Integration of light sources on a Si chip is one of milestone to establish new paradigm of LSI systems, so-called "silicon photonics." In recent years remarkable progress has been made in the Si wire waveguide technologies for optical interconnection on a Si chip. In this paper, several Er embedded materials based on silicon are surveyed from the standpoint of application to the light emission and amplification devices for silicon photonics. We have concentrated to investigate an erbium silicate (Er2SiO5) as a light source medium for silicon photonics. To mention the particular features, this material has a layered structure with 0.86-nm period and a large amount of Er (25at%) as its constituent. The single crystalline nature gives several remarkable properties for the application to silicon photonics. We also discuss our recent studies of Er2SiO5 and a possibility of the shorter waveguide amplifier.