Hot Electrons and Reliability in HEMTs

The renovated interest in the study of hot carrier phenomena in III-V FET devices originates from two main motivations: (i) the quest for higher on- state and off-state device breakdown voltages, which limit the maximum operating voltage of the devices; (ii) the need for an improved understanding of reliability problems due to hot carrier effects, which may lead to parametric degradation or burn-out phenomena. For III-V devices, the relevance of these phenomena, which were already well known for Si MOSFETs, was recognized at the beginning of this decade [1],[2]; in the following years, specific electrical measurements and electroluminescence techniques have been implemented and applied to the experimental characterization of hot carrier phenomena in MESFETs and HEMTs [3],[4]; standard reliability "life" tests have been modified in order to include "hot-electron" tests [5]; complex physical models have been developed in order to take into account impact-ionization phenomena and related effects [6].