Current distributions at the lateral spreading of electron-hole plasma in a thyristor

By using the potential probe method, the turn-on action of the three junctions of a thyristor associated with the plasma spreading was investigated as a function of the anode current density J
a
. By increasing J
a
, the width of the transient region between the ON and the OFF region was increased in the p-base layer but decreased in the n-base layer. The build up of the excess carriers in the p-base layer was due to the lateral field in the transient region, while in the n-base layer it was mainly due to the lateral diffusion from the ON region.