Surface sensitive mode XAFS measurement of local structure of ordered Ge nanoclusters (quantum dots) on Si(001)

Pseudomorphous Ge films have been deposited on Si(0 0 1) substrate using mo lecular beam epitaxy at 300 degreesC up to the critical thickness of four m onolayers. As a result of the following deposition pyramid-like Ge islands have been grown in Stranski-Krastanov mode. The islands revealing quantum d ots (QD) properties are self-organized during the growth in uniform Ge nano structures with lateral sizes similar to 15 nm and height similar to 1.5 nm . Ge K XAFS measurements have been performed using total electron yield detec tion mode, It was established that pseudomorphous 4-monolayer Ge films cont ain about 50% Si atoms. It has been found that the Ge QD are characterized by interatomic Ge-Ge distances of 2.41 Angstrom which is 0.04 Angstrom less than in bulk Ge. (C) 2001 Elsevier Science B.V. All rights reserved.