In situ growth of SiN<i>_x</i>as gate dielectric and surface passivation for AlN/GaN heterostructures by metalorganic chemical vapor deposition

Abstract

SiNx grown in situ by metalorganic chemical vapor deposition (MOCVD) has shown great potential as a high-quality gate dielectric and surface passivation for AIN/GaN heterostructure transistors. In this paper, we present a thorough study on how the growth conditions affect the film quality of SiNx, and correlate the observed material properties with the electrical characteristics of the heterostructures. Lowering the growth pressure and SiH4/NH3 ratio can improve the SiNx/AIN interface roughness, leading to a reduced interfacial trap state density. The gate leakage current can be suppressed by increasing the resistivity of SiNx, which can be tailored with growth temperature and SiH4/NH3 ratio.