Stress induced surface melting during the growth of the Ge wetting layer on Si(0 0 1) and Si(1 1 1)

We compute the isotropic stress for a Ge film deposited on Si(0 0 1) and Si(1 1 1) at T=870 K. By direct comparison with experimental phase diagrams measured for bulk Ge we deduce that Ge melts—at least partially—when deposited on Si surfaces at this temperature, due to the high heteroepitaxial stress (in the range 1–10 GPa), which has also been reported in experimental studies. Surface melting (complete or incomplete) induced by heteroepitaxial stress is consistent with a recent theoretical model proposed in the literature, and may account, at least in part, for the large values of Ge/Si intermixing reported in other studies.