liberec, Studentská 1402/2, Liberec 1, 461 17 (Czech Republic); Vishnuraj, R.; Arout Chelvane, J.; Kamat, S.V. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Hsu, Jen-Hwa, E-mail: jhhsu@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China)

    2015-07-01

    Sub-micron thick Sm–Co films (200 and 300 nm) with selective phase composition are grown on Si (100) substrates by electron-beam evaporation using Sm-lean alloy targets such as Sm{sub 4}Co{sub 96} and Sm{sub 8}Co{sub 92}. The structural and magnetic properties of Sm–Co films are characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and super-conducting quantum interference device (SQUID) magnetometer. The Sm–Co films obtained with the Sm{sub 4}Co{sub 96} target exhibit Sm{sub 2}Co{sub 17} as a prominent phase; while the films produced with the Sm{sub 8}Co{sub 92} target show Sm{sub 2}Co{sub 7} as a major phase. Both the Sm–Co films reveal granular morphology; however, the estimated grain size values are slightly lower in the case of Sm{sub 2}Co{sub 7} films, irrespective of their thicknesses. Coercivity (H{sub c}) values of 1.48 and 0.9 kOe are achieved for the as-grown 200-nm thick Sm{sub 2}Co{sub 17} and Sm{sub 2}Co{sub 7}-films. Temperature-dependent magnetization studies confirm that the demagnetization behaviors of these films are consistent with respect to the identified phase composition. Upon rapid thermal annealing, maximum H{sub c} value of 8.4 kOe is achieved for the 200 nm thick Sm{sub 2}Co{sub 17}-films. As far as e-beam evaporated Sm–Co films are concerned, this H{sub c} value is one of the best values reported so far. - Highlights: • Electron-beam evaporation was exploited to grow sub-μm thick Sm–Co films. • Sm{sub 2}Co{sub 7} and Sm{sub 2}Co{sub 17} magnetic phases were crystallized using Sm-lean alloy targets. • Both 200 and 300-nm thick Sm–Co films revealed distinct granular morphology. • Sm–Co films of lower thickness exhibited high H{sub c} and low M{sub s} and vice-versa. • Coercivity value of 8.4 kOe achieved for the 200-nm thick Sm{sub 2}Co{sub 17}-films after RTA.

  20. A study on the nonlinear microwave electrodynamic response of e-beam evaporated MgB2 superconducting thin films

    International Nuclear Information System (INIS)

    We present a study on the temperature and field dependence of the microwave surface impedance Zs in thin films of the superconducting MgB2 compound. Samples were prepared by e-beam evaporation of boron on r-plane sapphire followed by an ex situ annealing in Mg vapour. Critical temperature values range between 26 and 38 K. Surface impedance measurements (Zs = Rs + iXs) were performed from 2 K close to Tc in the microwave region up to 20 GHz via parallel plate or dielectrically loaded resonators in 'symmetric' (two MgB2 films) and asymmetric (an MgB2 film and a commercial YBCO control film) configurations. At high microwave power, frequency domain measurements show a characteristic signature associated with weak links and this appears to be the limiting factor governing the performance of these films

  1. A study on the nonlinear microwave electrodynamic response of e-beam evaporated MgB2 superconducting thin films

    Science.gov (United States)

    Andreone, A.; Di Gennaro, E.; Lamura, G.; Salluzzo, M.; Purnell, A.; Cohen, L. F.; Hao, L.; Gallop, J.; Cantoni, C.; Paranthaman, M.

    2003-02-01

    We present a study on the temperature and field dependence of the microwave surface impedance Zs in thin films of the superconducting MgB2 compound. Samples were prepared by e-beam evaporation of boron on r-plane sapphire followed by an ex situ annealing in Mg vapour. Critical temperature values range between 26 and 38 K. Surface impedance measurements (Zs = Rs + iXs) were performed from 2 K close to Tc in the microwave region up to 20 GHz via parallel plate or dielectrically loaded resonators in 'symmetric' (two MgB2 films) and asymmetric (an MgB2 film and a commercial YBCO control film) configurations. At high microwave power, frequency domain measurements show a characteristic signature associated with weak links and this appears to be the limiting factor governing the performance of these films.

  2. The effect of oxygen flow rate on refractive index of aluminum oxide film deposited by electron beam evaporation technique

    Directory of Open Access Journals (Sweden)

    R Shakouri

    2016-02-01

    Full Text Available The effects of oxygen flow rate on refractive index of aluminum oxide film have been investigated. The Al2O3 films are deposited by electron beam on glass substrate at different oxygen flow rates. The substrate was heated to reach  and the temperature was constant during the thin film growth. The transmittance spectrum of samples was recorded in the wavelength 400-800 nm.  Then, using the maxima and minima of transmittance the refractive index and the extinction coefficient of samples were determined. It has been found that if we reduce the oxygen flow, while the evaporation rate is kept constant, the refractive index of Al2O3 films increases. On the other hand, reduced oxygen pressure causes the Al2O3 films to have some absorption.

  3. Optical and Morphological Studies of Thermally Evaporated PTCDI-C8 Thin Films for Organic Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Ronak Rahimi

    2013-01-01

    Full Text Available PTCDI-C8 due to its relatively high photosensitivity and high electron mobility has attracted much attention in organic semiconductor devices. In this work, thin films of PTCDI-C8 with different thicknesses were deposited on silicon substrates with native silicon dioxide using a vacuum thermal evaporator. Several material characterization techniques have been utilized to evaluate the structure, morphology, and optical properties of these films. Their optical constants (refractive index and extinction coefficient have been extracted from the spectroscopic ellipsometry (SE. X-ray reflectivity (XRR and atomic force microscopy (AFM were employed to determine the morphology and structure as well as the thickness and roughness of the PTCDI-C8 thin films. These films revealed a high degree of structural ordering within the layers. All the experimental measurements were performed under ambient conditions. PTCDI-C8 films have shown to endure ambient condition which allows pots-deposition characterization.

  4. Impact of thermal annealing on optical properties of vacuum evaporated CdTe thin films for solar cells

    Science.gov (United States)

    Chander, Subhash; Purohit, A.; Lal, C.; Nehra, S. P.; Dhaka, M. S.

    2016-05-01

    In this paper, the impact of thermal annealing on optical properties of cadmium telluride (CdTe) thin films is investigated. The films of thickness 650 nm were deposited on thoroughly cleaned glass substrate employing vacuum evaporation followed by thermal annealing in the temperature range 250-450 °C. The as-deposited and annealed films were characterized using UV-Vis spectrophotometer. The optical band gap is found to be decreased from 1.88 eV to 1.48 eV with thermal annealing. The refractive index is found to be in the range 2.73-2.92 and observed to increase with annealing treatment. The experimental results reveal that the thermal annealing plays an important role to enhance the optical properties of CdTe thin films and annealed films may be used as absorber layer in CdTe/CdS solar cells.

  5. Microstructural, nanomechanical, and microtribological properties of Pb thin films prepared by pulsed laser deposition and thermal evaporation techniques

    International Nuclear Information System (INIS)

    In this work, the authors compare the morphological, structural, nanomechanical, and microtribological properties of Pb films deposited by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques onto Si (111) substrates. Films were investigated by scanning electron microscopy, surface probe microscopy, and x-ray diffraction in θ-2θ geometry to determine their morphology, root-mean-square (RMS) roughness, and microstructure, respectively. TE films showed a percolated morphology with densely packed fibrous grains while PLD films had a granular morphology with a columnar and tightly packed structure in accordance with the zone growth model of Thornton. Moreover, PLD films presented a more polycrystalline structure with respect to TE films, with RMS roughness of 14 and 10 nm, respectively. Hardness and elastic modulus vary from 2.1 to 0.8 GPa and from 14 to 10 GPa for PLD and TE films, respectively. A reciprocal friction test has shown that PLD films have lower friction coefficient and wear rate than TE films. Our study has demonstrated for first time that, at the microscale, Pb films do not show the same simple lubricious properties measured at the macroscale

  6. Microstructural, nanomechanical, and microtribological properties of Pb thin films prepared by pulsed laser deposition and thermal evaporation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Broitman, Esteban, E-mail: esbro@ifm.liu.se [Thin Film Physics Division, IFM, Linköping University, SE-581 83 Linköping (Sweden); Flores-Ruiz, Francisco J. [Thin Film Physics Division, IFM, Linköping University, SE-581 83 Linköping, Sweden and Centro de Investigación y de Estudios Avanzados del I.P.N., Unidad Querétaro, Querétaro 76230 (Mexico); Di Giulio, Massimo [Università del Salento, Dipartimento di Matematica e Fisica “E. De Giorgi”, 73100 Lecce (Italy); Gontad, Francisco; Lorusso, Antonella; Perrone, Alessio [Università del Salento, Dipartimento di Matematica e Fisica “E. De Giorgi”, 73100 Lecce, Italy and INFN-Istituto Nazionale di Fisica Nucleare, 73100 Lecce (Italy)

    2016-03-15

    In this work, the authors compare the morphological, structural, nanomechanical, and microtribological properties of Pb films deposited by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques onto Si (111) substrates. Films were investigated by scanning electron microscopy, surface probe microscopy, and x-ray diffraction in θ-2θ geometry to determine their morphology, root-mean-square (RMS) roughness, and microstructure, respectively. TE films showed a percolated morphology with densely packed fibrous grains while PLD films had a granular morphology with a columnar and tightly packed structure in accordance with the zone growth model of Thornton. Moreover, PLD films presented a more polycrystalline structure with respect to TE films, with RMS roughness of 14 and 10 nm, respectively. Hardness and elastic modulus vary from 2.1 to 0.8 GPa and from 14 to 10 GPa for PLD and TE films, respectively. A reciprocal friction test has shown that PLD films have lower friction coefficient and wear rate than TE films. Our study has demonstrated for first time that, at the microscale, Pb films do not show the same simple lubricious properties measured at the macroscale.

  7. Fabrication of multi-electrode array platforms for neuronal interfacing with bi-layer lift-off resist sputter deposition

    International Nuclear Information System (INIS)

    We report a bi-layer lift-off resist (LOR) technique in combination with sputter deposition of silicon dioxide (SiO2) as a new passivation method in the fabrication of a multi-electrode array (MEA). Using the photo-insensitive LOR as a sacrificial bottom layer and the negative photoresist as a patterning top layer, and performing low-temperature sputter deposition of SiO2 followed by lift-off, we could successfully fabricate damage-free indium-tin oxide (ITO) and Au MEA. The bi-layer LOR sputter deposition processed Au MEA showed an impedance value of 6 × 105 Ω (at 1 kHz), with good consistency over 60 electrodes. The passivation performance of the bi-layer LOR sputter-deposited SiO2 was tested by electrodepositing Au nanoparticles (NPs) on the Au electrode, resulting in the well-confined and uniformly coated Au NPs. The bi-layer LOR sputter deposition processed ITO, Au, and Au NP-modified MEAs were evaluated and found to have a neuronal spike recording capability at a single unit level, confirming the validity of the bi-layer LOR sputter deposition as an effective passivation technique in fabrication of a MEA. These results suggest that the damage-free Au MEA fabricated with bi-layer LOR sputter deposition would be a viable platform for screening surface modification techniques that are available in neuronal interfacing. (technical note)

  8. Numerical studies of temperature profile and hydrodynamic phenomena during excimer laser assisted heteroepitaxial growth of patterned silicon and germanium bi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati Roma (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-01-01

    In this manuscript, a 3-D axisymmetric model for the heteroepitaxial growth induced by irradiating thin patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers on Si (100) with pulsed UV-laser radiation, is presented. For reducing optimization steps, an efficient simulation of the laser induced processes that include rapid heating and solidification phenomena in the range of several tenth of nanoseconds, must be performed, if alloy composition and quality has to be adjusted. In this study, the effects of various laser energy densities on different amorphous Si/Ge bi-layer structures has been predicted and adjusted to obtain the desired Ge concentration profiles for applications as sacrificial layers, i.e. a Ge containing film buried under a Si rich surface layer. The numerical model includes the temperature dependent variations of the thermophysical properties and takes the coupled effects of temperature and hydrodynamic phenomena for a Boussinesq fluid, to estimate the element interdiffusion during the process and predicting the concentration profiles.

  9. Characterizations of the TiO{sub 2-x} films synthesized by e-beam evaporation for endovascular applications

    Energy Technology Data Exchange (ETDEWEB)

    Lin Zeng [Vacuum and Fluid Engineering Research Center, Northeastern University, Shenyang 110004 (China); Lee, In-Seop [Institute of Physics and Applied Physics, and Atomic-scale Surface Science Research Center, Yonsei University, Seoul 120-752 (Korea, Republic of); Choi, Yoon-Jeong; Noh, In-Sup [Department of Chemical Engineering, Seoul National University of Technology, Seoul 139-743 (Korea, Republic of); Chung, Sung-Min, E-mail: inseop@yonsei.ac.k [Implantium Implant Institute, Seoul 135-879 (Korea, Republic of)

    2009-02-15

    Different chemical states of titanium oxide films were deposited on commercially pure Ti (CP Ti) by electron-beam evaporation at different oxygen flow rates to examine a possibility of their applications to endovascular stents. The surface morphology, chemical composition and crystal structure of the obtained titanium oxide films were analyzed by FE-SEM, XPS and XRD, respectively. As a function of the deposition parameters employed, the obtained titanium oxide films demonstrated different mixtures of anatase phase, Ti{sub 2}O{sub 3} and TiO. By the formation of titanium oxide film on the CP Ti plate, the contact angle was decreased and the cellular activity of porcine aortic smooth muscle cells was increased. Post-deposition annealing was also found to be an important factor to achieve advantageous biocompatibility. When haemocompatibility was investigated by observing adhesion of blood platelets from platelet-rich plasma, less platelet adhesion was observed on titanium oxide films. These results indicated that titanium oxide film synthesized by e-beam evaporation could be applicable to coronary stents.

  10. Physical and electrochemical characterization of amorphous lithium lanthanum titanate solid electrolyte thin-film fabricated by e-beam evaporation

    International Nuclear Information System (INIS)

    Amorphous lithium lanthanum titanate (LLTO) solid electrolyte thin-films have been fabricated by e-beam evaporation. The effect of different e-beam power on the physical properties and electrical performance of LLTO thin-film is investigated. Higher e-beam power is a key factor to obtain good quality LLTO thin-film which has higher ionic conductivity. X-ray diffraction patterns, X-ray photoelectron spectra, scanning electron microscopy and impedance spectroscopy are used to characterize their physical and electrical properties. An all-solid-state of Li/LiPON/LLTO/LiCoO2 cell using LLTO thin-film as solid electrolyte exhibits the first discharge capacity of about 50 μA h/cm2-μm and the capacity fading is about 0.5% per cycles after 100 discharge-charge cycles at discharge current of 7 μA/cm2, demonstrating the promise of e-beam evaporation deposition for the fabrication of LLTO thin-film for all-solid-state thin-film rechargeable lithium batteries

  11. Physical and electrochemical characterization of amorphous lithium lanthanum titanate solid electrolyte thin-film fabricated by e-beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Li Chilin [Department of Chemistry and Laser Chemistry Institute, Shanghai Key laboratory of Molecular Catalysts and Innovative Materials, Fudan University, Shanghai, 200433 (China); Zhang Bin [Department of Chemistry and Laser Chemistry Institute, Shanghai Key laboratory of Molecular Catalysts and Innovative Materials, Fudan University, Shanghai, 200433 (China); Fu Zhengwen [Department of Chemistry and Laser Chemistry Institute, Shanghai Key laboratory of Molecular Catalysts and Innovative Materials, Fudan University, Shanghai, 200433 (China)]. E-mail: zhengwen@sh163.net

    2006-12-05

    Amorphous lithium lanthanum titanate (LLTO) solid electrolyte thin-films have been fabricated by e-beam evaporation. The effect of different e-beam power on the physical properties and electrical performance of LLTO thin-film is investigated. Higher e-beam power is a key factor to obtain good quality LLTO thin-film which has higher ionic conductivity. X-ray diffraction patterns, X-ray photoelectron spectra, scanning electron microscopy and impedance spectroscopy are used to characterize their physical and electrical properties. An all-solid-state of Li/LiPON/LLTO/LiCoO{sub 2} cell using LLTO thin-film as solid electrolyte exhibits the first discharge capacity of about 50 {mu}A h/cm{sup 2}-{mu}m and the capacity fading is about 0.5% per cycles after 100 discharge-charge cycles at discharge current of 7 {mu}A/cm{sup 2}, demonstrating the promise of e-beam evaporation deposition for the fabrication of LLTO thin-film for all-solid-state thin-film rechargeable lithium batteries.

  12. Structural characteristics of thermally evaporated Cu0.5Ag0.5InSe2 thin films

    Science.gov (United States)

    Gullu, H. H.; Parlak, M.

    2016-05-01

    In this work, Cu0.5Ag0.5InSe2 (CAIS) thin film samples were prepared by thermal evaporation of Cu, Ag, InSe and Se evaporants sequentially on glass substrates. Following the deposition, annealing processes were applied at different temperatures. The as-grown and annealed CAIS samples were nearly stoichiometric in the detection limit of the compositional measurement. The x-ray diffraction (XRD) measurements revealed that they were in polycrystalline structure with a preferred orientation along the (112) direction. Moreoever, the crystallinity of the films improved with increasing annealing temperature. According to the results of Raman measurements, the highest Raman intensity was found in the A1 mode which is directly proportional to the crystallinity of the samples. The surface properties of the thin films were analyzed by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM). These results showed that there was a Se agglomeration on the deposited film surfaces and with annealing processes segregation effects were observed on the surface of the annealed samples. X-ray photoelectron spectroscopy (XPS) measurements were carried out to get information about surface and near-surface properties of the films. The results from the surface and depth surface analyses of the films were found to be in agreement with the energy dispersive spectroscopy (EDS) analysis.

  13. Heat transfer for falling film evaporation of industrially relevant fluids up to very high Prandtl numbers

    Science.gov (United States)

    Gourdon, Mathias; Karlsson, Erik; Innings, Fredrik; Jongsma, Alfred; Vamling, Lennart

    2016-02-01

    In many industrial applications, falling film evaporation is an attractive technique for solvent removal due to high heat transfer and low residence times. Examples are the powder production in the dairy industry and in kraft pulp production process to remove water from so called black liquor. Common for both applications is that the fluids exhibit high viscosities in industrial practice. In this paper, results from experimental studies on both black liquor and a dairy product are reported for Prandtl numbers up to 800. The results are compared with several existing correlation in literature, and the need for a modified correlation is recognized especially to cover higher Prandtl-numbers. The following correlation for the turbulent flow region with 3 < Pr < 800 was derived from the data: {Nu}t = 0.0085 \\cdot Re^{0.2} \\cdot {Pr^{0.65}} The correlation has been compared to literature data from one additional study on two other fluids (propylene glycol and cyclohexanol) with fairly high Prandtl-numbers, from 40 to 58 and from 45 to 155 respectively and the agreement was within ±40 %.

  14. Surface functionalization of cyclic olefin copolymer (COC) with evaporated TiO2 thin film

    Science.gov (United States)

    El Fissi, Lamia; Vandormael, Denis; Houssiau, Laurent; Francis, Laurent A.

    2016-02-01

    Cyclic olefin copolymer (COC) is a new class of thermoplastic polymers used for a variety of applications ranging from bio-sensing to optics. However, the hydrophobicity of native COC hampers the further development and application of this material [1]. In this work, we report the structural, morphological, and optical properties of the TiO2/COC hybrid material, which provides a desirable substrate for optical devices and subsequent surface modifications. The TiO2 film on COC substrate was deposited by the evaporation method, and it was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), profilometry and atomic force microscope (AFM). Using an UV-vis spectrophotometer, we found that the transmittance of the TiO2/COC hybrid material in the visible domain reached 80%. The TiO2/COC hybrid appeared to be stable in most of the assessed polar solvents and acid/basic solutions. The new TiO2/COC hybrid material and the robust fabrication method are expected to enable a variety of BioMEMS applications.

  15. Oxidation behavior of arc evaporated Al-Cr-Si-N thin films

    International Nuclear Information System (INIS)

    The impact of Al and Si on the oxidation behavior of Al-Cr-(Si)-N thin films synthesized by arc evaporation of powder metallurgically prepared AlxCr1−x targets with x = Al/(Al + Cr) of 0.5, 0.6, and 0.7 and (Al0.5Cr0.5)1−zSiz targets with Si contents of z = 0.05, 0.1, and 0.2 in N2 atmosphere was studied in detail by means of differential scanning calorimetry, thermogravimetric analysis (TGA), x-ray diffraction, and Raman spectroscopy. Dynamical measurements in synthetic air (up to 1440 °C) revealed the highest onset temperature of pronounced oxidation for nitride coatings prepared from the Al0.4Cr0.4Si0.2 target. Isothermal TGA at 1100, 1200, 1250, and 1300 °C highlight the pronounced improvement of the oxidation resistance of AlxCr1−xN coatings by the addition of Si. The results show that Si promotes the formation of a dense coating morphology as well as a dense oxide scale when exposed to air.

  16. Dewatering of liquid radioactive wastes in thin-film rotary evaporators

    International Nuclear Information System (INIS)

    A sizable amount of liquid radioactive waste of different levels of radioactivity is formed during the operation of an atomic power plant and during reprocessing of spent nuclear fuel. Current concepts for handling such wastes require reliable isolation of them from the biosphere. At present, bituminization and cementation for medium- and low-level liquid radioactive waste and vitrification for high- and perhaps medium-level liquid radioactive waste are considered promising methods of waste disposal. Solidification can be implemented in a one- or a two-stage process. In the one-stage process, liquid radioactive wastes are fed together with glass-forming additives into a melter (an electric furnace, a crucible furnace, etc.), where they are successively put through dewatering, calcination, and melting with the formation of glassy materials. Implementation of the two-stage process leads to some complication of the process flow diagram, but allows a reduction of the dimensions of basic equipment and makes possible remote replacement and repair of the equipment. The object of this work was to study the possibility of using a thin-film rotary evaporator in the first stage of the liquid radioactive waste solidification process (bituminization, cementation, vitrification), to give an evaluation of the effect of process parameters on process stability and on the physical and chemical characteristics of the concentrates produced

  17. Impact of thermal annealing on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

    Science.gov (United States)

    Chander, Subhash; Dhaka, M. S.

    2016-06-01

    A study on impact of post-deposition thermal annealing on the physical properties of CdTe thin films is undertaken in this paper. The thin films of thickness 500 nm were grown on ITO and glass substrates employing thermal vacuum evaporation followed by post-deposition thermal annealing in air atmosphere within low temperature range 150-350 °C. These films were subjected to the XRD, UV-Vis NIR spectrophotometer, source meter, SEM coupled with EDS and AFM for structural, optical, electrical and surface topographical analysis respectively. The diffraction patterns reveal that the films are having zinc-blende cubic structure with preferred orientation along (111) and polycrystalline in nature. The crystallographic parameters are calculated and discussed in detail. The optical band gap is found in the range 1.48-1.64 eV and observed to decrease with thermal annealing. The current-voltage characteristics show that the CdTe films exhibit linear ohmic behavior. The SEM studies show that the as-grown films are homogeneous, uniform and free from defects. The AFM studies reveal that the surface roughness of films is observed to increase with annealing. The experimental results reveal that the thermal annealing has significant impact on the physical properties of CdTe thin films and may be used as absorber layer to the CdTe/CdS thin films solar cells.

  18. Analytical Solutions of Heat Transfer and Film Thickness with Slip Condition Effect in Thin-Film Evaporation for Two-Phase Flow in Microchannel

    Directory of Open Access Journals (Sweden)

    Ahmed Jassim Shkarah

    2015-01-01

    Full Text Available Physical and mathematical model has been developed to predict the two-phase flow and heat transfer in a microchannel with evaporative heat transfer. Sample solutions to the model were obtained for both analytical analysis and numerical analysis. It is assumed that the capillary pressure is neglected (Morris, 2003. Results are provided for liquid film thickness, total heat flux, and evaporating heat flux distribution. In addition to the sample calculations that were used to illustrate the transport characteristics, computations based on the current model were performed to generate results for comparisons with the analytical results of Wang et al. (2008 and Wayner Jr. et al. (1976. The calculated results from the current model match closely with those of analytical results of Wang et al. (2008 and Wayner Jr. et al. (1976. This work will lead to a better understanding of heat transfer and fluid flow occurring in the evaporating film region and develop an analytical equation for evaporating liquid film thickness.

  19. Silver nano-particles in fluoride films fabricated by Pulsed Laser Deposition with auxiliary Electron Beam Evaporation

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Lančok, Ján; Bulíř, Jiří; Hruška, Petr; Fekete, Ladislav; Fitl, Přemysl

    Strasbourg: European Materials Research Society, 2013. [E- MRS 2013 Spring Meeting. 27.05.2013-31.05.2013, Strasbourg] R&D Projects: GA MŠk(CZ) 7AMB12FR034; GA ČR(CZ) GAP108/11/1312 Grant ostatní: AVČR(CZ) M100101271 Institutional support: RVO:68378271 Keywords : lanthanum fluoride * calcium fluoride * thin film * silver nanoparticles * pulsed laser deposition * electron beam evaporation Subject RIV: BM - Solid Matter Physics ; Magnetism

  20. A comparison of properties of phthalocyanine thin films prepared by organic molecular evaporation and pulsed laser deposition

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Fitl, P.; Bensalah-Ledoux, A.; Guy, S.; Bulíř, Jiří; Fekete, Ladislav; Náhlík, J.; Marešová, E.; Moine, B.; Lančok, Ján; Vrňata, M.

    Lille: European Materials Research Society, 2014 - (Lippert, T.). DD-14-DD-14 [E- MRS 2014 Spring Meeting. 26.05.2014-30.05.2014, Lille] R&D Projects: GA ČR(CZ) GAP108/11/1298; GA ČR(CZ) GA14-10279S; GA MŠk(CZ) 7AMB14FR010 Institutional support: RVO:68378271 Keywords : phthalocyanine * thin films * organic molecular evaporation * pulsed laser deposition Subject RIV: BM - Solid Matter Physics ; Magnetism

  1. Electrical properties and surface morphology of electron beam evaporated p-type silicon thin films on polyethylene terephthalate for solar cells applications

    Energy Technology Data Exchange (ETDEWEB)

    Ang, P. C.; Ibrahim, K.; Pakhuruddin, M. Z. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, Minden 11800 Penang (Malaysia)

    2015-04-24

    One way to realize low-cost thin film silicon (Si) solar cells fabrication is by depositing the films with high-deposition rate and manufacturing-compatible electron beam (e-beam) evaporation onto inexpensive foreign substrates such as glass or plastic. Most of the ongoing research is reported on e-beam evaporation of Si films on glass substrates to make polycrystalline solar cells but works combining both e-beam evaporation and plastic substrates are still scarce in the literature. This paper studies electrical properties and surface morphology of 1 µm electron beam evaporated Al-doped p-type silicon thin films on textured polyethylene terephthalate (PET) substrate for application as an absorber layer in solar cells. In this work, Si thin films with different doping concentrations (including an undoped reference) are prepared by e-beam evaporation. Energy dispersion X-ray (EDX) showed that the Si films are uniformly doped by Al dopant atoms. With increased Al/Si ratio, doping concentration increased while both resistivity and carrier mobility of the films showed opposite relationships. Root mean square (RMS) surface roughness increased. Overall, the Al-doped Si film with Al/Si ratio of 2% (doping concentration = 1.57×10{sup 16} atoms/cm{sup 3}) has been found to provide the optimum properties of a p-type absorber layer for fabrication of thin film Si solar cells on PET substrate.

  2. High fluence deposition of polyethylene glycol films at 1064 nm by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Purice, Andreea; Schou, Jørgen; Kingshott, P.; Pryds, Nini; Dinescu, M.

    2007-01-01

    microbalance. The laser fluence needed to produce PEG films turned out to be unexpectedly high with a threshold of 9 J/cm(2) and the deposition rate was much lower than that with laser light at 355 nm. Results from matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI......Matrix assisted pulsed laser evaporation (MAPLE) has been applied for deposition of thin polyethylene glycol (PEG) films with infrared laser light at 1064 nm. We have irradiated frozen targets (of 1 wt.% PEG dissolved in water) and measured the deposition rate in situ with a quartz crystal 2...

  3. Optical Properties and Microstructure of Ta2O5 Thin Films Prepared by Ion Assisted Electron Beam Evaporation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guangyong; XUE Yiyu; GUO Peitao; WANG Hanhua; MA Zhongjie

    2008-01-01

    An effective method for determining the refractive index of weak absorption transparent thin films was presented, which is also applicable to other weak absorption dielectric thin films.The as-deposited Ta2O5 thin films prepared by ion assisted electron beam evaporation showed a maxima transmittance as high as 93% which was close to that of the bare substrate, and exhibited a blue shift when the substrate temperature increased from room temperature to 250 ℃. The refractive index seemed to be immune to the substrate temperature and film thickness with its value about 2.14 at incidence wavelength of 550 nm. The surface morphology measured by atomic force microscopy (AFM) revealed that the microstructures lead to the slim optical difference, which was the interplay of substrate temperature and assisted ion beam.

  4. Growth Structural and Optical Properties of the Thermally Evaporated Tin Diselenide (SnSe2 Thin Films

    Directory of Open Access Journals (Sweden)

    R. Sachdeva1,

    2011-01-01

    Full Text Available Tin diselenide (SnSe2 compound was prepared by melt-quenching technique from its constituent elements. The phase structure and composition of the chemical constituents present in the bulk has been determined using X-ray diffraction (XRD and energy dispersion X-ray analysis (EDAX respectively. SnSe2 thin films were grown using direct thermal evaporation of SnSe2 compound material on chemically cleaned glass substrate, which were held at different substrate temperatures. X-ray diffraction and Scanning Electron Microscopy (SEM were used to examine structure and surface morphology of the films. The investigations show that the films grown above 150 °C are single phase and polycrystalline in nature. VIS-IR Spectra of the films were recorded in the wavelength range 380 nm to 1300 nm. The data has been analyzed to find optical parameters like absorption coefficient and energy bandgap.

  5. Azo-derivatives thin films grown by matrix-assisted pulsed laser evaporation for non-linear optical applications

    International Nuclear Information System (INIS)

    Azo-dye compounds, in bulk or as thin films, are extensively studied due to their particular optical properties. These properties include non-linear interaction, e.g. two-photon absorption, optical limiting and all-optical poling, with potential applications in optoelectronics and sensors development. Herein, we report on the deposition of pyrazolone derivatives, namely 1-phenyl-3-methyl-4-(1′-azo-2′-sodium carboxylate)-pyrazole-5-one thin films, for applications in second harmonic generation. Matrix-assisted pulsed laser evaporation was employed for layers growth, using a Nd:YAG device operating at 266 nm (4ω). The structure and surface morphology of the deposited films were examined by Fourier transform infrared spectroscopy, atomic force microscopy, and scanning electron microscopy. Spectroscopic-ellipsometry was employed to investigate thin film optical properties. Significant second harmonic generation capabilities of the compound were pointed out by using a femtosecond Ti:sapphire laser.

  6. Experimental investigation of nucleate boiling and thin-film evaporation on enhanced silicon surfaces

    Science.gov (United States)

    Malla, Shailesh

    The present work consists of two major studies. The first study investigates the effects of surface energy or wettability on nucleate pool boiling and the second study investigates the thin-film evaporative cooling for near junction thermal management. For the first study, effects of surface energy or wettability on critical heat flux (CHF) and boiling heat transfer (BHT) of smooth heated surfaces was studied in saturated pool boiling of water at 1 atm. For this purpose hydrophilic and hydrophobic surfaces were created on one side of 1cm x 1cm double-side polished silicon substrates. A resistive heating layer was applied on the opposite side of each substrate. The surface energies of the created surfaces were characterized by measuring the static contact angles of water sessile drops. To provide a wide range of surface energies, surfaces were made of Teflon (hydrophobic), bare silicon (hydrophilic) and aluminum oxide (most hydrophilic). The measured contact angles on these surfaces were ˜108, ˜57 and ˜13 degrees respectively. The results of pool boiling tests on these surfaces clearly illustrate the connection between surface energy and CHF. CHF was shown to linearly decrease with contact angle increase, from ˜125 W/cm2 on aluminum oxide (most hydrophilic) to nearly one tenth of this value on Teflon (hydrophobic). The most hydrophilic surface also produced increasingly better BHT than plain silicon and Teflon as heat flux increased. However, below ˜5 W/cm2 the hydrophobic surface demonstrated better heat transfer due to earlier onset of nucleate boiling, reducing surface superheats by up to ˜5 degrees relative to the other two surfaces. Above ˜5 W/cm2 the BHT of the hydrophobic surface rapidly deteriorated as superheat increased towards the value at CHF. To further understand the effect of surface energy on pool boiling performance, the growth and departure of bubbles from single nucleating sites on each surface were analyzed from high-speed video recordings

  7. Schottky barriers based on n-In2S3 films obtained by laser-induced evaporation

    International Nuclear Information System (INIS)

    The method of evaporation of starting targets with subsequent deposition onto glass substrates at temperatures of 480-720 K is used to grow homogeneous thin (0.6-1.5 μm) n-In2S3 films on which the In/n-In2S3 Schottky barriers were formed for the first time; evaporation was induced by a pulsed laser. The temperature dependence of resistivity of the films with the n-type conductivity was studied and the activation energy of donor centers in these films was determined. Spectral dependences of the photoconversion quantum efficiency η(ℎω) for the barriers obtained were studied. An analysis of the spectral dependences η(ℎω) made it possible to identify the type of band-to-band transitions and estimate the band gap in the In2S3 films. It is concluded that the thin In2S3 films can be used in broadband photoconverters of optical radiation

  8. Experimental investigation of evaporation and condensation in the contact line region of a thin liquid film experiencing small thermal perturbations.

    Science.gov (United States)

    Argade, Rajendra; Ghosh, Sombuddha; De, Sirshendu; DasGupta, Sunando

    2007-01-30

    Image-analyzing interferometry technique is successfully used to study microscale transport processes related to a curved microfilm on a solid substrate. Digital image processing is used to analyze the images of interference fringes, leading to the evaluation of liquid (heptane) film thickness and curvature profiles at different inclinations on a high refractive index glass surface. The curvature profiles obtained at different inclinations clearly demonstrate that there is a maximum in curvature near the junction of the adsorbed film (of uniform thickness) and the curved film, and then it becomes constant in the thicker portions of the film. The adsorbed film thickness is measured for horizontal as well as inclined positions. Experimentally obtained values of the dispersion constants are compared to those predicted from the Dzyaloshinskii-Lifshitz-Pitaevskii (DLP) theory, and reasonable agreements were obtained. A parameter alpha is defined and experimentally evaluated to quantify the closeness of the system to equilibrium. The nonequilibrium behavior of this parameter alpha is also observed with certain heat input at a particular inclination. A small thermal perturbation is used to force the liquid meniscus to undergo a cycle of alternating condensation and evaporation. High-speed video-microscopy and subsequent image analysis are used for data analysis. The numerical solution of a model that takes into account the balance between the suction and the capillary force is compared with the data to elicit new insights into the evaporation/condensation phenomena and to estimate the interfacial temperature differences for near-equilibrium situations. PMID:17241038

  9. Congruent evaporation and epitaxy in thin film laser ablation deposition (LAD) of rare earth transition metal elements and compounds

    International Nuclear Information System (INIS)

    This paper reports that laser ablation deposition (LAD) is a versatile thin film preparation technique which has been slowly developing for a number of years, and is currently receiving a lot of attention as demand increasingly exploits its advantages over other established techniques. Apart from its simplicity, one of its main advantages is the possibility of congruently evaporating any solid compound target, be it metal or insulator, due to the extremely high energy and instantaneous power densities attainable with pulsed lasers (up to 50 Jcm-2 and 1012 Wcm-2 for picosecond pulses). In this paper, we report on tests for both congruent evaporation in LAD of a number of rate earth -- transition metal intermetallic compounds including Nd2Fe13B, YZn0.7, YNi3, Y2Fe15 and YNi5 for different preparation conditions (using a Nd:YAG laser λ = 1064, 532, 355 nm, τ = 35 ps and 20 ns) and on the epitaxial growth of YNi5 and W on monocrystalline sapphire substrates. Optical and electron microscopy were used to examine film morphology while congruent evaporation was confirmed using x-ray microprobe analysis. In-situ RHEED revealed good epitax of the films deposited on sapphire, with the hexagonal diffraction patterns obtained for YNi5 being identical to those of an YNi5 reference single crystal

  10. Sintering of bi-layered porous structures: Stress development and shape evolution

    DEFF Research Database (Denmark)

    Ni, De Wei; Esposito, Vincenzo; Ramousse, Severine; Pryds, Nini

    Ce0.9Gd0.1O1.95 (CGO) and (La, Sr)MnO3 (LSM) are electro-ceramics materials with high potential for several electrochemical applications such as solid Oxide Fuel Cell (SOFC), gas separation membranes, and flue gas purification application. In the latter case, these materials are shaped as thick...... porous layers and sintered by co-firing process. In this work, porous CGO and LSM/CGO single layers were prepared by tape casting, and CGO-LSM/CGO bi-layer structures were obtained by lamination. The shrinkage characteristics of individual layers were measured by optical dilatometry and the uniaxial...

