Josephson tunnel junctions

The most exciting property of these materials is that thin polycrystalline films can behave as two dimensional Josephson Tunnel Junction Arrays (110) displaying remarkably good electromagnetic coupling (111) both as emitters and receivers. Alternating current to direct current conversion has been observed in bulk samples (112), but the thin film geometry allows use of one film as a radiation emitter, and another film as the receiver (111). 

See also Josephson Tunnel-Junction and Thin Films. 

In 1962, B. Josephson recognized the implications of the complex order parameter for the dynamics of the superconductor, and in particular when one considers a system consisting of two bulk conductors connected by a weak link." This research led to tile development of a series of weak link devices commonly called Josephson junctions. See also Josephson Tunnel-Junction. These devices hold much promise for achieving ultra high-speed computers where switching time is of the order of 1CT11 second. 

The problem of lateral modification of HTSC surface layers, and the local electrosynthesis of HTSCs on the surface of patterned substrates including the precursors is very interesting. Such processes can occur, for example, during electrooxidation of metals when the process in its initial stages takes place only on isolated microscopic regions. Thus, Josephon junctions on the surface of Bi-Sn alloys [222] and on ceramic YBCO samples [295,444] were obtained by using electrochemical oxidation without any special local techniques. But it is hard to control such oxidation processes, and sufficient reproducibility cannot be ensured for most systems. Josephson tunnel junctions based on electrochemically synthesized BKBO crystals have been described [445]. 

Fig. 27. (a) Fraimhofar diffiaction pattern for the critical current vs magnetic flux threading the junction barrier that is characteristic of a single Josephson tunnel Junction, (b) Diffraction patterns expected for a single corner Junction with s-wave (isotropic or anisotropic) and dj,2 2 pairing symmetry. After Wollman et al. (1995, fig. 1). 

Most electronic applications are based on the turmel effect between two superconductors that are separated by a weak (isolating) link that is only a few atomic layers thick. Currently, Nb and A1 are used preferably to build Josephson tunnel junctions (JTJs), whereas ceramic superconductors are stiU less common. However, the situation may soon change following the discovery of coherently emitting tera-Hertz radiation of intrinsic BSCCO JTJs (Ozyuzer et al., 2007). Some aspects of electronic applications are considered in detail at this point. 

Very large scale integration (VLSI) technology and electronic devices Carbides and diborides as field and thermal emitters, TiN as a diffusion barrier in metallization to Si semiconductors, resistive thermoconductive humidity sensors with TaN film, and Josephson tunnel junctions with NbN film. 

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R Cristiano, E Esposito, L Frunzio, S Pagano, L Parlato, G Peluso, GP Pepe, U Scotti di Uccio, H Akoh, M Aoyagi, H Nakagawa, S Takada. Influence of a NhN thick overlayer on Nb/AlOx/Nb high quality Josephson tunnel junctions for X-ray detection. Appl Phys Lett 67 3340, 1995. 

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