Studies on High-Voltage GaN-on-Si MIS-HEMTs Using LPCVD Si3N4 as Gate Dielectric and Passivation Layer

This paper investigates the performance of AlGaN/gallium nitride (GaN) MIS high electron mobility transistors (MIS-HEMTs). The gate dielectric layer and the surface passivation layer are formed by the low-pressure chemical vapor deposition (LPCVD) Si
₃
N
₄
. The LPCVD-Si
₃
N
₄
MIS-HEMTs exhibit a high breakdown voltage (BV) of 1162 V at I
_DS
= 1 μA/mm, a low OFF-state leakage of 7.7 × 10
^-12
A/mm, and an excellent ON/OFF-current ratio of ~10
¹¹
. Compared with the static ON-resistance of 2.88 mΩ · cm
²
, the dynamic ON-resistance after high OFF-state drain bias stress at 600 V only increases to 4.89 mΩ · cm
²
. The power device figure of merit = BV
²
/R
_ON.sp
is calculated to be 469 MW · cm
^-2
. The LPCVD-Si
₃
N
₄
/GaN interface state density is in the range of (1.4-5.3) × 10
¹³
eV
^-1
cm
^-2
extracted by the conventional conductance method. Finally, the gate insulator degradation of GaN-based MIS-HEMTs is analyzed by time-dependent dielectric breakdown test. The lifetime is extrapolated to 0.01% of failures after ten years at 300 K by fitting the data with a power law to a gate voltage of 10.1 V.