Characterizations of InAlN/AlN/GaN transistors for S-band applications

InAlN/AlN/GaN high electron mobility transistors (HEMT) show interesting performances at level of static characteristics as well as at level of the behavior at microwave frequencies. This article presents an analysis of the impact of the variation of the topology of 2×100 μm devices on static I-V measurements and small signal parameters. Variations of the gate-drain distance and of the extension of the field plate linked to the source have an impact on the drain source output capacitance Cds and the drain source breakdown voltage Vds_BK. Pulsed I-V measurements on a 2×250 μm device reveal a decrease of 22 % of drain current because of gate lag effects. Nevertheless load-pull measurements of an 8×250 μm InAlN/AlN/GaN HEMT show good performances at 3.5 GHz with a power added efficiency (PAE) of 69 % and an output power (Pout) of 6.9 W/mm.