The High Electron Mobility Transistor

2020 marked the 40th anniversary of the High‐Electron Mobility Transistor (HEMT). The HEMT represented a triumph for the, at the time, relatively new concept of bandgap engineering and nascent molecular beam epitaxy technology. The HEMT showcased the outstanding electron transport characteristics of two‐dimensional electron gas (2DEG) systems in III–V compound semiconductors. In the last 40 years, HEMTs have been demonstrated in several material systems, most notably AlGaAs/GaAs and AlGaN/GaN. Their uniqueness in terms of noise, power, and high‐frequency operation has propelled HEMTs to gain insertion in a variety of systems where they provide critical performance value. 2DEG systems have also been a boon in solid‐state physics where new and often bizarre phenomena have been discovered. As we look forward, HEMTs are uniquely positioned to expand the reach of electronics in communications, signal processing, electrical power management, and imaging. Some of the most exciting prospects in the near future for HEMT‐like devices are those of GaN for high‐voltage power management and 6G front‐end electronics. This paper briefly reviews some highlights of HEMT development in the last 40 years in engineering and science with emphasis on devices based on III–V arsenides and phosphides. It also speculates about potential future applications.