  11. Multi-scale modeling of shape distortions during sintering of bi-layers

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Bjørk, Rasmus; Olevsky, Eugene;

    2014-01-01

    theories like the continuum theory of sintering. A new multi-scale numerical approach for modeling of shape distortions during sintering of macroscopically inhomogeneous structures combined with a microstructure model is developed. The microstructures of the porous body are described by unit cells based on...... unit cells simulated by the kMC model. Examples of simulation of sintering of bi-layers based on different material systems are presented to illustrate the multi-scale model. The approach can be considered as an extension to the continuum theory of sintering combined with the meso-scale kinetic Monte...

  12. Bulk waves excited by a laser line pulse in a bi-layer cylinder

    Science.gov (United States)

    Pan, Y.; Chigarev, N.; Audoin, B.

    2010-03-01

    In this paper, the transient displacement excited by a laser line source is calculated for a bi-layer cylinder made of homogeneous and isotropic materials. A sample made by welding tin in a copper tube and a sample of cooper rod are considered. Experimental displacements are observed by the laser ultrasonic technique, and corresponding theoretical waveforms are calculated. Good agreement is found in the arrival time, shape and relative amplitude of various longitudinal and shear bulk waves propagating through the sample or reflected by the interface.

  13. Growth and characterization of ZnSxSe1-x films deposited by close-spaced evaporation

    International Nuclear Information System (INIS)

    Polycrystalline thin films of ZnSxSe1-x with x = 0, 0.25, 0.5, 0.75 and 1.0 have been synthesized using close-spaced evaporation. The films were deposited onto glass substrates at different substrate temperatures in the range 200-400 deg. C. The grown films were characterized using XRD, AFM, EDAX and UV-Vis-NIR spectrophotometer to determine the microstructural properties, composition and optical behaviour. All the ZnSxSe1-x films deposited between 275 and 300 deg. C were crystallized in cubic structure with a single peak that corresponds to the (1 1 1) plane as the preferred orientation. The composition analysis revealed that the films deposited at Ts = 275-325 deg. C were nearly stoichiometric. The average surface roughness for ZnSxSe1-x films deposited at 300 deg. C varied in the range 2-6 nm. The films were highly transparent with optical transmittance >85%. The evaluated energy band gap of the films increased with the increase of sulfur content in the layers and it varied in the range 2.61-3.60 eV. All the layers showed n-type electrical conductivity. The temperature dependence of conductivity was also studied and the activation energy values were evaluated

  14. Electron beam flash evaporation for YBaCuO and BiCaSrCuO thin films

    International Nuclear Information System (INIS)

    An electron beam flash evaporation technique is described which reproduces the stoichiometry of superconducting YBa2Cu3Ox (123), Bi2CaSr2Cu2Oy (2122), and Bi2Ca2Sr2Cu3Oz (2223) source powders. Films of each material deposited with this technique exhibit zero resistance temperatures of 78 K or above when furnace annealed; 75 K zero temperatures are obtained for 123 films in situ annealed with atomic oxygen at 775 degree C. Transport critical current densities are 1x104 A/cm2 in 25-μm stripes patterned from 123 films, and 6x104 A/cm2 in 1-mm stripes of 2122 and 2223 films using a 1-μV/mm measurement criteria. Typical normal state resistivities are 700 μΩ cm for 2122 and 2223 films and 5 mΩ cm for 123 films. The 2122 films are highly textured with the c axis normal to the substrate. All results are for films deposited on MgO

  15. Influence of thickness on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

    Science.gov (United States)

    Chander, Subhash; Dhaka, M. S.

    2016-02-01

    This paper presents the influence of thickness on physical properties of polycrystalline CdTe thin films. The thin films of thickness 450 nm, 650 nm and 850 nm were deposited employing thermal vacuum evaporation technique on glass and indium tin oxide (ITO) coated glass substrates. The physical properties of these as-grown thin films were investigated employing the X-ray diffraction (XRD), source meter, UV-Vis spectrophotometer, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The structural analysis reveals that the films have zinc-blende cubic structure and polycrystalline in nature with preferred orientation (111). The structural parameters like lattice constant, interplanar spacing, grain size, strain, dislocation density and number of crystallites per unit area are calculated. The average grain size and optical band gap are found in the range 15.16-21.22 nm and 1.44-1.63 eV respectively and observed to decrease with thickness. The current-voltage characteristics show that the electrical conductivity is observed to decrease with thickness. The surface morphology shows that films are free from crystal defects like pin holes and voids as well as homogeneous and uniform. The EDS patterns show the presence of cadmium and tellurium elements in the as grown films. The experimental results reveal that the film thickness plays significant role on the physical properties of as-grown CdTe thin films and higher thickness may be used as absorber layer to solar cells applications.

  16. Evaporate prediction and compensation of intake port wall-wetting fuel film for spark ignition engines fueled with ethanol-gasoline blends

    Institute of Scientific and Technical Information of China (English)

    Dong-wei YAO; Xin-chen LING; Feng WU

    2012-01-01

    The fuel dynamic transfer process,including fuel injection,fuel film deposition and evaporation in the intake port,was analyzed for spark ignition (SI) engines with port fuel injection (PFI).The influence of wall-wetting fuel film,especially its evaporation rate,upon the air-fuel ratio of in-cylinder mixtures was also discussed.According to the similarity principle,Fick's law,the ideal gas equation and the Gilliland correlation,an evaporate prediction model of wall-wetting fuel film was set up and an evaporate prediction based dynamic fuel film compensator was designed.Through engine cold start tests,the wall-wetting temperature,which is the key input of the fuel film evaporate prediction model,was also modeled and predicted.Combined with the experimental data of the evaporation characteristics of ethanol-gasoline blends and engine calibration tests,all the parameters of the wall-wetting fuel film evaporate prediction model used in the fuel film compensator were identified.Square-wave disturbance tests of fuel injection showed that with the help of the fuel film compensator the response of the in-cylinder air-fuel ratio was significantly improved and the real air-fuel ratio always closely matched the expected ratio.The fuel film compensator was then integrated into the final air-fuel ratio controller,and the engine tests showed that the air-fuel ratio control error was less than 2% in steady-state conditions,and less than 4%in transient conditions.The fuel film compensator also showed good adaptability to different ethanol-gasoline blends.

  17. Fatigue crack growth simulations of interfacial cracks in bi-layered FGMs using XFEM

    Science.gov (United States)

    Bhattacharya, S.; Singh, I. V.; Mishra, B. K.; Bui, T. Q.

    2013-10-01

    An investigation of fatigue crack growth of interfacial cracks in bi-layered materials using the extended finite element method is presented. The bi-material consists of two layers of dissimilar materials. The bottom layer is made of aluminium alloy while the upper one is made of functionally graded material (FGM). The FGM layer consists of 100 % aluminium alloy on the left side and 100 % ceramic (alumina) on the right side. The gradation in material property of the FGM layer is assumed to be exponential from the alloy side to the ceramic side. The domain based interaction integral approach is extended to obtain the stress intensity factors for an interfacial crack under thermo-mechanical load. The edge and centre cracks are taken at the interface of bi-layered material. The fatigue life of the interface crack plate is obtained using the Paris law of fatigue crack growth under cyclic mode-I, mixed-mode and thermal loads. This study reveals that the crack propagates into the FGM layer under all types of loads.

  18. Fabrication of patterned flexible graphene devices via facile direct transfer of as-grown bi-layer graphene

    International Nuclear Information System (INIS)

    Highlights: • Patterned bi-layer graphene was directly transferred onto various polymer substrates by using micro-contact printing technique. • Coating of dimethylformamide onto the polydimethylsiloxane (PDMS) stamp enhanced the adhesion between the bi-layer graphene and the PDMS stamp. • Patterned graphene devices showed mechanically stable electrical properties upon repeated bending cycles. - Abstract: We report on the fabrication of patterned flexible graphene devices via a facile direct transfer of bi-layer graphene grown on alumina (Al2O3) substrate, and the use of Ag nanowire stickers as flexible electrodes. Patterned polydimethylsiloxane (PDMS) stamps coated with vaporized dimethylformamide (DMF) are utilized to transfer as-grown graphene directly onto a flexible polyethylene terephthalate (PET) substrate. The facile direct transfer is attributed to the enhanced adhesion of the bi-layer graphene to PDMS, due to DMF-coating, as well as the weak adhesion between the bi-layer graphene and the Al2O3 substrate. In this way, flexible patterned graphene devices have been fabricated with Ag nanowire stickers as electrodes. Stable electrical conduction characteristics were measured over repetitive bending with a bending radius down to 5 mm

  19. Fabrication of patterned flexible graphene devices via facile direct transfer of as-grown bi-layer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Park, Heun; Kim, Kyung Hoon; Yoon, Jangyeol [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Kuk Ki; Park, Seung Min [Department of Chemistry, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Ha, Jeong Sook, E-mail: jeongsha@korea.ac.kr [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of); KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701 (Korea, Republic of)

    2015-02-15

    Highlights: • Patterned bi-layer graphene was directly transferred onto various polymer substrates by using micro-contact printing technique. • Coating of dimethylformamide onto the polydimethylsiloxane (PDMS) stamp enhanced the adhesion between the bi-layer graphene and the PDMS stamp. • Patterned graphene devices showed mechanically stable electrical properties upon repeated bending cycles. - Abstract: We report on the fabrication of patterned flexible graphene devices via a facile direct transfer of bi-layer graphene grown on alumina (Al{sub 2}O{sub 3}) substrate, and the use of Ag nanowire stickers as flexible electrodes. Patterned polydimethylsiloxane (PDMS) stamps coated with vaporized dimethylformamide (DMF) are utilized to transfer as-grown graphene directly onto a flexible polyethylene terephthalate (PET) substrate. The facile direct transfer is attributed to the enhanced adhesion of the bi-layer graphene to PDMS, due to DMF-coating, as well as the weak adhesion between the bi-layer graphene and the Al{sub 2}O{sub 3} substrate. In this way, flexible patterned graphene devices have been fabricated with Ag nanowire stickers as electrodes. Stable electrical conduction characteristics were measured over repetitive bending with a bending radius down to 5 mm.

  20. Growth and characterization of co-evaporated Cu2ZnSnSe4 thin films for photovoltaic applications

    International Nuclear Information System (INIS)

    Cu2ZnSnSe4 thin films are deposited using the four-source co-evaporation technique onto glass substrates held at 523, 573, 623 and 673 K and in situ annealed at 723 K for 1 h in a selenium atmosphere. XRD studies revealed that the films deposited at 523 and 573 K and annealed at 723 K contain ZnSe as a secondary phase. However, films deposited at 673 K and annealed at 723 K have Cu2-xSe as a secondary phase along with Cu2ZnSnSe4. Single phase, polycrystalline Cu2ZnSnSe4 films are obtained at a substrate temperature (Ts) of 623 K on in situ annealing at 723 K. The structure is found to be kesterite and the lattice parameters are a = 0.569 nm, c = 1.141 nm. The direct optical band gap of the films is found to lie between 1.42 and 1.57 eV for films deposited at different substrate temperatures. Electrical resistivity of the films is in the range 0.1-0.8 Ω cm depending on Ts.

  1. Room temperature growth of high crystalline quality Cu3N thin films by modified activated reactive evaporation

    International Nuclear Information System (INIS)

    Highlights: • Copper nitride (Cu3N) thin films have been prepared by a novel MARE technique • Highly crystalline Cu3N films were grown on glass substrates at room temperature • Preferential growth along a particular plane is mostly dependent on the RF power • Effect of deposition pressure and annealing on physical properties has been studied - Abstract: Highly crystalline copper nitride (Cu3N) thin films have been deposited on glass substrates at room temperature by a novel and commercially viable growth technique, known as modified activated reactive evaporation (MARE). The effects of change in radio frequency (RF) power and deposition pressure on the structural and optical properties of the films have been investigated. RF power plays a significant role for the preferential growth of these films along a particular plane whereas the deposition pressure has comparatively lesser impact on the same. However, the lattice parameter, film thickness and optical band gap are found to be strongly dependent on the deposition pressure. The MARE grown Cu3N films undergo complete decomposition into metallic Cu upon vacuum annealing at 400 °C which makes them promising candidates to be used in write once optical recording media

  2. Room temperature growth of high crystalline quality Cu{sub 3}N thin films by modified activated reactive evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Guruprasad, E-mail: guruprasad@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Meher, S.R. [School of Advanced Sciences, Vellore Institute of Technology University, Vellore 632014 (India); Jain, Mahaveer K. [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2015-01-15

    Highlights: • Copper nitride (Cu{sub 3}N) thin films have been prepared by a novel MARE technique • Highly crystalline Cu{sub 3}N films were grown on glass substrates at room temperature • Preferential growth along a particular plane is mostly dependent on the RF power • Effect of deposition pressure and annealing on physical properties has been studied - Abstract: Highly crystalline copper nitride (Cu{sub 3}N) thin films have been deposited on glass substrates at room temperature by a novel and commercially viable growth technique, known as modified activated reactive evaporation (MARE). The effects of change in radio frequency (RF) power and deposition pressure on the structural and optical properties of the films have been investigated. RF power plays a significant role for the preferential growth of these films along a particular plane whereas the deposition pressure has comparatively lesser impact on the same. However, the lattice parameter, film thickness and optical band gap are found to be strongly dependent on the deposition pressure. The MARE grown Cu{sub 3}N films undergo complete decomposition into metallic Cu upon vacuum annealing at 400 °C which makes them promising candidates to be used in write once optical recording media.

  3. Effects of Surface Roughness of Capillary Wall on the Profile of Thin Liquid Film and Evaporation Heat Transfer

    Institute of Scientific and Technical Information of China (English)

    Qu Wei; Ma Tongze

    2001-01-01

    The surface of capillary wall can be treated to have a periodic microrelief mathematically. The roughness is micro enough compared with the thickness of the liquid film. So, the surface roughness only exerts influence on the adsorptive potential. Macroscopically, the flow field of the liquid film can be considered as that when the rough surface has an equivalent smooth surface, whose position is at the crests of the microrelief. The mechanism of heat transfer is in connection with two resistances: the thermal resistance of the liquid film conduction and the thermal resistance of the interfacial evaporation. The capillary pressure between the two sides of the vapor-liquid interface due to the interfacial curvature and the disjoining pressure owing to the thin liquid film are considered simultaneously. Several micro tubes with different micro rough surfaces are studied. The length of the evaporating interfacial region decreases with the increase of roughness angle and/or the increase of the roughness height. The heat transfer coefficient and the temperature of the vapor-liquid interface will change to fit the constant mass flow rate.

  4. In6Se7 thin films by heating thermally evaporated indium and chemical bath deposited selenium multilayers

    International Nuclear Information System (INIS)

    Indium selenide (In6Se7) thin films were prepared via selenization of thermally evaporated indium thin films by dipping in sodium selenosulphate solution followed by annealing in nitrogen atmosphere. First, indium was thermally evaporated on glass substrate. Then, the indium coated glass substrates were dipped in a solution containing 80 ml 0.125 M sodium selenosulphate and 1.5 ml dilute acetic acid (25%) for 5 min. Glass/In-Se layers were annealed at 200-400 °C in nitrogen atmosphere (0.1 Torr) for 30 min. X-ray diffraction studies showed the formation of monoclinic In6Se7. Morphology of the thin films formed at different conditions was analyzed using Scanning electron microscopy. The elemental analysis was done using Energy dispersive X-ray detection. Electrical conductivity under dark and illumination conditions was evaluated. Optical band gap was computed using transmittance and reflectance spectra. The band gap value was in the range 1.8-2.6 eV corresponding to a direct allowed transition. We studied the effect of indium layer thickness and selenium deposition time on the structure, electrical and optical properties of In6Se7 thin films.

  5. Thickness dependence of dispersion parameters of the MoO{sub x} thin films prepared using the vacuum evaporation technique

    Energy Technology Data Exchange (ETDEWEB)

    Akın, Ümmühan, E-mail: uakin@selcuk.edu.tr; Şafak, Haluk

    2015-10-25

    The optical behaviors of molybdenum oxide thin films are highly important due to their widespread applications. In the present paper, the effect of thickness on the structure, morphology and optical properties of molybdenum oxide (MoO{sub x}) thin films prepared on Corning glass substrates using thermal evaporation technique was studied. The structure and morphology of films were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, while their optical properties were investigated by UV-VIS-NIR spectrophotometry in the spectral range from 300 to 2500 nm. It was observed that whole films have amorphous structure and also they showed rather high transmittance values reached nearly up to 90%. Absorption analysis showed two types of electronic transitions; both direct and indirect interband transition energy values of films decrease from 4.47 to 3.45 eV and from 3.00 to 2.75 eV, respectively, with increasing the film thickness, while the width of the localized states tail increases with thickness. This decrease in the band gap value can be attributed to the rising oxygen-ion vacancy densities with the thickness. The refractive indices of films were calculated from Sellmeier coefficients determined by nonlinear curve fitting method based on the measured transmittance spectral data. The dispersion of the refractive index was discussed in terms of the Wemple-DiDomenico single-oscillator model. The dispersion parameters such as average oscillator energy, E{sub o}, the dispersion energy, E{sub d}, and static refractive index n{sub o} were evaluated and they found to vary significantly with the film thickness. - Highlights: • MoO{sub x} thin films with different thickness were prepared using the vacuum evaporation technique. • The variation of fundamental absorption edge with the film thickness was determined. • A detailed dispersion analysis based on the Wemple-DiDomenico model was performed. • The dependence of all

  6. Analytical Modeling of a Loop Heat Pipe with a Flat Evaporator by Applying Thin-Film Theory

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Eui Guk [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Boo, Joon Hong [Korea Aerospace University, Goyang (Korea, Republic of)

    2010-12-15

    A steady-state analytical model was presented for a loop heat pipe (LHP) with an evaporator that has a flat geometry. On the basis of a series of reviews of the relevant literature, a sequence of calculations was proposed to predict the temperatures and pressures at each important part of the LHP: the evaporator, liquid reservoir (compensation chamber), liquid line, vapor line, and condenser. The analysis of the evaporator, which is the only part in the LHP that has a capillary structure, was emphasized. Thin-film theory is applied to account for the pressure and temperature in the region adjacent to the liquid-vapor interface in the evaporator. The present study introduced a unique method to estimate the liquid temperature at the interface. Relative freedom was assumed in the configuration of a condenser with a simplified liquid-vapor interface. Our steady-state model was validated by experimental results available in the literature. The relative error was within 3% on the absolute temperature scale, and reasonable agreement was obtained.

  7. Analytical Modeling of a Loop Heat Pipe with a Flat Evaporator by Applying Thin-Film Theory

    International Nuclear Information System (INIS)

    A steady-state analytical model was presented for a loop heat pipe (LHP) with an evaporator that has a flat geometry. On the basis of a series of reviews of the relevant literature, a sequence of calculations was proposed to predict the temperatures and pressures at each important part of the LHP: the evaporator, liquid reservoir (compensation chamber), liquid line, vapor line, and condenser. The analysis of the evaporator, which is the only part in the LHP that has a capillary structure, was emphasized. Thin-film theory is applied to account for the pressure and temperature in the region adjacent to the liquid-vapor interface in the evaporator. The present study introduced a unique method to estimate the liquid temperature at the interface. Relative freedom was assumed in the configuration of a condenser with a simplified liquid-vapor interface. Our steady-state model was validated by experimental results available in the literature. The relative error was within 3% on the absolute temperature scale, and reasonable agreement was obtained

  8. Indium-tin-oxide thin film deposited by a dual ion beam assisted e-beam evaporation system

    International Nuclear Information System (INIS)

    Indium-tin-oxide (ITO) thin films were deposited on polycarbonate (PC) substrates at low temperatures (<90 deg. C) by a dual ion beam assisted e-beam evaporation system, where one gun (gun 1) is facing ITO flux and the other gun (gun 2) is facing the substrate. In this experiment, effects of rf power and oxygen flow rate of ion gun 2 on the electrical and optical properties of depositing ITO thin films were investigated. At optimal deposition conditions, ITO thin films deposited on the PC substrates larger than 20 cmx20 cm showed the sheet resistance of less than 40 Ω/sq., the optical transmittance of above 90%, and the uniformity of about 5%

  9. Structural, electrical and optical properties of thermochromic VO{sub 2} thin films obtained by reactive electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, J.; Bessaudou, A., E-mail: annie.bessaudou@xlim.fr; Cosset, F.; Crunteanu, A.

    2012-05-01

    We present the structural and physical characterization of vanadium dioxide (VO{sub 2}) thin films prepared by reactive electron beam evaporation from a vanadium target under oxygen atmosphere. We correlate the experimental parameters (substrate temperature, oxygen flow) with the films structural properties under a radiofrequency incident power fixed to 50 W. Most of the obtained layers exhibit monocrystalline structures matching that of the monoclinic VO{sub 2} phase. The temperature dependence of the electrical resistivity and optical transmission for the obtained films show that they present thermoelectric and thermochromic properties, with a phase transition temperature around 68 Degree-Sign C. The results show that for specific experimental conditions the VO{sub 2} layers exhibit sharp changes in electrical and optical properties across the phase transition.

  10. The research and preparation of a bi-layer biodegradable external sheath with directional drug release profiles for vein graft

    Science.gov (United States)

    Liu, Zhenjie; Guo, Zhenying; Si, Yi; Zhang, Xiangman; Shi, Zhenyu; Chen, Feng; Fu, Weiguo

    2013-11-01

    External sheath has been suggested for autologous vein grafts to inhibit neointimal hyperplasia and prevent anastomosis stricture. In this study, we prepared a bi-layer biodegradable paclitaxel-loaded sheaths with a synthetic copolymer poly(ethylene carbonate-ɛ-caprolactone) at room temperature. The bi-layer drug release profiles of the Paclitaxel-loaded (PTX-loaded) sheath significantly slow down the paclitaxel (PTX) release rates and result in a directional drug release way. Moreover, the nanofibrous layer of PTX-loaded poly(EC-CL) sheaths reduced the cytotoxicity and provided a better support for fibroblast adhesion and proliferation than the PTX-loaded layer of the sheaths. Thus, this study demonstrates that the bi-layer PTX-loaded poly(EC-CL) sheath with directional drug release profiles have a promising application for vein graft to against neointimal hyperplasia and anastomotic stricture.

  11. The research and preparation of a bi-layer biodegradable external sheath with directional drug release profiles for vein graft

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhenjie, E-mail: lawson3001@gmail.com [Department of Surgery, Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou (China); Institute of Vascular Surgery, Fudan University, Shanghai (China); Department of Surgery, University of Wisconsin-Madison, WI (United States); Guo, Zhenying [Department of Pathology, Zhejiang Cancer Hospital, Hangzhou (China); Si, Yi [Department of Surgery, University of Wisconsin-Madison, WI (United States); Zhang, Xiangman; Shi, Zhenyu [Institute of Vascular Surgery, Fudan University, Shanghai (China); Chen, Feng [College of Chemical Engineering and Material Science, Zhejiang University of Technology, Hangzhou (China); Fu, Weiguo [Institute of Vascular Surgery, Fudan University, Shanghai (China)

    2013-11-01

    External sheath has been suggested for autologous vein grafts to inhibit neointimal hyperplasia and prevent anastomosis stricture. In this study, we prepared a bi-layer biodegradable paclitaxel-loaded sheaths with a synthetic copolymer poly(ethylene carbonate-ε-caprolactone) at room temperature. The bi-layer drug release profiles of the Paclitaxel-loaded (PTX-loaded) sheath significantly slow down the paclitaxel (PTX) release rates and result in a directional drug release way. Moreover, the nanofibrous layer of PTX-loaded poly(EC-CL) sheaths reduced the cytotoxicity and provided a better support for fibroblast adhesion and proliferation than the PTX-loaded layer of the sheaths. Thus, this study demonstrates that the bi-layer PTX-loaded poly(EC-CL) sheath with directional drug release profiles have a promising application for vein graft to against neointimal hyperplasia and anastomotic stricture.

  12. Effect of deposition temperature on electron-beam evaporated polycrystalline silicon thin-film and crystallized by diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J., E-mail: j.yun@unsw.edu.au; Varalmov, S.; Huang, J.; Green, M. A. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Kim, K. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Suntech R and D Australia, Botany, New South Wales 2019 (Australia)

    2014-06-16

    The effects of the deposition temperature on the microstructure, crystallographic orientation, and electrical properties of a 10-μm thick evaporated Si thin-film deposited on glass and crystallized using a diode laser, are investigated. The crystallization of the Si thin-film is initiated at a deposition temperature between 450 and 550 °C, and the predominant (110) orientation in the normal direction is found. Pole figure maps confirm that all films have a fiber texture and that it becomes stronger with increasing deposition temperature. Diode laser crystallization is performed, resulting in the formation of lateral grains along the laser scan direction. The laser power required to form lateral grains is higher in case of films deposited below 450 °C for all scan speeds. Pole figure maps show 75% occupancies of the (110) orientation in the normal direction when the laser crystallized film is deposited above 550 °C. A higher density of grain boundaries is obtained when the laser crystallized film is deposited below 450 °C, which limits the solar cell performance by n = 2 recombination, and a performance degradation is expected due to severe shunting.

  13. Preparation and characterization of co-evaporated Cu{sub 2}ZnGeSe{sub 4} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Uday Bhaskar, P.; Suresh Babu, G.; Kishore Kumar, Y.B.; Sundara Raja, V., E-mail: sundararajav@rediffmail.com

    2013-05-01

    Cu{sub 2}ZnGeSe{sub 4} (CZGSe), a member of Cu{sub 2}–II–IV–VI{sub 4} family, is a promising material for solar cell absorber layer in thin film heterojunction solar cells like Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSnSe{sub 4} which have been explored in recent years as alternate to CuInGaSe{sub 2} solar cells. The effect of substrate temperature (523 K–723 K) on the growth of CZGSe films is investigated by studying their structural, morphological and optical properties. Raman spectroscopy studies have been done to identify the phases in addition to X-ray diffraction studies. CZGSe films deposited at different substrate temperatures and annealed at 723 K in selenium atmosphere are Cu-rich and Ge-poor and contained secondary phases Cu{sub (2−x)}Se and ZnSe. CZGSe films obtained by reducing the starting Cu mass by 10% were found to be single phase with stannite structure, the lattice parameters being a = 0.563 nm, c = 1.101 nm. The direct optical band gap of CZGSe films is found to be 1.63 eV which is close to ideal band gap of 1.50 eV for the highest photovoltaic conversion efficiency. The films are found to be p-type. - Highlights: • Synthesis of Cu{sub 2}ZnGeSe{sub 4} films for solar cell absorber layer • Effect of substrate temperature on the growth of co-evaporated Cu{sub 2}ZnGeSe{sub 4} films • X-ray diffraction, Raman and morphological studies of Cu{sub 2}ZnGeSe{sub 4} thin films.

  14. Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

    Science.gov (United States)

    Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

    2016-07-01

    Molecular dynamics (MD) simulations have been carried out to investigate evaporation and explosive boiling phenomena of thin film liquid argon on nanostructured solid surface with emphasis on the effect of solid-liquid interfacial wettability. The nanostructured surface considered herein consists of trapezoidal internal recesses of the solid platinum wall. The wetting conditions of the solid surface were assumed such that it covers both the hydrophilic and hydrophobic conditions and hence effect of interfacial wettability on resulting evaporation and boiling phenomena was the main focus of this study. The initial configuration of the simulation domain comprised of a three phase system (solid platinum, liquid argon and vapor argon) on which equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. After equilibrium of the three-phase system was established, the wall was set to different temperatures (130 K and 250 K for the case of evaporation and explosive boiling respectively) to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for hydrophilic and hydrophobic surfaces in cases of both nanostructured surface and flat surface. The results obtained show that both the wetting condition of the surface and the presence of internal recesses have significant effect on normal evaporation and explosive boiling of the thin liquid film. The heat transfer from solid to liquid in cases of surface with recesses are higher compared to flat surface without recesses. Also the surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in

  15. Thickness dependence of structural and optical properties of indium tin oxide nanofiber thin films prepared by electron beam evaporation onto quartz substrates

    Energy Technology Data Exchange (ETDEWEB)

    El-Nahass, M.M. [Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo 11757 (Egypt); El-Menyawy, E.M., E-mail: emad_elmenyawy@yahoo.com [Solid State Electronics Lab, Solid State Physics Department, National Research Center, Dokki, Cairo 12622 (Egypt)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Indium tin oxide thin films grow as nanofibers by e-beam evaporation. Black-Right-Pointing-Pointer The transparency of the films is strongly affected by film thickness. Black-Right-Pointing-Pointer Dielectric constant of the films is independent on film thickness. Black-Right-Pointing-Pointer Optical band gap and carrier concentration decrease with increasing film thickness. - Abstract: Indium tin oxide (ITO) thin films, produced by electron beam evaporation technique onto quartz substrates maintained at room temperature, are grown as nanofibers. The dependence of structural and optical properties of ITO thin films on the film thickness (99-662 nm) has been reported. The crystal structure and morphology of the films are investigated by X-ray diffraction and scanning electron microscope techniques, respectively. The particle size is found to increase with increasing film thickness without changing the preferred orientation along (2 2 2) direction. The optical properties of the films are investigated in terms of the measurements of the transmittance and reflectance determined at the normal incidence of the light in the wavelength range (250-2500 nm). The absorption coefficient and refractive index are calculated and the related optical parameters are evaluated. The optical band gap is found to decrease with the increase of the film thickness, whereas the refractive index is found to increase. The optical dielectric constant and the ratio of the free carrier concentration to its effective mass are estimated for the films.

  16. Thickness dependence of structural and optical properties of indium tin oxide nanofiber thin films prepared by electron beam evaporation onto quartz substrates

    International Nuclear Information System (INIS)

    Highlights: ► Indium tin oxide thin films grow as nanofibers by e-beam evaporation. ► The transparency of the films is strongly affected by film thickness. ► Dielectric constant of the films is independent on film thickness. ► Optical band gap and carrier concentration decrease with increasing film thickness. - Abstract: Indium tin oxide (ITO) thin films, produced by electron beam evaporation technique onto quartz substrates maintained at room temperature, are grown as nanofibers. The dependence of structural and optical properties of ITO thin films on the film thickness (99–662 nm) has been reported. The crystal structure and morphology of the films are investigated by X-ray diffraction and scanning electron microscope techniques, respectively. The particle size is found to increase with increasing film thickness without changing the preferred orientation along (2 2 2) direction. The optical properties of the films are investigated in terms of the measurements of the transmittance and reflectance determined at the normal incidence of the light in the wavelength range (250–2500 nm). The absorption coefficient and refractive index are calculated and the related optical parameters are evaluated. The optical band gap is found to decrease with the increase of the film thickness, whereas the refractive index is found to increase. The optical dielectric constant and the ratio of the free carrier concentration to its effective mass are estimated for the films.

  17. Substrate heating effect on the growth of a CdTe film on an InSb substrate by vacuum evaporation

    Science.gov (United States)

    Jiann-Ruey, Chen; Mau-Phon, Houng; Fenq-Lin, Jenq; Chien-Shyong, Fang; Wan-Sun, Tse

    1991-07-01

    Epitaxial CdTe thin films were grown on the (111) oriented InSb substrate by vacuum evaporation, with the substrate kept at 190-225°C during the film deposition. The chamber pressure during film deposition was at 3.5 × 10-6 mbar. X-ray diffraction was used to determine the film structure, while the full width at half maximum (FWHM) of the X-ray diffraction peak was used to examine the crystallinity of the as-deposited films. The film morphology was observed by the scanning electron microscope (SEM), and the film composition was determined by electron probe microanalysis (EPMA). The film quality was examined by infrared transmission spectroscopy. Results indicate that the quality of the grown CdTe films was improved with the higher substrate temperature during the film deposition.

  18. Structure, surface morphology and electrical properties of evaporated Ni thin films: Effect of substrates, thickness and Cu underlayer

    International Nuclear Information System (INIS)

    Series of Ni thin films have been deposited by thermal evaporation onto glass, Si(111), Cu, mica and Al2O3 substrates with and without a Cu underlayer. The Ni thicknesses, t, are in the 4 to 163 nm range. The Cu underlayer has also been evaporated with a Cu thickness equal to 27, 52 and 90 nm. The effects of substrate, the Ni thickness and the Cu underlayer on the structural and electrical properties of Ni are investigated. Rutherford Backscattering Spectroscopy was used to probe the Ni/Substrate and Ni–Cu underlayer interfaces and to measure both Ni and Cu thicknesses. The texture, the strain and the grain size values were derived from X-ray diffraction experiments. The surface morphology is studied by means of a Scanning Electron Microscope. The electrical resistivity is measured by the four point probe. The Ni films grow with the <111> texture on all substrates. The Ni grain sizes D increase with increasing thickness for the glass, Si and mica substrates and decrease for the Cu one. The strain ε is positive for low thickness, decreases in magnitude and becomes negative as t increases. With the Cu underlayer, the growth mode goes through two phases: first, the stress (grain size) increases (decreases) up to a critical thickness tCr, then stress is relieved and grain size increases. All these results will be discussed and correlated. - Highlights: • The structural and electrical properties of evaporated Ni thin films are studied. • The effect of thickness, substrates and Cu underlayer is investigated. • Texture, grain size, strain and surface morphology are discussed. • Growth modes are described as a function of Ni thickness

  19. Structural, morphological, and optoelectrical characterization of Bi2S3 thin films grown by co-evaporation

    Science.gov (United States)

    Mesa, F.; Arredondo, C. A.; Vallejo, W.

    2016-03-01

    This work presents the results of synthesis and characterization of polycrystalline n-type Bi2S3 thin films. The films were grown through a chemical reaction from co-evaporation of their precursor elements in a soda-lime glass substrate. The effect of the experimental conditions on the optical, morphological structural properties, the growth rate, and the electrical conductivity (σ) was studied through spectral transmittance, X-ray diffraction (XRD), atomic force microscopy (AFM) and σ versus T measurements, respectively. The results showed that the films grow only in the orthorhombic Bi2S3 bismuthinite phase. It was also found that the Bi2S3 films present an energy band gap (Eg) of about 1.38 eV. In addition to these results, the electrical conductivity of the Bi2S3 films was affected by both the transport of free carriers in extended states of the conduction band and for variable range hopping transport mechanisms, each one predominating in a different temperature range.

  20. 薄膜蒸发器的分离效率%Separation Efficiency of Thin-film Evaporators

    Institute of Scientific and Technical Information of China (English)

    R. Billet

    2004-01-01

    The recovery of contaminants and useful substances from liquid wastes, the purification of production effluents and the separation of thermally instable mixtures are some of the multivarious applications of thin-film distillors in many processes of the chemical and allied industries and of the food industries. In a study carried out in pilot plants with distillation test systems there was found a good agreement between the experimental separation results and those obtained by computing with a theorectical model; the latter is based on the assumption of phase equilibrium between the vapour formed on an infinitely small element of area in a liquid film of any given concentric periphery of the vertically arranged evaporator. These tests were perfomed under various phase loads.

  1. Preparation and Properties of Evaporated CdTe and All Thin Film CdTe/CdS Solar Cells

    Science.gov (United States)

    Shahzad, Naseem

    1991-05-01

    Cadmium telluride thin films were prepared by vacuum evaporation of CdTe powder in an attempt to fabricate all thin film solar cells of the type CdTe/CdS. Characterization of CdTe has shown it to have a band gap of 1.522 eV and a resistivity of 22Ω-cm. As prepared, solar cells exhibited low values of output parameters. Given quantity of copper was then deposited on top of the CdTe/CdS solar cells and the whole system was annealed at 350° C. This copper doping changed the output parameters favorably with a maximum efficiency of 1.9%.

