The concepts in this book will provide a comprehensive overview of the current state for a broad range of nitride semiconductor devices, as well as a detailed introduction to selected materials and processing issues of general relevance for these applications. This compilation is very timely given the level of interest and the current stage of research in nitride semiconductor materials and device applications. This volume consists of chapters written by a number of leading researchers in nitride materials and device technology addressing Ohmic and Schottky contacts, AIGalnN multiple quantum well laser diodes, nitride vertical cavity emitting lasers, and ultraviolet photodetectors. This unique volume provides a comprehensive review and introduction to application and devices based on GaN and related compounds for newcomers to the field and stimulus to further advances for experienced researchers.