Self-organised growth on structured substrates

The mechanism of ordering of germanium islands grown on relaxed silicon-germanium thin films has been elucidated. The growth experiments are carried out by the MBE group at Århus, and the results are analysed by atomic force microscopy at MIC. An objective of this research is to develop techniques for fabrication of monodisperse nanostructures that can serve as quantum dot structures for electronic or optical applications. The Ge islands were observed to grow along dislocations in the relaxed SiGe layers, on regions where the lattice was relaxed and there was a smaller mismatch with Ge. Work has been started to control the lattice relaxation of the substrate by prefabrication of mesa structures using laser.