Microwave performance of all MOCVD-grown AlScN/GaN MIS-HEMTs on semi-insulating GaN substrates

We report on the design, fabrication, and characterization of AlScN/GaN metal–insulator–semiconductor high electron mobility transistors on semi-insulating GaN substrates. The layer is grown by MOCVD using (MCp)2ScCl precursor as the Sc source. Hall measurement shows a sheet carrier density of 1.12 × 1013 cm−2, a mobility of 813 cm2/V s, and a sheet resistance of 685 Ω/□. Devices with a gate length of 1 μm and gate–drain spacing of 0.9 μm exhibit a maximum drain current density of 1 A/mm, an on/off current ratio of 2 × 105, and a three-terminal breakdown voltage of 63 V. The device has near-ideal subthreshold characteristics with a subthreshold swing of 63 mV/dec and a current dispersion as low as 7.8% at 10 V due to the excellent interfacial quality with a trap density (Dit) of 2.11×1011cm−2eV−1 and the semi-insulating GaN substrate with a low threading dislocation density. Small-signal RF measurements reveal an fT/fmax of 25.8/51.1 GHz, while large-signal load-pull characterization at 10 GHz demonstrates an output power density of 4.04 W/mm with a power-added efficiency of 22.7%. In addition, a minimum noise figure below 2.5 dB is measured over a wide drain current range from 100 to 700 mA/mm below 6 GHz.