Silicon nanophotonics is emerging as a new platform for the integration of photonic and electronic devices. Several examples of recent efforts on monolithic light sources based on silicon nanostructures will be presented and discussed. In particular it will be shown that silicon-on-insulator (SOI) is emerging as an interesting photonic material. The first electrically pumped silicon-on-insulator nano light source, tunable around 1300-1600nm range and operating at room temperature will be presented. H-related optically active defects are properly introduced into silicon enhancing the electrically driven emission in a photonic crystal nanocavity device. A narrow (Δλ = 0.5 nm) emission line with the highest spectral power density ever reported from any silicon emitter will indeed be presented. Alternatively Er ions are introduced into the nanocavity showing an enhanced emission at 1500 nm with potentials for a population …