Anomalous kinetic roughening by chemical reaction-limited aggregation

The evolution of rough fronts in the early growth stage of poly(chloro-p-xylylene) films on Si/SiO₂ substrates was measured using atomic force microscopy, and analyzed in detail according to the dynamic scaling theories of kinetic roughening. While the growth of the interface width and the correlation length were reduced as the system entered into the three-dimensional growth mode, both the global and the local roughness exponents remained at α = 1:39 and α_loc = 0:74. The scaling behavior, α = α_s ≠ α_loc for α_S > 1, was categorized as the super-roughening process, but the characteristic scaling parameters could not be classified into any known universality classes based on local growth models. The unconventional scaling characteristics and the interesting crossover behaviors in the kinetic roughening were attributed to the delicate changes in the intermolecular interactions associated with the chemical reaction-limited aggregation.