Study of process of avalanche switching of silicon thyristors without bias voltage

Operation of the high-power thyristor without bias voltage switching in the impact-ionization mode was studied by numerical simulation methods. In calculations, the rate of voltage build-up on the dV/dt structure varied from 0.5 to 10 kV/ns, the temperature of the T structure was from 25 to 200 degrees C. It is shown that the increase in temperature affects the process of switching thyristors both due to an increase in the rate of thermal generation of carriers, and due to a decrease in the intensity of impact ionization processes. During switching processes of impact ionization occur at the same time in two regions of n-base: in the part of a base filled with the majority carriers and in the space charge region (SCR) near the n-p junction. At T >180 degrees C, owing to increase in concentration of thermo-generated carriers in the base, ionization processes occur only in SCR. It leads to increase in duration of switching process and increase in residual voltage. However, despite it if dV/dt >9 kV/ns, the effect of fast switching of the thyristor exists up to 200 degrees C.