Transition states between pyramids and domes during Ge/Si island growth

Real-time observations were made of the shape change from pyramids to domes during the growth of germanium-silicon islands on silicon (001). Small isl ands are pyramidal in shape, whereas Larger islands are dome-shaped. During growth, the transition from pyramids to domes occurs through a series of a symmetric transition states with increasing numbers of highly inclined face ts. Postgrowth annealing of pyramids results in a similar shape change proc ess. The transition shapes are temperature dependent and transform reversib ly to the final dome shape during cooling. These results are consistent wit h an anomalous coarsening model for island growth.