The dewetting properties of $\mathrm{Ge}/{\mathrm{SiO}}_2$ have been studied by low-energy electron microscopy and grazing incidence small-angle x-ray scattering in two temperature ranges characterized by the presence or the absence of {15 3 23} facets on the dewetting fronts. Thanks to a comparison with the $\mathrm{Si}/{\mathrm{SiO}}_2$ system, we show that the {15 3 23} facets: (i) play a role in the stabilization properties of Ge dewetting fronts, (ii) lead to a rotation of ${45}^{\circ }$ of the Ge fingers with respect to the Si fingers, and (iii) increase the Ge fingers’ stability delaying the formation of a three-dimensional Ge islands with respect to Si for the benefit of the formation of Ge nanowires. Studying the dewetting kinetics enables estimating the activation energy for Ge dewetting to $2.7\pm 0.2\mathrm{eV}$. The weak energetics differences between Si and Ge systems are sufficient to change the dewetting morphologies from a squared-void opening for $\mathrm{Si}/{\mathrm{SiO}}_2$ to multibranch dendrites for Ge with specific consequences on the relative dewetting velocities of the $\mathrm{Si}/{\mathrm{SiO}}_2$ and $\mathrm{Ge}/{\mathrm{SiO}}_2$ systems.

• Received 7 May 2013

DOI:https://doi.org/10.1103/PhysRevB.88.035306