LIQUID PHASE EPITAXY OF HT_c SUPERCONDUCTORS. P. Görnert, T. Aichele, S. Bornmann, C. Dubs, Institut für Physikalische Hochtechnologie e.V., Helmholtzweg 4, PF 100 239, D-0?702 Jena, Germany

YBa₂Cu₃O_7-x films were grown on (110) NdGaO₃ substrates by liquid phase epitaxy (LPE) using the "step cooling technique". A transition from c-axis to a- axis orientation could be observed with increasing undercooling for different flux melt compositions. Polygonized macrosteps were revealed optically at c- axis films grown at small undercoolings. Atomic force microscopy (AFM) measurements show that macrosteps are composed of a multitude of smaller growth steps. Besides decorated step structures were found on terraced surfaces between the macrosteps. The high quality of epitaxy has been confirmed by X-ray diffraction measurements showing rocking curve widths (FWHM) of 0.2-0.3deg. for the (005) film reflection. Larger undercoolings of the flux melts result in mixed c/a-axis growth and finally in a-axis growth reported already earlier.