InP high electron mobility transistors for submillimetre wave and terahertz frequency applications: A review

This paper reviews the rapid advancements being made in the development of high electron mobility transistors (HEMTs) on InP substrates for future sub-millimetre wave (30-300 GHz) and terahertz (300 GHz to 3.5 THz) frequency applications. The InP HEMTs exhibits outstanding 2-DEG properties in InAlAs/InGaAs heterostructure. This paper highlights the rapid growths in the developments of enhancement mode (E-Mode) and depletion mode (D-Mode) InP HEMTs over the last 40 years, the use of InP HEMTs for cryogenic applications, reliability issues and kink effects in InP HEMTs in detail and it also highlights the impact of geometrical dimensions and their scaling on the performance of InP HEMTs. Their uniqueness in terms of low noise, low power dissipation, high gain and high frequency of operation has fuelled the incorporation of InP HEMTs in a wide variety of applications such as high speed wireless and optical communication systems, sub-millimetre wave (S-MMW) and THz receivers and transmitters, radio astronomy and radiometry, flight communications and sensing applications, material spectroscopy, active and passive imaging applications, biomedical instrumentation applications and high speed ICs such as low noise amplifiers (LNAs), multiplier chains, switches, multiplexers and flip-flops.