Phase-separated Al–Si thin films

Phase-separated Al–Si films composed of Al nanocylinders embedded in an amorphous-Si matrix have been prepared by a sputtering method. By controlling the deposition rate, substrate temperature, and film composition, the average diameter of the Al cylinders can be varied systematically from less than 5to13nm with a cylinder density ranging from 1015 to in excess of 1016cylindersm−2. A three-dimensional simulation of phase separation in binary thin films was performed using a modified Cahn-Hilliard [J. Chem. Phys. 28, 258 (1958)] equation to understand the growth mechanism. The simulation studies indicate that the surface diffusion length and film composition are important factors which determine film morphology. Experimental and simulation studies are compared and discussed.