Power semiconductor devices have attracted increasing attention as key hardware in a variety of power conversion systems. Although the performance of Si power devices has remarkably been improved, silicon carbide (SiC) (and gallium nitride (GaN)) is promising for advanced high-voltage, low-loss and fast power devices, which can substantially outperform Si-based power devices. Through recent progress in SiC growth and device technologies, production of 600 –3300 V SiC power MOSFETs (metal-oxide-semiconductor field effect transistors) and Schottky barrier diodes has started, and remarkable improvement of energy efficiency has been demonstrated in real systems such as power supplies, air conditioners, photovoltaic power inverters, electric vehicles, and railcars. In spite of the promising potential of SiC power devices, various kinds of defects are present, which affect the performance and reliability of SiC devices. More importantly, basic understanding of material science associated with SiC is still very poor, leading to the lack of guidelines for defect control and thereby further improvement of device performance/reliability. In the first part of this seminar, the feature and present status of SiC power devices are briefly reviewed. Next, progress of defect electronics in SiC, especially on carbon vacancy, carrier lifetime, and MOS interface defects, is presented.