  2. Effect of the spin-twist structure on the spin-wave dynamics in Fe55Pt45/Ni80Fe20 exchange coupled bi-layers with varying Ni80Fe20 thickness

    International Nuclear Information System (INIS)

    We have investigated optically induced ultrafast magnetization dynamics of a series of Fe55Pt45/Ni80Fe20 exchange spring bi-layers with varying Ni80Fe20 thickness. Rich spin-wave spectra are observed; whose frequency shows a strong dependence on the Ni80Fe20 layer thickness. Micromagnetic simulations based on a simplified magnetic microstructure were able to reproduce the experimental data qualitatively. The spin twist structure introduced in the Ni80Fe20 layer gives rise to new modes in the composite system as opposed to the bare Ni80Fe20 films

  3. Effect of the spin-twist structure on the spin-wave dynamics in Fe55Pt45/Ni80Fe20 exchange coupled bi-layers with varying Ni80Fe20 thickness

    Science.gov (United States)

    Pal, Semanti; Barman, Saswati; Hellwig, Olav; Barman, Anjan

    2014-05-01

    We have investigated optically induced ultrafast magnetization dynamics of a series of Fe55Pt45/Ni80Fe20 exchange spring bi-layers with varying Ni80Fe20 thickness. Rich spin-wave spectra are observed; whose frequency shows a strong dependence on the Ni80Fe20 layer thickness. Micromagnetic simulations based on a simplified magnetic microstructure were able to reproduce the experimental data qualitatively. The spin twist structure introduced in the Ni80Fe20 layer gives rise to new modes in the composite system as opposed to the bare Ni80Fe20 films.

  4. Effects of co-sintering in self-standing CGO/YSZ and CGO/ ScYSZ dense bi-layers

    DEFF Research Database (Denmark)

    Teocoli, Francesca; Ni, De Wei; Brodersen, Karen; Foghmoes, Søren Preben Vagn; Ramousse, Severine; Esposito, Vincenzo

    2014-01-01

    -standing bi-layered electrolyte system. The combined use of thermo-mechanical analysis, optical dilatometry, and scanning electron microscopy ensures a systematic characterization of both the individual layers and CGO/YSZ and CGO/ScYSZ bi-layered laminates. The results of the co-firing process of the bi...

  5. Effect of Substrate Temperature on Structural and Optical Properties of Nanocrystalline CdTe Thin Films Deposited by Electron Beam Evaporation

    Directory of Open Access Journals (Sweden)

    M. Rigana Begam

    2013-07-01

    Full Text Available Nanocrystalline Cadmium Telluride (CdTe thin films were deposited onto glass substrates using electron beam evaporation technique. The effect of substrate temperature on the structural, morphological and optical properties of CdTe thin films has been investigated. All the CdTe films exhibited zinc blende structure with (111 preferential orientation. The crystallite size of the films increased from 35 nm to 116 nm with the increase of substrate temperature and the band gap of the films decreased from 2.87 eV to 2.05 eV with the increase of the crystallite size.

  6. SnS absorber thin films by co-evaporation: Optimization of the growth rate and influence of the annealing

    International Nuclear Information System (INIS)

    Tin sulfide thin films were prepared by co-evaporation on soda-lime glass substrates, for use as absorber layers. The synthesis was carried out at 350 °C substrate temperature and varying the growth rate in the 2-6 Å/s range, adjusting the deposition time in order to obtain thicknesses in the 700-1500 nm range. After evaporation, the samples were heated at 400 °C and 500 °C under various atmospheres. The evolution of the morphological, structural and optical properties has been analyzed as a function of the thickness and deposition rate, before and after annealing. For the samples grown at the lowest rate, SnS and Sn2S3 phase mixing has been observed by X-ray diffraction. Samples with reduced thickness preferably crystallize in the SnS phase, whereas thicker layers become richer in the Sn2S3 phase. The sulfur treatment of samples prepared at the lowest rate results in the formation of SnS2 phase. Otherwise, the samples obtained at the highest rates show single-phase SnS after heating at 400 °C in sulfur atmosphere, with gap energy values around 1.24 eV. - Highlights: • Tin sulfide thin films were deposited by co-evaporation at different growth rates. • The influence of the growth rate and post-annealing at different conditions was studied. • The SnS phase was obtained by optimizing the growth rate and the annealing process. • The SnS phase presented properties for use as absorber layer

  7. SnS absorber thin films by co-evaporation: Optimization of the growth rate and influence of the annealing

    Energy Technology Data Exchange (ETDEWEB)

    Robles, Víctor, E-mail: victor.robles@ciemat.es; Trigo, Juan Francisco; Guillén, Cecilia; Herrero, José

    2015-05-01

    Tin sulfide thin films were prepared by co-evaporation on soda-lime glass substrates, for use as absorber layers. The synthesis was carried out at 350 °C substrate temperature and varying the growth rate in the 2-6 Å/s range, adjusting the deposition time in order to obtain thicknesses in the 700-1500 nm range. After evaporation, the samples were heated at 400 °C and 500 °C under various atmospheres. The evolution of the morphological, structural and optical properties has been analyzed as a function of the thickness and deposition rate, before and after annealing. For the samples grown at the lowest rate, SnS and Sn{sub 2}S{sub 3} phase mixing has been observed by X-ray diffraction. Samples with reduced thickness preferably crystallize in the SnS phase, whereas thicker layers become richer in the Sn{sub 2}S{sub 3} phase. The sulfur treatment of samples prepared at the lowest rate results in the formation of SnS{sub 2} phase. Otherwise, the samples obtained at the highest rates show single-phase SnS after heating at 400 °C in sulfur atmosphere, with gap energy values around 1.24 eV. - Highlights: • Tin sulfide thin films were deposited by co-evaporation at different growth rates. • The influence of the growth rate and post-annealing at different conditions was studied. • The SnS phase was obtained by optimizing the growth rate and the annealing process. • The SnS phase presented properties for use as absorber layer.

  8. Effect of Deposition Rate on Structure and Surface Morphology of Thin Evaporated Al Films on Dielectrics and Semiconductors

    DEFF Research Database (Denmark)

    Bordo, K.; Rubahn, H. G.

    2012-01-01

    structure and surface morphology of the as-deposited Al films were studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM imaging of the films showed that the mean grain size of thin Al films on all of the substrates increased from 20 nm - 30 nm to 50 nm - 70 nm with......Aluminum (Al) films with thickness of 100 nm were grown on unheated glass, silicon and mica substrates by electron beam evaporation. The deposition rates were adjusted in the range between 0.1 nm/s and 2 nm/s, the pressure in the vacuum chamber during deposition was lower than 1.10(-3) Pa. The...... increase of the deposition rate. Quantitative AFM characterization showed that for all substrates the root mean square surface roughness increases monotonically with increasing the deposition rate from 0.1 nm/s to 2 nm/s. The observed effects of the deposition rate on the grain size and surface roughness...

  9. Field evaporation behavior in [0 0 1] FePt thin films

    International Nuclear Information System (INIS)

    Though the atom probe has provided unprecedented atomic identification and spatial imaging capability, the basic reconstruction assumption of a smooth hemispherical tip shape creates significant challenges in yielding high fidelity chemical information for atomic species with extreme differences in fields required for field evaporation. In the present study, the evaporation behavior and accompanying artifacts are examined for the super-cell lattice structure of L10 FePt, where alternating Fe and Pt planes exist in the [0 0 1] orientation. Elemental Fe and Pt have significant differences in field strengths providing a candidate system to quantify these issues. Though alloys can result in changes in the elemental field strength, the intrinsic nature of elemental planes in [0 0 1] L10 provides a system to determine to what extent basic assumptions of elemental field strengths can break down in understanding reconstruction artifacts in this intermetallic alloy. The reconstruction of field evaporation experiments has shown depletion of Fe at the (0 0 2) pole and zone axes. Compositional profiles revealed an increase in Fe and atom count moving outward from the pole. The depletion at the low indexed pole and zone axes was determined to be the result of local magnification and electrostatic effects. The experimental results are compared to an electrostatic simulation model. -- Research highlights: → Field evaporation behavior of the ordered L10 FePt was investigated using APT. → It was found that close to the (0 0 2) pole the number density of Fe ions detected was significantly lowered because of ion trajectory aberration effects. → Simulations incorporating a face center cubic structure have qualitatively reproduced the experimental findings without the inclusion of a binding term or thermal effects. → Both experimental and simulation results have shown that the difference in evaporation field between the two components of the alloy contributed to the trajectory

  10. Characterization of lysozyme films produced by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Purice, Andreea; Schou, Jørgen; Kingshott, Peter;

    2007-01-01

    growing film. Scanning electron microscopy (SEM) images demonstrate that the silicon substrate is completely covered by lysozyme films thicker than 100 nm. Deposition was also made from a target with pressed (100%) solid lysozyme, but the deposition was difficult to handle and with a much slower rate than...

  11. Pulsed laser treatment of gold and black gold thin films fabricated by thermal evaporation

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Fitl, P.; Krasilnikova Sytchkova, A.; Bulíř, Jiří; Lančok, Ján; Pokorný, Petr; Najdek, D.; Bočan, Jiří

    2009-01-01

    Roč. 7, č. 2 (2009), s. 327-331. ISSN 1895-1082. [International Conference on Solid State Surfaces and Interfaces. Smolenice Castle, 24.11.2008-27.11.2008] R&D Projects: GA AV ČR IAA100100718; GA AV ČR IAA100100729 Institutional research plan: CEZ:AV0Z10100522 Keywords : metal blacks * gold * thermal evaporation * laser treatment * nanostructure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.728, year: 2009

  12. Optical and structural study of In2S3 thin films growth by co-evaporation and chemical bath deposition (CBD) on Cu3BiS3

    International Nuclear Information System (INIS)

    Highlights: • In2S3 thin films usually grow like an ultrathin. • Samples grown by CBD have a higher degree of coverage of the substrate unlike co-evaporation method. • Solar cells of Al/TCO/In2S3/Cu3BiS3/Mo structure. • In2S3 thin films were deposited on Cu3BiS3 (CBS), with of In2S3 β-phase with tetragonal structure. - Abstract: We present the growth of In2S3 onto Cu3BiS3 layers and soda-lime glass (SLG) substrates by using chemical bath deposition (CBD) and physical co-evaporation. The results reveal that the microstructure and the optical properties of the In2S3 films are highly dependent on the growth method. X-ray diffractrograms show that In2S3 films have a higher crystallinity when growing by co-evaporation than by CBD. In2S3 thin films grown by CBD with a thickness below 170 nm have an amorphous structure however when increasing the thickness the films exhibit two diffraction peaks associated to the (1 0 3) and (1 0 7) planes of the β-In2S3 tetragonal structure. It was also found that the In2S3 films present an energy bandgap (Eg) of about 2.75 eV, regardless of the thickness of the samples

  13. Obtaining phase-pure CZTS thin films by annealing vacuum evaporated CuS/SnS/ZnS stack

    Science.gov (United States)

    Sánchez, T. G.; Mathew, X.; Mathews, N. R.

    2016-07-01

    Cu2ZnSnS4 (CZTS) thin films were obtained by the sequential thermal evaporation of metal binary sulfides in the order CuS/SnS/ZnS, followed by annealing in Ar/S atmosphere. The as-grown films were annealed at different temperatures ranging between 350 and 600 °C, for 10 min. Based on the preliminary results, the temperatures 550 °C and 600 °C were selected for further optimization and a second batch of films were annealed for different time durations (10 min, 30 min and 60 min) at these temperatures in order to identify the conditions to obtain phase-pure CZTS films. The structural properties and chemical compositions at each temperature were investigated in order to optimize the phase purity and film stoichiometry. We have identified adequate and reproducible conditions to obtain the elemental ratio Cu/(Zn+Sn) and Zn/Sn close to 0.78 and 1.19 respectively, which is in the range of material composition required for promising solar cells. In addition the optimized material showed excellent optical and electrical properties to be used as a photovoltaic absorber layer. The optical band gap was found to be about 1.52 eV, and the carrier concentration, hall mobility, and resistivity were in the range of 8.372×1015 cm-3, 3.103 cm2/Vs and 340.3 Ω-cm respectively. Three traps with activation energies 4.39, 8.1, and 34 meV were detected.

  14. Morphological manipulation of the nonlinear optical response of ZnO thin films grown by thermal evaporation

    International Nuclear Information System (INIS)

    ZnO thin films with different micro-/nano-structured morphologies have been fabricated using thermal evaporation technique. The micro-/nano-structures ranged from dense grains to nanorods and nanowires. The fabricated films were characterized using x-ray diffraction and field emission scanning electron microscopy (FE-SEM) techniques for determining their crystalline behavior and evaluating their morphology, respectively. Photoluminescence (PL) studies revealed two emission peaks in these films, one in the UV region due to exciton emission and the other in the visible spectral region due to Zn or Oxygen vacancies/defects. The effect of these different micro-/nano-structures on the third-order nonlinear optical (NLO) response has been scrutinized using the Z-scan technique with femtosecond (fs), MHz and picosecond (ps), kHz pulses at a wavelength of 800 nm. Various NLO coefficients such as two-photon absorption (β), nonlinear refractive index (n2), Re [χ (3)], Im [χ (3)] and χ (3) were evaluated. The obtained χ(3) values were ∼10−7 e.s.u. in the fs regime and ∼10−10 e.s.u. in the ps regime. Optical limiting studies of these films were also performed and limiting thresholds were estimated to be 15–130 μJ cm−2 in the fs regime while in ps regime the corresponding values were 1–3 J cm−2. The NLO data clearly designates strong third-order nonlinearities in these ZnO thin films with possible applications in photonics. (paper)

  15. Electrostatic quadrupole plasma mass spectrometer measurements during thin film depositions using simultaneous matrix assisted pulsed laser evaporation and magnetron sputtering

    International Nuclear Information System (INIS)

    A hybrid plasma deposition process, combining matrix assisted pulsed laser evaporation (MAPLE) of carbon nanopearls (CNPs) with magnetron sputtering of gold was investigated for growth of composite films, where 100 nm sized CNPs were encapsulated into a gold matrix. Composition and morphology of such composite films was characterized with x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM) analysis. Carbon deposits on a gold magnetron sputter target and carbon impurities in the gold matrices of deposited films were observed while codepositing from gold and frozen toluene-CNP MAPLE targets in pure argon. Electrostatic quadrupole plasma analysis was used to determine that a likely mechanism for generation of carbon impurities was a reaction between toluene vapor generated from the MAPLE target and the argon plasma originating from the magnetron sputtering process. Carbon impurities of codeposited films were significantly reduced by introducing argon-oxygen mixtures into the deposition chamber; reactive oxygen species such as O and O+ effectively removed carbon contamination of gold matrix during the codeposition processes. Increasing the oxygen to argon ratio decreased the magnetron target sputter rate, and hence hybrid process optimization to prevent gold matrix contamination and maintain a high sputter yield is needed. High resolution TEM with energy dispersive spectrometry elemental mapping was used to study carbon distribution throughout the gold matrix as well as embedded CNP clusters. This research has demonstrated that a hybrid MAPLE and magnetron sputtering codeposition process is a viable means for synthesis of composite thin films from premanufactured nanoscale constituents, and that cross-process contaminations can be overcome with understanding of hybrid plasma process interaction mechanisms.

  16. Polycrystalline lead iodide films produced by solution evaporation and tested in the mammography X-ray energy range

    Science.gov (United States)

    Condeles, J. F.; Mulato, M.

    2016-02-01

    Lead iodide polycrystalline films have been deposited on corning glass substrates using solution evaporation in oven. Films 6 μm-thick were obtained with full coverage of the substrates as verified by scanning electron microscopy. Some pin-holes were observable. X-ray diffraction revealed a crystalline structure corresponding to the 4 H-PbI2 polytype formation. Polarized Raman scattering experiments indicated a lamellar structure. Anisotropy was also investigated using depolarization ratio calculations. The optical and electrical properties of the samples were investigated using photoluminescence and dark conductivity as a function of temperature, respectively. Activation energies of 0.10 up to 0.89 eV were related to two main electrical transport mechanisms. Films were also exposed to X-ray irradiation in the mammography X-ray energy range. The detector produced was also exposed to X-ray from 5 mR up to 1450 mR. A linear response was observed as a function of dose with a slope of 0.52 nA/mm2 per mR.

  17. Annealing Effect on the Thermoelectric Properties of Bi2Te3 Thin Films Prepared by Thermal Evaporation Method

    Directory of Open Access Journals (Sweden)

    Jyun-Min Lin

    2013-01-01

    Full Text Available Bismuth telluride-based compounds are known to be the best thermoelectric materials within room temperature region, which exhibit potential applications in cooler or power generation. In this paper, thermal evaporation processes were adopted to fabricate the n-type Bi2Te3 thin films on SiO2/Si substrates. The influence of thermal annealing on the microstructures and thermoelectric properties of Bi2Te3 thin films was investigated in temperature range 100–250°C. The crystalline structures and morphologies were characterized by X-ray diffraction and field emission scanning electron microscope analyses. The Seebeck coefficients, electrical conductivity, and power factor were measured at room temperature. The experimental results showed that both the Seebeck coefficient and power factor were enhanced as the annealing temperature increased. When the annealing temperature increased to 250°C for 30 min, the Seebeck coefficient and power factor of n-type Bi2Te3-based thin films were found to be about −132.02 μV/K and 6.05 μW/cm·K2, respectively.

  18. Optical properties on thermally evaporated and heat-treated disodium phthalocyanine derivative thin films

    Indian Academy of Sciences (India)

    M E Sánchez-Vergara; M Rivera; R A Torres-García; C O Perez-Baeza; E A Loza-Neri

    2014-08-01

    Thin films were grown on quartz substrates and crystalline silicon wafers using disodium phthalocyanine and the organic ligands 2,6-diaminoanthraquinone, 2,6-dihydroxianthraquinone and its potassium derivative salt. The surface morphology of these films was analysed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). IR spectroscopy was employed in order to investigate possible changes of the intra-molecular bonds between the powder compounds and thin films. The optical parameters have been investigated using spectrophotometric measurements of absorbance in the wavelength range of 200–1100 nm and the effects of post-deposition heat treatment were analysed. The absorption spectra recorded in the UV–Vis region for the deposited samples showed two bands, namely the Q and Soret bands. The absorption coefficient in the absorption region reveals non-direct transitions. In addition, the optical gap dependence upon the thickness of these thin films was evaluated.

  19. Tailoring the multiple electrically resonant transparency through bi-layered metamaterial-induced coupling oscillators

    Science.gov (United States)

    Zhao, Jiaxin; Han, Song; Lin, Hai; Yang, Helin

    2015-11-01

    Metamaterials (MMs) can be tailored to support electromagnetic interference, which is the kernel for the material-based electromagnetically induced transparency (EIT) phenomena, alternatively transparency based on electric interference can be deemed as electrically resonant transparency (ERT). Here, we experimentally and theoretically demonstrate two kinds of bi-layered MMs. The C3-C6 hybrid MM exhibits triple-mode ERT with transmission peaks of 0.84 at 9.6 GHz, 0.92 at 10.4 GHz, and 0.93 at 11.5 GHz for the horizontally polarized wave, and dual-mode ERT with transmission peaks of 0.84 at 8.8 GHz and 0.91 at 10.2 GHz for the vertically polarized wave. However, the C4-C8 hybrid MM, with two stable transparent peaks of 0.92 and 0.88 at 10.46 GHz and 11.61 GHz, is proven to be polarization independent. The measured results show excellent agreement with numerical simulations. A coupled oscillator model is employed to theoretically study the near field interference between the induced dipoles on the transmission properties. The results presented here will find their application value for multi-mode slow light devices, filters and attenuators, and so on.

  20. Strain-modulated excitonic gaps in mono- and bi-layer MoSe2

    Science.gov (United States)

    Jianting, Ji; Anmin, Zhang; Tianlong, Xia; Po, Gao; Yinghao, Jie; Qian, Zhang; Qingming, Zhang

    2016-07-01

    Photoluminescence (PL) and Raman spectra under uniaxial strain were measured in mono- and bi-layer MoSe2 to comparatively investigate the evolution of excitonic gaps and Raman phonons with strain. We observed that the strain dependence of excitonic gaps shows a nearly linear behavior in both flakes. One percent of strain increase gives a reduction of ∼ 42 meV (∼ 35 meV) in A-exciton gap in monolayer (bilayer) MoSe2. The PL width remains little changed in monolayer MoSe2 while it increases rapidly with strain in the bilayer case. We have made detailed discussions on the observed strain-modulated results and compared the difference between monolayer and bilayer cases. The hybridization between 4d orbits of Mo and 4p orbits of Se, which is controlled by the Se–Mo–Se bond angle under strain, can be employed to consistently explain the observations. The study may shed light into exciton physics in few-layer MoSe2 and provides a basis for their applications. Project supported by the National Basic Research Program of China (Grant No. 2012CB921701) and the National Natural Science Foundation of China (Grant Nos. 11474357 and 11004245). Qingming Zhang and Tianlong Xia were supported by the Fundamental Research Funds for the Central Universities of China and the Research Funds of Renmin University of China.

  1. A study on DPL model of heat transfer in bi-layer tissues during MFH treatment.

    Science.gov (United States)

    Kumar, Dinesh; Kumar, P; Rai, K N

    2016-08-01

    In this paper, dual-phase-lag bioheat transfer model subjected to Fourier and non-Fourier boundary conditions for bi-layer tissues has been solved using finite element Legendre wavelet Galerkin method (FELWGM) during magnetic fluid hyperthermia. FELWGM localizes small scale variation of solution and fast switching of functional bases. It has been observed that moderate hyperthermia temperature range (41-46°C) can be better achieved in spherical symmetric coordinate system and treatment method will be independent of the Fourier and non-Fourier boundary conditions used. The effect of phase-lag times has been observed only in tumor region. FCC FePt magnetic nano-particle produces more effective treatment with respect to other magnetic nano-particles. The effect of variability of magnetic heat source parameters (magnetic induction, frequency, diameter of magnetic nano-particles, volume fractional of magnetic nano-particles and ligand layer thickness) has been investigated. The physical property of these parameters has been described in detail during magnetic fluid hyperthermia (MFH) treatment and also discussed the clinical application of MFH in Oncology. PMID:27289539

  2. Nonlinear dynamics of bi-layered graphene sheet, double-walled carbon nanotube and nanotube bundle

    Science.gov (United States)

    Gajbhiye, Sachin O.; Singh, S. P.

    2016-05-01

    Due to strong van der Waals (vdW) interactions, the graphene sheets and nanotubes stick to each other and form clusters of these corresponding nanostructures, viz. bi-layered graphene sheet (BLGS), double-walled carbon nanotube (DWCNT) and nanotube bundle (NB) or ropes. This research work is concerned with the study of nonlinear dynamics of BLGS, DWCNT and NB due to nonlinear interlayer vdW forces using multiscale atomistic finite element method. The energy between two adjacent carbon atoms is represented by the multibody interatomic Tersoff-Brenner potential, whereas the nonlinear interlayer vdW forces are represented by Lennard-Jones 6-12 potential function. The equivalent nonlinear material model of carbon-carbon bond is used to model it based on its force-deflection relation. Newmark's algorithm is used to solve the nonlinear matrix equation governing the motion of the BLGS, DWCNT and NB. An impulse and harmonic excitations are used to excite these nanostructures under cantilevered, bridged and clamped boundary conditions. The frequency responses of these nanostructures are computed, and the dominant resonant frequencies are identified. Along with the forced vibration of these structures, the eigenvalue extraction problem of armchair and zigzag NB is also considered. The natural frequencies and corresponding mode shapes are extracted for the different length and boundary conditions of the nanotube bundle.

  3. Pilot-Scale Test Results Of A Thin Film Evaporator System For Management Of Liquid High-Level Wastes At The Hanford Site Washington USA -11364

    International Nuclear Information System (INIS)

    A modular, transportable evaporator system, using thin film evaporative technology, is planned for deployment at the Hanford radioactive waste storage tank complex. This technology, herein referred to as a wiped film evaporator (WFE), will be located at grade level above an underground storage tank to receive pumped liquids, concentrate the liquid stream from 1.1 specific gravity to approximately 1.4 and then return the concentrated solution back into the tank. Water is removed by evaporation at an internal heated drum surface exposed to high vacuum. The condensed water stream will be shipped to the site effluent treatment facility for final disposal. This operation provides significant risk mitigation to failure of the aging 242-A Evaporator facility; the only operating evaporative system at Hanford maximizing waste storage. This technology is being implemented through a development and deployment project by the tank farm operating contractor, Washington River Protection Solutions (WRPS), for the Office of River Protection/Department of Energy (ORPIDOE), through Columbia Energy and Environmental Services, Inc. (Columbia Energy). The project will finalize technology maturity and install a system at one of the double-shell tank farms. This paper summarizes results of a pilot-scale test program conducted during calendar year 2010 as part of the ongoing technology maturation development scope for the WFE.

  4. Optimization of Bi2Te3 and Sb2Te3 thin films deposited by co-evaporation on polyimide for thermoelectric applications

    OpenAIRE

    L.M. Gonçalves; Alpuim, P.; Rowe, D. M.; Correia, J H; Couto, Carlos; Gao Min

    2005-01-01

    The optimization of the deposition process for n-type Bi2Te3 and p-type Sb2Te3 semiconductor thin films for thermoelectric applications is reported. The films were deposited on a 25 μm thick flexible polyimide (Kapton) substrate by co-evaporation of Bi and Te, for the n-type element, and Sb and Te, for the p-type element.

  5. Conductive and transparent multilayer films for low-temperature TiO2/Ag/SiO2 electrodes by E-beam evaporation with IAD

    OpenAIRE

    Chiu, Po-Kai; Lee, Chao-Te; Chiang, Donyau; Cho, Wen-Hao; Hsiao, Chien-Nan; Chen, Yi-Yan; Huang, Bo-Ming; Yang, Jer-Ren

    2014-01-01

    Conductive and transparent multilayer thin films consisting of three alternating layers (TiO2/Ag/SiO2, TAS) have been fabricated for applications as transparent conducting oxides. Metal oxide and metal layers were prepared by electron-beam evaporation with ion-assisted deposition, and the optical and electrical properties of the resulting films as well as their energy bounding characteristics and microstructures were carefully investigated. The optical properties of the obtained TAS material ...

  6. Corrosion performance of bi-layer Ni/Cr2C3-NiCr HVAF thermal spray coating

    Science.gov (United States)

    Sadeghimeresht, E.; Markocsan, N.; Nylén, P.; Björklund, S.

    2016-04-01

    The corrosion behavior of three HVAF thermal spray coating systems (A: single-layer Ni, B: single-layer Cr2C3-NiCr coatings, and C: bi-layer Ni/Cr2C3-NiCr coating) was comparatively studied using immersion, salt spray, and electrochemical tests. Polarization and EIS results showed that the corrosion behavior of Cr2C3-NiCr coatings in 3.5 wt.% NaCl solution was significantly improved by adding the intermediate layer of Ni. It was illustrated that the polarization resistance of the bi-layer Ni/Cr2C3-NiCr and single-layer Cr2C3-NiCr coatings were around 194 and 38 kΩ cm2, respectively. Microstructure analysis revealed that the bond coating successfully prevented the corrosion propagation toward the coating.

  7. Microstructures and properties of Cr-Cu/W-Cu bi-layer composite coatings prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiaping; Feng, Xiaomei; Shen, Yifu; Chen, Cheng; Duan, Cuiyuan [Nanjing Univ. of Aeronautics and Astronautics (China). Dept. of Materials Science and Technology

    2016-06-15

    Cr-Cu/W-Cu bi-layer coatings with composite structures were fabricated by means of mechanical alloying. The Cr-Cu layer and the W-Cu layer were deposited successively and the as-synthesized bi-layer coating was made up of an inner Cr-Cu layer and an outer W-Cu layer. Microstructures, chemical and phase compositions of the as-prepared coatings were characterized. The results indicated that the bonding between the inner coating and the substrate was improved with the increase of Cu in the raw powder. The annealing treatment of the inner Cr-Cu layer was beneficial to the bonding between the inner Cr-Cu coating and the outer W-Cu coating layer. Mechanical properties such as microhardness, friction and wear resistance were tested. The as-synthesized coating could effectively improve the hardness and wear resistance of the Cu substrate.

  8. Alginate/chitosan based bi-layer composite membrane as potential sustained-release wound dressing containing ciprofloxacin hydrochloride

    Science.gov (United States)

    Han, Fei; Dong, Yang; Song, Aihua; Yin, Ran; Li, Sanming

    2014-08-01

    The aims of this research were to develop and evaluate a novel ciprofloxacin hydrochloride loaded bi-layer composite membrane based on alginate and chitosan. In vitro antimicrobial activity, drug permeation study, morphology, cytotoxicity, primary skin irritation and in vivo pharmacodynamics were investigated. Results showed that the membranes could inhibit the growth of microorganisms for longer than 7 days. And there was no significant decrease in the metabolic activity of the Hacat fibroblasts cells were treated with the membranes. No edema and erythema were observed after administration of membranes on the rabbit skin after 14 days. Moreover, the results of pharmacodynamics showed that the membranes were more effective in improving the wound healing process. In conclusion, a novel bi-layer composite membrane was developed and results suggested that it could be exploited as sustained-release wound dressings.

  9. Structure of MoCN films deposited by cathodic arc evaporation

    International Nuclear Information System (INIS)

    Molybdenum carbonitride (MoCN) coatings were deposited onto HS6-5-2 steel substrate using pure Mo targets in mixed acetylene and nitrogen atmosphere by cathodic arc evaporation. The structural properties of MoCN coatings with different carbon contents (as an effect of the C2H2 flow rate) were investigated systematically. Phase and chemical composition evolution of the coatings were characterized both by the glancing angle of X-ray diffraction (XRD) and wavelength dispersive spectrometry, respectively. These analyses have been supplemented by estimates of grain sizes and stress in the coatings. The XRD results show that the increase in acetylene flow rate causes the formation of molybdenum carbide (MoC) hexagonal phase in the coatings, a reduction of grain size and an increase in internal stress. - Highlights: • MoN and MoCN coatings were deposited by cathodic arc evaporation in nitrogen atmosphere. • MoCN coatings were formed using different acetylene flow rates. • Phase composition evolution was observed. • Crystallite size and stress were calculated

  10. Structure of MoCN films deposited by cathodic arc evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Gilewicz, A., E-mail: adam.gilewicz@tu.koszalin.pl [Koszalin University of Technology, Faculty of Technology and Education, Sniadeckich 2, 75-453 Koszalin (Poland); Jedrzejewski, R.; Kochmanska, A.E. [West Pomeranian University of Technology Szczecin, Faculty of Mechanical Engineering and Mechatronics, 19 Piastów Ave., 70-313 Szczecin (Poland); Warcholinski, B. [Koszalin University of Technology, Faculty of Technology and Education, Sniadeckich 2, 75-453 Koszalin (Poland)

    2015-02-27

    Molybdenum carbonitride (MoCN) coatings were deposited onto HS6-5-2 steel substrate using pure Mo targets in mixed acetylene and nitrogen atmosphere by cathodic arc evaporation. The structural properties of MoCN coatings with different carbon contents (as an effect of the C{sub 2}H{sub 2} flow rate) were investigated systematically. Phase and chemical composition evolution of the coatings were characterized both by the glancing angle of X-ray diffraction (XRD) and wavelength dispersive spectrometry, respectively. These analyses have been supplemented by estimates of grain sizes and stress in the coatings. The XRD results show that the increase in acetylene flow rate causes the formation of molybdenum carbide (MoC) hexagonal phase in the coatings, a reduction of grain size and an increase in internal stress. - Highlights: • MoN and MoCN coatings were deposited by cathodic arc evaporation in nitrogen atmosphere. • MoCN coatings were formed using different acetylene flow rates. • Phase composition evolution was observed. • Crystallite size and stress were calculated.

  11. Effect of substrate temperatures on evaporated In2S3 thin film buffer layers for Cu(In,Ga)Se2 solar cells

    International Nuclear Information System (INIS)

    For the realization of vacuum in-line process in the fabrication of Cu(In,Ga)Se2 (CIGS) solar cells, In2S3 thin film buffer layers for CIGS have been deposited on glasses and CIGS layers with a thickness of about 650 Å by thermal evaporation process. During the thermal evaporation, the temperature of the substrate was varied from room temperature to 500 °C by heating and the grown In2S3 films were investigated and analyzed in terms of the optimized buffer layer for CIGS solar cells. From the results of scanning electron microscope and X-ray diffraction, the In2S3 thin film deposited at a higher substrate temperature showed the larger grain size and the films have amorphous structural characteristics. Although the structural characteristics such as the atomic ratio of In to S and transmittance of the In2S3 thin films were not proportional to temperature, it was possible to obtain the large optical band gap of In2S3 films of about 3.8–3.9 eV enough to be used as the buffer layer of CIGS. - Highlights: • In2S3 films were deposited at various substrate temperatures by thermal evaporation. • The atomic ratio of In to S in the In2S3 film has the highest value at 300 °C. • The In2S3 film has a band gap of about 3.8 eV because of its amorphous structure. • The In2S3 film is expected to be used as a buffer layer by in-line vacuum process

  12. Complex boron redistribution kinetics in strongly doped polycrystalline-silicon/nitrogen-doped-silicon thin bi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Abadli, S. [Department of Electrical Engineering, University Aout 1955, Skikda, 21000 (Algeria); LEMEAMED, Department of Electronics, University Mentouri, Constantine, 25000 (Algeria); Mansour, F. [LEMEAMED, Department of Electronics, University Mentouri, Constantine, 25000 (Algeria); Pereira, E. Bedel [CNRS-LAAS, 7 avenue du colonel Roche, 31077 Toulouse (France)

    2012-10-15

    We have investigated the complex behaviour of boron (B) redistribution process via silicon thin bi-layers interface. It concerns the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method at 480 C, by using in-situ nitrogen-doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P{sup +}) layer. To avoid long-range B redistributions, thermal annealing was carried out at relatively low-temperatures (600 C and 700 C) for various times ranging between 30 min and 2 h. To investigate the experimental secondary ion mass spectroscopy (SIMS) doping profiles, a redistribution model well adapted to the particular structure of two thin layers and to the effects of strong-concentrations has been established. The good adjustment of the simulated profiles with the experimental SIMS profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders. The increasing kinetics of the B peak concentration near the bi-layers interface is well reproduced by the established model. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Water ice as a matrix for film production by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Schou, Jørgen; Christensen, Bo Toftmann; Pedrys, R.

    2007-01-01

    We have studied water ice as a matrix for the production of PEG (polyethylene glycol) films by MAPLE at 355 nm. The deposition rate is small compared with other matrices typically used in MAPLE, but the deposition of photofragments from the matrix can be avoided. At temperatures above -50 degrees C...

  14. Production of active lysozyme films by matrix assisted pulsed laser evaporation at 355 nm

    DEFF Research Database (Denmark)

    Purice, Andreea; Schou, Jørgen; Kingshott, P.; Dinescu, M.

    decomposition and the protein activity is preserved. The film deposition rate for 1 wt% lysozyme shows a clear maximum of about 1 ng/cm(2) per shot for a moderate fluence of 2 J/cm(2), which is about one-half of the deposition rate from a pressed (100%) lysozyme target. (c) 2007 Elsevier B.V. All rights...

  15. Laser processing of Zinc phthalocyanine thin films prepared by low temperature evaporation

    Czech Academy of Sciences Publication Activity Database

    Fitl, Přemysl; Myslík, V.; Náhlík, J.; Kašpárková, I.; Kopecký, D.; Vrňata, M.; Lančok, Ján; Vysloužil, F.

    Strasbourg: EMRS, 2010. 13 RPIII21. [E- MRS 2010 Spring: Laser processing and diagnostics for micro and nano applications. 07.06.2010-11.06.2010, Strasbourg] Institutional research plan: CEZ:AV0Z10100522 Keywords : Zinc phthalocyanine * gas sensors * thin films Subject RIV: BH - Optics, Masers, Lasers

  16. Surface morphology of thin lysozyme films produced by matrix-assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Purice, Andreea; Schou, Jørgen; Pryds, Nini;

    2007-01-01

    concentration of lysozyme in the ice matrix apparently does not play any significant role for the morphology of the film. The morphology obtained with MAPLE has been compared with results for direct laser irradiation of a pressed lysozyme sample (i.e. pulsed laser deposition (PLD)). (C) 2007 Elsevier B.V. All...

