GROWTH OF (110)-ORIENTED EPITAXIAL RBA2CU3O7-DELTA THIN-FILMS AND CHARACTERIZATION WITH RAMAN-SPECTROSCOPY

High-quality superconducting (110) and (103)/(013)-oriented SmBa2Cu3O7 -delta thin films, with T-c approximate to 90 K, have been grown on Sr TiO3 (110) substrates using pulsed laser deposition. The (110) orienta tion was obtained using a PrBa2Cu3O7-delta buffer layer. The structure of the films has been investigated with atomic force microscopy (AFM) and Raman spectroscopy. AFM revealed a granular stripe-like surface m orphology. The orientation of the films was determined from Raman meas urements by comparing the intensity of the O(4) A(g) mode, the linesha pe of the Ba A(g) mode and the intensity of the O(2)-O(3) out of phase A(g) mode taken in different polarization geometries. Faint B-2g, B-3 g and oxygen defect modes of the SmBa2Cu3O7-delta system were also res olved in the low temperature Raman spectra of the (110)-oriented film. A method for assessing the phase of the complex Raman tensor componen ts of the A(1g)-like modes has been devised. It is illustrated for the case of the 114 cm(-1) Ba A(1g) phonon: at 514.5 nm laser energy a ph ase difference of (2 +/- 0.2) rad is found between the xx (yy) and zz Raman tensor components. (C) 1997 Elsevier Science B.V.