Reaction-diffusion approach to nanostructure formation and texture evolution in adsorbed monoatomic layers

It is shown that coverage evolution, during atomic deposition on a substrate, may be described, on mesoscopic scales, by dynamical models of the reaction-diffusion type. The models combine reaction terms representing adsorption-desorption processes and nonlinear diffusion terms of the Cahn-Hilliard type. The combination may lead, below a critical temperature, to the instability of uniform deposited layers. The instability induces to the formation of nanostructures that correspond to regular spatial variations of atomic coverage. Such models also may describe texture evolution during the deposition of polycrystalline films. In this case, grains with different orientations with respect to the substrate may coexist. Grains with lower surface energy usually dominate, except at high temperatures, where grains with faster lateral diffusion may override energetically favored ones. Furthermore, at sufficiently low temperatures, uniform grain distributions may become unstable versus regular spatial variations of grain orientations. The relevance of this approach to the deposition of Al or Cu on TiN or Ta substrates is discussed. © 2004 Wiley Periodicals, Inc.SCOPUS: cp.jFLWIN