EFFECT OF CHEMICAL AND ION-BEAM ETCHING ON THE ATOMIC-STRUCTURE OF INTERFACES IN YBA2CU3O7 PRBA2CU3O7 JOSEPHSON-JUNCTIONS/

The atomic structure of the interfaces of Josephson junctions formed b y epitaxial YBa2Cu3O7/PrBa2Cu3O7/YBa2Cu3O7- triple-layer films was inv estigated by high-resolution transmission electron microscopy. The sam ples were fabricated by sputter deposition on surfaces which were etch ed ex situ either chemically, using a nonaqueous Br-ethanol solution, or by an Ar ion beam. In the interfaces produced after ion etching a t hin intermediate layer with a thickness of a few nanometers was observ ed. The main part of this layer consists of cubic PrBa2Cu3O7 or YBa2Cu 3O7 which is cation disordered. The interfaces formed during depositio n on Br-ethanol-etched surfaces did not contain such an intermediate l ayer but exhibited high structural perfection similar to that of inter faces produced in situ. These observations permit a qualitative explan ation of the difference in the electrical properties of junctions prod uced by these two techniques. (C) 1995 American Institute of Physics