scispace - formally typeset
Search or ask a question

Showing papers on "Evaporation (deposition) published in 2007"


Journal ArticleDOI
TL;DR: The results indicated preparation method was the decisive factor rather than size and morphology in the final degradation efficiency of ZnO powders.

341 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used the matrix assisted pulsed laser evaporation (MAPLE) technique for the deposition of titania (TiO 2 ) nanoparticle thin films to be used for gas sensor applications.
Abstract: Matrix assisted pulsed laser evaporation (MAPLE) is a new promising laser-based technique thought for polymer or biomaterial thin films deposition. In this work, the MAPLE technique has been used for the deposition of titania (TiO 2 ) nanoparticle thin films to be used for gas sensor applications. For this purpose, an aqueous solution of TiO 2 nanoparticles, synthesized by a novel chemical route, was frozen at the liquid nitrogen temperature and introduced in a vacuum chamber to be irradiated with a pulsed ArF excimer laser. The volatile solvent was pumped away while the TiO 2 nanoparticles were deposited on Si and Al 2 O 3 substrates. A uniform distribution of TiO 2 nanoparticles with an average size of about 10 nm was obtained, as demonstrated by high resolution scanning electron microscopy (SEM-FEG) inspection. We realized gas-sensing devices based on resistive transduction mechanism by using the TiO 2 nanoparticles thin films deposited by the MAPLE technique onto suitable rough alumina substrates equipped with interdigitated electrical contacts (IDC) 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 were extracted and compared with to the corresponding parameters towards acetone.

162 citations


Journal ArticleDOI
TL;DR: In this article, the effects of the film deposition method, annealing temperature, film thickness, and patterning by photolithography are systematically investigated, and the effect of patterning on the performance of copper oxide nanowires was shown.
Abstract: Large-area and aligned copper oxide nanowires have been synthesized by thermal annealing of copper thin films deposited onto silicon substrate. The effects of the film deposition method, annealing temperature, film thickness, annealing gas, and patterning by photolithography are systematically investigated. Long and aligned nanowires can only be formed within a narrow temperature range from 400 to 500°C. Electroplated copper film is favourable for the nanowire growth, compared to that deposited by thermal evaporation. Annealing copper thin film in static air produces large-area, uniform, but not well vertically aligned nanowires along the thin film surface. Annealing copper thin film under a N2/O2 gas flow generates vertically aligned, but not very uniform nanowires on large areas. Patterning copper thin film by photolithography helps to synthesize large-area, uniform, and vertically aligned nanowires along the film surface. The copper thin film is converted into bicrystal CuO nanowires, Cu2O film, and also perhaps some CuO film after the thermal treatment in static air. Only CuO in the form of bicrystal nanowires and thin film is observed after the copper thin film is annealed under a N2/O2 gas flow.

139 citations


Journal ArticleDOI
TL;DR: P3e (TM) is a new approach in PVD technology for the deposition of metal oxides as mentioned in this paper, which is dedicated to the formation of alumina-based and other metallic oxide layers and comprises high current pulse technique for arc sources.
Abstract: Pulse enhanced electron emission (P3e (TM)) is a new approach in PVD technology for the deposition of metal oxides. The process is dedicated to the formation of alumina-based and other metallic oxide layers and comprises high current pulse technique for the arc sources. The method allows a deposition of hard alumina-based coatings at substrate temperatures below 600 degrees C. Different oxide layers and layer combinations were prepared with this new technique illustrating the enormous potential for the design of wear resistant coatings. The layers were characterized with respect to hardness, stress, composition, crystal structure, and thermal stability. Solid solutions of (Al1-xCrx)(2)O-3 could be synthesized for a composition range of 0.3 <= 5x

115 citations


Journal ArticleDOI
TL;DR: In this article, a thermal evaporation-deposition approach using microwave energy was employed for the fabrication of ZnO micro-and nano-structures, including microtubes, microrods, nanowires and nanobelts.

