823 mA/mm drain current density and 945 MW/cm2 Baliga’s figure of merit enhancement-mode GaN MISFETs with a novel PEALD-AlN/LPCVD-Si3N4 dual gate dielectric

摘要： In this letter, we demonstrate a novel PEALD-AlN/LPCVD-Si3N4 dual gate dielectric employed in enhancement-mode GaN MISFETs, where the gate recess is fabricated based on our proposed self-terminating gate recess etching technique using GaN cap layer as recess mask. By using LPCVD-Si3N4 and PEALD-AlN dual gate dielectric layer, the devices exhibit a high quality gate dielectric and a good GaN channel interface, yielding a high gate swing up to 18V and a high channel effective mobility of 137 cm2/V?s at such high gate bias. Thus, the fabricated devices feature a high maximum drain current density of 823 mA/mm, a threshold voltage of 2.6 V, an on-resistance of 7.4 Ω?mm, and an ON/OFF current ratio of 108 with gate-drain distance of 2 μm. Meanwhile, a high OFF-state breakdown voltage of 1290 V is achieved with 10 μm gate-drain distance. The corresponding specific on-resistance is as low as 1.76 mΩ?cm2, leading to a high Baliga’s ?gure of merit of 945 MW/cm2.