  17. Investigation of elastic and optical properties of electron beam evaporated ZrO2–MgO composite thin films

    International Nuclear Information System (INIS)

    Thin films of composite materials are being progressively explored for achieving tunability in the optical constants for application in multilayer optical devices. In the present study, a set of ZrO2–MgO binary mixed composite thin films have been prepared by reactive electron beam evaporation of solid solution of ZrO2 and MgO at different oxygen partial pressures. Since elastic properties of the thin films are very important for their environmental stability under high power laser application, elastic moduli (indentation moduli) of the films have been measured by atomic force acoustic microscopy measurements. The optical properties especially refractive index of such films has been determined from the optical transmission measurement using an inverse synthesis method, while the density of such films has been measured by grazing incidence X-ray reflectivity. The variation of the elastic moduli of the thin films as a function of oxygen partial pressure used during deposition has been studied and the above variation has been corroborated with the variation of density and refractive index of the thin films. - Highlights: • Indentation modulus of ZrO2–MgO films estimated by atomic force acoustic microscopy • The thin film deposited without oxygen pressure depicts highest indentation modulus. • Indentation modulus of the films decreases monotonically with oxygen pressure. • Correlation between indentation modulus, refractive index and film density established

  18. Effect of H{sup +} irradiation on the optical properties of vacuum evaporated AgInSe{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M.C. Santhosh, E-mail: santhoshmc@nitt.edu [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli, Tamil Nadu 620 015 (India); Pradeep, B. [Solid State Physics Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682 022 (India)

    2009-07-30

    We prepared polycrystalline AgInSe{sub 2} thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. The samples were subjected to the irradiation of 1.26 MeV protons (H{sup +}). The effect of irradiation on the optical properties has been investigated for different doses of H{sup +}. It is observed that the band gap of silver indium selenide thin films decreases gradually with ion irradiation dose.

  19. Effect of argon gas flow rate on properties of film electrodes prepared by thermal vacuum evaporation from synthesized Cu2SnSe3 source

    International Nuclear Information System (INIS)

    This work describes a new technique to enhance photoresponse of metal chalcogenide-based semiconductor film electrodes deposited by thermal vacuum evaporation under argon gas flow from synthesized Cu2SnSe3 sources. SnSe formation with Cu-doped was obtained under higher argon gas flow rate (VA = 25 cm3/min). Higher value of photoresponse was observed for films deposited under VA = 25 cm3/min which was 9.1%. This finding indicates that Cu atoms inside the SnSe film were important to increase carrier concentrations that promote higher photoresponse

  20. Evaporation temperature-tuned physical vapor deposition growth engineering of one-dimensional non-Fermi liquid tetrathiofulvalene tetracyanoquinodimethane thin films

    DEFF Research Database (Denmark)

    Sarkar, I.; Laux, M.; Demokritova, J.;

    2010-01-01

    We describe the growth of high quality tetrathiofulvalene tetracyanoquinodimethane (TTF-TCNQ) organic charge-transfer thin films which show a clear non-Fermi liquid behavior. Temperature dependent angle resolved photoemission spectroscopy and electronic structure calculations show that the growth...... of TTF-TCNQ films is accompanied by the unfavorable presence of neutral TTF and TCNQ molecules. The quality of the films can be controlled by tuning the evaporation temperature of the precursor in physical vapor deposition method. © 2010 American Institute of Physics....

  1. Realization of single-phase BaSi2 films by vacuum evaporation with suitable optical properties and carrier lifetime for solar cell applications

    Science.gov (United States)

    Hara, Kosuke O.; Nakagawa, Yoshihiko; Suemasu, Takashi; Usami, Noritaka

    2015-07-01

    We have realized BaSi2 films by a simple vacuum evaporation technique for solar cell applications. X-ray diffraction analysis shows that single-phase BaSi2 films are formed on alkali-free glass substrates at 500 and 600 °C while impurity phases coexist on quartz or soda-lime glass substrates or at a substrate temperature of 400 °C. The mechanism of film growth is discussed by analyzing the residue on the evaporation boat. An issue on the fabricated films is cracking due to thermal mismatch, as observed by secondary electron microscopy. Optical characterizations by transmittance and reflectance spectroscopy show that the evaporated films have high absorption coefficients, reaching 2 × 104 cm-1 for a photon energy of 1.5 eV, and have indirect absorption edges of 1.14-1.21 eV, which are suitable for solar cells. The microwave-detected photoconductivity decay measurement reveals that the carrier lifetime is approximately 0.027 µs, corresponding to the diffusion length of 0.84 µm, which suggests the potential effective usage of photoexcited carriers.

  2. Film boiling heat transfer characteristics of sodium in droplet evaporation on heated tantalum

    International Nuclear Information System (INIS)

    For gaining background information on possible vapor explosion in a hypothetical core disruptive accident of liquid metal cooled fast breeder reactors, the experiment on the film boiling characteristics of sodium was conducted in association with Leidenfrost phenomenon. In a steel container filled with 1.0bar argon gas, sodium droplets were put on a heated disk and the behavior of droplets was observed through pyrex glass windows by a 35mm camera and a color videotape-recorder. A tantalum disk of 70mm dia. and 30mm height was induction-heated by an oil-cooled coil and a high frequency power supply of 20kHz and 30kW rating. The wall temperature of the disk was measured by a 1.6mm O.D. Ta-sheathed W-5%Re/W-26%Re thermocouple embedded beneath the disk. The experimental conditions were the initial droplet temperature and volume : 400-5000C and about 1.0cm3, the initial tantalum disk temperature : 1390-18900C. The heat flux was estimated from the volumetric reducing rate of droplet due to vaporization, based on photographic observation. The data plots of heat flux, though widely scattering, showed a decreasing trend with the wall superheat in the temperature range of 1390-16000C, while an increasing trend in the range of 1600-18900C. The former range suggests to correspond to the transition boiling region and the latter to the film boiling region. Thus, the minimum film boiling point was roughly estimated to be around 16000C and 45W/cm2. In the film boiling region the plots came slightly above the theoretical prediction. (author)

  3. SHEAR BOND STRENGTHS BETWEEN CERAMIC CORES AND VENEERING CERAMICS OF DENTAL BI-LAYERED CERAMIC SYSTEMS AND THE SENSITIVITY TO THERMOCYCLING

    OpenAIRE

    SUN TING, BDS, DDS; SHAO LONQUAN, DDS, MS; DENG BIN, DDS, MS; WEN NING, DDS, MS

    2012-01-01

    The purpose of this study was to investigate the bond strength between various commercial ceramic core materials and veneering ceramics of dental bi-layered ceramic combinations and the effect of thermocycling. The shear bond strength of four dental bi-layered ceramic combinations (white Cercon, yellow Cercon, white Lava, yellow Lava, IPS E.max) were tested. Metal ceramic combinations were conducted as a control group. Half of each group was subjected to thermocycling. All specimens were ther...

  4. Controlling interfacial curvature in nanoporous silica films formed by evaporation-induced self-assembly from nonionic surfactants. II. Effect of processing parameters on film structure.

    Science.gov (United States)

    Urade, Vikrant N; Bollmann, Luis; Kowalski, Jonathan D; Tate, Michael P; Hillhouse, Hugh W

    2007-04-10

    The double-gyroid phase of nanoporous silica films has been shown to possess facile mass-transport properties and may be used as a mold to fabricate a variety of highly ordered inverse double-gyroid metal and semiconductor films. This phase exists only over a very small region of the binary phase diagram for most surfactants, and it has been very difficult to synthesize metal oxide films with this structure by evaporation-induced self-assembly (EISA). Here, we show the interplay of the key parameters needed to synthesize these structures reproducibly and show that the interfacial curvature may be systematically controlled. Grazing angle of incidence small-angle X-ray scattering (GISAXS) is used to determine the structure and orientation of nanostructured silica films formed by EISA from dilute silica/(poly(ethylene oxide)-b-poly(propylene oxide)-b-alkyl) surfactant solutions. Four different highly ordered film structures are observed by changing only the concentration of the surfactant, the relative humidity during dip-coating, and the aging time of the solution prior to coating. The highly ordered films progress from rhombohedral (Rm) to 2D rectangular (c2m) to double-gyroid (distorted Iad) to lamellar systematically as interfacial curvature decreases. Under all experimental conditions investigated, increasing the aging time of the coating solution was found to decrease the interfacial curvature. In particular, this parameter was critical to being able to synthesize highly ordered, pure-phase double-gyroid films. The key role of the aging time is shown via processing diagrams that map out the interplay between the aging time, composition, and relative humidity. 29Si nuclear magnetic resonance (NMR) spectroscopy and solution-phase small-angle X-ray scattering (SAXS) of the aged coating solutions presented in part I of this series are then used to interpret the effects of aging prior to dip-coating. Specifically, it was found that a predictive model based on volume

  5. Size-dependent structure and magnetic properties of co-evaporated Fe-SiO2 nanoparticle composite film under high magnetic field

    Science.gov (United States)

    Ma, Yonghui; Li, Guojian; Du, Jiaojiao; Li, Mengmeng; Wang, Jianhao; Wang, Qiang

    2016-05-01

    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.

  6. Orientation of CdTe epitaxial films on GaAs(100) grown by vacuum evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Houng Mauphon; Fu Shenli; Jenq Fenqlin (Dept. of Electrical Engineering, National Cheng-Kung Univ., Tainan (Taiwan)); Chen Jiannruey (Dept. of Materials Science and Engineering, National Tsing Hua Univ., Hsinchu (Taiwan))

    1991-08-15

    The growth of (100)- and (111)-oriented CdTe epitaxial layers on (100)-oriented GaAs substrates were investigated. Ar{sup +} plasma bombardment was used to remove the surface oxide layer, while preheating the substrate before evaporation was performed to deplete arsenic on the GaAs substrate surface. Results indicate that the CdTe(100) will grow on GaAs(100) with an oxide layer remaining on the surface. For the GaAs(100) substrate with the oxide layer removed by plasma bombardment, CdTe(100) will grow on the arsenic-depleted GaAs substrate, while CdTe(111) will grow on the GaAs substrate without arsenic depletion. A model is proposed that a tellurium-rich surface is formed on the arsenic-depleted GaAs surface through Ga-Te bonding on which the CdTe(100) will grow, whereas CdTe(111) will grow on a tellurium-poor surface. The photoluminescence investigation conforms to our proposed model. (orig.).

  7. {11-bar 01} twin dislocation structures in evaporated titanium thin films

    International Nuclear Information System (INIS)

    High-resolution transmission electron micrographs of { 11-bar 01} interfacial twin dislocations in Ti thin films are reexamined. Computer simulations of the experimental images were obtained using atomic models deduced by Pond, Bacon and Serra (Phil Mag Letts, 1995). Two twin dislocations were analysed, with step heights of 4 x d(K1) and 2 x d (K1), where d(K1) is the spacing of the { 11-bar 01 } planes. Reasonable agreement with the predicted structures was obtained at about 0.17nm resolution. 10 refs., 2 figs

  8. A study of the electronic processes in evaporated thin films of nickel phthalocyanine

    CERN Document Server

    Anthopoulos, T D

    2003-01-01

    Design and development of electronic devices based on organic semiconductors requires knowledge of the electronic conduction processes that occur within these solids. In this thesis the structural, optical and electrical properties of nickel phthalocyanine (NiPc) are investigated. In particular, various electrical properties of NiPc were studied (to the best of knowledge for the first time) in situ employing a fabrication and characterisation method developed in-house for this particular purpose. Films deposited onto quartz substrates, maintained at room temperature, were identified by X-ray diffractometry to be of the alpha-form. Optical studies of absorption in the ultraviolet (UV) and visible (Vis) spectrum of the same films showed the existence of two absorption bands. The absorption maxima in the Vis and UV were identified as the Q and Soret band, respectively, and were both attributed to pi-> pi sup * transition. Analysis of optical data yielded a value of 2.32 eV for the optical energy band gap (E sub ...

  9. Plasmonics and single-molecule detection in evaporated silver-island films

    Energy Technology Data Exchange (ETDEWEB)

    Moula, G.; Aroca, R.F. [Materials and Surface Science Group, University of Windsor, Ontario (Canada); Rodriguez-Oliveros, R.; Sanchez-Gil, J.A. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain); Albella, P. [Centro de Fisica de Materiales (CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), 20018 Donostia, San Sebastian (Spain)

    2012-11-15

    The plasmonic origin of surface-enhanced Raman scattering (SERS) leads to the concept of hotspots and plasmon coupling that can be realized in the interstitial regions, or on specially engineered, silver and gold nanostructures. It is also possible to achieve spatial locations of high local field or hotspots on silver-island films (SIF) allowing single-molecule detection (SMD). When a single monomolecular layer coating the SIFs contains dye molecules dispersed in it, single-molecule impurities, (with an average of one hundred dye molecules in 1 {mu}m{sup 2}, which is the field of view of the micro-Raman system), SMD is observed as a rare statistical event. Here, the SMD results for silver-island films are presented, with the same nominal mass thickness, but differing in the localized surface plasmon resonance that is a function of the temperature of substrate during deposition. A blue-shifted plasmon can be seen as a decrease in plasmon coupling for deposition at higher temperature. A simple two-particle model for localized plasmon resonance coupling calculations, including the shape and substrate effects seems to explain the trend of observations. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Properties of annealed indium-rich In sub 2 O sub 3 film deposited by plasma enhanced reactive evaporation (PERE) technique

    International Nuclear Information System (INIS)

    Indium rich In sub 3 O sub 3 film is grown by plasma enhanced reactive evaporation (PERE) technique. The film is deposited onto glass and silicon substrate at ∼ 300 degree C. The flowrates of N sub 2 O in He as the reacting gases are 47.65 sccm and 11.65 sccm respectively. Film thicknesses of ∼ 5000 A are obtained, as measured from Tolansky and ellipsometric methods. The optical, electrical and structural properties of the film are studied at different annealing temperatures in the 100 degree C to 500 degree C range in oxygen for one hour. The refractive index calculated at a wavelength of 632.8 nm is measured by 4-point probe, is ∼ 20 Ω/□. The structure of the film as illustrated from XRD analysis shows predominant (110) In and (222) In sub 2 O sub 3 peaks, where the former decreases with increasing annealing temperatures

  11. A study on the nonlinear microwave electrodynamic response of e-beam evaporated MgB{sub 2} superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Andreone, A [I.N.F.M. and Dipartimento Scienze Fisiche, Universita Federico II, Napoles (Italy); Gennaro, E Di [I.N.F.M. and Dipartimento Scienze Fisiche, Universita Federico II, Napoles (Italy); Lamura, G [I.N.F.M. and Dipartimento Scienze Fisiche, Universita Federico II, Napoles (Italy); Salluzzo, M [I.N.F.M. and Dipartimento Scienze Fisiche, Universita Federico II, Napoles (Italy); Purnell, A [Imperial College of Science, Technology and Medicine, London (United Kingdom); Cohen, L F [Imperial College of Science, Technology and Medicine, London (United Kingdom); Hao, L [National Physical Laboratory, Teddington, Middlesex (United Kingdom); Gallop, J [National Physical Laboratory, Teddington, Middlesex (United Kingdom); Cantoni, C [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Paranthaman, M [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2003-02-01

    We present a study on the temperature and field dependence of the microwave surface impedance Z{sub s} in thin films of the superconducting MgB{sub 2} compound. Samples were prepared by e-beam evaporation of boron on r-plane sapphire followed by an ex situ annealing in Mg vapour. Critical temperature values range between 26 and 38 K. Surface impedance measurements (Z{sub s} = R{sub s} + iX{sub s}) were performed from 2 K close to T{sub c} in the microwave region up to 20 GHz via parallel plate or dielectrically loaded resonators in 'symmetric' (two MgB{sub 2} films) and asymmetric (an MgB{sub 2} film and a commercial YBCO control film) configurations. At high microwave power, frequency domain measurements show a characteristic signature associated with weak links and this appears to be the limiting factor governing the performance of these films.

  12. Structure and magnetic properties of Fe doped In{sub 2}O{sub 3} thin films prepared by electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, N. Sai; Kaleemulla, S., E-mail: skaleemulla@gmail.com; Rao, N. Madhusudhana; Krishnamoorthi, C.; Begam, M. Rigana [Thin Films Laboratory, School of Advanced Sciences, VIT University, Vellore – 632014 (India); Amarendra, G. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); UGC-DAE-CSR, Kalpakkam Node, Kokilamedu, Tamilnadu -603104 (India)

    2015-06-24

    Pure and Fe (7 at.%) doped In{sub 2}O{sub 3} thin films were grown onto the glass substrates by electron beam evaporation technique. The structural and magnetic properties of the pure and Fe doped In{sub 2}O{sub 3} thin films have been studied. The undoped and Fe doped In{sub 2}O{sub 3} thin films shown ferromagnetic property at room temperature. A magnetization of 24 emu/cm{sup 3} was observed for pure In{sub 2}O{sub 3} thin films. The magnetization of 38.23 emu/cm{sup 3} was observed for the Fe (7 at.%) doped In{sub 2}O{sub 3} thin films.

  13. Copper tin sulfide (CTS) absorber thin films obtained by co-evaporation: Influence of the ratio Cu/Sn

    International Nuclear Information System (INIS)

    Highlights: • Copper tin sulfide (CTS) thin films were grown by co-evaporation at different Cu/Sn atomic ratios. • Smooth Cu2SnS3 layers with large grains are obtained at Cu/Sn ⩾ 1.5 and T ⩾ 350 °C. • At 450 °C, the cubic Cu2SnS3 phase changes to tetragonal phase. • Cu2SnS3 presents suitable optical and electrical properties for use as photovoltaic absorbers. - Abstract: Copper tin sulfide thin films have been grown on soda-lime glass substrates from the elemental constituents by co-evaporation. The synthesis was performed at substrate temperatures of 350 °C and 450 °C and different Cu/Sn ratios, adjusting the deposition time in order to obtain thicknesses above 1000 nm. The evolution of the morphological, structural, chemical, optical and electrical properties has been analyzed as a function of the substrate temperature and the Cu/Sn ratio. For the samples with Cu/Sn ⩽ 1, Cu2Sn3S7 and Cu2SnS3 have been observed by XRD. Increasing the Cu/Sn to 1.5, the Cu2SnS3 phase was the majority, being the formation completed at Cu/Sn ratio around 2. The increment of the substrate temperature leads to a change of cubic structure to tetragonal of the Cu2SnS3 phase. The chemical treatment with KCN was effective to eliminate CuS excess detected in the samples with Cu/Sn > 2.2. The samples with Cu2SnS3 structure show a band gap energy increasing from 0.9 to 1.25 eV and an electrical resistivity decreasing from 7 ∗ 10−2 Ω cm to 3 ∗ 10−3 Ω cm when the Cu/Sn atomic ratio increases from 1.5 to 2.2

  14. Copper tin sulfide (CTS) absorber thin films obtained by co-evaporation: Influence of the ratio Cu/Sn

    Energy Technology Data Exchange (ETDEWEB)

    Robles, V., E-mail: victor.robles@ciemat.es; Trigo, J.F.; Guillén, C.; Herrero, J.

    2015-09-05

    Highlights: • Copper tin sulfide (CTS) thin films were grown by co-evaporation at different Cu/Sn atomic ratios. • Smooth Cu{sub 2}SnS{sub 3} layers with large grains are obtained at Cu/Sn ⩾ 1.5 and T ⩾ 350 °C. • At 450 °C, the cubic Cu{sub 2}SnS{sub 3} phase changes to tetragonal phase. • Cu{sub 2}SnS{sub 3} presents suitable optical and electrical properties for use as photovoltaic absorbers. - Abstract: Copper tin sulfide thin films have been grown on soda-lime glass substrates from the elemental constituents by co-evaporation. The synthesis was performed at substrate temperatures of 350 °C and 450 °C and different Cu/Sn ratios, adjusting the deposition time in order to obtain thicknesses above 1000 nm. The evolution of the morphological, structural, chemical, optical and electrical properties has been analyzed as a function of the substrate temperature and the Cu/Sn ratio. For the samples with Cu/Sn ⩽ 1, Cu{sub 2}Sn{sub 3}S{sub 7} and Cu{sub 2}SnS{sub 3} have been observed by XRD. Increasing the Cu/Sn to 1.5, the Cu{sub 2}SnS{sub 3} phase was the majority, being the formation completed at Cu/Sn ratio around 2. The increment of the substrate temperature leads to a change of cubic structure to tetragonal of the Cu{sub 2}SnS{sub 3} phase. The chemical treatment with KCN was effective to eliminate CuS excess detected in the samples with Cu/Sn > 2.2. The samples with Cu{sub 2}SnS{sub 3} structure show a band gap energy increasing from 0.9 to 1.25 eV and an electrical resistivity decreasing from 7 ∗ 10{sup −2} Ω cm to 3 ∗ 10{sup −3} Ω cm when the Cu/Sn atomic ratio increases from 1.5 to 2.2.

  15. A study of the electronic processes in evaporated thin films of nickel phthalocyanine

    International Nuclear Information System (INIS)

    Design and development of electronic devices based on organic semiconductors requires knowledge of the electronic conduction processes that occur within these solids. In this thesis the structural, optical and electrical properties of nickel phthalocyanine (NiPc) are investigated. In particular, various electrical properties of NiPc were studied (to the best of author's knowledge for the first time) in situ employing a fabrication and characterisation method developed in-house for this particular purpose. Films deposited onto quartz substrates, maintained at room temperature, were identified by X-ray diffractometry to be of the α-form. Optical studies of absorption in the ultraviolet (UV) and visible (Vis) spectrum of the same films showed the existence of two absorption bands. The absorption maxima in the Vis and UV were identified as the Q and Soret band, respectively, and were both attributed to π→π* transition. Analysis of optical data yielded a value of 2.32 eV for the optical energy band gap (EgO).The dark current-voltage characteristics at fixed temperatures, and the variation of current as a function of temperature at constant bias levels, have also been established. Results were analysed in the framework of band theory to elucidate various electronic parameters. The dark conductivity of NiPc films was found to be strongly dependent upon the type of metal contacts, electric field and ambient conditions. For symmetric gold electrodes, ohmic behaviour at low-voltages and space charge limited conduction (SCLC) at higher-voltages, were identified. The latter, was found to be controlled by an exponential trap distribution above the valence band edge. A number of electronic parameters, namely, relative permittivity (εr), hole mobility (μ), activation energies (EA), thermally generated hole concentrations (p0), concentration of traps per unit energy range at the valence band edge (P0), characteristic temperature parameter of trap distribution (Tt) and total

  16. In-situ growth of a CdS window layer by vacuum thermal evaporation for CIGS thin film solar cell applications

    International Nuclear Information System (INIS)

    Highly crystalline and transparent CdS films are grown by utilizing the vacuum thermal evaporation (VTE) method. The structural, surface morphological, and optical properties of the films are studied and compared with those prepared by chemical bath deposition (CBD). It is found that the films deposited at a high substrate temperature (200 °C) have a preferential orientation along (002) which is consistent with CBD-grown films. Absorption spectra reveal that the films are highly transparent and the optical band gap values are found to be in a range of 2.44 eV–2.56 eV. CuIn1−xGaxSe2 (CIGS) solar cells with in-situ VTE-grown CdS films exhibit higher values of Voc together with smaller values of Jsc than those from CBD. Eventually the conversion efficiency and fill factor become slightly better than those from the CBD method. Our work suggests that the in-situ thermal evaporation method can be a competitive alternative to the CBD method, particularly in the physical- and vacuum-based CIGS technology. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  17. The secondary electron yield of TiZr and TiZrV non evaporable getter thin film coatings

    CERN Document Server

    Scheuerlein, C; Hilleret, Noël; Taborelli, M

    2001-01-01

    The secondary electron yield (SEY) of two different non evaporable getter (NEG) samples has been measured 'as received' and after thermal treatment. The investigated NEGs are TiZr and TiZrV thin film coatings of 1 mm thickness, which are sputter deposited onto copper substrates. The maximum SEY dmax of the air exposed TiZr and TiZrV coating decreases from above 2.0 to below 1.1 during a 2 hour heat treatment at 250 °C and 200 °C, respectively. Saturating an activated TiZrV surface under vacuum with the gases typically present in ultra high vacuum systems increases dmax by about 0.1. Changes in elemental surface composition during the applied heat treatments were monitored by Auger electron spectroscopy (AES). After activation carbon, oxygen and chlorine were detected on the NEG surfaces. The potential of AES for detecting the surface modifications which cause the reduction of SE emission during the applied heat treatments is critically discussed.

  18. YBCO films grown by reactive co-evaporation on simplified IBAD-MgO coated conductor templates

    International Nuclear Information System (INIS)

    We demonstrate coated conductors fabricated by reactive co-evaporation of YBa2Cu3Oy (YBCO) by cyclic deposition and reaction (RCE-CDR) on ion-beam-assisted-deposition- (IBAD-) textured templates simplified by the elimination of the epitaxial buffer layer. Hastelloy substrates, both polished and unpolished, were used as a starting material for the IBAD templates. Y2O3 bed layers were then deposited followed by IBAD-textured MgO and a thin homoepitaxial MgO layer. The MgO-terminated templates were used for direct deposition of YBCO by RCE-CDR. Critical current densities obtained for the undoped YBCO material are comparable to the best values measured previously with the use of LaMnO3 or SrTiO3 epitaxial buffer layers and state-of-the-art coated conductor results. The structural characterization data indicate a well oriented YBCO film with a robust template. Electrical measurements also indicate no weak links and a typical magnetic field behavior of undoped YBCO, characterized by a low density of naturally occurring strong pinning centers and correlations along the ab direction.

  19. Optical and structural investigations of self-assembled Ge/Si bi-layer containing Ge QDs

    Energy Technology Data Exchange (ETDEWEB)

    Samavati, Alireza, E-mail: alireza.samavati@yahoo.com [Ibn Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Othaman, Z., E-mail: zulothaman@gmail.com [Ibn Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Ghoshal, S.K.; Dousti, M.R. [Advanced Optical Material Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

    2014-10-15

    We report the influence of Si spacer thickness variation (10–40 nm) on structural and optical properties of Ge quantum dots (QDs) in Ge/Si(1 0 0) bi-layer grown by radio frequency magnetron sputtering. AFM images reveal the spacer dependent width, height, root mean square roughness and number density of QDs vary in the range of ∼12–25 nm, ∼2–6 nm, ∼1.95–1.05 nm and ∼0.55×10{sup 11}–2.1×10{sup 11} cm{sup −2}, respectively. XRD patterns exhibit the presence of poly-oriented structures of Ge with preferred growth along (1 1 1) direction accompanied by a reduction in strain from 4.9% to 1.2% (estimated from Williamson–Hall plot) due to bi-layering. The room temperature luminescence displays strong blue–violet peak associated with a blue shift as much as 0.05 eV upon increasing the thickness of Si spacer. This shift is attributed to the quantum size effect, the material intermixing and the strain mediation. Raman spectra for both mono and bi-layer samples show intense Ge–Ge optical phonon mode that is shifted towards higher frequency. Furthermore, the first order features of Raman spectra affirm the occurrence of interfacial intermixing and phase formation during deposition. The excellent features of the results suggest that our systematic method may constitute a basis for the tunable growth of Ge QDs suitable in nanophotonics. - Highlights: • High quality bilayered hetero-structure Ge/Si using economic and easy rf magnetron sputtering fabrication method. • The role of phonon-confinement and strain relaxation mechanisms. • Influence of bilayering on evolutionary growth dynamics. • Band gap shift of visible PL upon bilayering.

  20. Thickness and annealing effects on thermally evaporated InZnO thin films for gas sensors and blue, green and yellow emissive optical devices

    Science.gov (United States)

    Sugumaran, Sathish; Jamlos, Mohd Faizal; Ahmad, Mohd Noor; Bellan, Chandar Shekar; Sivaraj, Manoj

    2016-08-01

    Indium zinc oxide (InZnO) thin films with thicknesses of 100 nm and 200 nm were deposited on glass plate by thermal evaporation technique. Fourier transform infrared spectra showed a strong metal-oxide bond. X-ray diffraction patterns revealed amorphous nature for as-deposited film whereas polycrystalline structure for annealed films. Scanning electron microscope images showed a uniform distribution of spherical shape grains. Grain size was found to be higher for 200 nm film than 100 nm film. The presence of elements (In, Zn and O) was confirmed from energy dispersive X-ray analysis. Photoluminescence study of 200 nm film showed a blue, blue-green and blue-yellow emission whereas 100 nm film showed a broad green and green-yellow emissions. Both 100 nm and 200 nm films showed good oxygen sensitivity from room temperature to 400 °C. The observed optical and sensor results indicated that the prepared InZnO films are highly potential for room temperature gas sensor and blue, green and yellow emissive opto-electronic devices.

  1. Effect of annealing on the structural and optical properties of (3 1 1)B GaAsBi layers

    International Nuclear Information System (INIS)

    The influence of post-growth annealing on the microstructure and photoluminescence (PL) of GaAsBi alloys grown on (3 1 1)B GaAs is analyzed. Conventional transmission electron microscopy (TEM) performed on as-grown samples evidence the presence of structural defects and a mosaic structure in the GaAsBi layer. A sequence of stacking faults at regions close to the GaAs/GaAsBi interface are observed in high resolution TEM images. After annealing at 473 K during 3 h the mosaic structure disappears, the presence of defects is reduced and the PL peak intensely enhances.

  2. Efficiency enhancement of Sb2Se3 thin-film solar cells by the co-evaporation of Se and Sb2Se3

    Science.gov (United States)

    Li, Zhiqiang; Zhu, Hongbing; Guo, Yuting; Niu, Xiaona; Chen, Xu; Zhang, Chong; Zhang, Wen; Liang, Xiaoyang; Zhou, Dong; Chen, Jingwei; Mai, Yaohua

    2016-05-01

    In this work, we present an alternative route to supply excessive selenium (Se) for the deposition of Sb2Se3 thin films by the co-evaporation of Se and Sb2Se3. Scanning electron microscopy (SEM) images showed that additional Se modified the growth process and surface morphology of Sb2Se3 thin films. X-ray diffraction (XRD) patterns confirmed that this co-evaporation process enhanced the beneficiary preferred orientations, and capacitance–voltage (C–V) measurement showed that the carrier concentration of the Sb2Se3 absorber increased with the additional evaporation of Se. Accordingly, the efficiency of the devices employing co-evaporated Sb2Se3 absorber layers increased significantly from 2.1 to 3.47% with a open-circuit voltage (V OC) of 364 mV, a short-circuit current density (J SC) of 23.14 mA/cm2, and a fill factor (FF) of 41.26%.

  3. Wetting and Photocatalytic Properties of TiO2 Nanotube Arrays Prepared via Anodic Oxidation of E-Beam Evaporated Ti Thin Films

    Directory of Open Access Journals (Sweden)

    Soon Wook Kim

    2015-01-01

    Full Text Available TiO2 nanotube arrays (TNAs are fabricated on quartz substrate by anodizing E-beam evaporated Ti films. E-beam evaporated Ti films are directly anodized at various anodizing voltages ranging from 20 to 45 V and their morphological, wetting, and photocatalytic properties are examined. The photocatalytic activity of the prepared TNAs is evaluated by the photodecomposition of methylene blue under UV illumination. The TNAs prepared at an anodizing voltage of 30 V have a high roughness of 30.1 nm and a low water contact angle of 7.5°, resulting in a high photocatalytic performance. The surface roughness of the TNAs is found to correlate inversely with the water contact angle. High roughness (i.e., high surface area, which leads to high hydrophilicity, is desirable for effective photocatalytic activity.

  4. Preparation of PbTiO3 Films Utilizing Self-Control Mechanism of Stoichiometric Composition in Dual-Beam Vacuum Evaporation Method

    Science.gov (United States)

    Ueno, Satoshi; Ishiwara, Hiroshi

    1992-09-01

    Optimum conditions for preparing PbTiO3 films on Si and SrTiO3 substrates are investigated in the dual-beam vacuum evaporation method using PbO and TiO2. It has been found that tetragonal PbTiO3 films are formed on Si substrates at temperatures ranging from 550°C to 600°C, and that the stoichiometric composition of the films is easily obtained at 600°C by supplying excess PbO molecules to the substrate. It has also been found that PbTiO3 films grow epitaxially on SrTiO3 substrates at temperatures around 550°C.

  5. Effects of precursor evaporation temperature on the properties of the yttrium oxide thin films deposited by microwave electron cyclotron resonance plasma assisted metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Yttrium oxide thin films are deposited using indigenously developed metal organic precursor (2,2,6,6-tetra methyl-3,5-hepitane dionate) yttrium, commonly known as Y(thd)3 (synthesized by ultrasound method). Microwave electron cyclotron resonance plasma assisted metal organic chemical vapor deposition process was used for these depositions. Depositions were carried out at a substrate temperature of 350 oC with argon to oxygen gas flow rates fixed to 1 sccm and 10 sccm respectively throughout the experiments. The precursor evaporation temperature (precursor temperature) was varied over a range of 170-275 oC keeping all other parameters constant. The deposited coatings are characterized by X-ray photoelectron spectroscopy, glancing angle X-ray diffraction and infrared spectroscopy. Thickness and refractive index of the coatings are measured by the spectroscopic ellipsometry. Hardness and elastic modulus of the films are measured by load depth sensing nanoindentation technique. C-Y2O3 phase is deposited at lower precursor temperature (170 oC). At higher temperature (220 oC) cubic yttrium oxide is deposited with yttrium hydroxide carbonate as a minor phase. When the temperature of the precursor increased (275 oC) further, hexagonal Y2O3 with some multiphase structure including body centered cubic yttria and yttrium silicate is observed in the deposited film. The properties of the films drastically change with these structural transitions. These changes in the film properties are correlated here with the precursor evaporation characteristics obtained at low pressures.

  6. Effect of Annealing Temperature on CuInSe2/ZnS Thin-Film Solar Cells Fabricated by Using Electron Beam Evaporation

    Directory of Open Access Journals (Sweden)

    H. Abdullah

    2013-01-01

    Full Text Available CuInSe2 (CIS thin films are successfully prepared by electron beam evaporation. Pure Cu, In, and Se powders were mixed and ground in a grinder and made into a pellet. The pallets were deposited via electron beam evaporation on FTO substrates and were varied by varying the annealing temperatures, at room temperature, 250°C, 300°C, and 350°C. Samples were analysed by X-ray diffractometry (XRD for crystallinity and field-emission scanning electron microscopy (FESEM for grain size and thickness. I-V measurements were used to measure the efficiency of the CuInSe2/ZnS solar cells. XRD results show that the crystallinity of the films improved as the temperature was increased. The temperature dependence of crystallinity indicates polycrystalline behaviour in the CuInSe2 films with (1 1 1, (2 2 0/(2 0 4, and (3 1 2/(1 1 6 planes at 27°, 45°, and 53°, respectively. FESEM images show the homogeneity of the CuInSe2 formed. I-V measurements indicated that higher annealing temperatures increase the efficiency of CuInSe2 solar cells from approximately 0.99% for the as-deposited films to 1.12% for the annealed films. Hence, we can conclude that the overall cell performance is strongly dependent on the annealing temperature.

  7. Controlling precursor stability and evaporation through molecular design. Pseudo single source precursor approach to MOCVD SrTiO3 thin films

    International Nuclear Information System (INIS)

    Strontium titanate SrTiO3 thin films have attracted interest as a possible gate dielectric material. Preparation of its high quality coatings is hindered by difference in volatility of the homometallic precursors - strontium beta-diketonates and titanium alkoxides. The only earlier known single-source precursor, a sec-alkoxide derivative Sr2Ti2(thd)4(OiPr)8, has limited volatility. Bimetallic primary alkyl chain complexes, Sr4Ti2O(thd)4(OR)10(ROH)2, R = Et, nPr, are stable and volatile, but possess a wrong composition. Highly volatile precursor Sr2Ti2(thd)4(OiBu)8 has been prepared using an iso-alkoxide, combining proper ligand size with the sterical requirements, and characterized by multivariate evaporation analysis. Its evaporation is associated with complete decomposition into homometallic species, which, however, are evaporated in a single step. This permits to successfully use this novel precursor for SrTiO3 thin film deposition by DLI-MOCVD technique in a sufficiently broad established temperature range. Using optimized experimental conditions, 100 nm thick strontium titanate films with high permittivity have been successfully obtained on (1 0 0) Si.

