101-GHz InAlN/GaN HEMTs on Silicon With High Johnson’s Figure-of-Merit

In this brief, the InAlN/GaN high-electron mobility transistors (HEMTs) on silicon substrate with high Johnson´s figure-of-merit (J-FOM) are presented. A trilayer photoresist of polymethylmethacrylate (PMMA)/copolymer/PMMA associated with a T-shaped gate is used to reduce the parasitic resistance while maintaining high current gain cutoff frequency. The small dc-to-RF transconductance dispersion of only 1.1% suggests a good quality SiNx passivation layer, and the f_MAX of 101 GHz and f_T of 60 GHz can be simultaneously obtained with a 0.11-μm foot length and 1.5-μm source-drain distance. In addition, the three-terminal OFF-state breakdown measurements reveal a source-drain breakdown voltage (BV_DS) of 21 V (V_DG = 31 V). The results lead to a high J-FOM of 1.3 THz · V, which has not been reported for the InAlN/GaN HEMTs on silicon substrate.