This work examines some of the charge carrier transport issues encountered in the field of modern semi-conductor devices and novel materials. Theoretical approaches to the understanding and modelling of the relevant physical phenomena, seen in devices that have very small spatial dimensions and that operate under high electric field strength, are described in papers written by leading experts and pioneers in this field. In addition, the book examines the transport physics encountered in novel materials such as wide-band gap semi-conductors (GaN, SiC, among others) as well as organic semi-conductors.