Electronic structure of Ge/Si quantum dots

We have investigated theoretically the strain distribution in pyramid-shaped Ge/Si quantum dots (QDs) and their environment, using the atomistic approach and the Green function technique. Taking, into account the results of strain calculations, we have studied the hole discrete spectrum by the tight-binding method. Energy levels, their dependence on dot size and wavefunction density distributions have been obtained. We have proposed a method for calculation of the Lande factor for localized states in QDs and calculated the value of the 10 actor for the ground state in the Ge/Si dot. We have developed a theoretical model of spatially indirect excitons and excitonic complexes, localized on the QD. The binding energy and optical transition energy have been calculated for excitonic complexes with different numbers of electrons and holes.