CORRELATION BETWEEN RAMP MORPHOLOGY AND PROPERTIES OF RAMP-TYPE JUNCTIONS

The correlation between the morphology of ramps in YBa2Cu3O7-delta thi n films prepared by ion-beam etching and the properties of ramp-type j unctions was investigated in detail. Ramp-type junctions were fabricat ed using PrBa2Cu2.9Ga0.1O7-delta as the barrier material, We examined the influence of different fabrication parameters on the ramp properti es by Atomic Force Microscopy (AFM). Properties of junctions, which we re fabricated by employing a postbaking of the etching mask, were comp ared with those of junctions prepared without ally special treatment. Junctions containing the improved ramps showed I-V characteristics and a temperature dependence of the normal resistance R-N typical for res onant tunneling, The other junctions, having also an order of magnitud e lower values of R-N, exhibited a metallic temperature dependence of R-N, which can be possibly explained by contributions from metallic ch annels in the PrBa2Cu2.9Ga0.1O7-delta-barrier.