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

In this letter, we demonstrate a novel PEALD-AlN/LPCVD-Si
₃
N
₄
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 a GaN cap layer as recess mask. By using LPCVD-Si
₃
N
₄
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 18 V and a high channel effective mobility of 137 cm
²
/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 10
⁸
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 mQ · cm
²
, leading to a high Baliga's figure of merit of 945 MW/cm
²
.