Mode-transition optimized 4.5 kV IGTT (IGBT mode turn-off thyristor)

A 4.5 kV IGBT mode turn-off thyristor (IGTT) with optimized mode-transition for realizing a low power loss, that is, a low forward voltage drop (V/sub f/) and a low turn-off loss (E/sub off/) is described for the first time. The device concept of optimizing the vertical carrier distribution was demonstrated by the IGBT mode turn-off operation combined with the proton(H/sup +/)-irradiation technique. The E/sub off/ value of 18 mJ/cm/sup 2/ was attained with V/sub f/ of 2.1 V at an anode current density of 25 A/cm/sup 2/. This value of E/sub off/ is 30 to 35% smaller than that for conventional MOS-gated thyristors. As a result, the trade-off relation between V/sub f/ and E/sub off/ is greatly improved for 4.5 kV devices.