Dynamics of rough interfaces in chemical vapor deposition: Experiments anda model for silica films

We study the surface dynamics of silica films grown by low pressure chemica l vapor deposition. Atomic force microscopy measurements show that the surf ace reaches a scale invariant stationary state compatible with the Kardar-P arisi-Zhang (KPZ) equation in three dimensions. At intermediate times the s urface undergoes an unstable transient due to shadowing effects. By varying growth conditions and using spectroscopic techniques, we determine the phy sical origin of KPZ scaling to be a low value of the surface sticking proba bility, related to the surface concentration of reactive groups. We propose a stochastic equation that describes the qualitative behavior of our exper imental system.