Molecular beam epitaxy in the presence of phase separation

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Abstract
Experiments have shown that phase separation during the growth of solid films by molecular beam epitaxy (MBE) is a phenomenon seen in a variety of systems. We study a MBE process where two types of particles are deposited simultaneously, and where the interatomic potential energy leads to phase separation. From a microscopic point of view, we describe the system with a solid-on-solid model augmented by an Ising model to represent the phase separation. Monte Carlo simulations of this model show that for low deposition rates, a lamellar pattern emerges in the bulk, with a modulation parallel to the growth plane. We show how the temperature and the deposition rate can be used to tailor the wavelength of the modulation. The effects of the phase separation on the surface morphology create a modulation consisting of steps or grooves at the interface between surface domains, which can be seen in the height-height correlation function and in the surface width. The temperature dependence of the surface width at fixed deposition rate is also presented.