Yttrium oxide deposition

This also illustrates the use of different wavelengths of light to obtain much more infomration on the nature of the film. Here A and T are plotted versus the wavelength of light ( ) and the line drawn tln-ough these data represents a fit calculated for the various fihns of yttrium oxide deposited on silica as shown at tire bottom of the figure [40],... 

Yttria thin films can also be deposited on Si substrates from Y(hfac)3 and Y(thd)3 by oxygen plasma-assisted CVD. It is found that with Y(hfac)3 the appropriate thin films were contaminated with fluorine, leading to unexceptional electrical properties. As discussed in Section V.A.4, next to yttrium oxide, SiOi and yttrium silicate are formed on the substrate surface. Pre-nitridation of the silicon surface impedes the reaction with the substrate. 

Test samples were fabricated by Si and Ge monohydrides pyrolysis in the gas mixture at the total pressure of 35-40 Pa with monogerman to monosilane volume ratio of 0.001-0.002. Temperature of the process was not higher than 680°C. P-doped silicon wafers (100) were used as substrates. Before the pyrolysis process we have oxidized the surface of some silicon wafers in dry oxygen in order to form thin silicon dioxide layer. In addition dysprosium and yttrium oxides were also formed on the wafer surface for other samples by the process of their deposition and following oxidation. 

Also, dielectric materials, especially, during the exposure to the atmosphere, absorb water and OH leads to detrimental interface reactions and water absorption and interface reactivity of yttrium oxide gate dielectrics on silicon was investigated. From the infrared absorption analysis, water vapor was significantly absorbed in the atmosphere. Similar oxidation are expected other high-K materials while the rate of OH absorption is expected to depend on the deposition process and their thermal history [29]. 

These results confirm that heat treatment promotes dehydration and crystallisation of yttrium oxide but also that complex diffusion phenomena occur. Adhesion of the deposit to the substrate is thus expected to increase. 

Jones L, Kumar D, Singh RK, Holloway PH. Luminescence of pulsed laser deposited Eu doped yttrium oxide films. Appl. Phys. Lett. 1997 71 404-406. DOI ... 

Electrical and Electronic Applications. Silver neodecanoate [62804-19-7] has been used in the preparation of a capacitor-end termination composition (110), lead and stannous neodecanoate have been used in circuit-board fabrication (111), and stannous neodecanoate has been used to form patterned semiconductive tin oxide films (112). The silver salt has also been used in the preparation of ceramic superconductors (113). Neodecanoate salts of barium, copper, yttrium, and europium have been used to prepare superconducting films and patterned thin-fHm superconductors. To prepare these materials, the metal salts are deposited on a substrate, then decomposed by heat to give the thin film (114—116) or by a focused beam (electron, ion, or laser) to give the patterned thin film (117,118). The resulting films exhibit superconductivity above Hquid nitrogen temperatures. 

The alkoxides and aryloxides, particularly of yttrium have excited recent interest. This is because of their potential use in the production of electronic and ceramic materials,in particular high temperature superconductors, by the deposition of pure oxides (metallo-organic chemical vapour deposition, MOCVD). They are moisture sensitive but mostly polymeric and involatile and so attempts have been made to inhibit polymerization and produce the required volatility by using bulky alkoxide ligands. M(OR)3, R = 2,6-di-terr-butyl-4-methylphenoxide, are indeed 3-coordinate (pyramidal) monomers but still not sufficiently volatile. More success has been achieved with fluorinated alkoxides, prepared by reacting the parent alcohols with the metal tris-(bis-trimethylsilylamides) ... 

The acetylacetonates are stable in air and readily soluble in organic solvents. From this standpoint, they have the advantage over the alkyls and other alkoxides, which, with the exception of the iron alkoxides, are not as easily soluble. They can be readily synthesized in the laboratory. Many are used extensively as catalysts and are readily available. They are also used in CVD in the deposition of metals such as iridium, scandium and rhenium and of compounds, such as the yttrium-barium-copper oxide complexes, used as superconductors. 1 1 PI Commercially available acetyl-acetonates are shown in Table 4.2. 

