The fabrication of SiOx/SiO2 superlattices combined with thermal annealing enables the size and density control of Si quantum dots . The layered-arranged Si quantum dots represent a model system to systematically study the photonic and electronic properties of indirect gap quantum dots prepared in a CMOS compatible way. Hence, the model system is used to understand the interplay of absorption and recombination, the carrier kinetics and the electronic transport prop-erties for matrix embedded Si quantum dots. Starting with the temperature dependence of the size depending band gap  the interplay of radiative and non-radiative recombination will be discussed for high quantum yield [3-5]. Doping of quantum dots and the respective experimental techniques for its quantification is at the very limit of the nowadays experimental possibilities. Systematic doping experiments with P and B will be presented which will be analyzed for doping efficiency, in-cooperation into the Si NCs and self-purification effects [6, 7].