The effect of different passivations on near interface trap density of 4H-SiC/SiO2 structures

Recent experiments show the improvement of the inversion channel mobility of 4H-SiC MOSFETs after the gate post-oxidation annealing process [1-5]. Thus, further investigation of the post-oxidation annealing process is required to improve the channel mobility of 4H-SiC MOSFETs. This paper studies the effect of hydrogen, nitrogen, phosphorous, and arsenic passivation on total near interface trap density (Nit) and mobility of 4H(0001)-SiC/SiO₂ structures. Density Functional Theory (DFT) is used for calculation of the density of states (DOS), and the interface defect density (Dit) of several forms of 4H(0001)-SiC/SiO₂ structures. According to the calculated results, nitrogen, phosphorous, and arsenic annealing affect the channel mobility by decreasing the density of total near interface traps through the creation of strong silicon-nitrogen, silicon-phosphorous, and silicon-arsenic bonds at the interface.