  8. Schottky barrier contrasts in single and bi-layer graphene contacts for MoS2 field-effect transistors

    Science.gov (United States)

    Du, Hyewon; Kim, Taekwang; Shin, Somyeong; Kim, Dahye; Kim, Hakseong; Sung, Ji Ho; Lee, Myoung Jae; Seo, David H.; Lee, Sang Wook; Jo, Moon-Ho; Seo, Sunae

    2015-12-01

    We have investigated single- and bi-layer graphene as source-drain electrodes for n-type MoS2 transistors. Ti-MoS2-graphene heterojunction transistors using both single-layer MoS2 (1M) and 4-layer MoS2 (4M) were fabricated in order to compare graphene electrodes with commonly used Ti electrodes. MoS2-graphene Schottky barrier provided electron injection efficiency up to 130 times higher in the subthreshold regime when compared with MoS2-Ti, which resulted in VDS polarity dependence of device parameters such as threshold voltage (VTH) and subthreshold swing (SS). Comparing single-layer graphene (SG) with bi-layer graphene (BG) in 4M devices, SG electrodes exhibited enhanced device performance with higher on/off ratio and increased field-effect mobility (μFE) due to more sensitive Fermi level shift by gate voltage. Meanwhile, in the strongly accumulated regime, we observed opposing behavior depending on MoS2 thickness for both SG and BG contacts. Differential conductance (σd) of 1M increases with VDS irrespective of VDS polarity, while σd of 4M ceases monotonic growth at positive VDS values transitioning to ohmic-like contact formation. Nevertheless, the low absolute value of σd saturation of the 4M-graphene junction demonstrates that graphene electrode could be unfavorable for high current carrying transistors.

  9. Complex Boron Redistribution in P+ Doped-polysilicon / Nitrogen Doped Silicon Bi-layers during Activation Annealing

    Science.gov (United States)

    Abadli, S.; Mansour, F.; Perrera, E. Bedel

    We have investigated and modeled the complex phenomenon of boron (B) redistribution process in strongly doped silicon bilayers structure. A one-dimensional two stream transfer model well adapted to the particular structure of bi- layers and to the effects of strong-concentrations has been developed. This model takes into account the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method, using in-situ nitrogen- doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P+) layer. To avoid long redistributions, thermal annealing was carried out at relatively lowtemperatures (600 °C and 700 °C) for various times ranging between 30 minutes and 2 hours. The good adjustment of the simulated profiles with the experimental secondary ion mass spectroscopy (SIMS) profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders kinetics.

  10. Schottky barrier contrasts in single and bi-layer graphene contacts for MoS2 field-effect transistors

    International Nuclear Information System (INIS)

    We have investigated single- and bi-layer graphene as source-drain electrodes for n-type MoS2 transistors. Ti-MoS2-graphene heterojunction transistors using both single-layer MoS2 (1M) and 4-layer MoS2 (4M) were fabricated in order to compare graphene electrodes with commonly used Ti electrodes. MoS2-graphene Schottky barrier provided electron injection efficiency up to 130 times higher in the subthreshold regime when compared with MoS2-Ti, which resulted in VDS polarity dependence of device parameters such as threshold voltage (VTH) and subthreshold swing (SS). Comparing single-layer graphene (SG) with bi-layer graphene (BG) in 4M devices, SG electrodes exhibited enhanced device performance with higher on/off ratio and increased field-effect mobility (μFE) due to more sensitive Fermi level shift by gate voltage. Meanwhile, in the strongly accumulated regime, we observed opposing behavior depending on MoS2 thickness for both SG and BG contacts. Differential conductance (σd) of 1M increases with VDS irrespective of VDS polarity, while σd of 4M ceases monotonic growth at positive VDS values transitioning to ohmic-like contact formation. Nevertheless, the low absolute value of σd saturation of the 4M-graphene junction demonstrates that graphene electrode could be unfavorable for high current carrying transistors

  11. Reinforcement of Mono- and Bi-layer Poly(Ethylene Glycol) Hydrogels with a Fibrous Collagen Scaffold.

    Science.gov (United States)

    Kinneberg, K R C; Nelson, A; Stender, M E; Aziz, A H; Mozdzen, L C; Harley, B A C; Bryant, S J; Ferguson, V L

    2015-11-01

    Biomaterial-based tissue engineering strategies hold great promise for osteochondral tissue repair. Yet significant challenges remain in joining highly dissimilar materials to achieve a biomimetic, mechanically robust design for repairing interfaces between soft tissue and bone. This study sought to improve interfacial properties and function in a bi-layer hydrogel interpenetrated with a fibrous collagen scaffold. 'Soft' 10% (w/w) and 'stiff' 30% (w/w) PEGDM was formed into mono- or bi-layer hydrogels possessing a sharp diffusional interface. Hydrogels were evaluated as single-(hydrogel only) or multi-phase (hydrogel + fibrous scaffold penetrating throughout the stiff layer and extending >500 μm into the soft layer). Including a fibrous scaffold into both soft and stiff mono-layer hydrogels significantly increased tangent modulus and toughness and decreased lateral expansion under compressive loading. Finite element simulations predicted substantially reduced stress and strain gradients across the soft-stiff hydrogel interface in multi-phase, bilayer hydrogels. When combining two low moduli constituent materials, composites theory poorly predicts the observed, large modulus increases. These results suggest material structure associated with the fibrous scaffold penetrating within the PEG hydrogel as the major contributor to improved properties and function-the hydrogel bore compressive loads and the 3D fibrous scaffold was loaded in tension thus resisting lateral expansion. PMID:26001970

  12. Structural, optical and electrical properties of CuIn{sub 5}S{sub 8} thin films grown by thermal evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Gannouni, M., E-mail: gm_mounir@yahoo.fr [Laboratoire de Photovoltaique et Materiaux Semi-conducteurs -ENIT BP 37, Le belvedere 1002-Tunis (Tunisia); Kanzari, M. [Laboratoire de Photovoltaique et Materiaux Semi-conducteurs -ENIT BP 37, Le belvedere 1002-Tunis (Tunisia)

    2011-05-19

    Highlights: > In this work, thin films of CuIn{sub 5}S{sub 8} were successfully deposited onto glass substrates by thermal evaporation and annealed in air. > Post-depositional annealing effects on structural, optical and electrical properties of thermal evaporated CuIn{sub 5}S{sub 8} thin films were studied. > The results reported in this work make this material attractive as an absorber material in solar cells applications. - Abstract: Stoichiometric compound of copper indium sulfur (CuIn{sub 5}S{sub 8}) was synthesized by direct reaction of high purity elemental copper, indium and sulfur in an evacuated quartz tube. The phase structure of the synthesized material revealed the cubic spinel structure. The lattice parameter (a) of single crystals was calculated to be 10.667 A. Thin films of CuIn{sub 5}S{sub 8} were deposited onto glass substrates under the pressure of 10{sup -6} Torr using thermal evaporation technique. CuIn{sub 5}S{sub 8} thin films were then thermally annealed in air from 100 to 300 deg. C for 2 h. The effects of thermal annealing on their physico-chemical properties were investigated using X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), optical transmission and hot probe method. XRD studies of CuIn{sub 5}S{sub 8} thin films showed that as-deposited films were amorphous in nature and transformed into polycrystalline spinel structure with strong preferred orientation along the (3 1 1) plane after the annealing at 200 deg. C. The composition is greatly affected by thermal treatment. From the optical transmission and reflection, an important absorption coefficient exceeds 10{sup 4} cm{sup -1} was found. As increasing the annealing temperature, the optical energy band gap decreases from 1.83 eV for the as-deposited films to 1.43 eV for the annealed films at 300 deg. C. It was found that CuIn{sub 5}S{sub 8} thin film is an n-type semiconductor at 300 deg. C.

  13. Structural, morphological, gas sensing and photocatalytic characterization of MoO3 and WO3 thin films prepared by the thermal vacuum evaporation technique

    Science.gov (United States)

    Arfaoui, A.; Touihri, S.; Mhamdi, A.; Labidi, A.; Manoubi, T.

    2015-12-01

    Thin films of molybdenum trioxide and tungsten trioxide were deposited on glass substrates using a simplified thermal evaporation under vacuum method monitored by heat treatment in flowing oxygen at 500 °C for 1 h. The structural and morphological properties of the films were investigated using X-ray diffraction, Raman spectroscopy, atomic force microscopy and scanning electron microscopy. The X-ray diffraction analysis shows that the films of MoO3 and WO3 were well crystallized in orthorhombic and monoclinic phase respectively with the crystallites preferentially oriented toward (2 0 0) direction parallel a-axis for both samples. In literature, we have shown in previous papers that structural and surface morphology of metal thin films play an important role in the gas detection mechanism. In this article, we have studied the response evolution of MoO3 and WO3 thin films sensors ethanol versus time, working temperature and the concentration of the ethanol. It was found that these films had high sensitivity to ethanol, which made them as a good candidate for the ethanol sensor. Finally, the photocatalytic activity of the samples was evaluated with respect to the degradation reaction of a wastewater containing methylene blue (MB) under UV-visible light irradiation. The molybdenum trioxide exhibits a higher degradation rate than the tungsten trioxide thin films under similar experimental conditions.

  14. Study of temperature dependence and angular distribution of poly(9,9-dioctylfluorene) polymer films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

    International Nuclear Information System (INIS)

    Poly(9,9-dioctylfluorene) (PFO) polymer films were deposited by matrix-assisted pulsed laser evaporation (MAPLE) technique. The polymer was diluted (0.5 wt%) in tetrahydrofuran and, once cooled to liquid nitrogen temperature, it was irradiated with a KrF excimer laser. 10,000 laser pulses were used to deposit PFO films on Si substrates at different temperatures (-16, 30, 50 and 70 deg. C). One PFO film was deposited with 16,000 laser pulses at a substrate temperature of 50 deg. C. The morphology, optical and structural properties of the films were investigated by SEM, AFM, PL and FTIR spectroscopy. SEM inspection showed different characteristic features on the film surface, like deflated balloons, droplets and entangled polymer filaments. The roughness of the films was, at least partially, controlled by substrate heating, which however had the effect to reduce the deposition rate. The increase of the laser pulse number modified the target composition and increased the surface roughness. The angular distribution of the material ejected from the target confirmed the forward ejection of the target material. PFO films presented negligible modification of the chemical structure respect to the bulk material.

  15. Cu2ZnSnSe4 Thin Films by Selenization of Simultaneously Evaporated Sn-Zn-Cu Metallic Lays for Photovoltaic Applications

    Science.gov (United States)

    Shao, Lexi; Zhang, Jun; Zou, Changwei; Xie, Wei

    Cu2ZnSnSe4 (CZTSe) thin films were prepared by selenization of simultaneously evaporated metallic Cu-Zn-Sn on soda lime glass (SLG) substrates. The selenization were performed in elemental selenium vapor ambient at 450 °C for 1.5 h using Argon as the carrier gas. The compositions and structural properties of the films were characterized by using EDS, XRD, and Raman, respectively. The results show that the synthesized CZTSe thin films are nearly stoichiometric and single-phase with a kesterite structure. The measurement for electrical and optical properties indicated that a high absorption coefficient of 104 cm-1 and a low resistivity of 30 Ωcm are obtained. The optical band-gap energy of the CZTSe thin film can be fitted to be as 1.52 eV, which closes to the optimum value for solar cell absorber. The preparation processing for CZTSe developed in this woek is more attractive than others reported in the industrialization applications because the atomic ratio of Cu:Sn:Zn in the precursor can be easily controlled by adjusting the ratio of the evaporation sources, meanwhile, it is more suitable for large-scale production.

  16. In{sub 6}Se{sub 7} thin films by heating thermally evaporated indium and chemical bath deposited selenium multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ornelas, R.E.; Avellaneda, D. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon-66450 (Mexico); Shaji, S. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon-66450 (Mexico); Universidad Autonoma de Nuevo Leon-CIIDIT, Apodaca, N.L (Mexico); Castillo, G.A.; Roy, T.K. Das [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon-66450 (Mexico); Krishnan, B., E-mail: kbindu_k@yahoo.com [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon-66450 (Mexico); Universidad Autonoma de Nuevo Leon-CIIDIT, Apodaca, N.L (Mexico)

    2012-05-15

    Indium selenide (In{sub 6}Se{sub 7}) thin films were prepared via selenization of thermally evaporated indium thin films by dipping in sodium selenosulphate solution followed by annealing in nitrogen atmosphere. First, indium was thermally evaporated on glass substrate. Then, the indium coated glass substrates were dipped in a solution containing 80 ml 0.125 M sodium selenosulphate and 1.5 ml dilute acetic acid (25%) for 5 min. Glass/In-Se layers were annealed at 200-400 Degree-Sign C in nitrogen atmosphere (0.1 Torr) for 30 min. X-ray diffraction studies showed the formation of monoclinic In{sub 6}Se{sub 7}. Morphology of the thin films formed at different conditions was analyzed using Scanning electron microscopy. The elemental analysis was done using Energy dispersive X-ray detection. Electrical conductivity under dark and illumination conditions was evaluated. Optical band gap was computed using transmittance and reflectance spectra. The band gap value was in the range 1.8-2.6 eV corresponding to a direct allowed transition. We studied the effect of indium layer thickness and selenium deposition time on the structure, electrical and optical properties of In{sub 6}Se{sub 7} thin films.

  17. Effect of deposition distance on thickness and microstructure of silicon thin film produced by electron beam evaporation; Efeito da distancia de deposicao na espessura e microestrutura de filme fino obtido por evaporacao por feixe de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Toledo, T.F.; Ramanery, F.P.; Branco, J.R.T. [Fundacao Centro Tecnologico de Minas Gerais, Belo Horizonte, MG (Brazil)], e-mail: thalitaqui@yahoo.com.br; Cunha, M.A. [Acos Especiais Itabira S.A. (Acesita), Belo Horizonte, MG (Brazil)

    2006-07-01

    The interest for materials with new characteristics and properties made thin films an area of highest research interest. Silicon thin films have been widely used in solar cells, being the main active layer. In this work, the effect of deposition distance on thickness and microstructure of silicon films was investigated. The electron beam evaporation technique with argon plasma assistance was used to obtain films on stainless steel 304, Fe-Si alloy and soda lime glass. The experiments were made varying electron beam current and deposition pressure. The results are discussed based on Hertz-Knudsen's law and thin films microstructure evolution models. The samples were characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction and profilometer. (author)

  18. Full-Scale Testing Technology Maturation Of A Thin Film Evaporator For High-Level Liquid Waste Management At Hanford - 12125

    International Nuclear Information System (INIS)

    Simulant testing of a full-scale thin-film evaporator system was conducted in 2011 for technology development at the Hanford tank farms. Test results met objectives of water removal rate, effluent quality, and operational evaluation. Dilute tank waste simulant, representing a typical double-shell tank supernatant liquid layer, was concentrated from a 1.1 specific gravity to approximately 1.5 using a 4.6 m2 (50 ft2) heated transfer area Rototherm(regsign) evaporator from Artisan Industries. The condensed evaporator vapor stream was collected and sampled validating efficient separation of the water. An overall decontamination factor of 1.2E+06 was achieved demonstrating excellent retention of key radioactive species within the concentrated liquid stream. The evaporator system was supported by a modular steam supply, chiller, and control computer systems which would be typically implemented at the tank farms. Operation of these support systems demonstrated successful integration while identifying areas for efficiency improvement. Overall testing effort increased the maturation of this technology to support final deployment design and continued project implementation.

  19. Structure and superconducting properties of YBa2Cu3O7-x films prepared by nitrogen laser evaporation and CO2 laser annealing in oxygen

    International Nuclear Information System (INIS)

    Superconducting YBa2Cu3O7-x thin films were obtained under high vacuum (10-5 Torr) on substrates of polycrystalline Al2O3 sapphire, SrTiO3, and Si, having zero resistance at 81, 85, 87, and 79 K, respectively. A N2 laser of 3.5 J cm-2 energy density was used for the evaporation. The substrates were heated by a cw single-mode CO2 laser and the annealing was performed by the same laser in O2 atmosphere. Local planar superconducting regions were obtained by focusing the radiation of the cw CO2 laser upon the films. The films were investigated by scanning electron microscope, x-ray microanalysis, and x-ray diffraction

  20. Characterization of thin films of a-SiOx (1.1evaporation of SiO

    International Nuclear Information System (INIS)

    Thin films of a-SiOx with values of x ranging from 1.13 to 1.89 were prepared by reactive evaporation of SiO in a controlled oxygen environment. The oxygen pressure in the deposition chamber was varied so as to obtain films with different values of x. The films were studied by x-ray photoelectron spectroscopy and optical spectrophotometry. An attempt was made to analyse the Si 2p core-level spectra in terms of five chemically shifted components corresponding to basic Si bonding units Si-(Si4-nOn) with n 0,1,...,4. The concentration of these bonding units as a function of oxygen concentration was in reasonable agreement with the random-bonding model, with the exception that the Si-(Si3O) component was almost completely suppressed for all stoichiometries. Films with x2) as the values of x increase. For the films with the largest value of x (= 1.89), the refractive index is smaller than that of fused silica. The density of these films was estimated to be smaller than that of fused silica by about 13%

  1. Influences of oxygen partial pressure on structure and related properties of ZrO2 thin films prepared by electron beam evaporation deposition

    International Nuclear Information System (INIS)

    ZrO2 thin films were prepared by electron beam evaporation at different oxygen partial pressures. The influences of oxygen partial pressure on structure and related properties of ZrO2 thin films were studied. Transmittance, thermal absorption, structure and residual stress of ZrO2 thin films were measured by spectrophotometer, surface thermal lensing technique (STL), X-ray diffraction and optical interferometer, respectively. The results showed that the structure and related properties varied progressively with the increase of oxygen partial pressure. The refractive indices and the packing densities of the thin films decreased when the oxygen partial pressure increased. The tetragonal phase fraction in the thin films decreased gradually as oxygen partial pressure increased. The residual stress of film deposited at base pressure was high compressive stress, the value decreased with the increase of oxygen partial pressure, and the residual stress became tensile with the further increase of oxygen pressure, which was corresponding to the evolution of packing densities and variation of interplanar distances

  2. Influence of substrate temperature on structural, electrical and optical properties of flash evaporated CuIn0.60Al0.40Se2 thin films

    International Nuclear Information System (INIS)

    CuIn0.60Al0.40Se2 thin films were grown by the flash evaporation method onto glass substrates held at temperatures in the range 303-623 K. The influence of substrate temperature on growth of the films was studied. The growth of the highly (111) oriented CuIn0.60Al0.40Se2 thin films was observed at TS=598 K exhibiting sphalerite structure. The surface morphology of CuIn0.60Al0.40Se2 films deposited at TS=623 K indicates segregation of Cu2-xSe binary phase. The electrical resistivity was around 66 Ωcm (300 nm) with p-type conductivity for the films deposited at 598 K. The temperature dependence of the electrical conductivity suggested that above 493 K the conduction mechanism was intrinsic, whereas extrinsic/impurity conduction dominated in the range 303-473 K. The single phase CuIn0.60Al0.40Se2 films showed an optical bandgap of 1.37 eV. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Formation of CuO on thermal and laser-induced oxidation of Cu3N thin films prepared by modified activated reactive evaporation

    Science.gov (United States)

    Sahoo, Guruprasad; Jain, Mahaveer K.

    2015-03-01

    Copper oxide (CuO) thin films were prepared by direct oxidation of modified activated reactive evaporated copper nitride (Cu3N) thin films in air ambience. When annealed in air at higher temperatures, Cu3N films undergo complete decomposition and the residual Cu gets easily bonded with the atmospheric oxygen to form CuO. Annealing provides required activation energy for the formation of CuO. The formation of fairly crystallized CuO was confirmed by X-ray diffraction and Raman spectroscopy studies. However, the crystallite size of CuO films is smaller than their corresponding Cu3N phase. The surface morphology of the CuO films obtained through this method shows grains of non-uniform size distribution. Furthermore, Raman spectra on the as-grown Cu3N films were taken by varying the laser power. At higher laser power, microscopic CuO dots are formed due to laser-induced oxidation. It is proposed that p-type CuO can be easily grown over suitably prepared n-type Cu3N by local heating or laser irradiation in air.

  4. 伞板型布膜器对降膜蒸发性能的影响%UMBRELLA DISTRIBUTOR IN FALLING FILM EVAPORATOR

    Institute of Scientific and Technical Information of China (English)

    李瑞; 董伟志; 史晓平; 张少峰

    2000-01-01

    Falling film evaporator(FFE)is a kind of effective,energy-saving evaporating equipment,while the calculation of the heat transfer coefficient is not as accurate as is expected,which is partially due to neglecting the impact of distributor on heat transfer in FFE.For this purpose,a coefficient named Distributor Influence Coefficient is introduced which enable us to get the heat transfer coefficient form a new point of view.It is carried out with a new-type distributor--Umbrella Distributor,and furthermore,the influence of various factors is analyzed,which provides new thoughts for the calculation of heat transfer coefficient in the practical design.

  5. High carrier mobility of CoPc wires based field-effect transistors using bi-layer gate dielectric

    Directory of Open Access Journals (Sweden)

    Murali Gedda

    2013-11-01

    Full Text Available Polyvinyl alcohol (PVA and anodized Al2O3 layers were used as bi-layer gate for the fabrication of cobalt phthalocyanine (CoPc wire base field-effect transistors (OFETs. CoPc wires were grown on SiO2 surfaces by organic vapor phase deposition method. These devices exhibit a field-effect carrier mobility (μEF value of 1.11 cm2/Vs. The high carrier mobility for CoPc molecules is attributed to the better capacitive coupling between the channel of CoPc wires and the gate through organic-inorganic dielectric layer. Our measurements also demonstrated the way to determine the thicknesses of the dielectric layers for a better process condition of OFETs.

  6. High carrier mobility of CoPc wires based field-effect transistors using bi-layer gate dielectric

    International Nuclear Information System (INIS)

    Polyvinyl alcohol (PVA) and anodized Al2O3 layers were used as bi-layer gate for the fabrication of cobalt phthalocyanine (CoPc) wire base field-effect transistors (OFETs). CoPc wires were grown on SiO2 surfaces by organic vapor phase deposition method. These devices exhibit a field-effect carrier mobility (μEF) value of 1.11 cm2/Vs. The high carrier mobility for CoPc molecules is attributed to the better capacitive coupling between the channel of CoPc wires and the gate through organic-inorganic dielectric layer. Our measurements also demonstrated the way to determine the thicknesses of the dielectric layers for a better process condition of OFETs

  7. High carrier mobility of CoPc wires based field-effect transistors using bi-layer gate dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Gedda, Murali; Obaidulla, Sk. Md. [Department of Physics, Indian Institute of Technology Guwahati, Guwahati-781039 (India); Subbarao, Nimmakayala V. V. [Centre for Nano Technology, Indian Institute of Technology Guwahati, Guwahati-781039 (India); Goswami, Dipak K. [Department of Physics, Indian Institute of Technology Guwahati, Guwahati-781039 (India); Centre for Nano Technology, Indian Institute of Technology Guwahati, Guwahati-781039 (India)

    2013-11-15

    Polyvinyl alcohol (PVA) and anodized Al{sub 2}O{sub 3} layers were used as bi-layer gate for the fabrication of cobalt phthalocyanine (CoPc) wire base field-effect transistors (OFETs). CoPc wires were grown on SiO{sub 2} surfaces by organic vapor phase deposition method. These devices exhibit a field-effect carrier mobility (μ{sub EF}) value of 1.11 cm{sup 2}/Vs. The high carrier mobility for CoPc molecules is attributed to the better capacitive coupling between the channel of CoPc wires and the gate through organic-inorganic dielectric layer. Our measurements also demonstrated the way to determine the thicknesses of the dielectric layers for a better process condition of OFETs.

  8. Nanopatterning using a simple bi-layer lift-off process for the fabrication of a photonic crystal nanostructure

    International Nuclear Information System (INIS)

    A simple and versatile method for fabricating nanopatterns by a lift-off procedure is demonstrated. The technique involves the use of molecular transfer lithography based on water-soluble templates to form a nanopatterned UV-curable material on a PMGI layer, which serves as an underlying resin suitable for lift-off processes. This bi-layer procedure is used for the fabrication of nickel patterns, which are subsequently used as a hard mask for plasma etch processing. Using this procedure, a two-dimensional TiO2 photonic crystal layer with a 450 nm lattice constant is fabricated on Y3Al5O12:Ce3+ (YAG:Ce) yellow ceramic plate phosphor to enhance its forward emission. The yellow emission in the forward direction is improved by a factor of 3.5 compared to that of a conventional non-scattering YAG:Ce phosphor plate excited by a blue LED. (paper)

  9. Magnetoelectric properties of particulate and bi-layer PMN-PT/CoFe{sub 2}O{sub 4} composites

    Energy Technology Data Exchange (ETDEWEB)

    Mathe, V.L., E-mail: vlmathe@physics.unipune.ernet.in [Novel Materials Research Laboratory, Department of Physics, University of Pune, Pune, 411 007 Maharastra (India); Sheikh, A.D. [Novel Materials Research Laboratory, Department of Physics, University of Pune, Pune, 411 007 Maharastra (India); Srinivasan, G. [Physics Department, Oakland University, Rochester, MI 48309 (United States)

    2012-03-15

    Our studies comprise electrical dielectric and magnetoelectric properties of CoFe{sub 2}O{sub 4} (CFO) and Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.67}Ti{sub 0.33}O{sub 3} [PMN-PT] magnetoelectric composites. The individual phases were prepared by conventional ceramic method. The particulate composites of ferrite and ferroelectric phases were prepared in ferroelectric rich region. Presence of both the phases in the composites was confirmed using X-ray diffraction techniques. The scanning electron microscopic images recorded in backscattered mode were used to study the microstructure of composites. Lattice constant, dielectric constant, electrical resistivity, ferroelectric, and magnetic properties of individual as well as particulate composites were studied. Further the bi-layer composites were made using the discs obtained from the powders of individual phases where hot press technique was employed to obtain disc of individual phases. CFO phase used in bi-layer composites was obtained using chemical co-precipitation technique. Magnetoelectric (ME) measurements were carried out on both, particulate and layered magnetoelectric composites. Comparison of ME signal obtained from particulate and layered composites revealed that the layered composites gives superior magnetoelectric signal. ME data obtained for layered composites show good agreement with the theoretical model. - Highlights: Black-Right-Pointing-Pointer Study on dielectric, electrical, ferroelectric, and magnetic properties of particulate magnetoelectric composite of PMN-PT/CFO. Black-Right-Pointing-Pointer These properties are correlated with the magnetoelectric effect in particulate composites. Black-Right-Pointing-Pointer Magnetoelectric properties of particulate composites are compared with bilayer magnetoelectric composites of PMN-PT/CFO. Black-Right-Pointing-Pointer Magnetoelectric signal obtain for bilayer composites show good agreement with theoretical model suggested by Bichurin et al.

  10. Structure, microstructure and magnetic properties of Ni{sub 75}Fe{sub 25} films elaborated by evaporation from nanostructured powder

    Energy Technology Data Exchange (ETDEWEB)

    Kaibi, A., E-mail: kaibi_amel@yahoo.fr [Laboratory of Materials Physics (LPM), Faculty of Physics, USTHB, BP 32 El Alia, Algiers (Algeria); Guittoum, A. [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399, Algiers (Algeria); Öksüzoğlu, R.M.; Yağci, A.M. [University of Anadolu, Faculty of Engineering, Department of Materials Sciences and Engineering, İkiEylül Campus, 26555 Eskişehir (Turkey); Boudissa, M. [ENMC Laboratory, Physics Department, University of Sétif, 19000 (Algeria); Kechouane, M. [Laboratory of Materials Physics (LPM), Faculty of Physics, USTHB, BP 32 El Alia, Algiers (Algeria)

    2015-09-30

    Highlights: • Ni{sub 75}Fe{sub 25} permalloy (Py) thin films with different thicknesses were deposited by vacuum evaporation from nanocrystalline powder onto Si(1 1 1) substrate. • The texture was found to change with increasing thickness. • The existence of nanosized grains with a uniform distribution has been observed. • The existence of a uniaxial magnetic anisotropy with an easy axis parallel to the film plane has been evidenced. • The coercive field was found to decrease with increasing thickness. - Abstract: We report on the structural, microstructural and magnetic properties of Ni{sub 75}Fe{sub 25} permalloy (Py) thin films. Py thin films with different thicknesses were deposited by vacuum evaporation from nanocrystalline powder onto Si (11) substrate. The thickness varies from 16 nm to 250 nm. From grazing X-ray diffraction patterns (GIXRD), we have shown the presence of a strong 〈200〉 texture for the lowest thickness (16 nm). For the 52 nm and 84 nm thick samples, a strong 〈111〉 preferred orientation is developed. However, for higher thicknesses, a polycrystalline structure is present. From the Scanning Electron Microscopy observations (SEM), we have shown that the surface seems to be very dense with many fine grains. The analysis of EDX spectra revealed that the sample composition is close to the starting Ni{sub 75}Fe{sub 25} powder. A more accurate investigation of the morphology was performed with the atomic force microscopy (AFM). We have shown the existence of nanosized grains with a uniform distribution. The mean diameter of the grains increases from 27 nm to 40 nm when the thickness increases. From magnetic measurements, we have shown the existence of a uniaxial magnetic anisotropy with an easy axis parallel to the film plane. The coercive field, H{sub C} was found to decrease with increasing thickness.

  11. Design of Thermopile-Based Infrared Detectors with Suspended Absorber-Thermopile Bi-Layers%一种基于悬浮吸收层的双层结构的热电堆红外探测器

    Institute of Scientific and Technical Information of China (English)

    陈媛婧; 毛海央; 谭秋林; 薛晨阳; 欧文; 陈大鹏; 熊继军

    2014-01-01

    A novel infrared ( IR ) detector is designed and presented. The detector takes advantage of suspended absorber-thermopile bi-layers to achieve high performance with a relatively small size. The bi-layers are realized by using two separated sacrificial layers, which include a Poly-Si film beneath the thermopiles and a polyimide deposition over the thermopiles. Simulation results demonstrate that the detectivity,responsibility and response time of the IR detectors can reach 2. 85×108 cmHz(1/2)/W,1 800 V/W and 6 ms,respectively. Moreover,the fabrication of the IR detector is highly compatible with standard CMOS process, which as a result, makes the high-yield and low-cost production possible.%提出一种新颖红外传感器,这种传感器采用悬浮吸收层的双层结构的优势,来实现相对小尺寸下的高探测性能。双层结构采用2种牺牲层材料,分别为聚酰亚胺牺牲层和预埋在热偶条和沉底之间的多晶硅材料。仿真结果证明了该种结构的探测率、响应率和响应时间分别达到2.85×108 cm Hz(1/2)/W、1800 V/W和6 ms。本文给出了该种热电堆红外探测器高度兼容于CMOS工艺的制备流程,使器件的高效量产和低成本生产成为可能。

  12. Characterization of thin films of a-SiO{sub x} (1.1evaporation of SiO

    Energy Technology Data Exchange (ETDEWEB)

    Durrani, S M A [Centre for Applied Physical Sciences, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Kuhaili, M F [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Khawaja, E E [Centre for Applied Physical Sciences, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2003-12-03

    Thin films of a-SiO{sub x} with values of x ranging from 1.13 to 1.89 were prepared by reactive evaporation of SiO in a controlled oxygen environment. The oxygen pressure in the deposition chamber was varied so as to obtain films with different values of x. The films were studied by x-ray photoelectron spectroscopy and optical spectrophotometry. An attempt was made to analyse the Si 2p core-level spectra in terms of five chemically shifted components corresponding to basic Si bonding units Si-(Si{sub 4-n}O{sub n}) with n 0,1,...,4. The concentration of these bonding units as a function of oxygen concentration was in reasonable agreement with the random-bonding model, with the exception that the Si-(Si{sub 3}O) component was almost completely suppressed for all stoichiometries. Films with x<1.65 consisted of elemental Si and oxides of silicon, while those with x {>=} 1.65 were almost free of Si. Films containing Si have higher refractive indices and degrees of absorption in the visible region compared with those which were free of Si. The optical properties of the films approach those of fused silica (SiO{sub 2}) as the values of x increase. For the films with the largest value of x (= 1.89), the refractive index is smaller than that of fused silica. The density of these films was estimated to be smaller than that of fused silica by about 13%.

  13. The influence of substrate temperature on the morphology, optical and electrical properties of thermal-evaporated ZnTe Thin Films

    International Nuclear Information System (INIS)

    The structural, morphological, optical and electrical properties of ZnTe films deposited by evaporation were investigated as a function of substrate temperature (at -123 and 27 deg. C) and post-deposition annealing temperature (at 200, 300 and 400 deg. C). It was determined that films deposited at both substrate temperatures were polycrystalline in nature with zinc-blende structure and a strong (1 1 1) texture. A small Te peak was detected in XRD spectra for both substrate temperatures, indicating that as-deposited ZnTe films were slightly rich in Te. Larger grains and a tighter grain size distribution were obtained with increased substrate temperature. Scanning electron microscopy (SEM) studies showed that the microstructures of the as-deposited films agreed well with the expectations from structure zone model. Post-deposition annealing induced further grain growth and tightened the grain size distribution. Annealing at 400 deg. C resulted in randomization in the texture of films deposited at both substrate temperatures. Optical spectroscopy results of the films indicated that the optical band gap value increased from 2.13 to 2.16 eV with increased substrate temperature. Increasing the annealing temperature sharpened the band-edge. Resistivity measurements showed that the resistivity of films deposited at substrate temperatures of -123 and 27 deg. C were 32 Ω cm, and 1.0 x 104 Ω cm, respectively with corresponding carrier concentrations of 8.9 x 1015 cm-3 and 1.5 x 1014 cm-3. Annealing caused opposite changes in the film resistivity between the samples prepared at substrate temperatures of -123 and 27 deg. C.

  14. Eects of Post Deposition Treatments on Vacuum Evaporated CdTe Thin Films and CdS=CdTe Heterojunction Devices

    OpenAIRE

    BAYHAN, Habibe; ERÇELEBİ, Çiğdem

    1998-01-01

    CdTe, CdS thin films and n-CdS/p-CdTe heterostructures have been prepared by conventional vacuum evaporation technique. Some post deposition treatments to optimize the device efficiency have been analyzed and the effects of the individual process steps on the material and device properties were investigated. Annealing in air with and without CdCl2-treatment decreased the CdTe resistivity. The CdCl2-dip followed by annealing in air at 300\\circC for 5 min improved the grain size and polycrystal...

  15. Effects of sulfurization temperature on Cu2ZnSnS4 thin film deposited by single source thermal evaporation method

    Science.gov (United States)

    Zakaria, Zaihasraf; Chelvanathan, Puvaneswaran; Junaebur Rashid, Mohammad; Akhtaruzzaman, Md; Mezbaul Alam, Mohammad; Abdullah Al-Othman, Zeid; Alamoud, Abdulrahman; Sopian, Kamaruzzaman; Amin, Nowshad

    2015-08-01

    In this study, the effects of sulfurization temperature on the properties of thermally evaporated Cu2ZnSnS4 (CZTS) thin films were investigated. Molybdenum (Mo) coated soda lime glass (SLG) was used as substrates and stoichiometric CZTS powder (99.95%) was used as the source material. XRD patterns showed that CZTS were formed with preferential orientations of (112) > (220) > (312) for all the investigated films. The intensity of (112) peak is found increasing until a certain temperature indicating that the highest degree of crystallinity is achieved together with secondary phases such as ZnS and SnS. It was confirmed by raman shift at 338 cm-1 from Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM) results showed a trend for surface roughness as well as morphology. From Hall effect measurement, all deposited films exhibited p-type conductivity. From UV-vis spectroscopy measurement, the optical band gap of all the films are found in the range of potential absorbers for CZTS based thin film solar cells.

