Modeling the Decay of Nanopatterns: A Comparative Study between a Continuum Description and a Discrete Monte Carlo Approach.

F CASTEZ,; EZEQUIEL V ALBANO

J Chem Phys C

American Chemical Society

Lugar: Washington; Año: 2007 vol. 111 p. 4606 - 4613

The surface-diffusion-driven decay of 2-dimensional periodic nanopatterns is studied by means of a kineticMonte Carlo model. Activation energy barriers are computed by using a harmonic approach. Accounting for the proper rates of all processes involved allows us to implement a real time algorithm. Thus, the relationship between real time and Monte Carlo time is discussed. By using this discrete approach, we recover the most relevant results expected from the linear theory of surface diffusion for initial surfaces within the small-slope approximation. We also focus on the decay kinetics of periodic nanopatterns (sinusoidal and rectangular) starting from nonequilibrium states far from the small-slope approximation. In this case, we found a nonexponential decay as well as the emergence of several interesting nanostructures (overhangs, nanoislands, nanovoids, etc.), which depend on the geometrical properties (e.g., the aspect ratio) of the initial pattern. We compare results obtained by using the proposed discrete model with the expectations of the standard continuous theory of surface diffusion, and we show that many qualitative aspects are common to both approaches, in spite of the important differences between both descriptions.