Phase separation in heteroepitaxial thin-film growth

We discuss the interplay between chemical ordering and surface roughening during molecular beam epitaxy. We propose microscopic and mesoscopic descriptions of homogeneous growth where two types of atoms are deposited, and where the interatomic potential energy leads to phase separation. For deposition rates below a certain threshold value, lamellar patterns emerge in the thin film, with the concentration modulation oriented in the growth plane direction. We find that patterning of the bulk is possible by varying the temperature and the deposition rate, in agreement with experimental results.