  16. Nonlinear optical studies on 4-(ferrocenylmethylimino)-2-hydroxy-benzoic acid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

    Science.gov (United States)

    Matei, Andreea; Marinescu, Maria; Constantinescu, Catalin; Ion, Valentin; Mitu, Bogdana; Ionita, Iulian; Dinescu, Maria; Emandi, Ana

    2016-06-01

    We present results on a new, laboratory synthesized ferrocene-derivative, i.e. 4-(ferrocenylmethylimino)-2-hydroxy-benzoic acid. Thin films with controlled thickness are deposited by matrix-assisted pulsed laser evaporation (MAPLE), on quartz and silicon substrates, with the aim of evaluating the nonlinear optical properties for potential optoelectronic applications. Dimethyl sulfoxide was used as matrix, with 1% wt. concentration of the guest compound. The frozen target is irradiated by using a Nd:YAG laser (4ω/266 nm, 7 ns pulse duration, 10 Hz repetition rate), at low fluences ranging from 0.1 to 1 J/cm2. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to probe the surface morphology of the films. Fourier transform infrared (FTIR) and Raman spectroscopy reveal similar structure of the thin film material when compared to the starting material. The optical properties of the thin films are investigated by spectroscopic-ellipsometry (SE), and the refractive index dependence with respect to temperature is studied. The second harmonic generation (SHG) potential is assessed by using a femtosecond Ti:sapphire laser (800 nm, 60-100 fs pulse duration, 80 MHz repetition rate), at 200 mW maximum output power, revealing that the SHG signal intensity is strongly influenced by the films' thickness.

  17. Laser-induced damage threshold of ZrO2 thin films prepared at different oxygen partial pressures by electron-beam evaporation

    International Nuclear Information System (INIS)

    ZrO2 films were deposited by electron-beam evaporation with the oxygen partial pressure varying from 3x10-3 Pa to 11x10-3 Pa. The phase structure of the samples was characterized by x-ray diffraction (XRD). The thermal absorption of the films was measured by the surface thermal lensing technique. A spectrophotometer was employed to measure the refractive indices of the samples. The laser-induced damage threshold (LIDT) was assessed using a 1064 nm Nd: yttritium-aluminum-garnet pulsed laser at pulse width of 12 ns. The influence of oxygen partial pressure on the microstructure and LIDT of ZrO2 films was investigated. XRD data revealed that the films changed from polycrystalline to amorphous as the oxygen partial pressure increased. The variation of refractive index at 550 nm wavelength indicated that the packing density of the films decreased gradually with increasing oxygen partial pressure. The absorptance of the samples decreased monotonically from 125.2 to 84.5 ppm with increasing oxygen partial pressure. The damage threshold values increased from 18.5 to 26.7 J/cm2 for oxygen partial pressures varying from 3x10-3 Pa to 9x10-3 Pa, but decreased to 17.3 J/cm2 in the case of 11x10-3 Pa

  18. Evaporation-Driven Deposition of WO3 Thin Films from Organic-Additive-Free Aqueous Solutions by Low-Speed Dip Coating and Their Photoelectrochemical Properties.

    Science.gov (United States)

    Uchiyama, Hiroaki; Igarashi, Seishirou; Kozuka, Hiromitsu

    2016-04-01

    We prepared tungsten trioxide (WO3) photoelectrode films from organic-additive-free aqueous solutions by a low-speed dip-coating technique. The evaporation-driven deposition of the solutes occurred at the meniscus during low-speed dip coating, resulting in the formation of coating layer on the substrate. Homogeneous WO3 precursor films were obtained from (NH4)10W12O41·5H2O aqueous solutions and found to be crystallized to monoclinic WO3 films by the heat treatment at 400-700 °C. All the films showed a photoanodic response irrespective of the heat treatment temperature, where a good photoelectrochemical stability was observed for those heated over 500 °C. The highest photoanodic performance was observed for the WO3 film heated at 700 °C, where the IPCE (incident photon-to-current efficiency) was 36.2% and 4.6% at 300 and 400 nm, respectively. PMID:27010979

  19. Growth and physical properties of p-Zn x Cd1- x S thin films thermally evaporated on ITO-coated glass substrates

    Science.gov (United States)

    Yoon, Eun Jeong; Han, Dong Hun; Lee, Jeoung Ju; Lee, Jong Duk; Kang, Kwang Yong; Lee, Seung Hwan; Shewale, Prashant Shivaji

    2015-01-01

    Zn x Cd1- x S ( x = 0.15, 0.44, 0.62, 0.80, and 0.95) thin films of about 340 nm in thickness were deposited on indium-tin-oxide (ITO)-coated glass substrates by using thermal evaporation of high-purity ZnS and CdS mixed tablets in high vacuum. X-ray diffraction spectra showed that the Zn x Cd1- x S thin films were preferentially grown along the (111) orientation. The Zn x Cd1- x S crystal structure was a mixture structure of the ZnS and the CdS cubic zincblende structures with lattice constants a = 5.670 Å to a = 5.734 Å for CdS and a = 5.437 Å for ZnS. The ( αh ν)2 vs. h ν plots for the Zn x Cd1- x S thin films showed that all samples had direct transition band gaps. The energy band gaps of the Zn x Cd1- x S thin films increased monotonically from 2.45 eV for x = 0.15 to 3.37 eV for x = 0.95. The dynamical behavior of the charge carriers in the Zn x Cd1- x S thin films was investigated by using the photoinduced discharge characteristics (PIDC) technique.

  20. Analysis of Evaporation Heat Transfer of Thin Liquid Film in a Capillary of Equilateral Triangular Cross-Section

    Institute of Scientific and Technical Information of China (English)

    Miao Jianyin; Wang Jinliang; Ma Tongze

    2001-01-01

    In this paper, theoretical analysis on evaporating heat transfer in capillary with equilateral triangular cross section is presented and numerical calculations based on glass-water system are carried out. Considering evaporation mechanism in capillary with polygonal section, one-dimensional model is used to describe the three-dimensional case. The evaporating meniscus in the capillary along axis can be divided into six regions. The following conclusions are obtained: (1) The local heat transfer coefficients and heat fluxes in capillary increase quickly in the first and second regions, and slowly in the third region. The maximum value appears at interline between the third and fourth regions, then gradually decreases in the last three regions. (2) The average heat transfer coefficients decrease when the sizes of the capillary section increase, and become larger under higher wall temperature.

  1. Formation and evolution of the unexpected PbI2 phase at the interface during the growth of evaporated perovskite films.

    Science.gov (United States)

    Xu, Haitao; Wu, Yanglin; Cui, Jian; Ni, Chaowei; Xu, Fuzong; Cai, Jiang; Hong, Feng; Fang, Zebo; Wang, Wenzhen; Zhu, Jiabin; Wang, Linjun; Xu, Run; Xu, Fei

    2016-07-21

    The interface chemistry and evolution of the evaporated perovskite films on ITO, pedot/ITO, Si and glass substrates are studied. As evidenced by X-ray diffraction and X-ray photoemission spectroscopy (XPS) results, the PbI2 phase is found to be inevitably formed at the very initial growth stage, even under the conditions of a MAI-rich environment. The extremely low binding energy of adsorbed MAI particles on all the above substrates, as compared to that of PbI2 particles, is responsible for the presence of the PbI2 phase at the interface. The formation of both hole and electron barriers at the interface of PbI2/MAPbI3, as evidenced by XPS measurements, could block carrier transport into the electrode and thus deteriorate solar cell performance. This result reveals the origin of the poor performance of perovskite solar cells (PSCs) by the vacuum evaporation method, and may help to improve the performance of PSCs made using the vacuum evaporation method. PMID:27346149

  2. Influence of composition on optical and dispersion parameters of thermally evaporated non-crystalline Cd50S50−xSex thin films

    International Nuclear Information System (INIS)

    Non-crystalline thin films of chalcogenide Cd50S50−xSex system (30 ≤ x ≤ 50) were obtained by thermal evaporation technique onto a pre-cleaned glass substrate at a vacuum of 8.2 × 10−4 Pa. The deposition rate and film thickness were kept constant at about 8 nm/s and 200 nm, respectively. Amorphous/crystalline nature and chemical composition of films have been checked using X-ray diffraction and energy dispersive X-ray spectroscopy (EDX). Optical properties of thin films were investigated and studied using the corrected transmittance, T(λ) and corrected reflectance, R(λ) measurements. Obtained data reveal that, the indirect optical energy gap (Eg) was decreased from 2.21 to 1.57 eV. On the contrary, Urbach energy (band tail width), EU was found to be increased from 0.29 to 0.45 eV. This behavior is believed to be associated with the increase of Se-content instead of S-content in the thin films of Cd50S50−xSex system. Chemical bond approach model, CBA was used to analyze the obtained values of Eg and EU. Optical density, skin depth, extinction coefficient, refractive index and optical conductivity of chalcogenide CdSSe thin films were discussed as functions of Se-content. Using Wemple-DiDomenico single oscillator model, the refractive index dispersion and energy parameters and their dependence on Se content were studied. - Highlights: • Amorphous thin films of thickness 200 nm of Cd50S50−xSex (30 ≤ x ≤ 50) have prepared. • Optical properties, indirect optical energy gap and band tail width were studied. • Chemical bond approach, CBA was used to analyze the obtained values of Eg and EU. • New data of dispersion refractive index parameters were investigated and discussed

  3. The optimization functions of ICP discharge in preparation of Cu-Zn-Sn precursors and CZTS films by co-evaporation

    Science.gov (United States)

    Ye, Li; Junfang, Chen; Junhui, Ma; Lifen, Zhou

    2016-02-01

    Cu-Zn-Sn (CZT) precursors were successfully prepared on glass substrate with the introduction of the assistant technology ICP (inductively coupled plasma) based on the conventional co-evaporation process. The deposition was performed with the substrate temperature at 220 °C and the chamber pressure at 6.5 × 10-2 Pa. Argon plasma was investigated with a Langmuir probe. The plasma density and the electron temperature increased with the increasing of the discharge power. The impact of ICP discharge power on the structural and morphological properties of the CZT film were investigated with energy dispersive X-ray spectrometers (EDS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). XRD and EDS were combined to investigate the structure of the film. The results show that Zn loss exists during the evaporation and the loss can be reduced by increasing the ICP discharge power. From the observation on the scanning electron microscope, the grain size becomes larger with argon plasma's assistance. The preparation of the Cu2ZnSnS4 (CZTS) film and the measured properties demonstrate that the ICP would optimize the growth of the film. Project supported by the Natural Science Foundation of Guangdong Province, China (No. S2013010012548), the Natural Science Foundation of Guangdong Province, China (No. 10151063101000048), the Key Program of the National Natural Science Foundation of China (No. 61072028), the Guangdong Provincial Natural Science Foundation of China (No. 2014A030313441), and the Guangdong Province and Chinese Ministry of Education Cooperation Project of Industry, Education and Academy (No. 2013B090600063).

  4. Efficient upconversion polymer-inorganic nanocomposite thin film emitters prepared by the double beam matrix assisted pulsed laser evaporation (DB-MAPLE)

    Science.gov (United States)

    Darwish, Abdalla M.; Burkett, Allan; Blackwell, Ashley; Taylor, Keylantra; Walker, Vernell; Sarkisov, Sergey; Koplitz, Brent

    2014-09-01

    We report on fabrication and investigation of optical and morphological properties of highly efficient (a quantum yield of 1%) upconversion polymer-inorganic nanocomposite thin film emitters prepared by the new technique of double beam matrix assisted pulsed laser evaporation (DB-MAPLE). Polymer poly(methyl methacrylate) (PMMA) host was evaporated on a silicon substrate using a 1064-nm pulsed laser beam using a target made of frozen (to the temperature of liquid nitrogen) solution of PMMA in chlorobenzene. Concurrently, the second 532-nm pulsed beam from the same laser was used to impregnate the polymer host with the inorganic nanoparticulate made of the rare earth upconversion compounds NaYF4: Yb3+, Er3+, NaYF4: Yb3+, Ho3+, and NaYF4: Yb3+, Tm3+. The compounds were initially synthesized using the wet process, baked, and compressed in solid pellet targets. The proposed DB-MAPLE method has the advantage of making highly homogeneous nanocomposite films with precise control of the doping rate due to the optimized overlapping of the plumes produced by the ablation of the organic and inorganic target with the infrared and visible laser beams respectively. X-ray diffraction, electron and atomic force microscopy, and optical fluorescence spectroscopy indicated that the inorganic nanoparticulate preserved its crystalline structure and upconversion properties (strong emission in green, red, and blue bands upon illumination with 980-nm laser diode) after being transferred from the target in the polymer nanocomposite film. The produced films can be used in applications varying from the efficiency enhancement of the photovoltaic cells, optical sensors and biomarkers to anti-counterfeit labels.

  5. ZnO/CdS bi-layer nanostructures photoelectrode for dye-sensitized solar cells

    Science.gov (United States)

    Dalal, Paresh V.; Deshpande, Milind P.; Solanki, Bharat G.; Soni, Saurabh S.

    2016-05-01

    Simple chemical deposition method for the synthesis of ZnO/CdS bilayer photoelectrode on fluorine doped tin oxide (FTO) coated glass substrate in aqueous medium at low temperature (coated glass substrates by dip-coating method, whereas CdS nanorods were successfully synthesized on pre-deposited ZnO film by Chemical Bath Deposition (CBD) method. The Photovoltaic properties of FTO/ZnO/CdS bilayer photo electrodes were also studied. A maximum short circuit current density of 9.1 mA cm-2 and conversion efficiency 1.05% are observed for ZnO/CdS_10min. Layer, which supports fast electron injection kinetics due to hetero structured nanorod, while minimum values of 0.53mA cm-2 and 0.01% respectively are observed for only ZnO deposited layer.

  6. Effect of selenium doping on structural and optical properties of SnS:Se thin films by electron beam evaporation method

    Science.gov (United States)

    Henry, Johnson; Mohanraj, Kannusamy; Kannan, Selvaraj; Barathan, Seshathri; Sivakumar, Ganesan

    2013-01-01

    SnS nanoparticle has been synthesized initially using SnCl2 · 2H2O and Na2S · XH2O, in the presence of TEA by precipitation method and XRD and FTIR techniques have been used for characterization of the sample. Powder X-ray diffraction studies revealed the particle size to be 48 nm and the pattern represents polycrystalline herzenbergite orthorhombic crystal structure of SnS. The FTIR result also confirmed the SnS at 2354 cm-1. Secondly SnS:Se thin films have been deposited on glass substrates by electron beam evaporation technique and the films were annealed at 100 °C and 200 °C for 1 h. The unannealed films are amorphous in nature and the annealed film shows that a sharp crystalline peak is due to SnS. Also a peak is shown at 2θ = 14.39°, which is due to characteristic peak of SnSe2, established by their XRD patterns. The band gap energy (Eg) was determined from transmission spectra and an optical band gap of Eg varies from 1.6 eV to 1.79 eV.

  7. Josephson coupling between superconducting islands on single- and bi-layer graphene

    Science.gov (United States)

    Mancarella, Francesco; Fransson, Jonas; Balatsky, Alexander

    2016-05-01

    We study the Josephson coupling of superconducting (SC) islands through the surface of single-layer graphene (SLG) and bilayer graphene (BLG) in the long-junction regime, as a function of the distance between the grains, temperature, chemical potential and external (transverse) gate-voltage. For SLG, we provide a comparison with existing literature. The proximity effect is analyzed through a Matsubara Green’s function approach. This represents the first step in a discussion of the conditions for the onset of a granular superconductivity within the film, made possible by Josephson currents flowing between superconductors. To ensure phase coherence over the 2D sample, a random spatial distribution can be assumed for the SC islands on the SLG sheet (or intercalating the BLG sheets). The tunable gate-voltage-induced band gap of BLG affects the asymptotic decay of the Josephson coupling-distance characteristic for each pair of SC islands in the sample, which results in a qualitatively strong field dependence of the relation between Berezinskii–Kosterlitz–Thouless transition critical temperature and gate voltage.

  8. Ultra thin films of gadolinium deposited by evaporation in ultra high vacuum conditions: Composition, growth and morphology

    International Nuclear Information System (INIS)

    Ultra-thin gadolinium films with thicknesses between 8 and 101 A were deposited on AT-cut crystalline quartz substrates under ultra high vacuum conditions, and subsequently subjected to composition and morphologic characterization through X-ray photo-spectroscopy analysis and atomic force microscopy. Oxygen contamination is found on the samples, and its amount is estimated in terms of the thickness of an oxygen layer over the gadolinium films after subtracting the contribution to the XPS spectra of the underlying background. Atomic force microscope pictures provide evidence of having metal island films, with two growing regimes: the Volmer-Weber mode for the thinner films considered and the Stranski-Krastanov growing mode for the thicker ones. From evaluation of the sticking coefficient, the shape of the islands is approximated in terms of oblate spheroid caps and variation of the contact angle with film mass thickness is reported.

  9. Ultra thin films of gadolinium deposited by evaporation in ultra high vacuum conditions: Composition, growth and morphology

    Energy Technology Data Exchange (ETDEWEB)

    Herrera-Sancho, O.A.; Castro-Gonzalez, D.; Araya-Pochet, J.A. [Centro de Investigacion en Ciencia e Ingenieria de Materiales, Universidad de Costa Rica, 2060 San Pedro, San Jose (Costa Rica); Escuela de Fisica, Universidad de Costa Rica, 2060 San Pedro, San Jose (Costa Rica); Vargas-Castro, W.E., E-mail: william.vargascastro@ucr.ac.cr [Centro de Investigacion en Ciencia e Ingenieria de Materiales, Universidad de Costa Rica, 2060 San Pedro, San Jose (Costa Rica); Escuela de Fisica, Universidad de Costa Rica, 2060 San Pedro, San Jose (Costa Rica)

    2011-02-01

    Ultra-thin gadolinium films with thicknesses between 8 and 101 A were deposited on AT-cut crystalline quartz substrates under ultra high vacuum conditions, and subsequently subjected to composition and morphologic characterization through X-ray photo-spectroscopy analysis and atomic force microscopy. Oxygen contamination is found on the samples, and its amount is estimated in terms of the thickness of an oxygen layer over the gadolinium films after subtracting the contribution to the XPS spectra of the underlying background. Atomic force microscope pictures provide evidence of having metal island films, with two growing regimes: the Volmer-Weber mode for the thinner films considered and the Stranski-Krastanov growing mode for the thicker ones. From evaluation of the sticking coefficient, the shape of the islands is approximated in terms of oblate spheroid caps and variation of the contact angle with film mass thickness is reported.

  10. Coupling effect between film boiling heat transfer and evaporation drag around a hot-particle in cold liquid

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Yan; YANG Yan-Hua; XU Ji-Jun

    2003-01-01

    Extremely rapid evaporation could occur when high-temperature particles contact withlow-temperature liquid. This kind of phenomenon is associated with the engineering safety and the problems inhigh-transient multi-phase fluid and heat transfer. The aim of our study was to design and build an observable ex-periment facility. The first series of experiments were performed by pouring one or six high-temperature particles intoa low saturated temperature liquid pool. The particle's falling-down speed was recorded by a high-speed camera, thuswe can find the special resistant feature of the moving high-temperature particles, which is induced by the high-speedevaporation surrounding the particles. The study has experimentally verified the theory of evaporation drag model.

  11. Formaldehyde assay by capacitance versus voltage and impedance measurements using bi-layer bio-recognition membrane.

    Science.gov (United States)

    Ben Ali, M; Korpan, Y; Gonchar, M; El'skaya, A; Maaref, M A; Jaffrezic-Renault, N; Martelet, C

    2006-12-15

    A novel formaldehyde sensitive biosensor based on bacterial formaldehyde dehydrogenase (FDH) as a bio-recognition element has been developed. The bio-recognition membrane had bi-layer architecture and consisted of FDH, cross-linked with albumin, and of the cofactor NAD at a high concentration level (first layer). The second layer was a negatively charged Nafion membrane, which prevented a leakage of negatively charged NAD molecules from the bio-membrane. As transducers, gold electrodes SiO(2)/Si/SiO(2)/Ti/Au and electrolyte-insulator-semiconductor Si/SiO(2) (EIS) structures have been used. Changes in capacitance and impedance properties of the bio-recognition membrane have been used for monitoring formaldehyde concentration in a bulk solution. It has been shown that formaldehyde can be detected within a concentration range from 1 microM to 20mM depending on the type of transduction used, with a detection limit of 1 and 100 microM for gold-based and EIS-based transducers, respectively. PMID:16516460

  12. Metglas–Elgiloy bi-layer, stent cell resonators for wireless monitoring of viscosity and mass loading

    International Nuclear Information System (INIS)

    This paper presents the design and evaluation of magnetoelastic sensors intended for wireless monitoring of tissue accumulation in peripheral artery stents. The sensors are fabricated from 28 µm thick foils of magnetoelastic 2826MB Metglas™, an amorphous Ni–Fe alloy. The sensor layer consists of a frame and an active resonator portion. The frame consists of 150 µm wide struts that are patterned in the same wishbone array pattern as a 12 mm × 1.46 mm Elgiloy stent cell. The active portion is a 10 mm long symmetric leaf shape and is anchored to the frame at mid length. The active portion nests within the stent cell, with a uniform gap separating the two. A gold-indium eutectic bonding process is used to bond Metglas™ and Elgiloy foils, which are subsequently patterned to form bi-layer resonators. The response of the sensor to viscosity changes and mass loading that precede and accompany artery occlusion is tested in vitro. The typical sensitivity to viscosity of the fundamental, longitudinal resonant frequency at 361 kHz is 427 ppm cP−1 over a 1.1–8.6 cP range. The sensitivity to mass loading is typically between 63000 and 65000 ppm mg−1 with the resonant frequency showing a reduction of 8.1% for an applied mass that is 15% of the unloaded mass of the sensor. This is in good agreement with the theoretical response. (paper)

  13. Metglas-Elgiloy bi-layer, stent cell resonators for wireless monitoring of viscosity and mass loading

    KAUST Repository

    Viswanath, Anupam

    2012-12-21

    This paper presents the design and evaluation of magnetoelastic sensors intended for wireless monitoring of tissue accumulation in peripheral artery stents. The sensors are fabricated from 28 μm thick foils of magnetoelastic 2826MB Metglas™, an amorphous Ni-Fe alloy. The sensor layer consists of a frame and an active resonator portion. The frame consists of 150 μm wide struts that are patterned in the same wishbone array pattern as a 12 mm × 1.46 mm Elgiloy stent cell. The active portion is a 10 mm long symmetric leaf shape and is anchored to the frame at mid length. The active portion nests within the stent cell, with a uniform gap separating the two. A gold-indium eutectic bonding process is used to bond Metglas™ and Elgiloy foils, which are subsequently patterned to form bi-layer resonators. The response of the sensor to viscosity changes and mass loading that precede and accompany artery occlusion is tested in vitro. The typical sensitivity to viscosity of the fundamental, longitudinal resonant frequency at 361 kHz is 427 ppm cP -1 over a 1.1-8.6 cP range. The sensitivity to mass loading is typically between 63000 and 65000 ppm mg-1 with the resonant frequency showing a reduction of 8.1% for an applied mass that is 15% of the unloaded mass of the sensor. This is in good agreement with the theoretical response. © 2013 IOP Publishing Ltd.

  14. Modeling a dynamic bi-layer contact network of injection drug users and the spread of blood-borne infections.

    Science.gov (United States)

    Fu, Rui; Gutfraind, Alexander; Brandeau, Margaret L

    2016-03-01

    Injection drug users (IDUs) are at high risk of acquiring and spreading various blood-borne infections including human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV) and a number of sexually transmitted infections. These infections can spread among IDUs via risky sexual and needle-sharing contacts. To accurately model the spread of such contagions among IDUs, we build a bi-layer network that captures both types of risky contacts. We present methodology for inferring important model parameters, such as those governing network structure and dynamics, from readily available data sources (e.g., epidemiological surveys). Such a model can be used to evaluate the efficacy of various programs that aim to combat drug addiction and contain blood-borne diseases among IDUs. The model is especially useful for evaluating interventions that exploit the structure of the contact network. To illustrate, we instantiate a network model with data collected by a needle and syringe program in Chicago. We model sexual and needle-sharing contacts and the consequent spread of HIV and HCV. We use the model to evaluate the potential effects of a peer education (PE) program under different targeting strategies. We show that a targeted PE program would avert significantly more HIV and HCV infections than an untargeted program, highlighting the importance of reaching individuals who are centrally located in contact networks when instituting prevention programs. PMID:26775738

  15. 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.

  16. Thin Film Deposition of Conducting Polymers and Carbon Allotropes via Interfacial Solution Processing and Evaporative Vapor Phase Polymerization

    OpenAIRE

    D'Arcy, Julio Marcelo

    2012-01-01

    A new solution processing technique is developed for depositing continuously conductive transparent thin films comprised of conducting polymer nanostructures. The deposition mechanism is driven by interfacial surface tension gradients leading to rapid directional fluid flow known as the Marangoni effect. This technique is a universal solution to thin film deposition for coating any type of substrate at ambient conditions within seconds. The versatility of this method of deposition is further ...

  17. How do evaporating thin films evolve? Unravelling phase-separation mechanisms during solvent-based fabrication of polymer blends

    KAUST Repository

    Wodo, Olga

    2014-10-13

    © 2014 AIP Publishing LLC. Solvent-based fabrication is a flexible and affordable approach to manufacture polymer thin films. The properties of products made from such films can be tailored by the internal organization (morphology) of the films. However, a precise knowledge of morphology evolution leading to the final film structure remains elusive, thus limiting morphology control to a trial and error approach. In particular, understanding when and where phases are formed, and how they evolve would provide rational guidelines for more rigorous control. Here, we identify four modes of phase formation and subsequent propagation within the thinning film during solvent-based fabrication. We unravel the origin and propagation characteristics of each of these modes. Finally, we construct a mode diagram that maps processing conditions with individual modes. The idea introduced here enables choosing processing conditions to tailor film morphology characteristics and paves the ground for a deeper understanding of morphology control with the ultimate goal of precise, yet affordable, morphology manipulation for a large spectrum of applications.

  18. Formulation and In Vitro and In Vivo Evaluation of Lipid-Based Terbutaline Sulphate Bi-layer Tablets for Once-Daily Administration.

    Science.gov (United States)

    Hashem, Fahima M; Nasr, Mohamed; Fathy, Gihan; Ismail, Aliaa

    2016-06-01

    The objective of this study was to prepare and evaluate terbutaline sulphate (TBS) bi-layer tablets for once-daily administration. The bi-layer tablets consisted of an immediate-release layer and a sustained-release layer containing 5 and 10 mg TBS, respectively. The sustained-release layer was developed by using Compritol®888 ATO, Precirol® ATO 5, stearic acid, and tristearin, separately, as slowly eroding lipid matrices. A full 4 × 2(2) factorial design was employed for optimization of the sustained-release layer and to explore the effect of lipid type (X 1), drug-lipid ratio (X 2), and filler type (X 3) on the percentage drug released at 8, 12, and 24 h (Y 1, Y 2, and Y 3) as dependent variables. Sixteen TBS sustained-release matrices (F1-F16) were prepared by melt solid dispersion method. None of the prepared matrices achieved the targeted release profile. However, F2 that showed a relatively promising drug release was subjected to trial and error optimization for the filler composition to develop two optimized matrices (F17 and F18). F18 which consisted of drug-Compritol®888 ATO at ratio (1:6 w/w) and Avicel PH 101/dibasic calcium phosphate mixture of 2:1 (w/w) was selected as sustained-release layer. TBS bi-layer tablets were evaluated for their physical properties, in vitro drug release, effect of storage on drug content, and in vivo performance in rabbits. The bi-layer tablets showed acceptable physical properties and release characteristics. In vivo absorption in rabbits revealed initial high TBS plasma levels followed by sustained levels over 24 h compared to immediate-release tablets. PMID:26335420

  19. Properties of double-layered Ga-doped Al-zinc-oxide/titanium-doped indium-tin-oxide thin films prepared by dc magnetron sputtering applied for Si-based thin film solar cells

    International Nuclear Information System (INIS)

    In this article, Ga-doped Al-zinc-oxide (GAZO)/titanium-doped indium-tin-oxide (ITIO) bi-layer films were deposited onto glass substrates by direct current (dc) magnetron sputtering. The bottom ITIO film, with a thickness of 200 nm, was sputtered onto the glass substrate. The ITIO film was post-annealed at 350 deg. C for 10-120 min as a seed layer. The effect of post-annealing conditions on the morphologies, electrical, and optical properties of ITIO films was investigated. A GAZO layer with a thickness of 1200 nm was continuously sputtered onto the ITIO bottom layer. The results show that the properties of the GAZO/ITIO films were strongly dependent on the post-annealed conditions. The spectral haze (Tdiffuse/Ttotal) of the GAZO/ITIO bi-layer films increases upon increasing the post-annealing time. The haze and resistivity of the GAZO/ITIO bi-layer films were improved with the post-annealed process. After optimizing the deposition and annealing parameters, the GAZO/ITIO bi-layer film has an average transmittance of 83.20% at the 400-800 nm wavelengths, a maximum haze of 16%, and the lowest resistivity of 1.04 x 10-3Ω cm. Finally, the GAZO/ITIO bi-layer films, as a front electrode for silicon-based thin film solar cells, obtained a maximum efficiency of 7.10%. These encouraging experimental results have potential applications in GAZO/ITIO bi-layer film deposition by in-line sputtering without the wet-etching process and enable the production of highly efficient, low-cost thin film solar cells.

  20. Thermoluminescence of Y{sub 2}O{sub 3}:Tb{sup 3+} thin films deposited by electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Philip R., E-mail: armst230@umn.edu; Mah, Merlin L.; Kim, Sangho S.; Talghader, Joseph J.

    2014-04-15

    Most thermoluminescent materials are created using crystal growth techniques; however, it would be of great utility to identify those few thermoluminescent materials that can be deposited using simpler methods, for example to be compatible with the early portions of a silicon integrated circuit or microelectromechanical fabrication process. In this work, thin films of yttrium oxide with a terbium impurity (Y{sub 2}O{sub 3}:Tb) were deposited on silicon wafers by electron beam evaporation. The source for the Y{sub 2}O{sub 3}:Tb was made by combining Y{sub 2}O{sub 3} and Tb{sub 4}O{sub 7} powders. The approximate thicknesses of the deposited films were 350 nm. After deposition, the films were annealed at 1100 °C for 30 s to improve crystallinity. There is a strong correlation between the x-ray diffraction (XRD) peak intensity and the thermoluminescent glow curve intensity. The glow curve displays at least two peaks at 140 °C and 230 °C. The emission spectra was measured using successive runs with a monochromator set to a different wavelength for each run. There are two main emission peaks at 490 nm and 540 nm. The terbium impurity concentration of approximately 1 mol% was measured using Rutherford backscattering spectrometry (RBS). The Y{sub 2}O{sub 3}:Tb is sensitive to UV, x-ray, and gamma radiation. The luminescent intensity per unit mass of UV irradiated Y{sub 2}O{sub 3}:Tb was about 2 times that of x-ray irradiated TLD-100. -- Highlights: • Y{sub 2}O{sub 3}:Tb{sup 3+} thin film can be deposited using the common microfabrication technique of electron beam evaporation. • The Y{sub 2}O{sub 3}:Tb{sup 3+} requires an anneal of at least 900 °C to show thermoluminescence and 1100 °C anneal for the strongest thermoluminescent signal. • The Y{sub 2}O{sub 3}:Tb{sup 3+} will show a glow curve after being exposed to ionizing radiation from UV, x-ray, and gamma ray sources. • The luminescent intensity per unit mass of the UV irradiated Y{sub 2}O{sub 3}:Tb{sup 3

  1. Evaporation in forced convection of an Ostwaldian permanent laminar film flowing over an isothermal inclined plane surface; Evaporation en convection forcee d'un film liquide mince ostwaldien ruisselant en regime laminaire permanent sur une surface plane isotherme et inclinee

    Energy Technology Data Exchange (ETDEWEB)

    Saouli, Salah [Laboratoire de Valorisation et Promotion des Ressources Sahariennes, Faculte des Sciences et des Sciences de l' Ingenieur, Universite de Ouargla, route de Ghardaia, 30000, Ouargla (Algeria); Boumaza, Mourad [Institut de Genie Climatique, Faculte des Sciences de l' Ingenieur, Universite de Mentouri, route de Ain-El Bey, 25000, Constantine (Algeria); Daguenet, Michel [Laboratoire de Thermodynamique et Energetique, Universite de Perpignan, 52, avenue de Villeneuve, 66860 cedex, Perpignan (France)

    2003-12-01

    The authors study, in forced convection, the evaporation of an Ostwaldian film flowing over an isothermal inclined plane surface to determine the influence of the behaviour index of the liquid on the dynamic and thermal characteristics of liquid-air system. The liquid flow is considered partially two-dimensional whereas for the air it is two-dimensional. The coupled equations with the interfacial conditions are solved using a fully implicit finite differences method. From the study, it appears that the behaviour index influences considerably the transfers which are more important for pseudo-plastic liquids than for dilatant ones. (authors)

  2. Effect of thickness and cold substrate on transport properties of thermally evaporated CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    El-Mongy, A.Abd; Hashem, H.M.; Ramadan, A.A. [Physics Department, Faculty of Science, Helwan University, Helwan, Cairo (Egypt)

    2005-08-01

    The correlation between the structural characteristics (stoichiometry and crystallite size) of CdTe films and their electronic transport properties were the aims of the present study to bring attention to the dual importance of grain size and conversion of the semiconductivity type with changing film thickness. Two main parameters were considered: the substrate temperature and film thickness. Transport properties were influenced by grain boundaries as well as by native doping. Optical measurements showed two main direct transitions at energies: E{sub 1} {approx}1.55 eV (fundamental gap) and E{sub 2}{approx}2.49 eV (due to valence band splitting). Both transitions were found to be thickness dependent with a marked change at a film thickness of about 300 nm. In the case of low substrate temperature, the scaling relation between resistivity and grain size showed a deviation from linear behavior at a size of 20 nm and the transmission coefficient is reduced. Also, the deposition on cold substrate enhanced both dark and photoconductivity for films of thickness {>=}300 nm. It is also proved that the carrier transport was affected by the transmission coef-ficient for carriers to pass a single grain boundary as well as the number of grain boundaries per mean free path. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Fabrication of catalytically active nanocrystalline samarium (Sm)-doped cerium oxide (CeO2) thin films using electron beam evaporation

    International Nuclear Information System (INIS)

    Samarium (Sm)-doped cerium oxide (CeO2) thin films were fabricated using electron beam evaporation technique. The synthesized films were deposited either on glass or ITO substrates and studied their nature by annealing at different temperatures. The optical properties and other morphological studies were done by UV–Vis, XRD, XPS, SEM, EDS, and FT-IR analysis. XRD and XPS analysis clearly confirm the presence of Sm in the ceria site. From the SEM study, it was found that after annealing at high temperature (∼300 or 500 °C), the particles size was reduced due to breakdown of large aggregates of particles which is also confirmed from UV–Vis, XPS, and XRD analyses. The FT-IR study proves the presence of –COO–, –OH, or ammonium group on the particles surface. The deposition of Sm-doped CeO2 nanomaterials was found more feasible on ITO substrate compared to that of glass substrate in terms of stability and depth of film thickness. The Sm-doped CeO2 nanomaterial acts as a re-usable catalyst for the reduction of organic dye molecules in the presence of NaBH4. The catalysis rate was compared by considering the electron transfer process during the reduction. The synthesized Sm-doped CeO2 thin films might find wide variety of applications in various emerging fields like solid oxide fuel cells (SOFCs), oxygen sensor or as catalyst in different types of organic and inorganic catalytic reactions. The fabrication process is very simple, straightforward, less time consuming, and cost effective.Graphical Abstract

  4. YBCO thin film formation near the stability line by resistive evaporation of BaF2, Cu, and Y

    International Nuclear Information System (INIS)

    A single resistivity heated source was used to deposit a mixture of BaF2, Cu, and Y to form precursor films onto MgO substrates held at room temperature. Different heat treatment conditions were applied to study the stability diagram of YBa2Cu3O7-x. It was found that the stability line is shifted toward the higher oxygen partial pressure and lower temperature side of the pure YBCO line in the presence of fluorine and fluorides in the precursor. Films of good quality were obtained when the annealing conditions were in close proximity to this line

  5. Matrix assisted pulsed laser evaporation processing of triacetate-pullulan polysaccharide thin films for drug delivery systems

    Czech Academy of Sciences Publication Activity Database

    Cristescu, R.; Dorcioman, G.; Ristoscu, C.; Axente, E.; Grigorescu, S.; Moldovan, A.; Mihailescu, I. N.; Kocourek, Tomáš; Jelínek, Miroslav; Albulescu, M.; Buruiana, T.; Mihaiescu, D.; Stamatin, I.; Chrisey, D.B.

