Coarsening dynamics of crystalline thin films

The formation of pyramidlike structures in thin-film growth on substrates w ith a quadratic symmetry, e.g., {001} surfaces, is shown to exhibit anisotr opic scaling as there exist two length scales with different time dependenc es. Numerical results indicate that for most realizations coarsening of mou nds is described by an exponent n similar or equal to 1/4. However, dependi ng on material parameters it is shown that n may lie between 0 (logarithmic coarsening) and 1/3. In contrast, growth on substrates with triangular sym metries ({111} surfaces) is dominated by a single length similar to t(1/3).