Breakup and grain growth in thin-film array

The problem of the morphological evolution in a polycrystalline thin film during annealing is examined by considering a periodic array in a 2D film. The combined motion of the surface moving by diffusion, and the grain boundary, which moves due to its curvature, is presented as a self-consistent problem. The analysis of this problem leads to two distinct kinetics, namely, (a) film breakup: when the grain size is larger than the film thickness, the surface relaxation is primarily a result of its interaction with a single grain boundary, the groove grows until the film breaks up; and (b) grain growth: when the two adjacent grooves interact before breakup happens, grain growth occurs by means of grain annihilation. Asymptotic analysis of the final stage of grain annihilation reveals the dependence of the groove velocity on the two interface energetic. Numerical analysis of boundary/surface motion demonstrates the morphological evolution with time, and establishes the conditions of transition between the two different regions.