In this paper, some basic aspects related to defects and SiC devices performances are discussed. Our recent work is reviewed and inserted in the international research scenario. In particular, some issues relative to rectifying metal/SiC contacts will be treated in more detail. In fact, establishing a correlation between material defects, processing induced defects and irradiation induced defects with the electrical behaviour of Schottky contacts is extremely important for the future optimization of almost all electronic devices, sensors and particle detectors.