Hot electron effects and degradation of GaAs and InP HEMTs for microwave and millimetre-wave applications

This paper reviews the current knowledge of reliability and degradation issues connected with the presence of hot electron and impact ionization conditions in GaAs and InP HEMTs for high frequency analogue applications. The physical phenomena taking place in HEMTs at large drain-source electric fields (electron heating, real-space transfer, impact ionization, light emission, gate-drain breakdown) are first described, then the paper moves on to list and discuss the main degradation modes and mechanisms these conditions may bear. Finally, some conclusive remarks are given as to the main requisites for achieving hot electron robustness in HEMTs.