A molecular dynamics simulation of inhomogeneous silicon–germanium nucleation from supersaturated vapor mixtures

Abstract

The inhomogeneous nucleation of silicon–germanium (Si–Ge) systems from supersaturated vapor mixtures was investigated using molecular dynamics simulations. Isothermal simulation runs were performed using the Tersoff potential at various supersaturations and temperatures. We focused on the inhomogeneous dynamics, nucleation rate, and critical cluster size, as well as the effect of inhomogeneity on the quantitative results. The study showed that Si atoms nucleate much faster than Ge atoms. This may lead to the inhomogeneity and final production of Si-rich critical clusters. Such inhomogeneity may also stem from the different chemical properties of Si and Ge atoms. Under the tested conditions, the nucleation rates were within 1033–1036 J/m−3 s−1. They were influenced significantly by the supersaturation and slightly by the temperature. The critical size of 2.5–4.5 atoms was heavily dependent on both the supersaturation and temperature. Our results are generally consistent with those from other nucleating systems using the same method. The inhomogeneity of the Si–Ge system has no significant effect on the nucleation rate but may contribute to smaller critical cluster sizes at low temperatures.