Fabrication of ramp-type junctions using a two angle ion beam etching process

The development of tunnel junctions consisting of high-T-c superconductors (HTSs) and other perovskite transition metal oxides offers the possibility of creating a variety of new functional devices. The fabrication of such de vices represents a challenge with respect to both thin-film technology and the clarification of the underlying physics of charge transport across the involved barriers and interfaces. In particular, the use of manganite-HTS j unctions allows the study of spin-polarized charge injection into HTS and t he interaction between superconducting and ferromagnetic materials. Here, w e present recent advances in the fabrication of ramp-type junctions using i n situ surface cleaning by low-energy oxygen ions and two angle ion beam et ching. The latter process prevents the formation of redeposit and allows th e fabrication of hat surfaces in the ramp region. In our fabrication proces s the interfaces and surfaces between the different process steps have been characterized by atomic force microscopy and transmission electron microsc opy. The fabricated junctions have been characterized by standard electrica l measurements.