ENHANCEMENTS AND DEGRADATIONS IN ULTRASHORT GATE GAAS AND INP HEMTS PROPERTIES AT CRYOGENIC TEMPERATURES - AN OVERVIEW

Enhanced performances of III-V field effects transistors are generally expected at cryogenic temperatures thanks to the better confinement a nd the velocity of carriers. An overview of our recent work on ultrash ort gate-length HEMTs on GaAs and InP substrates at low temperature is presented in this paper. The compared behavior of the devices and the relative enhancement or degradation of their low and high frequency p roperties are discussed. The study is based on a set of device experim ental characterizations on chip and device simulations. At cryogenic t emperatures, trapping effects, impact ionization and classical short c hannel effects are enhanced while device self-heating associated with large current densities appear to decrease.