Two-State Trap-Assisted Tunneling Current Characteristics in Al2O3/SiO2/SiC Structures With Ultrathin Dielectrics

The two-state current conduction phenomenon in Al2O3/SiO2/SiC stacked structure was investigated by varying the process of dielectric preparation. All the devices exhibited obvious two-state current conduction behavior under I-V measurements. The threshold voltage of trap-assisted tunneling current conduction in the devices with Al2O3 layer prepared by HNO3 oxidation occurred at a smaller voltage than that by anodization; additionally, the former could be reset after positive bias stress with very small reset current but the latter could not. Meanwhile, the sample in SiO2 formation without UV light illumination exhibited faster electrical reset speed than that with UV light illumination. Both of endurance and retention characteristics were examined. The results show that different dielectric layer preparations strongly affect the characteristics of two-state current conduction in device with Al2O3/SiO2/SiC stacked structure.