Growth mechanism and surface morphologies of Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+y/ thin films

In order to obtain high quality multilayer Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+y/ (SmBCO) coated conductors, it is indispensable to understand the surface growth mechanism of the SmBCO system. Using AFM, the step-and-terrace features due to 3D island growth are observed that are polygonal-like from the surface images. Steps and terrace width are approximately 1.2 nm in height and 30 nm in width, respectively. Spiral steps accompanied by screw dislocations were observed on the surface films of Ca doped SmBCO films. The spiral shapes of Ca doped SmBCO films are polygonal-like with width of ~80 nm. Using Ca-doping, the surface morphology of the SmBCO films changes from 3D island growth mode to spiral growth, and contributes to the flat surface of the SmBCO-multilayers.