    2006-01-01

    Roč. 252, - (2006), s. 4647-4651. ISSN 0169-4332 Institutional research plan: CEZ:AV0Z10100522 Keywords : polysaccharide * pullulan * thin films * laser deposition * MAPLE * drug delivery Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.436, year: 2006

  6. Structural and optical properties of Tris(8-hydroxyquinoline) aluminum (III) (Alq{sub 3}) thermal evaporated thin films

    Energy Technology Data Exchange (ETDEWEB)

    El-Nahass, M.M. [Physics Department, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt); Farid, A.M., E-mail: ashganfarid@hotmail.co [Physics Department, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt); Atta, A.A. [Physics Department, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt)

    2010-09-24

    X-ray diffraction (XRD), transmission electron microscope (TEM) micrographs and optical properties of Tris(8-hydroxyquinoline) aluminum (III) (Alq{sub 3}) have been studied. XRD of powder Alq{sub 3} showed that the material has a polycrystalline nature with triclinic structure. The crystal structure and morphology of the as-deposited and annealed (at 473 K for 2 h.) Alq{sub 3} thin films indicated that the as-deposited film is amorphous in nature, while the annealed film has a polycrystalline nature with amorphous background. The molecular structure of the Alq{sub 3} was confirmed by the analysis of (FTIR) spectra. The optical constants such as the refractive index, n, the absorption index, k and the absorption coefficient, {alpha}, of both the amorphous and polycrystalline Alq{sub 3} films were determined using spectrophotometric measurements of transmittance (T) and reflectance (R) in the wavelength range (200-2500 nm). The analysis of the data showed an indirect allowed transition energy gaps E{sub g}{sup ind} of 2.66 eV and 2.28 eV for the as-deposited and the annealed Alq{sub 3} thin films, respectively. As well as another probability of direct allowed transition was carried out with energy gaps Eg{sub 1}{sup d} of 2.82 eV, and Eg{sub 2}{sup d} of 4.14 eV for the as-deposited film and Eg{sub 1}{sup d} of 2.59 eV, Eg{sub 2}{sup d} of 3.88 eV for the annealed films, respectively. Some optical parameters namely molar extinction coefficient ({epsilon}{sub molar}), oscillator strength (f) and electric dipole strength (q{sup 2}) have been evaluated. According to the single oscillator model (SOM), some related parameters such as oscillation energy (E{sub 0}), the dispersion energy (E{sub d}), the optical dielectric constant ({epsilon}{sub {infinity}}), the lattice dielectric constant ({epsilon}{sub L}) and the ratio of free carrier concentration to its effective mass (N/m*) were estimated. Graphical representation of both the surface and volume energy loss functions

  7. Enhanced bone forming ability of SLA-treated Ti coated with a calcium phosphate thin film formed by e-beam evaporation

    International Nuclear Information System (INIS)

    With an electron-beam evaporation process, a calcium phosphate (Ca-P) thin film of ∼500 nm thick was deposited on sand blasted with large grits and acid etched (SLA) Ti without changing the typical morphology of the SLA surface. Dissolution behavior was investigated by measuring the amount of dissolved phosphate ions with ion chromatography after immersing the SLA Ti sample coated with a Ca-P film in 1 ml de-ionized water maintained at 37 0C for different periods of soaking time, and the surface morphology was observed with field emission scanning electron microscopy. The amount of phosphate ions increased quickly right after immersion but began to decrease after 2 days of immersion by redeposition with Ca ions as apatite, and the amount of biomimetic apatite increased with the extended soaking time. The Saos-2 cell was more attached on the coated surface, and the in vivo evaluation was that the Ca-P deposited SLA implant greatly improved the new bone formation ability.

  8. Enhanced bone forming ability of SLA-treated Ti coated with a calcium phosphate thin film formed by e-beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeongil [Restorative Dentistry, School of Dental Medicine, University at Buffalo, NY 14214 (United States); Choi, Seong-Ho [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul 120-752 (Korea, Republic of); Chung, Sung-Min; Li, Long-Hao [Dentium Clinic Implantium Institute, Seoul 135-879 (Korea, Republic of); Lee, In-Seop, E-mail: inseop@yonsei.ac.k [Atomic-Scale Surface Science Research Center, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2010-08-01

    With an electron-beam evaporation process, a calcium phosphate (Ca-P) thin film of {approx}500 nm thick was deposited on sand blasted with large grits and acid etched (SLA) Ti without changing the typical morphology of the SLA surface. Dissolution behavior was investigated by measuring the amount of dissolved phosphate ions with ion chromatography after immersing the SLA Ti sample coated with a Ca-P film in 1 ml de-ionized water maintained at 37 {sup 0}C for different periods of soaking time, and the surface morphology was observed with field emission scanning electron microscopy. The amount of phosphate ions increased quickly right after immersion but began to decrease after 2 days of immersion by redeposition with Ca ions as apatite, and the amount of biomimetic apatite increased with the extended soaking time. The Saos-2 cell was more attached on the coated surface, and the in vivo evaluation was that the Ca-P deposited SLA implant greatly improved the new bone formation ability.

  9. Eects of Post Deposition Treatments on Vacuum Evaporated CdTe Thin Films and CdS=CdTe Heterojunction Devices

    Science.gov (United States)

    Bayhan, Habibe; Erçelebý, Çiðdem

    1998-05-01

    CdTe, CdS thin films and n-CdS/p-CdTe heterostructures have been prepared by conventional vacuum evaporation technique. Some post deposition treatments to optimize the device efficiency have been analyzed and the effects of the individual process steps on the material and device properties were investigated. Annealing in air with and without CdCl2-treatment decreased the CdTe resistivity. The CdCl2-dip followed by annealing in air at 300°C for 5 min improved the grain size and polycrystalline nature of CdTe thin films. Solar efficiency improvements were achieved when heterojunctions were prepared on successively treated (i.e. etched, air annealed, CdCl2-processed) CdTe surfaces. Etching of the CdTe surface with potassium dichromate solution prior to metal contact deposition lead to the formation of low-resistance Au contacts and increase in open circuit voltage and fill factor values.

  10. Study of annealing effects on the physical properties of evaporated SnS thin films for photovoltaic applications

    OpenAIRE

    Tariq, GH; Hutchings, K; Asghar, G; Lane, DW; Anis-ur-Rehman, M.

    2014-01-01

    Tin Sulphide (SnS) thin films have been deposited on glass slides by thermal evaporation using SnS powder. The improvements in the structural and optical properties of SnS thin films on annealing at different temperatures (200 degrees C, 300 degrees C, 400 degrees C, and 500 degrees C) in vacuum for one hour are presented in this work. The thin films annealed at 500 degrees C were decomposed, which limits the annealing temperature below than 500 degrees C. X-ray diffraction characterization s...

  11. Study of a sandwich structure of transparent conducting oxide films prepared by electron beam evaporation at room temperature

    OpenAIRE

    Chiu, Po Kai; Cho, Wen Hao; Chen, Hung Ping; Hsiao, Chien Nan; Yang, Jer Ren

    2012-01-01

    Transparent conducting ZnO/Ag/ZnO multilayer electrodes having electrical resistance much lower than that of widely used transparent electrodes were prepared by ion-beam-assisted deposition (IAD) under oxygen atmosphere. The optical parameters were optimized by admittance loci analysis to show that the transparent conducting oxide (TCO) film can achieve an average transmittance of 93%. The optimum thickness for high optical transmittance and good electrical conductivity was found to be 11 nm ...

  12. Matrix assisted pulsed laser evaporation of pullulan tailor-made biomaterial thin films for controlled drug delivery systems

    Czech Academy of Sciences Publication Activity Database

    Cristescu, R.; Jelínek, Miroslav; Kocourek, Tomáš; Axente, E.; Grigorescu, S.; Moldovan, A.; Mihaiescu, D.E.; Albulescu, M.; Buruiana, T.; Dybal, Jiří; Stamatin, I.; Mihailescu, I. N.; Chrisey, D.B.

    2007-01-01

    Roč. 59, - (2007), s. 144-149. ISSN 1742-6588 R&D Projects: GA AV ČR IAA1010110 Grant ostatní: CTU(CZ) 6640770030; CERES(RO) 4-178/15.11.2004 Institutional research plan: CEZ:AV0Z10100522; CEZ:AV0Z40500505 Keywords : pulluan * thin films * MAPLE Subject RIV: BM - Solid Matter Physics ; Magnetism

  13. Effect of Annealing On Thin Film Fabrication of Cadmium Zinc Telluride by Single-R.F. Magnetron Sputtering Unit

    Directory of Open Access Journals (Sweden)

    Dr. Monisha Chakraborty A,

    2014-01-01

    Full Text Available In this work, formation of Cd1-xZnxTe thin films under various annealing-environments, created by layer by layer deposition of individual CdTe and ZnTe targets from a Single-R.F. Magnetron Sputtering unit is investigated. Structural and optical characterization results show that Vacuum Annealing is the best suitable for the formation of better Cd1-xZnxTe XRD peaks of higher intensities in comparison to Argon or Nitrogen-Annealing, for a bi-layered deposited CdTe and ZnTe film on glass substrate. The crystallography of the Cd1-xZnxTe films formed appeared to be either Cubic or Rhombohedral type. Also, it has been noticed, that the more inert the annealing-environment is, the lesser is the heat loss by the film-substrate and this results in better fusing of the deposited particles to move more from the poly-crystalline to the mono-crystalline structure. Also higher inert environment causes more Cadmium evaporation and this consequently drives the lattice-constant and the band-gap energy of the formed Cd1-xZnxTe thin film to move from the CdTe side to the ZnTe side. The method developed here with proper annealing ambiance for Cd1-xZnxTe fabrication can be implemented in laboratories lacking in Co-Sputtering machine.

  14. Controlling interfacial curvature in nanoporous silica films formed by evaporation-induced self-assembly from nonionic surfactants. I. Evolution of nanoscale structures in coating solutions.

    Science.gov (United States)

    Bollmann, Luis; Urade, Vikrant N; Hillhouse, Hugh W

    2007-04-10

    The double-gyroid phase of nanoporous silica films formed by evaporation-induced self-assembly (EISA) has been shown to possess facile mass-transport properties and may be used as a robust template for the nanofabrication of metal and semiconductor nanostructures. Recently, we developed a new synthesis of double-gyroid nanoporous silica films where the aging time of the coating solution prior to EISA was the key parameter required to control the interfacial curvature that results upon self-assembly of the film. Here, we use 29Si nuclear magnetic resonance (NMR) and small-angle X-ray scattering (SAXS) to investigate the nanoscale structure of the coating solutions used to obtain double-gyroid nanoporous silica films. NMR and SAXS were carried out on the water, ethanol, silica, and poly(ethylene oxide)-b-poly(propylene oxide)-b-alkyl (EO17-PO12-C14) surfactant coating solutions as well as similar solutions that excluded either the silica or the surfactant. NMR data reveal that the silica monomers in the coating solution condense very rapidly to form rings and connected ring species. After 1 day of aging, all monomers and dimers have disappeared, and the distribution is dominated by Q2 and Q3 species, where the superscript in Qn describes the number of silicon atoms in the second coordination shell of the central silicon. Over the course of the next 9 days, the Q3 population slowly rises at the expense of the Q2 and Q3t populations. Absolute intensity SAXS measurements reveal that the size of the silica clusters increases steadily during this aging period, reaching an average radius of gyration of 9.0 A after 9 days of aging. Longer aging results in the continued growth of clusters with a mass fractal dimension of 1.8. Absolute intensity SAXS data also reveals that micelles are not present in the coating solution. At 9% volume fraction of surfactant, the coating solution is far above the aqueous critical micellar concentration. However, even a small amount of ethanol

  15. Physical properties of Cdsub(1-x)Znsub(x)S thin films prepared by thermal evaporation of the solid solution

    International Nuclear Information System (INIS)

    In order to realize Cu2S-CdZnS solar cells, Cdsub(1-x)Znsub(x)S polycrystalline layers are prepared by means of conventional thermal evaporation of suitable CdZnS solid solutions (0 <= x <= 0.2) on different substrates. The influence of the ZnS concentration on the layer physical properties is determined by X-ray patterns, by SEM and TEM observations, by electrical and photoelectrical measurements versus temperature (thermally stimulated conductivity, spectral photosensitivity of the photoconduction, ...), by capacitance measurements of CdZnS/Au diodes, by optical spectrometry of the band gap, and the free carrier absorption. When the ZnS concentration x increases, the crystallization is modified, the energy gap and the activation energy of the donor levels increases, the dark longitudinal conductivity and the photosensitivity decreases. The photoconduction time constant increases. Paradoxally, the free electron density, determined by three independent methods, increases with ZnS concentration up to a saturation value for x approximately 0.15. (author)

  16. Research on the Comprehensive Heat Transfer Coefficient of Horizontal Tube Falling Film Evaporator%水平管降膜蒸发器综合传热系数研究

    Institute of Scientific and Technical Information of China (English)

    邹龙生; 谢加才; 周伟国; 陈德珍

    2011-01-01

    介绍了油田废水的特性及主要成分的参数值.基于在水平管降膜蒸发器传热性能研究现状的基础上,以及热法高倍数蒸发浓缩油田废水的具体任务与要求,建立水平管降膜蒸发器传热系数与污垢热阻的模型,通过有关方程建立污垢热阻与蒸发浓缩时浓度变化的关联式.依据各部分的关联式,经过详细推导,得到水平管降膜蒸发器综合传热系数关联式.根据物理模型和关联式,讨论浓缩倍数和流量变化对水平管降膜蒸发器综合传热系数的影响.结果表明:在蒸发浓缩油田废水时,浓缩倍数的提高降低了水平管降膜蒸发器的综合传热系数.油田废水处理量的增加,在一定程度上强化了水平管降膜蒸发器的传热效率.模拟计算得到水平管降膜蒸发器的综合传热系数在936~940 W/(m2·K)的范围内.%The characteristics of oil-field wastewater and parameter values of primary component were introduced. Based on the research status on heat transfer performances of the horizontal tube falling film evaporator, and the specific tasks and requirements of high multiples of evaporated and concentrated oil-field wastewater by the thermal method, the heat transfer coefficient of horizontal tube falling film evaporator and the modeling of fouling resistance were established; the correlation equations of fouling resistance and concentration variations during the process of evaporation and concentration were also established through the relevant equations. According to each part of the correlation equations, the correlation of the comprehensive heat transfer coefficient of the horizontal tube falling film evaporators was derived by detail derivation. Based on the physical model and correlation, the influence of concentration factors and flow changes on the comprehensive heat transfer coefficients of the horizontal tube falling film evaporators were discussed. The results show that the comprehensive heat

  17. Evaporating firewalls

    Science.gov (United States)

    Van Raamsdonk, Mark

    2014-11-01

    In this note, we begin by presenting an argument suggesting that large AdS black holes dual to typical high-energy pure states of a single holographic CFT must have some structure at the horizon, i.e. a fuzzball/firewall, unless the procedure to probe physics behind the horizon is state-dependent. By weakly coupling the CFT to an auxiliary system, such a black hole can be made to evaporate. In a case where the auxiliary system is a second identical CFT, it is possible (for specific initial states) that the system evolves to precisely the thermofield double state as the original black hole evaporates. In this case, the dual geometry should include the "late-time" part of the eternal AdS black hole spacetime which includes smooth spacetime behind the horizon of the original black hole. Thus, if a firewall is present initially, it evaporates. This provides a specific realization of the recent ideas of Maldacena and Susskind that the existence of smooth spacetime behind the horizon of an evaporating black hole can be enabled by maximal entanglement with a Hawking radiation system (in our case the second CFT) rather than prevented by it. For initial states which are not finely-tuned to produce the thermofield double state, the question of whether a late-time infalling observer experiences a firewall translates to a question about the gravity dual of a typical high-energy state of a two-CFT system.

  18. Optical and structural study of In{sub 2}S{sub 3} thin films growth by co-evaporation and chemical bath deposition (CBD) on Cu{sub 3}BiS{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mesa, F., E-mail: fgmesar@unal.edu.co [Unidad de Estudios Universitarios, Colegio Mayor de Nuestra Señora del Rosario, Cra. 24 N° 63C-69, Bogotá (Colombia); Chamorro, W. [Université de Lorraine, Institut Jean Lamour, Nancy (France); Hurtado, M. [Departamento de Quimica, Universidad Nacional de Colombia, Cra. 30 N° 45-03, Bogotá (Colombia); Departamento de Física, Universidad de los Andes, Calle 21 No. 1-20, Bogotá (Colombia)

    2015-09-30

    Highlights: • In{sub 2}S{sub 3} thin films usually grow like an ultrathin. • Samples grown by CBD have a higher degree of coverage of the substrate unlike co-evaporation method. • Solar cells of Al/TCO/In{sub 2}S{sub 3}/Cu{sub 3}BiS{sub 3}/Mo structure. • In{sub 2}S{sub 3} thin films were deposited on Cu{sub 3}BiS{sub 3} (CBS), with of In{sub 2}S{sub 3} β-phase with tetragonal structure. - Abstract: We present the growth of In{sub 2}S{sub 3} onto Cu{sub 3}BiS{sub 3} layers and soda-lime glass (SLG) substrates by using chemical bath deposition (CBD) and physical co-evaporation. The results reveal that the microstructure and the optical properties of the In{sub 2}S{sub 3} films are highly dependent on the growth method. X-ray diffractrograms show that In{sub 2}S{sub 3} films have a higher crystallinity when growing by co-evaporation than by CBD. In{sub 2}S{sub 3} thin films grown by CBD with a thickness below 170 nm have an amorphous structure however when increasing the thickness the films exhibit two diffraction peaks associated to the (1 0 3) and (1 0 7) planes of the β-In{sub 2}S{sub 3} tetragonal structure. It was also found that the In{sub 2}S{sub 3} films present an energy bandgap (E{sub g}) of about 2.75 eV, regardless of the thickness of the samples.

  19. Growth of Large-Area Single- and Bi-Layer Graphene by Controlled Carbon Precipitation on Polycrystalline Ni Surfaces

    OpenAIRE

    Reina, Alfonso; Thiele, Stefan; Jia, Xiaoting; Bhaviripudi, Sreekar; Dresselhaus, Mildred S.; Schaefer, Juergen A.; Kong, Jing

    2009-01-01

    We report graphene films composed mostly of one or two layers of graphene grown by controlled carbon precipitation on the surface of polycrystalline Ni thin films during atmospheric chemical vapor deposition (CVD). Controlling both the methane concentration during CVD and the substrate cooling rate during graphene growth can significantly improve the thickness uniformity. As a result, one- or two- layer graphene regions occupy up to 87% of the film area. Single layer coverage accounts for 5%–...

  20. Origins of Highly Stable Al-evaporated Solution-processed ZnO Thin Film Transistors: Insights from Low Frequency and Random Telegraph Signal Noise

    Science.gov (United States)

    Kim, Joo Hyung; Kang, Tae Sung; Yang, Jung Yup; Hong, Jin Pyo

    2015-11-01

    One long-standing goal in the emerging field of flexible and transparent electronic devices is to meet the demand of key markets, such as enhanced output performance for metal oxide semiconductor thin film transistors (TFTs) prepared by a solution process. While solution-based fabrication techniques are cost-effective and ensure large-area coverage at low temperature, their utilization has the disadvantage of introducing large trap states into TFTs. Such states, the formation of which is induced by intrinsic defects initially produced during preparation, have a significant impact on electrical performance. Therefore, the ability to enhance the electrical characteristics of solution-processed TFTs, along with attaining a firm understanding of their physical nature, remains a key step towards extending their use. In this study, measurements of low-frequency noise and random telegraph signal noise are employed as generic alternative tools to examine the origins of enhanced output performance for solution-processed ZnO TFTs through the control of defect sites by Al evaporation.

  1. Group evaporation

    Science.gov (United States)

    Shen, Hayley H.

    1991-01-01

    Liquid fuel combustion process is greatly affected by the rate of droplet evaporation. The heat and mass exchanges between gas and liquid couple the dynamics of both phases in all aspects: mass, momentum, and energy. Correct prediction of the evaporation rate is therefore a key issue in engineering design of liquid combustion devices. Current analytical tools for characterizing the behavior of these devices are based on results from a single isolated droplet. Numerous experimental studies have challenged the applicability of these results in a dense spray. To account for the droplets' interaction in a dense spray, a number of theories have been developed in the past decade. Herein, two tasks are examined. One was to study how to implement the existing theoretical results, and the other was to explore the possibility of experimental verifications. The current theoretical results of group evaporation are given for a monodispersed cluster subject to adiabatic conditions. The time evolution of the fluid mechanic and thermodynamic behavior in this cluster is derived. The results given are not in the form of a subscale model for CFD codes.

  2. A pore network study on water distribution in bi-layer gas diffusion media: Effects of inlet boundary condition and micro-porous layer properties

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Rui; Zhu, Xun; Liao, Qiang; Wang, Hong; Ding, Yu-dong; Li, Jun; Ye, Ding-ding [Institute of Engineering Thermophysics, Chongqing University, Chongqing 400044 (China)

    2010-09-15

    Water flooding in gas diffusion material (GDM) is an important limit in performance of proton exchange membrane fuel cell (PEFMC). Some efforts, such as modifying the pore structures in the GDM, have been made in order to facilitate water transport and to reduce flooding in PEMFC. Recent experimental studies have demonstrated that using a bi-layer GDM, consisting of a fine micro-porous layer (MPL) and a coarse gas diffusion layer (GDL), can be advantageous for water management in PEMFC. In this work, a pore network model with an invasion percolation algorithm is developed and used to investigate the effects of MPL properties, including thickness, wettability and connectivity, on water distribution in the bi-layer GDM from the viewpoint at the pore level. Furthermore, a reasonable inlet boundary condition is proposed to describe the actual phenomenon that the CL surface is covered with many independent water droplets which are much larger than pore sizes in MPL. Influences of water droplet size and coverage fraction are also clarified in the present study. (author)

  3. Stabilization criteria for cubic AlN in TiN/AlN and CrN/AlN bi-layer systems

    International Nuclear Information System (INIS)

    We combine the finite element (ABAQUS) and ab initio methods to study and predict the equilibrium critical thickness up to which the metastable cubic (c) AlN phase is energetically favoured to the stable wurtzite (w) variant in TiN/AlN and CrN/AlN bi-layer systems. The results show that the w-AlN phase is preferred for all thicknesses in the free-standing configuration (without a substrate) when grown on TiN, while 4 nm thick c-AlN is predicted for CrN bi-layer material systems. The substrate helps to stabilize c-AlN up to 15.8 nm, and for an incoherent interface between the substrate and the TiN or CrN interlayer, the stabilization mechanically supports the interlayer against relaxation. For a coherent interface to the substrate, a small lattice constant (as, e.g., in the case of Al substrate) helps to stabilize c-AlN, whereas a large lattice constant (as, e.g., in the case of MgO) promotes w-AlN. Finally, we predict that 〈111〉 orientated specimens allow for thicker c-AlN layers than those grown along the 〈100〉 direction.

  4. Effect of the spin-twist structure on the spin-wave dynamics in Fe{sub 55}Pt{sub 45}/Ni{sub 80}Fe{sub 20} exchange coupled bi-layers with varying Ni{sub 80}Fe{sub 20} thickness

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Semanti; Barman, Saswati, E-mail: saswati@bose.res.in; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology and Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sec III, Salt Lake, Kolkata 700098 (India); Hellwig, Olav [San Jose Research Center, HGST, a Western Digital Company, 3403 Yerba Buena Rd., San Jose, California 95135 (United States)

    2014-05-07

    We have investigated optically induced ultrafast magnetization dynamics of a series of Fe{sub 55}Pt{sub 45}/Ni{sub 80}Fe{sub 20} exchange spring bi-layers with varying Ni{sub 80}Fe{sub 20} thickness. Rich spin-wave spectra are observed; whose frequency shows a strong dependence on the Ni{sub 80}Fe{sub 20} layer thickness. Micromagnetic simulations based on a simplified magnetic microstructure were able to reproduce the experimental data qualitatively. The spin twist structure introduced in the Ni{sub 80}Fe{sub 20} layer gives rise to new modes in the composite system as opposed to the bare Ni{sub 80}Fe{sub 20} films.

  5. Bi-layer structure of counterstreaming energetic electron fluxes: a diagnostic tool of the acceleration mechanism in the Earth's magnetotail

    Directory of Open Access Journals (Sweden)

    D. V. Sarafopoulos

    2010-02-01

    Full Text Available For the first time we identify a bi-layer structure of energetic electron fluxes in the Earth's magnetotail and establish (using datasets mainly obtained by the Geotail Energetic Particles and Ion Composition (EPIC/ICS instrument that it actually provides strong evidence for a purely spatial structure. Each bi-layer event is composed of two distinct layers with counterstreaming energetic electron fluxes, parallel and antiparallel to the local ambient magnetic field lines; in particular, the tailward directed fluxes always occur in a region adjacent to the lobes. Adopting the X-line as a standard reconnection model, we determine the occurrence of bi-layer events relatively to the neutral point, in the substorm frame; four (out of the shown seven events are observed earthward and three tailward, a result implying that four events probably occurred with the substorm's local recovery phase. We discuss the bi-layer events in terms of the X-line model; they add more constraints for any candidate electron acceleration mechanism. It should be stressed that until this time, none proposed electron acceleration mechanism has discussed or predicted these layered structures with all their properties. Then we discuss the bi-layer events in terms of the much promising "akis model", as introduced by Sarafopoulos (2008. The akis magnetic field topology is embedded in a thinned plasma sheet and is potentially causing charge separation. We assume that as the Rc curvature radius of the magnetic field line tends to become equal to the ion gyroradius rg, then the ions become non-adiabatic. At the limit Rc=rg the demagnetization process is also under way and the frozen-in magnetic field condition is violated by strong wave turbulence; hence, the ion particles in this geometry are stochastically scattered. In addition, ion diffusion probably takes place across the magnetic field, since an

  6. Effect of post-sulfurization on the structural and optical properties of Cu{sub 2}ZnSnS{sub 4} thin films deposited by vacuum evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Touati, R., E-mail: rym.touati@gmail.com [Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, ENIT, BP 37, le Belvédère, 1002 Tunis (Tunisia); Ben Rabeh, M. [Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, ENIT, BP 37, le Belvédère, 1002 Tunis (Tunisia); Kanzari, M. [Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, ENIT, BP 37, le Belvédère, 1002 Tunis (Tunisia); Laboratoire de Photovoltaïques et Matériaux Semi-conducteurs, ENIT, IPEITunis Montfleury, Université de Tunis (Tunisia)

    2015-05-01

    The influence of post deposition annealing in sulfur atmosphere on the structural and optical properties of Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films was investigated. The samples were deposited by thermal evaporation under vacuum method at different glass substrate temperatures ranging from 60 °C to 210 °C. After the deposition, all CZTS thin films were annealed in a furnace in sulfur atmosphere at a temperature of 400 °C during 2 h so as to optimize the kesterite CZTS phase. Structural characterization was carried out using X-ray diffraction and Raman Scattering whereas optical characterization was performed by recording transmittance and reflectance of the samples in the spectral range of 300 nm-2400 nm. The X-ray diffraction spectra indicated that polycrystalline CZTS films were obtained after annealing and the samples exhibit (112) preferred diffraction plane. Hence, crystallinity was enhanced with substrate temperature as well as with post deposition annealing due to the diffusion of sulfur in the film during the annealing process. Optical study reveals that after annealing, the absorption coefficient is found to be higher than 10{sup 5} cm{sup −1} whereas the direct band gap energy varies in the range of 1.4 eV-1.6 eV. - Highlights: • Growth of Cu{sub 2}ZnSnS{sub 4} (CZTS) films on heated substrates by thermal evaporation method • Annealing of CZTS thin films in sulfur vapor under vacuum at 400 °C • XRD and Raman results revealed that Kesterite CZTS is the major crystalline phase. • Post-annealed films demonstrated a high absorption coefficient (> 10{sup 4} cm{sup −1}). • Post-annealed films showed an optical band gap between 1.46 eV and 1.66 eV.

  7. Method of evaporation

    Science.gov (United States)

    Dufresne, Eugene R.

    1987-01-01

    Liquids, such as juices, milk, molten metal and the like are concentrated by forming uniformly-sized, small droplets in a precision droplet forming assembly and deploying the droplets in free fall downwardly as a central column within an evacuated column with cool walls. A portion of the solvent evaporates. The vapor flows to the wall, condenses, and usually flows down the wall as a film to condensate collector and drain. The vertical column of freely falling droplets enters the splash guard. The condensate can be collected, sent to other towers or recycled.

  8. Structural and spectroscopic ellipsometry studies on vacuum-evaporated Sn2m−4Sb4S2m+2 (m = 2.5, 3 and 4) thin films deposited on glass and Si substrates

    International Nuclear Information System (INIS)

    Sn2m−4Sb4S2m+2 (m = 2.5, 3 and 4) thin films were deposited on glass and Si substrates using vacuum evaporation technique. The structural properties have been investigated by X-ray diffraction (XRD) and Raman spectroscopy. The XRD patterns revealed the polycrystalline nature of the films on substrates even when they are not heated during evaporation process. Raman spectra revealed four main peaks. The main structural units of Sn–Sb–S thin films are tetrahedral [SnS4] and pyramidal [SbS3]. The cross-section morphology was obtained by scanning electron microscopy (SEM). Spectroscopic ellipsometry (SE) measurements (ψ and Δ) were carried out to study the optical properties of the films. SE measured data were analyzed by considering double layer optical model for all the samples, with the two oscillators Tauc-Lorentz and Gaussian dispersion relations. Surface roughness was taken into consideration as shown in SEM micrographs. From the ellipsometric study, we determined the thicknesses of the modeled layers and their optical parameters (refractive index, absorption coefficient …). All the films exhibit high absorption coefficient α in the visible range (>105 cm−1). The values of the band gap energy Eg of Sn2m−4Sb4S2m+2 thin films deposited on glass were 1.52, 1.29 and 1.28 eV, respectively for m = 2.5, 3 and 4. For the samples deposited on silicon, Eg(SnSb4S7) = 1.29 eV, Eg(SnSb2S4) = 1.13 eV and Eg(Sn2Sb2S5) = 1.48 eV. - Highlights: • Sn2m−4Sb4S2m+2 films were thermally evaporated on glass and Si substrates. • The films have polycrystalline nature without any heat treatment. • [SnS4] tetrahedral and [SbS3] pyramidal are the main structural units. • Thicknesses and optical parameters were determined by ellipsometric study. • The films exhibit high absorption coefficient α in the visible range (>105 cm−1)

  9. Structural and spectroscopic ellipsometry studies on vacuum-evaporated Sn{sub 2m−4}Sb{sub 4}S{sub 2m+2} (m = 2.5, 3 and 4) thin films deposited on glass and Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Abdelkader, D., E-mail: dhaferabdelkader@gmail.com [Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs-ENIT, Université Tunis ElManar, BP37, Lebelvédère, 1002 Tunis (Tunisia); Akkari, F. Chaffar; Khemiri, N. [Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs-ENIT, Université Tunis ElManar, BP37, Lebelvédère, 1002 Tunis (Tunisia); Gallas, B. [Institut des NanoSciences de Paris-CNRS-Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05 (France); Antoni, F. [ICube-Laboratoire des sciences de l’Ingénieur, de l' Informatique et de l’Imagerie, Université de Strasbourg-CNRS, 23, rue du Loess, 67037 Strasbourg Cedex (France); Kanzari, M. [Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs-ENIT, Université Tunis ElManar, BP37, Lebelvédère, 1002 Tunis (Tunisia); Institut Préparatoire aux Etudes d' Ingénieurs de Tunis-IPEIT, Université de Tunis, 2, Rue Jawaher Lel Nehru, 1089 Montfleury (Tunisia)

    2015-10-15

    Sn{sub 2m−4}Sb{sub 4}S{sub 2m+2} (m = 2.5, 3 and 4) thin films were deposited on glass and Si substrates using vacuum evaporation technique. The structural properties have been investigated by X-ray diffraction (XRD) and Raman spectroscopy. The XRD patterns revealed the polycrystalline nature of the films on substrates even when they are not heated during evaporation process. Raman spectra revealed four main peaks. The main structural units of Sn–Sb–S thin films are tetrahedral [SnS{sub 4}] and pyramidal [SbS{sub 3}]. The cross-section morphology was obtained by scanning electron microscopy (SEM). Spectroscopic ellipsometry (SE) measurements (ψ and Δ) were carried out to study the optical properties of the films. SE measured data were analyzed by considering double layer optical model for all the samples, with the two oscillators Tauc-Lorentz and Gaussian dispersion relations. Surface roughness was taken into consideration as shown in SEM micrographs. From the ellipsometric study, we determined the thicknesses of the modeled layers and their optical parameters (refractive index, absorption coefficient …). All the films exhibit high absorption coefficient α in the visible range (>10{sup 5} cm{sup −1}). The values of the band gap energy E{sub g} of Sn{sub 2m−4}Sb{sub 4}S{sub 2m+2} thin films deposited on glass were 1.52, 1.29 and 1.28 eV, respectively for m = 2.5, 3 and 4. For the samples deposited on silicon, E{sub g}(SnSb{sub 4}S{sub 7}) = 1.29 eV, E{sub g}(SnSb{sub 2}S{sub 4}) = 1.13 eV and E{sub g}(Sn{sub 2}Sb{sub 2}S{sub 5}) = 1.48 eV. - Highlights: • Sn{sub 2m−4}Sb{sub 4}S{sub 2m+2} films were thermally evaporated on glass and Si substrates. • The films have polycrystalline nature without any heat treatment. • [SnS{sub 4}] tetrahedral and [SbS{sub 3}] pyramidal are the main structural units. • Thicknesses and optical parameters were determined by ellipsometric study. • The films exhibit high absorption coefficient α in the visible

  10. Ultra-large current transport in thick SmBa2Cu3O7−x films grown by reactive co-evaporation

    International Nuclear Information System (INIS)

    Highlights: • Transport properties of 5 μm thick SmBa2Cu3O7−x thin films were investigated. • Laser scanning microscopy was used to demonstrate local transport properties. • Temperature variable laser scanning microscopy shows correlation between structural and transport properties. • Optical measurements described nature of current transport properties in the coated conductors. - Abstract: Structural and transport properties of high performance SmBa2Cu3O7−x coated conductors produced by a dual-chamber co-evaporation are presented. The 5 μm-thick SmBCO coated conductors grown on IBAD-MgO based Hastelloy metal templates show critical currents larger than 1020–1560 A/cm at 77 K and self-field. The current transport characteristics of the conductors are investigated by room-temperature thermoelectric microscopy and low-temperature bolometric microscopy. The local thermoelectric images show the tilted grains, grain boundaries, and microstructural defects on the surface of the coated conductors. The bias current-dependent bolometric response at low temperature displays the current of the local flux flow dissipation as an increasing bias. Furthermore, we measured micro-Raman scattering microscopic imaging on oxygen-related peaks of the conductors. Comparing the Raman signal images with the low temperature optical scanning maps, it is remarkable that the structural disorders represented by oxygen-related Raman peaks are closely related to the low temperature bolometric abnormalities. From this result, a nature of the dissipative current distribution in coated conductors is revealed. The scanning optical microscopic study will provide a promising method for quality assurance of coated conductors

  11. Diffusion-driven evaporation of sessile drops

    International Nuclear Information System (INIS)

    The evaporation of wetting drops deposited on a substrate at thermal equilibrium under normal atmosphere is discussed. The evaporation rate appears to be controlled by the stationary diffusion of vapour molecules in the gas phase. Experiments with alkanes and water drops are fairly well accounted for by an isothermal model, taking into account the specific properties of thin films

  12. 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.

