Correlation between ramp morphology and properties of ramp-type junctions
The correlation between the morphology of ramps in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films prepared by ion-beam etching and the properties of ramp-type junctions was investigated in detail. Ramp-type junctions were fabricated using PrBa/sub 2/Cu/sub 2.9/Ga/sub 0.1/O/sub 7-/spl delta// as the barrier material. We examined the influence of different fabrication parameters on the ramp properties by Atomic Force Microscopy (AFM). Properties of junctions, which were fabricated by employing a post-baking of the etching mask, were compared with those of junctions prepared without any special treatment. Junctions containing the improved ramps showed I-V characteristics and a temperature dependence of the normal resistance R/sub N/ typical for resonant tunneling. The other junctions, having also an order of magnitude lower values of R/sub N/, exhibited a metallic temperature dependence of R/sub N/, which can be possibly explained by contributions from metallic channels in the PrBa/sub 2/Cu/sub 2.9/Ga/sub 0.1/O/sub 7-/spl delta//-barrier.