Nanoscale materials are showing great promise in various optoelectronics applications, especially the fast-developing fields of optical communication and optical computers. With silicon as the leading material for microelectronics, the integration of optical functions into silicon technology is a very important challenge. This book concentrates on the optoelectronic properties of silicon nanocrystals, associated phenomena and related topics, from basic principles to the most recent discoveries. The areas of focus include silicon-based light-emitting devices, light modulators, optical wavevguides and interconnectors, optical amplifiers and memory elements. The book comprises theoretical and experimental analyses of various properties of silicon nanocrystals, research methods and preparation techniques, and some promising applications.