  13. Evaporation reduction from tritiated water pools

    International Nuclear Information System (INIS)

    Spent-fuel storage and disassembly basins at heavy water reactor facilities have maximum allowable temperature and tritium activity levels to protect personnel from exposure to radiation from the tritiated water vapor emanating from these basins. Means of reducing this exposure by suppressing basin water evaporation through the use of monolayer films are presented. The effect of tritiated water on the performance of the monolayer film has been experimentally examined, and tritiated water does not detrimentally affect the film's ability to reduce evaporation. Large-scale light water experiments have demonstrated that an octadecanol monolayer can reduce evaporation by ∼50%. A method for applying and maintaining a monolayer film over large areas with complex surface geometries has been developed. The results demonstrate the feasibility of using octadecanol monolayers to suppress evaporation from tritiated water pools

  14. Denton E-beam Evaporator #1

    Data.gov (United States)

    Federal Laboratory Consortium — Description: CORAL Name: E-Beam Evap 1 This is a dual e-beam/thermal evaporator for the deposition of metal and dielectric thin films. Materials available are: Ag,...

  15. Denton E-beam Evaporator #2

    Data.gov (United States)

    Federal Laboratory Consortium — Description: CORAL Name: E-Beam Evap 2 This is an electron gun evaporator for the deposition of metals and dielectrics thin films. Materials available are: Ag, Al,...

  16. Numerical study of the evaporation in laminar humid air flow of a liquid film flowing over an inclined plate; Etude numerique de l'evaporation dans un courant d'air humide laminaire d'un film d'eau ruisselant sur une plaque inclinee

    Energy Technology Data Exchange (ETDEWEB)

    Hacene Mezaache, E. [Centre Universitaire de Skikda (Algeria); Daguenet, M. [Universite de Perpignan, Lab. de Thermodynamique et Energetique, 66 - Perpignan (France)

    2000-01-01

    By using an implicit centered finite differences method with a non-uniform grid, the authors study numerically the evaporation of a thin liquid film flowing over an inclined plate in a forced humid-air flow. They consider the existence of two-dimensional laminar boundary-layers with variable physical properties and show that the term of enthalpy diffusion is always negligible, whether the plate is adiabatic, isothermal or heated by a constant heat flux density. By using in the liquid film transfer equations which are one-dimensional, partially two-dimensional and two-dimensional, the authors additionally show the following features. If the plate is adiabatic, the liquid mass flow rate is without influence on the transfers and the gas-liquid interface behaves like an isotherm surface at rest. In this case, one may use a one-dimensional model in the film whatever liquid mass flow rate is. If the wall is isotherm or heated by a constant heat flux and when the liquid mass flow rate is less than 10{sup -3} kg.m{sup -1}.s{sup -1}, the one-dimensional model is sufficient; if it is included in the interval (10{sup -3} kg.m{sup -1}.s{sup -1}, 10{sup -2} kg.m{sup -1}.s{sup -1}), the partially two-dimensional model is useful; if it is superior to 10{sup -2} kg.m{sup -1}.s{sup -1}, it is necessary to use the two-dimensional model. Generally, whatever the thermal conditions on the plate are, heat transfer is dominated by the liquid-vapor transition. (authors)

  17. Electron-gun Evaporation of Cu and In thin films as Precursors for CuInSe{sub 2} Formation; Evaporacion mediante Canon de Electrones de Laminas Delgadas de Cu e In como Precursores para la Obtencion de CuInSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Caballero, R.; Guillen, C.

    2001-07-01

    In the present investigation CuInSe{sub 2} is obtained in two stages: sequential evaporation of Cu and In using an electron gun evaporator on substrates up to 30 x 30 cm''2, and a posterior selenization of the deposited films. The study is mainly focused on the first stage, in where the control of the different evaporation parameters of the metal precursors is essential. Electrical measurements are carried out, and also the topography and the thickness are determined with the object of studying the properties and homogeneity of the thin films. (Author) 19 refs.

  18. Self-floating carbon nanotube membrane on macroporous silica substrate for highly efficient solar-driven interfacial water evaporation

    KAUST Repository

    Wang, Yuchao

    2016-01-22

    Given the emerging energy and water challenges facing the mankind, solar-driven water evaporation has been gaining renewed research attention from both academia and industry as an energy efficient means of wastewater treatment and clean water production. In this project, a bi-layered material, consisting of a top self-floating hydrophobic CNT membrane and a bottom hydrophilic macroporous silica substrate, was rationally designed and fabricated for highly energy-efficient solar driven water evaporation based on the concept of interfacial heating. The top thin CNT membrane with excellent light adsorption capability, acted as photothermal component, which harvested and converted almost the entire incident light to heat for exclusively heating of interfacial water. On the other hand, the macroporous silica substrate provided multi-functions toward further improvement of operation stability and water evaporation performance of the material, including water pumping, mechanical support and heat barriers. The silica substrate was conducive in forming the rough surface structures of the CNT top layers during vacuum filtration and thus indirectly contributed to high light adsorption by the top CNT layers. With optimized thicknesses of the CNT top layer and silica substrate, a solar thermal conversion efficiency of 82 % was achieved in this study. The bi-layered material also showed great performance toward water evaporation from seawater and contaminated water, realizing the separation of water from pollutants, and indicating its application versatility.

  19. 竖管内溴化锂溶液降膜蒸发数值研究%NUMBERICAL RESEARCH OF FALLING FILM EVAPORATION OF LITHIUM BROMIDE SOLUTION IN VERTICAL TUBE

    Institute of Scientific and Technical Information of China (English)

    杨颖; 王洋; 石程名; 徐灿君

    2012-01-01

    The heat transfer performance of falling film evaporating LiBr solution in-vertical tube was investigated,which was directly driven by hot air from solar collector.Based on the coupled models of heat transfer and mass transfer,the numerical method of falling film evaporation of lithium bromide solution in vertical tube was presented.Using reasonable mathematical solution and MATLAB,the concentration and temperature distributions were calculated,the heat transfer coefficient was weaken with the increasing of inlet Re number,but the mass transfer coefficient was enhanced,and dimensionless relation of falling film evaporation was obtained.The compared results show that mass transfer will restrain heat transfer in falling film,and the affection can't be neglected.%研究以太阳集热板制取的高温空气为热源,直接驱动竖管内溴化锂溶液降膜蒸发的传热性能.提出适用于竖管内溴化锂溶液降膜蒸发传热传质耦合的数学模型,根据合理的数值解法,运用MATLAB软件编程,计算出降膜区域内温度场和浓度场,入口Re数越大,换热效果相对降低,而传质效果增强,并得到量纲为1的降膜换热准则式.通过与经验公式对比发现,溴化锂溶液中传质对传热有抑制作用,且其影响不可忽略.

  20. Analysis of the sintering stresses and shape distortion produced in co-firing of CGO-LSM/CGO bi-layer porous structures

    DEFF Research Database (Denmark)

    Ni, De Wei; Esposito, Vincenzo; Schmidt, Cristine Grings; Tadesse Molla, Tesfaye; Andersen, Kjeld Bøhm; Kaiser, Andreas; Ramousse, Severine; Pryds, Nini

    electrochemical flue gas purification devices, multilayer structures with alternating porous layers of CGO and a LSM/CGO mixture are used to achieve specific functional requirements. In a manufacturing process of such ceramic multilayer devices, co-firing is one of the critical steps as many defects such as......Gadolinium-doped cerium oxide (CGO) and lanthanum strontium manganate (LSM) are electro-ceramics materials with high potential for several electrochemical applications such as solid Oxide Fuel Cell (SOFC), gas separation membranes, and flue gas purification devices. Especially for novel...... cracks, de-lamination and shape distortion can result as a consequence of sintering mismatch stresses caused by the strain rate difference between layers. This work seeks to understand the underlying mechanisms that occur during the co-firing of porous CGO-LSM/CGO bi-layer laminates, by evaluating the...

  1. Schottky barrier contrasts in single and bi-layer graphene contacts for MoS{sub 2} field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Du, Hyewon; Kim, Taekwang; Shin, Somyeong; Kim, Dahye; Seo, Sunae, E-mail: sunaeseo@sejong.ac.kr [Department of Physics, Sejong University, Seoul 143-747 (Korea, Republic of); Kim, Hakseong; Lee, Sang Wook [Divison of Quantum Phases and Devices, Department of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of); Sung, Ji Ho; Jo, Moon-Ho [Center for Artificial Low-Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Lee, Myoung Jae [Center for Artificial Low-Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Seo, David H. [Samsung Electronics Company, Limited, System LSI Division, TD Team, Gyunggi 446-711 (Korea, Republic of)

    2015-12-07

    We have investigated single- and bi-layer graphene as source-drain electrodes for n-type MoS{sub 2} transistors. Ti-MoS{sub 2}-graphene heterojunction transistors using both single-layer MoS{sub 2} (1M) and 4-layer MoS{sub 2} (4M) were fabricated in order to compare graphene electrodes with commonly used Ti electrodes. MoS{sub 2}-graphene Schottky barrier provided electron injection efficiency up to 130 times higher in the subthreshold regime when compared with MoS{sub 2}-Ti, which resulted in V{sub DS} polarity dependence of device parameters such as threshold voltage (V{sub TH}) and subthreshold swing (SS). Comparing single-layer graphene (SG) with bi-layer graphene (BG) in 4M devices, SG electrodes exhibited enhanced device performance with higher on/off ratio and increased field-effect mobility (μ{sub FE}) due to more sensitive Fermi level shift by gate voltage. Meanwhile, in the strongly accumulated regime, we observed opposing behavior depending on MoS{sub 2} thickness for both SG and BG contacts. Differential conductance (σ{sub d}) of 1M increases with V{sub DS} irrespective of V{sub DS} polarity, while σ{sub d} of 4M ceases monotonic growth at positive V{sub DS} values transitioning to ohmic-like contact formation. Nevertheless, the low absolute value of σ{sub d} saturation of the 4M-graphene junction demonstrates that graphene electrode could be unfavorable for high current carrying transistors.

  2. SHEAR BOND STRENGTHS BETWEEN CERAMIC CORES AND VENEERING CERAMICS OF DENTAL BI-LAYERED CERAMIC SYSTEMS AND THE SENSITIVITY TO THERMOCYCLING

    Directory of Open Access Journals (Sweden)

    SUN TING, BDS, DDS

    2012-09-01

    Full Text Available The purpose of this study was to investigate the bond strength between various commercial ceramic core materials and veneering ceramics of dental bi-layered ceramic combinations and the effect of thermocycling. The shear bond strength of four dental bi-layered ceramic combinations (white Cercon, yellow Cercon, white Lava, yellow Lava, IPS E.max were tested. Metal ceramic combinations were conducted as a control group. Half of each group was subjected to thermocycling. All specimens were thereafter subjected to a shear force. The initial mean shear bond strength values in MPa ± S.D were 28.02 ± 3.04 for White Cercon Base/Cercon Ceram Kiss, 27.54 ± 2.20 for Yellow Cercon Base/Cercon Ceram Kiss, 28.43 ± 2.13for White Lava Frame/Lava Ceram, 27.36 ± 2.25 for Yellow Lava Frame/Lava Ceram, 47.10 ± 3.77 for IPS E.max Press/IPS E.max Ceram and 30.11 ± 2.15 for metal ceramic control. The highest shear strength was recorded for IPS E.max Press/IPS E.max Ceram before and after thermocycling. The mean shear bond strength values of five other combinations were not significantly different (P < 0.05. Lithium-disilicate based combinations produced the highest core-veneer bonds that overwhelmed the metal ceramic combinations. Thermocycling had no effect on the core-veneer bonds. The core-veneer bonds of zirconia based combinations were not weakened by the addition of coloring pigments.

  3. Temperature studies of optical parameters of (Ag3AsS3)0.6(As2S3)0.4 thin films prepared by rapid thermal evaporation and pulse laser deposition

    Science.gov (United States)

    Studenyak, I. P.; Kutsyk, M. M.; Buchuk, M. Yu.; Rati, Y. Y.; Neimet, Yu. Yu.; Izai, V. Yu.; Kökényesi, S.; Nemec, P.

    2016-02-01

    (Ag3AsS3)0.6(As2S3)0.4 thin films were deposited using rapid thermal evaporation (RTE) and pulse laser deposition (PLD) techniques. Ag-enriched micrometre-sized cones (RTE) and bubbles (PLD) were observed on the thin film surface. Optical transmission spectra of the thin films were studied in the temperature range 77-300 K. The Urbach behaviour of the optical absorption edge in the thin films due to strong electron-phonon interaction was observed, the main parameters of the Urbach absorption edge were determined. Temperature dependences of the energy position of the exponential absorption edge and the Urbach energy are well described in the Einstein model. Dispersion and temperature dependences of refractive indices were analysed; a non-linear increase of the refractive indices with temperature was revealed. Disordering processes in the thin films were studied and compared with bulk composites, the differences between the thin films prepared by RTE and PLD were analysed.

  4. Plasma-Enhanced Chemical Vapor Deposition (PE-CVD) yields better Hydrolytical Stability of Biocompatible SiOx Thin Films on Implant Alumina Ceramics compared to Rapid Thermal Evaporation Physical Vapor Deposition (PVD).

    Science.gov (United States)

    Böke, Frederik; Giner, Ignacio; Keller, Adrian; Grundmeier, Guido; Fischer, Horst

    2016-07-20

    Densely sintered aluminum oxide (α-Al2O3) is chemically and biologically inert. To improve the interaction with biomolecules and cells, its surface has to be modified prior to use in biomedical applications. In this study, we compared two deposition techniques for adhesion promoting SiOx films to facilitate the coupling of stable organosilane monolayers on monolithic α-alumina; physical vapor deposition (PVD) by thermal evaporation and plasma enhanced chemical vapor deposition (PE-CVD). We also investigated the influence of etching on the formation of silanol surface groups using hydrogen peroxide and sulfuric acid solutions. The film characteristics, that is, surface morphology and surface chemistry, as well as the film stability and its adhesion properties under accelerated aging conditions were characterized by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and tensile strength tests. Differences in surface functionalization were investigated via two model organosilanes as well as the cell-cytotoxicity and viability on murine fibroblasts and human mesenchymal stromal cells (hMSC). We found that both SiOx interfaces did not affect the cell viability of both cell types. No significant differences between both films with regard to their interfacial tensile strength were detected, although failure mode analyses revealed a higher interfacial stability of the PE-CVD films compared to the PVD films. Twenty-eight day exposure to simulated body fluid (SBF) at 37 °C revealed a partial delamination of the thermally deposited PVD films whereas the PE-CVD films stayed largely intact. SiOx layers deposited by both PVD and PE-CVD may thus serve as viable adhesion-promoters for subsequent organosilane coupling agent binding to α-alumina. However, PE-CVD appears to be favorable for long-term direct film exposure to aqueous

  5. Use of a thin-film evaporator for bitumen coating of radioactive concentrates; Utilisation d'un evaporateur a couche mince pour l'enrobage par le bitume de concentrats radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Lefillatre, G.; Rodier, J.; Hullo, R.; Cudel, Y.; Rodi, L. [Commissariat a l' Energie Atomique, Chusclan (France). Centre de Production de Plutonium de Marcoule

    1969-07-01

    Following the development in the laboratory of a process for coating evaporation concentrates with bitumen, a technological study of this coating process has been undertaken. The report describes a pilot installation for the bitumen coating of concentrates, which uses a thin-film evaporator LUWA L 150. The first, inactive series of tests was designed to determine the maximum and optimum capacities of the evaporator by varying the amounts of bitumen and of concentrate, the rotor speed and the thermo-fluid temperature. Two rotors were tested, one of conventional type, the other a model especially designed for high viscosity products. The maximum capacity of evaporation of the apparatus is 72 kg/hr for a heating temperature of 221 deg. C. During normal operation, the evaporator can produce 50 kg/hr of coated product containing 55 to 60 per cent of bitumen (Mexphalte 40/50), the water content of the product remaining under 0.5 per cent. A second series of tests will shortly be carried out on this pilot installation using, in particular, bituminous emulsions containing mainly Mexphalte 40/50 and 80/100. (authors) [French] A la suite de la mise au point en laboratoire d'un procede d'enrobage par le bitume de concentrats d'evaporation, une etude technologique de cet enrobage a ete entreprise. Ce rapport decrit une installation pilote d'enrobage par le bitume de concentrats utilisant un evaporateur a couche mince LUWA L 150. La premiere serie d'essais en inactif a eu pour but de definir les capacites maximales et optimales de l'evaporateur en faisant varier les dosages en bitume et en concentrats, la vitesse du rotor et la temperature du thermo-fluide. Deux rotors ont ete testes, l'un de type classique, l'autre d'un modele special concu pour les produits de haute viscosite. La capacite d'evaporation maximale de l'appareil est de 72 kg/h d'eau pour une temperature de chauffage de 221 deg. C. En marche normale l

  6. Annealing effects on the structural and electrical transport properties of n-type Bi2Te2.7Se0.3 thin films deposited by flash evaporation

    International Nuclear Information System (INIS)

    N-type Bi2Te2.7Se0.3 thermoelectric thin films with thickness 800 nm have been deposited on glass substrates by flash evaporation method at 473 K. Annealing effects on the thermoelectric properties of Bi2Te2.7Se0.3 thin films were examined in the temperature range 373-573 K. The structures, morphology and chemical composition of the thin films were characterized by X-ray diffraction, field emission scanning electron microscope and energy dispersive X-ray spectroscopy, respectively. Thermoelectric properties of the thin films have been evaluated by measurements of the electrical resistivity and Seebeck coefficient at 300 K. The Hall coefficients were measured at room temperature by the Van der Pauw method. The carrier concentration and mobility were calculated from the Hall coefficient. The films thickness of the annealed samples was measured by ellipsometer. When annealed at 473 K, the electrical resistivity and Seebeck coefficient are 2.7 mΩ cm and -180 μV/K, respectively. The maximum of thermoelectric power factor is enhanced to 12 μW/cm K2.

  7. Electrical and optical properties of thermally-evaporated thin films from A{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}] (A = K, PPh{sub 4}) and 1,8-dihydroxyanthraquinone

    Energy Technology Data Exchange (ETDEWEB)

    Carbia-Ruelas, E. [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico); Sanchez-Vergara, M.E., E-mail: elena.sanchez@anahuac.mx [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico); Garcia-Montalvo, V. [Instituto de Quimica, Universidad Nacional Autonoma de Mexico. Circuito Exterior, Ciudad Universitaria, 04510, Mexico, D. F (Mexico); Morales-Saavedra, O.G. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, CCADET-UNAM. A. P. 70-186, Coyoacan, 04510, Mexico, D. F (Mexico); Alvarez-Bada, J.R. [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico)

    2011-02-01

    In this work, the synthesis of molecular materials formed from A{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}] (A = K, PPh4) and 1,8 dihydroxyanthraquinone is reported. The synthesized materials were characterized by atomic force microscopy (AFM), infrared (IR) and ultraviolet-visible (UV-vis) spectroscopy. IR spectroscopy showed that the molecular-material thin-films, deposited by vacuum thermal evaporation, exhibit the same intra-molecular vibration modes as the starting powders, which suggests that the thermal evaporation process does not alter the initial chemical structures. Electrical transport properties were studied by dc conductivity measurements. The electrical activation energies of the complexes, which were in the range of 0.003-1.16 eV, were calculated from Arrhenius plots. Optical absorption studies in the wavelength range of 190-1090 nm at room temperature showed that the optical band gaps of the thin films were around 1.9-2.3 eV for direct transitions Eg{sub d}. The cubic NLO effects were substantially enhanced for materials synthesized from K{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}], where {chi}{sup (3)} (-3{omega}; {omega}, {omega}, {omega}) values in the promising range of 10{sup -12} esu have been evaluated.

  8. 地铁站全膜流板式蒸发冷却器设置位置分析%Installation location of intact film plate evaporative cooler in underground railway stations

    Institute of Scientific and Technical Information of China (English)

    蒋斌; 付祥钊; 王勇

    2011-01-01

    将板式换热器与蒸发冷却技术相结合,提出采用全膜流板式蒸发冷却器代替冷却塔,解决冷却塔难以设置的问题.对该设备在气液顺流、逆流、叉流条件下的传热性能进行模拟计算,结果表明,叉流条件下局部Nu最大,其次为顺流,逆流最小.通过对计算结果和安装运行的综合分析,提出地铁排风道水平段为全膜流板式蒸发冷却器的最佳设置方案,为该设备的实际应用提供了参考依据.%By applying plate heat exchanger and evaporative cooling technology, presents to substitute the intact film plate evaporative cooler for the cooling tower. Simulates the heat transfer performances of the device on conditions of concurrent flow, counter flow and cross flow. The results show a maximum local Nusselt number on cross flow condition, followed by concurrent flow, and a minimum on counter flow condition. By the comprehensive analysis of simulation results and installation and operation, recommends horizontal segment of extraction air duct in an underground railway station be the optimal location of installing the intact film plate evaporative cooler, providing reference for practical application.

  9. Fluorescence and optical properties of Er.sup.3+./sup. doped LaF.sub.3./sub. films fabricated by Electron Beam Evaporation and Pulsed Laser Deposition

    Czech Academy of Sciences Publication Activity Database

    Lančok, Ján; Novotný, Michal; Bulíř, Jiří; Fitl, Přemysl; Pokorný, Petr; Bočan, Jiří; Munoz, D.; Gonzalo, J.; Afonso, C.N.; Moine, B.

    Strasbourg: EMRS, 2010. 3 16/1. [E- MRS - Strasbourg - 2010 K: Rare earth doped materials for optical based technologies. 07.06.2010-11.06.2010, Strasbourg] R&D Projects: GA AV ČR IAA100100729 Institutional research plan: CEZ:AV0Z10100522 Keywords : Electron Beam Evaporation * Fluoride LaF 3 * fluorescence Subject RIV: BH - Optics, Masers, Lasers

  10. Preparation and microstructural characterization of TiC and Ti0.6W0.4/TiC0.6 composite thin films obtained by activated reactive evaporation

    International Nuclear Information System (INIS)

    Titanium carbide-based coatings were deposited on W substrates at a high coating growth rate by activated reactive evaporation at 500 and 600 deg. C in a L560 Leybold system using propene as reactive atmosphere. The crystal structure, lattice parameter, preferred orientation, and grain size of the coatings were determined by x-ray diffraction technique using Cu Kα. The analysis of the coating morphology was performed by scanning electron microscopy (SEM), and the composition of the films was analyzed by Auger electron spectroscopy and electron-probe microanalysis. Experimental results suggested that temperature was one of the most important parameters in the fabrication of stoichiometric TiC coatings. Thus, TiC coatings were obtained at 600 deg. C, whereas TiC0.6 nonstoichiometric coatings codeposited with a free Ti phase were obtained at 500 deg. C, giving rise to the formation of a composite thin film. After annealing at 1000 deg. C, the stoichiometric films remained stable, but a crack pattern was formed over the entire coating surface. In addition, Ti0.6W0.4/TiC0.6 composite thin coatings were obtained for the films synthesized at 500 deg. C. The formation of a Ti0.6W0.4 ductile phase in the presence of a TiC0.6 phase was responsible to avoid the coating cracking

  11. Properties of YBaCuO superconducting thin films deposited by nitrogen laser evaporation and heat-treated in O2 atmosphere by CW Co2-laser

    International Nuclear Information System (INIS)

    One of successfully applied methods for obtaining high Tc superconducting thin films is the pulsed laser deposition. The advantage of this method is preserving the film stoichiometry in comparison to target if UV eximer lasers, and for Nd-YAG laser in Q-modulation mode are used. In order to obtain the orthorombic phase of YBa2Cu3O7-x, the films are annealed in O2 atmosphere during the deposition process and after that. One problem her is the substrate temperature control. This temperature (Ts) determines to a great extent the vapor condensation mechanism and the chemical-physical processes at the substrate-film interface. This paper describes a method of obtaining high Tc superconducting thin films of YBa2Cu3O7-x by means of an N2 pulse laser and the properties of received films. The substrates used were poly-Al2O3, sapphire, SrTiO3 and Si

  12. Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas y Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F.; Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati (Roma) (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-02-26

    A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

  13. Dielectric relaxation dependent memory elements in pentacene/[6,6]-phenyl-C61-butyric acid methyl ester bi-layer field effect transistors

    International Nuclear Information System (INIS)

    We fabricate a pentacene/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bi-layer field effect transistor (FET) featuring large hysteresis that can be used as memory elements. Intentional introduction of excess electron traps in a PCBM layer by exposure to air caused large hysteresis in the FET. The memory window, characterized by the threshold voltage difference, increased upon exposure to air and this is attributed to an increase in the number of electron trapping centers and (or) an increase in the dielectric relaxation time in the underlying PCBM layer. Decrease in the electron conduction in the PCBM close to the SiO2 gate dielectric upon exposure to air is consistent with the increase in the dielectric relaxation time, ensuring that the presence of large hysteresis in the FET originates from electron trapping at the PCBM not at the pentacene. - Highlights: • Charge trapping-induced memory effect was clarified using transistors. • The memory window can be enhanced by controlling charge trapping mechanism. • Memory transistors can be optimized by controlling dielectric relaxation time

  14. Analysis of bi-layer oxide on austenitic stainless steel, 316L, exposed to Lead–Bismuth Eutectic (LBE) by X-ray Photoelectron Spectroscopy (XPS)

    Energy Technology Data Exchange (ETDEWEB)

    Koury, D., E-mail: dan@physics.unlv.edu [Dept. of Physics and Astronomy, MS 4002, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 (United States); Johnson, A.L. [Harry Reid Center, MS 4009, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 (United States); Ho, T. [Dept. of Chemistry, MS 4002, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 (United States); Farley, J.W. [Dept. of Physics and Astronomy, MS 4002, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 (United States)

    2013-09-15

    Corrosion of the austenitic stainless steel alloy 316L by Lead–Bismuth Eutectic (LBE) was studied using X-ray Photoelectron Spectroscopy (XPS) with Sputter-Depth Profiling (SDP), and compared to data taken by Scanning Electron Microscopy (SEM) and Energy Dispersive X-rays (EDXs). Exposed and unexposed samples were compared. Annealed 316L samples, exposed to LBE for durations of 1000, 2000 and 3000 h, developed bi-layer oxides up to 30 μm thick. Analysis of the charge-states of the 2p{sub 3/2} peaks of iron, chromium, and nickel in the oxide layers reveal an inner layer consisting of iron and chromium oxides (likely spinel-structured) and an outer layer consisting of iron oxides (Fe{sub 3}O{sub 4}). Cold-rolled 316L samples, exposed for the same durations, form a chromium-rich, thin (⩽1 μm) oxide with some oxidized iron in the outermost ∼200 nm of the oxide layer. This is the first experiment to investigate what components of the 316L are oxidized by LBE exposure. It is shown here that nickel is metallic in the inner layer.

  15. Development of a 'bi-layer lift-off' method for high flow rate and high frequency Nitinol MEMS valve fabrication

    International Nuclear Information System (INIS)

    This paper presents modeling, fabrication and testing results for a high flow rate and high frequency nickel titanium alloy (Nitinol) MEMS valve. ANSYS® is used to evaluate several Nitinol MEMS valve structural designs with the conclusion that a pentagonal flap with five legs produces higher frequencies and higher strengths without the inherent rotation problem present in four-leg designs. The Nitinol penta-leg design was fabricated using a novel bi-layer lift-off method. A polymethylglutarimide (PMGI) polymer layer is initially used as an underlayer while a chromium layer is used as a top layer to produce a non-rotational ortho-planar Nitinol MEMS valve array without the problems inherent in conventional Nitinol wet etching. The array consists of 65 microvalves with a single valve having dimensions of 1 mm circumference, 50 µm leg width and 8.2 µm Nitinol thickness. Each microvalve covers an orifice of 220 µm diameter and 500 µm in length and is capable of producing 150 µm vertical deflection. The Nitinol MEMS valve array was tested for flow rates in a hydraulic system as a function of applied pressure with a maximum water flow rate of 16.44 cc s−1

  16. The influence of thermal annealing on residual stresses and mechanical properties of arc-evaporated TiCxN1-x (x=0, 0.15 and 0.45) thin films

    International Nuclear Information System (INIS)

    We report the stress relaxation behavior of arc-evaporated TiCxN1-x thin films during isothermal annealing between 350 and 900 deg. C. Films with x=0, 0.15, and 0.45, each having an initial compressive intrinsic stress σint=-5.4 GPa, were deposited by varying the substrate bias Vs and the gas composition. Annealing above the deposition temperature leads to a steep decrease in the magnitude of σint to a saturation stress value, which is a function of the annealing temperature. The corresponding apparent activation energies for stress relaxation are Ea=2.4, 2.9, and 3.1 eV, for x=0, 0.15, and 0.45, respectively. TiC0.45N0.55 films with a lower initial stress σint=-3 GPa, obtained using a high substrate bias, show a higher activation energy Ea=4.2 eV. In all the films, stress relaxation is accompanied by a decrease in defect density indicated by the decreased width of X-ray diffraction peaks and decreased strain contrast in transmission electron micrographs. Correlation of these results with film hardness and microstructure measurements indicates that the stress relaxation is a result of point-defect annihilation taking place both during short-lived metal-ion surface collision cascades during deposition, and during post-deposition annealing by thermally activated processes. The difference in Ea for the films of the same composition deposited at different Vs suggests the existence of different types of point-defect configurations and recombination mechanisms

  17. CdxTe薄膜的共蒸发法制备及其表征%Preparation and Characterization of CdxTe Thin Films Deposited by Co-evaporation

    Institute of Scientific and Technical Information of China (English)

    束青; 武莉莉; 冯良桓; 王文武; 曹五星; 张静全; 李卫; 黎兵

    2015-01-01

    CdxTe thin films with differentx values were deposited for the first time through controlling evaporation rates of CdTe and Te powder by vacuum co-evaporation. Then the films were annealed in N2atmosphere at 185℃. The morphological, structural, optical, and electrical properties of the CdxTe films were investigated by X ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectrum and temperature dependence of the dark conductivity. UV-visible absorption spectrum demonstrates that energy band gaps (Eg) of different CdxTe films change from 0.99 eV to 1.46 eV. The absorption edges of different CdxTe films move towards longer wavelength and their transmittances reduce dramatically as thex value decreases from 0.8 to 0.2. XRD shows that as-deposited CdxTe thin films are amorphous when value ofx is less than 0.6. Otherwise, CdxTe thin films are crystalline whose CdTe phase with preferential in (111) direction while value ofx is approaching 1. The result indicates that annealing treatment is helpful for the films shifting from amorphous to polycrystalline. All the films exhibit p-type conductivity and the con-ductivity increases firstly as temperature rises. But it becomes abnormal while the temperature reaches a certain point. Data from this research suggest that CdxTe thin films can potentially be used for CdTe thin film solar cells to improve the long wavelength response.%采用CdTe和Te双源共蒸发的方法,调控CdTe和Te源的蒸发速率,首次制备出一系列不同x组分的CdxTe二元化合物薄膜,并在N2气气氛下进行185℃退火处理。通过XRD、SEM、紫外–可见吸收光谱分析及暗电导率–温度关系对CdxTe薄膜的结构、形貌、光学和电学性质进行表征。紫外–可见吸收光谱分析表明,不同x组分的CdxTe薄膜,其禁带宽度可在0.99~1.46 eV之间变化,随着x值从0.8减小到0.2,吸收边向长波方向移动,而且透过率也显著下降。XRD结果表明, x值小于0

  18. Preparation and optical and electrical evaluation of bulk SiO2 sonogel hybrid composites and vacuum thermal evaporated thin films prepared from molecular materials derived from (Fe, Co) metallic phthalocyanines and 1,8 dihydroxiantraquinone compounds

    International Nuclear Information System (INIS)

    Semiconducting molecular material of PcFe(CN)L1 and PcCo(CN)L1 (L1 = 1,8 dihydroxianthraquinone), PcFe(CN)L2 and PcCo(CN)L2 (L2 = double potassium salt of 1,8 dihydroxianthraquinone) have been successfully used to prepare thin film and bulk sol-gel hybrid optical materials. These samples were developed according to the vacuum thermal evaporation technique and the catalyst-free sonogel route, respectively. Thin films samples were deposited on Corning glass substrates and crystalline silicon wafers and were characterized by infrared (FTIR), Raman and ultraviolet-visible (UV-vis) spectroscopies. IR-spectroscopy and Raman studies unambiguously confirmed that the molecular material thin films exhibit the same intra-molecular bonds, which suggests that the thermal evaporation process does not alter these bonds significantly. These results show that it is possible to deposit molecular materials of PcFe(CN)L2 and PcCo(CN)L2 on Corning glass substrates and silicon wafers. From the UV-vis studies the optical band gap (Eg) was evaluated. The effect of temperature on conductivity was also evaluated in these samples. Finally, the studied molecular systems dissolved at different concentrations in tetrahydrofuran (THF) were successfully embedded into a highly pure SiO2 sonogel network generated via sonochemical reactions to form several solid state, optically active sol-gel hybrid glasses. By this method, homogeneous and stable hybrid monoliths suitable for optical characterization can be produced. The linear optical properties of these amorphous bulk structures were determined by the Brewster angle method and by absorption-, Raman- and photoluminescent (PL)-spectroscopies, respectively

  19. Preparation and optical and electrical evaluation of bulk SiO{sub 2} sonogel hybrid composites and vacuum thermal evaporated thin films prepared from molecular materials derived from (Fe, Co) metallic phthalocyanines and 1,8 dihydroxiantraquinone compounds

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Vergara, Maria Elena [Coordinacion de Ingenieria Mecatronica, Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786 Huixquilucan, Estado de Mexico (Mexico); Morales-Saavedra, Omar G. [Universidad Nacional Autonoma de Mexico, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, CCADET-UNAM, A.P. 70-186, Coyoacan, 04510 Mexico, D.F. (Mexico)], E-mail: omar.morales@ccadet.unam.mx; Ontiveros-Barrera, Fernando G.; Torres-Zuniga, Vicente; Ortega-Martinez, Roberto [Universidad Nacional Autonoma de Mexico, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, CCADET-UNAM, A.P. 70-186, Coyoacan, 04510 Mexico, D.F. (Mexico); Ortiz Rebollo, Armando [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Materiales, IIM-UNAM, A.P. 70-360, Coyoacan, 04510 Mexico, D.F. (Mexico)

    2009-02-25

    Semiconducting molecular material of PcFe(CN)L1 and PcCo(CN)L1 (L1 = 1,8 dihydroxianthraquinone), PcFe(CN)L2 and PcCo(CN)L2 (L2 = double potassium salt of 1,8 dihydroxianthraquinone) have been successfully used to prepare thin film and bulk sol-gel hybrid optical materials. These samples were developed according to the vacuum thermal evaporation technique and the catalyst-free sonogel route, respectively. Thin films samples were deposited on Corning glass substrates and crystalline silicon wafers and were characterized by infrared (FTIR), Raman and ultraviolet-visible (UV-vis) spectroscopies. IR-spectroscopy and Raman studies unambiguously confirmed that the molecular material thin films exhibit the same intra-molecular bonds, which suggests that the thermal evaporation process does not alter these bonds significantly. These results show that it is possible to deposit molecular materials of PcFe(CN)L2 and PcCo(CN)L2 on Corning glass substrates and silicon wafers. From the UV-vis studies the optical band gap (E{sub g}) was evaluated. The effect of temperature on conductivity was also evaluated in these samples. Finally, the studied molecular systems dissolved at different concentrations in tetrahydrofuran (THF) were successfully embedded into a highly pure SiO{sub 2} sonogel network generated via sonochemical reactions to form several solid state, optically active sol-gel hybrid glasses. By this method, homogeneous and stable hybrid monoliths suitable for optical characterization can be produced. The linear optical properties of these amorphous bulk structures were determined by the Brewster angle method and by absorption-, Raman- and photoluminescent (PL)-spectroscopies, respectively.

  20. CFD analysis of evaporation cooling experimental tests

    International Nuclear Information System (INIS)

    Falling film evaporation cooling is investigated by a CFD (computational fluid dynamics) code. The experimental activity, carried out at the University of Pisa using the EFFE facility, is aimed to contribute to the understanding of the heat and mass transfer mechanisms involved in cooling of a metallic wall by evaporation of falling water films in a countercurrent air flow. This problem is relevant for innovative nuclear reactor containment. The mathematical model, the governing equations and the boundary conditions implemented in the code are briefly described; a detailed description of the method adopted to account for mass transfer and the presence of the film follows. Then, the calculated results are analysed and compared with experimental data, highlighting the improvement in the cooling capabilities obtained owing to evaporation with respect to the case of pure convection. (authors)