Passivation and depassivation of interface traps at the SiO_2/4H-SiC interface by potassium ions

摘要

We investigate the passivation of interface traps by method of oxidizing Si-face 4H-SiC in the presence of potassium as well as examining the thermal stability of this passivation process. It is observed that this type of dry oxidation leads to a strong passivation of interface traps at the SiO_2/4H-SiC interface with energy levels near the SiC conduction band edge. Furthermore, it is observed that if potassium ions residing at the SiO_2/SiC interface are moved towards the sample surface by exposing them to ultraviolet light (UV) under an applied depletion bias stress at high temperatures the interface traps become electrically active again and are evidently depassivated. These findings are in line with recently a published model of the effect of sodium on such interface states.