The detailed morphological evolution during the transition between hut clusters and dome clusters is examined for ${\mathrm{Si}}_{0.8}{\mathrm{Ge}}_{0.2}/\mathrm{Si}\left(001\right)$ heteroepitaxy. Simultaneous real-time light scattering and stress measurements directly demonstrate the correlation between island impingement and the shape transformation. We show that elastic interactions between islands can significantly reduce the equilibrium transition volume and may also modify the activation barrier for the transition.

• Received 7 January 1998

DOI:https://doi.org/10.1103/PhysRevLett.80.4717