The aim of this activity is the synthesis and characterization of Si and Ge nanostructures, mainly quantum dots, immersed in dielectric Si-based thin film matrixes (e.g. Si oxides and nitrides). These low dimensional materials are produce by PVD (sputtering), CVD, ion implantation and colloidal solution techniques. Critical issues are the size and density control of the quantum dots, as well as the reliability and reproducibility of the material. as tunable and efficient systems for the conversion of solar energy. The field of activity is in strong overlap with that of the optoelectronics, since the same or similar structures are proposed as very efficient light detectors. The use of quantum dots should enable the optical bandgap engineering is devices fabricated with relatively low cost and Si-based materials, in the idea of the “all Si” multi-junctions solar cells proposed years ago by the group of prof. Martin Green (SWAU). The main issue in the field of Si and Ge quantum dots immersed in dielectric transparent films is the extraction of the e-h pairs form the insulating matrix. Most of the research, in fact, is focused on the overcome of this practical problem.