99 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigate and compare complementary approaches to SiNW production in terms of yield, morphology control, and electrical properties, and report concentrated and stable dispersions of SiNWs in solvents compatible with semiconducting organic polymers.
Abstract: We investigate and compare complementary approaches to SiNW production in terms of yield, morphology control, and electrical properties. Vapor-phase techniques are considered, including chemical vapor deposition (with or without the assistance of a plasma) and thermal evaporation. We report Au-catalyzed nucleation of SiNWs at temperatures as low as 300°C using SiH4 as precursor. We get yields up to several milligrams by metal-free condensation of SiO powders. For all processes, we control the final nanostructure morphology. We then report concentrated and stable dispersions of SiNWs in solvents compatible with semiconducting organic polymers. Finally, we investigate the electrical response of intrinsic SiNWs grown by different methods. All our SiNWs exhibit p-type behavior and comparable performance, though in some cases ambipolar devices are observed. Thus, processing and morphology, rather than the growth technique, are key to achieve optimal samples for applications.

90 citations


Journal ArticleDOI
TL;DR: In this paper, the formation of ZnO/carbon nanotubes heterostructures achieved by means of a thermal evaporation method was reported, and the main building block of the observed morphologies was the nanorod whose self-assembling resulted in various structures such as polypods and nano-hedgehogs.

88 citations


Journal ArticleDOI
TL;DR: Twinned zigzag SiC nanoneedles have been synthesized by silicon evaporation onto multiwall carbon nanotubes (MWCNTS) at 1500 °C for 8 h.
Abstract: Twinned zigzag SiC nanoneedles have been synthesized by silicon evaporation onto multiwall carbon nanotubes (MWCNTS) at 1500 °C for 8 h. The product was characterized by X-ray diffraction (XRD), fi...

88 citations


Journal ArticleDOI
TL;DR: In this paper, the photoelectrochemical responses of WO3 thin films have been investigated as a function of annealing temperature up to 600°C, and the results strongly suggest that the reduced amount of electrochemical reaction sites for the film annealed at 600 °C film plays a significant role in influencing the decreased photoresponse.
Abstract: The photoelectrochemical responses of WO3 thin films have been investigated as a function of annealing temperature up to 600 °C. WO3 films were deposited on unheated substrates by thermal evaporation followed by annealing at temperatures of 300, 500, and 600 °C for 5 h in air. The WO3 film annealed at 500 °C shows the best photoelectrochemical response due to improved crystallinity and enhanced light absorption in the long-wavelength region. Although the WO3 film annealed at 600 °C exhibits better crystallinity and increased light absorption properties, it shows a decreased photoelectrochemical response in comparison to the one annealed at 500 °C. These results strongly suggests that the reduced amount of electrochemical reaction sites for the film annealed at 600 °C film plays a significant role in influencing the decreased photoresponse.

86 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of pentacene crystalline domain size on performance was investigated by controlling the Pentacene deposition rate, which showed improved light-to-electricity conversion efficiencies from 0.49% to 1.12% under an AM 1.5 solar simulator (100mW/cm 2 ).

83 citations


Journal ArticleDOI
TL;DR: The influence of substrate temperature on the structural, surface morphological and optical properties of the films has been studied in this paper, where the films were deposited on glass and fluorine doped tin oxide (SnO 2 :F or FTO) coated glass substrates at different substrate temperatures like room temperature (RT, 30°C), 100°C and 200°C).

Journal ArticleDOI
TL;DR: In this article, thin-film deposition and photodecomposition of cesium azide are demonstrated and used to fill arrays of miniaturized atomic resonance cells with buffer gas for chip-scale atomic-based instruments.
Abstract: The thin-film deposition and photodecomposition of cesium azide are demonstrated and used to fill arrays of miniaturized atomic resonance cells with cesium and nitrogen buffer gas for chip-scale atomic-based instruments. Arrays of silicon cells are batch fabricated on wafers into which cesium azide is deposited by vacuum thermal evaporation. After vacuum sealing, the cells are irradiated with ultraviolet radiation, causing the azide to photodissociate into pure cesium and nitrogen in situ. This technology integrates the vapor-cell fabrication and filling procedures into one continuous and wafer-level parallel process, and results in cells that are optically transparent and chemically pure.

