Chapter 1. Introduction.- Chapter 2.High Power High Frequency Transistors: A Materials Perspective.- Chapter 3. Isotope Engineering of GaN for Boosting Transistor Speeds.- Chapter 4. Linearity Aspects of High Power Amplification in GaN Transistors.- Chapter 5. III-Nitride Tunneling Hot Electron Transfer Amplifier (THETA).- Chapter 6.Plasma-Wave Propagation in GaN and Its Applications.- Chapter 7.Numerical Simulation of Distributed Electromagnetic and Plasma-wave Effect Devices.- Chapter 8.Resonant Tunneling Transport in Polar III-Nitride Heterostructures.- Chapter 9.Fabrication and Characterization of GaN/AlN Resonant Tunneling Diodes.- Chapter 10.Non-Contact Metrology for mm-wave and THz Electronics.