Based on the experience with silicon (Si) devices, some characteristics of silicon carbide (SiC) devices are likely to be misunderstood. In this paper, studies on channel mobility, time dependent dielectric breakdown (TDDB), and negative bias temperature instability (NBTI) in 4H-SiC MOSFETs are reviewed. Through the discussions, it is indicated that SiC-based models, such as local band gap modulation, and models for the relationship between defect energy state and SiC band gap are effective to understand the above characteristics.