Role of ion beam etching in the fabrication of ramp-type junctions

The use of ramp-type junctions is not only limited to the fabrication of Jo sephson junctions for ultrafast high-temperature superconducting electronic s but is also well suited for the controlled coupling of crystallographical ly compatible oxide materials such as ferromagnetic manganites and supercon ducting cuprates, Transport processes of ramp-type junctions strongly depen d on the ramp interface generated in the fabrication process. With regard t o the high potential of ramp-type junctions in the study and application of oxide materials, a detailed investigation of the process of ramp formation by modern surface analytical methods is highly desired. The enormous chall enge in the fabrication of ramp-type junctions consists in the necessity of the engineering of the involved interfaces on a unit-cell length scale. We present a detailed study of the ramp formation by ion beam techniques. Spe cial focus is put on the prevention of recrystallization of ion milled mate rial which poses a major problem to the formation of atomically smooth ramp interfaces with desired stoichiometry. (C) 2001 Elsevier Science B.V. All rights reserved.