A study on GTO turn-off failure mechanism

An infrared microscopic technology and exact one dimensional model were employed to clarify the processes which lead GTO to the gate turn-off failure. As a result of investigations, it was found that anode current density Jain the current crowding region is influenced by anode voltage ea. It finally increases approximately in the form of Ja= K.ea(K:Constant), accompanying temerature rise ΔT in the N-base region, which is proportional to ∫e²adt. Influences of device design parameters and external circuit conditions on the GTO turn-off failure were well explained by taking the constant K and allowable maximum temperature rise ΔT(max) into account. The safe operation area concept for a high power GTO snubber circuit design was quantitatively established, using the above results as a design criterion.