EPITAXIAL QUALITY OF C-AXIS AND A-AXIS ORIENTED YBA2CU3O7 FILMS CHARACTERIZATION BY RAMAN-SPECTROSCOPY

We present a model that describes the epitaxial quality of YBa2Cu3O7 f ilms by three parameters - the c-axis oriented fraction of the film, i ts degree of in-plane orientation and the degree of in-plane orientati on of the remaining a-axis oriented fraction. These parameters can be specified by the relative phonon intensities in polarized Raman spectr a. We have determined the epitaxy parameters of a-axis and c-axis orie nted laser-deposited YBa2Cu3O7 films on MgO (100) substrates. The accu racy of these parameters has been tested by performing Raman measureme nts at various rotation angles. The ratio of the intensities of the B- 2g and B-3g modes observed on the a-axis oriented film indicates that a-axis growth is preferred to b-axis growth.