The IGBT is characterized by its ability to simultaneously handle a high voltage and a large current. The product of the voltage and the current density that the IGBT can handle reached more than 5 W/cm2, which far exceeded the value, 2 W/cm2, of existing power devices such as bipolar transistors and power MOSFETs. This is a consequence of the large safe operating area of the IGBT. The IGBT is the most rugged and the strongest power device that ever developed, thus, providing users with easy use of the device and displaced bipolar transistors and even GTOs.