Showing papers on "Evaporation (deposition) published in 1999"

Structure and strength of multilayers

Abstract: Nanometer-scale multilayer materials exhibit a wealth of interesting structural and mechanical property behaviors. Physical-vapor-deposition technology allows almost unlimited freedom to choose among elements, alloys, and Compounds as layering constituents and to design and produce materials with compositional and structural periodicities approaching the atomic Scale. These materials have tremendous interface area density, approaching 106 mm/mm3, so that a Square centimeter area of a one-micron-thick multilayer film with a bilayer period of 2 nm has an interface area of roughly 1,000 cm2. Hence interfacial effects can dominate multilayer structure and properties leading to unusually large strains and frequently stabilization of metastable structures. The atomic-scale layering of different materials also leads to very high hardnesses and good wear resistance. These materials are a test-bed for examination of the fundamental aspects of phase stability and for exploring mechanical strengthening mechanisms. They are also becoming increasingly interesting for applications such as hard coatings, x-ray optical elements, in microelectromechanical Systems (MEMS), and in magnetic recording media and heads.In this article, we review some of the interesting structures and mechanical properties that have been observed in nanometer-scale artificial multilayer structures.Superlattice thin films are readily deposited by vapor-phase techniques such as sputter deposition, evaporation, and chemical vapor deposition, as well as by electrochemical deposition. Superlattice deposition Systems are similar to conventional film deposition Systems, except for the provision to modulate the fluxes and thereby produce alternating super-lattice layers.

Fabrication of patterned media for high density magnetic storage

Abstract: Arrays of discrete, lithographically patterned magnetic elements have been proposed as a new generation of ultrahigh density patterned magnetic storage media. Interferometric lithography has been used to make prototype arrays over large areas with periods of 100–200 nm. Arrays of magnetic pillars, pyramids, and dots have been made by electrodeposition, evaporation and liftoff, and etching processes, and the magnetic properties of the particles and their mutual interactions have been measured.

Nanofabrication using a stencil mask

Abstract: We describe tests of a technique to fabricate nanostructures by the evaporation of metal through a stencil mask etched in a suspended silicon nitride membrane. Collimated evaporation through the mask gives metal dots less than 15 nm in diameter and lines 15–20 nm wide. We have investigated the extent of hole clogging and the factors which determine the ultimate resolution of the technique.

Spatial Extent of Lithium Intercalation in Anatase TiO2

Abstract: Thin smooth anatase TiO2 films are obtained by electron beam evaporation of reduced TiO2. These films show a preferential (004) orientation when deposited on electron beam evaporated amorphous titanium. Electrochemical lithium insertion into these films is studied with several optical and electrochemical techniques. A coloration efficiency of 13 cm2 C-1 is found, which is twice as high as that reported for TiO2 films grown by chemical vapor deposition (CVD). Potential-dependent capacitance measurements show that after the extraction of lithium ions has taken place a small region at the surface of the electrode has a much higher dielectric constant than that of the bulk of the electrode. This is explained by the presence of irreversibly trapped lithium ions in the region where a (reversible) phase transformation from anatase TiO2 to anatase Li0.5TiO2 has occurred. The extent of this region depends strongly on the intercalation potential; values of 7 and 17 nm are found after 2.5 h of intercalation at −1.0 ...

YBCO films on metal substrates with biaxially aligned MgO buffer layers

Abstract: We successfully deposited high quality YBCO films on metal tapes with biaxially aligned MgO buffer layers. e-gun evaporation on inclined substrates with a very high deposition rate of up to 250 nm/min was used for the deposition of the buffer layers. The MgO layers are biaxially textured with an in-plane full width at half maximum of 80. The MgO [001]-axis is not parallel to the substrate normal but tilted significantly towards the deposition direction. YBCO films were deposited on ISD buffer layers by reactive thermal co-evaporation. The critical current density of the films was found to be anisotropic due to the tilt of the [001]-axis. Critical current densities up to 7.9/spl times/10/sup 5/ A/cm/sup 2/ at 77 K were achieved.

Thin Film Microstructure Control Using Glancing Angle Deposition by Sputtering

Abstract: Thin films with microstructures controlled on a nanometer scale have been fabricated using a recently developed process called glancing angle deposition (GLAD) which combines oblique angle evaporation with controlled substrate motion. Critical to the production of GLAD thin films is the requirement for a narrow angular flux distribution centered at an oblique incidence angle. We report here recent work with low-pressure, long-throw sputter deposition with which we have succeeded in fabricating porous titanium thin films possessing “zig-zag,” helical, and “pillar” microstructures, demonstrating microstructural control on a level consistent with evaporated GLAD. The use of sputtering for GLAD simplifies process control and should enable deposition of a broader range of thin film materials.

