The research field of silicon photonics aims at combining photonic and electronic components into an all-integrated, CMOS compatible platform for data processing systems. A main challenge is the development of efficient Si-based light sources in the telecom wavelength range which allows to replace metal wiring between and within microchips by optical interconnects. Furthermore, efficient single photon sources are a prerequisite for future integrated quantum optic devices. To overcome the poor optical properties of the indirect semiconductor materials Si and Ge, a promising approach is the growth of SiGe quantum dots (QDs) and the control of their emission properties by embedding them into Si-photonic structures. In the presented work fundamental optoelectronic properties of SiGe QD are investigated by photoluminescence (PL) spectroscopy on bare SiGe QD as well as on SiGe QDs embedded into photonic structures. ^Time-resolved PL measurements have been performed to gain insight into the PL dynamics and emission broadening mechanisms of randomly nucleated and site-controlled SiGe QDs. In order to quantify lifetimes of different recombination processes, a PL decay model was adapted and utilized as fitting routine for the recorded PL decay traces. Furthermore, different recombination channels in SiGe QDs with a Ge lean core were identified by controlled laser excitation of e-h pairs above and below the wetting layer.
Variations of the spontaneous emission of ordered SiGe QDs in dependence of the QDs position within the unit cell of a two dimensional photonic crystal (PhC) slab were investigated by a systematic positioning of QDs based on the Moiré effect. The dimensions of the hexagonal air hole pattern of the PhC slab and the SiGe QD array were chosen slightly different resulting in a Moiré pattern. ^As a consequence, within one Moiré period all relative positions of the QDs with respect to the PhCs unit cell were realized which allows for all optical super-resolution PL maps monitoring variations of PL yields as a function of the QD position within the unit cell of PhC. By additional, complementary time-resolved measurements and simulations the observed PL yield variations were attributed to the differences in the local density of states. Similarly, a single SiGe QD embedded into a PhC L3 cavity was used as a probe to map the local density of states. Overall, good agreement of the PL yield with the calculated electric field energy distribution has been demonstrated. Possible reasons for the deviations of the experimental findings with the expected values as determined by simulations were addressed by analyzing additional time-resolved measurements. The potential of state of the art SiGe QDs embedded into high-Q PhC cavities as single photon source are discussed. ^Finally a novel type of Ge quantum dots (named GIB dots or Ge-DEQDs) with extraordinary optical properties based on defect engineering is introduced. By embedding these QDs into microdisk resonators, optically pumped laser emission could be demonstrated.