Local structure of self-organized uniform Ge quantum dots on Si(001)

Pseudomorphous Ge films with pyramid-like Ge islands have been deposited on Si(001) substrate using molecular beam epitaxy at 300 degreesC. The island s revealing quantum dots (QD) properties are self-organized during the grow th in uniform Ge nanostructures with lateral sizes similar to 15 nm and hei ght similar to 1.5 nm. Ge K XAFS measurements have been performed using tot al electron yield detection mode. It was established that the presence of a n appreciable exchange of atoms between the Si and Ge phases decreases the elastic strains in the system during the deposition of the blocking Si Laye r at 500 degreesC. It has been found that the Ge QD's are characterized by interatomic Ge-Ge distances of 2.41 Angstrom, which is 0.04 Angstrom less t han that in bulk Ge. (C) 2001 Elsevier Science B.V. All rights reserved.