Improved Interface Properties and Dielectric Breakdown in Recessed AlGaN/GaN MOS-HEMTs Using HfSiO $_{{x}}$ as Gate Dielectric

In this letter, we report optimized transport properties in gate recessed enhancement-mode GaN MOS-HEMTs by incorporating silicon into atomic layer deposited gate dielectric HfO
₂
. Compared with commonly used HfO
₂
gate dielectric, the interface trap density can be reduced by nearly an order of magnitude and the fixed oxide traps inside are reduced to almost half using the high-quality passivation of HfSiO
_x
. The MOS-HEMTs based on HfSiO
_x
exhibit a threshold voltage of 1.5 V, excellent subthreshold swing of 65 mV/dec, and a high on-off ratio of 3 × 10
¹⁰
. The incorporation of silicon in HfO
₂
can also increase the dielectric breakdown property with maximum gate electric field of 2.85 MV/cm for a 10-year time-dependent gate dielectric breakdown lifetime, which is 36% higher than pure HfO
₂
. The maximum breakdown voltage of HfSiO
_x
MOS-HEMT is 742 V, which is 30% higher than HfO
₂
MOS-HEMT.