In situ SiN_x gate dielectric by MOCVD for low-leakage-current ultra-thin-barrier AlN/GaN MISHEMTs on Si

摘要

In situ SiN_x grown by metal-organic chemical vapor deposition (MOCVD) was employed as the gate dielectric for ultra-thin-barrier AlN/GaN metal-insulator-semiconductor high electron mobility transistors (MISHEMTs) on Si substrates. Despite the ultra-thin barrier of 1.5 run, low reverse leakage current of below 10~(-7) A cm~(-2) was obtained with a 7 nm in situ SiN_x gate dielectric. The good surface passivation effects of in situ SiN_x were also demonstrated by the enhanced source/drain (S/D) current density and the reduced drain current degradation. Furthermore, interface trapping effects in the in situ SiN_x/AlN/GaN heterostructures were investigated by double-mode capacitance-voltage (C-V) measurements and frequency dependent conductance analysis. A trap states density of 1.9-3.4 × 10~(12) cm~(-2) eV~(-1) with a time constant of 0.8-17 μs were deduced.