AlGaN/GaN HEMT With 300-GHz $f_{\max }$

We report on a gate-recessed AlGaN/GaN high-electron mobility transistor (HEMT) on a SiC substrate with a record power-gain cutoff frequency (f_max). To achieve this high f_max, we combined a low-damage gate-recess technology, scaled device geometry, and recessed source/drain ohmic contacts to simultaneously enable minimum short-channel effects (i.e., high output resistance R_ds) and very low parasitic resistances. A 60-nm-gate-length HEMT with recessed AlGaN barrier exhibited excellent R_ds of 95.7 ????mm, R_on of 1.1 ~ 1.2 ?? ?? mm, and f_max of 300 GHz, with a breakdown voltage of ~ 20 V. To the authors´ knowledge, the obtained f_max is the highest reported to date for any nitride transistor. The accuracy of the f_max value is verified by small signal modeling based on carefully extracted S-parameters.