Growth and Transport Properties of Tunneling Barriers in HTS devices


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Gerritsma, G.J. and Verhoeven, M.A.J. and Moerman, R. and Blank, D.H.A. and Rogalla, H. (1996) Growth and Transport Properties of Tunneling Barriers in HTS devices. In: Symposium on Epitaxial Oxide Thin Films II, November 26-30, 1995, Boston, MA, USA (pp. pp. 287-296).

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Abstract:In this contribution we will discuss the charge transport of ramp-type HTS Josephson junctions with a Ga-doped PBCO barrier layer. It will be demonstrated that in these junctions charge transport takes place via tunneling processes. The Cooper pairs tunnel directly, at least for T ≤ Tc/2, whereas the quasiparticles tunnel indirectly via localized states. By substituting Cu-chain atoms with Ga-atoms the density of localized states appear to be reduced, resulting in an increase in IcRn-product. Another way to increase this product is a reduction in barrier thickness. Growth studies by AFM of PBCO barriers on ramps indicate that below about 10 nm barriers become increasingly less homogeneous, and below about 6 nm pin holes are very likely to occur. This sets a lower limit on the useful barrier thickness. Presently critical-current densities up to 104 A/cm2 at 40 K, and IlR,-products up to 10 mV at 4.2 K are easily obtained.
Item Type:Conference or Workshop Item
Copyright:© 1996 MRS
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Science and Technology (TNW)
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Link to this item:http://purl.utwente.nl/publications/25551
Official URL:http://dx.doi.org/10.1557/PROC-401-287
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Metis ID: 130353