Comparative analysis of hot-phonon effects in nitride and arsenide channels for HEMTs

The cutoff frequency of a transistor is determined mainly by gate length and electron drift velocity. In general, the velocity reaches high values in a two-dimensional electron gas channel (2DEG). Thus, a high electron mobility transistor (HEMT) with a 2DEG channel can operate at frequencies corresponding to short millimeter waves. Though the highest values of drift velocity are similar for electrons in nitride and arsenide 2DEG channels, the frequency performance of an arsenide HEMT is superior, as compared with nitride HEMTs. However, it is not straightforward to see why hot phonons do not limit drift velocity in arsenide 2DEG channels and, in this paper, a comparative analysis of hot-phonon effects in AlInAs/GaInAs/AlInAs/InP, AlGaN/GaN and AlGaN/AlN/GaN channels is carried out.