Shape preservation of Ge/Si(001) islands during Si capping

Coherently strained Ge/Si(001) islands were overgrown with Si at temperatures ranging from 300 to 550 degreesC. The induced shape changes were investigated at different stages of the capping process by scanning tunneling microscopy and high-resolution transmission electron microscopy. Islands were found to strongly flatten and intermix at temperatures above similar to450 degreesC. By contrast, a good shape preservation as well as the recovery of a flat Si surface above the buried islands can be achieved by low temperature capping at 300 degreesC followed by Si growth at 550 degreesC. (C) 2002 American Institute of Physics.