(Hg,Re) Ba2CaCu2Oy thin films with improved surface morphology

We have succeeded in fabricating smooth and flat epitaxial (Hg,Re)Ba2CaCu2O y, thin films containing no appreciable pinholes and outgrowths. The films, with a thickness of approximately 75 nm, were prepared on (100) SrTiO3 sub strates (STO) by employing a two-step process, i.e., (1) preparation of thi n (approximately 100 nm) Re0.1Ba2CaCu2Oz precursor films using a pulsed las er deposition technique, and (2) heat treatments in Hg-vapor atmosphere. Ho mogeneous films with smooth surface have been obtained by simply using thin precursor films rather than thicker ones as previously employed (more than 200 nm). The average roughness R-a is 3-4 nm and the maximum peak-to-botto m surface roughness was about 10 nm. As-fabricated films exhibited the high est transport J(c) value of 1.0 x 10(7) A/cm(2) at 77 K in a self-field, al so indicating a substantial improvement. (C) 2000 Elsevier Science B.V. All rights reserved.