Superconducting electronics - thin films

In 1962 a postgraduate student, Brian Josephson, working in the University of Cambridge, and later to win a Nobel Prize, predicted that Cooper pairs should be able to tunnel through a thin (approximately 1 nm) insulating barrier from one superconductor to another with no electrical resistance [46]. This quantum tunnelling was confirmed by experiment and is known as the Josephson effect . The superconducting electronic devices exploit Josephson junctions. 

For forming devices the well established methods for patterning in microelectronics, photolithography/etching, are exploited. 

The switching between states, a characteristic of Josephson junctions, is applicable to binary-based logic circuits there is no voltage across the junction for currents below the critical current 7C, but one appears for currents greater 

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Tunneling is a ubiquitous phenomenon. It is observed in biological systems (1), and in electrochemical cells (2). Alpha particle disintegration (3), the Stark effect (4), superconductivity in thin films (5), field-electron emission (6), and field-ionization (7) are tunneling phenomena. Even the disappearance of a black hole (or the fate of a multi-dimensional universe) may depend on tunneling, but on a cosmological scale (S-9). 

Tertiary bismuthines appear to have a number of uses in synthetic organic chemistry (32), eg, they promote the formation of 1,1,2-trisubstituted cyclopropanes by the iateraction of electron-deficient olefins and dialkyl dibromomalonates (100). They have also been employed for the preparation of thin films (qv) of superconducting bismuth strontium calcium copper oxide (101), as cocatalysts for the polymerization of alkynes (102), as inhibitors of the flammabihty of epoxy resins (103), and for a number of other industrial purposes. 

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. 

Some years later a more thorough discussion of the motion of pairs of electrons in a metal was given by Cooper,7 as well as by Abrikosov8 and Gor kov,9 who emphasized that the effective charge in superconductivity is 2e, rather than e. The quantization of flux in units hc/2e in superconducting metals has been verified by direct experimental measurement of the magnetic moments induced in thin films.10 Cooper s discussion of the motion of electron pairs in interaction with phonons led to the development of the Bardeen-Cooper-Schrieffer (BCS) theory, which has introduced great clarification in the field of superconductivity.2... 

The importance of materials science to U.S. competitiveness can hardly be overstated. Key materials science areas underlie virtually every facet of modem life. Semiconductors underpin our electronics industry. Optical fibers are essential for communications. Superconducting materials will probably affect many areas ceramics, composites, and thin films are having a big impact now in transportation, construction, manufacturing, and even in sports—tennis rackets are an example. 

Thin films of an amorphous-composite In/InO, which contain a metal-dielectric interface, have been studied (12)(13) and found to superconduct when the electron carrier density reaches a value of approximately 1020cm-3. This system, having a Tc of 2.5 to 3.2 K, has been described as exhibiting "interface-dominated superconductivity". 

Hopes that superconduction was possible in polymers were raised briefly in 2001, when Schon et al. (2001) reported superconductivity at 2.35 K in a thin film of polythiophene with an excess of electrons induced by an adjacent gate electrode. These and a number of other remarkable results obtained with thin films of organic materials could not, however, be duplicated by other workers, and were declared suspect by an independent committee set up by Bell Laboratories to investigate inconsistencies in the papers reporting these findings (Brumfiel, 2002). 

Electronic Structure of Solids Fluorides Solid-state Chemistry Halides Solid-state Chemistry Macrocyclic Ligands Metallic Materials Deposition Metal-organic Precursors Oxides Solid-state Chemistry Periodic Table Trends in the Properties of the Elements Sol-Gel Synthesis of Solids Sohds Characterization by Powder Diffraction Structure Property Maps for Inorganic Solids Superconductivity Thin Film Synthesis of Solids. 

Here, magnified more than 500 times, is a high-temperature superconducting thin-film electronic device known as a SQUID. It can be used for extremely sensitive magnetic measurements and is only one one-hundredth the thickness of a human hair. (Photo courtesy the IBM Corporation Research Division.)... 

We report here the synthesis and electronic transport measurements of high-quality single crystals of KsCfio Measurements of the dc electrical resiatlvlty p(T) show an intrinsic metal-like temperature dependence below room tempemture, with an extremely sharp transition to the superconducting ground state at 19.8 K no evidence is found for strong fluctuation effects near T. These results are in sharp contrast to the behavior of polycrystalline and thin film samples. 

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