AlGaN/GaN HEMT With 300-GHz fmax

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 fmax, 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 Omega . mm, R-on of 1.1 similar to 1.2 Omega . mm, and fmax of 300 GHz, with a breakdown voltage of similar to 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.