Ordering and electronic properties of self-assembled Si/Ge quantum dots

We have combined Ge island nucleation during molecular beam epitaxy in the Stranski-Krastanow growth mode with step bunching in Si/SiGe multilayers, o n vicinal Si substrates in order to realize self-ordered arrays of nanostru ctures. Surface steps and the local strain fields surrounding strain-relaxe d SiGe nanostructures influence the island nucleation and result in spatial ly ordered stable arrays of Ge dots. The controlled formation of vertically correlated stacks of wires, dots or dots on wires by such self-ordering pr ocesses offer novel functionality for future applications like infrared det ectors and memories. The fundamental electronic and optical properties of s elf-assembled Ge dots embedded in Si are analyzed by photoluminescence, adm ittance and intra valence band photocurrent spectroscopy.