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

Abstract

In situ SiNx 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 nm, low reverse leakage current of below 10−7 A cm−2 was obtained with a 7 nm in situ SiNx gate dielectric. The good surface passivation effects of in situ SiNx 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 SiNx/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 × 1012 cm−2 eV−1 with a time constant of 0.8–17 µs were deduced.