Springer Series in materials science Electronic RF-communication and sensing systems have dramatically changed our daily lives since the invention of the first electronic transistor in 1947. Advanced semiconductor devices are key components within electronic systems and ultimately determine their performance. In this never ending challenge, wide-bandgap nitride semiconductors and heterostructure devices are unique contenders for future leading-edge electronic systems due to their outstanding material properties with respect to speed, power, efficiency, linearity, and robustness. At the same time, their material properties are challenging compared with any other material system due to high growth temperatures and many other intrinsic properties