High performance E-mode InAlN/GaN HEMTs: Interface states from subthreshold slopes

Due to the high two-dimensional electron gas (2DEG) concentration and high temperature stability, lattice matched InAlN/AlN/GaN high electron mobility transistors (HEMTs) have attracted tremendous amount of interest for high-power and high-frequency electronics [1–2]. Employing the gate recess technology, a popular way to develop enhancement-mode (E-mode) devices for digital and mixed signal applications, record high performance (output current density of 2 A/mm, extrinsic transconductance of 890 mS/mm, and f
t
/f
max
of 95/135 GHz for 150-nm gate length) have been very recently reported on E-mode InAlN HEMTs [3]. Temperature dependent characterization of the subthreshold slope (SS) can provide valuable information on the interface states and their distribution near the band edges. In this paper, we have performed the field-effect measurements on these gate-recessed E-mod InAlN HEMTs reported in Ref. 3, and extracted the interface states from the temperature dependent SS from 80 to 300 K.