Abstract
We report on 30-nm-gate-length InAlN/AlN/GaN/SiC high-electron-mobility transistors (HEMTs) with a record current gain cutoff frequency (fT) of 400 GHz. Although the high drain-induced barrier lowering (DIBL) value is indicative of significant short-channel effects, more than seven orders of magnitude in the current on/off ratio was observed. The high fT is a result of minimized parasitic effects and at the expense of a low power gain cutoff frequency (fMAX). The gate length dependence and temperature dependence of fT were also measured.