Impact of T-gate electrode on gate capacitance in In_0.7Ga_0.3As HEMTs

The intrinsic and parasitic gate capacitance of In_0.7Ga_0.3As-channel high electron mobility transistors (HEMTs) are estimated by the gate delay analysis. We prepared 80-nm InGaAs HEMTs with different geometry of T-gate electrodes to discuss how the T-gate electrode affects parasitic gate delay. The results indicate that the both of the top part and stem of the T-gate electrode has an influence on the cutoff frequency of 80-nm-gate HEMTs and in total the parasitic gate delay caused by the T-gate electrode is more than half of the total gate delay.