6 MeV Au+ ion irradiation mechanism on SiC/SiO2 interface stability: focus on nitridation’s enhancement in radiation resistance

In aerospace radiation environments, the demand for SiC MOSFET devices with enhanced switching performance, superior high-temperature endurance, and radiation tolerance is continuously increasing. However, various ions in these environment can degrade the gate performance of such devices. To enhance the gate stability under radiation, high-fluence and low-energy gold ion radiation was performed on SiC/SiO₂ MOS structures. Two types of samples were tested: those that underwent oxidation only without annealing, and those that were treated with a NO annealing process after oxidation. The interfacial performance of these two types of samples was compared after radiation exposure. The experimental results indicated that at high radiation fluence, the non-nitrided samples lost their capacitance–voltage (C-V) characteristics, while the nitrided samples maintained good performance. Deep Level Transient Spectroscopy (DLTS) and X-ray Photoelectron Spectroscopy (XPS) were used to analyze changes in interface traps, energy levels, bonding configurations, and band structures. Scanning Electron Microscope (SEM) was used to observe changes in grain size and distribution at interfaces. The findings revealed that nitridation fills carbon vacancies caused by radiation, forms N-C bonds at the SiC/SiO₂ interface, and prevents the formation of carbon vacancy. These effects ensure the stability of the 4H-SiC/SiO₂ interface under radiation.