Leakage Current Behavior in HfO2/SiO2/Al2O3 Stacked Dielectric on 4H-SiC Substrate

In this study, we investigate the deposition of high-k dielectric materials, namely Al2O3 and HfO2, using atomic layer deposition for 4H-SiC metal-oxide-semiconductor applications. C-V measurements reveal that the HfO2/SiO2/Al2O3/4H-SiC structure exhibits lower interface state density (Dit) and a reduced number of fixed interface trap charges (Neff) than the HfO2/Al2O3/SiO2/4H-SiC structure. Furthermore, we observe significant degradation of the interface properties when annealing at 400 °C compared with 300 °C, as evidenced by atomic force microscopy images. Transmission electron microscopy analysis shows that the SiO2/SiC surface is inhomogeneous and contains carbon clusters, while the Al2O3/SiC interface displays a more uniform structure. The I-V curves demonstrate a reduced leakage current for the high-k dielectric stacked structure to (10−11 A/cm2), and the breakdown electric field of the HfO2/SiO2/Al2O3/4H-SiC structure reaches 9.6 MV/cm.