High permittivity dielectrics and suitable substrates are studies intensively in the view of their use in VLSI design. However, hafnium oxide (HfO2) is a promising candidate for the next generation of gate dielectrics due to its relatively high dielectric constant 25 , wide bandgap, good thermal stability, and relatively high free energy of reaction with the substrate material. Recently, Ge-based electronic devices have regained considerable attention and Ge can provide solutions to major problems that Si technology is facing for advanced CMOS devices; this is mainly due to the higher mo-bility of both the holes and the electrons in Ge substrate. Hence this book is useful for the readers to knew some significant issue on Ge technology for high frequency devices.