Power semiconductor devices are undergoing dynamic evolution in the recent years. Modern power electronics era started by the invention of thyristor (or silicon controlled rectifier) in Bell Telephone Laboratory in 1956, and it was then commercially introduced by General Electric Company in 1958. Since then, we have seen the advent of triac, gate turn-off thyristor (GTO), bipolar power transistor and power MOSFET. The power semiconductors that appeared in the 1980's are insulated gate bipolar transistor (IGBT), static induction transistor (SIT), static induction thyristor (SITH) and MOS-controlled thyristor (MCT). The characteristics of these modern power devices have been discussed and compared from the viewpoint of power electronics applications. For completeness of description, other devices, such as thyristor, triac, GTO, bipolar transistor and power MOSFET have also been briefly reviewed. Finally, the trend of power converters has been discussed.