Heterostructure Transistor Technology - A New Frontier in Microwave Electronics

Two transistors are taking over the lead in the race for highest speed: the High-Electron Mobility Transistor (HEMT) and the Heterojunction Bipolar Transistor (HBT). Both devices exploit unique aspects of electron transport at the interface between compound semiconductors of different bandgaps. These heterostructure transistors will expand the usable frequency range of three-terminal devices to 100 GHz. They will have the way for a rapidly expanding market in mm-wave monolithic circuits. This overview paper examines the potential of the two transistors, reviews the progress in microwave and digital applications and highlights future technical challenges.