This book is the first to give a comprehensive description of the physics and applications of resonant tunneling diodes. The opening chapters of the book set out the basic principles of coherent tunneling theory. The authors describe in detail the effects of impurity scattering, femtosecond dynamics, non-equilibrium distribution, and intrinsic bistabilities. They review the applications of RTDs, such as in high-frequency signal generation and multi-valued data storage, and close the book with a chapter on the new field of resonant tunneling through laterally confined zero-dimensional structures. Covering all the key theoretical and experimental aspects of this active area of research, the book will be of great value to graduate students of quantum transport physics and device engineering, as well as to researchers in both these fields.