Self-assembly of Ge quantum dots on Silicon: An example of controlled nanomanufacturing

We have grown Ge quantum dots by Physical Vapor Deposition (PVD) on step bunched Si(111) surfaces, vicinal Si(001) surfaces and oxidized Si substrates. Control of one- and two-dimensional ordering of the islands was obtained combining top-down patterning techniques (Focused Ion Beam milling), naturally occurring instabilities and anisotropies typical of Si surfaces. Real-time study of growth kinetics and self-organization of the islands has been accomplished using Scanning Tunnelling Microscopy imaging in UHV. A software routine was used to analyze the in-plane ordering of the islands on selected images. We focused on the study of the first nucleation stages of the dots on high-miscut vicinal Si(001) surfaces, in an attempt to correlate the observed behavior with the properties of these surfaces. The relevance of this research to quantum-dots based technology is also discussed.