Tailoring the surface morphology of amorphous thin films by appropriately chosen deposition conditions

Amorphous thin film growth on a substrate by cocondensation is dominated by growth instabilities arising from self shadowing and surface diffusion, and these lead to pronounced three dimensional growth. It is possible to influence structure formation profoundly through systematic variation of the deposition characteristics of the particles, i.e., the deposition energy, the deposition angle, and the angle distribution. Experimentally, this can be achieved by varying the deposition technique from vapor deposition to sputtering, and changing the deposition angle with or without simultaneous rotation of the substrate. While roughening can be enhanced by oblique particle incidence, sputtered amorphous films have smooth surfaces. This behavior can be understood in terms of shadowing and energy transfer effects as illustrated by Monte Carlo and continuum growth models.