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

Abstract

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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MAX</sub> of 101 GHz and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> ) of 21 V (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DG</sub> = 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.