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

Abstract

Pseudomorphous Ge films with pyramid-like Ge islands have been deposited on Si(001) substrate using molecular beam epitaxy at 300°C. The islands revealing quantum dots (QD) properties are self-organized during the growth in uniform Ge nanostructures with lateral sizes ∼15 nm and height ∼1.5 nm. GeK XAFS measurements have been performed using total electron yield detection mode. It was established that the presence of an appreciable exchange of atoms between the Si and Ge phases decreases the elastic strains in the system during the deposition of the blocking Si Layer at 500°C. It has been found that the Ge QD's are characterized by interatomic Ge–Ge distances of 2.41 Å, which is 0.04 Å less than that in bulk Ge.