The dynamics of the thyristor turn-on process

In this paper, the early turn-on phases of thyristors axe examined using an exact two-dimensional numerical model. Two different thyristor structures are examined one with and one without an emitter short. Using three-dimensional plots of the carrier densities and observing the time dependence of the junction voltages, four separate turn-on phases are found. These phases are identified as an initial charging phase, a p-base delay phase, an n-base delay phase, and the final phase where the device is latched in an on-state and the anode current begins to flow. During each of the four phases, details of the carrier motion are investigated in order to help understand the physics of the turn-on process. Finally, experimental data on the anode current buildup for one of the device types are presented and compared with the predicted results.