Zero voltage switching behavior of punchthrough and nonpunchthrough insulated gate bipolar transistors (IGBT's)

The switching performance of silicon (Si) punchthrough (PT) and a nonpunchthrough (NPT) insulated gate bipolar transistors (IGBT's) is compared under zero voltage switching (ZVS), both experimentally and using two-dimensional (2-D) device simulator. Extensive experimental results are obtained for both the devices under ZVS turn-on and turn-off, under a wide range of operating conditions. The switching performance is then analyzed using a finite element based device simulator which shows good agreement with the measured data. The device simulator is used to study the turn-on and turn-off behavior of the two devices. It is shown that, although both the devices behave similarly during ZVS turn-on, with the characteristic forward recovery voltage spike due to "conductivity modulation lag," the turn-off wave forms during ZVS are different for the two devices. Punchthrough device shows a "tail bump" during turn-off as opposed to a "tail plateau" shown by nonpunch-though device. The device simulator is used to study this difference in turn-off behavior. The simulator is also used to analyze the characteristic ZVS turn-on voltage wave form in more detail. Temperature dependence of the static and ZVS characteristics is also studied, for both the devices, and it is pointed out that turnoff of an NPT-IGBT is much less dependent on temperature as opposed to that of a PT-IGBT.