Reversible shape evolution of Ge islands on Si(001).
The evolution of strained Ge/Si(001) islands during exposure to a Si flux was investigated by scanning tunneling microscopy. Dome islands display appreciable shape changes at Si coverages as low as 0.5 monolayer. With increasing coverage, they transform into [105]-faceted pyramids, and eventually into stepped mounds with steps parallel to the <110> directions. These morphological changes are induced by alloying and represent a complete reversal of those previously observed during Ge island growth. The results are interpreted with a simple model in which the equilibrium shape of an island mainly depends on its volume and composition.
Rastelli
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INFM-Università di Pavia, Via Bassi 6, I-27100 Pavia, Italy. rastelli@solid.phys.ethz.ch
Kummer
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von Känel
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