The deposition of thin films of the high-temperature superconductor yttrium-barium-copper oxide, YBa2Cu307, is obtained from the mixed halides, typically YCI3, Bal2, and CUCI2, with O2 and H2O as oxygen sources. Deposition temperatures are 870-910°C.f ]... 

Yttrium is also used in other areas of metallurgy notably as a component of certain nickel-base and cobalt-base superalloys of the NiCrAlY and CoCrAlY type.(3) These alloys possess excellent corrosion and oxidation resistance, properties that have attracted the attention of the aero-engine industry where they are used as protective coatings on turbine blades. The alloys, when applied by vapour deposition, form an oxide coating that exhibits remarkable adhesion, a property attributed largely to the yttrium component acting to prevent the formation of voids at the oxide/substrate interface.(4)... 

Zirconium oxide has also been used as a substrate by itself. Researchers at Cornell University evaporated some of the yttrium superconductor with beams of high-energy electrons, deposited the vapors onto bits of the zirconia, and then etched a circuit pattern a fraction of an inch long. Not only did the superconductor film carry current of around 1,000,000 amps per square centimeter, but it conducted electrical impulses as brief as ten to fifteen-trilli-onths of a second without distortion—impossible with conventional materials—and at very high levels of current. Those incredibly short pulses raise the distinct possibility that an enormous amount of electronic data, not only in a computer but in a telephone line as well, can be transmitted via the new superconductors at ultrafast speeds. 

Growth by vapor deposition and oxidation (VDO) of Ce onto a substrate has been used successfully. The simplicity of this approach and its ability to be integrated into UHV systems designed for multiple surface diagnostic methods makes this a common technique for surface studies of chemisorption and surface reaction studies on model catalytic surfaces. Many of the ceria films used in work described below were produced in this way. Ce deposition and oxygen exposure (oxidation) may be performed simultaneously or sequentially. - Single crystal metals (Pt, Cu, Pd, Ni, and Ru ) and oxides, including yttrium-stabilized zirconia (YSZ), and sapphire, have been used as substrates for this approach. Such films have been... 

In general, both cordierite and metallic monoliths are unsuitable as catalytic supports. To process a monolith into an active monolithic catalyst, a layer of porous catalytic support must be deposited on the walls between channels. y-Alumina appeared to be the most effective support for automotive catalysts. The alumina layer is deposited by sol-gel technique (so called washcoating). Adherence of 7-alumina to cordierite is relatively strong. However, to form the stable 7-alumina layer on a metallic surface, we need to use an appropriate alloy that is appropriately processed before the layer is deposited. Stainless steel containing chromium, aluminum, and yttrium subjected to thermal treatment under oxidizing conditions meets requirements of automotive converters. Aluminum in the steel is oxidized to form 7-alumina needles (whiskers) protruding above the metal... 

Galvanostatic electrosynthesis of an Y-Ba-Cu oxide precursor was accomplished [231]. The incorporation of yttrium into the oxide from the solution did not take place, so a YCU4 alloy was used as the substrate. In a saturated Ba(OH)2 solution, and also in 7.2 m KOH with Ba + additives, a loose black layer of amorphous deposit was formed on the anode surface. The layer spontaneously detached and fell to the bottom of the cell. Being annealed in air, it was transformed into a mixture of the YBCO, CuO, and Ba2Cu03 phases. 

Mazdiyasni et al. (584) were successful in depositing Zr02/Hf02 by a similar route as well as the oxides of yttrium, dysprosium, and ytterbium from their isopropoxides at about 250°C under an atmosphere of nitrogen. More recently, deposition of A1203 on InP was reported (585) by the thermolysis of A1(0-/-Pr)3 and also of Ti02 and Ta205, respectively, from their ethoxides (586). 

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