FRACTAL FORMATION IN SPUTTERED FILMS OF BI2SR2CACU2O7-X ON SI SUBSTRATES

Fractal regions appearing in BSCCO films after annealing have been inv estigated by atomic force microscopy and transmission electron microsc ope. The fractal dimensions and fractal density (number of fractals pe r unit area) are temperature dependent. At lower annealing temperature (450 degrees C) both the morphologies and fractal dimensions closely resemble those arising in two dimensional diffusion-limited-aggregatio n (DLA) simulations. The observation results show that after annealing at 600 degrees C or higher temperature, the fractal regions changed, even disappeared, which means the growth mechanism is very different f rom that of traditional DLA. A random diffusion and successive nucleat ion model has been proposed to explain the results.