The substrate surface morphology and the YBa2Cu3O7-x film growth on polycrystalline silver

Thin YBa2Cu3O7-x (YBCO) films were grown on the polycrystalline-silver by pulsed laser deposition (PLD). Using transmission electron microscopy (TEM), we have studied the direct relations of the YBCO film growth features with the substrate surface morphology. The obtained results show that the flat substrate surface is the only requirement for the c-axis oriented YBCO film growth. On the flat substrate surface, the YBCO film usually grows with its a-b plane simply parallel to the substrate surface plane. Any small angle change of the substrate sur face plane will cause the same angle change of the c-axis orientation of the grown YBCO film. On the defective surface with valleys, however, the YBCO film can not directly grow, instead, there is an intermediate layer previously grown on the substrate surface. Concerning the surface steps and hills, the TEM observation indicates that they almost have no influence on the YBCO film growth.