The growth of semiconductor nanostructures and the study of their properties have been very active areas of research nano-device application. These novel nanostructures offer interesting prospects for the development of new electronic and photonic devices. Silicon micro photonics, a technology that merges photonics and silicon microelectronic components, is rapidly evolving. The main challenge is to develop efficient light sources out of silicon or silicon based materials. This allows one to combine the information-processing and information transport capabilities of electrons and photons on a Si-chip. The extension of research interests to germanium based nanostructures is rather straightforward, due to its higher carrier mobilities, higher excitonic Bohr radius and capability in forming group-IV heterostructures on Si substrates. During the course of this book, we have undertaken a systematic study on the synthesis and characteristics of Si/Ge based nanostructures for optical and electronic device applications.