Germanium is an important semiconductor material used in transistors and various other electronic devices. Its major end uses are fibre-optic systems and infrared optics, but it is also used for polymerisation catalysts, as well as in electronics and solar cell applications. This book presents current research in the study of germanium, including properties and generation by irradiation of germanium point defects in Ge-doped silica; Germanium encaged fullerene-synthesis; research of silicon and germanium structures with films of oxides and fluoride rare earth elements and new generation germanium detectors for double beta decay searches.