TEMPERATURE-DEPENDENCE OF THE EMITTER SWITCHED THYRISTOR CHARACTERISTICS

The effect of increasing the temperature on the characteristics of the EST is discussed in this paper. High temperature measurements were ma de on 600 V forward blocking multi-cell EST devices which were fabrica ted using an IGBT process sequence. An important feature of the EST is that the voltage drop across the lateral MOSFET, which is in series w ith the thyristor region, increases and compensates for the decrease i n the thyristor voltage drop at higher temperatures, producing an emit ter ballasting effect. Thus, the integration of this MOSFET in series with the thyristor results in a positive temperature coefficient for t he forward voltage drop at current densities above 167 A cm(-2) and a negative temperature coefficient below this current density. This beha vior Favors uniform current distribution and improved turn-off capabil ity. Experimental results indicate a decrease in the latching current density of the main thyristor and the parasitic thyristor with an incr ease in the ambient temperature. Transient measurements show an increa se in the turn-off time and a decrease in the maximum controllable cur rent density. These experimental results are supported and quantified by two-dimensional physics based models.