Diamond/Ir/SrTiO3: A material combination for improved heteroepitaxial diamond films

Abstract: Heteroepitaxial diamond films with highly improved alignment have been realized by using the layer sequence diamond/Ir/SrTiO3(001). In a first step, epitaxial iridium films with a misorientation <0.2° have been deposited on polished SrTiO3(001) surfaces by electron-beam evaporation. Using the bias-enhanced nucleation procedure in microwave plasma chemical vapor deposition, epitaxial diamond grains with a density of 109 cm−2 could be nucleated on these substrates. The orientation relationship for this layer system is diamond(001)[100]∥Ir(001)[100]∥SrTiO3(001)[100]. The polar and azimuthal spread for the crystal orientation of a 600 nm thick diamond film is about 1° in each case. For an 8 μm thick diamond film a significantly improved alignment of 0.34° (polar) and 0.65° (azimuthal) has been measured. The latter values, which to the best of our knowledge are superior to those of all former reports about epitaxial diamond films on alternative substrates, indicate the high potential of the substrate Ir/SrTiO3...

GaN evaporation in molecular-beam epitaxy environment

Abstract: GaN(0001) thick layers were grown on c-plane sapphire substrates by molecular-beam epitaxy using NH3. The evaporation of such GaN layers in vacuum was studied as a function of substrate temperature. In situ laser reflectivity was used to quantitatively measure the decomposition rate of the GaN(0001) plane. It is nearly zero below 750 °C, increases rapidly above 800 °C, and reaches 1 μm/h at 850 °C. An activation energy of 3.6 eV is deduced for the thermal decomposition of GaN in vacuum. The evaporation rate as a function of the incident NH3 flux was also investigated for different substrate temperatures. A kinetic model is applied for the interpretation of the experimental results.

Growth of biaxially textured RE2O3 buffer layers on rolled-Ni substrates using reactive evaporation for HTS-coated conductors

Abstract: In an effort to develop alternative single buffer layer architectures for YBCO (YBa2Cu3O7-y) coated conductors, we have studied RE2O3 (RE = Y, and rare earths) as candidate materials. High-quality Y2O3, Gd2O3 and Yb2O3 buffer layers were grown epitaxially on biaxially textured Ni (100) substrates using reactive electron beam evaporation. Using thermodynamic considerations for the formation of metal oxides, we employed both reducing atmospheres and water vapour to oxidize the film in situ to form stoichiometric RE2O3. We have also prevented NiO formation at the substrate-film interface during this process. Detailed x-ray studies have shown that the Y2O3, Gd2O3 and Yb2O3 films were grown with a single epitaxial orientation. The lattice mismatch between YBCO and Gd2O3 was small as compared with that of YBCO with other rare earth oxides. SEM micrographs indicated that ~0.5 ?m thick Y2O3 films on rolled-Ni substrates were dense, continuous and crack free. A high Jc of 1.8 ? 106 A cm-2 at 77 K and self-field was obtained on YBCO films grown on alternative buffer layers with a layer sequence of YBCO/Yb2O3 (sputtered)/Y2O3 (e-beam)/Ni.

Thin film growth and band lineup of In2O3 on the layered semiconductor InSe

Abstract: Thin films of the transparent conducting oxide In2O3 have been prepared in ultrahigh vacuum by reactive evaporation of indium. X-ray diffraction, optical, and electrical measurements were used to characterize properties of films deposited on transparent insulating mica substrates under variation of the oxygen pressure. Photoelectron spectroscopy was used to investigate in situ the interface formation between In2O3 and the layered semiconductor InSe. For thick In2O3 films a work function of φ=4.3 eV and a surface Fermi level position of EF−EV=3.0 eV is determined, giving an ionization potential IP=7.3 eV and an electron affinity χ=3.7 eV. The interface exhibits a type I band alignment with ΔEV=2.05 eV, ΔEC=0.29 eV, and an interface dipole of δ=−0.55 eV.

Dielectric property and microstructure of a porous polymer material with ultralow dielectric constant

Abstract: This letter reports the synthesis and dielectric properties of a porous poly(arylethers) material with an ultralow dielectric constant for interlayer dielectric applications in microelectronics. The porous polymer films were fabricated by a method of organic phase separation and evaporation. A dielectric constant of 1.8 was achieved for a porous film with an estimated porosity of 40%. The characterization of microstucture for the porous film showed numerous nanopores with an average size of 3 nm distributed uniformly throughout the film.

Organic light-emitting element, device and method for manufacturing the same

Abstract: PROBLEM TO BE SOLVED: To provide a device and method of manufacturing an organic light- emitting element, capable of forming an evaporation layer on a substrate without displacement of the position of forming a film at a high speed, keeping the thickness of the film even and keeping the area of forming the film even, to be miniaturized and manufactured at a low cost. SOLUTION: A screen board 12 is mounted in a chamber 11 to divide the upper space and the lower space, and an oblong evaporation window 13 is formed in the screen board 12. An evaporation source 16 is disposed opposite to the evaporation window 13 under the screen board 12. A moving mechanism 17, for moving a substrate 1 relative to the evaporation window 13, is mounted on the screen board 12. A metal mask 20, as necessary, is mounted under the substrate 1 adjacent to the substrate 1. COPYRIGHT: (C)2001,JPO

Fabrication of Monolithic Ti3SiC2 Ceramic Through Reactive Sintering of Ti/Si/2TiC

Abstract: Fabrication of monolithic Ti3SiC2 has been investigated through the route of reactive sintering of Ti/Si/2TiC mixtures. Significant phase differences existed between the surface and the interior of as-synthesized products due to the evaporation of Si during the reaction process. The use of a 3Ti/SiC/C mixture as a powder bed could control the evaporation of Si and develop monolithic Ti3SiC2. A reaction model for the formation of Ti3SiC2 in the Ti/Si/2TiC system is discussed.