Journal ArticleDOI
TL;DR: In this article, electron beam evaporation of metal onto a monolayer of organic molecules can yield reproducible electrical contacts, if the sample is on a cooled substrate and the metal contact forms without damaging even the molecules' outermost groups.
Abstract: We show that electron beam evaporation of metal onto a monolayer of organic molecules can yield reproducible electrical contacts, if evaporation is indirect and the sample is on a cooled substrate. The metal contact forms without damaging even the molecules' outermost groups. In contrast, direct evaporation seriously damages the molecules. By comparing molecular effects on metal/molecular layer/GaAs junctions, prepared by indirect evaporation and by other soft contacting methods, we confirm experimentally that Au is not an optimal choice as an evaporated contact metal. We ascribe this to the ease by which Au can diffuse between molecules, something that can, apart from direct contact−substrate connections, lead to undesired and uncontrollable interfacial interactions. Such phenomena are largely absent with Pd as evaporated contact.

Journal ArticleDOI
TL;DR: In this article, an e-beam evaporation technique was used for the preparation of a multilayer ZnO-Al-doped (ZnO) multi-layer coatings on glass.

Journal ArticleDOI
31 Oct 2007-ACS Nano
TL;DR: One class of application of nanoskiving can fabricate complex nanostructures that are difficult or impossible to achieve by other methods of nanofabrication is illustrated: frequency-selective surfaces at mid-IR wavelengths.
Abstract: This paper describes the use of nanoskiving to fabricate complex metallic nanostructures by sectioning polymer slabs containing small, embedded metal structures. This method begins with the deposition of thin metallic films on an epoxy substrate by e-beam evaporation or sputtering. After embedding the thin metallic film in an epoxy matrix, sectioning (in a plane perpendicular or parallel to the metal film) with an ultramicrotome generates sections (which can be as thin as 50 nm) of epoxy containing metallic nanostructures. The cross-sectional dimensions of the metal wires embedded in the resulting thin epoxy sections are controlled by the thickness of the evaporated metal film (which can be as small as 20 nm) and the thickness of the sections cut by the ultramicrotome; this work uses a standard 45° diamond knife and routinely generates slabs 50 nm thick. The embedded nanostructures can be transferred to, and positioned on, planar or curved substrates by manipulating the thin polymer film. Removal of the e...

Journal ArticleDOI
TL;DR: In this article, the authors present a method for surface nanopatterning using chemical solution deposition (CSD) of molecular inorganic precursors and commercial block copolymers on bare or hydrophobised silicon wafer surfaces.
Abstract: TiO2, Al2O3, and ZrO2 patterns (or masks) composed of ordered nanomotifs of various morphologies (i.e., perforations (craters), rings, canyons, wires, dots, or channels) with typical lateral dimensions of <40 nm and thicknesses below 15 nm are presented. They were simply prepared by chemical solution deposition (CSD) of molecular inorganic precursors and commercial block copolymers on bare or hydrophobised silicon wafer surfaces. The various nanostructures are obtained by self-assembly during evaporation and are subsequently stabilized at 500 °C. Compared to other techniques for surface nanopatterning, the present method has the advantage of being cheap, reproducible, and easy to scale up and does not require specialized equipment. The type, dimension, and organization of these motifs were assessed by AFM, FE-SEM, spectroscopic ellipsometry, and GI-SAXS and are shown to depend on the conditions of preparation. We show that the critical parameters for controlling the nanopattern characteristics are the org...

Journal ArticleDOI
TL;DR: In this article, a layer of silver was deposited onto the surface of glass substrates, coated with AZO (Al-doped ZnO), to form Ag/AZO film structures, using e-beam evaporation techniques.

