Influence of nanoscale substrate curvature on growth kinetics and morphology of surface nuclei

Results on numerical modeling of the influence of a substrate's nanoscale curvature on nucleation, growth kinetics, and morphological stability of nuclei during thin film vapor deposition are given. The problem is considered within the framework of the continuum surface diffusion equation taking into account the dependence of the adsorption energy, chemical potential, and the relevant surface mass fluxes on the surface curvature, together with the effect of surface self-shadowing from direct collisions from the gas phase and the contribution of readsorption fluxes. The nuclei growth kinetics are described by an Arrhenius type equation. Linear perturbation analysis of the growth model shows that positive nanoscale curvature (a concave surface) is able to considerably increase the (i) prenucleation concentration and thereby to increase the probability of nucleation and even to enable nucleation on substrates which do not have an affinity for nucleation under the given operating conditions, (ii) to increase considerably the growth rate of surface nuclei, and to lead to (iii) dramatic changes in morphology. (C) 1998 American Institute of Physics. [S0021-8979(98)04624-6].