Coarsening dynamics of crystalline thin films

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