Normally-off fully recess-gated GaN metal–insulator–semiconductor field-effect transistor using Al2O3/Si3N4 bilayer as gate dielectrics

Abstract

By a self-terminating gate recess etching technique, a normally-off fully recess-gated GaN metal–insulator–semiconductor field-effect transistor (MISFET) was fabricated using Al2O3/Si3N4 bilayer as gate dielectrics. Owing to the high breakdown electric field (∼10 MV/cm) of the gate dielectrics, the device exhibits a large gate swing of 18 V, a high threshold voltage of 1.7 V (at ID = 100 µA/mm), a large maximum drain current of 534 mA/mm, a gate leakage current lower than 20 nA/mm in the whole gate swing, and a high OFF-state breakdown voltage of 1282 V. Furthermore, owing to the high gate overdrive (VGS − VTH), the on-resistance of the device only increases by 5.4% under a constant stress of VGS/VDS = 18 V/1 V.