Semiconductor integrated circuits are essential in the current information society, as it is used in various applications including PCs and mobile phones. CMOS (complementary metal oxide semiconductor) transistor is a key component for integrated circuits. Continuous scaling down in transistor size has made possible increased performance of PCs and mobile phones. This book provides an introduction to new concepts, new materials such as high-k dielectrics and germanium, and new device structures. This book deals with recent advancement of nanoscale Si devices, including 3D structure, tunnel transistors for low power devices, and coupled quantum dots for spin-based qubit.