Yttrium thin film

Curzon and Singh (1979) report anomalous resistivity behavior of yttrium thin films as a function of the thickness (fig. 5). The results are explained in terms of faint contamination (H2, O2) and of defect scattering. So, the results of Kosak et al. (1987), Loboda and Protsenko (1981a,b), Loboda et al. (1980, 1982) and Protsenko (1988), relative to Sc thin layers, must be examined with much wariness (see sect. 2.8). 

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 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 ]... 

Film Critical Current Densities Critical current densities of thin films have been reported by several hundreds of papers a few representative but by no means inclusive are noted here in addition to those mentioned above. Desirable attributes of thin films for technology are high transition temperature to zero resistance, high critical current, low substrate temperature during deposition, no high temperature post anneal, and atomically smooth surface without pinholes. A thermal coevaporation of yttrium, barium, and copper in an oxygen atmosphere have been deposited by Berberich (34) on substrates at 650°C with Tc s of 91 K on MgO and 89 K on SrTiOs without post anneal. Although critical currents of 106 A/cm2 were obtained at 4 K, values of 104 A/cm2 were found at 77 K. However,... 

The cathodoluminescence of thin films containing rare-earth oxides was studied by Hansen and Myers (140). Films of yttrium oxide doped with rare earths were prepared in vacuum by electron-bombardment evaporation of the oxide powder mixtures. Luminescent rise and decay curves were obtained for activation with europium, gadolinium, terbium, and dysprosium. 

Routes to monomeric , mononuclear , monolanthanide alkoxides, enolates, siloxides and aryloxides - an expanded title which will put the scope of the article in a more concrete form. The synthesis of mononuclear alkoxides, in particularly homoleptic derivatives [1], was decisively stimulated by the discovery of high temperature superconducting ceramics based on YBa2Cu307<, where yttrium represents the lanthanide elements [2]. The support of volatile and highly soluble molecular precursors is a prerequisite for synthesizing thin films of these materials by means of MOCVD [3] and sol gel processes [4], respectively. More recently, lanthanide alkoxide reagents became established in... 

Magnetic properties are important in the function of electronic devices. An example is the use of yttrium iron garnet (YIG) in microwave devices. On applying an external magnetic field to a YIG disk, the input, say energy of one particular frequency selectively passes to the output. Thin films based of YIG within which magnetic waves can pass have proven to be useful. The use of lanthanides in magnetic devices as transducers is listed in Table 12.18. 

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. 

IBM researchers managed that trick in 1987, reporting that they had attained a critical current of over 100,000 amps per square centimeter in a thin film of one of the yttrium mixtures cooled by liquid nitrogen. The experiment was accomplished by growing single crystal samples and large grains of the materials in which the crucial... 

The syntheses, physical properties, and molecular structures of alkoxides and aryloxides have been discussed in CCC (1987).161 The alkoxides of scandium and yttrium were reviewed in CCC (1987).1 There have been more recent developments in this area and the impetus for this chemistry has been the developments in materials research. Metal alkoxides and /3-diketonates can be used as precursors for oxide and nonoxide thin films.162 The stable M—O bond and the volatility of the metal alkoxides are important features of this area of chemistry. This has lead to more research in this area particularly in synthesis, NMR, and X-ray crystallography. 

Interest in barium yttrium alkoxides stems from metal organic vapor deposition experiments for the preparation of superconducting thin films. The compound [Y4Ba20(0Et)8(dmp)6] (where dmp = B C CHC Bu1) has been prepared by the reaction of Y50(0Pr1)13 with Ba(OEt)2 (PPOH) in the presence of dmpH.167 The structure contains seven-coordinate yttrium atoms with... 

Yttrium is currently used in the production of plastics as a catalyst for ethylene polymerization, while yttrium additives are used to improve the properties of many ultra-thin films composed of organometallic complexes. 

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