Journal ArticleDOI
TL;DR: In this article, a cathodic arc evaporation process operated in pure oxygen forms corundum-type micro-crystalline structures at temperatures below 600°C, showing no metal site splitting in the atomic structure.
Abstract: A novel cathodic arc evaporation process operated in pure oxygen forms corundum-type micro-crystalline structures at temperatures below 600°C. Thermally stable crystalline solid solutions of corundum-type (Al 1-xCrx)2Oy have been prepared with this method for x ≥ 0.3 at non-equilibrium conditions. The stability in (Al,Cr)2O3 phases can be explained by their degree of crystallinity and ordering within the structure. The applied processing method results in highly crystalline coatings of pure α-(Al1-xCr x)2Oy. With increasing fabrication temperature (maximum 600°), more stable phases are obtained showing no metal site splitting in the atomic structure. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA,.

Journal ArticleDOI
TL;DR: Tin selenide thin films were grown by flash evaporation method at substrate temperatures, TS=303-513 K at an interval of 30-K as discussed by the authors, and optical absorption studies indicated a direct band gap of 1.26 eV with high absorption coefficient (>104 cm−1) near the fundamental absorption edge.

Journal ArticleDOI
TL;DR: In this article, carbon-doped titanium oxide films (TiO x C y ) were deposited by an ion-assisted electron-beam evaporation system, using rutile TiO 2 powder as the source material and carbon monoxide flowing through an ion gun as the dopant source.

Journal ArticleDOI
TL;DR: In this article, the authors used X-ray diffraction to characterize the stress state and texture of TiAlN monolayer and TiN/TiAlN multilayer hard coatings deposited on WC-Co and tool steel substrates using the cathode arc evaporation method.
Abstract: Ex-situ X-ray diffraction was used to characterize the stress state and texture of TiAlN monolayer and TiN/TiAlN multilayer hard coatings deposited on WC–Co and tool steel substrates using the cathode arc evaporation method. For all coatings the compressive residual stress was found to be higher in the film deposited on tool steel than that deposited on WC–Co; this is due to the difference in the linear thermal expansion coefficient of the two substrates. X-ray diffraction polar scan measurements showed that the preferred orientation of the crystallites exhibits cylindrical symmetry but it is inclined with respect to the sample surface. Moreover, the inclination angle of the (002) diffracting planes increases with the increase of the residual stress in the coating. Different mechanisms that could explain the interdependence between fiber texture and residual stress are discussed.

Journal ArticleDOI
TL;DR: Tungsten oxide W18O49 nanowires with diameters of 10-20nm and lengths up to micrometers were synthesized with high yield by thermal evaporation in a tube furnace.
Abstract: Tungsten oxide W18O49 nanowires with diameters of 10–20nm were synthesized with high yield by thermal evaporation in a tube furnace. By heating tungsten trioxide powder at 900°C in vacuum (5×10−3torr), W18O49 nanowires with diameters of 10–20nm and lengths up to micrometers were produced with high yield on the Au-coated Si substrates located in the low temperature zone (550–600°C) of the furnace. The morphology, composition, and crystal structure of the nanowires were characterized by various methods. The conditions and the mechanism of W18O49 nanowire growth are discussed.

Journal ArticleDOI
Wei Chen1, Xiaodan Sun1, Qiang Cai1, Duan Weng1, Hengde Li1 
TL;DR: In this paper, a crack-free thick ordered mesoporous TiO2 films with excellent optical quality have been synthesized by combination of Doctor Blade technique and a two-step evaporation induced self-assembly (EISA) method.

Journal ArticleDOI
TL;DR: In this paper, the effect of the rate of deposition on the photoluminescence characteristics was also studied, which showed an increase in luminescence intensity with the decrease in the particle size.
Abstract: Nanocrystalline ZnS films have been grown on glass substrates by close spaced evaporation at various deposition rates, with a constant substrate temperature of 300 °C. The x-ray photoelectron spectroscopy studies revealed that nearly stoichiometric ZnS layers were grown at deposition rates in the range 20–30 A s−1. The x-ray diffraction data confirmed the cubic structure of ZnS films for all the deposition rates. The surface morphological studies were made using an atomic force microscope, which indicated a rough surface and that the roughness increases with the deposition rate. The optical analysis showed that the layers grown at a deposition rate of 30 A s−1 exhibited the highest optical transmittance of 82%. The optical band gap of the films varied in the range 3.63–3.54 eV with the change in the deposition rate. The effect of the rate of deposition on the photoluminescence characteristics was also studied, which showed an increase in luminescence intensity with the decrease in the particle size. The electrical properties of the layers were highly influenced by the deposition rate. The temperature dependence of electrical conductivity was measured and the activation energies were also evaluated.

