Difference in kinetics between thermal nitridation and radical nitridation processes of 4H-SiC surface considering simultaneous N-incorporation and N-desorption reactions

Thermal nitridation is the most common methods for SiC surface defect passivation by introducing nitrogen on the surface, however, the nitridation process using active species such as N-radicals is one of the possible alternatives. This study investigated the kinetics of nitridation on SiC surface by N-radicals and compared them with those of thermal nitridation. Both processes showed a saturation of surface N density after prolonged nitridation, which is explainable by considering the competition between N-incorporation and N-desorption. N-desorption is driven by surface oxidation in the case of thermal nitridation, whereas it is caused by a heating in a high vacuum environment in the case of N-radical nitridation. In addition, N-incorporation rate reduction due to the depletion of surface reactive sites as N surface density increases must be taken into account in the case of radical nitridation.