Type-II Ge/Si quantum dots

The electronic structure of spatially indirect excitons, multiparticle excitonic complexes, and negative photoconductivity in arrays of Ge/Si type-II quantum dots (QDs) are considered. A comparison is made with the well-known results for type-II III-V and II-VI QD heterostructures. The following fundamental physical phenomena are observed in the structures under study: an increase in the exciton binding energy in QDs as compared with that for free excitons in homogeneous bulk materials, a blue shift in the excitonic transitions during the generation of multiparticle complexes (charged excitons, biexcitons), and the capture of equilibrium carriers to localized states induced by the electric ield of charged QDs.