SiC and GaN from the viewpoint of vertical power devices

Wide-bandgap (WBG) semiconductors have attracted great attention as materials for the next-generation power devices since they have superior material properties compared to silicon (Si). The most advanced WBG semiconductor for power devices is silicon carbide (SiC). In 1987, the growth technology called “step-controlled epitaxy”, which enables single-phase (polytype) growth, was developed. In 1993–1994, SiC Schottky-barrier diodes (SBDs) which exceeds the Si material limit was demonstrated. In 2001, SiC SBDs were commercialized. Key technologies for SiC SBDs were edge termination to obtain an ideal breakdown voltage and a junction barrier Schottky (JBS) structure to suppress reverse leakage current. For power MOSFETs, it took longer time due to low channel mobility at SiO 2 /SiC and oxide reliability issues. Channel mobility was much improved by post-oxidation nitridation in NO or N 2 O ambient. Now, channel mobility and reliability are well controlled (balanced). SiC power MOSFETs as well as power modules with SiC MOSFETs and SiC SBDs, are commercially available. Last 5 years, the implementation of SiC devices into electronic vehicles and railway trains were extensively investigated, demonstrating a significant improvement of power efficiency.