Growth and Transport Properties of Tunneling Barriers in HTS devices

G.J. Gerritsma, M.A.J. Verhoeven, R. Moerman, D.H.A. Blank, H. Rogalla

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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.
Original languageEnglish
Title of host publicationEpitaxial oxide thin films II
Subtitle of host publicationsymposium held November 26-30, 1995, Boston, Massachusetts, U.S.A.
EditorsJames S. Speck
Place of PublicationBoston, MA, USA
PublisherMaterials Research Society
Number of pages10
ISBN (Print)1-55899-304-5
Publication statusPublished - 14 Jan 1996
EventSymposium on Epitaxial Oxide Thin Films II - Boston, United States
Duration: 26 Nov 199530 Nov 1995
Conference number: 2

Publication series

NameMaterials Research Society Symposium Proceedings
PublisherMaterials Research Society


ConferenceSymposium on Epitaxial Oxide Thin Films II
Country/TerritoryUnited States


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