4500 V IEGTs having switching characteristics superior to GTO

In this paper, the authors report, for the first time, an exact prediction of the turn-off characteristics of 4500 V IEGTs and compare the results with those for GTOs. The prediction was made by means of device simulation and trial fabrication of IEGTs. The turn-off power loss of the 4500 V IEGT with a 17 μm deep trench gate is predicted to be less than that of the 4500 V GTO-thyristor. It was found that the IEGTs with 4 μm deep and wide trench gate can attain a small on-state voltage drop, which is the same level as that of the IEGT with 17 μm deep and narrow trench gate. The on-state voltage drop of the fabricated IEGT with the 4 μm deep trench gate is 4.5 V at 50 A/cm². Although the device design of the fabricated IEGT was not optimized, the observed turn-off characteristics were in good agreement with the simulated results. It has been numerically confirmed that the 4500 V IEGT can realize a smaller turn-off loss than a 4500 V GTO-thyristor under a typical application circuit. It was, thus, confirmed that IEGTs can replace GTOs without degradation of switching frequency