SURFACE-MORPHOLOGY AND IN-PLANE-EPITAXY OF SMBA2CU3O7-DELTA FILMS ON SRTIO3(001) SUBSTRATES STUDIED BY STM AND GRAZING-INCIDENCE X-RAY-DIFFRACTION

The surface morphology and in-plane epitaxy of thin films of SmBa(2)Cu 3O(7-delta) (Sm-BCO) grown on SrTiO3 (001) substrates with various thi cknesses have been investigated by scanning tunneling microscopy (STM) and grazing incidence x-ray diffraction (GIXRD). As revealed by GIXRD , SmBCO films as thick as 500 Angstrom grow pseudomorphically on SrTiO 3 (001) surfaces, in comparison with a maximum of 130 Angstrom for YBC O. This is probably due to a better lattice match of SmBCO (epsilon(al pha) = 1.2%, epsilon(b)=-0.5%) compared to YBCO (epsilon(alpha)=2.0%, epsilon(b)=0.5%) with the SrTiO3 substrate. Three different types of s urface morphology were observed by STM with increasing film thickness h: a) 2D growth for h<h(c1), b) columnar structures for h(c1) <h<h(c2) , c) spiral growth for h>h(c2). With GIXRD, a density modulation is ob served in the films with a thickness below h(c2). For thicker films ab ove h(c2), introduction of screw dislocations leads to spiral growth.