Charge induced in 6H-SiC nMOS capacitors by 15 MeV oxygen ion microbeams was measured using Transient Ion Beam Induced Current (TIBIC) before and after gamma-ray irradiations. The peak amplitude of TIBIC signals decreases and the fall time increases with increasing number of incident ions. The decrease in the TIBIC peak eventually saturated. The TIBIC signal can be refreshed to its original shape by applying a positive bias of + 1V to gate oxide. Small decrease in both the peak amplitude of TIBIC signal and collected charge was observed due to gamma-ray irradiation.