Ab initio theoretical and photoemission studies on formation of 4H-SiC(0 0 0 1)/SiO2 interface

Formation mechanisms of initial 4H-SiC (0 0 0 1)/SiO2 interface were analyzed by density functional theory (DFT) and angle-dependent X-ray photoelectron spectroscopy (ADXPS). Through the theoretical model calculations, either C or O interstitial is likely to exist in the oxidation process of 4H-SiC. Besides, there is one suboxide theoretically more easily to form and more stable than any others. The results of the ADXPS experiment revealed only one suboxide with shift of +0.94 eV relative to the 4H-SiC bulk component rather than three ones, which verified the theoretical results. These calculation and experimental results demonstrated there is only one rather than three silicon suboxides that induced the high density of states in the 4H-SiC/SiO2 interface. Besides, we did some speculations about the formation mechanism of the initial 4H-SiC/SiO2 interface according to the theoretical and experimental results.