Growth of elongated nanostructures

Growth of elongated nanostructures from the gas phase on a masked substrate is modeled using the continuous time Monte Carlo method with the solid-on-solid approximation. We have found that the masked substrate imposes anisotropy on the growth of elongated nanostructures. Thus growth occurs either by nucleation of a single cluster in the short direction and wave propagation in the long direction or by formation of multiple nuclei followed by propagation of waves along the long direction. The growth rate of nanostructures depends significantly on their size. Narrow nanostructures grow about two orders of magnitude slower and there is a size-dependent critical supersaturation for growth to occur. This behavior is explained in terms of the thermal stability of nanostructures.