Gate-assisted turnoff thyristors

A study of the turnoff physics in gate-assisted turnoff thyristors (GATT´s) leads to a proposed mechanism involving the gate bias acting to prevent a forward voltage from appearing on the cathode rather than, as was previously thought, to sweep out excess carriers. It is shown that cathode shunting can be used in GATT´s to virtually eliminate an important failure mode and to decrease the gate voltage needed to produce the desired improvement in turnoff time. Implications for designing GATT´s are given, one being that a change in the lateral resistance of the p-base will have opposite effects depending on whether the cathode is shunted or not.