Modeling the decay of nanopatterns: A comparative study between a continuum description and a discrete Monte Carlo approach

MARCOS F. CASTEZ; EZEQUIEL V. ALBANO

The Journal of Physical Chemistry C

American Chemical Society

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 forthe proper rates of all processes involved allows us to implement a real time algorithm. Thus, the relationshipbetween real time and Monte Carlo time is discussed. By using this discrete approach, we recover the mostrelevant results expected from the linear theory of surface diffusion for initial surfaces within the small-slopeapproximation. 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 anonexponential 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. Wecompare results obtained by using the proposed discrete model with the expectations of the standard continuoustheory of surface diffusion, and we show that many qualitative aspects are common to both approaches, inspite of the important differences between both descriptions.