Self-Assembled Superlattice by Spinodal Decomposition during Growth

We examine the dynamics of alloy growth by vapor deposition and bulk diffusion, predicting a new type of self-organized growth. When material is deposited at a composition unstable against spinodal decomposition, we find three distinct regimes depending on growth rate. Intermediate growth rates lead to spontaneous formation of a superlattice with layers parallel to the surface. Slow growth leads to more complex three-dimensional decomposition. For fast growth, the alloy composition remains uniform near the surface, with a composition wave propagating up from the interface.