Direct growth of nanostructures by deposition through an Si3N4 shadow mask

Abstract: We propose a method for the simultaneous fabrication of a multitude of identical nanodots . Without any further lithographic procedures, structures in the regime of 100 nm and below can be directly prepared by vapour deposition while partly shadowing the substrate with a free standing stencil mask, – here an Si 3N4 membrane with an array of small holes. With such a mask very uniform dots of chromium have been grown on germanium substrates. They have the shape of truncated cones with a bottom diameter of about 550 nm. A reduction in size was achieved by applying a mask with reduced hole diameters ranging up to 300 nm. Due to a shift of the mask during evaporation, we obtained lines suggesting that even custom designed structures will be possible, if the lateral movement of the mask is precisely controlled.

Manufacture of organic el element and device therefor

Abstract: PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic EL element enabling minute patterns to be formed accurately and easily in the event of mask evaporation, and to provide a device therefor. SOLUTION: A transparent electrode 12 with a prescribed shape is formed of a transparent electrode material, such as ITO, on a surface of a transparent substrate 10 made of glass, resin, or the like, a luminescence layer made of organic EL materials is layered on the transparent electrode 12 by a vacuum thin-film forming technique, and a back plate made of Al-Li, etc., having a prescribed shape and confronting the transparent electrode 12 is formed on a surface of the luminescence layer. In forming the luminescence layer, a mask 20 with a stripe-shaped opening 22 (22a, 22b) is provided, and as to the opening 22 in the mask 20, the opening part 22a on the substrate 10 side is formed larger in width than the opening part 22b on the side of evaporation sources for the organic EL materials. The mask 20 and the substrate 10 are inclined with the mask 20 aligned with the substrate 10, the evaporating direction of the organic EL materials is successively changed for evaporation, and a plurality of organic EL materials are evaporated onto different positions on a surface of the substrate 10 by using the single opening 22 in the mask 20.

A new method for fabricating water repellent silica films having high heat-resistance using the sol-gel method

Abstract: There has been a great demand in the field of kitchen appliances to develop transparent water repellent films which have high heat-resistance around 300°C. However, those films have not been obtained by conventional sol–gel methods. In this paper, we propose a new method for fabricating transparent water repellent films with high heat-resistance using the sol–gel method, in which silicon or germanium substrates were coated with a solution including tetraethoxysilane (Si(OC2H5)4) and (2-perfluorooctyl)ethyltrimethoxysilane (CF3(CF2)7C2H4Si(OCH3)3), followed by `ammonia-treatment' and annealed at 300°C. The contact angles of water on the ammonia-treated film maintained its initial value, 110° after the heat treatment at 300°C for 250 h while those on the untreated film decreased to 70°, indicating that the ammonia-treatment improves heat-resistance on the film. The mechanism of ammonia-treatment was inferred from FT-IR results; the ammonia-treatment should accelerate hydrolysis and polymerization of FAS and TEOS molecules, resulting in high density of siloxane bonds between FAS and silica glass. These bonds suppress the evaporation of FAS molecules from the film during the heat treatment at 300°C, thus the film has high heat-resistance.

Formation of Thin Transparent Conductive Composite Films from Aqueous Colloidal Dispersions

Abstract: This investigation examines the percolation and electrical resistivity behavior of films containing electrically conductive antimony-doped tin oxide particles in different polymer matrices. The polymers include gelatin, a soft polymer latex (glass transition temperature Tg room temperature). The films are formed through the evaporation of water from aqueous dispersions of conductive particles and film-forming polymers. The critical volume fraction of conductive particles for conductive network formation was found to be significantly lower when the film former was a polymer latex. This was attributed to differences in the interactions of particles in the colloidal state prior to the point where particles start to touch. In the critical transition region or slightly above the critical transition region, the hard latex provides an order of magnitude improved surface resistivity compared to that of the soft latex. This result was discussed in terms of the po...

Silicon dioxide deposition by plasma activated evaporation process

Abstract: A method for coating a plastic substrate with an abrasion resistant metal oxide layer which includes placing the plastic substrate in a vacuum chamber, forming a vacuum in the chamber, conducting electron beam evaporation of an oxide-forming metal or a metal oxide in the vacuum chamber, passing the evaporated metal or metal oxide into an argon plasma into which oxygen and nitrous oxide has been passed, and, exposing the plastic substrate to the plasma, whereby the abrasion resistant layer is deposited on an exposed surface of the substrate.