Surface sensitive mode XAFS measurement of local structure of ordered Ge nanoclusters (quantum dots) on Si(0 0 1)

Pseudomorphous Ge films have been deposited on Si(0 0 1) substrate using molecular beam epitaxy at 300°C up to the critical thickness of four monolayers. As a result of the following deposition pyramid-like Ge islands have been grown in Stranski–Krastanov mode. 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. AFS measurements have been performed using total electron yield detection mode. It was established that pseudomorphous 4-monolayer Ge films contain about 50% Si atoms. It has been found that the Ge QD are characterized by interatomic Ge–Ge distances of 2.41 Å which is 0.04 Å less than in bulk Ge.