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Computational Modeling of Nanostructure and Thin Film Growth


GLAD MC simulations

We have developed 3-dimensional (3D) Monte Carlo simulation methods in order to investigate the dynamic growth behavior of physical or chemical vapor deposited thin films, glancing angle deposited (GLAD) nanostructures, and also plasma etching of thin films. These simulation allows the effects of shadowing, re-emission (non-sticking of incident atoms/molecules), surface diffusion, and noise, which are among the most important processes during thin film growth. Simulations can also include the effects of substrate rotation for GLAD growth.

Simulations of GLAD on NSL seedsFor example, we recently have worked on modeling the growth of GLAD nanostructures grown on nanosphere lithography (NSL) patterned substrates.  In this study, ordered arrays of Si nanorods and nanospirals have been produced by ion beam sputter glancing angle deposition of Si on rotating substrates, at Prof. Rauschenbach’s group at Leibniz Institute of Surface Modification (IOM) in Leipzig, Germany. The substrates were pre-patterned with honeycomb and hexagonal-closed-packed (hcp) arranged Au dots obtained by NSL. The effects of template type, substrate rotational speed, height of the artificial Au seeds, and deposition angle of the incident flux on the growth of the Si nanostructures is examined. Especially for the deposition of Si on honeycomb templates at different deposition angles it is shown that the structure of the growing film changes drastically. A continuous film with honeycomb-like arranged hillocks on top is deposited at normal incidence. With increased the structure shifts to almost dense films with a mesh of hexagonally arranged pores ( = 70°). Finally, separated rod-like structures with triangular cross section are obtained under glancing angle conditions ( = 85°). The structural evolution of the glancing angle deposited Si films is compared with GLAD 3D Monte Carlo simulations (for example see Fig. 2). The effects of surface diffusion on the growth of spiral Si nanostructures on non-templated substrates in experiment and simulation were also compared.