Long-lived excitons in Ge/Si nanosystems with germanium quantum dots

Dipole-allowed optical transitions between quasistationary and stationary exciton states, which occur over the spherical surface of a single germanium quantum dot embedded in a silicon matrix, are theoretically investigated. These optical electronic transitions, occurring in the real space of the silicon matrix, allowed to solve the problem of a giant increasing the lifetimes of exciton states in germanium/silicon heterostructures with germanium quantum dots. Long-lived quasistationary and stationary exciton states will make it possible to realize high-temperature quantum Bose-gases states in the nanosystem under study.