GaN HEMTs with quaternary In0.05Al0.75Ga0.2N Schottky barrier layer

A quaternary InAlGaN Schottky barrier layer is used in GaN high electron mobility transistors (HEMTs) in this study. For potential application to high speed electronic devices, GaN HEMTs with a quaternary InAlGaN Schottky barrier layer are fabricated and characterized. The fabricated device shows a maximum drain current density of 1.8 A mm−1, a maximum trans-conductance of 557 mS mm−1, on/off current ratio higher than 105, a subthreshold swing (S.S.) of 140 mV/decade, and a gate-diode leakage current of 1.2 mA mm−1. For the device with a 100-nm-long gate footprint, a current gain cut-off frequency (fT) of 102 GHz and a maximum oscillation frequency (fmax) of 130 GHz are extracted at the same bias condition (VDS = 8 V and VGS = −2.2 V) whose Lg · fT product is evaluated to be 10.2 GHz · µm.