Recent Developments of High-Voltage Light-Triggered Thyristors

13-kV light-triggered asymmetrical thyristors (LTT)s are studied by numerical simulations and first symmetrically blocking tandem structures-consisting of an asymmetrical thyristor connected in series with a diode-have been fabricated and characterized. It turned out that low-doped field stop layers favor fast turn-on of the subsequent amplifying gate structures. This had to be combined with anode emitter shunting. Our simulations show the very drastic effects of anode shunting, especially on the dv/dt reaction of the anode-side p-n
^-
-n-p
⁺
transistor of the asymmetrical thyristor. Another focus is on the dynamical behavior of the space charge region at optical (and subsequent electrical) amplifying gate triggering, which is different for symmetrical and asymmetrical thyristors. Our simulations indicate that both, intensity and localization of the high-power regions during turn-on are even more favorable in asymmetrical thyristors compared with symmetrical thyristors