Journal ArticleDOI
TL;DR: In this article, thin lysozyme films have been produced in a dry environment by MAPLE (matrix assisted pulsed laser evaporation) from a water ice matrix irradiated by laser light at 355nm above the absorption threshold of the protein.

Journal ArticleDOI
TL;DR: In this paper, a simple thermal evaporation of Zn powders, without using any catalysts, produces various ZnO nanostructures, such as nanobelts, nanorods, and nanowires.
Abstract: Various ZnO nanostructures, such as nanobelts, nanorods, and nanowires, have been grown on presynthesized SnO2 nanobelts via a simple thermal evaporation of Zn powders, without using any catalysts, producing various heterostructures. The evaporation temperature is the critical experimental parameter for the formation of different morphologies of these nanostructures. Room-temperature photoluminescence spectra of the heterostructures show that the relative intensity of ultraviolet emission to the green band can be tuned by controlling the morphologies and sizes of the secondary-grown 1D ZnO nanostructures, suggesting that the nano-heterostructures of these nanostructures grown on SnO2 nanobelts may have potential applications in nano-optoelectronic devices.

Journal ArticleDOI
TL;DR: In this paper, a modified electric arc-physical vapor deposition (EA-PVD) was used to obtain anatase-rich TiO2 thin coatings on various substrates.
Abstract: TiO2 thin coatings were prepared, on various substrates, through evaporation of metallic titanium in an oxidizing atmosphere by modified electric arc-physical vapor deposition (EA-PVD). The coatings were characterized chemically (by means of XPS and SIMS) and from the structural point of view (by means of XRD and Raman spectroscopy), in order to understand the factors which lead to homogeneous coatings with high anatase content. The type of substrate is the main parameter that influences the crystal structure of the coatings: when stainless steel is used as substrate the coatings consist essentially of rutile, while on glass substrates coatings containing mainly anatase are obtained. The photocatalytic activity of the samples upon UVA irradiation was tested by using phenol as the target molecule. Phenol in the solution can be photocatalytically and rapidly degraded through the EA-PVD anatase TiO2 coatings.

Journal ArticleDOI
01 Jan 2007-Carbon
TL;DR: The influence of a preliminary RF-plasma treatment of the multi wall carbon nanotube (MWCNTs) surface on the resulting overlayer morphology (dispersion, shape and size of metal clusters) formed by thermally evaporating Ag, Ni or Au atoms is studied in this article.

Journal ArticleDOI
TL;DR: In this article, a PVdF-HFP/PEG-PEGDMA cross-linking film has been prepared as the electrolyte for dye-sensitized solar cell (DSSC), which can be made porous by controlling evaporation behavior of solvents.

Journal ArticleDOI
TL;DR: In this paper, the micro-and nanostructures of Zn and ZnO with graphite were prepared by thermal evaporation and nanotetrapod growth.
Abstract: ZnO micro- and nanostructures were prepared by thermal evaporation of Zn and a mixture of ZnO with graphite. On heating Zn powder in a quartz tube at temperatures between 600 °C to 800 °C, radial growth of nanowires was observed on the source. On increasing the temperature to 900 °C, various interesting micro- and nanostructures of Zn and ZnO were observed to have deposited all over the quartz tube. On the other hand, when ZnO was heated in the presence of graphite, predominant growth of ZnO nanotetrapods was observed. Nanowires and tetrapods of ZnO were characterized by photoluminescence measurements and were found to show significantly improved response for detection of H2S gas at room temperature when compared with earlier studies. The response was seen to improve with increase in oxygen vacancies in the material.